JP2005331811A - Photosensitive resin composition,original printing plate using the same and the printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive resin composition superior in water developability and image reproducibility and free of flocculation of photosensitive resin components in a developer, and to provide a original printing plate which 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 ethylenically unsaturated compound comprises an ethylenically unsaturated compound (B) having a structure represented by Formula (1), wherein X is selected from H and methyl; and Y and Z are each independently selected from H, alkyl and alkylene. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

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

  Such a printing plate precursor is formed by adhering a negative and positive original image film to a photosensitive layer and irradiating actinic rays through the original image film to form a part that dissolves in a solvent and a part that does not dissolve in the photosensitive layer. A relief image is formed and used as a printing plate.

  The photosensitive resin composition used for such a printing plate material is generally composed of a polymer, an ethylenically unsaturated compound, and a photopolymerization initiator, and the currently used printing plate is generally one that can be developed with water. Is.

  However, since many polymers, ethylenically unsaturated compounds, and the like used in the photosensitive resin composition originally have almost no solubility in water, the time required for water development is long. In addition, since the operation of removing the unexposed portion of the printing plate material by rubbing the surface of the printing plate material immersed in water with a brush during water development, as the time required for water development increases, There is a problem that a fine halftone dot portion, a thin line, an independent line, or the like is missing and image reproducibility is lowered. Furthermore, the photosensitive resin component once dissolved or dispersed in the developer may agglomerate due to an increase in the developer temperature or the like, and may adhere to the brush, resulting in a problem that the developability is lowered.

From such a background, for the purpose of improving the dispersion and solubility of the polymer in water, a photosensitive resin printing plate material containing a partially saponified polyvinyl acetate derivative as a polymer component (for example, see Patent Document 1), Photosensitive resin printing plate material containing piperazine-based polyamide (for example, see Patent Document 2) and photosensitive resin printing plate material containing polyamide having a polyether segment in the molecular chain (for example, see Patent Document 3). Etc. have been proposed. In addition, a water-developable photosensitive resin composition containing a surfactant (for example, see Patent Document 4) and the like has been proposed in order to improve water developability. However, the development time is shortened and further image reproducibility is improved. Improvements and prevention of aggregation of resin components when the developer temperature rises are desired.
Japanese Patent Publication No. 63-48327 Japanese Patent Publication No.54-22229 Japanese Patent Publication No.59-50051 JP-A-10-171111

  An object of the present invention is to propose a photosensitive resin composition which is excellent in water developability and image reproducibility and does not aggregate the photosensitive resin component in the developer, and a printing plate precursor 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 an ethylenically unsaturated compound (B) Is a photosensitive resin composition comprising an ethylenically unsaturated compound (b) having a structure represented by the following general formula (1).

(In the formula, X is selected from hydrogen or a methyl group, and Y and Z are each independently selected from hydrogen, an alkyl group, and an alkylene group)

  According to the photosensitive resin composition of the present invention, it is possible to obtain a printing plate material having a short development time and excellent image reproducibility, particularly independent point and fine line reproducibility. Further, there is an effect of suppressing aggregation of the photosensitive resin component in the developer.

  Embodiments of the present invention will be described below.

  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 the water-soluble or water-swellable polymer include partially saponified polyvinyl acetate, polyvinyl alcohol, polyamide having a polyoxyalkylene segment or an alicyclic diamine segment in the polymer main chain, and the like. Water-soluble or water-swellable polymers can also be used.

  In the present invention, a water-soluble or water-swellable polyamide is preferably used from the viewpoints of water developability, printing durability, flexibility, toughness and the like. Among these, a polyamide having a polyoxyethylene (or polyoxypropylene) copolymer segment or a piperazine segment in the polymer chain is preferably used.

  Specific examples of the polyamide having a polyoxyethylene copolymer segment in the main chain include (a) polyoxyethylenediamine or polyoxyethylenedicarboxylic acid, and (a) for example, oxalic acid, succinic acid, glutaric acid, adipic acid, Pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, aliphatic dicarboxylic acid such as diglycolic acid, or ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, undecamethylenediamine, Examples thereof include copolymer polyamides containing units derived from aliphatic diamines such as dodecamethylenediamine, 2,2,4- and 2,4,4-trimethylhexamethylenediamine as main constituent units.

  The number average molecular weight of the polyoxyethylene segment portion of polyoxyethylenediamine or polyoxyethylenedicarboxylic acid is preferably 180 to 2500. Moreover, it is preferable that the structural unit which consists of said (a) and (a) contained in copolyamide exists in the range of 10 to 70 weight%.

  Specific examples of polyamides having an alicyclic diamine segment in the main chain include (c) alicyclic diamines such as 2-aminoethylpiperazine and (d) e.g. oxalic acid, succinic acid, glutaric acid. , A copolymerized polyamide containing a unit derived from an aliphatic dicarboxylic acid such as adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, diglycolic acid as a main constituent unit It is done.

  Moreover, it is preferable that the structural unit which consists of said (c) and (d) contained in copolyamide exists in the range of 10 to 90 weight%.

  The amide group-forming copolymerization component to be copolymerized with the polyoxyalkylene segment or the alicyclic diamine segment is not particularly limited, and known components can be used. For example, a combination of lactam such as ε-caprolactam, ω-laurolactam, 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, amino acid and the above-mentioned aliphatic, alicyclic or aromatic diamine, dicarboxylic acid The component chosen from the salt etc. which are derived from can be used.

  Furthermore, the water-soluble or water-swellable polymer and other polymers can be mixed and used. Polymers to be mixed include 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, Examples of chlorinated polyethylene, polyvinyl chloride, partially saponified polyvinyl acetate, and copolymers thereof are those usually used in photosensitive resin compositions.

  The content of the water-soluble or water-swellable polymer (A) in the present invention is preferably 10 to 80% by weight, more preferably 30 to 70% by weight in the photosensitive resin composition. When the content is 10% by weight or more, the toughness of the printing plate becomes good, and when it is 80% by weight or less, the developability becomes good.

  The ethylenically unsaturated compound (B) of the present invention contains an ethylenically unsaturated compound (b) having a structure represented by the following general formula (1). By including such an ethylenically unsaturated compound, the compatibility with the polymer is good, and the effects of the present invention such as developability and prevention of aggregation of the developer can be obtained.

(In the formula, X is selected from hydrogen or a methyl group, and Y and Z are each independently selected from hydrogen, an alkyl group, and an alkylene group)
Among these substituents, an alkyl group is one having 5 or less carbon atoms, and hydrogen in the alkyl group may be substituted with oxygen, nitrogen, or a halogen atom such as chlorine or bromine. The alkylene group is a group having 5 or less carbon atoms, and the alkylene group may have an ether bond. A ring may be formed between the substituents X and Y.

  Specific examples of the ethylenically unsaturated compound (b) having the structure represented by the general formula (1) include N, N-dimethylaminopropyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, (meta ) Acryloylmorpholine, N-isopropyl (meth) acrylamide, N, N-diethyl (meth) acrylamide and the like, but are not limited thereto.

  The ethylenically unsaturated compound (B) of the present invention can contain a known ethylenically unsaturated compound in addition to the ethylenically unsaturated compound (b). 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 Compounds having only one ethylenically unsaturated bond, such as aminoethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, and diethylene glycol di (meth) acrylate Poly (ethylene glycol) di (meth) acrylate, polypropylene glycol di (meth) acrylate such as dipropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra ( Ethylenically unsaturated bonds such as unsaturated carboxylic acids and unsaturated alcohols and active hydrogen to meth) acrylate, glycerol tri (meth) acrylate, ethylene glycol diglycidyl ether The polyvalent (meth) acrylate obtained by the addition reaction of a compound having an unsaturated epoxy compound such as glycidyl (meth) acrylate with a compound having an active hydrogen such as carboxylic acid or amine And compounds having two or more ethylenically unsaturated bonds, such as poly (meth) acrylamides such as (meth) acrylate and methylenebis (meth) acrylamide, polyvalent vinyl compounds such as divinylbenzene, and the like.

  The content of the ethylenically unsaturated compound (b) having the structure represented by the general formula (1) is preferably 5 to 70% by weight, more preferably 20 to 60% by weight in the ethylenically unsaturated compound (B). %. When the content is 5% by weight or more, a sufficient effect of improving developability is obtained. When the content is 70% by weight or less, the image reproducibility and the thermal stability of the photosensitive resin composition are improved.

  The content of the ethylenically unsaturated compound (B) in the present invention is preferably 10 to 80% by weight, more preferably 30 to 70% by weight in the photosensitive resin composition. When the content is 10% by weight or more, the effect of shortening the development time is great, and when it is 80% by weight or less, the printing durability of the printing plate 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. If it has the function to start, it will not specifically limit, A well-known photoinitiator can be used. Examples include acetophenones, benzoin ethers, benzophenones, thioxanthones, anthraquinones, benzyls, biacetyls and the like.

  Examples of the photopolymerization initiator preferably used in the present invention include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone and the like.

  The content of the photopolymerization initiator (C) in the present invention is preferably 0.3 to 5% by weight, more preferably 0.5 to 3% by weight in the photosensitive resin composition. When the content is 0.3% by weight or more, the photopolymerization reaction of the ethylenically unsaturated compound is sufficiently caused by actinic rays, and when the content is 5% by weight or less, a sufficient drawing depth can be ensured.

  It is preferable to add a surfactant to the photosensitive resin composition of the present invention from the viewpoints 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 polyoxyethylenes, anionic surfactants such as sulfonates, sulfates and phosphates, cationic surfactants such as amines, amphoteric surfactants, etc. Can be illustrated.

  Among the surfactants used in the present invention, anionic surfactants are preferably used. Specifically, aliphatic carboxylates such as sodium laurate and sodium oleate, sodium lauryl sulfate, sodium cetyl sulfate, Higher alcohol sulfates such as sodium oleyl sulfate, polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene octylphenyl ether sulfate, sodium polyoxyethylene nonylphenyl ether sulfate Such as polyoxyethylene alkyl allyl ether sulfate, alkyl diphenyl ether disulfonate, sodium dodecyl sulfonate, etc. Sulfonates, alkyl disulfonates, alkyl allyl sulfonates such as sodium dodecylbenzene sulfonate, sodium dibutyl naphthalene sulfonate, sodium triisopropyl naphthalene sulfonate, disodium lauryl phosphate, sodium lauryl phosphate Polyoxyethylene alkyl ether phosphate salts such as higher alcohol phosphate ester salts, polyoxyethylene lauryl ether phosphate monoester disodium, polyoxyethylene lauryl ether phosphate diester sodium, and the like are used in combination. It is also possible. In addition, although the sodium salt was mentioned as a specific example, it is not specifically limited to a sodium salt, The same effect can be acquired also with calcium salt, ammonia salt, etc.

  Among the surfactants used in the present invention, those containing a sulfonate are preferable, and specific examples include alkyl diphenyl ether disulfonate, naphthalene sulfonic acid formalin condensate, etc. It is preferably used from the viewpoint of preventing aggregation of the photosensitive resin component in the liquid and further from the viewpoint of image reproducibility.

  The content of the surfactant in the present invention is preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight in the photosensitive resin composition. Within this range, both image reproducibility and the effect of shortening the development time can be achieved.

  A plasticizer can be added to the photosensitive resin composition of the present invention for the purpose of imparting flexibility. 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, polyethylene glycol is preferably used from the viewpoints of flexibility and toughness.

  The addition amount of the plasticizer in the present invention is preferably in the range of 1 to 20% by weight, more preferably 3 to 15% by weight. Within this range, both image reproducibility and plasticizing effect can be achieved.

  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, hydroquinones, catechols and the like.

  The addition amount of the polymerization inhibitor in the present invention is preferably in the range of 0.1% by weight or less. If it is 0.1 weight% or less, the ultraviolet curing of the photosensitive resin composition will not be affected.

  For the purpose of improving various properties, the photosensitive resin composition of the present invention further includes an antifoaming agent, an ultraviolet absorber, an oxygen scavenger, a colorant (dye, pigment, photochromic agent, coloring aid), a fragrance, and the like. Can be added.

  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. In this way, a photosensitive resin composition solution is obtained. A photosensitive resin printing plate precursor can be obtained by casting this solution onto a substrate 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 sandwiching the photosensitive resin sheet between the substrate and the cover film. As the substrate, a metal such as steel, stainless steel or aluminum, a plastic sheet such as polyester, or a synthetic rubber sheet such as styrene-butadiene rubber is used.

  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 layer from which the cover film has been peeled, and a wavelength of usually 300 to 400 nm is used. UV irradiation with a high-pressure mercury lamp, ultra-high pressure mercury lamp, metal halide lamp, xenon lamp, carbon arc lamp, chemical lamp, etc. that can be irradiated with UV light, and curing by photopolymerization. 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. The liquid temperature during development is preferably 15 ° C to 30 ° 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.

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

(Synthesis Example 1: Synthesis of water-swellable polyamide)
60 parts by weight of an 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 this with hydrogen, 20 parts by weight of ε-caprolactam 20 parts by weight of an equimolar salt of hexamethylenediamine and adipic acid was melt polymerized under normal conditions to obtain a polyamide having a relative viscosity (1 g of polymer dissolved in 100 ml of chloral hydrate and measured at 25 ° C.) of 2.50. Obtained.

(Synthesis Example 2: Synthesis of water-soluble polyamide)
90 parts by weight of an equimolar salt of 2-aminoethylpiperazine and adipic acid and 10 parts by weight of ε-caprolactam were melt-polymerized under normal conditions, and the relative viscosity (1 g of polymer was dissolved in 100 ml of chloral hydrate and measured at 25 ° C. ) Gave a polyamide of 2.40.

(Synthesis Example 3: Synthesis of tetrafunctional acrylate)
In the presence of the polymerization inhibitor phenothiazine, at 50 ° C. in ethanol, 1 mol of xylenediamine was gradually added to 4 mol of glycidyl methacrylate over 4 hours to react. The reaction proceeded quantitatively to obtain a tetrafunctional acrylate having a solid concentration of 80% by weight.

(Characteristic evaluation of printing plate precursor)
Vacuum adhesion of gray scale negative film for sensitivity measurement and negative film for image reproducibility evaluation (with 3% halftone dot of 175 line, 150 μm independent point, 50 μm fine line, 300 μm wide outline) to the photosensitive resin printing plate precursor Then, the exposure was performed with a chemical lamp under the conditions of gray scale sensitivity of 16 ± 0.5.

After exposure, developed with a brush-type developing device with a developer temperature of 25 ° C., dried at 60 ° C. for 10 minutes, and then post-exposed under the same conditions with a gray scale sensitivity of 16 ± 0.5 using a chemical lamp for evaluation. A printed version was obtained. This was evaluated by the following method.
Gray scale sensitivity: After preparing a printing plate for evaluation, the number of steps remaining without washing out the photosensitive resin was read.
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.
Shore D hardness: The Shore D hardness of the photosensitive resin composition after post-exposure was measured according to JIS K6253.
The 175 line 3% halftone dot: The periphery of the halftone dot portion of 1 × 1 cm was observed, and the superiority or inferiority was judged based on the presence or absence of the halftone dot.
150 μm independent points: Three 150 μm independent points were observed, and superiority or inferiority was judged based on the ratio of independent points being reproduced.
50 μ fine line: A 50 μm wide thin line having a length of 1 cm was observed, and the superiority or inferiority was determined by the presence or absence of bending.
300 μ width drawing depth: The drawing depth at 300 μ width was measured with an magnifying projector.
Aggregation property: Development was performed with neutral water at 25 ° C. to prepare a developer in which 5% by weight of the photosensitive resin composition was dissolved. This was heated while stirring in a 50 cc flask, and the temperature at which aggregation of the photosensitive resin component occurred was confirmed.

Example 1
A water-soluble or water-swellable polymer shown in Table 1 and a plasticizer were dissolved in a mixed solvent having a water / ethanol ratio of 45/55 (weight ratio) according to the addition amount shown in Table 2 at 85 ° C. for 2 hours. Subsequently, this solution was cooled to 65 ° C., and various ethylenically unsaturated compounds, photopolymerization initiators, surfactants, thermal polymerization inhibitors, fragrances, and color formers shown in Table 1 were added according to the addition amounts in Table 2, The mixture was mixed at 65 ° C. for 1 hour, and allowed to stand and degas for 1 hour at 65 ° C. to obtain a photosensitive resin composition solution. At this time, it prepared so that the solid content concentration of the photosensitive resin composition solution might be 55 weight%.

  The obtained photosensitive resin composition solution was cast on a 0.25 mm thick polyester film coated with an adhesive and then dried at 60 ° C. for 2 hours. A mixed solvent of water / ethanol = 50/50 (weight ratio) is applied onto the photosensitive layer thus obtained, and a cover film having an anti-adhesion layer is pressure-bonded onto a matted 100 μm polyester film. A cover film was attached to obtain a photosensitive resin printing plate precursor.

  Table 3 shows the results of evaluating the characteristics of the obtained photosensitive resin printing plate precursor. The development time was short and the reproducibility of halftone dots and independent points was good. Further, even when the developer was heated to 50 ° C., aggregation of the resin component did not occur.

Examples 2-6, Comparative Examples 1-2
According to the composition shown in Table 1 and Table 2, a photosensitive resin printing plate precursor was obtained in the same manner as in Example 1. However, when the water-swellable polyamide of Synthesis Example 1 was used as the component (A), the solid content concentration in the photosensitive resin composition solution was 70%.

  Table 3 shows the results of evaluating the characteristics of the obtained photosensitive resin printing plate precursor. In each of Examples 2 to 6, the development time was short, and the reproducibility of halftone dots and independent points was good. Further, even when a water-swellable polyamide that is relatively easy to aggregate is used, the developer aggregation temperature can be kept high.

  On the other hand, Comparative Examples 1 and 2 that do not contain the ethylenically unsaturated compound (b) having the structure represented by the general formula (1) have a long development time, and as a result, reproducibility of halftone dots, thin lines, or independent points. Decrease was observed. In Comparative Example 1 using water-swellable polyamide, developer aggregation was observed at 40 ° C.

Claims (5)

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 ethylenically unsaturated compound (B) is A photosensitive resin composition comprising an ethylenically unsaturated compound (b) having a structure represented by the formula (1).

(In the formula, X is selected from hydrogen or a methyl group, and Y and Z are each independently selected from hydrogen, an alkyl group, and an alkylene group) The photosensitive resin composition according to claim 1, further comprising a sulfonate surfactant. 3. The photosensitive resin composition according to claim 1, wherein the water-soluble or water-swellable polymer (A) is a polyamide having a polyoxyalkylene segment or an alicyclic diamine segment in the polymer main chain. . A printing plate precursor using the photosensitive resin composition according to claim 1. A printing plate using the printing plate precursor according to claim 4.