JPS58127922A - Photosensitive resin composition - Google Patents

Abstract

PURPOSE:To obtain a water-developable material for a printing plate by using a photosensitive resin consisting of polyvinyl acetate with a specified saponification degree, a multifunctional monomer having >=2 (meth)acryloyl groups and OH groups by a number not exceeding the number of the (meth)acryloyl groups, and a specified compound having OH groups. CONSTITUTION:A photosensitive resin composition is prepared by adding a photosensitizer and a thermopolymn. inhibitor to 100pts.wt. partially saponified polyvinyl acetate (A) with 50-99mol% saponification degree, 10-300pts.wt. multifunctional monomer (B) having >=2 (meth)acryloyl groups and OH groups by a number not exceeding the number of the (meth)acryloyl groups in the same molecule, and 1-60pts.wt. satd. compound (C) having OH groups such as diethylene glycol. The mol.wt. of the component B is <=2,000 and the component B includes a multifunctional monomer represented by formulaI. The component C has <=1,000mol.wt. and >=150 deg.Cb.p. The composition is applied to a base film and photopolymerized to obtain a water-developable flexible printing plate with high resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel water-developable photosensitive resin composition, which is a partially saponified polyvinyl acetate-based resin composition that provides a printing plate material with high image reproducibility and flexibility. This invention relates to a photosensitive resin composition.

There are several known examples of systems in which partially saponified polyvinyl acetate is used as the main resin as a photosensitive resin composition that utilizes a photoinsolubilization reaction by photopolymerization and can be developed with neutral water. Known examples can be roughly divided into two types. The first system imparts photosensitivity to partially saponified polyvinyl acetate by blending a photopolymerizable monomer mainly consisting of a monofunctional (meth)acrylic acid ester having a hydroxyl group (Japanese Patent Publication No. 46 -19401°Special Publication Showa 5Q-3Q41.Special Publication Showa 52-275<51).

The second system imparts photopolymerizability by reacting a compound having an unsaturated group to the hydroxyl group of 9-partly saponified polyvinyl acetate (Japanese Patent Publication No. 4B-696).
2, Special Publication No. 49-59.25° No. 48-55282
．． %Opened in 1972-65292゜Unexamined in 1972-66151.
JP-A-50-30602° JP-A-50-45087. (Japanese Patent Application Laid-Open No. 54-13890).

Known examples of the first family include, for example, β-hydroxyethyl (meth)acrylate and β-hydroxypropyl (
The use of monofunctional (meth)acrylic acid esters having a hydroxyl group and one unsaturated group, such as meth)acrylate, as the main photopolymerizable monomer has been shown. These monofunctional ester monomers have very good compatibility with partially saponified polyvinyl acetate. Therefore, it plays a role in helping the compatibility of polyfunctional esters and benzoin alkyl ether photosensitizers that are poorly compatible with 9-partly saponified polyvinyl acetate. However, in order to obtain sufficient compatibility, a large amount of monofunctional (meth)acrylic acid ester having a hydroxyl group must be used. Therefore, in this case, the crosslinked structure formed by photopolymerization has low three-dimensionality because it is a polymer mainly composed of monofunctional acrylic acid ester.

As a result, for example, the water resistance of the photocured part becomes insufficient,
During development, a portion of the photocured portion often dissolves into water.

Therefore, it is difficult to apply it to printing plate materials that require a high degree of image reproducibility.

In order to modify this point, for example, JP-A-50-276
In 02, it is proposed to use polyfunctional unsaturated monomers having two or more unsaturated groups and even more hydroxyl groups in the same molecule.

Since this polyfunctional unsaturated monomer has three or more hydroxyl groups, it has good compatibility with partially saponified polyvinyl acetate, and the crosslinked structure formed by photopolymerization has a polyfunctional unsaturated monomer. Because it is used, it has a high density. However, this crosslinked structure has strong hydrophilic properties due to the excessive number of bonded hydroxyl groups, resulting in insufficient water resistance of the photocured area, making it unsuitable for applications that require a high degree of image reproducibility. Have difficulty. As mentioned above, in all known examples of imparting photosensitivity by blending photopolymerizable monomers into partially saponified polyvinyl acetate, the water resistance of the photocured portion is insufficient, resulting in high-quality images. It was difficult to put it into practical use for printing plate materials that require high reproducibility.

Regarding those that impart photosensitivity by introducing unsaturated groups of the second type into partially saponified polyvinyl acetate,
Special Publication Showa 48-6962. Japanese Patent Publication No. 48-6615. JP-A-5O-45O87 discloses a method in which maleic acid or a derivative thereof is reacted with the hydroxyl group of partially saponified polyvinyl acetate.
It introduces an unsaturated group, and 4! Kaisho 4
8-5528 is cinnamate ester, JP-A-48-652
92 reacts unsaturated lactone in the same way. However, in order to obtain sufficient image reproducibility as a printing plate material simply by introducing unsaturated groups into partially oxidized polyvinyl acetate, it is necessary to introduce a large amount of unsaturated groups. Sufficient photopolymerizability must be imparted to the saponified polyvinyl acetate polymer itself. To achieve this, a large amount of hydroxyl groups must be substituted to impart water solubility to the 9-partly saponified polyvinyl acetate, resulting in a significant decrease in water developability. In this way, attempts to impart photosensitivity to 9-partly saponified polyvinyl acetate simply by introducing an unsaturated group make it difficult to achieve both high image reproducibility and good water developability. In order to improve these drawbacks, Japanese Patent Publication No. 49-5923 was published.

It is proposed that N-methylolacrylamide be reacted with the hydroxyl groups of partially saponified polyvinyl acetate to introduce unsaturated groups, and that this polymer be blended with a photopolymerizable (meth)acrylate. Furthermore, in JP-A-54-1380190, an unsaturated group is introduced into partially saponified polyvinyl acetate by reacting an unsaturated aldehyde such as acrolein, and a photopolymerizable (meth)acrylate is blended into this. Proposed. However, in these cases, the unsaturated group introduced into the partially saponified polyvinyl acetate is (
1) Since it is not an acryloyl group, it has poor copolymerizability with the (meth)acryloyl group of the photopolymerizable monomer.

Therefore, the probability that the partially saponified polyvinyl acetate polymer participates in the crosslinking reaction formed by polymerization of the photopolymerizable monomer is low,9 and the expected improvement in image reproducibility is not observed.

As mentioned above, in the known example of using partially saponified polyvinyl acetate as the main resin and imparting photosensitivity using a photopolymerization reaction, fine lines such as 133 lines, 3% halftone dots, and 50μ fine lines are used. It has been difficult to put this into practical use in printing plate materials that require image reproduction.

The present inventors have intensively studied a partially saponified polyvinyl acetate photosensitive resin composition that has high image reproducibility and is developable with neutral water, and as a result, has arrived at the present invention described below.

That is, the present invention relates to a photosensitive resin composition characterized by comprising the following components A, B, and C.

A, Partially saponified polyvinyl acetate with a degree of saponification of 60 to 99 molar 100 parts by weight B0 Molecular weight 2000
Below, polyfunctional (meth)acrylates 10 to 3 have two (meth)acryloyl groups in the same molecule and simultaneously have a number of hydroxyl groups not exceeding the number of (meth)acryloyl groups.
00 parts by weight C1 1 to 60 parts by weight of a saturated compound having a molecular weight of 1000 or less and a boiling point of 150° C. or more and having a hydroxyl group in the molecule The present invention is characterized in that it consists of components A, B, and C as described above. This is a partially saponified polyvinyl acetate photosensitive resin composition that can be developed with neutral water and has excellent image reproducibility and printing plate flexibility.

Each component of the present invention will be explained in detail below.

The partially saponified polyvinyl acetate used as the raw material for component A has a degree of saponification of 60 to 99 mol. If the degree of saponification is less than 60 mol%, the water solubility will drop significantly and water development will become impossible, so the lower limit of the degree of saponification is 60 mol%. Further, completely saponified polyvinyl acetate having a degree of saponification of 100 molti cannot be used because it has poor solubility in room temperature water and poor compatibility with component B. Therefore, the upper limit of the degree of saponification is 99 mol. For the above reasons, it is necessary that the partially saponified polyvinyl acetate of component A has a degree of saponification of 60 to 99 molar ratios.

Regarding the molecular weight, any molecular weight can be used, but from the viewpoint of compatibility with component B, the degree of polymerization is 200 to 20.
00 is preferred. It is also possible to use two or more types of components with different degrees of saponification or polymerization as component A.

Component B has a molecular weight of 2000 or less, and is a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups and a number of hydroxyl groups not exceeding the number of (meth)acryloyl groups in the same molecule.

For example, the first order can be mentioned. However, it is not limited to this as long as it satisfies one condition. Glycerol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane di(meth)azilylate, bentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolethane di(meth)acrylate, Tetramethylolethane di(meth)
The epoxy groups of polyvalent glycidyl ethers such as acrylate, tetramethylolethane tri(meth)acrylate, and ethylene glycol diglycidyl ether (
Polyfunctional (meth)acrylates having two or more (meth)acryloyl groups and the same number of hydroxyl groups obtained by the reaction of an unsaturated carboxylic acid such as meth)acrylic acid with active hydrogen; Glycidyl ether and 2-
A polyfunctional (meth)acrylate having two or more (meth)-acryloyl groups and the same number of hydroxyl groups obtained by an addition reaction of an unsaturated alcohol such as hydroxyethyl (meth)acrylate.

Conversely, compounds obtained by addition reaction between an unsaturated compound having an epoxy group such as glycidyl (meth)acrylate and a compound having active hydrogen such as a saturated or unsaturated carboxylic acid, alcohol, primary or secondary amine, etc. These include polyfunctional (meth)acrylates which have two or more (meth)acryloyl groups and a number of hydroxyl groups not exceeding this number. It is also possible to use two or more types of B components together.

Since these B components have a hydroxyl group in one molecule, they exhibit a certain degree of compatibility with the partially saponified polyvinyl acetate of A component, which is a hydrophilic polymer. Also.

Since it has two or more (meth)acryloyl groups in the same molecule, the crosslinked structure produced by photopolymerization of component B becomes fully six-dimensional and extremely dense. Furthermore, since the number of hydroxyl groups does not exceed the number of (meth)acryloyl groups, it is possible to prevent the water resistance of the resulting crosslinked structure from being degraded by excessive hydroxyl groups. For the above reasons, the water resistance of the photocured portion is good, and it is possible to obtain a high degree of image reproducibility.

If the amount of component B used is, for example, less than 10 parts by weight per 100 parts by weight of component A, the density of the crosslinked structure produced by photopolymerization will be insufficient, making it impossible to obtain good image reproducibility. However, if the amount is 600 parts by weight or more, the crosslinked structure generated by photopolymerization becomes overcrowded, making the photocured part brittle and causing serious problems such as cracking.

Therefore, it is necessary that the amount of component B used is in the range of 10 to 600 parts by weight per 100 parts by weight of component A, and the more preferred amount is 50 to 150 parts by weight.

Since component B has hydroxyl groups in nine molecules, its compatibility with component A is relatively good. However, the molecular weight of 9 is 200
If it exceeds 0, there is a tendency for the compatibility to drop sharply, so the molecular weight of component B is preferably 2000 or less.

Examples of the saturated compound having a hydroxyl group in the molecule having a molecular weight of 1000 or less and a boiling point of 150° C. or more as component C include the following compounds.

n-hexyl alcohol, benzyl alcohol.

Inheptyl alcohol, n-octyl alcohol, isooctyl alcohol, n-decyl alcohol, benzyl alcohol, cycloheptyl alcohol, phenyl selon, hexyl cellosolve, 2-methoxymethoxyethanol.

Ethylene glycol, ethylene glycol monoacetate, diethylene glycol, methyl carpitol, ethyl carpitol, phthyl carbitol, diethylene glycol monoacetate),)! J ethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, phlopylene gelicol, diethylene glycol.

Tripropylene glycol, polyethylene glycol with a molecular weight of 100 or less, polypropylene glycol with a molecular weight of 1000 or less, 1,4-buta/diol, 1,5-bentanediol, glycerin, glycerin monoacetate, glycerin diacetate, glycerin monobutylene rate, glycerin diptylate, diglycerin 1. trimethylolmethane, trimethylolethane,
These include trimethylolpropane, hexanetriol, tetramethylolmethane, tetramethylolethane, and triethanolamine. It is also possible to use two or more types of C components together.

The molecular weight of component C needs to be 1000 or less; if it is more than that, the compatibility with components A and B will be poor, so it cannot play a role in improving the compatibility of components A and B. Can not. The reason why the compatibility between the A component and the B component is improved by using the C component is estimated as follows, for example. That is, component B has a hydroxyl group in its molecule, so component A is a hydrophilic polymer.
Although the component B has a certain degree of compatibility with the partially saponified polyvinyl acetate, for example, if the solvent is rapidly removed during printing plate formation, or if the soot is rapidly cooled, a portion of the B component may be removed from the plate surface. It oozes out.

In many cases, the A component and the B component phase separate within the plate material, resulting in cloudiness. Furthermore, if a plate material is stored for a long time under high humidity conditions, development may be observed in which part of the B component gradually seeps into the plate surface. However, when component C is added, component C has a certain degree of compatibility with both component A and component B due to the action of its hydroxyl group, so it helps the compatibility between component A and component B. It is believed that these problems will be resolved by playing a role. Furthermore, by adding the C component, moldability during plate material production is also improved. When, for example, octyl alcohol is used as component C, it can be expected to have the effect of eliminating bubbles generated when a 9-partly saponified polyvinyl acetate plate material is developed with water.

Generally, when a low molecular weight saturated compound such as component C is added to a photosensitive resin composition, photocurability deteriorates, and image reproducibility usually deteriorates rapidly. However, in the case of the present invention, since component B is a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups, the crosslinked structure produced by photopolymerization is sufficiently three-dimensional and has a very high density. Since the crosslinked structure does not contain excess hydroxyl groups, the water resistance of the photocured portion is extremely good. Therefore, even if a relatively large amount of the low molecular weight saturated compound as component C is contained, the water resistance of the photocured portion is only slightly reduced, and a high degree of image reproducibility can be maintained.

If the boiling point of the C component is li, 15Q°C or lower, it will only serve as a solvent for the photosensitive resin composition and will be removed from the plate material during the drying process during plate molding. It cannot play its original role of helping the compatibility between the component and the B component. Further, if the boiling point is 150° C. or lower, when a portion remains inside the plate material, it evaporates over time, causing a significant change in plate hardness over time. For the above reasons, it is necessary that the boiling point of component C be 150°C or higher.

Since the boiling point of the 0 component is 150° C. or higher, all or most of it remains inside the plate even after the plate is molded. Therefore,
It also plays the role of imparting flexibility to the exposure plate, eliminates the problem of cracking in cold weather, and improves ink transferability.

If the amount of component C used is less than 1 part by weight per 100 parts by weight of component A, it will not be able to play a role in promoting compatibility between component A and component B. On the other hand, if it is added in excess of 60 parts by weight, the water resistance of the photo-cured area will deteriorate and cannot be ignored.
Image reproducibility is significantly reduced. From this, it is necessary that the amount of component C used is in the range of 1 to 60 parts by weight, preferably 5 to 50 parts by weight.

All conventionally known compounds can be used as the photosensitizer for quickly carrying out the photopolymerization reaction of the composition of the present invention. For example, benzoin alkyl ethers, be/sophenones, anthraquinones, benzyls,
Acetophenol/class.

Examples include diacetyls. These photosensitizers are
It can be used in a range of 0.01 to 10% by weight based on the total composition.

All known thermal polymerization inhibitors can be used to increase the thermal stability of the compositions of the invention. Preferred thermal polymerization inhibitors include phenols, hydroquinos, catechols, etc. 2 o, o based on the total amount of the composition
It can be used in the range of o i to 5% by weight. Furthermore, dyes, pigments, surfactants, antifoaming agents, ultraviolet absorbers, etc. can also be added.

The usual production of the composition of the present invention involves heating and dissolving partially saponified polyvinyl acetate as component A in a water/alcohol mixed solvent, followed by polyfunctional (meth)acrylate as component B, and saturated polyvinyl acetate having a hydroxyl group as component C. Add the compound, photosensitizer, thermal polymerization inhibitor, etc., and stir to mix thoroughly. In this way, a photosensitive resin solution is obtained.

To form a photosensitive layer from the above mixed solution.

For example, a photosensitive layer can be formed by distilling off the solvent, drying, and then granulating the product onto a support under heat and pressure using a press or the like. It is also possible to form a photosensitive layer by making a photosensitive sheet by a dry film forming method and adhering this sheet onto a support. moreover.

A photosensitive layer can also be obtained by dry film forming directly on the support. Supports include iron, stainless steel, aluminum,
- Metal plates such as copper, synthetic resin sheets such as polyester films, and synthetic rubber sheets such as styrene-butadiene are used. The photosensitive layer is preferably formed to have a thickness of 0.1 to IQ mm.

In order to form a relief image for printing using the photosensitive resin composition of the present invention, a negative or positive original film is closely adhered to the photosensitive layer prepared as described above. High pressure mercury lamp 6
Ultra-high pressure mercury lamps, metal halide lamps, xenon lamps, carbon arc lamps.

It is irradiated with ultraviolet rays from a chemical lamp to cause curing by photopolymerization. Next, a relief is formed on the support by dissolving the uncured portion into water using a spray developing device or a brush developing device using neutral water.

The photosensitive composition of the present invention can be developed with neutral water and is highly suitable for high-grade printing applications that require reproduction of fine images such as 133-line 6-inch mesh and 50μ fine lines. A photosensitive resin plate material having image reproducibility of This is because (meth)acrylate is used, and the saturated compound having a hydroxyl group as component C improves the compatibility of components A and B. In other words, component B has a hydroxyl group in its molecule, so It has a certain degree of compatibility with the partially saponified polyvinyl acetate of component A.

However, their compatibility is not always sufficient, so phase separation and seepage onto the plate surface often occur during molding of one plate material. Adding component C solves this problem, and the component B and component B become completely compatible. This is thought to be because component C has a certain degree of compatibility with component A and component B due to the action of the hydroxyl group in the molecule.0 When the plate material obtained in this way is irradiated with actinic light, Photopolymerization of component B proceeds quickly and uniformly, and component A is
It is uniformly and efficiently included in the dense crosslinked structure produced by photopolymerization of the polyfunctional (meth)acrylate component. Moreover, since the crosslinked structure formed by photopolymerization of component B is completely destroyed by polyfunctional (meth)acrylate, it has a much higher density than when it is mainly composed of monofunctional (meth)acrylate. C. The number of hydroxyl groups in component B.

Since several (meth)acryloyl groups are removed, the crosslinked structure itself has good water resistance. Therefore, even if the C component contains a saturated compound having a hydroxyl group.

The photocured part has good water resistance and a high degree of image reproducibility. In addition, the C component is contained in the plate material after exposure and has the effect of imparting flexibility. As described above, in the photosensitive resin composition of the present invention, each of the three components A, B, and C is an essential component, and by combining these three components, a high degree of image reproducibility and flexibility of the exposure plate can be achieved. It is something that can be done.

The photosensitive composition of the present invention exhibits its effects most when used as a letterpress material, but it is also used as a planographic material.

It can also be used as an intaglio material, stencil material, or photoresist.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 1 mole of propylene glycol diglycidyl ether, 2 moles of acrylic acid, 1% by weight of triethylbenzylammonium chloride, 0% of hydroquinone monomethyl ether
．． 1% by weight was put into a 6-tube flask, heated to 8aC under nitrogen gas flow, and reacted for 8 hours. As a result of examining the infrared absorption spectrum of the obtained reaction product, it was found that there were two hydroxyl groups as shown below.

It was confirmed that a polyfunctional acrylate having two acryloyl groups was produced.

OHOH Partially saponified polyvinyl acetate having a degree of saponification of 80 mol/l and a degree of polymerization of 500 was selected. 100 parts by weight of this partially saponified polyvinyl acetate was mixed with ethanol/water = 50150 (
(weight ratio) was heated and dissolved in a mixed solvent at 80°C. Next, 60 parts by weight of the bifunctional acrylate obtained by the addition reaction of propylene glycol diglycidyl ether and acrylic acid was added.

20 parts by weight of diethylene glycol, 2 parts by weight of dimethylbenzyl ketal as a photosensitizer, and 0.01 part by weight of hydroquino/ as a thermal polymerization inhibitor were added and mixed thoroughly with stirring.

The thus obtained photosensitive resin composition solution was coated with a polyester adhesive in advance to a thickness of 150 mm.
The mixture was cast onto a polyester film having a thickness of 950 μm after drying, including the substrate. Then, the solvent was completely removed by placing it in a hot air oven at 60° C. for 5 hours.

The resulting photosensitive layer was transparent and no monomer seepage was observed on the plate surface.

The surface of the photosensitive layer thus obtained was coated with a thin layer of water/ethanol = 5Q15Q (weight ratio) solvent to a thickness of 100 μm.
A cover film was attached by pressing a polyester film with a thickness of . This plate material was stored in the dark for 10 days.

Peel off the cover film of the plate material and place a grayscale negative film (manufactured by Stouffer) on the X-light layer for sensitivity measurement.
215 teps 5 intensity Guide
) and negative film for image reproducibility evaluation (136
Line, 3 chi.

5 inch and 10 inch halftone dots, diameter 200μ and 300μ independent points 1 width 50μ and 70μ thin line parts) are vacuum-adhered,
Exposure was performed for 2 minutes using a high-pressure mercury lamp.

After exposure, development was carried out using a brush-type washing machine (liquid temperature: 30°C) containing neutral water. After a development time of 2 minutes, the non-image area was completely dissolved into water, and a relief image could be obtained.

As a result of evaluating the obtained relief, it was found that the gray scale part remained up to 16 steps, indicating high sensitivity. It was confirmed that fine details such as 3-chip halftone dots, 200μ independent dots, and 50μ thin lines were completely reproduced in the image area. The hardness of the printing plate was Shore D6.

When a printing test was conducted using the plate material obtained in this way, a sharp printed product was obtained without any thick lines.

Example 2 1 mole of ethylene glycol diglycidyl ether, 2 moles of methacrylic acid, 2% by weight of triethylbenzylammonium chloride, and 0 and 1% by weight of hydroquinone monomethyl ether were placed in a 3-meter flask and reacted at 80°C for 6 hours. The infrared absorption spectrum of the obtained reaction product revealed that a polyfunctional methacrylate having two unsaturated groups and two hydroxyl groups having the following structure was produced.

OHOH As the saponified polyvinyl acetate, one having a degree of saponification of 71 molar and a degree of polymerization of 600 was selected. 100 parts by weight of this partially saponified polyvinyl acetate was dissolved in a mixed solvent of water/ethanol-40/60 (weight ratio) at 90°C. Next, difunctional methacrylate 75 previously obtained by reacting 1 mole of ethylene glycol diglycidyl ether with 2 moles of methacrylic acid.
Weight part.

23 parts by weight of trimethylolpropane, 2 parts by weight of dimethylbenzyl ketal as a photosensitizer, and 0.1 part by weight of hydroquinone monomethyl ether as a thermal polymerization inhibitor were added and thoroughly mixed with stirring.

The photosensitive resin solution thus obtained was coated with epoxy adhesive and placed on a steel base with a thickness of 250μ to a thickness of 700μ after drying (including the steel paste).
It spread like this. Open this at 60°C 4
After some time, the solvent was completely removed.

4 After storing this plate material in a dark place for 5 days, the same test negative film as in the example was vacuum-adhered to the photosensitive layer and exposed to a chemical lamp for 7 minutes. Then, the film was developed using a spray type developer (surface temperature: 5° C., pressure: 3 kg/m”) containing neutral water.

In 4 minutes, the non-image area was completely eluted and a relief image was obtained.

When the obtained relief was evaluated, it was found that the gray scale remained up to 16 steps, indicating high sensitivity. It was found that the image reproduced 6 halftone dots, 200μ independent points, and 50μ thin lines. Printing plate hardness is Shore D
55, and a flexible printing plate was obtained.

Example 3 1 mole of glycidyl methacrylate, 1 mole of acrylic acid, 1 weight s of triphenylphosphine, and 0.1% by weight of hydroquinone monomethyl ether were charged into a 3-Solo flask, and reacted at 80°C for 9 hours. The infrared absorption spectrum of the reactant revealed that a polyfunctional methacrylate having two unsaturated groups and one hydroxyl group as shown below was produced.

OH Partially saponified polyacetic acid bitel with saponification degree of 90 mol.9
One with a degree of polymerization of 800 was selected. 100 parts by weight of this partially saponified polyvinyl acetate was dissolved in a mixed solvent of water/ethanol = 60/40 [weight ratio] at 70°C. Next, 90 parts by weight of bifunctional methacrylate previously obtained by the addition reaction of glycidyl methacrylate and methacrylic acid, 10 parts by weight of ethylene glycol, and 5 parts by weight of benzophenone were added and thoroughly stirred and mixed.

The photosensitive resin solution thus obtained was cast onto a 350 μm thick aluminum substrate coated with an epoxy adhesive in advance so that the thickness after drying was 700 μm (including the substrate). This was placed in an open oven at 60° C. for 2 hours to completely remove the solvent.

The film was exposed to light for 1 minute using a high-pressure mercury lamp. Next.

It was developed for 6 minutes using the same spray type developer as in Example 2 to obtain a relief image.

As a result of evaluating the obtained relief image, it was found that the gray scale portion remained up to 15 steps. The image is 3 dots, 20
It was confirmed that both the 0μ independent point and the 50μ thin line were reproduced without problems. The printing plate hardness was Shore D72C.

A printing test was carried out using this printing plate, and very sharp printed matter was obtained without any thickening of the 9 strokes. Furthermore, no problems such as cracks in the printing plate occurred during printing.

Patent applicant: Toshi Co., Ltd. ,1

Claims (1)

[Claims] (1) A photosensitive resin composition comprising the following components A, B and C. A, Partially saponified polyvinyl acetate with a degree of saponification of 60 to 99 molar 100 parts by weight B0 Molecular weight 2000
In the following, polyfunctional (meth)acrylates have two or more (meth)acryloyl groups in the same molecule and simultaneously have a number of hydroxyl groups not exceeding the number of (meth)acryloyl groups.
10-300 parts by weight C0 molecular weight 100
1 to 60 parts by weight of a saturated compound having a hydroxyl group in the molecule with a boiling point of 0 or less and a boiling point of 150°C or more