JP2000056497A - Erasable image forming material and image forming and erasing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming material on which a sharp image can be produced and a good erased state can be obtd., by incorporating coloring compds., developer, specified matrix agent and decolorizing agent into the image forming material, separating the coloring compds., the developer and the decolorizing agent from the form of microcapsules. SOLUTION: This image forming material contains coloring compds., a developer, a matrix agent having electron donating groups in the total number as <=5% of the total carbon number, and a decolorizing agent. The coloring compds., the developer and the decolorizing agent are separated from the form of microcapsules. The coloring compds. are precursors of dyes which form colored information such as characters and figures, and the developer is a compd. which allows the coloring compd. to produce colors by the interaction with the coloring compd. The decolorizing agent is a compd. having prior solubility with regard to the developer, and is classified into a reversible decolorizing agent, a compatible decolorizing agent and a phase separation inhibitor corresponding to the stability of the decolorized state of the image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming material which is used for electrophotography of a printer, a copying machine, a facsimile or the like, or for thermal transfer recording, and which can be erased after forming an image.

[0002]

2. Description of the Related Art In recent years, as office automation has progressed, the amount of various types of information has increased remarkably, and the output of information has increased accordingly. The output of information is represented by a display output and a hard copy output to paper by a printer. Display output requires a large-scale circuit board in the display unit, and therefore has a problem in terms of portability and cost. On the other hand, the hard copy output is the most basic information display means and has excellent versatility and storability. However, in the case of hard copy output, as information increases, a large amount of paper is used as a recording medium, which leads to an increase in the cutting of wood used as a raw material for paper. Forest resources are very important in terms of maintaining the global environment and controlling the greenhouse effect of carbon dioxide. For this reason, it has become a major issue to minimize the cutting of new timber and to make efficient use of the existing paper resources.

Conventionally, the reuse (recycling) of paper resources is
It is carried out by treating paper on which an image forming material is printed with a large amount of bleach and water, and remaking the paper fibers to produce recycled paper of poor paper quality. Such a method not only increases the cost of recycled paper, but also causes new environmental pollution associated with the treatment of waste liquid.

Further, in the past, paper was reused by correcting images using a poppy rubber for a pencil and a correction liquid for a writing instrument. However, these methods are inefficient for modification and have limited reuse. Recently, rewritable papers and the like for the purpose of reusing hard copy papers have been proposed. However, rewritable paper can be applied only to thermal recording, and it is a special paper that can be reused but cannot be recycled.

On the other hand, the present inventors have proposed a method for forming an image in the same manner as a normal image forming material, which contains a color former, a color developer and a decolorant compatible with these compounds. The development of an image forming material capable of erasing an image by processing with heat or a solvent is being promoted.
When such an erasable image forming material is used, the paper whose image has been erased and returned to a blank state can be reused (reused) many times while minimizing deterioration of the paper quality. Since the paper may be recycled when the quality of the paper due to reuse becomes remarkable, the utilization efficiency of the paper resources is dramatically improved. In this manner, substantial paper usage can be reduced, and logging of timber can be minimized. In addition, the high cost of recycled paper and the environmental pollution caused by waste liquid treatment, which are problems in the current recycling system, can be avoided as much as possible.

The image forming material containing a color former, a color developer, a decoloring agent, a binder resin and the like, which is being developed by the present inventors, is the same as an ordinary electrophotographic toner. Has been found to be able to be formed, and can be erased by a solvent or heating, but the image may remain unerased. Since the unremoved image is a factor that restricts the reuse of paper, there is room for improvement so that the formed image can be erased as completely as possible.

Further, depending on the use of the image forming material, it is sometimes preferable that not only complete erasing but also repetitive writing and erasing of an image can be performed. Therefore, there is also a demand for an image forming material that can be used for such purposes.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming material which can form a clear image and which can obtain a good erased state by heat or solvent treatment.

Another object of the present invention is to provide an image forming material capable of writing and erasing an image in addition to complete erasure.

[0010]

A first erasable image forming material according to the present invention comprises a color former, a developer, and a matrix agent having a total number of carbon atoms of 5% or less of the total number of carbon atoms. When,
A decoloring agent, and the color former and the developer;
The decoloring agent is separated from the decoloring agent by microcapsules.

The second erasable image forming material of the present invention comprises a color former, a color developer, a matrix agent having a total number of electron-donating groups of 5% or less of the total number of carbon atoms, And glass transition point or softening point 2
A polymer filler higher than 0 ° C. or higher, wherein the color former and the developer and the polymer filler are phase-separated or co-dispersed.

A third erasable image forming material of the present invention is a core comprising a color former, a color developer, and a matrix agent having a total number of electron-donating groups of 5% or less of the total number of carbon atoms. In contrast, a polymer filler is externally added, and at least one of the core and the polymer filler contains a decoloring agent.

The first to third image forming materials are used for forming an image formed of a colored image forming material on paper (image recording medium), completely erasing the image and reusing the paper. Is done.

The fourth erasable image forming material of the present invention comprises a color former, a color developer, a decolorizer, a matrix agent having a total number of electron-donating groups of 5% or less of the total number of carbon atoms, and It is characterized by containing an organic solvent having a boiling point of 150 ° C. or higher.

[0015] A fifth erasable image forming material of the present invention comprises a microcapsule containing a color former, a color developer, and an organic solvent having an electron donating group;
And a matrix agent in which the total number of electron donating groups is 5% or less of the total number of carbon atoms.

The sixth erasable image-forming material of the present invention comprises a microcapsule containing a color-forming compound, a microcapsule containing a color developer, and an electron-donating group having a total number of carbon atoms of 5 to 5 carbon atoms. % Or less of a matrix agent and a decoloring agent.

The seventh erasable image-forming material of the present invention comprises a color former, a developer, a reversible decolorant, a compatible decolorant or a phase separation inhibitor, an electron donor, And a matrix agent having a total number of groups of 5% or less of the total number of carbon atoms.

The fourth to seventh image forming materials are used for applications that use reversible coloring and decoloring of the image forming material on paper (image recording medium). After the image is finally erased, the paper can be reused.

According to the image recording / erasing method of the present invention, a colorless image is formed on an image recording medium by using the fourth, fifth or sixth image forming material, and the first heating condition or the first heating condition is applied. The image forming material is colored by the pressure condition or the contact with the first solvent, and the second heating condition, the second pressing condition or the second
Wherein the image forming material is decolorized by contact with the solvent.

According to the image recording / erasing method of the present invention, a colored image is formed on an image recording medium using a seventh image forming material, and the first heating condition or the first pressing condition or the first
The image forming material is decolored by the contact of the solvent, the color is formed by the second heating condition or the second pressurizing condition or the contact of the second solvent, and the third heating condition or the third heating condition is performed. It is characterized in that the image forming material is decolored by pressure conditions or by contact with a third solvent.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The erasable image forming material according to the present invention comprises:
By combining a color former, a developer, and a decolorant,
This enables erasure after image formation. The basic operation of these components will be schematically described. The color-forming compound is a precursor compound of a dye that forms coloring information such as characters and figures, and the color developer is a compound that colors the color-forming compound by interaction with the color-forming compound. Further, the decoloring agent is a compound having a property of being preferentially compatible with the color developing agent at the time of melting or in the presence of a solvent. Until now, low molecular weight compounds have been used as decolorizing agents, and as described below, in accordance with the stability of the decoloring state of an image, a reversible decoloring agent, a compatible decoloring agent, and a phase separation suppressing agent are used. Classified into agents.

These three components, when solidified, can take the following two states. That is, (1) the decolorizing agent is mixed with the color developing compound and the color developing agent in an amount corresponding to the equilibrium solubility, and an excess of the color developing compound and the color developing agent exceeding the equilibrium solubility in the decoloring agent is obtained. A state in which the color developing compound and the color developing agent form a color by interaction with the decoloring agent, and (2) the decolorizing agent takes in the developing agent in a large amount exceeding the equilibrium solubility, and This is a state where the interaction between the compound and the developer is reduced and the color is erased.

The state change between the colored state and the decolored state is performed according to the following principle. At room temperature, the state in which the phase of the color former and the phase of the developer and the phase of the decolorant are phase-separated is close to the equilibrium state. In this case, the color-forming compound and the color developer interact to form a colored state. From this state, when the composition system is heated to a temperature equal to or higher than the melting point, the color developer is preferentially dissolved in the decolorizing agent in the fluid state, and loses the interaction with the color forming compound, so that the color is changed to the decolored state. When the composition in the molten state is cooled and solidified, the decolorizing agent takes in a developer in an amount exceeding the equilibrium solubility to become amorphous and becomes colorless at room temperature. The amorphous composition system is in a relatively non-equilibrium state, but has a sufficiently long life at a temperature lower than the glass transition point Tg, and easily equilibrates from the amorphous state when Tg is higher than room temperature. It does not move to the state.

When a solvent is applied to an image-forming material containing three components of a color-forming compound, a color developer and a decolorant, the color is changed from the color-developed state to the decolored state according to the same principle as described above. Can be changed. An image can also be erased by allowing a solvent containing a decoloring agent to act on an image forming material containing a color former and a developer.

The image forming material of the present invention can be used in various forms. For example, electrophotographic toners (developers) such as copiers (PPCs), laser printers, and faxes; inks for thermal printers; inks for inkjet printers; printing inks for screen printing and printing; writing utensils such as ballpoint pens and fountain pens Can be used as an ink. Using the image forming material of the present invention, an image can be formed on various image recording media. Typical examples of the sheet-shaped image recording medium include paper and a polymer film. The image recording medium also includes a container, a package, a structure, and the like to which a sheet-like image forming material is adhered.

First, the first to third image forming materials of the present invention will be described.

The present inventors have found that when the image forming material is erased with a solvent, traces of the flow of the image forming material and blurring of the image are caused by uneven dispersion of the decoloring agent. I found it. It is considered that this is because the decoloring agent has a strong cohesive force and easily forms aggregates in the image forming material.

The matrix agent used in the present invention means a so-called binder resin or wax component, and a compound having a total number of electron-donating groups of 5% or less of the total number of carbon atoms (an oligomer or a polymer in the case of a resin). Consists of

The polymer filler used in the present invention is present in the form of a coating material, an external additive, dispersed particles, or a binder for dispersing microcapsules in the image forming material. It is a polymer compound having a function of retaining the structure. Polymer fillers
It is preferred that the oligomer or polymer has a total number of electron donating groups exceeding 5% of the total carbon number.

The first image forming material has a structure in which a color former, a color developer, and a decolorant are separated by microcapsules. Microcapsules are destroyed by external stimuli such as light, heat, and contact with solvents. The material encapsulated as the core of the microcapsule may be a pigment component (a color former and a color developer) or a decolorant. Further, the pigment component may be microencapsulated and covered with a polymer filler. This is because it is advantageous for improving the dispersion state, and the production variation of the image forming material is reduced.

The second image forming material has a structure in which a color former and a developer and a polymer filler are phase-separated or co-dispersed. In this case, the polymer filler needs to have a Tg or softening point higher than the matrix agent by 20 ° C. or more (preferably 50 ° C. or more). Further, the image forming material is kneaded under a condition lower than the Tg or the softening point of the polymer filler.

The third image forming material was externally added to a core containing a color former, a color developer, and a matrix agent by attaching a polymer filler as a powder to the outer periphery of the core. Having a structure.

The specific structure of the first to third image forming materials of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. In these figures, L indicates a color-forming compound, D indicates a color developer, EA indicates a decoloring agent, P indicates a polymer filler, and BP indicates a matrix agent (binder resin or wax component). However, the phase-separated structure or co-dispersed structure of the second image-forming material does not necessarily have to have a structure in which each component is clearly separated as shown in these figures.

The toner particles (A) have a structure in which a core containing a coloring compound, a developer and a matrix agent is covered with a polymer filler. The toner particles (B) have a structure in which a microcapsule composed of a core containing a coloring compound, a color developer and a matrix agent and a shell surrounding the core is covered with a polymer filler. The toner particles (C) have a structure in which a core including a color former, a color developer, a matrix agent, and a decolorant is covered with a polymer filler. In other words, it has a structure in which the decoloring agent is dispersed in the core of (A). The toner particles (D) have a structure in which a microcapsule composed of a core containing a color former, a color developer, a matrix agent, and a decoloring agent and a shell surrounding the core is covered with a polymer filler. In other words, it has a structure in which the decoloring agent is dispersed in the core of (B). In any case, the decoloring agent may be dispersed in the outermost polymer filler covering the core or the microcapsule ((A ′),
(B '), (C'), (D ')). In the structure of (A) or (B), the core may contain not only a matrix agent but also a polymer filler.

The toner particles (E) are formed by adhering a polymer filler powder around a core (similar to the core of (A)) containing a color former, a developer and a matrix agent. It has an attached structure. The toner particles of (F) are obtained by adhering a polymer filler powder around a core (similar to the core of (C)) containing a color former, a developer, a matrix agent and a decolorant. Has an externally added structure. In either case,
A decoloring agent may be dispersed in the powder of the polymer filler externally added ((E ′), (F ′)). In (E), the matrix agent can be omitted.

The toner particles (G) have a structure in which a core containing a coloring compound, a color developer and a matrix agent is prepared, and a plurality of cores are phase-separated in a polymer filler. The toner particles (H) have a structure in which a core containing a coloring compound, a color developer, a matrix agent, and a decoloring agent is prepared, and a plurality of cores are phase-separated in a polymer filler. In other words, it has a structure in which the decoloring agent is dispersed in the core of (G). In the toner particles of (I), both a core composed of a color former, a developer and a matrix agent, and a core composed of a decolorant were respectively prepared, and a plurality of cores were phase-separated in a polymer filler. Having a structure. In either case,
A decoloring agent may be dispersed in a polymer filler ((G ′),
(H ')). In (G) and (I), the matrix agent can be omitted.

The toner particles (J) are prepared by preparing microcapsules comprising a core containing a coloring compound, a color developer and a matrix agent and a shell enclosing the core, and incorporating a plurality of microcapsules in a polymer filler. It has a dispersed structure. The toner particles (K) produce microcapsules comprising a core containing a color former, a developer, a matrix agent and a decolorant, and a shell enclosing the core.
It has a structure in which a plurality of microcapsules are dispersed in a polymer filler. The toner particles of (L) are a coloring compound,
A microcapsule consisting of a core comprising a developer and a matrix agent and a shell enclosing the same, and a microcapsule consisting of a core comprising a decolorant and a shell enclosing the same were each prepared, and a plurality of cores were placed in a polymer filler. It has a structure dispersed in. In other words, (J),
(K) and (L) are structures in which a shell separating the two exists between the cores of (G), (H) and (I) and the polymer filler, respectively. Further, a decoloring agent may be dispersed in the polymer filler ((J ′), (K ′)).

The toner particles (M) have a structure in which a coloring compound, a developer and a matrix agent are uniformly dispersed, and a polymer filler is phase-separated or pigment-dispersed.
The toner particles (M ′) have a structure in which a color former, a developer, a decolorant, and a matrix agent are uniformly dispersed, and a polymer filler is phase-separated or dispersed in a pigment.

Each of the structures (A) to (M) has advantages and disadvantages. For example, toner particles containing a plurality of cores such as (G) to (M) can obtain a better erased state, especially when erased with a solvent, as compared to toner particles having a single core. On the other hand, the manufacturing process becomes complicated. Also, comparing the microcapsule structure in which the core is wrapped in a shell with the phase separation structure in which the core is simply dispersed, the microcapsule structure has excellent image retention and stability, and the phase separation structure has a simple manufacturing process. However, there is a limitation that it is necessary to use a material having a Tg or a softening point higher than that of the binder resin by at least 20 ° C. or more as the polymer filler. Also, as shown in the drawing, when the decoloring agent is contained in the polymer filler exposed on the outermost periphery, a good erasing state can be obtained particularly when erasing with a solvent, but on the other hand, the charging of the toner State stability is slightly inferior.
Therefore, it is preferable to select an appropriate polymer filler and a manufacturing process in consideration of the structure of the toner.

For example, in the simplest structures (A) and (G) containing a coloring compound, a color developer, a matrix agent and a polymer filler, the amount of the electron donating group in the polymer filler is And the compatibility with the erasing solvent. Generally, the lower the amount of the electron donating group in the polymer filler, the higher the reflection density of the image formed by the image forming material. On the other hand, the higher the compatibility of the polymer filler with the erasing solvent, the lower the reflection density of the paper after solvent erasure.

The specific structure of the first to third image forming materials of the present invention will be described with reference to FIGS. 5 and 6A to 6F using a thermal transfer ink ribbon as an example. The symbols used in these figures are the same as in FIGS.
As shown in (A) to (F), the thermal transfer ink ribbon is
The back coat film 12 is formed on the back surface of the base film 11, and the ink film 13 is applied to the front surface of the base film 11. The appropriate ink film thickness is determined in consideration of the image density and the thermal transfer characteristics.
m, more preferably in the range of 2 to 8 μm.

The ink film (A) has a structure in which a core containing a coloring compound, a color developer and a matrix agent is dispersed in a polymer filler. The ink film of (B) has a structure in which a core containing a color former, a developer, and a decolorant is dispersed in a polymer filler. The ink film of (C) has a structure in which a microcapsule composed of a core containing a coloring compound, a color developer and a matrix agent (binder resin) and a shell surrounding the core is dispersed in a polymer filler. The ink film of (D) has a structure in which a microcapsule consisting of a core containing a color former, a developer and a decolorant, and a shell surrounding the core is dispersed in a polymer filler. The ink film of (E) includes both a microcapsule comprising a core comprising a color former, a color developer and a matrix agent and a shell enclosing the core, and a microcapsule comprising a core comprising a decolorant and a shell enclosing the core. And a structure in which these cores are dispersed in a polymer filler. The ink film of (F) has a phase separation structure in which a color former, a developer, and a matrix agent are uniformly dispersed, and a polymer filler having a Tg higher than the matrix agent by 20 ° C. or more is dispersed in a pigment. Having.

The case where the first to third image forming materials of the present invention are applied to liquid ink will be described. In the case where the pigment component is added in the liquid ink by being microencapsulated in a shell that is not affected by the ink solvent (for example, a gelatin shell for a water-insoluble organic solvent), there is little restriction on the material of the polymer filler. On the other hand, when the pigment component is dispersed in a solvent-insoluble binder in the liquid ink and added without a shell, it is more advantageous to use a low-polarity organic solvent as the ink solvent in order to prevent a decrease in image density. is there. In this case, it is preferable to use a polymer filler that dissolves in a low-polarity solvent.

Next, the fourth to seventh image forming materials of the present invention will be described.

The fourth to sixth image forming materials form a colorless image on paper, develop a color under the first heating condition or the first pressurizing condition or contact with the first solvent, and perform the second heating It is used under a condition or a second pressurizing condition or a method of decoloring by contact with a second solvent. The paper which is finally in a stable or metastable decolored state can be reused.

The seventh image forming material forms a color-developed image on paper, erases the color by the first heating condition, the first pressing condition, or the contact with the first solvent, and the second heating condition or the second heating condition. The color is developed by the second pressurizing condition or the contact with the second solvent, and the third heating condition, the third pressurizing condition or the third
Used in the method of decoloring by contact with a solvent. The paper which is finally in a stable or metastable decolored state can be reused.

If these image forming materials are used, for example, only the confidential information is recorded in a decolored state, and the confidential information is colored later, whereby the security of the information can be maintained.

The image forming materials according to the fourth to seventh aspects of the present invention will be described using liquid ink as an example.

The fourth erasable image forming material of the present invention comprises a color former, a color developer, a decolorizer, a matrix agent having a total number of electron-donating groups of 5% or less of the total carbon number, and Contains an organic solvent having a boiling point of 150 ° C. or higher. The organic solvent used in the fourth invention has a boiling point of 150 ° C. or higher,
Further, the temperature is preferably 180 ° C. or higher. This organic solvent preferably has one or less electron donating groups.
Specific examples of the electron donating group included in the organic solvent include a hydroxyl group, an ether group, an acyl group, a carboxyl group, and an ester group. The matrix agent used in the fourth invention includes a non-polar wax or a resin (polymer or oligomer) which is non-polar or has a low content of a polar group.

This image forming material is transferred onto paper by, for example, ink jet recording, and the ink solvent is vaporized.
At this point, since the organic solvent having a high boiling point and being difficult to vaporize (delay vaporization) remains in the image forming material, the interaction between the color former and the developer is inhibited, and the image forming material is colorless (latent image formation). ). The time during which this state can be maintained is determined by the vaporization rate of the high-boiling organic solvent, but has a sufficiently long life at room temperature. Next, under the first condition, the high-boiling organic solvent is removed by heating, or by contacting the high-boiling organic solvent with a solvent capable of removing the high-boiling organic solvent, the image forming material is colored in a short time so that it can be visually recognized. (Development). Further, under the second condition, when heated or brought into contact with an erasing solvent, the decoloring agent becomes compatible with the color developing agent, so that the image forming material is decolorized and becomes invisible (erasing). Since the image forming material after erasure does not develop color again under the developing condition, the paper can be reused.
When developing and erasing are performed by heating, the second heating condition is generally higher in temperature than the first heating condition.

The fourth image forming material can be manufactured by a simple process. However, the initial decolored state is maintained by the fact that the high-boiling organic solvent is not vaporized, so that it is easily affected by temperature and has low stability. For this reason, it is preferable that the fourth image forming material is applied only to a liquid ink (for example, a writing instrument or ink jet recording) capable of forming a latent image by a non-heating process.

The fifth erasable image forming material of the present invention comprises: a microcapsule containing a color former, a color developer, and an organic solvent having an electron donating group;
A matrix agent in which the total number of electron donating groups is 5% or less of the total number of carbon atoms. The organic solvent used in the fifth invention only has to have at least one electron donating group, and preferably has a high vaporization rate, contrary to the organic solvent used in the fourth invention. As the matrix agent used in the fifth invention, similarly to the fourth invention, a non-polar wax or a resin (polymer or oligomer) which is non-polar or has a low polar group content is exemplified. In the fifth invention, a polar wax or a polar resin (polymer or oligomer) having a small acid value can be suitably used from the viewpoint of the erased state and the adhesion strength of the image forming material.

At the time when the image forming material is formed on paper, the organic solvent remains in the microcapsules in the image forming material, so that the interaction between the color former and the developer is inhibited, and the image forming material is colorless. (Latent image formation). Next, under the first condition, when heating, pressurizing, or contacting a solvent that can break the microcapsules, the microcapsules are broken, the polar organic solvent is rapidly vaporized, and the image forming material develops color in a short time. To make the image visible (development). Further, under the second condition, when heated or brought into contact with an erasing solvent, the decoloring agent becomes compatible with the color developing agent, so that the image forming material is decolorized and cannot be visually recognized (erased), and the paper can be reused.

The sixth erasable image-forming material of the present invention comprises a microcapsule containing a color-forming compound, a microcapsule containing a color developer, and an electron-donating group having a total number of carbon atoms of 5 or less. % Or less of a matrix agent and a decoloring agent.

When the image forming material is formed on paper, the image forming material is colorless because the microencapsulated color developing compound and the developer are separated in the image forming material (latent image formation). Next, under the first condition, heating, pressurizing, or contact with a solvent that can break the microcapsules, the microcapsules are broken, and the developer and the color developing compound contained therein interact, The image forming material develops color and the image can be visually recognized (development). Further, under the second condition,
When heated or brought into contact with an erasing solvent, the decoloring agent becomes compatible with the color developing agent, so that the image forming material is decolorized and becomes invisible (erasing), and the paper can be reused.

The seventh erasable image forming material of the present invention comprises a color former, a developer, a reversible decolorant, a compatible decolorant or a phase separation inhibitor, an electron donor A matrix agent having a total number of groups of 5% or less of the total number of carbon atoms. The reversible color erasing agent used in the seventh invention greatly differs in compatibility with a color developing material depending on its crystallinity (crystalline or amorphous), and controls image formation by controlling the crystallinity. It is a material that can reversibly change the coloring and decoloring of the material. On the other hand, a compatible decolorizer has a high affinity with a color developer at the time of melting and has very high compatibility, and also has a high amorphous property, so that phase separation hardly occurs even after the composition system is solidified. Material. Similarly, a phase separation inhibitor is a material that hardly undergoes phase separation after solidification. In this sense, a compatible color erasing agent or phase separation inhibitor can be said to be an irreversible color erasing agent. In the seventh invention, it is preferable that the compatible decoloring agent or the phase separation inhibitor is dispersed in a phase separation structure or a microcapsule structure.

At the time when the image forming material is formed on paper, the color forming compound and the developer interact in the image forming material to form a color (transfer). Next, under the first condition,
When heated to a temperature exceeding the melting point of the reversible decoloring agent, the reversible decoloring agent becomes compatible with the developer and is taken in, resulting in a colorless state (latent image formation). Next, when the latent image is heated under the second condition, the latent image re-colors and becomes visible (development). further,
Under the third condition, the image forming material is decolorized by heating, pressing or contacting with a solvent that can break the microcapsules, so that the compatible decoloring agent or phase separation inhibitor is compatible with the developer. And cannot be visually recognized (erase), and the paper can be reused.

The specific structure of the fourth to seventh image forming materials of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. In these figures, L is a coloring compound, D is a developer, S is a polar organic solvent, EA is a decolorant (compatible decolorant or phase separation inhibitor), RE is a reversible decolorant, P indicates a polymer filler, and BP indicates a matrix agent (binder resin or wax component).

The toner particles (A) have a structure in which a microcapsule composed of a core containing a color former, a developer and a polar organic solvent and a shell enclosing the core is covered with a polymer filler. (A ′) has the same structure as (A), except that a decoloring agent is dispersed in a polymer filler covering the microcapsules.

The toner particles (B) have a structure in which a microcapsule consisting of a core containing a color former, a developer and a reversible decolorant and a shell enclosing the core is covered with a polymer filler. (B ′) has a structure similar to that of (B), except that a decoloring agent is dispersed in a polymer filler covering the microcapsule core.

The toner particles of (C) are microcapsules composed of a core containing a color former, a color developer and a polar organic solvent and a shell enclosing the core (similar to the core of (A)).
And a structure in which a polymer filler powder is adhered and externally added. (C ′) has a structure similar to that of (C), except that a decoloring agent is dispersed in a polymer filler externally added around the microcapsule core.

The toner particles (D) are microcapsules comprising a core containing a color former, a color developer and a reversible decolorant, and a shell enclosing the core (similar to the core of (B)).
And a structure in which a polymer filler powder is adhered and externally added. (D ′) has the same structure as (D), but a decolorant is dispersed in a polymer filler externally added around the microcapsule core.

For the toner particles (E), microcapsules composed of a core containing a color former, a color developer and a polar organic solvent and a shell enclosing the core are prepared. Having a phase-separated structure. (E ′) has the same structure as (E), but the decolorant is dispersed in the polymer filler around the microcapsule core.

For the toner particles (F), a microcapsule comprising a core containing a color former, a color developer and a reversible decolorant and a shell surrounding the core is prepared, and a plurality of microcapsules are filled with a polymer. It has a structure in which the phase is separated in the agent. (F ′) has the same structure as (F), but the decolorant is dispersed in the polymer filler around the microcapsule core.

The toner particles (G) include a microcapsule composed of a core made of a color-forming compound and a shell enclosing the same, a microcapsule composed of a core composed of a developer and a shell enclosing the same, and a core composed of a decolorant. And a microcapsule composed of a shell enclosing the microcapsule and a plurality of cores dispersed in a polymer filler.

For the toner particles (H), a microcapsule consisting of a core made of a decoloring agent and a shell enclosing the core is prepared, and a plurality of cores are made up of a coloring compound, a developer and a reversible decoloring agent in a matrix. It has a structure dispersed in an agent.

Also when the fourth to seventh image forming materials of the present invention are applied to a thermal transfer ink ribbon, the surface of the substrate film is not shown in FIGS. 7 to 9A to 9H. What is necessary is just to apply an ink film so that it may become the same structure.

Hereinafter, the components constituting the image forming material of the present invention will be described more specifically.

Examples of the color-forming compound used in the present invention include electron-donating compounds such as leuco auramine, diaryl phthalide, polyaryl carbinol, acyl auramine, aryl auramine, rhodamine B lactam, indoline, spiropyran, and fluoran. Organic substances.

Specific color-forming compounds include crystal violet lactone (CVL), malachite green lactone, 2-anilino-6- (N-cyclohexyl-
N-methylamino) -3-methylfluoran, 2-anilino-3-methyl-6- (N-methyl-N-propylamino) fluoran, 3- [4- (4-phenylaminophenyl) aminophenyl] amino -6-methyl-7-chlorofluoran, 2-anilino-6- (N-methyl-N
-Isobutylamino) -3-methylfluoran, 2-anilino-6- (dibutylamino) -3-methylfluoran, 3-chloro-6- (cyclohexylamino) fluoran, 2-chloro-6- (diethylamino) fluoran , 7- (N, N-dibenzylamino) -3- (N, N
-Diethylamino) fluoran, 3,6-bis (diethylamino) fluoran-γ- (4′-nitroanilino)
Lactam, 3-diethylaminobenzo [a] -fluoran, 3-diethylamino-6-methyl-7-aminofluoran, 3-diethylamino-7-xylidinofluoran, 3- (4-diethylamino-2-ethoxyphenyl)- 3- (1-ethyl-2-methylindole-3-
Yl) -4-azaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, 3-diethylamino-7-chloroanilinofluoran, 3-diethylamino- 7,8-
Benzofluorane, 3,3-bis (1-n-butyl-2
-Methylindol-3-yl) phthalide, 3,6-dimethylethoxyfluoran, 3,6-diethylamino-
6-methoxy-7-aminofluoran, DEPM, AT
P, ETAC, 2- (2-chloroanilino) -6-dibutylaminofluoran, crystal violet carbinol, malachite green carbinol, N- (2,
3-dichlorophenyl) leuco auramine, N-benzoyl auramine, rhodamine B lactam, N-acetyl auramine, N-phenyl auramine, 2- (phenyliminoethanedylidene) -3,3-dimethylindoline, N, 3 , 3-Trimethylindolinobenzospiropyran, 8'-methoxy-N, 3,3-trimethylindolinobenzospiropyran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-7
-Methoxyfluoran, 3-diethylamino-6-benzyloxyfluoran, 1,2-benzo-6-diethylaminofluoran, 3,6-di-p-toluidino-4,
5-dimethylfluoran, phenylhydrazide-γ-lactam, 3-amino-5-methylfluoran and the like. These can be used alone or in combination of two or more. By appropriately selecting a color-forming compound, a variety of colors can be obtained, so that it is possible to cope with multi-colors.

The developer used in the present invention includes phenol, phenol metal salt, carboxylic acid, carboxylic acid metal salt, benzophenone, sulfonic acid, sulfonic acid salt, phosphoric acid, metal phosphate, acid phosphate, Examples include acidic compounds such as acid phosphate metal salts, phosphorous acid, and metal phosphite salts. These can be used alone or in combination of two or more.

More preferred color developing agents include gallic acid; gallic acid esters such as methyl gallate, ethyl gallate, n-propyl gallate, i-propyl gallate and butyl gallate; 2,3-dihydroxybenzoic acid Acid, 3,5
Dihydroxybenzoic acid such as methyl dihydroxybenzoate and its ester; 2,4-dihydroxyacetophenone, 2,5-dihydroxyacetophenone, 2,
Acetophenone derivatives such as 6-dihydroxyacetophenone, 3,5-dihydroxyacetophenone, 2,3,4-trihydroxyacetophenone; 2,4-dihydroxybenzophenone, 4,4′-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone , 2,4,4'-trihydroxybenzophenone,
Benzophenone derivatives such as 2,2 ', 4,4'-tetrahydroxybenzophenone and 2,3,4,4'-tetrahydroxybenzophenone; biphenols such as 2,4'-biphenol and 4,4'-biphenol;
[(4-hydroxyphenyl) methyl] -1,2,3-
Benzenetriol, 4-[(3,5-dimethyl-4-
Hydroxyphenyl) methyl] -1,2,3-benzenetriol, 4,6-bis [(3,5-dimethyl-4-
Hydroxyphenyl) methyl] -1,2,3-benzenetriol, 4,4 ′-[1,4-phenylenebis (1
-Methylethylidene) bis (benzene-1,2,3-triol)], 4,4 '-[1,4-phenylenebis (1-methylethylidene) bis (1,2-benzenediol)], 4,4 And polyhydric phenols such as ', 4 "-ethylidenetrisphenol, 4,4'-(1-methylethylidene) bisphenol, and methylenetris-p-cresol.

When an image is formed on paper (image recording medium) containing cellulose as a main component, a carboxylic acid developer, a phenolic developer having a carboxyl group, and a phenolic developer having a sugar skeleton (spirostan structure) are used. It is preferable to use a developer or the like. Examples of the carboxylic developer include succinic acid, tartaric acid, malic acid, racemic malic acid, maleic acid, fumaric acid, citric acid, aconitic acid, and itaconic acid. Examples of the phenolic developer having a carboxyl group include 1-hydroxybenzoic acid, 2-hydroxybenzoic acid, 2,3-dihydroxybenzoic acid, and gallic acid. Examples of the phenolic developer having a sugar skeleton include esters of a phenolic developer having a carboxyl group and a saccharide (D-glucose, D-mannose, D-galactose, D-fructose, etc.), for example, gallic acid-D -Glucose monoester and the like. The developer having a carboxyl group interacts with a hydroxyl group of cellulose constituting paper in the form of a hydrogen bond or an ester bond, and is confined in the paper fiber. The phenolic developer having a sugar skeleton is trapped in paper fibers by adhesion or adsorption due to structural similarity with the cellulose skeleton.

The color erasing agent used in the present invention is a material which exhibits compatibility with the color developing agent and makes it difficult to remove the color developing agent taken in due to interaction such as steric hindrance or hydrogen bonding. It is desirable that the decoloring agent has good colorlessness when in the amorphous state. The more the decoloring agent is amorphous and colorless and transparent, the more the paper can be returned to a state close to the original white paper when the image forming material is decolorized. Since such properties are required, the decoloring agent is preferably a compound having a large molecular weight, a small change in enthalpy of melting ΔH per crystal and a small maximum crystal growth rate MCV. If the change in enthalpy of melting ΔH of the crystal of the decoloring agent is small, the amount of heat energy required for melting the crystal becomes small, which is also preferable in terms of energy saving. In order to increase the solubility of the color developer in the color erasing agent, for example, a compound having an alcoholic hydroxyl group is suitable. From the viewpoint of storage stability of the composition system in the decolored state, the glass transition point Tg of the composition system needs to be at least room temperature (25 ° C.), and more preferably 50 ° C. or higher.
In order to satisfy this condition, the glass transition point of the decoloring agent is preferably at least room temperature (25 ° C.), more preferably at least 50 ° C. On the other hand, the crystallization temperature of the decoloring agent is in a temperature range between the glass transition point Tg and the melting point Tm of the composition system. Therefore, in order to speed up the erasing, the glass transition point of the decoloring agent is preferably 150 ° C. or lower. Preferred decoloring agents satisfying these conditions include the following compounds (a) to (c).

(A) Sterol compound. Specific examples of the sterol compound include cholesterol, stigmasterol, pregnenolone, methylandrostenediol, estradiol benzoate, epiandrostene, stenolone, β-sitosterol, pregnenolone acetate, β-cholesterol, and 5,16-pregnadien-3β -All-20-one, 5α-pregnene-3β-ol-20-one, 5-pregnene-3
β, 17-diol-20-one 21-acetate,
5-pregnene-3β, 17-diol-20-one
17-acetate, 5-pregnene-3β, 21-diol-20-one 21-acetate, 5-pregnene-3β, 17-diol diacetate, locogenin,
Tigogenin, esmilagenin, hecogenin, diosgenin and derivatives thereof. These decoloring agents can be used alone or in combination of two or more.
A material that is originally a mixture, such as lanolin alcohol, may be used.

In the case where the decolorizing agent (a) is used, when the composition in the amorphous state is heated to a temperature exceeding the glass transition point, the diffusion speed of the developer rapidly increases, and the direction of returning to the equilibrium state is obtained. Then, the phase separation movement between the color developer and the decolorant is accelerated. Then, when the composition system is heated to a temperature equal to or higher than the crystallization temperature and lower than the melting point, and then gradually cooled to room temperature, a more stable phase separation state close to an equilibrium state is returned to the color development state. The composition system using the decoloring agent of (a) can, in principle, reversibly repeat a colored state and a decolored state. In this sense, the color erasing agent (a) is referred to as a “reversible color erasing agent”.

(B) Cholic acid, lithocholic acid, testosterone and cortisone, and derivatives thereof. Specific examples include cholic acid, cholic acid methyl ester, sodium cholate, lithocholic acid, lithocholic acid methyl ester, sodium lithocholic acid, hyodeoxycholic acid, hyodeoxycholic acid methyl ester, testosterone, methyltestosterone, 11α-hydroxymethyl Testosterone, hydrocortisone, cholesterol methyl carbonate, α-cholestanol. Among them, those having two or more hydroxyl groups are particularly preferable.

The color erasing agent (b) has a higher affinity with the color developer at the time of melting than the color erasing agent (a), and has very high compatibility. In addition, since the decoloring agent (b) has a high amorphous property, phase separation hardly occurs even after the composition system is solidified. In this sense, the color erasing agent (b) is referred to as a "compatible color erasing agent". (B)
In the composition system using the decolorizing agent, a more stable decolored state can be obtained.

(C) 5-membered or more non-aromatic cyclic compounds having one or more hydroxyl groups. The melting point of these compounds is preferably 50 ° C. or higher. Specific examples include alicyclic monohydric alcohols (eg, cyclododecanol), alicyclic dihydric alcohols (eg, 1,4-cyclohexanediol, 1,2-cyclohexanediol, 1,2-cyclododecanediol), saccharides And its derivatives (eg, glucose, saccharose), and alcohols having a cyclic structure (eg, 1,2,5,6)
-Diisopropylidene-D-mannitol).

The decoloring agent (c) may be used alone,
It is particularly effective when used together with the decoloring agent (a). That is, the decoloring agent of (c) has a strong affinity with the decoloring agent of (a), and hardly causes phase separation even after being solidified. In this sense, the decolorizing agent of (c) is referred to as “phase separation suppressing decoloring agent” or “phase separation suppressing agent”. Even when the decoloring agent of (c) is used, a more stable decolored state can be obtained.

The decolorizing agent (c), that is, the phase separation inhibitor described above, can be further classified into two types. That is, (c1) a compound having a relatively high melting point and a glass transition point and easily becoming amorphous at ordinary temperature (highly amorphous phase separation inhibitor)
And (c2) a compound which has a relatively low melting point and glass transition point and is unlikely to become amorphous at normal temperature and may form microcrystals, but has a very high compatibility with a color developer in a fluid state ( A low-amorphous phase separation inhibitor). If both a highly amorphous phase separation inhibitor and a low amorphous phase separation inhibitor are used as the decoloring agent, a very good decolored state can be obtained.

A preferred highly amorphous phase separation inhibitor is a cyclic sugar alcohol. Specific examples include D-glucose,
D-mannose, D-galactose, D-fructose, L-sorbose, L-rhamnose, L-fucose,
D-ribodesource, α-D-glucose = pentaacetate, acetoglucose, diacetone-D-glucose, D-glucuronic acid, D-galacturonic acid, D-glucosamine, D-fructosamine, D-isosugaric acid, vitamin C, eltorbin Acid, trehalose, saccharose,
Maltose, cellobiose, gentiobiose, lactose, melibiose, raffinose, gentianose,
Melezitose, stachyose, methyl = α-glucopyranoside, salicin, amygdalin, euxanthinic acid. One or more of these can be used.

Suitable low-amorphous phase separation inhibitors are non-aromatic cyclic compounds having a hydroxyl group other than a cyclic sugar alcohol and having 5 or more membered rings or derivatives of cyclic sugar alcohols. Is terpene alcohol. Specific examples include alicyclic monohydric alcohols such as cyclododeanol, hexahydrosalicylic acid, menthol, isomenthol, neomenthol, neoisomenthol, carbomenthol, α-carbomenthol, piperitol, α-terpineol, β-terpineol. Γ-terpineol, 1-p-menten-4-ol, isopulegol, dihydrocarbeol, carveol; alicyclic polyhydric alcohols such as 1,4-cyclohexanediol, 1,2-cyclohexanediol, phloroglucitol, Quercitol, inositol, 1,2-cyclododecanediol, quinic acid, 1,4-terpine,
1,8-terpine, pinol hydrate, betulin; polycyclic alcohol derivatives such as borneol, isoborneol, adamantanol, norborneol, fenchol, camphor; derivatives of cyclic sugar alcohols;
For example, 1,2,5,6-diisopropylidene-D-mannitol can be mentioned. One or more of these can be used.

As the decoloring agent, it is preferable to use a compound of biological origin. For example, sterol compounds include animal sterins, plant sterins, fungal sterins and derivatives thereof. Specifically, as animal sterins, cholesterol, lanosterol, lanostadiel, agnosterol, cholestanol, coprostanol, ostreasterol, actinia sterol, spongosterol, crionasterol, etc .; bile acids such as colanic acid, cholic acid Phytosterin such as stegmasterol, α-sitosterol, β-sitosterol, γ-sitosterol, brassicasterol, vitamin D, and the like; and fungal sterin such as ergosterol. In addition, saccharides and their derivatives are widely used for food and have high safety.

In the present invention, as the polymer filler (oligomer or polymer), polyacrylic acid, polymethacrylic acid, polyhydroxyethyl methacrylate, polyacrylamide, polymethacrylamide, polyphenylene, polyether sulfone, polyether ketone, polysulfone , Polyamide, borbenzimidazole, polyphenylene ether, polyphenylene sulfide, polycarbonate, polydivinylbenzene, melanin resin and the like.

In addition, in all cases, the weight ratio of the electron-donating polar monomer is at least 15 wt%,
An acrylate copolymer, a polystyrene / acrylic acid copolymer, a polystyrene / methacrylic acid copolymer, a polystyrene / epoxy-modified styrene copolymer and the like can be mentioned. Here, as the acrylate monomer constituting the polystyrene / acrylate copolymer, n-butyl methacrylate, isobutyl methacrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, diethylaminopropyl Examples include acrylate, 2-ethylhexyl acrylate, butyl acrylate-N- (ethoxymethyl) acrylamide, ethylene glycol methacrylate, and 4-hexafluorobutyl methacrylate.

A polymer filler suitable for using the image forming material of the present invention as a toner will be described. For the polystyrene / acrylate copolymer-based binder resin, the former group of polymer fillers can be suitably used in combination. Any of the above polymer fillers can be suitably used in combination with a polystyrene or polyester resin binder. When the pigment component and the polymer filler are phase-separated, a polymer filler having a Tg or a softening point higher than that of the binder resin by 20 ° C. or more (preferably 50 ° C. or more) is used.

A polymer filler suitable for using the image forming material of the present invention as a liquid ink will be described. When the pigment component is added in the form of microcapsules in the liquid ink, there is little restriction on the material of the polymer filler. In this case, as a polymer filler, polystyrene / acrylate copolymer, polyacrylic acid, polymethacrylic acid, polybiphenyl acrylate, polyacrylamide, polymethacrylamide, polyvinyl ester, polyphenylene, polyether sulfone, polyether ketone, polysulfone , Polyamide, boribendiimidazole, polyphenylene ether, polyphenylene sulfide, polycarbonate, polydivinylbenzene, melanin resin, and the like. Further, a soft polar resin having a relatively low molecular weight and a relatively low glass transition point can be used as the polymer filler. Specifically, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-maleic anhydride copolymer, ethylene-acrylate ester-maleic anhydride copolymer, propylene-vinyl acetate copolymer Propylene / ethyl acrylate copolymer, propylene / maleic anhydride copolymer, propylene / acrylate / maleic anhydride copolymer, butylene / vinyl acetate copolymer, butylene / butyl acrylate copolymer, butylene / anhydride Maleic acid copolymer, butylene / acrylate / maleic anhydride copolymer;

On the other hand, when the dye component is dispersed in a solvent-insoluble binder and added without a shell in the liquid ink, a low-polarity organic solvent should be used as the ink solvent in order to prevent a decrease in image density. Is advantageous. In this case, it is preferable to use a polymer filler that dissolves in a low-polarity solvent, and polyvinyl alcohol and a copolymer thereof are suitable.

A color-forming compound in the image-forming material of the present invention,
Preferred mixing ratios of the color developer and the decoloring agent are as follows. The compounding ratio of the color developer is preferably set to 1 to 10 times, more preferably 1.1 to 5 times, the molar amount of the color former 1. When the amount of the color developer is less than 1 mol, the color development of the image forming material due to the interaction between the color former and the color developer becomes insufficient. When the amount of the developer exceeds 10 times the molar amount, it is difficult to sufficiently reduce the interaction between the two. The mixing ratio of the decoloring agent is 1 to 1 part by weight of the coloring compound.
It is preferable to set to 200 parts by weight, more preferably 5 to 100 parts by weight. When the amount of the decoloring agent is less than 1 part by weight, it is difficult to cause a state change between the color forming state and the decoloring state of the image forming material. When the amount of the decoloring agent exceeds 200 parts by weight, the color formation of the image forming material becomes insufficient.

The matrix agent (binder resin or wax component) used in the present invention will be described. In the following, the ratio of the electron donating group in the matrix agent is 5% or less of the total number of carbon atoms even if not particularly described.

A styrene-based copolymer is preferred as a binder resin for a toner. Specific examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, and p-methylstyrene.
Ethylstyrene, 2,4-dimethylstyrene, pn-
Butylstyrene, p-tert-butylstyrene, p-
n-hexylstyrene, pn-octylstyrene, p
-N-nonylstyrene, pn-decylstyrene, p-
Examples include n-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene. These styrene monomers may be used alone or in combination of two or more. Vinyl monomers to be copolymerized include methyl methacrylate,
Ethyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, ethylhexyl methacrylate,
Lauryl methacrylate, stearyl methacrylate, vinyl acetate, vinyl propionate, methacrylonitrile,
Examples include dimethyl maleate, diethyl maleate, dimethyl fumarate, dibutyl fumarate, dimethyl itaconate, dibutyl itaconate, methyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl ether and the like. These vinyl monomers may be used alone or in combination of two or more.

Specific examples of the binder resin include styrene / n-butyl methacrylate, styrene / isobutyl methacrylate, styrene / ethyl acrylate, styrene / n-butyl acrylate, styrene / methyl methacrylate, styrene / glycidyl methacrylate, and styrene / dimethylaminoethyl. Methacrylate, styrene / diethylaminoethyl methacrylate, styrene /
Diethylaminopropyl acrylate, styrene 2-
Ethylhexyl acrylate, styrene / butyl acrylate-N- (ethoxymethyl) acrylamide, styrene / ethylene glycol methacrylate, styrene /
4-hexafluorobutyl methacrylate, styrene
Butadiene copolymer, acrylonitrile / acrylic rubber / styrene terpolymer, acrylonitrile / styrene / acrylate ester terpolymer, styrene / acrylonitrile copolymer, acrylonitrile / chlorinated polystyrene / styrene terpolymer, Acrylonitrile / ethylene vinyl acetate / styrene terpolymer, styrene /
Examples include p-chlorostyrene copolymer, styrene / propylene copolymer, styrene / butadiene rubber, styrene / maleic ester copolymer, styrene / maleic anhydride copolymer, and the like. The weight ratio of components such as butadiene, maleic ester and chloroprene is desirably 10% or less.

Polystyrene and polyacrylate may be blended and used. In this case, the polyacrylate may be a homopolymer or a copolymer. Alternatively, styrene or acrylate copolymerized with butadiene, maleic ester, chloroprene, or the like at a ratio of 10% or less may be used.

As the binder resin for the toner, an epoxy polymer, a urea resin, a melanin resin, an alkyd resin, an acrylic resin, a polyester, a polyamide resin, and a polyurethane may be blended. In this case, the ratio of these polymer components is desirably 15 wt% or less.

The polyester is synthesized by a reaction between a carboxylic acid and a polyhydric alcohol. As carboxylic acid monomers, terephthalic acid, fumaric acid, maleic acid, succinic acid,
Glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, brassic acid, pyromellitic acid, citraconic acid, glutaconic acid, mesaconic acid, itaconic acid, terraconic acid, phthalic acid, isophthalic acid, hemimelitic acid, melophanic acid Acids, trimesic acid, melophanic acid, planitic acid, trimellitic acid, melophanic acid, and derivatives thereof. As polyhydric alcohol,
Ethylene glycol, propylene glycol, butanediol, neopentyldiol, hexamethylenediol, heptanediol, octanediol, pentaglycerol, pentaerythritol, cyclohexanediol, cyclopentanediol, pinacol, glycerin, etherified diphenol, catechol, resorcinol, pyrogallol Benzenetriol, phloroglucin, benzenetetraol, and derivatives thereof. These monomers can be used alone or in combination of two or more. Further, two or more polyesters may be blended and used.

When polyester is used as the binder resin of the toner, the mixing ratio is preferably adjusted as follows according to the average molecular weight.

When the average molecular weight is 1,000 to 5,000, 30 to 95 wt%, and the average molecular weight is 5,000 to 10,000,
000, 30-90 wt%, average molecular weight 10,000
30-87 wt% in the case of 00-20,000, 30-85 wt% in the case of the average molecular weight of 20,000-100,000.
wt%, average molecular weight 100,000 to 1,000,000
In the case of, 30 to 80 wt%.

When an epoxy polymer is used as a binder resin for a toner, the mixing ratio is preferably adjusted as follows according to the average molecular weight.

When the average molecular weight is 1,000 to 5,000, 30 to 95 wt%, and the average molecular weight is 5,000 to 10,000,
000, 30-90 wt%, average molecular weight 10,000
30-87 wt% in the case of 00-20,000, 30-85 wt% in the case of the average molecular weight of 20,000-100,000.
wt%, average molecular weight 100,000 to 1,000,000
In the case of, 30 to 80 wt%.

In an erasable toner having a structure in which a dye component is separated by a microcapsule, a binder resin is used.
Polyvinyl acetate, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid resin, urea resin, polyamide, rosin, modified rosin, terpene resin, fatty acid or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax Etc. can also be used.

When the toner has a microcapsule structure, it is preferable to disperse a color former, a color developer or a decolorant in a core material (binder resin or wax component) in a master batch or the like. As a mixing / dispersing method, a high-speed dissolver, a roll mill, a ball mill, or another device may be used, for example, a wet dispersion method using a solvent, or a melt kneading method using a roll, a pressure kneader, an internal mixer, a screw-type extruder, or the like. Can be. As the mixing means, a ball mill, a V-type mixer, a Folberg, a Henschel mixer, or the like can be used.

The following method can be used as a method for producing microcapsules.

(1) Resin fine particles serving as a shell are attached to a core, and are fixed using a mechanochemical method.
In this case, a device such as a hybridizer (Nara Machine), mechanofusion (Hosokawa Micron), or a cryptotron (Kawasaki Heavy Industries) is used.

(2) Resin fine particles serving as a shell are adhered to the core and polymerized continuously (Insitz polymerization method). Examples of the polymerization method include emulsion polymerization, suspension polymerization, soap-free emulsion polymerization, seed polymerization, and dispersion polymerization. In the emulsion polymerization method and the suspension polymerization method, the thermal
It is preferable because a shell material having high mechanical strength can be obtained. However, it is not preferable to use an acid catalyst as the polymerization catalyst. This is because the remaining acid catalyst causes recoloring after decoloring.

Further, the obtained microcapsules may be mixed with a polymerizable monomer for providing a binder, and a polymerization initiator may be added to the mixture to cause a polymerization reaction to form a binder resin. The polymer chains are entangled with each other, entrapping microcapsules between the polymer chains. By such a method, a toner in which microcapsules are dispersed in a binder resin is generated.

(3) A binder resin, a dye component, and the like are added to a solvent to form a solution or slurry, which is then atomized by a spray dry method and dried. As a core,
Low melting point wax and the like are often used. The core is present in the shell as a solid, gel or liquid.

As the shell material of the microcapsule,
Polyether sulfone, polyether ketone, epoxy resin, polyethylene, polypropylene, polyphenylene ether, polyphenylene sulfite, polyalkylene oxide, polystyrene, polydivinylbenzene,
Polyphenol ether, nylon, polyamide, polyurethane, gelatin, polymethacrylic acid, polyimide,
Melanin resin, polyester, polyacrylic acid, polymethacrylonitrile, polysiloxane, polysulfide,
Examples include polycarbonate, polysulfone, polyisocyanate, and styrene / vinyl copolymer. These can be used alone or in combination of two or more.

When the microcapsules are broken by heating, a material that can be broken at 120 to 200 ° C. is selected. When the microcapsules are broken with a solvent, a material that is easily broken with a polar solvent is selected. Among the above-mentioned shell materials, a copolymer of styrene and a vinyl-based monomer having excellent transparency and mechanical strength is preferably used. Since the shell of the microcapsule needs to have pressure resistance against external pressure, it is desirable that the shell has excellent mechanical strength. However, if the mechanical strength is too strong, the shell of the microcapsule will not be broken when pressed in the fixing device, so that a copolymer having a weight ratio of styrene to vinyl monomer of 1: 0 to 1: 1 is used. preferable.

Specific examples of the styrene-based monomer include styrene, o-methylstyrene, m-methylstyrene and p-methylstyrene.
-Methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert
-Butylstyrene, pn-hexylstyrene, pn
-Octyl styrene, pn-nonyl styrene, pn
-Decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene and the like. These monomers can be used alone or in combination of two or more. Vinyl monomers include methyl methacrylate, ethyl methacrylate, isobutyl methacrylate,
Cyclohexyl methacrylate, ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, vinyl acetate, vinyl propionate, methacrylonitrile, dimethyl maleate, diethyl maleate, dimethyl fumarate, dibutyl fumarate, dimethyl itaconate, dimethyl itaconate Examples include dibutyl, methyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, and isobutyl ether. These vinyl monomers can be used alone or in combination of two or more.

The amount of the coloring compound and the color developing agent contained in the core of the microcapsule is 30 to 99 wt% (preferably 8%) in the color developing core not containing the decoloring agent.
8 to 98% by weight), and 5% in the color-developed core containing the decoloring agent.
It is from about 70% by weight (preferably from 10 to 60% by weight) and 5% by weight or less (preferably 0% by weight) in the core of the decoloring agent.

The shell thickness of the microcapsules is 0.01
It is formed in a range of 2 μm. However, the preferred range differs depending on the erasing method, the type of the erasing solvent, and the like. For example, when erasing using a low-solubility alcohol solvent, 0.01 to 0.3 μm, and when erasing using an ether-based solvent, 0.05 to 0.5 μm, a strongly soluble ketone-based solvent is used. In the case of erasing by using 0.1 to 1 μm in order to prevent bleeding or the like due to outflow of the decoloring agent,
When a halogen-based solvent having higher solubility than the ketone-based solvent is used, the thickness is preferably 0.5 to 2 μm.
Suitable particle size of the microcapsules varies depending on the use of the image forming material, but is 1 to 5 μm in the case of toner, thermal transfer ink, writing ink, and 100 to 100 μm or less in the case of ink for ink jet printer. 1000
It is preferably set to nm.

In an erasable toner in which a pigment component is separated by a phase separation structure using a polymer filler and a binder resin in combination, it is preferable to use a binder resin which does not reduce the image density of the toner. Specifically, the weight ratio of the polar monomer of the polystyrene and the copolymer in each case is 1
Styrene / acrylate copolymer, styrene / acrylic acid copolymer, styrene / methacrylic acid copolymer, styrene / epoxy-modified styrene copolymer, and a polyester resin having a relatively small content of a polar group, which is 5% by weight or less Are used. As the polymer filler, those having a glass transition point or a softening point higher than that of the binder resin by 20 ° C. or more (preferably 50 ° C. or more) are selected from the above-mentioned ones.

The binder resin of the toner preferably has a softening point of 95 to 160 ° C. and a glass transition point of 50 to 80 ° C. The softening point was measured using a flow tester (CFT-500 manufactured by Shimadzu Corporation) and the nozzle: 1.0 m
mφ × 10.0 mm, load: 30 kg · f, heating rate:
Under the conditions of 3 ° C./min and the amount of the sample: 1.0 g, the temperature is measured as the temperature (T _1/2 ) when the amount of the sample flowing out reaches half. The glass transition point is determined as the temperature of the shoulder value after melt quenching by DSC.

When the present invention is applied to a toner, a wax component or the like may be blended to control the fixing property. Examples of the wax component include long-chain aliphatic alcohols having 10 or more carbon atoms, long-chain aliphatic ketones having 10 or more carbon atoms, low-molecular-weight polypropylene, low-molecular-weight polyethylene, low-molecular-weight polybutylene, low-molecular-weight polyalkanes, and modified products thereof. Is mentioned. These wax components can be used alone or in combination of two or more. The wax component preferably has a weight average molecular weight of 10 ² to 10 ⁵ , more preferably 10 ² to 10 ⁴ . In addition, aliphatic carboxylic acid wax represented by stearic acid wax, carnauba wax containing fatty acid, rice wax containing free carboxylic acid in ester of higher fatty acid and higher alcohol, and synthetic wax containing coal-based synthetic wax containing polymer wax acid Montan wax, acid amide, liquid paraffin, sasol wax, caster wax, chlorinated paraffin, etc. have an acid value. These waxes are saponified with calcium hydroxide to reduce the acid value to 10 or less. The amount of the wax component added is 0.1 to 3 with respect to 100 parts by weight of the toner.
It is preferably 0 parts by weight, more preferably 0.5 to 15 parts by weight. In the toner to be heat-fixed, the wax is added in an amount of 5 parts by weight so as to impart a releasing property from the fixing roll. For electrophotographic toner that performs pressure fixing,
The main component of the core of the microcapsule structure is made of wax.

The charge control agent used in the erasable toner of the present invention may be a negative charge control agent or a positive charge control agent. As the negative charge control agent, a metal chelate of alkyl salicylic acid, a metal chelate of dicarboxylic acid,
Examples include chlorinated polyesters, polyesters with excess acid groups, chlorinated polyolefins, metal salts of fatty acids, and fatty acid soaps. More specifically, E-84 of Orient Chemical which is a zinc salicylate compound, N-1, N-2 and N-3 of Nippon Kayaku which is a phenolic compound, and styrene-
FCA-1001 by Fujikura Kasei, a sulfonic acid resin
N, LR-147 of Nippon Carlit Co., Ltd., and the like. Examples of the positive charge control agent include quaternary ammonium salts, guanamine derivatives, amine compounds, and other nitrogen compounds. More specifically, Hodogaya Chemical's T
P-302 (CAS # 116810-46-9) and TP-415 (117342-25-2); P-51 of Orient Chemical, a quaternary amine compound; AFP-B of Orient Chemical, a polyamine oligomer; styrene -FCA-201PB of Fujikura Kasei, which is an acrylic quaternary ammonium salt-based resin. Of these, a colorless or transparent charge control agent is used.

In the erasable toner of the present invention, if necessary, an external additive for controlling fluidity, storage stability, anti-blocking property, photoreceptor polishing property and the like may be blended. As the external additive, silica fine particles, metal oxide fine particles, a cleaning aid and the like are used. Examples of the silica fine particles include silicon dioxide, sodium silicate, zinc silicate, and magnesium silicate. Examples of the metal oxide fine particles include zinc oxide, magnesium oxide, zirconium oxide, strontium titanate, and barium titanate. Examples of the cleaning aid include fine resin powders such as polymethyl methacrylate, polyvinylidene fluoride, and polytetrafluoroethylene. It is preferable that these external additives have been subjected to surface treatment such as hydrophobization. In the case of negative charging, a treating agent such as a silane coupling agent, a titanium coupling agent, or silicone oil is used. In the case of positive charging, a treating agent such as an aminosilane-based silicone oil having an amine in a side chain is used. The addition amount of these external additives is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 3.0 parts by weight, based on 100 parts by weight of the toner. As the silica fine particles, particles having a number average primary particle diameter of 10 to 20 nm are often used, and in addition, particles having a number average particle diameter of 100 nm are also used.
For materials other than silica, the number average particle size is 0.05 to 3 μm.
m particles are used.

The particle size range of the erasable toner is such that the volume average diameter is 6 to 20 μm, the content of particles having a particle size of 5 μm or less in the number distribution is 2 to 20% by number, and the content of particles having a volume distribution of 5 μm or less is 0 to 0%. 5% by volume, 20 in volume distribution
It is preferable that the content of the particles having a size of not less than μm is 0 to 5% by volume. These values are measured on a Coulter Multisizer (Coulter).

The conductivity of the erasable toner is 10 ¹¹ to 10
¹⁶ Ω · cm, and more preferably 10 ¹³ to 10 ¹⁵ Ω · cm. In the case of two-component development, iron powder, ferrite, magnetite as a carrier and resin-coated with silicone, acrylic, or the like are used. For iron powder, 10 ⁹ Ω · cm or less, ferrite of about 10 ⁶ to 10 ¹⁵ Ω · cm, magnetite At least 10 ¹³ Ω · cm, and disperse the magnetic powder in the resin.
In the case of pulverized to about μm, the resistance is preferably 10 ¹³ Ω · cm or more. The conductivity is as follows: the toner has a diameter of 20 mm and a thickness of 1 mm
, And applied with a potential of 1 V · 1 kHz for measurement.

In the present invention, it has been found that a good erased state can be stably obtained by adjusting the pH of the image forming material to 7 or more. In order to adjust the pH of the image forming material to about 8, a basic substance is used. The basic substance is not particularly limited, and may be an inorganic compound or an organic compound. These basic compounds may be added directly to the image forming material, or may be added after microencapsulation.

Suitable inorganic compounds include calcium chloride, potassium hydroxide, calcium hydroxide, sodium hydroxide, barium hydroxide, magnesium hydroxide, ammonium carbonate, potassium carbonate, calcium carbonate, sodium carbonate, magnesium carbonate, hydrogen carbonate. Examples include ammonium, potassium bicarbonate, sodium bicarbonate, alkali metal borates, tripotassium phosphate, dipotassium hydrogenphosphate, calcium phosphate, trisodium phosphate, and disodium hydrogenphosphate.

Suitable organic compounds include primary to tertiary
And quaternary ammonium salts and quaternary ammonium salts. Examples of the counter ion of the quaternary ammonium salt include a hydroxyl ion, a halogen ion, and an alkoxide ion.

Examples of the non-aromatic amine or ammonium salt include those having an aliphatic hydrocarbon group having 1 to 50 carbon atoms or an alicyclic hydrocarbon group having 1 to 50 carbon atoms. These hydrocarbon groups are vinyl, ethynylene, ethynyl, oxy, oxycarbonyl, thiocarbonyl, dithiocarbonyl, thio, sulfinyl, sulfonyl, carbonyl, hydrazo,
It may be substituted with at least one substituent selected from azo group, azide group, nitrilo group, diazoamino group, imino group, urea bond, thiourea bond, amide bond, urethane bond and carbonyldioxy group.

Examples of the aromatic amine or ammonium salt include benzene ring, biphenyl ring, naphthalene ring, tetralone ring, anthracene ring, phenanthrene ring, indene ring, indane ring, pentalene ring, azulene ring, heptalene ring, fluorene ring and the like. And those having an aromatic ring. These aromatic rings may be substituted with an aliphatic hydrocarbon group having 1 to 50 carbon atoms or an alicyclic hydrocarbon group having 1 to 50 carbon atoms. Further, these hydrocarbon groups may be substituted with the substituents described above.

Examples of the cyclic amine include aziridine, azetidine, pyrroline, pyrrolidine, indoline, pyridine,
Piperidine, hydropyridine, quinoline, isoquinoline, tetrahydroquinoline, tetrahydroisoquinoline, acridine, phenanthridine, phenanthroline, pyrazole, benzimidazole, pyridazine, pyrimidine, pyrazine, imidazole, histamine, decahydroquinoline, pyrazoline, imidazoline, imidazolidine, piperazine , Cinnoline, phthalazine, quinazoline, quinosaline, dihydrophenazine, triazole, benzotriazole, triazine, tetrazole,
Pentamethylenetetrazole, tetrazine, purine, pteridine, carboline, naphthyridine, indolizine,
Quinolidine, quinuclidine, oxazole, oxazolidine, benzoxazole, isoxazole, anthranyl, oxazine, oxazoline, thiazole, thiazolidine, benzothiazole, benzothiazoline, isothiazole, thiazine, azoxime, furazane, oxadiazine, thiadiazole, benzothiadiazole, thiadiazine, dithiazine, Examples include morpholine, hexamethylenetetramine, diazabicycloundecene and the like.

Organic basic substances that can be used in addition to the above include alkali metal salts of alcohols, alkaline earth metal salts of alcohols, amidines, guanidines, aminoguanidines, ureas, thioureas, semicarbazides, thiosemicarbazides, and carbonocarbonates. Hydrazide.

When the present invention is applied to a liquid ink, a non-polar wax or a non-polar or low-polar resin (polymer or oligomer) can be suitably used as a matrix agent. Examples of the non-polar wax include higher alcohols (eg, 1-docosanol, 1-eicosanol, stearyl alcohol), higher ketones (eg, stearone, 14-heptacosanone), higher aliphatic esters (eg, stearyl alcohol laurate, docosanol stearate, etc.). ). The acid value is preferably 10 or less. As the wax, those having a weight average molecular weight of 10 ² to 10 ⁵ , more preferably 10 ² to 10 ⁴ are preferably used. Examples of the nonpolar or low-polarity resin include low-molecular-weight polypropylene, low-molecular-weight polyethylene, low-molecular-weight polybutylene, low-molecular-weight polyalkane, and low-molecular-weight polystyrene.

As the organic solvent having a boiling point of 150 ° C. or higher (preferably 180 ° C. or higher) used in the fourth image forming material of the present invention, a non-polar or low-polarity organic solvent is suitable. Non-polar organic solvents include long-chain saturated aliphatic hydrocarbons (dodecane, tetradecane, hexadecane,
Octadecane, eicosan, docosan, tetracosan,
Liquid paraffin), long chain unsaturated aliphatic hydrocarbons (dodecene, tetradecene, hexadecene, octadecene,
Eicosene, dococene, tetracosene, etc.), alicyclic hydrocarbons (cycloheptane, cyclooctane, etc.), chain terpenes (myrcene, ocimene, etc.), and cyclic terpenes (menten, limonene, terpinolene, terpinene, etc.). Examples of low polar organic solvents include alkyl alkanols (such as 2-butyl octanol, 2-butyl decanol, 2-hexyl decanol, 2-octyl decanol, and 2-decyl dodecanol), and long-chain aliphatic alcohols (such as octanol and decanol). ), Alicyclic alcohols (such as cyclohexanol), polyhydric alcohols (such as ethylene glycol, propylene glycol, brylene glycol, glycerin, and pentaglycerol), and long-chain aliphatic esters (ethyl decanoate, ethyl laurate, butyl laurate) Butyl lactate).

The organic solvent used in the fifth image forming material of the present invention may have at least one electron donating group. Further, an organic solvent having a high vaporization rate is preferable, contrary to the organic solvent used in the fourth step, because the color change is fast. Such organic solvents include solvents having relatively low polarity, such as alcohols (ethanol, isopropyl alcohol, etc.) and aliphatic esters (methyl acetate, methyl butyrate, etc.), acetone, methyl ethyl ketone, cyclohexanone, dihexanone, etc. A wide range of solvents can be selected, such as solvents such as ethoxymethane and dimethylformamide.

In the case of liquid ink, the above-mentioned polymer filler is used. The content of the polymer filler in the liquid ink varies depending on the application of the ink, and is 0.5 to 10% by weight in the case of an inkjet ink, 3 to 20% by weight in the case of stationery ink, and 3 to 20% by weight of an offset ink. Is 5 to 30 wt%, and 20 to 60 in the case of viscous ink.
A range of wt% is desirable.

In the case of a thermal transfer ink ribbon, a soft resin having a relatively low molecular weight and a low glass transition point is preferably used as the binder resin in consideration of the thermal transferability of the resin composition. Specifically, polyethylene, polypropylene, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, ethylene / maleic anhydride copolymer, ethylene / acrylate / maleic anhydride copolymer, propylene / acetic acid Vinyl copolymer, propylene / ethyl acrylate copolymer, propylene / maleic anhydride copolymer, propylene / acrylate ester
Maleic anhydride copolymer, butylene / vinyl acetate copolymer, butylene / butyl acrylate copolymer, butylene / maleic anhydride copolymer, butylene / acrylic ester / maleic anhydride copolymer, and the like. In addition, a styrene-acrylate copolymer having a relatively low molecular weight or a polyester resin having a relatively low molecular weight and a low glass transition point can be used. On the other hand, as a polymer filler,
Among the above, except for the polyolefin resin, a resin having more polar groups than the binder resin can be suitably used.

In the present invention, the image recording medium may function as a polymer filler. That is, at the time of heating or contact with a solvent, one of the color-forming compound and the developer interacts (adheres, adsorbs, or bonds) with the image recording medium to exhibit at least a part of the erasing function. As the image forming material, it is preferable to use a material containing a color former, a color developer, and more preferably a decolorant. By doing so, the absolute amount of the decoloring agent can be reduced, the amount of the matrix agent in the image forming material can be increased, and the dispersibility of the components can be increased.

In the present invention, in order to erase the colored image forming material, there are a method of erasing the image forming material by heating and melting, and a method of erasing the image forming material by contacting it with a solvent.

In the method of heating the image forming material, any heating means such as a thermal printer head (TP)
H), a laser head, a thermal bar, a hot stamp, a heat roller, a heat gun, a hot air blower, a heating lamp and the like can be applied.

Examples of a heat erasing device applicable to erasing an image forming material containing a decoloring agent by heat include a rapid cooling thermal printer head (TPH), a laser beam head, a thermal bar, and the like. Various heating devices such as a hot stamp, a heat roller, a heat gun, a hot air blower, lamp heating, or a large plant combining these can be applied.

In the method in which the image forming material is brought into contact with a solvent, the paper is immersed in the solvent or the solvent is sprayed on the paper. As a means for this, a roller for dipping the paper in the solvent contained in the container, a spray nozzle for spraying the solvent on the paper, a nozzle for dropping the solvent on the paper, a gravure roller for supplying the solvent to the paper, and the like are used.

In order to obtain a good erasing state after erasing the solvent, it is effective to further heat to a temperature higher than the melting point of the decoloring agent. That is, the unerased portion of the image recording medium is reduced by heating, and a high-quality erased state can be obtained. At the same time, the solvent remaining on the image recording medium can be removed. As the heating means, hot air, infrared lamp, heat roller, hot press, thermal printer head (T
PH) and a thermal bar. Further, it is preferable to provide a means for collecting the used solvent in these apparatuses.

As shown in FIG. 10, erasing or writing / erasing may be performed using a pen-type stationery. FIG.
(A) shows an example of the structure of a correction (erase) pen, and (B) shows an example of the structure of a writing / erasing pen.

The correction (erase) pen shown in FIG. 10A has a pen body 51 containing an erase solution 52. The pen body 51 has two different thicknesses for fine correction and normal correction.
Book felts 54a and 54b are inserted. Each of the felts 54a and 54b is provided with caps 55a and 55b for preventing drying.

In the writing / erasing pen shown in FIG. 10B, an erasable ink 53 and an erasing solution 52 are accommodated in a pen body 51 and separated by a separation wall 56, so that both are not mixed. . A writing felt 54c and a correction felt 54d are inserted into the pen body 51. The felts 54c and 54d are provided with caps 55a and 55b for preventing drying.

The correcting (erasing) pen can erase toner, liquid ink, and solid ink (ink ribbon, colored pencil, crayon, etc.) produced by the image forming material of the present invention. Further, depending on the selection of the erasing solution, it is also possible to selectively erase only a part of the ink.

The solvent used in the elimination method using the solvent is as follows:
(A) It is preferable that the material has a property of assisting the formation of a hydrogen bond between the color developer and the decolorant, and (B) the property of having high affinity with the binder and easily penetrating into the inside of the image forming material. It is preferred to have. The solvent satisfying the above property (A) can be used alone. Further, two or more solvents may be mixed to satisfy the above two properties.

Examples of the solvent having both the properties (A) and (B) include ethers, ketones and esters. Specific examples include saturated ethers such as ethyl ether, ethyl propyl ether, ethyl isopropyl ether, isopentyl methyl ether, butyl ethyl ether, dipropyl ether, diisopropyl ether, ethyl isopentyl ether, dibutyl ether, dipentyl ether, diisopentyl ether. Unsaturated ethers such as ethyl vinyl ether, allyl ethyl ether, diallyl ether, ethyl propargyl ether; ethers of dihydric alcohols such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 1,2-dimethoxy Ethane, 1,2-diethoxyethane, 1,2-dibutoxyethane; cyclic ethers such as oxetane,
Tetrahydrofuran, tetrahydropyran, dioxolan, dioxane, trioxane; saturated ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, diethyl ketone, isopropyl methyl ketone, butyl methyl ketone, ethyl propyl ketone, isobutyl methyl ketone, pinacolone, methyl pentyl ketone, butyl ethyl Ketone, dipropyl ketone, diisopropyl ketone, hexyl methyl ketone, isohexyl methyl ketone, heptyl methyl ketone, dibutyl ketone; unsaturated ketones such as ethylidene acetone, allyl acetone,
Mesityl oxide; cyclic ketone such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone; ester such as ethyl formate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, ethyl acetate, isopropyl acetate, acetic acid Propyl, butyl acetate, isobutyl acetate, pentyl acetate,
Isopentyl acetate, sec-amyl acetate, hexyl acetate, allyl acetate, 2-methoxyethyl acetate, 2-
Ethoxyethyl acetate, 1,2-diacetoxyethane, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, butyl propionate, pentyl propionate, isopentyl propionate, sec-amyl propionate, 2-methoxypropyl Acetate, 2-ethoxypropyl acetate, methyl butyrate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, pentyl butyrate, isopentyl butyrate, sec-amyl butyrate, methyl isobutyrate, ethyl isobutyrate, propyl isobutyrate, isopropyl isobutyrate, Butyl isobutyrate, pentyl isobutyrate, isopentyl isobutyrate, sec-amyl isobutyrate, methyl valerate, ethyl valerate, propyl valerate, isopropyl valerate, butyl valerate, methyl valerate, Kusasan ethyl, propyl valerate,
Isopropyl valerate, butyl valerate, methyl hexanoate, ethyl hexanoate, propyl hexanoate, isopropyl hexanoate and the like. As a solvent other than the above, methylene chloride, γ-butyrolactone, β-propiolactone, n-methylpyrrolidinone, dimethylformamide,
Examples include dimethylacetamide and dimethylsulfoxide (first group). These may be used alone or as a mixture of two or more. When a mixed solvent is used, the mixing ratio can be set arbitrarily.

Solvents having the property (A) but having a low affinity for the binder include, for example, water, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, pentyl alcohol, 2-pentyl alcohol,
3-pentyl alcohol, isopentyl alcohol, 1
-Hexanol, 2-hexanol, 3-hexanol, cyclopentanol, cyclohexanol, ethylene glycol, propylene glycol, butylene glycol, glycerin and the like (second group).

Solvents which do not have the property (A) but have a high affinity for the binder include, for example, toluene, ethylbenzene, propylbenzene, cumene, butylbenzene, isobutylbenzene, sec-butylbenzene, pentylbenzene, diethylbenzene, diethylbenzene, and the like. Mesitylene, xylene, cresol, ethylphenol, dimethoxybenzene, dimethoxytoluene, benzyl alcohol, tolyl carbinol, cumyl alcohol, acetophenone,
Propiophenone, hexane, pentane, heptane, octane, cyclohexane, cyclopentane, cycloheptane, cyclooctane, petroleum fractions (petroleum ether, benzine, etc.) (Group 3).

As mentioned above, the first group of solvents can be used alone satisfactorily. The second group of solvents may be used alone or may be mixed with the first group of solvents. In this case, since both groups of solvents have erasing ability, they can be used at an arbitrary mixing ratio. When using a mixed solvent of the second group of solvents and the third group of solvents, the mixing ratio of the two is not particularly limited as long as sufficient erasing ability is obtained, but the third group of solvents should be 20 to 80 wt%. Is preferred. The third group of solvents may be used as a mixture with the first group of solvents. In this case, the third group of solvents may be 90 wt% or less. Further, the solvents of the first to third groups may be mixed and used.
In this case, the content of the third group of solvents is preferably set to 80 wt% or less.

If a natural material such as ethyl butyrate (pineapple oil) having a very low effect on the environment is used as a solvent, no problem will occur during disposal even if the solvent remains. Further, in order to efficiently decolor the image forming material, the solvent may be heated in advance. In this case, the temperature of the solvent is preferably in the range of 40 to 150 ° C.

[0149]

Embodiments of the present invention will be described below.

In the following examples, copy paper (NEUSIEEDLE) which is normally used in Europe is used.
R, 500 BLATT, pH = 9.4). The reflection density of the paper was measured with a Macbeth densitometer.

Example 1 As a color-forming compound, 2-anilino-6- (N-ethyl-
3 parts by weight of N-isobutylamino) -3-methylfluorane, 2 parts by weight of 2,3,4-trihydroxybenzophenone as a developer, and polystyrene 9 as a binder resin
4 parts by weight, charge control agent (Orient Chemical Co., E-84)
One part by weight was mixed and sufficiently kneaded using a kneader.
The kneaded product was pulverized by a pulverizer to obtain a black powder having an average particle size of 10 μm.

On the other hand, styrene / butyl acrylate (acrylate content 30 wt%) 87 as a polymer filler
10 parts by weight of cholic acid as a decolorizing agent, 2 parts by weight of stearone as a wax component, and 1 part by weight of a charge control agent (E-84, Orient Chemical Co., Ltd.) were mixed and sufficiently kneaded using a kneader. The kneaded product was pulverized by a pulverizer to obtain a colorless powder having an average particle size of 1 μm.

Each of the above powders was mixed with 60 parts and 40 parts.
Parts by weight of hydrophobic silica 1 wt.
%, And stirred with a Henschel mixer to produce a black electrophotographic toner.

The prepared toner was placed in a toner cartridge of a copying machine, and an image for evaluation was copied on copy paper. The reflection density of the formed image was about 1.0. After immersing this paper in 2-butanone to erase the image, it was air-dried. The reflection density of the paper after the image was erased was 0.07, and a good erased state was obtained. Even after the paper from which the image was erased was allowed to stand at 60 ° C. for 300 hours, there was no change in the reflection density. Further, when erasing and overwriting were repeated 10 times, an image almost similar to the first image could be obtained.

Example 2 As a color-forming compound, 2-anilino-6- (N-ethyl-
N-isobutylamino) -3-methylfluoran 2.5
Parts by weight, 1.5 parts by weight of propyl gallate as a developer,
One part by weight of rice alcohol as a wax component, 15 parts by weight of cholic acid as a decolorizing agent, 79 parts by weight of polystyrene as a binder resin, and 1 part by weight of a charge control agent (LR-147) were mixed and kneaded sufficiently using a kneader. . The kneaded material was pulverized by a pulverizer to obtain a powder having an average particle size of 8 μm.

As a polymer filler, 5 wt% of polyhydroxyethyl methacrylate having a softening point of about 50 ° C. was added to acetone.
%, The charge control agent (LR-147) and the powder obtained in the above step were added, stirred, and dried by spray drying. 1 wt% of hydrophobic silica was externally added to this powder to prepare a black electrophotographic toner. In this way, a microcapsule type erasable toner whose surface was coated with the polymer filler was produced.

The prepared toner was placed in a toner cartridge of a copying machine, and an image for evaluation was copied on copy paper. At this time, the fixing temperature was set to 140 ° C. The reflection density of the formed image was about 1.0. The paper was immersed in diethoxyethane to erase the image, and then air-dried. The reflection density of the paper after erasing the image was 0.06, and blurring of the image was locally observed. This bleeding could be erased by passing the paper through a heat roller, and a good erased state was obtained. Even after the paper from which the image was erased was allowed to stand at 60 ° C. for 300 hours, there was no change in the reflection density.

Next, a microcapsule type erasable toner was prepared in the same manner as described above except that 1% by weight of cholic acid as a decolorizing agent was added to the acetone solution of polyhydroxyethyl methacrylate prepared above. In the same manner as described above, after an image was formed using the prepared toner, the image was erased. In this case, the reflection density of the paper after erasing the image is 0.1.
05, indicating that the erased state was better. Even after the paper from which the image was erased was allowed to stand at 60 ° C. for 300 hours, there was no change in the reflection density. In addition, 10
As a result, an image almost similar to the first image could be obtained.

Example 3 As a coloring compound, 2-anilino-6- (N-ethyl-
3 parts by weight of N-isobutylamino) -3-methylfluorane, 2 parts by weight of 2,3,4-trihydroxybenzophenone as a color developer, 10 parts by weight of cholic acid as a decolorant, 84 parts by weight of polystyrene as a binder resin, 1 part by weight of a charge control agent (Orient Chemical Co., E-84) is mixed,
The mixture was sufficiently kneaded using a kneader. The kneaded product was pulverized by a pulverizer to obtain a black powder having an average particle size of about 8 μm.

On the other hand, 87 parts by weight of styrene / butyl acrylate having an acrylate content of 30 wt% as a polymer filler, 10 parts by weight of cholic acid as a decolorizing agent, 2 parts by weight of stearone as a wax component, and a charge controlling agent (Orient Chemical Co., Ltd. E-84) 1 part by weight was mixed and sufficiently kneaded using a kneader. The kneaded product was pulverized by a pulverizer to obtain a colorless powder having an average particle size of 1 μm.

Each of the above powders was mixed with 60 parts and 40 parts.
Parts by weight of hydrophobic silica 1 wt.
%, And stirred with a Henschel mixer to produce a black electrophotographic toner.

The prepared toner was placed in a toner cartridge of a copying machine, and an image for evaluation was copied on copy paper. The reflection density of the formed image was about 1.0. After immersing this paper in 2-butanone to erase the image, it was air-dried. The reflection density of the paper after erasing the image was 0.06, and neither toner flow nor image bleeding was observed. Even after the paper from which the image was erased was allowed to stand at 60 ° C. for 300 hours, there was no change in the reflection density. In addition, erase and overwrite
After repeating 0 times, an image almost similar to the first image could be obtained.

Example 4 6 parts by weight of 2-chloro-6- (dimethylamino) fluorane as a color-forming compound, 4 parts by weight of methyl gallate as a color developer, 89 parts by weight of an amorphous polyolefin as a binder resin, charge control 1 part by weight of the agent (LR-147) was mixed and kneaded sufficiently using a kneader. The kneaded product was pulverized by a pulverizer to obtain a red powder having an average particle size of about 1 μm.

60 parts by weight of this powder and styrene / butyl acrylate (acrylate content 3
(0 wt%), 38 parts by weight, 1 part by weight of polyethylene wax as a wax component, and 1 part by weight of a charge control agent (LR-147) were mixed and kneaded sufficiently using a kneader. The kneaded product was pulverized by a pulverizer to obtain a red powder having an average particle size of about 10 μm. Hydrophobic silica 1 for the obtained powder
wt% was externally added and stirred with a Henschel mixer to produce a red electrophotographic toner.

The prepared toner was placed in a toner cartridge of a copying machine, and an image for evaluation was copied on copy paper. The reflection density of the formed image was about 1.0. The paper was immersed in a mixed solvent of 2-butanone / toluene to erase the image, and then air-dried. The reflection density of the paper after erasing the image was 0.10, and a slight afterimage was observed, but no toner flow or image bleeding was observed. This afterimage could be erased by passing the paper through a heat roller, and a good erased state was obtained. Remove the paper from which the image was erased at 60 ° C for 30
After standing for 0 hours, there was no change in the reflection density.

Next, a toner was prepared in the same manner as described above except that 5 parts by weight of 38 parts by weight of styrene / butyl acrylate as a polymer filler was replaced with cholic acid as a decolorizing agent. In the same manner as described above, after an image was formed using the prepared toner, the image was erased. In this case, the reflection density of the paper after erasing the image was 0.07, and the erasing state was better. Even after the paper from which the image was erased was allowed to stand at 60 ° C. for 300 hours, there was no change in the reflection density. Further, when erasing and overwriting were repeated 10 times, an image almost similar to the first image could be obtained.

Example 5 2-N, N-dibenzylamino-6 was used as a color-forming compound.
-6 parts by weight of dimethylaminofluoran, 4 parts by weight of methyl gallate as a color developer, a mixture of 8 parts by weight of cholic acid, 1 part by weight of sitosterol and 1 part by weight of D-glucose as a decolorizer, and an amorphous binder resin Polyolefin 7
9 parts by weight and 1 part by weight of the charge control agent (LR-147) were mixed and kneaded sufficiently using a kneader. The kneaded product was pulverized by a pulverizer to obtain a green powder having an average particle size of about 1 μm.

60 parts by weight of this powder and styrene / butyl acrylate (acrylate content 3
(0 wt%), 38 parts by weight, 1 part by weight of polyethylene wax as a wax component, and 1 part by weight of a charge control agent (LR-147) were mixed and kneaded sufficiently using a kneader. The kneaded product was pulverized by a pulverizer to obtain a green powder having an average particle size of about 10 μm. Hydrophobic silica 1 for the obtained powder
wt% was externally added and stirred with a Henschel mixer to produce a green electrophotographic toner.

The prepared toner was placed in a toner cartridge of a copying machine, and an image for evaluation was copied on copy paper. The reflection density of the formed image was about 1.0. The paper was immersed in a mixed solvent of 2-butanone / toluene to erase the image, and then air-dried. The reflection density of the paper after the image was erased was 0.08, and an afterimage was slightly observed, but neither toner flow nor image bleeding was observed. This afterimage could be erased by passing the paper through a heat roller, and a good erased state was obtained. Remove the paper from which the image was erased at 60 ° C for 30
After standing for 0 hours, there was no change in the reflection density.

Next, a toner was prepared in the same manner as described above, except that 5 parts by weight of 38 parts by weight of styrene / butyl acrylate as a polymer filler was replaced with cholic acid as a decolorizing agent. In the same manner as described above, after an image was formed using the prepared toner, the image was erased. In this case, the reflection density of the paper after erasing the image was 0.06, and the erasing state was better. Even after the paper from which the image was erased was allowed to stand at 60 ° C. for 300 hours, there was no change in the reflection density. Further, when erasing and overwriting were repeated 10 times, an image almost similar to the first image could be obtained.

Example 6 As a color-forming compound, 3-diethylamino-6-methyl-
3 parts by weight of 7-xyridinofluorane, 2 parts by weight of ethyl gallate as a color developer, and 1 part by weight of polyethylene wax as a wax component were mixed and melted to prepare a uniform composition. 40 g of this composition was mixed with 0.5 g of hexamethylene bischloroformate and melted. This mixture was added dropwise to 200 g of an aqueous solution containing 5% by weight of gelatin and 1% by weight of ethyl gallate, and stirring was continued to form fine droplets. Furthermore, 3 g of hexamethylene diamine was added to 50 g of water.
Was gradually added dropwise to the above aqueous solution while stirring at 40 ° C. for 5 hours. As a result, hexamethylenebischloroformate reacts with hexamethylenediamine at the interface between the microdroplets of the pigment component and water to synthesize an insoluble solid polyurethane, and the microcapsules in which the pigment component is covered with a polyurethane shell are formed. Generated. The microcapsules were filtered from this suspension and dried.

On the other hand, as a decoloring agent, 90 parts by weight of cholic acid,
10 parts by weight of polystyrene as a binder resin, 60
A solution was prepared by dissolving the mixture in an ethanol / toluene mixed solvent heated to ℃. This solution was sprayed to prepare a decolorizing agent microcapsule having an average particle size of about 0.5 μm.

6 parts by weight of a microcapsule of a pigment component, 1 part by weight of a polyethylene wax as a wax component, 15 parts by weight of a microcapsule of a decolorant, 77 parts by weight of a styrene / butyl acrylate copolymer (acrylate content: 40 wt%) as a binder resin And 1 part by weight of a charge controlling agent (Nippon Kayaku Co., Ltd., E-1), and kneaded sufficiently using a kneader. The kneaded product was pulverized by a pulverizer to obtain a powder having an average particle size of about 10 μm. 1 wt% of hydrophobic silica was externally added to the obtained powder to prepare a black electrophotographic toner.

The prepared toner was placed in a toner cartridge of a copying machine, and an image for evaluation was copied on copy paper. The reflection density of the formed image was about 1.2. The paper was passed through a heat roller at 200 ° C. to break the microcapsules by heat. The paper was further immersed in a mixed solvent of diethoxyethane and isopropyl alcohol to erase the image, followed by air drying. The reflection density of the paper after erasing the image is 0.06,
No toner flow or image bleeding was observed. Even after leaving the paper with the image erased at 60 ° C. for 300 hours,
There was no change in the reflection density.

Example 7 As a color-forming compound, 3-diethylamino-6-methyl-
3 parts by weight of 7-xylidinofluorane, 2 parts by weight of propyl gallate as a color developer, and 1 part by weight of polyethylene wax as a wax component were mixed and melt-mixed to prepare a uniform composition. 40 g of this composition was mixed with 0.5 g of hexamethylene bischloroformate and melted. This mixture was mixed with 5% by weight of gelatin and 1% by weight of ethyl gallate.
Was added dropwise to 200 g of an aqueous solution containing, and stirring was continued so as to become fine droplets. Further, stirring was continued at 40 ° C. for 5 hours while a solution of 3 g of hexamethylenediamine dissolved in 50 g of water was gradually dropped into the above aqueous solution. As a result, hexamethylenebischloroformate reacts with hexamethylenediamine at the interface between the microdroplets of the pigment component and water to synthesize an insoluble solid polyurethane, and the pigment component is coated with a polyurethane shell. About 0.5 μm microcapsules were produced. The microcapsules were filtered from this suspension and dried.

Styrene butyl acrylate (acrylate content 40 wt%) 10 wt% as a polymer filler
And 50% acetone solution of cholic acid
To 0 parts by weight, 3 parts by weight of the microcapsules obtained above, 1 part by weight of a charge control agent (Nippon Kayaku Co., Ltd., E-1), and 1 part by weight of polypropylene wax as a wax component were dispersed. This dispersion was sprayed to obtain a powder having an average particle size of about 10 μm. 1 wt% of hydrophobic silica was externally added to this powder to prepare a black electrophotographic toner.

The prepared toner was placed in a toner cartridge of a copying machine, and an image for evaluation was copied on copy paper. The reflection density of the formed image was about 1.2. The paper was passed through a heat roller at 200 ° C. to break the microcapsules by heat. The papers were further immersed in diethoxyethane to erase the image, and then air-dried. The reflection density of the paper after the image was erased was 0.05, and a good erased state was obtained. Even after the paper from which the image was erased was allowed to stand at 60 ° C. for 300 hours, there was no change in the reflection density. Further, when erasing and overwriting were repeated 10 times, an image almost similar to the first image could be obtained.

Example 8 As a color-forming compound, 3-diethylamino-6-methyl-
3 parts by weight of 7-xyridinofluoran, 2 as a color developer
2 parts by weight of 3,4-trihydroxyacetophenone, a mixture of cholic acid and cholesterol (weight ratio 9:
1) 25 parts by weight and 5 parts by weight of a polypropylene wax as a wax component were mixed and melted to prepare a uniform composition. 40 g of this composition was mixed with 0.5 g of hexamethylene bischloroformate and melted. This mixture was added dropwise to 200 g of an aqueous solution containing 5% by weight of gelatin and 1% by weight of ethyl gallate, and stirring was continued to form fine droplets. Further, a solution in which 3 g of hexamethylenediamine was dissolved in 50 g of water was gradually dropped into the above aqueous solution.
Stirring was continued at 40 ° C. for 5 hours. As a result, hexamethylenebischloroformate reacts with hexamethylenediamine at the interface between the fine droplets of the pigment component and water to synthesize a solid polyurethane, and the pigment component is coated with a polyurethane shell to have an average particle size of about 0. 0.5 μm microcapsules were produced. The microcapsules were filtered from this suspension and dried.

20 wt% of styrene / butyl acrylate (acrylate content: 40 wt%) as a polymer filler
% Acetone solution, 500 parts by weight of the microcapsules obtained above, 3 parts by weight of a charge controlling agent (Nippon Kayaku Co., Ltd., E-
1) 1 part by weight of 1 part by weight of polyethylene wax as a wax component was dispersed. This dispersion was sprayed to obtain a powder having an average particle size of about 10 μm. 1 wt% of hydrophobic silica was externally added to this powder to prepare a black electrophotographic toner.

The prepared toner was placed in a toner cartridge of a copying machine, and an image for evaluation was copied on copy paper. The reflection density of the formed image was about 1.0. The paper was passed through a heat roller at 200 ° C. to break the microcapsules by heat. The papers were further immersed in diethoxyethane to erase the image, and then air-dried. The reflection density of the paper after erasing the image was 0.07, and neither toner flow nor image bleeding was observed. Even after the paper from which the image was erased was allowed to stand at 60 ° C. for 300 hours, there was no change in the reflection density.

Next, a toner was prepared in the same manner as described above except that 10% by weight of styrene / butyl acrylate as a polymer filler was replaced with cholic acid as a decolorizing agent. In the same manner as described above, after an image was formed using the prepared toner, the image was erased. In this case, the reflection density of the paper after erasing the image was 0.05, and the erasing state was better. Even after the paper from which the image was erased was allowed to stand at 60 ° C. for 300 hours, there was no change in the reflection density. Further, when erasing and overwriting were repeated 10 times, an image almost similar to the first image could be obtained.

Example 9 3 parts by weight of GN-169 (manufactured by Yamamoto Kasei) as a coloring compound, 5 parts by weight of phthalic acid as a developer, 1 part by weight of polypropylene wax as a wax component, 90 parts by weight of polystyrene as a binder resin, Charge control agent (LR-14
7) One part by weight was mixed and kneaded sufficiently using a kneader. This kneaded material is pulverized by a pulverizer to have an average particle size of about 10
A μm powder was obtained. Hydrophobic silica 1w for this powder
A blue electrophotographic toner was prepared by external addition of t%.

The prepared toner was placed in a toner cartridge of a copying machine, and a barcode image was copied on copy paper. The reflection density of the formed image was about 0.8. This barcode could be read by a TEC barcode reader. The paper was immersed in a mixed solvent of water / acetone (1: 1) to erase the image, and then air-dried. The reflection density of the paper after erasing the image was 0.10, which was not readable with a barcode reader. This erased state was stable at room temperature, but when the paper was heated to 150 ° C., the reflection density was restored to about 0.7. However, the bar code could not be read by a bar code reader because the image was swollen and deformed and became indistinguishable.

Example 10 Crystal violet lactone (CVL) 3 parts by weight as a coloring compound, gallic acid-D-glucose monoester 2 parts by weight as a developer, polypropylene wax 1 part by weight as a wax component, polystyrene as a binder resin 93 parts by weight, charge control agent (LR-147) 1
Parts by weight were mixed and kneaded sufficiently using a kneader. The kneaded product was pulverized by a pulverizer to obtain a powder having an average particle size of about 10 μm. 1 wt% of hydrophobic silica was externally added to this powder to prepare a blue electrophotographic toner.

The prepared toner was placed in a toner cartridge of a copying machine, and an image for evaluation was copied on copy paper. The reflection density of the formed image was about 0.8. The paper was immersed in a mixed solvent of water / acetone (1: 1) to erase the image, and then air-dried. The reflection density of the paper after erasing the image was about 0.08. This erased state was stable at room temperature, but when the paper was heated to 150 ° C., the reflection density was about 0.7.
Was resurrected until.

Next, a toner was prepared in the same manner as described above except that 5 parts by weight of 93 parts by weight of polystyrene as a binder resin was replaced with 5 parts by weight of cholic acid as a decolorizing agent. In the same manner as described above, after an image was formed using the prepared toner, the image was erased. In this case, the reflection density of the paper after erasing the image was 0.05, and the erasing state was better. Even after the paper from which the image was erased was allowed to stand at 60 ° C. for 300 hours, there was no change in the reflection density. Further, when erasing and overwriting were repeated 10 times, an image almost similar to the first image could be obtained.

Example 11 1 part by weight of crystal violet lactone (CVL) as a color-forming compound and propyl gallate 1 as a color developer
Parts by weight, 10 parts by weight of cholic acid as a decolorizing agent, 5 parts by weight of 1-docosanol and 0.5 parts by weight of 2-octyldecanol as wax components are added to 135 parts by weight of cyclohexane, and sufficiently stirred using a paint shaker. Thus, an oil-based ink was prepared.

This ink was used for stationery parts (I & J FIS
NER Inc. , FV-0200), and an image was drawn by hand on copy paper. The reflection density of this paper was 0.05, and the image could not be visually recognized. This state could be maintained at room temperature for one hour.
When this paper was passed through a heat roller heated to 150 ° C., an image appeared. The reflection density of the image was about 0.9. Next, ethanol was put into the stationery part (FV-0200) and used as an erase pen. After the erase pen was reciprocated about three times on the image, the solvent was dried to erase the image. The reflection density of the paper after erasing was 0.05, and the image could not be visually recognized. Even after the paper was left at 60 ° C. for 300 hours, there was no change in the reflection density. When the paper was passed through the heat roller again, no image appeared.

Example 12 Crystal violet lactone was used as a coloring compound.
Propyl gallate as a color developer and stearyl alcohol as a wax component were mixed at a weight ratio of 1: 1: 1.
20 parts by weight of this mixture and 2-ethyloctanol 1
The parts by weight were added to toluene and dissolved by heating.

A saturated aqueous solution was prepared by dissolving crystal violet lactone and propyl gallate in water until saturated. To 100 g of this saturated aqueous solution, 500 mL of a toluene solution of the image forming material was added and the atmosphere was replaced with nitrogen. The dispersion was cooled to −5 ° C. to form droplets of a frozen image forming material serving as a core material of the microcapsules. 26.5 g of methacrylonitrile was mixed with this dispersion. This dispersion was stirred at a temperature of 0 ° C. or lower for 50 hours to form polymethacrylonitrile around the droplets of the image forming material, thereby preparing colorless microcapsules having an average particle diameter of 0.8 μm. The microcapsules were filtered and dried.

3% by weight of microcapsules were dispersed in 5% by weight gelatin / water solution, and diethylene glycol 0.1% was added.
1 wt% was added to prepare a colorless ink.

This ink was placed in an ink cartridge of an ink jet printer (MJ-510C, manufactured by Epson), and an image was printed on paper. The reflection density of this paper is 0.05
And the image could not be visually recognized. This state could be maintained at room temperature for 100 hours. This paper
When passed through a heat roller set at a temperature of 30 ° C., the image could be developed. The reflection density of the image was about 0.9. The paper was immersed in diethoxyethane to erase the image, and then air-dried. The reflection density of the paper after erasing the image is 0.
07, and the image could not be visually recognized. Even after the paper was left at 60 ° C. for 300 hours, there was no change in the reflection density. When the paper was passed through the heat roller again, no image appeared.

Next, an invisible image was printed on paper in the same manner as described above except that 5 wt% of methyl cholate was added as a decolorizing agent to the ink solution, and the image was developed by passing through a heat roller. The image was erased by immersion in ethane. In this case, the reflection density of the paper was 0.05, and the erased state was better. Even after the paper from which the image was erased was allowed to stand at 60 ° C. for 300 hours, there was no change in the reflection density.

Example 13 2 parts by weight of 3- (4-dimethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide as a color-forming compound After mixing and melting 2 parts by weight of propyl gallate as a coloring agent and 20 parts by weight of β-sitosterol as a reversible decolorizing agent, the mixture was pulverized by a pulverizer to obtain a powder having an average particle diameter of 1 μm. 15 w of the obtained powder in 5 wt% gelatin / water solution
t% was added and microencapsulated by spray drying. 3 wt% of microcapsules were dispersed in a 5 wt% styrene / butyl methacrylate / toluene solution, and 5 wt% of methyl cholate and 0.1 wt% of xylene were added as a decoloring agent to prepare a blue ink.

This ink was placed in an ink cartridge of an ink jet printer (MJ-510C, manufactured by Epson), and an image was printed on paper. The reflection density of the image was 0.45. This paper was passed through a line-type thermal head to be colorless (latent image). The reflection density of the paper was 0.06, and the image could not be visually recognized. When this paper was passed through a heat roller set at a temperature of 130 ° C., an image could be developed. The reflection density of the image was about 0.9. In this embodiment, the latent image formation and development of the image could be repeated several times. This paper was immersed in a mixed solvent of diethoxyethane and ethanol to erase the image, and then air-dried. The reflection density of the paper after erasing the image was 0.05, and the image could not be visually recognized. Even after the paper was left at 60 ° C. for 300 hours, there was no change in the reflection density. When the paper was passed through the heat roller again, no image appeared.

Example 14 20 parts by weight of crystal violet lactone (CVL) as a color-forming compound, 20 parts by weight of propyl gallate as a color developer, and 1-docosanol 10 as a wax component
1 part by weight of glycerin and 1 part by weight of glycerin were mixed and melted to prepare a uniform composition. 40 g of this composition was mixed with 0.5 g of hexamethylene bischloroformate and melted. This mixture was mixed with 5 wt% of gelatin and propyl gallate 1
The solution was dropped into 200 g of an aqueous solution containing wt%, and stirring was continued so as to be fine droplets. 3 g of hexamethylenediamine in 5 parts of water
Stirring was continued at 40 ° C. for 5 hours while gradually dropping the solution dissolved in 0 g into the above aqueous solution. As a result, hexamethylenebischloroformate reacts with hexamethylenediamine at the interface between the microdroplets of the pigment component and water to synthesize an insoluble solid polyurethane, and the pigment component is coated with a polyurethane shell. 1 μm microcapsules formed. The microcapsules were filtered from this suspension and dried.

6 parts by weight of the microcapsules, 1 part by weight of polyethylene wax as a wax component, 82 parts by weight of a styrene / butyl acrylate copolymer (acrylate content: 40 wt%) as a binder resin, and 5 parts by weight of cholic acid as a decolorizing agent , Charge control agent (LR-147)
One part by weight was mixed and kneaded using a kneader. The kneaded product was pulverized with a pulverizer to obtain a powder having an average particle size of 10 μm. 1 wt% of hydrophobic silica was externally added to this powder to prepare a colorless electrophotographic toner.

The prepared toner was placed in a toner cartridge of a copying machine, and an image for evaluation was copied on copy paper. The reflection density of this paper was 0.07, and the image could not be visually recognized. This paper was heated at 190 ° C. 2
The microcapsules were thermally broken through a series of heat rollers to remove glycerin and develop the image. The reflection density of this image was about 1.2. The paper was immersed in diethoxyethane and then dried to erase the image. The reflection density of the paper after erasing was 0.05, and the image could not be visually recognized. Even after the paper was left at 60 ° C. for 300 hours, there was no change in the reflection density. When the paper was passed through the heat roller again, no image appeared.

Example 15 As a color-forming compound, 2-anilino-6- (N-ethyl-
1 part by weight of (N-isobutylamino) -3-methylfluorane, 1 part by weight of propyl gallate as a color developer, and 10 parts by weight of pregnenolone as a reversible decolorant were mixed and melted to prepare a uniform composition. . This composition was pulverized with a pulverizer to obtain a powder having an average particle size of 1 μm. 15 wt% of the obtained powder in a 5 wt% ethylcellulose / ethanol solution
Was added and dispersed, and microencapsulated by spray drying.

6 parts by weight of these microcapsules, 1 part by weight of polyethylene wax as a wax component, 82 parts by weight of a styrene / butyl acrylate copolymer (acrylate content 40 wt%) as a binder resin, 10 parts by weight of cholic acid as a decolorizing agent, Charge control agent (LR-147) 1
Parts by weight were mixed and kneaded using a kneader. The kneaded material was pulverized by a pulverizer to obtain a powder having an average particle diameter of 10 μm. 1 wt% of hydrophobic silica was externally added to this powder to prepare a colorless electrophotographic toner.

The produced toner was placed in a toner cartridge of a copying machine, and an image for evaluation was copied on copy paper. The reflection density of the formed image was 0.37. This paper was passed through a line-type thermal head to be colorless (latent image). The reflection density of the paper was 0.06, and the image could not be visually recognized. When this paper was passed through a heat roller set at a temperature of 190 ° C., an image could be developed. The reflection density of the image was about 0.9. The paper was immersed in diethoxyethane to erase the image, and then air-dried. The reflection density of the paper after erasing the image was 0.05, and the image could not be visually recognized. Even after the paper was left at 60 ° C. for 300 hours, there was no change in the reflection density. When the paper was passed through the heat roller again, no image appeared.

Example 16 1 part by weight of crystal violet lactone (CVL) as a color-forming compound and propyl gallate 1 as a color developer
Parts by weight and 10 parts by weight of pregnenolone as a reversible decolorizing agent were mixed and melted to prepare a uniform composition. This composition was pulverized with a pulverizer to obtain a powder having an average particle size of 1 μm. 5
15 wt% of this powder was added to and dispersed in a wt% gelatin / water solution, and blue microcapsules were obtained by spray drying.

15 parts by weight of the microcapsules, 50 parts by weight of paraffin wax as a wax component, 15 parts by weight of methyl cholate as a decolorizing agent, and ethylene vinyl acetate copolymer (ELVAX 200W, manufactured by DuPont-Mitsui Polychemicals) as a binder resin Parts by weight were mixed and kneaded using a three-roll mill. The obtained kneaded material was applied on a film at a coating amount of about 7 g / m ² using a hot melt coater to produce a blue thermal transfer ink ribbon.

[0204] The ink ribbon is transferred to a bar code printer (TE).
C, B-30) and heat transfer paper (JW-Z10
3) The barcode image was transferred on top. The reflection density of this image was about 0.4. The paper was passed through a line-type thermal head to make the image colorless (latent image). The reflection density of the paper was 0.06, and the barcode was not visible. The paper was passed through a heat roller set at a temperature of 190 ° C. to develop a barcode image. The reflection density of the image was about 0.9. This bar code could be read by a bar code reader (manufactured by TEC, BHT-5075-T). This paper was immersed in diethoxyethane to erase the barcode image and air dried. The reflection density of the paper after erasing was 0.07, and the barcode image could not be visually recognized. Remove the erased paper at 60 ° C for 3
After standing for 00 hours, there was no change in the reflection density.
When the paper was passed through the heat roller again, no image appeared.

Example 17 Crystal violet lactone (CVL), a color-forming compound, was obtained by the in-situ polymerization method in which a monomer was polymerized around a core material using the core material as a catalyst as follows.
And a microcapsule of propyl gallate as a developer were prepared.

A saturated aqueous solution of CVL was prepared. After 100 mL of this aqueous solution was added with 500 mL of hexane, the atmosphere was replaced with nitrogen. This dispersion was cooled to −50 ° C. to form frozen CVL droplets serving as the core material of the microcapsules. 26.5 g of methacrylonitrile monomer was mixed with this dispersion. This dispersion was stirred at a temperature of -30 ° C or lower for 50 hours to form polymethacrylonitrile around the droplets of CVL, thereby preparing microcapsules having an average particle size of 8 µm.

According to the same procedure as described above, the average particle size is 8 μm
Propyl gallate microcapsules were prepared.

5 parts by weight of CVL microcapsules, 4 parts by weight of propyl gallate microcapsules, and 92 parts by weight of a polystyrene oligomer (manufactured by Sanyo Chemical Industries, SB-120) were mixed and kneaded by a twin screw extruder. The kneaded product was pulverized with a pulverizer to obtain a powder having an average particle size of 8 μm.

A solution obtained by dissolving 10% of gelatin in water 300
g, 70 g of the powder obtained above was added, stirred, dried by spray drying, and the surface of the powder was coated with gelatin.

In a solution prepared by dissolving 30 g of a styrene / acrylate copolymer as a polymer filler in 320 g of toluene, 50 g of the powder obtained above, 0.5 g of a charge control agent (Fujikura Kasei, FCA-1001N), Methyl cholate was added as a colorant. The dispersion was dried by spray drying to obtain particles. The obtained particles were classified to obtain a toner having a volume average particle diameter of 10 μm. 1 wt% of hydrophobic silica was externally added to this toner to produce a colorless electrophotographic toner. This toner and a ferrite carrier (F-150, manufactured by Nippon Iron Powder Co., Ltd.) were mixed at a toner concentration of 4% to prepare a two-component developer.

This toner was placed in a toner cartridge of a copying machine (manufactured by Toshiba, Leo Dry BD-8510), and an image was copied on paper. In this copying machine, the surface temperature of the fixing roller is set to about 200 ° C., and the surface temperature of the pressure roller is set to about 160 ° C. The toner transferred onto the paper is colorless and transparent until it reaches the fixing device. When the paper conveyed in the copier is caught between the fixing roller and the pressure roller, heat is applied from above and below the paper to melt the resin in the toner, and at the same time the toner is pressed and the microcapsule wall is pressed. Is broken. As a result, the coloring compound and the developer, which are the core material of the microcapsules, flow out and diffuse into the molten binder resin, and the color is developed by the interaction between them. Thereafter, the molten binder resin is cooled and fixed on the paper.

Thus, a blue-colored image was obtained.
The reflection density of the image was as high as 1.2 or more, and there was no fog. Copying was performed on 100,000 sheets of paper, but no toner contamination was observed in the copying machine.

The paper on which the image was formed was immersed in a mixed solvent of 2-butanone / ethyl alcohol (1: 1) to erase the image and air-dried. The reflection density of the paper after erasing the image is 0.0
6, and no toner flow or image bleeding was observed. Even after the paper from which the image was erased was allowed to stand at 60 ° C. for 300 hours, there was no change in the reflection density.

Example 18 The image forming material of the present invention can be used for maintaining information security. Here, the facsimile system shown in FIG. 11 will be described as an example. This system includes an inkjet output facsimile apparatus 100, a heating type image developing apparatus 200, and a solvent immersion type image erasing apparatus 300.
It consists of.

[0215] The facsimile apparatus 100 is
1, first and second inkjet devices 102, 10
3 and a drive unit 104 for driving these inkjet devices. The first ink jet device 102 is loaded with erasable ink of normal coloring type. The second inkjet device 103 is usually loaded with a colorless erasable ink.

When electronic information transmitted from the outside is received, paper is fed from the paper feeding device 101. The electronic information includes ordinary information and confidential information that can be distinguished from each other, and the drive unit 104 has a circuit for identifying the information. Ordinary information such as an address is recorded on paper by the first ink jet device 102 loaded with the erasable ink of the normal coloring type. This ordinary information is visible on paper. On the other hand, the confidential information is recorded on the paper by the second inkjet device 103 loaded with the normally colorless erasable ink. This confidential information is held on the output paper as a latent image that cannot be viewed.

The heating type image developing apparatus 200 has a heat roller 201 and an opposing roller 202 and is portable. The developing temperature is set to a temperature equal to or higher than the temperature at which the microcapsules are destroyed by heating and pressurizing, and sufficiently lower than the temperature at which the image forming material loses color. The recipient who has received the output paper passes the output paper through the image developing device 200. As a result, the microcapsules normally contained in the colorless erasable ink are destroyed by heating and pressurizing, and the latent image is developed and becomes visible.

The image erasing device 300 includes a solvent immersion tank 301.
And a heat roller 302 and an opposing roller 303. A polar organic solvent is used as the erasing solvent. The temperature of the heat roller 302 is set to be equal to or higher than the erasing temperature of the erasable ink. The recipient who has read the confidential information passes unnecessary paper through the image erasing device 300. The paper is immersed in a solvent, dried and then heated back to white paper.

Since no information appears on this blank sheet again through the heating type developing device, it can be reused (reused) by the facsimile machine.

In this embodiment, an image is formed by an ink jet method, but electrophotography or thermal transfer may be used. The development method is performed by heating, but may be pressure development or solvent development. Further, although the erasing method is performed by immersion in a solvent, heating erasing may be performed as long as a good erasing state is obtained.

[0221]

As described above, when the image forming material of the present invention is used, a clear image can be formed, and a good erased state can be obtained by heat or solvent treatment. Further, when another image forming material of the present invention is used, not only complete erasure but also writing and erasing of an image can be performed repeatedly. Then, the paper after the image erasure can be reused, and the paper resources can be used effectively.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating toner particles according to the present invention.

FIG. 2 is a sectional view showing toner particles according to the present invention.

FIG. 3 is a cross-sectional view illustrating toner particles according to the present invention.

FIG. 4 is a cross-sectional view illustrating toner particles according to the present invention.

FIG. 5 is a sectional view showing a thermal transfer ink ribbon according to the present invention.

FIG. 6 is a cross-sectional view showing a thermal transfer ink ribbon according to the present invention.

FIG. 7 is a cross-sectional view showing the toner particles according to the present invention.

FIG. 8 is a sectional view showing toner particles according to the present invention.

FIG. 9 is a cross-sectional view illustrating the toner particles according to the present invention.

FIG. 10 is a sectional view showing an erasing pen and a writing / erasing pen used in the present invention.

FIG. 11 is a schematic configuration diagram of a facsimile system using the image forming material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Base film 12 ... Back coat film 13 ... Ink film 51 ... Pen body 52 ... Erasing solution 53 ... Erasable ink 54a, 54b, 54c, 54d ... Felt 55a, 55b ... Cap 100 ... Facsimile machine 101 ... Paper feeder 102, 103 Inkjet device 104 Drive unit 200 Image developing device 201 Heat roller 202 Opposing roller 300 Image erasing device 301 Solvent immersion tank 302 Heat roller 303 Opposite roller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 101/00 C09D 11/02 C09D 11/00 11/16 11/02 B41M 5/26 D 11/16 J G03G 9/08 365 (72) Inventor Kenji Sano 1st, Komukai Toshiba-cho, Yuki-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba R & D Center (72) Inventor Koichi Tsukomi 1 Kozuka-Toshiba-cho, Yuki-ku, Kawasaki-shi, Kanagawa Address Toshiba Research and Development Center Co., Ltd. BA71 4J002 AB00X AE05X BC01W BG01W BG03W BG07W BG13W CG00W CH07W CH09W CL00W CN01W CN03W DH026 EE036 EF016 EF066 EH026 EH116 EJ016 EV236 FB286 FD01W FD096 GQ00 4J039 AB01 AB12 AD03 AD06 AD08 AD09 AD10 AD11 AD12 AD13 AD14 AE06 AE10 AE13 BA19 BA28 BB00 BC06 BC07 BC16 BC19 BC20 BC27 BC29 BC31 BC50 BC54 BC56 BC65 BC69 BC73 BC74 BC75 BC77 BD03 BE12 CA11 EA29 GA06 GA10 GA24 GA27 GA28

Claims (10)

[Claims] Claims: 1. A color former, a developer, a matrix agent in which the total number of electron donating groups is 5% or less of the total number of carbon atoms, and a decolorant; An erasable image forming material, wherein the developer and the decoloring agent are separated by microcapsules. 2. A color former, a developer, a matrix agent having a total number of electron-donating groups of 5% or less of the total number of carbon atoms, a decolorant, and a glass transition point or a softening point of the matrix agent. Contains a polymer filler higher than 20 ° C., and the color former and the developer, and the polymer filler,
An erasable image forming material characterized by phase separation or co-dispersion. 3. A polymer filler is externally added to a core containing a color former, a color developer, and a matrix having a total number of electron-donating groups of 5% or less of the total number of carbon atoms. ,
An erasable image forming material, characterized in that at least one of the core and the polymer filler contains a decoloring agent. 4. The erasable image forming material according to claim 1, wherein the color developer has a carboxyl group or a sugar skeleton. 5. It contains a coloring agent, a developer, a decoloring agent, a matrix agent having a total number of electron-donating groups of 5% or less of the total number of carbon atoms, and an organic solvent having a boiling point of 150 ° C. or more. A decolorizable image forming material characterized by the following. 6. A microcapsule containing a color former, a developer, and an organic solvent having an electron donating group,
A decolorizable image-forming material comprising a decoloring agent and a matrix agent having a total number of electron-donating groups of 5% or less of the total number of carbon atoms. 7. A microcapsule containing a color-forming compound, a microcapsule containing a color developer, a matrix agent having a total number of electron-donating groups of 5% or less of the total carbon number, and a decoloring agent. A decolorizable image forming material comprising: 8. A color developing compound, a color developer, a reversible decoloring agent, a compatible decoloring agent or a phase separation inhibitor, and the total number of electron donating groups is 5% or less of the total number of carbon atoms. An erasable image-forming material comprising a matrix agent. 9. A colorless image is formed on an image recording medium by using the image forming material according to claim 5, and is contacted with a first heating condition, a first pressurizing condition, or a first solvent. An image recording and erasing method, wherein the color of the image forming material is developed by the following method, and the image forming material is decolored by the second heating condition, the second pressurizing condition, or the contact of the second solvent. 10. A color-formed image is formed on an image recording medium using the image forming material according to claim 8, and the image forming material is contacted by a first heating condition, a first pressurizing condition, or a first solvent. And the image forming material is colored by the second heating condition, the second pressing condition, or the contact with the second solvent, and the third heating condition, the third pressing condition, or the third heating condition.
An image recording and erasing method, wherein the image forming material is decolorized by contact with the solvent.