JP2019066602A - Flexographic printing plate - Google Patents

Abstract

To provide a method for preventing a flexographic printing plate from peeling from an adhesive base material such as a cushion tape.SOLUTION: A flexographic printing plate has a photosensitive resin layer laminated on at least a support film. The flexographic printing plate material before photopolymerization shows a flexure elastic modulus of 20 gf/inch or more, and shows a flexure elastic modulus of 100 gf/inch or less after the photopolymerization.SELECTED DRAWING: None

Description

  The present invention relates to flexographic printing plates.

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.
When printing using a flexographic printing plate, the flexographic printing plate is attached to the cylinder of the printing press, but in order to make the plate change efficient, the flexographic printing plate is not directly attached to the cylinder but the flexographic printing plate It may be stuck to a sleeve and such a sleeve may be attached to a cylinder. As a method of producing a sleeve for mounting a flexographic printing plate on a printing press, a cushion tape is attached to the sleeve, and a cushioning tape is attached to the flexographic printing plate on which a photosensitive resin layer formed and cured is formed on a support film. There is a method of sticking on a predetermined position on the sleeve (for example, Patent Document 1).

  Moreover, as a method of mounting a printing plate, when winding a printing original layer sheet around a cylindrical support, a method of winding and welding so that the winding start and end of the sheet overlap (for example, Patent Document 2), a support There is also a method of providing an adhesive layer on at least a part of the back surface opposite to the surface on which the relief layer or the relief forming layer is formed (for example, Patent Document 3).

International Publication No. 2000/39640 JP, 2010-076243, A JP, 2016-210104, A

Since the flexographic printing plate is printed by being stuck in a predetermined position via the adhesive tape on the printing sleeve, from the edge portion stuck on the sleeve during printing, between the adhesive tape and the flexographic printing plate Ink, detergents and the like may intrude and the adhesive strength may be reduced to cause peeling.
In recent years, the printing speed of flexo printing has been increased to improve printing efficiency. An increase in printing speed may load the flexographic printing plate on the sleeve and may peel off the end of the flexographic printing plate attached to the cushion tape. Since the printing must be interrupted by peeling off the edge of the flexographic printing plate, flexibility of the flexographic printing plate is required to prevent peeling of the interface between the cushion tape and the printing plate.
Furthermore, since the flexographic printing plate material in the process of producing the flexographic printing plate is transported between manufacturing devices etc. in a flat state and a load is applied to the flexographic printing plate material, the flexographic printing plate material is required to have a rigidity that resists bending. It is done.

  That is, it is an object of the present invention to provide a method for preventing flexo printing plate material from bending easily, that is, having rigidity and preventing flexo printing plate from peeling off from an adhesive base material such as a cushion tape.

MEANS TO SOLVE THE PROBLEM As a result of earnest research in order to solve the said subject, the present inventors have a flexo printing plate which has a bending elastic modulus of a specific range from the base material which flexo printing plate material has rigidity and has adhesiveness. It has been found that it is difficult to peel off, and the present invention has been completed.
That is, the present invention is as follows.

[1]
A flexographic printing plate in which a photosensitive resin layer is laminated on at least a support film,
The flexural modulus of the flexographic printing plate material before photopolymerization is 20 gf / inch or more, and
A flexographic printing plate, wherein the flexural modulus of the flexographic printing plate after photopolymerization is 100 gf / inch or less.
[2]
The photosensitive resin layer comprises a photosensitive resin composition containing a thermoplastic elastomer (a) and a photopolymerizable monomer (c),
The multiplicative value of the mass percent concentration of the thermoplastic elastomer (a) and the mass percent concentration of the photopolymerizable monomer (c) in the photosensitive resin composition is not less than 0.030 and less than 0.070, [1] Flexographic printing plate as described.
[3]
The flexographic printing plate as described in [1] or [2] whose thickness is 2.0 mm or less.
[4]
The flexographic printing plate according to any one of [1] to [3], wherein the thickness of the support film is 100 μm or more and 200 μm or less.
[5]
The flexographic printing plate according to any one of [1] to [4], wherein the support film is polyethylene terephthalate.
[6]
The flexographic printing plate according to any one of [1] to [5], having a primer-treated layer on the surface opposite to the surface on which the photosensitive resin layer of the support film is laminated.
[7]
The flexographic printing plate according to [6], wherein the thickness of the primer-treated layer is 0.1 g / m ² or more and 30 g / m ² or less.
[8]
The flexographic printing plate according to [6] or [7], wherein a plastic material soluble in an organic solvent is used to form the primer treatment layer.

  According to the present invention, it is possible to provide a flexographic printing plate which has rigidity in the process of producing the flexographic printing plate and prevents the flexographic printing plate from peeling off from an adhesive substrate such as a cushion tape.

It is a figure explaining the evaluation method of the rigidity of flexographic printing plate material.

  Hereinafter, the mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in more detail, but the present invention is not limited to this, and various modifications can be made within the scope of the present invention. Variations are possible.

[Flexographic printing plate]
The flexographic printing plate of the present embodiment is a flexographic printing plate in which a photosensitive resin layer is laminated on at least a support film.
Further, in the flexographic printing plate of the present embodiment, the flexural modulus of the flexographic printing plate material before photopolymerization is 20 gf / inch or more, and the flexural modulus of the flexographic printing plate after photopolymerization is 100 gf / inch. It is below.

The flexographic printing plate of the present embodiment is one in which a support film and a photosensitive resin layer are integrated, and the photosensitive resin layer and the support film in the flexographic printing plate are integrated, for example, through an adhesive layer. Be Moreover, the flexographic printing plate after photopolymerization in this embodiment is a flexographic printing plate in the state after the photosensitive resin layer was hardened | cured by photopolymerization.
The flexographic printing plate material in the present embodiment is a flexographic printing plate in a state before the photosensitive resin layer is cured by photopolymerization.

The thickness of the flexographic printing plate of the present embodiment is preferably 3.0 mm or less, more preferably 2.0 mm or less, and still more preferably 1.7 mm or less. When the thickness of the flexographic printing plate is 2.0 mm or less, the occurrence of edge lift tends to be suppressed.
The lower limit of the thickness of the flexographic printing plate of the present embodiment is usually 0.5 mm or more. When the thickness of the flexographic printing plate is 0.5 mm or more, the rigidity of the flexographic printing plate material tends to be secured.
The thickness of the flexographic printing plate of the present embodiment can be controlled, for example, by adjusting the thickness of the support film or the lamination amount of the photosensitive resin layer.
The thickness of the flexographic printing plate of this embodiment can be specifically measured by the method described in the examples.

The support film in the present embodiment preferably has a thickness of 200 μm or less. By setting the thickness of the support film to 200 μm or less, the occurrence of peeling of the flexographic printing plate from the adhesive substrate, that is, the occurrence of edge lift tends to be suppressed.
The thickness of the support film is preferably 100 μm or more, more preferably 125 μm or more, from the viewpoint of stably forming the flexographic printing plate from the flexographic printing plate material.

  The support film is not particularly limited, and examples thereof include polypropylene films, polyethylene films, polyester films such as polyethylene terephthalate and polyethylene naphthalate, and polyamide films. Among these support films, preferred is polyethylene terephthalate.

As a method of setting the thickness of the support film to 100 μm or more and 200 μm or less, a film having a thickness of 100 μm or more and 200 μm or less may be selected.
Specifically, the thickness of the support film can be measured by the method described in the examples.

In the flexographic printing plate of the present embodiment, the flexural modulus of the flexographic printing plate material before photopolymerization is 20 gf / inch or more, and the flexural modulus of the flexographic printing plate after photopolymerization is 100 gf / inch or less.
By setting the flexural modulus of the flexographic printing plate after photopolymerization to 100 gf / inch or less, the occurrence of edge lift can be suppressed. The flexural modulus of the flexographic printing plate after photopolymerization is preferably 80 gf / inch or less, more preferably 60 gf / inch or less.
The lower limit of the flexural modulus of the flexographic printing plate after photopolymerization is usually 30 gf / inch or more.

By setting the flexural modulus of the flexographic printing plate material before photopolymerization to 20 gf / inch or more, it is possible to transfer between manufacturing devices in a flat state without bending in the process of producing the flexographic printing plate. The flexural modulus before photopolymerization of the flexographic printing plate is preferably 25 gf / inch or more, more preferably 30 gf / inch or more.
The upper limit of the flexural modulus of the flexographic printing plate material before photopolymerization is usually 100 gf / inch or less.

Flexural modulus of the flexographic printing plate material and the flexographic printing plate is determined by the ratio of the amount of the thermoplastic elastomer in the resin composition and / or the amount of the hydrophilic copolymer and the amount of the photopolymerizable monomer, the thickness of the photosensitive resin layer and the support film It can be adjusted by
For example, when the amount of the thermoplastic elastomer is increased, the flexural modulus tends to be increased, and by replacing the thermoplastic elastomer with the hydrophilic copolymer, the flexural modulus tends to be reduced. In addition, when the resin thickness and the support thickness are increased, the flexural modulus tends to increase, and when the resin thickness and the support thickness are reduced, the flexural modulus tends to decrease.
The flexural modulus of the flexographic printing plate material and the flexographic printing plate can be measured specifically by the method described in the examples.

  The flexographic printing plate of the present embodiment is obtained by making a flexographic printing original plate in which a photosensitive resin layer is laminated on at least a support film by plate making such as back exposure, relief exposure, removal of unexposed portions, post-treatment exposure described later. It is preferable that it is a flexographic printing plate. The flexographic printing plate of this embodiment is preferably derived from the above flexographic printing plate precursor.

<Photosensitive resin layer>
The photosensitive resin layer in the flexographic printing plate of the present embodiment is formed by laminating a photosensitive resin composition on a support film.
Examples of the photosensitive resin composition include (a) a thermoplastic elastomer and / or (b) a hydrophilic copolymer, (c) a photopolymerizable monomer, and a photosensitive resin composition containing a photopolymerization initiator. be able to. The photosensitive resin layer in the flexographic printing plate of the present embodiment preferably contains (a) a thermoplastic elastomer and / or (b) a hydrophilic copolymer, (c) a photopolymerizable monomer, and a photopolymerization initiator. In particular, when the removal of the unexposed part is carried out in an aqueous washing solution, the photosensitive resin composition preferably contains (b) a hydrophilic copolymer.
The photosensitive resin composition in the present embodiment includes (a) a thermoplastic elastomer, (b) a hydrophilic copolymer, a liquid rubber component, (c) a photopolymerizable monomer, and a photocurable resin composition containing a photopolymerization initiator. And a photocurable resin composition comprising (a) a thermoplastic elastomer, (c) a photopolymerizable monomer, and a photopolymerization initiator.

The multiplicative value of the mass percent concentration of the thermoplastic elastomer (a) and the mass percent concentration of the photopolymerizable monomer (c) in the photosensitive composition described above is preferably 0.030 or more and less than 0.070.
By setting the multiplication value to 0.030 or more and less than 0.070, the flexural modulus of the flexographic printing plate after photopolymerization tends to be able to be adjusted to 100 gf / inch or less.
The multiplication value is more preferably 0.035 or more and less than 0.065, and still more preferably 0.037 or more and less than 0.063.

((A) Thermoplastic elastomer)
As the thermoplastic elastomer (a), a thermoplastic elastomer containing at least one polymer block mainly composed of conjugated diene and at least one polymer block mainly composed of vinyl aromatic hydrocarbon is preferable.

  The term "based on" as used throughout this specification means greater than 60 wt% in the polymer block. The conjugated diene is preferably 80 wt% or more in the polymer block, and more preferably 90 wt% or more.

  As a conjugated diene, for example, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1 Examples thereof include monomers of 2,3-octadiene, 3-butyl-1,3-octadiene, and chloroprene, and among these, 1,3-butadiene is preferable from the viewpoint of abrasion resistance. These monomers may be used alone or in combination of two or more. The vinyl content in the total butadiene of the polymer block mainly composed of conjugated diene, for example, the content of 1,2-butadiene and 3,4-isoprene is not particularly limited. From the viewpoint of plate formation, the vinyl content is preferably 5 mol% to 50 mol%, more preferably 8 mol% to 50 mol%, and still more preferably 10 mol% to 40 mol%.

  From the viewpoint of printing durability, the number average molecular weight of the polymer block mainly composed of conjugated diene is preferably 20,000 to 250,000, more preferably 30,000 to 20,000, and 40,000 to 150,000. Is more preferred.

  Polymer blocks based on conjugated dienes may contain alkylene units. The method for introducing the alkylene unit is not particularly limited, but a method of polymerizing a monoolefin such as ethylene or butylene to a raw material monomer of a polymer block mainly composed of a conjugated diene or a method of hydrogenating a conjugated diene polymer block may be mentioned. . Among these, from the viewpoint of availability, hydrogenation of a polymer block composed mainly of a conjugated diene is preferable. The content of the alkylene unit in the polymer block mainly composed of a conjugated diene is preferably 5 mol% or more from the viewpoint of solvent resistance and 50 mol% or less from the viewpoint of securing the transparency of the resin composition. The range of 10 mol% to 35 mol% is more preferable, and the range of 10 mol% to 25 mol% is more preferable.

  The above-mentioned alkylene units are preferably contained in a polymer block mainly composed of butadiene. Preferably, the butadiene-based polymer block is hydrogenated to contain all 1,4-butadiene units, 1,2-butadiene (vinyl) units and butylene (alkylene) units. More preferable. More preferably, at least 25 mol% to 70 mol% of 1,4-butadiene units, 0 mol% to 50 mol% of butadiene units, and at least 25 mol% to 70 mol% of 1,4-butadiene units in a butadiene-based polymer block However, the range of 10 mol% to 50 mol% is preferable.

The content and ratio of the conjugated diene, the vinyl content of the conjugated diene and vinyl aromatic hydrocarbon can be measured using a nuclear magnetic resonance apparatus ⁽¹ H-NMR).

  Examples of vinyl aromatic hydrocarbons include styrene, t-butylstyrene, divinylbenzene, 1,1-diphenylstyrene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, Monomers such as vinylpyridine, p-methylstyrene, tertiary butylstyrene, α-methylstyrene, 1,1-diphenylethylene and the like can be mentioned. Among them, the photosensitive resin composition can be molded smoothly at a relatively low temperature. (Hereinafter referred to as high moldability), styrene is preferred. These monomers may be used alone or in combination of two or more.

  The number average molecular weight of the polymer block mainly composed of vinyl aromatic hydrocarbon is preferably 100,000 or less in order not to give orientation to the printing plate, and from the viewpoint of chipping resistance at the time of plate making or printing, 0.3 10,000 or more is preferable. The range of 50,000 to 80,000 is more preferable, and the range of 50,000 to 60,000 is more preferable.

  The content of the vinyl aromatic hydrocarbon in the block copolymer maintains the printing plate hardness high when the high moldability of the photosensitive resin composition, the high scuff resistance of the convex portion of the printing plate, and the ink component adhere Therefore, it is preferable to make it 25 wt% or less. On the other hand, 13 wt% or more is preferable in that the cold flow resistance of the photosensitive resin composition is high. The range of 15 wt% to 24 wt% is more preferable, and the range of 16 wt% to 23 wt% is more preferable.

  The polymer block mainly composed of a conjugated diene may contain a block of the third component, if necessary.

  The number average molecular weight of the conjugated diene-based polymer block is preferably greater than 20,000, and more preferably 230,000 or more.

The content of the thermoplastic elastomer (a) in the photosensitive resin layer is preferably 15 wt% to 90 wt%, when the total amount of the photosensitive resin composition is 100 wt%, from the viewpoint of printing durability at the time of printing . The content of the thermoplastic elastomer (a) is more preferably 15 wt% to 80 wt%, and still more preferably 20 wt% to 75 wt%.
When the light resin composition in this embodiment contains (b) a hydrophilic copolymer, the total content of (a) the thermoplastic elastomer and (b) the hydrophilic copolymer in the photosensitive resin layer is photosensitive. When the total amount of the resin composition is 100 wt%, it is preferably 40 wt% to 75 wt%, more preferably 45 wt% to 65 wt%, and still more preferably 50 wt% to 60 wt%.
When the photosensitive resin composition in the present embodiment does not contain (b) a hydrophilic copolymer, the content of the (a) thermoplastic elastomer in the photosensitive resin layer is 100 wt% of the total amount of the photosensitive resin composition. When it has, it is preferable that it is 40 wt%-75 wt%, It is more preferable that it is 45 wt%-65 wt%, It is more preferable that it is 50 wt%-60 wt%.

((B) hydrophilic copolymer)
(B) The hydrophilic copolymer is an internally crosslinked polymer particle containing a unit derived from a hydrophilic unsaturated monomer. As the above-mentioned polymer particles, for example, dispersoids obtained by emulsion polymerization of polymer particles obtained by using a hydrophilic unsaturated monomer and, if necessary, another monomer copolymerizable therewith As the water dispersion latex dispersed in water, those obtained by removing water are mentioned. The unit derived from the hydrophilic unsaturated monomer may be, for example, 0.1 to 20% by mass, or 0.5 to 15% by mass in all the monomers, or 1 to 10%. It may be%.

  As a hydrophilic unsaturated monomer, a monomer containing at least one hydrophilic group and an unsaturated double bond is preferable. As a hydrophilic unsaturated monomer, for example, a carboxylic acid, a sulfonic acid, a phosphoric acid group, etc., and salts thereof, and a single amount containing an unsaturated double bond containing an acid anhydride group etc. A monomer containing a hydroxyl group and an unsaturated double bond; a monomer containing an acrylamide and an unsaturated double bond; a surfactant containing a reactive unsaturated double bond (monomer); Be One of these hydrophilic unsaturated monomers may be used alone, or two or more thereof may be used.

Specific examples of the water-dispersible latex include acrylonitrile-butadiene copolymer latex, polychloroprene latex, polyisoprene latex, polyurethane latex, (meth) acrylate-butadiene latex, vinylpyridine polymer latex, butyl polymer latex, and thiocol. Water-dispersible latex polymers, such as polymer latex and acrylate polymer latex, etc. are mentioned. In these aqueous dispersion latexes, (meth) acrylates, carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, vinylbenzoic acid, cinnamic acid and the like, monobasic acids of sulfonic acids such as styrene sulfonic acid and the like; itaconic acid Preferred are water-dispersible latex polymers obtained by copolymerizing one or more kinds of acid functional group-containing unsaturated monomers such as fumaric acid, maleic acid, dibasic acids such as citraconic acid and muconic acid; and the like.
In addition to the polymer particles obtained by emulsion polymerization using a hydrophilic unsaturated monomer and, if necessary, other monomers copolymerizable therewith, the water dispersion latex is 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 a molecular chain of a polymer 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) acrylic acid ester, acrylic acid, methacrylic acid, itaconic acid, etc. Copolymerized ones are preferred. As the water dispersion latex, more preferably, the styrene-butadiene copolymer is co-polymerized with (meth) acrylic acid ester, or with one or more kinds of acid functional group-containing unsaturated monomers such as acrylic acid, methacrylic acid, itaconic acid, etc. It is an aqueous dispersion latex of a polymerized copolymer.

  It is preferable that the usage-amount of an acidic functional group containing unsaturated monomer is 1-30 mass% among the unsaturated monomer whole quantity used for the synthesis | combination of (b) hydrophilic copolymer. By making the usage fee 1% by mass or more, aqueous development tends to be facilitated, and by making it 30% by mass or less, the moisture absorption amount of the photosensitive resin composition increases, and the swelling amount of the ink increases. Thus, it is possible to prevent the deterioration of the processability at the time of mixing of the photosensitive resin composition.

  (B) As unsaturated monomers other than the acidic functional group containing unsaturated monomer which can be used for the synthesis of hydrophilic copolymer, conjugated diene, aromatic vinyl compound, (meth) acrylic acid ester, hydroxyl group Ethylenic monocarboxylic acid alkyl ester monomers, unsaturated dibasic acid alkyl esters, maleic anhydride, vinyl cyanide compounds, (meth) acrylamides and derivatives thereof, vinyl esters, vinyl ethers, vinyl halides, Basic monomers having an amino group, vinyl pyridine, olefins, silicon-containing α, β-ethylenically unsaturated monomers, allyl compounds and the like can be mentioned.

Examples of conjugated dienes include 1,3-butadiene, isoprene, 2,3-dimethyl 1,3-butadiene, 2-ethyl-1,3-butadiene, 2-methyl-1,3-butadiene, 1,3- Pentadiene, chloroprene, 2-chloro-1,3-butadiene, cyclopentadiene and the like can be mentioned.
Examples of the aromatic vinyl compound include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ethylstyrene, vinyltoluene, vinylxylene, bromoxylene, vinylbenzyl chloride, p-t -Butylstyrene, chlorostyrene, alkylstyrene, divinylbenzene, trivinylbenzene and the like.

  Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate and 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 (meth) acrylate, Roxycyclohexyl (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 (meth) acrylate Triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) a Lilate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, allyl (meth) acrylate, bis (4-acryloxypolyethoxyphenyl) propane, methoxypolyethylen glycol (Meth) acrylate, β- (meth) acryloyloxyethyl hydrogen phthalate, β- (meth) acryloyloxyethyl hydrogen succinate, 3-chloro-2-hydroxypropyl (meth) acrylate, stearyl (meth) acrylate, phenoxy Ethyl (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, 2-hydroxy-1,3-di (meth) acryloxypropane, 2,2-bis [4 ((Meth) acryloxyethoxy) phenyl] propane, 2,2-bis [4-((meth) acryloxy.diethoxy) phenyl] propane, 2,2-bis [4-((meth) acryloxypolyethoxy) phenyl] Propane, isobornyl (meth) acrylate and the like can be mentioned.

  Examples of ethylenic monocarboxylic acid alkyl ester monomers having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 1-acrylate Hydroxypropyl, 1-hydroxypropyl methacrylate, hydroxycyclohexyl (meth) acrylate and the like can be mentioned.

  Examples of the unsaturated dibasic acid alkyl ester include crotonic acid alkyl ester, itaconic acid alkyl ester, fumaric acid alkyl ester, and maleic acid alkyl ester.

  Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile.

  Examples of (meth) acrylamide and derivatives thereof include (meth) acrylamide, N-methylol (meth) acrylamide, N-alkoxy (meth) acrylamide and the like.

  Examples of the vinyl esters include vinyl acetate, vinyl butyrate, vinyl stearate, vinyl laurate, vinyl myristate, vinyl propionate, vinyl versatate and the like.

  Examples of vinyl ethers include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, amyl vinyl ether, hexyl vinyl ether and the like.

  Examples of halogenated vinyls include vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride and the like.

  Examples of the basic monomer having an amino group include aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate and the like.

  As an olefin, ethylene etc. are mentioned, for example.

  Examples of the silicon-containing α, β-ethylenically unsaturated monomer include vinyltrichlorosilane and vinyltriethoxysilane.

  As the allyl compound, for example, allyl ester, diallyl phthalate and the like can be mentioned. In addition, monomers having three or more double bonds such as triallyl isocyanurate can also be used.

  These monomers may be used alone or in combination of two or more. The mass ratio of the acidic functional group-containing unsaturated monomer to the other monomer is preferably 5/95 to 95/5, more preferably 50/50 to 90/10. When it exceeds 5/95 to 95/5, the rubber elasticity of the photosensitive resin composition for flexographic printing may be deteriorated.

  (B) The hydrophilic copolymer is preferably a polymer synthesized by emulsion polymerization, and in this case, as an emulsifier (surfactant) used at the time of polymerization, a reactive emulsifier is preferable.

  As the reactive emulsifying agent, a reactive emulsifying agent having an emulsifying, dispersing, and wetting function is preferable, as in general emulsifying agents, containing a radically polymerizable double bond, a hydrophilic functional group and a hydrophobic group in the molecular structure. . In addition, when (b) the hydrophilic copolymer is obtained by emulsion polymerization, the reactive emulsifier is preferably 100 parts by mass of the acidic functional group-containing unsaturated monomer excluding the reactive emulsifier and other monomers. An emulsion (surfactant) agent capable of synthesizing a polymer having an average particle diameter of 5 to 500 nm is more preferable when 0.1 part by mass or more is used.

Examples of the structure of the radically polymerizable double bond in the molecular structure of the reactive emulsifier include, for example, a vinyl group, an acryloyl group, or a methacryloyl group.
Examples of the hydrophilic functional group in the molecular structure of the reactive emulsifier include 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 polyoxymethylene and polyoxypropylene; and hydroxyl groups.
As a hydrophobic group in the molecular structure of a reactive emulsifier, an alkyl group, a phenyl group, etc. are mentioned, for example.

  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 contain multiple types.

  The reactive emulsifier may be a commercially available one, and a commercially available anionic surfactant is not particularly limited, and examples thereof include Adekaria Soap SE (manufactured by Asahi Denka Kogyo Co., Ltd.), Aqualon HS, BC, and KH. (Daiichi Kogyo Seiyaku Co., Ltd.), Latemule S (Kao Co., Ltd.), Antox MS (Nippon Emulsifier Co., Ltd.), Adekaria Soap SDX or PP (Asahi Denka Kogyo Co., Ltd.), Haitenor A (Daiichi Kogyo Seiyaku Co., Ltd. And Eminor RS (manufactured by Sanyo Chemical Industries, Ltd.), Spinomer (manufactured by Toyo Soda Co., Ltd.), etc., and commercially available nonionic surfactants are not particularly limited. For example, Aqualon RN or Neugen N can be used. (Made by Dai-ichi Kogyo Seiyaku Co., Ltd.), Adekaria Soap NE (made by Asahi Denka Kogyo Co., Ltd.) and the like. These may be used alone or in combination of two or more.

  The use amount of the reactive emulsifier is preferably in the range of 1 to 20 parts by mass with respect to 100 parts by mass of the (b) hydrophilic copolymer calculated from the preparation amount of the raw material. 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 case of synthesizing the (b) hydrophilic copolymer in the present embodiment by emulsion polymerization, a non-reactive emulsifier can also be used, if necessary.
Examples of the non-reactive emulsifier include anionic surfactants such as fatty acid soap, rosin acid soap, sulfonate, sulfate, phosphate ester, polyphosphate ester, acyl salicylate, etc .; nitrileated oil and fat derivative, oil and fat derivative, Cationic surfactants such as fatty acid derivatives and α-olefin derivatives; Alcohol ethoxylates, alkylphenol ethoxylates, propoxylates, aliphatic alkanolamides, alkyl polyglycosides, polyoxyethylene sorbitan fatty acid esters, nonionics such as oxyethylene oxypropylene block copolymers Surfactants are exemplified. These may be used alone or in combination of two or more.

  As a sulfonate, for example, alkyl sulfonate, alkyl sulfate, alkyl sulfosuccinate, polyoxyethylene alkyl sulfate, sulfonated oil and fat, alkyl diphenyl ether disulfonate, α-olefin sulfonate, alkyl glyceryl ether sulfone Acid salts, N-acylmethyl taurate and the like.

  Other examples of non-reactive emulsifiers 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 (b) hydrophilic copolymers calculated from the preparation amount of a raw material. When the amount of the non-reactive emulsifier used is less than 1 part by mass, the obtained printing plate has an appropriate water swelling rate, so that the abrasion resistance at the time of ink adhesion decreases and the image reproducibility after moisture absorption decreases. It can prevent.

(B) As an emulsion polymerization method of a hydrophilic copolymer, a predetermined amount of water, an emulsifying agent and other additives are charged in advance into a reaction system adjusted to a polymerizable temperature, and a polymerization initiator and an unsaturated monomer are added to this system. It is general to add a monomer, an emulsifier, a modifier and the like into the reaction system by 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 (b) hydrophilic copolymer. As the chain transfer agent, a chain transfer agent containing elemental sulfur can be suitably used. Examples of chain transfer agents containing elemental sulfur include alkanethiols such as t-dodecyl mercaptan and n-dodecyl mercaptan; thioalkyl alcohols such as mercaptoethanol and mercaptopropanol; thioalkyl carbons such as thioglycolic acid and thiopropionic acid Thiocarboxylic acid alkyl esters such as acid; 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 can include halogenated hydrocarbons such as terpinorene, dipentene, t-terpinene and carbon tetrachloride. Of these, alkanethiols are preferred because of their high chain transfer rate and good physical property balance 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 to 10% by mass with respect to the total amount of unsaturated monomers used for polymerization of the (b) hydrophilic copolymer. Below this range, the processability at the time of mixing the photosensitive resin composition may be deteriorated, and above this range, the molecular weight may be significantly reduced.

A polymerization reaction inhibitor can be used for the polymerization of the (b) hydrophilic copolymer, if necessary.
The polymerization reaction inhibitor is a compound that reduces the radical polymerization rate by adding to the emulsion polymerization system. More specifically, the polymerization reaction inhibitor is 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, which is presumed to be effective in adjusting the physical properties of the latex film.

Examples of the polymerization reaction inhibitor include quinones such as o-, m- or p-benzoquinone; nitro compounds such as nitrobenzene, o-, m- or p-dinitrobenzene; amines such as diphenylamine; Catechol derivatives such as tributyl catechol; 1,1-disubstituted vinyl compounds such as 1,1-diphenylethylene or α-methylstyrene, 2,4-diphenyl-4-methyl-1-pentene; 2,4-diphenyl 1,2-disubstituted vinyl compounds such as -4-methyl-2-pentene and cyclohexene; and the like. 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 preferable from the viewpoint of reactivity. These polymerization reaction inhibitors may be used alone or in combination of two or more.
The amount of the polymerization reaction inhibitor used is preferably 10% by mass or less based on the total amount of unsaturated monomers used for the polymerization of the (b) hydrophilic copolymer. If it exceeds 10% by mass, the polymerization rate tends to be significantly reduced.

The above-mentioned radical polymerization initiator radically decomposes in the presence of heat or a reducing substance to start addition polymerization of the monomer, and either an inorganic initiator or an organic initiator can be used.
Examples of the above radical polymerization initiator include water-soluble or oil-soluble peroxodisulfates, peroxides, azobis compounds, etc. Specifically, potassium peroxodisulfate, sodium peroxodisulfate, ammonium peroxodisulfate, Hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide, 2,2-azobisbutyronitrile, cumene hydroperoxide and the like can be mentioned. As said radical polymerization initiator, POLYMER HANDBOOK (3rd edition), J.F. Brandrup and E.I. H. The compounds described in Immergut, John Willy & Sons (1989) can also be used. 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 suitable as a polymerization initiator.
The amount of the polymerization initiator used is usually from 0.1 to 5.0% by mass, preferably 0.2 based on the total amount of unsaturated monomers used for the polymerization of the (b) hydrophilic copolymer. It is selected from the range of -3.0% by mass. If the amount of the polymerization initiator used is less than 0.1% by mass, stability during synthesis of the (b) hydrophilic copolymer may not be obtained, and the amount of the polymerization initiator used exceeds 5.0% by mass In such a case, the moisture absorption of the photosensitive resin composition may increase.

  (B) At the time of synthesis of the hydrophilic copolymer, various polymerization modifiers can be added as needed. As a pH adjuster, for example, a pH adjuster such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium hydrogencarbonate, sodium carbonate, disodium hydrogenphosphate or the like can be added as a polymerization modifier. Also, various chelating agents such as sodium ethylenediaminetetraacetate can be added as a polymerization regulator. Further, as other additives, alkali-sensitive latex, viscosity reducing agent such as hexametaphosphoric acid, polyvinyl alcohol, water-soluble polymer such as carboxymethyl cellulose, thickener, various anti-aging agents, ultraviolet light absorbers, preservatives, bactericides Add various additives such as antifoaming agent, dispersant such as sodium polyacrylate, water resistance agent, metal oxide such as zinc flower, isocyanate compound, crosslinking agent such as epoxy compound, lubricant, water retention agent etc. It is also good. The addition method of these additives is not particularly limited, and it can be added at the time of synthesis of the (b) hydrophilic copolymer, regardless of after synthesis.

  The polymerization temperature in the case of emulsion-polymerizing the (b) hydrophilic copolymer is usually selected in the range of 60 to 120 ° C. Further, polymerization may be performed at a lower temperature by the above-mentioned redox polymerization method or the like. Furthermore, as the oxidation reduction 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 (b) is preferably in the form of particles, and the average particle size thereof is preferably 500 nm or less, more preferably 100 nm or less. When the average particle size is too large, the aqueous developability of the obtained printing plate precursor may be reduced.

Moreover, it is preferable that the toluene gel fraction of (b) hydrophilic copolymer is 60 to 99%. When the gel fraction is less than 60%, the strength of the resulting printing plate tends to be reduced. When the gel fraction is more than 99%, the mixing properties of (b) the hydrophilic copolymer and (a) the thermoplastic elastomer tend to be significantly reduced.
Here, with the toluene gel fraction, an appropriate amount of (b) a dispersion of about 30% by weight of a hydrophilic copolymer is dropped on a Teflon sheet and dried at 130 ° C. for 30 minutes (b) hydrophilic 0.5 g of the copolymer was taken, which was immersed in 30 ml of toluene at 25 ° C., shaken for 3 hours using a shaker, filtered through 320 SUS mesh, and dried at 130 ° C. for 1 hour for non-passing components The mass fraction (%) obtained by dividing the subsequent mass by 0.5 (g).

  The content of the (b) hydrophilic copolymer in the photosensitive resin layer is 100 wt% of the total amount of the photosensitive resin composition from the viewpoint of developability during plate preparation when developing in an aqueous developer. It is preferable that the concentration be 10 wt% to 75 wt%. The content of the (b) hydrophilic copolymer is more preferably 15 wt% to 65 wt%, and still more preferably 20 wt% to 60 wt%.

((C) photopolymerizable monomer)
Examples of the photopolymerizable monomer (c) include esters of acids such as acrylic acid, methacrylic acid, fumaric acid and maleic acid, derivatives of acrylamide and methacrylamide, allyl esters, styrene and derivatives thereof, N-substituted maleimide compounds, etc. Can be mentioned.

  Specific examples of the photopolymerizable monomer (c) include diacrylates and dimethacrylates of alkanediols such as 1,6-hexanediol and 1,9-nonanediol, or ethylene glycol, diethylene glycol, propylene glycol and dipropylene. Glycol, polyethylene glycol, butylene glycol, diacrylates and dimethacrylates of dicyclopentadienyl, trimethylolpropane tri (meth) acrylate, dimethylol tricyclodecane di (meth) acrylate, isoboronyl (meth) acrylate, phenoxy polyethylene glycol ( Meta) acrylate, pentaerythritol tetra (meth) acrylate, N, N'-hexamethylene bisacrylamide and methacrylamide, styrene, vinylto En, divinylbenzene, diacrylic phthalate, triallyl cyanurate, fumaric acid diethyl ester, fumaric acid dibutyl ester, fumaric acid dioctyl ester, fumaric acid distearyl ester, fumaric acid butyl octyl ester, fumaric acid diphenyl ester, fumaric acid dibenzyl Esters, 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 and the like can be mentioned. These may be used alone or in combination of two or more.

  It is preferable to contain 2.0 wt% or more of a monomer having 2 mol of a methacrylate group in the resin composition, from the viewpoint of higher resistance to scuffing of the convex portion of the printing plate.

The content of the (c) photopolymerizable monomer in the photosensitive resin layer is the total of the thermoplastic elastomer and / or the hydrophilic polymer and the liquid rubber component such as conjugated diene rubber described later from the viewpoint of the flexibility of the flexographic printing plate It is desirable that the ratio with is 15% or less.
In addition, when the total amount of the photosensitive resin composition is 100 wt% in order to obtain bright printing, the content of the (c) photopolymerizable monomer is more preferably 5 wt% to 20 wt%, and 8 wt% to More preferably, it is 15 wt%.

(Photopolymerization initiator)
The photopolymerization initiator is a compound which absorbs light energy and generates a radical, and various known ones can be used, and various organic carbonyl compounds and particularly aromatic carbonyl compounds are preferable.

  As specific examples, thioxanthones such as benzophenone, 4,4-bis (diethylamino) benzophenone, t-butyl anthraquinone, 2-ethyl anthraquinone, 2,4-diethyl thioxanthone, isopropyl thioxanthone, 2,4- dichloro thioxanthone; diethoxy Acetophenone, 2,2-dimethoxyphenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino (4-thio) Acetophenones such as methylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone; benzoin methyl ether, benzoin ethyl ether, ben Benzoin ethers such as in isopropyl ether and benzoin isobutyl ether; 2,4,6-trimethyl benzoyl diphenyl phosphine oxide, bis (2,6-dimethoxy benzoyl) -2,4,4-trimethyl pentyl phosphine oxide, bis (2,2, Acyl phosphine oxides such as 4,6-trimethyl benzoyl) -phenyl phosphine oxide; methyl benzoyl formate; 1,7-bisacridinyl heptane; 9-phenyl acridine; 2,6-di-t-butyl-p- Cresol; etc. These may be used alone or in combination of two or more.

  The content of the photopolymerization initiator in the photosensitive resin layer is 0.1 wt% to 100 wt% when the total amount of the photosensitive resin composition is 100 wt% in order to enhance plate formability during plate making and obtain bright printing. It is preferable that it is 10.0 wt%. The content of the photopolymerization initiator is more preferably 1.0 wt% to 8.0 wt%, and further preferably 1.5 wt% to 5.0 wt%.

  In addition, as the photopolymerization initiator, a disintegrating photopolymerization initiator and a hydrogen abstraction type photopolymerization initiator may be used in combination. The amount of the hydrogen abstraction type photopolymerization initiator in the photosensitive resin composition is preferably 1.0 wt% or less because the image reproducibility of the printing plate and the abrasion resistance are high. 0.5 wt% or less is more preferable.

((D) Other ingredients)
The flexographic printing plate precursor of the present embodiment includes, in addition to the components (a) to (c), as the other component (d), various auxiliary additives such as plasticizers, thermal polymerization inhibitors, ultraviolet light absorbers, halation It may contain an inhibitor, a light stabilizer, a photoluminescent tag (a substance that is excited by an external energy source and emits the obtained energy in the form of light and / or radiation), a silicone compound, and the like.

  As a plasticizer, hydrocarbon oils such as naphthenic oil and paraffin oil; conjugated diene rubbers mainly composed of liquid dienes such as liquid acrylonitrile-butadiene copolymer, liquid styrene-butadiene copolymer, etc .; number average molecular weight 2,000 The following polystyrene, sebacate ester, phthalate ester; hydrophilic copolymer etc. may be mentioned. A photopolymerizable reactive group may be added to these.

Among them, preferred is a conjugated diene rubber having a viscosity of 2000 Pa · s or less at 30 ° C., that is, a liquid diene as a main component, from the viewpoint of high flexibility and high image reproducibility of the printing plate. This viscosity can be measured in accordance with JIS-K-7117.
As the diene, isoprene and / or butadiene are preferable, and butadiene is more preferable because they are easily available. The conjugated diene rubber may be used in combination of two or more.

The vinyl group content in the total amount of dienes contained in the conjugated diene rubber is preferably 40 mol% or more, more preferably 60 mol% or more, and still more preferably 80 mol% or more, because the plate reproducibility can be increased during plate making. The vinyl content in the conjugated diene rubber can be determined from the aforementioned ¹ H-NMR (nuclear magnetic resonance spectrum).

The number average molecular weight (Mn) of the conjugated diene rubber is not particularly limited, but is preferably 1,000 to 50,000, more preferably 1,000 to 30,000, and 1,000 to 20,000. It is further preferred that
In addition, the number average molecular weight (Mn) in this invention is a polystyrene conversion molecular weight measured by gel permeation chromatography (GPC).

  As the conjugated diene rubber, for example, a butadiene homopolymer commercially available from Nippon Soda Co., Ltd., Kuraray Co., Ltd. and the like can be suitably used.

  When the photosensitive resin layer contains a plasticizer as the other component (d), the content of the plasticizer can shorten the development time, so 5 wt% to 50 wt% when the total amount of the photosensitive resin composition is 100 wt%. % Is preferred. The content of the plasticizer is more preferably 10 wt% to 40 wt%, further preferably 15 wt% to 35 wt%.

  The flexographic printing plate of the present embodiment may contain a silicone compound in the photosensitive resin layer from the viewpoint of controlling surface energy. The silicone compound is preferably contained in the photosensitive resin layer in an amount of 0.1 to 5.0%, more preferably 0.5 to 3.0%, still more preferably 0.5 to 2.0. It is more preferable to contain% or less.

  Examples of silicone compounds include silicone oils containing a siloxane unit (hereinafter simply referred to as silicone oils), silane coupling agents, silane compounds, silicone rubbers, silicone resins and the like. Among them, silicone oil is preferable because the component is easily transferred to the surface and the effect of reducing surface energy is high.

  Especially as a silicone compound, although molecular structure is not limited, a compound which has polyalkyl siloxanes, such as poly dimethyl siloxane and poly diethyl siloxane, in a principal chain can be mentioned as a desirable compound. Further, it may be a compound having a polysiloxane structure in a part of the molecule. Furthermore, a compound in which a specific organic group is introduced into the polysiloxane structure can be used. Specifically, a compound having an organic group introduced to the side chain of polysiloxane, a compound having an organic group introduced to both ends of polysiloxane, a compound having an organic group introduced to one end of polysiloxane, and a side chain of polysiloxane The compound etc. which introduce | transduced the organic group into both ends can be used.

Specific examples of the organic group introduced into the polysiloxane structure include an amino group, a carboxyl group, a carbinol group, an aryl group, an alkyl group, an alkoxycarbonyl group, an alkoxy group, and a linear or at least one aryl group. Examples thereof include branched alkyl groups and polyoxyalkylene groups (hereinafter also referred to as polyether groups).
Among the above organic groups, at least an amino group, a polyether group, and a carbinol group are preferable because the transparency of the photosensitive resin layer can be increased.
That is, the silicone compound is preferably a silicone modified with one or more selected from the group consisting of an amine, a polyether and a carbinol. The silicone compound is more preferably a silicone oil having a polysiloxane as a main skeleton and at least one end having one or more groups selected from the group consisting of an amino group, a polyether group and a carbinol group.

Examples of the amino group include primary to tertiary monoamino groups and diamino groups.
The polyether group is, for example, a linear polymer chain having an ether bond in the main chain, and includes polyalkylene oxides such as polyethylene glycol and polypropylene glycol, and polyphenylene oxide.

  The amino group equivalent (g / mol) in the silicone oil is preferably 300 g / mol to 1000 g / mol, and more preferably 350 g / mol to 800 g / mol.

  The number average molecular weight of the silicone compound is preferably 15,000 or less, more preferably 10,000 or less, still more preferably 3,000 or less because the transparency of the photosensitive resin composition is high and the image reproducibility of the printing plate is high. preferable.

  As the silicone compound, for example, various organic group-substituted silicone oils manufactured by Shin-Etsu Chemical Co., Ltd., manufactured by Asahi Kasei Wacker Silicone Co., Ltd., manufactured by GE Toshiba Silicone Co., Ltd., manufactured by Toray Dow Corning Silicone Co., Ltd. can be used.

[Method of producing flexographic printing plate precursor]
Hereinafter, the method of producing a flexographic printing original plate is demonstrated.

  The flexographic printing original plate has at least one photosensitive resin layer on a support film, and if necessary, a protective layer on the photosensitive resin layer, or an ultraviolet shielding layer that can be removed by an infrared laser, etc. May be included.

  Moreover, it is preferable to have an adhesive layer on a support film. The adhesive layer includes, for example, a composition having a binder polymer such as polyurethane, polyamide, thermoplastic elastomer and the like, and an adhesive active component such as an isocyanate compound and an ethylenic unsaturated compound. Furthermore, various auxiliary additive components such as plasticizers, thermal polymerization inhibitors, ultraviolet light absorbers, antihalation agents, light stabilizers, photopolymerization initiators, photopolymerizable monomers, dyes and the like are added to the adhesive layer. can do. In order to obtain higher adhesion between the adhesive layer and the polyester film as a support, it is preferable to provide at least one or more undercoat layers.

  Since the photosensitive resin composition constituting the photosensitive resin layer usually has tackiness, in order to improve the contact with the negative film to be overlaid thereon during plate making, or to allow reuse of the negative film In order to do so, a solvent-soluble protective layer may be provided on the surface of the photosensitive resin layer. As the protective layer, for example, it is preferable that the protective layer be thin and flexible, containing a substance soluble in a solvent used as a washing solution. Examples of the protective layer include those containing crystalline 1,2-polybutadiene, soluble polyamide, partially saponified polyvinyl acetate, cellulose ester and the like, and among these, soluble polyamide is preferable. These substances may be dissolved in an appropriate solvent and the solution may be directly coated on the surface of the photosensitive resin layer, or once coated on a film of polyester, polypropylene or the like, a film coated with the above substance may be a photosensitive resin. The layer may be laminated and transferred.

The protective layer may be an ultraviolet shielding layer containing an infrared sensitive substance, and the protective layer itself may be used as a negative by direct ablation with an infrared laser (hereinafter also referred to as laser drawing). In any case, when the unexposed area is washed out after the exposure is completed, this protective layer is also removed simultaneously.
The UV shielding layer is preferably composed of a binder polymer, an infrared sensitive material and a shielding material for non-infrared radiation. Examples of the binder polymer include polyamides, polyesters, and copolymers of a monovinyl-substituted aromatic hydrocarbon and a conjugated diene.
Among them, a copolymer composed of a monovinyl-substituted aromatic hydrocarbon such as styrene, α-methylstyrene, vinyl toluene and a conjugated diene such as 1,3-butadiene and isoprene is preferable. When the shielding layer for non-infrared radiation is constituted using the above-mentioned binder polymer, the affinity with the photosensitive composition resin is high, and the adhesion is good.

When polyester is used as the binder polymer, the number average molecular weight is preferably 300 or more and 10,000 or less.
Furthermore, as polyesters, for example, those synthesized from alkanediol and adipic acid, those synthesized from alkanediol and phthalic acid, polycaprolactone, and a combination of two or more of these polyesters are preferably listed. be able to. Also, the polyester may contain various functional groups such as amino group, nitro group, sulfonic acid group, halogen, etc. within the range not to impair the compatibility with other binder polymers, infrared sensitive substances and shielding substances of non-infrared radiation. It may be

As the infrared sensitive substance, for example, a single substance or a compound having a strong absorption usually in the range of 750 to 2000 nm is preferably used. Specific examples of the infrared sensitive substance include inorganic pigments such as carbon black, graphite, copper chromite, and chromium oxide; dyes such as polyphthalocyanine compounds, cyanine dyes, and metal thiolate dyes; and the like.
These infrared sensitive substances are added in such a range as to give a sensitivity that can be removed by the laser beam used. Generally, addition of 10 to 80 wt% is effective. As a non-infrared radiation shielding material, a material which reflects or absorbs radiation such as ultraviolet light can be used. Radiation absorbing agents such as ultraviolet rays, carbon black, graphite and the like are good examples, and the addition amount is set so that the required optical density can be achieved. In general, it is preferable to add such that the optical density is 2 or more, preferably 3 or more.

The method for producing the flexographic printing plate precursor is not particularly limited, and can be prepared by various methods. Specifically, the following methods may be mentioned.
First, the raw material of the photosensitive resin composition is dissolved in a suitable solvent, for example, a solvent such as chloroform, tetrachloroethylene, methyl ethyl ketone or toluene, mixed, and cast into a mold to evaporate the solvent. A method of forming into a plate shape, and a method of forming into a desired thickness by a calender roll, press or the like after kneading with a kneader, roll mill or screw extruder without using a solvent can be mentioned.

In order to provide a protective layer or an ultraviolet shielding layer on the surface of the photosensitive resin layer, for example, components constituting the protective layer or the ultraviolet shielding layer are dispersed or dissolved in an appropriate solvent by forced agitation or ultrasonic agitation with a stirring blade. After pre-kneading using an extruder or a kneader and then dispersing or dissolving in an appropriate solvent, the dispersion or solution may be coated directly on the photosensitive resin layer. Furthermore, a cover sheet made of polyester, polypropylene or the like may be provided on the protective layer or the ultraviolet shielding layer. Alternatively, the cover sheet may be coated with a solution of a protective layer or an ultraviolet shielding layer to form a protective film, and then the protective film may be laminated or pressed onto the photosensitive layer to transfer the protective film.
The protective film and the support are usually adhered to the photosensitive resin composition by roll lamination after sheet forming of the photosensitive resin composition, and heat pressing after lamination makes it possible to obtain a photosensitive resin layer with even better thickness accuracy.

[Method of producing flexographic printing plate]
In order to make a flexographic printing plate from a flexographic printing original plate, the following method is generally employed.
First, the entire surface is exposed to ultraviolet light (back exposure) through the support film of the flexographic printing original plate, and the photosensitive resin composition is cured to form a thin uniform cured layer.
Next, a negative film is placed on the photosensitive resin layer, and the ultraviolet blocking layer provided on the photosensitive resin layer is passed through the negative film, or laser drawing is performed, and then the photosensitive resin layer is directly coated from above the ultraviolet blocking layer. Image exposure (relief exposure) is performed on the surface.
Then, the unexposed area is either washed away with a solvent-based developer or an aqueous developer, or the unexposed area heated to 40 ° C. to 200 ° C. is brought into contact with the absorbing layer capable of absorbing the light, thereby removing the absorbing layer. Remove the part.
Furthermore, a flexographic printing plate is obtained by post-process exposure.

  Either of the exposure from the negative film side or the ultraviolet shielding layer side (relief exposure) and the exposure from the support film side (back exposure) may be performed first, or both may be performed simultaneously. Examples of the exposure light source include a high pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, and a xenon lamp.

  An infrared laser can be used for laser drawing, and it is preferable to use that whose wavelength is 750-2000 nm as this infrared laser. As an infrared laser of this wavelength, a semiconductor laser of 750-880 nm and an Nd-YAG laser of 1060 nm are generally used.

  When developing the unexposed area with a solvent, examples of developing solvents include esters such as heptyl acetate and 3-methoxybutyl acetate; petroleum fractions, hydrocarbons such as toluene and decalin; chlorinated organics such as tetrachlorethylene A mixture of a solvent and an alcohol such as propanol, butanol and pentanol; water; an ether such as polyoxyalkylene alkyl ether; and the like can be suitably mentioned.

  When the unexposed area is developed with a water-based developer, the water-based developer is a developer mainly composed of water, and may be water itself. For example, surface activity such as nonionicity or anionicity in water An agent, and, if necessary, a pH adjuster, a washing aid and the like may be blended.

  As a nonionic surfactant, for example, 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 adduct Etc.

  As the anionic surfactant, for example, linear alkylbenzene sulfonate having alkyl having an average of 8 to 16 carbon atoms, α-olefin sulfonate having an average of 10 to 20 carbon atoms, carbon number of an alkyl group or alkenyl group is 4 to 10 dialkyl sulfosuccinates, sulfonates of fatty acid lower alkyl esters, alkyl sulfates having an average of 10 to 20 carbon atoms, and linear or branched alkyl or alkenyl groups having an average of 10 to 20 carbon atoms And alkyl ether sulfates having an average of 0.5 to 8 moles of ethylene oxide added thereto, saturated or unsaturated fatty acid salts having an average of 10 to 22 carbon atoms, and the like.

  Moreover, as a pH adjuster, for example, sodium borate, sodium carbonate, sodium silicate, sodium metasilicate, sodium succinate, sodium acetate and the like can be mentioned. Among the above, sodium silicate is preferable because it is easily dissolved in water.

  Furthermore, a washing aid may be added to the developer. The cleaning aid is to increase the cleaning (development) ability of the developer by using the above-mentioned surfactant and pH adjuster in combination. Examples of the washing aid include amines such as monoethanolamine, diethanolamine and triethanolamine, ammonium salts such as tetramethylammonium hydroxide, paraffin hydrocarbons and the like.

One or more types selected from the group consisting of surfactants such as nonionic and anionic surfactants, pH adjusters, and washing assistants each have a developer content of 0.1 to 50% by mass, preferably 1 to 10 It can be used by adding and mixing in the range of mass%.
At the time of development, the printing base plate may be vibrated by ultrasonic waves or the like, the surface of the printing base plate may be scraped using mechanical means such as a brush, or the developer may be jetted from a nozzle.

  In addition, 0.01% to 5% of a silicone component is added from the viewpoint of obtaining a flexographic printing plate which can obtain bright printing and is excellent in ink entanglement and ink transferability in a solvent-based and / or aqueous developer. May be As the silicone component, those similar to the silicone compound in the above (e) in the photosensitive resin layer can be used. Among silicone compounds, the silicone component to be contained in the developer is preferably a silicone oil modified with an amino group, a polyether group, a carbinol group or the like.

  As an absorption layer of heat development, the absorption layer containing a nonwoven fabric material, a paper raw material, textile fiber, an open-cell foam, a porous material etc. is mentioned, for example. The absorbent layer is preferably a nonwoven material including nylon, polyester, polypropylene, polyethylene, and a combination of these nonwoven materials, and more preferably a nonwoven continuous web of nylon or polyester.

  Examples of post-treatment exposure include a method of irradiating the surface with light having a wavelength of 300 nm or less. If necessary, light larger than 300 nm may be used in combination.

  In addition, although the photosensitive resin layer of the flexographic printing original plate in this embodiment is useful for both solvent development and heat development, it can be suitably used especially for solvent development in terms of high image reproducibility of the printing plate. .

In addition, the method for producing a flexographic printing plate of the present embodiment can obtain bright printing, and from the viewpoint of obtaining a flexographic printing plate excellent in ink entanglement and ink transferability, flexographic printing after development before post-processing exposure The plate may be coated with a silicone component and / or a fluorine compound.
The silicone component to be applied may be reactive silicone or non-reactive silicone, and suitable examples include (meth) acrylic modified silicone.
As the fluorine-based compound to be applied, for example, a polyfluorinated ethylene compound, a poly (ethylene-fluorinated ethylene) compound, an acrylic copolymer having a perfluoroalkyl group in a side chain, a urethane-based heavy weight having a perfluoroalkyl group Preferable examples include combined polymers, ester polymers having a perfluoroalkyl group, and fluorine monomers.
The (meth) acrylic-modified reactive silicone oil and the fluorine compound may be used in combination of two or more.

The silicone component and / or the fluorine compound is preferably dissolved in a solvent and used as a solution.
As the solvent, it is preferable that the solvent adheres to the surface of the resin plate and permeates in the vicinity of the surface. By selecting the solvent that penetrates the surface of the resin plate and subjecting it to the post-exposure step, the (meth) acrylic-modified silicone component and / or the fluorine compound is firmly fixed to the resin surface (in the vicinity) be able to.
The concentration of the silicone component and / or the fluorine compound in the solution containing the silicone component and / or the fluorine compound is preferably 0.05 to 50 wt%.

As the solvent, specifically, solvents such as hydrocarbon, acetic acid ester, alcohol, ketone or glycol ether can be used. These may be used alone or in combination of two or more. In order to permeate the surface of the photosensitive resin plate, it is possible to use paraffin or glycol ether of the above-mentioned solvent in combination with water, or to add a nonionic surfactant having high permeability.
If necessary, an additive such as an antifoaming agent, an antioxidant or a preservative may be added to the solution containing the silicone component and / or the fluorine compound.

  Examples of the method for applying the photosensitive resin plate to the plate surface include solution application by spray, brush coating, immersion, a method of applying the solution with a cloth or sponge, and addition to a rinse solution after development and dropping it onto the plate surface. Among them, solution application by spray is preferable. The application may be carried out immediately after development if it is before post-exposure, or may be carried out after development and drying.

[Primer treatment]
The flexographic printing plate precursor and flexographic printing plate of the present embodiment are preferably subjected to primer treatment on the surface of the support film opposite to the surface on which the photosensitive resin layer is laminated. That is, it is preferable that the flexographic printing original plate and the flexographic printing plate of the present embodiment have a primer treatment layer on the surface opposite to the surface on which the photosensitive resin layer of the support film is laminated.
By the flexographic printing plate precursor and the flexographic printing plate of the present embodiment having a primer-treated layer, the adhesion between a substrate having adhesiveness such as a cushion tape and the flexographic printing plate can be improved and peeling can be further prevented. .
The primer treatment in this embodiment refers to, for example, forming a thin layer with a silane coupling agent, a titanium coupling agent, a silicone-based adhesion auxiliary agent, or the like.

The primer treatment in this embodiment can also be performed, for example, by applying a solution containing an ink pen, a spray paste, and a urethane resin, an acrylic resin, a vinyl resin, and a petroleum resin.
In the case of the application with the ink pen, a commercially available quick-drying magic pen may be used, and the pen may be used to draw a line.
Moreover, in the case of application by a spray paste, a commercially available spray can type sizing agent may be used, and it may be applied by spray injection.
Furthermore, when applying a solution containing a urethane resin, for example, a commercially available urethane resin may be dissolved in an organic solvent such as ethyl acetate and applied using a spray gun.
Among these applications, it is preferable to apply an ink pen and perform primer treatment because the application amount is easy to control and the application surface is easy to visually recognize and excellent in processing workability.

The thickness of the primer-treated layer is preferably 0.1 g / m ² or more and 30 g / m ² or less, more preferably 0.5 g / m ² or more and 15 g / m ² or less, from the viewpoint of reducing printing pressure. Preferably, it is 1 g / m ² or more and 5 g / m ² or less.

  A plastic material soluble in an organic solvent, for example, at least one material selected from the group consisting of urethane based, acrylic based, vinyl based, petroleum based resins, etc., is used to form the primer-treated layer. Is preferred.

The method of priming using an ink pen is specifically as follows.
The substrate film surface of the flexographic printing plate after plate making, that is, the surface which becomes the end in the circumferential direction of the printing cylinder, uses Magic Ink No. 500 (black color) / Teranishi Chemical Industry Co., Ltd. as a primer, and uses a pen tip. The primer treatment can be carried out by applying a weight of 1 g / m ² after drying with an application width of 15 mm and then naturally drying at 0 to 50 ° C. for 1 to 60 minutes so as to draw a line from.

  The location to be subjected to the primer treatment is preferably a circumferential end of the printing cylinder. Further, the width to be treated is preferably 0 mm over 100 mm from the end, more preferably 1 mm or more and 50 mm or less, and preferably 5 mm or more and 30 mm or less.

  The flexographic printing plate of the present embodiment is strongly bonded to the adhesive substrate, and prevents the flexographic printing plate from peeling off from the substrate. Examples of the adhesive base material include a base material to be attached to a sleeve used when mounted on a cylinder of a flexographic printing machine, and specifically, a cushion tape, a double-sided adhesive tape, etc. is there. In addition, recently, there can also be mentioned a technique of directly sticking a printing plate structure on a sleeve having an adhesive property on the surface.

  Hereinafter, the present invention will be more specifically described using examples and comparative examples. The present invention is not limited at all by the following examples.

(Plate thickness)
Plate thickness was measured by a thickness gauge.

(Support film thickness)
The support film thickness was measured by a thickness meter.

(Bending stress of flexographic printing plate (gf / inch))
Place the flexographic printing plate with the support film face down on two fulcrums provided 40 mm wide, and use the tensile tester (Sima Tatsumi Co., Ltd.) to push the center between the fulcrums with the load cell of the tensile tester. The maximum load of (the flexographic printing plate was bent and immediately before the measurement load dropped) was measured as bending stress. The weight of the load cell was 100 g, and the speed of movement of the load cell when pushing the load cell was 10 mm / min.

(Edge lift resistance evaluation)
For a flexographic printing plate (90 mm × 380 mm), wrap a 2.54 mm flexographic printing plate on a 120 mm φ plastic sleeve (Rolltech Co., Ltd.) using cushion tape (E1020, manufactured by Sumitomo 3M), and after 15 hours I confirmed the floating state of.
The case where peeling was not observed in the edge portion was ◎, the case where the peeling width of the edge portion was less than 5 mm was ○, and the case where the peeling width of the edge portion was 5 mm or more was Δ.

(Stiffness evaluation)
A schematic diagram of stiffness evaluation is shown in FIG.
For flexographic printing plate material 1 (30 mm × 150 mm), place flexographic printing plate material 1 with support film face down on two fulcrums 2 provided at 110 mm width, and fulcrum position center part after 1 minute The sinking amount 3 of the printing plate material from the above was measured. The case where the amount of sinking is less than 5 mm is ○, 5 mm or more and less than 10 mm is △, and the case of 10 mm or more is x.

Preparation Example 1 Synthesis of Hydrophilic Copolymer A 125 parts by mass of water and (α-sulfo (1-nonylphenoxy) methyl as a reactive emulsifier in a pressure resistant reactor equipped with a stirrer and a temperature control jacket Ammonium salt of -2- (2-propenyloxy) ethoxy-poly (oxy-1,2-ethanediyl) 2 parts by mass of “Adecaria soap” (manufactured by Asahi Denka Kogyo Co., Ltd.) is initially charged, and the internal temperature is raised to 80 ° C. A mixture of a monomer mixture consisting of 10 parts by mass of styrene, 60 parts by mass of butadiene, 23 parts by mass of butyl 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 Solution, 28 parts by mass of water, 1.2 parts by mass of sodium peroxodisulfate, 0.2 parts by mass of sodium hydroxide, and (α-sulfo (1-nonylphenoxy) Chill-2- (2-propenyloxy) ethoxy - it was added poly (oxy-1,2-ethanediyl) ammonium salt 2 parts by weight aqueous solution of the 5 hours and 6 hours, respectively at a constant flow rate.
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).
Water was removed by drying up the obtained aqueous dispersion of the hydrophilic copolymer with a vacuum dryer at 50 ° C. to obtain a hydrophilic copolymer A.

[Production Example 2] Production of Thermoplastic Elastomer A After thoroughly substituting the interior of a 10 L stainless steel reactor equipped with a jacket and a stirrer with nitrogen, 7000 cc of cyclohexane, 1 g of tetrahydrofuran, N, N, N ', N'-tetramethylethylenediamine 3.5 g and 170 g of styrene were charged. Hot water was passed through the jacket to set the contents at about 70 ° C. After this, an n-butyllithium cyclohexane solution (1.15 g pure) was added to initiate polymerization of styrene. After the styrene was completely polymerized, 830 g of butadiene (1,3-butadiene) was added to continue the polymerization. Four minutes after polymerization of butadiene was completely completed, 0.83 g of tetramethoxysilane was added to cause a coupling reaction. A portion of the obtained block copolymer solution was sampled, and then the solvent was removed by heating. The polymer had a styrene content of 17 wt% and a 1,2-vinyl content in the butadiene polymer block of 55 mol%. Moreover, the number average molecular weight was 240,000. The styrene content was measured using ultraviolet spectroscopy (UV). In addition, the vinyl content was measured by infrared analysis (IR) and calculated by the Hampton method. The number average molecular weight was a polystyrene equivalent molecular weight measured by gel permeation chromatography (GPC). As a measuring device, LC-10 (manufactured by Shimadzu Corporation, trade name), using two TSK gel GMH XL (4.6 mm ID × 30 cm) in a column, using tetrahydrofuran (1.0 ml / min) as a solvent, and the oven temperature The measurement was performed at 40 ° C.

  Next, using the block copolymer solution from which the solvent was removed, hydrogenation was performed at a temperature of 70 ° C. using biscyclopentadienyl titanium chloride and n-butyllithium as a hydrogenation catalyst. The hydrogenation rate was controlled by measuring the amount of hydrogen gas supplied with a flow meter and stopping the gas supply when the target hydrogenation rate was achieved. Thereafter, 10 g of water is added, and after stirring, 3.0 g of n-octadecyl-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate, 2,4-bis (n-) 1.5 g of octylthiomethyl) -O-cresol was added. The solvent was removed by steam stripping the obtained solution to obtain a water-containing crumb. Subsequently, this water-containing crumb is dehydrated and dried by a heat roll, and a block copolymer having 45 mol% of 1,4-butadiene units, 35 mol% of 1,2-vinyl content and 20 mol% of butylene units in a butadiene polymer block The thermoplastic elastomer A was obtained. The hydrogenation rate was confirmed using a nuclear magnetic resonance apparatus (NMR).

Production Example 3 Production of Base Film (Support) As a solution for an adhesive layer coated on a support film, Tufprene 912 (a product of Asahi Kasei Corporation, a product made by Asahi Kasei Corporation) is a block copolymer of styrene and 1,3-butadiene. Of paraffin oil (average carbon number 33, average molecular weight 470, density 0.868 at 15 ° C.) 38 parts by weight, 2.5 parts by weight of 1,9-nonanediol diacrylate, 2,2 -1.5 parts by mass of dimethoxy-phenylacetophenone, 3 parts by mass of epoxy ester 3000 M (made by Kyoeisha Chemical Co., Ltd., trade name), and 1.5 parts by mass of Varifast Yellow 3150 (made by Orient Chemical Industries, trade name) Was dissolved in toluene to obtain a solution of 25% solids, and then a 188 μm polyester using a knife coater It was applied to one side of the film so as to have an ultraviolet light transmittance of 10%, and was dried at 80 ° C. for 1 minute to obtain a support having an adhesive layer. The UV transmittance of the support is measured using a UV exposure device AFP-1500 (trade name, manufactured by Asahi Kasei Co., Ltd.) and a UV luminometer MO-2 type machine (trade name, UV-35 filter, manufactured by Oak Manufacturing Co., Ltd.). Was measured and calculated.
The support film used was a 188 μm polyester film (Toray, PET Lumirror), a 125 μm polyester film (Toyobo, E5100), and a 225 μm polyester film (Toray, PET U35).

Production Example 4 Preparation of Cover Film (Infrared-Sensitive Layer) First, 65 wt% of Asaflex 810 (trade name, manufactured by Asahi Kasei Corporation), which is a block copolymer of styrene and 1,3-butadiene, was used as an infrared-sensitive material. After kneading 35 wt% of carbon black with a kneader and cutting into pellets, ethyl acetate / butyl acetate / propylene glycol monomethyl ether acetate = 50 in a ratio of 90 parts by mass of this pellet and 10 parts by mass of 1,6-hexanediol adipate. The mixture was dissolved in a mixed solvent prepared at a weight ratio of / 30/20 using ultrasonic waves to prepare a homogeneous solution with a solid content of 12 wt%. Next, this solution is coated on a polyester film as a cover sheet with a thickness of 100 μm using a knife coater so that the coated amount after drying is 4 to 5 g / m ^2, and dried at 80 ° C. for 1 minute Thus, a protective film having an infrared-ray-cutable ultraviolet shielding layer was obtained. It was 3-4 when the optical density of this protective film was measured by DM-500 (Dainippon Screen Mfg. Co., Ltd. make, brand name).

Example 1
(Preparation of flexographic printing plate precursor)
30 parts by mass of a styrene-butadiene-styrene copolymer [D-KX 405: manufactured by Clayton] as a thermoplastic elastomer (a), and the hydrophilic copolymer obtained in Production Example 1 as a hydrophilic copolymer (b) After mixing 30 parts by mass of A at 140 ° C. using a pressure kneader, (d) others, 27 parts by mass of liquid polybutadiene [LBR-352: manufactured by Kuraray], 1,9 as a photopolymerizable monomer (c) 8 parts by mass of nonanediol diacrylate, 5 parts by mass of 1,6-hexanediol dimethacrylate, 2 parts by mass of 2,2-dimethoxyphenylacetophenone as a photopolymerization initiator, 2,6-di-t-butyl-p- A liquid mixture of 1 part by mass of cresol was gradually added over 15 minutes, and after addition, the mixture was further kneaded for 20 minutes to obtain a photosensitive resin composition. In addition, (d) and others have the said liquid polybutadiene as a main component, and contained less than 1 mass part of dyes.
The photosensitive resin composition was taken out and sandwiched between the base film obtained in Production Example 3 and 100 μm-thick PET coated with a 5 μm-thick polyvinyl alcohol (PVA) layer, and heated to 120 ° C. It was molded into a plate having a thickness of 1.14 mm using a press, and then the PET coated with the PVA layer was peeled off to obtain a laminate comprising a support (PET) -photosensitive layer.
An infrared ablation layer in which the cover film obtained in Production Example 4 was laminated was laminated on the obtained laminate so as to be in contact with the photosensitive layer, to obtain a printing original plate.

(Production of printing plate)
UV exposure machine (JE-A2-SS manufactured by Nippon Denshi Seiki 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 Exposure was carried out using.
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 8000 mJ was exposed from the side of the infrared ablation layer under the atmospheric atmosphere using the exposure machine. .
After exposure, an aqueous solution (water-based developer) of 1% polyoxyalkylene alkyl ether (Nyukol 2308: manufactured by Nippon Emulsifier) and 1% potassium carbonate is prepared, and washed using a JNW-A3-P manufactured by JEOL. The resultant was washed (developed) at 40 ° C. to remove the unexposed area.
After drying at 50 ° C. for 10 minutes, the printing plate was obtained by post-exposure with a UV sterilization lamp and a UV chemical lamp in order to obtain surface tackiness.

(Primer treatment)
Using Magic Ink No. 500 (black color, Teranishi Chemical Industry Co., Ltd.) as a primer on the support film surface of the flexographic printing plate after plate making (that is, the surface that becomes the circumferential end of the printing cylinder) It applied so that the mass after drying may be 1 g / m < ² > by application width 15 mm so that a line might be drawn from a pen point. Then, it was naturally dried at room temperature 20 degrees for 10 minutes. The primer was applied to both ends in the circumferential direction.

Example 2
A flexographic printing original plate and a flexographic printing plate were obtained in the same manner as in Example 1 except that the primer treatment was not performed.

[Example 3]
60 parts by mass of thermoplastic elastomer A as thermoplastic elastomer (a), without using hydrophilic copolymer (b), and as (d) others, 1,2-polybutadiene homopolymer B-2000 (Nippon Soda Co., Ltd.) And 30 parts by mass, and using 10 parts by mass of 1,9-nonanediol diacrylate as the photopolymerizable monomer (c) in the same manner as in Example 2, except that And, obtained flexographic printing plate. In addition, (d) and others have the above-mentioned 1,2-polybutadiene homopolymer as a main component, and contained less than 1 part by mass of a dye.

Example 4
A flexographic printing original plate and a flexographic printing plate were obtained in the same manner as in Example 3, except that the press was used to form a plate having a thickness of 1.70 mm.

[Example 5]
Using 67.5 parts by mass of thermoplastic elastomer A as the thermoplastic elastomer (a), without using the hydrophilic copolymer (b), and as (d) others, 1,2-polybutadiene homopolymer B-2000 A flexographic printing original plate was used in the same manner as in Example 3, except that 26 parts by mass was used, and the amount of 1,9-nonanediol diacrylate used as the photopolymerizable monomer (c) was 6.5 parts by mass. And, the flexographic printing plate was obtained. In addition, (d) and others have the above-mentioned 1,2-polybutadiene homopolymer as a main component, and contained less than 1 part by mass of a dye.

Comparative Example 1
The amount of D-KX 405 used is 60 parts by mass as the thermoplastic elastomer (a) without using hydrophilic copolymer A, and the amount of LBR 352 used is 10 parts by mass and 1,2- (d) as others. A flexographic printing plate precursor and a flexographic printing plate were obtained in the same manner as in Example 2 except that 15 parts by mass of polybutadiene homopolymer B-2000 was used.

Comparative Example 2
The amount of thermoplastic elastomer A used is 13 parts by mass, the amount of LBR 352 used as (d) and others is 21 parts by mass, and the amount of 1,9-nonanediol diacrylate used as photopolymerizable monomer (c) is 8 A flexographic printing plate and a flexographic printing plate were obtained in the same manner as in Example 3, except that the amount is 1, and the amount of 1,6-hexanediol dimethacrylate used is 8 parts by mass. In addition, (d) and others have the said liquid polybutadiene as a main component, and contained less than 1 mass part of dyes.

Comparative Example 3
A flexographic printing original plate and a flexographic printing plate were obtained in the same manner as in Example 1 except that the support film thickness was 250 μm and no primer treatment was performed.

  Composition of flexographic printing plate composition of Examples 1 to 5 and Comparative Examples 1 to 4, composition of cleaning solution used for development during plate making, method of coating silicone and / or fluorine compound, plate physical properties, printing characteristics Is shown in Table 1.

The terms in Table 1 are as follows.
Magic ink 500: Ink pen (made by Teranishi Chemical Industry Co., Ltd.)

  The flexographic printing plate of the present invention has industrial applicability in the field of flexographic printing.

1: Flexographic printing plate material 2: Support point 3: Subduction amount

Claims (8)

A flexographic printing plate in which a photosensitive resin layer is laminated on at least a support film,
The flexural modulus of the flexographic printing plate material before photopolymerization is 20 gf / inch or more, and
A flexographic printing plate, wherein the flexural modulus of the flexographic printing plate after photopolymerization is 100 gf / inch or less. The photosensitive resin layer comprises a photosensitive resin composition containing a thermoplastic elastomer (a) and a photopolymerizable monomer (c),
The multiplicative value of the mass percent concentration of the thermoplastic elastomer (a) in the photosensitive resin composition and the mass percent concentration of the photopolymerizable monomer (c) is not less than 0.030 and less than 0.070. Flexographic printing plate as described.   The flexographic printing plate as claimed in claim 1, wherein the thickness is 2.0 mm or less.   The flexographic printing plate as described in any one of Claims 1-3 whose thickness of a support film is 100 micrometers or more and 200 micrometers or less.   The flexographic printing plate according to any one of claims 1 to 4, wherein the support film is polyethylene terephthalate.   The flexographic printing plate as described in any one of Claims 1-5 which has a primer process layer in the surface on the opposite side to the surface on which the said photosensitive resin layer of the said support film was laminated | stacked. The flexographic printing plate according to claim 6, wherein the thickness of the primer-treated layer is 0.1 g / m ^{2 to} 30 g / m ² .   The flexographic printing plate according to claim 6, wherein a plastic material soluble in an organic solvent is used to form the primer treatment layer.