JPS6017759A - Printing plate for electrophotographic plate making - Google Patents

Abstract

PURPOSE:To directly make a printing plate through the electrophotographic process and to enhance printing resistance by forming a layer composed essentially of a specified azo pigment and an alkali-soluble resin on a conductive substrate. CONSTITUTION:A conductive substrate is coated with a layer composed essentially of an alkali-soluble resin and an azo pigment represented by the formula shown here in which A in a coupler residue. As the coupler of the formula, compds. having a phenolic OH group, such as phenols and naphthols, and an aromatic compds. having an amino group, etc. are used. As said alkali-soluble resin, a resin solubilized in an aq. or alcoholic solvent by addition of alkali, and, e.g. a styrene-maleic anhydride copolymer, a styrene-methacrylic acid-methacrylate copolymer, etc., are used, and for this resin, film forming property, electric characteristics, strength of adhesion to a substrate, and especially solubility characteristics, etc. are important. The printing plate of such a constitution is good in sensitivity and it can be directly manufactured by using various kinds of light sources, such as laser, and the obtained printing plate has high printing resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a novel printing plate that can be made by electrophotography. More specifically, with a new printing plate containing a specific azo pigment, an electrostatic latent image obtained by charging and subsequent image exposure is developed with toner and fixed to obtain a toner image, and then the non-image area is This invention relates to a printing plate that is made by dissolving and removing a photosensitive layer.

BACKGROUND ART Conventionally, as master plates for lithographic printing, those using photosensitive resins or silver halide photosensitive materials have been known.

However, although lithographic printing plates using photosensitive resin have high printing durability, they have low sensitivity, and so-called direct plate making is not possible, and it is necessary to create negatives or positives from the original using silver halide film. For this purpose, large-scale equipment is required, and there are drawbacks such as the time required for plate making.

Further, although printing 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.

Examples of printing plates for direct plate making using electrophotography include JP-B No. 47-47610 and JP-B No. 48-40.
002, Special Publication No. 48-18325, Special Publication No. 51-157
No. 66, Japanese Patent Publication No. 51-25761 discloses a zinc oxide-resin dispersion printing plate. After forming a toner image on this printing 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. The printing plate made in this way is protected against the mechanical pressure applied during printing and the photosensitive layer of the dampening solution.
Peeling occurs due to penetration into the conductive treatment layer and the hydrophilic layer on the surface is destroyed, so its printing durability is 5,000~I
It was about o, ooo pieces.

Further, zinc oxide/resin dispersion printing plates are subjected to dye sensitization in order to have sensitivity in the visible light region, but even so, they do not exhibit sensitivity sufficient for practical use in the long wavelength light region of 600 na+ or more. Therefore, the low-power and inexpensive 14e-N
The drawback is that exposure cannot be performed using an e-laser or a semiconductor laser.

Special Publication No. 37-17162, Special Publication No. 38-7758, Special Publication No. 46-39405, No. 52-2437, No. 5
In the organic photoconductive compound-resin printing plate described in Japanese Patent No. 6-107246, for example, an oxadiazole compound or an oxazole compound is bonded with an alkali-soluble resin such as a styrene-maleic anhydride copolymer. An electrophotographic photoreceptor is used in which a photographic photosensitive layer is provided on a grained aluminum plate. After a toner image is formed on this photoreceptor by electrophotography, the non-image area is dissolved and removed using an alkaline organic solvent. Make a plate.

Similar to zinc oxide-resin printing plates, such organic photoconductive compound-resin printing plates undergo dye sensitization to have sensitivity in the visible light region, but the sensitivity is lower than that of other electrophotographic photoreceptors. Compared to this, it is extremely unsatisfactory. Especially +3
It has almost no sensitivity to long-wavelength light of 00 nm or more, and image exposure cannot be performed using a l-18-Jle laser or a semiconductor laser.

Purpose The present inventors have conducted intensive research to solve the problems of the conventionally known printing plates for electrophotographic engraving as described above.
This has led to the completion of the present invention.

An object of the present invention is to provide a printing plate for electrophotolithography that has high sensitivity and provides a sharp image without staining in non-image areas.

Further, another object of the present invention is 1-18. - It is an object of the present invention to provide a printing plate for electrophotographic engraving that can be recorded with various light sources such as an N13 laser or a semiconductor laser.

Specifically, the present invention provides a layer containing an azo pigment represented by the following general formula and an alkali-soluble resin as main components on a conductive support (where A represents a coupler residue. 2 Here, examples of the coupler include compounds having a phenolic hydroxyl group such as phenols and naphthols, aromatic amino compounds having an amino group,
Aminonaphthols having an amine group and a phenolic hydroxyl group or a compound having an aliphatic or aromatic phenolic ketone group (active methylene group) are used, and preferably the coupler residue A has the following general formula (I), <II ),
It is selected from the group represented by (1v), (V), Vl), and (■).

[Wherein, R+ is hydrogen, an alkyl group, a phenyl group or a substituent thereof, X is a hydrocarbon ring or a substituent thereof, a heterocycle or a substituent thereof, Y is a hydrocarbon ring group or a substituent thereof, hetero Ring substituents, heterocyclic groups or their @
or a styryl group or a substituent thereof, R3 represents hydrogen, an alkyl group, a phenyl group, or a substituent thereof, or R2 and R3 form a ring with the carbon atom to which they are bonded and b. Good too. )] (R4 in formulas (I[) and (1v) represents a substituted or unsubstituted hydrocarbon group.) (In the formula, R5 represents an alkyl group, a carbamoyl group, a carboxyl group or an ester thereof, and (Ar+ represents a carbocyclic group or a substituent thereof.) (In the formula, R6 is a hydrocarbon group or a substituent thereof, Ar
2 represents a hydrocarbon ring group or a substituted product thereof. ) The hydrocarbon ring substituted for X in the general formula used in the present invention includes, for example, a benzene ring, a naphthalene ring, etc.
Examples of heterocycles include indole rings, carbazole rings, benzofuran rings, etc. Examples of hydrocarbon ring groups in Y or R2 include phenyl groups, naphthyl groups, anthryl groups, pyrenyl groups, etc. is a pyridyl group,
chenyl group, furyl group, indolyl group, benzofuranyl group, cartazolyl group, dibenzofuranyl group, etc., and R
Examples of the ring that can be formed by 2 J5 and R3 together with the carbon atoms to which they are bonded include a fluorene ring.

Furthermore, R4 and tc are hydrocarbon groups substituted by J5L in R6, such as alnitrol groups such as methyl, ethyl, propyl and butyl groups, aryl groups such as benzyl and 77ralkylenyl groups, or aryl groups thereof. Examples include substitution products. Substituents on the hydrocarbon group of R4 or R6 include methyl, ethyl, propyl, argyl groups such as ethyl groups, me-1-xy groups, 11-xy groups, propoxy groups, 11-xy groups. Examples include alkoxy groups such as chlorine atoms, halogen atoms such as bromine atoms, hydroxyl groups, and 21. A halogen atom may also be present in the carbocyclic or heterocyclic group of Y or R2 or in the ring formed by R2 and R3.
Examples of f-operating groups include alkylpoxy groups such as methyl, ethyl, propyl, and ethyl groups, alkoxy groups such as butoxy, chlorine atoms,
Halogen atoms such as bromine atoms, dimethylamino groups, sialyl-4nylamino groups such as dimethylamino groups, dialkylamino groups such as dibenzylamino groups, halomethyl groups such as trifulΔromedyl groups, di-l-ro groups, cyano groups, carboxyl group or its ester, hydroxyl group, sulfone M
group (SO3Na), etc. Furthermore, Arl.
Alternatively, the hydrocarbon ring group for Ar2 includes a phenyl group, a naphthyl group, etc., and the substituents for these groups include an alkyl group such as a methyl group, an ethyl group, a propyl group, an ethyl group, a me-1-xy group, Alkoxy groups such as xy groups, propoxy groups, butoxy groups, di]-ro groups, halogen atoms such as chlorine atoms and bromine atoms, cyan groups,
Examples include dimethylamino groups and dialkylamino groups such as dimethylamino groups.

The azo pigment used in the present invention is, for example, JP-A-57-
It is described in No. 46246. Examples of these Azo faces 1 are as follows.

Common parts in the general formula are omitted, and Δ is shown.

The alkali-soluble resin used in the present invention refers to a resin that becomes soluble in an aqueous or alcoholic solvent by adding an alkali. For the purpose of understanding wood, in addition to properties such as film-forming properties, electrical properties, and adhesion strength to a support, solubility properties are particularly important for these resins. Examples of resins having such characteristics include styrene-maleic anhydride copolymer, styrene-methacrylic acid-1 methacrylate copolymer, methacrylic acid-methacrylate 1 copolymer, and phenol resin. is exemplified. Examples of the phenolic resin include phenol, 0-cresol, m-cresol, p-taresol, ethylphenol, isopropylphenol, dobdelphenol, dooramylphenol, hexylphenol, ti-ctylphenol, cyclohexylphenol, 3- At least one substituted phenol such as methyl-4-chloro-6-tert-butylphenol, isopropyl-1-lucresol, [-butyl-cresol, door-amyl cresol, hexyl-cresol, cyclohexyl-cresol, and cyclohexyl-cresol, and formaldehyde, ace-1-aldehyde. ,
A novolac type resin obtained by condensing aldehydes such as acrolein, hemenaldehyde, and furfural with acidic treatment A'1 is used.

The printing plate of the present invention may contain an electron-accepting compound or an L-electron-sensitive compound, mainly for the purpose of improving electrophotographic properties such as sensitivity.

Examples of electron-accepting compounds include phthalic anhydride, dichlorophthalic anhydride, dichlorophthalic anhydride, biromellitic anhydride, mellitic anhydride, vicryl chloride, and 2,4-dichlorophthalic anhydride. Herochlorobenzene, 2.4-
dinit[lbromobenzene, 4-nitropift-nyl, 2
, 4.6-dolini-1 heroanisole, 4,6-dichloro-1,3-dinitrobengene, chloranil, tulomuanil, 2,4.7-l~lini-1 hero-9-fluylene,
2,4,5.7-titranitro-9-fur A-lenone,
tetracyanoethylene, tetracyanoquinone dimethane,
2,4,5.7 - Tetranitroxanthone, 2,4.8
-1-LinitrodiA xanthone, 2,6,8-trinitro-4to1-indeno[1,2-b ]]thiophene-4-'Ane1,3.7-1-Linitrodibenzothiophene-5,5 - Dioxide etc. are used.

Examples of electron-donating compounds include 2.5-bis(4
-diethylaminophenyl) -1,3,4-Jxadiazole, 2,5-bis[4-(4-diethylaminostyryl)phenyl] -1,3,4-oxadiazole, 2-(9-ethylcarbazolyl) -3-) -5-(4
-diethylaminophenyl) -1,3,4-, dxadiazole, etc. A4: Thadiazole compounds, 2-vinyl-4-(2-chlorophenyl)-5-(4-diethylamino)oxazole, 2-(4-diethylaminophenyl) )-4-Phenyloxazole and other oxazole compounds, 1-phenyl-3-(4-diethylaminostyryl)-5-(4-diethylaminophenyl)pyrazoline, 1-phenyl-3-(4-dimethylaminostyryl)-5- Pyrazoline compounds such as (4-dimethylaminophenyl)pyrazoline, 2,2'-dimethyl-4
, 4'-bis(diethylamino)triphenylmethane, 1,1-bis(4-dibenzylamylaminyl)propane, 1-lis(4-diethylaminophenyl)methane, 9-(4 Fluorene compounds such as -dimethylaminobenzylidene)norΔlene, 3-(9-furArenylidene)-9-ethylcarbazole, 9-(4-diethylaminostyryl)an1-
styryl anthracene compounds such as rasin, 9-bromo-10-(4-diethylaminostyryl) anthracene, 1,2-bis(4-diethylaminostyryl)benzene, 1,2-bis(2,4-thume-1-xystyryl) ) distyrylbenzene compounds such as benzene, 9-ethylcarbazole-3-aldehyde tomethyl-1-phenylhydrazone, 9-ethylcarbazole-3-aldehyde 1
-benzyl-1-phenylhydrazone, 4-diethylaminobenzaldehyde 1,1-diphenylhydrazone,
2.4-dimethoxybenzaldehyde 1-benzyl-1
- hydrazone compounds such as hydrazone, 4-diphenylaminobenzaldehyde 1-methyl-1-phenylhydrazone, stilbene compounds such as 4-diethylaminostilbene, 4-dibenzylaminostilbene, 4-di-1-lylaminostilbene, 1- Styrylnaphthalene compounds such as (4-diphenylaminostyryl)naphthalene, 1-(4-dibenzylaminostyryl)naphthalene, 4'-sifuenylamino-α-phenylstilbene, 4-methylphenylamino-α-phenylmethyl α-phenylstilbene compounds such as ben,
3-styryl-9-■ del-carbazole, 3-(4-
Styrylcarbazole compounds such as diethylamino)styryl-9-ethylcarbazole are used.

Furthermore, the printing plate of the present invention can contain a plasticizer. Examples of right-handed plasticizers include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, and dibutyl phthalate, and glycol esters such as dimethyl glycol phthalate and ethyl phthalyl ethyl glycole.

These plasticizers degrade the electrostatic properties and alkali solubility of the photoconductive Ti layer I! It can be contained within a certain range.

The conductive substrate C used in the present invention is an aluminum plate, a zinc plate, or a bimetal plate such as a copper-aluminum plate, a copper-stainless steel plate, a chromium-copper plate, or a chromium-copper plate.
Copper-aluminum plate, chromium-lead-iron plate, chromium-copper-
A conductive substrate with a hydrophilic surface such as a tri-metal plate such as a stainless steel plate is used, and its thickness is 0.1 to 1 m.
m is preferred.

In addition, especially in the case of a support having an aluminum surface, graining treatment, immersion treatment in an aqueous solution of silicon 1, 1 helium, fluorozirconate), phosphate, etc., or anodizing treatment, etc. Preferably, the material has been surface-treated. Also US Patent No. 27140613
As shown in JP-A-47-5125, an aluminum plate is grained and then immersed in an aqueous solution of sulfurium citric acid. It is also preferable to soak it in an aqueous solution of an acid salt.

The above-mentioned anodizing treatment is performed, for example, by treating aluminum in an electrolytic solution consisting of a solution of an inorganic acid such as phosphoric acid, chromic acid, sulfuric acid, or boric acid, or an organic acid such as oxalic acid or sulfamic acid, or a salt thereof. This is carried out by passing an electric current through the plate as an anode.

In addition, according to the present invention, if necessary, an alkali-soluble material such as casein, polyvinyl alcohol, ethyl cellulose, phenol resin, styrene-maleic anhydride copolymer, polyacrylic acid, etc. is added between the conductive substrate and the photoconductive layer. r! & layers can be applied to improve the adhesion between the substrate and the photoconductive layer or the electrostatic properties of the photoconductive layer.

The azo pigment used in the printing plate of the present invention only needs to be contained in the electrophotographic photosensitive layer together with an alkali-soluble resin and, if necessary, additives such as an electron-accepting compound or an electron-donating compound. Preferably, it is dispersed in the resin, and usually it is incorporated into the photosensitive layer by this method.

To produce the electrophotographic printing plate of the present invention, the pigment represented by the above general formula and an alkali-soluble resin may be used, for example, tetrahydrofuran, dioxane, dimethylformamide, acetone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Butyl acetate, ethyl acetate, [-luene, halogenated hydrocarbon, etc. are mixed in an organic solvent, and if necessary, an electron-accepting compound or an electron-donating compound is added thereto. A uniformly dispersed coating solution is prepared using a dispersion means, and the obtained coating solution is coated onto the conductive support, if necessary, via the above-mentioned intermediate layer, and dried.

The amount of the azo pigment and alkali-soluble resin that form the electrophotographic photosensitive layer of the printing plate of the present invention is preferably 0.01 to 100 parts by weight of the alkali-soluble resin per 1 part by weight of the azo pigment. When adding chemical compounds or electron-donating compounds, these should be added in an amount of 0.01 to the azo pigment.
-100 mol is preferable, and 0.01-40 mol is especially preferable. The thickness of the electrophotographic photosensitive layer on the iq conductive substrate is preferably 1 to 50 μm, particularly 1 to 15 μm.
m is preferred.

The printing plate for electrophotographic engraving of the present invention is uniformly charged in a dark place using a corona charger or the like in accordance with the conventional electrophotographic method, and using a light source such as a tungsten lamp, halogen lamp, xenon lamp, or fluorescent lamp. reflection image exposure, contact f11 exposure through a transparency film, or He
- Scanning exposure with laser light such as Ne laser, argon laser or semiconductor laser is performed to form an electrostatic latent image, and this electrostatic latent image is developed with toner and fixed by heat to form a toner image on the electrophotographic photosensitive layer. get.

Next, when the printing plate on which the toner image has been formed is immersed in an alkaline eluent, the photosensitive layer in the non-image area that is not masked by the toner image is dissolved and removed, and the hydrophilic surface of the conductive substrate is exposed. Only the exposed toner image portion remains on the surface of the support, and a good printing plate can be obtained.

The eluent used here is, for example, an alkaline aqueous solution of an inorganic salt such as sodium 11 silicate, sulfur phosphate, sulfur hydroxide, sulfur sulfur carbonate, or an organic amine such as triethanolamine or ethylenediamine. An alkaline aqueous solution or a solution prepared by adding an organic solvent such as ethanol, benzyl alcohol, ethylene glycol, or glycerin or a surfactant to these aqueous solutions are used.

In the printing plate of the present invention, after the toner image is formed, the non-image areas are dissolved and removed in the eluent, so the l-ner component contains a resin component having resist properties in the eluate. Preferably.

This resin component may be anything that is insoluble in the eluate, such as acrylic resin using methacrylic acid, methacrylic acid ester, vinyl acetate resin, copolymer of vinyl acetate and ethylene or vinyl chloride, etc. , vinyl chloride resin, vinylidene chloride resin, vinyl acecool resin such as polyvinyl butyral, polystyrene, copolymers of styrene and butadiene, methacrylic acid esters, poly-1-dylene, polyp-copylene and its chloride, polycarbon-1-, Examples include polyester resin, polyamide resin, phenolic resin, xylene resin, alkyd resin, wax, polyolefin, and wax.

The printing plate of the present invention may also contain a quinonediazide compound such as 0-naphthoquinonediazide or a diazo compound for the purpose of increasing the solubility of the electrophotographic photosensitive layer by exposure on the other side after toner image formation.

In the printing plate of the present invention, after the plate-making process is completed, the conductive substrate with a hydrophilic surface is exposed in the non-image area, and the image (ψ part) covered with the lipophilic toner remains. The oil-based ink adheres only to the image area, resulting in good printed matter without background stains.

Further, according to the present invention, it has high printing durability, high sensitivity, and dye reflex 1~! with various light sources such as laser light! The number of printing plates that can be made into one edition is 1q.

Furthermore, the photosensitive layer of the printing plate of the present invention can also be used for manufacturing printed wiring boards.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Azo compound I N 0.1 1 part by weight Styrene-maleic anhydride copolymer 1 bottle 5 parts by weight Te1-rahydrofuran 64 parts by weight The mixture having the above composition was thoroughly ground and mixed in a ball mill to obtain a dispersion. The liquid was poured onto a wire A7 plate with a thickness of about 0.25 mm and anodized aluminum plate.
A printing plate having an electrophotographic photosensitive layer having a film thickness of 6 μm was prepared by coating with a bar and drying at a temperature of 100° C. for 20 minutes.

This printing plate was positively charged by corona discharge of 16 kV for 10 seconds using an electrostatic copying paper testing device (manufactured by Sagi Yokuchden A Seisakusho, Model 5P-42, 8). vinegar,
11. Tungsten light. Exposure was made at Q IQ 20 Lux. As a result, the charging potential after 10 seconds is 507 volts]~
, the half-life exposure was 19 lux·sec.

Next, this printing plate was held at 111 places by electric discharge for about 4 hours.
After being charged to 1 to 00 pol, image exposure was carried out using a tungsten light source, development was carried out using a toner with an electrostatic latent (Φ of 1 to 1), and a toner image was formed by heating and fixing.

Next, the printing plate on which the toner image was formed was immersed in a 1% by weight 1-lium silicate aqueous solution, and then washed with a water jet while being lightly brushed to remove the electrophotographic photosensitive layer in the non-image area.

The printing plate made in this way is sold at Ricoh ¥ JA Press 1.
- When printing was carried out using a printing machine △p-1310 model according to a conventional method, 50,000 sheets of very clear prints without background smearing were printed.

Example 2 Azo pigment No. 4 1 part by weight n1-cresol formalkyd resin 5 parts by weight 2.5-bis(diethylaminophenyl) -1,3,4-J 4: Zadiazole 5
Part by weight: 1" tetrahydrofuran 99m 1 part ff A mixture having the above composition was thoroughly ground and mixed in a ball mill, and the resulting dispersion was sand-Hitachi C and anodized to a thickness of 0.
Coated on a 25mm aluminum plate and heated at 100℃ for 20 minutes.
The mixture was dried for minutes to produce a printing plate having an electrophotographic photosensitive layer with a thickness of 6 μm.

With respect to this printing plate, the charging potential and half-decrease exposure amount were measured in the same manner as in Example 1. As a result, the charging potential was +520 volts, and the half-decrease exposure amount was 7.8 lux·sec.

Next, this printing plate was charged in the same manner as in Example 1.

image@exposure, development, fixing] - form an image,
Furthermore, the electrophotographic photosensitive layer in the non-image area was removed.

Using the printing plate made in this way, printing was carried out in the same manner as in Example 1, and 50,000 very clear prints with no scuffing were printed after printing.

Example 3 7 SoJiJi No. 6 1fflffi parts Methyl methacrylate (80%) / methacrylic III (20%) copolymer 5 parts by weight 2 Hatake 7-Dolinitro 9-Fluorenone 5 parts by weight Tetrahydrofuran 99! The dispersion obtained by sufficiently pulverizing and mixing the mixture having the above composition using a ball mill was coated on a 0.25 mm thick aluminum plate that had been grained and ViJ polar oxidized.
A printing plate having an electrophotographic photosensitive layer having a thickness of 1 μm was prepared by drying at 00'C for 20 minutes.

The charging potential and half-decrease exposure amount of this printing plate were measured in the same manner as in Example 1 except that it was charged at -6.0 kV. As a result, the charging potential was reduced by half by 1617 volts and the exposure amount was 5.5
It was Lutx Sec.

Next, this printing plate was charged, image exposed, and exposed in the same manner as in Example 1.
Development and fixation were performed to form a 1-screen image, and the electrophotographic photosensitive layer of non-image 811 was removed.

This J, sea urchin'UT! When printing was carried out in the same manner as in Example 1 using a J-print printing plate, 50,000 clear prints with no blur were printed.

Effects As explained above, the present invention has good printing speed, allows die-reg plate making with various light sources such as laser light, and the resulting printing plate has high printing durability.

Special W [Applicant Rico Co., Ltd.] Agent: Attorney-at-Law Hidetake Komatsu Agent Patent Attorney Hiroshi Asahi -46'

Claims (1)

[Scope of Claims] (1) An electrophotographic process characterized in that a layer containing an azo pigment represented by the following general formula (I) and an alkali-soluble resin as main components is provided on a conductive support. Print version. 0) In the azo pigment represented by the general formula (I), A is the general formula (I) [wherein R1 is hydrogen, an alkyl group, a phenyl group or a substituted product thereof, X is a hydrocarbon ring or a substituted product thereof, Heterocycle or a substituent thereof, Y is a hydrocarbon ring group or a substituent thereof, or a substituent thereof, a heterocyclic group or a substituent thereof, or a styryl group or a substituent thereof, R3 is hydrogen, alkyl group, phenyl group, or a substituent thereof, or R2 and R3 may form a ring together with the carbon atom to which they are bonded. )] [The printing plate for electrophotolithography according to claim (1). (3) In the azo pigment represented by general formula (I), Δ
is the general formula (II) or lζ is (IV)U (R4 in formulas (I) and (IV) is substituted or unsubstituted W
represents a substituted hydrocarbon group. ) A printing plate for electrophotolithography according to claim (1). (4) In the azo pigment represented by the general formula (I), A represents the general formula (v) (wherein Rs represents an alkyl group, a carbamoyl group, a carboxyl group, or an ester thereof, and Ar+ represents a carbocyclic group or The printing plate for electrophotolithography according to claim (1), which represents a substituted product of. (9) In the azo pigment represented by the general formula (I), 8 is the general formula (Vl) or (■1) (wherein, R6 is a hydrocarbon group or a substituent thereof, Ar
z represents a hydrocarbon ring group or its H radical -0)
A printing plate for electrophotolithography according to claim (1).