JP2681537B2 - Photosensitive resin composition - Google Patents

Description

The present invention relates to a photosensitive resin composition, and more specifically,
The present invention relates to a photosensitive resin composition suitable for a flexographic printing plate that is highly flexible and can be developed with an aqueous solution.

[Prior Art] A dry resin composition whose basic composition comprises a binder, a photopolymerizable unsaturated compound and a photopolymerization initiator is widely used as a material suitable for forming a relief image, and is used in flexographic printing. The version is also provided as one of them.

Incidentally, conventional photosensitive resin compositions for flexographic printing plates include, for example, U.S. Pat.Nos. 2,948,611, 3,024,180, JP-B-51-43374 and JP-B-43374.
As described in JP-A-59-22222, a chlorinated rubber, a styrene-butadiene block copolymer, an elastomer such as polyurethane is used as a binder, and a photopolymerizable unsaturated compound and a photopolymerization initiator are added to the binder. Made of added ones. However, such compositions require halogenated hydrocarbons in the developer for forming the image due to the large amount of binder used. Therefore, it has problems such as health problems and environmental pollution. On the other hand, various photosensitive resin compositions using a developing solution that does not require halogenated hydrocarbons are known other than those for flexographic printing plates. For example, JP-B-46-26125, JP-B-50-32645, JP-B-54-3790 and JP-B-57.
As described in, for example, JP-A-28485, water- or alcohol-soluble polyvinyl alcohol or polyamide is used as a binder, but the printing plate obtained by photocuring is hard, and for flexographic printing. Not suitable. Further, as described in JP-A-52-134655, JP-A-53-10648, JP-A-61-22339, JP-A-1-219735, JP-A-1-306836, etc. In, a conjugated diene hydrocarbon and α, β-ethylenically unsaturated carboxylic acid or a salt thereof as an essential component, a copolymerizable unsaturated monomer containing a monoolefin unsaturated compound therein,
There is a photosensitive resin composition that can be developed with an aqueous developer containing a photosensitizer. However, a printing plate obtained from such a composition is difficult to develop with household water having a pH of 5.0 to 9.0, and the ink resistance of the relief portion is insufficient,
Further, there is a problem that ozone resistance, weather resistance and oxidation resistance are insufficient.

Further, in JP-A-62-260142, (a) a water-soluble saturated polyester having an alkali metal salt type sulfonic acid group, (b) a photopolymerizable unsaturated compound and (c) a photopolymerization initiator are essential. Although a photosensitive resin composition characterized by containing as a component is disclosed, although the printing plate obtained with this composition has resistance to oil-based ink, a polar solvent such as aqueous or alcoholic is used. It is not practical because it has a drawback that it does not have resistance to the ink contained.

[Problems to be Solved by the Invention] Since the present invention can be applied to a flexographic printing plate capable of being water-developed, it overcomes the above-mentioned drawbacks of the conventional photosensitive resin composition and can be developed with household water. The purpose of the present invention is to provide a photosensitive resin composition suitable for a flexographic printing plate that can satisfy ink resistance.

[Means for Solving the Problems] The inventors of the present invention have conducted earnest studies to develop a photosensitive resin composition which is water-developable, rich in ink resistance, and developable with household water. As a result, it was found that a photosensitive resin composition using an alkali metal salt type water-soluble saturated polyester having a sulfonic acid group achieves the object, and based on this finding, the present invention has been completed.

That is, the present invention provides (a) a water-soluble saturated polyester having an alkali metal salt type sulfonic acid group, (b) an elastomer having rubber elasticity at around room temperature, (c) a photopolymerizable unsaturated compound, and (d) a photopolymerization. A photosensitive resin composition comprising an initiator is provided.

 Hereinafter, the present invention will be described in detail.

The water-soluble saturated polyester having an alkali metal salt type sulfonic acid group used in the composition of the present invention is an acid component monomer and an alcohol component monomer which are used as a raw material monomer of a normal saturated polyester. And an alkali metal salt type sulfonic acid group and a monomer having two or more ester-forming functional groups.

Examples of the acid component monomer include polyvalent carboxylic acids having two or more carboxyl groups, such as aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid and naphthalenedicarboxylic acid, trimellitic acid, pyromellitic acid and the like. Examples thereof include aromatic dicarboxylic acids such as aromatic polycarboxylic acids, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid.

As the monomer of the alcohol component, a polyhydric alcohol having two or more hydroxyl groups, such as ethylene glycol, propylene glycol, 1,3-propanediol,
1,4-butanediol, 1,5-pentanediol, 1,6-
Hexanediol, glycol such as 1,4-cyclohexanedimethanol, polyethylene glycol such as diethylene glycol and triethylene glycol, polypropylene glycol, or trimethylolpropane,
Pentaerythritol or the like is used.

As the monomer of the polyester, a hydroxycarboxylic acid component such as p-hydroxybenzoic acid, salicylic acid, 2-hydroxy-6-naphthoic acid, 2
Aromatic hydroxycarboxylic acids such as -hydroxy-3-naphthoic acid and aliphatic cyclic esters such as γ-butyrolactone and ε-caprolactone can also be used.

As the monomer having an alkali metal salt type sulfonic acid group and two or more ester-forming functional groups, the above-mentioned acid component monomer, alcohol component monomer or hydroxycarboxylic acid component monomer is an alkali metal salt. A sulfonic acid group-containing sulfonic acid group is used, but an aromatic dicarboxylic acid having an alkali metal salt-type sulfonic acid group introduced therein is preferable from the viewpoints of easy availability and physical properties of the resulting polyester. Examples of such a compound include 2-sodium or potassium sulfoterephthalic acid, 5-sodium or potassium sulfoisophthalic acid, and the like.

It is desirable that the monomer having an alkali metal salt type sulfonic acid group is used in an amount of 5 to 20 mol%, preferably 8 to 13 mol% in the polyester used. A polyester having a content of less than 5 mol% is inferior in stability when made into an aqueous solution or water-soluble. On the other hand, when it exceeds 20 mol%, the melt viscosity of the polyester becomes extremely high, and thus it is difficult to obtain a polyester having sufficient cohesive force in the polymerization.

In the water-soluble saturated polyester used in the present invention, as an acid component and optionally a hydroxycarboxylic acid, 10 to 85 mol% of an aromatic dicarboxylic acid or an aromatic hydroxycarboxylic acid-based aromatic component, an aliphatic dicarboxylic acid are used. It is preferable to use an aliphatic component such as an acid or an aliphatic hydroxycarboxylic acid in a proportion of 90 to 15 mol%. Furthermore, the aromatic dicarboxylic acid component is composed of terephthalic acid and isophthalic acid, the molar ratio of which is
Those in the range of 8: 2 to 5: 5, and the aliphatic dicarboxylic acid component and the aliphatic hydroxycarboxylic acid component include adipic acid, azelaic acid, sebacic acid, and ε-caprolactone having 2 to 10 methylene groups. Are preferred.

If the aromatic component is less than 10 mol%, the flexibility of the polyester becomes too large, and the resulting printing plate easily loses its shape. On the other hand, if it exceeds 85 mol%, the flexibility of the polyester becomes too small, which is obtained. It is not preferable because the flexibility of the printing plate tends to decrease. When an aliphatic dicarboxylic acid component or an aliphatic hydroxycarboxylic acid component having a methylene group number of more than 10 is used, the resulting polyester becomes water-soluble or lacks stability when made into an aqueous solution, which is not preferable. .

On the other hand, as the alcohol component, glycols such as ethylene glycol, 1,3-propanediol and 1,4-butanediol having no ether group having 2 to 8 carbon atoms are preferable. Glycols having 9 or more carbon atoms and not having an ether group are not preferred because they lack the water solubility of the polyester and the stability when made into an aqueous solution. Polyethylene glycol such as diethylene glycol and triethylene glycol and polypropylene glycol can also be advantageously used, but in this case, those having a molecular weight of 500 or less are preferable, and these are 40% by weight or less based on the produced polyester, particularly in the case of diethylene glycol. 35% by weight or less,
20% by weight for polyethylene glycol with a molecular weight of 500
It is preferable to use it in the following range. If the amount used exceeds 40% by weight or if the molecular weight is more than 500, the resulting printing plate is likely to lose its shape, which is not preferable.

The water-soluble saturated polyester used in the present invention may contain a copolymerization component other than the above components within a range not impairing the object of the present invention. The method for producing this product is not particularly limited, and any method can be used among the methods commonly used for producing polyesters. For example, a method in which dimethyl ester of dicarboxylic acid and glycol are heated in the presence of a catalyst for transesterification reaction, and then, in the presence of a catalyst, glycol is distilled off under reduced pressure while heating, or polycondensation, or dicarboxylic acid and glycol Can be produced by heating under pressure to cause an esterification reaction, and then polycondensation by distilling glycol off under reduced pressure while heating in the presence of a catalyst. At this time, it is preferable to add a color preventive agent, a heat stabilizer, etc., and to select polymerization conditions at a low temperature and a short time within a possible range.

The water-soluble saturated ester used in the present invention preferably has an intrinsic viscosity in the range of 0.28 to 0.65 measured at a temperature of 20 ° C. in a phenol / tetrachloroethane mixed solvent (weight ratio 1: 1). When the intrinsic viscosity is less than 0.28, the cohesive force of the polyester is insufficient, and when it exceeds 0.65, the elution rate at the time of producing the printing plate becomes small, which is not preferable.

The elastomer as the component (B) of the present invention has rubber elasticity at around room temperature, has a large elongation, has a large durability under a repeated load, and has a good abrasion resistance and an electrical insulating property. However, any one can be used as long as it has good compatibility with the above-mentioned component (a). Preferable examples thereof include butadiene rubber, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, ethylene-vinyl acetate copolymer and polyurethane. The preferable mixing ratio of the component (b) is (a)
5 to 200 parts by weight, preferably 10 to 100 parts by weight of the components
150 parts by weight. If the amount is less than 5 parts by weight, not only the resistance to the water-based ink after photocuring deteriorates, but also the flexibility and elasticity cannot be obtained. On the other hand, if the amount exceeds 200 parts by weight, it cannot be developed with an aqueous developer, which is not preferable.

Examples of the photopolymerizable unsaturated compound as the component (c) of the present invention include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, glycidyl acrylate, glycidyl methacrylate, benzyl acrylate, tribromophenyl acrylate, cyclohexyl acrylate, 2- Hydroxyethyl acrylate, 2
-Hydroxypropyl acrylate, acrylamide,
Methacrylamide, N-methylolacrylamide, N
-Ethyl acrylamide, N-Propyrrole acrylamide, N-Methylol methacrylamide, N-Ethyl methacrylamide, N-Propyrrole methacrylamide, n-butoxymethyl acrylamide, iso-butoxymethyl acrylamide, N-tert-butyl acrylamide, A photopolymerizable unsaturated compound having one unsaturated double bond such as sodium acrylate, ammonium acrylate, acrylonitrile, styrene, sodium styrenesulfonate, vinylpyridine, or allyl methacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1, 3-propanediol diacrylate, 1,4-butanediol diacrylate, 1,3-propanediol methacrylate, 1,4-
Butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane triacrylate,
Unsaturated double bonds such as tetramethylolmethane triacrylate, triacryloyloxyethyl phosphate, methylenebisacrylamide, ethylenebisacrylamide, propylenebisacrylamide, hexamethylenebisacrylamide, methylenebismethacrylamide, ethylenebismethacrylamide, propylenebismethacrylamide A photopolymerizable unsaturated compound having two or more is mentioned. These photopolymerizable unsaturated compounds may be used alone or in combination of two or more. The mixing ratio of this (C) ingredient is 100 (A) ingredient.
The amount is 5 to 200 parts by weight, preferably 10 to 150 parts by weight. If it is less than 5 parts by weight, the photocrosslinking density of the ultraviolet irradiation part is low and the irradiation time becomes long, and the mechanical strength is insufficient. On the other hand, if it exceeds 200 parts by weight, the shape retention of the image will be poor, and the plate after irradiation will be hard and brittle, so it is not suitable as a plate material for flexographic printing.

Examples of the photopolymerization initiator of the component (d) used in the composition of the present invention include benzophenones, benzoins, acetophenones, benzyls, benzoin alkyl ethers, benzyl alkyl ketals, anthraquinones, thioxanthones and the like. As specific examples of these, benzophenone, chlorobenzophenone, benzoin, acetophenone, benzyl, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl methyl ketal, benzyl ethyl ketal, benzyl diisopropyl ketal, Anthraquinone, 2-chloroanthraquinone, thioxanthone, 2-
For example, chlorothioxanthone. The mixing ratio of the component (d) is 0.01 to 5 parts by weight, preferably 0.1 to 5 parts by weight based on 100 parts by weight of the total of the components (i), (b) and (c).
3 parts by weight.

In the composition of the present invention, if necessary, a thermal polymerization inhibitor, for example, hydroquinone, methylhydroquinone, hydroquinone derivative such as hydroquinone monomethyl ether, phenol derivative such as 2,6-di-tert-butyl-p-cresol, p- Quinone derivatives such as benzoquinone and nitrobenzene and its derivatives can be added. The amount of these thermal polymerization inhibitors used is (a) component,
0.0 based on 100 parts by weight of the total of components (b) and (c)
It is selected in the range of 01 to 2 parts by weight, preferably 0.05 to 0.5 parts by weight.

In addition to the above, the photosensitive resin composition of the present invention contains liquid polybutadiene rubber as a plasticizer, liquid polyacrylonitrile butadiene rubber, liquid polystyrene butadiene rubber, liquid rubber such as liquid isoprene rubber, polyvinyl chloride, chlorinated polyethylene, and chlorine. A relatively low molecular weight elastomer such as modified polypropylene, trimethylolpropane, silica, fine powder such as diatomaceous earth, and the like can be contained.

Next, one example of a preferred method of using the composition of the present invention is as follows: (a) component, (b) component, (c) component, (d)
Ingredients and additives to be added if necessary, a suitable solvent,
For example, the photosensitive resin film can be formed by dissolving in tetrahydrofuran, dioxane, chloroform, methyl ethyl ketone, toluene, cyclohexane or the like, applying the solution on the substrate and drying and removing the solvent.

As another method, the component (a) and the component (b) may be dissolved under heating, and then the component (c) and the component (d) may be dissolved in the components and the solution may be applied onto the substrate. As the substrate at this time, a metal plate such as steel, stainless steel, aluminum or copper, a plastic sheet such as polyester, a synthetic rubber sheet or the like is used, and an adhesive layer may be provided in advance on the surface of these substrates.

The thickness of the photosensitive resin film thus obtained is 0.1
It is preferable that it is -10 mm as a printing plate. Next, attach the required original mask onto the photosensitive resin coating,
Ultra high pressure mercury lamps, metal halide lamps, xenon lamps, chemical lamps, carbon arc lamps, etc., that emit ultraviolet rays of ~ 450 μm, irradiate the photosensitive resin film with ultraviolet rays through an original mask, and photopolymerize the irradiated areas to develop the developer. Then, the non-irradiated portion is dissolved and removed by a developing solution to form an image faithful to the original mask, and the printing plate material is obtained.

EXAMPLES Next, the present invention will be described in more detail by showing examples, but the present invention is not limited to these examples.

Reference Example 1 Production of water-soluble saturated polyester 0.30 mol of ethylene glycol terephthalate,
Isophthalic acid 0.25 mol, sebacic acid 0.33 mol, 5-sodium sulfoisophthalic acid ethylene glycol ester
0.12 mol, ethylene glycol, 0.76 mol, 60 mg of antimony trioxide and 200 mg of sodium acetate trihydrate were placed in a polymerization test tube and stirred at 160-220 ° C under a nitrogen atmosphere while stirring.
The mixture was heated to the temperature to carry out the esterification reaction. Distillation of water was completed in about 2 hours, and the reaction was allowed to proceed for another 1 hour. Then the temperature
The temperature was raised to 270 ° C., and the pressure in the reaction system was gradually reduced to 13 Pa or less in about 1 hour, and the polycondensation reaction was further performed for 1 hour.
The obtained polyester was colorless and transparent and had elasticity, and its intrinsic viscosity was 0.50.

Example 1 100 parts by weight of the water-soluble saturated polyester obtained in Reference Example 1 Block copolymer of styrene / isoprene (Califlex TR 1107 manufactured by Shell Co., Ltd.) 100 parts by weight 20 parts by weight of trimethylolpropane triacrylate hexanedioldi Acrylate 10 parts by weight Benzyl dimethyl ketal (IR 651 manufactured by Ciba-Geigy Co., Ltd.) 2 parts by weight 2,6-di-tert-butyl-p-cresol 0.05 parts by weight Toluene 200 parts by weight A mixture having the above composition is placed in a flask at 60 ° C. While heating, the solution was uniformly dissolved while stirring to prepare a photosensitive resin composition. The composition thus obtained was cast on a 125 μm polyethylene terephthalate film provided with an antihalation layer so as to have a constant film thickness, and at 50 ° C.
A photosensitive layer having a film thickness of 1 mm was obtained by drying for 20 hours.
A test negative mask is vacuum-bonded onto this photosensitive layer 2.
Chemical lamp from a distance of 4 cm (PL20BL manufactured by Toshiba Corp.)
Type) for 10 minutes, then wash the non-irradiated area for 6 minutes with warm water at 45 ° C using a brush-type washing machine,
It was dried at 60 ° C. for 20 minutes, and the entire surface was irradiated with ultraviolet rays by the chemical lamp for 5 minutes.

As a result, 85 lines / inch, 3% halftone dot highlight portion of the test negative mask was reproduced. Further, the hardness of the relief was Shore A 60 °, and a flexographic printing plate material having flexibility and elasticity was obtained.

When this plate material was put into a printing machine and printing was performed, a printed matter with good ink transfer and excellent reproducibility was obtained.

Example 2 100 parts by weight of the water-soluble saturated polyester obtained in Reference Example 1 120 parts by weight of a styrene-butadiene block copolymer (Califlex TR 1102 manufactured by Shell Co., Ltd.) 30 parts by weight of trimethylolpropane triacrylate Liquid rubber ( Idemitsu Petrochemical Co., Ltd. Poly bd R 45TH 50 parts by weight Benzyl dimethyl ketal (Ciba Geigy Co., Ltd. IR 651) 2 parts by weight 2,6-di-tert-butyl-p-cresol 1 part by weight A heating kneader The mixture was kneaded at 180 ° C. and defoamed to obtain a photosensitive resin composition. This with a heat press machine 150
The adhesive, polyvinyl alcohol is a photosensitive resin composition between a 125 μm thick polyethylene terephthalate film coated with an adhesive at a temperature of 100 ° C. and a pressure of 100 kg / cm ² and a polyethylene terephthalate film provided with a polyvinyl alcohol coating of 2 μm thick. The photosensitive resin composition was heated and pressed for 1 minute so as to be on the object side to prepare a photosensitive layer laminated sheet having a thickness of 2.97 mm. Next, the whole surface is irradiated with a chemical lamp for 4 minutes from the side of the polyethylene terephthalate film coated with the adhesive, and then the polyethylene terephthalate film provided with the polyvinyl alcohol coating is peeled off leaving the polyvinyl alcohol on the photosensitive layer and then on the photosensitive layer. Attach a negative mask for test under reduced pressure and use a chemical lamp.
Irradiated for 15 minutes. After removing the negative mask, use water at 30 ° C for 15
It was developed with a brush for 30 minutes and dried at 60 ° C. for 30 minutes.
As a result, an image pattern with a relief depth of 1.8 mm was obtained. This image pattern faithfully reproduced the negative mask. The hardness was Shore A50 °. When this was applied to a flexographic printing machine, ink acceptability was good and good printed matter was obtained.

Reference Examples 2 to 5 Water-soluble polyesters were synthesized in the same manner as in Reference Example 1. The composition is shown in Table 1.

Examples 3 to 5 Flexographic printing plate materials were prepared in the same manner as in Example 1 using the water-soluble saturated polyesters of Reference Examples 2 to 5, and their performances were investigated.

 Table 2 shows the results.

[Effect of the Invention] The photosensitive resin composition of the present invention is solid at room temperature,
Further, since it has a property of becoming liquid when heated, it is possible to form a uniform photosensitive resin film without using a solvent, if necessary. Further, it can be developed with an aqueous solution and has resistance to various inks. Furthermore, since it is excellent in flexibility and elasticity and the image is extremely clear, it can be used as a high-grade printing plate.

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Claims (1)

(57) [Claims] 1. A water-soluble saturated polyester having an alkali metal salt type sulfonic acid group, (b) an elastomer having rubber elasticity at around room temperature, (c) a photopolymerizable unsaturated compound, and (d) initiation of photopolymerization. A photosensitive resin composition comprising an agent.