JP2016163950A - Resin printing plate precursor for laser engraving - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin printing plate precursor for laser engraving which is capable of forming a relief having an excellent engraving adaptability by laser engraving and which is capable of providing a printing plate excellent in flexibility, ink deposition properties during printing, and reusability.SOLUTION: The resin printing plate precursor for laser engraving includes a support and a resin layer on the support. The resin layer comprises (A) a water-soluble polymer or water-swellable polymer, (B) an ethylenically unsaturated compound, and (C) a photopolymerization initiator, in which the ethylenically unsaturated compound (B) comprises a compound (b) having a polyethylene glycol skeleton and only one ethylenically unsaturated bond in the molecule and having a weight average molecular weight of 400 to 800. The resin printing plate precursor contains 20 to 65 parts by mass of the component (B) with respect to 100 parts by mass of the component (A), and the content of the compound (b) is 20 to 50 mass% with respect to the component (B).SELECTED DRAWING: None

Description

  TECHNICAL FIELD The present invention relates to a resin printing plate precursor for laser engraving and a method for producing a printing plate using a resin printing plate precursor for laser engraving, and in particular, a printing plate precursor suitable for flexographic printing and form printing, and the printing plate precursor. The present invention relates to a printing plate manufacturing method.

As a method for forming a relief plate by forming irregularities on the surface, a photosensitive elastomer composition or a photosensitive resin composition is used, these compositions are exposed to ultraviolet light through an original film, and an image portion is selectively selected. The so-called “analog plate-making” method is well known in which an uncured portion is removed using a developer.
In many cases, analog plate making requires an original film using a silver salt material, and thus requires production time and cost of the original film. Furthermore, since chemical processing is required for developing the original image film and processing of the development waste liquid is also required, there is a disadvantage in environmental hygiene.

  As a technique for solving the problems associated with analog plate making, a resin relief printing plate precursor having a laser-sensitive mask layer element capable of forming an image mask in situ on a photosensitive resin layer has been proposed. (For example, refer to Patent Documents 1 and 2). In the plate making method of these original plates, laser irradiation is performed based on image data controlled by a digital device, an image mask is formed on the spot from a mask layer element, and thereafter, through an image mask as in analog plate making. It is a plate making method that exposes with ultraviolet light or develops and removes the photosensitive resin layer and the image mask, and is called “CTP method” in the resin letterpress industry. Although the CTP method solves the problems related to the production process of the original film described above, there is a problem related to the treatment of the waste liquid generated in the development of the photosensitive resin layer.

  As another means for solving the problems relating to the development process and the development waste liquid, many direct engraving plate making using laser, so-called “laser engraving” has been proposed. Laser engraving literally engraves with a laser to form reliefs, and has the advantage that the relief shape can be freely controlled, unlike relief formation using an original film. For example, in a portion that reproduces a fine halftone dot, such as deeply engraving a blank character portion, a shoulder can be engraved so that the halftone dot does not fall down due to the printing pressure. The laser engraving suitability varies depending on the plate material, and the deeper the engraving depth is when the laser is irradiated with a certain energy, the higher the laser engraving sensitivity, and the shorter the time required for the laser engraving process. Further, a so-called rinsing process for removing residue generated by laser engraving is necessary. However, if it can be removed with water without using a solvent, the environmental burden can be reduced while ensuring safety.

  Patent Documents 3 to 5 disclose resin letterpress original plates capable of laser engraving or resin letterpress obtained by laser engraving. These are highly suitable for laser engraving, such as laser engraving sensitivity and rinsing properties, but have a plate material hardness suitable for letter press printing, not suitable for flexographic printing, and are suitable for laser engraving and flexibility suitable for flexographic printing. It is difficult to obtain a printing plate that satisfies both of the above and a high level.

Japanese Patent No. 2773847 (pages 3-9) JP-A-9-171247 (pages 3-7) JP-A-11-170718 (page 4) JP 2000-168253 A (page 2-6) JP 2001-328365 A (page 2-9)

  The present invention has been made in view of the above circumstances, can form a relief by laser engraving, has excellent engraving suitability of the relief, and also has flexibility, ink inking during printing, and reusability. An object of the present invention is to provide a resin printing plate precursor for laser engraving capable of obtaining an excellent printing plate.

  In order to achieve the above object, the resin printing plate precursor of the present invention has the following constitution. That is, it has a support and a resin layer on the support, and the resin layer contains a water-soluble polymer or a water-swellable polymer (A), an ethylenically unsaturated compound (B), and a photopolymerization initiator (C). The ethylenically unsaturated compound (B) contains a compound (b) having a weight average molecular weight of 400 to 800 having a polyethylene glycol skeleton and having only one ethylenically unsaturated bond in the molecule, and the component (A ) 20 to 65 parts by mass of the component (B) with respect to 100 parts by mass, and the content of the compound (b) is 20 to 50% by mass with respect to the component (B). A resin printing plate precursor that is a photosensitive resin composition is provided.

  According to the present invention, it is possible to obtain a relief printing plate that is compatible with laser engraving suitability and flexibility and is excellent in ink deposition and reusability during printing.

  Embodiments of the present invention will be described below.

  The water-soluble polymer or water-swellable polymer (A) in the present invention means a polymer that dissolves or disperses when immersed in water at 25 ° C. for 24 hours. It has a function as a carrier for maintaining the form of the photosensitive resin composition in a solid state and a function of imparting water developability to the photosensitive resin layer. Examples of the water-soluble polymer or water-swellable polymer (A) include polyvinyl alcohol, polyvinyl acetate, partially saponified polyvinyl acetate (partially saponified polyvinyl alcohol), cellulose resin, ethylene / vinyl acetate copolymer, and hydrophilicity. Examples thereof include polyamide resins into which groups have been introduced, and modified products of these resins. Two or more of these may be contained. Of these, polyvinyl alcohol, partially saponified polyvinyl alcohol, polyamide resin having a hydrophilic group introduced therein, and modified products of these resins are preferably used.

  The ethylenically unsaturated compound (B) is a compound that can be cross-linked by radical polymerization, and has a function of imparting strength to the cured photosensitive resin layer. Examples of the ethylenically unsaturated compound (B) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meta) ) Acrylate, 3-hydroxy-β ′-(meth) acryloyloxyethyl phthalate and other hydroxyl group-containing (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate , Isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, alkyl (meth) acrylate such as stearyl (meth) acrylate, and cycloacrylate such as cyclohexyl (meth) acrylate Halogenated alkyl (meth) acrylates such as kill (meth) acrylate, chloroethyl (meth) acrylate, chloropropyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, etc. Phenoxyalkyl (meth) acrylates such as alkoxyalkyl (meth) acrylate, phenoxyethyl acrylate, nonylphenoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) Alkoxyalkylene glycol (meth) acrylates such as acrylate, (meth) acrylamide, diacetone (meth) acrylate (Meth) acrylamides such as rilamide, N, N′-methylenebis (meth) acrylamide, 2,2-dimethylaminoethyl (meth) acrylate, 2,2-diethylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl Compounds having only one ethylenically unsaturated bond in the molecule such as (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, di (meth) acrylates of polyethylene glycol such as diethylene glycol di (meth) acrylate, Polypropylene glycol di (meth) acrylate such as dipropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra ( Poly (meth) obtained by the addition reaction of an ethylenically unsaturated bond and an active hydrogen compound such as unsaturated carboxylic acid or unsaturated alcohol to acrylate, glycerol tri (meth) acrylate or ethylene glycol diglycidyl ether Examples thereof include compounds having two or more ethylenically unsaturated bonds in the molecule, such as polyvalent (meth) acrylamides such as acrylate and methylenebis (meth) acrylamide, and polyvalent vinyl compounds such as divinylbenzene. Two or more of these may be contained.

  In the photosensitive resin composition of the present invention, the ethylenically unsaturated compound (B) has a polyethylene glycol skeleton in order to obtain high engraving suitability while imparting appropriate flexibility and elasticity to the formed photosensitive resin layer. And a compound (b) having a weight average molecular weight of 400 to 800 having only one ethylenically unsaturated bond in the molecule. Here, the polyethylene glycol skeleton refers to a polymer of tetramer or higher of ethylene glycol. When the ethylenically unsaturated compound has a polyethylene glycol skeleton, the elasticity of the printing plate can be improved. Furthermore, by setting the weight average molecular weight to 400 or more, the flexibility of the formed photosensitive resin layer can be improved, and the flexibility of the printing plate, particularly the flexibility during printing can be improved. On the other hand, when the weight average molecular weight is 800 or less, the functional group density of the formed photosensitive resin layer can be adjusted to an appropriate range, and the engraving suitability of the printing plate can be improved. Moreover, in order to make moderate softness | flexibility and high engraving aptitude compatible, it has only one ethylenically unsaturated bond in a molecule | numerator. In the case of a compound having two or more ethylenically unsaturated bonds in the molecule, since the crosslink density of the photosensitive resin layer is higher than that in the case of only one, the flexibility of the formed photosensitive resin layer is increased. And the flexibility of the printing plate during printing is reduced.

  Specific examples of the compound (b) having a polyethylene glycol skeleton and having only one ethylenically unsaturated bond in the molecule and having a weight average molecular weight of 400 to 800 include polyethylene glycol mono (meth) acrylate and methoxypolyethylene glycol (meta ) Among the alkoxy polyethylene glycol (meth) acrylates such as acrylate and ethoxypolyethylene glycol (meth) acrylate, compounds having a molecular weight falling within the above range may be mentioned.

  Content of the component (B) in the photosensitive resin composition of this invention needs to be 20-65 mass parts with respect to 100 mass parts of said components (A). By setting it as 20 mass parts or more, photocuring of the photosensitive resin layer can be advanced and the engraving suitability of a printing plate can be improved more. On the other hand, by setting it as 65 mass parts or less, the softness | flexibility of the photosensitive resin layer can be improved more and the softness | flexibility of the printing plate at the time of printing can be improved more.

  Furthermore, content of the component (b) in the photosensitive resin composition of this invention needs to be 20-50 mass% among the total mass of a component (B). By setting it as 20 mass% or more, the softness | flexibility of the photosensitive resin layer can be improved and the elasticity of a printing plate and the softness | flexibility at the time of printing can be improved more. On the other hand, when the content is 50% by mass or less, the engraving suitability of the printing plate can be maintained at a high level.

  The photopolymerization initiator (C) 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-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone and the like are preferably used in the present invention.

  The content of the photopolymerization initiator (C) in the photosensitive resin composition of the present invention is 0.3% by mass or more in the photosensitive resin composition from the viewpoint of improving the photopolymerization reactivity of the ethylenically unsaturated compound. Preferably, 0.5 mass% or more is more preferable.

  Moreover, the photosensitive resin composition of this invention may contain a plasticizer in the range which does not impair the above-mentioned function. By containing a plasticizer, the flexibility of the photosensitive resin layer can be further improved, and the flexibility of the printing plate during printing can be further improved. The plasticizer preferably has high compatibility with the component (A). Generally, for hydrophilic polymers such as water-soluble polymers or water-swellable polymers, highly hydrophilic plasticizers have good compatibility. Examples of preferable plasticizers include polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, and trimethylolethane, and ethylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol. . Two or more of these may be contained.

  The content of the plasticizer in the photosensitive resin composition of the present invention is preferably 20 to 65 parts by mass with respect to 100 parts by mass of the component (A) from the viewpoint of flexibility during printing.

  Among the plasticizers, ethylene glycols, particularly tetramer glycol and other tetramer or more compounds, like the component (b) described above, improve the flexibility of the photosensitive resin layer and increase the elasticity of the printing plate. Flexibility during printing can be further improved.

  The photosensitive resin composition of the present invention can contain a known polymerization inhibitor for the purpose of ensuring thermal stability. Preferable polymerization inhibitors include phenols, catechols, hydroquinones, nitrosamines and the like. In order to obtain sufficient photopolymerization reactivity of the photosensitive resin layer, the content of the polymerization inhibitor in the photosensitive resin composition of the present invention is preferably 0.5% by mass or less.

  The photosensitive resin composition of the present invention can contain a surfactant for the purpose of improving the rinsing property of engraving residue and preventing aggregation of the photosensitive resin component in the developer. Examples of the surfactant include nonionic surfactants such as polyoxyalkylenes, anionic surfactants such as sulfonates, sulfates and phosphates, and cationic surfactants such as amines, Zwitterionic surfactants can be exemplified. The content of the surfactant in the photosensitive resin composition of the present invention is preferably 0.001 to 5% by mass from the viewpoint of improving the rinsing property of engraving residue and preventing aggregation of the photosensitive resin component in the developer. More preferably, it is 0.05-3 mass%. When the amount is 0.001 part by mass or more, the water-solubility of the engraving residue is increased and it is possible to easily rinse, and there is an effect of suppressing the aggregation of the resin in the rinsing water. It is possible to maintain a state where bubbles do not easily reach the water.

  The photosensitive resin composition of the present invention further has an antifoaming agent, an ultraviolet absorber, an oxygen scavenger, a sensitizer, and a colorant (dye, pigment, photochromic agent, coloring aid) for the purpose of improving various properties. ), Perfume, deodorant, solvent and the like.

  Next, a method for producing a resin composition for laser engraving of the present invention and a resin printing plate precursor for laser engraving using the same will be described. The resin printing plate precursor for laser engraving of the present invention has at least a support (D) and a photosensitive resin layer (E) formed from the photosensitive resin composition of the present invention.

  As the support (D), a plastic sheet such as polyester, a synthetic rubber sheet such as styrene-butadiene rubber, a metal plate such as steel, stainless steel, and aluminum can be used. Among them, a plastic sheet such as polyester is preferably used from the viewpoint of flexibility, transparency, and dimensional stability, and a sheet of polyethylene terephthalate (hereinafter referred to as PET) is preferable from the viewpoint of heat resistance and chemical resistance.

  The thickness of the support is not particularly limited, but is preferably in the range of 0.10 to 0.35 mm from the viewpoints of handleability and flexibility. If it is 0.10 mm or more, the handleability as a support will be improved, and if it is 0.35 mm or less, the flexibility as a printing original plate will be improved.

  The support (D) is preferably subjected to an easy adhesion treatment for the purpose of improving the adhesion to the photosensitive resin layer (E). Examples of the easy adhesion treatment method include mechanical treatment such as sandblasting, physical treatment such as corona discharge, and chemical treatment such as coating. It is advisable to provide an easy adhesion layer (d1) by coating. It is preferable from the viewpoint.

  The photosensitive resin layer (E) is formed from the photosensitive resin composition of the present invention. The thickness of the photosensitive resin layer (E) is preferably 0.3 mm or more, and more preferably 0.5 mm or more from the viewpoint of having a sufficient relief depth and improving printability.

  The photosensitive printing original plate of the present invention preferably has a cover film (F) on the photosensitive resin layer (E) from the viewpoint of surface protection and prevention of adhesion of foreign matters and the like. The photosensitive resin layer (E) may be in direct contact with the cover film (F), or may have one or more layers between the photosensitive resin layer (E) and the cover film (F). Good. Examples of the layer between the photosensitive resin layer (E) and the cover film (F) include an anti-adhesion layer provided for the purpose of preventing adhesion on the surface of the photosensitive resin layer.

  Although the material of a cover film (F) is not specifically limited, Plastic sheets, such as polyester and polyethylene, are used preferably. Although the thickness of a cover film (F) is not specifically limited, The range of 0.01-0.15 mm is preferable from a viewpoint of handleability and cost. The cover film surface may be smooth or roughened.

  Next, a method for producing a resin printing plate using the resin printing original plate for laser engraving of the present invention will be described. The printing plate of the present invention can be produced through the following steps in sequence.

  That is, it comprises (1) a step of irradiating the printing original plate with actinic rays to crosslink the crosslinkable relief layer, and (2) a step of laser engraving the crosslinked crosslinkable relief layer.

  Furthermore, you may include the following process as needed. Subsequent to step (2), (3) rinsing the engraved surface with water or a liquid containing water as a main component, (4) drying the engraved crosslinkable relief layer, (5) forming a crosslinkable relief layer A step of further crosslinking by irradiation with actinic rays.

  Step (1) is a step of photocuring the resin layer (E), and examples of the active light include visible light, ultraviolet light, and electron beam, and ultraviolet light is the most common. Usually, 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 that can irradiate a wavelength of 300 to 400 nm is used. The step of irradiating actinic rays may be performed before or after the cover film (F) is peeled off if a transparent cover film (F) that transmits actinic rays is provided. Irradiation after peeling. Since polymerization inhibition occurs in the presence of oxygen, the crosslinkable relief layer may be covered with vinyl chloride and evacuated and then irradiated with actinic rays. Further, if the support (D) side of the crosslinkable relief layer is the back surface, the surface may only be irradiated with actinic rays, but if the support (D) is a transparent film that transmits actinic rays, the back surface Can also be irradiated with actinic rays.

  By crosslinking the crosslinkable relief layer, there is an advantage that firstly the relief formed after laser engraving becomes sharp, and secondly, the adhesiveness of engraving residue generated during laser engraving is suppressed. When an uncrosslinked crosslinkable relief layer is laser engraved, unintended portions are easily melted and deformed due to residual heat propagated around the laser irradiated portion, and a sharp relief cannot be obtained. In addition, as a general property of a material, a material having a low molecular weight becomes liquid rather than solid, that is, the adhesiveness becomes strong. The engraving residue generated when engraving the crosslinkable relief layer becomes more tacky as more low molecular weight materials are used. Since the component (B), which is a low molecule, is polymerized by crosslinking, the generated engraving residue tends to be less tacky.

  (2) The step of laser engraving the crosslinkable relief layer is a step of scanning the crosslinkable relief layer by controlling the laser head with a computer based on the digital data of the image to be formed. . When irradiated with an infrared laser, the molecules in the crosslinkable relief layer undergo molecular vibrations and generate heat. When a high-power laser such as a carbon dioxide laser or YAG laser is used as an infrared laser, a large amount of heat is generated in the laser irradiation area, and molecules in the crosslinkable relief layer are selectively removed by molecular cutting or ionization. That is, a sculpture is made. The advantage of laser engraving is that the engraving depth can be set arbitrarily, so that the structure can be controlled three-dimensionally. For example, by engraving with a shallow or shoulder on the part where fine halftone dots are printed, it is possible to prevent the relief from falling down due to printing pressure, and deeply engrave the part of the groove where fine cut characters are printed. Therefore, it becomes difficult for the ink to be buried in the groove, and it is possible to suppress the crushing of the extracted characters.

  When the engraving residue adheres to the engraving surface, a step (3) of rinsing the engraving surface with water or a liquid containing water as a main component and washing away the engraving residue may be added. As a means of rinsing, a method of rinsing with running water, a method of spraying high-pressure water, a batch type or conveying type brush type washing machine known as a photosensitive resin letterpress developing machine, the engraving surface mainly in the presence of water For example, when the engraving residue cannot be removed, a rinsing solution to which soap is added may be used.

  When the step (3) of rinsing the engraved surface is performed, it is preferable to add a step (4) of drying the engraved crosslinkable relief layer and volatilizing the rinse liquid.

  Furthermore, you may add the process (5) which further bridge | crosslinks a crosslinkable relief layer as needed. By performing the additional crosslinking step (5), the relief formed by engraving can be further strengthened.

The photosensitive resin layer in the printing plate of the present invention preferably has a durometer hardness of 75 ° or less measured by a method described later. The durometer hardness of the photosensitive resin layer is an index indicating the flexibility of the printing plate, and if the durometer hardness is 80 ° or less, it is possible to suppress ink imperfection in the solid portion and halftone dot unevenness to some extent, It has been found that a lower durometer hardness is required depending on the printing paper material and printing conditions. When durometer hardness is 75 ° or less, when long-run printing of several thousand meters or more is performed at high speed using art paper which is generally said to be liable to cause ink imperfection in the solid part during printing In this case, it is possible to easily obtain a high-quality printed matter with good ink fillability. Further, since the printing pressure itself can be set low, it is difficult for characters and halftone dots to occur, and the selection of printing conditions is facilitated and workability is improved.
In addition, since the hardness is sufficiently soft even when it is reused, it does not float or peel off from the cylinder, and the ink inking property is maintained.

  The durometer hardness of the photosensitive resin layer can be measured by the following method. The whole surface is exposed under vacuum under the condition of a gray scale sensitivity of 16 ± 1 with an ultraviolet low pressure mercury lamp, the photosensitive resin layer is peeled off from the printing plate, and left at room temperature of 20 ° C. and humidity of 65% for 24 hours. The photosensitive resin layer after being allowed to stand is overlapped with a thickness of 5 mm to 6 mm, and the durometer hardness is measured by a method defined in JIS K6253-3 (2012) using a type A durometer.

  A printing plate produced using the resin printing original plate for laser engraving of the present invention has both high engraving suitability and flexibility, and is most suitable for flexographic printing and form printing. It can also be used for press printing, lithographic printing, intaglio printing, stencil printing, and photoresist.

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

Synthesis Example 1 Modification of Partially Saponified Polyvinyl Acetate Partially saponified polyvinyl acetate “J Poval JR-05” (polymerization degree: about 800, saponification degree: 72 mol%) manufactured by Nippon Vinyl Beverage Poval Co., Ltd. The mixture was swollen in, 1.0 mol% of succinic anhydride was added, and the mixture was stirred at 60 ° C. for 6 hours to add a carboxyl group to the molecular chain. The polymer was washed with acetone to remove unreacted succinic anhydride and dried. The acid value was measured and found to be 10.8.

Synthesis Example 2: Synthesis of polyamide 60 parts by mass of an equimolar salt of α, ω-diaminopolyoxyethylene and adipic acid obtained by adding acrylonitrile to both ends of polyethylene glycol having a number average molecular weight of 600 and reducing this with hydrogen, 20 parts by mass of ε-caprolactam and 20 parts by mass of an equimolar salt of hexamethylenediamine and adipic acid were melt-polymerized and the relative viscosity (1 g of polymer was dissolved in 100 ml of chloral hydrate and measured at 25 ° C.) was 2.50. Polyamide was obtained.

<Preparation of Support (D) Having Easy Adhesive Layer (d1)>
"Byron" (registered trademark) 31SS (toluene solution of unsaturated polyester resin, manufactured by Toyobo Co., Ltd.) 260 important parts and "PS-8A" (benzoin ethyl ether, manufactured by Wako Pure Chemical Industries, Ltd.) 2 mass Part of the mixture was heated at 70 ° C. for 2 hours and then cooled to 30 ° C., and 7 parts by mass of ethylene glycol diglycidyl ether dimethacrylate was added and mixed for 2 hours. Furthermore, 25 parts by mass of “Coronate” (registered trademark) 3015E (ethyl acetate solution of polyvalent isocyanate resin, manufactured by Nippon Polyurethane Industry Co., Ltd.) and “EC-1368” (industrial adhesive, manufactured by Sumitomo 3M Co., Ltd.) 14 parts by mass was added and mixed to obtain an easy-adhesion layer (d1) coating solution 1.

  50 parts by weight of “Gohsenol” (registered trademark) KH-17 (polyvinyl alcohol having a saponification degree of 78.5 to 81.5 mol%, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was added to “Solmix” (registered trademark) H— 11 (alcohol mixture, manufactured by Nippon Alcohol Co., Ltd.) in a mixed solvent of 200 parts by mass and 200 parts by mass of water at 70 ° C. for 2 hours, then “Blenmer” (registered trademark) G (glycidyl methacrylate, Nippon Oil & Fats Co., Ltd.) 1.5 parts by mass of the product), and mixed for 1 hour. Further, a copolymer of 2/1 (dimethylaminoethyl methacrylate) / (2-hydroxyethyl methacrylate) mass ratio (manufactured by Kyoeisha Chemical Co., Ltd.) 3 mass Part, 2,2-dimethoxy-2-phenylacetophenone, 5 parts by weight, “epoxy ester 70PA” (propylene glycol diglycidyl ether 21 parts by mass of a phosphoric acid adduct (manufactured by Kyoeisha Chemical Co., Ltd.) and 20 parts by mass of ethylene glycol diglycidyl ether dimethacrylate were added and mixed for 90 minutes. After cooling to 50 ° C., “FLORARD ™ FC-430” (fluorine) 0.1 part by mass of a system surfactant (manufactured by Sumitomo 3M Co., Ltd.) was added and mixed for 30 minutes to obtain a coating solution 2 for an easy adhesion layer (d1).

  Bar coater so that the film thickness becomes 40 μm after drying coating liquid 1 for easy adhesion layer (d1) on “Lumirror” (registered trademark) T60 (polyester film, manufactured by Toray Industries, Inc.) having a thickness of 0.18 mm. After removing the solvent by heating in an oven at 180 ° C. for 3 minutes, the coating liquid 2 for the easy adhesion layer (d1) is applied thereon with a bar coater so that the dry film thickness is 30 μm. It heated for 3 minutes in 160 degreeC oven, and obtained the support body (D) which has an easily bonding layer (d1).

<Preparation of cover film (G)>
To “Lumirror” S10 (polyester film, manufactured by Toray Industries, Inc.) having a thickness of 0.10 mm roughened to have a surface roughness Ra of 0.1 to 0.6 μm, “GOHSENOL” AL-06 ( A partially saponified polyvinyl alcohol having a saponification degree of 91 to 94 mol% (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was applied to a dry film thickness of 1 μm, dried at 100 ° C. for 25 seconds, and an analog version cover Film G1 was obtained.

[Evaluation method]
Evaluation in each example and comparative example was performed by the following method.

(1) Flexibility A plate making apparatus DX-A3 (Takano) equipped with a chemical lamp FL20SBL-360 20 watts (manufactured by Mitsubishi Electric OSRAM Co., Ltd.) by peeling the polyester film of the cover film G from a 10 cm × 10 cm photosensitive printing original plate (Made by Co., Ltd.), and the whole surface was exposed in the atmosphere (exposure amount: 2400 mJ / cm ² ) to prepare a printing plate for hardness evaluation. Then, the durometer hardness was measured by the method prescribed | regulated to JISK6253-3 (2012) using the type A durometer.

(2) Engraving suitability A plate making apparatus DX-A3 (manufactured by Takano Co., Ltd.) equipped with a chemical lamp FL20SBL-360 20 Watts (manufactured by Mitsubishi Electric OSRAM Co., Ltd.) from the cover film (I) side of the laser engraving printing original plate Then, the entire surface was exposed in the atmosphere (exposure amount: 2400 mJ / cm ² ). Only the polyester film of the cover film (I) is peeled off, and laser engraving (Engraving speed: 600 cm / s, Pitch: 10 μm, Top: 8%, Bottom: 100%, Width: Adflex Direct 250L (manufactured by Comtex Co., Ltd.) 0.3 mm).

Then, it rinsed for 20 second with 25 degreeC tap water using plate-making apparatus DX-A3, and dried for 10 minutes with a 60 degreeC hot air dryer. The whole plate was exposed again in the atmosphere with a chemical lamp (exposure amount: 2400 mJ / cm ² ) to obtain a printing plate.

About the obtained printing plate, the remaining engraving residue after rinsing was confirmed with a 25-fold magnifier, the relief depth was measured with a Mitsutoyo Thickness Gauge, and the shape of the halftone dot was confirmed with a 25-fold magnifier. Since the relief depth is engraved with the same laser energy at all levels, the deeper the depth, the higher the engraving speed, and the longer the engraving takes. The halftone dot shape was confirmed to be a halftone dot shape that should be obtained under the engraving conditions without the distortion of the halftone dot. The halftone dots were observed from the apex side, and when the shape was circular, it was determined to be acceptable, when it was distorted into an ellipse, or when it was missing, it was determined to be unacceptable.
(3) Printability The printing plates obtained in each of the examples and comparative examples were evaluated using a flexographic printing machine (MP560 manufactured by MPS). The cylinder of the printing machine has a circumference of 356 mm, the anilox roll has a line number of 400 LPcm (cell volume 4.2 ml / m ² ), the ink uses flexographic ink (UV flexo process red PHA-L03 manufactured by T & K TOKA), and the speed is 60 m. Printed at / min. Cushion tape (52017 manufactured by Tesa Tape Co., Ltd.) having a thickness of 0.38 mm was used for attaching the printing plate to the plate cylinder. The printing pressure is as low as possible for each printing plate (this is the minimum printing pressure where ink fills the entire solid area and characters and halftone dots are not clearly thickened. Since high printing pressure is required, it is necessary to adjust the printing pressure appropriately for each printing plate). As the paper type, cast coated paper (manufactured by Oji Tac Co., Ltd., N mirror 73 P22 G8B) and art paper (manufactured by Lintec Co., Ltd., Art PW 8K) are used. The part (5 cm × 5 cm) was observed visually and using a magnifying glass with a magnification of 20 times to determine whether the ink deposition property was good or bad. When the adhesiveness of the printing plate surface is high and when the ink plate has poor ink depositability, a phenomenon is observed in which the ink is unevenly deposited on the printing plate and ink loss occurs in the solid portion of the printed matter. Evaluation was performed according to the following evaluation criteria.
○: 50 to 100 μm ink loss on the printed matter is 5 cm × 5 cm and 3 or less Δ: 50 to 100 μm ink loss is 5 cm × 5 cm to 4 to 10 ××: 50 to 100 μm ink loss is 5 cm on the printed matter × 5 cm is more than 10 pieces.

  Next, assuming that the printing plate is reused, the plate used in the above printing is stored together with silica gel in a desiccator at 20 ° C. for 72 hours, and art paper is used in the same manner as above using the printing plate. Ink solidity evaluation of the solid part of the printed material was performed, and the reusability of the printing plate was evaluated.

  The raw materials used in each example and comparative example are shown below. In the table, PEG represents polyethylene glycol.

Example 1
Add water-soluble polymer or water-swellable polymer and plasticizer shown in Table 2 to a mixed solvent of water / ethanol ratio 55/45 (mass ratio) according to the contents of Table 2, and dissolve by stirring at 70 ° C. for 2 hours. I let you. Next, glycidyl methacrylate (“Blenmer” G manufactured by NOF Corporation) was added according to the content of Table 2, and the mixture was stirred at 70 ° C. for 0.5 hour. Furthermore, various ethylenically unsaturated compounds, photopolymerization initiators, and additives (dyes, polymerization inhibitors, ultraviolet absorbers) shown in Table 2 were added according to the contents in Table 2, and stirred at 70 ° C. for 0.5 hour. Thus, a photosensitive resin composition solution was obtained. At this time, the solid content concentration of the photosensitive resin composition solution was adjusted to 60 mass%. When the solution was visually confirmed, no separation or turbidity of the solution was observed, and the solution was uniform.

  The obtained photosensitive resin composition solution was cast on the support (D) having the easy-adhesion layer (d1) and dried at 60 ° C. for 2.5 hours. At this time, the plate thickness after drying (polyester film + photosensitive resin layer) was adjusted to 1.14 mm. On the photosensitive resin layer thus obtained, a mixed solvent of water / ethanol = 50/50 (mass ratio) was applied, and a cover film (G1) was pressure-bonded to the surface to obtain a photosensitive printing original plate. . Table 3 shows the results of evaluating the characteristics of the printing plate by the above method using the obtained photosensitive printing original plate. The printing plate had a durometer hardness of 75 ° or less.

(Examples 2-6, Comparative Examples 1-6)
A resin sheet and a printing original plate were produced in the same manner as in Example 1 except that the composition of the resin composition was changed as shown in Table 2. The evaluation results are shown in Table 3.

Claims (5)

A support and a resin layer on the support, the resin layer,
(A) a water-soluble polymer or a water-swellable polymer, (B) an ethylenically unsaturated compound,
(C) A compound (b) having a molecular weight of 400 to 800, which contains a photopolymerization initiator and the ethylenically unsaturated compound (B) has a polyethylene glycol skeleton and has only one ethylenically unsaturated bond in the molecule. A resin printing plate precursor for laser engraving, which is a photosensitive resin composition comprising: 20-65 mass parts of said components (B) are contained with respect to 100 mass parts of said components (A), and content of the said compound (b) is 20-50 mass% with respect to the said component (B). The resin printing plate precursor for laser engraving according to claim 1. A resin printing plate crosslinked precursor for laser engraving obtained by crosslinking the resin printing plate precursor for laser engraving according to claim 1. 3. A step of crosslinking the resin printing plate precursor for laser engraving according to claim 1 or 2 to obtain a resin printing plate crosslinked precursor for laser engraving, and irradiating the crosslinked precursor with a pattern to engrave the resin layer to obtain a relief. A method for producing a printing plate comprising steps. The manufacturing method of the printing plate which has the process of rinsing a relief with the liquid containing water or water after the process of Claim 4.