JPH06122194A - Ink jet recording method - Google Patents

Abstract

PURPOSE:To record an image of high image quality on a recording medium by preventing a repelling phenomenon and diffusion wetting by irradiating the ink image formed on a transfer medium with light before transferring the same to the recording medium under pressure. CONSTITUTION:A transfer drum 1 is rotated by a drive means 6. Ink droplets are selectively emitted from a plurality of the nozzles of a recording head 2 receiving the supply of ink from an ink tank 21 to record an ink image on the transfer drum 1. The transfer drum 1 having the ink image supported thereon is rotated to be irradiated with light by a light irradiation device. Thereafter, the ink image reaches the contact part with a backup roller 3 and recording paper 5 is sent into the contact part by a recording paper feed means to be brought into contact with the transfer drum 1 and pressure is applied to the recording paper to transfer the ink image on the transfer drum 1 to the recording paper 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording method in which an ink image is formed on a transfer medium and then transferred to the recording medium to obtain an ink image on the recording medium.

[0002]

2. Description of the Related Art A transfer type ink jet printer is characterized in that it does not cause ink jet clogging caused by unintentional contact between recording paper or paper dust and a recording head, and high reliability is obtained. As such a transfer type inkjet printer, the configurations described in US Pat. No. 4,538,156 and US Pat. No. 5,099,256 are known.

In these apparatuses, an ink jet recording head (hereinafter referred to as a recording head) having a plurality of nozzles is provided on a cylindrical transfer medium with a gap therebetween. The recording step includes a writing step of writing an ink image on a transfer medium and a transfer step of transferring an ink image onto the recording sheet by bringing a recording sheet, which is a recording medium, into contact with the transfer medium and pressing from behind. There is.

[0004]

In these apparatuses, it is necessary to perform high-efficiency transfer without transfer residue at a low pressure. That is, since the transfer of the ink image from the transfer medium to the recording paper is performed by applying pressure, the transfer medium needs to be a material that easily separates the ink image, that is, a material having a low surface energy. On the other hand, the ink image is formed on the transfer medium by dots formed by the ink droplets ejected from the recording head. On materials with low surface energy,
The dots have a property of being spherically gathered due to surface tension. Therefore, a plurality of dots are likely to aggregate on the transfer medium to form a large dot. As a result, dots are formed at positions displaced from the initial positions, or the ink image formed by the aggregate of dots is deformed. This phenomenon will be described below as a cissing phenomenon.

FIG. 9 shows the shape of an image actually formed when a straight line is printed with a dot group. Figure 9 at the beginning
A plurality of dots are printed at regular intervals at the print position 901 shown in (a). However, on the transfer medium, various ink images are actually formed as shown in FIGS. 9B to 9F depending on the difference in surface energy and the surface state. (B)
Is a case where the position where the ink is printed becomes an image as it is, which is actually difficult unless it is absorbed by the transfer medium.

FIGS. 9C and 9D show typical examples of the cissing phenomenon in the case of printing ink on a material having a low surface energy. Ink breakage 902 due to ink moving or flowing on the transfer medium due to the cissing phenomenon
Or the ink reservoir 903 is formed. In this case, the actual characters and images are of low quality. That is, it lacks smoothness, the part that should be continuous is interrupted, and it looks bad,
It becomes hard to read. Since the surface tension of water is large, the cissing phenomenon is remarkable in the ink containing water as a main component.

If a transfer medium having a high surface energy is used to prevent this, (1) the ink image is hard to be separated from the transfer medium, and therefore the ink remains on the transfer medium after the transfer. That is, the transfer efficiency is low.

(2) When an ink of a material that easily wets a transfer medium having a high surface energy is used, the ink on the transfer medium spreads largely due to a phenomenon called diffusion wetting, and an accurate ink image cannot be formed. .

The typical ink image behavior of diffusion wetting is shown in FIG.
It shows in (f). In the diffusion wet state, not only the dot group arranged on a straight line as in (f) becomes thick but also a pattern of data which is not actually continuous is connected and cannot be accurately formed as intended. .

FIG. 3E shows a case where dots are connected to each other only from the position where ink is printed and neither flicker nor diffusion and wetting occur, which is preferable for forming characters and images. However, it is actually easy to peel from the transfer medium and
It is difficult to achieve this state, and if good peeling from the transfer medium is assumed, a transfer medium with low surface energy will be used, and the cissing phenomenon shown in FIGS. (C) and (d) will occur.

On the other hand, the liquid has a property of easily permeating in the fiber direction on the recording paper. The resulting smearing of ink on the recording paper also reduces the image quality on the recording paper. As for bleeding, as described in JP-A-62-92849, before transfer from a transfer medium to a recording paper, the ink on the transfer medium is heated to evaporate the ink solvent to increase the viscosity or solidify. There is also known a method of transferring to a recording sheet. Known heating methods include a method of blowing high-temperature air onto the ink image on the transfer medium, and a method of incorporating a heater inside the transfer medium to heat the transfer medium itself.

According to an experiment conducted by the present inventor, by heating an ink image on a transfer medium to increase its viscosity, cissing phenomenon of a transfer medium having a low surface energy and diffusion wetting phenomenon of a transfer medium having a high surface energy are prevented. be able to. Therefore, in addition to preventing bleeding on the recording paper, a transfer medium with low surface energy is used to form a high quality ink image without cissing phenomenon on it, achieving high transfer efficiency and good load under low load. Can be transcribed.

However, in this case, there is a problem that it is necessary to constantly supply energy in order to keep the transfer medium at a high temperature. Further, there is a problem that a step of raising the temperature of the transfer medium is required before the operation. In particular, in order to prevent the cissing phenomenon and diffusion wetting, it is necessary to rapidly increase the viscosity of the ink on the transfer medium, and it is necessary to maintain the transfer medium at a high temperature at which the solvent is instantly evaporated. That is, in the case of an ink containing water as a main solvent component, it is necessary to keep the transfer medium at a temperature that accelerates evaporation of water or a temperature at which a curing reaction of the ink occurs in order to quickly increase the viscosity of the ink. This is because the temperature of the transfer medium surrounding rises, especially the ink in the recording head that faces through a minute gap becomes more viscous and solidifies, clogging the nozzle,
This has caused a problem that a stable ejection operation cannot be performed.

From the above viewpoint, the present invention is intended to obtain a high quality ink image on a transfer medium which is capable of low pressure transfer and has a high peeling property, while preventing the image quality from being deteriorated due to the cissing phenomenon. The purpose is to obtain high quality recording by low pressure transfer. Furthermore, it is to realize the above characteristics without increasing the temperature of the transfer medium and its peripheral members.

[0015]

According to an ink jet recording method of the present invention, an ink jet recording is performed in which an ink image is written by a recording head which faces a transfer medium via a gap and which scans the transfer medium, and transfers the ink image to the recording medium. A method comprising: a. Step of forming an ink image on a transfer medium by selectively ejecting ink droplets from a recording head b. A step of irradiating the ink image on the transfer medium with light having a higher absorptivity to ink than the absorptivity to the transfer medium c. A step of bringing the transfer medium and the recording medium into contact with each other, applying pressure, and transferring the ink image on the transfer medium to the recording medium.

Further, desirably, the transfer medium is an elastic layer having a low light absorbing property, which is formed on a metallic glossy surface having a light reflecting property.

[0017]

According to the above method, since the ink on the transfer medium absorbs the irradiation light and the solvent evaporates rapidly to increase the viscosity, cissing phenomenon, diffusion wetting and bleeding phenomenon are prevented, and the ink on the recording medium is prevented. High quality recording can be obtained. At this time, since the transfer medium does not generate heat, the temperature of the transfer medium itself and surrounding members does not rise.

[0018]

EXAMPLES The ink jet recording method of the present invention will be described below with reference to examples.

The ink jet printer of the first embodiment is shown in a perspective view in FIG. 1 and an AB sectional view in FIG. An inkjet recording head 2, a light irradiation device 4, and a backup roller 3 that is a transfer unit are sequentially arranged around a transfer drum 1 that is a transfer medium.

The recording head 2 is an ink jet recording head of a type that pressurizes ink by using a piezoelectric element and ejects the ink from nozzles, and has a plurality of nozzles which are spaced apart from each other in the axial direction of the transfer drum 1 by a certain distance. ing.

The transfer drum 1 has a fluorosilicone rubber (for example, as a transfer medium) around an aluminum tube 11.
The elastic layer 12 made of FE-251 manufactured by Shin-Etsu Chemical Co., Ltd. is laminated. Fluorosilicone rubber has a white color and high light reflectivity. The blank tube 11 has a metallic luster surface on the outer periphery. The elastic layer 12 preferably has a property of easily peeling the ink image.

The backup roller 3 is a metal roller made of aluminum and is configured to be pressed against the transfer drum 1 by a load device (not shown). In the transfer step, the transfer drum 1 is pressed via the recording paper 5. The transfer load is about 10 kg in this embodiment.

The ink is obtained by dispersing a pigment together with an emulsion in pure water which is an ink solvent together with an additive such as a surfactant. Specifically, 3% by weight of carbon black as a pigment, 8% by weight of styrene-acrylic copolymer emulsion as an emulsion, 8% by weight of glycerin as a moisturizing agent, 6% by weight of polyvinylpyrrolidone as a water-soluble resin, 1% by weight of a surfactant, and a preservative. An ink prepared by appropriately adding a few wt% of the above was used.

The light irradiator 4 has a lamp 41 which is a rod-shaped halogen lamp, has a reflector 42, collects the light energy of the lamp 41 on the transfer drum 1, and irradiates it onto the elastic layer 12 of the transfer drum 1. Irradiate.

Next, the operation will be described.

The rotation direction and movement direction of each member are indicated by arrows in the figure.

The transfer drum 1 is rotated by the driving means 6. Ink droplets are selectively ejected from a plurality of nozzles of the recording head 2 to which ink is supplied from the ink container 21, and an ink image is recorded on the transfer drum 1. The transfer drum 1 carrying the ink image moves along with the rotation and is irradiated with light by the light irradiation device 4.

After that, the recording paper 5 reaches the contacting portion with the backup roller 3, and the recording paper 5 is sent to this contacting portion by a recording paper conveying means (not shown) to contact with the transfer drum 1 to apply pressure, , The ink image on the transfer drum 1 is transferred to the recording paper 5.

In the apparatus of this embodiment, the light energy including the infrared rays emitted from the lamp 41 is condensed by the reflection plate 42 to irradiate the ink image 43 on the elastic layer 12, as shown in FIG. In the experiments conducted by the present inventors using the ink having the above-mentioned composition and the elastic layer, the temperature of the ink on the elastic layer 12 was rapidly increased by the light irradiation, and the viscosity of the ink on the elastic layer 12 was increased. That is, when the light irradiation is not performed, the cissing phenomenon is remarkably low in the ink image, but the cissing phenomenon is suppressed by the light irradiation, and accurate dots can be formed on the elastic layer 12 to obtain a high quality image. I was able to. On the other hand, the irradiation light 44 directly irradiates the elastic layer 12 in the portion that does not carry the ink image. Since the elastic layer 12 is smooth, a part thereof is reflected on the surface. A part reaches the inside of the elastic layer 12. Further, the light that has passed through the elastic layer 12 reaches the outer circumference of the elementary tube 11,
It is reflected by the metallic glossy surface of the raw tube 11, passes through the elastic layer 12 again, and diffuses to the outside. Since the light absorption of the elastic layer is low,
The temperature rise of the elastic layer 12 is small. Further, since the elastic layer 12 has a low thermal conductivity, there is no heat inflow from the ink image. Therefore, the temperature rise of the elastic layer 12 was not recognized. For this reason, the heat generation of the raw tube 11 was also not recognized. Therefore, only the ink image is selectively heated by the light emission energy of the lamp 41 and the temperature of the member around the transfer drum is not increased. Further, since the elastic layer 12 has a low thermal conductivity, heat is not transferred to the elastic layer 12 and the raw tube 11 by heating the ink image. Therefore, the ink image is rapidly heated by the light irradiation. Therefore, it is possible to prevent the repelling phenomenon and the movement and deformation of the ink dots due to the wetting of the diffusion, and to obtain an accurate and high-quality ink image on the elastic layer 12. For the same reason, the ink image can be efficiently heated with a small input energy.

Therefore, as in this embodiment, a high-quality ink image can be obtained with the ink containing water as a main component on the elastic layer 12 having high releasability, and high-quality and high-efficiency transfer can be realized at a low pressure. High quality recording can be performed on recording paper.

Similar to the first embodiment, as the elastic body having small light absorption and high releasability, fluorosilicone and silicone rubber (for example, TSE manufactured by Toshiba Silicone Co., Ltd. are used.
221) can also be used. The same effect was obtained by using an infrared heater lamp instead of the rod-shaped halogen lamp used in the first embodiment.

A second embodiment of the present invention is shown in a perspective view of FIG. 4 and FIG.
It is shown in the AB cross section. In the apparatus of this embodiment, a polyethylene terephthalate (PET) layer 12 is used as a transfer medium.
To use. The apparatus is configured such that the backup roller 3 can contact and release the transfer drum 1 by the contact control device 31. The ink image is formed on the transfer drum 1 by the recording head 2 mounted on the carriage 22 and moving in the axial direction of the transfer drum 1 to scan. That is, the transfer drum 1 is stopped during the scanning operation, and recording is performed in a predetermined band-shaped area in the axial direction of the transfer drum 1. With the backup roller 3 in the released state, after forming an ink image for one page on the transfer drum 1, the backup roller 3 is brought into contact with the recording paper 5 and the ink image on the transfer drum 1 is transferred to the recording paper 5. It is configured to be transferred to. The light irradiation device 4 is
It is configured to be mounted on the carriage 22 together with the recording head 2 and to heat an ink image formed by ink dots ejected from the recording head 2 that moves in the axial direction immediately after the ejection. As the lamp 41, a small halogen lamp is used. The transfer drum 1 is configured by laminating a PET layer 12 (Diafoil # 300 manufactured by Diafoil Co., Ltd.) on an aluminum tube 11. Since polyethylene terephthalate has high transparency and does not absorb light, only the ink image can be efficiently heated.

The other structure and operation are the same as those of the first embodiment, and the description thereof will be omitted.

FIG. 6 shows a third embodiment. In this embodiment, glass is used as the transfer medium. Only the transfer drum 1 is shown in the figure. The transfer drum 1 is composed of a cylindrical transfer glass 12. Since glass is highly transparent and does not absorb light, part of the irradiation light is reflected by the surface of the portion that does not carry an ink image, and the remaining light that reaches the inside diffuses to the outside without being absorbed inside. Therefore, only the ink image can be efficiently heated. Furthermore, since the strength can be increased, it is not necessary to form a multilayer structure with the raw tube.

The other structure and operation are the same as those of the first and second embodiments, and the description thereof will be omitted.

Here, the radiation characteristics of the lamp and the transfer medium used in the present invention will be described. In the graphs of FIGS. 7 and 8, the horizontal axis represents the wavelength of light and the vertical direction represents the radiant absorption rate of energy. The right side of the horizontal axis of the graph makes a large contribution to heating in the near infrared region. FIG. 7 is a graph showing the radiation characteristics at each wavelength of the halogen lamp used in this example. FIG. 8 is a graph showing the light absorption characteristics of ink and various transfer media at each wavelength. The absorption characteristics of the elastic layer 12 of the first embodiment are rubber B in the drawing, the absorption characteristics of the PET layer 12 of the second embodiment are resin D in the drawing, and the absorption characteristics of the transfer glass 12 of the third embodiment are glass in the drawing. Shown. While the ink shown in FIG. 8 absorbs a lot of energy with respect to the lamp that emits light having the characteristics shown in FIG. 7, the transfer medium is rubber B, rubber C, resin D.
Or, when glass is selected, it is found that it is difficult to absorb energy. On the other hand, if a black material such as rubber A having a high light absorptivity is used for the transfer medium, the energy of the ink is close to the energy absorptivity of the ink. Therefore, as in the embodiment of the present invention, it is preferable that the transfer medium is made of a material which is as transparent or white as possible and which hardly absorbs light, and the surface of which is smooth so as not to impair the light reflectivity.

[0037]

According to the present invention, the ink image formed on the transfer medium is irradiated with light by the light irradiation device and then pressure-transferred onto the recording medium. Since the ink on the transfer medium absorbs the irradiation light and the solvent evaporates to rapidly increase the viscosity, the cissing phenomenon and the diffusion wetting can be prevented, and high quality recording can be obtained on the recording medium. Further, there is no bleeding phenomenon on the recording paper at the time of transfer, and the image is faithfully transferred onto the recording medium. At this time, since it is not necessary to keep the transfer medium at a high temperature and heat is not generated, adverse effects such as a decrease in reliability due to the high temperature of the transfer medium itself and surrounding members do not occur. Therefore, there is an effect that a high-quality ink image can be obtained by preventing deterioration of image quality due to a cissing phenomenon on a transfer medium which is capable of low-pressure transfer and has high releasability.

On the other hand, with regard to the ejection characteristics from the recording head, it is possible to realize more stable characteristics when the ink has a low viscosity. On the other hand, the image quality of the recording is low due to phenomena peculiar to the low-viscosity liquid such as cissing phenomenon, bleeding phenomenon and diffusion wetting. On the contrary, in the method of the present invention, it is possible to suppress the image deterioration peculiar to the low-viscosity liquid, and it becomes possible to perform high-quality recording using the low-viscosity liquid ink. It also has the effect of being obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of an ink jet printer showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the inkjet printer showing the first embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view of the ink jet printer showing the first embodiment of the present invention.

FIG. 4 is a perspective view of an ink jet printer showing a second embodiment of the present invention.

FIG. 5 is a sectional view of an ink jet printer showing a second embodiment of the present invention.

FIG. 6 is a perspective view of an ink jet printer showing a third embodiment of the present invention.

FIG. 7 is a diagram showing an example of spectral energy distribution of a lamp used in the inkjet recording method of the present invention.

FIG. 8 is a diagram showing an example of spectral energy absorption rates of various transfer media used in the inkjet recording method of the present invention.

FIG. 9 is a diagram illustrating ink image deterioration due to a cissing phenomenon on a transfer medium.

[Explanation of symbols]

 1: Transfer drum (transfer medium) 2: Recording head 3: Backup roller (transfer means) 4: Light irradiation device 5: Recording paper (recording medium) 6: Driving means 11: Element tube 12: Elastic layer, PET layer, transfer Glass (transfer medium) 21: Ink tank 22: Carriage 23: Head drive means 31: Contact control device 41: Lamp 42: Reflector 43: Ink image 44: Irradiation light 901: Printing position 902: Ink interruption 903: Ink reservoir

Claims (2)

[Claims] 1. A transfer medium is faced with a gap,
An inkjet recording method of writing an ink image with a recording head that scans the transfer medium and transferring the ink image onto the recording medium, comprising: a. Step of forming an ink image on a transfer medium by selectively ejecting ink droplets from a recording head b. A step of irradiating the ink image on the transfer medium with light having a higher absorptivity to ink than the absorptivity to the transfer medium c. An ink jet recording method comprising a step of bringing a transfer medium and a recording medium into contact with each other and applying a pressure to transfer the ink image on the transfer medium to the recording medium. 2. The ink jet recording method according to claim 1, wherein the transfer medium is an elastic layer having low light absorption formed on a metallic glossy surface having light reflectivity.