JP2022119359A - Flexo printing original plate and method for manufacturing the same - Google Patents

Abstract

To provide a flexo printing original plate without deforming a side surface even when pressurizing, for example, the end surface the flexo printing original plate so as to be represented by chucking, and a method for manufacturing the same.SOLUTION: A flexo printing original plate includes a laminate obtained by laminating at least, a support, a photosensitive resin composition layer and an infrared ablation layer in this order. The photosensitive resin composition layer of the laminate has a shape including a surface on the side of the support, a surface on the side of the infrared ablation layer and four side surfaces, and in the photosensitive resin composition layer, at least one side surface in the four side surfaces is cured or the at least one side surface and the surface on the side of the support are cured.SELECTED DRAWING: Figure 1

Description

The present invention relates to a flexographic printing original plate and a method for producing a flexographic printing original plate.

Flexographic printing is a type of letterpress printing, and has the advantage of being applicable to various substrates because it uses a soft material such as rubber or synthetic resin for the flexographic printing plate.
Conventional methods for producing flexographic printing plates used in flexographic printing include plate making using negative film and computer plate making technology ( hereinafter also referred to as “CTP technology”).
In recent years, the method using the CTP technology has become mainstream because the method using the CTP technology does not require a negative film manufacturing process and can reduce the cost and the time required for manufacturing the negative film.

When using the CTP technique, the original plate of the flexographic printing plate (hereinafter also referred to as "flexographic printing original plate") is generally a substrate such as polyethylene terephthalate (hereinafter also referred to as "PET"), and a photosensitive resin composition A material layer, a protective layer (barrier layer), and an infrared ablation layer are laminated in this order.
A flexographic printing plate using the CTP technique is produced, for example, as follows.

First, by irradiating the infrared ablation layer on the photosensitive resin composition layer with a laser for drawing, a part of the infrared ablation layer is removed to prepare an image mask.
Next, ultraviolet rays are simultaneously irradiated from both the substrate side such as PET and the image mask side to form a uniform cured layer on the substrate side and cure only the portions where the infrared ablation layer has been removed on the image mask side. Lay layers.
After that, the uncured layer in the photosensitive resin composition layer is removed to form a relief image, which is a desired image, to obtain a flexographic printing plate.

As a method of irradiating the infrared ablation layer with a laser for drawing, the flexographic printing original plate is wound around a roll called a drum roll and fixed, and the desired image mask is obtained by rotating the roll while scanning the laser in the roll axial direction. is generally used.

In the preparation of the flexographic printing plate as described above, if the periphery of the unexposed plate is tacky, it is very inconvenient to handle. For example, when taking out the unexposed plate from the packing case, the periphery of the unexposed plate adheres to the packaging or cushion sheet, when cutting, the periphery of the unexposed plate adheres to the cutting table, In addition, the periphery of the unexposed plate adheres to the exposure table or the vacuum contact sheet. In addition, problems such as adhesion of dust to the periphery of the unexposed plate and adhesion of unexposed resin to hands during operation occur.

As a method for solving such a problem, for example, Patent Document 1 discloses that the periphery of an unexposed photosensitive resin plate is irradiated with light having a wavelength of 300 nm or less to eliminate the stickiness of the side surface of the flexographic printing plate. A method has been proposed to do so.

JP-A-5-94026

When the flexographic printing plate is fixed to the drum roll, the end face of the flexographic printing plate is chucked with a clamp. becomes inconvenient. For example, resin may adhere to the drum roll when removing the original flexographic printing plate from the drum roll, or may adhere to the glass table during the exposure process. Also, when the plate is moved, problems such as the plate being caught in the adhered resin and being bent may occur.
However, the method described in Patent Document 1 only eliminates the adhesiveness of the side surfaces of the flexographic printing plate, and cannot prevent deformation of the side surface of the original flexographic printing plate due to the pressure during chucking.
Therefore, in the production of a flexographic printing plate, for example, the development of a flexographic printing plate precursor that does not deform the side surfaces even when pressure is applied to the end faces of the flexographic printing plate precursor when it is fixed to a drum roll is desired.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a flexographic printing original plate in which the side faces are not deformed even when pressure is applied to the end surfaces of the flexographic printing original plate as typified by chucking, and a method for producing the same.

The present inventors have made intensive research to solve the above problems, and found that at least one side surface of the photosensitive resin composition layer in the flexographic printing original plate is irradiated with light having a wavelength of 340 nm or more to cure the side surface. As a result, the present inventors have found that a flexographic printing original plate can be obtained that does not deform even when pressure is applied to the end faces, and have completed the present invention.
That is, the present invention relates to the following.
[1]
A flexographic printing original plate comprising a laminate in which at least a support, a photosensitive resin composition layer, and an infrared ablation layer are laminated in this order,
The photosensitive resin composition layer of the laminate has a shape having a support side surface, an infrared ablation layer side surface, and four side surfaces, and in the photosensitive resin composition layer, among the four side surfaces, at least A flexographic printing master which is hardened on one side or hardened on at least one side and the side facing the support.
[2]
The original flexographic printing plate according to [1], wherein at least two of the four side surfaces of the photosensitive resin composition layer of the laminate are cured.
[3]
The original flexographic printing plate according to [1] or [2], wherein all sides of the photosensitive resin composition layer of the laminate are cured.
[4]
The flexo according to any one of [1] to [3], wherein in the photosensitive resin composition layer of the laminate, the distance from the surface of the cured side surface to the cured portion in the inner direction of the layer is 1 mm or more and 20 mm or less. Original print.
[5]
In the photosensitive resin composition layer of the laminate, the cured surface is one or more side surfaces, and the distance from the surface of the side surface to the cured portion in the direction inside the layer is 1 mm or more and 20 mm or less [1] The original flexographic printing plate according to any one of [4].
[6]
a step of laminating at least a support, a photosensitive resin composition layer, and an infrared ablation layer in this order to obtain a laminate;
The photosensitive resin composition layer of the laminate has a shape having a support side surface, an infrared ablation layer side surface, and four side surfaces, and at least one side surface of the photosensitive resin composition layer has a wavelength of 340 nm or more. A method for producing a flexographic printing original plate, comprising the step of curing the side surface by irradiating with light of.
[7]
The method for producing a flexographic printing original plate according to [6], wherein in the step of curing the side surface, the distance from the surface of the side surface to the cured portion in the layer-inward direction is 1 mm or more and 20 mm or less.
[8]
[6] or [ 7].

ADVANTAGE OF THE INVENTION According to this invention, even if pressure is applied to the flexographic printing original plate edge surface so that chucking may be represented, the side surface does not deform|transform, and the flexographic printing original plate can be provided.

FIG. 1 is a cross-sectional view schematically showing an example of the original flexographic printing plate of the present invention. FIG. 2 is a cross-sectional view schematically showing another example of the original flexographic printing plate of the present invention. FIG. 3 is a perspective view schematically showing an example of the original flexographic printing plate of the present invention. FIG. 4 is a perspective view schematically showing another example of the original flexographic printing plate of the present invention. FIG. 5 is a perspective view schematically showing still another example of the original flexographic printing plate of the present invention. FIG. 6 is a perspective view schematically showing still another example of the original flexographic printing plate of the present invention. FIG. 7 is a perspective view schematically showing still another example of the original flexographic printing plate of the present invention. FIG. 8 is a conceptual diagram showing an example of the manufacturing process of the flexographic printing original plate of the present invention. FIG. 9 is a conceptual diagram showing another example of the manufacturing process of the flexographic printing original plate of the present invention. FIG. 10 is a conceptual diagram showing an example of the halftone dot formation process.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail.
The present invention is not limited to the following description, and various modifications are possible within the scope of the gist thereof.

(Flexographic printing original plate)
The flexographic printing original plate of the present embodiment includes at least a laminate in which a support, a photosensitive resin composition layer, and an infrared ablation layer are laminated in this order, and the photosensitive resin composition layer of the laminate is , a surface on the side of the support, a surface on the side of the infrared ablation layer, and four side surfaces, and in the photosensitive resin composition layer, at least one side surface of the four side surfaces is cured, or At least one side surface and the surface facing the support are hardened.
Specific examples of the flexographic printing original plate of the present embodiment include, for example, a support 1, a photosensitive resin composition layer having cured portions 2 and uncured portions 3 on two opposite sides as shown in FIG. Examples include a laminate in which layers 4 are laminated in this order, and as shown in FIG. A laminate in which a photosensitive resin composition layer having a portion 3 and an infrared ablation layer 4 are laminated in this order is exemplified.
As the ultraviolet rays irradiated to cure the support-side surface and side surfaces of the photosensitive resin composition layer, ultraviolet rays of 340 nm or more can be used, and ultraviolet rays of 340 to 400 nm can be particularly preferably used.
The light source is not particularly limited, but for example, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, zirconium lamps, carbon arc lamps, ultraviolet fluorescent lamps, UV-LEDs, etc. can be used.
The ultraviolet irradiation method for curing the support-side surface and side surface of the photosensitive resin composition layer is not particularly limited. A method of installing and irradiating ultraviolet rays from the infrared ablation layer side, a method of installing a light source on the side surface side of the photosensitive resin composition layer and irradiating ultraviolet rays from the side surface side of the photosensitive resin composition layer, and an irradiation area There is a method in which a light source having an area equal to or larger than the area of the support is installed on the side of the support and ultraviolet rays are irradiated from the side of the support.
Among the above ultraviolet irradiation methods, when ultraviolet rays are irradiated from the support side, the side surface of the photosensitive resin composition layer is cured, and in addition, a uniform cured layer is formed on the support side surface of the photosensitive resin composition layer. be. In the method of irradiating ultraviolet light from the infrared ablation layer side and the method of irradiating ultraviolet light from the side surface side of the photosensitive resin composition layer, only the side surface irradiated with ultraviolet light can be cured in a limited manner.

Curing of the photosensitive resin composition layer generally refers to a phenomenon in which a photopolymerizable monomer and a photopolymerization initiator, which will be described later, undergo a polymerization reaction to form a polymer. In the present embodiment, curing or uncuring of the photosensitive resin composition layer is performed using Fourier transform infrared spectroscopy (hereinafter also referred to as “FTIR”), as described in the examples below. Determination is performed by comparing the absorbance peak values at specific wavelengths due to the specific functional groups of the monomers. Specifically, when the peak value of absorbance at a specific wavelength in the photosensitive resin composition layer after UV irradiation is less than half the peak value of absorbance at a specific wavelength in the photosensitive resin composition layer before UV irradiation, The photosensitive resin composition layer is determined to be cured.

Of the four sides of the photosensitive resin composition layer used in the flexographic printing original plate of the present embodiment, at least two sides facing each other are preferably cured. By using such a photosensitive resin composition layer, the flexographic printing original plate of the present embodiment tends to further exhibit the effect of suppressing lateral deformation when pressure is applied.

Further, it is preferable that all sides of the photosensitive resin composition layer used in the flexographic printing original plate of the present embodiment are cured. By using such a photosensitive resin composition layer, the flexographic printing original plate of the present embodiment tends to further exhibit the effect of suppressing lateral deformation when pressure is applied.

Further, in the photosensitive resin composition layer used in the flexographic printing original plate of the present embodiment, the distance from the surface of the cured side surface to the cured portion in the layer inner direction is preferably 1 mm or more and 20 mm or less, and 1 mm or more and 15 mm or less. is more preferably 1 mm or more and 10 mm or less. In the flexographic printing original plate of the present embodiment, the distance of the cured portion on the side surface of the photosensitive resin composition layer is within the above range, so that a wider image area can be obtained while maintaining the effect of suppressing side deformation when pressure is applied. can be secured. The image area refers to the image portion used for transfer to the printing material, and if there is a cured portion of the photosensitive resin composition layer in the image of the flexographic printing original plate, the desired image may not be formed.

Further, in the photosensitive resin composition layer used in the flexographic printing original plate of the present embodiment, when the surface on the support side is cured, the distance from the surface of the support side surface to the cured portion in the layer inner direction is flexographic printing. It is preferably 10% or more and 90% or less, more preferably 10% or more and 80% or less, and even more preferably 10% or more and 70% or less of the total thickness of the original plate. The flexographic printing original plate of the present embodiment tends to be able to increase the relief depth of the flexographic printing plate by setting the distance of the cured portion of the surface of the photosensitive resin composition layer on the support side within the above range. The depth of relief refers to the distance between the top surface of dots and the surface of a flat portion without dots when an image is formed.

In the present embodiment, the distance of the cured portion is specifically, for example, in the case of the side surface of the photosensitive resin composition layer, the direction from the surface of the cured side surface to the inside of the layer and the support side. It is the distance in the direction parallel to the surface, and in the case of the support side surface in the photosensitive resin composition layer, the direction from the surface of the cured support side surface to the inside of the layer and perpendicular to the support side surface is the distance in the direction Further, in this embodiment, the distance of the cured portion can be measured by the method described in Examples below.

In addition, in the photosensitive resin composition layer used in the flexographic printing original plate of the present embodiment, it is preferable that one or more side surfaces and the support surface are cured, and more preferably only one or more side surfaces are cured. preferable. Specific examples of the flexographic printing original plate in which one or more side surfaces and the support surface of the photosensitive resin composition layer are cured include, for example, all side surfaces and the support surface of the photosensitive resin composition layer that are cured. A flexographic printing original plate as shown in FIG. 6 can be mentioned. Further, as the flexographic printing original plate in which only the side surface of the photosensitive resin composition layer is cured, specifically, for example, a flexographic printing original plate as shown in FIG. 3 in which one side surface is cured, a photosensitive resin Examples include a flexographic printing original plate as shown in FIG. 4 in which two opposing sides of the composition layer are cured, and a flexographic printing original plate as shown in FIG. 5 in which all sides of the photosensitive resin composition layer are cured. In the flexographic printing original plate of the present embodiment, for example, as shown in FIGS. 3 to 5, only the side surface of the photosensitive resin composition layer is cured, so that the effect of suppressing side surface deformation when pressure is applied is further increased. It tends to be expressed and to be excellent in halftone dot formation. As shown in FIG. 10, the halftone dot formability is defined by irradiating the portion of the black mask enclosed by the dashed line with a laser beam, then exposing the uncured resin to UV light to obtain a cured resin, washing the resin, and forming dots. It is a property of how much the laser-irradiated area and the area of the top surface of the formed dots match when forming halftone dots arranged at regular intervals.

In the photosensitive resin composition layer used in the flexographic printing original plate of the present embodiment, the cured surface is one or more side surfaces, and the distance from the surface of the side surface to the cured portion in the layer inner direction is 1 mm or more and 20 mm. It is preferably 1 mm or more and 15 mm or less, and even more preferably 1 mm or more and 10 mm or less. In the flexographic printing original plate of the present embodiment, the distance of the cured portion in the photosensitive resin composition layer is within the above range, so that a wider image area is secured while maintaining the effect of suppressing lateral deformation when pressure is applied. be able to.

Further, in the present embodiment, by preparing a light source having a sufficient irradiation area with respect to the size of the photosensitive resin composition layer, the flexographic printing original plate of the present embodiment can be formed. Although the size is not particularly limited, for example, length: 400 mm or more and 2200 mm or less and width: 400 mm or more and 2200 mm or less are practically common.

(support)
The support used in the flexographic printing original plate of the present embodiment is not particularly limited, but examples thereof include polypropylene films, polyethylene films, polyester films such as polyethylene terephthalate and polyethylene naphthalate, and polyamide films. .
As the support, a dimensionally stable film having a thickness of 75 μm to 300 μm is preferable, and a polyester film is particularly preferable.
Moreover, it is preferable to have an adhesive layer on the support.
The material of the adhesive layer is not particularly limited, but examples thereof include a resin composition containing a binder polymer such as polyurethane, polyamide, or thermoplastic elastomer, and an adhesive active ingredient such as an isocyanate compound or an ethylenically unsaturated compound. be done.
In addition, various auxiliary additives can be added to the adhesive layer. Examples of the auxiliary additive component include, but are not limited to, plasticizers, thermal polymerization inhibitors, ultraviolet absorbers, antihalation agents, light stabilizers, photopolymerization initiators, photopolymerizable monomers, and dyes.
Further, in order to obtain a higher adhesive strength between the adhesive layer and the support, it is more preferable to provide at least one or more undercoat layers.

(Photosensitive resin composition layer)
The photosensitive resin composition layer used in the flexographic printing original plate of this embodiment is useful for all of solvent development, water development, and heat development.
Although the material of the photosensitive resin composition layer is not particularly limited, for example, a photosensitive resin composition containing (a) a thermoplastic elastomer, (c) a photopolymerizable monomer, and (d) a photopolymerization initiator is suitable. can be mentioned.
The photosensitive resin composition layer preferably further contains (b) a hydrophilic copolymer when the development step is performed in an aqueous cleaning solution.
Although the compounds (a) to (d) are not particularly limited, for example, the compounds described in "JP-A-2018-120131" can be used.

<(a) Thermoplastic elastomer>
(a) The thermoplastic elastomer is preferably a thermoplastic elastomer containing at least one polymer block mainly composed of a conjugated diene and at least one polymer block mainly composed of a vinyl aromatic hydrocarbon.

As used throughout this specification, the term "mainly" means at least 60% by weight in a polymer block.
In the polymer block mainly composed of conjugated diene, the conjugated diene accounts for preferably 80% by mass or more, more preferably 90% by mass or more in the polymer block.

Examples of conjugated dienes include, but are not limited to, 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 and chloroprene monomers, and 1,3-butadiene is particularly preferred from the viewpoint of wear resistance. These monomers may be used singly or in combination of two or more.
The vinyl content, such as the content of 1,2-butadiene and 3,4-isoprene, in the total amount of conjugated dienes in the polymer block mainly composed of conjugated dienes is not particularly limited. From the viewpoint of printing plate formability, the vinyl content is preferably 5 mol % to 50 mol %, more preferably 8 mol % to 50 mol %, even more preferably 10 mol % to 40 mol %.

The number average molecular weight of the polymer block mainly composed of conjugated diene is preferably from 20,000 to 250,000, more preferably from 30,000 to 200,000, more preferably from 40,000 to 150,000, from the viewpoint of printing durability. is more preferred.

The conjugated diene-based polymer block may contain alkylene units. The method of introducing the alkylene unit is not particularly limited, but a method of polymerizing using a monoolefin such as ethylene or butylene as a raw material monomer for a polymer block mainly composed of a conjugated diene, or a method of hydrogenating a conjugated diene polymer block. etc. In particular, from the viewpoint of availability, a method of hydrogenating a polymer block mainly composed of a conjugated diene is preferred.
The content of alkylene units in the polymer block mainly composed of conjugated diene is preferably 5 mol % or more from the viewpoint of solvent resistance, and preferably 50 mol % or less from the viewpoint of ensuring transparency of the photosensitive resin composition. A range of 10 mol % to 35 mol % is more preferred, and a range of 10 mol % to 25 mol % is even more preferred.

The alkylene unit is preferably contained in a polymer block mainly composed of butadiene. Further, it is more preferable to hydrogenate the polymer block part mainly composed of butadiene so that it contains all of 1,4-butadiene units, 1,2-butadiene (vinyl) units and butylene (alkylene) units. preferable. Further, in the polymer block mainly composed of butadiene, at least 25 mol % to 70 mol % of 1,4-butadiene units, 0 mol % to 50 mol % of 1,2-butadiene (vinyl) units, and 10 mol % to 10 mol % of butylene units It is more preferable to contain in the range of 50 mol %.

The conjugated diene, the vinyl content of the conjugated diene, and the content and ratio of the vinyl aromatic hydrocarbon can be measured using a nuclear magnetic resonance spectrometer ( ¹ H-NMR).

Examples of vinyl aromatic hydrocarbons include, but are not limited to, styrene, t-butylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl- Monomers such as p-aminoethylstyrene, vinylpyridine, p-methylstyrene, tertiary butylstyrene, α-methylstyrene, and 1,1-diphenylethylene are included. In particular, styrene is preferred because it allows a flexographic printing original plate to be smoothly molded at a relatively low temperature (hereinafter referred to as high moldability). These monomers may be used singly or in combination of two or more.

The number average molecular weight of the polymer block mainly composed of vinyl aromatic hydrocarbons is preferably 100,000 or less from the viewpoint of preventing the orientation of the printing plate, and from the viewpoint of chipping resistance during plate making and printing. , 3,000 or more. The number average molecular weight of the polymer block mainly composed of vinyl aromatic hydrocarbon is more preferably in the range of 5,000 to 80,000, more preferably in the range of 5,000 to 60,000.

The content of the vinyl aromatic hydrocarbon in the block copolymer increases the moldability of the photosensitive resin composition, the high resistance to chipping of the convex portions of the printing plate, and the hardness of the printing plate when the ink component adheres. From the viewpoint of maintenance, it is preferable to make it 25% by mass or less. On the other hand, from the viewpoint of increasing the cold flow resistance of the flexographic printing original plate of the present embodiment, the content of the vinyl aromatic hydrocarbon in the block copolymer is preferably 13% by mass or more. A range of 15% by mass to 24% by mass is more preferable, and a range of 16% by mass to 23% by mass is even more preferable.

The content of (a) the thermoplastic elastomer in the photosensitive resin composition layer is 15% by mass to 90% by mass when the total amount of the photosensitive resin composition is 100% by mass, from the viewpoint of printing durability during printing. is preferably (a) The content of the thermoplastic elastomer is more preferably 15% by mass to 80% by mass, even more preferably 20% by mass to 75% by mass.

<(b) hydrophilic copolymer>
(b) Hydrophilic copolymers are internally crosslinked polymer particles containing units derived from hydrophilic unsaturated monomers. The polymer particles are not particularly limited. Examples thereof include polymer particles obtained by removing water from a water-dispersed latex in which coalesced particles are dispersed in water as a dispersoid. Units derived from hydrophilic unsaturated monomers may be, for example, 0.1 to 20% by mass, 0.5 to 15% by mass, or 1 to 10% by mass of the total monomers. %.

As the hydrophilic unsaturated monomer, a monomer containing at least one hydrophilic group and an unsaturated double bond is preferred. The hydrophilic unsaturated monomer is not particularly limited, but includes, for example, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, salts thereof, an acid anhydride group, and the like. monomers containing hydroxyl groups and unsaturated double bonds; monomers containing acrylamide and unsaturated double bonds; surfactants containing reactive unsaturated double bonds (monomers ); and the like. These hydrophilic unsaturated monomers may be used singly or in combination of two or more.

Examples of water-dispersed latex include, but are not limited to, acrylonitrile-butadiene copolymer latex, polychloroprene latex, polyisoprene latex, polyurethane latex, (meth)acrylate-butadiene latex, vinylpyridine polymer latex, and butyl polymer latex. , thiocol polymer latex, water-dispersible latex polymers such as acrylate polymer latex, and the like.
These water-dispersed latexes may contain (meth)acrylates, carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, vinylbenzoic acid and cinnamic acid, monobasic acids such as sulfonic acids such as styrenesulfonic acid; itaconic acid; , fumaric acid, maleic acid, citraconic acid, muconic acid, and other dibasic acids;
In the water-dispersed latex, in addition to polymer particles obtained by emulsion polymerization using a hydrophilic unsaturated monomer and, if necessary, other monomers copolymerizable therewith, Furthermore, other polymer particles may be included as dispersoids. Examples of such other polymer particles include, but are not limited to, polybutadiene, natural rubber, and styrene-butadiene copolymer particles.

Among these water-dispersed latexes, water-dispersed latexes containing a butadiene skeleton or an isoprene skeleton in the polymer molecular chain are preferred from the viewpoint of printing durability. For example, polybutadiene latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, and those obtained by copolymerizing (meth)acrylic acid ester, acrylic acid, methacrylic acid, itaconic acid, etc. with these water-dispersed latexes preferable. More preferably, the water-dispersible latex is a styrene-butadiene copolymer, and at least one type of unsaturated monomer containing a (meth)acrylic acid ester, acrylic acid, methacrylic acid, itaconic acid, or the like, containing an acidic functional group. It is a water-dispersed latex of a polymerized copolymer.

The amount of the acidic functional group-containing unsaturated monomer to be used is preferably 1 to 30% by mass based on the total amount of unsaturated monomers used in synthesizing the hydrophilic copolymer (b). When the amount of the acidic functional group-containing unsaturated monomer used is 1% by mass or more, water-based development tends to be facilitated. It is possible to prevent an increase in the amount of swelling of the ink, and to prevent deterioration of workability during mixing of the photosensitive resin composition.

(b) Unsaturated monomers other than the acidic functional group-containing unsaturated monomers that can be used in synthesizing the hydrophilic copolymer include, but are not limited to, conjugated dienes, aromatic group vinyl compound, (meth)acrylic acid ester, ethylenic monocarboxylic acid alkyl ester monomer having a hydroxyl group, unsaturated dibasic acid alkyl ester, maleic anhydride, vinyl cyanide compound, (meth)acrylamide and its derivatives, vinyl esters, vinyl ethers, vinyl halides, basic monomers having amino groups, vinylpyridines, olefins, silicon-containing α,β-ethylenically unsaturated monomers, allyl compounds and the like.

Examples of conjugated dienes include, but are not limited to, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 2-methyl -1,3-butadiene, 1,3-pentadiene, chloroprene, 2-chloro-1,3-butadiene, cyclopentadiene and the like.
Examples of aromatic vinyl compounds include, but are not limited to, styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ethylstyrene, vinyltoluene, vinylxylene, Bromostyrene, vinylbenzyl chloride, pt-butylstyrene, chlorostyrene, alkylstyrene, divinylbenzene, trivinylbenzene and the like.

Examples of (meth)acrylic acid esters include, but are not limited to, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-amyl (meth)acrylate, isoamylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, Octadecyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, 2-ethyl-hexyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxycyclohexyl (Meth)acrylate, glycidyl (meth)acrylate, ethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate , propylene glycol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, tri ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, Tetramethylolmethane tetra(meth)acrylate, allyl(meth)acrylate, bis(4-acryloxypolyethoxyphenyl)propane, methoxypolyethylene glycol (meth)acrylate, β-(meth)acryloyloxyethyl hydrogen phthalate, β- (Meth)acryloyloxyethyl hydrogen succinate, 3-chloro-2-hydroxypropyl (meth)acrylate, stearyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, 2-hydroxy-1 , 3-di(meth)acrylic oxypropane, 2,2-bis[4-((meth)acryloxyethoxy)phenyl]propane, 2,2-bis[4-((meth)acryloxy-diethoxy)phenyl]propane, 2,2-bis[4 -((meth)acryloxy-polyethoxy)phenyl]propane, isobornyl (meth)acrylate and the like.

The ethylene-based monocarboxylic acid alkyl ester monomer having a hydroxyl group is not limited to the following, and examples thereof include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, methacryl 2-hydroxypropyl acid, 1-hydroxypropyl acrylate, 1-hydroxypropyl methacrylate, hydroxycyclohexyl (meth)acrylate and the like.

Examples of unsaturated dibasic acid alkyl esters include, but are not limited to, crotonic acid alkyl esters, itaconic acid alkyl esters, fumaric acid alkyl esters, and maleic acid alkyl esters.

Examples of vinyl cyanide compounds include, but are not limited to, acrylonitrile, methacrylonitrile, and the like.

Examples of (meth)acrylamide and derivatives thereof include, but are not limited to, (meth)acrylamide, N-methylol(meth)acrylamide, N-alkoxy(meth)acrylamide and the like.

Examples of vinyl esters include, but are not limited to, vinyl acetate, vinyl butyrate, vinyl stearate, vinyl laurate, vinyl myristate, vinyl propionate, and vinyl versatic acid.

Examples of vinyl ethers include, but are not limited to, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, amyl vinyl ether, and hexyl vinyl ether.

Examples of vinyl halides include, but are not limited to, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, and vinylidene fluoride.

Examples of the basic monomer having an amino group include, but are not limited to, aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate and the like.

Examples of olefins include, but are not limited to, ethylene.

Examples of silicon-containing α,β-ethylenically unsaturated monomers include, but are not limited to, vinyltrichlorosilane, vinyltriethoxysilane, and the like.

Examples of the allyl compound include, but are not limited to, allyl ester, diallyl phthalate, and the like.
In addition, monomers having 3 or more double bonds such as triallyl isocyanurate can also be used.

These monomers may be used singly or in combination of two or more. The mass ratio of the acidic functional group-containing unsaturated monomer and the other monomer (acidic functional group-containing unsaturated monomer/other monomer) is preferably 5/95 to 95/5, and more It is preferably 50/50 to 90/10.
When the mass ratio (unsaturated monomer containing an acidic functional group/other monomer) is 5/95 to 95/5, the rubber elasticity of the photosensitive resin composition can be improved in practice. can.

(b) The hydrophilic copolymer is preferably a polymer synthesized by emulsion polymerization. In this case, the emulsifier (surfactant) used during polymerization is preferably a reactive emulsifier.

As the reactive emulsifier, a reactive emulsifier containing a radically polymerizable double bond, a hydrophilic functional group and a hydrophobic group in its molecular structure and having emulsifying, dispersing and wetting functions like common emulsifiers is preferred. . (b) When emulsifying a hydrophilic copolymer, the reactive emulsifier is added to 100 parts by mass of the acidic functional group-containing unsaturated monomer and other monomers excluding the reactive emulsifier. It is preferable to use an emulsifier (surfactant) capable of synthesizing a polymer having an average particle size of 5 to 500 nm when used in an amount of 0.1 part by mass or more.

The structure of the radically polymerizable double bond in the molecular structure of the reactive emulsifier is not particularly limited, but examples thereof include vinyl groups, acryloyl groups, and methacryloyl groups.
The hydrophilic functional group in the molecular structure of the reactive emulsifier is not particularly limited, but examples include anionic groups such as sulfate, nitrate, phosphate, borate, and carboxyl groups; a polyoxyalkylene chain structure such as polyoxyethylene, polyoxymethylene, polyoxypropylene; or a hydroxyl group.
The hydrophobic group in the molecular structure of the reactive emulsifier is not particularly limited, but examples thereof include an alkyl group and a phenyl group.

Reactive emulsifiers include anionic emulsifiers, nonionic emulsifiers, cationic emulsifiers, amphoteric emulsifiers, etc., depending on the type of hydrophilic functional group contained in their structure. Moreover, each of the radically polymerizable double bond, the hydrophilic functional group and the hydrophobic group in the molecular structure may contain a plurality of types.

Commercially available surfactants can be used as reactive emulsifiers. Examples of commercially available anionic surfactants include, but are not limited to, Adekari Soap SE (manufactured by ADEKA) and Aqualon HS. and BC and KH (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Latemul S (manufactured by Kao Corporation), Antox MS (manufactured by Nippon Emulsion Co., Ltd.), Adekaria Soap SDX and PP (manufactured by ADEKA), Hitenol A (Dai-ichi Kogyo Seiyaku Co., Ltd.) (manufactured by Sanyo Chemical Industries, Ltd.), Eleminol RS (manufactured by Sanyo Chemical Industries, Ltd.), Spinomer (manufactured by Tosoh Organic Chemical Co., Ltd.), and the like. Examples of commercially available nonionic surfactants include, but are not limited to, Aqualon RN, Neugen N (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adekari Soap NE (manufactured by ADEKA), and the like.
These may be used individually by 1 type, and may be used in combination of 2 or more types.

The amount of the reactive emulsifier to be used is preferably in the range of 1 to 20 parts by mass with respect to 100 parts by mass of the hydrophilic copolymer (b) calculated from the charged amount of raw materials. When the amount of the reactive emulsifier is 1 part by mass or more, the image reproducibility of the resulting printing plate tends to improve, and when the amount is 20 parts by mass or less, the printing resistance of the resulting printing plate tends to improve. be.

(b) When synthesizing the hydrophilic copolymer by emulsion polymerization, a non-reactive emulsifier can be used as necessary.
Examples of non-reactive emulsifiers include, but are not limited to, anionic surfactants such as fatty acid soaps, rosin acid soaps, sulfonates, sulfates, phosphates, polyphosphates, and acyl salicodinates. cationic surfactants such as nitrilated fat derivatives, fat derivatives, fatty acid derivatives, α-olefin derivatives; alcohol ethoxylates, alkylphenol ethoxylates, propoxylates, aliphatic alkanolamides, alkyl polyglycosides, polyoxyethylene sorbitan fatty acid esters, Nonionic surfactants such as oxyethyleneoxypropylene block copolymers are included. These may be used individually by 1 type, and may be used in combination of 2 or more types.

Examples of sulfonates include, but are not limited to, alkylsulfonates, alkylsulfates, alkylsulfosuccinates, polyoxyethylene alkylsulfates, sulfonated fats and oils, alkyldiphenylether disulfonates, α -olefin sulfonate, alkyl glyceryl ether sulfonate, N-acylmethyl taurate and the like.

Other examples of non-reactive emulsifiers include, but are not limited to, those described in "Surfactant Handbook (Takahashi, Namba, Koike, Kobayashi: Kogaku Tosho, 1972)".

The amount of the non-reactive emulsifier used is preferably less than 1 part by mass with respect to 100 parts by mass of the hydrophilic copolymer (b) calculated from the charged amount of raw materials. When the amount of the non-reactive emulsifier used is less than 1 part by mass, the obtained printing plate has an appropriate water swelling rate, and deterioration of abrasion resistance when ink adheres and image reproducibility after moisture absorption are prevented. can be prevented.

(b) As a method for emulsion polymerization of a hydrophilic copolymer, a predetermined amount of water, an emulsifier, and other additives are charged in advance to a reaction system adjusted to a temperature at which polymerization is possible, and a polymerization initiator and unsaturated Monomers, emulsifiers, modifiers, and the like are generally added to the reaction system in a batch operation or a continuous operation. It is also a commonly used method to previously charge predetermined amounts of seed latex, polymerization initiator, unsaturated monomers and other modifiers to the reaction system as necessary. In addition, by devising a method of adding unsaturated monomers, emulsifiers, other additives, and modifiers to the reaction system, it is possible to change the layer structure of the synthesized hydrophilic copolymer particles step by step. is.
In this case, physical properties representing the structure of each layer include hydrophilicity, glass transition temperature, molecular weight, crosslink density, and the like. Moreover, the number of stages of this layer structure is not particularly limited.

(b) A known chain transfer agent can be used in the step of polymerizing the hydrophilic copolymer.
As the chain transfer agent, a chain transfer agent containing elemental sulfur can be preferably used. Examples of chain transfer agents containing sulfur include, but are not limited to, alkanethiols such as t-dodecylmercaptan and n-dodecylmercaptan; thioalkyl alcohols such as mercaptoethanol and mercaptopropanol; thioglycolic acid; , thioalkylcarboxylic acids such as thiopropionic acid; thiocarboxylic acid alkyl esters such as octyl thioglycolate and octyl thiopropionate; sulfides such as dimethylsulfide and diethylsulfide;
Other chain transfer agents include, but are not limited to, halogenated hydrocarbons such as terpinolene, dipentene, t-terpinene, and carbon tetrachloride.
Among these chain transfer agents, alkanethiols are preferred because they have a high chain transfer rate and the obtained hydrophilic copolymer (b) has a good balance of physical properties.

These chain transfer agents may be used singly or in combination of two or more.
These chain transfer agents are mixed with the monomer and supplied to the reaction system, or added alone at a predetermined time and in a predetermined amount. The amount of these chain transfer agents to be used is preferably 0.1 to 10% by mass based on the total amount of unsaturated monomers used in the polymerization of the hydrophilic copolymer (b).
When the amount of the chain transfer agent used is 0.1% by mass or more, the processability when mixing the photosensitive resin composition becomes good, and when it is 10% by mass or less, (b) hydrophilic The molecular weight of the copolymer can be made practically sufficient.

(b) A polymerization reaction inhibitor can be used for the polymerization of the hydrophilic copolymer, if necessary.
A polymerization reaction inhibitor is a compound that reduces the radical polymerization rate by being added to an emulsion polymerization system. Polymerization reaction inhibitors are more specifically polymerization rate retarders, polymerization inhibitors, chain transfer agents with low radical reinitiation reactivity, and monomers with low radical reinitiation reactivity. Polymerization reaction inhibitors are generally used to adjust the polymerization reaction rate and latex physical properties. These polymerization reaction inhibitors are added to the reaction system by batch operation or continuous operation. When a polymerization reaction inhibitor is used, the strength of the latex coating in the photosensitive resin composition is improved, and the printing durability is improved. Although the details of the reaction mechanism are unknown, the polymerization reaction inhibitor is thought to be closely involved in the steric structure of the (b) hydrophilic copolymer, and is thus effective in adjusting the physical properties of the latex coating. presumed to be

Examples of polymerization reaction inhibitors include, but are not limited to, quinones such as o-, m-, or p-benzoquinone; nitrobenzene, nitros such as o-, m-, or p-dinitrobenzene; compounds; amines such as diphenylamine; catechol derivatives such as tertiary-butylcatechol; 1,1-diphenylethylene or α-methylstyrene, 1,1- disubstituted vinyl compounds; 1,2-disubstituted vinyl compounds such as 2,4-diphenyl-4-methyl-2-pentene and cyclohexene; and the like. In addition, "POLYMER HANDBOOK 3rd Ed. (J. Brandup, E.H. Immergut: John Wiley & Sons, 1989)", "Revised polymer synthesis chemistry (Otsu: Kagaku Dojin, 1979)" Compounds described as inhibitors or polymerization inhibitors can be mentioned.
Among these, 2,4-diphenyl-4-methyl-1-pentene (α-methylstyrene dimer) is particularly preferred from the viewpoint of reactivity. These polymerization reaction inhibitors may be used singly or in combination of two or more.
The amount of these polymerization reaction inhibitors to be used is preferably 10% by mass or less with respect to the total amount of unsaturated monomers used in the polymerization of the hydrophilic copolymer (b). By making it 10% by mass or less, there is a tendency that a practically sufficient polymerization rate can be obtained.

The radical polymerization initiator, which is a preferred example of the polymerization initiator used in the polymerization of the hydrophilic copolymer (b), is radically decomposed in the presence of heat or a reducing substance to cause addition polymerization of the monomer. Both inorganic and organic initiators can be used.
Examples of the radical polymerization initiator include, but are not limited to, water-soluble or oil-soluble peroxodisulfates, peroxides, azobis compounds, etc. Specifically, potassium peroxodisulfate , sodium peroxodisulfate, ammonium peroxodisulfate, hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide, 2,2′-azobisbutyronitrile, cumene hydroperoxide and the like.
Examples of the radical polymerization initiator include POLYMER HANDBOOK (3rd edition), J. Am. Brandrup and E.M. H. Compounds described in Immergut, John Willy & Sons (1989) can also be used.
A so-called redox polymerization method can also be employed in which a reducing agent such as sodium acid sulfite, ascorbic acid or its salts, erythorbic acid or its salts, or Rongalit is used in combination with a polymerization initiator.
Among these, peroxodisulfate is suitable as a polymerization initiator.
The amount of the polymerization initiator to be used is generally in the range of 0.1 to 5.0% by mass, preferably 0.1% by mass, based on the total amount of unsaturated monomers used in the polymerization of the hydrophilic copolymer (b). It is selected from the range of 2 to 3.0% by mass.
When the amount of the polymerization initiator used is 0.1% by mass or more, high stability is obtained during the synthesis of the hydrophilic copolymer (b), and the amount of the polymerization initiator used is 5.0% by mass or less. With this, the moisture absorption amount of the photosensitive resin composition can be suppressed within a practically favorable range.

(b) When synthesizing the hydrophilic copolymer, various polymerization modifiers can be added as necessary.
Examples of the pH adjuster include, but are not limited to, sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium hydrogen carbonate, sodium carbonate, disodium hydrogen phosphate, and the like. can be added as an agent.
Various chelating agents such as sodium ethylenediaminetetraacetate may also be added as polymerization modifiers.
Furthermore, other additives include, but are not limited to, alkali-sensitive latex, viscosity reducers such as hexametaphosphoric acid, water-soluble polymers such as polyvinyl alcohol and carboxymethylcellulose, thickeners, various anti-aging agents, and ultraviolet rays. Absorbents, antiseptics, disinfectants, antifoaming agents, dispersants such as sodium polyacrylate, water-resistant agents, metal oxides such as zinc oxide, isocyanate compounds, cross-linking agents such as epoxy compounds, lubricants, water retention agents, etc. Various additives may be added.
The method of adding these additives is not particularly limited, and they can be added during or after the synthesis of the hydrophilic copolymer (b).

(b) The polymerization temperature for emulsion polymerization of the hydrophilic copolymer is usually selected in the range of 60 to 120°C.
Alternatively, the polymerization may be carried out at a lower temperature by the redox polymerization method or the like. Furthermore, as the redox catalyst, a metal catalyst such as divalent iron ions, trivalent iron ions, copper ions, etc. may coexist.

(b) The hydrophilic copolymer is preferably particulate and has an average particle size of preferably 500 nm or less, more preferably 100 nm or less. When the average particle size is 500 nm or less, the printing original plate obtained has good water-based developability.

The toluene gel fraction of (b) the hydrophilic copolymer is preferably 60% to 99%. (b) When the toluene gel fraction of the hydrophilic copolymer is 60% or more, the resulting printing plate tends to have a practically sufficient strength.
When the (b) hydrophilic copolymer has a toluene gel fraction of 99% or less, the hydrophilic copolymer (b) and the thermoplastic elastomer (a) tend to be well mixed.
Here, the toluene gel fraction is obtained by dropping an appropriate amount of about 30% by mass dispersion of the (b) hydrophilic copolymer on a Teflon (registered trademark) sheet and drying at 130° C. for 30 minutes ( b) Take 0.5 g of a hydrophilic copolymer, immerse it in 30 mL of toluene at 25° C., shake it with a shaker for 3 hours, filter it with a 320 SUS mesh, and remove the non-passage at 130° C. for 1 hour. It refers to the mass fraction (%) obtained by dividing the mass after drying by 0.5 (g).

The content of the (b) hydrophilic copolymer in the photosensitive resin composition layer is 100% of the total amount of the photosensitive resin composition from the viewpoint of developability during printing plate preparation when developing in an aqueous developer. When expressed as % by mass, it is preferably 10% by mass to 70% by mass. (b) The content of the hydrophilic copolymer is more preferably 15% by mass to 60% by mass, more preferably 20% by mass to 50% by mass.

<(c) Photopolymerizable Monomer>
Examples of the photopolymerizable monomer (c) include, but are not limited to, esters of acids such as acrylic acid, methacrylic acid, fumaric acid and maleic acid; derivatives of acrylamide and methacrylamide; allyl esters; styrene and its derivatives; N-substituted maleimide compounds, and the like.

Examples of the photopolymerizable monomer (c) include, but are not limited to, diacrylates and dimethacrylates of alkanediols such as 1,6-hexanediol and 1,9-nonanediol; Diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, butylene glycol, diacrylate and dimethacrylate of dicyclopentadienyl; trimethylolpropane tri(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, isobornyl (meth)acrylate ) acrylates, phenoxypolyethylene glycol (meth)acrylate, pentaerythritol tetra(meth)acrylate, N,N'-hexamethylenebisacrylamide and methacrylamide, styrene, vinyl toluene, divinylbenzene, diacryl phthalate, triallyl cyanurate, Diethyl Fumarate, Dibutyl Fumarate, Dioctyl Fumarate, Distearyl Fumarate, Butyl Octyl Fumarate, Diphenyl Fumarate, Dibenzyl Fumarate, Dibutyl Maleate, Dioctyl Maleate, Fumaric Acid Bis(3-phenylpropyl) ester, dilauryl fumarate, dibehenyl fumarate, N-laurylmaleimide and the like can be mentioned.
These may be used individually by 1 type, and may be used in combination of 2 or more types.

From the viewpoint of even higher chipping resistance of the projections of the printing plate, the photosensitive resin composition contains 2.0% by mass or more of a monomer having 2 mol of a methacrylate group per 1 mol of the monomer as the photopolymerizable monomer (c). preferably.

The content of the (c) photopolymerizable monomer in the photosensitive resin composition layer is 1 mass when the total amount of the photosensitive resin composition is 100% by mass, from the viewpoint of obtaining a high-definition printed matter having a highlight region. % to 25 mass %. (c) The content of the photopolymerizable monomer is more preferably 5% by mass to 20% by mass, and even more preferably 8% by mass to 15% by mass.

<(d) Photoinitiator>
(d) The photopolymerization initiator is a compound that absorbs light energy and generates radicals, and various known ones can be used, and various organic carbonyl compounds and particularly aromatic carbonyl compounds are preferable. is.

(d) Examples of photopolymerization initiators include, but are not limited to, benzophenone, 4,4-bis(diethylamino)benzophenone, t-butylanthraquinone, 2-ethylanthraquinone, and 2,4-diethylthioxanthone. , isopropylthioxanthone, and 2,4-dichlorothioxanthone; Acetophenones such as hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone; Benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl Acylphosphine oxides such as pentylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; methylbenzoyl formate; 1,7-bisacridinylheptane; 9-phenylacridine; di-t-butyl-p-cresol; and the like.
These may be used individually by 1 type, and may be used in combination of 2 or more types.

The content of the (d) photopolymerization initiator in the photosensitive resin composition layer is the content of the photosensitive resin composition from the viewpoint of improving the plate formability during plate making and from the viewpoint of obtaining high-definition printed matter printing having a highlight region. When the total amount is 100% by mass, it is preferably 0.1% by mass to 10.0% by mass. (d) The content of the photopolymerization initiator is more preferably 1.0% by mass to 8.0% by mass, even more preferably 1.5% by mass to 5.0% by mass.

As the photopolymerization initiator (d), a decaying photopolymerization initiator and a hydrogen abstraction photopolymerization initiator may be used in combination. Since the image reproducibility and abrasion resistance of the printing plate are high, the amount 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. preferable.

(Infrared ablation layer)
The flexographic printing original plate of this embodiment has an infrared ablation layer on the photosensitive resin composition layer.
The infrared ablation layer can be processed with infrared rays, and serves as a mask image when the photosensitive resin composition layer is exposed and cured. When the unexposed portion of the photosensitive resin composition layer is washed out after the exposure is completed, the infrared ablation layer is also removed at the same time.

The infrared ablation layer comprises at least an infrared absorbing agent having a function of blocking radiation in the visible region from the ultraviolet region, absorbing light in the infrared region and converting it into heat, and dispersing the infrared absorbing agent in the system. It contains an assisting dispersant and a binder polymer.
In addition, optional components other than these, such as fillers, silicone oils, surfactants, and coating aids, can be contained within a range that does not impair the effects of the present invention.

The thickness of the infrared ablation layer of the flexographic printing original plate of the present embodiment is preferably thick from the viewpoint of ensuring the light shielding property against ultraviolet rays during the step of exposing the flexographic printing original plate, and the ablation property is increased. From the point of view, the thinner the better.
From the above viewpoints, the thickness of the infrared ablation layer is preferably 0.1 μm or more and 20 μm or less, more preferably 0.5 μm or more and 15 μm or less, and even more preferably 1.0 μm or more and 10 μm or less.

As for the non-infrared shielding effect of the infrared ablation layer, the optical density of the infrared ablation layer is preferably 2 or more, more preferably 3 or more. The optical density can be measured using a D200-II transmission densitometer (manufactured by GretagMacbeth). Further, the optical density is a so-called visual sensitivity (ISO visual), and the light to be measured has a wavelength range of about 400 to 750 nm.

<Infrared absorber>
The infrared ablation layer used in this embodiment preferably contains an infrared absorber.
As the infrared absorbing agent, a single substance or a compound having strong absorption characteristics in the wavelength range of 750 nm to 20,000 nm is usually used. It is preferable that the infrared absorbing agent also serves as a non-infrared shielding substance, but the infrared absorbing agent and the non-infrared shielding substance may be added separately.
As the infrared absorbing agent, those having high absorption in the infrared region and capable of uniformly dispersing in the infrared ablation layer are preferred. Such substances include, but are not limited to, inorganic pigments such as carbon black, graphite, iron oxide, chromium oxide, copper chromite, phthalocyanine and substituted phthalocyanine derivatives, cyanine dyes, merocyanine Pigments such as dyes, polymethine dyes and metal thiolate dyes can be used.
Materials that reflect or absorb ultraviolet light can be used as non-infrared shielding materials. Suitable examples include, but are not limited to, carbon black, ultraviolet absorbers, and graphite.
Both the infrared absorbing agent and the non-infrared shielding substance may be used singly or in combination of two or more.

As the infrared absorber, carbon black, which has a non-infrared shielding effect and is readily available and inexpensive, is particularly preferable.
The particle size of carbon black can be selected within an arbitrary range, but generally, the smaller the particle size, the higher the sensitivity to infrared rays and the worse the dispersibility. From the above viewpoints, the particle size of carbon black is preferably 20 nm or more and 80 nm or less, more preferably 25 nm or more and 70 nm or less, and even more preferably 30 nm or more and 60 nm or less.
Carbon black is not limited to the following, but is classified into, for example, furnace black, channel black, thermal black, acetylene black, lamp black, etc., depending on the production method. Furnace black is available and diverse. is preferable from the viewpoint of

The content of the infrared absorbing agent in the infrared ablative layer is preferably selected and added within a range that ensures sensitivity capable of being removed by the laser beam used during drawing processing of the infrared ablative layer.
The sensitivity to a laser beam increases as the amount of the infrared absorbing agent uniformly dispersed in the infrared ablation layer increases. From such a viewpoint, the content of the infrared absorbing agent in the entire infrared ablation layer is preferably 10% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 80% by mass or less, and 30% by mass or more and 70% by mass or less. is more preferred.

A method for forming an infrared ablative layer using carbon black as an infrared absorber will be described with an example.
A binder polymer solution is prepared using a suitable solvent, carbon black and a dispersant are added thereto, the carbon black is dispersed in the binder polymer solution, and then coated on a cover film such as a polyester film. A method of laminating or press-bonding a film to the photosensitive resin composition layer and transferring a non-infrared shielding layer that can be cut with an infrared laser is effective.
As a method for dispersing carbon black in the binder polymer solution, it is effective to combine forced stirring with a stirring blade and stirring using ultrasonic waves or various mills. Alternatively, a method of pre-kneading the binder polymer, carbon black and dispersant using an extruder or kneader and then dissolving the mixture in a solvent is also effective for obtaining good dispersibility of carbon black. Alternatively, carbon black may be force-dispersed in the polymer in the form of a latex solution.
The infrared absorbing agent preferably has a surface functional group capable of interacting with the adsorption portion of the dispersant, which will be described later. Examples of such surface functional groups include, but are not limited to, carbonyl groups, carboxyl groups, aldehyde groups, hydroxyl groups, phenyl groups, sulfone groups, nitro groups, maleic anhydride, quinones, lactones, esters, etc.
As a simple evaluation method for the surface functional group content of the infrared absorbent, the pH value determined by the measurement method specified in ASTM D 1512 is used.
In order to obtain sufficient interaction with the dispersant, the pH value is preferably 9 or less, more preferably 8.5 or less, and even more preferably 8 or less.
On the other hand, from the viewpoint of suppressing interaction between the infrared ablation layer and the cover film and facilitating peeling, the pH value is preferably 2.5 or higher, more preferably 3.0 or higher, and further preferably, 3.5 or more.

<Dispersant>
The dispersant contained in the infrared ablation layer is a compound having an adsorption portion capable of interacting with the surface functional group of the infrared absorbent and a resin-compatible portion compatible with the binder polymer.
The adsorption part of the dispersant is not limited to the following, but examples thereof include an amino group, an amide group, a urethane group, a carboxyl group, a carbonyl group, a sulfone group and a nitro group. Urethane groups are preferred.
Examples of the resin compatible part include, but are not limited to, saturated alkyls, unsaturated alkyls, polyethers, polyesters, poly(meth)acryls, and polyols.

<Binder polymer>
The infrared ablative layer preferably contains a binder polymer.
Examples of binder polymers include, but are not limited to, acrylic resins, styrene resins, vinyl chloride resins, vinylidene chloride resins, polyolefin resins, polyamide resins, polyacetal resins, and polybutadiene resins. , polycarbonate resins, polyester resins, polyphenylene sulfide resins, polysulfone resins, polyetherketone resins, polyimide resins, fluorine resins, silicone resins, urethane resins, urea resins, melamine resins, guanamine resins Examples include resins, epoxy resins, phenolic resins, and copolymers of these resins.

The binder polymer contains various functional groups such as an amino group, a nitro group, a sulfonic acid group, a phosphoric acid group, a carboxylic acid group, and a halogen within a range that does not impair compatibility with an infrared absorber such as carbon black and a dispersant. may contain

The binder polymer may be used singly or in combination of two or more.
When two or more types are used in combination, they may be selected according to the required performance.
For example, from the viewpoint of scratch resistance, thermoplastic elastomers composed of copolymers of monovinyl-substituted aromatic hydrocarbon monomers and conjugated diene monomers, hydrogenated products of the above copolymers, polyamide resins, and polyvinyl alcohol resins. Preferred are thermoplastic elastomers composed of copolymers of monovinyl-substituted aromatic hydrocarbon monomers and conjugated diene monomers, and more preferred are hydrogenated products of the above copolymers.
In addition, since the adhesion between the infrared ablation layer and the cover film is caused by the intermolecular force between the components contained in the infrared ablation layer and the components contained in the cover film, it is preferable to use a binder polymer with few polar groups from the viewpoint of peelability. preferred from For example, it is preferable to use a thermoplastic elastomer composed of a copolymer of a monovinyl-substituted aromatic hydrocarbon monomer and a conjugated diene monomer, a hydrogenated product of the copolymer, and poly(meth)acrylate.
Polyamide, polybutyral, polyvinyl alcohol, poly(meth)acrylate, and modified or partially saponified products thereof are preferably used when water developability is required.

The number average molecular weight of the binder polymer can be arbitrarily set, and may be selected in consideration of the desired PH (pinhole) resistance and ablation efficiency of the infrared ablation layer.
In general, the smaller the number average molecular weight, the softer and lower the scratch resistance, and conversely, the larger the number average molecular weight, the worse the abrasion efficiency.
From the viewpoint of the PH resistance of the infrared ablation layer, the number average molecular weight of the binder polymer is preferably 1,000 or more, more preferably 3,000 or more.
In consideration of abrasion efficiency, the number average molecular weight of the binder polymer is preferably 200,000 or less, more preferably 150,000 or less.
Upper and lower limits of these numerical values can be combined arbitrarily.
The number average molecular weight of the binder polymer can be controlled within the above numerical range by appropriately adjusting the polymerization conditions of the polymer, for example, the amount of monomer, polymerization time, polymerization temperature and the like.
It is also effective to obtain a desired number average molecular weight by mixing a plurality of polymers.

The content ratio of the binder polymer to the entire infrared ablative layer can be arbitrarily set within a range that does not impair the object of the present invention.
From the viewpoint of PH resistance, the content of the binder polymer in the entire infrared ablation layer is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. preferable.
On the other hand, from the viewpoint of improving the concentration of an infrared absorbent such as carbon black in order to improve the sensitivity to infrared rays, it is preferably 90% by mass or less, more preferably 70% by mass or less, and 60% by mass. More preferably: Upper and lower limits of these numerical values can be combined arbitrarily.

<Additive>
As will be described later, the infrared ablation layer is formed, for example, on a cover film, and in forming a film, it is generally applied in the form of a solution or dispersion onto the cover film and dried. preferable.
In order to improve the wettability of the solution or dispersion to the cover film and the uniformity of the film, a silicone resin, a surfactant, and other desired additives may be added.
Common nonionic, cationic, anionic, and amphoteric surfactants can be used as surfactants, and may be selected as appropriate.
Examples of silicone resins include, but are not limited to, non-modified silicone oils such as dimethyl silicone oil and methylphenyl silicone oil; polyether-modified silicones, aralkyl-modified silicones, fluoroalkyl-modified silicones, long-chain alkyl Modified silicone oils such as modified silicone can be used.
Examples of fluorine-based surfactants include, but are not limited to, perfluoroalkyl group-containing acid salts, perfluoroalkyl group-containing esters, fluorine-containing group-containing oligomers, and the like.
Of these, silicone resins are more preferable from an environmental point of view considering the gas generated during ablation, and polyether-modified silicones are particularly preferable from the viewpoint of the balance between releasability and coating stability of the coating liquid for producing the ablation layer. .
The content of surfactants and additives in the infrared ablative layer can be arbitrarily set within a range that does not impair the effects of the present invention.
As a range in which these surfactants and additives preferably exert their effects, the content of the surfactants and additives in the infrared ablative layer is preferably 0.1% by mass or more and 30% by mass or less. 5% by mass or more and 25% by mass or less is more preferable, and 1.0% by mass or more and 20% by mass or less is even more preferable.
These surfactants and additives may be either water-soluble or water-insoluble as long as they do not significantly increase the hygroscopicity of the infrared ablative layer, but from the viewpoint of hygroscopicity, water-insoluble ones are more preferred. .

<Coating solvent>
Solvents such as solutions and dispersions for forming the infrared ablative layer can be appropriately selected in consideration of the solubility of the polymer and infrared absorbing agent used.
A single solvent may be used alone, or a mixture of two or more solvents may be used.
Further, for example, it is effective to improve the film quality of the infrared ablation layer by mixing a solvent with a relatively low boiling point and a solvent with a high boiling point and controlling the volatilization speed of the solvent.
Solvents for forming the infrared ablation layer include, but are not limited to, toluene, xylene, cyclohexane, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, amyl acetate, methyl ethyl ketone, acetone, Cyclohexanone, ethylene glycol, propylene glycol, ethanol, water, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, dimethylacetamide, dimethylformamide, n-propyl alcohol, i-propyl alcohol, 1,4-dioxane, tetrahydrofuran, diethyl ether, Examples include n-hexane, n-heptane, n-pentane, acetonitrile and analogues thereof.

(cover film)
The cover film for forming the infrared ablative layer of the present embodiment is preferably a film having excellent dimensional stability, such as a polyethylene terephthalate film.
The cover film may be used in an untreated state, but may be used after being provided with functions such as release treatment and antistatic treatment, if necessary.

(middle layer)
The flexographic printing original plate of the present embodiment may further have one or more intermediate layers between the photosensitive resin composition layer and the infrared ablation layer.
In order to produce a high-definition printed matter having a highlight area, it is necessary to form minute dots having a flat portion at the tip of the dot with a diameter of 10 to 20 μm and a relief depth of 100 μm or more. In order to achieve such fine dots, the intermediate layer is preferably an oxygen-blocking layer having oxygen-blocking ability.
Also, the intermediate layer may be an adhesive layer having an adhesive function.
When the photosensitive resin composition layer is cured by irradiation with ultraviolet rays, the curing proceeds by radical polymerization. If oxygen coexists during polymerization, the radical-generating compound reacts with oxygen to suppress the polymerization reaction. When the polymerization reaction is suppressed and unreacted portions remain in the photosensitive resin composition layer, the finally formed pattern has a curved portion at the tip. On the other hand, when the coexisting amount of oxygen is reduced during UV curing, the polymerization reaction is less likely to be suppressed, and the finally formed pattern has a flat portion at the tip. Therefore, when a pattern having a flat portion at the tip is to be produced, it is effective to reduce the amount of oxygen in contact with the photosensitive resin composition layer by having the intermediate layer have oxygen blocking ability.

The intermediate layer also has the function of protecting the infrared ablation layer.
In the conventional flexographic printing plate manufacturing process, when the infrared ablation layer is transported as a film, it comes into contact with the roll and is physically damaged by rubbing against the protective film due to tight winding during transport of the film roll. and PH may occur.
Further, when the photosensitive resin composition layer and the infrared ablative layer are laminated by a method of coating the photosensitive resin composition layer on the infrared ablative layer while extruding, the heat-melted photosensitive resin composition is PH may occur due to the friction that occurs when flowing over the infrared ablation layer.
In order to prevent such generation of PH in the infrared ablation layer, the intermediate layer used in the flexographic printing original plate of the present embodiment preferably has physical strength and heat resistance.
As described above, in order to produce a high-definition printed matter having a highlight area, it is preferable to form fine dots having a flat portion at the tip of the dot with a diameter of 10 to 20 μm. Therefore, if the infrared ablation layer has a pH of 20 μm or more and a mask image for forming fine dots overlaps around it, dot formation failure will occur, resulting in a high-definition flexographic printing plate having a highlight region. There is a risk that it will not be possible to produce

Further, it is preferable that the intermediate layer can be washed with the same washing liquid as that for the infrared ablative layer and/or the photosensitive resin composition layer, from the viewpoint of simplicity of the manufacturing process of the flexographic printing plate.
If the intermediate layer is highly washable, the time required for the washing process can be shortened, the workability is improved, and the photosensitive resin composition layer positioned below the intermediate layer can be easily developed.

Materials suitably used for the intermediate layer include, but are not limited to, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinylpyrrolidone, polyvinyl chloride, polyvinyl chloride, Vinylidene, polyvinyl fluoride, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyacetal, polycarbonate, polystyrene, polycarbonate, polyethylene, polypropylene, cellulose derivatives, polyester, polyamide, polyimide, polyurethane, silicone rubber, butyl rubber, isoprene rubber, etc. polymers.
These polymers may be used individually by 1 type, and may be used in combination of 2 or more types.
Further, other components such as surfactants, antiblocking agents, release agents, UV absorbers, dyes and pigments may be added to the intermediate layer.
The thickness of the intermediate layer is preferably 0.5 μm or more and 20 μm or less. When the thickness of the intermediate layer is 0.5 μm or more, sufficient film strength can be obtained, and when it is 20 μm or less, sufficient washability can be obtained. The thickness of the intermediate layer is more preferably 0.5 μm or more and 10 μm or less, further preferably 0.5 μm or more and 5 μm or less.

Water-dispersible latex is also a suitable material for the intermediate layer.
Examples of water-dispersible latex include, but are not limited to, polybutadiene latex, natural rubber latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, polyvinylidene chloride latex, and polychloroprene latex. , polyisoprene latex, polyurethane latex, methyl methacrylate-butadiene copolymer latex, vinylpyridine polymer latex, butyl polymer latex, thiocol polymer latex, acrylate polymer latex and other water-dispersible latex polymers, and these polymers Examples include polymers obtained by copolymerizing other components such as acrylic acid and methacrylic acid.
Among these, a water-dispersible latex polymer containing a butadiene skeleton or an isoprene skeleton in the molecular chain is preferable from the viewpoint of hardness and rubber elasticity. Specifically, polybutadiene latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, and polyisoprene latex are preferred.
The water-dispersible latex contained in the intermediate layer used in the flexographic printing original plate of the present embodiment has a polar group, and the polar group includes a carboxyl group, an amino group, a hydroxyl group, a phosphate group, a sulfone Preferred examples include acid groups, salts thereof, and the like.

In the flexographic printing plate using the flexographic printing original plate of the present embodiment, the water-dispersible latex preferably has a carboxyl group or a hydroxyl group from the viewpoint of obtaining high washability and excellent adhesion between layers. .
These water-dispersible latexes containing polar groups may be used singly or in combination of two or more.

The water-dispersible latex having a carboxyl group is not particularly limited, but includes, for example, those containing an unsaturated monomer having a carboxyl group as a polymerization monomer. Examples of the unsaturated monomer having a carboxyl group include, but are not limited to, monobasic acid monomers and dibasic acid monomers.
Examples of monobasic acid monomers include, but are not limited to, acrylic acid, methacrylic acid, crotonic acid, vinyl benzoic acid, cinnamic acid, and sodium salts, potassium salts, and ammonium salts of these monobasic acid monomers. etc.
Dibasic acid monomers are not particularly limited, but examples include itaconic acid, fumaric acid, maleic acid, citraconic acid, muconic acid, and sodium salts, potassium salts, and ammonium salts of these dibasic acid monomers. is mentioned.
In the present embodiment, one type of unsaturated monomer having a carboxyl group may be used alone, or a plurality of types of unsaturated monomers having a carboxyl group may be used simultaneously.

Examples of the water-dispersible latex having a hydroxyl group include, but are not particularly limited to, ethylene-based monocarboxylic acid alkyl ester monomers. Examples of the ethylene-based monocarboxylic acid alkyl ester monomer include, but are not limited to, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, Hydroxypropyl, 1-hydroxypropyl acrylate, 1-hydroxypropyl methacrylate, hydroxycyclohexyl (meth)acrylate and the like.

From the viewpoint of resin adhesion, the content of the water-dispersible latex in the intermediate layer is preferably 3% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, relative to the total amount of the intermediate layer.
In addition, the content of the water-dispersible latex in the intermediate layer is preferably 90% by mass or less, more preferably 80% by mass or less, and 70% by mass or less from the viewpoint of suppressing stickiness. is more preferred.
When the content of the water-dispersible latex in the intermediate layer is 3% by mass or more, sufficient adhesion is obtained, and when the content is 90% by mass or less, sufficient film strength is obtained, A flexographic printing original plate with less tack can be obtained.

The toluene gel fraction of the water-dispersible latex is preferably 70% by mass or more and 90% by mass or less. It is more preferably 70% by mass or more and 85% by mass or less, and still more preferably 70% by mass or more and 80% by mass or less.
When the toluene gel fraction of the water-dispersible latex is in the range of 70% by mass or more and 90% by mass or less, a flexographic printing original plate with little stickiness can be obtained while maintaining sufficient rubber elasticity and film strength.

Here, the toluene gel fraction of water-dispersible latex can be measured by the following method.
0.5 g of the film obtained by drying the dispersion after emulsion polymerization of the water-dispersible latex at 130° C. for 30 minutes was immersed in 30 mL of toluene at 25° C., shaken for 3 hours using a shaker, and then dried to 320 SUS. After filtering through a mesh and drying the non-passing portion at 130° C. for 1 hour, the mass X (g) is measured.
The toluene gel fraction of water-dispersible latex is calculated from the following formula.
Toluene gel fraction (% by mass) of water-dispersible latex = X (g) / 0.5 (g) x 100
The toluene gel fraction of the water-dispersible latex can be controlled within the above numerical range by adjusting the polymerization temperature, monomer composition, amount of chain transfer agent, and particle size.

The water-soluble polyurethane contained in the intermediate layer is not particularly limited as long as it is a polymer having a urethane bond, and examples thereof include polyurethane obtained by reacting a polyol compound and a polyisocyanate.
In order to stably dissolve or disperse the water-soluble polyurethane in an organic solvent and/or water, it is also preferable to add a hydrophilic group-containing compound as a polymerization component in addition to the polyol compound and polyisocyanate.

Examples of the polyol compound include, but are not limited to, polyether polyol, polyester polyol, polycarbonate diol, and polyacryl polyol.
These may be used individually by 1 type, and may be used in combination of 2 or more types.
Among these, polyether polyol is preferable from the viewpoint of adhesion.
The polyether polyol is not particularly limited, but for example, a polyether polyol obtained by ring-opening copolymerization of a polyhydric alcohol with an ionically polymerizable cyclic compound, that is, a reaction product of a polyhydric alcohol and an ionically polymerizable cyclic compound. are mentioned.

Examples of the polyhydric alcohol include, but are not limited to, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, and polydecamethylene glycol. , glycerin, trimethylolpropane, pentaerythritol, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, hydroquinone, naphthohydroquinone, anthrahydroquinone, 1,4-cyclohexanediol, tricyclodecanediol, tricyclodecanediol Examples include methanol, pentacyclopentadecanediol, and pentacyclopentadecanedimethanol.
These may be used individually by 1 type, and may be used in combination of 2 or more types.

Examples of the ionically polymerizable cyclic compound include, but are not limited to, ethylene oxide, propylene oxide, 1,2-butylene oxide, butene-1-oxide, isobutene oxide, and 3,3-bischloromethyloxetane. , tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, dioxane, trioxane, tetraoxane, cyclohexene oxide, styrene oxide, epichlorohydrin, glycidyl methacrylate, allyl glycidyl ether, allyl glycidyl carbonate, butadiene monoxide, isoprene monoxide, vinyl oxetane, vinyl Cyclic ethers such as tetrahydrofuran, vinylcyclohexene oxide, phenylglycidyl ether, butylglycidyl ether, and benzoic acid glycidyl ester can be mentioned.
These may be used individually by 1 type, and may be used in combination of 2 or more types.

As the polyol compound, ring-opening copolymerization of the ionically polymerizable cyclic compound and cyclic imines such as ethyleneimine, cyclic lactone acids such as β-propiolactone and glycolic acid lactide, or dimethylcyclopolysiloxanes is performed. It is also possible to use polyether polyols.
The ring-opening copolymers of these ionically polymerizable cyclic compounds may be randomly bonded or may be bonded in blocks.

As the polyisocyanate, any polyisocyanate that is commonly used in the production of polyurethane can be used without particular limitation.
Examples of polyisocyanates include, but are not limited to, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1 , 5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 3,3′-dimethylphenylene diisocyanate, 4, 4′-biphenylene diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate, methylene bis(4-cyclohexyl isocyanate), 2,2,4-trimethylhexamethylene diisocyanate, bis(2-isocyanatoethyl) fumarate, 6-isopropyl-1, 3-phenyl diisocyanate, 4-diphenylpropane diisocyanate, lysine diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, tetramethyl xylylene diisocyanate, 2,5 (or 6)-bis(isocyanatomethyl)-bicyclo[2.2 .1] heptane and the like.
These polyisocyanates may be used alone or in combination of two or more.

The water-soluble polyurethane contained in the intermediate layer increases the PH resistance of the infrared ablation layer constituting the flexographic printing original plate when performing thermal extrusion molding in the manufacturing process of the flexographic printing original plate of the present embodiment, and increases the flexibility of the flexographic printing original plate. In order to maintain the properties, the elongation of the film made of the water-soluble polyurethane is preferably 300% or more, more preferably 600% or more.

Further, the heat softening temperature of the water-soluble polyurethane is preferably 80°C to 210°C. From the viewpoint of PH resistance, the temperature is preferably 80° C. or higher, and from the viewpoint of adhesion, it is preferably 210° C. or lower.
Further, the heat softening temperature of the water-soluble polyurethane is more preferably 110°C to 180°C, more preferably 120°C to 170°C.
The heat softening temperature of the water-soluble polyurethane can be measured with a Koka-type flow tester.
Further, the heat softening temperature of the water-soluble polyurethane can be controlled within the above numerical range by adjusting the type and combination of the diol component and the diisocyanate component that constitute the water-soluble polyurethane.
The properties that affect the PH resistance of the infrared ablation layer are considered to be the three parameters of the heat melting temperature, elongation and breaking strength of the water-soluble polyurethane film contained in the intermediate layer.
During the production of the flexographic printing original plate of the present embodiment, the temperature of the resin (the material of the photosensitive resin composition layer) after kneading is preferably about 120 to 140.degree. At that time, the closer or lower the heat softening temperature of the water-soluble polyurethane single film contained in the intermediate layer to the resin temperature after kneading, and the greater the elongation of the water-soluble polyurethane single film, the higher the temperature after kneading. In order to follow the shear stress of the resin, the infrared ablation layer and the intermediate layer can be easily formed into a sheet.
In addition, the breaking strength of the water-soluble polyurethane single film is measured by thermal lamination of the kneaded resin (including gel-like substances that are not kneaded properly), which is the material constituting the photosensitive resin composition layer, and the infrared ablation layer and the intermediate layer. Occasionally, the intermediate layer in direct contact with the kneaded resin is broken by scratching by the gelled material, and PH is generated in the infrared ablation layer.

The number average molecular weight of the water-soluble polyurethane is preferably 1,000 to 200,000, more preferably 30,000 to 100,000, from the viewpoint of flexibility of the intermediate layer.

Further, the water-soluble polyurethane contained in the intermediate layer is preferably a polyether polyurethane obtained by reacting a polyether polyol and an isocyanate, from the viewpoint of adhesion to the infrared ablation layer and the photosensitive resin composition layer. Although such polyether polyurethane is not particularly limited, for example, Superflex 300 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Hydran WLS202 (manufactured by DIC Corporation) and the like are commercially available.

The water-soluble polyurethane preferably has a polyether, polyester, polycarbonate, or polyester ether structure in the molecule, more preferably polyether, polyester, or polycarbonate, and further has a polyether structure from the viewpoint of adhesiveness. is preferred.

Resin adhesion, that is, adhesion between the intermediate layer and the photosensitive resin composition layer is developed by the water-dispersible latex and water-soluble polyurethane contained in the intermediate layer.
Regarding the initial adhesion, the water-soluble polyurethane mainly contributes to the resin adhesion, and the lower the glass transition temperature of the water-soluble polyurethane, the easier it is to get wet with the photosensitive resin composition layer, so the resin adhesion is excellent. tends to be
Further, the anchoring effect of the water-dispersible latex contributes to the adhesion after the flexographic printing original plate is left for a long period of time.
When a styrene-butadiene-based resin is used in the photosensitive resin composition layer, the styrene-butadiene-based resin is easily compatible with the water-dispersible latex in the intermediate layer. is expressed, and resin adhesion is maintained even after long-term storage.

The content of the water-soluble polyurethane in the intermediate layer is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 40% by mass or more, relative to the total amount of the intermediate layer.
The content of the water-soluble polyurethane in the intermediate layer is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.
Sufficient PH resistance is obtained when the content of the water-soluble polyurethane in the total amount of the intermediate layer is 10% by mass or more, and the content of the water-soluble polyurethane in the total amount of the intermediate layer is 90% by mass or less. , sufficient adhesion can be obtained.

The water-soluble polyurethane preferably has a polar group from the viewpoint of washability and strength of the intermediate layer at high temperatures.
Examples of polar groups include, but are not limited to, polyether groups such as hydroxy groups, alkoxy groups, ethylene oxide groups, and propylene oxide groups; carbonyl groups, carboxyl groups, amino groups, urea groups, cyano groups, A sulfonic acid group, a phosphoric acid group, and the like can be mentioned.
Among these, water-soluble polyurethanes having carboxyl groups or hydroxyl groups are preferred.

The intermediate layer may further contain a water-soluble polyamide.
The water-soluble polyamide is not particularly limited as long as it is a polymer having a polyamide bond.
Conventionally known soluble synthetic polymer compounds can be used as the polymer having polyamide bonds. Specifically, although not particularly limited, for example, polyetheramide (see, for example, JP-A-55-79437), polyetheresteramide (see, for example, JP-A-58-113537) , Tertiary nitrogen-containing polyamide (for example, see JP-A-50-76055), ammonium salt-type tertiary nitrogen atom-containing polyamide (for example, see JP-A-53-36555), an amide bond Addition polymers of amide compounds and organic diisocyanate compounds having one or more (see, for example, JP-A-58-140737), addition polymers of diamines having no amide bond and organic diisocyanate compounds (eg, JP-A-4 -97154, etc.) and the like.
These water-soluble polyamides may be used singly or in combination of two or more.
In particular, a tertiary nitrogen atom-containing polyamide and an ammonium salt-type tertiary nitrogen atom-containing polyamide that can impart an appropriate hardness to the intermediate layer are preferably used.

The content of the water-soluble polyamide in the intermediate layer is 10 to 700 parts by weight, preferably 15 to 600 parts by weight, and 20 to 500 parts by weight, based on 100 parts by weight of the water-dispersible latex. It is even more preferable to have
When the content of the water-soluble polyamide is 10 parts by mass or more with respect to 100 parts by mass of the water-dispersible latex, the film strength of the intermediate layer can be maintained, and sufficient PH resistance can be obtained.
Moreover, resin adhesiveness can be maintained by the content rate of water-soluble polyamide being 700 mass parts or less.

[Method for producing laminate for forming infrared ablation layer]
The infrared ablative layer-forming laminate for forming the infrared ablative layer used in the flexographic printing original plate of the present embodiment is not particularly limited, but can be produced, for example, as follows.
First, a coating liquid containing each component and solvent constituting the infrared ablative layer is prepared.
Next, the coating solution is applied onto the cover film to form a coating layer (coating step).
Next, the solvent is removed from the coating layer (drying step).
In the case of forming the intermediate layer described above, a coating liquid containing each component constituting the intermediate layer and a solvent is used on the infrared ablation layer side, and the same coating step as in the formation of the infrared ablation layer described above is performed. An intermediate layer is formed by passing through a drying process.

[Method for producing flexographic printing original plate]
The method for producing a flexographic printing original plate of the present embodiment includes at least a step of laminating a support, a photosensitive resin composition layer, and an infrared ablation layer in this order to obtain a laminate, and The composition layer has a shape having a surface on the side of the support, a surface on the side of the infrared ablation layer, and four side surfaces. and C. curing the sides. The flexographic printing original plate obtained by curing at least one side surface of the photosensitive resin composition layer in this manner exhibits an effect of suppressing lateral deformation when pressure is applied.

Further, in the method for producing a flexographic printing original plate according to the present embodiment, in the step of curing the side surface, it is preferable that the distance from the surface of the side surface to the cured portion in the layer-inward direction is 1 mm or more and 20 mm or less. In the flexographic printing original plate obtained by the production method of this embodiment, the distance of the cured portion of at least one side surface of the photosensitive resin composition layer is within a specific range, so that the side surface when pressure is applied There is a tendency for the deformation suppressing effect to manifest further.

In the method for producing a flexographic printing original plate of the present embodiment, as a specific example of the step of curing the side surface, for example, as shown in FIG. A step of curing at least one side surface, and a step of curing at least one side surface of the photosensitive resin composition layer by performing ultraviolet irradiation 5 from the side surface side of the photosensitive resin composition as shown in FIG. .

As described above, the ultraviolet irradiation method for curing the support-side surface and side surface of the photosensitive resin composition layer is not particularly limited. A method in which a light source is installed on the ablation layer side and irradiated with ultraviolet rays from the infrared ablation layer side, and a method in which a light source is installed on the side surface side of the photosensitive resin composition layer and ultraviolet rays are irradiated from the side surface side of the photosensitive resin composition layer. Another is a method in which a light source having an irradiation area equal to or greater than the area of the support is installed on the support side and ultraviolet rays are irradiated from the support side.
Among the above ultraviolet irradiation methods, when ultraviolet rays are irradiated from the support side, the side surface of the photosensitive resin composition layer is cured, and in addition, a uniform cured layer is formed on the support side surface of the photosensitive resin composition layer. be. In the method of irradiating ultraviolet light from the infrared ablation layer side and the method of irradiating ultraviolet light from the side surface side of the photosensitive resin composition layer, only the side surface irradiated with ultraviolet light can be cured in a limited manner.

In the method for producing a flexographic printing original plate of the present embodiment, light having a wavelength of 340 nm or more is applied to the side surface of the photosensitive resin composition layer as a light source for curing at least one side surface of the photosensitive resin composition layer of the laminate. It is preferable to install a light source that emits In the flexographic printing original plate obtained by such a production method, the side surface of the photosensitive resin composition layer is cured, so that the effect of suppressing side surface deformation when pressure is applied tends to be exhibited even more.

The light source is not particularly limited, but for example, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, zirconium lamps, carbon arc lamps, ultraviolet fluorescent lamps, UV-LEDs and the like can be used.

[Method for producing flexographic printing plate]
The method for producing a flexographic printing plate of the present embodiment includes, for example, the steps of irradiating the flexographic printing original plate obtained by the above-described method with ultraviolet rays from the support side, and irradiating the infrared ablation layer with infrared rays to draw a pattern. A process of processing, a process of irradiating the photosensitive resin composition layer with ultraviolet rays for pattern exposure, and a process of removing the infrared ablation layer and the unexposed photosensitive resin composition layer.
Thereafter, a step of post-exposure treatment is performed as necessary to obtain a flexographic printing plate (letterpress printing plate) from a cured product of the photosensitive resin composition layer.
From the viewpoint of imparting releasability, the surface of the flexographic printing plate may be brought into contact with a liquid containing a silicone compound and/or a fluorine compound.

In the step of irradiating ultraviolet rays from the support side, a conventional irradiation unit can be used.
As ultraviolet rays, ultraviolet rays with a wavelength of 150 to 500 nm can be used, and ultraviolet rays with a wavelength of 340 to 400 nm can be preferably used.
Although the light source is not particularly limited, for example, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, zirconium lamps, carbon arc lamps, ultraviolet fluorescent lamps, and the like can be used.
The step of irradiating with ultraviolet rays may be performed before the step of drawing a pattern on the infrared ablation layer, or may be performed after the step of drawing a pattern. A higher-definition relief image can be obtained by carrying out simultaneously with the step of irradiating ultraviolet rays from the side.
When the original flexographic printing plate has a cover film, the cover film is first peeled off.
Thereafter, the infrared ablation layer is pattern-irradiated with infrared rays to form a mask on the photosensitive resin composition layer.
Suitable infrared lasers include, for example, ND/YAG lasers (eg 1064 nm) or diode lasers (eg 830 nm).
Suitable laser systems for CTP platemaking technology are commercially available, and for example, a diode laser system CDI Spark (ESKO GRAPHICS) can be used, although not particularly limited.
The laser system includes a rotating cylindrical drum that holds a flexographic printing master, an IR laser irradiation device, and a layout computer, and image information is transmitted directly from the layout computer to the laser device.
As described above, after the pattern is drawn, the entire surface of the photosensitive resin composition layer is irradiated with ultraviolet rays through a mask.
This can be done with the plate mounted on the laser cylinder, but generally the plate is removed from the laser system and irradiated using a conventional irradiation unit.
As the irradiation unit, the same unit as that used for ultraviolet irradiation from the support side can be used.
If the flexographic printing original plate of the present embodiment has an intermediate layer such as an oxygen-inhibiting layer or an adhesive layer, and the intermediate layer as the oxygen-inhibiting layer absorbs a large amount of ultraviolet light and cannot be ignored in the pattern exposure step, the oxygen-inhibiting layer It is preferable to appropriately adjust the amount of ultraviolet irradiation in consideration of the amount of ultraviolet rays absorbed by the intermediate layer as the intermediate layer.

Next, a development process is performed.
A conventionally known method can be applied to the developing step.
Specifically, the flexographic printing original plate is exposed as described above, and then the unexposed portion is washed off with a solvent for solvent development or a washing solution for water development, or the unexposed portion heated to 40°C to 200°C. can be brought into contact with a predetermined absorbing layer capable of absorbing, and the unexposed portions can be removed by removing the absorbing layer.
After that, a flexographic printing plate is produced by post-exposure treatment if necessary.
If an intermediate layer comprising an adhesive layer or an oxygen inhibiting layer is provided between the infrared ablation layer and the photosensitive resin composition layer, it is preferably removed simultaneously in the development step.

The developing solvent used for solvent development of the unexposed area is not limited to the following, but examples include esters such as heptyl acetate and 3-methoxybutyl acetate; petroleum fractions, toluene, decalin and the like. hydrocarbons; and mixtures of alcohols such as propanol, butanol, and pentanol with chlorinated organic solvents such as tetrachlorethylene. The unexposed areas are washed out by jetting from a nozzle or by brushing with a brush.

As a washing liquid for water development, an alkaline aqueous solution or a neutral detergent can be used.
A surfactant can be preferably used in the washing liquid for water development.
Examples of surfactants include, but are not particularly limited to, anionic surfactants, amphoteric surfactants, and nonionic surfactants. These may be used individually by 1 type, and may be used in mixture of 2 or more types.
Examples of anionic surfactants include, but are not limited to, sulfates, higher alcohol sulfates, higher alkyl ether sulfates, sulfated olefins, alkylbenzenesulfonates, and α-olefinsulfonic acids. salts, phosphate ester salts, dithiophosphate ester salts, and the like.
Examples of amphoteric surfactants include, but are not limited to, amino acid-type amphoteric surfactants, betaine-type amphoteric surfactants, and the like.
Examples of nonionic surfactants include, but are not limited to, higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene oxide adducts, higher Polyethylene glycol surfactants such as alkylamine ethylene oxide adducts, fatty acid amide ethylene oxide adducts, polypropylene glycol ethylene oxide adducts, glycerol fatty acid esters, pentaerythritol fatty acid esters, sorbitol and sorbitan fatty acid esters, and polyhydric alcohols. Examples include polyhydric alcohol surfactants such as alkyl esters and fatty acid amides of alkanolamines.

Moreover, the alkaline aqueous solution contains a pH adjuster.
The pH adjuster may be either an organic material or an inorganic material, but is preferably one that can adjust the pH to 9 or higher. Examples of pH adjusters include, but are not limited to, sodium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, sodium metasilicate, and sodium succinate.

Absorbent layers for thermal development include, but are not limited to, nonwoven materials, paper stocks, fibrous fabrics, open-cell foams, and porous materials.
Preferred absorbent layers are nonwoven materials of nylon, polyester, polypropylene, polyethylene, and combinations of these nonwoven materials. A particularly preferred absorbent layer is a nonwoven continuous web of nylon or polyester.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these.

[Production Example 1]
(Synthesis of hydrophilic copolymer)
125 parts by mass of water and (α-sulfo(1-nonylphenoxy)methyl-2-(2-propenyloxy)ethoxy-poly( 2 parts by mass of the ammonium salt of oxy-1,2-ethanediyl ("Adekari Soap" (manufactured by ADEKA) was initially charged, and the internal temperature was raised to 80° C. Next, 10 parts by mass of styrene and 60 parts by mass of butadiene were added. parts, 23 parts by weight of butyl acrylate, 5 parts by weight of methacrylic acid, and 2 parts by weight of acrylic acid, and 2 parts by weight of t-dodecyl mercaptan to prepare an oily mixture, and 28 parts by weight of water. parts, 1.2 parts by mass of sodium peroxodisulfate, 0.2 parts by mass of sodium hydroxide, and (α-sulfo(1-nonylphenoxy)methyl-2-(2-propenyloxy)ethoxy-poly(oxy-1 , 2-ethanediyl) was prepared, and the oily mixture was added to the pressure-resistant reaction vessel over 5 hours and the aqueous solution was added over 6 hours at a constant flow rate to carry out a polymerization reaction. rice field.
Then, in the pressure-resistant reaction vessel, the temperature was maintained at 80° C. for 1 hour to complete the polymerization reaction, obtain a copolymer latex, and then cool.
Furthermore, after adjusting the pH of the produced copolymer latex to 7 with sodium hydroxide, unreacted monomers are removed by a steam stripping method, filtered through a 200-mesh wire mesh, and finally filtered. An aqueous dispersion of a hydrophilic copolymer was obtained by adjusting the solid content concentration of the liquid to 40% by mass.
The resulting aqueous dispersion of the hydrophilic copolymer was dried in a vacuum dryer at 50° C. to remove water and obtain a hydrophilic copolymer.

[Production Example 2]
(Preparation of base film (support))
As a solution for the adhesive layer coated on the support (base film), 55 parts by mass of Tufprene 912 (manufactured by Asahi Kasei Corporation, trade name), which is a block copolymer of styrene and 1,3-butadiene, and paraffin oil. (average carbon number 33, average molecular weight 470, density at 15 ° C. 0.868) 38 parts by mass, 1,9-nonanediol diacrylate 2.5 parts by mass, 2,2-dimethoxy-phenylacetophenone 1.5 parts Parts by mass, 3 parts by mass of epoxy ester 3000M (manufactured by Kyoeisha Chemical Co., Ltd., trade name), and 1.5 parts by mass of Varifast Yellow 3150 (manufactured by Orient Chemical Industry, trade name) are dissolved in toluene and solidified. A 25% solution was obtained.
After that, the obtained solution is applied to one side of a 188 μm thick polyester film using a knife coater so that the ultraviolet transmittance (UV transmittance) is 4%, and dried at 70° C. for 1 minute to form an adhesive layer. A support (base film) having
The UV transmittance of the support is measured using an ultraviolet exposure machine AFP-1500 (manufactured by Asahi Kasei Co., Ltd., trade name), and a UV illuminance meter MO-2 type machine (manufactured by ORC Manufacturing, trade name, UV-35 filter). was measured and calculated.

[Production Example 3]
(Preparation of laminate for infrared ablation layer formation)
100 parts by mass of carbon black (CB) as an infrared absorber, 20 parts by mass of Solsperse 39000 (manufactured by Nippon Lubrizol Co., Ltd., trade name, base value 30 mgKOH/g) as a dispersant, and a styrene-butadiene-styrene copolymer elastomer as a binder polymer. 80 parts by mass of Tuftec H1051 (manufactured by Asahi Kasei Co., Ltd., trade name), which is a hydrogenated product of , and 600 parts by mass of toluene were mixed to obtain an infrared ablation layer coating solution.
This infrared ablation layer coating solution was coated on a PET film having a thickness of 100 μm as a cover film so that the film thickness after drying was 3 μm, and dried at 90° C. for 2 minutes, followed by infrared ablation. A laminate for forming an infrared ablative layer, which is a laminate of the layer and the cover film, was obtained.

[Example 1]
(Preparation of flexographic printing original plate)
32 parts by mass of the hydrophilic copolymer obtained in [Production Example 1] above and 28 parts by mass of a styrene-butadiene-styrene copolymer [D-KX405: manufactured by Kraton] were mixed at 140°C using a pressure kneader. After mixing with, liquid polybutadiene [LBR-352: manufactured by Kuraray] 32 parts by weight, 1,9-nonanediol diacrylate 8 parts by weight, 1,6-hexanediol dimethacrylate 5 parts by weight, 2,2-dimethoxyphenylacetophenone 2 Part by mass, 1 part by mass of 2,6-di-t-butyl-p-cresol, and 1 part by mass of carbinol-modified silicone oil [KF-6000: manufactured by Shin-Etsu Chemical Co., Ltd.] were added little by little over 15 minutes, After finishing the addition, the mixture was further kneaded for 20 minutes to obtain a photosensitive resin composition 1.
Next, the obtained photosensitive resin composition 1 is put into an extrusion molding machine, and the photosensitive resin composition layer 1 obtained in [Production Example 2] is applied to one side of the photosensitive resin composition layer 1 extruded from the T-shaped die. A base film (support) is laminated, and a release film (Diafoil MRV100, manufactured by Mitsubishi Chemical Corporation) is laminated on the surface of the photosensitive resin composition layer 1 opposite to the support lamination side, and a photosensitive resin A laminate of the support and the photosensitive resin composition layer 1 was obtained such that the composition layer 1 had a thickness of 1.0 mm.
Next, the release film is peeled off, and the laminate for forming an infrared ablative layer obtained in [Production Example 3] is laminated so that the infrared ablative layer is in contact with the photosensitive resin composition layer 1. , the photosensitive resin composition layer 1, and the infrared ablation layer were laminated in this order to obtain a laminate. The photosensitive resin composition layer in the obtained laminate had a shape having a surface on the side of the support, a surface on the side of the infrared ablation layer, and four side surfaces.
Next, a high-pressure mercury lamp (manufactured by PHILIPS, Actinic BL TL-K 40W/10-R) is installed on the side surface of the laminate (the side surface of the photosensitive resin composition layer), and the photosensitive resin of the laminate is The surface of the composition layer on the side of the support and one of the four side surfaces to be chucked were irradiated with ultraviolet rays (wavelength: 370 nm) so that the exposure amount was 700 mJ (illuminance meter: UV-M03A manufactured by Orc Manufacturing Co., Ltd., light receiving Device: UV-35 manufactured by ORC Mfg. Co., Ltd. A flexographic printing original plate was obtained by curing the surface of the photosensitive resin composition layer on the support side and the chucking side out of the four side surfaces. Table 1 shows the manufacturing conditions for each of the flexographic printing original plates.
A part of the side surface of the flexographic printing original plate irradiated with ultraviolet rays is cut out, the cover sheet of the infrared ablation layer is peeled off, and the infrared ablation layer is wiped off with a cloth impregnated with ethanol to remove it, exposing the photosensitive resin composition layer. It was in a state to FTIR was used to measure the position of the exposed photosensitive resin composition layer 1 mm in the layer inner direction from the side irradiated with ultraviolet rays, and it was 800 to 820 cm ^-1 due to the vinyl group of the photopolymerizable monomer. It was confirmed that the UV-irradiated side surface was cured, because the peak absorbance of 2 was less than half of that before UV irradiation.
[Criteria for determining curing]
○ (cured): the absorbance peak value at 800 to 820 cm ^-1 is less than half that before UV irradiation × (uncured): the absorbance peak value at 800 to 820 cm ^-1 is more than half before UV irradiation In the composition layer, the distance from the surface of the cured side surface to the cured portion in the inner direction of the layer was 1 mm.
In this example, the distance of the cured portion was determined by measuring points at intervals of 1 mm from the side of the photosensitive resin composition layer irradiated with ultraviolet rays toward the inside of the layer. Among the measurement points at which the resulting absorbance peak value of 800 to 820 cm ^-1 is less than half of that before ultraviolet irradiation, the measurement point with the longest distance from the side irradiated with ultraviolet rays and the distance from the side is defined as the curing distance. It was found by stipulating.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
After peeling off the cover sheet of the infrared ablation layer of the flexographic printing original plate and drawing a dot image (AM 150 line, data 1% to 98% halftone dot) on the infrared ablation layer using a laser lithography machine (CDI) manufactured by ESKO. , ESKO's UV-LED exposure machine (XPS Crystal 4835) under atmospheric conditions, as shown in Table 1, the exposure amount from the support side (back exposure amount) is 1700 mJ, the exposure amount from the mask side (relief exposure UV irradiation was carried out simultaneously from both the support side and the mask side so that the dose) was 9100 mJ.
After exposure, an aqueous solution (aqueous developer) of 1% polyoxyalkylene alkyl ether (Newcol 2308: manufactured by Nippon Nyukazai Co., Ltd.) and 1% potassium carbonate was prepared, and was heated at 40° C. using 220 W (trade name, Asahi Kasei Co., Ltd.). was washed (developed) with , and the unexposed area was removed.
After drying at 50° C. for 10 minutes, the plate was post-exposed with an ultraviolet germicidal lamp and an ultraviolet chemical lamp to obtain a flexographic printing plate in order to remove the tackiness of the surface. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 2]
A high-pressure mercury lamp was placed on the side surface (the side surface of the photosensitive resin composition layer) of the laminate (laminate of support, photosensitive resin composition layer 1, and infrared ablation layer) obtained in [Example 1]. Installed, ultraviolet rays (wavelength: 370 nm) are irradiated to the side surface to be chucked out of the surface on the support side and the four side surfaces of the photosensitive resin composition layer so that the exposure amount is 700 mJ, and the side other than the side to be chucked is irradiated. Three sides (non-chucking sides) were irradiated with ultraviolet rays (wavelength: 370 nm) at an exposure amount of 500 mJ to obtain a flexographic printing original plate in which four sides of the photosensitive resin composition layer were cured. . By the same method as in Example 1, it was confirmed that the UV-irradiated side surface of the obtained flexographic printing original plate was cured. In the photosensitive resin composition layer, the distance from the surface of the cured side surface to the cured portion in the direction toward the inside of the layer was 1 mm for both the chucking side surface and the non-chucking side surface.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
A flexographic printing plate was obtained under the same conditions as in [Example 1] except that the obtained flexographic printing original plate was used. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 3]
A high-pressure mercury lamp was placed on the side surface (the side surface of the photosensitive resin composition layer) of the laminate (laminate of the support, the photosensitive resin composition layer 1, and the infrared ablation layer) obtained in [Example 1]. Installed, ultraviolet rays (wavelength: 370 nm) are irradiated so that the exposure amount is 1,000 mJ on the side surface to be chucked among the surface on the support side and the four side surfaces of the photosensitive resin composition layer, and the side surface to be chucked. was cured to obtain a flexographic printing original plate. By the same method as in Example 1, it was confirmed that the UV-irradiated side surface of the obtained flexographic printing original plate was cured. In the photosensitive resin composition layer, the distance from the cured side surface to the cured portion in the direction inside the layer was 1 mm.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
A flexographic printing plate was obtained under the same conditions as in [Example 1] except that the obtained flexographic printing original plate was used. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 4]
A high-pressure mercury lamp was placed on the side surface (the side surface of the photosensitive resin composition layer) of the laminate (laminate of support, photosensitive resin composition layer 1, and infrared ablation layer) obtained in [Example 1]. Installed, ultraviolet rays (wavelength: 370 nm) are irradiated so that the exposure amount is 1,000 mJ on the side surface to be chucked among the surface on the support side and the four side surfaces of the photosensitive resin composition layer, and the side surface to be chucked. The other three sides were irradiated with ultraviolet rays (wavelength: 370 nm) so that the exposure amount was 500 mJ, to obtain a flexographic printing original plate in which the four sides of the photosensitive resin composition layer were cured. By the same method as in Example 1, it was confirmed that the UV-irradiated side surface of the obtained flexographic printing original plate was cured. In the photosensitive resin composition layer, the distance from the surface of the cured side surface to the cured portion in the direction toward the inside of the layer was 1 mm for both the chucking side surface and the non-chucking side surface.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
A flexographic printing plate was obtained under the same conditions as in [Example 1] except that the obtained flexographic printing original plate was used. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 5]
The support side (support side of the photosensitive resin composition layer) of the laminate (laminate of the support, the photosensitive resin composition layer 1, and the infrared ablation layer) obtained in [Example 1] was irradiated with ultraviolet rays. High-pressure mercury lamps are placed side by side at intervals of 1 cm so that the area is larger than the area of the support, and ultraviolet rays (wavelength: 370 nm) are irradiated so that the exposure amount of the support surface is 690 mJ, thereby supporting the photosensitive resin composition layer. A flexographic printing original plate cured on the body side and four sides was obtained. By the same method as in Example 1, it was confirmed that the UV-irradiated support side surface and four side surfaces of the obtained flexographic printing original plate were cured. In the photosensitive resin composition layer, the distance from the cured side surface to the cured portion in the direction inside the layer was 1 mm. In the photosensitive resin composition layer, the distance from the surface of the cured support side to the cured portion in the layer inner direction was 0.3 mm.
In this example, the distance of the cured portion on the support side was measured as follows. After peeling off the cover sheet on the side of the infrared ablation layer and wiping off the infrared ablation layer with a cloth impregnated with ethanol to expose the photosensitive resin composition layer, the exposed photosensitive resin composition layer is removed. Measurements were taken using FTIR with the surface as the first measurement point. When the peak value of absorbance at 800 to 820 cm ⁻¹ in the measurement result is more than half of that before ultraviolet irradiation, the photosensitive resin composition layer is polished by 0.1 mm with an abrasive in the layer inner direction, and FTIR is performed again. Measurement was performed using The above polishing and FTIR measurement are repeated, and the distance from the surface of the photosensitive resin composition layer to the surface of the support at which the absorbance peak value of 800 to 820 cm ^-1 is less than half of that before UV irradiation is measured with a thickness gauge. By subtracting the thickness of the support from this, the distance of the cured portion on the support side was obtained.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
Using the obtained flexographic printing original plate, after drawing on the infrared ablation layer of [Example 1], exposure from the support side was not performed, and ultraviolet irradiation was performed only from the mask side so that the exposure amount was 9100 mJ. gone. A flexographic printing plate was obtained under the same conditions as in [Example 1] except for the preparation of the flexographic printing plate. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 6]
UV-LED on the side surface side (side surface side of the photosensitive resin composition layer) of the laminate (laminate of support, photosensitive resin composition layer 1, and infrared ablation layer) obtained in [Example 1]. is installed, and among the support side surface and four side surfaces of the photosensitive resin composition layer, the side surface to be chucked is irradiated with ultraviolet light (wavelength: 360 nm) so that the exposure amount is 300 mJ, and other than the side surface to be chucked. UV rays (wavelength: 360 nm) were irradiated to the three sides of the photosensitive resin composition layer so that the exposure amount was 200 mJ to obtain a flexographic printing original plate in which the four sides of the photosensitive resin composition layer were cured. By the same method as in Example 1, it was confirmed that the UV-irradiated side surface of the obtained flexographic printing original plate was cured. In the photosensitive resin composition layer, the distance from the surface of the cured side surface to the cured portion in the direction toward the inside of the layer was 1 mm for both the chucking side surface and the non-chucking side surface.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
A flexographic printing plate was obtained under the same conditions as in [Example 1] except that the obtained flexographic printing original plate was used. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 7]
When producing the support having the adhesive layer described in [Production Example 2] above, a solution for the adhesive layer was applied to one side of a 125 μm polyester film so that the ultraviolet transmittance (UV transmittance) was 25%. did.
When obtaining the laminate of [Example 1], the laminate (support, photosensitive resin composition layer 1, and infrared ablation layer laminated so that the thickness of the photosensitive resin composition layer is 1.5 mm) body).
A high-pressure mercury lamp is installed on the side surface side (the side surface side of the photosensitive resin composition layer) of the laminate (laminate of the support, the photosensitive resin composition layer 1, and the infrared ablation layer), and the photosensitive resin composition layer is UV light (wavelength: (370) nm) is applied to the side surface to be chucked so that the exposure amount is 700 mJ, and the three side surfaces other than the side surface to be chucked are exposed. UV rays (wavelength: (370) nm) were irradiated in an amount of 500 mJ to obtain a flexographic printing original plate in which four sides of the photosensitive resin composition layer were cured. By the same method as in Example 1, it was confirmed that the UV-irradiated side surface of the obtained flexographic printing original plate was cured. In the photosensitive resin composition layer, the distance from the surface of the cured side surface to the cured portion in the direction toward the inside of the layer was 1 mm for both the chucking side surface and the non-chucking side surface.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
After drawing on the infrared ablation layer of [Example 1] using the obtained flexographic printing original plate, ultraviolet irradiation was performed so that the exposure amount of the support surface was 2100 mJ and the exposure amount of the mask surface was 10600 mJ. A flexographic printing plate was obtained under the same conditions as in [Example 1] except for the preparation of the flexographic printing plate. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 8]
A high-pressure mercury lamp was installed on the side surface side (side surface side of the photosensitive resin composition layer) of the laminate (laminate of the support, the photosensitive resin composition layer 1, and the infrared ablation layer) of [Example 7], Of the support-side surface and four side surfaces of the photosensitive resin composition layer, the side surface to be chucked was irradiated with ultraviolet rays (wavelength: 370 nm) at an exposure amount of 700 mJ, and the three side surfaces other than the side surface to be chucked were irradiated. was irradiated with ultraviolet rays (wavelength: 370 nm) so that the exposure amount was 700 mJ to obtain a flexographic printing original plate in which four sides of the photosensitive resin composition layer were cured. By the same method as in Example 1, it was confirmed that the UV-irradiated side surface of the obtained flexographic printing original plate was cured. In the photosensitive resin composition layer, the distance from the cured side surface to the cured portion in the direction inside the layer was 1 mm.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
A flexographic printing plate was obtained under the same conditions as in [Example 7] except that the obtained flexographic printing original plate was used. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 9]
A high-pressure mercury lamp was installed on the side surface side (side surface side of the photosensitive resin composition layer) of the laminate (laminate of the support, the photosensitive resin composition layer 1, and the infrared ablation layer) of [Example 7], Of the support-side surface and four side surfaces of the photosensitive resin composition layer, the side surface to be chucked was irradiated with ultraviolet rays (wavelength: 370 nm) so that the exposure amount was 1,000 mJ, and the other three surfaces than the side surface to be chucked. One side was irradiated with ultraviolet rays (wavelength: 370 nm) so that the exposure amount was 500 mJ, to obtain a flexographic printing original plate in which four sides were cured. By the same method as in Example 1, it was confirmed that the UV-irradiated side surface of the obtained flexographic printing original plate was cured. In the photosensitive resin composition layer, the distance from the surface of the cured side surface to the cured portion in the inner direction of the layer was 2 mm on the chucking side surface and 1 mm on the non-chucking side surface.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
A flexographic printing plate was obtained under the same conditions as in [Example 7] except that the obtained flexographic printing original plate was used. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 10]
A high-pressure mercury lamp was installed on the side surface side (side surface side of the photosensitive resin composition layer) of the laminate (laminate of the support, the photosensitive resin composition layer 1, and the infrared ablation layer) of [Example 7], Of the support-side surface and four side surfaces of the photosensitive resin composition layer, the side surface to be chucked was irradiated with ultraviolet rays (wavelength: 370 nm) so that the exposure amount was 1,000 mJ, and the other three surfaces than the side surface to be chucked. One side was irradiated with ultraviolet rays (wavelength: 370 nm) so that the exposure amount was 700 mJ to obtain a flexographic printing original plate in which four sides of the photosensitive resin composition layer were cured. By the same method as in Example 1, it was confirmed that the UV-irradiated side surface of the obtained flexographic printing original plate was cured. In the photosensitive resin composition layer, the distance from the surface of the cured side surface to the cured portion in the inner direction of the layer was 2 mm on the chucking side surface and 1 mm on the non-chucking side surface.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
A flexographic printing plate was obtained under the same conditions as in [Example 7] except that the obtained flexographic printing original plate was used. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 11]
The support side (support side of the photosensitive resin composition layer) of the laminate (laminate of the support, the photosensitive resin composition layer 1, and the infrared ablation layer) obtained in [Example 7] was irradiated with ultraviolet rays. High-pressure mercury lamps were placed side by side at intervals of 1 cm so that the area was larger than the area of the support, and ultraviolet rays were irradiated so that the exposure amount of the support surface was 390 mJ. A flexographic printing plate precursor cured on one side was obtained. By the same method as in Example 1, it was confirmed that the UV-irradiated support side surface and four side surfaces of the obtained flexographic printing original plate were cured. In the photosensitive resin composition layer, the distance from the cured side surface to the cured portion in the direction inside the layer was 1 mm. In the photosensitive resin composition layer, the distance from the surface of the cured support side to the cured portion in the layer inner direction was 0.7 mm.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
Using the obtained flexographic printing original plate, after drawing on the infrared ablation layer of [Example 7], exposure from the support side was not performed, and ultraviolet irradiation was performed only from the mask side so that the exposure amount was 10600 mJ. gone. A flexographic printing plate was obtained in the same manner as in [Example 7] except for the conditions for preparing the flexographic printing plate. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 12]
UV-LED on the side surface side (side surface side of the photosensitive resin composition layer) of the laminate (laminate of support, photosensitive resin composition layer 1, and infrared ablation layer) obtained in [Example 7]. is installed, and among the support side surface and four side surfaces of the photosensitive resin composition layer, the side surface to be chucked is irradiated with ultraviolet light (wavelength: 360 nm) so that the exposure amount is 300 mJ, and other than the side surface to be chucked. UV rays (wavelength: 360 nm) were irradiated to the three sides of the photosensitive resin composition layer so that the exposure amount was 200 mJ to obtain a flexographic printing original plate in which the four sides of the photosensitive resin composition layer were cured. By the same method as in Example 1, it was confirmed that the UV-irradiated side surface of the obtained flexographic printing original plate was cured. In the photosensitive resin composition layer, the distance from the surface of the cured side surface to the cured portion in the direction toward the inside of the layer was 1 mm for both the chucking side surface and the non-chucking side surface.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
A flexographic printing plate was obtained under the same conditions as in [Example 7] except that the obtained flexographic printing original plate was used. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 13]
In the production of the photosensitive resin composition, 60 parts by mass of a styrene-butadiene-styrene copolymer [D-KX405: manufactured by Kraton] was mixed at 180 ° C. using a pressure kneader, and then liquid polybutadiene [LBR-352: Kuraray 32 parts by mass, 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, 2,6-di-t-butyl A liquid mixture of 1 part by mass of p-cresol and 1 part by mass of amino-modified silicone oil [KF-8000: manufactured by Shin-Etsu Chemical Co., Ltd.] was added little by little over 15 minutes, and kneaded for another 20 minutes after the addition was completed to form a photosensitive resin composition. Got item 2.
A laminate was obtained by laminating the support, the photosensitive resin composition layer 2 and the infrared ablation layer in this order so that the thickness of the photosensitive resin composition layer 2 was 1.5 mm.
A high-pressure mercury lamp is installed on the side surface of the laminate (the side surface of the photosensitive resin composition layer), and the surface of the photosensitive resin composition layer on the side of the support and among the four side surfaces, the side surface to be chucked has an exposure amount. UV light (wavelength: 370 nm) is irradiated to 300 mJ, and UV light (wavelength: 370 nm) is irradiated to 3 sides other than the side to be chucked so that the exposure amount is 200 mJ. A flexographic printing master was obtained which was cured on four sides in the layer. By the same method as in Example 1, it was confirmed that the UV-irradiated side surface of the obtained flexographic printing original plate was cured. In the photosensitive resin composition layer, the distance from the surface of the cured side surface to the cured portion in the direction toward the inside of the layer was 1 mm for both the chucking side surface and the non-chucking side surface.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
After drawing on the infrared ablation layer of the flexographic printing original plate, ultraviolet irradiation was carried out so that the exposure amount on the support surface was 4100 mJ and the exposure amount on the mask surface was 12700 mJ. Next, using 3-methoxybutyl acetate as a developer, development is performed at a liquid temperature of 30° C. and a speed of 100 mm/min with an “AFP-1321P” developing machine (trade name, manufactured by Asahi Kasei Corporation), followed by drying at 60° C. for 2 hours. to obtain a flexographic printing plate. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Example 14]
When obtaining the laminate of [Example 13], the laminate (support, photosensitive resin composition layer 2, and infrared ablation layer) was adjusted so that the thickness of the photosensitive resin composition layer 2 was 2.5 mm. Laminate) was obtained.
A high-pressure mercury lamp is installed on the side surface side (side surface side of the photosensitive resin composition layer) of the laminate (laminate of the support, the photosensitive resin composition layer 2, and the infrared ablation layer), and the photosensitive resin composition layer is UV light (wavelength: 370 nm) is irradiated to the chucking side surface so that the exposure amount is 500 mJ, and the exposure amount is 300 mJ for the three side surfaces other than the chucking side surface. A flexographic printing original plate was obtained by irradiating ultraviolet rays (wavelength: 370 nm) so that four sides of the photosensitive resin composition layer were cured. By the same method as in Example 1, it was confirmed that the UV-irradiated side surface of the obtained flexographic printing original plate was cured. In the photosensitive resin composition layer, the distance from the surface of the cured side surface to the cured portion in the direction toward the inside of the layer was 1 mm for both the chucking side surface and the non-chucking side surface.
In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
After drawing on the infrared ablation layer of the flexographic printing original plate, ultraviolet irradiation was performed so that the exposure amount of the support surface was 3700 mJ and the exposure amount of the mask surface was 18,000 mJ. Other conditions for preparing a flexographic printing plate were the same as in [Example 13] to obtain a flexographic printing plate. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Comparative Example 1]
A flexographic printing original plate was obtained without irradiating all sides of the laminate (laminate of the support, the photosensitive resin composition layer 1, and the infrared ablation layer) of [Example 1] with ultraviolet rays. In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
Thereafter, a flexographic printing plate was obtained under the same conditions as in [Example 1] except that the obtained flexographic printing original plate was used. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Comparative Example 2]
A flexographic printing original plate was obtained without irradiating all side surfaces of the laminate (laminate of the support, the photosensitive resin composition layer 1, and the infrared ablation layer) of [Example 7] with ultraviolet rays. In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
Thereafter, a flexographic printing plate was obtained under the same conditions as in [Example 1] except that the obtained flexographic printing original plate was used. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Comparative Example 3]
A flexographic printing original plate was obtained without irradiating all sides of the laminate (laminate of support, photosensitive resin composition layer 2, and infrared ablation layer) of Example 13 with ultraviolet rays. In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
Thereafter, a flexographic printing plate was obtained under the same conditions as in [Example 1] except that the obtained flexographic printing original plate was used. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Comparative Example 4]
A flexographic printing original plate was obtained without irradiating all sides of the laminate (laminate of support, photosensitive resin composition layer 2, and infrared ablation layer) of Example 14 with ultraviolet rays. In addition, the degree of deformation of the obtained flexographic printing original plate was evaluated by the method described later. Table 2 shows the evaluation results.

(Preparation of flexographic printing plate)
Thereafter, a flexographic printing plate was obtained under the same conditions as in [Example 1] except that the obtained flexographic printing original plate was used. The halftone dot forming property of the obtained flexographic printing plate was evaluated by the method described later. Table 2 shows the evaluation results.

[Method for evaluating degree of deformation]
The flexographic printing original plate obtained by the above method is clamped to the drum roll of a laser ablation device CDI Crystal 4835 manufactured by ESKO, and after 30 minutes, the photosensitive resin composition on the chucking side and the non-chucking side of the flexographic printing original plate The deformation state of the side surface of the layer was confirmed and evaluated as follows.
〔Evaluation criteria〕
1: The magnitude of deformation on the side surface of the photosensitive resin composition layer was 1 mm or more in the direction perpendicular to the side surface.
2: The magnitude of deformation on the side surface of the photosensitive resin composition layer was less than 1 mm in the direction perpendicular to the side surface.
3: No deformation was observed on the side surface of the photosensitive resin composition layer.

[Evaluation Method for Halftone Dot Formability]
The halftone dot image of the flexographic printing plate obtained by the above method was checked for the minimum halftone dot formation at line AM 150, and the halftone dot formability was evaluated as follows. Here, the AM150 line of the halftone dot image refers to the division unit when dividing the image into a grid pattern. Specifically, the AM150 line is the division unit for dividing 1 inch into 150 halftone dots. , the minimum halftone dot is the minimum laser irradiation area for forming a dot, and can be calculated by the following formula.
Minimum halftone dot formation (%) = (minimum laser irradiation area for forming a dot in one halftone dot / area of entire halftone dot) x 100
〔Evaluation criteria〕
1: The minimum formed halftone dot of AM150 line was less than 3% of the data.
2: The minimum halftone dot formation for AM150 line was 3% or more and less than 5%.
3: The minimum formed halftone dot of the AM150 line was 5% or more of the data.
As shown in FIG. 10, the halftone dot formability is defined by irradiating the portion of the black mask enclosed by the dashed line with a laser beam, then exposing the uncured resin to UV light to obtain a cured resin, washing the resin, and forming dots. It is a property of how much the laser-irradiated area and the area of the top surface of the formed dots match when forming halftone dots arranged at regular intervals.

Reference Signs List 1: support, 2: cured portion on the side surface of the photosensitive resin composition layer, 2′: cured portion on the support side surface of the photosensitive resin composition layer, 3: uncured portion on the photosensitive resin composition layer, 4... Infrared ablation layer, 5... Ultraviolet irradiation

Claims (8)

A flexographic printing original plate comprising a laminate in which at least a support, a photosensitive resin composition layer, and an infrared ablation layer are laminated in this order,
The photosensitive resin composition layer of the laminate has a shape having a support side surface, an infrared ablation layer side surface, and four side surfaces, and in the photosensitive resin composition layer, among the four side surfaces, at least A flexographic printing master which is hardened on one side or hardened on at least one side and the side facing the support. The original flexographic printing plate according to claim 1, wherein at least two of the four sides of the photosensitive resin composition layer of the laminate are cured. The original flexographic printing plate according to claim 1 or 2, wherein all sides of the photosensitive resin composition layer of the laminate are cured. The flexo according to any one of claims 1 to 3, wherein the photosensitive resin composition layer of the laminate has a distance of 1 mm or more and 20 mm or less from the cured side surface to the cured portion in the layer inner direction. Original print. 2. In the photosensitive resin composition layer of the laminate, the cured surface is one or more side surfaces, and the distance from the surface of the side surface to the cured portion in the layer-inward direction is 1 mm or more and 20 mm or less. 5. The flexographic printing original plate according to any one of -4. a step of laminating at least a support, a photosensitive resin composition layer, and an infrared ablation layer in this order to obtain a laminate;
The photosensitive resin composition layer of the laminate has a shape having a support side surface, an infrared ablation layer side surface, and four side surfaces, and at least one side surface of the photosensitive resin composition layer has a wavelength of 340 nm or more. A method for producing a flexographic printing original plate, comprising the step of curing the side surface by irradiating with light of. 7. The method for producing a flexographic printing original plate according to claim 6, wherein in the step of curing the side surface, the distance from the surface of the side surface to the cured portion in the layer-inward direction is 1 mm or more and 20 mm or less. 8. A light source emitting light having a wavelength of 340 nm or more is installed on the side surface of the photosensitive resin composition layer as a light source for curing at least one side surface of the photosensitive resin composition layer of the laminate. A method for producing a flexographic printing original plate according to .

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