JP2000321792A - Correcting agent for planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to rapidly erase only the desired image part, to make a correcting agent easily removable by water washing and to eliminate the adverse influence to be exerted on the adjacent image parts by incorporating a specific compound into the agent. SOLUTION: The correcting agent contains one kind of the compound expressed by formula I, II or III. In the formula I, R1 denotes a hydrogen atom or methyl group; R2 denotes a hydrogen atom or 1-4C alkyl group and (m) and (n) are values to attain a molecular weight 3000 to 50000. In the formula II, R3 and R6 respectively independently denotes hydrogen atoms or 1-9C alkyl groups, provided that all R3 and R6 of the polymer chain do not denote hydrogen atoms and (o) is a value to attain molecular weight 5,000 to 50,000. In the formula III, R7 denotes a hydrogen atom or methyl group; R8 denotes hydrogen atom or 1-4C alkyl group, alkaline metal or NH4 and (p) and (q) are values to attain a molecular weight 80,000 to 250,000.

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 modifier, and more particularly to an image portion of a lithographic printing plate manufactured by photolithography (which repels fountain solution used during lithographic printing). Correction area used to erase the oil-based ink).

[0002]

2. Description of the Related Art JP-B-51-33442 (corresponding to British Patent No. 1,408,709) discloses a photosensitive lithographic printing plate (PS plate) having a photosensitive layer comprising an o-quinonediazide compound. As a modifier for a lithographic printing plate produced from a plate, a modifier containing a lactone having 3 to 6 carbon atoms is disclosed. JP-A-62-271
No. 90 discloses ethylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol monomethyl ether, lactone as component A.
A combination composition comprising at least one compound selected from N, N-dimethylformamide, N-methylpyrrolidone and cyclohexanone, phosphoric acid and acetic acid as component B, and hydrogen borofluoride as component C is disclosed. However, these known modifiers have the following disadvantages. That is, in the former correction agent, the image portion has been strengthened in recent years in accordance with the high printing durability direction of the lithographic printing plate, as a result, the solubility in the correction agent has decreased, thereby significantly increasing the time required for correction, There was a problem with workability. In the latter correction agent, the vapor of the contained solvent acts on the image part other than the desired correction part, so that the necessary image part close to the image part to be deleted is also deleted. there were. On the other hand, the correcting agent is usually washed and removed after being applied to a portion to be erased, but if the removing agent is not quickly removed in the washing process, there is a high possibility that the removed correcting agent comes into contact with the image portion adjacent to the erased portion, As a result, there is also a problem that a good plate cannot be obtained.

[0003]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an image processing apparatus which does not adversely affect a necessary image portion in the vicinity.
An object of the present invention is to provide a lithographic printing plate modifying agent which can quickly erase only a desired image portion and is easily removed by water when the modifying agent is washed away with water and does not adversely affect an adjacent image portion.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object, and as a result, by adding a specific water-soluble polymer compound to the modifying agent, a good modifying agent was obtained. And found that the present invention was achieved. The present invention provides a lithographic printing plate modifier comprising at least one compound represented by the following general formula [I], [II] or [III].

[0005]

Embedded image

(In the formula [I], R ¹ represents a hydrogen atom or a methyl group, R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and m and n have a molecular weight of 3,000 to 500.
This value is 00. In the formula [II], R ³ , R ⁴ , R ⁵ , R ⁶
Each independently represents a hydrogen atom or an alkyl group having 1 to 9 carbon atoms, provided that all R ³ ,
R ⁴ , R ⁵ and R ⁶ do not represent a hydrogen atom, and o is a value that gives a molecular weight of 5,000 to 50,000. Formula [III]
Wherein R ⁷ represents a hydrogen atom or a methyl group, R ⁸ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkali metal or NH ₄ , and p and q have a molecular weight of 80,000 to 2
This is a value that is 50,000. )

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The correcting agent of the present invention containing the above-mentioned components is particularly easy to flow with water when it is applied to an erased portion of an image area of a lithographic printing plate and then washed and removed.
That is, since the cleaning agent is easily removed by washing with water, an excellent performance is exerted in that the removal correcting agent does not come into contact with the image portion adjacent to the erased portion and does not affect the plate. As described above, the modifying agent of the present invention contains (a) at least one compound represented by the general formula [I], [II] or [III], and further comprises (b) another water-soluble compound. Polymer compound, (c) organic solvent, (d) acidic substance, (e) surfactant, (f) water,
(G) a colorant, (h) a viscosity modifier, (i) a preservative, and the like. Hereinafter, each component contained in the modifier composition of the present invention will be described in detail.

Component (a) is a compound represented by the general formula [I], [II] or [II]
At least one compound represented by I] is a water-soluble polymer compound derived from vinylpyrrolidone. The compound represented by the general formula [I] is a linear random copolymer. In the formula, when R ² is an alkyl group having 1 to 4 carbon atoms, the alkyl group may be linear or branched, but is preferably linear. In the formula, m and n show values such that the molecular weight is 3,000 to 50,000, and more preferably 5,000 to 30,000. m and n also mean that the content of vinylpyrrolidone is generally 40-90 mol%, preferably 50-80 mol%, more preferably 6 mol%.
The value is such that it becomes 0 to 80 mol%. General formula [I]
Specific examples of the compound represented by are a vinylpyrrolidone / vinyl acetate copolymer in which R ¹ represents a hydrogen atom and R ² represents a methyl group. The compound represented by the general formula [I] is commercially available as an alcohol solution, an aqueous solution, or a powder, and a commercially available product can be used in the present invention. Such commercial products include PVP
/ VA copolymer (made by ISP) is available in each grade.

The compound represented by the general formula [II] is a water-soluble polymer compound in which an α-olefin is grafted on polyvinylpyrrolidone. In the formula, the alkyl groups represented by R ³ , R ⁴ , R ⁵ , and R ⁶ may be linear or branched, but are more preferably linear. The alkyl group has 1 to 9 carbon atoms, preferably 1 to 4 carbon atoms, and particularly preferably an n-butyl group. In the formula, o indicates a value such that the molecular weight is 5,000 to 50,000, and more preferably 7000 to 30,000. The grafting position is at least one of R ³ , R ⁴ , R ⁵ , and R ⁶ . Further, in particular, a polymer mainly composed of an alkyl group grafted to R ⁵ can also be mentioned. About 80 to 95% by weight of polyvinylpyrrolidone and about 5 to 20% by weight of a 1-alkene, such as 1-alkene
Such polymers include those substituted with butene. Such a compound represented by the general formula [II] is commercially available as an alcohol solution, an aqueous solution, or a powder,
In the present invention, commercially available products can be used. As a commercially available product, Ganex (registered trademark) P-904 (manufactured by ISP)
Each grade product is known.

The compound represented by the general formula [III] is a linear random copolymer. In the formula, when R ⁸ represents an alkyl group having 1 to 4 carbon atoms, the alkyl group may be linear or branched, but is preferably linear. In the formula, p and q are such that the content of vinylpyrrolidone is 40 to 95.
A suitable value is such that it is in the range of mol%, preferably 50 to 90 mol%. Specific examples of the compound represented by the general formula [III] include a vinylpyrrolidone / acrylic acid copolymer in which R ⁷ and R ⁸ both represent a hydrogen atom. Such a compound is commercially available, for example, acrylidone (registered trademark, manufactured by ISP), and such a commercially available product can be used in the present invention. General formulas [I], [I
At least one compound represented by I] or [III] is
They can be used alone or in combination of two or more. The amount used is suitably in the range from 0.1 to 10% by weight, more preferably in the range from 0.3 to 5% by weight, based on the total weight of the modifying agent of the present invention.

The modifying agent of the present invention further contains another water-soluble polymer compound (component (b)), so that the modifying agent is applied to a lithographic printing plate using a brush with better performance. The modifying agent can be provided with properties such as ease of spreading in the case (no fading) and prevention of bleeding. Preferred water-soluble polymer compounds include, for example, methyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose N
a. Modified cellulose such as a salt, gum arabic, structan, polyvinyl methyl ether, polyethylene glycol, polypropylene glycol, vinyl methyl ether-maleic anhydride copolymer, and high molecular compounds such as vinyl acetate-maleic anhydride copolymer. Can be Among them, modified cellulose, polyvinylpyrrolidone, vinyl methyl ether maleic anhydride copolymer, structan and the like are useful. The above-mentioned water-soluble polymer compounds can be used alone or in combination of two or more, and the amount thereof is 0.05 to 10% by weight, most preferably 0.5 to 10% by weight, based on the total weight of the modifying agent of the present invention. It is used in the range of 1 to 5% by weight.

The organic solvent (component (c)) used in the modifier of the present invention includes alcohol, ketone or glycol ether. Specific examples of the alcohol include n-hexanol, 2-ethylbutanol, n-heptanol, n-octanol, 2-ethylhexanol, nonanol, cyclohexanol, 2-methylcyclohexanol, benzyl alcohol, and tetrahydrofurfuryl alcohol. Examples of the ketone include methyl amyl ketone, methyl-n-hexyl ketone, di-n-propyl ketone, diacetone alcohol,
Acetonylacetone, isophorone, phorone, cyclohexanone, methylcyclohexanone, and acetophenone are listed. As the glycol ether, the following general formula [I
V] or the compound represented by [V]. [IV] _{^{R 9 O- (CH 2 CH (}} R 10) -O) m-R 11 [V] ^{_{R 12 O- (CH 2 CH 2}} -O) p -CO-CH 3 in formula R ⁹ to R ¹² Independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a benzyl group, a phenyl group, or a cyclic alkyl group, and m and p each represent an integer of 1 to 20.

Specific examples thereof include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether,
Diethylene glycol dimethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, diethylene glycol diethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol Monobutyl ether, diethylene glycol dibutyl ether,
Ethylene glycol monobutyl ether acetate, ethylene glycol monobenzyl ether, diethylene glycol monobenzyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, propylene glycol monoethyl ether, dipropylene glycol monoethyl Ether, tripropylene glycol monoethyl ether, dipropylene glycol diethyl ether and the like.

Examples of the organic solvent (c) include, in addition to the above, monomethyl ether, monoethyl ether, monopropyl ether, isopropyl ether, monobutyl ether, etc. of polyethylene glycol and polypropylene glycol having a molecular weight of 200 to 1,000 and their compounds. be able to. In addition, γ-butyrolactone,
γ-valerolactone, γ-caprolactone, γ-laurolactone, δ-valerolactone, hexanolactone,
N, N-dimethylformamide, acetamide, dimethyl sulfoxide, toluene, xylene, petroleum fractions having a boiling point of around 120 ° C. to 300 ° C., and methylnaphthalene as hydrocarbon solvents. The above-mentioned solvents of component (c) can be used alone or in combination of two or more, and are contained in the modifier in the present invention in an amount of 1 to 80% by weight, preferably 3 to 70% by weight.

The modifying agent of the present invention exerts its effect sufficiently within the acidic range, and more preferably has a pH of 1
-5, most preferably 1-3. preferable
Examples of the acidic substance of the component (d) required for adjusting the pH range include phosphoric acid, metaphosphoric acid, phosphorous acid, sulfuric acid, nitric acid, hydrofluoric acid, fluorinated zirconic acid, and hydrogensilicon fluoride. Mineral acids such as acid, borohydrofluoric acid, etc., citric acid, tannic acid,
There are organic acids such as malic acid, glacial acetic acid, lactic acid, oxalic acid, p-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, 2 (2'-phosphonoethyl)
Examples thereof include pyridine, aminotri (methylenephosphonic acid), vinylphosphonic acid, polyvinylphosphonic acid, 2-phosphonoethane-1-sulfonic acid, and a water-soluble copolymer of vinylphosphonic acid and acrylic acid and / or vinyl acetate. Among these compounds, phosphoric acid, metaphosphoric acid and phytic acid are particularly excellent, with a range of about 0.1 to 15% by weight, most preferably 0. It can be contained in the range of 0.5 to 10% by weight.

The modifying agent of the present invention can contain a surfactant (component (e)) if necessary. Component (e) can impart the modifier of the present invention and the components contained therein to the ability to better penetrate into the image area of the lithographic printing plate. To form a stable solution. Examples of the surfactant of the component (e) include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl 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, trimethylolpropane, glycerin, etc. to which oxyethylene and oxypropylene are added,

Polyoxyethylene sorbitan fatty acid partial ester, polyoxyethylene sorbitol fatty acid partial ester, polyethylene glycol fatty acid ester, polyglycerin fatty acid partial ester, polyoxyethylated castor oil, polyoxyethylene glycerin fatty acid partial ester, fatty acid diethanolamide, N, N-bis-
2-hydroxyalkylamine, polyoxyethylene alkylamine, triethanolamine fatty acid ester,
Nonionic surfactants such as trialkylamine oxides, fatty acid salts, abietic acid salts, hydroxyalkanesulfonates, alkanesulfonates, dialkylsulfosuccinates, straight-chain alkylbenzenesulfonates, branched-chain alkylbenzenesulfones Acid salt, alkyl naphthalene sulfonate, alkylphenoxy polyoxyethylene propyl sulfonate, polyoxyethylene alkyl sulfophenyl ether salt, N-methyl-N-oleyltaurine sodium,

N-alkyl sulfosuccinic acid monoamide disodium salt, petroleum sulfonate, sulfated castor oil, sulfated tallow oil, sulfate of fatty acid alkyl ester, alkyl sulfate, polyoxyethylene alkyl ether sulfate, Fatty acid monoglyceride sulfate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene styryl phenyl ether sulfate, alkyl phosphate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl phenyl ether phosphate Anions such as ester salts, partially saponified styrene-maleic anhydride copolymers, partially saponified olefin-maleic anhydride copolymers, and naphthalene sulfonate formalin condensates 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, and imidazoline; fluorine-based or silicone Surfactants. Among the surfactants mentioned above, the term "polyoxyethylene" can be read as a polyoxyalkylene such as polyoxymethylene, polyoxypropylene, or polyoxybutylene.

Of these, nonionic surfactants and anionic surfactants are preferred, and surfactants having an HLB of 9 or more are more preferred because the components contained in the modifier are mixed well. 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, and polyglycerin fatty acid partial ester are used to erase the image area of the modifying agent. It is preferable to improve the effect. Most preferred are oxyethylene oxypropylene block copolymers. These surfactants may be used alone or as a mixture of two or more kinds, and preferably in the range of 0.01 to 40% by weight, more preferably in the range of 0.1 to 25% by weight based on the total weight of the modifying agent of the present invention. To be included.

The modifying agent of the present invention can further contain water (component (f)). The water of the component (f) promotes the dissolution of the water-soluble polymer compound of the components (a) and (b) and enhances the activity of the acidic substance of the component (d). It is useful to stabilize. The amount used is preferably from about 0.5 to about 20% by weight, most preferably from 1 to 10% by weight, based on the total weight of the modifying agent according to the invention.
% By weight. The colorant of component (g) is used to impart a desired color to the modifier of the present invention to give visual contrast, and can be selected from a wide range of dyes. Particularly preferred dyes are blue, purple,
An indicator dye having a deep dyeing such as red exhibits an excellent effect. Specifically, for example, crystal violet,
Dyes such as safranin, brilliant blue, malachite green, and acid rhodamine B, as well as inorganic pigments and organic pigments. When a coloring agent is used, its amount is about 0.0001 to about the total weight of the modifying agent of the present invention.
It is about 0.10% by weight, preferably in the range of 0.001 to 0.05% by weight.

It is preferable that the modifier of the present invention further contains a viscosity modifier (component (h)). this is,
The correction agent of the present invention is provided with better writability, for example, when the correction agent of the present invention is applied to an image portion of a lithographic printing plate using a brush, there is a disadvantage that the correction agent drips from the brush. This is effective in preventing the occurrence. Such component (h)
As the water-soluble polymer compounds of the above-mentioned components (a) and (b), a part thereof functions, but fine silica powder, colloidal silica, zeolite, etc. exhibit excellent performance, so that they should be contained. Is preferred. The amount used is preferably from 1 to 10% by weight, more preferably from 3 to 6% by weight, based on the total weight of the modifying agent.

Further, a preservative, a rust preventive, and the like can be added to the modifier of the present invention as needed. For example, as a preservative, phenol or a derivative thereof, formalin, imidazole derivative, sodium dehydroacetate, 4-isothiazolin-3-one derivative, benzoisothiazoline-3
-One, a benztriazole derivative, an amidizing anidine derivative, a quaternary ammonium salt, a derivative such as pyridine, quinoline, and guanidine, a diazine, a triazole derivative, an oxazole, an oxazine derivative, 2-bromo-2-nitropropane-1,3-diol, And the like. The preferred amount of addition is an amount that exerts a stable effect on bacteria, mold, yeast, and the like, and varies depending on the type of bacteria, mold, and yeast.
The range of 0.01 to 4% by weight is preferable, and various molds,
It is preferable to use two or more preservatives in combination so as to have an effect on sterilization. In addition, a silicone antifoaming agent is preferable as the antifoaming agent. Among them, an emulsified dispersion type and a solubilized type can be used. The amount used is based on the modifier used
The range of 0.001 to 1.0% by weight is optimal. As rust inhibitors, for example, 1H benzotriazole and its derivatives,
Benzimidazole and its derivatives, thiosalicylic acid and the like can be mentioned. A preferable addition amount is 0.0001 to 0.1% by weight based on the modifying agent.

The modifying agent of the present invention can be applied to positive-working and negative-working photosensitive lithographic printing plates (hereinafter referred to as PS plates), and is advantageously used when correcting and erasing an image area. explain. As the diazo compound used in the positive photosensitive composition, conventionally known diazo compounds can be used, and typical examples thereof include o-quinonediazides, and preferably o-naphthoquinonediazide compounds. Among the o-naphthoquinonediazide compounds, o-naphthoquinonediazidesulfonic acid esters or o-naphthoquinonediazidecarboxylic acid esters of various hydroxy compounds, and o-naphthoquinonediazidecarboxylic acid esters of aromatic amino compounds are particularly preferred.
Naphthoquinonediazidosulfonic acid amide or o-naphthoquinonediazidocarboxylic acid amide is preferred. Preferred hydroxyl compounds include condensation resins of phenols and carbonyl group-containing compounds. Examples of the phenols include phenol, cresol, resorcinol 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,
Resorcin-benzaldehyde resin.

Representative examples of the o-quinonediazide compound include benzoquinone- (1,2) -diazidesulfonic acid or naphthoquinone- (1,2) -diazidesulfonic acid and phenol-formaldehyde resin or cresol-formaldehyde. Ester with resin, JP-A-56-
No. 1044, naphthoquinone- (1,
2) -Diazide- (2) -5-sulfonic acid ester with resorcin-benzaldehyde resin, U.S. Pat.
Naphthoquinone described in 35,709
Ester of (1,2) -diazidesulfonic acid with pyrogallol-acetone resin, naphthoquinone- (1,2) -diazide- (2) -5-sulfonic acid described in JP-A-55-76346. And resorcin-pyrogallol-acetone copolycondensate. Other useful o-quinonediazide compounds are disclosed in
A polyester obtained by subjecting a polyester having a terminal hydroxyl group described in JP-A No. 0-117503 to an esterification reaction with o-naphthoquinonediazidosulfonyl chloride;

O-naphthoquinonediazidosulfonyl chloride is esterified with a homopolymer of p-hydroxystyrene or a copolymer with another copolymerizable monomer as described in JP-A-50-113305. And a bisphenol-formaldehyde resin described in JP-A-54-29922 and o-
Esters with quinonediazidesulfonic acid, U.S. Pat.
No. 859,099, a condensation product of a copolymer of alkyl acrylate, acryloyloxyalkyl carbonate and hydroxyalkyl acrylate with o-quinonediazidosulfonyl chloride.
No. 9-17481, a reaction product of a copolymer product of styrene and a phenol derivative with o-quinonediazide sulfonic acid, p-type as described in U.S. Pat. No. 3,759,711. Copolymers of monomers copolymerizable with aminostyrene and o-naphthoquinonediazidosulfonic acid or amides of o-naphthoquinonediazidocarboxylic acid, and other ester compounds of polyhydroxybenzophenone and o-naphthoquinonediazidosulfonyl chloride. No.

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 novolak-type phenol resins, specifically, phenol formaldehyde resin, cresol formaldehyde resin,
Phenol as described in US Pat.
Cresol formaldehyde copolycondensate resin and the like are included. Further, as described in JP-A-50-125806, t-
When a phenol or cresol substituted with an alkyl group having 3 to 8 carbon atoms such as butylphenol-formaldehyde resin is used in combination with a condensate of formaldehyde,
Even more preferred.

Further, an alkali-soluble resin other than the above-mentioned alkali-soluble novolak type phenol resin can be blended as required. For example, styrene-acrylic acid copolymer, methyl methacrylate-methacrylic acid copolymer, alkali-soluble polyurethane resin, and JP-B-52-2
No. 8401, such as alkali-soluble vinyl resins and alkali-soluble polybutyral resins. The content of the o-quinonediazide compound is preferably from 5 to 80% by weight, particularly preferably from 10 to 50% by weight, based on the total solid content of the photosensitive composition. The content of the alkali-soluble resin is preferably from 30 to 90% by weight, particularly preferably from 50 to 85% by weight, based on the total solid content of the photosensitive composition.

The negative photosensitive composition contains a photosensitive diazo resin and preferably a high molecular compound, and conventionally known photosensitive diazo resins can be used. Preferred are salts of diazo resins soluble in organic solvents, such as salts of condensates of p-diazodiphenylamine and formaldehyde or acetaldehyde with hexafluorophosphoric acid, salts of toluenesulfonic acid, 2-hydroxy-4-
And salts with methoxybenzophenone-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, a cellulose derivative having a carboxyl group in a side chain, and a carboxyl group in a side chain. Polyvinyl alcohol derivatives, hydroxyalkyl acrylates or methacrylate copolymers having a carboxyl group in the side chain, unsaturated polyester resins having a carboxyl group, and the like are preferably used. More preferably, the polymer has an acid value of 10 to 300. In particular, JP 50
A copolymer such as hydroxyethyl methacrylate / acrylonitrile described in JP-A-118802 is preferably used. Further, photosensitive polymer systems containing a dimethylmaleimide group described in JP-A-2-236552 and JP-A-4-274429 can also be used.

Further, for example, EP 0874282A1, JP-A-10-293401, and JP-A-10-39509 further contain an acid generator, a crosslinking agent capable of crosslinking by an acid, a polymer compound having an alkali-soluble group, and an infrared absorber.
JP, JP-A-9-58143, WO 97/39894
And EP 0823327 A2, etc. can also be used for a photosensitive plate system containing a compound.

The coating amount of the photosensitive composition provided on the support is preferably 0.1 to 7 g / m ^2, more preferably
0.5 to 4 g / m ² . If necessary, a metal salt and hydrophilic cellulose described in JP-B-57-16349, a polyvinylphosphonic acid described in JP-B-46-35885, and a JP-A-60-1494 may be added between the support and the photosensitive composition layer.
No. 91, JP-A-60-23
An undercoat layer such as polyethanolamine / hydrochloride described in Japanese Patent No. 2998 may be provided. Examples of the support used in the photosensitive lithographic printing plate used in the present invention include aluminum (including an aluminum alloy), paper, and plastic (eg, polyethylene, polypropylene, polyethylene terephthalate, cellulose diacetate, cellulose triacetate, propionic acid). A composite support in which aluminum is laminated or vapor-deposited on a metal such as cellulose, polyvinyl acetal, polycarbonate, and zinc and copper is preferably used.

The surface of the aluminum material enhances water retention,
It is desirable that the surface has been roughened for the purpose of improving the adhesion to the photosensitive layer. Examples of the surface roughening method include generally known methods such as a brush polishing method, a ball polishing method, electrolytic etching, chemical etching, liquid honing, sand blasting and the like, and combinations thereof. Preferably, a brush polishing method, electrolytic etching, chemical etching, or the like is used. Surface etching and liquid honing, of which a surface roughening method including the use of electrolytic etching is particularly preferable. 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. Among these, an electrolytic solution containing hydrochloric acid, nitric acid or a salt thereof is particularly used. Liquids are preferred. Further, the aluminum plate subjected to the surface roughening treatment is desmutted with an acid or alkali aqueous solution as required. The aluminum plate thus obtained is desirably anodized,
Particularly preferred is a method of treating with a bath containing sulfuric acid or phosphoric acid. Further, if necessary, a surface treatment such as sealing treatment or other immersion in an aqueous solution of potassium fluorozirconate can be performed. The average surface roughness of the support is 0.
It is preferably about 1 to 1.0 μm.

The PS plate thus obtained is passed through a transparent original drawing through 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 developing process by wet processing. The developing solution used in the developing step is an alkaline solution containing water as a main solvent, and a solution containing an organic solvent, an anionic surfactant, an inorganic salt or the like as necessary for the alkali agent is used. It is also useful to further include an antifoaming agent, a wetting agent, and the like in the developer as needed.
As a method for developing the PS plate that has been image-exposed with the above-described developer, various conventionally known methods can be used. Specifically, a method of immersing an image-exposed PS plate in a developing solution, a method of spraying a developing solution from a number of nozzles onto a photosensitive layer of the PS plate, and a method of spraying a PS plate with a sponge wetted with a developing solution. Examples of the method include a method of wiping the photosensitive layer and a method of applying a developing solution to the surface of the photosensitive layer of the PS plate with a roller. After the developer is applied to the photosensitive layer of the PS plate in this manner, the surface of the photosensitive layer can be lightly rubbed with a brush or the like.

After the above-described development processing, processing combining water washing, rinsing, and desensitizing processing 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 correcting agent of the present invention is applied on the image portion to erase the image portion. . When the correcting agent of the present invention is applied to the image area of a lithographic printing plate, it is preferable to apply the modified lithographic printing plate after sufficiently washing it with water, rather than immediately after the development.
Further, although the erasing speed is slightly reduced, a correcting agent can be applied to the gummed lithographic printing plate. As a specific method of applying the correcting agent of the present invention to the image area of a lithographic printing plate, a method of including the correcting agent of the present invention in a brush and applying the same to a desired image area to be erased is general. The applied correction agent is allowed to stand for about 10 seconds to about 1 minute, and then washed with water to remove the correction agent, so that the image portion of the portion to which the correction agent is applied is cleanly removed and becomes a non-image portion. Thereafter, it is processed by a usual method (for example, gumming) and used as a lithographic printing plate.

[0035]

According to the present invention, the corrective agent of the present invention can quickly erase only a desired image portion without adversely affecting an adjacent necessary image portion, and can be easily removed by water at the time of washing with water. In addition, the present invention exerts an excellent performance of not affecting the plate without the disadvantage that the removal correcting agent comes into contact with the image portion adjacent to the erased portion.

[0036]

The present invention will be described in more detail with reference to the following examples. Unless otherwise specified, "parts" refers to parts by weight,
“%” Means “% by weight”. Example 1 An aluminum plate having a thickness of 0.3 mm was polished with a brush, and then roughened electrochemically in a nitric acid solution, washed well, and then anodized in a sulfuric acid solution to give 2.5 g / m ² . An oxide film was formed on the surface of the aluminum plate. After washing with water and drying, 3 parts of esterified product of resorcinbenzaldehyde resin, naphthoquinone 1,2-diazido-5-sulfonyl chloride and cresol formalin novolak resin 9 synthesized according to the examples of JP-A-56-1044.
And 0.12 parts of Victoria Pure Blue BOH (manufactured by Hodogaya Chemical Industry Co., Ltd.) in 100 parts of 2-methoxyethanol were coated on a 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 picture is adhered on top of this, and a metal halide lamp is used for 60 minutes from a distance of 0.8 m.
Exposure for 2 seconds and development with the following developer gave 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

In the lithographic printing plate thus obtained, the edge of the positive film remained thinly as an image on the plate surface. Meanwhile, the modifying agent of the present invention was prepared as follows. First,
A random copolymer (molecular weight of about 3) obtained by free radical polymerization of vinylpyrrolidone / vinyl acetate copolymer (70:30) in a liquid obtained by mixing 60.0 parts of γ-butyrolactone, 20 parts of benzyl acetate, and 4 parts of pure water. 0.0000) was dissolved in 3.0 parts, and then oxyethyleneoxypropylene block polymer (polypropylene glycol having an average molecular weight of 2,000 was polymerized with ethylene oxide at both ends. Molecular weight: 10,000, ethylene oxide content : 80%)
8.5 parts were dispersed. 2 parts of phosphoric acid (85%) and 0.003 parts of crystal violet were added, and sufficiently stirred to obtain a uniform solution. To this, 4.0 parts of powdered silicon dioxide was added and dispersed to obtain a viscous modifier. The pH of this modifier was 1.46 at 25 ° C. The prepared correction agent 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 and washed off. When the water is sprayed, the area where the correcting agent is applied changes to a cloudy state once, and when the water is further sprayed, it is easily washed off and removed from the printing plate. That is, since the desired image portion can be quickly corrected without affecting the required image portion without scattering to the required image portion, the device has excellent suitability for automatic washing machine. In the printing plate, the image portion due to the edge of the film cut,
The hydrophilic layer was completely exposed and could not be distinguished from other non-image areas.

The plate thus corrected was gummed with a 14 ° Be aqueous solution of gum arabic, and mounted on an offset printing machine to print 10,000 sheets. No stain was observed on the erased image area. A beautiful print was obtained. The correction agent of the present invention can be repaired with confidence because the bleeding of the liquid is very small even when erasing details, and it is highly safe and uncomfortable in physiological terms and has excellent usability. Was. Thereafter, Examples 2 to 5 were prepared in the same manner as in Example 1 to obtain a modifier of the present invention. Using this, erasing was performed in the same manner as in Example 1, but the results were all good. Further, as a forced aging test, deterioration of erasability was examined after storing the modifying agent for 7 days at 50 ° C./80% RH, and all were good as in the case of the new solution.

Example 2 Part γ-butyrolactone 50.0 Cyclohexyl acetate 22.0 Phosphoric acid (85%) 7.0 Vinyl methyl ether / maleic anhydride 0.5 (1: 1 molar ratio) ) Copolymer (Gantrez S-95 (ISP)) Alkylated polyvinylpyrrolidone ... 1.0 (Ganex (ISP)) Sodium alkylbenzenesulfonate ... 0.5 Oxyethyleneoxypropylene block ... 5.0 Polymer The same as that used in Example 1.) Pure water 10.0 Crystal billet 0.003 Powdered silicon dioxide 4.0 The pH of this modifier was 1.55 at 25 ° C.

Example 3 Part Benzyl acetate 48.8 γ-butyrolactone 10 Cyclohexanone 5 Xylene 7.0 Phosphoric acid (85%) 5.0 Methyl cellulose (methoxy group: 27 to 2) 0.032%, viscosity of 2% aqueous solution at 20 ° C. is 550 to 750 cps) Vinylpyrrolidone / vinyl acetate copolymer 1.0 ((80:20) copolymerized, molecular weight about 1. 50,000) Oxyethylene oxypropylene block ... 5.0 Polymer (same as used in Example 1) Lauryl alcohol sulfate ... 0.2 Sodium salt Water ... 11.2 Dye (CI Basic Red 2) 0.0005 powdered silicon dioxide ... 5.0 The pH of this modifier was 1.71 at 25 ° C.

Example 4 Part Benzyl acetate 29.5 n-butyl propionate 30.0 Petroleum fraction (boiling point: 160 to 180 ° C., 10.0 alkylbenzenes having 8 to 11 carbon atoms) Phosphoric acid (85%) 5.0 Oxyethyleneoxypropylene block 10.0 Polymer (HLB: 12) Alkylated polyvinylpyrrolidone 0.5 (Same as in Example 2) Vinylpyrrolidone / vinyl Acetate copolymer 1.0 ((80:20), the same as in Example 3) Pure water 9.0 A dye (CI Basic Red 2, 50240) 0.005 powdered silicon dioxide 5 0.0 The pH of this modifier was 1.78 at 25 ° C.

Example 5 Part Benzyl acetate 40.0 Butyl lactate 15.0 Cyclohexanone 7.0 Toluene 5.0 Xylene 5.0 Phosphoric acid (85%) 3.0 Silicon Hydrofluoric acid (20%) ... 1.0 Alkylated polyvinylpyrrolidone ... 1.0 (same as in Example 2) Hydroxypropylcellulose ... 1.0 (Hydroxypropoxy group: 77.5%) Oxyethylene Oxypropylene block ... 4.0 Polymer (same as used in Example 1) Oxyethyleneoxypropylene block ... 4.0 Polymer (HLB: 16) Pure water ... 9.0 Dye (CI Basic Blue) 9, 52015) 0.007 powdered silicon dioxide 5.0 The pH of this modifier was 1.72 at 25 ° C.

Comparative Example 1 γ-butyrolactone 80.0 parts Pure water 4.0 Hydroxypropyl methylcellulose 1.5 (same as in Example 1) Oxyethyleneoxypropylene block 8.5 polymer Phosphoric acid (85%) 2 Powdered silicon dioxide 4

Comparative Example 2 Methyl carbitol 23 parts Cyclohexanone 38 Dioxane 10 Water 10 Phosphoric acid 5 Hydroxypropyl methylcellulose 5 1.5 Same as Comparative Example 1 Oxyethyleneoxypropylene Block 8.5 Polymer (same as Comparative Example 1) Powdered silicon dioxide 4

Performance comparison tests were carried out on the modifiers of Examples 1 to 5 and Comparative Examples 1 and 2. The evaluation method for each test item is as follows. Table 1 shows the test results. Erasability: In an erasing operation in which a correcting agent is applied to an image portion and left for a certain period of time, and then the correcting agent is washed away with water, if the above-mentioned leaving time is changed in a range of 10 seconds to 60 seconds in increments of 10 seconds, the number of seconds. Was used to determine whether the erasure of the image area was completed, and evaluated according to the following criteria. A: Within 10 seconds. B: longer than 10 seconds and within 20 seconds. C: longer than 20 seconds and within 30 seconds. D: longer than 30 seconds. Easiness of bleeding: 30% The correction agent is applied at an interval of 1 mm, 2 mm or 3 mm from the boundary of the halftone dot image area, left for 10 minutes, washed with water, and examined for erosion of the halftone dot image. A: There is no effect even if it is applied 1 mm apart. B: There is an effect at 1 mm interval, but there is no effect at 2 mm interval. C: There is an effect even at 3 mm interval.

Suitability for automatic washing machine: A film is stuck on a chrysanthemum whole size plate, eight film edges are corrected, and the effect of necessary image portions after washing with an automatic washing machine is examined. Conditions: water washing machine; manufactured by Shinwa Kogyo Co., Ltd. Water volume; 5 to 8 liters / min. Conveying speed: 0.6 to 1.0 m / min. A: No influence on required image area. B: Color loss in minute image area is observed. C: Influenced Stability over time: The modifier was allowed to stand at 50 ° C./80% RH for 7 days, and then evaluated by the same evaluation as “erasability”. Odor: A: None B: Slightly present C: Yes

[0047]

[Table 1]

Claims (1)

[Claims] 1. The following general formula [I], [II] or [III]
A modifier for a lithographic printing plate comprising at least one compound represented by the formula: Embedded image (Wherein [I], R ¹ represents a hydrogen atom or a methyl group, R ²
Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
And m and n are values that result in a molecular weight of 3,000 to 50,000. In the formula [II], R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 9 carbon atoms, provided that all R ³ , R ⁴ on the polymer chain , R ⁵ and R ⁶ do not represent a hydrogen atom, and o has a molecular weight of 5000
It is a value that becomes ５０50,000. In the formula [III], R ⁷ represents a hydrogen atom or a methyl group, R ⁸ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkali metal or NH ₄ ,
And p and q are values that result in a molecular weight of 80,000 to 250,000. )