Photosensitive resin printing plate master and method for manufacturing a printing plate using the same

Abstract

To provide a photosensitive resin printing plate master that can suppress warping of the printing plate and warping of the printing plate after ink immersion. [Solution] A photosensitive resin printing plate master having a photosensitive resin layer on a support containing polyvinyl alcohol and / or its derivative (A), a compound having an ethylenic double bond (B), a photopolymerization initiator (C), and a compound having a structure represented by the following general formula (1) (D). [Formula 1] TIFF2026112540000007.tif20158 (In the above general formula (1), R represents an alkyl group having 10 or more carbon atoms. n represents an integer from 1 to 20.)

Description

[Technical Field]

[0001] The present invention relates to a photosensitive resin printing plate, a method for manufacturing a printing plate using the same, and a method for manufacturing a printed material. [Background technology]

[0002] Polyvinyl alcohol and its derivatives are water-soluble polymers with excellent film-forming properties, and are therefore widely used, for example, in the photosensitive resin layer that forms the relief of photosensitive resin printing plates.

[0003] As a photosensitive printing plate master using polyvinyl alcohol or its derivatives in the photosensitive resin layer, for example, a photosensitive printing plate having at least a support (D) and a photosensitive resin layer (E) formed from a photosensitive resin composition containing a water-soluble polymer or water-swellable polymer (A) such as polyvinyl alcohol, an ethylenically unsaturated compound (B) and a photopolymerization initiator (C) (see, for example, Patent Document 1), a resin (A) containing ionic functional groups such as polyvinyl alcohol, a photopolymerization initiator (B), a photopolymerizable monomer (C), and an ionic functional group capable of forming a counterion with the resin (A) Some proposed flexographic printing plates include a photosensitive resin plate made using a photosensitive resin composition containing a fluorine-containing compound (D) (see, for example, Patent Document 2), and a flexographic printing plate having at least a support and a photosensitive resin layer, wherein the photosensitive resin layer contains at least a hydrophilic plasticizer (component A), an ethylenically unsaturated group-containing monomer having a chemical structure with 2 or more ethylene oxide repeats and a hydroxyl group (component B), and a hydrophilic polymer such as partially saponified polyvinyl alcohol or a partially saponified polyvinyl alcohol derivative (component C) (see, for example, Patent Document 3). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-182247 [Patent Document 2] International Publication No. 2018 / 088336 [Patent Document 3] Japanese Patent Publication No. 2024-51371 [Overview of the project] [Problems that the invention aims to solve]

[0005] The photosensitive resin printing plates described in Patent Documents 1 and 2 use plasticizers such as polyhydric alcohols and ethylene glycols to increase the flexibility of the photosensitive resin layer. These plasticizers increase the flexibility of the relief in the printing plate formed from the photosensitive resin printing plate, and also have the effect of suppressing warping of the printing plate because the hydroxyl groups in the plasticizer interact with the hydroxyl groups of polyvinyl alcohol and / or its derivatives. On the other hand, in recent years, inks that harden with active energy rays such as ultraviolet rays and electron beams have attracted attention as printing inks from an environmental perspective. The aforementioned plasticizers are easily extracted from the relief into the ink during printing, especially in printing using active energy ray curing inks, which has led to a problem where the internal stress of the relief increases after ink immersion, making it prone to warping.

[0006] Furthermore, the flexographic printing plate described in Patent Document 3 had a problem in that when a water-based developer was used in the development process, the hydrophilic plasticizer was easily dissolved into the developer, which increased the internal stress of the relief in the printing plate and made it prone to warping.

[0007] In view of the problems of the prior art, the present invention aims to provide a photosensitive resin printing plate that can suppress warping of the printing plate and warping of the printing plate after ink immersion. [Means for solving the problem]

[0008] To achieve the above objective, the present invention mainly has the following configuration. [1] A photosensitive resin printing plate master having a photosensitive resin layer on a support containing polyvinyl alcohol and / or its derivative (A), a compound having an ethylenically double bond (B), a photopolymerization initiator (C), and a compound having a structure represented by the following general formula (1) (D).

[0009] [ka]

[0010] (In the above general formula (1), R represents an alkyl group having 10 or more carbon atoms. n represents an integer from 1 to 20.) [2] The photosensitive resin printing plate original according to [1], wherein the content of (D) in the photosensitive resin layer is 2 to 30 parts by mass per 100 parts by mass of (A). A method for manufacturing a printing plate, comprising: an exposure step of irradiating the photosensitive resin layer of the photosensitive resin printing plate master described in [3] [1] or [2] with ultraviolet light to photo-cure the exposed portion of the photosensitive resin layer; and a development step of removing the uncured portion of the photosensitive resin layer with a developing solution mainly composed of water. A method for manufacturing a printed material, comprising a transfer step of transferring an active energy ray-curable ink to a substrate using a printing plate obtained by the manufacturing method described in [4][3], and an active energy ray irradiation step of irradiating the transferred active energy ray-curable ink with active energy rays. [Effects of the Invention]

[0011] According to the photosensitive resin printing plate original of the present invention, warping of the printing plate and warping of the printing plate in printing using active energy ray curable printing ink can be suppressed. [Modes for carrying out the invention]

[0012] The photosensitive resin printing plate original plate of the present invention (hereinafter may be abbreviated as "printing plate original plate") 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 compound (D) having a structure represented by the following general formula (1). By having a photosensitive resin layer, for example, by irradiating ultraviolet rays in an image pattern and removing the non-image areas by a developer or laser irradiation, a desired relief can be formed on the support. The photosensitive resin layer may have two or more layers. The support has the function of holding the photosensitive resin layer and the relief. Further, if necessary, a cover film may be provided on the photosensitive resin layer. By having 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-adhesive layer may be provided between the photosensitive resin layer and the cover film.

[0013] 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.

[0014] From the viewpoints of handleability and flexibility, the thickness of the support is preferably 100 to 350 μm.

[0015] The support is preferably subjected to an easy adhesion treatment, which can improve the adhesion with the photosensitive resin layer. Examples of the easy adhesion treatment method include mechanical treatment such as sandblasting, physical treatment such as corona discharge, and chemical treatment such as coating. Among these, from the viewpoint of adhesion, it is preferable to provide an easy adhesion layer by coating.

[0016] The photosensitive resin layer contains at least polyvinyl alcohol and / or its derivative (A) (hereinafter sometimes abbreviated as "component (A)"), a compound having an ethylenic double bond (B) (hereinafter sometimes abbreviated as "component (B)"), a photopolymerization initiator (C) (hereinafter sometimes abbreviated as "component (C)"), and a compound having the structure represented by the general formula (1) described above (D) (hereinafter sometimes abbreviated as "component (D)"). When light is irradiated onto such a photosensitive resin layer, free radicals are generated from component (C) in the photosensitive resin layer. The generated free radicals undergo radical polymerization with component (B), and a crosslinked structure can be formed to create a relief with excellent image reproducibility for obtaining a desired printed image.

[0017] (A) component has the function of imparting structural strength to a photosensitive resin layer or a relief matrix, can improve image reproducibility, and has the property of being difficult to swell in an active energy ray-curable printing ink. Therefore, it has been suitably used for a printing plate original for printing using an active energy ray-curable printing ink. On the other hand, (A) component has a large number of hydroxyl groups in the molecule, and due to the interaction of these hydroxyl groups within and between molecules, there is a problem that the relief shrinks and warping is likely to occur. As described above, plasticizers such as polyhydric alcohols and ethylene glycols that have been used to enhance the flexibility of the photosensitive resin layer interact with the hydroxyl groups of (A) component, so they have the effect of suppressing the shrinkage of the relief of the printing plate and suppressing warping. However, these plasticizers are particularly likely to be extracted from the relief into the ink during printing in printing using an active energy ray-curable printing ink, and there is a problem that the internal stress of the relief increases after ink immersion and warping is likely to occur. Further, the hydrophilic plasticizer described in Patent Document 3 is likely to be eluted into the developer in the developing step using a developer mainly composed of water, so there is a problem that the internal stress of the relief increases in the printing plate and warping is likely to occur. Therefore, in the present invention, as the (D) component, a compound having a structure represented by the following general formula (1) is used. The (D) component has a hydrophilic polyoxyethylene part, and since the hydroxyl group interacts with the hydroxyl group of (A) component, it can suppress the shrinkage of the relief of the printing plate and suppress warping. Further, the long-chain alkyl group represented by R in the general formula (1) is a hydrophobic group and has the function of protecting the formed hydrogen bond from interaction with other substances. Therefore, even when the relief of the printing plate comes into contact with an active energy ray-curable printing ink, the hydrogen bond between (A) component and (D) component can be maintained, and warping of the printing plate after ink immersion can be suppressed. Furthermore, the long-chain alkyl group represented by R in the general formula (1) moderately suppresses the compatibility with the ink and the developer, and is difficult to be extracted and eluted into the ink and the developer. Therefore, warping of the printing plate can be suppressed, and warping can also be suppressed in printing using an active energy ray-curable printing ink.

[0018] [Chemical formula]

[0019] In the general formula (1) above, R represents an alkyl group having 10 or more carbon atoms, and n represents an integer from 1 to 20.

[0020] (A) Among the components, polyvinyl alcohol is a general term for (i) polyvinyl alcohol with a degree of saponification of 100%, consisting of vinyl alcohol structural units, and partially saponified polyvinyl alcohol having (i) vinyl alcohol structural units and (ii) vinyl acetate structural units. Polyvinyl alcohol derivatives refer to those in which functional groups have been introduced into the main chain and / or side chains, or which have other structural units. Two or more of these may be contained.

[0021] (A) When imparting photosensitivity to component, the polyvinyl alcohol derivative is preferably (i) a vinyl alcohol structural unit, (ii) a vinyl acetate structural unit, and (iii) a structural unit represented by the following general formula (2) and / or a structural unit represented by general formula (3). In particular, the structural unit represented by the following general formula (2) and / or a structural unit represented by general formula (3) can further improve image reproducibility by having an ethylenically double bond. Furthermore, since the ethylenically double bond crosslinks upon exposure, the water resistance of the relief during development is improved, and brush scratches, cracks, and abrasion on the relief surface can be suppressed.

[0022] [ka]

[0023] In general formulas (2) and / or (3), R 1 R represents a divalent organic group having an alkylene group, 2 This represents a hydrogen atom or a methyl group. This enhances the retention of component (B) in the photosensitive resin layer and suppresses bleed-out.

[0024] Examples of the divalent organic group having an alkylene group include, for example, -CpH 2p COO-CqH 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.

[0025] R in the general formula (2) and / or (3) 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 in the case of a methyl group, so the sensitivity of the photosensitive resin composition can be improved. Depending on the desired sensitivity, a hydrogen atom or a methyl group can be appropriately selected.

[0026] The content of the vinyl alcohol structural unit in the polyvinyl alcohol derivative (i) is preferably 65 to 90 mol% with respect to the total of (i) to (iii). By setting the content of (i) to 65 mol% or more, the developability with a developer mainly composed of water can be improved. On the other hand, by setting the content of (i) to 90 mol% or less, the compatibility with the component (B) can be further improved. The content of the vinyl acetate unit (ii) is preferably 10 to 35 mol% with respect to the total of (i) to (iii). The total content of the structural unit represented by the general formula (2) and the structural unit represented by the general formula (3) in (iii) 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 a developer mainly composed of water can be improved.

[0027] The degree of saponification of component (A) is preferably 65 to 90 mol%. By setting the degree of saponification of component (A) to 65 mol% or higher, the solubility in developing solutions mainly composed of water can be improved. On the other hand, by setting the degree of saponification of component (A) to 90 mol% or lower, the compatibility with component (B) can be improved.

[0028] The average degree of polymerization of component (A) is preferably 300 to 2,000. By setting the average degree of polymerization of component (A) to 300 or higher, the bleed-out of low molecular weight components such as component (B) from the photosensitive resin layer can be suppressed. In addition, the photosensitive resin layer can be easily formed. On the other hand, by setting the average degree of polymerization of component (A) to 2,000 or lower, the fluidity of the photosensitive resin composition can be improved, and the photosensitive resin layer can be easily formed.

[0029] Here, the degree of saponification and average degree of polymerization of component (A) in this invention are values ​​measured according to JIS K 6726-1994 (Test Method for Polyvinyl Alcohol). Furthermore, if two or more components (A) are contained, the degree of saponification and average degree of polymerization refer to the total of the two or more components (A).

[0030] As a method for producing the polyvinyl alcohol derivative of component (A), for example, in the case of a polyvinyl alcohol derivative having the structural units of (i) to (iii) described above, examples include: (1) a method in which a partially saponified polyvinyl alcohol is reacted with an acid anhydride to introduce reactive groups such as carboxyl groups into the polymer side chains starting from the hydroxyl groups of the partially saponified polyvinyl alcohol, and then reacting these reactive groups with an unsaturated epoxy compound; (2) a method in which a copolymer of vinyl acetate and an unsaturated carboxylic acid, an unsaturated carboxylate salt, and / or an unsaturated carboxylic acid ester is partially saponified, and the carboxyl groups of this polymer are reacted with an unsaturated epoxy compound; and (3) a method in which a carboxylic acid compound having an ethylenic double bond is reacted starting from the hydroxyl groups of the partially saponified polyvinyl alcohol.

[0031] In the photosensitive resin layer of the printing plate master of the present invention, the content of component (A) is preferably 25 to 70% by mass of the solid content. Note that if two or more types of component (A) are included, the total content refers to the total content. A content of 25% by weight or more of the solid content can improve the print resistance of the printing plate obtained from the photosensitive resin printing plate master. On the other hand, a content of component (A) of 70% by weight or less of the solid content is preferable, as this can improve the flexibility of the printing plate obtained from the photosensitive resin printing plate master. Note that if two or more types of component (A) are included, the total content refers to the total content.

[0032] In the present invention, component (B) refers to a substance 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.

[0033] 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, and tetrahydrofurfuryl(meth)acrylate. Two or more of these may be included. 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), compounds having polar groups such as hydroxyl groups, carboxyl groups, amino groups, and sulfo groups, or heterocyclic compounds are preferred because they have good compatibility with component (A).

[0034] The preferred content of component (B) in the photosensitive resin layer is 5 to 200 parts by mass per 100 parts by mass of component (A). Note that if two or more types of component (B) are present, the content of component (B) refers to their total content.

[0035] (C) Component preferably has the function of generating radicals by self-decomposition or hydrogen abstraction upon light absorption. Examples include benzoin alkyl ethers, benzophenones, anthraquinones, benzyls, acetophenones, and diacetyls. 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-methylpropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, and 2-benzyl-2-(dimethylamino)-4'-morpholinobrillophenone are preferably used.

[0036] The content of component (C) in the photosensitive resin layer is preferably 0.1 to 20 parts by mass per 100 parts by mass of component (A). Note that if two or more types of component (C) are present, the content of component (C) refers to their total content.

[0037] Component (D) has a structure represented by the general formula (1). In the general formula (1), R represents an alkyl group having 10 or more carbon atoms, and n represents an integer from 1 to 20. That is, component (D) is a polyoxyethylene alkyl ether and is a nonionic surfactant with a non-dissociating hydrophilic group. The polyoxyethylene portion in general formula (1) is hydrophilic, and its hydroxyl group interacts with the hydroxyl group of component (A), thus suppressing the shrinkage of the relief of the printing plate and reducing warping. On the other hand, the alkyl group having 10 or more carbon atoms represented by R in general formula (1) is a hydrophobic group and has the effect of protecting the formed hydrogen bonds from interaction with other substances. Therefore, even when the relief of the printing plate comes into contact with an active energy ray curable printing ink, the hydrogen bond between component (A) and component (D) is maintained, and warping of the printing plate after ink immersion can be suppressed. Furthermore, these long-chain alkyl groups moderately suppress compatibility with inks and developers, making them less susceptible to extraction and elution by inks and developers. This suppresses warping of the printing plate, and can also suppress warping in printing using active energy ray-curable printing inks. The alkyl group preferably has 14 or more carbon atoms. On the other hand, the alkyl group preferably has 20 or fewer carbon atoms, which improves compatibility with component (A) and suppresses the bleed-out of component (D) from the photosensitive resin layer.

[0038] In general formula (1), n ​​is an integer between 1 and 20. By setting n to 1 or greater, the bleed-out of component (D) from the photosensitive resin layer can be suppressed. On the other hand, by setting n to 20 or less, the compatibility with component (A) is improved, and the bleed-out of component (D) from the photosensitive resin layer can be suppressed. Furthermore, the hydrophilicity within the molecule of component (D) is moderately suppressed, which further suppresses elution into the water-based developer during the development process, and further suppresses warping of the printing plate. n is preferably 12 or less. Moreover, n is more preferably 8 or less, which can suppress foaming of the developer during the development process.

[0039] The content of component (D) in the photosensitive resin layer is preferably 2 to 30 parts by mass per 100 parts by mass of (A). By setting the content of component (D) to 2 parts by mass or more, the warping of the printing plate and the warping of the printing plate after ink immersion can be further suppressed. The content of component (D) is more preferably 4 parts by mass or more, and even more preferably 8 parts by mass or more. On the other hand, by setting the content of component (D) to 30 parts by mass or less, the bleed-out of component (D) from the photosensitive resin layer can be suppressed. The content of component (D) is more preferably 28 parts by mass or less, and even more preferably 23 parts by mass or less. Note that if two or more types of component (D) are included, the content of component (D) refers to the total content.

[0040] The photosensitive resin layer may, in addition to components (A) to (D), optionally contain binder polymers other than component (A), compatibility aids, polymerization inhibitors, dyes, pigments, surfactants other than component (D), defoamers, UV absorbers, fragrances, etc.

[0041] The thermal stability can be improved by including a polymerization inhibitor in the photosensitive resin layer. Examples of polymerization inhibitors include phenols, hydroquinones, catechols, and hydroxyamine derivatives. One or more of these may be included. The content of the polymerization inhibitor in the photosensitive resin layer is preferably 0.001 to 5% by mass.

[0042] The thickness of the photosensitive resin layer is preferably 100 μm or more, which ensures the height of the relief on the printing plate and suppresses the so-called bottoming-out phenomenon where ink adheres to the support surface during printing. On the other hand, the thickness of the photosensitive resin layer is preferably 2.0 mm or less, which can improve print reproducibility.

[0043] Examples of cover films 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 also be roughened to improve adhesion to the original film. Methods for roughening the surface include sandblasting, chemical etching, and coating with a matte particle-containing coating agent.

[0044] Furthermore, when the printing plate master 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 in place from the mask layer elements, and then exposed and developed, the printing plate master may further have a thermal mask layer. Preferably, the thermal mask layer substantially blocks ultraviolet light, absorbs infrared laser light during drawing, and is instantaneously partially or completely sublimated or melted by the heat. This creates a difference in optical density between the laser-irradiated and unirradiated areas, allowing it to perform a function similar to that of conventional original image films. When the printing plate master has a thermal mask layer, an adhesion adjustment layer may be provided between the photosensitive resin layer and the thermal mask layer, and a release assist layer may be provided between the thermal mask layer and the cover film.

[0045] Examples of thermal mask layers, adhesion adjusting layers, and release aid layers include those described in International Publication No. 2017 / 038970.

[0046] The printing plate master of the present invention is preferably a flexographic printing plate master. Generally, flexographic printing is characterized by the use of low viscosity ink and low printing pressure. For this reason, there is a growing need for flexographic printing plates used in flexographic printing to suppress warping. The printing plate master of the present invention can suppress warping of the printing plate and warping of the printing plate after ink immersion, and is therefore suitable for use as a flexographic printing plate master.

[0047] Next, we will explain the method for manufacturing a printing plate, using the case where a photosensitive resin layer and a cover film are provided on a support as an example.

[0048] For example, components (A) to (D) and other additives as needed are added to a solvent, heated and dissolved while stirring to obtain a photosensitive resin composition solution for the photosensitive resin layer. Examples of solvents include water / alcohol mixed solvents.

[0049] A photosensitive resin composition solution is cast onto a support having an easily adhesive layer as needed, and dried to form a photosensitive resin layer. Furthermore, a cover film coated with an anti-adhesion layer as needed is adhered to the photosensitive resin layer to obtain a printing plate master.

[0050] Next, the method for manufacturing a printing plate according to the present invention will be described. The method for manufacturing a printing plate according to the present invention comprises an exposure step of irradiating the photosensitive resin layer of the printing plate master with ultraviolet light to photo-harden the exposed portion of the photosensitive resin layer, and a step of removing the non-image portion of the photosensitive resin layer. Examples of the step of removing the non-image portion of the photosensitive resin layer include a developing step of removing the unhardened portion of the photosensitive resin layer with a developing solution mainly composed of water, and an engraving step of removing the non-image portion of the photosensitive resin layer with a laser.

[0051] In the exposure process, if a cover film is present, it is preferable to adhere a negative or positive original image film to the photosensitive resin layer from which the cover film has been peeled off, and irradiate it with ultraviolet light of a wavelength of 300 to 400 nm to photo-cure the exposed portion of the photosensitive resin layer. For ultraviolet 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, or a UV-LED lamp.

[0052] If the printing plate master of the present invention has a thermal mask layer, it is preferable to draw the thermal mask layer with infrared laser light, melt a part or all of the thermal mask layer to form an image mask, and irradiate the exposed portion of the photosensitive resin layer with ultraviolet light of wavelength 300 to 400 nm through the image mask to photo-cure it.

[0053] When forming a relief from the printing plate master of the present invention by an engraving process, it is preferable to irradiate the photosensitive resin layer surface with ultraviolet light having a wavelength of 300 to 400 nm during the exposure process to photo-cure it.

[0054] In the developing process, it is preferable to remove the uncured portion by dissolving it using a spray-type developing device or a brush-type washing machine. Examples of developing solutions include water and / or organic solvents, and it is preferable that the solution mainly consists of water.

[0055] Furthermore, if necessary, a post-exposure step of irradiating with ultraviolet light after development may be included. The post-exposure step can further strengthen the relief by reacting the unreacted (B) component.

[0056] In the engraving process, it is preferable to irradiate the photosensitive resin layer, which has been photocured in the exposure process, with a laser to create a pattern and engrave away the non-image areas.

[0057] Furthermore, if necessary, the process may include steps such as rinsing the relief surface with water or a water-containing liquid after engraving to remove engraving residue generated by laser irradiation, drying the relief, and irradiating the relief with active light to further crosslink it.

[0058] Next, a method for manufacturing printed materials will be described. Examples of printing methods using printing plates with relief include relief printing such as flexographic printing and dry offset printing, which transfers ink from the printing plate to the substrate via a blanket. Flexographic printing is a type of relief printing in which ink is supplied to the printing plate using an anilox roll. Compared to other relief printing methods and dry offset printing, flexographic printing generally uses inks with lower viscosity, and the printing pressure is set low to suppress ink deformation due to printing pressure. For this reason, there is a growing need to suppress warping of flexographic printing plates. Since the warping of the printing plate and the warping of the printing plate after ink immersion can be suppressed by the present invention, the printing plate of the present invention can be suitably used in flexographic printing.

[0059] The present invention provides a method for manufacturing printed materials, comprising a transfer step of transferring an active energy ray-curable ink (hereinafter sometimes abbreviated as "ink") onto a substrate using a printing plate obtained by the method described above, and an active energy ray irradiation step of irradiating the transferred ink with active energy rays.

[0060] In the transfer process, for example, the printing plate obtained by the method described above is mounted on the plate cylinder of a printing press, ink is supplied to the printing plate, and the ink is transferred from the printing plate to the substrate. A flexographic printing press is preferred as the printing press, and it is preferable to supply ink from the ink pan to the printing plate via anilox rolls and transfer the ink to the substrate.

[0061] Examples of substrates for printing include paper and plastic film.

[0062] Examples of active energy ray curing inks include inks that cure with ultraviolet light and inks that cure with electron beams. Specifically, these include inks containing pigments, resins such as acrylic oligomers, acrylate monomers, and polymerization initiators as needed. Examples of ultraviolet curing flexographic printing inks include PHA (manufactured by T&K TOKA Corporation), "FLASH DRY (registered trademark)" (manufactured by Toyo Ink Co., Ltd.), and UVAFLEXY77 (manufactured by Zeller+Gmelin). Examples of EB inks include SunBeam EB Flexo (manufactured by SunChemical).

[0063] In the active energy ray irradiation process, ultraviolet rays and electron beams are preferred as the active energy rays. Examples of ultraviolet irradiation devices include high-pressure mercury lamps, xenon lamps, metal halide lamps, and light-emitting diodes (LEDs). Among these, from the viewpoint of power saving, an ultraviolet (LED-UV) irradiation device using a light-emitting diode that emits emission lines with a wavelength of 350 to 420 nm as the light source is preferred. As for electron beams, energy rays of 100 to 500 eV are preferred. [Examples]

[0064] The present invention will be specifically illustrated below with reference to examples, but the present invention is not limited to these examples. The evaluation methods in the examples and comparative examples are shown below.

[0065] (1) Degree of saponification and average degree of polymerization of component (A) The degree of saponification and average degree of polymerization of polyvinyl alcohol and polyvinyl alcohol derivatives used in each example and comparative example were measured according to JIS K 6726-1994 (Test methods for polyvinyl alcohol).

[0066] (2) Bleed-out amount From the printing plates obtained in each example and comparative example, the cover film was peeled off, and 32 samples measuring 8 cm x 8 cm were cut. Each sample was stored in a constant temperature and humidity chamber at 40°C and 80% relative humidity for 7 days. Bleed-out components were wiped from the surface of each sample using 8 cm x 8 cm oil-absorbing paper, and the weight change of the oil-absorbing paper before and after wiping was measured. The average of these values ​​was calculated to determine the weight change per unit area (g / m²). 2 The amount of bleed-out was calculated by converting it to ( ).

[0067] (3) Curvature of the printing plate (3-1) Initial amount of curvature The cover film was peeled off the printing plates obtained in each example and comparative example. A negative film containing a solid image and a grayscale negative film for sensitivity measurement were vacuum-pressed onto the photosensitive resin layer, and exposed to light using a DX-A3NEO letterpress printing machine (manufactured by Takano Machinery Co., Ltd.) equipped with a UV-LED under conditions that resulted in a grayscale sensitivity of 16±1 stops (main exposure). Subsequently, using the DX-A3NEO letterpress printing machine (manufactured by Takano Machinery Co., Ltd.), the plates were developed for 120 seconds with 30°C water as the developer, and then dried at 60°C for 10 minutes to obtain a printing plate. From the obtained printing plates, five circular evaluation samples with a diameter of 10 cm were cut out using a circle cutter. The evaluation samples were placed on a smooth surface with the polyester film side (support side) facing down in an environment of 25°C and 60RH%, and the height of the highest point where the polyester film was floating above the surface was measured with a ruler. The average height of the highest point of the five samples was taken as the initial warp.

[0068] (3-2) Amount of warping after ink immersion The printing plates whose initial warp was measured in (3-1) were immersed in UV Flexo J Sumi PHA-L03 (manufactured by T&K TOKA Corporation), a representative UV-curing ink, at 40°C for 6 hours. After that, the UV-curing ink was wiped off with a cloth, and the warp was measured again in the same manner as in (3-1), and this was recorded as the warp after ink immersion.

[0069] (4) Foaming of the developing solution In each example and comparative example, the photosensitive resin layer of the printing plate obtained was dissolved in water to a concentration of 1.0% by mass to prepare an aqueous solution. 20 mL of the resulting aqueous solution was added to a 100 mL graduated cylinder with a stopper, and then shaken 20 times at 1-second intervals so that the liquid surface was inverted. After standing for 1 minute, the height of the bubbles from the liquid surface (mm) was measured. A lower bubble height indicates that foaming of the developer solution is suppressed.

[0070] Next, the materials used in each example and comparative example will be described.

[0071] (A) component <Manufacturing Example 1: Polyvinyl Alcohol Derivative> Partially saponified polyvinyl alcohol "Gosenol®" NK-05R (average degree of polymerization: 500, degree of saponification: 72 mol%) manufactured by Mitsubishi Chemical Corporation was swollen in acetone. 4.2 parts by mass of succinic anhydride were added to 100 parts by mass of "Gosenol" NK-05R, and the mixture was stirred at 60°C for 6 hours to add carboxyl groups to the molecular chains of the partially saponified polyvinyl alcohol. This polymer was washed with acetone to remove unreacted succinic anhydride, and then dried. 100 parts by mass of this polymer was dissolved in 200 parts by mass of a mixed solvent of ethanol / water = 30 / 70 (mass ratio) at 80°C. 8.3 parts by mass of glycidyl methacrylate were added to introduce an ethylenic double bond into the partially saponified polyvinyl alcohol, obtaining the polyvinyl alcohol derivative, which is component (A). The obtained polyvinyl alcohol derivative consists of a vinyl alcohol structural unit, a vinyl acetate structural unit, and, in the following general formula (2), R 1 :-C2H4-COO-CH(OH)―C2H4-OC(O), R 2 It has a structural unit consisting of a methyl group, an average degree of polymerization of 500, a degree of saponification of 71 mol%, and a weight-average molecular weight of 44,500.

[0072] [ka]

[0073] (B) Component • “Bremmer (registered trademark)” PE90: Manufactured by NOF Corporation, polyethylene glycol monomethacrylate (Mw: approx. 170) • “Bremmer (registered trademark)” AE400: Manufactured by NOF Corporation: Polyethylene glycol monomethacrylate (Mw: approx. 513) • Epoxy ester 70PA: Manufactured by Kyoeisha Chemical Co., Ltd., acrylic acid adduct of propylene glycol diglycidyl ether (Mw: approx. 304) (C) Component • 2,2-Dimethoxy-1,1-diphenylethane-1-one: Manufactured by Sigma-Aldrich (D) Component • “Neugen (registered trademark)” NL-30: Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene lauryl ether (in general formula (1), the number of carbon atoms in R: 12, n: 3, HLB: 8.1) • “Neugen (registered trademark)” TDS-30: Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene tridecyl ether (in general formula (1), number of carbon atoms in R: 13, n: 3, HLB: 8.0) • “Neugen (registered trademark)” TDS-50: Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene tridecyl ether (in general formula (1), the number of carbon atoms in R: 13, n: 5, HLB: 10.5) • “Neugen (registered trademark)” TDS-120: Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene tridecyl ether (in general formula (1), the number of carbon atoms in R: 13, n: 12, HLB: 14.8) • "Emulgen (registered trademark)" 210P: Manufactured by Kao Corporation, polyoxyethylene cetyl ether (in general formula (1), the number of carbon atoms in R: 16, n: 6, HLB: 10.7) • “Emulgen (registered trademark)” 408: Manufactured by Kao Corporation, polyoxyethylene oleyl ether (in general formula (1), R has 18 carbon atoms, n: 6, HLB: 10.0) others • Trimethylolpropane: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Glycerin: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. • TMP-60: Manufactured by Nippon Emulsifier Co., Ltd., trimethylolpropane tri(ethylene glycol) ether (Mw: approx. 400) • N-(ammonium oxy)-N-nitrosophenylamine: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0074] Next, the methods for preparing the materials used in each example and comparative example will be described.

[0075] <Manufacturing Example 2: Fabrication of a support with an easy-to-adhere layer> A mixture of 260 parts by mass of "Byron®" 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 Fujifilm Wako Pure Chemical Industries, Ltd.) was heated at 70°C for 2 hours, then 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®" 3015E (ethyl acetate solution of polyvalent isocyanate resin, manufactured by Tosoh Corporation) and 14 parts by mass of EC-1368 (industrial adhesive, manufactured by Sumitomo 3M Limited) were added and mixed to obtain coating solution 1 for easy-adhesion layer.

[0076] Next, 50 parts by mass of “Gosenol®” KH-17 (polyvinyl alcohol with a saponification degree of 78.5 to 81.5 mol%, manufactured by Mitsubishi Chemical Corporation) was mixed with 200 parts by mass of “Solmix®” H-11 (alcohol mixture, manufactured by Nippon Alcohol Co., Ltd.) and 200 parts by mass of water in a mixed solvent at 70°C for 2 hours. Then, 1.5 parts by mass of “Bremmer®” G (glycidyl methacrylate, manufactured by Nippon Oil & Fats Co., Ltd.) was added and mixed for 1 hour. To this, 3 parts by mass of a copolymer (manufactured by Kyoeisha Chemical Co., Ltd.) with a weight ratio of (dimethylaminoethyl methacrylate) / (2-hydroxyethyl methacrylate) 2 / 1, 5 parts by mass of "Irgacure®" 651 (benzyl methyl ketal, manufactured by Ciba-Geigy Co., Ltd.), 21 parts by mass of epoxy ester 70PA (acrylic acid adduct of propylene glycol diglycidyl ether, manufactured by Kyoeisha Chemical Co., Ltd.), and 20 parts by mass of ethylene glycol diglycidyl ether dimethacrylate were added and mixed for 90 minutes. After cooling to 50°C, 0.1 parts by mass of "Megafac®" F-556 (manufactured by DIC Corporation) were added and mixed for 30 minutes to obtain coating liquid 2 for easy adhesion layer.

[0077] On a 188 μm thick "Lumirror®" T60 (polyester film, manufactured by Toray Industries, Inc.), the easy-adhesion coating liquid 1 was applied using a bar coater to a dry film thickness of 40 μm, and the solvent was removed by heating in a 180°C oven for 3 minutes. On the same surface, the easy-adhesion coating liquid 2 was applied using a bar coater to a dry film thickness of 30 μm, and the material was heated in a 160°C oven for 3 minutes to obtain a support having an easy-adhesion layer.

[0078] <Manufacturing Example 3: Fabrication of Cover Film> A 100 μm thick "Lumirror®" S10 (polyester film, manufactured by Toray Industries, Inc.) was roughened to a surface roughness Ra of 0.1 to 0.6 μm. "Gosenol®" AL-06 (partially saponified polyvinyl alcohol with a saponification degree of 91 to 94 mol%, manufactured by Mitsubishi Chemical Corporation) was applied to this roughened surface to a dry film thickness of 1 μm, and the film was dried at 100°C for 25 seconds to obtain a cover film.

[0079] (Example 1) (A) The polyvinyl alcohol derivative obtained in Production Example 1 was dissolved in a mixed solvent of 150 parts by mass of water and 100 parts by mass of ethanol, and then the other components shown in Table 1 were mixed to obtain a photosensitive resin composition solution. The obtained photosensitive resin composition solution was applied to a support having an easy-adhesion layer obtained in Production Example 2 to a dry film thickness of 800 μm, and dried at 40°C for 6 hours to obtain a laminate consisting of a photosensitive resin layer / support with an average thickness of 800 μm. A mixed solvent of water / ethanol = 50 / 50 (by weight ratio) was applied to the photosensitive resin layer of the obtained laminate, and the cover film obtained in Production Example 3 was pressed onto the surface to obtain a photosensitive resin printing plate original 1. The results of evaluation using the evaluation method described above are shown in Table 1.

[0080] (Examples 2-10) A photosensitive resin printing plate master was obtained in the same manner as in Example 1, except that the types and amounts of components (A) to (D) were changed as shown in Table 1. The results of evaluation using the evaluation method described above are shown in Table 1.

[0081] (Comparative Examples 1-4) A photosensitive resin printing plate master was obtained in the same manner as in Example 1, except that the types and amounts of components (A) to (D) were changed as shown in Table 2. The results of evaluation using the evaluation method described above are shown in Table 1.

[0082] [Table 1]

Claims

1. A photosensitive resin printing plate master having a photosensitive resin layer on a support containing polyvinyl alcohol and / or its derivative (A), a compound having an ethylenically double bond (B), a photopolymerization initiator (C), and a compound having a structure represented by the following general formula (1) (D). 【Chemistry 1】 (In the above general formula (1), R represents an alkyl group having 10 or more carbon atoms, and n represents an integer from 1 to 20.)

2. The photosensitive resin printing plate master according to claim 1, wherein the content of (D) in the photosensitive resin layer is 2 to 30 parts by mass per 100 parts by mass of (A).

3. A method for manufacturing a printing plate, comprising: an exposure step of irradiating the photosensitive resin layer of the photosensitive resin printing plate master according to claim 1 or 2 with ultraviolet light to photo-cure the exposed portion of the photosensitive resin layer; and a development step of removing the uncured portion of the photosensitive resin layer with a developing solution mainly composed of water.

4. A method for manufacturing a printed material, comprising a transfer step of transferring an active energy ray-curable ink to a substrate using a printing plate obtained by the manufacturing method described in claim 3, and an active energy ray irradiation step of irradiating the transferred active energy ray-curable ink with active energy rays.

Images