JPH02173656A - Electrophotographic planographic printing plate material - Google Patents

Abstract

PURPOSE:To prevent the failure of an electrophotographic photosensitive layer by friction by incorporating the granular matter of the secondarily bound hard particles of zinc oxide of a specific grain size bound by an electron ray curing resin consisting of a specific polymer into the photosensitive layer to form projecting parts on the surface of the layer. CONSTITUTION:The electrophotosensitive layer 2 of the photoconductive zinc oxide- resin dispersion system contg. an insulating resin binder and the many fine particles of the photoconductive zinc oxide dispersed in this binder is provided on a base 1 having water resistance, by which the electrophotographic planographic printing plate material is formed. The electron ray curing resin consisting of the styrene/butadiene copolymer cured by the generation of inter-molecular crosslinking by irradiation of electrons and the granular matter of the secondarily bound hard particles 3 of the zinc oxide having 20 to 60mum average grain size of the fine particle assemblage of the zinc oxide bound by this resin are incorporated into this layer 2. The projecting parts 4 are formed by these particles 3, by which the failure of the photosensitive layer by friction is prevented and the printed matter having high image quality with decreased scumming of printing is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic lithographic printing plate material. More specifically, the present invention relates to an improved electrophotographic lithographic printing plate material that does not cause or has less occurrence of printing background staining due to friction.

[Conventional technology]

As printing plate materials for direct plate making using electrophotography, for example, Japanese Patent Publication No. 47-47610, Japanese Patent Publication No. 47-47,
8-40002, Japanese Patent Publication No. 48-18325, Japanese Patent Publication No. 51-15766, Japanese Patent Publication No. 51-25761, etc., having an electrophotographic photosensitive layer of a photoconductive zinc oxide-resin dispersion system. Printing plate materials are known.

Such printing plate materials are inexpensive, relatively sensitive, and
It has advantages such as a simple plate-making process.

Electrophotographic printing plates are usually produced by subjecting the printing plate material to corona charging, exposure, development and fixing processes according to a desired pattern using a plate making machine, thereby forming the pattern on the photoconductive layer. Obtained by forming a toner image.

Such electrophotographic development methods include a dry development method that uses a mixture of toner and a carrier such as iron powder as a developer, and a wet development method that uses a developer in which toner is dispersed in an organic solvent such as Isopar. There is.

When plate making is performed using the wet developing method described above, there are advantages such as good reproducibility of halftone images, excellent resolution, and short plate making time. The production of lithographic printing plates is widely used.

Electrophotographic lithographic printing plate materials need to have various properties required as lithographic printing plate materials in addition to the image properties generally required as electrophotographic materials.

For example, as an offset printing plate material, it is possible to make non-image areas hydrophilic by treating the surface of the electrophotographic photosensitive layer with an etchant, and it is also suitable for use with large amounts of dampening water used during printing. On the other hand, it is necessary to have excellent water resistance.

The electrophotographic photosensitive layer is produced by coating a support with a paint containing a photoconductive pigment such as zinc oxide or titanium oxide, an insulating resin binder, a sensitizing dye, and a solvent, and then drying the coating. It is formed.

As insulating resin binders, highly hydrophilic acrylic ester copolymers, methacrylic ester copolymers, vinyl acetate copolymers, Silicone resin, butyral resin, etc. are used. Additionally, functional groups such as acrylic acid, methacrylic acid, and maleic acid are usually copolymerized with these polymers for the purpose of improving image quality, paint physical properties, and mechanical strength of the coating film. .

Conventional electrophotographic photosensitive layers using such resin binders have insufficient surface strength and are therefore prone to wear.
The electrophotographic photosensitive layer is damaged by pressure and friction during the manufacturing process of electrophotographic lithographic printing plate materials, during transportation, or during feeding in the plate-making machine, and toner adheres to the damaged areas during development. Therefore, when such a plate material is used as a printing plate, it causes scumming on printed matter.

Attempts have been made to increase the pressure resistance of the electrophotographic photosensitive layer by using polystyrene resin or polymethyl methacrylate resin, which have a high glass transition temperature, as an insulating resin binder, but these resin binders lack flexibility and flexibility. Since the flexibility is insufficient, if a printing plate is formed using this, it tends to crack during use, which causes a decrease in stiffness resistance.

In addition, as a method of increasing the strength of the coating film of the electrophotographic photosensitive layer, it is possible to increase the blending ratio of the insulating resin binder, but if the resin binder ratio is high (the zinc oxide content will be relatively and therefore the photoconductivity of the resulting photosensitive layer is reduced, good image quality is not obtained, the etching effect is insufficient, and the resulting prints are generally smudged and unsatisfactory. be.

Furthermore, in the zinc oxide photoreceptor for offset printing plates disclosed in JP-A No. 59-40654, acrylic-butadiene copolymer-coated zinc oxide particles having a glare of 20 to 50 are dispersed in the electrophotographic photosensitive layer. describes that protrusions are formed on the surface of a photosensitive layer to thereby prevent or reduce scumming of printed matter caused by mechanical friction of the photosensitive layer. However, even when using this acrylic cyclodiene copolymer-coated zinc oxide particles, the strength of the protrusions obtained is insufficient. The photosensitive layer is damaged by pressure and friction, causing background stains on printed matter.

[Problem to be solved by the invention]

The present invention aims to solve the above-mentioned problems of conventional lithographic printing plate materials using electrophotography, and to provide an electrophotographic printing plate material in which there is no or little occurrence of printing background staining due to friction. .

Furthermore, the present invention aims to provide an electrophotographic lithographic printing plate material that has a spectral sensitivity that can be recorded by light beams of various wavelengths such as He-Ne laser light or semiconductor laser light, and has no or little printing background stain. It is something to do.

[Means and effects for solving the problem] In order to solve the above problem, the present inventors conducted extensive research and found that a large number of hard particles of a specific size are used on the surface of the electrophotographic photosensitive layer. The present invention has been completed based on the discovery that the above problem can be solved by forming protrusions in a scattered manner.

The electrophotographic lithographic printing plate material of the present invention comprises: a water-resistant conductive support; an insulating resin binder formed on one surface of the support; and an insulating resin binder dispersed in the resin binder. and an electrophotographic photosensitive layer containing a large number of photoconductive zinc oxide fine particles, wherein a large number of granular bodies are further dispersed in the electrophotographic photosensitive layer, and the granular bodies are dispersed in the electrophotographic photosensitive layer. A large number of protrusions are formed on the surface of the photosensitive layer, and the granules forming the protrusions are made of an electron beam-cured resin made of a styrene-butadiene copolymer that is cured by intermolecular crosslinking by electron beam irradiation. , consisting of a plurality of zinc oxide fine particle aggregates bound by the cured resin, and having an average particle size of 20 to 60 feet, secondary bound hard particles of zinc oxide. It is something.

The structure of the printing plate material of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an explanatory cross-sectional view showing the basic structure of the lithographic printing plate material of the present invention.

In FIG. 1, an electrophotographic photosensitive material N2 having a thickness of, for example, about 20 IM and containing a large number of fine zinc oxide particles and an insulating resin binder for bonding them is provided on a support 1. In FIG. In this electrophotographic photosensitive layer 2, a plurality of zinc oxide fine particles are further bonded together by a large number of secondary zinc oxide particles bound by a binder made of a styrene-butadiene copolymer cured by electron beam irradiation. Hard particles 3 are dispersed, thereby forming a large number of protrusions 4.

As mentioned above, the conventional lithographic printing electrophotographic window light layer generally uses a soft resin as a binder, so its surface is soft and therefore susceptible to wear and/or damage. Therefore, when the surface of such a photosensitive layer is mechanically rubbed, the electrophotographic sensitivity of the rubbed area decreases, the potential is no longer attenuated, and toner adheres to the rubbed area during the development process. This causes printing stains on printed matter and image deterioration.

In contrast to such conventional techniques, the electrophotographic photosensitive layer of the present invention has the following advantages:
Since hard particles of a specific size are scattered on the layer surface and form protrusions, the friction of the electrophotographic photosensitive layer is
The load is concentrated on the protrusions, and therefore mechanical abrasion of the entire photosensitive layer is prevented or suppressed, thereby preventing the occurrence of background smudges on printed matter. Furthermore, the styrene-butadiene resin binding and coating the zinc oxide fine particles is cured by electron beam irradiation. That is, the double bond group at the 3.4-position of the 1.2-added butadiene moiety and the double bond group at the 2.3-position of the 1.4-added moiety of the styrene-butadiene copolymer are opened by electron beam irradiation. These three-dimensionally cured resins, which form intermolecular crosslinks, are hard and significantly improve various physical properties such as abrasion resistance and solvent resistance of the printing plate material obtained by the present invention.

In order to produce the zinc oxide secondary binding hard particles in the present invention, zinc oxide fine (secondary) particles with a particle size of about 0.2 to 0.5 IM are dispersed in a styrene-butadiene copolymer latex, This is dried and solidified.

Next, this solidified product is crushed into particles having an average particle size of about 20 to 60 mm.

In the present invention, the step of irradiating the styrene-butadiene copolymer resin with electron beams involves adding zinc oxide fine particles with a particle size of about 0.2 to 0.5 to the styrene-butadiene copolymer latex. It may be applied to a solidified product obtained by dispersing and drying, or the solidified product may be dispersed and dried to obtain a solidified product with an average particle size of 20.
It is also possible to grind the particles to about 60 mm and apply the powder to the obtained pulverized particles.

As the electron beam irradiation machine used for manufacturing the zinc oxide secondary bound hard particles of the present invention, it is advantageous to use a curtain beam system which is relatively inexpensive and can provide a large output. At this time,
Generally the accelerating voltage is 100-300 v and the absorbed dose is 0.5-10 Mrad. Also, during electron beam irradiation,
It is desirable that the oxygen concentration in the atmosphere is 500 pμm or less; if this oxygen concentration is greater than 500 pμm,
Oxygen acts as a retarder for the curing reaction of the styrene-butadiene copolymer, resulting in insufficient curing.

In the production of the secondary bound zinc oxide hard particles of the present invention, when an emulsion of an organic compound having at least two or more acryloyl groups in one molecule is used together with the styrene-butadiene copolymer latex, the secondary bound hard particles obtained are The strength of the protrusion formed by the deposited particles can be further improved.

Such reinforcing organic compounds having two or more acryloyl groups in one molecule include (1) acrylates of aliphatic, alicyclic, and araliphatic di- to hexavalent polyhydric alcohols and polyalkylene glycols; .

(2) Polyacrylate of polyhydric alcohol obtained by adding alkylene oxide to aliphatic, alicyclic, or araliphatic di- to hexavalent polyhydric alcohol.

(3) Polyacryloyl alkyl phosphate ester.

(4) Polyester acrylate.

(5) Polyurethane acrylate.

(6) Epoxy acrylate.

etc. can be mentioned. Specifically, examples of this reinforcing organic compound include 1,4-butadienediol diacrylate, 1,6-hexanediol diacrylate,
Polyethylene glycol diacrylate, polypropylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, hydroxypivalic acid neopentyl glycol diacrylate, epichlorohydrin-modified glycerol triacrylate, 1 ，
Examples include 3-butylene glycol dimethacrylate.

The reinforcing organic compound having an acryloyl group as described above is generally prepared as an oil-in-water emulsion by adding water with stirring in the presence of a surfactant. Examples of surfactants include fatty acid salts, higher alcohol sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, formanium naphthalene sulfonate condensates, dialkyl sulfone succinates, alkyl phosphate salts, and polyoxyethylene sulfate salts. anionic surfactants such as, and
Nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, sorbitan fatty acid ether, polyoxyethylene sorbitan fatty acid ether, polyoxyethylene acyl ester, etc., as well as alkyl amino acids, quaternary ammonium salts Cationic surfactants such as , polyoxyethylene alkyl amines, and the like are used.

Furthermore, one or more water-soluble polymers such as polyvinyl alcohol may be used alone or in combination. These surfactants generally have a zero resistance to acryloyl compounds.
．． 01-20% by weight, particularly preferably 0.05-
It is used in a range of 10%.

The emulsion of the reinforcing organic compound prepared as described above preferably has a solid content ratio of 80% by weight or less, more preferably 60% by weight or less, relative to the styrene-butadiene copolymer latex. preferable. If the amount of the reinforcing organic compound exceeds 80% by weight, the hardness of the cured resin may become excessive, making it difficult to form pulverized particles.

The average particle size of the zinc oxide secondary binding particles in the present invention is 2
It is classified into about 0 to 60. When the particle size is larger than 60 knots, the images of the resulting plate-made and printed matter become rough. Furthermore, if the particle size is smaller than 20 tones, the effect of preventing wear on the resulting photosensitive layer will be insufficient, and scumming will occur in printed matter. The blending ratio of styrene-butadiene copolymer and zinc oxide fine particles is 1:0.5 to 1:15
(weight), and more preferably from 1 to 5:5. Note that the zinc oxide secondary binding particles may contain additives such as a dispersant and a dye sensitizer, if necessary.

In the electrophotographic photosensitive layer of the present invention, the zinc oxide secondary binding particles having a particle size of 20 to 60 tnn are combined with ordinary photoconductive zinc oxide-
Dispersed in an insulating resin binder-based electrophotographic photosensitive layer coating solution, and coating this coating solution on a water-resistant conductive support so that the film thickness is 20 to 30 II m (after drying), Formed by drying.

On the surface of the electrophotographic photosensitive layer formed in this way,
A large number of protrusions are formed by the zinc oxide secondary binding hard particles. Although there is no particular limitation on the height of the protrusion, it is preferably 5 to 50 degrees, more preferably 5 to 254 degrees. Furthermore, the amount of the zinc oxide secondary binding particles added is as follows:
The content is preferably 0.05 to 2.0% by weight, more preferably 0.1 to 1.0% by weight, based on the weight of the electrophotographic photosensitive layer.

The insulating binder resin used in the electrophotographic photosensitive layer may be composed of a single type of resin, or
A mixture of binder resin of Li or more may also be used. Such binder resins include, for example, polyester resins,
Acrylic resin, epoxy resin, polycarbonate resin,
Melamine resins, butyral resins, silicone resins, polyurethane resins, polyamide resins, alkyd resins, polystyrene resins, xylene resins, phenoxy resins, and the like are used.

In addition to photoconductive zinc oxide, the electrophotographic photosensitive layer used in the present invention contains various additives such as dyes and electron-accepting substances that have been conventionally used, mainly for the purpose of improving electrophotographic properties such as sensitivity. It may contain agents and additives as appropriate. In addition, in order to have sensitivity to the wavelength of the semiconductor laser beam,
Compounds of the following formats (1) and (II) having maximum photosensitivity in the range of 700 to 11,000 nm may be included as exacerbating agents.

and [However, in the above formula, R, , R, and R1 each independently represent CJ, C211s, and -CHz Cl
l = represents an l member selected from CH□ group, preferably CILz CH= CHz group, and X is Br, C
j! and I atoms, cIlo, and OSO! −□CI
It represents one member selected from three groups, preferably CZO. ] As the water-resistant conductive support for the electrophotographic lithographic printing plate material of the present invention, conventional supports such as metal sheets, metal foils, paper laminated with metal foils, plastic films, and vapor-deposited metal layers can be used. The electrical conductor can be selected from paper and plastic film that has a conductive coating, paper that has been subjected to conductive treatment, plastic film, and the like.

To make a printing plate from the lithographic printing plate material of the present invention, first, according to the usual electrophotographic method, the printing plate material is uniformly charged in a dark place using a corona charger or the like, and then charged with a tungsten lamp or a halogen lamp. , reflection image exposure using a light source such as a xenon lamp or fluorescent light, contact exposure through a transparency film, or He-N
Scanning exposure with laser light such as e-laser light, argon laser light, or semiconductor laser light is performed to form an electrostatic latent image on the electrophotographic photosensitive layer, and this electrostatic latent image is developed with toner and fixed by heating. to form a toner image on the plate.

Next, the non-image areas of the obtained printing plate are desensitized using a normal desensitization treatment liquid, and the obtained printing plate is used by being mounted on an offset printing machine.

〔Example〕

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

However, these examples are not intended to limit the scope of the invention. In addition, "part j" and "%" in the examples represent parts by weight and weight % unless otherwise specified.

1- The following composition: Zinc oxide (manufactured by Sakai Chemical Co., Ltd., 5AZEX #2000) 90
A mixed solution containing 0.02 parts and 120 parts of rose bengal toluene was dispersed with a sand grinder to obtain a photosensitive liquid.

Separately, the following composition: Zinc oxide (manufactured by Sakai Chemical Co., Ltd., 5AZEX +12000)
40 parts water
A mixture containing 18.3 parts of 2 parts of
After being dispersed for 0 minutes, it was dried and solidified at 100°C for 24 hours. This solidified product was ground in a mortar, and the resulting particles were then classified using a sieve to obtain particle sizes ranging from 20 to 60. Next, the classified particles were exposed to 4 electron beams at an accelerating voltage of 165 Kv.
The copolymer in the particles was cured by irradiation at an absorbed dose of Mrad to obtain secondary binder particles of zinc oxide.

Next, the obtained secondary binding particles are added to the photosensitive liquid in an amount of 1% by weight based on the solid weight of the photosensitive liquid, and the mixed liquid is stirred and dispersed with a stirrer to form an electrophotographic photosensitive layer. It was made into a liquid.

As a support, a base paper with a basis weight of 80 g/rrf and a thickness of 10 nm was used.
A composite sheet formed by laminating aluminum foil was used.

The coating solution was applied onto the aluminum foil surface of the support and dried to form an electrophotographic photosensitive layer. The thickness of this photosensitive layer was 22μ. The height of the many protrusions formed on the surface of the photosensitive layer was approximately 30n at the highest, and 20pTn on average.

In order to evaluate the scratch resistance of the electrophotographic photosensitive layer thus formed, the printing plate was conditioned for 24 hours at 25°C in a 150% R1+ atmosphere.
Layer another printing plate on the surface of this electrophotographic photosensitive calendar so that its back side is in contact with the surface of the photosensitive layer, and place a 3 kg weight (
7 cm in diameter) and pulled the upper plate once by a length of about 20C111 to damage the surface of the photosensitive layer.

Thereafter, plate making and printing were performed using this plate, and the degree of printing soiling caused by damaged areas (particularly non-image areas) was sensory evaluated.

Plate making and printing were performed as follows. That is, a plate is made from the printing plate material using an ITEK 235 plate making machine, the printing plate is desensitized with an etchant (ITEK product), and then an offset printing machine (Ryobi 2800CD, Synflo type) is used. The image quality of the resulting printed matter was examined, especially the scumming caused by friction.

The results are shown in Table 1.

Blood Spot I The following composition: Zinc oxide (manufactured by Sakai Chemical Co., Ltd., 5AZEX 112000)
A mixed solution consisting of 90 parts of rose bengal, 0.02 parts, and 120 parts of toluene was dispersed with a sand grinder to obtain a photosensitive liquid. On the other hand, the following composition: Zinc oxide (manufactured by Sakai Chemical Co., Ltd., 5AZEX #2000)
After dispersing a mixed solution consisting of 40 parts water and 18.3 parts using a homomixer for 20 minutes,
The solidified product was dried and solidified at 100°C for 24 hours, and the resulting solidified product was ground in a mortar, and the secondary bound particles were then classified using a sieve to adjust the particle size to 20-60.

Next, the classified particles were irradiated with an electron beam at an accelerating voltage of 165 Kv to an absorbed dose of 4 Mrad to harden the copolymer resin in the particles to obtain zinc oxide secondary bound particles. Thereafter, in the same manner as in Example 1, a coating liquid was prepared and an electrophotographic lithographic printing plate was produced. Using the obtained electrophotographic printing plate, the printing background stain was evaluated in the same manner as in Example 1.

The results are shown in Table 1.

Incidentally, the TMPTA emulsion was prepared as follows. That is, 40 parts of TMPTA and 40 parts of water were added to 20 parts of a 10% aqueous solution of Emulgen 930 (manufactured by Kao Atlas, polyoxyethylene nonylphenyl ether), and the mixture was dispersed with an ultrasonic disperser (sonifier). A 40% emulsion of TMPTA was prepared.

Main composition below: Zinc oxide (manufactured by Sakai Chemical Co., Ltd., 5AZEX 112000)
90 parts polyacrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., LR-188) 25 parts sensitizer (compound of -formation (n) above) > 0.02 part toluene
A mixed liquid consisting of 120 parts was dispersed using a sand grinder to obtain a photosensitive liquid.

Next, the same operation as in Example 1 was performed on the photosensitive solution. However, the secondary binder particles of zinc oxide are mixed with the solid liI of the photosensitive liquid!
It was added at a blending ratio of i amount % to prepare a coating solution for forming an electrophotographic photosensitive layer.

The obtained electrophotographic printing plate was heated at 25°C, 150%RH.
Conditioning was performed for 24 hours in a dark place in an atmosphere of
, wavelength 780 nm) was irradiated and scanned. Next, the electrophotographic photosensitive layer irradiated with laser light was developed using a positively charged toner (manufactured by ITEC). After development, apply etchant (IT
EK Co., Ltd. product) to make it fat-free and offset printing machine (
The images were printed using Ryobi's 2800CD, Synflo type), and the image quality of the printed matter was examined, especially the background smudges caused by scratches.

The results are shown in Table 1.

Fuho endo The following composition: Zinc oxide (manufactured by Sakai Chemical Co., Ltd., 5AZEX +12000)
90 parts polyacrylic resin (manufactured by Mitsubishi Ray-Yon Co., Ltd., LR-188) 2
5 parts sensitizer (compound of -formation (n) above > 0.02
A mixed solution consisting of 120 parts of toluene was dispersed using a sand grinder to obtain a photosensitive liquid.

Next, the same zinc oxide secondary binding particles as in Example 2 were added to the photosensitive solution at a blending ratio of 1% by weight of the solid content of the photosensitive solution, and a coating solution for forming an electrophotographic photosensitive layer was added. did.

Thereafter, an electrophotographic lithographic printing plate was produced in the same manner as in Example 3. Using the obtained electrophotographic printing plate, the printing background stain was evaluated in the same manner as in Example 3.

The results are shown in Table 1.

Comparison ■Soil The following composition: Zinc oxide (manufactured by Sakai Chemical Co., Ltd., 5AZf!X #2000)
90 parts polyacrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., LR-188) 25
A mixed solution consisting of 1 part rose bengal, 0.02 parts, and 120 parts toluene was dispersed with a sand grinder to obtain a photosensitive liquid.

Separately, the following composition: Zinc oxide (manufactured by Sakai Chemical Co., Ltd., 5AZEX 112000)
40 parts water
Mixed liquid consisting of 18.3 parts was mixed with 20 parts in a homomixer.
After dispersing for a minute, the mixture was dried and solidified at 100°C for 24 hours, and the solidified product was ground in a mortar, and the resulting particles were classified using a sieve to adjust the particle size to 20-60. This particle was not subjected to electron beam irradiation. Thereafter, an electrophotographic lithographic printing plate was obtained by the same operation as in Example 1. Using the obtained electrophotographic printing plate, the printing background stain was evaluated in the same manner as in Example 1. The results are shown in Table 1.

1 Comparison 1 The following composition: Zinc oxide (manufactured by Sakai Chemical Co., Ltd., 5AZEX 12000)
90 parts polyacrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., LR-188) 25
Part sensitizer (compound of -formation (If) above) 0.02
A mixed solution consisting of 120 parts of toluene was dispersed using a sand grinder to obtain a photosensitive liquid.

Separately, the following composition: Zinc oxide (manufactured by Sakai Chemical Co., Ltd., 5AZEX #2000)
Part 40 Part l Surface water 18
．． After dispersing the mixed solution consisting of 3 parts for 20 minutes in a homomixer, it was dried and solidified at 100°C for 24 hours, the solidified product was ground in a mortar, and the resulting particles were then classified with a sieve to give 20 to The particle size was adjusted to 60. The particles were not subjected to electron beam irradiation. Hereafter, coating was carried out in the same manner as in Example 3,
An electrophotographic printing plate was created.

Using the obtained electrophotographic printing plate, the printing background stain was evaluated in the same manner as in Example 3. The results are shown in Table 1.

(1) Plate making and printing without mechanical distortion.

(2) Evaluation of image quality (resolution, image reproducibility).

◎: Very good O: Good Δ: Slightly poor As Table 1 clearly shows, the electrophotographic photosensitive layers of Examples 1-4 according to the present invention were resistant to forced friction; Thereby, it is possible to obtain a printing plate material that does not or has less background smear during printing.

In Comparative Example 1.2, a protrusion is formed, but
Since the resin in the particles was not crosslinked by electron beam irradiation, the surface of the electrophotographic photosensitive layer was easily damaged by friction, and therefore, the invention of printing background staining was observed.

3...Zinc oxide secondary binding hard particles, 4... Protrusion.

〔Effect of the invention〕

In the lithographic printing plate material of the present invention, zinc oxide secondary binding hard particles coated and bound by a styrene-butadiene copolymer cross-linked and cured by electron beam irradiation are dispersed and contained in the electrophotographic photosensitive layer. By forming a large number of protrusions on the surface of the photosensitive layer, damage to the photosensitive layer due to friction can be prevented or suppressed, and there is no staining on the printing surface.
Alternatively, printed matter with excellent image quality can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing the structure of the lithographic printing plate material of the present invention. 1...Support, 2...Electrophotographic photosensitive layer,

Claims (1)

[Scope of Claims] 1. A conductive support having water resistance, an insulating resin binder formed on one surface of the support, and a large number of particles dispersed in the resin binder. an electrophotographic photosensitive layer containing photoconductive zinc oxide fine particles, and a large number of granules are further dispersed in the electrophotographic photosensitive layer, and the granules are used as the electrophotographic photosensitive layer. A large number of protrusions are formed on the surface, and the granules forming the protrusions are made of an electron beam-cured resin made of a styrene-butadiene copolymer that is cured by intermolecular crosslinking by electron beam irradiation, and this cured resin. Electrophotographic lithographic printing, characterized in that it is secondary bound zinc oxide hard particles consisting of a plurality of zinc oxide fine particle aggregates bound by a resin and having an average particle size of 20 to 60 μm. Plate material.