Flexographic printing plate precursor and method for manufacturing flexographic printing plate

Abstract

The present invention addresses the problem of providing a flexographic printing plate original plate that suppresses the occurrence of wrinkling in an infrared ablation layer and demonstrates good microcell reproducibility when made into a flexographic printing plate, as well as providing a method for manufacturing a flexographic printing plate using said flexographic printing plate original plate. This flexographic printing plate original plate has a support body, a photosensitive layer, an intermediate layer, and an infrared ablation layer, in this order. The intermediate layer includes a rubber component and a resin component, and the resin component includes at least one of an acrylic resin and a methacrylic resin.

Description

[Technical Field]

[0001] The present invention relates to a flexographic printing plate precursor and a method for producing a flexographic printing plate using the same. [Background technology]

[0002] A flexographic printing plate master generally comprises a photosensitive resin layer (photosensitive layer) made of a photosensitive resin composition on a support made of polyester film, etc. A flexographic printing plate is made by exposing the surface of the photosensitive resin layer of this master to light with a predetermined image and then removing the resin in the unexposed areas.

[0003] In a so-called analog type flexographic printing plate precursor, a negative film on which a predetermined image has already been formed is placed on a photosensitive layer, and the predetermined image is exposed onto the surface of the photosensitive layer through this negative film. In contrast, a flexographic printing plate precursor using the LAM (Laser ablation mask) method has an infrared ablation layer pre-formed on a photosensitive layer, and a desired negative pattern is created by directly drawing digitized negative image information on the infrared ablation layer using an infrared laser, and then a predetermined image is exposed onto the surface of the photosensitive layer through this negative pattern.

[0004] As an example of such a LAM type flexographic printing plate precursor, Patent Document 1 describes a flexographic printing plate precursor in which a support, a photosensitive resin layer, and an infrared ablation layer containing a binder polymer and an infrared absorbing substance are laminated. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-137515 Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors attempted to form a fine uneven pattern (hereinafter also abbreviated as "microcells") on the surface of the image area of ​​a known flexographic printing plate precursor described in Patent Document 1 and the like, in order to improve ink transferability when the flexographic printing plate is made into a flexographic printing plate. Specifically, when an oxygen-blocking layer (intermediate layer) as described in International Publication No. 2017 / 056763 was provided on top of the photosensitive layer, it was found that the reproducibility of microcells improved when the plate was made into a flexographic printing plate, but it was also found that wrinkles occurred in the infrared ablation layer.

[0007] Therefore, an object of the present invention is to provide a flexographic printing plate precursor that suppresses the occurrence of wrinkles in the infrared ablation layer and provides good reproducibility of microcells when made into a flexographic printing plate, and a method for manufacturing a flexographic printing plate using the same. [Means for solving the problem]

[0008] As a result of extensive research to achieve the above object, the present inventors have found that a flexographic printing plate precursor having, in this order, a support, a photosensitive layer, an intermediate layer containing a rubber component and a predetermined resin component, and an infrared ablation layer suppresses the occurrence of wrinkles in the infrared ablation layer and provides good reproducibility of microcells when made into a flexographic printing plate, thereby completing the present invention. That is, the present inventors have found that the above object can be achieved by the following configuration.

[0009] [1] A flexographic printing plate precursor having a support, a photosensitive layer, an intermediate layer, and an infrared ablation layer in this order, the intermediate layer contains a rubber component and a resin component, A flexographic printing plate precursor, wherein the resin component contains at least one of an acrylic resin and a methacrylic resin. [2] The flexographic printing plate precursor according to [1], wherein the intermediate layer further contains at least one of an oxygen scavenger and inorganic layered particles. [3] The flexographic printing plate precursor according to [2], wherein the oxygen scavenger is at least one compound selected from the group consisting of phosphite compounds, phosphine compounds, and thioether compounds. [4] The flexographic printing plate precursor according to [2], wherein the inorganic layered particles are at least one selected from the group consisting of mica, talc, taeniolite, montmorillonite, saponite, hectorite, and zirconium phosphate. [5] The flexographic printing plate precursor according to any one of [1] to [4], wherein the resin component has a glass transition temperature of 48 to 80°C. [6] The flexographic printing plate precursor according to any one of [1] to [5], wherein the mass ratio of the rubber component to the resin component is within the range of 1 / 3 to 3 / 1. [7] A method for producing a flexographic printing plate having non-image areas and image areas, comprising: a mask forming step of forming an image on an infrared ablation layer of the flexographic printing plate precursor according to any one of [1] to [6] to form a mask; an exposure step of exposing a photosensitive layer of the flexographic printing plate precursor to light in an imagewise manner through a mask after the mask formation step; A method for producing a flexographic printing plate, comprising a development step, after the exposure step, of developing with a developer to form non-image areas and image areas. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a flexographic printing plate precursor that suppresses the occurrence of wrinkles in the infrared ablation layer and provides good reproducibility of microcells when made into a flexographic printing plate, and a method for manufacturing a flexographic printing plate using the same. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a flexographic printing plate precursor of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below. The following description of the components may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In addition, in this specification, each component may be a single substance corresponding to the component, or two or more substances may be used in combination. Here, when two or more substances are used in combination for each component, the content of that component refers to the total content of the substances used in combination, unless otherwise specified.

[0013] [Flexographic printing plate precursor] The flexographic printing plate precursor of the present invention is a flexographic printing plate precursor having a support, a photosensitive layer, an intermediate layer, and an infrared ablation layer in this order. The intermediate layer contains a rubber component and a resin component. The resin component contains at least one of an acrylic resin and a methacrylic resin.

[0014] FIG. 1 is a schematic cross-sectional view showing an example of a flexographic printing plate precursor of the present invention. The flexographic printing plate precursor 10 shown in FIG. 1 has a support 1, a photosensitive layer 2, an intermediate layer 3, and an infrared ablation layer 4 in this order. The flexographic printing plate precursor of the present invention may also have a cover sheet 5 as shown in FIG.

[0015] In the present invention, when the intermediate layer of the flexographic printing plate precursor contains a rubber component and a resin component, and contains at least one of an acrylic resin and a methacrylic resin as the resin component, the occurrence of wrinkles in the infrared ablation layer is suppressed, and the reproducibility of microcells is improved when the flexographic printing plate precursor is made. Although the details of this are not clear, the present inventors speculate as follows. First, the reason why the reproducibility of microcells is good when the plate is made into a flexographic printing plate is thought to be because the provision of the intermediate layer described above suppresses polymerization inhibition by oxygen compared to when no intermediate layer is provided. This can also be inferred from the fact that the reproducibility of microcells is improved when an oxygen scavenger or the like is blended into the intermediate layer. On the other hand, wrinkles in the infrared ablation layer are thought to occur for the following reasons. In other words, the oxygen-blocking layer described in the above-mentioned International Publication No. 2017 / 056763 and the like has weak adhesion to the adjacent photosensitive layer and infrared ablation layer, so when stress is applied to the flexographic printing plate precursor, wrinkles occur in the oxygen-blocking layer, and as a result, wrinkles also occur in the infrared ablation layer. Therefore, in the present invention, since the above-mentioned intermediate layer contains a rubber component and a specified resin component, adhesion to the adjacent photosensitive layer and infrared ablation layer is improved, and the intermediate layer does not undergo plastic deformation when stress is applied to the flexographic printing plate precursor, making it less likely for wrinkles to occur in the intermediate layer, which is thought to have suppressed the occurrence of wrinkles in the infrared ablation layer. The layer structure of the flexographic printing plate precursor of the present invention will be described in detail below.

[0016] [Support] The material used for the support of the flexographic printing plate precursor of the present invention is not particularly limited, but materials with high dimensional stability are preferably used, and examples thereof include metals such as steel, stainless steel, and aluminum; polyesters (e.g., PET (polyethylene terephthalate), PBT (polybutylene terephthalate), and PEN (polyethylene naphthalate)), PI (polyimide), polyamide, LCP (liquid crystal polymer), and PAN (polyacrylonitrile); plastic resins such as polyvinyl chloride; synthetic rubbers such as styrene-butadiene rubber; plastic resins (e.g., epoxy resins and phenolic resins) reinforced with glass fibers; cloth, paper, and the like. From the viewpoints of dimensional stability and availability, the support is preferably a polymer film or cloth, more preferably a polymer film. The form of the support is determined by whether the polymer layer is in the form of a sheet or a sleeve.

[0017] As the cloth, plain weave or twill woven fabrics, various knitted fabrics, and nonwoven fabrics can be used, made from natural fibers such as cotton, linen, silk, and wool, and synthetic fibers such as acetate, vinylon, vinylidene, polyvinyl chloride, acrylic, polypropylene, polyethylene, polyurethane, fluorine-based filaments, polychlor, rayon, nylon, polyamide, and polyester. Examples of polymer films include films formed from various polymers such as polyester (e.g., PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PEN (polyethylene naphthalate)), PI (polyimide), polyamide, LCP (liquid crystal polymer), PAN (polyacrylonitrile); plastic resins such as polyvinyl chloride; synthetic rubbers such as styrene-butadiene rubber; and plastic resins reinforced with glass fibers (epoxy resins, phenolic resins, etc.). Of these, polyester films are preferred from the standpoint of dimensional stability, etc. Examples of the polyester film include a PET film, a PBT film, and a PEN film, but from the viewpoint of dimensional stability and the like, a PET (polyethylene terephthalate) film is preferred.

[0018] The thickness of the support is not particularly limited, but from the viewpoint of dimensional stability and handleability, it is preferably 5 to 3000 μm, more preferably 50 to 2000 μm, and even more preferably 100 to 1000 μm.

[0019] [Photosensitive layer] The photosensitive layer of the flexographic printing plate precursor of the present invention can be formed using a conventionally known photosensitive resin composition. In the present invention, the photosensitive layer preferably contains water-dispersible particles, a binder, a monomer, a photopolymerization initiator, and a polymerization inhibitor.

[0020] <Water dispersible particles> The water-dispersible particles are not particularly limited, but are preferably polymers because they further suppress the occurrence of wrinkles in the infrared ablation layer and improve the reproducibility of microcells when made into a flexographic printing plate. Hereinafter, "further suppressing the occurrence of wrinkles in the infrared ablation layer and improving the reproducibility of microcells when made into a flexographic printing plate" will also be referred to as "the effects, etc. of the present invention are better." Specific examples of the polymer include diene polymers (e.g., polybutadiene, natural rubber, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, methyl methacrylate-butadiene copolymer, polychloroprene, polyisoprene), polyurethane, vinylpyridine polymer, butyl polymer, thiokol polymer, acrylate polymer, and polymers obtained by copolymerizing these polymers with other components such as acrylic acid and methacrylic acid, and these may be used alone or in combination of two or more. The polymer is preferably a polymer obtained by polymerizing at least one monomer selected from the group consisting of isoprene, butadiene, styrene, butyl, ethylene, propylene, acrylic acid esters, and methacrylic acid esters, and is more preferably polybutadiene, because it has better resistance to aqueous inks. The polymer preferably does not have reactive functional groups (for example, (meth)acryloyloxy groups) at both ends. Note that "(meth)acryloyl" is a notation meaning acryloyl or methacryloyl.

[0021] The polymer is preferably a polymer obtained by removing water from a water-dispersed latex, for reasons of better effects of the present invention, etc. Specific examples of the water-dispersed latex include the water-dispersed latexes of the specific examples of the polymers described above.

[0022] The content of the water-dispersible particles is preferably 5 to 80% by mass, more preferably 10 to 60% by mass, and even more preferably 20 to 45% by mass, relative to the total mass of the solid content of the photosensitive layer, for reasons such as better effects of the present invention.

[0023] <Binder> The binder is not particularly limited, and examples thereof include thermoplastic polymers. The thermoplastic polymer is not particularly limited as long as it is a polymer that exhibits thermoplasticity, and specific examples thereof include polystyrene resin, polyester resin, polyamide resin, polysulfone resin, polyethersulfone resin, polyimide resin, acrylic resin, acetal resin, epoxy resin, polycarbonate resin, rubber, thermoplastic elastomer, etc. These may be used alone or in combination of two or more. Among these, rubber and thermoplastic elastomers are preferred, rubber is more preferred, and diene rubber is even more preferred, because they make it easier to form a soft and flexible film.

[0024] The rubber is preferably a non-flowable rubber, which does not have flowability, in order to ensure the elasticity of the flexographic printing plate. Specific examples include butadiene rubber (BR), nitrile rubber (NBR), acrylic rubber, epichlorohydrin rubber, urethane rubber, isoprene rubber, styrene-isoprene rubber, styrene-butadiene rubber (SBR), ethylene-propylene copolymer, chlorinated polyethylene, etc., and these may be used alone or in combination of two or more. Among these, at least one rubber selected from the group consisting of butadiene rubber (BR), styrene-butadiene rubber (SBR), and nitrile rubber (NBR) is preferred from the viewpoint of better water developability, drying properties, and image reproducibility, and butadiene rubber and styrene-butadiene rubber are more preferred from the viewpoint of water-based ink resistance.

[0025] Examples of the thermoplastic elastomer include PB (polybutadiene-based thermoplastic elastomer), polyisoprene-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, and acrylic-based thermoplastic elastomer. Specific examples include SB (polystyrene-polybutadiene), SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), SEBS (polystyrene-polyethylene / polybutylene-polystyrene), ABS (acrylonitrile butadiene-styrene copolymer), ACM (acrylic acid ester rubber), ACS (acrylonitrile-chlorinated polyethylene-styrene copolymer), acrylonitrile-styrene copolymer, syndiotactic 1,2-polybutadiene, polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate, and the like. Of these, PB, SBS, and SIS are particularly preferred because of their improved water-developability and drying properties and image reproducibility.

[0026] The content of the binder is preferably from 1 to 50% by mass, more preferably from 5 to 40% by mass, and even more preferably from 7 to 30% by mass, based on the total mass of the solid content of the photosensitive layer.

[0027] <Monomer> The monomer is not particularly limited, but it is preferable to use a monofunctional monomer and a bifunctional monomer in combination, because this will provide better effects of the present invention.

[0028] (monofunctional monomer) The monofunctional monomer is preferably a compound having one ethylenically unsaturated group, for reasons such as better effects of the present invention. Examples of the ethylenically unsaturated group include radically polymerizable groups including an acryloyl group, a methacryloyl group, a vinyl group, a styryl group, and an allyl group. Among these, an acryloyl group, a methacryloyl group, and a C(O)OCH=CH2 group are preferred, and an acryloyl group and a methacryloyl group are more preferred.

[0029] Examples of compounds having one ethylenically unsaturated group include: N-vinyl compounds such as N-vinylformamide; (meth)acrylamide compounds such as (meth)acrylamide, N-methylol (meth)acrylamide, diacetone (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, (meth)acryloylmorpholine, and (meth)acrylamide; 2-Hydroxyethyl (meth)acrylate, Butoxyethyl (meth)acrylate, Carbitol (meth)acrylate, Cyclohexyl (meth)acrylate, Tetrahydrofurfuryl (meth)acrylate, Benzyl (meth)acrylate, Tridecyl (meth)acrylate, 2-Phenoxyethyl (meth)acrylate, Glycidyl (meth)acrylate, Isobornyl (meth)acrylate, Dicyclopentenyl (meth)acrylate, Dicyclopentenyloxyethyl (meth)acrylate, Dicyclopentanyl (meth)acrylate, 2-Hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl phthalate, Methoxy-Polyethylene Glycol (meth)acrylate, 2-(meth)acryloyloxyethyl (meth)acrylate compounds such as ethyl-2-hydroxyethyl phthalate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethoxylated phenyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, nonylphenol EO adduct (meth)acrylate, phenoxy-polyethylene glycol (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalate, lactone-modified (meth)acrylate, stearyl (meth)acrylate, isoamyl (meth)acrylate, isomyristyl (meth)acrylate, isostearyl (meth)acrylate, and cyclic trimethylolpropane formal (meth)acrylate; Methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, t-butyl vinyl ether, n-octadecyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, cyclohexylmethyl vinyl ether, 4-methylcyclohexylmethyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether Monovinyl ether compounds such as ethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexylmethyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxypolyethylene glycol vinyl ether, cyclohexanedimethanol monovinyl ether, and isopropenyl ether-O-propylene carbonate; The following are examples: EO stands for ethylene oxide.

[0030] The content of the monofunctional monomer is preferably 0.1 to 30% by mass, and more preferably 1 to 10% by mass, based on the total mass of the solid content of the photosensitive layer, for reasons such as better effects of the present invention.

[0031] (Difunctional Monomer) The bifunctional monomer is preferably a compound having two ethylenically unsaturated groups, because this provides better effects of the present invention, etc. Specific examples of the ethylenically unsaturated groups are as described above.

[0032] Examples of compounds having two ethylenically unsaturated groups include: glycol di(meth)acrylate compounds such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, ethoxylated neopentyl glycol di(meth)acrylate, and propoxylated neopentyl glycol di(meth)acrylate; divinyl ether compounds such as ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, and cyclohexanedimethanol divinyl ether; Bisphenol A di(meth)acrylate compounds such as bisphenol A diglycidyl ether (meth)acrylic acid adduct, modified bisphenol A di(meth)acrylate, bisphenol A PO adduct di(meth)acrylate, and bisphenol A EO adduct di(meth)acrylate; In addition, PO represents propylene oxide and EO represents ethylene oxide.

[0033] The content of the bifunctional monomer is preferably 0.1 to 30% by mass relative to the total mass of the solid content of the photosensitive layer, because this provides better effects of the present invention.

[0034] <Photopolymerization initiator> The photosensitive layer preferably contains a photopolymerization initiator, for reasons such as the fact that the effects of the present invention are more excellent. The photopolymerization initiator is not particularly limited, and examples thereof include alkylphenones, acetophenones, benzoin ethers, benzophenones, thioxanthones, anthraquinones, benzils, and biacetyls. More specific examples include benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, methyl-o-benzoylbenzoate, and 1-hydroxycyclohexyl phenyl ketone.

[0035] From the viewpoint of sensitivity, the content of the photopolymerization initiator is preferably 0.3 to 15% by mass, and more preferably 0.5 to 10% by mass, based on the total mass of the solid content of the photosensitive layer.

[0036] <Polymerization inhibitor> The photosensitive layer preferably contains a polymerization inhibitor (stabilizer) for the reason that the effects of the present invention are more excellent. Examples of the polymerization inhibitor include phenols, hydroquinones, and catechols.

[0037] The content of the polymerization inhibitor is preferably 0.01 to 5 mass %, more preferably 0.01 to 0.5 mass %, relative to the total mass of the solid content of the photosensitive layer, for the reason that the development residue dispersibility of the flexographic printing plate precursor after storage over time is better.

[0038] <Telechelic polymer> The photosensitive layer preferably contains a telechelic polymer because the effects of the present invention are more excellent. In this specification, the term "telechelic polymer" refers to a polymer having reactive functional groups at both ends.

[0039] (main chain) The polymer constituting the main chain of the telechelic polymer is not particularly limited, but examples thereof include thermoplastic polymers. The thermoplastic polymer is not particularly limited as long as it is a polymer that exhibits thermoplasticity, and specific examples thereof include polystyrene resin, polyester resin, polyamide resin, polysulfone resin, polyethersulfone resin, polyimide resin, acrylic resin, acetal resin, epoxy resin, polycarbonate resin, rubber, and thermoplastic elastomer. Among these, rubber and thermoplastic elastomers are preferred, rubber is more preferred, and diene rubber is even more preferred, because a softer and more flexible film can be more easily formed.

[0040] Specific examples of the rubber include butadiene rubber (BR), nitrile rubber (NBR), acrylic rubber, epichlorohydrin rubber, urethane rubber, isoprene rubber, styrene-isoprene rubber, styrene-butadiene rubber (SBR), ethylene-propylene copolymer, chlorinated polyethylene, etc., and these may be used alone or in combination of two or more. Among these, at least one rubber selected from the group consisting of butadiene rubber (BR), styrene-butadiene rubber (SBR), and nitrile rubber (NBR) is preferred, with butadiene rubber and styrene-butadiene rubber being more preferred, for the reason that water developability is improved and from the viewpoint of drying properties and image reproducibility.

[0041] Examples of the thermoplastic elastomer include PB (polybutadiene-based thermoplastic elastomer), polyisoprene-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, and acrylic-based thermoplastic elastomer. Specific examples include SB (polystyrene-polybutadiene), SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), SEBS (polystyrene-polyethylene / polybutylene-polystyrene), ABS (acrylonitrile butadiene-styrene copolymer), ACM (acrylic acid ester rubber), ACS (acrylonitrile-chlorinated polyethylene-styrene copolymer), acrylonitrile-styrene copolymer, syndiotactic 1,2-polybutadiene, polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate, and the like. Of these, PB, SBS, and SIS are particularly preferred because of their improved water-developability and drying properties and image reproducibility.

[0042] (end) Telechelic polymers have reactive functional groups at both ends. The reactive functional group is not particularly limited, but is preferably an ethylenically unsaturated group because it provides better effects of the present invention. The ethylenically unsaturated group is preferably a vinyl group (CH2=CH-), an allyl group (CH2=CH-CH2-), a (meth)acryloyl group, or a (meth)acryloyl group, and more preferably a (meth)acryloyloxy group, because this provides better effects of the present invention.

[0043] The telechelic polymer may have reactive functional groups at both ends of the polymer constituting the main chain via divalent linking groups. The divalent linking group is not particularly limited, and examples thereof include linear, branched, or cyclic divalent aliphatic hydrocarbon groups (e.g., alkylene groups such as methylene, ethylene, and propylene), divalent aromatic hydrocarbon groups (e.g., phenylene), -O-, -S-, -SO2-, -NRL-, -CO-, -NH-, -COO-, -CONRL-, -O-CO-O-, -SO3-, -NHCOO-, -SONRL-, -NH-CO-NH-, and groups combining two or more of these (e.g., alkyleneoxy, alkyleneoxycarbonyl, and alkylenecarbonyloxy groups). Here, RL represents a hydrogen atom or an alkyl group (preferably having 1 to 10 carbon atoms).

[0044] (molecular weight) The weight average molecular weight (Mw) of the telechelic polymer is preferably 6,000 or more, more preferably 7,000 or more, even more preferably 8,000 or more, and particularly preferably 9,000 or more, because this will result in better effects of the present invention. There is no particular upper limit to the Mw of the telechelic polymer, but because this will result in better effects of the present invention, it is preferably 500,000 or less, and more preferably 100,000 or less. Here, the weight-average molecular weight is measured by gel permeation chromatography (GPC) and calculated using standard polystyrene. Specifically, for example, the GPC is performed using an HLC-8220GPC (manufactured by Tosoh Corporation), three columns (TSKgel Super HZM-H, TSKgel Super HZ4000, and TSKgel Super HZ2000, manufactured by Tosoh Corporation, 4.6 mm ID x 15 cm) and THF (tetrahydrofuran) as the eluent. The conditions are a sample concentration of 0.35% by mass, a flow rate of 0.35 mL / min, a sample injection volume of 10 μL, a measurement temperature of 40°C, and an IR detector. In addition, the calibration curve is prepared from eight samples of "Standard Sample TSK Standard, Polystyrene" manufactured by Tosoh Corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene".

[0045] (HSP value) The HSP (Hansen Solubility Parameter) value of the telechelic polymer is not particularly limited, but is preferably 8 to 12, more preferably 8.5 to 11, and even more preferably 8.5 to 10.5, for reasons such as better effects of the present invention.

[0046] (Content) The content of the telechelic polymer is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, even more preferably 7 to 30% by mass, and particularly preferably 10 to 20% by mass, relative to the total mass of the solid content of the photosensitive layer, for reasons such as better effects of the present invention.

[0047] <Plasticizer> The photosensitive layer preferably contains a plasticizer to improve flexibility.

[0048] Specific examples of the plasticizer include liquid rubber, oil, polyester, and phosphoric acid compounds. Specific examples of liquid rubber include liquid polybutadiene, liquid polyisoprene, and those modified with maleic acid or epoxy groups. Specific examples of oils include paraffin, naphthene, and aromatics. Specific examples of polyesters include adipic acid polyesters. Specific examples of phosphoric acid compounds include phosphate esters.

[0049] The content of the plasticizer is preferably 0.1 to 40% by mass, and more preferably 5 to 30% by mass, based on the total mass of the solid content of the photosensitive layer, for the reason that flexibility is further improved.

[0050] <Surfactant> The photosensitive layer preferably contains a surfactant from the viewpoint of further improving water developability. Examples of surfactants include cationic surfactants, anionic surfactants, and nonionic surfactants. Among these, anionic surfactants are preferred because they provide superior effects of the present invention.

[0051] Specific examples of the anionic surfactant include: aliphatic carboxylates such as sodium laurate and sodium oleate; higher alcohol sulfates such as sodium lauryl sulfate, sodium cetyl sulfate, and sodium oleyl sulfate; Polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate; Polyoxyethylene alkyl allyl ether sulfates such as sodium polyoxyethylene octylphenyl ether sulfate and sodium polyoxyethylene nonylphenyl ether sulfate; alkyl sulfonates such as alkyl diphenyl ether disulfonates, sodium dodecyl sulfonate, and sodium dialkyl sulfosuccinate; alkyl aryl sulfonates such as alkyl disulfonates, sodium dodecylbenzenesulfonate, sodium dibutylnaphthalenesulfonate, and sodium triisopropylnaphthalenesulfonate; higher alcohol phosphate ester salts such as disodium lauryl phosphate monoester and sodium lauryl phosphate diester; Polyoxyethylene alkyl ether phosphate ester salts such as polyoxyethylene lauryl ether phosphate monoester disodium and polyoxyethylene lauryl ether phosphate diester sodium; These may be used alone or in combination of two or more.

[0052] Among these, sulfonic acid surfactants such as alkyl sulfonates and alkyl aryl sulfonates are preferred because they provide better water developability.

[0053] From the viewpoint of developability and drying property after development, the content of the surfactant is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, based on the total mass of the solid content of the photosensitive layer.

[0054] <Other additives> To improve various properties, additives such as ultraviolet absorbers, dyes, pigments, antifoaming agents, and fragrances may be added to the photosensitive layer as appropriate, provided that the effects of the present invention are not impaired.

[0055] <Method for producing photosensitive layer> The method for producing the photosensitive layer is not particularly limited, but examples thereof include a method in which a resin composition containing the above-mentioned components is prepared and then coated on the above-mentioned support.

[0056] The thickness of the photosensitive layer is preferably 0.01 to 10 mm, and more preferably 0.2 to 6 mm.

[0057] [Middle class] As described above, the intermediate layer of the flexographic printing plate precursor of the present invention is a layer containing a rubber component and a resin component, and the resin component contains at least one of an acrylic resin and a methacrylic resin.

[0058] <Rubber component> The rubber component contained in the intermediate layer is not particularly limited as long as it is a rubber that does not impair adhesion to the photosensitive layer described above and the infrared ablation layer described below. Specific examples of rubber include butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), acrylic rubber, epichlorohydrin rubber, urethane rubber, isoprene rubber (IR), styrene isoprene rubber (SIR), styrene butadiene rubber (SBR), ethylene-propylene copolymer, and chlorinated polyethylene. These may be used alone or in combination of two or more. Among these, butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), or styrene butadiene rubber (SBR) is preferred, and acrylonitrile butadiene rubber (NBR) is more preferred, because they provide good adhesion to the adjacent photosensitive layer and infrared ablation layer.

[0059] The content of the rubber component is preferably 15 to 85 mass% of the total mass of the rubber component and the resin component, more preferably more than 20 mass% and less than 80 mass%, further preferably 25 to 75 mass%, and particularly preferably 30 to 70 mass%.

[0060] In the present invention, in order to further suppress the occurrence of wrinkles in the infrared ablation layer, the mass ratio of the rubber component to the resin component (described later) (rubber component / resin component) is preferably in the range of 1 / 3 to 3 / 1. In particular, the mass ratio of the rubber component to the acrylic resin and methacrylic resin among the resin components (rubber component / resin component) is preferably in the range of 1 / 3 to 3 / 1.

[0061] <Resin component> The resin component contained in the intermediate layer is not particularly limited as long as it contains at least one of an acrylic resin and a methacrylic resin (hereinafter abbreviated as "(meth)acrylic resin"). Here, the (meth)acrylic resin is not particularly limited as long as it is a polymer or copolymer of one or more monomers selected from acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters.

[0062] The resin component contained in the intermediate layer may contain a resin other than the (meth)acrylic resin. Examples of resins other than (meth)acrylic resins include polystyrene resins, polyester resins, polyamide resins, polysulfone resins, polyethersulfone resins, polyimide resins, acrylic resins, acetal resins, epoxy resins, and polycarbonate resins.

[0063] The content of the resin component is preferably 15 to 85 mass% of the total mass of the rubber component and the resin component, more preferably more than 20 mass% and less than 80 mass%, further preferably 25 to 75 mass%, and particularly preferably 30 to 70 mass%.

[0064] In the present invention, the glass transition temperature (Tg) of the resin component is preferably 48 to 80° C., more preferably 60 to 70° C., because this further suppresses the occurrence of wrinkles in the infrared ablation layer. In particular, the glass transition temperature of the (meth)acrylic resin among the resin components is preferably 48 to 80° C., more preferably 60 to 70° C. The glass transition temperature is measured using a differential scanning calorimeter (manufactured by Seiko Instruments Inc., product name "DSC-6200") in accordance with JIS K 7121 (1987) (Method for measuring glass transition temperature of plastics).

[0065] In the present invention, it is preferable that the intermediate layer further contains at least one of an oxygen scavenger and inorganic layered particles, because this improves the reproducibility of microcells when the flexographic printing plate is made, and improves the ink transferability in solid areas (particularly filled areas of 1 mm square or more) and improves the solid density.

[0066] <Oxygen scavenger> Suitable examples of the oxygen scavenger include at least one compound selected from the group consisting of phosphite compounds, phosphine compounds, and thioether compounds. Specific examples of the phosphite compound include triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, tris(nonylphenyl) phosphite, tris(dinonylphenyl) phosphite, tris(2,4-di-t-butylphenyl) phosphite, 10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 6-[3- Examples of such compounds include monophosphite compounds such as (3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenz[d,f][1.3.2]dioxaphosphepine and tridecyl phosphite; and diphosphite compounds such as 4,4'-butylidene-bis(3-methyl-6-t-butylphenyl-di-tridecyl phosphite) and 4,4'-isopropylidene-bis(phenyl-di-alkyl(C12-C15) phosphite). Specific examples of the phosphine compound include triphenylphosphine and tris(2,6-dimethoxyphenyl)phosphine. Specific examples of the thioether compound include 3,6-dithia-1,8-octanediol and 2,2'-thiodiethanol.

[0067] When the intermediate layer contains an oxygen scavenger, the content of the oxygen scavenger is preferably 0.05 to 5 mass %, more preferably 0.1 to 2 mass %, based on the total mass of the rubber component and the resin component.

[0068] <Inorganic layered particles> Suitable examples of inorganic layered particles include at least one selected from the group consisting of mica, talc, taeniolite, montmorillonite, saponite, hectorite, and zirconium phosphate. Of these, mica is preferred, and fluorine-based swellable mica, which is a synthetic inorganic layered compound, is particularly useful.

[0069] From the viewpoint of diffusion control, the shape of the inorganic layered particles is such that the thinner the thickness, the better, and the larger the planar size, the better, as long as it does not impair the smoothness of the coated surface or the transmittance of actinic rays. Therefore, the aspect ratio of the inorganic layered particles is preferably 20 or more, more preferably 100 or more, and even more preferably 200 or more. The aspect ratio is the ratio of the major axis to the thickness of the particle, and can be measured, for example, from a projection of the particle in a micrograph. The larger the aspect ratio, the greater the effect obtained.

[0070] The particle size of the inorganic layered particles is preferably 0.3 to 20 μm, more preferably 0.5 to 10 μm, and even more preferably 1 to 5 μm, in terms of average major axis. The average thickness of the inorganic layered particles is preferably 0.1 μm or less, more preferably 0.05 μm or less, and even more preferably 0.01 μm or less. For example, the size of swellable synthetic mica, a representative compound among inorganic layered particles, is about 1 to 50 nm in thickness and 1 to 20 μm in face size.

[0071] When the intermediate layer contains inorganic layered particles, the content of the inorganic layered particles is preferably 10 to 80 mass %, more preferably 30 to 60 mass %, based on the total mass of the rubber component and the resin component.

[0072] <Method for producing intermediate layer> The method for producing the intermediate layer is not particularly limited, but examples thereof include a method in which a composition containing the above-mentioned components is prepared and then coated on the above-mentioned photosensitive layer.

[0073] The thickness of the intermediate layer is preferably 0.1 to 6 μm, and more preferably 0.2 to 3 μm.

[0074] [Infrared ablation layer] The infrared ablation layer of the flexographic printing plate precursor of the present invention is a mask that covers the surface of the intermediate layer. The infrared ablation layer is a portion that can be removed by an infrared laser, and the portion that is not removed blocks (absorbs) ultraviolet light, masking the intermediate layer and photosensitive layer underneath so that the ultraviolet light is not irradiated onto them. Such an infrared ablation layer can be formed using a resin composition containing a binder polymer and an infrared absorbing substance.

[0075] <Binder polymer> Examples of the binder polymer contained in the resin composition include polymer components similar to the rubber component and resin component contained in the intermediate layer described above. Of these, the polymer component corresponding to the rubber component is preferably butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), or styrene butadiene rubber (SBR), and more preferably acrylonitrile butadiene rubber (NBR). The polymer component corresponding to the resin component is preferably a (meth)acrylic resin.

[0076] <Infrared absorbing material> The infrared absorbing substance contained in the resin composition is not particularly limited as long as it is a substance that can absorb infrared rays and convert them into heat. Specific examples of infrared absorbing substances include black pigments (e.g., carbon black, aniline black, cyanine black, etc.), green pigments (e.g., phthalocyanine, naphthalocyanine, etc.), rhodamine dyes, naphthoquinone dyes, polymethine dyes, diimonium salts, azoimonium dyes, chalcogen dyes, carbon graphite, iron powder, diamine metal complexes, dithiol metal complexes, phenolthiol metal complexes, mercaptophenol metal complexes, aryl aluminum metal salts, inorganic compounds containing crystal water, copper sulfate, metal oxides (e.g., cobalt oxide, tungsten oxide, etc.), and metal powders (e.g., bismuth, tin, tellurium, aluminum, etc.). Among these, carbon black, carbon graphite, etc. are preferred from the viewpoint of having ultraviolet absorbing properties.

[0077] The infrared ablation layer may contain various additives in addition to the binder polymer and infrared absorbing substance described above. Such additives include surfactants, plasticizers, ultraviolet absorbing substances, mold release agents, dyes, pigments, antifoaming agents, perfumes, and the like.

[0078] The method for producing the infrared ablation layer is not particularly limited, but examples thereof include a method in which a resin composition containing the above-mentioned components is prepared and then coated on the above-mentioned intermediate layer.

[0079] The thickness of the infrared ablation layer is preferably 0.1 to 6 μm, and more preferably 0.5 to 3 μm.

[0080] [Cover sheet] The flexographic printing plate precursor of the present invention may have a cover sheet as shown in FIG. Such a cover sheet is not particularly limited, but is preferably a transparent polymer film, and may be a single layer or a laminate of two or more layers. Here, the term "transparent" in the present invention means that the transmittance of visible light is 60% or more, preferably 80% or more, and particularly preferably 90% or more. Examples of polymer film materials include cellulose-based polymers; acrylic polymers containing acrylate ester polymers such as polymethyl methacrylate and lactone ring-containing polymers; thermoplastic norbornene-based polymers; polycarbonate-based polymers; polyester-based polymers such as polyethylene terephthalate, polyethylene naphthalate, and fluorinated polyester polymers; styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers (AS resins); polyolefin-based polymers such as polyethylene, polypropylene, ethylene-propylene copolymers, and polybutadiene; vinyl chloride-based polymers; amide-based polymers such as nylon and aromatic polyamides; imide-based polymers; sulfone-based polymers; polyethersulfone-based polymers; polyetheretherketone-based polymers; polyphenylene sulfide-based polymers; vinylidene chloride-based polymers; vinyl alcohol-based polymers; vinyl butyral-based polymers; arylate-based polymers; polyoxymethylene-based polymers; epoxy-based polymers; or mixtures of these polymers.

[0081] The surface of the cover sheet (the surface on which the infrared ablation layer is formed) may be subjected to a release treatment to reduce adhesion of the infrared ablation layer and improve the releasability of the cover sheet. Examples of such a release treatment include applying a release agent to the surface of the cover sheet to form a release layer. Examples of the release agent include silicone-based release agents and alkyl-based release agents.

[0082] The thickness of the cover sheet is preferably 25 to 250 μm.

[0083] [Flexographic printing plate manufacturing method] The method for producing a flexographic printing plate of the present invention is a method for producing a flexographic printing plate having non-image areas and image areas, comprising the steps of: a mask forming step of forming an image on the infrared ablation layer of the flexographic printing plate precursor of the present invention to form a mask; an exposure step of exposing the photosensitive layer of the flexographic printing plate precursor of the present invention to light imagewise through the mask after the mask formation step; After the exposure step, a development step is carried out using a developer to form non-image areas and image areas.

[0084] [Mask formation process] The mask forming step is a step of forming an image on the infrared ablation layer to form a mask to be used in the exposure step described below. When the infrared ablation layer is irradiated with an infrared laser, heat is generated by the action of the infrared absorbing material, and the infrared ablation layer is removed by the action of the heat, that is, laser ablation occurs. Therefore, by selectively ablating the infrared ablation layer with a laser based on image data, an image mask capable of forming a latent image in the photosensitive layer can be obtained.

[0085] For infrared laser irradiation, an oscillating wavelength in the range of 750 nm to 3000 nm is used. Examples of such lasers include solid-state lasers such as ruby ​​lasers, alexandrite lasers, perovskite lasers, Nd-YAG lasers, and emerald glass lasers; semiconductor lasers such as InGaAsP, InGaAs, and GaAsAl; and dye lasers such as rhodamine dyes. Furthermore, a fiber laser in which these light sources are amplified by a fiber can also be used. Of these, it is preferable to use an exposure light source with an oscillation wavelength of 900 to 1200 nm, and it is more preferable to use a fiber laser, because this increases the sensitivity of the infrared ablation layer.

[0086] [Exposure process] The exposure step is a step of exposing the photosensitive layer to ultraviolet light in an imagewise manner through the mask obtained in the mask formation step. By irradiating the photosensitive layer with ultraviolet light in an imagewise manner, crosslinking and / or polymerization can be induced in the areas irradiated with ultraviolet light, thereby hardening the layer.

[0087] [Development process] The developing step is a step in which development is carried out using a developer to form non-image areas and image areas.

[0088] The developer used in the developing step is not particularly limited, and any conventionally known developer can be used, but from the viewpoint of reducing the environmental load, it is preferable to use a developer containing 50% by mass or more of water (hereinafter also abbreviated as "aqueous developer"). The developer may be either an aqueous solution or a suspension (for example, an aqueous dispersion). The content of water in the aqueous developer is preferably 80 to 99.99% by mass, and more preferably 90 to 99.9% by mass, based on the total mass of the aqueous developer.

[0089] [Rinse process] The method for producing a flexographic printing plate of the present invention preferably includes, after the developing step, a rinsing step in which the surfaces of the non-image areas and image areas formed in the developing step are rinsed with water.

[0090] Examples of rinsing means in the rinsing step include a method of washing with tap water, a method of spraying high-pressure water, and a method of brushing the surfaces of the non-image areas and image areas mainly in the presence of water using a batch-type or conveying-type brush-type washing machine known as a developing machine for flexographic printing plates. [Example]

[0091] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0092] [Example 1] [Preparation of Photosensitive Layer Forming Composition] 63.6 parts by mass of a water-dispersible latex (Nipol LX111NF, a water-dispersible latex of polybutadiene, solids content 55%, manufactured by Zeon Corporation), 10 parts by mass of a telechelic polymer (BAC-45, manufactured by Osaka Organic Chemical Industry Ltd.) (a polybutadiene having acryloyloxy groups at both ends, Mw=10,000), and 8.7 parts by mass of 1,9-nonanediol dimethacrylate (NK Ester NOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.) were mixed, and the water was evaporated for 3 hours in a dryer heated to 60°C to obtain a mixture containing water-dispersible particles. This mixture, 20 parts by mass of butadiene rubber (NF35R, manufactured by Asahi Kasei Corporation), 15 parts by mass of plasticizer (Diana Process Oil PW-32, manufactured by Idemitsu Kosan Co., Ltd.), and 4.4 parts by mass of surfactant (Lapisol A-90, active content 90%, manufactured by NOF Corporation) were kneaded for 45 minutes in a kneader set to 110°C. Thereafter, 0.2 parts by mass of a thermal polymerization inhibitor and 3 parts by mass of a photopolymerization initiator (benzyl dimethyl ketal, manufactured by Tokyo Chemical Industry Co., Ltd.) were added to the kneader and kneaded for 5 minutes to prepare a composition for forming a photosensitive layer.

[0093] [Preparation of composition for forming infrared ablation layer] To 100 parts by weight of a binder polymer consisting of 50 parts by weight of acrylic resin A (Hyperl M5000, Tg: 65°C, manufactured by Negami Chemical Industrial Co., Ltd.) and 50 parts by weight of NBR, 100 parts by weight of carbon black and 3 parts by weight of plasticizer were added, and 812 parts by weight of methyl isobutyl ketone as a solvent was further added and mixed by blade stirring. The resulting mixture was dispersed using a three-roll mill, and then methyl isobutyl ketone was further added to make the solids content 15% by weight, thereby preparing a composition for forming an infrared ablation layer.

[0094] [Preparation of intermediate layer-forming composition] To a total of 100 parts by mass of 50 parts by mass of acrylic resin A (Hyperl M5000, Tg: 65°C, manufactured by Negami Chemical Industrial Co., Ltd.) as the resin component and 50 parts by mass of NBR as the rubber component, 3 parts by mass of plasticizer and 812 parts by mass of methyl isobutyl ketone as a solvent were added and mixed by blade stirring. The resulting mixture was dispersed using a three-roll mill, and then methyl isobutyl ketone was added to adjust the solids content to 15% by mass, thereby preparing a composition for forming an intermediate layer.

[0095] [Preparation of flexographic printing plate precursor] The composition for forming an infrared ablation layer was applied using a bar coater to a 125 μm thick PET film (cover sheet) coated with a silicone-based release agent so that the coating thickness after drying would be 1 μm, and the composition was dried at 120°C for 5 minutes to obtain a laminate X consisting of an infrared ablation layer / cover sheet. Next, the composition for forming an intermediate layer was applied using a bar coater to a 125 μm thick PET film (cover sheet) coated with a silicone-based release agent so that the coating thickness after drying would be 1 μm, and the composition was dried at 120°C for 5 minutes to obtain a laminate Y consisting of an intermediate layer / cover sheet. Next, the surface of this laminate X on which the infrared ablation layer was formed and the surface of laminate Y on which the intermediate layer was formed were laminated together, and pressed using a press heated to 120°C to a thickness of 2 μm, thereby obtaining laminate Z in which the cover sheet, infrared ablation layer, intermediate layer, and cover sheet were laminated in this order. Next, the cover sheet on the surface of the intermediate layer of this laminate Z was peeled off, and the photosensitive layer-forming composition was sandwiched between the adhesive-coated surface of a support formed by applying an adhesive to the surface of a 125 μm thick PET film (substrate), and pressed in a press heated to 120°C so that the thickness of the photosensitive layer-forming composition was 1.5 mm, thereby producing a flexographic printing plate precursor of Example 1 in which the support, photosensitive layer, intermediate layer, infrared ablation layer, and cover sheet were laminated in this order.

[0096] [Examples 2 to 12, Comparative Examples 1 and 2, and Reference Example 1] A flexographic printing plate precursor was produced in the same manner as in Example 1, except that the type and content (mass %) of each component in the intermediate layer was changed as shown in Table 1 below.

[0097] [evaluation] [Microcell reproducibility] The microcell reproducibility of the obtained flexographic printing plate was evaluated by the following method. First, the surface of the solid image area of ​​the flexographic printing plate was measured confocally at 0.1 μm increments in height using a hybrid laser microscope, OPTELICS® HYBRID (manufactured by Lasertec Corporation), with a 50x Apo objective lens (high numerical aperture (NA)). Three-dimensional data was obtained by measuring an area of ​​300 μm in length and 300 μm in width. From the observation image based on the above three-dimensional data, more than 100 convex parts were observed, and the number of parts that were reproduced without any defects was determined. Next, the image reproduction percentage was calculated using the following formula. Image reproduction % = (number of convex parts reproduced without defects) / (number of evaluations) x 100 The evaluation was carried out according to the following criteria, and the results are shown in Table 1 below. To obtain a printed matter with a higher solid density, the image reproduction of the microcell is preferably C to A, more preferably B to A, and even more preferably A. If the image reproduction is less than 80%, the ink transferred to the printed matter will be largely uneven, resulting in a deterioration in the solid density. <Evaluation criteria> A: Image reproduction is 98% or more B: Image reproduction is 90% or more but less than 98% C: Image reproduction is between 80% and 90% D: Image reproduction is less than 80%

[0098] [Suppression of wrinkles in the infrared ablation layer] The cover sheet was peeled off from the prepared flexographic printing plate precursor, and the plate was wrapped around cylindrical tubes with diameters of 170 mm and 130 mm with the infrared ablation layer facing outward and fixed for 10 minutes, after which the tube was removed and allowed to stand on a flat surface for 10 minutes. Thereafter, the surface of the infrared ablation layer was visually observed. The results are shown in the following Table 1. In practice, C to A is preferable, B to A is more preferable, and A is even more preferable. <Evaluation criteria> A: A 130mm diameter tube with no cracks or wrinkles. B: A 170mm diameter tube with no cracks or wrinkles. C: 170mm diameter tube with some wrinkles D: A 170mm diameter tube with cracks and wrinkles.

[0099] [Solid density] The solid density of the obtained flexographic printing plate was evaluated by the following method. The printing machine used was a flexographic printing machine (Taiyo Kikai, TLF-270). The resulting flexographic printing plate was attached to the plate cylinder (drum) using cushion tape (Lohmann) and installed in the printing machine. Then, the kiss touch (the printing pressure at which the entire image begins to adhere) was set to 0 (reference printing pressure), and printing was performed at a printing speed of 150 m / min under the condition of 80 μm pressing from there. The printed substrate used for evaluation was sampled after 5,000 pressings under the above conditions. 50 μm OPP film (Abe Paper Co., Ltd.) was used as the printing substrate. Furthermore, a water-based flexographic ink, Hydric FCF (Dainichiseika Chemicals Co., Ltd.) Cyan, was used as the ink. The density of the solid image area on the printing medium where the microcells were applied was measured using a spectrophotometer eXact (manufactured by X-rite), and evaluated according to the following criteria. The results are shown in the following Table 1. In practice, C to A is preferable, B to A is more preferable, and A is even more preferable. <Evaluation criteria> A: 1.80 or more, 1.90 B: 1.70 or more and less than 1.80 C: 1.60 or more and less than 1.70 D: Less than 1.60

[0100] <Printing durability> The printing durability of the obtained flexographic printing plates was evaluated by the following method. The printing machine used was a flexographic printing machine (TLF-270, manufactured by Taiyo Kikai). The obtained flexographic printing plate was attached to the plate cylinder (drum) using cushion tape (manufactured by Lohmann) and installed in the printing machine. After that, the kiss touch (the printing pressure at which the entire image begins to ink) was set to 0 (standard printing pressure), and printing was carried out at a printing speed of 150 m / min under the condition of pressing down 80 μm from there. The printing substrate used for evaluation was sampled every 5 km up to 25 km under the above conditions. The printing substrate was Aurora Coat 84.9 g / m 2 The ink used was a water-based flexographic ink, Hydric FCF (manufactured by Dainichiseika Chemicals). The number of missing dots in the 2% halftone dot image on the printed material was then counted. The printing distance at which 25 dots were missing out of the 4,746 dots at the start was defined as the end point, and the distance to the end point was evaluated according to the following criteria. The results are shown in the following Table 1. In practice, C to A is preferable, B to A is more preferable, and A is even more preferable. <Evaluation criteria> A: More than 25km B: 20km or more but less than 25km C: 15km or more but less than 20km D: Less than 15km

[0101] [Table 1]

[0102] The ingredients in Table 1 above are shown below. <Infrared ablation layer> NBR: Nipol 1042 (manufactured by Nippon Zeon Co., Ltd.) Acrylic resin A (Tg: 65°C): Hyperl M5000 (manufactured by Negami Chemical Industries, Ltd.) <Middle class> NBR: Nipol 1042 (manufactured by Nippon Zeon Co., Ltd.) BR: NF35R (Asahi Kasei Corporation) SBR: Tufuden 2100 (manufactured by Asahi Kasei Corporation) Acrylic resin A (Tg: 65°C): Hyperl M5000 (manufactured by Negami Chemical Industries, Ltd.) Acrylic resin B (Tg: 85°C): Precoat 200 (manufactured by Negami Chemical Industries, Ltd.) PVA: Kuraray Poval PVA505 (Kuraray) Triphenylphosphine: a reagent manufactured by Tokyo Chemical Industry Co., Ltd. Tris(nonylphenyl)phosphite: a reagent manufactured by Sigma-Aldrich Mica: Synthetic mica Somasif ME-100 (manufactured by Co-op Chemical Co.) <Photosensitive layer> Binder: BR (NF35R, manufactured by Asahi Kasei Corporation) Water-dispersible particles: BR latex (Nipol LX111NF, a water-dispersible polybutadiene latex with a solid content of 55%, manufactured by Zeon Corporation) Oxygen scavenger: Triphenylphosphine (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) Monomer: NK Ester NOD-N (1,9-nonanediol dimethacrylate) (manufactured by Shin-Nakamura Industrial Chemical Co., Ltd.) Photopolymerization initiator: benzyl dimethyl ketal (Tokyo Chemical Industry Co., Ltd.) Polymerization inhibitor: Dibutylhydroxytoluene (Tokyo Chemical Industry Co., Ltd.)

[0103] From the results shown in Table 1 above, it was found that when no intermediate layer was provided, the reproducibility of the microcells was poor and the solid density was also low (Comparative Example 1). Furthermore, when the oxygen blocking layer described in WO 2017 / 056763 was provided as an intermediate layer, it was found that wrinkles occurred in the infrared ablation layer, as described above (Comparative Example 2). Furthermore, when an oxygen scavenger is introduced into the photosensitive layer instead of providing an intermediate layer, it is found that the occurrence of wrinkles in the infrared ablation layer is suppressed and the reproducibility of microcells is good when made into a flexographic printing plate, but printing durability is poor and it is difficult to put this into practical use (Reference Example 1).

[0104] In contrast, it was found that providing an intermediate layer containing a rubber component and a resin component, with the resin component containing at least one of an acrylic resin and a methacrylic resin, suppresses the occurrence of wrinkles in the infrared ablation layer and improves the reproducibility of microcells when made into a flexographic printing plate (Examples 1 to 12).The solid density and printing durability of Examples 1 to 12 were at a level that could be used in practical applications. Furthermore, by comparing Example 1 with Examples 6 to 11, it was found that when the intermediate layer further contains at least one of an oxygen scavenger and inorganic layered particles, the reproducibility of microcells becomes better when the resulting flexographic printing plate is made, and the solid density is improved. Furthermore, a comparison of Examples 1 to 5 revealed that when the mass ratio of the rubber component to the resin component (rubber component / resin component) was within the range of 1 / 3 to 3 / 1, the occurrence of wrinkles in the infrared ablation layer could be further suppressed. Furthermore, a comparison between Example 1 and Example 12 revealed that when the glass transition temperature (Tg) of the resin component contained in the intermediate layer is 48 to 80°C, the occurrence of wrinkles in the infrared ablation layer can be further suppressed. [Explanation of symbols]

[0105] 1 Support 2 Photosensitive layer 3. Middle class 4. Infrared ablation layer 5 Cover Sheet 10 Flexographic printing plate precursor

Claims

1. A flexographic printing plate precursor having, in this order, a support, a photosensitive layer, an intermediate layer, and an infrared ablation layer, the intermediate layer contains a rubber component and a resin component, The flexographic printing plate precursor, wherein the resin component contains at least one of an acrylic resin and a methacrylic resin.

2. The flexographic printing plate precursor according to claim 1 , wherein the intermediate layer further contains at least one of an oxygen scavenger and inorganic layered particles.

3. The flexographic printing plate precursor according to claim 2, wherein the oxygen scavenger is at least one compound selected from the group consisting of phosphite compounds, phosphine compounds, and thioether compounds.

4. 3. The flexographic printing plate precursor according to claim 2, wherein the inorganic layered particles are at least one selected from the group consisting of mica, talc, taeniolite, montmorillonite, saponite, hectorite, and zirconium phosphate.

5. The flexographic printing plate precursor according to any one of claims 1 to 4, wherein the resin component has a glass transition temperature of 48 to 80°C.

6. The flexographic printing plate precursor according to any one of claims 1 to 5, wherein a mass ratio of the rubber component to the resin component is in the range of 1 / 3 to 3 / 1.

7. 1. A method for producing a flexographic printing plate having non-image areas and image areas, comprising: a mask forming step of forming an image on an infrared ablation layer of the flexographic printing plate precursor according to any one of claims 1 to 6 to form a mask; an exposure step of exposing a photosensitive layer of the flexographic printing plate precursor to light in an imagewise manner through the mask after the mask formation step; A method for producing a flexographic printing plate, comprising, after the exposure step, a development step of developing with a developer to form non-image areas and image areas.

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