Flexographic printing plate precursor and method for producing flexographic printing plate

Abstract

The present invention addresses the problem of providing: a flexographic printing plate precursor which, when formed into a flexographic printing plate, has good reproducibility of microcells and also has good durability of individual dots; and a method for producing a flexographic printing plate using the flexographic printing plate precursor. This flexographic printing plate precursor has, in this order, a support, a photosensitive resin layer, and an infrared ablative layer, wherein the photosensitive resin layer contains a photopolymerization initiator represented by a predetermined formula (1) and a photopolymerization initiator represented by a predetermined formula (2).

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 flexographic printing plate precursor. Background Art

[0002] The original plate of a flexographic printing plate generally comprises a photosensitive resin layer (photosensitive layer) composed of a photosensitive resin composition on a support composed of a polyester film, etc. The flexographic printing plate is produced by exposing a predetermined image on the surface of the photosensitive resin layer of the original plate and then removing the resin in the unexposed portion.

[0003] In the case of a so-called analog flexographic printing plate precursor, a negative film on which a predetermined image has been formed is placed on a photosensitive resin layer, and a predetermined image is exposed on the surface of the photosensitive resin layer through the negative film.

[0004] In contrast, in the LAM (Laser ablation mask) method flexographic printing plate original, an infrared ablation layer is pre-set on the photosensitive resin layer, and a digitized negative image information is directly drawn on the infrared ablation layer using an infrared laser to produce the desired negative pattern. After that, a specified image is exposed on the surface of the photosensitive resin layer through the negative pattern.

[0005] As such a LAM-based flexographic printing plate precursor, for example, Patent Document 1 describes a flexographic printing plate precursor in which a support, a photosensitive resin layer, and an infrared ablative layer are stacked.

[0006] Previous technical literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2012-137515 Summary of the invention

[0009] Technical issues to be solved by the invention

[0010] With respect to the known flexographic printing plate precursor described in Patent Document 1, etc., the inventors attempted to form a fine concave-convex pattern (hereinafter also referred to as "microunit") on the surface of the image portion of the flexographic printing plate from the viewpoint of improving the ink transferability when the flexographic printing plate is made.

[0011] Furthermore, the inventors have found that, in a flexographic printing plate original in which microunits are easily formed on the surface of the image portion of the flexographic printing plate, gaps or folds are generated in independent image portions (hereinafter also referred to as "independent dots") having a diameter of about 100 to 1000 μm, regardless of whether microunits are formed or not.

[0012] Therefore, the present invention aims to provide a flexographic printing plate precursor having good reproducibility of microunits and good durability of independent small dots when a flexographic printing plate is produced, and a method for producing a flexographic printing plate using the flexographic printing plate precursor.

[0013] Means for solving technical problems

[0014] As a result of intensive research conducted by the present inventors to achieve the above-mentioned problems, it was discovered that, for a flexographic printing plate original having a support, a photosensitive resin layer and an infrared ablation layer in sequence, by making the photosensitive resin layer contain a photopolymerization initiator represented by formula (1) described later and a photopolymerization initiator represented by formula (2) described later, the reproducibility of microunits becomes good when the flexographic printing plate is made, and the durability of independent small dots also becomes good, thereby completing the present invention.

[0015] That is, the present inventors have found that the above-mentioned subject can be achieved by the following configuration.

[0016] [1] A flexographic printing plate precursor comprising, in order, a support, a photosensitive resin layer, and an infrared ablation layer, wherein:

[0017] The photosensitive resin layer contains a photopolymerization initiator represented by the formula (1) described below and a photopolymerization initiator represented by the formula (2) described below.

[0018] [2] The flexographic printing plate precursor according to [1], wherein

[0019] The photosensitive resin layer further contains a photopolymerization initiator represented by the formula (3) described later.

[0020] [3] The flexographic printing plate precursor according to [1] or [2], wherein

[0021] The photosensitive resin layer contains water-dispersible particles.

[0022] [4] A method for manufacturing a flexographic printing plate, the flexographic printing plate having a non-image area and an image area, the method for manufacturing a flexographic printing plate comprising:

[0023] A mask forming step of forming a mask by forming an image on the infrared ablative layer of the flexographic printing plate precursor according to any one of [1] to [3];

[0024] an exposure step of exposing the photosensitive resin layer of the flexographic printing plate precursor to an image through the mask after the mask forming step; and

[0025] In the development step, after the exposure step, development is performed using a developer to form a non-image area and an image area.

[0026] Effects of the Invention

[0027] According to the present invention, it is possible to provide a flexographic printing plate precursor having good reproducibility of microunits and good durability of independent small dots when a flexographic printing plate is produced, and a method for producing a flexographic printing plate using the flexographic printing plate precursor. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic cross-sectional view showing an example of the flexographic printing plate precursor of the present invention. DETAILED DESCRIPTION

[0029] Hereinafter, the present invention will be described in detail.

[0030] Although the description of the constituent elements described below may be made based on representative embodiments of the present invention, the present invention is not limited to such embodiments.

[0031] In addition, in this specification, the numerical range expressed with "to" means the range which includes the numerical value described before and after "to" as a lower limit value and an upper limit value.

[0032] In addition, in this specification, each component can use one substance corresponding to each component alone, or can use two or more substances simultaneously. Here, regarding each component, when two or more substances are used simultaneously, unless otherwise specified, the content of the component refers to the total content of the substances used simultaneously.

[0033] In addition, in this specification, "(meth)acrylic acid" is an expression which means "acrylic acid" or "methacrylic acid", and "(meth)acryloyl" is an expression which means "acryloyl" or "methacryloyl".

[0034] Furthermore, in the present specification, examples of substituents include substituents described in the substituent group A described below.

[0035] In the present specification, the phrase “may have a substituent” includes not only an embodiment having no substituent but also an embodiment having one or more substituents.

[0036] <Substituent Group A>

[0037] As the substituent, for example, there can be mentioned:

[0038] a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, preferably a chlorine atom, a fluorine atom, more preferably a fluorine atom);

[0039] Alkyl group (preferably a linear, branched or cyclic alkyl group having 1 to 48 carbon atoms, more preferably a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms, for example, a linear alkyl group having 1 to 6 carbon atoms (for example, methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl), a branched alkyl group having 3 to 6 carbon atoms (for example, isopropyl, isobutyl, tert-butyl, sec-butyl, neopentyl, isohexyl, 3-methylpentyl), a cyclic alkyl group having 3 to 12 carbon atoms (for example, cyclopropyl, cyclopentyl, cyclohexyl, 1-norbornyl, 1-adamantyl));

[0040] alkenyl (preferably an alkenyl group having 2 to 48 carbon atoms, more preferably an alkenyl group having 2 to 18 carbon atoms, for example, vinyl, allyl, 1-butenyl, 2-butenyl);

[0041] Alkynyl (preferably an alkynyl group having 2 to 6 carbon atoms, more preferably an alkynyl group having 2 to 4 carbon atoms, for example, ethynyl, 1-propynyl, propargyl, 1-butynyl, 2-butynyl);

[0042] Aryl group (preferably an aryl group having 6 to 48 carbon atoms, more preferably an aryl group having 6 to 24 carbon atoms, for example, phenyl, oligoaryl (naphthyl, anthracenyl), phenanthrenyl, fluorenyl, pyrenyl, triphenylenyl, biphenyl);

[0043] Heteroaryl (preferably a heteroatom-containing cyclic group having 1 to 32 carbon atoms, more preferably 1 to 18 carbon atoms, for example, 2-thienyl, 4-pyridyl, 2-furyl, 2-pyrimidinyl, 1-pyridyl, 2-benzothiazolyl, 1-imidazolyl, 1-pyrazolyl, benzotriazol-1-yl);

[0044] Aralkyl (preferably an aralkyl group having 7 to 15 carbon atoms, for example, benzyl, phenethyl, methylbenzyl, phenylpropyl, 1-methylphenylethyl, phenylbutyl, 2-methylphenylpropyl, tetrahydronaphthyl, naphthylmethyl, naphthylethyl, indenyl, fluorenyl, anthracenemethyl (anthracenylmethyl), phenanthracenemethyl (phenanthrenylmethyl));

[0045] Silyl group (preferably a silyl group having 3 to 38 carbon atoms, more preferably a silyl group having 3 to 18 carbon atoms, for example, trimethylsilyl, triethylsilyl, tributylsilyl, tert-butyldimethylsilyl, tert-hexyldimethylsilyl);

[0046] Hydroxyl; cyano; nitro; morpholino;

[0047] an alkoxy group (preferably an alkoxy group having 1 to 48 carbon atoms, more preferably an alkoxy group having 1 to 24 carbon atoms, for example, a methoxy group, an ethoxy group, a 1-butoxy group, a 2-butoxy group, an isopropoxy group, a tert-butoxy group, a dodecyloxy group, a cycloalkyloxy group (for example, a cyclopentyloxy group, a cyclohexyloxy group));

[0048] An aryloxy group (preferably an aryloxy group having 6 to 48 carbon atoms, more preferably an aryloxy group having 6 to 24 carbon atoms, for example, a phenoxy group and a 1-naphthyloxy group);

[0049] an alkenyloxy group (preferably an alkenyloxy group having 2 to 6 carbon atoms, for example, vinyloxy, 1-propenyloxy, 2-n-propenyloxy (allyloxy), 1-n-butenyloxy, isopreneoxy);

[0050] A heteroatom-containing epoxy group (preferably one having 1 to 32 carbon atoms, more preferably one having 1 to 18 carbon atoms, for example, 1-phenyltetrazol-5-oxyl group and 2-tetrahydropyranyloxy group);

[0051] A silyloxy group (preferably a silyloxy group having 1 to 32 carbon atoms, more preferably a silyloxy group having 1 to 18 carbon atoms, for example, a trimethylsilyloxy group, a tert-butyldimethylsilyloxy group, and a diphenylmethylsilyloxy group);

[0052] an acyloxy group (preferably an acyloxy group having 2 to 48 carbon atoms, more preferably an acyloxy group having 2 to 24 carbon atoms, for example, an acetoxy group, a pivaloyloxy group, a benzoyloxy group, a dodecanoyloxy group, an acryloyloxy group, or a methacryloyloxy group);

[0053] A hydroxyalkyleneoxy group (preferably a hydroxyalkyleneoxy group having 2 to 10 carbon atoms, for example, a hydroxyethyleneoxy group);

[0054] an alkoxycarbonyloxy group (preferably an alkoxycarbonyloxy group having 2 to 48 carbon atoms, more preferably an alkoxycarbonyloxy group having 2 to 24 carbon atoms, for example, an ethoxycarbonyloxy group, a tert-butoxycarbonyloxy group, a cycloalkoxycarbonyloxy group (for example, a cyclohexyloxycarbonyloxy group));

[0055] An aryloxycarbonyloxy group (preferably an aryloxycarbonyloxy group having 7 to 32 carbon atoms, more preferably an aryloxycarbonyloxy group having 7 to 24 carbon atoms, for example, a phenoxycarbonyloxy group);

[0056] A carbamoyloxy group (preferably a carbamoyloxy group having 1 to 48 carbon atoms, more preferably a carbamoyloxy group having 1 to 24 carbon atoms, for example, N,N-dimethylcarbamoyloxy, N-butylcarbamoyloxy, N-phenylcarbamoyloxy, N-ethyl-N-phenylcarbamoyloxy);

[0057] A sulfamoyloxy group (preferably a sulfamoyloxy group having 1 to 32 carbon atoms, more preferably a sulfamoyloxy group having 1 to 24 carbon atoms, for example, N,N-diethylsulfamoyloxy group and N-propylsulfamoyloxy group);

[0058] an alkylsulfonyloxy group (preferably an alkylsulfonyloxy group having 1 to 38 carbon atoms, more preferably an alkylsulfonyloxy group having 1 to 24 carbon atoms, for example, a methylsulfonyloxy group, a hexadecylsulfonyloxy group, and a cyclohexylsulfonyloxy group);

[0059] an arylsulfonyloxy group (preferably an arylsulfonyloxy group having 6 to 32 carbon atoms, more preferably an arylsulfonyloxy group having 6 to 24 carbon atoms, for example, a phenylsulfonyloxy group);

[0060] acyl group (preferably an acyl group having 1 to 48 carbon atoms, more preferably an acyl group having 1 to 24 carbon atoms, for example, formyl, acetyl, acryloyl, methacryloyl, pivaloyl, benzoyl, tetradecanoyl, cyclohexanoyl);

[0061] an alkoxycarbonyl group (preferably an alkoxycarbonyl group having 2 to 48 carbon atoms, more preferably an alkoxycarbonyl group having 2 to 24 carbon atoms, for example, a methoxycarbonyl group, an ethoxycarbonyl group, an octadecyloxycarbonyl group, a cyclohexyloxycarbonyl group, and a 2,6-di-tert-butyl-4-methylcyclohexyloxycarbonyl group);

[0062] an aryloxycarbonyl group (preferably an aryloxycarbonyl group having 7 to 32 carbon atoms, more preferably an aryloxycarbonyl group having 7 to 24 carbon atoms, for example, a phenoxycarbonyl group);

[0063] Carbamoyl (preferably a carbamoyl group having 1 to 48 carbon atoms, more preferably a carbamoyl group having 1 to 24 carbon atoms, for example, carbamoyl, N,N-diethylcarbamoyl, N-ethyl-N-octylcarbamoyl, N,N-dibutylcarbamoyl, N-propylcarbamoyl, N-phenylcarbamoyl, N-methyl-N-phenylcarbamoyl, N,N-dicyclohexylcarbamoyl);

[0064] An amino group (preferably an amino group having 32 or less carbon atoms, more preferably an amino group having 24 or less carbon atoms, for example, amino, methylamino, N,N-dibutylamino, tetradecylamino, 2-ethylhexylamino, and cyclohexylamino);

[0065] Anilino (preferably anilino having 6 to 32 carbon atoms, more preferably anilino having 6 to 24 carbon atoms, for example, anilino and N-methylanilino);

[0066] A heteroatom-containing cyclic amino group (preferably a heteroatom-containing cyclic amino group having 1 to 32 carbon atoms, more preferably 1 to 18 carbon atoms, for example, 4-pyridylamino group);

[0067] Carboxamide (preferably a carboxamide having 2 to 48 carbon atoms, more preferably a carboxamide having 2 to 24 carbon atoms, for example, acetamide, benzamide, tetradecanoylamide, pivaloylamide, cyclohexaneamide);

[0068] A urea group (preferably a urea group having 1 to 32 carbon atoms, more preferably a urea group having 1 to 24 carbon atoms, for example, a urea group, an N,N-dimethylurea group, an N-phenylurea group);

[0069] An imide group (preferably an imide group having 36 or less carbon atoms, more preferably an imide group having 24 or less carbon atoms, for example, an N-succinimide group, an N-phthalimide group);

[0070] an alkoxycarbonylamino group (preferably an alkoxycarbonylamino group having 2 to 48 carbon atoms, more preferably an alkoxycarbonylamino group having 2 to 24 carbon atoms, for example, methoxycarbonylamino, ethoxycarbonylamino, tert-butoxycarbonylamino, octadecyloxycarbonylamino, and cyclohexyloxycarbonylamino);

[0071] An aryloxycarbonylamino group (preferably an aryloxycarbonylamino group having 7 to 32 carbon atoms, more preferably an aryloxycarbonylamino group having 7 to 24 carbon atoms, for example, a phenoxycarbonylamino group);

[0072] Sulfonamide (preferably a sulfonamide having 1 to 48 carbon atoms, more preferably a sulfonamide having 1 to 24 carbon atoms, for example, methanesulfonamide, butanesulfonamide, benzenesulfonamide, hexadecanesulfonamide, cyclohexanesulfonamide);

[0073] a sulfamoylamino group (preferably a sulfamoylamino group having 1 to 48 carbon atoms, more preferably a sulfamoylamino group having 1 to 24 carbon atoms, for example, N,N-dipropylsulfamoylamino group and N-ethyl-N-dodecylsulfamoylamino group);

[0074] an azo group (preferably an azo group having 1 to 32 carbon atoms, more preferably an azo group having 1 to 24 carbon atoms, for example, a phenylazo group and a 3-pyrazolylazo group);

[0075] an alkylthio group (preferably an alkylthio group having 1 to 48 carbon atoms, more preferably an alkylthio group having 1 to 24 carbon atoms, for example, methylthio, ethylthio, octylthio, cyclohexylthio);

[0076] an arylthio group (preferably an arylthio group having 6 to 48 carbon atoms, more preferably an arylthio group having 6 to 24 carbon atoms, for example, a phenylthio group);

[0077] a heteroatom-containing cyclic sulfhydryl group (preferably a heteroatom-containing cyclic sulfhydryl group having 1 to 32 carbon atoms, more preferably a heteroatom-containing cyclic sulfhydryl group having 1 to 18 carbon atoms, for example, a 2-benzothiazolylsulfyl group, a 2-pyridylsulfyl group, and a 1-phenyltetrazolylsulfyl group);

[0078] an alkylsulfinyl group (preferably an alkylsulfinyl group having 1 to 32 carbon atoms, more preferably an alkylsulfinyl group having 1 to 24 carbon atoms, for example, dodecanesulfinyl group);

[0079] an arylsulfinyl group (preferably an arylsulfinyl group having 6 to 32 carbon atoms, more preferably an arylsulfinyl group having 6 to 24 carbon atoms, for example, a phenylsulfinyl group);

[0080] an alkylsulfonyl group (preferably an alkylsulfonyl group having 1 to 48 carbon atoms, more preferably an alkylsulfonyl group having 1 to 24 carbon atoms, for example, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, isopropylsulfonyl, 2-ethylhexylsulfonyl, hexadecylsulfonyl, octylsulfonyl, and cyclohexylsulfonyl);

[0081] an arylsulfonyl group (preferably an arylsulfonyl group having 6 to 48 carbon atoms, more preferably an arylsulfonyl group having 6 to 24 carbon atoms, for example, a phenylsulfonyl group and a 1-naphthylsulfonyl group);

[0082] a sulfamoyl group (preferably a sulfamoyl group having 32 or less carbon atoms, more preferably a sulfamoyl group having 24 or less carbon atoms, for example, a sulfamoyl group, N,N-dipropylsulfamoyl group, N-ethyl-N-dodecylsulfamoyl group, N-ethyl-N-phenylsulfamoyl group, N-cyclohexylsulfamoyl group, and N-(2-ethylhexyl)sulfamoyl group);

[0083] a phosphonyl group (preferably a phosphonyl group having 1 to 32 carbon atoms, more preferably a phosphonyl group having 1 to 24 carbon atoms, for example, a phenoxyphosphonyl group, an octyloxyphosphonyl group, a phenylphosphonyl group);

[0084] A phosphinylamino group (preferably a phosphinylamino group having 1 to 32 carbon atoms, more preferably a phosphinylamino group having 1 to 24 carbon atoms, for example, an ethoxyphosphinylamino group and a dioctyloxyphosphinylamino group);

[0085] Epoxy; -NHCOCH 3 ;-SO 2 NHC 2 H 4 OCH 3 ;-NHSO 2 CH 3 ;

[0086] Etc., these can be combined into 2 or more.

[0087] These substituents may be further substituted by these substituents. Furthermore, when there are two or more substituents, they may be the same or different. Furthermore, when possible, they may be bonded to each other to form a ring.

[0088] 〔Flexographic printing plate original〕

[0089] The flexographic printing plate precursor of the present invention is a flexographic printing plate precursor having a support, a photosensitive resin layer, and an infrared ablative layer in this order.

[0090] Furthermore, in the flexographic printing plate precursor of the present invention, the photosensitive resin layer contains a photopolymerization initiator represented by the formula (1) described below and a photopolymerization initiator represented by the formula (2) described below.

[0091] Figure 1This is a schematic cross-sectional view showing an example of the flexographic printing plate precursor of the present invention.

[0092] Figure 1 The flexographic printing plate precursor 10 shown includes a support 1 , a photosensitive resin layer 2 , and an infrared ablative layer 3 in this order.

[0093] And, if Figure 1 As shown, the flexographic printing plate precursor of the present invention may have a cover sheet 4 .

[0094] Hereinafter, the structure of each layer of the flexographic printing plate precursor of the present invention will be described in detail.

[0095] 〔Supporting body〕

[0096] The material of the support possessed by the flexographic printing plate precursor used in the present invention is not particularly limited, but it is preferred to use a material with high dimensional stability, for example, metals such as steel, stainless steel, and aluminum; polyesters (such as 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; plastic resins reinforced with glass fiber (epoxy resin or phenolic resin, etc.); cloth, paper, etc.

[0097] The support is preferably a polymer film or cloth, and more preferably a polymer film, from the viewpoint of dimensional stability and easy availability. The form of the support is determined by whether the polymer layer is in a sheet or sleeve shape.

[0098] As the cloth, there can be used a plain or twill weave of natural fibers such as cotton, linen, silk, and wool, or a synthetic fiber such as acetate, vinylon, vinylidene, polyvinyl chloride, acrylic, polypropylene, polyethylene, polyurethane, fluorine-based filaments, polyacrylate, rayon, nylon, polyamide, and polyester, or a cloth in the form of various woven fabrics or a non-woven fabric.

[0099] 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 or phenolic resins, etc.). Among these, polyester films are preferred from the viewpoint of dimensional stability, etc.

[0100] Examples of the polyester film include PET film, PBT film, and PEN film. From the viewpoint of dimensional stability and the like, a PET (polyethylene terephthalate) film is preferred.

[0101] The film thickness of the support is not particularly limited, but is preferably 5 to 3000 μm, more preferably 50 to 2000 μm, and even more preferably 100 to 1000 μm from the viewpoint of dimensional stability and handleability.

[0102] [Photosensitive resin layer]

[0103] <Photopolymerization initiator represented by formula (1)>

[0104] The photosensitive resin layer of the flexographic printing plate precursor of the present invention contains a photopolymerization initiator represented by the following formula (1).

[0105] [Chemical formula 1]

[0106]

[0107] In the above formula (1), n ​​represents 1 or 2, and preferably represents 1.

[0108] In the above formula (1), X 1 and X 2 Each independently represents a hydrogen atom or -OR 1 A substituent other than the group represented by R 1 represents a hydrogen atom or a substituent,

[0109] Here, as R 1 The substituent represented by one embodiment of the present invention includes the substituents described in the above substituent group A, among which an alkyl group is preferred, and a linear alkyl group having 1 to 6 carbon atoms is more preferred. 1 The group represented by is preferably an alkoxy group.

[0110] And, as X 1 and X 2 In one way, except for -OR 1 The substituents other than the group represented by include the substituents described in the above-mentioned substituent group A except for -OR 1 Among them, the group other than the group represented by is preferably an alkyl group, and more preferably a linear alkyl group having 1 to 6 carbon atoms.

[0111] And, X 1 and X 2 The ring may be linked to each other to form a ring. Here, as the ring formed, for example, a cycloalkane ring can be mentioned, among which a cyclohexane ring is preferred. In addition, as atoms constituting the ring, a heteroatom may be present.

[0112] In addition, when n in the above formula (1) is 2, a plurality of X 1 Can be the same or different, multiple X 2 They may be the same or different.

[0113] In the above formula (1), when n is 1, X 3 represents a hydrogen atom or a substituent, and is preferably a hydrogen atom.

[0114] Here, when n is 1, 3 The substituent represented by one embodiment of includes the substituents described in the above substituent group A, among which a hydroxyalkyleneoxy group is preferred, and a hydroxyethyleneoxy group is more preferred.

[0115] In the above formula (1), when n is 2, X 3 represents a single bond or a divalent linking group, and is preferably a divalent linking group.

[0116] Here, when n is 2, 3 The divalent linking group represented by one embodiment of the present invention includes a divalent hydrocarbon group which may have a substituent, etc. In addition, one or more -CH 2 - may be substituted by -O-, -S-, -NH-, -N(Q)- or -CO-. Q represents a hydrogen atom or a substituent.

[0117] Examples of the divalent hydrocarbon group include divalent aliphatic hydrocarbon groups such as an alkylene group having 1 to 10 carbon atoms, an alkenylene group having 1 to 10 carbon atoms, and an alkynylene group having 1 to 10 carbon atoms, and divalent aromatic hydrocarbon groups such as an arylene group.

[0118] As the photopolymerization initiator represented by the above formula (1), for example, compounds represented by the following formulas (1-1) to (1-4) can be cited. In addition, the compounds represented by the following formulas (1-1) to (1-3) are exemplary compounds when n in the above formula (1) is 1, and the compound represented by the following formula (1-4) is an exemplary compound when n in the above formula (1) is 2.

[0119] [Chemical formula 2]

[0120]

[0121] In the present invention, the content of the photopolymerization initiator represented by the formula (1) is preferably 0.5 to 20% by mass, more preferably 1 to 10% by mass, and even more preferably 2 to 5% by mass based on the total mass of the solid content of the photosensitive resin layer.

[0122] <Photopolymerization initiator represented by formula (2)>

[0123] The photosensitive resin layer of the flexographic printing plate precursor of the present invention contains a photopolymerization initiator represented by the following formula (2).

[0124] [Chemical formula 3]

[0125]

[0126] In the above formula (2), Y 1 and Y 2 Each independently represents a hydrogen atom or -OR 1 A substituent other than the group represented by R 1 represents a hydrogen atom or a substituent,

[0127] Here, as R 1 The substituent represented by one embodiment of the present invention includes the substituents described in the above substituent group A, among which an alkyl group is preferred, and a linear alkyl group having 1 to 6 carbon atoms is more preferred. 1 The group represented by is preferably an alkoxy group.

[0128] And, as Y 1 and Y 2 In one way, except for -OR 1 The substituents other than the group represented by include the substituents described in the above-mentioned substituent group A except for -OR 1 Among them, the group other than the group represented by is preferably an alkyl group or an aralkyl group, and more preferably a linear alkyl group having 1 to 6 carbon atoms or a benzyl group.

[0129] And, Y 1 and Y 2 They can be connected to each other to form a ring.

[0130] In the above formula (2), Y 3 represents a hydrogen atom or a substituent, and preferably represents a substituent.

[0131] Here, as Y 3 The substituent represented by one embodiment of the present invention includes the substituents described in the above substituent group A, and among them, an alkylthio group or a morpholino group is preferred.

[0132] In the above formula (2), Y 4 and Y 5 Each independently represents a hydrogen atom or a substituent, and preferably represents a substituent.

[0133] Here, as Y 4 and Y 5 The substituent represented by one embodiment of includes the substituents described in the above substituent group A, among which an alkyl group is preferred, and a linear alkyl group having 1 to 6 carbon atoms is more preferred.

[0134] And, Y 4 and Y 5 Here, as the ring formed, as long as it has Y 4 and Y 5 The ring to which the nitrogen atom is bonded is not particularly limited, and examples thereof include morpholine ring, pyrrole ring, pyridine ring, imidazole ring, benzopyrrole ring, benzimidazole ring, thiazole ring, oxazole ring, etc. In addition, the ring may further contain heteroatoms other than the nitrogen atom as atoms constituting the ring.

[0135] Examples of the photopolymerization initiator represented by the above formula (2) include compounds represented by the following formulas (2-1) to (2-2).

[0136] [Chemical formula 4]

[0137]

[0138] In the present invention, the content of the photopolymerization initiator represented by the formula (2) is preferably 0.5 to 15% by mass, more preferably 0.7 to 10% by mass, and even more preferably 1 to 3% by mass based on the total mass of the solid content of the photosensitive resin layer.

[0139] Furthermore, in the present invention, from the perspective of achieving a good balance between the reproducibility of microunits and the durability of independent dots when making a flexographic printing plate, the content of the photopolymerization initiator represented by the above formula (2) is preferably less than 50% by mass, and more preferably 25 to 45% by mass, relative to the total mass of the photopolymerization initiator represented by the above formula (1) and the photopolymerization initiator represented by the above formula (2).

[0140] <Other photopolymerization initiators>

[0141] In the present invention, the photosensitive resin layer preferably further contains a photopolymerization initiator represented by the following formula (3) because the reproducibility of micro units is improved when the flexographic printing plate is prepared and the durability of independent small dots is also improved.

[0142] [Chemical formula 5]

[0143]

[0144] In the above formula (3), Z 1 and Z 2 Each independently represents a hydrogen atom or a substituent, and preferably represents a substituent.

[0145] Here, as Z 1 and Z 2The substituent represented by one embodiment of includes the substituents described in the above substituent group A, among which an alkyl group is preferred, and a linear alkyl group having 1 to 6 carbon atoms is more preferred.

[0146] In the above formula (3), Z 3 represents a hydrogen atom or a substituent, and preferably represents a hydrogen atom.

[0147] Here, as Z 3 The substituent represented by one embodiment of includes the substituents described in the above substituent group A, among which an alkyl group is preferred, and a linear alkyl group having 1 to 6 carbon atoms is more preferred.

[0148] In the above formula (3), Z 4 represents a substituent.

[0149] Here, as Z 4 The substituent represented by includes the substituents described in the above substituent group A, among which an aryl group is preferred, and a phenyl group is more preferred.

[0150] Examples of the photopolymerization initiator represented by the above formula (3) include compounds represented by the following formula (3-1).

[0151] [Chemical formula 6]

[0152]

[0153] In the present invention, the content of the photopolymerization initiator represented by the formula (3) is preferably 3% by mass or less, more preferably 2% by mass or less, and further preferably 0.5 to 1.5% by mass, based on the total mass of the solid content of the photosensitive resin layer.

[0154] The photosensitive resin layer of the flexographic printing plate precursor of the present invention preferably contains water-dispersible particles, a binder, a monomer, and a polymerization inhibitor in addition to the above-mentioned photopolymerization initiator.

[0155] <Water-dispersible particles>

[0156] The water-dispersible particles are not particularly limited, but are preferably polymers because the reproducibility of the microunits becomes better when the flexographic printing plate is made, and the durability of the independent small dots becomes better. Hereinafter, "the reproducibility of the microunits becomes better when the flexographic printing plate is made, and the durability of the independent small dots becomes better" is also referred to as "the effects of the present invention, etc. are more excellent".

[0157] Specific examples of the above-mentioned polymers include diene polymers (for example, polybutadiene, natural rubber, styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, methyl methacrylate-butadiene copolymers, polychloroprene, polyisoprene), polyurethanes, vinylpyridine polymers, butyl polymers, thiol polymers, acrylate polymers, polymers obtained by copolymerizing these polymers with other components such as acrylic acid and methacrylic acid, and the like. These may be used alone or in combination of two or more.

[0158] 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, acrylate and methacrylate, and is more preferably polybutadiene, because it has better water-based ink resistance.

[0159] The above-mentioned polymer is preferably a polymer having no reactive functional group (for example, (meth)acryloyloxy group) at both ends.

[0160] The polymer is preferably a polymer obtained by removing water from a water-dispersible latex because the effects of the present invention are more excellent. Specific examples of the water-dispersible latex include the water-dispersible latexes of the specific examples of the polymers described above.

[0161] 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 based on the total mass of the solid content of the photosensitive resin layer, because the effects of the present invention are more excellent.

[0162] <Adhesive>

[0163] The binder is not particularly limited, and examples thereof include thermoplastic polymers and the like.

[0164] The thermoplastic polymer is not particularly limited as long as it is a thermoplastic polymer, and specific examples thereof include polystyrene resins, polyester resins, polyamide resins, polysulfone resins, polyethersulfone resins, polyimide resins, acrylic resins, acetal resins, epoxy resins, polycarbonate resins, rubbers, thermoplastic elastomers, etc. These may be used alone or in combination of two or more.

[0165] Among these, rubber and thermoplastic elastomer are preferred because they can easily form a soft and flexible film, rubber is more preferred, and diene rubber is further preferred.

[0166] As the rubber, in order to ensure the elasticity of the flexographic plate, a non-fluid rubber having no fluidity is preferred.

[0167] Specifically, for example, butadiene rubber (BR), nitrile rubber (NBR), acrylic rubber, epichlorohydrin rubber, polyurethane rubber, isoprene rubber, styrene isoprene rubber, styrene butadiene rubber (SBR), ethylene-propylene copolymer, and chlorinated polyethylene, etc., can be used alone or in combination of two or more. Among these, from the viewpoint of better water developability and drying properties and image reproducibility, at least one rubber selected from the group consisting of butadiene rubber (BR), styrene butadiene rubber (SBR), and nitrile rubber (NBR) is preferred, and from the viewpoint of water-based ink resistance, butadiene rubber and styrene butadiene rubber are more preferred.

[0168] Examples of the thermoplastic elastomer include PB (polybutadiene-based thermoplastic elastomer), polyisoprene-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, and acrylic-based thermoplastic elastomer. Specifically, examples include SB (polystyrene-polybutadiene), SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), SBS (polystyrene-polyethylene / polybutylene-polystyrene), ABS (acrylonitrile butadiene styrene copolymer), ACM (acrylic rubber), ACS (acrylonitrile chlorinated polyethylene styrene copolymer), acrylonitrile styrene copolymer, syndiotactic 1,2-polybutadiene, polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate, and the like. Among these, PB, SBS, and SIS are particularly preferred because of their improved water-developable properties and from the perspectives of drying properties and image reproducibility.

[0169] The content of the binder is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, and even more preferably 7 to 30% by mass, relative to the total mass of the solid content of the photosensitive resin layer.

[0170] <Single>

[0171] The monomers are not particularly limited, but it is preferred to use a monofunctional monomer and a bifunctional monomer simultaneously because the effects of the present invention are more excellent.

[0172] (Monofunctional monomer)

[0173] The monofunctional monomer is preferably a compound having one ethylenically unsaturated group because the effects of the present invention and the like are more excellent.

[0174] Examples of the ethylenically unsaturated group include radical polymerizable groups including acryloyl, methacryloyl, vinyl, styryl, and allyl groups. Among them, acryloyl, methacryloyl, and C(O)OCH=CH 2 , more preferably acryloyl and methacryloyl.

[0175] Examples of the compound having one ethylenically unsaturated group include

[0176] N-vinyl compounds such as N-vinylformamide;

[0177] (Meth)acrylamide compounds such as (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, diacetone (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, (meth)acryloylmorpholine, (meth)acrylamide, etc.;

[0178] 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, Dicyclopentyl (meth)acrylate, 2-Hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl phthalate, Methoxy-polyethylene glycol (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl (meth)acrylate compounds such as 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethoxylated phenyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinic acid, nonylphenol EO adduct (meth)acrylate, phenoxy-polyethylene glycol (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, lactone-modified (meth)acrylate, octadecyl (meth)acrylate, isopentyl (meth)acrylate, isomyristyl (meth)acrylate, isoctadecyl (meth)acrylate, and cyclotrimethylolpropane formal (meth)acrylate;

[0179] Methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, n-octadecyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, cyclohexyl methyl vinyl ether, 4-methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenyloxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether , methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloroethoxyethyl vinyl ether, phenethyl vinyl ether, phenoxypolyethylene glycol vinyl ether, cyclohexanedimethanol monovinyl ether, isopropenyl ether-O-propylene carbonate and other monovinyl ether compounds;

[0180] Etc. In addition, E0 represents ethylene oxide.

[0181] The content of the monofunctional monomer is preferably 0.1 to 30% by mass, more preferably 1 to 10% by mass, based on the total mass of the solid content of the photosensitive resin layer, because the effects of the present invention and the like are more excellent.

[0182] (Bifunctional monomer)

[0183] The bifunctional monomer is preferably a compound having two ethylenically unsaturated groups because the effects of the present invention are more excellent. Specific examples of the ethylenically unsaturated group are as described above.

[0184] Examples of the compound having two ethylenically unsaturated groups include:

[0185] Ethylene 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;

[0186] 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;

[0187] Bisphenol A di(meth)acrylate compounds such as bisphenol A diglycidyl ether (meth)acrylate adduct, modified bisphenol A di(meth)acrylate, bisphenol A PO adduct di(meth)acrylate, and bisphenol A EO adduct di(meth)acrylate;

[0188] Etc. In addition, PO represents propylene oxide, and EO represents ethylene oxide.

[0189] The content of the bifunctional monomer is preferably 0.1 to 30% by mass based on the total mass of the solid content of the photosensitive resin layer because the effects of the present invention and the like are more excellent.

[0190] <Polymerization Inhibitor>

[0191] The photosensitive resin layer preferably contains a polymerization inhibitor (stabilizer) because the effects of the present invention and the like are more excellent.

[0192] Examples of the polymerization inhibitor include phenols, hydroquinones, and catechols.

[0193] The content of the polymerization inhibitor is preferably 0.01 to 5% by mass, more preferably 0.01 to 0.5% by mass, based on the total mass of the solid content of the photosensitive resin layer, because the flexographic printing plate precursor has better dispersibility of development residue after storage for a period of time.

[0194] <Telechelic polymer>

[0195] The photosensitive resin layer preferably contains a telechelic polymer because the effects of the present invention and the like are more excellent.

[0196] In the present specification, a "telechelic polymer" refers to a polymer having reactive functional groups at both ends.

[0197] (Main chain)

[0198] The polymer constituting the main chain of the telechelic polymer is not particularly limited, and examples thereof include thermoplastic polymers.

[0199] The above-mentioned thermoplastic polymer is not particularly limited as long as it is a thermoplastic polymer. 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.

[0200] Among these, rubber and thermoplastic elastomer are preferred, rubber is more preferred, and diene rubber is further preferred because a softer and more flexible film can be easily formed.

[0201] Specific examples of the rubber include butadiene rubber (BR), nitrile rubber (NBR), acrylic rubber, epichlorohydrin rubber, polyurethane rubber, isoprene rubber, styrene isoprene rubber, styrene butadiene rubber (SBR), ethylene-propylene copolymers, and chlorinated polyethylene. 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, and butadiene rubber and styrene butadiene rubber are more preferred, from the perspective of improved water developability and drying properties and image reproducibility.

[0202] Examples of the thermoplastic elastomer include PB (polybutadiene-based thermoplastic elastomer), polyisoprene-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, and acrylic-based thermoplastic elastomer. Specifically, 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 rubber), ACS (acrylonitrile chlorinated polyethylene styrene copolymer), acrylonitrile styrene copolymer, syndiotactic 1,2-polybutadiene, polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate, and the like. Among these, PB, SBS, and SIS are particularly preferred because of their improved water-developable properties and from the perspectives of drying properties and image reproducibility.

[0203] (End)

[0204] Telechelic polymers have reactive functional groups at both ends.

[0205] The reactive functional group is not particularly limited, but is preferably an ethylenically unsaturated group because the effects of the present invention and the like are more excellent.

[0206] The above-mentioned ethylenically unsaturated group is preferably a vinyl group (CH 2 =CH-), allyl (CH 2 =CH-CH 2 -), (meth)acryloyl or (meth)acryloyl, more preferably (meth)acryloyloxy.

[0207] The telechelic polymer may have reactive functional groups at both ends of the polymer constituting the main chain via a divalent linking group.

[0208] The divalent linking group is not particularly limited, but 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-, -SO- 2 -, -NRL-, -CO-, -NH-, -COO-, -CONRL-, -O-CO-O-, -SO 3 -、-NHCOO-、-SO 2 NRL-, -NH-CO-NH-, or a combination of two or more of these (e.g., alkyleneoxy, alkyleneoxycarbonyl, alkylenecarbonyloxy, etc.), etc. Here, RL represents a hydrogen atom or an alkyl group (preferably having 1 to 10 carbon atoms).

[0209] (Molecular weight)

[0210] From the perspective of more excellent effects of the present invention, the weight average molecular weight (Mw) of the telechelic polymer is preferably 6,000 or more, more preferably 7,000 or more, further preferably 8,000 or more, and particularly preferably 9,000 or more. The upper limit of the Mw of the telechelic polymer is not particularly limited, but from the perspective of more excellent effects of the present invention, it is preferably 500,000 or less, and more preferably 100,000 or less.

[0211] Here, the weight average molecular weight is measured by gel permeation chromatography (GPC) and calculated using standard polystyrene. Specifically, for example, HLC-8220GPC (manufactured by TOSOH CORPORATION) is used for GPC, and three TSKgeL Super HZM-H, TSKgeL Super HZ4000, and TSKgeL Super HZ2000 (manufactured by TOSOH CORPORATION, 4.6 mmID×15 cm) are used as chromatographic columns, and THF (tetrahydrofuran) is used as an eluent. And, as conditions, the sample concentration is set to 0.35% by mass, the flow rate is set to 0.35 mL / min, the sample injection amount is set to 10 μL, the measurement temperature is set to 40°C, and an IR detector is used. The calibration curve was prepared using eight samples of “TSK standard, polystyrene” manufactured by TOSOH CORPORATION: “F-40”, “F-20”, “F-4”, “F-1”, “A-5000”, “A-2500”, “A-1000”, and “n-propylbenzene”.

[0212] (HSP value)

[0213] 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 because the effects of the present invention are more excellent.

[0214] (content)

[0215] From the perspective of achieving more excellent effects of the present invention, the content of the telechelic polymer is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, further preferably 7 to 30% by mass, and particularly preferably 10 to 20% by mass, based on the total mass of the solid content of the photosensitive resin layer.

[0216] <Plasticizer>

[0217] The photosensitive resin layer preferably contains a plasticizer in order to further improve flexibility.

[0218] Specific examples of the plasticizer include liquid rubber, oil, polyester, and phosphoric acid compounds.

[0219] Specific examples of the liquid rubber include liquid polybutadiene, liquid polyisoprene, and rubbers obtained by modifying these with maleic acid or an epoxy group.

[0220] Specific examples of the oil include paraffin, cycloparaffin, and aromatic oil.

[0221] Specific examples of the polyester include adipic acid-based polyesters.

[0222] Specific examples of the phosphoric acid-based compound include phosphoric acid esters and the like.

[0223] The content of the plasticizer is preferably 0.1 to 40% by mass, more preferably 5 to 30% by mass, based on the total mass of the solid content of the photosensitive resin layer, in order to further improve the flexibility.

[0224] <Surfactant>

[0225] From the viewpoint of further improving water developability, the photosensitive resin layer preferably contains a surfactant.

[0226] Examples of the surfactant include cationic surfactants, anionic surfactants, and nonionic surfactants. Among them, anionic surfactants are preferred because they provide more excellent effects of the present invention.

[0227] Specific examples of the anionic surfactant include:

[0228] Aliphatic carboxylates such as sodium laurate and sodium oleate;

[0229] Sodium lauryl sulfate, sodium hexadecyl sulfate, sodium oleyl sulfate and other higher alcohol sulfates;

[0230] Polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate;

[0231] Polyoxyethylene alkyl allyl ether sulfates such as polyoxyethylene octyl phenyl ether sodium sulfate and polyoxyethylene nonyl phenyl ether sodium sulfate;

[0232] Alkyl sulfonates such as alkyl diphenyl ether disulfonate, sodium dodecyl sulfonate, sodium dialkyl sulfosuccinate;

[0233] Alkyl allyl sulfonates such as alkyl disulfonates, sodium dodecylbenzene sulfonate, sodium dibutylnaphthalene sulfonate, sodium triisopropylnaphthalene sulfonate;

[0234] Disodium lauryl phosphate monoester, sodium lauryl phosphate diester and other higher alcohol phosphate salts;

[0235] Polyoxyethylene alkyl ether phosphate salts such as disodium lauryl polyoxyethylene ether phosphate monoester and sodium lauryl polyoxyethylene ether phosphate diester;

[0236] Etc. These may be used alone or in combination of two or more.

[0237] Among these, sulfonic acid surfactants such as alkylsulfonates and alkylarylsulfonates are preferred because water developability is further improved.

[0238] 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 resin layer, from the viewpoint of developability or drying properties after development.

[0239] <Other additives>

[0240] The photosensitive resin layer may further contain additives such as ultraviolet absorbers, dyes, pigments, defoamers, and fragrances as appropriate for the purpose of improving various properties, within a range that does not inhibit the effects of the present invention.

[0241] <Method for producing photosensitive resin layer>

[0242] The method for producing the photosensitive resin layer is not particularly limited, and examples thereof include a method of preparing a resin composition containing the above-mentioned components and applying the resin composition to the above-mentioned support.

[0243] The film thickness of the photosensitive resin layer is preferably 0.01 to 10 mm, more preferably 0.2 to 6 mm.

[0244] 〔Infrared ablation layer〕

[0245] The infrared ablative layer included in the flexographic printing plate precursor of the present invention is a portion that serves as a mask covering the surface of the photosensitive resin layer.

[0246] The infrared ablation layer is a portion that can be removed by infrared laser, and the portion that is not removed shields (absorbs) ultraviolet light so that the ultraviolet light does not irradiate the photosensitive resin layer thereunder.

[0247] Such an infrared ablation layer can be formed using a resin composition containing a binder polymer and an infrared absorbing substance.

[0248] <Binder Polymer>

[0249] Examples of the binder polymer contained in the resin composition include polymer components corresponding to the rubber component and the resin component.

[0250] (Rubber component)

[0251] The rubber component is not particularly limited as long as it does not inhibit adhesion with the photosensitive resin layer.

[0252] Specific examples of the rubber include butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), acrylic rubber, epichlorohydrin rubber, polyurethane 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.

[0253] (Resin component)

[0254] The resin component is not particularly limited as long as it is a resin that does not inhibit adhesion with the photosensitive resin layer.

[0255] Specific examples of the resin include (meth)acrylic resins, polystyrene resins, polyester resins, polyamide resins, polysulfone resins, polyethersulfone resins, polyimide resins, acrylic resins, acetal resins, epoxy resins, and polycarbonate resins. These may be used alone or in combination of two or more.

[0256] In addition, "(meth)acrylic acid" is a symbol indicating acrylic acid or methacrylic acid, and "(meth)acryloyl" described later is a symbol indicating acryloyl or methacryloyl.

[0257] Among these, as the polymer component corresponding to the rubber component, butadiene rubber (BR), acrylonitrile butadiene rubber (NBR) or styrene butadiene rubber (SBR) is preferred, and acrylonitrile butadiene rubber (NBR) is more preferred.

[0258] Furthermore, as the polymer component corresponding to the resin component, an acrylic resin or a methacrylic resin is preferable.

[0259] <Infrared absorbing substances>

[0260] The infrared absorbing substance contained in the resin composition is not particularly limited as long as it absorbs infrared rays and converts them into heat.

[0261] 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 pigments, naphthoquinone pigments, polymethine dyes, diimmonium salts, azoimmonium pigments, chalcogen pigments, graphite carbon, iron powder, diamine metal complexes, dithiol metal complexes, phenolthiol metal complexes, mercaptophenol metal complexes, arylaluminum metal salts, inorganic compounds containing crystalline water, copper sulfate, metal oxides (e.g., cobalt oxide, tungsten oxide, etc.), and metal powders (e.g., bismuth, tin, tellurium, aluminum, etc.).

[0262] Among them, carbon black, graphite carbon, and the like are preferred from the viewpoint of having an ultraviolet absorbing function and the like.

[0263] The infrared ablative layer may contain various additives in addition to the above-mentioned binder polymer and infrared absorbing substance.

[0264] Examples of such additives include surfactants, plasticizers, ultraviolet absorbing substances, mold release agents, dyes, pigments, defoaming agents, and fragrances.

[0265] The method for producing the infrared ablation layer is not particularly limited, and examples thereof include a method of preparing a resin composition containing the above-mentioned components and applying the resin composition to a photosensitive resin layer.

[0266] The film thickness of the infrared ablation layer is preferably 0.1 to 6 μm, more preferably 0.5 to 3 μm.

[0267] 〔Coating sheet〕

[0268] like Figure 1 As shown, the flexographic printing plate precursor of the present invention may have a cover sheet.

[0269] Such a covering 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.

[0270] 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.

[0271] Examples of the material for the polymer film include cellulose polymers; acrylic polymers having acrylate polymers such as polymethyl methacrylate and lactone ring-containing polymers; thermoplastic norbornene polymers; polycarbonate polymers; polyester polymers such as polyethylene terephthalate, polyethylene naphthalate, and fluoropolyester polymers; styrene polymers such as polystyrene and acrylonitrile-styrene copolymer (AS resin); polyolefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, and polybutadiene; vinyl chloride polymers; amide polymers such as nylon and aromatic polyamide; imide polymers; sulfone polymers; polyethersulfone polymers; polyetheretherketone polymers; polyphenylene sulfide polymers; vinylidene chloride polymers; vinyl alcohol polymers; vinyl butyral polymers; aromatic ester polymers; polyoxymethylene polymers; epoxy polymers; or polymers obtained by mixing these polymers.

[0272] Furthermore, a release treatment may be applied to the surface of the covering sheet (the surface on which the infrared ablation layer is formed) to suppress adhesion of the infrared ablation layer and improve the releasability of the covering sheet. As such a release treatment, a method of coating a release agent on the surface of the covering sheet to form a release layer may be cited. As the release agent, a silicone-based release agent, an alkyl-based release agent, etc. may be cited.

[0273] The film thickness of the covering sheet is preferably 25 to 250 μm.

[0274] [Method for producing flexographic printing plate]

[0275] The method for manufacturing a flexographic printing plate of the present invention is a method for manufacturing a flexographic printing plate having a non-image area and an image area, and the method for manufacturing a flexographic printing plate comprises:

[0276] 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;

[0277] An exposure step, after the mask forming step, exposing the photosensitive resin layer of the flexographic printing plate precursor of the present invention to an image through the mask;

[0278] In the development step, after the exposure step, development is performed using a developer to form a non-image area and an image area.

[0279] [Mask formation process]

[0280] The mask forming step is a step of forming an image on the infrared ablation layer and forming a mask used in the exposure step described later.

[0281] Here, when the infrared ablation layer is irradiated with infrared laser light, heat is generated by the infrared absorbing material, and the infrared ablation layer is removed, ie, laser ablated, by the heat.

[0282] Therefore, by selectively laser ablating the infrared ablation layer according to the image data, it is possible to obtain an image mask capable of forming a latent image on the photosensitive resin layer.

[0283] When irradiating with infrared laser light, infrared laser light having an oscillation wavelength in the range of 750 nm to 3000 nm is used.

[0284] Examples of such lasers include solid lasers such as ruby ​​laser, alexandrite laser, perovskite laser, Nd-YAG laser, and emerald glass laser; semiconductor lasers such as InGaAsP, InGaAs, and GaAsAl; and pigment lasers such as rhodamine pigment.

[0285] Furthermore, fiber lasers obtained by amplifying these light sources with optical fibers can also be used.

[0286] Among these, it is preferable to use an exposure light source having an oscillation wavelength of 900 to 1200 nm, and it is more preferable to use a fiber laser, because the sensitivity of the infrared ablation layer becomes higher.

[0287] [Exposure process]

[0288] The exposure process is a process of exposing the photosensitive resin layer in an image-like manner through the mask obtained in the mask forming process. By irradiating the photosensitive resin layer with ultraviolet rays in an image-like manner, crosslinking and / or polymerization of the area irradiated with ultraviolet rays can be caused, thereby curing it.

[0289] 〔Development process〕

[0290] The development step is a step of developing with a developer to form a non-image area and an image area.

[0291] The developer used in the above-mentioned development step is not particularly limited, and any conventionally known developer can be used, but from the viewpoint of reducing environmental burden, it is preferred to use a developer containing 50% by mass or more of water (hereinafter, also referred to as "aqueous developer"). In addition, the developer may be an aqueous solution or a suspension (e.g., an aqueous dispersion, etc.).

[0292] Furthermore, the content of water contained 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.

[0293] 〔Rinsing process〕

[0294] The method for producing a flexographic printing plate of the present invention preferably includes a rinsing step of rinsing the surfaces of the non-image area and the image area formed in the developing step with water after the developing step.

[0295] The rinsing method in the above-mentioned rinsing step includes a method of washing with tap water, a method of spraying high-pressure water with a sprayer, a method of using a known intermittent or conveying brush-type washing machine as a developer for a flexographic printing plate and mainly brushing the surface of the non-image part and the image part in the presence of water, etc.

[0296] Example

[0297] Below, cite embodiment and the present invention is further described in detail.The material, usage amount, ratio, processing content and processing sequence etc. shown in the following embodiment can be appropriately changed as long as it does not depart from the purpose of the present invention.Therefore, the scope of the present invention should not be interpreted restrictively by the embodiment shown below.

[0298] [Example 1]

[0299] [Adjustment of mask layer]

[0300] To 100 parts by mass of a binder polymer composed of 50 parts by mass of acrylic resin A (HYPER-LU M5000, Tg: 65°C, manufactured by Negami Chemical Industrial Co., Ltd.) and 50 parts by mass of NBR, 100 parts by mass of carbon black and 3 parts by mass of a plasticizer were added, and 812 parts by mass of methyl isobutyl ketone as a solvent was further added and mixed by stirring with a blade.

[0301] Next, the obtained mixed liquid was dispersed using a three-roll mill, and methyl isobutyl ketone was further added so that the solid content became 15% by mass, thereby preparing a composition for forming an infrared ablation layer.

[0302] [Adjustment of photosensitive resin layer]

[0303] A water-dispersible latex (Nipol LX111NF, a water-dispersible latex of polybutadiene, solid content 55%, manufactured by Zeon Corporation, 59.6 parts by mass), a telechelic polymer (BAC-45, manufactured by OSAKA ORGANIC CHEMICAL INDUSTRY LTD.) (polybutadiene having acryloyloxy groups at both ends, Mw=10,000) 10 parts by mass and 1,9-nonanediol dimethacrylate (NK ester NOD-N, manufactured by SHIN-NAKAMURA CHEMICAL CO, LTD.) 9 parts by mass 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.

[0304] The mixture, 20 parts by mass of butadiene rubber (NF35R, manufactured by Asahi Kasei Corporation), 15 parts by mass of a plasticizer (diana process oil PW-32, manufactured by Idemitsu Kosan Co., Ltd.) and 5 parts by mass of a surfactant (RAPISOL A-90, effective weight 90%, manufactured by NOF CORPORATION) were kneaded in a kneader set at 110° C. for 45 minutes.

[0305] Then, 0.2 parts by mass of a thermal inhibitor, 3 parts by mass of a compound represented by the above formula (1-4) (Omnirad 127, manufactured by IGM Resins BV) and 2 parts by mass of a compound represented by the above formula (2-1) (Omnirad 369E, manufactured by IGM Resins BV) were added to a kneader and kneaded for 5 minutes to prepare a composition for a photosensitive resin layer.

[0306] 〔Production of flexographic printing plate master〕

[0307] The above-mentioned infrared ablation layer forming composition was applied to a PET film (cover sheet) with a thickness of 125 μm coated with a silicone-based release agent using a rod coater in such a manner that the thickness of the coating film after drying becomes 1 μm, and the film was dried at 120° C. for 5 minutes, thereby obtaining a laminate X consisting of an infrared ablation layer / cover sheet.

[0308] Next, the composition for the photosensitive resin layer was sandwiched between the laminate X and the surface of the support body coated with an adhesive on the surface of a PET film (substrate) with a thickness of 125 μm, and the laminate was pressed using a press heated to 120° C. in such a way that the thickness of the photosensitive resin layer became 1.5 mm, thereby producing the flexographic printing plate original of Example 1 in which the support body, the photosensitive resin layer, the infrared ablation layer and the covering sheet were laminated in this order.

[0309] 〔Production of flexographic printing plates〕

[0310] From the obtained flexographic printing plate precursor, a printing plate was produced using the following apparatus.

[0311] Specifically, the obtained flexographic printing plate precursor was exposed from the back side at an energy of 80 W for 18 seconds using the following ultraviolet exposure machine, thereby subjecting the flexographic printing plate precursor to back side exposure.

[0312] Next, using the following imaging machine, imaging was performed by ablating the infrared ablation layer, and main exposure was performed by exposing from the front surface (the back side of the back side) at 80 W for 420 seconds.

[0313] Next, development was performed for 12 minutes using the following cleaning machine and cleaning solution.

[0314] Next, the film was dried using hot air at 60° C. until moisture was removed.

[0315] Next, exposure (post-exposure) was performed for 720 seconds from the photosensitive resin layer side using the following ultraviolet exposure device to prepare a flexographic printing plate.

[0316] <Imaging Machine>

[0317] CDI Spark 4835 Inline (manufactured by Esko-Graphics BV.)

[0318] <Exposure machine>

[0319] UV exposure machine Concept 302ECDLF (product name) (manufactured by Glunz & Jensen)

[0320] <Cleaning Machine>

[0321] ·C-Touch2530 Water Wash Plate Processor (manufactured by GS Trading)

[0322] <Cleaning fluid>

[0323] · Aqueous solution of Finish Power & Pure Powder SP (manufactured by Reckitt Benckiser Group plc) (concentration: 0.5% by mass)

[0324] [Examples 2 to 6 and Comparative Examples 1 to 7]

[0325] A flexographic printing plate precursor was prepared in the same procedure as in Example 1, except that the developing method or the types and contents of the photopolymerization initiator represented by formula (1) and the photopolymerization initiator represented by formula (2) were changed as shown in Table 1 below, and the photopolymerization initiator represented by formula (3) was blended as shown in Table 1 below.

[0326] In the development method (solvent development) of Example 2, the same procedure as in Example 1 was followed except that POLYMER FLEXO A2 / S (manufactured by AGI Graphics) was used as the cleaning machine and FLEXOSOL-i (manufactured by Du Pont) was used as the cleaning liquid.

[0327] [evaluate]

[0328] 〔Microunit reproducibility〕

[0329] The microcell (MC) reproducibility of the obtained flexographic printing plate was evaluated by the following method.

[0330] First, a laser confocal microscope OPTELICS (registered trademark) HYBRID (manufactured by Lasertec Corporation) was used, and a 50x Apo (high aperture number (high NA)) objective lens was used to confocally measure the surface of the solid image portion of the flexographic printing plate at a height of 0.1 μm, thereby obtaining three-dimensional data. In addition, an area of ​​300 μm in length and 300 μm in width was used as the evaluation range.

[0331] From the observation image based on the three-dimensional data, 100 or more convex parts are observed, and the number of convex parts that are reproduced without loss is obtained.

[0332] Next, the image reproduction % is calculated by the following formula.

[0333] Image reproduction % = (number of convex parts reproduced without loss) / (number of evaluations) × 100

[0334] Evaluation was performed based on the following criteria. The results are shown in Table 1 below.

[0335] In order to obtain a printed matter having a higher solid density, the image reproduction of the micro unit is preferably 3 to 5, more preferably 4 to 5, and further preferably 5. When the image reproduction is less than 80%, the unevenness of the ink transferred to the printed matter is large, and the solid density deteriorates.

[0336] <Evaluation Criteria>

[0337] 5: Image reproduction is more than 98%

[0338] 4: Image reproduction is 95% or more and less than 98%

[0339] 3: Image reproduction is 90% or more and less than 95%

[0340] 2: Image reproduction is 80% or more and less than 90%

[0341] 1: Image reproduction is less than 80%

[0342] [Durability of independent dots]

[0343] The obtained flexographic printing plate was rubbed four times on the image portion using a continuous load type scratch resistance tester (HEIDON TYPE: 18) under the conditions of a load of 500 g and a reciprocating speed of 100 mm / min, using a cotton cloth as a rubbing member. The 10 independent small dots with a diameter of 500 μm determined before the rubbing test were evaluated for whether the independent small dots were missing or folded after the rubbing test according to the following criteria.

[0344] From the viewpoint of printing durability and workability, in practical use, 3 to 5 are preferable, 4 to 5 are more preferable, and 5 is still more preferable.

[0345] <Evaluation Criteria>

[0346] 5: None of the 10 independent dots are missing or folded

[0347] 4: 1 out of 10 independent spots is missing or folded

[0348] 3: 2 out of 10 independent spots are missing or folded

[0349] 2: 3 or 4 of 10 independent spots are missing or folded

[0350] 1: More than 5 of 10 independent spots are missing or folded

[0351] [Table 1]

[0352]

[0353] In the above Table 1, the structures of the photopolymerization initiators are described below.

[0354] Omnirad 127

[0355] [Chemical formula 7]

[0356]

[0357] [Chemical formula 8]

[0358]

[0359] [Chemical formula 9]

[0360]

[0361] [Chemical formula 10]

[0362]

[0363] [Chemical formula 11]

[0364]

[0365] The results shown in Table 1 show that when the photopolymerization initiator represented by the formula (2) is not added, the durability of the independent dots is poor regardless of the presence or absence of the photopolymerization initiator represented by the formula (3) (Comparative Examples 1 to 3).

[0366] Furthermore, it was found that when the photopolymerization initiator represented by the above formula (1) was not blended, the reproducibility of the microunit was poor regardless of the presence or absence of the photopolymerization initiator represented by the formula (3) (Comparative Examples 4 to 6).

[0367] Furthermore, it was found that when only the photopolymerization initiator represented by the formula (3) was blended, the durability of the independent dots was poor (Comparative Example 7).

[0368] On the other hand, when the photopolymerization initiator represented by the above formula (1) and the photopolymerization initiator represented by the above formula (2) are blended, the reproducibility of the microunit becomes good and the durability of the independent small dots also becomes good (Examples 1 to 6).

[0369] Here, from the results of Example 1, Comparative Example 2, and Comparative Example 5, it is understood that the effect exerted by the combined use of the photopolymerization initiator represented by the above formula (1) and the photopolymerization initiator represented by the above formula (2) is a synergistic effect.

[0370] Furthermore, from the comparison of Examples 1 to 3, it is understood that when the photopolymerization initiator represented by the formula (3) is further blended, the reproducibility of the microunit and the durability of the independent dots are further improved.

[0371] Furthermore, from the comparison between Example 1 and Example 6, it can be seen that if the content of the photopolymerization initiator represented by the above formula (2) is less than 50% by mass relative to the total mass of the photopolymerization initiator represented by the above formula (1) and the photopolymerization initiator represented by the above formula (2), the balance between the reproducibility of the microunits and the durability of the independent dots becomes good.

[0372] Explanation of symbols

[0373] 1-support, 2-photosensitive resin layer, 3-infrared ablation layer, 4-covering sheet, 10-flexographic printing plate precursor.

Claims

1. A flexographic printing plate precursor, which comprises a support, a photosensitive resin layer and an infrared ablation layer in this order, The photosensitive resin layer contains a photopolymerization initiator represented by the following formula (1) and a photopolymerization initiator represented by the following formula (2). In the formula (1), n represents 1 or 2, X 1 and X 2 Each independently represents a hydrogen atom or -OR 1 Substituents other than the group represented by 1 represents a hydrogen atom or a substituent, wherein, X 1 and X 2 Optionally linked to each other to form a ring, when n is 2, multiple X 1 Optionally, each of the same or different, multiple X 2 are optionally the same or different, When n is 1, X 3 represents a hydrogen atom or a substituent. When n is 2, X 3 represents a single bond or a divalent linking group, In the formula (2), Y 1 and Y 2 Each independently represents a hydrogen atom or -OR 1 Substituents other than the group represented by 1 represents a hydrogen atom or a substituent, wherein Y 1 and Y 2 are optionally linked to each other to form a ring, Y 3 represents a hydrogen atom or a substituent, Y 4 and Y 5 Each independently represents a hydrogen atom or a substituent, wherein Y 4 and Y 5 They are optionally linked to each other to form a ring.

2. The flexographic printing plate precursor according to claim 1, wherein The photosensitive resin layer further contains a photopolymerization initiator represented by the following formula (3): In the formula (3), Z 1 , Z 2 and Z 3 each independently represents a hydrogen atom or a substituent, Z 4 represents a substituent.

3. The flexographic printing plate precursor according to claim 1, wherein The photosensitive resin layer contains water-dispersible particles.

4. A method for manufacturing a flexographic printing plate, the flexographic printing plate having a non-image portion and an image portion, the method for manufacturing a flexographic printing plate comprising: A mask forming step of forming a mask by forming an image on the infrared ablation layer of the flexographic printing plate precursor according to any one of claims 1 to 3; an exposure step of exposing the photosensitive resin layer of the flexographic printing plate precursor in an image shape through the mask after the mask forming step; and The developing step is to perform development using a developer after the exposure step to form a non-image area and an image area.

Images