JPH0258059A - Photosensitive resin composition - Google Patents

Abstract

PURPOSE:To make it possible to develop the subject composition with a water- based developer, and to improve the durability of the composition against a water base ink after photocuring the composition by incorporating two kinds of specified conjugated diene copolymers in the composition. CONSTITUTION:The composition for a flexoprinting plate is composed of 50-90 pts.wt. of the conjugated diene copolymer (A), 10-50pts.wt. of the conjugated diene copolymer (B), 10-200pts.wt. of a photopolymerizable unsatd. monomer per 100pts.wt. of the total of the components A and B, and 0.1-10pts.wt. of a photopolymerization initiator per 100pts.wt. of the total of the components A and B. The component (A) is composed of 40-90mol.% of a conjugated diene unit (a), 0.5-10mol.% of an alpha,beta-ethylenically unsatd. carboxylic acid unit (b), 0.1-5mol.% of a polyfunctional vinyl compd. unit and 0-59.4mol.% of a monoolefinic unsatd. compd. unit (c). The component (b) is composed of 30-90mol.% of the component (a), 0-30mol.% of the component (b) and 5-70mol.% of the component (c), and is composed of the copolymer having a number- average mol.wt. of 5,000-100,000.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photosensitive resin composition, and more particularly, it is capable of using water or an aqueous developer, and has sufficient properties against aqueous inks. The present invention relates to a photosensitive resin composition capable of providing a durable solid type flexographic printing plate.

[Conventional technology]

Conventionally, photosensitive resin compositions for flexographic printing include: 1.
Those based on 2-polybutadiene, those based on styrene-isoprene-styrene block copolymer,
Known materials include those based on liquid unsaturated polyester and those based on carboxyl group-containing polymer.

However, for those based on 1,2-polybutadiene or styrene isoprene-styrene block copolymer, a halogenated organic solvent must be used as a developer.
Unfavorable for safety and hygiene. Moreover, since a material based on liquid unsaturated polyester is in a liquid state, it is more inconvenient to use than a solid material.

Furthermore, a conjugated diene copolymer soluble in an alkaline aqueous solution has been proposed as a component of a photosensitive resin composition for photoresists (Japanese Patent Publication No. 58-1140), but its transparency is insufficient. There was also room for improvement in rubber elasticity.

Further, the photocurability of the copolymer itself was insufficient.

Furthermore, recently, a conjugated diolefin (diene) hydrocarbon (A) and an α,β-ethylenically unsaturated carboxylic acid (B) are used as essential components, and a monoolefin-based unsaturated compound (D) is added to the essential components. A photosensitive resin composition containing a copolymer (1) containing a photopolymerizable unsaturated monomer (II) and a photopolymerization initiator (I [I) has been proposed (Japanese Patent Publication No.
9-29849).

However, although the photosensitive resin composition described in Japanese Patent Publication No. 59-29849 has many advantages, compositions using such a copolymer still have some problems with the transparency and processability of the composition. It turned out that there was a point.

In addition, in the copolymers used in the photosensitive resin compositions, large amounts of photopolymerizable unsaturated monomers are used to increase sensitivity, and copolymers with a high degree of curing are used to increase the strength after curing. It has been found that the use of large amounts of functional unsaturated monomers significantly reduces the elasticity of the composition. In addition, when trying to increase the elasticity of the copolymer itself in order to increase the elasticity of the resin composition, the development time becomes extremely long when developing with an aqueous developer, and conversely, when trying to shorten the development time, carbon Acid component (α, β-ethylenically unsaturated carboxylic acid)
Increasing the glass transition temperature (Tg) of the polymer increases,
There are problems in that elasticity decreases and water resistance after photocuring decreases.

As a method for improving this, the present inventors have developed a conjugated diene component unit (A), an α,β-ethylenically unsaturated carboxylic acid component unit (B), a polyfunctional vinyl compound component unit (C), and a monoolefin-based proposed a photosensitive resin composition (JP-A-63-162612) containing a specific conjugated diene copolymer containing an unsaturated compound component unit (D) and having a defined intrinsic viscosity and glass transition point. However, it has been found that even with this method, the mechanical strength of the printing plate after photocuring is insufficient, and under severe usage conditions, relief defects may occur.

[Problem to be solved by the invention]

The present invention was made against the background of the above-mentioned problems of the prior art, and is developable with an aqueous developer, has excellent processability and photocurability, and has sufficient resistance to water-based inks after photocuring. It is an object of the present invention to provide a solid plate type photosensitive resin composition for flexographic printing, which has sufficient elasticity and flexibility to be used in flexographic printing, and has sufficient mechanical strength to withstand severe usage conditions. purpose.

[Means for Solving the Problems]] The present invention provides (1) a conjugated diene component unit (A) (hereinafter “(
A) 40 to 90 mol% of α
, 0.5 to 10 mol% of β-ethylenically unsaturated carboxylic acid component unit (B) (hereinafter sometimes referred to as "(B) component)", polyfunctional vinyl compound component unit (C) (hereinafter [(C
0.1 to 5 mol% of component )), and 0 to 59 mol% of monoolefinically unsaturated compound component unit (D)- (hereinafter sometimes referred to as "component (D)"). 50 to 90 parts by weight of a conjugated diene copolymer containing (II) conjugated diene component unit (A) in a proportion of 30 to 90 mol%
, α, β-ethylenically unsaturated carboxylic acid component unit)
A conjugated diene copolymer containing 0 to 30 mol% of the monoolefinically unsaturated compound component unit (D) and 5 to 70 mol% of the monoolefinically unsaturated compound component unit (D) and having a number average molecular weight of 5.000 to 100,000. Combined 10 to 50 parts by weight [However, (1)
+ (II) -100 parts by weight), (II[) photopolymerizable unsaturated monomer, (1) to (II)
10 to 200 parts by weight per 100 parts by weight of the total amount of ingredients,
and (IV) a photosensitive resin composition containing a photopolymerization initiator in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the total amount of components (N to ([r)).

The copolymer (1) of the present invention is a partially crosslinked polymer,
Examples of the conjugated diene monomer of the conjugated diene component unit (A) constituting this copolymer include (1), 3-butadiene, isoprene, chloroprene, and 1°3-pentadiene.

If the content of component (A) is less than 40 mol%, the rubber elasticity will be poor, and if it exceeds 90 mol%, the solid retention property, processability, and developability of the composition will be poor.

The preferred range is 50 to 85 mol%, more preferably 65 to 85 mol%.

The αβ-ethylenically unsaturated carboxylic acid monomer of the α,β-ethylenically unsaturated carboxylic acid component unit (B) constituting the copolymer (I) of the present invention includes acrylic acid, methacrylic acid, maleic acid, , fumaric acid, monoethyl maleate,
Examples include itaconic acid.

If the content of component (B) is less than 0.5 mol%, the alkali water solubility will be poor, and if it exceeds 10 mol%, the rubber elasticity and water resistance will be poor. The preferred range is 1 to 8 mol%.

Examples of the polyfunctional vinyl compound monomer of the polyfunctional vinyl compound component unit (C) constituting the copolymer (I) of the present invention include ethylene glycol dimethacrylate, ethylene glycol diacrylate, trimethylolpropane trimethacrylate, In addition to polyvalent acrylic acid esters such as propylene glycol dimethacrylate and propylene glycol diacrylate, divinylhenzene and trivinylbenzene may be mentioned.

If the content of component (C) is less than 0.1 mol%, transparency and processability will be poor, and if it exceeds 5 mol%, alkali water solubility and strength after photocuring will be poor. The preferred range is 0.5-3
It is mole%.

The monoolefinically unsaturated compound monomer of the monoolefinically unsaturated compound component unit (D) constituting the copolymer (I) of the present invention includes methyl acrylate, ethyl acrylate, n-butyl acrylate, α-ethyl In addition to acrylic acid esters represented by hexyl acrylate, n-octyl acrylate, dodecyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, cyanoethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, or these methacrylates,
Examples include styrene, acrylonitrile, vinylidene fluoride, and vinyl chloride, which may be used alone or in combination depending on the purpose.

The content of component (D) is 0 to 59.4 mol%, preferably 10 to 50 mol%, and if it exceeds 59.4 mol%, the rubber elasticity will be poor.

Incidentally, the Mooney viscosity of the copolymer (I) is preferably 3
0 to 2001, more preferably 60 to 150, and 3
If it is less than 0, the solidity of the composition will be poor;
When it exceeds 0, workability tends to decrease.

Next, the copolymer is a linear polymer, and the conjugated diene monomer of the conjugated diene component unit (A) constituting this copolymer is the same as that of the copolymer (I). and (
1) It may be the same as the component or different.

The content of component (A) is 30 to 90 mol%, and 3
If it is less than 0 mol%, water resistance and elasticity will be poor; on the other hand, if it is 90 mol%
Exceeding this decreases dissolution. Preferably it is 50 to 85 mol%.

As the α, β-ethylenically unsaturated carboxylic acid monomer of the α, β-ethylenically unsaturated carboxylic acid component unit constituting copolymer (II), the same one as in copolymer (1) is used. The components (N) and (N) may be the same or different. The content of component (B) is 0 to 30 mol%, and if it exceeds 30 mol%, elasticity and water resistance will decrease. Preferably it is 0 to 20 mol%.

As the monoolefinically unsaturated metal monomer of the monoolefinically unsaturated compound component unit constituting the copolymer (If), the same monoolefinically unsaturated metal monomer as in the copolymer (1) is used;
) may be the same as or different from the components. (
D) The content of component is 5 to 70 mol%, and 5 mol%
If it is less than 70 mol %, the processability will be poor, while if it exceeds 70 mol %, the amount of other components will be relatively too small, resulting in a decrease in elasticity and water developability. Preferably it is 10 to 50 mol%.

The number average molecule of copolymer (II) is 5.000 to 100
．． 000, and if it is less than 5,000, the effect of improving mechanical strength is not sufficient (on the other hand, if it exceeds 100,000, there is a significant deterioration in developability. Preferably, from 10,000 to so,
It's ooo.

The blend ratio (weight ratio) of copolymer (1) and copolymer (II) in the present invention is 50 to 90 parts by weight of (I),
Preferably 60 to 90 parts by weight, 50 to 10 parts by weight of (II), preferably 40 to 10 parts by weight [However, (I) +
(II) = 100 parts by weight], and the copolymer (II)
If it is less than 10 parts by weight, there is almost no effect of improving mechanical strength, while if it exceeds 50 parts by weight, the developability and elasticity are significantly reduced.

In the case of the copolymer (1), the monomers constituting each of the components (A) to (D) are added in a predetermined amount, for example, 40 to 90 mol% of the conjugated diene monomer (A), preferably 50 ~85 mol%, α, β-ethylenically unsaturated carboxylic acid monomer (B)
0.5 to 10 mol%, preferably 1 to 8 mol%, polyfunctional vinyl compound monomer (C) 0.1 to 5 mol%, preferably 0.5 to 4 mol%, and monoolefin monomer (C) Saturated compound monomer (D) 0 to 59.4 mol%, preferably 5
~40 mol% (However, (A) + (B) + (C) +
(D) = lOO mol%), and in the case of copolymer (II), a predetermined amount of the monomers constituting the components (A) to (B) and (D), e.g. Conjugated diene monomer (A) 30-90 mol%, preferably 50-8
5 mol%, αβ-ethylenically unsaturated carboxylic acid monomer (
B) 0 to 30 mol%, preferably 0 to 20 mol%, and monoolefinically unsaturated compound monomer (D) 5 to 70
mol%, preferably 10 to 50 mol% (however, (A)
+ (B) + (D) = l O0 mol %) by radical polymerization in an aqueous medium or an organic solvent, respectively.

A molecular weight regulator is used to adjust the molecular weight.

The amount used is 0.00 g per 100 g of monomer. 1-5g
is preferred. Each monomer and a polymerization agent such as a radical polymerization initiator may be added in their entirety to the reaction initiator, or may be added in arbitrary portions after the start of the reaction.

The polymerization is carried out at 0 to 50° C. in a reactor from which oxygen has been removed, but operating conditions such as temperature and stirring can be arbitrarily changed during the reaction.

The polymerization method can be either continuous or batchwise.

Examples of radical polymerization initiators include organic peroxides such as benzoyl peroxide, cumene hydroperoxide, paramethane hydroperoxide, and lauroyl peroxide, diazo compounds represented by azobisisobutyldinitrile, and inorganic peroxides represented by potassium persulfate. Redox catalysts such as organic peroxides and ferrous sulfate combinations are used. As the molecular weight regulator, t-dodecylmercaptan, dialkylxanthogen disulfide, etc. are used.

Copolymers (1) to (II) of the present invention are those in which residual double bonds derived from the conjugated diene monomer are three-dimensionally crosslinked by the action of actinic light such as ultraviolet rays and become insolubilized in solvents. When producing a photosensitive resin composition using the copolymer, a photopolymerizable unsaturated monomer (■) containing at least one ethylenically unsaturated group in the molecule, By adding the photopolymerization initiator (IV), the crosslinking reaction is promoted, and the mechanical strength of the printing plate etc. obtained after the crosslinking reaction is significantly improved.

Examples of the photopolymerizable unsaturated monomer (I) include unsaturated aromatic monomers such as styrene, α-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, diisopropenylbenzene, and divinylbenzene. compounds, unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, tart-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, 2-ethyl Acrylates or methacrylates of alkyl alcohols such as hexyl acrylate, n-octyl acrylate, n-decyl acrylate, lauryl acrylate; acrylates or methacrylates of hydroxyalkyl alcohols such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate or methacrylate; Acrylates or methacrylates of alkoxyalkylene glycols such as methoxyethylene glycol and methoxypropylene glycol, maleic acid, fumaric acid, maleic anhydride,
α,β-ethylenically unsaturated carboxylic acids such as crotonic acid, itaconic acid, itaconic anhydride, citraconic acid, and mesaconic acid; unsaturated polycarboxylic acids such as monoethyl maleate, monoethyl fumarate, and monoethyl itaconate; Esters, diesters such as dimethyl maleate, diethyl maleate, dibutyl maleate, dioctyl maleate, diethyl fumarate, dibutyl fumarate, dioctyl fumarate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, dioctyl itaconate , acrylamide, methacrylamide, acrylamide or methacrylamide such as N,N'-methylenebisacrylamide, N,N'-hexamethylenebisacrylamide, dimethylaminoethyl acrylate or methacrylate, diethylaminoethyl acrylate or methacrylate, dimethylaminopropylacrylamide or tertiary amino group-containing monomers such as methacrylamide, ethylene glycol diacrylate or dimethacrylate, polyalkylene glycol (
diacrylates or dimethacrylates of 2 to 23 alkylene glycols; diacrylates and triacrylates of polyhydric alcohols such as glycerin, pentaerythritol, trimethylolalkanes, and tetramethylolalkanes (alkanes include methane, ethane, and propane); , tetraacrylate or dimethacrylate, trimethacrylate or tetramethacrylate,
Examples include oligoacrylates. The photopolymerizable unsaturated monomer (TII) is used in an amount of 10 to 200 parts by weight based on 100 parts by weight of the total amount of copolymers (1) and (II) of the present invention.
The amount used is preferably 80 to 150 parts by weight, more preferably 20 to 100 parts by weight.

Within this range, two or more types can be used in combination. If the amount is less than 10 parts by weight, curing of the photosensitive resin layer and improvement in the mechanical strength of printing plates etc. cannot be expected sufficiently, and if it exceeds 200 parts by weight, the rubber elasticity of the copolymer will be significantly impaired and the solvent resistance will be It has drawbacks such as a decrease in

A photopolymerization initiator (
Examples of IV) include α-diketone compounds such as diacetyl and benzyl, airoins such as benzoin and bivaloin, and acyloin ethers such as benzoin methyl ether, benzoin ethyl ether, and benzoin propyl ether, which are usually used as photoreaction initiators. Examples include polynuclear quinones such as quinone, anthraquinone, and 1,4-naphthoquinone.

The amount of photopolymerization initiator (IV) added is determined by the amount of photopolymerization initiator (IV) added in the copolymer of the present invention (
1) and (1'l) sum! 0 per 100 parts by weight
．． The amount is 1 to 10 parts by weight, preferably 1 to 5 parts by weight. If it is less than 0.1 parts by weight, curing of the photosensitive resin layer will be insufficient, while if it exceeds 10 parts by weight, some of the added photoinitiator will not participate in the reaction, which is uneconomical. but sometimes the copolymer (1) of the present invention
- (II) or the photopolymerizable unsaturated monomer (I [I) may be poorly compatible and may be unevenly dispersed.

A small amount of a thermal polymerization inhibitor such as p-methoxyphenol is usually added to the commercially available photopolymerizable unsaturated monomer (III) described above, but this is necessary when exposing the photosensitive resin. It does not have any effect on the photosensitive resin composition, but rather acts as a storage stabilizer for the photosensitive resin composition. It can be added as is without being removed from the water.

Furthermore, the photosensitive resin composition of the present invention may optionally contain storage stabilizers such as hydroquinone, p-methoxyphenol, p-t-butylcatechol, 2,6-di-t-butyl-p-cresol, pyrogallol, etc. of hydroxyaromatic compounds, quinones such as benzoquinone, p-torquinone, and p-xyloquinone, and amines such as phenol-α-naphthylamine, based on 100 parts by weight of the total amount of copolymers (I) and (II). It can be added in an amount of .01 to 2 parts by weight.

A method for producing a letterpress using the photosensitive resin composition of the present invention is to add the photopolymerizable unsaturated monomer (■) and a photoinitiator (■) to a solution of copolymers (1) to (II). After adding an appropriate amount of (2) and stirring thoroughly to make a homogeneous solution, remove the solvent under reduced pressure while heating, or use a kneader, intermixer, etc. to mix solid copolymer (I) and copolymer. Combine (
II), a photopolymerizable unsaturated monomer (■), a photoinitiator (
TV) and kneading.

The photosensitive resin composition obtained in this way becomes a wax-like or rubber-like solid photosensitive resin composition with no fluidity, so it is necessary to sandwich a spacer with an appropriate thickness to maintain a constant film thickness. A photosensitive resin relief plate can be obtained by applying a negative film as a photosensitive resin layer of a constant thickness by coating it on a support with a roll coater or by compression molding, extrusion molding, etc., exposing it to light, and developing it.

The photosensitive resin composition is ideal for flexographic printing plates because it has high rubber elasticity, and a support that has the same degree of rubber elasticity as the photosensitive resin composition can be used as a support for supporting the resin layer. Examples include sheets made of natural rubber, styrene-butadiene rubber, butadiene rubber, acrylonitrile-butadiene rubber, isoprene rubber, ethylene-propylene rubber, crystalline 1,2-butadiene resin, soft vinyl chloride resin, etc., and supports with little rubber elasticity. Films of polyester, polypropylene, polystyrene, nylon, vinylidene chloride, polyethylene, etc. can also be used in areas where bodies can be used.

In addition, grained aluminum plates, iron plates, magnesium plates, etc. can also be used as supports for using photosensitive resins using the copolymer of the present invention in fields such as newspaper printing and general commercial printing. can.

One of the features of the present invention is the developability with a dilute aqueous alkali solution, but the alkali used may be any ordinary alkali, such as sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia, lithium carbonate, etc. 0.1~
A low concentration aqueous solution of about 1.0% by weight is used as a developer.

In addition, as a photopolymerizable unsaturated monomer to be blended, a monomer having a tertiary amine, such as dimethylaminoethyl acrylate or dimethylaminopropylacrylamide, reacts with the carboxylic acid in the copolymer to form an ammonium salt. Development using only water can be achieved by using the obtained tertiary amine-containing unsaturated monomer or by blending a low molecular weight compound containing a tertiary amino group such as dimethylaminoethanol, diethylaminoethanol, dimethylamine propatool, etc. is also possible.

Furthermore, the copolymer of the present invention can of course be developed not only with an alkaline aqueous solution but also with an organic solvent such as alcohol, ketone, or aromatic hydrocarbon.

The photosensitive resin composition obtained from the copolymer of the present invention has high photosensitivity and therefore requires a short exposure time, and has extremely good solubility in a dilute alkali aqueous solution and can be developed in 10 seconds to 2 minutes. Since printing can be performed immediately after drying, the complicated production process and production time of conventional rubber letterpress plates for flexographic printing can be significantly improved. In addition, it is possible to print with solvent-based flexographic inks, but even though they can be developed with water-based developers, water-based inks are increasingly being replaced by solvent-based flexographic inks due to air pollution concerns. Printing with flexo ink is possible.

The copolymer of the present invention can be used for newspapers, resin letterpress for general commercial printing,
For name plates, printed wiring, displays,
It can be widely used as a photosensitive material for photoadhesives, and can also be used as a vehicle for photocurable water-based and oil-based paints, inks, and adhesives that can be applied to flexible painted and adhesive surfaces. It is possible to provide a photosensitive resin composition that can.

[Effect]

In the copolymers (1) to (II) used in the present invention, when the conjugated diene monomer (A) is polymerized and incorporated into the copolymer, it is added to the main chain or side chain of the copolymer. Since double bonds remain, the photoreacted composition not only forms a strong three-dimensional network structure, but also enhances water resistance and solvent resistance, and furthermore, the conjugate contained in the copolymer The diene monomer provides the flexibility required for a flexographic printing plate, that is, rubber elasticity, and the α,β-ethylenically unsaturated carboxylic acid monomer (B) provides affinity for dilute aqueous alkaline solutions. The polyfunctional vinyl compound monomer (C) is used for the copolymer (1) of the present invention to increase, that is, satisfy the alkali developability or water developability,
The copolymer is partially crosslinked, thereby improving transparency and processability, and further improving water dispersibility. They each function to improve the mechanical properties of the printing plate, such as rubber elasticity, strength, and elongation, and to improve the printing properties of the printing plate, such as ink receptivity and ink transferability.

Further, in the present invention, the copolymer (1) is a partially crosslinked polymer, and when it is made into a photosensitive resin composition, it has the function of imparting solidity, 5 water developability, and elasticity to the printing plate after photocuring. On the other hand, copolymer (II) is a linear polymer, and each has the effect of improving mechanical properties such as strength and elongation, which were insufficient with copolymer (I) alone. , the present invention uses these two types of copolymers (1) to (H) together to improve water developability, water resistance, ink resistance,
Not only does it simultaneously satisfy the conflicting properties of high elasticity, but it also significantly improves the mechanical strength of the printing plate after photocuring, which was insufficient with only the partially crosslinked polymer copolymer (1). be.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

In addition, in the examples, the processability was determined by hot roll (4
0 to 120℃) and have poor wrapping properties.
Those that were highly sticky and difficult to process were rated as ×, and those that had no problems with roll wrapping or shrinkage were rated as ○. In addition, polymers with low molecular weights and unable to maintain solidity were also judged to have poor processability from the viewpoint of handling.

The development time is as follows:
The sheet was crimped onto a polyester sheet through a spacer to a thickness of one fin, and this sheet was cut into 20 x 201 pieces, and 40 pieces were cut using a nylon brush-equipped elution machine, JW-A4-5 (manufactured by JEOL Seiki ■). The development was carried out in warm water at a temperature of 0.degree. C., and the time required for the composition to completely dissolve was defined as the development time (seconds).

Anti-ta elasticity, hardness (JISA), tensile strength (
T8), elongation at break (El+) is JIS K2
Measured according to SO3.

Water resistance is determined by applying the photosensitive resin composition without passing through a negative film.
After exposing the entire surface to light for 0 seconds, the cured resin was coated with a diameter of 3.5cm+
It was punched out into a disk shape, immersed in a 001% by weight aqueous sodium carbonate solution whose temperature was adjusted to 40°C, and the degree of swelling (61%) was determined after 24 hours.

Ink transferability is determined by printing a resin letterpress plate created by exposure and development through a test negative film with black letterpress ink, and obtaining a print that is faithful to the original image on the paper surface after printing. Those in which thick lines or stains on the paper surface were observed due to blurring, missing parts, swelling of the plate, etc. were rated as "×".

Example 1 Synthesis of copolymer (1) Using the monomers and polymerization agents shown below, an internal volume of 20 I
! Polymerization was carried out at 30°C in an autoclave of
20 water
200 Sodium dodecylbenzenesulfonate 5 Potassium persulfate 0
．． Potassium trichloride 0.
1 When the polymerization rate reached 50%, 3 parts by weight of methacrylic acid and 2 parts by weight of ethylene glycol dimethacrylate were further added to continue the reaction, and the polymerization rate of all monomers added to the polymerization system was 90%. After reaching , monomer 10
Polymerization was stopped by adding 0.2 parts by weight of hydroxylamine sulfate per 0 parts by weight. Subsequently, the mixture was heated and residual monomers were removed by steam distillation.

The composition of the obtained copolymer (1) was determined using pyrolysis gas chromatography. The content of methacrylic acid was determined by dissolving the cocharger in dioxane and performing alkaline titration.

As a result, the molar composition of the obtained copolymer (1) was: butadiene/methacrylic acid/ethylene glycol dimethacrylate/ethyl acrylate=84.8/2.0/1.
It was 2/12.0.

Further, the obtained copolymer (1) had a Mooney viscosity of 85.

Copolymer (II) using the monomers and polymerization agents shown below,
) Polymerization was carried out in the same manner as in (1).

1 Lk no (knee (parts by weight)) Butadiene 70 Methacrylic acid 10 Ethyl acrylate
20 water
200 Sodium dodecylbenzenesulfonate 5 Potassium persulfate
0.3 potassium chloride
0. 1 Tertiary dodecyl mercaptan 3 When the polymerization rate reached 90%, 0.2 parts by weight of hydroxylamine sulfate was added per 100 parts by weight of monomer to stop the polymerization, and then heated and steamed. Residual monomers were removed by distillation.

The thus obtained copolymer (II) was analyzed in the same manner as copolymer (1), and the result was that the obtained copolymer (
The molar composition of II) is butadiene/methacrylic acid/ethyl acrylate = 81/7/12, number average molecular weight (Mn
)=18,000.

Copolymers (I) and (II) thus obtained
of latte lettuce at a polymer weight ratio of (1)/(II
) = 70/30, and then coagulated in a calcium chloride aqueous solution, and the resulting coagulated product was washed with water and vacuum-dried at 50°C to prepare a sample for evaluation.

Next, 100 g of the copolymer mixture, 10 g of nonaethylene glycol monoacrylate as the photopolymerizable unsaturated monomer (III), 20 g of tetraethylene glycol diacrylate, 10 g of dimethylaminopropylacrylamide, and 5 g of dimethylolpropane triacrylate.
, 2.0 g of benzoin isopropyl ether as a photoinitiator (IV), and 2.6-t as a storage stabilizer.
0.2 g of butylcatechol was placed in a pressure kneader with an internal volume of 250 m1, kneaded at 60°C for 30 minutes, and further kneaded on a hot roll (50°C) for 5 minutes to prepare a photosensitive resin composition. did.

15 g of the obtained photosensitive resin composition was placed on a styrene-butadiene rubber sheet (64 d, thickness 1.0 μl),
A photosensitive resin layer of 2.0 mm was produced using an applicator with a spacing of 2.0 mm.

The photosensitive resin layer maintained solidity and had no problems in handling.

Next, a negative film having an optical density of 3.5 was applied to the resin layer while maintaining a distance of 0.3 mm, and the resin layer was exposed to ultraviolet light for 60 seconds using a 250 W ultra-high pressure mercury lamp from 60 cm above the resin layer. When the exposed resin layer was developed in warm water at 40° C. for 1 minute using a nylon brush, the unexposed areas were completely dissolved and removed, making it possible to produce a resin letterpress faithful to the original image.

The resin plate has rubber elasticity, and the anti-In elasticity is 35%.
, rubber hardness (Shore A hardness, measured at 20°C) is 70, T,
l was 95 kgf10J, and E3 was 110%.

In addition, the entire surface was exposed to light for 60 seconds without using a negative film, and the resin layer was punched out into a disk shape with a diameter of 3.5, which was immersed in a 0.1% by weight aqueous sodium carbonate solution at 40°C for 24 hours. The degree of swelling after was measured was 0.5.
%Met.

When the resin letterpress plate was printed with black letterpress ink, printed matter with good ink transfer properties was obtained.

The results are shown in Table 1.

Example 2 Polymerization was carried out in the same manner as in Example 1 using butadiene/methacrylic acid/divinylbenzene/acrylonitrile (parts by weight) = 70/3/2/20 as copolymer (I), and the polymerization rate was 65. %, methacrylic acid/divinylbenzene (parts by weight) = 3/2 was further added to continue the reaction, and the polymerization rate of all monomers added to the polymerization system was 90%.
%, 0.2 parts by weight of hydroxylamine sulfate was added per 100 parts by weight of monomer to stop the polymerization. As a result, butadiene/methacrylic acid/divinylbenzene/acrylonitrile (molar ratio) -73/4.
Copolymer (1
)was gotten.

Copolymer (II) was prepared in the same manner as in Example 1, butadiene/methacrylic acid/acrylonitrile (molar ratio) = 70/
6.1/23.9, number average molecular weight (Mn) = 26.00
A copolymer of 0 was obtained.

Next, in the same manner as in Example 1, the copolymer (1)/copolymer (■) (weight ratio) was mixed in a Latinx state so that the weight ratio was 70/30, and the mixture was coagulated with an aqueous calcium chloride solution. A photosensitive resin composition was prepared and evaluated in the same manner as in Example 1.

The resin plate has rubber elasticity, and T is 80 kg f
/cj and EB were 100%.

The results are shown in Table 1.

Examples 1 and 2 were all good in processability, water resistance, and printability, and TB, E, and + were also sufficient as the strength of the printing plate.

Examples 3 to 6 In the same manner as Examples 1 to 2, the polymer composition, molecular weight, and copolymer (I)/(II) mixing ratio were varied. The results are shown in Table 1.

All exhibited excellent printability, developability, and printing plate strength.

Comparative Examples 1-4 Copolymers shown in Table 1 were prepared using the same polymerization recipe as Examples 1-2, and photosensitive resin compositions were prepared using the same formulations as Examples 1-2, and the same evaluations were conducted. I did it.

The results are shown in Table 1.

In an example in which the copolymer (If) of Comparative Example 1 was not blended,
There were no problems with elution, water resistance, printability, etc., but the strength was low and thin line parts were sometimes missing when handled.

As in Comparative Example 2, when the copolymer (I[) alone had a large amount of butadiene and a small amount of methacrylic acid, no total elution occurred, and the processability was poor and molding was difficult.

As in Comparative Example 3, when there is too much copolymer (I[), the dissolution properties, processability, and rebound properties are significantly reduced, and printability is also poor.

As in Comparative Example 4, when only copolymer (II) is used, the amount of butadiene is small, and the amount of methacrylic acid is large, elution is possible, but the glass transition temperature of the copolymer becomes high, resulting in This resulted in a significant decrease in anti-ta elasticity, an increase in hardness, and a decrease in water resistance, making it unsuitable for practical use.

(The following is a blank space) [Effects of the Invention] The photosensitive resin composition of the present invention exhibits good water or alkali developability, and the plate after photocuring has water resistance, solvent resistance,
As described above, it is possible to obtain a resin plate for flexographic printing that has excellent properties such as rubber elasticity, transparency, processability, and mechanical properties.

Patent applicant: Japan Synthetic Rubber Co., Ltd. Agent: Patent Attorney Takashi Shirai

Claims (1)

[Claims] (1) (I) 40 to 90 conjugated diene component units (A)
mol%, α,β-ethylenically unsaturated carboxylic acid component unit (B) 0.5 to 10 mol%, polyfunctional vinyl compound component unit (C) 0.1 to 5 mol%, and monoolefin system 0 to 59.4 mol% of unsaturated compound component unit (D)
Conjugated diene copolymer (I) containing in a proportion of 50 to
90 parts by weight, (II) 30 to 30 parts of conjugated diene component unit (A)
90 mol%, α,β-ethylenically unsaturated carboxylic acid component unit (B) in a proportion of 0 to 30 mol%, and monoolefinically unsaturated compound component unit (D) in a proportion of 5 to 70 mol%, and 10 to 50 parts by weight of a conjugated diene copolymer (II) having a number average molecular weight of 5,000 to 100,000 [However, (I) + (II)
= 100 parts by weight], (III) a photopolymerizable unsaturated monomer, 10 to 200 parts by weight per 100 parts by weight of the total amount of components (I) to (II), and (IV) a photopolymerization initiator. , 0.1 to 10 parts by weight based on 100 parts by weight of the total amount of components (I) to (II).