JPH07114180A - Photosensitive composition, photosensitive rubber plate and production thereof and flexographic printing plate and production thereof - Google Patents

Abstract

PURPOSE:To produce the photosensitive composition soluble in a water-based developer, having good photosensitivity, transparency and workability and giving the cured body excellent in transparency and rich in low temp. elastic strength. CONSTITUTION:This photosensitive composition incorporates (A) 35-80wt.% phosphorus-containing hydrophilic copolymer obtained by copolymerizing the mixture of monomers of (a) 5-30wt.% phosphate group-containing unsatd. monomer, (b) 40-49wt.% conjugated dienes monomer and (c) 0-50wt.% monoolefins unsatd. monomer except (a), (b) 65-20wt.% thermoplastic elastmer ((A)+(B)=100 pts.wt.), (C) 5-300 pts.wt. photo polymerizable ethylenic unsatd. monomer and (D) 0.1-10 pts.wt. photo polymerization initiator, and the subject photosensitive rubber plate and the subject flexographic printing plate are made of this composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive composition, a photosensitive rubber plate and a method for producing the same, a flexographic printing plate and a method for producing the same. More specifically, the present invention relates to a photosensitive composition containing a phosphorus-containing hydrophilic copolymer and a thermoplastic elastomer, a photosensitive rubber plate obtained by laminating it on a support, and a photosensitive rubber plate obtained by using the same. Flexographic printing plates as well as methods for producing them.

[0002]

2. Description of the Related Art Conventionally, as a plate material for flexographic printing,
For example, a rubber casting plate produced by heat-pressing a thermosetting resin to a master plate obtained by etching a metal plate to form a mother mold, and then pouring rubber into the mother mold and pressurizing it, styrene-butadiene rubber, Known is a photosensitive resin plate obtained by plate-making a photosensitive resin composition containing a synthetic rubber such as acrylonitrile-butadiene rubber as a main component and a photopolymerizable monomer having a terminal ethylenic double bond added thereto. There is.

However, the former rubber casting plate has drawbacks that it takes a long time to make a plate, the manufacturing cost is high, and the image reproducibility of the plate itself is poor. On the other hand, the latter photosensitive resin plate mainly composed of synthetic rubber is inferior in solvent resistance, abrasion resistance and durability, and as a developing solution at the time of plate making,
For example, since a halogenated hydrocarbon such as 1,1,1-trichloroethane is used, there are drawbacks such as deterioration of working environment.

In recent years, in order to improve such drawbacks,
Various photosensitive resin compositions for flexographic printing plates having water developability have been proposed (JP-A-54-110287 and JP-A-61-22339). However,
These compositions are not practical because they require the use of a special developer composed of water / alcohol / alkali for the development treatment and require heating because the developing speed is extremely slow. .

Further, a copolymer of a conjugated diolefin, an α, β-ethylenically unsaturated carboxylic acid and a monoolefin unsaturated monomer optionally used, a photopolymerizable unsaturated monomer and a photopolymerization A photosensitive resin composition containing an initiator has been proposed (Japanese Patent Publication No. 59-29849). However, although this composition has some advantages over the previous ones, it is not always satisfactory in terms of processability, transparency of the cured product, elasticity at low temperature, etc., especially in cold regions. Had a problem that the printing plate obtained by using this composition had an increased hardness and could not be used as a flexographic printing plate.

In order to solve such a problem, the present inventors have previously proposed that a conjugated diolefin, a (meth) acrylate having an acidic functional group, and optionally a monoolefin-based unsaturated monomer or a polyolefin. A photosensitive resin composition comprising a copolymer with a functional vinyl monomer, a photopolymerizable unsaturated monomer, and a photopolymerization initiator has been proposed (Japanese Patent Laid-Open No. 4-204).
No. 67041). However, although this photosensitive composition is improved in transparency and elasticity at low temperature, it is referred to as (1) washing out at the time of printing plate formation with an alkaline aqueous solution (dissolution / removal of an unexposed portion during development). ), And (2) the strength of the plate sufficient to prevent cracks during bending, etc., were not always satisfactory.

In recent years, from the viewpoint of preventing air pollution, water-based inks have been used instead of solvent-based inks in flexographic printing, but the flexographic plate used at this time does not swell with water-based inks. Is required. However, in a photosensitive composition using an alkaline aqueous solution as a developing solution, it has been difficult to achieve both the alkaline developing property and the water-resistant ink resistance of the flexographic printing plate obtained.

As a countermeasure against this, the present inventors have used a monoolefin unsaturated monomer unit such as an acrylate compound as a main skeleton, and a phosphate ester group-containing unsaturated monomer unit,
Furthermore, if desired, a photosensitive composition for water development containing a phosphorus-containing hydrophilic copolymer containing a polyfunctional vinyl monomer unit, a photopolymerizable unsaturated monomer and a photopolymerization initiator. Was developed. However, although this photosensitive composition was improved in washability (efficiency of dissolution / removal of unexposed areas during development), the obtained printing plate was not yet strong enough, and easily swelled with an aqueous ink. , The above problems have not been solved.

Further, the surface of the photosensitive composition generally has strong adhesiveness, and therefore, a negative film or a positive film (hereinafter, these may be collectively referred to as "original film") is directly attached to the surface. , And air bubbles enter between the original film and the exposed active light are diffusely refracted, resulting in insufficient exposure of the photosensitive layer, resulting in
There is a problem that the reproducibility of the relief is deteriorated and the original image film adhered to the surface of the photosensitive layer cannot be reused.

As a method for solving such a problem, a thin film called a slip film (coating material) is coated on the surface of the photosensitive composition. As such a coating material, polyamide or Cellulose derivatives and the like have been used conventionally. This coating material needs to be dissolved and removed together therewith when removing the unexposed portion of the photosensitive layer after exposure. However, the coating material that has been conventionally used can be easily removed with a halogenated hydrocarbon developer. Although it can be dissolved and removed, it is difficult to apply it to a photosensitive resin plate using an aqueous developer because it is insoluble in water or sparingly soluble in water.

By the way, conventionally, for forming a sheet of a photosensitive composition, for example, a method of kneading in a mixing mill and then treating with a hot press and a calendar to form a sheet, or a solution of the composition in a mold is used. A solvent casting method in which the solvent is removed by heating after pouring is adopted. However, in the former method, the smoothness of the sheet surface and the thickness accuracy were insufficient. Further, the latter method has problems that air bubbles remain in the sheet and the uniformity of the composition is impaired.

Recently, an extruder has been used for calendering the sheet of the composition, but in this method, the melting / kneading temperature in the extruder and the sheet forming temperature are high. There is a problem that a so-called neck-in phenomenon occurs in which the sheet width is narrower than the die width. Also, since the so-called lip molding cannot be performed because the molding temperature is high, it is unavoidable to form a pool (bank) of the composition in a calender roll before molding, but as a result, shrinkage occurs after sheet molding. There was a problem such as waking up.

[0013]

Accordingly, one of the objects of the present invention is that it is soluble in an aqueous developer, has good photosensitivity, transparency and processability, and when it is cured by exposure. Another object of the present invention is to provide a photosensitive composition which is excellent in transparency and gives a cured product having a high elasticity at a low temperature. A second object of the present invention is to provide a photosensitive rubber plate which is prevented from sticking to an original film and can be easily developed with an aqueous developer.

Further, a third object of the present invention is to provide a method for producing a photosensitive rubber plate which does not cause a neck-in phenomenon or shrinkage after sheet molding and is excellent in surface smoothness and thickness accuracy. It is in. Further, a fourth object of the present invention is to improve the plate strength and water-resistant ink resistance of the flexographic printing plate which affects the relief image reproducibility, and the flexographic printing plate which can be suitably used for actual flexographic printing and its production. To provide a method.

[0015]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have obtained (1) a wash-out property as a photosensitive composition developable with an aqueous developer. In order to make the strength of the printing plate compatible, it is effective to make the main skeleton of the copolymer constituting the photosensitive composition hydrophobic and to introduce a hydrophilic group into it, (2) As a hydrophilic group Use of a phosphoric acid ester group results in excellent processability and washability of the photosensitive composition and excellent water resistance of the flexographic printing plate. (3) Block copolymer having the above-mentioned hydrophilic copolymer and pseudo-crosslinking property When used together, a flexographic printing plate having a practical plate strength can be obtained without impairing other required properties. (4) By using the above hydrophilic copolymer, sheet formation of a photosensitive composition Lowering process temperature Possible, this by the temperature drop is improved neck-in phenomenon, it was found that the lip molding is made possible.

The present invention has been completed as a result of further research based on such findings. That is, according to the present invention: (A) (a) Phosphate ester group-containing unsaturated monomer 5
Copolymerization of a monomer mixture comprising 30% by weight, (b) 40 to 90% by weight of a conjugated diene monomer, and (c) 0 to 50% by weight of a monoolefinic unsaturated monomer other than (a). 35-80 parts by weight of the phosphorus-containing hydrophilic copolymer thus obtained,
(B) 65 to 20 parts by weight of the thermoplastic elastomer (however,
The total of (A) and (B) is 100 parts by weight. ),
(C) 5 to 300 parts by weight of a photopolymerizable ethylenically unsaturated monomer based on 100 parts by weight of (A) and (B) in total,
And (D) a photosensitive composition containing 0.1 to 10 parts by weight of a photopolymerization initiator based on 100 parts by weight of (A) and (B) in total,

2. 2. A photosensitive rubber plate which is a laminate composed of a support and the above-mentioned photosensitive composition layers formed on the main surface thereof. 3. A method for producing a photosensitive rubber plate, which comprises kneading the above photosensitive composition, extruding it through a die, and then laminating it on a support by calendering. 4. A method for producing a flexographic printing plate, which comprises exposing the above-mentioned photosensitive rubber plate to light and then removing the unexposed portion with an aqueous developer. A flexographic printing plate obtained by this method is provided.

The present invention will be described in detail below. The photosensitive composition of the present invention comprises a phosphorus-containing hydrophilic copolymer as the component (A), a thermoplastic elastomer as the component (B), and (C).
It is necessary to contain a photopolymerizable unsaturated monomer as a component and a photopolymerization initiator as a component (D).

The phosphorus-containing hydrophilic copolymer (A) used in the present invention comprises (a) 5 to 30% by weight of a phosphoric acid ester group-containing unsaturated monomer and (b) a conjugated diene monomer 40 to 9
0% by weight, (c) 0 to 50% by weight of a monoolefinic unsaturated monomer other than (a), and (d) a monomer mixture comprising 10% by weight or less of a polyfunctional vinyl monomer, if desired. Obtained by copolymerization.

The phosphoric acid ester group contained in the monomer of the component (a) is incorporated into the unexposed portion of the photosensitive composition in water when the photosensitive rubber plate of the present invention is exposed and then developed with an aqueous alkaline solution. It serves to promote dispersion. It is considered that this is because the phosphoric acid moiety in the phosphoric acid ester group is brought into contact with the alkaline aqueous solution to swell the photosensitive composition. Further, the swelling of the flexographic printing plate with the water-based ink is less than that in the case of using other acidic and hydrophilic functional groups. It is presumed that this is due to the action of the ester moiety in the functional group.

The phosphoric acid ester group-containing unsaturated monomer used in the present invention is represented by the general formula [I]

[Chemical 1] A phosphoric acid monoester or a phosphoric acid diester represented by can be used (in the formula, R ¹ may have a hydrogen atom or a methyl group, and R ² may have a substituent such as a hydrogen atom, a methyl group, or a halomethyl group). A lower alkyl group having 3 or less carbon atoms, m is an integer of 1 to 23, and n is 1 or 2.).

Specific examples of the phosphoric acid ester group-containing unsaturated monomer represented by the above-mentioned general formula [I] include phosphoric acid ethylene acrylate, phosphoric acid trimethylene acrylate, phosphoric acid propylene acrylate, phosphoric acid tetramethylene acrylate and phosphoric acid (bis). Ethylene acrylate, phosphoric acid (bis)
Trimethylene acrylate, phosphoric acid (bis) tetramethylene acrylate, phosphoric acid diethylene glycol acrylate, phosphoric acid triethylene glycol acrylate, phosphoric acid polyethylene glycol acrylate, phosphoric acid (bis) diethylene glycol acrylate, phosphoric acid (bis) triethylene glycol acrylate, phosphoric acid (bis) polyethylene glycol acrylate And methacrylates corresponding thereto; and the like. These may be used alone or in combination of two or more.

Of these, ethylene phosphate acrylate, propylene acrylate phosphate and methacrylates corresponding thereto are preferable, and ethylene phosphate methacrylate is more preferable. The unsaturated monomer containing a phosphoric acid ester group as the component (a) is used in a proportion of 5 to 30% by weight, preferably 5 to 20% by weight, based on the total amount of the monomer mixture. If this amount is less than 5% by weight, washability of the photosensitive composition obtained by the present invention is deteriorated. On the other hand, when it exceeds 30% by weight, the washability becomes good, but the processability of the photosensitive composition and the water-resistant ink resistance of the flexographic printing plate tend to decrease.

The conjugated diene monomer as the component (b) is the main skeleton of the copolymer used in the present invention and is hydrophobic. By using this monomer, a flexographic printing plate having improved elasticity and water-resistant ink resistance can be obtained. The mechanism is considered to be because the copolymer obtained by using this monomer is hydrophobic and thus is less susceptible to the influence of the developer and the aqueous ink.

Examples of the conjugated diene-based monomer used in the present invention include 1,3-butadiene, isoprene, chloroprene, and 1,3-pentadiene. These may be used alone. You may use it in combination of 2 or more type. Among the above conjugated dienes, 1,3-butadiene and isoprene are preferable. The conjugated diene-based monomer as the component (b) is 40 to 40% based on the total amount of the monomer mixture.
90% by weight, preferably 50 to 80% by weight. When this amount exceeds 90% by weight, the elasticity of the flexographic printing plate obtained is improved, but since the monomer itself is hydrophobic, the washability of the photosensitive composition and the hydrophilicity of the obtained flexographic printing plate are improved. Is reduced. On the other hand, if it is less than 40% by weight, the flexographic printing plate has insufficient strength.

Next, as the monoolefin unsaturated monomer of the component (c), for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, dodecyl acrylate, methoxyethyl. Acrylic esters such as acrylate, ethoxyethyl acrylate, cyanoethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, and corresponding methacrylic acid esters; for example, styrene,
Aromatic vinyl monomers such as α-methylstyrene; α, β-ethylenically unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile; ethylidene norbornene,
Non-conjugated dienes such as propenyl norbornene and dicyclopentadiene; vinyl chloride; and the like. These may be used, or two or more kinds may be used in combination.

These monoolefin unsaturated monomers are used in an amount of 0 to 50% by weight, preferably 10 to 40% by weight, based on the total amount of the monomer mixture, in view of the balance with other physical properties. From desirable. If the amount used is too large, the amounts of the phosphate ester group-containing unsaturated monomer and the conjugated diene-based monomer in the copolymer (A) decrease, and the developability of the photosensitive composition and the water-resistant ink of the printing plate obtained are obtained. Sex decreases.

In the present invention, in order to enhance the transparency and processability of the photosensitive composition and to impart strength and elasticity to the flexographic printing plate, a polyfunctional vinyl monomer is optionally used as the component (d). You may use. This monomer is a compound containing two or more polymerizable unsaturated bonds in one molecule and having an equivalent reactivity, and examples thereof include ethylene glycol diacrylate and trimethylol. Acrylic acid esters and methacrylic acid esters of polyhydric alcohols such as propane triacrylate and propylene glycol diacrylate; polyfunctional aromatic vinyl monomers such as divinylbenzene and trivinylbenzene; among others, ethylene glycol Dimethacrylate and divinylbenzene are preferred. These polyfunctional vinyl monomers may be used alone or in combination of two or more. These monomers are preferably used in a proportion of 10% by weight or less based on the total amount of the monomer mixture.

The method for producing the above-mentioned copolymer is not particularly limited, but usually it can be produced by emulsion copolymerization. The molecular weight of the copolymer is not particularly limited, but is usually in the range of 10,000 to 500,000, preferably 20 in terms of number average molecular weight, from the viewpoint of strength and processability of the resulting photosensitive composition. It is in the range of 1,000 to 200,000. The method for controlling the molecular weight is not particularly limited, but usually
A molecular weight regulator is used, and the amount to be used may be appropriately selected depending on the kind of the molecular weight regulator and the desired molecular weight. When mercaptan is used as the molecular weight modifier, it is preferably selected in the range of 0.1 to 5 parts by weight per 100 parts by weight of the total monomer mixture.

The blending amount of the component (A) is 35 to 80 parts by weight, preferably 40 to 70 parts by weight, based on 100 parts by weight of the total of the components (A) and (B). Therefore,
The blending amount of the component (B) is 65 to 20 parts by weight, preferably 60 to 30 parts by weight, based on 100 parts by weight of the total of the components (A) and (B). When the amount of the component (A) is less than 35 parts by weight, the hydrophilicity and washability of the photosensitive composition are not improved, and when it exceeds 80 parts by weight, the washability of the photosensitive composition is good, but the photosensitive composition And the water-resistant ink resistance of the flexographic printing plate are deteriorated.

In the photosensitive composition of the present invention, the thermoplastic elastomer used as the component (B) may be a so-called crystalline polymer having both a crystalline phase and an amorphous phase in the same molecule, and is a thermoplastic elastomer. Examples thereof include block copolymers, crystalline 1,2-polybutadiene, polyurethane elastomers and polyester elastomers.

Of these, a thermoplastic elastomer block copolymer is preferred. The thermoplastic elastomer block copolymer which can be preferably used in the present invention includes at least two thermoplastic non-elastomeric polymer blocks and a thermoplastic elastomer in which these non-elastomeric polymer blocks are bonded via an elastomer block. Block copolymer, wherein the thermoplastic non-elastomeric polymer block is represented by X and the elastomer block is represented by Y, at least one X-Y-X or X-Y-Z-Y
Having a unit represented by -X, for example, a general formula (X-Y) _n- X, (Y-X) _{n + 1-} Y, (X-Y).
_{n + 1} , (X−Y) _m −Z. However, Z
Represents a coupling agent residue, n is 1 to 10 and m is 2
It is an integer of 7.

The ratio of the thermoplastic non-elastomeric polymer block X to the elastomer block Y is within the range in which the block copolymer becomes an elastomer, that is, the ratio of the thermoplastic non-elastomeric polymer block X in the copolymer. It is desirable to be in the range of 5 to 50% by weight, preferably 10 to 40% by weight. If the proportion of the polymer block X exceeds 50% by weight, the block copolymer is unlikely to be an elastomer, and it is difficult to provide the photosensitive composition and the flexographic printing plate with sufficient rubber elasticity. On the other hand, 5% by weight
If less than, the block copolymer becomes rubbery at room temperature,
The flexographic printing plate tends to shrink, resulting in lack of dimensional stability.

The thermoplastic non-elastomeric block copolymer X which can be particularly preferably used in the present invention has a number average molecular weight of 2,000 to 100,000, preferably 5,0.
The glass transition temperature is 25 to 50 ° C., preferably 50 ° C. or more, while the elastomeric block has a number average molecular weight of 25,000 to
1,000,000, preferably 30,000-30
And the glass transition temperature is 10 ° C or lower, preferably 0 ° C or lower.

The thermoplastic non-elastomeric block copolymer which can be particularly preferably used in the present invention is, for example, one or more polymers or copolymers of monovinyl aromatic monomers such as styrene, α-methylstyrene and ethylstyrene. It is a combination or a copolymer of these monomers with a copolymerizable monomer. On the other hand, the elastomeric block Y means, for example, a homopolymer or copolymer of a conjugated diene such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene, or a copolymer thereof. It is a copolymer of a monomer and a copolymerizable monomer.

Specific examples of such a thermoplastic elastomer block copolymer include polystyrene-polybutadiene-polystyrene, polystyrene-polyisoprene-polystyrene, poly (α-methylstyrene) -polybutadiene-poly (α-methylstyrene). , (Polystyrene-polybutadiene) ₄ Si, (polystyrene-polyisoprene) ₄ Si, hydrogenated products thereof, and maleic acid modified products thereof. Among these, those in which the thermoplastic non-elastomer block X is polystyrene and the elastomer polymer block Y is polybutadiene or polyisoprene are particularly preferably used. The thermoplastic elastomer as the component (B) may be used alone or in combination of two or more.

By using this thermoplastic elastomer, the strength of the sheet of the photosensitive rubber plate of the present invention before and after exposure is improved. It is presumed that the strength is improved by the reinforcing effect of the pseudo-crosslinked structure in the case of the block copolymer and by the reinforcing effect of the constrained structure of the crystalline phase in the case of the crystalline polymer. Even if only an elastomer other than the above-mentioned thermoplastic elastomer is used in place of the component (B), the flexographic printing plate obtained is inferior in dimensional stability, and in some cases, it may be washed out with an alkaline aqueous solution due to shrinkage of the photosensitive rubber plate. There are things you can't do.

If desired, a polymer other than the thermoplastic elastomer may be used in combination so long as the object of the present invention is not impaired. Examples of such polymers 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 copolymer, acrylonitrile-chloroprene-styrene Copolymers, epichlorohydrin polymers, epichlorohydrin -
Ethylene oxide copolymer, epichlorohydrin-propylene oxide copolymer, epichlorohydrin rubber, chlorinated polyethylene, vinyl chloride copolymer, vinylidene chloride copolymer, chlorinated polypropylene, chlorinated ethylene-
Propylene rubber, ethyl acrylate-acrylonitrile copolymer, butyl acrylate-acrylonitrile copolymer, methyl methacrylate-acrylonitrile copolymer,
Examples thereof include butyl acrylate-styrene-acrylonitrile copolymer. These may be used alone or in combination of two or more.

In the photosensitive composition of the present invention, examples of the photopolymerizable ethylenically unsaturated monomer used as the component (C) include styrene, α-methylstyrene and m-.
Aromatic vinyl monomers such as methylstyrene and p-methoxystyrene; α, β-ethylenically unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile; methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate , Acrylates of alkyl alcohols having 1 to 23 carbon atoms such as t-butyl acrylate and corresponding methacrylates; 2-hydroxyethyl acrylate, 2
Acrylates and corresponding methacrylates of hydroxyalkyl alcohols such as hydroxypropyl acrylate; acrylates and methacrylates of alkoxyalkylene glycols such as methoxyethylene glycol, methoxypropylene glycol; monoethyl maleate, monomethyl fumarate, monoethyl itaconate, etc. Unsaturated polycarboxylic acid monoesters; dimethyl maleate, diethyl maleate, dibutyl maleate, dioctyl maleate, diethyl fumarate, dibutyl fumarate, dioctyl fumarate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate. , Diesters such as dioctyl itaconate; acrylamide, methacrylamide, N, N'-methylenebisacrylamide, N, '- acrylamides and corresponding methacrylamides, such as hexamethylene bisacrylamide, ethylene glycol diacrylate, polyalkylene glycol (alkylene glycol units 2
~ 23) glycol diacrylates and corresponding methacrylates; dihydric trihydric alcohols such as glycerin, pentaerythritol, trimethylolalkane, tetramethylolalkane (alkane is methane, ethane, propane). Acrylates, triacrylates, tetraacrylates, oligoacrylates and corresponding methacrylates; acrylates having acidic functional groups such as 2-acryloyloxyethylsuccinic acid, 2-acryloylethylhexahydrophthalic acid, 2-acryloyloxyethyl acid phosphate And corresponding methacrylates; and the like. These photopolymerizable ethylenically unsaturated monomers may be used alone or in combination of two or more.

In the present invention, the photopolymerizable ethylenically unsaturated monomer is blended in an amount of 5 to 300 parts by weight, preferably 5 to 300 parts by weight, based on 100 parts by weight of the total of the components (A) and (B). It is in the range of 10 to 200 parts by weight. This amount is 5
If the amount is less than 100 parts by weight, the curing of the photosensitive composition due to actinic light will be insufficient, so the resulting flexographic printing plate may have poor mechanical properties, and if it exceeds 300 parts by weight, the rubber of the flexographic printing plate will be poor. Elasticity and solvent resistance tend to decrease, which is not preferable.

The photopolymerization initiator used as the component (D) in the photosensitive composition of the present invention is a compound usually used as a photoreaction initiator, for example, diacetyl,
Α-diketones such as benzyl; acyloins such as benzoin and pivaloin; acyloin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether; anthraquinone,
Polynuclear quinones such as 1,4-naphthoquinone; and the like. These photopolymerization initiators may be used alone or in combination of two or more.

The amount of the photopolymerization initiator (D) compounded is 100 parts by weight in total of the above-mentioned components (A) and (B).
It is in the range of 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight. If this amount is less than 0.1 parts by weight, curing by actinic light during flexographic printing plate preparation will be insufficient, and if it exceeds 10 parts by weight, not all of the added photopolymerization initiator will participate in the reaction. Therefore, it is not preferable because it is uneconomical and the reaction rate to light tends to be slowed due to absorption of irradiated active light.

The photosensitive composition of the present invention may optionally contain
In addition to the components (A) to (D), other commonly used components may be added. Examples of such components include a plasticizer and a storage stabilizer. Examples of the plasticizer include hydrocarbon oils such as naphthene oil and paraffin oil; low molecular weight polystyrene having a molecular weight of 3,000 or less, α-methylstyrene-vinyltoluene copolymer, petroleum resin, polyacrylate, polyester resin, polyterpene. Resins; polyisoprene and hydrogenated products thereof; liquid 1,2- or 1,4-polybutadiene and its terminal modified products; and hydroxides or carboxylates thereof; liquid acrylonitrile-butadiene copolymers and carboxylates thereof; Liquid styrene-butadiene copolymer; and the like. These may be used alone or in combination of two or more.

Since these plasticizers improve the fluidity of the photosensitive composition, they are effective in facilitating the homogenization of each component of the photosensitive composition and facilitating the sheet molding from the photosensitive composition. It also has the effects of promoting the removal of the unexposed areas during the development of the photosensitive rubber plate and adjusting the hardness of the exposed areas. The amount of plasticizer added depends on the desired properties.
Usually, it is selected in the range of 5 to 200 parts by weight, preferably 5 to 100 parts by weight, per 100 parts by weight of the total of the components (A) and (B).

Examples of the storage stabilizer include phenones such as hydroquinone, p-methoxyphenol, pt-butylcatechol, 2,6-di-t-butyl-p-cresol and pyrogallol; benzoquinone and p-toluquinone. , Quinones such as p-xyloquinone; phenyl-α-
Amines such as naphthylamine; and the like. These storage stabilizers may be used alone or in combination of two or more, and the addition amount thereof is usually 10 in total of the component (A) and the component (B).
It is selected in the range of 0.01 to 2 parts by weight per 0 parts by weight.

The photosensitive composition of the present invention has excellent photosensitivity, and therefore, in addition to flexographic printing plates, it is used for photoresists and screens for screen printing, and also for paints, coating agents, adhesives, films and sheets. Objects, impregnated products,
It can be preferably used for other molded articles and the like.

The method for preparing the photosensitive composition of the present invention is not particularly limited and, for example, kneading may be performed using a kneader such as a kneader or a roll mill, and the order of kneading is not particularly limited. The following method can be mentioned as an example of a preferable method. First, the granulated product of the hydrophilic copolymer as the component (A) and the granulated product of the thermoplastic elastomer as the component (B) are mixed. As the mixer at this time, a tumbler mixer, a ribbon blender, or the like is suitable. This mixture is put into a hopper and supplied from the lower part of the hopper to the hopper port of the extruder by a conveyor or the like. The mixture of both copolymers is heated in the barrel of the extruder and kneaded by a screw to uniformly melt and mix.

Next, the photopolymerizable ethylenically unsaturated monomer as the component (C), the photopolymerization initiator as the component (D), and other compounding agents used as necessary are mixed and obtained. The mixture is pressure-fed into the extruder from an intermediate portion of the extruder using a pump or the like, and the homogeneous mixture of both copolymers and the mixture of other compounding agents are uniformly kneaded inside the extruder. Thereby, the photosensitive composition of the present invention can be obtained. The extruder to be used is preferably a twin-screw extruder having two screws having functions of melting, mixing and transferring.

The method for molding the photosensitive composition of the present invention into a sheet is not particularly limited, and for example, a sheet having a desired thickness can be formed using a molding machine such as an extruder, a press or a calender. And it is sufficient. Also, the photosensitive composition is dissolved in a suitable solvent such as chloroform, carbon tetrachloride, trichloroethane, methyl ethyl ketone, diethyl ketone, benzene, toluene, tetrahydrofuran, etc., and this solution is poured into a frame mold, and then the solvent is evaporated. The sheets can also be prepared by:

By heat-pressing, extruding or calendering these sheets, a sheet having a high thickness precision can be obtained, which can be preferably used as a material for a photosensitive rubber plate. In order to suitably produce a sheet-shaped photosensitive composition from the photosensitive composition of the present invention, the uniformly kneaded photosensitive composition is transferred from an extruder to a die.
By passing through a die, the composition is rolled to a predetermined thickness and width and pre-sheeted. The sheet passing through this die is then fed into a calender nip and rolled between two smooth and flat surface calender rolls.

By passing the die before the calender nip, the smoothness and thickness accuracy of the sheet of the photosensitive composition can be greatly improved as compared with the case of adjusting the thickness only by the calender nip. The die temperature when passing the photosensitive composition may be appropriately selected in consideration of the composition of the photosensitive composition, and a suitable die temperature is 150 ° C. or lower,
More preferably, it is 140 ° C. or lower. If the temperature exceeds 150 ° C., there arise problems such that the composition is colored, the washing time with a developing solution becomes long, and the original image reproducibility of the flexographic printing plate obtained is lowered. Since the photosensitive composition of the present invention contains a specific hydrophilic copolymer, the die temperature can be set low.

The photosensitive rubber plate of the present invention comprises a sheet-shaped photosensitive composition laminated on the main surface of a support. The support usually consists of a flexible film or sheet, optionally with a release layer or an adhesive or primer subbing layer. In the present invention, the support may be used without particular limitation, as long as it is one that is commonly used in flexographic printing plates. Examples thereof include flexible films such as polyethylene terephthalate film, polypropylene film and polyimide film; natural rubber, synthetic rubber,
Examples thereof include the above-mentioned sheets backed with an elastic composition such as soft vinyl chloride.

The photosensitive rubber plate of the present invention may be further provided with a cover film. The cover film consists of a flexible cover film and an optional slip film. The flexible cover film constitutes the protector film layer of the photosensitive composition layer, is made of a flexible film, and optionally has a release layer. The flexible cover film can be used without particular limitation as long as it is a commonly used one. Examples thereof include polyethylene terephthalate film, polyethylene film, polypropylene film and polystyrene film. The thickness of the film is usually 75-200μ
m, preferably 100 to 150 μm. If the thickness is less than 75 μm, the protector film has insufficient strength, and the molded photosensitive rubber plate is easily deformed. On the other hand, if it exceeds 200 μm, the film strength becomes too strong, and it becomes difficult to form a sheet from the photosensitive composition.

For laminating a support or a cover film on the surface of the sheet-shaped photosensitive composition, a conventionally known method may be adopted. A support or a cover film may be laminated on both sides of the sheet-shaped photosensitive composition at the same time, and
The support or cover film may be laminated on only one surface and then laminated on the other surface. Lamination is usually performed using a calendar roll. Further, in the photosensitive rubber plate of the present invention, a thin layer of a non-adhesive water-soluble polymer can be provided as a coating layer for the photosensitive composition layer.

The surface of the photosensitive composition generally has strong adhesiveness, and therefore, when the original film is directly attached to the surface,
Air bubbles enter between the photosensitive composition and the film, and active light is diffusely refracted, and the exposure and curing of the photosensitive layer do not proceed, resulting in poor reproducibility of the relief and the surface of the photosensitive composition layer. There is a problem that the original film that adheres to the film cannot be reused.

As a method for solving such a problem, a slip film (hereinafter referred to as "coating material") is formed on the surface of the photosensitive composition.
It is known to coat a thin film referred to as). By providing a layer of such a coating material, the adhesion between the original film and the photosensitive composition is suppressed,
Moreover, the original film can be repeatedly used. As such a coating material, polyamide, cellulose derivative and the like have already been widely used.

On the other hand, the coating material must be dissolved and removed together when the unexposed portion of the photosensitive layer is removed after exposure. However, the above-mentioned known coating material can be suitably used for a photosensitive composition using a conventional halogenated hydrocarbon as a developer, but since it is water-insoluble or poorly water-soluble, it is suitable for a water-developable photosensitive composition. Was difficult to apply. In the present invention, by using a water-soluble polymer as the coating material, it is possible to provide a coating material layer having no problem as described above.

Examples of the water-soluble polymer that can be used in the present invention include polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyethylene oxide, polyethyleneimine and derivatives thereof, but polyvinyl alcohol is preferred. Among them, those having a saponification degree of 60 to 100 mol% are preferable, the saponification degree is 65 to 80 mol%, and the viscosity measured by a Heppler viscometer at a temperature of 20 ° C. is 10%.
Polyvinyl alcohol having a cp or less is particularly suitable.

The method of coating the photosensitive composition with the coating material is not particularly limited, but usually, the coating material solution is previously applied onto the protector film by using a bar coater, an applicator or the like, and then dried. To form a coating material layer, and then the coating material layer is laminated so as to be in close contact with the surface of the photosensitive composition, and pressed with a roller or the like to be in close contact.

The thickness of the coating material is not particularly limited, but is usually adjusted so as to be 10 μm or less after drying. If it exceeds 10 μm, poor adhesion to the original film is likely to occur, and image reproducibility may be impaired. Also,
If it is less than 0.5 μm, the effect of preventing sticking of the original film may not be obtained. A laminate (photosensitive rubber plate) of the photosensitive composition obtained by the above method and a support or a cover film is cut into a desired size.

In order to produce a flexographic printing plate using the photosensitive rubber plate of the present invention, a conventional method can be adopted. That is, the surface laminated with the support of the photosensitive rubber plate is usually exposed with an ultraviolet lamp used for plate making of a flexographic printing plate to form a floor, and then the cover film on the opposite side is exposed. After peeling, the original film is placed on the photosensitive composition layer, and the two are brought into close contact with each other by depressurizing with a vacuum pump, and imagewise exposure is performed.

The unexposed portion of the photosensitive composition of the present invention can be removed in the same manner as conventional development with an aqueous developer. That is, the photosensitive composition which has been imagewise exposed according to a conventional method is brought into contact with the developer filled in the developing machine, and the unexposed portion is scraped off with a brush. The time required for the development depends on the thickness of the photosensitive composition used, the depth of relief (thickness to be eluted), and the accuracy of the printing plate desired for plate making, but it is usually 5 to 20 minutes.

The photosensitive rubber plate of the present invention can be developed not only by a dilute alkaline aqueous solution, but also by a mixed solvent of an alkaline aqueous solution and an alcohol or a ketone, or a mixed solvent of a halogenated organic solvent and an alcohol or a ketone. it can. Examples of the dilute alkaline aqueous solution include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide; ammonia; weak acid alkali metal salts such as lithium carbonate;

The photosensitive rubber plate of the present invention can also be developed with a cationic surfactant such as lauryltrimethylammonium chloride or an amphoteric surfactant such as an alkylaminocarboxylic acid salt. It is preferable to develop with a developing agent or a nonionic surfactant. As the anionic surfactant, known ones can be used without particular limitation. For example,
Examples thereof include alkyl benzene sulfonate, alkyl sulfate ester salt, and succinic acid dialkyl ester sulfonate.

As the nonionic surfactant, known ones can be used without particular limitation. Examples thereof include polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene alkyl ether phosphates and the like, compounds having a polyoxyethylene chain in the molecule and having surface activity, Further, sorbitan fatty acid ester, glycerin fatty acid ester, pentaerythritol fatty acid ester, and fatty acid alkanolamide can be mentioned.

Among these, from the viewpoints of developing property, reproducibility of the original image of the flexographic printing plate, not contaminating the developing device, and having no adverse effect on human body and working environment, etc.
A fatty acid alkanolamide is preferable, and a fatty acid alkanolamide of 1: 2 mol type is most preferable in terms of developability and water solubility of the surfactant itself. Examples of 1: 2 molar fatty acid alkanolamides include coconut oil fatty acid diethanolamide, lauric acid diethanolamide, stearin 3 diethanolamide, and the like. In addition,
Examples of 1: 1 molar fatty acid alkanolamides include fatty acid monoethanolamides corresponding to the above fatty acid diethanolamides.

The concentration of the developing solution is not particularly limited as long as it can be developed, but it is usually 0.1 to 4% by weight when an alkaline aqueous solution is used, and is effective when an aqueous surfactant solution is used. The concentration of the component is usually 0.5 to 20% by weight. If the density is too low, the developability will decrease, making it difficult to remove the unexposed areas, and the resulting printing plate will have poor reproducibility of the original image. On the other hand, if the concentration is too high,
Although the developability does not change, a great deal of labor is required for rinsing with water and treating the waste liquid after development.

The development temperature may be room temperature, but the time required for development can be shortened by raising the temperature. However, if the temperature exceeds 90 ° C., depending on the developing device used, water easily evaporates, the concentration of the developer changes, and there is a risk of burns. The preferred temperature is 40 to 70 ° C.
In the present invention, the printing plate after development is immediately treated with, for example, 7
It can be used by drying with warm air at 0 ° C for 10 to 20 minutes, but by rinsing the surface from which the unexposed area has been removed with water to remove the developer, printing plates with better reproducibility of the original image can be obtained. Can be If necessary, the surface from which the unexposed portion is removed may be post-exposed using the same light source as imagewise exposure or treated with halogen for the purpose of reducing the tackiness of the printed surface. Good.

The preferred embodiments of the present invention are listed below. 1. (A) (a) Phosphate ester group-containing unsaturated monomer 5
Copolymerization of a monomer mixture comprising 30% by weight, (b) 40 to 90% by weight of a conjugated diene monomer, and (c) 0 to 50% by weight of a monoolefinic unsaturated monomer other than (a). 35-80 parts by weight of the phosphorus-containing hydrophilic copolymer thus obtained,
(B) 65 to 20 parts by weight of the thermoplastic elastomer (however,
The total of (A) and (B) is 100 parts by weight. ),
(C) 5 to 300 parts by weight of a photopolymerizable ethylenically unsaturated monomer based on 100 parts by weight of (A) and (B) in total,
And (D) a photosensitive composition containing 0.1 to 10 parts by weight of a photopolymerization initiator based on 100 parts by weight of (A) and (B) in total.

2. The component (A) is composed of (a) 5 to 20% by weight of a phosphoric acid ester group-containing unsaturated monomer, (b) 50 to 80% by weight of a conjugated diene monomer, and (c) a monoolefin system other than (a). Embodiment 1 of the above which is a phosphorus-containing hydrophilic copolymer obtained by copolymerizing a monomer mixture consisting of 10 to 40% by weight of an unsaturated monomer.

3. The component (A) is composed of (a) 5 to 30% by weight of a phosphoric acid ester group-containing unsaturated monomer, (b) 40 to 90% by weight of a conjugated diene monomer, and (c) a monoolefin system other than (a). 1. A phosphorus-containing hydrophilic copolymer obtained by copolymerizing a monomer mixture comprising 0 to 50% by weight of an unsaturated monomer and (d) 10 parts by weight or less of a polyfunctional vinyl monomer. Embodiment.

4. The embodiment according to any one of 1 to 3 above, wherein the thermoplastic elastomer as the component (B) is a thermoplastic elastomer block copolymer. 5. 5. The embodiment of the above 4, wherein the thermoplastic elastomeric block copolymer comprises a thermoplastic non-elastomeric block copolymer and an elastomeric block.

6. The thermoplastic elastomeric block copolymer is polystyrene-polybutadiene-polystyrene block copolymer or polystyrene-polyisoprene-
6. The embodiment according to 5 above, which is a polystyrene block copolymer. 7. (A) component, (B) component, (C) component and (D)
The amounts of the components are 40 to 70 parts by weight and 60 to 30 parts, respectively.
The embodiment according to any one of 1 to 6 above, which is parts by weight, 10 to 200 parts by weight, and 1 to 5 parts by weight.

8. A photosensitive rubber plate which is a laminate comprising a support and a layer of the photosensitive composition according to any one of Embodiments 1 to 7 formed on the main surface thereof. 9. 9. The embodiment of the above 8, wherein a coating layer made of a water-soluble polymer is provided on the photosensitive composition layer.

10. 9. The embodiment of 9 above, wherein the water-soluble polymer is selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyethylene oxide, polyethyleneimine and derivatives thereof. 11. The embodiment of claim 9 wherein the water soluble polymer is polyvinyl alcohol. 12. The eleventh embodiment above, wherein the polyvinyl alcohol has a saponification degree of 60 to 100 mol%.

13. Polyvinyl alcohol has a saponification degree of 6
The embodiment according to the above 11, wherein the viscosity by a Heppler viscometer at a temperature of 20 ° C. of 5 to 80 mol% is 10 cp or less. 14. A method for producing a photosensitive rubber plate, which comprises kneading the photosensitive composition according to any one of Embodiments 1 to 7, extruding the composition through a die, calendering it, and laminating it on a support.

15. The fourteenth embodiment, wherein the die temperature is 150 ° C or lower. 16. A method for producing a flexographic printing plate, which comprises exposing the photosensitive rubber plates of the above-mentioned Embodiments 8 to 13 imagewise and then removing the unexposed portions with an aqueous developer.

17. The 16th embodiment as described above, wherein the aqueous developer is selected from an anionic surfactant and a nonionic surfactant. 18. The embodiment of claim 17 wherein the nonionic surfactant is an aliphatic alkanolamide. 19. A flexographic printing plate obtained by the method according to Embodiments 16 to 18 above.

[0079]

INDUSTRIAL APPLICABILITY The photosensitive composition of the present invention is excellent in photosensitivity, processability and alkali solubility, and the exposed / cured product obtained therefrom is excellent in water-resistant ink resistance, transparency, strength and rubber elasticity at low temperature. It is suitable for use as a water-developable photosensitive rubber plate material.

Further, the photosensitive composition obtained by the present invention has high sensitivity so that the exposure time can be shortened and the solubility in a developing solution is extremely high, so that development processing can be carried out in about 5 to 10 minutes. In addition, since it has a feature that it can be printed immediately after drying, it is suitably used as a flexographic printing plate. The flexographic printing plate has a simple plate-making process and can significantly reduce the working time as compared with the conventional flexographic printing plate.

Further, when the coating material layer is formed on the surface of the photosensitive composition layer, the adhesion between the photosensitive composition layer and the original image film is suppressed, and the original image film can be easily detached and reused. to enable. Further, the flexographic printing plate of the present invention is not only printable with conventional solvent-type flexographic inks, but also has good water-resistant ink resistance, so it is used in place of solvent-type flexographic inks from the viewpoint of air pollution. It is possible to print with a certain aqueous flexo ink.

[0082]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In this example, parts and% are by weight unless otherwise specified. In the present invention, the photosensitive rubber plate was produced by the following method unless otherwise specified.

(Production Method of Photosensitive Rubber Plate) The uniformly mixed photosensitive composition was fed into two calender rolls so that the thickness of the two sheets was 0.
Calendar between 1 mm polyethylene terephthalate film. Then, air is blown to cool the sheet to obtain a photosensitive rubber plate.

The photosensitive rubber plate may be laminated with a polyethylene terephthalate film to which a coating material is applied in advance (cover sheet), if necessary. Further, each characteristic of the photosensitive composition, the photosensitive rubber plate and the flexographic printing plate is obtained as follows.

(1) Workability The photosensitive composition is judged according to the following criteria from the situation when it is wound around a 6-inch roll at 80 to 120 ° C. A: Good roll wrapping with no shrinkage problems C: Poor wrapping, high tackiness and difficult to process

(2) Alkali-soluble When the sheet of the photosensitive composition or the unexposed photosensitive layer of the photosensitive rubber plate is dissolved and removed in a 1% aqueous sodium hydroxide solution at 40 ° C. with a nylon brush, The time required to dissolve 1/3 (1 mm) of the sheet thickness is shown.
The lower this value, the higher the alkali solubility.

(3) Hardness A sheet of the photosensitive composition or both sides of the photosensitive rubber plate are exposed for 10 minutes using an ultraviolet lamp having an illuminance of 5 mW / cm ² to obtain a cured product. The hardness of this cured product is JI
Measure according to SK6301.

(4) Water-resistant ink resistance (swelling degree) Both sides of the sheet of the photosensitive composition or the photosensitive rubber plate were subjected to 10 minutes each without a negative film, and the illuminance was 5 mW.
/ Cm ² of the cured sheet obtained by exposure with an ultraviolet lamp, punched into a disk shape having a diameter of 3 cm, and the degree of swelling when immersed in a commercially available flexo aqueous ink solution for 24 hours ( The weight increase rate is expressed as a percentage). The lower this value, the better the water resistant ink resistance.

(5) Development Speed Six pieces of 3 cm square are cut out from a sheet of the photosensitive composition or a photosensitive rubber plate to obtain a sample. From this sample,
Peel off the polyethylene terephthalate film on the developing side, and use a developing machine for photosensitive flexo plates (JOW manufactured by JEOL Seiki)
-A2-SS type), using a developing solution (2.0
% Aqueous solution) for 3, 6, 9, 12, 15, 18 minutes. Each sample after development is rinsed with water and dried at 70 ° C. for 20 minutes. From the thickness of the sheet before development and the thickness of each sample after drying, the development rate (the amount of change in the thickness when the sheet was developed for 1 minute) was obtained and used as a measure of developability.

(6) Resolution The entire surface of one side of the sheet of the photosensitive composition is 5 mW / c.
exposure using m ² ultraviolet lamp comprises an ultraviolet exposure machine (JEOL Seiki JE-A2-SS type). Then
The polyethylene terephthalate film on the surface opposite to the exposed surface (non-exposed surface) was peeled off to give an optical density of 3.
A negative film for reproducibility evaluation containing various test patterns of No. 8 is brought into close contact with this surface, and image-forming exposure is performed for a predetermined time by the above-mentioned exposure machine (exposure wavelength is 320 to 400 nm). The negative film is peeled off, and the unexposed portion is dissolved and removed by a developing machine for the above-mentioned photosensitive flexographic plate in a 1% aqueous sodium hydroxide solution at 40 ° C. (in some cases 50 ° C.) using a nylon brush. The dissolution time is the time required to remove the sheet of the photosensitive composition by 1.5 mm (determined from the development rate determined above). Then, it is rinsed with water, dried at 70 ° C. for 20 minutes, and the surface from which the unexposed portion has been removed is re-exposed with the above light source for 10 minutes to create a relief image for resolution evaluation.

With respect to this relief image, the reproduction state of the fine line of the convex image portion and the engraved state of the fine line of the concave image portion are observed with a stereoscopic microscope of 50 times, and evaluated according to the following criteria.

Reproducibility of 0.2 mm wide convex fine line A case where the shape of the convex fine line is not distorted or thickened and is reproduced with the same width as the negative is regarded as “completely reproduced state”, and according to the following criteria. evaluate. A: The shape of the convex fine line is not distorted or thickened (a negative is completely reproduced). B: The convex fine line is slightly distorted, and a part of it is thickened (a negative is almost reproduced). C: The convex fine lines are severely distorted and the thickness is also nonuniform (a state where reproduction of the negative is incomplete).

Reproducibility of 0.7 mm wide concave fine line When the concave fine line having a width of 0.7 mm and a depth of about 150 μm does not have wavy knurls, the edges are sharp, and the groove of the concave fine line is deeply carved. Is regarded as "a state where the negative is completely reproduced", and evaluated according to the following criteria. A: The groove of the concave fine line is deep and the edge is also carved sharply (a negative is completely reproduced). B: The groove of the concave fine line is slightly shallow, but there is no problem in practical use (a negative is reproduced almost). C: The groove of the concave fine line is shallowly carved (the reproduction of the negative is incomplete).

Halftone dot reproducibility The case where 65 lines and 5% halftone dots are reproduced in the same state as the negative is regarded as "completely reproduced state" and evaluated according to the following criteria. A: 65 lines, 5% halftone dots are completely reproduced (negative is completely reproduced). B: Some halftone dots are missing (a negative is almost reproduced). C: The lack of halftone dots is severe (the reproduction of the negative is incomplete). In all the tests, the score A indicates that the printing plate has excellent reproducibility of the original image.

(7) Rubber elasticity BS-903, Pt. A. 8 In accordance with the trypso test method, measurement is performed using the flat portion of the relief image evaluation sample. The return angle θ _d after the pendulum hits the sample is calculated, and the impact resilience value R is calculated by the following formula R = [(1-COS θ _d ) / (1-COS θ _o )] x1
00 and evaluate based on this value according to the following criteria. It should be noted that θ _o is the angle of the pendulum before the test, which is 45 ° in this embodiment.

A: The impact resilience value is 60% or more. B: The impact resilience value is 50% or more and less than 60%. C: The impact resilience value is less than 50%. The higher the impact resilience value, the better the rubber elasticity. (8) Surface tackiness The presence or absence of tackiness between the photosensitive composition layer and the negative film is observed.

(9) Measurement of Thickness and Thickness Accuracy of Photosensitive Composition Layer A sheet of the photosensitive composition or a photosensitive rubber plate was set at 10 × 10.
Cut into cm pieces, (from the outside of the support and cover film) thickness gauge (linear dial gauge, Ozaki Seisakusho)
Is used to measure the thickness t of the sheet, and the thickness accuracy is obtained from the following equation. Plate thickness (mm): x = Σt / n Range (mm): R = t _max −t _{min The} smaller the range (R) obtained by the above equation, the better the thickness accuracy of the composition sheet. However, n indicates the number of measurement points, and t _max and t _min indicate the maximum and minimum values of the measured thickness, respectively.

(10) Warp Deformation of Photosensitive Composition Sheet Surface of end face of photosensitive composition sheet obtained by peeling cover film from photosensitive composition sheet or photosensitive rubber plate cut into 30 cm × 10 cm Measure the lifting height from the flat desk surface of. The lower the lifting height from the desk, the better the shrinkability of the sheet.
Evaluation is based on the following criteria. A: The edge surface of the composition sheet was hardly lifted from the desk. B: The end surface of the composition sheet is lifted by 3 to 10 mm above the desk. C: The end surface of the composition sheet is lifted by 11 mm or more from the desk.

(11) Measurement of Surface Roughness (Ra) of Composition Layer After peeling the cover film from the photosensitive rubber plate cut into 1 cm × 1 cm, the surface roughness was measured with a laser microscope (color scanning laser microscope). 1LM211, manufactured by Lasertec). The measuring range is 200
It is set to μm × 200 μm.

The smaller the surface roughness Ra, the better the smoothness of the composition sheet. Evaluation is based on the following criteria. A: The average surface roughness is in the range of 0.3 μm or less. B: The average surface roughness is in the range of 0.4 to 1.0 μm. C: The average surface roughness is in the range of 1.1 μm or more.

(12) Molded State (Foamed State) of Sheet of Photosensitive Composition The number of bubbles existing in the sheet of the photosensitive composition having a thickness of 3 mm cut into a size of 30 cm × 10 cm is visually observed. . It is better that there are no bubbles. Evaluation is based on the following criteria. A: No bubbles are seen in the composition sheet. B: 1-2 small bubbles are seen in the composition sheet. C: Large bubbles are present or a large number of small bubbles are present in the composition sheet.

(13) Molded state of the sheet of the photosensitive composition (transparency) The transparency of the sheet of the photosensitive composition having a thickness of 3 mm cut into a size of 30 cm x 10 cm is visually observed. It is better that there is no turbidity. Evaluation is based on the following criteria. A: The transparency of the composition sheet is at a level that does not hinder practical use. B: Some turbidity is observed on the composition sheet. C: The composition sheet is extremely turbid, which hinders the pattern reproduction state.

Reference Example 1 Polymerization was carried out at 50 ° C. in an autoclave with an internal volume of 10 liters using the monomers and polymerization agents shown in Table 1, and a terminating agent was added when the conversion of polymerization reached 95%. The reaction was stopped and cooled with water to obtain an emulsion. After freeze-coagulating this emulsion, separating the crumbs and washing with water,
It was vacuum dried at 60 ° C. to obtain a copolymer.

[0104]

[Table 1] Amount of monomers and polymerization agents (parts) Butadiene 60 Methyl acrylate 9 Phosphoric acid ethylene methacrylate 20 Styrene 10 Divinylbenzene 1 Sodium dodecylbenzenesulfonate 4 Potassium persulfate 0.3 t-Dodecyl mercaptan 0.4 Water 200

Reference Example 2 A copolymer was obtained in the same manner as in Reference Example 1 except that neither divinylbenzene, styrene nor methyl acrylate was used, and instead of these, 20 parts of methyl methacrylate was used.

Comparative Reference Example 1 A copolymer was obtained in the same manner as in Reference Example 1 except that divinylbenzene and styrene were not used, and the amount of phosphoric acid ethylene methacrylate was 3 parts and the amount of methyl methacrylate was 20 parts.

Example 1a The copolymer obtained in Reference Example 1 and the compounding agents shown in Table 2 were kneaded by a kneader at 150 ° C., and the temperature was lowered to 120 ° C. when uniformly kneaded. Add the compounding agent of
Further kneading was continued to prepare a photosensitive composition.

[0108]

[Table 2] Amount of compounding agent (parts) Copolymer 65 Styrene-butadiene-styrene block copolymer (SBS) ¹⁾ 35 Liquid polybutadiene ²⁾ 50 2,6-Di-t-butyl-p-cresol 0.2 Note 1) Shell Chemical Co., Califlex TR, KX-65 2) Nippon Soda Co., Ltd., Nisso PB, B-1000

[0109]

[Table 3] Amount of compounding agent (parts) 1,6-hexanediol diacrylate 10 1,6-hexanediol dimethacrylate 5 benzoin methyl ether 1 methylhydroquinone 0.02

Table 4 shows the physical properties of the photosensitive composition thus obtained. Next, these photosensitive compositions were sandwiched between two sheets of polyethylene terephthalate film having a thickness of 0.1 mm, and molded using a vacuum press at 90 to 130 ° C. to have a thickness of 3.0 mm. The solid composition retained solidity and had no problem in handleability.

Next, one of the polyethylene terephthalate films was peeled off, and the surface of the photosensitive layer had an optical density of 3.
The negative film of No. 8 was adhered, and a commercially available ultraviolet exposure machine for photosensitive resin (illuminance: 5 mW / cm ² , wavelength: 320 to 400)
nm) and then developed with a 1% aqueous sodium hydroxide solution, the unexposed area was completely dissolved and removed, and a flexographic printing plate faithful to the original image was obtained. This printing plate has rubber elasticity and has hardness (Shore A,
(Measured at 20 ° C.) was 52. Also, when this printing plate was subjected to flexographic printing using a water-based ink, a printed matter faithful to the original image was obtained.

Examples 1b and 1c, Comparative Examples 1a to 1c In the same manner as in Example 1a, the same copolymers as in Example 1a were used to prepare the photosensitive compositions shown in Table 4, and flexographic printing plates were further prepared. Created. The physical properties are shown in Table 4.

[0113]

[Table 4] Note 1) Styrene-isoprene-styrene block copolymer [Shell Chemical Co., Ltd., Kraton TR1107] 2) Styrene-butadiene copolymer [Nippon Zeon, NS-310]

As is clear from Table 4, the copolymer obtained from the monomer mixture containing the phosphoric acid ester group-containing unsaturated monomer and the like in the specific ratio and the thermoplastic elastomer are contained in the specific ratio. The photosensitive composition of the present invention is excellent in processability, developability with an aqueous alkaline solution, and water resistance and hardness of a cured product, and is suitable as a water-soluble photosensitive rubber plate material.

On the other hand, in Comparative Example 1a in which the thermoplastic elastomer was used in excess, it took a long time to dissolve and remove the unexposed portion, and the printing plate obtained had poor reproducibility of the original image. . Further, in Comparative Example 1b in which the thermoplastic elastomer was not used, only the printing plate having poor water-resistant ink resistance and poor reproducibility of the original image could be obtained. Further, in Comparative Example 1c using a non-thermoplastic elastomer instead of the thermoplastic elastomer, the unexposed portion could not be dissolved and removed due to shrinkage of the plate, and a printing plate could not be obtained.
The evaluation of resolution and rubber elasticity was stopped.

Examples 2a to 2c, Comparative Examples 2a to 2c Photosensitive compositions were obtained in the same manner as in Example 1a except that the monomer mixture shown in Table 5 was used. The physical properties are shown in Table 5.

[0117]

[Table 5]

As is clear from Table 5, by using the copolymer specified in the present invention, a photosensitive composition excellent in processability, developability in an alkaline aqueous solution, and water resistance and hardness of a cured product is obtained. Which is suitable as a water-soluble photosensitive rubber plate material.

On the other hand, in Comparative Example 2a in which the amount of butadiene units was reduced, it took time to dissolve the unexposed area, the reproducibility of the original image was poor, and only a printing plate having low strength was obtained. Further, Comparative Example 2b in which the amount of the unsaturated monomer containing a phosphoric acid ester group is reduced, and Comparative Example 2c in which a copolymer obtained by using methacrylic acid in place of the monomer is used.
Then, the unexposed portion could not be dissolved and removed, and the printing plate could not be obtained. Therefore, the evaluation of the resolution and the rubber elasticity was stopped.

Examples 3a to 3f and Comparative Example 3a Using the copolymer obtained in Reference Example 1, a photosensitive composition was prepared in the same manner as in Example 1a, and a flexographic printing plate was prepared. . However, the exposure time is 4 minutes. Using the developers shown in Table 6, the same evaluations as in Example 1a were performed. The results are shown in Table 6.

[0121]

[Table 6]

Example 3g A printing plate excellent in reproducibility of an original image was obtained in the same manner as in Example 3a except that the copolymer obtained in Reference Example 2 was used. I was able to. Furthermore, when it was subjected to flexographic printing using a water-wash ink, a printed matter faithful to the original image was obtained. The results are shown in Table 7.

Comparative Example 3b Evaluations were made in the same manner as in Example 3a except that the copolymer obtained in Comparative Reference Example 1 was used, but the friction between the photosensitive composition and the brush was too large, and the composition was evaluated. Development was stopped because the product had detached from the developing machine. Therefore, a printing plate could not be obtained. The results are shown in Table 7.

[0124]

[Table 7]

As shown in the results of Tables 6 and 7,
A flexographic printing plate excellent in reproducibility of the original image was obtained in a short time, and when the obtained flexographic printing plate was subjected to flexographic printing using an aqueous ink, a printed product faithful to the original image was obtained. In particular, when an anionic surfactant or a nonionic surfactant is used as the developer, it can be seen that the development time is short and the resolution and the water resistance of the ink are excellent. This feature is remarkable when coconut oil fatty acid diethanolamide is used.

Reference Example 3 A coating material solution consisting of 10 parts of polyvinyl alcohol having a saponification degree of 70 mol% and 90 parts of water was prepared, and a coating solution having a thickness of 1 was prepared.
1/100 on the surface of 25μm polyester film
It was applied using a 0-inch coater and dried in a drier at 110 ° C. for 1 minute to prepare a polyester film (cover film) P having a coating layer on the surface. Subsequently, a coating solution composed of 10 parts of ethyl cellulose and 90 parts of chloroform was prepared, and a cover film C was prepared by the same method.

Example 4a Reference Example 1 except that the monomers and polymerizing agents shown in Table 8 were used.
A copolymer was obtained in the same manner as in.

[0128]

[Table 8] Amount of monomers and polymerization agents (parts) Butadiene 50 Butyl acrylate 35 Ethylene methacrylate phosphate 15 Sodium dodecylbenzenesulfonate 2 Potassium persulfate 0.3 t-Dodecyl mercaptan 0.4 Water 200

Next, with respect to 100 parts of this copolymer, 20 parts of nonaethylene glycol dimethacrylate as a photopolymerizable ethylenically unsaturated monomer, 20 parts of nonaethylene glycol acrylate, and 1 part of benzoin methyl ether as a photopolymerization initiator. 0.5 parts and 0.2 parts of hydroquinone as a storage stabilizer were added, and the mixture was placed in a plabender for 10 minutes at 80 ° C.
Was kneaded to prepare a photosensitive composition.

Next, this composition was applied to two sheets having a thickness of 125 μm.
It was sandwiched between the polyethylene terephthalate films of Example 1 and was vacuum molded to have a thickness of 3.0 mm. Then, the polyethylene terephthalate film on one surface was peeled off, the coating material surface of the polyethylene terephthalate film having the coating material layer obtained in Reference Example 3 was placed on the surface of the photosensitive layer, and pressure-bonded with a roller. The entire surface of the polyethylene terephthalate film on the other surface (the surface not having the coating material layer) of the obtained photosensitive rubber plate was exposed to ultraviolet rays to perform back exposure, and then polyethylene on the surface on which the coating material was laminated. Except for the terephthalate film, a negative film having an optical density of 3.8 was brought into close contact with the photosensitive layer, and a commercially available ultraviolet exposure machine for photosensitive resin (illuminance: 5 mW / cm ² , exposure wavelength: 320 to 4) was used.
After exposure at 00 nm) for 5 minutes, development was carried out using a 1% aqueous sodium hydroxide solution. As a result, the unexposed area was completely dissolved and removed, and a flexographic printing plate faithful to the original image was obtained. This printing plate had rubber elasticity and had a hardness (Shore A, measured at 20 ° C.) of 59. Also, when this printing plate was subjected to flexographic printing using a water-based ink, a printed matter faithful to the original image was obtained. The results are shown in Table 10.

Examples 4b to 4d and Comparative Examples 4a to 4c Copolymers were prepared in the same manner as in Example 4a except that the monomers shown in Table 10 were used. The operation was also performed in the same manner as in Example 4a. The results are shown in Table 10.

Example 4e The compounding ingredients shown in Table 9 were kneaded together with the copolymer obtained in the same manner as in Example 4d in a kneader at a kneading temperature of 150 ° C., and the temperature was 110 at the time of uniform kneading. Lowered to ℃,
The compounding ingredients shown in Table 3 were added, and the mixture was kneaded for 10 minutes to prepare a photosensitive composition.

[0133]

[Table 9] Amount of compounding agent (parts) Copolymer 65 Styrene-butadiene-styrene block copolymer (SBS) ¹⁾ 35 Liquid polybutadiene ²⁾ 40 2,6-Di-t-butyl-p-cresol 2 Note 1 ) Shell Chemical Co., Califlex TR, KX-65 2) Nippon Soda Co., Nisso PB, B-1000 Using this composition, a flexographic printing plate was obtained in the same manner as in Example 4a and evaluated. I did. The results are shown in Table 10.

Comparative Example 4d A flexographic printing plate was obtained in the same manner as in Example 4a except that the cover film C was used instead of the cover film P. The evaluation results are shown in Table 10.

[0135]

[Table 10]

As is clear from Table 10, by coating the photosensitive composition layer with a coating material, adhesion with the negative film is prevented, the negative film can be easily desorbed, and it does not swell in the aqueous ink. Moreover, a photosensitive rubber plate capable of easily forming a relief having excellent reproducibility can be obtained. By using the flexographic printing plate on which this relief is formed, it is possible to obtain a printed matter that is faithful to the original image up to a fine pattern.

On the other hand, in Comparative Example 4a in which the amount of butadiene units was small, the water resistance of the ink was poor, the reproducibility of the original image was poor, and only a printing plate with low strength was obtained. Further, in Comparative Example 4b in which the amount of the phosphoric acid ester group-containing unsaturated monomer was reduced, and in Comparative Example 4c in which the copolymer obtained by using the acidic monomer in place of the monomer was used, the unexposed portion was Since it could not be dissolved and removed, and a printing plate could not be obtained,
The evaluation of resolution and rubber elasticity was stopped. Further, in Comparative Example 4d using ethyl cellulose as a coating material, although it did not have surface tackiness, it was insoluble in a 1% sodium hydroxide aqueous solution, so that it was not developed and a pattern was not formed, so the evaluation was stopped.

Example 5a 65 parts of the copolymer obtained in Reference Example 1, 35 parts of styrene-butadiene-styrene block copolymer (SBS) [Califlex TR1116 (manufactured by Shell Chemical Co.)] and 2,
0.2 parts of 6-di-t-butyl-p-cresol were automatically metered into the twin-screw extruder after premixing with a ribbon blender. In the extruder, after melt-mixing the pre-mixture, a solution of the composition shown in Table 11 which has been heated and stirred and dissolved in advance is pumped and injected from the middle part of the extruder to obtain the melt mixture and the solution. After kneading, degassing and filtering on the way, 120 ° C as a photosensitive composition
Extruded through the die.

Using this photosensitive composition, a photosensitive rubber plate was prepared by the above method. The characteristics of this photosensitive rubber plate were evaluated. The results are shown in Table 13.

[0140]

[Table 11] Component amount (parts) Liquid polybutadiene rubber ^{* 1)} 50 1,6 Hexanediol diacrylate 15 Benzoin dimethyl ether 1 Methylhydroquinone 0.02 Note) * 1) Nisso PB, B-1000 (Nippon Soda Co., Ltd.)

Example 5b A photosensitive composition was obtained in the same manner as in Example 5a except that the composition of the copolymer and the like was changed as shown in Table 12, and a photosensitive rubber plate was prepared therefrom. The characteristics of this photosensitive rubber plate were evaluated. The results are shown in Table 13.

[0142]

[Table 12] Component Amount (parts) Copolymer 65 Styrene-butadiene-styrene block copolymer (SBS) ^{* 1)} 25 Styrene-isoprene-styrene block copolymer (SIS) ^{* 2)} 10 2,6-di -T-butyl-p-cresol 0.2 Note) * 1) Califlex TR1116 (manufactured by Shell Chemical Co., Ltd.) * 2) Kraton TR1107

Examples 5c to 5e, Comparative Examples 5a to 5b Photosensitive compositions were prepared in the same manner as in Example 5a except that the composition of the photosensitive composition and the die temperature were changed as shown in Table 13. A photosensitive rubber plate was prepared. The characteristics of each of these photosensitive rubber plates were evaluated. The results are shown in Table 13.
Shown in.

Example 5f The components shown in Table 2 were kneaded using a kneader at 150 ° C. When a uniform kneaded product is obtained, the kneading temperature is 120 ° C.
And the components shown in Table 3 (however, 1,6-hexanediol dimethacrylate was used in place of 1,6-hexanediol dimethacrylate) were added and kneading was continued to obtain a photosensitive composition. I got a thing. This composition was sandwiched between polyethylene terephthalate supports having a thickness of 0.1 mm, and a sheet was molded using a vacuum press to a thickness of 3 mm to prepare a photosensitive rubber plate. The characteristics of this photosensitive rubber plate were evaluated. The results are shown in Table 13.

Example 5g Each of the components shown in Table 2 was dissolved in a mixed solvent of trichloroethane and toluene in a weight mixing ratio of 40/60 to a concentration of 30%. Each component shown in Table 3 (however,
1,6-hexanediol diacrylate was used instead of 1,6-hexanediol dimethacrylate. ) Was added and mixed by stirring to obtain a uniform mixed solution.

Next, this uniform mixed solution was provided on a polyethylene terephthalate support having a thickness of 0.1 mm and a thickness of 3.
It was cast in a 0 mm frame and dried. Further, casting and drying were repeated to obtain a photosensitive rubber plate as a sheet having a predetermined thickness. The characteristics of this photosensitive rubber plate were evaluated. The results are shown in Table 13.

[0147]

[Table 13]

From the results shown in Table 13, when the photosensitive composition of the present invention is used, a flexographic printing plate excellent in developability and resolution is obtained, whereas the composition is out of the range of the present invention. It can be seen that when the composition is used, it cannot be developed with an alkaline developer, or only a flexographic printing plate having a remarkably inferior resolution can be obtained even if development is possible. Further, when the sheet of the photosensitive composition of the present invention is molded using a die, a sheet having excellent thickness accuracy and smoothness is obtained, and the reproducibility of the original image is also excellent, especially the temperature of the die. It can be seen that a flexographic printing plate excellent in these properties can be obtained when the temperature is 140 ° C. or lower.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location G03F 7/038 (72) Inventor Ichiro Konishi 1-2-1 Yokou, Kawasaki-ku, Kanagawa Prefecture Japan ZEON Corporation Research and Development Center (72) Inventor Tatsuo Usui 1-2-1 Yokou, Kawasaki-ku, Kawasaki-shi, Kanagawa ZEON Corporation Research and Development Center

Claims (5)

[Claims] 1. (A) 5 to 30% by weight of a phosphoric acid ester group-containing unsaturated monomer (A), and (b) a conjugated diene monomer 40.
To 90% by weight and (c) a monomer mixture of 0 to 50% by weight of a monoolefinic unsaturated monomer other than (a) are copolymerized, and a phosphorus-containing hydrophilic copolymer 35 to 80 is obtained.
Parts by weight, (B) 65 to 20 parts by weight of the thermoplastic elastomer (however,
The total of (A) and (B) is 100 parts by weight. ), (C) 5 to 300 parts by weight of a photopolymerizable ethylenically unsaturated monomer based on 100 parts by weight of (A) and (B) in total,
And (D) a photosensitive composition containing 0.1 to 10 parts by weight of a photopolymerization initiator based on 100 parts by weight of (A) and (B) in total. 2. A photosensitive rubber plate which is a laminate comprising a support and a layer of the photosensitive composition of claim 1 formed on the main surface thereof. 3. A process for producing a photosensitive rubber plate, which comprises kneading the photosensitive composition of claim 1, extruding it through a die, and then laminating it on a support by calendering. 4. After exposing the photosensitive rubber plate of claim 2,
A method for producing a flexographic printing plate, which comprises removing an unexposed portion with an aqueous developer. 5. A flexographic printing plate obtained by the method of claim 4.