Photoresist printing original plate for relief printing

Abstract

Provided is a light-sensitive resin original printing plate for letterpress printing, the plate having excellent swelling resistance in relation to oil-based ink that includes an ester compound. A light-sensitive resin original printing plate for letterpress printing having a light-sensitive resin layer comprising a light-sensitive resin composition containing at least: (A) a polymer compound; (B) a dibasic acid diester; (C) a photopolymerizable compound; and (D) a photopolymerization initiator, wherein said light-sensitive resin original printing plate for letterpress printing is characterized in that the dibasic acid diester (B) content of the light-sensitive resin composition is 2.5-15 mass%. (In the formula, R1 represents a C2-8 divalent aliphatic hydrocarbon group, a C6-14 divalent aromatic hydrocarbon group, or a C4-14 divalent aliphatic cyclic hydrocarbon group, and R2 and R3 may be the same or different, and each represents a C1-12 straight-chain or branched-chain aliphatic hydrocarbon group.)

Description

Technical Field

[0001] The present invention relates to a photosensitive resin printing original plate for relief printing, which has excellent swelling resistance to oil-based ink, and particularly relates to a photosensitive resin printing original plate for relief printing, which has excellent swelling resistance to oil-based ink containing an ester compound used for printing cloth tags.

Background Art

[0002] As a method for developing a printing original plate to produce a printing plate, a method using a developer composed of an organic solvent has been conventionally used. However, due to problems in the working environment, a method of developing with an aqueous developer obtained by adding a surfactant or the like to water to produce a printing plate has been proposed (see, for example, Patent Documents 1 to 3).

[0003] These conventional proposals generally disclose that by incorporating a plasticizer into the printing original plate, the hardness can be reduced and the resilience modulus can be improved. However, on the other hand, when a plasticizer is incorporated, the mechanical strength of the resulting printing plate becomes insufficient, and there are problems with printing durability such as cracking of the printing plate and loss of relief images during long-run printing.

[0004] In addition, in the application of printing cloth tags, an oil-based ink containing an ester compound is used. However, conventional printing plates have a problem that they absorb the ink and swell during printing, and when long-run printing is performed, the line thickness of the printed matter increases.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made to solve such problems of the prior art, and an object thereof is to provide a photosensitive resin printing plate for relief printing excellent in swelling resistance to oil-based ink, and particularly to provide a photosensitive resin printing plate for relief printing excellent in swelling resistance to oil-based ink containing an ester compound.

Means for Solving the Problems

[0007] As a result of intensive studies to achieve such an object, the present inventor has found that a printing plate excellent in swelling resistance to oil-based ink can be obtained by containing a specific amount of dibasic acid diester in the photosensitive resin layer constituting the printing plate, and has completed the present invention.

[0008] That is, the present invention has the following configurations (1) to (6). (1) A photosensitive resin printing plate for relief printing having a photosensitive resin layer composed of a photosensitive resin composition containing at least a polymer compound (A), a dibasic acid diester (B) represented by the following general formula (I), a photopolymerizable compound (C), and a photopolymerization initiator (D), wherein the content of the dibasic acid diester (B) in the photosensitive resin composition is 2.5 to 15% by mass. TIFF0007700781000001.tif27137(In the formula, R 1 represents a divalent aliphatic hydrocarbon group having 2 to 8 carbon atoms, a divalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a divalent alicyclic hydrocarbon group having 4 to 14 carbon atoms, and R 2 and R 3 may be the same or different from each other and represent a linear or branched aliphatic hydrocarbon group having 1 to 12 carbon atoms.) (2) The dibasic acid diester (B) is at least one selected from the group consisting of succinic acid diester, glutaric acid diester, adipic acid diester, pimelic acid diester, suberic acid diester, azelaic acid diester, sebacic acid diester, and phthalic acid diester. The photosensitive resin printing original plate for letterpress printing according to (1). (3) The photosensitive resin printing original plate for letterpress printing according to (1) or (2), wherein the polymer compound (A) is a latex having a butadiene skeleton and / or an isoprene skeleton. (4) The latex is a polybutadiene latex, a styrene-butadiene copolymer latex, an acrylonitrile-butadiene copolymer latex, a methyl methacrylate-butadiene copolymer latex, a polyisoprene latex, or a latex obtained by further copolymerizing acrylic acid or methacrylic acid with the copolymer latex. The photosensitive resin printing original plate for letterpress printing according to (3). (5) The latex is at least one aqueous dispersion latex selected from the group consisting of a polybutadiene latex, a styrene-butadiene copolymer latex, an acrylonitrile-butadiene copolymer latex, a methyl methacrylate-butadiene copolymer latex, and a latex obtained by further copolymerizing acrylic acid or methacrylic acid with the copolymer latex. The photosensitive resin printing original plate for letterpress printing according to (4). (6) The photosensitive resin printing original plate for letterpress printing according to (1) or (2), wherein the polymer compound (A) is a polyamide resin composed of polyamide and / or polyamide block copolymer, and / or a partially saponified polyvinyl acetate resin. [Advantages of the Invention]

[0009] According to the present invention, even when an oil-based ink containing an ester compound is used, swelling of the printing plate due to ink absorption is small, and thus a photosensitive resin printing original plate for letterpress printing in which almost no line thickening of the image of the printed matter occurs even during long-run printing can be provided. [Embodiments for Carrying Out the Invention]

[0010] The photosensitive resin printing original plate for relief printing of the present invention has a photosensitive resin layer composed of a photosensitive resin composition containing at least a polymer compound (A), a dibasic acid diester (B) represented by the following general formula (I), a photopolymerizable compound (C), and a photopolymerization initiator (D). Hereinafter, each component of the photosensitive resin composition will be described.

[0011] The polymer compound (A) is not particularly limited as long as it is used in this field. However, from the viewpoint of suitability as a relief printing original plate, (i) a latex having a butadiene skeleton and / or an isoprene skeleton, (ii) a polyamide resin composed of a polyamide and / or a polyamide block copolymer, and / or (iii) a partially saponified polyvinyl acetate resin is preferable.

[0012] (i) As the latex having a butadiene skeleton and / or an isoprene skeleton, it may be appropriately selected from conventionally known latices. For example, polybutadiene latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, polyisoprene latex, etc. can be used. These latices may be modified with (meth)acrylic, carboxy, silicone, fluorine, etc. as desired. In addition, as these latices, a number of various synthetic latices and natural latices are commercially available, so an appropriate one can be selected from them.

[0013] Among these, a water-dispersed latex containing a butadiene skeleton in the molecular chain is preferably used from the viewpoints of hardness and rubber elasticity. Specific examples of such water-dispersed latexes include polybutadiene latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, and copolymer latexes obtained by copolymerizing the above copolymers with acrylic acid or methacrylic acid. Polybutadiene latex and acrylonitrile-butadiene copolymer latex are more preferred.

[0014] (ii) A polyamide resin composed of a polyamide and / or a polyamide block copolymer can be a high molecular compound containing 50% by mass or more, preferably 70% by mass or more, of structural units composed of amide bonds in the molecule in a block form. Examples include polyether amide, polyether ester amide, tertiary nitrogen-containing polyamide, ammonium salt type tertiary nitrogen atom-containing polyamide, and addition polymers of amide compounds having one or more amide bonds and organic diisocyanate compounds. Among them, ammonium salt type tertiary nitrogen atom-containing polyamide is preferred. Further, when a tertiary nitrogen atom-containing polyamide and an ammonium salt type tertiary nitrogen atom-containing polyamide are contained, the developability is improved by containing an organic acid. Examples of the organic acid include acetic acid, lactic acid, and methacrylic acid, but are not limited thereto.

[0015] (iii) The partially saponified polyvinyl acetate resin is not particularly limited as long as it is used in this field. From the viewpoint of the image reproducibility of the relief printing plate, a partially saponified polyvinyl acetate resin having a saponification degree of 70 to 95 mol% and an average degree of polymerization of 1500 to 3400 is preferred.

[0016] The compounding amount of the high molecular compound (A) is preferably 30 to 80% by mass, more preferably 40 to 75% by mass, in the photosensitive resin composition. If it is less than the above lower limit, the strength of the printing plate may be insufficient, and if it exceeds the above upper limit, it may take time for water development.

[0017] The dibasic acid diester (B) is a compound obtained by esterifying an organic acid having a structure capable of separating two protons in water, and specifically, it is a compound represented by the following general formula (I). TIFF0007700781000002.tif27137(In the formula, R 1 represents a divalent aliphatic hydrocarbon group having 2 to 8 carbon atoms, a divalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a divalent alicyclic hydrocarbon group having 4 to 14 carbon atoms, and R 2 and R 3 may be the same as or different from each other, and represent a linear or branched aliphatic hydrocarbon group having 1 to 12 carbon atoms.)

[0018] Specific examples of the dibasic acid diester having such a structure include dimethyl oxalate, dimethyl malonate, dimethyl succinate, dimethyl glutarate, dimethyl tartrate, dimethyl adipate, dimethyl glutamate, dimethyl sebacate, dimethyl hexafluorosilicate, diethyl oxalate, diethyl malonate, diethyl succinate, diethyl glutarate, diethyl tartrate, diethyl adipate, diethyl glutamate, diethyl sebacate, diethyl hexafluorosilicate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, bis(2-ethylhexyl) phthalate, diisononyl phthalate, ethyl phthalyl ethyl glycolate, dibutyl adipate, diisobutyl adipate, bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis[2-(2-butoxyethoxy)ethyl] adipate, bis(2-ethylhexyl) azelate, dibutyl sebacate, and the like. These may be used alone or in combination of two or more thereof.

[0019] Among these, succinic acid diesters, glutaric acid diesters, adipic acid diesters, pimelic acid diesters, suberic acid diesters, azelaic acid diesters, sebacic acid diesters, and phthalic acid diesters are preferred.

[0020] By incorporating such a dibasic acid diester into the photosensitive resin layer, a printing plate excellent in swelling resistance to an oil-based ink containing an ester compound can be obtained. In particular, the swelling of the printing plate is caused by the absorption of the ester compound in the oil-based ink containing an ester compound into the photosensitive resin layer during printing. However, by containing a dibasic acid diester, the absorption of the ester compound can be suppressed.

[0021] The blending amount of the dibasic acid diester (B) needs to be 2.5 to 15% by mass in the photosensitive resin composition, preferably 3.0 to 10% by mass. Since the dibasic acid diester has an effect of suppressing the phenomenon in which the ester compound contained in the oil-based ink is absorbed into the photosensitive resin layer, if it is less than the above lower limit, the swelling resistance to the oil-based ink is poor. On the other hand, if it exceeds the above upper limit, the printing durability during long-run printing deteriorates due to the deterioration of physical properties caused by the dibasic acid diester, which is not preferable.

[0022] The photopolymerizable compound (C) is preferably a photopolymerizable oligomer, and in particular, it is a conjugated diene-based ethylenic polymer in which an ethylenically unsaturated group is bonded to the terminal and / or side chain of a conjugated diene-based polymer, and preferably has a number average molecular weight of 500 or more and 10,000 or less.

[0023] The conjugated diene polymer that constitutes the conjugated diene-based ethylene 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. Examples of such a homopolymer of a conjugated diene unsaturated compound or a copolymer of a conjugated diene unsaturated compound and a monoethylenically unsaturated compound include butadiene polymers, isoprene polymers, chloroprene polymers, styrene-chloroprene copolymers, acrylonitrile-butadiene copolymers, acrylonitrile-isoprene copolymers, methyl methacrylate-isoprene copolymers, acrylonitrile-isoprene copolymers, methyl methacrylate-isoprene copolymers, methyl methacrylate-chloroprene copolymers, methyl acrylate-butadiene copolymers, methyl acrylate-isoprene copolymers, methyl acrylate-chloroprene copolymers, methyl acrylate-chloroprene copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-chloroprene-styrene copolymers, etc. These are mentioned. Among these, in terms of rubber elasticity and photocurability, butadiene polymers, isoprene polymers, and acrylonitrile-butadiene copolymers are preferable, and butadiene polymers and isoprene polymers are particularly preferable.

[0024] The method for introducing terminal and / or side-chain ethylenically unsaturated groups into the conjugated diene polymer is not particularly limited. For example, (i) a monoethylenically unsaturated carboxylic acid such as (meth)acrylic acid is ester-bonded to the hydroxyl group at the terminal of a hydroxyl group-terminated conjugated diene polymer obtained using hydrogen peroxide as a polymerization initiator by a dehydration reaction, or a monoethylenically unsaturated carboxylic acid alkyl ester such as methyl (meth)acrylate or ethyl (meth)acrylate is ester-bonded by a transesterification reaction, (ii) a method of reacting an ethylenically unsaturated alcohol such as allyl alcohol or vinyl alcohol with a conjugated diene polymer obtained by copolymerizing a conjugated diene compound and an ethylenically unsaturated compound containing at least partially an unsaturated carboxylic acid (ester), etc. can be mentioned.

[0025] As the photopolymerizable compound (C) component, in addition to the above-described photopolymerizable oligomer, alkyl methacrylate can be used. As the alkyl methacrylate, those having 8 to 18 carbon atoms and being linear are preferred.

[0026] Specifically, 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, stearyl (meth)acrylate, cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, halogenated alkyl (meth)acrylates such as chloroethyl (meth)acrylate, chloropropyl (meth)acrylate, alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, phenoxyalkyl (meth)acrylates such as phenoxyethyl (meth)acrylate, nonylphenoxyethyl (meth)acrylate, etc. can be mentioned. Particularly preferred are n-lauryl methacrylate, alkyl (C12-13) methacrylate, tridecyl methacrylate, alkyl (C12-15) methacrylate, etc.

[0027] The blending amount of the photopolymerizable compound (C) is preferably 5 to 70% by mass, more preferably 10 to 60% by mass in the photosensitive resin composition. If it is less than the above lower limit, the time required for curing by ultraviolet irradiation may become extremely long. If it exceeds the above upper limit, the depth of concave lines, concave characters, etc. may become extremely shallow.

[0028] As the photoinitiator (D), any conventionally known one can be used as long as it can polymerize polymerizable carbon-carbon unsaturated groups by light, and those having a function of generating radicals by self-decomposition or hydrogen abstraction by light absorption are preferably used. For example, benzoin alkyl ethers, benzophenones, anthraquinones, benzyls, acetophenones, diacetyls, etc. can be mentioned. The blending amount of the photoinitiator (D) is preferably in the range of 0.1 to 50 parts by mass, more preferably in the range of 0.3 to 10 parts by mass, based on 100 parts by mass of the polymer compound (A). If it is less than the above lower limit, the initiation efficiency may decrease and the image reproducibility may be poor. If it exceeds the above upper limit, the sensitivity may be too high and it may be difficult to control the exposure time.

[0029] A plasticizer can also be added to the photosensitive resin composition. The plasticizer is not particularly limited as long as it generally has the property of softening the plate material, but those having good compatibility with the polymer compound (A) and the photopolymerizable compound (C) are preferred.

[0030] In addition, in order to improve the thermal stability of the photosensitive resin composition, a conventionally known polymerization inhibitor can be added to the photosensitive resin composition. Preferred polymerization inhibitors include phenols, hydroquinones, catechols, etc. These blending amounts are generally used in the range of 0.001 to 5% by mass based on the whole photosensitive resin composition.

[0031] Moreover, other optional components include dyes, pigments, viscosity modifiers, defoamers, ultraviolet absorbers, fragrances, anti-aggregation agents, surfactants, etc.

[0032] Next, the method for manufacturing the printing original plate of the present invention will be described. First, each of the above-described components is prepared and mixed to produce a photosensitive resin composition. Next, the obtained photosensitive resin composition is formed into a layer to obtain a photosensitive resin layer. Specifically, after mixing the components of the photosensitive resin composition using an extruder, kneader, etc., a method of forming a photosensitive resin layer having a desired thickness by hot press molding, calendering, or extrusion molding can be mentioned. In the obtained photosensitive resin layer, in order to maintain the accuracy as a printing plate, a support such as polyester may be provided on the side opposite to the relief surface. Further, since the photosensitive resin layer may exhibit adhesiveness depending on its composition, in order to improve the contact with the transparent image carrier (negative film) laminated thereon and to enable the reuse of the image carrier, a water-based developable flexible film layer may be provided on its surface. These supports and flexible film layers can be adhered to the photosensitive resin layer by roll lamination after sheet molding. Also, a highly accurate photosensitive resin layer can be obtained by heating and pressing after lamination.

[0033] Next, the method for obtaining a printing plate from the printing original plate of the present invention will be described. First, the photosensitive resin layer in the printing original plate of the present invention is irradiated with light through a transparent image carrier, and the irradiated portion is photocured to form an image. Then, the unirradiated portion is removed (developed) using an aqueous developer to obtain a relief (printing plate).

[0034] Examples of the active light source used for photocuring 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, sunlight, and the like.

[0035] As the aqueous developer, water alone or a composition obtained by adding a surfactant such as nonionic or anionic surfactant, a pH adjuster, a cleaning aid, etc. to water as needed can be used.

[0036] Specific examples of nonionic surfactants include polyoxyalkylene alkyl or alkenyl ethers, polyoxyalkylene alkyl or alkenyl phenyl ethers, polyoxyalkylene alkyl or alkenyl amines, polyoxyalkylene alkyl or alkenyl amides, ethylene oxide / propylene oxide block adducts, and the like. Specific examples of anionic surfactants include linear alkylbenzene sulfonates having an alkyl group with an average carbon number of 8 to 16, α-olefin sulfonates having an average carbon number of 10 to 20, dialkyl sulfosuccinates having an alkyl or alkenyl group with a carbon number of 4 to 10, sulfonates of fatty acid lower alkyl esters, alkyl sulfates having an average carbon number of 10 to 20, alkyl ether sulfates having a linear or branched alkyl or alkenyl group with an average carbon number of 10 to 20 and having an average of 0.5 to 8 moles of ethylene oxide added thereto, saturated or unsaturated fatty acid salts having an average carbon number of 10 to 22, and the like.

[0037] Examples of pH adjusters include sodium borate, sodium carbonate, sodium silicate, sodium metasilicate, sodium succinate, sodium acetate, and the like. Among these, sodium silicate is preferred in terms of solubility in water.

[0038] Examples of cleaning aids include amines such as monoethanolamine, diethanolamine, and triethanolamine, ammonium salts such as tetramethylammonium hydroxide, and paraffinic hydrocarbons. The cleaning aid can enhance the cleaning ability when used in combination with the above surfactants and pH adjusters.

[0039] These surfactants, pH adjusters, and cleaning aids are added and mixed with water in an appropriate mixing ratio in the range of 0.1 to 50% by mass, preferably 1 to 10% by mass, and used.

[0040] After development, it is common to dry the plate in an oven at about 60°C for 15 to 120 minutes.

[0041] Depending on the composition of the photosensitive resin composition that constitutes the photosensitive resin layer, stickiness may remain on the plate surface even after drying. In that case, the stickiness can be removed by a known surface treatment method. As the surface treatment method, exposure treatment with actinic rays having a wavelength of 300 nm or less is desirable.

[0042] The photosensitive resin composition of the present invention is most suitably used for letterpress printing using an oil-based ink containing an ester compound, such as printing of cloth tags, but is not limited to this application, and can also be used for flexographic printing, lithographic printing, gravure printing, screen printing, and as a photoresist.

Examples

[0043] The effects of the present invention are shown by the following examples, but the present invention is not limited thereto. In the examples, "parts" means parts by mass, and the numerical values indicating the composition ratios in the table also mean parts by mass.

[0044] Examples 1 to 11, Comparative Examples 1 to 3 (Examples using latex as the polymer compound (A)) Each component was blended so as to have the blending composition (parts by mass) shown in Table 1, and the photosensitive resin compositions of Examples 1 to 11 and Comparative Examples 1 to 3 were prepared by kneading in a kneader at 100°C.

[0045]

Table 1

[0046] Details of each blending component used in Table 1 are as follows. Polymeric compound (A) · Butadiene latex (Nipol LX111NF, non-volatile content 55%, manufactured by Nippon Zeon Co., Ltd.) · Acrylonitrile-butadiene latex (Nipol SX1503, non-volatile content 42%, manufactured by Nippon Zeon Co., Ltd.) Dibasic acid diester (B) · Dimethyl succinate (manufactured by Tokyo Chemical Industry Co., Ltd.) ·Dimethyl Glutarate (manufactured by Tokyo Chemical Industry Co., Ltd.) ·Dimethyl Adipate (manufactured by Tokyo Chemical Industry Co., Ltd.) ·Dimethyl Pimelate (manufactured by Tokyo Chemical Industry Co., Ltd.) ·Dimethyl Suberate (manufactured by Tokyo Chemical Industry Co., Ltd.) ·Dimethyl Azelate (manufactured by Tokyo Chemical Industry Co., Ltd.) ·Dimethyl Sebacate (manufactured by Tokyo Chemical Industry Co., Ltd.) ·Dimethyl Phthalate (manufactured by Tokyo Chemical Industry Co., Ltd.) ·Bis(2-ethylhexyl) Adipate (manufactured by Tokyo Chemical Industry Co., Ltd.) Photopolymerizable compound (C) ·Oligobutadiene Acrylate (manufactured by Kyoeisha Chemical Co., Ltd., ABU-4) ·Lauryl Methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., Light Ester L) ·Dimethyloltricyclodecane Diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., Light Acrylate DCP-A) Photopolymerization initiator (D) ·Benzyl Dimethyl Ketal (manufactured by Tokyo Chemical Industry Co., Ltd.) Other components ·Hydroquinone Monomethyl Ether (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0047] The photosensitive resin compositions of each of the thus obtained examples and comparative examples were sandwiched between a film having a polyester-based adhesive layer coated on a polyethylene terephthalate film with a thickness of 125 μm and a film having an anti-adhesive layer (polyvinyl alcohol) coated on the same polyethylene terephthalate film, such that the adhesive layer and the anti-adhesive layer were in contact with the photosensitive resin composition, and were pressed at 105 °C and a pressure of 100 kg / cm 2 for 1 minute, thereby producing a printing original plate having a photosensitive resin layer with a total thickness of 1.825 mm and a thickness of 1.7 mm.

[0048] Next, with respect to the produced printing original plate, an illuminance of 17.5 W / m at 365 nm 2Using an ultraviolet lamp (Anderson & Vreeland lamp FR20T12 - BL - 9 - BP), back exposure was performed from the base side so that the relief depth became 0.8 mm. Then, a negative film containing images of the letter T in 3 - point, 5 - point, and 10 - point boldface alphabets and solid images was applied to the original plate, and a step guide was applied. Main exposure was performed so that the step guide reproduced 15 steps. Then, the negative film was removed, and development was carried out for 8 minutes in neutral water at 40 °C containing 4 mass% of sodium alkylnaphthalenesulfonate, followed by drying at 60 °C for 10 minutes. Then, post - exposure was performed for 5 minutes using the same ultraviolet lamp. Then, the surface was treated by irradiating with a germicidal lamp for 5 minutes to obtain a relief for evaluation.

[0049] Examples 12 - 21, Comparative Examples 4 - 6 (Examples using polyamide resin or partially saponified polyvinyl acetate resin as the polymer compound (A)) Each component was blended into a kettle so as to have the composition (parts by mass) shown in Table 2, and concentration was carried out until the temperature in the kettle reached 110 °C to prepare the photosensitive resin compositions of Examples 12 - 21 and Comparative Examples 4 - 6.

[0050]

Table 2

[0051] Details of each component used in Table 2 are as follows. Polymeric compound (A) ·Polymer 1 synthesized by the following procedure ·Polymer 2 synthesized by the following procedure ·Partially saponified polyvinyl acetate (Gosenol TM KH - 17, manufactured by Mitsubishi Chemical Corporation, saponification degree 78.5 - 81.5%, average degree of polymerization 1700) Dibasic acid diester (B) ·Dimethyl succinate (manufactured by Tokyo Chemical Industry Co., Ltd.) ·Dimethyl glutarate (manufactured by Tokyo Chemical Industry Co., Ltd.) ·Dimethyl adipate (manufactured by Tokyo Chemical Industry Co., Ltd.) ·Dimethyl pimelate (manufactured by Tokyo Chemical Industry Co., Ltd.) · Dimethyl suberate (manufactured by Tokyo Chemical Industry Co., Ltd.) · Dimethyl azelate (manufactured by Tokyo Chemical Industry Co., Ltd.) · Dimethyl sebacate (manufactured by Tokyo Chemical Industry Co., Ltd.) · Dimethyl phthalate (manufactured by Tokyo Chemical Industry Co., Ltd.) · Bis(2-ethylhexyl) adipate (manufactured by Tokyo Chemical Industry Co., Ltd.) Photopolymerizable compound (C) · Acrylic acid adduct of propylene glycol diglycidyl ether (Epoxy Ester 70PA, manufactured by Kyoeisha Chemical Co., Ltd.) · Glycerol dimethacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) · Tetrahydrofurfuryl methacrylate (Light Ester THF(1000), manufactured by Kyoeisha Chemical Co., Ltd.) Photopolymerization initiator (D) · Benzyl dimethyl ketal (manufactured by Tokyo Chemical Industry Co., Ltd.) Other components · Diethylene glycol (manufactured by Tokyo Chemical Industry Co., Ltd.) · N-Ethyltoluenesulfonamide (manufactured by Tokyo Chemical Industry Co., Ltd.) · Lactic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) · Pentaerythritol polyoxyethylene ether (manufactured by Nippon Emulsifier Co., Ltd.) · 1,4-Naphthoquinone (manufactured by Tokyo Chemical Industry Co., Ltd.) · Hydroquinone monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0052] (Synthesis of Polymer 1) 50 parts of ε-caprolactam, 56 parts of N,N'-bis(γ-aminopropyl)piperazine adipate, 6.3 parts of 1,3-bisaminomethylcyclohexane adipate and 10 parts of water were put into a reactor. After sufficient nitrogen substitution, the reactor was sealed and gradually heated. When the internal pressure reached 10 kg / cm 2When the pressure reached [pressure value], the water in the reactor was gradually distilled off to return to normal pressure in 1 hour, and then reacted at normal pressure for 1.0 hour. The maximum polymerization temperature was 220 °C. As a result, a transparent pale yellow alcohol-soluble oligomer with a specific viscosity of 1.5, substantially primary amino groups at both ends, and an amide bond bonded in a block form with a number average molecular weight of about 3,000 was obtained. After dissolving 46 parts of this oligomer in 200 parts of methanol, 9 parts of an organic diisocyanate compound having isocyanate groups substantially at both ends obtained by reacting 1000 parts of polypropylene glycol (weight average molecular weight: 1000) and 369 parts of hexamethylene diisocyanate was gradually added with stirring. The reaction between the two was completed at 65 °C in about 15 minutes. This solution was placed in a Teflon (registered trademark)-coated petri dish, methanol was evaporated and removed, and then dried under reduced pressure to obtain a polyamide block copolymer (Polymer 1). This polyamide block copolymer had a specific viscosity of 2.0 and contained 82% by mass of a block component of a structural unit composed of an amide bond, and was a high molecular compound containing a urea bond and a urethane bond in addition to the amide bond.

[0053] (Synthesis of Polymer 2) 55 parts of ε-caprolactam, 40 parts of N,N'-bis(γ-aminopropyl)piperazine adipate, 7.5 parts of 1,3-bisaminomethylcyclohexane adipate and 100 parts of water were put into a reactor, and after sufficient nitrogen substitution, it was sealed and gradually heated. When the internal pressure reached 10 kg / cm 2 At that time, the water in the reactor was gradually distilled off to return to normal pressure in 1 hour, and then reacted at normal pressure for 1.0 hour to obtain a polyamide (Polymer 2). The specific viscosity of this polyamide was 2.4, and it was a high molecular compound composed only of amide bonds.

[0054] The photosensitive resin compositions of each of the obtained examples and comparative examples were sandwiched between a film obtained by coating a polyester-based adhesive layer on a polyethylene terephthalate film with a thickness of 125 μm and a film obtained by coating an anti-adhesive layer (polyvinyl alcohol) on the same polyethylene terephthalate film so that the adhesive layer and the anti-adhesive layer were in contact with the photosensitive resin composition, and a printing original plate having a photosensitive resin layer with a total laminator thickness of 1.825 mm and a thickness of 1.7 mm was produced.

[0055] Next, with respect to the produced printing original plate, using an ultraviolet lamp (lamp FR20T12-BL-9-BP manufactured by Anderson&Vreeland) with an illuminance of 17.5 W / m 2 at 365 nm, back exposure was performed from the base side so that the relief depth became 0.8 mm. Then, a negative film including images of the letter T in 3-point, 5-point, and 10-point boldface alphabets and a solid image, and a step guide were applied to the original plate, and main exposure was performed so that the step guide was reproduced in 15 steps. Then, the negative film was removed, developed with tap water at 25°C for 3 minutes, and dried with warm air at 70°C for 10 minutes. Then, post-exposure was performed for 2 minutes using the same ultraviolet lamp to obtain a relief for evaluation.

[0056] The evaluation of the printing original plates obtained from the photosensitive resin compositions of each of the examples and comparative examples was performed for image reproducibility, printability (line thickness), and printing durability (relief chipping resistance) using the relief for evaluation. The results are shown in Table 3. Note that the printability (line thickness) and printing durability (relief chipping resistance) were evaluated for both the case of tag printing using an oil-based ink containing an ester compound and the case of flexographic printing using an aqueous ink. The specific evaluation procedure is as follows.

[0057] (Image reproducibility) The image reproducibility was evaluated by the smallest point of the boldface characters that could be reproduced. Specifically, those in which 3-point boldface characters could be reproduced were indicated as 〇, those in which 5-point boldface characters could be reproduced were indicated as △, those in which 10-point boldface characters could be reproduced were indicated as ×, and those in which 10-point characters could not be reproduced were indicated as ××.

[0058] (Printability and printing durability in the case of tag printing) The relief for evaluation was printed using a tag printing machine (Shanghai Huanye Machine PT 2 / 1). Specifically, Fabrifast MIXING BLACK (ink containing dimethyl succinate, dimethyl adipate, and dimethyl glutarate) manufactured by Perfectos was used as the oil-based ink, and Nylon Taffeta was used as the substrate for 8000 m (50000 shots) of printing. (Printability) The evaluation of printability (line thickness) was performed based on the ratio of the vertical line width of the 5-pt T character of the printed matter after 100 shots and the printed matter after 50000 shots. Specifically, those with a line width ratio of 1.0 or more and less than 1.5 were marked as 〇, those with a line width ratio of 1.5 or more and less than 2.0 were marked as △, those with a line width ratio of 2.0 or more were marked as ×, and the relief that could not be printed was marked as ××.

[0059] (Printing durability) The evaluation of printing durability (chip resistance of the relief) was determined by the presence or absence of chips in the relief after 50000 shots of printing. Specifically, those without chips in the relief were marked as 〇, and those with chips in the relief were marked as ×.

[0060] (Printability and printing durability in the case of flexographic printing) The relief for evaluation was printed using a flexographic printing machine (manufactured by M.C. Co., Ltd.: FPR302). Specifically, ROBOT INK (ink containing propyl acetate) manufactured by Inktech Limited was used as the oil-based ink, and PPC50 / OPT1 / GB82 manufactured by Oji Tack Co., Ltd. was used as the substrate for 8000 m (50000 shots) of printing. (Printability) The evaluation of printability (line thickness) was performed based on the ratio of the vertical line width of the 5-pt T character of the printed matter after 100 shots and the printed matter after 50000 shots. Specifically, those with a line width ratio of 1.0 or more and less than 1.5 were marked as 〇, those with a line width ratio of 1.5 or more and less than 2.0 were marked as △, those with a line width ratio of 2.0 or more were marked as ×, and the relief that could not be printed was marked as ××.

[0061] (Print durability) The evaluation of print durability (chipping resistance of the relief) was determined by the presence or absence of chipping of the relief after 50,000 shots of printing. Specifically, those without chipping on the relief were marked as 〇, and those with chipping on the relief were marked as ×.

[0062]

Table 3

[0063] As can be seen from Table 3, all of Examples 1 to 21 that meet the requirements of the present invention are excellent in image reproducibility, printability (line thickness), and print durability (chipping resistance of the relief). On the other hand, Comparative Examples 1 and 4 that do not contain dibasic acid diester (B) at all, and Comparative Examples 2 and 5 with too little content of dibasic acid diester (B) are inferior in printability (line thickness). Comparative Examples 3 and 6 with too much content of dibasic acid diester (B) are inferior in print durability (chipping resistance of the relief).

Industrial applicability

[0064] The printing plate obtained from the photosensitive resin printing original plate for letterpress printing of the present invention has little swelling of the printing plate due to ink absorption even when using an oil-based ink containing an ester compound. Therefore, even when long-run printing is performed, almost no change in the line thickness of the image of the printed matter occurs. Therefore, the present invention enables long-run printing in flexographic printing including tag printing and is expected to make a great contribution to the industry.

Claims

A photosensitive resin printing plate for relief printing using an oil-based ink containing a dibasic acid diester compound, wherein the photosensitive resin printing plate for relief printing has a photosensitive resin layer composed of a photosensitive resin composition containing at least a polymer compound (A), a dibasic acid diester (B) represented by the following general formula (I), a photopolymerizable compound (C), and a photoinitiator (D), and the content of the dibasic acid diester (B) in the photosensitive resin composition is 2.5 to 15% by mass. (In the formula, R1 represents a divalent aliphatic hydrocarbon group having 2 to 8 carbon atoms, a divalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a divalent alicyclic hydrocarbon group having 4 to 14 carbon atoms; R2 and R3 may be the same or different from each other and each represents a linear or branched aliphatic hydrocarbon group having 1 to 12 carbon atoms.) The photosensitive resin printing plate for relief printing according to claim 1, wherein the dibasic acid diester (B) is at least one selected from the group consisting of succinic acid diester, glutaric acid diester, adipic acid diester, pimelic acid diester, suberic acid diester, azelaic acid diester, sebacic acid diester, and phthalic acid diester. The photosensitive resin printing plate for relief printing according to claim 1 or 2, wherein the polymer compound (A) is a latex having a butadiene skeleton and / or an isoprene skeleton.

4. The photosensitive resin printing plate for relief printing according to claim 3, wherein the latex is a polybutadiene latex, a styrene-butadiene copolymer latex, an acrylonitrile-butadiene copolymer latex, a methyl methacrylate-butadiene copolymer latex, a polyisoprene latex, or a latex obtained by further copolymerizing acrylic acid or methacrylic acid with the copolymer latex.

5. The photosensitive resin printing plate for relief printing according to claim 4, wherein the latex is at least one aqueous dispersion latex selected from the group consisting of a polybutadiene latex, a styrene-butadiene copolymer latex, an acrylonitrile-butadiene copolymer latex, a methyl methacrylate-butadiene copolymer latex, and a latex obtained by further copolymerizing acrylic acid or methacrylic acid with the copolymer latex. The photosensitive resin printing original plate for relief printing according to claim 1 or 2, wherein the high molecular compound (A) is a polyamide resin composed of polyamide and / or polyamide block copolymer and / or a partially saponified polyvinyl acetate resin.

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