JP2555137B2 - Photosensitive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a photosensitive composition used for a photosensitive printing plate material that has been put into practical use in the fields of newspaper printing, form printing and the like.

B. Conventional Technology A printing plate material having a structure in which a photopolymerizable photosensitive resin layer is provided on a metal or plastic substrate has recently been put into practical use. These plate materials form an image on the substrate by causing photopolymerization in the photosensitive resin layer corresponding to the transparent portion and then eluting the unpolymerized portion into a suitable solvent.

As a typical example of the photosensitive resin composition for the above-mentioned use, a composition comprising an acrylic acid ester or a methacrylic acid ester, a water-soluble polymer and a photopolymerization initiator is known. As the molecule, polyvinyl alcohol resin is widely used.

C. Problem to be Solved by the Invention However, as a result of studies by the present inventors, there was a problem that a relatively long exposure time was required when the above water-soluble polymer was used.

D. Means for Solving the Problems However, as a result of the inventors of the present invention earnestly conducting research to solve the problems, a polyvinyl ester resin polymerized using a polymerization catalyst having a half-life at 60 ° C. of 200 minutes or less was obtained. When a composition comprising a polyvinyl alcohol-based resin having an average degree of polymerization of 1000 or less obtained by saponification, a polymerizable vinyl compound and a photopolymerization initiator is used as a photosensitive plate material, the exposure time is shortened and more excellent. The inventors have found new facts such as showing image reproducibility and completed the present invention.

Generally, the preparation and production of a photosensitive plate material using a polyvinyl alcohol resin is generally performed by dissolving the polyvinyl alcohol resin, the photosensitive monomer and other additives in water to form a viscous solution, coating it on a substrate and drying it. Be commercialized.

When the present inventor examined the cause of the poor performance of the conventional photosensitive plate material, a considerable amount of undecomposed catalyst remained inside the resin in the polyvinyl alcohol resin used for the conventional photosensitive plate material, During the manufacturing process of the photosensitive resin plate material, especially because of the partial polymerization of the photosensitive monomer due to the decomposition of the residual catalyst during drying, the resolving power such as reproducibility of fine lines and the washability during water development after exposure. Turned out to be a problem. As a result of investigating the cause of this, the polyvinyl alcohol-based resin obtained by using a polymerization catalyst having a half-life at 60 ° C of 200 minutes or less has substantially no undegraded catalyst. It was found that the produced photosensitive resin plate material gave excellent resolution and washability.

The polyvinyl alcohol-based resin of the present invention is not only a saponified homopolymer of vinyl ester, but also a formalized product, acetalized product, butyralized product, urethane compound, acetoacetic acid esterified product, sulfonic acid, carboxylic acid or the like thereof. Examples include esterification products.

Any vinyl ester capable of radical polymerization can be used as the vinyl ester. For example, vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate,
Examples thereof include vinyl laurate and vinyl stearate. Among them, vinyl acetate is the most polymerizable and is preferable.

Further, examples thereof include saponified copolymers of the vinyl ester and a monomer copolymerizable therewith, and as the monomer, ethylene, propylene, isobutylene, α-octene, α-
Olefins such as dodecene and α-octadecene, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, and itaconic acid, or salts or mono- or dialkyl esters thereof, acrylonitrile, methacrylonitrile, etc. Nitriles, amides such as acrylamide and methacrylamide, olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid or salts thereof, alkyl vinyl ethers, vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, etc. Is mentioned. However, it is not necessarily limited to this.

The polyvinyl alcohol resin used in the present invention must have an average degree of polymerization of 1,000 or less, preferably 800 or less. When the average degree of polymerization is 1000 or more, workability such as dissolution is deteriorated.

The average degree of saponification of the polyvinyl alcohol resin is 40 to 100 mol%, preferably 60 to 95 mol%.

The half-life at 60 ° C. used in the present invention is 20
Specific examples of the polymerization catalyst for 0 minutes or less include 2,2'-azobis- (2,4-dimethyl-4-methoxyvaleronitrile) and 2,2'-azobis- (2,4,4-trimethyl). Valeronitrile), 1,1'-azobis- (cyclooctane / carbonitrile), acetyl-cyclohexane / sulfonyl /
Peroxide, bis- (4-t-butylcyclohexyl) peroxy dicarbonate, bis- (2-ethylhexyl) peroxy dicarbonate, 2,2'-
Azobis (N, N'-dimethyleneisobutylamidine dihydrochloride, t-butylperoxyneodecanoate, isobutylperoxide, 2,4,4-trimethylpentylperoxyphenoxyacetate, di-3-methoxybutylperoxy Examples include dicarbonate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, di-n-butyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di-sec-butyl peroxydicarbonate.

In particular, 2,2'-azobis- whose half-life is less than 1 hour
(2,4-dimethyl-4-methoxy-valeronitrile),
2,2'-azobis- (2,4,4-trimethylvaleronitrile), 1,1'-azobis- (cyclooctanecarbonitrile) and the like are preferably used.

The polymerizable vinyl compound used in the present invention may be any compound as long as it can be polymerized by light, and has at least one ethylenically unsaturated bond. Examples of advantageous compounds include those having a hydroxyl group, an amide group, a polyalkylene glycol unit or the like in the molecule.

Particularly preferably, hydroxyalkyl (meth) acrylate, alkylene glycol di (meth) acrylate,
Polyalkylene glycol di (meth) acrylate, alkoxypolyalkylene glycol (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, (meth) allylamide, N-methylol Examples thereof include (meth) acrylamide, methylenebis (meth) acrylamide, hexamethylenebis (meth) acrylamide, divinylbenzene and the like, but are not necessarily limited thereto. As the photopolymerization initiator, any one can be used as long as it directly or indirectly generates a radical upon irradiation with light, benzoin,
Benzoin compounds, benzyl, benzyl compounds, polynuclear quinones and the like are put to practical use.

Specific polyvinyl alcohol-based resin (a) of the present invention,
The photosensitive composition containing the polymerizable vinyl compound (b) and the photopolymerization initiator (c) as a photosensitive component is (b) 30 to 250 parts by weight, (c) 0.01 to 15 parts by weight per 100 parts by weight. Although it is preferably used in the range of parts, (a), (b),
Components other than (c) such as ordinary polyvinyl alcohol-based polymers and polyamide-based polymers may be used within the range not impairing the purpose of the present invention.

In addition, known auxiliary agents such as thermal polymerization inhibitors and sensitizers may be used in combination, if necessary.

In order to produce a photosensitive composition from such components, each component is mixed in an aqueous medium using a homomixer and allowed to stand in the dark overnight, and then a filter cloth is attached and the by-product gel-like substance is filtered off. good.

In order to form an image by light irradiation using the composition of the present invention, first, the composition is applied to a substrate and dried, or a film is prepared from the composition in advance by an arbitrary method, and a film is prepared based on the film. Adhere to the material.

As the base material, plastic board, cotton, rayon, wool, woven fabric made of polyester-based / polyamide-based / polyacrylonitrile-based / polyvinyl alcohol-based synthetic fiber, non-woven fabric, gauze, zinc plate, aluminum plate, magnesium plate, steel plate, copper plate Etc. are used.

By using the polymer plate thus obtained and irradiating it with ultraviolet rays through a negative screen, the exposed areas become water-insoluble, and the unexposed areas can be dissolved in water. Only is removed. As the light source, a low pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a xenon lamp, etc. are used. If necessary, curing can be promoted by heating during exposure.

For the purpose of printing or the like, a non-woven fabric or a gauze is used as a base material and the image plate obtained by the above treatment is used as it is for dyeing to give a pattern to the fabric.

For the purpose of letterpress printing, intaglio printing, printed wiring, etc., the base material (metal) on which the image is formed is etched to corrode exposed metal portions.

In the present invention, a further excellent image plate can be obtained by further subjecting the image plate as described above to a hardening process.

E. Action and effect of the invention The half-life at 60 ° C of the present invention is an average polymerization degree of 1000 or less obtained by saponifying a polyvinyl ester resin polymerized using a polymerization catalyst having a polymerization catalyst of 200 minutes or less. If a photosensitive composition containing a resin is used,
Excellent resolution and excellent image reproducibility can be obtained.

Next, the composition of the present invention will be described in more detail with reference to Examples. In the examples, "parts" represent weight standards.

Example 1 and Comparative Example 1 2-2′-azobis (4-methoxy-2,4dimethyl)
The average degree of polymerization obtained by saponification by valeronitrile (half-life at 60 ° C: 12 minutes, 12 minutes) by a conventional method was 60.
0, 100 parts of polyvinyl alcohol having an average saponification degree of 88 mol% was added with 100 parts of desalted water and dissolved at 50 ° C., and then a solution prepared in advance to the following composition was added.

The mixture was thoroughly stirred to give a uniform viscous solution, which was filtered and degassed. The above composition was uniformly applied onto an aluminum plate and dried. The photopolymer plate thus obtained was saturated in a carbon dioxide gas stream, a negative film was brought into close contact with the photosensitive layer, exposed with a 3 KW high-pressure mercury lamp, and a mercury image was obtained to obtain a relief.

On the other hand, as Comparative Example 1, the same experiment as in Example 1 was carried out except that 2-2′-azobis-isobutyronitrile (60 ° C. half life 1900 minutes) was used as a polymerization catalyst.

In Example 1, as a result of examining the relief image obtained by completely removing the unexposed portion by development for 5 minutes, it was possible to completely reproduce very fine portions such as 3% halftone dots, 50 μ fine lines, and 200 μ independent points. I found out that

On the other hand, in Comparative Example 1, it was found that the unexposed portion could not be completely removed even after development for 6 minutes, and the fine line of 50 μm was distorted.

Example 2 2-2'-azobis-2,4 dimethylvaleronitrile (6
The same experiment as in Example 1 was conducted except that 0 ° C. half-life of 200 minutes) was used as the polymerization catalyst, and similar results were obtained.

Example 3 The same experiment as in Example 1 was conducted except that di-n-propylperoxydicarbonate (60 ° C. half life 44 minutes) was used as a polymerization catalyst, and similar results were obtained.

Example 4 The same experiment as in Example 1 was performed except that polyvinyl alcohol having an average degree of polymerization of 300 and an average degree of saponification of 80 mol% was obtained by the same procedure as in Example 1, and the same result was obtained.

Example 5 The same experiment as in Example 4 was performed except that the average saponification degree was replaced with 60 mol% in Example 4, and the same result was obtained.

Continuation of the front page (56) Reference JP-A-52-60702 (JP, A) JP-A-58-222102 (JP, A) JP-B 50-3041 (JP, B1) JP-B 46-14670 (JP) , B1) JP-B-52-39074 (JP, B1)

Claims (1)

(57) [Claims] 1. A polyvinyl alcohol resin having an average degree of polymerization of 1000 or less obtained by saponifying a polyvinyl ester resin polymerized with a polymerization catalyst having a half-life at 60 ° C. of 200 minutes or less, a polymerizable vinyl compound and photopolymerization. A photosensitive composition comprising an initiator.