JPS62109063A - Printing original plate for electrophotoengraving - Google Patents

Abstract

PURPOSE:To permit easy photoengraving with high sensitivity and high printing resistance by providing an electric charge generating layer on a conductive base and providing an electric charge transfer layer which contains an electric charge transfer material and PVA silylated by a silylating agent or reactant of the silylated PVA and crosslinking agent and of which the surface can be made hydrophilic thereon. CONSTITUTION:The coating liquid prepd. by adding the electric charge generating material into an org. solvent contg. a binder resin, for example, polyester resin, polyvinylidene chloride resin, etc. according to need and uniformly dispersing the soln. by a dispersing means such as ball mill is coated on the conductive base 1 and is dried to form the charge generating layer 2. The soln. prepd. by dissolving the electric charge transfer material and the silylated PVA in an org. solvent is coated on the charge generating 2 and is dried to form the charge transfer layer 3 which can be made hydrophilic. The coating liquid prepd. by adding the crosslinking agent such as polyisocyanate compd. is coated on the charge transfer layer 2 and is dried and is further subjected to a crosslinking reaction by executing a heat treatment to form the charge generating layer 3 which can be made hydrophilic in the case of using the crosslinking agent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a printing original plate for electrophotographic engraving, and more particularly to a printing original plate whose surface is made hydrophilic after forming a toner image by electrophotography.

[Prior Art] As a planographic printing original plate, those using a photosensitive resin or a silver halide photosensitive material are known.

However, lithographic printing original plates using photosensitive resin have high printing durability, but have low sensitivity and cannot be used for so-called direct plate-making.Therefore, during plate-making, it is necessary to create a negative or positive from the original using a silver halide film. Therefore, it requires large-scale equipment and has drawbacks such as the time required for plate making. Further, although printing original plates using diffusion transfer development or hardening development methods of silver halide photosensitive materials can be directly plate-made, they have the drawbacks of low printing durability and high cost per sheet.

As printing original plates for direct plate making using electrophotography, for example, Japanese Patent Publication Nos. 47-47610 and 48-
No. 40002, Special Publication No. 4g-18325, Special Publication No. 18325, Special Publication No. 18325
Zinc oxide-resin dispersion systems are known as described in publications such as No. 15766 and Japanese Patent Publication No. 51-25761. After forming a toner image on this printing original plate by electrophotography, it is treated with an acidic aqueous solution containing, for example, a ferrocyan salt in order to make the non-image area hydrophilic. Printing plates made in this way suffer from peeling due to mechanical pressure applied during printing and penetration of dampening water into the photosensitive layer and conductive treatment layer, destroying the hydrophilic layer on the surface. The force is about s, ooo to to, ooo pieces.

Further, although zinc oxide-resin dispersion printing original plates are dye-sensitized to have sensitivity in the visible light region, they still do not exhibit sensitivity sufficient for practical use in the long wavelength light region of 600 nm or more. Therefore, low-power and inexpensive He-Ne
The disadvantage is that exposure cannot be performed using a laser or semiconductor laser.

On the other hand, Special Publication No. 37-17162, Special Publication No. 38-775
No. 8, Special Publication No. 46-39405, Japanese Patent Publication No. 52-243
No. 7, JP-A-55-153948, JP-A-55-10
No. 5254, JP-A-56-107246, JP-A-56
-16125, JP-A No. 57-147656, JP-A-56-146145, and JP-A-57-161863, for example, describe the use of hydrophilic conductive materials such as grained aluminum plates. A layer consisting of an organic leading compound and an alkali-soluble resin on a support, a layer in which a charge-generating pigment such as a phthalocyanine pigment is dispersed in an alkali-soluble resin, or an electron-withdrawing substance or an electron-donating substance is added to this dispersed layer. In addition, a printing original plate for electrophotographic engraving that is provided with a sensitized layer is described. This type of printing original plate is made by forming a toner image on the photosensitive layer using an electrophotographic method, and then eluting and removing the photosensitive layer in the non-image area with an alkaline solution.It is a printing plate with high printing durability using direct platemaking. Although it has the advantage of being able to obtain
It has the disadvantage that a high output light source must be used.

Furthermore, Japanese Patent Publication No. 5606/1989 describes a method for producing a printing original plate of a hydrophilic treatment type on the surface of a non-image area, which is easy to make by providing a specific resin layer on an ordinary electrophotographic photoreceptor. That is, a printing original plate is disclosed in which an electrophotographic photosensitive layer 1- is provided with a surface layer made of a vinyl ether-maleic anhydride copolymer and a hydrophobic resin compatible therewith. This layer is a layer that can be made hydrophilic by treating the non-image area with an alkali to open the acid anhydride ring portion with water after the toner image is formed.

However, the vinyl ether-maleic anhydride copolymer used here becomes water-soluble when the acid anhydride ring portion is ring-opened and made hydrophilic, so that high printing durability cannot be obtained. If the proportion of hydrophobic resin in the layer is increased in order to improve water resistance, the hydrophilicity of the surface will decrease, causing background stains on printed matter, so it has been difficult to achieve both hydrophilicity and water resistance.

[Purpose] The purpose of the present invention is to solve the above-mentioned problems of conventional printing plates for electrophotolithography, and to provide printing plates that are particularly sensitive, have high printing durability, and are easy to plate-make. .

[Structure] The printing original plate for electrophotographic engraving of the present invention is provided with a charge generation layer containing a charge generation substance on a conductive support, and on top of which is a charge generation layer containing a charge transport substance and a polyvinyl alcohol silylated with a silylation agent. Alternatively, it is characterized in that a charge transport layer containing a reaction product of the silylated polyvinyl alcohol and a crosslinking agent and whose surface can be made hydrophilic is provided.

Here, a typical example of the above-mentioned "silylated polyvinyl alcohol" is trimethylsilylated polyvinyl alcohol, and a typical example of the "crosslinking agent" is a polyisocyanate compound.

Hereinafter, the present invention will be explained in more detail based on the accompanying drawings.

FIG. 1 is a sectional view showing the basic structure of the printing original plate according to the present invention, in which 1 represents a conductive support, 2 represents a charge generation layer, and 3 represents a charge transport layer whose surface can be made hydrophilic.

As mentioned above, the charge generation layer 2 contains a charge generation substance, and in the image forming process by electrophotography, the charge generation substance absorbs light in the areas irradiated with light during image exposure after charging. electrons and holes are generated. Due to the electric field, electrons and holes flow, one into the conductive support 1 and the other into the charge transport layer 3, through which they neutralize the surface charge and form an electrostatic latent image.

At this time, the surface of the layer 3 that holds the electrostatic latent image needs to be highly resistive and hydrophobic to the extent that the charge does not diffuse in the surface direction (if it is hydrophilic, the surface will become static due to the adsorption of water). (The latent image cannot be retained).

The electrostatic latent image is then developed with toner charged to the opposite polarity to the surface charge and fused to form a toner image on layer 3. Since printing is performed based on the difference between the lipophilicity of the thus formed toner image (t31 ink property) and the hydrophilicity of the non-image area, the surface of layer 3 needs to be hydrophilic during printing.

In this way, the layer 3 is required to have the function of changing from hydrophobicity during electrostatic latent image formation to hydrophilicity during printing, in addition to transporting charges. The silylated polyvinyl alcohol or the reaction product of the silylated polyvinyl alcohol and the crosslinking agent used in layer 3 in the present invention is hydrophobic in nature and has sufficient resistance to retain the electrostatic latent image. However, when treated with an acidic or alkaline aqueous solution, the silyl ether group is hydrolyzed and returns to its original hydroxyl group, making it hydrophilic and enabling printing. Moreover, although it is hydrophilic, it is not water-soluble and has sufficient water resistance, so that high printing durability can be obtained.

Examples of the charge generating substance used in the charge generating layer 2 of the present invention include zinc oxide, titanium oxide, zinc sulfide, selenium,
Examples include inorganic compounds such as selenium alloys, cadmium sulfide, cadmium selenide, and silicon, and organic compounds as shown in (1) to (14) below.

(1) Triphenylmethane pigments such as malachite green and crystal violet; methylene blue,
Thiazine dyes such as methylene green; Astrazone dyes such as Astrazone Orange R, Astrazone Yellow 3GL, and Antoanthros 6B; Cyanine dyes such as Eisen Astrafuroxin FF; Xanthine dyes such as Rhodamine B; 2,6-diphenyl-4-( N, N-
Cationic dyes such as pyrylium dyes such as dimethylaminophenyl) thiapyrylium verchlorate, benzopyrylium salts.

(2) Perylene pigments such as perylene anhydride and perylene imide.

(3) Indigo pigment.

(4) Quinacridone pigment.

(5) Polycyclic quinones such as anthraquinones, pyrenequinones, anthoanthros, and flavanthrones.

(6) Bisbenzimidazole pigment.

(7) Square methine pigment.

(8) Indathlon pigment.

(9) Phthalocyanine pigments such as metal phthalocyanines such as copper phthalocyanine and metal-free phthalocyanines.

(10) A charge transfer complex consisting of an electron-donating substance such as poly-N-vinylcarbazole and an electron-accepting substance such as 2,4,7-trinitrofluorenone.

(11) Pyrylium salt dye and polycarbonate -
A eutectic complex formed from resin.

(12) Barbyric acid derivative or thiobarbital acid derivative.

(13) Azo pigments such as monoazo pigments, disazo pigments and triazo pigments. Examples of monoazo pigments include monoazo pigments with central skeletons such as anthraquinone and N-phenylcarbazole, and examples of disazo pigments include benzidine pigments such as Diane Blue and Chlordiane Blue, or N-ethylcarbazole, stilbene, and disazo pigments. Stilbenzene, naphthalene, fluorenone.

Fluorene, anthraquinone, 2,5-diphenyl-1
, 3,4-oxadiazole, dibenzothiophene, dibenzothiophene dioxide, acridone, phenanthrenequinone, etc., and trisazo pigments include, for example, triphenylamine or N-phenylcarbazole as the central skeleton. There are trisazo pigments, etc.

The silylated polyvinyl alcohol used in the hydrophilizable charge transport layer 3 can be obtained by reacting polyvinyl alcohol with a silylating agent in an organic solvent. As the silylating agent, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, t-butyldimethyldichlorosilane, dimethylchlorosilane,
Halosilanes such as diphenyldichlorosilane, triphenylchlorosilane, triethylfluorosilane, 1-limethylbromosilane; hexamethyldisilazane, N,
Sylyamines such as N-dimethylaminotrimethylsilane, N,N-diethylaminotrimethylsilane, dimethylsilyldimethylamine, dimethylsilyldiethylamine, heptamethyldisilazane, nanomethyltrisilazane, and tetramethyldisilazane; bis(trimethylsilyl)
Acetamide, bis(dimethylsilyl)acetamide,
N-methyl-N-trimethylsilylacetamide, bis(trimethylsilyl)trifluoroacetamide, N-
Silylamides such as methyl-N-trimethylsilylacetamide, N-trimethylsilylacetamide, trimethylsilyldiphenylurea, bistrimethylsilylurea; trimethyltrifluoromethylsulfonate, N-
Trimethylsilylpiperidine, N-trimethylsilylimidazole, 1-phenyl-4-1-ramethylsilyl-
5-tetrazolinone, trimethylacetoxysilane, etc. can be used.

Among these, if a hydrophilic layer is formed with trimethylsilylated polyvinyl alcohol obtained using a trimethylsilylating agent such as trimethylchlorosilane, hexamethyldisilazane, or bis(trimethylsilyl)acetamide, hydration during hydrophilization is particularly effective. It has the advantage of being able to be decomposed quickly.

The silylation of polyvinyl alcohol is carried out using the silylating agent mentioned above, for example, using Bradereck+.
5trunk, H, Menrad, Die Mak
romolekulareChemie 126.13
9 (1969) or JP-A-55-164614, organic solvents that do not react with the silylating agent, such as N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, dioxane,
It can be easily synthesized by reacting in the presence of 1 to toluene, pyridine, triethylamine, etc., or directly reacting without using a solvent.

The saponification degree of the raw material polyvinyl alcohol is 98.
Either ~100 pill % fully saponified polyvinyl alcohol or 70-98 mole % partially saponified polyvinyl alcohol can be used. In addition, in this silylation reaction,
From the relationship between the hydrophobicity and water resistance of the layer, 5 of the hydroxyl groups contained
It is desirable to silylate 0% or more. If it is less than this, the water resistance of the layer will not be sufficient and the printing durability will also be low. In addition, when reacting with a crosslinking agent, it is recommended to limit the silylation reaction to about 95% of the hydroxyl groups in order to react the hydroxyl groups remaining without being silylated in the silylated polyvinyl alcohol with the crosslinking agent. preferable. If the silylation is 95% or more, crosslinking will not be sufficiently performed and good printing durability will not be obtained.

A typical example of the crosslinking agent is a polyisocyanate compound. Polyisocyanate compounds include toluene-2,4-diisocyanate 1-, toluene-2,6
-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate 1-, triphenylmethane-4,4',
4"-I ~ aromatic polyisocyanates such as tris(p-incyanate phenyl) thiophosphite, polymethylene polyphenyl isocyanate, xylylene diisocyanate, or aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, or These include dimers and trimers.

An example of producing silylated polyvinyl alcohol is as follows.

(Production example) Polyvinyl alcohol (Poval 217 manufactured by Kuraray Co., Ltd.: degree of saponification 87 to 89 mol%, average degree of polymerization 1700) 4.4
Part by weight was heated and dissolved in 170 parts by weight of N,N-dimethylformamide, and after cooling to room temperature, 12 parts by weight of 1-ethylamine and 13 parts by weight of trimethylchlorosilane were dissolved.
Parts by weight were added and reacted at room temperature for 3.5 hours to obtain 9.6 parts by weight of 1-trimethylsilylated polyvinyl alcohol.

The infrared absorption spectrum of this product was as shown in FIG.

The charge transport layer 3 contains a charge transport substance.

Charge transporting substances include hole transporting substances and electron transporting substances, and examples of hole transporting substances include 2,5-bis(4-diethylaminophenyl)-1,3°4-oxadiazole, 2,5- Bis(4-(4-diethylaminostyryl)
phenyl)-1,3゜4-oxadiazole, 2-(9
-Oxadiazole compounds such as ethylcarbazolyl-3-3-5-(4-diethylaminophenyl)-1,3,4-oxadiazole; 2-vinyl-4-(2-chlorophenyl)-5- Oxazole compounds such as (4-diethylamino)oxazole, 2-(4-diethylaminophenyl)-4-phenyloxazole; l-phenyl-3-(4-diethylaminostyryl)-5-(4-
diethylaminophenyl)pyrazoline, 1-phenyl-
Pyrazoline compounds such as 3-(4-dimethylaminostyryl)-5-(4-dimethylaminophenyl)pyrazoline; 2゜2'-dimethyl-4,4'-bis(diethylamino)triphenylmethane, 1,1-bis Diphenylmethane compounds such as (4-dibenzylaminophenyl)propane and tris(4-diethylaminophenyl)methane; 9-(4-dimethylaminobenzylidene)fluorene, 3-(9-fluorenonedene)-9-ethylcarbazolene compounds; 9- (4-diethylaminostyryl)
Styryl anthracene compounds such as anthracene, 9-bromo-10-(4-diethylaminostyryl) anthracene; 1,2-bis(4-diethylaminostyryl)
Benzene, 1,2-bis(2.

Distyrylbenzene compounds such as 4-dimethoxystyryl)benzene; 9-ethylcarbazole-3-aldehyde 1-methyl-1-phenylhydrazone, 9-ethylcarbazole-3-aldehyde 1-benzyl-1-phenylhydrazone, 4-diethylamino Benzaldehyde 1
．． 1-diphenylhydrazone, 2,4-dimethoxybenzaldehyde 1-benzyl-1-phenylhydrazone,
4-diphenylaminobenzaldehyde 1-methyl-1
- Hydrazone compounds such as phenylhydrazone; Stilbene compounds such as 4-diphenylaminostilbene, 4-dibenzylaminostilbene, 4-ditolyl aminostilbene: l-(4-diphenylaminostyryl)naphthalene, 1-(4-dibenzyl) Styrylnaphthalene compounds such as (aminostyryl) naphthalene; α-phenylstilbene compounds such as 4'-diphenylamino-α-phenylstilbene, 4'-methylphenylamino-α-phenylstilbene; 3-styryl-9-ethylcarbazole, 3 -(4-diethylamino)styryl-9-
A styrylcarbazole compound such as ethylcarbazole; or a polymer compound such as poly-N-vinylcarbazole is used.

Examples of electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4.7-dolinitro-9-fluorenone, 2,
4,5.7-tetranitro-9-fluorenone, 2,4
, 5.7-tetranitroxanthone, 2,4.8-trinidrothioxanthone, 2,6.8-trinitro-4H
-indeno(1.2-b)thiophen-4-one, 1,
3.7-trinitrodibenzothiophene-5.

Examples include 5-dioxide.

As the conductive support 1, for example, a plastic film having a conductive surface such as an aluminum vapor-deposited film;
Paper that has been treated to be water-resistant, solvent-resistant, and conductive; metal plates such as aluminum plates, zinc plates, copper plates, and stainless steel plates are used. In order to produce the printing original plate for electrophotographic engraving of the present invention, first, the charge generating substance described above is mixed with a binder resin such as a polyester resin, a polycarbonate resin, an acrylic resin, or a polystyrene resin, if necessary.

Organic solvents (tetrahydrofuran,
dioxane, dimethylformamide, acetone, methyl ethyl ketone, ethylene glycol monoethyl ether, ethyl acetate, cyclohexanone, etc.) and uniformly dispersed using a dispersion means such as a ball mill or an ultrasonic disperser is applied onto the conductive support 1. The charge generation layer 2 is formed by coating and drying.

Next, a solution in which a charge transport substance and silylated polyvinyl alcohol are dissolved in the same organic solvent as above is applied onto the charge generation layer 2 and dried to form a charge transport layer 3 that can be made hydrophilic. In addition, when a crosslinking agent is used, a coating solution prepared by adding a crosslinking agent such as a polyisocyanate compound to the solution is applied onto the charge generation layer 2, dried, and further heat-treated to cause a crosslinking reaction to make it hydrophilic. This is done by forming a charge transport layer 3 that can be oxidized.

When carrying out a crosslinking reaction, a heat treatment may be performed to cause a crosslinking reaction between the hydroxyl groups remaining without being silylated in the silylated polyvinyl alcohol and the polyisocyanate compound. This heat treatment can also be performed simultaneously with drying. The temperature and time of heat treatment vary depending on the type of silylating agent, degree of silylation, type of polyisocyanate compound, etc., but are generally 50 to 200°C for several minutes to
You can choose within a few hours.

In order to promote the crosslinking reaction, catalysts such as dibutyltin dilaurate, dibutyltin acetate, lead 2-ethylhexanoate, titanium tetrabutoxide, tin octoate, dibutyltin (2-ethylhexoate), 0 - Adding an appropriate amount of a metal compound such as phenyl soda, potassium oleate, bismuth nitrate, 2-ethylhexyl titanate, tin chloride, zinc naphthenate, antimony trichloride, or an amino acid such as triethylamine or triethylecidiamine. I can do it.

The hydrophilic charge transport layer 3 is mainly composed of silylated polyvinyl alcohol crosslinked with a charge transport substance and silylated polyvinyl alcohol or a polyisocyanate compound, but in order to improve the strength of the layer, other resins may be used. For example, polyester resin, polyamide resin, polycarbonate resin, acrylic resin, polystyrene resin, vinyl acetal resin or vinyl acetate resin can be added. However, in this case, the proportion of these resins contained in the entire layer is preferably 50% by weight or less. If the ratio is higher than this, the rate of hydrophilicization is slow and the hydrophilicity becomes insufficient in the parent wood treatment of the surface of the non-image area performed after one image is formed, resulting in background stains on the printed matter.

The proportion of the charge transport substance in the hydrophilic charge transport layer 3 is:
Preferably 10 to 95% by weight, more preferably 30 to 9% by weight
It is 0% by weight. Below this range, sensitivity is low, and above this range, printing durability is reduced.

Further, the thickness of the charge transport layer 3 is preferably 3 to 50 μm, and more preferably 5 to 20 μm. Below this range, charging will not be sufficient, and above this range, the residual potential will be high and cause staining of the background.

The proportion of the charge generating substance in the charge generating layer 2 is 10 to 80% by weight, preferably 20 to 70% by weight.If it is below this range, the sensitivity will be low, and if it is more than this, the mechanical strength of the layer will decrease and it is not practical. I can't stand it. The thickness of the charge generation layer 2 is preferably 0.05 to 5 μm, more preferably 0.1 to 2 μm. Below this range, the sensitivity is low, and above this range, the residual potential is high and causes background stains.

Plate making using the printing original plate for electrophotographic platemaking of the present invention first follows the usual electrophotographic method, and is uniformly charged in a dark place with a corona '41F electric appliance. An electrostatic latent image is formed by reflective image exposure using a light source such as a fluorescent lamp, contact image exposure through a transparent positive film, or scanning exposure using a laser beam such as a He-Ne laser, argon laser, or semiconductor laser. The electrolatent image is developed with toner and fixed by heating to obtain a toner image 4 on the electrophotographic photosensitive layer (FIG. 2).

Next, when the printing original plate on which this toner image has been formed is immersed in an acidic or alkaline hydrophilic treatment liquid, the surface of the non-image area that is not masked by the toner image (the surface of the charge transport layer 3) is made hydrophilic, and a good A printing plate is obtained (Figure 3)
. In FIG. 3, numeral 5 represents a hydrophilized portion.

Examples of oxidizing aqueous solutions include aqueous solutions of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, oxalic acid, acetic acid, and sulfamic acid; examples of alkaline aqueous solutions include sodium silicate,
Examples include aqueous solutions of inorganic salts such as sodium phosphate and sodium hydroxide, and aqueous solutions containing aqueous ammonia or organic amines such as triethanolamine and propatoolamine. Organic solvents such as ethanol, benzyl alcohol, ethylene glycol, and glycerin, surfactants, and the like may be added to these hydrophilic treatment liquids as necessary.

The rate of hydrophilization is determined by the type of silylated polyvinyl alcohol (
That is, the time can be easily reduced to about 20 to 60 seconds/plate by selecting appropriate conditions, although it varies depending on the type of silylating agent, degree of silylation) and the formulation of the hydrophilic treatment liquid.

Since the printing original plate of the present invention is subjected to parent wood treatment only in the non-image areas, it is preferable that the toner component contains a resin component having resistability to the hydrophilic treatment liquid.

This resin component may be anything as long as it is insoluble in the eluate; for example, acrylic resin using methacrylic acid, methacrylic acid ester, etc., vinyl acetate resin, copolymer of vinyl acetate and ethylene or vinyl chloride, etc. Union,
Vinyl chloride resin, vinylidene chloride resin, vinyl acetal resin such as polyvinyl butyral, polystyrene, copolymers of styrene and butadiene, methacrylic acid ester, etc., polyethylene, polypropylene and its chloride, polycarbonate, polyester resin, polyamide resin, phenol resin , xylene resin, alkyd resin, wax, polyolefin, wax, etc.

After the above-described plate-making process is completed, the printing plate material of the present invention becomes a printing plate having an image area covered with lipophilic toner and a surface of a non-image area that has been made highly hydrophilic.1 In normal lithographic printing, oil-based ink is used to create an image. It adheres only to the surface of the paper, resulting in good printed matter with no background stains.

EXAMPLES Below, the present invention will be explained in more detail with reference to Examples. In addition, "1 part" in the examples all represent parts by weight.

Example 1 1 part of a disazo pigment (charge generating substance) represented by the following structural formula (1), 19 parts of tetrahydrofuran, and polyvinyl butyral resin (Denka Butyral #4000-1:
A mixture consisting of 6 parts of a 5% by weight tetrahydrofuran solution (manufactured by Denki Kagaku Gyo Co., Ltd.) was sufficiently ground in a ball mill. The mixture was then taken out and diluted by adding 104 parts of tetrahydrofuran while stirring slowly. This solution was applied onto a polyester film (conductive support) with a thickness of about 100 μm on which aluminum was vapor-deposited, and heated to 80°C for 5
It was dried for a minute to form a charge generation layer with a thickness of about 0.5 μm.

A solution consisting of 10 parts of a charge transporting substance represented by the following structural formula (■) and 90 parts of a 12% by weight toluene solution of the trimethylsilylated polyvinyl alcohol obtained in the above production example was coated on this charge generation layer, and heated to 110°C. The mixture was dried for 10 minutes to form a hydrophilic charge transport layer having a thickness of about IO μm. , (blank below) The printing original plate for electrophotographic engraving prepared in this way was charged to a surface potential of approximately -800 volts by corona discharge in a dark place, and then imagewise exposed through a lens system using a halogen lamp to stabilize the printing plate. After forming the electrostatic latent image, it was developed with toner for copying machines and fixed by heating to form a toner image.

Next, in order to make the non-image area hydrophilic, it was immersed for 60 seconds in a hydrophilic treatment solution consisting of 1 part of 2% hydrochloric acid and 2 parts of ethanol.

The lithographic printing plate made in this way was mounted on an offset printing machine and printed according to the conventional method.

We were able to print over 3,000 good quality prints.

Example 2 In Example 1, 2.4 was used instead of the charge transport substance (■).
．． The same procedure as in Example 1 was carried out except that 7-trinitrofluorenone was used and positively charged in the plate-making process. When printing was performed using the obtained printing plate, three good prints were obtained.
I was able to print over ,000 sheets.

Example 3 1 part of a disazo pigment (charge generating substance) represented by the following structural formula (III), 0.33 part of polyester resin (manufactured by Toyobo Co., Ltd.: Vylon 200), and 60 parts of tetrahydrofuran
The mixture consisting of 1.5 parts was thoroughly ground in a ball mill. This dispersion was applied onto a polyester film on which aluminum was vapor-deposited on one surface, and dried at 80° C. for 5 minutes to form a charge generation layer with a thickness of about 0.5 μm.

On this charge generation layer, 10 parts of a charge transporting substance represented by the following structural formula (IV), 90 parts of a 12% by weight toluene solution of trimethylsilylated polyvinyl alcohol obtained in the above production example, and 1 part of toluene-2,4-diisocyanate were applied.
After drying at 110°C for 10 minutes, heat treatment was performed at 150°C for 30 minutes to give a thickness of about lOμI.
A charge transport layer that can be made hydrophilic was formed.

The printing original plate for electrophotolithography thus produced was processed and plate-made in the same manner as in Example 1, and when printing was performed using the obtained printing plate, more than 3,000 good prints were printed.

Example 4 A mixture consisting of 1 part of trisazo pigment (charge generating substance) represented by the following structural formula (V), 0.33 parts of polyvinyl butyral resin (same as in Example 1), and 12 parts of cyclohexanone was heated in a ball mill. After sufficiently pulverizing, 31 parts of cyclohexanone was added to this liquid while stirring to dilute it. This liquid was applied onto a polyester film on which aluminum was vapor-deposited, and dried at 120° C. for 5 minutes to form a charge generation layer with a thickness of about 0.5 μm. Next, the same charge transport layer as in Example 3 was formed on this charge generation layer.

When the printing original plate for electrophotographic engraving thus produced was processed and plate-made in the same manner as in Example 2, and the obtained printing plate was used for printing, more than 3,000 good-quality printed materials were printed.

[Effects] The printing original plate of the present invention has particularly high sensitivity compared to conventionally known printing original plates, and by selecting a charge generating substance, direct plate making can be performed using various light sources such as a He-Na laser and a semiconductor laser.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of the electrophotographic printing plate of the present invention. Also, Figures 2 and 3 are for explaining the plate-making process, and Figure 2 shows the state after toner image formation,
FIG. 3 shows the state after parent tree processing. FIG. 4 is a graph showing the infrared spectrum of trimethylsilylated polyvinyl alcohol used in the present invention. 1... Conductive support 2... Charge generation layer 3...
Charge transport layer 4...1 to Na1 Image 5...Hydrophilicized portion Patent applicant Rico Co., Ltd. - Agent Patent attorney Shigeru Tsukimura Other 1 Meimon 1 Figure

Claims (1)

[Claims] A charge-generating layer containing a charge-generating substance is provided on a conductive support, and a charge-generating layer containing a charge-generating substance is provided thereon, and polyvinyl alcohol silylated with a charge-transporting substance and a silylating agent, or a reaction between the silylated polyvinyl alcohol and a crosslinking agent. 1. A printing original plate for electrophotographic engraving, characterized in that the surface containing a substance is provided with a charge transport layer that can be made hydrophilic.