JP2018180048A - Photosensitive resin composition for flexographic printing plates and method for producing the same, and flexographic printing original plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive resin composition that makes it possible to obtain a flexographic printing original plate having high detergency of aqueous developer, and having excellent printing durability.SOLUTION: A photosensitive resin composition for flexographic printing plates contains at least a hydrophilic copolymer (A), an elastomer (B), a polymerizable unsaturated monomer (C), and a photopolymerization start material, where the hydrophilic copolymer (A) has a structure derived from a coupling material (E).SELECTED DRAWING: None

Description

  The present invention relates to a photosensitive resin composition for flexographic printing plate, a method for producing the same, and a flexographic printing original plate.

  Flexographic printing is a type of letterpress printing, and uses a soft material such as rubber or synthetic resin for the printing plate, and therefore has the advantage of being applicable to various printing materials.

  The printing plate used for flexographic printing is a method of making a plate using a negative film from the old days, and a computer plate making technology (hereinafter referred to as CTP technology) of producing relief by directly drawing information processed on a computer on a printing plate. In recent years, it has become mainstream to be manufactured by the CTP technology.

The original plate of the flexographic printing plate has different plate configurations when using a negative film and when using CTP technology. Although both of the case of using a negative film and the case of using CTP technology are common in that a photosensitive layer made of a photosensitive resin composition is provided on a substrate such as PET resin, but using a negative film In the case of using the CTP technology and the case of using the CTP technology, what is configured on the photosensitive layer is different. First, in the case of using a negative film, there is a transparent image carrier layer for protecting the negative film from the tackiness of the photosensitive layer, and the negative film is brought into close contact on the transparent image carrier layer before use. The layer is irradiated with UV light to remove the uncured portion to form a relief image. On the other hand, in the case of using the CTP technology, an infrared ablation layer is laminated on the photosensitive layer, and the infrared ablation layer is directly drawn with a laser or the like, and then the photosensitive layer is irradiated with ultraviolet light to remove the uncured portion. Form an image.
Recently, a relief image may be formed by removing the uncured portion with a water-based developer (water development).

  By the way, in general, in a photosensitive resin printing plate for flexographic printing capable of aqueous development, a hydrophobic resin such as a hydrophilic copolymer or an elastomer, a polymerizable unsaturated monomer, or the like on a support for maintaining dimensional accuracy. The photosensitive layer which consists of a photosensitive resin composition which mixed a monomer, a photoinitiator, etc. is formed.

  In the photosensitive resin composition used for such a photosensitive layer, each component in the composition is preferably finely and uniformly dispersed in order to faithfully obtain the required image, and the plate-making time is shortened. For this reason, it is preferable that the development speed be fast. Furthermore, after plate-making, since it is necessary to endure the use of aqueous ink and it is necessary to wash out the adhered ink with water, it is preferable that the water swelling ratio after curing be low, and naturally, the printing durability is preferably high.

  As a water-developable photosensitive resin composition, for example, Patent Document 1 discloses a photosensitive resin composition in which a sulfonic acid surfactant is contained and the rubber forms a dispersed phase having a size of 10 μm or less. It is done.

  Patent Document 2 discloses a photosensitive resin composition containing an aqueous dispersion latex, a photopolymerizable monomer, a millable rubber, a maleic acid half ester, and a photopolymerization initiator. Further, Patent Document 3 discloses a photosensitive resin composition containing an aqueous dispersion latex, a photopolymerizable monomer having a molecular weight of 1000 or less, a rubber, and a photopolymerization initiator. Furthermore, Patent Document 4 discloses a photosensitive resin composition containing an aqueous dispersion latex, a photopolymerizable monomer, a rubber, and a photopolymerization initiator.

Patent No. 5325823 gazette JP, 2014-19708, A Patent No. 5401840 Patent No. 5228572 gazette

  However, the aqueous developable photosensitive resin compositions described in Patent Documents 1 and 2 have problems that the water resistance of a printing plate using the same is low or the printing durability after ink deposition is reduced. There is.

  On the other hand, the water-based developable photosensitive resin compositions described in Patent Documents 3 and 4 have a problem that the water resistance and the printing durability of the printing plate are high, but the developability to a water-based developer is low.

  As described above, conventional photosensitive resin compositions used for printing base plates for flexographic printing are required to have good developability for aqueous developers and water resistance and printing durability after being made into printing plates. Despite this, there are contradictory aspects, and it is difficult to achieve both.

  Then, an object of the present invention is to provide a photosensitive resin composition which can obtain an original plate for flexographic printing which has high washability to an aqueous developer and is excellent in printing durability.

  As a result of intensive studies on such problems, the present inventor found that at least (A) hydrophilic copolymer, (B) elastomer, (C) photopolymerizable unsaturated monomer, and (D) photopolymerization initiator By using a photosensitive resin composition for a flexographic printing plate, which contains the following structure and the hydrophilic copolymer (A) has a structure derived from the coupling material (E): We have found that we can simultaneously achieve both the plate's superior press life and complete the invention.

That is, the present invention is as follows.
[1]
At least a hydrophilic copolymer (A), an elastomer (B), a polymerizable unsaturated monomer (C), and a photopolymerization initiator,
The hydrophilic copolymer (A) has a structure derived from a coupling material (E),
Photosensitive resin composition for flexographic printing plates.
[2]
The coupling material (E) is a compound represented by formula (I) or formula (II):
The photosensitive resin composition for flexographic printing plates as described in [1].
X _3-n (CH ₃ ) _n -Si- (CH ₂ ) _m -Y ... (I)
(In the formula, X represents a hydrolyzable group, Y represents an organic functional group, n represents 0, 1 or 2, and m represents 1 to 6.)
Y-(CH ₂ ) _m- Y ..... (II)
[In formula, Y shows an organic functional group and m shows 1-6. ]
[3]
The hydrolyzable group X in the formula (I) is at least one selected from the group consisting of a methoxy group (CH ₃ O—) and an ethoxy group (CH ₃ CH ₂ O—),
Formula (II) an organic functional group Y in is amino (-NH _2), a vinyl group (-CH = CH _2), acryloxy group (-OOCCH = CH _2), methacryloxy group (-OOCC (CH ₃₎ = CH ₂ ), isocyanate group (-N = C = O), mercapto group (-SH), sulfur atom (-S-), ureido group (-NHCONH ₂ ), oxetanyl group, and epoxy group (-C- ( And at least one selected from the group consisting of -O-)-C-),
The photosensitive resin composition for flexographic printing plates as described in [2].
[4]
30 parts by mass or more and 250 parts by mass or less of the elastomer (B) and 10 parts by mass or more and 200 parts by mass of the polymerizable unsaturated monomer (C) with respect to 100 parts by mass of the hydrophilic copolymer (A) The photopolymerization initiator (D) is contained in an amount of 0.1 parts by mass or more and 50 parts by mass or less.
The photosensitive resin composition for flexographic printing plates in any one of [1]-[3].
[5]
At least one selected from the group consisting of surfactants, (meth) acrylic acid ester monomers having polyalkylene glycol chains, and compounds having an acid value of 10 mg KOH / g to less than 400 mg KOH / g and containing a carboxylic acid structure. 0.1 to 15 parts by mass of the compound (F) is further contained,
The photosensitive resin composition for flexographic printing plates in any one of [1]-[4].
[6]
The plasticizer component (G) is further contained in an amount of 1.0 to 250 parts by mass with respect to 100 parts by mass of the hydrophilic copolymer (A).
The photosensitive resin composition for flexographic printing plates in any one of [1]-[5].
[7]
The hydrophilic copolymer (A) is an internally crosslinked polymer particle comprising a unit derived from a reactive emulsifier containing an unsaturated double bond,
The photosensitive resin composition for flexographic printing plates in any one of [1]-[6].
[8]
It is a manufacturing method of the photosensitive resin composition for flexographic printing plates in any one of [1]-[7],
Coupling agent (E) containing a polymerizable bonding group, surfactant, (meth) acrylic acid ester monomer having polyalkylene glycol chain in aqueous dispersion containing hydrophilic copolymer (A) A step of adding at least one compound (F) selected from the group consisting of a compound having an acid value of 10 mg KOH / g to less than 400 mg KOH / g and containing a carboxylic acid, and / or a plasticizer component (G)
Water is removed from the aqueous dispersion containing the hydrophilic copolymer (A) to obtain a mixture containing the hydrophilic copolymer (A), and a mixture containing the hydrophilic copolymer (A) And (e) adding an elastomer (B), a polymerizable unsaturated monomer (C), and a photopolymerization initiator (D).
[9]
It has a photosensitive layer containing the photosensitive resin composition for flexographic printing plates in any one of [1]-[8],
Flexographic printing original plate.

  According to the photosensitive resin composition according to the present invention, it is possible to obtain an original plate for flexographic printing which has a high cleaning property to an aqueous developer and is excellent in printing durability.

  Although the form (henceforth "this embodiment") for carrying out the present invention is explained in detail below, the present invention is not limited to this, and various modification in the range which does not deviate from the gist Is possible.

[Photosensitive resin composition for flexographic printing plate]
The photosensitive resin composition for a flexographic printing plate of the present embodiment comprises at least (A) a hydrophilic copolymer, (B) an elastomer, (C) a photopolymerizable unsaturated monomer, and (D) a photopolymerization initiator Contains In addition, the hydrophilic copolymer (A) has a structure derived from the coupling material (E).

  In this embodiment, the photosensitive resin composition for flexographic printing plates can be suitably used for the photosensitive resin composition layer of flexographic printing plates by an aqueous developer. This factor is due to the hydrophilic copolymer (A) having a structure derived from the coupling material, so that when the flexographic printing plate is formed, the photosensitive resin composition layer forms a so-called sea-island structure, resulting in hydrophilic coweight It is guessed that it originates in suppressing the cohesive failure in the island structure which a combination (A) forms.

(Hydrophilic copolymer (A))
In the present embodiment, the hydrophilic copolymer (A) means internally cross-linked polymer particles containing a unit derived from a hydrophilic unsaturated monomer. The unit derived from the hydrophilic unsaturated monomer is, for example, preferably 0.1% by mass to 20% by mass, and more preferably 0 based on the total amount (100% by mass) of the monomer units. 0.5 to 15% by mass, and more preferably 1% to 10% by mass. As such polymer particles, for example, polymer particles obtained by emulsion polymerization using a hydrophilic unsaturated monomer and, if necessary, another monomer copolymerizable therewith, can be used. What is obtained by removing water from an aqueous dispersion latex dispersed in water as a dispersoid is mentioned.

  As the hydrophilic unsaturated monomer, a monomer containing at least one hydrophilic group and an unsaturated double bond is preferable. For example, carboxylic acid, sulfonic acid, phosphoric acid, etc. or a salt or acid anhydride thereof Monomers containing unsaturated double bonds, monomers containing hydroxyl and unsaturated double bonds, monomers containing acrylamide and unsaturated double bonds, reactive unsaturated double bonds Surfactant (monomer) etc. are mentioned. Only one type of these compounds may be used, or two or more types may be used at the same time.

  Such a water dispersion latex is not particularly limited. For example, acrylonitrile-butadiene copolymer latex, polychloroprene latex, polyisoprene latex, polyurethane latex, (meth) acrylate-butadiene latex, vinylpyridine polymer latex, butyl And water-dispersible latex polymers such as polymer latex, thiocol polymer latex, and acrylate polymer latex, and the like, and these water-dispersible latexes include (meth) acrylate, acrylic acid, methacrylic acid, crotonic acid, vinyl benzoic acid, etc. Acid, a carboxylic acid such as cinnamic acid, a sulfonic acid such as styrene sulfonic acid, an acid functional group-containing non-basic acid such as itaconic acid, fumaric acid, maleic acid, citraconic acid, or muconic acid Saturated monomer One or more copolymerized shall also preferred.

  In addition to the polymer particles obtained by emulsion polymerization using a hydrophilic unsaturated monomer and, if necessary, another monomer copolymerizable therewith, in the above-mentioned water dispersion latex, Furthermore, other polymer particles may be contained as a dispersoid. Such other polymers include, for example, polybutadiene, natural rubber, and a styrene-butadiene copolymer.

  Among these, a water dispersion latex containing a butadiene skeleton or an isoprene skeleton in the molecular chain is preferable from the viewpoint of printing durability. Specifically, polybutadiene latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, and / or water dispersion latex of these, (meth) acrylate, acrylic acid, methacrylic acid, itaconic acid, etc. What copolymerized is preferable. More preferably, it is a copolymer obtained by copolymerizing one or more kinds of an acid functional group-containing unsaturated monomer such as (meth) acrylic acid ester, acrylic acid, methacrylic acid, itaconic acid and the like to a styrene-butadiene copolymer It is a water dispersion latex.

  The amount of the acidic functional group-containing unsaturated monomer used is 1% by mass or more and 30% by mass or less of the total amount (100% by mass) of the unsaturated monomer used for the synthesis of the hydrophilic copolymer (A) Is preferred. When the amount used is 1% by mass or more, aqueous development tends to be facilitated. On the other hand, when the amount used is 30% by mass or less, the moisture absorption amount of the photosensitive resin composition increases, and the ink It tends to be possible to suppress the deterioration of the processability at the time of mixing of the photosensitive resin composition due to an increase in the amount of swelling of the above.

  The unsaturated monomer other than the acidic functional group-containing unsaturated monomer that can be used for the synthesis of the hydrophilic copolymer (A) is not particularly limited, and examples thereof include conjugated dienes, aromatic vinyl compounds, Meta) acrylic acid ester, ethylenic monocarboxylic acid alkyl ester monomer having a hydroxyl group, unsaturated dibasic acid alkyl ester, maleic anhydride, vinyl cyanide compound, (meth) acrylamide and derivatives thereof, vinyl esters, vinyl ether , Halogenated vinyls, basic monomers having an amino group, vinyl pyridine, olefins, silicon-containing α, β-ethylenically unsaturated monomers, allyl compounds and the like.

  The conjugated diene is not particularly limited. For example, 1,3-butadiene, isoprene, 2,3-dimethyl 1,3-butadiene, 2-ethyl-1,3-butadiene, 2-methyl-1,3-butadiene And 1,3-pentadiene, chloroprene, 2-chloro-1,3-butadiene, cyclopentadiene and the like.

  The aromatic vinyl compound is not particularly limited. For example, styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ethylstyrene, vinyltoluene, vinylxylene, bromostyrene, vinylbenzyl Chloride, p-t-butylstyrene, chlorostyrene, alkylstyrene, divinylbenzene, trivinylbenzene and the like can be mentioned.

  The (meth) acrylic acid ester is not particularly limited. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, Isobutyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl hexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate , Cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, 2-ethyl-hexyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl ( ) Acrylate, hydroxycyclohexyl (meth) acrylate, glycidyl (meth) acrylate, ethylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, 1,3- butylene glycol di (meth) acrylate, 1,4- butylene glycol Di (meth) acrylate, propylene glycol di (meth) acrylate, 1,5-pentanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, diethylene glycol di ( Meta) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene Cole di (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, allyl (meth) acrylate, bis (4-acryloxypolyethoxyphenyl) propane, Methoxypolyethylene glycol (meth) acrylate, β- (meth) acryloyloxyethyl hydrogen phthalate, β- (meth) acryloyloxyethyl hydrogen succinate, 3-chloro-2-hydroxypropyl (meth) acrylate, stearyl (meth) ) Acrylate, phenoxyethyl (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, 2-hydroxy-1,3-di (meth) acryloxy prop 2,2-bis [4-((meth) acryloxyethoxy) phenyl] propane, 2,2-bis [4-((meth) acryloxydiethoxy) phenyl] propane, 2,2-bis [4- ( (Meth) acryloxy-polyethoxy) phenyl] propane, isobornyl (meth) acrylate and the like.

  The ethylene-based monocarboxylic acid alkyl ester monomer having a hydroxyl group is not particularly limited. For example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate 1-hydroxypropyl acrylate, 1-hydroxypropyl methacrylate, hydroxycyclohexyl (meth) acrylate and the like.

  The unsaturated dibasic acid alkyl ester is not particularly limited, and examples thereof include crotonic acid alkyl ester, itaconic acid alkyl ester, fumaric acid alkyl ester, and maleic acid alkyl ester.

  The vinyl cyanide compound is not particularly limited, and examples thereof include acrylonitrile and methacrylonitrile.

  Although it does not specifically limit as (meth) acrylamide and its derivative (s), For example, (meth) acrylamide, N- methylol (meth) acrylamide, N- alkoxy (meth) acrylamide etc. are mentioned.

  The vinyl esters are not particularly limited, and examples thereof include vinyl acetate, vinyl butyrate, vinyl stearate, vinyl laurate, vinyl myristate, vinyl propionate, vinyl versatate and the like.

  The vinyl ethers are not particularly limited, and examples thereof include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, amyl vinyl ether, hexyl vinyl ether and the like.

  The halogenated vinyls are not particularly limited, and examples thereof include vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride and the like.

  The basic monomer having an amino group is not particularly limited, and examples thereof include aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate and the like.

  The olefin is not particularly limited, and examples thereof include ethylene and the like.

  The silicon-containing α, β-ethylenically unsaturated monomer is not particularly limited, and examples thereof include vinyltrichlorosilane, vinyltriethoxysilane and the like.

  The allyl compound is not particularly limited, and examples thereof include allyl ester and diallyl phthalate.

  Although it does not specifically limit as unsaturated monomers other than another acidic functional group containing unsaturated monomer, For example, the monomer which has 3 or more double bonds, such as triallyl isocyanurate, is mentioned.

  These monomers may be used alone or in combination of two or more. The weight ratio of conjugated diene to other monomers is preferably between 5/95 and 95/5, more preferably between 50/50 and 90/10. When the mass ratio is in this range, deterioration of the rubber elasticity of the photosensitive resin composition for a flexographic printing plate can be suppressed.

  The hydrophilic copolymer (A) is preferably synthesized by emulsion polymerization, and in this case, it is preferable to use a reactive emulsifier as an emulsifier (surfactant) used at the time of polymerization. By using a reactive emulsifier, the hydrophilic copolymer (A) can contain units derived from the reactive emulsifier.

  As the reactive emulsifying agent, one having a radically polymerizable unsaturated double bond, a hydrophilic functional group and a hydrophobic group in the molecular structure, and having an emulsifying, dispersing, and wetting function as in the general emulsifying agent is preferable. . By using such a reactive emulsifying agent, the hydrophilic copolymer (A) can be obtained to be internally crosslinked polymer particles containing units derived from the reactive emulsifying agent containing unsaturated double bonds. . In addition, when the hydrophilic copolymer (A) is emulsion-polymerized, an average particle size of at least 0.1 parts by mass with respect to 100 parts by mass of the unsaturated monomer excluding the reactive emulsifier is used. An emulsifying (surfactant) agent is preferred so that a polymer having a diameter of 5 to 500 nm can be synthesized. In addition, it is more preferable that the hydrophilic emulsifier (A) is a polymer particle in which the hydrophilic copolymer (A) is internally crosslinked when the reactive emulsifier contains an unsaturated double bond.

  Although it does not specifically limit as a structural example of the radically polymerizable double bond in molecular structure, For example, a vinyl group, acryloyl group, methacryloyl group etc. are mentioned. Examples of the hydrophilic functional group in the molecular structure are not particularly limited. For example, anionic groups such as sulfuric acid group, nitric acid group, phosphoric acid group, boric acid group and carboxyl group; Cationic groups such as amino group; And polyoxyalkylene chain structures such as oxyethylene, polyoxymethylene, polyoxypropylene and the like; or hydroxyl groups and the like. The hydrophobic group in the molecular structure may, for example, be an alkyl group or a phenyl group.

  Reactive emulsifiers include anionic emulsifiers, nonionic emulsifiers, cationic emulsifiers, amphoteric emulsifiers and the like depending on the kind of hydrophilic functional group contained in the structure. Moreover, the radically polymerizable double bond in a molecular structure, a hydrophilic functional group, and a hydrophobic group may each be contained in multiple types.

  The anionic surfactant is not particularly limited, as it is generally commercially available among those usable as the reactive emulsifier in the present embodiment, and examples thereof include Adekaria Soap SE (Asahi Denka Kogyo), Aqualon HS. And BC and KH (Daiichi Kogyo Seiyaku Co., Ltd.), Latemule S (Kao), Antox MS (Nippon Emulsifier), Adekaria Soap SDX and PP (Asahi Denka Kogyo), Hythenol A (Daiichi Kogyo Seiyaku Co., Ltd.), Eleminol RS ( Non-ionic surfactants include, but not particularly limited to, for example, Aqualon RN, Neugen N (Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria Soap NE (Asahi Denka) Industrial). These may be used alone or in combination of two or more.

  In the present embodiment, the amount of the reactive emulsifier used is in the range of 1 part by mass to 20 parts by mass with respect to 100 parts by mass of the hydrophilic copolymer (A) calculated from the preparation amount of the raw material preferable. When the amount of the reactive emulsifier is 1 part by mass or more, the image reproducibility of the obtained printing plate tends to be improved, and when it is 20 parts by mass or less, the printing resistance of the obtained printing plate tends to be improved. is there.

  In the present embodiment, when the hydrophilic copolymer (A) is synthesized by emulsion polymerization, if necessary, a non-reactive emulsifier can also be used.

  Here, the non-reactive emulsifying agent used as necessary is not particularly limited, but, for example, anions such as fatty acid soap, rosin acid soap, sulfonate, sulfate, phosphate ester, polyphosphate ester, acyl salicylate and the like Surfactants; Cationic surfactants such as nitrileated oil / fat derivatives, oil / fat derivatives, fatty acid derivatives, α-olefin derivatives, etc. Alcohol ethoxylates, alkylphenol ethoxylates, propoxylates, aliphatic alkanolamides, alkyl polyglycosides, polyoxyethylene sorbitan Nonionic surfactants such as fatty acid esters and oxyethylene oxypropylene block copolymers can be mentioned. These may be used alone or in combination of two or more.

  The sulfonate is not particularly limited. For example, alkyl sulfonate, alkyl sulfate, alkyl sulfosuccinate, polyoxyethylene alkyl sulfate, sulfonated oil, alkyl diphenyl ether disulfonate, α-olefin sulfonate , Alkyl glyceryl ether sulfonate, N-acylmethyl taurate and the like.

  Other examples of these surfactants include those described in “Surfactant Handbook (Takahashi, Namba, Koike, Kobayashi: Engineering Manual, 1972)”.

  It is preferable that the usage-amount of a non-reactive emulsifier is less than 1 mass part with respect to 100 mass parts of hydrophilic copolymers (A) calculated from the preparation amount of a raw material. When the amount is less than 1 part by mass, the obtained printing plate exhibits an appropriate water swelling rate, and tends to be able to suppress the reduction in abrasion resistance when ink is attached and the reduction in image reproducibility after moisture absorption. .

  In the emulsion polymerization method of the hydrophilic copolymer (A), a predetermined amount of water, an emulsifying agent and other additives are charged in advance in a reaction system prepared at a polymerizable temperature, and a polymerization initiator and an unsaturated single monomer are added to this system. It is general to add a monomer, an emulsifier, a modifier and the like into the reaction system in a batch operation or a continuous operation. In addition, it is a commonly used method that, if necessary, a predetermined amount of a seed latex, an initiator, an unsaturated monomer, and other modifiers are charged in advance in the reaction system.

  It is also possible to change the layer structure of the hydrophilic copolymer particles synthesized in stages by devising the method of adding unsaturated monomers, emulsifiers, other additives, and modifiers to the reaction system. is there. In this case, the physical properties representing the structure of each layer include hydrophilicity, glass transition point, molecular weight, crosslinking density and the like. Also, the number of stages of this layer structure is not particularly limited.

  In the present embodiment, known chain transfer agents can be used for the polymerization of the hydrophilic copolymer (A). The chain transfer agent containing elemental sulfur is not particularly limited, and examples thereof include alkanethiols such as t-dodecyl mercaptan and n-dodecyl mercaptan; thioalkyl alcohols such as mercaptoethanol and mercaptopropanol; thioglycolic acid and thiopropionic acid And thioalkyl carboxylic acids such as thioglycolic acid octyl ester and thiopropionic acid octyl ester; and sulfides such as dimethyl sulfide and diethyl sulfide. In addition, examples of chain transfer agents include, but are not limited to, for example, halogenated hydrocarbons such as terpinorene, dipentene, t-terpinene and carbon tetrachloride. Among these, alkanethiols are preferable because they have a high chain transfer rate and a well-balanced physical property of the resulting polymer.

  These chain transfer agents may be used alone or in combination of two or more. These chain transfer agents may be mixed with the monomers and supplied to the reaction system or may be independently added in predetermined amounts at predetermined times. The amount of these chain transfer agents used is preferably 0.1% by mass or more and 10% by mass or less based on the total amount (100% by mass) of unsaturated monomers used for the polymerization of the hydrophilic copolymer (A). It is. When the content is 0.1% by mass or more, deterioration in processability when the photosensitive resin composition is mixed can be suppressed, and when the content is 10% by mass or less, the decrease in molecular weight is suppressed. Tend to

  In the present embodiment, a polymerization reaction inhibitor can be used for the polymerization of the hydrophilic copolymer (A), if necessary.

  The polymerization reaction inhibitor is a compound that reduces the radical polymerization rate by adding to the emulsion polymerization system. More specifically, a polymerization rate retarder, a polymerization inhibitor, a chain transfer agent having low radical reinitiation reactivity, and a monomer having low radical reinitiation reactivity. The polymerization reaction inhibitor is generally used to adjust the polymerization reaction rate and adjust the physical properties of the latex. These polymerization reaction inhibitors are added to the reaction system in batch operation or continuous operation. When a polymerization reaction inhibitor is used, the strength of the latex film is improved, and the printing durability is improved. Although the details of the reaction mechanism are unknown, the polymerization reaction inhibitor seems to be closely involved in the steric structure of the polymer, and it is presumed that this is effective in adjusting the physical properties of the latex film.

  The polymerization reaction inhibitor is not particularly limited. For example, quinones such as o-, m- or p-benzoquinone; Nitro compounds such as nitrobenzene, o-, m- or p-dinitrobenzene; such as diphenylamine Amines; catechol derivatives such as tert-butyl catechol; 1,1-disubstituted vinyl compounds such as 1,1-diphenylethylene or α-methylstyrene, 2,4-diphenyl-4-methyl-1-pentene; Examples thereof include 1,2-disubstituted vinyl compounds such as 2,4-diphenyl-4-methyl-2-pentene and cyclohexene. In addition to this, "POLYMER HANDBOOK 3rd Ed. (J. Brandup, E. H. Immergut: John Wiley & Sons, 1989)", "Revision of Polymer Synthesis Chemistry (Otsu: Chemical Doujin, 1979.)" The compounds described as inhibitors or polymerization inhibitors may be mentioned. Among these, 2,4-diphenyl-4-methyl-1-pentene (α-methylstyrene dimer) is more preferable in terms of reactivity. These polymerization reaction inhibitors may be used alone or in combination of two or more.

  It is preferable that the usage-amount of these polymerization reaction inhibitors is 10 mass% or less with respect to the unsaturated monomer whole quantity (100 mass%) used for superposition | polymerization of a hydrophilic copolymer (A). When the content is 10% by mass or less, a decrease in polymerization rate tends to be suppressed.

  The radical polymerization initiator is to cause radical decomposition in the presence of heat or a reducing substance to initiate addition polymerization of the monomer, and either an inorganic initiator or an organic initiator can be used. Such materials are not particularly limited, and examples thereof include water-soluble or oil-soluble peroxodisulfates, peroxides, azobis compounds, etc. Specifically, potassium peroxodisulfate, sodium peroxodisulfate, etc. And ammonium peroxodisulfate, hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide, 2,2-azobisbutyronitrile, cumene hydroperoxide and the like, and others such as POLYMER HANDBOOK (3rd edition), J. Am. Brandrup and E.I. H. The compounds described in Immergut, John Willy & Sons (1989) may be mentioned. In addition, a so-called redox polymerization method may be employed in which a reducing agent such as sodium acid sulfite, ascorbic acid or a salt thereof, erythorbic acid or a salt thereof or Rongalite is used in combination with a polymerization initiator. Among these, peroxodisulfate is particularly preferable as a polymerization initiator. The amount of the polymerization initiator used is preferably in the range of 0.1% by mass or more and 5.0% by mass or less, more preferably 0.2% by mass, with respect to the total amount (100% by mass) of the unsaturated monomer. It is the range of mass% or more and 3.0 mass% or less. When it is 0.1 mass% or more, stability at the time of synthesis of the hydrophilic copolymer tends to be easily obtained, and when it is 5.0 mass% or less, the moisture absorption amount of the photosensitive resin composition is increased. Tend to be able to

  In the present embodiment, various polymerization modifiers can be added as needed during the synthesis of the hydrophilic copolymer (A). The pH adjuster is not particularly limited, and examples thereof include sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium hydrogencarbonate, sodium carbonate, disodium hydrogenphosphate and the like. Also, various chelating agents such as sodium ethylenediaminetetraacetate can be added as a polymerization regulator. Further, other additives are not particularly limited, but, for example, alkali sensitive latex, viscosity reducing agent such as hexametaphosphoric acid, water soluble polymer such as polyvinyl alcohol and carboxymethyl cellulose, thickener, various anti-aging agents, ultraviolet light Absorbents, preservatives, disinfectants, antifoaming agents, dispersants such as sodium polyacrylate, water resistance agents, metal oxides such as zinc flower, crosslinkers such as isocyanate compounds, epoxy compounds, lubricants, water retention agents, etc. And various additives. The addition method of these additives is not particularly limited, and can be added at the time of synthesis of the hydrophilic copolymer, regardless of after synthesis.

  In this embodiment, the polymerization temperature in the case of emulsion polymerization of the hydrophilic copolymer (A) is preferably selected in the range of 60 to 120 ° C., but the polymerization is carried out at a lower temperature by the above-mentioned redox polymerization method or the like. You may go. Furthermore, as the redox catalyst, a metal catalyst such as divalent iron ion, trivalent iron ion, copper ion and the like may be made to coexist.

  The hydrophilic copolymer (A) is preferably in the form of particles, and the average particle diameter thereof is more preferably 500 nm or less, and still more preferably 100 nm or less. When the average particle size is 500 nm or less, the decrease in aqueous developability of the obtained printing plate precursor tends to be suppressed.

  Moreover, it is preferable that the toluene gel fraction of a hydrophilic copolymer (A) is 60 to 99%. When the gel fraction is 60% or more, the decrease in strength of the obtained printing plate is suppressed, and when it is 99% or less, the mixing property of the hydrophilic copolymer (A) and the elastomer (B) is suppressed. It tends to suppress the decline.

  Here, with the toluene gel fraction, an appropriate amount of about 30% by mass dispersion of the hydrophilic copolymer (A) is dropped on a Teflon (registered trademark) sheet and dried at 130 ° C. for 30 minutes to be hydrophilic. 0.5 g of the hydrophobic copolymer (A), which is immersed in 30 mL of toluene at 25.degree. C., shaken for 3 hours using a shaker, and then filtered through a 320 SUS mesh, and 130.degree. The mass fraction (%) obtained by dividing the mass after time drying by 0.5 (g).

(Elastomer (B))
In the present embodiment, the elastomer (B) means an elastomer exhibiting rubber elasticity at normal temperature (25 ° C.). Although it does not specifically limit as an elastomer (B), For example, a thermoplastic block copolymer, a polybutadiene, polyacrylonitrile butadiene, a polyurethane-type elastomer etc. are mentioned. Among them, thermoplastic block copolymers are preferred.

  The thermoplastic block copolymer is preferably one obtained by polymerizing a monovinyl-substituted aromatic hydrocarbon monomer and a conjugated diene monomer, and the monovinyl-substituted aromatic hydrocarbon monomer is not particularly limited, and examples thereof include styrene, α, -Methylstyrene, p-methylstyrene, p-methoxystyrene and the like can be mentioned. The conjugated diene monomer is not particularly limited, and for example, butadiene, isoprene and the like can be mentioned.

  Although it does not specifically limit as a specific thermoplastic block copolymer, For example, a styrene- butadiene- styrene block copolymer, a styrene- isoprene- styrene copolymer, etc. are mentioned. Here, in the styrene-butadiene-styrene block copolymer and the styrene-isoprene-styrene copolymer, a diblock body such as a styrene-butadiene copolymer or a styrene-isoprene copolymer may be mixed. . In addition, styrene and butadiene or isoprene may be randomly copolymerized with the butadiene portion or the isoprene portion in the styrene-butadiene-styrene block copolymer or the styrene-isoprene-styrene copolymer.

  Here, the content of the monovinyl-substituted aromatic hydrocarbon unit in the elastomer (B) suppresses the cold flow of the photosensitive resin composition when it is contained in a fixed amount to obtain good thickness accuracy, and also by a fixed amount or less In some cases, the hardness of the flexographic printing plate is suppressed, and good printing quality can be obtained. Preferably, the content is in the range of 8.0% by mass to 50% by mass with respect to the total amount (100% by mass) of the resin composition. .

  The vinyl-bonded units in the conjugated diene segment of the elastomer (B) contribute to the improvement of the reproducibility of the relief, but at the same time also contribute to the improvement of the tackiness of the flexographic printing plate surface. From the viewpoint of balancing these two characteristics, the average ratio of vinyl bond units is preferably 5% by mass to 40% by mass, and more preferably 10% by mass to 35% by mass.

  The average content of the monovinyl-substituted aromatic hydrocarbon unit and the conjugated diene unit, and the average ratio of vinyl-bonded units in the conjugated diene segment of the elastomer (B) can be determined by IR spectrum or NMR.

  In the photosensitive resin composition, the content of the elastomer (B) is preferably 30 parts by mass or more and 250 parts by mass or less with respect to 100 parts by mass of the hydrophilic copolymer (A). More preferably, it is 30 parts by mass or more and less than 200 parts by mass, and still more preferably 50 parts by mass or more and less than 100 parts by mass.

  By being 30 parts by mass or more, there is a tendency to suppress a decrease in printing durability and an increase in the swelling ratio of the ink having polarity, and by being 250 parts by mass or less, a decrease in developability with an aqueous developer Tend to

(Polymerizable unsaturated monomer (C))
The polymerizable unsaturated monomer (C) used in the present embodiment is not particularly limited, and examples thereof include carboxylic acid esters such as acrylic acid, methacrylic acid, fumaric acid and maleic acid, acrylamide and methacrylamide Derivatives, allyl esters, styrene and derivatives thereof, N-substituted maleimide compounds and the like can be mentioned.

  Specific examples thereof include, but are not particularly limited to, diacrylates and dimethacrylates of alkanediols such as hexanediol and nonanediol, or diacrylates of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol and butylene glycol And dimethacrylate, or trimethylolpropane triacrylate and trimethacrylate, pentaerythritol tetraacrylate and tetramethacrylate, etc., N, N'-hexamethylene bisacrylamide and methacrylamide, styrene, vinyl toluene, divinylbenzene, diacryl phthalate, Triallyl cyanurate, fumaric acid diethyl ester, fumaric acid dibutyl ester, dioctyl fumarate Stel, fumaric acid distearyl ester, fumaric acid butyl octyl ester, fumaric acid diphenyl ester, fumaric acid dibenzyl ester, maleic acid dibutyl ester, maleic acid dioctyl ester, fumaric acid bis (3-phenylpropyl) ester, fumaric acid dilauryl Ester, fumaric acid dibehenyl ester, N-lauryl maleimide etc. are mentioned. These may be used alone or in combination of two or more.

  In the photosensitive resin composition, the content of the polymerizable unsaturated monomer (C) is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 100 parts by mass of the hydrophilic copolymer (A). Is 20 parts by mass or more and less than 150 parts by mass, and more preferably 30 parts by mass or more and less than 100 parts by mass. It is preferable in order to improve the formation of a fine point or a character as it is 10 mass parts or more. When the amount is 200 parts by mass or less, deformation of the uncured plate during storage and transportation is suppressed, and the hardness of the obtained plate becomes appropriate, and printing on a poor-quality printing material with uneven surface It is preferable because it produces an effect such that the ink coverage of the solid portion is improved.

(Photopolymerization initiator (D))
The photopolymerization initiator (D) used in the present embodiment is not particularly limited. For example, benzophenone, Michler's ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, α-methylol benzoin Α-Methylolbenzoin methyl ether, α-Methoxybenzoin methyl ether, Benzoimphenyl ether, α-tert-Butylbenzoin, 2,2-Dimethoxyphenylacetophenone, 2,2-Diethoxyphenylacetophenone, Benzyl, Pivaloin, Anthracene A quinone, benzanthraquinone, 2-ethyl anthraquinone, 2-chloroanthraquinone etc. are mentioned. These may be used alone or in combination of two or more.

  In the photosensitive resin composition, the content of the photopolymerization initiator (D) is preferably 0.1 parts by mass or more and less than 50 parts by mass with respect to 100 parts by mass of the hydrophilic copolymer (A). More preferably, it is 1 part by mass or more and less than 30 parts by mass. If the amount is 0.1 parts by mass or more, the formability of fine points and characters tends to be improved. Moreover, in the case of 50 mass parts or less, it exists in the tendency which can ensure active light transmittance | permeability, such as an ultraviolet-ray of the photosensitive resin composition, and can maintain exposure sensitivity.

(Coupling material (E))
In the photosensitive resin composition, the content of the unit derived from the coupling material (E) is 1% by mass or more relative to the total amount (100% by mass) of the hydrophilic copolymer (A) containing the unit. It is preferable to be under mass%. The content of the coupling material is more preferably 2% by mass to 15% by mass, and still more preferably 5% by mass to 10% by mass. In the case of 1 part by mass or more, the printing durability and the cleaning properties tend to be good, and in the case of 20 parts by mass or less, when the flexographic printing original plate is prepared and then laminated, the resin layer is pushed by the load and flows It tends to be difficult.

The coupling material (E) used in the present embodiment is not particularly limited as long as it contains a bonding group that can be polymerized to the hydrophilic copolymer (A). The compound represented by these is mentioned.
X _3-n (CH ₃ ) _n -Si- (CH ₂ ) _m -Y ... (I)
(In the formula, X represents a hydrolyzable group, Y represents an organic functional group, n represents 0, 1 or 2, and m represents 1 to 6.)
Y-(CH ₂ ) _m- Y ..... (II)
[In formula, Y shows an organic functional group and m shows 1-6. ]

Here, the hydrolyzable group X in the formula (I) (II) is not particularly limited as long as it is a functional group to be hydrolyzed, and examples thereof include a methoxy group (CH ₃ O-) and an ethoxy group (CH ₃ CH ₂ O -), 2-methoxyethoxy group (CH ₃ OCH ₂ CH ₂ O-) and the like, and as the organic functional group Y, amino group (-NH ₂ ), vinyl group (-CH = CH ₂ ), acrylic group (-CH ₂ ) -OOCCH = CH _2), methacryl group _{(-OOCC (CH 3) = CH} 2), isocyanate group (-N = C = O), mercapto group (-SH), a sulfur atom (-S-), an ureido group ( -NHCONH _2), an epoxy group (-C - (- O -) - C-) shows the like. Among these, hydrolyzable group X is a methoxy group (CH ₃ O-), and represents at least one selected from the group consisting of ethoxy (CH ₃ CH ₂ O-), an organic functional group Y is an amino group (-NH ₂ ), vinyl group (-CH = CH ₂ ), acryloxy group (-OOCCH = CH ₂ ), methacryloxy group (-OOCC (CH ₃ ) = CH ₂ ), isocyanate group (-N = C =) O), a mercapto group (-SH), a sulfur atom (-S-), an ureido group (-NHCONH _2), Okisetataniru group, and epoxy group (-C - (- O -) - C-) selected from the group consisting of It is preferable to show at least one of

  The coupling agent (E) is not particularly limited. For example, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, vinyltriethoxysilane, 3-glycidyloxypropyl-trimethoxysilane, 3 And -ethyl oxetan-3-yl) methyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether and the like. Among them, preferred are 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, and 4-hydroxybutyl acrylate glycidyl ether. One or more of these coupling materials may be used in combination.

  In the present embodiment, the coupling agent (E) is added to the hydrophilic copolymer (A) -containing aqueous dispersion, and when removing water, the carboxylic acid present on the surface of the hydrophilic copolymer (A) It is hydrolyzed by the acid, and further introduced into the hydrophilic copolymer (A) by condensation, hydrogen bonding or the like. The coupling agent (E) can also be introduced by forming a salt with the above-mentioned carboxylic acid, or by addition reaction, crosslinking reaction, and copolymerization reaction.

  As a form by which a coupling agent (E) is introduce | transduced into a hydrophilic copolymer (A), for example with respect to the carboxylic acid which exists on the surface of a hydrophilic copolymer (A), a coupling agent (E) is mentioned. Of forming a salt with an amino group of A), forming a urethane bond by condensation with an isocyanate group of a coupling material (E), and forming a hydrogen bond with a silanol group of a coupling material (E) Aspects can be mentioned. Also, an embodiment in which a bond is formed by an addition reaction with a mercapto group possessed by the coupling material (E), for example, with respect to the double bond of butadiene present on the surface of the hydrophilic copolymer (A), and The aspect which forms the bond by the crosslinking reaction with the sulfur atom which E) has is mentioned. Furthermore, the vinyl moiety of the hydrophilic copolymer (A) or the monomer thereof is copolymerized (crosslinked) with, for example, a vinyl group, an acryloxy group or a methacryloxy group that the coupling material (E) has. The aspect which forms a bond, and the aspect which forms the bond by the copolymerization (bridge | crosslinking) reaction with the epoxy group or oxetanyl group which coupling agent (E) has are mentioned. Furthermore, the combination of the aspect mentioned above is also mentioned.

(Compound (F))
In the embodiment, the photosensitive resin composition contains a surfactant, a (meth) acrylic acid ester monomer having a polyalkylene glycol chain, and an acid value of 10 mg KOH / g or more and less than 400 mg KOH / g, and contains a carboxylic acid structure. And at least one compound (F) selected from the group consisting of

  The surfactant of the compound (F) which can be used in the present embodiment is not particularly limited, and examples thereof include anionic surfactants, ionic surfactants, nonionic surfactants, and anionic reactive surfactants. And nonionic reactive surfactants.

  Specifically, sodium polyoxyethylene styrenated phenyl ether sulfate, sodium polyoxyalkylene branched decyl ether sulfate, sodium ammonium polyoxyethylene isodecyl ether sulfate, sodium polyoxyethylene tridecyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, poly Oxyethylene lauryl ether ammonium sulfate, sodium polyoxyethylene alkyl ether sulfate, polyoxyethylene oleyl cetyl ether ammonium sulfate, polyoxyethylene oleyl cetyl ether sodium, polyoxyethylene tridecyl ether phosphate, polyoxyethylene alkyl (C2 to C16) Ether phosphate ester, polyoxyethylene alkyl (C2-C16) ether Acid ester monoethanolamine salt, alkyl (C2-C16) phosphoric acid ester sodium, alkyl (C2-C16) phosphoric acid ester monoethanolamine salt, disodium laurylsulfosuccinate, polyoxyethylene sodium laurylsulfosuccinate, Polyoxyethylene alkyl (C2-C20) sulfosodium disuccinate, sodium linear alkyl benzene sulfonate, linear alkyl benzene sulfonic acid, sodium alpha-olefin sulfonate, phenol sulfonic acid, sodium dioctyl sulfosuccinate, sodium lauryl sulfate, higher fatty acid potassium salt Anionic surfactants such as, alkyl (C8-C20) trimethyl ammonium chloride, alkyl (C8-C20) dimethyl ethyl ammonium Loride, didecyldimethyl ammonium chloride, lauryl dimethyl benzyl ammonium chloride, stearyl dimethyl hydroxyethyl ammonium para toluene sulfonate, stearyl dimethylamino propyl amide, tributyl benzyl ammonium chloride, lauryl dimethylamino acetic acid betaine, lauric amido propyl betaine, coconut oil fatty acid amide Ionic surfactants such as propyl betaine, octano acid amido propyl betaine, lauryl dimethyl amine oxide, polyoxyalkylene tridecyl ether, polyoxyethylene isodecyl ether, polyoxyalkylene lauryl ether, polyoxyalkylene alkyl ether, polyoxyalkylene Mixture of ether and polyether polyol, Riether polyol, polyoxyethylene sulfonated phenyl ether, polyoxyethylene naphthyl ether, phenoxyethanol, polyoxyethylene phenyl ether, polyoxyethylene polyoxypropylene glycol, polyoxyethylene lauryl ether, polyoxyethylene oleyl cetyl ether, polyoxyethylene glycol Len oleate ester, polyoxyethylene distearate ester, polyoxyethylene glyceryl isostearate, polyoxyethylene hydrogenated castor oil, coconut oil fatty acid diethanolamide, polyoxyethylene alkylamine, sorbitan trioleate, sorbitan sesquiolate, sorbitan monooleate, Sorbitan monococolate, sorbitan monocaprate, polyoxyethylene sorbita Monococoate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, octyl polyglycoside, butyl polyglycoside, sucrose benzoate, sucrose acetate, non-ionic surfactant of sucrose fatty acid ester, polyoxy Anionic reactive surfactants such as ammonium ethylene-1- (allyloxymethyl) alkyl ether sulfate and polyoxyethylene nonylpropenyl phenyl ether sulfate, and nonionic reactive surfactants such as polyoxyethylene nonyl propenyl phenyl ether It can be mentioned.

  Further, the (meth) acrylic acid ester monomer having a polyalkylene glycol chain of the compound (F) which can be used in the present embodiment is not particularly limited, but, for example, two or more ethylene glycol chains as a monomer having a polyalkylene glycol Polyethylene glycol mono (acrylate) containing in the range of 20 or less, polyethylene glycol di (meth) acrylate, polyethylene glycol mono (meth) acrylate containing the propylene glycol chain in the range of 2 to 20, polypropylene glycol di (meth) acrylate, polyethylene Polyethylene glycol polypropylene glycol di (meth) acrylate, cresyl polyethylene glycol containing glycol chain and / or polypropylene glycol chain in the range of 2 to 20 respectively Lumpur (meth) acrylate, nonyl phenoxy polyethylene glycol (meth) acrylate.

  The compound containing a carboxylic acid structure of the compound (F) which can be used in the present embodiment is not particularly limited, and, for example, a polymer having a carboxyl group in at least one kind of repeating unit (hereinafter, "carboxylic acid modified acrylic polymer It is also referred to as ". Moreover, as a commercial item, liquid carboxylic acid modified | denatured acrylic polymer [CB-3060, CB-3098, CBB-3060, the product made by SOKEN CHEMICAL], [BR-605, made by Mitsubishi Rayon] etc. are mentioned.

  Here, the carboxylic acid-modified acrylic polymer can also be prepared by synthesis, and can be prepared, for example, with reference to Toho Synthetic Research annual report, TREND, 1999, second issue, 20 to 26. Specifically, the carboxylic acid-modified acrylic polymer can be synthesized by reacting acrylic acid, a polymerization initiator such as sodium persulfate, and a chain transfer agent such as isopropyl alcohol. Here, the acid value can be controlled to be 10 mg KOH / g or more and less than 400 mg KOH / g by appropriately adjusting the reaction temperature, and the addition amount of the polymerization initiator and the chain transfer agent.

  The compounds (F) may be used alone or in combination of two or more.

  Among these compounds (F), nonionic surfactants, nonionic reactive surfactants, and (meth) acrylic acid ester monomers having a polyalkylene glycol chain are preferred.

  In the photosensitive resin composition, the content of the compound (F) is preferably 0.1 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the hydrophilic copolymer (A). More preferably, it is 0.5 parts by mass or more and less than 10 parts by mass. When the amount is 0.1 parts by mass or more, the decrease in the developability of the aqueous developer tends to be suppressed, and when the amount is 15 parts by mass or less, the haze of the obtained resin composition becomes high, or after development The drying time of the ink tends to be prolonged, and the solvent resistance to water-based ink tends to be reduced.

(Plasticizer component (G))
In the present embodiment, the photosensitive resin composition may further contain a plasticizer component (G).

  The plasticizer component (G) is not particularly limited, and examples thereof include hydrocarbon oils such as naphthenic oil and paraffin oil, liquid polybutadiene, liquid polyisoprene, terminal modified products of liquid polybutadiene, liquid acrylonitrile-butadiene copolymer, Examples thereof include carboxylic acid modified products of liquid acrylonitrile-butadiene copolymer, liquid styrene-butadiene copolymer, polystyrene having a number average molecular weight of 2,000 or less, sebacic acid ester, phthalic acid ester, carboxylic acid-modified acrylic polymer and the like.

  Among them, liquid polybutadiene, terminally modified product of liquid polybutadiene modified with OH group or carboxyl group, liquid acrylonitrile-butadiene copolymer, carboxylic acid modified product of liquid acrylonitrile-butadiene copolymer, liquid styrene-butadiene copolymer Combined and carboxylic acid modified acrylic polymers are preferred.

  Liquid polybutadiene, terminal modified product of liquid polybutadiene, liquid acrylonitrile-butadiene copolymer, carboxylic acid modified product of liquid acrylonitrile-butadiene copolymer, liquid styrene-butadiene copolymer, carboxylic acid modified acrylic polymer as plasticizer component (G And the plasticizer component (G) is easily mixed with the elastomer (B) to improve the printing durability, which is preferable.

  In the photosensitive resin composition, the content of the plasticizer component (G) is preferably 1.0 parts by mass or more and 250 parts by mass or less, more preferably 10 parts by mass with respect to 100 parts by mass of the hydrophilic copolymer (A). The content is not less than 220 parts by mass, and more preferably not less than 20 parts by mass. When the amount is 0.1 parts by mass or more, the cure shrinkage after molding tends to be large, and when the amount is 250 parts by mass or more, the deterioration of cold flow properties tends to be suppressed.

  In addition to the above-described essential or optional components, the photosensitive resin composition for flexographic printing according to this embodiment may further contain various auxiliary additive components as desired, such as thermal polymerization inhibitors, UV absorbers, halations. Inhibitors, light stabilizers and the like can be added.

  In the present embodiment, the photosensitive resin composition for flexographic printing has a structure in which the phase containing the hydrophilic copolymer (A) is separated from the other phase, and specifically, at least a part thereof is Preferably, the phase containing the hydrophilic copolymer (A) has an island structure, and the other phase has a sea-like structure such as a so-called sea-island structure. By using the coupling material (E), the structure of the sea and the island is integrated, and the wear resistance is improved. On the other hand, the washing starts with the phase containing the hydrophilic copolymer (A) as the starting point. When a carboxylic acid modified polymer is used, it can be easily dispersed in the hydrophilic copolymer (A), whereby the degree of hydrophilicity of the phase containing the hydrophilic copolymer (A) in the resin composition becomes high, and this makes it possible to wash the resin composition. It is estimated that sex will increase. However, the factors that improve the abrasion resistance (press resistance), the cleaning property, etc. are not limited to this estimation.

  In the present embodiment, the method of producing the photosensitive resin composition for flexographic printing is not limited.

  For example, when the hydrophilic copolymer (A) is obtained in the form of an aqueous dispersion (latex), it is preferable to use after removing water by various methods. For example, after coagulating the hydrophilic copolymer (A) using an aggregating agent such as sulfate, nitrate, hydrochloride, carbonate, carboxylate and the like, the hydrophilic copolymer ( A) A certain amount of water may be removed from the aqueous dispersion, and then, if necessary, it may be mixed with a plasticizer component (G), a compound (F) such as a surfactant, a stabilizer, etc. and then dried. After mixing with a plasticizer component (G), a compound (F) such as a surfactant, a stabilizer, etc. as required, water is removed from the hydrophilic copolymer (A) -containing aqueous dispersion by distillation or the like May be

  After mixing the hydrophilic copolymer (A) -containing aqueous dispersion with a compound (F) such as a coupling agent (E), a plasticizer component (G), a surfactant, etc. and a stabilizer, etc. Uniformly remove the coupling agent (E), the plasticizer component (G), the compound (F) such as surfactant, and the stabilizer in the hydrophilic copolymer (A). It is preferable because it does not cause a difference in physical properties at the time of image formation when it is used as a printing plate.

  As a method of removing water by distillation or the like, a batch type drier such as a kneader, Nauta mixer, Ribocorn or the like may be used, or a degassing extruder, a thin film distiller, a CD drier, a KRC kneader, an SC processor etc A dryer may be used.

  Thus, the hydrophilic copolymer (A) or the hydrophilic copolymer (A), the plasticizer component (G) added as necessary, the compound (F) such as surfactant, and the like After obtaining a dried product of at least one or more of a mixture of stabilizers and the like, an extruder, a Banbury mixer, together with the elastomer (B), the polymerizable unsaturated monomer (C) and the photopolymerization initiator (D), The photosensitive resin composition can be prepared by kneading using a known kneader such as a kneader.

  In the present embodiment, in order to increase the washability of the photosensitive resin composition for flexographic printing, when using an extruder at the time of resin composition kneading, when using a batch-type kneader, using a screw pattern or screw rotation number. Control the number of rotations and the kneading time, etc. to adjust the degree of kneading, or add the coupling material (E) and the plasticizer component (F) to the hydrophilic copolymer (A) in advance When the hydrophilic copolymer (A) is supplied in the form of an aqueous dispersion by mixing it with the components, the hydrophilic co-polymer (A) can be controlled by controlling the amount of water remaining in the hydrophilic copolymer (A). It is preferable to control the dispersion state of the phase containing the polymer (A).

[Method of producing photosensitive resin composition for flexographic printing plate]
The manufacturing method of the photosensitive resin composition for flexographic printing plates of this embodiment can include the process as described in this order in this order.
To the aqueous dispersion containing the hydrophilic copolymer (A), a coupling agent (E) containing a polymerizable bonding group, the above-mentioned compound (F), and / or a plasticizer component (G) are added Step of removing water from the aqueous dispersion containing the hydrophilic copolymer (A) to obtain a mixture containing the hydrophilic copolymer (A) To a mixture containing the hydrophilic copolymer (A), Process of adding elastomer (B), polymerizable unsaturated monomer (C), and photopolymerization initiator (D)

[Flexographic printing original plate]
In the present embodiment, the flexographic printing original plate has at least a photosensitive layer comprising the photosensitive resin composition of the present embodiment or including the photosensitive resin composition. The photosensitive layer can be formed, for example, by forming the photosensitive resin composition into a layer having a desired thickness by heat press molding, calendering, extrusion, or the like.

  The flexographic printing plate precursor may be a laminate in which a photosensitive layer is provided on a support such as polyester in order to maintain the accuracy as a printing plate.

  In addition, on the surface of the photosensitive layer opposite to the support, in order to improve the contact with the infrared ablation layer or the negative film for drawing directly on the photosensitive layer, and to make it possible to reuse the negative film. A water-based developable flexible film layer (also referred to as a transparent image carrier layer or an antiadhesive layer) may be provided.

  The support, the infrared ablation layer, and the flexible film layer can be brought into close contact with the photosensitive layer by roll lamination, for example, after the photosensitive layer is formed into a sheet. After lamination, heat pressing may be further performed to improve the surface accuracy of the photosensitive layer.

  In this embodiment, as an actinic ray source used for photocuring (forming a latent image) the photosensitive layer of the flexographic printing original plate, for example, a low pressure mercury lamp, a high pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, a xenon lamp, A zirconium lamp, sunlight, etc. are mentioned.

  In this embodiment, after the photosensitive layer is irradiated with light through the infrared ablation layer or the transparent image carrier after drawing to form a latent image, a non-irradiated portion is removed (developed) using a water-based developing solution (relief ( Printing plate) is obtained.

  The aqueous developer is a developer mainly composed of water, and may be water itself, for example, a surfactant such as nonionic or anionic in water, and, if necessary, a pH adjuster, It may be one formulated with a cleaning accelerator or the like.

  Specific examples of the nonionic surfactant include polyoxyalkylene alkyl or alkenyl ether, polyoxyalkylene alkyl or alkenyl phenyl ether, polyoxyalkylene alkyl or alkenyl amine, polyoxyalkylene alkyl or alkenyl amide, ethylene oxide / propylene oxide Block attachments etc. are mentioned.

  Specific examples of the anionic surfactant include, but are not particularly limited to, linear alkyl benzene sulfonate having alkyl having an average of 8 to 16 carbon atoms, α-olefin sulfonate having an average of 10 to 20 carbon atoms, alkyl Dialkyl sulfosuccinate having 4 to 10 carbon atoms of the group or alkenyl group, sulfonate of fatty acid lower alkyl ester, alkyl sulfate having an average of 10 to 20 carbon atoms, linear or branched having an average carbon number of 10 to 20 Examples thereof include alkyl ether sulfates having an alkyl group or alkenyl group and having an average of 0.5 to 8 moles of ethylene oxide added thereto, saturated or unsaturated fatty acid salts having an average carbon number of 10 to 22, and the like.

  The pH adjuster is not particularly limited, and examples thereof include sodium borate, sodium carbonate, sodium silicate, sodium metasilicate, sodium succinate, sodium acetate and the like. Sodium silicate is preferred because it is easily dissolved in water.

  Furthermore, a washing aid may be added to the developer. The cleaning aid means one that enhances the cleaning (developing) ability of the developer by being used in combination with the above-mentioned surfactant and pH adjuster. Specific examples thereof include, but are not particularly limited to, amines such as monoethanolamine, diethanolamine and triethanolamine, ammonium salts such as tetramethylammonium hydroxide, and paraffin hydrocarbons.

  These can be used by, for example, being mixed and mixed with the developer in the range of 0.1 to 50% by mass, preferably 1 to 10% by mass.

  At the time of development, the printing base plate may be vibrated by ultrasonic waves or the like, or the surface of the printing base plate may be rubbed using mechanical means such as a brush.

The developed printing plate is preferably dried, for example, at 50 ° C. for 10 to 120 minutes in an oven.
Depending on the composition of the photosensitive layer containing the photosensitive resin composition of the present embodiment, stickiness may remain on the plate surface even after drying. In that case, stickiness can be removed by a known surface treatment method. As such a surface treatment method, exposure treatment with an actinic ray having a wavelength of 300 nm or less is desirable.

  EXAMPLES The present invention will be specifically described below by way of Examples, but the present invention is not limited thereto.

Production Example 1: Synthesis of Hydrophilic Copolymer (A) -Containing Mixture Containing Other Plasticizer (G)>
In a pressure-resistant reaction vessel equipped with a stirrer and a temperature control jacket, 125 parts by mass of water and (α-sulfo (1-nonylphenoxy) methyl-2- (2-propenyloxy) ethoxy-poly (oxy) as a reactive emulsifier 2 parts by mass of an ammonium salt of "1,2-ethanediyl)" Adekaria soap "(manufactured by Asahi Denka Kogyo Co., Ltd.) is initially charged, the internal temperature is raised to 80 ° C, 10 parts by mass of styrene, 60 parts by mass of butadiene, butyl An oily mixed solution of a monomer mixture consisting of 23 parts by mass of acrylate, 5 parts by mass of methacrylic acid and 2 parts by mass of acrylic acid and 2 parts by mass of t-dodecyl mercaptan, 28 parts by mass of water, sodium peroxodisulfate 1. 2 parts by mass, 0.2 parts by mass of sodium hydroxide, and (α-sulfo (1-nonylphenoxy) methyl-2- (2-propenyloxy) An aqueous solution consisting of 2 parts by weight of the ammonium salt of toxi-poly (oxy-1,2-ethanediyl) was added at a constant flow rate over 5 hours and 6 hours, respectively.

  Then, the temperature of 80 ° C. was maintained for 1 hour to complete the polymerization reaction and then cooled. Furthermore, after adjusting the pH of the resulting copolymer latex to 7 with sodium hydroxide, unreacted monomers are removed by a steam stripping method, and the resultant is filtered through a 200-mesh wire mesh, and finally, the filtrate is solidified. The component concentration was adjusted to 40% by mass to obtain an aqueous dispersion of a hydrophilic copolymer (A).

  In addition, 5 parts by mass of 3-methacryloxypropyltrimethoxysilane [KBM 305: Shin-Etsu Chemical Co., Ltd.] as a coupling material (E) relative to 100 parts by mass of the hydrophilic copolymer (A) contained in the aqueous dispersion. Dried under reduced pressure at 80 ° C. while mixing 10 parts by mass of liquid polybutadiene [LBR 352: manufactured by Kuraray] as a plasticizer component (G), and a hydrophilic copolymer (A) having a coupling material structure and a plasticizer component (G The resulting mixture was dried.

Production Example 2: Preparation of Infrared Ablation Layer
Ethylene-acrylic acid copolymer [SG-2000: made by Lead City, 20% by mass aqueous solution] which is an anionic polymer having a carboxylic acid group as an anionic polar functional group 10 parts by mass, carbon black [BONJET CW-2: Orient Chemical industry, 20 mass% aqueous solution] 5 parts by mass, mold release agent [KF-351: Shin-Etsu Chemical Co., Ltd.] 0.05 parts by mass, water 30 parts by mass and ethanol 15 parts by mass are mixed to form an ablation layer The coating solution of

  The coating solution for forming the ablation layer is coated on a PET film having a thickness of about 100 μm to be a cover film so that the film thickness after drying becomes 3 μm, and subjected to a drying treatment at 90 ° C. for 2 minutes. A laminate of the ablation layer and the cover film was obtained.

Example 1
(1) Production of Photosensitive Resin Composition 110 parts by mass of a mixture containing the hydrophilic copolymer (A) having a coupling material structure obtained in Production Example 1 and another plasticizer component (G), an elastomer ( B): Styrene-butadiene-styrene copolymer [D-KX 405: made by Kraton] 75 parts by mass, after mixing at 140 ° C. using a pressure kneader, 40 parts by mass of liquid polybutadiene [LBR-352 made by Kuraray], polymerization Unsaturated monomer (C): 10 parts by mass of 1,9-nonanediol diacrylate and 10 parts by mass of 1,6-hexanediol dimethacrylate, photopolymerization initiator (D): 2,2-dimethoxyphenylacetophenone 5 Parts by weight, surfactant (F): 2 parts by weight of [NT-12: Dai-ichi Kogyo Seiyaku], and 5 parts by weight of 2,6-di-t-butyl-p-cresol as a stabilizer The compound was added gradually over 15 minutes, and after addition, the mixture was further kneaded for 20 minutes to obtain a photosensitive resin composition.

(2) Production of printing base plate The above composition was taken out, and a thickness of 100 μm thick polyester film (hereinafter abbreviated as PET) coated with an elastomer-containing adhesive and a thickness of 5 μm thick polyvinyl alcohol (PVA) layer coated Sandwiched between 100 μm PET and molded into a plate having a thickness of 1.14 mm using a press heated to 120 ° C., followed by peeling off the PET coated with the PVA layer, support (PET)- A laminate comprising a photosensitive layer was obtained. The infrared ablation layer obtained in Production Example 2 was laminated on the obtained laminate so as to be in contact with the photosensitive layer, to obtain a printing original plate.

(3) Production of printing plate A UV exposure machine (Nippon Denshi Co., Ltd.) so that the pattern height (RD) after curing becomes about 0.6 mm from the side of the support (PET coated with adhesive) of the printing original plate It exposed using Seiki Co., Ltd. product JE-A2-SS.

  Next, the cover film of the infrared ablation layer was peeled off and drawn on the infrared ablation layer using a laser drawing machine (CDI made by ESKO), and then exposed for 10 minutes from the side of the infrared ablation layer by the above-mentioned ultraviolet exposure device.

  After exposure, an aqueous solution (water-based developer) of 1% Nissan soap was prepared and washed (developed) at 40 ° C. using a Nihon Electronics Seiki washer (JOW-A3-P) to remove the unexposed area. . As for the cleaning time, the thickness d (mm) of the unexposed printing original plate is washed in advance for 5 minutes and scraped off, and the thickness d (mm) is measured to match the desired pattern height (RD = 0.6 (mm)). , RD × d × 1.5 (minutes) was calculated and taken as that time. After drying, the plate was post-exposed with an ultraviolet sterilization lamp and an ultraviolet chemical lamp to obtain a printing plate.

(4) Evaluation (a) Evaluation of the washability (water developability) of the printing base plate A 1% aqueous solution of Nissan soap was filled in a washing machine (JOW-A3-P) manufactured by Nippon Denshi Seiki Co., Ltd., and the printing obtained in (2) The cover film of the original infrared ablation layer was peeled off and washed at 40 ° C. for 5 minutes.

  The case where scraped by 0.5 mm or more is ◎, the case of scraped by 0.3 mm or more and less than 0.5 mm is marked by ○, 0.1 mm or more and less than 0.3 mm by 、, and the scraped amount is less than 0.1 mm by x.

(B) Evaluation of printing durability of printing plate In order to evaluate the plate surface strength (printing durability) of the printing plate, using a wear wheel (a taper wear tester made by tester industry, hard wear wheel) in a pseudo manner The abrasion test was done.

A printing plate of the entire solid part is prepared in the same manner as (2), and the obtained printing plate is immersed in a 10% aqueous isopropyl alcohol solution for 16 hours as a water-based ink substitute, and then after 1000 rotations using a wear ring. The amount of abrasion of the printing plate (mg / cm ² ) was measured. The amount of wear was determined by dividing the decrease in mass of the printing plate (mg) by the area (cm ² ) at which the wear wheel comes in contact with the solid portion.

The abrasion loss was less than 2 mg / cm ² as ◎, 2 mg / cm ² or more and 5 mg / cm ² as を, and 5 mg / cm ² or more as x.

(C) Evaluation of transparency (Haze) of the printing original plate The photosensitive resin composition was molded into a plate of 3 mm thickness by a press heated to 120 ° C. with a 100 μm-thick PET film subjected to mold release treatment on both sides.

  Using a haze meter (NDH-5000) manufactured by Nippon Denshoku Kogyo Co., Ltd., the haze of a plate molded to a thickness of 3 mm in an uncured state was measured. A haze of 20 or less was evaluated as ○, 20 to 30 or less as Δ, and 30 to 50 or more as x.

(D) Evaluation of image reproducibility (water swellability) before and after moisture absorption The photosensitive resin printing plate prepared in (3) and the printing base plate prepared in (2) are stored for one week in a thermostatic chamber at 40 ° C. and 80% humidity. A printing plate was produced in the same manner as in (3). The white line width and depth of 500 μm were compared before and after moisture absorption. When the difference between the line width and the depth after moisture absorption is less than 5%, ○, when 5% or more and less than 10%,%, and 10% or more is x.

(Example 2-7, Comparative Example 1)
A photosensitive resin composition, an original plate for flexographic printing comprising the resin composition, and a printing in the same manner as in Example 1 except that the type and addition amount of the coupling material (E) are changed as shown in Table 1. I got the version. The evaluation results of the obtained photosensitive resin composition, printing base plate and printing plate are shown in Table 2.

(Comparative example 2)
A photosensitive resin was obtained in the same manner as in Example 1 except that the coupling material (E) was not used. The evaluation results of the obtained photosensitive resin composition, printing base plate and printing plate are shown in Table 2.

  The resin composition for flexographic printing of the present invention can be suitably used as a material of a photosensitive layer of a flexographic printing original plate, particularly a flexographic printing original plate for water-based development.

Claims (9)

At least a hydrophilic copolymer (A), an elastomer (B), a polymerizable unsaturated monomer (C), and a photopolymerization initiator,
The hydrophilic copolymer (A) has a structure derived from a coupling material (E),
Photosensitive resin composition for flexographic printing plates. The coupling material (E) is a compound represented by formula (I) or formula (II):
The photosensitive resin composition for flexographic printing plates of Claim 1.
X _3-n (CH ₃ ) _n -Si- (CH ₂ ) _m -Y ... (I)
(In the formula, X represents a hydrolyzable group, Y represents an organic functional group, n represents 0, 1 or 2, and m represents 1 to 6.)
Y-(CH ₂ ) _m- Y ..... (II)
[In formula, Y shows an organic functional group and m shows 1-6. ] The hydrolyzable group X in the formula (I) is at least one selected from the group consisting of a methoxy group (CH ₃ O—) and an ethoxy group (CH ₃ CH ₂ O—),
Formula (II) an organic functional group Y in is amino (-NH _2), a vinyl group (-CH = CH _2), acryloxy group (-OOCCH = CH _2), methacryloxy group (-OOCC (CH ₃₎ = CH ₂ ), isocyanate group (-N = C = O), mercapto group (-SH), sulfur atom (-S-), ureido group (-NHCONH ₂ ), oxetanyl group, and epoxy group (-C- ( And at least one selected from the group consisting of -O-)-C-),
The photosensitive resin composition for flexographic printing plates of Claim 2. 30 parts by mass or more and 250 parts by mass or less of the elastomer (B) and 10 parts by mass or more and 200 parts by mass of the polymerizable unsaturated monomer (C) with respect to 100 parts by mass of the hydrophilic copolymer (A) The photopolymerization initiator (D) is contained in an amount of 0.1 parts by mass or more and 50 parts by mass or less.
The photosensitive resin composition for flexographic printing plates as described in any one of Claims 1-3. At least one selected from the group consisting of surfactants, (meth) acrylic acid ester monomers having polyalkylene glycol chains, and compounds having an acid value of 10 mg KOH / g to less than 400 mg KOH / g and containing a carboxylic acid structure. 0.1 to 15 parts by mass of the compound (F) is further contained,
The photosensitive resin composition for flexographic printing plates as described in any one of Claims 1-4. The plasticizer component (G) is further contained in an amount of 1.0 to 250 parts by mass with respect to 100 parts by mass of the hydrophilic copolymer (A).
The photosensitive resin composition for flexographic printing plates as described in any one of Claims 1-5. The hydrophilic copolymer (A) is an internally crosslinked polymer particle comprising a unit derived from a reactive emulsifier containing an unsaturated double bond,
The photosensitive resin composition for flexographic printing plates as described in any one of Claims 1-6. It is a manufacturing method of the photosensitive resin composition for flexographic printing plates as described in any one of Claims 1-7,
Coupling agent (E) containing a polymerizable bonding group, surfactant, (meth) acrylic acid ester monomer having polyalkylene glycol chain in aqueous dispersion containing hydrophilic copolymer (A) A step of adding at least one compound (F) selected from the group consisting of a compound having an acid value of 10 mg KOH / g to less than 400 mg KOH / g and containing a carboxylic acid, and / or a plasticizer component (G)
Water is removed from the aqueous dispersion containing the hydrophilic copolymer (A) to obtain a mixture containing the hydrophilic copolymer (A), and a mixture containing the hydrophilic copolymer (A) And (e) adding an elastomer (B), a polymerizable unsaturated monomer (C), and a photopolymerization initiator (D). It has a photosensitive layer containing the photosensitive resin composition for flexographic printing plates as described in any one of Claims 1 to 7,
Flexographic printing original plate.