Photosensitive resin component for flexographic printing plates, and method for manufacturing flexographic printing plates

Abstract

To provide a photosensitive resin structure for a flexographic printing plate which has an infrared ablation layer that enables drawing with a high resolution, and facilitates peeling of a cover film even after being left at high temperature.SOLUTION: A photosensitive resin structure for a flexographic printing plate includes at least a support (a), a photosensitive resin composition layer (b) stacked on the support (a), an infrared ablation layer (c) stacked on the photosensitive resin composition layer (b), a peeling force adjustment layer (d) stacked on the infrared ablation layer (c), and a cover film (f) stacked on the peeling force adjustment layer (d), wherein the infrared ablation layer (c) includes a resin having a structural unit c1 represented by general formula [-(CR3R4-CR1R2)-].SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photosensitive resin structure for flexographic printing plates and a method for manufacturing flexographic printing plates. [Background technology]

[0002] In recent years, there has been a growing demand for even higher resolution printed images. Meanwhile, in the manufacturing process of flexographic printing plates, the CTP (Computer To Plate) technology has been widely used to directly draw digital images with a laser without using negative film.

[0003] In this CTP technology, the master plate for manufacturing flexographic printing plates is generally made by sequentially laminating a photosensitive resin composition layer, an infrared ablation layer that can be removed with infrared light, and a cover film on a substrate such as PET (polyethylene terephthalate) resin.

[0004] The cover film is peeled off during use, but when the infrared ablation layer was changed to achieve higher resolution in printed images, there was a problem with the peelability deteriorating.

[0005] Therefore, Patent Document 1 proposes a technique for laminating a peel force adjusting layer containing an anionic surfactant onto a cover film in order to improve peelability.

[0006] Furthermore, Patent Document 2 proposes a peeling force adjusting layer containing an amino resin. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2009-139599 [Patent Document 2] Japanese Patent Publication No. 2013-114136 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, even with the aforementioned peeling force adjustment layer, it was not possible to sufficiently lightly peel off the infrared ablation layer, which allows for higher resolution drawing, and in particular, peeling off the cover film became difficult if it was left in an environment above 30°C for a long time.

[0009] Therefore, in view of the problems of the prior art described above, the present invention aims to provide a photosensitive resin structure for flexographic printing plates that has an infrared ablation layer capable of high-resolution drawing and allows for easy peeling of the cover film even after being left at high temperatures, and a method for manufacturing a flexographic printing plate using the same. [Means for solving the problem]

[0010] The inventors of the present invention conducted extensive research to solve the above problems and found that the above problems can be solved by a photosensitive resin structure for flexographic printing plates having a specific infrared ablation layer and a peeling force adjusting layer, thus completing the present invention.

[0011] In other words, the present invention is as follows. [1] At a minimum, support (a) and A photosensitive resin composition layer (b) is laminated on the support (a), An infrared ablation layer (c) laminated on the photosensitive resin composition layer (b), A peel force adjusting layer (d) is laminated on the infrared ablation layer (c), A cover film (f) is laminated on the peel force adjustment layer (d), Equipped with, The infrared ablation layer (c) contains a resin having a constituent unit c1 represented by the following general formula (1), In analysis by time-of-flight secondary ion mass spectrometry (TOF-SIMS), the peeling force adjustment layer (d) was found to be When the intensity of C2H (m / z = 25) is set to 1 for negative ions and the intensity of C2H3 (m / z = 27) is set to 1 for positive ions, the intensity of C2N3 (m / z = 66) is 0.30 or more and 7.00 or less, the intensity of C6H5 (m / z = 77) is 0.05 or more and 0.40 or less, A photosensitive resin composition for flexographic printing plates.

Chemical formula

[0012] According to the present invention, it is possible to provide a photosensitive resin structure for flexographic printing plates having an infrared ablation layer capable of high-resolution drawing and in which the cover film can be easily peeled off even after being left at high temperatures, and a method for manufacturing a flexographic printing plate using the same. [Brief explanation of the drawing]

[0013] [Figure 1] An example of a schematic cross-sectional view of a photosensitive resin component for flexographic printing plates is shown. [Figure 2] An example of a schematic diagram illustrating a method for manufacturing a flexographic printing plate using a photosensitive resin component for flexographic printing plates is shown. [Modes for carrying out the invention]

[0014] The following describes in detail an embodiment of the present invention (hereinafter referred to as "this embodiment"), but the present invention is not limited thereto, and various modifications are possible without departing from its essence.

[0015] [Photosensitive resin composition for flexographic printing plates] The photosensitive resin structure for flexographic printing plates of this embodiment comprises at least a support (a), a photosensitive resin composition layer (b) laminated on the support (a), an infrared ablation layer (c) laminated on the photosensitive resin composition layer (b), a peel force adjusting layer (d) laminated on the infrared ablation layer (c), and a cover film (f) laminated on the peel force adjusting layer (d).

[0016] Figure 1 shows a schematic cross-sectional view of the photosensitive resin structure for flexographic printing plates according to this embodiment (hereinafter also simply referred to as "this structure"). This structure consists of a support (a), a photosensitive resin composition layer (b) on which the uneven pattern of the flexographic printing plate is formed, an infrared ablation layer (c) that functions as a mask during the formation of the uneven pattern, and a peel force adjusting layer (d) that reduces the peel force of the cover film (f), all of which are laminated together. Other layers may be provided between each layer as needed. This structure will be described in detail below.

[0017] (Support (a)) The support (a) used in this structure is not particularly limited, but examples include polyester film, polyamide film, polyacrylonitrile film, polyvinyl chloride film, etc.

[0018] Among these, polyester film is preferred as the support (a). The polyester used for the support (a) is not particularly limited, but examples include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.

[0019] The thickness of the support (a) is not particularly limited, but is preferably 50 to 300 μm.

[0020] Furthermore, an adhesive layer may be provided on the support (a) to enhance 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 layer described in WO2004 / 104701.

[0021] (Photosensitive resin composition layer (b)) This structure has a photosensitive resin composition layer (b) on a support (a). The photosensitive resin composition layer (b) may be directly laminated on the support (a), or it may be indirectly laminated via the adhesive layer or the like.

[0022] The photosensitive resin composition layer (b) is not particularly limited, but for example, it contains a thermoplastic elastomer (b-1), and preferably further contains an ethylenically unsaturated compound (b-2), a photopolymerization initiator (b-3), and a liquid diene. Furthermore, the photosensitive resin composition layer (b) may optionally contain additional auxiliary components. Each component will be described in detail below.

[0023] <Thermoplastic elastomer (b-1)> The thermoplastic elastomer (b-1) is not particularly limited, but examples include copolymers having structural units derived from monovinyl-substituted aromatic hydrocarbons and structural units derived from conjugated dienes. The thermoplastic elastomer (b-1) may further have structural units derived from other monomers. By using such a thermoplastic elastomer, the print durability of flexographic printing plates manufactured using this structure tends to be further improved.

[0024] The thermoplastic elastomer (b-1) may be a random copolymer or a block copolymer, but a block copolymer having a polymer block made of a monovinyl-substituted aromatic hydrocarbon and a polymer block made of a conjugated diene is preferred. Using such a thermoplastic elastomer tends to further improve the print durability of flexographic printing plates manufactured using this structure.

[0025] The monovinyl-substituted aromatic hydrocarbons constituting the thermoplastic elastomer (b-1) are not particularly limited, but examples include styrene, t-butylstyrene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene, vinylpyridine, p-methylstyrene, p-methoxystyrene, tertiary butylstyrene, α-methylstyrene, and 1,1-diphenylethylene. These may be used individually or in combination of two or more.

[0026] Among these, styrene is preferred as the monovinyl-substituted aromatic hydrocarbon from the viewpoint that the photosensitive resin composition layer (b) can be molded smoothly at a relatively low temperature.

[0027] The conjugated dienes constituting the thermoplastic elastomer (b-1) are not particularly limited, but examples include butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, chloroprene, etc. These may be used individually or in combination of two or more.

[0028] Among these, butadiene is preferred as the conjugated diene from the viewpoint of print durability of flexographic printing plates manufactured using this structure.

[0029] The number-average molecular weight (Mn) of the thermoplastic elastomer (b-1) is preferably 20,000 to 300,000, and more preferably 50,000 to 200,000, from the viewpoint of viscosity at room temperature. The number-average molecular weight can be measured by gel permeation chromatography (GPC) and is expressed as polystyrene-equivalent molecular weight.

[0030] When thermoplastic elastomer (b-1) is a block copolymer having a polymer block made of a monovinyl-substituted aromatic hydrocarbon and a polymer block made of a conjugated diene, thermoplastic elastomer (b-1) includes, for example, linear block copolymers represented by the following general formula group (I), and / or linear block copolymers or radial block copolymers represented by the following general formula group (II).

[0031] General formula group (I): (AB) n , A-(BA) n , A-(BA) n -B, B-(AB) n

[0032] General formula group (II): [(A - B) k m -X, [(A - B) k -A] m -X, [(B - A) k m -X, [(B - A) k -B] m -X

[0033] In general formula groups (I) and (II), A represents a polymer block composed of a monovinyl-substituted aromatic hydrocarbon. Also, B represents a polymer block composed of a conjugated diene. X represents the residue of a coupling agent such as silicon tetrachloride, tin tetrachloride, epoxidized soybean oil, polyhalogenated hydrocarbon compound, carboxylic acid ester compound, polyvinyl compound, bisphenol type epoxy compound, alkoxysilane compound, halogenated silane compound, ester-based compound, etc., or the residue of a polymerization initiator such as a polyfunctional organic lithium compound.

[0034] In general formula groups (I) and (II), n, k, and m represent integers of 1 or more, for example, integers from 1 to 5.

[0035] The contents of the conjugated diene and the monovinyl-substituted aromatic hydrocarbon in the thermoplastic elastomer (b-1) can be measured using a nuclear magnetic resonance apparatus ( 1 H-NMR). Specifically, 1 As the measuring instrument for

[0036] ​​In the thermoplastic elastomer (b-1), the copolymerization ratio (mass ratio) of monovinyl-substituted aromatic hydrocarbons and conjugated dienes is preferably 10 / 90 to 90 / 10, more preferably 10 / 90 to 85 / 15, and even more preferably 10 / 90 to 60 / 40, from the viewpoint of print durability of flexographic printing plates manufactured using this construct.

[0037] In the above copolymerization ratio (mass ratio), if the proportion of monovinyl-substituted aromatic hydrocarbons is 10 or more, sufficient hardness can be obtained in the photosensitive resin composition layer (b), and appropriate printing can be performed with normal printing pressure. Furthermore, if the proportion of monovinyl-substituted aromatic hydrocarbons is 90 or less in the above copolymerization ratio (mass ratio), appropriate hardness can be obtained in the photosensitive resin composition layer (b), and the ink can be sufficiently transferred to the printing target during the printing process.

[0038] The thermoplastic elastomer (b-1) may, if necessary, have other functional groups introduced, undergo chemical modifications such as hydrogenation, or have other components copolymerized into it.

[0039] From the viewpoint of print durability of the flexographic printing plate obtained using this structure, the content of thermoplastic elastomer (b-1) in the photosensitive resin composition layer (b) is preferably 40% by mass or more, more preferably 40 to 80% by mass, even more preferably 45 to 80% by mass, and even more preferably 45 to 75% by mass, when the total amount of the photosensitive resin composition layer (b) is 100% by mass.

[0040] <Ethylene-unsaturated compounds (b-2)> The photosensitive resin composition layer (b) preferably contains an ethylenically unsaturated compound (b-2), as described above. An ethylenically unsaturated compound (b-2) is a compound having a radically polymerizable unsaturated double bond.

[0041] Such ethylenically unsaturated compounds (b-2) are not particularly limited, but examples include 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; and N-substituted maleimide compounds.

[0042] Among these, (meth)acrylic acid and / or its derivatives are preferred as the ethylenically unsaturated compound (b-2) from the viewpoint of UV curability and print resistance of the photosensitive resin composition layer (b) after curing.

[0043] The above derivatives are not particularly limited, but examples include: alicyclic compounds having cycloalkyl groups, bicycloalkyl groups, cycloalkenyl groups, bicycloalkenyl groups, etc.; aromatic compounds having benzyl groups, phenyl groups, phenoxy groups, or naphthalene skeletons, anthracene skeletons, biphenyl skeletons, phenanthrene skeletons, fluorene skeletons, etc.; compounds having alkyl groups, halogenated alkyl groups, alkoxyalkyl groups, hydroxyalkyl groups, aminoalkyl groups, glycidyl groups, etc.; ester compounds with alkylene glycols, polyoxyalkylene glycols, polyalkylene glycols, and polyhydric alcohols such as trimethylolpropane; and compounds having a polysiloxane structure such as polydimethylsiloxane and polydiethylsiloxane.

[0044] Furthermore, the ethylenically unsaturated compound (b-2) may be a heteroaromatic compound containing elements such as nitrogen and sulfur.

[0045] The above-mentioned (meth)acrylic acid and / or derivatives are not particularly limited, but examples include diacrylates and dimethacrylates of alkanediols such as hexanediol and nonanediol; diacrylates and dimethacrylates of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, and butylene glycol; trimethylolpropane tri(meth)acrylate; dimethylol tricyclodecane di(meth)acrylate; isobolonyl(meth)acrylate; phenoxypolyethylene glycol(meth)acrylate; pentaerythritol tetra(meth)acrylate, etc. These may be used individually or in combination of two or more.

[0046] From the viewpoint of the mechanical strength of the flexographic printing plate obtained using this structure, it is preferable to use at least one (meth)acrylate as the ethylenically unsaturated compound (b-2), and more preferable to use at least one bifunctional (meth)acrylate.

[0047] The number-average molecular weight (Mn) of the ethylenically unsaturated compound (b-2) is preferably 100 or more from the viewpoint of improving the non-volatility of the ethylenically unsaturated compound (b-2) during the production and / or storage of this construct, preferably less than 1000 from the viewpoint of compatibility with other components, and more preferably between 200 and 800.

[0048] From the viewpoint of print durability of the flexographic printing plate obtained using this structure, the content of the ethylenically unsaturated compound (b-2) in the photosensitive resin composition layer (b) is preferably 2% by mass or more and 30% by mass or less, more preferably 2% by mass or more and 25% by mass or less, and even more preferably 2% by mass or more and 20% by mass or less, when the total amount of the photosensitive resin composition layer (b) is 100% by mass.

[0049] <Photopolymerization initiator (b-3)> The photosensitive resin composition layer (b) preferably contains a photopolymerization initiator (b-3). The photopolymerization initiator (b-3) is a compound that absorbs light energy and generates radicals, and examples include disintegrating photopolymerization initiators, hydrogen abstraction photopolymerization initiators, and compounds that have a part that functions as a hydrogen abstraction photopolymerization initiator and a part that functions as a disintegrating photopolymerization initiator within the same molecule.

[0050] Such photopolymerization initiators (b-3) are not particularly limited, but examples include benzophenones such as benzophenone, 4,4-bis(diethylamino)benzophenone, 3,3',4,4'-benzophenonetetracarboxylic anhydride, and 3,3',4,4'-tetramethoxybenzophenone; anthraquinones such as t-butylanthraquinone and 2-ethylanthraquinone; thioxanthones such as 2,4-diethylthioxanthone, isopropylthioxanthone, and 2,4-dichlorothioxanthone; Michler ketones; diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, and 2-methyl-1-(4 Examples include acetophenones such as -methylthiophenyl)-2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, and trichloroacetophenone; benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; 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 tetrazene compounds. These may be used individually or in combination of two or more.

[0051] Among these, from the viewpoint of print durability of flexographic printing plates manufactured using this composition, compounds having a carbonyl group are preferred as the photopolymerization initiator (b-3), and aromatic carbonyl compounds such as benzophenones and thioxanthones are more preferred.

[0052] From the viewpoint of print durability of flexographic printing plates manufactured using this construct, the content of the photopolymerization initiator (b-3) in the photosensitive resin composition layer (b) is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less, and even more preferably 0.5% by mass or more and 5% by mass or less, when the total amount of the photosensitive resin composition layer (b) is 100% by mass.

[0053] <Liquid diene> The photosensitive resin composition layer (b) preferably contains a liquid diene. A liquid diene is a compound having a liquid carbon-carbon double bond. Hereinafter, "liquid" in "liquid diene" means a property that allows it to easily flow and deform, and solidify into the deformed shape upon cooling. A liquid diene has elastomeric properties that allow it to deform instantaneously in response to an external force when that force is applied, and to recover its original shape in a short time when that force is removed.

[0054] The liquid diene is not particularly limited, but examples include liquid polybutadiene, liquid polyisoprene, modified liquid polybutadiene, modified liquid polyisoprene, liquid acrylonitrile-butadiene copolymer, and liquid styrene-butadiene copolymer. The liquid diene is defined as a copolymer in which the diene component accounts for 50% by mass or more.

[0055] Among these, liquid polybutadiene is preferred as the liquid diene from the viewpoint of the mechanical properties of the constituent and the flexographic printing plate using it.

[0056] Furthermore, the amount of 1,2-vinyl bonded liquid diene, preferably liquid polybutadiene, is preferably 1% to 80%, more preferably 5% to 70%, and even more preferably 5% to 65%, from the viewpoint of ensuring appropriate hardness for the constituent and the flexographic printing plate using it.

[0057] Here, "1,2-vinyl bond amount" refers to the proportion of conjugated diene monomers that are incorporated via 1,2-bonds, 3,4-bonds, and 1,4-bonds, among these conjugated diene monomers. The 1,2-vinyl bond amount is calculated for liquid polybutadiene. 1 It can be determined from the peak ratio of 1H-NMR (magnetic resonance spectroscopy).

[0058] Furthermore, 1,2-polybutadiene, which is a liquid polybutadiene having a 1,2-vinyl bond, is preferred from the viewpoint of increasing the hardness of the photosensitive resin composition layer (b) because the vinyl double bond acts as a side chain, resulting in high reactivity in radical polymerization.

[0059] Furthermore, liquid polybutadiene is usually a mixture of 1,2-polybutadiene having 1,2-vinyl bonds and 1,4-polybutadiene having 1,4-vinyl bonds. However, to improve the flexibility of this construct and the flexographic printing plates using it, it is effective to include 1,4-polybutadiene in the liquid diene. There are two types of 1,4-polybutadiene: cis-type 1,4-polybutadiene and trans-type 1,4-polybutadiene. In both the cis and trans forms, 1,4-polybutadiene has a vinyl group, which is a double bond, inside, resulting in low reactivity in radical polymerization and the formation of a flexible resin.

[0060] When using a mixture of liquid polybutadienes having multiple different amounts of 1,2-vinyl bonds, the average value shall be used as the amount of 1,2-vinyl bonds.

[0061] From the viewpoint of easily adjusting the reactivity of the photosensitive resin composition layer (b), it is preferable to mix liquid polybutadiene with a 1,2-vinyl bond content of 10% or less with liquid polybutadiene with a 1,2-vinyl bond content of 80% or more to adjust the overall 1,2-vinyl bond content. More preferably, it is preferable to mix liquid polybutadiene with a 1,2-vinyl bond content of 5% or less with liquid polybutadiene with a 1,2-vinyl bond content of 80% or more to adjust the overall 1,2-vinyl bond content.

[0062] Furthermore, the number-average molecular weight of the liquid diene is not particularly limited as long as it is liquid at 20°C, but from the viewpoint of print resistance and handling of the flexographic printing plate obtained using this composition, it is preferably 500 to 60,000, more preferably 500 to 50,000, and even more preferably 800 to 50,000.

[0063] From the viewpoint of print durability of the present construct and the flexographic printing plate using it, the liquid diene content in the photosensitive resin composition layer (b) is preferably 10% to 40% by mass, more preferably 15% to 40% by mass, and even more preferably 20% to 40% by mass, when the total amount of the photosensitive resin composition layer (b) is 100% by mass.

[0064] <Auxiliary additive ingredients> While there are no particular limitations on auxiliary additives, examples include polar group-containing polymers, plasticizers other than liquid dienes, thermal polymerization inhibitors other than stabilizers, antioxidants, UV absorbers, dyes, and pigments.

[0065] The polar group-containing polymer is not particularly limited, but examples include water-soluble or water-dispersible copolymers having polar groups such as hydrophilic groups like carboxyl groups, amino groups, hydroxyl groups, phosphate groups, sulfonic acid groups, and salts thereof. More specifically, examples include carboxyl group-containing acrylonitrile-butadiene rubber, carboxyl group-containing styrene-butadiene rubber, polymers of aliphatic conjugated dienes containing carboxyl groups, emulsion polymers of ethylenically unsaturated compounds having phosphate groups or carboxyl groups, sulfonic acid group-containing polyurethane, and carboxyl group-containing butadiene latex. These polar group-containing polymers may be used individually or in combination of two or more.

[0066] Among these, carboxyl group-containing butadiene latex is preferred as the polar group-containing polymer from the viewpoint of obtaining high resolution in flexographic printing plates using this structure.

[0067] Other plasticizers besides liquid dienes are not particularly limited, but examples include hydrocarbon oils such as naphthenic oil and paraffin oil; conjugated diene rubbers mainly composed of 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 sebacate esters and phthalate esters. These other plasticizers may have hydroxyl groups or carboxyl groups. Furthermore, these other plasticizers may be conjugated with photopolymerizable reactive groups such as (meth)acryloyl groups. These other plasticizers may be used individually or in combination of two or more.

[0068] As thermal polymerization inhibitors and antioxidants, those commonly used in the field of resin materials or rubber materials can be used. Specifically, phenolic materials are examples.

[0069] Such phenolic materials are not particularly limited, but examples include 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, and 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate. The thermal polymerization inhibitor and antioxidant may be used individually or in combination of two or more.

[0070] While there are no particular limitations on the UV absorbers, examples include known benzophenone compounds, salicylate compounds, acrylonitrile compounds, metal complex salt compounds, and hindered amine compounds. Dyes and pigments listed below may also be used as UV absorbers.

[0071] Such UV absorbers are not particularly limited, but examples include 2-ethoxy-2'-ethyloxalic acid bisanilide and 2,2'-dihydroxy-4-methoxybenzophenone.

[0072] Dyes and pigments are effective means of coloring to improve visibility.

[0073] The dyes are not particularly limited, but examples include water-soluble basic dyes, acid dyes, direct dyes, etc., and water-insoluble sulfur dyes, oil-soluble dyes, disperse dyes, etc. Anthraquinone dyes, indigoid dyes, and azo dyes are particularly preferred, and azo oil-soluble dyes are more preferred.

[0074] There are no particular restrictions on the pigments used, but examples include 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.

[0075] The total amount of the above-mentioned auxiliary additives is preferably 0% to 10% by mass, more preferably 0% to 5% by mass, and even more preferably 0% to 3% by mass, when the total amount of the photosensitive resin composition layer (b) is considered as 100% by mass.

[0076] (Infrared ablation layer (c)) This structure has an infrared ablation layer (c) laminated on top of the photosensitive resin composition layer (b) described above. The infrared ablation layer (c) contains a predetermined resin, is removable with an infrared laser, and functions as a light shielding layer for light other than infrared rays.

[0077] To process the infrared ablation layer (c) with high precision, it is necessary to improve the sensitivity of the infrared ablation layer (c) to the laser. Here, "sensitivity to the laser" means that when drawn with the same laser energy, the volume ablated, especially in the depth direction, is greater.

[0078] As a result of their investigation, the inventors found that in order to improve the laser sensitivity of the infrared ablation layer (c), it is important that the resin contained in the infrared ablation layer is easily depolymerized. "Depolymerization" is the reverse reaction of polymerization, in which a polymer is broken down into monomers.

[0079] When infrared irradiation is performed, the infrared ablation layer instantly reaches temperatures of several hundred degrees Celsius. If the resin is easily depolymerized, even short-duration ablation efficiently decomposes the main chain, causing a rapid decrease in molecular weight and removal from the infrared ablation layer. On the other hand, with resins that are difficult to depolymerize, such as those with polar groups in their side chains, only the side chains decompose during ablation, and the main chain is not severed. Therefore, the resin remains in the infrared ablation layer even after infrared irradiation. Resins obtained by condensation polymerization are known to form a ring structure during decomposition, followed by severance of the main chain. This makes it difficult for the molecular weight to decrease during short-duration infrared ablation, resulting in poor laser sensitivity.

[0080] Based on these mechanisms, it is important that the infrared ablation layer (c) contains a resin that is easily depolymerized. Generally, it is known that the cleavage of the main chain tends to start from thermally unstable parts present in the polymer, such as branching. However, as mentioned above, if the side chains corresponding to the branching are polar, the decomposition of the side chains tends to occur predominantly, making it difficult for the main chain to be cleaved, which is undesirable.

[0081] Therefore, it is important that the side chains of the resin contained in the infrared ablation layer (c) are nonpolar groups. Furthermore, the contribution of intramolecular or intermolecular chain transfer cannot be ignored when main chain cleavage proceeds. For this reason, it is preferable that the resin does not have tertiary hydrogens that are easily extracted by chain transfer. In other words, it is preferable that the parts corresponding to the symmetry plane of branching are also nonpolar groups.

[0082] (resin) The resin contained in the infrared ablation layer (c) of this embodiment has a constituent unit (c1) containing a quaternary carbon atom to which two nonpolar groups are bonded, as represented by the following general formula (1), and may have other constituent units as needed. [ka] (Here, in formula (1), R1 and R2 each independently represent a nonpolar group, and R3 and R4 each independently represent a hydrogen atom or a nonpolar group.)

[0083] In this embodiment, "monomer" refers to the compound before polymerization, and "constituent unit" refers to a predetermined repeating unit formed by the polymerization of monomers.

[0084] The nonpolar group in the above general formula (1) is not particularly limited as long as it is composed of a carbon atom and / or a silicon atom and a hydrogen atom, but examples include alkyl groups, aryl groups, cycloalkyl groups, phenyl groups, alkenyl groups, aralkyl groups, cycloalkenyl groups, alkynyl groups, silyl groups, siloxanyl groups, etc. Note that nonpolar groups do not contain hydrogen atoms.

[0085] Among these, from the viewpoint of the laser sensitivity of the infrared ablation layer (c), alkyl groups and phenyl groups are preferred for the groups represented by R1, R2, R3, and R4. More preferably, the groups represented by R1 and R2 are alkyl groups and phenyl groups, and the nonpolar groups of R3 and R4 are alkyl groups and phenyl groups, or the groups represented by R1 and R2 are alkyl groups and phenyl groups, and R3 and R4 are hydrogen atoms. This tends to improve depolymerization and thus enhance laser sensitivity.

[0086] Furthermore, from the perspective of laser sensitivity, the groups represented by R1 include alkyl groups and phenyl groups. The base preferable.

[0087] The number of carbon atoms in the above nonpolar group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 5.

[0088] Monomers satisfying general formula (1) are not particularly limited, but examples include isobutylene, 2-methyl-2-butene, 2,3-dimethyl-2-butene, and those in which the methyl group is substituted with other alkyl groups such as ethyl groups, and their modified products; α-methylstyrene, cis-(1-methyl-1-propenyl)benzene, trans-(1-methyl-1-propenyl)benzene, and those in which the methyl group is substituted with other alkyl groups such as ethyl groups, and their modified products; and 1,1-diphenylethylene.

[0089] In general formula (1), R3 and R4 are preferably a hydrogen atom, an alkyl group, an aryl group, a cycloalkyl group, a phenyl group, an alkenyl group, an aralkyl group, a cycloalkenyl group, an alkynyl group, a silyl group, or a siloxanyl group, and more preferably both are hydrogen atoms. This improves the depolymerization properties of the resin, and therefore tends to improve the laser sensitivity of the infrared ablation layer (c).

[0090] Examples of materials that satisfy this configuration include isobutylene, α-methylstyrene, and those in which the methyl groups of these materials are replaced with other alkyl groups such as ethyl groups. Furthermore, using monomers having phenyl groups, such as α-methylstyrene, tends to further improve the pinhole resistance of the infrared ablation layer (c).

[0091] Furthermore, in general formula (1), R1 and R2 are preferably, independently, an alkyl group, an aryl group, a cycloalkyl group, a phenyl group, an alkenyl group, an aralkyl group, a cycloalkenyl group, an alkynyl group, a silyl group, or a siloxanyl group, more preferably an alkyl group or a phenyl group, and even more preferably an alkyl group, independently of each other. The presence of alkyl groups in R1 and / or R2 allows for rubber-like elasticity. Therefore, it can form the soft portion of the elastomer, and the flexibility of the infrared ablation layer (c) tends to be further improved. Additionally, the presence of phenyl groups in R1 and / or R2 tends to allow for smooth molding of the structure at relatively low temperatures.

[0092] Furthermore, the constituent unit (c1) may be used alone or in combination of two or more types. For example, the above resin may have a constituent unit (c1) in which R1 and R2 are alkyl groups, and a constituent unit in which one of R1 and R2 is an alkyl group and the other is a phenyl group. This makes it possible to improve the properties of both alkyl groups and phenyl groups.

[0093] Examples of materials that satisfy this configuration include isobutylene and isobutylene in which the methyl groups are substituted with other alkyl groups such as ethyl groups.

[0094] Furthermore, the content of the constituent unit (c1) is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more, relative to the total amount of resin. Furthermore, the content of the constituent unit (c1) is preferably 100% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less, even more preferably 85% by mass or less, and even more preferably 80% by mass or less, relative to the total amount of resin. The upper and lower limits of these values ​​can be combined arbitrarily.

[0095] When the content of constituent unit (c1) is 40% by mass or more, the laser sensitivity and flexibility of the infrared ablation layer (c) tend to be further improved. Conversely, when the content of constituent unit (c1) is 100% by mass or less, the pinhole resistance of the infrared ablation layer (c) tend to be further improved.

[0096] The resin used in the infrared ablation layer (c) preferably contains, in addition to the constituent unit (c1), a constituent unit (c2) having an aromatic group in its side chain. The constituent unit (c2) is preferably derived from a monovinyl-substituted aromatic hydrocarbon. The monovinyl aromatic hydrocarbon may be chemically bonded to a monomer represented by general formula (1), or added as a separate resin; however, from the viewpoint of dispersibility and the resulting uniformity of laser processing, it is preferable that it be chemically bonded to form a copolymer. The inclusion of a constituent unit (c2) derived from a monovinyl-substituted aromatic hydrocarbon in the resin tends to further improve pinhole resistance.

[0097] The monovinyl aromatic hydrocarbon compound is not particularly limited, but examples include monomers such as styrene, t-butylstyrene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene, vinylpyridine, p-methylstyrene, and tertiary butylstyrene. Among these, styrene is preferred because the constituent can be molded smoothly at relatively low temperatures. The constituent unit (c2) may be a single type or a combination of two or more types.

[0098] The content of constituent unit (c2) is preferably 0% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, even more preferably 15% by mass or more, and even more preferably 20% by mass or more, relative to the total amount of resin. Furthermore, the content of constituent unit (c2) is preferably 60% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less, even more preferably 45% by mass or less, and even more preferably 40% by mass or less, relative to the total amount of resin. The upper and lower limits of these values ​​can be arbitrarily combined.

[0099] When the content of the constituent unit (c2) is 0% by mass or more, the pinhole resistance of the infrared ablation layer (c) tends to improve. Furthermore, when the content of the constituent unit (c2) is 60% by mass or less, the laser sensitivity and flexibility of the infrared ablation layer (c) tend to improve. Note that "0% by mass or more" includes both embodiments containing the constituent unit (c2) and embodiments not containing it. These upper and lower limits can be combined arbitrarily.

[0100] The content and ratio of constituent units (c1) and (c2), etc., in the above resin used in the infrared ablation layer (c) are determined by a nuclear magnetic resonance apparatus ( 1 It can be measured using 1H-NMR.

[0101] The infrared ablation layer (c) may contain other resins in addition to the resin described above. In this case, the content of the resin is preferably 50% by mass or more, and more preferably 70% by mass or more and 100% by mass or less, relative to the total resin components of the infrared ablation layer (c). When the resin content is within the above range, the laser sensitivity and flexibility of the infrared ablation layer (c) tend to be further improved. Furthermore, when a resin having polar groups in its side chain is used as the other resin, it is preferable that the resin be contained in 70% or more of the total resin components from the viewpoint of laser sensitivity.

[0102] The resin content is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, relative to the total amount of the infrared ablation layer (c). Furthermore, the resin content is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, relative to the total amount of the infrared ablation layer (c). These upper and lower limits can be combined arbitrarily.

[0103] When the resin content is 20% by mass or more, the pinhole resistance and flexibility of the infrared ablation layer (c) tend to improve. Conversely, when the resin content is 90% by mass or less, the laser sensitivity and shielding properties of the infrared ablation layer (c) tend to improve.

[0104] (Infrared absorbing material) The infrared ablation layer (c) may contain an infrared absorbing material for ablation processing. Typically, the infrared absorbing material used is an element or compound that has strong absorption in the range of 750 to 2000 nm.

[0105] Such infrared absorbing materials are not particularly limited, but examples include inorganic pigments such as carbon black, graphite, copper chromate, and chromium oxide; and dyes such as polyphthalocyanine compounds, cyanine dyes, and metal thiolate dyes. The smaller the particle size, the higher the sensitivity to infrared lasers, but carbon black is particularly preferable as an infrared absorbing material because it can be used in a wide particle size range from 13 nm to 85 nm. Carbon black can also function as a shielding material as described below. These infrared absorbing materials are added in a range that provides sensitivity that allows them to be cut by the laser beam used.

[0106] (shielding substance) The infrared ablation layer (c) may contain a shielding material against non-infrared rays such as ultraviolet rays, as it serves as a mask. The non-infrared shielding material can be a substance that reflects or absorbs ultraviolet light. Examples include ultraviolet absorbers, carbon black, and graphite.

[0107] The total content of infrared absorbing material and shielding material is preferably 10% to 80% by mass, preferably 20% to 70% by mass, and preferably 30% to 60% by mass, relative to the total amount of the infrared ablation layer (c). When the total content of infrared absorbing material and shielding material is within the above range, laser sensitivity and shielding performance tend to be further improved.

[0108] (film thickness) The thickness of the infrared ablation layer (c) of this structure should be thicker from the viewpoint of ensuring shielding against ultraviolet light during the exposure process of this structure, and thinner from the viewpoint of improving ablation performance.

[0109] From the above viewpoint, the thickness of the infrared ablation layer (c) is preferably 0.1 μm or more and 20 μm or less, more preferably 0.5 μm or more and 15 μm or less, and even more preferably 1.0 μm or more and 10 μm or less.

[0110] For the non-infrared shielding effect of the infrared ablation layer (c), it is preferable that the optical density of the infrared ablation layer (c) be 2 or higher, and more preferably 3 or higher.

[0111] Optical density can be measured using a D200-II transmission densitometer (manufactured by GretagMacbeth). Furthermore, optical density is measured in the so-called visual range (ISO visual), and the light being measured has a wavelength range of approximately 400-750 nm.

[0112] The method for forming the infrared ablation layer (c) is not particularly limited, but for example, when carbon black is used as both an infrared absorbing material and a non-infrared shielding material, first a resin solution is prepared using a predetermined solvent, carbon black and a dispersant are added thereto, the carbon black is dispersed in the resin solution and then coated onto a cover film (f) having a peel force adjusting layer (d) described later, and then this cover film (f) is laminated or pressed onto a photosensitive resin composition layer (b) to transfer a non-infrared shielding layer that can be cut with an infrared laser.

[0113] Effective methods for dispersing carbon black in a resin solution include a combination of forced stirring with a stirring blade and stirring using ultrasound or various mills. Alternatively, pre-mixing the resin, carbon black, and dispersant using an extruder or kneader before dissolving them in a solvent is also effective in obtaining good dispersibility of carbon black. Furthermore, carbon black may be forcibly dispersed in a resin that is in the state of a latex solution.

[0114] The solvent, such as a solution or dispersion, used to form the infrared ablation layer (c) can be appropriately selected considering the solubility of the resin and infrared absorber used. A single solvent may be used, or a mixture of two or more solvents may be used.

[0115] Furthermore, it is also effective to improve the film quality of the infrared ablation layer (c) by, for example, mixing a solvent with a relatively low boiling point with a solvent with a high boiling point and controlling the evaporation rate of the solvents.

[0116] The solvent for forming the infrared ablation layer (c) is not particularly limited, but examples include toluene, xylene, cyclohexane, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, amyl acetate, methyl ethyl ketone, acetone, cyclohexanone, ethylene glycol, propylene glycol, ethanol, water, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, dimethylacetamide, dimethylformamide, n-propyl alcohol, i-propyl alcohol, 1,4-dioxane, tetrahydrofuran, diethyl ether, n-hexane, n-heptane, n-pentane, acetonitrile and its analogs.

[0117] (Peeling force adjustment layer (d)) By enabling high-resolution drawing of the infrared ablation layer (c), when a cover film (f) made of polyethylene terephthalate film is placed in contact with the infrared ablation layer, peeling off the cover film (f) becomes difficult. This is presumed to be because the structure represented by the general formula (1) described above interacts with the ester bond portion contained in polyethylene terephthalate, increasing the adhesion force.

[0118] As a result of our investigation, we found that a peeling force adjusting layer (d) having a specific composition is important for improving peeling force.

[0119] Specifically, in analysis of the peeling force adjustment layer by time-of-flight secondary ion mass spectrometry (TOF-SIMS), it is important that the intensity of C2N3 (m / z=66) is between 0.30 and 7.00, when the intensity of C2H (m / z=25) for negative ions is set to 1 and the intensity of C2H3 (m / z=27) for positive ions is set to 1. C2N3 is a peak derived from the melamine structure, and it significantly reduces the peeling force. This is presumed to be because the presence of the melamine structure causes electrostatic repulsion with the resin components contained in the ablation layer (c). If the intensity of C2N3 (m / z=66) is less than 0.30, a sufficient improvement in peeling force is not obtained, and if it is greater than 7.00, adhesion to the cover film is not obtained. From the viewpoint of peeling force and adhesion to the cover film, the intensity of C2N3 (m / z=66) is preferably between 0.35 and 6.90, and more preferably between 0.45 and 6.80.

[0120] The strength of C2N3 (m / z=66) can be controlled by changing the amount of melamine resin used when manufacturing the peel force adjustment layer (d), which will be described later.

[0121] Furthermore, it is important that the intensity of C6H5 (m / z=77) is between 0.05 and 0.40. The C6H5 peak is derived from the benzene ring. The presence of the benzene ring strengthens the interaction with the resin contained in the infrared ablation layer (c), worsening the peeling force. Therefore, it is important that the intensity is within the above range, preferably between 0.05 and 0.35, and more preferably between 0.05 and 0.30.

[0122] The strength of C6H5 (m / z=77) can be controlled by changing the type and amount of alkyd resin used when manufacturing the peel force adjustment layer (d), which will be described later.

[0123] Furthermore, it is preferable that the intensity of C3H5 (m / z=41) is between 3.00 and 16.00. C3H5 is a peak derived from long-chain alkyl groups, and having such a structure reduces interaction with the resin contained in the infrared ablation layer (c), thereby improving the peeling force. For this reason, it is preferable that the intensity is within the above range, more preferably between 3.10 and 16.00, and even more preferably between 3.20 and 16.00.

[0124] The strength of C3H5 (m / z=41) can be controlled by changing the type and amount of alkyd resin used when manufacturing the peel force adjustment layer (d) described later.

[0125] To impart a melamine structure, i.e., C2N3 (m / z=66), to the peel force adjusting layer (d), a melamine resin can be used, and among these, methyl etherified melamine resin is preferred. This makes it possible to obtain a peel force adjusting layer (d) within the above numerical range.

[0126] Examples of methyl etherified melamine resins that can be used include MW-30M, MW-30, MW-22, MS-11, MS-001, MX-730, MX-750, MX-706, and MX-035 manufactured by Sanwa Chemical Co., Ltd.

[0127] Alkyd resins can be used to impart C6H5 (m / z=77) and C3H5 (m / z=41). Alkyd resins are resins produced by the condensation reaction of oils, fatty acids, acids, and alcohols. Among these, grades containing a large amount of oil or fatty acids are preferred in order to make C6H5 smaller and C3H5 larger.

[0128] Examples of such resins include Arakid 8012, 5350, and 1465-60 manufactured by Arakawa Chemical Industries.

[0129] To satisfy the above numerical range, the ratio of melamine resin to alkyd resin is preferably melamine resin / alkyd resin = 95 / 5 to 99 / 1, and more preferably 96 / 4 to 99 / 1.

[0130] The total content of melamine resin and alkyd resin is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, relative to the total amount of the peel force adjusting layer (d). Furthermore, the total content of melamine resin and alkyd resin is preferably 100% by mass or less, more preferably 98% by mass or less, and even more preferably 98% by mass or less, relative to the total amount of the peel force adjusting layer (d). The upper and lower limits of these values ​​can be arbitrarily combined.

[0131] The method for forming the peel force adjusting layer (d) is not particularly limited, but it is possible to form the film by mixing melamine resin, alkyd resin and catalyst, coating it onto the cover film (f) using methods such as gravure coating, Meyer bar coating, air knife coating, or doctor knife coating, and then heating the cover film (f) to crosslink the resin and make it adhere to the cover film (f).

[0132] The cover film (f) for forming the peel force adjustment layer (d) of this structure is preferably a film that has excellent dimensional stability even when heated, for example, polyethylene terephthalate film is preferred.

[0133] (middle layer(e)) The structure may further have one or more intermediate layers (e) between the photosensitive resin composition layer (b) and the infrared ablation layer (c). The intermediate layer (e) is not particularly limited, but can be, for example, an oxygen-inhibiting layer, an adhesive layer, and / or a protective layer. Each layer will be described below.

[0134] In order to produce high-resolution printed materials with highlight areas, it is necessary to form minute dots on the flexographic printing plate. From the viewpoint of forming such minute dots, the intermediate layer (e) is preferably an oxygen-inhibiting layer having oxygen-inhibiting properties.

[0135] When the photosensitive resin composition layer (b) is cured by irradiation with ultraviolet light, curing proceeds by radical polymerization. If oxygen is present during this radical polymerization, the radical generating compound reacts with the oxygen, suppressing the polymerization reaction. When the polymerization reaction is suppressed in this way, there is a risk that unreacted portions will remain in the exposed areas of the photosensitive resin composition layer (b). These unreacted portions are removed in the fourth step described later, so the pattern ultimately formed on the flexographic printing plate will have a curved shape at the tip. This is because the portion of the photosensitive resin composition layer (b) on the infrared ablation layer (c) side is particularly susceptible to polymerization inhibition by oxygen, and unreacted portions are likely to occur in the photosensitive resin composition layer (b) directly beneath the infrared ablation layer (c).

[0136] In contrast, reducing the amount of oxygen present during UV curing makes it more difficult to suppress the polymerization reaction, resulting in a pattern with a flat tip. Therefore, when attempting to create a pattern with a flat tip, it is effective to reduce the amount of oxygen in contact with the photosensitive resin composition layer (b) by having an oxygen-inhibiting intermediate layer (e).

[0137] Furthermore, the intermediate layer (e) may be an adhesive layer that improves the adhesion between the photosensitive resin composition layer (b) and the infrared ablation layer (c). This tends to further improve handling.

[0138] Furthermore, the intermediate layer (e) may also have the function of protecting the infrared ablation layer (c). In the conventional manufacturing process of flexographic printing plates, when the infrared ablation layer (c) laminated with the cover film (f) is fed through the film, the infrared ablation layer (c) may come into contact with the roll or become compressed during film roll transport, causing friction between the infrared ablation layer (c) and the cover film (f) laminated to it within the roll. This can cause the infrared ablation layer (c) to physically break off, potentially resulting in pinholes. In addition, when the photosensitive resin composition layer (b) and the infrared ablation layer (c) are laminated by a method in which the photosensitive resin composition layer (b) is applied to the infrared ablation layer (c) while extruding the photosensitive resin composition layer (b), friction generated when the heated and melted photosensitive resin composition flows over the infrared ablation layer (c) may cause pinholes.

[0139] To prevent the occurrence of pinholes in such infrared ablation layer (c), it is preferable that the intermediate layer (e) constituting this structure has physical strength and heat resistance as a protective layer.

[0140] [Method for manufacturing flexographic printing plates] The method for manufacturing a flexographic printing plate according to this embodiment includes, using the present structure, a first step of irradiating ultraviolet light from the support (a) side; a second step of irradiating the infrared ablation layer (c) with infrared light to draw a pattern; a third step of using the infrared ablation layer (c) on which the pattern has been drawn as a mask to irradiate the photosensitive resin composition layer (b) with ultraviolet light to expose the pattern; and a fourth step of removing the unexposed portions of the infrared ablation layer (c) and the photosensitive resin composition layer (b).

[0141] Subsequently, a post-exposure treatment is performed as needed to obtain a flexographic printing plate (relief printing plate) made of a cured photosensitive resin composition layer. Furthermore, from the viewpoint of imparting release properties, the surface of the flexographic printing plate may be brought into contact with a liquid containing a silicone compound and / or a fluorine compound.

[0142] Figure 2 shows a schematic diagram illustrating a method for manufacturing a flexographic printing plate using the photosensitive resin structure for flexographic printing plates according to this embodiment. Each step will be described in detail below.

[0143] (First step) In the first step, the method of irradiating the photosensitive resin composition layer (b) with ultraviolet light from the support (a) side is not particularly limited and can be carried out using a known irradiation unit. The wavelength of the ultraviolet light irradiated at this time is preferably 150 to 500 nm, and more preferably 300 to 400 nm.

[0144] There are no particular restrictions on the ultraviolet light source, but for example, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, zirconium lamps, carbon arc lamps, ultraviolet fluorescent lamps, etc. can be used.

[0145] This first step may be performed either before or after the second step, which will be described later.

[0146] (Second step) In the second step, the method for irradiating the infrared ablation layer (c) with infrared light to create a pattern is not particularly limited and can be carried out using a known irradiation unit. In addition, the irradiation of the infrared ablation layer (c) with infrared light can be performed from the infrared ablation layer (c) side.

[0147] Since this structure has a cover film (f), the cover film (f) is first peeled off together with the peel force adjustment layer (d) before infrared irradiation. Then, the infrared ablation layer (c) is pattern-irradiated with infrared light to decompose the resin in the infrared irradiation area and draw a pattern. This makes it possible to form a mask of the infrared ablation layer (c) on the photosensitive resin composition layer (b).

[0148] In the second step, suitable infrared lasers include, for example, an ND / YAG laser (e.g., 1064 nm) or a diode laser (e.g., 830 nm). Laser systems suitable for CTP platemaking technology are commercially available, and for example, the diode laser system CDI Spark (ESKO GRAPHICS) can be used. This laser system includes a rotating cylindrical drum that holds the assembly, an IR laser irradiation device, and a layout computer, and image information is transmitted directly from the layout computer to the laser device.

[0149] (Third step) The third step involves irradiating the photosensitive resin composition layer (b) with ultraviolet light, using the patterned infrared ablation layer (c) as a mask, to expose the pattern. At this time, the light passing through the mask accelerates the curing reaction of the photosensitive resin composition layer (b), and the pattern formed on the infrared ablation layer (c) is transferred to the photosensitive resin composition layer (b) with the relief inverted. The ultraviolet light may be irradiated over the entire surface of the structure.

[0150] The third step can be performed with the component attached to the laser cylinder, but generally, the component is removed from the laser device and irradiated using a conventional irradiation unit. The irradiation unit can be the same as the one exemplified in the ultraviolet irradiation in the first step.

[0151] (Fourth step) The fourth step is to remove the unexposed portions of the infrared ablation layer (b) and the photosensitive resin composition layer (c). The removal method in the fourth step (developing step) is not particularly limited, and conventionally known methods can be applied.

[0152] Specifically, as described above, the photosensitive resin composition layer (b) of the structure is exposed to light, and then the unexposed portion is washed away with a solvent for solvent development or a cleaning solution for water development, or the unexposed portion heated to 40°C to 200°C is brought into contact with a predetermined absorbent layer and the absorbent layer is removed to remove the unexposed portion.

[0153] Subsequently, the flexographic printing plate is manufactured by performing post-exposure treatment as needed.

[0154] If an intermediate layer (e) is present between the infrared ablation layer (c) and the photosensitive resin composition layer (b), it may be removed simultaneously during the developing process.

[0155] The developing solvent used to develop the unexposed areas is not particularly limited, but examples include esters such as heptyl acetate and 3-methoxybutyl acetate; hydrocarbons such as petroleum fractions, toluene, and decalin; and mixtures of chlorinated organic solvents such as tetrachloroethylene with alcohols such as propanol, butanol, and pentanol. The unexposed areas are washed out by spraying from a nozzle or by brushing with a brush.

[0156] Furthermore, water, alkaline aqueous solutions, neutral detergents, and surfactants can be suitably used as cleaning solutions for water-based developing.

[0157] Examples of surfactants include anionic surfactants, amphoteric surfactants, and nonionic surfactants. These may be used individually or in combination of two or more types.

[0158] Anionic surfactants are not particularly limited, but examples include sulfate esters, higher alcohol sulfates, higher alkyl ether sulfates, sulfated olefins, alkylbenzene sulfons, α-olefin sulfons, phosphate esters, and dithiophosphate esters.

[0159] The amphoteric surfactant is not particularly limited, but examples include amino acid-type amphoteric surfactants and betaine-type amphoteric surfactants.

[0160] Nonionic surfactants are not particularly limited, but examples include polyethylene glycol-type surfactants such as higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene oxide adducts, higher alkylamine ethylene oxide adducts, fatty acid amide ethylene oxide adducts, and polypropylene glycol ethylene oxide adducts, as well as polyhydric alcohol-type surfactants such as glycerol fatty acid esters, pentaerythritol fatty acid esters, sorbitol and sorbitan fatty acid esters, alkyl esters of polyhydric alcohols, and fatty acid amides of alkanolamines.

[0161] Furthermore, a pH adjusting agent may be used in the alkaline aqueous solution. The pH adjusting agent can be either an organic or inorganic material, but one that can adjust the pH to 9 or higher is preferred. There are no particular limitations on the pH adjusting agent, but examples include sodium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, sodium metasilicate, and sodium succinate.

[0162] The absorbent layer capable of absorbing the unexposed portion is not particularly limited, but examples include nonwoven fabrics, paper materials, textile fabrics, open-cell foams, and porous materials. Among these, nonwoven fabrics made of nylon, polyester, polypropylene, and polyethylene, and combinations thereof, are preferred, and continuous nonwoven webs of nylon or polyester are more preferred.

[0163] [Flexographic printing method] The flexographic printing method of this embodiment comprises: a first step of irradiating ultraviolet light from the support (a) side using the above-mentioned photosensitive resin structure for flexographic printing plates; a second step of irradiating the infrared ablation layer (c) with infrared light to draw a pattern; a third step of using the infrared ablation layer (c) on which the pattern has been drawn as a mask to irradiate the photosensitive resin composition layer (b) with ultraviolet light to expose the pattern; a fourth step of removing the unexposed parts of the infrared ablation layer (c) and the photosensitive resin composition layer (b) to manufacture a flexographic printing plate; and a fifth step of printing using the flexographic printing plate.

[0164] The first to fourth steps in the flexographic printing method are as described above.

[0165] (Fifth step) The fifth step is to print using the flexographic printing plate obtained in the first to fourth steps. The printing method using the flexographic printing plate is not particularly limited, as long as it involves applying ink to the raised parts of the flexographic printing plate and transferring that ink to the substrate. [Examples]

[0166] The present invention will be described in more detail below with reference to specific examples and comparative examples, but the present invention is not limited in any way by the following examples.

[0167] [TOF-SIMS measurement] The cover film (f) with the peel force adjustment layer (d) applied, or the cover film (f) from the photosensitive resin structure for flexographic printing plates, was peeled off and cut to an appropriate size, and the surface with the peel force adjustment layer (d) was measured under the following conditions.

[0168] Measurement device: nano-TOF (manufactured by ULVAC-PHI) Primary ion: Bi3 ++ Acceleration voltage: 30kV Current value: Approximately 0.1nA (as DC) Analysis area: 200μm x 200μm Total time: 5 min Detected ions: positive and negative ions Neutralizing electron gun: Yes, positive ions are produced using Ar monomer in combination.

[0169] The intensity of C2H (m / z=25) was normalized to 1 for negative ions, and the intensity of C2H3 (m / z=27) was normalized to 1 for positive ions. The relative intensities of C2N3 (m / z=66), C6H5 (m / z=77), and C3H5 (m / z=41) were then determined. Here, peaks were detected on the negative ion side for C2N3 (m / z=66), and on the positive ion side for C6H5 (m / z=77) and C3H5 (m / z=41).

[0170] [Manufacturing of photosensitive resin components for flexographic printing plates] In the following examples and comparative examples, photosensitive resin components for flexographic printing plates were manufactured.

[0171] ((1) Manufacturing of a laminate of a support and a photosensitive resin composition layer) A photosensitive resin composition was prepared by kneading 60 parts by mass of styrene-butadiene-styrene block copolymer (manufactured by Asahi Kasei, trade name: Toughprene A), 30 parts by mass of liquid polybutadiene (manufactured by Nippon Petrochemical, trade name: B-2000), 7 parts by mass of 1,9-nonanediol diacrylate, 2 parts by mass of 2,2-dimethoxy-2-phenylacetophenone, and 0.3 parts by mass of 2,6-di-t-butyl-p-cresol in a pressure kneader.

[0172] Next, the photosensitive resin composition was fed into an extrusion molding machine, and a base film (support) was bonded to one side of the photosensitive resin composition extruded from a T-type die. A release film (manufactured by Mitsubishi Chemical Corporation, product name: Diafoil MRV100) was then bonded to the side of the photosensitive resin composition layer opposite to the support lamination side to obtain a laminate of the support and the photosensitive resin composition layer.

[0173] ((2) Manufacturing of laminates with peel force adjustment layer) <Example of manufacturing of peel force adjustment layer laminate 1> • Amino resin (manufactured by Sanwa Chemical, MX-706, non-volatile content 70%): 139 parts by mass • Alkyd resin (Arakawa Chemical Industries, Ltd., Arakid 8012, 50% non-volatile content): 6 parts by mass

[0174] The above materials were mixed, and then 3 parts by mass of p-toluenesulfonic acid were added and mixed further. The mixed liquid is then placed on a 100 μm thick PET film that will serve as a cover film, with a dry weight of 0.1 g / m². 2 The material was coated in such a manner, and then subjected to a heating and drying treatment at 100°C for 2 minutes to obtain a laminate with a peel force adjustment layer 1. Table 1 below shows the constituent materials and physical properties of the peel force adjustment layer laminate 1.

[0175] <Example of manufacturing of peel force adjustment layer laminate 2> A peeling force adjusting layer laminate 2 was obtained in the same manner as peeling force adjusting layer laminate 1, except that Arakid 1465-60 (60% non-volatile content) manufactured by Arakawa Chemical Industries was used as the alkyd resin and the mixing ratio of the amino resin and alkyd resin was changed as shown in Table 1 below. Table 1 below shows the constituent materials and their physical properties.

[0176] <Manufacturing examples of peel force adjustment layer laminates 3-5> Except for changing the types and blending ratios of amino resin and alkyd resin as shown in Table 1 below, peel force adjusting layer laminates 3 to 5 were obtained in the same manner as described above for peel force adjusting layer laminate 1. Table 1 below shows the constituent materials and their physical properties.

[0177] <Example of manufacturing of peel force adjusting layer laminate 6> • Amide resin (DIC, Super Pekkamine ODL-60): 95 parts by mass • Alkyd resin (manufactured by Hitachi Chemical Polymer, Teslac 2052-60): 5 parts by mass • Hardener (paratoluenesulfonic acid): 3 parts by mass

[0178] The above materials were dissolved in a solvent to prepare a release force adjustment layer composition solution. The release force adjustment layer composition solution was applied to a PET film support member (E5000, Toyobo Co., Ltd., thickness: 100 μm) (which functions as a protective film when used as a photosensitive resin relief printing plate) that had been treated with a release agent on both sides, using a bar coater of appropriate size so that the layer thickness would be 1.0 μm. The laminated body 6 of the release force adjustment layer was then heated, dried, and cured at 160°C for 3 minutes. Table 1 below shows the constituent materials and physical properties of the peel force adjustment layer laminate 6.

[0179] [Table 1]

[0180] ((3) Manufacturing of resin used in the infrared ablation layer) <Manufacturing of resin 1> After purging the polymerization vessel in a 2L separable flask with nitrogen, 456.1 mL of n-hexane (dried on molecular sieves) and 656.5 mL of butyl chloride (dried on molecular sieves) were added using a syringe. The polymerization vessel was then cooled by immersing it in a dry ice / methanol bath at -70°C. A Teflon® transfer tube was connected to a pressure-resistant glass liquefaction sampling tube with a three-way stopcock containing 161.1 g (2871 mmol) of isobutylene monomer, and the isobutylene monomer was transferred into the polymerization vessel under nitrogen pressure. 0.647 g (2.8 mmol) of p-dicumyl chloride and 1.22 g (14 mmol) of N,N-dimethylacetamide were added. Next, 8.67 mL (79.1 mmol) of titanium tetrachloride was added to start polymerization. After stirring at the same temperature for 1.5 hours from the start of polymerization, approximately 1 mL of the polymerization solution was withdrawn from the polymerization solution for sampling. Next, a mixed solution of 77.9 g (748 mmol) of styrene monomer, which had been pre-cooled to -70°C, 23.9 mL of n-hexane, and 34.3 mL of butyl chloride was added to the polymerization vessel. Forty-five minutes after adding the mixed solution, approximately 40 mL of methanol was added to terminate the reaction.

[0181] After removing solvents and other substances from the reaction solution by distillation, the solution was dissolved in toluene and washed twice with water. Further, a large amount of methanol was added to the toluene solution to precipitate the polymer, and the resulting polymer was vacuum-dried at 60°C for 24 hours to obtain resin 1. The styrene content was... 1 The concentration was determined to be 30% by mass using 1H-NMR.

[0182] <Manufacturing examples of resins 2 and 3> Resins 2 and 3 were obtained in the same manner as Resin 1, except that the types of monomers used and their mixing ratios were changed as shown in Table 2 below. Table 2 below shows the constituent materials and physical properties of the resins.

[0183] [Table 2]

[0184] ((4) Manufacturing of infrared ablation layer laminates) <Example of manufacturing of infrared ablation layer laminate 1> Resin 1 was dissolved in a solvent by mixing 6.5 parts by mass of resin 1, 54.0 parts by mass of toluene, and 36.0 parts by mass of cyclohexanone. Then, 3.5 parts by mass of carbon black (Mitsubishi Chemical, #1000) was added and mixed in a bead mill for 4 hours to obtain a carbon black dispersion.

[0185] The carbon black dispersion obtained as described above was coated onto the surface of the peel force adjustment layer on the peel force adjustment layer laminate 1 so that the film thickness after drying was 2.5 μm, and a drying treatment was performed at 90°C for 2 minutes to obtain an infrared ablation layer laminate 1, which is a laminate of an infrared ablation layer, a peel force adjustment layer laminate 1, and a cover film.

[0186] <Manufacturing examples of infrared ablation layer laminates 2-11> Infrared ablation layer laminates 2 to 11 were obtained in the same manner as infrared ablation layer laminate 1, except that the resin used and the peel force adjusting layer laminate were changed as shown in Table 3 below.

[0187] [Table 3]

[0188] ((5) Preparation of photosensitive resin components for flexographic printing plates) <Example 1> The release film was peeled off the laminate of the support and the photosensitive resin composition layer, and the infrared ablation layer laminate 1 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. The cover film surface was placed on a hot plate set to 120°C so that it was in contact with the heating part of the hot plate, and heat was applied for 1 minute to obtain the photosensitive resin structure 1 for flexographic printing plates of Example 1.

[0189] The photosensitive resin structure 1 for flexographic printing plates, prepared as described above in Example 1, was evaluated as follows. The evaluation results are shown in Table 4 below. The evaluation was performed by cutting the photosensitive resin structure for flexographic printing plates into pieces measuring 10 cm x 15 cm.

[0190] (Evaluation method) <Evaluation of laser sensitivity> After removing the cover film with a peel force adjustment layer from the photosensitive resin structure for flexographic printing plates, the plate was placed on an Esko CDI SPARK2530, and laser drawing was performed with a test image having an image pattern that formed a total of 2 pixels (2x1 pixels) at a resolution of 8000 dpi and a laser intensity of 3.0 J.

[0191] Subsequently, the ablated area was observed using a laser microscope (VK-X100, manufactured by Keyence Corporation; objective lens 100x), and the length of the infrared ablation layer surface in the long axis direction (2-pixel side) where the laser was abrading, and the length of the interface with the photosensitive resin composition layer were measured. The length of the interface with the photosensitive resin composition layer / infrared ablation layer surface was evaluated as an indicator of laser sensitivity as follows. A value of C or higher was considered acceptable for accurate high-resolution rendering.

[0192] (Evaluation Criteria) A: The hole is through and the interface with the photosensitive resin composition / the length of the infrared ablation layer surface is 0.50 or longer. B: The hole is through and the interface with the photosensitive resin composition / the length of the infrared ablation layer surface is 0.40 or more and less than 0.50. C: The hole is through-hole and the interface with the photosensitive resin composition / the length of the infrared ablation layer surface is 0.30 or more and less than 0.40. D: The hole is through-hole and the interface with the photosensitive resin composition / the length of the infrared ablation layer surface is less than 0.30. E: The hole does not go all the way through.

[0193] <Evaluation of peelability> The photosensitive resin components for flexographic printing plates were stored for one month in a constant temperature and humidity chamber PH-3K (manufactured by ESPEC Corporation) set to a temperature of 32°C and a relative humidity of 80%RH. After that, the peeling force was measured using the method described below.

[0194] The peeling force was measured using a tensile testing machine, Autograph AGS-X100N (manufactured by Shimadzu Corporation), by peeling the cover film in a 180° direction at a crosshead speed of 50 mm / min.

[0195] Based on the results, the following criteria were used to evaluate the results on a scale from 1 to 5. Grades C and above were considered acceptable for use.

[0196] A: The maximum peeling force is 10 gf / 10 cm or more, and less than 30 gf / 10 cm. B: The maximum peeling force is 30 gf / 10 cm or more, and less than 40 gf / 10 cm. C: The maximum peeling force is 40 gf / 10 cm or more, making peeling possible. E: The infrared ablation layer cannot be peeled off, or it is transferred to the cover film. F: The maximum peeling force is less than 10gf / 10cm, so it peels off easily.

[0197] <Pinhole (pH) evaluation> After removing the cover film with the peel force adjustment layer laminated onto the infrared ablation layer laminate 1, the infrared ablation layer was placed on a light table, and the sample was illuminated from below with the light table. Areas that appeared to glow were determined to be pinholes.

[0198] In the infrared ablation layer, the number of pinholes with a major axis of 20 μm or larger was counted, and the average value was calculated (pinholes / m²). 2 The values ​​of ) were calculated and evaluated as follows. A score of C or higher was considered acceptable for practical use.

[0199] A: The average number of pinholes is 2 (per meter). 2 ) is less than. B: The average number of pinholes is 2 (per meter). 2 ) or more than 5 pieces (pieces / m 2 ) is less than. C: The average number of pinholes is 5 (per meter). 2 ) or more than 10 (pieces / m 2 ) is less than. D: The average number of pinholes is 10 (per meter). 2 ) or more than 20 (pieces / m 2 ) is less than. E: The number of pinholes is 20 on average (per meter). 2 That's all.

[0200] [Table 4]

Claims

1. At a minimum, support (a) and A photosensitive resin composition layer (b) laminated on the support (a), An infrared ablation layer (c) laminated on the photosensitive resin composition layer (b), A peel force adjusting layer (d) is laminated on the infrared ablation layer (c), A cover film (f) is laminated on the peel force adjusting layer (d), Equipped with, The infrared ablation layer (c) contains a resin having a constituent unit c1 represented by the following general formula (1), In analysis of the peeling force adjustment layer (d) by time-of-flight secondary ion mass spectrometry (TOF-SIMS), When the intensity of the negative ion C2H (m / z = 25) is set to 1, and the intensity of the positive ion C2H3 (m / z = 27) is set to 1, The intensity of C2N3 (m / z = 66) is between 0.30 and 7.

00. The intensity of C6H5 (m / z = 77) is between 0.05 and 0.

40. Photosensitive resin composition for flexo printing plates. 【Chemistry 1】 (Here, in equation (1), R 1 and R 2 Each of these independently represents a nonpolar group, R 3 and R 4 Each of these independently represents either a hydrogen atom or a nonpolar group.

2. The photosensitive resin structure for flexographic printing plates according to claim 1, wherein the peeling force adjusting layer (d) has a C3H5 (m / z = 41) intensity of 3.00 or more and 16.00 or less as determined by time-of-flight secondary ion mass spectrometry (TOF-SIMS).

3. The photosensitive resin structure for a flexographic printing plate according to claim 1 or 2, wherein the cover film (f) contains polyethylene terephthalate.

4. R in the general formula (1) 1 and R 2 The photosensitive resin structure for flexographic printing plates according to any one of claims 1 to 3, wherein the alkyl group is an alkyl group.

5. The photosensitive resin structure for flexographic printing plates according to any one of claims 1 to 4, wherein the resin comprises, in addition to the constituent unit (c1), a constituent unit (c2) derived from a monovinyl-substituted aromatic hydrocarbon.

6. The photosensitive resin structure for flexographic printing plates according to any one of claims 1 to 5, wherein the nonpolar group is a group composed of a carbon atom and / or a silicon atom and a hydrogen atom.

7. Using the photosensitive resin structure for flexographic printing plates described in any one of claims 1 to 6, A first step involves irradiating ultraviolet light from the support (a) side, A second step involves irradiating the infrared ablation layer (c) with infrared light to draw a pattern, A third step involves using the infrared ablation layer (c) on which the pattern has been drawn as a mask to irradiate the photosensitive resin composition layer (b) with ultraviolet light to expose the pattern, The method comprises a fourth step of removing the unexposed portions of the infrared ablation layer (c) and the photosensitive resin composition layer (b), A method for manufacturing flexographic printing plates.

8. A fifth step is to print using a flexographic printing plate manufactured by the manufacturing method described in claim 7, Flexographic printing method.

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