JPH0425538B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention applies electrophotographic technology to one-time exposure,
The present invention relates to image-forming particles used in an image-forming method for obtaining a color copy through one-time development. Specifically, the present invention relates to light-transparent image-forming particles that have the function of optically separating colors and the function of developing color. More specifically, the present invention relates to light-transparent image forming particles containing a colorant for color separation and a sublimable color former for color development.

Structure of the conventional example and its problems The image forming particles according to the present invention are, for example,
-49307, can be used in the image forming method disclosed in Japanese Patent Publication No. 56-785. The principle of image formation is as follows. First, imaging particles are electrostatically deposited in a layer onto a photoconductive photoreceptor. After image exposure, particles through which light has passed, that is, particles whose electrostatic attraction with the photoreceptor has weakened or ceased to act, are removed from the photoreceptor to form a particle image. Next, the particle image and an image receptor containing a sublimable color former developer are brought into close contact with each other and heated. Then, the sublimable color former in the particles sublimates and reacts with the color developer of the image receptor to develop color. Finally, the particles on the image receptor are removed to obtain a colored image using a sublimable color former.

Next, in order to clarify the subject matter of the present invention, a one-shot color recording method will be described in which the above-described image forming principle is applied to obtain a full-color image by one exposure and one development.

There are three types of image forming particles: image forming particles B that transmit blue-violet light and develop a yellow color, image forming particles G that transmit green light and develop a magenta color, and image forming particles R that transmit red light and develop a cyan color. Use mixed particles. First, as shown in FIG. 1, three types of image forming particles R, G, and B are electrostatically deposited in a single layer on the surface of a charged photoconductive photoreceptor 1. The photoconductive photoreceptor 1 has a photoconductive layer 3 mainly composed of a photoconductor such as zinc oxide or amorphous silicon on a conductive substrate 2 such as an aluminum plate. Next, as shown in Figure 2, for example, red, green,
A light image of a color original 4 consisting of blue-violet and white is exposed. Charges under the particles through which the light of the optical image selectively passes through exposure are photo-attenuated and lose their electrostatic adhesion. Next, as shown in FIG. 3, the photoreceptor 1 is vibrated using, for example, an electromagnetic vibrator 5, to cause particles that have lost their electrostatic adhesion to fall off, thereby obtaining a color-separated particle image of the color document.

Next, after electrostatically transferring the particle image on the photoreceptor 1 to the image receptor 6, the heating roller 7 is moved as shown in FIG.
heat the particles. Then, the sublimable color former in the particles sublimes and reacts with the color developer 8 of the image receptor 6 to develop color. Incidentally, the image receptor 9 is a base paper 6 on which a color developer is supported.

To explain this color development, for example, in the area exposed to red light, only G and B particles remain. Therefore, when these particles are heated together with an image receptor, the area under particle G develops magenta color, and the area below particle B develops yellow color. Furthermore, the sublimable color former reproduces red color by appropriately mixing colors through sublimation and diffusion. In this way other green, blue-purple,
The parts exposed to each white light can also reproduce the colors of a color original. After color development by heating, the particles on the image receptor 6 are removed to obtain a color copy.

Conventionally, various types of image forming particles of this type have been proposed. For example, in Japanese Patent Publication No. 56-2342, the surface of colored transparent particles made by dyeing a transparent resin such as melamine resin with a colorant is coated with a sublimable color former mixed with a transparent binder such as styrene resin. There is. Another example of the structure is one in which a colored pigment and a sublimable color former are finely dispersed in a transparent binder such as polyvinyl alcohol and then granulated. Furthermore, in Tokuko No. 56-776, Tokuko No. 56-776
Image-forming particles whose surfaces are coated with a conductive agent such as copper iodide have been proposed as disclosed in Japanese Patent No. 2342-2342.

However, when these conventionally proposed particles contain a sublimable color former, the light transmittance is reduced by 20 to 30% compared to particles that do not contain the color former. Therefore, there was a problem that the exposure time became long. When the cause of this was investigated in detail, it was found that the sublimable color former supported on the particles was crystallized, which caused the particles to devitrify like frosted glass. Further, when conventional particles are exposed to a high temperature atmosphere of 40 to 60° C. for a long period of time, the sublimable color former gradually sublimates, resulting in a decrease in the color density of copies. Furthermore, when the particles are subjected to conductive treatment, the surface resistance of the particles tends to vary widely, which causes the problem that the image quality of copies is difficult to maintain.

OBJECTS OF THE INVENTION It is an object of the present invention to overcome the conventional problems as described above and to provide image-forming particles with excellent light transmittance.

Structure of the Invention Image-forming particles according to the present invention are composed of a sublimable color former that develops color by reacting with a color developer, that is, an electron-accepting substance, and particles that can transmit light, and the sublimable color former is compatible with a resin. It is characterized by being amorphous.

Description of Examples The sublimable color former used in the present invention is colorless or pale in powder form under normal conditions, and is difficult to sublimate. Once heated, it quickly sublimates, and is combined with a color developer such as activated clay, polyparaphenylphenol, 4,
It is desirable to use a material that develops a high concentration of color when it reacts with an electron-accepting substance such as 4'-diphenylpropane.
Representative examples of sublimable color formers having the above characteristics are described below.

The sublimation color former, which produces a yellow color, has
N-(1,2-dimethyl-3-yl)methylidene-2,4-dimethoxyaniline, N-(1-methyl-2-phenylindol-3-yl)methylidene-2,4-dimethoxyaniline, etc. .

The sublimable color former that develops magenta includes 7'-diethylamino-1,3,3-trimethyl-5-chloroindolinobenzospiropyran,
7'-(N-methyl-N-phenyl)amino-1,
Examples include 3,3-trimethylindolinobenzospiropyran and 7'-diethylamino-1,3,3,5-tetramethyl-indolinobenzospiropyran.

Sublimation color former that produces cyan color has
Examples include 3,7-bis-diethylamino-10-trichloroacetyl-phenoxazine, 3,7-bis-diethylamino-10-isobutyryl-phenoxazine, and 3,7-bis-diethylamino-10-acetyl-phenoxazine.

Generally, sublimable color formers that can be applied to the present invention are often oil-based crystals. If such a crystalline sublimable color former is supported on image forming particles in its crystal form, light incident on the particles will be diffusely reflected, resulting in a significant decrease in the light transmittance of the particles. Therefore, in order to prevent this, it is desirable to make the sublimable color former amorphous and support it on the particles. The sublimable color former can be made amorphous by dissolving or melt-mixing it in a compatible resin. A colorless and transparent resin is suitable for this purpose. Representative examples are shown below. For example, ethyl cellulose, acetyl cellulose, acrylic resin, polymethyl methacrylate, styrene resin, polyvinyl acetate, etc. can be used. The mixing ratio of the sublimable color former and the above-mentioned resin varies depending on the molecular extinction coefficient of the sublimable color former used, but is preferably 1 to 30 parts by weight of the resin per 100 parts by weight of the sublimable color former. A sublimable color former made amorphous by such a method is almost colorless and transparent, and does not prevent sublimation of the sublimable color former when heated.

Next, the structure of the image forming particles according to the present invention will be explained based on the drawings. 5 to 7 show examples thereof.

Particles 10 in FIG. 5 are made by dispersing and mixing a coloring agent such as a dye or pigment and microscopic particles of an amorphous sublimable color former in a colorless and transparent resin binder such as a styrene-butadiene copolymer or an acrylic resin. It is granulated by

Particles 11 shown in FIG. 6 are particles intended to prevent spontaneous sublimation of a sublimable color former in a high-temperature atmosphere of 40 to 60°C, and the surfaces of particles 10 shown in FIG. It is coated with an anti-sublimation protective agent 12 whose main component is a water-based resin such as aminated styrene which is colorless and transparent and has a softening point of 60° C. or higher. These aqueous resins hardly transmit the sublimable color former gas at temperatures below 60°C, but have a property that the gas permeation becomes markedly improved under color development conditions of, for example, 150°C or higher, and are extremely effective in the present invention. Further, the blocking resistance of the anti-sublimation protective agent can be improved by mixing inorganic fine powder such as silicon oxide or barium sulfate into the aqueous resin.

The particles 13 shown in FIG. 7 have the same basic structure as the particles shown in FIG. 5, and differ only in the form of the amorphous sublimable color former. That is, microscopic bodies 14 of amorphous sublimable color former are microencapsulated with the sublimation-preventing protective agent 15 described in FIG. 6 as a wall material.

In the particles 16 shown in FIG. 8, the surface of colored transparent particles 17 such as colored glass beads or colored resin beads is coated with a coloring material 18 in which an amorphous sublimable color former is dispersed in an anti-sublimation protective agent. It is something. The shape of the image forming particles described above is preferably spherical, and the particle size is suitably from several microns to 50 microns.

Generally, in order to facilitate electrostatic adhesion of image-forming particles onto a photoconductive photoreceptor in a single layer and precisely, it is desirable that the particles have a surface resistance of 10 ⁶ Ω·cm or less and conductivity. To impart conductivity to the particles, conductive agents such as copper iodide, tin oxide, or polymeric quaternary ammonium salts are supported on the surface or inside of the particles using a conventional method. obtain.

The coloring agent for imparting a color separation function to the image forming particles is preferably one having excellent spectral performance and hot pressing performance. Representative examples are shown below.

As a red colorant, CI acid red 6.1
4, 18, 27, 42, 82, 83, 85, 8
7,133,211, CI Pigment Orange 1
3, 24, 2115, CI Pigment Red 5,
22, 112, 114, etc.

As a green colorant, CI Acid Green 9,2
7, 40, 43, CI pigment green 37,
Group 38 and CI Pigment Yellow 12, 13, 1
There are combinations with the 4, 100, and 109 groups.

As a blue colorant, CI Solbend Blue 4
8, 49, CI Acid Blue 23, 40, 62,
83, 120, CI Pigment Blue 1, CI Pigment Violet 1, 3, etc.

These colorants may be used alone or in combination of two or more, if necessary.

The present invention will be explained below with reference to Examples.

Example 1 Cyan sublimable color former 3,7-bis-diethylamino-10-trichloroacetyl-
When 100 parts by weight of phenoxazine and 10 parts by weight of ethyl cellulose, which is an amorphous resin, were dissolved and mixed in methylene chloride, the mixture was dried and solidified. A) was obtained.

Next, a dispersion liquid having the following formulation was granulated by a spray drying method to obtain spherical particles.

Red colorant: CI Pigment Red 5 1.0 parts by weight CI Pigment Orange 2115 2.0 Binder: SBR emulsion 38 parts by weight Heat resistant agent: Colloidal silica 30 parts by weight Fine powder of coloring material A (coloring material A was mixed with an average of 1 part by weight in a jet mill) Milron (fine powder): 2.2 parts by weight Dispersed material: Anionic activator 0.4 parts by weight Water: 52 parts by weight The obtained particles were classified into 10 to 20 microns to obtain image forming particles with red and cyan coloring. Ta. On the other hand, a zinc oxide photoreceptor was charged in a dark place, the particles were sprinkled on it, and the excess particles were wiped off, so that the particles were arranged in a substantially single layer on the surface of the photoreceptor. The particle filling rate at this time was 60%. After irradiating this with a light image of a color original for 2 seconds, when the photoreceptor is vibrated with the side on which the particles are attached facing down, it corresponds to a particle image that has been color-separated in red, that is, a part of the color original that does not contain red. An image was obtained in which particles remained as they were on the photoreceptor in the areas where the particles were removed, and particles were removed in areas corresponding to areas containing red.

This is then layered with bottom paper (clay paper) for pressure-sensitive copying, whose main component is activated clay, as an image receptor.
When the particles are removed by heating at 200° C. for 4 seconds, an image is obtained in which only the portions of the image receptor where the particles were attached are colored in clear cyan. The color density of the printed area was 1.1, and the density of the non-printed area was 0.12.

For comparison, an image was formed using image forming particles granulated according to the same recipe as above without making the sublimable color former amorphous, and the exposure time was 2.6 seconds.

Example 2 Color forming material A fine powder of Example 1 100 parts by weight Anti-sublimation protective agent: Bullulan 50〃 Water: 200〃 The mixture according to the above formulation was sufficiently dispersed using Ballmin, and color forming material A was prepared using pullulan by spray drying.
A microencapsulated material (hereinafter referred to as "coloring material B") was obtained.

Next, the particles were granulated using the same recipe as in Example 1 to obtain image forming particles. Place the particles in a 50℃ oven for 24 hours.
After leaving it for a while, an image was formed in the same manner as in Example 1. The exposure time was 2 seconds and the color density of the image area was
It was 1.0.

For comparison, a similar experiment was conducted using the image forming particles of Example 1, and the color density of the image area was 0.7.

Example 3 The image-forming particles obtained in Example 1 were subjected to conductive treatment using a fluid coating method using a 2 weight percent copper iodide solution in acetonitrile until the particle surface resistance became 10 ³ Ω·cm.

Next, when an image was formed using the image forming particles in the same manner as in Example 1, the particle filling rate in the particle layering step was 70%, the exposure time was 2 seconds, and the color density of the image area was 1.3. The density of the non-printing area was 0.10.

Example 4 Green colorant: Spirit Blue #1 (manufactured by Yamamoto Kagakusei Co., Ltd.) 4 parts by weight Spiron Yellow NB-1 (manufactured by Hodogaya Chemical Co., Ltd.) 6 Binder: Epoxy resin (Dainippon Ink Co., Ltd.) “Epicron H” manufactured by Kagaku Kogyo Co., Ltd.
-157) 80 parts by weight Curing agent: Butylated melamine resin (Supervecamine J-840, manufactured by Dainippon Ink and Chemicals Co., Ltd.) 20 parts by weight Solvent: Methyl cellosolve 100 parts by weight The mixture of the above formulation was spray-dried. As a result, spherical green light transmitting particles were obtained.

Next, a mixture according to the following formulation was dissolved and mixed, and then dried and solidified to obtain a colorless and transparent solid (hereinafter referred to as "color forming material C") in which the sublimable color former was made amorphous.

Magenta sublimable color former: 7'-diethylamino-,1,3,3-trimethyl-5-chloroindolinobenzospiropyran
100 parts by weight Resin for amorphization: Styrene resin 6 Next, when a dispersion liquid with the following formulation was spray-dried, a green spectral magenta color was formed in which the surface of the green light-transmitting particles was coated with a sublimable color former made amorphous. Image-forming particles were obtained.

Green light transmitting particles: 100 parts by weight Coloring material C 4 Anti-sublimation protective agent: Aminated nylon 40 Next, using these image forming particles, an image was formed in the same manner as in Example 1, with an exposure time of 2 seconds, A clear magenta image with a color density of 1.3 in the printed area and 0.12 in the non-printed area was obtained.

In addition, the image-forming particles were placed in a 50°C oven for 24 hours.
After leaving it for a while, an image was formed in the same manner as above, and the color density of the image area was 1.2.

Effects of the Invention As explained above, in the image forming particles of the present invention, the sublimable color former is compatible with the resin and becomes amorphous, so the light transmittance of the particles is improved and the exposure time can be shortened. be. Furthermore, since the light transmittance of the particles is improved, the amount of signal light that passes through the particles is increased, which has the effect of improving the color purity of the image. In addition, since the sublimable color former is made amorphous, it is possible to use a sublimation-preventing protective agent with almost no effect on the light transmittance of the particles, which improves the storage stability of the particles in high-temperature atmospheres of 40 to 60 degrees Celsius. This has the effect of significantly improving

[Brief explanation of drawings]

1 to 4 show an example of a color image forming method using the image forming particles of the present invention. FIGS. 5 to 8 show structural examples of the image forming particles of the present invention. 1... Photoconductive photoreceptor, 2... Conductive substrate, 3
... Photoconductive layer, 4 ... Color original, 5 ... Electromagnetic vibrator, 6 Image receptor, 7 ... Heating roller, 8 ... Color developer, 9 ... Base paper, 10, 11, 13, 16 ……
Image forming particles, 12,15... anti-sublimation protective agent,
14... Sublimable color former microscopic body, 17...
...Colored transparent particles, 18...Coloring material.

Claims (1)

[Scope of Claims] 1. Particles transparent to light that are not fixed to an image forming member and include a coloring agent and a sublimable color former that develops color by reacting with a color developer, wherein the sublimable color former is ethyl cellulose, It is made amorphous by dissolving and mixing with a resin selected from the group of acetyl cellulose, acrylic resin, polymethyl methacrylate, styrene resin, and polyvinyl acetate, and is coated with an aqueous resin. image-forming particles. 2. The image forming particles according to claim 1, wherein the aqueous resin is polyvinyl alcohol, pullulan, aminated nylon, or aminated styrene. 3. The image forming particles according to claim 1 or 2, wherein at least the particle surface is conductive and the particle resistance is 10 ⁶ Ω·cm.