JP2015150805A - Resin composition for laser engraving, original film for laser engraving type flexographic printing plate and method for manufacturing the same, and flexographic printing plate and method for platemaking the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an original film for a laser engraving type flexographic printing plate which can obtain a flexographic printing plate having excellent printing resistance and has excellent engraving sensitivity, thermal stability at the time of manufacture and engraving residue rinsing properties and a method for manufacturing the same; and a method for platemaking a flexographic printing plate; and a resin composition for laser engraving which is suitably used for the original film for the printing plate.SOLUTION: A resin composition for laser engraving contains (component A) polymer particles containing a metathesis catalyst, and (component B) a polymer having an ethylenically unsaturated group.

Description

  The present invention relates to a resin composition for laser engraving, a laser engraving flexographic printing plate precursor and a method for producing the same, a flexographic printing plate and a method for making the same.

Many so-called “direct engraving CTP methods” have been proposed in which a relief forming layer is directly engraved with a laser to make a plate. In this method, the flexographic original plate is directly irradiated with a laser, and thermal decomposition and volatilization are caused in the relief forming layer by photothermal conversion to form a recess. Unlike the relief formation using the original film, the direct engraving CTP method can freely control the relief shape. For this reason, when an image such as a letter is formed, the area is engraved deeper than other areas, or the fine halftone dot image is engraved with a shoulder in consideration of resistance to printing pressure. Is also possible. In general, a high-power carbon dioxide laser is used as a laser for this method. In the case of a carbon dioxide laser, all organic compounds can absorb irradiation energy and convert it into heat. On the other hand, inexpensive and small semiconductor lasers have been developed. However, since these are visible and near infrared light, it is necessary to absorb the laser light and convert it into heat.
As a conventional flexographic printing plate, for example, the one described in Patent Document 1 is known.

JP 2007-272080 A

The problem to be solved by the present invention is that a flexographic printing plate having excellent printing durability can be obtained. It is to provide a manufacturing method thereof, a flexographic printing plate and a plate making method thereof.
Another problem to be solved by the present invention is to provide a resin composition for laser engraving that is suitably used for such a printing plate precursor.

The above-described problems of the present invention have been solved by the means described in <1>, <8> to <10>, <14> or <16> below. It is described below together with <2> to <7>, <11> to <13> and <15> which are preferred embodiments.
<1> A resin composition for laser engraving, comprising (Component A) polymer particles containing a metathesis catalyst, and (Component B) a polymer having an ethylenically unsaturated group,
<2> The resin composition for laser engraving according to <1>, wherein the component B has a weight average molecular weight of 500,000 or more,
<3> (Component C) The resin composition for laser engraving according to <1> or <2>, further containing a crosslinking agent,
<4> The resin composition for laser engraving according to <3>, wherein Component C is a peroxide,
<5> The resin composition for laser engraving according to any one of the above <1> to <4>, wherein Component B is a plastomer at 20 ° C.
<6> (Component D) The resin composition for laser engraving according to any one of <1> to <5>, further containing a photothermal conversion agent,
<7> The resin composition for laser engraving according to <6>, wherein Component D is carbon black,
<8> Laser engraving-type flexographic printing plate precursor having a relief forming layer comprising the resin composition for laser engraving according to any one of <1> to <7> above,
<9> A laser engraving-type flexographic printing plate precursor having a crosslinked relief-forming layer obtained by crosslinking a relief-forming layer made of the resin composition for laser engraving according to any one of the above <1> to <7>,
<10> A layer forming step of forming a relief forming layer comprising the resin composition for laser engraving according to any one of the above <1> to <7>, and the relief forming layer by light and / or heat A method for producing a laser engraving type flexographic printing plate precursor, comprising a crosslinking step of obtaining a flexographic printing plate precursor having a crosslinked relief forming layer by crosslinking
<11> The laser engraving flexographic printing according to <10>, wherein the layer forming step includes a step of kneading the resin composition for laser engraving and a step of molding the obtained kneaded material into a sheet shape. A method for producing an original plate,
<12> The method for producing a laser engraving-type flexographic printing plate precursor according to <1>, wherein the step of forming the sheet into a sheet is a step of forming into a sheet by hot pressing or extrusion,
<13> The method for producing a laser engraving-type flexographic printing plate precursor according to any one of <10> to <12>, wherein the relief forming layer is crosslinked by heat in the crosslinking step,
<14> Prepare the laser engraving type flexographic printing plate precursor described in <9> above or the laser engraving type flexographic printing plate precursor produced by the manufacturing method described in any one of <10> to <13> above. A method for making a flexographic printing plate, comprising: a step, and a engraving step for laser engraving the flexographic printing plate precursor for laser engraving to form a relief layer;
<15> The method for making a flexographic printing plate according to <14>, further comprising a rinsing step of rinsing the relief layer surface with an aqueous rinsing liquid after the engraving step,
<16> A flexographic printing plate obtained by the plate making method of a flexographic printing plate as described in <14> or <15> above.

According to the present invention, a flexographic printing plate excellent in printing durability can be obtained, and a laser engraving type flexographic printing plate precursor excellent in engraving sensitivity, thermal stability during production, and engraving residue rinsing, and a method for producing the same, In addition, a flexographic printing plate and a plate making method thereof could be provided.
Moreover, according to this invention, the resin composition for laser engravings used suitably for such a printing plate precursor could be provided.

Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In the present invention, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
In the present invention, “(Component A) polymer particles containing a metathesis catalyst” or the like is also simply referred to as “Component A” or the like.
Furthermore, in the description of the group (atomic group) in this specification, the description which does not describe substitution and unsubstituted includes the thing which has a substituent with the thing which does not have a substituent. For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
In the present invention, “parts by mass” and “% by mass” are synonymous with “parts by weight” and “% by weight”, respectively.
Moreover, in this invention, the combination of a preferable aspect is a more preferable aspect.

(Resin composition for laser engraving)
The resin composition for laser engraving of the present invention (hereinafter, also simply referred to as “resin composition” or “composition”) comprises (Component A) polymer particles containing a metathesis catalyst, and (Component B) an ethylenic resin. It contains a polymer having a saturated group.
Moreover, since the resin composition for laser engraving of the present invention is excellent in stability to heat, it can be suitably used for thermoforming.
Moreover, it is preferable that the resin composition for laser engraving of the present invention further contains (Component C) a cross-linking agent and (Component D) a photothermal generator, which will be described later.
Furthermore, the total content of Component A to Component D in the total solid content of the resin composition for laser engraving of the present invention is preferably 80% by weight or more, more preferably 90% by weight or more, and 95% by weight. % Or more is more preferable, and 98% by weight or more is particularly preferable. In addition, total solid means the thing remove | excluding volatile components, such as a solvent, from the component which comprises a resin composition.
Further, the resin composition for laser engraving of the present invention preferably does not contain a solvent, and when forming a relief forming layer in a flexographic printing plate precursor, without using a solvent, a melt extrusion method or a rubber extrusion method, The relief forming layer is preferably formed by thermoforming such as hot pressing.

As a result of intensive studies by the present inventor, the resin composition for laser engraving contains component A and component B, whereby a flexographic printing plate excellent in printing durability can be obtained, and laser engraving sensitivity, printing plate precursor production It has been found that it is possible to provide a resin composition for laser engraving which is excellent in thermal stability at the time and rinsing property of engraving residue generated during laser engraving.
Although the detailed mechanism is unknown, by adding the metathesis catalyst to the polymer composition and adding it to the resin composition, the polymer particle has excellent printing durability, and even if the resin composition contains the metathesis catalyst, The present inventor presumes that it is excellent in stability, laser engraving sensitivity and engraving residue rinsing properties.
Further, the present inventor presumes that the metathesis catalyst in the polymer particles functions in a decomposition product such as engraving residue during laser engraving and / or after laser engraving.

In the present specification, regarding the description of the flexographic printing plate precursor, the component A and the component B are contained, and the surface is a flat layer as an image forming layer to be subjected to laser engraving and is an uncrosslinked crosslinkable layer Is called a relief forming layer, a layer obtained by crosslinking the relief forming layer is called a crosslinked relief forming layer, and a layer in which irregularities are formed on the surface by laser engraving is called a relief layer.
Hereinafter, the components contained in the resin composition for laser engraving of the present invention will be described.

(Component A) Polymer Particles Containing Metathesis Catalyst The resin composition for laser engraving of the present invention contains (Component A) polymer particles containing a metathesis catalyst.
The metathesis catalyst that can be used in the present invention is not particularly limited as long as it is a compound that can catalyze the following reactions (A and B each independently represents an organic functional group, a halogen atom, or a hydrogen atom). References: RH Grubbs, "Handbook of Metathesis Vo. 1-3" (2003 WILEY-VCH Verlag GmbH & Co. KgaA, published by Weinheim), and the like.

The mechanism of action of the metathesis catalyst in the present invention is not clear, but is estimated as follows.
When a polymer such as polybutadiene is decomposed by a metathesis catalyst (lower figure), first, the metathesis catalyst (; M in the lower figure represents the metathesis catalyst) is inserted into the polymer main chain, and the metathesis catalyst is added to the polymer main chain. (Figure (A) below). Then, this polymer reacts with another polymer molecule (lower figure (B)), causing degradation of the polymer main chain by a metathesis reaction (lower figure (C)). It is presumed that this mechanism causes degradation of the polymer main chain (in other words, degradation of the composition).

Examples of the metathesis catalyst that can be used in the present invention include known metathesis catalysts such as Fischer-type carbene complexes, Schrock-type carbene complexes, Tebbe reagents, Grubbs catalysts, Hoveyda-Grubbs catalysts, Piers-Grubbs catalysts, Buffs. Preferred examples include a Mizer-Neuken catalyst and a glera catalyst, and more preferred examples include a Grubbs catalyst (first generation, second generation and third generation) and a Grubbs-Hoveyda catalyst (first generation and second generation).
The metathesis catalyst that can be used in the present invention is preferably a transition metal catalyst, more preferably a group 4-8 transition metal catalyst, and further preferably a group 6-8 transition metal catalyst. A group 8 transition metal catalyst is preferable, and a ruthenium catalyst is most preferable.
The metathesis catalyst is preferably a carbene complex.
Further, as a metathesis catalyst that can be used in the present invention, a reference document described in “Handbook of Metathesis Vo. 1-3” by RH Grubbs (2003 WILEY-VCH Verlag GmbH & Co. KgaA, published by Weinheim). Is given as a representative example.
The metathesis catalyst may be supported or bonded to a polymer carrier or an inorganic carrier.

  From the viewpoint of high catalytic performance of the metathesis catalyst, the metathesis catalyst is preferably a catalyst represented by the following formula (1).

In the formula, M represents Os or Ru, and R ¹ and R ² each independently represent a hydrogen atom, an unsubstituted or one or more aryl group, a halogen atom, a hydroxy group, an alkoxy group having 1 to 20 carbon atoms, or An alkyl group substituted with an alkoxycarbonyl group having 2 to 20 carbon atoms, unsubstituted or one or more alkyl groups having 1 to 20 carbon atoms, an aryl group, a halogen atom, a hydroxy group, an alkoxy group having 1 to 20 carbon atoms, or An alkenyl group substituted with an alkoxycarbonyl group having 2 to 20 carbon atoms, or an unsubstituted or one or more alkyl group having 1 to 20 carbon atoms, aryl group, hydroxy group, alkoxy group having 1 to 5 carbon atoms, amino Represents an aryl group substituted with a group, a nitro group or a halogen atom, X and X ¹ each independently represent an anionic ligand, L and L Each ¹ independently represents a neutral ligand, and R ² and L ¹ may be bonded to each other.

M is preferably Ru from the viewpoint of catalytic ability and stability in air.
From the viewpoint of catalytic ability and stability in air, R ¹ and R ² are each independently a hydrogen atom, an unsubstituted or one or more alkyl group having 1 to 20 carbon atoms, an aryl group, a halogen atom, a hydroxy group. An alkenyl group substituted with an alkoxy group having 1 to 20 carbon atoms or an alkoxycarbonyl group having 2 to 20 carbon atoms, or an unsubstituted or one or more alkyl group having 1 to 20 carbon atoms, an aryl group, a hydroxy group, An alkoxy group having 1 to 5 carbon atoms, an amino group, a nitro group, or an aryl group substituted with a halogen atom is preferable, and a hydrogen atom, a phenyl group, a 2,2-diphenylethenyl group, 2-methyl-1- More preferably, it is a propenyl group or a 2-isopropoxyphenyl group.
At least one of R ¹ and R ² is preferably a hydrogen atom.
Further, at least one of R ¹ and R ² is preferably a phenyl group, a 2,2-diphenylethenyl group, or a 2-methyl-1-propenyl group.
X and X ¹ may each independently be an anionic ligand that is covalently bonded to M or an anionic ligand that is ion-bonded.
X and X ¹ are each independently a halide ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, tetraarylborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, hydrogen sulfate It is preferably an ion, nitrate ion, nitrite ion, phosphate ion, hydrogen phosphate ion, dihydrogen phosphate ion, or carboxylate ion, more preferably a halide ion, and a chloride ion. It is particularly preferred.
X and X ¹ are preferably the same group from the viewpoint of synthesis.
L and L ¹ may be combined to be a bidentate neutral ligand.
L and L ¹ are each independently a phosphine compound, an imidazoline-2-ylidene compound, an alkyne compound, an arsine compound, a β-diketone compound, a ketoester compound, an ether compound, an amine compound, a pyridine compound, or an isonitrile compound. Preferably, it is a phosphine compound or an imidazoline-2-ylidene compound.
When R ² and L ¹ are bonded, R ² is preferably a 2-alkoxyphenyl group which may have a substituent, such as 2-isopropoxyphenyl group, 2-isopropoxy- 5-dimethylaminosulfonylphenyl group, 2-isopropoxy-5-acetoxyphenyl group, or 2-isopropoxy-5-trifluoroacetoxyphenyl group is more preferable, and 2-isopropoxyphenyl group is preferable. Particularly preferred.
Further, from the viewpoint of catalytic ability and stability in air, at least one of L and L ¹ is preferably a phosphine compound or an imidazoline-2-ylidene compound, and tricyclohexylphosphine, 1,3- Dimesitylimidazoline-2-ylidene or 1,3-di-o-toluylimidazoline-2-ylidene is more preferable, and tricyclohexylphosphine or 1,3-dimesitylimidazoline-2-ylidene More preferably.

  Although the preferable specific example of the metathesis catalyst used by this invention is given to the following, it is not necessarily limited to this. In the following formulae, Me represents a methyl group, t-Bu represents a t-butyl group, Cy represents a cyclohexyl group, Ar represents an aryl group, Ph represents a phenyl group, Pr represents an isopropyl group, Cps represents a cyclopentyl group, and Mes represents a mesityl group (1,3,5-trimethylphenyl group).

There is no restriction | limiting in particular as a polymer which can be used for the polymer particle of a component A, Although a well-known polymer can be used, a polyurethane resin, an acrylic resin, a polyurea resin, a polyester resin, a polycarbonate resin, a polyamide resin, or these Preferably, it is a polyurethane resin.
The polymer that can be used for the polymer particles of component A preferably has no ethylenically unsaturated groups.
The polymer that can be used for the polymer particles of component A is preferably a crosslinked polymer. That is, Component A is preferably crosslinked polymer particles containing a metathesis catalyst (hereinafter also referred to as “microgel”). By using a crosslinked polymer, the engraving residue rinsing property and the printing plate durability are excellent.
Among them, the component A is particularly preferably a crosslinked polyurethane resin particle.
The polymer particles in component A may be core-shell type polymer particles. The shell layer may be a single layer or two or more layers.

There is no restriction | limiting in particular as a manufacturing method of the component A, A well-known method can be used. For example, after mixing a metathesis catalyst with a polymer, a method of forming particles, a method of further forming a shell on the obtained particles, a metathesis catalyst mixed with a polymerizable compound used for polymer synthesis, polymerization is performed, Further, a metathesis catalyst is mixed in an oil phase containing a polymerizable compound, oligomer, polymer, etc. used for the synthesis of a polymer dispersed in an aqueous phase, and emulsion polymerization is performed as necessary. And a method of producing particles by removing the solvent.
Moreover, as a method of manufacturing the crosslinked polymer particle containing a metathesis catalyst, the manufacturing method of the following microgel (1) and the manufacturing method of microgel (2) can be mentioned suitably.

-Manufacturing method of microgel (1)-
In the microgel (1), a polyfunctional isocyanate compound having two or more isocyanate groups is dissolved in a water-immiscible solvent, and this solution is dissolved in one or more active hydrogen groups capable of reacting with isocyanate groups at one end. It is manufactured by emulsifying and dispersing in an aqueous solution containing the hydrophilic polymer having, and then removing the solvent from the oil droplets of the emulsified dispersion.

  As a method for producing the microgel (1), a known method can be applied as an operation. That is, an isocyanate compound that is soluble in a solvent immiscible with water, an oil phase solution in which a polyfunctional isocyanate compound having two or more isocyanate groups is dissolved in a solvent immiscible with water, and active hydrogen capable of reacting with isocyanate groups After preparing an aqueous solution containing a hydrophilic polymer having one or more groups at one end, both are mixed, and vigorously stirred and mixed, for example, at 12,000 rpm for 10 to 15 minutes using an emulsifier / disperser such as a homogenizer. Oil droplets are emulsified and dispersed in the phase. Next, the obtained emulsified dispersion is heated and stirred to evaporate the solvent, whereby an objective aqueous dispersion of microgel particles is obtained.

  In addition to the hydrophilic polymer having at least one active hydrogen group capable of reacting with an isocyanate group at one end, a compound having two or more active hydrogen atoms in the molecule is preferably added to the aqueous phase. Examples of such compounds include water, polyhydric alcohol compounds such as ethylene glycol and glycerin, polyhydric amine compounds such as ethylenediamine and diethylenetriamine, and mixtures thereof. Furthermore, it is preferable to contain a surfactant in order to improve emulsion dispersion stability.

Next, a polyfunctional isocyanate compound having two or more isocyanate groups will be described.
Specific examples of such a compound include, for example, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, as a bifunctional compound having two isocyanate groups in the molecule. Isocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4′-diisocyanate, 3,3′-dimethoxybiphenyl diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, xylylene-1,4-diisocyanate , Xylylene-1,3-diisocyanate, 4-chloroxylylene-1,3-diisocyanate, 2-methylxylylene-1,3-diisocyanate, 4,4′-diphenylpropane diisocyanate, 4,4′-diphenylhexafluoro Propane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,3-diisocyanate, cyclohexylene-1, Examples include 4-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,4-bis (isocyanatemethyl) cyclohexane, 1,3-bis (isocyanatemethyl) cyclohexane, isophorone diisocyanate, and lysine diisocyanate.

  In the present invention, trifunctional or higher functional isocyanate compounds can also be used. As an example of such a compound, the above-mentioned bifunctional isocyanate compound is used as a main raw material, these trimers (burette or isocyanurate), a polyfunctional adduct of a polyol such as trimethylolpropane and a bifunctional isocyanate compound. , Benzene isocyanate formalin condensate, polymers of isocyanate compounds having a polymerizable group such as methacryloyloxyethyl isocyanate, lysine triisocyanate, and the like can also be used. In particular, xylene diisocyanate and its hydrogenated product, hexamethylene diisocyanate, tolylene diisocyanate and its hydrogenated product are used as the main raw materials, and in addition to these trimers (burette or isosinurate), it is polyfunctional as an adduct with trimethylolpropane. These are preferred. These compounds are described in “Polyurethane Resin Handbook” (edited by Keiji Iwata, published by Nikkan Kogyo Shimbun (1987)).

  Among these, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, trimethylolpropane and xylylene-1,4-diisocyanate or xylylene- Adducts with 1,3-diisocyanate are preferred, addition of xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, trimethylolpropane and xylylene-1,4-diisocyanate or xylylene-1,3-diisocyanate The product is particularly preferred.

Next, a hydrophilic polymer having at least one active hydrogen group capable of reacting with an isocyanate group at one end will be described.
Examples of the active hydrogen group that can react with the isocyanate group include a hydroxy group, an amino group, a mercapto group, and a carboxy group. Of these, a hydroxy group and an amino group are particularly preferable. Although it does not specifically limit as such a hydrophilic polymer which has an active hydrogen group, For example, the polyether etc. which have an active hydrogen group in one terminal are mentioned preferably.
The hydrophilic polymer has a weight average molecular weight (Mw) of preferably 300 to 500,000, and more preferably 500 to 100,000. When it is in the above range, it has a sufficient function as a protective colloid, can ensure the dispersion stability of the microcapsules, and can sufficiently obtain the hydrophilicity of the surface.

  Specific examples of the hydrophilic polymer include polyether oxides such as polyethylene oxide and ethylene oxide / propylene oxide copolymers. These polymers are, for example, ring-opening polymerization of a cyclic compound such as ethylene oxide and propylene oxide using alcohol, alkoxide, carboxylic acid, carboxylate, etc. as a polymerization initiation terminal, and the polymerization initiation terminal at a conventionally known reaction (for example, hydrolysis reaction). , Reduction reaction, etc.) can be synthesized by converting into an active hydrogen group such as hydroxy group or amino group. A polyether having an active hydrogen group at one end can also be used. Among these, polyethylene oxide monoethers (the monoethers include monomethyl ether, monoethyl ether, etc.), polyethylene oxide monoesters (the monoesters include monoacetate, mono (meth) acrylic acid) And esters are preferred.).

  The usage ratio of the polyfunctional isocyanate compound and the hydrophilic polymer is preferably 100/1 to 100/60, more preferably 100/2 to 100/30, more preferably 100/5 in terms of the molar ratio of isocyanate groups to active hydrogen groups. ~ 100/20 is most preferred. Within the above range, the dispersion stability is good, the wall crosslink density is not lowered, the inclusion leakage does not occur, and the stain resistance is also good.

-Manufacturing method of microgel (2)-
In the microgel (2), an oil phase in which an oligomer or polymer having three or more isocyanate groups and an oligomer or polymer having three or more hydroxy groups are dissolved and / or dispersed in a solvent together with a metathesis catalyst is dispersed in an aqueous phase. In this case, the solvent and the aqueous phase are sequentially removed.
The oligomer or polymer having three or more isocyanate groups is preferably an adduct of a trifunctional or higher functional polyol compound and a bifunctional isocyanate compound, and is an adduct of a trifunctional polyol compound and a bifunctional isocyanate compound. Is more preferable, and an adduct of a trifunctional phenol compound and a bifunctional isocyanate compound is still more preferable.
The oligomer or polymer having 3 or more hydroxy groups is preferably an adduct of a trifunctional or higher functional polyol compound, a bifunctional isocyanate compound and a monofunctional alcohol compound, and a trifunctional polyol compound, a bifunctional isocyanate compound and 1 More preferred are adducts with functional alcohol compounds, and even more preferred are adducts of trifunctional polyol compounds, bifunctional isocyanate compounds and polyalkylene glycol monoalkyl ethers.

Preferred examples of the bifunctional isocyanate compound used in the production of the microgel (2) include those described above, and among them, isophorone diisocyanate, xylylene-1,4-diisocyanate, and xylylene-1,3-diisocyanate are more preferable.
Examples of the tri- or higher functional polyol compound used for the production of the microgel (2) include glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, sorbitol, , 2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol and the like.
In addition to the above, examples of the trifunctional or higher functional phenol compound include a compound having three or more phenolic hydroxyl groups in one aromatic ring, a compound having three or more aromatic rings having one phenolic hydroxyl group, and the like.
As the monofunctional alcohol compound used for the production of the microgel (2), a monofunctional alcohol compound having a low solubility in an aqueous phase and having 8 or more carbon atoms is preferable. Moreover, as a monofunctional alcohol compound, a polyalkylene glycol monoalkyl ether compound is mentioned preferably, A polyethylene glycol monoalkyl ether or a polypropylene glycol monoalkyl ether is mentioned more preferably.

The average primary particle size of the polymer particles is preferably 0.01 to 5.0 μm, more preferably 0.05 to 4.0 μm, still more preferably 0.10 to 3.0 μm, and 0.10 to 1.0 μm. Particularly preferred.
The content of the metathesis catalyst in the polymer particles is preferably 0.001 to 1% by mass with respect to the total mass of the polymer particles, from the viewpoint of ease of synthesis into microgel and engraving sensitivity, More preferably, it is 0.5 mass%, and it is still more preferable that it is 0.01-0.1 mass%.
Moreover, it is preferable that content of the component A is 0.1-60 mass% with respect to the total solid of a resin composition from a viewpoint of printing durability and engraving sensitivity, and it is 1-40 mass%. Is more preferable, and it is still more preferable that it is 5-30 mass%.

(Component B) Polymer having an ethylenically unsaturated group The resin composition for laser engraving of the present invention contains (Component B) a polymer having an ethylenically unsaturated group (hereinafter also referred to as “binder polymer”).
Component B is preferably a polymer having monomer units derived from conjugated dienes such as butadiene and isoprene.
Component B is preferably a polymer selected from the group consisting of a polymer having a polybutadiene structure, a polymer having a polyisoprene structure, and urethane (meth) acrylate.
Component B is preferably a water-insoluble polymer.

Component B has an ethylenically unsaturated bond in at least one portion selected from the group consisting of the inside of the main chain, the main chain end and the side chain, and at least one selected from the group consisting of the inside of the main chain and the main chain end The portion preferably has an ethylenically unsaturated bond, and more preferably has at least one portion inside the main chain having an ethylenically unsaturated bond.
In the present invention, “main chain” represents a relatively long bond chain in the molecule of the polymer compound constituting the resin, and “side chain” represents a carbon chain branched from the main chain. The side chain may contain a hetero atom.
The ethylenically unsaturated group that Component B may have is not particularly limited, but is preferably an ethylenically unsaturated bond derived from butadiene or isoprene, or a (meth) acryl group, and butadiene. Alternatively, an ethylenically unsaturated bond derived from isoprene or a (meth) acryloxy group is more preferable, and an ethylenically unsaturated bond derived from butadiene or isoprene is still more preferable.
Moreover, as an ethylenically unsaturated bond derived from butadiene or isoprene, an ethylenically unsaturated bond inside the main chain formed by 1,4-addition, a side formed by 1,2-addition or 3,4-addition The ethylenically unsaturated bonds of the chain and ethylenically unsaturated compounds in which these ethylenically unsaturated bonds are regioisomerized may be used, but component B is formed by 1,4-addition of butadiene or isoprene. It is preferable to have at least an ethylenically unsaturated bond inside the main chain.

  Component B is preferably a polymer selected from the group consisting of polybutadiene, polyisoprene, a copolymer obtained by copolymerizing at least butadiene and / or isoprene, and urethane (meth) acrylate, and includes polybutadiene, polyisoprene, and More preferably, the polymer is selected from the group consisting of a copolymer obtained by copolymerizing at least butadiene and / or isoprene, more preferably a polymer selected from the group consisting of polybutadiene and polyisoprene. It is particularly preferred. In the above embodiment, a flexographic printing plate excellent in printing durability and ink transfer property is obtained, and the engraving residue rinsing property is excellent.

Component B is preferably a plastomer at 20 ° C. In the above embodiment, both strength and flexibility can be achieved, and when crosslinking is performed, the fluidity is excellent and sufficient crosslinking can be performed, so that the printing durability and image quality of the flexographic printing plate can be improved. Excellent rinsability.
In the present invention, “plastomer” means that it is easily deformed by heating and deformed by cooling, as described in “New edition polymer dictionary” edited by the Society of Polymer Science, Japan (Asakura Shoten, published in 1988). It means a polymer having the property that it can be solidified into a shaped shape. Plastomer is a term for an elastomer (having the property of instantly deforming according to the external force when an external force is applied and restoring the original shape in a short time when the external force is removed). It does not show such elastic deformation and easily plastically deforms.
In the present invention, when the original size is 100%, the plastomer can be deformed to 200% with a small external force at room temperature (20 ° C.) and does not return to 130% or less even when the external force is removed. Means things. The small external force specifically refers to an external force having a tensile strength of 1 to 100 MPa. More specifically, based on the tensile permanent strain test of JIS K 6262-1997, the distance between the marked lines before tension of the dumbbell-shaped No. 4 test piece specified in JIS K 6251-1993 in the tensile test at 20 ° C. is 2 It can be stretched without breaking twice, and after holding for 60 minutes when stretched to twice the distance between the marked lines before tension, the tensile permanent strain is 30% or more after 5 minutes excluding the tensile external force Means a polymer. In the present invention, all of the test pieces are JIS K 6262 except that the test piece is made into a dumbbell shape defined in JIS K 6251, the holding time is 60 minutes, and the temperature of the test chamber is 20 ° C. According to the 1997 tensile set test method.

In the case of a polymer that cannot be measured as described above, that is, in a tensile test, a polymer that does not return to its original shape even if a tensile external force is not applied, or a polymer that breaks by applying a small external force at the time of measurement corresponds to a plastomer. To do. For example, a polymer that is liquid at 20 ° C. is a plastomer.
Furthermore, the plastomer may be judged from the glass transition temperature (Tg) of the polymer being less than 20 ° C. In the case of a polymer having two or more Tg, all Tg is less than 20 ° C. The Tg of the polymer can be measured by a differential scanning calorimetry (DSC) method.

A polymer having a polybutadiene structure or a polymer having a polyisoprene structure may be a butadiene or isoprene homopolymer or a copolymer obtained by copolymerizing butadiene and / or isoprene. It may be a polymer.
In addition, a polymer having a polybutadiene structure or a polymer having a polyisoprene structure may be a polymer having a main chain mainly composed of isoprene or butadiene as a monomer unit, and a part thereof is hydrogenated to be converted to a saturated bond. It may be. In addition, the main chain or the terminal of the polymer may be modified with an amide, a carboxy group, a hydroxy group, a (meth) acryloyl group or the like, or may be epoxidized.
The copolymerizable monomer is not particularly limited, and examples thereof include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, acrylamide, methacrylamide, and meta. Examples include vinyl acrylamide, acrylic acid ester, methacrylic acid ester, acrylic acid, and methacrylic acid.

Specific examples of the copolymer obtained by copolymerizing at least butadiene and / or isoprene include styrene-butadiene copolymer, styrene-isoprene polymer, acrylonitrile-butadiene copolymer, acrylonitrile-isoprene copolymer, acrylate ester- Butadiene copolymer, acrylic ester-isoprene copolymer, acrylic ester-chloroprene copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer Copolymer, terminal (meth) acrylate modified polybutadiene, terminal (meth) acrylate modified polyisoprene, terminal (meth) acrylate modified hydrogenated polybutadiene, terminal (meth) acrylate modified hydrogenated polyisoprene, etc. And the like.
The polymer having a polybutadiene structure and the polymer having a polyisoprene structure may be produced by emulsion polymerization or may be produced by solution polymerization.

In the present invention, the polymer having a polybutadiene structure and the polymer having a polyisoprene structure have a proportion of monomer units derived from aliphatic hydrocarbons (isoprene, butadiene, or hydrogenated products thereof) in the main chain of 80 mol%. The above is preferable. It is preferable for the proportion of monomer units derived from aliphatic hydrocarbons in the main chain to be 80 mol% or more because the rinsing properties are good. The content of the monomer unit derived from the aliphatic hydrocarbon is more preferably 90 mol% or more of the total monomer units constituting the main chain of the component A, still more preferably 95 mol%, and more preferably 99 mol% or more. It is particularly preferred.
That is, for example, in the polymer having a polyisoprene structure, the ratio of the monomer units derived from the hydrogenated product of isoprene and isoprene is preferably 80 mol% or more in total, more preferably 90 mol% or more, More preferably, it is 95 mol% or more, and it is especially preferable that it is 99 mol% or more.
Similarly, in the polymer having a polybutadiene structure, the proportion of monomer units derived from the hydrogenated product of butadiene and butadiene is preferably 80 mol% or more in total, more preferably 90 mol% or more, and 95 mol%. More preferably, it is more preferably 99 mol% or more.
Further, when isoprene or butadiene copolymer is used as Component A, it is preferable that the monomer units derived from isoprene, butadiene and their hydrogenated substances are contained in a total of 80 mol% or more, preferably 90 mol% or more. More preferably, it is more preferably 95 mol% or more, and particularly preferably 99 mol% or more.

Isoprene is known to polymerize by 1,2-, 3,4-, or 1,4-addition, depending on the catalyst and reaction conditions, but the present invention is not limited to polyisoprene polymerized by any of the above additions. Good. Among these, from the viewpoint of obtaining a desired Mooney viscosity, it is preferable to contain cis-1,4-polyisoprene as a main component. The content of cis-1,4-polyisoprene is preferably 50% by mass or more, more preferably 65% by mass or more, still more preferably 80% by mass or more, and 90% by mass. The above is particularly preferable.
Moreover, as a polyisoprene, the commercially available polyisoprene can also be used, for example, a NIPOL IR series (made by Nippon Zeon Co., Ltd.) is illustrated.

Butadiene is known to be polymerized by 1,2- or 1,4-addition depending on the catalyst and reaction conditions, but the present invention may be polybutadiene polymerized by any of the above additions. Among these, it is more preferable that 1,4-polybutadiene is a main component from the viewpoint of obtaining a desired Mooney viscosity.
The content of 1,4-polybutadiene is preferably 50% by mass or more, more preferably 65% by mass or more, further preferably 80% by mass or more, and 90% by mass or more. It is particularly preferred.
The content of the cis body and the trans body is not particularly limited and may be appropriately selected within the range of a desired viscosity or Mooney viscosity. From the viewpoint of developing rubber elasticity after crosslinking, a cis body is preferable, and cis- The content of 1,4-polybutadiene is preferably 50% by mass or more, more preferably 65% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more. preferable.
A commercially available product may be used as the polybutadiene, and examples thereof include the NIPOL BR series (manufactured by ZEON Corporation), the UBEPOL BR series (manufactured by Ube Industries, Ltd.), and the like.

Examples of the liquid polybutadiene include commercially available products such as Claprene LBR-305 (manufactured by Kuraray Co., Ltd.) and Ricon (manufactured by Sartomer).
Examples of the liquid polyisoprene include Claprene LIR-30 and LIR-50 (manufactured by Kuraray Co., Ltd.).
Examples of the polyisoprene having a (meth) acrylate group include methacrylate-introduced polyisoprene (Kuraprene US-203, UC-102, manufactured by Kuraray Co., Ltd.).
Moreover, as a polybutadiene which has an ethylenically unsaturated group at the terminal, (meth) acrylate group introduction | transduction polybutadiene (NISSO-PB TEAI-1000, EA-3000, Nippon Soda Co., Ltd. product) is mentioned, for example.

Among these, as the polymer having a polybutadiene structure and the polymer having a polyisoprene structure, polyisoprene, polybutadiene, styrene-isoprene-styrene block copolymer, or styrene-butadiene-styrene block copolymer is more preferable. Polyisoprene or polybutadiene is particularly preferable.
Component A is preferably polybutadiene or polyisoprene, and particularly preferably polybutadiene, from the viewpoints of printing durability of flexographic printing plates, rinsing properties of engraving residue, and handling.

  Urethane (meth) acrylate is a polyurethane resin having a (meth) acryloxy group in the main chain, main chain terminal or side chain, and includes aliphatic urethane (meth) acrylate and aromatic urethane (meth) acrylate. It is done. For details, refer to the oligomer handbook (supervised by Junji Furukawa, Chemical Daily Co., Ltd.).

  The urethane (meth) acrylate preferably has at least one bond selected from the group consisting of a carbonate bond and an ester bond in the molecule. When the urethane (meth) acrylate has the above bond, resistance of the printing plate to an ink cleaning agent containing an ester solvent used in printing or an ink cleaning agent containing a hydrocarbon solvent is improved.

Examples of the diol compound having a carbonate bond used for the production of a polyurethane resin having a hydroxyl group include fats such as 4,6-polyalkylene carbonate diol, 8,9-polyalkylene carbonate diol, and 5,6-polyalkylene carbonate diol. Group polycarbonate diol and the like. Further, polycarbonate diol having an aromatic ring may be used.
The terminal hydroxyl groups of these compounds are tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tetramethylxylene diisocyanate, xylene diisocyanate, naphthalene diisocyanate, trimethylhexamethylene diisocyanate, p-phenylene diisocyanate, cyclohexylene. Diisocyanate compounds such as diisocyanate, lysine diisocyanate, triphenylmethane diisocyanate, triphenylmethane triisocyanate, 1-methylbenzene-2,4,6-triisocyanate, naphthalene-1,3,7-triisocyanate, biphenyl-2,4 , 4'-Triisocyanate A urethane bond can be introduced by a condensation reaction of a polyisocyanate compound such as a cyanate compound.

  Urethane (meth) acrylates are commercially available products such as, for example, the UV-3200, UV-3000B, UV-3700B, UV-3210EA, UV-2000B, and UV-3630ID80 (manufactured by Nippon Synthetic Chemical Co., Ltd.). , EBECRYL230, EBECRYL9227EA (above, Daicel Cytec Co., Ltd.), Hicorp AU series AU-3040, AU-3050, AU-3090, AU-3110, AU-3120 (above, manufactured by Tokushi Co., Ltd.) be able to.

As another method for obtaining urethane (meth) acrylate and the like, there is also a method of producing a polyurethane by polyaddition reaction of the aforementioned polyisocyanate compound and a diol compound having a (meth) acryloxy group.
Preferred examples of the diol compound having a (meth) acryloxy group used in this case include Blemma-GLM manufactured by NOF Corporation, DA-212, DA-212 of "Denacol Acrylate" series manufactured by Nagase ChemteX Corporation. -250, DA-721, DA-722, DA-911M, DA-920, DA-931, DM-201, DM-811, DM-832, DM-851 and the like.

  Moreover, as a component B, an ethylene-propylene-diene copolymer can also be illustrated preferably. As the copolymer, an ethylene-propylene-5-ethylidene-2-norbornene copolymer is more preferable.

The molecular weight of Component B is a weight average molecular weight (GPC, converted to polystyrene), preferably 1,000 or more, more preferably 10,000 or more, still more preferably 100,000 or more, 500 000 or more is particularly preferable. The molecular weight of Component B is preferably 3,000,000 or less, more preferably 2,000,000 or less, and 1,500,000 or less in terms of weight average molecular weight (GPC, polystyrene conversion). More preferably. Within the above range, processing of the resin composition for laser engraving is easy, and the printing durability of the resulting flexographic printing plate is excellent. Moreover, the effect of this invention accompanying the decomposition | disassembly of the polymer by a metathesis catalyst can be more exhibited as Mw of the component B is 500,000 or more.
In the present invention, the weight average molecular weight and the number average molecular weight are measured by a gel permeation chromatography method (GPC) method and are calculated by standard polystyrene. Specifically, for example, GPC uses HLC-8220GPC (manufactured by Tosoh Corporation), and TSKgeL SuperHZM-H, TSKgeL SuperHZ4000, TSKgeL SuperHZ2000 (4.6 mm ID × 15 cm, manufactured by Tosoh Corporation) are used as columns. Three are used and THF (tetrahydrofuran) is used as an eluent. As conditions, the sample concentration is 0.35% by mass, the flow rate is 0.35 ml / min, the sample injection amount is 10 μl, the measurement temperature is 40 ° C., and an IR detector is used. In addition, the calibration curve is “standard sample TSK standard, polystyrene” manufactured by Tosoh Corporation: “F-40”, “F-20”, “F-4”, “F-1”, “A-5000”, It is prepared from 8 samples of “A-2500”, “A-1000”, “n-propylbenzene”.

In the present invention, the Mooney viscosity of Component B is not particularly limited, but is preferably 90 or less, more preferably 70 or less, and 60 or less, from the viewpoint of solvent solubility and ease of handling during mixing. More preferably. Further, the lower limit value of the Mooney viscosity is not particularly limited, and for example, the component B may be in a liquid or syrupy state.
In the present invention, the Mooney viscosity is a value measured in accordance with JIS 6300-1. Specifically, a cylindrical space is formed between dies capable of temperature control to form a sample chamber, a rotor is disposed in the center of the sample chamber, and a sample to be measured is filled into the sample chamber. While maintaining the temperature at a predetermined temperature, the rotor is rotated at a specified rotational speed, and the rotor counter torque generated by the viscous resistance of the molten sample is detected by a load cell. The Mooney viscosity value used in the present invention is an L-shaped rotor, the preheating time is 1 minute, the rotor rotation time is 4 minutes, and the Mooney viscosity of the rubber sample is rotated at 100 ° C. with a preheating period of 1 minute. The Mooney viscosity (ML _{1 + 4} ) after 4 minutes is shown.

  The content of Component B is preferably 50 to 95% by mass, more preferably 55 to 90% by mass, and 65 to 90% by mass with respect to the total mass of the resin composition for laser engraving. Is more preferable, and it is especially preferable that it is 70-85 mass%. When the content of component B is in the above range, a relief layer having excellent engraving residue rinsing properties and excellent ink transfer properties can be obtained.

The resin composition for laser engraving of the present invention may contain a polymer other than Component B, that is, a polymer having no ethylenically unsaturated bond. Examples of the polymer other than Component B include non-elastomers described in JP2011-136455A, unsaturated group-containing polymers described in JP2010-208326A, and JP2012-45801A. Examples thereof include the binder polymers described in paragraphs 0009 to 0030.
Examples thereof include hydrogenated polybutadiene and hydrogenated polyisoprene.
When the resin composition for laser engraving of the present invention contains other polymer in addition to Component B, it is preferably 30% by mass or less, and preferably 10% by mass or less, based on the total mass of the resin composition for laser engraving. Is more preferably 5% by mass or less, particularly preferably 2% by mass or less, and most preferably 0% by mass, that is, not containing. Within the above range, a relief layer having excellent engraving residue rinsing properties and excellent ink transfer properties can be obtained.

(Component C) Crosslinking Agent The resin composition for laser engraving of the present invention preferably contains (Component C) a crosslinking agent.
As a crosslinking agent, a peroxide, a vulcanizing agent, and a polymerization initiator are mentioned preferably, and a peroxide is mentioned more preferably. Moreover, it is preferable to use together a polymerization initiator with the polymeric compound mentioned later.
In the case of containing a peroxide, since the peroxide is highly reactive, not only the polymerization of ethylenically unsaturated groups but also the extraction of hydrogen atoms bonded to saturated carbon atoms of saturated hydrocarbon chains to generate carbon radicals. , Carbon atom-carbon atom bridges can be formed.

Examples of peroxides include inorganic peroxides and organic peroxides, with organic peroxides being preferred.
Preferred organic peroxides include dialkyl peroxides, peroxyketals, peroxyesters, diacyl peroxides, alkyl hydroperoxides, peroxydicarbonates, ketone peroxides, dialkyl peroxides, peroxyketals, and More preferably, the organic peroxide is selected from the group consisting of peroxyesters.
Dialkyl peroxides include di-t-butyl peroxide, di-t-hexyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α, α′-bis (t-butylperoxy) diisopropylbenzene, Examples include 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane and 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3.
As peroxyketals, n-butyl-4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane, 1,1-bis (t-butylperoxy) Cyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) Examples include -3,3,5-trimethylcyclohexane.

Peroxyesters include α-cumylperoxyneodecanoic acid, 1,1-dimethyl-3-hydroxybutylperoxy-2-ethylhexanoic acid, t-amylperoxybenzoate, t-butylperoxypivalic acid, 3, 3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (t-amylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′- Tetra (t-hexylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (t-octylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (cumylperoxycarbonyl) benzophenone 3,3 ′, 4,4′-tetra (p-isopropylcumylperoxycarbonyl) benzophenone, di-t-butyl Peroxyisophthalate, di-t-butyldiperoxyisophthalate, t-butylperoxybenzoate, t-butylperoxy-3-methylbenzoate, t-butylperoxylaurate, t-butylperoxypivalate, t-butylperoxy-2-ethylhexanoate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxyneoheptanoate, t-butylperoxyneodecanoate, t-butyl peroxyacetate, α, α′-di (t-butylperoxy) diisopropylbenzene, t-butylcumyl peroxide, di-t-butyl peroxide, t-butylperoxyisopropyl monocarbonate, t-butyl Peroxy-2-ethylhexyl monocarbonate is an example That.
Examples of organic peroxides include diacyl peroxides such as dibenzoyl peroxide, succinic acid peroxide, dilauroyl peroxide, and didecanoyl peroxide, and 2,5-dihydroperoxy-2,5-dimethyl. Hexane, cumene hydroperoxide, and alkyl hydroperoxides such as t-butyl hydroperoxide, di (n-propyl) peroxydicarbonate, di (sec-butyl) peroxydicarbonate, and di (2- Peroxydicarbonates such as ethylhexyl) peroxydicarbonate can also be used.
Among these, dicumyl peroxide is particularly preferable.
Organic peroxides are commercially available, and are commercially available from, for example, NOF Corporation and Kayaku Akzo Corporation.
(C) Organic peroxides preferable as a polymerization initiator that can be used in the present invention include 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4, 4'-tetra (t-amylperoxycarbonyl) benzophenone, 3,3 ', 4,4'-tetra (t-hexylperoxycarbonyl) benzophenone, 3,3', 4,4'-tetra (t-octyl) Peroxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (cumylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (p-isopropylcumylperoxycarbonyl) benzophenone, di-t -Butyl diperoxyisophthalate, di-t-butyldiperoxyisophthalate, t-butylperoxybenzoate, t-butylperoxy -3-methylbenzoate, t-butylperoxylaurate, t-butylperoxypivalate, t-butylperoxy-2-ethylhexanoate, t-butylperoxy-3,5,5-trimethylhexanoate Ate, t-butylperoxyneoheptanoate, t-butylperoxyneodecanoate, t-butylperoxyacetate, α, α'-di (t-butylperoxy) diisopropylbenzene, t-butylcumylper Peroxide esters such as oxide, di-t-butyl peroxide, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy-2-ethylhexyl monocarbonate are preferred.

  Inorganic peroxides include calcium peroxide, magnesium peroxide, strontium peroxide, barium peroxide, lithium peroxide, sodium peroxide, potassium peroxide, zinc peroxide, silver peroxide, copper peroxide, and iron peroxide. And lead peroxide. Among these, calcium peroxide, barium peroxide, sodium peroxide, and zinc peroxide are preferable, and calcium peroxide and zinc peroxide are particularly preferable.

Preferred examples of the vulcanizing agent include elemental sulfur (free sulfur) and a sulfur-donating organic vulcanizing agent, and more preferred is elemental sulfur.
As the sulfur-donating organic vulcanizing agent, morpholine disulfide, dithiodicaprolactam, alkylphenol disulfide, polymeric polysulfide and the like are used.
Commercially available products can also be used as vulcanizing agents, such as sulfur (manufactured by Tsurumi Chemical Co., Ltd.) and Barnock R (manufactured by Ouchi Shinsei Chemical Co., Ltd., morpholine disulfide). it can.

As the polymerization initiator, those known to those skilled in the art can be used without limitation. Hereinafter, although the radical polymerization initiator which is a preferable polymerization initiator is explained in full detail, this invention is not restrict | limited by these description.
Further, the above-described peroxide is also widely included in the polymerization initiator.
As the polymerization initiator, a radical polymerization initiator is preferable.
Moreover, as a polymerization initiator, it is preferable that it is a thermal polymerization initiator, and it is more preferable that it is a thermal radical polymerization initiator.

  In the present invention, preferred polymerization initiators include (a) aromatic ketones, (b) onium salt compounds, (c) organic peroxides, (d) thio compounds, (e) hexaarylbiimidazole compounds, f) ketoxime ester compounds, (g) borate compounds, (h) azinium compounds, (i) metallocene compounds, (j) active ester compounds, (k) compounds having a carbon halogen bond, (l) azo compounds, etc. Can be mentioned. Specific examples of the above (a) to (l) are given below, but the present invention is not limited to these.

(A) aromatic ketones, (b) onium salt compounds, (d) thio compounds, (e) hexaarylbiimidazole compounds, (f) ketoxime ester compounds, (g) borate compounds, (h) azinium compounds , (I) a metallocene compound, (j) an active ester compound, and (k) a compound having a carbon halogen bond, the compounds listed in paragraphs 0074 to 0118 of JP-A-2008-63554 are preferably used. Can do.
(C) As an organic peroxide, the compound mentioned above can be used preferably.
In addition, as the (l) azo compound, the following compounds are preferable.

(L) Azo-based compound Preferred as a polymerization initiator that can be used in the present invention (l) As the azo-based compound, 2,2′-azobisisobutyronitrile, 2,2′-azobispropionitrile, 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2 ′ -Azobis (4-methoxy-2,4-dimethylvaleronitrile), 4,4'-azobis (4-cyanovaleric acid), dimethyl 2,2'-azobisisobutyrate, 2,2'-azobis (2-methylpropion) Amidooxime), 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2 -Hydro Cyethyl] propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis (N-butyl-2-methylpropionamide), 2,2 '-Azobis (N-cyclohexyl-2-methylpropionamide), 2,2'-azobis [N- (2-propenyl) -2-methylpropionamide], 2,2'-azobis (2,4,4- Trimethylpentane) and the like.

Further, from the viewpoint of engraving sensitivity, an embodiment in which an organic peroxide and a (component D) photothermal conversion agent described later are combined is particularly preferable.
This is because when an organic peroxide is used to cure the relief forming layer by thermal crosslinking, unreacted organic peroxide that does not participate in radical generation remains, but the remaining organic peroxide is self-reactive. Works as an additive and decomposes exothermically during laser engraving. As a result, it is presumed that the engraving sensitivity is increased because the heat generated is added to the irradiated laser energy.
In addition, although explained in full detail in description of a photothermal conversion agent, this effect is remarkable when using carbon black as a photothermal conversion agent. This is because the heat generated from carbon black is transferred to the organic peroxide, which generates heat not only from carbon black but also from organic peroxide. Is considered to occur synergistically.

In the present invention, Component C may be used alone or in combination of two or more.
The content of component C contained in the resin composition for laser engraving of the present invention is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more with respect to the total mass of the resin composition. It is more preferable that the content is 0.5% by mass or more. The upper limit of the content of component B is not particularly limited, but is preferably 30% by mass or less, more preferably 20% by mass or less, and more preferably 10% by mass or less from the viewpoint of the blending amount of other components. More preferably. When the content is in the above range, a flexographic printing plate excellent in printing durability and ink transfer property can be obtained, and the engraving residue rinsing property is excellent.

(Component D) Photothermal Conversion Agent The resin composition for laser engraving of the present invention preferably further contains (Component D) a photothermal conversion agent. That is, it is considered that the photothermal conversion agent in the present invention promotes thermal decomposition of a cured product during laser engraving by absorbing laser light and generating heat. For this reason, it is preferable to select a photothermal conversion agent that absorbs light having a laser wavelength used for engraving.

A laser engraving type flexographic printing plate precursor produced using the resin composition for laser engraving of the present invention is irradiated with a laser (YAG laser, semiconductor laser, fiber laser, surface emitting laser, etc.) emitting infrared rays of 700 to 1,300 nm. As the photothermal conversion agent, it is preferable to use a compound having a maximum absorption wavelength at 700 to 1,300 nm.
Various dyes or pigments are used as the photothermal conversion agent in the present invention.

  Among the photothermal conversion agents, as the dye, commercially available dyes and known ones described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specific examples include those having a maximum absorption wavelength at 700 to 1,300 nm, such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, diimmonium compounds, and quinoneimine dyes. Preferred are dyes such as methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes. Dyes preferably used in the present invention include cyanine dyes such as heptamethine cyanine dyes, oxonol dyes such as pentamethine oxonol dyes, phthalocyanine dyes, and paragraphs 0124 to 0137 of JP-A-2008-63554. Mention may be made of dyes.

Among the photothermal conversion agents used in the present invention, commercially available pigments and color index (CI) manuals, “latest pigment manuals” (edited by the Japan Pigment Technical Association, published in 1977), “latest pigment application” The pigments described in “Technology” (CMC Publishing, 1986) and “Printing Ink Technology” CMC Publishing, 1984) can be used. Examples of the pigment include pigments described in paragraphs 0122 to 0125 of JP-A-2009-178869.
Of these pigments, carbon black is preferred.

  As long as the dispersibility in the composition is stable, carbon black can be used regardless of the classification according to ASTM or the use (for example, for color, for rubber, for dry battery, etc.). Carbon black includes, for example, furnace black, thermal black, channel black, lamp black, acetylene black and the like. In order to facilitate dispersion, black colorants such as carbon black can be used as color chips or color pastes previously dispersed in nitrocellulose or a binder, if necessary. Such chips and pastes can be easily obtained as commercial products. Examples of carbon black include those described in paragraphs 0130 to 0134 of JP2009-178869A.

Only 1 type may be used for the photothermal conversion agent in the resin composition of this invention, and it may use 2 or more types together.
The content of the photothermal conversion agent in the resin composition for laser engraving varies greatly depending on the molecular extinction coefficient inherent to the molecule, but is preferably 0.01 to 30% by mass with respect to the total mass of the resin composition. 0.05 to 20% by mass is more preferable, and 0.1 to 10% by mass is particularly preferable.

(Component E) Polymerizable Compound The resin composition for laser engraving of the present invention may further contain (Component E) a polymerizable compound in order to promote the formation of a crosslinked structure, but it is preferably not contained.
Component E is a polymerizable compound other than Component B.
Furthermore, Component E is preferably a compound having a molecular weight of less than 3,000, more preferably a compound having a molecular weight of less than 2,000, and even more preferably a compound having a molecular weight of less than 1,000.
Component E is preferably a radically polymerizable compound, and is preferably an ethylenically unsaturated compound.

The polymerizable compound that can be used in the present invention is preferably a polyfunctional polymerizable compound, and more preferably a polyfunctional ethylenically unsaturated compound. In the above embodiment, the resin composition is excellent in curability, and a flexographic printing plate having excellent printing durability can be obtained.
The polyfunctional ethylenically unsaturated compound that can be used in the present invention preferably has a molecular weight (or weight average molecular weight) of less than 2,000.
The polyfunctional ethylenically unsaturated compound is a compound having two or more ethylenically unsaturated groups. A polyfunctional ethylenically unsaturated compound may be used individually by 1 type, and may use 2 or more types together.
Moreover, the compound group which belongs to an ethylenically unsaturated compound is widely known in this industry field, and can use these without a restriction | limiting in particular in this invention. These have chemical forms such as monomers, prepolymers, i.e. dimers, trimers and oligomers, or copolymers thereof, and mixtures thereof.
A polyfunctional monomer is preferably used as the polyfunctional ethylenically unsaturated compound. The molecular weight of these polyfunctional monomers (when having a molecular weight distribution, the weight average molecular weight) is preferably 200 or more and less than 2,000, more preferably 200 to 1,000, and 200 to 700. More preferably it is.

As the polyfunctional monomer, a compound having 2 to 20 terminal ethylenically unsaturated groups is preferable.
Examples of the polyfunctional monomer include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters and amides thereof. Esters of saturated carboxylic acids and aliphatic polyhydric alcohol compounds, and amides of unsaturated carboxylic acids and aliphatic polyvalent amine compounds are used. Also, unsaturated carboxylic acid esters having nucleophilic substituents such as hydroxyl groups and amino groups, amides and polyfunctional isocyanates, addition reaction products of epoxies, dehydration condensation reaction products of polyfunctional carboxylic acids Etc. are also preferably used. Further, unsaturated carboxylic acid esters having an electrophilic substituent such as isocyanato group, epoxy group, etc., addition reaction products of amides with monofunctional or polyfunctional alcohols, amines, halogen groups, tosyloxy A substitution reaction product of an unsaturated carboxylic acid ester or amide with a monofunctional or polyfunctional alcohol or amine having a leaving substituent such as a group is also suitable. As another example, a compound group in which a vinyl compound, an allyl compound, an unsaturated phosphonic acid, styrene, or the like is substituted for the above unsaturated carboxylic acid can be used.

  The ethylenically unsaturated group contained in the polyfunctional monomer is preferably an acrylate, methacrylate, vinyl compound, or allyl compound residue from the viewpoint of reactivity, and particularly preferably acrylate or methacrylate.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, 1, 3 -Butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, 1 , 4-Cyclohexanediol diacrylate, tetraethylene glycol diacrylate, polytetramethyl Glycol diacrylate, 1,8-octanediol diacrylate, 1,9-nonanediol diacrylate, 1,10-decanediol diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate, trimethylolpropane triacrylate (Acryloyloxypropyl) ether, ditrimethylolpropane tetraacrylate, trimethylolethane triacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, Sorbitol tetraacrylate, sorbitol pentaacrylate Sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, propylene glycol dimethacrylate, dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate, polypropylene Glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,8-octanediol dimethacrylate, 1 , 9-Nonanediol dimethacryl 1,10-decanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p -(3-Methacryloxy-2-hydroxypropoxy) phenyl] dimethylmethane, bis [p- (methacryloxyethoxy) phenyl] dimethylmethane and the like.

Examples of other esters include aliphatic alcohol esters described in JP-B-46-27926, JP-B-51-47334, JP-A-57-196231, JP-A-59-5240, Those having an aromatic skeleton described in JP-A-59-5241 and JP-A-2-226149 and those containing an amino group described in JP-A-1-165613 are also preferably used.
The ester monomers can also be used as a mixture.

Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bisacrylamide, methylene bismethacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. Examples include methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, and xylylene bismethacrylamide.
Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B No. 54-21726.

In addition, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable, and specific examples thereof include, for example, one molecule described in JP-B-48-41708. A vinylurethane compound containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following formula (i) to a polyisocyanate compound having two or more isocyanate groups. Etc.
_{CH 2 = C (R) COOCH} 2 CH (R ') OH (i)
(However, R and R ′ each represent H or CH _3. )

Further, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-B-58-49860, JP-B-56-17654 Urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418 are also suitable.
Further, by using addition-polymerizable compounds having an amino structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238, short A resin composition that cures over time can be obtained.

  Other examples include reacting polyester acrylates, epoxy resins and (meth) acrylic acid as described in JP-A-48-64183, JP-B-49-43191 and JP-B-52-30490. And polyfunctional acrylates and methacrylates such as epoxy acrylates. Further, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337, JP-B-1-40336, and vinylphosphonic acid compounds described in JP-A-2-25493 are also included. be able to. In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, the Japan Adhesion Association magazine vol. 20, no. 7, pages 300 to 308 (1984), which are introduced as photocurable monomers and oligomers, can also be used.

Monofunctional polymerizable compounds having only one ethylenically unsaturated group include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid and their salts, ethylenically unsaturated Group-containing anhydrides, (meth) acrylates, (meth) acrylamides, (meth) acrylonitriles, styrenes, various unsaturated polyester resins, unsaturated polyether resins, unsaturated polyamide resins, unsaturated urethanes Examples thereof include polymerizable compounds such as resins.
In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having an nucleophilic substituent such as a hydroxyl group, an amino group or a mercapto group and an isocyanate or an epoxy, and a monofunctional or polyfunctional carboxylic acid A dehydration condensation reaction product or the like is also preferably used.

Furthermore, addition reaction products of unsaturated carboxylic acid esters or amides having an electrophilic substituent such as an isocyanato group or an epoxy group with alcohols, amines or thiols, and further elimination of a halogeno group or a tosyloxy group. A substitution reaction product of an unsaturated carboxylic acid ester or amide having a releasing substituent with alcohols, amines or thiols is also suitable.
As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.
There is no restriction | limiting in particular as a polymeric compound, In addition to the compound illustrated above, well-known various compounds can be used, For example, you may use the compound etc. which are described in Unexamined-Japanese-Patent No. 2009-204962.

Furthermore, as monofunctional ethylenically unsaturated compounds, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, butoxyethyl (Meth) acrylate, carbitol (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, N-methylol (meth) acrylamide, (meth) acrylic acid derivatives such as epoxy (meth) acrylate, N-vinylpyrrolidone N-vinyl compounds such as N-vinylcaprolactam and derivatives of allyl compounds such as allyl glycidyl ether, diallyl phthalate and triallyl trimellitate are preferably used.
Among these, as a polyfunctional ethylenically unsaturated compound, a monofunctional (meth) acrylate compound (monofunctional (meth) acrylic acid ester) is preferable.

Among these, component E is preferably an acrylate (acrylic ester compound) or methacrylate (methacrylic ester compound), and particularly preferably an ester of an aliphatic polyhydric alcohol and acrylic acid or methacrylic acid. . Component E preferably has 2 to 20 (meth) acryloyloxy groups in one molecule, more preferably 2 to 8, more preferably 2 to 6, and more preferably 2 to 4. Particularly preferred.
Among these, component E is hexanediol di (meth) acrylate, decanediol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, and dipentaerythritol hexa (meth). ) It is preferred to contain at least one compound selected from the group consisting of acrylates.

When the resin composition for laser engraving contains the component E, the content of the component E contained in the resin composition for laser engraving is preferably 1 to 50% by mass with respect to the total mass of the resin composition. -40 mass% is more preferable, and 5-30 mass% is still more preferable. Within the above range, the relief forming layer comprising the resin composition for laser engraving is excellent in printing durability.
Further, from the viewpoint of improving the printing durability and suppressing the amount of engraving residue, the content of the component E contained in the resin composition for laser engraving is 10 to 50 mass relative to the total mass of the resin composition. % Is preferred.

  Hereinafter, in addition to Component A to Component E, various components that can be contained in the resin composition for laser engraving of the present invention will be described.

<Solvent>
In preparing the resin composition for laser engraving of the present invention, a solvent may be used, but it is preferably not used.
As the solvent, an organic solvent is preferably used.
Preferred specific examples of the aprotic organic solvent include acetonitrile, tetrahydrofuran, dioxane, toluene, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl isobutyl ketone, ethyl acetate, butyl acetate, ethyl lactate, N, N-dimethylacetamide, N -Methylpyrrolidone, dimethyl sulfoxide are mentioned.
Preferable specific examples of the protic organic solvent include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 1-methoxy-2-propanol, ethylene glycol, diethylene glycol, and 1,3-propanediol.
Among these, propylene glycol monomethyl ether acetate is particularly preferable.
The content of the solvent in the resin composition for laser engraving of the present invention is preferably 10% by mass or less, more preferably 1% by mass or less, based on the total mass of the resin composition. It is more preferable that the content is not more than mass%, and it is particularly preferable that the content is not contained.

<Other additives>
In the resin composition for laser engraving of the present invention, various known additives can be appropriately blended as long as the effects of the present invention are not impaired. Examples include plasticizers, fillers, waxes, process oils, metal oxides, antiozonants, antiaging agents, polymerization inhibitors, colorants, etc., and these may be used alone. Two or more kinds may be used in combination.

(Laser engraving type flexographic printing plate precursor and its manufacturing method)
The first embodiment of the laser engraving-type flexographic printing plate precursor of the present invention has a relief forming layer made of the resin composition for laser engraving of the present invention.
The second embodiment of the laser engraving-type flexographic printing plate precursor of the present invention has a crosslinked relief forming layer obtained by crosslinking the layer made of the resin composition for laser engraving of the present invention.
In the present invention, the “laser engraving type flexographic printing plate precursor” means that the relief forming layer having a crosslinkable property composed of a resin composition for laser engraving is crosslinked by light and / or heat before being crosslinked. It refers to both or either state.
In the present invention, the “relief-forming layer” refers to a layer in a state before being crosslinked, that is, a layer made of the resin composition for laser engraving of the present invention, and may be dried if necessary. Good.
A “flexographic printing plate” is produced by laser engraving a printing plate precursor having a crosslinked relief forming layer.
In the present invention, the “crosslinked relief forming layer” refers to a layer obtained by crosslinking the relief forming layer. The cross-linking can be performed by heat and / or light. The cross-linking is not particularly limited as long as the resin composition is cured, and examples thereof include a cross-linked structure by reaction of Component B and Component C.
In the present invention, the “relief layer” refers to a layer engraved with a laser in a flexographic printing plate, that is, the crosslinked relief forming layer after laser engraving.

The laser engraving-type flexographic printing plate precursor of the present invention comprises a relief forming layer comprising a resin composition for laser engraving containing the above components, and a layer comprising a resin composition for laser engraving containing the above components. It has a crosslinked relief forming layer that has been crosslinked. The relief forming layer and the crosslinked relief forming layer are preferably provided on the support.
If necessary, the laser engraving-type flexographic printing plate precursor further comprises an adhesive layer between the support and the relief forming layer or the crosslinked relief forming layer, and a slip coat layer and a protective film on the relief forming layer or the crosslinked relief forming layer. You may have.

<Relief forming layer>
The relief forming layer is a layer made of the resin composition for laser engraving of the present invention, and is preferably a thermally crosslinkable layer.

  As a production mode of a flexographic printing plate using a laser engraving type flexographic printing plate precursor, a relief forming layer is crosslinked to form a flexographic printing plate precursor having a crosslinked relief forming layer, and then a crosslinked relief forming layer (hard relief forming layer) is used. A mode in which a relief layer is formed by laser engraving to produce a flexographic printing plate is preferred. By crosslinking the relief forming layer, abrasion of the relief layer during printing can be prevented, and a flexographic printing plate having a relief layer having a sharp shape after laser engraving can be obtained.

The relief forming layer can be formed by molding a resin composition for laser engraving having the above components for the relief forming layer into a sheet shape or a sleeve shape. The relief forming layer is usually provided on a support which will be described later. However, the relief forming layer can be directly formed on the surface of a member such as a cylinder provided in an apparatus for plate making and printing, or can be arranged and fixed there. It does not necessarily require a support.
Hereinafter, the case where the relief forming layer is formed into a sheet shape will be mainly described as an example.

<Support>
The material used for the support of the laser engraving type flexographic printing plate precursor is not particularly limited, but a material having high dimensional stability is preferably used. For example, a metal such as steel, stainless steel, aluminum, polyester (for example, PET (polyethylene terephthalate)) , Plastic resins such as PBT (polybutylene terephthalate), PAN (polyacrylonitrile)) and polyvinyl chloride, synthetic rubbers such as styrene-butadiene rubber, and plastic resins reinforced with glass fibers (such as epoxy resins and phenol resins) It is done. As the support, a PET film or a steel substrate is preferably used. The form of the support is determined depending on whether the relief forming layer is a sheet or a sleeve.

<Adhesive layer>
When the relief forming layer is formed on the support, an adhesive layer may be provided between the two for the purpose of enhancing the adhesive strength between the layers.
As a material (adhesive) that can be used for the adhesive layer, for example, I.I. Those described in the edition of Skeist, “Handbook of Adhesives”, the second edition (1977) can be used.

<Protective film, slip coat layer>
For the purpose of preventing scratches or dents on the surface of the relief forming layer or the surface of the crosslinked relief forming layer, a protective film may be provided on the surface of the relief forming layer or the surface of the crosslinked relief forming layer. The thickness of the protective film is preferably 25 to 500 μm, more preferably 50 to 200 μm. As the protective film, for example, a polyester film such as PET, or a polyolefin film such as PE (polyethylene) or PP (polypropylene) can be used. The surface of the film may be matted. The protective film is preferably peelable.

  When the protective film cannot be peeled or when it is difficult to adhere to the relief forming layer, a slip coat layer may be provided between both layers. The material used for the slip coat layer is composed mainly of a resin that is soluble or dispersible in water, such as polyvinyl alcohol, polyvinyl acetate, partially saponified polyvinyl alcohol, hydroxyalkyl cellulose, alkyl cellulose, and polyamide resin, and that is less sticky. It is preferable to do.

The method for producing the laser engraving-type flexographic printing plate precursor is not particularly limited. For example, a resin composition for laser engraving is prepared, and the solvent is removed from the coating solution composition for laser engraving as necessary. Then, a method of melt extrusion on a support can be mentioned. Alternatively, the resin composition for laser engraving may be cast on a support and dried in an oven to remove the solvent from the resin composition.
Among them, the method for producing a laser engraving-type flexographic printing plate precursor according to the present invention includes a step of forming a layer made of the resin composition for laser engraving of the present invention, and a cross-linking by cross-linking the layer made of the resin composition for laser engraving. It is preferable that it is a manufacturing method including the process of forming a relief forming layer.

Thereafter, a protective film may be laminated on the relief forming layer as necessary. Lamination can be performed by pressure-bonding the protective film and the relief forming layer with a heated calendar roll or the like, or by bringing the protective film into close contact with the relief forming layer impregnated with a small amount of solvent on the surface.
When using a protective film, you may take the method of laminating | stacking a relief forming layer on a protective film first, and laminating a support body then.
When providing an adhesive layer, it can respond by using the support body which apply | coated the adhesive layer. When providing a slip coat layer, it can respond by using the protective film which apply | coated the slip coat layer.

<Layer formation process>
The method for producing a laser engraving-type flexographic printing plate precursor of the present invention preferably includes a layer forming step of forming a relief forming layer comprising the resin composition for laser engraving of the present invention.
As a method for forming a relief forming layer, the resin composition for laser engraving of the present invention is prepared, a method of extruding rubber on a support, and a resin composition for laser engraving of the present invention are prepared, if necessary, After removing the solvent from the resin composition for laser engraving, a method of melt extrusion on a support, preparing the resin composition for laser engraving of the present invention, and applying the resin composition for laser engraving of the present invention on the support A method in which the solvent is removed by casting and drying in an oven is preferable.
Among them, it is preferable to form the relief forming layer by thermoforming such as a melt extrusion method, a rubber extrusion method, or a hot press method without using a solvent.
Moreover, it is preferable that the said layer formation process includes the process of knead | mixing the said resin composition for laser engravings, and the process of shape | molding the obtained kneaded material in a sheet form. Moreover, it is preferable that the process shape | molded into the said sheet form is a process shape | molded into a sheet form by hot press or extrusion.
The resin composition for laser engraving is, for example, a method in which component A and component B are mixed, and optional components and the like are sequentially mixed, or component A, component B, and optional components are dissolved or dispersed in an appropriate solvent. Then, although it can manufacture by the method of mixing component C etc. arbitrarily, the method which does not use a solvent is preferable. Since most of the solvent component is preferably removed at the stage of producing the flexographic printing plate precursor, the solvent is a low-molecular alcohol that easily volatilizes (for example, methanol, ethanol, n-propanol, isopropanol, propylene glycol monomethyl ether). It is preferable to keep the total amount of solvent added as small as possible by adjusting the temperature.

  The thickness of the (crosslinking) relief forming layer in the laser engraving-type flexographic printing plate precursor is preferably 0.05 mm or more and 10 mm or less, more preferably 0.05 mm or more and 7 mm or less, and more preferably 0.05 mm or more and 3 mm or less before and after crosslinking. Further preferred.

<Crosslinking process>
The method for producing a laser engraving-type flexographic printing plate precursor according to the present invention is a production method including a crosslinking step of crosslinking a layer comprising a resin composition for laser engraving to form a crosslinked relief forming layer.
In the crosslinking step, it is preferable to perform crosslinking with heat and / or light, and it is more preferable to perform crosslinking with heat.
The heating temperature in the crosslinking step can be arbitrarily set according to the decomposition temperature of the peroxide or the like, but is preferably 90 ° C. to 250 ° C., more preferably 100 ° C. to 180 ° C., 100 More preferably, the temperature is from 160 ° C to 160 ° C, particularly preferably from 120 ° C to 160 ° C. If it is the said aspect, bridge | crosslinking by a heat | fever can be performed easily simultaneously.
Examples of the heating means in the crosslinking step include a method of heating the printing plate precursor in a hot air oven or a far infrared oven for a predetermined time, or a method of contacting a heated roll for a predetermined time.

  In general, the light irradiation in the crosslinking step is performed on the entire surface of the relief forming layer. Examples of light (also referred to as “active light”) include visible light, ultraviolet light, and electron beam, with ultraviolet light being most preferred. If the substrate side for immobilizing the relief forming layer, such as the support of the relief forming layer, is the back side, the surface may only be irradiated with light, but the support should be a transparent film that transmits actinic rays. For example, it is preferable to irradiate light from the back side. When the protective film exists, the irradiation from the surface may be performed while the protective film is provided, or may be performed after the protective film is peeled off. Since polymerization inhibition may occur in the presence of oxygen, irradiation with actinic rays may be performed after the relief forming layer is covered with a polyvinyl chloride sheet and evacuated.

  Further, after the crosslinking step, the support may be peeled from the crosslinked relief forming layer, and from the viewpoint of strength and smoothness, after peeling the support provided during the crosslinking step from the crosslinked relief forming layer, You may provide another support body in the surface on the opposite side to the surface in which the said support body of the bridge | crosslinking relief forming layer was provided.

(Flexographic printing plate and plate making method)
The plate making method of the flexographic printing plate of the present invention preferably includes a preparation step of preparing the flexographic printing plate precursor of the present invention and an engraving step of laser engraving the flexographic printing plate precursor having the crosslinked relief forming layer.
The flexographic printing plate of the present invention is a flexographic printing plate having a relief layer obtained by crosslinking and laser engraving a layer comprising the resin composition for laser engraving of the present invention, and making the flexographic printing plate of the present invention. A flexographic printing plate made by the method is preferred.
As the preparation step in the plate making method of the flexographic printing plate of the present invention, the layer forming step and the crosslinking step are preferably mentioned. It is synonymous and the preferable range is also the same.

<Engraving process>
The plate making method of the flexographic printing plate of the present invention includes an engraving step of laser engraving the flexographic printing plate precursor having the crosslinked relief forming layer.
The engraving step is a step of forming a relief layer by laser engraving the crosslinked relief forming layer crosslinked in the crosslinking step. Specifically, it is preferable to form a relief layer by engraving a crosslinked crosslinked relief forming layer by irradiating a laser beam corresponding to a desired image. Moreover, the process of controlling a laser head with a computer based on the digital data of a desired image, and carrying out scanning irradiation with respect to a bridge | crosslinking relief forming layer is mentioned preferably.
In this engraving process, an infrared laser is preferably used. When irradiated with an infrared laser, the molecules in the crosslinked relief forming layer undergo molecular vibrations and generate heat. When a high-power laser such as a carbon dioxide laser or YAG laser is used as an infrared laser, a large amount of heat is generated in the laser irradiation part, and molecules in the crosslinked relief forming layer are selectively cut by molecular cutting or ionization. That is, engraving is performed. The advantage of laser engraving is that the engraving depth can be set arbitrarily, so that the structure can be controlled three-dimensionally. For example, a portion that prints fine halftone dots can be engraved shallowly or with a shoulder so that the relief does not fall down due to printing pressure, and a portion of a groove that prints fine punched characters is engraved deeply As a result, the ink is less likely to be buried in the groove, and it is possible to suppress the crushing of the extracted characters.
In particular, when engraving with an infrared laser corresponding to the absorption wavelength of the photothermal conversion agent, the crosslinked relief forming layer can be selectively removed with higher sensitivity, and a relief layer having a sharp image can be obtained.

As the infrared laser used in the engraving process, a carbon dioxide laser (CO ₂ laser) or a semiconductor laser is preferable from the viewpoints of productivity and cost. In particular, a semiconductor infrared laser with a fiber (FC-LD) is preferably used. In general, a semiconductor laser can be downsized with high efficiency and low cost of laser oscillation compared to a CO ₂ laser. Moreover, since it is small, it is easy to form an array. Furthermore, the beam shape can be controlled by processing the fiber.
The semiconductor laser preferably has a wavelength of 700 to 1,300 nm, more preferably 800 to 1,200 nm, still more preferably 860 to 1,200 nm, and particularly preferably 900 to 1,100 nm.

Moreover, since the semiconductor laser with a fiber can output a laser beam efficiently by attaching an optical fiber, it is effective for the engraving process in the present invention. Furthermore, the beam shape can be controlled by processing the fiber. For example, the beam profile can have a top hat shape, and energy can be stably given to the plate surface. Details of the semiconductor laser are described in “Laser Handbook 2nd Edition” edited by Laser Society, “Practical Laser Technology” edited by IEICE.
Also, a plate making apparatus equipped with a fiber-coupled semiconductor laser that can be suitably used in a method for making a flexographic printing plate using the flexographic printing plate precursor of the present invention is disclosed in JP 2009-172658 A and JP 2009-214334 A. It is described in detail in the official gazette and can be used for making a flexographic printing plate according to the present invention.

In the method for making a flexographic printing plate of the present invention, after the engraving step, the following rinsing step, drying step, and / or post-crosslinking step may be included as necessary.
Rinsing step: a step of rinsing the engraved surface of the relief layer surface after engraving with water or a liquid containing water as a main component.
Drying step: a step of drying the engraved relief layer.
Post-crosslinking step: a step of imparting energy to the relief layer after engraving and further crosslinking the relief layer.
Since the engraving residue is attached to the engraving surface after the above steps, a rinsing step of rinsing the engraving residue by rinsing the engraving surface with water or a liquid containing water as a main component may be added. As a means of rinsing, there is a method of washing with tap water, a method of spraying high-pressure water, and a known batch type or conveying type brush type washing machine as a photosensitive resin relief printing machine. For example, when the engraving residue cannot be removed, a rinsing liquid to which soap or a surfactant is added may be used.
When the rinsing process for rinsing the engraving surface is performed, it is preferable to add a drying process for drying the engraved relief forming layer and volatilizing the rinsing liquid.
Furthermore, you may add the post-crosslinking process which further bridge | crosslinks a relief forming layer as needed. By performing the post-crosslinking step, which is an additional cross-linking step, the relief formed by engraving can be further strengthened.

The rinsing liquid that can be used in the present invention is preferably a rinsing liquid having a pH of 8 to 14. In the above embodiment, the rinsing property of engraving residue generated during laser engraving is excellent.
Further, the pH of the rinsing solution that can be used in the present invention is more preferably 9 or more, further preferably 10 or more, and particularly preferably 11 or more. The pH of the rinse liquid is more preferably 13.5 or less, and further preferably 13.2 or less. When it is within the above range, handling is easy and the rinse property of engraving residue generated during laser engraving is excellent.
What is necessary is just to adjust pH using an acid and / or a base suitably in order to make a rinse liquid into said pH range, and the acid and base to be used are not specifically limited. From the viewpoint of cost and the like, the base is preferably an alkali metal or alkaline earth metal hydroxide.
The rinsing liquid that can be used in the present invention is preferably an aqueous rinsing liquid containing water as a main component.
Moreover, the rinse liquid may contain water miscible solvents, such as alcohol, acetone, tetrahydrofuran, etc. as solvents other than water.

It is preferable that the rinse liquid contains a surfactant.
As a surfactant that can be used in the present invention, a carboxybetaine compound, a sulfobetaine compound, a phosphobetaine compound, an amine oxide compound, or a viewpoint of reducing engraving residue removal and the influence on the flexographic printing plate Preferred are betaine compounds (amphoteric surfactants) such as phosphine oxide compounds.

Examples of the surfactant include known anionic surfactants, cationic surfactants, and nonionic surfactants. Furthermore, fluorine-based and silicone-based nonionic surfactants can be used in the same manner.
Surfactant may be used individually by 1 type, or may use 2 or more types together.
Although the usage-amount of surfactant does not need to specifically limit, it is preferable that it is 0.01-20 mass% with respect to the total mass of a rinse liquid, and it is more preferable that it is 0.05-10 mass%.

As described above, a flexographic printing plate having a relief layer on the surface of an arbitrary substrate such as a support can be obtained.
The thickness of the relief layer of the flexographic printing plate is preferably 0.05 mm or more and 10 mm or less, more preferably 0.05 mm or more and 7 mm, from the viewpoint of satisfying various printability such as abrasion resistance and ink transferability. Hereinafter, it is particularly preferably 0.05 mm or more and 3 mm or less.

Moreover, it is preferable that the Shore A hardness of the relief layer which a flexographic printing plate has is 50 degree or more and 90 degrees or less. When the Shore A hardness of the relief layer is 50 ° or more, even if the fine halftone dots formed by engraving are subjected to the strong printing pressure of the relief printing press, they do not collapse and can be printed normally. In addition, when the Shore A hardness of the relief layer is 90 ° or less, it is possible to prevent faint printing in a solid portion even in flexographic printing with a kiss touch.
In addition, the Shore A hardness in this specification is a numerical value obtained by indenting and deforming an indenter (called a push needle or an indenter) on a surface to be measured at 25 ° C., and measuring the deformation amount (indentation depth). This is a value measured with a durometer (spring type rubber hardness meter).

  The flexographic printing plate of the present invention is particularly suitable for printing with water-based ink by a flexographic printing machine, but printing is possible with any of water-based ink, oil-based ink and UV ink by a relief printing press. In addition, printing with UV ink by a flexographic printing machine is also possible. The flexographic printing plate of the present invention has excellent rinsing properties, no engraving residue remains, and the obtained relief layer is excellent in elasticity, so that it has excellent water-based ink transfer properties and printing durability, and a relief layer over a long period of time. Thus, printing can be carried out without concern for plastic deformation or deterioration of printing durability.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these examples. In the following description, “part” means “part by mass” unless otherwise specified, and “%” means “% by mass”. Moreover, the unit of each numerical value in Table 1 mentioned later is a mass part.
In addition, the number average molecular weight (Mn) and the weight average molecular weight (Mw) of the polymer in an Example have shown the value measured by GPC method unless there is particular notice.

Details of the components used in each example and comparative example are as follows.
<Binder polymer>
BR150L: polybutadiene (Mooney viscosity (ML _{1 + 4} , 100 ° C.): 43, Mw: 467,000, Mn: 243,000, Tg: about −103 ° C., tensile permanent strain: 63%, manufactured by Ube Industries, Ltd. UBEPOL BR150L)
IR2200L: polyisoprene (Mooney viscosity (ML _{1 + 4} , 100 ° C.): 70, Mw: 1.35 million, Mn: 472,000, Tg: about −60 ° C., tensile set: 53%, Nippon Zeon Co., Ltd. (NIPOL IR2200L)
D1102: Styrene-butadiene-styrene block copolymer (SBS resin, Mw: 100,000, Tensile permanent set: 0%, Kraton D1102 manufactured by Kraton)
TR2000: SBR (styrene butadiene rubber), manufactured by JSR Corporation, Tg = −50 ° C., 100 ° C., Mw = 56,000, BUTYL 365: Butyl rubber (isobutylene-isoprene copolymer), manufactured by JSR Corporation, Mw = 260,000

<Polymerization initiator>
-PCD-40: Dicumyl peroxide (organic peroxide, Park Mill D-40 manufactured by NOF Corporation, containing 40% dicumyl peroxide, 10-hour half-life temperature: 116.4 ° C)
Irgacure 651: photopolymerization initiator, 2-phenyl-2,2-dimethoxyacetophenone (IRGACURE 651, manufactured by Ciba Geigy)

<Polymerizable compound>
HDDA: hexanediol diacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.)
<Photothermal conversion agent>
# 45L: Carbon black # 45L (Mitsubishi Chemical Corporation, particle size: 24 nm, specific surface area: 125 m ² / g, DBP oil absorption: 45 ml / 100 g)

<Synthesis of Polymer Particle (MG-1) Containing Metathesis Catalyst>
In a suspension of ethyl acetate (470.7 parts) with 355.6 parts (1.60 molar equivalents) of isophorone diisocyanate (IPDI) and 169.6 parts (0.40 molar equivalents) of a polyphenol compound (the following structure). A solution prepared by dissolving 0.471 parts of stannous octylate (Stanocto, Yoshitomi Pharmaceutical Co., Ltd.) in 10 parts of ethyl acetate was added dropwise over 1 hour with stirring. After dropping, stirring was continued for 2 hours, and then stirring was performed at 50 ° C. for 3 hours. In this way, a solution (solution A) of the polyvalent isocyanate adduct was obtained.

Grubbs catalyst (first generation) as an oil phase component (Cat-1, manufactured by Aldrich, the following structure, Cy represents a cyclohexyl group) A solution prepared by dissolving 0.011 part in 10 parts of methyl ethyl ketone, the solution prepared above 20 parts of A, 1.0 part of an adduct of trimethylolpropane and xylene diisocyanate (manufactured by Mitsui Chemicals, Takenate D-110N), trimethylolpropane, xylene diisocyanate and polyethylene glycol monomethyl ether 5 parts of an adduct (manufactured by Mitsui Chemicals, Takenate D-116N) were mixed and stirred at room temperature (25 ° C., the same applies hereinafter) for 30 minutes to obtain Solution B.
An aqueous solution C composed of 15 parts of a 4% by weight aqueous solution of alkylbenzene sulfonate (Takemoto Yushi Co., Ltd., Pionein A-41C) and 21 parts of distilled water was prepared.

Solution B and aqueous solution C were mixed and emulsified for 12 minutes at 12,000 rpm using a homogenizer. The obtained emulsion was added to 13 parts of distilled water, stirred at room temperature for 30 minutes, and then stirred at 40 ° C. for 4 hours. The polymer particle liquid thus obtained was diluted with distilled water to a solid content concentration of 15% by mass, and then diluted with U-CAT SA102 (DBU (1,8-diazabicyclo [5.4.0]. ] -7-Undecene) -octylate (manufactured by San Apro Co., Ltd.) and containing the metathesis catalyst by allowing it to stand for 48 hours in a thermostatic chamber at 45 ° C. with the container plugged. A polymer particle (MG-1) dispersion was obtained. The average particle diameter of the polymer particles MG-1 measured by the light scattering method was 0.20 μm.
The MG-1 dispersion was poured into a petri dish, allowed to stand at room temperature for 15 hours, and then dried at 50 ° C. under reduced pressure for 8 hours to obtain powdery MG-1.

<Synthesis of polymer particle (MG-2) not containing metathesis catalyst>
A polymer particle (MG-2) containing no metathesis catalyst was produced by the same method as the synthesis of MG-1 except that the Grubbs catalyst was not added. The average particle diameter of the polymer particles MG-2 measured by the light scattering method was 0.21 μm.

<Synthesis of PU-1>
In a three-necked flask equipped with a condenser, a mixture of Poly bd R-45HT (polybutadiene diol, manufactured by Idemitsu Kosan Co., Ltd.) and isophorone diisocyanate (manufactured by Wako Pure Chemical Industries, Ltd.) (NCO / OH = 1.05). The mixture is adjusted so that the molar ratio is adjusted) and stirred at room temperature (25 ° C., the same applies hereinafter) under a nitrogen atmosphere. 0.1 part) was added and further stirred at room temperature for 30 minutes. Thereafter, the reaction solution was heated and stirred at 80 ° C. for 5 hours, 1 part of 1-methoxy-2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further heated and stirred for 1 hour. By this operation, polyurethane PU-1 having a polybutadiene chain was obtained as a highly viscous liquid. The polymer was identified by GPC (Mw = 56,000), NMR, and IR.

<Synthesis of PU-2>
A high-viscosity liquid is obtained in the same manner as in the synthesis of PU-1, except that 1 part of 1-methoxy-2-propanol is changed to 1 part of 2-hydroxyethyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.). As a product, polyurethane acrylate PU-2 having a polybutadiene chain was obtained. The polymer was identified by GPC (Mw = 56,000), NMR, and IR.

(Examples 1-8 and Comparative Examples 1-5)
<Preparation of laser engraving type flexographic printing plate precursor>
Based on the materials and compositions described in Table 1 and Table 2 described later, each material excluding the polymerization initiator was kneaded (60 ° C., 20 minutes) with Labo Plast Mill (manufactured by Toyo Seiki Seisakusho). Thereafter, a polymerization initiator was added and further kneaded (80 ° C. for 5 minutes) to obtain a resin composition for laser engraving. The obtained resin composition is molded into a sheet having a thickness of 1 mm by a rubber extruder, and this is put into a heating furnace and crosslinked by heating at 140 ° C. for 80 minutes, so that a laser engraving-type flexographic printing plate precursor Got.

<Preparation of flexographic printing plate>
The crosslinked resin composition layer (crosslinked relief forming layer) was engraved with the following two types of lasers.
As a carbon dioxide laser engraving machine, engraving by laser irradiation was performed using a high-quality CO ₂ laser marker ML-9100 series (manufactured by Keyence Corporation). Using a carbon dioxide laser engraving machine, a 1 cm square solid part was raster engraved under the conditions of output: 12 W, head speed: 200 mm / second, pitch setting: 2,400 DPI.
As a semiconductor laser engraving machine, a laser recording apparatus equipped with a fiber-coupled semiconductor laser (FC-LD) SDL-6390 (JDSU, wavelength 915 nm) having a maximum output of 8.0 W was used. A 1 cm square solid part was raster engraved with a semiconductor laser engraving machine under conditions of laser output: 7.5 W, head speed: 409 mm / second, pitch setting: 2,400 DPI.
The engraving machine used is shown in Table 2. “FC-LD” means that a semiconductor laser engraving machine was used, and “CO ₂ ” means that a carbon dioxide laser engraving machine was used.

Example 9
Based on the materials and compositions described in Table 1 and Table 2 described later, each material excluding the polymerization initiator was kneaded (60 ° C., 20 minutes) with Labo Plast Mill (manufactured by Toyo Seiki Seisakusho). Thereafter, a polymerization initiator was added and further kneaded (80 ° C. for 5 minutes) to obtain a resin composition for laser engraving. The obtained resin composition is molded into a sheet having a thickness of 1 mm with a rubber extruder, and then subjected to ultraviolet exposure while being heated at 100 ° C. for 80 minutes with an ultraviolet (UV) exposure machine installed on a heating plate. To obtain a laser engraving-type flexographic printing plate precursor.
The obtained laser engraving type flexographic printing plate precursor was laser engraved in the same manner as in Example 1 to obtain a flexographic printing plate.

-Evaluation of laser engraving-type flexographic printing plate precursors and flexographic printing plates-
The performance evaluation of the laser engraving-type flexographic printing plate precursor or the flexographic printing plate obtained in the examples and comparative examples was performed according to the following items. The evaluation results are also shown in Table 2.

<Kneading stability evaluation>
Using the obtained resin composition, the torque change when kneaded at 30 ° C., specifically, the ratio of the torque after 1 minute and 10 minutes after the start of kneading was used as an index for evaluation.
A: (torque after 10 minutes / torque after 1 minute) = 0.9 to 1.0
B: (torque after 10 minutes / torque after 1 minute) <0.9
When the decomposition of the binder polymer by the metathesis catalyst occurs, the viscosity of the kneaded product decreases as the weight average molecular weight of the binder polymer decreases. As a result, the torque during kneading decreases with time, so a decrease in torque ratio is observed and the kneading stability is poor. If the binder polymer does not decompose during kneading, the torque ratio becomes a value close to 1, and a flexographic printing plate and a flexographic printing plate having excellent kneading stability, more stable performance, and less yield can be obtained.

<Evaluation of engraving sensitivity (sculpture depth)>
The “engraved depth” of the relief layer obtained by laser engraving the crosslinked relief forming layer of the flexographic printing plate precursor was measured as follows. Here, “sculpture depth” refers to the difference between the engraved position (height) and the unengraved position (height) when the cross section of the relief layer is observed. The “engraving depth” in this example was measured by observing the cross section of the relief layer with an ultra-deep color 3D shape measuring microscope VK9510 (manufactured by Keyence Corporation). A large engraving depth means high engraving sensitivity.

<Rinse evaluation>
The laser engraved plate was immersed in water. Then, the presence or absence of debris on the surface of the relief layer was confirmed with an optical microscope. A case where no residue was left was A, a little residue was left, but B was a level where there was no practical problem, and C was a case where the residue was not sufficiently removed.

<Print durability>
The obtained flexographic printing plate was set on a printing machine (ITM-4 type, manufactured by Iyo Machinery Co., Ltd.). As the ink, solvent ink (XS-716 507 primary color indigo (manufactured by DIC Graphics Co., Ltd.)) was used. Printing was continued using full-color foam M70 (manufactured by Nippon Paper Industries Co., Ltd., thickness: 100 μm) as printing paper, and highlights of 1 to 10% were confirmed with printed matter. Printing was performed when a halftone dot that was not printed occurred, and the length (km) of the paper printed before the printing was used as an index. The larger the value, the better the printing durability.

  Cat-1 in Comparative Example 3 described in Table 2 represents the above-described Grubbs catalyst (first generation) (manufactured by Aldrich).

Claims (16)

(Component A) polymer particles containing a metathesis catalyst, and
(Component B) A polymer having an ethylenically unsaturated group, a resin composition for laser engraving.   The resin composition for laser engraving according to claim 1, wherein the component B has a weight average molecular weight of 500,000 or more.   The resin composition for laser engraving according to claim 1 or 2, further comprising (Component C) a crosslinking agent.   The resin composition for laser engraving according to claim 3, wherein Component C is a peroxide.   The resin composition for laser engraving according to any one of claims 1 to 4, wherein Component B is a plastomer at 20 ° C.   (Component D) The resin composition for laser engraving according to any one of claims 1 to 5, further comprising a photothermal conversion agent.   The resin composition for laser engraving according to claim 6, wherein Component D is carbon black.   A laser engraving-type flexographic printing plate precursor having a relief forming layer comprising the resin composition for laser engraving according to claim 1.   A laser engraving-type flexographic printing plate precursor having a crosslinked relief-forming layer obtained by crosslinking the relief-forming layer made of the resin composition for laser engraving according to claim 1. A layer forming step of forming a relief forming layer comprising the resin composition for laser engraving according to any one of claims 1 to 7, and
A method for producing a laser engraving type flexographic printing plate precursor, comprising a crosslinking step of crosslinking the relief forming layer with light and / or heat to obtain a flexographic printing plate precursor having a crosslinked relief forming layer.   The production of the laser engraving-type flexographic printing plate precursor according to claim 10, wherein the layer forming step includes a step of kneading the resin composition for laser engraving and a step of forming the kneaded product into a sheet shape. Method.   The method for producing a laser engraving-type flexographic printing plate precursor according to claim 11, wherein the step of forming into a sheet is a step of forming into a sheet by hot pressing or extrusion.   The method for producing a laser engraving-type flexographic printing plate precursor according to any one of claims 10 to 12, wherein in the crosslinking step, the relief forming layer is crosslinked by heat. Preparing a laser engraving type flexographic printing plate precursor according to claim 9 or a laser engraving type flexographic printing plate precursor produced by the production method according to any one of claims 10 to 13; and
A method for making a flexographic printing plate, comprising: engraving a laser beam on the flexographic printing plate precursor for laser engraving to form a relief layer.   The method for making a flexographic printing plate according to claim 14, further comprising a rinsing step of rinsing the relief layer surface with an aqueous rinsing liquid after the engraving step.   A flexographic printing plate obtained by the plate making method of a flexographic printing plate according to claim 14 or 15.