JP2007090541A - Material for laser engraving and original plate of printing plate for laser engraving - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material for laser engraving which has a high engraving speed (high engraving sensitivity). <P>SOLUTION: The material contains a compound having an acid-decomposable functional group in the main chain and/or a side chain, and an acid generating agent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser engraving material capable of forming a relief image by engraving with a laser, a printing plate precursor for laser engraving using the material, and a method for producing a relief.

  As a method for forming a relief printing plate by forming irregularities on the surface, a photosensitive composition is used, and after exposing the composition with ultraviolet light through an original film, the image portion is selectively cured. A method of removing an uncured portion with a developer, so-called “analog plate making” is well known. In many cases, analog plate making requires an original film using a silver salt material, and thus requires production time and cost of the 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 means to solve the problems associated with analog plate-making, a relief printing plate precursor is proposed in which a laser-sensitive mask layer element capable of forming an in situ image mask is provided on a layer of a photosensitive composition. (For example, see Patent Documents 1 and 2). In the plate making method using these original plates, laser irradiation is performed on the basis of image data controlled by a digital device, and an image mask is formed on the spot from the mask layer element. Thereafter, as in analog plate making, the image mask is formed. In the relief printing plate, that is, the flexographic printing plate and the resin relief printing plate, it is referred to as “digital CTP” in the plate making method in which the photosensitive composition layer and the image mask are developed and removed. Digital CTP solves the problems related to the production process of the original film described above, but there is a problem related to the treatment of the waste liquid generated in the development of the layer of the photosensitive composition. Furthermore, in the case of a flexographic plate, a chlorine-based solvent such as trichlorethylene is often used for development, which is disadvantageous in terms of work hygiene.

  As a means for solving the problems related to the development process and development waste liquid in digital CTP, a so-called “thermal development method” in which a layer of the photosensitive composition is heated to soften and remove an uncured portion has been proposed (for example, (See Patent Document 3). Since this method does not use a developing solution, it is preferable in terms of work environment, and the development waste can be incinerated without the need for special separation processing. However, the heat development method has a problem that the development speed is remarkably slower than that of the solvent development method, so that the work efficiency is low and a complicated and expensive development facility is required.

  As another means for solving the problems related to the development process and the development waste liquid, many direct engraving plate making using a laser, so-called “direct engraving CTP method” has been proposed (see, for example, Patent Documents 4 to 5). Direct engraving CTP is a method of literally engraving with a laser to form irregularities that directly become relief. Unlike analog plate making using an original image film and digital CTP that uses an image mask that also functions as an original image film, there is an advantage that the relief shape can be controlled freely. For example, it is possible to sculpt deeply a portion where the extracted character portion is reproduced on the printed matter, or sculpture with a shoulder so that the halftone dot is not collapsed by losing the printing pressure at the portion reproducing the fine halftone dot.

  The problem of direct engraving CTP is that laser engraving is slow. This is because the thickness of the mask layer element to be ablated in the digital CTP is about 1 to 10 μm, whereas in the direct engraving CTP, it is necessary to engrave at least 100 im in order to directly form a relief. It is. For this reason, a carbon dioxide laser having a high output is often used as the laser light source to be used, but it still does not reach the mask writing speed of digital CTP. Since direct engraving CTP has significantly fewer steps than digital CTP, the laser engraving speed of direct engraving CTP does not need to be equivalent to the mask drawing speed of digital CTP. Therefore, there is a demand for an object to be engraved (printing plate precursor) that is directly related to the production efficiency of the printing plate.

  The wavelength of the carbon dioxide laser used for direct engraving CTP is as large as 10.6 μm, which is 10 times the wavelength of the near-infrared laser used for digital CTP. The laser wavelength is related to the size of the laser beam diameter that can be collected. The beam diameter of the near-infrared laser is 10 to 15 μm, whereas the carbon dioxide laser has a minimum diameter of 25 μm. In order to form a fine image, a considerably advanced technique is required. Therefore, several printing plate precursors that can be engraved with a near-infrared laser have been proposed. In order to cope with the low-infrared laser with low output, the engraving speed is improved in all cases.

For example, a flexographic printing plate precursor for laser engraving including an elastomer foam has been proposed (see, for example, Patent Document 6). Although the engraving speed is improved by using a low-density foam, the strength of the printing plate is insufficient due to the low-density material, and there is a problem that the printing durability is remarkably impaired. In addition, a flexographic printing plate precursor for laser engraving containing a microsphere encapsulating a hydrocarbon-based gas has been proposed (see, for example, Patent Document 7). The engraving speed is improved by a system in which the gas in the microsphere expands due to the heat generated by the laser to collapse the material to be engraved. Since the material system contains air bubbles, there is a problem that the strength as a printing plate tends to be insufficient. In addition, gas is more easily expanded by heat than solids, and even if a microsphere with a high thermal deformation start temperature is selected, volume change due to changes in external temperature is not avoided, and stability of thickness accuracy is required. Not suitable for use in printing plates.
Japanese Patent No. 2773847 (pages 3-9) JP-A-9-171247 (pages 3-7) JP 2002-357907 (pages 7-18) Japanese Patent No. 2846954 (pages 1-7) JP-A-11-338139 (page 2-6) JP 2000-318330 A (page 2-6) US 2003/180636 (1-5 pages)

  An object of the present invention is to provide a material for laser engraving having a high engraving speed (high engraving sensitivity).

In order to solve the above problems, the present invention mainly has the following configuration. That is,
“Laser engraving material characterized by containing a compound having a functional group capable of decomposing with an acid in the main chain and / or side chain, and an acid generator”.

  According to the present invention, a laser engraving material having high engraving sensitivity to a laser can be obtained. For this reason, not only can the time required for forming the relief be shortened, but also engraving with a low-power near-infrared laser becomes possible, and a fine relief can be easily produced. Further, by using the laser engraving material of the present invention, a printing plate precursor for laser engraving having high engraving sensitivity and excellent printing durability can be obtained. The present invention can be applied not only to resin relief plates (letter press plates), flexographic plates and stamps having a convex relief, but also to intaglio plates and stencil plates, but the application range is not limited thereto.

  Embodiments of the present invention will be described below.

  The material for laser engraving in the present invention comprises a composition containing a compound having a functional group capable of decomposing with an acid in the main chain and / or side chain and an acid generator.

  The printing plate precursor for laser engraving in the present invention has a support and a layer to be engraved made of the laser engraving material.

  The combination of the compound having a functional group capable of decomposing with an acid and the acid generator can greatly improve the engraving sensitivity of the laser engraving material. The compound having a functional group capable of being decomposed by an acid here also functions as a carrier resin for a material for laser engraving, and is preferably a polymer or an oligomer. When the laser engraving material is irradiated with a high-power laser, the material is rapidly heated and physically destroyed. Conventionally, rubber plates that have been used for direct engraving are engraved only by this physical destruction, and the engraving sensitivity is low. This is because the absorption of laser is concentrated on the surface side on the laser irradiation side, so that heat necessary for physical destruction is hardly generated in the bulk portion of the rubber plate. A thermal gradient is generated between the surface and the bulk portion, and the bulk portion is heated by thermal diffusion, but the bulk portion is not engraved with a rubber plate having low engraving sensitivity. In the laser engraving material of the present invention, since the acid generated from the acid generator decomposes the carrier resin, chemical destruction is performed even in a bulk portion where heat generation is small, and engraving sensitivity is increased.

  Among compounds having a functional group that decomposes with acid in the main chain and / or side chain, resins having a functional group that decomposes with acid in the main chain have a low molecular weight due to acid generation, which improves engraving sensitivity. The effect is high, and it is most preferably used.

  When using a resin having a functional group capable of decomposing with an acid in the side chain, in order to increase the effect of improving engraving sensitivity, a resin having a low molecular weight is used, and the ends of the side chain having an acid-decomposable functional group are reacted with each other. It is preferable to form a crosslinked structure.

  Examples of the functional group capable of decomposing with an acid include an ester group, a ketal group, a thioketal group, an acetal group, and a tertiary alcohol group. Among them, an ester group is preferable.

  As the compound having an ester group, a hydroxy acid having a hydroxyl group and a carboxyl group alone or a copolycondensate, and a polycondensate of a polyfunctional alcohol and a polyfunctional carboxylic acid may be mentioned. Further, a copolycondensation product of hydroxy acid and polyfunctional alcohol and / or polyfunctional carboxylic acid is also preferably used.

  Examples of the hydroxy acid include lactic acid, glycolic acid, malic acid, glyceric acid, tartaric acid, citric acid, tartronic acid, tropic acid, salicylic acid, vanillic acid, protocatechuic acid, and gallic acid.

  Examples of the polyfunctional alcohol include ethylene glycol, propylene glycol, glycerol, pentaerythritol, pinacol and multimers thereof, polyvinyl alcohol and a vinyl acetate copolymer thereof, pyrocatechol, resorcinol, and hydroquinone.

  Examples of the polyfunctional carboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, phthalic acid, isophthalic acid, terephthalic acid, and anhydrides of these acids.

  Of the condensates obtained using these, lactic acid alone or copolycondensate, glycolic acid alone or copolycondensate, polyvinyl alcohol and its vinyl acetate copolymer and succinic acid or adipic acid condensate are preferred. Used.

  The content of the compound having a functional group capable of decomposing with an acid is preferably 10 to 90% by weight, more preferably 30 to 80% by weight, based on the total solid content of the laser engraving material. The effect of improving the engraving sensitivity is obtained by setting the content of the compound having a functional group that decomposes with an acid to 10% by weight or more, and other components are not insufficient by setting the content to 90% by weight or less. This is because good printing durability can be obtained when used as a printing plate.

  Examples of the acid generator include onium salts such as iodonium salts, sulfonium salts and diazonium salts, trihalomethyl group-substituted oxador derivatives or S-triazine derivatives, and naphthoquinone diazides. Especially, the acid generator whose temperature which generate | occur | produces an acid is 100 degreeC or more and 700 degrees C or less is preferable, and the acid generator of 150 degreeC or more and 500 degrees C or less is more preferable. By using an acid generator having an acid generation temperature of 100 ° C. or higher, it is possible to suppress the generation of acid during the manufacturing process of the material for laser engraving, and by using an acid generator having an acid generation temperature of 700 ° C. or lower, This is because the engraving speed can be improved.

  The content of the acid generator is preferably 0.1 to 30% by weight, more preferably 0.3 to 15% by weight, based on the total solid content of the laser engraving material. By making the content of the acid generator 0.1% by weight or more, an effect of improving engraving sensitivity can be obtained, and by making the content 30% by weight or less, other components are not insufficient, for example, used as a printing plate. This is because good printing durability can be obtained.

  For the purpose of improving printing durability, the laser engraving material preferably has a crosslinked structure. By introducing a crosslinked structure into the laser engraving material, it is possible to prevent wear during printing and obtain a relief having a sharp shape after laser engraving. As a means for introducing a crosslinked structure into a material for laser engraving, a method of adding a monomer that undergoes a crosslinking reaction with light or heat, and a functional group at the terminal and / or side chain of a compound having a functional group that decomposes with an acid and a crosslinking agent There is a method of reacting.

  As the monomer that crosslinks with light or heat, a known general compound such as a (meth) acrylic acid monomer, a (meth) acrylate monomer, or a combination of an epoxy compound and an amine compound can be used.

  The content of the monomer that crosslinks with light or heat is preferably 40% by weight or less, more preferably 30% by weight or less, based on the total solid content of the laser engraving material. By setting the content of the monomer that crosslinks with light or heat to 40% by weight or less, it is possible to prevent the crosslink density from becoming too dense and to suppress a decrease in engraving sensitivity.

  When using a monomer that crosslinks with light or heat, a photopolymerization initiator such as benzyldimethyl ketal or a thermal polymerization initiator such as AIBN may be added singly or in combination. The total content of the photopolymerization initiator and the thermal polymerization initiator is preferably 10% by weight or less, and more preferably 5% by weight or less, based on the total solid content of the laser engraving material. By setting the total content of the photopolymerization initiator and the thermal polymerization initiator to 10% by weight or less, the crosslinking reaction proceeds without problems, and it is possible to prevent deterioration of various performances due to lack of other components. .

  As a method of reacting a terminal group and / or a side chain functional group of a compound having a functional group capable of decomposing with an acid with a crosslinking agent, for example, when a carboxyl group is present in the compound having a functional group capable of decomposing with an acid, This can be accomplished by reacting the group with glycidyl methacrylate and then polymerizing the methacryloyl group with light or heat.

  For the purpose of improving printing durability, adjusting the hardness of relief, and imparting ink resistance, the material for laser engraving may contain a polymer other than a compound having a functional group that decomposes with an acid. For example, by using an elastomer polymer such as styrene rubber or nitrile rubber, the material for laser engraving becomes flexible, and a printing plate precursor suitable for flexographic printing can be obtained. Further, in order to obtain a resin relief printing original plate using oil-based ink, a polyamide resin resistant to oil-based ink may be used.

  The content of the polymer other than the compound having a functional group capable of decomposing with an acid is preferably 50% by weight or less, more preferably 30% by weight or less, based on the total solid content of the laser engraving material. By making the content of the polymer other than the compound having a functional group capable of decomposing with an acid 50% by weight or less, it is possible to prevent a decrease in engraving sensitivity due to lack of other components.

  In order to increase the absorption efficiency with respect to the laser used for engraving, the laser engraving material may contain a laser absorber. Since the wavelength region of the carbon dioxide laser is in the vicinity of 11 μm and the resin generally has absorption in this wavelength region, it is not always necessary to add a laser absorber. In contrast, near-infrared lasers such as semiconductor lasers, YAG lasers, and fiber lasers have an oscillation wavelength of 860 to 1150 mm, and since there are few resins that absorb in this wavelength region, lasers that are compatible with near-infrared lasers. In order to obtain a material for engraving, it is preferable to add a laser absorber.

  Examples of such laser absorbers include phthalocyanine compounds, cyanine compounds, squarylium dyes, polymethine dyes, nigrosine dyes, carbon black, chromium oxide, iron oxide, iron, aluminum, copper, and metal powders such as zinc.

  In addition, the material for laser engraving may contain additives such as a plasticizer, a heat stabilizer, a light absorber, and a dye as necessary.

  The printing plate precursor for laser engraving of the present invention has a support and a layer to be engraved composed of the material for laser engraving of the present invention. The layer to be engraved can be obtained by forming the above-mentioned laser engraving material into a sheet shape or a sleeve shape. The thickness of the layer to be engraved may be appropriately set depending on the desired size and properties of the printing plate precursor for laser engraving, and is not particularly limited, but is preferably 0.3 mm to 10 mm, more preferably 0.5 mm to 5 mm.

  The material used for the support in the present invention is not particularly limited, but those that are dimensionally stable are preferably used. For example, metals such as steel, stainless steel, and aluminum, polyesters (for example, PET, PBT, PAN), and polyvinyl chloride. Examples thereof include plastic resins, synthetic rubbers such as styrene-butadiene rubber, and plastic resins reinforced with glass fibers (such as epoxy resins and phenol resins). As the support for the printing plate precursor for laser engraving, a PET (polyethylene terephthalate) film or a steel substrate is preferably used. What is necessary is just to select the form of a support body according to whether a to-be-engraved layer is a sheet form or a sleeve form. Although the thickness of a support body does not have limitation in particular, 0.05 mm-0.5 mm are preferable from the surface of handling.

  An adhesive layer may be provided between the layer to be engraved and the support for the purpose of enhancing the adhesive force between the two layers. The layer to be engraved is relief-formed by laser engraving, and the relief surface functions as an ink deposition part. A protective film may be provided on the surface of the engraved layer for the purpose of preventing scratches and dents on the relief surface. The thickness of the protective film is preferably 25 μm or more from the viewpoint of preventing scratches and dents, and preferably 500 μm or less from the viewpoint of handleability. 50-200 micrometers is more preferable.

  A slip coat layer may be provided between the engraved layer and the protective film for the purpose of controlling the peelability of the protective film.

  The relief can be produced by controlling the laser head based on the digital data and irradiating the laser imagewise on the laser engraving material or laser engraving printing plate precursor obtained as described above. When the laser is irradiated, molecules in the material are vibrated rapidly, and the material can be engraved by the heat generated by the molecular vibration. Since the material for laser engraving or the printing plate precursor for laser engraving of the present invention has high engraving sensitivity, not only a high output carbon dioxide gas laser but also a relatively low output near red such as a YAG laser, a fiber laser, or a semiconductor laser. Engraving is also possible with an external laser. If productivity is important, a carbon dioxide laser is preferably used, and a fiber laser or a semiconductor laser is preferably used from the viewpoint of forming a fine relief.

  When engraving residue adheres to the engraving surface, a step of rinsing the engraving surface with water or a liquid containing water as a main component and washing away the engraving residue may be provided. As a means for rinsing, a method of spraying high-pressure water, a method of brushing the engraved surface mainly in the presence of water with a known batch-type or transport-type brush-type washing machine as a photosensitive resin letterpress developing machine, etc. In the case where the engraving residue cannot be removed, rinse water to which soap or a surfactant is added may be used.

  When the process of rinsing the engraving surface is performed, it is preferable to dry the relief in order to volatilize the rinse liquid from the relief obtained by engraving.

  The relief obtained in the present invention can be used for relief printing plates such as flexographic printing plates and letterpress printing plates, stamps, intaglio printing plates, stencil printing plates and the like.

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

<Preparation of a support coated with an adhesive layer>
70 parts by weight of “Byron” 31SS (toluene solution of unsaturated polyester resin, manufactured by Toyobo Co., Ltd.) and 2 parts by weight of “PS-8A” (benzoin ethyl ether, manufactured by Wako Pure Chemical Industries, Ltd.) The mixture was heated at 0 ° C. for 2 hours and then cooled to 30 ° C., and 7 parts by weight of ethylene glycol diglycidyl ether dimethacrylate was added and mixed for 2 hours. Further, 25 parts by weight of “Coronate” 3015E (ethyl acetate solution of polyvalent isocyanate resin, manufactured by Nippon Polyurethane Industry Co., Ltd.) and 14 parts by weight of “EC-1368” (industrial adhesive, manufactured by Sumitomo 3M Co., Ltd.) This was added to obtain a coating solution composition for the first adhesive layer.

  50 parts by weight of “Gohsenol” KH-17 (polyvinyl alcohol having a saponification degree of 78.5% to 81.5%, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) is mixed with “Solmix” H-11 (alcohol mixture, Nippon Alcohol Co., Ltd.). )) 200 parts by weight and 200 parts by weight of water After dissolving for 2 hours at 70 ° C., 1.5 parts by weight of “Blemmer” G (glycidyl methacrylate, manufactured by NOF Corporation) was added to After mixing for a while, 3 parts by weight of (dimethylaminoethyl methacrylate) / (2-hydroxyethyl methacrylate) / (methacrylic acid) copolymer (copolymerization ratio: 67/32/1), “Irgacure” 651 (benzyldimethyl ketal) Ciba Geigy Co., Ltd.) 5 parts by weight, “epoxy ester” 70PA (propylene glycol diglycidyl ether acrylic) 21 parts by weight of a phosphoric acid adduct (manufactured by Kyoeisha Chemical Co., Ltd.) and 20 parts by weight of ethylene glycol diglycidyl ether dimethacrylate were added and mixed for 90 minutes. After cooling to 50 ° C., “Florard” TM FC-430 (Sumitomo 3M) 0.1 part by weight was added and mixed for 30 minutes to obtain a coating solution composition for the second adhesive layer.

  The coating liquid composition for the first adhesive layer was applied on a “Lumirror” T60 (polyester film, manufactured by Toray Industries, Inc.) having a thickness of 250 μm used as a support with a bar coater so that the film thickness after drying was 40 μm. Then, after removing the solvent by placing it in an oven at 180 ° C. for 3 minutes, a coating solution composition for the second adhesive layer was applied onto the first adhesive layer with a bar coater so as to have a dry film thickness of 30 μm. Were dried in an oven for 3 minutes to obtain a laminate of second adhesive layer / first adhesive layer / support.

<Preparation of protective film coated with slip coat layer>
“GOHSENOL” AL-06 (polyvinyl alcohol having a saponification degree of 91% to 94%, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 4 parts by weight 55 parts by weight of water, 14 parts by weight of methanol, 10 parts by weight of n-propanol and n- Butanol was dissolved in 10 parts by weight of a mixed solvent to obtain a coating liquid composition for a slip coat layer.

  On the polyester film “Lumirror” S10 (manufactured by Toray Industries, Inc.) having a thickness of 100 μm, the above coating composition for the slip coat layer was applied using a bar coater so that the dry film thickness was 1.0 μm. And dried at 100 ° C. for 25 seconds to obtain a laminate of a slip coat layer / protective film.

<Synthesis of modified polyvinyl alcohol>
In a flask equipped with a condenser, partially saponified polyvinyl alcohol “GOHSENOL” KL-05 (degree of saponification 78.5% -82.0%, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 50 parts by weight, succinic anhydride 4 After adding 10 parts by weight of acetone and 10 parts by weight of acetone and heating at 60 ° C. for 6 hours, the cooling tube was removed to volatilize the acetone, followed by a purification step of eluting unreacted succinic anhydride with 100 parts by weight of acetone. After performing twice, it dried under reduced pressure at 60 degreeC for 5 hours, and obtained the modified polyvinyl alcohol which the succinic acid ester-bonded to the hydroxyl group.

<Example 1>
In a three-necked flask equipped with a stirring spatula and a condenser tube, 50 parts by weight of the modified polyvinyl alcohol, 20 parts by weight of diethylene glycol as a plasticizer, 35 parts by weight of water and 12 parts by weight of ethanol as a solvent are stirred. The modified polyvinyl alcohol was dissolved by heating at 70 ° C. for 120 minutes. Subsequently, 6 parts by weight of “Blemmer” G (glycidyl methacrylate, manufactured by NOF Corporation) was added and stirred at 70 ° C. for 30 minutes. At this stage, the reaction between the epoxy group of glycidyl methacrylate and the carboxyl group of the modified polyvinyl alcohol was almost completed, and a polymer in which a methacryloyl group was added to the end of the polymer side chain via an ester group of succinic acid was obtained. In this polymer, the methacryloyl group in the side chain is photopolymerized later to become a compound having a functional group that decomposes with an acid in the side chain.

  Furthermore, 20 parts by weight of ethylenically unsaturated monomer “light acrylate” 14EG-A (diacrylate of polyethylene glycol 600, manufactured by Kyoeisha Chemical Co., Ltd.) and “Irgacure” 651 (benzyldimethyl) as a photopolymerization initiator were added to this polymer solution. Ketal, manufactured by Ciba Geigy Co., Ltd.), 1.5 parts by weight of diphenyliodonium anthraquinone sulfonate as a thermal acid generator, and “Nopco” DF122-NS (San Nopco) as an antifoaming agent 0.05 part by weight and “Q-1300” (ammonium N-nitrosophenylhydroxylamine, manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization inhibitor were added and stirred for 30 minutes. Thus, a fluid composition solution for the engraved layer 1 was obtained.

After the support coated with the above adhesive layer is exposed from the adhesive layer side by 1000 mJ / cm ² with an ultra-high pressure mercury lamp, the composition solution for the engraved layer 1 is applied to the adhesive layer side of the support coated with the adhesive layer. It is a laminate of an uncrosslinked engraved layer 1 / second adhesive layer / first adhesive layer / support having a thickness of about 1100 μm including the substrate, cast and dried in an oven at 60 ° C. for 2 hours. A resin sheet 1 was obtained. The thickness of the resin sheet 1 was adjusted by installing a spacer having a predetermined thickness on the second adhesive layer, and scraping the composition solution for the engraved layer 1 in a portion protruding from the spacer with a horizontal metal scale. .

  The composition solution for the engraved layer 1 is developed between the resin sheet 1 and the protective film coated with the slip coat layer, laminated with a calender roll heated to 80 ° C., and the protective film / A laminated body in the order of slip coat layer / uncrosslinked engraved layer 1 / second adhesive layer / first adhesive layer / support was obtained. The clearance of the calender roll was adjusted so that the thickness of the laminate after the protective film was peeled from the laminate was 1140 μm. The unfolded coating liquid composition is allowed to stand for 1 day after lamination, whereby the remaining solvent is diffused or naturally dried to form an additional uncrosslinked layer 1 to be engraved.

The laminated body thus obtained is exposed to 2000 mJ / cm ² with an ultrahigh pressure mercury lamp from the protective film side, thereby cross-linking the uncrosslinked layer 1 to be engraved and laminating the protective film. 1 was obtained.

  For measuring the engraving sensitivity of the printing plate precursor for laser engraving, “Commax Direct” A3-40W (manufactured by Comax Co., Ltd.) equipped with a carbon dioxide laser with a maximum output of 40 W was used as a carbon dioxide laser engraving machine. After removing the protective film from the printing plate precursor 1 for laser engraving, a carbon dioxide laser engraving machine is used to rasterize a 5 cm square solid part under the conditions of laser output: 32.5 W, head speed: 600 mm / min, pitch setting: 1000 DPI Engraved. It was 0.7 mm when the engraved depth of the solid engraving portion was measured.

  Evaluation of printing durability of a printing plate obtained from a printing plate precursor for laser engraving was performed according to the following procedure. First, after removing the protective film from the printing plate precursor, a relief having a convex line having a width of 100 μm and a length of 10 cm was engraved using a carbon dioxide laser engraving machine “Commax Direct” A3-40W (manufactured by Comax Co., Ltd.). The engraving conditions were set to laser output: 32.5 W, head speed: 600 mm / min, and pitch setting: 1000 DPI. The depth of the engraved part was 0.7 mm. Thereafter, the engraving residue adhering to the relief surface was washed away with water and dried for 10 minutes to obtain a printing plate. Using the flexographic printing machine “MA-830” (manufactured by Mark Andy), the printing plate obtained in this way is UV ink “BestCure indigo UV flexo SP” (indigo ink, manufactured by T & K TOKA). The flexographic printing was done. A cushion tape having a thickness of 0.38 mm was used for attaching the relief printing plate to the plate cylinder. A sheet-like coated paper for a seal label was used as the printing material. Even after printing 200,000 m, it was confirmed that the printing was carried out without missing the convex relief formed by laser engraving, and that it had sufficient printing durability.

<Comparative Example 1>
In Example 1, a printing plate precursor 2 for laser engraving provided with an engraved layer 2 was obtained in the same manner as in Example 1 except that diphenyliodonium anthraquinone sulfonate, which is a thermal acid generator, was not added. .

  After peeling the protective film from the printing plate precursor 2 for laser engraving, a solid portion of 5 cm square was raster engraved with a carbon dioxide laser engraving machine under the conditions described in Example 1. It was 0.4 mm when the engraved depth of the solid engraving portion was measured. In Example 1, since the engraving depth was 0.7 mm in the engraved layer 1 containing 0.7 part by weight of the thermal acid generator, the engraving sensitivity is greatly improved by the presence of the thermal acid generator. I understand that.

<Example 2>
In Example 1, except that 1.0 part by weight of “KAYASORB” IRG-003 (manufactured by Nippon Kayaku Co., Ltd.) was added to the engraved layer as a near infrared laser absorber, A printing plate precursor 3 for laser engraving provided with the engraving layer 3 was obtained. The near infrared laser absorber was added after mixing with the ethylenically unsaturated monomer “light acrylate” 14EG-A.

  For measuring the engraving sensitivity of a printing plate precursor for laser engraving that supports near-infrared lasers, an 8-beam type equipped with a fiber laser with a maximum output of 11.5 W as a near-infrared laser engraving machine (the output per beam is 1.44W) “CDI SPARK” (manufactured by Esco Graphic Co., Ltd.) was used. After peeling off the protective film from the printing plate precursor 3 for laser engraving, a solid portion of 5 cm square was raster engraved with a near-infrared laser engraving machine under the conditions of laser output: 11.5 W and drum rotation speed: 600 rpm. It was 0.1 mm when the engraved depth of the solid engraving portion was measured.

<Comparative example 2>
In Example 2, a printing plate precursor 4 for laser engraving provided with an engraved layer 4 was obtained in the same manner as in Example 2 except that diphenyliodonium anthraquinone sulfonate, which is a thermal acid generator, was not added. .

  After peeling the protective film from the printing plate precursor 4 for laser engraving, a solid portion of 5 cm square was raster engraved with a near-infrared laser engraving machine under the conditions described in Example 2. When the depth of the sculpture of the solid sculpture was measured, it was not possible to engrave at all.

Claims (3)

A material for laser engraving, comprising a compound having a functional group capable of decomposing with an acid in the main chain and / or side chain, and an acid generator. A printing plate precursor for laser engraving, comprising a support and a layer to be engraved comprising the laser engraving material according to claim 1. A method for producing a relief, comprising engraving the laser engraving material according to claim 1 or the printing plate precursor for laser engraving according to claim 2 with a carbon dioxide laser or a near infrared laser.