JP4263228B2 - Image processing method and image processing apparatus - Google Patents

Description

  The present invention relates to an image processing method and an image processing apparatus for a thermoreversible recording medium, and in particular, a high-contrast image can be obtained at high speed by forming a high-density uniform image and uniformly erasing the image in a short time. The present invention relates to an image processing method that can be repeatedly formed and erased, and an image processing apparatus that can be suitably used in the image processing method.

To date, image formation and image erasure on a thermoreversible recording medium (hereinafter sometimes simply referred to as “recording medium” or “medium”) are performed by contacting a heating source with the medium to heat the medium. It is done in the formula. As the heat source, a thermal head is usually used for image formation, and a heat roller, a ceramic heater, or the like is used for image erasure.
In such a contact-type recording method, when the recording medium is flexible, such as film or paper, uniform image formation and erasure are performed by pressing the medium uniformly against a heating source with a platen or the like. In addition, there is an advantage that an image forming apparatus and an image erasing apparatus can be manufactured at low cost by diverting parts of a conventional thermal paper printer.
However, when the recording medium incorporates an RF-ID tag or the like as described in Patent Document 1 and Patent Document 2, the thickness of the medium is increased, the flexibility is lowered, and the heating source is made uniform. High pressure is required to press against the surface. In addition, when unevenness is generated on the surface of the medium, it is difficult to form and erase an image using a thermal head or the like. Furthermore, while reading and rewriting of stored information is performed from where the RF-ID tag is separated without contact, there has been a demand for rewriting an image from a distant position of the thermoreversible recording medium.

In view of this, a method using a laser is considered as a method of forming irregularities on the surface of the recording medium or forming and erasing an image on the recording medium from a distance.
As a typical example of a conventional technique for recording and erasing a certain pattern using a laser, an optical disc such as a CD-RW or a DVD-RW can be cited. These form a pattern as stored information due to a difference in light reflectivity due to a change between a crystalline state and an amorphous state in an inorganic material such as Te, Se, In, and Ag. This change between the crystalline state and the non-crystalline state is caused by a difference in cooling rate after the material is melted by laser irradiation.
On the other hand, the thermoreversible recording medium changes between coloring and decoloring depending on the difference in heating temperature, which is how many times the medium is heated. That is, in the above optical disk, it is necessary to first heat the material to the melting temperature of the material in the same manner, and a pattern is formed by controlling the subsequent cooling rate. In the thermoreversible recording medium, In the case of image formation and image erasure, image formation and erasure are determined depending on how many times the medium has reached due to the laser irradiation heating regardless of the subsequent cooling rate. Even if a pattern is formed and erased, the process and mechanism are completely different.
Also, the difference in optical reflectivity between the crystalline state and the amorphous state of the optical disc is sufficient to irradiate a laser and electronically detect the difference in reflectivity, but it is only a slight reading visually. It was insufficient.

For example, Patent Document 3 discloses a method using a laser for forming and erasing an image on a recording medium when unevenness is generated on the surface of the thermoreversible recording medium or from a remote place. This is to perform non-contact recording using a reversible thermosensitive recording medium for a transport container used in a distribution line, writing is performed using a laser, and erasing is performed using hot air, hot water, an infrared heater or the like. Is disclosed.
As a printing and recording method using a laser, for example, Patent Document 4, Patent Document 5, Patent Document 6, and Patent Document 7 are disclosed.
In the technique described in Patent Document 4, after a photothermal conversion sheet is arranged on a thermoreversible recording medium, the photothermal conversion sheet is irradiated with laser light, and the generated heat generates an image on the thermoreversible recording medium. An improved image recording and erasing method including performing either of forming or erasing of the image, and in the specification, by controlling the irradiation condition of the laser beam, both the formation and erasing of the image are performed. It is disclosed that it can be done. That is, the heating temperature is controlled to the first specific temperature and the second specific temperature of the thermoreversible recording medium by controlling at least one of the light irradiation time, the light intensity, the focal point, and the light intensity distribution. In addition, it is described that image formation and erasure can be performed entirely or partially by changing the cooling rate after heating.
In Patent Document 5, two laser beams are used, one is erased as an elliptical or oval laser, the other is recorded with a circular laser, the method is recorded as a composite of two lasers, and 2 A method is described in which two lasers are deformed and recorded as respective composites. According to these methods, by using two lasers, it becomes possible to realize image recording with a higher density than recording with one laser.
The technique described in Patent Document 6 uses the front and back of one mirror at the time of laser recording and erasing, and changes the light beam shape of the laser light depending on the optical path difference and the mirror shape. As a result, it is possible to change the size of the light spot and blur the focus with a simple optical system.
Further, in Patent Document 7, the laser absorption rate of the label-like reversible thermosensitive recording medium is 50% or more, the irradiation energy at the time of printing is 5.0 to 15.0 mJ / mm ² , and the laser absorption rate and the printing irradiation. The product of the energy is 3.0 to 14.0 mJ / mm ² , and the product of the laser absorption rate at the time of erasing and the printing irradiation energy is set to 1.1 to 3.0 times, whereby the afterimage after erasing It is disclosed that the image can be erased substantially completely.
On the other hand, as an erasing method using a laser, for example, in Patent Document 8, the energy of laser light, the irradiation time of laser light, and the pulse width scanning speed are set to 25% or more and 65% or less during laser recording. There has been proposed a method for recording a clear contrast image on a highly durable reversible thermosensitive recording medium by erasing the image.

However, although printing and erasing with a laser can be performed by the method described above, since laser control is not performed during printing, local thermal damage occurs at a location where lines overlap during recording. There is a problem that the color density decreases when recording a solid image.
In order to solve these problems, methods for controlling printing energy are disclosed in Patent Document 9 and Patent Document 10.
In the above-mentioned patent document 9, the laser irradiation energy is controlled for each drawing point, and when the recording dots are printed so that the recording dots overlap each other or when folded, the energy applied to the portion is reduced, and the linear printing is performed. It is described that, when performing, energy is decreased at predetermined intervals to reduce local heat damage and prevent deterioration of the reversible thermosensitive recording medium.
In Patent Document 10, the irradiation energy is multiplied by the following expression, | cos0.5R | ^k (0.3 <k <4), in accordance with the angle R of the turning point at the time of laser drawing. I am trying to reduce energy. As a result, it is possible to prevent excessive energy from being applied to the overlapping portions of the line drawings when recording with a laser, to reduce the deterioration of the medium, or to maintain the contrast without reducing the energy excessively.
Further, as a method for preventing a decrease in color density, Japanese Patent Application Laid-Open No. H11-228707 discloses a sub-scanning dot arrangement pitch in order to prevent the previously recorded image from being erased when overwriting with a laser. It has been proposed to eliminate the reduction in color density and the generation of erasure traces by making the beam color radius at least twice the sum of the decoloring radius and the beam color radius.

Thus, the above-described method is devised so that excessive thermal energy is not applied to the thermoreversible recording medium due to the overlap during laser recording. However, when high-density printing and uniform erasing are repeated using a high-power laser, not only overlap occurs in the laser drawing part but also a phenomenon that the thermoreversible recording medium gradually deteriorates in the linear image part. To do. This is because the energy distribution of the laser beam to be irradiated is a Gaussian distribution, so that the energy in the central portion becomes extremely high. The central portion of the recording line image is excessively heated, and deformation marks and bubbles are observed on the thermoreversible recording medium. Especially in the medium portion corresponding to the central portion of the laser beam heated to a high temperature, the coloring and decoloring characteristics The material responsible for the material itself undergoes thermal decomposition, making it impossible to demonstrate sufficient ability. Therefore, uniform image formation and uniform image erasing at a high density cannot be sufficiently performed, and repeated erasure printing is insufficient as an image recording method with little deterioration.
Furthermore, when the thermo-reversible recording medium combined with the above-described RF-ID tag is used by being attached to a container or a container, irregularities occur on the surface of the medium, and the laser focal position is constant due to the irregularities. However, there is a problem that even when excessive energy is applied to the thermoreversible medium or when energy for performing erasure is added, the temperature rises to the coloring temperature, or conversely, erasure is insufficient and unerased residue is generated.

Although not rewritten, a so-called laser marker is known as a method for directly recording a lot number or model number on metal or plastic. This laser marker melts and decomposes metal and plastic with the energy of the laser to scratch the surface of the metal and plastic to form an image. For this purpose, the laser is focused and the laser irradiation section There was a need to increase the energy in the center of.
However, in a thermoreversible recording medium in which the transparency or color tone reversibly changes due to heat, when an image is formed by condensing a laser in the same manner as a normal laser marker, the temperature of the central part of the laser irradiation part becomes too high. When image formation and erasure are repeated, the portion deteriorates and the number of repetitions decreases. Further, if the laser irradiation energy is lowered so as not to raise the temperature of the central portion, there is a problem that the size of the image is reduced and the image contrast is lowered and it takes time to form the image.

JP 2004-265247 A JP 2004-265249 A Japanese Patent Application Laid-Open No. 2000-136022 Japanese Patent No. 3350836 Japanese Patent No. 3446316 JP 2002-347272 A JP 2004-195751 A JP 2003-246144 A JP 2003-127446 A JP 2004-345273 A JP 2004-1264 A

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, according to the present invention, a high-contrast image can be repeatedly formed and erased at high speed by forming a uniform image with high density and uniformly erasing the image in a short time on a thermoreversible recording medium. In addition, an object of the present invention is to provide an image processing method in which deterioration of the thermoreversible recording medium due to repeated formation and erasure is suppressed, and an image processing apparatus that can be suitably used in the image processing method.

Means for solving the above problems are as follows. That is,
<1> An image forming process for forming an image on the thermoreversible recording medium by irradiating and heating a thermoreversible recording medium in which either transparency or color tone reversibly changes depending on temperature. And at least one of an image erasing step of erasing an image formed on the thermoreversible recording medium by irradiating the thermoreversible recording medium with laser light and heating it,
In the light intensity distribution in the cross section substantially perpendicular to the traveling direction of the laser light in the laser light irradiated in at least one of the image forming step and the image erasing step, the light irradiation intensity at the central portion is the peripheral portion. It is the image processing method characterized by being below or equal to the light irradiation intensity of.
<2> An image forming step of forming an image on the thermoreversible recording medium by irradiating and heating a thermoreversible recording medium in which either transparency or color tone reversibly changes depending on temperature. And at least one of an image erasing step of erasing an image formed on the thermoreversible recording medium by irradiating the thermoreversible recording medium with laser light and heating it,
The image erasing step is to erase the image in the second image erasing area adjacent to the first image erasing area after erasing the image in the first image erasing area by scanning the laser beam. Including
The distance between the laser beam irradiation position to the first image erasing area and the laser beam irradiation position to the second image erasing area is 1/12 to 1/4 of the laser beam irradiation spot diameter. An image processing method characterized by the above.
<3> The image processing method according to <2>, wherein the laser beam irradiation spot diameter in the image erasing step is 1.2 to 38 times the laser beam irradiation spot diameter in the image forming step.
<4> A thermoreversible recording medium comprising at least a resin and a low-molecular-weight organic substance and reversibly changing either the transparency or the color tone depending on the temperature. An image forming step of forming an image on the thermoreversible recording medium, and an image erasing step of erasing the image formed on the thermoreversible recording medium by irradiating the thermoreversible recording medium with laser light and heating it. Including at least one of
The image forming step scans the laser beam to form an image in the first image forming area, and then forms an image in a second image forming area adjacent to the first image forming area. Including
After the low molecular weight organic substance located in the first image forming area is melted and before the low molecular weight organic substance is crystallized, the low molecular weight organic substance overlaps a part of the first image forming area. An image processing method comprising irradiating the second image forming area with the laser light.
<5> The organic low molecular weight substance in the thermoreversible recording medium is dispersed in the form of particles in the resin, and the transparency of the thermoreversible recording medium is reversibly changed by heat between a transparent state and a cloudy state <4>.
<6> The low molecular weight organic substance before melting is a leuco dye and a reversible developer, and after melting, the low molecular weight organic substance before crystallization is the leuco dye and the reversible developer. A color mixture with a colorant,
The image processing method according to <4>, wherein the color tone of the thermoreversible recording medium is reversibly changed by heat between a transparent state and a colored state.
<7> Any of the above <4> to <6>, wherein the irradiation of the laser beam to the first image forming region and the irradiation of the laser beam to the second image forming region are performed at intervals of 60 seconds or less. The image processing method according to claim 1.
<8> In the light intensity distribution in the cross section substantially perpendicular to the traveling direction of the laser light in the laser light irradiated in at least one of the image forming process and the image erasing process, the light irradiation intensity at the center is the periphery The image processing method according to any one of <2> to <7>, wherein the intensity is equal to or less than the light irradiation intensity of the portion.
<9> In the light intensity distribution in a cross section substantially perpendicular to the traveling direction of the laser light in the laser light, the light irradiation intensity at the center is 1.03 times or less of the light irradiation intensity at the peripheral part <1 > And <8>.
<10> The image according to <9>, wherein in the light intensity distribution in a cross section substantially perpendicular to the traveling direction of the laser light in the laser light, the light irradiation intensity at the center is smaller than the light irradiation intensity at the peripheral part. It is a processing method.
<11> Used in the image processing method according to any one of <1>, <8>, <9>, and <10>,
Laser beam emitting means;
An image processing apparatus having at least light irradiation intensity adjusting means arranged on a laser light emitting surface of the laser light emitting means and changing the light irradiation intensity of the laser light.
<12> The image processing apparatus according to <11>, wherein the light irradiation intensity adjustment unit is at least one of a lens, a filter, a mask, and a mirror.

In the first aspect, the image processing method of the present invention is formed on the thermoreversible recording medium by an image forming step of forming an image by irradiating the thermoreversible recording medium with laser light and heating it. In a cross-section substantially perpendicular to the traveling direction of the laser beam in the laser beam irradiated in at least one of the image forming step and the image erasing step, including at least one of image erasing steps for erasing the image In the light intensity distribution, the light irradiation intensity at the center is equal to or less than the light irradiation intensity at the peripheral part.
In the image processing method, in at least one of the image forming step and the image erasing step, a laser beam whose light irradiation intensity at the central portion in the light intensity distribution is equal to or less than that of the peripheral portion, The thermoreversible recording medium is irradiated. Therefore, unlike the case of using conventional Gaussian laser light, deterioration of the thermoreversible recording medium due to repeated image formation and erasure is suppressed, and a high-contrast image can be obtained without reducing the image size. It is formed.

In the second aspect, the image processing method according to the present invention includes at least one of the image forming step and the image erasing step, and the image erasing step scans the laser beam to generate a first image erasing region. And erasing the image in the second image erasing area adjacent to the first image erasing area, and irradiating the first image erasing area with the laser light irradiation position; The distance from the laser beam irradiation position to the image erasing region is 1/12 to 1/4 of the laser beam irradiation spot diameter.
In the image processing method, in the image erasing step, the interval between the laser light irradiation position on the first image erasing area and the laser light irradiation position on the second image erasing area is the laser light irradiation. The image which is irradiated with the laser beam so as to be 1/12 to 1/4 of the spot diameter and is located in the adjacent first image erasing area and the second image erasing area in the thermoreversible recording medium Is erased. As a result, the image formed on the thermoreversible recording medium is erased uniformly and in a short time.

In the third aspect, the image processing method of the present invention is for a thermoreversible recording medium comprising at least a resin and a low molecular weight organic substance, wherein either the transparency or the color tone reversibly changes depending on the temperature. , An image forming step for forming an image, and an image erasing step for erasing an image formed on the thermoreversible recording medium. Forming an image in a second image forming area adjacent to the first image forming area after forming an image in the first image forming area, and the organic small molecule located in the first image forming area After the substance is melted and before the organic low molecular weight substance is crystallized, the second image forming area is irradiated with the laser beam so as to overlap a part of the first image forming area.
In the image processing method, in the image forming step, after the low molecular weight organic substance located in the first image forming region is melted and before the low molecular weight organic substance is crystallized, The second image forming area is irradiated with the laser beam so as to overlap a part of the one image forming area. As a result, the first image formation is performed at an overlapping portion (boundary portion) between the laser light irradiation region on the first image forming region and the laser light irradiation region on the second image forming region. An image with high contrast and good uniformity can be obtained without erasing the image formed in the region.

The image processing apparatus of the present invention is used in the image processing method of the present invention, and is a laser beam emitting means, light disposed on the laser beam emitting surface of the laser beam emitting means, and light that changes the light irradiation intensity of the laser beam. And at least irradiation intensity adjusting means.
In the image processing apparatus, the laser beam emitting means emits a laser beam. The light irradiation intensity adjusting means changes the light irradiation intensity of the laser light emitted from the laser light emitting means. As a result, in the light intensity distribution in the cross section in the direction substantially perpendicular to the traveling direction of the laser light in the laser light, the light irradiation intensity at the central portion is equal to or less than the light irradiation intensity at the peripheral portion. When an image is formed on the thermoreversible recording medium using the laser beam having the light irradiation intensity adjusted in this way, deterioration of the thermoreversible recording medium due to repeated image formation and erasure is effectively suppressed.

  According to the present invention, the above-described problems can be solved, and a high-contrast image can be obtained by forming a high-density uniform image and uniformly erasing the image in a short time on a thermoreversible recording medium. Can be repeatedly formed and erased at high speed, and an image processing method in which deterioration of the thermoreversible recording medium due to repeated formation and erasure is suppressed, and an image processing apparatus suitable for use in the image processing method are provided. it can.

(Image processing method)
The image processing method of the present invention includes at least one of an image forming process and an image erasing process, and further includes other processes appropriately selected as necessary.
The image processing method of the present invention includes both an aspect in which both image formation and deletion are performed, an aspect in which only image formation is performed, and an aspect in which only image deletion is performed.

<Image forming process and image erasing process>
In the image processing method of the present invention, the image forming step is performed by irradiating and heating a thermoreversible recording medium in which either transparency or color tone reversibly changes depending on temperature, This is a step of forming an image on a thermoreversible recording medium.
The image erasing step in the image processing method of the present invention is a step of erasing an image formed on the thermoreversible recording medium by irradiating the thermoreversible recording medium with laser light and heating it.
By irradiating and heating the thermoreversible recording medium with the laser beam, it is possible to form and erase an image in a non-contact state with the thermoreversible recording medium.
In the image processing method of the present invention, the image is normally updated (the image erasing step) for the first time when the thermoreversible recording medium is reused, and then the image is formed by the image forming step. The order of forming and erasing is not limited to this, and the image may be erased by the image erasing step after the image is formed by the image forming step.

In the image processing method of the present invention, as will be described later, the laser beam irradiated in at least one of the image forming step and the image erasing step is substantially perpendicular to the traveling direction of the laser beam. In the light intensity distribution in the cross section, it is only necessary that the light irradiation intensity at the central part is equal to or less than the light irradiation intensity at the peripheral part. In the image forming step, the light irradiation intensity at the central part is the light irradiation intensity at the peripheral part. In the image erasing step, the light irradiation intensity at the central portion may not be equal to or less than the light irradiation intensity at the peripheral portion, and a heat source other than laser light is used. Also good. Among the heat sources, when heating by irradiating laser light, it takes time to scan and irradiate the entire predetermined area with one laser light. It is preferable to erase by heating using a heat roller, hot stamp, dryer or the like. In addition, when the foamed polystyrene box is equipped with the thermoreversible recording medium as a transport container for use in a distribution line, the foamed polystyrene box itself melts when heated, so that the thermoreversible recording is performed by irradiating a laser beam. It is preferable to erase by locally heating only the medium.
Further, in the image erasing step, when the light irradiation intensity at the central portion is equal to or less than the light irradiation intensity at the peripheral portion, the light irradiation intensity at the central portion in the image forming step is For example, a heat source other than a laser beam such as a thermal head may be used as the heat source.

In the first aspect of the image processing method of the present invention, in the laser beam irradiated in at least one of the image forming step and the image erasing step, the laser beam is substantially orthogonal to the traveling direction of the laser beam. In the light intensity distribution in the cross section, the light irradiation intensity at the center is equal to or less than the light irradiation intensity at the peripheral part.
In the image processing method according to the second aspect of the present invention, in the second aspect, the image erasing step scans the laser beam to erase the image in the first image erasing area, and then erases the first image. Erasing an image in a second image erasing area adjacent to the area, and an interval between a laser light irradiation position on the first image erasing area and a laser light irradiation position on the second image erasing area Is 1/12 to 1/4 of the irradiation spot diameter of the laser beam.
Furthermore, in the image processing method of the present invention, in the third aspect, the thermoreversible recording medium includes at least a resin and an organic low molecular weight substance, and the image forming step scans the laser light. And forming an image in a second image forming area adjacent to the first image forming area after forming an image in the first image forming area, wherein the image forming area is located in the first image forming area. After the low molecular weight organic substance is melted and before the low molecular weight organic substance is crystallized, the laser light is applied to the second image forming area so as to overlap a part of the first image forming area. Irradiate.

-First embodiment-
In the first aspect of the image processing method of the present invention, the laser beam irradiated in at least one of the image forming step and the image erasing step is substantially orthogonal to the traveling direction of the laser beam. In the light intensity distribution in the cross section (hereinafter sometimes referred to as “cross section orthogonal to the traveling direction of the laser beam”), the thermoreversibility is performed so that the light irradiation intensity at the central portion is equal to or less than the light irradiation intensity at the peripheral portion. The recording medium is irradiated with the laser light.
Conventionally, when any pattern is formed using a laser, the light intensity distribution in the cross section perpendicular to the traveling direction of the laser light has a Gaussian distribution, and the light irradiation intensity is at the center of light irradiation compared to the peripheral part. Was extremely strong. When the thermoreversible recording medium is irradiated with this Gaussian laser beam, the temperature in the central portion is excessively high, and when image formation and erasing are repeated, the portion deteriorates, and the number of repetitions decreases. When the laser irradiation energy is lowered so as not to raise the temperature of the part to a temperature that deteriorates, there is a problem that the size of the image is reduced, and the image contrast is lowered and image formation takes time.
Therefore, in the image processing method of the present invention, the light intensity of the central portion of the light intensity cloth of the cross section orthogonal to the traveling direction of the laser light irradiated in at least one of the image forming step and the image erasing step is Maintaining image contrast without reducing the size of the image while suppressing deterioration of the thermoreversible recording medium due to repeated image formation and erasure by making it less than or equal to the light irradiation intensity of the peripheral part As a result, repeated durability is improved.

[Center and periphery in light intensity distribution]
The “central portion” in the light intensity distribution of the cross section in a direction substantially orthogonal to the traveling direction of the laser light in the laser light is a downwardly convex 2 in a differential curve obtained by differentiating the curve representing the light intensity distribution twice. It means a part corresponding to a region sandwiched between the peak tops of two maximum peaks, and “peripheral part” means a part corresponding to a region excluding the “center part”.
The “light intensity at the center” is the peak top when the light intensity distribution at the center is represented by a curve, and the peak top when the shape of the light intensity distribution curve is convex upward. Means the light irradiation intensity at the peak bottom when the shape of the light intensity distribution curve is downwardly convex. Further, when the light intensity distribution curve has both an upward convex shape and a downward convex shape, it means the light irradiation intensity at the peak apex located at a position closer to the center in the central portion.
Further, when the light intensity distribution in the central part is represented by a straight line, it means the light irradiation intensity at the highest part of the straight line. In this case, the light irradiation intensity is constant in the central part ( It is preferable that the light intensity distribution in the central portion is represented by a horizontal line.
On the other hand, the “light irradiation intensity at the peripheral part” means the light irradiation intensity at the highest part when the light intensity distribution in the peripheral part is expressed by either a curve or a straight line.

Hereinafter, an example of the light irradiation intensity of the “central part” and the “peripheral part” in the light intensity distribution in the cross section orthogonal to the traveling direction of the laser light is shown in FIGS. 1A to 1E. In FIG. 1A to FIG. 1E, a curve representing the light intensity distribution, a differential curve (X ′) obtained by differentiating the curve representing the light intensity distribution once, and a curve representing the light intensity distribution are 2 in order from the upper side. This represents a differential curve (X ″) obtained by round differentiation.
1A to 1D show the light intensity distribution of laser light used in the image processing method of the present invention, and the light irradiation intensity at the central portion is equal to or less than the light irradiation intensity at the peripheral portion. Yes.
On the other hand, FIG. 1E shows a light intensity distribution of a normal laser beam, and the light intensity distribution is a Gaussian distribution, and the light irradiation intensity at the central portion is compared with the light irradiation intensity at the peripheral portion. And extremely strong.

In the light intensity distribution in the cross section orthogonal to the traveling direction of the laser beam, the light irradiation intensity between the central part and the peripheral part is equal to or less than the light irradiation intensity of the peripheral part. The equivalent or less means 1.05 times or less, preferably 1.03 times or less, more preferably 1.0 times or less, and the light irradiation intensity of the central portion. Is particularly smaller than the light irradiation intensity of the peripheral portion, that is, less than 1.0 times.
When the light irradiation intensity at the central portion is 1.05 times or less than the light irradiation intensity at the peripheral portion, deterioration of the thermoreversible recording medium due to a temperature rise at the central portion can be suppressed.
On the other hand, the lower limit of the light irradiation intensity at the central portion is not particularly limited and can be appropriately selected according to the purpose, but is preferably 0.1 times or more with respect to the light irradiation intensity at the peripheral portion. More preferably 3 times or more.
When the light irradiation intensity at the central portion is less than 0.1 times the light irradiation intensity at the peripheral portion, the temperature of the thermoreversible recording medium at the laser light irradiation spot does not rise sufficiently, and the peripheral portion On the other hand, the image density at the central portion may be lowered or the image may not be erased sufficiently.

As a laser that emits the laser beam is not particularly limited and may be suitably selected from those known in the art, CO ₂ laser, YAG laser, fiber laser, and the like semiconductor lasers (LD).
As a method of measuring the light intensity distribution in the cross section orthogonal to the traveling direction of the laser light, for example, when the laser light is emitted from a semiconductor laser, a YAG laser or the like and has a wavelength in the near infrared region, a CCD or the like It can be performed using a laser beam profiler using In addition, for example, when the laser beam is emitted from a CO ₂ laser and has a wavelength in the far infrared region, the CCD cannot be used. Therefore, a combination of a beam splitter and a power meter, a highly sensitive pyroelectric camera It can be performed using a high power beam analyzer or the like.

As a method of changing the light intensity distribution of the cross section orthogonal to the traveling direction of the laser light from the Gaussian distribution so that the light irradiation intensity at the central portion is equal to or less than the light irradiation intensity at the peripheral portion, the method is particularly limited. The light irradiation intensity adjusting means can be preferably used, although it can be appropriately selected according to the purpose.
Suitable examples of the light irradiation intensity adjusting means include a lens, a filter, a mask, and a mirror. Specifically, a kaleidoscope, an integrator, a beam homogenizer, an aspherical beam shaper (a combination of an intensity conversion lens and a phase correction lens) and the like are preferable. Moreover, when using a filter, a mask, etc., light irradiation intensity | strength can be adjusted by physically cutting the center part of the said laser beam. In the case of using a mirror, the light irradiation intensity can be adjusted by using a deformable mirror whose shape is mechanically changed in conjunction with a computer, a mirror having partially different reflectivity or surface irregularities, and the like.
It is also possible to adjust the light irradiation intensity by shifting the distance between the thermoreversible recording medium and the lens from the focal length. Furthermore, when a semiconductor laser, a YAG laser or the like is fiber coupled, The irradiation intensity can be easily adjusted.
A method for adjusting the light irradiation intensity by the light irradiation intensity adjusting means will be described in detail in the description of the image processing apparatus of the present invention to be described later.

-Second aspect-
In the second aspect of the image processing method of the present invention, after the image erasing step scans the laser beam to erase the image in the first image erasing area, the first image erasing area and Erasing an image in an adjacent second image erasing area, and an interval between a laser light irradiation position on the first image erasing area and a laser light irradiation position on the second image erasing area, It is 1/12 to 1/4 of the irradiation spot diameter of the laser beam.
As the interval between the laser light irradiation positions becomes smaller, the image is heated to a uniform temperature and the image can be erased uniformly. However, it takes a long time to erase an image formed over a wide area. On the other hand, the larger the interval between the laser beam irradiation positions, the more the image formed in a wide range can be erased. Therefore, the image can be erased in a short time, but the interval between the laser beam irradiation positions is increased. If the temperature is too high, the heating becomes non-uniform and defective erasing may occur.
In this aspect, the interval of the laser beam irradiation position to the adjacent first image erasing region and the second image erasing region is 1/12 to 1/4 of the irradiation spot diameter of the laser beam. Therefore, the image can be erased uniformly and in a short time.

[Irradiation spot diameter]
In general, the light intensity distribution in the cross-section orthogonal to the traveling direction of the output beam of the laser light has a substantially Gaussian distribution (light intensity distribution of the Gaussian beam). The main feature is that they have the same shape regardless of the beam transmission position. The light intensity distribution is expressed by the following formula 1, and the diameter that is 1 / e ² of the center intensity is called an irradiation spot diameter (or spot size, beam diameter, etc.), and as shown in FIG. Although the spot diameter includes 86.5% of the total light amount, in the first aspect of the image processing method having the light intensity distribution as shown in FIG. 2B, the diameter is not 1 / e ² of the center intensity, The diameter including 86.5% of the total light amount is set as the irradiation spot diameter.
<Formula 1>
I = 2P / πw ² · exp (-2r ² / w ² ) Equation 1
In Equation 1, r represents the distance from the laser center, w represents the radius of the laser beam (1 / e ^{2 of the} center intensity), and P represents the laser power.

The interval between the laser beam irradiation position on the first image erasing area and the laser beam irradiation position on the second image erasing area is 1/12 to 1/4 of the irradiation spot diameter of the laser light. If there is no particular limitation, it can be appropriately selected according to the purpose, but the lower limit is preferably 1/10 or more, and more preferably 1/8 or more. Moreover, as an upper limit, 1/5 or less is preferable.
The method for controlling the interval of the laser beam irradiation position to the image erasing region is not particularly limited and can be appropriately selected according to the purpose. For example, the method for controlling the interval for moving one of the galvanometers described later, etc. Is mentioned.
Here, as the image density of the image erasing area after image erasing, for example, the image density measured using a Macbeth densitometer (RD914) reversibly changes depending on the temperature of the thermoreversible recording medium. In this case, it is preferably 1.60 or more. When the color tone of the thermoreversible recording medium reversibly changes depending on temperature, it is preferably 0.09 or less. In this case, it is recognized that the image has been completely erased. In the aspect in which the transparency of the thermoreversible recording medium reversibly changes, measurement is performed with black paper (OD 2.0) on the back.

Moreover, it is preferable that the irradiation spot diameter of the laser beam in the image erasing process is 1.2 to 38 times the irradiation spot diameter of the laser beam in the image forming process.
When the irradiation spot diameter of the laser beam in the image erasing process exceeds 38 times the irradiation spot diameter of the laser light in the image forming process, the laser output necessary for heating to a certain temperature increases. In some cases, the size of the apparatus increases. In addition, if the scanning speed is slowed down in order to heat the laser output to a certain temperature without increasing the laser output, it takes time to erase the image.

The larger the irradiation spot diameter of the laser beam in the image erasing step is, the more preferable it is that the image formed in a wide range can be erased uniformly and in a short time. 1.5 times or more is more preferable with respect to the irradiation spot diameter of the laser beam, 2 times or more is more preferable, and 3 times or more is particularly preferable.
On the other hand, the upper limit of the laser beam irradiation spot diameter in the image erasing step is preferably 35 times or less, more preferably 20 times or less, relative to the laser beam irradiation spot diameter in the image forming step.
Specifically, the laser beam irradiation spot diameter in the image erasing step is preferably 1.7 to 6.9 mm, and more preferably 2.0 to 6.0 mm. On the other hand, the irradiation spot diameter of the laser beam in the image forming step is preferably 0.18 to 1.5 mm.

  The method of changing the laser beam irradiation spot diameter in the image erasing step to 1.2 to 38 times the laser beam irradiation spot diameter in the image forming step is not particularly limited, and is appropriately determined according to the purpose. For example, a method of changing the irradiation spot diameter of the laser beam for image formation and image erasing by moving the fθ lens or the thermoreversible recording medium in the laser beam irradiation direction, a scanning unit, For example, there are a method in which two optical systems such as an fθ lens are provided and an optical path is switched using the same optical resonator, and a method in which two recording apparatuses for image formation and image erasure are used.

Also in the second aspect of the image processing method of the present invention, the laser beam irradiated in at least one of the image forming step and the image erasing step is substantially perpendicular to the traveling direction of the laser beam. In the light intensity distribution in the cross section, it is preferable that the light irradiation intensity at the central portion is equal to or less than the light irradiation intensity at the peripheral portion. In this case, deterioration of the thermoreversible recording medium due to repeated image formation and erasure can be suppressed, and repeated durability can be improved while maintaining image contrast.
Further, even if the scanning speed of the laser beam is increased, the thermoreversible recording medium is uniformly heated, so that the image can be erased in a shorter time.
The details of the relationship between the light irradiation intensity at the central part and the light irradiation intensity at the peripheral part in the light intensity distribution in a cross section substantially perpendicular to the traveling direction of the laser light are as described above. .

-Third embodiment-
In the third aspect of the image processing method of the present invention, the thermoreversible recording medium includes at least a resin and an organic low molecular weight substance, and the image forming step scans the laser beam, Forming an image in a second image forming area adjacent to the first image forming area after forming an image in the first image forming area, and forming the organic low layer located in the first image forming area After the molecular material is melted and before the low-molecular-weight organic material is crystallized, the second image forming region is irradiated with the laser beam so as to overlap a part of the first image forming region. .

In the image forming step, when the laser beam is scanned to form an image, when it is necessary to form a line width that is thicker than a line width that can be formed by one scan, the line formed by the first scan It is necessary to cause the laser beam to be scanned twice or more times in the adjacent part. At that time, after an image is formed by the first scanning, if the second scanning is performed on a portion adjacent to the image, the temperature is lower than the image forming temperature between the first scanning position and the second scanning position. An image erasing temperature region occurs, and a part of the image formed by the first scanning is erased, resulting in a problem that image uniformity and image density are lowered. This is a fundamental problem of a thermoreversible recording medium that forms and erases an image depending on a difference in temperature.
Therefore, as a result of intensive studies on the color development / decoloration mechanism of the thermoreversible recording medium, the present inventors irradiated laser light by the first scanning for image formation, and heated the thermoreversible recording medium to reversibly. After melting the organic low molecular weight substance in the heat-sensitive recording layer (recording layer), before the organic low molecular weight substance crystallizes, the second scanning is performed on a portion adjacent to the image formed by the first scanning. When the laser beam is irradiated by the above, the image formed by the first scan is not erased at the boundary portion of the laser beam irradiation region by the first scan and the second scan, and the density is high and uniform. The inventors have found that an image with good properties can be obtained, and have completed the third embodiment of the image processing method of the present invention.

<Image formation and erasing mechanism>
The image forming and erasing mechanism includes an aspect in which the transparency changes reversibly depending on the temperature and an aspect in which the color tone changes reversibly depending on the temperature.
In the aspect in which the transparency changes reversibly, the organic low molecule in the thermoreversible recording medium is dispersed in particles in the resin, and the transparency is reversible by heat between a transparent state and a cloudy state. To change.
The visual recognition of the change in transparency results from the following phenomenon. That is, (1) in the transparent state, the organic low-molecular substance particles dispersed in the resin matrix and the resin matrix are in close contact with each other without any gap, and there are voids inside the particles. Therefore, the light incident from one side is transmitted to the opposite side without being scattered and looks transparent. On the other hand, in the case of (2) white turbidity, the particles of the low molecular weight organic substance are formed of fine crystals of the low molecular weight organic substance, and the interface between the crystal or the particle and the resin base material. A gap (gap) is generated, and light incident from one side is refracted and scattered at the interface between the gap and the crystal, or the interface between the gap and the resin, and thus appears white.

First, FIG. 3A shows the temperature of a thermoreversible recording medium having a reversible thermosensitive recording layer (hereinafter sometimes referred to as “recording layer”) in which the organic low molecular weight substance is dispersed in the resin. An example of a transparency change curve is shown.
For example, the recording layer is in a cloudy opaque state (A) at room temperature of T ₀ or less. As you heat it, it begins to slowly clear from the temperature T _1, temperature T ₂ when heated to through T ₃ transparent (B), and the even again returned to the normal temperature of T ₀ or less in this state transparent (D ). This is because the resin shrinks, reduces interfacial, or voids within the particles of the resin and the organic low-molecular material particle as the resin from the vicinity of the temperature T ₁ is started to soften, softening proceeds, gradually At temperatures T _{2 to} T ₃ , the organic low molecular weight material is in a semi-molten state, and the remaining voids become transparent by filling the organic low molecular weight material, and the seed crystal remains cooled. Since the resin is still in a softened state at that time, the resin follows the change in particle deposition accompanying crystallization, the voids do not occur, and the transparent state is maintained. It is believed that there is.
Further heating to a temperature of T ₄ or higher results in a translucent state (C) intermediate between maximum transparency and maximum opacity. Next, when this temperature is lowered, the first white turbid opaque state (A) is restored without becoming transparent again. This is because after the organic low molecular weight substance is completely melted at a temperature T ₄ or higher, it becomes supercooled and crystallizes at a temperature slightly higher than T _{0. At} that time, the resin follows the volume change accompanying the crystallization. It is thought that this is because voids cannot be generated.
However, in the temperature-transparency change curve shown in FIG. 3A, when the type of the resin, the organic low-molecular substance, or the like is changed, the transparency of each state may change depending on the type.

Further, FIG. 3B shows a transparency changing mechanism of the thermoreversible recording medium in which the transparent state and the cloudy state are reversibly changed by heat.
In FIG. 3B, one long-chain low-molecular particle and the surrounding polymer are taken out, and the generation and disappearance change of voids accompanying heating and cooling are illustrated. In the cloudy state (A), voids are generated between the polymer and the low molecular particles (or inside the particles), and the light scattering state is obtained. When this is heated and exceeds the softening point (Ts) of the polymer, voids decrease and transparency increases. When further heated to near the melting point (Tm) of the low molecular particle, a part of the low molecular particle is melted, and due to the volume expansion of the melted low molecular particle, the void is filled with the low molecular particle. Disappears and becomes transparent (B). When cooled from here, the low-molecular particles crystallize immediately below the melting point, no voids are generated, and the transparent state (D) is maintained even at room temperature.
Next, when heated to the melting point of the low molecular particle or higher, the refractive index between the molten low molecular particle and the surrounding polymer is shifted, and a translucent state (C) is obtained. When cooled to room temperature from this point, the low molecular particles undergo a supercooling phenomenon and crystallize below the softening point of the polymer. At this time, the polymer is in a glass state, so the volume associated with the crystallization of the low molecular particles The surrounding polymer cannot follow the decrease, and voids are generated to return to the original cloudy state (A).
As described above, even if the organic low molecular weight substance is heated to an image erasing temperature before it is crystallized, the organic low molecular weight substance is in a molten state and thus is supercooled, and the resin is crystallized in the organic low molecular weight substance. It is considered that a cloudy state occurs because it cannot follow the volume change due to the conversion and generates voids.

Next, in an aspect in which the color tone reversibly changes depending on temperature, the organic low molecular weight substance before melting may be referred to as a leuco dye and a reversible developer (hereinafter referred to as “developer”). The organic low-molecular substance after melting and before crystallization is the leuco dye and the developer, and the color tone is reversible by heat between a transparent state and a colored state. To change.
FIG. 4A shows an example of a temperature-color density change curve of a thermoreversible recording medium having a reversible thermosensitive recording layer containing the leuco dye and the developer in the resin, and FIG. The color development / decoloration mechanism of the thermoreversible recording medium in which the state and the color development state are reversibly changed by heat will be described.
First, when gradually heated the recording layer in First decolored state (A), at the melting temperature T _1, and the leuco dye and the color developer are mixed melt, molten color developed state caused color development ( B). When rapidly cooled from the melt color state (B), the color state can be lowered to room temperature, and the color state is stabilized and becomes a fixed color state (C). Whether or not this color development state has been obtained depends on the rate of temperature decrease from the melted state. In slow cooling, the color disappears in the process of temperature decrease, and the same color disappearance state (A) as the initial state or the color development state by rapid cooling ( The density is relatively lower than in C). On the other hand, when gradually raising the temperature again from the colored state (C), the color is erased at a lower temperature T ₂ than the coloring temperature (E from D), when the temperature is lowered from this state, the initial same decolorized state (A Return to).
The colored state (C) obtained by quenching from the molten state is a state in which the leuco dye and the developer are mixed in a state in which molecules can contact each other and form a solid state. There are many cases. In this state, the molten mixture of the leuco dye and the developer (the color mixture) crystallizes and maintains color development, and it is considered that the color development is stabilized by the formation of this structure. On the other hand, the decolored state is a state in which both phases are separated. This state is a state in which molecules of at least one compound aggregate to form a domain or crystallize, and the leuco dye and the developer are separated and stabilized by aggregation or crystallization. It is considered to be a state. In many cases, the color developer is crystallized as a result of the phase separation of the two, thereby causing more complete decoloring.
Incidentally, it is shown in Figure 4A, decoloring by slow cooling from the molten state, and aggregate structure also T ₂ both decoloring change after heating from the colored state, the crystallization of the phase separation and the color developer is caused ing.
As described above, when the developer is melted and heated to an image erasing temperature before the formed color mixture formed with the leuco dye is crystallized, separation of the leuco dye and the developer is hindered. As a result, it is considered that the colored state is maintained.

There is no particular limitation on the interval (time interval) between the irradiation of the laser beam onto the first image forming region and the irradiation of the laser beam onto the second image forming region. However, it is preferably within 60 seconds, more preferably within 10 seconds, still more preferably within 1.0 seconds, and particularly preferably within 0.1 seconds.
When the interval (time interval) exceeds 60 seconds, the organic low molecular weight substance is crystallized, and an image formed in the first image forming region and an image formed in the second image forming region are formed. A portion having a low image density may occur at the boundary with the image, and a uniform image may not be obtained.

The method for confirming that the organic low molecular weight substance is melted and in a state before crystallization, and the method for measuring the time until crystallization after the organic low molecular weight substance is melted are particularly limited. However, after forming a straight line image, a straight line image is formed so as to overlap in a vertical direction with respect to the straight line image after a predetermined time, and these intersections are erased. It can be done by judging whether or not. When the intersection is erased, it is recognized that the organic low molecular weight substance is crystallized.
The fact that the intersection portion is erased means that, for example, the image density of a linear image including the intersection portion is continuously measured using a Macbeth densitometer (RD914), and the transparency of the thermoreversible recording medium is reversible. In the changing aspect, the image density is 1.2 or more, and in the aspect in which the color tone of the thermoreversible recording medium is reversibly changed, the image density is 0.5 or less. In the aspect in which the transparency of the thermoreversible recording medium reversibly changes, measurement is performed with black paper (OD 2.0) on the back.
It is also possible to confirm whether the thermoreversible recording medium is crystallized by X-ray analysis. When the organic low molecular weight substance is crystallized, a unique crystal structure is shown according to the kind of the organic low molecular weight substance, and a scattering peak corresponding to the crystal structure can be detected by X-ray analysis. The scattering peak position can be easily confirmed by performing X-ray analysis of the organic low molecular weight substance alone. In addition, since it is possible to measure while changing the temperature depending on the X-ray analysis apparatus, it is possible to confirm the crystallization process of the organic low-molecular substance after heating and melting the organic low-molecular substance. it can.

There is no restriction | limiting in particular as a scanning speed of the said laser beam, Although it can select suitably according to the objective, 300 mm / s or more is preferable, 500 mm / s or more is more preferable, 700 mm / s or more is still more preferable.
When the scanning speed is less than 300 mm / s, the organic low molecular weight substance is crystallized, and an image formed in the first image forming area and an image formed in the second image forming area. A portion having a low image density may be generated at the boundary between the image density and the image density.
Moreover, there is no restriction | limiting in particular as an upper limit of the scanning speed of the said laser beam, Although it can select suitably according to the objective, 20,000 mm / s or less is preferable, 15,000 mm / s or less is more preferable, 10 More preferably, it is 1,000 mm / s or less.
If the scanning speed exceeds 20,000 mm / s, it may be difficult to form a uniform image.

Also in the third aspect of the image processing method of the present invention, the laser beam irradiated in at least one of the image forming step and the image erasing step is substantially orthogonal to the traveling direction of the laser beam. In the light intensity distribution in the cross section in the direction, it is preferable that the light irradiation intensity at the central portion is equal to or less than the light irradiation intensity at the peripheral portion. In this case, deterioration of the thermoreversible recording medium due to repeated image formation and erasure can be suppressed, and repeated durability can be improved while maintaining image contrast.
The details of the relationship between the light irradiation intensity at the central part and the light irradiation intensity at the peripheral part in the light intensity distribution in a cross section substantially perpendicular to the traveling direction of the laser light are as described above. .

[Thermal reversible recording medium]
The thermoreversible recording medium used in the image processing method of the present invention comprises at least a support and a reversible thermosensitive recording layer, and further appropriately selected as necessary, a protective layer, an intermediate layer, an under layer. It has other layers such as a coat layer, a back layer, a light-to-heat conversion layer, an adhesive layer, an adhesive layer, a colored layer, an air layer, and a light reflection layer. Each of these layers may have a single layer structure or a laminated structure.

-Support-
The support is not particularly limited in shape, structure, size and the like, and can be appropriately selected according to the purpose. Examples of the shape include a flat plate shape, May have a single layer structure or a laminated structure, and the size can be appropriately selected according to the size of the thermoreversible recording medium.

Examples of the material for the support include inorganic materials and organic materials.
Examples of the inorganic material include glass, quartz, silicon, silicon oxide, aluminum oxide, SiO ₂ and metal.
Examples of the organic material include paper, cellulose derivatives such as cellulose triacetate, synthetic paper, films of polyethylene terephthalate, polycarbonate, polystyrene, polymethyl methacrylate, and the like.
The said inorganic material and the said organic material may be used individually by 1 type, and may use 2 or more types together. Among these, organic materials are preferable, films of polyethylene terephthalate, polycarbonate, polymethyl methacrylate, and the like are preferable, and polyethylene terephthalate is particularly preferable.

For the purpose of improving the adhesion of the coating layer, the support is subjected to surface modification by performing corona discharge treatment, oxidation reaction treatment (chromic acid, etc.), etching treatment, easy adhesion treatment, antistatic treatment, etc. Is preferred.
Moreover, it is preferable to make it white by adding a white pigment such as titanium oxide to the support.
There is no restriction | limiting in particular as thickness of the said support body, Although it can select suitably according to the objective, 10-2,000 micrometers is preferable and 50-1,000 micrometers is more preferable.

-Reversible thermosensitive recording layer-
The reversible thermosensitive recording layer (hereinafter, sometimes simply referred to as “recording layer”) includes at least a material whose transparency and color tone reversibly change depending on temperature, and further, if necessary. It comprises other ingredients.
The material whose transparency and color tone reversibly change depending on the temperature is a material capable of exhibiting a phenomenon in which a visible change is reversibly caused by a temperature change, and the heating temperature and the cooling after the heating. Depending on the difference in speed, it can be changed between a relatively colored state and a decolored state. In this case, the visible change is divided into a color state change and a shape change. The change in the color state is caused by, for example, changes in transmittance, reflectance, absorption wavelength, scattering degree, etc., and the thermoreversible recording medium actually changes in color state due to a combination of these changes. To do.

The material whose transparency and color tone reversibly change depending on the temperature is not particularly limited and can be appropriately selected from known materials. For example, two or more kinds of polymers are mixed, Changes in transparency and white turbidity depending on the compatibility state (see JP-A-61-258853), using liquid crystal polymer phase-change (see JP-A-62-266990), higher than room temperature The first color temperature is changed to the first color state, heated to the second specific temperature higher than the first specific temperature, and then cooled to the second color state. It is done.
Among these, those in which the color state changes between the first specific temperature and the second specific temperature are particularly preferable in terms of easy temperature control and high contrast.
For example, a first color state is obtained at a first specific temperature higher than room temperature, and the second color state is obtained by heating at a second specific temperature higher than the first specific temperature and then cooling. And those heated at a third specific temperature higher than the second specific temperature.

Examples of these include a transparent state at the first specific temperature and a cloudy state at the second specific temperature (see Japanese Patent Application Laid-Open No. 55-154198), color development at the second specific temperature, (See JP-A-4-224996, JP-A-4-247985, JP-A-4-267190, etc.), a cloudy state at the first specific temperature, and the second specific A material that becomes transparent at a temperature (see Japanese Patent Application Laid-Open No. 3-169590), a color that develops black, red, blue, or the like at a first specific temperature and a color that disappears at a second specific temperature (Japanese Patent Application Laid-Open No. 2-188293) No., JP-A-2-188294, etc.).
Among these, a thermoreversible recording medium comprising a resin base material and an organic low molecular weight substance such as a higher fatty acid dispersed in the resin base material has a relatively low second specific temperature and first specific temperature, This is advantageous in that erasing printing with low energy is possible. In addition, since the color development / decoloration mechanism is a physical change that depends on the solidification of the resin and the crystallization of the organic low molecular weight substance, it has a strong environmental resistance.
In addition, a thermoreversible recording medium that uses a leuco dye and a reversible developer, which will be described later, to develop color at a second specific temperature and to erase at the first specific temperature is reversible between a transparent state and a colored state. In the colored state, black, blue, and other colors are shown, so that a high-contrast image can be obtained.

In the thermoreversible recording medium used in the third aspect of the image processing method, the organic low-molecular substance (dispersed in a resin matrix, becomes transparent at a first specific temperature, and becomes cloudy at a second specific temperature. As long as it changes from a polycrystal to a single crystal by heat in the pre-recording layer, it can be appropriately selected according to the purpose and generally has a melting point of 30 to 200 ° C. A material having a melting point of 50 to 150 ° C. is preferable.
Such an organic low molecular weight substance is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include alkanol; alkanediol; halogen alkanol or halogen alkanediol; alkylamine; alkane; alkene; alkyne; Alkane; Halogen alkene; Halogen alkyne; Cycloalkane; Cycloalkene; Cycloalkyne; Saturated or unsaturated mono- or dicarboxylic acid and ester, amide or ammonium salt thereof; Saturated or unsaturated halogen fatty acid and ester, amide or ammonium salt thereof Aryl carboxylic acids and their esters, amides or ammonium salts; halogen allyl carboxylic acids and their esters, amides or ammonium salts; thioalcohols; thiocarboxylic acids and their Ester, amine or ammonium salts; carboxylic acid esters of thioalcohol; and the like. These may be used individually by 1 type and may use 2 or more types together.

As carbon number of these compounds, 10-60 are preferable, 10-38 are more preferable, and 10-30 are especially preferable. The alcohol group part in the ester may be saturated or not saturated, and may be halogen-substituted.
In addition, the organic low molecular weight substance includes at least one selected from oxygen, nitrogen, sulfur and halogen, for example, —OH, —COOH, —CONH—, —COOR, —NH—, —NH in the molecule. ₂ , -S-, -SS-, -O-, a halogen atom and the like are preferable.
More specifically, these compounds include, for example, higher fatty acids such as lauric acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, behenic acid, nonadecanoic acid, alginic acid, and oleic acid; stearic acid Examples include esters of higher fatty acids such as methyl, tetradecyl stearate, octadecyl stearate, octadecyl laurate, tetradecyl palmitate, dodecyl behenate, and the like. Among these, as the organic low molecular weight substance used in the third aspect of the image processing method, higher fatty acids are preferable, and higher fatty acids having 16 or more carbon atoms such as palmitic acid, stearic acid, behenic acid, and lignoceric acid are more preferable. A higher fatty acid having 16 to 24 carbon atoms is more preferable.

  In order to widen the temperature range in which the thermoreversible recording medium can be made transparent, the above-mentioned various organic low molecular substances may be used in appropriate combination, or the organic low molecular substances may have different melting points. These materials may be used in combination. These are disclosed in, for example, Japanese Patent Application Laid-Open No. 63-39378, Japanese Patent Application Laid-Open No. 63-130380, Japanese Patent Application No. 63-14754, Japanese Patent No. 2615200, etc. Is not to be done.

The resin base material forms a layer in which the organic low molecular weight substance is uniformly dispersed and held, and affects the transparency at the time of maximum transparency. For this reason, the resin base material is preferably a resin having high transparency, mechanical stability, and good film forming properties.
There is no restriction | limiting in particular as such resin, According to the objective, it can select suitably, For example, polyvinyl chloride; Vinyl chloride-vinyl acetate copolymer, Vinyl chloride-vinyl acetate-vinyl alcohol copolymer, Vinyl chloride copolymers such as vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-acrylate copolymer; polyvinylidene chloride; vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, etc. Examples thereof include vinylidene chloride copolymers; polyesters; polyamides; polyacrylates or polymethacrylates or acrylate-methacrylate copolymers; silicone resins. These may be used alone or in combination of two or more.

The ratio of the organic low molecular weight substance and the resin (resin base material) in the recording layer is preferably about 2: 1 to 1:16, more preferably 1: 2 to 1: 8 in terms of mass ratio.
When the ratio of the resin is smaller than 2: 1, it may be difficult to form a film in which the organic low molecular weight substance is held in the resin base material. When the ratio is larger than 1:16, Since the amount of the organic low-molecular substance is small, it may be difficult to make the recording layer opaque.

In addition to the organic low molecular weight substance and the resin, other components such as a high boiling point solvent and a surfactant can be added to the recording layer in order to facilitate the formation of a transparent image.
The high boiling point solvent is not particularly limited and may be appropriately selected depending on the intended purpose.For example, tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate, tricresyl phosphate, butyl oleate, Dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-n-octyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate, dioctyl decyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, Dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate, di-2-ethylhexyl sebacate, diethylene glycol dibenzoate, triethylene glycol di-2 -Ethyl buty Over DOO, methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, and the like acetyl tributyl citrate.

  The surfactant and other components are not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include polyhydric alcohol higher fatty acid esters; polyhydric alcohol higher alkyl ethers; polyhydric alcohol higher fatty acid esters, Higher alcohols, higher alkylphenols, higher fatty acid higher alkylamines, higher fatty acid amides, fats or lower olefin oxide adducts of polypropylene glycol; acetylene glycol; Na, Ca, Ba or Mg salts of higher alkylbenzene sulfonic acids; higher fatty acids, aromatic carboxylic acids Ca, Ba or Mg salts of acids, higher fatty acid sulfonic acids, aromatic sulfonic acids, sulfuric monoesters or phosphoric mono- or di-esters; low sulfated oils; poly long-chain alkyl acrylates; acrylic-based oligomers; Chain alkyl Methacrylate; long chain alkyl methacrylate - amine containing monomer copolymer; a styrene - maleic anhydride copolymer; olefin - like maleic anhydride copolymer.

The method for producing the recording layer is not particularly limited and may be appropriately selected depending on the purpose. For example, a solution in which two components of the resin base material and the organic low molecular weight substance are dissolved, or the resin base For example, a dispersion liquid in which the organic low molecular weight substance is dispersed in the form of fine particles in a material solution (the solvent is insoluble in at least one selected from the organic low molecular weight substances) is applied onto the support, for example. And drying.
The solvent for producing the recording layer is not particularly limited and can be appropriately selected according to the kind of the resin base material and the organic low molecular weight substance. For example, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, four Examples include carbon chloride, ethanol, toluene, and benzene. In addition, when using the said dispersion liquid, also when using the said solution, in the obtained recording layer, the said organic low molecular weight substance precipitates as a fine particle, and exists in a dispersed state.

The organic low molecular weight substance in the thermoreversible recording medium used in the third aspect of the image processing method is composed of the leuco dye and the reversible developer, which develops color at a second specific temperature, It may be decolored at temperature.
The leuco dye is itself a colorless or light dye precursor. The leuco dye is not particularly limited and may be appropriately selected from known ones. Preferable examples include leuco compounds such as phthalocyanine, indophthalyl, spiropyran, azaphthalide, chromenopyrazole, methine, rhodamine anilinolactam, rhodamine lactam, quinazoline, diazaxanthene, and bislactone. Among these, a fluoran-based or phthalide-based leuco dye is particularly preferable in terms of excellent color development / decoloring characteristics, color, storage stability, and the like. These may be used individually by 1 type, may use 2 or more types together, and can also respond | correspond to multi-color and full color by laminating | stacking the layer which color-emits a different color tone.

The reversible developer is not particularly limited as long as it can reversibly develop and decolorize by using heat as a factor, and can be appropriately selected according to the purpose. For example, (1) A structure having a color developing ability for developing the leuco dye (for example, phenolic hydroxyl group, carboxylic acid group, phosphoric acid group, etc.), and (2) a structure for controlling cohesion between molecules (for example, long-chain hydrocarbon) Preferred examples include compounds having one or more structures selected from the group wherein the groups are linked to each other in the molecule. The linking moiety may be connected to a divalent or higher valent linking group containing a heteroatom, and the long-chain hydrocarbon group also contains at least one of the same linking group and aromatic group. May be.
Phenol is particularly preferred as the structure having the ability to develop (1) the leuco dye.
(2) The structure for controlling the cohesive force between molecules is preferably a long-chain hydrocarbon group having 8 or more carbon atoms, more preferably 11 or more, and the upper limit of the carbon number is 40 or less. Is preferable, and 30 or less is more preferable.

  Among the reversible developers, a phenol compound represented by the following general formula (1) is preferable, and a phenol compound represented by the following general formula (2) is more preferable.

In the general formulas (1) and (2), R ¹ represents a single bond or an aliphatic hydrocarbon group having 1 to 24 carbon atoms. R ² represents an aliphatic hydrocarbon group having 2 or more carbon atoms which may have a substituent, and the carbon number is preferably 5 or more, and more preferably 10 or more. R ³ represents an aliphatic hydrocarbon group of 1 to 35 carbon atoms, and carbon number, preferably 6 to 35, 8 to 35 is more preferable. These aliphatic hydrocarbon groups may be used alone or in combination of two or more.
The sum of the carbon numbers of R ¹ , R ² , and R ³ is not particularly limited and can be appropriately selected according to the purpose. However, the lower limit is preferably 8 or more, more preferably 11 or more. Preferably, the upper limit is preferably 40 or less, and more preferably 35 or less.
If the sum of the carbon numbers is less than 8, the color development stability and decoloring property may be lowered.
The aliphatic hydrocarbon group may be linear or branched, and may have an unsaturated bond, but is preferably linear. Examples of the substituent bonded to the hydrocarbon group include a hydroxyl group, a halogen atom, and an alkoxy group.
X and Y may be the same or different and each represents a divalent group containing an N atom or an O atom. Specific examples include an oxygen atom, an amide group, a urea group, and a diacylhydrazine. Group, oxalic acid diamide group, acylurea group and the like. Among these, an amide group and a urea group are preferable.
n shows the integer of 0-1.

  The reversible developer is preferably used in combination with a compound having at least one —NHCO— group and —OCONH— group in the molecule as a decoloring accelerator. In this case, in the process of forming the decolored state, an intermolecular interaction is induced between the decoloring accelerator and the reversible developer, and the color development / decoloring characteristics are improved.

  There is no restriction | limiting in particular as said decoloring promoter, Although it can select suitably according to the objective, For example, the compound etc. which are represented by following General formula (3)-(9) etc. are mentioned suitably.

In the general formulas (3) to (9), R ¹ , R ² , and R ^{4 each} represent a linear alkyl group having 7 to 22 carbon atoms, a branched alkyl group, or an unsaturated alkyl group. R ³ represents a methylene group having 1 to 10 carbon atoms. R ⁵ represents a trivalent functional group having 4 to 10 carbon atoms.

As a mixing ratio of the leuco dye and the reversible developer, an appropriate range varies depending on the combination of the compounds to be used and cannot be specified unconditionally, but the molar ratio is about the leuco dye 1. The reversible developer is preferably from 0.1 to 20, and more preferably from 0.2 to 10.
When the reversible developer is less than 0.1 or exceeds 20, the density of the colored state may be lowered.
Moreover, when adding the said decoloring promoter, 0.1-300 mass% is preferable with respect to the said reversible color developer, and its 3-100 mass% is more preferable.
In addition, the leuco dye and the reversible developer can be used in a microcapsule.

  When the organic low-molecular substance is composed of the leuco dye and the reversible developer, the reversible thermosensitive recording layer contains a binder resin, a crosslinking agent, etc. in addition to these components, and further if necessary. And other ingredients.

The binder resin is not particularly limited as long as the recording layer can be bound on the support, and one or two or more resins appropriately selected from known resins can be used in combination. it can.
As the binder resin, a resin that can be cured by heat, ultraviolet rays, electron beams, or the like is preferable in order to improve durability during repetition, and a thermosetting resin using an isocyanate compound or the like as a crosslinking agent is particularly preferable. .
Examples of the thermosetting resin include a resin having a group that reacts with a crosslinking agent such as a hydroxyl group or a carboxyl group, or a resin obtained by copolymerizing a monomer having a hydroxyl group, a carboxyl group, or the like with another monomer. Can be mentioned. Specific examples of such thermosetting resins include, for example, phenoxy resins, polyvinyl butyral resins, cellulose acetate propionate resins, cellulose acetate butyrate resins, acrylic polyol resins, polyester polyol resins, polyurethane polyol resins, and the like. It is done. Among these, acrylic polyol resin, polyester polyol resin, and polyurethane polyol resin are particularly preferable.

  The acrylic polyol resin uses a (meth) acrylic acid ester monomer, an unsaturated monomer having a carboxylic acid group, an unsaturated monomer having a hydroxyl group, and other ethylenically unsaturated monomers. It can be synthesized according to a known solution polymerization method, suspension polymerization method, emulsion polymerization method and the like.

  Examples of the unsaturated monomer having a hydroxyl group include hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl methacrylate (HPMA), and 2-hydroxybutyl. Examples include monoacrylate (2-HBA) and 1,4-hydroxybutyl monoacrylate (1-HBA). Among these, when a monomer having a primary hydroxyl group is used, 2-hydroxyethyl methacrylate is preferred because the crack resistance and durability of the coating film are good.

The mixing ratio (mass ratio) of the leuco dye and the binder resin in the recording layer is preferably 0.1 to 10 with respect to the leuco dye 1.
If the binder resin is less than 0.1, the thermal strength of the recording layer may be insufficient, and if it exceeds 10, the color density may decrease.

  There is no restriction | limiting in particular as said crosslinking agent, According to the objective, it can select suitably, For example, isocyanate, amino resin, a phenol resin, amines, an epoxy compound, etc. are mentioned. Among these, isocyanates are preferable, and polyisocyanate compounds having a plurality of isocyanate groups are particularly preferable.

  Examples of the isocyanates include hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), or adduct type, burette type, isocyanurate type, or blocking by trimethylolpropane. Isocyanates and the like.

The amount of the crosslinking agent added to the binder resin is preferably 0.01 to 2 in terms of the ratio of the functional group of the crosslinking agent to the number of active groups contained in the binder resin.
When the ratio of the functional groups is less than 0.01, the heat strength may be insufficient, and when it exceeds 2, the color development and decoloring characteristics may be adversely affected.

Furthermore, a catalyst used for this kind of reaction may be used as a crosslinking accelerator.
Examples of the crosslinking accelerator include tertiary amines such as 1,4-diazabicyclo [2,2,2] octane, and metal compounds such as organotin compounds.
The gel fraction of the thermosetting resin in the case of the thermal crosslinking is preferably 30% or more, more preferably 50% or more, and further preferably 70% or more.
When the gel fraction is less than 30%, the crosslinked state is not sufficient and the durability may be inferior.

  As a method for distinguishing whether the binder resin is in a crosslinked state or in a non-crosslinked state, for example, it can be distinguished by immersing the coating film in a highly soluble solvent. That is, the binder resin in the non-crosslinked state is dissolved in the solvent and does not remain in the solute.

  Examples of other components in the recording layer include various additives for improving and controlling coating characteristics, color development and decoloring characteristics. Examples of these additives include surfactants, plasticizers, conductive agents, fillers, antioxidants, light stabilizers, color development stabilizers, and decolorization accelerators.

The surfactant, the plasticizer, and the like are used from the viewpoint of facilitating image formation.
The surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant. It is done.
The plasticizer is not particularly limited and may be appropriately selected depending on the purpose. For example, phosphoric acid ester, fatty acid ester, phthalic acid ester, dibasic acid ester, glycol, polyester plasticizer, epoxy plasticizer Agents and the like.

A method for producing the recording layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, (1) the binder resin, the leuco dye, and the reversible developer are contained in a solvent. A method of coating the recording layer coating solution dissolved or dispersed in the support on the support and evaporating the solvent to form a sheet or the like, or thereafter crosslinking, (2) only the binder resin At the same time as coating the recording layer coating liquid in which the leuco dye and the reversible developer are dispersed in a solvent in which the solvent is dissolved, and by evaporating the solvent to form a sheet or the like, Or (3) without using a solvent, the binder resin, the leuco dye and the reversible developer are heated and melted and mixed together, and the molten mixture is formed into a sheet or the like. One that crosslinks after cooling , And the like.
In these, a sheet-like thermoreversible recording medium can be formed without using the support. In addition, the recording layer coating liquid may be prepared by dispersing each material in a solvent using a dispersing device, or may be individually dispersed in a solvent and mixed together. The material may be deposited by cooling.

There is no restriction | limiting in particular as a solvent used in (1) or (2) in the preparation methods of the said recording layer, Although it can select suitably according to the objective, The said binder resin, the said leuco dye, and the said reversible appearance Although it differs depending on the type of the colorant and cannot be generally specified, examples thereof include tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene, benzene and the like.
The reversible developer is dispersed in the form of particles in the recording layer.

Various pigments, antifoaming agents, pigments, dispersants, slip agents, preservatives, crosslinking agents, plasticizers, and the like are added to the recording layer coating solution for the purpose of developing high performance as a coating material. May be.
The recording layer coating method is not particularly limited and may be appropriately selected depending on the intended purpose. The recording medium is transported on the support in a roll form, continuously, or cut into a sheet form. For example, blade coating, wire bar coating, spray coating, air knife coating, bead coating, curtain coating, gravure coating, kiss coating, reverse roll coating, dip coating, die coating, etc. It can carry out using the well-known method of these.
The drying conditions for the recording layer coating liquid are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a temperature of room temperature to 140 ° C. for about 10 seconds to 10 minutes.
There is no restriction | limiting in particular as thickness of the said recording layer, Although it can select suitably according to the objective, For example, 1-20 micrometers is preferable and 3-15 micrometers is more preferable.
If the thickness of the recording layer is less than 1 μm, the color density may be low, and the contrast of the image may be lowered. In some cases, a portion that does not occur is generated, and a desired color density cannot be obtained.

-Protective layer-
The protective layer is preferably provided on the recording layer for the purpose of protecting the recording layer.
There is no restriction | limiting in particular as said protective layer, According to the objective, it can select suitably, For example, although you may form in multiple layers, it is preferable to provide in the outermost surface of the layer exposed.
The protective layer contains at least a binder resin, and further contains other components such as a filler, a lubricant, and a coloring pigment as necessary.

The binder resin for the protective layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, an ultraviolet (UV) curable resin, a thermosetting resin, an electron beam curable resin, and the like are preferable. Among these, ultraviolet (UV) curable resins and thermosetting resins are particularly preferable.
The UV curable resin can form a very hard film after curing, and can suppress damage due to physical contact with the surface and deformation of the medium due to laser heating, so that thermoreversible recording with excellent repeated durability A medium can be obtained.
In addition, although the thermosetting resin is slightly inferior to the UV curable resin, the surface can be similarly hardened, and a thermoreversible recording medium excellent in repeated durability can be obtained.

  The UV curable resin is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, urethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, vinyl And unsaturated polyester oligomers; monomers such as various monofunctional or polyfunctional acrylates, methacrylates, vinyl esters, ethylene derivatives, and allyl compounds; Among these, tetrafunctional or higher polyfunctional monomers or oligomers are particularly preferable. By mixing two or more of these monomers or oligomers, the hardness, shrinkage, flexibility, coating strength, etc. of the resin film can be appropriately adjusted.

In order to cure the monomer or oligomer using ultraviolet rays, it is necessary to use a photopolymerization initiator and a photopolymerization accelerator.
The photopolymerization initiator can be roughly classified into a radical reaction type and an ion reaction type, and the radical reaction type is further classified into a photocleavage type and a hydrogen abstraction type.

  The photopolymerization initiator is not particularly limited and may be appropriately selected depending on the intended purpose. For example, isobutyl benzoin ether, isopropyl benzoin ether, benzoin ethyl ether benzoin methyl ether, 1-phenyl-1,2-propane Dione-2- (o-ethoxysicarbonyl) oxime, 2,2-dimethoxy-2-phenylacetophenone benzyl, hydroxycyclohexyl phenyl ketone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one , Benzophenone, chlorothioxanthone, 2-chlorothioxanthone, isopropylthioxanthone, 2-methylthioxanthone, chlorine-substituted benzophenone, and the like. These may be used individually by 1 type and may use 2 or more types together.

  The photopolymerization accelerator is not particularly limited and can be appropriately selected according to the purpose. However, the photopolymerization accelerator has an effect of improving the curing rate with respect to a hydrogen abstraction type photopolymerization initiator such as a benzophenone series or a thioxanthone series. What has is preferable, for example, an aromatic tertiary amine, an aliphatic amine system, etc. are mentioned. Specific examples include p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, and the like. These may be used individually by 1 type and may use 2 or more types together.

  There is no restriction | limiting in particular as addition amount of the said photoinitiator and the said photoinitiator, Although it can select suitably according to the objective, 0.1-0.1 with respect to the total mass of the resin component of the said protective layer. 20 mass% is preferable and 1-10 mass% is more preferable.

Irradiation of ultraviolet rays for curing the ultraviolet curable resin can be performed using a known ultraviolet irradiation device, and examples of the ultraviolet irradiation device include a light source, a lamp, a power source, a cooling device, a conveyance device, and the like. And so on.
Examples of the light source include a mercury lamp, a metal halide lamp, a potassium lamp, a mercury xenon lamp, and a flash lamp.
The wavelength of the light emitted from the light source is not particularly limited and can be appropriately selected according to the ultraviolet absorption wavelength of the photopolymerization initiator and photopolymerization accelerator contained in the recording layer.
The irradiation conditions of the ultraviolet rays are not particularly limited and can be appropriately selected according to the purpose.For example, lamp output, conveyance speed, etc. can be appropriately determined according to irradiation energy necessary for crosslinking the resin. That's fine.

For the purpose of securing good transportability, silicone having a polymerizable group, a silicone grafted polymer, a wax, a release agent such as zinc stearate, a lubricant such as silicone oil, and the like can be added.
As these addition amount, 0.01-50 mass% is preferable with respect to the resin component total mass of the said protective layer, and 0.1-40 mass% is more preferable.
Even if the addition amount is small, the effect can be expressed, but if it is less than 0.01% by mass, it may be difficult to obtain the effect by addition, and if it exceeds 50% by mass, the adhesion to the lower layer may be obtained. May cause problems.
Further, the protective layer may contain an organic ultraviolet absorber, and the content thereof is preferably 0.5 to 10% by mass with respect to the total mass of the resin component of the protective layer.

Furthermore, in order to improve transportability, an inorganic filler, an organic filler, or the like may be added.
Examples of the inorganic filler include calcium carbonate, kaolin, silica, aluminum hydroxide, alumina, aluminum silicate, magnesium hydroxide, magnesium carbonate, magnesium oxide, titanium oxide, zinc oxide, barium sulfate, and talc. . These may be used individually by 1 type and may use 2 or more types together.
Moreover, it is preferable to use a conductive filler as a countermeasure against static electricity, and it is more preferable to use a needle-like filler as the conductive filler.
As the conductive filler, titanium oxide whose surface is coated with antimony-doped tin oxide is particularly preferable.
As a particle size of the said inorganic filler, 0.01-10.0 micrometers is preferable, for example, and 0.05-8.0 micrometers is more preferable.
The amount of the inorganic filler added is preferably 0.001 to 2 parts by mass, and more preferably 0.005 to 1 part by mass with respect to 1 part by mass of the binder resin in the protective layer.

  Examples of the organic filler include silicone resin, cellulose resin, epoxy resin, nylon resin, phenol resin, polyurethane resin, urea resin, melamine resin, polyester resin, polycarbonate resin, styrene resin, acrylic resin, polyethylene resin, formaldehyde Resin, polymethyl methacrylate resin and the like.

The thermosetting resin is preferably cross-linked. Therefore, as the thermosetting resin, for example, those having a group that reacts with a curing agent such as a hydroxyl group, an amino group, and a carboxyl group are preferable, and a polymer having a hydroxyl group is particularly preferable.
In order to improve the strength of the protective layer, the hydroxyl value of the thermosetting resin is preferably 10 or more, more preferably 30 or more, and 40 or more in that sufficient coating strength can be obtained. Further preferred. By imparting sufficient coating strength, deterioration of the thermoreversible recording medium can be suppressed even when repeated erasing and printing are performed.
As the curing agent, for example, the same curing agent as that used in the recording layer can be preferably used.

Moreover, the said protective layer may contain conventionally well-known surfactant, a leveling agent, an antistatic agent etc. as an additive.
Further, a polymer having an ultraviolet absorbing structure (hereinafter, sometimes referred to as “ultraviolet absorbing polymer”) may be used.
Here, the polymer having an ultraviolet absorbing structure means a polymer having an ultraviolet absorbing structure (for example, an ultraviolet absorbing group) in the molecule.
Examples of the ultraviolet absorbing structure include a salicylate structure, a cyanoacrylate structure, a benzotriazole structure, and a benzophenone structure. Among these, a bezotriazole structure and a benzophenone structure are particularly preferable in terms of good light resistance.
There is no restriction | limiting in particular as a polymer which has the said ultraviolet absorption structure, According to the objective, it can select suitably, For example, 2- (2'-hydroxy-5'-methacryloxyethylphenyl) -2H-benzotriazole and A copolymer composed of 2-hydroxyethyl methacrylate and styrene, a copolymer composed of 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2-hydroxypropyl methacrylate and methyl methacrylate, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2-hydroxyethyl methacrylate, methyl methacrylate and t-butyl methacrylate, 2 , 2,4,4-Tetrahydroxybenzophenone, 2-hydroxypropyl methacrylate and styrene And a copolymer of methyl methacrylate and propyl methacrylate. These may be used individually by 1 type and may use 2 or more types together.

  As the solvent, the coating liquid dispersing device, the protective layer coating method, the drying method and the like used in the protective layer coating solution, the known methods described in the preparation of the recording layer can be used. In addition, when using the said ultraviolet curable resin, after apply | coating and drying, the hardening process by ultraviolet irradiation is required, but an ultraviolet irradiation device, a light source, irradiation conditions, etc. are as above-mentioned.

There is no restriction | limiting in particular as thickness of the said protective layer, Although it can select suitably according to the objective, 0.1-20 micrometers is preferable, 0.5-10 micrometers is more preferable, 1.5-6 micrometers is still more preferable. .
When the thickness is less than 0.1 μm, the function as a protective layer of the thermoreversible recording medium cannot be fully exerted, and it is quickly deteriorated due to repeated history due to heat, and can be used repeatedly. If the thickness exceeds 20 μm, sufficient heat cannot be transmitted to the recording layer under the protective layer, and printing and erasing of images due to heat may not be sufficiently performed.

-Intermediate layer-
The intermediate layer improves adhesion between the recording layer and the protective layer, prevents alteration of the recording layer by application of the protective layer, prevents migration of additives in the protective layer to the recording layer, etc. For the purpose, it is preferably provided between the two. In this case, the storage stability of the color image can be improved.
The protective layer contains at least a binder resin, and further contains other components such as a filler, a lubricant, and a coloring pigment as necessary.

There is no restriction | limiting in particular as binder resin of the said intermediate | middle layer, According to the objective, it can select suitably, Resin components, such as binder resin in the said recording layer, a thermoplastic resin, and a thermosetting resin, can be used.
Examples of the binder resin include polyethylene, polypropylene, polystyrene, polyvinyl alcohol, polyvinyl butyral, polyurethane, saturated polyester, unsaturated polyester, epoxy resin, phenol resin, polycarbonate, polyamide, and the like.

The intermediate layer preferably contains an ultraviolet absorber.
There is no restriction | limiting in particular as said ultraviolet absorber, According to the objective, it can select suitably, For example, both an organic compound and an inorganic compound can be used.

Examples of the organic compound (organic ultraviolet absorber) include benzotriazole-based, benzophenone-based, salicylic acid ester-based, cyanoacrylate-based, and cinnamic acid-based ultraviolet absorbers. Among these, a benzotriazole type is preferable.
Among the benzotriazoles, those in which a hydroxyl group is protected with an adjacent bulky functional group are particularly preferable. For example, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole, 2 -(2'-hydroxy-3'-t-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5-chlorobenzotriazole and the like are preferable. Further, a polymer having a skeleton having such an ultraviolet absorbing ability may be pendant to a copolymerized polymer such as an acrylic resin or a styrene resin.
As content of the said organic type ultraviolet absorber, 0.5-10 mass% is preferable with respect to the resin component total mass of the said intermediate | middle layer, for example.

The inorganic compound (inorganic ultraviolet absorber) is preferably a metal compound having an average particle size of 100 nm or less, such as zinc oxide, indium oxide, alumina, silica, zirconia, tin oxide, cerium oxide, iron oxide, Antimony oxide, barium oxide, calcium oxide, barium oxide, bismuth oxide, nickel oxide, magnesium oxide, chromium oxide, manganese oxide, tantalum oxide, niobium oxide, thorium oxide, hafnium oxide, molybdenum oxide, iron ferrite, nickel ferrite, cobalt ferrite Metal oxides such as barium titanate and potassium titanate or composite oxides thereof; metal sulfides or sulfate compounds such as zinc sulfide and barium sulfate; titanium carbide, silicon carbide, molybdenum carbide, tungsten carbide, tan Le carbide or the like of metal carbides; aluminum nitride, silicon nitride, boron nitride, zirconium nitride, vanadium nitride, titanium nitride, niobium nitride, metal nitrides such as gallium nitride; and the like. Among these, metal oxide ultrafine particles are preferable, and silica, alumina, zinc oxide, titanium oxide, and cerium oxide are more preferable. Note that these surfaces may be treated with silicone, wax, organosilane, silica, or the like.
The content of the inorganic ultraviolet absorber is preferably 1 to 95% in terms of volume fraction.

The organic and inorganic ultraviolet absorbers may be contained in the recording layer.
Further, an ultraviolet absorbing polymer may be used, and it may be cured with a crosslinking agent. These are preferably the same as those used in the protective layer.
There is no restriction | limiting in particular as thickness of the said intermediate | middle layer, Although it can select suitably according to the objective, 0.1-20 micrometers is preferable and 0.5-5 micrometers is more preferable.
As the solvent used in the intermediate layer coating liquid, the coating liquid dispersing device, the intermediate layer coating method, and the intermediate layer drying / curing method, the known methods described in the preparation of the recording layer can be used. .

-Under layer-
In order to effectively utilize the applied heat to increase the sensitivity, or to improve the adhesion between the support and the recording layer and to prevent the recording layer material from penetrating into the support, the recording layer and the recording layer An under layer may be provided between the support and the support.
The under layer contains at least hollow particles, and contains a binder resin and, if necessary, other components.

Examples of the hollow particles include single hollow particles in which one hollow portion is present in the particles, and multi-hollow particles in which many hollow portions are present in the particles. These may be used individually by 1 type and may use 2 or more types together.
There is no restriction | limiting in particular as a material of the said hollow particle, Although it can select suitably according to the objective, For example, a thermoplastic resin etc. are mentioned suitably.
The void particles may be appropriately manufactured or may be commercially available products. Examples of the commercially available products include Microsphere R-300 (manufactured by Matsumoto Yushi Co., Ltd.), Ropaque HP 1055, Ropaque HP433J (all manufactured by Nippon Zeon Co., Ltd.), SX866 (manufactured by JSR Corporation), and the like.
There is no restriction | limiting in particular as the addition amount in the said under layer of the said hollow particle, Although it can select suitably according to the objective, For example, 10-80 mass% is preferable.

As the binder resin for the under layer, the same resin as the recording layer or the layer containing the polymer having the ultraviolet absorbing structure can be used.
The under layer can contain at least one of inorganic fillers such as calcium carbonate, magnesium carbonate, titanium oxide, silicon oxide, aluminum hydroxide, kaolin, and talc, and various organic fillers.
In addition, the under layer may further contain a lubricant, a surfactant, a dispersant, and the like.
There is no restriction | limiting in particular as thickness of the said under layer, Although it can select suitably according to the objective, 0.1-50 micrometers is preferable, 2-30 micrometers is more preferable, and 12-24 micrometers is still more preferable.

-Back layer-
A back layer may be provided on the side of the support opposite to the surface on which the recording layer is provided in order to prevent curling, antistatic and transportability of the thermoreversible recording medium.
The back layer contains at least a binder resin, and further contains other components such as a filler, a conductive filler, a lubricant, and a coloring pigment as necessary.

There is no restriction | limiting in particular as binder resin of the said back layer, According to the objective, it can select suitably, For example, a thermosetting resin, an ultraviolet-ray (UV) curable resin, an electron beam curable resin etc. are mentioned. . Among these, ultraviolet (UV) curable resins and thermosetting resins are particularly preferable.
About the said ultraviolet curable resin and the said thermosetting resin, the thing similar to what is used by the said recording layer, the said protective layer, and the said intermediate | middle layer can be used conveniently. The same applies to the filler, the conductive filler, and the lubricant.

-Photothermal conversion layer-
The photothermal conversion layer has a function of absorbing laser light and generating heat.
The photothermal conversion layer contains at least a photothermal conversion material having a role of absorbing laser light and generating heat.
The photothermal conversion material can be roughly classified into an inorganic material and an organic material.
Examples of the inorganic material include carbon black, metals such as Ge, Bi, In, Te, Se, Cr, and semimetals and alloys containing them, and these include vacuum deposition methods and particulate materials. A layer is formed by bonding with a resin or the like.
As the organic material, various dyes can be appropriately used according to the light wavelength to be absorbed. However, when a semiconductor laser is used as a light source, a near infrared having an absorption peak in the vicinity of 700 to 1,500 nm. Absorbing dyes are used. Specific examples include cyanine dyes, quinone dyes, quinoline derivatives of indonaphthol, phenylenediamine nickel complexes, and phthalocyanine dyes. In order to repeat printing and erasing repeatedly, it is preferable to select a photothermal conversion material having excellent heat resistance.
The near-infrared absorbing dye may be used alone or in combination of two or more, and may be mixed in the recording layer. In this case, the recording layer also serves as the photothermal conversion layer.
When the photothermal conversion layer is provided, the photothermal conversion material is usually used in combination with a resin. The resin used for the light-to-heat conversion layer is not particularly limited and can be appropriately selected from known ones as long as it can hold the inorganic material and the organic material. A curable resin or the like is preferable.

-Adhesive layer and adhesive layer-
The thermoreversible recording medium can be obtained in the form of a thermoreversible recording label by providing an adhesive layer or an adhesive layer on the opposite surface of the support to the recording layer forming surface.
The material of the adhesive layer and the adhesive layer is not particularly limited and can be appropriately selected from those generally used according to the purpose. For example, urea resin, melamine resin, phenol resin, epoxy Resin, vinyl acetate resin, vinyl acetate-acrylic copolymer, ethylene-vinyl acetate copolymer, acrylic resin, polyvinyl ether resin, vinyl chloride-vinyl acetate copolymer, polystyrene resin, polyester resin , Polyurethane resins, polyamide resins, chlorinated polyolefin resins, polyvinyl butyral resins, acrylic ester copolymers, methacrylic ester copolymers, natural rubber, cyanoacrylate resins, silicone resins, etc. It is done.

The material of the adhesive layer and the adhesive layer may be a hot melt type. Moreover, a release paper may be used and a non-release paper type may be used. By providing the adhesive layer or the pressure-sensitive adhesive layer in this way, the recording layer can be applied to the entire surface or a part of a thick substrate such as a magnetic stripe-added PVC card that is difficult to apply the recording layer. This improves the convenience of the thermoreversible recording medium, such as being able to display part of the information stored in the magnetism.
The thermoreversible recording label provided with such an adhesive layer or adhesive layer is also suitable for thick cards such as IC cards and optical cards.

-Colored layer-
The thermoreversible recording medium may be provided with a colored layer between the support and the recording layer for the purpose of improving visibility.
The colored layer can be formed by applying a solution or dispersion containing a colorant and a resin binder to a target surface and drying, or simply bonding a colored sheet.

The colored layer can be a color print layer.
Examples of the colorant in the color printing layer include various dyes and pigments contained in color inks used in conventional full color printing.
Examples of the resin binder include various thermoplastic, thermosetting, ultraviolet curable, and electron beam curable resins.
There is no restriction | limiting in particular as thickness of the said color printing layer, Since it changes suitably with respect to printing color density, it can select according to desired printing color density.

The thermoreversible recording medium may be used in combination with an irreversible recording layer. In this case, the color tone of each recording layer may be the same or different.
In addition, a part of the same surface as the recording layer of the thermoreversible recording medium, a part of the entire surface, or a part of the opposite surface, printing such as offset printing, gravure printing, or any picture by an inkjet printer, thermal transfer printer, sublimation printer, etc. In addition, an OP varnish layer mainly composed of a curable resin may be provided on a part or the entire surface of the colored layer.
Examples of the pattern include characters, patterns, patterns, photographs, information detected by infrared rays, and the like.
It is also possible to add a dye or pigment to any one of the simply configured layers for coloring.
Further, the thermoreversible recording medium can be provided with a hologram for security. In addition, in order to impart design properties, it is possible to provide a relief image, an intaglio shape, and a design such as a person image, a company emblem, or a symbol mark.

-Shape and application of thermoreversible recording medium-
The thermoreversible recording medium can be processed into a desired shape according to the application, for example, a card shape, a tag shape, a label shape, a sheet shape, a roll shape, or the like.
Moreover, what was processed into the card shape can be applied to a prepaid card, a point card, and further a credit card.
Furthermore, a tag-shaped size smaller than the card size can be used for a price tag or the like, and a tag-shaped size larger than the card size can be used for process management, a shipping instruction, a ticket, or the like.
Since the label can be affixed, it is processed into various sizes and can be affixed to carts, containers, boxes, containers, etc. that are repeatedly used and used for process management, article management, and the like. Further, when the sheet size is larger than the card size, the printing range is widened, so that it can be used for general documents, process management instructions, and the like.

-Example of combination with thermoreversible recording member RF-ID-
The thermoreversible recording member includes the reversible thermosensitive recording layer (recording layer) capable of reversible display and an information storage unit (integrated) on the same card or tag, and stores information stored in the information storage unit. By displaying the part on the recording layer, it is possible to check the information only by looking at the card or tag without a special device, which is excellent in convenience. In addition, when the contents of the information storage unit are rewritten, the thermoreversible recording medium can be used repeatedly many times by rewriting the display of the thermoreversible recording unit.
The information storage unit is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a magnetic recording layer, a magnetic stripe, an IC memory, an optical memory, and an RF-ID tag. It is done. When used for process management, article management, etc., an RF-ID tag can be particularly preferably used.
The RF-ID tag includes an IC chip and an antenna connected to the IC chip.

The thermoreversible recording member includes the recording layer capable of reversible display and an information storage unit, and a suitable example of the information storage unit is an RF-ID tag.
FIG. 5 shows an example of a schematic diagram of an RF-ID tag. The RF-ID tag 85 includes an IC chip 81 and an antenna 82 connected to the IC chip 81. The IC chip 81 is divided into four parts: a storage unit, a power supply adjustment unit, a transmission unit, and a reception unit. In communication, the RF-ID tag 85 and the reader / writer antenna communicate with each other by radio waves to exchange data. Specifically, there are two types, an electromagnetic induction method in which an RF-ID85 antenna receives a radio wave from a reader / writer and generates electromotive force by electromagnetic induction by a resonance action and a radio wave method activated by a radiated electromagnetic field. In both cases, the IC chip 81 in the RF-ID tag 85 is activated by an external electromagnetic field, converts the information in the chip into a signal, and then transmits a signal from the RF-ID tag 85. This information is received by the antenna on the reader / writer side and recognized by the data processing device, and data processing is performed on the software side.

The RF-ID tag is processed into a label shape or a card shape, and the RF-ID tag can be attached to the thermoreversible recording medium. The RF-ID tag can be attached to the recording layer surface or the back layer surface, but is preferably attached to the back layer surface.
In order to bond the RF-ID tag and the thermoreversible recording medium, a known adhesive or pressure-sensitive adhesive can be used.
The thermoreversible recording medium and the RF-ID tag may be integrated into a card shape or tag shape by laminating or the like.

An example of how to use the thermoreversible recording member that combines the thermoreversible recording medium and the RF-ID tag in process management will be described.
The process line in which the containers containing the delivered raw materials are transported is provided with means for writing a visible image in a non-contact manner on the display part while being transported, and means for non-contact erasing and further transmitting electromagnetic waves. The reader / writer for reading and rewriting the RF-ID information provided in the container without contact is provided. In addition, the process line is provided with a control means for automatically branching, weighing, managing, etc. on the physical distribution line using the individual information read and written without contact while the container is being conveyed. ing.
Information such as the article name and quantity is recorded on the thermoreversible recording medium and the RF-ID tag for the RF-ID thermoreversible recording medium attached to the container, and inspection is performed. In the next step, a processing instruction is given to the delivered raw material, information is recorded on the thermoreversible recording medium and the RF-ID tag, and a processing instruction is made and the processing proceeds. Next, order information is recorded in the thermoreversible recording medium and the RF-ID tag as an ordering instruction for the processed product, the shipping information is read from the container collected after the product is shipped, and the delivery container and the RF are again read. -Used as a thermoreversible recording medium with ID.
At this time, since it is non-contact recording to the thermoreversible recording medium using a laser, information can be erased and printed without peeling off the thermoreversible recording medium from a container or the like, and further to the RF-ID tag. Since information can be recorded in a non-contact manner, the process can be managed in real time, and information in the RF-ID tag can be simultaneously displayed on the thermoreversible recording medium.

(Image processing device)
The image processing apparatus of the present invention is used in the image processing method of the present invention, and includes at least a laser beam irradiation unit and a beam irradiation intensity adjustment unit, and further includes other members appropriately selected as necessary. Have.

-Laser light emitting means-
The laser beam emitting means is not particularly limited as long as the laser beam can be irradiated, and can be appropriately selected according to the purpose. For example, a CO ₂ laser, a YAG laser, a fiber laser, a semiconductor laser (LD), etc. And a commonly used laser.
The wavelength of the laser light emitted from the laser light emitting means is not particularly limited and can be appropriately selected according to the purpose, but is preferably from the visible region to the infrared region, and the image contrast is improved. The near infrared region to the far infrared region are more preferable.
In the visible region, for the image formation and erasure of the thermoreversible recording medium, the additive may be colored to absorb the laser light and generate heat, so that the contrast may be lowered.

The wavelength of the laser light emitted from the CO ₂ laser is 10.6 μm in the far infrared region, and the thermoreversible recording medium absorbs the laser light. Therefore, it becomes unnecessary to add an additive for absorbing the laser beam and generating heat. Further, even if a laser beam having a wavelength in the near infrared region is used, the additive may absorb visible light, but the CO ₂ laser that does not require the additive is There is an advantage that a decrease in image contrast can be prevented.

The wavelength of the laser light emitted from the YAG laser, the fiber laser, and the LD is in the visible to near infrared region (several hundred μm to 1.2 μm). Therefore, it is necessary to add a photothermal conversion material for absorbing laser light and converting it into heat. However, since the wavelength is short, there is an advantage that a high-definition image can be formed.
Further, since the YAG laser and the fiber laser have a high output, there is an advantage that the image formation and the erasing speed can be increased. Since the LD itself is small, there is an advantage that the apparatus can be downsized and the cost can be reduced.

-Light irradiation intensity adjustment means-
The light irradiation intensity adjusting unit has a function of changing the light irradiation intensity of the laser light.
The arrangement mode of the light irradiation intensity adjusting means is not particularly limited as long as it is arranged on the laser light emitting surface of the laser light irradiation means. You can choose.

The light irradiation intensity adjusting means calculates the light intensity distribution in a cross section substantially perpendicular to the traveling direction of the laser light from the Gaussian distribution, and the light irradiation intensity at the central portion is equal to the light irradiation intensity at the peripheral portion. It is preferable to have a function of changing so as to be equal or lower. Deterioration of the thermoreversible recording medium due to repeated image formation and erasure can be suppressed, and repeated durability can be improved while maintaining image contrast.
Note that the details of the relationship between the light irradiation intensity at the central portion and the light irradiation intensity at the peripheral portion in the light intensity distribution in a cross section substantially orthogonal to the traveling direction of the laser light are as described above. As described above in the description of the processing method.

There is no restriction | limiting in particular as said light irradiation intensity | strength adjustment means, Although it can select suitably according to the objective, For example, a lens, a filter, a mask, a mirror etc. are mentioned suitably. Specifically, for example, a kaleidoscope, an integrator, a beam homogenizer, an aspherical beam shaper (a combination of an intensity conversion lens and a phase correction lens) can be preferably used, and a physical filter or mask can be used. It is also possible to adjust the light irradiation intensity by cutting the central portion of the laser beam with the above. In the case of using a mirror, the light irradiation intensity can be adjusted by using a deformable mirror whose shape is mechanically changed in conjunction with a computer, a mirror having partially different reflectivity or surface irregularities, and the like.
Further, by adjusting the distance between the thermoreversible recording medium and the fθ lens, the light irradiation intensity at the central portion can be changed to be equal to or less than the light irradiation intensity at the peripheral portion. That is, when the distance between the thermoreversible recording medium and the fθ lens is shifted from the focal length, the light intensity distribution in a cross section substantially perpendicular to the traveling direction of the laser light is changed from the Gaussian distribution. , The distribution can be changed to a distribution in which the light irradiation intensity in the central portion is lowered.
Further, if a semiconductor laser, a YAG laser, or the like is coupled as a laser light source, the light irradiation intensity can be easily adjusted.

An example of a method for adjusting the light irradiation intensity using an aspherical beam shaper as the light irradiation intensity adjusting means will be described below.
For example, when a combination of an intensity conversion lens and a phase correction lens is used, as shown in FIG. 6A, two aspherical lenses are disposed on the optical path of the laser light emitted from the laser light emitting means. To do. Then, by the first aspherical lens L1, at the target position (distance l), the light irradiation intensity at the central portion in the light intensity distribution is equal to or less than the light irradiation intensity at the peripheral portion (in FIG. 6A). The strength is converted to a flat top shape. Thereafter, in order to propagate the intensity-converted beam (laser light) in parallel, the phase is corrected by the second aspheric lens L2. As a result, the Gaussian-distributed light intensity distribution can be changed.
As shown in FIG. 6B, only the intensity conversion lens L may be disposed on the optical path of the laser light emitted from the laser light emitting means. In this case, with respect to an incident beam (laser light) distributed in a Gaussian manner, a portion having a high intensity (inside) diffuses the beam as indicated by X1, and conversely, a portion having a low intensity (outside) is indicated by X2. By converging the beam, the light irradiation intensity at the central part in the light intensity distribution can be converted to be equal to or less than the light irradiation intensity at the peripheral part (in FIG. 6B, a flat top shape).
Furthermore, an example of a method for adjusting the light irradiation intensity using a combination of a fiber-coupled semiconductor laser and a lens as the light irradiation intensity adjusting means will be described below.
In a fiber-coupled semiconductor laser, laser light propagates through the fiber while being repeatedly reflected. Therefore, the light intensity distribution of the laser light emitted from the fiber end is different from the Gaussian distribution, and the Gaussian distribution and the flatness are different. The light intensity distribution corresponds to the middle of the top shape. A combination of a plurality of convex lenses and / or concave lenses as a condensing optical system is attached to the fiber end so that such a light intensity distribution becomes the flat top shape. Then, when the distance to the thermoreversible recording medium is a focal length, the flat top shape is obtained, but when the position is slightly deviated from the focal length, the light intensity distribution of the obtained laser light is At a position where the distance to the thermoreversible recording medium is greatly different from the focal length, the light intensity at the central portion is smaller than the light intensity at the peripheral portion as shown in FIG. 1D. Intensity distribution. The light irradiation intensity at the central portion at this time can be easily adjusted by changing the distance to the thermoreversible recording medium.

The image processing apparatus of the present invention has the same basic configuration as that of what is usually called a laser marker except that it has at least the laser beam emitting unit and the light intensity adjusting unit, and includes an oscillator unit, power control At least a unit and a program unit are provided.
Here, FIG. 7 shows an example of the image processing apparatus of the present invention, centering on the laser irradiation unit.

The image processing apparatus shown in FIG. 7 has a central portion of a laser beam as the light irradiation intensity adjusting means in the optical path of a laser marker having an output of 40 W CO ₂ laser (manufactured by Sunkus Co., Ltd., LP-440). A mask to be cut (not shown) is incorporated, and the light intensity distribution in the cross section orthogonal to the traveling direction of the laser light can be adjusted so that the light irradiation intensity at the center changes with respect to the light irradiation intensity at the peripheral part.
The specifications of the laser irradiation unit, that is, the image recording / erasing head part, are: possible laser output range: 0.1 to 40 W, irradiation distance movable range: no particular limitation, spot diameter range: 0.18 to 10 mm, scan Speed range: max 12,000 mm / s, irradiation distance range: 110 mm × 110 mm, focal length: 185 mm.

The oscillator unit includes a laser oscillator 10, a beam expander 12, a scanning unit 15, an fθ lens 16, and the like.
The laser oscillator 10 is necessary for obtaining laser light having high light intensity and high directivity. For example, mirrors are arranged on both sides of the laser medium, and the laser medium is pumped (energy supply). The stimulated emission is caused by increasing the number of atoms in the excited state and forming an inversion distribution. Then, only the light in the optical axis direction is selectively amplified, so that the directivity of the light is enhanced and the laser light is emitted from the output mirror.
The scanning unit 15 includes a galvanometer 14 and a mirror 14A attached to the galvanometer 14. The laser light output from the laser oscillator 10 is scanned at high speed on the thermoreversible recording medium S by scanning at high speed with two mirrors 14A in the X-axis direction and the Y-axis direction attached to the galvanometer 14. The image is formed or erased.
The fθ lens 16 is a lens that causes the laser light rotationally scanned at a constant angular speed by a mirror 14A attached to the galvanometer 14 to move at a constant speed on the plane of the thermoreversible recording medium.

The power supply control unit includes a discharge power supply (in the case of a CO ₂ laser) or a drive power supply for a light source that excites a laser medium (such as a YAG laser), a drive power supply for a galvanometer, a cooling power supply for a Peltier element, and the like. It is composed of a control unit that controls the control.

  The program unit is a unit for inputting conditions such as the intensity of laser light and the speed of laser scanning, and creating and editing characters to be recorded in order to form or erase an image by touch panel input or keyboard input. .

  The laser irradiation unit, that is, the image recording / erasing head portion is mounted on an image processing apparatus. In addition to the above, the image processing apparatus includes a transport unit and a control unit for the thermoreversible recording medium. Naturally, it has a monitor unit (touch panel) and the like.

The image processing method and the image processing apparatus of the present invention can repeatedly form and erase a high-contrast image at high speed on a thermoreversible recording medium such as a label affixed to a container such as cardboard in a non-contact manner. In addition, deterioration of the thermoreversible recording medium due to repetition can be suppressed. For this reason, it can be particularly suitably used in a distribution / delivery system. In this case, for example, an image can be formed and erased on the label while moving the cardboard placed on a belt conveyor, and the shipping time can be shortened because the line does not need to be stopped. Further, the cardboard to which the label is attached can be reused as it is without peeling off the label, and the image can be erased and recorded again.
In addition, since the image processing apparatus includes the light irradiation intensity adjusting unit that changes the light irradiation intensity of the laser light, it effectively suppresses deterioration of the thermoreversible recording medium due to repeated image formation and erasure. be able to.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

(Example 1)
The present embodiment is an embodiment corresponding to the first aspect of the image processing method of the present invention.
<Preparation of thermoreversible recording medium>
A thermoreversible recording medium in which the color tone reversibly changes depending on temperature (transparent state-colored state) was produced as follows.

-Support-
As a support, a 125 μm thick white turbid polyester film (manufactured by Teijin DuPont Co., Ltd., Tetron film U2L98W) was used.

-Under layer-
30 parts by mass of a styrene-butadiene copolymer (manufactured by Nippon A & L Co., PA-9159), 12 parts by mass of a polyvinyl alcohol resin (manufactured by Kuraray Co., Ltd., Poval PVA103), hollow particles (manufactured by Matsumoto Yushi Co., Ltd., Microsphere R) -300) 20 parts by mass and 40 parts by mass of water were added and stirred for about 1 hour until a uniform state was obtained to prepare an under layer coating solution.
Next, the obtained under layer coating solution was applied onto the support with a wire bar, and heated and dried at 80 ° C. for 2 minutes to form an under layer having a thickness of 20 μm.

-Reversible thermosensitive recording layer (recording layer)-
5 parts by mass of a reversible developer represented by the following structural formula (1) and 0.5 parts by mass of two types of decoloring accelerators represented by the following structural formulas (2) and (3) 10 parts by weight of a polyol 50% by weight solution (hydroxyl value: 200) and 80 parts by weight of methyl ethyl ketone were pulverized and dispersed using a ball mill until the average particle size was about 1 μm.

(Reversible developer)

(Discoloring accelerator)

  Next, 1 part by mass of 2-anilino-3-methyl-6dibutylaminofluorane as the leuco dye is represented by the following structural formula (4) in a dispersion obtained by pulverizing and dispersing the reversible developer. 0.2 parts by mass of a phenolic antioxidant (Ciba Specialty Chemicals, IRGANOX565), 0.03 parts by weight of a photothermal conversion material (Nexcatalyst Co., Ltd., e-color IR-14), and isocyanate (Nippon Polyurethane Co., Ltd.) 5 parts by mass of Coronate HL (manufactured by company) was added and stirred well to prepare a recording layer coating solution.

  Next, the obtained recording layer coating solution was applied onto the support on which the under layer had been formed using a wire bar, dried at 100 ° C. for 2 minutes, and then cured at 60 ° C. for 24 hours. As a result, a recording layer having a thickness of about 11 μm was formed.

-Intermediate layer-
Acrylic polyol resin 50 mass% solution (Mitsubishi Rayon Co., Ltd., LR327) 3 mass parts, Zinc oxide fine particle 30 mass% dispersion (Sumitomo Cement Co., Ltd., ZS303) 7 mass parts, Isocyanate (Nihon Polyurethane Co., Ltd., Coronate HL) 1.5 parts by mass and 7 parts by mass of methyl ethyl ketone were added and stirred well to prepare an intermediate layer coating solution.
Next, on the support on which the under layer and the recording layer are formed, the intermediate layer coating solution is applied with a wire bar, heated and dried at 90 ° C. for 1 minute, and then at 60 ° C. Heating was performed for 2 hours to form an intermediate layer having a thickness of about 2 μm.

-Protective layer-
3 parts by mass of pentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA), 3 parts by mass of urethane acrylate oligomer (manufactured by Negami Kogyo Co., Ltd., Art Resin UN-3320HA), acrylic ester of dipentaerythritol caprolactone ( Nippon Kayaku Co., Ltd., KAYARAD DPCA-120) 3 parts by mass, silica (Mizusawa Chemical Co., Ltd., P-526) 1 part by mass, photopolymerization initiator (Ciba Geigy Japan, Irgacure 184) 0.5 Part by mass and 11 parts by mass of isopropyl alcohol were added, and the mixture was well stirred by a ball mill and dispersed until the average particle size became about 3 μm to prepare a coating solution for a protective layer.
Next, on the support on which the under layer, the recording layer, and the intermediate layer are formed, the protective layer coating solution is applied with a wire bar, heated and dried at 90 ° C. for 1 minute, The film was crosslinked with an 80 W / cm ultraviolet lamp to form a protective layer having a thickness of about 4 μm.

-Back layer-
Pentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA) 7.5 parts by mass, urethane acrylate oligomer (manufactured by Negami Kogyo Co., Ltd., Art Resin UN-3320HA) 2.5 parts by mass, acicular conductive titanium oxide ( FT-3000 manufactured by Ishihara Sangyo Co., Ltd., long axis = 5.15 μm, short axis = 0.27 μm, composition: 2.5 parts by mass of titanium oxide coated with antimony-doped tin oxide, photopolymerization initiator (Nippon Ciba-Geigy Corporation) Manufactured, Irgacure 184) and 0.5 parts by mass of isopropyl alcohol and 13 parts by mass of isopropyl alcohol were added, and the mixture was thoroughly stirred with a ball mill to prepare a coating solution for a back layer.
Next, the back layer coating solution is applied with a wire bar onto the surface of the support on which the recording layer, the intermediate layer, and the protective layer are formed, on the side where these layers are not formed. After heating and drying at 90 ° C. for 1 minute, crosslinking was performed with an 80 W / cm ultraviolet lamp to form a back layer having a thickness of about 4 μm.
Thus, a thermoreversible recording medium was produced.

<Image forming process>
As a laser, a 140 W fiber coupling type high-power semiconductor laser device equipped with a condensing optical system f100 (manufactured by Yena Optic, NBT-S140mkII, center wavelength: 808 nm, optical fiber core diameter: 600 μm, NA: 0.22) Was adjusted so that the laser output was 12 W, the irradiation distance was 91.4 mm, and the spot diameter was about 0.6 mm. The thermoreversible recording medium was irradiated with laser light at an XY stage feed rate of 1,200 mm / s to form a linear image.
At this time, the light is attenuated by using five ND filters (“NG10”; manufactured by Dumas Optronics) so that the laser output is 0.01% or less, and is approximately in the laser beam traveling direction. When the light intensity distribution in the cross section in the orthogonal direction was measured using a laser beam profiler BeamOn (manufactured by Dumas Optronics), the light intensity distribution curve shown in FIG. 8 was obtained. Further, a differential curve obtained by performing the first derivative (X ′) and the second derivative (X ″) of the light intensity distribution curve is represented by FIG. 1B. It was found that the light irradiation intensity was 1.05 times.

<Image erasing process>
Subsequently, using the laser device, the laser output was adjusted to 15 W, the irradiation distance was 86 mm, and the spot diameter was 3.0 mm, and formed on the thermoreversible recording medium at an XY stage feed rate of 1,200 mm / s. The linear image was erased.
At this time, similarly, the light intensity distribution in the cross section in the direction substantially perpendicular to the traveling direction of the laser beam in the laser beam was measured using a laser beam profiler BeamOn (manufactured by Dumas Optronics), and as shown in FIG. A light intensity distribution curve was obtained. Moreover, the differential curve obtained by differentiating the light intensity distribution curve once (X ′) and twice (X ″) is shown in FIG. 1D. It was found that the light irradiation intensity was 0.6 times.

  When the image forming step and the image erasing step were repeated 100 times under the above conditions, uniform image formation and erasing could be performed.

(Example 2)
The present embodiment is an embodiment corresponding to the first aspect of the image processing method of the present invention.
<Image forming process>
Using the fiber coupling type high-power semiconductor laser device of Example 1, the laser output was adjusted to 25 W, the irradiation distance was 88.0 mm, and the spot diameter was 2.0 mm. The thermoreversible recording medium produced in Example 1 was irradiated with laser light at an XY stage feed rate of 1,200 mm / s to form a linear image.
At this time, in the same manner as in Example 1, the light was attenuated using five ND filters so that the laser output was 0.01% or less, and substantially orthogonal to the traveling direction of the laser light in the laser light. When the light intensity distribution in the cross section in the direction was measured in the same manner as in Example 1, the light intensity distribution curve shown in FIG. 9 was obtained. Moreover, the differential curve obtained by differentiating the light intensity distribution curve once (X ′) and twice (X ″) is shown in FIG. 1D. It was found that the light irradiation intensity was 0.7 times.

<Image erasing process>
Subsequently, the linear image formed on the thermoreversible recording medium was erased using the laser device under the same conditions as in Example 1.

  When the image forming step and the image erasing step were repeated 300 times under the above conditions, uniform image formation and erasing could be performed.

(Example 3)
The present embodiment is an embodiment corresponding to the first aspect of the image processing method of the present invention.
<Image forming process>
Using the fiber coupling type high-power semiconductor laser device of Example 1, the laser output was adjusted to 35 W, the irradiation distance was 86.0 mm, and the spot diameter was 3.0 mm. The thermoreversible recording medium produced in Example 1 was irradiated with laser light at an XY stage feed rate of 1,200 mm / s to form a linear image.
At this time, in the same manner as in Example 1, the light was attenuated using five ND filters so that the laser output was 0.01% or less, and substantially orthogonal to the traveling direction of the laser light in the laser light. When the light intensity distribution in the cross section in the direction was measured in the same manner as in Example 1, the light intensity distribution curve shown in FIG. 10 was obtained. Moreover, the differential curve obtained by differentiating the light intensity distribution curve once (X ′) and twice (X ″) is shown in FIG. 1D. It was found that the light irradiation intensity was 0.6 times.

<Image erasing process>
Subsequently, the linear image formed on the thermoreversible recording medium was erased using the laser device under the same conditions as in Example 1.

  When the image forming step and the image erasing step were repeated 300 times under the above conditions, uniform image formation and erasing could be performed.

(Example 4)
The present embodiment is an embodiment corresponding to the first aspect of the image processing method of the present invention.
<Preparation of thermoreversible recording medium>
In Example 1, a thermoreversible recording medium was produced in the same manner as in Example 1 except that the photothermal conversion material was not used when producing the thermoreversible recording medium.

<Image forming process>
A laser marker (LP-440, manufactured by Sunkus Co., Ltd.) equipped with a CO ₂ laser with an output of 40 W was used, and a mask for cutting the central portion of the laser light was incorporated in the optical path of the laser light. Then, in the light intensity distribution in the cross section in the direction substantially perpendicular to the traveling direction of the laser light in the laser light, the light irradiation intensity in the central part was adjusted to be 0.5 times the light irradiation intensity in the peripheral part. .
Next, the laser marker is used to adjust the laser output to 6.5 W, the irradiation distance of 185 mm, the spot diameter of 0.18 mm, and the scan speed of 1,000 mm / s. Light was irradiated to form a linear image.

<Image erasing process>
Subsequently, the mask for cutting the center portion of the laser beam was removed from the optical path of the laser marker, and the laser output was adjusted to 22 W, the irradiation distance was 155 mm, the spot diameter was about 2 mm, and the scan speed was 3,000 mm / s. . Then, the image formed on the thermoreversible recording medium was erased.

  When the image forming step and the image erasing step were repeated 300 times under the above conditions, uniform image formation and erasing could be performed.

(Example 5)
The present embodiment is an embodiment corresponding to the first aspect of the image processing method of the present invention.
<Preparation of thermoreversible recording medium>
A thermoreversible recording medium in which the transparency changes reversibly (transparent state-white turbid state) depending on the temperature was produced as follows.

-Support-
As a support, a transparent PET film having a thickness of 175 μm (Lumirror 175-T12, manufactured by Toray Industries, Inc.) was used.

-Reversible thermosensitive recording layer (recording layer)-
3 parts by mass of an organic low molecular weight substance represented by the following structural formula (5) in a resin solution obtained by dissolving 26 parts by mass of vinyl chloride copolymer (manufactured by ZEON Corporation, M110) in 210 parts by mass of methyl ethyl ketone And 7 parts by mass of docosyl behenate were added, ceramic beads having a diameter of 2 mm were placed in a glass bottle, and dispersed for 48 hours using a paint shaker (manufactured by Asada Tekko Co., Ltd.) to prepare a uniform dispersion.

(Organic low molecular weight substance)

Next, 0.07 part by weight of a light-to-heat conversion material (manufactured by Nippon Shokubai Co., Ltd., EEX Color IR-14) and 4 parts by weight of an isocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., Coronate 2298-90T) are added to the obtained dispersion. Then, a thermal recording layer solution was prepared.
Next, the obtained heat-sensitive recording layer solution is applied onto the support (adhesive layer of a PET film having a magnetic recording layer), heated and dried, and then stored in a 65 ° C. environment for 24 hours. And a thermosensitive recording layer having a thickness of about 10 μm was provided.

-Protective layer-
A heat-sensitive recording layer containing a solution of 10 parts by mass of a 75% butyl acetate solution of urethane acrylate UV curable resin (Unidic C7-157, manufactured by Dainippon Ink & Chemicals, Inc.) and 10 parts by mass of isopropyl alcohol with a wire bar. After coating on the top, heating and drying, it was cured by irradiating with an ultraviolet ray with an 80 w / cm high-pressure mercury lamp to form a protective layer having a thickness of about 3 μm.
Thus, a thermoreversible recording medium was produced.

Using the fiber coupling type high power semiconductor laser device of Example 1, the laser output was adjusted to 20 W, the irradiation distance was 88.0 mm, and the spot diameter was 2.0 mm. The produced thermoreversible recording medium was irradiated with laser light at an XY stage feed rate of 1,200 mm / s to form a linear image.
At this time, in the same manner as in Example 1, the light was attenuated using five ND filters so that the laser output was 0.01% or less. When the light intensity distribution in the cross section in the direction substantially perpendicular to the traveling direction of the laser light in the laser light was measured in the same manner as in Example 1, the light intensity distribution curve shown in FIG. As a result, it was found that the light irradiation intensity at the central part was 0.7 times the light irradiation intensity at the peripheral part.

<Image erasing process>
Subsequently, the laser device was used to adjust the laser output to 12 W, the irradiation distance of 86 mm, and the spot diameter of 3.0 mm, and the XY stage was fed onto the thermoreversible recording medium at a feed rate of 1,200 mm / s. The linear image was erased.

  When the image forming step and the image erasing step were repeated 300 times under the above conditions, uniform image formation and erasing could be performed.

(Example 6)
The present embodiment is an embodiment corresponding to the first aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Example 4, adjustment was made so that the laser output was 10.4 W, the irradiation distance was 195 mm, the line width was 0.5 mm, the spot diameter was about 0.9 mm, and the scan speed was 1,000 mm / s. The thermoreversible recording medium prepared in 4 was irradiated with laser light to form a linear image.
At this time, the light intensity distribution in the cross section substantially perpendicular to the traveling direction of the laser light at this time is such that the light irradiation intensity at the central part is 1.04 times the light irradiation intensity at the peripheral part. It was an intensity distribution.

<Image erasing process>
Subsequently, using the laser marker, a linear image formed on the thermoreversible recording medium is adjusted so that the laser output is 22 W, the irradiation distance is 155 mm, the spot diameter is about 2 mm, and the scan speed is 3,000 mm / s. Deleted.

  When the image forming step and the image erasing step were repeated 100 times under the above conditions, uniform image formation and erasing could be performed.

(Example 7)
The present embodiment is an embodiment corresponding to the first aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Example 4, the laser output was adjusted to 16.0 W, the irradiation distance was 200 mm, the line width was 0.7 mm, the spot diameter was about 1.3 mm, and the scan speed was 1,000 mm / s. The thermoreversible recording medium prepared in 4 was irradiated with laser light to form a linear image.
At this time, the light intensity distribution in the cross section substantially perpendicular to the traveling direction of the laser light at this time is such that the light irradiation intensity at the central part is 1.03 times the light irradiation intensity at the peripheral part. It was an intensity distribution.

<Image erasing process>
Subsequently, using the laser marker, a linear image formed on the thermoreversible recording medium is adjusted so that the laser output is 22 W, the irradiation distance is 155 mm, the spot diameter is about 2 mm, and the scan speed is 3,000 mm / s. Deleted.

  When the image forming step and the image erasing step were repeated 200 times under the above conditions, a uniform image could be formed and erased.

(Example 8)
The present embodiment is an embodiment corresponding to the first aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Example 4, the laser output was 7.5 W, the irradiation distance was 195 mm, the line width was 0.5 mm, the spot diameter was about 1.3 mm, and the scan speed was 1,000 mm / s. The thermoreversible recording medium prepared in 5 was irradiated with laser light to form a linear image.
The light intensity distribution in the cross section in the direction substantially perpendicular to the traveling direction of the laser light at this time was the same as that in Example 6.

<Image erasing process>
Subsequently, a linear image formed on the thermoreversible recording medium is adjusted using the laser marker so that the laser output is 13 W, the irradiation distance is 155 mm, the spot diameter is about 2 mm, and the scanning speed is 3,000 mm / s. Deleted.

  When the image forming step and the image erasing step were repeated 200 times under the above conditions, a uniform image could be formed and erased.

Example 9
The present embodiment is an embodiment corresponding to the first aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Example 4 and the thermoreversible recording medium, a linear image was formed in the same manner as in Example 4.

<Image erasing process>
Subsequently, the image was erased by heating at 140 ° C. for 1 second at a pressure of 1 kgf / cm ² using a thermal tilt tester (TYPE HG-100 manufactured by Toyo Seiki Co., Ltd.).

  When the image forming step and the image erasing step were repeated 300 times under the above conditions, uniform image formation and erasing could be performed.

(Comparative Example 1)
This comparative example is a comparative example for the first aspect of the image processing method of the present invention.
<Image forming process>
Using the fiber coupling type high-power semiconductor laser device of Example 1, the laser output was adjusted to 12 W, the irradiation distance was 92.0 mm, and the spot diameter was about 0.6 mm. The thermoreversible recording medium produced in Example 1 was irradiated with laser light at an XY stage feed rate of 1,200 mm / s to form a linear image.
When the light intensity distribution in the cross section in the direction substantially orthogonal to the traveling direction of the laser light at this time was measured using a laser beam profiler BeamOn (manufactured by Dumas Optronics), the light intensity distribution shown in FIG. A curve was obtained. Moreover, the differential curve obtained by differentiating the light intensity distribution curve once (X ′) and twice (X ″) is shown in FIG. 1E. It was found that the light irradiation intensity was 1.3 times.

<Image erasing process>
Subsequently, the image was erased by heating at 140 ° C. for 1 second at a pressure of 1 kgf / cm ² using a thermal tilt tester (TYPE HG-100 manufactured by Toyo Seiki Co., Ltd.).

  When the image forming step and the image erasing step were repeated under the above conditions, a portion that could not be erased occurred in the central portion of the linear image after 30 times.

(Comparative Example 2)
This comparative example is a comparative example for the first aspect of the image processing method of the present invention.
<Image forming process>
Using a laser marker equipped with a CO ₂ laser of 40 W output (manufactured by Sunkus Corporation, LP-440), laser output 4.7 W, irradiation distance 185 mm, spot diameter of about 0.2 mm, scan speed 1,000 mm / s The thermoreversible recording medium produced in Example 4 was irradiated with a laser beam to form a linear image.
When the light intensity distribution in the cross section in the direction substantially orthogonal to the traveling direction of the laser light at this time was measured using a high power beam beam analyzer LPK-CO2-16 (manufactured by Spiricon), The light intensity distribution was such that the light irradiation intensity at the center was 1.25 times the light irradiation intensity at the center.

<Image erasing process>
Subsequently, the image was erased by heating at 140 ° C. for 1 second at a pressure of 1 kgf / cm ² using a thermal tilt tester (TYPE HG-100 manufactured by Toyo Seiki Co., Ltd.).

  When the image forming step and the image erasing step were repeated under the above conditions, a portion that could not be erased occurred at the center of the linear image after 50 times.

(Comparative Example 3)
This comparative example is a comparative example for the first aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Comparative Example 2 and the thermoreversible recording medium, a linear image was formed in the same manner as in Comparative Example 2.
At this time, the light intensity distribution in the cross section substantially orthogonal to the traveling direction of the laser light at this time is such that the light irradiation intensity at the central part is 1.25 times the light irradiation intensity at the peripheral part. It was an intensity distribution.

<Image erasing process>
Subsequently, using the laser marker, the laser output was adjusted to 2.0 W, the irradiation distance was 185 mm, the spot diameter was 0.18 mm, and the scan speed was 2,500 mm / s. Then, the laser beam is scanned linearly, and 20 laser beams are scanned linearly and in parallel so as to have an interval of 0.01 mm in a direction substantially perpendicular to the scanning direction, and the thermoreversible recording medium is formed. The formed linear image was erased.
At this time, the light intensity distribution in the cross section in the direction substantially perpendicular to the traveling direction of the laser light in the laser light at this time was the same as the light intensity distribution in the image forming step.

  When the image forming step and the image erasing step were repeated under the above conditions, a portion that could not be erased occurred at the center of the linear image after 50 times.

(Example 10)
The present embodiment is an embodiment corresponding to the second aspect of the image processing method of the present invention.
<Image forming process>
Using a laser marker (LP-440 manufactured by Sunkus Co., Ltd.) equipped with a CO ₂ laser with an output of 40 W, a laser output of 4.7 W, an irradiation distance of 185 mm, a spot diameter of 0.18 mm, and a scan speed of 1,000 mm / s It adjusted so that it might become. Then, the thermoreversible recording medium produced in Example 4 was irradiated with a laser beam to form a linear image in a range of 10 mm × 50 mm.

<Image erasing process>
Thereafter, the laser output was adjusted to 32 W, the irradiation distance was 224 mm, the spot diameter was 3.0 mm (17 times the spot diameter at the time of image formation in the image forming process), and the scan speed was 4,500 mm / s. Then, the laser beam is scanned linearly, and 34 laser beams are scanned linearly and in parallel so as to have an interval of 0.30 mm corresponding to 1/10 of the spot diameter in a direction substantially orthogonal to the scanning direction. Then, irradiation was performed within a range of 10 mm × 50 mm. When the image density was measured using a Macbeth densitometer RD914, the density of the image erasing area was 0.09. As shown in FIG. 12, the image formed on the thermoreversible recording medium can be completely erased. there were. The image erasing time at this time was 0.53 seconds.
Subsequently, the thermoreversible recording medium on which the image has been formed in the image forming process is attached to a plastic box, placed on a conveyor and moved at a conveying speed of 13 m / min, under the erasing conditions in the image erasing process. When the image was erased, the movement time of the thermoreversible recording medium was 0.59 seconds, and an image in the range of 10 mm × 50 mm could be completely erased.

(Example 11)
The present embodiment is an embodiment corresponding to the second aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker and the thermoreversible recording medium of Example 10 and irradiating the thermoreversible recording medium with laser light in the same manner as in Example 6, a linear image is formed in a range of 10 mm × 50 mm. did.

<Image erasing process>
Thereafter, the laser output was adjusted to 32 W, the irradiation distance was 224 mm, the spot diameter was 3.0 mm, and the scan speed was 3,200 mm / s. Then, the laser beam is scanned linearly, and 23 laser beams are scanned linearly and in parallel so that the interval is 0.43 mm corresponding to 1/7 of the spot diameter in a direction substantially orthogonal to the scanning direction. Then, irradiation was performed within a range of 10 mm × 50 mm. When the image density was measured using a Macbeth densitometer RD914, the density of the image erasing area was 0.09, and the image formed on the thermoreversible recording medium was completely erasable. The erase time at this time was 0.51 seconds.

Example 12
The present embodiment is an embodiment corresponding to the second aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Example 10 and the thermoreversible recording medium, the thermoreversible recording medium is irradiated with laser light in the same manner as in Example 10 to form a linear image in a range of 10 mm × 50 mm. did.

<Image erasing process>
Thereafter, the laser output was adjusted to 32 W, the irradiation distance was 224 mm, the spot diameter was 3.0 mm, and the scan speed was 2,600 mm / s. Then, the laser beam is scanned linearly, and 17 laser beams are scanned linearly and in parallel so that an interval of 0.60 mm corresponding to 1/5 of the spot diameter is obtained in a direction substantially orthogonal to the scanning direction. Then, irradiation was performed within a range of 10 mm × 50 mm. When the image density was measured using a Macbeth densitometer RD914, the density of the image erasing area was 0.09, and the image formed on the thermoreversible recording medium was completely erasable. The erase time at this time was 0.43 seconds.

(Example 13)
The present embodiment is an embodiment corresponding to the second aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Example 10 and the thermoreversible recording medium, the thermoreversible recording medium is irradiated with laser light in the same manner as in Example 10 to form a linear image in a range of 10 mm × 50 mm. did.

<Image erasing process>
Thereafter, the laser output was adjusted to 32 W, the irradiation distance was 224 mm, the spot diameter was 3.0 mm, and the scan speed was 2,400 mm / s. Then, the laser beam is scanned linearly, and 14 laser beams are scanned linearly and in parallel so that the interval is 0.75 mm corresponding to ¼ of the spot diameter in a direction substantially orthogonal to the scanning direction. Then, irradiation was performed within a range of 10 mm × 50 mm. When the image density was measured using a Macbeth densitometer RD914, the density of the image erasing area was 0.09, and the image formed on the thermoreversible recording medium was completely erasable. The erase time at this time was 0.38 seconds.

(Example 14)
The present embodiment is an embodiment corresponding to the second aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker and the thermoreversible recording medium of Example 4, the thermoreversible recording medium is irradiated with laser light in the same manner as in Example 4 to form a linear image in a range of 10 mm × 50 mm. did.

<Image erasing process>
Thereafter, the mask for cutting the central portion of the laser beam was removed from the optical path of the laser marker, and the laser beam was irradiated within a range of 10 mm × 50 mm in the same manner as the image erasing process of Example 13. When the image density was measured using a Macbeth densitometer RD914, the density of the image erasing area was 0.09, and the image formed on the thermoreversible recording medium was completely erasable. The erase time at this time was 0.38 seconds.

  When the image forming step and the image erasing step were repeated 300 times under the above conditions, uniform image formation and uniform erasing in a short time could be performed.

(Example 15)
The present embodiment is an embodiment corresponding to the second aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Example 10 and the thermoreversible recording medium, the thermoreversible recording medium is irradiated with laser light in the same manner as in Example 10 to form a linear image in a range of 10 mm × 50 mm. did.

<Image erasing process>
Thereafter, the laser output was adjusted to 32 W, the irradiation distance was 204 mm, the spot diameter was 1.6 mm (9 times the spot diameter at the time of image formation in the image forming step), and the scan speed was 8,000 mm / s. Then, the laser beam was scanned in a straight line, and 50 laser beams were scanned linearly and in parallel at intervals of 0.20 mm in a direction substantially orthogonal to the scanning direction, and irradiated within a range of 10 mm × 50 mm. However, the image was completely erasable. Further, the image erasing time at this time was 0.63 seconds.

(Example 16)
The present embodiment is an embodiment corresponding to the second aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Example 10 and the thermoreversible recording medium, the thermoreversible recording medium is irradiated with laser light in the same manner as in Example 10 to form a linear image in a range of 10 mm × 50 mm. did.

<Image erasing process>
Thereafter, the laser output was adjusted to 32 W, the irradiation distance was 207 mm, the spot diameter was 1.8 mm (10 times the spot diameter during image formation in the image forming step), and the scan speed was 7,500 mm / s. Then, the laser beam is scanned in a straight line, and 45 laser beams are scanned linearly and in parallel at intervals of 0.23 mm in a direction substantially orthogonal to the scanning direction and irradiated within a range of 10 mm × 50 mm. The image was completely erasable. The erase time at this time was 0.55 seconds.

(Example 17)
The present embodiment is an embodiment corresponding to the second aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Example 10 and the thermoreversible recording medium, the thermoreversible recording medium is irradiated with laser light in the same manner as in Example 10 to form a linear image in a range of 10 mm × 50 mm. did.

<Image erasing process>
Thereafter, the laser output was adjusted to 32 W, the irradiation distance was 265 mm, the spot diameter was 6.0 mm (33 times the spot diameter at the time of image formation in the image forming process), and the scan speed was 1,600 mm / s. Then, the laser beam is scanned in a straight line, and 14 laser beams are scanned linearly and in parallel at intervals of 0.75 mm in a direction substantially orthogonal to the scanning direction and irradiated within a range of 10 mm × 50 mm. The image was completely erasable. Further, the image erasing time at this time was 0.53 seconds.

( Reference Example 1 )
< Image forming process>
Using the laser marker of Example 10 and the thermoreversible recording medium, the thermoreversible recording medium is irradiated with laser light in the same manner as in Example 10 to form a linear image in a range of 10 mm × 50 mm. did.

<Image erasing process>
Thereafter, the laser output was adjusted to 32 W, the irradiation distance was 279 mm, the spot diameter was 7.0 mm (38.9 times the spot diameter during image formation in the image forming step), and the scan speed was 1,000 mm / s. Then, the laser beam is scanned in a straight line, and 12 laser beams are scanned linearly and in parallel at intervals of 0.88 mm in a direction substantially perpendicular to the scanning direction and irradiated within a range of 10 mm × 50 mm. The image was completely erasable. Further, the image erasing time at this time was 0.71 seconds.

  Subsequently, the thermoreversible recording medium on which the image has been formed in the image forming process is attached to a plastic box, placed on a conveyor and moved at a conveying speed of 13 m / min, under the erasing conditions in the image erasing process. When the image was erased, the moving time of the thermoreversible recording medium was 0.59 seconds, and thus an image in the range of 10 mm × 50 mm could not be completely erased.

Example 19
The present embodiment is an embodiment corresponding to the second aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker and the thermoreversible recording medium of Example 10, the laser output was 14 W, the irradiation distance was 200 mm, the spot diameter was 1.3 mm, and the scan speed was 1,000 mm / s. The thermoreversible recording medium was irradiated with laser light to form a linear image in a range of 10 mm × 50 mm.

<Image erasing process>
Thereafter, the laser output was adjusted to 32 W, the irradiation distance was 200 mm, the spot diameter was 1.3 mm (1.0 times the spot diameter during image formation in the image forming step), and the scan speed was 11,000 mm / s. Then, the laser beam is scanned in a straight line, and 63 laser beams are scanned linearly and in parallel at intervals of 0.16 mm in a direction substantially perpendicular to the scanning direction and irradiated within a range of 10 mm × 50 mm. The image was completely erasable. Further, the image erasing time at this time was 0.63 seconds.

  Subsequently, the thermoreversible recording medium on which the image has been formed in the image forming process is attached to a plastic box, placed on a conveyor and moved at a conveying speed of 13 m / min, under the erasing conditions in the image erasing process. When the image was erased, the moving time of the thermoreversible recording medium was 0.59 seconds, and thus an image in the range of 10 mm × 50 mm could not be completely erased.

(Example 20)
The present embodiment is an embodiment corresponding to the second aspect of the image processing method of the present invention.
<Preparation of thermoreversible recording medium>
In Example 5, a thermoreversible recording medium was produced in the same manner as in Example 5 except that the photothermal conversion material was not used when producing the thermoreversible recording medium.

<Image forming process>
Using a laser marker equipped with a CO ₂ laser with an output of 40 W (manufactured by Sunkus Co., Ltd., LP-440), a laser output of 3.2 W, an irradiation distance of 185 mm, a spot diameter of 0.18 mm, and a scan speed of 1,000 mm / s It adjusted so that it might become. And the laser beam was irradiated with respect to the produced thermoreversible recording medium, and the linear image was formed in the range of 10 mm x 50 mm.

<Image erasing process>
Thereafter, the laser output was adjusted to 17 W, the irradiation distance was 224 mm, the spot diameter was 3.0 mm, and the scan speed was 2,400 mm / s. Then, the laser beam is scanned linearly, and 17 laser beams are scanned linearly and in parallel so that an interval of 0.60 mm corresponding to 1/5 of the spot diameter is obtained in a direction substantially orthogonal to the scanning direction. Then, irradiation was performed within a range of 10 mm × 50 mm. When the image density was measured using a Macbeth densitometer RD914 with black paper (OD 2.0) on the back side, the density of the image erasure area was 1.60 and formed on the thermoreversible recording medium. The image was completely erasable. The erase time at this time was 0.43 seconds.

(Comparative Example 4)
This comparative example is a comparative example for the second aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Example 10 and the thermoreversible recording medium, the thermoreversible recording medium is irradiated with laser light in the same manner as in Example 10 to form a linear image in a range of 10 mm × 50 mm. did.

<Image erasing process>
Thereafter, the laser output was adjusted to 32 W, the irradiation distance was 224 mm, the spot diameter was 3.0 mm, and the scan speed was 6,000 mm / s. Then, the laser beam is scanned linearly, and 50 laser beams are scanned linearly and in parallel so as to be 0.20 mm intervals corresponding to 1/15 of the spot diameter in a direction substantially orthogonal to the scanning direction. Then, irradiation was performed within a range of 10 mm × 50 mm. When the image density was measured using a Macbeth densitometer RD914, the density of the image erasure area was 0.09, and the image formed on the thermoreversible recording medium was completely erasable. The time was 0.68 seconds and took a long time. For this reason, the thermoreversible recording medium on which the image is formed in the image forming process is attached to a plastic box, placed on a conveyor and moved at a conveying speed of 13 m / min, and under the erasing conditions in the image erasing process. When the image was erased, the movement time of the thermoreversible recording medium was 0.59 seconds, and the image in the range of 10 mm × 50 mm could not be completely erased.

(Comparative Example 5)
This comparative example is a comparative example for the second aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Example 10 and the thermoreversible recording medium, the thermoreversible recording medium is irradiated with laser light in the same manner as in Example 10 to form a linear image in a range of 10 mm × 50 mm. did.

<Image erasing process>
Thereafter, the laser power was adjusted to 32 W, the irradiation distance was 224 mm, the spot diameter was 3.0 mm, and the scan speed was 1,600 mm / s. Then, the laser beam is scanned in a straight line, and in a direction substantially perpendicular to the scanning direction, seven laser beams are scanned linearly and in parallel so as to have an interval of 1.5 mm corresponding to 1/2 of the spot diameter. Then, irradiation was performed within a range of 10 mm × 50 mm. When the image density was measured using a Macbeth densitometer RD914, the density of the image erasure area was 0.13, and as shown in FIG. 13, the image could not be completely erased. The erase time at this time was 0.27 seconds.

(Example 21)
The present embodiment is an embodiment corresponding to the third aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker of Example 10 and the thermoreversible recording medium, a laser beam was scanned 100 mm linearly under the same laser conditions as in Example 10, and an interval of 60 seconds in a direction substantially perpendicular to the scanning direction Then, three laser beams were scanned linearly and in parallel so as to have an interval of 0.15 mm. At this time, the irradiation region of the second laser beam overlaps the irradiation region of the first laser beam, and the irradiation region of the third laser beam overlaps the irradiation region of the second laser beam. Scanned. As a result, a uniform image having a width of 100 mm × 0.5 mm could be formed without reducing the image density at the overlapping portion of the laser light irradiation region (during the laser light scanning).
Also, after scanning the first laser beam linearly under the above laser conditions, 60 seconds later, the first laser beam was scanned under the same laser conditions in the direction perpendicular to the scanning direction of the first laser beam. The second laser beam was scanned linearly so as to overlap the irradiation region. When the image density at the intersection of these laser light irradiation areas was measured using a Macbeth densitometer RD914, the image density was 1.53. As shown in FIG. 14, the portion erased at the intersection Did not exist.

(Example 22)
The present embodiment is an embodiment corresponding to the third aspect of the image processing method of the present invention.
<Image forming process>
Using the laser marker and the thermoreversible recording medium of Example 4, the laser beam was scanned 100 mm linearly in the same manner as in Example 21 under the same laser conditions as in the image forming process of Example 4, and the scanning direction 3 laser beams were scanned linearly and in parallel so as to obtain an interval of 0.15 mm at intervals of 60 seconds. As a result, a uniform image having a width of 100 mm × 0.5 mm could be formed without reducing the image density at the overlapping portion of the laser light irradiation region (during the laser light scanning).
Also, after scanning the first laser beam linearly under the above laser conditions, 60 seconds later, the first laser beam was scanned under the same laser conditions in the direction perpendicular to the scanning direction of the first laser beam. When the second laser beam was scanned linearly so as to overlap with the irradiation region, the portion erased at the intersection of these laser beam irradiation regions did not exist as in Example 21.

(Comparative Example 6)
This comparative example is a comparative example for the third aspect of the image processing method of the present invention.
<Image forming process>
In Example 21, after laser beam was scanned 100 nm linearly, the laser beam was linearly and parallelly spaced at intervals of 90 seconds in a direction substantially perpendicular to the scanning direction. An image was formed in the same manner as in Example 21 except that three lines were scanned. As a result, there was a portion where the image density was reduced in the overlapping portion of the laser light irradiation region (during the laser light scanning), and a uniform image could not be formed.
Further, after scanning the first laser beam linearly under the same laser condition as in Example 21, 90 seconds later, the laser beam was scanned in the direction perpendicular to the scanning direction of the first laser beam and the same laser condition as 1 The second laser beam was scanned linearly so as to overlap the irradiation region of the second laser beam. When the image density at the intersection of these laser light irradiation areas was measured using a Macbeth densitometer RD914, the image density was 0.10, and the portion erased at the intersection as shown in FIG. was there.

(Example 23)
The present embodiment is an embodiment corresponding to the third aspect of the image processing method of the present invention.
<Preparation of thermoreversible recording medium>
In the thermoreversible recording medium of Example 10, heat was changed in the same manner as in Example 10 except that the reversible developer in the recording layer was changed to a reversible developer represented by the following structural formula (6). A reversible recording medium was produced.

(Reversible developer)

<Image forming process>
An image was formed on the obtained thermoreversible recording medium using the laser marker of Example 10. The laser output was adjusted to 3.5 W, the irradiation distance was 185 mm, the spot diameter was about 0.2 mm, and the scan speed was 1,000 mm / s. Then, the laser beam was scanned 100 mm linearly, and three laser beams were scanned linearly and in parallel so as to be continuously spaced by 0.15 mm in a direction substantially orthogonal to the scanning direction. At this time, the irradiation region of the second laser beam overlaps the irradiation region of the first laser beam, and the irradiation region of the third laser beam overlaps the irradiation region of the second laser beam. Scanned. As a result, a uniform image having a width of 100 mm × 0.5 mm could be formed without reducing the image density at the overlapping portion of the laser light irradiation region (during the laser light scanning).
In addition, after scanning the first laser beam linearly under the laser conditions, 0.1 seconds later, the first laser beam is scanned in the direction perpendicular to the scanning direction of the first laser beam under the same laser conditions. The second laser beam was scanned linearly so as to overlap the laser beam irradiation region. When the image density at the intersection of these laser light irradiation areas was measured using a Macbeth densitometer RD914, the image density was 1.60, and there was no erased portion at the intersection.

(Comparative Example 7)
This comparative example is a comparative example for the third aspect of the image processing method of the present invention.
<Image forming process>
In Example 23, after linearly scanning the laser beam with a thickness of 100 nm, the laser is linearly and in parallel so that the interval is 0.15 mm at intervals of 0.2 seconds in a direction substantially orthogonal to the scanning direction. An image was formed in the same manner as in Example 23 except that three beams were scanned. As a result, there was a portion where the image density was reduced in the overlapping portion of the laser light irradiation region (during the laser light scanning), and a uniform image could not be formed.
Further, after performing the first laser scanning linearly under the same laser conditions as in Example 23, 0.2 seconds later, in the direction perpendicular to the scanning direction of the first laser light, under the same laser conditions, The second laser beam was scanned linearly so as to overlap the irradiation region of the first laser beam. When the image density at the intersection of these laser light irradiation areas was measured using a Macbeth densitometer RD914, the image density was 0.10, and there was an erased portion at the intersection.

(Example 24)
The present embodiment is an embodiment corresponding to the third aspect of the image processing method of the present invention.
<Image forming process>
An image was formed on the thermoreversible recording medium of Example 20 using the laser marker of Example 20. The laser output was adjusted to 3.2 W, the irradiation distance was 185 mm, the spot diameter was about 0.2 mm, and the scan speed was 1,000 mm / s. Then, the laser beam was scanned 100 mm linearly, and three laser beams were scanned linearly and in parallel so as to be continuously spaced by 0.15 mm in a direction substantially orthogonal to the scanning direction. At this time, the irradiation region of the second laser beam overlaps the irradiation region of the first laser beam, and the irradiation region of the third laser beam overlaps the irradiation region of the second laser beam. Scanned. As a result, a uniform image having a width of 100 mm × 0.5 mm could be formed without reducing the image density at the overlapping portion of the laser light irradiation region (during the laser light scanning).
In addition, after scanning the first laser beam linearly under the laser conditions, 0.1 seconds later, the first laser beam is scanned in the direction perpendicular to the scanning direction of the first laser beam under the same laser conditions. When the second laser beam was scanned linearly so as to overlap with the laser beam irradiation region, the erased portion did not exist at the intersection.

(Comparative Example 8)
This comparative example is a comparative example for the third aspect of the image processing method of the present invention.
<Image forming process>
In Example 24, after the laser beam was scanned 100 nm linearly, the laser was linearly and parallelly arranged at intervals of 0.2 seconds at intervals of 0.2 seconds in a direction substantially perpendicular to the scanning direction. An image was formed in the same manner as in Example 24 except that three beams were scanned. As a result, there was a portion where the image density was reduced in the overlapping portion of the laser light irradiation region (during the laser light scanning), and a uniform image could not be formed.
In addition, after scanning the first laser beam linearly under the above laser conditions, 0.2 seconds later, the first laser beam was scanned under the same laser conditions in the direction perpendicular to the scanning direction of the first laser beam. When the second laser beam was scanned linearly so as to overlap the light irradiation region, there was an erased portion at the intersection.

(Example 25)
This embodiment is an application example corresponding to the first aspect of the image processing method of the present invention.
<Production of label>
A label as the thermoreversible recording medium was produced as follows.
First, in the same manner as in Example 4, the under layer and the recording layer were sequentially formed on the support used in Example 4.

-Intermediate layer-
40 parts by mass solution of UV absorbing polymer (Otsuka Chemical Co., Ltd., PUVA-60MK-40K, hydroxyl value: 60) 20 parts by mass, xylene diisocyanate (Mitsui Takeda Chemical Co., Ltd., D-110N) 3.2 parts by mass And a composition comprising 23 parts by mass of methyl ethyl ketone (MEK) were sufficiently stirred by a ball mill to prepare a polymer-containing layer coating solution having an ultraviolet absorption structure.
Next, the obtained polymer-containing layer coating solution having an ultraviolet absorption structure was applied to the underlayer and the support on which the recording layer had been formed using a wire bar and dried at 90 ° C. for 1 minute. Then, it heated at 50 degreeC for 24 hours, and formed the polymer content layer (intermediate layer) which has a 2 micrometers film thickness UV absorption structure.

-Protective layer-
Next, a protective layer was formed in the same manner as in Example 4 on the produced intermediate layer.

-Adhesive layer-
Next, a composition composed of 50 parts by mass of an acrylic pressure-sensitive adhesive (manufactured by Toyo Ink Manufacturing Co., Ltd., BPS-1109) and 2 parts by mass of isocyanate (manufactured by Mitsui Takeda Chemical Co., D-170N) is sufficiently stirred, An adhesive layer coating solution was prepared.
The obtained adhesive layer coating solution is coated with a wire bar on the surface of the support on which the under layer, the recording layer, the intermediate layer, and the protective layer are not formed. And dried at 90 ° C. for 2 minutes to form an adhesive layer having a thickness of about 20 μm.
Thus, a thermoreversible recording label was produced.

<Image forming process and image erasing process>
The obtained thermoreversible recording label was cut into a size of 50 mm × 100 mm, attached to a plastic box, and image formation and erasure were carried out in the same manner as in Example 4 to form and erase a uniform image. And was able to do.

(Example 26)
This embodiment is an application example corresponding to the first aspect of the image processing method of the present invention.
<Production of tag (kanban)>
A tag (kanban) as the thermoreversible recording medium was produced as follows.
First, in the same manner as in Example 4, the recording layer, the intermediate layer, and the protective layer were sequentially formed on the support used in Example 4 to prepare a top sheet.
Next, in the same manner as in Example 4, only the back layer was formed on the support used in Example 4 to prepare a lower surface sheet.
The obtained sheet for the upper surface and the sheet for the lower surface were each cut into a size of 210 mm × 85 mm, and between these sheets, an RF-ID inlet (manufactured by DNP) and a PETG sheet (Mitsubishi) as an inlet peripheral spacer Resin Co., Ltd.) was sandwiched and bonded with an adhesive tape (Nitto Denko Co., Ltd.) to produce a thermoreversible recording tag (kanban) with a thickness of 500 μm and containing RF-ID.

<Image forming process and image erasing process>
When the obtained RF-ID-containing thermoreversible recording tag was attached to a plastic box and image formation and erasure were performed in the same manner as in Example 4, uniform image formation and erasure could be performed. It was.

(Experimental example 1)
In the same manner as in Example 10, a linear image was formed in a range of 10 mm × 50 mm. Next, the laser irradiation conditions are fixed at a laser output of 32 W, an irradiation distance of 224 mm, and a spot diameter of 3.0 mm, and the laser light irradiation position interval (to the irradiation spot diameter ratio) is 0.075 mm (1/40) to 1. The image was erased by appropriately changing within a range of 5 mm (1/2). FIG. 16 shows the relationship between the image erasing time and the laser light irradiation position interval (vs. irradiation spot diameter ratio).
In addition, when the image density of the image erasing area was measured using a Macbeth densitometer RD914, when the laser beam irradiation position interval (to the irradiation spot diameter ratio) was 1.0 mm (1/3) or more, the image was It was not completely erased.

(Experimental example 2)
In the same manner as in Example 10, a linear image was formed in a range of 10 mm × 50 mm under the condition of a laser beam irradiation spot diameter of 0.18 mm. Next, the laser irradiation condition was fixed at a laser output of 32 W, and the laser beam irradiation spot diameter was appropriately changed within the range of 0.6 to 8.0 mm to erase the image. FIG. 17 shows the relationship between the image erasing time and the laser beam irradiation spot diameter at this time.

  The image processing method and the image processing apparatus of the present invention are capable of repeatedly forming and erasing a high-contrast image at high speed on a thermoreversible recording medium such as a label affixed to a container such as cardboard, in a non-contact manner, In addition, deterioration of the thermoreversible recording medium due to repetition can be suppressed, and the present invention can be used particularly suitably in a physical distribution / distribution system.

FIG. 1A is a schematic explanatory diagram showing an example of the light irradiation intensity of “central part” and “peripheral part” in the light intensity distribution of a cross section orthogonal to the traveling direction of laser light used in the image processing method of the present invention. FIG. 1B is a schematic explanatory diagram illustrating an example of the light irradiation intensity of the “central part” and “peripheral part” in the light intensity distribution of the cross section orthogonal to the traveling direction of the laser light used in the image processing method of the present invention. FIG. 1C is a schematic explanatory diagram illustrating an example of the light irradiation intensity of the “central part” and “peripheral part” in the light intensity distribution of the cross section orthogonal to the traveling direction of the laser light used in the image processing method of the present invention. FIG. 1D is a schematic explanatory diagram showing an example of the light irradiation intensity of “central part” and “peripheral part” in the light intensity distribution of the cross section orthogonal to the traveling direction of the laser light used in the image processing method of the present invention. FIG. 1E is a schematic explanatory diagram showing light irradiation intensities of “central part” and “peripheral part” in the light intensity distribution (Gaussian distribution) of a cross section orthogonal to the traveling direction of normal laser light. FIG. 2A is a schematic diagram for explaining the spot diameter of laser light whose light intensity distribution is a Gaussian distribution. FIG. 2B is a schematic diagram for explaining the spot diameter of laser light used in the image processing method of the present invention. FIG. 3A is a graph showing the transparent-white turbidity characteristics of a thermoreversible recording medium. FIG. 3B is a schematic explanatory diagram showing a mechanism of a change in transparency-white turbidity of a thermoreversible recording medium. FIG. 4A is a graph showing the color-decoloring characteristics of the thermoreversible recording medium. FIG. 4B is a schematic explanatory diagram showing the mechanism of color development-decoloration change of the thermoreversible recording medium. FIG. 5 is a schematic explanatory diagram illustrating an example of an RF-ID tag. FIG. 6A is a schematic explanatory diagram illustrating an example of light irradiation intensity adjusting means in the image processing apparatus of the present invention. FIG. 6B is a schematic explanatory diagram illustrating an example of light irradiation intensity adjusting means in the image processing apparatus of the present invention. FIG. 7 is a schematic explanatory view showing an example of the image processing apparatus of the present invention. FIG. 8 is a schematic explanatory diagram showing a light intensity distribution in a cross section orthogonal to the traveling direction of the laser light used in the image forming process of Example 1. FIG. 9 is a schematic explanatory diagram illustrating the light intensity distribution in a cross section orthogonal to the traveling direction of the laser light used in the image forming process of the second and fifth embodiments. FIG. 10 is a schematic explanatory diagram showing the light intensity distribution in a cross section orthogonal to the traveling direction of the laser light used in the image erasing process of the first embodiment and the image forming process of the third embodiment. FIG. 11 is a schematic explanatory diagram illustrating a light intensity distribution (Gaussian distribution) in a cross section orthogonal to the traveling direction of the laser light used in the image forming process of Comparative Example 1. FIG. 12 is a photograph showing the thermoreversible recording medium after image erasure in Example 10. FIG. 13 is a photograph showing the thermoreversible recording medium after image erasing in Comparative Example 5. FIG. 14 is a photograph showing an intersection portion of intersecting linear images formed in Example 21. FIG. 15 is a photograph showing an intersection portion of intersecting linear images formed in Comparative Example 6. FIG. 16 is a graph showing the relationship between the image erasing time and the laser beam irradiation position interval (vs. spot diameter ratio) in Experimental Example 1. FIG. 17 is a graph showing the relationship between the image erasing time and the laser beam irradiation spot diameter in Experimental Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laser oscillator 12 Beam expander 14 Galvanometer 14A Mirror 15 Scanning unit 81 IC chip 82 Antenna 85 RF-ID tag S Thermoreversible recording medium

Claims (11)

An image forming step of forming an image on the thermoreversible recording medium by irradiating and heating a thermoreversible recording medium in which either transparency or color tone reversibly changes depending on temperature; and Including at least one of an image erasing step of erasing an image formed on the thermoreversible recording medium by irradiating and heating the thermoreversible recording medium with a laser beam;
The image erasing step is to erase the image in the second image erasing area adjacent to the first image erasing area after erasing the image in the first image erasing area by scanning the laser beam. Including
The distance between the laser beam irradiation position on the first image erasing area and the laser beam irradiation position on the second image erasing area is 1/10 to 1/4 of the laser beam irradiation spot diameter. An image processing method characterized by the above. The image processing method according to claim 1, wherein an irradiation spot diameter of the laser beam in the image erasing process is 1 to 33 times larger than an irradiation spot diameter of the laser beam in the image forming process. A thermoreversible recording medium comprising at least a resin and a low-molecular-weight organic substance, and reversibly changing either the transparency or the color tone depending on the temperature. At least one of an image forming process for forming an image on a recording medium and an image erasing process for erasing an image formed on the thermoreversible recording medium by irradiating the thermoreversible recording medium with laser light and heating the recording medium. Including
The image forming step scans the laser beam to form an image in the first image forming area, and then forms an image in a second image forming area adjacent to the first image forming area. Including
After the low molecular weight organic substance located in the first image forming area is melted and before the low molecular weight organic substance is crystallized, the low molecular weight organic substance overlaps a part of the first image forming area. An image processing method comprising irradiating the second image forming area with the laser light.   The organic low molecular weight substance in the thermoreversible recording medium is dispersed in the resin in the form of particles, and the transparency of the thermoreversible recording medium reversibly changes between a transparent state and a cloudy state by heat. Image processing method. The low molecular weight organic substance before melting is a leuco dye and a reversible developer, and after melting, the low molecular weight organic substance before crystallization is the leuco dye and the reversible developer. A coloring mixture of
The image processing method according to claim 3, wherein the color tone of the thermoreversible recording medium is reversibly changed by heat between a transparent state and a colored state.   The image processing according to claim 3, wherein the irradiation of the laser beam onto the first image forming area and the irradiation of the laser beam onto the second image forming area are performed at intervals of 60 seconds or less. Method.   In the laser light irradiated in at least one of the image forming process and the image erasing process, the light irradiation intensity at the central part is the light at the peripheral part in the light intensity distribution in a cross section substantially perpendicular to the traveling direction of the laser light. The image processing method according to claim 1, wherein the image processing method is equal to or less than the irradiation intensity.   8. The light intensity distribution in a cross section in a direction substantially orthogonal to the traveling direction of the laser light in the laser light has a light irradiation intensity at the center portion that is 1.03 times or less of the light irradiation intensity at the peripheral portion. An image processing method described in 1.   The image processing method according to claim 8, wherein in the light intensity distribution in a cross section in a direction substantially orthogonal to the traveling direction of the laser light in the laser light, the light irradiation intensity at the central part is smaller than the light irradiation intensity at the peripheral part. It is used for the image processing method in any one of Claims 7, 8, and 9,
Laser beam emitting means;
An image processing apparatus comprising at least light irradiation intensity adjusting means arranged on a laser light emitting surface of the laser light emitting means and changing the light irradiation intensity of the laser light.   The image processing apparatus according to claim 10, wherein the light irradiation intensity adjusting means is at least one of a lens, a filter, a mask, and a mirror.