Method for manufacturing flexographic printing plate and printing method

Abstract

A method for manufacturing a flexographic printing plate comprises a developing step of supplying an organic solvent-based developer to a surface of a flexographic printing original plate having at least a support, a photosensitive resin composition layer and an infrared ablation layer stacked in sequence, and abrading the surface of the plate with a brush, wherein the organic solvent-based developer contains 0.1% by mass or more and 10.0% by mass or less of a polymer gel.

Description

Technical Field

[0001] The present invention relates to a method for producing a flexographic printing plate and a printing method. Background Art

[0002] Flexographic printing is a type of relief printing. The material of the flexographic printing plate uses soft materials such as rubber and synthetic resin. Therefore, it has the advantage of being applicable to various printed objects.

[0003] As methods for producing flexographic printing plates used in flexographic printing, the following methods have been known: a method of making a plate using a negative film; and a method of using computer-to-plate technology (hereinafter referred to as CTP technology) in which information processed by a computer is directly drawn on a printing plate to produce a relief.

[0004] In the method using the aforementioned CTP technology, no film manufacturing process is required, which can reduce material costs and the time required to manufacture the film. Therefore, in recent years, the method using CTP technology has gradually become the mainstream as a method for manufacturing flexographic printing plates.

[0005] When using CTP technology, as a flexographic printing plate original (hereinafter sometimes referred to as "flexographic printing original"), an original plate in which at least a photosensitive resin composition layer and an infrared ablation layer are sequentially laminated on a support such as PET (polyethylene terephthalate) is generally used.

[0006] The production of a flexographic printing plate using the CTP technique is performed, for example, as follows.

[0007] First, the entire surface of the photosensitive resin composition layer is irradiated with ultraviolet light through a support such as PET constituting the above-mentioned flexographic printing original plate to perform back exposure, thereby providing a uniform cured layer. Next, the infrared ablation layer on the photosensitive resin composition layer is irradiated with laser for drawing, thereby removing a portion of the infrared ablation layer and preparing an image mask. Furthermore, the photosensitive resin composition layer is irradiated with ultraviolet light through the above-mentioned image mask for relief exposure, so that the photosensitive resin composition at the location where the infrared ablation layer is removed is photocured. Thereafter, a development step is performed to remove the unexposed portion of the photosensitive resin composition layer, that is, the portion that has not been photocured, to form a relief image as a desired image, thereby obtaining a flexographic printing plate.

[0008] For the aforementioned development process, the following methods are proposed: a solvent development method using an organic solvent-based developer to dissolve the photosensitive resin composition in the unexposed portion; and a water development method using water containing a surfactant to cause the photosensitive resin composition in the unexposed portion to swell and peel off. In particular, the solvent development method has a fast development speed and is widely used.

[0009] For example, Patent Document 1 discloses a technique for stabilizing developability by maintaining the temperature of a developer within a predetermined range.

[0010] In addition, Patent Document 2 discloses a developer that suppresses odor and maintains a development speed and development quality.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent Application Publication No. 2018-116109

[0014] Patent Document 2: International Publication No. 2011 / 025523 Summary of the invention

[0015] Problem that the invention aims to solve

[0016] However, the above conventionally proposed technologies have not studied the dimensional accuracy of flexographic printing plates, which is directly related to printing performance, and thus have the problem that there is room for further improvement.

[0017] Therefore, in view of the above-mentioned problems of the prior art, an object of the present invention is to provide a method for producing a flexographic printing plate capable of maintaining a high development speed, improving the productivity of the development step, and obtaining a flexographic printing plate having excellent dimensional stability and excellent printing characteristics.

[0018] Solutions for solving problems

[0019] The present inventors conducted intensive research to solve the above-mentioned problems and found that the problems of the prior art can be solved by implementing a development process in which a predetermined organic solvent-based developer is supplied to the surface of a flexographic printing plate while the surface is abraded with a brush, thereby completing the present invention.

[0020] That is, the present invention is as follows.

[0021] [1] A method for producing a flexographic printing plate, comprising a developing step of supplying an organic solvent-based developer to a surface of a flexographic printing plate having at least a support, a photosensitive resin composition layer, and an infrared ablative layer laminated in this order and abrading the surface with a brush,

[0022] The organic solvent-based developer contains 0.1% by mass or more and 10.0% by mass or less of a polymer gel.

[0023] [2] The method for producing a flexographic printing plate according to [1], wherein the absolute value of the difference between the solubility parameter (SP value) of the organic solvent in the organic solvent-based developer and the solubility parameter (SP value) of the polymer gel is 0.5 (cal / cm 3 ) 1 / 2 Above and 4.0(cal / cm 3 ) 1 / 2 the following.

[0024] [3] The method for producing a flexographic printing plate according to [1] or [2], wherein the polymer gel is particles having a number average particle size of 40 nm to 400 nm.

[0025] [4] The method for producing a flexographic printing plate according to any one of [1] to [3] above, wherein the photosensitive resin composition layer contains a thermoplastic elastomer.

[0026] [5] The method for producing a flexographic printing plate according to any one of [1] to [4] above, wherein the photosensitive resin composition layer contains a thermoplastic elastomer and polymer particles.

[0027] [6] The method for producing a flexographic printing plate according to [5] above, wherein the photosensitive resin composition layer has a dispersed phase and a continuous phase,

[0028] The aforementioned thermoplastic elastomer and the aforementioned polymer particles form the aforementioned continuous phase and the aforementioned dispersed phase.

[0029] [7] The method for producing a flexographic printing plate according to [5] or [6], wherein the absolute value of the difference between the solubility parameter (SP value) of the thermoplastic elastomer and the solubility parameter (SP value) of the polymer particles is 0.1 (cal / cm 3 ) 1 / 2 Above and 2.0(cal / cm 3 ) 1 / 2 the following.

[0030] [8] The method for producing a flexographic printing plate according to any one of [1] to [7], wherein the organic solvent-based developer contains alcohols and one or more selected from the group consisting of fatty acid esters, hydrocarbons, and chlorinated organic solvents.

[0031] [9] A printing method comprising the following steps:

[0032] A flexographic printing plate obtained by the method for producing a flexographic printing plate according to any one of [1] to [8] above,

[0033] The process of printing is carried out using the above-mentioned flexographic printing plate.

[0034] Effects of the Invention

[0035] According to the present invention, there can be provided a method for producing a flexographic printing plate having a high development speed, improved productivity in a development step, excellent dimensional stability, and excellent printing characteristics. DETAILED DESCRIPTION

[0036] Hereinafter, an embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. However, the present embodiment below is an example for explaining the present invention and does not limit the present invention to the following contents.

[0037] The present invention can be implemented with appropriate modifications within the scope of the present invention.

[0038] [Method for producing flexographic printing plate]

[0039] The method for producing a flexographic printing plate of the present embodiment includes a developing step of rubbing the surface of a flexographic printing original plate having at least a support, a photosensitive resin composition layer, and an infrared ablative layer laminated in this order with a brush while supplying an organic solvent-based developer to the surface.

[0040] The organic solvent-based developer contains 0.1% by mass or more and 10.0% by mass or less of a polymer gel.

[0041] According to the method for producing a flexographic printing plate of the present embodiment, it is possible to maintain a high development speed, improve the productivity of the development step, and obtain a flexographic printing plate having excellent dimensional stability and excellent printing characteristics.

[0042] As a method for manufacturing the flexible printing plate of the present embodiment, there can be listed, for example, a method having the following steps: a back exposure step of irradiating ultraviolet rays from the support side of the flexible printing original plate; an infrared irradiation step of irradiating the infrared ablation layer with infrared rays to draw a pattern; a relief exposure step of irradiating the photosensitive resin composition layer with ultraviolet rays using the infrared ablation layer drawing the pattern as a mask to perform relief exposure; and a development step of removing the unexposed portions of the infrared ablation layer and the photosensitive resin composition layer.

[0043] Hereinafter, each step will be described in detail.

[0044] (Back exposure process)

[0045] First, in the back exposure step, ultraviolet light exposure is applied to the entire surface through the support of the flexographic printing plate (back exposure) to cure the photosensitive resin composition layer to form a thin and uniform cured layer (back). It should be noted that the aforementioned cured layer (back) is a portion included in the cured photosensitive resin composition layer formed in the relief exposure step.

[0046] The exposure method at this time is not particularly limited, and the exposure can be performed using a known irradiation means.

[0047] The light source of ultraviolet rays is not limited to the following light sources, and examples thereof include low-pressure mercury lamps, high-pressure mercury lamps, ultrahigh-pressure mercury lamps, metal halide lamps, xenon lamps, zirconium lamps, carbon arc lamps, and ultraviolet fluorescent lamps.

[0048] It should be noted that the back exposure step may be performed before the infrared irradiation step described later, or the back exposure step and the relief exposure step described later may be performed simultaneously.

[0049] (Infrared irradiation process)

[0050] In the infrared irradiation step, the infrared ablation layer on the photosensitive resin composition layer is laser drawn, i.e., laser ablated, to produce a negative pattern. When the flexographic printing original has a cover film on the infrared ablation layer, the cover film is first peeled off before irradiating the infrared ray. Thereafter, the infrared ablation layer pattern is irradiated with infrared rays to decompose the resin in the infrared irradiated portion and draw the pattern. Thus, a mask of the infrared ablation layer is formed on the photosensitive resin composition layer.

[0051] In the laser drawing, an infrared laser can be used, and as the infrared laser, a laser with a wavelength of 750 to 2000 nm is preferred. As the infrared laser with such a wavelength, semiconductor lasers of 750 to 880 nm and Nd-YAG lasers of 1060 nm are generally used.

[0052] (Relief exposure process)

[0053] In the relief exposure step, the infrared ablation layer formed with the negative pattern is used as a mask to irradiate with ultraviolet rays, and the photosensitive resin composition layer is image-exposed (relief exposure) to form a cured photosensitive resin composition layer. It should be noted that, when there is an intermediate layer described later between the photosensitive resin composition layer and the infrared ablation layer, the photosensitive resin composition layer is relief-exposed via the intermediate layer.

[0054] At this time, the light passing through the mask promotes the curing reaction of the photosensitive resin composition layer, and the pattern formed on the infrared ablation layer is reversed and transferred to the photosensitive resin composition layer. It should be noted that the entire surface of the flexographic printing plate can be irradiated with ultraviolet rays.

[0055] Regarding the exposure from the infrared ablation layer side (relief exposure) and the exposure from the support film side (back exposure), either one may be performed first, or both may be performed simultaneously.

[0056] Examples of the exposure light source include a high-pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, and a xenon lamp.

[0057] (Development Process)

[0058] In the development step, the infrared ablation layer and the unexposed portion of the photosensitive resin composition layer are removed.

[0059] It should be noted that, when the intermediate layer is present, the intermediate layer is also removed.

[0060] In the development step of the method for manufacturing a flexographic printing plate of the present embodiment, an organic solvent-based developer is supplied to the surface of the flexographic printing plate while the surface is brushed with a brush. The brushing with a brush is not limited to the following brushing, and examples thereof include brushing by rotation of a roller brush, surface rotation of a flat brush, or reciprocating motion.

[0061] <Organic Solvent-Based Developer>

[0062] The organic solvent-based developer used in the development step refers to a developer containing an organic solvent.

[0063] The organic solvent is not limited to the following organic solvents, and various organic solvents may be listed, such as chlorine-based organic solvents such as 1,1,1-trichloroethane and tetrachloroethylene; ester solvents such as heptyl acetate and 3-methoxybutyl acetate; and hydrocarbon solvents such as petroleum fractions, toluene and decalin.

[0064] In addition, in the organic solvent-based developer used in the development process, it is preferred that the organic solvent contains one or more selected from the group consisting of fatty acid esters, hydrocarbons, and chlorine-based organic solvents. From the viewpoint of easily dissolving or swelling the various raw materials contained in the flexible printing original plate and developing them, it is further preferred that the organic solvent is formed by alcohols.

[0065] Furthermore, as the organic solvent-based developer used in the development process, it is preferred to use a developer that is a mixture of alcohols such as 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, and benzyl alcohol in various organic solvents such as the aforementioned fatty acid esters, hydrocarbons, or chlorine-based organic solvents.

[0066] Specifically, "Cylosol" (trade name, manufactured by DUPONT SPECIALTY PRODUCTS), "SOLVIT" (trade name, manufactured by Nippon MacDermid Co., Ltd.), and the like can be used.

[0067] In the entire organic solvent-based developer, the content of the organic solvent is preferably 50% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 80% by mass or more, from the viewpoint of development speed.

[0068] [Polymer gel in organic solvent-based developer]

[0069] In addition, from the perspective of ensuring a fast development speed and obtaining high dimensional accuracy of the flexographic printing plate, the aforementioned organic solvent-based developer used in the manufacturing method of the flexographic printing plate of this embodiment contains a polymer gel in an amount of greater than 0.1 mass % and less than 10 mass % relative to the total amount of the aforementioned organic solvent-based developer.

[0070] The content of the polymer gel is preferably 0.5% by mass or more, more preferably 0.7% by mass or more. The content of the polymer gel is preferably 5.0% by mass or less, more preferably 3.0% by mass or less.

[0071] As the polymer gel, it is preferable to use a polymer described later.

[0072] The polymer gel used in this embodiment does not dissolve even in an organic solvent-based developer, and exists in a state of being dispersed in the aforementioned organic solvent-based developer. Thus, it is possible to achieve both an increase in development speed and high dimensional accuracy. This is because: the polymer gel acts like an abrasive during development, thereby increasing the development speed, and by containing an organic solvent-based developer inside the polymer gel, the hardness is reduced, and the plate surface is not damaged, and high dimensional accuracy can be achieved.

[0073] As an indicator of the polymer gel not being dissolved in an organic solvent-based developer, the toluene gel fraction can be cited. In the polymer gel used in the present embodiment, the toluene gel fraction is preferably 50% or more and 100% or less. It is more preferably 60% or more and 100% or less, and further preferably 85% or more and 100% or less.

[0074] Here, the toluene gel fraction of the polymer gel is determined as follows.

[0075] 0.5 g of the polymer gel was taken and immersed in 30 mL of toluene at 25° C. and shaken for 3 hours using an oscillator. Afterwards, it was filtered using a 320 SUS mesh, and the non-passing components were dried at 130° C. for 1 hour. The mass fraction (%) obtained by dividing the mass of the dried component by 0.5 (g) was taken as the toluene gel fraction.

[0076] The polymer gel in the organic solvent-based developer can be removed by adding methanol to the organic solvent-based developer to precipitate the resin component and then drying the supernatant.

[0077] The toluene gel fraction of the polymer gel can be controlled by a known method, for example, by adjusting the amount of a chain transfer agent used when synthesizing the polymer gel, thereby being controlled within the above numerical range.

[0078] Examples of methods for producing the polymer gel include a method of synthesizing by various polymerization methods such as suspension polymerization and emulsion polymerization, and a method of producing by mechanochemistry.

[0079] The polymer constituting the aforementioned high molecular gel is not limited to the following polymers, and examples thereof include polymers having a butadiene skeleton, such as polybutadiene, acrylonitrile-butadiene copolymers, styrene-butadiene copolymers, and (meth)acrylate-butadiene copolymers; polymers having an isoprene skeleton, such as polyisoprene and polychloroprene; polymers obtained by further polymerizing a monomer having a carboxyl group and / or a hydroxyl group to the aforementioned polymer having a butadiene skeleton or an isoprene skeleton; polymers obtained by further polymerizing (meth)acrylate to the aforementioned polymer having a butadiene skeleton or an isoprene skeleton; polymers obtained by further polymerizing (meth)acrylate and a monomer having a carboxyl group and / or a hydroxyl group to the aforementioned polymer having a butadiene skeleton or an isoprene skeleton; polyurethane, vinyl pyridine polymer, butyl polymer, polysulfide rubber polymer, acrylate polymer, and natural rubber.

[0080] The polymer gel used in the present embodiment preferably has a number average particle diameter of 40 nm to 200 nm, more preferably 50 nm to 180 nm, and even more preferably 60 nm to 170 nm.

[0081] The number average particle size of the polymer gel is preferably 40 nm or more from the viewpoint of maintaining a high development speed, and is preferably 200 nm or less from the viewpoint of producing a flexographic printing plate with excellent reproducibility.

[0082] The number average particle size of the polymer gel in the organic solvent-based developer can be measured using a dynamic light scattering apparatus and can be controlled to fall within the above numerical range by appropriately setting the synthesis temperature and synthesis time of the polymer gel.

[0083] [Solubility parameters of organic solvent and polymer gel in organic solvent-based developer]

[0084] In addition, from the viewpoint of obtaining a fast development speed, the solubility parameter (SP value) of the organic solvent in the organic solvent-based developer used in the present embodiment is preferably 8.0 (cal / cm 3 ) 1 / 2 Above and 11.0 (cal / cm 3 ) 1 / 2Below, more preferably 8.5 (cal / cm 3 ) 1 / 2 Above and 10.0(cal / cm 3 ) 1 / 2 Below, more preferably 8.8 (cal / cm 3 ) 1 / 2 Above and 9.5 (cal / cm 3 ) 1 / 2 the following.

[0085] In addition, from the viewpoint of obtaining a fast development speed, the solubility parameter (SP value) of the polymer gel in the organic solvent-based developer is preferably 8.0 (cal / cm 3 ) 1 / 2 Above and 11.0 (cal / cm 3 ) 1 / 2 Below, more preferably 8.5 (cal / cm 3 ) 1 / 2 Above and 10.0(cal / cm 3 ) 1 / 2 Below, more preferably 8.8 (cal / cm 3 ) 1 / 2 Above and 9.5 (cal / cm 3 ) 1 / 2 the following.

[0086] From the viewpoint of obtaining a flexographic printing plate with excellent dimensional stability and ensuring a fast development speed, and further the dispersibility of the polymer gel in the organic solvent-based developer, the absolute value of the difference between the solubility parameter (SP value) of the organic solvent in the organic solvent-based developer used in the present embodiment and the solubility parameter (SP value) of the polymer gel is preferably 0.5 (cal / cm 3 ) 1 / 2 Above and 4.0(cal / cm 3 ) 1 / 2 Below, more preferably 0.6 (cal / cm 3 ) 1 / 2 Above and 3.0(cal / cm 3 ) 1 / 2 Below, more preferably 0.7 (cal / cm 3 ) 1 / 2 Above and 2.0(cal / cm 3 ) 1 / 2 the following.

[0087] The solubility parameters (SP values) of the organic solvent and the polymer gel in the organic solvent-based developer used in the method for producing a flexographic printing plate according to the present embodiment are defined as in the following formula (1).

[0088] SP value (δ) = (ΔE / V) 1 / 2 [(cal / cm 3 ) 1 / 2 ]···(1)

[0089] Here, V is the molar molecular volume of the solvent, and ΔE is the cohesive energy (evaporation energy).

[0090] The molar molecular volume and cohesive energy of the organic solvent can also be determined from known values, such as in the document "POLYMER ENGINEERING AND SCIENCE, Vol. 14, 147-154, 1974".

[0091] On the other hand, when the aforementioned parameters are not known parameters, actual measurement may be performed using a method called turbidity titration.

[0092] Specifically, first, to a solution obtained by dissolving a sample with an unknown SP value in a good solvent with a known SP value, a poor solvent with a lower SP value than the good solvent is gradually added dropwise, and the volume of the poor solvent at which the solute begins to precipitate is measured. Next, to a newly prepared solution obtained by dissolving a sample with an unknown SP value in a good solvent with a known SP value, a poor solvent with a higher SP value than the good solvent is gradually added dropwise, and the volume of the poor solvent at which the solute begins to precipitate is measured. By applying the volumes of various poor solvents obtained here to the following formula (2), the SP value (δ) can be obtained.

[0093] SP value (δ) = (V ml 1 / 2 ·δ ml +V mh 1 / 2 ·δ mh ) / (V ml 1 / 2 +V mh 1 / 2 )···(2)

[0094] Here, V ml is the volume of the poor solvent with low SP value, V mh is the volume of the poor solvent with high SP value, δ ml is the SP value of the poor solvent with a low SP value, δ mh It is the SP value of a poor solvent having a high SP value.

[0095] All SP values ​​described in the following Examples are values ​​actually measured by the above-mentioned turbidity point titration method.

[0096] The absolute value of the difference between the solubility parameter (SP value) of the organic solvent in the aforementioned organic solvent-based developer and the solubility parameter (SP value) of the aforementioned polymer gel can be controlled within the above-mentioned numerical range by selecting the organic solvent and the polymer gel in a manner of combining an organic solvent and a polymer gel having appropriate solubility parameters.

[0097] (Post-processing process)

[0098] After the development step, post-exposure is performed as necessary to obtain a flexographic printing plate.

[0099] As the post-exposure treatment, there is a method of irradiating the surface with light having a wavelength of 300 nm or less. If necessary, light having a longer wavelength than 300 nm may be used in combination.

[0100] (Flexographic printing plate)

[0101] In the method for producing a flexographic printing plate of the present embodiment, a flexographic printing original plate is used in which at least a support, a photosensitive resin composition layer, and an infrared ablative layer are sequentially laminated.

[0102] If necessary, functional layers such as an intermediate layer and an adhesive layer may be provided between these layers.

[0103] Hereinafter, the structure of the flexographic printing original plate used in this embodiment will be described.

[0104] <Support>

[0105] The support constituting the flexographic printing plate is not limited to the following supports, and examples thereof include polypropylene film, polyethylene film, polyester film such as polyethylene terephthalate and polyethylene naphthalate; and polyamide film.

[0106] Among these, the support is preferably a polyester film.

[0107] The thickness of the support is preferably 75 μm or more and 300 μm or less. From the viewpoint of the strength of the flexographic printing plate, it is preferably 75 μm or more, and from the viewpoint of flexibility, it is preferably 300 μm or less.

[0108] An adhesive layer may be provided between the support and the photosensitive resin composition layer described later for the purpose of improving the adhesive force therebetween.

[0109] The material of the adhesive layer is not limited to the following materials, and examples thereof include compositions containing adhesive polymers such as polyurethane, polyamide, and thermoplastic elastomer and containing adhesive active ingredients such as isocyanate compounds and ethylenically unsaturated compounds. In addition, various auxiliary additives such as plasticizers, thermal polymerization inhibitors, ultraviolet absorbers, anti-halation agents, light stabilizers, photopolymerization initiators, photopolymerizable monomers, dyes, etc. may be added to the adhesive layer.

[0110] Furthermore, in order to further improve the adhesive force between the adhesive layer and the support, at least one adhesive layer may be provided between the adhesive layer and the support.

[0111] <Photosensitive resin composition layer>

[0112] The flexographic printing plate used in the method for producing a flexographic printing plate according to the present embodiment has a photosensitive resin composition layer on a support.

[0113] The photosensitive resin composition layer constituting the flexographic printing plate preferably contains, for example, a thermoplastic elastomer (a-1), polymer particles (a-2), a photopolymerizable monomer (a-3), and a photopolymerization initiator (a-4).

[0114] Furthermore, the photosensitive resin composition layer may contain, in addition to the above-mentioned components, a liquid diene (a-5), an organosilicon compound (a-6), and the like as necessary.

[0115] The photosensitive resin composition layer may have a dispersed phase and a continuous phase. From the viewpoint of obtaining a fast development speed, the thermoplastic elastomer (a-1) and the polymer particles (a-2) are preferably phase-separated. Either the thermoplastic elastomer (a-1) or the polymer particles (a-2) may be a continuous phase or a dispersed phase, and more preferably the thermoplastic elastomer (a-1) is a continuous phase and the polymer particles (a-2) are a dispersed phase.

[0116] These components are described in detail below, and as these components, for example, components described in “Japanese Patent Application Laid-Open No. 2018-120131” can be used.

[0117] As a method for confirming that phase separation has occurred, for example, hardness information can be obtained using an atomic force microscope (AFM) and the hardness distribution can be measured.

[0118] [Thermoplastic elastomer (a-1)]

[0119] The thermoplastic elastomer (a-1) is not limited to the following, and examples thereof include thermoplastic elastomers having a structural unit derived from a conjugated diene and / or a vinyl aromatic compound.

[0120] The thermoplastic elastomer (a-1) may be a homopolymer or a copolymer. In the case of a copolymer, the thermoplastic elastomer (a-1) may be a random polymer or a block polymer.

[0121] Among these, the thermoplastic elastomer (a-1) is preferably a thermoplastic elastomer containing at least one polymer block mainly composed of conjugated diene monomer units and at least one polymer block mainly composed of vinyl aromatic monomer units.

[0122] In addition, in this specification, "mainly composed of" means that 60 mass % or more of the polymer block is composed of a predetermined monomer.

[0123] When the thermoplastic elastomer (a-1) has a polymer block mainly composed of conjugated diene monomer units, the content of the conjugated diene monomer units in the polymer block mainly composed of conjugated diene monomer units is preferably 80% by mass or more, more preferably 90% by mass or more.

[0124] The conjugated diene is not limited to the following substances, and examples thereof include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, chloroprene, etc. Among these, 1,3-butadiene is particularly preferred from the viewpoint of the wear resistance of the photosensitive resin composition layer.

[0125] These monomers may be used alone or in combination of two or more.

[0126] In the polymer block mainly composed of conjugated diene monomer units, from the viewpoint of flexographic printing plate formability, the vinyl bond content is preferably 5 mol% to 50 mol% relative to the total amount of the conjugated diene monomer units, more preferably 8 mol% to 50 mol%, and further preferably 10 mol% to 40 mol%. Here, the "vinyl bond content" refers to the 1,2-vinyl bond content and the 3,4-vinyl bond content.

[0127] From the viewpoint of printing durability of the flexographic printing plate, the number average molecular weight of the polymer block mainly composed of conjugated diene monomer units is preferably 20,000 to 250,000, more preferably 30,000 to 200,000, and further preferably 40,000 to 150,000.

[0128] The polymer block with conjugated diene monomer units as the main body may contain alkylene units. The method for introducing the alkylene units is not particularly limited, and examples thereof include: a method of using monoolefins such as ethylene and butene as raw material monomers for polymer blocks with conjugated dienes as the main body and polymerizing; a method of hydrogenating the conjugated diene polymer block, etc. In particular, from the perspective of ease of acquisition, a method of hydrogenating the polymer block with conjugated diene monomer units as the main body is preferred.

[0129] In the polymer block with conjugated diene monomer units as the main body, the content of the alkylene unit is preferably 5 mol% or more and 50 mol% or less relative to the total amount of monomer units constituting the polymer block with the conjugated diene monomer units as the main body, more preferably 10 mol% or more and 35 mol% or less, and further preferably 10 mol% or more and 25 mol% or less. By making the content of the alkylene unit 5 mol% or more, there is a tendency to further improve the solvent resistance of the flexographic printing plate. In addition, by making the content of the alkylene unit 50 mol% or less, there is a tendency to further improve the transparency of the photosensitive resin composition layer.

[0130] From the viewpoint of solvent resistance of the flexographic printing plate, the polymer block with conjugated diene monomer units as the main body preferably contains alkylene units, and more preferably contains 1,4-butadiene units, 1,2-butadiene (vinyl) units and butylene (alkylene) units at the same time. At this time, the polymer block with conjugated diene monomer units as the main body further preferably contains 1,4-butadiene units 25mol% or more and 70mol% or less, 1,2-butadiene (vinyl) units 0mol% or more and 50mol% or less, and butylene units 10mol% or more and 50mol% or less. This polymer block is obtained by hydrogenating the polymer block portion with butadiene as the main body.

[0131] It should be noted that the content and ratio of the conjugated diene monomer unit, the amount of vinyl bonds of the conjugated diene, and the content and ratio of the vinyl aromatic monomer unit in the polymer block mainly composed of the thermoplastic elastomer (a-1) and the conjugated diene monomer unit can be measured using a nuclear magnetic resonance apparatus ( 1 H-NMR) was used for determination.

[0132] The vinyl aromatic compound is not limited to the following compounds, and examples thereof include monomers such as styrene, tert-butylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene, vinylpyridine, p-methylstyrene, tert-butylstyrene, α-methylstyrene, and 1,1-diphenylethylene. In particular, styrene is preferred because it can smoothly mold a flexographic printing plate at a relatively low temperature (hereinafter also referred to as "high moldability").

[0133] These monomers may be used alone or in combination of two or more.

[0134] The number average molecular weight of the polymer block mainly composed of vinyl aromatic monomer units constituting the thermoplastic elastomer (a-1) is preferably 100,000 or less from the viewpoint of not causing the flexographic printing plate to exhibit orientation, and is preferably 3,000 or more from the viewpoint of defect resistance during platemaking and printing. The number average molecular weight of the polymer block mainly composed of vinyl aromatic monomer units is more preferably 5,000 or more and 80,000 or less, and further preferably 5,000 or more and 60,000 or less.

[0135] The content of the vinyl aromatic monomer unit in the thermoplastic elastomer (a-1) is preferably 13% by mass to 25% by mass, more preferably 15% by mass to 24% by mass, and further preferably 16% by mass to 23% by mass, based on the total amount of the block copolymer.

[0136] When the content of the vinyl aromatic monomer unit is 25% by mass or less, the photosensitive resin composition has high moldability, the convex portion of the flexographic printing plate has high scratch resistance, and the hardness of the printing plate when the ink component adheres tends to be maintained at a high level. On the other hand, when the content of the vinyl aromatic monomer unit is 13% by mass or more, the cold deformation resistance of the flexographic printing original plate tends to be further improved.

[0137] From the viewpoint of obtaining a fast development speed, the solubility parameter (SP value) of the thermoplastic elastomer (a-1) used in the photosensitive resin composition layer is preferably 8.0 (cal / cm 3 ) 1 / 2 Above and 11.0 (cal / cm 3 ) 1 / 2 Below, more preferably 8.5 (cal / cm 3 ) 1 / 2 Above and 10.0(cal / cm 3 ) 1 / 2 Below, more preferably 8.8 (cal / cm 3 )1 / 2 Above and 9.5 (cal / cm 3 ) 1 / 2 the following.

[0138] The solubility parameter (SP value) of the thermoplastic elastomer (a-1) can be measured by the method described in the above section [Solubility parameters of organic solvent and polymer gel in organic solvent-based developer].

[0139] In addition, from the viewpoint of obtaining a flexographic printing plate having excellent image reproducibility and high printing quality, the absolute value of the difference between the solubility parameter (SP value) of the thermoplastic elastomer (a-1) used in the photosensitive resin composition and the solubility parameter (SP value) of the polymer particles (a-2) is preferably 0.1 (cal / cm 3 ) 1 / 2 Above and 2(cal / cm 3 ) 1 / 2 Below, more preferably 0.2 (cal / cm 3 ) 1 / 2 Above and 1(cal / cm 3 ) 1 / 2 Below, more preferably 0.3 (cal / cm 3 ) 1 / 2 Above and 0.8(cal / cm 3 ) 1 / 2 the following.

[0140] The absolute value of the difference between the solubility parameter (SP value) of the aforementioned thermoplastic elastomer (a-1) and the solubility parameter (SP value) of the aforementioned polymer particles (a-2) can be controlled to the above-mentioned numerical range by selecting the thermoplastic elastomer and the polymer particles in such a manner that the thermoplastic elastomer and the polymer particles having appropriate solubility parameters are combined.

[0141] From the viewpoint of printing durability during printing, when the total amount of the photosensitive resin composition layer is set to 100 mass%, the content of the thermoplastic elastomer (a-1) in the photosensitive resin composition layer constituting the flexible printing original plate is preferably 15 mass% to 90 mass%, more preferably 15 mass% to 80 mass%, and further preferably 20 mass% to 75 mass%.

[0142] [Polymer particles (a-2)]

[0143] The photosensitive resin composition layer of the flexographic printing plate used in the method for producing a flexographic printing plate of the present embodiment preferably contains polymer particles (a-2).

[0144] The polymer particles (a-2) are polymer particles obtained by internal crosslinking of monomers. The polymer particles (a-2) are not limited to the following particles, and are obtained by preparing a compound containing a gel obtained by dispersing polymer particles as a dispersoid in water by, for example, emulsion polymerization, and removing water from the compound containing the obtained gel.

[0145] The polymer particles (a-2) may be the same as or different from the polymer gel contained in the organic solvent-based developer. If they are the same, the concentration of the polymer gel in the organic solvent-based developer is maintained at a fixed concentration, and the development quality is more stable, which is preferred.

[0146] Examples of the method for producing the polymer particles (a-2) include a method of synthesizing by various polymerization methods such as suspension polymerization and emulsion polymerization, and a method of producing by mechanochemistry.

[0147] The polymer constituting the polymer particles (a-2) is not limited to the following polymers, and examples thereof include polymers having a butadiene skeleton, such as polybutadiene, acrylonitrile-butadiene copolymers, styrene-butadiene copolymers, and (meth)acrylate-butadiene copolymers; polymers having an isoprene skeleton, such as polyisoprene and polychloroprene; polymers obtained by further polymerizing a monomer having a carboxyl group and / or a hydroxyl group to the polymer having a butadiene skeleton or an isoprene skeleton; polymers obtained by further polymerizing a (meth)acrylate to the polymer having a butadiene skeleton or an isoprene skeleton; polymers obtained by further polymerizing a (meth)acrylate and a monomer having a carboxyl group and / or a hydroxyl group to the polymer having a butadiene skeleton or an isoprene skeleton; polyurethane, vinyl pyridine polymers, butyl polymers, polysulfide rubber polymers, acrylate polymers, and natural rubber.

[0148] The number average particle size of the polymer particles (a-2) contained in the photosensitive resin composition layer is preferably 500 nm or less, more preferably 100 nm or less. When the number average particle size is 500 nm or less, the developability of the flexographic printing original plate tends to be further improved.

[0149] The toluene gel fraction of the polymer particles (a-2) is preferably 50% or more and 100% or less, more preferably 60% or more and 100% or less, and even more preferably 85% or more and 100% or less.

[0150] When the toluene gel fraction is 50% or more, the flexographic printing plate tends to have sufficient strength for practical use. When the toluene gel fraction is 100% or less, the miscibility of the polymer particles (a-2) and the thermoplastic elastomer (a-1) tends to be good.

[0151] Here, the toluene gel fraction is determined as follows.

[0152] An appropriate amount of a dispersion of about 30% by mass of polymer particles (a-2) was dropped onto a Teflon (registered trademark) sheet and dried at 130°C for 30 minutes to obtain 0.5 g of polymer particles (a-2). The particles were immersed in 30 mL of toluene at 25°C and shaken for 3 hours using an oscillator. Thereafter, the particles were filtered using a 320SUS mesh, and the non-passing components were dried at 130°C for 1 hour. The mass fraction (%) obtained by dividing the mass of the dried component by 0.5 (g) was taken as the toluene gel fraction.

[0153] The toluene gel fraction of the polymer particles (a-2) can be controlled by a known method, for example, by adjusting the amount of the chain transfer agent used when synthesizing the polymer particles (a-2), thereby being controlled within the above numerical range.

[0154] From the viewpoint of dispersibility in the photosensitive resin layer, the solubility parameter of the polymer particles (a-2) used in the photosensitive resin composition layer is preferably 8.0 (cal / cm 3 ) 1 / 2 Above and 11.0 (cal / cm 3 ) 1 / 2 Below, more preferably 8.5 (cal / cm 3 ) 1 / 2 Above and 10.0(cal / cm 3 ) 1 / 2 Below, more preferably 8.8 (cal / cm 3 ) 1 / 2 Above and 9.5 (cal / cm 3 ) 1 / 2 the following.

[0155] The solubility parameter (SP value) of the polymer particles (a-2) can be measured by the method described in the above section [Solubility parameters of organic solvent and polymer gel in organic solvent-based developer].

[0156] From the viewpoint of developability when making a flexographic printing plate, when the total amount of the photosensitive resin composition is set to 100 mass%, the content of the polymer particles (a-2) in the photosensitive resin composition layer constituting the flexographic printing original plate is preferably 10 mass% or more and 70 mass% or less, more preferably 15 mass% or more and 60 mass% or less, and further preferably 20 mass% or more and 50 mass% or less.

[0157] [Photopolymerizable monomer (a-3)]

[0158] The photopolymerizable monomer (a-3) is not limited to the following monomers, and examples thereof include esters of acrylic acid, methacrylic acid, fumaric acid, maleic acid, etc.; derivatives of acrylamide and methacrylamide; allyl esters, styrene and its derivatives; and N-substituted maleimide compounds.

[0159] Specifically, the photopolymerizable monomer (a-3) is not limited to the following monomers, and examples thereof include diacrylates and dimethacrylates of alkane diols such as 1,6-hexanediol and 1,9-nonanediol; or diacrylates and dimethacrylates of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, butanediol, and dicyclopentadienyl; trimethylolpropane tri(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, isobornyl (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, pentaerythritol tetrakis Alcohol tetra(meth)acrylate, N,N'-hexamethylenebisacrylamide and methacrylamide, styrene, vinyltoluene, divinylbenzene, phthalic acid diacrylate, triallyl cyanurate, diethyl fumarate, dibutyl fumarate, dioctyl fumarate, distearyl fumarate, butyloctyl fumarate, diphenyl fumarate, dibenzyl fumarate, dibutyl maleate, dioctyl maleate, bis(3-phenylpropyl) fumarate, dilauryl fumarate, dibehenyl fumarate, N-laurylmaleimide, etc.

[0160] These may be used alone or in combination of two or more.

[0161] From the viewpoint of high scratch resistance of the convex portion of the flexographic printing plate, the photopolymerizable monomer (a-3) is preferably a di(meth)acrylate monomer having two (meth)acrylate groups in one molecule. The content of such a di(meth)acrylate monomer is preferably 2.0% by mass or more, more preferably 2.0 to 20% by mass, and further preferably 5.0 to 16% by mass relative to the total amount of the photosensitive resin composition.

[0162] From the viewpoint of obtaining clear printing, when the total amount of the photosensitive resin composition is set to 100 mass %, the content of the photopolymerizable monomer (a-3) in the photosensitive resin composition layer constituting the flexographic printing original plate is preferably 1 to 25 mass %, more preferably 5 to 20 mass %, and further preferably 8 to 15 mass %.

[0163] [Photopolymerization initiator (a-4)]

[0164] The photopolymerization initiator (a-4) is a compound that generates radicals by absorbing light energy, and various known compounds can be used. Various organic carbonyl compounds are suitable, and aromatic carbonyl compounds are particularly suitable.

[0165] The photopolymerization initiator (a-4) is not limited to the following substances, and examples thereof include thioxanthones such as benzophenone, 4,4-bis(diethylamino)benzophenone, tert-butyl anthraquinone, 2-ethyl anthraquinone, 2,4-diethyl thioxanthone, isopropyl thioxanthone, and 2,4-dichlorothioxanthone; diethoxyacetophenone, 2,2-dimethoxyphenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, benzyl dimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholinyl (4-thiomethylphenyl) propane-1-one, 2 -Benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone and other acetophenones; benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether and other benzoin ethers; acyl phosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; methyl benzoylformate; 1,7-bisacridinylheptane; 9-phenylacridine; 2,6-di-tert-butyl-p-cresol, etc.

[0166] These may be used alone or in combination of two or more.

[0167] From the viewpoint of improving the plate-forming properties when producing a flexographic printing plate and obtaining clear printing, that is, excellent printing reproducibility in a region where the dot area is about 0 to 10%, the content of the photopolymerization initiator (a-4) in the photosensitive resin composition layer constituting the flexographic printing original plate is preferably 0.1 to 10.0% by mass, more preferably 1.0 to 8.0% by mass, and even more preferably 1.5 to 5.0% by mass, when the total amount of the photosensitive resin composition is set to 100% by mass.

[0168] In addition, as the photopolymerization initiator (a-4), a disintegration type photopolymerization initiator and a hydrogen abstraction type photopolymerization initiator may be used in combination. From the viewpoint of improving the image reproducibility and abrasion resistance of the flexographic printing plate, the content of the hydrogen abstraction type photopolymerization initiator in the photosensitive resin composition is preferably 1.0% by mass or less, more preferably 0.5% by mass or less.

[0169] [Liquid Diene (a-5)]

[0170] The photosensitive resin composition layer may contain a liquid diene (a-5).

[0171] The liquid diene (a-5) refers to a liquid compound having a carbon-carbon double bond.

[0172] Here, in this specification, the "liquid" of "liquid diene" means: a property that it is easy to flow and deform and can solidify into a deformed shape by cooling. This term corresponds to an elastomer that has the property of instantly deforming according to the external force when an external force is applied and recovering to the original shape in a short time when the external force is removed.

[0173] The liquid diene (a-5) is not limited to the following substances, and examples thereof include liquid polybutadiene, liquid polyisoprene, modified liquid polybutadiene, modified liquid polyisoprene, liquid acrylonitrile-butadiene copolymer, and liquid styrene-butadiene copolymer. The liquid diene is a copolymer containing 50% by mass or more of a diene component.

[0174] Among them, from the viewpoint of the mechanical properties of the flexographic printing original plate and the flexographic printing plate obtained using the same, the liquid diene (a-5) is preferably a liquid polybutadiene.

[0175] The number average molecular weight of the liquid diene (a-5) is not particularly limited as long as it is liquid at 20°C, but is preferably 500 to 60,000, more preferably 500 to 50,000, and even more preferably 800 to 50,000, from the viewpoint of the printing durability and handling properties of the flexographic printing plate obtained using the flexographic printing original.

[0176] From the viewpoint of the printing durability of the flexographic printing plate and the flexographic printing plate obtained using the same, when the total amount of the photosensitive resin composition layer is set to 100% by mass, the content of the liquid diene (a-5) in the photosensitive resin composition layer constituting the flexographic printing plate is preferably 10 to 40% by mass, more preferably 15 to 40% by mass, and further preferably 20 to 40% by mass.

[0177] [Organosilicon compound (a-6)]

[0178] Examples of the organosilicon compound (a-6) include silicone oil, silane coupling agent, silane compound, silicone rubber, silicone resin, etc. In particular, silicone oil is preferred because the component can be easily transferred to the surface and the effect of reducing the surface energy is high.

[0179] As the organosilicon compound (a-6), it is not limited to the following compounds, and compounds having polyalkylsiloxane in the main chain, such as polydimethylsiloxane and polydiethylsiloxane, can be listed. In addition, the organosilicon compound (a-6) can be a compound having a polysiloxane structure in a part of the molecule. Furthermore, the organosilicon compound (a-6) can be a compound having a specific organic group introduced into the polysiloxane structure. Specifically, a compound having an organic group introduced into the side chain of polysiloxane, a compound having an organic group introduced into both ends of polysiloxane, a compound having an organic group introduced into a single end of polysiloxane, a compound having an organic group introduced into both the side chain and the end of polysiloxane, etc. can be used.

[0180] As the organic group introduced into the polysiloxane structure, it is not limited to the following organic groups, and examples thereof include amino, carboxyl, methanol, aryl, alkyl, alkoxycarbonyl, alkoxy, linear or branched alkyl substituted with at least one aryl, polyoxyalkylene (hereinafter also referred to as polyether group), etc. Among these, as the organosilicon compound (a-6), it is more preferred to use polysiloxane as the main skeleton and silicone oil having one or more groups selected from the group consisting of amino, polyether, and methanol at at least one end. By using such an organosilicon compound (a-6), there is a tendency that the transparency of the photosensitive resin composition layer is further improved. It should be noted that, as a commercial product of such an organosilicon compound (a-6), it is not particularly limited, and examples thereof include KF-6000 manufactured by Shin-Etsu Chemical Co., Ltd.

[0181] The content of the organosilicon compound (a-6) in the photosensitive resin composition layer constituting the flexographic printing plate is preferably 0.1% by mass to 5.0% by mass, more preferably 0.5% by mass to 3.0% by mass, and even more preferably 0.5% by mass to 2.0% by mass, relative to the total amount of the photosensitive resin composition layer.

[0182] <Infrared Ablation Layer>

[0183] The flexographic printing plate used in the method for producing a flexographic printing plate according to the present embodiment has an infrared ablative layer on the photosensitive resin composition layer.

[0184] The infrared ablation layer can be processed by infrared rays, and plays a role of a mask image when the photosensitive resin composition layer is exposed and cured. When the unexposed part of the photosensitive resin composition layer is washed after the exposure, the infrared ablation layer is also removed simultaneously.

[0185] The infrared ablation layer preferably contains a binder polymer and an infrared sensitive substance.

[0186] The binder polymer is not limited to the following substances, and examples thereof include polyamide, polyester, and copolymers formed by monovinyl-substituted aromatic hydrocarbons and conjugated dienes. Copolymers formed by monovinyl-substituted aromatic hydrocarbons such as styrene, α-methylstyrene, and vinyltoluene and conjugated dienes such as 1,3-butadiene and isoprene are particularly preferred. By using such a binder polymer to form the infrared ablation layer, the affinity with the above-mentioned photosensitive resin composition layer and the intermediate layer provided as required is high, and the adhesion becomes good.

[0187] When polyester is used as the binder polymer, the number average molecular weight of the polyester is preferably 300 or more and 10,000 or less.

[0188] Furthermore, the polyester is not particularly limited, and for example, polyesters synthesized from alkanediol and adipic acid, polyesters synthesized from alkanediol and phthalic acid, polycaprolactone, and polyesters obtained by combining two or more of these polyesters can be preferably used.

[0189] Furthermore, the polyester may contain various functional groups such as an amino group, a nitro group, a sulfonic acid group, and a halogen group within a range that does not impair the compatibility with other binder polymers, infrared sensitive substances, and non-infrared radiation shielding substances.

[0190] The infrared sensitive substance is not particularly limited, and for example, a monomer or compound having strong absorption in the range of 750 to 2000 nm can be preferably used.

[0191] Examples of the infrared sensitive substance include, but are not limited to, inorganic pigments such as carbon black, graphite, copper chromite, and chromium oxide; and pigments such as polyphthalocyanine compounds, cyanine pigments, and metal thiolate pigments.

[0192] The content of these infrared sensitive substances in the infrared ablation layer is preferably within a range that provides sensitivity that enables ablation by the laser beam used. The content of the infrared sensitive substances is preferably 10% by mass or more and 80% by mass or less relative to the total amount of the infrared ablation layer.

[0193] In addition, the infrared sensitive material can use a material that reflects or absorbs radiation such as ultraviolet rays. Such a material includes radiation absorbers such as ultraviolet rays, carbon black, graphite, etc., and the amount of the infrared ablation layer is preferably set in a manner that can achieve a desired optical density. Generally speaking, the infrared ablation layer is preferably added in a manner that the optical density becomes 2 or more, preferably 3 or more.

[0194] <Middle Layer>

[0195] The flexographic printing plate used in the method for producing a flexographic printing plate of the present embodiment may have an intermediate layer having a predetermined function between the photosensitive resin composition layer and the infrared ablation layer described later.

[0196] In order to produce a high-definition printed material with a highlight area, it is necessary to form a tiny dot with a flat portion of the front end of the dot having a diameter of 10 to 20 μm and a relief depth of 100 μm or more in the flexographic printing plate. In order to realize such a tiny dot, the intermediate layer is preferably an oxygen barrier layer with oxygen barrier capability. In addition, the intermediate layer can be an adhesive layer with an adhesive function.

[0197] When the photosensitive resin composition layer is cured by ultraviolet irradiation, the curing is carried out by free radical polymerization. If oxygen coexists during polymerization, the free radical generating compound reacts with oxygen to inhibit the polymerization reaction. If the polymerization reaction is inhibited and an unreacted portion remains in the photosensitive resin composition layer, the final pattern formed presents a shape having a curved portion at the front end. In contrast, if the coexisting amount of oxygen is reduced during ultraviolet curing, the polymerization reaction is not easily inhibited, and the final pattern formed presents a shape having a flat portion at the front end. Therefore, when it is desired to make a pattern having a flat portion at the front end in a flexible printing plate, it is effective to make the intermediate layer a layer having oxygen barrier capability to reduce the oxygen in contact with the photosensitive resin composition layer.

[0198] In addition, the intermediate layer also has the function of protecting the infrared ablation layer.

[0199] In the conventional manufacturing process of flexographic printing plates, the infrared ablation layer may come into contact with rollers when the film is conveyed, or the film roll may be wound up during transportation, which may cause friction with the prescribed film protecting the infrared ablation layer, resulting in physical defects and pinholes.

[0200] In addition, when the photosensitive resin composition layer and the infrared ablation layer are laminated by a method in which the photosensitive resin composition layer is extruded and coated on the infrared ablation layer, pinholes may be generated in the infrared ablation layer due to friction generated when the heated and molten photosensitive resin composition flows on the infrared ablation layer.

[0201] In order to prevent the generation of pinholes in the infrared ablation layer, the intermediate layer constituting the flexographic printing original plate preferably has physical strength and heat resistance.

[0202] As described above, in order to produce a high-definition printed material with a highlight area, it is necessary to form a tiny dot with a diameter of 10 to 20 μm on the flat portion of the front end of the dot of the flexible printing plate. Therefore, when the infrared ablation layer has a pinhole of more than 20 μm and the mask image used to form the tiny dots around it overlaps, poor dot formation may occur, and a high-definition flexible printing plate with a highlight area cannot be produced.

[0203] From this viewpoint, as described above, the intermediate layer is preferably an oxygen barrier layer having oxygen barrier capability, and preferably has physical strength and heat resistance.

[0204] Furthermore, from the viewpoint of simplicity of the production process of the flexographic printing plate, the intermediate layer is preferably capable of being cleaned with the same cleaning solution as that of the infrared ablative layer and the photosensitive resin composition layer.

[0205] When the intermediate layer has high cleaning properties, the time required for the cleaning step can be shortened, workability is improved, and the photosensitive resin composition layer located below the intermediate layer can be easily developed.

[0206] Materials that can be suitably used for the intermediate layer are not limited to the following materials, and examples thereof include polymers such as ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl pyrrolidone, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyacetal, polycarbonate, polystyrene, polycarbonate, polyethylene, polypropylene, cellulose derivatives, polyester, polyamide, polyimide, polyurethane, silicone rubber, butyl rubber and isoprene rubber.

[0207] In addition, the intermediate layer preferably contains a water-dispersible latex.

[0208] The water-dispersible latex is not limited to the following latexes, and examples thereof include water-dispersible latex polymers such as polybutadiene latex, natural rubber latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, polyvinylidene chloride latex, polychloroprene latex, polyisoprene latex, polyurethane latex, methyl methacrylate-butadiene copolymer latex, vinylpyridine polymer latex, butyl polymer latex, polysulfide rubber polymer latex, and acrylate polymer latex; and polymers obtained by copolymerizing these polymers with other components such as acrylic acid and methacrylic acid.

[0209] These polymers may be used alone or in combination of two or more.

[0210] In addition, other components such as surfactants, anti-blocking agents, mold release agents, UV absorbers, dyes, pigments, etc. may be added to the intermediate layer.

[0211] The thickness of the intermediate layer is preferably 0.5 μm or more and 20 μm or less. By being 0.5 μm or more, sufficient film strength can be obtained, and by being 20 μm or less, sufficient cleaning properties can be obtained. The thickness of the intermediate layer is more preferably 0.5 μm or more and 10 μm or less, and further preferably 0.5 μm or more and 5 μm or less.

[0212] [Flexographic printing plate, printing method]

[0213] The flexographic printing plate obtained by the method for producing a flexographic printing plate according to the present embodiment includes a support and a cured photosensitive resin composition layer having an arbitrary concavo-convex pattern formed thereon by relief exposure.

[0214] Flexographic printing is performed by allowing ink to adhere to the top of the photosensitive resin composition layer during printing, and the adhered ink adheres to the printed object.

[0215] The printing method of the present embodiment comprises the steps of obtaining a flexographic printing plate by the method for producing a flexographic printing plate of the present embodiment described above, and performing printing using the flexographic printing plate.

[0216] Example

[0217] Hereinafter, the present embodiment will be described in more detail with reference to specific examples and comparative examples, but the present invention is not limited to the following examples and comparative examples.

[0218] [Examples 1 to 16] [Comparative Examples 1 to 5]

[0219] The methods for producing the flexographic printing plates of Examples 1 to 16 and Comparative Examples 1 to 5 are described below.

[0220] ((1) Production of polymer gel / polymer particles)

[0221] A polymer gel to be blended into an organic solvent-based developer used in a process for producing a flexographic printing plate and polymer particles to be blended into a photosensitive resin composition layer were prepared as follows.

[0222] It should be noted that the "polymer gel" and "polymer particles" in the following polymer gel / polymer particles A to E respectively refer to the polymer gel contained in the organic solvent-based developer and the polymer particles contained in the photosensitive resin composition layer, and the materials thereof are the same.

[0223] <Production of Polymer Gel / Polymer Particles A>

[0224] Into a pressure-resistant reaction vessel equipped with a stirring device and a temperature-regulating jacket, 125 parts by mass of water and 2 parts by mass of ammonium salt of α-sulfo(1-nonylphenoxy)methyl-2-(2-propenyloxy)ethoxy-poly(oxy-1,2-ethanediyl) "ADEKA REASOAP" (manufactured by ADEKA Corporation) as a reactive emulsifier were initially charged, and the internal temperature was raised to 80° C., and a monomer mixture containing 10 parts by mass of styrene, 60 parts by mass of butadiene, 23 parts by mass of butyl acrylate, 5 parts by mass of methacrylic acid and 2 parts by mass of acrylic acid, an oily mixed liquid containing 2 parts by mass of tert-dodecyl mercaptan, 28 parts by mass of water, 1.2 parts by mass of sodium persulfate, 0.2 parts by mass of sodium hydroxide and 2 parts by mass of an aqueous solution of ammonium salt of α-sulfo(1-nonylphenoxy)methyl-2-(2-propenyloxy)ethoxy-poly(oxy-1,2-ethanediyl) were added at a predetermined flow rate over 5 hours and 6 hours, respectively.

[0225] Next, the temperature was maintained at 80° C. for 1 hour to terminate the polymerization reaction, and after obtaining a copolymer latex, the mixture was cooled.

[0226] Furthermore, the pH of the generated copolymer latex was adjusted to 7 with sodium hydroxide, unreacted monomers were removed by air stripping, and the mixture was filtered through a 200-mesh metal mesh to finally adjust the solid content concentration of the filtrate to 40% by mass, thereby obtaining an aqueous dispersion of a polymer gel.

[0227] The obtained aqueous dispersion of the polymer gel was dried in a vacuum dryer at 50° C. to remove water, thereby obtaining polymer gel / polymer particles A.

[0228] The polymer particles of the polymer gel / polymer particles A had a number average particle size of 66 nm and a toluene gel fraction of 99%.

[0229] The number average particle size of the polymer gel / polymer particles was measured in a state where the particles were dispersed in a developer using a dynamic light scattering particle size distribution measuring apparatus Microtrac (manufactured by Nikkiso Co., Ltd.).

[0230] In addition, the solubility parameter (SP value) of the polymer gel / polymer particles was determined using a turbidity point titration method.

[0231] Specifically, after dispersing it in a good solvent (hexane), a poor solvent (ethanol) is gradually added dropwise until separation or precipitation occurs, and the SP value (δ) is determined by applying the volume of the poor solvent added dropwise to the following formula (2).

[0232] SP value (δ) = (V ml 1 / 2 ·δ ml +V mh1 / 2 ·δ mh ) / (V ml 1 / 2 +V mh 1 / 2 )···(2)

[0233] (In the above formula (2), V ml is the volume of the poor solvent with low SP value, V mh is the volume of the poor solvent with high SP value, δ ml is the SP value of the poor solvent with a low SP value, δ mh It is the SP value of the poor solvent with a high SP value. )

[0234] The calculation was performed using the following good solvent and poor solvent and their respective SP values. The SP value was calculated similarly below.

[0235] Good solvent:

[0236] Toluene (SP value: 8.9 [(cal / cm 3 ) 1 / 2 ])

[0237] p-Xylene (SP value: 8.7 [(cal / cm 3 ) 1 / 2 ])

[0238] Butyl acetate (SP value: 8.5 [(cal / cm 3 ) 1 / 2 ])

[0239] Ethyl acetate (SP value: 9.1 [(cal / cm 3 ) 1 / 2 ])

[0240] Acetone (SP value: 9.8 [(cal / cm 3 ) 1 / 2 ])

[0241] Poor solvents:

[0242] n-Hexane (SP value: 7.2 [(cal / cm 3 ) 1 / 2 ])

[0243] Ethanol (SP value: 12.9 [(cal / cm 3 ) 1 / 2 ])

[0244] Water (SP value: 23.4 [(cal / cm 3 ) 1 / 2 ])

[0245] <Production of Polymer Gel / Polymer Particles B>

[0246] Polymer gel / polymer particles B were obtained in the same manner as in the above-mentioned polymer gel / polymer particles A except that the polymerization reaction temperature was set to 95°C.

[0247] The number average particle size of the high molecular gel / polymer particles B was 40 nm, and the toluene gel fraction was 98%.

[0248] The SP value was measured in the same manner as in the above-mentioned polymer gel / polymer particles A.

[0249] <Production of Polymer Gel / Polymer Particles C>

[0250] Polymer gel / polymer particles C were obtained in the same manner as in the above-mentioned polymer gel / polymer particles A except that the polymerization reaction temperature was set to 90°C.

[0251] The number average particle size of the high molecular gel / polymer particles C was 58 nm, and the toluene gel fraction was 99%.

[0252] The SP value was measured in the same manner as in the above-mentioned polymer gel / polymer particles A.

[0253] <Production of Polymer Gel / Polymer Particles D>

[0254] The polymerization reaction temperature was set to 70°C, and the amount of the ammonium salt of α-sulfo(1-nonylphenoxy)methyl-2-(2-propyleneoxy)ethoxy-poly(oxy-1,2-ethanediyl) "ADEKA REASOAP" (manufactured by ADEKA Corporation) added was set to 1.8 parts by mass. The same operation as the above-mentioned polymer gel / polymer particles A was performed to obtain polymer gel / polymer particles D.

[0255] The number average particle size of the high molecular gel / polymer particles D was 318 nm, and the toluene gel fraction was 95%.

[0256] The SP value was measured in the same manner as in the above-mentioned polymer gel / polymer particles A.

[0257] <Production of Polymer Gel / Polymer Particles E>

[0258] The polymerization reaction temperature was set to 65°C, and the amount of the ammonium salt of α-sulfo(1-nonylphenoxy)methyl-2-(2-propyleneoxy)ethoxy-poly(oxy-1,2-ethanediyl) "ADEKA REASOAP" (manufactured by ADEKA Corporation) added was set to 1.6 parts by mass. The same operation as the above-mentioned polymer gel / polymer particles A was performed to obtain polymer gel / polymer particles E.

[0259] The number average particle size of the high molecular gel / polymer particles E was 405 nm, and the toluene gel fraction was 97%.

[0260] The SP value was measured in the same manner as in the above-mentioned polymer gel / polymer particles A.

[0261] ((2) Preparation of base film (support) having adhesive layer)

[0262] As a solution for an adhesive layer to be applied on a base film (support), 55 parts by mass of TUFPRENE 912 (trade name, manufactured by Asahi Kasei Corporation), a block copolymer of styrene and 1,3-butadiene, 38 parts by mass of paraffin oil (average number of carbon atoms: 33, average molecular weight: 470, density at 15° C.: 0.868), 2.5 parts by mass of 1,9-nonanediol diacrylate, 1.5 parts by mass of 2,2-dimethoxy-phenylacetophenone, 3 parts by mass of EPOXY ESTER 3000M (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), and 1.5 parts by mass of VALIFAST YELLOW 3150 (trade name, manufactured by ORIENT CHEMICAL INDUSTRIES, Inc.) were dissolved in toluene to obtain a solution having a solid content of 25%.

[0263] Thereafter, the solution was applied to one side of a 100 μm thick polyester film using a knife coater so that the ultraviolet transmittance became 10%, and dried at 80° C. for 1 minute to obtain a base film (support) having an adhesive layer.

[0264] The ultraviolet transmittance of the support was calculated by measuring the transmission intensity with a UV illuminometer MO-2 (manufactured by ORC MANUFACTURING CO., LTD., trade name, UV-35 filter) using an ultraviolet exposure machine AFP-1500 (manufactured by Asahi Kasei Corporation).

[0265] ((3) Fabrication of a thin film having an infrared ablation layer)

[0266] 65% by mass of ASAFLEX 810 (trade name, manufactured by Asahi Kasei Corporation), a block copolymer of styrene and 1,3-butadiene, and 35% by mass of carbon black as an infrared sensitive substance were kneaded and cut into pellets using a kneader. Then, 90 parts by mass of the pellets and 10 parts by mass of 1,6-hexanediol adipate were dissolved in a mixed solvent prepared in a mass ratio of ethyl acetate / butyl acetate / propylene glycol monomethyl ether acetate = 50 / 30 / 20 using ultrasonic waves to prepare a uniform solution having a solid content of 12% by mass.

[0267] Next, the solution was applied using a knife coater in an amount of 4 to 5 g / m2 after drying. 2The film was coated on a polyester film forming a cover sheet with a thickness of 100 μm and dried at 80° C. for 1 minute to obtain a film having an ultraviolet shielding layer (infrared ablation layer) that can be cut by infrared rays.

[0268] The optical density of the thin film having the infrared ablation layer was measured by DM-500 (product name, manufactured by SCREEN Holdings Corporation) and the result was 3 to 4.

[0269] ((4) Production of flexographic printing plate)

[0270] <Production of Flexographic Printing Plate 1>

[0271] Using a pressure kneader, 32 parts by mass of the polymer gel / polymer particles A obtained in (1) above (used as polymer particles A) and 28 parts by mass of a styrene-butadiene-styrene copolymer having a styrene ratio of 24% [D-KX405: manufactured by Kraton Corporation] were mixed at 140°C.

[0272] Thereafter, a liquid mixture of 32 parts by mass of liquid polybutadiene [LBR-352: manufactured by Kuraray Co., Ltd.], 8 parts by mass of 1,9-nonanediol diacrylate, 5 parts by mass of 1,6-hexanediol dimethacrylate, 2 parts by mass of 2,2-dimethoxyphenylacetophenone, 1 part by mass of 2,6-di-tert-butyl-p-cresol, and 1 part by mass of carbinol-modified silicone oil [KF-6000: manufactured by Shin-Etsu Chemical Co., Ltd.] was added little by little over 15 minutes, and mixed for further 20 minutes to obtain a photosensitive resin composition.

[0273] Next, the film is placed in an extruder, and the surface of the base film (support) obtained in the above (2) on which the adhesive layer is formed is attached to one surface of the photosensitive resin composition layer extruded from the T-die. Furthermore, a release film (DIAFOIL MRV100 manufactured by Mitsubishi Chemical Corporation) is attached to the surface of the photosensitive resin composition layer opposite to the support laminated side, thereby obtaining a laminate of the support and the photosensitive resin composition layer.

[0274] Next, the release film is peeled off, and the cover film having the infrared ablative layer obtained in (3) is laminated so that the infrared ablative layer contacts the photosensitive resin composition layer, thereby obtaining a flexographic printing plate.

[0275] <Production of Flexographic Printing Master Plates 2 to 7>

[0276] Flexographic printing plates 2 to 7 were obtained in the same manner as in flexographic printing plate 1 except that the types of polymer particles and thermoplastic elastomer in the photosensitive resin composition layer were changed as shown in Tables 1 to 3. Tables 1 to 3 show materials used to prepare flexographic printing plates.

[0277] In addition, the symbols of the thermoplastic elastomers in the table are as follows.

[0278] [Thermoplastic elastomer used]

[0279] KX405: D-KX405, manufactured by Kraton Corporation (SP value: 9.0)

[0280] TUFPRENE 315: (manufactured by Asahi Kasei Corporation, trade name, styrene ratio: 20 mass %) (SP value: 9.1)

[0281] ASAPRENE 420P: (manufactured by Asahi Kasei Corporation, trade name) (SP value: 9.3)

[0282] <Production of Flexographic Printing Plate 8>

[0283] After 60 parts by mass of a styrene-butadiene-styrene copolymer "ASAPRENE 420P" (trade name, manufactured by Asahi Kasei Corporation) having a styrene ratio of 30% by mass was mixed at 140° C. using a pressure kneader, 32 parts by mass of a liquid polybutadiene [LBR-352: manufactured by Kuraray Co., Ltd.], 8 parts by mass of 1,9-nonanediol diacrylate, 5 parts by mass of 1,6-hexanediol dimethacrylate, 2 parts by mass of 2,2-dimethoxyphenyl acetophenone, 1 part by mass of 2,6-di-tert-butyl-p-cresol, and 1 part by mass of a liquid mixture of carbinol-modified silicone oil [KF-6000: manufactured by Shin-Etsu Chemical Co., Ltd.] were gradually added over 15 minutes, and kneading was further performed for 20 minutes to obtain a photosensitive resin composition.

[0284] The subsequent steps were carried out in the same manner as for the flexographic printing original plate 1, and a flexographic printing original plate 8 was obtained.

[0285] Tables 1 to 3 below show materials used for producing flexographic printing plates.

[0286] (Pattern exposure)

[0287] The cover sheet of the infrared ablation layer was peeled off, and a concave line with a width of 100 μm was drawn on the infrared ablation layer using a laser drawing machine (CDI) manufactured by ESKO, and then the infrared ablation layer side was exposed to 8000 mJ in an air atmosphere using the above-mentioned exposure machine.

[0288] Next, the flexographic printing original plate was exposed using an LED exposure machine (XPS) manufactured by ESKO Corporation so that the pattern height (RD) after curing would be approximately 0.6 mm.

[0289] (Development of Flexographic Printing Master Plate)

[0290] Next, development was performed by the method described below.

[0291] In Examples and Comparative Examples, as shown in Tables 1 to 3 below, a predetermined flexographic printing original plate was developed using a predetermined developer.

[0292] When the developer contained a polymer gel, the developer was prepared by adding the predetermined polymer gel / polymer particles (used as a polymer gel) shown in Tables 1 to 3 to the contents shown in Tables 1 to 3.

[0293] When the developer does not contain the polymer gel, it is indicated as "none" in the table.

[0294] The film was fixed by sticking a double-sided tape on a rotating drum of an "AFP-1500" developer (trade name, manufactured by Asahi Kasei Corporation), developed at a liquid temperature of 25° C., and dried at 60° C. for 90 minutes.

[0295] <Type of developer>

[0296] "Cylosol" (manufactured by DUPONT SPECIALTY PRODUCTS, trade name) (SP value: 9.4)

[0297] "SOLVIT" (manufactured by MacDermid Co., Ltd., Japan, trade name) (SP value: 10.0)

[0298] 3-Methoxybutyl acetate (SP value: 9.1)

[0299] 1-Propanol (SP value: 12.8)

[0300] Pure water

[0301] <Types of polymer gel or particles contained in the developer>

[0302] Polymer gels A to E prepared as above

[0303] MEK-AC-5140Z: (silicon dioxide, number average particle size: 85 nm, manufactured by Nissan Chemical Co., Ltd.)

[0304] FINE-SPHERE FS102: (styrene-acrylic particles, toluene gel fraction 0%, number average particle size 80 nm, manufactured by Nippon Paint Co., Ltd.)

[0305] In addition, the number average particle size of FINE-SPHERE FS102 is the particle size before being put into the developer.

[0306] (Post-process)

[0307] In order to make the surface sticky, the entire surface of the dried flexographic printing plate was irradiated with a germicidal lamp (GL-30, trade name, manufactured by Toshiba Lighting & Technology Co., Ltd.) with a central wavelength of 254 nm using AFP-1216LF (manufactured by Asahi Kasei Corporation) at 2000 mJ / cm 2 exposure to obtain a flexible printing plate.

[0308] The post-exposure based on the germicidal lamp is calculated here based on the illuminance measured using the UV-25 filter of the "UV-MO2" machine.

[0309] 〔Measurement and calculation methods of various physical property values〕

[0310] (Absolute value of the difference between the SP value of the developer solvent and the SP value of the polymer gel)

[0311] The calculation is performed based on the SP value of the solvent described in the above-mentioned <Type of developer> and the SP value of the polymer gel or particles shown in Tables 1 to 3.

[0312] (Presence or absence of phase separation structure between thermoplastic elastomer and polymer particles)

[0313] Phase separation was confirmed using AFM.

[0314] (Absolute value of the difference between the SP value of the thermoplastic elastomer and the SP value of the polymer particles)

[0315] The calculation was performed based on the SP values ​​of each described in the aforementioned [Thermoplastic elastomer used] and the SP values ​​of the polymer gels or particles shown in Tables 1 to 3.

[0316] [Evaluation of Development Characteristics]

[0317] <Evaluation of Development Speed>

[0318] The average developed thickness calculated from the plate thickness before and after development was used for the unexposed portion of the flexographic printing plate, and the time required to develop a relief depth (RD): 0.6 mm was converted into the developing time.

[0319] 5: Development time is less than 3 minutes

[0320] 4: Development time is more than 3 minutes and less than 5 minutes

[0321] 3: Development time is more than 5 minutes and less than 7 minutes

[0322] 2: Development time is more than 7 minutes and less than 10 minutes

[0323] 1: Development time is more than 10 minutes

[0324] 〔Evaluation of Flexographic Printing Plate〕

[0325] A flexographic printing plate was used for plate evaluation.

[0326] <Evaluation of Dimensional Stability>

[0327] The thickness of the relief surface of a 600 mm x 600 mm flexographic printing plate was measured while moving about 150 mm at a time in the longitudinal and / or lateral directions from the edge of the flexographic printing plate. The thickness was measured at 16 locations in total and the standard deviation was calculated. The evaluation criteria are shown below.

[0328] In the following evaluation criteria, a value of 3 or more was evaluated as being able to be used practically without any problem.

[0329] [Evaluation criteria]

[0330] 5: 3 times the standard deviation of the thickness of 10 locations is less than 6

[0331] 4: 3 times the standard deviation of the thickness of 10 locations is 6 or more and less than 9

[0332] 3: 3 times the standard deviation of the thickness of 10 locations is 9 or more and less than 12

[0333] 2: 3 times the standard deviation of the thickness of 10 locations is 12 or more and less than 15

[0334] 1: 3 times the standard deviation of thickness at 10 locations is 15 or more

[0335] <Evaluation of whiteout depth>

[0336] The depth of the concave lines having a width of 100 μm of the flexographic printing plate was measured.

[0337] In order to maintain excellent printing quality for a long time, a case where the depth of the concave line is deep is evaluated as good.

[0338] In the following evaluation criteria, a value of 3 or more was evaluated as being able to be used practically without any problem.

[0339] [Evaluation criteria]

[0340] 5: The depth of the concave line is 60μm or more

[0341] 4: The depth of the concave line is 55 μm or more and less than 60 μm

[0342] 3: The depth of the concave line is 50 μm or more and less than 55 μm

[0343] 2: The depth of the concave line is 45 μm or more and less than 50 μm

[0344] 1: The depth of the concave line is less than 45μm

[0345] [Table 1]

[0346]

[0347] [Table 2]

[0348]

[0349] [Table 3]

[0350]

[0351] Industrial Applicability

[0352] The method for producing a flexographic printing plate of the present invention has industrial applicability in a wide range of general commercial printing fields.

Claims

1. A method for producing a flexographic printing plate, comprising a developing step of grinding the plate surface with a brush while supplying an organic solvent-based developer to the plate surface of a flexographic printing original plate on which at least a support, a photosensitive resin composition layer and an infrared ablation layer are sequentially laminated, The organic solvent-based developer contains a polymer gel. The polymer gel is composed of polymers. The polymer gel does not dissolve in the organic solvent-based developer and exists in a dispersed state. The polymer gel is particles having a number average particle size of 40 nm or more and 400 nm or less measured in a state dispersed in the organic solvent-based developer. The organic solvent-based developer contains 0.1 mass % or more and 10.0 mass % or less of the polymer gel, The content of the polymer gel is the ratio of the mass of the polymer gel that does not contain the organic solvent-based developer to the total mass of the organic solvent-based developer.

2. The method for producing a flexographic printing plate according to claim 1, wherein: The absolute value of the difference between the solubility parameter of the organic solvent in the organic solvent-based developer and the solubility parameter of the polymer gel is 0.5 (cal / cm 3 ) 1 / 2 Above and 4.0(cal / cm 3 ) 1 / 2 the following.

3. The method for producing a flexographic printing plate according to claim 1, wherein: The photosensitive resin composition layer contains a thermoplastic elastomer.

4. The method for producing a flexographic printing plate according to claim 1, wherein: The photosensitive resin composition layer contains a thermoplastic elastomer and polymer particles.

5. The method for producing a flexographic printing plate according to claim 4, wherein: The photosensitive resin composition layer has a dispersed phase and a continuous phase. Any one of the thermoplastic elastomer and the polymer particles forms the continuous phase or the dispersed phase.

6. The method for producing a flexographic printing plate according to claim 4, wherein: The absolute value of the difference between the solubility parameter of the thermoplastic elastomer and the solubility parameter of the polymer particles is 0.1 (cal / cm 3 ) 1 / 2 Above and 2.0(cal / cm 3 ) 1 / 2 the following.

7. The method for producing a flexographic printing plate according to claim 1, wherein: The organic solvent-based developer contains alcohols and one or more selected from the group consisting of fatty acid esters, hydrocarbons, and chlorine-based organic solvents.

8. A printing method comprising the following steps: A step of obtaining a flexographic printing plate, the step comprising the method for producing a flexographic printing plate according to any one of claims 1 to 7, and performing a printing process using the flexographic printing plate.

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