JP2009271277A - Photosensitive resin composition and printing plate material using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive resin composition which excels in water developability and image reproducibility and does not cause warpage to a printing plate precursor or a printing plate, in a state of the raw plate and at any stage, after plate making/plate setting, and to provide a printing plate material that uses the same. <P>SOLUTION: The photosensitive resin composition contains a water-soluble or water-swellable polymer (A), an ethylenically unsaturated compound (B), and a photopolymerization initiator (C), wherein the water-soluble or water-swellable polymer (A) contains a partially saponified polyvinyl acetate (a), and the ethylenically unsaturated compound (B) contains urethane (meth)acrylate (b). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photosensitive resin composition, a photosensitive printing plate having a photosensitive resin layer comprising the same, and a printing plate using the same.

  The use of a photosensitive resin composition as a printing plate material is generally performed, and has become mainstream in each field of letterpress, planographic and intaglio printing.

  The photosensitive resin composition utilized for such a printing plate material generally comprises a polymer, an ethylenically unsaturated compound, and a photopolymerization initiator, and uses a modified PVA as a polymer (for example, Patent Document 1). ), Various photosensitive resin compositions such as a photosensitive resin composition using urethane acrylate as an ethylenically unsaturated compound (for example, Patent Document 2) have been proposed.

  At present, most of the used printing plates can be developed with water, and such photosensitive resin compositions have a structure such as a raw material polymer or an ethylenically unsaturated compound in order to impart water developability. Has a hydrophilic group (hydroxyl group, amide group, polyoxyalkylene group, etc.), has high water absorption, and has a problem that the printing plate is warped due to a change in the humidity dimension of the photosensitive layer after the printing plate is prepared. . In general, a photosensitive resin printing plate has a structure in which a photosensitive resin layer and a support are laminated. When the photosensitive resin layer is dried and contracted during plate placement, the photosensitive resin layer is supported on the inside. Often warps so that is on the outside. On the other hand, when the printing plate is set on the plate cylinder of the printing press, it is necessary to warp the photosensitive resin layer to the outside, and at that time, a trouble that the printing plate is cracked by an external force tends to occur. Further, although the printing plate is fixed to the plate cylinder with a double-sided tape or the like, problems such as the printing plate floating from the plate cylinder due to warping are likely to occur. From such a background, it has been proposed to use a reaction product of a partially saponified polyvinyl acetate and an aldehyde as a polymer component in the photosensitive resin composition (Patent Document 3).

Printing plate materials using a photosensitive resin composition are conventionally dissolved in a portion that dissolves in the developer in the photosensitive layer by adhering a negative or positive original film to the photosensitive layer and irradiating actinic rays through the original film. In general, a relief image is formed by forming a portion not to be used and used as a printing plate. With the advancement of computers in recent years, a so-called CTP (computer to plate) method has been proposed in which information processed on a computer is directly output onto a printing plate material, and a relief printing plate can be obtained without the need to create an original film. (Patent Document 4). When a conventional original image film is used, the original image film is vacuum-adhered to the printing plate, and as a result, a part of the printing plate is fixed without floating from the exposure table. However, in the mask type CTP plate, in order to improve image reproducibility, it is common not to perform vacuum adhesion at the time of exposure. If there is a warp on the printing original plate before exposure, ultraviolet rays are incident vertically on the entire printing original plate. Therefore, the image reproducibility may be significantly impaired. Therefore, it is necessary to fix the printing original plate on the exposure table.
JP-A-8-254826 (Claims) JP 63-278053 (Claims) JP-A-7-319160 (Claims) JP-A-2004-163925 (Claims)

  The present invention is intended to solve the above-mentioned problems, is excellent in water developability and image reproducibility, and does not warp the printing original plate or the printing plate at any stage after raw plate, plate making and plate setting. It is an object to provide a photosensitive printing composition having a photosensitive resin composition, a photosensitive resin layer comprising the same, and a printing plate using the same.

  In order to solve the above problems, the present invention mainly has the following configuration. That is, “a photosensitive resin composition containing a water-soluble or water-swellable polymer (A), an ethylenically unsaturated compound (B), a photopolymerization initiator (C), and comprising a water-soluble or water-swellable polymer (A ) Contains partially saponified polyvinyl acetate (a), and the ethylenically unsaturated compound (B) contains urethane (meth) acrylate (b).

  Further, “a photosensitive printing original plate having at least a support (D) and a photosensitive resin layer (E), wherein the photosensitive resin layer (E) is made of the photosensitive resin composition, and warps after placing the plate. And a photosensitive printing original plate having at least a support (D) and a photosensitive resin layer (E), wherein the photosensitive resin layer has a central angle of 180 ° or less. (E) is a photosensitive printing original plate characterized in that it comprises the above-mentioned photosensitive resin composition, and the center angle of warpage of the raw plate is ± 45 ° or less. ”

  According to the present invention, a photosensitive resin composition that is excellent in water developability and image reproducibility and that does not warp a printing original plate or a printing plate at any stage after printing, plate making and plate setting, and a photosensitive resin layer comprising the same And a printing plate using the same can be provided.

  The photosensitive resin composition in the present invention contains a water-soluble or water-swellable polymer (A).

  The water-soluble or water-swellable polymer in the present invention is a polymer that dissolves or disperses in water when immersed in water at 25 ° C. for 24 hours. Specific examples of water-soluble or water-swellable polymers include partially saponified polyvinyl acetate, polyvinyl alcohol, polyamide resins having a hydrophilic group such as polyoxyalkylene segment or alicyclic diamine segment in the polymer main chain, and these resins Examples thereof include modified resins, and other known water-soluble or water-swellable polymers can also be used.

  The water-soluble or water-swellable polymer (A) of the present invention needs to contain a partially saponified polyvinyl acetate (a) because it is excellent in water developability and image reproducibility and has little plate surface adhesion. The degree of saponification of the partially saponified polyvinyl acetate (a) is preferably 60 to 85 mol%, more preferably 65 to 75 mol%. If it is the range of 60-85 mol%, compatibility with an ethylenically unsaturated compound (B) is fully ensured. If the saponification degree is 60 mol% or more, the water developability is good. If the saponification degree is 85 mol% or less, the water absorption of the polymer is suppressed, and the crystallinity is reduced, so that the photosensitive resin is flexible. In addition, the effect of reducing warpage when a printing plate is used can be obtained.

  As a method for measuring the degree of saponification of partially saponified polyvinyl acetate (a), according to JIS K6726 (1994) 3.5 degree of saponification, the residual acetic acid groups (mol%) in partially saponified polyacetic acid were quantified with sodium hydroxide, The degree of saponification (mol%) can be measured by subtracting from 100.

  The degree of polymerization of the partially saponified polyvinyl acetate (a) is preferably a number average degree of polymerization of 300 to 1000, more preferably 300 to 800. If the degree of polymerization is 300 or more, toughness can be imparted to the photosensitive resin, and if it is 1000 or less, good water developability is maintained.

  As a method for measuring the degree of polymerization of partially saponified polyvinyl acetate (a), according to JIS K6726 (1994) 3.7 average degree of polymerization, partially saponified polyvinyl acetate was completely saponified with sodium hydroxide, and then water was measured using a viscometer. And the average degree of polymerization can be calculated from the relative viscosity.

  The partially saponified polyvinyl acetate (a) preferably has a reactive group capable of crosslinking with the ethylenically unsaturated compound (B). As the crosslinkable reactive group, a group obtained by introducing a polymerizable unsaturated bond into a part of partially saponified polyvinyl acetate is preferably used. For example, modified partially saponified polyvinyl obtained by reacting partially saponified polyvinyl acetate and dicarboxylic anhydride to add a carboxyl group to the side chain. Examples of the acid anhydride include maleic anhydride, trimellitic anhydride, succinic anhydride, phthalic anhydride, pyromellitic anhydride, glutaric anhydride, hydrogenated phthalic anhydride, naphthalene dicarboxylic acid anhydride, and the like. The content of the acid anhydride residue is preferably in the range of 0.1 to 10 mol% with respect to the sum of the vinyl acetate unit and the vinyl alcohol unit before the reaction. If it is 0.1 mol% or more, image reproducibility and printing durability are good, and if it is 10 mol% or less, good water developability is maintained.

  As a method of reacting partially saponified polyvinyl acetate and dicarboxylic anhydride and introducing a carboxyl group into the polymer side chain, partially saponified polyvinyl acetate is swollen in acetone, N, N-dimethylformamide (DMF) or the like, Examples thereof include a method of reacting with an acid anhydride and then drying to obtain a modified partially saponified polyvinyl acetate.

  By reacting a carboxy group present in the side chain of the modified partially saponified polyvinyl acetate thus obtained with an unsaturated epoxy compound, a polymerizable unsaturated bond is bonded to the partially saponified polyvinyl acetate (a) of the present invention. Can be introduced. As a result, it has the effect of strengthening the crosslinked structure of the photosensitive resin composition by photopolymerization.

  An unsaturated epoxy compound is a compound having at least one epoxy group and at least one ethylenically unsaturated group in the molecule. As the ethylenically unsaturated group, an acryloyl group and a methacryloyl group are particularly preferable. Specific examples of the unsaturated epoxy compound include glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexyl acrylate, 3,4-epoxycyclohexyl methacrylate, and the like. These unsaturated epoxy compounds can be used alone or in combination of two or more.

  Further, the water-soluble or water-swellable polymer and other polymers can be mixed and used. Polymers to be mixed include polyamide resin, polybutadiene, acrylonitrile rubber, butadiene-acrylonitrile copolymer, butadiene-styrene copolymer, isoprene-styrene copolymer, cellulose derivative, polyester resin, silicone rubber, acrylic resin, polyurethane resin, epoxy resin, polystyrene, polypropylene , Polyethylene, chlorinated polyethylene, polyvinyl chloride, partially saponified polyvinyl acetate, copolymers thereof, and the like, which are usually used in photosensitive resin compositions.

  In the photosensitive resin composition, the content of the water-soluble or water-swellable polymer (A) in the present invention is preferably 30 to 70 wt%, more preferably 40 to 60 wt%. When the content is 30 wt% or more, toughness is imparted to the printing plate and printing durability is improved, and when it is 70 wt% or less, developability and image reproducibility are improved.

  The ethylenically unsaturated compound (B) of the present invention is a compound that can be cross-linked by radical polymerization, and can contain a known ethylenically unsaturated compound. Examples of such ethylenically unsaturated compounds include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-chloro-2-hydroxypropyl (meth) acrylate. , Β-hydroxy-β ′-(meth) acryloyloxyethyl phthalate and other hydroxyl group-containing (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isoamyl Alkyl (meth) acrylates such as (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cycloalkyl such as cyclohexyl (meth) acrylate (meta ) Alkoxyalkyl (meth) acrylates such as acrylate, chloroethyl (meth) acrylate, chloropropyl (meth) acrylate, alkoxyalkyl such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate ( Phenoxyalkyl (meth) acrylates such as (meth) acrylate, phenoxyethyl acrylate, nonylphenoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, etc. Alkoxyalkylene glycol (meth) acrylate, 2,2-dimethylaminoethyl (meth) acrylate, 2,2-die Aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) ) Compounds having only one ethylenically unsaturated bond, such as acrylate, di (meth) acrylates of polyethylene glycol such as diethylene glycol di (meth) acrylate, polypropylene glycol di (meta) such as dipropylene glycol di (meth) acrylate ) Acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol tri (meth) acrylate, Unsaturation such as polyvalent (meth) acrylate and glycidyl (meth) acrylate obtained by addition reaction of ethylenically unsaturated bonds such as unsaturated carboxylic acid and unsaturated alcohol with active hydrogen to lenglycol diglycidyl ether Multivalent (meth) acrylamides such as polyvalent (meth) acrylates and methylenebis (meth) acrylamides obtained by addition reaction of epoxy compounds and compounds having active hydrogen such as carboxylic acids and amines, and polyvalent vinyls such as divinylbenzene And compounds having two or more ethylenically unsaturated bonds, such as compounds.

  The content of the ethylenically unsaturated compound (B) in the present invention is preferably 20 to 60 wt%, more preferably 30 to 50 wt% in the photosensitive resin composition. When the content is 20 wt% or more, the photo-curing of the photosensitive resin can sufficiently proceed to form a relief of the printing plate, and when the content is 60 wt% or less, printing without impairing the flexibility of the photosensitive resin. The printing durability of the plate is maintained.

  The ethylenically unsaturated compound (B) of the present invention preferably contains urethane (meth) acrylate (b) as an essential component from the viewpoints of flexibility and image reproducibility.

  The urethane (meth) acrylate (b) of the present invention is a compound having at least one urethane structure, polyoxyalkylene structure and ethylenically unsaturated group in the molecule.

  The urethane (meth) acrylate (b) of the present invention preferably has a urethane structure in the molecule from the viewpoints of flexibility and elasticity.

  The urethane (meth) acrylate (b) of the present invention preferably has a polyoxyalkylene structure in the molecule from the viewpoints of flexibility, water developability and water retention. As the polyoxyalkylene structure of the present invention, a polyoxyethylene structure or a polyoxypropylene structure can be preferably used from the viewpoint of water developability and water retention.

  The number of ethylenically unsaturated groups in the urethane (meth) acrylate (b) of the present invention is preferably 1 to 4, more preferably 1 to 3. When the number is 1 or more, the image reproducibility is good, and when the number is 4 or less, good compatibility can be maintained.

  As a method for producing the urethane (meth) acrylate (b) of the present invention, for example, after reacting a polyol compound having two or more hydroxyl groups with a polyisocyanate compound to form a urethane bond, carboxylic acid and ethylene are added to the hydroxyl group of the polyol compound, for example. It can be produced by reacting a compound having a polymerizable unsaturated group.

  In addition to the polyol compound having two or more hydroxyl groups, if necessary, other active hydrogen-containing compounds (amines, amides, carboxylic acids, etc.) are reacted with polyisocyanate to produce the urethane (meth) acrylate (b ) Can also be used.

  A publicly known method can be used as a manufacturing method of urethane (meth) acrylate (b) of the present invention, and it is not limited to the above-mentioned method.

  The number average molecular weight of the urethane acrylate (b) of the present invention is preferably 1000 to 30000, more preferably 1000 to 10000. By setting it as 1000 or more, a softness | flexibility and toughness can be compatible, and favorable developability can be maintained by setting it as 30000 or less.

  The content of the urethane acrylate (b) of the present invention is preferably 10 to 40 wt%, more preferably 20 to 30 wt%, based on the ethylenically unsaturated compound (B). When it is 10 wt% or more, sufficient flexibility is obtained, and when it is 40 wt% or less, image reproducibility is improved.

  As the photopolymerization initiator (C) of the present invention, radicals are generated by self-decomposition by ultraviolet rays or hydrogen abstraction from other molecules, and a radical polymerization reaction is performed on a carbon-carbon unsaturated bond in an ethylenically unsaturated compound. Any known photopolymerization initiator can be used as long as it has a function of initiating the polymerization. Examples include acetophenones, benzoin ethers, benzophenones, thioxanthones, anthraquinones, benzyls, biacetyls and the like. These photopolymerization initiators can be used alone or in combination of two or more.

  Among the above photopolymerization initiators, specific examples of photopolymerization initiators preferably used in the present invention include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone and the like. can give.

  The content of the photopolymerization initiator (C) in the present invention is preferably 0.5 to 5 wt%, more preferably 1 to 3 wt% in the photosensitive resin composition. By setting it to 0.5 wt% or more, the photopolymerization reaction of the ethylenically unsaturated compound is sufficiently caused by actinic rays, and by setting it to less than 5 wt%, a sufficient drawing depth can be ensured.

  It is preferable to add a plasticizer for the purpose of imparting flexibility to the photosensitive resin composition of the present invention and improving compatibility. Specific examples of the plasticizer include polyhydric alcohols such as ethylene glycol, diethylene glycol, polyethylene glycol, glycerin, trimethylolpropane, and trimethylolethane, and alcohol amines such as diethanolamine and triethanolamine. Of these, diethylene glycol is preferably used from the viewpoints of flexibility and compatibility. These plasticizers can be used alone or in combination of two or more.

  The addition amount of the plasticizer in the present invention is preferably 5 to 25% by weight, more preferably 10 to 20% by weight. If it is 5 wt% or more, flexibility is imparted, and if it is 25 wt% or less, good image reproducibility and printability are maintained.

  A known polymerization inhibitor can be added to the photosensitive resin composition of the present invention for the purpose of ensuring thermal stability. Preferable polymerization inhibitors include phenols, catechols, hydroquinones, nitrosamines and the like.

  The addition amount of the polymerization inhibitor in the present invention is preferably in the range of 0.5 wt% or less. If it is 0.5 wt% or less, the ultraviolet curing of the photosensitive resin composition will not be affected.

  A surfactant can be added to the photosensitive resin composition of the present invention for the purpose of shortening the development time and preventing aggregation of the photosensitive resin component in the developer.

  As the surfactant in the present invention, a known surfactant can be used. For example, nonionic surfactants such as polyoxyalkylenes, anionic surfactants such as sulfonates, sulfates and phosphates, cationic surfactants such as amines, amphoteric surfactants, etc. Can be illustrated.

  The content of the surfactant in the present invention is preferably in the range of 0.001 to 5 wt%, more preferably 0.05 to 3 wt% in the photosensitive resin composition. Within this range, the purpose of shortening the development time and preventing aggregation of the photosensitive resin component in the developer can be achieved without deteriorating the image reproducibility.

  The photosensitive resin composition of the present invention further includes an antifoaming agent, an ultraviolet absorber, an oxygen scavenger, a sensitizer, and a colorant (dye, pigment, photochromic agent, color aid) for the purpose of improving various properties. , Fragrances, etc. can be added.

  As the support (D) of the present invention, a plastic sheet such as polyester, a synthetic rubber sheet such as styrene-butadiene rubber, a metal plate such as steel, stainless steel, and aluminum can be used. Among them, a plastic sheet such as polyester is preferably used from the viewpoint of flexibility, transparency, and dimensional stability, and a sheet of polyethylene terephthalate (hereinafter referred to as PET) is preferable from the viewpoint of heat resistance and chemical resistance.

  The thickness of the PET sheet is not particularly limited, but is preferably in the range of 100 to 350 μm from the viewpoints of handleability and flexibility. If it is 100 μm or more, handleability as a support can be secured, and if it is 350 μm or less, flexibility as a printing original plate is secured.

  The support (D) of the present invention is preferably subjected to an adhesion treatment for the purpose of improving the adhesion with the photosensitive resin layer (E). Examples of the method of adhesion treatment of the support surface include mechanical treatment such as sandblasting, physical treatment such as corona discharge, and chemical treatment such as coating. However, it is advisable to provide an easy adhesion layer by coating. It is preferable from the viewpoint.

    The photosensitive resin layer (E) of the present invention is composed of the photosensitive resin composition of the present invention, and the thickness of the photosensitive resin layer (E) is preferably 0.3 to from the viewpoint of printability and image reproducibility. It is 5 mm, more preferably in the range of 0.5 to 3 mm. If the photosensitive resin layer is 0.3 mm or more, a sufficient relief depth can be secured and a good printed matter can be obtained. If the photosensitive resin layer is 5 mm or less, ultraviolet rays reach the bottom of the relief and image reproducibility can be secured.

  In the photosensitive printing original plate of the present invention, the center angle of warpage of the printing plate after placing is preferably 180 ° or less, more preferably 90 ° or less. By setting the center angle of warpage of the printing plate after the plate setting to 180 ° or less, there is a problem that the printing plate is cracked by an external force when the printing plate is set on the plate cylinder, and the printing plate is removed from the plate cylinder. Problems such as floating can be prevented.

  The plate setting of the present invention is to leave a printing plate that has undergone a series of plate making steps (exposure, development, drying, post-exposure) at 25 ° C./50% RH for 7 days.

  In the photosensitive printing original plate of the present invention, the support (D), the photosensitive resin layer (E), and the cover film are preferably laminated in this order from the viewpoint of surface protection and prevention of adhesion of foreign matters and the like. The photosensitive resin layer (E) may be in direct contact with the cover film. For example, the photosensitive resin layer (E) is photosensitive for the purpose of imparting some characteristics, such as an anti-adhesion layer provided for the purpose of preventing adhesion of the photosensitive resin layer surface. One or more layers may be provided between the resin layer (E) and the cover film.

  Although it does not specifically limit as a material of a cover film, Plastic sheets, such as polyester and polyethylene, are used preferably. Although the thickness of a cover film is not specifically limited, The range of 10-150 micrometers is preferable from a viewpoint of handleability and cost. The cover film surface may be roughened for the purpose of improving the adhesion of the original film.

  In the photosensitive printing original plate of the present invention, the center angle of warpage of the printing original plate before exposure after peeling the cover film is preferably within ± 45 °, and more preferably within ± 30 °. By setting the center angle of warpage of the printing original plate before exposure to within ± 45 °, workability at the time of exposure using the original film is ensured, and even when a mask type CTP plate is used, the printing original plate Due to the warpage, ultraviolet rays do not enter vertically, and there is no possibility that image reproducibility is significantly impaired during exposure.

  In the present invention, the photosensitive resin composition contains the urethane (meth) acrylate (b) of the present invention as the ethylenically unsaturated compound (B), so that it can be used at any stage after engraving and plate making / plate setting. A photosensitive resin composition that does not warp the printing original plate or the printing plate, a photosensitive printing original plate having a photosensitive resin layer comprising the same, and a printing plate using the same can be obtained.

  The urethane (meth) acrylate (b) of the present invention is a compound having at least one urethane structure, polyoxyalkylene structure and ethylenically unsaturated group in the molecule. Since it has a urethane structure and a polyoxyalkylene structure, it is possible to impart flexibility to the photosensitive resin layer, relieve internal stress in accordance with changes in the humidity dimension of the photosensitive layer, and reduce warping of the printing original plate and printing plate. Furthermore, since the urethane (meth) acrylate (b) of the present invention is excellent in compatibility with the partially saponified polyvinyl acetate (a), it is possible to impart flexibility to the photosensitive resin layer more effectively. It can be estimated that the warpage of the plate can be reduced.

  The addition of flexibility to the photosensitive resin layer can also be achieved by adding a plasticizer such as polyethylene glycol, but simply adding a plasticizer reduces the crosslink density of the photosensitive resin layer, thereby reducing the water resistance during development. The image reproducibility is deteriorated. Since the urethane (meth) acrylate (b) of the present invention has an ethylenically unsaturated group in the molecule, the crosslinking density is maintained, and the urethane (meth) acrylate (b) is incorporated into a crosslinked structure by photocuring to give flexibility to the photosensitive resin layer. I can do it.

  In the photosensitive printing original plate of the present invention, the support (D), the photosensitive resin layer (E), and the ablation layer (F) are laminated in this order, so that the image reproducibility and the original film must be prepared and managed. This is preferable because it is eliminated.

  The ablation layer (F) of the present invention practically blocks ultraviolet light, efficiently absorbs infrared laser at the time of drawing, and partly or entirely is evaporated or ablated instantaneously by the heat. As a result, a difference occurs in the optical density between the laser irradiated portion and the unirradiated portion, and the same function as that of the conventional original image film can be achieved.

  As a preferred specific example of the ablation layer (F) of the present invention, a resin in which carbon black that absorbs infrared rays is dispersed can be exemplified. Although it does not specifically limit as a resin component used as a binder, A thermosetting resin can be used preferably from a stability and scratch resistant viewpoint of an ablation layer (F).

  The method for producing the ablation layer (F) is not particularly limited. For example, the ablation layer (F) can be produced by diluting a resin component in which carbon black is dispersed with an appropriate solvent, coating it, and drying the solvent.

  The photosensitive printing original plate of the present invention comprises an adhesive strength adjusting layer for the purpose of adjusting the adhesive strength between the photosensitive resin layer (E) and the ablation layer (F), and an interlayer between the ablation layer (F) and the cover film. Even if it has a peeling auxiliary layer for the purpose of adjusting the peelability, it can be used without any problem.

  As the method for producing the photosensitive resin composition of the present invention and the printing plate precursor using the same, usually, the water-soluble or water-swellable polymer (A) is heated and dissolved in a water / alcohol mixed solvent, and then ethylenically unsaturated. A compound (B), a photopolymerization initiator (C) and, if necessary, a plasticizer and other additives are added, and the mixture is stirred and mixed thoroughly to obtain a photosensitive resin composition solution. A photosensitive resin printing plate precursor can be obtained by casting this solution onto a support coated with an adhesive, drying the solvent, and then bringing the cover film coated with an anti-adhesion layer into close contact with the photosensitive layer. . Alternatively, a photosensitive resin printing plate precursor can be obtained by preparing a photosensitive resin sheet by dry film formation and laminating the photosensitive resin sheet between the support and the cover film.

  In order to form a relief image for printing using the above-mentioned photosensitive resin printing plate precursor, first, a negative or positive original image film is brought into close contact with the photosensitive resin layer from which the cover film has been peeled, or a mask type CTP. In the case of a plate, after the cover film is peeled off, laser drawing is performed, and then ultraviolet irradiation is performed with a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a xenon lamp, a carbon arc lamp, a chemical lamp, etc. Photocuring is performed by photopolymerization. In particular, when reproducibility of fine fine lines and independent points is required, it is possible to perform short-time exposure (back exposure) from the support side before peeling the cover film.

  Next, the photosensitive resin printing plate material is immersed in a developer, and a relief image is formed on the substrate by a brush type developing device that removes unpolymerized portions by rubbing with a brush. In addition to the brush type developing device, a spray type developing device can also be used. The liquid temperature during development is preferably 15 ° C to 40 ° C. After forming the relief image, the plate can be dried at 50 to 70 ° C. for about 5 to 15 minutes, and further subjected to actinic ray treatment in air or vacuum as necessary to obtain a printing plate.

  The photosensitive resin composition of the present invention can be used as a photosensitive resin layer for letterpress, planographic and intaglio printing, and a photosensitive printing original plate having a photosensitive resin layer comprising the photosensitive resin composition of the present invention is used for printing. In addition to reliefs, it can also be applied to stamps, seals, foil stamping, embossing, prototypes of molded products, master molds, and other applications.

Hereinafter, the present invention will be described in detail with reference to examples.

  (Synthesis Example 1: Synthesis of partially saponified polyvinyl acetate) “GOHSENOL KP-08R” manufactured by Nippon Synthetic Chemical Industry Co., Ltd. is swollen in acetone, and reacted with 1.0 mol% of succinic anhydride to react with it. Was added. This polymer was washed with acetone to remove unreacted succinic anhydride and dried. The acid value was measured to find that the acid value was 10.9.

  (Synthesis Example 2: Synthesis of Partially Saponified Polyvinyl Acetate) By using the same procedure as in Synthesis Example 1, partially saponified polyvinyl acetate “J Poval JR-05” manufactured by Nippon Acetate / Poval Co., Ltd. was used. 1.5 mol% was added and reacted to add a carboxyl group. When the acid value was measured, the acid value was 12.9.

  (Synthesis Example 3: Synthesis of polyamide) Equimolar salt of α, ω-diaminopolyoxyethylene and adipic acid obtained by adding acrylonitrile to both ends of polyethylene glycol having a number average molecular weight of 600 and reducing it with hydrogen 60 Parts by weight, 20 parts by weight of ε-caprolactam and 20 parts by weight of an equimolar salt of hexamethylenediamine and adipic acid were melt-polymerized under ordinary conditions to dissolve the relative viscosity (1 g of the polymer in 100 ml of chloral hydrate, at 25 ° C. A polyamide having a measurement of 2.50 was obtained.

(Characteristic evaluation of photosensitive printing original plate)
Center angle of warpage: A 10 × 10 cm photosensitive printing plate is placed on a horizontal base in a convex state, the height (x) and width (y) of the photosensitive printing plate shown in FIG. The central angle (θ) was calculated from the mathematical formula shown below.
^{r = (4x 2 + y 2} ) / 8x
θ = 2sin ⁻¹ (y / 2r) (when x ≦ r)
θ = 2 (180−sin ⁻¹ (y / 2r)) (when x> r)

  Center angle of warpage of the printing original plate before exposure: The cover film was peeled off from the photosensitive printing original plate of 10 × 10 cm, and measurement was performed according to the above-mentioned “center angle of warpage” measurement method.

  The center angle of warpage of the printing plate after placing the plate: The cover film was peeled off from the photosensitive printing original plate having a size of 10 × 10 cm, and the whole surface was exposed for 3 minutes with an ultraviolet low-pressure mercury lamp manufactured by Philips Electronics. Thereafter, it was washed out in neutral water at 25 ° C. for 3 minutes with a brush type developer, dried at 60 ° C. for 10 minutes, and then subjected to post-exposure for 3 minutes with the above-mentioned ultraviolet low pressure mercury lamp. After the treatment imitating the plate making process, the plate was left for 7 days at 25 ° C. and 50%, and measured according to the “center angle of warpage” measurement method described above.

  Plate surface adhesion: The plate surface of the printing plate used for the above-mentioned measurement of “center angle of warpage of the printing plate after placing” was pressed with a fingertip, and judged by the presence or absence of an adhesive feeling.

(Preparation of printing plate for evaluation in image reproducibility measurement of photosensitive resin printing original plate)
The photosensitive resin printing original plate is vacuum-adhered with a gray scale negative film for sensitivity measurement and a negative film for image reproducibility evaluation (150% 3% halftone dot, 150 μm independent point, 50 μm fine line, 300 μm wide open line), The exposure was performed with a UV low-pressure mercury lamp under the condition of gray scale sensitivity of 16 ± 1. Thereafter, development is carried out with a brush type developing device having a developer temperature of 25 ° C., drying at 60 ° C. for 10 minutes, and further post-exposure under the same conditions with a gray scale sensitivity of 16 ± 1 with an ultraviolet low-pressure mercury lamp, and a printing plate for evaluation Got.

  Development time: Development was carried out with a brush-type developing device having a developer temperature of 25 ° C., and the time required to remove the unexposed portion was measured and taken as the development time.

  Gray scale sensitivity: After preparing a printing plate for evaluation, the number of steps remaining without washing out the photosensitive resin was read.

Halftone dots: The periphery of 150% 3% of 1 × 1 cm was observed, and the superiority or inferiority due to the presence or absence of the lack of halftone dots was judged according to the following criteria.
○: No chipping △: Chipping at corners ×: Chipping at corners and sides

Thin line: A 50 μm wide thin line having a length of 1 cm was observed, and superiority or inferiority due to the presence or absence of bending was judged according to the following criteria.
○: No bend △: Slight bend ×: Bend

  Independent points: Three independent points of 150 μm were observed, and superiority or inferiority was judged based on the number of independent points reproduced.

  Line drawing depth: The line drawing depth at 300 μ width was measured by an enlargement projector.

Example 1
A water-soluble or water-swellable polymer shown in Table 1 and a plasticizer were dissolved in a mixed solvent of water / ethanol ratio = 55/45 (weight ratio) at 70 ° C. for 2 hours according to the addition amount shown in Table 2. Next, glycidyl methacrylate was added according to the addition amount shown in Table 2, and mixed at 70 ° C. for 0.5 hour. Further, various ethylenically unsaturated compounds, photopolymerization initiators, and additives (dyes, thermal polymerization inhibitors, ultraviolet absorbers) shown in Table 1 were added according to the addition amounts shown in Table 2, and mixed at 70 ° C. for 0.5 hours. A functional resin composition solution was obtained. At this time, it prepared so that the solid content concentration of the photosensitive resin composition solution might be 60 wt%.
When the solution was visually confirmed, no separation or turbidity of the solution was observed, and the solution was uniform.

  The obtained photosensitive resin composition solution was cast on a 0.19 mm thick polyester film coated with an adhesive and dried at 60 ° C. for 2.5 hours. At this time, the plate thickness after drying (polyester film + photosensitive layer) was adjusted to 1.14 mm. A mixed solvent of water / ethanol = 50/50 (weight ratio) is applied onto the photosensitive layer thus obtained, and a matted polyester film having an anti-adhesion layer on the surface is pressure-bonded to form a cover film. A photosensitive resin printing plate precursor was obtained.

  Table 3 shows the results of evaluating the characteristics of the obtained photosensitive resin printing plate precursor. The warping of the printing original plate was small, there was no plate surface adhesion, and the image reproducibility was good.

Examples 2-6, Comparative Examples 1-3
According to Table 1 and Table 2, it carried out similarly to Example 1, and obtained the photosensitive resin printing plate precursor.

  Table 3 shows the results of evaluating the characteristics of the obtained photosensitive resin printing plate precursor. In each of Examples 2 to 6, warpage was small, there was no plate surface adhesion, and image reproducibility was good.

  On the other hand, Comparative Examples 1 and 2 using polyamide as a water-soluble or water-swellable polymer had plate surface adhesion. Further, Comparative Example 3 containing no urethane (meth) acrylate had a large warpage.

It is the schematic which shows the evaluation method of the center angle of the curvature of the printing original plate obtained by the Example and the comparative example, and the printing plate after plate-setting.

Explanation of symbols

x: height of photosensitive printing plate y: width of photosensitive printing plate r: radius θ: central angle

Claims (8)

  A photosensitive resin composition containing a water-soluble or water-swellable polymer (A), an ethylenically unsaturated compound (B), and a photopolymerization initiator (C), wherein the water-soluble or water-swellable polymer (A) is A photosensitive resin composition comprising a partially saponified polyvinyl acetate (a), wherein the ethylenically unsaturated compound (B) contains a urethane (meth) acrylate (b).   The photosensitive resin composition according to claim 1, wherein the partially saponified polyvinyl acetate (a) has a saponification degree of 60 to 85 mol% and a polymerization degree of 300 to 1000.   The photosensitive resin composition according to claim 1 or 2, wherein the partially saponified polyvinyl acetate (a) has a reactive group capable of crosslinking with the ethylenically unsaturated compound (B).   The photosensitive resin composition according to claim 1, wherein the urethane (meth) acrylate (b) has a polyoxyalkylene structure.   A photosensitive printing original plate having at least a support (D) and a photosensitive resin layer (E), wherein the photosensitive resin layer (E) comprises the photosensitive resin composition according to any one of claims 1 to 4, A photosensitive printing original plate, wherein the center angle of warpage of the printing plate after placing is 180 ° or less.   A photosensitive printing original plate having at least a support (D) and a photosensitive resin layer (E), wherein the photosensitive resin layer (E) comprises the photosensitive resin composition according to any one of claims 1 to 4, A photosensitive printing original plate, wherein a central angle of warpage of the printing original plate before exposure is within ± 45 °.   The photosensitive printing original plate according to claim 5 or 6, further comprising an ablation layer (F).   A printing plate comprising the printing plate precursor according to any one of claims 5 to 7.

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