JPH09216918A - Hydrophilic copolymer, process for producing the same, photosensitive composition, and photosensitive rubber plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive compsn. excellent in processability and a photosensitive rubber plate which can be rapidly washed with water in the development and which is useful as a flexographic plate. SOLUTION: The photosensitive composition comprises 20 to 65 pts.wt. of an elastomer, 35 to 80 pts.wt. of a hydrophilic polymer (the sum of the elastomer and the hydrophilic copolymer being 100 pts.wt.), 5 to 100 pts.wt. of a photopolymerizable ethylenically unsatd. monomer, and 0.1 to 10 pts.wt. of a photopolymn. initiator. The hydrophilic copolymer is obtd. by the radical copolymn. of (1) 1 to 30wt.% of a monoethylenically unsatd. monomer containing phosphorus, boron or sulfur, (2) 0.5 to 25wt.% of a diethylenically unsatd. monomer containing phosphorus, boron or sulfur, (3) 40 to 90wt.% of a conjugated diene monomer, and 0 to 58.5wt.% of other monomers.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hydrophilic copolymer,
The present invention relates to a method for producing the same, a photosensitive composition containing the same, and a photosensitive rubber plate obtained from the photosensitive composition. More specifically, the present invention relates to a photosensitive composition having excellent processability, a photosensitive rubber plate having a high water washing rate during development, a hydrophilic copolymer used in the production thereof, and a method for producing the same.

[0002]

2. Description of the Related Art In flexographic printing plates, a printing film is adhered to a photosensitive plate surface, a part of the photosensitive layer is exposed by irradiating with active light, and then an unexposed part is washed away to form a relief. Manufactured. A material for a photosensitive layer of a photosensitive rubber plate such as a flexographic printing plate is required to have a high cleaning speed for facilitating relief formation after exposure.

Materials for the photosensitive layer are mainly composed of an elastomer such as a styrene-butadiene block copolymer or a styrene-isoprene block copolymer and a hydrophilic copolymer containing a carboxy group, and a photopolymerizable ethylenic monomer. A photosensitive elastomer composition containing a body is known. However, the photosensitive rubber plate using this photosensitive elastomer composition has a problem that the cleaning speed after exposure is slow.

In order to overcome the above problems and obtain a photosensitive rubber plate having a high water washing rate, a monoethylenically unsaturated monomer containing a phosphoric acid ester group as an essential monomer unit is used as a hydrophilic copolymer. A photosensitive elastomer composition containing a phosphoric acid ester group-containing copolymer as a main component has been proposed (WO9
4/23342). This composition has an excellent balance between transparency and strength as well as excellent water washing speed.

[0005]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a photosensitive composition excellent in processability, a photosensitive rubber plate having a high water washing rate at the time of development, a hydrophilic copolymer used for the production thereof and a hydrophilic copolymer thereof. To provide a manufacturing method.

The inventors of the present invention have described the above-mentioned WO94 / 23342.
In order to further increase the washing speed with water and to improve the processability when kneading components such as hydrophilic copolymers, the inventors have conducted extensive studies to improve the hydrophilic cohesion. As a polymer, a monomer composition containing a monoethylenically unsaturated monomer containing phosphorus, boron or sulfur and a diethylenically unsaturated monomer containing phosphorus, boron or sulfur as essential monomers By using a copolymer obtained by radical copolymerization, it was found that the water washing rate can be increased and the processability can be improved, and the present invention has been completed based on this finding.

[0007]

Thus, according to the present invention, (1) 1 to 30% by weight of a monoethylenically unsaturated monomer containing phosphorus, boron or sulfur, (2) phosphorus, boron or sulfur 0.5-containing diethylenically unsaturated monomer
25% by weight, (3) conjugated diene monomer 40 to 90% by weight
And a hydrophilic copolymer obtained by radical copolymerizing 0 to 58.5% by weight of another monomer.

Further, according to the present invention, (A) 20 to 65 parts by weight of elastomer, (B) the above hydrophilic polymer 35.
To 80 parts by weight (however, the total amount of the elastomer and the hydrophilic copolymer is 100 parts by weight), (C) 5 to 100 parts by weight of the photopolymerizable ethylenically unsaturated monomer, and (D) light. A photosensitive composition containing 0.1 to 10 parts by weight of a polymerization initiator is provided.

Further, according to the present invention, there is provided a photosensitive rubber plate having a laminated structure comprising a support and a layer of the above-mentioned photosensitive composition formed on the main surface thereof.

Further, according to the present invention, an oxo acid containing phosphorus, boron or sulfur or a salt thereof is reacted with a hydroxyl group-containing ethylenically unsaturated monomer or a corresponding alkoxide to esterify the resulting esterified product. 5-3
Provided is a method for producing a hydrophilic copolymer, which comprises radically copolymerizing 0.5% by weight, 40 to 90% by weight of a conjugated diene monomer and 0 to 58.5% by weight of another monomer.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The photosensitive composition of the present invention contains an elastomer, a hydrophilic copolymer, a photopolymerizable ethylenically unsaturated monomer and a photopolymerization initiator. The hydrophilic copolymer used in the photosensitive composition of the present invention is a monoethylenically unsaturated monomer containing phosphorus, boron or sulfur, a diethylenically unsaturated monomer containing phosphorus, boron or sulfur, Conjugated diene monomer and, as an optional component,
It can be obtained by radically copolymerizing other monomers.

Typical examples of phosphorus-containing monoethylenically unsaturated monomers include phosphoric acid ester group-containing monoethylenically unsaturated monomers and phosphono groups (O = P (OH) _2- ).
Including monoethylenically unsaturated monomers.

The phosphoric acid ester group-containing monoethylenically unsaturated monomer is represented by the following formula (1)

[0014]

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(In the formula, R ¹ is hydrogen or a methyl group, R ² and R ³ are each independently hydrogen or an alkyl group having preferably 1 to 8 carbon atoms, and m and n
Are each independently an integer of 1 to 20. ), Phosphoric acid ester group-containing monoacrylate or monomethacrylate, and specific examples thereof include phosphoric acid ethylene acrylate, phosphoric acid trimethylene acrylate, phosphoric acid propylene acrylate, phosphoric acid tetramethylene acrylate, phosphoric acid diethylene glycol acrylate, and phosphoric acid triethylene glycol acrylate. , Polyethylene glycol acrylate phosphates and their corresponding methacrylates. Of these, ethylene acrylate phosphate, propylene acrylate phosphate and their corresponding methacrylates are preferred. Specific examples of the phosphono group-containing monoethylenically unsaturated monomer include vinylphosphonic acid, diethylvinylphosphonic acid, phenylvinylphosphonic acid, dimethylvinylphosphonic acid,
Di-n-butylvinylphosphonic acid, diisobutylvinylphosphonic acid, diisopropylvinylphosphonic acid and the like can be mentioned.

Specific examples of the monoethylenically unsaturated monomer containing boron include bornyl group-containing methacrylates such as bornyl methacrylate and 2-bornylethyl methacrylate.

Specific examples of the monoethylenically unsaturated monomer containing sulfur include vinyl sulfonic acid, 2-sulfoethyl methacrylate, sodium styrene sulfonate, and 2
-Sulfonic acids such as ethyl methacrylate, vinyl butyl sulfonate, and sulfonates, sulfones such as vinyl sulfone, sulfoxides such as vinyl sulfoxide, and sulfides such as 1- (2-hydroxyethylthio) butadiene. .

The monoethylenically unsaturated monomer containing phosphorus, boron or sulfur may be used alone or in combination of two or more kinds. The amount of monoethylenically unsaturated monomer containing phosphorus, boron or sulfur is from 1 to 30 based on the total weight of all monomers used to obtain the hydrophilic copolymer.
%, Preferably 2 to 20% by weight.

A typical example of the phosphorus-containing diethylenically unsaturated monomer is a phosphoric acid ester group-containing diethylenically unsaturated monomer, which is generally represented by the following formula (2):

[0020]

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(In the formula, R ⁴ and R ⁵ are each independently hydrogen or a methyl group, and R ⁶ , R ⁷ , R ⁸ and R ⁹ are each independently hydrogen or preferably an alkyl having 1 to 8 carbon atoms. Group, and k, l, m and n are each independently an integer of 1 to 20.) A bisacrylate or bismethacrylate containing a phosphoric acid ester group is included. Specific examples of the phosphoric acid ester group-containing bisacrylate or bismethacrylate represented by the formula (2) include phosphoric acid bisethylene acrylate, phosphoric acid bistrimethylene acrylate, phosphoric acid bistetramethylene acrylate, phosphoric acid bisdiethylene glycol acrylate,
Examples thereof include bistriethylene glycol acrylate phosphate and bispolyethylene glycol acrylate phosphate. Of these, bisethylene acrylate phosphate, bispropylene acrylate phosphate and their corresponding methacrylates are preferred.

The amount of the phosphoric acid ester group-containing diethylenically unsaturated monomer is 0.5 to 25% by weight, preferably 1 based on the total weight of all the monomers used for obtaining the hydrophilic copolymer.
-20% by weight.

The weight ratio of the monoethylenically unsaturated monomer containing phosphoric acid, boron or sulfur to the diethylenically unsaturated monomer containing boron or sulfur is usually 90.
/ 10 to 20/80, preferably 85/15 to 30/7
0.

The total amount of the monoethylenically unsaturated monomer containing phosphorus, boron or sulfur and the diethylenically unsaturated monomer containing phosphorus, boron or sulfur is the hydrophilic copolymer. It is usually 5 to 30.5% by weight, preferably 5 to 22% by weight, based on the total weight of all the monomers used for obtaining. If it is less than 5% by weight, the washing speed of the photosensitive rubber plate obtained using the photosensitive composition tends to decrease. If it exceeds 30% by weight, the processability of the photosensitive composition and the aqueous ink resistance of the photosensitive rubber plate tend to decrease.

The monoethylenically unsaturated monomer containing phosphorus, boron or sulfur and the diethylenically unsaturated monomer containing phosphorus, boron or sulfur used in the present invention should be prepared separately. However, both can be used in the form of a mixture. That is, phosphorus,
By reacting an oxo acid or a salt thereof containing boron or sulfur with a hydroxyl group-containing ethylenically unsaturated monomer or a corresponding alkoxide, and esterifying,
A mixture of a monoethylenically unsaturated monomer containing phosphorus, boron or sulfur and a diethylenically unsaturated monomer containing phosphorus, boron or sulfur is produced, and this mixture should be used as a copolymerization starting material. You can

Examples of the oxo acids containing phosphorus, boron or sulfur or salts thereof include phosphoric acid, phosphonic acid, boric acid, sulfuric acid, peroxomonosulfuric acid, disulfuric acid, peroxodisulfuric acid and their sodium salts and potassium salts. You can Of these, phosphoric acid is preferably used.

Examples of the hydroxyl group-containing ethylenically unsaturated monomer or alkoxide thereof include hydroxyethyl methacrylate, hydroxymethyl methacrylate, hydroxymethyl acrylate and hydroxyethyl acrylate.

The esterification reaction of the oxo acid or its salt containing phosphorus, boron or sulfur with the hydroxyl group-containing ethylenically unsaturated monomer or the corresponding alkoxide can be carried out in the same manner as a usual esterification reaction. A commonly used catalyst, solvent or the like can be used.

The ratio of the monoethylenically unsaturated monomer to the diethylenically unsaturated monomer is controlled by controlling the reaction ratio between the oxo acid or its salt and the hydroxyl group-containing ethylenically unsaturated monomer or the corresponding alkoxide. Alternatively, or after reacting the oxo acid or a salt thereof with a hydroxyl group-containing ethylenically unsaturated monomer or a corresponding alkoxide, water or the like may be added to cause hydrolysis to be adjusted.

As the conjugated diene monomer, 1,3-butadiene, isoprene, chloroprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 1,3
-Hexadiene and the like, especially 1,3-
Butadiene and isoprene are preferably used. These conjugated diene monomers can be used alone or in combination of two or more. The amount of the conjugated diene monomer is usually 40 to 90% by weight, preferably 50 to 80% by weight, based on the total weight of all the monomers used for obtaining the hydrophilic copolymer. If the amount is less than 40% by weight, the strength of the photosensitive rubber plate is reduced. If the content exceeds 90% by weight, the cleaning speed of the photosensitive rubber plate is reduced.

Other monomers used as an optional component for obtaining the hydrophilic copolymer include ethylenically unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; maleic acid, fumaric acid, citraconic acid and itaconic acid. Ethylenically unsaturated polycarboxylic acid such as; methyl acrylate, ethyl acrylate, propyl acrylate, n-amyl acrylate, isoamyl acrylate, hexyl acrylate, ethylhexyl acrylate, octyl acrylate, methyl methacrylate, methacryl Alkyl esters of ethylenically unsaturated monocarboxylic acids such as ethyl acrylate, propyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, ethylhexyl methacrylate, octyl methacrylate; glycidyl acrylate, acrylate methacrylate Glycidyl esters of ethylenically unsaturated monocarboxylic acids such as sidyl; hydroxyalkyl esters of ethylenically unsaturated monocarboxylic acids such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate; monoethyl maleate , Partial esterification products of ethylenically unsaturated polycarboxylic acid such as monomethyl itaconate; vinyl cyanide monomers such as methacrylonitrile and acrylonitrile; styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene,
Aromatic vinyl monomers such as p-tert-butylstyrene, 1,3-dimethylstyrene, chlorostyrene, vinylnaphthalene, and vinylanthracene; and ethylenically unsaturated glycidyl ethers such as allyl glycidyl ether; and the like.

The above-mentioned monomers used as an optional component may be used alone or in combination of two or more kinds, and the amount used is based on the total weight of all the monomers used for obtaining the hydrophilic copolymer. 58.5% by weight or less, preferably 55% by weight or less.

It is preferable to use a polyfunctional ethylenically unsaturated monomer in order to enhance the processability of the photosensitive composition and the transparency and strength of the photosensitive rubber plate. Specific examples of the polyfunctional ethylenically unsaturated monomer include acrylic acid esters of polyhydric alcohols such as ethylene glycol diacrylate, trimethylolpropane triacrylate and propylene glycol diacrylate, and corresponding methacrylic acid esters; Examples include polyfunctional aromatic vinyl monomers such as vinylbenzene. Of these polyfunctional ethylenically unsaturated monomers, ethylene glycol dimethacrylate and divinylbenzene are preferred. The amount of polyfunctional ethylenically unsaturated monomer is
It is usually 10% by weight or less based on the total weight of all the monomers used for obtaining the hydrophilic copolymer.

The hydrophilic copolymer used in the present invention is obtained by radical polymerization, preferably emulsion polymerization, of the above-mentioned monomer. The initiator and emulsifier used for the polymerization are not particularly limited. The hydrophilic copolymer obtained by the above copolymerization can be represented by the following formula (3).

[0035]

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In the formula, R ¹ , R ⁴ and R ⁵ are each independently hydrogen or a methyl group, A and B are each independently a functional group containing phosphorus, boron or sulfur, and D
Is a conjugated diene unit, E is another monomer unit,
a, b, d and e are the number of moles of each repeating unit and satisfy the following weight ratios, respectively. a / (a + b + e + d) = 1 to 30, preferably 2 to 2
0 b / (a + b + e + d) = 0.5 to 25, preferably 1
-20 d / (a + b + e + d) = 40-90, preferably 50
~ 80 e / (a + b + e + d) = 0 to 58.5

A in the above formula (3) is preferably the following formula (4)

[0038]

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(In the formula, R ² , R ³ , m and n are represented by the formula (1)
It is the same as the one in the above). B in the above (3) is preferably the following formula (5)

[0040]

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(R ⁶ , R ⁷ , R ⁸ , R ⁹ , k, l, m in the formula
And n are the same as those in the formula (2)) and represent a phosphoric acid ester group-containing diacyloxy group.

From the viewpoint of improving the processability of the photosensitive composition and the strength of the photosensitive rubber plate, the hydrophilic copolymer used in the present invention usually has a gel content of 50-100%, preferably 60-. 100%, more preferably 70 to 10
0%. The gel content was such that the granular or flocked hydrophilic copolymer (weight A) was put in a 100-mesh wire netting basket and placed in a tetrahydrofuran solvent at 20 ° C. for 24 hours.
After soaking for a period of time, it is dried and weighed (weight B). Gel content (%) =
(B / A) x 100

The elastomer used in the photosensitive composition of the present invention includes a block copolymer composed of polystyrene block A and polybutadiene block B, a block copolymer composed of polystyrene block A and polyisoprene block B, and styrene and butadiene. SB random copolymer having as essential monomer units, NB random copolymer having acrylonitrile and butadiene as essential monomer units, styrene-isoprene copolymer, methyl methacrylate-butadiene copolymer, etc. Examples thereof include random copolymers, polybutadiene, polyisoprene, and natural rubber.

Among these elastomers, a block copolymer is preferable, and in particular, a polymer block A composed of a polymer having an aromatic vinyl monomer as a main constituent unit, a conjugated diene as an essential constituent unit, and the conjugated diene unit portion. The polymer block B comprising a conjugated diene-based polymer having a vinyl bond content of 10 to 70%, preferably 20 to 70% is preferable.

The weight average molecular weight of the polymer block A is usually 3,000 to 200,000, preferably 8,000.
It is 0 to 100,000. The weight average molecular weight of the polymer block B is usually 5,000 to 500,000, preferably 10,000 to 300,000. The weight average molecular weight of the entire block copolymer is usually 8,000 to
2,000,000, preferably 18,000 to 1,0
It is about 100,000. The weight average molecular weight is a value measured using gel permeation chromatography (hereinafter abbreviated as GPC) and converted into the molecular weight of standard polystyrene.

In the polymer block B, the vinyl bond content of the conjugated diene unit portion of the polymer constituting the polymer block is usually
10 to 70%, preferably 20 to 55%.
When the vinyl bond content is less than 10%, the transparency of the photosensitive rubber plate is lowered, the strength balance is deteriorated, and the washing speed is slowed. If it exceeds 70%, the strength of the photosensitive rubber plate decreases.

The vinyl bond content is 1,2-bond, 3,4-bond or 1,4-bond conjugated diene incorporated into the polymer block B.
-Percentage of conjugated dienes incorporated in linked and 3,4-linked modes of attachment. The vinyl bond content is a value measured using a nuclear magnetic resonance apparatus.

The weight ratio of the polymer block A and the polymer block B is usually (polymer block A / polymer block B =) 5/95 to 95/5, preferably 10/90 to 9
0/10, and more preferably 15/85 to 75/25.

The block copolymer as an elastomer used in the photosensitive composition of the present invention is not limited by the combined structure of the polymer block A and the polymer block B. For example, the general formula (AB) _n -A , (A−B) _n −A−B,
_{B- (A-B) n -A} -B, (A-B) n -X, ((A
-B) _n- A) _m- X, (BA- (BA) _n ) _m-
X, (BA- (BA) _n- B) _m- X (wherein A is a polymer block A, B is a polymer block B, X
Is a residue of a coupling agent or a polyfunctional ionic polymerization initiator, n and m are 1 or more, preferably an integer of 1 to 5. Examples of coupling agents include tin tetrachloride, silicon tetrachloride, epoxidized esters, polyvinyl compounds, carboxylic acid esters, polyhalogenated hydrocarbons, and the like.
Examples of the polyfunctional ionic polymerization initiator include polyfunctional organic lithium compounds. ). Among these, those having a structure represented by the general formula ABA are preferable.

The block copolymer as an elastomer used in the present invention can be usually obtained by polymerizing the above-mentioned monomers using a polymerization initiator such as an organic lithium compound. Specifically, a monomer mixture containing an aromatic vinyl monomer as a main component is polymerized to form a polymer block A, and then a monomer mixture containing a conjugated diene as an essential component is added and polymerized. After forming the polymer block B connected to the molecular end of the polymer block A, further adding an aromatic vinyl monomer and polymerizing it to form another polymer block A connected to the polymer block B Alternatively, as described above, the polymer block A and the polymer block B connected to the polymer block A may be formed, and then a coupling agent may be added.

The adjustment of the vinyl bond content of the polymer block B is not limited by the means. Usually, it is carried out by controlling the amount or type of polar compound used when polymerizing the polymer block B, the polymerization temperature and the like.

The amount of the elastomer in the photosensitive composition of the present invention is 10 in total of the elastomer and the hydrophilic copolymer.
Of 0 parts by weight, 20 to 65 parts by weight, preferably 30 to
60 parts by weight. If the amount exceeds 65 parts by weight, the washing speed of the photosensitive rubber plate obtained by using the photosensitive composition decreases.
On the other hand, if it is less than 20 parts by weight, the processability of the photosensitive composition and the water-based ink resistance of the photosensitive rubber plate are lowered.

The photopolymerizable ethylenically unsaturated monomer used in the photosensitive composition of the present invention is in a liquid or solid state at room temperature. Specifically, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, pt
tert-butylstyrene, 1,3-dimethylstyrene,
Aromatic vinyl monomers such as chlorostyrene, vinylnaphthalene, vinylanthracene, divinylbenzene and trivinylbenzene; ethylenically unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile; methyl acrylate, ethyl acrylate, acrylic acid Propyl, n-amyl acrylate, isoamyl acrylate, hexyl acrylate, ethylhexyl acrylate, octyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, Hexyl methacrylate, ethylhexyl methacrylate, octyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydromethacrylate Shipuropiru, glycidyl methacrylate, ethylene glycol diacrylate, trimethylolpropane triacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, propylene glycol diacrylate, 1,6
Hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol diacrylate, 1,9-nonanediol dimethacrylate, methoxyethylene glycol acrylate, methoxypropylene glycol methacrylate, methoxyethylene glycol methacrylate, methoxypropylene glycol Ethylenically unsaturated carboxylic acid ester monomers such as acrylate, diethyl maleate and dimethyl itaconate; Ethylenically unsaturated glycidyl ethers such as allyl glycidyl ether; Ethylenically unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; Malein Acid, fumaric acid, citraconic acid, itaconic acid and other ethylenically unsaturated polycarboxylic acids; monoethyl maleate, monomethyl itaconate, etc. Ethylenic unsaturated polyvalent moiety esters of carboxylic acids; phosphoric acid ethylene acrylate phosphate, trimethylene acrylate, phosphoric propylene acrylate phosphate, tetramethylene acrylate phosphate bis ethylene acrylate phosphate, bis trimethylene acrylate,
Phosphorus ester group-containing ethylene such as bistetramethylene acrylate phosphate, diethylene glycol acrylate phosphate, triethylene glycol acrylate phosphate, polyethylene glycol acrylate phosphate, bisdiethylene glycol acrylate phosphate, bistriethylene glycol acrylate phosphate, bis polyethylene glycol acrylate phosphate and methacrylates corresponding to these And unsaturated unsaturated monomers.

The amount of the photopolymerizable ethylenically unsaturated monomer is
It is 5 to 100 parts by weight, preferably 7 to 80 parts by weight, based on 100 parts by weight of the total amount of the elastomer and the hydrophilic copolymer. When the amount is less than 5 parts by weight, the curing of the photosensitive composition by the active light becomes insufficient, and the strength of the photosensitive rubber plate is reduced. Conversely, if the amount exceeds 100 parts by weight, the strength and solvent resistance of the photosensitive rubber plate decrease.

Examples of the photopolymerization initiator used in the photosensitive composition of the present invention include α-diketones such as diacetyl and benzyl; acyloins such as benzoin and pivaloin; acyloins such as benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether. Ether; polynuclear quinones such as anthraquinone and 1,4-naphthoquinone; and the like. The amount of the photopolymerization initiator is 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the total amount of the elastomer and the hydrophilic copolymer. If the amount is less than 0.1 parts by weight, curing of the photosensitive composition due to actinic light will be insufficient, resulting in a decrease in strength of the photosensitive rubber plate. On the other hand, if it exceeds 10 parts by weight, the photopolymerization rate decreases.

If necessary, the photosensitive composition of the present invention may contain a plasticizer, a storage stabilizer, an ozone resistant agent and the like. Examples of the plasticizer include hydrocarbon oils such as naphthine oil and paraffin oil, polystyrene having a molecular weight of 3000 or less, petroleum resin, polyacrylate, liquid 1,2-polybutadiene, liquid 1,4-polybutadiene, and terminal modified products of these polybutadienes, liquid. Acrylonitrile-
Examples thereof include a butadiene copolymer, a liquid styrene-butadiene copolymer and carboxylated products thereof.

Examples of the storage stabilizer include phenol such as hydroquinone, pyrogallol, p-methoxyphenol, t-butylcatechol, and 2,6-di-t-butyl-p-cresol; benzoquinone, p-toluquinone, p-xyloquinone. Quinone; amines such as phenyl-α-naphthylamine.

The photosensitive composition of the present invention is usually prepared by kneading with a kneader such as a kneader or a roll mill.
The order of kneading is not particularly limited, but in order to obtain a uniform composition, after kneading the hydrophilic copolymer and the elastomer, the photopolymerizable ethylenically unsaturated monomer and the photopolymerization initiator are added. It is good to knead. The hydrophilic copolymer of the present invention is excellent in roll processability because it is well wrapped around a roll and is not sticky.

The photosensitive rubber plate of the present invention has a laminated structure composed of a support and a layer of the photosensitive composition formed on the main surface thereof.

The support usually comprises a flexible film or sheet, and optionally has a release layer or an undercoat layer comprising an adhesive or a primer. The support is not particularly limited as long as it is commonly used in flexographic printing plates, and flexible films such as polyethylene terephthalate film, polypropylene film and polyimide film; natural rubber, synthetic rubber, soft vinyl chloride resin, etc. A flexible sheet made of polyethylene terephthalate, polypropylene, polyimide or the like having an elastic composition backed thereon can be used.

To form a layer of the photosensitive composition on the main surface of the support, a conventionally known method may be adopted. For example,
After the photosensitive composition is molded into a sheet by using a molding machine such as an extruder, a press or a calender, or simultaneously with molding, it is pressure-bonded or adhered to a support, or as a photosensitive composition, chloroform or carbon tetrachloride is used. , Trichloroethane, methyl ethyl ketone, diethyl ketone, benzene,
After dissolving the components of the photosensitive composition in a solvent such as toluene or tetrahydrofuran, pour it into a sheet frame and then evaporate the solvent to form a sheet, or at the same time as forming, press-bonding to a support. Alternatively, it is formed by adhesion.

The photosensitive rubber plate of the present invention is preferably provided with a thin layer of a non-adhesive water-soluble polymer as a coating layer on the layer of the photosensitive composition. The surface of the photosensitive composition layer,
Normally, since the adhesiveness is strong, if the original film is pasted directly on the surface, bubbles will enter between the photosensitive composition and the film, causing turbulent refraction of the active light, and the exposure and curing of the photosensitive layer will not proceed. , As a result, the reproducibility of the relief deteriorates,
The original film adhered to the surface of the photosensitive composition layer may have a problem that it cannot be reused. By providing a thin layer of non-tacky water-soluble polymer, the above problems are eliminated.

The photosensitive rubber plate of the present invention may be further provided with a cover film on the non-adhesive thin layer.
The cover film is made of a flexible resin film, constitutes a protector film layer of the photosensitive composition layer, and optionally also serves as a release layer. Examples of the cover film include polyethylene terephthalate film, polyethylene film, polypropylene film, polystyrene film and the like.

The cover film usually has a thickness of 75 to 20.
It is 0 μm, preferably 100 to 150 μm. 75μ
If it is less than m, the film strength is insufficient and the molded photosensitive rubber plate is easily deformed. Conversely, if it exceeds 200 μm, the film strength is too strong, so that it is difficult to peel off the film from the photosensitive composition layer. In the photosensitive rubber plate of the present invention, a foam may be laminated on the surface of the support opposite to the surface on which the photosensitive composition layer is formed. The printing pressure during flexographic printing can be adjusted by laminating the foam.

Preferred embodiments of the photosensitive composition and the photosensitive rubber plate of the present invention are shown below. (1) 20 to 65 parts by weight of (A) elastomer, (B) 1 to 30 monoethylenically unsaturated monomer containing a phosphoric acid ester group
% By weight, 0.5 to 25% by weight of a diethylenically unsaturated monomer containing a phosphoric acid ester group, 40 to 90% by weight of a conjugated diene monomer and 0 to 58.5% by weight of another monomer are radically copolymerized. 35 to 80 parts by weight of the hydrophilic copolymer (however, the total amount of the elastomer and the hydrophilic copolymer is 100
Parts by weight. ), (C) 5 to 100 parts by weight of a photopolymerizable ethylenically unsaturated monomer, and (D) a photopolymerization initiator 0.1.
A photosensitive composition containing 10 to 10 parts by weight.

(2) The photosensitive composition as described in (1), wherein the elastomer is a block copolymer. (3) At least one of polymer blocks A in which the elastomer is a polymer having an aromatic vinyl monomer as a main constituent unit
And at least one polymer block B comprising a conjugated diene as a main constituent unit and a conjugated diene polymer having a vinyl bond content of the conjugated diene unit portion of 10 to 70%.
The photosensitive composition according to (1), which is a block copolymer having a number of

(4) The block copolymer comprises a polymer block A and a polymer block B in a weight ratio of 5/95 to 95 /.
(5) The photosensitive composition as described in (3) above. (5) The weight average molecular weight of the entire block copolymer is 8.0.
It is 00-2,000,000, The photosensitive composition in any one of (2)-(4) characterized by the above-mentioned. (6) The block copolymer is polystyrene block A
And a polybutadiene block B or a polyisoprene block B, which is represented by the general formula A-B-A. (2) to (5) .

(7) The block copolymer is composed of a polystyrene block A and a polybutadiene block B or a polyisoprene block B and is represented by the general formula ABA. The weight ratio with the combined block B is 5/95 to 95/5, and the weight average molecular weight of the entire block copolymer is 8,000 to 2,000.
It is 10,000, The photosensitive composition in any one of (2)-(6) characterized by the above-mentioned.

(8) The photosensitive composition according to any one of (1) to (7), wherein the hydrophilic copolymer has a gel content of 50 to 100% in a tetrahydrofuran solvent. (9) The phosphoric acid ester group-containing monoethylenically unsaturated monomer has the following formula (1)

[0070]

[Chemical 6]

(Wherein R ¹ is hydrogen or a methyl group, R ² and R ³ are each independently hydrogen or an alkyl group having preferably 1 to 8 carbon atoms, and m and n
Are each independently an integer of 1 to 20. ) The photosensitive composition according to any one of (1) to (8), which is a phosphoric acid ester group-containing monoacrylate or monomethacrylate.

(10) The photosensitizer according to (9), wherein the phosphoric acid ester group-containing monoacrylate or methacrylate represented by the formula (1) is ethylene phosphate monoacrylate, propylene monoacrylate phosphate or a methacrylate corresponding thereto. Sex composition.

(11) The phosphoric acid ester group-containing diethylenically unsaturated monomer has the following formula (2)

[0074]

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(In the formula, R ⁴ and R ⁵ are each independently hydrogen or a methyl group, and R ⁶ , R ⁷ , R ⁸ and R ⁹ are each independently hydrogen or preferably an alkyl group having 1 to 8 carbon atoms. Group, and k, l, m and n are each independently an integer of 1 to 20.) The phosphoric acid ester group-containing bisacrylate or bismethacrylate according to any one of (1) to (18). The photosensitive composition of.

(12) The photosensitive composition according to (11), wherein the bisacrylate or bismethacrylate containing a phosphate ester group is bisethylene acrylate phosphate, bispropylene acrylate phosphate or a methacrylate corresponding thereto. (13) The phosphoric acid ester group-containing monoethylenically unsaturated monomer and the phosphoric acid ester group-containing diethylenically unsaturated monomer have a weight ratio of 90/10 to 20/80 (1) The photosensitive composition according to any one of to (12).

(14) The total amount of the phosphoric acid ester group-containing monoethylenically unsaturated monomer and the phosphoric acid ester group-containing diethylenically unsaturated monomer is the total amount of all monomers used for obtaining the hydrophilic copolymer. It is 5 to 30.5 weight% based on a weight, The photosensitive composition in any one of (1)-(13) characterized by the above-mentioned. (15) (1) to (1) formed on the support and its main surface
A photosensitive rubber plate having a laminated structure comprising a layer of the photosensitive composition according to any one of (14).

[0078]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. In addition, parts and% in Examples and Comparative Examples
Is by weight unless otherwise specified.

The photosensitive composition and the photosensitive rubber plate were evaluated according to the following test methods. [Washing speed] A photosensitive rubber plate was cut into a size of 30 mm × 30 mm to obtain 6 pieces, and the polyethylene terephthalate film on one side of the pieces was peeled off, and a developing machine for a photosensitive flexo plate (JEOL Seiki, JOW -A2-SS type), coconut oil fatty acid diethanolamide 2 at 50 ° C.
% Aqueous solution for 3 minutes, 6 minutes, 9 minutes, 12 minutes and 15 minutes, respectively.
Development for 18 minutes. Next, each developed piece was rinsed with water and dried at 70 ° C. for 20 minutes. From the difference between the thickness of the small piece before development and the thickness of the small piece after development, the amount of change in the thickness per unit time was obtained and used as the development speed.

[Processability] The photosensitive composition was treated at 80 to 120 ° C.
The workability was evaluated by judging the winding state when kneading with the 8 inch roll according to the following criteria. A: Good roll wrapping and good dimensional stability. B: Roll winding is good, but dimensional stability is slightly insufficient. C: It is difficult to process because it is not wrapped around the roll or sticky.

Example 1 An autoclave was charged with 200 parts of water, then 60 parts of butadiene, 18 parts of ethyl acrylate, 7.6 parts of ethylene glycol phosphate, 3.9 parts of bisethylene methacrylate phosphate, 10 parts of styrene, ethylene glycol dimethacrylate. 0.5 parts, 4 parts of sodium dodecylbenzenesulfonate, 0.3 parts of potassium persulfate and 0.4 parts of t-dodecyl mercaptan are added and heated to 50 ° C. to start the emulsion polymerization reaction, and the polymerization conversion rate is 95. When the amount reached 100%, a terminating agent was added to terminate the reaction, followed by cooling with water to obtain a polymer emulsion. Lauryl diethanolamine was added to this emulsion for coagulation, and the obtained crumbs were separated and vacuum dried at 60 ° C. to obtain a hydrophilic copolymer having a gel content of 92%.

55 parts of the hydrophilic copolymer, a block copolymer (styrene / butadiene weight ratio = 20/80 polystyrene-polybutadiene-polystyrene block copolymer, vinyl bond content 32%, weight average molecular weight 150,0)
00) 45 parts, liquid polybutadiene (Nisso PB, B1000 manufactured by Nippon Soda) 50 parts and 2,6-di-t-butyl-p-cresol 0.2 part using a kneader.
After kneading at 0 ° C. until uniform, the kneader temperature is reduced to 12
The temperature was lowered to 0 ° C., 15 parts of 1,9-nonanediol dimethacrylate, 1 part of benzoin methyl ether and 0.02 part of methylhydroquinone were added and further kneaded to obtain a photosensitive composition.

This photosensitive composition was provided with a spacer thickness of 3.0.
mm, put in a frame mold with an open top and bottom, cover the top and bottom of the opening of the frame mold with a polyester film having a thickness of 0.1 mm, and use a press machine at 110 to 130 ° C., 150 k
After heating and pressing with gf, the mixture was cooled to obtain a photosensitive rubber plate having a total thickness of 3.0 mm. The evaluation results of this photosensitive rubber plate are shown in Table 1.

Examples 2-4 and Comparative Examples 1-2 A hydrophilic copolymer, a photosensitive composition and a photosensitive rubber plate were obtained in the same manner as in Example 1 except that the formulations shown in Table 1 were changed. . The evaluation results of this photosensitive rubber plate are shown in Table 1.

[0085]

[Table 1]

From Table 1, obtained by polymerizing a monomer composition containing a small amount of a phosphoric acid ester group-containing monoethylenically unsaturated monomer or a small amount of a phosphoric acid ester group-containing diethylenically unsaturated monomer. It can be seen that the composition containing the hydrophilic copolymer does not have good roll winding. On the other hand, a hydrophilic copolymer obtained by polymerizing a monomer composition obtained by combining an appropriate amount of a monoethylenically unsaturated monomer containing a phosphoric acid ester group and a diethylenically unsaturated monomer containing a phosphoric acid ester group. It can be seen that the film has good roll wrapping during kneading and a high developing speed.

Example 5 98 parts of phosphoric acid and 680 parts of hydroxyethyl methacrylate were dissolved in ethanol and reacted at 70 ° C. for 5 hours in a nitrogen atmosphere, water was added, and the mixture was further reacted for 5 hours to give ethylene glycol phosphate. A mixture containing bisethylene methacrylate phosphate was obtained. As a result of analysis of this mixture using a nuclear magnetic resonance apparatus, the weight ratio of ethylene phosphate phosphate and bisethylene methacrylate phosphate was 66/34.

The total amount of ethylene phosphate and bisethylene methacrylate phosphate in this mixture was 1
1.5 parts by weight of the mixture, 60 parts by weight of butadiene, 18 parts by weight of ethyl acrylate, 10 parts by weight of styrene, 0.5 part of ethylene glycol dimethacrylate, 4 parts by weight of sodium dodecylbenzenesulfonate, 0 parts of potassium persulfate. 0.3 parts by weight and 0.4 parts by weight of t-dodecyl mercaptan were added to an autoclave charged with 200 parts by weight of water and heated to 50 ° C. to start an emulsion polymerization reaction, and a polymerization conversion rate became 96%. When the temperature reached, a termination agent was added to terminate the reaction, followed by cooling with water to obtain a polymer emulsion. Lauryl diethanolamine was added to this emulsion for coagulation, and the obtained crumbs were separated and vacuum dried at 60 ° C. to obtain a hydrophilic copolymer having a gel content of 94%.

Using this hydrophilic copolymer, a photosensitive composition and a photosensitive rubber plate were obtained in the same manner as in Example 1.
The developing speed was 0.18 mm / min, and the workability was A.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08F 290/06 MRS C08F 290/06 MRS C08L 43/00 LKA C08L 43/00 LKA 47/00 LKJ 47 / 00 LKJ G03F 7/00 502 G03F 7/00 502 7/012 511 7/012 511 7/027 502 7/027 502 7/033 7/033

Claims (4)

[Claims] (1) 1 to 30% by weight of a monoethylenically unsaturated monomer containing phosphorus, boron or sulfur, (2)
0.5 to 25% by weight of diethylenically unsaturated monomer containing phosphorus, boron or sulfur, (3) conjugated diene monomer 40
~ 90 wt% and other monomers 0-58.5 wt%
A hydrophilic copolymer obtained by radical copolymerization. 2. (A) 20 to 65 parts by weight of an elastomer,
(B) 35 to 80 parts by weight of the hydrophilic polymer according to claim 1 (however, the total amount of the elastomer and the hydrophilic copolymer is 1
00 parts by weight. ), (C) 5 to 100 parts by weight of a photopolymerizable ethylenically unsaturated monomer and (D) a photopolymerization initiator in an amount of 0.1 to 10 parts by weight. 3. A photosensitive rubber plate having a laminated structure comprising a support and a layer of the photosensitive composition according to claim 2 formed on the main surface of the support. 4. An oxo acid containing phosphorus, boron or sulfur or a salt thereof is reacted with a hydroxyl group-containing ethylenically unsaturated monomer or a corresponding alkoxide to form an ester,
5 to 30.5% by weight of the obtained esterified product, 40 to 90% by weight of a conjugated diene monomer, and 0 to 5 other monomers
A method for producing a hydrophilic copolymer, which comprises radical copolymerizing 8.5% by weight.