JP2017032845A - Photosensitive resin composition for flexographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive resin composition which makes it possible to produce a printing plate having excellent water developability and capable of shortening plate-making time, and also having sufficient plate strength.SOLUTION: The present invention provides a photosensitive resin composition for flexographic printing plate comprising (A) hydrophilic compound, (B) thermoplastic elastomer, (C) liquid rubber, (D) polymerizable unsaturated monomer, (E) photopolymerization initiator, and (F) development promoter.SELECTED DRAWING: None

Description

  The present invention relates to a photosensitive resin composition used for producing a flexographic printing plate.

Among flexographic printing plates, common water-based developable solid plates for flexographic printing are hydrophilic copolymers made by emulsion polymerization, etc. on a support layer, hydrophobic resins such as thermoplastic elastomers, photopolymerization, etc. A structure in which a photosensitive resin composition layer in which a photosensitive unsaturated monomer and a photopolymerization initiator are mixed is formed, and a thin flexible film layer and a thin layer that can be ablated with an infrared laser are provided. Consists of.
A method for producing a printing plate from the structure is as follows: a transparent image carrier (negative film) is closely attached to the surface of the structure opposite to the support, and actinic rays are irradiated through the film to selectively select specific portions. After forming an image by photocuring, a relief is formed by removing an unexposed portion with an aqueous developer. In such a water-developable photosensitive resin composition for flexographic printing, there is a big problem of compatibility between water developability and printing durability in a state where water-based ink is attached.

Various proposals have been made as photosensitive resins that can be developed in water depending on the purpose.
For example, Examples of Patent Document 1 contain a hydrophilic polymer, a hydrophobic polymer, a plasticizer, a photopolymerizable unsaturated monomer and a photopolymerization initiator as a photosensitive resin composition, and a molecular weight as a plasticizer. Is a butadiene polymer, isoprene polymer or butadiene / isoprene block copolymer mixture having a styrene content of 10,000 to 6 and a 1,2-vinyl content of 25% or less. Here, it aims at providing the flexographic plate excellent in the developability by a water-system developing solution, plate strength, etc. However, since the molecular weight of the plasticizer is large and the hydrophilic component is small, developability and printing durability are insufficient.

  In Example 1 of Patent Document 2, as a photosensitive resin composition, maleic anhydride-modified polybutadiene, ethylene-vinyl acetate copolymer, photopolymerizable unsaturated monomer, polyether amide, polyester amide elastomer, heat Mixtures of stabilizers, photopolymerization initiators and gelling agents have been proposed. Here, an object is to provide a flexographic plate with improved printing resistance and raw plate strength. However, the printing durability is insufficient because there are few hydrophobic polymers and too many hydrophilic components.

  In Example 1 of Patent Document 3, a mixture of an anionic polyurethane, a cationic polymer, a photopolymerizable unsaturated monomer, a plasticizer, and a photopolymerization initiator is proposed as a photosensitive resin composition. . The object here is to provide a flexographic plate with improved printing resistance and high resilience. However, since an anionic polyurethane is used and there are too many hydrophilic components, the printing durability is insufficient.

JP 2004-246247 A JP-A-5-333543 JP-A-9-185168

  An object of this invention is to provide the photosensitive resin composition which is excellent in water developability, can shorten platemaking time, and can manufacture the printing plate which has sufficient plate strength.

  As a result of intensive studies to solve the above problems, the present inventor has (A) a hydrophilic compound, (B) a thermoplastic elastomer, (C) a liquid rubber, (D) a polymerizable unsaturated monomer, It has been found that the above problem can be solved by adding (F) a development accelerator to a photosensitive resin composition containing (E) a photopolymerization initiator.

That is, the present invention is as follows.
[1] (A) hydrophilic compound, (B) thermoplastic elastomer, (C) liquid rubber, (D) polymerizable unsaturated monomer, (E) photopolymerization initiator, and (F) development accelerator A photosensitive resin composition for flexographic printing plates.
[2] The photosensitive resin composition for flexographic printing plates according to [1], wherein the hydrophilic compound (A) is synthesized by emulsion polymerization.
[3] With respect to 100 parts by mass of the photosensitive resin composition for flexographic printing plates, (A) a hydrophilic compound is 15 to 40 parts by mass, (B) a thermoplastic elastomer is 10 to 40 parts by mass, and (C) a liquid rubber. 3 to 40 parts by weight, (D) 1 to 30 parts by weight of a polymerizable unsaturated monomer, (E) 0.1 to 10 parts by weight of a polymerization initiator, and (F) 0.1 to 0.1 parts by weight of a development accelerator. The photosensitive resin composition for flexographic printing plates according to [1] or [2], comprising 10 parts by mass.
[4] The photosensitive resin composition for flexographic printing plates according to any one of [1] to [3], wherein the development accelerator (F) is a polymer of acrylic acid neutralized with a base.

  Since the photosensitive resin composition for flexographic printing plates of the present invention has excellent water developability, it can be developed with water in a short time, and the photosensitive resin composition for flexographic printing plates of the present invention has sufficient plate strength. A flexographic printing plate having can be produced.

  A mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail below. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention. Deformation is possible.

[Hydrophilic compound (A)]
In the present embodiment, the hydrophilic compound (A) refers to a polymer at room temperature solid having at least one hydrophilic functional group, and preferably has a solubility in 100 g of pure water at 25 ° C. of less than 25 g. Examples of hydrophilic functional groups include carboxyl groups, sulfonic acid groups, phosphoric acid groups, boric acid groups, hydroxyl groups, and salts thereof. Specific examples include radical copolymers, polyamide polymers, polyvinyl alcohol polymers, polyester polymers, and urethane copolymers.

Examples of the radical copolymer include those obtained by copolymerization using 1.0 part by mass or more of a hydrophilic unsaturated monomer out of 100 parts by mass of the unsaturated monomer.
As the hydrophilic unsaturated monomer, an acidic functional group-containing unsaturated monomer is preferable, and as the acidic functional group-containing unsaturated monomer, a carboxyl group, a sulfonic acid group, a phosphoric acid group, a boric acid group or a hydroxyl group is used. An ethylenically unsaturated monomer having As for the usage-amount of an acidic functional group containing unsaturated monomer, 1-30 mass parts is preferable among the unsaturated monomer whole quantity. When the amount of the acidic functional group-containing unsaturated monomer is 1 part by mass or more with respect to the total amount of the unsaturated monomer, water development is good, and when it is 30 parts by mass or less, the moisture absorption amount of the photosensitive resin is kept below a certain level. Therefore, swelling due to the ink is suppressed, and the workability at the time of mixing when producing the photosensitive resin is maintained.
Specific examples of the hydrophilic unsaturated monomer used in the radical copolymer include conjugated dienes, aromatic vinyl compounds, ethylene monocarboxylic acid alkyl ester monomers having a hydroxyl group, maleic anhydride, and cyanide. Vinyl compounds, (meth) acrylamide and derivatives thereof, vinyl esters, vinyl ethers, vinyl halides, basic monomers having amino groups, vinyl pyridine, olefins, silicon-containing α, β-ethylenically unsaturated monomers Body, allyl compound and the like. These monomers may be used alone or in combination of two or more. Moreover, you may use the monomer which has a 2 or more addition-polymerizable group as a hydrophilic unsaturated monomer.

  The amount of the hydrophilic compound (A) used is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, with respect to 100 parts by mass of the photosensitive resin composition, and high physical properties of the printing plate. In terms of (elongation rate (elongation)), water resistance or ink swell resistance, 40 parts by mass or less is preferable, and 30 parts by mass or less is more preferable.

[Thermoplastic elastomer (B)]
In this embodiment, the thermoplastic elastomer (B) is preferably a room temperature solid polymer having no hydrophilic group, and specific examples include thermoplastic block copolymers, butadiene rubbers, isoprene rubbers, polyurethane elastomers, and the like. can do. Among these, a thermoplastic block copolymer that exhibits rubber elasticity near normal temperature, hardly undergoes plastic deformation, and is easily plasticized by heat when the composition is mixed with an extruder or the like is preferable.
Among the thermoplastic block copolymers, a thermoplastic elastomer obtained by polymerizing a monovinyl-substituted aromatic hydrocarbon monomer and a conjugated diene monomer is more preferable. Examples of monovinyl-substituted aromatic hydrocarbon monomers include styrene, α-methylstyrene, p-methylstyrene, p-methoxystyrene, and examples of conjugated diene monomers include butadiene and isoprene. Representative examples of thermoplastic elastomers include styrene-butadiene-styrene block copolymers and styrene-isoprene-styrene block copolymers. The content of the monovinyl-substituted aromatic hydrocarbon unit in 100 parts by mass of the thermoplastic elastomer (B) is 8 parts by mass or more from the viewpoint of suppressing cold flow resistance when the photosensitive resin plates before exposure are laminated. Preferably, 50 parts by mass or less is preferable from the viewpoint of keeping the hardness of the printing plate at a certain level or less and suppressing the deterioration of the printing quality. The average ratio of vinyl bonds in the conjugated diene segment of the thermoplastic elastomer is preferably 5% or more from the viewpoint of image reproducibility of the printing plate, and preferably 40% or less from the viewpoint of suppressing the tackiness of the printing plate surface. A range of 10 to 35% is more preferable. The average content of monovinyl-substituted aromatic hydrocarbon units and conjugated diene units in the thermoplastic elastomer and the average ratio of vinyl bond units in the thermoplastic elastomer can be determined by IR spectrum or NMR.
The amount of the thermoplastic elastomer (B) used is 10 parts by mass or more in terms of high physical properties (elongation rate (elongation)), water resistance or ink swell resistance of the printing plate out of 100 parts by mass of the photosensitive resin composition. It is preferably 20 parts by mass or more, and preferably 40 parts by mass or less, more preferably 35 parts by mass or less in terms of aqueous developability.

[Liquid rubber (C)]
In the present embodiment, the liquid rubber (C) refers to an elastomer that is liquid at 30 ° C., and includes those containing diene units. As the diene, isoprene and butadiene are preferable in terms of availability, and butadiene is more preferable in terms of anti-caking property. Two or more kinds of liquid conjugated diene rubbers may be used in combination. The liquid conjugated diene rubber may be modified with polar functional groups at both ends of the molecular chain. Examples of the polar functional group include a carboxyl group, an amino group, and a hydroxyl group.
The number average molecular weight (Mn) in the liquid rubber (C) is preferably low in terms of handleability and the compatibility of the photosensitive resin composition, while it is preferably high in terms of anti-caking property. Although it may be in the range of 1000 to 50000, the range of 2000 to 30000 is more preferable, and the range of 3000 to 20000 is more preferable.
The content of the liquid rubber (C) is preferably 3 parts by mass or more, more preferably 20 parts by mass or more, in 100 parts by mass of the photosensitive resin composition in terms of image reproducibility, anti-choke property and flexibility. 40 mass parts or less are preferable and 35 mass parts or less are more preferable at the point of the solid maintenance property of the photosensitive structure for printing plates.

[Polymerizable unsaturated monomer (D)]
The polymerizable unsaturated monomer (D) is an unsaturated monomer that can be radically polymerized by radicals generated from a polymerization initiator. Examples thereof include esters such as acrylic acid, methacrylic acid, fumaric acid and maleic acid, acrylamide and methacrylamide derivatives, allyl esters, styrene and derivatives thereof, and N-substituted maleimide compounds. Specific examples include diacrylates and dimethacrylates of alkanediols such as hexanediol and nonanediol; diacrylates and diacrylates of alkylene glycols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, and butylene glycol. Trimethylolpropane triacrylate and trimethacrylate; pentaerythritol tetraacrylate and tetramethacrylate; N, N′-hexamethylenebisacrylamide and methacrylamide; styrene, vinyltoluene, divinylbenzene, diacrylphthalate, triallyl cyanurate , Diethyl fumarate, dibutyl fumarate, dioctyl fumarate, Fumarate distearyl ester, fumarate butyl octyl ester, fumarate diphenyl ester, fumarate dibenzyl ester, maleate dibutyl ester, maleate dioctyl ester, fumarate bis (3-phenylpropyl) ester, fumarate dilauryl ester, Examples thereof include fumaric acid diphenyl ester and N-laurylmaleimide. These may be used alone or in combination of two or more.
The amount of the polymerizable unsaturated monomer (D) used is preferably 1 part by mass or more and more preferably 5 parts by mass or more in terms of fine points and character formability with respect to 100 parts by mass of the photosensitive resin composition. Preferably, it is preferably 30 parts by mass or less, more preferably 20 parts by mass or less in terms of keeping the cold flow resistance and the hardness of the printing plate constant when the pre-exposure photosensitive resin plate is laminated, and suppressing deterioration in printing quality. preferable.

[Photoinitiator (E)]
The photopolymerization initiator (E) is an initiator that generates radicals by irradiation with light such as ultraviolet rays.
Examples of the photopolymerization initiator (E) include benzophenone, 4,4-bis (diethylamino) benzophenone, t-butylanthraquinone, 2-ethylanthraquinone, 2,4-diethylthioxanthone, isopropylthioxanthone, and 2,4-dichlorothioxanthone. Thioxanthones such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino (4-thiomethyl) Acetophenones such as phenyl) propan-1-one and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone; benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether Benzoin ethers such as benzoin isobutyl ether; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6) Acylphosphine oxides such as -trimethylbenzoyl) -phenylphosphine oxide; methylbenzoylformate, 1,7-bisacridinylheptane, 9-phenylacridine and the like. These may be used alone or in combination of two or more.
As for the usage-amount of a photoinitiator (E), 0.1-10 mass parts is preferable with respect to 100 mass parts of photosensitive resin compositions. 0.1 parts by mass or more is preferable in terms of fine points and character formability, 1 part by mass or more is more preferable, and 10 parts by mass or less is preferable in terms of reduction in exposure sensitivity due to a decrease in transmittance of active light such as ultraviolet rays. 5 parts by mass or less is more preferable.

[Development accelerator (F)]
In the present embodiment, the development accelerator (F) refers to a polymer having water solubility, water swellability or water dispersibility (excluding the hydrophilic compound (A)), and relative to 100 g of pure water at 25 ° C. A water-soluble polymer that dissolves 25 g or more is preferred.
Specific examples of the development accelerator (F) include polyacrylic acid, polyacrylate, polymethacrylate, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, isobutylene-maleic anhydride copolymer, water-soluble polyamide, water-soluble Examples thereof include a flexible polyurethane, polyethyleneimine, polystyrene sulfonic acid, and polystyrene sulfonate. Among these, polyacrylates (polymers of acrylic acid neutralized with a base) such as sodium polyacrylate, partially saponified polyvinyl alcohol, and isobutylene that have high water solubility and high affinity with other components. -Maleic anhydride copolymer and water-soluble polyurethane are preferred. These may be used alone or in combination of two or more.
The amount of the development accelerator (F) used is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the photosensitive resin composition. The amount is preferably 0.1 part or more, more preferably 0.5 part by weight or more from the viewpoint of development acceleration effect, preferably 10 parts or less, more preferably 5 parts by weight or less, from the viewpoint of swelling resistance and anti-scratch resistance to ink. .

[Others]
In addition to the essential components described above, various auxiliary additive components such as antioxidants, ultraviolet absorbers, antihalation agents, light stabilizers, and the like may be added to the photosensitive resin composition of the present embodiment as desired. it can.

[Photosensitive resin composition, method for producing photosensitive resin plate]
The photosensitive resin composition of this embodiment can be manufactured by mixing each said component (A)-(F) and arbitrary additives using an extruder, a kneader, etc.
The photosensitive resin composition of the present embodiment can be formed into a photosensitive resin composition layer having a desired thickness by hot press molding, calendar treatment, or extrusion molding. This photosensitive resin composition layer may be used as it is as a photosensitive resin plate (original plate), or in order to maintain the accuracy as a printing plate, a support such as polyester is used for the photosensitive resin composition by roll lamination or the like. It is good also as a photosensitive resin plate by sticking to a layer and laminating | stacking. Furthermore, a highly accurate photosensitive resin plate can also be obtained by heat-pressing after lamination.
Moreover, since the photosensitive resin composition of the present embodiment may cause stickiness depending on the composition, the contact property with the transparent image carrier (negative film) superimposed thereon is improved, and the image carrier For reuse, a flexible film layer that can be removed with an aqueous developer may be provided on the surface of the photosensitive resin composition layer on which the relief is formed.

  In the photosensitive resin plate using the photosensitive resin composition of the present embodiment, the photosensitive resin composition layer is exposed to a desired image like an actinic ray and photocured, and then an uncured portion is removed by development. A relief image can be created to make a flexographic printing plate.

[exposure]
Examples of the active light source used for photocuring the photosensitive resin composition layer 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, and sunlight.
After the photosensitive resin composition layer is irradiated with light to form an image, an uncured uncured portion is removed (developed) using an aqueous developer to obtain a relief.

[developing]
Examples of the developer used in combination with the photosensitive resin composition of the present embodiment include water or an aqueous developer containing water and a surfactant. Examples of the surfactant include nonionic, anionic, cationic and amphoteric surfactants, and these may be used alone or in admixture of two or more.
Specific examples of the anionic surfactant include linear alkylbenzene sulfonate having an alkyl having an average carbon number of 8 to 16, an α-olefin sulfonate having an average carbon number of 10 to 20, an alkyl group or an alkenyl group. A dialkyl sulfosuccinate having 4 to 10 carbon atoms, a sulfonate of a fatty acid lower alkyl ester, an alkyl sulfate having an average carbon number of 10 to 20, a linear or branched alkyl or alkenyl group having an average carbon number of 10 to 20 Alkyl ether sulfates having an average of 0.5 to 8 moles of ethylene oxide and saturated or unsaturated fatty acid salts having an average carbon number of 10 to 22 and the like.
Specific examples of the cationic surfactant include alkylamine salts, alkylamine ethylene oxide adducts, alkyltrimethylammonium salts, alkyldimethylbenzylammonium salts, sapamine-type quaternary ammonium salts, and pyridium salts.
Specific examples of nonionic surfactants include polyethylene glycol type higher alcohol alkylene oxide adducts, alkylphenol alkylene oxide adducts, fatty acid alkylene oxide adducts, polyhydric alcohol fatty acid ester alkylene oxide adducts, and higher alkyl amine alkylenes. Oxide adducts, fatty acid amide alkylene oxide adducts, fat and oil alkylene oxide adducts, and polypropylene glycol alkylene oxide adducts, polyhydric alcohol fatty acid esters of glycerol, fatty acid esters of pentaerythritol, fatty acid esters of sorbitol and sorbitan, Examples include fatty acid esters of sugars, alkyl ethers of polyhydric alcohols, and fatty acid amides of alkanolamines.
Specific examples of the amphoteric surfactant include sodium laurylaminopropionate and lauryldimethylbetaine. Although there is no restriction | limiting in particular in the density | concentration of surfactant, Usually, it is used in 0.5-10 mass parts with respect to the developing solution whole quantity.

If necessary, the developer may contain a development aid such as a cleaning accelerator and a pH adjuster in addition to the surfactant. Examples of the cleaning accelerator include amines such as monoethanolamine, diethanolamine and triethanolamine; glycol ethers; ammonium salts such as tetramethylammonium hydroxide; or paraffinic hydrocarbons. Examples of the pH adjusting agent include sodium borate, sodium carbonate, sodium silicate, sodium metasilicate, sodium succinate, sodium acetate, and the like. The development aids can be used alone or in admixture of two or more.
The boiling point of the development aid is preferably 130 ° C. or higher at normal pressure. When the boiling point is lower than this, when the water is evaporated from the developer and recovered as a condensate, a considerable amount of the solvent tends to be simultaneously washed away into the water. Alternatively, when this is used for the purpose of adjusting the concentration of the developing solution, it takes time and effort to measure and adjust the amount of the entrained solvent in order to stabilize the performance of the developing solution. If necessary, an antifoaming agent, a dispersant, a corrosion inhibitor, and an anti-corruption agent may be used in combination.

  The photosensitive resin plate using the photosensitive resin composition of the present embodiment is developed after the exposure, after removing the uncured resin composition in the unexposed area. Development is performed by removing the resin composition in the unexposed area with a developing machine equipped with a brush or the like using the above aqueous developer, and the resin composition in the unexposed area is eluted in the developer. Distributed.

The flexographic printing plate obtained as described above is preferably dried after development, optionally washed with water and the like. Although there is no limitation on drying conditions, for example, it is preferable to dry at about 60 ° C. for 15 to 120 minutes in an oven or the like.
Depending on the composition of the photosensitive resin composition, stickiness may remain on the plate surface even after the drying is finished. In that case, stickiness can be removed by a known surface treatment method. As such a surface treatment method, an exposure treatment with actinic rays having a wavelength of 300 nm or less is preferable.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention more concretely, this invention is not limited to these Examples.

The present invention will be described based on examples.
[Examples 1-9, Comparative Examples 1-3]
(1) Synthesis of hydrophilic compound (A) In a pressure-resistant reaction vessel equipped with a stirrer and a temperature control jacket, 125 parts by mass of water and an emulsifier (α-sulfo- (1- (nonylphenoxy) methyl-2- (2- Propenyloxy) ammonium salt of ethoxy-poly (oxy-1,2-ethanediyl), (trade name: Adecalia Soap SE1025 (Asahi Denka Kogyo)) is initially charged, and the internal temperature is raised to the polymerization temperature. 2 parts by mass of acrylic acid, 5 parts by mass of methacrylic acid, 60 parts by mass of butadiene, 15 parts by mass of styrene, 18 parts by mass of 2-ethylhexyl acrylate and 2 parts by mass of t-dodecyl mercaptan and 28 parts by mass of water, peroxo 1.2 parts by weight of sodium disulfate, 0.2 parts by weight of sodium hydroxide and an emulsifier (trade name: Adekaria Soap SE1025 (Asahi Den 1) 1 part by weight of an aqueous solution was added at a constant flow rate over 5 hours and 6 hours, respectively, and kept at the same temperature for 1 hour to complete the polymerization reaction, followed by cooling. After adjusting the pH of the copolymer latex to 7 with sodium hydroxide, unreacted monomers are removed by a steam stripping method and filtered through a 200 mesh wire net. % To obtain a hydrophilic copolymer solution (aqueous dispersion of hydrophilic compound (A)).
The number average particle size of the hydrophilic copolymer was 40 nm. The particle diameter was determined as a number average particle diameter using a particle size analyzer (trade name: MICROTRC particle size analyzer (model: 9230UPA) (manufactured by Nikkiso Co., Ltd.)). Got.

(2) Preparation of photosensitive resin composition and photosensitive resin plate Hydrophilic compound (A) obtained in (1), liquid rubber (C) in the mass ratio shown in Table 1, development accelerator shown in Table 1 (F) (sodium polyacrylate, partially saponified polyvinyl alcohol, isobutylene-maleic anhydride copolymer or water-soluble polyurethane) and 2,6-di-t-butyl-p-cresol as an antioxidant are mixed. A composition obtained by removing water using an evaporator and an open kneader, and a styrene-butadiene block copolymer (trade name: Kraton D-KX405 (manufactured by Kraton Polymer Japan)) as the thermoplastic elastomer (B) The mixture was mixed at 120 ° C. for 5 minutes at a mass ratio shown in Table 1 using a pressure kneader. In the obtained composition, 2,2-dimethoxyphenylacetophenone as a polymerizable unsaturated monomer (D) and a photopolymerization initiator (E) described in Table 1 were added at a mass ratio shown in Table 1 for 10 minutes. Was added little by little, and after addition was completed, the mixture was further kneaded for 5 minutes to obtain a photosensitive resin composition.
The photosensitive resin composition was taken out, and a polyethylene terephthalate (PET) film having a thickness of 100 μm coated with an adhesive using a thermoplastic elastomer on one side and polyvinyl alcohol (PVA) having a thickness of 5 μm were coated on one side. Sandwiched with a 100 μm thick PET film and formed into a 1 mm thick plate-like laminate at 120 ° C. using a press machine to obtain a photosensitive resin plate.

(3) Preparation of printing plate The photosensitive resin plate obtained in (2) is exposed to an ultraviolet light exposure machine (from the side of the PET film coated with an adhesive so that the thickness of the cured layer is about 0.5 mm) The product was exposed using a product name: JE-A2-SS (manufactured by JEOL Ltd.).
Next, the PVA-coated PET film was peeled off so that the PVA remained on the photosensitive resin surface, and the negative film of the printed image was brought into close contact therewith and exposed for 10 minutes with the exposure machine.
After exposure, the negative film is peeled off to prepare an aqueous solution (aqueous developer) of 4 wt% higher alcohol alkylene oxide adduct, 0.4 wt% diethylene glycol dibutyl ether, 0.5 wt% diethylene glycol monohexyl ether and 0.4 wt% sodium carbonate. Then, using a washing machine (trade name: JOW-A3-P (manufactured by JEOL Seiki)), washing was performed at 40 ° C. (development), and unexposed portions were removed.
After drying, it was post-exposed with an ultraviolet germicidal lamp or an ultraviolet chemical lamp to prepare a printing plate.

(4) Evaluation (a) Developability with aqueous developer (development time)
Using the above aqueous developer and washing machine, the unexposed photosensitive resin plate is washed for 10 minutes, the thickness (t) of the resin layer reduced by washing is measured, and 10 min / t (mm) is calculated. The time required for 1 mm development (1 mm development time) (min / mm) was calculated.
The developing time should be short, and the 1 mm developing time is less than 10 min, ◯, 10 min or more and less than 12 min / mm is Δ, and 12 min / mm or more is ×.
(B) Plate wiping resistance (scratch resistance)
The term “plate wiping resistance” refers to the degree of difficulty of damaging the printing plate image portion in the operation of wiping off the water-based ink. The strength of the plate wiping resistance was measured in a pseudo manner. A printing plate having characters of 8 to 12 points in size is made using a negative film, immersed in 10% isopropyl alcohol aqueous solution (room temperature) instead of water-based ink for 16 hours, and then subjected to NP type printing durability tester. Destruction of characters when rubbed 300 times to the left and right using a cloth (made by Shinmura Printing Co., Ltd., contacted 3: 8 cm x 6 cm in size (product name: Hightecloth (manufactured by Kanebo)), load 1 kg) The degree of was observed with a microscope.
As the evaluation of the plate-proof wiping resistance of the printing plate, ○ if the character was not destroyed, △ if the number of destroyed characters was 1, and x if the number of destroyed characters was 2 or more. .

  Table 1 shows the physical property evaluation test results obtained by the above method for the resin compositions and printing plates obtained in Examples 1 to 9 and Comparative Examples 1 to 3. As a comprehensive evaluation, a case that passed both of the evaluations (a) and (b) was evaluated as ◯, at least one as ◯ or Δ as Δ, and both as X. From Table 1, in Examples 1 to 9 in which the development accelerator (F) was added to the photosensitive resin composition, the photosensitive resin composition exhibited excellent water developability and had sufficient plate strength. A flexographic printing plate could be obtained.

  The photosensitive resin composition of the present invention can be suitably used when a flexographic printing plate is produced using an aqueous developer.

Claims (4)

  A flexo comprising (A) a hydrophilic compound, (B) a thermoplastic elastomer, (C) a liquid rubber, (D) a polymerizable unsaturated monomer, (E) a photopolymerization initiator, and (F) a development accelerator. Photosensitive resin composition for printing plates.   (A) The photosensitive resin composition for flexographic printing plates of Claim 1 whose hydrophilic compound is what was synthesize | combined by emulsion polymerization.   (A) 15-40 parts by weight of hydrophilic compound, (B) 10-40 parts by weight of thermoplastic elastomer, and (C) liquid rubber, 3 parts by weight with respect to 100 parts by weight of the photosensitive resin composition for flexographic printing plates. 40 parts by mass, (D) 1-30 parts by mass of a polymerizable unsaturated monomer, (E) 0.1-10 parts by mass of a polymerization initiator, and (F) 0.1-10 parts by mass of a development accelerator. The photosensitive resin composition for flexographic printing plates of Claim 1 or 2 containing.   (F) The photosensitive resin composition for flexographic printing plates of any one of Claim 1 to 3 whose development accelerator is a polymer of acrylic acid neutralized with a base.