JP2005148588A - Photosensitive resin composition and photosensitive resin printing original plate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive resin composition having proper image reproducing by being developed with a water-based developing solution and having resistance to water-based ink and cosolvent ink, and to provide a photosensitive resin printing original plate. <P>SOLUTION: The photosensitive resin composition includes (A) a hydrophobic polymer obtained from at least two or more kinds of water-dispersed latexes, (B) a hydrophilic polymer, (C) a photopolimerization compound, (D) a photopolymerization initiator, and (E) a conjugated diene oligomer which does not have crosslinkers. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photosensitive resin composition and a photosensitive resin printing original plate using the same, and particularly to a photosensitive resin composition for flexographic printing and a printing original plate that can be developed with an aqueous developer.

  Conventionally, a photosensitive resin composition in which an elastomer such as a chlorinated rubber, a styrene-butadiene block copolymer, or a polyurethane is used as a single resin component and an ethylenically unsaturated compound and a photopolymerization initiator are blended with the elastomer has characteristics of the elastomer. It is useful as a flexographic printing plate, and many proposals have been made.

Among these, particles having phase 1 mainly composed of a hydrophobic polymer and phase 2 mainly composed of a hydrophilic polymer are dispersed in a flexographic plate material which can be developed with an aqueous developer and has been provided with resistance to water-based ink. As a phase, a phase structure has been proposed in which a phase having a hydrophilic component and a hydrophobic component is a continuous phase (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 03-136052

  However, since solid rubber is used for the dispersed phase and the continuous phase in such a phase structure, fine particles aggregate in the phase structure formation stage, resulting in an increase in the particle size of the dispersed phase and non-uniformity. There was a tendency to become. Therefore, there has been a problem that the transmitted light is scattered and the image reproducibility of a minute relief is lowered.

Therefore, in order to reduce the particle size of the dispersed phase, it is proposed that a hydrophilic copolymer synthesized by emulsion polymerization as a dispersed phase or a polymer obtained from an aqueous dispersion latex is dispersed in a hydrophilic photopolymerizable monomer. (For example, see Patent Documents 2 and 3).
JP 2002-162731 A JP 2000-155417 A

  However, in these methods, although the dispersed phase is made into fine particles, solid rubber is used for the continuous phase that occupies the majority, so that the scattered light is scattered greatly and the image reproducibility of minute relief is sufficient. There was a problem that was not.

  Therefore, it has been found that a hydrophobic copolymer obtained from at least two kinds of water-dispersed latex corresponding to solid rubber is used for the dispersed phase and the continuous phase. As a result, the particle diameter of the dispersed phase becomes smaller and more uniform than in the prior art. Further, since the continuous phase is also finely divided, the transparency of the photosensitive resin composition layer is very high, scattering of transmitted light is remarkably reduced, and the image reproducibility of minute relief is improved. However, while printing using water-based ink achieves high image reproducibility, printing using cosolvent ink decreases image reproducibility. This is because two or more types of water-dispersed latex, which is the main component, have a butadiene skeleton in the molecular chain, so that it swells in cosolvents, especially acetate, blended in cosolvent inks. That is, the weight change rate is increased. For this reason, there has been a problem that fine relief image reproducibility is not sufficient, such as thin lines and halftone dots thickening in printing using cosolvent ink.

  In view of the above problems, the present invention provides a photosensitive resin composition and a photosensitive resin printing original plate that can be developed with an aqueous developer, have resistance to aqueous ink and cosolvent ink, and have good image reproducibility. It is to be an issue.

  In order to solve the above-mentioned problems, the present inventors have intensively studied, studied, and finally completed the present invention. That is, the present invention relates to (1) (A) a hydrophobic polymer obtained from at least two kinds of water-dispersed latex, (B) a hydrophilic polymer, (C) a photopolymerizable compound, and (D) a photopolymerization initiator. And (E) a photosensitive resin composition comprising a conjugated diene oligomer having no crosslinking group. (2) The photosensitive resin composition according to the above (1), wherein at least one hydrophobic polymer of the component (A) and the hydrophilic polymer of the component (B) each have a common skeleton structure. (3) The photosensitive resin composition according to the above (1), wherein the molecular weight of the component (E) is 500 to 10,000. (4) A photosensitive resin printing original plate comprising a support and a photosensitive layer comprising the photosensitive resin composition according to any one of (1) to (3). It is.

  By using the photosensitive resin composition of the present invention, it is possible to develop a flexographic printing original plate that can be developed with an aqueous developer, has resistance to water-based ink and cosolvent ink, and has good image reproducibility. It is great to contribute to

Hereinafter, an embodiment of the present invention will be described.
The water-dispersed latex used as the component (A) in the present invention is obtained by dispersing polymer particles in water as a dispersoid. Further, the hydrophobic polymer obtained from at least two kinds of water-dispersed latex is a hydrophobic polymer itself obtained by removing water from the water-dispersed latex, and it is necessary to use two or more kinds in the present invention. It is.

  Specifically, the component (A) is a latex selected from at least two or more of the following. 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 Examples thereof include water-dispersed latex polymers such as polymer latex, thiocol polymer latex and acrylate polymer latex, and polymers obtained by copolymerizing these polymers with other components such as acrylic acid and methacrylic acid. Among these, an aqueous dispersion latex polymer containing a butadiene skeleton or an isoprene skeleton in the molecular chain is 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 hydrophilic polymer as the component (B) of the present invention is -COOH, -COOM (M is a monovalent, divalent or trivalent metal ion or a substituted or unsubstituted ammonium ion), -OH, -NH _2. , —SO ₃ H, and those having a hydrophilic group such as a phosphate ester group are preferred. Specifically, a polymer of (meth) acrylic acid or a salt thereof, (meth) acrylic acid or a salt thereof and an alkyl (meth) Copolymer of acrylate, copolymer of (meth) acrylic acid or its salt and styrene, copolymer of (meth) acrylic acid or its salt and vinyl acetate, (meth) acrylic acid or its salt and acrylonitrile Copolymer, polyvinyl alcohol, carboxymethyl cellulose, polyacrylamide, hydroxyethyl cellulose, polyethylene oxide, polyester Ren'imin, polyurethane having -COOM group, polyureaurethane having -COOM group, include the polyamic acid and their salts or derivatives having a -COOM group. These may be used alone or in combination of two or more.

  The content of the component (B) is preferably 0.1 to 50 parts by weight, particularly 0.1 to 30 parts by weight with respect to 100 parts by weight of the component (A). If the amount is less than 0.1 parts by weight, development with an aqueous developer cannot be performed. If the amount exceeds 50 parts by weight, swelling with water increases and water-based ink resistance deteriorates.

  The photopolymerizable compound which is the component (C) of the present invention exists as a continuous layer. In the present invention, the photopolymerizable compound is preferably a photopolymerizable oligomer, and the photopolymerizable oligomer is a polymer in which an ethylenically unsaturated group is bonded to the terminal and / or side chain of a conjugated diene polymer. The number average molecular weight is 1000 or more and 10,000 or less. Specifically, it refers to a compound having the following structure in the molecular structure.

  The conjugated diene polymer constituting the conjugated diene ethylenic polymer is composed of a homopolymer of a conjugated diene unsaturated compound or a copolymer of a conjugated diene unsaturated compound and a monoethylenically unsaturated compound. As a homopolymer of such a conjugated diene unsaturated compound or a copolymer of a conjugated diene unsaturated compound and a monoethylenically unsaturated compound, a butadiene polymer, an isoprene polymer, a chloroprene polymer, a styrene-chloroprene copolymer, Acrylonitrile-butadiene copolymer, acrylonitrile-isoprene copolymer, methyl methacrylate-isoprene copolymer, acrylonitrile-isoprene copolymer, methyl methacrylate-isoprene copolymer, methyl methacrylate-chloroprene copolymer, acrylic acid Methyl-butadiene copolymer, methyl acrylate-isoprene copolymer, methyl acrylate-chloroprene copolymer, methyl acrylate-chloroprene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile copolymer Ropuren - styrene copolymer, and the like. Of these, a butadiene polymer, an isoprene polymer, and an acrylonitrile-butadiene copolymer are preferable from the viewpoint of rubber elasticity and photocurability, and a butadiene polymer and an isoprene polymer are particularly preferable.

  The method for introducing the terminal and / or side chain ethylenically unsaturated group of the conjugated diene polymer is not particularly limited. For example, (1) a hydroxyl group-terminated conjugated diene polymer obtained using hydrogen peroxide as a polymerization initiator. Monoethylenically unsaturated carboxylic acid such as (meth) acrylic acid or the like is ester-bonded to the terminal hydroxyl group by dehydration reaction, or monoethylenically unsaturated carboxylic acid such as methyl (meth) acrylate or ethyl (meth) acrylate (2) Conjugated diene heavy compounds obtained by copolymerizing an ethylenically unsaturated compound containing an unsaturated carboxylic acid (ester) at least partly with a conjugated diene compound. Examples include a method of reacting ethylenically unsaturated alcohol such as allyl alcohol and vinyl alcohol with the coalescence. .

  The amount of the ethylenically unsaturated group in the conjugated diene-based ethylenic polymer is preferably 0.005 to 2.0 meq / g, particularly preferably 0.01 to 2.0 meq in the polymer. When the amount is more than 2.0 m equivalent / g, the hardness becomes too high and it becomes difficult to obtain sufficient elasticity. When the amount is less than 0.005 m equivalent / g, the reactivity decreases and the image reproducibility tends to decrease.

  The content of the component (C) is preferably 1 to 200 parts by weight with respect to 100 parts by weight of the component (A). If the amount is 1 part by weight or less, the raw plate becomes hard and development with an aqueous developer cannot be performed. If the amount is 200 parts by weight or more, the raw plate becomes too soft and handling properties are deteriorated.

  In the present invention, a hydrophobic monomer can be added as necessary within a range not inhibiting the effects of the present invention. The hydrophobic monomer is a monomer that generally does not have a functional group having a strong polarity in the monomer, and is a monomer having low solubility in water or ethanol.

  Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl Alkyl (meth) acrylates such as (meth) acrylate, cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate, halogenated alkyl (meth) acrylates such as chloroethyl (meth) acrylate and chloropropyl (meth) acrylate, methoxyethyl Alkoxyalkyl (meth) acrylates such as (meth) acrylate, ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, Such as phenoxyalkyl (meth) acrylates such as sulfonyl phenoxyethyl (meth) acrylate.

  When these hydrophobic monomers are added, the content is preferably 200 parts by weight or less with respect to 100 parts by weight of component (A). By making it 200 parts by weight or less, water developability is excellent and a good relief can be obtained.

  Moreover, the photosensitive resin composition of this invention adds a photoinitiator as (D) component. Any photopolymerization initiator can be used as long as it can polymerize a polymerizable carbon-carbon unsaturated group by light. Especially, what has the function to produce | generate a radical by self-decomposition or hydrogen abstraction by light absorption is used preferably. For example, benzoin alkyl ethers, benzophenones, anthraquinones, benzyls, acetophenones, diacetyls and the like. As a compounding quantity of a photoinitiator, the range of 0.1-50 weight part is preferable with respect to 100 weight part of (A) component. By setting it to 0.1 parts by weight or more, the image reproduction is good without reducing the starting efficiency. The amount of 50 parts by weight or less is preferable because the sensitivity is not too high and the exposure time can be easily controlled.

  In the present invention, the conjugated diene oligomer having no crosslinking group as the component (E) lowers the crosslinking density of the photosensitive resin composition layer, and absorbs cosolvent absorption and oligomer component extraction that occurs during printing using the cosolvent ink. It is for adjusting and reducing the apparent weight change rate. As the conjugated diene oligomer having no crosslinking group, a conjugated diene oligomer having no crosslinking group having at least a 1,2-butadiene skeleton is preferable. The molecular weight of the conjugated diene oligomer having a 1,2-butadiene skeleton and not having a crosslinking group is preferably in the range of 500 to 10,000, more preferably 1000 to 5000, and particularly preferably 1000 to 4000. When the molecular weight is less than 500, not only the handling of the resin plate is deteriorated, but also the strength of the plate is impaired due to extraction of a large amount of oligomer components into the cosolvent contained in the cosolvent ink, or due to repeated printing. This is not preferable because the hardness of the plate changes and the finish of the printed matter changes. Moreover, since the reduction | decrease of the weight change rate after the cosolvent immersion which is anticipated that molecular weight exceeds 10,000 is not acquired, and compatibility with the photosensitive resin component is also impaired, it is unpreferable.

  Such conjugated diene oligomers having a 1,2-butadiene skeleton include polybutadiene oligomers having no terminal functional group, polystyrene-butadiene oligomers, polyacrylonitrile-butadiene oligomers, polyisoprene oligomers, polychloroprene oligomers, terminal allyl groups. -Containing polybutadiene oligomer, terminal allyl group-containing polystyrene-butadiene oligomer, terminal allyl group-containing polyacrylonitrile-butadiene oligomer, terminal allyl group-containing polyisoprene oligomer, terminal allyl group-containing polychloroprene oligomer, terminal hydroxyl group-containing polybutadiene oligomer, terminal hydroxyl group-containing polystyrene- Butadiene oligomers, terminal hydroxyl group-containing polyacrylonitrile-butadiene oligomers, terminal hydroxyl group-containing polyisopres Oligomer, terminal hydroxyl group-containing polychloroprene oligomer, terminal carboxyl group-containing polybutadiene oligomer, terminal carboxyl group-containing polystyrene-butadiene oligomer, terminal carboxyl group-containing polyacrylonitrile-butadiene oligomer, terminal carboxyl group-containing polyisoprene oligomer, terminal carboxyl group-containing polychloroprene oligomer , Terminal amino group-containing polybutadiene oligomer, terminal amino group-containing polystyrene-butadiene oligomer, terminal amino group-containing polyacrylonitrile-butadiene oligomer, terminal amino group-containing polyisoprene oligomer, terminal amino group-containing polychloroprene oligomer, and the like.

  The content of the component (E) is 1 to 200 parts by weight, preferably 3 to 100 parts by weight, and more preferably 5 to 30 parts by weight with respect to 100 parts by weight of the component (A). If the amount is less than 1 part by weight, the raw plate becomes hard and cannot be developed with an aqueous developer. If the amount exceeds 200 parts by weight, the raw plate becomes too soft and the handling property is deteriorated.

  A plasticizer can be further added to the photosensitive resin composition of the present invention. The plasticizer is not particularly limited as long as it generally has a property of softening the plate material, but those having good compatibility with the component (A) and the component (B) are preferable. More preferred are polyene compounds which are liquid at room temperature and compounds having an ester bond. Examples of the polyene compound which is liquid at room temperature include liquid polybutadiene, polyisoprene, and maleated products and epoxidized products having their end groups or side chains modified. Examples of the compound having an ester bond include phthalic acid ester, phosphoric acid ester, sebacic acid ester, adipic acid ester, and polyester having a molecular weight of 1000 to 3000.

  When these plasticizer components are added, 0 to 100 parts by weight is preferable with respect to 100 parts by weight of component (A) from the viewpoint of obtaining sufficient strength as a solid plate before photocrosslinking.

  In order to increase the thermal stability of the photosensitive resin composition of the present invention, a conventionally known polymerization inhibitor may be added. Preferable polymerization inhibitors include phenols, hydroquinones, catechols and the like. These compounding amounts are generally used in the range of 0.001 to 5% by weight with respect to the total photosensitive resin composition.

  Moreover, dye, a pigment, a viscosity modifier, an antifoamer, a ultraviolet absorber, a fragrance | flavor, etc. can be added as another component.

  The photosensitive resin composition of the present invention preferably has a form in which the hydrophobic polymer obtained from the water-dispersed latex as the component (A) is dispersed in the photopolymerizable compound as the component (C). . By having such a form, it is considered that the polymers obtained from the water-dispersed latex of component (A) can be present in the composition without fusing.

  In order that the photosensitive resin composition of this invention may maintain the precision as a printing plate, you may provide support bodies, such as polyester, on the opposite side of a relief. The photosensitive resin composition of the present invention may become sticky depending on the composition thereof, so that the contact with the transparent image carrier (negative film) superimposed thereon can be improved and the image carrier can be reused. Therefore, a flexible film layer that can be developed in an aqueous system may be provided on the surface. The photosensitive resin composition of this invention can be manufactured by mixing each component. As the means, after mixing the resin composition using an extruder, a kneader or the like, it is possible to form a layer having a desired thickness by hot press molding, calendering or extrusion molding. The support and the flexible film layer can be adhered to the photosensitive layer by roll lamination after sheet molding. A highly sensitive photosensitive layer can also be obtained by heating and pressing after lamination. Examples of the active light source used for photocuring the photosensitive resin composition of the present invention include a low-pressure mercury lamp, a high-pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, a xenon lamp, a zirconium lamp, and sunlight. After the photosensitive resin composition of the present invention is irradiated with light through a transparent image carrier to form an image, a non-irradiated portion is removed (developed) using an aqueous developer to obtain a relief (printing plate).

  The aqueous developer referred to in the present invention is prepared by blending water with a nonionic or anionic surfactant, and if necessary, a pH adjusting agent, a cleaning accelerator and the like. Specific examples of nonionic surfactants include polyoxyalkylene alkyl or alkenyl ether, polyoxyalkylene alkyl or alkenyl phenyl ether, polyoxyalkylene alkyl or alkenyl amine, polyoxyalkylene alkyl or alkenyl amide, ethylene oxide / propylene oxide There are block appendages. Specific examples of the anionic surfactant include linear alkyl benzene sulfonate having alkyl having an average carbon number of 8 to 16, α-olefin sulfonate having an average carbon number of 10 to 20, alkyl group or alkenyl group. A dialkyl sulfosuccinate having 4 to 10 carbon atoms, a sulfonate of a fatty acid lower alkyl ester, an alkyl sulfate having an average carbon number of 10 to 20, a linear or branched alkyl or alkenyl group having an average carbon number of 10 to 20 And alkyl ether sulfates having an average of 0.5 to 8 moles of ethylene oxide, saturated or unsaturated fatty acid salts having an average carbon number of 10 to 22 and the like.

  Examples of the PH adjuster include sodium borate, sodium carbonate, sodium silicate, sodium metasilicate, sodium succinate, sodium acetate, and the like. Sodium silicate is preferred because it is easily dissolved in water. Further, although there is a cleaning aid, the cleaning ability is enhanced by using it together with the surfactant and the pH adjusting agent. Specific examples include amines such as monoethanolamine, diethanolamine and triethanolamine, ammonium salts such as tetramethylammonium hydroxide, and paraffinic hydrocarbons. These are used by being added and mixed with water in an appropriate amount in the range of 0.1 to 50% by weight, preferably 1 to 10% by weight. After development, the plate is generally dried in an oven at about 60 ° C. for 15 to 120 minutes.

  Depending on the composition of the photosensitive resin composition of the present invention, stickiness may remain on the plate surface even after drying is finished. In that case, stickiness can be removed by a known surface treatment method. As the surface treatment method, an exposure treatment with an actinic ray having a wavelength of 300 nm or less is desirable.

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

Hereinafter, the present invention will be specifically described with reference to examples.
In addition, the characteristic value in an Example is a value obtained by the following measuring methods.
(1) Hardness: a value measured at 20 ° C. by a spring-type hardness test (A type) method according to JIS-K6301.
(2) Rebound resilience: A steel ball with a diameter of 10m / m (weight 4.16g) dropped from a height of 20cm, and the bounce height (a) was read and displayed as (a / 20) x 100%. .
(3) Swelling ratio: The weight increase rate (%) is measured after the printing plate is immersed in water, ethanol and cosolvent (isopropyl alcohol / n-propyl acetate = 8/2) at 20 ° C. for 1 hour or 24 hours. did.
(4) Light scattering rate: The scattering rate at λ = 365 nm of the photosensitive resin composition was measured using a spectrophotometer (U-3210, manufactured by Hitachi, Ltd., with a 150φ integrating sphere accessory device).

Example 1
(A) component butadiene latex (Nipol LX111NF nonvolatile content 55% manufactured by Nippon Zeon Co., Ltd.) 22 parts by weight, acrylonitrile-butadiene latex (Nipol SX1503 nonvolatile content 42% manufactured by Nippon Zeon Co., Ltd.) 5 parts by weight, (B ) Component hydrophilic polymer (PFT-3 nonvolatile content 25% manufactured by Kyoeisha Chemical Co., Ltd.) 6 parts by weight, component (C) oligobutadiene acrylate (ABU-2S manufactured by Kyoeisha Chemical Co., Ltd.) 6 parts by weight , 0.45 parts by weight of photopolymerization initiator as component (D), 3 parts by weight of conjugated diene oligomer (B2000 manufactured by Nippon Petrochemical Co., Ltd.) having no crosslinking group as component (E), lauryl methacrylate as a crosslinking agent 2 parts by weight, 1.8 parts by weight of dimethylol tricyclodecane diacrylate, 0.03 part by weight of hydroquinone monomethyl ether as a polymerization inhibitor Were mixed in a vessel with 6 parts by weight, then kneaded at 105 ° C. using a pressure kneader, after which toluene and water were removed under reduced pressure. The obtained photosensitive resin composition is sandwiched between a film in which a polyester adhesive layer is coated on a polyethylene terephthalate film having a thickness of 125 μm and a film in which an anti-tacking layer (polyvinyl alcohol) is coated on the same polyethylene terephthalate film (adhesive layer). The pressure-sensitive adhesive layer is brought into contact with the photosensitive resin composition), and a photosensitive resin original plate having a thickness of 1.7 mm is prepared by applying pressure with a heat press at 105 ° C. and a pressure of 100 kg / cm ² for 1 minute. did. The obtained original plate was peeled off and applied to an inspection negative including a halftone dot line of 1% to 95%, a minimum independent point diameter of 100 μm, a minimum convex character of 1 point, a minimum extracted character of 1 point, a solid image and a step guide Back exposure and front exposure were performed using an illuminance of 17.5 W / m ² (Anderson & Vreland lamp FR20T12-BL-9-BP), the negative film was removed, and 40 ° C. containing 4% by weight of sodium alkylnaphthalenesulfonate. Development was carried out with neutral water for 8 minutes and dried at 60 ° C. for 20 minutes.

  The obtained printing plate has a relief depth of 0.8 mm, and is printed with water-based ink and cosolvent ink, with a halftone dot line of 1% to 95%, a minimum independent point diameter of 100 μm, a minimum independent line width of 30 μm, and a minimum. Image reproducibility that could not be realized by a conventional flexographic printing plate that reproduces a blank line width of 100 μm, a minimum convex character of 1 point, and a minimum extracted character of 1 point was obtained. In addition, a printing test of 1 million sheets was performed using the printing plate, but no change was observed in image reproducibility.

  The obtained printing plate has a Shore A hardness of 60, a rebound resilience of 57%, a water swelling ratio of 0.6% after 1 hour, an ethanol swelling ratio of 2.3%, a cosolvent swelling ratio of 14.1%, After 24 hours, the water swelling rate was 2.1%, the ethanol swelling rate was 4.5%, the cosolvent swelling rate was 15.6%, and the light scattering rate at 365 nm was 28%.

Example 2
In Example 1, 23 parts by weight of component (A) butadiene latex (Nipol LX111NF non-volatile content 55% made by Nippon Zeon Co., Ltd.), acrylonitrile-butadiene latex (Nipol SX1503 non-volatile content 42% made by Nippon Zeon Co., Ltd.) 4 Part by weight, hydrophilic polymer (B) component (PFT-3 nonvolatile content 25%, manufactured by Kyoeisha Chemical Co., Ltd.) 3.6 parts by weight, component (C) oligobutadiene acrylate (ABU-2S Kyoeisha Chemical ( Co., Ltd.) 5 parts by weight, (D) component photopolymerization initiator 0.45 part by weight, (E) component conjugated diene oligomer having no crosslinking group (B2000 made by Nippon Petrochemical Co., Ltd.) 5 parts by weight A flexographic printing plate was prepared in the same manner as in Example 1 except that 3 parts by weight of lauryl methacrylate and 2 parts by weight of dimethylol tricyclodecane diacrylate were used as a crosslinking agent. It was. The obtained printing plate showed the same image reproducibility and printing durability as Example 1.

  The obtained printing plate has a Shore A hardness of 62, a rebound resilience of 52%, a water swelling ratio of 0.9% after 1 hour, an ethanol swelling ratio of 2.6%, a cosolvent swelling ratio of 14.9%, After 24 hours, the water swelling rate was 3.3%, the ethanol swelling rate was 5.8%, the cosolvent swelling rate was 13.8%, and the light scattering rate at 365 nm was 23%.

Comparative Example 1
In Example 1, except for 3 parts by weight of the conjugated diene oligomer (B2000 made by Nippon Petrochemical Co., Ltd.) which is a component (E) which is a component (E), a butadiene latex (Nipol LX111NF nonvolatile content 55%) Nippon Zeon Co., Ltd.) 22 parts by weight, acrylonitrile-butadiene latex (Nipol SX1503 non-volatile content 43% Nippon Zeon Co., Ltd.) 5 parts by weight, component (B) hydrophilic polymer (PFT-3 non-volatile content 25) % Kyoeisha Chemical Co., Ltd.) 5 parts by weight, (C) Component Eugobutadiene Acrylate (ABU-2S Kyoeisha Chemical Co., Ltd.) 10 parts by weight, (D) Photopolymerization initiator 0.45 Flexographic printing in the same manner as in Example 1 except that 3 parts by weight of lauryl methacrylate and 0.9 part by weight of dimethylol tricyclodecane diacrylate were used as a crosslinking agent. It was produced. The obtained printing plate showed the same image reproducibility and printing durability as in Example 1 when printed with water-based ink, but the image reproducibility was slightly increased when printing with cosolvent ink. A decrease was seen.

  The obtained printing plate has a Shore A hardness of 58, a rebound resilience of 65%, a water swelling ratio of 1.5% after 1 hour, an ethanol swelling ratio of 3.7%, a cosolvent swelling ratio of 14.8%, After 24 hours, the water swelling rate was 3.5%, the ethanol swelling rate was 5.8%, the cosolvent swelling rate was 17.9%, and the light scattering rate at 365 nm was 17.3%.

Comparative Example 2
A flexographic printing plate was prepared in the same manner as in Example 1, except that 5 parts by weight of acrylonitrile-butadiene latex (Nipol SX1503 non-volatile content: 43% manufactured by Nippon Zeon Co., Ltd.) as component (A) was removed. did. The obtained printing plate did not reach a relief depth of 0.8 mm even when developed for 20 minutes, and was poorly developed.

Comparative Example 3
A flexographic printing plate was obtained in the same manner as in Example 1 except that 6 parts by weight of the hydrophilic polymer (PFT-3 nonvolatile content 25%, manufactured by Kyoeisha Chemical Co., Ltd.) as component (B) was removed. Produced. The obtained printing plate did not reach a relief depth of 0.8 mm even when developed for 20 minutes, and was poorly developed.

Comparative Example 4
In Example 1, except for the oligobutadiene acrylate (ABU-2S manufactured by Kyoeisha Chemical Co., Ltd.) which is the component (C), a conjugated diene oligomer (B2000 Nippon Petrochemical Co., Ltd.) having no crosslinking group as the component (E) A flexographic printing plate was prepared in the same manner as in Example 1 except that 9 parts by weight were used. The obtained printing plate did not reach a relief depth of 0.8 mm even when developed for 20 minutes, and was poorly developed.

  As described above, the photosensitive resin composition of the present invention having such a configuration can be developed with an aqueous developer, has resistance to water-based inks and cosolvent inks, and can be used for an original plate for flexographic printing with good image reproducibility. .

Claims (4)

  (A) Hydrophobic polymer obtained from at least two kinds of water-dispersed latex, (B) hydrophilic polymer, (C) photopolymerizable compound, (D) photopolymerization initiator and (E) having a crosslinking group A photosensitive resin composition having no conjugated diene oligomer.   The photosensitive resin composition according to claim 1, wherein at least one hydrophobic polymer of component (A) and the hydrophilic polymer of component (B) each have a common skeleton structure.   The photosensitive resin composition according to claim 1, wherein the component (E) has a molecular weight of 500 to 10,000.   A photosensitive resin printing original plate, comprising a photosensitive layer made of the photosensitive resin composition according to any one of claims 1 to 3 on a support.