Method for producing a photosensitive printing original plate and a relief printing plate

Abstract

Provided is a photosensitive printing original plate having few mask defects (defects) and capable of preventing substance transfer from the heat-sensitive mask layer (excellent in stability over time). The photosensitive printing original plate is formed by laminating at least (A) a support, (B) a photosensitive resin layer, and (C) a heat-sensitive mask layer in this order, wherein the (C) heat-sensitive mask layer contains (a) a partially saponified polyvinyl alcohol, (b) an ultraviolet absorber, and (c) carbon black, and the (b) ultraviolet absorber contains (b-1) an acrylic resin. Also provided is a method for producing a photosensitive relief printing plate using this photosensitive printing original plate.

Description

Technical Field

[0001] The present invention relates to a photosensitive printing original plate and a method for manufacturing a photosensitive relief printing plate.

Background Art

[0002] In the field of flexographic printing, computer-to-plate technology (CTP technology), known as digital imaging technology, has become extremely common. The CTP technology is a method of directly outputting information processed on a computer onto a thermosensitive mask layer to obtain a relief uneven pattern. This technology eliminates the need for the manufacturing process of negative films, and thus can reduce costs and the time required for negative production.

[0003] In CTP technology, the conventionally used negative film is replaced by an integrated mask formed in a printing plate in order to cover areas that should not be photopolymerized. As a method for obtaining this integrated mask, a method of providing a thermosensitive mask layer having light-shielding properties against chemical radiation on a photosensitive resin layer is known, and a method of forming an image-like mask by dispersing and evaporating (ablating) this thermosensitive mask layer with an infrared laser is widely used (see Patent Document 1).

[0004] The thermosensitive mask layer needs to have light-shielding properties in order to prevent the transmission of chemical radiation through the photosensitive resin layer. As a material having light-shielding properties against chemical radiation, carbon black having infrared absorption ability is generally used and is dispersed in a film-forming binder. As a film-forming binder, since it has excellent water solubility, for example, it is known to blend polyvinyl alcohol (see Patent Document 2).

[0005] In recent years, there has been a demand for higher-definition printed images, and it has been required to form printed images composed of aggregates of fine lines and dots. For this purpose, it is important that the thermal mask layer has no defects. The integrated mask is manufactured, for example, by applying a thermal mask layer on a film such as a polyester film. When applying the thermal mask layer on the film, there is a problem that mask defects (pinholes) occur due to coating unevenness, peeling, etc. In response to this problem, for example, Patent Document 3 proposes a flexographic printing original plate containing carbon black as an infrared absorber, a binder polymer, and a dispersant having a base value of 5 to 100 mg / KOHmg in the thermal mask layer.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] In Patent Document 3, by dispersing carbon black with a dispersant, the frequency of occurrence of mask defects (pinholes) decreases. However, since the dispersion of carbon black is insufficient, mask defects (pinholes) where the pigment partially escapes do not disappear. Therefore, further improvement is desired to eliminate the defects of the photosensitive relief printing plate due to mask defects (pinholes) and form a higher-definition printed image.

[0008] In order to solve the problems of the related art, the present inventor has repeatedly developed a heat-sensitive mask layer in which an ultraviolet absorber is blended with carbon black. According to the findings independently obtained by the present inventors through research and development, a new problem has emerged in that during storage or the like, the ultraviolet absorber migrates from the heat-sensitive mask layer into the photosensitive resin layer, inhibiting photocuring and reducing the reproducibility of high-definition printed images of the photosensitive relief printing plate.

[0009] The present invention has been devised in view of the above circumstances, and an object thereof is to provide a photosensitive printing original plate and a method for manufacturing a photosensitive relief printing plate that have few drawbacks of the photosensitive relief printing plate and can prevent the migration of substances from the heat-sensitive mask layer to the photosensitive resin layer (as a result, having excellent stability over time).

Means for Solving the Problems

[0010] As a result of intensive studies to achieve the above object, the present inventor has found that by the (C) heat-sensitive mask layer in the photosensitive printing original plate containing (a) partially saponified polyvinyl alcohol, (b) an ultraviolet absorbing substance, and (c) carbon black, and the (b) ultraviolet absorbing substance containing a specific ultraviolet absorbing substance, the above problems can be solved, and the present invention has been completed.

[0011] That is, the present invention is composed of the following configurations (1) to (8). (1) A photosensitive printing original plate in which at least (A) a support, (B) a photosensitive resin layer, and (C) a heat-sensitive mask layer are laminated in this order, the (C) heat-sensitive mask layer containing (a) partially saponified polyvinyl alcohol, (b) an ultraviolet absorbing substance, and (c) carbon black, and the (b) ultraviolet absorbing substance containing (b-1) an acrylic resin. (2) The photosensitive printing original plate according to (1), wherein the saponification degree of the (a) partially saponified polyvinyl alcohol is 60 to 90 mol%. (3) The photosensitive printing original plate according to (1), wherein the (b-1) acrylic resin is an aqueous resin. (4) The photosensitive printing original plate according to (1), wherein the (b-1) acrylic resin has a benzotriazole skeleton. (5) The photosensitive printing original plate according to (1), wherein the glass transition temperature (Tg) of the (b-1) acrylic resin is -50°C or higher and 100°C or lower. (6) The photosensitive printing original plate according to (1), wherein the (c) carbon black contains 60 parts by mass or more with respect to 100 parts by mass of the (a) partially saponified polyvinyl alcohol. (7) The photosensitive printing original plate according to (1), wherein the mass ratio of the (c) carbon black to the (b-1) acrylic resin in the (C) heat-sensitive mask layer is 60:40 to 99:1. (8) A method for manufacturing a photosensitive relief printing plate having a non-image portion and an image portion, the method including: a mask forming step of forming an image on the (C) heat-sensitive mask layer of the photosensitive printing original plate according to any one of (1) to (7) to form a mask; an exposure step of exposing the (B) photosensitive resin layer imagewise through the mask after the mask forming step; and a developing step of developing using an aqueous developer after the exposure step to form a non-image portion and an image portion.

Advantages of the Invention

[0012] According to the present invention, since the photosensitive relief printing plate has few drawbacks and the photosensitive printing original plate has excellent stability over time, it is possible to provide a photosensitive printing original plate and a photosensitive relief printing plate capable of producing a high-definition printed image.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail. It should be noted that the following embodiments are examples for explaining the present invention and are not intended to limit the present invention to the following contents. The present invention can be variously modified and implemented within the scope of its gist.

[0014] In this specification, expressions such as "containing" and "including" include concepts such as "containing", "including", "consisting essentially of", and "consisting only of".

[0015] In the numerical ranges described step by step in this specification, the upper limit value or the lower limit value of a numerical range at a certain step can be arbitrarily combined with the upper limit value or the lower limit value of a numerical range at another step. Also, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples or a value uniquely derivable from the examples. Further, in this specification, numerical values connected by "~" mean a numerical range including the numerical values before and after "~" as the lower limit value and the upper limit value.

[0016] <Photosensitive printing original plate> The photosensitive printing original plate of the present invention is formed by laminating at least (A) a support, (B) a photosensitive resin layer, and (C) a thermal mask layer in this order. The (B) photosensitive resin layer is composed of a photosensitive resin composition, and an adhesive layer may be provided between the (A) support and the (B) photosensitive resin layer.

[0017] The adhesive layer is provided to bond the (A) support and the (B) photosensitive resin layer. The adhesive layer may be formed from one layer or a plurality of layers. Also, the adhesive layer preferably contains a binder component and a pigment, and further preferably contains a leveling agent and a curing agent.

[0018] Examples of the binder component used for the adhesive layer include polyester resin, epoxy resin, polyamide resin, polyimide resin, phenol resin, butadiene resin, polyurethane resin, polystyrene-polyisoprene copolymer resin, etc., and these can be used alone or in combination. Among these, particularly preferred binder components are polyester resin and polyurethane resin in terms of solvent resistance.

[0019] <(A) Support> (A) The support is not particularly limited, but a flexible material with excellent dimensional stability is preferred. For example, metal supports such as steel, aluminum, copper, nickel, etc., and thermoplastic resin supports such as polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, or polycarbonate film can be mentioned. Among these, a polyethylene terephthalate film with excellent dimensional stability and sufficiently high viscoelasticity is particularly preferred. The thickness of the support is desirably 50 - 350 μm, preferably 100 - 250 μm, considering mechanical properties, shape stabilization, or handleability during printing plate making.

[0020] <(B) Photosensitive resin layer> The photosensitive printing original plate of the present invention has a (B) photosensitive resin layer on the (A) support. The (B) photosensitive resin layer is composed of a known photosensitive resin composition and is not particularly limited. The composition of the photosensitive resin composition includes, for example, (i) a synthetic polymer compound, (ii) a compound having an ethylenic double bond, and (iii) a photoinitiator. The photosensitive resin composition may further contain other additives such as a thermal polymerization inhibitor, a plasticizer, a dye, a pigment, a fragrance, or an antioxidant in addition to the above components (i) - (iii). Hereinafter, the constituent components (i) - (iii) of the photosensitive resin composition will be described in detail.

[0021] <(i) Synthetic polymer compound> (i) The synthetic polymer compound is not particularly limited, and conventionally known soluble synthetic polymer compounds can be used. For example, polyether amide (e.g., JP-A-55-79437), polyether ester amide (e.g., JP-A-58-113537), tertiary nitrogen-containing polyamide (e.g., JP-A-50-76055), ammonium salt type tertiary nitrogen atom-containing polyamide (e.g., JP-A-53-36555), addition polymer of an amide compound having one or more amide bonds and an organic diisocyanate compound (e.g., JP-A-58-140737), addition polymer of a diamine having no amide bond and an organic diisocyanate compound (e.g., JP-A-4-97154), modified polyvinyl alcohol (WO2014 / 021322), etc. From the viewpoint of forming a high-definition printed image, it is preferable that the synthetic polymer compound includes a tertiary nitrogen atom-containing polyamide and an ammonium salt type tertiary nitrogen atom-containing polyamide.

[0022] (B) The content of the synthetic polymer compound in the photosensitive resin layer is preferably 30 to 70% by mass.

[0023] <(ii) Compound having an ethylenic double bond> (ii) A compound having an ethylenic double bond refers to a compound having an ethylenic double bond and a molecular weight of less than 10,000. The molecular weight of the compound having an ethylenic double bond is preferably 2,000 or less. Examples of the compound having an ethylenic double bond include (meth)acrylates which are esterification products of (meth)acrylic acid and alcohol compounds or addition reaction products of (meth)acrylic acid and glycidyl compounds, (meth)acrylamides which are amidation products of (meth)acrylic acid and amine group-containing compounds, and the like. These may be used alone or in combination of two or more. Here, (meth)acrylate is a general term for acrylate and methacrylate, and (meth)acrylic acid is a general term for acrylic acid and methacrylic acid. From the viewpoint of forming a high-definition printed image, it is preferable that the compound having an ethylenic double bond contains (meth)acrylates which are esterification products of (meth)acrylic acid and alcohol compounds or addition reaction products of (meth)acrylic acid and glycidyl compounds.

[0024] (B) The content of the compound having an ethylenic double bond in the photosensitive resin layer is preferably 10 to 60% by mass.

[0025] <(iii) Photoinitiator> (iii) Examples of the photoinitiator include benzophenones, benzoins, acetophenones, benzyls, benzoin alkyl ethers, benzyl alkyl ketals, anthraquinones, thioxanthones, etc. Specifically, benzophenone, phenyl ketones, chlorobenzophenone, benzoin, acetophenone, benzyl, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyldimethyl ketal, benzyldiethyl ketal, benzyldiisopropyl ketal, anthraquinone, 1-hydroxycyclohexan-1-yl phenyl ketone, 2-ethylanthraquinone, 2-methylanthraquinone, 2-allyl anthraquinone, 2-chloroanthraquinone, thioxanthone, 2-chlorothioxanthone, etc. are included. These may be used alone or in combination of two or more. From the viewpoint of forming a high-definition printed image, it is preferable to contain benzyldimethyl ketal, benzyldiethyl ketal, or benzyldiisopropyl ketal as the photoinitiator.

[0026] (B) The content of the photoinitiator in the photosensitive resin layer is preferably 0.1 to 10% by mass.

[0027] <(C) Thermal mask layer> The photosensitive printing original plate of the present invention has a (C) thermal mask layer on the (B) photosensitive resin layer. The (C) thermal mask layer has a function of absorbing an infrared laser and converting it into heat, and a function of blocking ultraviolet light.

[0028] (C) The thermal mask layer contains (a) partially saponified polyvinyl alcohol, (b) an ultraviolet absorber, and (c) carbon black, and is characterized in that the (b) ultraviolet absorber contains (b-1) an acrylic resin. The (C) thermal mask layer may further contain other additives such as a polymerization inhibitor, a surfactant, an antifoaming agent, a fragrance, etc. in addition to the components (a) to (c) above. Hereinafter, the constituent components (a) to (c) of the (C) thermal mask layer will be described in detail.

[0029] (a) Partially Saponified Polyvinyl Alcohol (a) The saponification degree of the partially saponified polyvinyl alcohol is preferably 60 mol% or more and 90 mol% or less. If it is within this range, the (C) thermosensitive mask layer can further improve its solubility in a developer mainly composed of water, and good developability and dispersibility of carbon black can be obtained.

[0030] (a) The average degree of polymerization of the partially saponified polyvinyl alcohol is preferably in the range of 300 or more and 3000 or less, and more preferably 800 or more and 2500 or less. Here, the average degree of polymerization of the (a) partially saponified polyvinyl alcohol refers to the average degree of polymerization of the entire (a) partially saponified polyvinyl alcohol contained in the (C) thermosensitive mask layer. When two or more types are included, it refers to the average degree of polymerization of the entire two or more types of (a) partially saponified polyvinyl alcohol. When the average degree of polymerization of the (a) partially saponified polyvinyl alcohol is in the range of 300 or more and 3000 or less, it is preferable in terms of obtaining better film strength and film-forming properties. The average degree of polymerization can be obtained by dividing the number average molecular weight of the polyvinyl alcohol before saponification by the molecular weight of the polyvinyl alcohol.

[0031] (a) The partially saponified polyvinyl alcohol is preferably contained in an amount of 10 to 80 parts by mass, more preferably 20 to 70 parts by mass, and still more preferably 30 to 60 parts by mass, based on 100 parts by mass of the solid content in the (C) thermosensitive mask layer. When the (a) partially saponified polyvinyl alcohol is contained in an amount of 10 to 80 parts by mass based on 100 parts by mass of the solid content in the (C) thermosensitive mask layer, ablation is easy, and good water developability and good film-forming properties are easily obtained.

[0032] (C) As a method for making the saponification degree of the (a) partially saponified polyvinyl alcohol in the thermosensitive mask layer 60 mol% or more and 90 mol% or less, there are a method of using a partially saponified polyvinyl alcohol with a saponification degree of 60 to 90 mol%, a method of using two or more types of partially saponified polyvinyl alcohol, and making the average saponification degree of the entire (a) partially saponified polyvinyl alcohol 60 mol% or more and 90 mol% or less.

[0033] <(b) UV absorber> (b) The UV absorber is characterized by containing (b-1) an acrylic resin. Thereby, since the UV transmittance of the mask defect (pinhole) portion in the photosensitive printing original plate can be suppressed, the defects of the photosensitive relief printing plate can be suppressed. Further, since the migration of the (b) UV absorber from the (C) heat-sensitive mask layer into the (B) photosensitive resin layer can be suppressed, the photosensitive printing original plate has good stability over time, and the reproducibility of a high-definition printed image can be achieved. As a result, it becomes possible to form a printed image of fine lines or an aggregate of dots of 10 to 20 μm.

[0034] (b) The UV absorber is preferably a substance that absorbs UV rays in a wide wavelength range. For example, benzotriazole-based UV absorbers, benzophenone-based UV absorbers, conjugated diene-based UV absorbers, avobenzone-based UV absorbers, azoresorcinol-based UV absorbers, triazine-based UV absorbers, etc. can be mentioned. From the viewpoint of excellent light absorption ability for UVB (280 to 320 nm) and UVA (320 to 400 nm), it is preferable to use a benzotriazole-based UV absorber.

[0035] In this specification, "(b-1) acrylic resin" refers to a resin containing at least one structural unit selected from the group consisting of a structural unit derived from acrylic acid, a structural unit derived from methacrylic acid, a structural unit derived from an acrylic acid ester, and a structural unit derived from a methacrylic acid ester.

[0036] The concept of (b-1) acrylic resin includes, for example, a homopolymer of acrylic acid, a homopolymer of methacrylic acid, a homopolymer of an acrylic acid ester, a homopolymer of a methacrylic acid ester, a copolymer of acrylic acid and another monomer, a copolymer of methacrylic acid and another monomer, a copolymer of an acrylic acid ester and another monomer, a copolymer of a methacrylic acid ester and another monomer, etc.

[0037] (b-1) The acrylic resin has an ultraviolet-absorbing skeleton. Examples of the ultraviolet-absorbing skeleton include a benzotriazole skeleton, a benzophenone skeleton, an avobenzone skeleton, an azoresorcinol skeleton, and a triazine skeleton. From the viewpoint of excellent light absorption ability and suppressing the ultraviolet transmittance of the mask defect (pinhole) portion, it is preferable that the (b-1) acrylic resin has a benzotriazole skeleton.

[0038] (b-1) The acrylic resin is preferably a copolymer of a monomer having an ultraviolet-absorbing skeleton and a monomer for forming the acrylic resin.

[0039] The monomer having an ultraviolet-absorbing skeleton in the (b-1) acrylic resin is preferably contained in the (b-1) acrylic resin in an amount of 20% by mass or more and 90% by mass or less, more preferably in an amount of 30% by mass or more and 80% by mass or less, and even more preferably in an amount of 40% by mass or more and 70% by mass or less.

[0040] Examples of the monomer having a benzotriazole skeleton include a monomer having a resorcinol type benzotriazole skeleton and a monomer having an alkanol phenol type benzotriazole skeleton. Examples of the monomer having a resorcinol type benzotriazole skeleton include 2-acryloyloxyethyl-2-(2-hydroxy-4-methoxyphenyl)-2H-benzotriazole-5-carboxylate, 2-methacryloyloxyethyl-2-(2-hydroxy-4-methoxyphenyl)-2H-benzotriazole-5-carboxylate, 2-methacryloyloxyethyl-2-(4-benzoyloxy-2-hydroxyphenyl)-2H-benzotriazole-5-carboxylate, 2-methacryloyloxyethyl-2-(2-hydroxy-4-methacryloyloxyphenyl)-2H-benzotriazole-5-carboxylate, 2-methacryloyloxyethyl-2-(2-hydroxy-4-octyloxyphenyl)-2H-benzotriazole-5-carboxylate, and the like, but are not limited thereto. These can be used alone or in combination of two or more kinds.

[0041] Examples of monomers having an alkanol phenol type benzotriazole skeleton include 2-[2-hydroxy-5-(methacryloyloxymethyl)phenyl]-2H-benzotriazole, 2-[2-hydroxy-5-(acryloyloxymethyl)phenyl]-2H-benzotriazole, 2-[2-hydroxy-5-(methacryloyloxyethyl)phenyl]-2H-benzotriazole, 2-[2-hydroxy-5-(acryloyloxyethyl)phenyl]-2H-benzotriazole, 2-[2-hydroxy-5-(methacryloyloxypropyl)phenyl]-2H-benzotriazole, 2-[2-hydroxy-5-(acryloyloxypropyl)phenyl]-2H-benzotriazole, 2-[2-hydroxy-5-(methacryloyloxybutyl)phenyl]-2H-benzotriazole, 2-[2-hydroxy-5-(acryloyloxybutyl)phenyl]-2H-benzotriazole, 2-[2-hydroxy-5-(methacryloyloxyhexyl)phenyl]-2H-benzotriazole, 2-[2-hydroxy-5-(acryloyloxyhexyl)phenyl]-2H-benzotriazole, 2-[2-hydroxy-3-t-butyl-5-(methacryloyloxyethyl)phenyl]-2H-benzotriazole, 2-[2-hydroxy-3-t-butyl-5-(acryloyloxyethyl)phenyl]-2H-benzotriazole, 2-[2-hydroxy-5-(methacryloyloxyethyl)phenyl]-5-chloro-2H-benzotriazole, 2-[2-hydroxy-5-(acryloyloxyethyl)phenyl]-5-chloro-2H-benzotriazole, 2-[2-hydroxy-5-(methacryloyloxyethyl)phenyl]-5-methoxy-2H-benzotriazole, 2-[2-hydroxy-5-(acryloyloxyethyl)phenyl]-5-methoxy-2H-benzotriazole, 2-[2-hydroxy-5-(methacryloyloxyethyl)phenyl]-5-cyano-2H-benzotriazole, 2-[2-hydroxy-5-(acryloyloxyethyl)phenyl]-5-cyano-2H-benzotriazole, 2-[2-hydroxy-5-(methacryloyloxyethyl)phenyl]-5-t-butyl-2H-benzotriazole,Examples include, but are not limited to, 2-[2-hydroxy-5-(acryloyloxyethyl)phenyl]-5-t-butyl-2H-benzotriazole, 2-[2-hydroxy-5-(methacryloyloxyethyl)phenyl]-5-nitro-2H-benzotriazole, 2-[2-hydroxy-5-(acryloyloxyethyl)phenyl]-5-nitro-2H-benzotriazole, etc. These can be used alone or in combination of two or more. Furthermore, a monomer having a resorcinol-type benzotriazole skeleton and a monomer having an alkanolphenol-type benzotriazole skeleton can be used in combination.

[0042] Specific examples of the monomers for forming the acrylic resin include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, acetoxyethyl (meth)acrylate, phenyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(2-methoxyethoxy)ethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, diethylene glycol monophenyl ether (meth)acrylate, triethylene glycol monomethyl ether (meth)acrylate, triethylene glycol monoethyl ether (meth)acrylate, dipropylene glycol monomethyl ether (meth)acrylate, polyethylene glycol monomethyl ether (meth)acrylate, polypropylene glycol monomethyl ether (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polybutylene glycol mono(meth)acrylate, polyethylene glycol-polypropylene glycol mono(meth)acrylate, hydroxyphenyl (meth)acrylate, hydroxybenzyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, and the like. These can be used alone or in combination of two or more kinds.

[0043] When copolymerizing a monomer having a benzotriazole skeleton with a monomer for forming an acrylic resin, known polymerization methods such as solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, etc. can be employed. Also, known methods can be used for the preparation method such as the method of mixing raw materials containing a monomer having a benzotriazole skeleton, and it is not particularly limited.

[0044] Specific examples of commercially available acrylic resins having a benzotriazole skeleton include the aqueous Newcoat UVA series (e.g., Newcoat UVA-101, Newcoat UVA-102, Newcoat UVA-103, Newcoat UVA-104, Newcoat UVA-204W) manufactured by Shin-Nakamura Chemical Co., Ltd., the solvent-based Vanarezine UVA series (e.g., Vanarezine UVA-5080, hydroxyl group-introduced type Vanarezine UVA-5080(OHV20), Vanarezine UVA-55T, high hydroxyl value type Vanarezine UVA-55MHB, Vanarezine UVA-7075, hydroxyl group-introduced type Vanarezine UVA-7075(OHV20), and Vanarezine UVA-73T), the ultraviolet absorber for aqueous coating (e.g., ULS-1700) manufactured by Lion Specialty Chemicals Co., Ltd., the ultraviolet absorber for solvent-based coating (ULS-935LH, ULS-1935LH, ULS-1933D), the aqueous acrylic urethane resin (e.g., Sunnaron MW-022) manufactured by Yamana Synthetic Chemical Co., etc. These can be used alone or in combination of two or more.

[0045] (b) From the viewpoint of suppressing the migration of the ultraviolet absorber from the (C) heat-sensitive mask layer into the (B) photosensitive resin layer (excellent stability over time), it is preferable that the weight-average molecular weight of the acrylic resin is 1,000 to 200,000. More preferably, the polymerization average molecular weight is 2,000 to 100,000. The weight-average molecular weight of the (b) ultraviolet absorbing substance containing the acrylic resin can be determined in terms of polystyrene conversion using gel permeation chromatography (GPC).

[0046] (C) The content of the (b-1) acrylic resin in the heat-sensitive mask layer is preferably 1.0% by mass or more and 40% by mass or less, more preferably 1.5% by mass or more and 30% by mass or less, based on the total solid content of the (C) heat-sensitive mask layer, from the viewpoint of suppressing the ultraviolet transmittance of the mask defect (pinhole) portion.

[0047] The (b-1) acrylic resin is preferably an aqueous acrylic resin. Thereby, high developability in an aqueous developer can be imparted to the (C) heat-sensitive mask layer. The aqueous acrylic resin is a resin having water solubility or water dispersibility, and means a resin that can be dissolved or dispersed at least 1 g per 100 ml of water at 50°C, preferably at least 5 g per 100 ml of water at 50°C.

[0048] The aqueous acrylic resin can be obtained, for example, by copolymerizing a known hydrophilic monomer component as a monomer for forming the acrylic resin, or by introducing a hydroxyl group, a carboxy group, or a sulfonium group into the side chain and / or the terminal of the acrylic resin. To improve the water dispersibility, a known surfactant may be further used.

[0049] As the hydrophilic monomer component, a hydroxyl group-containing monomer is preferable. Examples of the hydroxyl group-containing monomer include those in which a hydroxyl group is bonded to an alkyl group or an aromatic ring of the above acrylic acid esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, hydroxyphenyl (meth)acrylate, and hydroxybenzyl (meth)acrylate.

[0050] Specific examples of the aqueous acrylic resin include the aqueous Newcoat UVA series manufactured by Shin-Nakamura Chemical Co., Ltd., ULS-1700, an ultraviolet absorber for aqueous coating manufactured by Lion Specialty Chemicals Co., Ltd., and Sannaron MW-022, an aqueous acrylic urethane resin manufactured by Yamami Synthetic Chemical Co., Ltd.

[0051] (b-1) The glass transition temperature (Tg) of the acrylic resin is preferably -50°C or higher and 100°C or lower, more preferably -40°C or higher and 80°C or lower, and even more preferably -30°C or higher and 50°C or lower, from the viewpoints of improving the flexibility of the thermal mask layer, improving the compatibility with the partially saponified polyvinyl alcohol, and further suppressing the defects of the photosensitive relief printing plate.

[0052] <(c) Carbon black> (c) Carbon black acts as an infrared absorber, which is a substance that absorbs infrared rays and converts them into heat, and also has a function of blocking ultraviolet light. As the infrared absorbing substance, in addition to (c) carbon black, substances having absorption characteristics in the wavelength range of 750 nm to 20,000 nm may be included. Examples of the infrared absorbing substance include, in addition to carbon black, black pigments such as carbon graphite and cyanine black, inorganic pigments such as manganese oxide, iron oxide, chromium oxide, and copper chromite, and dyes such as phthalocyanine, substituted phthalocyanine derivatives, cyanine dyes, merocyanine dyes, polymethine dyes, and metal thiolate dyes. The infrared absorbing substance may contain two or more kinds in addition to carbon black.

[0053] (C) The content of (c) carbon black in the thermal mask layer is preferably 30 parts by mass or more and more preferably 70 parts by mass or more with respect to 100 parts by mass of the partially saponified polyvinyl alcohol (a) from the viewpoint of improving the ablation efficiency. In this case, the shielding property of chemical radiation is further excellent and the ablation efficiency is good.

[0054] (C) The content of (c) carbon black in the heat-sensitive mask layer is preferably 20% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 55% by mass or less, even more preferably 30% by mass or more and 50% by mass or less, and still more preferably 35% by mass or more and 45% by mass or less with respect to the total solid content of the (C) heat-sensitive mask layer, because it can suppress mask defects (pinholes), has better shielding properties against chemical radiation, and has good ablation efficiency.

[0055] (C) The optical density of the heat-sensitive mask layer is preferably 2.0 or more because it has better shielding properties against chemical radiation and good ablation efficiency. The upper limit is not particularly limited, but from the perspective of operability, for example, it is 5.0 or less. The optical density can be measured, for example, using a black-and-white transmission densitometer DM-520 (manufactured by Dainippon Screen Mfg. Co., Ltd.).

[0056] (C) The layer thickness of the heat-sensitive mask layer is preferably 0.5 to 3.5 μm, more preferably 1.0 to 3.0 μm. If it is above the above lower limit, high coating technology is not required and a certain optical density can be obtained. Also, if it is below the above upper limit, high energy is not required for the evaporation of the (C) heat-sensitive mask layer, which is cost-effective.

[0057] (C) The mass ratio of (c) carbon black to (b-1) acrylic resin in the heat-sensitive mask layer is preferably 60:40 to 99:1. More preferably, it is 65:35 to 98:2. Even more preferably, it is 70:30 to 90:10. By containing the (b-1) acrylic resin in the above mass ratio with respect to (c) carbon black, mask defects (pinholes) can be further suppressed, and the ultraviolet light transmittance at the mask defect (pinhole) part can be further suppressed. As a result, the defects of the photosensitive relief printing plate can be more suppressed, and the reproducibility of a high-definition printed image is easily achieved.

[0058] <Cover Film> The photosensitive printing original plate of the present invention may have a cover film on the (C) heat-sensitive mask layer. The cover film is a layer for protecting the photosensitive printing original plate, and a flexible cover film is preferred. As the cover film, a peelable one is preferred, and examples thereof include a polyethylene terephthalate film, a polyethylene naphthalate film, and a polybutylene terephthalate film.

[0059] The surface of the cover film (the surface on which the (C) heat-sensitive mask layer is formed) may be subjected to a release treatment for suppressing the adhesion of the (C) heat-sensitive mask layer and enhancing the peelability of the cover film. Examples of such a release treatment include a method of forming a release layer by applying a release agent to the surface of the cover film. Examples of the release agent include a silicone-based release agent and an alkyl-based release agent. Further, the thickness of the cover film is preferably 25 to 250 μm.

[0060] <Functional layer> The photosensitive printing original plate of the present embodiment may include an optional functional layer between the above-described (B) photosensitive resin layer and (C) heat-sensitive mask layer. The functional layer is not particularly limited, but for example, an oxygen barrier layer and / or an adhesive layer can also be provided.

[0061] The oxygen barrier layer can be provided to obtain a photosensitive relief printing plate with even better reproducibility of high-definition printed images. By having the oxygen barrier layer, it is possible to prevent the radical generation compound and oxygen from reacting during the radical polymerization reaction by exposure and suppressing the polymerization reaction.

[0062] When providing an oxygen barrier layer, examples of the binder polymer in the oxygen barrier layer include polyvinyl alcohol, partially saponified polyvinyl acetate, alkyl cellulose, cellulose-based polymers, and polyamides. These polymers may be used alone or in combination of two or more types. Preferred binder polymers in terms of oxygen barrier properties include, for example, polyvinyl alcohol, partially saponified polyvinyl acetate, polyamides, etc. Examples of the partially saponified polyvinyl acetate include partially saponified polyvinyl acetate with a saponification degree of 60 to 98 mol%. Examples of the polyamide include polyamide resins containing a basic nitrogen atom in the molecule and polyamide resins containing an alkylene glycol structural unit in the molecule. However, an oxygen barrier layer (Patent No. 7243076) containing a polyamide resin containing a basic nitrogen atom in the molecule and a polyamide resin containing an alkylene glycol structural unit in the molecule is preferred.

[0063] Further, the adhesive layer can be provided to improve the adhesiveness between the (B) photosensitive resin layer and the (C) heat-sensitive mask layer. Thereby, the handleability tends to be further improved.

[0064] <Method for producing a photosensitive printing original plate> The method for producing the photosensitive printing original plate of the present invention is not particularly limited. For example, a composition for a heat-sensitive mask layer is applied to a cover film and dried to obtain a laminate I composed of (C) heat-sensitive mask layer / cover film. Next, a laminate II is obtained by applying a composition for a photosensitive resin layer on the surface of an (A) support coated with an adhesive on the surface where the adhesive is applied. Then, the (C) heat-sensitive mask layer side of the laminate I and the (B) photosensitive resin layer side of the laminate II are laminated together with a laminator to produce a photosensitive printing original plate in which the (A) support, (B) photosensitive resin layer, and (C) heat-sensitive mask layer are laminated in this order. Examples of such methods include this.

[0065] <Method for producing a photosensitive relief printing plate> The manufacturing method of a photosensitive relief printing plate having a non-image part and an image part of the present invention includes a mask forming step of forming an image on the (C) heat-sensitive mask layer of the photosensitive printing original plate of the present invention described above to form a mask, and an exposure step of exposing the (B) photosensitive resin layer imagewise through the mask after the mask forming step, and a developing step of developing using an aqueous developer after the exposure step to form a non-image part and an image part.

[0066] <Mask forming step> The mask forming step is a step of forming an image on the (C) heat-sensitive mask layer to form a mask used in the exposure step described later. Here, the (C) heat-sensitive mask layer generates heat by the action of an infrared absorber (carbon black) when irradiated imagewise with an IR laser, and a thermally decomposable compound decomposes by the action of the heat, and the heat-sensitive mask layer is selectively removed to form it.

[0067] Examples of suitable IR lasers include an ND / YAG laser (1064 nm) or a diode laser (e.g., 830 nm). Laser systems suitable for computer plate-making technology are commercially available, and for example, CDI (Esco Graphics) can be used. This laser system includes a rotating cylindrical drum for holding the printing original plate, an irradiation device for the IR laser, and a layout computer, and the image information is directly transferred from the layout computer to the laser device.

[0068] <Exposure step> The exposure step is a step of exposing the (B) photosensitive resin layer imagewise through the mask obtained in the mask forming step described above, and the (B) photosensitive resin layer is irradiated with actinic rays over the entire surface through an imagewise mask (main exposure). Thereby, crosslinking and / or polymerization of the irradiated area of the actinic rays can be induced and cured.

[0069] The exposure process can be carried out with the plate attached to the laser cylinder, but it is advantageous and common to remove the plate from the laser device and irradiate it with a conventional flat irradiation unit, as it can accommodate non-standard plate sizes. As the actinic ray, ultraviolet rays having an emission peak at a wavelength of 330 to 380 nm can be used. As the light source, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a zirconium lamp, a carbon arc lamp, a fluorescent lamp for ultraviolet rays, an LED-UV (ultraviolet light source using a light-emitting diode), etc. can be used.

[0070] <Development process> The development process is a process of developing using a developer to form a non-image part and an image part. The developer used in the development process is not particularly limited, and a conventionally known developer can be used. However, from the viewpoint of reducing the environmental load, it is preferable to use an aqueous developer containing 50% by mass or more of water. The water content in the aqueous developer is preferably 80 to 99.9% by mass, more preferably 90 to 99.9% by mass, based on the total mass of the aqueous developer.

[0071] <Rinsing process> The method for manufacturing a photosensitive relief printing plate of the present invention preferably has a rinsing process of rinsing the surfaces of the non-image part and the image part formed in the development process with water after the above-described development process.

[0072] Examples of the rinsing means in the rinsing process include a method of rinsing with tap water, a method of spraying high-pressure water, and a method of mainly brushing the surfaces of the non-image part and the image part with a brush in the presence of water using a conveyor-type brush developing machine as a developing machine for the photosensitive relief printing plate.

[0073] <Back exposure process> The method for manufacturing a photosensitive relief printing plate of the present invention preferably has a back exposure process of irradiating ultraviolet rays from the support side of the photosensitive printing original plate before the above-described mask forming process or the above-described exposure process.

[0074] <Post-exposure process> The method for manufacturing a photosensitive relief printing plate of the present invention preferably has a post-exposure step of irradiating ultraviolet rays from the photosensitive resin layer side of the photosensitive printing original plate after the above-described development step or the above-described rinsing step.

Example

[0075] The effects of using the photosensitive resin composition of the present invention are shown in the following examples, but the present invention is not limited thereto. In the examples, "parts" means parts by mass. Also, the numerical values indicating the composition ratios in the table also mean parts by mass.

[0076] (Example 1) <(Preparation of a support)> To 100 parts of "Vylon 30SS" (a product of Toyobo Co., Ltd., solid content concentration 30%, molecular weight 20,000 to 25,000) as a polyester resin solution, a solution in which 0.5 part of dihydrothio-p-toluidine as an ultraviolet absorber was dissolved in 3.6 parts of dimethylaminoacetamide, and a solution in which 0.2 part of "U-CAT SA102" (a product of San-Apro Ltd., a DBU-octylate composition) as a catalyst was dissolved in 0.7 part of dioxane were prepared. Next, a solution in which 10.2 parts of "Coronate L" (a product of Nippon Polyurethane Industry Co., Ltd.) as a polyfunctional isocyanate was dissolved in 1.4 parts of ethyl acetate was prepared to obtain an adhesive composition solution. This solution was uniformly applied to a 250-μm-thick transparent polyester film support and dried with a hot air dryer at 120°C for 1 minute to obtain a support having a 20-μm-thick transparent adhesive layer.

[0077] <Preparation of a heat-sensitive mask layer coating liquid> Partially saponified polyvinyl alcohol and an ultraviolet absorbing substance were dissolved in water according to the composition (mass ratio) described in the heat-sensitive mask layer coating liquid in Table 1 shown below, and carbon black was dispersed therein to prepare a dispersion liquid, which was used as the heat-sensitive mask layer coating liquid.

[0078] <(C) Preparation of a heat-sensitive mask layer and laminate (I)> As a cover film, a PET film (Toyobo Co., Ltd., E5000, thickness 100 μm) was coated with a thermosensitive mask layer coating solution so that the layer thickness of the thermosensitive mask layer was 1.5 μm, and dried at 120 °C for 5 minutes to laminate the thermosensitive mask layer, thereby producing a cover film and obtaining laminate (I).

[0079] <(B) Preparation of Synthetic Polymer Compound A for Photosensitive Resin Layer> 396 parts of ε-caprolactam, 469 parts of adipic acid, 341 parts of 1,4-bis(3-aminopropyl)piperazine, 199 parts of 1,3-bis(aminomethyl)cyclohexane, 34 parts of isophoronediamine, 5 parts of 50% aqueous hypophosphorous acid solution, and 1000 parts of water were charged into an autoclave. After nitrogen substitution, it was sealed and gradually heated. When the internal pressure reached 0.4 MPa, water was distilled out until the pressure could no longer be maintained, and it was returned to normal pressure in about 2 hours. Then, it was reacted at normal pressure for 1 hour. The maximum polymerization reaction temperature was 255 °C. Thereby, a polyamide containing a tertiary nitrogen atom (polymer compound A) was obtained. The composition of polymer compound A was measured by H-NMR, and it was confirmed that there was no difference between the charged composition and the polymer composition.

[0080] <Preparation of Laminate (II)> 55.0 parts of synthetic polymer compound A was added to a mixture of 62 parts of methanol and 10 parts of water, and it was heated and dissolved at 65 °C. 9.0 parts of diethylene glycol, 5.0 parts of lactic acid as a quaternizing agent, and 0.1 part of hydroquinone monomethyl ether were added and stirred and dissolved for another 30 minutes to quaternize the polyamide to make it water-soluble. Then, 2.5 parts of glycidyl methacrylate (GMA), 1.0 part of benzyl dimethyl ketal as a photoinitiator, 13 parts of glycerin dimethacrylate (Light Ester G101P manufactured by Kyoeisha Chemical Co., Ltd.), and 14.5 parts of propylene glycol diglycidyl ether acrylate adduct (Epoxy Ester 70PA manufactured by Kyoeisha Chemical Co., Ltd.) were added and stirred and dissolved for 30 minutes. Then, the temperature was gradually raised to distill out methanol and water, and it was concentrated until the temperature in the kettle reached 110 °C. At this stage, a fluid and viscous composition for a photosensitive resin layer was obtained. The composition for a photosensitive resin layer was cast on the adhesive composition side of the support prepared above to obtain laminate (II).

[0081] <Production of Photosensitive Printing Master The heat-sensitive mask layer side of the laminate (I) prepared above and the photosensitive resin layer of the laminate (II) were laminated in contact with each other, and a photosensitive printing master of a sheet-like laminate with a total thickness of 1080 μm was formed using a laminator.

[0082] (Examples 2 to 7, Comparative Examples 1 to 2) According to the composition (mass ratio) described in Table 1 below, a heat-sensitive mask layer coating liquid was prepared in the same manner as in Example 1, and a photosensitive printing master of a sheet-like laminate with a total thickness of 1080 μm was formed.

[0083] Details of each material used in the heat-sensitive mask layer coating liquids of Examples 1 to 7 and Comparative Examples 1 to 2 are shown below. (Partially Saponified Polyvinyl Alcohol) · Kuraray Poval 44-88 (Saponification degree: 87 - 89 mol%, average degree of polymerization: about 4400, manufactured by Kuraray Co., Ltd.) · Kuraray Poval 35-80 (Saponification degree: 78.5 - 80.5 mol%, average degree of polymerization: about 3500, manufactured by Kuraray Co., Ltd.) · Kuraray Poval L-10 (Saponification degree: 71.5 - 80.5 mol%, average degree of polymerization: about 1000, manufactured by Kuraray Co., Ltd.) (Ultraviolet Absorbing Substance) · ULS-1700 (Tg: -26°C)… Lion Specialty Chemicals Co., Ltd. · Newcoat UVA-101 (Tg: 7°C)… Shin-Nakamura Chemical Co., Ltd. · Sunalon MW-022 (Tg: 25°C)… Yamami Synthetic Chemical Co., Ltd. · Tinuvin 326 (2-(5-Chloro-2H-benzotriazol-2-yl)-4-methyl-6-tert-butylphenol: non-acrylic resin ultraviolet absorbing substance, Tg: none)… BASF Japan Ltd. (Carbon Black) · NAF5091 Black… Dainichi Seika Kogyo Co., Ltd.

[0084]

Table 1

[0085] The performance of each photosensitive printing original plate thus obtained was evaluated as follows.

[0086] <Optical density> Using a black-and-white transmission densitometer DM-520 (manufactured by Dainippon Screen Mfg. Co., Ltd.), the optical density of the thermosensitive mask layer of the laminate (I) was measured. The optical density is required to be 2.3 or more, preferably 2.5 or more.

[0087] <Number of mask defects in the thermosensitive mask layer of the photosensitive printing original plate> The cover film was peeled off from the photosensitive printing original plates obtained from each of the examples and comparative examples, and in the range of 30 cm × 30 cm, magnified observation was carried out from the side of the thermosensitive mask layer using a loupe, and the number of mask defects (pinholes) of 100 μm or more in the thermosensitive mask layer was counted.

[0088] <Number of defects in the photosensitive relief printing plate> After observation with the above loupe, the photosensitive printing original plate was wound around a CDI4530 manufactured by Esco Graphic Co., Ltd., and the image was imaged at a resolution of 4000 dpi with a grid-like image pattern having a line width of 90 μm and a pitch of 90 μm. Then, ultraviolet rays were irradiated for 5 minutes from a distance of 5 cm from the surface of the photosensitive resin using a chemical lamp adjusted to 3.4 mW / cm 2 Next, development was carried out with tap water at 25 °C using a brush-type washer (120 μmφ nylon brush, JW-A2-PD type manufactured by Nippon Denshikiki Co., Ltd.) to obtain a relief image. After further drying with warm air at 60 °C for 10 minutes, ultraviolet rays were irradiated for 30 seconds with an ultra-high pressure mercury lamp to produce a 30 cm square photosensitive relief printing plate. The obtained photosensitive relief printing plate was magnified and observed using a loupe, and the number of defects (parts where the convex part of the image is missing) of 100 μ or more in the photosensitive relief printing plate was counted. Evaluation was carried out according to the following criteria, and the results are summarized in Table 2. 〇: (Number of defects in the thermosensitive mask layer) ≥ (Number of defects in the photosensitive relief printing plate), and the number of defects in the photosensitive relief printing plate is 0 △: (Number of defects in the heat-sensitive mask layer) > (Number of defects in the photosensitive relief printing plate) ×: (Number of defects in the heat-sensitive mask layer) ≤ (Number of defects in the photosensitive relief printing plate)

[0089]

Table 2

[0090] <Evaluation of the Aging Stability of the Photosensitive Printing Master>[ To evaluate the aging stability of the photosensitive printing master, after preparing the photosensitive printing master, the image reproducibility when making a photosensitive relief printing plate was evaluated for (i) the photosensitive printing master stored for 15 days in an environment of 20°C and (ii) the photosensitive printing master stored for 90 days in an environment of 50°C. The images used for the evaluation were images in which the diameter of independent points (independent dots) was 200, 300, 400, 500, 600 μm and the line width of independent lines (independent lines) was 40, 60, 80, 100, 120, 140 μm. The photosensitive relief printing plate was prepared in the same manner as <Number of defects in the photosensitive relief printing plate>. The evaluation of the aging stability was carried out for the minimum reproduced independent point diameter and the minimum independent line width, and each photosensitive relief printing plate obtained from (i) and (ii) above was evaluated as follows, and the results were summarized in Table 3. 〇: When comparing the photosensitive relief printing plates obtained from (i) and (ii), those in which no change was observed in the reproducibility of the minimum independent points and the reproducibility of the minimum independent lines △: When comparing the photosensitive relief printing plates obtained from (i) and (ii), those in which only one of the reproducibility of the minimum independent points or the reproducibility of the minimum independent lines was worse for the one obtained from (ii) ×: When comparing the photosensitive relief printing plates obtained from (i) and (ii), those in which both the reproducibility of the independent points and the reproducibility of the lines were worse for the one obtained from (ii)

[0091]

Table 3

[0092] As can be seen from Tables 2 to 3, all of Examples 1 to 7 that meet the requirements of the present invention have few drawbacks in the photosensitive relief printing plate, and the reproducibility of independent points and independent lines when producing the photosensitive relief printing plate from the photosensitive printing original stored for 15 days in a 20°C environment and for 90 days in a 50°C environment is all good without change. Therefore, it was found that the photosensitive printing original of the present invention is excellent in stability over time and can reproduce a high-definition printed image. In Comparative Example 1, since no ultraviolet absorber was blended, it was not possible to suppress the ultraviolet transmittance at the mask defect (pinhole) portion. In Comparative Example 2, since it does not contain an acrylic resin as the ultraviolet absorber, it is inferior in stability over time and cannot reproduce a high-definition printed image.

Industrial Applicability

[0093] Since the present invention has few drawbacks in the photosensitive relief printing plate and is excellent in the stability over time of the photosensitive printing original, it is possible to provide a photosensitive printing original and a photosensitive relief printing plate capable of producing a high-definition printed image. Therefore, the present invention is extremely useful in the art.

Claims

1. A photosensitive printing original plate, comprising at least (A) a support, (B) a photosensitive resin layer, and (C) a thermal mask layer laminated in this order, wherein the (C) thermal mask layer contains (a) a partially saponified polyvinyl alcohol, (b) an ultraviolet absorber, and (c) carbon black, and the (b) ultraviolet absorber contains (b-1) an acrylic resin.

2. The photosensitive printing original plate according to claim 1, wherein the degree of saponification of the (a) partially saponified polyvinyl alcohol is 60 to 90 mol%.

3. The photosensitive printing original plate according to claim 1, wherein the (b-1) acrylic resin is an aqueous resin.

4. The photosensitive printing original plate according to claim 1, wherein the (b-1) acrylic resin has a benzotriazole skeleton.

5. The photosensitive printing original plate according to claim 1, wherein the glass transition temperature (Tg) of the (b-1) acrylic resin is -50°C or higher and 100°C or lower.

6. The photosensitive printing original plate according to claim 1, wherein the (c) carbon black contains 60 parts by mass or more with respect to 100 parts by mass of the (a) partially saponified polyvinyl alcohol.

7. The photosensitive printing original plate according to claim 1, wherein the mass ratio of the (c) carbon black to the (b-1) acrylic resin in the (C) thermal mask layer is 60:40 to 99:

1.

8. A method for manufacturing a photosensitive relief printing plate having a non-image portion and an image portion, comprising: a mask forming step of forming an image on the (C) thermal mask layer of the photosensitive printing original plate according to any one of claims 1 to 7 to form a mask; an exposure step of exposing the (B) photosensitive resin layer imagewise through the mask after the mask forming step; and a developing step of developing using an aqueous developer after the exposure step to form a non-image portion and an image portion.

Images