JPH08110644A - Correcting agent for planographic printing plate - Google Patents

Abstract

PURPOSE: To obtain a correcting agent capable of vanishing only a desired image area without adversely affecting the required image area close to the image area to be vanished by incorporating a specified compd., an acidic substance, a water-soluble high molecular compd. and a viscosity regulating agent. CONSTITUTION: A compd. represented by formula I and/or a compd. represented by formula II, an acidic substance, a water-soluble high molecular compd. and a viscosity regulating agent are incorporated. In the formulae I, II, each of R<1> -R<5> is H, 1-12C alkyl, benzylalkyl or optionally substd. phenyl, all of R<1> -R<3> are not H and both of R<4> and R<5> are not H. An org. solvent other than the compds. represented by the formulae I, II, a surfactant and/or a colorant may further be incorporated.

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 correcting agent, and more particularly to an image portion of a lithographic printing plate produced by a photolithographic method (which repels fountain solution used during lithographic printing. The present invention relates to a correction agent used for erasing a region receiving an oil-based ink).

[0002]

2. Description of the Related Art Japanese Patent Publication No. 51-33442 (which corresponds to British Patent No. 1,408,709) has o.
A correction agent containing a lactone having 3 to 6 carbon atoms is used as a correction agent for a lithographic printing plate prepared from a photosensitive lithographic printing plate (abbreviated as PS plate) having a photosensitive layer made of a quinonediazide compound. It is disclosed. In addition, JP-A-6
In JP-A 2-27190, at least one compound selected from ethylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol monomethyl ether, lactone, N, N-dimethylformamide, N-methylpyrrolidone and cyclohexanone as component A, and component B as component B A combination composition of phosphoric acid and acetic acid, hydrogen borofluoride as component C, etc. is disclosed. However, these known correction agents have the following drawbacks. That is, in the former correction agent, as a result of the strengthening of the image area in recent years with the aim of high printing durability of the lithographic printing plate, the solubility in the correction agent is lowered, thereby significantly increasing the time required for correction, There was a problem in workability. In the latter modifier, the vapor of the solvent contained is
Since the image portion other than the desired correction portion is acted on, there is a drawback that even a necessary image portion close to the image portion to be erased is erased.

[0003]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to prevent the adverse effect on the necessary image areas in close proximity.
It is an object of the present invention to provide a lithographic printing plate correction agent capable of erasing only a desired image portion. Another object of the present invention is to provide a lithographic printing plate correction agent capable of rapidly erasing an image area.

[0004]

The present inventor has accomplished the present invention as a result of intensive studies to achieve the above object. That is, the present invention is a correcting agent for a lithographic printing plate, which comprises the following components (a) to (d). (A) Compound represented by general formula [I] and / or general formula [II] (b) Acidic substance (c) Water-soluble polymer compound (d) Viscosity modifier

[0005]

Embedded image

[0006] (respectively R ¹ to R ⁵ is wherein independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a benzyl group, a substituted or unsubstituted phenyl group. However, R ¹
-R ³ are not all hydrogen atoms, and neither R ⁴ nor R ⁵ are hydrogen atoms. )

The present invention uses the above-mentioned component (a) (compound represented by the formula [I] and / or [II]) as a solvent, or by combining with another solvent, an image of a lithographic printing plate is obtained. Excellent performance in that the time required for erasing a part is remarkably shortened, and has no adverse effect on a necessary image part (that is, not to be deleted) that is close to an unnecessary image part to be deleted. have. Furthermore, the stability over time is greatly improved. Furthermore, it is surprising that performance deterioration hardly occurs even if the filled container is opened after use, which is extremely surprising. Furthermore, since there is little odor, there is little discomfort during use,
Easy to handle.

As mentioned above, the modifying agent of the present invention comprises the compound represented by the general formula [I] and / or [II] as the component (a),
(B) Acidic substance, (c) Water-soluble polymer compound, (d) Viscosity modifier, (e) Organic solvent other than (a), (f) Surfactant, (g) Water and / or (h) a colorant and the like can be contained.

Each component contained in the correction agent composition of the present invention will be described in detail below. In formulas [I] and [II],
R ^{1 to} R ⁵ are each independently a hydrogen atom or a carbon atom number of 1 to 1.
2, preferably 1 to 4 alkyl groups (eg, methyl group, ethyl group, propyl group, isobutyl group, n-butyl group, t-butyl group), benzylalkyl groups (eg, benzyl group, p-isopropylbenzyl) Group) and a substituted or unsubstituted phenyl group (eg, phenyl group, 2-methoxyphenyl group). Moreover, these may have a substituent. However, R ^{1 to} R ³ are not all hydrogen atoms, and neither R ⁴ nor R ⁵ are hydrogen atoms. Specific examples of the compounds represented by the general formulas [I] and [II] of the component (a) include trimethyl phosphate, triethyl phosphate, tributyl phosphate, tris (2-chloroethyl) phosphate, triphenyl phosphate, tricresyl phosphate, Examples include cresyl diphenyl phosphate, di-2-ethyl phosphate, diethyl phosphite, triphenyl phosphite, tris (tridecyl) phosphite, dimethyl phosphite, ethyl azido phosphate, butoxypyrophosphate. Of these, trimethyl phosphate, dimethyl phosphite, triethyl phosphate and diethyl phosphite are particularly preferable. These above compounds can be used alone or in combination of two or more kinds. The component (a) is used in an amount of 5 to 80% by weight, preferably 10 to 60% by weight, more preferably 20 to 50% by weight, based on the correction agent of the present invention.
Within this range, erasability is preferable.

The correcting agent of the present invention can be further mixed with an organic solvent [component (e)] other than the component (a) to improve the osmotic force when the erasing liquid is applied. Further, it is economically advantageous to combine it with a general-purpose inexpensive solvent. Examples thereof include alcohols, ketones, glycol ethers, compounds having a lactone ring, and other hydrocarbon solvents. Specifically, for example, alcohols include n-hexanol, n-heptanol,
2-heptanol, n-octyl alcohol, 2-ethylexanol, 3,5,5-trimethylhexanol, nonanol, n-decanol, cyclohexanol, 2-methylcyclohexanol, benzyl alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol Etc. can be mentioned. As ketones,
Examples thereof include cyclohexanone, isophorone, methylcyclohexanone and acetophenone. As glycol ethers, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether,
Triethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether,
Ethylene glycol monopropyl ether, ethylene glycol monotertiary butyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether,

Propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monoisopropyl ether, propylene glycol monobutyl ether, propylene glycol monoisobutyl ether, propylene glycol monotertiary butyl ether , Ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether and the like. Further, polyethylene glycol and polypropylene glycol having a molecular weight of 200 to 1000 may also be mentioned monomethyl ether, monoethyl ether, monopropyl ether and isopropyl ether, monobutyl ether and the like of these compounds. As the lactone ring, γ-
Examples thereof include butyrolactone, γ-caprolactone, γ-valerolactone, γ-brerolactone and the like.
As the other hydrocarbon solvent, for example, a boiling point of 120 ° C to 3
Examples include petroleum fractions around 00 ° C, toluene, xylene, turpentine oil, kerosene, and methylnaphthalene. The solvent of the above-mentioned component (e) can be used alone or in combination of two or more kinds, and is contained in an amount of 1 to 70% by weight, preferably 3 to 50% by weight, based on the correction agent of the present invention.

The correcting agent of the present invention exerts its effect sufficiently in a range exhibiting acidity, and more preferably has a pH of 1.
-5, most preferably 1-3. The pH of the modifying agent of the present invention is adjusted by the component (b). Examples of the acidic substance of the component (b) include minerals such as phosphoric acid, metaphosphoric acid, phosphorous acid, sulfuric acid, nitric acid, hydrofluoric acid, fluorozirconic acid, hydrosilicofluoric acid, borohydrofluoric acid, and the like. Acid, citric acid, tannic acid, malic acid, glacial acetic acid, lactic acid, oxalic acid, p-
There are organic acids such as toluenesulfonic acid, phytic acid, phosphonic acid and salts thereof. Examples of the phosphonic acid include 1-hydroxyethylidene-1,1-diphosphonic acid, 1,2-diphosphono-1,2-dicarboxyethane, 1,2,2,3-tetraphosphonopropane and 2
(2′-phosphonoethyl) pyridine, aminotri (methylenephosphonic acid), vinylphosphonic acid, polyvinylphosphonic acid, 2-phosphonoethane-1-sulfonic acid, water-soluble copolymer of vinylphosphonic acid and acrylic acid and / or vinyl acetate, etc. Can be mentioned. Among these compounds, phosphoric acid, metaphosphoric acid and phytic acid are particularly excellent. The amount of component (b) used is suitably in the range of about 0.1 to 15% by weight, based on the total weight of the modifying agent of the present invention,
Most preferably, it can be contained in the range of 0.5 to 10% by weight.

The correction agent of the present invention further contains a water-soluble polymer compound [component (c)] to provide further excellent performance, that is, the ease of applying the correction agent on a lithographic printing plate using a brush. The corrective agent can be provided with properties such as prevention of blurring and bleeding. Preferred water-soluble polymer compounds include, for example, modified cellulose such as methyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose / Na salt, gum arabic, polyvinylpyrrolidone, polyvinyl methyl ether, polyethylene glycol, polypropylene glycol, vinyl methyl ether. Polymeric compounds such as maleic anhydride copolymers, vinyl acetate-maleic anhydride copolymers, PVA / maleic anhydride copolymers and the like can be mentioned. Among them, modified cellulose, polyvinylpyrrolidone, vinyl methyl ether maleic anhydride copolymer, tractane and the like are useful. The above water-soluble polymer compounds can be used alone or in combination of two or more, and the amount thereof is 0.1 to 10% by weight, most preferably 0.1% by weight based on the total weight of the correcting agent of the present invention. 5-5
Used in the range of weight percent.

The modifying agent of the present invention may optionally contain a surfactant [component (f)]. The component (f) is capable of imparting the correcting agent of the present invention, and the ability of each component contained therein to permeate better into the image area of the lithographic printing plate. Further, each component contained in the correcting agent is good. It is effective in order to form a stable solution by mixing with. Examples of the surfactant of component (f) include polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene polystyryl phenyl ether, polyoxyethylene polyoxypropylene alkyl ether, glycerin fatty acid partial ester, and sorbitan fatty acid moiety. Ester, pentaerythritol fatty acid partial ester, propylene glycol monofatty acid ester, sucrose fatty acid partial ester, oxyethylene oxypropylene block copolymer, polyoxyethylene sorbitan fatty acid partial ester, polyoxyethylene sorbitol fatty acid partial ester, polyethylene glycol fatty acid ester, polyglycerin fatty acid Partial ester, polyoxyethylenated castor oil, polyoxyethylene glycerin Nonionic surfactants such as fatty acid partial ester, fatty acid diethanolamide, N, N-bis-2-hydroxyalkylamine, polyoxyethylene alkylamine, triethanolamine fatty acid ester, trialkylamine oxide, fatty acid salt, abietin Acid salt, hydroxyalkanesulfonate, alkanesulfonate, dialkylsulfosuccinate ester salt, linear alkylbenzenesulfonate, branched chain alkylbenzenesulfonate, alkylnaphthalenesulfonate, alkylphenoxypolyoxyethylenepropylsulfonate Salt, polyoxyethylene alkylsulfophenyl ether salt, N-methyl-N-oleyl taurine sodium, methylolpropane oxyethyleneoxypropylene adduct,

N-alkylsulfosuccinic acid monoamide disodium salt, petroleum sulfonate, sulfated castor oil, sulfated beef tallow oil, sulfate ester salt of fatty acid alkyl ester, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, Fatty acid monoglyceride sulfate ester salt, polyoxyethylene alkylphenyl ether sulfate ester salt, polyoxyethylene styryl phenyl ether sulfate ester salt, alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphate ester salt, polyoxyethylene alkylphenyl ether phosphate salt Anion such as ester salt, partially saponified product of styrene-maleic anhydride copolymer, partially saponified product of olefin-maleic anhydride copolymer, and naphthalenesulfonate formalin condensate Surfactants include alkyl amine salts,
Cationic surfactants such as quaternary ammonium salts, polyoxyethylene alkylamine salts and polyethylene polyamine derivatives, amphoteric surfactants such as carboxybetaine, aminocarboxylic acid, sulfobetaine, aminosulfate, imidazoline, fluorine-based or silicone Examples include system surfactants. Among the above-mentioned surfactants, those having polyoxyethylene can be read as polyoxyalkylenes such as polyoxymethylene, polyoxypropylene and polyoxybutylene.

Of these, nonionic surfactants and anionic surfactants are preferable, and surfactants having an HLB of 9 or more are more preferable because each component contained in the correcting agent is well mixed. Furthermore, polyoxyethylene alkyl phenyl ether, oxyethylene oxypropylene block copolymer, polyoxyethylene sorbitan fatty acid partial ester, polyoxyethylene sorbitol fatty acid partial ester, polyethylene glycol fatty acid ester, polyglycerin fatty acid partial ester can be used to erase the image part of the correction agent. It is preferable because the effect is improved. Most preferred is oxyethylene oxypropylene block copolymer. These surfactants may be used alone or in combination of two or more, and preferably 0.01 to 40% by weight, more preferably 0.1 to 2% by weight based on the total weight of the modifying agent of the present invention.
It is contained in the range of 5% by weight.

The correction agent of the present invention may further contain water [component (g)]. The component (g) water promotes the dissolution of the component (c) water-soluble polymer compound and enhances the activity of the component (b) acidic substance, and further stabilizes the components by mixing them with each other. Useful for.
The amount used is preferably in the range of 0.5 to 20% by weight, most preferably 1 to 10% by weight, based on the total weight of the correction agent of the present invention. The colorant of component (h), which is used to impart the desired shade and visual contrast to the modifier of the present invention, can be selected from a wide range of dyes. As a particularly preferable dye, an indicator dyeing department having a deep dyeing such as blue, purple, and red color exhibits excellent effects.
Specific examples include dyes such as crystal violet, safranine, brilliant blue, malachite green, and acid rhodamine B, and inorganic pigments and organic pigments.

When a coloring agent is used, its amount is 0.0001 to 0.10% by weight, preferably 0.001 to 0.05% by weight, based on the total weight of the correction agent of the present invention. is there. The correction agent of the present invention preferably further contains a viscosity modifier [component (d)]. This gives the corrective agent of the present invention better writability, and for example, when the corrective agent of the present invention is applied to the image portion of the lithographic printing plate using a brush, the corrective agent may drip from the brush. It is effective in preventing such inconvenience. Such component (d)
As for the above, although the water-soluble polymer compound of the above-mentioned component (c) partially functions, fine powder of silicic acid, colloidal silica, zeolite and the like exhibit excellent performance, so that it is preferable to contain them. The amount used is preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight, still more preferably 3 to 6%, based on the total weight% of the correction agent. The viscosity of the modifier of the present invention is 100 cps to 20,
000 cps, preferably 500 cps to 15,000
It is in the cps range.

Further, a preservative, a rust preventive and the like can be added to the modifying agent of the present invention, if necessary. For example, as a preservative, phenol or its derivative, formalin, imidazole derivative, sodium dehydroacetate, 4-isothiazolin-3-one derivative, benzisothiazoline-3
-One, benztriazole derivative, amidising anidine derivative, quaternary ammonium salt, pyridine, quinoline, guanidine and other derivatives, diazine, triazole derivative, oxazole, oxazine derivative, 2-bromo-2-nitropropane-1,3-diol, Etc. The preferable addition amount is an amount that exerts a stable effect on bacteria, molds, yeasts, etc., and varies depending on the types of bacteria, molds, yeasts, but 0.01 to the correction agent at the time of use. The range of 4% by weight is preferable, and it is preferable to use two or more kinds of preservatives together so as to be effective against various molds and sterilization. In addition, a silicone antifoaming agent is preferable as the antifoaming agent. Among them, both the emulsified dispersion type and the solubilized type can be used. The optimum amount of use is in the range of 0.001 to 1.0% by weight based on the corrective agent used. Examples of the rust preventive agent include 1H benzotriazole and its derivative, benzimidazole and its derivative, and thiosalicylic acid. The preferable addition amount is 0.0001 to 0.1% by weight based on the correction agent.

The correcting agent of the present invention can be applied to positive-type and negative-type photosensitive lithographic printing plates (hereinafter referred to as PS plates), and is advantageously used for correcting and erasing image areas. Therefore, the PS plate will be described in detail below. To do. Although conventionally known diazo compounds can be used as the diazo compound used in the positive photosensitive composition, representative examples thereof include o-quinonediazides, and preferably o-naphthoquinonediazide compounds. Among o-naphthoquinone diazide compounds, particularly o-naphthoquinone diazide sulfonic acid ester or o-naphthoquinone diazide carboxylic acid ester of various hydroxy compounds, and o-of aromatic amino compounds
Naphthoquinone diazide sulfonic acid amides or o-naphthoquinone diazide carboxylic acid amides are preferred. Preferred hydroxyl compounds include condensation resins of phenols and carbonyl group-containing compounds. Examples of the phenols include phenol, cresol, resorcin, and pyrogallol, and examples of the carbonyl group-containing compound include formaldehyde, benzaldehyde, and acetone. Preferred hydroxy compounds include phenol / formaldehyde resin, cresol /
Formaldehyde resin, pyrogallol / acetone resin,
Examples thereof include resorcin / benzaldehyde resin.

Typical examples of o-quinonediazide compounds include benzoquinone- (1,2) -diazide sulfonic acid or naphthoquinone- (1,2) -diazide sulfonic acid and phenol-formaldehyde resin or cresol-formaldehyde. Ester with resin, JP-A-56-
The naphthoquinone- (1,
2) -Diazide- (2) -5-sulfonic acid ester with resorcin-benzaldehyde resin, U.S. Pat.
Ester of naphthoquinone- (1,2) -diazidosulfonic acid and pyrogallol-acetone resin described in Japanese Patent No. 635,709, and naphthoquinone- (1,1, described in JP-A-55-76346. An ester of 2) -diazide- (2) -5-sulfonic acid and resorcin-pyrogallol-acetone copolycondensate may be mentioned. Other useful o-quinonediazide compounds include those obtained by esterifying o-naphthoquinonediazidesulfonyl chloride with a polyester having a terminal hydroxyl group described in JP-A No. 50-117503.

An esterification reaction of o-naphthoquinonediazide sulfonyl chloride with a homopolymer of p-hydroxystyrene or a copolymer with other copolymerizable monomer as described in JP-A-50-113305. And a bisphenol-formaldehyde resin described in JP-A No. 54-29922 and o-
Esters with quinonediazide sulfonic acid, copolymers of alkyl acrylates, acryloyloxyalkyl carbonates and hydroxyalkyl acrylates described in US Pat. No. 3,859,099 and o
-Condensation product with quinonediazidesulfonyl chloride, reaction product of copolymer product of styrene and phenol derivative described in JP-B-49-17481 and o-quinonediazidesulfonic acid, U.S. Pat. No. 3,759,711.
As described in the specification, an amide of a copolymer of a monomer copolymerizable with p-aminostyrene and o-naphthoquinonediazide sulfonic acid or o-naphthoquinonediazidecarboxylic acid, and other polyhydroxybenzophenone And an ester compound of o-naphthoquinonediazide sulfonyl chloride.

These o-quinonediazide compounds can be used alone, but it is preferable to mix them with an alkali-soluble resin and provide this mixture as a photosensitive layer. Suitable alkali-soluble resins include novolac type phenol resins, specifically phenol formaldehyde resins, cresol formaldehyde resins, JP-A-55555.
The phenol / cresol formaldehyde copolycondensate resin as described in Japanese Patent No. 7841 is included. Further, as described in JP-A-50-125806, phenol or cresol substituted with an alkyl group having 3 to 8 carbon atoms such as t-butylphenol / formaldehyde resin together with the above-mentioned phenol resin. It is even more preferable to use a condensate with formaldehyde in combination.

Further, an alkali-soluble resin other than the above-mentioned alkali-soluble novolac type phenol resin can be blended, if necessary. For example, styrene-acrylic acid copolymer, methyl methacrylate-methacrylic acid copolymer, alkali-soluble polyurethane resin, Japanese Patent Publication No. 52-2
Examples thereof include alkali-soluble vinyl resins and alkali-soluble polybutyral resins described in Japanese Patent No. 8401. The content of the o-quinonediazide compound is preferably 5 to 80% by weight, and particularly preferably 10 to 50% by weight, based on the total solid content of the photosensitive composition. The content of the alkali-soluble resin is preferably 30 to 90% by weight, and particularly preferably 50 to 85% by weight, based on the total solid content of the photosensitive composition.

The negative type photosensitive composition contains a photosensitive diazo photosensitive material and preferably a high molecular compound, and as the photosensitive diazo photosensitive material, those conventionally known can be used. Preferred are organic solvent-soluble diazo resin salts, for example, a salt of p-diazodiphenylamine and a condensate of formaldehyde or acetaldehyde and hexafluorophosphoric acid, a salt of toluenesulfonic acid, and 2-hydroxy-4-methoxybenzophenone-. Examples thereof include salts with 5-sulfonic acid. The content of the diazo resin in the photosensitive composition according to the present invention is in the range of 1 to 50% by weight, preferably 3 to 40% by weight. Examples of the polymer compound include acrylic acid or methacrylic acid copolymer, crotonic acid copolymer,
Itaconic acid copolymer, maleic acid copolymer, cellulose derivative having carboxyl group in side chain, polyvinyl alcohol derivative having carboxyl group in side chain, hydroxyalkyl acrylate or methacrylate copolymer having carboxyl group in side chain, carboxyl An unsaturated polyester resin having a group is preferably used. More preferably, it is a polymer having an acid value of 10 to 300. Particularly, a copolymer such as hydroxyethyl methacrylate / acrylonitrile described in JP-A-50-118802 is preferably used. In addition, JP-A-2-236552
The photosensitive polymer system containing a dimethylmaleimide group described in JP-A-4-27444 can also be used.

The coated amount of the photosensitive composition provided on the support is preferably from 0.1~7g / m ^2, more preferably from 0.5-4 g / m ^2. If necessary, between the support and the photosensitive composition layer, a metal salt and hydrophilic cellulose described in JP-B-57-16349, polyvinylphosphonic acid described in JP-B-46-35685, JP-A-60-1494.
Β-alanine described in JP-A-91 or JP-A-60-23.
An undercoat layer such as polyethanolamine / hydrochloride described in 2998 may be provided. The support used in the photosensitive lithographic printing plate used in the present invention includes aluminum (including aluminum alloy), paper, plastic (for example, polyethylene, polypropylene, polyethylene terephthalate, cellulose diacetate, cellulose triacetate, propionic acid). A composite support in which aluminum is laminated or vapor-deposited on cellulose, polyvinyl acetal, polycarbonate, etc.) and a metal such as zinc or copper is preferably used.

The surface of the aluminum material enhances water retention,
It is desirable that the surface is roughened for the purpose of improving the adhesion to the photosensitive layer. Examples of the roughening method include generally known brush polishing method, ball polishing method, electrolytic etching, chemical etching, liquid honing, sand blasting and the like and combinations thereof, preferably brush polishing method, electrolytic etching, chemical method. Etching and liquid honing, of which the roughening method involving the use of electrolytic etching is particularly preferred. Further, as the electrolytic bath used in the electrolytic etching, an aqueous solution containing an acid, an alkali or a salt thereof or an aqueous solution containing an organic solvent is used, and among these, an electrolytic solution containing hydrochloric acid, nitric acid or a salt thereof is particularly used. Liquids are preferred. Further, the surface-roughened aluminum plate is desmutted with an acid or alkali aqueous solution, if necessary. The aluminum plate thus obtained is preferably anodized,
Particularly preferred is a method of treating with a bath containing sulfuric acid or phosphoric acid. Further, if necessary, surface treatment such as sealing treatment and immersion in an aqueous solution of potassium fluorozirconate can be performed.

The PS plate thus obtained was passed through a transparent original map to obtain a carbon arc lamp, a mercury lamp, a metal halide lamp,
It is exposed by a light source rich in actinic rays, such as a tungsten lamp, and then developed in a development processing step by wet processing. The developer used in the above-mentioned development treatment step is an alkaline solution containing water as a main solvent, and may contain an organic solvent, an anionic surfactant, an inorganic salt, etc., if necessary. It is also useful to further contain a defoaming agent, a wetting agent, etc. in the developing solution if necessary.
As a method for developing the PS plate imagewise exposed with the above-mentioned developing solution, various conventionally known methods can be used. Specifically, a method of immersing the image-exposed PS plate in a developer, a method of spraying the developer from a large number of nozzles onto the photosensitive layer of the PS plate, and a sponge wet with the developer Examples thereof include a method of wiping the photosensitive layer and a method of roller-coating a developing solution on the surface of the photosensitive layer of the PS plate. Further, after the developing solution is applied to the photosensitive layer of the PS plate in this way, the surface of the photosensitive layer can be lightly rubbed with a brush or the like.

After the development processing as described above, a combination of washing, rinsing, desensitizing treatment and the like is performed to complete the development processing of the PS plate. As described above, when the lithographic printing plate obtained by subjecting the PS plate to image exposure and development has an unnecessary image portion, the image agent is erased by applying the correction agent of the present invention on the image portion. . When the correction agent of the present invention is applied to the image area of a lithographic printing plate, it is preferable to wash the lithographic printing plate after development sufficiently before applying it immediately after development.
Although the erasing speed is slightly slower, a gumming lithographic printing plate can be provided with a correcting agent. As a specific method of applying the correction agent of the present invention to the image area of the planographic printing plate, a method of incorporating the correction agent of the present invention into a brush and applying the correction agent to a desired image area to be erased is generally used. The applied corrective agent is left as it is for about 10 seconds to about 1 minute, and then washed with water to remove the corrective agent, so that the image portion of the portion to which the corrective agent is applied is removed cleanly and becomes a non-image area. After that, it is processed by a usual method (for example, gumming) and used as a lithographic printing plate.

[0030]

The present invention will be described in more detail with reference to the following examples. Unless stated otherwise, "parts" are parts by weight,
“%” Shall mean “% by weight”. Example 1 An aluminum plate having a thickness of 0.3 mm was electrochemically roughened in a nitric acid solution, thoroughly washed, and then anodized in a sulfuric acid solution to form an oxide film of 2.5 g / m ^{2 on} the aluminum plate. Formed on the surface. After washing with water and drying, JP-A-56-104
No. 4, gazette of resorcin benzaldehyde resin and naphthoquinone 1,2-diazide-5-sulfonyl chloride, 3 parts of ester compound, cresol formalin novolac resin, 9 parts, and Victoria Pure Pro BOH (Hodogaya Chemical Co., Ltd.) Made by company) 0.
1. A photosensitive solution prepared by dissolving 12 parts in 100 parts of 2-methoxyethanol was coated on the above support with a rotary coating machine and dried.
A positive PS plate having a photosensitive layer of 8 g / m ² was obtained. A halftone dot transparent positive image was adhered on this, exposed for 60 seconds with a metal halide lamp from a distance of 0.8 m, and developed with the following developing solution to obtain a printing plate. (Developer) Potassium silicate A (SiO ₂ 26%, K ₂ O 13.5%) 120 parts 86% Potassium hydroxide 15.5 parts Water 500 parts The lithographic printing plate thus obtained has the edge of the positive film on the plate surface. It remained thin as an image. On the other hand, the correction agent of the present invention was prepared as follows. First, hydroxypropyl methyl cellulose (trade name Metroze 60SH50 (Shin-Etsu Chemical Co., Ltd.) was added to a liquid obtained by mixing 37.5 parts of triethyl phosphate, 30 parts of γ-butyrolactone, and 10 parts of pure water.
Manufactured)) 1.5 parts was dissolved. Next, oxyethylene oxypropylene block polymer (average molecular weight of 2,000
Polymerized with ethylene oxide on both ends of polypropylene glycol. 15 parts (molecular weight: 10,000, ethylene oxide content: 80%) were dispersed. Phosphoric acid (85%) 2 parts and crystal violet 0.00
3 parts was added and sufficiently stirred to form a uniform solution. To this, 4.0 parts of powdered silicon dioxide was added and dispersed to obtain a viscous corrective agent. The pH of this modifier is 1.4 at 25 ° C.
It was 6. The prepared corrector was included in a brush and applied to the area where the edge of the film on the lithographic printing plate remained as an image, and after 30 seconds, water was sprayed to wash off. The image area formed by the film cutout was completely exposed to the hydrophilic layer and could not be distinguished from other non-image areas.

The thus-corrected version is Gu-
7 (manufactured by Fuji Photo Film Co., Ltd.) is Gu-7: water = 1:
After diluting to 1 and gumming, it was mounted on an offset printing machine Heidel SORM type and printed on 10,000 sheets, but no stain was observed in the erased image portion, and a beautiful printed matter was obtained. The correction agent of the present invention has a minimal liquid bleeding even when erasing small details, so that the correction work can be carried out with peace of mind, and it is highly safe from a physiological point of view and there is almost no inconvenience and it is excellent in suitability for use. Was there.

Further, as shown in Table 1 below, Examples 2 to 5 were prepared in the same manner as in Example 1 to obtain the correcting agent of the present invention. Furthermore, Comparative Examples 1 and 2 were prepared in the same manner as in Example 1 except that as shown in Table 1, to obtain comparative corrective agents. Using this, erasing was performed in the same manner as in Example 1, but in Examples 1 to 5, the erasability was good and there was no bleeding,
The results were all good. Further, as a forced aging test, the correcting agent was stored for 7 days at 50 ° C./80% RH and then examined for deterioration of erasability. Examples 1 to 5 were all good, like the new solution. . Further, the correction fluid of the present invention has no odor and is convenient to handle. The results are summarized in Table 2.

[0033]

[Table 1]

[0034]

[Table 2] Table 2 Example ratio Comparison Example 1 2 3 4 5 12 Eradication property A A A A A C C Ease of bleeding A A A A A A A B Stable at 50 ° C / 80% RH Sex (7 days) A A A A A C C Odor A A A B A B A B

Erasability: In the erasing work in which a correction agent is applied to the image area and left for a certain period of time, and then the correction agent is washed off with water, the above-mentioned leaving time is changed in 5 second increments by 5 seconds. Then, the number of seconds required to complete the erasing of the image area was measured and evaluated according to the following criteria. A: Within 5 seconds. B: 10 seconds longer than 5 seconds. C: 20 seconds or longer than 10 seconds. D: Longer than 20 seconds. Ease of bleeding: 30% A correction agent is applied at a distance of 1 mm, 2 mm, or 3 mm from the boundary of the halftone dot image area, left for 10 minutes, and then rinsed off to examine the halftone dot image for corrosion. A: There is no effect even when applied with a space of 1 mm. B: There is no effect at an interval of 2 mm, but there is no effect at an interval of 2 mm. C: There is an effect even if there is an interval of 3 mm. Stability with time: 50 ° C./80% RH of the correction agent. It is left for 7 days, and then evaluated with the same evaluation as "erasability". Odor: A: None B: Somewhat C: Yes

[0036]

INDUSTRIAL APPLICABILITY The correction agent of the present invention has an extremely high erasing speed in the image area. Therefore, the erasing process is shortened, and the efficiency of plate making work is improved. The correction agent of the present invention has an advantage that a desired image area can be erased without adversely affecting an adjacent image area. Therefore, it is possible to easily and completely erase complicated image portions. Further, the correction agent of the present invention has excellent stability over time.

Claims (1)

[Claims] 1. A correcting agent for a lithographic printing plate, which comprises the following components (a) to (d): (A) Compound represented by general formula [I] and / or general formula [II] (b) Acidic substance (c) Water-soluble polymer compound (d) Viscosity modifier (In the formula, R ^{1 to} R ⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a benzylalkyl group, or a substituted or unsubstituted phenyl group, provided that R ^{1 to} R ³ are all hydrogen atoms. None, and neither R ⁴ nor R ⁵ is a hydrogen atom.)