JP2008229875A - Flexographic printing original plate and manufacturing method of flexographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexographic printing original plate which has an excellent elasticity and enables easy removal of residue by washing with water after laser engraving. <P>SOLUTION: The flexographic printing original plate is constituted by stacking (A) a substrate layer, (B) a resin layer formed of an elastomeric binder and an elastomeric composition containing a crosslinking agent capable of crosslinking the elastomeric binder and (C) a hydrophilic resin layer. Even when the resin layer is cured by exposure or heating and subjected to laser engraving, according to this flexographic printing original plate, the residue of the resin layer after the layer is cured can be easily removed, Besides, an edge portion is not rounded and a dot gain due to printing is not enlarged, in the upper part of the flexographic printing plate after laser engraving. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flexographic printing plate used for producing a flexographic printing plate and a method for producing a flexographic printing plate.

  In flexographic printing, printing using various inks such as water-based ink, UV ink, and solvent ink can be performed. However, in recent years, flexographic printing using water-based ink has attracted attention from the viewpoint of environmental safety. Yes. As a flexographic printing plate that is a precursor material for obtaining a relief plate for flexographic printing, a flexographic printing plate provided with a photosensitive resin composition layer is widely known. Regarding the preparation of flexographic printing plates, a method of developing a photosensitive resin composition layer in a flexographic printing original plate using a lithography technique, a method of directly engraving a cured flexographic printing original plate with a laser, and the like have been developed. ing. In the method of creating a flexographic printing original plate using laser engraving, the digitized image data can be corrected only on a computer, so that time can be saved and labor can be reduced.

  Among them, as a method for producing a flexographic printing plate by laser engraving, Patent Document 1 describes (a) an elastomer layer on the top of a flexible support, a mechanical method, an optical method, and a thermochemical method. To create a laser-engravable flexographic element having a cover sheet removable on top of this elastomer layer, if necessary, and (b) after removing the cover sheet, Disclosed is a method for producing a single-layer flexographic printing plate, wherein a laser-engraved flexographic printing element of a) is laser engraved according to at least one preselected pattern to create a laser engraved flexographic printing plate ing.

Patent Document 2 discloses a hydrophilic polymer (A1) containing hydroxyethylene as a structural unit, a hydrophilic polymer (A2) other than (A1), an ethylenically unsaturated monomer (B), a polymerization initiator (C), and A crosslinkable resin composition for laser engraving characterized by containing a plasticizer (D) is disclosed. According to the invention described in Patent Document 2, a relief printing plate having suitability for both resin relief printing and flexographic printing can be easily provided.
Japanese National Patent Publication No. 7-506780 JP 2006-002061 A

  However, as can be seen in the method for producing a single-layer flexographic printing plate described in Patent Document 1, an elastomer layer is generally provided on the top of the flexographic printing plate. A laser is applied to melt and remove the elastomeric material locally. In this case, a large amount of residue remained at the laser irradiation site, and it was necessary to remove it. Here, since the elastomer material is generally insoluble in water, removal of the residue after laser irradiation requires much cost and labor, such as being immersed in a detergent and then washed with high pressure.

  On the other hand, as in the invention described in Patent Document 2, a printing plate for laser engraving that can be washed with water produced from a hydrophilic polymer has been developed. However, such a printing plate has a hydrophilic polymer layer. Since the hardness was too high, it was not suitable for actual flexographic printing.

  The present invention has been made in view of the problems as described above, and has an object to provide a flexographic printing plate having excellent elasticity and capable of easily removing a residue by washing with water after laser engraving. To do.

  The present inventors have conducted intensive studies in view of the above problems. As a result, the present inventors have found that the above problems can be solved in a flexographic printing original plate obtained by laminating a support layer, a resin layer, and a hydrophilic resin layer, and have completed the present invention.

  Specifically, the present invention provides the following.

  The first aspect of the present invention includes (A) a support layer, (B) an elastomeric binder, and a resin layer formed from an elastomeric composition containing a crosslinking agent capable of crosslinking the elastomeric binder, and ( C) A flexographic printing original plate obtained by laminating a hydrophilic resin layer.

  The second aspect of the present invention includes a step of curing the resin layer by irradiating the flexographic printing original plate of the first aspect with an actinic ray or performing a heat treatment, and the cured resin layer, The production of a flexographic printing plate comprising: a step of laser engraving by laser irradiation from the hydrophilic resin layer side; and a step of removing the residue and the hydrophilic resin layer generated by laser engraving by water washing Is the method.

  According to the present invention, since the resin layer contains an elastomeric binder, the resin layer exhibits excellent elasticity. Moreover, since the hydrophilic resin layer is laminated on the resin layer, the resin layer is cured by exposure or heat treatment, and even after laser engraving, the residue of the cured fat layer can be easily removed. it can. Further, the edge portion is not rounded at the upper part of the flexographic printing plate after laser engraving, and the dot gain by printing does not increase.

  Hereinafter, embodiments of the present invention will be described in detail.

<Flexographic printing master>
The flexographic printing original plate according to the present embodiment includes (A) a support layer, (B) an elastomeric binder, and a resin layer formed from an elastomeric composition containing a crosslinking agent capable of crosslinking the elastomeric binder, and (C) A hydrophilic resin layer is laminated.

[(A) Support layer]
The support layer used for the flexographic printing plate according to the present embodiment is conventionally used as a support for a flexographic printing plate, and satisfies mechanical strength and physical properties suitable for various printing conditions. It can be formed by arbitrarily selecting from materials such as metal sheets, plastic films, paper and composites thereof. Examples of such materials include polymeric films formed from addition polymerized polymers and linear condensation polymers; foams; woven fabrics such as glass fiber fabrics and nonwoven fabrics; and metals such as steel and aluminum. Can be mentioned. Examples of such a support include polyethylene or polyester film, and particularly preferable is a polyethylene terephthalate film. The support layer is usually formed into a film or sheet having a thickness of 50 μm to 300 μm, preferably 75 μm to 200 μm.

  The support layer may also have a thin adhesion promoting layer between the resin layer, if necessary. As this adhesion promotion layer, the layer which consists of a mixture of an acrylic resin and polyisocyanate can be mentioned, for example.

[(B) Resin layer]
The resin layer is formed from an elastomeric composition containing an elastomeric binder and a crosslinking agent capable of crosslinking the elastomeric binder.

(Elastomeric binder)
Examples of the elastomeric binder include styrene / butadiene resins; styrene / isoprene resins; polydiolefins such as polybutadiene and polyisoprene; vinyl aromatic compound / diolefin random copolymers and block copolymers; diolefin / acrylonitrile. Copolymer; ethylene / propylene copolymer; ethylene / propylene / diolefin copolymer; ethylene / acrylic acid copolymer; diolefin / acrylic acid copolymer; diolefin / acrylic acid ester / acrylic acid copolymer Ethylene / (meth) acrylic acid / (meth) acrylic ester copolymer; polyamide; polyvinyl alcohol; graft copolymer of polyvinyl alcohol and polyethylene glycol; amphoteric interpolymer; alkyl cellulose, hydride Celluloses such as xyalkyl cellulose and nitrocellulose; copolymer of ethylene and vinyl acetate; cellulose acetate butyrate; polybutyral; cyclic rubber; copolymer of styrene and acrylic acid; polyvinyl pyrrolidone; Examples thereof include a copolymer with vinyl acetate. These elastomeric binders may be used alone or in combination of two or more.

(Crosslinking agent capable of crosslinking elastomeric binder)
As the crosslinking agent capable of crosslinking the elastomeric binder, a known material as a photosensitive material for producing a flexographic printing plate can be used. For example, the crosslinking agents disclosed in U.S. Pat. Nos. 4,323,636, 4,753865, 4,726,877, and 4,894,315 can be mentioned, and any of these can be selected. Can be used.

  Examples of such crosslinking agents include, for example, ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, triethylene glycol Methylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol Triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diac Rate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, acrylic ester such as polyester acrylate oligomer, and corresponding methacrylic acid Esters; ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate, and sorbitol tetra Itaconic acid esters such as itaconate; ethylene glycol dicrotonate, tetramethylene glycol Crotonic acid esters such as ethylene dichromate, pentaerythritol dicrotonate, sorbitol tetradicrotonate, ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate; Maleates such as ethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate; and methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis Unsaturation such as methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, and xylylene bismethacrylamide Examples thereof include carboxylic acid amides.

  Such a crosslinking agent is used in an amount of 5 to 100 parts by weight, preferably 10 to 80 parts by weight, based on 100 parts by weight of the elastomeric binder. By making the compounding quantity of a crosslinking agent into the said range, the film property of a resin layer does not deteriorate, and it can maintain high adhesiveness with a support body layer and the hydrophilic resin layer mentioned later.

  Furthermore, it is preferable to mix a photoinitiator and / or a thermal polymerization initiator in the elastomeric composition for forming the resin layer. Such photoinitiators include aromatic ketones such as benzophenone; benzoin methylcellulose, benzoin ethyl ether, benzoin propyl ether, α-methylol benzoin methyl ether, α-methoxybenzoin methyl ether, 2,2-diethoxyphenyl. Examples thereof include benzoin ethers such as acetophenone. These may be used alone or in admixture of two or more. In addition, substituted and unsubstituted polynuclear quinones disclosed in, for example, US Pat. Nos. 4,460,675 and 4,894,315 can also be used.

  In addition, examples of the thermal polymerization initiator include organic peroxides, hydroperoxides, and azo compounds. Specifically, t-butyl peroctanoate, t-amyl peroctanoate, t-butyl peroxyisobutyrate, t-butyl peroxymaleate, t-amyl perbenzoate, di-t-butyl diperoxyphthalate, Peroxyesters such as t-butyl perbenzoate, t-butyl peracetate, and 2,5-di (benzoylperoxy) -2,5-dimethylhexane; 1,1-di (t-amylperoxy) cyclohexane, 1 Diperoxyketals such as 1,2-di (t-butylperoxy) cyclohexane, 2,2-di (t-butylperoxy) butane, and ethyl-3,3-di (t-butylperoxy) butyrate; Oxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, and 2,5-di (t-butyl) Alkyl peroxides such as ruperoxy) -2,5-dimethylhexane; diacyl peroxides such as benzoyl peroxide, dibenzoyl peroxide, and diacetyl peroxide; t-butyl hydroperoxide, t-amyl hydroperoxide, pinane hydroperoxide, and T-alkyl hydroperoxides such as milhydroperoxide; and 1- (t-butylazo) formamide, 2- (t-butylazo) isobutyronitrile, 1- (t-butylazo) cyclohexanecarbonitrile, 2- (t- Butylazo) -2-methylbutanenitrile, 2,2′-azobis (2-acetoxypropane), 1,1′-azobis (cyclohexanecarbonitrile), 2,2′-azobis (isobutyronitrile), and 2, 2 ' Azobis (2-methylbutane nitrile) azo compounds such like. Among these, dilauroyl peroxide is particularly preferable.

  Such a photoinitiator and / or thermal polymerization initiator is 0.5% by mass or more and 50% by mass or less, preferably 3% by mass or more and 35% by mass or less, with respect to the total mass of each composition constituting the resin layer. In such a range, it can be appropriately blended.

  Furthermore, it is preferable to add a plasticizer to the elastomeric composition for forming the resin layer. Such plasticizers include olefinic, paraffinic, naphthenic, or aromatic mineral oils. Among these, olefin plasticizers such as 1,2-butadiene, 1,4-butadiene, and isoprene are preferable.

  Such a plasticizer is appropriately blended in the range of 0.5% by mass or more and 50% by mass or less, preferably 3% by mass or more and 35% by mass or less, with respect to the total mass of each composition constituting the resin layer. be able to.

(Other ingredients)
In the present embodiment, if necessary, the elastomeric composition includes a polymerization inhibitor such as hydroquinone and hydroquinone monoethyl ether; an antifoaming agent such as a silicone-based antifoaming agent and a fluorine-based antifoaming agent; Surfactants such as surfactants, cationic surfactants, and nonionic surfactants; matting agents such as silica; sensitizers; colorants; and infrared absorbers and other commonly used additives Can be contained. Moreover, when forming a resin layer into a film from an elastomeric composition, a solvent can be contained in the elastomeric composition.

(Infrared absorber)
The infrared absorbing agent absorbs infrared rays irradiated during laser engraving, generates heat, and plays a role of melting and removing the resin layer. Since the elastomeric binder contained in the resin layer originally absorbs infrared rays, the infrared absorber added to the resin layer is an optional additive component and may not be added. The infrared absorber is not particularly limited as long as it absorbs infrared laser light. For example, black pigments such as carbon black, aniline black, and cyanine black; phthalocyanine pigments, naphthalocyanine pigments, and the like Green pigments: graphite, iron powder, diamine-based metal complexes, dithiol-based metal complexes, phenolthiol-based metal complexes, mercaptophenol-based metal complexes, crystal water-containing inorganic compounds, copper sulfate, and chromium sulfide; silicate chloride, oxidation Metal oxides such as chromium, titanium oxide, vanadium oxide, manganese oxide, iron oxide, tungsten oxide, and hydroxides and sulfates of these metals; and metal powders such as bismuth, iron, magnesium, and aluminum Used. Among these, carbon black is preferable from the viewpoints of photothermal conversion efficiency, economy, and handleability.

(solvent)
The solvent is used when the components contained in the resin layer containing the elastomeric binder are dissolved and applied uniformly on the support layer. As the solvent for dissolving the components contained in the resin layer, ether solvents, hydrocarbon solvents, aromatic hydrocarbon solvents, ester solvents, and ketone solvents can be preferably used. Specifically, dibutyl ether, isopropyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate , Propylene glycol monoethyl ether acetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate, 4-methoxybutyl acetate, 2-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-ethyl- 3-methoxybutyl acetate, 2-ethoxybutyl acetate 4-ethoxybutyl acetate, 4-propyloxybutyl acetate, 2-methoxypentyl acetate, chloroform, tetrachloroethylene, benzene, toluene, xylene, ethyl acetate, n-propyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, acetone, Diethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, cyclohexanone and the like are preferable.

[(C) hydrophilic resin layer]
The flexographic printing original plate according to the present embodiment has a hydrophilic resin layer mainly composed of a non-crosslinked hydrophilic resin in an upper layer of the resin layer. By laminating a hydrophilic resin layer containing a hydrophilic resin on the resin layer, the residue can be easily washed away only by washing with water when the resin layer after crosslinking is laser engraved.

(Hydrophilic resin)
The hydrophilic resin that can be contained in the hydrophilic resin layer is not particularly limited, and examples thereof include vinyl polymers and amide polymers. Of these, vinyl polymers can be preferably used. The hydrophilic resin contained in the hydrophilic resin layer preferably has a difference between the melting point and the thermal decomposition starting temperature of 1 ° C. or higher and 200 ° C. or lower. Within this range, a large amount of the edge portion is not melted in the laser engraving, and the edge portion of the resin layer is not rounded.

  In the present specification, the vinyl polymer refers to a polymer obtained from a vinyl compound, and examples thereof include polyvinyl pyrrolidone, polyvinyl alcohol, and polyvinyl butyral. Among these, polyvinyl alcohol is particularly preferable because it has a high degree of hydrophilicity.

  When polyvinyl alcohol obtained by saponifying polyvinyl acetate is used as the hydrophilic resin, the saponification degree of polyvinyl acetate is preferably 50 mol% or more, and more preferably 65 mol% or more. When the degree of saponification is 50 mol% or more, sufficient hydrophilicity can be imparted to the hydrophilic resin layer.

  Moreover, when forming a hydrophilic resin layer into a film from a hydrophilic resin composition, a solvent can be contained. As such a solvent that can be added to the hydrophilic resin layer, water alone or a mixed solvent of water and an alcohol solvent can be used. Examples of such alcohol solvents include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, and 2,3-butylene. A glycol etc. can be mentioned. These alcohol solvents are used by mixing up to 50% by mass with respect to water.

<Method for producing flexographic printing plate>
The manufacturing method of the flexographic printing plate according to the present embodiment includes: (A) a support layer, (B) a resin layer, and (C) a hydrophilic resin layer that are sequentially laminated to produce a flexographic printing plate, and this flexographic printing plate The resin layer is cured by irradiating actinic rays or heat treatment, and the cured resin layer is laser-engraved by laser irradiation from the hydrophilic resin layer side. It is manufactured by removing the hydrophilic resin layer by washing with water.

[Preparation of flexographic printing plate]
The flexographic printing original plate is produced by sequentially laminating a resin layer and a hydrophilic resin layer on a support layer. The method for laminating the resin layer and the hydrophilic resin layer on the support layer is not particularly limited, and any method can be selected from methods commonly used for laminating the resin layer on the support. it can. As such a method, for example, each component of the resin layer or the hydrophilic resin layer is mixed at a predetermined ratio, dissolved in an appropriate solvent, cast into a mold and evaporated, and the layer is left as it is. And a method in which each component is kneaded with a kneader or a roll mill without using a solvent, and formed into a predetermined thickness by an extruder, an injection molding machine, a press, or the like. The thickness of the resin layer is preferably 0.1 mm or more and 3.0 mm or less, and more preferably 0.5 mm or more and 2.0 mm or less. The thickness of the hydrophilic resin layer is preferably 3 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[Irradiation of active ray to flexographic printing plate or heat treatment]
After producing the flexographic printing original plate, the front surface of the flexographic printing original plate is irradiated with active rays or subjected to heat treatment, and the elastomeric binder contained in the resin layer is crosslinked with a crosslinking agent. Thereby, the resin layer is cured, and a resin layer having sufficient strength to withstand flexographic printing is formed. As the active ray irradiated to the resin layer, for example, an active ray having a wavelength of 150 nm or more and 600 nm or less can be preferably used. The wavelength is more preferably from 300 nm to 400 nm. As such an active light source, a high-pressure mercury lamp, a carbon arc lamp, a xenon lamp, or the like can be used. In order to sufficiently cure the resin layer, active rays may be irradiated from both the hydrophilic resin layer side and the support layer side of the flexographic printing original plate. Moreover, as said heat processing, the heat processing in a high temperature oven, the high temperature press method, etc. are mentioned.

[Laser engraving]
In laser engraving, an image to be formed is input to a computer as digital data, a laser apparatus is controlled from the computer, and laser light is irradiated from the hydrophilic resin layer side to obtain a flexographic printing plate having a desired pattern. As a laser used for laser engraving, any laser having a wavelength that is absorbed by a crosslinked resin layer may be used. In general, an infrared laser having a wavelength of 830 μm or more and 20,000 μm or less is used. Can be used. Examples of such a laser include a carbon dioxide laser, a YAG laser, and a semiconductor laser. A carbon dioxide laser having a wavelength of 106,000 μm is particularly preferable.

[Washing of residue and hydrophilic resin layer]
In the method of manufacturing a flexographic printing plate according to the present embodiment, the flexographic printing plate is washed after laser engraving. Thereby, the residue generated when engraving the resin layer can be removed together with the hydrophilic resin layer laminated on the upper layer of the resin layer. The flexographic printing plate can be washed with an aqueous solution containing a solvent or a surfactant. However, when the flexographic printing plate is produced using the flexographic printing plate according to this embodiment, it is sufficient to use only water. Cleansing is possible. Since the cleaning liquid for cleaning the flexographic printing plate is water, it becomes easy to process the waste liquid after cleaning, the cost required for the waste liquid processing can be suppressed, and the burden on the environment can be suppressed low. Examples of the method for washing the flexographic printing plate include high-pressure spray washing and brush washing.

<Formation of resin layer 1>
100 parts by mass of a styrene-butadiene copolymer (trade name: D-1155, manufactured by JSR Kraton Elastomer Co., Ltd.) as a thermoplastic elastomeric binder and 40 masses of liquid polybutadiene (trade name: Nisso PB-2000, manufactured by Nippon Soda Co., Ltd.) Parts, 10 parts by weight of trimethylolpropane triacrylate, 3 parts by weight of methoxyphenylacetophenone, 0.05 parts by weight of 2,6-di-tert-butyl-4-hydroxytoluene, Oil Blue # 503 (Orient Chemical Co., Ltd.) Elastomeric composition 1 was prepared by dissolving 0.002 parts by mass in a solvent comprising 0.2 parts by mass of tetrahydrofuran. While kneading this elastomeric composition 1 in an extruder with a high viscosity pump, the elastomeric composition 1 is extruded to a thickness of 1.7 mm onto an adhesive layer coated on a support made of a polyethylene terephthalate sheet, and the resin layer 1 Got.

<Formation of resin layer 2>
100 parts by mass of a styrene butadiene copolymer (trade name: D-1155, manufactured by JSR Kraton Elastomer Co., Ltd.) as a thermoplastic elastomeric binder and 40 masses of liquid polybutadiene (trade name: Nisso PB-2000, manufactured by Nippon Soda Co., Ltd.) Part, 10 parts by mass of trimethylolpropane triacrylate, 2 parts by mass of di-t-butyl peroxide, 0.002 parts by mass of oil blue # 503 (manufactured by Orient Chemical Co., Ltd.), toluene / MEK (2: 1) Elastomeric composition 2 was prepared by dissolving in a solvent consisting of 150 parts by mass. The elastomeric composition 2 was extruded to a thickness of 1.7 mm on an adhesive layer applied on a support made of a polyethylene terephthalate sheet while kneading in an extruder with a high viscosity pump, and the resin layer 2 Got.

<Example 1>
20 parts by mass of “PVA505C” (trade name, polyvinyl alcohol, saponification degree 73 mol%, manufactured by Kuraray Co., Ltd.) was dissolved in 100 parts by mass of a water / methanol mixed solvent (mass mixing ratio = water: methanol = 3: 1), It was applied on the resin layer 1. This was heated in an oven at 65 ° C. to remove the solvent to obtain a flexographic printing plate having a hydrophilic resin layer having a thickness of 4 μm.

  The above flexographic printing plate precursor is subjected to an entire surface exposure treatment for 10 minutes, the resin layer 1 is cured, and subsequently an output of 250 using a “ZED MINI (device name)” (carbon dioxide laser device, manufactured by Lusha). Laser engraving with Watt. The flexographic printing plate after laser engraving was washed with water to form a flexographic printing plate.

<Example 2>
A flexographic printing original plate was obtained in the same manner as in Example 1 except that the resin layer 1 was changed to the resin layer 2.

  The flexographic printing original plate is subjected to a heat treatment in an oven at 150 ° C. for 20 minutes to cure the resin layer 2, and then “ZED MINI (device name)” (carbon dioxide laser device, manufactured by Lusha). Was used for laser engraving at an output of 250 watts. The flexographic printing plate after laser engraving was washed with water to form a flexographic printing plate.

<Comparative Example 1>
The laminate having the resin layer 1 (before forming the water-soluble resin layer) is used as it is as a flexographic printing original plate, subjected to an entire surface exposure treatment for 10 minutes, the resin layer 1 is cured, and subsequently “ZED MINI (device name)”. Laser engraving was performed at an output of 250 watts using a carbon dioxide laser device (manufactured by Lusha). The flexographic printing plate after laser engraving was washed with water to form a flexographic printing plate.

<Comparative example 2>
30 parts by mass of Dianal BR102 (acrylic resin manufactured by Mitsubishi Rayon Co., Ltd.), which is a water-insoluble resin, was dissolved in 100 parts by mass of toluene and applied onto the resin layer 2. This was dried in an oven at 65 ° C. to remove the solvent and obtain a flexographic printing original plate having a hydrophilic resin layer having a thickness of 4 μm. This flexographic printing original plate is subjected to an entire surface exposure process for 10 minutes, the resin layer 2 is cured, and subsequently using “ZED MINI (device name)” (carbon dioxide laser device, manufactured by Lusha), an output of 250 Laser engraving with Watt. The flexographic printing plate after laser engraving was washed with water to form a flexographic printing plate.

<Evaluation>
[Removability of residue]
About the flexographic printing plates obtained in Examples 1 and 2 and Comparative Examples 1 and 2, residue removability was evaluated according to the following criteria.
A: Residues were easily removed by washing.
○: The residue was removed by washing.
Δ: Some residue remains after washing.
X: The residue is hardly removed.

[Heat melting]
Furthermore, the degree of thermal melting of the edge portions of the flexographic printing plates obtained in Examples 1 and 2 and Comparative Examples 1 and 2 was evaluated.

The above evaluation results are shown in Table 1.

  As shown in Table 1, in the flexographic printing original plate on which the hydrophilic resin layer containing polyvinyl alcohol is formed, it is understood that the thermal melting is slight and the residue removability is good. On the other hand, in the flexographic printing original plate in which the hydrophilic resin layer is not formed, it can be seen that although the thermal melting is slight, the residue removing property is poor.

Claims (11)

  (A) A support layer, (B) an elastomeric binder, and a resin layer formed from an elastomeric composition containing a crosslinking agent capable of crosslinking the elastomeric binder, and (C) a hydrophilic resin layer are laminated. A flexographic printing original plate characterized by comprising:   The flexographic printing original plate according to claim 1, wherein the elastomeric composition further contains a plasticizer.   The said hydrophilic resin layer is a layer formed from the material which has as a main component the hydrophilic resin in which the difference of thermal decomposition start temperature and melting | fusing point exists in the range of 1 to 200 degreeC. The flexographic printing original plate according to 1 or 2.   The flexographic printing original plate according to claim 3, wherein the hydrophilic resin is a vinyl polymer.   The flexographic printing plate precursor according to claim 3 or 4, wherein the hydrophilic resin is polyvinyl alcohol.   The flexographic printing plate precursor according to any one of claims 3 to 5, wherein the hydrophilic resin is polyvinyl alcohol having a saponification degree of 50 mol% or more.   The flexographic printing plate precursor according to any one of claims 1 to 6, wherein the hydrophilic resin layer has a thickness of 3 µm to 10 µm.   The flexographic printing plate precursor according to any one of claims 1 to 7, wherein the elastomeric composition further contains a photoinitiator.   The flexographic printing plate precursor according to any one of claims 1 to 7, wherein the elastomeric composition further contains a thermal polymerization initiator. A step of irradiating the flexographic printing plate precursor according to claim 8 with an actinic ray to cure the resin layer;
Laser engraving the cured resin layer by laser irradiation from the hydrophilic resin layer side;
And a step of removing the residue generated by laser engraving and the hydrophilic resin layer by washing with water. Heat-treating the flexographic printing original plate according to claim 9 to cure the resin layer;
Laser engraving the cured resin layer by laser irradiation from the hydrophilic resin layer side;
And a step of removing the residue generated by laser engraving and the hydrophilic resin layer by washing with water.