Method of manufacturing a printing plate and printing method

Abstract

A method for manufacturing a printing plate having an exposure process for forming relief by exposure to a photosensitive resin composition, and a developing process for developing the photosensitive resin composition of the unexposed portion in the exposure process by attaching or adsorbing it to a developing medium, wherein, at the developing temperature of the developing process, the storage modulus of the photosensitive resin composition of the unexposed portion is 100 Pa or more and 4000 Pa or less, and the developing medium is a wiper having an elastic recovery rate of 30% or more and 99% or less.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a printing plate and a printing method. Background Technology

[0002] Recently, flexographic printing has become widely used as a method for printing on soft packaging materials such as paper or film. Examples of printing plates for relief printing, which are representative of flexographic printing, include photosensitive resin plates.

[0003] As a method for manufacturing a flexographic printing plate using a photosensitive resin plate, the following methods may be cited.

[0004] First, ultraviolet exposure (called back exposure) is performed on a photosensitive resin composition layer through a support to form a uniform photocured layer. Subsequently, relief exposure is performed on the back side, that is, the side opposite to the side exposed to ultraviolet light, on the side of the photosensitive resin composition layer in an uncured state, to obtain a flexographic printing plate. Examples of the above relief exposure method include performing ultraviolet exposure through a transparent image carrier, such as a negative film that selectively transmits ultraviolet light, or performing ultraviolet exposure through a thin layer that forms an ultraviolet-transmitting portion by ablating an image of digital information with an infrared laser. Then, a relief image is formed by washing away the photosensitive resin composition in the unexposed portion of the flexographic printing plate with a developer, thereby obtaining a flexographic printing plate.

[0005] Meanwhile, with the recent rise in environmental awareness, dry development processes that do not use developer are being considered.

[0006] Among them, a thermal development method in which the flexographic printing plate is heated after relief exposure to melt the unexposed areas and the molten unexposed areas are removed by a developing medium such as a nonwoven fabric is attracting attention because it is possible to develop without using solvents.

[0007] A development method using a thermal development method has been proposed as a dry development process that does not use the above-mentioned developer (see, for example, Patent Document 1). This development method has the advantage of not generating organic solvent waste or contaminated wastewater by-products, as is the case with conventional development methods using a developer. In addition, it has the advantage of not requiring a long drying process after development.

[0008] On the other hand, the above-mentioned thermal development method has the problem that, since it does not dissolve or disperse the uncured resin in the solvent, it has poor developability compared to conventional development methods using a developer solution, and tends to leave residue. Therefore, in the above-mentioned thermal development method, in order to improve developability, it is necessary to press the developing medium, such as a non-woven fabric, against the flexographic printing plate strongly or repeatedly, and in this process, the plate thickness tends to become thin. Furthermore, as the size of the flexographic printing plate increases, it becomes difficult to press the developing medium with uniform pressure across the entire plate, making it easy for the thickness uniformity of the final flexographic printing plate to be compromised. Consequently, it has the problem that adverse effects, such as poor image uniformity during printing, are likely to occur. In particular, maintaining thickness uniformity has become a technical challenge for large-sized flexographic printing plates, for which demand has recently been increasing.

[0009] Considering the problems of thermal development methods regarding image uniformity during printing as described above, a technology has been proposed to improve image uniformity during printing using a flexographic printing plate by controlling the surface roughness of the flexographic printing plate during thermal development (see, for example, Patent Document 2). Prior art literature

[0010] Patent Document 1: Japanese Patent Publication No. 3117749 Patent Document 2: Japanese Patent Publication No. 5827746 The problem to be solved

[0011] However, according to the technology proposed in Patent Document 2, while the surface roughness of the flexographic printing plate is controlled, there is a problem that there is still room for improvement regarding the thickness uniformity of the flexographic printing plate.

[0012] Therefore, the present invention aims to provide a method for manufacturing a printing plate with excellent thickness uniformity when using a dry development process, taking into account the problems of the aforementioned prior art. means of solving the problem

[0013] As a result of repeated careful consideration to solve the above problem, the inventors discovered that the problem of the aforementioned prior art can be solved by combining a developing medium having specific physical properties and a photosensitive resin composition in a dry developing process, and thus completed the present invention.

[0014] That is, the present invention is as follows.

[0015] [1]

[0016] An exposure process for forming relief by exposure to a photosensitive resin composition, and

[0017] A method for manufacturing a printing plate having a developing process in which a photosensitive resin composition of an unexposed portion in the above-mentioned exposure process is attached to or adsorbed onto a developing medium to develop,

[0018] At the development temperature of the above development process, the storage modulus of the photosensitive resin composition of the unexposed portion is 100 Pa or more and 4000 Pa or less, and

[0019] A method for manufacturing a printing plate, wherein the above-mentioned developing medium is a wiper having an elastic recovery rate of 30% or more and 99% or less.

[0020] [2]

[0021] A method for manufacturing a printing plate as described in [1], wherein the storage modulus of the photosensitive resin composition of the unexposed portion at the above development temperature is 100 Pa or more and 350 Pa or less.

[0022] [3]

[0023] A method for manufacturing a printing plate as described in [1], wherein the storage modulus of the photosensitive resin composition of the unexposed portion is 100 Pa or more and 250 Pa or less at the above development temperature.

[0024] [4]

[0025] A method for manufacturing a printing plate as described in any one of [1] to [3], wherein the loss elastic modulus of the photosensitive resin composition of the unexposed portion at the above development temperature is 90 Pa or more and 500 Pa or less.

[0026] [5]

[0027] A method for manufacturing a printing plate as described in any one of [1] to [4], wherein the above-mentioned developing medium is a wiper having an elastic recovery rate of 35% or more and 99% or less.

[0028] [6]

[0029] A method for manufacturing a printing plate as described in any one of [1] to [5], wherein the above-mentioned developing medium is a wiper having an elastic recovery rate of 40% or more and 99% or less.

[0030] [7]

[0031] A method for manufacturing a printing plate as described in any one of [1] to [6], wherein the above-mentioned developing medium is a wiper having an elastic recovery rate of 60% or more and 99% or less.

[0032] [8]

[0033] A method for manufacturing a printing plate according to any one of [1] to [7], wherein the relief depth of the printing plate is 0.1 mm or more and 10.0 mm or less.

[0034] [9]

[0035] A method for manufacturing a printing plate as described in any one of [1] to [8], wherein the wiper is a non-woven fabric.

[0036]

[10]

[0037] A method for manufacturing a printing plate according to any one of [1] to [9], having a process for recovering the photosensitive resin composition of the unexposed portion attached to or adsorbed on the above-mentioned developing medium as a photosensitive resin composition in the manufacture of a new printing plate.

[0038]

[11]

[0039] A method for manufacturing a printing plate according to any one of [1] to

[10] , wherein the photosensitive resin composition of the unexposed portion attached to or adsorbed on the above-mentioned developing medium is recovered and used as a photosensitive resin composition in the manufacture of a new printing plate.

[0040]

[12]

[0041] A printing method having a process for manufacturing a printing plate using the method for manufacturing a printing plate described in any one of [1] to

[11] above, and a printing process for printing using the manufactured printing plate. Effects of the invention

[0042] According to the present invention, when a dry development process is used, a printing plate with excellent thickness uniformity can be obtained. Specific details for implementing the invention

[0043] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiments") will be described in detail; however, the following embodiments are examples for explaining the present invention and are not intended to limit the present invention to the following contents.

[0044] The present invention may be implemented with appropriate modifications within the scope of not departing from its gist.

[0045] [Method of manufacturing printing plates]

[0046] The method for manufacturing a printing plate of the present embodiment is,

[0047] An exposure process for forming relief by exposure to a photosensitive resin composition, and

[0048] The above-mentioned exposure process has a developing process in which a photosensitive resin composition of an unexposed portion is attached to or adsorbed onto a developing medium to develop.

[0049] At the development temperature of the above development process, the storage modulus of the photosensitive resin composition of the above-mentioned unexposed portion is 100 or more and 4000 Pa or less, and the developing medium is a wiper having an elastic recovery rate of 30% or more and 99% or less.

[0050] The printing plate obtained by the manufacturing method of the present embodiment is preferably a flexographic printing plate (iron plate printing plate).

[0051] In the method for manufacturing a printing plate according to the present embodiment, the unexposed portion of the photosensitive resin composition of the printing plate after the exposure process is removed using a developing medium.

[0052] The above unexposed portion is removed by being attached or adsorbed through contact with a wiper, which is a developing medium.

[0053] According to the method for manufacturing a printing plate of the present embodiment, a printing plate with excellent thickness uniformity can be obtained.

[0054] (Printing plate)

[0055] In the method for manufacturing a printing plate according to the present embodiment, a printing plate is obtained by forming a relief on a photosensitive resin composition layer by exposure during an exposure process, and in a developing process, the unexposed portion of the photosensitive resin composition layer is removed by attaching or adsorbing it to a developing medium.

[0056] The printing plate has a configuration comprising at least a support (a) and a photosensitive resin composition layer (b) laminated on the support (a) prior to exposure to a photosensitive resin composition layer. In this specification, such a configuration may be described as a "photosensitive resin composition for a printing plate."

[0057] That is, as described below, a printing plate can be obtained by forming a relief on a photosensitive resin composition for a printing plate by pattern exposure, and by melting and removing an unexposed portion from the printing plate.

[0058] <support(a)>

[0059] Examples of support materials (a) include, but are not limited to, polyester film, polyamide film, polyacrylonitrile film, polyvinyl chloride film, etc.

[0060] Among these, a polyester film is preferred as the support (a).

[0061] Polyesters used for the support (a) are not limited to the following, but examples include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.

[0062] The thickness of the support (a) is not particularly limited, but is preferably 50 to 300 μm.

[0063] In addition, an adhesive layer may be formed on the support (a) for the purpose of increasing the adhesion between the support (a) and the photosensitive resin composition layer (b) described later. The adhesive layer is not particularly limited, but examples include the adhesive layers described in International Publication No. 2004 / 104701, Japanese Patent No. 3094647, and Japanese Patent No. 2634429.

[0064] <Photosensitive resin composition layer (b)>

[0065] The above photosensitive resin composition for a printing plate has a photosensitive resin composition layer (b) on a support (a).

[0066] The photosensitive resin composition layer (b) may be directly laminated on the support (a), or indirectly laminated through the adhesive layer, etc.

[0067] The photosensitive resin composition layer (b) is not particularly limited, but may contain, for example, a polymer (b-1) described later, and preferably may further contain an ethylene unsaturated compound (b-2) and a photopolymerization initiator (b-3).

[0068] In addition, the photosensitive resin composition layer (b) may further contain auxiliary additive components described below as necessary.

[0069] Below, each component is explained in detail.

[0070] [Polymer(b-1)]

[0071] As for the polymer (b-1), it is not particularly limited, but, for example, a linear, branched, or tree-like polymer may be used, and it may be a homopolymer or a copolymer. The copolymer may be a random copolymer, an alternating copolymer, or a block copolymer.

[0072] Suitable polymers (b-1) include, for example, completely or partially hydrolyzed polyvinyl esters, partially hydrolyzed polyvinyl acetate, polyvinyl alcohol derivatives, partially hydrolyzed vinyl acetate / alkylene oxide graft copolymers or partially hydrolyzed vinyl acetate / alkylene oxide graft copolymers, and also polyvinyl alcohol, polyamides and mixtures thereof that are conventionally used in the manufacture of printing plates, which are further acrylated by polymer-like reactions.

[0073] In addition to the above, the polymer (b-1) may be, for example, a thermoplastic elastomer binder.

[0074] As the thermoplastic elastomer, a thermoplastic elastomer block copolymer may be used, and the thermoplastic elastomer block copolymer may comprise at least one block comprising an alkenyl aromatic monomer unit and at least one block comprising a 1,3-diene monomer unit. The alkenyl aromatic compound forming the alkenyl aromatic monomer unit may be, for example, styrene, α-methylstyrene, or vinyltoluene, and among these, it is preferable to include styrene in order to allow the photosensitive resin composition layer (b) to be molded smoothly at a relatively low temperature and to improve the thickness uniformity of the surface. As for the 1,3-diene, it is preferable to include butadiene and / or isoprene in order to reduce the steric hindrance of the vinyl group to increase photocrosslinking efficiency and to prevent a decrease in thickness uniformity due to breakage of the finally obtained printing plate.

[0075] In addition, from the perspective of suppressing the deterioration of thickness uniformity due to wear of the printing plate when printing is performed for a long time, it is preferable to include polyurethane as the polymer (b-1). Furthermore, from the perspective of improving the mechanical properties of the printing plate finally obtained by photocrosslinking and suppressing the deterioration of thickness uniformity due to breakage or wear, it is preferable that the polyurethane has (meth)acrylic groups at the terminals.

[0076] As a method for manufacturing a polyurethane having (meth)acrylic groups at the terminals, for example, a method of reacting a diol having repeating units within a molecule with a diisocyanate to form a polyurethane having isocyanate groups at the terminals at any molecular weight, and then reacting the polyurethane with a compound containing active hydrogen and (meth)acrylic groups within one molecule. In addition, a method of reacting a diol having repeating units within a molecule with a diisocyanate to form a polyurethane having isocyanate groups at the terminals at any molecular weight, and then reacting the polyurethane with a compound containing hydroxyl groups and (meth)acrylic groups within one molecule may also be cited.

[0077] The polyurethane structure obtained by the above-described manufacturing method is a structure formed by the reaction of a diol having repeating units within the molecule and a diisocyanate.

[0078] Hereinafter, the “polyurethane having (meth)acrylic groups at the terminals” synthesized by the method described above is referred to as an “unsaturated prepolymer.”

[0079] The “diol having repeating units within the molecule” used in the preparation of the above unsaturated prepolymer is not limited to the following, but examples include polyester diols containing a dicarboxylic acid and a diol, polyether diols, polyether polyester copolymer diols, and 1,2-polybutadiene compounds having terminal hydroxyl groups. One type of diol having repeating units within the molecule may be used alone, or two or more types may be used in combination.

[0080] Examples of dicarboxylic acids constituting the above polyester diol include, but are not limited to, succinic acid, glutaric acid, adipic acid, pimetic acid, souveric acid, azelaic acid, sebacic acid, maleic acid, terephthalic acid, isophthalic acid, and 1,5-naphthalenedicarboxylic acid.

[0081] Examples of diols constituting the above polyester diol include, but are not limited to, 1,4-butanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, neopentyldiol, 1,6-hexanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, and diethylene glycol (dioxyethylenediol).

[0082] The above polyether diols are not limited to the following, but examples include polyoxyethylene diol, polyoxypropylene diol, polyoxytetramethylene diol, polyoxy-1,2-butylene diol, polyoxyethylene / polyoxypropylene random copolymer diol, polyoxyethylene / polyoxypropylene block copolymer diol, polyoxyethylene / polyoxytetramethylene random copolymer diol, and polyoxyethylene / polyoxytetramethylene block copolymer diol.

[0083] The above polyether-polyester copolymer polyol is not limited to the following, but may include, for example, a copolymer having a structure in which repeating units forming the molecular chain of the above-described polyether-polyol and repeating units forming the molecular chain of the above-described polyester-polyol are linked in a block or random manner.

[0084] The above 1,2-polybutadiene compound having terminal hydroxyl groups may also be a hydrogenated compound. Examples of 1,2-polybutadiene compounds having terminal hydroxyl groups include, but are not limited to the following, hydrides of poly-1-butene or hydrides of 1,2-polybutadiene. The terminal hydroxyl groups are not particularly limited, but from the perspective of maintaining the thickness uniformity of the finally obtained flexographic printing plate, it is preferable that there are 1.2 or more and 2.0 or fewer per molecule, and more preferable that there are 1.5 or more and 2.0 or fewer.

[0085] Examples of the above diisocyanates include, but are not limited to, tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and norbornene diisocyanate.

[0086] Diisocyanates are used either alone or in combination of two or more types.

[0087] In terms of setting the storage modulus and / or loss modulus of the photosensitive resin composition layer (b) to an appropriate numerical range, the content of the polymer (b-1) in the photosensitive resin composition layer (b) is preferably 20 mass% or more, more preferably 40 mass% or more and 90 mass% or less, even more preferably 50 mass% or more and 90 mass% or less, and even more preferably 60 mass% or more and 80 mass% or less.

[0088] [Ethylene unsaturated compound (b-2)]

[0089] The photosensitive resin composition layer (b) preferably contains an ethylenically unsaturated compound (b-2) as described above. The ethylenically unsaturated compound (b-2) is a compound having unsaturated double bonds capable of radical polymerization.

[0090] Examples of ethylene unsaturated compounds (b-2) include, but are not limited to, olefins such as ethylene, propylene, vinyltoluene, styrene, and divinylbenzene; acetylenes; (meth)acrylic acid and / or its derivatives; haloolefins; unsaturated nitriles such as acrylonitrile; unsaturated amides such as acrylamide and methacrylamide and their derivatives; unsaturated dicarboxylic acids such as maleic anhydride, maleic acid, and fumaric acid and their derivatives; vinyl acetates; N-vinylpyrrolidone; N-vinylcarbazole; N-substituted maleimide compounds, etc.

[0091] Among these, (meth)acrylic acid and / or its derivatives are preferred as the ethylene unsaturated compound (b-2) in order to maintain thickness uniformity by improving UV curability or the scratch resistance of the photosensitive resin composition layer (b) after curing.

[0092] Examples of each of the above derivatives include, but are not limited to: alicyclic compounds having a cycloalkyl group, a bicycloalkyl group, a cycloalkenyl group, a bicycloalkenyl group, etc.; aromatic compounds having a benzyl group, a phenyl group, a phenoxy group, or a naphthalene backbone, an anthracene backbone, a biphenyl backbone, a phenanthrene backbone, a fluorene backbone, etc.; compounds having an alkyl group, an alkyl halide group, an alkoxyalkyl group, a hydroxyalkyl group, an aminoalkyl group, a glycidyl group, etc.; ester compounds with polyhydric alcohols such as alkylene glycol, polyoxyalkylene glycol, polyalkylene glycol, or trimethylolpropane; and compounds having a polysiloxane structure such as polydimethylsiloxane or polydiethylsiloxane.

[0093] In addition, the ethylene unsaturated compound (b-2) may be a complex aromatic compound containing elements such as nitrogen and sulfur.

[0094] Examples of the above (meth)acrylic acid and / or its derivatives include, but are not limited to, diacrylates and dimethacrylates of alkanediols such as hexanediol and nonanediol; diacrylates and dimethacrylates of glycols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol and butylene glycol; trimethylolpropane tri(meth)acrylate; dimethylol tricyclodecane di(meth)acrylate; isobornyl (meth)acrylate; phenoxypolyethylene glycol (meth)acrylate; pentaerythritol tetra(meth)acrylate, etc.

[0095] These may be used as a single type alone, or as a combination of two or more types.

[0096] In order to improve the durability of the printing plate obtained at the end and maintain thickness uniformity, it is preferable to use at least one type of (meth)acrylate as the ethylene unsaturated compound (b-2), and it is more preferable to use at least one type of dual (meth)acrylate.

[0097] The number average molecular weight (Mn) of the ethylenically unsaturated compound (b-2) is preferably 100 or more and 1500 or less, more preferably 110 or more and 1000 or less, and even more preferably 130 or more and 800 or less, in order to control the storage modulus and / or loss modulus of the photosensitive resin composition to an appropriate numerical range.

[0098] The number average molecular weight (Mn) of ethylenically unsaturated compounds can be determined by gel permeation chromatography (GPC).

[0099] The content of the ethylene unsaturated compound (b-2) in the photosensitive resin composition layer (b) is preferably 2 mass% or more and less than 60 mass%, more preferably 5 mass% or more and 50 mass% or less, and even more preferably 10 mass% or more and 40 mass% or less, in order to control the storage modulus and / or loss modulus of the photosensitive resin composition to an appropriate numerical range when the total amount of the photosensitive resin composition layer (b) is 100 mass%.

[0100] [Photopolymerization initiator (b-3)]

[0101] The photosensitive resin composition layer (b) preferably contains a photopolymerization initiator (b-3).

[0102] A photopolymerization initiator (b-3) is a compound that absorbs light energy and generates radicals, and examples include a decay-type photopolymerization initiator, a hydrogen withdrawal-type photopolymerization initiator, and a compound having a portion that functions as a hydrogen withdrawal-type photopolymerization initiator and a portion that functions as a decay-type photopolymerization initiator within the same molecule.

[0103] As a photopolymerization initiator (b-3), examples include, but are not limited to, benzophenones such as benzophenone, 4,4-bis(diethylamino)benzophenone, 3,3',4,4'-benzophenone tetracarboxylic acid anhydride, 3,3',4,4'-tetramethoxybenzophenone; anthraquinones such as t-butylanthraquinone, 2-ethylanthraquinone; thioxantones such as 2,4-diethylthioxantone, isopropylthioxantone, 2,4-dichlorothioxantone; and mihler ketone; Acetophenones such as diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, trichloroacetophenone, etc.; benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, etc.; Examples include acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; methylbenzoyl formate; 1,7-bisacridinylheptane; 9-phenylacridine; and azo compounds such as azobisisobutyronitrile, diazonium compounds, and tetragene compounds.

[0104] These may be used as a single type alone, or as a combination of two or more types.

[0105] In order to prevent damage to the finally obtained printing plate and to maintain thickness uniformity during printing, the content of the photopolymerization initiator (b-3) in the photosensitive resin composition layer (b) is preferably 0.1 mass% or more and 10 mass% or less when the total amount of the photosensitive resin composition layer (b) is 100 mass%, more preferably 0.1 mass% or more and 5 mass% or less, and even more preferably 0.3 mass% or more and 5 mass% or less.

[0106] [Auxiliary Additives]

[0107] Auxiliary additive ingredients are not limited to the following, but examples include plasticizers, thermal polymerization inhibitors, antioxidants, light stabilizers, ultraviolet absorbers, dyes, pigments, etc.

[0108] Examples of plasticizers include, but are not limited to the following, liquid dienes such as liquid polybutadiene, liquid polyisoprene, modified liquid polybutadiene, modified liquid polyisoprene, liquid acrylonitrile-butadiene copolymer, liquid styrene-butadiene copolymer; hydrocarbon oils such as naphthenic oil and paraffin oil; conjugated diene rubbers based on liquid dienes such as liquid acrylonitrile-butadiene copolymer and liquid styrene-butadiene copolymer; polystyrene with a number average molecular weight of 2000 or less; and ester-based plasticizers such as sebacic acid ester and phthalic acid ester.

[0109] These plasticizers may have hydroxyl or carboxyl groups. Additionally, these plasticizers may be provided with photopolymerizable reactive groups such as (meth)acryloyl groups.

[0110] The above plasticizer may be used alone or in combination with two or more types.

[0111] In addition, the term "liquid phase" in this specification refers to a state having the property of being easily flow-deformed and also being able to solidify into a deformed shape upon cooling.

[0112] In terms of improving the flexibility of the finally obtained printing plate and improving image uniformity during printing, the plasticizer content in the photosensitive resin composition layer (b) is preferably 0 mass% or more and 30 mass% or less when the total amount of the photosensitive resin composition layer (b) is 100 mass%, more preferably 8 mass% or more and 30 mass% or less, and even more preferably 8 mass% or more and 25 mass% or less.

[0113] As thermal polymerization inhibitors and antioxidants, those commonly used in the field of resin materials or rubber materials can be used, for example, phenolic materials.

[0114] Examples of phenolic materials include, but are not limited to the following: vitamin E, tetrakis-(methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate)methane, 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 3,9-bis-{1,1-dimethyl-2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro(5,5)undecane, 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate, etc.

[0115] Other examples of thermal polymerization inhibitors and antioxidants include phosphine-based materials such as triphenylphosphite.

[0116] The thermal polymerization inhibitor and the antioxidant may be used as a single type or in combination of two or more types.

[0117] Examples of light stabilizers and ultraviolet absorbers include, but are not limited to, known benzophenone-based compounds, salicylate-based compounds, acrylonitrile-based compounds, metal complex salt-based compounds, and hindered amine-based compounds.

[0118] In addition, the dyes and pigments shown below may be used as ultraviolet absorbers.

[0119] Examples of such light stabilizers and ultraviolet absorbers include, but are not limited to, 2-ethoxy-2'-ethyloxalate bis-anilide, 2,2'-dihydroxy-4-methoxybenzophenone, bis(1,2,2,6,6-pentamethyl-4-piperidyl)-decandioate, 1,2,3-benzotriazole, etc.

[0120] Dyes and pigments are effective as coloring agents for improving visibility.

[0121] Examples of dyes include, but are not limited to, water-soluble basic dyes, acid dyes, direct dyes, etc., or water-insoluble sulfur dyes, oil dyes, disperse dyes, etc. Anthraquinone dyes, indigoid dyes, and azo dyes are particularly preferred.

[0122] Examples of pigments include, but are not limited to, natural pigments, synthetic inorganic pigments, and synthetic organic pigments. Examples of synthetic organic pigments include azo pigments, triphenylmethane pigments, quinoline pigments, anthraquinone pigments, and phthalocyanine pigments.

[0123] (Storage modulus of photosensitive resin composition)

[0124] In the method for manufacturing a printing plate according to the present embodiment, after the exposure process, a developing process is performed in which a photosensitive resin composition of an unexposed portion is attached to or adsorbed onto a developing medium to develop.

[0125] At the development temperature of this development process, the storage modulus of the photosensitive resin composition of the unexposed portion is 100 Pa or more and 4000 Pa or less, preferably 100 Pa or more and 350 Pa or less, more preferably 100 Pa or more and 250 Pa or less, and even more preferably 130 Pa or more and 240 Pa or less.

[0126] When the storage modulus of the photosensitive resin composition of the unexposed portion is within the above numerical range, the photosensitive resin composition exhibits appropriate fluidity when in contact with a developing medium; therefore, it tends to achieve both good adsorption to the developing medium and suppression of leakage outside the contact portion with the developing medium. As a result, the removal capability of the unexposed portion is improved, thereby suppressing contamination of the developing device.

[0127] In the method for manufacturing a printing plate of the present embodiment, the developing temperature of the developing process is 0 to 200°C, and the storage modulus of the photosensitive resin composition of the unexposed portion at this developing temperature can be controlled to the above numerical range by adjusting the content of the polymer (b-1), the content of the ethylene unsaturated compound (b-2), and / or the number average molecular weight (Mn) in the photosensitive resin composition.

[0128] (Loss elastic modulus of photosensitive resin composition)

[0129] In the method for manufacturing a printing plate according to the present embodiment, after the exposure process, a developing process is performed in which a photosensitive resin composition of an unexposed portion is attached to or adsorbed onto a developing medium to develop. At the developing temperature of this developing process, the loss modulus of the photosensitive resin composition of the unexposed portion is preferably 90 Pa or more and 500 Pa or less, more preferably 100 Pa or more and 500 Pa or less, and even more preferably 130 Pa or more and 480 Pa or less.

[0130] If the loss modulus is 90 Pa or higher, the photosensitive resin composition does not break easily when the developing medium is separated from the printing plate during the developing process, making it difficult for unexposed photosensitive resin composition to remain as a residue on the printing plate. On the other hand, if the loss modulus is 500 Pa or lower, appropriate fluidity can be obtained in the removal of uncured resin.

[0131] In the method for manufacturing a printing plate of the present embodiment, the developing temperature of the developing process is 0 to 200°C, and the loss elastic modulus of the photosensitive resin composition of the unexposed portion at this developing temperature can be controlled to the above numerical range by adjusting the content of the polymer (b-1), the content of the ethylene unsaturated compound (b-2), and / or the number average molecular weight (Mn) in the photosensitive resin composition.

[0132] The storage modulus and loss modulus described above can be measured by the method described in the examples below.

[0133] (Suitable form of the method for manufacturing the printing plate of the present embodiment)

[0134] Regarding the method of manufacturing the printing plate of the present embodiment, a suitable form is shown below.

[0135] In addition, the method of manufacturing the printing plate of the present embodiment is not limited to the following forms.

[0136] The method for manufacturing a printing plate according to the present embodiment preferably comprises, using the above-described photosensitive resin composition for a printing plate (a photosensitive resin composition laminated on a support), a process of first irradiating ultraviolet rays from the support side (first process); a process of irradiating infrared rays onto an infrared ablation layer to draw a pattern in the case of digital printing, or a process of adhering a negative film to a photosensitive resin composition layer in the case of analog printing (second process); a process of irradiating ultraviolet rays onto a photosensitive resin composition layer to expose a pattern using the infrared ablation layer or negative film with the drawn pattern as a mask (third process); and a process of removing unexposed portions of the photosensitive resin composition layer (fourth process).

[0137] In this (fourth process), in this embodiment, the storage modulus of the photosensitive resin composition and the elastic recovery rate of the developing medium are specified as described above.

[0138] Afterwards, if necessary, a post-exposure treatment process is performed to obtain a printing plate made of a cured photosensitive resin composition layer.

[0139] In addition, from the perspective of imparting peelability, a process may be provided in which the surface of the printing plate is brought into contact with a liquid containing a silicon compound and / or a fluorine compound.

[0140] Process 1

[0141] In the first process, ultraviolet rays are irradiated onto the photosensitive resin composition layer (b) from the support (a) side.

[0142] The ultraviolet irradiation method is not particularly limited and can be irradiated using a known irradiation unit. The wavelength of the ultraviolet light irradiated is preferably 150 nm or more and 500 nm or less, more preferably 300 nm or more and 400 nm or less.

[0143] As a light source for ultraviolet light, examples such as low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, zirconium lamps, carbon arc lamps, and fluorescent lamps for ultraviolet light may be used, although not limited to the following.

[0144] In addition, this first process may be performed before or after the second process described later.

[0145] Process 2

[0146] In the second process, the method of drawing a pattern by irradiating infrared rays onto the infrared ablation layer is not particularly limited and can be performed using a known irradiation unit. Additionally, infrared irradiation onto the infrared ablation layer can be performed from the infrared ablation layer side.

[0147] In the case where the photosensitive resin composition for a printing plate described above has a cover film, the cover film is peeled off first before infrared irradiation. Then, infrared rays are pattern-irradiated onto the infrared ablation layer, and the resin in the infrared irradiation area is decomposed to form a pattern. By doing so, a mask of the infrared ablation layer can be formed on the photosensitive resin composition layer.

[0148] Examples of infrared lasers used in the second process include ND / YAG lasers (e.g., 1064 nm) or diode lasers (e.g., 830 nm). Laser systems suitable for CTP plate making technology are commercially available, and for example, the diode laser system CDI Spark (manufactured by ESKO GRAPHICS) can be used. This laser system includes a rotating cylindrical drum that holds a photosensitive resin composition for a printing plate, an infrared laser irradiation device, and a layout computer, and image information is transmitted directly from the layout computer to the infrared laser irradiation device.

[0149] In the second process, when performing analog plate making, a mask can be formed in the same way by using a negative film.

[0150] Process 3

[0151] The third process involves using an infrared ablation layer or a negative film with a pattern drawn on it as a mask to irradiate a photosensitive resin composition layer with ultraviolet light to perform pattern exposure.

[0152] At this time, ultraviolet rays passing through the mask promote the curing reaction of the photosensitive resin composition layer, and the pattern formed on the infrared ablation layer or negative film is transferred to the photosensitive resin composition layer with the irregularities reversed. The ultraviolet rays may be irradiated over the entire surface or partially irradiated.

[0153] The third process may be performed with the photosensitive resin composition for the printing plate described above attached to the laser cylinder of the laser system, but generally, the photosensitive resin composition for the printing plate is detached from the laser system and irradiated using a conventional irradiation unit. The irradiation unit may be the same unit as exemplified in the ultraviolet irradiation of the first process.

[0154] Process 4

[0155] The fourth process is a process for removing unexposed areas of the photosensitive resin composition layer.

[0156] As a method for removing unexposed areas in the fourth process (development process), the unexposed areas are removed by attaching or adsorbing them to the developing medium.

[0157] The fourth process is performed by heating the photosensitive resin composition for the printing plate after the third process to a temperature of 40°C or higher and 200°C or lower, and accordingly, appropriate fluidity can be imparted to the photosensitive resin composition that is masked by an infrared ablation layer or a negative film and is not irradiated with ultraviolet light, i.e., the unexposed portion.

[0158] When heating a photosensitive resin composition, conventionally known equipment may be used as long as it has the function of heating the photosensitive resin composition layer. For example, both a heating device inserted inside a roll that installs a photosensitive resin composition for a printing plate and a heating device installed outside the roll may be used. Examples include an infrared lamp provided to irradiate infrared rays onto the photosensitive resin composition layer.

[0159] Next, the unexposed portion is removed by attaching or absorbing it onto the developing medium. At this time, as a preliminary step before the removal by adsorption or absorption, a portion of the unexposed portion may be removed in advance using a spatula or roller.

[0160] The developing medium has a predetermined absorption layer, and the absorption layer is brought into contact with an unexposed portion, and the unexposed portion is removed by attaching or absorbing it.

[0161] After that, the printing plate is manufactured by post-exposure treatment as needed.

[0162] In addition, if an intermediate layer is provided between the infrared ablation layer and the photosensitive resin composition layer, it may be removed simultaneously during the development process.

[0163] When the photosensitive resin composition is in a liquid state at room temperature, the first to third processes typically include a predetermined molding process in which the photosensitive resin composition is formed into a film shape of a certain thickness on a support inside a dedicated device (plate-making machine).

[0164] When using a liquid photosensitive resin composition as described above, it is preferable to perform the exposure process of the photosensitive resin composition by carrying out, for example, each of the following processes (A1) to (A3).

[0165] Process of (A1):

[0166] The process of (A1) is a molding process of a photosensitive resin composition layer, wherein a negative film is placed on a UV-transmitting glass plate (lower glass plate), the negative film is covered with a thin protective film, a photosensitive resin composition is poured over it, a base film serving as a support is bonded through a spacer so that the plate thickness is uniform, and a photosensitive resin composition layer is formed by pressing it over the negative film with a UV-transmitting glass plate (upper glass plate).

[0167] For example, when manufacturing a printing plate (thickness of 4 mm or more) used for cardboard printing, it is desirable to form a shelf layer that serves as a foundation on the photosensitive resin composition layer on the upper glass plate side in order to secure sufficient relief strength against printing pressure during printing. In this case, before performing relief exposure, a dedicated negative film (masking film) is inserted between the upper glass plate and the base film to form the photosensitive resin composition layer.

[0168] Process of (A2):

[0169] The process of (A2) is a back exposure process in which, after the molding process of the photosensitive resin composition layer, an active light (e.g., a light having a wavelength distribution of 300 nm or more) is irradiated from the upper glass plate side through the base film using an active light source such as an ultraviolet fluorescent lamp, thereby depositing a uniform thin cured resin layer (i.e., a bottom forming layer (back precipitation layer)) on the front surface of the base film side of the plate.

[0170] In the process of forming a photosensitive resin composition layer, if a masking film is formed, a shelf layer is formed by exposure of the same formula. In this case, it is called a masking exposure process.

[0171] Both the white precipitation layer and the shelf layer are formed by curing the photosensitive resin composition layer on the side opposite to the relief forming layer side, that is, on the base film side. When the photosensitive resin composition layer on the base film side is cured across the entire surface, it becomes the white precipitation layer, and when the photosensitive resin composition layer is cured partially according to the location of the relief forming layer, it becomes the shelf layer.

[0172] Process of (A3):

[0173] The process of (A3) is a relief forming exposure process in which, after a back exposure process or a masking exposure process, an active light such as the one above is irradiated from the lower glass side through a negative film to the photosensitive resin composition layer to precipitate an image forming layer (relief forming layer).

[0174] In addition, when a shelf layer is formed by a masking exposure process, it is also a preferred embodiment to form a white precipitation layer on the entire surface of the base film by removing the masking film after the relief formation exposure process and additionally undergoing a back exposure process.

[0175] (Relief depth)

[0176] In the method for manufacturing a printing plate according to the present embodiment, from the perspective of the removeability of the photosensitive resin composition of the unexposed portion, the thickness of the relief forming layer, i.e., the relief depth, is preferably 0.1 mm or more and 10.0 mm or less, more preferably 0.5 mm or more and 3.0 mm or less, and even more preferably 0.5 mm or more and 2.0 mm or less. Here, the relief depth is the length obtained by subtracting the height of the back precipitation layer and / or shelf layer from the plate thickness, i.e., the depth of the printed image relief.

[0177] That is, if only a white precipitate layer is formed, the height of the white precipitate layer is subtracted from the plate thickness, and if only a shelf layer is formed, the height of the shelf layer is subtracted.

[0178] Since the relief depth is 0.1 mm or more, the required relief depth can be secured when performing design printing. On the other hand, since the relief depth is 10.0 mm or less, in the development process, the contact area with the developing medium relative to the volume of the photosensitive resin composition of the unexposed area can be secured significantly, and the adsorption removal performance of the photosensitive resin composition of the unexposed area becomes good.

[0179] The thickness of the relief forming layer (relief depth) can be controlled to the above numerical range by adjusting the thickness of the shelf layer and / or back precipitation layer by adjusting the exposure amount of the active light in the exposure process of (A2).

[0180] (Developing medium used in the developing process)

[0181] In the method for manufacturing a printing plate according to the present embodiment, in the developing process, a photosensitive resin composition of an unexposed portion is attached to or adsorbed onto a developing medium to perform development.

[0182] It is preferable that the developing medium has an adsorption layer in part or all of it, and as the developing medium, a wiper in which the adsorption layer is formed by, for example, nonwoven fabric, sponge, woven and knitted fabric, paper, etc. is used.

[0183] A nonwoven fabric is preferred as a wiper, for example, in that it is difficult to generate residue from the wiper during the developing process and has excellent removal properties for the photosensitive resin composition of the unexposed light. "Nonwoven fabric" refers to a material formed into a web by bonding or intertwining fibers together through thermal, mechanical, or chemical action.

[0184] The developing medium used in the method for manufacturing a printing plate of the present embodiment shall have an elastic recovery rate of 30% or more and 99% or less.

[0185] During the development process, pressure is applied to the developing medium, but if the elastic recovery rate of the developing medium is low, the developing medium is excessively compressed in the unexposed areas due to that pressure, and the thickness of the final flexographic printing plate decreases, and the thickness uniformity tends to be damaged. As a result, the image uniformity in printing is damaged.

[0186] Since the elastic recovery rate of the developing medium is within the above range, the contact area with the unexposed portion is appropriately maintained, and furthermore, as the pressure decreases, the shape of the developing medium recovers quickly, and as the porosity increases, the unexposed portion is easily adsorbed, allowing the unexposed portion to be removed with less pressure.

[0187] To obtain these effects, the elastic recovery rate of the developing medium is set to be 30% or more and 99% or less, preferably 35% or more and 99% or less, more preferably 40% or more and 99% or less, even more preferably 60% or more and 99% or less, and particularly 69% or more, thereby exhibiting excellent adsorption and removal properties.

[0188] Furthermore, by combining it with the photosensitive resin composition having the storage modulus described above, the removeability of the photosensitive resin composition in the unexposed area is further improved, thereby enabling further improvement in the thickness uniformity of the finally obtained printing plate.

[0189] In addition, the elastic recovery rate of the developing medium can be measured by the method described in the embodiments below.

[0190] The elastic recovery rate of the developing medium can be controlled within the above numerical range by adjusting the temperature when it enters the press roll that performs heat bonding of the constituent materials during the manufacturing process of the developing medium. The method of adjusting the temperature is not particularly limited, but examples include a method of effectively utilizing the heat dissipation of the press roll by means of an insulating plate, or a method of preheating the nonwoven fabric that becomes the developing medium using a preheating roll.

[0191] For example, a thermoplastic resin may be used as the material of the above-mentioned developing medium.

[0192] Examples of thermoplastic resins include polyester resins and / or polyester copolymers and polyamide resins.

[0193] Since the unexposed portion of the photosensitive resin composition layer may be wiped off while heating, it is desirable for the developing medium to have heat resistance, and if the developing medium contains the resin mentioned above, the heat resistance is sufficiently satisfied. In addition, from the perspective of improving the removability of the photosensitive resin composition due to its affinity with the photosensitive resin composition, it is more preferable for the developing medium for thermal development to include a polyester-based resin and / or a polyester-based copolymer.

[0194] Polyester resins are not limited to the following, but examples include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate, polybutylene naphthalate, etc.

[0195] Examples of polyester copolymers include a resin obtained by copolymerizing the above-mentioned polyester resin with a separate polymer, or a resin modified by partially introducing functional groups.

[0196] Polyamide resins are not limited to the following, but examples include nylon 6, nylon 6,6, etc.

[0197] The wiper as a developing medium is preferably a nonwoven fabric having a laminated structure, comprising at least two layers of fiber layers (layer II) with a fiber diameter of 5.0 μm or more and 30.0 μm or less, and comprising an ultrafine fiber layer (layer I) with a fiber diameter of 0.1 μm or more and 5.0 μm as an intermediate layer of the fiber layers (layer II) with a fiber diameter of 5.0 μm or more and 30.0 μm or less.

[0198] The nonwoven fabric having the above laminated structure has a fiber layer with a thick fiber diameter (hereinafter referred to as the thick fiber layer) arranged on the surface layer, and the wiping performance is improved by the scraping effect upon contact with the photosensitive resin composition caused by the uneven shape of the thick fibers present on the surface of the nonwoven fabric. In addition, the wiped-off photosensitive resin composition can pass through the thick fiber layer with high porosity and be retained in the ultrafine fiber layer, thereby enabling the achievement of a long lifespan of repeated uses. Furthermore, by including the ultrafine fiber layer, it is possible to form a dense network structure, which dramatically improves the resin carrying capacity. Since this resin carrying capacity also contributes to suppressing the wiped-off photosensitive resin composition from seeping out, it becomes possible to manufacture a stable flexographic printing plate.

[0199] In addition, the elastic recovery rate of the entire wiper having a laminated structure is determined by the elastic recovery rate of the outermost layer, which is prone to elastic change. For example, in the case of the nonwoven fabric having the laminated structure, the elastic recovery rate of the entire nonwoven fabric having the laminated structure is approximately the same as the elastic recovery rate of the outermost thick fiber layer (Layer II).

[0200] When the developing medium is a nonwoven fabric, the nonwoven fabric may be heat-pressed. In this case, the heat-pressure rate (the area of ​​the compressed portion relative to the area of ​​the nonwoven fabric) is preferably 5% or more and 20% or less, and more preferably 11% or more and 17% or less.

[0201] The method of manufacturing the nonwoven fabric is not particularly limited, and known methods may be used. In addition, the method of producing the above coarse fiber layer (Layer II) is preferably the spunbond method, dry method, wet method, etc. Examples of fibers used for the coarse fiber layer (Layer II) include thermoplastic resin fibers, etc. In addition, the method of producing the above ultrafine fiber layer (Layer I), which is composed of ultrafine fibers with a fiber diameter of 0.1 μm or more and 5.0 μm, may be, for example, the dry method, wet method using ultrafine fibers, or the electrospinning method, melt-blown method, phosphinning, etc. From the viewpoint that the ultrafine fiber layer (Layer I) can be formed easily and densely, the ultrafine fiber layer (Layer I) is particularly preferably formed by the melt-blown method. In addition, the fibers may be used for the manufacture of nonwoven fabrics after realizing split fibers or fibrillation by means of disintegration, partial dissolution, etc.

[0202] Methods for forming a nonwoven fabric having a laminated structure having the aforementioned thick fiber layer (Layer I) and ultrafine fiber layer (Layer II) include, for example, a method of integration by thermal bonding, a method of three-dimensional interlocking by spraying a high-speed water stream, and a method of integration by a particle-type or fiber-type adhesive.

[0203] Methods of integration by thermal bonding include integration by thermal embossing (thermal embossing roll method) and integration by high-temperature hot air (air-through method).

[0204] Integration by thermal bonding is desirable in that it allows for the formation of laminated nonwoven fabrics without the use of a binder.

[0205] Integration by thermal bonding can be achieved, for example, by bonding using a press roll (flat roll or emboss roll) at a linear pressure of 100 to 1000 N / cm at a temperature 50 to 120°C lower than the melting point of the synthetic resin.

[0206] By having a linear pressure of 100 N / cm or more in the heat bonding process, a sufficient bonding effect can be obtained and sufficient strength can be achieved. In addition, by having a linear pressure of 1000 N / cm or less, the deformation of the fibers can be prevented from increasing, and the apparent density can be prevented from increasing or the porosity from decreasing, thereby effectively obtaining the effects according to the present invention.

[0207] In addition, regarding integration by thermal bonding, the subsequent compression characteristics of the nonwoven fabric can be controlled by controlling the temperature of the nonwoven fabric when it enters the press roll. The temperature of the nonwoven fabric when it enters the press roll corresponds to a temperature 50 cm upstream from the roll gripping point. For example, when using polyester, by setting the temperature of the nonwoven fabric when it enters the press roll to a range of 40 to 120°C, it is possible to obtain the elastic recovery rate and compression rate of the nonwoven fabric as described above. By setting the temperature of the nonwoven fabric high in advance as described above, the crystallinity of the yarn is promoted in advance, and accordingly, while securing the minimum amount of amorphous material required for yarn-to-yarn bonding, over-compression at the contact point is suppressed, thereby making it possible to produce a nonwoven fabric with a high elastic recovery rate.

[0208] Methods for adjusting the temperature of the nonwoven fabric to the above-mentioned range are not particularly limited, but examples include a method of effectively utilizing the heat dissipation of the heating press roll by using a predetermined thermal insulation plate, or a method of preheating the nonwoven fabric by using a preheating roll.

[0209] The most preferred method for forming a nonwoven fabric as a developing medium is to sequentially manufacture a spunbond nonwoven fabric layer, a meltblown nonwoven fabric layer, and, if necessary, a spunbond nonwoven fabric layer, laminate them, and then press them with an embossing roll or a heat press roll.

[0210] The above method is desirable when the goal is to obtain a uniform nonwoven fabric with a low basis weight, because it allows for the formation of laminated nonwoven fabrics using the same material and enables production on a continuous, integrated production line.

[0211] Specifically, one or more spunbond nonwoven layers are spun onto a conveyor using a thermoplastic resin, and one or more nonwoven layers containing ultrafine fibers with a fiber diameter of 0.1 to 5 μm are extruded thereon using a thermoplastic resin by the meltblown method. Subsequently, one or more spunbond nonwoven layers composed of thermoplastic resin fibers are laminated using a thermoplastic resin. Then, a method of integrating these layers by calendering using metal rolls is preferred. Examples of the calendering process include compressing the nonwoven layers with heat rolls, and since this method can be carried out on a continuous integrated production line, it is suitable for obtaining nonwoven fabrics with low basis weight or uniformity.

[0212] The heat bonding process can be performed, for example, at a temperature 50°C to 120°C lower than the melting point of the thermoplastic resin and a linear pressure of 100 to 1000 N / cm. If the linear pressure in the calendering process is within the above range, it is desirable from the perspective of improving the strength or porosity of the nonwoven fabric. The heat roll used in the calendering process may be a roll with surface irregularities, such as an embossed or pear peel pattern, or a smooth flat roll. Regarding the surface pattern of the roll with surface irregularities, it is not limited to any pattern that can bond fibers together by heat, such as an embossed pattern, a pear peel pattern, a rectangular pattern, or a line pattern.

[0213] (Recovery and reuse of photosensitive resin composition of unexposed area)

[0214] In the method for manufacturing a printing plate according to the present embodiment, the photosensitive resin composition of the unexposed portion attached to or adsorbed to the developing medium in the above-described developing process may be recovered as a photosensitive resin composition in the manufacture of a new printing plate. This recovered photosensitive resin composition may be reused as a photosensitive resin composition in the manufacture of a new printing plate.

[0215] The recovered photosensitive resin composition may be fed into an exposure machine when manufacturing a new printing plate, and if the photosensitive resin composition is processed and molded before exposure, the photosensitive resin composition recovered from the processing and molding process may be used.

[0216] The exposure machine for introducing the above-mentioned recovered photosensitive resin composition refers to an exposure machine equipped with a unit that laminates a support and a photosensitive resin in a layered shape, and when filling the unit with the photosensitive resin composition, the recovered photosensitive resin composition can be used.

[0217] By utilizing the recovered photosensitive resin composition, waste is reduced, and material costs can also be lowered.

[0218] The method of manufacturing a printing plate of the present embodiment has the following effects (1) to (5).

[0219] (1) The ability to remove unexposed photosensitive resin compositions in the development process is improved.

[0220] (2) Since the balance between the elastic recovery rate of the developing medium and the storage modulus of the photosensitive resin composition is excellent, the photosensitive resin composition with unexposed light can have appropriate fluidity and can also maintain a large amount of the photosensitive resin composition with unexposed light in the voids of the developing medium, thereby achieving high recovery efficiency.

[0221] (3) Since the developing medium has an appropriate elastic recovery rate, the photosensitive resin composition of the unexposed light can be easily separated by applying pressure to the developing medium, thereby improving the recovery rate of the photosensitive resin composition.

[0222] (4) In the development process, the photosensitive resin composition that is not exposed can be removed and recovered without excessive pressure or heating, and thus the deterioration of the photosensitive resin composition can be prevented and furthermore, the incorporation of impurities originating from the development medium can be reduced, so the high-quality photosensitive resin composition can be reused.

[0223] (5) There is less degradation of the photosensitive resin composition residue remaining in the developing medium or the developing medium itself during the developing process, so the frequency of replacing the developing medium can be reduced.

[0224] [Printing Method]

[0225] The printing method of the present embodiment comprises a process of manufacturing a printing plate by the method of manufacturing a printing plate of the present embodiment described above, and a process of printing using the manufactured printing plate.

[0226] In particular, it is a preferred embodiment to manufacture a flexographic printing plate by the method of manufacturing a printing plate of the present embodiment and to perform flexographic printing.

[0227] Examples

[0228] The present invention will be described more specifically below with reference to specific embodiments and comparative examples, but the present invention is not limited in any way by the following embodiments.

[0229] [Physical Properties and Characteristics of Photosensitive Resin Compositions]

[0230] The physical properties and characteristics of the photosensitive resin compositions used in the examples and comparative examples described below are described.

[0231] Storage Modulus and Loss Modulus

[0232] In the case where a photosensitive resin composition that is not fluid at 25°C was used, the composition was kneaded in a pressure kneader at 120°C as a preliminary process, then fed into an extrusion molding machine and extruded from a T-shaped die to a thickness of 3 mm, and then the obtained molded product was punched into a circular shape of 25 mm to be used as a sample for measurement, and the storage modulus and loss modulus were measured under the following measurement conditions.

[0233] In the case where a photosensitive resin composition that is fluid at 25°C was used, the photosensitive resin composition was set directly into the following rheometer without preliminary processing, and the storage modulus and loss modulus were measured under the following measurement conditions.

[0234] In addition, to measure the storage modulus and loss modulus in the development temperature range used in the embodiments described below, measurements were performed at the following measurement temperatures.

[0235] [Measurement Conditions]

[0236] Device: Manufactured by TA Instruments "AR550"

[0237] Geometry: 25 mm

[0238] Normal stress: 0N control

[0239] Measurement temperature: 25–200℃ (temperature change rate 3℃ / min)

[0240] Load deformation: 0.1%

[0241] Frequency: 1 Hz

[0242] Relief Depth

[0243] The thickness of the relief formation layer (relief depth) was measured as follows.

[0244] Using an ABS Digimatic Indicator ID-C112 (manufactured by Mitsutoyo Co., Ltd.), the total thickness of the printing plate, the thickness of the support, and the thickness of the shelf layer or back deposition layer were measured, and the relief depth was calculated using the following formula.

[0245] The relief forming layer is a layer formed in (A3) of the <forming and exposure process> described below.

[0246] The shelf layer is a layer formed in (A2) of the <forming and exposure process> described below.

[0247] The white precipitation layer is a layer formed in (A2) of the <molding and exposure process> described below. Additionally, when the photosensitive resin composition is cured over the entire support, a white precipitation layer is formed, and when only a portion of the photosensitive resin composition is left, a shelf layer is formed.

[0248] Relief depth (mm) =

[0249] Total thickness of printing plate (mm) - (Thickness of white precipitation layer or shelf layer + Thickness of support) (mm)

[0250] [Physical Properties and Characteristics of the Wiper (Non-woven Fabric) of the Developing Media]

[0251] The physical properties and characteristics of the nonwoven fabric used as a wiper for the developing medium in the examples and comparative examples described below are described below.

[0252] <Elastic Recovery Rate>

[0253] The elastic recovery rate of the nonwoven fabric, which is the wiper of the developing medium used in the developing process, was measured as follows.

[0254] The elastic recovery rate of the nonwoven fabric was measured using the MCT-50 microcompression tester manufactured by Shimadzu Seisakusho.

[0255] Measurements were performed under test conditions in a load-unload mode, in which a load up to the maximum test force was applied to the sample for measurement, and then the load was unloaded down to the minimum test force.

[0256] The minimum test force was set to 0.05 mN, and the maximum test force was set to the test force when the nonwoven fabric thickness d was deformed by 10% in compression mode.

[0257] The elastic recovery rate was calculated as follows.

[0258] Elastic recovery rate (%) = L2 / (L1 - L2) × 100

[0259] L1: Displacement difference between maximum and minimum test forces in load mode

[0260] L2: Displacement difference between maximum and minimum test forces in unloading mode

[0261] [Manufacture of Wipers]

[0262] A wiper, which is a developing medium used in the developing process, was manufactured as follows. The wiper was formed from non-woven fabric.

[0263] <Example of Preparation of Nonwoven Fabric 1>

[0264] Polyethylene terephthalate (PET) was extruded from a spunbond spinneret (V-shaped nozzle) at a spinning temperature of 290°C, and the filaments were symmetrically cooled from both sides by a cooling device located directly below the spinneret (both wind speeds of 0.5 m / s), and drawn by a draw jet to obtain continuous long fibers (Layer II, fiber diameter 16 μm), and the fibers were dispersed and deposited on a web conveyor to form a web.

[0265] Next, using a PET solution as an ultrafine fiber layer (Layer I, fiber diameter 3 μm), the material was spun by the meltblown method under conditions of a spinning temperature of 290°C and sprayed onto the web described above. At this time, the distance from the meltblown nozzle to the web was set to 300 mm, and the suction force at the collection surface immediately below the meltblown nozzle was set to 0.2 kPa and the wind speed to 7 m / sec.

[0266] In addition, a continuous long fiber web (layer II, fiber diameter 16 μm) produced by the spunbond method as described above was laminated onto the ultrafine fiber layer (layer I) to obtain a laminated web.

[0267] In addition, nonwoven fabric 1 was produced by integrating the laminated web using a calender roll (roll temperature 220°C, linear pressure 500 N / cm). Furthermore, the position of the insulation plate of the heating roll was adjusted so that the fabric temperature prior to pressing, which is important for controlling compression characteristics, would be the temperature shown in Table 1 below.

[0268] In Table 1 below, "Flat" of the calendar roll types refers to a calendar roll for flat processing, which is a calendar roll capable of applying pressure from the front. "Emboss" refers to a calendar roll for embossing processing, which is a calendar roll capable of applying pressure to only a part of the nonwoven fabric surface by means of a roll with irregularities.

[0269] In addition, in Table 1 below, the heat compression rate is the ratio of the area of ​​the compressed portion to the area of ​​the nonwoven fabric, and the unit is %.

[0270] Manufacturing conditions other than those mentioned above, physical properties of the nonwoven fabric produced, and evaluation results are shown in Table 1 below.

[0271] <Preparation Examples of Nonwoven Fabrics 2, 3, and 4>

[0272] The resin shown in Table 1 below was extruded from a spunbond spinneret (V-shaped nozzle) at a spinning temperature of 290°C, the filaments were cooled symmetrically on both sides by a cooling device directly below the spinneret (both wind speeds of 0.5 m / s), and a continuous long fiber (fiber diameter 16 μm) was obtained by drawing it with a draw jet, and the fibers were dispersed and deposited on a web conveyor to form a web.

[0273] In Table 1 below, "PET / CoPET" is a sheath-core structure fiber of polyester or polyester copolymer.

[0274] In addition, nonwoven fabric 2 was produced by integrating the web using a calender roll (roll temperature 200℃, linear pressure 500 N / cm). Furthermore, the position of the insulation plate of the heating roll was adjusted so that the fabric temperature prior to pressing, which is important for controlling the compression recovery rate, would be the temperature listed in Table 1 below.

[0275] Nonwoven fabric 3 was produced in the same manner as nonwoven fabric 2, except that the fabric temperature before calendering was 71°C and the calender roll temperature was 220°C.

[0276] Nonwoven fabric 4 was produced in the same way as nonwoven fabric 2, except that the resin used was "PET / CoPET" and a plate was used as the type of calender roll.

[0277] Manufacturing conditions other than those mentioned above, physical properties of the nonwoven fabric produced, and evaluation results are shown in Table 1 below.

[0278] <Preparation Examples of Nonwoven Fabrics 5, 6, and 7>

[0279] Fabrics 5 to 7 were produced in the same manner as nonwoven fabric 2, except that the material resin was nylon (nonwoven fabric 5) and polyethylene terephthalate (nonwoven fabrics 6, 7), the fabric temperature before calendering was 24 to 25°C, which is the ambient temperature, and the calender roll temperature in nonwoven fabric 7 was 180°C.

[0280] The manufacturing conditions used, the physical properties of the nonwoven fabric produced, and the evaluation results are shown in Table 1 below.

[0281] In Table 1 below, “Ny” is nylon (polyamide), and “PET” is a sheath-core structure fiber of polyethylene terephthalate.

[0282] In Table 1, the “heat compression rate (%)” under calendar conditions is the area of ​​the compressed portion relative to the nonwoven fabric area.

[0283]

[0284] [Manufacture of Flexographic Printing Plates]

[0285] In the following examples and comparative examples, flexographic printing plates were manufactured using a thermal development system.

[0286] In the following (Preparation Example 1) and (Preparation Example 2), an unsaturated prepolymer composition used in a photosensitive resin composition was prepared.

[0287] (Preparation Example 1) Preparation of unsaturated prepolymer composition A

[0288] 1200 g of hydrogenated 1,2-polybutadiene glycol ("GI-3000" manufactured by Nihon Soda Bushiki Kaisha, hereinafter referred to as "GI-3000") and 0.46 g of dibutyltin dilaurate were added as a diol, and the mixture was stirred at 40°C until homogeneous to obtain a mixture.

[0289] To the obtained mixture, 100 g of tolylene diisocyanate ("Colonate T80" manufactured by Nippon Polyurethane Co., Ltd., hereinafter abbreviated as "TDI") was added and further stirred.

[0290] At the point where it became uniform, the mixture was heated to 80°C and reacted for 4 to 5 hours to prepare a prepolymer precursor having isocyanate groups at both ends.

[0291] To the obtained prepolymer precursor, 600 g of poly(oxypropylene) glycol monomethacrylate ("Brenmar PP" manufactured by Nichiyu Co., Ltd., hereinafter abbreviated as "PPM") was added as a (meth)acrylating agent and reacted for 2 hours to obtain a reaction product.

[0292] A portion of the obtained reaction product was removed, and IR spectroscopy was performed to confirm the loss of isocyanate groups. Thus, unsaturated prepolymer composition A was obtained.

[0293] (Preparation Example 2) Preparation of Unsaturated Prepolymer Composition B

[0294] As a diol, 1200 g of poly(3-methyl-1,5-pentanediol adipate)diol ("Kurapol P3010" manufactured by Kuraray Co., Ltd., hereinafter abbreviated as "P3010"), 800 g of polyoxyethylene (EO)-oxypropylene (PO) block copolymer diol ("Sannix PL2100" manufactured by Sanyo Kasei Kogyo Co., Ltd., hereinafter abbreviated as "PL2100"), 137 g of TDI as an isocyanate, 387 g of PPM as a (meth)acrylating agent, and 0.03 g of dibutyltin dilaurate were used. Other conditions were the same as those in (Preparation Example 1) to obtain unsaturated prepolymer composition B.

[0295] [Examples 1–4, 9–16, Comparative Examples 1, 3]

[0296] To the unsaturated prepolymer composition A of the above (Preparation Example 1), an ethylenically unsaturated compound, a photopolymerization initiator, an antioxidant, etc., as shown in Tables 2 and 3 below were added, and the mixture was stirred and mixed under a heated state of 60°C to obtain a photosensitive resin composition as shown in Table 3 below.

[0297] Using the obtained photosensitive resin compositions 1 to 4 and 9, a flexographic printing plate was produced by sequentially undergoing the molding and exposure process, the developing process, the post-exposure process, and the drying process shown below.

[0298] Forming and Photolithography Processes

[0299] Molding and exposure of the photosensitive resin composition were performed using the “ALF-213E type plate-making machine” manufactured by Asahi Kasei Kabushiki Kaisha in (A1) to (A3).

[0300] (A1):

[0301] A negative film was placed on a UV-transmitting glass plate (lower glass plate), covered with a thin protective film, and then a photosensitive resin composition was poured over it. A base film serving as a support was bonded through spacers to achieve a uniform plate thickness, and a photosensitive resin composition layer was formed by pressing it over with a UV-transmitting glass plate (upper glass plate). To supplement the relief strength against printing pressure during printing, a foundation shelf layer was formed on the portion of the photosensitive resin composition layer on the upper glass plate side. Prior to relief exposure, a dedicated negative film (masking film) was inserted between the upper glass plate and the base film to form the photosensitive resin composition layer.

[0302] (A2):

[0303] After molding the photosensitive resin composition layer, an active light (a light having a wavelength distribution of 300 nm or more) using an active light source such as an ultraviolet fluorescent lamp was irradiated through the base film from the upper glass plate side.

[0304] Since a masking film was placed during the process of forming the photosensitive resin composition layer, a shelf layer was formed by masking exposure.

[0305] (A3):

[0306] After the masking exposure process, a relief formation exposure process was performed on the photosensitive resin composition layer by irradiating an active light of the same type as the upper one through a negative film from the lower glass side to form an image, thereby obtaining a relief formation layer.

[0307] A photosensitive resin composition layer having a negative film (masking film) for a shelf layer was formed as in (A1) above.

[0308] Here, as the negative film (masking film), a shelf layer of 300 mm × 500 mm is formed, and as the negative film for forming relief, a design is implemented in which a linear non-exposed area of ​​500 μm width (hereinafter referred to as "white cutout" or "white cutout line") is formed within a solid image of 200 mm × 250 mm.

[0309] Next, a photosensitive resin composition layer was exposed in the same manner as (A2) and (A3) above to obtain a flexographic printing plate with a plate thickness of 3 mm and a relief depth as described in Table 4 below.

[0310] To adjust the relief depth, the masking exposure amount was appropriately adjusted.

[0311] In the relief formation exposure process, the exposure amount is 300 mJ / cm² 2 It was carried out by...

[0312] <Development Process>

[0313] After recovering and removing the unexposed photosensitive resin composition using a rubber spatula, the flexographic printing plate after exposure was fixed to a metal roll with a diameter of 35 cm driven by a motor using double-sided adhesive tape.

[0314] The nonwoven fabrics shown in Tables 1, 4, and 5 below were installed to pass between a plurality of heatable metal rolls with a diameter of 5 cm.

[0315] The metal roll was rotated by the motor at 2 rpm.

[0316] On a metal roll, 1.0×10 5 The nonwoven fabric was brought into contact with the surface of the photosensitive resin composition layer of the flexographic printing plate and passed through with a contact pressure of Pa.

[0317] The flexographic printing plate was brought into contact with the nonwoven fabric until the photosensitive resin composition of the unexposed portion was not adhered to the nonwoven fabric, thereby removing the unexposed portion of the photosensitive resin composition layer.

[0318] The above development process was carried out in a 25℃ environment.

[0319] Post-exposure process

[0320] Post-exposure was performed using the underwater exposure method with the "AL-200UP type post-exposure machine" manufactured by Asahi Kasei Kabushiki Kaisha, which is equipped with both ultraviolet fluorescent lamps and germicidal lamps.

[0321] The exposure amount irradiated from each light source, at the plate surface: UV fluorescent lamp: 2000 mJ / cm² 2 , Sterilization lamp: 2000 mJ / cm² 2 Post-exposure was performed with an exposure time of [unclear].

[0322] Drying Process

[0323] Using an "ALF-DRYER" manufactured by Asahi Kasei Kabushiki Kaisha, the plate after post-exposure was dried for about 30 minutes until the moisture on the surface was removed, and a flexographic printing plate was obtained.

[0324] [Examples 17, 18]

[0325] With a plate thickness of 12 mm, in the relief formation exposure process, the exposure amount is 600 mJ / cm² 2 Except for the above, a flexographic printing plate was obtained in the same manner as the manufacturing process of Example 1 described above.

[0326] [Examples 5–7]

[0327] The unsaturated prepolymer composition is set to the unsaturated prepolymer composition B of Preparation Example 2, and photosensitive resin compositions 5 to 7 are used to apply an exposure amount of 600 mJ / cm² in a relief-forming exposure process. 2 Except for the above, a flexographic printing plate was obtained in the same manner as the manufacturing process of Example 1 described above.

[0328] [Example 8, Comparative Example 2]

[0329] (Manufacture of a laminate of a support and a photosensitive resin composition layer)

[0330] <Preparation Examples of Photosensitive Resin Compositions 8 and 10>

[0331] The raw materials listed in Table 3 below were kneaded in a pressure kneader at 160°C to obtain photosensitive resin compositions 8 and 10.

[0332] <Preparation of a laminate of a photosensitive resin composition layer and a support using photosensitive resin compositions 8 and 10>

[0333] Next, a photosensitive resin composition was fed into an extrusion molding machine, a support (polyethylene terephthalate film) was bonded to one side of a photosensitive resin composition layer extruded from a T-shaped die, and a release film (manufactured by Mitsubishi Chemical, Diafoil MRV100) was bonded to the side opposite to the laminated side of the photosensitive resin composition layer, thereby obtaining a laminate of the support and the photosensitive resin composition layer.

[0334] (Manufacturing of infrared ablation layer laminates)

[0335] 7.8 parts by mass of Tafpren 315 (manufactured by Asahi Kasei, styrene-butadiene block copolymer), 70.4 parts by mass of toluene, and 7.6 parts by mass of propylene glycol 1-monomethyl ether 2-acetate (PMA)1 were mixed, and Tafpren 315 was dissolved in a solvent.

[0336] After that, carbon black (manufactured by Mitsubishi Chemical, #30) was added and mixed with a bead mill for 4 hours to obtain a carbon black dispersion.

[0337] The carbon black dispersion obtained as described above was coated onto a PET film with a thickness of 100 μm, which serves as a cover film, such that the film thickness after drying is 2.5 μm, and a drying treatment was performed at 90°C for 2 minutes to obtain an infrared ablation layer laminate, which is a laminate of an infrared ablation layer and a cover film.

[0338] (Preparation of the flexographic printing plates of Example 8 and Comparative Example 2)

[0339] A release film was removed from a laminate of a 300 mm × 500 mm support and a photosensitive resin composition layer, and an infrared ablation layer laminate was laminated in an environment of 25°C and 40% humidity so that the infrared ablation layer was in contact with the photosensitive resin composition layer, and a cover film surface was placed on a hot plate set to 120°C so as to contact the heating part of the hot plate, and heat was applied for 1 minute to obtain a photosensitive resin composition 1 for a flexographic printing plate.

[0340] The cover film of the photosensitive resin composition 1 for a flexographic printing plate produced as described above was removed, and the composition was mounted on an Esko CDI SPARK2530 to draw a design in which a white cutout line with a width of 500 μm is formed within a solid image of 200 mm × 250 mm at a laser intensity of 3.8 J.

[0341] On the "AFP-1216E" exposure machine (manufactured by Asahi Kasei Co., Ltd., product name), using a lower ultraviolet lamp (UV lamp TL80W / 10R manufactured by PHILIPS, product name), first, at 530 mJ / cm², so that the relief depth of the flexographic printing plate finally obtained from the support side becomes 2.0 mm. 2 A white precipitate layer was formed by exposing the front surface to light.

[0342] Next, using the upper lamp (PHILIPS TL80W / 10R UV lamp, product name), 8000 mJ / cm² from the cover film side 2 Ultraviolet light was irradiated and pattern exposure was performed to obtain a flexographic printing plate. In addition, the exposure intensity at this time was measured using a UV illuminance meter MO-2 type manufactured by Okusei Sakusho (Okusei Sakusho, product name, UV-35 filter).

[0343] The flexographic printing plate after exposure was fixed to a metal roll with a diameter of 35 cm driven by a motor using double-sided adhesive tape.

[0344] The nonwoven fabrics shown in Tables 1, 4, and 5 were installed to pass between a plurality of heatable metal rolls with a diameter of 5 cm.

[0345] An infrared lamp for heating a photosensitive resin composition layer relatively quickly was fixed on the metal roll holding the flexographic printing plate.

[0346] An infrared lamp was turned on, and a metal roll heated to 170°C was slowly rotated (2 rpm) by a motor. On the metal roll, 1.0 × 10 5 The nonwoven fabric was brought into contact with the surface of the photosensitive resin composition layer of the flexographic printing plate and passed through with a contact pressure of Pa.

[0347] The flexographic printing plate was brought into contact with the nonwoven fabric until the photosensitive resin composition of the unexposed portion was not adhered to the nonwoven fabric, thereby removing the unexposed portion of the photosensitive resin composition layer.

[0348] [Evaluation of Flexographic Printing Plates]

[0349] <Evaluation of White Cutout Depth (Residue)>

[0350] Using the μDEPTH & HEIGHT MEASURING SCOPE KY-90 (manufactured by Nissho Seimitsu Kogaku Co., Ltd.), the groove shape of a white cutout line with a width of 500 μm was observed and the depth of the groove was measured.

[0351] The evaluation criteria for the measurement results are shown below.

[0352] Based on the evaluation criteria below, A to D were evaluated as being usable without practical problems.

[0353] (metewand)

[0354] A: Depth 151 µm or greater

[0355] B: Depth less than 121–151 µm

[0356] C: Depth less than 91–121 µm

[0357] D: Depth less than 70–91 µm

[0358] E: Depth less than 70 µm

[0359] <Evaluation of Thickness Uniformity Based on Thickness Precision>

[0360] Using the ABS Digimatic Indicator ID-C112 (manufactured by Mitsutoyo Co., Ltd.), the plate thickness of the solid image portion of the flexographic printing plate was measured at 9 random points, and the difference between the maximum and minimum values ​​was calculated as thickness precision to evaluate thickness uniformity.

[0361] Based on the evaluation criteria below, A to D was evaluated as being usable without practical problems.

[0362] (metewand)

[0363] A: Thickness precision less than 0.05 mm

[0364] B: Thickness precision 0.05 mm or more and less than 0.07 mm

[0365] C: Thickness precision 0.07 mm or more, less than 0.10 mm

[0366] D: Thickness precision 0.10 mm or more, less than 0.15 mm

[0367] E: Thickness precision 0.15 mm or greater

[0368] <Evaluation of Recovery Rate of Photosensitive Resin Composition>

[0369] The recovery rate of the photosensitive resin composition was calculated using the following formula based on the mass ratio of the unexposed photosensitive resin composition extracted from the nonwoven fabric used in the above-described manufacturing method, when the mass obtained by subtracting the mass of the flexographic printing plate produced by developing with a developer from the sum of the mass of the photosensitive resin composition and the mass of the support used in the manufacture of the flexographic printing plate was set to 100.

[0370] Recovery rate of photosensitive resin composition (%) = (Mass of unexposed photosensitive resin composition extracted from nonwoven fabric after development) / {(Mass of photosensitive resin composition used in the manufacture of flexographic printing plates) + (Mass of support) - (Mass of flexographic printing plates manufactured by developer development)} × 100

[0371] Based on the following evaluation criteria, if it is ○ or ◎, it is evaluated as being usable without practical problems.

[0372] (metewand)

[0373] ◎: Recovery rate of photosensitive resin composition of 80% or more

[0374] ○: Recovery rate of photosensitive resin composition 40% or more and less than 80%

[0375] ×: Recovery rate of photosensitive resin composition less than 40%

[0376] [Examples 5, 5-2, 5-3, Comparative Examples 4, 5]

[0377] In Examples 5-2, 5-3, and Comparative Examples 4 and 5, flexographic printing plates were produced by the same method as in Example 5, except that the developing method and the photosensitive resin composition were changed as shown in Table 6 below, respectively.

[0378] In Examples 5, 5-2, 5-3 and Comparative Examples 4 and 5, the following methods 1 to 4 were adopted as the developing method for evaluating the recovery rate of the photosensitive resin composition.

[0379] (Development method)

[0380] 1: It is carried out using the method described in Example 1.

[0381] 2: The photosensitive resin composition of the unexposed light is developed by contact only with the nonwoven fabric without using a rubber spatula.

[0382] 3: The photosensitive resin composition of the unexposed light is developed using only a rubber spatula to remove it.

[0383] 4: Develop using the developer solution.

[0384] In the above-described evaluation, development using the developer solution was performed by combining an aqueous solution containing 2 mass% of "APR (registered trademark) cleaning agent type W-13" manufactured by Asahi Kasei Co., Ltd. (drum rotary spray type, drum rotation speed: 20 rotations / min, spray pressure: 0.15 Pa), which is capable of emulsifying a photosensitive resin composition, 0.6 mass% of "APR (registered trademark) surface treatment agent type A-10" manufactured by Asahi Kasei Co., Ltd., and 0.3 mass% of "defoamer SH-4" (silicone mixture) manufactured by Asahi Kasei Co., Ltd., as the developer solution, and under conditions of liquid temperature 40°C and development time 15 minutes.

[0385] After development, rinsed with tap water until the foam caused by the developer disappeared.

[0386] The recovery rate of the photosensitive resin composition obtained from the above-described development method and the above-described formula is summarized in Table 6.

[0387] At this time, “Photosensitive resin composition No. 5’” in Table 6 represents an unexposed photosensitive resin composition (recovered photosensitive resin composition) recovered after being removed by a rubber spatula and a nonwoven fabric.

[0388] In addition, among Table 6, (Example 5-2) is an example in which the developing method in the manufacturing process of the flexographic printing plate of Example 5 is changed to the developing method of 2 above. (Example 5-3) is an example in which a recovered photosensitive resin composition is used as the photosensitive resin composition in the manufacturing process of the flexographic printing plate of Example 5. In addition, (Comparative Example 4) is an example in which the developing method in the manufacturing process of the flexographic printing plate of Example 5 is changed to the developing method of 3 above. (Comparative Example 5) is an example in which the developing method in the manufacturing process of the flexographic printing plate of Example 5 is changed to the developing method of 4 above.

[0389]

[0390]

[0391]

[0392]

[0393]

[0394] This application is based on Japanese patent application (JP 2021-164482) filed with the Japan Patent Office on October 6, 2021, the contents of which are incorporated herein by reference. Industrial applicability

[0395] The method for manufacturing a printing plate of the present invention has industrial applicability in the general commercial printing field.

Claims

Claim 1 A method for manufacturing a printing plate comprising: a molding process for molding a photosensitive resin composition that is in a liquid state at room temperature; an exposure process for forming a relief by exposure to light on the molded photosensitive resin composition; and a developing process for developing the photosensitive resin composition of an unexposed portion in the exposure process by attaching or adsorbing it to a developing medium, wherein, at the developing temperature of the developing process, the storage modulus of the photosensitive resin composition of the unexposed portion is 100 Pa or more and 350 Pa or less, and the developing medium is a wiper having an elastic recovery rate of 40% or more and 99% or less; the photosensitive resin composition comprises an unsaturated prepolymer or thermoplastic elastomer binder which is a polyurethane having (meth)acrylic groups at the terminals; the photosensitive resin composition further comprises an ethylene unsaturated compound, and the content of the ethylene unsaturated compound is 2 mass% or more and 60 mass% when the total amount of the photosensitive resin composition is 100 mass%. A method for manufacturing a printing plate, wherein the mass percentage is less than Claim 2 delete Claim 3 A method for manufacturing a printing plate according to claim 1, wherein the storage modulus of the photosensitive resin composition of the unexposed portion at the development temperature is 100 Pa or more and 250 Pa or less. Claim 4 A method for manufacturing a printing plate according to claim 1 or 3, wherein the loss elastic modulus of the photosensitive resin composition of the unexposed portion at the development temperature is 90 Pa or more and 500 Pa or less. Claim 5 delete Claim 6 delete Claim 7 A method for manufacturing a printing plate according to claim 1 or 3, wherein the developing medium is a wiper having an elastic recovery rate of 60% or more and 99% or less. Claim 8 A method for manufacturing a printing plate according to claim 1 or 3, wherein the relief depth of the printing plate is 0.1 mm or more and 10.0 mm or less. Claim 9 A method for manufacturing a printing plate according to claim 1 or 3, wherein the wiper is a nonwoven fabric. Claim 10 A method for manufacturing a printing plate according to claim 1 or 3, comprising a process of recovering the photosensitive resin composition of the unexposed portion attached to or adsorbed on the developing medium as a photosensitive resin composition in the manufacture of a new printing plate. Claim 11 A method for manufacturing a printing plate according to claim 1 or 3, wherein the photosensitive resin composition of the unexposed portion attached to or adsorbed on the developing medium is recovered and used as a photosensitive resin composition in the manufacture of a new printing plate. Claim 12 A printing method comprising a process for manufacturing a printing plate using the method for manufacturing a printing plate described in claim 1 or 3, and a printing process for printing using the manufactured printing plate.

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