JPS6224261A - Modifier for lithographic plate - Google Patents

Abstract

PURPOSE:To eliminate only an unnecessary image part by incorporating a cyclohexanone and a diethylene glycol dimethylether to the titled modifier. CONSTITUTION:The titled modifier comprises the cyclohexanone and the diethylene glycol dimethylether. The titled modifier has only a very small adverse effect for an adjacent image, and has a very rapid eliminating rate of the image part in comparison with the modifier merely contg. the cyclohexanone or the diethylene glycol dimethylether. The titled modifier has a property of preventing a strong deterioration of non-oleophilicness, after a burning treatment of an eliminated part.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a corrector for lithographic printing plates, and more specifically, for erasing unnecessary image areas (areas that receive printing ink) of lithographic printing plates. The present invention relates to a correction agent used for

(Prior Art) Lithographic printing plates For example, in lithographic printing plates such as those produced by photolithography, unnecessary images or image areas that need to be deleted or corrected may inevitably occur, making it necessary to correct them. - For example, dirt, scratches, cuts, etc. on the original film may cause overexposure or underexposure of the printing plate surface, resulting in unnecessary image areas that must be corrected.

As correcting agents for removing unnecessary image areas of such lithographic printing plates, those containing glycol ethers and lactones are disclosed in Japanese Patent Publication No. 51-33442 and Japanese Patent Application Laid-Open No. 55-121.
No. 447 Each publication contains water and is glossy. However, in recent years, there has been a high level of technical demand for correction agents, and not only high erasing speed but also an increase in correction work for minute parts. There has been an even stronger desire for something that has less adverse effects on nearby (necessary image areas that should not be erased). A further drawback of the prior art is that the insensitivity of the erased traces after burning is significantly reduced. Burning is a heat treatment to strengthen the image area after development, and it is a process that is frequently performed because it dramatically increases the number of printing plates that can be printed. A method for preventing a decrease in hydrophilicity is disclosed in JP-A-51-143409 and JP-A-52-6205, and is commonly practiced. However, the erasability of the above-mentioned overexposed and underexposed areas (hereinafter referred to as intermediate tones) is extremely poor, so not only is the erasing speed slow, but even if the above-mentioned method for preventing the decrease in hydrophilicity is applied, the burning causes the insensitivity to disappear. This causes a strong decrease in the color of the ink, making it easier to accept the development ink build-up and printing ink during printing, resulting in printing stains.

(Object of the Invention) Therefore, an object of the present invention is to provide a lithographic printing plate corrector that has extremely little adverse effect on adjacent necessary image areas and can erase only unnecessary image areas.

Another object of the present invention is to provide a lithographic printing plate corrector that does not reduce the insensitivity of erased marks regardless of whether or not burning is performed.

A further object of the present invention is to provide a lithographic printing plate corrector that has a high erasing speed in image areas and a high overall working efficiency.

(Structure of the Invention) As a result of extensive research to achieve the above object, the present inventors have completed the present invention, the gist of which is that it contains cyclohexanone and diethylene glycol dimethyl ether. It is a correcting agent for lithographic printing plates. The above correction agent of the present invention has extremely low adverse effects on adjacent images and has an extremely high erasing speed in image areas, as compared to correction agents containing cyclohexanone or diethylene glycol dimethyl ether alone. Furthermore, it has the property of preventing a strong deterioration in the insensitivity of erased traces after the burning process.

As mentioned above, the modifier of the present invention is a composition containing cyclohexanone and diethylene glycol dimethyl ether, but the effect of the present invention can be further enhanced if it further contains lactone. In particular, γ-butyrolactone is preferred. At this time, the content of each component can be used within a wide range, but it is appropriate to contain a small amount (0.5% in each case) based on the total weight of the correcting agent.

Preferred contents are -2% to 94% of each, most preferably 4 to 84% of each. In addition, as for the ratio of the above three components, the ratio of the sum of lactone and cyclohexanone to the total weight of the three components is 0.30 to 0.99.
When the erasing speed is high (preferably, 0.50 to 0.9
A value of 7 is more preferable because the ability to prevent strong deterioration of the insensitivity after erasing marks is burnt is enhanced. The most preferable composition ratio of the three components to the total weight is cyclohexanone addition to 55%, diethylene glycol dimethyl ether 5 to 22%, and lactone 35 to 70%,
In addition to the two aforementioned effects, the negative effects on adjacent drawings are particularly improved. Further, the ratio of the sum of the three types of compounds to the total organic solvent (the sum of the three types of compounds and the organic solvent-based compounds described below) in the modifier of the present invention is preferably 0.60 to 1.0, and preferably 0.70 to 1.0. 0.96 is more preferred. Most preferably it is 0.75 to 0.94.

In addition to r-butyrolactone, examples of lactones preferably used in combination in the present invention include valerolactone and hexanolactone.

In addition to the above-mentioned compounds, organic solvent-based compounds, acidic substances, water, thickeners, surfactants, coloring pigments, etc. can be selectively added to the modifier of the present invention, thereby improving the performance of the modifier. It can be further improved by 8・Leave it to us.”)L
゛rSpecific theory 0 Bjll-t6. j with an organic solvent-based compound other than the compound of the present invention; For example, there are some types of solvents, such as alcohols, fatty acids, and other hydrocarbon solvents.
do. Typical examples of ethers include glycol ethers, such as methyl, ethyl, and impropyl ethylene glycol, ethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, and ethylene glycol dialkyl ethers. Diethylene glycol monoalkyls such as methyl, ethyl, impropyl, and isobutyl ethers of diethylene glycol; diethylene glycol dialkyl ethers such as ethyl, isopropyl, and imbutyl ethers;
For example, triethylene glycol methyl, ethyl,
Triethylene glycol monoalkyl ethers such as butyl ether, triethylene glycol dialkyl ethers, e.g. engineered ethylene glycol monomethyl ether acetate, ethylene glycol monoalkyl ether acetates such as ethylene glycol monoethyl ether acetate, e.g. polyoxyalkylene aryl ethers , polyoxyalkylene alkylaryl ethers. Preferred examples of polyoxyalkylene aryl ethers and polyoxyalkylene alkylaryl ethers include ethylene glycol monophenyl (matachatoryl) ether, propylene gelylcol monophenyl (matachatoryl) ether, and diethylene glycol monophenyl (matachatoryl) ether. is tolylphether, dipropylene glycol monophenyl (
Matachatoryl) ether, triethylene glycol monophenyl (or tolyl) ether, tripropylene glycol monophenyl (or tolyl) ether, trimethylene glycol monophenyl (or tolyl) ether, di-trimethylene glycol monophenyl (or tolyl) ether , tri(trimethylene glycol) monophenyl (or tolyl) ether, and the like. Examples of ketones include methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl amyl ketone, methyl hexyl ketone, diethyl ketone, ethyl butyl ketone, butylone, valerone, diisopropyl ketone, mesityl oxide, acetylacetone, acetonyl acetone, and acetoacetic acid. Examples include ethyl, methylcyclohexanone, and acetophenone. Examples of alcohols include aromatic alcohols, alicyclic alcohols, saturated aliphatic alcohols, and polyhydric alcohols. Aromatic alcohols include aromatic hydrocarbons such as benzyl alcohol, α-phenylethyl alcohol, β-phenylethyl alcohol, tolylcarbinol, phthalyl alcohol, phenylpropyl alcohol, phenylbutyl alcohol, and vanillyl alcohol. Some have saturated side chains, and others have unsaturated bonds in the side chains of aromatic hydrocarbons, such as cinnamyl alcohol. Alicyclic alcohols include, for example, cyclohexanol, cyclopentanol, terpene alcohols, as well as saturated aliphatic alcohols such as sterine such as lanolin.
Examples of alcohols include methyl alcohol, ethyl alcohol, furopanol, butanol, pentanol,
Examples include hexanol, heptatool, octatool, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, and octadecanol.

Polyhydric alcohols include dihydric alcohols such as ethylene glycol and propanediol, and trihydric alcohols such as glycerin.

Examples of aliphatic acids include saturated fatty acids such as formic acid, acetic acid, acetic anhydride, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, and lauric acid, such as acrylic acid, There are unsaturated fatty acids such as crotonic acid, undecylic acid, oleic acid, linoleic acid, ricinoleic acid, and lilunic acid.

In addition to petroleum fractions with a temperature of around 120 to 250°C, toluene, xylene, benzene, turpentine oil, kerosene, various examples include NtN-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, N-methylpyrrolidone, and dioxane.

Among organic solvent compounds other than the compounds of the present invention, preferred are lactones, glycol ethers, ketones, aromatic alcohols, and other hydrocarbon solvents. Among them, ethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers,
Siethi V glycol monoalkyl ethers, diethylene glycol dialkyl ethers, methyl ethyl ketone, methyl propyl ketone, diisopropyl ketone,
Acetylacetone, acetonylacetone, methylcyclohexanone, lactones, benzyl acetone: F −/L/
, α-Oyobi and β-phenylethyl alcohol, xylene, N-methylpyrrolidone, N,N-dimethylformamide, dimethylsulfoxide, lactone, methyl ethyl ketone, diisopropyl ketone, xylene, N, N-
Dimethylformamide and dioxane. Organic solvent-based compounds other than the compounds of the present invention that can be selectively added as mentioned above can be used alone or in combination of two or more, and are 5 to 85% by weight, preferably 10 to 85% by weight based on the modifier of the present invention. It is contained in a range of 70% by weight.

Examples of acidic substances include hydrochloric acid, sulfuric acid, persulfuric acid, phosphoric acid,
Inorganic acids such as nitric acid, permanganic acid, and hydrofluoric 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 is salt etc.

Examples of the phosphonic acid include 1-hydroxyethylidene-1,1-diphosphonic acid and 1,2-diphosphonic-1,2-diphosphonic acid.
-dicarboxyethane, 1,2゜2.3-tetraphosphonopropane, 2(2'-phosphonoethyl)pyridine, aminotri(methylenephosphonic acid), vinylphosphonic acid,
Examples include polyvinylphosphonic acid, 2-phosphonoethane-1-sulfonic acid, and water-soluble copolymers of vinylphosphonic acid and acrylic acid and/or vinyl acetate. Among these acidic substances, phosphoric acid, hydrofluoric acid, phosphonic acid, and their salts are preferable for improving the correction effect.
More preferred are phosphoric acid and hydrofluoric acid. These acidic substances can be used alone or in combination of two or more, and are 0.1 to 10% of the total weight of the correction agent.
The content is preferably in the range of 0.3 to 5.0% by weight, particularly preferably 0.5 to 3.0% by weight.

Water is contained in various components such as acids and is necessarily added, but it can also be added selectively.
The modifier of the present invention has a subtle effect on its performance.

For this reason, the preferable amount to be added is 1 to 1 to
30% by weight, more preferably 3-20%.

Examples of thickeners include inorganic thickeners such as silicic acid fine powder, modified cellulose such as methyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose/Na salt, gum arabic, polyvinylpyrrolidone, polyvinyl methyl ether, polyethylene glycol, Examples include polymeric compounds such as polypropylene glycol, vinyl methyl ether-maleic anhydride copolymer, and vinyl acetate-maleic anhydride copolymer. 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 a mixture 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 1~
It is used in a range of 15% by weight.

As surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyrylphenyl ether, polyoxyethylene polyoxypropylene alkyl ether, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, Pentaerythol fatty acid partial esters, propylene gelicol monofatty acid esters, sucrose fatty acid partial esters, oxyethylene oxypropylene block copolymers, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acids Esters, polyglycerin fatty acid partial esters, polyoxyethylenized castor oils, polyoxyethylene glycerin fatty acid partial esters, fatty acid jetanolamides, N,N-bis-2-hydroxyalkylamines, polyoxyethylene alkyl Nonionic surfactants such as amines, triethanolamine fatty acid esters, trialkylamine oxides, fatty acid salts, avicenoates, hydroxyalkanesulfonates, and alkanesulfonates.

Dialkyl sulfonate (acid ester salts, straight chain alkyl benzene sulfonates, branched chain alkyl hense)
Lz7jt salts, alkylnaphthalene sulfonates, alkylphenoxypolyoxyethyleneprobyl sulfonates, polyoxyethylene alkylsulfophenyl ether salts, N-methyl-N-oleyl taurine sodium, N-alkylsulfosuccinic 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 ether sulfate ester salts, fatty acid monoglyceride sulfate ester salts, polyoxy Ethylene alkyl phenyl ether sulfate esters m, polyoxyethylene styryl phenyl ether sulfate ester salts, alkyl phosphate ester salts, polyoxyethylene alkyl ether phosphate ester salts, polyoxyethylene alkyl phenyl ether phosphate ester salts, styrene-maleic anhydride Partially saponified products of acid copolymers, partially saponified products of olefin-maleic anhydride copolymers, anionic surfactants such as naphthalene sulfonate formalin condensates, alkylamine salts, quaternary ammonium salts, Cationic surfactants such as polyoxyethylene alkylamine salts and polyethylene polyamine derivatives,
Examples include amphoteric surfactants such as carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfate esters, and imidacillins. Among the surfactants listed above, those mentioned as polyoxyethylene include polyoxyamethylene such as polyoxymethylene, polyoxypropylene, and polyoxybutylene. Among these, nonionic surfactants and anionic surfactants are preferable. A surfactant having an HLB of 9 or more is more preferable because the gold component contained in the modifier can be mixed well with the surfactant. Furthermore, polyoxyethylene alkyl phenyl ethers, oxyethylene oxypropylene block copolymer, polyoxyethylene sorbitan fatty acid partial esters, polyquine ethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, and polyglycerin fatty acid partial esters have been modified. This is preferable because it improves the image area erasing effect of the agent. Most preferred is oxyethylene oxypropylene prosoccopolymer. These surfactants may be contained alone or in a mixture of two or more (in a range of 1 to 40% by weight, preferably 3 to 25% by weight, based on the total weight of the modifier of the present invention).

Coloring pigments can be included when visual contrast is desired, and specifically include dyes such as crystal violet, safranin, brilliant blue, malachite green, and acidrhodamine B, as well as inorganic pigments and organic pigments. . These colorants are present in an amount of 0.0001 to 0.05% by weight based on the total weight of the correction agent according to the present invention.
, preferably in a range of 0.001 to 0.01% by weight.

The correcting agent of the present invention is particularly advantageously used when correcting and erasing the image area of a lithographic printing plate obtained by plate making from a PS plate having a positive photosensitive layer on a support. This will be explained in detail below.

Supports for PS plates are dimensionally stable plate-like materials, including those conventionally used as supports for printing plates.

It will be done. Such supports include paper, plastic (
For example, paper laminated with polyethylene, polypropylene, polystyrene, etc.), metal sheets such as aluminum plates (including aluminum alloys), zinc plates, copper plates, iron plates, composite metal plates (for example, chromium-coated iron plates), etc. plates, such as cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate,
Plastic films such as cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc., paper or plastic films laminated or vapor-deposited with metals such as those mentioned above, JP-B-1973 It includes a composite sheet in which an aluminum sheet is bonded to a polyethylene terephthalate film as described in Japanese Patent No. 18327.

The support of the ps plate 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 machine and printed under standard conditions. The surface of the support is preferably subjected to hydrophilic 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 an undercoat layer after these treatments are used. There is a method of applying it. In addition, in the case of a support having a metal surface such as aluminum, graining treatment such as brush polishing and electrolytic polishing, immersion treatment in an aqueous solution of sodium silicate, fluoridated zirconate, phosphate, etc. This includes plating, coating, anodizing, etc.

Among the above-mentioned supports, a plate having a grained or anodized aluminum surface, or a chromium-coated iron plate is preferable because it improves the adhesion of the photosensitive layer.

Anodizing baths include hydrochloric acid, nitric acid, chromic acid, boric acid,
Examples include aqueous solutions of various acids such as sulfuric acid, persulfuric acid, phosphoric acid, sulfamino acid, and oxalic acid. Preferred is phosphoric acid. An aluminum plate that has been grained and further anodized is more preferred. Brush polished,
Furthermore, anodized aluminum plates, or aluminum plates that have been subjected to brush polishing and electrolytic polishing and further anodized, have particularly favorable adhesion with the photosensitive layer, so the resulting PS plates have high printing durability ( The modifier of the present invention is particularly advantageous.Also, surface roughness is known as a method of expressing the hydrophilicity of a support, and this surface roughness is also a measure of the adhesion of the photosensitive layer. Therefore, the centerline average roughness Ra (μm) is preferably 0.40 or more, more preferably 0.50 or more and 0.80 or less. (
Measuring device: Beltmeter 1 Tracer RHT 3150e, manufactured by Pelten AG, West Germany) Conventionally known positive photosensitive compositions can be used for the positive photosensitive layer, but typical ones include 0-quinone diazides. preferably 0-
Examples include naphthoquinone diazide compounds. Among the 0-naphthoquinonediazide compounds, in particular o-naphthoquinonediazide sulfonic acid esters or O-naphthoquinonediazidecarboxylic acid esters of various hydroxy compounds, and 0-naphthoquinonediazide sulfonic acid amides or 0-naphthoquinonediazidecarboxylic acid esters of aromatic amine compounds. Acid amides are preferred. Preferred hydroxy compounds include condensation resins of phenols and carbonyl group-containing compounds. These phenols include phenol,
Examples of the carbonyl group-containing compound include formaldehyde, benzaldehyde, and acetone.

Preferred hydroxyl compounds include phenol-formaldehyde resin, cresol-formaldehyde resin, pyrogallol-acetone resin, and resorcinol-benzaldehyde resin.

Typical specific examples of 0-quinonediazide compounds include:
Ester of benzoquinone-(1,2)-diazide sulfonic acid or naphthoquinone-(1,2)-diazide sulfonic acid with phenol-formaldehyde resin or cresol-formaldehyde resin, as described in JP-A-56-1044. Esters of naphthoquinone-(1,2)-diazide-(2)-5-sulfonic acid tresorcin-benzaldehyde resin, U.S. Pat. No. 3,635,7
Naphthoquinone-(1,2
)-diazide sulfonic acid and pyrogallol acetone resin, naphthoquinone-(1,2)-diazide-(2°
)-5-Sulfonic Acid Tresorci/-Hirogaro Rua
An example is an ester with a 17-ton copolycondensate.

Other useful O-quinonediazide compounds include those obtained by esterifying o-naphthoquinonediazide sulfonyl chloride with a polyester having a hydroxyl group at the terminal described in JP-A-50-117503; 113305, a homopolymer of p-human 50-xystyrene or a copolymer with other copolymerizable monomers is esterified with 0-naphthoquinonediazide sulfonyl chloride, Japanese Patent Publication No. 113305- Ester of bisphenol formaldehyde resin and 0-quinonediazide sulfonic acid described in US Pat. No. 29922, US Pat. No. 3.8
59,099, a condensate of a copolymer of alkyl acrylate, acroyloxyalkyl cargenate, and hydroxyalkyl acrylate with 0-quinonediazide sulfonyl chloride, Japanese Patent Publication No. 4
9-17481, a reaction product of a copolymerization product of styrene and a phenol derivative and 0-quinonediazide sulfonic acid, U.S. Patent No. 3,759,71
Amides of copolymers of p-aminostyrene and other copolymerizable monomers with O-naphthoquinonediazide sulfonic acid or O-naphthoquinonediazidecarboxylic acid as described in Specification No. 1; Examples include esterified products of hydroxypenzophenone and O-naphthoquinonediazide sulfonyl chloride.

Although these 0-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, specifically phenol formaldehyde resins,
Cresol formaldehyde resin, JP-A-55-578
Phenol/cresol formaldehyde copolycondensate resins such as those described in Japanese Patent No. 41 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 and formaldehyde are used. When used in combination with a condensate of
Even more preferred.

The content of the O-quinonediazide compound is preferably 5 to 80% by weight, 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, 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 0.
1~7g/n? is preferable, more preferably 0.5 to 4
g/m. 1.5g~4,! The modifier of the present invention becomes more effective at 9/m, and is most effective between 2.0 and 3-0.5'/rtl.

The PS plate thus obtained is exposed through a transparent original to a light source rich in actinic radiation, such as a carbon arc lamp, mercury lamp, metal halide 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 an alkaline agent.

As a developer for a positive type 28 plate, the molar ratio is [SiO2]/
(M) = 0.5~1.5 (Csho,), I
BM) are the molar concentration of SiO□, K, Na, and L, respectively.
(indicates the molar concentration of total alkali metals such as i) and generally contains 0.8 to 8% by weight of 5i02.

Methods for developing a PS plate image-exposed with the developer described above include a method of jetting the developer from a number of nozzles, a method of immersing the plate in the developer, a method of wiping with a sponge moistened with the developer, etc. Various methods known in the art are possible.゛As above (,
If a lithographic printing plate obtained by subjecting a PS plate to image exposure and development has an unnecessary image area, the image area is erased by applying the correcting agent of the present invention on the image area.

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.

After the lithographic printing plate from which unnecessary image areas have been erased is subjected to the usual processing steps such as development inking and/or gumming, or after finishing the development inking and/or gumming treatment after burning, Provided for printing. The correcting agent of the present invention is advantageously used because it does not cause deterioration in insensitivity due to burning of erased marks.

The correcting agent of the present invention can quickly erase unnecessary image areas and has extremely little adverse effect on adjacent images, improving the efficiency of plate-making work.

Furthermore, since the correcting agent of the present invention does not reduce its insensitivity even after burning the erased marks, failures caused by plate making and troubles during printing can be eliminated, and the efficiency of plate making and printing is improved.

The present invention will be specifically described below 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 0.3 + iz was electrochemically roughened in a nitric acid solution, washed, and then anodized in a sulfuric acid solution to form an oxide film of 2.511 parts m on the aluminum plate. formed on the surface.

After washing with water and drying, 3 parts of the esterified product of resorcin benzaldehyde resin and naphthoquinone 1,2-diazide-5-sulbonyl chloride synthesized according to the example of JP-A-56-1044, 9 parts of cresol-formalin novolac resin, and Victoria・Viea Blue BOH
(manufactured by Hodogaya Chemical Industry Co., Ltd.) A photosensitive solution prepared by dissolving 0.12 parts in 100 parts of 2-methoxyethanol was coated on the above support using a rotary coater and dried to form a 2.81 part m photosensitive layer. A positive PS version was obtained.

A halftone photographic transparent positive was placed on top of this, and from a distance of 0.8 m, the metal halide lamp used in Example 1 was used to
A printing plate was obtained by exposing for seconds and developing with an 11th developer.

(Developer) Potassium silicate A (SiO□26%, K, 013.5%) 120 parts 86
% potassium hydroxide 15.5 parts water
500
When unnecessary image areas were erased using the correcting agent of the present invention described below, they were completely erased in (9) seconds. When this printing plate was burned at 250°C for 8 minutes and then printed, all the erased traces were not smudged.Also, halftone dots that were 0.4ttrvt close to the erased area were smeared and had other negative effects. He didn't appear.

(Modifier of the present invention) Xylene 5 parts cyclohexanone 16 parts diethylene glycol dimethyl ether 7 parts r-butyrolactone
37 parts Hydroxypropyl methylcellulose 1.8 parts (4-% methoxy groups, 7-12% hydroxypropoxy groups, 2% at 20'C)
The viscosity of the aqueous solution is 4.8 to 7.2 cpm. ) 7' A/Cl Nick P-85 (manufactured by Asahi Denka Co., Ltd., oxyethylene oxypropylene block copolymer) 1.2
parts 85% phosphoric acid 2.1 parts 9
5% Acetic acid 2 parts Silicic acid fine powder 6.5 parts Water
1st part
Example 2 When the unnecessary image area of the printing plate obtained in the same manner as in Example 1 was erased using the following correcting agent of the present invention, it was completely erased in 15 seconds. This printing plate was burned in the same manner as in Example 1, and development ink was applied (92228 plate development ink 5PO-1, manufactured by Konishiroku Photo Industry Co., Ltd.). As a result, there were no traces of erasure in halftones or image areas. There was no staining, and the halftone dots close to the erased area did not stain up to about 0.2 mm.

(Modifier of the present invention) 16 parts of cyclohexanone, 11 parts of diethylene glycol dimethyl ether, 3 parts of γ-butyrolactone
7 parts changed to 30 parts.

Comparative Example 1 A correcting agent having the following composition similar to that described in JP-A-55-121447 (Example 4) was prepared, and the image area of the obtained printing plate was erased in the same manner as in Example 1. Burning and inking were performed in the same manner as 2.

It was found that the developing ink did not adhere to the halftone erased traces of the obtained printing plate, and that the insensitivity to oil decreased. In addition, it was found that the halftone dots close to the erased area were stained with developing ink up to the area 1.0 WWL away, which had a large adverse effect on the adjacent image.

(Known modifier) δ-valerolactone 29.5 parts Ethylene glycol dimethyl ether 30 parts Solvent naphtha (boiling point 140-200°C) 10 parts Hydroxypropyl methylcellulose 1.5 parts (same as Example 1) 7" Le O = Tsukuru 85 (same as used in Example 1) 10 parts 85% phosphoric acid 5 parts water
10 parts Silicic acid fine powder 5 parts Example 3 An aluminum plate with a thickness of 0.3 mm was electrochemically roughened in a hydrochloric acid solution, washed, anodized in a sulfuric acid solution, and sealed with hot water. , an oxide film of 2.7 g/lrl was formed on the surface.

After washing with water and drying, add 5 parts of esterified product of m-cresol formaldehyde resin and naphthoquinone-1,2-diazide-3-sulfonyl chloride and 1 part of cresol formalin novolak resin (phenol:cresol=2:8).
Part 0 and Victoria Pure Blue BOH0,14
2.8, j9 /rr?
A positive PS plate was obtained having a photosensitive layer of .

A halftone photographic transparency was placed on top of this, exposed and developed in the same manner as in Example 1 to obtain a printing plate. When unnecessary image areas of this printing plate were erased with the following correction agent of the present invention, 3
It was completely erased in 0 seconds.

When this printing plate was printed after burning at 260° C. for 7 minutes, there was no printing stain at all on the erased marks, including the halftones. Also, halftone dots near the erased area are 0
．． There were no adverse effects such as printing stains up to around 2 mtn.

(Modifier of the present invention) Xylene 4 parts Cyclohexanone 27 parts γ-butyrolactone 30 parts Diethylene glycol dimethyl ether 8 parts Silicic acid fine powder
7 parts Hydroxypropyl methyl cellulose 1 part Pluronic P -859 parts 85% phosphoric acid 2.1 parts Water

11 parts Example 4 When the unnecessary image area of the printing plate obtained in the same manner as in Example 3 was erased with the following correcting agent of the present invention, it was completely erased in 1 seconds. When this printing plate was burned in the same manner as in Example 3 and printed using a printing press, the erased marks, including the halftones, did not cause printing stains. Furthermore, there were no negative effects such as printing stains on halftone dots close to the erased area up to around 0.4 □.

(Modifier of the present invention) Xylene 5 parts Diethylene glycol dimethyl ether 10 parts r-butyrolactone 41 parts Dioxa 7
4-part cyclohexanone
8 parts hydroxypropyl methylcellulose
i, 8 parts Pluronic P-85 13 parts - Silicic acid fine powder 6 parts □'
99.5% acetic acid 2 parts 85
% phosphoric acid 2.6 parts water
1
0 parts pigment (food red No. 1) 0.002
Section Example 5 When the unnecessary image area of the printing plate obtained in the same manner as in Example 3 was erased using the following correcting agent of the present invention, it was completely erased in 40 seconds. When this printing plate was burned in the same manner as in Example 3 and printed using a printing press, the erased marks, including the halftones, did not cause printing stains. Furthermore, the halftone dot area that was 0.7iai close to the erased area had no adverse effects such as printing stains.

(Modifier of the present invention) Xylene 5 parts Diethylene glycol dimethyl ether 15 parts N,N-dimethylformamide 10 parts Cyclohexanone
22 parts γ-butyrolactone
21 parts hydroxyglobil methylcellulose t, s parts silicic acid fine powder
6.5 parts Pluronic P-85 13 parts 99.5% acetic acid 2 parts 85
% phosphoric acid 2.6 parts water
10
Colorant (Food Red No. 1) 0.002 parts Comparative Example 2 When the unnecessary image part of the printing plate obtained in the same manner as in Example 3 was erased with the following known correcting agent, it was erased by 60 parts.
Not only did it take several seconds, but when this printing plate was burned in the same manner as in Example 3 and printed on a printing press, printing ink adhered to the erased halftone areas and the printed matter was smeared.

From this, it can be seen that the correcting agent causes a decrease in the insensitivity when the erased traces are burned. It was also found that printing stains occurred in the halftone dot portions that were 0.7'1111 adjacent to the erased portions, which had a significant adverse effect on adjacent print lines.

(Known modifier) Xylene 5 parts N, N-
Dimethylformamide 15 parts Cyclohexanone 30 parts Diethylene glycol monomethyl ether 15 parts Hydroxyglobil methyl cellulose 1.8 parts Silicic acid fine powder
6.5 parts Pluronic P-8512 parts

Claims (1)

[Claims] A corrector for lithographic printing plates, comprising cyclohexanone and diethylene glycol dimethyl ether.