JP3716530B2 - Photosensitive resin composition for printing plate and photosensitive resin plate material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photosensitive resin composition for a printing plate, and more particularly to a photosensitive resin composition for a printing plate that is suitably used for flexographic printing with improved water developability.
[0002]
[Prior art]
A photosensitive resin composition in which an elastomer such as a chlorinated rubber, a styrene-butadiene block copolymer, and a polyurethane is used as a carrier resin component and an ethylenically unsaturated compound and a photopolymerization initiator are arranged in the elastomer, makes use of the characteristics of the elastomer. It is useful as a flexographic printing plate material, and many proposals have been made, such as US Pat. Nos. 2,948,611, 3,024,180, and Japanese Patent Publication No. 51-43374.
[0003]
Such photosensitive resin solid plate material requires halogenated hydrocarbon development, and has problems such as health problems and environmental pollution, so development of photosensitive resin solid flexographic printing plate material that can be developed with water For example, Japanese Patent Publication No. Sho 62-42259, Japanese Patent Laid-Open Publication No. 61-22339, Japanese Patent Laid-Open Publication No. 63-186232, etc., a photosensitive resin that provides a water-developable photosensitive resin solid flexographic printing plate material. Proposals for the composition have been made.
[0004]
However, it is difficult and practical to satisfy all of the printing plate strength and water developability, flexibility as a flexographic printing plate, and compatibility with water-based ink, which is the main ink of flexographic printing. Satisfaction is not obtained. In particular, in the development process, a photosensitive resin solid flexographic printing plate material having practical developability with substantially only neutral water has not been obtained.
[0005]
[Problems to be solved by the invention]
The present invention was devised in view of the shortcomings of the prior art, and its object is high image reproducibility, good water developability, and satisfactory compatibility with water-based inks. Another object of the present invention is to provide a photosensitive resin composition suitable for a printing plate.
[0006]
[Means for Solving the Problems]
The problem of the present invention is that
“(A) For a printing plate containing a compound having 3 or more hydroxyl groups, an amide bond and a hydrocarbon group having 6 or more carbon atoms in the molecule, (B) a polymerizable unsaturated compound and (C) a photopolymerization initiator” Photosensitive resin composition "
[The photosensitive resin composition for a printing plate, wherein the component (A) is an N-alkyl gluconamide compound represented by the general formula (I).
[Chemical formula 2]
R-HNCO (CHOH) _Four CH ₂ OH
(Wherein R is an alkyl group having 6 to 24 carbon atoms) "
“The photosensitive resin composition for a printing plate, comprising 0.01 to 20% by weight of the N-alkyl gluconamide compound”,
“The photosensitive resin composition for a printing plate according to any one of the above, further comprising a base resin”,
"The above-mentioned printing plate photosensitive resin composition, wherein the base resin contains a hydrophilic polymer and rubber."
The above-mentioned photosensitive resin composition for a printing plate in which a vulcanized rubber and an unvulcanized rubber are dispersed in a hydrophilic polymer. Furthermore, the present invention utilizes the property.
A photosensitive resin plate material obtained by coating the photosensitive resin composition for a printing plate according to any one of the above on a support. It consists of.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. In the present invention, “weight” means “mass”.
[0008]
The composition of the present invention preferably contains a base resin. It is particularly preferable to use a hydrophilic polymer as an essential component. In order to use as a flexographic printing plate, it is preferable to further contain a rubber component.
[0009]
The hydrophilic polymer of the present invention refers to a polymer having a property of being dissolved and / or dispersed in water. For example, a polymer formed into a film is immersed in water at 23 ° C., and the polymer is completely eluted after 24 hours. In addition, it means that the film is reduced or disintegrated by 50% by weight or more due to partial elution or when the polymer swells and disperses and disperses in water.
[0010]
Examples of such hydrophilic polymers include polymers that can be dissolved in alcohol and / or water, and polyamides, partially saponified polyvinyl acetate, celluloses, and the like can be used. From the viewpoint of compatibility with an unsaturated compound, it is preferable to mainly use polyamide.
[0011]
The present invention has been made to find a photosensitive resin composition that can be developed in neutral water by utilizing the properties unique to such a hydrophilic polymer, particularly hydrophilic polyamide, and can be applied to printing with aqueous ink.
[0012]
The hydrophilic polyamide used in the present invention includes all conventionally proposed polyamides. For example, polyamides containing sulfonic acid groups or sulfonate groups obtained by copolymerizing sodium 3,5-dicarboxybenzenesulfonate as disclosed in JP-A-48-72250, A polyamide having an ether bond obtained by copolymerizing any one of dicarboxylic acid having an ether bond in the molecule, diamine, or cyclic amide as disclosed in Japanese Patent No. 43465, Polyamides containing basic nitrogen obtained by copolymerizing N, N′-di (γ-aminopropyl) piperazine and the like as disclosed in JP-7605 and quaternary of these polyamides with acrylic acid or the like Polyamide having a molecular weight of 150 to 1500 proposed in JP-A-55-74537 Copolymerized polyamides containing tersegments and ring-opening polymerization of α- (N, N′-dialkylamino) -ε-caprolactam or α- (N, N′-dialkylamino) -ε-caprolactam and ε-caprolactam Examples thereof include polyamides obtained by ring-opening copolymerization.
[0013]
Among these hydrophilic polyamides, a copolymer polyamide containing a polyether segment having a molecular weight of 150 to 1500, more specifically a polyoxy having an amino group at the terminal and a molecular weight of the polyether segment part of 150 to 1500. Copolymer polyamides containing 30 to 70% by weight of structural units composed of ethylene and an aliphatic dicarboxylic acid or diamine are preferably used.
[0014]
These hydrophilic polyamides may be used alone or in combination of two or more.
[0015]
In order to use as a flexographic printing plate, it is preferable to further contain rubber as a base resin. The rubber of the present invention means unvulcanized rubber or vulcanized rubber or both. The vulcanized rubber is obtained by vulcanizing an unvulcanized rubber. However, the unvulcanized rubber is not particularly limited, and a so-called solid rubber having a molecular weight of 40,000 or more is preferably used. For example, raw rubber or elastomer such as high molecular weight isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, acrylic rubber, epichlorohydrin rubber, silicone rubber, styrene-butadiene copolymer, Examples include copolymers of dienes such as styrene-isoprene copolymer and butadiene-acrylic acid copolymer, and copolymers of olefins such as ethylene-propylene copolymer and ethylene-vinyl acetate copolymer. . Of these, copolymers of dienes or olefins are preferably used. As these unvulcanized rubbers, both self-vulcanizable and non-self-vulcanizable rubbers are suitable for the practice of the present invention. Non-self-vulcanizable rubbers require the presence of a vulcanizing agent to vulcanize the rubber to a degree where the rubber gel content is at least about 80% or higher at processing temperatures. Self-vulcanizing rubber, as its name implies, vulcanizes at processing temperatures to the extent that the gel content of the rubber is at least about 80% or more without a vulcanizing agent.
[0016]
In the present invention, the vulcanizing agent component of rubber is not particularly limited, and vulcanizing agents and vulcanizing agent systems usually used for diene rubber vulcanization can be used. Any vulcanizing agent and vulcanizing system applicable to the vulcanization of diene rubber, such as peroxide, azide, quinoid or accelerated sulfur vulcanizing system can be used in the practice of the present invention. A combination of maleimide and peroxide or disulfide accelerator can be used. A sufficient amount of vulcanizing agent is used to achieve essentially complete vulcanization of the rubber. Excessive vulcanizing agents should be avoided. The reason is that much higher amounts than are necessary to fully vulcanize the rubber result in poorer properties such as lowering the properties of the hydrophilic polymer dissolved and / or dispersed in water.
[0017]
In order to achieve both the water developability of the printing plate material and the compatibility of the printing plate with water-based ink, it is preferable that rubber is dispersed in these hydrophilic polymers. As a method for dispersing the rubber in the hydrophilic polymer, there is a method in which the hydrophilic polymer and the unvulcanized rubber are melt-mixed and then the unvulcanized rubber is optionally vulcanized. Melt mixing refers to mixing two or more polymers at a temperature above the softening point. By carrying out the melt mixing, the rubber particles having a small size are dispersed throughout the continuous hydrophilic polymer matrix, and the desired blend polymer can be obtained by vulcanizing the rubber particles thereafter. The blend polymer is produced by mixing the hydrophilic polymer with unvulcanized rubber and, if required, a vulcanizing agent and then subjecting the blend to normal mastication at a temperature sufficient to effect vulcanization formation. A device such as a Banbury mixer, a Brabender mixer or a biaxial mixing extruder is used for mastication. The hydrophilic polymer and rubber are mixed at a temperature sufficient to soften the hydrophilic polymer, or more generally at a temperature above its melting point if the hydrophilic polymer is crystalline at normal temperature. After the hydrophilic polymer and the rubber are intimately mixed, a vulcanizing agent is added as necessary. Heating and mastication at the vulcanization temperature is generally sufficient to complete the vulcanization formation in a few minutes or less. However, higher temperatures can be used if shorter times are desired. A suitable temperature range for the formation of vulcanization is from the melting temperature of the hydrophilic polymer to the decomposition temperature of the rubber, and this range is generally about 100 ° C to 250 ° C, but the maximum temperature is the type of rubber and the degradation inhibitor. It will vary somewhat depending on the presence and mixing time. Typically, this range is about 130 ° C to 250 ° C. A preferred range is from about 150 ° C to 230 ° C. In order to obtain a good rubber vulcanized blend polymer, it is important to continue until vulcanization occurs without stopping mixing.
[0018]
The mixing ratio of the hydrophilic polymer and the rubber is preferably 1 to 9 to 8 to 2, more preferably 1 to 9 to 5 to 5, by weight.
[0019]
It is preferable that the usage-amount of a hydrophilic polymer is 3 to 40 weight% in a total photosensitive resin composition, More preferably, it is 5 to 20 weight%. When the amount is less than 3% by weight, the developability is lowered and the shape retention of the green plate is lowered. When it is more than 40% by weight, the water resistance of the printing plate is lowered and the printing durability is deteriorated.
[0020]
The amount of rubber used is preferably 10 to 80% by weight, more preferably 30 to 70% by weight in the total photosensitive resin composition. This rubber includes not only a blend polymer rubber but also a rubber emulsion added during the preparation of the photosensitive resin composition, and fine particles of vulcanized rubber. When the amount is less than 10% by weight, the flexibility of the printing plate is lowered. When the amount is more than 80% by weight, the developability is lowered.
[0021]
Component (A), which is a feature of the present invention, has three or more hydroxyl groups, amide bonds, and hydrocarbon groups having 6 or more carbon atoms in the molecule. Further, the number of hydroxyl groups is preferably 5 or more. By having these functional groups, the compatibility between the hydrophilic polymer and other components, such as rubber, can be improved. Further, the rubber is contained in the hydrophilic polymer as particles having an average particle diameter of 0.001 to 10 μm. By dispersing, the water developability is remarkably improved.
[0022]
As the component (A), an N-alkyl gluconamide compound represented by the following formula can be preferably used.
[0023]
[Chemical 3]
R-HNCO (CHOH) _Four CH ₂ OH
(Wherein R is an alkyl group having 6 to 24 carbon atoms) "
In the N-alkyl gluconamide compound represented by the general formula of the present invention, R is a linear or branched alkyl group, and the alkyl group has 6 to 24 carbon atoms in the present invention. Is suitable for the purpose. If the carbon number of the alkyl group is smaller than 6, the moldability of the rubber-containing photosensitive resin composition tends to be lowered, and if it is larger, the property as a printing plate tends to be lost. It is better to select from the range.
[0024]
Examples of these N-alkyl gluconamides include N-hexyl gluconamide, N-heptyl gluconamide, N-octyl gluconamide, N-nonyl gluconamide, N-decyl gluconamide, N-undecyl gluconamide, N -Dodecyl gluconamide, N-tridecyl gluconamide, N-tetradecyl gluconamide, N-pentadecyl gluconamide, N-heptadecyl gluconamide, N-octadecyl gluconamide, N-nonadecyl glucoamide, N-eicosyl Gluconamide, N-henecosyl gluconamide, N-docosyl gluconamide, N-tricosyl gluconamide and the like can be mentioned.
[0025]
As the addition of the component (A) to these rubber-containing photosensitive resin compositions, one or two or more kinds can be appropriately selected and used. However, the amount used can be changed depending on the base resin used, for example, the type of rubber or hydrophilic polymer, or molding means, but is usually 0.01 to 20% by weight in the total photosensitive resin composition. It is preferable that it is 0.1 to 10% by weight.
[0026]
The component (A) of the present invention can be used in combination with a conventionally used lubricant or mold release agent.
[0027]
Further, the component (A) of the present invention may be used when kneaded with the base resin in advance, and at the time of preparing the rubber-containing photosensitive resin composition, a dye, a pigment, a surfactant, an antifoaming agent, an ultraviolet absorber, and a fragrance. It can also be kneaded and used with various additives such as.
[0028]
The total amount of the base resin is preferably 20 to 90% by weight, more preferably 50 to 80% by weight in the total photosensitive resin composition. When the amount is less than 20% by weight, the obtained plate surface has increased adhesion, and the plate form retainability is impaired. If it exceeds 90% by weight, the photosensitivity of the plate, particularly the image reproducibility is lowered.
[0029]
The polymerizable unsaturated compound (B) is added to the composition of the present invention. Specifically, the following are mentioned. 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro- Monoacrylates and monomethacrylates having a hydroxyl group such as 2-hydroxypropyl methacrylate. A polyvalent acrylate and a polyvalent methacrylate obtained by reacting a polyhydric alcohol such as ethylene glycol with an unsaturated carboxylic acid such as acrylic acid or methacrylic acid. Unsaturated epoxy compounds such as glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexyl acrylate, 3,4-epoxycyclohexyl methacrylate. Polyhydric acrylates and polyhydric methacrylates having hydroxyl groups synthesized by the reaction of polyvalent glycidyl ethers such as ethylene glycol diglycidyl ether and unsaturated carboxylic acids such as acrylic acid and methacrylic acid. A polyvalent acrylate and a polyvalent methacrylate having a hydroxyl group synthesized by a reaction of an unsaturated epoxy compound such as glycidyl methacrylate and an unsaturated carboxylic acid such as acrylic acid or methacrylic acid. Acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, diacetone acrylamide, methylenebisacrylamide, N-methylol acrylamide or N-methylol methacrylamide obtained by condensation reaction of polyhydric alcohol and polyvalent acrylamide Examples include acrylamide-based photopolymerizable monomers such as methacrylamide, and acrylic or methacrylic esters having a hydroxyl group and acrylic or methacrylamide are preferably used.
[0030]
The proportion of the component (B) in the photosensitive resin composition is preferably in the range of 10 to 80% by weight. More preferably, it is 10 to 60% by weight. When the proportion of the component (B) in the photosensitive resin composition is less than 10% by weight, the density of the cross-linked structure generated by photopolymerization is insufficient, so that the water based ink dilution solvent is used as a main component. It becomes easy to swell, and it becomes easy to produce the swelling destruction of a solid part and a printing defect during printing. Moreover, sufficient image reproducibility cannot be obtained due to insufficient crosslinking density. In addition, if a photopolymerizable unsaturated compound having higher crosslinkability is used in order to obtain a high-quality image reproducibility, the printing plate material has a higher printing plate hardness, resulting in a decrease in ink deposition on the printing material and a good printed material. become unable. On the contrary, if the ratio of the photopolymerizable unsaturated compound in the photosensitive resin composition is large, the density of the cross-linked structure to be formed becomes excessive, so that the relief produced as a plate tends to crack in the relief during printing.
[0031]
Moreover, in this invention, a photoinitiator is mix | blended as (C) component. This has the capability to start polymerization by light irradiation with respect to the component (B). Examples include benzoin alkyl ethers, benzophenones, anthraquinones, benzyls, acetophenones, diacetyls, and the like. These photopolymerization initiators can be used in the range of 0.01 to 10% by weight based on the total amount of the photosensitive resin composition.
[0032]
In the photosensitive resin composition of the present invention, as a compatibilizer for a base resin, particularly a hydrophilic polymer and a photopolymerizable unsaturated compound, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, trimethylolpropane, trimethylolethane, etc. It is also possible to add polyhydric alcohols, N-ethyl-p-toluenesulfonamide, N-butylbenzenesulfonamide, N-methylbenzenesulfonamide and the like. These polyhydric alcohols and sulfonamide compounds have the effect of further enhancing the flexibility of the photopolymerization portion and preventing the occurrence of relief cracks. Such polyhydric alcohol and sulfonamide compound can be used in the range of 30% by weight or less based on the photosensitive resin composition.
[0033]
In order to improve the thermal stability of the photosensitive resin composition of the present invention, a conventionally known polymerization inhibitor can be used. Preferable thermal polymerization inhibitors include phenols, hydroquinones, catechols and the like. These thermal polymerization inhibitors can be used in the range of 0.001 to 5% by weight with respect to the total amount of the composition. In addition, dyes, pigments, surfactants, antifoaming agents, ultraviolet absorbers, fragrances, and the like can be added.
[0034]
As a method for producing the composition of the present invention, for example, a hydrophilic polymer and a vulcanized rubber blend polymer are heated and dissolved in a mixed solvent of water / alcohol, whereby only the hydrophilic polymer is dissolved and the micro-polymer in the molten mixture is dissolved. After the rubber dispersed in is diffused into the solution, an unsaturated epoxy compound is added to cause addition reaction to the polymer. Next, it is common to add a photopolymerizable unsaturated compound, a photopolymerization initiator and a heat stabilizer and mix them well by stirring. In this way, a photosensitive resin solution is obtained.
[0035]
Addition of an unsaturated epoxy compound to a solution of a molten mixture of a hydrophilic polymer and rubber, and addition of the unsaturated epoxy compound to the terminal carboxyl group of the hydrophilic polymer and rubber has made the polymer and rubber itself photopolymerizable. The relief network created by the photopolymerization reaction with the photopolymerizable compound is formed at a higher density, and the resulting relief has good water resistance and can maintain a high degree of image reproducibility. Is strong, it is possible to prevent problems such as cracking during printing.
[0036]
In order to form a photosensitive layer from the above mixed solution, for example, most of the solvent can be distilled and then heated to a molten state and extruded onto a support to be molded. It is also possible to form a photosensitive sheet by a dry film forming method and adhere this sheet on a support to form a photosensitive layer. Furthermore, the photosensitive layer can also be obtained by directly forming a dry film on the support. As the support, a metal plate such as steel, stainless steel, aluminum or copper, a plastic sheet such as polyester film, or a synthetic rubber sheet such as styrene-butadiene copolymer is used. The photosensitive layer is preferably formed to a thickness of 0.01 to 10 mm. Thus, the photosensitive resin plate material is obtained by coating the photosensitive resin composition of this invention on a support body.
[0037]
In order to form a printing plate using the photosensitive resin plate material of the present invention, a negative or positive original drawing film is brought into close contact with the photosensitive layer prepared as described above, and usually a high pressure centered on a wavelength of 300 to 400 mμ. Irradiate ultraviolet rays from mercury lamps, ultra-high pressure mercury lamps, metal halide lamps, xenon lamps, carbon arc lamps, and chemical lamps, and insolubilize them by photopolymerization. Next, a relief is formed on the support by eluting the unpolymerized portion into water with a spray developing device or a brush developing device using neutral water.
[0038]
This can be dried and then treated with actinic rays in air or in vacuum to obtain a printing plate.
[0039]
The photosensitive resin composition of the present invention has a high degree of image reproducibility and, if necessary, flexibility as a flexographic printing plate, has good water developability, and satisfies compatibility with water-based inks. Is.
[0040]
This is because the photosensitive resin composition itself can be developed in water by containing a hydrophilic polymer and rubber at a certain ratio, and the water-insoluble rubber is contained, so that the flexibility of the printing plate is improved. Further, the resistance to water-based inks in which a resin is dissolved in a solvent containing water as a main component is remarkably improved.
[0041]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples.
[0042]
The number of parts used in the following examples is parts by weight, and the number average molecular weight unless otherwise specified is a value obtained by combining the viscosity measurement method and the GPC method. The relative viscosity [ηr] is measured at 25 ° C. by dissolving the polymer in 98% sulfuric acid at a rate of 1 g / 100 cc.
[0043]
Hereinafter, synthesis examples of the hydrophilic polyamide used in each example will be described.
[0044]
Synthesis example
A-1: ε-caprolactam / equamolar salt of hexamethylenediamine and adipic acid / α, ω-diaminopropylpolyoxyethylene (number average molecular weight 1000) and equimolar salt of adipic acid = 20/20/60
The terminal groups of the copolymerized polyamide obtained here were quantified to be primary amino groups 4.0 × 10 −5 mol / g and carboxyl groups 2.1 × 10 −5 mol / g. The number average molecular weight was approximately 33,000.
[0045]
A-2: 113 g of ε-caprolactam, 17.6 g of hexamethylenediamine and 66 g of α-aminocaproic acid were charged into an autoclave, and after nitrogen substitution, the contents were reacted at a temperature of 230 ° C. for 3 hours. After cooling, 2 mg of 3-hydroxy-butanesulfonic acid lactone and 13.8 g of potassium sulfate were added to the reaction mixture. After purging with nitrogen, the reaction mixture was reacted again at a temperature of 230 ° C. for 1 hour to obtain a copolymerized polyamide.
[0046]
A-3: An autoclave was charged with 50 parts of N, N, -di (γ-aminopropyl) piperazine adipate, 30 parts of ε-caprolactam, 20 parts of water and 0.3 part of n-butylamine. After nitrogen replacement, seal and heat gradually. Internal pressure is 10kg / m ^Three From the time when the pressure reached, water was distilled until the pressure could not be maintained, the pressure was returned to normal pressure in about 2 hours, and then the reaction was performed at normal pressure for 1 hour. The maximum polymerization reaction temperature was 255 ° C. The obtained polymer was a transparent light yellow polyamide having a softening point of 90 to 105 ° C. and [ηr] 2.3.
[0047]
A-4: 90 parts of α-dimethylamino-ε-caprolactam and 10 parts of water are charged into an autoclave, purged with nitrogen, sealed and gradually heated. Internal pressure is 3.5kg / m ^Three From the time when the pressure reached, water was distilled until the pressure could not be maintained, the pressure was returned to normal pressure in about 2 hours, and then the reaction was performed at normal pressure for 2 hours. The maximum polymerization reaction temperature was 260 ° C. [Ηr] of the obtained polymer was 2.5.
[0048]
Example 1
Using a closed mixer operating at 160 ° C., 20 parts of the copolymerized polyamide obtained in Synthesis Example A-1 and 20 parts of carboxylated nitrile butadiene rubber (Nipol 1072 manufactured by Nippon Zeon Co., Ltd.) and partially crosslinked 20 parts of type nitrile butadiene rubber (Nipol DN214 manufactured by Nippon Zeon Co., Ltd.) and 40 parts of butadiene rubber (Nipol BR-1220L manufactured by Nippon Zeon Co., Ltd.) are melt-mixed for 10 minutes, and then 0.2 parts of m-phenylene bismaleimide. The total mixing time added was 15 minutes. Moreover, the form of this polymer blend was observed with a scanning electron microscope (JSM-T300 manufactured by JEOL Ltd., measurement conditions: reflected electron composition image). As a result of the observation, it was confirmed that the rubber obtained by vulcanizing A-1 polymer in the sea has a sea-island dispersion structure in which islands are formed, and the diameter of the spherical body is in the range of 0.5 to 4 microns.
[0049]
40 parts of the polymer blend thus obtained and 2 parts by weight of sodium methylenebisnaphthalene sulfonate were kneaded at 160 ° C. for 3 minutes in a closed mixer, and butadiene latex (Nipol LX111NF nonvolatile content 55% Nippon Zeon). Co., Ltd.) 10 parts solid equivalent, carboxy-modified acrylic butadiene latex (LM511-1 nonvolatile content 50% Dainippon Ink & Chemicals) 15 parts solid equivalent, and phenoxypolyethyleneglycol as a polymerizable unsaturated compound -Add 20 parts by weight of acrylate, 10 parts by weight of glycerin diglycidyl diacrylate and 2 parts by weight of N-stearyl gluconamide (Plastrogin J manufactured by Fujisawa Pharmaceutical Co., Ltd.), knead at 140 ° C. for 15 minutes, and further light Add 1 part by weight of dimethylbenzyl ketal as an initiator and add 10 Kneaded for minutes. The photosensitive resin composition thus obtained was heated to 140 ° C., and a polyester substrate having a thickness of 100 μm on which a polyester adhesive had been applied and cured in advance and polyvinyl alcohol had been applied in advance. The photosensitive resin composition was pressed between the existing polyester cover films so that the photosensitive layer had a thickness of 1700 μm to obtain a printing plate material.
[0050]
Further, the form of the plate material was observed with a scanning electron microscope (JSM-T300 manufactured by JEOL Ltd., measurement condition: reflected electron composition image). As a result of the observation, it has a sea-island dispersion structure composed of an A-1 polymer and a photopolymerizable unsaturated compound sea, an unvulcanized rubber, and an island of vulcanized rubber. It was confirmed to be in the range of 4 microns.
[0051]
On the photosensitive layer of this printing plate material, a gray scale negative film for sensitivity measurement (21 Steps Sensitivity Guide manufactured by Stouffer) and a negative film for image reproducibility evaluation (150 line 3%, 5%, 10% halftone dot, diameter 200 μm). , And 300 μm independent points, widths 50 and 70 μm with thin lines) were vacuum-contacted and exposed for 5 minutes from a distance of 5 cm with an exposure apparatus in which 15 20 W high-intensity chemical lamps were arranged.
[0052]
After the exposure was completed, development was performed with a brush-type washing machine (liquid temperature 35 ° C.) containing neutral water. A relief image having a depth of 1000 μm was formed in a development time of 5 minutes. As a result of evaluating this relief image, it was found that the gray scale portion remained up to 16 steps, and that the image line portion almost completely reproduced 3% halftone dots, 200 μm independent points, 50 μm fine lines, and the like. The printing plate had a Shore A hardness of 55 after completion of actinic ray post-exposure. Using this printing plate, a flexographic printing test of 100,000 sheets using a water-based ink was conducted, and a good printed matter was obtained.
[0053]
Comparative Example 1
In Example 1, the photosensitive resin printing plate material was obtained similarly to Example 1 except not using N-stearyl gluconamide. At this time, the moldability when pressing the photosensitive resin composition was poor. In order to obtain a printing plate in the same manner as in Example 1, a relief image having a depth of 1000 μm is formed with a brush type washing machine (liquid temperature 35 ° C.) containing neutral water. Development time was as long as 25 minutes.
[0054]
Comparative Example 2
A printing plate was obtained in the same manner as in Example 1 except that N-stearyl gluconamide in Example 1 was replaced with montan wax (manufactured by Wax OP Hoechst Co., Ltd.). At this time, the moldability when pressing the photosensitive resin composition was good, but in order to obtain a printing plate using this printing plate material in the same manner as in Example 1, after completion of exposure, washing with a brush containing neutral water was performed. The development time of 20 minutes was very slow to form a relief image having a depth of 1000 μm with a dashi machine (liquid temperature: 35 ° C.).
[0055]
Comparative Example 3
A printing plate was obtained in the same manner as in Example 1 except that N-stearyl gluconamide in Example 1 was replaced with ethylenebisstearic acid amide (Sripacs E Nippon Kasei Co., Ltd.). At this time, the moldability when pressing the photosensitive resin composition was good, but in order to obtain a printing plate using this printing plate material in the same manner as in Example 1, after completion of exposure, washing with a brush containing neutral water was performed. The development time of 20 minutes was very slow to form a relief image having a depth of 1000 μm with a dashi machine (liquid temperature: 35 ° C.).
[0056]
Example 2
A printing plate was obtained in the same manner as in Example 1 except that 1 part by weight of N-stearyl gluconamide was added when obtaining the polymer blend of Example 1. After the exposure was completed, development was performed with a brush-type washing machine (liquid temperature 35 ° C.) containing neutral water. A relief image having a depth of 1000 μm was formed in a development time of 4 minutes. As a result of evaluating this relief image, it was found that the gray scale portion remained up to 16 steps, and that the image line portion almost completely reproduced 3% halftone dots, 200 μm independent points, 50 μm fine lines, and the like. The printing plate had a Shore A hardness of 53 after the post-exposure of actinic rays. Using this printing plate, a flexographic printing test of 100,000 sheets using a water-based ink was conducted, and a good printed matter was obtained.
[0057]
【The invention's effect】
The photosensitive resin composition for printing plates of the present invention is excellent in high image reproducibility, has good water developability, and satisfies the compatibility with water-based inks. Further, when a hydrophilic polymer and rubber are used as the base resin, flexibility as a flexographic printing plate is provided.

Claims (8)

(A) Photosensitive for printing plates containing a compound having 3 or more hydroxyl groups, an amide bond and a hydrocarbon group having 6 or more carbon atoms in the molecule, (B) a polymerizable unsaturated compound and (C) a photopolymerization initiator Resin composition. The photosensitive resin composition for a printing plate according to claim 1, wherein the component (A) is an N-alkyl gluconamide compound represented by the general formula (I).

(Wherein R is an alkyl group having 6 to 24 carbon atoms) 3. The photosensitive resin composition for a printing plate according to claim 2, comprising 0.01 to 20% by weight of the N-alkyl gluconamide compound. Furthermore, the photosensitive resin composition for printing plates in any one of Claims 1-3 containing base resin. The printing plate photosensitive resin composition according to claim 4, wherein the base resin contains a hydrophilic polymer and a hydrophobic rubber. The photosensitive resin composition for a printing plate according to claim 5, wherein vulcanized rubber and unvulcanized rubber are dispersed in the hydrophilic polymer. The photosensitive resin plate material formed by coating the photosensitive resin composition for printing plates in any one of Claims 1-6 on a support body. The photosensitive resin plate material according to claim 7, which is used for flexographic printing.