JPH0460549A - Photosensitive resin - Google Patents

Abstract

PURPOSE:To enable development with an aq. soln. for washing out and to ensure satisfactory rubber elasticity and superior printing resistance by bringing a compd. having an ethylenic unsatd. group and an isocyanate group into an addition reaction to a specified copolymer. CONSTITUTION:A copolymer is produced by the conventional soln. polymn. method with polybutadiene having ethylenic unsatd. groups, a compd. having an amino group and an ethylenic unsatd. group and a compd. having a hydroxyl group and an ethylenic unsatd. group. A compd. having an ethylenic unsatd. group and an isocyanate group is brought into an addition reaction to the copolymer to obtain a copolymer as a photosensitive resin having ethylenic unsatd. groups and carboxyl groups. Development with an aq. soln. for washing out is enabled and satisfactory rubber elasticity and printing resistance can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] (Industrial Application Field) The present invention relates to a photosensitive resin that can be developed with an aqueous washout solution and is suitable for making flexographic printing plates.

(Prior Art) In recent years, plates made of photosensitive elastomers have come to be used as rubber plates for flexographic printing.

As such photosensitive resin, Japanese Patent Publication No. 5629260
I can list the ones described in the publication. This is mainly composed of a diene polymer, and development after image exposure is carried out using an organic solvent as a washout liquid. For this reason, they pose various problems such as toxicity to the human body, air pollution, and, depending on the solvent used, a fire hazard.

In order to solve these problems, research is being carried out on photosensitive resins that can be developed with an aqueous developer, and several proposals have been made.

Furthermore, JP-A-61-128243 discloses that a copolymer (A) of a conjugated diene compound, an α,β-ethylenically unsaturated carboxylic acid, and a monoene compound, an N-substituted maleimide resin, and a photopolymerization initiator are used. The technology has been disclosed.

Furthermore, JP-A-1-183651 describes conjugated diene compounds, polyfunctional vinyl compounds, monoolefinic unsaturated compounds, monoolefinic unsaturated compounds, and α,β-ethylenically unsaturated carboxylic acids. A photosensitive resin composition comprising a copolymer comprising a photopolymerizable unsaturated monomer and a photosensitizer is disclosed.

(Problems to be Solved by the Invention) The above technology is characterized in that it attempts to obtain a photosensitive resin that can be developed with an alkaline aqueous solution and has rubber elasticity by introducing a carboxyl group into a backbone polymer.

However, because a low molecular weight polymer is used so that it can be developed with water, the resulting resin has low rubber elasticity, and because it is a mixture of a polymer and a photopolymerizable monomer that have been photocrosslinked, it cannot be used as a solvent in flexo ink. There were problems with printing durability due to swelling.

[Structure of the Invention] (Means for Solving the Problem) In order to create a flexographic printing plate that can be developed with conventional water or an aqueous washout solution, research has been carried out to solve various problems with photosensitive resins. As a result, polybutadiene (a) having an ethylenically unsaturated group, a compound (b) having an amino group and an ethylenically unsaturated group, and a compound (C) having a hydroxyl group and an ethylenically unsaturated group were copolymerized. The resulting copolymer can be developed with a photosensitive resin obtained by addition-reacting a compound (d) having an ethyl unsaturated group and an isonic acid group, with water, or with an aqueous washout solution,
Moreover, it was found that it exhibited excellent properties as a flexographic printing plate, had sufficient rubber elasticity, and had excellent printing durability.

In other words, polymers that can be developed with water or an aqueous developer have photocrosslinking properties, so whether they are used alone or mixed with a photocrosslinkable monomer, they will have sufficient water resistance and printing durability after exposure. We have it.

Examples of the polybutadiene (a) having an ethylenically unsaturated group in the present invention include those obtained by introducing an acryloyl group or a methacryloyl group into the hydroxyl group of a liquid polybutadiene having a hydroxyl group at the end through an ester bond or a urethane bond.

In addition, compounds having an amino group and an ethylenically unsaturated group (
Examples of b) include 2,2''-dimethylaminoethyl acrylate, 2.2'-dimethylaminoethyl methacrylate, 2.2'-dimethylaminoethyl acrylate, 2,2'-diethylaminoethyl methacrylate, and the like.

Examples of the compound (C) having a hydroxyl group and an ethylenically unsaturated group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, caprolactone adduct of 2-hydroxyethyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. Examples include hydroxy 3-phenoxypropyl acrylate, N-(2-hydroxyethyl) methacrylamide, and the like.

In the present invention, polybutadiene (a) having an ethylenically unsaturated group, a compound (b) having an amino group and an ethylenically unsaturated group, and a compound (C) having a hydroxyl group and an ethylenically unsaturated group are usually Copolymer (e) is prepared using the solution polymerization method.

Preferred as the copolymer (e) is poly9tadiene (a) having an ethylenically unsaturated group: 40 to 90 weight 06
, a compound (b) having an amino group and an ethylenically unsaturated group
: 5 to 40% by weight, Compound (c) having a hydroxyl group and an ethylenically unsaturated group: 1 to 40% by weight.

Polybutadiene (a) or 4 having ethylenically unsaturated groups
If the weight is less than 06, it is difficult to obtain sufficient rubber elasticity.
If the weight is 90.06 or more, even if sufficient rubber elasticity is obtained, the viscosity of the solution becomes high, resulting in poor developability.

If the amount of the compound (b) having an amino group and an ethylenically unsaturated group is 5% by weight or less, the developability will be poor, and if the amount is 40% by weight or less,
In this case, the water resistance will deteriorate.

Also, a compound (C) having a hydroxyl group and an ethylenically unsaturated group
is used to add an ethylenically unsaturated group using a urethane reaction after producing the copolymer (e), and is used at a concentration of 1% by weight.
In the following cases, it will no longer have photocrosslinking properties, and 40 weight 06
In the above case, it no longer has rubber elasticity.

Polybutadiene (a) having an ethylenically unsaturated group, a compound (b) having an amino group and an ethylenically unsaturated group, and a compound (C) having a hydroxyl group and an ethylenically unsaturated group
The molecular weight of the copolymer (e) obtained by copolymerizing is
The number average molecular weight is preferably in the range of 2,000 to 50,000; if it is less than 2,000, sufficient rubber elasticity cannot be obtained;
If it is more than 00, sufficient developability cannot be obtained.

In the present invention, the above copolymer (e) is subjected to an addition reaction with a compound (d) having an ethylenically unsaturated group and an isocyanate group.

The compound (d) having an ethylenically unsaturated group and an isocyanate group can be obtained by subjecting the hydroxyl group of the above-mentioned compound (C) having a hydroxyl group and an ethylenically unsaturated group to an addition reaction with a diisocyanate. Examples of diisocyanates include 2,4-tolylene diisocyanate, o,
m, p-xylylene diisocyanate, isophorone diisocyanate, 4,4°-diphenylmethane diisonanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, 2,4-phenylene diisocyanate, and the like.

The reaction of the compound (d) having a hydroxyl group and an ethylenically unsaturated group with a diisocyanate is preferably carried out at a ratio of 1 mole to I mole at a temperature of 100° C. or lower where the ethylenically unsaturated group is not crosslinked.

The reaction between the compound (d) having an ethylenically unsaturated group and an isocyanate group and the hydroxyl group of the copolymer (e) is as follows:
It is also preferable to carry out the reaction at a temperature of 100°C or lower so that the ethylenically unsaturated groups are not crosslinked.

In this way, a copolymer (f), which is a photosensitive resin having an ethylenically unsaturated group and a carboxyl group, is obtained.

Copolymer (f), which is a photosensitive resin, can be used as a dispersion by dissolving or dispersing it in a solvent, or can be used as a dispersion by dissolving or dispersing it in a solvent.
) may be used alone or may be mixed with the compound (g) having an ethylenically unsaturated group as a photosensitive resin composition.

As the ethylenically unsaturated compound (g), acrylic acid,
Monocarboxylic acids such as methacrylic acid, 2-hydroxylethyl methacrylate, styrene.

α-methylstyrene, vinyltoluene, (meth)acrylonitrile, acrylic ester, methacrylic ester, acrylic amide, methacrylic amide, etc., and one or more of these ethylenically unsaturated compounds (g) They can be used in combination.

A photopolymerization initiator is usually used in this photosensitive resin.

The preferred amount of photopolymerization initiator added is 1% to the total composition.
~20% by weight.

Examples of the photopolymerization initiator used in the present invention include benzoin methyl ether, benzoin ethyl ether, α-methylolbenzoin, α-methylolbenzoin methyl ether, benzoin phenyl ether, 2.2-jetoxyphenylacetophenone, 2.2-jetoxy Examples include hengeine and derivatives thereof such as acetophenone, benzophenone, anthraquinone, and 2-dityl anthraquinone.

Such a photopolymerization initiator is preferably added in an amount of 0.1 to 10.06% by weight based on the solid content.

Moreover, the photosensitive resin of the present invention has 0. O1-5 may contain a thermal polymerization inhibitor of 96% by weight. Examples of the thermal polymerization inhibitor include 2,6-di-t-butyl-p-cresosol, p-cresosol, p-methoxyphenol, hydroquinone, t-butylcatechol, and t-butylhydroxyanisole. Ru.

Furthermore, since the photosensitive resin of the present invention has amino groups even after exposure, it is possible to develop it in an acid aqueous solution, or in order to develop it in water, the amino groups of the copolymer (f), which is the photosensitive resin, can be removed with an acid aqueous solution in advance. You can also neutralize it with

For example, the copolymer (f) may be acetone, 1,2-jethoxyethane, acetonyl acetone, γ-butyrolactone, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, ethylene glycol monoethyl ether acetate. , diethylene glycol monoethyl ether acetate, etc., and then prepared in a solvent containing a hydrophilic solvent such as formic acid, acetic acid, propionic acid, butyric acid, hydrochloric acid, sulfuric acid, nitric acid, hydrochloric acid, acrylic acid, methacrylic acid, etc. It is neutralized by adding an aqueous solution such as an acid.

The solution of the photosensitive resin of the present invention can be cast onto a polyester film in a mold to evaporate the solvent to form a photosensitive resin sheet, and this sheet can be further pressed or calendered for precision. It can also be used as a photosensitive resin sheet with good properties.

At this time, since stickiness may appear depending on the composition, a thin polyester film, polyethylene film, nylon film, etc. may be used as a protective film.

Examples of the active light source used to insolubilize the photosensitive resin of the present invention in a developer include a low-pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, and a xenon lamp.

After exposing the photosensitive resin of the present invention to the light source as described above, the developer used to elute the unexposed areas removes the unexposed areas and has little effect on the image areas that have been exposed. It is necessary that it is something that does not give.

The composition of the developer is mainly water, and may also contain acids such as acetic acid, propionic acid, formic acid, methacrylic acid, and hydrochloric acid, and solvents such as methanol, ethanol, and isopropanol.

The temperature of the developer may be about 25°C, or preferably about 50 to 70°C in order to improve developability.

(Example) Hereinafter, the present invention will be explained in detail with reference to Examples.

In addition, "parts" in the examples indicate "parts by weight."

Example 1 A flask was charged with 174 parts of 2.4-h rylene isonanate, 130 parts of 2-hydroxyethyl methacrylate, 0.3 part of tin octoate, and 0.3 part of hydroquinodi.

The reaction was carried out in a nitrogen atmosphere at 70°C for 4 hours to obtain an isocyanate (A) having a double bond, which is a compound having an ethylenically unsaturated group and an isocyanate group.

Meanwhile, in another flask, liquid polybutanoene having a hydroxyl group at the end (manufactured by Idemitsu Petrochemical Co., Ltd., Poly bd
R-45HT), 180.4 parts of isocyanate (
19.6 parts of A), 0.3 parts of tin octoate, and 50 parts of methyl ethyl ketone (hereinafter abbreviated as MEK) were charged.

The reaction was carried out in a nitrogen atmosphere at 70° C. for 14 hours to obtain modified polybutadiene (B), which is a polybutadiene having an ethylenically unsaturated group.

In addition, add 2 of the above polybutadiene (B) to another flask.
7.26 parts, 9.1 parts of 2-hydroxyethyl methacrylate, a compound having a hydroxyl group and an ethylenically unsaturated group.
3 parts, 15.06 parts of 2,2'-dimethylaminoethyl methacrylate, which is a compound having an amino group and an ethylenically unsaturated group, +54.55 parts of MEK, and N
, 0.5 part of N-azohisisobutyronitrile was charged, and the mixture was reacted at 80°C for 4 hours in a nitrogen atmosphere. Thereafter, the mixture was cooled to 40°C, 0.3 part of hydroquinone was added, and the mixture was thoroughly stirred.

After that, 3.2 parts of isocyanate (A) and 0.05 parts of tin octoate were added to the flask and reacted at 70°C for 4 hours, then 0.2 parts of hydroquinone was added and stirred thoroughly. A photosensitive resin solution (C) was obtained.

To 100 parts of photosensitive resin solution (C), add 0.5 parts of benzophenone and stir thoroughly to make photosensitive resin solution (D).
I got it.

A frame was made on a Teflon board by attaching it with adhesive using Teflon with a thickness of 3 mm. Pour the photosensitive resin solution (D) into this frame, leave it at room temperature for 2 hours, and then heat it to 60°C for 5 hours.
Dry for an hour.

Peel the resin sheet from the Teflon plate to make a photosensitive resin plate (E)
I got it.

A negative film was placed on top of this photosensitive resin plate (E), and a Toshiba 2KW ultraviolet lamp was used to illuminate the film from the negative film side.
Irradiation was performed with an energy of 0 mJ/cm2. The negative film was peeled off, washed out with a brush together with a 3% acetic acid aqueous solution, and thoroughly dried to obtain Sample 1.

Example 2 When preparing solution (C) in Example I, MEKI54.
A solution (C) was prepared in the same manner as in Example 1 using a mixed solvent of 77.28 parts of MEK and 77.27 parts of ethylene glycol monomethyl ether acetate (hereinafter abbreviated as MCA) instead of 55 parts. Thereafter, 7 g of sodium carbonate was dissolved in 20 g of water, added to the flask, and stirred for 20 minutes.

In the same manner as in [Example], benzophenone was added and poured onto a Teflon plate to obtain a photosensitive resin plate.

Thereafter, it was irradiated with an ultraviolet lamp in the same manner as in Example 1.

Sample 2 was obtained by peeling off the negative film, washing it out with a brush with water, and thoroughly drying it.

Example 3 Sample 3 was obtained in the same manner as in Example I, except that 168 parts of hexamethylene diisocyanate was used instead of 4 parts of 2.4-tolylene diyrananate.

Example 4 Sample 4 was obtained in the same manner as in Example 1 except that acrylic acid was used instead of methacrylic acid.

Example 5 Sample 5 was obtained in the same manner as in Example 1 except that Poly bd R-15HT (terminated hydroxyl group liquid polybutadiene manufactured by Idemitsu Petrochemical Co., Ltd.) was used instead of Poly bd R-45HT.

Comparative Example 1 A flask was charged with 174 parts of 2.41 lylene diisocyanate, 130 parts of 2-hydroxyethyl methacrylate, 0.3 part of tin octoate, and 0.3 part of hydroquinone.

The reaction was carried out in a nitrogen atmosphere at 70'C for 4 hours to obtain an isocyanate (A) having a double bond.

In another flask, liquid polybutadiene without hydroxyl groups (
27.26 parts of Nippon Petrochemical Co., Ltd. B-3000), 9.13 parts of 2-hydroquine ethyl methacrylate,
2,2゛-dimethylaminomethacrylate acid to 15
．． 06 parts, 154.55 parts of toluene, and N, N'
-0.5 part of azohisisobutyronitrile was added, and the mixture was reacted for 4 hours at 80'C in a nitrogen atmosphere. After that, 4
After cooling to 0'C, 0.3 part of hydroquinone was added and thoroughly stirred. Then, 3.2 parts of incyanate (A) and 0.05 parts of tin octoate were added to the flask and
After reacting for 4 hours at 'C, 0.2 part of hydroquinone was added and thoroughly stirred to obtain a solution (C).

0.5 part of benzophenone was added to 100 parts of solution (C) and thoroughly stirred to obtain a photosensitive resin solution (D).

A frame was made on a large Teflon board using 3mm thick Teflon and adhesive. Pour the photosensitive resin solution (D) into this frame, leave it at room temperature for 2 hours, and then
It was dried for 5 hours. The resin sheet was peeled off from the Teflon plate to obtain a photosensitive resin plate (E).

A negative film was placed on top of this photosensitive resin plate (E), and a Toshiba 2KW ultraviolet lamp was used to illuminate the film from the film side.
Irradiation was performed with an energy of 0 mJ/cm2.

Comparative sample 1 was obtained by peeling off the negative film and washing it out with a brush together with an aqueous solution of 3Q45 acetic acid.

The results of measuring the physical properties of each sample obtained in Examples and Comparative Examples are shown below.

Rubber hardness: Adjust the thickness of each sample to 2 mm and
e Measured with A rubber hardness meter (manufactured by TECL OCK CORPORATION) Swelling rate: Each sample was 2 cm x 2 c with a thickness of 1 mm.
The sample was adjusted to a size of m and immersed in water at 25°C for 24 hours, and the weight increase was expressed as a percentage.

Resolution: After overlaying each sample with the negative film of "UGRA's Test Chart" and irradiating it with ultraviolet rays, the resolution limit after aqueous development was indicated using the micron meter of "UGRA's Test Chart".

Water developability: Relative evaluation of ease of washing out with water or an aqueous developer after irradiating each sample with ultraviolet rays.

(Effect of the invention) The photosensitive resin of the present invention can be washed out with an aqueous developer,
Moreover, a flexographic printing plate having sufficient rubber elasticity and printing durability can be provided.

In addition, it can also be used for photoresists and screens.

Claims (1)

[Claims] 1. Polybutadiene (a) having an ethylenically unsaturated group
, a compound (b) having an amino group and an ethylenically unsaturated group
, and compounds having a hydroxyl group and an ethylenically unsaturated group (
A photosensitive resin obtained by adding a compound (d) having an ethylenically unsaturated group and an isocyanate group to a copolymer obtained by copolymerizing c). 2. Compounds having an amino group and an ethylenically unsaturated group (b
2. The photosensitive resin according to claim 1, wherein the amino group of ) is neutralized with an acid.