JPH0222094A - Desensitizing treatment of planographic printing plate - Google Patents

Abstract

PURPOSE:To densitize a non-image part and to protect a plate surface by treating a planographic printing plate with an emulsion type plate surface protective agent consisting of an aqueous phase containing a hydrophilic high- molecular compound and an oil phase containing a specific surfactant. CONSTITUTION:An emulsion type plate surface protective agent is prepared by compounding an aqueous phase having a hydrophilic high-molecular compound dissolved and contained therein with an oil phase containing an alkylphenyl type nonionic surfactant having an HLB value of 14 or less and an anionic surfactant. A planographic printing plate, wherein an image part is composed of the toner image formed on the photoconductor layer provided on a conductive substrate by an electrophotographic process and a non-image part is the conductive substrate, is treated with the aforementioned prepared emulsion type plate surface protective agent to perform the densensitizing treatment of the planographic printing plate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for desensitizing a lithographic printing plate formed by an electrophotographic process.

[Conventional technology]

Today, as lithographic offset printing plates, PS plates that use positive-working photosensitizers whose main components are diazo compounds and phenolic resins, and negative-working photosensitizers whose main components are acrylic monomers and prepolymers are in practical use. However, all of these have low sensitivity, so plate making is performed by contact exposure of a silver halide photographic film master plate on which an image has been recorded in advance. on the other hand,
Advances in computer image processing, large-capacity data storage, and data communication technology have meant that in recent years, everything from manual input, correction, editing, and page layout to page layout has become computer-controlled, and high-speed communications networks and satellite communications have enabled instant delivery to remote locations. Electronic editing systems that can output to terminal plotters have been put into practical use. In particular, electronic editing systems are in high demand in the field of newspaper printing, which requires immediacy. Furthermore, even in fields where originals are preserved in the form of original film, and printing plates are reproduced as needed based on this, with the development of ultra-high capacity recording media such as optical discs, the originals are being stored on these recording media. It is thought that it will be stored as digital data.

However, direct printing plates that create printing plates directly from the output of terminal plotters have hardly been put into practical use.
Even in places where electronic editing systems are in operation, the current situation is that output is performed on silver halide photographic film, and based on this, printing plates are indirectly created by contact exposure to PS plates. This is the light source of the output probe (e.g. He-N
This means that it is difficult to develop a direct printing plate with a sensitivity high enough to make a printing plate within a practical time using a semiconductor laser (e.g., semiconductor laser).

Electrophotographic photoreceptors are considered as photoreceptors with high photosensitivity that can provide direct printing plates.

Conventionally, printing plate materials (printing original plates) using electrophotography include, for example, Japanese Patent Publication No. 47i7610, Japanese Patent Publication No. 48-
No. 40002, Special Publication No. 18325, Special Publication No. 18325, Special Publication No. 1971
Zinc oxide-resin dispersion offset printing plate materials described in Japanese Patent Publication No. 15766 and Japanese Patent Publication No. 51-25761 are known, and after forming a toner image by electrophotography, the non-image area is rendered oil-insensitive. For this purpose, it is used after being moistened with a desensitizing solution (for example, a ferricyan salt or an acidic aqueous solution containing a ferricyan salt). Offset printing plates treated in this way have a printing durability of about 5,000 to 10,000 sheets, and are not suitable for printing beyond this, and if the composition is made suitable for desensitization, the electrostatic properties deteriorate. However, there are drawbacks such as deterioration of image quality. It also has the disadvantage of using harmful cyanide compounds as desensitizing solutions.

Special Publication No. 37-17162, Special Publication No. 38-7758,
In the organic photoconductor-resin printing plate materials described in Japanese Patent Publication No. 46-39405 and Japanese Patent Publication No. 52-2437, for example, oxazole or oxadiazole compounds are combined with a styrene-maleic anhydride copolymer. An electrophotographic photoreceptor is used in which a photoconductive insulating layer is formed on a grained aluminum plate, and after a toner image is formed on this photoreceptor by electrophotography, the non-image area is dissolved with an alkaline organic solvent. It is removed (etched) to form a printing plate.

Further, JP-A-57-147656 discloses an electrophotographic photoreceptor containing a hydrazone compound and barbylic acid or thiobarbylic acid.

In addition, JP-A-59-147335, JP-A-591
No. 52456, JP-A-59-168462, JP-A-5
Dye-sensitized electrophotographic photoreceptors described in No. 8145495 and the like are known. However, substances in the electrophotographic photosensitive layer are adsorbed to the non-image areas of printing plates made using the above electrophotographic photoreceptor and contaminate the non-image areas, resulting in ink adhering to the non-image areas of printed matter. There was a problem in that it became unusable as a printing plate due to the occurrence of "stains".

On the other hand, when making a lithographic printing plate, a plate surface protective agent (so-called gum liquid) is applied in the final step.

The purpose of applying gum liquid is not only to protect the hydrophilicity of non-image areas, but also to modify images such as adding or erasing image areas, to preserve the image until it is printed on a plate-making machine or until it is reused, and to preserve it until it is installed on a printing machine. This is to prevent stains caused by the adhesion of fingerprints, oil, fat, dust, etc. during handling and handling, and to protect against scratches, etc., and also to suppress the generation of oxidation stains. Conventionally, gum arabic, cellulose gum, or an aqueous solution of a water-soluble polymeric substance having a carboxyl group in the molecule has been used as a gum solution for lithographic printing plates. However, when a large amount of organic staining substances adhere to these gum liquids, their desensitizing ability is poor and they become stained.

When stains occur due to the above causes, a step is required to remove organic stains, and stain removal liquids used for this purpose are also commercially available (for example, Plate Cleaner CO-3 manufactured by Fuji Photo Film ■).

However, the addition of such a step is not preferred due to the problem of reduced workability.

Furthermore, these gum liquids tend to cause water-soluble polymer substances to adhere to the image area, thereby reducing the oil sensitivity of the image area.

[Problems to be Solved by the Invention] Therefore, the purpose of the present invention is to remove stain-causing substances from a lithographic printing plate formed by an electrophotographic process, at the same time desensitize non-image areas, and further protect the plate surface. An object of the present invention is to provide a method for desensitizing a lithographic printing plate, which is useful for this purpose.

A further object of the present invention is to provide a method for desensitizing a lithographic printing plate formed by an electrophotographic process using a plate protective agent that does not reduce the oil sensitivity of the image area.

[Means to solve the problem]

The above purpose is to use a lithographic printing plate in which the image area consists of a toner image formed by an electrophotographic process on a photoconductor layer provided on a conductive substrate, and the non-image area is a conductive substrate. An emulsified plate surface protectant consisting of an aqueous phase containing a dissolved molecular compound, an organic solvent, an alkylphenyl type nonionic surfactant with an HLB of 14 or less, and an anionic surfactant. It has been found that this can be achieved by a method for desensitizing a lithographic printing plate, which is characterized by a process of desensitizing a lithographic printing plate.

HLB, the most characteristic component used in the present invention, is 1
4 or less alkylphenyl type nonionic surfactant,
Anionic surfactants will be explained.

The alkylphenyl type nonionic surfactant having an HLB of 14 or less is preferably a compound represented by the following general formula (I) and having an HLB of 14 or less.

In the formula, R represents an alkyl group, p represents 1 or 2, m represents an integer of 1 to 4, and n represents an integer of 2 or more.

) The alkyl group of R is preferably selected from alkyl groups having 8 to 18 carbon atoms, and specifically, octyl group, nonyl group, decyl group, undecyl group, dodecyl group (lauryl group)
, a tetradecyl group, a hexadecyl group (cetyl group), and the most preferred are an octyl group and a nonyl group. Also, the substitution position of R is 10(-(C12)□-0+
. The para-position to the H group is mainly used, but the meta- or ortho-position may also be used, and the p
is preferably 1, and m is preferably 2. Further, n varies depending on the type of alkyl group of R, but may be in a range such that the HLB value is 14 or less, and more preferably in a range of 4 to 12. A desensitizing agent using an agent having an HLB greater than 14 has the disadvantage of reducing the oil sensitivity of the image area of a lithographic printing plate.

Specific examples of such alkylphenyl type nonionic surfactants having an HLB of 14 or less include polyoxymethylene octylphenyl ether, polyoxymethylene nonylphenyl ether, polyoxymethylene cetyl phenyl ether, and polyoxymethylene lauryl having an HLB of 14 or less. Phenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene nonylphenyl ether,
Polyoquine ethylene decyl phenyl ether, polyoquine ethylene lauryl phenyl ether, polyoxypropylene octylphenyl ether, polyoquine propylene nonylphenyl ether, holioquine propylene decyl phenyl ether, polyoxypropylene lauryl phenyl ether, polyoxypropylene cetyl phenyl ether, polyol Quince butylene octylphenyl ether, polyoxybutylene nonylphenyl ether, polyoxybutylene denlphenyl ether, polyoxybutylene lauryl phenyl ether, polyoxybutylene cetyl phenyl ether, polyoxyethylene dinonylphenyl ether, etc. I can do it. Particularly suitable for the present invention are polyoxyethylene-based ones, and polyoxymethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, and the like are particularly preferably used.

On the other hand, the anionic surfactant, which is another characteristic component used in the present invention, includes, for example, fatty acid salts,
Anionic surfactants such as alkyl sulfate ester salts, alkylbenzene sulfonate salts, alkylnaphthalene sulfonate salts, dialkyl sulfosuccinate ester salts, alkyl phosphate ester salts, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl sulfate ester salts, etc. Included, but with particularly favorable results are dialkyl sulfosuccinates. The alkyl group of the dialkyl sulfosuccinates preferably has 2 to 18 carbon atoms, such as 5ec-butyl group, t-butyl group, hexyl group, 2-ethylhexyl group, nonyl group, decyl group. , dodecyl group, etc. are preferred. Specific dialkylsulfosuccinates include sodium diakylsulfosuccinate, sodium cy(2-ethylhexyl)sulfosuccinate, sodium dinonylsulfosuccinate, sodium dilaurylsulfosuccinate, and the like.

A plate protective agent containing a combination of an alkylphenyl type nonionic surfactant and an anionic surfactant does not reduce the oil sensitivity of the image area more than a plate protective agent containing each surfactant alone. The amount of each of these activators used is about 0.5 to about 10% by weight based on the total weight of the plate surface protectant.
, more preferably in a range of 1 to 5% by weight. Further, the ratio of the alkylphenyl type nonionic surfactant to the anionic surfactant is 10°1 to 1:10 by weight,
More preferably, it is in the range of 521 to 1.5.

The above two types of surfactants are dissolved in an organic solvent to constitute the oil phase of the plate surface protection agent of the present invention. Preferred organic solvents are water-insoluble, such as turpentine, xylene,
Toluene, n-hebutane, solvent naphtha, kerosene, mineral spirit, boiling point approximately 120° to approximately 250°C
Hydrocarbons such as petroleum fractions such as dibutyl phthalate, didecyl phthalate, di-n-octyl phthalate, di(2-ethylhexyl) phthalate, dinonyl phthalate, didecyl phthalate, dilauryl phthalate,
Phthalic acid diesters such as butylbenzyl phthalate, such as dioctyl adipate, butyl glycol adipate, dioctyl azelate, dibutyl sebacate,
Aliphatic dibasic acid esters such as di(2-ethylhexyl) sebacate and dioctyl sebacate; epoxidized triglycerides such as epoxidized soybean oil, such as tricresyl phosphate, trioctyl phosphate, trischlorethyl phosphate; Plasticizers include phosphoric acid esters such as benzoic acid esters such as benzoic acid pencil, etc., which have a freezing point of 15° C. or lower and a boiling point of 300° C. or higher at 1 atmosphere.

In addition, together with these solvents, for example, ketones such as cyclohexanone, halogenated hydrocarbons such as ethylene dichloride, ethylene glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monophenyl ether, and ethylene glycol monobutyl ether are used. Can be used together.

These solvents should be added in an amount of about 0.1% based on the total weight of the plate protectant.
~10% by weight, more preferably 15-5% by weight.

It is preferable that the oil phase further contains a lipophilic substance dissolved therein. As a result, the stability of the plate surface protective agent used in the present invention as an emulsion is further improved, and the decrease in oil sensitivity of the image area can be further reduced. Preferred lipophilic substances include lipophilic resins used as vehicles for lithographic printing plate inks. Specifically, novolak type phenol resins such as phenol formaldehyde resin, cresol formaldehyde resin, and t-butylphenol formaldehyde resin, xylene resins made by condensing phenol and xylene with formaldehyde, resins made by condensing phenol and mesitylene with formaldehyde, and polyester resins. Hydroquinone styrene, brominated polyhydroxystyrene, cashew resin, partially esterified copolymer of styrene and maleic anhydride, melamine resin, alkyd resin, polyester resin, epoxy resin, rosin, such as hydrogenated rosin, rosin ester, etc. Examples include modified rosins such as petroleum resins such as Giltonite,
Among these, novolac type phenolic resin, rosin and modified rosin are preferred.

Other preferred lipophilic substances include organic carboxylic acids having 5 to 25 carbon atoms, such as oleic acid, lauric acid, valeric acid, nonylic acid, capric acid, mystylic acid, palmitic acid, castor oil, and the like.

These lipophilic substances can be used alone or in combination of two or more, and are approximately 0.0% based on the total weight of the plate surface protectant.
It can be used in a range of 0.05 to about 5% by weight, more preferably 0.1 to 1% by weight.

On the other hand, the water-soluble polymer compound contained in the aqueous phase of the plate surface protective agent used in the present invention is a component that protects the non-image areas of the lithographic printing plate, and is preferably a water-soluble resin capable of forming a film.

Modified starches such as dextrins, gum arabic, starches and carboxyalkylated starches; alginates such as sodium alginate; water-soluble celluloses such as carboxyl methylcellulose, hydroquine ethyl cellulose, methyl cellulose; Examples include polyacrylamide, a water-soluble polymer containing an acrylamide unit, a copolymer of vinyl methyl ether and maleic anhydride, and a copolymer of vinyl acetate and maleic anhydride. Among these, particularly preferred are gum arabic, dextrin, polyvinylpyrrolitone, carboxymethylcellulose, and polyvinyl alcohol, and gum arabic is most preferred. These water-soluble polymer compounds can be used alone or in combination of two or more. In particular, it is preferable to use dextrin together with gum arabic because the hydrophilicity of the non-image area can be increased without reducing the oil sensitivity of the image area. The water-soluble polymer compound may be contained in the aqueous phase in a wide range of concentrations, but - for boat fishing, it may be present in an amount of about 5 to about 40% by weight, more preferably 10 to 30% by weight based on the total weight of the plate protectant. The concentration in the aqueous phase is from about 6 to about 60
% by weight, preferably 15-50% by weight.

Preferably, the aqueous phase further contains a wetting agent.

As a result, the aqueous phase of the plate surface protective agent used in the present invention can be imparted with the property of appropriately spreading to the non-image area of the lithographic printing plate.

Preferred such wetting agents are polyhydric alcohols, and preferred specific examples include ethylene glycone diethylene glycol, triethylene glycol, propylene glyconopebutylene glyconopepentane diol, hexylene glycol, tetraethylene glycol,
Polyethylene glycone vegetable propylene glycone
Examples include tripropylene glycol, glycerin, sorbitol, and pentaerythritol, with glycerin being particularly preferred. The dampening agent can be used in an amount of about 0.5 to about 10% by weight, more preferably 1 to 5% by weight, based on the total weight of the plate protective agent of the present invention.

Preferably, the aqueous phase further contains a water-soluble salt. This makes the non-image area more hydrophilic when the plate surface protectant is applied to the lithographic printing plate according to the present invention. Suitable water-soluble salts include alkali metal salts and ammonium salts, and those that give particularly good results include water-soluble alkali metal salts of acids such as acetic acid, molybdic acid, boric acid, nitric acid, sulfuric acid, phosphoric acid and polyphosphoric acid. Includes salts and ammonium salts. Specifically, ammonium acetate, sodium acetate, potassium acetate, sodium molybdate, potassium molybdate, sodium borate, ammonium borate, lithium nitrate, sodium nitrate, potassium nitrate, monobasic sodium phosphate, dibasic sodium phosphate, tribasic sodium phosphate, 1st
Potassium phosphate, dibasic potassium phosphate, tribasic potassium phosphate,
Examples include tertiary ammonium phosphate and sodium polyphosphate. Among the above, particularly preferred are potassium acetate, sodium borate, ammonium borate, potassium nitrate,
These are sodium molybdate, potassium molybdate, and potassium sulfate. Such water-soluble salts can be used alone or in combination of two or more, and are about 0.05 to about 2% by weight, more preferably 0.1% by weight based on the total weight of the plate surface protectant.
It is used in a range of 1% by weight.

When the water-soluble polymer compound dissolved and contained in the aqueous phase is gum arabic, the pH of the aqueous phase is in the acidic range,
More preferably it is adjusted to 1-5, most preferably 1-3. Therefore, if the pH of the aqueous phase is not acidic, more acid is added to the aqueous phase.

Examples of acids that can be added as pH adjusters include mineral acids such as phosphoric acid, sulfuric acid, and nitric acid; organic acids such as citric acid, phosphoric acid, malic acid, glacial acetic acid, emulsifying acid, oxalic acid, and p-)luenesulfonic acid; An example is acid. Among these, phosphoric acid is
It is particularly excellent because it not only functions as a pH adjuster but also has the effect of preventing stains in non-image areas, and is preferably 0.1 to 8% by weight, most preferably 0.5 to 8% by weight based on the total weight of the aqueous phase.
It is preferable to contain it in a range of 5% by weight.

Next, a typical manufacturing method of the plate surface protective agent used in the present invention will be explained.

First, a water-soluble polymer compound is dissolved in water to prepare an aqueous phase. If the aqueous phase further contains a wetting agent, water-soluble salt and/or acid, these are also added and dissolved.

Meanwhile, an oil phase is prepared by dissolving a surfactant in an organic solvent. If the oil phase further contains a lipophilic substance, this should also be added.

The oil phase thus obtained is dropped into the aqueous phase while stirring, and the resulting mixture is further emulsified using a homogenizer to obtain the plate protection agent according to the present invention.

Furthermore, we will explain how to use the printing plate protectant used in the present invention.

An appropriate amount of the plate surface protective agent used in the present invention is poured onto the etched lithographic printing plate prepared by the electrophotographic process described below, rubbed with a sponge so as to cover the entire surface of the plate, and then dried. A similar purpose can also be achieved by a commercially available gum coater that automates this process. This removes stain-causing substances on the printing plate, makes the non-image area desensitized, and further protects the printing plate.

When starting printing, generally the gum on the plate surface is washed with water (so-called gum removal), and then printing may be carried out according to the usual procedure, or the desensitizing liquid used in the present invention may be washed with water to remove the gum. You can also start printing immediately without dropping the printer.

When the plate surface protectant according to the present invention is used, the oil sensitivity of the image area of the lithographic printing plate is not reduced, while the hydrophilicity of the non-image area can be increased.

The present invention will be explained in more detail below.

Conductive substrates used in electrophotographic photoreceptors include plastic sheets with conductive surfaces or papers made particularly solvent-impermeable and conductive, aluminum plates, zinc plates,
Or has a hydrophilic surface such as a bimetallic plate such as a copper-aluminum plate, a copper-stainless steel plate, a chrome-copper plate, or a tri-metallic plate such as a chromium-copper-aluminum plate, a chrome-lead-iron plate, a chromium-copper-stainless steel plate, etc. A conductive substrate is used, and its thickness is preferably 0.1 to 3 mm, particularly preferably 0.1 to 0.5 mm. Among these substrates, aluminum plates are preferably used. The aluminum plate used in the present invention is a plate-shaped body such as pure aluminum whose main component is aluminum or an aluminum alloy containing a small amount of foreign atoms, and its composition is not specified, and publicly known and publicly used materials are used as appropriate. You can.

This aluminum plate can be used after being grained and anodized using a known method. Prior to the graining treatment, in order to remove rolling fat from the surface of the aluminum plate, degreasing treatment with a surfactant or an alkaline aqueous solution is performed, if desired, and then the graining treatment is performed. Graining treatment methods include a method of mechanically roughening the surface, a method of electrochemically dissolving the surface, and a method of selectively dissolving the surface chemically. As a method for mechanically roughening the surface, known methods such as ball polishing, brush polishing, blast polishing, buff polishing, etc. can be used. Further, as an electrochemical surface roughening method, there is a method in which alternating current or direct current is used in a hydrochloric acid or nitric acid electrolyte. Furthermore, a method combining both methods can also be used, as disclosed in Japanese Patent Application Laid-Open No. 54-63.902.

The aluminum plate thus roughened is subjected to alkali etching treatment and neutralization treatment as required.

The aluminum plate thus treated is anodized. As the electrolyte used in the anodizing treatment, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixed acid thereof is used, and the electrolyte and its concentration are determined as appropriate depending on the type of electrolyte. Since the treatment conditions for anodizing vary depending on the electrolyte used, it cannot be generally specified, but for boat fishing, the electrolyte concentration is 1 to 80% by weight, and the liquid temperature is 5 to 70%.
°C, current density 5 to 60 A/dm2, voltage 1 to 100 V,
It is preferable that the electrolysis time is in the range of 10 seconds to 50 minutes. The amount of anodic oxide film is preferably 0.1 to 10 g/m2, but
More preferably, it is in the range of 1 to 6 g/m2.

A known electrophotographic photosensitive layer (photoconductive layer) is provided on the conductive substrate thus obtained to obtain an electrophotographic photoreceptor.

As the photoconductive material used in the photoconductive layer, many conventionally known organic or inorganic compounds can be used. For example, known dispersible photoconductive materials include inorganic photoconductive materials such as selenium, selenium-tellurium, cadmium sulfide, zinc oxide, and the like. In addition, organic photoconductive compounds include 1) triazole derivatives described in U.S. Patent No. 3,112,197, etc., 2) triazole derivatives described in U.S. Patent No. 3,189,447, etc. 3) Imidazole derivatives described in Japanese Patent Publication No. 3'1-16,096, etc., 4) U.S. Pat.
．． No. 989, No. 3.542.544, Special Publication No. 1973-5
No. 55, No. 51-10, No. 983, JP-A No. 51-93.
No. 224, No. 55-108.667, No. 55-156
5) Polyarylalkane derivatives described in U.S. Patent No. 3.180.729, U.S. Pat. No. 064, No. 55-88.065, No. 49105, No. 537, No. 55-5L No. 086, No. 5
No. 6-80.051, No. 56-88.141, No. 57
-45,545, 54-112.637, 55
Pyrazoline derivatives and pyrazolone derivatives described in -74.546 specification, gazettes, etc., 6) U.S. Patent Box No. 3.615.404, Japanese Patent Publication No. 1983-10.105, No. 46-3,712, 47-28.336, JP-A No. 5483, 435, JP-A No. 54-110.836,
Phenyldiamine derivatives described in the specification of No. 54-119925, gazettes, etc. 7) U.S. Pat.
．． No. 703, No. 3.240.597, No. 3.658.
No. 520, No. 4.232103, No. 4.175.96
No. 1, No. 4.012.376, West German Patent (DA
S) No. 1.110.518, Special Publication 1977-35.7
No. 02, No. 39-27.577, JP-A-55-144
．． No. 250, No. 56119, No. 132, No. 56-22.
8) Amine-substituted chalcone derivatives described in U.S. Patent No. 3,526,501, 9) U.S. Patent No. 3,542,546, etc. 10) Oxazole derivatives described in U.S. Pat. 12) Fluorenone derivatives described in JP-A-54-110.837, etc., 13) U.S. Patent No. 3.717.462, JP-A-54-
No. 59143 (corresponding to U.S. Patent No. 4.150.987), No. 5552,063, No. 55-52.064,
No. 55-46.760, No. 55-85.495, No. 5711350, No. 57-148.749, No. 57
Hydrazone derivatives described in -104.144 specifications, publications, etc. 14) U.S. Pat.
．． No. 949, No. 4.265.990, No. 4.273.
No. 846, No. 4.299.897, No. 4.306.0
Benzidine derivatives described in JP-A-58-190.953 and JP-A-59-95.
No. 540, No. 59-97.148, No. 59-195.
Examples include stilbene derivatives described in JP-A No. 658 and JP-A No. 62-36.674.

In addition to the low-molecular photoconductive compounds mentioned above, the following high-molecular compounds can also be used.

16) Polyvinyl carbazole and its derivatives described in Japanese Patent Publication No. 1974-10.966, 17) Japanese Patent Publication No. 18674-1974, No. 43-19.19
Nohinyl polymers such as polyvinylpyrene, polyvinylanthracene, poly-2-vinyl-4-(4'-dimethylaminophenyl)-5-phenyloxazole, and poly-3vinyl-N-ethylcarbazole described in Publication No. 2, 18) Special 19) Polymers such as polyacenaphthylene, polyindene, and copolymers of acenaphthylene and styrene described in Publication No. 4:3-19.193; 19) Pyrene formaldehyde resins described in Japanese Patent Publication No. 13940/1982; Condensation resins such as frompyrene-formaldehyde'N resin and ethylcarbazole-formaldehyde resin, 20) JP-A-56-90.883, JP-A-56-161□
In addition to the various triphenylmethane polymers described in Publication No. 550, various pigments, dyes, etc. can be used for purposes such as improving the sensitivity of the photoconductor and giving it a desired photosensitive wavelength range. I can do it. Examples of these include: 1) U.S. Patent Nos. 4.436.800 and 4.439;
．． No. 506, JP-A-47-37543, JP-A No. 58-12
3.541, 58192, 042, 5L-21
No. 9,263, No. 5'J-78,356, No. 60-1
No. 79.746, No. 61-148.453, No. 612
38, No. 063, Special Publication No. 60-5941, No. 6 (1-
Monoazo, bisazo, and trisazo pigments described in U.S. Pat. No. 45,664, etc.; 2) U.S. Pat.
, 3) Perylene pigments as described in U.S. Patent No. 3.371.884, etc., 4) British Patent No. 2.237.68f1, etc. Indigo and thioindigo derivatives as described, 5) Quinacridone pigments as described in British Patent No. 2.237.679, etc., 6) British Patent No. 2.237.678, JP-A-59-
184.348, 62-28.738, etc., 7) Bisbenzimidazole pigments described in JP-A-47-30.331, etc., 8) U.S. Patent No. 4. No. 396.610, No. 4.644
．． Squarium ring pigments described in JP-A-59-53,850 and JP-A-61-212.
The azulenium salt pigment described in No. 542, etc. Also, as a sensitizing agent, "Sensitizer", p. 125, Kodansha 8
(19B?), “Electronic Photography J 12 9 (1973
) rOrganic Synthetic Chemistry J24 No, 11 1010
(1966) and the like can be used. For example, 10) U.S. Pat. No. 3.14L 770
No. 4.283.475, Special Publication Show 4g-25,65
8, JP-A No. 62-71.965, etc., pyrillam dyes, 11) ApH1ied Optics Sup
plement 3 50 (1969), triarylmethane dyes described in JP-A-50-39.548, etc., 12) cyanine-based dyes described in U.S. Pat. No. 3,597.196, etc., 13) JP-A-Sho No. 60-1'63047, No. 59-164
．． The styryl dyes described in No. 588 and No. 60-252.517, etc., and these organic photoconductive materials may be used alone or in combination.
More than one species may be used in combination.

For the purpose of improving sensitivity, the photoconductive layer of the present invention may contain electron-withdrawing compounds such as trinitrofluorenone, chloranil, tetracyanoethylene, etc.
．． No. 439, No. 58-102.239, No. 58-12
Examples include compounds described in No. 9.439, No. 62-7L 965, and the like.

In a photoreceptor for electrophotographic engraving, the photoconductive compound itself may have film properties, but if the photoconductive compound does not have film properties, a binding resin can be used. As the binding resin, resins known in the field of electrophotography can be used. In order to create a printing plate using an electrophotographic photoreceptor, it is necessary to finally remove the photoconductive layer in the non-image area, but this process is difficult due to the solubility of the photoconductive layer in the etching solution or This is determined by the relative relationship between the toner image and the etching solution, such as its resistivity.
I can't generalize. The binding resin is preferably a polymer compound that is soluble or dispersible in the etching solution described below.

Specifically, for example, a copolymer of styrene and maleic anhydride, a copolymer of styrene and monoalkyl maleic anhydride, a methacrylic acid/methacrylic acid ester copolymer, a styrene/nuccrylic acid/methacrylic acid ester copolymer, Acrylic acid esters such as acrylic acid/methacrylic acid ester copolymer, styrene/acrylic acid/methacrylic acid ester copolymer, vinyl acetate/crotonic acid ester copolymer, vinyl acetate/crotonic acid/meccrylic acid ester copolymer, etc. , methacrylic acid esters, styrene, vinyl acetate, etc., and copolymers with carboxylic acid-containing monomers or acid anhydride group-containing monomers such as acrylic acid, methacrylic acid, iconic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, etc. and methacrylic acid amide, vinylpyrrolidone, copolymers containing monomers with phenolic hydroxyl groups, sulfonic acid groups, sulfonamide groups, and sulfonimide groups, phenolic resins, partially saponified vinyl acetate resins, xylene resins, polyvinyl butyral Examples include vinyl acecool resins such as

A copolymer containing a monomer having an acid anhydride group or a carboxylic acid group as a copolymerization component, and a phenol resin have a high charge retention ability of the photoconductive layer when used as a photoreceptor for electrophotographic engraving, resulting in good results. It can be used with.

As the copolymer containing a monomer having an acid anhydride group as a copolymerization component, a copolymer of styrene and maleic anhydride is preferable. Half esters of this copolymer can also be used.

As a copolymer containing a monomer having a carboxylic acid group as a copolymerization component, a copolymer of two or more elements of acrylic acid or methacrylic acid and an alkyl ester, aryl ester or aralkyl ester of acrylic acid or methacrylic acid is used. preferable. Further, preferable examples include a copolymer of vinyl acetate and crotonic acid, and a terpolymer of vinyl acetate, a vinyl ester of a carboxylic acid having 2 to 18 carbon atoms, and crotonic acid. Among the phenolic resins, particularly preferred are phenolic resins such as phenolic resins such as phenolic resins, phenolic resins,
Examples include novolak resins obtained by condensing cresonope or p-fresol with formaldehyde or acetaldehyde under acidic conditions. The binding resin may be used alone or in combination of two or more.

When using a photoconductive compound and a binding resin, the content of the photoconductive compound is small, and the sensitivity decreases. , more preferably in an amount of 0.1 part by weight or more. Furthermore, if the photoconductive layer is too thin, it will not be able to charge the charge necessary for development, and if it is too thick, etching in the plane direction called side etching will occur, making it impossible to obtain a good image. It can be used in a range of 1 to 30μ, more preferably 0.5 to 10μ.

The electrophotographic printing plate of the present invention can be obtained by coating a photoconductive layer on a conductive substrate according to a conventional method. When creating a photoconductive layer, the components constituting the photoconductive layer can be contained in the same layer, or they can be contained separately in two or more layers, for example, by using different charge carrier generating substances and charge carrier transporting substances. There are known methods for separating the layer into layers, and it can be produced by any of these methods. The coating solution is prepared by dissolving each component constituting the photoconductive layer in an appropriate solvent, but when using components that are insoluble in solvents such as pigments, a dispersing machine such as a ball mill, paint shaker, Dyno Mill, or Attritor is used. Depending on the particle size, 5 μ to 0.1 μ
It is used by dispersing it into The binding resin and other additives used in the photoconductive layer can be added during or after dispersing the pigment. The coating solution prepared in this manner is coated onto a substrate by a known method such as spin coating, blade coating, knife coating, reverse roll coating, dip coating, rod bar coating, or spray coating and is dried to form a printing plate for electrophotolithography. can be obtained. Solvents for preparing the coating solution include halogenated hydrocarbons such as dichloromethane, dichloroethane, and chloroform, alcohols such as methanol and ethanol, ketones such as acetone, methyl ethyl ketone, and nclohexanone, and ethylene glycol monomethyl ether. Examples include glycol ethers such as methoxyethyl acetate, ethers such as tetrahydrofuran and dioxane, and esters such as ethyl acetate and butyl acetate.

In addition to the photoconductive compound and the binding resin, the photoconductive layer may contain plasticizers, surfactants, and other additives as necessary to improve the film properties such as flexibility and coating surface condition of the photoconductive layer. agent can be added. Examples of the plasticizer include biphenyl, biphenyl chloride O-terphenyl, p-terfeninopedibutyl phthalate, dimethyl glycol phthalate, dioctyl phthalate, triphenyl phosphoric acid, and the like.

The electrophotographic printing plate used in the present invention can be produced by a known process using the above-mentioned electrophotographic photoreceptor. That is, it is charged substantially uniformly in a dark place, and an electrostatic latent image is formed by imagewise exposure. As for the exposure method,
Examples include scanning exposure using a semiconductor laser, HeNe laser, etc., reflection image exposure using a xenon lamp, tungsten lamp, fluorescent lamp, etc. as a light source, and contact exposure using a transparent positive film. Next, the electrostatic latent image is developed with toner. As the developing method, various conventionally known methods such as cascade development, magnetic brush development, powder cloud development, and liquid development can be used. Among these, liquid development is capable of forming fine images and is suitable for creating printing plates. The formed toner image can be fixed by a known fixing method, such as heat fixing, pressure fixing, solvent fixing, or the like. A printing plate can be prepared by allowing the toner image thus formed to act as a resist and removing the photoconductive layer in non-image areas with an etching solution.

As the etching solution for removing the photoconductive insulating layer in the non-image area after toner image formation, any solvent can be used as long as it can remove the photoconductive insulating layer, and is not particularly limited. Preferably, alkaline solvents are used. The alkaline solvent referred to here is an aqueous solution containing an alkaline compound, an organic solvent containing an alkaline compound, or a mixture of an aqueous solution containing an alkaline compound and an organic solvent. Examples of alkaline compounds include IJium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, potassium silicate, sodium metasilicate, potassium metasilicate, sodium phosphate, potassium phosphate, ammonia, and monoethanolamine, Any organic or inorganic alkaline compounds such as amino alcohols such as jetanolamine and triethanolamine can be mentioned. As mentioned above, water or many organic solvents can be used as the solvent for the etching solution, but from the viewpoint of odor and pollution, an etching solution mainly composed of water is preferably used.

If necessary, various organic solvents can be added to the etching solution mainly composed of water. Preferred organic solvents include lower alcohols and aromatic alcohols such as methanol, ethanol, propanobebutanol, benzyl alcohol, and phenethyl alcohol, as well as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, cellosolves, monoethanolamine, and Amino alcohols such as tanolamine and triethanolamine can be mentioned. Further, the etching solution used contains a surfactant, an antifoaming agent, and various other additives as necessary.

It is preferable that the toner forming the image area contains a resin component having resist properties to the etching solution. Examples of resin components include acrylic resins using methacrylic acid, methacrylic esters, etc., vinyl acetate resins, copolymers of vinyl acetate and ethylene or vinyl chloride, vinyl chloride resins, pyridene chloride resins, and vinyls such as polyvinyl butyral. Acecool resin, polystyrene, copolymers of styrene and butadiene, methacrylic esters, etc., polyethylene, polypropylene and its chlorinated products, polyester resins (e.g., polyethylene terephthalate, polyethylene isophthalate, polycarbonate to bisphenol), polyamide resins ( Celluloses such as polycapramide, polyhexamethylene acipamide, polyhexamethylene sebamate), phenolic resins, xylene resins, alkyd resins, vinyl-modified alkyd resins, gelatin, carboxyl methylcellulose, etc.
7. Examples include chill derivatives, waxes, polyolefins, and waxes.

In the electrophotographic photoreceptor used in the present invention, if necessary, casein, polyvinyl alcohol, ethyl cellulose, phenol resin, styrene-maleic anhydride copolymer, polyacrylic acid, Monoaminomonocarboxylic acids such as monoethanolamine, jetanolamine, trimethanolamine, tripropaturamine, triethanolamine and their hydrochlorides, oxalates, phosphates, amine acetic acid, alanine; examples: ebaserine, threonine, dihydroxy Oxyamino acids such as ethylglycine; Sulfur-containing amino acids such as cysteine and cystine; Monoaminodicarboxylic acids such as aspartic acid and glutamic acid; Diaminomonocarboxylic acids such as lysine; such as p-hydroxyphenylglycine, phenylalanine, anthrani Acid aroma 8
Prokaryotic amino acids; e.g., tryptophan, proline, and other heterocyclic amino acids; e.g., sulfamic acid,
Aliphatic aminosulfonic acids such as cyclohexylsulfamic acid; for example, ethylenediaminetetraacetic acid, nitrilotriacetic acid, iminodiacetic acid, hydroxyethyliminodiacetic acid, hydroxyethylethylenediaminetriacetic acid, ethylenediaminediacetic acid, cyclohexanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, glycol ether (poly)aminopolyacetic acids such as diaminetetraacetic acid; and some or all of the acid groups of these compounds) IJium salts, potassium salts,
An intermediate layer made of ammonium salt or the like may be provided for the purpose of improving the adhesion between the substrate and the photoconductive layer, the electrostatic properties, elution properties and/or printing properties of the photoconductive layer.

Further, an overcoat layer that can be dissolved when the photoconductive layer is removed can be provided on the photoconductive layer, if necessary, for the purpose of improving the electrostatic properties of the photoconductive layer, the development properties during toner development, or the image properties. This overcoat layer may be mechanically matted or a resin layer containing a matting agent. Matting agents include silicon dioxide, zinc oxide, titanium oxide, zirconium oxide, glass particles, alumina, starch, polymer particles (e.g. particles of polymethyl methacrylate, polystyrene, phenolic resin, etc.) and U.S. Pat. No. 2,710,245. and the matting agents described in US Pat. No. 2,992,101. Two or more of these can be used in combination. The resin used in the resin layer containing the matting agent is appropriately selected depending on the combination with the etching solution used. Specifically, for example, gum arabic, glue, gelatin, casein, celluloses (tatoehabiscose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, etc.), starches (such as soluble starch, (modified starch, etc.), polyvinyl alcohol, polyethylene oxide, polyacrylic acid, polyacrylamide,
Polyvinyl methyl ether epoxy resin, phenolic resin (especially preferred is novolak type phenolic resin),
Examples include polyamide and polyvinyl butyral. Two or more of these can be used in combination.

(Examples) The present invention will be explained in more detail by Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. In addition, in the examples, all parts or % indicate parts by weight or % by weight unless otherwise specified.

Examples 1 to 7 and Comparative Examples 1 and 2 The surfaces of JIS 1050 aluminum sheets were grained with a rotating nylon brush using a pumice water suspension as an abrasive. The surface roughness at this time (center line average roughness) is 0.5
It was μ. After washing with water, it was immersed in a 10% caustic soda aqueous solution at 70°C and etched so that the amount of aluminum dissolved was 6 g 7 m 2 . After washing with water, it was neutralized by immersing it in a 30% nitric acid aqueous solution for 1 minute, and was thoroughly washed with water. After that, in a 0.7% nitric acid aqueous solution, an anode special voltage of 13 volts,
Electrolytic surface treatment was performed for 20 seconds using a rectangular alternating waveform with a cathode special voltage of 6 volts (described in Japanese Patent Publication No. 1987-191), and the surface was cleaned by immersing it in a 50°C solution of 20% sulfuric acid. After that, I washed it with water. Furthermore, anodization treatment was performed in a 20% sulfuric acid aqueous solution so that the weight of the anodized film was 3.0 g/m2, and after washing and drying, 28 m of β-alanine was added.
A substrate was prepared by coating and drying to give a coating weight of g/m2.

The following photoconductive layer coating solution was applied onto this substrate using a bar coater and dried at 120° C. for 10 minutes to prepare a photoreceptor for electrophotographic engraving.

(Coating liquid for photoconductive layer) Hydrazone compound shown below 25 parts Copolymer of benzyl methacrylate and meccrylic acid (30 mol% meccrylic acid) Thiopyrylium salt compound shown below 75 parts 1.18 parts Methylene chloride 510 parts Methyl cellosolve acetate 150 copies The dry film thickness of the photoreceptor for electrophotographic engraving thus prepared was 4 μm.

Next, this sample was charged with a surface potential of ++ using a corona charger in a dark place.
After being charged to 400 V, it was exposed to tungsten light and developed with a liquid developer Ricoh MRP (IJ Coco Co., Ltd.), thereby making it possible to obtain a clear positive image. Further, the created image was heated at 120° C. for 2 minutes to fix the toner image.

This non-image area was removed with an etching solution prepared by diluting 40 parts of potassium silicate, 10 parts of potassium hydroxide, and 100 parts of ethanol in 800 parts of water, and the film was thoroughly washed with water.

On the other hand, an aqueous solution A having the following composition was prepared, and while vigorously stirring, solution B having the following composition was gradually added thereto to form an emulsion, which was further emulsified with a homogenizer to obtain a plate protection agent.

Aqueous solution A Gum Arabic 4g Dextrin 16g Phosphoric acid (85%
) 0.2g water
75 g Solution B Sodium dilauryl sulfosuccinate 1.0 g Dibutyl phthalate 2.0 g Alkylphenyl type nonionic surfactant (Table 1) 1.0 g Rosin ester (manufactured by Arayo Kagaku ■) 0.5 g The photoreceptor was subjected to a series of electrophotographic processes and etching processes as described above using the plate protective agent shown in Table 1, and was processed according to the method for using the plate protective agent as described above to obtain a plate-making printing plate. And so.

These printing plates were simultaneously and repeatedly printed several times using an Oliver 52 (Kikuhansai Molton printing press).

The ink is DICCAPS-G ink (large book ink), and the dampening water is Btl-3 (-Fuji Photo Film) at a ratio of 1:100 (
water) and used.

The oil sensitivity of a printing plate is determined by the number of sheets from the start of printing until a printed matter with sufficient ink density is obtained (hereinafter referred to as the number of printed sheets).

).

The results are shown in Table 1.

Example 8 The following photoconductive layer dispersion was applied to the substrate in Example 1 using a bar coater to prepare a photoreceptor for electrophotographic engraving.

Dispersion liquid for photoconductive layer Trisazo compound 1.0 parts Copolymer of vinyl acetate and crotonic acid (RESYN No. 28-1310 manufactured by Kanebo NSC Co., Ltd.) 10 parts Tetrahydrofuran 100 parts in a 500-glass container Add the glass peas to the paint shaker (
The mixture was dispersed for 60 minutes at Toyo Seiki Seisakusho Co., Ltd. to prepare a photoconductive layer dispersion.

The thickness of this photoconductive layer was about 4 microns. Example 1
Toner development and etching were performed in the same manner as above.

After washing the obtained lithographic printing plate with water and squeezing it, gum bowing was performed using each plate surface protective agent shown in Table 2 below.
It was dried at 0°C for 5 minutes. After leaving each plate at 20°C for 7 days, wash with water to remove the plate surface protectant, and print using the normal procedure. (hereinafter referred to as the number of printed sheets) and stains on the non-image areas of printed matter (hereinafter simply referred to as stains).

I looked into it. The results are shown in Table 2.

From the results shown in Table 2 and above, it can be seen that the plate surface protectant of the present invention has an excellent effect of not reducing the oil sensitivity of the image area of the printing plate and causing no staining.

Example 9 The same procedure as in Example 3 was carried out, except that monosolvent was used instead of sibutyl slate as the organic solvent of the plate surface protectant. The printing results were similar to those obtained in Example 3.

Examples 10 to 16 and Comparative Examples 3 and 4 Printing plates were made in the same manner as in Example 1, but using the following as a plate surface protectant, and their oil sensitivity was examined. The results are shown in Table 3. For the plate surface protectant, prepare the following aqueous solution C and solution solution.
It was obtained by emulsification in the same manner as in Example 1.

Aqueous solution C Gum arabic dextrin phosphoric acid (85%) Aqueous solution D Sodium di(2-ethylhexyl)sulfosuccinate 1.0 g Dioctyl phthalate 2.0 g Alkylphenyl type nonionic surfactant (Table 3) 10 g Rosin ester (for rough use) Made by Kagaku ■) 0.5gg 6 g 0.2g 5 g 5? From the results in Table 3, it can be seen that when the plate surface protectant according to the present invention is used, the resulting lithographic printing plate does not have its oil sensitivity reduced and has excellent performance.

Claims (1)

[Claims] A lithographic printing plate in which the image area consists of a toner image formed by an electrophotographic process on a photoconductor layer provided on a conductive substrate and the non-image area is a conductive substrate is prepared by dissolving a hydrophilic polymer compound. Treatment with an emulsified plate surface protectant consisting of an aqueous phase and an oil phase containing an organic solvent, an alkylphenyl type nonionic surfactant with an HLB of 14 or less, and an anionic surfactant. Characteristic desensitizing method for lithographic printing plates.