JP2832553B2 - Photosensitive layer for printing plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Industrial Field of the Invention The present invention relates to a photosensitive layer for a printing plate, and more particularly, it is excellent in ink inking property, printing durability and storage stability, and has improved developability. A photosensitive layer for a printing plate.

b. Prior art It has been conventionally known to apply a diazo-based photosensitizer to a negative-working photosensitive layer for a lithographic printing plate. Above all, in a photosensitive lithographic printing plate having a photosensitive layer formed on an aluminum thin plate, a diazo photosensitive agent is an indispensable element.

In recent years, many of the materials for forming the photosensitive layer of these photosensitive lithographic printing plates are diazo-based photosensitizers, high-molecular polymers that can be mixed with these, and dyes added as necessary.
It consists of pigments, preservatives, plasticizers for improving coatability, surfactants, and the like.

Among the materials that form these photosensitive layers, those that have a significant effect on the characteristics of the photosensitive lithographic printing plate, such as image reproducibility, ink adhesion, printing durability, storage stability, and developability, are polymer weight. Often union.

As the polymer, generally, JP-A-50-118802,
Various acrylic copolymers disclosed in JP-A-53-120903 and JP-B-57-51656 are used in a negative-working photosensitive layer. These copolymers are water-insoluble and have a hydroxyl group (-OH group) necessary for adhesion to an aluminum sheet.
And an alkali-soluble acrylic copolymer having a hydrophilic functional group such as a carboxylic acid group (—COOH group) that can be developed in a weakly alkaline aqueous solution.

c. Problems to be Solved by the Invention However, these copolymers are either negative-working photosensitive lithographic printing plates (hereinafter referred to as negative-working PS plates), either because of a hygroscopic resin or using these as a material for a photosensitive layer. ) Has the disadvantage that the long-term preservability is not very good, and the desensitized gum applied after development at the time of plate-making causes the gum to lose, resulting in troubles such as poor ink deposition during printing.

Further, as a developer for these negative PS plates, JP-A No.
As described in JP-A-51-77401, JP-A-53-4202, JP-B-59-36256, etc., a composition containing an alkali agent, an organic solvent, a surfactant and water is generally used. Among these, the organic solvents have health problems in terms of toxicity and odor, and also have drawbacks in that waste liquids are subject to BOD regulations. Further, the surfactant has a problem that bubbles are generated during development or drainage. Therefore, it was not a very preferable developer composition.

On the other hand, a developer composition not containing an organic solvent or a surfactant is conventionally used as a positive photosensitive lithographic printing plate (hereinafter, referred to as a positive PS plate).
It is called a version. However, it is not possible to develop the negative PS plate as described above with this composition. there were.

In order to solve such problems, Japanese Patent Publication No. 57-43890 proposes to use a polymer compound mainly composed of a monomer having an aromatic hydroxyl group.
It was not satisfactory in terms of ionic deposition and printing durability.

The present inventor has conducted intensive studies to improve the above-mentioned drawbacks, and as a result, has excellent ink depositability and printing durability, has no change in developability over a long period of time, and has an alkaline agent, an organic solvent, and a surfactant. The present invention has found a photosensitive layer which can be developed with a developing solution consisting of an agent and water or a developing solution consisting only of an alkali agent and water.

d. Means for Solving the Problems The present invention relates to a copolymer containing N- (4-hydroxyphenyl) maleimide and mono (2-methacryloxyethyl) hexahydrophthalate as copolymer components, and a diazo photosensitive agent. The present invention provides a photosensitive layer for a printing plate, comprising:

The above-mentioned copolymer containing N- (4-hydroxyphenyl) maleimide and mono (2-methacryloxyethyl) hexahydrophthalate as copolymer components (hereinafter, referred to as a mixed copolymer of the present invention) is a kind. It belongs to an alkaline copolymer and is made by copolymerizing other monomers in addition to N- (4-hydroxyphenyl) maleimide and mono (2-methacryloxyethyl) hexahydrophthalate, which are essential as copolymer components. You can also.

As other monomers, for example, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 4-hydroxyphenyl methacrylamide,
Examples include methyl methacrylate, ethyl methacrylate, n-butyl acrylate, lauryl acrylate, stearyl acrylate, and acrylonitrile.

The content of N- (4-hydroxyphenyl) maleimide in the mixed copolymer of the present invention is preferably from 10 to 90% by weight, more preferably from 20 to 90% by weight, based on the total amount of the mixed copolymer.
~ 80% by weight. When the content is 10% by weight or more, the ink-injection property is deteriorated, and it is difficult to develop with a positive PS plate developer comprising an alkali agent and water. On the other hand, at 90% by weight or more, a negative PS comprising an alkali agent, an organic solvent, a surfactant and water.
It becomes difficult to develop with a plate developer.

The content of mono (2-methacryloxyethyl) hexahydrophthalate is based on the total amount of the mixed copolymer.
10-90% by weight is preferred, more preferably 20-80% by weight
It is. If it is less than 10% by weight, it will be difficult to dissolve in the negative PS plate developer. On the other hand, if the content is more than 90% by weight, the effect of improving the ink deposition property cannot be obtained, and further, gelation is caused by the reaction conditions, which is not preferable.

The mixed copolymer of the present invention is desirably mixed in a range of 20 to 90% by weight based on the total weight of the photosensitive layer for a printing plate of the present invention.

Examples of the diazo-based photosensitizer to be added to the photosensitive layer of the present invention include conventionally known negative-type photosensitizers such as diazo resins and diazo compounds (compounds having two or more diazo groups), and are particularly preferable. Those are diazo resins.

As diazo resins, Japanese Patent Publication No. 40-8611, U.S. Pat.
And condensates of diazodiarylamines with active carbonyl compounds such as formaldehyde and acetaldehyde described in US Pat.
Examples of the diazoarylamine include 4-diazodiphenylamine, 4-diazo-3-methyldiphenylamine, 4-diazo-3'-methyldiphenylamine,
4-diazo-4'-methoxyphenylamine, 4-diazo-3-methoxydiphenylamine and the like can be mentioned.

Most preferably, the diazo resin is used in the form of an organic salt or an inorganic salt. Examples of the compound which forms an organic salt by combining with the above diazo resin include compounds described in JP-B-40-2203, JP-B-41-6813, JP-B-47-1167 and the like. Benzenesulfonic acid, P-toluenesulfonic acid, 2,5-xylenesulfonic acid, linear or side chain type dodecylbenzenesulfonic acid (commonly known as dodecylbenzenesulfonic acid), 2-methoxy-4-hydroxy-
5-benzoylbenzenesulfonic acid, methanyl yellow,
Examples thereof include 2-chlorotoluene-4-sulfonic acid, and alkali metal salts, alkaline earth metal salts, and ammonium salts thereof.

Examples of the compound which forms an inorganic salt by combining with the above diazo resin include JP-B-40-2203 and JP-A-54-9861.
No. 3, there are compounds described in U.S. Pat.No. 4,093,465, specifically, borofluoric acid, hexafluorophosphoric acid,
Examples thereof include phosphotungstic acid, thiocyanic acid, and alkali metal salts and ammonium salts thereof.

The diazo-based photosensitizers can be used alone or in combination, and the content thereof is preferably about 5 to 30% by weight based on the total weight of the photosensitive layer of the present invention.

Other lipophilic polymer or copolymer may be added to the photosensitive layer of the present invention. Examples thereof include phenolic resins, substituted phenolic resins, polyhydroxystyrenes, halogenated polyhydroxystyrenes, copolymers of hydroxystyrene and acrylic compounds, styrene-
Examples thereof include a maleic anhydride copolymer, an acrylic resin, and a modified acrylic copolymer.

Among these, an acrylic copolymer having a hydroxyl group and a carboxylic acid group (hereinafter, simply referred to as an acrylic copolymer) is preferable. This acrylic copolymer can be produced by copolymerizing an addition-polymerizable unsaturated compound having hydroxylation and an addition-polymerizable unsaturated compound having a carboxylic acid group.

Examples of the addition-polymerizable unsaturated compound having a hydroxyl group include: (1) acrylate and methacrylate having a hydroxyl group; for example, 2-hydroxyethyl or 2-hydroxypropyl acrylate, hydroxydodecyl, ethylene glycol, diethylene glycol, propylene glycol, and butylene glycol , Dipropylene glycol, polyethylene glycol, polypropylene glycol, trimethylolpropanepentaerythritol, 2-hydroxy-3-phenoxypropyl, 2-hydroxy-3
Acrylates and methacrylates such as methylphenoxypropyl; (2) acrylates and methacrylates of oligoesters having hydroxyl groups; for example, polyester diols of succinic acid and propylene glycol, polyesteridiols of maleic acid and propylene glycol, phthalic acid and propylene Acrylates such as polyester diols with glycols, polyester diols with hexahydrophthalic acid and propylene glycol, polyester diols with tetrahydrophthalic acid and propylene glycol, polyester diols with tetrahydrophthalic acid and propylene glycol and glycerin-1-butyl ether; Methacrylates, (3) acrylamide and methacrylamide having a hydroxyl group or derivatives thereof; Examples If, hydroxyethyl, hydroxyphenyl, hydroxynaphthyl, acrylamide or methacrylamide such as N- hydroxyethyl -N- methyl, and the like.

Examples of the addition-polymerizable unsaturated compound having a carboxylic acid group include acrylic acid, methacrylic acid, mono (2-methacryloxyethyl) hexahydrophthalate, and mono (2
-Acryloxyethyl) hexahydrophthalate and the like.

The above acrylic copolymer may further be copolymerized with another addition-polymerizable unsaturated compound. As the other addition-polymerizable unsaturated compound, a general unsaturated compound can be arbitrarily used, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl,
n-amyl, n-hexyl, 2-ethylhexyl, octyl, lauryl, dodecyl, cyclohexyl, tetrahydrofuryl, benzyl, stearyl, dimethylaminoethyl, diethylaminoethyl, chloroethyl, aryl (eg, phenyl, tolyl, naphthyl, etc.), glycidyls Acrylic esters or methacrylic esters, and nitriles such as acrylonitrile and methacrylonitrile are included.

In the acrylic copolymer, the content of the addition-polymerizable unsaturated compound having a hydroxyl group is preferably from 10 to 70% by weight, more preferably 20 to 70% by weight based on the total amount of the acrylic copolymer.
~ 60% by weight. When the content is less than 10% by weight, the adhesion to the aluminum support is deteriorated.

The content of the addition polymerizable unsaturated compound having a carboxylic acid group is 2.0 to 40 with respect to the total amount of the acrylic copolymer.
% By weight, more preferably 3.0 to 30% by weight. If it is less than 2.0% by weight, it will be difficult to dissolve in a weakly alkaline aqueous solution and the developability will be poor. On the other hand, if it is 40% by weight or more, gelation occurs depending on the reaction conditions.

The other lipophilic polymer such as the acrylic copolymer is preferably contained in an amount of about 0 to 50% by weight based on the total weight of the photosensitive layer. If the content is 50% by weight or more, the ink deposition property and the preservability become inferior, and it becomes difficult to develop with a positive PS plate developer comprising an alkali agent and water.

A dye or pigment can be added to the photosensitive layer of the present invention for coloring. As these dyes or pigments, dyes or pigments which are not eluted by the developing solution from the image portion (cured portion by irradiation with ultraviolet rays or the like) during development of the photosensitive layer are desirable.

Examples of the dye include crystal violet, malachide green, Victoria blue, methylene blue, ethyl violet, rhodamine B, and the like, and basic oily dyes that are derivatives thereof. Victoria Pure Blue is commercially available as such a dye.
BOH (made by Hodogaya Chemical Industry Co., Ltd.), oil blue ¥ 603
(Manufactured by Orient Chemical Co., Ltd.) and Permanent Blue No. 47 (manufactured by Daido Chemical Co., Ltd.).

Examples of the pigment include phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone red, and indanthrene blue. Commercially available products include Neozapon Blue FLE (produced by Birdish Aniline Co., Ltd.), Oil Blue BOS (produced by Orient Chemical Co., Ltd.), and Spiron Blue GNH (produced by Hodogaya Chemical Co., Ltd.). is there.

The content of the dye is about 0.1 to the total weight of the photosensitive layer.
To 5.0% by weight, more preferably 0.5 to 4.0% by weight. The content of the pigment is about 1.0 to 5.0% by weight, more preferably 2.0 to 4.0% by weight based on the total weight of the photosensitive layer.
% By weight.

Further, a preservative may be added to the photosensitive layer of the present invention. As a preservative, for example, citric acid, tartaric acid, lactic acid, 5-sulfosalicylic acid, oxalic acid, DL-malic acid,
2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid and the like. The content of these preservatives is about 0.1 to 4.0% by weight, more preferably 0.5 to 3.0% by weight, based on the total weight in the photosensitive layer.

Furthermore, a plasticizer or a surfactant may be added for the purpose of improving the coating property of the photosensitive layer or improving the ink deposition property of the photosensitive layer. As the plasticizer, for example, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, di-n-octyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, diisononyl phthalate, ethyl phthalyl ethyl glycol, dimethyl Isophthalate and the like can be mentioned.

The content of the defoaming agent is about
0.5 to 3.0% by weight, more preferably 0.6 to 2.0% by weight
It is.

Examples of the surfactant include sorbitan monooleate, sorbitan stearate, sorbitan monostearate, sorbitan sesquioleate, sorbitan monolaurate, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether and the like.

The content of the surfactant is about 0.4 to 2.0% by weight, more preferably 0.6 to 1.6% by weight based on the total weight of the photosensitive layer.
% By weight.

When the photosensitive layer of the present invention is formed on a support, the mixed copolymer of the present invention, a diazo-based photosensitizer and other polymers, dyes and pigments to be added as required, a preservative, a plasticizer, an interface An activator or the like is added to an organic solvent such as methanol, methylene chloride, ethyl acetate, tetrahydrofuran, N-
N-dimethylformamide, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether or the like is dissolved in one or a mixture of two or more solvents, and various coating machines (for example, a wheeler, a roll coater, a bar coater,
Using an extrusion coater)
dry.

As the support, paper, plastic film, or a metal plate such as copper, zinc, aluminum, and stainless steel;
Further, a composite material obtained by combining two or more of these can be used. Among them, an aluminum plate which has been brush- or ball-polished, an aluminum plate which has been brush-polished and then anodized, and anodized after electrolytic polishing An aluminum plate subjected to a treatment or a combination of these treatments is suitable.

The aluminum plate subjected to such a pre-treatment, further alkali conversion treatment with alkali silicate, zirconium fluoride, alkyl titanate, trihydroxybenzoic acid,
After boehmite treatment or coating treatment with an aqueous solution of strontium acetate, zinc acetate, magnesium acetate, calcium benzoate, etc., coating treatment with polyvinyl pyrrolidone, polyamine sulfonic acid, polyacrylic acid, polymethacrylic acid, poly-2-hydroxyethyl acrylate, etc. It can be performed as a process.

The photosensitive layer of the present invention coated on the support is exposed to actinic rays such as ultraviolet rays, and is developed using a weakly alkaline aqueous solution as a developing solution, so that unexposed portions are removed and the exposed portions are obtained as images. Can be

As a weak alkaline aqueous solution used as a developer,
For example, (1) metal salts of weak acids; for example, silicic acid, metasilicic acid, orthosilicic acid, phosphoric acid,
Metal salts such as sodium salt, lithium salt and potassium salt such as pyrophosphoric acid, metaphosphoric acid, hexametaphosphoric acid, carbonic acid, tartaric acid and boric acid; (2) ammonium and its derivatives; An aqueous solution of an alkaline compound such as an amine compound such as monoethyl, diethyl, or triethyl) or an alkanolamine (for example, monoethanolamine, diethanolamine, triethanolamine, or diisopropanolamine) can be used.

An activator and / or a solvent may be added to the above weak alkaline aqueous solution. As the activator, an anionic surfactant or an amphoteric surfactant can be used.

Examples of the anionic surfactant include those having 8 to 22 carbon atoms.
Alcohol sulfates (eg, polyoxyethylene alkyl sulfate soda salt), alkylaryl sulfonates (eg, sodium dodecylbenzene sulfonate, polyoxyethylene dodecylphenyl sulfate soda salt, sodium alkylnaphthalene sulfonate)
Sodium naphthalene sulfonate, formalin condensate of sodium naphthalene sulfonate), sodium dialkyl sulfosuccinate, fatty acid amide sulfonate, alkyl phosphate, alkyl ether phosphate and the like can be used.

As the amphoteric surfactant, for example, an alkyl betaine type or an alkyl imidazoline type surfactant is preferable.

As the solvent, alcohols and ethers are preferable, but a solvent that does not dissolve in water (20 ° C.) by 10% or more is most preferable. Examples of such a solvent include benzyl alcohol and DL-α-phenylethyl alcohol as alcohols. There are 2-phenylethyl alcohol and the like, and examples of the ethers include phenyl cellosolve and propylene glycol monobutyl ether.

The photosensitive layer of the present invention can also be used as a resist for fine processing or a photosensitive layer for image formation.

e. Action containing the mixed copolymer of the present invention and a diazo photosensitizer,
The photosensitive lithographic printing plate obtained by coating the photosensitive layer of the present invention on a support and drying it is extremely excellent in ink inking property and excellent in printing durability. This is presumably because the photosensitive layer of the present invention has less hygroscopicity and higher oil sensitivity than the conventional photosensitive layer, and thus does not lose the gum due to the desensitized gum during plate making. Further, even when stored for a long period of time, there is no change in developability or ink deposition property, and a printed matter free of stains can be obtained.

Further, the photosensitive layer of the present invention can be developed with a developer for developing a positive-type photosensitive lithographic printing plate even though the photosensitive layer is originally a negative-working photosensitive layer. In the case of processing both the plate and the positive type lithographic photosensitive printing plate, there is no need to prepare a developing solution or two types of developing devices, and a photosensitive layer which is economical and advantageous in terms of work. is there.

f. Examples Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Example 1 An aluminum plate was washed with an aqueous solution of 80 ° C. in which caustic soda 3% and sodium silicate 5% were dissolved, brush-polished, and then anodized with a sulfuric acid electrolyte for 1 minute (current density 2 A).
/ dm ² , voltage 10V). Next, after washing with water, the film was treated with an aqueous solution containing 5% of sodium silicate for 10 seconds to produce an anodized aluminum plate. A photosensitive solution having the following composition is applied to this aluminum plate using a spin coater (wheeler), and then dried at 80 ° C. for 3 minutes to obtain a photosensitive lithographic printing plate having a film thickness of 1.7 g / m ^2. Was.

Photosensitive liquid composition Mixed copolymer (1) 3.0 g Diazo-based photosensitizer (1) (0.3 g of 4-diazodife 2-methoxy-4-hydroxy-5-benzoylbenzenesulfonate of condensate of nilamine and formaldehyde) Victoria Pure Blue BOH 0.1 g (manufactured by Hodogaya Chemical Industry Co., Ltd.) Tartaric acid 0.03 g ethylene glycol monomethyl ether 90 g NN-dimethylformamide 10 g The mixed copolymer (1) was produced as follows.

Under a nitrogen stream, 0.3 g of azobisisobutyronitrile was added to 150 g of dioxane, the mixture was heated to 80 to 85 ° C., and a mixture having the following composition was dropped into the mixture with stirring.

N- (4-hydroxyphenyl) maleimide 80 g Mono (2-methacryloxyethyl) hexahydrophthalate 20 g After dropping, stirring was continued for 5 hours, 150 g of dioxane was added, and the mixture was poured into water to precipitate a copolymer. I let it. The precipitate was redissolved in 2-methoxyethanol, dropped into water, purified, and dried in vacuum (70 ° C.) to obtain a mixed copolymer (1).

A 2-methoxyethanol solution containing 20% by weight of this copolymer was prepared, and its viscosity was measured.
° C).

Example 2 A photosensitive lithographic printing plate was obtained in the same manner as in Example 1 except that a photosensitive solution having the following composition was used.

Mixed copolymer (1) 2.5 g Acrylic copolymer (A) 0.5 g Diazo-based photosensitizer (2) (0.3 g of 4-diazodiphen dodecylbenzenesulfonate of condensate of nilamine and formaldehyde) Oil Blue # 603 0.1 g (manufactured by Orient Chemical Industry Co., Ltd.) Citric acid 0.03 g Ethylene glycol monomethyl ether 90 g N-N-dimethylformamide 10 g The acrylic copolymer (A) is a mixed copolymer (1)
In the same manner as in the above, it was obtained by polymerization with the following composition.

2-hydroxy-3-phenoxypropyl acrylate 40 g methyl methacrylate 30 g acrylonitrile 10 g acrylic acid 20 g A 2-methoxyethanol solution containing 20% by weight of this acrylic copolymer was prepared, and the viscosity was measured.
It was 0 CPS (25 ° C).

Example 3 A photosensitive lithographic printing plate was obtained in the same manner as in Example 1 except that a photosensitive solution having the following composition was used.

Mixed copolymer (2) 3.0 g Diazo-based photosensitizer (3) (4-diazo-3-methoxide 0.3 g hexafluorinate of condensate of xidiphenylamine and formaldehyde) Oil blue 603 0.1 g DL- Malic acid 0.03 g Ethylene glycol monomethyl ether 90 g N-N-dimethylformamide 10 g The above mixed copolymer (2) was obtained by polymerization with the following composition in the same manner as in the mixed copolymer (1).

N- (4-hydroxyphenyl) maleimide 30 g mono (2-methacryloxyethyl) hexahydrophthalate 20 g 2-hydroxyethyl methacrylate 20 g acrylonitrile 20 g ethyl methacrylate 10 g 2-methoxyethanol containing 20% by weight of this mixed copolymer When the solution was prepared and the viscosity was measured, it was 270 CPS
(25 ° C.).

Comparative Example 1 A photosensitive lithographic printing plate was obtained in the same manner as in Example 1 except that a photosensitive solution having the following composition was used.

Acrylic copolymer (B) 3.0 g Diazo photosensitizer (3) 0.3 g Victoria Pure Blue BOH 0.1 g Oxalic acid 0.03 g Ethylene glycol monomethyl ether 90 g N-N-dimethylformamide 10 g The acrylic copolymer (B) is , Mixed copolymer (1)
In the same manner as in the above, it was obtained by polymerization with the following composition.

2-hydroxyphenyl methacrylamide 22.5 g 2-hydroxyethyl methacrylate 32.5 g methyl methacrylate 10 g methacrylic acid 6 g A 2-methoxyethanol solution containing 20% by weight of the mixed copolymer was prepared, and the viscosity was measured. 250CPS
(25 ° C.).

Comparative Example 2 A photosensitive lithographic printing plate was obtained in the same manner as in Example 1, except that a photosensitive solution having the following composition was used.

Acrylic copolymer (A) 3.0 g Diazo-based photosensitizer (1) 0.3 g Victoria Pure Blue BOH 0.1 g Oxalic acid 0.03 g Ethylene glycol monomethyl ether 90 g N-N-dimethylformamide 10 g Examples 1-3 and Comparative Examples A negative film was vacuum-adhered on the photosensitive layers of the various photosensitive lithographic printing plates obtained in Examples 1 and 2, and irradiated with ultraviolet rays at a distance of 1 m for 30 seconds using a 2KW high-pressure mercury lamp, and then a developer having the following composition ( 1),
Using (2), the developability of each plate was observed (developer temperature: 25 ° C.). Table 1 shows the results.

Developer (1) (similar composition to positive PS plate developer) JIS No. 3 sodium silicate 25 g potassium hydroxide 15 g water 1 kg Developer (2) (similar composition to negative PS plate developer) Potassium silicate 20% aqueous solution 50g Phenyl glycol PGH (organic solvent) 40g Potassium isopropyl naphthalenedisulfonic acid (surfactant) 5g Potassium sulfite 2g Water 903g As is clear from the results in Table 1, the lithographic printing plates of Examples 1 to 3 were positive-working printing plates while being negative-working printing plates.
It has the advantage that it can be developed even with a developer for developing PS plates.

Next, each plate prepared in Examples 1 to 3 and Comparative Examples 1 and 2 was exposed to light and developed with a developer (2). After washing with water, a desensitized gum solution (gum arabic solution at 8 degrees Baume solution) was thinly applied and dried to obtain each lithographic printing plate.

Each of these plates is printed on a high-quality paper with a commercially available ink using an offset printing machine (KOR type printing machine manufactured by Heidelberg Co.), and the number of prints from the start of printing until a printed matter having a sufficient ink density is obtained (ink deposition) And the printing durability. Table 2 shows the results.

From the results in Table 2, the lithographic printing plates of Examples 1 to 3 are:
It turns out that it is especially excellent in the ink inking property.

The various photosensitive lithographic printing plates obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were left in a high-humidity atmosphere at a temperature of 30 ° C. and a humidity of 80% for several days, after which plate making and proof printing were performed. ,
The number of days (preservability) at which the non-image area begins to cause background soiling was examined. Table 3 shows the results.

From the results shown in Table 3, it is understood that the photosensitive lithographic printing plates of Examples 1 to 3 have excellent storage stability.

f. Effects of the Invention According to the present invention, it is possible to obtain a negative-working photosensitive layer for a printing plate that is excellent in ink inking property, printing durability and storage stability, and can be developed even with a developer for a positive PS plate. Can be.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03F 7/032 G03F 7/021

Claims (1)

(57) [Claims] 1. A copolymer containing N- (4-hydroxyphenyl) maleimide and mono (2-methacryloxyethyl) hexahydrophthalate as copolymer components, and a diazo photosensitive agent. Photosensitive layer for printing plate.