JPH0415939B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention applies electrophotographic technology to make one exposure
This paper relates to improvements to image-receiving sheets that are particularly useful in one-shot color image forming methods that obtain color images through redevelopment.Specifically, this paper is concerned with improvements to image-receiving sheets that are particularly useful in one-shot color image forming methods that obtain color images through redevelopment. Light-transparent particles containing a colorless heat-sublimable dye that reacts and develops color are electrostatically attached to the light, and after image exposure, the particles whose electrostatic attraction has been weakened or removed are mechanically or electrically attached.
The particles are removed from the photoreceptor to obtain a particle image, and the particle image is electrostatically transferred to a receptor sheet containing an electron-accepting substance, and heated to react and color the colorless thermosublimable dye contained in the particles. The present invention relates to improving the coloring properties of a receiving sheet in which a colored image is obtained by removing particles from the receiving sheet. Conventional electrophotography generally utilizes a photoconductive substance to form an electrical latent image on a photoreceptor by various means, and then develops the latent image using a colored toner (or, if necessary, on paper, etc.). After transferring the powder image to ),
It was fixed by heating or solvent vapor. However, with this method, since the toner is colored, there is a problem of contamination during manufacturing and handling during developing operations.The toner is a fine powder and easily flies up during manufacturing, contaminating hands, feet, and clothes, and when used. When replenishing toner, toner would fly up and contaminate the surrounding area. Furthermore, it is extremely difficult to obtain colored transparent images using conventional methods, and image forming methods have been proposed that solve the above-mentioned drawbacks (for example, Japanese Patent Laid-Open No. 149123/1983). This image forming method uses colorless and transparent light-transmitting particles, which are image-forming particles, on the surface of a support containing a photoconductive substance to have red, green, and blue spectral functions. By electrostatically adhering a mixture of particles containing a colorless heat-sublimable dye that develops a yellow color, and then irradiating a light image onto the surface of the support, the surface of the support below the light-transmitting particles is The charge is photoattenuated to form a latent image. The latent image obtained here is a force pattern obtained by converting the optical signal from the original into a signal of the strength of electrostatic attraction acting on the support and the particles. Therefore, by applying an external force to this system to weaken the electrostatic attraction with the support or removing the removed particles from the support, a particle image can be obtained, and the particle image is transferred to a receiving sheet. After transferring it to a paper, it is heated and colored, and used particles are removed to obtain a color print. The colorless sublimable dye used herein is colorless or pale yellow and is substantially colorless, and examples of the dye that develops yellow include Michler's ketone and a reduced form of auramine, such as bis(4-dimethylaminophenyl)-methoxyethane. - Leuco dyes such as N-bis(4-dimethylaminophenyl)-methyl-N-ethylaniline or Schiff base compounds described in JP-A-54-140539, such as N-[4-(N-methyl-
N-benzylamino)benzylidene]-aniline,
N-[4-(N-methyl-N-benzylamino)benzylidene]-4-methoxyaniline, and the like. Examples of magenta coloring agents include phenazine dyes such as 2-amino-7-dimethylphenazine, fluoran dyes such as 3-dialkylaminobenzofluorane, and spirobenzopyran indole compounds described in JP-A-54-28140. , 4-
(1,3,3-trimethyl-indolino)methyl-7-(N-methyl-N-phenyl)amino-1',
3′,3′-trimethyl-spiro[2H-1-benzopyran-2,2′-[2′H]-indole], 4-(1,
3,3,5-tetramethyl-indolino)methyl-7-(N-methyl-N-phenyl)amino-1',
Examples include 3',3',5'-tetramethyl-spiro[2H-1-benzopyran-2,2'-[2'H]-indole]. Examples of cyan coloring agents include stilbene dyes such as bis(4,4'-dialkylaminodiphenyl)ethylene, N-bis(4-dialkylaminophenyl)-methyl-β-hydroxyethylaniline, and JP-A-53 Acylleucophenoxazine compounds described in No.-42733, e.g. 3,7-
Bis-diethylamino-10-dichloroacetyl-
Examples include phenoxazine and 3,7-bis-diethylamino-10-isobutyryl-phenoxazine.
Electron-accepting substances are effective for coloring these colorless heat-sublimable dyes. The structure of this receptor sheet may include only a coloring layer containing an electron-accepting substance, but the surface resistance is usually difficult to increase sufficiently, and the transfer efficiency in electrostatic transfer tends to be insufficient. Therefore, products that have a structure in which a colorless and transparent layer with high surface resistance, which allows the sublimable dye gas to easily permeate and does not inhibit color development, are often used (Japanese Patent Application Laid-Open No. 16143/1983). desired. The color-forming layer is a layer of an electron-accepting substance and an adhesive, and may also contain calcium carbonate, silicon oxide, etc. for color-forming and other reasons.As a binder, a material with strong binding power and little thermal yellowing is recommended. Desirably, for example, a styrene-butadiene copolymer, acrylic resin, or polyvinyl acetate resin layer is preferable. Further, it is preferable that the applied coloring layer is subjected to calender treatment in order to make the surface resistance uniform. The dielectric layer is preferably made of a releasing agent to prevent used particles from binding after coloring in the heating/coloring layer, white inorganic fine powder and a binder to facilitate the permeation of the sublimed gas of the colorless sublimation dye. This layer has a surface resistance of 10 ¹² Ω·cm or more to improve particle transfer efficiency. However, various other configurations are possible. As the release agent, a transparent or white material with high resistance is desirable, and polyethylene or silicone resin is typically preferred. In particular, emulsions of these materials are preferred because of their excellent compatibility with binders. The white inorganic fine powder is preferably silicon oxide, which is effective as a coloring aid. The binder is preferably one that has high resistance and is transparent, has good binding properties with the coloring layer, and has strong folding strength, such as styrene-butadiene copolymer, acrylic resin, polyvinyl acetate, etc. . In particular, emulsions of these resins are preferred because they have excellent air permeability. Electron-accepting substances are effective for coloring the colorless heat-sublimable dyes, and conventionally, activated clays, inorganic substances such as zeolites, bisphenol A,
Phenolic substances such as salicylic acid derivatives, P-phenylphenol, and their resins have been known. However, when inorganic materials such as activated clay are colored with sublimable dyes, 150%
Heating for 1 to 30 seconds at a temperature of -220°C was necessary, and this heat caused the problem that the base paper changed color to a yellowish color. Also, because it is an inorganic material, the paper was lackluster and the colored areas lacked luster, resulting in dull images that lacked sharpness. When using a phenolic substance such as bisphenol A, there is relatively little discoloration due to heat, but the drawback is that the coloring ability is basically weak, and it also softens due to heat, causing particles to form during transfer. It has the disadvantage that it comes into contact with the receiving sheet and contaminates the printed image. As a result of intensive studies to improve the above-mentioned drawbacks, the inventors of the present invention discovered that JP-A No. 57-1989-1 has been developed as an electron-accepting substance.
A clay mineral obtained by acid-treating the clay mineral described in No. 15996 and having a layered structure consisting of tetrahedral silica so that the SiO ₂ content becomes 82 to 96.5% by weight on a dry basis (drying at 105°C for 3 hours). in an aqueous medium with a compound of magnesium and/or aluminum which is at least partially soluble in said medium and, if this soluble compound is other than a hydroxide, an alkali or acid such that a hydroxide is formed. Using a semi-synthetic solid acid (hereinafter simply referred to as semi-synthetic solid acid) produced by neutralizing with water, introducing magnesium and/or aluminum components into the acid-treated clay mineral, and optionally drying. The inventors have discovered that the above-mentioned drawbacks can be improved by using the method, that there is no discoloration during heating, there is no adhesion of particles, and that clear images with gloss and high density can be obtained in the colored image areas, leading to the present invention. Various materials can be used as the support of the present invention, such as paper, plastic film, nonwoven fabric, metal plate, etc. From the viewpoint of transfer efficiency in electrostatic transfer, the sheet-like support is required to be electrically conductive and is treated with electrical conductivity. Preferably. Note that a layer of conductive material may be provided on the back surface of the base paper if necessary. Hereinafter, this will be explained in more detail with reference to Examples.
All parts represent parts by weight. Example 1 The sensitizing dye Rose Bengal was used as a photoconductive substance.
Tartrazine and Diamond Green GWA
approximately 350 to 700 mμ using zinc oxide sensitized with
A panchromatic photosensitive plate was prepared. Next, three types of solutions, red, green, and blue, were prepared according to the following formulations. (1) Red solution water-soluble melamine resin 100 parts (weight parts, same below) Hardening agent 10 parts Rose Bengal 2 parts Methyl orange 2 parts Water 100 parts (2) Green solution water-soluble melamine resin 100 parts Hardening agent 2 parts Patent paint P-Blue (Sumitomo Mikuni Chemical Co., Ltd.)
0.5 parts Leveling Yellow (manufactured by Sumitomo Chemical Co., Ltd.) 2 parts Kayasion Green (manufactured by Nippon Kayaku Co., Ltd.) 2 parts water 100 parts (3) Blue solution Water-soluble melamine resin 100 parts Hardening agent 10 parts Spirit Blue (manufactured by Yamamoto Kagakusei Co., Ltd.) 3 parts Rose Bengal 2 parts Acid Violet (manufactured by Kanto Chemical Co., Ltd.) 1 part Water 100 parts Sumitekus M-3 is also used as a hardening agent by the company.
EPX was used. Spray-dry the above three solutions separately to obtain particles with a particle size of 20
Red, green, and blue colored transparent particles of ~40 μm were obtained, and using these, light-transmissive colored particles were produced by a two-fluid method using the following blending ratios. (1) Red light transmitting particles Red colored particles 100 parts Colorless sublimable dye that develops cyan color (3,7-bisdiethylamino-10-dichloroacetyl-phenoxazine) 5 parts Polyamide resin 3 parts Water 100 parts (2) ) Green light-transmitting coloring particles Green colored particles 100 parts Colorless sublimable dye that develops magenta color [4-(1,
3,3-trimethyl-indolinomethyl-7-
(N-methyl-N-phenyl)amino-1',3',
3'-trimethyl-spiro [2H-1-benzopyran-2,2'-[2'H]-indole] 3 parts polyamide resin 3 parts water 100 parts (3) Blue light-transparent coloring particles Blue colored particles 100 parts Yellow Colorless sublimable dye bis(4-
(dimethylaminophenyl) 7 parts methoxyethane polyamide resin 3 parts water 100 parts The above polyamide resin used was Arafix 200 manufactured by Arakawa Chemical Co., Ltd. On the other hand, as a receiving sheet (1) Color forming layer liquid semi-synthetic solid acid (manufactured by Mizusawa Chemical Co., Ltd.) 100 parts Calcium carbonate 30 parts Colloidal silica 20 parts Styrene-butadiene copolymer latex 15 parts Water 150 parts The above materials were mixed by stirring. A coloring layer solution was obtained. (2) Dielectric layer liquid Low molecular weight polyethylene emulsion 50 parts Colloidal silica 40 parts Styrene-butadiene copolymer latex 25 parts The above materials were stirred and mixed to obtain a dielectric layer liquid. Next, the coloring layer liquid of (1) was applied at a rate of 7 g/m ² (weight after drying, hereinafter the same) to 70 g/m ² high-quality paper treated with polymeric quaternary ammonium salt, and calendered. After that, 3 g/m ² of the dielectric layer liquid (2) was applied onto the coloring layer and calendered to obtain a receiving sheet. Next, the photosensitive plate was charged by corona charge, and a mixture of the three types in equal amounts was sprinkled thereon as light-transmitting coloring particles containing a colorless sublimable dye. At this time, since the particles were conductive, they were packed in a line on the photosensitive plate closest to each other. Next, color pattern exposure was performed, and the photosensitive plate was vibrated with an electromagnetic vibrator for development, and then the entire surface was exposed to electrostatically transfer the particles onto the above-mentioned receiving sheet. Furthermore, in order to obtain a colored image, heat development was carried out for 5 seconds on a hot plate heated to 220°C. When the used particles were then removed with a fur brush, there was no yellowing of the background, and a clear image with high gloss and high density was obtained in the colored image area. Comparative Example 1 The results of the same experiment using conventional activated clay (manufactured by Mizusawa Chemical Co., Ltd.) in place of the semi-synthetic solid acid in the coloring layer solution of Example 1 are shown in Table 1 along with the results of Example 1. show.

[Table] As shown in Table 1, the image forming sheet of the present invention had very clear images with little yellowing and high density with gloss in the colored areas.

Claims (1)

[Claims] 1. In a receiving sheet in which a colorless sublimable dye is colored by providing a coloring layer containing an electron-accepting substance on a conductive support and further layering a colorless, transparent, and air-permeable dielectric layer, as the electron-accepting substance, A clay mineral with a layered structure consisting of silica tetrahedrons has a SiO ₂ content of 82 to 82 on a dry basis (drying at 105°C for 3 hours).
A clay mineral obtained by acid treatment to a concentration of 96.5% by weight is brought into contact in an aqueous medium with a compound of magnesium and/or aluminum which is at least partially soluble in said medium, and if this soluble compound is other than a hydroxide. introducing magnesium and or aluminum components into the acid-treated clay mineral by neutralization with alkali or acid so that hydroxides are formed;
A receiving sheet for image formation, characterized in that it uses a semi-synthetic solid acid produced by drying if desired.