JPH08248643A - Lithographic form plate making method - Google Patents

Abstract

PURPOSE: To prevent the precipitated matters of a photopolymerizated layer and the precipitation of agar gel in developer for a long time by containing amphoteric surface active agent in at least either developer or developing replenisher. CONSTITUTION: A photosensitive lithographic form plate with a photopolymerized layer is developed by developer containing alkali silicate and developing deterioration due to the repeated use of the developer is compensated by resupplying developing replenisher containing alkali silicate. In this case, at least either the developer or developing replenisher contains amphoteric surface active agent. For the amphoteric surface active agent contained in alkaline developer containing alkali silicate or its replenisher, betaine type amphoteric surface active agent, glycine type amphoteric surface active agent, alanine type amphoteric surface active agent or sulfobetaine type amphoteric surface active agent may be used and two or more types of them can also be combined. For alkaline agent, sodium silicate, potassium silicate, lithium silicate, etc., can be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing plate making method in which a photosensitive lithographic printing plate having a photopolymerizable layer is developed with an alkaline developing solution containing an alkali silicate using an automatic processor.

[0002]

2. Description of the Related Art Conventionally, various methods have been proposed and used for developing a printing plate. For example, a method of removing the non-image area of the printing plate using an organic solvent such as isopropyl alcohol or butyl alcohol, or an inorganic alkali compound such as trisodium phosphate or an alkali metal salt is similarly dissolved and removed. It was known how to do it. However, the former has a problem that the organic solvent is relatively expensive and a part of the image area is dissolved and removed during development, so that a sufficient contrast between the non-image area and the image area cannot be secured. ing. On the other hand, even in the latter method, the support provided with the photosensitive layer may be eroded by trisodium phosphate, and in particular, considering that the support of this kind is made of aluminum, it is a serious problem. Is coming.

On the other hand, a photosensitive lithographic printing plate is desired to have high sensitivity, and a positive photosensitive lithographic printing plate comprising an o-quinonediazide compound and a negative photosensitive sensitizer containing a diazo compound as a photosensitive component, which have been most popular in the past. In addition to the lithographic printing plate, a photopolymerizable photosensitive lithographic printing plate of the type in which a latent image is formed by a free radical reaction by a combination of a photo free radical generator and an ethylenically unsaturated compound has been studied.

In this method, when a photosensitive lithographic printing plate having an image-exposed photopolymerizable layer is developed using an aqueous alkali silicate solution, a highly sensitive lithographic printing plate can be obtained. However, when the development processing of a large number of lithographic printing plates is repeated by a method of replenishing the development replenisher with an automatic processor and repeatedly using it, the photopolymerizable layer eluted in the developer of the automatic processor is deposited. I found out that

The photosensitive lithographic printing plate of the type in which a latent image is formed by the above-mentioned free radical reaction generally has excellent sensitivity, but has a drawback that the free radical reaction is inhibited by oxygen. It is known that it is effective to provide some kind of oxygen barrier layer on the photosensitive layer, and such an oxygen barrier layer containing polyvinyl alcohol as a main component is known to be effective. However, when a similar process is repeated by a method in which a photosensitive lithographic printing plate having an oxygen barrier layer containing polyvinyl alcohol as a main component on the photosensitive layer is repeatedly used by replenishing a developing replenisher with an automatic developing machine. It was also found that an agar-like gel was precipitated in the developing solution of the automatic processor.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is an alkaline developing solution containing an alkali silicate which is repeatedly used by replenishing a developing replenisher with an automatic developing machine and using a photosensitive layer having a photopolymerizable layer. To provide a method for developing a photosensitive lithographic printing plate which does not deposit a photopolymerizable layer precipitate or an agar-like gel in a developer for a long period of time by a method for developing a lithographic printing plate.

[0007]

[Means for Solving the Problems] As a result of various studies, the present inventors have reached the present invention. That is, the present invention is to develop a photosensitive lithographic printing plate having a photopolymerizable layer with a developer containing an alkali silicate, and replenish a developing replenisher containing an alkali silicate for deterioration of developability due to repeated use of the developer. The method of making a lithographic printing plate according to claim 1, wherein at least one of the developing solution and the developing replenisher contains an amphoteric surfactant.

As the amphoteric surfactant contained in the alkaline developer containing alkali silicate and its replenisher used in the present invention, there are betaine-type amphoteric surfactants, glycine-type amphoteric surfactants, alanine-type amphoteric surfactants, and sulfones. Any of the betaine-type amphoteric surfactants may be used, and two or more kinds may be used in combination. The betaine-type amphoteric surfactant generally has a structure represented by the following formula (1) in the molecule.

[0009]

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Specific examples include the following.

[0011]

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The glycine-type amphoteric surfactant generally has a structure represented by the following formula (2) in the molecule. —NH—CH ₂ —COOH (2) Specifically, there is a group of amphoteric soaps generally called TEGO as described below.

[0013]

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The alanine-type amphoteric surfactant generally has a structure represented by the following formula (3) in the molecule, and is an alkylalanine produced by hydrolyzing an addition reaction product of an alkylamine and an acrylic ester. Or its salt is common. _{-NH-CH 2 -CH 2 -COOH (} 3)

Most preferably used among these amphoteric surfactants is a group of alanine type amphoteric surfactants, and specific examples thereof include N-octdecyl-β-alanine (sodium salt) and N-mistyryl. Examples include -β-alanine (sodium salt), laurylaminopropionic acid (sodium salt), and Lipomin LA (manufactured by Lion Corporation). The amount of the amphoteric surfactant added to the developing solution or the developing replenishing solution is preferably 0.05 to 10% by weight, more preferably 0.03 to 5% by weight.

Examples of the alkaline agent contained in the alkaline developer containing alkali silicate and its replenisher used in the present invention include sodium silicate, potassium silicate, lithium silicate and the like, as well as sodium hydroxide, potassium hydroxide and water. Lithium oxide, ammonium hydroxide, sodium triphosphate, sodium diphosphate, potassium triphosphate, potassium diphosphate, ammonium triphosphate, ammonium diphosphate, sodium metasilicate, sodium bicarbonate, sodium carbonate, potassium carbonate , Inorganic alkali agents such as ammonium carbonate, monoethanolamine, diethanolamine, triethanolamine, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine Amine, n- butylamine, mono isopropanolamine, diisopropanolamine,
Organic amine compounds such as triisopropanolamine, ethyleneimine, and ethylenediimine can be used.

The alkaline developer containing alkali silicate and its replenisher used in the present invention preferably contain no organic solvent, but may contain 5% by weight or less of the following solvent if necessary. For example, carboxylic acid esters such as ethyl acetate, propyl acetate, butyl acetate, and levulinate; ketones such as ethyl butyl ketone, diisobutyl ketone, and methyl isobutyl ketone; ethylene glycol monobutyl ether, ethylene glycol benzyl ether, ethylene glycol monophenyl Alcohols such as ether, benzyl alcohol, methylphenylcarbinol, n-amyl alcohol, methylamyl alcohol; alkyl-substituted aromatic hydrocarbons such as xylene; halogenated hydrocarbons such as methylene dichloride and ethylene dichloride. Is mentioned. You may use 1 or more types of these organic solvents.

The alkaline developer containing alkali silicate and its replenisher used in the present invention may optionally contain a nonionic surfactant and / or an anionic surfactant.

Specific examples of such nonionic surfactants include polyoxyalkylene alkyl ethers and polyoxyalkylene alkyl phenyl ethers (eg, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, polyoxyethylene lauryl ether). , Polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, etc.), oxyethylene / oxypropylene block copolymer, polyethylene glycol, sorbitan fatty acid esters (For example, sorbitan monolaurate, sorbitan monostea , Sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan sesquioleate, sorbitan distearate, etc.), polyoxyethylene sorbitan fatty acid esters (eg, polyoxyethylene sorbitan monolaurate, polyoxyethylene) Sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, etc.), polyoxyethylene sorbitol fatty acid esters (tetraoleic acid polyoxyethylene sorbit, etc.), glycerin fatty acid Esters (eg, glycerol monostearate, glycerol monooleate, etc.), polyoxyethylene fatty acid esters (eg, Polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol monolaurate, polyethylene glycol monooleate, etc.), polyoxyethylene alkyl amines, polyoxyethylene hardened castor oil, alkyl alkanolamides, and the like.

As the anionic surfactant, fatty acid salts (for example, mixed fatty acid soda soap, semi-hardened tallow fatty acid sodium soap, sodium stearate soap, semi-hardened tallow fatty acid potassium soap, oleic acid potassium soap, castor oil potassium soap, etc.), Alkyl sulfate ester salts (eg, sodium lauryl sulfate, triethanolamine lauryl sulfate, ammonium lauryl sulfate, etc.), alkylbenzene sulfonates (eg, sodium dodecylbenzene sulfonate, etc.), alkylnaphthalene sulfonates (eg, sodium alkylnaphthalene sulfonate) Etc.), alkyl sulfosuccinates (eg, sodium dialkyl sulfosuccinate), alkyl diphenyl ether disulphonates (eg, alkyl diphenyl ether disulfone) Sodium, etc.), alkyl phosphates, polyoxyethylene alkyl (alkylaryl) sulfates, naphthalenesulfonic acid formalin condensates, polyoxyethylene alkyl phosphoric acid esters. The content of these nonionic and anionic surfactants is generally less than 10%, preferably less than 5%, more preferably 1%.
It is less than%.

The alkaline developer containing alkali silicate and its replenisher used in the present invention may contain an antifoaming agent, if necessary. Since this defoaming agent is selected for the purpose of suppressing foaming of the processing liquid used in the development and subsequent processing, various defoaming agents can be selected depending on the properties of the processing liquid. Is especially good. Examples of the silicone defoaming agent preferably used here include dimethyl silicone oil (viscosity 10
Up to 300,000 cSt), alkyl-modified silicone oil, silicone polyether copolymer, etc., but these are usually oils, solutions, emulsions,
It is commercially available as an oil compound and can be easily obtained. Among these, 1 type (s) or 2 or more types can be used together. The content of the defoaming agent is 1
It is preferably less than 0%, more preferably less than 1%. For the purpose of maintaining the foam-suppressing effect, generally, a replenisher of the developer contains a higher concentration of the defoamer than that of the developer, but the purpose is simply to defoam and suppress the foam during the production and transportation of the solution. If not, of course.

The automatic developing machine used in the present invention is preferably provided with a mechanism for automatically replenishing the developing bath with a required amount of the replenisher, and preferably a mechanism for discharging the developer exceeding a certain amount. It is preferably provided with a mechanism for automatically replenishing the developing bath with a required amount of water, preferably with a mechanism for detecting plate making, and preferably based on detection of plate making. Of the replenisher and / or water to be replenished based on the detection of plate passing and / or the estimation of the treated area. The mechanism for controlling the temperature of the developer is preferably added, and the pH of the developer is preferable.
And / or a mechanism for detecting electric conductivity is provided, and preferably the replenishing amount and / or the replenishing amount of the replenishing liquid and / or water to be replenished based on the pH and / or the electric conductivity of the developer is controlled. The mechanism to do is added.

The automatic processor used in the present invention may have a pretreatment section for immersing the plate in the pretreatment liquid before the developing step. The pretreatment section is preferably provided with a mechanism for spraying the pretreatment liquid on the plate surface, and is preferably provided with a mechanism for controlling the temperature of the pretreatment liquid to any temperature of 25 ° C to 55 ° C. Preferably, a mechanism for rubbing the plate surface with a roller brush is provided. Water is used as the pretreatment liquid.

The photosensitive lithographic printing plate having a photopolymerizable layer, which is the object of the developing method of the present invention, basically comprises at least a polymerizable unsaturated group on an aluminum plate having an anodized film as a support. And a photosensitive layer containing a photopolymerization initiator. Suitable aluminum plates include pure aluminum plates and aluminum alloy plates, as well as plastic films laminated or vapor deposited with aluminum. The surface of such an aluminum plate is provided with an aluminum oxide film by anodizing treatment, but it may be subjected to a graining treatment before that, or as described in JP-B-47-5125. After anodizing the plate,
Those obtained by immersion treatment in an aqueous solution of an alkali metal silicate are also preferably used. The anodizing treatment is carried out, for example, with an inorganic acid such as phosphoric acid, chromic acid, sulfuric acid or boric acid, an organic acid such as oxalic acid or sulfamic acid, or an aqueous solution of these salts, or an electric field obtained by combining two or more kinds of the aqueous solutions. It is carried out by passing an electric current in a liquid using an aluminum plate as an anode. Further, silicate electrodeposition as described in US Pat. No. 3,658,662 is also effective. Furthermore, U.S. Pat. No. 4,087,341, JP-B-46-27481, and JP-A-52-30503.
It is also useful to use the support, which has been subjected to the electric field graining as disclosed in Japanese Patent Laid-Open Publication No. 1994-A1, which is anodized as described above. Further preferred are aluminum plates which have been grained, chemically etched and then anodized as described in US Pat. No. 3,834,998. These hydrophilization treatments, in addition to the treatment for making the surface of the support hydrophilic, prevent harmful reaction with the photosensitive composition provided thereon, and further improve the adhesion to the photosensitive layer. It is applied for various purposes such as to improve

After further treatment, a water-soluble resin such as polyvinylphosphonic acid, a polymer or copolymer having a sulfonic acid group in the side chain, polyacrylic acid, a water-soluble metal salt (eg zinc borate). , Or a yellow dye,
An undercoat of an amine salt or the like is also suitable. A support in which an addition-reactive functional group containing an allyl group and an alkoxy group is bonded to the above-mentioned anodized aluminum plate is also useful.

The photosensitive layer provided on the substrate comprises a polymerizable compound having at least a polymerizable unsaturated bond and a photopolymerization initiator, and the polymerizable compound having at least a polymerizable unsaturated bond is a terminal ethylene. It is selected from compounds having at least one, and preferably two or more, sex unsaturated bonds. For example, it has a chemical form such as a monomer, a prepolymer, that is, a dimer, a trimer and an oligomer or a mixture thereof and a copolymer thereof. Examples of monomers and copolymers thereof include esters of unsaturated carboxylic acids (eg acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid) with aliphatic polyhydric alcohol compounds, and unsaturated Examples thereof include amides of carboxylic acids and aliphatic polyvalent amine compounds.

Specific examples of the monomer of the ester of the aliphatic polyhydric alcohol compound and the unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, and 1,3.
-Butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate 1,4-cyclohexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate. , So Bi penta acrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer.

Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol. Dimethacrylate, hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3- Methacryloxy-2-hi Rokishipuropokishi) phenyl] dimethyl methane, bis - [p- (acryloxy ethoxy)
Phenyl] dimethyl methane and the like.

The itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate,
There are 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate, sorbitol tetramethacrylate and the like. Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate. Examples of the isocrotonic acid ester include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate. The maleic acid ester includes ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, sorbitol tetramaleate and the like.
Furthermore, a mixture of the above-mentioned ester monomers can also be mentioned.

Specific examples of the amide monomer of an aliphatic polyvalent amine compound and an unsaturated carboxylic acid include methylenebis-acrylamide, methylenebis-methacrylamide, 1,6-hexamethylenebis-acrylamide, 1,6-hexa. Methylenebis-methacrylamide,
Examples include diethylenetriamine tris acrylamide, xylylene bis acrylamide, and xylylene bis methacrylamide. Other examples include Japanese Examined Patent Publication No. 48-417.
No. 08, the polyisocyanate compound having two or more isocyanate groups in one molecule is added with a vinyl monomer having a hydroxyl group represented by the following general formula (A) in one molecule. Examples thereof include vinyl urethane compounds containing a polymerizable vinyl group. CH ₂ ═C (R) COOCH ₂ CH (R ′) OH (A) (wherein R and R ′ represent H or CH ₃ ).

Further, urethane acrylates as described in JP-A-51-37193, JP-A-48-
No. 64183, Japanese Patent Publication No. 49-43191, Japanese Patent Publication No. 52
Examples thereof include polyfunctional acrylates and methacrylates such as polyester acrylates and epoxy acrylates obtained by reacting an epoxy resin with (meth) acrylic acid as described in JP-A-30490. Furthermore, Japan Adhesive Association magazine vol. 20, No. 7, 300-308
Those introduced as photocurable monomers and oligomers on page (1984) can also be used.
The amount of these components (i) used is 5 to 90% by weight (hereinafter abbreviated as%), preferably 10 to 70%, more preferably 15 based on the total components of the photopolymerizable composition.
~ 50%.

As the photopolymerization initiator, benzyl, benzoin, benzoin ether, Michler's ketone, anthraquinone, acridine, phenazine, benzophenone, 2
-Ethylanthraquinone, trihalomethyltriazine compounds, ketoxime esters, etc., and also certain photoreducible dyes described in US Pat. No. 2,850,445,
For example, Rose Bengal, Eosin, Erythrosin,
Alternatively, a system with a combination of dye and initiator, such as
Complex initiation system of dye and amine (Japanese Patent Publication No. 44-20189 etc.), hexaarylbiimidazole and radical generator and system of dye (Japanese Patent Publication No. 45-37377 etc.),
Hexaarylbiimidazole and p-dialkylaminobenzylidene ketone system (Japanese Patent Publication No. 47-2528, Japanese Patent Publication No. 54-155292, etc.), dye and organic peroxide system (Japanese Patent Publication No. 62-1641, Japanese Patent Publication No. 62-1641) Sho 59-1504
JP-A-59-140203, JP-A-59-189
340, U.S. Pat. No. 4,766,055, JP-A-6
2-174203), a system of a dye and an active halogen compound (JP-A-54-15102, JP-A-58-155).
03, JP-A-63-178105, JP-A-63-2
58903, JP-A-2-63054 and the like), dye-borate compound systems (JP-A-62-143044, JP-A-62-150242, JP-A-64-13140).
JP-A-64-13141, JP-A-64-1314
No. 2, JP-A-64-13143, JP-A-64-131
44, JP-A-64-17048, JP-A-64-72
150, JP-A-1-229003, JP-A-1-29
8348, JP-A-1-138204, JP-A2-1
79443, JP-A-2-244050, etc.) and the like.

As a component of the photosensitive layer, it is preferable to contain a linear organic polymer as a binder. As such a linear organic high molecular polymer, an addition polymer having a carboxylic acid group in the side chain, for example, JP-A-59 is used.
-44615, Japanese Patent Publication No. 54-34327, Japanese Patent Publication No. 5
8-12577, JP-B-54-25957, JP-A-54-92723, JP-A-59-53836, and JP-A-59-71048, that is, a methacrylic acid copolymer, Examples include acrylic acid copolymers, acrylic acid copolymers, itaconic acid copolymers, crotonic acid copolymers, maleic acid copolymers, and partially esterified maleic acid copolymers. Moreover, the acidic cellulose derivative which has a carboxylic acid group in a side chain is also mentioned. In addition to these, addition polymers having a cyclic acid anhydride to an addition polymer having a hydroxyl group are also useful. In particular, among these, [benzyl (meth) acrylate / (meth) acrylic acid / another addition-polymerizable vinyl monomer if necessary] copolymer and [allyl (meth) acrylate / (meth) acrylic acid / optionally And other addition-polymerizable vinyl monomers] copolymers are preferred. In addition, polyvinylpyrrolidone, polyethylene oxide, etc. are useful as the water-soluble linear organic polymer. Further, alcohol-soluble polyamide, polyether of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin, etc. are also useful for increasing the strength of the cured film.

These linear organic high molecular weight polymers can be mixed in any amount in the entire composition. But 90%
When it exceeds the range, preferable results are not obtained in terms of the strength of the formed image. It is preferably 10 to 90%, more preferably 30 to 80. The weight ratio of the photopolymerizable ethylenically unsaturated compound and the linear organic high molecular polymer is 1/9.
It is preferably in the range of ˜7 / 3. A more preferable range is 3/7 to 5/5.

In the photosensitive lithographic printing plate having a photopolymerizable layer, which is the object of the developing method of the present invention, polyvinyl alcohol is preferably used as an oxygen-shielding layer transparent to actinic rays on the photosensitive layer. The thickness of the oxygen barrier layer is suitably 0.1 μm or more and 100 μm or less. Preferably 0.5μ
m or more and 10 μm or less, more preferably 1 μm or more and 5 μm
It is the following. The oxygen-barrier layer can be stripped off prior to the development treatment or can be dissolved in the treatment liquid to be removed, but can also be dissolved and removed in the development liquid at the same time as the development treatment.

[0036]

The present invention will be described in detail with reference to the following examples.

Example 1 An aluminum plate having a thickness of 0.30 mm and a nylon brush were used.
The surface was grained with a 00 mesh pumice suspension and then thoroughly washed with water. After immersing in 10% sodium hydroxide at 70 ° C for 60 seconds for etching,
It was washed with running water, neutralized and washed with 20% nitric acid, and then washed with water. This was subjected to 160 coul / d in a 1% aqueous nitric acid solution using a sinusoidal alternating current under the condition of V _A = 12.7V.
The electrolytic surface-roughening treatment was performed with the amount of electricity at m ^{2 as} an anode. When the surface roughness was measured, it was 0.6 μ (Ra display). Then, after immersing in a 30% nitric acid aqueous solution and desmutting at 55 ° C. for 2 minutes, the thickness of the anodic oxide film was 2.7 g / in a 20% nitric acid aqueous solution at a current density of 2 A / dm ² .
Anodizing treatment was performed for 2 minutes so as to be m ² .

On the aluminum plate thus treated, a photosensitive composition having the following composition was applied in a dry coating weight of 1.4 g.
/ M ² and coated at 80 ° C. for 2 minutes to form a photosensitive layer. Pentaerythritol tetraacrylate 1.5 g Allyl methacrylate / methacrylic acid copolymer (8: 2) (copolymerization molar ratio) 2.0 g The following compound (A) 0.53 g The following compound (B) 0.12 g The following compound ( C) 0.22 g Fluorine-based nonionic surfactant 0.03 g Methyl ethyl ketone 20 g Propylene glycol monomethyl ether acetate 20 g

[0039]

[Chemical 4]

A 3% by weight aqueous solution of polyvinyl alcohol (saponification degree: 86.5-89 mol%, polymerization degree: 1000) was applied on the photosensitive layer so that the dry coating weight was 2 g / m ^2, and the temperature was 100 ° C. / Allowed to dry for 2 minutes. The photosensitive lithographic printing plate thus prepared was exposed on the image, and the developer having the composition shown in Table 1 was used as an automatic processor "PS850" manufactured by Fuji Photo Film Co., Ltd.
The first bath of "PXB" was prepared and the second bath was washed with water to 1 m ²
When 100 cc of the replenisher having the composition shown in Table 1 was replenished for development, a good image printing plate was obtained even with 1000 m ² treatment, and no precipitate was generated in the developer.

Comparative Example 1 In Example 1, when the solution having the composition shown in Table 1 was used as the developing solution and the solution having the composition shown in Table 1 was used as a replenishing solution, a treatment of 1000 m ² was performed, and a precipitate was generated in the developing solution. The developer stopped circulating due to clogging.

Example 2 Instead of coating polyvinyl alcohol on the plate coated with the photopolymerizable layer prepared in Example 1, a photosensitive printing plate was prepared by laminating a PET film (thickness: 6 μm). . When this photosensitive printing plate was exposed and developed in the same manner as in Example 1, no precipitation was generated in the developing solution even after 1000 m ² treatment.

Comparative Example 2 When the photosensitive printing plate prepared in Example 2 was exposed and developed in the same manner as in Comparative Example 1, at the time of 1000 m ² treatment, a precipitate was deposited on the bottom of the developing bath and gelled.

[0044]

[Table 1]

[0045]

According to the present invention, a photosensitive lithographic printing plate having a photopolymerizable layer is developed with an alkaline developing solution containing an alkali silicate which is repeatedly used by supplementing a developing replenisher with an automatic developing machine. However, the photopolymerizable layer and the agar-like gel do not precipitate in the developing solution for a long period of time, and a printing plate having a good image can be stably obtained.

Claims (1)

[Claims] 1. A photosensitive lithographic printing plate having a photopolymerizable layer is developed with a developer containing an alkali silicate, and the deterioration of developability due to repeated use of the developer is supplemented with a development replenisher containing an alkali silicate. A method of making a lithographic printing plate, wherein at least one of the developing solution and the developing replenisher contains an amphoteric surfactant.