JPH0218571A - Plate making method for planographic printing plate - Google Patents

Abstract

PURPOSE:To obviate the generation of anomalous insoluble matter and gels in rinse baths after a rinse processing by executing the rinse processing with the plural rinse baths and processing the printing plate at the pH of the rinse baths lower toward the later stages. CONSTITUTION:A photosensitive body for plate making contg. a hydrazone compd., etc., is uniformly electrified and is subjected to image exposing to form an electrostatic latent image on said body. After the image is developed with a toner, the non-image part is removed by an etching liquid and is subjected to the rinse processing to produce the printing plate. The rinse processing is executed with the plural baths and at the pH of the baths lower toward the later stages. The rinse processing by setting the pH of the first bath at 10-13 and the pH of the final bath at 3-9. A buffer soln. such as sodium phosphate, anionic surfactant such as alkyl diphenylether disulfonate, etc., may be incorporated into the rinse baths.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a plate-making method for creating a lithographic printing plate by an electrophotographic process, and particularly relates to a plate-making method with an improved rinsing step after etching treatment. be.

[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 printers 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 plotter (e.g. He-N
This is because it is difficult to develop a direct printing plate with a sensitivity high enough to make a printing plate within a practical time using e-lasers, semiconductor lasers, etc.).

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. 47-47610 and Japanese Patent Publication No. 48
-40002, Special Publication No. 18325, Special Publication No. 18325, Special Publication No. 18325
Zinc oxide-resin dispersion offset printing plate materials described in Japanese Patent Publication No. 1-15766 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. The tea is used after wetting with a fat-sensitizing solution (for example, a ferrocyanate or an acidic aqueous solution containing a ferricyanide). Off-cent 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 will deteriorate. However, there are also drawbacks such as deterioration of the image. It also has the disadvantage of using harmful cyanide compounds as desensitizing solutions.

Special Publication No. 37-17162, Special Publication No. 38-7758,
Organic photoconductor resin printing plate materials described in Japanese Patent Publication No. 46-39405, Japanese Patent Publication No. 52-2437, etc.
For example, an electrophotographic photoreceptor is used in which a photoconductive insulating layer made of an oxazole or oxadiazole compound bound with a styrene-maleic anhydride copolymer is provided on a grained aluminum plate. After forming a toner image on the toner image by electrophotography, a printing plate is formed by dissolving and removing the non-image area with an alkaline organic solvent.

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-59-15245
No. 6, JP 59168462, JP 58-145
Dye-sensitized electrophotographic photoreceptors described in No. 495 and the like are known.

When plate-making a lithographic printing plate using these electrophotographic photoreceptors, a toner image is formed by an electrophotographic process, the non-image area is dissolved and removed, and then washed with running water or recirculated washing water, and then washed several times. Washing is performed in a multi-stage water wash consisting of several baths.

This water washing step removes developer components and components eluted from the photosensitive layer from the developed printing plate to clean it and prevent troubles during subsequent printing.

However, when the developer brought into the washing bath is diluted by the washing water, components of the photosensitive layer that have been dissolved and dispersed in the developer often precipitate, producing abnormal insoluble matter.

For example, a (meth)acrylic acid copolymer resin often used as the main binder component of a photosensitive layer is dissolved in an alkaline developer, but when it is brought into a water washing bath and the pH is lowered, it precipitates.

Particularly in the method of circulating washing water in automatic processing machines, etc., these insoluble substances generated in the washing water may clog the spray nozzle or adhere to pipes or tanks, causing problems in the circulation of the washing water. is often the case.

Furthermore, this insoluble matter may adhere to the printing plate, causing stains in non-image areas.

By the way, in order to prevent the generation of insoluble matter in the washing water, it is conceivable to add a complexing agent to the washing water or to use water with a hardness of 100 or less as the washing water.

However, although these techniques are effective for troubles caused by insoluble matter caused by polyvalent metal ions in the washing water, they do not allow the photosensitive layer components dissolved and dispersed in the developer to generate abnormal insolubilized matter in the washing water. It was not effective at all for the trouble caused by.

On the other hand, silicates are generally used as an etching solution component for eluting the non-image areas of lithographic printing plates, but the silicates carried from the etching bath to the washing bath by the etched printing plate are dissolved in the washing water. It often formed silica gel, which interfered with the circulation of flush water.

Further, when the washing water is recycled, the pH of the washing water increases rapidly due to the introduction of the alkaline etching solution. At this time, when the pH of the final washing bath was 9.5 or more, there were effects such as poor ink receptivity and printing stains at the start of printing.

Therefore, the life of conventional circulating water washing water is short, and it is necessary to frequently replace the water with new water.

Alternatively, there is a method of rinsing after etching by circulating a so-called rinsing solution containing surfactants and pH buffering agents, but even with this method, it is not possible to suppress the increase in pH, and the amount of processing is limited. There was a limit.

[Problems to be solved by the present invention]

Therefore, an object of the present invention is to provide a rinsing bath (hereinafter referred to as
The purpose of the present invention is to provide a plate-making method that does not produce abnormal insoluble matter or gel in a rinsing bath (including a water washing bath) and can stably produce a large amount of printing plates over a long period of time.

[Means to solve the problem]

Therefore, the present inventors have made extensive studies to solve the above-mentioned problems, and as a result, have come up with the present invention.

That is, the present invention provides 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, in which the lithographic printing plate is subjected to a rinsing treatment after removing the non-image area. In a method for making a printing plate, rinsing is performed in a plurality of rinsing baths, and the pH of the rinsing baths is
This is a method for making a lithographic printing plate, characterized in that the lithographic printing plate is made lower toward the later stages.

According to a preferred embodiment of the invention, the pH of the initial rinsing bath is 10-13 and the pH of the final rinsing bath is 3-9, preferably 6-9.

The present invention will be explained in detail below.

The most important thing in the present invention is the pH of multiple rinse baths.
In order to do this, various water-soluble compounds are added to the rinsing solution, which may increase the throughput of the printing plate, the amount of evaporation, the amount taken out by the printing plate, or the pH of the rinsing solution. will be replenished accordingly.

In this case, it is particularly preferable to contain a buffer.

Details of such water-soluble compounds and buffering agents are described, for example, in "Chemistry Handbook Basic Edition ■", Chemical Society of Japan, February 20, 1971, 5th edition, published by Maruzen Co., Ltd., pages 1312-1320. These can be used as they are in the present invention. Suitable acids and water-soluble salts include inorganic acids such as molybdic acid, boric acid, nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, acetic acid, oxalic acid, tartaric acid, benzoic acid, succinic acid, citric acid, malic acid, lactic acid, p- ) Examples include acids such as water-soluble organic acids such as luenesulfonic acid and their salts. More preferred salts are water-soluble alkali metal salts and ammonium salts, and particularly preferred are molybdates such as ammonium molybdate, phosphates such as sodium phosphate, polyphosphates such as potassium tetrapolyphosphate and trimetaphosphate, These are oxalates such as sodium oxalate, tartrates such as potassium tartrate, succinates such as sodium succinate, and citrates such as ammonium citrate. These compounds can be used alone or in combination of two or more. The amount added is not particularly limited, but the total amount of acid and salt is preferably about 10% by weight or less, more preferably 0.01% by weight or less, based on the total weight of the rinse liquid.
It is used in a range of 6% by weight.

The rinsing liquid used in the present invention preferably contains a surfactant for the purpose of improving cleaning properties and protecting the image area of the printing plate.

Examples of such surfactants include nonionic surfactants such as polyoxyethylene alkylethenope polyoxyethylene alkyl phenylethenope polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbicun fatty acid ester, and ethenope glycerin fatty acid ester. Surfactants, such as fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyldiphenyl ether disulfonates, dialkyl sulfosuccinate ester salts, alkyl phosphate ester salts, naphthalene sulfonic acid formalin condensates, polyesters, Included are anionic surfactants such as oxyethylene alkyl sulfate salts, and cationic surfactants such as alkyl amine salts, quaternary ammonium salts, polyoxyethylene alkyl amine salts. Among these, anionic surfactants such as alkyl diphenyl ether disulfonate and naphthalene sulfonic acid formalin condensate are preferred. The above surfactants can be used alone or in combination of two or more, and about 0.0% (more preferably 0.0% by weight than 11 to 10% by weight) in the rinsing liquid.
It is used in a range of 1 to 2% by weight.

It is preferable that the surfactant be contained in all of the rinsing liquids of a plurality of rinsing baths, but it may be contained in only the rinsing liquids of some of the baths.

The rinse liquid used in the present invention may further contain a lipophilic substance. As a result, the image area of the lithographic printing plate exhibits higher oil sensitivity. Preferred lipophilic substances include, for example, organic carboxylic acids having 5 to 25 carbon atoms such as oleic acid, lauric acid, valeric acid, nonylic acid, capric acid, mystilic acid, palmitic acid, castor oil, and the like. These lipophilic substances can be used alone or in combination of two or more, and are solubilized or emulsified with the above-mentioned surfactant.

These lipophilic substances are about 0.005% to 10% by weight, more preferably 0.05 to 5% by weight of the rinse solution.
It can be contained within the range of .

Further, it is preferable that the rinsing liquid used in the present invention contains an antifoaming agent such as an organic silane compound.

The electrophotographic printing plate used in the present invention can be produced by a known process using the electrophotographic photoreceptor described below. 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, He--Ne 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 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. For etching liquids based on water, if necessary,
Various organic solvents can also be added. Preferred organic solvents include A methanol, propanobebutanol,
Examples include lower alcohols and aromatic alcohols such as penzyl alcoholobephenethyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, cellosolves, and amine alcohols such as monoethanolamine, jetanolamine, and triethanolamine. I can do it.

The etching solution used in the present invention may further contain a surfactant. This allows the etching solution to wet the surface of the photosensitive layer of the electrophotographic photoreceptor well, improving the processing ability of the etching solution (the amount of photosensitive layer that can be dissolved and removed by a unit volume of the etching solution).
Furthermore, it is possible to widen the range of etching processing conditions (temperature, processing time, etc.) that provide optimal results. Preferred such surfactants include anionic surfactants and amphoteric surfactants. Preferred examples of anionic surfactants include alkylbenzene sulfonates (such as sodium dodecylbenzene sulfonate)
The number of carbon atoms in the alkyl group is 8 to 18, more preferably 12 to 16), for example, alkylnaphthalene sulfonates such as sodium isopropylnaphthalene sulfonate (the number of carbon atoms in the alkyl group is 3 to 10), naphthalene sulfone These include formalin condensates of acid salts, dialkyl sulfosuccinates (the alkyl group has 2 to 18 carbon atoms), dialkylamide sulfonates (the alkyl group has 11 to 17 carbon atoms), and the like. Preferred specific examples of amphoteric surfactants include imitasoline derivatives, such as N-alkyl-NN N-tris(carboxymethyl)ammonium (the alkyl group has 12 to 18 carbon atoms), N-alkyl-N-carboxymethyl-NN -Vequin-type compounds such as dihydroquinethylammonium (the number of alkyl groups is 12 to 18) are included. The amount of surfactant to be used is not particularly limited, but for boat fishing, it is contained in the etching solution at a concentration of about 0.003 to about 3% by weight, more preferably 0.006 to 1% by weight.

The etching solution used in the present invention may further contain an antifoaming agent. Suitable antifoam agents include U.S. Pat. No. 3,250,727;
British Patent No. 1. 382. No. 901, No. 1,387
There are compounds described in various specifications such as No. 713. Among these, organic silane compounds are preferred.

Various methods are possible for etching an electrophotographic photoreceptor on which a toner image has been formed using the etching solution as described above. Specifically, methods include immersing a photoreceptor on which a toner image has been formed in an etching solution, spraying the etching solution onto the photosensitive layer of the photoreceptor from a number of nozzles, and using a sponge moistened with the etching solution. Examples include a method of wiping the photosensitive layer of the photoreceptor, a method of applying an etching solution to the surface of the photoreceptor layer of the photoreceptor with a roller, and the like. Further, after the etching solution has been applied to the photosensitive layer of the photoreceptor in this manner, the surface of the photosensitive layer can be lightly rubbed with a plan or the like. Etching processing conditions can be appropriately determined by those skilled in the art depending on the above-described etching method. - For example, in an etching method using immersion, about YO to 80
She is raped for a second.

The lithographic printing plate obtained as described above is preferably squeezed to reduce the amount of etching solution on the plate surface. In the present invention, the amount of etching solution remaining on the plate surface of the lithographic printing plate after being squeezed is preferably 20 mβ/m' or less on both the front and back surfaces, and it is preferable that this amount is as small as possible. Therefore, the residual amount of the etching solution is more preferably 10 mβ/m' or less, most preferably 5 mβ/m' or less. If the length after squeezing is more than 20 mβ/m', the rinsing liquid used in the present invention deteriorates more quickly, so it is necessary to increase the amount of replenishment, which increases running costs including waste liquid treatment, which is not preferable.

A method for squeezing the plate surface of a planographic printing plate includes, for example, a method in which the plate is passed between a pair of elastic rollers whose surfaces are coated with an elastic member such as rubber, and the etching liquid on the plate surface is removed by the nip pressure. Alternatively, a method may be adopted in which an elastic plastic material with a smooth surface is placed along the transport path of the lithographic printing plate and brought into sliding contact with the plate surface to scrape off the developer from the plate surface.

The lithographic printing plate thus obtained is rinsed according to the method of the present invention. Specific processing methods include immersion in a bath filled with a rinsing solution, spraying the rinsing solution onto the print, and applying the rinsing solution with a roller.

In conventional rinsing with running water or circulating water, components of the photosensitive layer that were dissolved or dispersed in the etching solution precipitate in the rinsing area, producing insoluble matter. For example, when an electrophotographic planographic printing plate using a (meth)acrylic acid copolymer resin is treated with an alkaline etching solution containing a silicate, the (meth)acrylic acid copolymer resin, which is the main component of the photosensitive layer, is alkaline. However, when the etching solution is diluted with water and the pH becomes low, it precipitates, causing clogging of the spray, staining of the rinse bath, and staining of prints.

Furthermore, when the etching solution was neutralized or diluted with a rinsing solution that contained a buffering agent that had a strong buffering effect near neutrality, the silicate gelled and became agar-like, which caused problems in the circulation of the rinsing solution. .

The present invention is characterized in that the rinsing process is performed using a plurality of rinsing baths, and the pH of the rinsing baths is made lower as the process progresses. Therefore, according to the present invention, since the pH of the initial rinsing bath is set relatively high, the pH does not drop suddenly even if the etching solution brought in is diluted. Therefore, there is no precipitation of insoluble matter or the formation of silica gel, and a large quantity of printing plates can be stably produced over a long period of time.

The lithographic printing plate obtained by processing in this manner can be subjected to various processes such as development ink application, correction such as addition or erasure, and gumming, and any of these processes can be carried out. This can be done efficiently without any problems.

The present invention will be explained in more detail.

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 b, particularly 0.1 to 0.5 m+n. 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 grease from the surface of the aluminum plate, degreasing treatment is performed using a surfactant or an alkaline aqueous solution, 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, puff 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 processing 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, the liquid temperature is 5 to 70°C, and the current density is 5. ~60A/
dm', a voltage of 1 to 100 V, and an electrolysis time of 10 seconds to 50 minutes. The amount of anodic oxide film is 0.1~
10 g/m' is suitable, more preferably 1 to 6
g/m' range.

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-ternope cadmium sulfide, and zinc oxide. Further, as organic photoconductive compounds, 1) triazole derivatives described in U.S. Patent No. 3.112.197 etc., 2) U.S. Pat.
3) Imidazole derivatives described in Japanese Patent Publication No. 37-16,096, etc., 4) U.S. Patent No. 3,615,402, 3820.9
No. 89, No. 3,542,544, Special Publication No. 45-555
No. 51-10,983, JP-A-51-93, 22
No. 4, No. 55-108 667, No. 55-15695
Polyarylalkane derivatives described in U.S. Pat. No. 3, No. 56-36゜656, publications, etc.;
No. 46, JP-A No. 55-88,064, JP-A No. 55-88,
No. 065, No. 4L-105, 537, No. 55-51.
No. 086, 56-. No. 80051, 56-88, 1
No. 41, No. 57-45.545, No. 54-112, 6
Pyrazolone derivatives and pyrazolone derivatives described in No. 37, No. 55-74,546, publications, etc.
6) U.S. Patent No. 3,615,404, Special Publication No. 51-1
No. 0,105, No. 46-3.712, No. 47-28,
No. 336, JP-A-54-83,435, JP-A No. 54-11
7) U.S. Pat. No. 3,567.450, U.S. Pat. No. 3,180.
No. 703, No. 3,240,597, No. 3゜658.5
No. 20, No. 4,232,103, No. 4.175,96
No. 1, No. 4,012,376 West German Patent (DAS) 1
, 110.518, JP 49-35,702, JP 39-27.577, JP 55-144.250, JP 56119.132, JP 56-22,437 specifications, publications 8) Amino-substituted chalcone derivatives described in U.S. Patent No. 3,526,501, 9) N, N described in U.S. Patent No. 3,542,546, etc. - Bicalbasil derivatives, 10) Oxazole derivatives described in U.S. Patent No. 3,257.203, etc., 11) Styryl anthracene derivatives described in JP-A-56-46,234, etc., 12) JP-A-54 Fluorenone derivatives described in -110,837, etc., 13) U.S. Patent No. 3,717.462, JP-A-1983-
No. 59,143 (corresponding to U.S. Patent No. 4,150°987), No. 55-52,063, No. 55-52,064
No. 55-46,760, No. 55-85,495, No. 57-11,350, No. 57-148,749, No. 57-104144, specifications, publications, etc. Derivatives, 14) U.S. Patent No. 4,047,948, 4°047
．． No. 949, No. 4,265,990, No. 4.273,
No. 846, No. 4,299.897, No. 4,306,0
Benzidine derivatives described in the specification of No. 08, etc., 15) JP-A-58-190,953, JP-A No. 5995.5
No. 40, No. 59-97,148, No. 59-195,6
Examples include stilbene derivatives described in Japanese Patent No. 58 and Japanese Patent No. 62-36,674.

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

16> Polyvinylcarbazole and its derivatives described in Japanese Patent Publication No. 34-10.966, 17) Japanese Patent Publication No. 43-1
Polyvinylpyrene, polyvinylanthracene, poly-2-vinyl-4(4'-dimethylaminophenyl)-5-phenyloxasonopeboly-3-vinyl-N described in No. 8,674 and No. 43-19.192 -Vinyl polymers such as ethylcarbazole, 18) Polymers such as polyacenaphthylene, polyindene, and copolymers of acenaphthylene and styrene described in Japanese Patent Publication No. 1988-19193, 19) Japanese Patent Publication No. 1986-19940 Condensation resins such as pyrene-formaldehyde resin, brompyrene-formaldehyde resin, and ethylcarbazole formaldehyde resin described in JP-A-56-90,883 and JP-A-56-161.
The various triphenylmethane polymers described in Publication No. 550, and the use of various pigments, dyes, etc., 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 are: 1) U.S. Patent No. 4,436.800;
No. 506, JP-A-47-37543, JP-A No. 58-123
, No. 541, No. 58-192,042, No. 58-21
No. 9,263, No. 59-78356, No. 60-179
, No. 746, No. 61148.453, No. 61-238
, No. 063, Special Publication No. 60-5941, No. 60-45,
Monoazo, bisazo, and trisazo pigments described in U.S. Patent No. 664, etc. 2) U.S. Pat.
Phthalocyanine pigments such as metal phthalocyanine or metal-free phthalocyanine described in US Pat. , thioindigo derivatives 5) Quinacridone pigments described in British Patent Box No. 2,237,679 etc. 6) British Patent Box No. 2,237,678, JP-A-59-1
Polycyclic bovine non-based pigments described in No. 84,348, No. 62-28,738, etc. 7) JP-A-47-. 8) Bisbenzimidazole pigments described in U.S. Pat. Nos. 30,331 and 8) U.S. Pat.
Squarium salt pigments described in JP-A No. 082, etc.; 9) Azlenium salt-based pigments, described in JP-A No. 5FLL-53,850, JP-A No. 61-212.542, etc.; "Page 125 (Kodansha 819'87), "Electron Photography" 129 (1973) r Organic Synthetic Chemistry J 2
4 No. 111010 (1966) and the like can be used. For example, 10) U.S. Pat. No. 3,141,770, U.S. Pat. No. 4,283.
No. 475, Special Publication No. 48-25,658, Japanese Patent Application Publication No. 62
Pyrylium-based dyes described in No.-71,965 etc. 11) Applied Optics Supplement
ement 3 50 (1969), Japanese Patent Application Publication No. 1973
-39. ．． 12) Cyanine dyes described in U.S. Pat.
Styryl dyes described in No. 588, No. 60-252.517, etc. These organic photoconductive materials may be used alone or in combination of two or more.

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. 58-10n 2.239, No. 58-129.439, No. 62-7
Examples include compounds described in No. 1,965 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 a photoreceptor for electrophotographic engraving, 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 the It is impossible to make general statements because it depends on the relative relationship between the image and the etching solution, such as its resistivity. As the binding resin, a polymer compound that is soluble or dispersible in the above-mentioned etching solution is preferred.

Specifically, for example, a copolymer of styrene and maleic anhydride, a copolymer of styrene and monoalkyl maleic anhydride, a methacrylic acid/methacrylic ester copolymer, a styrene/methacrylic acid/methacrylic ester copolymer Acrylic acid esters such as acrylic acid/methacrylic acid ester copolymer, styrene/acrylic acid/methacrylic acid ester copolymer, vinyl acetate/crotonic acid copolymer, vinyl acetate/crotonic acid/methacrylic 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, quinolene 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 electrophotolithography, and have good results. can be used.

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. Particularly preferred among the phenolic resins are phenol, O-cresol, m-
Examples include novolac resins obtained by condensing cresol or p-cresol 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 sensitivity decreases if the content of the photoconductive compound is small, so the amount of the photoconductive compound should be 0.05 part by weight or more per 1 part by weight of the binding resin. Preferably, it can be used in an amount of 0.1 part by weight or more. Furthermore, if the thickness of 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 "Zide etch" will occur during etching, making it impossible to obtain a good image. -30μ, more preferably 05-10μ can be used.

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, use a dispersion machine such as a ball mill, paint shaker, or Guinino Beat Lighter. It is used after being dispersed to a particle size of 5 μm to 0.1 μm. The binding resin and other additives used in the photoconductive layer can be added during or after dispersing the pigment. The coating liquid prepared in this way can be applied by spin coating, blade coating, knife coating, reverse roll coating,
A printing plate for electrophotolithography can be obtained by coating and drying on a substrate by a known method such as dip coating, rod bar coating, or spray coating. As a solvent for creating a coating solution,
Halogenated hydrocarbons such as dichloromethane, dichloroethane and chloroform, alcohols such as methanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, glycol ethers such as ethylene glycol monomethyl ether and 2-methoxyethyl acetate, tetrahydrofuran, Examples include ethers such as 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, 0-terphenyl p-terphenyl, dibutyl phthalate, dimethyl glycol phthalate, dioctyl phthalate, triphenyl phosphoric acid, and the like.

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 acid esters, etc., vinyl acetate resins, copolymers of vinyl acetate and ethylene or vinyl chloride, vinyl chloride resins, vinylidene 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 of bisphenol A), polyamide resins ( e.g., polycapramide, polyhexamethylene adiboamide, polyhexamethylene sebamide), phenolic resins, xylene resins, alkyd resins, vinyl-modified alkyd resins, gelatin, cellulose ester derivatives such as carboxymethyl cellulose, waxes, polyolefins, and waxes. and so on.

In the electrophotographic photoreceptor used in the present invention, casein, polyvinylalconopethyl cellulose, phenol resin, styrene-maleic anhydride copolymer, polyacrylic acid, etc. are optionally added between the conductive substrate and the photoconductive layer. , monoethanolamine, jetanolamine, trimethanolamine, tripropaturamine, triethanolamine and their hydrochlorides, oxalates, phosphates, aminoacetic acid, monoamino monocarboxylic acids such as alanine; for example, serine, threonine, Oxyamino acids such as dihydroxyethylglycine; Sulfur-containing amino acids such as cysteine and cystine; Monoamino dicarboxylic acids such as aspartic acid and glutamic acid; Diaminomonocarboxylic acids such as lysine; such as p-hydroxyphenylglycine, phenylalanine, anthranils Amino acids with an aromatic nucleus such as acids; Amino acids with a heterocycle such as tryptophan and zololine; Aliphatic aminosulfonic acids such as sulfamic acid and cyclohexylsulfamic acid; For example, ethylenediaminetetraacetic acid, nitrilotriacetic acid,
(Poly)aminopolyacetic acids such as iminodiacetic acid, hydroxyethyliminodiacetic acid, hydroxyethylethylenediaminetriacetic acid, ethylenediaminediacetic acid, cyclohexanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, glycol etherdiaminetetraacetic acid; and one of the acid groups of these compounds (Partial or total removal) An intermediate layer made of IJum salt, potassium salt, ammonium salt, etc. is used to improve the adhesion between the substrate and the photoconductive layer, the electrostatic properties, elution properties, and/or printing properties of the photoconductive layer. It can be provided for any purpose.

Furthermore, 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 quality. . This overcoat layer is
It may be a mechanically matted layer or a resin layer containing a matting agent. As matting agents, silicon dioxide, zinc oxide, titanium oxide, zirconium oxide, glass particles, alumina, starch, polymer particles (for example, particles of polymethyl methacrylate, polystyrene, phenolic resin, etc.) and US Pat. 710. 245 and U.S. 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 (e.g., viscose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroquinepropylmethylcellulose, carboxylmethylcellulose, etc.), starches (e.g., soluble starch, modified starch, etc.), polyvinyl alcohol Examples include polyethylene oxide, polyacrylic acid, polyacrylamide, polyvinyl methyl ether, epoxy resin, phenol resin (novolak type phenol resin is particularly preferred), polyamide, polyvinyl butyral, and the like. 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.

Example I The surface of a JIS1050 aluminum sheet was grained using a rotating nylon brush using a pumice water suspension as an abrasive. The surface roughness (center line average roughness) at this time is 0. 5μ
Met. After washing with water, it was immersed in a 10% caustic soda aqueous solution at 70°C and etched so that the aluminum dissolution rate was 6 g/m'.

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. Then 0. In a 7% nitric acid aqueous solution, electrolytic surface treatment was performed for 20 seconds using a square wave alternating waveform with an anode special voltage of 13 volts and a cathode special voltage of 6 volts (described in Japanese Patent Publication No. 1987-19191), and 20% sulfuric acid. 50℃
After washing the surface by immersing it in a solution, it was washed with water. Furthermore,
The weight of the anodized film in 20% sulfuric acid aqueous solution is 3. Og/m
A substrate was prepared by performing anodizing treatment so that the result was ', washing with water, and drying.

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 25 parts of the hydrazone compound shown below 75 parts of a copolymer of benzyl methacrylate and methacrylic acid (30 mol% methacrylic acid) 1.18 parts of the following thiopi-IJ salt compound \ 510 parts of methyl Cerunulf acetate 150 parts The dry film thickness of the electrophotographic photoreceptor 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 Co.), 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.

Next, an etching process was performed using an automatic processing machine as shown below, an etching solution, and washing water.

(1) Automatic processing machine Consists of an etching bath and two subsequent rinsing baths; a drive device that horizontally transports the electrophotographically developed lithographic printing plate; and a storage tank for transporting the processing liquid from each processing bath → pump → spray →
This is an automatic processing machine that has a nozzle storage tank, a circulation device, and a replenishment device for each processing bath, and the storage tank of each processing bath has a mechanism to discharge excess processing liquid by overflow.

(2) Etching liquid The following etching solution was put into an etching bath.

Potassium silicate 40 parts Potassium hydroxide 10 parts Ethanol
100 parts pure water 80
0 parts (3) First rinsing solution A rinsing solution (pH 10,7) 81 consisting of the following composition was put into the first rinsing bath, and 40 ml of the rinsing solution was replenished every time one 1003 mm x 800 mm printing plate was processed. The bath storage tank is designed to overflow at 81).

(Composition) Phosphoric acid-sodium hydroxide (buffer solution of pH 10.7) ・・・・・・・・・100
0g Sodium dodecyl diphenyl ether disulfonate 10
g (4) Second rinsing solution A rinsing solution (pH 6,5) 8β having the following composition was added to the second rinsing solution, and 40 rrl of the second rinsing solution was replenished every time a 1003 mm x 800 + n + n printing plate was processed. The rinse bath also has a structure that overflows at 8f!).

(Composition) Sodium dodecyl phenyl ether disulfonate (40% by weight aqueous solution) 10 g Phosphoric acid-sodium hydroxide aqueous solution (buffer solution with pH 6.5) 1000 g
Even when 60 lithographic printing plates of size 1003mm x 800+++n+ were processed continuously under the above conditions, no abnormal scum or gel was produced in the 1st and 2nd rinsing baths, and all printing plates from the 1st plate to the 60th plate opening were processed. Over the years, no malfunctions such as stains in non-image areas were observed.

In addition, after processing 80 sheets, the p of the first and second rinsing liquids
H was 12.2.7.3, respectively.

Comparative Example 1 Both the first rinsing bath and the second rinsing bath were treated under the same conditions as in Example 1, except that 8β of tap water was added to each and no replenishment was made depending on the treatment. After 10 sheets were processed, Abnormal insoluble matter began to float in the first rinsing solution, and 15
It adhered to the non-image area on the printing plate, and when it was printed on an offset printing machine, stains appeared in that area.

When the process was continued, the ink adhesion to the image area at the start of printing gradually deteriorated from around the 70th sheet, and a thin layer of ink also adhered to the non-image area, causing the printed matter to become thin. It caused stains.

Note that the pH of the second rinsing liquid at this time was 9.9.

Example 2 Electrophotographic photoreceptor and etching solution of Example 1,
An automatic processing machine containing the first rinsing liquid and the second rinsing liquid was prepared.

Furthermore, an etching replenisher having the following composition was prepared.

(Etching replenisher composition) Potassium silicate 40 parts Potassium hydroxide 20 parts Ethanol
100 parts pure water 8
00 copies 1003 mm x electrophotographically developed in the same manner as in Example 1
Each time one 810O3 plate was processed, 50 mβ of etching replenisher was added. Further, the second rinsing bath was also replenished with the second rinsing liquid at a rate of 40 mR/m' every time one plate was processed, and the first rinsing bath was directly replenished with the overflow liquid of the second rinsing bath.

When 60 printing plates were processed every day under the above conditions,
After 5 days, the pH of the first and second rinse solutions was 11.
．． After reaching 0.7.2, there was almost no change, and the treatment could be continued stably for about 1 month without producing abnormal scum or gel in either the first or second rinsing bath. . All printing results were also good.

〔Effect of the invention〕

According to the present invention, since no abnormal insoluble matter or gel is generated in the water washing bath after etching treatment, printing plates can be stably produced in large quantities by electrophotographic processes over a long period of time.

Representative Patent Attorney (8107) Kiyotaka Sasaki (and 3 others) Procedural amendment 1. Display of incident 1986-4 - Title of invention of Patent Application No. 166850 Plate making method for lithographic printing plates 3. Older people who make corrections Relationship to the case: Patent applicant

Claims (2)

[Claims] (1) In 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, the lithographic printing plate is rinsed after removing the non-image area. 1. A method for making a lithographic printing plate, characterized in that rinsing is carried out in a plurality of rinsing baths, and the pH of the rinsing baths is made lower toward later stages. (2) The plate-making method according to claim (1), wherein the pH of the initial rinsing bath is 10 to 13, and the pH of the final rinsing bath is 3 to 9.