Laminate for producing water-developable flexographic printing original plates

Abstract

The present invention provides a water-developable laminate for producing a flexographic printing original plate, which is a laminate in which a functional resin layer including a photosensitive resin layer having strong surface adhesion is separately provided, and which allows the cover film to be properly peeled off from the photosensitive resin layer even when stored in an environment with large changes in temperature and humidity.The water-developable laminate for producing a flexographic printing original plate, which is formed by laminating a base film, a photosensitive resin layer, and a cover film in this order, is characterized in that a release layer is provided between the photosensitive resin layer and the cover film in contact with both, and that the release layer contains an addition type silicone polymer and a curing catalyst.

Description

[Technical field]

[0001] The present invention relates to a high-resolution water-developable laminate for producing a flexographic printing original plate, in which a base film, a photosensitive resin layer, and a cover film are laminated in this order, and which enables the cover film to be appropriately peeled off from the photosensitive resin layer. [Background technology]

[0002] A typical flexographic printing plate is composed of a laminate in which a base film, a photosensitive resin layer, a mask layer, and a cover film are laminated in this order, as shown in Figure 1. The cover film is intended to prevent the mask layer from becoming dirty or scratched during storage from when the flexographic printing plate is manufactured until it is actually used to create a printing plate. Therefore, when it is used, the cover film is removed, and as shown in Figure 2, a desired pattern is drawn on the mask layer with an infrared laser, then ultraviolet light is irradiated from the mask layer side to harden the photosensitive resin layer according to the pattern of the mask layer, and finally the plate is developed with a developer such as water to obtain a flexographic printing plate.

[0003] In this general method, a release layer (not shown) is provided between the cover film and the mask layer to properly remove the cover film. The material of the release layer is an amino resin (see Patent Document 1) or an acrylic resin (see Patent Document 2), which can form a uniform layer between the cover film and the mask layer.

[0004] On the other hand, in recent years, there has been an increasing demand for flexographic printing original plates with higher resolution, and the above-mentioned general flexographic printing original plates have limitations in the resolution of the mask layer, and improvements are being sought. In response to such demands, a method has been proposed in which the mask layer is separated from the photosensitive resin layer, the mask layer is provided on a polarizing film to form a separate laminate, and a pattern is drawn on the mask layer in this separate laminate, which is then laminated on the photosensitive resin layer (see Patent Document 3). Specifically, as shown in Figure 3, a laminate 1 in which a base film, a photosensitive resin layer, and a cover film are laminated in this order, and a laminate 2 in which a mask layer and a polarizing film are laminated in this order are prepared. As shown in Figure 4, a desired pattern is drawn on the mask layer of laminate 2 with a high-resolution laser. From the photosensitive resin layer of laminate 1 from which the cover film has been removed, laminate 2 is laminated and integrated with the side of the drawn mask layer facing the photosensitive resin layer. After that, ultraviolet light is irradiated from the polarizing film side of laminate 2 to harden the photosensitive resin layer according to the pattern of the drawn mask layer, and finally development is performed to obtain a flexographic printing plate.

[0005] In addition to the method of Patent Document 3 described above, a method is also known in which a mask layer separated from a photosensitive resin layer is formed with an image such as a high-resolution negative film, or a heat-sensitive mask layer on which an image is formed by laser ablation, or a method is also known in which another photosensitive resin layer having a hardness different from that of the resin of the photosensitive resin layer, another photosensitive resin layer having a photopolymerizable unsaturated group concentration or photoinitiator concentration different from that of the resin of the photosensitive resin layer, or another photosensitive resin layer having a surface energy different from that of the resin of the photosensitive resin layer is laminated on these mask layers. In the present invention, these mask layers and other photosensitive resin layers are collectively referred to as "functional resin layers".

[0006] In this method of separately providing a functional resin layer, unlike the general method, a cover film for protection during storage is provided on the photosensitive resin layer of the laminate 1. Basically, peeling of the cover film from the photosensitive resin layer of this laminate 1 poses almost no problem when stored in an environment with little change in temperature and humidity. Therefore, in the conventional method of separately providing a functional resin layer, a release layer was not provided.

[0007] However, since the photosensitive resin layer contains liquid components such as crosslinking monomers and low Tg polymers, the surface adhesion of the photosensitive resin layer tends to increase when the photosensitive resin layer is stored in an environment with frequent changes in temperature and humidity. In particular, in recent years, the demand for water-developable flexographic printing plates using water instead of organic solvents as a developer has been increasing due to increased consideration for the environment. However, when the photosensitive resin layer is made water-developable with high hydrophilicity to make the flexographic printing plate water-developable, the surface adhesion of the photosensitive resin layer tends to increase further. Therefore, in a laminate used for manufacturing a water-developable flexographic printing plate in a method of separately providing a functional resin layer, the photosensitive resin layer of the laminate 1 strongly adheres to the cover film during storage in an environment with frequent changes in temperature and humidity, and a problem occurs in which the cover film cannot be properly peeled off from the photosensitive resin layer. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5903854 [Patent Document 2] Patent No. 6135040 [Patent Document 3] Special Publication No. 2010-534345 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made to solve the problems of the conventional technology, and has an object to provide a water-developable laminate for producing a flexographic printing original plate in which the above-mentioned functional resin layer including the photosensitive resin layer having strong surface adhesion is separately provided, which allows the cover film to be appropriately peeled off from the photosensitive resin layer even when the laminate is stored in an environment with large changes in temperature and humidity. [Means for solving the problem]

[0010] In order to achieve this object, the present inventor first considered providing a release layer between the photosensitive resin layer and the cover film. Next, when this release layer was made of an amino resin (Patent Document 3) or an acrylic resin (Patent Document 4) that had been used as a release layer in the above general method, it was found that the water-developable photosensitive resin layer had too strong a surface adhesive force, and therefore the cover film could not be properly peeled off even if such a release layer was provided. Therefore, the present inventor used a release layer containing an addition type silicone polymer and a curing catalyst that could not be used in the general method, and found that the cover film could be properly peeled off even with a water-developable photosensitive resin layer, leading to the completion of the present invention.

[0011] That is, the present invention has been completed based on the above findings, and has the following features (1) to (7). (1) A water-developable laminate for producing a flexographic printing original plate, comprising a base film, a photosensitive resin layer, and a cover film laminated in this order, the laminate being characterized in that a release layer is provided between and in contact with the photosensitive resin layer and the cover film, and the release layer contains an addition type silicone polymer and a curing catalyst. (2) The laminate for producing a flexographic printing original plate according to (1), wherein the addition type silicone polymer contains an alkenyl group at its terminal and / or side chain. (3) The laminate for producing a flexographic printing original plate according to (1), wherein the curing catalyst is a hydrosilylation catalyst. (4) The laminate for producing a flexographic printing original plate according to any one of (1) to (3), wherein the surface roughness (Ra) of the surface of the release layer that comes into contact with the photosensitive resin layer is 0.01 to 0.2 μm. (5) The laminate for producing a flexographic printing plate according to any one of (1) to (3), characterized in that the peel strength when the cover film together with the release layer is pulled from the laminate for producing a flexographic printing plate at an angle of 90° at a speed of 1000 mm / min is 2.0 g / 20 mm to 50.0 g / 20 mm. (6) The laminate for producing a flexographic printing original plate according to any one of (1) to (3), wherein the photosensitive resin layer contains a conjugated diene polymer, a photopolymerizable unsaturated compound, and a photopolymerization initiator. (7) A method for producing a flexographic printing original plate, comprising peeling off a cover film together with a release layer from a laminate for producing a flexographic printing original plate according to any one of (1) to (3), and then directly laminating a resin layer surface of a functional resin layer on a photosensitive resin layer to produce a flexographic printing original plate. Effect of the Invention

[0012] The laminate for producing a flexographic printing original plate of the present invention has excellent releasability and storage stability of the release layer even when stored in an environment with large changes in temperature and humidity, and can appropriately peel the cover film from the photosensitive resin layer. Therefore, the laminate for producing a flexographic printing original plate of the present invention can be suitably used in combination with a functional resin layer for stably producing a water-developable flexographic printing original plate with high resolution. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 shows an example of the layer structure of a laminate constituting a flexographic printing plate precursor used in a general method. [Diagram 2] FIG. 2 shows an example process for producing a flexographic printing plate using the laminate of FIG. [Diagram 3] FIG. 3 shows an example of the layer structure of a laminate for producing a flexographic printing original plate, which is used in a method in which a functional resin layer is separately provided. [Figure 4] FIG. 4 shows an example process for making a flexographic printing plate using the laminate of FIG. [Diagram 5] FIG. 5 shows an example of the layer structure of the laminate for producing a flexographic printing original plate of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The laminate for producing a flexographic printing plate of the present invention has the same function as the laminate 1 (see Fig. 3) for producing a flexographic printing plate by the method of separately providing a functional resin layer described above, and specifically, as shown in the upper part of Fig. 5, in a laminate in which a base film, a photosensitive resin layer, and a cover film are laminated in this order, a release layer is provided between the photosensitive resin layer and the cover film in contact with both of them. Also, the release layer contains an addition type silicone polymer and a curing catalyst.

[0015] As the base film of the laminate of the present invention, a material having flexibility and excellent dimensional stability is preferable, and for example, a polyethylene terephthalate film, a polyethylene naphthalate film, a polybutylene terephthalate film, or a polycarbonate film can be used. Among these, a polyethylene terephthalate film having excellent dimensional stability and high viscoelasticity is particularly preferable. The thickness of the base film is preferably 50 to 350 μm, more preferably 100 to 350 μm, in view of mechanical properties, shape stability, or handling of the printing plate. If necessary, a known adhesive layer may be provided between the base film and the photosensitive resin layer to improve adhesion between them.

[0016] The photosensitive resin layer of the laminate of the present invention is not particularly limited as long as it is water-developable, and may contain, for example, (a) a conjugated diene polymer, (b) a photopolymerizable unsaturated compound, and (c) a photopolymerization initiator. In the present invention, since the development step is carried out with an aqueous developer, it is preferable that the photosensitive resin layer further contains (d) a hydrophilic compound. As the photosensitive resin composition containing the components (a) to (d), for example, the one described in JP-A-2005-148588 can be suitably used.

[0017] As the (a) conjugated diene polymer, a conjugated diene polymer obtained from a water-dispersed latex is preferred, and a conventionally known synthetic polymer compound used in a flexographic printing plate can be used. As the water-dispersed latex, it is preferred to contain one or more latexes selected from the group consisting of butadiene latex, acrylonitrile-butadiene latex, styrene-butadiene latex, and isoprene latex, and it is more preferred to contain both butadiene latex and acrylonitrile-butadiene latex from the viewpoint of water developability. When using a conjugated diene polymer obtained from a water-dispersed latex, it is preferred to use one that is intramolecularly crosslinked. In addition, it may be modified with (meth)acrylic, carboxy, silicone, fluorine, etc. as desired. In addition, a large number of various synthetic latexes and natural latexes are commercially available as water-dispersed latexes, and an appropriate one can be selected from them.

[0018] As the (b) photopolymerizable unsaturated compound, any of the conventionally known compounds used in flexographic printing original plates can be used, but it is preferable that the compound contains a photopolymerizable monomer such as a (meth)acrylate having a number average molecular weight of 100 or more and 600 or less, and further preferably contains a photopolymerizable oligomer such as a (meth)acrylate having a number average molecular weight of more than 600 and 20,000 or less. The photopolymerizable oligomer is not particularly limited as long as it has a number average molecular weight in the range of more than 600 and 20,000 or less, and examples of the photopolymerizable oligomer include butadiene oligomers or isoprene oligomers to which a (meth)acrylate group has been added, and urethane (meth)acrylates.

[0019] (c) The photopolymerization initiator preferably has a function of generating radicals by self-decomposition or hydrogen abstraction by light absorption. Examples of such photopolymerization initiators include benzoin alkyl ethers, benzophenones, anthraquinones, benzils, acetophenones, and diacetyls. Examples include benzophenone, chlorobenzophenone, benzoin, acetophenone, benzil, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzil dimethyl ketal, benzil diethyl ketal, benzil diisopropyl ketal, anthraquinone, 2-ethylanthraquinone, 2-methylanthraquinone, 2-allylanthraquinone, 2-chloroanthraquinone, thioxanthone, 2-chlorothioxanthone, and 1-hydroxycyclohexan-1-ylphenyl ketone. The photopolymerization initiator is preferably a compound consisting of two types of compounds, a benzyl alkyl ketal type and a benzophenone type, in order to use the light energy of post-exposure and exposure by a germicidal lamp without waste.

[0020] (d) The hydrophilic compound is used to improve water developability, and is a compound having a hydrophilic group in the molecule, such as carboxylic acid, carboxylate, sulfonic acid, sulfonate, hydroxyl group, amino group, phosphoric acid group, ethylene oxide, or propylene oxide, and is water-soluble or water-dispersible. The hydrophilic compound may be a low molecular weight compound, an oligomer, a polymeric compound, or a hydrophilic polymer. Specific examples of the hydrophilic compound include polyhydric alcohol, polycarboxylic acid, ester compound of polycarboxylic acid, acrylic polymer, polyalkylene glycol modified polymer, urethane polymer, polyamide polymer, and polyester polymer. When using a hydrophilic copolymer, it is preferable to use internally crosslinked polymer particles containing units derived from a hydrophilic unsaturated monomer. Examples of these polymer particles include water-dispersed latex, which is obtained by emulsion polymerization using a hydrophilic unsaturated monomer and, if necessary, other monomers that can be copolymerized with the monomer, and disperses the polymer particles in water as dispersoids.

[0021] In addition to the above-mentioned components (a) to (d), the photosensitive resin layer of the laminate of the present invention may contain other components, such as plasticizers, ultraviolet absorbers, thermal polymerization inhibitors (stabilizers), surface tension adjusters, thermoplastic resin elastomers, solid rubbers, dyes, pigments, defoamers, and anti-aggregation agents, as appropriate, for the purpose of improving various properties, provided that the effects of the present invention are not impaired.

[0022] The cover film of the laminate of the present invention is preferably made of a material that is flexible but has excellent dimensional stability, and examples of such materials include thermoplastic resin supports such as polyethylene terephthalate film, polyethylene naphthalate film, and polybutylene terephthalate film. Among these, polyethylene terephthalate film, which has excellent dimensional stability and high viscoelasticity, is particularly preferred. The thickness of the cover film is preferably 50 to 350 μm, more preferably 70 to 250 μm, in view of mechanical properties, shape stability, or handling during printing plate making.

[0023] The release layer of the laminate of the present invention contains an addition type silicone polymer and a curing catalyst as a curing agent. The addition type silicone polymer is preferably a silicone polymer having an alkenyl group at the end and / or side chain. Examples of the alkenyl group include vinyl, allyl, propenyl, hexenyl, octenyl, and decenyl groups, and from the viewpoint of curability, vinyl, allyl, and hexenyl groups are preferred. Commercially available examples of addition type silicone polymers include KS-3650, KS-774, KS-775, KS-778, KS-779H, KS-843, KS-847, KS-847H, KS-847T, KS-838, KS-856, X-62-2422, X-62-2461, X62-2829, X-62-1387, X-62-5039, X-62-5040, KNS-3051, X-62-1496, KNS320A, KNS316, and X-62-1 574A / B, X-62-7052, X-62-7028A / B, X-62-7619, X-62-7213, and Dow Corning Toray Co., Ltd.'s SD7220, SD7226, SD7223, SD7292, SD7333, SRX211, SRX357, SRX345, LTC750A, LTC760A, LTC851, LTC759, LTC755, LTC761, LTC856, LTC310, LTC303E, LTC300B, and LTC350G.

[0024] The addition type silicone polymer having an alkenyl group may also contain a hydrosilyl group (SiH) in the molecule. Commercially available examples include KS-3650, KS-843, KS-847, KS-847H, KS-847T, X62-2829, and KS838 manufactured by Shin-Etsu Chemical Co., Ltd., and SD7333, SRX357, SRX345, LTC310, LTC303E, LTC300B, LTC350G, LTC750A, LTC851, LTC759, LTC755, LTC761, and LTC856 manufactured by Dow Corning Toray Co., Ltd.

[0025] These addition type silicone polymers may be used alone or in combination of two or more. In addition, addition type silicone polymers not having alkenyl groups may be contained within a range that does not deteriorate the performance. In this case, a polymer having a high molecular weight that is less likely to bleed out is preferable.

[0026] Since the release layer contains an addition type silicone polymer, it is preferable to contain a polyorganosiloxane compound (crosslinking agent) having a hydrosilyl group (SiH). By containing such a polyorganosiloxane compound (crosslinking agent), the addition reaction is easily promoted, and as a result, excellent releasability can be obtained. A specific example of the compound is 1,3,5,7-tetramethylcyclotetrasiloxane.

[0027] The curing catalyst forms a crosslinked structure of the silicone polymer and has the effect of suppressing aggregation of the silicone polymer on the surface of the release layer or in the release layer. As the curing catalyst, a hydrosilylation catalyst is preferable. The hydrosilylation catalyst is not particularly limited as long as it has catalytic activity for the hydrosilylation reaction, and examples thereof include platinum alone, solid platinum supported on a carrier such as alumina, silica, or carbon black, chloroplatinic acid, complexes of chloroplatinic acid with alcohols, aldehydes, ketones, etc., platinum-olefin complexes, platinum-vinylsiloxane complexes, platinum-phosphine complexes, platinum-phosphite complexes, etc. Examples of catalysts other than platinum compounds include RhCl(PPh)3, RhCl3, RhAl2O3, RuCl3, IrCl3, FeCl3, AlCl3, PdCl2·2H2O, NiCl2, TiCl4, etc. Among them, in terms of the peeling effect, platinum catalysts such as platinum alone, solid platinum supported on alumina, silica, or carbon black carriers, platinum-olefin complexes, platinum-vinylsiloxane complexes, platinum-phosphine complexes, and platinum-phosphite complexes are preferred. More preferred are platinum complexes such as platinum-vinylsiloxane complexes and platinum-olefin complexes. These catalysts may be used alone or in combination of two or more.

[0028] Specific platinum catalysts may be produced by known methods or may be purchased as commercially available products. Platinum-vinylsiloxane complexes can be produced by standard methods such as those disclosed in Japanese Patent Publication No. 47-23679 and Japanese Patent Laid-Open No. 11-128748. Commercially available products include PL-3 and CAT-PL-50T manufactured by Shin-Etsu Chemical Co., Ltd., and SRX212 manufactured by Dow Toray Co., Ltd.

[0029] The amount of the curing catalyst in the release layer is preferably 0.01 to 5.0 parts by mass, more preferably 0.015 to 4.0 parts by mass, and even more preferably 0.02 to 3.0 parts by mass, relative to 100 parts by mass of the addition type silicone polymer. If the amount of the curing catalyst is small, the curing reaction does not proceed sufficiently, and the amount of remaining Si-H groups increases, resulting in a high peeling force. In addition, since unreacted organopolysiloxane exists and becomes a migration component, there is a risk that the unreacted organopolysiloxane will migrate to the photosensitive resin layer to which the functional resin is bonded, causing a decrease in adhesive strength. Furthermore, when a functional resin layer is provided on a photosensitive resin layer, the irradiated ultraviolet light will scatter, causing a decrease in image reproducibility, or the functional resin layer will peel off due to poor adhesion between the photosensitive resin layer and the functional resin layer.

[0030] The release layer may contain a resin other than the addition type silicone polymer as long as it does not impair the peelability. For example, it may contain a thermosetting resin such as an acrylic resin, a photocurable resin having a photopolymerizable unsaturated group, a phenolic resin, an epoxy resin, or a melamine resin. By containing a resin other than the addition type silicone polymer, it is possible to easily control the adhesion to the cover film and the peel strength of the release layer.

[0031] In addition to the addition type silicone polymer and the curing catalyst, the release layer may contain a release force adjuster such as a silane coupling agent, a crosslinking agent, a tackifier, a plasticizer, or a softener for the purpose of adjusting the peel strength. Furthermore, other additives may be added to the release layer as long as they do not affect the peelability. For example, deterioration inhibitors, fillers, colorants, antioxidants, surfactants, antistatic agents, etc. may be added.

[0032] The release layer can be produced by applying a coating liquid for forming a release layer onto a cover film. As a coating method, a conventionally known method such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating, etc. can be adopted. The coating liquid for forming a release layer can be prepared, for example, by mixing an addition type silicone polymer and a curing catalyst with a solvent. As the solvent, ketones (e.g., methyl ethyl ketone), aromatic compounds (e.g., toluene), etc. can be used. These can be used alone or in a mixture of two or more kinds.

[0033] The thickness of the release layer is preferably 0.01 μm to 2 μm, more preferably 0.03 μm to 1.5 μm, and further preferably 0.05 μm to 1 μm. If the thickness is too small, the peel force may not be sufficiently adjusted. On the other hand, if the thickness is too large, streaks are likely to occur during production.

[0034] The surface roughness (Ra) of the surface of the release layer in contact with the photosensitive resin layer is preferably 0.01 to 0.2 μm. By setting the surface roughness in this range, the surface roughness of the photosensitive resin layer surface can be reduced. As a result, air bubbles are less likely to be mixed in and wrinkles are less likely to occur when the release layer is in close contact with the functional resin layer, and defects can be reduced on the lamination surface with the functional resin layer. The surface roughness of the surface of the release layer in contact with the photosensitive resin layer of the present invention refers to the surface roughness of the release layer in contact with the photosensitive resin layer.

[0035] The laminate of the present invention preferably has a peel strength of 2.0 g / 20 mm to 50.0 g / 20 mm when the cover film and the release layer are pulled at 90° at a speed of 1000 mm / min. More preferably, the peel strength is 3.0 g / 20 mm to 20.0 g / 20 mm. By setting the peel strength within this range, the release layer can be appropriately and uniformly peeled off from the photosensitive resin layer.

[0036] Moreover, it is preferable that the temperature dependency of the measured value of the peel strength (measured value at 10°C - measured value at 30°C) is small. By reducing the temperature dependency of the measured value, it is possible to reduce the variation of the peel strength due to temperature. Specifically, the difference between the measured values ​​of the peel strength at temperatures of 10°C and 30°C (measured value at 10°C - measured value at 30°C) is preferably 30.0 grams / 20 mm or less, and more preferably 10.0 grams / 20 mm or less.

[0037] Next, a method for producing a flexographic printing plate from the laminate of the present invention will be described. The laminate of the present invention shown in the upper part of FIG. 5 can be efficiently produced to produce a flexographic printing plate used to produce a printing plate by directly laminating the resin layer surface of the functional resin layer shown in the lower part of FIG. 5 on the photosensitive resin layer after peeling off and removing the cover film together with the release layer. As the functional resin layer, a conventionally known one in this field can be used, and examples thereof include a mask layer on which an image such as a high-resolution negative film is formed, a heat-sensitive mask layer on which an image is formed by laser ablation, a different photosensitive resin layer having a hardness different from that of the resin of the photosensitive resin layer, a different photosensitive resin layer having a photopolymerizable unsaturated group concentration or a photoinitiator concentration different from that of the resin of the photosensitive resin layer, and a different photosensitive resin layer having a surface energy different from that of the resin of the photosensitive resin layer. The functional resin layer may be laminated on a support film. The support film also serves as an oxygen barrier layer. The effect of the present invention is easily obtained, particularly when a high-resolution negative film is used as the functional resin layer. In the present invention, the negative film is a mask layer on which an image is formed to be laminated on a photosensitive resin layer, and usually refers to a mask layer provided on a support film.

[0038] In the present invention, a high-resolution negative film refers to one that can reproduce 1% to 95% of 200-line halftone dots. As a high-resolution negative film, a negative film in which a mask image is formed by a laser is preferable. As a negative film in which a mask image is formed by a laser, a film in which the ultraviolet light transmittance of the heat-sensitive mask layer is partially improved by the change in color development or optical transparency accompanying heating by a laser is preferable because finer highlight halftone dots can be formed. As described above, the support film in the negative film also plays a role as an oxygen barrier layer to reduce the influence of oxygen. In addition, in order to reduce the scattering of ultraviolet light by the support film, a polarizing film may be used as the support film, or a dye having ultraviolet light absorbency or ultraviolet light absorption may be contained in the support film. The high-resolution negative film can be a commercially available product or can be manufactured by a known method. As a commercially available resolution negative film, DITR4401 film manufactured by Kodak Corporation and the like can be mentioned. Known high-resolution negative films include a mask layer in which the refractive index of the support film is controlled (Japanese Patent No. 5,368,432), a heat-sensitive mask layer in which a barrier layer containing an infrared absorbing compound is provided on a support film (Japanese Patent No. 6,449,854), and a mask layer in which the support of the mask layer can be peeled off and removed (Japanese Patent No. 4,971,311).

[0039] Specific printing original plates obtained from the laminate of the present invention include a flexographic printing original plate having a mask layer on which an image such as a high-resolution negative film is formed on a photosensitive resin layer, a heat-sensitive mask layer on which an image is formed by laser ablation, and a flexographic printing original plate having another photosensitive resin layer on a photosensitive resin layer having a different hardness from the resin of the photosensitive resin layer, another photosensitive resin layer having a different photopolymerizable unsaturated group concentration or photoinitiator concentration from the resin of the photosensitive resin layer, or another photosensitive resin layer having a different surface energy from the resin of the photosensitive resin layer. Specifically, the laminate of the present invention is produced by directly laminating the resin layer surface of the functional resin layer on the photosensitive resin layer to produce a flexographic printing original plate, and when the functional resin layer is another photosensitive resin layer, a mask layer is provided thereafter, and the laminate can be used to produce a printing plate through platemaking processes such as normal ultraviolet exposure, development, drying, and post-exposure. The functional resin layer may be removed in the platemaking process, or may remain on the photosensitive resin layer as a resin layer without being removed. EXAMPLES

[0040] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0041] [Example 1] Preparation of release film 99 parts by mass of vinyl group-containing addition type silicone polymer (KS-847T: Shin-Etsu Chemical Co., Ltd.) and 1 part by mass of curing catalyst (CAT-PL-50T: Shin-Etsu Chemical Co., Ltd.) were diluted with a methyl ethyl ketone / toluene mixed solvent (mixed mass ratio 1:1) to prepare a release layer coating solution with a concentration of 2% by mass. Next, the coating solution was applied to a 100 μm thick polyethylene terephthalate film (Toyobo Co., Ltd.) that would become a cover film using a wire bar so that the coating layer thickness after drying would be 0.1 μm, and the coating was dried and cured at 120° C. for 40 seconds to obtain a release film consisting of a release layer and a cover film.

[0042] Preparation of photosensitive resin composition (a) 39 parts by mass of butadiene latex (Nipol LX111NF, non-volatile content 55% by mass, manufactured by Zeon Corporation) as a conjugated diene polymer obtained from a water-dispersed latex, carboxy-modified acrylonitrile-butadiene latex (Nipol SX1503, non-volatile content 42% by mass, manufactured by Nippon Zeon Co., Ltd.) 6 parts by mass, (b) oligobutadiene acrylate (ABU-4, manufactured by Kyoeisha Chemical Co., Ltd.) as a photopolymerizable unsaturated compound 17 parts by mass, trimethylolpropane trimethacrylate (Light Ester TMP, manufactured by Kyoeisha Chemical Co., Ltd.) 6.4 parts by mass, the above-mentioned metal chloride of diene polymer having a carboxyl group at the end 25 parts by mass, (c) photopolymerization initiator (Irgacure 651) 1 part by mass, (d) butadiene oligomer (LBR-352, manufactured by Kuraray Co., Ltd.) 5.5 parts by mass, and heat stabilizer (4-methoxyphenol) 0.1 parts by mass were mixed in a container to prepare a dope. The dope was put into a pressure kneader, and tetrahydrofuran and water were removed under reduced pressure at 80 ° C. to obtain a photosensitive resin composition.

[0043] Preparation of laminates for flexographic printing plate manufacturing The above photosensitive resin composition was placed on a polyethylene terephthalate base film (support) (Toyobo Co., Ltd., E5000, thickness 125 μm) coated with a copolymer polyester adhesive to form a photosensitive resin layer. Next, the above release film was placed on top of it with the release layer facing the photosensitive resin layer. They were pressed together at 100° C. using a heat press machine to obtain a laminate for manufacturing a flexographic printing original plate. The total thickness of this laminate was 1.14 mm.

[0044] Preparation of functional resin layer As a functional resin layer, a high-resolution negative film (a mask layer in which the transmittance of ultraviolet light is partially improved by changes in color development or optical transparency due to heating with a laser) was prepared. Specifically, a negative film with 200 lines of halftone dots 1% to 95%, a minimum independent point diameter of 100 μm, a minimum convex character of 1 point, a minimum hollow character of 1 point, and a solid image was prepared on a 100 μm thick support film from DITR4401 film (Kodak), a high-resolution negative film compatible with a printing resolution of up to 200 lines, using a TRENDSETTER imager (Kodak) capable of SQUAREspot thermal imaging using an 830 nm infrared laser diode.

[0045] Preparation of flexographic printing plates and flexographic printing plates The cover film was peeled off together with the release layer from the laminate for manufacturing a flexographic printing original plate, and the resin layer surface (the surface opposite to the support film) of the functional resin layer was laminated onto the photosensitive resin layer of the laminate for manufacturing a flexographic printing original plate to obtain a flexographic printing original plate. The obtained printing original plate was made into a printing plate by the following method. First, the printing plate was exposed to light from the back side of the support (polyethylene terephthalate base film) for 10 seconds. This was followed by a main exposure for 7 minutes. This was then developed for 8 minutes using an A&V Corporation developer (Stuck System, 1% laundry soap aqueous solution, 40°C), and water droplets on the plate surface were removed with a water stripper. This was then dried for 10 minutes in a 60°C dryer. This was followed by a post-exposure for 7 minutes, and finally irradiation with a germicidal lamp for 5 minutes to obtain a flexographic printing plate.

[0046] [Example 2] In preparing the coating solution for the release layer, a release film was formed in the same manner as in Example 1, except that the vinyl group-containing addition type silicone polymer (KS-847T: manufactured by Shin-Etsu Chemical Co., Ltd.) was replaced with a 30 mass% toluene solution of a vinyl group-containing addition type silicone polymer (KS-774 manufactured by Shin-Etsu Chemical Co., Ltd.). Next, a laminate for manufacturing a flexographic printing original plate was manufactured in the same manner as in Example 1 using the obtained release film.

[0047] [Example 3] A release film was formed in the same manner as in Example 1, except that in the preparation of the coating liquid for the release layer, a hexenyl group-containing addition type silicone polymer (LTC750A, manufactured by Toray Dow Corning Co., Ltd.) was used instead of a vinyl group-containing addition type silicone polymer (KS-847T, manufactured by Shin-Etsu Chemical Co., Ltd.). Next, a laminate for manufacturing a flexographic printing original plate was manufactured in the same manner as in Example 1, using the obtained release film.

[0048] [Example 4] In the preparation of the coating solution for the release layer, a release film was formed in the same manner as in Example 1, except that the curing catalyst (CAT-PL-50T: manufactured by Shin-Etsu Chemical) was changed to a curing catalyst (PL-3: manufactured by Shin-Etsu Chemical). Next, a laminate for manufacturing a flexographic printing original plate was manufactured in the same manner as in Example 1 using the obtained release film.

[0049] [Example 5] A release film was formed in the same manner as in Example 1, except that in the preparation of the coating solution for the release layer, the curing catalyst (CAT-PL-50T: manufactured by Shin-Etsu Chemical) was changed to a curing catalyst (SRX212: manufactured by Dow-Toray Co., Ltd.). Next, a laminate for manufacturing a flexographic printing original plate was manufactured in the same manner as in Example 1, using the obtained release film.

[0050] [Example 6] A release film was formed in the same manner as in Example 1, except that in the preparation of the coating liquid for the release layer, a crosslinking agent (1,3,5,7-tetramethylcyclotetrasiloxane) was blended in the blending ratio shown in Table 1 in addition to the addition type silicone polymer and the curing catalyst. Next, a laminate for manufacturing a flexographic printing original plate was manufactured in the same manner as in Example 1 using the obtained release film.

[0051] [Example 7] In preparing the coating solution for the release layer, the vinyl group-containing addition type silicone polymer (KS-847T: manufactured by Shin-Etsu Chemical) was changed to a mixture of the vinyl group-containing addition type silicone polymer (KS-847T: manufactured by Shin-Etsu Chemical) and the hexenyl group-containing addition type silicone polymer (LTC750A manufactured by Dow Corning Toray Co., Ltd.) in a solid content mass ratio of 70 / 30, except that the release film was produced in the same manner as in Example 1. Next, a laminate for manufacturing a flexographic printing original plate was produced in the same manner as in Example 1 using the obtained release film.

[0052] [Example 8] A release film was formed in the same manner as in Example 1, except that the blending ratio of the curing catalyst was reduced as shown in Table 1. Next, a laminate for manufacturing a flexographic printing original plate was produced in the same manner as in Example 1 using the obtained release film.

[0053] [Comparative Example 1] A laminate for producing a flexographic printing original plate was produced in the same manner as in Example 1, except that a cover film without a release layer was used.

[0054] [Comparative Example 2] In preparing the coating solution for the release layer, a release film was formed in the same manner as in Example 1, except that the vinyl group-containing addition type silicone resin (KS-847T: manufactured by Shin-Etsu Chemical) was replaced with a non-addition type silicone polymer (X-52-8046: manufactured by Shin-Etsu Chemical). Using the obtained release film, a laminate for manufacturing a flexographic printing original plate was manufactured in the same manner as in Example 1.

[0055] [Comparative Example 3] A release film containing an amino resin was produced according to the method for producing a release force adjusting layer described in Japanese Patent No. 5903854. Next, a laminate for producing a flexographic printing original plate was produced in the same manner as in Example 1 using the obtained release film.

[0056] [Comparative Example 4] An acrylic resin release film was produced according to the method for producing a peel force adjusting layer described in Japanese Patent No. 6135040. Next, a laminate for producing a flexographic printing original plate was produced in the same manner as in Example 1 using the obtained release film.

[0057] [Comparative Example 5] A release film was formed in the same manner as in Example 1, except that a curing catalyst (CAT-PL-50T: manufactured by Shin-Etsu Chemical Co., Ltd.) was not added to the coating liquid for the release layer in Example 1. Next, a laminate for manufacturing a flexographic printing original plate was manufactured in the same manner as in Example 1 using the obtained release film.

[0058] [Reference example 1] The photosensitive resin layer used was of a type that could not be developed with water but could be developed with a solvent. First, 100 parts by mass of a block copolymer (Tufprene 912, manufactured by Asahi Kasei Corporation), 10 parts by mass of liquid polybutadiene (NISSO-PB-B-1000, manufactured by Nippon Soda Co., Ltd.), and 2 parts by mass of 2,6-di-t-butyl-p-cresol were kneaded at 170°C using a kneader mixer. The kneading temperature was then lowered to 130°C, and 10 parts by mass of 1,6-hexanediol dimethacrylate, 0.01 parts by mass of methylhydroquinone, and 1 part by mass of a photopolymerization initiator (Irgacure 651) were added and kneaded to obtain a photosensitive resin composition of the type that can be developed using a solvent. The above photosensitive resin composition was placed on a polyethylene terephthalate base film (Toyobo Co., Ltd., E5000, thickness 125 μm) coated with a copolymer polyester adhesive to form a photosensitive resin layer. Next, a film without a release coating layer (Toyobo Co., Ltd., E5000, thickness 100 μm) was placed on top of the photosensitive resin composition. These were pressed at 100° C. using a heat press machine to obtain a laminate for manufacturing a flexographic printing original plate. The total thickness of this laminate was 1.14 mm. The cover film was peeled off from the obtained laminate for producing a flexographic printing original plate, and the resin layer surface of the same functional resin layer as in Example 1 was laminated onto the photosensitive resin layer of the laminate for producing a flexographic printing original plate to obtain a flexographic printing original plate. The obtained printing original plate was made into a printing plate by the following method. First, the printing plate was exposed to light from the polyester support side for 10 seconds. Then, the main exposure was performed for 7 minutes. After that, the plate was developed for 8 minutes using a developing machine (Stuck System, using mineral spirits as the developing solution) manufactured by A&V Corporation. Then, the plate was dried for 120 minutes in a dryer at 60°C. Then, the plate was exposed to light for 7 minutes, and finally, the plate was irradiated with a germicidal lamp for 5 minutes to obtain a flexographic printing plate.

[0059] The laminates and printing plates of the above-mentioned Examples, Comparative Examples, and Reference Examples were evaluated for the following characteristics (1) to (6). The evaluation methods were as follows.

[0060] (1) Cover film peel strength (10℃, 30℃) The laminate for manufacturing flexographic printing original plates prepared as test pieces was cut to 120 mm x 20 mm, the edge of the cover film was peeled off with fingertips, and the piece was set in a peel tester and pulled at 90° at a speed of 10,000 mm / min, and the peel strength (grams / 20 mm) was measured. The measurements were carried out in an environment of 10° C. or 30° C. The peel strength was evaluated by the following method. ◎: Peel strength is within the range of 3.0 g / 20 mm or more and 20.0 g / 20 mm or less. ○: The peel strength is outside the above range of ◎, but is within the range of 2.0 g / 20 mm or more and 50.0 g / 20 mm or less. ×: The peel strength is outside the range of either ◎ or ○.

[0061] (2) Temperature dependence of peel strength (measured at 10°C - measured at 30°C) To evaluate the temperature dependency of the peel strength of the release layer, the peel strength was measured at temperatures of 10°C and 30°C, and the difference between these measured values ​​was evaluated. The smaller the difference in the peel strength measurements (measured value at 10°C - measured value at 30°C), the smaller the temperature dependency of the peel strength. The evaluation was performed by the following method. ◎: The difference in peel strength measurements is 10 grams / 20 mm or less ○: When the difference in the peel strength measurement is more than 10g / 20mm and less than 20g / 20mm ×: When the difference in peel strength measurement exceeds 20 grams / 20 mm

[0062] (3) Storage stability of peel strength (3 months); The obtained laminate was stored at 30°C and 80% RH for 3 months, and then the cover film peel strength of the laminate was measured at 10°C in the same manner as in (1) Cover film peel strength (10°C, 30°C) to determine the peel strength.

[0063] (4) Bleed out The obtained laminate was stored separately for one month in each environment of 20°C, 65% RH and 30°C, 80% RH, and then the cover film was peeled off to visually judge whether the resin bleeds out from the release layer. Depending on the presence or absence of bleeding out, the following evaluation was made. ○: No bleed out ×: Bleed out

[0064] (5) Surface roughness of release layer (Ra) The surface roughness (Ra) of the release layer is the surface roughness (Ra) of the release layer surface of the release film. The measurement was performed by a confocal method using a confocal laser microscope. Specifically, a confocal laser microscope VK9510 manufactured by Keyence Corporation was used as the confocal laser microscope. The magnification of the objective lens was 50 times. A sample having a size of 10 cm length x 10 cm width was cut out from the release layer, and the sample was placed on the measurement stage of the confocal laser microscope, and the surface roughness (Ra) was measured at a total of 20 points while moving the sample vertically and / or horizontally by about 5 mm each time. The average value of the measured values ​​of the surface roughness (Ra) was taken as the surface roughness (Ra) of the release layer.

[0065] (6) Image reproducibility of printing plate The obtained laminate was stored separately for one month in each of the environments of 20°C, 65% RH and 30°C, 80% RH, and then flexographic printing original plates were prepared as described above, and the image reproducibility was evaluated using each of the obtained flexographic printing original plates. The case where there was no uneven adhesion (ultraviolet light leakage) was marked with an ◯, the case where there was uneven adhesion in some parts was marked with a △, and the case where there was uneven adhesion over the entire surface was marked with an ×.

[0066] Table 1 shows the details and evaluation results of the laminates of the examples, comparative examples, and reference examples.

[0067] [Table 1]

[0068] As can be seen from Table 1, the laminates of Examples 1 to 8, which satisfy the requirements of the present invention, all have cover film peel strengths within an appropriate range, and the difference in peel strength due to temperature (measured at 10°C - measured at 30°C) is small (i.e., temperature dependency is small). Furthermore, even after storage at 30°C for three months, there is little change in the cover film peel strength, and the storage stability is also excellent. Therefore, the laminates of Examples 1 to 8 can easily laminate a functional resin layer without being affected by seasonal changes, and a high-quality printing master plate can be obtained, and the obtained printing plate has excellent image reproducibility.

[0069] In contrast, in Comparative Example 1, the cover film could not be peeled off because there was no release layer. In Comparative Example 2, the release layer did not contain an addition type silicone polymer, so the peel strength could not be optimized and bleeding out could not be suppressed. As a result, the image reproducibility of the printing plate was poor and it was not usable as a printing plate. In Comparative Example 3, which used a release layer containing an amino resin, and Comparative Example 4, which used a release layer containing an acrylic resin, the peel strength of the cover film was not within the appropriate range, and it was difficult to peel off the cover film, especially at a low temperature of 10°C. In Comparative Example 5, the release coating composition did not have a curing catalyst, so the peel strength could not be optimized and bleeding out could not be suppressed. [Industrial Applicability]

[0070] The laminate for producing a flexographic printing original plate of the present invention can achieve excellent peelability of the cover film even when stored in an environment with changes in temperature and humidity, and therefore can provide a water-developable flexographic printing original plate that is free from abnormalities such as migration of silicone polymer that causes deterioration of quality on the surface of the photosensitive resin layer. Therefore, the present invention is extremely useful in the industry in which high-resolution water-developable flexographic printing plates are required.

Claims

1. A water-developable laminate for producing a flexographic printing original plate, the laminate being formed by laminating a base film, a photosensitive resin layer, and a cover film in that order, the laminate being characterized in that a release layer is provided between the photosensitive resin layer and the cover film in contact with both of them, and the release layer contains an addition type silicone polymer and a curing catalyst.

2. 2. The laminate for producing a flexographic printing original plate according to claim 1, wherein the addition type silicone polymer contains an alkenyl group at its terminal and / or at its side chain.

3. 2. The laminate for producing a flexographic printing original plate according to claim 1, wherein the curing catalyst is a hydrosilylation catalyst.

4. The laminate for producing a flexographic printing original plate according to any one of claims 1 to 3, characterized in that the surface roughness (Ra) of the surface of the release layer that comes into contact with the photosensitive resin layer is 0.01 to 0.2 µm.

5. The laminate for producing a flexographic printing original plate according to any one of claims 1 to 3, characterized in that the peel strength when the cover film together with the release layer is pulled from the laminate for producing a flexographic printing original plate at an angle of 90° at a speed of 1000 mm / min is 2.0 g / 20 mm to 50.0 g / 20 mm.

6. The laminate for producing a flexographic printing original plate according to any one of claims 1 to 3, characterized in that the photosensitive resin layer contains (a) a conjugated diene-based polymer, (b) a photopolymerizable unsaturated compound, and (c) a photopolymerization initiator.

7. A method for producing a flexographic printing original plate, comprising the steps of: peeling off the cover film together with the release layer from the laminate for producing a flexographic printing original plate according to any one of claims 1 to 3; and then directly laminating a resin layer surface of a functional resin layer on the photosensitive resin layer to produce a flexographic printing original plate.

Images