JP2883353B2 - Photosensitive layer for printing plate - Google Patents

Description

The present invention relates to a photosensitive layer for a printing plate, and more particularly, to a photosensitive layer for a printing plate excellent in ink inking property and storage stability.

b. Conventional technology It has been conventionally known to apply a diazo photosensitive agent to a photosensitive layer for a lithographic printing plate. In particular, 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 that form the photosensitive layer of these photosensitive lithographic printing plates are diazo-based sensitizers, high-molecular polymers that can be mixed with them, and dyes, pigments, preservatives, and And a plasticizer and a surfactant for improving coating properties.

Among the materials for forming the photosensitive layer, those having a large effect on the characteristics of the photosensitive lithographic printing plate, such as image reproducibility, development stability, inking property, printing durability, and storage stability, are of high molecular weight. Often union.

As the polymer, generally, JP-A-50-118802,
JP-A-53-120903, JP-A-54-88403, JP-B-57-4
Various acrylic copolymers disclosed in Japanese Patent Application No. 3890 and Japanese Patent Application No. 63-151570 have been used. These copolymers are water-insoluble and have a hydroxyl group (-OH group) necessary for adhesion to an aluminum sheet, and a hydrophilic functional group such as a carboxylic acid group (-COOH group) that can be developed in a weak alkaline aqueous solution. Is an acrylic copolymer.

c. Problems to be Solved by the Invention However, because these acrylic copolymers are hygroscopic resins, photosensitive lithographic printing plates using this as a material for the photosensitive layer are coated after development during plate making. There is a drawback that the gum is lost by the desensitized gum to be used, and troubles such as poor ink deposition occur during printing.

In order to improve these drawbacks, a technique of mixing a lipophilic polymer compound in a photosensitive layer is known. For example, JP-A-55-527 and JP-A-63-204248 disclose techniques for adding a styrene-maleic anhydride copolymer or a substituted phenol-aldehyde condensation polymer.

However, it has been found that these methods have various disadvantages. For example, due to poor compatibility between the lipophilic polymer compound and the acrylic copolymer, coating unevenness occurs when coated on a support, or developability deteriorates when stored for a long time, This caused print stains.

The present inventors have conducted intensive studies to improve the above-mentioned drawbacks, and as a result, by mixing a specific copolymer in the photosensitive layer, the ink inking property is excellent and the developability does not change over a long period of time. It has been found that a photosensitive layer can be obtained, which has led to the present invention.

d. Means for Solving the Problems That is, the present invention provides stealyl acrylate and mono (2-methacryloxyethyl) hexa in a photosensitive layer containing an acrylic copolymer having a hydroxyl group and a carboxylic acid group and a diazo photosensitive agent. A photosensitive layer for a printing plate, characterized by mixing a copolymer containing hydrophthalate as a copolymer component; and a copolymer containing stearyl acrylate and mono (2-methacryloxyethyl) hexahydrophthalate as a copolymer component. An object of the present invention is to provide a photosensitive layer for a printing plate, characterized in that the above-mentioned photosensitive layer contains 5.0 to 30% by weight of the coalescence.

A copolymer containing stearyl acrylate and mono (2-methacryloxyethyl) hexahydrophthalate as a copolymer component (hereinafter, referred to as a mixed copolymer) belongs to a kind of acrylic copolymer and includes stearyl acrylate, In addition to a copolymer component such as (2-methacryloxyethyl) hexahydrophthalate, other components can be copolymerized. Other components can be arbitrarily selected as long as they are general unsaturated compounds. Among them, for example, 2-hydroxyethyl methacrylate, ethyl methacrylate, acrylonitrile and the like are preferable.

In the mixed copolymer, the content of stearyl acrylate is preferably from 10 to 90% by weight, more preferably from 20 to 80% by weight, based on the total amount of the copolymer. When the content is less than 10% by weight, the effect of improving the ink inking property cannot be obtained, and when it is more than 90% by weight, it becomes difficult to dissolve in an alkali developing solution. The content of mono (2-methacryloxyethyl) hexahydrophthalate is 10 to 90% by weight based on the total amount of the copolymer.
And more preferably 20 to 80% by weight. If it is less than 10% by weight, it is difficult to dissolve in an alkali developer, and if it is more than 90% by weight, the effect of improving the ink inking property cannot be obtained.
Gelation occurs depending on the reaction conditions.

It is desirable that the content of the mixed copolymer in the photosensitive layer for a printing plate of the present invention is from 5.0 to 30% by weight based on the total weight of the photosensitive layer. When the content is less than 5.0% by weight, gum is easily lost, and the effect of improving the ink adhesion is not obtained. When the content is more than 30% by weight, the printing durability is deteriorated.

The acrylic copolymer contained in the photosensitive layer of the present invention can be prepared by copolymerizing an addition polymerizable unsaturated compound having a hydroxyl group and an addition polymerizable unsaturated compound having a carboxylic acid group.

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

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, actyl, lauryl, dodecyl, cyclohexyl, tetrahydrofuryl, benzyl, stearyl, dimethylaminoethyl, diethylaminoethyl, chloroethyl, aryl (eg, phenyl, tolyl, naphthyl, etc.), glycidyls Acrylic esters or methacrylic esters, or nitrile acids such as acrylonitrile and methacrylonitrile are mentioned.

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 from 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, and when the content is more than 70% by weight, swelling of the image area at the time of development tends to occur. Further, the content of the addition polymerizable unsaturated compound having a carboxylic acid group is desirably 2.0 to 40% by weight, more preferably 3.0 to 30% by weight, based on the total amount of the acrylic copolymer. If it is less than 2.0% by weight, it will be difficult to dissolve in a weak 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 reaction conditions.

The acrylic copolymer is preferably contained in an amount of about 40 to 90% by weight based on the total weight of the photosensitive layer. If it is less than 40% by weight, the inking property and printing durability are inferior, and if it is more than 90% by weight, the developability deteriorates.

Examples of the diazo-based photosensitive agent added to the photosensitive layer of the present invention include conventionally known photosensitive agents such as diazo resins, P-quinonediazides, and diazo compounds (compounds having two or more diazo groups), and are particularly preferable. Is a diazo resin. Examples of the diazo resin include condensates of diazodiarylamine and an active carbonyl compound such as formaldehyde and acetaldehyde described in Japanese Patent Publication No. 40-8611, U.S. Pat. No. 2,922,715, and U.S. Pat. No. 2,946,683. Examples of the diazoarylamine include 4-
Diazodiphenylamine, 4-diazo-3-methyldiphenylamine, 4-diazo-3-methyldiphenylamine, 4-diazo-4-methoxydiphenylamine, 4-
Examples thereof include diazo-3-methoxydiphenylamine.

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. For example, benzenesulfonic acid, P-toluenesulfonic acid, 2,5-xylenesulfonic acid, linear or side chain type dodecylbenzenesulfonic acid (commonly known as dodecylbenzenesulfonic acid),
-Methoxy-4-hydroxy-5-benzoylbenzenesulfonic acid, methanyl yellow, 2-chlorotoluene-4
-Sulfonic acids, and their alkali metal salts, alkaline earth metal salts, ammonium salts and the like.

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, U.S. Pat. No. 4,093,465 and the like. Examples thereof include borofluoric acid, hexafluorophosphoric acid, 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 is preferably about 5 to 30% by weight based on the total weight of the photosensitive layer.

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. Commercially available such dyes include Victoria Pure Blue
BOH (made by Hodogaya Chemical Co., Ltd.), Oil Blue # 603
(Manufactured by Orient Chemical Co., Ltd.) and Permanent Blue # 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 4.0% by weight, more preferably 0.5 to 3.0% 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 can be added for the purpose of improving the coating property of the photosensitive layer and improving the inking property of the photosensitive layer. Examples of the plasticizer include 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, and diethyl phthalate. Isophthalate and the like can be mentioned.

The content of the above plasticizer is, based on the total weight of the photosensitive layer, 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 stearylate, sorbitan monostearate, sorbitan sex oleate, sorbitan monolaurate, polyoxyethylene nonylphenyl ether, polyoxyethylene octyl phenyl ether, and the like. it can.

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 two acrylic copolymers of the present invention, a diazo-based photosensitizer and, if necessary, a dye, a pigment, and a preservative,
Dissolve plasticizer, surfactant, etc. in one or a mixture of two or more of organic solvents such as methanol, methylene chloride, ethyl acetate, NN-dimethylformamide, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, etc. And various coating machines (for example, wheeler, roll coater, 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 in which two or more of these materials are combined can be used. Among them, an aluminum plate polished with a brush or a ball, an aluminum plate polished with a brush and then anodized, and anodized with an electrolytic polish. An aluminum plate which has been treated or a combination of these is suitable.

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

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 developer to obtain an image.

As a weak alkaline aqueous solution used as a developer,
For example, (1) a metal salt of a weak acid, for example, a metal salt such as a sodium salt, a lithium salt, and a potassium salt such as silicic acid, metasilicic acid, orthosilicic acid, phosphoric acid, pyrophosphoric acid, metaphosphoric acid, hexametaphosphoric acid, carbonic acid, tartaric acid, and boric acid Salt (2) Ammonia and its derivatives such as alkylamines (eg, monomethyl, dimethyl, trimethyl,
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.

In order to improve the dissolution rate of the unexposed portion of the photosensitive layer according to the invention, an activator and / or a solvent can be added to the above weakly alkaline aqueous solution. 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). Dodecylphenyl sulfate soda salt,
Sodium alkylnaphthalenesulfonate, sodium naphthalenesulfonate, formalin condensate of sodium naphthalenesulfonate), sodium dialkylsulfosuccinate,
Fatty acid amide sulfonate, alkyl phosphate ester,
Alkyl ether phosphates and the like 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. 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.

As the composition of the developer, the above weakly alkaline compound 0.1
~ 3.0% by weight, surfactant 0.5 ~ 2.0% by weight, solvent 0 ~ 2.0
Those containing by weight are preferred.

e. Action The mixed copolymer of the present invention is mixed with an acrylic copolymer having a hydroxyl group and a carboxylic acid group and a photosensitive layer containing a diazo-based photosensitizer, coated on a support, and dried. The used copolymer forms a layer on the surface of the photosensitive layer. In addition, since the layer of this copolymer has no hygroscopicity and strong oil sensitivity, it does not lose the gum due to the desensitized gum at the time of plate making, and has good ink inking property.

Further, since the layer of the copolymer is resistant to moisture and can be dissolved in an alkali developing solution, deterioration of the entire photosensitive layer due to moisture is prevented, and the developability of the photosensitive layer itself is not deteriorated.

Therefore, a photosensitive printing plate using the photosensitive layer for a printing plate of the present invention has no change in developability over a long period of time, has excellent ink deposition during printing, has no adverse effect on printing durability, and has a good No printed matter is obtained.

Furthermore, in the photosensitive layer of the present invention, the two types of copolymers used as a mixture are both compatible with each other because they belong to acrylic copolymers, and have good compatibility with each other. It has excellent film properties.

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 at 80 ° C. in which 3% of sodium hydroxide and 5% of sodium silicate were dissolved and polished with a brush, 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 is treated with an aqueous solution containing 5% of sodium silicate for 10 seconds,
An anodized aluminum plate was produced. A photosensitive solution having the following composition was 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 . .

The acrylic 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.

After completion of the dropwise addition, stirring was continued for 5 hours, 150 g of dioxane was added, and the mixture was poured into water to precipitate a 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.).

The copolymer (A) was obtained by polymerization with the following composition in the same manner as the acrylic copolymer (1).

A 20% by weight solution of this copolymer in 2-methoxyethanol was prepared, and its viscosity was measured to be 150 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.

The copolymer (B) was obtained by polymerizing with the following composition in the same manner as the acrylic copolymer (1).

A 20% by weight solution of this copolymer in 2-methoxyethanol was prepared, and its viscosity was measured to be 170 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.

The copolymer (C) was obtained by polymerizing with the following composition in the same manner as the acrylic copolymer (1).

A 20% by weight 2-methoxyethanol solution of this copolymer was prepared, and its viscosity was measured. As a result, it was 160 CPS (25 ° C.).

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.

The copolymer (D) was obtained by polymerizing with the following composition in the same manner as the acrylic copolymer (1).

A 20% by weight solution of this copolymer in 2-methoxyethanol was prepared, and its viscosity was measured. The result was 180 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.

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.

The photosensitive lithographic printing plates obtained in Examples 1 to 4 described above could be uniformly applied without any coating unevenness.

Negative films were vacuum adhered on the photosensitive layers of the various photosensitive lithographic printing plates obtained in Examples 1 to 4 and Comparative Examples 1 and 2, and were irradiated with ultraviolet rays at a distance of 1 m for 30 seconds using a 2 kW high-pressure mercury lamp. Then, using a developing solution having the following composition, immersion and development were performed at room temperature for 20 seconds, and after washing with water, a desensitizing gas solution (8-degree Arabic gum Baume solution) was applied thinly and dried to dry each lithographic printing plate. I got

Each of these plates is printed on a high-quality paper with an offset printing press (Heidelberg KOR type printing press) using a commercially available ink, and the number of prints from the start of printing until a print with sufficient ink density is obtained (the ) And press life. 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 deposition.

The various photosensitive lithographic printing plates obtained in Examples 1 to 4 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 the plates were made and proof-printed. ,
The number of days (preservability) at which the non-image area begins to cause background 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 has excellent storage stability.

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

Claims (2)

(57) [Claims] 1. A photosensitive layer containing an acrylic copolymer having a hydroxyl group and a carboxylic acid group and a diazo photosensitive agent contains stearyl acrylate and mono (2-methacryloxyethyl) hexahydrophthalate as copolymer components. A photosensitive layer for a printing plate, comprising a copolymer. 2. A photosensitive layer containing 5.0 to 30% by weight of a copolymer containing stearyl acrylate and mono (2-methacryloxyethyl) hexahydrophthalate as copolymer components.
The photosensitive layer for a printing plate according to claim 1, wherein the photosensitive layer is contained.