JPH053583B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a correcting agent for lithographic printing plates, and more particularly to a correcting agent used for erasing unnecessary image areas (areas that receive printing ink) of lithographic printing plates.

[Conventional technology]

In lithographic printing plates, such as those produced by photolithography, undesirable images or portions of the image that need to be deleted or corrected may inevitably occur and need to be corrected. For example, dirt, scratches, cuts, etc. on the original film may cause overexposure or underexposure on the printing plate surface, resulting in unnecessary image areas that must be corrected. As a correcting agent for removing unnecessary image areas of such a lithographic printing plate, for example, (a) glycol, polyglycol, glycol ether or polyglycol ether 20 to 60% by weight, as described in Japanese Patent Publication No. 16047/1982; (b) Neutral organic solvents other than those listed in (a) 10 to 50% by weight, (c) Water 3 to 25% by weight, (d) Acidic substances 0.5 to 15% by weight, (e) Thickening agents 5 to 50% by weight. a composition containing 25% by weight;
In addition, (a) organic solvent 50 described in JP-A-54-89806
~90% by weight, (b) 3-20% by weight of surfactant, (c) 0.5-5% by weight of gum arabic, (d) 0.5-15% by weight of phosphoric acid.
There are compositions containing. However, in recent years, there has been a trend toward higher printing durability (increased printing durability) of lithographic printing plates, and the strengthening of image areas has lowered the solubility in correction agents, making corrections increasingly difficult. To give a specific example, even if a conventional correction agent was used, the image area was not completely erased and remained. Particularly, it is difficult to erase so-called halftone areas, and printing ink tends to adhere to these areas during printing, causing stains on the printed matter. In addition, there was a strong desire to speed up the correction work, and the conventional performance was no longer sufficient.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a lithographic printing plate corrector that can quickly erase unnecessary image areas. Another object of the present invention is to provide a correcting agent for lithographic printing plates that is highly erasable in halftone areas. Still another object of the present invention is to provide a correction agent that can completely erase unnecessary image areas of a high printing durability type lithographic printing plate with strong image areas and speed up correction work.

[Structure of the invention]

The inventors of the present invention have conducted intensive research to achieve the above object, and as a result, they have achieved the present invention. At least one selected compound has the general formula () H(-O-R ₁ )- _o O-R ₂ (wherein R ₁ is an alkylene group having 2 to 3 carbon atoms,
_R2 represents a phenyl group or a tolyl group, and n represents an integer of 1 to 3. ) General formula () (However, R ₃ represents a hydrocarbon divalent group having 2 or more carbon atoms.) A correcting agent for a lithographic printing plate characterized by containing benzyl alcohol, and hydrofluoric acid. The modifying agent of the present invention containing at least one compound selected from the compounds satisfying the structure of the above general formula () or (), benzyl alcohol, and hydrofluoric acid is a conventionally known modifying agent. It has been found that the eraseability is significantly higher than that in comparison, and that it has excellent performance that does not have any adverse effect on adjacent drawings (necessary drawings close to the image to be erased). Particularly, what cannot be erased even when conventional correcting agents are used in high printing durability type lithographic printing plates can be completely removed for the first time by the correcting agent of the present invention. The present invention will be explained in detail below. Specific examples of compounds satisfying the general formula () contained in the modifier of the present invention include ethylene glycol monophenyl (or tolyl) ether, propylene glycol monophenyl (or tolyl) ether, trimethylene glycol monophenyl (or tolyl) ether, diethylene glycol monophenyl (or tolyl) ether, dipropylene glycol monophenyl (or tolyl) ether, di-trimethylene glycol monophenyl (or tolyl) ether, triethylene glycol monophenyl (or tolyl) ether, tripropylene Examples include glycol monophenyl (or tolyl) ether, tri(trimethylene glycol) monophenyl (or tolyl) ether, and the like. Specific examples of compounds satisfying the general formula () include α-
Phenylethyl alcohol and its derivatives such as phenylethyl alcohol, β-phenylethyl alcohol, α,β-dioxyethylbenzene, 1-
Phenyl-1-propanol, 2-phenyl-2
-propanol, phenylpropanol and its derivatives such as 2-phenyl-1-propanol, 3-phenylpropanol, 2,2'-(para-phenylene)-di-2-propanol, 4-phenyl-1-butanol, Examples include phenylbutanol such as 4-phenyl-2-butanol and derivatives thereof. In addition to those in which R ₃ in the above general formula () is a saturated hydrocarbon group, there are also those in which R ₃ is an unsaturated hydrocarbon group such as 1-phenyl-2-propyn-1-ol and cinnamyl alcohol. Can be mentioned. Also included are compounds having the structure of the above general formula () or () substituted with a halogen atom such as fluorine, bromine, chlorine, or iodine, or a substituent such as a hydroxyl group or an alkoxy group. In the general formula (), R ₃ is preferably a divalent hydrocarbon group having 2 to 6 carbon atoms, more preferably 2 to 4 carbon atoms. Among the compounds that satisfy the structure of general formula () or () listed above, ethylene glycol monophenyl (or tolyl) ether, propylene glycol monophenyl (or tolyl) ether, trimethylene glycol monophenyl (or tolyl) Ether, α-phenylethyl alcohol, β-phenylethyl alcohol, 1
-Phenyl-1-propanol, 2-phenyl-
2-pyropanol, 3-phenylpropanol,
4-phenyl-2-butanol, 1-phenyl-
2-propyn-1-ol and cinnamyl alcohol are preferred because they have high erasability in image areas. More preferred are ethylene glycol monophenyl ether, propylene glycol monophenyl ether, α-phenylethyl alcohol, β-phenylethyl alcohol, and phenylpropanol. In addition, R ₃ in the above general formula () is an unsaturated carbon group, especially 1-phenyl-2propyne-
1-ol, cinnamyl alcohol, etc. are preferable because they have good halftone erasing properties. The compound satisfying the structure of the above general formula () or () (hereinafter referred to as the first essential component of the present invention) can be used alone or in combination of two or more, and can be used as the modifier of the present invention. The content is suitably 5 to 80% by weight based on the total weight, more preferably 10 to 70% by weight, and most preferably 30 to 60% by weight. Benzyl alcohol, which is the second essential component of the modifier of the present invention, is suitably contained in an amount of 5 to 80% by weight, more preferably 10 to 70% by weight, most preferably 10 to 70% by weight, based on the total weight of the modifier of the present invention. It is preferably contained in a range of 15 to 60% by weight. Hydrofluoric acid, which is the third essential component of the correction agent of the present invention, is contained in an amount of 0.1 to 10% based on the total weight of the correction agent of the present invention.
It is suitable to contain % by weight, more preferably 0.3 to 5% by weight, most preferably 0.5 to 4% by weight.
It can be contained within the range of. More preferable configurations of the correcting agent of the present invention include:
Contains at least one compound satisfying the structure of the above general formula (), at least one compound among the compounds satisfying the structure of the above general formula (), benzyl alcohol, and hydrofluoric acid. It is something to do. The most preferable configuration is the above general formula ()
Compounds satisfying the structure and the above general formula ()
and a compound in which R ₃ is a saturated hydrocarbon group, and a compound which satisfies the structure in the general formula () above and in which R ₃ is an unsaturated carbonized group, at least one of each, and benzyl alcohol and It contains hydrofluoric acid. The modifier of the present invention further includes organic solvent compounds other than the first and second essential components of the present invention, acidic substances other than hydrofluoric acid, water, thickeners, surfactants,
Coloring dyes and the like can be selectively added, thereby further enhancing the modifier performance.
These will be explained in detail below. Examples of organic solvent-based compounds other than the first and second essential components of the present invention include ethers,
These include fatty acids and other hydrocarbon solvents. Typical ethers are glycol ethers, specifically ethylene glycol monoalkyl ethers such as methyl, ethyl, isopropyl, and butyl ethers of ethylene glycol, and ethylene glycol dialkyl ethers such as methyl diethylene glycol. -,
diethylene glycol monoalkyl ethers such as ethyl, isopropyl, and isobutyl ether; diethylene glycol dialkyl ethers such as methyl of triethylene glycol;
Triethylene glycol monoalkyl ethers such as ethyl and butyl ether, triethylene glycol dialkyl ethers, e.g. ethylene glycol monomethyl ether acetate, ethylene glycol monoalkyl ether acetate such as ethylene glycol monomethyl ether acetate, e.g. polyoxyalkylene aryl ethers , polyoxyalkylene alkylaryl ethers. As ketones,
For example, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl amyl ketone,
Examples include methylhexylketone, diethylketone, ethylbutylketone, butylone, valerone, diisopropylketone, mesityl oxide, acetylacetone, acetonylacetone, cyclohexanone, ethyl acetoacetate, methylcyclohexanone, acetophenone, and the like. Examples of lactones include butyrolactone, valerolactone, and hexanolactone. Examples of alcohols include alicyclic alcohols, aliphatic monohydric alcohols, and polyhydric alcohols. Alicyclic alcohols include, for example, cyclohexanol, cyclopentanol, terpene alcohols, and sterols such as lanolin. Aliphatic monohydric alcohols include, for example, methyl alcohol, ethyl alcohol, propanol, butanol, pentanol,
Saturated aliphatic monohydric alcohols represented by hexanol, heptanol, octanol, nonol, decanol, undecanol, dodecanol, tridecanol, hexadecanol, octadecanol, etc., such as allyl alcohol, oleyl alcohol, elaidyl alcohol, linoleyl alcohol, There are unsaturated aliphatic monohydric alcohols represented by linolenyl alcohol, geraniol, propargyl alcohol, etc. Polyhydric alcohols include ethylene glycol, propanediol,
Examples include dihydric alcohols such as dihydric alcohols such as glycerin, trihydric alcohols such as glycerin, and polyglycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and diglycerin. Examples of fatty acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid,
These include saturated fatty acids such as capric acid, pelargonic acid, capric acid, undecylic acid, and lauric acid, and unsaturated fatty acids such as acrylic acid, crotonic acid, bodecylenic acid, oleic acid, linoleic acid, ricinoleic acid, and linolenic acid. Examples of other hydrocarbon solvents include petroleum fractions with boiling points around 120 to 250°C, toluene, xylene, benzene, turpentine oil, kerosene, and N-
Lactams such as methylpyrrolidone, N,N-
dimethylformamide, dimethyl sulfoxide,
Tetrahydrofuran, dioxane acetic anhydride, etc.
There are various examples. Preferred organic solvent-based compounds other than the first and second essential components of the present invention listed above include glycol ethers, ketones, lactones, alcohols, and other hydrocarbon-based solvents. . Among them, ethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, diethylene glycol monoalkyl ethers, diethylene glycol dialkyl ethers, diisopropyl ketone, mesityl oxide, cyclohexanone, methylcyclohexanone, butyrolactone, valerolactone, hexanolactone, xylene. , N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, and dioxane are more preferred because they have a high erasing speed in the image area. Most preferred are ethylene glycol monoalkyl ethers, diethylene glycol monoalkyl ethers, cyclohexanone, methylcyclohexanone, dimethyl sulfoxide, and tetrahydrofuran. The organic solvent-based compounds other than the first and second essential components of the present invention can be used alone or in combination of two or more, and have a 5 to 85
The content is preferably in the range of 20 to 80% by weight, most preferably 35 to 70% by weight. Examples of acidic substances other than hydrofluoric acid include hydrochloric acid, sulfuric acid, persulfuric acid, phosphoric acid, nitric acid, permanganic acid,
Inorganic acids such as borofluoric acid and hydrofluorosilicic acid; organic acids such as citric acid, malic acid, lactic acid, oxalic acid, trichloroacetic acid, tannic acid, phytic acid, P-toluenesulfonic acid, and phosphonic acid; There are salt, etc. 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)pyridine, aminotri(methylenephosphonic acid), vinylphosphonic acid, polyvinylphosphonic acid, 2-phosphonoethane-1-sulfonic acid, water-soluble copolymers of vinylphosphonic acid and acrylic acid and/or vinyl acetate, etc. can be mentioned. Among these acidic substances, phosphoric acid, borofluoric acid, hydrosilicic acid, phosphonic acid, and salts thereof are preferred for improving the correction effect, and phosphoric acid and borofluoric acid are more preferred. These acidic substances can be used alone or in combination of two or more, and are in the range of 0.1 to 10% by weight, preferably 0.3 to 5.0% by weight, particularly preferably 0.5 to 3.0% by weight based on the total weight of the modifier. Contained. Water is contained in various components such as acids, and in addition to being necessarily added, water may be added selectively, but it has a subtle effect on the performance of the modifier of the present invention. Therefore, the preferable addition amount is 1 to 30% by weight, more preferably 3 to 20% by weight, based on the total weight of the correcting agent. Examples of thickeners include inorganic thickeners such as silicic acid fine powder, modified celluloses such as methylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose/Na salt, gum arabic,
Polymer compounds such as polyvinyl pyrrolidone, polyvinyl methyl ether, polyethylene glycol, polypropylene glycol, and vinyl methyl ether-maleic anhydride copolymer are exemplified. Among these, modified cellulose, polyvinylpyrrolidone, and the above-mentioned two types of maleic anhydride copolymers are preferred, and modified cellulose such as hydroxypropyl methylcellulose and polyvinylpyrrolidone are most preferred. These thickeners can be used alone or in combination of two or more, and the amount added can be changed to achieve the desired viscosity, but preferably 0.5 to 25% by weight based on the modifier of the present invention. More preferably, it is used in an amount of 1 to 15% by weight. As surfactants, polyoxyethylene alkyethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystylphenyl ether, polyoxyethylene polyoxypropylene alkyl ether, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, Pentaerythritol fatty acid partial esters,
Propylene glycol monofatty acid ester, sucrose fatty acid ester, oxyethylene oxypropylene block copolymer, polyoxyethylene sorbitan fatty acid partial ester, polyoxyethylene sorbitol fatty acid partial ester, polyethyl glycol fatty acid ester, polyglycerin fatty acid partial ester , polyoxyethylenated castor oils, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N,N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, trialkyl Nonionic surfactants such as amine oxy, fatty acid salts, abitiate salts, hydroxyalkanesulfonates, alkanesulfonates, dialkyl sulfosuccinate salts, linear alkylbenzene sulfonates, branched chain alkylbenzene sulfonates, Alkylnaphthalene sulfonates, alkyl phenoxypolyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium, N-
Alkyl sulfosuccinic acid monoamide disodium salts, petroleum sulfonates, sulfated castor oil, sulfated beef leg oil, sulfate ester salts of fatty acid alkyl esters, alkyl sulfate ester salts, polyoxyethylene alkyl phenyl ether sulfate ester salts, polyoxy Ethylene alkyl ether sulfate ester salts, fatty acid monoglyceride sulfate ester salts, polyoxyethylene alkyl phenyl ether sulfate ester salts, polyoxyethylene stylphenyl ether sulfate ester salts, alkyl phosphate ester salts, polyoxyethylene alkyl ether phosphate ester salts , polyoxyethylene alkyl phenyl ether phosphate ester salts, partially saponified products of styrene-maleic anhydride copolymer, partially saponified products of olefin-maleic anhydride copolymer, naphthalene sulfonate formalin condensates, etc. Anionic surfactants, alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, cationic surfactants such as polyethylene polyamine derivatives, carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric acid Examples include amphoteric surfactants such as esters and imidazolines. Among the surfactants listed above, polyoxyethylene can also be read as polyoxyalkylene such as polyoxymethylene, polyoxypropylene, and polyoxybutylene. Among these, nonionic surfactants and anionic surfactants are preferred, and surfactants with an HLB of 9 or more are more preferred because the synthetic components contained in the modifier can be mixed well. Furthermore, polyoxyethylene alkyl phenyl ethers, oxyethylene oxypropylene block copolymers, polyoxyethylene sorbitan fatty acid partial esters,
Polyoxyethyl sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, and polyglycene fatty acid partial esters are preferable in order to improve the image area erasing effect of the correcting agent. Most preferred is oxyethylene oxypropylene block copolymer. These surfactants may be used alone or in combination of two or more, and are contained in an amount of 1 to 40% by weight, preferably 3 to 25% by weight, based on the total weight of the modifier of the present invention. Colored pigments can be included if visual contrast is desired, and specifically include, for example, crystal violet, safranin, brilliant blue, malachite green, acidrhodamine B.
There are dyes such as, inorganic pigments, organic pigments, etc. These colorants are present in an amount of 0.0001 to 0.05% by weight, preferably 0.001% by weight, based on the total weight of the corrective agent according to the invention.
It is used in a range of 0.01% by weight. The correcting agent of the present invention can be applied to positive-working and negative-working photosensitive planographic printing plates (hereinafter referred to as RS plates), and in particular, planographic printing plates obtained by plate-making from PS plates having a negative-working photosensitive layer on a support. It is advantageously used when correcting and erasing the image portion of the image. These PS versions will be explained in detail below. The support for the PS plate used in the present invention is a dimensionally stable plate-like material, and includes those conventionally used as supports for printing plates. Examples of such supports include paper, paper laminated with plastics (e.g. polyethylene, polypropylene, polystyrene, etc.), aluminum plates (including aluminum alloys), zinc plates, copper plates, iron plates, composite metal plates (eg chrome Metal plates such as cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc. paper or plastic film laminated or vapor-deposited with metals such as those mentioned above, composite sheets in which an aluminum sheet is bonded to a polyethylene terephthalate film as described in Japanese Patent Publication No. 18327-1983, etc. is included. The PS plate support used in the present invention has a hydrophilic surface. Here, the term "hydrophilic surface" refers to a surface that becomes wet with dampening water and repels printing ink when the lithographic printing plate is mounted on a printing press and printed under standard conditions. It is preferable that the surface of the support is subjected to a water-immersion treatment. There are various methods for hydrophilic treatment. For example, in the case of a support having a plastic surface, methods such as chemical treatment, electric discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, activated plasma treatment, laser treatment, etc., and undercoating after these treatments are used. There is a method of applying layers. In addition, in the case of a support having a surface of metal such as aluminum, graining treatments such as brush polishing and electrolytic polishing, sodium silicate,
Examples include immersion treatment in an aqueous solution of fluoridated zirconate or phosphate, plating, coating, or anodic oxidation treatment. Among the supports mentioned above, a plate having a grained or anodized aluminum surface or an iron plate coated with chromium is preferable because the adhesion of the photosensitive layer is improved. Examples of anodizing baths include hydrochloric acid, nitric acid, chromic acid, boric acid, sulfuric acid, persulfuric acid, phosphoric acid,
Examples include aqueous solutions of various acids such as sulfamic acid and oxalic acid. A preferred anodizing bath is phosphoric acid.Aluminum plates that have been subjected to graining treatment and further anodized treatment are more preferred. An aluminum plate that has been brush-polished and further anodized, or an aluminum plate that has been brush-polished and electrolytically polished and further anodized can be obtained because it has particularly favorable adhesion to photosensitive devices.
PS plates have high printing durability, and the correction agent of the present invention is particularly advantageous. Furthermore, surface roughness is known as a method of expressing the hydrophilicity of a support, and it has been found that this surface roughness also serves as a measure of the adhesiveness of the photosensitive layer. Therefore, the center line roughness Ra [μm] is
0.40 or more, more preferably 0.50 or more and 0.80 or less.
Showing the most favorable adhesion, the preferred area is 0.60
It is more than 0.80 or less. (Measuring instrument: Peltometer, Tracer RHT3/50e, manufactured by West German Penten) The photosensitive composition of the photosensitive layer provided on the hydrophilic surface of the support contains a diazo compound, British Patent No. 1235281 A photosensitive composition containing an azide compound as described in the specifications of US Pat. No. 3,860,426 and US Pat. Patent No. 4072528 and Patent No. 4072527
A photosensitive composition containing a photopolymerizable photopolymer as described in JP-A-56-19063
photoconductive compositions as described in JP-A-52-62501 and JP-A No. 56-29250;
Examples include silver halide emulsion compositions as described in each publication No.-111852. Among these photosensitive compositions, photosensitive compositions containing a diazo compound have excellent properties such as storage stability of the photosensitive layer, development performance such as development latitude, image performance such as image quality, ink receptivity, oil sensitivity,
It is preferred because of its overall excellent printing performance such as abrasion resistance and low pollution of the developer used. Photosensitive compositions containing diazo compounds are classified into negative type and positive type. The negative-working photosensitive composition contains a photosensitive diazo compound and preferably a polymer compound. Conventionally known photosensitive diazo compounds can be used, but preferred ones include: Salts of diazo resins soluble in organic solvents, such as salts of condensates of p-diazodiphenylamine and formaldehyde or acetdehyde and hexafluorophosphates, salts of toluenesulfonates, 2-
Hydroxy-4-methoxybenzophenone-5-
Examples include salts with sulfonate salts. A particularly preferred example is the following general formula (): (In the formula, R ₄ , R ₅ and R ₆ represent a hydrogen atom, an alkyl group or an alkoxy group, R represents a hydrogen atom, an alkyl group or a phenyl group, X represents PF ₆ or BF ₄ , and m represents 1 -200), and contains 20 mol% or more, preferably 20 to 60 mol%, of a resin in which m in the formula is 5 or more. The content of the diazo resin in the photosensitive composition according to the present invention is 1 to 70% by weight, preferably 3 to 60% by weight.
It is. Examples of polymer compounds include acrylic acid or methacrylic acid copolymers, crotonic acid copolymers, itaconic acid copolymers, maleic acid copolymers, cellulose derivatives having carboxyl groups in their side chains, and cellulose derivatives having carboxyl groups in their side chains. Polyvinyl alcohol derivatives having carboxyl groups in their side chains, hydroxyalkyl acrylate or methacrylate copolymers having carboxyl groups in their side chains, unsaturated polyester resins having carboxyl groups, etc. are preferably used. More preferably, it is a polymer compound having an acid value of 10 to 300.
Further, more preferably, a structural unit represented by the following general formula () described in JP-A-50-118802 and a polymer containing a structural unit represented by the following general formula (), JP-A-57-192951 A polymer containing a monomer unit having an aromatic hydroxyl group and a structural unit represented by the general formula () as described in the above specification is used. (In the general formula, R ₇ represents a hydrogen atom or a methyl group,
(R ₈ represents a hydrogen atom, methyl group, ethyl group, or chloromethyl group, R ₉ represents a hydrogen atom or methyl group, and Q represents an integer from 1 to 10) As a diazo compound used in a positive photosensitive composition Although conventionally known compounds can be used, representative examples include o-quinonediazides, and preferably o-naphthoquinonediazide compounds. Among o-naphthoquinone diazide compounds, o-
naphthoquinonediazide sulfonic acid ester or o
-naphthoquinonediazidecarboxylic acid esters and o-naphthoquinonediazitosulfonic acid amides or o-naphthoquinonediazidecarboxylic acid amides of aromatic amino compounds are preferred. Preferred hydroxy 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 compounds include formaldehyde, benzaldehyde, and acetone. Preferred hydroxy compounds include phenol-formaldehyde resin, cresol-formaldehyde resin, pyrogallol-acetone resin, and resorcinol-bendialdehyde resin. Typical specific 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 resin. Ester, described in JP-A-56-1044 Ester of naphthoquinone-(1,2)-diazide-(2)-5-sulfonic acid and resorcinol-benzaldehyde resin, described in U.S. Pat. No. 3,635,709 ester of naphthoquinone-(1,2)-diazide sulfonic acid and pyrogallol acetone resin,
Examples include esters of naphthoquinone-(1,2)-diazide-(2)-5-sulfonic acid and resorcinol-pyrogallol-acetone copolymer condensate described in JP-A-55-76346. Other useful o
-As a quinonediazide compound, JP-A-1988-
117503, in which a polyester having a hydroxyl group at the end is esterified with o-naphthoquinonediazide sulfonyl chloride, and p-hydroxystyrene as described in JP-A-50-113305, Homopolymers or copolymers with other copolymerizable monomers are esterified with o-naphthoquinone diadosulfonyl chloride, and bisphenol formaldehyde resins and o-naphthoquinonediadosulfonyl chloride described in Japanese Patent Publication No. 54-29922 are used. - esters with quinonediazide sulfonic acid, condensates of o-quinonediazitosulfonyl chloride with copolymers of alkyl acrylates, acroyloxyalkyl carbonates and hydroxyalkyl acrylates as described in U.S. Pat. No. 3,859,099; Tokuko Showa 49-
17481, a reaction product of a copolymerization product of styrene and a phenol derivative and o-quinonediazide sulfonic acid, US Pat.
Amides of copolymers of p-aminostyrene and other copolymerizable monomers with o-naphthoquinonediazide sulfonic acid or o-naphthoquinonediazidecarboxylic acid as described in No. 3759711; Examples include esterified products of hydroxybenzophenone and o-naphthoquinonediazide sulfonyl chloride. Although these o-naphthoquinone diazide compounds can be used alone, 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 phenolic resins, specific examples of which include phenol formaldehyde resins, cresol formaldehyde resins, and phenol/cresol formaldehyde copolymer resins as described in JP-A-55-57841. etc. are included. Furthermore, as described in JP-A-50-125806, in addition to the above-mentioned phenol resin, phenol or cresol substituted with an alkyl group having 3 to 8 carbon atoms such as t-butylphenol formaldehyde resin is used. It is even more preferable to use a condensate with formaldehyde. The content of the o-quinonediazide compound is preferably 5 to 80% by weight, particularly preferably 10 to 50% by weight, based on the solid content of the photosensitive composition. The content of the alkali-soluble resin is preferably 30 to 90% by weight, particularly preferably 50 to 85% by weight, based on the total solid content of the photosensitive composition. The photosensitive composition can be provided in multiple layers, and additives such as dyes, plasticizers, and components imparting printout performance can be added as necessary. The coating amount of the photosensitive composition provided on the support is preferably 0.1 to 7 g/m ² , more preferably
It is 0.5 to 4 g/ ^m2 . The modifier of the present invention becomes more effective at 1.5 to 4 g/m ² , and most effective at 2.0 to 3.0 g/m ² . The PS plate thus obtained is exposed through a transparent cost to a light source rich in actinic light such as a carbon arc lamp, mercury lamp, metahalide lamp, tungsten lamp, xenon lamp, etc., and then developed. The developer used may vary depending on the type of photosensitive composition used in the PS plate, but preferably contains at least one of an alkaline agent and an organic solvent. This is described in detail in Japanese Unexamined Patent Publication No. 59-58431. The developing solution for PS plates with a negative-working diazo photosensitive layer, which is widely used, generally contains ethylene glycol monophenyl ether and benzyl alcohol; In ratio [SiO ₂ ]/
[M] = 0.5 to 1.5 ([SiO ₂ ] and [M] represent the molar concentration of SiO ₂ and the molar concentration of total alkali metals such as K, Na, and Li, respectively), and SiO ₂ is 0.8 to 1.5. Generally, it contains 8% by weight. Methods for developing the image-exposed PS plate with the developer described above include jetting the developer from multiple nozzles, immersing it in the developer, and wiping with a sponge moistened with the developer. Various methods known in the art are possible. As mentioned above, if there is an unnecessary image area on the lithographic printing plate obtained by performing image exposure and development on the PS plate, the image area can be erased by applying the correction agent of the present invention on the image area. Ru. When the correcting agent of the present invention is applied to the image area of a lithographic printing plate, it is preferable to wash the plate with water after development and use a squeegee to remove the washing water before erasing the plate. A specific method for erasing is to soak a brush in a correction agent, apply it to the image area, leave it for about 10 seconds to several minutes, or lightly rub it with a brush after application, and then wash it off with water. Alternatively, a common method is to rinse it off and simultaneously rub it with a sponge. The lithographic printing plate from which unnecessary image areas have been erased in this manner is subjected to ordinary processing steps such as development inking or gumming, and is then subjected to printing. The correction agent of the present invention can completely erase unnecessary image areas and eliminate troubles during printing due to incomplete erasure, thereby improving printing efficiency. Furthermore, the correcting agent of the present invention can easily and quickly erase unnecessary image areas, and has high erasability in halftone areas, so that the efficiency of plate-making work is improved. Furthermore, the correcting agent of the present invention has high adhesive strength between the support and the photosensitive layer, and also has extremely high erasability of PS plates with high printing durability. EXAMPLES Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.
In addition, in the following examples, "part" represents a part by weight, and "%" means weight %. Example 1 An aluminum plate with a thickness of 0.30 mm was polished with a nylon brush and anodized in a phosphoric acid bath. At this time, the amount of oxide film on the aluminum plate was 11 mg/dm ²
It was hot. Further, the pores were sealed with an aqueous sodium metasilicate solution to obtain a support for a lithographic printing plate. The center line average roughness Ra of this material was 0.62 to 67. A photosensitive solution having the following composition was applied to this support, and then dried at a temperature of 90°C for 2 minutes to give a photosensitive layer thickness of 23 mg/
dm ² , a negative PS plate with good adhesion between the photosensitive layer and the support and high printing durability was obtained. (Photosensitive liquid) Copolymer 320 parts Diazo resin 26 parts Victoria Pure Blue BOH (Hodogaya Chemical Co., Ltd.)
) 6 parts Dulymer AC-10L (acrylic acid polymer manufactured by Nippon Pure Chemical Industries, Ltd.) 6 parts methyl cellosolve 3000 parts However, the above copolymer resin has a weight ratio of p-hydroxyphenylmethacrylamide/acrylonitrile/ethyl acrylate /methacrylic acid=8/
It has a composition (molar ratio) of 24/59.5/8.5 and an average molecular weight (Mw) of 5.8×10 ⁴ , and the diazo resin is a hexafluorophosphate of a condensate of p-diazodiphenylamine and rose formaldehyde. (Mw=
2.80×10 ³ , m=5 or more in the general formula [] is 35
(mol%). A halftone photographic transparent negative was placed on top of this and exposed for 50 seconds from a distance of 0.8 m using the metal halide lamp and Idolfin 2000, followed by development with the following developer to obtain a printing plate. (Developer) Benzyl alcohol 5.0 parts Sodium carbonate 0.5 parts Sodium sulfite 0.5 parts 3-methyl-3-methoxybutanol 26.5 parts Water 100 parts Next, unnecessary image areas were erased with the following correction agent of the present invention, and the result was 60 parts. It was possible to erase it in seconds. (Correcting agent of the present invention) Ethylene glycol monophenyl ether 30 parts Benzyl alcohol 40 parts Hydroxypropyl methylcellulose 3 parts 55% hydrofluoric acid 3 parts Oxyethylene oxypropylene block copolymer 5 parts Water 11 parts Example 2 Thickness 0.24 An aluminum plate of 1.5 mm in diameter was degreased by immersing it in a 20% aqueous sodium phosphate solution, electrolytically polished in a 0.2 N hydrochloric acid bath at a current density of 3 A/m ² , and then anodized in a sulfuric acid bath. At this time, the amount of anodic oxidation is
It was 3.0g/ ^m2 . Further, the pores were sealed with an aqueous sodium metasilicate solution to obtain a support for a lithographic printing plate. A photosensitive liquid having the following composition was applied to this aluminum plate. Then, it was dried for 2 minutes at a temperature of 90℃.
A negative PS plate with a film thickness of 18 mg/dm ² and easy to erase was obtained. (Photosensitive liquid) Copolymer 5.0 parts Diazo resin 0.5 parts Victoria Pure Blue BOH (Hodogaya Chemical Co., Ltd.)
Co., Ltd.) 0.1 part Methyl cellosolve 100 parts However, the same copolymer resin and diazo resin as in Example 1 were used. A halftone photographic transparent negative was placed on top of this, and exposure was carried out in the same manner as in Example 1, and development was carried out in the same manner. When the unnecessary image area of the obtained printing plate was erased with the correction agent of Example 1, it was erased within 10 seconds. Furthermore, when erasing was attempted by replacing ethylene glycol monophenyl ether with methyl carbitol in the components of the corrector used in Example 1, it took about 30 seconds to complete erasing. Furthermore, when the image area of the high printing durability printing plate used in Example 1 was erased using this correction agent, 5.
Even after several minutes had passed, the data could not be completely erased. Example 3 An aluminum plate with a thickness of 0.30 mm was polished with a nylon brush and anodized in a phosphoric acid bath. At this time, the amount of oxide film on the plate was 13 mg/dm ² and the center line average roughness Ra was 0.49 to 0.60. A photosensitive liquid having the following composition was coated on this support and dried in the same manner as in Example 1 to give a photosensitive layer thickness of 15 mg/dm ² to obtain a negative PS plate with high adhesiveness between the photosensitive layer and the support. (Photosensitive liquid) Copolymer 320 parts Diazo resin 26 parts Victoria Pure Blue BOH 6 parts Dyurimer AC-10L (manufactured by Nippon Pure Chemical Industries, Ltd.) 6 parts Methyl cellosolve 3000 parts The above copolymer and diazo resin are examples It is the same as 1. It was exposed to light in the same manner as in Example 1, and developed with the following developer to obtain a printing plate. (Developer) Diethanolamine 25.0 parts Sodium sulfite 10.0 parts Benzyl alcohol 2.0 parts Water 152 parts Next, unnecessary image areas were erased using the following correction agent of the present invention, and it was possible to erase them in 30 seconds. (Correcting agent of the present invention) Benzyl alcohol 20 parts β-phenylethyl alcohol 50 parts Hydroxypropyl methyl cellulose 4.5 parts 55% hydrofluoric acid 1.8 parts 1-hydroxyethylidene-1,1-diphosphonic acid 2,2 parts oxyethyleneoxy Propylene block copolymer 8 parts Water 11 parts Pigment (Food Blue 101) 0.002 parts Example 4 The following modifier having a composition similar to that described in Japanese Patent Publication No. 46-16047 (Example 6) was prepared, and the composition obtained in Example 2 was prepared. When the image area of the printing plate was erased, it could not be erased even after 5 minutes had passed. (Known correction agent) Triethylene glycol 43 parts Methyl ethyl ketone 34 parts Water 9 parts 40% hydrofluoric acid 2 parts Silicic acid 12 parts Pigment (Food Blue 101) 0.002 parts Example 5 Printing plate obtained in the same manner as Example 1 When unnecessary image areas were erased using the following correction agent of the present invention,
Erasing was possible in 30 seconds, and halftone areas were also erased well. (Modifier of the present invention) Ethylene glycol monophenyl ether 15 parts β-phenylethyl alcohol 30 parts Cinnamyl alcohol 10 parts Benzyl alcohol 20 parts Hydroxypropyl methyl cellulose 3 parts 55% hydrofluoric acid 3 parts Oxyethylene oxypropylene block Copolymer 7 parts Water 11 parts Pigment (Food Blue 101) 0.002 parts Example 6 When the unnecessary image area of the printing plate obtained in the same manner as in Example 1 was erased with the following correction agent, after 10 minutes I also couldn't delete it. (Correcting agent) Ethylene glycol monoethyl ether 20 parts Methyl isobutyl ketone 15 parts Dimethyl sulfoxide 10 parts Benzyl alcohol 15 parts Silicic acid 15 parts 85% phosphoric acid 15 parts Water 10 parts Example 7 Print obtained in the same manner as in Example 1 When I erased the unnecessary image part of the plate with the following correction agent, the erasing time was 5.
Not only was it time consuming, but since the halftone area was not completely erased, printing ink adhered to this area during printing, causing stains on the printed matter. (Modifier) Diethylene glycol dimethyl ether 20 parts Ethylene glycol monoethyl ether 5 parts Cyclohexane 46 parts Hydroxypropyl methylcellulose 7 parts 55% hydrofluoric acid 3 parts Oxyethylene oxypropylene block polymer 8 parts Water 11 parts Example 8 Thickness: 0.3 mm The surface of the aluminum plate 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 surface of the aluminum plate. After washing with water and drying, 3 parts of an esterified product of resorcin benzaldehyde resin and naphthoquinone 1,2-diazide-5-sulfonyl chloride synthesized according to the example of JP-A-56-1044 and 9 parts of cresol-formalin novolak resin. A photosensitive solution prepared by dissolving 0.12 parts of Victoria Beautiful Blue BOH (manufactured by Hodogaya Chemical Industry Co., Ltd.) in 100 parts of 2-methoxyethanol was coated onto the above support using a rotary coater and dried ^. A positive PS plate having a photosensitive layer of (Developer) Potassium silicate A (SiO ₂ 26%, K ₂ O 13.5%) 120 parts 86% potassium hydroxide 15.5 parts Water 500 parts Next, unnecessary image areas are erased with the following correction agent of the present invention. When I did that, it was completely erased in 15 seconds. (Modifier of the present invention) Ethylene glycol monophenyl ether 5 parts Benzyl alcohol 10 parts Xylene 9 parts Dioxane 5 parts Dimethylformamide 10 parts Cyclohexanone 20 parts Hydroxypropyl methylcellulose 1.2 parts Silicon dioxide 6.5 parts 55% Hydrofluoric acid 1.2 parts Oxyethylene Oxypropyne block copolymer 12 parts Water 10 parts Example 9 In the ingredients of the modifying agent used in Example 8, the hydrofluoric acid was replaced with 2 parts of 85% phosphoric acid and prepared in the same manner as in Example 8. When the image part of the resulting print was erased, it took more than 60 seconds to completely erase it. From the above, it can be seen that the correcting agent of the present invention can quickly and completely erase unnecessary image areas of a lithographic printing plate.

Claims (1)

[Scope of Claims] 1. A modifier for lithographic printing plates, characterized by containing at least one compound selected from the following general formula () or (), benzyl alcohol, and hydrofluoric acid. General formula () H(-O-R ₁ )- _o O-R ₂ (wherein R ₁ is an alkylene group having 2 to 3 carbon atoms,
_R2 represents a phenyl group or a tolyl group, and n represents an integer of 1 to 3. ) General formula () (However, R ₃ represents a divalent hydrocarbon group having 2 or more carbon atoms.)