JPS6223044A - Processing method of photosensitive lithographic printing plate - Google Patents

Abstract

PURPOSE:To process a negative and a positive type photosensitive lithographic printing plate (PS plate) in parallel by using the same automatic developing machine and to produce no waste liquid by using a liquid developer correspond ing to the type of the PS plate and a dedicated desensitization for each type. CONSTITUTION:A light reflection sensor 18 discriminates between a positive and a negative PS plate to select a positive developer supply pump 8 or negative developer supply pump 11 through a control part 19 and also switch a flow passage changeover valve 12. Then when th PS plate is the positive type, the positive developer in a positive developer storage tank 6, etc., circulates through a developer processing tank 1 to develop the positive PS plate and when the PS plate is the negative type, the plate is developed with the negative developer in a negative developer storage rank 9. Then, the plate is not washed and processed in a desensitization processing tank 13 with dedicated desensitization from a positive desensitization storage tank 15 or negative desensitization tank 17. Consequently, the negative and positive type PS plates are processed in parallel by the same automatic developing machine, and the dedicated is used, so there is no decrease in processing ability and no waste liquid is produced.

Description

Detailed Description of the Invention [Industrial Field of Application 1] The present invention relates to a method for processing a photosensitive lithographic printing plate, and more specifically to a method for processing a photosensitive lithographic printing plate that does not include a water washing step between the development step and the desensitization step. The present invention relates to a method for processing a printing plate and/or a photosensitive lithographic printing plate.

[Prior art J] A single automatic processor is used to process negative-type photosensitive lithographic printing plates (hereinafter simply referred to as negative-type PS plates) and bond-type photosensitive lithographic printing plates (hereinafter simply referred to as bond-type PS plates). If this were to be done, it would be necessary to replace the developer each time depending on the type of 28 plates, resulting in a problem that the efficiency of the work would be significantly reduced. As a countermeasure to this, Japanese Utility Model Application No. 54-151401 discloses that a developer for a negative PS plate and a developer for a positive PS plate are stored in dedicated storage tanks, so that when the 28th plate is developed, it can be used for the 28th plate. A method is disclosed in which a printing plate is obtained by supplying a developer solution, performing development, and washing with water after development.

However, washing with water after development leads to wastage of water and is not preferable as it also causes problems of environmental pollution due to drainage water.Furthermore, the 28th plate after washing with water is subjected to a desensitizing process to protect the plate surface. I! (also referred to as fJpm), which is inefficient and has problems such as poor ink receptivity of the resulting printing plate.

JP-A-54-800 is a development process that eliminates the water washing process.
No. 2 discloses a method in which a 28th plate is desensitized immediately after development. In this method, a desensitizing chemical liquid is supplied from a nozzle to the 28 plates that have passed through the development zone, but the excess liquid is collected and recycled for reuse.
The developer, etc. adhering to the 8th plate is gradually carried into the desensitizing solution and fatigues the solution. ! The fluid had to be changed frequently.

[Problem to be solved by the invention 1: A method for processing 28 plates that can process a negative PS plate and a positive 28 plate in parallel and does not involve washing with water has never been developed before. However, according to the studies of the present inventors, it is possible to combine the above two methods, i.e., store the negative and positive developing solutions in separate storage tanks and wait for development. If the 28-plate type is supplied and developed according to the mold, and then desensitized without washing with water, the desensitization will be greater than when either type of 28-plate is treated alone. It became clear that the fatigue of the processing solution increased significantly and that the solution had to be replaced more frequently. In addition, the printing plate thus obtained had low oil sensitivity in the image area, and the non-image area was insufficiently desensitized and was prone to scumming, making it impossible to obtain a good quality plate.

The object of the present invention is to produce negatives, molds 18 and 18 using the same automatic processor.
It is an object of the present invention to provide a method for processing 28 plates, which can process both types of 28 plates in parallel, and which does not generate waste water.

Another object of the present invention is to produce two types of negative and 28 plates and both positive and negative types.
To provide a processing method for a 28th plate, which can desensitize the 8th plate in good condition and sufficiently desensitize the non-image area without reducing the oil sensitivity of the image area. Another object of the present invention is that even when processing a negative Ps plate and a 28-bottom plate in parallel, the processing capacity of the desensitizing solution is minimized and the production process associated with replacing the desensitizing solution is reduced. The purpose of this invention is to provide a method for processing the 28th edition with improved performance.

Means for Solving Problem E] As a result of intensive research to solve the above problem, the present inventors have developed a method for automatically producing negative and/or positive photosensitive lithographic printing plates using an automatic developing machine. Depending on the type of photosensitive lithographic printing plate to be processed, a negative-working or positive-working photosensitive material is transported to the developing zone of the automatic processor and stored in a separate developer storage tank for circulation use. A dedicated developer for lithographic printing plates is supplied to the photosensitive lithographic printing plate surface for development processing, and then a dedicated desensitizing treatment solution is circulated to the plate surface according to the type of the photosensitive lithographic printing plate, and the above-mentioned It has been found that the above object can be achieved by a method for processing a photosensitive lithographic printing plate, which is characterized in that desensitization treatment is carried out in the same desensitization treatment tank of an automatic processor.

In the method of the present invention, the desensitizing treatment liquid for the negative PS plate and the positive 18 plate are separately separated and dedicated, so the same desensitizing liquid is used for the 28 plates of different types as described above. The desensitizing ability can be stably carried out over a long period of time without the sudden drop in desensitizing ability that occurs when the desensitizing solution is used repeatedly.

The present invention will be specifically explained below.

The 28th plate targeted by the present invention is one in which a photosensitive layer whose solubility changes by light irradiation is coated on a support, or a soluble layer in which an image resist layer can be set by an electrophotographic method or the like. It is provided on a support.

Supports used for the above 28 editions include paper, plastics (e.g. polyethylene, polypropylene, polystyrene, etc.), laminated paper, aluminum (including aluminum alloys), metal plates such as zinc, copper, etc., diacetic acid. Films of plastics such as cellulose, cellulose triacetate, cellulose propionate, polyethylene terephthalate, polyethylene polypropylene, polycarbonate, polyvinyl acetal, etc., paper or plastic films laminated or vapor-deposited with the above metals, aluminum or chrome plated. Among these, in particular,
Aluminum and aluminum-coated composite supports are preferred.

Further, the surface of the aluminum material is preferably roughened for the purpose of increasing water retention and improving adhesion with the photosensitive layer.

Examples of surface roughening methods include generally known methods such as brush polishing, ball polishing, electrolytic etching, chemical etching, liquid honing, sandblasting, etc., and combinations thereof, preferably brush polishing, electrolytic etching, and chemical etching. These include target etching and liquid honing.
Among these, surface roughening methods involving the use of electrolytic etching are particularly preferred.

The electrolytic bath used in electrolytic etching is an aqueous solution containing an acid, an alkali, or a salt thereof, or an aqueous solution containing an organic solvent. Liquid is preferred.

Further, the roughened aluminum plate is desmutted with an acid or alkali aqueous solution, if necessary.

The aluminum plate thus obtained is desirably anodized, particularly preferably with sulfur 1! I! Another method is treatment with a solution containing phosphoric acid.

Furthermore, if necessary, surface treatment such as pore sealing treatment and immersion in an aqueous solution of potassium zirconate can be performed.

The photosensitive composition of the PS plate used in the present invention contains a photosensitive substance as an essential component, and the physical and chemical properties of the photosensitive substance do not change upon exposure or subsequent development treatment. For example, there are differences in solubility in developing solutions due to exposure, differences in intermolecular adhesive strength before and after exposure, differences in affinity for water and oil due to exposure or subsequent development, and A material that can form an image area by electrophotography can be used.

Typical photosensitive substances include, for example, photosensitive diazo compounds, photosensitive azide compounds, compounds with ethylenically unsaturated double bonds, epoxy compounds that polymerize with acid catalysts, and C-0- that decomposes with acids. Examples include compounds having a C-group.

Examples of the photosensitive diazo compound include an 0-quinonenoasite compound which is a bot-type compound that becomes alkali-soluble upon exposure, and an aromatic diazonium salt which is a negative-type compound whose solubility decreases upon exposure.

Specific examples of 0-quinonenoasite compounds include, for example, Japanese Patent Application Publication Nos. 47-5303, 48-63802, and 48
-63803, 49-38701, 56-10
No. 44, No. 56-1045.

Special Publication No. 41-11222, No. 43-28403, No. 45-9610.

Publications No. 49-17481, U.S. Patent No. 2,797
, No. 213, $3,046,120, No. 3.188,
No. 210, No. 3,454,400.

No. 3,544,323, No. 3,573.917, No. 3,674,495.

No. 3,785,825, British Patent No. 1,277.6
No. 02, No. 1.251,345, No. 1,267.
No. 005, No. 1, No. 329, No. 888, No. 1.3
30.932, German Patent Nos. 1854 and 890, etc., and the present invention can be applied to PS plates using these compounds alone or in combination as photosensitive components. It can be preferably applied.

These photosensitive components include 0-quinone diat sulfonic acid ester or 0-quinone diazide carboxylic acid ester of an aromatic hydroxy compound, and 0-quinone diat sulfone #! of an aromatic amino compound. ! or 0-quinonediatcarboxylic acid amide, and these 0
It includes those in which the -quinonenoanodo compound is used alone, and those in which it is mixed with an alkali-soluble resin and this mixture is provided as a photosensitive layer.

The alkali-soluble resin includes a novolac type phenol resin, and specifically includes a phenol formaldehyde resin, a cresol formaldehyde resin, a phenol-cresol mixed formaldehyde resin, a cresol xylenol mixed formaldehyde resin, and the like.

Furthermore, as described in JP-A-50-125806, tert-
A combination of a phenol substituted with an alkyl group having 3 to 8 carbon atoms, such as butylphenol formaldehyde resin, or a condensate of cresol and formaldehyde can be used.

If necessary, additives such as dyes, plasticizers, and components imparting printout performance can be added to the photosensitive layer containing the 0-quinonenoanodo compound as a photosensitive component.

The amount per unit area of the photosensitive layer containing the 0-quinone di7odo compound as a photosensitive component is at least about 0.5 to 7 g/
The present invention can be applied to the following ranges.

There is no particular need to change the image exposure of the 18th printing plate to which the method of the present invention is applied, and a conventional method may be used.

A typical photosensitive component of the negative photosensitive layer is a diazo compound, for example, a diazo resin which is a condensate of diazonium salt and/or p-diazophenyl 7mine and formaldehyde, as described in Japanese Patent Publication No. 7364/1983. 7-enol salt or fluorocaprate of p-diazodiphenylamine described, 3-notoxydiphenylamine-4- described in Japanese Patent Publication No. 49-48001;
Diazo resin consisting of an organic solvent soluble salt of a copolycondensate of noazonium chloride, 4-nitronophenylamine and formaldehyde, 2-methoxy-4- of a condensate of p-diazodiphenyl7mine and formalderhyde Examples include human axy-5 benzoylbenzenesulfonate, tetrafluoro a borate of a condensate of p-diazophenyl 7mine and formaldehyde, and hexafluorophosphate.

The present invention can also be preferably applied to a negative type 28 plate containing these as photosensitive components.

In addition to those using these diazo compounds alone, the present invention can also be applied to those used in combination with various resins in order to improve the physical properties of the photosensitive layer.

Examples of such resins include shellac, derivatives of polyvinyl alcohol, copolymers often having alcoholic hydroxyl groups as described in JP-A-50-118802, and copolymers often having alcoholic hydroxyl groups as described in JP-A-55-155355. Examples include copolymers having phenolic hydroxyl groups frequently described.

These resins include copolymers containing at least 50% by weight of structural units represented by the following general formula;
R1 Director-(C1,-C)-Exposed C0O-(CH2Cl(O)n-H (wherein, R1 represents a hydrogen atom or a methyl group, and R2 represents a hydrogen atom, a methyl group, an ethyl group, or a chloromethyl group) , 11 is an integer of 1 to 10) and 1 to 80 mol% of a monomer unit having an aromatic hydroxyl group, and 5 to 90 mol% of an acrylic ester and/or methacrylic ester monomer unit. However, polymer compounds having an acid value of 10 to 200 are included.

The photosensitive layer of the negative 23rd plate to which the processing method of the present invention is applied can further contain additives such as dyes, plasticizers, components that provide printout performance, and the like.

m-plane M of the photosensitive layer! ! The amount per % is at least 0.
The present invention can be applied to a range of 1 to 7 g/m2.

There is no particular need to change the image exposure of the negative 28 plate processed by the processing method of the present invention, and a conventional method may be used.

The developer used in the present invention is preferably an aqueous alkaline developer. Among the aqueous alkaline developers, for the negative 28 plate which uses a diazo compound or the like as a photosensitive material, alkaline agents, organic solvents, anionic surfactants, etc. Agents, sulfites, etc. impregnated with water as a solvent are used.

Examples of alkaline agents include sodium silicate, potassium silicate, sodium hydroxide, lithium hydroxide, trisodium phosphate, sodium diphosphate, potassium diphosphate, potassium diphosphate, N17 ammonium tertiary phosphate, and sodium diphosphate. Inorganic alkaline agents such as ammonium diphosphate, sodium metasilicate, sodium bicarbonate, sodium carbonate, potassium carbonate, ammonium carbonate, etc., organic alkaline agents such as mono-, di-, or triethanolamine and tetraflukylammonium hydroxide; Organic ammonium silicates and the like are useful.

Content of alkaline agent in developer composition (±0.0
It is suitable to use it in a range of 5 to 20 weight percent, more preferably 0.1 to 10 weight percent.

Ethylene glycol mono-7 enyl ether, benzyl alcohol, n-propyl alcohol, etc. are useful as organic solvents.

The content of organic solvent in developer solution 11 is 0.
．． A range of 5 to 15 weight percent is preferred, with a more preferred range of 1 to 5 weight percent.

As anionic surfactants, higher alcohols (Cs
-C22) Sulfuric ester salts [[For example, sodium salt of lauryl alcohol sulfate, sodium salt of octyl alcohol sulfate, ammonium salt of lauryl alcohol sulfate, rTeepol B
-81J (trade name, manufactured by Shell Chemical Co., Ltd.), 11<2f thorium furkyl sal 7 ethyl, aliphatic alcohol phosphate ester salts (e.g., sodium salt of cetyl alcohol phosphate ester, etc.), alkylaryl sulfonates (e.g., sodium salt of dodecylbenzenesulfonic acid, sodium salt of isopropylnaphthalenesulfonic acid, sodium salt of sinaphthalene disulfonic acid, sodium salt of metanitrobenzenesulfonic acid, etc.), sulfonic acid salts of alkylamides (e.g., C1tf13) CONCHzCH*SO3N
a), dibasic CH.

Examples include sulfonate salts of fatty acid esters (eg, sodium sulfosuccinate dioctyl ester, sodium sulfosuccinate dihexyl ester, etc.). Among these, sulfonate salts are particularly preferably used.

Sulfites have the tendency to dissolve water-insoluble diazo resins in aqueous solutions, and are particularly effective in developing 28 plates consisting of a photosensitive layer combined with a hydrophobic resin, resulting in stain-free printing even after a long period of time has passed since manufacture. You can make a version.

Useful sulfites include alkali metal salts such as sodium, potassium, and lithium, and alkaline earth metal salts such as magnesium.

On the other hand, for a positive PS plate having a photosensitive layer containing an O-quine/cyazide compound, the alkali agent was added at 0°1 to 30°C.
An aqueous solution containing 0.5 to 20% by weight, preferably 0.5 to 20% by weight, is used, and is usually used at a pH in the range of 9 to 13.

The following additives can be added to such a developer in order to further improve the developing performance. For example, JP-A-5
NaC11, KCIKBr described in Publication No. 8-75152
Neutral salts such as E described in JP-A-58-190952
Chelating agents such as DTA and NTA, JP-A-59-1213
[Co (old '1)1iC12, CoC described in Publication No. 36
j! Complexes such as z”611□0, JP-A-50-513
Heptanionic or amphoteric surfactants such as sodium flukylnaphthalene sulfonate and N-tetradecyl-N1N-nohydroxyethylbetaine described in Publication No. 24, U.S. Patent No. 43
Nonionic surfactants such as tetramethyldesynediol described in JP-A-55-95946, cathodic polymers such as methyl chloride quaternized product of 1)-trimethylaminomethylpolystyrene described in JP-A-55-95946;
Ampholytic polymer electrolytes such as copolymers of vinylbenzyltrimethylammonium chloride and sodium heptacrylate described in JP-A-56-1425289, JP-A-57-19
Reducing inorganic salts such as sodium sulfite described in Publication No. 295Z,
Inorganic lithium compounds such as lithium chloride described in JP-A No. 58-59444, organic lithium compounds such as lithium benzoate described in JP-A-50-34442, Si, Ti, etc. described in JP-A-59-75255. organometallic surfactants containing, organic boron compounds described in JP-A-59-84241, quaternary ammonium salts such as tetraalkylammonium oxides described in European Patent No. 101010, benzyl alcohol ethylene glycol monophenyl Examples include organic solvents such as ether.

Various conventionally known methods can be used to develop the image-exposed 28 plate using the developer described above. Specifically, a method of spraying a developer from a number of nozzles onto the image-exposed photosensitive layer of the 28th plate, a method of wiping the photosensitive layer of the 28th plate with a sponge moistened with a developer, and a method of wiping the photosensitive layer of the 28th plate with a sponge moistened with the developer.
Examples include a method of applying a current test solution to the surface of the photosensitive layer of the plate using a roller.

Further, after the developer is applied to the photosensitive layer of the 28th plate in this manner, the surface of the photosensitive layer can be lightly rubbed with a brush or the like. Development conditions may be determined as appropriate depending on the above-mentioned development method.

The developing solution is reused by circulating the above-mentioned negative developing solution and blank developing solution through respective paths within the automatic developing machine. At this time, the development of the 28th plate is carried out using a common developing tank of an automatic developing machine for both the 28th negative plate and the 23rd positive plate. Specifically, if the 28th plate is a negative 28th plate, in which the negative developer and positive developer are stored and developed in dedicated developer storage tanks, the negative developer is stored in a common development processing zone. In the case of a positive type 23 plate, a developer for a common development processing tank is supplied. A switching valve may be installed in the recovery path of the used developer so that the developer for negative and blanks can be returned to their original storage tanks.

As an example of the above-mentioned treatment process, for example,
The method described in JP-A-151401 can be mentioned.

In the present invention, it is necessary to identify the type of 28 plates in order to change the developer depending on the type of 28 plates to be processed.

There are two methods for identifying the type of 28 plates to be developed: an artificial method or an automatic method. Examples of the artificial method include a method of identifying by button operation. Automatic methods include, for example, optically measuring and identifying the optical density of the photosensitive layer or measuring the spectral absorption of the photosensitive layer, or electrically measuring the impedance of the photosensitive layer, or magnetically determining the optical density of the photosensitive layer. Examples include a method of reading a signal stored in a memory element such as a card, or a method of reading a signal stored in a bar code.

Furthermore, the developer replenisher may be replenished in response to exhaustion of the developer due to development processing of these 28 plates or absorption of carbon dioxide in the air. Various conventionally known developer replenishers can be used, and various conventionally known methods can be used to replenish the developer replenisher.

It is preferable to squeeze the lithographic printing plate obtained by developing in this way so that the amount of developer on the plate surface is reduced. The amount of liquid is 10 ts Q/+a
``It is preferable that the following.

The resulting lithographic printing plate is then desensitized.

The desensitizing treatment has the purpose of desensitizing the non-image area and protecting the image area and the non-image area.

The desensitizing liquid used in the desensitizing process is mainly composed of a hydrophilic polymer, and the hydrophilic polymer is preferably a water-soluble resin with film-forming ability, such as dextrin,
gum arabic, alginates such as sodium alginate, water-soluble celluloses such as carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, water-soluble copolymers containing acrylamide units, vinyl methyl ether and anhydrous Examples include copolymers with maleic acid, copolymers with vinyl acetate and maleic anhydride, and the like. Among these, particularly preferred are gum arabic, dextrin, polyvinylpyrrolidone,
Carboxymethyl cellulose, polyvinyl alcohol and dextrin are most preferred. These water-soluble polymer compounds can be used alone or in combination of two or more. The concentration of the water-soluble polymer compound can vary over a wide range, but is generally 5% by weight based on the total weight of the desensitizing solution.
It is used in an amount of up to 40% by weight, preferably 10 to 30% by weight.

Further, it is preferable to contain a lipophilic substance in the desensitization treatment. Any lipophilic substance may be used as long as it prevents a decrease in the oil sensitivity of the image area, but preferred lipophilic substances include lipophilic resins used as vehicles for lithographic printing inks. be. Specifically, novolac type phenol resins such as phenol formaldehyde O (fat, cresol formaldehyde 01 Jolt, t-butyl 7-ethyl formaldehyde IH fat, xylene resin made by condensing phenol and xylene with formaldehyde, phenol, mesitylene and formaldehyde) resin condensed with polyhydroxystyrene, brominated polyhydroxystyrene, cashew ester, esterified product of copolymer of styrene and maleic anhydride, melamine resin, alkyd resin, polyester resin, epoxy resin, rosin For example, hydrogenated rosin, modified rosin such as rosin ester, petroleum resin such as Giltonite, etc. are preferred. Among these, preferred are /borac type phenolic resin, xylene resin, polyhydroxystyrene, brominated polyhydroxy Styrene, cashew RHB, etc., preferably having a molecular weight of about 300 to about 20,000.Other preferred lipophilic substances include oleic acid, lauric acid, valeric acid, hexadialic acid, capric acid, mystylic acid. , organic carboxylic acids having 5 to 25 carbon atoms such as valmitic acid, castor oil, etc. These lipophilic substances can be used alone or in combination of two or more, and there are no particular restrictions on their concentration. However, it is generally used in the range of about 0.1 to about 10% by weight.These lipophilic substances may be dispersed and contained in the desensitizing treatment liquid in the form of fine solid particles. It is used by emulsifying and dispersing it in a suitable solvent (S
can be done.

Further, an acid can be contained in the desensitizing treatment liquid. Examples of the acids to be contained include inorganic acids such as phosphoric acid, pyrophosphoric acid, polyphosphoric acid, monosodium phosphate, boric acid, hydrochloric acid, sulfuric acid, and nitric acid, such as succinic acid, oxalic acid, citric acid, maleic acid, lactic acid, and 1]-toluene. PIi acids such as sulfonic acid and benzenesulfonic acid can be used, and these may be used alone or in combination.
The above are used in combination. Among these, phosphoric acid and succinic acid are particularly preferred because they have the effect of desensitizing the non-image areas of the lithographic printing plate.The amount of P& used is determined by the pn? ) is preferably used in an amount that is in the acidic range. More preferably, it is used in an amount such that 9H is in the range of about 1 to 5.

Further, when it is desired to take advantage of the desensitizing effect of the above-mentioned phosphoric acid or succinic acid, it is preferable to use it in an amount of about 0.1 to about 10% by weight based on the total weight of the desensitizing and processing solution.

Further, the desensitizing treatment liquid can contain a surfactant. Various surfactants can be used, such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters. , nonionic surfactants such as glycerin fatty acid esters, such as fatty acid salts, alkyl sulfate ester salts, alkylbenzenesulfonic acid [1], alkylnaphthalene sulfonates, dialkyl sulfosuccinate ester salts, alkyl phosphate ester salts, naphthalene sulfonic acid Formalin condensates, anionic surfactants such as polyoxyethylene alkyl sulfate salts, cationic surfactants such as alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and betaines such as alkylbetaines. Examples include amphoteric surfactants typified by surfactants. The surfactant is preferably used in an amount of about 0.0 to about 5% by weight based on the total weight of the desensitizing treatment.

Further, the desensitizing treatment liquid can contain a wetting agent. This allows the desensitizing treatment liquid to be imparted with the property of spreading appropriately over the plate surface of the lithographic printing plate. Preferred such wetting agents are polyhydric alcohols, and preferred specific examples include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, bentanol, hexylene glycol,
Tetraethylene glycol, polyethylene glycol,
nopropylene glycol, tripropylene glycol,
Examples include glycerin, sorbitol, and pentaerythritol. The wetting agent is preferably used in an amount of about 0.1 to about 5% by weight based on the total weight of the desensitizing solution.

Further, the desensitization treatment liquid may contain a water-soluble salt. Preferred water-soluble salts include alkali metal salts and ammonium salts, particularly preferred are acetic acid,
Included are water-soluble alkali metal and ammonium salts of acids such as molybdic acid, boric acid, nitric acid, sulfuric acid, phosphoric acid, and polyphosphoric acid.

Specifically, ammonium acetate, sodium acetate, potassium acetate, sodium molybdate, potassium molybutate, sodium borate, ammonium borate, lithium nitrate, sodium nitrate, potassium nitrate, dibasic F phosphate, tribasic sodium phosphate, dibasic phosphate. Examples include potassium, potassium triphosphate, ammonium triphosphate, and sodium polyphosphate. Such water-soluble salts can be used alone or in combination of two or more, and are preferably used in an amount of about 0.01 to about 5% based on the total weight of the desensitizing treatment liquid.

In the desensitization treatment method of the present invention, the lithographic printing plate obtained by development treatment is desensitized using the same desensitization treatment solution for negative and positive use, without going through a water washing process. It is co-supplied while being recycled and reused using a treatment tank.

Examples of the above-mentioned specific methods include the following methods. The negative desensitizing liquid and the positive desensitizing liquid are stored in dedicated desensitizing liquid storage tanks, and if the lithographic printing plate to be desensitized is a negative type, a common desensitizing liquid is used. Co-supply the anti-lipidizing treatment liquid for Negamma to the processing tank, and if the lithographic printing plate to be desensitized is a flat type, supply the desensitizing processing liquid for Hepono to the common desensitizing treatment tank. do. Further, these negative and positive desensitization processing solutions can be circulated and reused using the same desensitization tank by switching the circulation paths using a valve or the like.

Examples of methods for supplying the desensitizing liquid onto the planographic printing plate include spraying the desensitizing liquid from a nozzle or shower pipe, and applying the desensitizing liquid to the planographic printing plate using a sponge moistened with the desensitizing liquid. Methods such as wiping the plate surface of a lithographic printing plate, and applying a desensitizing treatment liquid to the plate surface of a lithographic printing plate using a roller or the like can be used to speed up the process.

Further, as the method for co-supplying the desensitizing treatment liquid, only one method may be used, or two or more methods may be used in combination. After or while co-applying the desensitizing treatment to the surface of the lithographic printing plate in this manner, the surface of the lithographic printing plate can be lightly rubbed with a rubbing member such as a brush. Further, these rubbing members and the desensitizing liquid storage tank stage may be integrated.

The desensitizing liquid for the negative PS plate and the positive 23rd plate used in the present invention may have the same composition or may have a separate dedicated composition depending on the properties of the PS plate. However, even when using the same composition, the liquid used for the negative type 18th plate and the liquid used for the Bonn type 25th plate are stored in separate storage M'M4 as described above, and the liquid used for the PS plate of a specific type is stored in separate storage M'M4. Use cyclically only for

If the best desensitizing liquid composition for each negative or positive PS plate is different, a dedicated liquid may be prepared and used for each.

Further, after the desensitization treatment, the coating amount of the desensitization treatment liquid applied to the plate surface of the lithographic printing plate is 0.00% by dry coating weight.
1 g/+ product 2 to 1.5 g/m'' is preferred.

Furthermore, a replenisher for the desensitizing solution can be replenished in response to a decrease in the amount of the desensitizing solution due to fatigue and/or carry-out.

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

Example 7 3 parts by weight of esterified product of toquinone 1.2-:/atto-5-sulfonyl chloride and resorcinol-benzaldehyde resin (as described in Example 1 of JP-A-56-1044), cresol 7 Boratsukuri I fat, 9
Weight parts and Victoria Pure Blue Boll (
A photosensitive solution was prepared by dissolving 0.12 parts by weight of dye (manufactured by Hodogaya Chemical Industry Co., Ltd.) in 100 parts by weight of methyl cellosolve.

A grained aluminum plate with a thickness of 0.3111 mm was anodized in sulfuric acid to form an oxide film of about 2.5 g/+n2, washed thoroughly and dried, and the above photosensitive solution was applied on it and dried. A positive type 28 plate having a photosensitive layer of 2.5 g/l112 was obtained.

Also, a copolymer of parahydroxy 7-ninyl methacrylamide, acrylonitrile, ethyl acrylate, and methacrylic acid (molar ratio is 8.5:24:60 in the above order).
．． 5.0 parts by weight Hexafluorophosphate of a condensate of P-diazodine 7-yonylamine and paraform fluorite 0.5 parts by weight Biatoria vinyl blue boil (manufactured by Hodogaya Chemical Co., Ltd.) 0 A photosensitive liquid was prepared by dissolving .1 part by weight in 100 parts by weight of methyl cellosolve. Next, a grained aluminum plate with a thickness of 0.24I6IIl was anodized in sulfuric acid, and approximately 2g/m2
After forming an oxide film and washing thoroughly, the photosensitive solution having the above composition was applied onto the support obtained by immersing it in a +7um aqueous solution, thoroughly washing with water, and drying it, and dried it to give about 1.8 g. A negative PS plate having a photosensitive layer of /@2 was obtained.

The Bonn type and negative type PS plates obtained in this way were
A large number of sheets cut to a size of 003X 800ml11 were prepared.

The positive type 18 plate was then exposed through a transparency for 60 seconds from a distance of 80 cm using a 2 kHz metal halide lamp. In addition, the negative type 23 plate was exposed for 30 seconds under the same conditions through a transparent negative.

On the other hand, a potassium silicon aqueous solution (SiO = content 26% by weight, K20
Content: 13% by weight), potassium hydroxide aqueous solution@(48% by weight)
Aqueous solution) and pure water were used to prepare SiO□ with a molar ratio of O ((Si02)/(K2O)) of 1.78 and 20
A developing solution with a molar concentration of 3.90 mol/Q and a molar ratio of silicic acid to potassium (20 to 5i027) of 0.8
A developer replenisher with a molar concentration of 8, K, 0 of 7.78 mol/Q is used as il! i! I did it.

Furthermore, a developer having the following composition was prepared as a developer for a negative PS plate.

Ethylene glycol monophenyl ether 40 parts by weight Jetanolamine 10 parts by weight Sodium 11-butylnaphthalenesulfonate 12 parts by weight Antifoaming agent (SN-5512 Toray Silicone Co., Ltd. N) 0
．． 05 parts by weight Water 937 parts by weight Furthermore, in FIG. 1, the automatic developing machine shown in FIG. , 6 is a positive developer storage tank, 6' is a bottom developer replenisher storage tank, 7 is a positive shower pipe, 8 is a positive developer pump, 8' is a positive developer replenisher pump, 9 is a negative developer storage tank,
10 is a negative shower pipe, 11 is a negative developer pump, and 12 is a flow path switching valve. 13 is a desensitization treatment tank;
Reference numeral 14 denotes a pump for desensitizing treatment liquid for hair, 15 denotes a storage tank for desensitizing treatment for hair, 16 denotes a pump for desensitizing treatment liquid for negatives, and 17 denotes a storage tank for desensitizing treatment liquid for negatives. Reference numeral 18 is a light reflection sensor for identifying the type of PS plate to be processed. Reference numeral 19 is a control device for controlling the operating flow path switching valve of the pump based on the type information.

Example 1 40Q each of the negative developing solution and BON developing solution were charged into the corresponding developer storage aMI of the automatic processor, and 30Q of the developer replenisher was charged into the developer replenishing solution storage tank. Further, 15Q of a desensitizing liquid (^) having the following composition was charged into the desensitizing liquid storage tank 15.

Desensitizing liquid (＾) 7 Labyrinth 7〃mu 4 parts by weight Dextrin 16〃85% phosphoric acid
0.3 Citric acid
2 〃96% Sodium Hydroxide 0
．． 1# water
100 Sodium nolauryl sulfosuccinate 2 7K 172 *Diethylene nonyl 7 alcohol ether 1
〃 Sorbitan fatty acid ester 1 〃Dioctyl azelate 2 〃Oleic acid
1. Furthermore, 15Q of the desensitizing liquid (B) having the following composition was charged into the desensitizing liquid storage tank 17.

Desensitizing liquid (B) Dextrin 200 parts by weight Methyl cellulose 5 Isopropylnaphthalene sulfonic acid Sorg 6 Gum arabic 1 Phosphoric acid
0.6 water
784 In addition, the temperature of the developer was kept at 25° C. for both negative and positive samples, and the development time was set to 40 seconds.

In addition, 21 m of positive developer replenisher is used for each development process.
(1 replenishment, 35m per hour regardless of development process)
It is now replenished at the rate of Q.

The desensitizing treatment liquid (^) was used to desensitize positive-working lithographic printing plates, and the desensitizing liquid ([1]) was used to desensitize negative-working lithographic printing plates. The selection of the developer desensitizing solution (^) or (B) for negative or positive use is performed by the control device 19 based on the product type information from the light reflection sensor 18. Further, the control device 19 controls the developer co-supply pumps 8, 11. Desensitized common feed pump 14.16
, control of the operation of the developer replenisher pump 8' and the switching valve 1
2 switching is controlled.

In this way, the exposed negative 18 plates and positive PS plates were processed in random order for a total of 250 plates, 125 plates each.
, but 50. Too, 150, 200, 250th edition Boy type PS version processed, 49, 99, 149, 199,
249. The grain of the board was processed using a negative 18th plate.

When a total of 10 negative planographic printing plates and positive planographic printing plates treated in each of these 50 plates were printed on a printing machine, the ink receptivity in the image area was good. The ink was transferred to the paper. Furthermore, the desensitizing effect of the non-image area was not impaired, and no scumming occurred at all, making it possible to obtain excellent printed matter.

Example 2 Desensitization treatment! The same treatment as in Example 1 was carried out using only (B). That is, the desensitization treatment liquid storage tanks 15 and 11
7. Fill both with desensitizing treatment liquid (B) and process 28.
If the plate is a positive type, the desensitization treatment (B) charged in the storage tank 15 is recycled and reused, and if the plate is a negative type, the desensitization treatment II solution (B) charged in the storage tank 17 is recycled and reused. Then, the plate surface was desensitized. Desensitizing treatment liquid (B)
15 plates each were placed in storage tanks 15 and 17, and 18 negative plates and 125 positive plates (P'4) were processed in random order in the same manner as in Example 1, for a total of 250 plates.
Similar results were obtained.

Comparative Example Desensitizing treatment liquid storage [5]
The same procedure as in Example 2 was carried out using only B).

That is, irrespective of whether the 28 plates to be treated are negative type or positive type, the desensitizing treatment 1 (B) charged in the desensitizing treatment liquid storage tank 15 is circulated and reused to desensitize the plate surface. I did it like that. Store the desensitizing solution (B) in tank 1.
Similarly to Example 2, 18 negative plates and 100 positive PS plates were processed in random order for a total of 200 plates. Thereafter, when the 200th edition grained round lithographic printing plate was printed on a printing machine, scumming occurred in the non-image area, making it unusable for practical use.

〔Effect of the invention〕

According to the present invention, 28 plates of both negative and positive types are arbitrarily mixed and processed using the same automatic developing machine, and the ink adhesion in the image area is good and the non-image area is insensitive and non-greasy, without producing washing waste water. It became possible to obtain a good lithographic printing plate.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an automatic processor suitable for the method of the present invention, which was used in the above embodiments.

Claims (1)

[Claims] A negative-working photosensitive lithographic printing plate and/or a positive-working photosensitive lithographic printing plate are automatically conveyed using an automatic developing machine, and in the development zone of the automatic developing machine, the pattern of the photosensitive lithographic printing plate to be processed is A special developer for negative or positive photosensitive lithographic printing plates, which is stored in separate developer storage tanks and used for circulation, is supplied to the photosensitive lithographic printing plate surface for development processing, and then The plate surface is characterized by circulating and supplying a desensitizing treatment liquid dedicated to each type of photosensitive lithographic printing plate, and performing the desensitization treatment in the same desensitization treatment tank of the automatic developing machine. Method of processing photosensitive lithographic printing plates.