JP6501150B2 - Letterpress printing original plate for laser engraving and method for producing letterpress printing plate obtained using the same - Google Patents

Description

  The present invention relates to a printing plate for laser engraving which forms an image by laser light irradiation to form a printing plate, and a method for producing a printing plate obtained by using the printing plate.

  Conventionally, a letterpress printing plate used for various packaging materials, seals, label printing, and various other types of printing conventionally exposes a printing original plate made of a photosensitive resin in accordance with an image to crosslink the resin in the exposed area and then unexposed area In recent years, in order to improve the efficiency of printing plate production, printing plates by laser engraving, in which a relief image is directly formed on a printing original plate using a laser, are becoming widespread. is there. In the process of producing a printing plate by laser engraving, irregularities are formed on the surface of the printing plate by irradiating a printing plate with a laser beam according to an image to thermally decompose the image forming material of the irradiated portion.

  As a printing base plate for laser engraving, technical application to a flexo printing plate has been advanced, and a laser printing engravable flexo printing plate precursor or a flexo printing plate obtained by laser engraving is disclosed in Patent Documents 1 and 2. In these documents, a monomer is mixed with an elastomeric rubber as a binder to produce a flexographic printing plate, and after curing by thermal crosslinking or photocrosslinking, laser engraving is performed to obtain a flexographic printing plate. However, these are flexographic printing plates suitable for water-based inks and ester inks, and are not suitable for resin letterpress applications where oil-based inks are mainly used.

  On the other hand, as a printing base plate for laser engraving used for letterpress printing, a printing plate made of a resin composition in which a photopolymerizable compound and a photopolymerization initiator are mixed with a polymer compound such as polyvinyl alcohol or modified polyvinyl alcohol or polyether polyamide is patented It is disclosed by the documents 3-5.

  However, as a printing plate for laser engraving used for letterpress printing, a printing plate capable of satisfying both the laser engraving property and the printing performance has not been obtained. The biggest problem at the time of laser engraving is that resin residues generated by laser irradiation are likely to remain attached to the plate without being removed even by suction during laser irradiation or cleaning after laser irradiation, and the laser non-printing plate The resin residue attached to the irradiated portion (convex portion) tends to receive an ink at the time of printing and cause a printing failure.

  With regard to the problem of adhesion of the resin residue, the content of the (meth) acryloyl group in the photosensitive resin composition is optimized to make the crosslinked state suitable for laser engraving, thereby reducing the laser engraving residue and reducing the laser It has been proposed to suppress resin melting at the time of engraving (see Patent Documents 6 and 7). In addition, it is also proposed that the resin residue can be easily removed by brush cleaning or the like using water as a solvent, even if a resin residue is attached during laser engraving, by containing a basic tertiary nitrogen atom. Patent Documents 6 and 7). However, since it takes time to remove the resin residue by brush cleaning or the like in the prior art, there is a problem that the halftone dot surface is scraped off and the long-term printability is lacking.

Patent No. 2846954 Unexamined-Japanese-Patent No. 11-338139 gazette JP-A-11-170718 JP, 2006-002061, A JP 2001-328365 A WO 09/081889 WO 10/074210

  The present invention has been made in view of the current state of the prior art, and its object is to wash resin by washing with a brush or the like so that resin residue at the time of laser engraving can be easily removed without scraping the halftone dot surface, and long-term printing It is an object of the present invention to provide a relief printing plate precursor for laser engraving capable of producing a printing plate having excellent properties, and a method for producing a relief printing plate obtained using the same.

  The inventors of the present invention conducted intensive studies on a resin composition suitable for a printing plate precursor for laser engraving in order to achieve the above object, and as a result, when a thermal acid generator is contained in the photosensitive resin composition, laser irradiation is performed. It has been found that the resin residue can be easily removed by washing with water due to the generation of acid, and the present invention has been completed.

That is, the present invention has the following configurations (1) to (5).
(1) A lithographic printing plate precursor for laser engraving, which is used to form a printing plate by forming an image by irradiating a laser beam after curing the photosensitive resin composition layer by ultraviolet irradiation, which is the photosensitive resin composition At least one basic tertiary nitrogen atom-containing polymer compound selected from the group consisting of polyetherureaurethane, polyetheramide, and polyamide, a photopolymerizable unsaturated compound, a photopolymerization initiator, and a thermal acid A generator, wherein at least a part of the basic tertiary nitrogen atoms in the basic tertiary nitrogen atom-containing polymer compound is quaternized by a quaternizing agent, the thermal acid generator And 0.1 to 20% by weight in the photosensitive resin composition.
(2) The relief printing original plate for laser engraving as described in (1), wherein the thermal acid generator is an onium salt.
(3) The relief printing original plate for laser engraving as described in (1), wherein the thermal acid generator is at least one onium salt selected from the group consisting of iodonium salts, sulfonium salts, and ammonium salts. .
(4) The relief printing original plate for laser engraving according to any one of (1) to (3), which is used for engraving with an infrared laser.
(5) The method is characterized by including removing by water the resin residue attached to the printing plate surface obtained by laser engraving the relief printing original plate for laser engraving according to any one of (1) to (4). A method of producing a letterpress printing plate to be used.

  Since the photosensitive resin composition of the letterpress printing original plate for laser engraving of the present invention contains a thermal acid generator, the water solubility of the basic tertiary nitrogen atom-containing polymer compound by the acid generated by the laser light irradiation The resin residue can be easily removed without scraping the halftone dot surface by water washing with brush washing or the like, and long-term printing can be tolerated.

  The relief printing original plate for laser engraving of the present invention is used to form a printing plate by forming an image by irradiating a laser beam after curing the photosensitive resin composition layer by irradiating ultraviolet light, and the photosensitive resin composition In addition to the polymer compound, the photopolymerizable unsaturated compound and the photopolymerization initiator, the product contains a thermal acid generator.

  The polymer compound contained in the photosensitive resin composition of the present invention is at least one basic tertiary nitrogen atom-containing polymer compound selected from the group consisting of polyether urea urethane, polyether amide, and polyamide. is there. The polymer compound preferably does not contain an ester bond. When an ester bond is present in the polymer compound, decomposition or exchange reaction occurs due to hydrolysis or transesterification by water or alcohol present at the time of production of the printing base plate, and the abrasion resistance tends to be significantly reduced.

  Polyether urea urethane is obtained by addition-polymerizing diamine and the terminal diisocyanate compound containing polyethyleneglycol in a solvent. As the diamine component, in order to satisfy both of the laser engraving performance and the printing performance, it is preferable to use a diamine which does not contain a tertiary nitrogen atom and a diamine which contains a tertiary nitrogen atom in combination. It is preferable that the diamine which does not contain a tertiary nitrogen atom contain 20 to 45 weight% of diamine which contains a tertiary nitrogen atom.

  Examples of diamines containing no tertiary nitrogen atom include trimethylenediamine, tetramethylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2, 2.4 or 2, 4,4-trimethylhexamethylenediamine, 1,3- or 1,4-bis (aminomethyl) cyclohexane, 1,3- or 1,4-aminocyclohexane, etc., but preferably 2-methylpentacene. Methylenediamine, 2,2,4- or 2,4,4-trimethylhexamethylenediamine, 1,3-bis (aminomethyl) cyclohexane.

  On the other hand, examples of the diamine containing a tertiary nitrogen atom include diamines having a basic tertiary nitrogen atom in the main chain or side chain. Specific examples include diamines having a piperazine ring and diamines other than these. Specific examples of the diamine having a piperazine ring include N, N'-bis (aminomethyl) piperazine, N, N'-bis (2-aminoethyl) piperazine, N, N'-bis (2-aminoethyl) ) Methyl piperazine, N- (aminomethyl) -N '-(2-aminoethyl) piperazine, N, N'-bis (3-aminopentyl) piperazine, N- (2-aminoethyl) piperazine, N- (amino) Propyl) piperazine, N- (ω-aminohexyl) piperazine, N- (3-aminocyclohexyl) piperazine, N- (2-aminoethyl) -3-methylpiperazine, N- (2-aminoethyl) -2,5 Pipettes such as -dimethylpiperazine, N- (2-aminopropyl) -3-methylpiperazine, N- (3-aminopropyl) -2,5-dimethylpiperazine Diamines having a gin ring.

  As a diamine other than a diamine having a piperazine ring, N, N-di (2-aminoethyl) amine, N, N-di (3-aminopropyl) amine, N, N-di (2-aminoethyl) methylamine N, N-di (3-aminopropyl) ethylamine, N, N-di (3-aminopropyl) isopropylamine, N, N-di (3-aminopropyl) cyclohexylamine, N, N-di (4- Amino-n-butyl) amine, N-methyl-N- (2-aminoethyl) -1,3-propanediamine, N, N'-dimethyl-N, N'-di (3-aminopropyl) ethylenediamine, N N'-Dimethyl-N, N'-di (3-aminopropyl) tetramethylenediamine, N, N'-diisobutyl-N, N'-di- (3-aminopropyl) hexamethylenediamine N, N'-dicyclohexyl-N, N'-di- (3-aminopropyl) hexamethylenediamine, N, N'-dicyclohexyl-N, N'-bis (2-carboxypropyl) hexamethylenediamine, N, N '-Di- (3-aminopropyl) -2,2,4-trimethyl-hexamethylenediamine, 1,2-bis (3-aminopropoxy) -2-methyl-2- (N, N-dimethylaminomethyl) Propane, 1,2-bis (3-aminopropoxy) -2-methyl-2- (N, N-diethylaminomethyl) propane, 1,2-bis (3-aminopropoxy) -2-ethyl-2- (N) , N-dimethylaminomethyl) propane, 1,3-bis (3-aminopropoxy) -2- (N, N-dimethylaminomethyl) propane and the like.

  Among the above diamines, N, N'-bis (aminoethyl) -piperazine, N, N'-bis (3-aminopropyl) piperazine, and diamines having a piperazine ring of N- (2-aminoethyl) piperazine are polymerizable. And is preferable because it is superior to the physical properties.

  The above-mentioned diisocyanate compound, which is another raw material used for polyether urea urethane, is obtained by reacting known aliphatic, alicyclic or aromatic diisocyanate with an equimolar or less amount of polyoxyethylene glycol, substantially It is a diisocyanate compound having an isocyanate group at both ends. The diisocyanate compound can be produced using a conventionally known method. That is, there is a method in which both are reacted in a solventless state with mixing and stirring, a method in which both are dissolved in an inert solvent and reacted, and the like. The reaction temperature, reaction time and the like should be determined in consideration of the reactivity and thermal stability of the two. In addition, the use ratio of diisocyanate is desirably 2.0 mol or more, particularly 2.05 mol or more with respect to 1.0 mol of polyoxyethylene glycol.

  As the diisocyanate used to obtain the diisocyanate compound, known aliphatic, alicyclic and aromatic diisocyanates can be used. For example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, p-xylylene diisocyanate, 1,3-cyclohexanedimethylisocyanate, p -Xylylene diisocyanate, 1,5-naphthalene diisocyanate, 2,6-diisocyanatomethyl caproate, diphenyl ether-4,4'-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate etc., but storage stability and reactivity In terms of aspect, aliphatic diisocyanates are preferred, and hexamethylene diisocyanate is particularly preferred.

  Further, the amino group / isocyanate group (equivalent ratio) of the reaction ratio of the diamine and the diisocyanate compound is 1.0 or more, preferably 1.02 or more. In this case, even if the excess terminal amino group remains unreacted, it is not particularly limited as long as the performance, physical properties and the like of the composition using it are not adversely affected. When the ratio of amino groups / isocyanate groups (equivalent ratio) is less than 1.0, undesirable reactions such as gelation easily occur, which is not preferable. Since the reactivity between an amine and an isocyanate is extremely large, the reaction between the two is also possible in an active solvent such as water, an alcohol such as methanol, or a mixture of water and an alcohol.

  The polyether amide is a polyamide having a polyether bond and an amide bond in the main chain, and uses polyethylene glycol as a polyether component. Polyether amides can be synthesized, for example, by polymerization according to the method described in JP-A-55-74537. Specifically, a structural unit consisting of polyethylene glycol having an amino group at an end and an aliphatic dicarboxylic acid and an aliphatic polyamide other than the structural unit can be synthesized by a known polymerization method. The introduction of the tertiary nitrogen atom can be achieved by copolymerizing a structural unit using a diamine or dicarboxylic acid having a tertiary nitrogen atom as a polyamide component used as a hard segment.

  Polyamides are homopolymers, copolymers and mixtures of two or more of these, which are synthesized according to known methods from diamines and dicarboxylic acids, or ω-amino acids, lactams or derivatives thereof. Examples of the polyamide include various nylons such as nylon 6, nylon 66, nylon 610, nylon 6/66/610, nylon 6/66/612, polyamide obtained from metaxylene diamine and adipic acid, and diaminodicyclohexylmethane Polymerized polyamides, basic nitrogen-containing copolymerized polyamides including structural units of N, N'-bis (3-aminopropyl) piperazine and adipic acid, polyethylene glycol copolymerized polyamides containing amino groups at both ends, carboxyl groups containing carboxyl groups at both ends Polyether-containing polyamides such as polyethylene glycol copolymerized polyamides, N-methylolated products of various polyamides, N-alkoxymethylated products, etc. may be mentioned, among which basic nitrogen-containing copolymerized polyamides and polyether-containing polyamides It is preferred.

  As a method of introducing basic nitrogen into polyamide, it is preferable to use diamine having a basic tertiary nitrogen atom in the main chain or side chain. Specific diamines include piperazine rings such as N, N'-bis (aminomethyl) piperazine, N, N'-bis (2-aminoethyl) piperazine, N, N'-bis (3-aminopropyl) piperazine and the like And diamines having N, N'-bis (3-aminopropyl) piperazine is particularly preferred.

  The polyether includes polyoxyalkylene glycols having a number average molecular weight of 200 to 4,000. Specific polyoxyalkylene glycols include polyoxyethylene glycol having a number average molecular weight of 200 to 4,000, polyoxypropylene glycol having a number average molecular weight of 200 to 4,000, and polytetramethylene having a number average molecular weight of 200 to 4,000. Glycol etc. are mentioned. As the polyether, polyethylene glycol having a molecular weight of 400 to 1,500 is preferable from the viewpoint of achieving both of the resilience and flexibility.

  The thermal acid generator used in the photosensitive resin composition of the present invention has a role of generating an acid by laser irradiation to improve the water solubility of the polymer compound, and, for example, iodonium salts and sulfonium salts. Onium salts such as ammonium salts and diazonium salts are preferably used. In particular, at least one onium salt selected from iodonium salts, sulfonium salts and ammonium salts is preferred.

  As iodonium salts, diphenyliodonium anthraquinone sulfonate, [4- (octyloxy) phenyl] phenyliodonium hexafluoroantimonate, bis (4-ter-butylphenyl) iodonium hexafluorophosphate, diphenyliodonium hexafluorophosphate, etc. It can be mentioned.

  As the sulfonium salt, 4-hydroxyphenyldimethylsulfonium tetrakis (pentafluorophenyl) borate, triphenylsulfonium hexafluoroantimonate, phenylmethyl-ortho-cyanobenzylsulfonium trifluoromethanesulfonate and the like can be mentioned.

  Examples of the ammonium salt include diethylammonium triflate, triethylammonium triflate, diisopropylammonium triflate, ethyldiisopropylammonium triflate and the like.

  When the content of the tertiary nitrogen atom and the quaternizing agent of the polymer compound is increased, the removability of the resin residue is improved to some extent, but it is not preferable because the image is easily damaged during the removal of the resin residue. By using the above-described thermal acid generator, while maintaining the strength of the photosensitive resin, it is possible to easily remove the resin residue by increasing the water solubility of only the laser beam irradiated portion of the polymer compound.

  The content of the thermal acid generator is preferably 0.1 to 20% by weight, more preferably 0.2 to 18% by weight, and most preferably 0.3 to 15% by weight with respect to the photosensitive resin composition. If the content of the thermal acid generator is less than the above range, water solubility can not be obtained, and if it exceeds the above range, good printing durability can not be obtained when used as a printing plate due to the shortage of other components.

  In the photosensitive resin composition of the present invention, at least a part of the basic tertiary nitrogen atoms in the polymer compound is quaternized by a quaternizing agent. The quaternizing agent may be a protic quaternizing agent or an aprotic quaternizing agent. Specific examples include maleic acid, itaconic acid, acrylic acid, methacrylic acid, cinnamic acid, glycolic acid, lactic acid, succinic acid, adipic acid, benzoic acid, glycidyl methacrylate, glycidyl acrylate, etc. Glycidyl acrylate is particularly preferred. The quaternizing agent can be contained at a maximum of 0.70 mol, particularly at a maximum of 0.60 mol, per 1000 g of the polymer compound.

  For example, as a method of incorporating a desired amount of a basic tertiary nitrogen atom quaternized by a photopolymerizable group-containing aprotic quaternizing agent into a polymer compound, a basic tertiary nitrogen in a hard segment may be used. The basic tertiary nitrogen atomic weight is determined by the compounding ratio of the atom-containing raw material, and the setting is made by increasing or decreasing the quaternization ratio of the photopolymerizable group quaternizing agent with respect to the basic tertiary nitrogen atomic weight introduced. It is possible. The quaternization ratio is the ratio of the number of moles of basic tertiary nitrogen atom quaternized with respect to the number of moles of basic tertiary nitrogen atoms contained in the polymer compound, and it is shown in mol% Be done. The degree of quaternization by the quaternizing agent is preferably 0 to 50%, and more preferably 20 to 50%. It is also possible to quaternize only with the thermal acid generator without using a quaternizing agent, but the resin residue removal stability is improved by using a quaternizing agent in combination, and the quaternizing agent is also used. By setting the quaternization ratio to 50% or less, it is possible to suppress damage to the image portion at the time of water washing.

  As a photopolymerizable unsaturated compound used for the photosensitive resin composition of this invention, a well-known photopolymerizable unsaturated compound can be used. The photopolymerizable unsaturated compound suitably used is a ring-opening addition reaction product of a known glycidyl ether of dihydric or trihydric alcohol with methacrylic acid and acrylic acid, and as the dihydric or trihydric alcohol And ethylene glycol adducts of ethylene glycol, diethylene glycol, triethylene glycol, phthalic acid, glycerin, bisphenol A, trimerol propane, diglycidyl ether acrylic acid adduct of bisphenol F, etc. It is also possible to use a mixture of two or more kinds. In the present invention, glycerin dimethacrylate, diethylene glycol diepoxy methacrylate, trimellol propane triepoxy acrylate, and trimellol propane triepoxy methacrylate are particularly preferable. The content of these photopolymerizable unsaturated compounds in the photosensitive resin composition is preferably 20 to 50% by weight.

  A well-known thing can be used as a photoinitiator used for the photosensitive resin composition of this invention, Specifically, For example, benzophenones, benzoins, acetophenones, benzyls, benzoin alkyl ether , Benzyl alkyl ketals, anthraquinones, thioxanthones and the like can be used. Preferable specific examples include benzophenone, benzoin, acetophenone, benzoin methyl ether, benzoin ethyl ether, benzyl dimethyl ketal, anthraquinone, 2-chloroanthraquinone, thioxanthone, 2-chlorothioxanthone and the like. It is preferable to contain 0.05-5 weight% of these photoinitiators in the photosensitive resin composition. When it is less than 0.05% by weight, the photopolymerization initiation ability is impaired, and when it is more than 5% by weight, the photohardenable in the thickness direction of the printing plate in the case of creating a relief for printing is lowered and the laser engraving performance is lowered. There is a fear.

  If necessary, known thermal polymerization inhibitors may be added. The thermal polymerization inhibitor is added in order to prevent an unexpected thermal polymerization due to heating such as preparation of a photosensitive resin letterpress composition, production or molding process, or dark reaction during storage of the composition. Examples of such compounds include hydroquinones such as hydroquinone, mono-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, hydroquinone monomethyl ether and the like, benzoquinone, 2,5-diphenyl-p-benzoquinone and the like. Benzoquinones, phenols, catechols, catechols such as p-tert-butyl catechol, aromatic amine compounds, bicullic acids, phenothiazine, α-naphthoquinones, anthraquinones, nitro compounds, sulfur compounds, etc. . The amount of the thermal polymerization inhibitor used is preferably 0.001 to 2% by weight, more preferably 0.005 to 1% by weight in the photosensitive resin composition. These compounds may be used in combination of two or more.

  The photosensitive resin composition of the present invention can be formed into a desired product by any known method such as heat pressing, casting, melt extrusion, solution casting, etc. other than melt molding in the case of obtaining a relief plate for printing. It can be molded into a desired desired shape.

The ultraviolet irradiation of the present invention is to form and solidify the photosensitive resin composition, and then to expose and crosslink and cure it with an ultraviolet exposure device. Specifically, after the photosensitive resin composition is molded and solidified into a sheet, this sheet-like molded product is exposed from the surface by an ultraviolet light exposure apparatus (light source: Philips 10R) of 8 mW / cm ² for 5 to 15 minutes. It is preferable to expose and crosslink cure.

  In the case of obtaining a letterpress printing original plate for laser engraving, a molded product (green plate) obtained by forming the photosensitive resin composition of the present invention into a sheet is laminated to a support via a known adhesive or not. Can be used. As the support, any one can be used such as steel, aluminum, glass, a plastic film such as polyethylene terephthalate, and a metal-deposited film. When the sheet-like molding (green plate) is supplied as a laminate in which the adhesive layer is laminated on a support, a protective layer is further stacked in contact with the sheet-like molding (white plate). As the protective layer, a plastic film, for example, a 125 μm thick polyethylene terephthalate film coated with a transparent non-tacky polymer dispersed or dissolved in a developer in a thickness of 1 to 3 μm is used. Even when the surface tackiness of the sheet-like molded article (genuine plate) is strong by bringing the protective layer having a thin polymer film into contact with the sheet-like molded article (genuine plate), protection performed in the next exposure operation It is easy to peel off the layer. The thickness of the formed article may be appropriately determined depending on the size, properties and the like of the printing original plate to be produced, and is not particularly limited, but is usually about 0.1 to 10 mm.

  The printing original plate thus obtained is attached to the surface of the plate mounting drum of the laser engraving apparatus, and the original plate of the irradiated portion is decomposed by the imagewise laser light irradiation (in particular, light irradiation by infrared laser) to form recessed portions. , Printing plate is manufactured. At this time, the resin residue of the polymer compound generated in the irradiated portion of the printing base plate can be easily removed at the time of water washing since the water solubility is improved by the acid of the thermal acid generator.

  EXAMPLES The present invention will be specifically described using examples, but the present invention is not limited to these examples.

Example 1
After dissolving 72 parts by mass of N, N'-bis (3-aminopropyl) piperazine and 18 parts by mass of 2-methylpentamethylenediamine in 550 parts by mass of methanol, 600 parts by mass of polyethylene glycol (average molecular weight 600) in the diamine solution Then, 410 parts by mass of a urethane oligomer having isocyanate groups at substantially both ends obtained by reacting 369 parts by mass of hexamethylene diisocyanate with each other was gradually added with stirring. Both reactions were completed in about 15 minutes under 50% polymer solids concentration conditions. This solution is placed in a Teflon (registered trademark) -coated petri dish, methanol is evaporated off, and the solution is dried under reduced pressure to contain 47% by weight of polyether segment, specific viscosity 1.71, and 0 in 1000 g of a polymer A polyetherureaurethane (polymer compound A) having 72 moles of tertiary nitrogen atoms was obtained.

  Next, 50.0 parts of the obtained polymer compound A and 2.6 parts by mass of glycidyl methacrylate are dissolved and reacted in 200.0 parts of methanol and 10 parts of water in a heating reaction vessel with stirring at 65 ° C. for 4 hours A quaternization reaction was carried out between the basic tertiary nitrogen atom contained therein and glycidyl methacrylate which is a photopolymerizable group quaternizing agent. Thereafter, 39.4 parts of trimethylolpropane triepoxy acrylate, 7 parts by mass of N-ethyltoluenesulfonic acid amide as a plasticizer, 0.1 parts by mass of hydroquinone monoethyl ether, 1.0 parts by mass of benzyl dimethyl ketal, a thermal acid generator As a mixture, 0.5 parts by mass of 4-hydroxyphenyldimethylsulfonium tetrakis (pentafluorophenyl) borate was added to obtain a photosensitive resin composition solution. The solution was cast on a Teflon (registered trademark) -coated petri dish, methanol was removed in a dark room, and then dried under reduced pressure overnight at 40 ° C. to obtain a sheet of a photosensitive resin composition having a thickness of 800 μm.

Next, the obtained photosensitive resin composition sheet is sandwiched between a film (support) in which a polyester-based adhesive layer is coated on a 250 μm-thick polyethylene terephthalate film, and a 125 μm-thick polyethylene terephthalate film (protective film). By pressing with a heat press at 100 ° C. and a pressure of 100 kg / cm ² , a sheet-like molding having a thickness of 1.05 mm was obtained.

Next, the sheet-like molded article from a distance of a height 5cm from the surface of 8 mW / cm ² UV exposure machine: exposing the front and back 10 minutes by (light source Philips 10R), after crosslinking and curing, the thickness of 125μm The polyethylene terephthalate film was peeled off to prepare a printing plate for laser engraving.

Examples 2 to 6
Printing original plates for laser engraving of Examples 2 to 6 were produced in the same manner as in Example 1 except that the addition amount and type of the thermal acid generator described in Example 1 were changed as shown in Table 1.

Example 7
Add acrylonitrile at both ends of polyoxyethylene glycol of average molecular weight 600, 139.5 parts by mass (125 parts by mass after condensation) of equimolar salt of N, N'-bis (3-aminopropyl) piperazine and adipic acid , 313.5 parts by mass (300 parts by mass after condensation) of an equimolar salt of α, ω-diaminopolyoxyethylene and adipic acid obtained by hydrogen reduction of this, and 75 parts by mass of ε-caprolactam (75 parts after condensation) Part) is melt-polymerized under ordinary conditions to obtain a polyetheramide (polymer compound B) containing a polyether in the main chain and having 0.72 mol of tertiary nitrogen atoms in 1000 g of the polymer compound The

  A photosensitive resin composition is prepared in the same manner as in Example 1 based on the composition described in Table 2 for the obtained polymer compound B, and a sheet-like molded article and a laser engraving are obtained from the obtained photosensitive resin composition. I got the original version.

Examples 8 to 12
A printing original plate for laser engraving of Examples 8 to 12 was produced in the same manner as in Example 1 except that the amount and type of the thermal acid generator described in Example 7 were changed as shown in Table 2.

Example 13
6. 52.5 parts by weight of ε-caprolactam, 40.0 parts by weight of a nylon salt of N, N'-bis (3-aminopropyl) piperazine and adipic acid, and a nylon salt of 1,3-bisaminomethylcyclohexane and adipic acid By melt polycondensation with 5 parts by weight, a copolymerized polyamide (polymer compound C) having 1.19 moles of tertiary nitrogen atoms in 1000 g of the polymer compound was obtained.

  A photosensitive resin composition is prepared in the same manner as in Example 1 based on the composition described in Table 4 for the obtained polymer compound C, and a sheet-like molded article and a laser engraving are obtained from the obtained photosensitive resin composition. I got the original version.

Examples 14 to 18
A printing original plate for laser engraving of Examples 14 to 18 was produced in the same manner as in Example 1 except that the addition amount and type of the thermal acid generator in Example 13 were changed as described in Table 3.

Comparative Example 1 and Comparative Example 2
Comparative Example 1 is the same photosensitive resin composition as Example 1 except that it does not contain the thermal acid generator at all, and Comparative Example 2 has the content of the photosensitive resin composition of the thermal acid generator of 30. The photosensitive resin composition was the same as in Example 1 except that it was 0% by mass, and a printing original plate for laser engraving was produced in the same manner as in Example 1.

Comparative Example 3 and Comparative Example 4
Comparative Example 3 is the same photosensitive resin composition as Example 7 except that it does not contain the thermal acid generator at all, and Comparative Example 4 has a content of the thermal acid generator in the photosensitive resin composition of 30. The photosensitive resin composition was the same as in Example 7 except that the content was 0% by mass, and a printing original plate for laser engraving was produced in the same manner as in Example 7.

Comparative Example 5 and Comparative Example 6
Comparative Example 5 is the same photosensitive resin composition as Example 13 except that the thermal acid generator is not contained at all, and in Comparative Example 6, the content of the thermal acid generator in the photosensitive resin composition is 30. The photosensitive resin composition was the same as in Example 13 except that the content was 0% by mass, and a printing original plate for laser engraving was produced in the same manner as in Example 13.

  Next, the printing original plate produced in the above-mentioned Example and comparative example was wound with a double-sided tape around a plate mounting drum of a laser engraving device, and laser engraving was performed under the following conditions. At the same time as the start of laser engraving, the dust collector installed near the laser gun was operated to continuously discharge the engraved resin residue out of the apparatus. After laser engraving, the plate removed from the mounting drum was brush-washed with running water to remove a small amount of resin residue adhering to the plate surface, and dried to obtain a printing original plate.

The laser engraving system is a FlexPose equipped with a 300W carbon dioxide laser from Luescher Flexo! direct was used. The specifications of this apparatus were a laser wavelength of 10.6 μm, a beam diameter of 30 μm, a plate mounting drum diameter of 300 mm, and a processing speed of 1.5 hours / 0.5 m ² . The conditions for laser engraving are as follows. (1) to (3) are conditions unique to the device. Conditions (4) to (7) can be arbitrarily set, and the standard conditions of this device were adopted for each condition.
(1) Resolution: 2540 dpi
(2) Laser pitch: 10 μm
(3) Drum rotational speed: 982 cm / sec (4) Top power: 9%
(5) Bottom power: 100%
(6) Shoulder width: 0.30 mm
(7) Evaluation image: 150 lpi, halftone dots every 1% from 0 to 100%

The following evaluation items were investigated for the obtained printing plate.
(1) Adhesion degree of resin residue on printing plate surface The adhesion state of resin residue on printing plate surface is visually inspected using a 10 × magnifying loupe, ◎: almost no adhesion, ○: some adhesion , Δ: considerable adhesion, ×: intense adhesion, indicated by 4 stages.

(2) Shaping depth of printing plate dot surface Ultra-depth color 3D shape measurement microscope (VK-9510 manufactured by KEYENCE CORPORATION) using 150 line 1% halftone surface cutting depth of printing plate with reference to solid part (μm) was measured. Specifically, the difference in height of halftone dots, which was lowered relative to the solid portion, was measured as the scraping depth.

(3) 150 lpi minimum dot reproducibility The 150 lpi minimum dot reproducibility was measured using a 10 × magnification loupe.

(4) Removability of Adhered Resin Residue The ease of removal of the resin residue adhered to the printing plate surface after laser engraving was evaluated. Specifically, the resin residue was manipulated while water was applied using a brush of 10 cm × 10 cm in which fibers made of polyethylene terephthalate having a diameter of 160 μm were implanted, and the removability was evaluated based on the following criteria.
:: can be removed by rubbing within 8 times, :: can be removed by rubbing within 8 and 15 times, △: can be removed by rubbing within 15 and 30 times, ×: 30 or more rubbing But it can not be removed, and resin adheres to the brush.

(5) Printability at high speed printing Using a seal printing rotary press as a letter press, 1000 and 2000 copies of UV ink are printed at a speed of 100 m / min, and highlight printability and A solid ink rider was judged.
[Highlight printability]
○: 3L highlight of 150 lpi can print clearly without unevenness.
Fair: slight unevenness in density at 3% highlight of 150 lpi.
X: There is uneven density at 3% highlight of 150 lpi.
[Fitted part ink riding]
○: It can print without unevenness in the ink riding of a solid part.
Fair: There is slight unevenness in density on the ink coverage of the solid part.
X: There is uneven density in the ink riding on the solid part.

The evaluation results of Examples and Comparative Examples are shown in Tables 1 to 3 below together with the composition of the photosensitive resin composition.

  As can be seen from the evaluation results in Tables 1 to 3, the printing original plate for laser engraving containing the thermal acid generator in the photosensitive resin composition in the range of 0.1 to 20% by mass is excellent in resin removability, It can be seen that the removal depth of the halftone dot surface is shallow and the long-term printability of 2000 parts is excellent. On the other hand, in the comparative example which does not contain the thermal acid generator at all, the abrasion depth of the halftone dot surface becomes high, and the long-term printability can not be satisfied. Further, in the comparative example in which the thermal acid generator is contained in excess of 20% by mass, long-term printability can not be satisfied as well.

  The resin composition of the present invention can easily remove the resin residue generated at the time of laser engraving without scraping the halftone dot surface, and can provide a printing original plate for laser engraving having excellent long-term printability.

Claims (5)

  It is a letterpress printing original plate for laser engraving used to form an image by laser light irradiation to form a printing plate after curing the photosensitive resin composition layer by ultraviolet irradiation, and the photosensitive resin composition is poly At least one basic tertiary nitrogen atom-containing polymer compound, a photopolymerizable unsaturated compound, a photopolymerization initiator, and a thermal acid generator selected from the group consisting of ether urea urethane, polyether amide, and polyamide At least a part of the basic tertiary nitrogen atoms in the basic tertiary nitrogen atom-containing polymer compound is quaternized by a quaternizing agent, and the thermal acid generator is A relief printing original plate for laser engraving characterized in that it is contained in an amount of 0.1 to 20% by weight in the photosensitive resin composition.   The relief printing original plate for laser engraving according to claim 1, wherein the thermal acid generator is an onium salt.   The relief printing original plate for laser engraving according to claim 1, wherein the thermal acid generator is at least one onium salt selected from the group consisting of an iodonium salt, a sulfonium salt, and an ammonium salt. The relief printing original plate for laser engraving according to any one of claims 1 to 3, which is used for engraving with an infrared laser.   A relief printing plate comprising removing the resin residue adhering to the plate surface of the printing plate obtained by laser engraving the relief printing original plate for laser engraving according to any one of claims 1 to 4 with water. Production method.