JP2651929B2 - Photosensitive layer for printing plate - Google Patents

Description

The present invention relates to a novel photosensitive layer for a printing plate,
In particular, the present invention relates to a photosensitive layer for a lithographic printing plate which is excellent in ink deposition property and storage stability and has good printing durability.

b. Conventional technology It has been conventionally known to apply a diazo photosensitive agent to a photosensitive layer for a lithographic printing plate. Above all, a printing plate having a photosensitive layer formed on an aluminum thin plate (hereinafter referred to as a photosensitive lithographic printing plate) is an indispensable element of a diazo-based photosensitive agent. However, in recent years, many of the materials for forming the photosensitive layer of these photosensitive lithographic printing plates are:
It is composed of a diazo-based photosensitizer, a polymer mixed with the photosensitizer, and dyes and pigments added as needed. Among these materials, the characteristics such as image reproducibility, development stability, inking property, printing durability, and storage stability of a photosensitive lithographic printing plate often depend on a high molecular weight polymer.

Japanese Patent Application Laid-Open No. 50-118802 discloses this type of polymer.
No., JP-A-53-120903, JP-A-54-88403, Japanese Patent Publication No. 5
Various acrylic copolymers such as those described in JP-A-7-43890 have been used. These copolymers are water-insoluble and have a hydroxyl group (-OH) necessary for adhesion to an aluminum sheet, and a carboxylic acid group (-CO) which can be developed in a weak alkaline aqueous solution.
An acrylic copolymer having a hydrophilic functional group such as an OH group.

c. Problems to be Solved by the Invention However, perhaps because these copolymers are hygroscopic resins, photosensitive lithographic printing plates using this as a material for the photosensitive layer are not sensitive to oil-sensitive ink ) And storage stability were not very good.

As a result of intensive studies, the present inventors have improved the above-mentioned drawbacks and have developed a photosensitive layer having excellent ink depositability and good storage stability.

d. Means for solving the problem, that is, the present invention [Wherein, R is hydrogen or an alkyl group having 1 to 2 carbon atoms] in the structural unit and includes a copolymer having a hydroxyl group, and the content of the compound represented by the general formula [I] is 3 to 40% by weight based on the total amount of the polymer, and 70 to 95% by weight of the copolymer containing the above general formula [I] as a structural unit and having a hydroxyl group, based on the total weight of the photosensitive layer for a printing plate. And (2) the photosensitive layer provided on the support contains the copolymer, a diazo-based photosensitizer, and, if necessary, a dye and a pigment. It is a photosensitive layer for a printing plate.

The copolymer of the present invention belongs to a kind of acrylic copolymer, and is a copolymer containing a compound having a hydroxyl group and the following compound [II] as polymerization components.

[Wherein R is hydrogen or an alkyl group having 1 to 2 carbon atoms] Examples of the compound of the formula [II] include mono (2-methacryloxyethyl) hexahydrophthalate and mono (2-
(Acryloxyethyl) hexahydrophthalate and the like.

Examples of the compound having a hydroxyl group capable of polymerizing with these compounds include (1) acrylate and methacrylate having a hydroxyl group, for example, 2-hydroxyethyl or 2-hydroxypropyl acrylate, hydroxydodecylethylene glycol, diethylene glycol, propylene glycol, butylene glycol, Dipropylene glycol, polyethylene glycol, polypropylene glycol, trimethylolpropanepentaerythritol, 2-
Hydroxy-3-phenoxypropyl, 2-hydroxy-
Acrylates and methacrylates such as 3-methylphenoxypropyl; (2) acrylates and methacrylates of oligoesters having a hydroxyl group, for example, polyester diols of succinic acid and propylene glycol, polyester diols of maleic acid and propylene glycol, phthalic acid and propylene Acrylates and methacrylates such as polyester diols with glycols, polyester diols with hexahydrophthalic acid and propylene glycol, polyester diols with tetrahydrophthalic acid and propylene glycol and glycerin-1-butyl ether, and (3) acrylamide and methacryl having a hydroxyl group Amides or derivatives thereof, such as hydroxyethyl, hydroxyphenyl, hydroxynaphthyl, N-hydroxye Le -N- acrylamide or methacrylamide such as methyl, and the like.

Other components can be copolymerized with the copolymer of the present invention. Such other components can be arbitrarily selected as long as they are general unsaturated compounds. Among them, 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.), acrylates or methacrylates of glycidyls, and nitriles such as acrylonitrile, methacrylonitrile.

In the copolymer of the present invention, the content of the compound represented by the general formula [II] is preferably 3 to 40% by weight based on the total amount of the copolymer. If it is less than 3% by weight, it is difficult to dissolve in a weakly alkaline aqueous solution, and the developability is deteriorated. Conversely, if it is 40% by weight or more, gelation occurs depending on the reaction conditions, which is not preferable. Therefore, it is more preferably in the range of 5 to 30% by weight.

The amount of the copolymer containing the above general formula [I] in the structural unit and having a hydroxyl group is preferably in the range of about 70 to 95% by weight based on the total weight in the photosensitive layer for a printing plate of the present invention. If it is less than 70% by weight, the inking property and printing durability will be poor, and if it is more than 95% by weight, the developability will be poor.

Examples of the photosensitive agent to be added to the photosensitive layer of the present invention include various known agents such as diazo resins, p-quinonediazides, diazo compounds (compounds having two or more diazo groups), and particularly preferred are It is a diazo resin. As diazo resins, Japanese Patent Publication No. 40-8611, U.S. Pat.
And diazodiarylamines described in US Pat. No. 2,946,683 and the like and active carbonyl compounds such as formaldehyde and acetaldehyde. Examples of the diazoarylamine include 4-diazodiphenylamine, 4-diazo-3-methyldiphenylamine, 4-diazo-3'-methyldiphenylamine, 4-diazo-4'-methoxydiphenylamine, and 4-diazo-3-methoxydiphenylamine. Can be mentioned.

Most preferably, the diazo resin is used as an organic salt or an inorganic salt. Compounds which form organic salts by combining with the above diazo resins are disclosed in JP-B-40-2203 and JP-B-41-6813.
And JP-B-47-1167. For example, 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-benzoylbenzene Examples thereof include sulfonic acid, methanyl yellow, 2-chlorotoluene-4-sulfonic acid, and alkali metal salts, alkaline earth metal salts, and ammonium salts thereof. Further, as a compound that forms an inorganic salt by combining with the diazo resin,
JP-B-40-2203, JP-A-54-98613, U.S. Pat.
No. 65 and the like. Examples thereof include borofluoric acid, hexafluorophosphoric acid, phosphotungstic acid, thiocyanic acid, and alkali metal salts and ammonium salts thereof.

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

A dye or pigment may be added to the photosensitive layer for a printing plate of the present invention for the purpose of coloring. These dyes or pigments are
A dye or pigment which is not eluted by the developing solution from the image portion (cured portion by irradiation of ultraviolet rays or the like) during development of the photosensitive layer is desirable.

Examples of the dye include crystal violet, malachide green, Victoria blue, methylene blue, ethylene violet, rhodamine B, and the like, and basic oily dyes which are derivatives thereof. Commercially available Victoria Pure Blue BOH (Hodogaya Chemical Industry Co., Ltd.)
Oil Blue # 603 (Orient Chemical Industry Co., Ltd.)
Permanent Blue # 47 (Daido Chemical Co., Ltd.)
Manufactured).

Examples of the pigment include phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone red, and indanthrene blue. Neozapon Blue FLE (manufactured by Purdish Aniline Co., Ltd.), Oil Blue BOS (manufactured by Orient Chemical Industry Co., Ltd.), and Spin Blue GNH (Hodogaya Chemical Industry Co., Ltd.)
Manufactured).

The content of the dye is about 0.1 to 4.0% by weight, more preferably 0.1 to 4.0% by weight, based on the total weight of the photosensitive layer for a printing plate of the present invention.
It is in the range of 5 to 3.0% by weight. The content of the pigment is about 0.1 to 5.0% by weight, more preferably 2.0 to 4.0% by weight, based on the total weight of the photosensitive layer for a printing plate of the present invention.

When the photosensitive layer for a printing plate of the present invention is formed on a support, the acrylic copolymer of the present invention, a diazo-based photosensitizer and, if necessary, a dye or pigment organic solvent such as methanol,
It is dissolved in one or more mixed solvents such as methylene chloride, ethyl acetate, N-N-dimethylformamide, ethylene glycol monomethyl ether, ethiglycol monoethyl ether, etc., and various coating machines (for example, a whiter, a roll coater, a bar coater, Using an extrusion coater or the like, and dried.

As the support, paper, plastic film, or a metal plate such as copper, zinc, aluminum, or stainless steel, or a composite material obtained by combining two or more of these can be used. An aluminum plate, an aluminum plate which has been subjected to anodizing treatment after brush polishing, an aluminum plate which has been subjected to electrolytic polishing and then anodized, or an aluminum plate which has been subjected to a treatment in which these are combined are suitable.

The aluminum plate thus treated is further treated with alkali silicate, zirconium fluoride, alkyl titanate,
Chemical conversion treatment with trihydroxybenzoic acid, etc., boehmite treatment, coating treatment with an aqueous solution of strontium acetate, zinc acetate, magnesium acetate, calcium benzoate, etc., coating with polyvinylpyrrolidone, polyaminesulfonic acid, poly-2-hydroxyethyl acrylate, etc. The processing can be performed as a post-processing.

The photosensitive layer coated on the support is exposed to actinic rays such as ultraviolet rays and developed with a weakly alkaline aqueous solution to obtain an image.

Examples of the weak alkaline aqueous solution used as the developer include (1) a metal salt of a weak acid such as silicic acid, metasilicic acid, orthosilicic acid, phosphoric acid, pyrophosphoric acid, metaphosphoric acid, hexametaphosphoric acid, carbonic acid, tartaric acid, boric acid, and the like. The sodium salt of
Metal salts such as lithium salts and potassium salts; (2) ammonia and its derivatives, for example, alkylamines (for example, amine compounds such as monomethyl, dimethyl, trimethyl, monoethyl, diethyl, and triethyl);
Alternatively, an aqueous solution of an alkaline compound such as an alkanolamine (for example, monoethanolamine, diethanolamine, triethanolamine, diisopropanolamine) can be used.

An activator and / or a solvent can be added to the above alkaline aqueous solution in order to improve the dissolution rate of the unexposed portion of the photosensitive layer. Examples of the activator include anionic surfactants such as sulfates of alcohols having 8 to 22 carbon atoms (eg, polyoxyethylene alkyl sulfate soda salt) and alkylaryl sulfonates (eg, sodium dodecylbenzene sulfonate, polyoxyethylene). Dodecyl phenyl sulfate sodium salt, sodium alkyl naphthalene sulfonate, sodium naphthalene sulfonate, formalin condensate of sodium naphthalene sulfonate), sodium dialkyl sulfosuccinate, fatty acid amide sulfonate, alkyl phosphate, alkyl ether phosphate, etc. Can be used.

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. As such a solvent, for example, benzyl alcohol, DL-α-phenylethyl alcohol, There are 2-phenylethyl alcohol and the like, and examples of the ethers include phenyl cellosolve, propylene glycol monobutyl ether and the like.

The composition of the developing solution is preferably in the range of 0.1 to 3.0% by weight of the alkaline compound, 0.5 to 2.0% by weight of the surfactant, and 0 to 2.0% by weight of the solvent.

The copolymer having the general formula [I] in the structural unit according to the present invention and having a hydroxyl group can also be used as a binder resin for other photosensitive materials, and is mixed with a photosensitive substance other than the diazo-based photosensitive agent as described above. To form a photosensitive layer.
Examples of the photosensitive substance other than the diazo-based photosensitive agent include a compound having a photosensitive azide compound, an o-quinonediazide compound, an ethylenically unsaturated compound, and causing a photoduplication reaction or a photopolymerization reaction. Further, it can be used as an image forming binder resin by electrophotography by mixing with a photoconductive substance.

e. Examples The present invention will be described according to the following examples.

Example 1 Aluminum plate was 3% sodium hydroxide and 5% sodium silicate
%, Dissolved in an aqueous solution of 80 ° C., brush-polished, and then anodized with a sulfuric acid electrolyte for 1 minute (current density
2A / dm ^2, voltage 10V). Next, after washing with water, the film was treated with a 5% aqueous solution of sodium metasilicate for 10 seconds to prepare an anodized aluminum plate. This aluminum plate is coated with a photosensitive solution having the following composition by a spin coater (Whylar)
And then dried at 80 ° C. for 3 minutes.
A photosensitive lithographic printing plate of 7 g / m ² was obtained.

Composition of photosensitive solution Copolymer (1) 3.0 g Diazo compound (1) (dodecylbenzene sulfonate of condensate of 4-diazodiphenylamine and formaldehyde) 0.3 g Oil blue # 603 (manufactured by Orient Chemical Industry Co., Ltd.) 0.1 g ethylene glycol monomethyl ether 90 g N-N-dimethylformamide 10 g The above 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.

2-hydroxy-3-phenoxypropyl acrylate 40 g methyl methacrylate 30 g acrylonitrile 10 g mono (2-methacryloxyethyl) hexahydrophthalate of the general formula [II] 20 g After completion of dropping, stirring was continued for 5 hours, and 150 g of dioxane was added. The copolymer was poured into water to precipitate the copolymer. The precipitate was redissolved in 2-methoxyethanol, dropped into water, purified, and dried in vacuum (70 ° C.) to obtain a copolymer (1).

A 20% by weight solution of this copolymer in 2-methoxyethanol was prepared, and its viscosity was measured to be 300 CPS (25 ° 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.

Copolymer (2) 3.0 g Diazo compound (2) (2-methoxy-4-hydroxy-5-benzoylbenzenesulfonate of condensate of 4-diazodiphenylamine and formaldehyde) 0.3 g Victoria Pure Blue BOH (Hodogaya) Industrial Co., Ltd. 0.1
g Ethylene glycol monomethyl ether 90 g N-N-dimethylformamide 10 g The copolymer (2) is a copolymer obtained by polymerizing with the following composition in the same manner as the copolymer (1), and is expressed in terms of weight ratio. 2-hydroxyethyl-3-phenoxypropyl acrylate / 2-hydroxyethyl methacrylate / methyl methacrylate / acrylonitrile / general formula / mono (2-methacryloxyethyl) hexahydrophthalate of [II] = 30/10/40/10 / 10 / composition.

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.

Copolymer (3) 3.0 g Diazo compound (3) (hexafluorophosphate of condensate of 4-diazo-3-methoxydiphenylamine and formaldehyde) 0.3 g Oil blue # 603 0.1 Ethylene glycol monomethyl ether 90 g N- N-dimethylformamide 10 g The copolymer (3) is a copolymer obtained by polymerizing with the following composition in the same manner as the copolymer (1), and is a polyester of phthalic acid and propylene glycol in a weight ratio. It is a composition of diol monoacrylate / 2-hydroxyethyl methacrylate / ethyl methacrylate / acrylonitrile / mono (2-methacryloxyethyl) hexahydrophthalate of general formula [II] = 20/20/37/10/13.

Example 4 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.

Copolymer (4) 3.0 g Diazo compound (1) 0.3 g Oil blue # 603 0.1 g Ethylene glycol monomethyl ether 90 g N-N-dimethylformamide 10 g The above copolymer (4) is the same as copolymer (1). A copolymer obtained by polymerization in the same manner as described below and having a weight ratio of N- (4-hydroxyphenyl) methacrylamide / 2-
Hydroxyethyl methacrylate / methyl methacrylate / mono (2-methacryloxyethyl) of general formula [II]
Hexahydrophthalate = 20/40/20/20.

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.

Copolymer (5) 3.0 g Diazo compound (1) 0.3 g Oil blue # 603 0.1 g Ethylene glycol monomethyl ether 90 g N-N-dimethylformamide 10 g The copolymer (5) was 2-hydroxy- by weight ratio. 3
A copolymer consisting of phenoxypropyl acrylate / methyl methacrylate / acrylonitrile / methacrylic acid = 50/35/10/5

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.

Copolymer (6) 3.0 g Diazo compound (2) 0.3 g Victoria Pure Blue BOH 0.1 g Ethylene glycol monomethyl ether 90 g N-N-dimethylformamide 10 g The above copolymer (6) is 2-hydroxy- by weight ratio. 3
Phenoxypropyl acrylate / 2-hydroxyethyl methacrylate / methyl methacrylate / acrylonitrile / methacrylic acid = 30/10/45/10/5 copolymer.

Comparative 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.

Copolymer (7) 3.0 g Diazo compound (3) 0.3 g Oil blue # 603 0.1 g Ethylene glycol monomethyl ether 90 g N-N-dimethylformamide 10 g The above copolymer (7) is phthalic acid and propylene in a weight ratio. Monoacrylate of polyesterol with glycol / 2-hydroxyethyl methacrylate / ethyl methacrylate / acrylonitrile / methacrylic acid = 20/20/45
It is a copolymer consisting of / 10/5.

Comparative Example 4 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.

Copolymer (8) 3.0 g Diazo compound (1) 0.3 g Oil blue # 603 0.1 g Ethylene glycol monomethyl ether 90 g N-N-dimethylformamide 10 g The copolymer (8) was N- (4 -Hydroxyphenyl) methacrylamide / 2-hydroxyethyl methacrylate / methyl methacrylate / methacrylic acid =
It is a copolymer consisting of 20/40/35/5.

Negative films were vacuum adhered on the photosensitive layers of the various photosensitive lithographic printing plates obtained from Examples 1 to 4 and Comparative Examples 1 to 4, and were irradiated with ultraviolet rays for 30 seconds at a distance of 1 m using a 2 kW high-pressure mercury lamp. Then, using a developer having the following composition, immersion is performed for 20 seconds at room temperature for development. After washing with water, a desensitized gum solution (8B
e) was thinly applied and dried to obtain each lithographic printing plate.

Developer composition Potassium silicate 20% aqueous solution 50 g Phenyl glycol PGH (Nippon Emulsifier Co., Ltd.) 40 g Isopropyl naphthalene disulfonic acid potassium 5 g Potassium zincate 2 g Water 903 g Offset printing of each of these plates (Heidelberg KOR type printing press) ), Printing was performed on high quality paper with a commercially available ink, and the printing durability was examined. Further, the number of sheets (the number of inlaid sheets) from the start of printing until a printed matter having a sufficient ink density was obtained was also examined at the same time. Table 1 shows the results.

From the results shown in Table 1, it can be seen that the lithographic printing plate according to the present invention is excellent in ink depositing property and has high printing durability.

Further, the photosensitive lithographic printing plates obtained from Examples 1 to 4 and Comparative Examples 1 to 4 were left in a high humidity atmosphere at a temperature of 30 ° C. and a humidity of 80% for several days. The number of days (preservability) at which the image area starts to cause soiling was examined. Table 2 shows the results.

From the results in Table 2, it can be seen that the photosensitive lithographic printing plate according to the present invention is excellent in storage stability.

f. Effects of the Invention According to the present invention, it is possible to obtain a photosensitive layer for a printing plate that is excellent in ink inking property, storage stability and printing durability.

Claims (2)

(57) [Claims] (1) A photosensitive layer provided on a support has the following general formula (I): [Wherein, R is hydrogen or an alkyl group having 1 to 2 carbon atoms] in the structural unit and includes a copolymer having a hydroxyl group, and the content of the compound represented by the general formula [I] is 3 to 40% by weight based on the total amount of the polymer;
The photosensitive layer for a printing plate, wherein the copolymer having the structural unit and having a hydroxyl group accounts for 70 to 95% by weight based on the total weight of the photosensitive layer for a printing plate. 2. The method according to claim 1, wherein the photosensitive layer provided on the support contains the copolymer, a diazo-based photosensitive agent, and, if necessary, a dye or a pigment. Photosensitive layer for printing plate.