Photosensitive resin printing plate precursor and method for producing printing plate using the same

Abstract

To provide a photosensitive resin printing plate precursor with reduced bleed-out from a photosensitive resin layer, which exhibits superior developability with a developer mainly composed of water.SOLUTION: A photosensitive resin printing plate precursor has a photosensitive resin layer on a support, the photosensitive resin layer containing at least (A) polyvinyl alcohol and / or a derivative thereof, (B) a compound having an ethylenic double bond, (C) a photopolymerization initiator, and (D) a surfactant having an alkyl group and a sulfo group or a salt thereof and being free of fluorine.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a photosensitive resin printing plate original and a method for manufacturing a printing plate using the same.

Background Art

[0002] As a method for forming a relief on a photosensitive resin printing plate original, a method is generally used in which ultraviolet rays are irradiated onto a photosensitive resin layer through an image mask or an original film to selectively cure the image portion, and the uncured portion is removed using a developing solution.

[0003] From the viewpoints of reducing environmental load and impact on the human body, and from the viewpoint of handleability, a developing solution mainly composed of water is preferably used, and a water-soluble polymer is preferably used in the photosensitive resin composition for forming the photosensitive resin layer. As the water-soluble polymer, polyvinyl alcohol and its derivatives are preferably used because they have high relief strength, excellent image reproducibility, and can suppress the adhesiveness of the relief surface. As such a photosensitive resin printing plate original, for example, (i) a modified partially saponified polyvinyl acetate having a functional group introduced into the side chain, (ii) a tertiary nitrogen atom-containing polyamide, (iii) a photopolymerizable unsaturated compound, and (iv) a convex printing plate original having a photosensitive resin layer formed using a photosensitive resin composition containing a photoinitiator (see, for example, Patent Document 1), and a printing plate original for dry offset printing having a photosensitive resin layer containing fluorine and partially saponified vinyl acetate on a support (see, for example, Patent Document 2) have been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Polyvinyl alcohol and its derivatives are crystalline polymers having a large number of hydroxyl groups. In the photosensitive resin layer containing polyvinyl alcohol and its derivatives, a crystal structure is formed by the interaction between hydroxyl groups. Therefore, in order to remove the photosensitive resin layer in the developing process, the developer needs to penetrate into the crystal structure, resulting in a problem that the time required for development becomes long. Further, such a crystal structure reduces the compatibility with a compound having an ethylenic double bond or the like, and causes bleed-out of a compound having an ethylenic double bond or the like from the photosensitive resin layer. For this reason, even in the printing plate original disclosed in Patent Documents 1 and 2, there are problems in bleed-out from the photosensitive resin layer and developability with a developer mainly composed of water.

[0006] In view of the above problems of the prior art, an object of the present invention is to provide a photosensitive resin printing plate original having less bleed-out from the photosensitive resin layer and excellent developability with a developer mainly composed of water.

Means for Solving the Problems

[0007] In order to achieve the above object, the present invention mainly has the following configurations. [1] A photosensitive resin printing plate original having a photosensitive resin layer on a support, wherein the photosensitive resin layer contains at least polyvinyl alcohol and / or its derivative (A), a compound (B) having an ethylenic double bond, a photopolymerization initiator (C), and a surfactant (D) having an alkyl group and a sulfo group or its salt and not containing fluorine. [2] The photosensitive resin printing plate original according to [1], wherein the surfactant (D) further has a polyoxyethylene group. [3] The photosensitive resin printing plate original according to [1] or [2], wherein the surfactant (D) further has an aromatic ring. [4] The photosensitive resin printing plate original according to any one of [1] to [3], wherein the surfactant (D) is contained in the photosensitive resin layer in an amount of 3 to 15% by mass. A method for manufacturing a printing plate, comprising: an exposure step of irradiating ultraviolet rays to a photosensitive resin layer of a photosensitive resin printing plate original according to any one of [5][1] to [4] to photocure an exposed portion of the photosensitive resin layer; and a development step of removing an uncured portion of the photosensitive resin layer with a developer mainly composed of water.

Effect of the Invention

[0008] The photosensitive resin printing plate original of the present invention has less bleed-out from the photosensitive resin layer and is excellent in developability with a developer mainly composed of water.

Embodiments for Carrying Out the Invention

[0009] The photosensitive resin printing plate original of the present invention (hereinafter, may be abbreviated as "printing plate original") has a photosensitive resin layer on a support. Here, the photosensitive resin layer refers to a layer containing at least polyvinyl alcohol and / or its derivative (A) described later, a compound (B) having an ethylenic double bond, a photopolymerization initiator (C), and a surfactant (D) having an alkyl group and a sulfo group or its salt and not containing fluorine. By having a photosensitive resin layer, for example, by irradiating ultraviolet rays in an image pattern, a desired relief can be formed on the support. The photosensitive resin layer may have two or more layers. The support has a function of holding the photosensitive resin layer and the relief. Further, if necessary, a cover film or a heat-sensitive mask layer may be provided on the photosensitive resin layer. By providing a cover film on the photosensitive resin layer, the surface of the photosensitive resin layer can be protected and the adhesion of foreign substances and the like can be suppressed. The photosensitive resin layer and the cover film may be in direct contact, or one or more layers such as an anti-adhesion layer may be provided between the photosensitive resin layer and the cover film.

[0010] Examples of the support include a plastic sheet made of polyester or the like, a synthetic rubber sheet made of styrene-butadiene rubber or the like, and a metal plate made of steel, stainless steel, aluminum or the like.

[0011] From the viewpoints of handleability and flexibility, the thickness of the support is preferably 100 to 350 μm.

[0012] The support is preferably subjected to an easy adhesion treatment, which can improve the adhesiveness with the photosensitive resin layer. Examples of the easy adhesion treatment method include mechanical treatments such as sandblasting, physical treatments such as corona discharge, and chemical treatments such as coating. Among these, from the viewpoint of adhesiveness, it is preferable to provide an easy adhesion layer by coating.

[0013] The photosensitive resin layer contains at least polyvinyl alcohol and / or its derivatives (A) (hereinafter may be abbreviated as "component (A)"), a compound (B) having an ethylenic double bond (hereinafter may be abbreviated as "component (B)"), a photopolymerization initiator (C) (hereinafter may be abbreviated as "component (C)"), and a surfactant (D) having an alkyl group and a sulfo group or its salt and not containing fluorine (hereinafter may be abbreviated as "component (D)"). When the photosensitive resin layer is irradiated with light, free radicals are generated from the (C) component in the photosensitive resin layer. The generated free radicals can undergo radical polymerization with the (B) component to form a relief with excellent image reproducibility for obtaining a desired printed image due to the crosslinked structure. Further, the (A) component has the effect of imparting structural strength to the photosensitive resin layer and the relief as a matrix thereof, and can improve the image reproducibility. As described above, by using the water-soluble (A) component, it can be developed with a developer mainly composed of water. However, the conventional photosensitive resin layer has a problem that the development rate is slow due to the crystal structure caused by the interaction between hydroxyl groups, and the (B) component and the like are likely to bleed out. Therefore, in the present invention, as the (D) component, among various surfactants, a surfactant having an alkyl group and a sulfo group or its salt and not containing fluorine is selected, so that the hydrophilic sulfo group or its salt interacts with the hydroxyl group of the (A) component, and the interaction between hydroxyl groups is suppressed by the alkyl group, thereby increasing the development rate and improving the developability. In addition to suppressing the interaction between hydroxyl groups, the compatibility between the (B) component and the like and the (A) component is improved by the alkyl group, so that the bleeding out of the (B) component can be suppressed. In the conventional photosensitive resin composition, the surfactant containing fluorine used had a tendency to reduce the compatibility with the (B) component and the like due to fluorine. However, in the present invention, by selecting a surfactant not containing fluorine, the compatibility between the (B) component and the (D) component is improved, so that the bleeding out of the (B) component and the (D) component can be suppressed.

[0014] Among the component (A) in the present invention, polyvinyl alcohol refers to the general term for (i) polyvinyl alcohol with a saponification degree of 100% consisting of vinyl alcohol structural units and (i) partially saponified polyvinyl alcohol having (i) vinyl alcohol structural units and (ii) vinyl acetate structural units. A polyvinyl alcohol derivative refers to one in which a functional group is introduced into these main chains and / or side chains, or one having another structural unit. By containing such a component (A), the relief strength can be increased and the image reproducibility can be improved. In addition, the adhesiveness of the relief surface can be suppressed.

[0015] The polyvinyl alcohol derivative preferably has (i) vinyl alcohol structural units, (ii) vinyl acetate structural units, and (iii) structural units represented by the following general formula (1) and / or structural units represented by the general formula (2). In the structural units represented by (iii) the following general formula (1) and / or the general formula (2), having an ethylenic double bond can further improve the image reproducibility. In addition, since the ethylenic double bond crosslinks upon exposure, the water resistance of the relief during development is improved, and brush scratches, cracks, and wear on the relief surface can be suppressed.

[0016]

Chemical formula

[0017] In general formulas (1) to (2), R 1 represents an alkylene group and / or a divalent organic group having a cyclic structure, and R 2 represents a hydrogen atom or a methyl group. R 1 preferably has a cyclic structure, and the bulky cyclic structure in the side chain of the component (A) secures the voids between the components (A) having high crystallinity, and the crystallinity can be further reduced. Thereby, the retention of the component (B) in the photosensitive resin layer in the photosensitive resin layer can be enhanced, and bleed-out can be further suppressed. In particular, R 1By having a cyclic structure at a position closer to the main chain than the ethylenic double bond of the side chain, i.e., at a position closer to the main chain, the effect of steric hindrance by the cyclic structure is enhanced compared to the case where the cyclic structure is at the end of the side chain, and bleed-out can be more effectively suppressed. Also, R 1 By having a cyclic structure at the position of, compared to the case where the cyclic structure is at the end of the side chain, the decrease in radical polymerizability of the ethylenic double bond of the side chain due to the steric hindrance of the cyclic structure is suppressed, and the image reproducibility can be further improved.

[0018] Examples of the divalent organic group having an alkylene group include, for example, -C p H 2p COO-C q H 2q -OCO-, -COO-C p H 2p -OCO-, -C p H 2p -OCO- and the like. Here, p and q each independently represent a natural number.

[0019] Examples of the cyclic structure include residues derived from, for example, alicyclic hydrocarbons, heterocyclic compounds, aromatic hydrocarbons, heteroaromatic compounds, etc. Examples of the alicyclic hydrocarbon include cyclohexane, cyclopentane, cyclobutane, cyclopropane, cyclopentadiene, decalin, adamantane, camphor, etc. Examples of the heterocyclic compound include 2-pyrrolidine, tetrahydrofuran, tetrahydrothiophene, pyran, thiopyran, pyrazole, imidazole, piperidine, morpholine, etc. Examples of the aromatic hydrocarbon or heteroaromatic compound include phenyl, benzyl, pyridine, naphthylene, pyrrole, furan, thiophene, pyrazole, benzimidazole, indole, isoquinoline, purine derivatives, pyrimidine, oxazole, thiazole, etc. Two or more of these may be present. Also, these may have substituents, and examples of the substituent include, for example, halogen group, hydroxy group, mercapto group, ether group, amino group, carboxylic acid group, ester group, urethane group, aldehyde group, nitro group, CF 3Examples thereof include a group, a cyano group, etc. Note that these residues may be monovalent groups or polyvalent groups depending on their bonding positions. For example, residues of cyclohexane include a cyclohexyl group, a cyclohexylene group, etc. Among these, residues of alicyclic hydrocarbons are preferred, which can reduce the SP value of the component (A), improve the compatibility in the photosensitive resin layer, and further suppress bleed-out. Among alicyclic hydrocarbons, cyclohexane is more preferred.

[0020] Examples of the divalent organic group having a cyclic structure include, for example, -C p H 2p COO-X-C q H 2q -OOC-, -X-COO-C p H 2p -OOC-, -X-C p H 2p -OOC-, etc. Here, X represents the divalent group of the aforementioned cyclic structure, and p and q each independently represent a natural number.

[0021] R in the general formulas (1) to (2) 2 represents a hydrogen atom or a methyl group. When a hydrogen atom is selected as R 2 , the photocrosslinking reaction rate is faster than that in the case of a methyl group, so the sensitivity of the photosensitive resin layer can be improved. Depending on the desired sensitivity, a hydrogen atom or a methyl group can be appropriately selected.

[0022] In component (A), (i) the content of the vinyl alcohol structural unit is preferably 55 to 85 mol% with respect to the total of (i) to (iii). By setting the content of (i) to 55 mol% or more, the developability with respect to a developer mainly composed of water can be further improved. On the other hand, by setting the content of (i) to 85 mol% or less, the compatibility with component (B) can be further improved. In addition, the water absorption of component (A) can be suppressed, and the warping of the printing plate can be suppressed. Further, (ii) the content of the vinyl acetate unit is preferably 10 to 40 mol% with respect to the total of (i) to (iii). By setting the content of (ii) within such a range, the water absorption of component (A) can be suppressed, and the warping of the printing plate can be suppressed. Further, (iii) the total content of the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) is preferably 0.1 to 10 mol% with respect to the total of (i) to (iii). By setting the content of (iii) to 0.1% or more, the image reproducibility and the water resistance of the relief can be further improved. The content of (iii) is preferably 0.5% or more. On the other hand, by setting the content of (iii) to 10 mol% or less, the developability with respect to a developer mainly composed of water can be further improved.

[0023] From the viewpoint of improving the printing durability of the printing plate, the weight average molecular weight of component (A) is preferably 10,000 or more. On the other hand, from the viewpoints of the processability of the photosensitive resin layer and suppressing the increase in the viscosity of the developer during development, the weight average molecular weight of component (A) is preferably 200,000 or less, and more preferably 100,000 or less. The weight average molecular weight of component (A) can be determined by GPC measurement. In the present invention, using a gel permeation chromatograph - multi-angle light scattering photometer manufactured by Wyatt Technology, the weight average molecular weight is measured under the conditions of a column temperature of 40 °C and a flow rate of 0.7 mL / min.

[0024] As a method for producing the polyvinyl alcohol derivative of component (A), for example, in the case of the polyvinyl alcohol derivative having the structural units of (i) to (iii) described above, (1) reacting a partially saponified polyvinyl alcohol with an acid anhydride to introduce a reactive group such as a carboxyl group into the polymer side chain starting from the hydroxyl group of the partially saponified polyvinyl alcohol, and reacting the reactive group with an unsaturated epoxy compound; (2) partially saponifying a copolymer of vinyl acetate and an unsaturated carboxylic acid, an unsaturated carboxylate and / or an unsaturated carboxylic acid ester, and reacting the carboxyl group of this polymer with an unsaturated epoxy compound; (3) reacting a carboxylic acid compound having an ethylenic double bond starting from the hydroxyl group of the partially saponified polyvinyl alcohol, etc. can be mentioned.

[0025] The content of component (A) in the photosensitive resin layer is preferably 25% by weight or more in terms of solid content, and the printing resistance can be improved. On the other hand, the content of component (A) in the photosensitive resin layer is preferably 70% by weight or less in terms of solid content, and the flexibility of the photosensitive resin layer can be improved. In addition, when two or more kinds of component (A) are contained, the content refers to the total content thereof.

[0026] In the present invention, component (B) refers to a compound having an ethylenic double bond and a molecular weight of less than 10,000. The molecular weight of component (B) is preferably 2,000 or less.

[0027] Examples of component (B) include (meth)acrylates described in International Publication No. 2017 / 038970, glycerol di(meth)acrylate, (meth)acrylic acid adducts of propylene glycol diglycidyl ether, tetrahydrofurfuryl (meth)acrylate, etc. Two or more of these may be contained. Here, (meth)acrylate is a general term for acrylate and methacrylate, and (meth)acrylic acid is a general term for acrylic acid and methacrylic acid. As component (B), a compound having a polar group such as a hydroxyl group, a carboxyl group, an amino group, a sulfo group or a heterocyclic ring is preferable because of its good compatibility with component (A).

[0028] The content of component (B) in the photosensitive resin layer is preferably 5 to 200 parts by mass with respect to 100 parts by mass of component (A).

[0029] As component (C), those having a function of generating radicals by self-decomposition or hydrogen abstraction by light absorption are preferably used. For example, benzoin alkyl ethers, benzophenones, anthraquinones, benzyls, acetophenones, diacetyls and the like can be mentioned. Two or more of these may be contained. In the present invention, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl-phenyl-ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-methylpropanone, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropane-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone and the like are preferably used.

[0030] The content of component (C) in the photosensitive resin layer is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of component (A).

[0031] Generally, a surfactant has a hydrophilic moiety and a lipophilic moiety in the molecule. The surfactant of component (D) in the present invention has a sulfo group or its salt as the hydrophilic moiety and an alkyl group as the lipophilic moiety. As described above, by selecting an alkyl group as the lipophilic moiety, in addition to suppressing the interaction between hydroxyl groups and improving the developability with respect to a developer mainly composed of water, the compatibility between component (A) and component (B) etc. can be improved, and bleed-out of component (B) can be suppressed. Note that when the lipophilic moiety contains fluorine, the compatibility between component (B) and component (D) tends to decrease due to fluorine, and there is a problem of bleed-out. Although increasing the amount of component (D) is effective for improving developability, when the amount of component (D) is increased, the problem of bleed-out becomes more prominent. In the present invention, by selecting a surfactant that does not contain fluorine, the compatibility between component (B) and component (D) is improved, so that bleed-out can be suppressed and developability can be improved.

[0032] Examples of component (D) include alkyl sulfates and their salts, polyoxyethylene alkyl ether sulfates and their salts, alkylbenzene sulfonic acids and their salts, dialkyl sulfosuccinic acids and their salts, sulfosuccinic acid alkyl monoamides and their salts, alkyl diphenyl ether disulfonic acids and their salts, aliphatic acid amide ether sulfates and their salts, fatty acid methyl taurates and their salts, etc. Examples of the salt include sodium salts, potassium salts, etc. Two or more of these may be contained.

[0033] Among these, those having a polyoxyethylene group or those having an aromatic ring are preferable. When component (D) has a polyoxyethylene group, the developability with respect to a developer mainly composed of water can be further improved. In addition, when component (D) has an aromatic ring, due to the bulky structure, the interaction between the hydroxyl groups of component (A) is further suppressed, and the compatibility with component (B) is further improved, so that the developability can be further improved and bleed-out of component (B) can be further suppressed.

[0034] The content of component (D) in the photosensitive resin layer is preferably 3% by mass or more in terms of solid content, which can further improve the developability with a developer mainly composed of water and more effectively suppress bleed-out. More preferably, the content of component (D) is 5% by mass or more. On the other hand, the content of component (D) is preferably 15% by mass or less in terms of solid content, which can improve the water resistance of the relief layer after development and further improve the image reproducibility. When two or more kinds of component (D) are contained, the total content thereof is meant. In addition, emulsifiers or surfactants obtained by diluting or dissolving the aforementioned component (D) in a solvent are commercially available. Even when these are used, the content of component (D) refers to the content of the aforementioned component (active ingredient), not the content of the emulsifier or surfactant including their solvents.

[0035] In addition to the components (A) to (D), the photosensitive resin composition of the present invention may contain a binder polymer, a compatibilizer, a polymerization inhibitor, a dye, a pigment, a surfactant other than component (D), an antifoaming agent, an ultraviolet absorber, a fragrance, etc., as necessary.

[0036] By containing a compatibilizer in the photosensitive resin layer, the compatibility of the components constituting the photosensitive resin layer can be enhanced, the bleed-out of free components can be more effectively suppressed, and the flexibility of the photosensitive resin layer can be improved. Examples of the compatibilizer include polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol and their derivatives. The content of the compatibilizer in the photosensitive resin layer is preferably 30% by mass or less.

[0037] By containing a polymerization inhibitor in the photosensitive resin layer, the thermal stability can be improved. Examples of the polymerization inhibitor include phenols, hydroquinones, catechols, hydroxyamine derivatives, etc. One or more of these may be contained. The content of the polymerization inhibitor in the photosensitive resin layer is preferably 0.001 to 5% by mass.

[0038] The thickness of the photosensitive resin layer is preferably 100 μm or more, which can ensure the height of the relief of the printing plate and suppress the so-called bottoming out phenomenon in which ink adheres to the support surface during printing, while the thickness of the photosensitive resin layer is preferably 2.0 mm or less, which can improve printing reproducibility.

[0039] Examples of the cover film include plastic sheets made of polyester, polyethylene, polypropylene, etc. The thickness of the cover film is preferably 10 to 150 μm from the viewpoint of handling and flexibility. The surface of the cover film may be roughened to improve adhesion to the original film. Examples of methods for roughening the surface include sandblasting, chemical etching, and coating with a coating agent containing matte particles.

[0040] In addition, when the printing plate precursor of the present invention is used in a so-called CTP plate making method in which laser irradiation is performed based on image data controlled by a digital device, an image mask is formed on the spot from the mask layer element, and exposed and developed, the printing plate precursor may further have a heat-sensitive mask layer. The heat-sensitive mask layer is preferably one that effectively blocks ultraviolet light, absorbs infrared laser light during drawing, and is instantly sublimated or ablated in part or in whole by the heat. This creates a difference in optical density between the laser irradiated part and the non-irradiated part, and can function similarly to a conventional original film. When the photosensitive resin printing plate precursor has a heat-sensitive mask layer, it may have an adhesion adjustment layer between the photosensitive resin layer and the heat-sensitive mask layer, and may have a peeling auxiliary layer between the heat-sensitive mask layer and the cover film.

[0041] Examples of the heat-sensitive mask layer, adhesion adjustment layer, and peeling auxiliary layer include those described in WO 2017 / 038970.

[0042] Next, the method for producing the photosensitive resin composition and the printing plate precursor will be described taking as an example a case in which a photosensitive resin layer and a cover film are provided on a support.

[0043] For example, the components (A) to (D) and other additives as necessary are added to a solvent, and the mixture is heated and dissolved with stirring to obtain a photosensitive resin composition solution for the photosensitive resin layer. Examples of the solvent include a water / alcohol mixed solvent.

[0044] A solution of the photosensitive resin composition is cast onto a support having an easy-adhesion layer as required, and dried to form a photosensitive resin layer. A cover film having an anti-tack layer as required is then adhered to the photosensitive resin layer to obtain a printing plate precursor.

[0045] Next, a method for producing a printing plate of the present invention will be described. The method for producing a printing plate of the present invention includes at least an exposure step of irradiating the photosensitive resin layer of the above-mentioned printing plate precursor of the present invention with ultraviolet light to photocure the exposed portion of the photosensitive resin layer, and a development step of removing the uncured portion of the photosensitive resin layer with a developer.

[0046] In the exposure step, a negative or positive original film is attached to the photosensitive resin layer from which a cover film (if any) is peeled off, and the exposed portion of the photosensitive resin layer is photocured by irradiating with ultraviolet light having a wavelength of 300 to 400 nm. For ultraviolet light irradiation, it is preferable to use, for example, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a carbon arc lamp, a chemical lamp, a UV-LED lamp, or the like.

[0047] In the developing step, it is preferable to dissolve the unexposed area using a spray type developing device or a brush type washing machine. The developer may be water and / or an organic solvent, and is preferably composed mainly of water.

[0048] Furthermore, if necessary, a post-exposure step of irradiating with ultraviolet light after development may be carried out, which makes it possible to further strengthen the relief by reaction of unreacted component (B) through the post-exposure step.

[0049] A printing plate produced using the printing plate precursor of the present invention can be used for letterpress printing using a flatbed press for label printing, a rotary press, an intermittent rotary press, etc., dry offset printing, flexographic printing, etc. Among these, it can be more suitably used for letterpress printing and dry offset printing. EXAMPLES

[0050] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Evaluation methods in the examples and comparative examples are described below.

[0051] (1) Bleed-out amount The cover film was peeled off from the printing plate precursor obtained in each Example and Comparative Example, and 32 samples of 8 cm x 8 cm were cut, and each sample was stored in a thermostatic chamber at a temperature of 40°C and a relative humidity of 80% for 7 days. The bleed-out components on the surface of each sample were wiped off with an oil blotting paper of 8 cm x 8 cm, and the weight change before and after wiping with the oil blotting paper was measured. The number average value was calculated and converted into the weight change per unit area (g / m2).

[0052] (2) Development speed The cover film was peeled off from the printing plate precursor obtained in each Example and Comparative Example. A negative film containing a solid image and a grayscale negative film for sensitivity measurement were vacuum-attached to the photosensitive resin layer, and exposed to light using a chemical lamp FL20SBL-360 20 watts under conditions that gave a grayscale sensitivity of 16±1 steps (main exposure). Then, using a brush-type developing device DX-A3 (manufactured by Takano Machinery Works, Ltd.), the plate was developed in water at 30° C. for 30 seconds and dried at 60° C. for 10 minutes to obtain a printing plate for evaluating the development speed.

[0053] The thickness difference between the solid image area and the adjacent non-image area was measured at 12 points selected at 1 cm intervals from the solid image area of ​​the printing plate for evaluating the development speed using a thickness gauge 547-401 (manufactured by Mitutoyo Corporation). The average value of the thickness difference at the 12 points was calculated as the development speed for 30 seconds to evaluate the developability.

[0054] (3) Water resistance of the relief The cover film was peeled off from the printing plate precursor obtained in each Example and Comparative Example. A negative film containing a solid image and a grayscale negative film for sensitivity measurement were vacuum-attached to the photosensitive resin layer, and exposed under conditions of a grayscale sensitivity of 16±1 step using a chemical lamp FL20SBL-360 20 watts (main exposure). The photosensitive resin layer in the exposed area was observed under magnification using a 20x magnifying glass, and after confirming that there were no scratches on the photosensitive resin layer, the photosensitive resin layer was developed using a brush-type developing device DX-A3 (manufactured by Takano Machinery Works, Ltd.) with water at 30°C as the developer, and then dried at 60°C for 10 minutes to obtain a printing plate for evaluating water resistance. The development time was calculated from the thickness of the photosensitive resin layer and the development speed calculated in (2) and was set to twice that time.

[0055] The relief surface of the printing plate for evaluating water resistance was observed under magnification using a loupe with a magnification of 20 times, and the water resistance of the relief was evaluated according to the following criteria. 3: No change in surface condition observed before and after development 2: Brush scratches are visible on the relief surface. 1: Cracks are observed on the relief surface 0: Wear is observed on the relief surface.

[0056] (4) Image reproducibility The cover film was peeled off from the printing plate precursor obtained in each Example and Comparative Example. A negative film for evaluating image reproducibility containing a 150 line 3% halftone dot image and a grayscale negative film for measuring sensitivity were vacuum-attached to the photosensitive resin layer, and exposed under conditions of a grayscale sensitivity of 16±1 step using a chemical lamp FL20SBL-360 20 watts (main exposure). Thereafter, the plate was developed with water at 25°C using a brush-type developing device, and dried at 60°C for 10 minutes. Furthermore, a post-exposure was performed under the same conditions as the main exposure using a chemical lamp FL20SBL-360 20 watts to obtain a printing plate for evaluating image reproducibility.

[0057] A 150-line, 3% halftone dot formed in an area of ​​1 cm x 1 cm was observed using a 20x magnifying glass, and the reproducibility of the halftone dot was evaluated according to the following criteria. 4: No chipping observed 3: Missing dots are found in the outermost area 2: Chips are found in the inner area including the third row from the outermost circumference. 1: Missing areas are found in 20% or more of the total halftone dot area.

[0058] Next, the methods for producing the materials used in the examples and comparative examples will be described.

[0059] <Preparation of a support having an easy-adhesion layer> A mixture of 260 parts by mass of "Vylon" (registered trademark) 31SS (toluene solution of unsaturated polyester resin, manufactured by Toyobo Co., Ltd.) and 2 parts by mass of PS-8A (benzoin ethyl ether, manufactured by Wako Pure Chemical Industries, Ltd.) was heated at 70°C for 2 hours, cooled to 30°C, and 7 parts by mass of ethylene glycol diglycidyl ether dimethacrylate was added and mixed for 2 hours. Furthermore, 25 parts by mass of "Coronate" (registered trademark) 3015E (ethyl acetate solution of polyisocyanate resin, manufactured by Tosoh Co., Ltd.) and 14 parts by mass of EC-1368 (industrial adhesive, manufactured by Sumitomo 3M Co., Ltd.) were added and mixed to obtain coating solution 1 for easy adhesion layer.

[0060] Next, 50 parts by mass of "GOHSENOL" (registered trademark) KH-17 (polyvinyl alcohol with a saponification degree of 78.5 to 81.5 mol%, manufactured by Mitsubishi Chemical Corporation) was mixed in a mixed solvent of 200 parts by mass of "SOLMIX" (registered trademark) H-11 (alcohol mixture, manufactured by Nippon Alcohol Co., Ltd.) and 200 parts by mass of water at 70°C for 2 hours, and then 1.5 parts by mass of "BLEMMER" (registered trademark) G (glycidyl methacrylate, manufactured by Nippon Oil & Fats Corporation) was added and mixed for 1 hour. To this was further added 3 parts by weight of a copolymer having a weight ratio of (dimethylaminoethyl methacrylate) / (2-hydroxyethyl methacrylate) of 2 / 1 (manufactured by Kyoeisha Chemical Co., Ltd.), 5 parts by weight of "Irgacure" (registered trademark) 651 (benzyl methyl ketal, manufactured by Ciba-Geigy Corporation), 21 parts by weight of Epoxy Ester 70PA (acrylic acid adduct of propylene glycol diglycidyl ether, manufactured by Kyoeisha Chemical Co., Ltd.), and 20 parts by weight of ethylene glycol diglycidyl ether dimethacrylate, and mixed for 90 minutes. After cooling to 50°C, 0.1 parts by weight of "Megafac" (registered trademark) F-556 (manufactured by DIC Corporation) was added and mixed for 30 minutes to obtain coating liquid 2 for the easy-adhesion layer.

[0061] The above-mentioned coating solution 1 for easy adhesion layer was applied to a 250 μm-thick "Lumirror" (registered trademark) T60 (polyester film, manufactured by Toray Industries, Inc.) using a bar coater so that the dry film thickness was 40 μm, and the solvent was removed by heating for 3 minutes in an oven at 180° C. The above-mentioned coating solution 2 for easy adhesion layer was applied thereon using a bar coater so that the dry film thickness was 30 μm, and the coating was heated for 3 minutes in an oven at 160° C. to obtain a support having an easy adhesion layer.

[0062] <Creating cover film for analog version> "GOHSENOL" (registered trademark) AL-06 (partially saponified polyvinyl alcohol with a saponification degree of 91 to 94 mol%, manufactured by Mitsubishi Chemical Corporation) was applied to a 100 μm-thick "Lumilar" (registered trademark) S10 (polyester film, manufactured by Toray Industries, Inc.) that had been roughened to a surface roughness Ra of 0.1 to 0.6 μm, to a dry film thickness of 1 μm, and dried at 100° C. for 25 seconds to obtain a cover film for analog plates.

[0063] [Example 1] Partially saponified polyvinyl alcohol "GOHSENOL" KL-05 (average polymerization degree 500, saponification degree 80 mol%) manufactured by Mitsubishi Chemical Corporation was swollen in acetone, and 4.2 parts by mass of succinic anhydride were added to 100 parts by mass of "GOHSENOL" KL-05, and the mixture was stirred at 60°C for 6 hours to add a carboxyl group to the molecular chain of the partially saponified polyvinyl alcohol. The polymer was washed with acetone to remove unreacted succinic anhydride, and then dried. 100 parts by mass of this polymer was dissolved at 80°C in 200 parts by mass of a mixed solvent of ethanol / water = 30 / 70 (weight ratio). 8.3 parts by mass of glycidyl methacrylate was added thereto to introduce an ethylenic double bond into the partially saponified polyvinyl alcohol, thereby obtaining polyvinyl alcohol derivative A-1, which is component (A). A-1 had a vinyl alcohol structural unit, a vinyl acetate structural unit, and a structural unit represented by the following structural formula (3), and had a weight average molecular weight of 41,500.

[0064] [ka]

[0065] Next, 100 parts by mass of a mixed solvent of ethanol / water = 50 / 50 (weight ratio) was placed in a three-necked flask equipped with a stirring spatula and a cooling tube, and the obtained A-1 was added in the amount shown in Table 1 and dissolved by heating at 90 ° C for 2 hours. The obtained mixture was cooled to 70 ° C, and the other components shown in Table 1 were added and stirred for 30 minutes to obtain a photosensitive resin composition solution 1. For D1 in Table 1, "Pelex (registered trademark)" SS-L (manufactured by Kao Corporation) containing D1 as an active ingredient was added so that the content of the active ingredient was as shown in Table 1.

[0066] The photosensitive resin composition solution 1 obtained as described above was cast onto the easy-adhesion layer side of the support having the easy-adhesion layer, and dried at 60° C. for 2.5 hours to form a photosensitive resin layer. At this time, the plate thickness after drying (support having the easy-adhesion layer + photosensitive resin layer) was adjusted to 0.95 mm.

[0067] A mixed solvent of water / ethanol = 50 / 50 (weight ratio) was applied onto the photosensitive resin layer thus obtained, and the cover film for the analog plate was pressed onto the surface to obtain photosensitive resin printing plate precursor 1. The evaluation results of the obtained photosensitive resin printing plate precursor 1 are shown in Table 1.

[0068] [Examples 2 to 8] Photosensitive resin printing plate precursors 2 to 8 were obtained in the same manner as in Example 1, except that the type and amount of each component was changed as shown in Table 1. The evaluation results are shown in Table 1. For D1 in Table 1, "Pelex (registered trademark)" SS-L (manufactured by Kao Corporation) containing D1 as the active ingredient, and for D2, "Latemul" (registered trademark) E-118B (manufactured by Kao Corporation) containing D2 as the active ingredient were added so that the active ingredients were contained at the contents shown in Table 1.

[0069] [Example 9] Photosensitive resin printing plate precursor 9 was obtained in the same manner as in Example 4, except that "GOHSENOL" KL-05 was used instead of polyvinyl alcohol derivative A-1. The evaluation results are shown in Table 1.

[0070] [Example 10] Partially saponified polyvinyl alcohol "GOHSENOL" KL-05 (average polymerization degree 500, saponification degree 80 mol%) manufactured by Mitsubishi Chemical Corporation was swollen in acetone, and 4.2 parts by mass of succinic anhydride were added to 100 parts by mass of "GOHSENOL" KL-05, and the mixture was stirred at 60°C for 6 hours to add a carboxyl group to the molecular chain of the partially saponified polyvinyl alcohol. The polymer was washed with acetone to remove unreacted succinic anhydride, and then dried. 100 parts by mass of this polymer was dissolved at 80°C in 200 parts by mass of a mixed solvent of ethanol / water = 30 / 70 (weight ratio). 8.3 parts by mass of an epoxy compound "CYCLOMER" (registered trademark) M100 (manufactured by Daicel Corporation) was added thereto to introduce a cyclic structure and an ethylenic double bond into the partially saponified polyvinyl alcohol, thereby obtaining polyvinyl alcohol derivative A-2, which is the component (A). A-2 had a vinyl alcohol structural unit, a vinyl acetate structural unit and a structural unit represented by the following structural formula (4), and had a weight average molecular weight of 41,500.

[0071] [ka]

[0072] A photosensitive resin printing plate precursor 10 was obtained in the same manner as in Example 4, except that the polyvinyl alcohol derivative A-2 was used instead of the polyvinyl alcohol derivative A-1. The evaluation results are shown in Table 1.

[0073] [Comparative Examples 1 to 4] Photosensitive resin printing plate precursors 11 to 14 were obtained in the same manner as in Example 1, except that the type and amount of each component was changed as shown in Table 2. The evaluation results are shown in Table 2.

[0074] [Table 1]

[0075] [Table 2]

Claims

1. A photosensitive resin printing plate original having a photosensitive resin layer on a support, wherein the photosensitive resin layer contains at least polyvinyl alcohol and / or its derivative (A), a compound having an ethylenic double bond (B), a photopolymerization initiator (C), and a surfactant (D) having an alkyl group and a sulfo group or its salt and not containing fluorine.

2. The photosensitive resin printing plate original according to claim 1, wherein the surfactant (D) further has a polyoxyethylene group.

3. The photosensitive resin printing plate original according to claim 1 or 2, wherein the surfactant (D) further has an aromatic ring.

4. The photosensitive resin printing plate original according to claim 1 or 2, wherein the surfactant (D) is contained in the photosensitive resin layer in an amount of 3 to 15% by mass.

5. A method for manufacturing a printing plate, comprising: an exposure step of irradiating ultraviolet rays to the photosensitive resin layer of the photosensitive resin printing plate original according to claim 1 or 2 to photocure the exposed portion of the photosensitive resin layer; and a development step of removing the uncured portion of the photosensitive resin layer with a developer mainly composed of water.

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