JPH05216225A - Photosensitive composition for flexographic printing plate - Google Patents

Abstract

PURPOSE:To enhance easiness in manufacture, physical properties, resistance to solvents, and the like by incorporating a composite rubber obtained by reaction of a specified urethane-modified acrylate with an elastomer, a specified polymerizable compound, and a photoinitiator. CONSTITUTION:Hundred pts.wt. of this photosensitive composition comprises 5-98 pts.wt. of the composite rubber obtained by reaction of the diene type urethane-modified acrylate represented by formula I, with the elastomer and having a gel fraction of <=0.5%, 1-80 pts.wt. of the other elastomer, 1-50 pts.wt. of the polymerizable compound having a photopolymerizable group, and 0.1-20 pts.wt. of the photopolymerization initiator. In formula I, R is 2-8 C alkylene or the like; R1 is H or methyl; each of R2 and R3 is the residue of a diisocyanate compound freed of isocyanate groups: R4 is a group of formula II; R5 is 2-8C alkylene or the like; each of R6 and R7 is H or methyl or the residue freed of OH of a divalent alcohol combined with an acryloyloxy group or the like; and X is the residue freed of OH of a diene type liquid rubber having OH. A support is coated with this composition in a thickness of 0.2-20mm.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a photosensitive composition for flexographic printing plates and a flexographic printing plate obtained therefrom.

[0002]

2. Description of the Related Art As a flexo plate material needs flexibility as its name implies, a rubber component is blended with a polymerizable monomer at the same time as a resin composition for the plate material. For example, US Pat. No. 3,674,486 and US Pat.
No. 23,636 and Japanese Patent No. 1040932 disclose a photosensitive flexographic printing plate material containing an elastomeric block copolymer as a rubber component. However, since the elastomer itself does not crosslink upon photocuring, the plate material obtained has poor solvent resistance.

Japanese Patent Application Laid-Open No. 62-165643 and Japanese Patent Application No. 2-208131 propose a method of kneading a photopolymerizable oligomer for improving the crosslinkability of a composition with the above-mentioned elastomer component. .. However, the compatibility between the oligomer and the rubber may be insufficient, and the plate material obtained may become opaque, resulting in poor image reproducibility. Although physical properties and chemical resistance are improved by the cross-linking of oligomers,
The solvent resistance of the obtained plate material is still insufficient. The solvent resistance of the obtained plate material is still insufficient. In particular, when a solvent-based flexo ink having an alcohol content of 60% or less is used, the plate material swells due to the solvent contained, and good print quality may not be obtained in a long run. In addition, there is a practical problem that the relief is rubbed (scratched) and crushed due to contact with the plate material on the upper surface when the plates inside are taken out from the stacked plates when handling the plate material.

[0004]

Therefore, it is easy to produce a flexographic printing plate, and the physical properties of the obtained printing plate are
Especially scratch resistance of plate surface and solvent resistant ink (especially ink resistance of flexo ink with low alcohol solvent content)
There is a demand for a photosensitive composition for a flexographic printing plate having good properties and a flexographic printing plate obtained therefrom.

[0005]

Means for Solving the Problems That is, the present invention provides (1)
(a)

[0006]

[Chemical 3]

A photopolymerization having a gel fraction of 0.5% or less obtained by reacting a photopolymerizable diene urethane-modified acrylate represented by (b) with a diene elastomer having at least one of (b) Tg of 0 ° C. or less. 5 to 98% by weight of a compounded composite rubber (composite elastomer), 1 to 80% by weight of an elastomer other than the component (1) (2), and (3) a polymerizable compound having at least one photopolymerizable group in the molecule. 1 to 50% by weight, and
(4) The present invention relates to a photosensitive composition for flexographic printing plates containing 0.1 to 20% by weight of a photopolymerization initiator.

It is a well-known phenomenon that when a diene compound, particularly rubber or the like, is kneaded at a high temperature, a high pressure and a high shearing force, polymerization and gelation occur. This is generally
In the process of kneading, intermolecular crosslinking occurs due to the reaction between unsaturated bonds due to heat, or the diene compound itself has high shearing force,
Physical molecular cleavage occurs at low temperatures, and radicals are generated by chemical molecular cleavage at high temperatures, and their active sites cause a recombination reaction between molecules, resulting in a new intermolecular crosslink. It is thought that complexation, polymerization and gelation occur, but the mechanism is still unclear.

In the present invention, the general formula-
Photopolymerizable diene urethane-modified acrylate (a) and diene elastomer (b), further liquid rubber (c)
A photopolymerizable composite rubber obtained by reacting
It has been found that (or simply compounded rubber) has extremely excellent manufacturability, image quality, physical properties of plate materials, and chemical resistance as a binder resin for flexographic plate materials.

The compounded rubber shown in the present invention is a compounded rubber having a new function, which is obtained by simply mixing the components (a) and (b) and the component (c) as conventionally used. The flexographic printing plate made of a composition which is not composited has properties that cannot be obtained, and its production is relatively easy.

The characteristics of this rubber compounding reaction are as follows. (1) A photopolymerizable rubber in which a photopolymerizable group is introduced into a polymer rubber molecule can be produced, and (2) the reaction is not in the form of a rubber solution,
Since it is performed without solvent, it is a simple process that does not require the process of dissolution or desolvation, (3) the complexing reaction must be performed while controlling the gelling reaction, (4) the obtained light Since the polymerizable compounded rubber has sufficient photopolymerizability even after the compounding reaction, it has a characteristic of giving a plate excellent in physical properties and chemical properties when used as a flexographic plate material. Point.

Photopolymerizable diene urethane-modified acrylate oligomer (photopolymerizable oligomer) component used in the present invention
(a) is represented by the general formula-. The photopolymerizable oligomer is obtained mainly by reacting a diene liquid rubber having a hydroxyl group, an ethylenically unsaturated monomer having a monovalent hydroxyl group, a dihydric alcohol and a diisocyanate compound. is there.

Examples of the diene liquid rubber having a hydroxyl group include 1,2-polybutadiene having a hydroxyl group in the molecule, 1,4-polybutadiene, 1,2-pentadiene,
There are polyisoprene, chloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer and the like, and these can be used alone or in combination. The number average molecular weight of the polymer of the diene liquid rubber having a hydroxyl group is 1,000 to 10,000, and the hydroxyl value (m) in the molecule is 1 <m ≦ 4. m ≦ 1
In the case of m> 4, the photo-crosslinking density becomes low, and the solid-form maintenance of the photocured product is not satisfied.

Examples of the ethylenically unsaturated monomer having a monovalent hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 2
-Hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polypropylene glycol mono (meth) acrylate and the like, and at least one or more of them can be used.

Examples of the diisocyanate compound include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate,
There are hexamethylene diisocyanate, isophorone diisocyanate, methylene bis (4-cyclohexyl isocyanate), trimethylhexamethylene diisocyanate, etc., and 5 to 190 parts by weight of at least one compound is added to 10 parts by weight of liquid rubber.

Further, the dihydric alcohol has the following general formula; (In the formula, R ₅ represents an alkylene group having 2 to 8 carbon atoms and a polyoxyalkylene group, and R ₆ and R ₇ represent H, CH ₃ , or a (meth) acryloyloxy group or an allyloxy group.)
And a dihydric alcohol having a skeleton of R in the above formula and a dihydric alcohol having a photopolymerizable ethylenically unsaturated group can be used. As the dihydric alcohol of the above formula, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3
-Butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, etc.,
Further, examples of the dihydric alcohol having a photopolymerizable ethylenically unsaturated group include trimethylolpropane monoacrylate, trimethylolpropane monomethacrylate, and glycerol α-monoallyl ether. At least one or more of these dihydric alcohols can be used.

The mixing ratio of the above components is such that when the repeating unit of the urethane bond is n, the valence of the hydroxyl group is m (1
<M ≦ 4) 1 mol of a diene liquid rubber having a molecular weight of 2000 or less, preferably 300 or less, a dihydric alcohol is m × n mol, a diisocyanate compound is m × (n + 1) mol, and a monovalent hydroxyl group is included. M ethylenically unsaturated monomer
It is a mole.

Here, n is the number of repeating units of a urethane bond composed of a diisocyanate compound and a dihydric alcohol having a molecular weight of 2000 or less, which is 1 to 16, preferably 2 to 16
When the number of repeating units is n> 16 or n <1, it is not preferable because the rubber-like property is lost. The portion n means the length of the portion forming a hard segment with respect to the rubber molecular chain (soft segment). The long hard segment is formed by continuous urethane bonds having high polarity and cohesiveness, and causes microscopic phase separation with a rubber molecular chain (soft segment) having low polarity and cohesiveness. Also, dense crosslinks are provided between the photopolymerizable ethylenically unsaturated groups following the hard segment. Therefore, the photopolymerizable diene urethane-modified acrylate used in the present invention, or the photopolymerizable oligomer alone, gives a high-strength, high-extension photocured product by irradiation with an active energy ray.
When a dihydric alcohol containing R ₄ having a molecular weight of 2000 or more is used, phase separation between the hard segment and the soft segment is less likely to occur, and the desired purpose cannot be achieved. Therefore, the molecular weight of the dihydric alcohol containing R ₄ is 2000 or less,
It is particularly preferably 300 or less. Such a dihydric alcohol having a molecular weight of 2000 or less is introduced into the skeleton of the hard segment component.

The photopolymerizable oligomer comprises a hard segment composed of repeating urethane bonds formed from the above formula-and a diisocyanate compound, and X of the above formula-.
Part, that is, a soft segment composed of a skeleton of a diene liquid rubber, and two segments.

The synthesis of the photopolymerizable oligomer will be specifically described. In a properly selected solvent, dibutyltin dilaurate is added to diisocyanate compound [m × (n + 1)] mol.
In the presence of a catalyst such as tin octenoate, triethylamine and triethylenediamine, a dihydric alcohol (m × n) mol having a molecular weight of 2000 or less is added and reacted little by little to obtain a compound having isocyanate groups at both ends. The reaction temperature in this case should be 10 to 120 ° C, preferably 40 to 80 ° C. Then, to this compound, an ethylenically unsaturated monomer (mole) having a monovalent hydroxyl group is gradually added and reacted,
After preparing a compound having an isocyanate group at one end, 1 mol of a diene liquid rubber having a divalent hydroxyl group is gradually added thereto. In this synthetic reaction, hydroquinone, t-butylcatechol, o-dinitrophenol, m-nitrophenol, p-nitrophenol, 2,4-dinitrophenol, 2,4-dinitrophenol, 2,4, One or two or more of thermal polymerization inhibitors such as 6-trinitrophenol, methoquinone, methoxyphenol, p-benzoquinone, phenothiazine, anthraquinone, 2,6-di-t-butyl-p-cresol, etc. 0.05 to 1% by weight may be added, or air may be bubbled during the reaction. Thereby, the photopolymerizable oligomer represented by the above formula-having a rubber skeleton structure and having an acryloyloxy group, a methacryloyloxy group or a mixture thereof can be synthesized.

The diene elastomer (b), in which at least one Tg is 0 ° C. or lower, which is incorporated in the composition for a photosensitive flexographic plate material of the present invention, has a conjugated diene monomer unit in at least 30 molecules in one molecule in the composition. Mol% (preferably at least 40%) and has a molecular weight of 5,000
0 to 1,000,000 (preferably 10,000 to 50)
000), and at least one glass transition temperature is 0
℃ or less (preferably -5 ℃ or less, most preferably -3
0 ° C or lower). When the amount of the conjugated diene monomer unit is small, the elasticity and flexibility of the resulting composition, the image quality and the like are deteriorated. Further, if the molecular weight is small or large, sufficient developability and image quality cannot be obtained. A typical elastomer is, for example, a polymer of a conjugated diene compound and / or a copolymer of a conjugated diene compound and a monoolefin unsaturated compound. These are prepared by polymerization methods known to those skilled in the art.

An elastomer having at least one Tg of 0 ° C. or lower is an elastomer having at least one Tg of 0 ° C. or lower, in which 1) one Tg is contained like a general elastomer. Those having a Tg of 2 or more, one having a Tg of 0 ° C or less and the other having a Tg of 0 ° C or more, such as a thermoplastic elastomer. The Tg of the elastomer varies depending on the measuring method, but is easily determined by the DSC method, the TMA method, the DMA method, the viscoelasticity measuring method, or the like.

Examples of the conjugated diene compound used for preparing the elastomer (b) include butadiene, isoprene and chloroprene, and one or more of them may be used. Examples of the monoolefin unsaturated compound include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, acrylamide, methacrylamide, and acetic acid. Examples thereof include vinyl, acrylic acid ester, and methacrylic acid ester. In the combination of the conjugated diene compound and the monoolefin unsaturated compound, those having a block copolymer structure are desirable.

Specific examples of the diene elastomer (b) in which at least one of Tg is 0 ° C. or lower include butadiene polymer, isoprene polymer, chloroprene polymer, natural rubber, 1,2-polybutadiene rubber, butyl rubber, pentadiene rubber. , Styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-chloroprene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-isoprene copolymer, acrylonitrile-chloroprene copolymer, methyl methacrylate-butadiene copolymer Polymer, methyl methacrylate-isoprene copolymer,
Methyl methacrylate-chloroprene copolymer, methyl acrylate-butadiene copolymer, methyl acrylate-isoprene copolymer, methyl acrylate-chloroprene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-isoprene-styrene Copolymers, acrylonitrile-chloroprene-styrene copolymers, and further diblock copolymers such as polystyrene-polyisoprene, polystyrene-polybutadiene, polyisoprene-polybutadiene, polystyrene-polybutadiene-polystyrene, polystyrene-polyisoprene-polystyrene, polystyrene- Block copolymers such as polyethylene-polystyrene and polystyrene-polyethylene / butylene-polystyrene may be mentioned, and at least one or more of them may be used. It may also be used.

The above two components are compounded with a diene liquid rubber (c), if necessary, and subjected to a complexing reaction under the condition that gelation does not occur. Examples of the diene liquid rubber (c) include polyisoprene, 1,2-polybutadiene, 1,4-polybutadiene, 1,2-pentadiene, ethylene-butadiene copolymer, acrylonitrile-butadiene copolymer, and modified products thereof. Examples include at least one selected from those having a molecular weight of 500 to 20,000 in a liquid state at room temperature.

In the complexing reaction, the gel fraction is controlled to 0.5% or less, preferably 0.2% or less by reacting under the condition that gelation does not occur. The gel fraction is measured by the following method. The compounded rubber is dissolved in an organic solvent such as toluene or xylene, and the mixture is stirred and dissolved for 24 hours. Then, the solution is filtered through a net of about 400 mesh, and the resin that cannot be filtered is collected and thoroughly washed and dried. Then, the gel fraction can be obtained from the ratio of the gelled product to the original rubber. According to the above measuring method, the gel fraction may be substantially zero. According to the present invention, the condition that the complexation occurs but the three-dimensional crosslinking does not occur is merely expressed by the gel fraction, and the case of substantially 0 which is a desirable condition can of course be included. If the gel fraction is greater than 0.5%, it will be difficult to handle when used as a resin for flexographic plate materials, it will be difficult to elute the developer, and the target plate material performance will not be obtained. Cause problems.

Any conditions may be used as long as the gelation does not occur, that is, the gel fraction of the obtained composite is 0.5% or less. For example, it may be carried out at a low temperature for a long time so that the reaction can be controlled. Generally, such conditions can be satisfied by reacting in the presence of an anti-gelling agent at a temperature of 100 to 200 ° C. under a pressure of 5 to 200 kg / cm ² .

Typical examples of the antigelling agent include amines (eg naphthylamine, diphenylamine, phenylenediamine, etc.), quinolines (eg 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, etc.), hydroquinone derivative (eg, 2,5-di (t-amyl) hydroquinone, 2,5-di-t-butylhydroquinone, hydroquinone Monomethyl ether etc.), monophenols (eg 1-oxy-3-methyl-4-isopropylbenzene, 2,6-di-t-butylphenol etc.), bis-, tris-, or triphenols (eg 2 , 2'-Ethylene-bis-4-methyl-6-t-butylphenol), 2,2-methylenebis (4-methyl-)
6-cyclohexylphenol), etc., thiobisphenols (for example, 4,4′-thiobis- (6-t-butyl-3)
-Methylphenol, etc.), hindered phenols, phosphites, nitrosos, aniline points of 40 to 95.
Examples include naphthene-based process oil containing naphthene component at ℃ as a main component, coumarone-indene resin, rosin resin, phenol resin, petroleum-based hydrocarbon resin and the like. These anti-gelling agents are generally known as anti-aging agents, and "Handbook Rubber / Plastic Compounded Chemicals (Latest Version)", Rubber Digest Co., Ltd., March 30, 1989, pp. 68-127. Page and pages 481-484.

While the above raw materials are charged and kneaded to generate frictional heat, and at the same time, a heating device is used to raise the temperature of the internal reactants to 100 to 200 ° C. and the pressure applied to the internal reactants is 5 to 200 kg. While adjusting to / cm ² , at the same time, the machine is set and acted so that the shearing force acts as a high shearing force on the reactant in the action part of the rotary kneading device, and the compounding reaction is performed. The compounding reaction is usually a hot roll,
Pressure kneader, extruder, planetary mixer,
It is performed with a kneading machine such as a Banbury mixer. In order that the applied shear force effectively contributes to kneading and reaction,
A closed kneader is suitable.

Control of temperature and control of internal pressure are the most important reaction conditions. As for the temperature, it is necessary to adopt a kneading method and apparatus in which the content reactant has a uniform temperature distribution. The conjugation reaction is thought to occur mainly by the reaction between the diene bonds between the molecules. The reaction temperature is 110 to 200 ° C, preferably 100 to 180 ° C, more preferably 10
It is 0 to 150 ° C. Below this temperature, the complexing reaction is less likely to occur, and above this temperature, it is difficult to control the complexing reaction, and the required photopolymerizable diene urethane-modified acrylate (a) represented by general formula (a) and Tg are at least In addition to the compounding reaction with one diene elastomer (b) at 0 ° C or less, a crosslinking reaction mainly occurs between the diene elastomer (b) and within the elastomer, and the entire rubber is difficult to handle as a polymer for flexographic plate materials. There is a risk that it will become highly polymerized or that the entire product will gel.

Another control factor is the control of the pressure applied to the internal reactants. Pressure 5 to 200
in kg / cm ^2, preferably it should be carried out 15~200kg / cm ^2, more preferably 30~190kg / cm ² while controlling. Photopolymerizable diene urethane modified acrylate
In order to efficiently react the (a) and the diene elastomer (b), it is necessary to make them uniformly and well compatible with each other and to bring the reaction sites close to each other. However, if these (a) and (b) have different viscosities, or if the compatibility is insufficient, it is difficult to obtain a sufficiently uniform state by the normal kneading method, so the internal pressure increases. A kneader is preferably used.

Sufficient kneading is necessary to increase the reactivity of the complexing of the internal reactants. Below these pressures, the compounding reaction is insufficient and the resulting photopolymerizable compounded rubber is inferior in cross-linking reactivity and physical properties. Further, above these pressures, a gelling reaction other than the required complexing reaction is likely to occur, the temperature distribution in the system becomes non-uniform, and the whole gels. As a polymer for use, it may be difficult to handle or the desired plate material performance may not be obtained.

The degree of reaction of the composite reaction product of the present invention can be confirmed by measuring the molecular weight and viscosity of the obtained rubber.

The molecular weight is measured by dissolving the reaction product in an organic solvent before the complexing reaction and measuring the molecular weight and the molecular weight distribution by gel permeation chromatography (GPC). A peak attributable to the diene elastomer (b) is observed in the photopolymerizable diene urethane modified acrylate (a) and high molecular weight region. On the other hand, after the compounding reaction, the peak of (a) disappears, so that compounding of the oligomer into rubber can be confirmed. It is preferable that the photopolymerizable composite rubber for flexographic printing plate has the peak (a) disappeared and the gel fraction is 0. Of course, in this case, since the rubber after the compounding reaction has photopolymerizability, it is expected that the compounding is easily caused only by the reaction between the diene bonds. In this method, even if the initial gelation of the composite rubber is advanced, the degree of gelation can be easily predicted from the increase in the high molecular weight portion of the composite rubber.

The viscosity is determined by measuring the resin viscosity with a viscometer such as a Mooney viscometer or a flow tester. However, from a practical point of view, as a monitoring method in the complexing reaction, a method of reading a change in current value of the kneading drive section flowing in the kneading machine is preferable.

A mastication accelerator or a peptizing agent may be added to effectively promote the complexing reaction. It is possible to facilitate the complexing reaction by enhancing the effect of mastication to obtain the effect of unraveling. There are peptizers that are effective at both low and high temperatures. For high temperature use, krysyl mercaptan may be added, and for low temperature use, aromatic sulfur compounds such as 2-benzamidothiophenol and sulfide may be added. Further, in order to improve the physical properties and processability of the rubber to facilitate the compounding reaction, a tackifier, for example, an alkylphenol formaldehyde resin and its modified rosin, an alkylphenol acetylene resin, a coumarone indene resin, a xylene formaldehyde resin, Petroleum-based hydrocarbon resins, polybutene, hydrogenated rosins and processed products thereof may be added. Further, in order to enhance the stability of the polymer in the complexing reaction, a p-phenylenediamine compound, a phenol compound, a paraffin wax compound, etc. may be added.

In the present invention, in addition to the above composite rubber, another elastomer (2) is blended as a binder. Such elastomers have a molecular weight of 1000 to 1,000,000,
It is preferably 5000 to 500,000. Furthermore, at the glass transition temperature of those elastomers,
At least one glass transition temperature is -10 ° C or lower, preferably -30 ° C or lower. In addition, from the relationship with the compounded rubber (elastomer) of (1), it is necessary that the compatibility with them is good. The good compatibility includes not only that turbidity does not occur in appearance by mixing, but also that the film has good physical performance when formed into a film. Specific examples of such an elastomer component (2) include butadiene polymer, isoprene polymer, chloroprene polymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-chloroprene copolymer, acrylonitrile-butadiene. Copolymer, acrylonitrile-isoprene copolymer, acrylonitrile-chloroprene copolymer, methyl methacrylate-butadiene copolymer, methyl methacrylate-isoprene copolymer,
Methyl methacrylate-chloroprene copolymer, methyl acrylate-butadiene copolymer, methyl acrylate-isoprene copolymer, methyl acrylate-chloroprene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-isoprene-styrene Copolymers, acrylonitrile-chloroprene-styrene copolymers, diblock copolymers such as polystyrene-polyisoprene, polystyrene-polybutadiene, polyisoprene-polybutadiene, polystyrene-polybutadiene-polystyrene, polystyrene-polyisoprene-
Polystyrene, block copolymers such as polystyrene-polyethylene / butylene-polystyrene, etc., and epichlorohydrin polymers, epichlorohydrin-ethylene oxide copolymers, epichlorohydrin-propylene oxide copolymers, and / or copolymers thereof with acrylic glycidyl ether. Epichlorohydrin rubber,
Examples thereof include polymers containing no conjugated diene hydrocarbon such as chlorinated polyethylene, vinyl chloride copolymer, vinylidene chloride, polypropylene chloride and chlorinated ethylene-propylene rubber.

The composition of the present invention further contains a polymerizable compound (3) having at least one photopolymerizable group (addition-polymerizable group) in the molecule.

Examples of the polymerizable compound (3) having at least one addition-polymerizable group in the molecule include monomers containing a carboxyl group or a sulfone group; for example, (meth) acrylic acid, styrene-p- Sulfonic acid, hydroxyl group-containing monomer; for example, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, allyl alcohol, methallyl alcohol,
N- (4-hydroxyphenyl) acrylamide or N
-(4-hydroxyphenyl) methallylamide, o-, m
-, P-hydroxystyrene, o-, m-, p-hydroxyphenyl-acrylate or -methacrylate, alkyl acrylate or methacrylate; for example, methyl (meth) acrylate, ethyl (meth) acrylate,
n-Butyl (meth) acrylate, propyl (meth) acrylate, acyl (meth) acrylate, cyclohexyl
(Meth) acrylate, octyl acrylate, 2-chloroethyl acrylate, polymerizable amide; for example, acrylamide, methallyl amide, N-methylol acrylamide, N-methylol methacrylamide, N-ethyl acrylamide, N-hexyl acrylamide, N-cyclohexyl. Acrylamide or methacrylamide such as acrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-nitrophenylacrylamide, N-ethyl-N-phenylacrylamide, nitrogen-containing alkyl acrylate or methacrylate; for example, dimethylaminoethyl acrylate, dimethyl Aminoethylmethacrylate, vinyl ethers: For example, ethyl vinyl ether, 2-chloroethyl vinyl ether, hyaluronate B carboxyethyl vinyl ether,
Propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, phenyl vinyl ether, vinyl esters; for example, vinyl acetate, vinyl chloroacetate, vinyl butyrate, vinyl benzoate, styrenes; for example, styrene, α-methylstyrene, methylstyrene, chloromethyl. Styrene, vinyl ketones:
For example, methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, phenyl vinyl ketone, olefins; for example, ethylene, propylene, isobutylene,
Glycidyl (meth) acrylate, polymerizable nitrile: for example, acrylonitrile, methacrylonitrile, N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, zwitterionic monomer; for example, N, N-dimethyl-N- Methacryloxyethyl-N- (3-sulfopropyl) ammonium-betaine, N, N-dimethyl-N
-Methacrylamidopropyl-N- (3-sulfopropyl) -ammonium-betaine, 1- (3-sulfopropyl) -2-vinylpyridinium-betaine, and compounds having a functional group that chemically reacts with any of the above monomers A compound obtained by the reaction; for example, a reaction product monomer of the above-mentioned hydroxyl group-containing monomer and an isocyanate compound, a reaction product monomer of a carboxyl group-containing monomer and a glycidyl group-containing compound, and the like.

Examples of the compound having at least two addition-polymerizable groups include trimethylolpropane di (meth) acrylate and trimethylolpropane tri (meth) acrylate.
Acrylate, divinylbenzene, ethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth)
Acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexadiol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,3
-Butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, glycerol di (meth) acrylate, glycerol allyloxydi (meth) acrylate, trimethylolpropane di (meth) acrylate ,
Trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol tripropoxytri (meth) acrylate, glycerol (poly) propoxytri (meth) acrylate, neopentyl glycol (poly) ethoxydi (meth) acrylate, tri Methylolpropane (poly) ethoxytri (meth)
Acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,1,1-trishydroxymethylethanedi (meth)
Acrylate, 1,1,1-trishydroxymethylethane tri (meth) acrylate, 1,1,1-trishydroxymethylpropane di (meth) acrylate, 1,1,1-trishydroxymethylpropane tri (meth) acrylate, Triallyl dianurate, triallyl isocyanurate, triallyl trimellitate, sialyl terephthalate, diallyl phthalate and the like can be mentioned.

Preferred examples of the above are glycerol tripropoxytri (meth) acrylate, glycerol (poly) propoxytri (meth) acrylate, neopentyl glycol (poly) ethoxydi (meth) acrylate.
Examples thereof include acrylate and trimethylolpropane (poly) ethoxytri (meth) acrylate.

The photopolymerizable initiator (4) is a compound having a function of initiating addition polymerization upon irradiation with light. Examples of such a compound include benzoin ethers (for example,
Benzoin isopropyl ether, benzoin isobutyl ether), benzophenones (for example, benzophenone, methyl-o-benzoinbenzoate, 4,4'-bis (dimethylamino) -benzophenone), xanthones
(For example, xanthone, thioxanthone, 2-chlorothioxanthone), acetophenones (for example, acetophenone, trichloroacetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone), benzyl, 2-ethylanthraquinone, Methylbenzoyl formate, 2-hydroxy-2
-Methylpropionphenone, 2-hydroxy-2-methyl-4'-isopropyl-isopropiophenone, 1
-Hydroxycyclohexyl phenyl ketone etc. are mentioned. These may be used alone or in combination.

The photosensitive resin composition of the present invention may also optionally be added with conventional additives such as 0.001% to 2.0% by heat based on the weight of the total photosensitive resin composition without solvent. A polymerization inhibitor can be included. Suitable polymerization inhibitors include, for example, hydroquinone, hydroquinone monomethyl ether, mono-t-butylhydroquinone, catechol, p-t-butylcatechol, 2,6-di-t-butyl-
p-cresol, benzoquinone, 2,5-diphenyl-p
-Benzoquinone, p-methoxyphenol, t-butylpyrocatechol, pyrogallol, β-naphthol, 2,6
-Di-t-butyl-p-cresol, phenothiazine, pyridine, nitrobenzene, dinitrobenzene, the nitroso dimer inhibitor system described in British Patent 1,453,681, and U.S. Pat. Bis (substituted amino) sulfides disclosed in 981. Other useful polymerization inhibitors include p-toluquinone, chloranil and thiazine dyes such as thionine blue G.
(CI 52025), Methylene Blue B (CI 52025
15) and toluidine blue (CI 52040). The preferred inhibitor is 2,6-di-t-butyl-4.
-Methylphenol and p-methoxyphenol.

The photosensitive resin composition of the present invention is further mixed with an appropriate amount of a well-known compatible antioxidant and / or antiozonant to prevent polymerization inhibition by oxygen and ozone. Can be improved. Antioxidants useful in the present invention include alkylated phenols such as 2,6-di-t-butyl-4-methylphenol, alkylated bisphenols such as 2,2.
-Methylenebis (4-methyl-6-t-butylphenol), 1,3,5-trimethyl-2,4,6-tris- (3,
5-di-t-butyl-4-hydroxybenzyl) benzene, 2-4-hydroxy-3,5-di-t-butylanilino-4,6-bis (n-octylthio) -1,3,5-triazine, Included are polymerized trimethyldihydroquinone and dilauryl thiodipropionate. Antiozonants useful in the present invention include microcrystalline wax and paraffin wax, dibutylthiourea, 1,1,3,3-tetramethyl-2-thiourea, "antithiozonant" AFD.
(A product of Nafton), norbornene, for example, di-5-norbornene-2-methyladipate, di-5-norbornene-2-methylmaleate, di-5-norbornene-2.
-Methyl terephthalate, "Ozone protector" 80
(Product of Reichhold Chemical Co.), N-phenyl-
2-naphthylamine, unsaturated vegetable oils (eg rapeseed oil, linseed oil, safflower oil), polymers and resins (eg ethylene / vinyl acetate copolymer resins, chlorinated polyethylene, chlorosulfonated polyethylene, chlorinated ethylene / Methacrylic acid copolymer, polyurethane, polypentadiene, polybutadiene, furfural derived resin, ethylene / propylene / diene rubber, diethylene glycol ester of rosin and α-methylstyrene /
Vinyltoluene copolymer).

Optionally, the photosensitive resin composition also comprises an immiscible polymer or non-polymeric substance which is essentially transparent at the wavelengths used for exposing the photosensitive resin material and which does not scatter actinic radiation. Organic or inorganic fillers or reinforcing agents such as polystyrene, internal three-dimensional microresin particles
(Micro gel), organophilic silica, bentonite,
Silica, powdered glass, colloidal carbon and various types of dyes and pigments can be included. Such materials are used in various amounts depending on the desired properties of the elastomeric composition. The filler improves the strength of the elastic layer,
It is useful as a tack reducer and also as a colorant.

If desired, a plasticizer having a good compatibility can be used in the photosensitive resin layer to lower the glass transition temperature of the binder and facilitate selective development. The plasticizer must be compatible with the polymer. Among the common plasticizers that can be used are dialkyl phthalates, alkyl phosphates, polyethylene glycols, polyethylene glycol esters and polyethylene glycol ethers.

In the resin photosensitive composition for flexographic printing plate materials of the present invention, the composite rubber (1) is 5 to 98% by weight, preferably 10 to 95% by weight, more preferably 15% by weight.
~ 90% by weight, elastomers (2) 1-8 other than component (1)
0% by weight, preferably 5 to 50% by weight, more preferably 5 to 30% by weight, the polymerizable compound (3) is 1 to 50% by weight,
Preferably 2 to 40% by weight, more preferably 5 to 25% by weight, and the photopolymerization initiator (4) is 0.1 to 20% by weight,
0.1 to 10% by weight, more preferably 0.2 to 5% by weight
(Based on 100% of the total composition). If the compounded rubber (1) is less than the above range, sufficient physical properties of the plate material cannot be obtained and printability cannot be obtained. If it is more than the above range, the developability will be deteriorated. When the content of the elastomer component (2) other than the component (1) is less than 1% by weight, it is difficult to balance the developability and the physical properties of the plate material, and it is difficult to manufacture the plate material. When it is more than 80% by weight, sufficient physical properties of the plate material cannot be obtained and the printability is not satisfied. If the content of the component (3) is less than 1% by weight, sufficient image quality cannot be obtained. If it exceeds 50% by weight, the plate lacks elasticity and is not suitable for flexographic printing. When the amount of the photopolymerization initiator is less than 0.1% by weight, sufficient image quality cannot be obtained and the sensitivity is lowered. If it exceeds 20% by weight, the crosslink density and the hardness of the plate increase, which makes it unsuitable for flexographic printing.

The above-mentioned photosensitive resin composition of the present invention can be used for producing a resin plate for flexographic printing. That is, the flexographic printing resin plate of the present invention, the photosensitive resin composition obtained above in a molten state in a suitable form (e.g., a sheet or blade) by a conventional method, for example, by extrusion molding or calendar molding. 200μ ~ 2 thickness on support material
Obtained by molding to 0 mm. Examples of the supporting material include a plastic plate, a plastic sheet, a rubber sheet, a foamed olefin sheet, a foamed rubber sheet, a foamed urethane sheet, a metal plate and a metal sheet. A resin plate for flexographic printing can be obtained by appropriately applying an adhesive on these supports, if necessary. Usually, a mat layer is formed on these flexographic printing resin plates in order to improve the vacuum adhesion of the negative film during exposure and the peelability of the negative film after exposure. Therefore, as a desirable structure, the above-mentioned photosensitive resin composition of the present invention is formed on a flexible support through an adhesive layer, and a flexible mat is further provided thereon.

In the production of the flexographic printing plate of the present invention, for example, the flexographic printing resin plate obtained as described above is first exposed through a negative film having an appropriate image, and photopolymerization is caused in the exposed portion. To get a latent image. Examples of the light used for the exposure include ultraviolet rays. Then, after exposure, a non-exposed portion is developed with a developer and washed away to obtain a relief image. When this is further dried and post-exposed with ultraviolet rays, the flexographic printing plate of the present invention having excellent image reproducibility, water resistance, rubber elasticity and mechanical strength can be obtained. The flexographic printing plate is particularly suitable for commercial flexographic printing because of its excellent developability and durability. It should be noted that the ozone resistance of the flexographic printing plate produced can also be improved by annealing it at high temperature before use.

[0050]

INDUSTRIAL APPLICABILITY In the present invention, by using a photopolymerizable composite rubber, that is, a composite rubber obtained by a composite reaction of a diene urethane-modified acrylate having a photopolymerizable functional group and a diene rubber, a flexographic plate The physical properties and chemical properties of the material, especially the solvent resistance and the ink resistance of the solvent ink for flexo having a low alcohol content are improved. It is also easy to form a flexographic printing plate material.

[0051]

EXAMPLES The present invention will be described in more detail by way of examples.
The invention is not limited to these examples. Synthesis Example 1 Production of Photopolymerizable Diene Urethane Modified Acrylate A solution of 48.4 g of 2,4-tolylene diisocyanate (hereinafter abbreviated as "TDI") dissolved in 145.2 g of dioxane was placed in a 500 ml reaction vessel and placed in a nitrogen atmosphere. With stirring below, 14.6 g of 1,4-butanediol, 0.2 g of hydroquinone and 0.2 g of triethylenediamine were added to dioxane 4
The solution dissolved in 9.8 g was added dropwise, during which the reaction solution temperature was maintained at 75 to 80 ° C., and the reaction was continued for 2 hours at the same temperature even after the completion of the addition.

Next, 2-hydroxyethyl methacrylate
(Hereinafter abbreviated as "HEMA") 10.8 g dioxane 32.4 g
The solution dissolved in was added to the reactor, and reacted at 75 to 80 ° C. for 2 hours while stirring in a nitrogen atmosphere.

Further, liquid rubber (JSR-HTPB (manufactured by Japan Synthetic Rubber Co., Ltd., average molecular weight 2120, hydroxyl group content 0.9)
3)) A solution prepared by dissolving 100 g of dioxane in 300 g was placed in another 1000 ml reactor, and the above reaction product was added dropwise with stirring under nitrogen. During the dropping, the reaction solution is
Keep the temperature at 80 ° C and react at the same temperature for 6 hours after the dropping.
Absorption of isocyanate group in infrared absorption spectrum (22
After confirming that 50 cm ⁻¹ ) had disappeared, the reaction was terminated.
The reaction solution is light yellow and transparent, and its viscosity is 450 cps (30 ° C BH
Type viscometer).

The reaction solution was gradually dropped into a beaker containing 5400 ml of n-hexane to obtain a white precipitate. After removing the solvent layer by the gradient method, the precipitate was dried in a vacuum dryer for 2 days. After drying, solid urethane acrylate was obtained. The yield of the polymer was 162 g (92% yield). 3300 cm for infrared absorption spectrum measurement
^{-1, 2920cm -1, 1710cm -1,} the specific absorption of 1640cm ^-1 were observed. The number average molecular weight was 3400 in the molecular weight measurement by gel permeation chromatography (GPC).

Synthesis Examples 2 to 4 Production of Photopolymerizable Diene Urethane Modified Acrylate The same operation as in Example 1 was repeated except that the types of the liquid rubber and dihydric alcohol having a molecular weight of 2000 or less used in Synthesis Example 1 were changed. To produce urethane acrylate. The compounding ratio and the physical properties of the obtained urethane acrylate are shown in Table 1. Further, Table 1 also shows a formulation example in which the number n of repeating units of the hard segment is increased. The weight of the liquid rubber used here is 100 g.

[0056]

[Table 1]

Synthesis Example 5 ( Synthesis of compounded rubber) 45 parts of the photopolymerizable diene urethane-modified acrylate obtained in Synthesis Example 1, styrene content 2
45 parts of 3.5% styrene-butadiene rubber, molecular weight 3
000 liquid 1,2-polybutadiene (10 parts) and phenyl-α-naphthylamine (0.1 part) were placed in a pressure kneader and the temperature in the system was kept at 130 ° C to 140 ° C while kneading under pressure for 4 hours. A complexing reaction was performed. During the complexing reaction, the current value flowing through the pressure kneader and the temperature inside the system were continuously monitored. During the complexing reaction, the current value showed a constant value without increase or decrease. Sampling was done at the second hour on the way. The photopolymerizable composite rubber-1 obtained after the composite reaction and the molecular weight distribution of the reaction sample in 2 hours were analyzed by GPC. When the reaction sample was 2 hours, Mn = 25,000, Mw = 105,000, the reaction After that, Mn = 72,000 and Mw = 116,000. A peak due to the diene-based urethane-modified acrylate, which was observed before the start of the complexing reaction, was partially observed at the second hour, but the peak disappeared after the reaction.

Next, 1 part of the composite rubber was taken and dissolved in 19 parts of toluene for 24 hours and then filtered through a 400 mesh screen to measure the gel fraction. 01% and 0.1% after the reaction. Gel fraction = {(filtration residue at 400 mesh) / (sample amount)} × 100% Take 100 parts of the obtained composite rubber and 2 parts of Irgacure (IR-651, manufactured by Ciba Geigy) as a photopolymerization initiator. It was sufficiently kneaded to form a 100 µ film, and photopolymerizability was confirmed.

[0059]

[Table 2]

[0060]

[Table 3]

Synthesis Example 12 A part of the composite elastomer-1 obtained in Synthesis Example-5 was subjected to a composite reaction by raising the compounding temperature by the same method and keeping it at 160 ° C. for 1 hour. A composite elastomer was obtained. The gel fraction of the present elastomer measured by the same method was 1.0%.

Example-1 Photopolymerizable composite elastomer 65 obtained in Synthesis Example-5
Part, polystyrene-polyisoprene-polystyrene block copolymer elastomer (trade name Califlex T
R-1107, manufactured by Ciel) 25 parts, polyethylene glycol diacrylate (obtained from polyethylene glycol having a molecular weight of 200) 4 parts, 1,6 hexanediol diacrylate 2 parts, trimethylolpropane triacrylate 2 parts, photopolymerization initiator As Irgacure 651
(Ciba Geigy) 1.5 parts, Irgacure 184
(Ciba Geigy Co., Ltd.) 0.5 parts, metoquinone 0.1 parts, and di-tert-butyl paracresol 2 parts were charged into a pressure kneader and mixed with stirring to obtain a photosensitive flexo plate material composition.

The obtained mixture was mixed with a double-arm kneader and had a diameter of 35 mm.
A chloroprene adhesive (HIBON 1920L, Hitachi Chemical Co., Ltd.) was extruded into a sheet by a single-screw extruder in advance.
A 2.8 mm-thick photosensitive resin layer was formed on a 130 μ-thick polyester film coated with T). Next, PET coated with a toluol solution of polyamide resin and a coating agent for forming a matting layer consisting of fine silica powder
The films were stacked and the matte layer was transferred to obtain a photosensitive flexographic printing plate.

In order to form a relief on the surface of the photosensitive flexographic printing plate, back exposure is performed from the back of the plate for 4 minutes by an exposure device composed of a 60 W ultraviolet lamp to form a floor, and then an appropriate image is formed. The negative film was brought into vacuum contact and irradiated for 12 minutes this time to perform main exposure. After irradiation, it was developed with a 20 ° C. trichlorethane for 5 minutes using a DuPont elution machine 1215 system to develop a relief 1.2 mm faithful to the negative.
I got a printing plate of.

The shore hardness A of the obtained plate material is 47 degrees, has sufficient elasticity, and is tough, and the alcohol content is 80% or more at a printing speed of 500 feet / minute on a stack type two-color flexographic printing machine. Printing was performed on a 70 μm-thick opalized polyethylene film using the flexo ink of (1). No change was observed on the surface of the printing plate even after printing 200,000 times.

Solvent resistance evaluation In order to examine the solvent resistance of the obtained printing plate, the plate was immersed in hexane and ethyl acetate, left for 6 hours, taken out, and the adhering solvent was removed. When it was determined, it was 82% for hexane and 86% for ethyl acetate.

Next, the alcohol content for the poly film is 6
The surface of the printing plate was printed after printing 10,000 times on a 70 μ thick opalescent polyethylene film using 0% or less of solvent-type flexo ink, but no change was observed. No change was observed on the surface, but a slight thickening was observed in the thin line compared to the initial stage.

Evaluation of physical properties of film A check of practical toughness of the obtained printing plate was conducted.
The coin scratch method was used. It was confirmed that it had good toughness without being scratched at all even after being scratched 5 times.

Comparative Example 1 In Example-1, 29.3 parts of the photopolymerizable diene urethane-modified acrylate obtained in Synthesis Example 1, 29.2 parts of styrene-butadiene rubber having a styrene content of 23.5%, and a molecular weight of 3 were used. A composition for a photosensitive flexographic printing plate material was obtained in the same manner except that a mixture of 6.5 parts of 1,000 liquid 1,2-polybutadiene was used in place of the compounded elastomer of Synthesis Example-5 without compounding reaction. Similarly, a resin layer was formed on a polyester film to obtain a photosensitive flexographic printing plate.

In the same manner, exposure and development were carried out to form a relief to obtain a printing plate. The shore hardness A of the obtained plate material is 45 degrees, and 70 μ using a flexographic ink containing 80% or more of an alcohol component at a printing speed of 500 ft / min.
Printing on thick opalescent polyethylene film
A slight chipping was observed in the fine lines of the printing plate when printing 10,000 times.

A similar solvent resistance test of the obtained printing plate shows that hexane is 160% and ethyl acetate is 100%.
An increase in the weight of the plate material was observed with an organic solvent of 10%. Furthermore,
In a printing test using a solvent-based flexo ink having an alcohol content of 60% or less, a thick relief line was found to thicken after printing 10,000 times, and a good printed matter could not be obtained. Also, the toughness of the plate was similarly tested by the coin scratch method, but scratches were made by scratching 3 out of 5 times.

Comparative Example 2 A composition for a photosensitive flexographic plate material was obtained in the same manner as in Example 1 except that the compounded elastomer obtained in Synthesis Example 12 was used instead. A printing plate was produced.

Similarly, exposure and development were performed to form a relief and a flexographic printing plate was obtained, but the image reproducibility was not good. In particular, the diameters of 250 μm and 750 μm had shallow depths at white points, and they did not have practical performance.

[0074]

[Table 4]

Examples 2 to 4 Compositions for photosensitive flexographic printing plate materials were obtained in the same manner with the formulations shown in Table 3, and printing plates were obtained in the same manner. Both plates had good image quality and printing performance. It also had good performance in a solvent resistance test.

Examples 5 to 8 The photopolymerizable composite elastomer (1) having the same composition as in Example 1 was used instead of Synthesis Example-5, Synthesis Examples-9, -10,-
Using the composite elastomers Nos. 11 and -6, a photosensitive flexographic printing plate composition was obtained in the same manner, and a printing plate was prepared and evaluated. All had good performance.

Continuation of front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location G03F 7/033 (72) Inventor Hisao Sato 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka Japan Paint Co., Ltd. ( 72) Inventor Chitoshi Kawaguchi, 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka, Japan Paint Co., Ltd. (72) Yusuke Ninomiya 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka, Japan Paint (72) Invention Definition of Personnel Affairs 3-4-24 Minami Teshiro Town, Fukuyama City, Hiroshima Prefecture (72) Inventor Toshihiro Fujii 545 Tsunoshita, Daimon Town, Fukuyama City, Hiroshima Prefecture

Claims (7)

[Claims] 1. (1) (a) embedded image A photopolymerizable composite having a gel fraction of 0.5% or less obtained by reacting a photopolymerizable diene urethane-modified acrylate represented by (4) with (b) a diene elastomer in which at least one of Tg is 0 ° C or less. 5 to 98% by weight of rubber, (2) 1 to 80% by weight of an elastomer other than the component (1), (3) 1 to 50% by weight of a polymerizable compound having at least one photopolymerizable group in the molecule, and ( 4) A photosensitive composition for flexographic printing plates containing 0.1 to 20% by weight of a photopolymerization initiator. 2. The reaction between the modified acrylate (a) and the diene elastomer (b) is carried out at a temperature of 100 in the presence of an antigelling agent.
The photosensitive composition according to claim 1, which is carried out in a closed kneader at ˜200 ° C. 3. The photosensitive composition according to claim 1, wherein (c) a diene liquid rubber is added as a third component in the reaction between the modified acrylate (a) and the diene elastomer (b). 4. In the reaction of the modified acrylate (a) with the diene elastomer (b), the modified acrylate (a) is used in an amount of 5 to 90% by weight, and the diene elastomer (b) is used in an amount of 10 to 70%. The photosensitive composition according to claim 2, wherein the amount by weight and the amount of the antigelling agent used are 0.01 to 5% by weight. 5. The amount of the diene liquid rubber (c) used is 1 to 3.
The photosensitive composition according to claim 3, which is 0% by weight. 6. The diene elastomer (b) is natural rubber,
Isoprene rubber, butadiene rubber, styrene butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber,
The photosensitive composition according to claim 1, which is selected from the group consisting of a pentadiene rubber and a block copolymer of styrene and isoprene or butadiene. 7. (1) (a) embedded image A photopolymerizable composite having a gel fraction of 0.5% or less obtained by reacting a photopolymerizable diene urethane-modified acrylate represented by (4) with (b) a diene elastomer in which at least one of Tg is 0 ° C or less. 5 to 98% by weight of rubber, (2) 1 to 80% by weight of an elastomer other than the component (1), (3) 1 to 50% by weight of a polymerizable compound having at least one photopolymerizable group in the molecule, and ( 4) A photosensitive composition for a flexographic printing plate containing 0.1 to 20% by weight of a photopolymerization initiator is formed on a flexible support with an adhesive layer to a thickness of 200 μ to 20 mm. , A photosensitive flexographic printing plate material having a flexible resin mat layer structure thereon.