JPS6332564A - Printing plate material for electrophotomechanial process - Google Patents

Abstract

PURPOSE:To obtain a printing plate material high in sensitivity and printing resistance, and easy in plate making by forming an electrophotographic photosensitive layer containing an electric charge generating material, a charge transfer material, and a specified reaction product and capable of forming a hydrophilic surface on a conductive substrate. CONSTITUTION:The photosensitive layer 2 formed on the conductive substrate 1 and capable of forming a hydrophilic surface layer contains the charge generating material and the charge transfer material and polyvinyl alcohol silylated with a silylating agent in a silylating rate of 50-95% of the hydroxyl groups contained in the polyvinyl alcohol, or the reaction product of the silylated polyvinyl alcohol and a cross-linking agent, such as polyisocyanate compounds. The layer 2 is treated with an aqueous acidic or alkaline solution to hydrolyze the silyl ether groups to the initial hydroxyl groups, thus permitting the layer 2 to be made hydrophilic and made capable of printing.

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 -H 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 disadvantages of low printing durability, high cost per sheet, and high cost.

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. 18325, Special Publication No. 18325, Special Publication No. 1971
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 peel off due to the mechanical pressure applied during printing and the penetration of dampening water into the photosensitive layer and conductive treatment layer, destroying the parent wood layer on the surface. The printing force is about s,ooo to 10,000 sheets.

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 6001 or more. Therefore, there is a drawback that exposure cannot be performed using a low output and inexpensive He-Ne laser or semiconductor laser.

On the other hand, Special Publication No. 37-17162, Special Publication No. 3g-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. 45-5606 describes a method for producing a printing original plate with a parent wood treatment type on the surface of the 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 a surface layer comprising a vinylnythyl-maleic anhydride copolymer and a hydrophobic resin compatible therewith is provided on an electrophotographic photosensitive layer. 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 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 electrophotolithography of the present invention comprises polyvinyl alcohol silylated with a charge generating substance, a charge transporting substance and a silylating agent, or the silylated polyvinyl alcohol and a crosslinking agent on a conductive support. The invention is characterized in that it is provided with a child photographic photosensitive layer whose surface can be made hydrophilic by containing a reaction product with.

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

The present invention will be described in more detail below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing the basic structure of a printing original plate according to the present invention, in which 1 represents a conductive support and 2 represents an electrophotographic photosensitive layer that can be made hydrophilic.

In the image forming process by electrophotography, by image exposure after charging, the charge generating substance in the photosensitive layer 2 absorbs light in the irradiated areas, and carriers of electrons and holes are generated. Due to the electric field, one of these flows to the conductive support 1, and the other neutralizes the surface charge, forming an electrostatic latent image. At this time, the surface of the photosensitive layer 2 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, it will absorb water and electrostatic latent image cannot be retained).

Next, the electrostatic latent image is developed with toner charged to the opposite polarity to the surface charge and fixed, forming a toner image on the photosensitive layer 2. As for printing.

The lipophilicity of the toner image thus formed (1!A
The surface of the photosensitive layer 2 needs to be hydrophilic at the time of printing because this is done based on the difference between the ink property (ink property) and the hydrophilicity of the non-image area.

Thus, in addition to forming an electrostatic latent image, the photosensitive layer 2 is required to have the following functions: (1) When the surface changes from hydrophobicity necessary for forming an electrostatic latent image to hydrophilicity necessary for printing. The silylated polyvinyl alcohol or the reaction product of the silylated polyvinyl alcohol and a crosslinking agent used in the photosensitive layer 2 in the present invention is hydrophobic in nature and has sufficient resistance to retain an 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.

The charge generating substance used in the photosensitive layer 2 of the present invention is as follows:
Examples include inorganic compounds such as tin oxide, titanium oxide, zinc sulfide, selenium, 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 Orange R;

Astrazone Yellow 3GL, Astrazone Red 6B
Astrazon dyes such as; Cyanine dyes such as Eisen Astrafuroxin FF; Xanthine dyes such as Rhodamine B; Cationic dyes such as pyrylium dyes.

(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) A eutectic complex formed from a pyrylium salt dye and a polycarbonate 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 hydrophilic photosensitive layer 2 can be obtained by reacting polyvinyl alcohol with a silylating agent in an organic solvent. As a silylating agent.

Trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, t-butyldimethyldichlorosilane, dimethylchlorosilane.

Halosilanes such as diphenyldichlorosilane, triphenylchlorosilane, triethylfluorosilane, trimethylbromosilane; hexamethyldisilazane, N, N
- Silylamines such as 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-trimethylsilyl-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 can be carried out using the silylating agents mentioned above, for example, as described by Bredereck.

K, 5trunk, H, Menrady Die
MakromolekuLareChemie 126
．． 139 (1969) or Japanese Patent Application Publication No. 55-16461
As described in Publication No. 4, etc., the reaction is carried out in the presence of an organic solvent that does not react with the silylating agent, such as N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, dioxane, toluene, pyridine, triethylamine, etc., or can be easily synthesized by direct reaction without using a solvent.

The raw material polyvinyl alcohol has a saponification degree of 98.
Either ~100 mol% fully saponified polyvinyl alcohol or 70-98 mol% 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 layer will not have sufficient water resistance and will also have low rigidity resistance. Also.

When reacting with a crosslinking agent, in order to react the hydroxyl groups remaining without being silylated in the silylated polyvinyl alcohol with the crosslinking agent, in the silylation reaction, 95
It is preferable to limit it to about %. 95% silylation
If it is more than that, crosslinking will not be carried out sufficiently and good rigidity resistance will not be obtained.

A typical example of the crosslinking agent is a polyisocyanate compound. Polyisocyanate compounds include toluene-2,4-diisocyanate and toluene-2,6-diisocyanate.
Diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, triphenylmethane-4,4', 4'
- Aromatic polyisocyanates such as triisocyanate, tris(p-isocyanate phenyl) thiophosphite, polymethylene polyphenyl isocyanate, xylylene diisocyanate, or aliphatic polyisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate, or dimers thereof , trimer, etc.

Here, an example of silylated polyvinyl alcohol + M construction 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 triethylamine and 25,213 parts by weight of trimethylchlor were added and reacted at room temperature for 3.5 hours to form trimethylsilyl. 9.6 parts by weight of polyvinyl alcohol were obtained.

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

The photosensitive layer 2 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-ossadiazole, 2,5-bisC4 -(4-diethylaminostyryl)phenyl)-
Oxadiazole compounds such as 1,3゜4-oxadiazole, 2-(9-ethylcarbazolyl-3-)-5-(4-diethylaminophenyl)-1,3,4-oxadiazole; 2 -vinyl-4-(2-chlorophenyl)
-5-(4-diethylamino)oxazole, 2-(4
-diethylaminophenyl)-4-phenyloxazole; 1-phenyl-3-(4
Pyrazoline compounds such as -diethylaminostyryl)-5-(4-diethylaminophenyl)pyrazoline, 1-phenyl-3-(4-dimethylaminostyryl)-5-(4-dimethylaminophenyl)pyrazoline; 2゜2'
-Diphenylmethane compounds such as dimethyl-4,4'-bis(diethylamino)triphenylmethane, 1,1-bis(4-dibenzylaminophenyl)propane, tris(4-diethylaminophenyl)methane; 9-(
4-dimethylaminobenzylidene) fluorene, 3-(
Fluorene compounds such as 9-fluorenonedene)-9-ethylcarbazole; Styryl anthracene compounds such as 9-(4-diethylaminostyryl) anthracene, 9-bromo-10-(4-diethylaminostyryl) anthracene; 1,2-bis( Distyrylbenzene compounds such as 4-diethylaminostyryl)benzene and 1,2-bis(2°4-dimethoxystyryl)benzene;
9-Ethylcarbazole-3-aldehyde 1-methyl-
1-phenylhydrazone, 9-ethylcarbazole-3
-aldehyde 1-benzyl-1-phenylhydrazone,
4-diethylaminobenzaldehyde 1,1-diphenylhydrazone, 2,4-dimethoxybenzaldehyde 1
- Hydrazone compounds such as benzyl-1-phenylhydrazone and 4-diphenylaminobenzaldehyde 1-methyl-1-phenylhydrazone; Stilbene compounds such as 4-diphenylaminostilbene, 4-dibenzylaminostilbene, and 4-ditolylaminostilbene; 1-
(4-diphenylaminostyryl)naphthalene, 1-(
Styrylnaphthalene compounds such as 4-dibenzylaminostyryl)naphthalene; 4'-diphenylamino-α-
Phenylstilbene, 4'-methylphenylamino-α
- α-Phenylstilbene compounds such as phenylstilbene; 3-styryl-9-ethylcarbazole, 3-(
styrylcarbazole compounds such as 4-diethylamino)styryl-9-ethylcarbazole; or poly-
A polymer compound such as N-vinylcarbazole is used.

An example of an electron transport substance is chloranil.

Bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4.7-dolinitro-9-fluorenone, 2,4,5.7-tetranitro-9-fluorenone, 2,4,5.7-titranitroxanthone, 2 ,4.
8-Trinidrothioxanthone, 2,6.8-)-linitro 4H-indeno(1,2-b)thiophene-4-
on.

1.3.7-trinitrodibenzothiophene-5゜5-
Dioxide, etc.

For the photosensitive Fyj2, these hole or electron transport substances are used alone or in combination.

As the tetraelectric support 1, for example, a plastic film having a conductive surface such as an aluminum vapor-deposited film;
Paper that has been treated for water resistance, solvent resistance, and conductivity; metal plates such as aluminum plates, zinc plates, copper plates, and stainless steel plates are used.

To produce the printing original plate for electrophotographic engraving of the present invention, first, silylated polyvinyl alcohol is mixed with a suitable organic solvent (toluene, tetrahydrofuran, dioxane, dimethylformamide, acetone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethyl acetate, cyclohexanone, etc.). A charge-generating substance is added to the solution dissolved in the liquid, and the mixture is dispersed and mixed using methods such as ball milling and ultrasonic dispersion.
A liquid prepared by dissolving a charge transport substance in a charge liquid is applied onto the conductive support 1 and dried to form an electrophotographic photosensitive layer 2.

In addition, when using a crosslinking agent, a coating solution prepared by adding a crosslinking agent such as a polyisocyanate compound to the solution is applied onto the conductive support 1, dried, and further heat-treated to cause a crosslinking reaction. This is carried out by forming an electrophotographic photosensitive layer 2 that can be made hydrophilic.

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), o -Phenyl soda, potassium oleate, bismuth nitrate, titanium I! Appropriate amounts of metal compounds such as 22-ethylhexyl, tin chloride, zinc naphthenate, and antimony trichloride, or amino acids such as triethylamine and triethylecidiamine can be added.

The hydrophilic photosensitive layer 2 is mainly composed of silylated polyvinyl alcohol crosslinked with a charge generating substance, a charge transporting substance, and silylated polyvinyl alcohol or a polyisocyanate compound, but in order to improve the strength of one layer,
Other resins such as polyester resins, polyamide resins, polycarbonate resins, acrylic resins, polystyrene resins, vinyl acetal resins or vinyl acetate resins 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 hydrophilicity will be slow and the hydrophilicity will be insufficient in the parent wood treatment of the non-image area surface after image formation, resulting in background stains on printed matter.

The proportion of the charge transport substance in the hydrophilic photosensitive layer 2 is preferably 10 to 90% by weight, more preferably 20 to 70% by weight. Below this range, sensitivity is low, and above this range, printing durability is reduced. Also.

The proportion of the charge generating substance in the photosensitive layer 2 is 0.1 to 50% by weight.
, preferably 1 to 30% by weight. Below this range, sensitivity is low, and above this range, the mechanical strength of the layer decreases and is not practical. The thickness of the photosensitive layer 2 is preferably 3 to S.
0 .mu.m, more preferably 5 to 20 .mu.m. Below this range, charging will not be sufficient, and above this range, the residual potential will be high and cause staining of the background.

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 using a corona charger or the like, and then charged using a tungsten lamp, halogen lamp, xenon lamp, or fluorescent lamp. An electrostatic latent image is formed by reflective image exposure using a light source such as a 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 latent image is developed with toner and fixed by heating to form a toner image 3 on the electrophotographic photosensitive layer.
(Figure 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 photosensitive M2)
is made hydrophilic and a good printing plate is obtained (FIG. 3) 6 In FIG. 3, 4 represents the portion that has been made hydrophilic.

Examples of oxidizing aqueous solutions include hydrochloric acid, '8Jt'v, nitric acid,
Examples include aqueous solutions of phosphoric acid, oxalic acid, acetic acid, sulfamic acid, etc.Alkaline aqueous solutions include, for example, aqueous solutions of inorganic salts such as sodium silicate, sodium phosphate, and sodium hydroxide, ammonia water, or organic salts such as triethanolamine and propatoolamine. Examples include aqueous solutions containing amines. These hydrophilic treatment solutions include ethanol, benzyl alcohol, ethylene glycol,
Organic solvents such as glycerin, surfactants, etc. may be added.

The rate of hydrophilization is determined by the type of silylated polyvinyl alcohol (
In other words, it varies depending on the type of silylation agent, degree of silylation), source of parent wood treatment solution, etc.

By selecting appropriate conditions, the printing time can be easily reduced to about 20 to 60 seconds/plate.

Since the printing original plate of the present invention is subjected to hydrophilic treatment only on the non-image areas, it is preferable that the toner component contains a resin component having resistivity in 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 esters, etc., polyethylene, polypropylene and its chloride, polycarbonate.

polyester resin, polyamide resin, phenolic resin,
These include xylene resin, alkyd resin, wax, polyolefin, and wax.

The printing original plate of the present invention is produced after the above plate-making process is completed.

The printing plate has an image area covered with lipophilic toner and a non-image area surface that is highly hydrophilic.In normal planographic printing, oil-based ink adheres only to the image area, resulting in good printed matter without background stains. can get.

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

Example 1 Two parts of a disazo pigment (charge generating substance) represented by the following structural formula (1) and 20 parts of tetrahydrofuran were mixed and thoroughly ground in a ball mill. Next, to this dispersion, 90 parts of a 12% by weight toluene solution of trimethylsilylated polyvinyl alcohol obtained in the above production example and the following structural formula (
7 parts of the charge transport substance represented by II) was added and further dispersed sufficiently to prepare a coating solution.

This coating solution was applied to the surface to a thickness of 100 mm by vapor-depositing aluminum.
The mixture was coated on a polyester film (conductive support) having a thickness of about 20 μm and dried at 80° C. for 2 minutes and at 110° C. for 10 minutes to form a hydrophilic electrophotographic photosensitive layer with a thickness of about 20 μm.

The printing original plate for electrophotographic engraving thus prepared 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 form an electrostatic latent image. A toner image was formed by developing with toner for copying machines and fixing with heat.

Next, in order to make the non-image area hydrophilic, 1 part of 2% by weight hydrochloric acid,
It was immersed for 60 seconds in a parent tree treatment solution consisting of 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 2 parts of a disazo pigment (charge generating substance) represented by the following structural formula (m) and 20 parts of tetrahydrofuran were mixed and thoroughly ground in a ball mill. 90 parts of a 12% by weight toluene solution of trimethylsilylated polyvinyl alcohol prepared by
V) 7 parts of charge carrier lR and toluene-
1 part of 2,4-diisocyanate was added and further sufficiently dispersed to prepare a coating solution.

This coating solution was coated on the same conductive support as in Example 1,
After drying at 80℃ for 2 minutes and at 110℃ for 10 minutes,
C. for 30 minutes to form a hydrophilizable charge transport layer with a thickness of about 20 microns.

When the printing original plate for electrophotographic printing produced in this way was plate-made in the same manner as in Example 1 and printed using the obtained lithographic printing plate, more than 3,000 good printed materials could be printed. Ta.

Example 3 In Example 2, instead of the charge transport substance (n), 2.4
．． An electrophotographic printing original plate was prepared using 7-trinitrofluorenone.

Plate making was carried out in the same manner as in Example 2 except that this original plate was charged to about -800 volts during the plate making process, and when printing was performed using the obtained printing plate, good printed matter was obtained at 3,000 volts.
I was able to print more than one page.

Example 4 In Example 2, a trisazo pigment represented by the following structural formula (V) was used instead of the charge generating substance (m), and the compound (n) used in Example 1 was used instead of the charge transporting substance (fV).
An original plate for electrophotolithography was formed using the following.

When the printing original plate for electrophotographic engraving thus produced was treated and plate-made as in Example 2, and the resulting printed matter was used for printing, more than 3,000 good-quality printed matter could be 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-Ne 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. Furthermore, FIG. 4 is a graph showing the infrared absorption spectrum of trimethylsilylated polyvinyl alcohol.

Claims (1)

[Claims] 1. The surface of the conductive support containing polyvinyl alcohol silylated with a charge generating substance, charge transporting substance and silylating agent or a reaction product of the silylated polyvinyl alcohol and a crosslinking agent can be made hydrophilic. A printing original plate for electrophotographic engraving characterized by being provided with an electrophotographic photosensitive layer.