JPS6221152A - Processing method for photosensitive lithographic printing plate - Google Patents

Abstract

PURPOSE:To process negative and positive type photosensitive lithographic printing plates (PS plate) by using the same automatic developing machine by supplying a developing soln. to be exclusively used for the PS plates of both types and to be cyclically used to the surfaces of the photosensitive lithographic printing plates to develop the plates then supplying an unused desensitizing liquid to the plate surfaces to desensitize the plates surfaces. CONSTITUTION:A common development process zone of the automatic developing machine for both the negative type PS plate and positive type PS plate is used for a developing process tank for the PS plates in the stage of cyclically using the developing soln. for negative and developing soln. for positive. A selector valve is provided to a recovering route for the used developing soln. so that the developing solns. for negative and positive are returned to the respective original storage tanks. The resulted lithographic printing plate in then subjected to the desensitization process. The desensitization process is intended to desensitize the non-image part and to protect the image part and non-image part. The desensitization processing soln. to be used for the desensitization process essentially consists of a hydrophilic high polymer and the unused desensitization processing soln. is required to be supplied onto the developed lithographic printing plate at every process. The used desensitization processing soln. is recovered and is subjected to a waste liquid treatment.

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 positive photosensitive lithographic printing plate.

[Conventional technology 1 Let's process a negative photosensitive lithographic printing plate (hereinafter simply referred to as negative 28 plate) and a positive photosensitive lithographic printing plate (hereinafter simply referred to as Bonn type PS plate) using one automatic processor. In this case, it becomes necessary to replace the developing solution each time depending on the type of 28 plates, which causes the problem that the efficiency of the work decreases as before. As a countermeasure to this, Japanese Utility Model Application No. 54-151401 discloses that a developing solution for the negative 23rd plate and a developing solution for the positive PS plate are each stored in dedicated storage tanks, and when the 28th plate is developed, the developer is 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 waste of water and also causes problems of environmental pollution due to wastewater, which is not preferable. Furthermore, the 28th plate after washing with water needs to be subjected to a desensitizing process (also called mulching) to protect the plate surface, which is inefficient and has problems such as poor ink receptivity of the resulting printing plate. Ta.

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 solution is supplied from a nozzle to the 28th plate that has passed through the development zone, but since the excess liquid is collected and recycled for reuse, the developing solution attached to the 28th plate is removed from the desensitized solution. The desensitizing fluid had to be replaced frequently because it was gradually carried inside and fatigued the fluid.

The method of processing the 28th plate that can process the negative type PS plate and the positive type 18th plate in parallel and does not involve water washing has never been seen before (its development is extremely desirable for practical use). However, according to the studies of the present inventors, a combination of the above two methods, i.e., depending on the 28-plate mold, in which the negative and positive developers are stored in separate storage tanks and subjected to development processing. When supplied, developed, and then desensitized without washing with water, fatigue of the desensitizing solution increases significantly compared to when 28 plates of either type are processed alone. It became clear that the liquid had to be replaced more frequently.Also, the printing plate obtained in this way had low oil sensitivity in the image area, and the non-image area was insufficiently desensitized, resulting in scumming. It became easy to get it and I couldn't get anything of good quality.

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

Another object of the present invention is to produce a negative type PS plate and a positive type 28
To provide a method for processing a 28-plate by desensitizing the plate in good condition and sufficiently desensitizing the non-image area without reducing the oil sensitivity of the image area. Another object of the present invention is to provide a 28-plate processing method that improves the complexity of the work involved in replacing the desensitizing solution.

[Means for Solving the Problems 1] As a result of intensive research to solve the above-mentioned problems, the present inventors have developed a negative type and/* or positive type photosensitive lithographic printing plate using an automatic developing machine. Depending on the type of photosensitive lithographic printing plate to be processed, negative type or positive type is stored and circulated in separate developer storage tanks in the development zone of the automatic processor. It is characterized by supplying a special developer for photosensitive lithographic printing plates to the surface of the photosensitive lithographic printing plate for development processing, and then supplying an unused desensitizing solution to the plate surface for desensitizing processing. It has been found that the above objects can be achieved by a method of processing photosensitive lithographic printing plates.

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 imager renost 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 metals such as those mentioned above, aluminum minilam. Alternatively, a copper plate plated with chrome may be mentioned, and among these, aluminum and a composite support coated with aluminum are particularly preferable.

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 may be an aqueous solution containing an acid, an alkali, or a salt thereof, or an aqueous solution containing an organic solvent.

Of these, particularly preferred are electrolytic solutions containing hydrochloric acid, nitric acid, or salts thereof.

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

It is desirable that the aluminum plate thus obtained be anodized, particularly preferably treated with a solution containing sulfuric acid or phosphoric acid.

Furthermore, if necessary, a sealing treatment and other surface treatments such as immersion in a potassium fluorozirconate aqueous solution can be performed.

The 28th edition photosensitive composition 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-〇- that decomposes with acids. Examples include compounds having a C-group.

Examples of photosensitive diazo compounds include 0-quinonenoanodo compounds, which are positive types that change to be alkali-soluble when exposed to light, and aromatic diazonium salts, which are negative types, whose solubility decreases when exposed to light.

Specific examples of 0-quinonediazide compounds include, for example, JP-A-47-5303, JP-A-48-63802, and JP-A-48.
-63803, 49-38701, 56-IQ
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
, 213, No. 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,
330, 932, German Patent No. 854,890, etc., and the present invention applies to the 28th edition in which these compounds were used alone or in combination as photosensitive components. can be preferably applied.

These photosensitive components include O-quinone di7didosulfonic acid ester of aromatic hydroquine compound or 0-quinone di7
Nodocarboxylic acid esters, and 0-quinonediazide sulfonic acid or 0-quinonediazidecarboxylic acid amide of aromatic amino compounds are included, and these 0-quinonediat compounds are used alone, and mixed with an alkali-soluble resin, and this mixture is used. It includes those provided with as a photosensitive layer.

Alkali-soluble resins include novolac type 7-el resins, and specifically include phenol formaldehyde resins, cresol formaldehyde resins, phenol-cresol mixed formaldehyde resins, cresol xylenol mixed formaldehyde resins, 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 also be used.

If necessary, additives such as dyes, plasticizers, and components imparting printout performance can be added to the photosensitive layer containing the 0-quinone di7dide compound as a photosensitive component.

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

There is no particular need to change the image exposure of the positive type 25 plate to which the method of the present invention is applied, and a conventional method may be used.

Typical photosensitive components of negative photosensitive scraps are diazo compounds, such as diazo resins, which are condensates of diazonium salts and/or p-diazophenyl 7mine, and formfuldehyde; 72/-l salt or fluorocaprate of p-no7zonophenylnamine described in Japanese Patent Publication No. 49-48001, 3-methoxydi72nylamine-4-diazonium described in Japanese Patent Publication No. 49-48001 Kurorai 1/,! : Diazo resin consisting of an organic solvent soluble salt of a copolycondensate of 4-nitronophenylamine and formaldehyde, 2-methoxy-4-hydroxy-5benzoylbenzenesulfone of a condensate of p-diazodiphenylamine and formaldehyde Examples include acid salts, tetrafluoroborates of condensates of p-diazodiphenylamine and formaldehyde, hexafluorophosphates, and the like.

The present invention can also be preferably applied to a negative type PS 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 having an alcoholic hydroxyl group in the side chain described in JP-A-50-118802, and copolymers having an alcoholic hydroxyl group in the side chain described in JP-A-55-155355. Examples include copolymers having the described phenolic hydroxyl groups in their side chains.

These resins include copolymers containing at least 50% by weight of structural units represented by the following general formula;
R1 sign-(CH2-C)-COO(CH2CHO)n H (wherein, R represents a hydrogen atom or a methyl group, R2 represents a hydrogen atom, a methyl group, an ethyl group, or a chloromethyl group, and n is 1 ) and 1 to 80 mol% of monomer units having an aromatic hydroxyl group, and 5 to 90 mol% of acrylic ester and/or methacrylic ester monomer units, and 10 to 10 mol%. Includes polymer compounds with an acid value of 200.

The photosensitive layer of the black-type PS plate to which the processing method of the present invention is applied may further contain additives such as dyes, plasticizers, and components imparting printout performance.

The amount per unit area of the photosensitive layer is at least 0.1 to
The present invention can be applied to a range of 7 g/m2.

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

As the developer used in the present invention, an aqueous alkaline developer is preferable. Among the aqueous alkaline developers, for a Ne-type PS plate using a diazo compound or the like as a photosensitive substance, an alkaline agent, an organic solvent, a 7-ion type A surfactant, sulfite, etc. containing water as a solvent is used.

Examples of alkaline agents include sodium silicate, potassium silicate, sodium hydroxide, lithium hydroxide, tribasic sodium phosphate, dibasic sodium phosphate, tribasic potassium phosphate, dibasic potassium phosphate, tribasic ammonium phosphate, and dibasic sodium phosphate. 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 tetraalkylammonium hydroxide; Ammonium silicate and the like are useful.

The content of alkaline agent in the developer composition is 00OS
It is suitable to use in the range of ~20% by weight,
More preferably, it is 0.1 to 10 weight percent.

Useful organic solvents include ethylene glyfur monophenyl ether, benzyl alcohol, and n-propyl alcohol.

The content of the organic solvent in the developer composition 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 [e.g., sodium salt of lauryl alcohol sulfate, sodium salt of octyl alcohol sulfate, ammonium salt of uryl alcohol sulfate, rTeepol B-8
1J (trade name, manufactured by Shell Chemical Co., Ltd.), disodium alkyl sulfate, etc.], aliphatic alcohol phosphate ester salts (e.g., sodium salt of heptyl alcohol phosphate ester, etc.), alkylaryl sulfonates (
(e.g., sodium salt of dodecylbenzenesulfonic acid, sodium salt of isopropylnaphthalenesulfonic acid, sodium salt of sinapthaline disulfonic acid, sodium salt of metanitrobenzenesulfonic acid, etc.), sulfonic acid salts of alkylamides (e.g., C+ 7) 1aiCONCH2CH2SOJ
a), dibasic CH.

There are sulfonic acid salts of fatty acid esters (for example, sodium sulfosuccinate dioctyl ester, sodium sulfosuccinate cyhexyl ester, etc.). Among these, sulfonate salts are particularly preferably used.

Sulfite has the function of dissolving water-insoluble noazo resin in an aqueous solution, and in particular, in the development of 88 plates consisting of a photosensitive layer combined with a hydrophobic resin, printing plates that do not stain even after a long period of time have passed since manufacture. can be made.

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 type 18 plate having a photosensitive layer containing an 0-quinonediazide compound, the above alkaline agent was added at 0°1 to 30°C.
An aqueous solution containing PI (in the range of 9 to 13) is used, preferably 0.5 to 20 weight percent.

The following additives can be added to such a developer in order to further improve the developing performance. For example, JP-A-5
Nacl, 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
[C0(NI+3)@]CL'3 described in Publication No. 36
, complexes such as CoCl2.61120, JP-A-50-51
7-ionic or amphoteric surfactants such as sodium flukylnaphthalene sulfonate and N-tetradecyl-N1N-dihydra-xyethylbetaine described in US Pat. No. 324, US Pat.
Nonionic surfactants such as tetramethyldecynediol described in No. 374920, JP-A-55-95946
Cathonic polymers such as methyl chloride quaternized product of p-dimethylaminomethyl polystyrene described in the publication,
Ampholytic polymer electrolyte such as copolymer of vinylbenzyltrimethylammonium chloride and acrylic acid Sorg described in JP-A-56-142528, JP-A-57-192
Reducing inorganic salts such as sodium sulfite described in Japanese Patent Publication No. 952, non-fi +7 tium compounds such as lithium chloride described in Japanese Patent Publication No. 58-59444, organic lithium such as lithium benzoate described in Japanese Patent Publication No. 50-34442. Compounds, organometallic surfactants containing Si, Ti, etc. described in JP-A No. 59-75255, organic boron compounds described in JP-A-59-84241, European Patent No. 10101
Examples include quaternary ammonium salts such as catetraalkylammonium oxide described in the specification of No. 0, and organic solvents such as benol alcohol ethylene glycol monophenyl ether.

Various conventionally known methods can be used to develop the image-exposed 88 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 88th plate, a method of wiping the photosensitive layer of the 28th plate with a sponge moistened with a developer, and a method of exposing the 28th plate to light. Examples include a method of applying a developer to the surface of the layer using a roller.

Further, after the developer is applied to the photosensitive layer of the 88 plate in this manner, the surface of the photosensitive layer can be lightly rubbed with a brush or the like. The developing conditions may be appropriately determined depending on the above-mentioned developing method.

The developing solution is reused by circulating the aforementioned negative developing solution and positive developing solution through respective paths within the automatic developing machine. At this time, the developing processing tank for the 88th plate uses a common developing processing zone of the automatic processor for both the negative PS plate and the positive 18th plate. Specifically, the developer for negatives and the developer for positives are stored in dedicated developer storage 'iIL tanks, and if the 88 plate to be developed is a negative PS plate, the developer for negatives is stored in a common development processing zone. A developing solution is supplied, and in the case of a positive type 18 plate, a developing solution for a common development processing zone is supplied. A switching valve may be installed in the recovery path of the used developer so that the negative and positive developer 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 the 13th plate in order to switch the developer depending on the type of the 13th plate to be processed.

There are two methods for identifying the type of 13th plate 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.

Further, the developer replenisher may be replenished in response to exhaustion of the developer due to development processing of these 13 plates or absorption of carbon dioxide gas 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, and the development on the surface of the lithographic printing plate that remains after being squeezed is preferable. The amount of liquid is preferably 1 h (17 m2 or less).

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 desensitization treatment liquid used in the desensitization treatment 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 carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, polyvinyl alcohol, polyvinyl vicritone, polyacrylamide, water-soluble copolymers containing acrylamide units, vinyl methyl ether and Examples include a copolymer with maleic anhydride, a copolymer with vinyl acetate and maleic anhydride, and the like. Among these, particularly preferred are gum arabic, dextrin, polyvinylpyrrolidone,
Carboquine methyl cellulose, polyvinyl alcohol, and textrin 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.
-40% by weight, preferably 10-30% by weight.

Further, it is preferable to include 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, phenol formaldehyde resins, cresol formaldehyde resins, 7-volume phenolic resins such as t-methylphenol formaldehyde resins, xylene resins made by condensing phenol and xylene with formaldehyde, resins made by condensing phenol, mesitylene, and formaldehyde, and polyhydroxy resins. Modifications of styrene, 70% polyhydroxystyrene, Cassiny resin, partially esterified copolymers of styrene and maleic anhydride, melamine resins, alkyd resins, polyester resins, epoxy resins, rosins, such as water-added rosins, rosin esters, etc. Examples include rosins, petroleum resins such as giltnite, and the like. Among these, preferred are novolac type phenolic resin, xylene resin, polyhydroxystyrene, brominated polyhydroxystyrene, and cashew resin,
Other preferred lipophilic substances, particularly those with a molecular weight of about 300 to about 20,000, include those having carbon numbers such as oleic acid, lauric acid, valeric acid, /nilic acid, capric acid, mystylic acid, palmitic acid, etc. 5 to 25 organic carboxylic acids, castor oil, etc. These lipophilic substances can be used alone or in combination of two or more,
There is no particular limit to its concentration, but it is generally used in a range of about 0.1 to about 10% by weight. These lipophilic substances can be used, for example, by being dispersed in the desensitizing treatment liquid in the form of fine solid particles, or by being dissolved in an appropriate solvent and emulsified and dispersed.

Further, an acid can be contained in the desensitizing treatment liquid. The acids to be contained include, for example, phosphoric acid, pyrophosphoric acid, polyphosphoric acid, monophosphoric acid (17 um), inorganic acids such as boric acid, hydrochloric acid, sulfuric acid, and nitric acid, such as succinic acid, oxalic acid, citric acid, maleic acid, lactic acid, -) Organic acids such as luenesulfonic acid and benzenesulfonic acid can be used, and these can be used alone or in combination of two or more. Among these, phosphoric acid and succinic acid are particularly preferred since they have the effect of desensitizing the non-image areas of the lithographic printing plate. The amount of acid to be used is preferably such that the pH of the desensitizing treatment solution is in the acidic range. More preferably, it is used in an amount such that the pH is in the range of about 1-5.

In addition, if you want to take advantage of the desensitizing effect of phosphoric acid or succinic acid, approximately 0%
．． Preferably, it is used in a range of 1 to about 10% by weight.

Further, the desensitizing treatment liquid can contain a surfactant. Various surfactants can be used, such as polyoxyethylene 7-alkyl ether kyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, bilioxyethylene sorbitan fatty acid esters, and glycerin fatty acids. Nonionic surfactants such as esters, such as fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, nofurkyl sulfosuccinate ester salts, furkyl phosphate ester salts, naphthalene sulfonic acid formalin condensates, polyoxy 7-ionic surfactants such as ethylene alkyl sulfate salts, cationic surfactants such as alkyl 7-mine salts, quaternary ammonium salts, polyoxyethylene furkylamine salts, and betaine surfactants such as alkyl betaines. Representative amphoteric surfactants can be exemplified. The surfactant is preferably used in an amount of about 0.01 to about 5% by weight based on the total weight of the desensitizing solution.

Further, the desensitizing treatment liquid can contain a wetting agent. Due to this, insensible fat here J! It is possible to impart the characteristic that the Li liquid spreads 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,
Examples include triethylene glycol, propylene glycol, butylene glycol, bentanediol, hexylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, 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.

Furthermore, the desensitization treatment solution may contain a water-soluble salt. Preferred water-soluble salts include alkali metal salts and ammonium salts, and particularly preferred are water-soluble alkali metal salts and ammonium salts of acids such as acetic acid, molybdic acid, boric acid, nitric acid, sulfuric acid, phosphoric acid, and polyphosphoric acid. Contains 7 mm and 9 mm salt. Specifically, ammonium acetate, sodium acetate, potassium acetate, sodium molybutate,
Potassium molybdate, sodium borate, ammonium borate, lithium nitrate, sodium nitrate, potassium nitrate,
Examples include dibasic sodium phosphate, tribasic sodium phosphate, dibasic potassium phosphate, tribasic potassium phosphate, tribasic ammonium phosphate, and sodium polyphosphate. Such water-soluble salts can be used alone or in combination of two or more,
About 0.01 to about weight i5 based on the total weight of the unfattening treatment liquid
It is preferable to use it in the range of %.

In the desensitization method of the present invention, it is necessary to supply unused desensitization onto the currently cleaned lithographic printing plate each time the process is carried out. Since an unused desensitizing liquid is supplied every time the treatment Q is carried out, the desensitizing effect is constant and a good printing plate can always be obtained. In addition, the used desensitizing solution can be collected and disposed of as waste, eliminating the need for the complicated work of constantly paying attention to desensitizing treatment fatigue and replacing it as needed. be able to.

Here, the unused desensitization treatment refers to a desensitization treatment liquid that has not been used for desensitization treatment of a lithographic printing plate.

When supplying an unused desensitizing solution onto the 28th plate, the previously used desensitizing solution is partially parallelized with the unused desensitizing solution within a range that does not reduce the effectiveness of the unused desensitizing solution. It may also be supplied. For example, when there are multiple desensitizing liquid supply nozzles, unused desensitizing liquid is used as part of the desensitizing liquid to be supplied. One method is to supply the unused desensitizing solution to the remaining specific nozzles, but all the unused desensitizing solution supplied onto the lithographic printing plate is supplied with unused desensitizing solution. Most preferably, a liquid is used.

Examples of methods for supplying the desensitizing liquid onto the lithographic printing plate include spraying or dropping the desensitizing liquid from a nozzle or shower pipe, and applying the desensitizing liquid onto the lithographic printing plate using a sponge moistened with the desensitizing liquid. A method of wiping the plate surface, a method of applying a desensitizing treatment liquid to the plate surface of a lithographic printing plate using a roller, etc.
A method of supplying the desensitizing liquid by storing it in a narrow gap and passing the lithographic printing plate through it.The lithographic printing plate after desensitizing hangs down in a rod shape from the desensitizing liquid supply member due to surface tension. A method of supplying by contact, or a method of supplying by storing the desensitizing treatment liquid in a cylindrical object, creating a narrow gap on the side of the cylindrical object, and passing the lithographic printing plate through the gap. Examples include.

Further, as the method for supplying the desensitizing treatment liquid, only one method may be used, or two or more methods may be used in combination.

Further, when the desensitizer treatment liquid supplied by the supply means is not uniform on the plate surface, a means may be provided to make it uniform. Specifically, for example, a desensitizing liquid diffusion plate is provided that gradually approaches the lithographic printing plate transport path in the direction of transport of the lithographic printing plate, and the desensitizing liquid is supplied onto the lithographic printing plate from a nozzle or the like. is stretched. Examples include means to do so. The diffusion plate may be a flexible sheet-like material or a hard plate-like material.

Further, after or while supplying the desensitizing treatment liquid to the plate surface of the lithographic printing plate in this manner, it is preferable to lightly rub the plate surface of the lithographic printing plate with a rubbing member or the like. Specific methods of rubbing with a rubbing member include, for example, a method of rubbing by rotating a roller-shaped rubbing member, a method of rubbing by rotating a flat-plate-shaped rubbing member, or a method of rubbing by rotating a flat-plate-shaped rubbing member, or a method of rubbing by rotating a flat-plate-shaped rubbing member, or a method of rubbing by rotating a flat-plate-shaped rubbing member. Examples include a method of rubbing by moving a rubbing member, and a method of rubbing by moving a roller-shaped rubbing member or a planar-shaped rubbing member back and forth and/or left and right while rotating. Note that a plurality of these rubbing members may be used in combination. Examples of these rubbing members include brushes, sponges, and cloth.

Further, the desensitizing liquid supply means and the rubbing member may be integrated. For example, if the rubbing member is a disk-shaped brush and the desensitizing liquid supply means is a nozzle, the desensitizing liquid supply means and the rubbing member may be integrated. It is also possible to arrange the nozzle at the center of the rotation axis.

Further, in the present invention, a common desensitizing treatment liquid may be supplied to the negative planographic printing plate and the positive planographic printing plate, or a desensitization treatment liquid exclusively for each may be supplied.

If the best desensitizing treatment liquid for a negative planographic printing plate and a positive planographic printing plate is different, it is preferable to supply a dedicated desensitization treatment liquid to the corresponding plate.

The amount of the desensitizing treatment liquid supplied by the above means is always a constant amount for each treatment regardless of the size and type of the lithographic printing plate, or an amount corresponding to the area of the lithographic printing plate to be treated, or an amount corresponding to the area of the lithographic printing plate to be treated. Use an amount proportional to the length of the length or center of the lithographic printing plate.

The amount of the above-mentioned insensitizing oil treatment liquid per plate is Q10mQ/plate ~
The range is preferably 1000+u/plate, more preferably 2
0m! The range is from 1/plate to 200J/plate.

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/+2-1.5 g/+2 is preferred.

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

Example 7 Toquinone 1,2-noacyto-5-sulfonyl chloride and resorcinol-benzaldehyde ester (described in Example 1 of JP-A-56-1044)
3 parts by weight, cresol novolac resin, 9 parts by weight, and 0.12 parts by weight of Victoria Pure Blue BOH (dye manufactured by Hodogaya Chemical Industry Co., Ltd.) to 1 part by weight of methyl cellosolve.
00 parts by weight to make a photosensitive liquid. Thickness 0.3mm
A grained aluminum plate is anodized in sulfuric acid,
An oxide film of about 2.5 g/m2 was created, washed thoroughly and dried, and the above photosensitive solution was applied and dried to form an oxide film of about 2.5 g/m2.
A positive PS plate having 1112 photosensitive layers was obtained.

In addition, a copolymer of parahydroxy 7-ninyl methacrylamide, acrylonitrile, ethyl 7-acrylate, and methacrylic acid (molar ratio is 8, 5:24:60 in the above order)
．． 5.0 parts by weight Hexafluorophosphate of P-diazonophenylamine and paraformaldehyde condensate 0.5 parts by weight Viatria Pure Blue BOH (Hodokaya Chemical Industry Co., Ltd.)
A photosensitive solution was prepared by dissolving 0.1 part by weight of methyl cellosolve (manufactured by Co., Ltd.) in 100 parts by weight of methyl cellosolve. Next, a grained aluminum plate with a thickness of 0.24mm was anodized in sulfuric acid to form an oxide film of approximately 2g/112, washed thoroughly, and then silicate.) It was immersed in a 17um aqueous solution and rinsed thoroughly with water. A photosensitive solution having the above composition was coated on the support obtained by drying and dried, and about 1.
A negative type 18 plate having a photosensitive layer of 8 g/m2 was obtained. 100 copies of the 28 positive and negative plates obtained in this way
A large number of sheets cut to a size of 3 x 800 mm were prepared.

Next, the Bonmold 28 plate was exposed through a transparence for 60 seconds from a distance of 80 CO+ using a 2 to - metal halide lamp. In addition, the negative type 28 plate was exposed for 30 seconds under the same conditions through a transparent negative.

On the other hand, potassium silicate aqueous solution a (SiOz content 26% by weight, K.0
Using potassium hydroxide aqueous Q (48 wt% aqueous solution) and pure water, the molar ratio of SiO□ to 20 ((Si02)/(K2O)) was 1.7.
A developing solution with a molar concentration of 3.90 mol/Q and a molar ratio of silicic acid and potassium (SiO2/20
) is 0.88, and the molar concentration of K2O is 7.78 mol/Q.
A developer replenisher was prepared.

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 Noethanolamine 10 parts by weight Sodium n-butylnaphthalenesulfonate 12 parts Antifoaming agent (SN-5512 manufactured by Toray Silicone Co., Ltd.) 0
, 05 parts by weight Water 937 parts by weight In Fig. 1, the automatic developing machine shown in Fig. 1 was prepared.
is a development processing tank, 2 is a transport roller, 3 is a squeezing roller, 4 is a receiving roller, 5 is a brush roller, 6 is a positive developer storage tank, 6' is a positive developer replenisher storage tank, 7 is a positive developer storage tank 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, 12 is a flow path It is a switching valve. 13 is a desensitization treatment tank, 14 is a brush holder, and 15 is a disk-shaped brush that rotates and moves in the medial direction. 16 is a waste liquid storage tank, 17 and 19 are pumps for desensitizing processing liquid, and 18 and 20 are storage tanks for desensitizing processing liquid. Reference numeral 21 is a light reflection sensor that identifies the type of 18th edition to be processed, and 22 is a control device that controls the operating flow path switching valve of the pump based on the type information.

Example 1 The negative developing solution and the positive developing solution are as described above.

Pour 40 developer replenishers into the corresponding developer storage tanks of the dynamic developer, and add 30 developer replenishers into the developer replenisher storage tanks.
Q is included. Further, a desensitizing treatment liquid (^) having the following composition was charged into the desensitization treatment liquid storage tank 18 in a quantity of 25Q.

Gum arabic 4 parts by weight Dextrin 16 85% phosphoric acid
0.3 Citric acid
2496% sodium hydroxide 0.1 water
100 Sodium dilauryl sulfosuccinate 2 Polyoxyethylene noniphenyl ether 1 Sorbitan fatty acid ester 1 Dioctyl 7 gelate 2 Oleic acid
1 Mana, and a desensitizing treatment liquid (B) with the following composition:
A total of 259 of these were charged into the desensitization treatment liquid storage tank 20.

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, the positive developer replenisher is replenished every time one plate is developed, and is 35mQ per hour regardless of the development process.
It is now replenished at IW4.

The desensitizing treatment liquid (^) was used to desensitize positive-working planographic printing plates, and the desensitizing treatment liquid CB) was used to desensitize negative-working planographic printing plates.

In addition, 80 mQ of the desensitizing solution (^) and (B) was supplied onto the surface of the lithographic printing plate each time one plate was desensitized. The selection of these negative or positive developing solutions, desensitizing processing solutions (^) or (B) is made by the control device 22 based on the type information of the light reflection sensor 21.
I decided to do it with Further, the control device 22 controls the developer supply pumps 8, 11. Desensitizing liquid supply pump 17.19.
Control and switching valve port 1 for the operation of the developer replenisher pump 8'
2 switching is controlled.

In this way, the 28 exposed negative plates and the positive PS plates were processed in random order for a total of 500 plates, 250 plates each. However, for the 100th, 200th, 300th, 400th, and 500th editions, positive type 28th edition is processed, and 99th, 199th, 299th, 39th edition is processed.
9,499. The printing plate was processed using a negative type 28 plate. When a total of 10 winter-type lithographic printing plates and positive-type lithographic printing plates processed for each 100th edition were printed on a printing press, the ink receptivity in the image area was within 15 sheets for all 10 editions. The ink was completely 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 A treatment was carried out in the same manner as in Example 1 using only the desensitizing treatment liquid (B). That is, irrespective of whether the 23 plate to be processed is a negative type or a positive type, only the desensitizing treatment (B) charged in the desensitizing treatment liquid storage tank 20 is supplied to the needle surface of the lithographic printing plate. did. When the supply amount and other conditions were all the same as in Example 1, 28 negative plates and 28 positive plates were processed in random order, 250 plates each for a total of 500 plates, and the same results as in Example 1 were obtained.

Comparative Example Processing was carried out in the same manner as in Example 2 using an automatic processor equipped with the desensitizer processing device shown in FIG. 2 instead of the device used in the desensitization processing section of the automatic processor shown in FIG. did. In FIG. 2, 23 is a desensitizing tank, and 24 is a desensitizing liquid storage tank. The desensitization processing apparatus shown in FIG. 2 circulates and reuses the desensitization processing liquid, and this is carried out by a shower pipe that supplies the desensitization processing liquid onto the printing plate. Further, the supply amount of the desensitizing treatment liquid was set at IOQ/lll1n. In this manner, the desensitizing liquid (B) used in Example 2 was charged into the desensitizing liquid storage tank 24 in 409 minutes. The development processing section and development processing conditions were the same as in Example 2. In this way, as in Example 2, 28 negative plates and 28 positive plates were processed in random order, 150 plates each, for a total of 300 plates. After that, 3
The positive planographic printing plate processed on the 00th plate is put into the printing machine.

When it was printed over a wide range of colors, scumming occurred in the non-image area, making it unusable for practical use.

〔Effect of the invention〕

By the method of the present invention, by the same automatic processor,
By arbitrarily mixing 15 plates of both positive and negative types, it has become possible to stably obtain high-quality printing plates without generating waste water.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the automatic developing machine used in the embodiment of the present invention, and FIG. 2 is a schematic diagram of the desensitization processing section of the automatic developing machine used in the comparative example. Applicant: Konishi Roku Photo Industry Co., Ltd. Roku2°

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 A method for processing a photosensitive lithographic printing plate, characterized in that desensitization treatment is performed by supplying an unused desensitization liquid to the plate surface.