JP2014191132A - Production method of printing plate for relief printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing plate in which minute protrusions having a large relief depth are stably reproduced.SOLUTION: A production method of a printing plate for relief printing is provided, which is applied to a photosensitive printing plate precursor having at least a support body, a photosensitive resin layer (A) and a heat-sensitive mask layer (C) in this order, and which comprises patterning the heat-sensitive mask layer (C) by use of an IR laser, and then applying a diffusion film (F) having a light-diffusion angle of 40° or larger on the photosensitive printing plate precursor, exposing and developing the plate. Thereby, high image reproducibility with a stable shape can be obtained even in a platemaking process using a plate having an opaque substrate or an exposure machine having a point light source.

Description

  The present invention relates to a method for producing a photosensitive printing plate having a specific uneven shape.

  The use of a photosensitive resin composition for a photosensitive printing plate precursor is generally performed and has become mainstream in each field of relief printing, planographic printing, and intaglio printing.

  Conventionally, in letterpress printing, the so-called letter press printing method, which uses a high-hardness printing plate and high-viscosity UV ink for printing that requires high-precision images, such as label printing, is applied while applying high printing pressure. Was heavily used. In recent years, with the improvement in performance of flexographic printing plates, a type of letterpress printing method, UV curing has a lower viscosity than letter press printing even for printing that requires high-precision images due to the advantage of high-speed printing. The number of cases where flexographic printing using low-pressure inks and low printing pressure is employed is increasing. A flexographic printing plate generally has a printing plate hardness of 50 to 90 ° in terms of durometer, which is lower than that of a letter press plate. On the other hand, a plate thickness is thicker than that of a letter press plate and is 1.14 mm thick. In many cases, it is well over 1 mm, including 70 mm thickness. As for the image reproducibility of a printing plate, it is not uncommon that a thin line having a width of 50 μm or less is required for, for example, a line.

  In many photosensitive printing plate precursors, a photosensitive resin layer that is cured by active light such as ultraviolet light is formed as a relief layer on a transparent substrate having dimensional stability such as a polyester film. The so-called analog version is selectively cured using a predetermined negative film for image formation (main exposure step). On the other hand, in the so-called CTP (Computer To Plate) plate, a thermal mask layer that plays a role of blocking actinic rays for curing is formed in advance on the relief layer. This is removed to form an image, and then the relief layer is cured with actinic rays (this is called the main exposure step). The person skilled in the art will compare the incident angle of the ultraviolet light in the main exposure so as to reproduce the minute and sharp convex part as much as possible and the concave part with sufficient depth in order to obtain a high-quality print with high resolution. In many cases, an exposure light source (called a point light source) having only one light source that is nearly vertical is used. However, in the case of making a plate with a thick relief layer such as a flexographic printing plate, there is a problem that fine convex portions such as fine lines and independent points to be formed collapse or disappear in the development process. Cheap. Especially in the above-mentioned CTP plate, since the thermal mask layer is arranged in advance, it is not necessary to make a negative film adhere to the plate surface under reduced pressure using a soft vinyl chloride sheet or the like, and main exposure in the atmosphere is possible. The oxygen on the surface of the plate moderately inhibits curing, so it also has the advantage that the depth of the recesses is less likely to be shallow, but the relief of the projections maintains a sharp shape, making it possible to reproduce fine projections more Have difficulty. In order to suppress this, first, the entire surface of the plate is irradiated with actinic rays from the substrate side (referred to as a back exposure process), and the relief layer is cured to a certain thickness on the substrate side (this is referred to as a floor layer). ) After that, by carrying out main exposure, the base of the convex part after development becomes a shape integrated with the floor layer, and a method in which even a small convex part tends to remain on the printing plate without damage is generally known. .

  However, the above-described method is a case where the substrate is transparent and has a layer structure that allows the back exposure, and the back exposure cannot be performed when an opaque substrate such as steel is provided. In addition, when the back exposure process is not carried out, and the development process after the main exposure is intentionally terminated during development, the part corresponding to the floor layer is intentionally left. Since it is in a cured state, the surface is sticky, so that resin residue generated in the development process is likely to adhere, which often causes problems in the printing process.

  Therefore, especially in the plate making of a thick relief layer where the back exposure cannot be performed, in order to stably reproduce the minute protrusions, the relief shape can be stably reproduced during curing by main exposure. It is an important issue to make it happen.

  As for the type of light source of the exposure machine that performs the main exposure, a single light source typified by a lamp that generates ultraviolet light is known, a type in which a plurality of light sources are arranged in a plane at regular intervals, and the latter is known. In addition to the ultraviolet light from the top of the vertical, the exposed area also includes ultraviolet light from obliquely above, so the area of the bottom of the relief after development has the advantage of being largely stable, while the concave portions such as white areas are shallow. There is a demerit that it easily leads to a trouble that ink adheres to the non-image area during printing.

  As a document relating to the relief shape, Patent Document 1 proposes a method for producing a flexographic printing plate in which the angle between the relief parietal surface and the side surface is 90 ° or more and 100 ° or less, and a method for producing a printed matter using the same. Yes. However, since the relief width is relatively large at 100 μm and the first photosensitive resin layer is used as a floor layer, the relief depth is as shallow as 200 μm, and a method for forming a minute projection having a deep relief depth is as follows. It is insufficient.

  Further, in Patent Document 2, it is possible to produce a semi-transparent film having an optimum ultraviolet light transmittance for each predetermined pattern, and obtain an appropriate relief shoulder angle by attaching and exposing the film. A method has been proposed. However, in this method, it is necessary to attach a plurality of semi-transmissive films having different ultraviolet light transmittances for each pattern, and the work becomes complicated. Further, the illustrated lines having a width of 0.1 mm or more are relatively large. Because of the size, the effectiveness of small convex portions such as narrow lines such as 50 μm or less is unknown.

  Further, Non-Patent Document 1 discloses a method of exposing through a diffusion plate called a diffuser for adjusting the relief shape by scattering incident light to an exposure machine for making a printing plate. Therefore, there is a problem that a concave portion such as a white image becomes shallow, and a problem that ink adheres to a non-image portion in actual printing is likely to occur.

  Therefore, for example, in a plate making of a photosensitive printing original plate that has a thick relief layer and cannot be subjected to a method such as back exposure like a flexographic printing plate, it is extremely difficult to obtain a plate having a deep relief depth and reproducing minute convex portions. It was difficult.

Patent No. 4080839 Japanese Patent Publication 3-65538

Operation manual of OLEC exposure machine “OV45HD”

  An object of the present invention is to provide a printing plate in which minute convex portions having a deep relief depth are stably reproduced in view of the above-described problems of the prior art.

In order to solve the above problems, the present invention mainly requires the following configuration. That is,
In a photosensitive printing plate precursor having at least a support, a photosensitive resin layer (A), and a thermal mask layer (C) in this order, the thermal mask layer (C) is patterned using an infrared laser, and then photosensitive. A method for producing a printing plate for letterpress printing, characterized in that a diffusion film (F) having a light diffusion angle of 40 ° or more is disposed on a printing plate precursor, and exposure and development are performed.

  The printing plate produced by the production method of the present invention makes it possible to obtain high image reproducibility with a stable shape even by plate making using a plate having an opaque substrate or an exposure machine having a point light source.

  The photosensitive printing plate precursor used in the production method of the present invention has at least a photosensitive resin layer (A) for forming a relief layer and a thermal mask layer (C) in this order on a support.

  The photosensitive resin layer (A) in the photosensitive printing plate precursor used in the present invention comprises a base polymer (a1), an ethylenically unsaturated compound (a2) that can be crosslinked by radical polymerization, and a photopolymerization initiator (a3). Including.

  Although there is no restriction | limiting in particular as base polymer (a1) used for this invention, In the image development process after main exposure, it is necessary for an unexposed part to be removed appropriately with a developing solution.

  The ethylenically unsaturated compound (a2) used in the present invention is a compound that can be cross-linked by radical polymerization and has a function of imparting strength to the cured photosensitive resin layer. For example, 2-hydroxyethyl (meta ) Acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, 3-hydroxy-β ′-(meth) acryloyloxyethyl phthalate, etc. (Meth) acrylate having hydroxyl group, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) Acrylate, stearyl Alkyl (meth) acrylates such as meth) acrylate, cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate, halogenated alkyl (meth) acrylates such as chloroethyl (meth) acrylate and chloropropyl (meth) acrylate, methoxyethyl ( Alkoxyalkyl (meth) acrylates such as meth) acrylate, ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, phenoxyalkyl (meth) acrylates such as phenoxyethyl acrylate, nonylphenoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) ) Acrylate, methoxytriethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate Alkoxyalkylene glycol (meth) acrylate such as (meth) acrylamide, diacetone (meth) acrylamide, (meth) acrylamides such as N, N′-methylenebis (meth) acrylamide, 2,2-dimethylaminoethyl (meth) acrylate , 2,2-diethylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, etc., having only one ethylenically unsaturated bond Compound, Polyethylene glycol di (meth) acrylate such as diethylene glycol di (meth) acrylate, Polypropylene glycol di (meth) acrylate such as dipropylene glycol di (meth) acrylate, Trimethylol Pro Ethylenically unsaturated bonds such as unsaturated carboxylic acids and unsaturated alcohols to N (tri) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol tri (meth) acrylate, ethylene glycol diglycidyl ether 2 or more in a molecule such as polyvalent (meth) acrylate obtained by addition reaction of a compound having hydrogen with active hydrogen, polyvalent (meth) acrylamide such as methylenebis (meth) acrylamide, and polyvalent vinyl compound such as divinylbenzene And compounds having an ethylenically unsaturated bond. Two or more of these may be contained.

  The photopolymerization initiator (a3) used in the present invention is not particularly limited as long as it has a function of generating radicals by self-cleavage or hydrogen abstraction. For example, known photopolymerization initiators such as acetophenones, benzoin ethers, benzophenones, thioxanthones, anthraquinones, benzyls, biacetyls and the like can be mentioned. Two or more of these may be contained. Among the above photopolymerization initiators, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone and the like are preferably used in the present invention.

  The photosensitive resin layer (A) of the photosensitive printing plate precursor used in the present invention has a defoaming agent, an ultraviolet absorber, an oxygen scavenger, a sensitizer, a colorant (dye) for the purpose of further improving various properties. , Pigments, photochromic agents, coloring aids), perfumes, deodorants, solvents and the like.

  The heat-sensitive mask layer (C) in the photosensitive printing plate precursor used in the present invention is disposed on the photosensitive resin layer (A) and is insoluble or swellable in the developer of the photosensitive resin layer (A). It contains two or more types of binder polymer (c1), one or more types of infrared absorbing material (c2) and a non-infrared shielding material (c3). Non-infrared light means light other than infrared light, such as ultraviolet light. The infrared absorbing material (c2) and the non-infrared light shielding material (c3) may be the same or different, and carbon black is preferably used as one of the materials that serve as both. Moreover, you may provide the adhesive force adjustment layer (B) which promotes adhesion | attachment of a heat sensitive mask layer (C) and the photosensitive resin layer (A) in the range which does not impair the effect of this invention. The method for forming the heat-sensitive mask layer (C) is not particularly limited. For example, by dissolving and diluting a resin in which carbon black is dispersed with an appropriate solvent, applying the solution on the photosensitive resin layer, and drying the solvent, A thermal mask layer (C) can be formed. Alternatively, the above-described carbon black solution may be applied once to a film of polyester or the like and then laminated so that the photosensitive resin layer is sandwiched between this film (referred to as cover film (E)) and a support. Moreover, you may provide the peeling auxiliary | assistant layer (D) which adjusts the peeling force of a thermal mask layer (C) and a cover film (E) in the range which does not impair the effect of this invention.

  The diffusion film (F) used for the production of the relief printing plate of the present invention needs to have suitable ultraviolet light transmittance and light diffusing ability, and is a transparent support such as a polyester film. There is no particular limitation as long as particles or layers for suitably diffusing incident light are formed on or inside. If the ultraviolet light transmittance of the diffusion film (F) is 50% or more, the problem that the exposure time becomes long or necessary to obtain the integrated light amount of ultraviolet light necessary for the main exposure through the diffusion film (F), or necessary It is easy to avoid the problem that the depth of the white image becomes shallow because the accumulated light amount of the ultraviolet light irradiated to the relief concave portion becomes too high while obtaining the cumulative light amount of the ultraviolet light, or the relief convex portion of the printing plate This is preferable because the bottom shape becomes unstable and it is easy to avoid problems such as falling or disappearing. The light diffusing ability of the diffusion film (F) used in the present invention can be expressed by the value of the light diffusion angle, and the light diffusion angle needs to be 40 ° or more. When the light diffusion angle is 40 ° or more, the incident light is preferably diffused and the relief shape is easily stabilized. The diffusion angle of the light diffusion film (F) is defined as twice the angle at which the relative intensity with respect to the highest transmitted light intensity perpendicularly incident on the film is halved. In general, the light scattering ability of the diffusion film (F) is improved by the particles and layers on the substrate. Although the light transmittance is reduced by the amount of reflected light, the type of diffusion film (F) having a structure in which microlens arrays are randomly arranged on a substrate diffuses incident light at an arbitrary angle. It is preferable because it is easy to suppress a decrease in light transmittance while obtaining light with high homogeneity.

  The method for producing a relief printing plate according to the present invention uses the above-mentioned photosensitive printing plate precursor, and (1) image-wise irradiation of the thermal mask layer (C) with an infrared laser to form an image mask (C ′). Step of forming, (2) A diffusion film (F) having a light scattering angle of 40 ° or more is arranged on the photosensitive printing plate precursor from the formed image mask (C ′) side, and exposed to ultraviolet light to be photosensitive. A step of forming a latent image on the resin layer (A), (3) development processing with a liquid containing water as a main component, and removing the image mask (C ′) and the photosensitive resin layer (A) in the ultraviolet light unexposed area. Process.

  When the cover film (E) and the peeling auxiliary layer (D) or the cover film (E) are present, at least the cover film (E) is peeled, and then an infrared laser is imaged on the thermal mask layer (C). Imagewise irradiation is preferably performed to form an image mask (C ′). More preferably, after the peeling auxiliary layer (D) and the cover film (E) are present and only the cover film (E) is peeled off, the thermal mask layer (C) is imagewise irradiated with an infrared laser. Forming an image mask (C ′).

  (1) The step of forming an image mask (C ′) by irradiating the thermal mask layer (C) imagewise with an infrared laser is to turn on / off the infrared laser based on image data, This is a step of scanning irradiation with respect to (C). When the thermal mask layer (C) is irradiated with an infrared laser, heat is generated by the action of the infrared absorbing material, and the thermal decomposable compound is decomposed by the action of the heat to remove the thermal mask layer (C). Laser ablation. The laser ablated portion has a greatly reduced optical density and is substantially transparent to ultraviolet light. An image mask (C ′) capable of forming a latent image on the photosensitive resin layer (A) is obtained by selectively laser ablating the thermal mask layer (C) based on the image data.

  For infrared laser irradiation, those having an oscillation wavelength in the range of 750 to 3000 nm are used. Examples of such lasers include ruby lasers, alexandrite lasers, perovskite lasers, solid state lasers such as Nd-YAG lasers and emerald glass lasers, semiconductor lasers such as InGaAsP, InGaAs and GaAsAl, and dye lasers such as rhodamine dyes. Can be mentioned. A fiber laser that amplifies these light sources with a fiber can also be used. Among them, the semiconductor laser is preferable because it is downsized due to recent technological advances and is economically advantageous over other laser light sources. An Nd-YAG laser is also preferable because it has a high output, is widely used for dentistry and medical purposes, and is economically inexpensive.

  (2) A diffusion film (F) having a light scattering angle of 40 ° or more is disposed on the photosensitive printing plate precursor from the formed image mask (C ′) side, and ultraviolet light is exposed to the photosensitive resin layer (A The latent image is formed on the photosensitive printing plate precursor that has been laser-irradiated by the above method, and the diffusion film (F) is disposed on the photosensitive printing plate precursor, and ultraviolet light, preferably ultraviolet light having a wavelength of 300 to 400 nm, is applied. In this step, the entire surface is exposed through an image mask (C ′) on which an image is formed by a laser, and the photosensitive resin layer (A) below the laser ablation portion in the image mask (C ′) is selectively photocured. is there.

In the exposure, it is preferable to dispose the diffusion film (F) only in the portion where the convex portion is formed on the printing plate in the patterned image mask (C ′). By arranging in this way,
A printing plate with good reproducibility of fine lines and a large white depth can be produced.

  Moreover, since ultraviolet light also enters from the side surface of the photosensitive resin printing plate precursor during exposure, it is preferable to cover the side surface with a cover that does not transmit ultraviolet light. As a light source capable of exposing a wavelength of 300 to 400 nm, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a xenon lamp, a carbon arc lamp, a chemical lamp, or the like can be used. In the photosensitive resin layer (A), the portion exposed to ultraviolet light changes to a substance that cannot be eluted and dispersed by the developer.

  (3) The step of developing with a liquid containing water as a main component to remove the image mask (C ′) and the photosensitive resin layer (A) in the ultraviolet light unexposed area is, for example, the photosensitive resin layer (A). It is achieved by developing using a brush type washing machine having a developer mainly composed of water that can dissolve and disperse. Through this step, a portion exposed by ultraviolet light remains, and a relief printing plate having a relief image is obtained.

  In these developing solutions, those in which components such as the photosensitive resin layer (A) and the thermal mask layer (C) are mixed can be used.

  The image mask (C ′) can be physically removed by rubbing with a strong brush such as PBT (polybutylene terephthalate).

  Thereafter, if necessary, a step of drying the developer adhering to the plate surface, a post-exposure step of the photosensitive resin printing plate material, an adhesive removal treatment step, and the like can be performed.

  The relief printing plate produced by the production method of the present invention is preferably used as a relief printing plate that can be mounted on a printing press.

  Hereinafter, the present invention will be described in detail with reference to examples.

<Synthesis Example 1 (Synthesis of Modified Polyvinyl Alcohol 1)>
In a flask equipped with a condenser, partially saponified polyvinyl alcohol “J Poval” (registered trademark) JR-05 (degree of saponification 72%, manufactured by Nihon Vinegar Bipoval Co., Ltd.) 50 parts by weight, succinic anhydride 2 parts by weight and acetone 10 parts by weight was added and heated at 60 ° C. for 6 hours, and then the condenser was removed to volatilize acetone. Thereafter, the purification step of eluting unreacted succinic anhydride with 100 parts by weight of acetone was carried out twice, followed by drying under reduced pressure at 60 ° C. for 5 hours to obtain modified polyvinyl alcohol 1 in which succinic acid was ester-bonded to a hydroxyl group. Obtained.

<Preparation of coating liquid composition 1 for photosensitive resin layer (A1)>
In a mixed solvent having a water / ethanol ratio of 55/45 (weight ratio), 100 parts by weight of the modified polyvinyl alcohol obtained in Synthesis Example 1, 23 parts by weight of glycerin manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., 8 weights of diethylene glycol manufactured by Mitsubishi Chemical Corporation Part was added and dissolved by stirring at 70 ° C. for 2 hours. Next, 3 parts by weight of “Blenmer” (registered trademark) G manufactured by NOF Corporation was added as an ethylenically unsaturated compound and stirred at 70 ° C. for 0.5 hour. Furthermore, NOF "Blemmer" GMR 8 parts by weight, Kyoeisha Chemical "epoxy ester" 70PA 10 parts by weight, NOF "Blenmer" PE-350 35 parts by weight 1 part by weight of “Irgacure” (registered trademark) 65 manufactured by Ciba Japan Co., Ltd. and 3 parts by weight of “Irgacure” 184 as a photopolymerization initiator and Wako Pure Chemical Industries, Ltd. as a polymerization inhibitor 0.02 part by weight of “Q-1300”, 0.02 part by weight of “Chinubin” (registered trademark) 326 manufactured by Ciba Japan Co., Ltd. as a UV absorber, and “Violet FBW” dye manufactured by Nippon Kayaku Co., Ltd. "0.04 parts by weight" was added and stirred at 70 ° C for 0.5 hours to obtain a coating composition 1. At this time, the solid content concentration of the coating composition 1 was adjusted to 60% by weight. When the solution was visually confirmed, no separation or turbidity of the solution was observed, and the solution was uniform.

<Preparation of adhesive coated substrate 1>
A mixture of 260 parts by weight of a toluene solution “Byron” (registered trademark) 31SS of polyester resin manufactured by Toyobo Co., Ltd. and 2 parts by weight of benzoin ethyl ether “PS-8A” manufactured by Wako Pure Chemical Industries, Ltd. at 70 ° C. for 2 hours. After heating, the mixture was cooled to 30 ° C., 7 parts by weight of ethylene glycol diglycidyl ether dimethacrylate was added and mixed for 2 hours. Furthermore, 25 parts by weight of ethyl acetate solution “Coronate” (registered trademark) 3015E of polyisocyanate resin manufactured by Nippon Polyurethane Industry Co., Ltd. and 14 parts by weight of industrial adhesive “EC-1368” manufactured by Sumitomo 3M Co., Ltd. This was added to obtain an adhesive composition 1.

  50 parts by weight of polyvinyl alcohol “GOHSENOL” (registered trademark) KH-17 (saponification degree: 78.5% to 81.5%) manufactured by Nippon Synthetic Chemical Industry Co., Ltd., alcohol mixture “Solmix” manufactured by Nippon Alcohol Co., Ltd. "(Registered trademark) H-11 200 parts by weight and 200 parts by weight of water were used for dissolution at 70 ° C. for 2 hours, and then 1.5 parts by weight of“ Blemmer ”G made by NOF Corporation was added. After mixing for 3 hours, 3 parts by weight of (dimethylaminoethyl methacrylate) / (2-hydroxyethyl methacrylate) copolymer of 2/1 by Kyoeisha Chemical Co., Ltd., “Irgacure” manufactured by Ciba Geigy Co., Ltd. (Registered Trademark) 651 5 parts by weight, Kyoeisha Chemical Co., Ltd. "Epoxyester" 70 PA and 21 parts by weight ethylene glycol diglycidyl ether dimethacrylate Add 20 parts by weight of the mixture, mix for 90 minutes, cool to 50 ° C., add 0.1 part by weight of “Florad” (registered trademark) TM FC-430 manufactured by Sumitomo 3M, and mix for 30 minutes. An adhesive composition 2 was obtained.

  On the polyester film “Lumirror” (registered trademark) T60 (thickness 180 μm) manufactured by Toray Industries, Inc., the adhesive composition 1 was applied with a bar coater so that the film thickness after drying was 40 μm. After removing the solvent for a minute, the adhesive composition 2 was coated thereon with a bar coater so that the dry film thickness was 30 μm, and dried in an oven at 160 ° C. for 3 minutes to obtain an adhesive coated substrate 1.

<Manufacture of photosensitive resin sheet 1>
After the adhesive-coated substrate 1 is exposed to 1000 mJ / cm 2 with an ultrahigh-pressure mercury lamp from the adhesive-coated side, the coating liquid composition 1 for the photosensitive resin layer (A1) is applied to the adhesive-coated surface of the adhesive-coated substrate 1. It was cast and dried in an oven at 60 ° C. for 5 hours to obtain a photosensitive resin sheet 1 having a thickness of 1900 μm including the substrate. The thickness of the photosensitive resin sheet 1 was controlled by setting a spacer having a predetermined thickness on the substrate and scraping out the coating liquid composition 1 in a portion protruding from the spacer with a horizontal metal scale.

<Preparation of Coating Solution Composition 2 for Adhesive Strength Adjustment Layer (B1)>
11 parts by weight of polyvinyl alcohol “Gosenol” (registered trademark) KL-05 (saponification degree: 78.5% to 82%) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. 55 parts by weight of water, 14 parts by weight of methanol, n-propanol 10 By dissolving in 10 parts by weight of n parts and n-butanol, a coating liquid composition 2 for the adhesion adjusting layer (B1) was obtained.

<Preparation of coating liquid composition 3 for thermal mask layer (C1)>
23 parts by weight of carbon black “MA100” manufactured by Mitsubishi Chemical Corporation, 15 parts by weight of alcohol-insoluble acrylic resin “Dianar” (registered trademark) BR-95 manufactured by Mitsubishi Rayon Co., Ltd. A carbon black dispersion 1 was prepared by kneading and dispersing 6 parts by weight of tributyl acid and 30 parts by weight of methyl isobutyl ketone using a three-roll mill. In dispersion 1, 20 parts by weight of epoxy resin “Araldite” (registered trademark) 6071 manufactured by Asahi Ciba Co., Ltd., 27 parts by weight of melamine resin “Uban” (registered trademark) 2061 manufactured by Mitsui Chemicals, Inc., Kyoeisha Chemical Co., Ltd. ) 0.7 parts by weight of phosphoric acid monomer “light ester” (registered trademark) P-1M and 140 parts by weight of methyl isobutyl ketone were added and stirred for 30 minutes. Thereafter, methyl isobutyl ketone was further added so that the solid content concentration was 33% by weight to obtain a coating liquid composition 3 for the thermal mask layer (C1).

<Preparation of coating liquid composition 4 for peeling auxiliary layer (D1)>
11 parts by weight of polyvinyl alcohol “GOHSENOL” AL-06 (saponification degree 91% to 94%) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. 55 parts by weight of water, 14 parts by weight of methanol, 10 parts by weight of n-propanol and n-butanol It melt | dissolved in 10 weight part and obtained the coating liquid composition 4 for peeling auxiliary | assistant layer (D1).

<Manufacture of thermal mask element 1>
The coating liquid composition 4 was applied on a 100 μm thick chemically matted polyester film (Ra 0.4 μm) (E1) using a bar coater so that the dry film thickness was 0.3 μm. It dried for 2 second, and the laminated body of peeling auxiliary | assistant layer (D1) / cover film (E1) was obtained. On the peeling auxiliary layer (D1) side of the laminate thus obtained, the coating liquid composition 3 was applied to a dry film thickness of 2 μm using a bar coater, dried at 140 ° C. for 30 seconds, A laminate of thermal mask layer (C1) / peeling auxiliary layer (D1) / cover film (E1) was obtained. On the thermal mask layer (C1) side of the laminate thus obtained, the coating liquid composition 2 was applied using a bar coater so that the dry film thickness was 0.5 μm, and dried at 140 ° C., A thermal mask element 1 which is a laminate of adhesion adjusting layer (B1) / thermal mask layer (C1) / peeling auxiliary layer (D1) / cover film (E1) was obtained.

<Manufacture of photosensitive resin printing original plate>
A calender roll heated to 80 ° C. with the heat-sensitive mask element 1 placed on the photosensitive resin layer (A1) of the photosensitive resin sheet 1 so that the adhesive force adjusting layer (B1) is in contact with the photosensitive resin layer (A1). Are laminated in the order of adhesive coated substrate 1 / photosensitive resin layer (A1) / adhesive strength adjusting layer (B1) / thermal mask layer (C1) / peeling auxiliary layer (D1) / cover film (E1). A photosensitive printing plate precursor 1 was obtained. The clearance of the calendar roll was adjusted so that the thickness of the laminate after peeling the cover film layer (E1) from the photosensitive printing plate precursor 1 was 1800 μm. The developed coating liquid composition 1 is allowed to stand for 1 week after laminating, whereby the remaining solvent is naturally dried to form the photosensitive resin layer (A1).

<Manufacture of printing original plate through plate making process>
After peeling the cover film (E1) from the photosensitive printing plate precursor 1, the thermal mask layer (C1) was examined on a light table. The thermal mask layer was broken and the number of pinholes of thermal mask layer of 50 μm or more / 10 cm ^2. Was 0. After that, the outer drum type plate setter “CDI SPARK” (manufactured by ESCO Graphics Co., Ltd.) equipped with a fiber laser having a light emitting region in the infrared is mounted so that the substrate side is in contact with the drum, and a test pattern (thin line: long) The length is 3 cm, and the width is 50 μm, 40 μm, 30 μm, 20 μm, and 10 μm, respectively. And 100 μm width two) were laser-drawn under the conditions of a laser output of 9 W and a drum rotation speed of 500 rpm to form an image mask (C1 ′) from the thermal mask layer (C1). At this time, the burnt residue / cm ² of the solid portion of φ20 μm or more was zero.

<Manufacture of printing plate after exposure and development process>
Subsequently, the entire surface was exposed with an ultrahigh pressure mercury lamp (manufactured by Oak Co., Ltd.) having a diffusion film (F) on the image mask (C1 ′) side and having a light source in the ultraviolet region. The main exposure was carried out while changing the exposure amount (the exposure amount level of the main exposure is described in <Reference Example> described later). Next, using a batch type developing machine equipped with a PBT (polybutylene terephthalate) brush, development was performed with tap water at 25 ° C. for 3 minutes. As a result, the peeling auxiliary layer (D1), the image mask (C1 ′) and A portion of the photosensitive resin layer (A1) that was blocked by the image mask and not exposed to ultraviolet rays was selectively developed to reproduce a negative relief with respect to the image mask (C1 ′). The relief depth was the same as that of the photosensitive resin layer (A1), and there was no insufficient development. Then, it dried for 10 minutes at 60 degreeC. Thereafter, post-exposure was performed for 2500 mj / cm for ² minutes on the entire surface of the printing plate using the ultrahigh pressure mercury lamp described above to obtain a printing plate for evaluation. Further, the photosensitive resin layer (A1) is stacked to a thickness of 5 mm, and the durometer hardness is measured by a method defined in JIS K6253-3 (2012) using a type A durometer under conditions of room temperature 20 ° C. and humidity 50%. As a result of measurement, there was no difference at 71 ° at any main exposure level.

<Method for evaluating image reproducibility of printing plate>
(1) Fine line: The minimum line width that was reproduced vertically without falling a thin line of 4 cm length or having its end separated from the substrate in a bowl shape, bent or fallen was counted. When the line width exceeds 50 μm, ×, if a thin line having a width of 50 μm or less is reproduced, ◯, and when a thin line having a width of 30 μm or less is reproduced, ◎.
(2) Open line: The depth of the deepest portion of a cross section of 4 cm long and 100 μm wide observed with an optical microscope was measured. When the depth of 40 μm or more was secured, it was judged as “◯”, when the depth of 30 μm or more was secured, “△”, and when the depth was less than 30 μm, it was judged as “x”.

<Evaluation method of ultraviolet light transmittance of diffusion film (F)>
When using the integrated light meter “UV-Integrator 14” manufactured by Kuhnast Radiation Technology for 1 minute exposure using the ultra-high pressure mercury lamp, {integrated light amount when exposed through diffusion film (F)} / {diffusion film ( F) Accumulated light quantity in the case of none} × 100 (%).

Reference example 1
The above-described photosensitive printing plate precursor was subjected to main exposure without a diffusion film. The main exposure levels were 2500, 5000, 10000, 15000, and 20000 mj / cm ² , respectively. When the image reproducibility of the printing plate at this time was evaluated, thin lines having a width of 50 μm or less were not reproduced on the printing plate at an exposure amount up to 10000 mj / cm ² . A thin line having a width of 50 μm was reproduced at an exposure amount of 15000 mj / cm ² , and the depth of the white area of 100 μm was 62 μm. In addition, a thin line having a width of 30 μm was reproduced at an exposure amount of 20000 mj / cm ² , but the white depth of 100 μm was 36 μm, and it was determined that the exposure amount was excessive. Therefore, in the following examples, the exposure amount was fixed at 15000 mj / cm ² , each diffusion film was placed, image reproducibility was confirmed, and a comparative evaluation was made with a printing plate made without a diffusion film.

Example 1
Luminit's lens diffusion plate “LSD40PC10-F5” (a type in which a diffusion layer is formed on a polycarbonate substrate with a thickness of 250 μm. Ultraviolet light transmittance 65%, light diffusion angle 40 °) is used as a diffusion film. Is placed on the fine line image patterned with an infrared laser so that the diffusion layer faces away from the thermal mask layer, the main exposure is performed at an exposure amount of 15000 mj / cm ² , and development and drying are performed. Got a version. The fine line of the obtained printing plate was reproduced to a width of 30 μm (the thin line with a width of 20 μm was in a state of falling in a bowl shape at the end).

Example 2
Luminit's lens diffusion plate “LSD60PC10-F5” (a type in which a micro-sized lens array is randomly formed on a polycarbonate substrate having a thickness of 250 μm. Ultraviolet light transmittance 58%, light diffusion angle 60 °) When the plate was made in the same manner as in Example 1 except that was used, the fine line of the printing plate was reproduced up to a width of 20 μm (the thin line of the width of 10 μm was in a state of being saddle-shaped and falling down).

Example 3
Luminit's lens diffusion plate “LSD80PC10-F5” (a type in which a micro-sized lens array is randomly formed on a polycarbonate substrate having a thickness of 250 μm. Ultraviolet light transmittance 51%, light diffusion angle 80 °) When the plate was made in the same manner as in Example 1 except that was used, the fine line of the printing plate was reproduced to a width of 10 μm.

Example 4
Light diffusion film “D123” (manufactured by Tsujiden Co., Ltd.) (Diffusion layer is laminated on a polyester substrate with a thickness of 100 μm. Ultraviolet light transmittance 35%, haze value 82%, light diffusion angle 76 °) And the plate was reproduced in the same manner as in Example 1 except that the diffusion layer was arranged so as to be adjacent to the plate surface. The fine line of the printing plate was reproduced up to 40 μm wide (the 30 μm wide thin line had an end portion). It was in a state of falling like a saddle).

Example 5
Light diffusion film “D123” (manufactured by Tsujiden Co., Ltd.) (Diffusion layer is laminated on a polyester substrate with a thickness of 100 μm. Ultraviolet light transmittance 35%, haze value 82%, light diffusion angle 76 °) The diffusion mask was placed not only on the fine line image of the plate surface from which the thermal mask layer was removed by laser but also on the white image so that the diffusion layer was adjacent to the plate surface, thereby creating a state where the diffusion plate covered the entire plate. In this state, main exposure was performed at an exposure amount of 15000 mj / cm ² , development and drying were performed to obtain a printing plate. The fine line of the obtained printing plate was reproduced to a width of 40 μm as in Example 4, but the white depth was as shallow as 35 μm, but it was judged that it could be used for printing.

Comparative Example 1
As a diffusion film, a diffusion adhesive film for display “TD06D0175” manufactured by Yodogawa Paper Co., Ltd. (a type in which an adhesive layer having a diffusion function is formed on a polyester substrate having a thickness of 100 μm. Ultraviolet light transmittance 82%, haze value) When the plate was made in the same manner as in Example 2 except that the adhesive layer was placed in contact with the heat-sensitive mask layer (75%, light diffusion angle 4 °), the fine line of the printing plate was reproduced to a width of 50 μm (40 μm width). The end of the thin wire was in the state of being saddle-shaped and falling down).

Comparative Example 2
As a diffusion film, a diffusion adhesive film for display “TD06D0150” manufactured by Yodogawa Paper Co., Ltd. (adhesive layer having a diffusion function formed on a polyester substrate having a thickness of 100 μm. Ultraviolet light transmittance 84%, haze value) When the plate was made in the same manner as in Example 2 except that 50% and a light diffusion angle of 5 ° were used, the fine line of the printing plate was reproduced to a width of 50 μm (the thin line of 40 μm width had a bowl-like end. It was in a fallen state).

Comparative Example 3
Light diffusion film “D121UP” (manufactured by Tsujiden Co., Ltd.) (Diffusion layer laminated on 100 μm thick polyester base. Ultraviolet light transmittance 57%, haze value 79%, light diffusion angle 23 °) When the plate was made in the same manner as in Example 1 except that was used, the fine line of the printing plate was reproduced up to a width of 50 μm (the thin line of the width of 40 μm had a saddle-like end and fell down).

Comparative Example 4
As diffusion film, diffusion sheet “D114” manufactured by Tsujiden Co., Ltd. (type in which a diffusion layer is laminated on a polyester substrate with a thickness of 100 μm. Ultraviolet light transmittance 44%, haze value 81%, light diffusion angle 38 °) When the plate was made in the same manner as in Example 1 except that it was used, the fine line of the printing plate was reproduced up to a width of 50 μm (the thin line of the 40 μm width was in a state of falling in a bowl shape at the end).

Comparative Example 5
Luminit's lens diffusion plate “LSD20PC10-F5” (a type in which a polycarbonate substrate micro-sized lens array with a thickness of 250 μm is randomly formed. Ultraviolet light transmittance 79%, light diffusion angle 20 °) is used as a diffusion film. When the plate was made in the same manner as in Example 1, the fine line of the printing plate was reproduced to a width of 50 μm (the thin line of the 40 μm width was in a state where the end portion was saddle-shaped and collapsed).

  The relief printing plate produced by the production method of the present invention includes a relief for printing such as letterpress printing and flexographic printing, as well as stamp, seal, foil stamping, embossing, prototype of molded product, master mold It can be applied and used for other purposes.

Claims (4)

In a photosensitive printing plate precursor having at least a support, a photosensitive resin layer (A), and a thermal mask layer (C) in this order, the thermal mask layer (C) is patterned using an infrared laser, and then photosensitive. A method for producing a relief printing plate, comprising: diffusing a film (F) having a light diffusion angle of 40 ° or more on a printing plate precursor; The method for producing a relief printing plate according to claim 1, wherein the diffusion film (F) has an ultraviolet light transmittance of 50% or more. 3. The relief printing plate according to claim 1, wherein the diffusion film has a structure in which micron-sized lens structures are randomly arranged and diffuse at an arbitrary angle. Manufacturing method. In the manufacturing method of a relief printing plate, a diffusion film (F) is arrange | positioned only in the area | region which forms a convex part in a printing plate in the thermal mask layer (C) processed into a pattern. The manufacturing method of the printing plate for letterpress printing of 1-3.