HK1087788A - Photosensitive resin composition, photosensitive layer therefrom and photosensitive resin printing original plate - Google Patents

Description

Photosensitive resin composition, photosensitive layer using the same, and original plate for photosensitive resin printing

Technical Field

The present invention relates to a photosensitive resin composition and a photosensitive resin printing original plate using the same, and more particularly, to a photosensitive resin composition for printing and a printing original plate which can be developed with an aqueous developer and are excellent in image reproducibility.

Background

Conventionally, there have been many reports on a photosensitive resin composition using an elastomer such as chlorinated rubber, a styrene-butadiene block copolymer, or polyurethane as a single resin component, and further, a photopolymerization initiator and an ethylenically unsaturated compound are blended to give the photosensitive resin composition a characteristic of an elastomer, and the photosensitive resin composition can be used as a flexographic printing plate material.

Among them, a phase structure in which particles having a phase 1 mainly composed of a hydrophobic polymer and a phase 2 mainly composed of a hydrophilic polymer are used as a dispersed phase and a phase having a hydrophilic component and a hydrophobic component is used as a continuous phase on a flexographic printing plate which can be developed with an aqueous developing solution and to which resistance to aqueous inks is imparted is proposed (see, for example, japanese unexamined patent application publication No. 03-136052).

However, since a solid rubber is used in the dispersed phase and the continuous phase in such a phase structure, fine particles aggregate at the phase structure formation stage, and as a result, the particle diameter of the dispersed phase tends to become large or uneven. This causes a problem that transmitted light is scattered and image reproducibility of the minute relief is deteriorated.

Therefore, there are documents (see, for example, japanese unexamined patent application publication nos. 2002-162731 and 2000-155417) which propose: in order to miniaturize the particle size of the dispersed phase, a hydrophilic copolymer synthesized by emulsion polymerization or a polymer obtained by dispersing a latex in water as the dispersed phase is dispersed in a hydrophilic photopolymerizable monomer.

However, in these methods, the dispersed phase is made into fine particles, but since solid rubber is used in most of the continuous phase, fine particles aggregate at the phase structure formation stage, and as a result, the particle size of the dispersed phase tends to become large or uneven. This causes a problem that transmitted light is scattered, and image reproducibility of the minute relief is deteriorated.

In view of the above problems, an object of the present invention is to provide a photosensitive resin composition and a photosensitive resin printing original plate which can be developed with an aqueous developer, have resistance to aqueous inks and cosolvent inks, and have excellent image reproducibility.

Disclosure of Invention

The present inventors have intensively and repeatedly studied to solve the above problems, and as a result, the present invention has been completed. That is, the present invention relates to: (1) a photosensitive resin composition comprising: (A) at least two or more hydrophobic polymers obtained from an aqueous dispersion latex, (B) a photopolymerizable compound, (C) a photopolymerization initiator; the photosensitive resin composition is characterized in that the two or more hydrophobic polymers are respectively present in the form of microparticles. (2) The photosensitive resin composition according to the above (1), wherein the fine particles of the component (A) have a particle size distribution in which two or more peaks are present, and the particle size ratio of each peak is 2 times or more. (3) The photosensitive resin composition according to the above (1), further comprising (D) a hydrophilic polymer. (4) The photosensitive resin composition according to the above (3), wherein at least one of the hydrophobic polymers of the component (A) and the hydrophilic polymer of the component (D) have a common skeleton structure. (5) The photosensitive resin composition according to the above (1), further comprising (E) a viscosity modifier. (6) The photosensitive resin composition according to the above (5), wherein the component (E) is a carboxylic acid copolymer. (7) The photosensitive resin composition according to the above (1), further comprising (F) an anti-aggregation agent. (8) The photosensitive resin composition according to the above (7), wherein the component (F) is a nonionic surfactant. (9) The photosensitive resin composition according to the above (1), further comprising (G) a conjugated diene oligomer having no crosslinking group. (10) The photosensitive resin composition according to the above (9), wherein the molecular weight of the component (G) is 500 to 10000. (11) The photosensitive resin composition according to any one of (1) to (10), wherein at least one of the components (B) is an alkyl methacrylate. (12) The photosensitive resin composition according to the above (11), wherein the alkyl methacrylate in the component (B) is linear having 8 to 18 carbon atoms. (13) A photosensitive resin composition layer obtained from the photosensitive resin composition according to the above (1), wherein the layer has a change rate of compression elasticity of 30% or less and a swelling rate of 16% or less before and after immersion in a cosolvent. (14) A photosensitive resin printing original plate, which is characterized by being formed by applying a photosensitive layer comprising the photosensitive resin composition according to any one of the above (1) to (13) on a support.

The use of the photosensitive resin composition of the present invention is useful in the industrial field because it can provide a flexographic printing original plate which can be developed with an aqueous developer, has resistance to aqueous inks, and has excellent image reproducibility.

The present invention will be described in detail below.

The aqueous dispersion latex used as the component (A) in the present invention is obtained by dispersing polymer particles as a dispersoid in water, and may further contain a surfactant and the like. The term "at least two or more hydrophobic polymers obtained from the water-dispersed latex" means a substance containing a hydrophobic polymer obtained by removing water from the water-dispersed latex, and some surfactants, etc., and in the present invention, two or more hydrophobic polymers are essentially used.

Specifically, the component (A) is a latex selected from at least two or more of the following, for example: water-dispersed latex polymers such as polybutadiene latex, natural rubber latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, polychloroprene latex, polyisoprene latex, polyurethane latex, methyl methacrylate-butadiene copolymer latex, vinylpyridine polymer latex, butyl polymer latex, polysulfide rubber latex, and acrylate polymer latex, or polymers obtained by copolymerizing these polymers with other components such as acrylic acid and methacrylic acid. Among them, water-dispersed latex polymers containing a butadiene skeleton or an isoprene skeleton in the molecular chain are preferably used from the viewpoint of hardness and rubber elasticity. Specifically, polybutadiene latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, and polyisoprene latex are preferable.

The component (a) in the present invention is required to be present in the form of fine particles, and two or more peaks in the particle size distribution thereof have a particle size ratio of 2 times or more, particularly a lower limit of about 3 times or more, more preferably 5 times or more, and an upper limit of about 20 times or less, more preferably 15 times or less. The term "exist in the form of fine particles" means that the existence of independent fine particles can be confirmed by performing morphological observation and phase distribution evaluation using, for example, a scanning probe microscope SPM.

The particle size distribution may be the distribution of the same kind of hydrophobic polymer, or two or more kinds of hydrophobic polymers may have one peak in the particle size distribution, but the particle size ratio of each peak may be 2 times or more. In the present invention, it is preferable that another kind of fine particles having an average particle diameter of about 2 times or more is present with respect to the average particle diameter of one kind of fine particles, and as the average particle diameter, for example, the hydrophobic polymer (α) is 0.02 to 0.5 μm, preferably 0.04 to 0.3 μm, and the hydrophobic polymer (β) is 2 times or more, particularly preferably 3 times or more, of the hydrophobic polymer (α), and the particle diameter is 0.1 to 0.7 μm, preferably 0.2 to 0.5 μm.

The fine particles of component (a) are preferably dispersed in the photopolymerizable compound of component (B) and the photopolymerization initiator of component (C).

The photopolymerizable compound of component (B) in the present invention is preferably a photopolymerizable oligomer, and the photopolymerizable oligomer is a polymer in which an ethylenically unsaturated group is bonded to a terminal and/or a side chain of a conjugated diene polymer, and has a number average molecular weight of 1000 or more and 10000 or less. Specifically, the term "a compound having the following structure in its molecular structure" means a compound having the following structure.

The conjugated diene polymer constituting the conjugated diene ethylenic polymer is composed of a single polymer of a conjugated diene unsaturated compound or a copolymer of a conjugated diene unsaturated compound and a monoethylenically unsaturated compound. Specific examples of such a single polymer of a conjugated diene unsaturated compound or a copolymer of a conjugated diene unsaturated compound and a monoethylenically unsaturated compound are: butadiene polymers, isoprene polymers, chloroprene polymers, styrene-chloroprene copolymers, acrylonitrile-butadiene copolymers, acrylonitrile-isoprene copolymers, methyl methacrylate-chloroprene copolymers, methyl acrylate-butadiene copolymers, methyl acrylate-isoprene copolymers, methyl acrylate-chloroprene copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-chloroprene-styrene copolymers, and the like. Among them, from the viewpoint of rubber elasticity and photocurability, butadiene polymers, isoprene polymers, and acrylonitrile-butadiene copolymers are preferable, and butadiene polymers and isoprene polymers are particularly preferable.

The method for introducing the terminal and/or side chain ethylenic unsaturated group of the conjugated diene polymer is not particularly limited, and examples thereof include: (1) a method in which a terminal hydroxyl group of a hydroxyl-terminal conjugated diene polymer obtained using hydrogen peroxide as a polymerization initiator is subjected to a dehydration reaction with a monoethylenically unsaturated carboxylic acid such as (meth) acrylic acid to form an ester linkage, or an ester exchange reaction is performed with a monoethylenically unsaturated carboxylic acid alkyl ester such as methyl (meth) acrylate or ethyl (meth) acrylate to form an ester linkage; (2) and a method of reacting a conjugated diene polymer obtained by copolymerizing a conjugated diene compound and an ethylenically unsaturated compound containing at least a part of an unsaturated carboxylic acid (ester) with an ethylenically unsaturated alcohol such as allyl alcohol or vinyl alcohol.

The amount of the ethylenically unsaturated group in the conjugated diene-based ethylenic polymer is preferably 0.005 to 2.0m equivalents/g, particularly preferably 0.01 to 2.0m equivalents/g, in the polymer. If the content is more than 2.0m equivalent/g, the hardness is too high and sufficient elasticity is difficult to obtain, while if the content is less than 0.005m equivalent/g, the reactivity tends to be low and the image reproducibility tends to be low.

The content of the component (B) is preferably 1 to 200 parts by weight based on 100 parts by weight of the component (A). When the amount is 1 part by weight or less, the plate becomes hard and thus cannot be developed with an aqueous developing solution, and when the amount is 200 parts by weight or more, the plate becomes too soft and the workability is deteriorated, which is not preferable.

In the present invention, in order to improve the mechanical strength of the printing plate and improve the printing resistance, it is preferable that at least one of the components (B) other than the above is an alkyl methacrylate. The alkyl methacrylate is particularly preferably linear having 8 to 18 carbon atoms.

Specific examples include: alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate; cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate; halogenated alkyl (meth) acrylates such as chloroethyl (meth) acrylate and chloropropyl (meth) acrylate; alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, and butoxyethyl (meth) acrylate; and phenoxyalkyl (meth) acrylates such as phenoxyethyl (meth) acrylate and nonylphenoxyethyl (meth) acrylate. Particularly preferred are n-lauryl methacrylate, alkyl (C12-13) methacrylate, tridecyl methacrylate, alkyl (C12-15) methacrylate, and the like.

The content of these alkyl methacrylates is preferably 1 to 50 parts by weight, and particularly preferably 5 to 10 parts by weight, based on 100 parts by weight of the component (A). When the amount is less than 1 part by weight, the mechanical strength of the plate to be exposed is insufficient, and when the amount exceeds 50 parts by weight, the plate is leached out on the surface of the photosensitive resin composition layer, and the film is difficult to peel, which is not preferable.

In addition, a photopolymerization initiator is added as the component (C) to the photosensitive resin composition of the present invention. The photopolymerization initiator may be any one that can polymerize a polymerizable carbon-carbon unsaturated group by light. Among them, a substance having a function of generating radicals by self-decomposition or hydrogen elimination by light absorption is preferably used. Examples include: benzoin alkyl ethers, benzophenones, anthraquinones, benzils, acetophenones, butanediones, and the like. The amount of the photopolymerization initiator is preferably in the range of 0.1 to 50 parts by weight per 100 parts by weight of the component (A). When the amount is 0.1 parts by weight or more, the initiation efficiency is not reduced and the image reproducibility is good, and when the amount is 50 parts by weight or less, the sensitivity is not excessively high and the exposure time is easily controlled, and therefore, it is preferably used.

In the present invention, a hydrophilic polymer may be incorporated as the component (D) if necessary, and the hydrophilic polymer preferably hasHaving the group-COOH, -COOM (M is a metal ion having a valence of 1, 2 or 3 or a substituted or unsubstituted ammonium ion), -OH, -NH₂、-SO₃H. Examples of the hydrophilic group such as a phosphate group include: a polymer of (meth) acrylic acid or a salt thereof, (a copolymer of (meth) acrylic acid or a salt thereof and an alkyl (meth) acrylate, (a copolymer of (meth) acrylic acid or a salt thereof and styrene, (a copolymer of (meth) acrylic acid or a salt thereof and vinyl acetate, (a copolymer of (meth) acrylic acid or a salt thereof and acrylonitrile, polyvinyl alcohol, carboxymethyl cellulose, polyacrylamide, hydroxyethyl cellulose, polyethylene oxide, polyethylenimine, polyurethane having a-COOM group, polyurethane urea having a-COOM group, polyamic acid having a-COOM group, and a salt or derivative thereof. These may be used alone or in combination of two or more.

The content of the component (D) is preferably 0.1 to 50 parts by weight, particularly preferably 0.1 to 30 parts by weight, based on 100 parts by weight of the component (A). When the amount is less than 0.1 part by weight, the development time of the aqueous developer is slow, and when the amount exceeds 50 parts by weight, water swelling increases and the resistance of the aqueous ink is deteriorated, which is not preferable.

In the present invention, when the hydrophilic polymer of the component (D) is blended, it is preferable that at least one of the hydrophobic polymers (α) or (β) in the component (a) and the hydrophilic polymers of the component (D) have a common skeleton structure, and examples of the common skeleton structure include: acrylonitrile-butadiene structure, and the like. In the present invention, a preferable structure is, for example, that the hydrophobic polymer (β) in the form of fine particles is present in the continuous phase, and the hydrophilic polymer and the hydrophobic polymer (α) in the form of fine particles having a common skeleton structure are present in the dispersed phase.

In the present invention, the viscosity modifier as the component (E) thickens the blended stock solution and prevents the stock solution from warping in the thickener. The viscosity modifier is preferably a carboxylic acid copolymer, and the types include: powder, aqueous solution, emulsion, and inverse emulsion, wherein emulsion is preferred. Typical commercially available products include, for example, the following: ァロン A-7070, ァロン A-7050, ァロン B-300, ァロン B-500, ァロン B-700 (synthesized in east Asia), etc., but are not limited thereto. These may be used alone or in combination of two or more. The amount of the viscosity modifier is preferably 0.1 to 10 parts by weight, particularly preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the component (A). When the amount is 0.1 part by weight or less, the viscosity of the stock solution is insufficient, and the stock solution may boil during concentration, and when the amount exceeds 10 parts by weight, swelling of the relief becomes large with respect to water and alcohol, which is not preferable. The viscosity of the stock solution obtained is preferably 15 poise or more, and particularly preferably 18 poise or more.

In the present invention, the anti-coagulation agent of component (F) is used for preventing rapid coagulation and solid-liquid separation between latex particles caused during the preparation of the stock solution. The anti-coagulation agent is preferably a nonionic surfactant, and particularly preferably a substance having 12 to 15 carbon atoms and an HLB value of about 12. Specifically, examples of the hydrophilic group in the molecular structure include: polyoxyalkylene chain structures such as polyoxyethylene, polyoxymethylene and polyoxypropylene. Examples of the type of the hydrophobic group in the molecular structure are: nonylphenols, tridecanols, lauryl alcohols, secondary alcohols, oxo alcohols, and the like. Typical commercially available products include, for example, the following: ノィゲン EA-120, ノィゲン EA-120B, DKS NL-70, DKS NL-80, ノィゲン ET-143L, ノィゲン TDS-70, ノィゲン ET-115, ノィゲン ET-116B, ノィゲン ET-116B, ノィゲン ET-116C, ノィゲン ET-147, ノィゲン ET-157, ノィゲン SD-60, ノィゲン SDX-60, DKS NL-Dash408, DKS NL-Dash 410 (first Industrial pharmaceutical Co., Ltd.), etc., but not limited thereto. These may be used alone or in combination of two or more. The amount of the anti-aggregation agent is preferably in the range of 0.01 to 10 parts by weight, and particularly preferably 0.1 to 1 part by weight, based on 100 parts by weight of the component (A). When the amount is 0.01 parts by weight or less, the effect of preventing rapid aggregation between latex particles and solid-liquid separation after charging the hydrophilic polymer is not sufficient, and when the amount exceeds 10 parts by weight, swelling of the relief with water and alcohol becomes large, which is not preferable.

In the present invention, the conjugated diene oligomer having no crosslinking group as the component (G) is used for reducing the crosslinking density of the photosensitive resin composition layer, adjusting the absorption of the cosolvent and the extraction of the oligomer component, which are caused when printing is performed using a cosolvent ink, and reducing the rate of change in apparent weight. The conjugated diene oligomer having no crosslinking group is preferably a conjugated diene oligomer having at least a 1, 2-butadiene skeleton and no crosslinking group. The molecular weight of the conjugated diene oligomer having a 1, 2-butadiene skeleton and no crosslinking group is preferably in the range of 500 to 10000, more preferably 1000 to 5000, and particularly preferably 1000 to 4000. Since when the molecular weight is less than 500, not only the workability of the resin plate deteriorates, but also there is a problem that the strength of the plate is impaired due to the oligomer component being largely extracted by the co-solvent contained in the co-solvent ink; or the hardness of the plate changes due to repetition of printing, and the surface smoothness of the printed matter changes, which is not preferable. When the molecular weight exceeds 10000, the rate of change in weight after impregnation with a desired cosolvent cannot be reduced, and the compatibility with the photosensitive resin composition is impaired, which is not preferable.

Specific examples of the conjugated diene oligomer having a 1, 2-butadiene skeleton include: polybutadiene oligomer without a terminal functional group, polystyrene-butadiene oligomer, polyacrylonitrile-butadiene oligomer, polyisoprene oligomer, polychloroprene oligomer, polybutadiene oligomer having a terminal allyl group, polystyrene-butadiene oligomer having a terminal allyl group, polyacrylonitrile-butadiene oligomer having a terminal allyl group, polyisoprene oligomer having a terminal allyl group, polychloroprene oligomer having a terminal allyl group, polybutadiene oligomer having a terminal hydroxyl group, polystyrene-butadiene oligomer having a terminal hydroxyl group, polyacrylonitrile-butadiene oligomer having a terminal hydroxyl group, polyisoprene oligomer having a terminal hydroxyl group, polychloroprene oligomer having a terminal hydroxyl group, polybutadiene oligomer having a terminal carboxyl group, polystyrene-butadiene oligomer having a terminal carboxyl group, polybutadiene oligomer having a terminal allyl group, and, Carboxyl-terminal-group-containing polyacrylonitrile-butadiene oligomer, carboxyl-terminal-group-containing polyisoprene oligomer, carboxyl-terminal-group-containing polychloroprene oligomer, amino-terminal-group-containing polybutadiene oligomer, amino-terminal-group-containing polystyrene-butadiene oligomer, amino-terminal-group-containing polyacrylonitrile-butadiene oligomer, amino-terminal-group-containing polyisoprene oligomer, amino-terminal-group-containing polychloroprene oligomer, and the like.

The content of the component (G) is 1 to 200 parts by weight, preferably 3 to 100 parts by weight, and more preferably 5 to 30 parts by weight based on 100 parts by weight of the component (A). When the amount is less than 1 part by weight, the plate becomes hard and thus cannot be developed with an aqueous developing solution, and when the amount exceeds 200 parts by weight, the plate becomes too soft and the workability is deteriorated, which is not preferable.

The photosensitive resin composition of the present invention may further contain a plasticizer. The plasticizer is not particularly limited as long as it is generally a material having a property of softening the printing plate, but is preferably a material having good compatibility with the components (A) and (D). More preferred are a polyene compound and a compound having an ester linkage which are liquid at room temperature. Examples of the polyene compound which is liquid at room temperature include: liquid polybutadiene, polyisoprene, maleic acid compounds obtained by further modifying the terminal group or side chain of these compounds, epoxides and the like. Examples of the compound having an ester linkage include: phthalate, phosphate, sebacate, adipate, polyester with the molecular weight of 1000-3000 and the like.

When these plasticizer components are added, the amount of the plasticizer components added is preferably 0 to 100 parts by weight based on 100 parts by weight of the component (a) in order to obtain sufficient strength as a solid plate before photocrosslinking.

In order to improve the thermal stability of the photosensitive resin composition of the present invention, a conventionally known polymerization inhibitor may be added. Preferred polymerization inhibitors are, for example: phenols, p-phenylenediols, catechols, and the like. The amount of these components is generally in the range of 0.001 to 5% by weight based on the total weight of the photosensitive resin composition.

Further, as other components, dyes, pigments, antifoaming agents, ultraviolet absorbers, perfumes, and the like may be added.

The photosensitive layer obtained from the photosensitive resin composition of the present invention having such a structure preferably has a change rate of compression elasticity of 30% or less and a swelling rate of 16% or less before and after the immersion in the cosolvent, and the compression elasticity is a load required when the displacement after the intrusion of an iron rod having a diameter of 10mm is measured to be 0.1mm by テンシロン compression test. The co-solvent swelling ratio is a value obtained by measuring the weight change ratio after immersing in a co-solvent for 24 hours. The cosolvent used was a mixture of isopropyl alcohol and n-propyl acetate in a weight ratio of 8: 2, which was blended in a common cosolvent ink.

In the method for measuring the compression elasticity and swelling ratio in the present invention, specifically, in a photosensitive printing original plate having a square shape of 50mm, when a protective film, a slip coat layer, or the like is provided on a photosensitive resin composition layer, the photosensitive resin composition layer is peeled off and removed, and the whole surface is irradiated with active light, and the compression elasticity and weight before and after immersion in a cosolvent are measured to calculate the rate of change.

In the present invention, the rate of change in compression elasticity before and after immersion in the cosolvent is preferably 30% or less, more preferably 25% or less, and still more preferably 20% or less, and thus the printing durability in long-term printing when the cosolvent ink is used is excellent.

In order to maintain the accuracy as a printing plate, the photosensitive resin composition of the present invention may be provided with a support such as polyester on the opposite side of the relief. Since the photosensitive resin composition of the present invention is composed of the above-mentioned components, a flexible film layer which can be developed by water can be provided on the surface thereof so that the contact property of the transparent picture carrier (negative film) superimposed thereon is good and the image carrier can be reused. The photosensitive resin composition of the present invention can be produced by mixing the respective components. The method may be to mix the resin composition in an extruder, a kneader or the like, and then to form a layer having a desired thickness by hot press molding, calender treatment or extrusion molding. The support and the flexible film layer may be laminated and bonded to the photosensitive layer by a roller after the sheet is formed. The photosensitive layer with good precision can be obtained by hot pressing after lamination. Examples of the active light source used for photocuring the photosensitive resin composition of the present invention include: low pressure mercury lamps, high pressure mercury lamps, ultraviolet fluorescent lamps, carbon arc lamps, xenon lamps, zirconium lamps, sunlight, and the like. In the photosensitive resin composition of the present invention, after an image is formed by light irradiation through a transparent image support, the non-irradiated portion is removed (developed) with an aqueous developing solution, whereby a relief (printing plate) can be obtained.

The aqueous developer of the present invention is prepared by mixing a surfactant such as a nonionic surfactant or an anionic surfactant, and if necessary, a pH adjuster, a cleaning accelerator, and the like in water. Specific examples of the nonionic surfactant include: polyoxyalkylene alkyl or alkenyl ethers, polyoxyalkylene alkyl or alkenyl phenyl ethers, polyoxyalkylene alkyl or alkenyl amines, polyoxyalkylene alkyl or alkenyl amides, oxyethylene/oxypropylene block adducts, and the like. Specific examples of the anionic surfactant include: linear alkylbenzene sulfonate having an alkyl group with an average carbon number of 8 to 16, alpha-olefin sulfonate having an average carbon number of 10 to 20, dialkyl sulfosuccinate having an alkyl group or an alkenyl group with a carbon number of 4 to 10, sulfonate of fatty acid lower alkyl ester, alkyl sulfate having an average carbon number of 10 to 20, linear or branched alkyl group or alkenyl group having an average carbon number of 10 to 20, alkyl ether sulfate having an average addition of 0.5 to 8 moles of ethylene oxide, saturated or unsaturated fatty acid salt having an average carbon number of 10 to 22, and the like.

Specific examples of the pH adjuster include: sodium borate, sodium carbonate, sodium silicate, sodium metasilicate, sodium succinate, sodium acetate, and the like. From the viewpoint of being readily soluble in water, sodium silicate is preferred. Further, there is a cleaning assistant which can improve the cleaning ability by using the surfactant and the pH adjuster in combination. Specific examples include: amines such as monoethanolamine, diethanolamine, and triethanolamine; ammonium salts such as tetramethylammonium hydroxide; paraffin hydrocarbons, and the like. These are added in an appropriate mixing ratio in the range of 0.1 to 50% by weight, preferably 1 to 10% by weight, and mixed in water for use. After development, the plate is typically dried in an oven at about 60 ℃ for 15 to 120 minutes.

The photosensitive resin composition of the present invention may have a sticky residue on the plate surface after drying, depending on the composition. In this case, the sticky matter can be removed by a known surface treatment method. The surface treatment method is preferably an exposure treatment by an active light having a wavelength of 300nm or less.

The photosensitive resin composition of the present invention is most suitable for flexographic printing, and can be used as a resin relief printing, a lithographic printing, a gravure printing, a stencil printing, or a photoresist film.

Examples

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited thereto.

The characteristic values of the examples are values obtained by the following measurement methods.

(1) Measurement of average particle diameter of microparticles:

A) preparation of a sample: the obtained original plate for photosensitive resin printing was exposed to light at 10 minutes per surface and back using a chemical lamp (manufactured by a & V, ランプ, philips 10R), the coating and the anti-blocking layer were peeled off, the cured photosensitive layer was cut into sheets in a frozen state using a microtome, and the sheets were dried and then evaluated for the surface and internal structure of the sheets using a scanning probe microscope SPM.

The SPM used SPA300 (available from Seiko Instruments, SPI3800N system). The measurement mode was the DFM mode, and DF3 was used in the cantilever method. Morphological observation was performed in the DFM mode, and phase image observation was performed at the same time.

B) Measurement of particle size: the phase difference image was automatically binarized by the TOKS method using an image processing apparatus ィメ - ジァナラィザ -V20 manufactured by toyo textile co.

(2) Hardness: a value measured at 20 ℃ by a spring type hardness test (type A) method in accordance with JIS-K6301.

(3) Recovery elastic modulus: a steel ball of phi 10m/m (weight: 4.16g) was dropped from a height of 20cm from the ground, and the high position (a) of the rebound was read and expressed as (a/20) × 100%.

(4) Swelling ratio: the printing plate was immersed in water or ethanol, and the weight increase (%) after immersion at 20 ℃ for 1 hour or 24 hours was measured.

(5) Co-solvent swelling ratio: the printing plate was immersed in a cosolvent (isopropanol/n-propyl acetate 8/2) and the weight gain (%) after immersion for 24 hours at 20 ℃ was measured.

(6) Light scattering ratio: the scattering ratio of the photosensitive resin composition at λ of 365nm was measured by a spectrophotometer (U-3210, manufactured by Hitachi, Co., Ltd., with a 150 Φ integrating sphere attached device).

(7) Tensile product: the printing plate mold was extracted, and the elongation and strength measured by テンシロン (クロスヘッド 100kg was used) tensile test were multiplied to obtain a value.

(8) Stock solution viscosity: the viscosity of the blended stock solution was measured at 20 ℃ with a vibratile viscometer (VM-IC-MH, manufactured by CBC マテリァルズ Co., Ltd.).

(9) Compression elasticity: a printing plate was subjected to a compression test of テンシロン, and the load required when the displacement of an iron rod having a diameter of 10mm after being pushed in was 0.1mm was measured. The measurement was carried out in the same manner after immersing the sample in a cosolvent (isopropyl alcohol/n-propyl acetate: 8/2) at 20 ℃ for 24 hours.

(example 1)

A hydrophobic polymer (alpha) of component (A): acrylonitrile-butadiene latex (Nipol SX1503 non-volatile content 42% manufactured by Nippon ゼォン Co., Ltd.) 10 parts by weight, hydrophobic polymer (. beta.): butadiene latex (Nipol LX111NF nonvolatile content 55% manufactured by Nippon ゼォン Co., Ltd.) 58 parts by weight, oligobutadiene acrylate (ABU-2S manufactured by Kyoho chemical Co., Ltd.) 28 parts by weight as component (B), lauryl methacrylate (ラィトェステル L manufactured by Kyoho chemical Co., Ltd.) 4 parts by weight, dimethylol tricyclodecane diacrylate 4 parts by weight, photopolymerization initiator 1 part by weight as component (C), hydroquinone monomethyl ether 0.1 part by weight as a polymerization inhibitor, nonionic surfactant 0.1 part by weight as other additive, and toluene 15 parts by weight were mixed together in a container, kneaded at 105 parts by a pressure kneader, and then toluene and water were removed under reduced pressure, thereby obtaining a photosensitive resin composition.

Then, the obtained photosensitive resin composition was sandwiched between a film obtained by coating a polyester adhesive layer on a polyethylene terephthalate film having a thickness of 125 μm and a film similarly coated with an anti-blocking layer (polyvinyl alcohol) (the adhesive layer and the anti-blocking layer were brought into contact with the photosensitive resin composition), and the resultant was heated at 105 ℃ and 100kg/cm by a hot press²The pressure was applied for 1 minute, thereby obtaining a photosensitive resin original plate having a thickness of 1.7 mm. When the particle size distribution and the average particle size of the hydrophobic polymer fine particles in the photosensitive resin layer of the photosensitive resin original plate were measured by the above-described method, the particle size distribution had two peaks of 0.115 μm and 0.370 μm, and the particle size ratio was about 3 times.

Stripping the obtained original plate, setting the dot 200 line 1% -95%, the minimum independent dot diameter 100 μm, the minimum raised character 1 dot, the minimum reversed white character 1 dot, the solid image, the inspection negative film containing the procedure description, and using the 365nm illumination intensity of 17.5W/m²(Anderson&ランプ FR20T12-BL-9-BP manufactured by Vrieland corporation) was subjected to back exposure and surface exposure, the negative film was removed, developed with neutral water containing 4 wt% of sodium alkylnaphthalenesulfonate at 40 ℃ for 8 minutes, and dried at 60 ℃ for 10 minutes.

The obtained printing plate has a relief depth of 0.8mm, and can obtain image reproducibility which cannot be realized by the conventional flexographic printing plate by printing with aqueous ink, namely, can reproduce dot 200 lines of 1-95%, minimum independent dot diameter of 100 mu m, minimum independent line width of 30 mu m, minimum reversed white line width of 100 mu m, minimum raised character 1 dot and minimum reversed white character 1 dot. In addition, no change in image reproducibility was observed when 100 ten thousand printing tests were performed on the same printing plate. The resulting printing plate had a shore a hardness of 58, a recovery elasticity of 65%, a water swelling rate after 24 hours of 3.1%, an ethanol swelling rate of 5.0%, a light scattering rate at 365nm of 10.9%, and a tensile product of 260 (elongation 1.14 × strength 229).

(example 2)

A hydrophobic polymer (alpha) of component (A): acrylonitrile-butadiene latex (Nipol SX1503 non-volatile content 42% manufactured by japan ゼォン co., ltd.) 10 parts by weight, hydrophobic polymer (β): 62 parts by weight of butadiene latex (Nipol LX111NF nonvolatile matter 55% manufactured by Japan ゼォン Co., Ltd.); (B) component (A) Low polybutadiene acrylate (manufactured by ABU-2S Kyoeisha chemical Co., Ltd.) 30 parts by weight, lauryl methacrylate (manufactured by ラィトェステル L Kyoeisha chemical Co., Ltd.) 4 parts by weight, and dimethylol tricyclodecane diacrylate 4 parts by weight; (C) component (b) photopolymerization initiator 1 part by weight; (D) component (PFT-3 non-volatile component 25% Kyoeisha chemical Co., Ltd.) 18 parts by weight; 0.1 part by weight of hydroquinone monomethyl ether serving as a polymerization inhibitor; 0.1 part by weight of nonionic surfactant as another additive was mixed with 15 parts by weight of toluene in a vessel, kneaded at 105 parts by pressure kneader, and then toluene and water were removed under reduced pressure to obtain a photosensitive resin composition.

Then, the obtained photosensitive resin composition was sandwiched between a film obtained by coating a polyester-based adhesive layer on a polyethylene terephthalate film having a thickness of 125 μm and a film obtained by coating an anti-blocking layer (polyvinyl alcohol) on the same polyethylene terephthalate film (the adhesive layer and the anti-blocking layer were brought into contact with the photosensitive resin composition), and the resultant was heated at 105 ℃ and 100kg/cm by a hot press²The pressure was applied for 1 minute to obtain a photosensitive resin original plate having a thickness of 1.7 mm. Need to make sure thatThe particle size distribution and the average particle size of the hydrophobic polymer fine particles in the photosensitive resin of the photosensitive resin original plate were measured by the above-mentioned methods, and as a result, two peaks of 0.115 μm and 0.370 μm were observed in the particle size distribution, and the particle size ratio was about 3 times.

Stripping the obtained original plate, setting the dot 200 line 1% -95%, the minimum independent dot diameter 100 μm, the minimum raised character 1 dot, the minimum reversed white character 1 dot, the solid image, the inspection negative film containing the procedure description, and using the 365nm illumination intensity of 17.5W/m²(Anderson&ランプ FR20T12-BL-9-BP manufactured by Vrieland corporation) was subjected to back exposure and surface exposure, the negative film was removed, developed with neutral water containing 4 wt% of sodium alkylnaphthalenesulfonate at 40 ℃ for 8 minutes, and dried at 60 ℃ for 10 minutes to obtain a printing plate.

The obtained printing plate has a relief depth of 0.8mm, and can obtain image reproducibility which cannot be realized by the conventional flexographic printing plate by printing with aqueous ink, namely, can reproduce dot 200 lines of 1-95%, minimum independent dot diameter of 100 mu m, minimum independent line width of 30 mu m, minimum reversed white line width of 100 mu m, minimum raised character 1 dot and minimum reversed white character 1 dot. In addition, the image reproducibility of 100 ten thousand printing experiments performed on the same printing plate did not change. The resulting printing plate had a shore a hardness of 63, a recovery elasticity of 60%, a water swelling rate after 24 hours of 5.5%, an ethanol swelling rate of 5.0%, a light scattering rate at 365nm of 15.5%, and a tensile product of 280 (elongation 1.19 × strength 235).

(example 3)

A butadiene latex (Nipol LX111NF nonvolatile content 55% manufactured by Nippon ゼォン Co., Ltd.) 62 parts by weight and an acrylonitrile-butadiene latex (Nipol SX1503 nonvolatile content 43% manufactured by Nippon ゼォン Co., Ltd.) 10 parts by weight were used as the component (A); 30 parts by weight of an oligobutadieneacrylate (ABU-2S, chemical Co., Ltd.) as component (B); 0.45 part by weight of a photopolymerization initiator as the component (C); 18 parts by weight of a hydrophilic polymer (PFT-3 nonvolatile matter, 25% Co., Ltd.) as the component (D); viscosity modifier (ァロ) as component (E)ン A-7050 manufactured by Toyo Synthesis Co., Ltd.) in an amount of 1 part by weight; 4 parts by weight of lauryl methacrylate and 4 parts by weight of dimethylol tricyclodecane diacrylate as a crosslinking agent; 0.03 part by weight of hydroquinone monomethyl ether as a polymerization inhibitor; 0.04 parts by weight of a carboxylic acid copolymer as another additive was mixed with 15 parts by weight of toluene in a vessel, and the stock solution viscosity was measured. Then kneaded at 105 with a pressure kneader, and then toluene and water were removed by reduced pressure. The obtained photosensitive resin composition was sandwiched between a film obtained by coating a polyester-based adhesive layer on a polyethylene terephthalate film having a thickness of 125 μm and a film obtained by coating an anti-blocking layer (polyvinyl alcohol) on the same polyethylene terephthalate film (the adhesive layer and the anti-blocking layer were brought into contact with the photosensitive resin composition), and the resultant was heated at 105 ℃ and 100kg/cm by a hot press²The pressure was applied for 1 minute, thereby obtaining a photosensitive resin original plate having a thickness of 1.7 mm. Stripping the obtained original plate, setting the dot 200 line 1% -95%, the minimum independent dot diameter 100 μm, the minimum raised character 1 dot, the minimum reversed white character 1 dot, the solid image, the inspection negative film containing the procedure description, and using the 365nm illumination intensity of 17.5W/m²(Anderson&ランプ FR20T12-BL-9-BP manufactured by Vrieland corporation) was subjected to back exposure and surface exposure, the negative film was removed, developed with neutral water containing 4 wt% of sodium alkylnaphthalenesulfonate at 40 ℃ for 8 minutes, and dried at 60 ℃ for 20 minutes to obtain a printing plate.

The obtained printing plate has a relief depth of 0.8mm, and can obtain image reproducibility which cannot be realized by the conventional flexographic printing plate by printing with aqueous ink, namely, can reproduce dot 200 lines of 1-95%, minimum independent dot diameter of 100 mu m, minimum independent line width of 30 mu m, minimum reversed white line width of 100 mu m, minimum raised character 1 dot and minimum reversed white character 1 dot. In addition, the image reproducibility of 100 ten thousand printing experiments performed on the same printing plate did not change.

The viscosity of the stock solution thus prepared was 20P, and the resulting printing plate had a Shore A hardness of 63, a recovery elasticity of 60%, a water swelling rate after 1 hour of 1.5%, an ethanol swelling rate of 3.7%, a water swelling rate after 24 hours of 5.7%, an ethanol swelling rate of 5.2%, a light scattering rate at 365nm of 16.5%, and a tensile product of 280 (elongation 1.19X strength 235).

(example 4)

A butadiene latex (Nipol LX111NF nonvolatile content 55% manufactured by Nippon ゼォン Co., Ltd.) 62 parts by weight and an acrylonitrile-butadiene latex (Nipol SX1503 nonvolatile content 43% manufactured by Nippon ゼォン Co., Ltd.) 10 parts by weight were used as the component (A); 30 parts by weight of an oligobutadieneacrylate (ABU-2S, chemical Co., Ltd.) as component (B); 0.45 part by weight of a photopolymerization initiator as the component (C); 18 parts by weight of a hydrophilic polymer (PFT-3 nonvolatile matter, 25% Co., Ltd.) as the component (D); 0.3 part by weight of an anti-coagulation agent (ノィゲン SDX-60, manufactured by first Industrial pharmaceutical Co., Ltd.) as component (F); 4 parts by weight of lauryl methacrylate and 4 parts by weight of dimethylol tricyclodecane diacrylate as a crosslinking agent; 0.03 part by weight of hydroquinone monomethyl ether as a polymerization inhibitor; 0.04 parts by weight of a carboxylic acid copolymer as another additive was mixed with 15 parts by weight of toluene in a vessel, and the liquid state was observed immediately after the preparation and after 1 hour. Then kneaded at 105 with a pressure kneader, and then toluene and water were removed under reduced pressure. The obtained photosensitive resin composition was sandwiched between a film obtained by coating a polyester-based adhesive layer on a polyethylene terephthalate film having a thickness of 125 μm and a film obtained by coating an anti-blocking layer (polyvinyl alcohol) on the same polyethylene terephthalate film (the adhesive layer and the anti-blocking layer were brought into contact with the photosensitive resin composition), and the resultant was heated at 105 ℃ and 100kg/cm by a hot press²The pressure was applied for 1 minute, thereby obtaining a photosensitive resin original plate having a thickness of 1.7 mm. Stripping the obtained original plate, setting the dot 200 line 1% -95%, the minimum independent dot diameter 100 μm, the minimum raised character 1 dot, the minimum reversed white character 1 dot, the solid image, the inspection negative film containing the procedure description, and using the 365nm illumination intensity of 17.5W/m²(Anderson&ランプ FR20T12-BL-9-BP manufactured by Vrieland corporation) was subjected to back exposure and surface exposure, the negative film was removed, developed with neutral water containing 4 wt% of sodium alkylnaphthalenesulfonate at 40 ℃ for 8 minutes, and dried at 60 ℃ for 20 minutes to obtain a printing plate.

The obtained printing plate has a relief depth of 0.8mm, and can obtain image reproducibility which cannot be realized by the conventional flexographic printing plate by printing with aqueous ink, namely, can reproduce dot 200 lines of 1-95%, minimum independent dot diameter of 100 mu m, minimum independent line width of 30 mu m, minimum reversed white line width of 100 mu m, minimum raised character 1 dot and minimum reversed white character 1 dot. In addition, the image reproducibility of 100 ten thousand printing experiments performed on the same printing plate did not change.

The stock solution immediately after blending and 1 hour was uniform and did not change in state. The resulting printing plate had a shore a hardness of 63, a recovery elasticity of 60%, a water swelling rate after 1 hour of 1.5%, an ethanol swelling rate of 3.7%, a water swelling rate after 24 hours of 5.5%, an ethanol swelling rate of 5.0%, a light scattering rate at 365nm of 17.3%, and a tensile product of 280 (elongation 1.19 × strength 235).

(example 5)

A butadiene latex (Nipol LX111NF nonvolatile content 55% manufactured by Nippon ゼォン Co., Ltd.) 62 parts by weight and an acrylonitrile-butadiene latex (Nipol SX1503 nonvolatile content 42% manufactured by Nippon ゼォン Co., Ltd.) 10 parts by weight were used as the component (A); 20 parts by weight of an oligobutadieneacrylate (ABU-2S, chemical Co., Ltd.) as component (B); 0.45 part by weight of a photopolymerization initiator as the component (C); 18 parts by weight of a hydrophilic polymer (PFT-3 nonvolatile matter, 25% Co., Ltd.) as the component (D); 6 parts by weight of a conjugated diene oligomer having no crosslinking group (B2000, manufactured by Nippon petrochemicals Co., Ltd.) as the component (G); 6 parts by weight of lauryl methacrylate and 6 parts by weight of dimethylol tricyclodecane diacrylate as other crosslinking agents; 0.03 part by weight of hydroquinone monomethyl ether as a polymerization inhibitor was mixed with 6 parts by weight of toluene in a vessel, kneaded at 105 degrees by a pressure kneader, and then the toluene and water were removed under reduced pressure. A film obtained by coating a polyester-based adhesive layer on a polyethylene terephthalate film having a thickness of 125 μm and a film obtained by coating an anti-blocking layer (polyvinyl alcohol) on the same polyethylene terephthalate film were usedThe photosensitive resin composition of (1) was sandwiched (the adhesive layer and the anti-blocking layer were brought into contact with the photosensitive resin composition), and the resultant was heated at 105 ℃ and 100kg/cm by a hot press²The pressure was applied for 1 minute, thereby obtaining a photosensitive resin original plate having a thickness of 1.7 mm. Stripping the obtained original plate, setting the dot 200 line 1% -95%, the minimum independent dot diameter 100 μm, the minimum raised character 1 dot, the minimum reversed white character 1 dot, the solid image, the inspection negative film containing the procedure description, and using the 365nm illumination intensity of 17.5W/m²(Anderson&ランプ FR20T12-BL-9-BP manufactured by Vrieland corporation) was subjected to back exposure and surface exposure, the negative film was removed, developed with neutral water containing 4 wt% of sodium alkylnaphthalenesulfonate at 40 ℃ for 8 minutes, and dried at 60 ℃ for 20 minutes to obtain a printing plate.

The obtained printing plate has a relief depth of 0.8mm, and can obtain image reproducibility which cannot be realized by the conventional flexographic printing plate by printing with water-based ink and cosolvent ink, namely, the printing plate can reproduce 200-95% of halftone dots, the minimum independent dot diameter of 100 mu m, the minimum independent line width of 30 mu m, the minimum reversed white line width of 100 mu m, the minimum raised character 1 dot and the minimum reversed white character 1 dot. In addition, the image reproducibility of 100 ten thousand printing experiments performed on the same printing plate did not change. The resulting printing plate had a shore a hardness of 60, a recovery elasticity of 57.5%, a water swelling rate after 1 hour of 0.6%, an ethanol swelling rate of 2.3%, a cosolvent swelling rate of 3.8%, a water swelling rate after 24 hours of 3.5%, an ethanol swelling rate of 4.5%, a cosolvent swelling rate of 11.5%, a light scattering rate at 365nm of 28%, and a tensile product of 255.

The protective film and the antiblocking layer of the photosensitive resin original plate obtained were peeled off to expose the photosensitive resin composition layer, and the resultant was irradiated with light at 365nm at 17.5W/m²(Anderson&ランプ FR20T12-BL-9-BP manufactured by Vreeland Co., Ltd.) was subjected to back exposure and surface exposure, and the resulting plate had a compression elasticity of 1.62kgf, a compression elasticity after immersion in a cosolvent after 24 hours of 1.37kgf, a change rate before and after immersion of 15.4%, and a swelling rate of the cosolvent after 24 hours of 11.5%.

(example 6)

A butadiene latex (Nipol LX111NF nonvolatile content 55% manufactured by Nippon ゼォン Co., Ltd.) 62 parts by weight and an acrylonitrile-butadiene latex (Nipol SX1503 nonvolatile content 43% manufactured by Nippon ゼォン Co., Ltd.) 10 parts by weight were used as the component (A); 20 parts by weight of an oligobutadiene acrylate (manufactured by ABU-2S Kyoho chemical Co., Ltd.), 6 parts by weight of lauryl methacrylate (manufactured by ラィトェステル L Kyoho chemical Co., Ltd.), and 6 parts by weight of dimethylol tricyclodecane diacrylate as component (B); 0.45 part by weight of a photopolymerization initiator as the component (C); 18 parts by weight of a hydrophilic polymer (PFT-3 nonvolatile matter, 25% Co., Ltd.) as the component (D); 1 part by weight of a viscosity modifier (ァロン A-7050, manufactured by Toyo Synthesis Co., Ltd.) as component (E); 0.3 part by weight of an anti-coagulation agent (ノィゲン SDX-60, manufactured by first Industrial pharmaceutical Co., Ltd.) as component (F); 6 parts by weight of a conjugated diene oligomer having no crosslinking group (B2000, manufactured by Nippon petrochemicals Co., Ltd.) as the component (G); 0.03 part by weight of hydroquinone monomethyl ether as a polymerization inhibitor was mixed with 15 parts by weight of toluene in a vessel, and the viscosity of the stock solution was measured. Then kneaded at 105 with a pressure kneader, and then toluene and water were removed under reduced pressure. The obtained photosensitive resin composition was sandwiched between a film obtained by coating a polyester-based adhesive layer on a polyethylene terephthalate film having a thickness of 125 μm and a film obtained by coating an anti-blocking layer (polyvinyl alcohol) on the same polyethylene terephthalate film (the adhesive layer and the anti-blocking layer were brought into contact with the photosensitive resin composition), and the resultant was heated at 105 ℃ and 100kg/cm by a hot press²The pressure was applied for 1 minute, thereby obtaining a photosensitive resin original plate having a thickness of 1.7 mm. Stripping the obtained original plate, setting the dot 200 line 1% -95%, the minimum independent dot diameter 100 μm, the minimum raised character 1 dot, the minimum reversed white character 1 dot, the solid image, the inspection negative film containing the procedure description, and using the 365nm illumination intensity of 17.5W/m²(Anderson&ランプ FR20T12-BL-9-BP manufactured by Vrieland corporation) was subjected to back exposure and surface exposure, the negative film was removed, developed with neutral water containing 4 wt% of sodium alkylnaphthalenesulfonate at 40 ℃ for 8 minutes, and dried at 60 ℃ for 20 minutes to obtain a printing plate.

The obtained printing plate has a relief depth of 0.8mm, and can obtain image reproducibility which cannot be realized by the conventional flexographic printing plate by printing with aqueous ink, namely, can reproduce dot 200 lines of 1-95%, minimum independent dot diameter of 100 mu m, minimum independent line width of 30 mu m, minimum reversed white line width of 100 mu m, minimum raised character 1 dot and minimum reversed white character 1 dot. In addition, the image reproducibility of 100 ten thousand printing experiments performed on the same printing plate did not change.

The viscosity of the stock solution thus prepared was 20P, and the resulting printing plate had a Shore A hardness of 60, a recovered elasticity of 57.5%, a water swelling ratio after 1 hour of 1.5%, an ethanol swelling ratio of 3.7%, a water swelling ratio after 24 hours of 4.2%, an ethanol swelling ratio of 5.5%, a light scattering ratio at 365nm of 17.5%, and a tensile product of 260. The resulting plate had a compression elasticity of 1.62kgf, a compression elasticity after 24 hours of co-solvent immersion of 1.37kgf, a rate of change before and after immersion of 15.2%, and a co-solvent swelling rate after 24 hours of 11.4%.

Comparative example 1

A photosensitive resin composition was obtained in the same manner as in example 2 except that 62 parts by weight of solid polybutadiene (UBEPOL-BR130B, manufactured by Udo Kyoho Co., Ltd.) was blended in place of the hydrophobic polymer (β) butadiene latex as the component (A) in example 2. The negative film was removed by back exposure and top exposure, and developed with neutral water at 40 ℃ containing 4 wt% of sodium alkylnaphthalenesulfonate for 20 minutes, but only the relief depth was 0.4mm, and dot defects of highlight and filling of shadow were generated, and image reproducibility was significantly reduced.

Comparative example 2

In example 2, in addition to the hydrophobic polymer (α) as the (a) component: a flexographic printing plate was prepared in the same manner as in example 2 except that 10 parts by weight of acrylonitrile-butadiene latex (Nipol SX1503 non-volatile matter 43% manufactured by Japan ゼォン K.) was used, except that the hydrophobic polymer (. beta.) butadiene latex as the component (A) was used alone. The relief depth of the obtained printing plate was less than 0.8mm even after development for 20 minutes, and development failure was likely to occur.

Possibility of industrial application

The photosensitive resin composition of the present invention is useful in the industrial field, since it can be developed with an aqueous developer, has resistance to aqueous inks and cosolvent inks, and can be used for flexographic printing original plates having excellent image reproducibility.

Claims (14)

1. A photosensitive resin composition comprising: (A) at least two or more hydrophobic polymers obtained from an aqueous dispersion latex, (B) a photopolymerizable compound, (C) a photopolymerization initiator, wherein the two or more hydrophobic polymers are present in the form of fine particles.

2. The photosensitive resin composition according to claim 1, wherein the fine particles of component (A) have two or more peaks in the particle size distribution, and the particle size ratio of each peak is 2 times or more.

3. The photosensitive resin composition according to claim 1, further comprising (D) a hydrophilic polymer.

4. The photosensitive resin composition according to claim 3, wherein at least one of the hydrophobic polymers of the component (A) and the hydrophilic polymer of the component (D) have a common skeleton structure.

5. The photosensitive resin composition according to claim 1, further comprising (E) a viscosity modifier.

6. The photosensitive resin composition according to claim 5, wherein the component (E) is a carboxylic acid copolymer.

7. The photosensitive resin composition according to claim 1, further comprising (F) an anti-agglomeration agent.

8. The photosensitive resin composition according to claim 7, wherein the component (F) is a nonionic surfactant.

9. The photosensitive resin composition according to claim 1, further comprising (G) a conjugated diene oligomer having no crosslinking group.

10. The photosensitive resin composition according to claim 9, wherein the molecular weight of the component (G) is 500 to 10000.

11. The photosensitive resin composition according to any one of claims 1 to 10, wherein at least one of the components (B) is an alkyl methacrylate.

12. The photosensitive resin composition according to claim 11, wherein the alkyl methacrylate in the component (B) is linear having 8 to 18 carbon atoms.

13. A photosensitive resin composition layer obtained from the photosensitive resin composition according to claim 1, wherein the layer has a change rate of compression elasticity of 30% or less and a swelling rate of 16% or less before and after immersion in a cosolvent.

14. An original plate for photosensitive resin printing, which is characterized by being obtained by applying a photosensitive layer comprising the photosensitive resin composition according to any one of claims 1 to 13 onto a support.