Method for producing image-forming laminate and flexographic printing plate

Abstract

The present invention addresses the problem of providing an image formation laminate that has high sensitivity in a thermosensitive image forming layer and has excellent manufacturing suitability and a method for manufacturing a flexographic printing plate using the same. The image formation laminate of the present invention is an image formation laminate (10) for forming a mask used to manufacture a flexographic printing plate. The image formation laminate (10) has a carrier sheet (6), a barrier layer (3), and a thermosensitive image forming layer (4) in this order. The barrier layer contains a first infrared absorbing dye. The thermosensitive image forming layer contains an ultraviolet absorbing agent and a second infrared absorbing dye. Both the first infrared absorbing dye and the second infrared absorbing dye are compounds that have absorption at a wavelength of 1070 nm and have a mass absorption coefficient of 50 L / (g･cm) or more at a wavelength of 1070 nm. Both the barrier layer and the thermosensitive image forming layer contain a third infrared absorbing dye having absorption at a wavelength of 830 nm.

Description

[Technical field]

[0001] The present invention relates to an image-forming laminate and a method for producing a flexographic printing plate using the same. [Background technology]

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

[0003] In a so-called analog type flexographic printing plate precursor, a negative film (mask) on which a predetermined image has already been formed is placed on top of a photosensitive resin layer, and the predetermined image is exposed onto the surface of the photosensitive resin layer through this negative film. As an example of an image-forming laminate for forming such a negative film (mask), Patent Document 1 describes an image-forming material having, in this order, a carrier sheet, a barrier layer containing a first infrared absorbing compound, and a heat-sensitive image-forming layer containing a second infrared absorbing compound and a second ultraviolet absorbing compound, and using IR absorbing dyes as the first infrared absorbing compound and the second infrared absorbing compound (see, for example, [Claim 1]

[0154] ,

[0167] ,

[0169] , etc.). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2016-524718 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors have studied the image-forming material described in Patent Document 1 and have found that there is room for improvement in the sensitivity of the image formed in the heat-sensitive image-forming layer (infrared ablation layer). Therefore, in order to improve the sensitivity of the heat-sensitive image-forming layer, the present inventors changed the absorption wavelength of the infrared absorbing dye to a longer wavelength side than 830 nm (e.g., 900 to 1200 nm) so that a longer wavelength exposure light source (e.g., a 1070 nm fiber laser) could be used, but it was found that the image-forming material was not suitable for manufacturing.

[0006] Therefore, an object of the present invention is to provide an image-forming laminate having a heat-sensitive image-forming layer with high sensitivity and excellent manufacturability, and a method for producing a flexographic printing plate using the same. [Means for solving the problem]

[0007] As a result of intensive investigations to achieve the above object, the present inventors have found that the infrared absorbing dyes contained in the barrier layer and the heat-sensitive image-forming layer are both compounds that have absorption at a wavelength of 1070 nm and have a mass absorption coefficient at 1070 nm of 50 L / (g cm) or more, and that by the barrier layer and the heat-sensitive image-forming layer further containing an infrared absorbing dye that has absorption at a wavelength of 830 nm, the sensitivity of the heat-sensitive image-forming layer is increased and the manufacturability of the image-forming laminate is also improved, thereby completing the present invention. That is, the present inventors have found that the above object can be achieved by the following configuration.

[0008] [1] An imaging laminate for forming a mask for use in producing flexographic printing plates, comprising: a carrier sheet, a barrier layer, and a heat-sensitive image-forming layer, in that order; the barrier layer contains a first infrared absorbing dye; the heat-sensitive imaging layer contains an ultraviolet absorbing agent and a second infrared absorbing dye; the first infrared absorbing dye and the second infrared absorbing dye are both compounds that have absorption at a wavelength of 1070 nm and have a mass absorption coefficient at a wavelength of 1070 nm of 50 L / (g cm) or more; An imaging laminate, wherein both the barrier layer and the heat-sensitive imaging layer contain a third infrared absorbing dye having absorption at a wavelength of 830 nm. [2] The image-forming laminate according to [1], wherein the content of the compound in the barrier layer that has substantially no absorption in the wavelength region of 900 to 1,200 nm and has absorption in the wavelength region of 300 to 400 nm is 0% by mass or more and less than 0.1% by mass, relative to the mass of the barrier layer. [3] The image-forming laminate according to [1] or [2], wherein the first infrared absorbing dye and the second infrared absorbing dye are both compounds represented by formula (1) described below. [4] A method for producing a flexographic printing plate having non-image areas and image areas, comprising the steps of: a mask forming step of forming an image on the heat-sensitive image forming layer of the image-forming laminate according to any one of [1] to [3] to form a mask; a lamination step of laminating a mask on the photosensitive resin layer of the flexographic printing plate precursor having a support and a photosensitive resin layer after the mask formation step; an exposure step of exposing the photosensitive resin layer to light in an imagewise manner through a mask after the lamination step; a peeling step of peeling the mask from the photosensitive resin layer after the exposure step; A method for producing a flexographic printing plate, comprising a developing step, which is performed after the peeling step, by developing with a developer to form non-image areas and image areas. [5] The photosensitive resin layer contains a monomer, a polymerization initiator, a base polymer, and water-dispersible particles; The water-dispersible particles have a carbon-carbon double bond, The method for producing a flexographic printing plate according to [4], wherein the number of carbon-carbon double bonds on the surface of the water-dispersible particles is 21 or less. [6] The method for producing a flexographic printing plate according to [4] or [5], wherein the developer contains 50% or more by mass of water. [7] The method for producing a flexographic printing plate according to any one of [4] to [6], wherein the developer contains a surfactant represented by formula (2) described below. Effect of the Invention

[0009] According to the present invention, it is possible to provide an image-forming laminate having a high sensitivity of a heat-sensitive image-forming layer and excellent manufacturability, and a method for producing a flexographic printing plate using the same. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing one example of the image-forming laminate of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described in detail below. The following description of the components may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In the present specification, each component may be used alone or in combination of two or more substances corresponding to the component. When two or more substances are used in combination for each component, the content of the component refers to the total content of the substances used in combination, unless otherwise specified.

[0012] [Laminate for image formation] The image-forming laminate of the present invention is an image-forming laminate for forming a mask used in the production of a flexographic printing plate, and is a laminate having a carrier sheet, a barrier layer, and a heat-sensitive image-forming layer in this order. The barrier layer also contains a first infrared absorbing dye. The heat-sensitive imaging layer also contains an ultraviolet absorbing agent and a second infrared absorbing dye. In addition, both the first infrared absorbing dye and the second infrared absorbing dye are compounds that have absorption at a wavelength of 1070 nm and have a mass absorption coefficient at a wavelength of 1070 nm of 50 L / (g·cm) or more. Additionally, both the barrier layer and the heat-sensitive image-forming layer contain a third infrared absorbing dye having absorption at a wavelength of 830 nm.

[0013] FIG. 1 is a schematic cross-sectional view showing one example of the image-forming laminate of the present invention. The imaging laminate 10 shown in FIG. 1 comprises a carrier sheet 6, a barrier layer 3, and a heat-sensitive imaging layer 4 in this order. The image-forming laminate of the present invention may also have an overcoat layer 5 as shown in FIG.

[0014] In the present invention, as described above, the infrared absorbing dyes contained in the barrier layer and the thermosensitive image forming layer (the first infrared absorbing dye and the second infrared absorbing dye, respectively) are both compounds that have absorption at a wavelength of 1070 nm and have a mass absorption coefficient at a wavelength of 1070 nm of 50 L / (g cm) or more, and the barrier layer and the thermosensitive image forming layer further contain an infrared absorbing dye (a third infrared absorbing dye) that has absorption at a wavelength of 830 nm, thereby increasing the sensitivity of the thermosensitive image forming layer and improving the manufacturability of the image forming laminate. Although the details of this are not clear, the present inventors speculate as follows. First, the reason why the sensitivity of the heat-sensitive image forming layer is increased is believed to be that the absorption wavelength of the first infrared absorbing dye and the second infrared absorbing dye is 1070 nm, which makes it easier to apply a fiber laser. On the other hand, the manufacturability is believed to be due to the high crystallinity of the first infrared absorbing dye and the second infrared absorbing dye. Therefore, in the present invention, by using the third infrared absorbing dye having absorption at a wavelength of 830 nm in combination with the first infrared absorbing dye or the second infrared absorbing dye, it is possible to suppress crystallization of the first infrared absorbing dye and the second infrared absorbing dye, which is thought to have improved manufacturing suitability. The infrared absorbing dye will be described in detail below, and then the layer configuration of the image-forming laminate of the present invention will be described in detail.

[0015] [First infrared absorbing dye / second infrared absorbing dye] The first infrared absorbing dye contained in the barrier layer and the second infrared absorbing dye contained in the thermosensitive image forming layer are both compounds that have absorption at a wavelength of 1070 nm and have a mass absorption coefficient at a wavelength of 1070 nm of 50 L / (g cm) or more (hereinafter referred to as "specific dyes"). Moreover, the specific dye more preferably has a mass absorption coefficient of 50 to 200 L / (g·cm), and further preferably has a mass absorption coefficient of 50 to 100 L / (g·cm). Here, the mass absorption coefficient refers to a value calculated by the following method. First, 10 mg of the infrared absorbing dye to be measured is diluted with 1 L of methyl ethyl ketone to obtain a measurement solution. Next, the absorption spectrum of the obtained measurement solution is measured in the infrared absorption range (200 nm to 3300 nm) using a measuring device UH4150 manufactured by Hitachi High-Tech Science Corporation. Next, the mass absorption coefficient at a wavelength of 1070 nm is calculated from the obtained absorption spectrum (unit: L / g cm). Specifically, the transmittance T (%) of a solution with a specified concentration C (g / L) over a cell length L (cm) is measured, and the mass absorption coefficient k is calculated using the following formula. Mass absorption coefficient k=A / CL (unit: L / (g cm)) Absorbance A=-log 10 (T)

[0016] In the present invention, the specific dyes as the first infrared absorbing dye and the second infrared absorbing dye are preferably compounds represented by the following formula (1) because this increases the sensitivity of the heat-sensitive image forming layer. [ka]

[0017] In the above formula (1), R represents a monovalent organic group, and multiple R may be the same or different. In addition, in the above formula (1), X - represents a monovalent anion, and multiple X - may be the same or different from each other.

[0018] Examples of the monovalent organic group represented by R in the above formula (1) include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, -NR 11 R 12 (R 11 and R 1 2 each independently represents a hydrogen atom or a hydrocarbon group.) and the like, and these groups may further have a substituent. Examples of the alkyl group include linear or branched alkyl groups having 1 to 18 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a tert-pentyl group, and an n-hexyl group. Examples of the cycloalkyl group include monocyclic or polycyclic cycloalkyl groups having 3 to 20 carbon atoms, and specific examples thereof include a cyclopentyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclohexyl group, a cyclohexylmethyl group, and a cyclohexylethyl group. The aryl group may, for example, be an aryl group having 6 to 14 carbon atoms, and specific examples thereof include a phenyl group, a methylphenyl group, a tolyl group, a xylyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a pyrenyl group. Examples of the aralkyl group include aralkyl groups having 7 to 20 carbon atoms, and specific examples thereof include a benzyl group, a phenethyl group, a 2-phenylethan-2-yl group, and a naphthylmethyl group. Examples of the alkenyl group include alkenyl groups having 3 to 20 carbon atoms, and specific examples thereof include a vinyl group and an allyl group. R 11 and R 12 Examples of the hydrocarbon group represented by one embodiment of the formula (1) include the above alkyl groups and aryl groups.

[0019] X in the above formula (1) - The monovalent anion represented by is, for example, ClO4 - , PF6 - , BF4 - and the bis(trifluoromethanesulfonyl)imide anion represented by the following formula: Also, X - As the monovalent anion in the above formula (I), the anions described in paragraphs

[0016] to

[0023] of JP-A-2011-38007 can also be used. [ka]

[0020] [Third infrared absorbing dye] In the present invention, as described above, both the barrier layer and the heat-sensitive image-forming layer further contain a third infrared absorbing dye having absorption at a wavelength of 830 nm. Here, as the third infrared absorbing dye, a dye having absorption at a wavelength of 830 nm can be appropriately selected from known infrared absorbing dyes and used. For example, azo dyes, squarylium dyes, croconate dyes, triarylamine dyes, thiazolium dyes, indolium dyes, oxonol dyes, oxazolium dyes, cyanine dyes, merocyanine dyes, phthalocyanine dyes, indocyanine dyes, indotricarbocyanine dyes, oxatricarbocyanine dyes, thiocyanine dyes, thiatricarbocyanine dyes, merocyanine dyes, dyes, cryptocyanine dyes, naphthalocyanine dyes, polyaniline dyes, polypyrrole dyes, polythiophene dyes, chalcogenopyroarylidene and bi(chalcogenopyro)polymethine dyes, oxyindolizine dyes, pyrylium dyes, pyrazoline azo dyes, oxazine dyes, naphthoquinone dyes, anthraquinone dyes, quinoneimine dyes, methine dyes, arylmethine dyes, squaraine dyes, oxazole dyes, croconine dyes, porphyrin dyes, and substituted or ionic forms of any of these dye classes. The third infrared absorbing dye is preferably a cyanine dye, more preferably a closed-type cyanine dye, for the reason that the effect of the present invention is more excellent. An example of such a dye is IR-813 (p-toluenesulfonate) (manufactured by Tokyo Chemical Industry Co., Ltd.).

[0021] [Carrier sheet] The carrier sheet in the image-forming laminate of the present invention is not particularly limited, but is preferably a transparent polymer film, and may be a single layer or a laminate of two or more layers. Here, the term "transparent" in the present invention indicates that the transmittance of visible light is 60% or more, preferably 80% or more, and particularly preferably 90% or more. Examples of materials for polymer films include cellulose-based polymers; acrylic-based polymers having acrylic acid ester polymers such as polymethyl methacrylate and lactone ring-containing polymers; thermoplastic norbornene-based polymers; polycarbonate-based polymers; polyester-based polymers such as polyethylene terephthalate, polyethylene naphthalate, and fluorinated polyester polymers; styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers (AS resins); polyolefin-based polymers such as polyethylene, polypropylene, ethylene-propylene copolymers, and polybutadiene; vinyl chloride-based polymers; amide-based polymers such as nylon and aromatic polyamides; imide-based polymers; sulfone-based polymers; polyethersulfone-based polymers; polyetheretherketone-based polymers; polyphenylene sulfide-based polymers; vinylidene chloride-based polymers; vinyl alcohol-based polymers; vinyl butyral-based polymers; arylate-based polymers; polyoxymethylene-based polymers; epoxy-based polymers; or mixtures of these polymers.

[0022] In addition, the surface of the carrier sheet (the surface on which the barrier layer is formed) may be subjected to a release treatment to suppress adhesion of the barrier layer and improve the releasability of the carrier sheet. Examples of such a release treatment include a method of forming a release layer by applying a release agent to the surface of the carrier sheet. Examples of the release agent include silicone-based release agents and alkyl-based release agents.

[0023] The thickness of the carrier sheet is preferably 25 to 250 μm.

[0024] [Barrier Layer] The barrier layer of the image-forming laminate of the present invention is a layer containing the first infrared absorbing dye described above, and functions as an infrared ablation layer together with the heat-sensitive image-forming layer described below.

[0025] <Content of first infrared absorbing dye> The content of the first infrared absorbing dye contained in the barrier layer is preferably 2 to 75 mass %, more preferably 5 to 70 mass %, based on the mass of the barrier layer, i.e., the total mass of the solid contents of the composition used to form the barrier layer. <Content of the third infrared absorbing dye> The content of the third infrared absorbing dye contained in the barrier layer is preferably 2 to 75 mass % and more preferably 5 to 70 mass % relative to the mass of the barrier layer, i.e., the total mass of the solid contents of the composition used to form the barrier layer, because this provides better effects of the present invention. <Ratio of the content of the third infrared absorbing dye to the content of the first infrared absorbing dye> The ratio (mass ratio) of the content of the above-mentioned third infrared absorbing dye contained in the barrier layer to the content of the above-mentioned first infrared absorbing dye contained in the barrier layer is preferably 0.5 to 2, and more preferably 0.8 to 1.2, because the effects of the present invention are more excellent.

[0026] In the present invention, for the reason that the occurrence of blank spots in line drawings can be suppressed when the barrier layer is made into a flexographic printing plate, the content of a compound that has substantially no absorption in the wavelength region of 900 to 1200 nm and has absorption in the wavelength region of 300 to 400 nm (hereinafter also abbreviated as "UV absorbing impurities") in the barrier layer is preferably 0 mass % or more and less than 0.1 mass % relative to the mass of the barrier layer. Here, "substantially no absorption" means that the absorbance of a 1.0 g / L dichloromethane solution of a UV-absorbing impurity in a cell length of 1 cm is 5.0 or less, preferably 2.0 or less, and more preferably 0 to 1.0. In addition, it is preferable that the content of UV absorbing impurities is 0 mass %, that is, no UV absorbing impurities are contained.

[0027] <Thermal decomposable compounds> The barrier layer preferably contains a thermally decomposable compound as a binder. Examples of the thermally decomposable compound include ammonium nitrate, potassium nitrate, sodium nitrate, nitrocellulose, polyvinylpyrrolidone, azo compounds, diazo compounds, hydrazine derivatives, acrylic resins, metals and metal oxides. Among these, polymer compounds are preferred from the standpoint of solution coatability, and polyvinylpyrrolidone, nitrocellulose, and acrylic resins are more preferred. The content of the thermally decomposable compound is preferably 80 mass % or less, more preferably 15 to 60 mass %, based on the mass of the barrier layer, ie, the total mass of the solid content of the composition used for formation.

[0028] The thickness of the barrier layer is preferably 0.1 to 6 μm, and more preferably 0.2 to 3 μm.

[0029] [Heat-sensitive image-forming layer] The heat-sensitive image-forming layer of the image-forming laminate of the present invention is a layer containing an ultraviolet absorbing agent and the above-mentioned second infrared absorbing dye, and functions as an infrared ablation layer.

[0030] <Content of second infrared absorbing dye> The content of the second infrared absorbing dye contained in the thermosensitive image forming layer is preferably 2 to 75 mass % and more preferably 5 to 70 mass % based on the mass of the thermosensitive image forming layer, i.e., the total mass of the solid content of the composition used to form the layer. <Content of the third infrared absorbing dye> The content of the third infrared absorbing dye contained in the thermosensitive image forming layer is preferably 2 to 75 mass % and more preferably 5 to 70 mass % based on the mass of the thermosensitive image forming layer, i.e., the total mass of the solid content of the composition used for formation, because this provides a better effect of the present invention. <Ratio of the content of the third infrared absorbing dye to the content of the second infrared absorbing dye> The ratio (mass ratio) of the content of the third infrared absorbing dye contained in the thermosensitive image forming layer to the content of the second infrared absorbing dye contained in the thermosensitive image forming layer is preferably 0.5 to 2, and more preferably 0.8 to 1.2, for reasons of superior effects of the present invention.

[0031] <Ultraviolet absorbing agent> Suitable examples of the ultraviolet absorbing agent contained in the heat-sensitive image forming layer include compounds having absorption in the region of 300 nm to 400 nm. Specific examples of the compound include benzotriazole-based compounds, triazine-based compounds, benzophenone-based compounds, and carbon black. Specific examples of the compound include metal compounds such as iron powder, diamine metal complexes, dithiol metal complexes, phenolthiol metal complexes, mercaptophenol metal complexes, aryl aluminum metal salts, inorganic compounds containing crystal water, copper sulfate, chromium sulfide, and silicate compounds; and metal oxides such as titanium oxide, vanadium oxide, manganese oxide, iron oxide, cobalt oxide, and tungsten oxide. Of these, it is preferable to use a benzophenone compound or carbon black.

[0032] The content of the ultraviolet absorber is preferably 0.1 to 75% by mass, more preferably 1 to 50% by mass, based on the mass of the heat-sensitive image-forming layer, ie, the total mass of the solid content of the composition used for formation.

[0033] <Thermal decomposable compounds> The heat-sensitive image-forming layer preferably contains a heat-decomposable compound as a binder. The thermally decomposable compound is the same as that explained in the barrier layer above, and the preferred examples and content thereof are also the same.

[0034] The thickness of the heat-sensitive image forming layer is preferably from 0.1 to 6 μm, and more preferably from 0.5 to 3 μm.

[0035] [Overcoat Layer] As shown in FIG. 1, the image-forming laminate of the present invention may have an overcoat layer (hereinafter, also referred to as a "protective layer"). Examples of the overcoat layer include layers having properties such as preventing the occurrence of scratches in the heat-sensitive image forming layer, resistance to infrared ablation, and suppression of mass transfer between the mask and the photosensitive resin layer. Overcoat layers having such properties include, but are not limited to, those comprising a methacrylic acid copolymer (e.g., a copolymer of ethyl methacrylate and methacrylic acid) and one or more fluoropolymer particles dispersed therein, as described, for example, in U.S. Pat. No. 6,259,465 (Tutt et al.).

[0036] The overcoat layer preferably contains a water-soluble polymer. Here, the water-soluble polymer refers to a polymer that dissolves at least 1 g in 100 g of pure water at 70°C and does not precipitate even when a solution in which 1 g of the polymer is dissolved in 100 g of pure water at 70°C is cooled to 25°C. Examples of such water-soluble polymers include polyvinyl alcohol, modified polyvinyl alcohol, polyvinylpyrrolidone, water-soluble cellulose derivatives, polyethylene glycol, and poly(meth)acrylonitrile.

[0037] The thickness of the overcoat layer is preferably from 0.01 to 1 μm, and more preferably from 0.05 to 0.5 μm.

[0038] [Flexographic printing plate manufacturing method] The method for producing a flexographic printing plate of the present invention is a method for producing a flexographic printing plate having a non-image area and an image area, comprising the steps of: a mask forming step of forming an image on the heat-sensitive image forming layer of the image forming laminate of the present invention to form a mask; a lamination step of laminating the mask on a photosensitive resin layer of a flexographic printing plate precursor having a support and a photosensitive resin layer, the lamination step being performed after the mask formation step; an exposure step of exposing the photosensitive resin layer to light in an imagewise manner through the mask after the lamination step; a peeling step of peeling the mask from the photosensitive resin layer after the exposure step; After the peeling step, a developing step is performed in which a developer is used to develop the resist and form non-image areas and image areas.

[0039] [Mask formation process] The mask forming step is a step of forming an image on the thermosensitive image forming layer and forming a mask to be used in the exposure step described later. As described above, the barrier layer of the image forming laminate of the present invention functions as an infrared ablation layer together with the thermosensitive image forming layer, so that when an image is formed on the thermosensitive image forming layer, an image is also formed on the barrier layer at the same time. Here, when the heat-sensitive image-forming layer is irradiated with an infrared laser, heat is generated by the action of the second infrared absorbing dye, and the heat-decomposable compound is decomposed by the action of the generated heat, and the heat-sensitive image-forming layer is removed, i.e., laser ablated. Therefore, by selectively ablating the heat-sensitive image forming layer with a laser based on image data, an image mask capable of forming a latent image in the photosensitive resin layer can be obtained.

[0040] For infrared laser irradiation, an oscillation wavelength in the range of 750 nm to 3000 nm is used. Examples of such lasers include solid-state lasers such as ruby ​​lasers, alexandrite lasers, perovskite lasers, Nd-YAG lasers, and emerald glass lasers; semiconductor lasers such as InGaAsP, InGaAs, and GaAsAl; and dye lasers such as rhodamine dyes. Also, fiber lasers in which these light sources are amplified by fiber can be used. Of these, it is preferable to use an exposure light source having an oscillation wavelength of 900 to 1200 nm, and it is more preferable to use a fiber laser, because this increases the sensitivity of the heat-sensitive image-forming layer.

[0041] [Lamination process] The lamination step is a step of laminating the mask on the photosensitive resin layer of the flexographic printing plate precursor having a support and a photosensitive resin layer after the mask formation step.

[0042] <Flexographic printing plate precursor> The flexographic printing plate precursor used in the lamination step is not particularly limited as long as it has a support and a photosensitive resin layer, and any conventionally known flexographic printing plate precursor can be used as appropriate.

[0043] (Support) The material used for the support of the flexographic printing plate precursor is not particularly limited, but materials with high dimensional stability are preferably used, and examples thereof include metals such as steel, stainless steel, and aluminum; polyesters (e.g., PET (polyethylene terephthalate), PBT (polybutylene terephthalate), and PEN (polyethylene naphthalate)), PI (polyimide), polyamide, LCP (liquid crystal polymer), and PAN (polyacrylonitrile); plastic resins such as polyvinyl chloride; synthetic rubbers such as styrene-butadiene rubber; plastic resins reinforced with glass fibers (e.g., epoxy resins and phenolic resins); cloth, paper, and the like. From the viewpoints of dimensional stability and availability, the support is preferably a polymer film or cloth, more preferably a polymer film. The form of the support is determined depending on whether the polymer layer is in the form of a sheet or a sleeve.

[0044] As the cloth, a plain weave or twill weave fabric, various knitted fabrics, or nonwoven fabrics made of natural fibers such as cotton, hemp, silk, or wool, or synthetic fibers such as acetate, vinylon, vinylidene, polyvinyl chloride, acrylic, polypropylene, polyethylene, polyurethane, fluorine-based filaments, polychlor, rayon, nylon, polyamide, or polyester can be used. Examples of polymer films include films formed from various polymers such as polyester (e.g., PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PEN (polyethylene naphthalate)), PI (polyimide), polyamide, LCP (liquid crystal polymer), PAN (polyacrylonitrile); plastic resins such as polyvinyl chloride; synthetic rubbers such as styrene-butadiene rubber; and plastic resins reinforced with glass fibers (epoxy resins, phenolic resins, etc.). Among these, polyester films are preferred from the viewpoint of dimensional stability, etc. Examples of the polyester film include a PET film, a PBT film, and a PEN film. From the viewpoint of dimensional stability, a PET (polyethylene terephthalate) film is preferred.

[0045] The thickness of the support is not particularly limited, but from the viewpoints of dimensional stability and handleability, it is preferably from 5 to 3000 μm, more preferably from 50 to 2000 μm, and even more preferably from 100 to 1000 μm.

[0046] (Photosensitive resin layer) The photosensitive resin layer of the flexographic printing plate precursor is not particularly limited, and can be formed using a conventionally known photosensitive resin composition, for example, a resin composition containing a water-dispersible latex, rubber, a photopolymerizable monomer, a photopolymerization initiator, a surfactant, etc.

[0047] In the present invention, because the occurrence of blank spots in line drawings can be suppressed when the resulting flexographic printing plate is produced, it is preferred that the photosensitive resin layer contains a monomer, a polymerization initiator, a base polymer, and water-dispersible particles, the water-dispersible particles have carbon-carbon double bonds, and the amount of carbon-carbon double bonds on the surface of the water-dispersible particles is 21 or less. This is because, when the photosensitive resin layer is formed, fusion of the water-dispersible particles that may occur during coating and drying is suppressed, so that even if an unwanted image is formed due to the above-mentioned weakly exposed portion, it can be removed by development. Such a photosensitive resin layer is described in paragraphs

[0016] to

[0044] of International Publication No. 2020 / 158778. The descriptions in the above documents are incorporated herein by reference.

[0048] The thickness of the photosensitive resin layer is preferably 0.2 to 6 mm.

[0049] <Lamination method> The method for laminating the mask on the photosensitive resin layer of the flexographic printing plate precursor is not particularly limited, and examples thereof include a method of pressure bonding using an adhesive, and a method of bonding by passing the mask through a heated roll while sandwiching a heat-meltable adhesive film therebetween (thermal lamination). The adhesive may be, for example, a pressure-sensitive adhesive, and specifically, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferably used.

[0050] [Exposure process] The exposure process is a process of exposing the photosensitive resin layer in an imagewise manner through the mask obtained in the mask formation process. By irradiating the photosensitive resin layer with ultraviolet light in an imagewise manner, crosslinking and / or polymerization can be induced in the areas irradiated with ultraviolet light, thereby enabling hardening.

[0051] [Peeling process] The peeling step is a step of peeling the mask from the photosensitive resin layer after the exposure step. The method for peeling the mask from the photosensitive resin layer is not particularly limited, and the mask can be peeled off by, for example, pulling or the like.

[0052] [Development process] The developing step is a step in which development is carried out using a developer to form non-image areas and image areas.

[0053] The developer used in the developing step is not particularly limited, and any conventionally known developer can be used, but from the viewpoint of reducing the environmental load, it is preferable to use a developer containing 50% by mass or more of water (hereinafter, also abbreviated as "aqueous developer"). The developer may be either an aqueous solution or a suspension (for example, an aqueous dispersion). The content of water in the aqueous developer is preferably from 80 to 99.99% by mass, and more preferably from 90 to 99.9% by mass, based on the total mass of the aqueous developer.

[0054] In the present invention, the aqueous developer preferably contains a surfactant represented by the following formula (2). [ka]

[0055] In the above formula (2), A represents an alkylene group having 2 to 4 carbon atoms, R 1 represents a hydrogen atom or a substituent, and n represents an integer of 1 to 100. When n is an integer of 2 to 100, multiple As may be the same or different.

[0056] In the above formula (2), A represents an alkylene group having 2 to 4 carbon atoms, preferably an alkylene group having 2 or 3 carbon atoms, and more preferably an ethylene group or an n-propylene group.

[0057] R in the above formula (2) 1Examples of the substituent represented by one embodiment of the formula (1) include an alkyl group, an alkoxy group, an alkylcarbonyl group, an alkoxycarbonyl group, an alkylcarbonyloxy group, an alkylamino group, a dialkylamino group, an alkylamide group, an alkenyl group, an alkynyl group, a halogen atom, a cyano group, a nitro group, an alkylthiol group, and an N-alkylcarbamate group. Among these, an alkyl group is preferable. The alkyl group, which is a suitable example of the substituent, is, for example, preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, a propyl group, and an n-butyl group. In addition, R in the above formula (2) 1 represents a hydrogen atom or a substituent, but is preferably a hydrogen atom because this improves the dispersibility of development residue.

[0058] In the above formula (2), n represents an integer of 1 to 100. In order to improve the dispersibility of development residue, n is preferably an integer of 1 to 30, more preferably an integer of 5 to 20, and even more preferably an integer of 5 to 15.

[0059] [Rinsing process] The method for producing a flexographic printing plate of the present invention preferably includes, after the developing step, a rinsing step of rinsing the surfaces of the non-image areas and image areas formed in the developing step with water.

[0060] Examples of the rinsing means in the rinsing step include a method of washing with tap water, a method of spraying high-pressure water, and a method of brushing the surfaces of the non-image areas and the image areas mainly in the presence of water using a batch-type or conveying-type brush-type washing machine known as a developing machine for flexographic printing plates. EXAMPLES

[0061] The present invention will be described in more detail below with reference to examples. The materials, amounts, ratios, processing contents, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples.

[0062] [Example 1] [Preparation of laminate for infrared ablation] A coating solution for the barrier layer was obtained by adding 51.1 parts by mass of acetone and 41.8 parts by mass of cyclopentanone to 1.3 parts by mass of the third infrared absorbing dye (IR-813, p-toluenesulfonic acid, manufactured by Tokyo Chemical Industry Co., Ltd.), 1.3 parts by mass of the first infrared absorbing dye (CIR-RL, manufactured by Nippon Carlit Co., Ltd.), and 4.5 parts by mass of nitrocellulose (H1 / 8, manufactured by Taihei Chemical Products Co., Ltd.), and stirring until homogenous. Next, the barrier layer coating solution was applied to one side of a 125 μm-thick PET film [carrier sheet] using a bar coater so that the thickness after drying would be 0.4 μm, and then the coating solution was dried for 2 minutes in an oven set at 90° C. to obtain a barrier layer. A coating solution for a thermosensitive image forming layer was obtained by adding 90.5 parts by mass of methyl ethyl ketone to 1.2 parts by mass of a third infrared absorbing dye (IR-813, p-toluenesulfonic acid, manufactured by Tokyo Chemical Industry Co., Ltd.), 1.2 parts by mass of a second infrared absorbing dye (CIR-RL, manufactured by Japan Carlit Co., Ltd.), 1.3 parts by mass of 2,2',4,4'-tetrahydroxybenzophenone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 1.4 parts by mass of curcumin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 4.3 parts by mass of nitrocellulose (H1 / 8, manufactured by Taihei Chemical Products Co., Ltd.) and stirring until homogenous. Next, a coating liquid for a heat-sensitive image-forming layer was applied to the upper surface of the barrier layer using a bar coater so that the thickness after drying would be 1.4 μm, and then dried for 2 minutes in an oven set at 90° C. to obtain a heat-sensitive image-forming layer. Water-soluble binder (PVA-205, manufactured by Kuraray Co., Ltd.) 57 parts by mass, polytetrafluoroethylene (PTFE) water-dispersed particles (Fluon AD915E, manufactured by AGC Co., Ltd.) 13 parts by mass, Polyether-modified polydimethylsiloxane (Byk-333, Byk Chemie) 22 parts by mass, surfactant (Surfynol FS-80, Air Products and Chemicals) 7 parts by mass 0.5 parts by mass were mixed and then diluted with a water / ethanol = 4:1 mixture to a solids content of 0.3% to obtain a coating liquid for the protective layer. Next, the protective layer coating liquid was applied to the upper surface of the heat-sensitive image-forming layer using a bar coater so that the thickness after drying would be 0.1 μm, and then dried for 2 minutes in an oven set at 90° C. to obtain a heat-sensitive image-forming layer (hereinafter also referred to as a "laminate for infrared ablation") having a carrier sheet, a barrier layer, a heat-sensitive image-forming layer, and a protective layer in that order. The first infrared absorbing dye and the second infrared absorbing dye, CIR-RL (manufactured by Nippon Carlit Co., Ltd.), are compounds that have absorption at a wavelength of 1070 nm, and the mass absorption coefficient at a wavelength of 1070 nm was 66.2 L / (g cm), as shown in the following Tables 1 and 2. The infrared absorbing dye, CIR-RL (manufactured by Nippon Carlit Co., Ltd.), is a compound represented by the above formula (1). The third infrared absorbing dye, IR-813 (p-toluenesulfonate) (Tokyo Chemical Industry Co., Ltd.), was a compound having absorption at a wavelength of 830 nm.

[0063] [Examples 2 to 3 and Comparative Examples 1 to 3] A laminate for infrared ablation was prepared according to the same procedure as in Example 1, except that the type and content (mass%) of each component in the barrier layer and the thermosensitive image forming layer were changed as shown in Tables 1 and 2 below. The ultraviolet absorbent contained in the barrier layers of Examples 2, 3, and Comparative Example 3 is 2,2',4,4'-tetrahydroxybenzophenone, as shown in Table 1 below. This is a compound that has substantially no absorption in the wavelength region of 900 to 1200 nm, and has absorption in the wavelength region of 300 to 400 nm.

[0064] [Comparative Example 4] A laminate for infrared ablation was prepared in the same manner as in Example 1, except that the laminate for infrared ablation was changed to the following: The components of the barrier layer and the thermosensitive image forming layer are also shown in Tables 1 and 2 below. [Preparation of laminate for infrared ablation] To 50 parts by mass of acrylic resin (Hiper M5000, manufactured by Negami Chemical Industries Co., Ltd.), 50 parts by mass of elastomer (Nipol DN101, NBR, manufactured by Zeon Corporation), and 100 parts by mass of carbon black (MA8, manufactured by Mitsubishi Chemical Corporation) as an infrared absorbing pigment, 600 parts by mass of methyl isobutyl ketone was added and mixed with a blade stirrer. The resulting mixture was dispersed with a paint shaker, and further methyl isobutyl ketone was added so that the solids content was 15% by mass, thereby obtaining a polymer / carbon black dispersion (coating liquid for a heat-sensitive image forming layer). Next, the coating liquid for the heat-sensitive image forming layer was applied to one side of a 125 μm thick PET film [carrier sheet] using a bar coater so that the thickness after drying would be 1.0 μm, and then dried for 1 minute in an oven set at 140° C. to produce a laminate for an infrared ablation layer having a carrier sheet and a heat-sensitive image forming layer but no barrier layer. The mass absorption coefficient of the infrared absorbing pigment carbon black (MA8, manufactured by Mitsubishi Chemical Corporation) at a wavelength of 1070 nm was 49 L / (g cm), as shown in Table 2 below.

[0065] [Table 1]

[0066] [Table 2]

[0067] [evaluation] 〔sensitivity〕 For the laminates for infrared ablation layers prepared in Examples 1 to 3 and Comparative Examples 1 and 4, IR was applied to the heat-sensitive image forming layer using a CDI Spark2530 manufactured by ESKO. The drawing was carried out. In addition, the laminates for infrared ablation layers prepared in Comparative Examples 2 and 3 were thermally imaged using a Trendsetter (registered trademark) 800 Imager (Kodak SQUARESPOT head, 830 nm exposure wavelength). The active imaging layer was then subjected to IR imaging. The light intensity used for drawing is 0 to 5.0 J / cm 2 The amount of light when the Dmin after printing was 0.07 or less was evaluated as the sensitivity. The results are shown in Table 3 below.

[0068] [White areas in line drawings] Infrared ablation layer created using ESKO CDI Spark2530 An image pattern was formed in the heat-sensitive image forming layer included in the laminate for use to prepare a mask. Next, the substrate side of a commercially available water-developable flexographic original plate (FW-A, Fujifilm Corporation) was exposed for 15 seconds (back exposure) from a distance of 15 cm using an exposure device equipped with 15 40 W fluorescent lamps. Next, the carrier sheet of the flexographic master plate was peeled off to expose the photosensitive resin layer, which was then bonded to the protective layer side of the mask. Next, the carrier sheet side of the attached mask was exposed for 8 minutes (main exposure) from a distance of 15 cm using the exposure device. After that, the mask was peeled off, and the film was exposed to a 1000-milligram film containing 0.5% sodium carbonate and a surfactant (Paionin D-6120, Takemoto Oil Co., Ltd.) (surfactant represented by the above formula (2)) (A: -CH2CH2- (ethylene group), R 1 The film was developed for 10 minutes in a brush-type washing machine (liquid temperature 50° C.) containing an aqueous developer adjusted to a concentration of 1% (n: hydrogen atom, n: 20). Thereafter, the coating was dried with hot air at 60° C. until all moisture was removed. Thereafter, the coating was exposed (post-exposed) for 8 minutes from above the photosensitive layer at a distance of 15 cm using the exposure device to prepare a flexographic printing plate. The flexographic printing plate was used to print, and the white spots of a 200 μm-wide thin line were evaluated according to the following criteria. The results are shown in Table 3 below. <Evaluation criteria> A: No white spots. B: White spots are observed with a magnifying glass, but not visible to the naked eye. C: White spots were observed visually.

[0069] [Manufacturing suitability] The laminate for infrared ablation layer thus prepared was stored for 24 hours in an environment of 50° C. and 70% relative humidity, after which the surface of the laminate for infrared ablation layer was observed and evaluated according to the following criteria. The results are shown in Table 3 below. A: No crystal precipitate B: Crystalline precipitates present

[0070] [Table 3]

[0071] From the results shown in Tables 1 to 3 above, it was found that when the barrier layer and the heat-sensitive image-forming layer did not contain the third infrared absorbing dye, the manufacturability was poor (Comparative Example 1). It was found that when the barrier layer did not contain the first infrared absorbing dye and the heat-sensitive imaging layer did not contain the first infrared absorbing dye, the sensitivity of the heat-sensitive imaging layer was inferior (Comparative Examples 2 and 3). In addition, when a thermosensitive image forming layer containing an infrared absorbing pigment that does not fall under the category of an infrared absorbing dye was used without providing a barrier layer, it was found that the sensitivity of the thermosensitive image forming layer was further deteriorated, and white voids occurred in the line drawings when the layer was made into a flexographic printing plate (Comparative Example 4). In contrast, it was found that when the barrier layer contains a first infrared absorbing dye and a third infrared absorbing dye, and the heat-sensitive image-forming layer contains a second infrared absorbing dye and a third infrared absorbing dye, the sensitivity of the heat-sensitive image-forming layer is increased and the manufacturability of the image-forming laminate is also improved (Examples 1 to 3). In particular, by comparing Examples 1 and 2 with Example 3, it was found that when the content of the compound in the barrier layer that has substantially no absorption in the wavelength region of 900 to 1200 nm and has absorption in the wavelength region of 300 to 400 nm is 0% by mass or more and less than 0.1% by mass relative to the mass of the barrier layer, the occurrence of blank spots in the line drawing can be suppressed when the barrier layer is made into a flexographic printing plate. Among these, Example 1, in which the content of the UV-absorbing impurities in the barrier layer is 0.05% by mass or less relative to the mass of the barrier layer, further suppressed the occurrence of blank spots. [Explanation of symbols]

[0072] 3. Barrier layer 4. Heat-sensitive image-forming layer 5 Overcoat layer 6 Carrier Sheet 10 Image forming laminate

Claims

1. 1. An imaging laminate for forming a mask for use in making flexographic printing plates, comprising: a carrier sheet, a barrier layer, and a heat-sensitive image-forming layer, in that order; the barrier layer contains a first infrared absorbing dye; the heat-sensitive imaging layer contains an ultraviolet absorbing agent and a second infrared absorbing dye; the first infrared absorbing dye and the second infrared absorbing dye are both compounds that have absorption at a wavelength of 1070 nm and have a mass absorption coefficient at a wavelength of 1070 nm of 50 L / (g cm) or more; an imaging laminate, wherein both the barrier layer and the heat-sensitive imaging layer contain a third infrared absorbing dye having absorption at a wavelength of 830 nm;

2. 2. The image-forming laminate according to claim 1, wherein the content of the compound in the barrier layer that has substantially no absorption in a wavelength region of 900 to 1,200 nm and has absorption in a wavelength region of 300 to 400 nm is 0% by mass or more and less than 0.1% by mass with respect to the mass of the barrier layer.

3. 3. The image-forming laminate according to claim 1, wherein the first infrared absorbing dye and the second infrared absorbing dye are both compounds represented by the following formula (1): 【Chemistry 1】 Here, in the formula (1), R represents a monovalent organic group, and multiple R may be the same or different. X － represents a monovalent anion, and a plurality of X － may be the same or different from each other.

4. 1. A method for producing a flexographic printing plate having non-image and image areas, comprising the steps of: a mask forming step of forming an image on the thermosensitive image forming layer of the image forming laminate according to any one of claims 1 to 3 to form a mask; a lamination step of laminating the mask on the photosensitive resin layer of a flexographic printing plate precursor having a support and a photosensitive resin layer after the mask formation step; an exposure step of exposing the photosensitive resin layer to light in an imagewise manner through the mask after the lamination step; a peeling step of peeling the mask from the photosensitive resin layer after the exposure step; A method for producing a flexographic printing plate, comprising a developing step of developing the exposed area with a developer to form non-image areas and image areas after the peeling step.

5. the photosensitive resin layer contains a monomer, a polymerization initiator, a base polymer, and water-dispersible particles; The water-dispersible particles have a carbon-carbon double bond, The method for producing a flexographic printing plate according to claim 4, wherein the number of carbon-carbon double bonds on the surface of the water-dispersible particles is 21 or less.

6. The method for producing a flexographic printing plate according to claim 4 or 5, wherein the developer contains 50% by mass or more of water.

7. The method for producing a flexographic printing plate according to any one of claims 4 to 6, wherein the developer contains a surfactant represented by the following formula (2): 【Chemistry 2】 Here, in the formula (2), A represents an alkylene group having 2 to 4 carbon atoms; R １ represents a hydrogen atom or a substituent, and n represents an integer of 1 to 100. When n is an integer of 2 to 100, multiple As may be the same or different.

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