JP2019025850A - Method for producing printed matter - Google Patents

Abstract

To provide a method for producing a printed matter which exhibits good coating stability even when an aqueous overprint varnish is used, prevents volatilization and odor of a solvent in heating and curing because of being solventless, and is excellent in printabiltiy and heat curing properties.SOLUTION: A method for producing a printed matter includes a step of adhering ink onto a printing plate, a step of transferring the adhered ink onto a metal material roll, a step of coating an overprint varnish to the metal material roll, and a step of heating and drying the metal material roll after printing, where the ink contains a resin having a pigment, polyfunctional (meth)acrylate and an acidic group.

Description

  The present invention relates to a method for producing a printed matter.

  Metal containers are widely used as packaging containers for beverages, preserved foods, and the like. In particular, seamless cans obtained by forming metal raw materials into cans are used for soft drinks, carbonated drinks, alcoholic drinks, and the like.

  The surface of the seamless can is printed and painted for the purpose of enhancing the product value by design and preventing the corrosion of the metal raw material.

  In general, printing on seamless cans is curved printed on cans molded by offset printing using resin relief printing or waterless lithographic printing, and after applying a transparent overprint varnish without drying the ink, heat drying is performed. The method is taken. As an ink used in an offset printing method using a waterless lithographic plate, a lithographic printing ink containing a pigment and a varnish component is disclosed (Patent Document 1).

  In recent years, since the organic solvent contained in the overprint varnish is vaporized by heat drying and discharged into the atmosphere, the use of the aqueous overprint varnish is in progress.

  However, in the process of applying the aqueous overprint varnish on the undried ink, since a general metal printing ink contains a hydrophobic fatty acid-modified polyester and a high boiling point solvent, repelling the aqueous overprint varnish, Problems such as uneven density due to ink aggregation occur.

  Therefore, in order to impart coating stability to the aqueous overprint varnish to the ink, metal printing ink containing a highly hydrophilic diluent component (Patent Document 2), a carboxyl group at the terminal, and a hydroxyl value of 60 mgKOH Attempts have been made on metal printing ink (Patent Document 3) containing a resin that is at least / g or ink (Patent Document 4) in which the content of fatty acid in the resin is adjusted.

International Publication No. 2017/047817 (Claims) JP-A-4-106166 (Claims) JP 2009-249435 A (Claims) JP-A-11-323217 (Claims)

  However, when the diluent component having high hydrophilicity described in Patent Document 2 is used, the ink generates a large amount of mist during printing, which deteriorates the working environment. In Patent Document 3, a resin having a carboxyl group at the end and having a hydroxyl value of 60 mgKOH / g or more is used in order to prevent generation of mist and impart printability to the ink. The fatty acid content is adjusted. However, since both Patent Document 3 and Patent Document 4 contain a hydrocarbon-based organic solvent, the solvent volatilizes during heat curing, and there is a concern of air pollution and odor generation. Alternatively, an exhaust treatment device for preventing air pollution is required, and the running cost increases.

  Therefore, the present invention shows good coating stability even when an aqueous overprint varnish is used in order to overcome the problems of the prior art. Furthermore, it aims at providing the manufacturing method of the printed matter which is excellent in printability and heat-hardening property.

  Manufacture of printed matter including a step of attaching ink to a printing plate, a step of transferring the attached ink to a metal raw material, a step of applying an overprint varnish to the metal raw material, and a step of heating and drying the metal raw material after printing A method for producing a printed material, wherein the ink contains a pigment, a polyfunctional (meth) acrylate, and a resin having an acidic group.

  The present invention includes a step of attaching ink to a printing plate, a step of transferring the attached ink to a metal raw material, a step of applying an overprint varnish to the metal raw material, and a step of heating and drying the metal raw material after printing. A method for producing a printed matter, comprising: a pigment, a polyfunctional (meth) acrylate, and a resin having an acidic group, and thus exhibits good coating stability even when an aqueous overprint varnish is used. Further, the present invention relates to a method for producing a printed matter which is solvent-free and does not volatilize or smell of the solvent at the time of heat curing, and further has excellent printability and heat curability.

  Hereinafter, the present invention will be specifically described.

  The method for producing a printed material of the present invention includes a step of attaching ink to a printing plate, a step of transferring the attached ink to a metal raw material, a step of applying an overprint varnish to the metal raw material, and a metal raw material after printing. Including a step of heat drying. Usually, the above steps are performed in order.

  Examples of the printing plate used in the method for producing a printed material according to the present invention include a resin relief plate, a flexographic plate, a PS plate, and a waterless lithographic plate. However, high-definition printing is possible, and the printability on a metal raw material is excellent. It is preferable to use a waterless lithographic plate.

  Examples of the metal raw material used in the method for producing a printed material of the present invention include materials such as aluminum, steel, and a polyester laminate covering thereof, and chemical conversion treatment, plating treatment, or undercoat such as silver coat or white coat is applied. May be. In addition, it can be used for either a three-piece can in which the shape of the metal sheet during printing is a plate shape or a seamless (two-piece) can that is a can body, but a seamless can can be used from the viewpoint of productivity. preferable.

  As the step of attaching ink to the printing plate in the method for producing a printed matter of the present invention, the step of supplying well-kneaded ink to the entire surface of the printing plate by a plurality of rollers and selectively attaching the ink to the image area Can be used.

  As the step of transferring the ink to the metal raw material in the method for producing a printed matter of the present invention, either a step of transferring the attached ink directly or via a blanket can be used. In the direct transfer step, the ink exhibits good dislocation properties. In addition, the step of transferring through the blanket is such that the printing plate is less damaged and the printing durability is increased as a result of the flexible blanket being used.

  The thickness of the ink coating on the metal web is preferably 0.1 to 50 μm. When the thickness of the ink coating film is in the above range, the ink cost can be reduced while maintaining good print quality. The transferred ink may be cured by active energy rays.

  As the step of applying the overprint varnish to the metal raw material in the method for producing a printed matter of the present invention, a known method such as a varnish coater or a flexo coater can be used. The film thickness of the overprint varnish is arbitrary, but is preferably 0.1 to 50 μm.

  The heat drying conditions in the method for producing a printed material of the present invention are preferably 160 ° C. or higher, more preferably 180 ° C. or higher, more preferably 200 ° C. or higher, which is the temperature at which the polyfunctional (meth) acrylate starts thermal polymerization. is there. Further, it is preferably 260 ° C. or lower, more preferably 240 ° C. or lower, and further preferably 220 ° C. or lower, which suppresses thermal deterioration of the laminating agent or undercoat on the metal raw fabric and reduces energy by drying. The drying time is not particularly limited, but general heating for 20 seconds to 10 minutes is preferable.

  As the overprint varnish used in the method for producing a printed matter of the present invention, a conventionally known solvent-based or water-based overprint varnish can be used, but it is preferably aqueous from the viewpoint of environmental load.

  In the method for producing a printed matter of the present invention, since the pH of the overprint varnish is 8.0 or more, the affinity for the resin having an acidic group contained in the ink is high, and a good coating with respect to the aqueous overprint varnish. It is preferable because it can exhibit work stability and adhesiveness. It is preferable that the pH is 11.0 or less because damage to the printing equipment can be reduced. The pH of the overprint varnish here is a pH value measured at 25 ° C. with a 1% by mass aqueous solution of the overprint varnish.

  The overprint varnish is preferable because it contains an amine compound, so that the pH can be made basic, and it crosslinks with a resin having an acidic group in the ink by an ionic bond to improve the film strength. As the amine compound, conventionally known compounds can be used. Specifically, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, monoethanolamine, diethanolamine, N -Methyldiethanolamine, triethanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine, N-methylethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, 2-amino-2-methylpropanol, 2- (dimethylamino) -2-methylpropanol, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, melamine, poly Ruki organic amines such as alkylene oxide-modified amines, ammonia, amino resins. Specific examples of the overprint varnish containing the amine compound include polyester / melamine, polyester / epoxy / melamine, and polyester / acryl / melamine. Even those neutralized with can be used.

  The ink used in the method for producing a printed matter of the present invention has a mass reduction rate of 30% by mass or more when measured by the method of JIS K 0067: 1992 test method 4.1 method 1 method at a heating temperature of 200 ° C. It is preferable that content of a certain solvent is 1 mass% or less. The solvent volatilizes at the time of heat curing, and there is a concern of air pollution and odor generation. Alternatively, an exhaust treatment device for preventing air pollution is required and the running cost increases. Therefore, it is preferable to reduce the content thereof as much as possible.

  The ink used in the method for producing a printed material of the present invention contains a pigment. As the pigment, either or both of inorganic pigments and organic pigments generally used in ink can be used.

  Examples of inorganic pigments include titanium dioxide, calcium carbonate, barium sulfate, bengara, cadmium red, yellow lead, zinc yellow, bitumen, ultramarine, organic bentonite, alumina white, iron oxide, carbon black, graphite, aluminum, brass pieces, etc. Is mentioned. These may be subjected to a surface treatment for imparting easy dispersibility, or may be subjected to a surface treatment for a metallic tone or a pearl tone.

  Examples of organic pigments include phthalocyanine pigments, soluble azo pigments, insoluble azo pigments, lake pigments, quinacridone pigments, isoindoline pigments, selenium pigments, metal complex pigments, and specific examples thereof include phthalocyanine. Examples include blue, phthalocyanine green, azo red, monoazo red, monoazo yellow, disazo red, disazo yellow, quinacridone red, quinacridone magenta, and isoindoline yellow.

  The pigment concentration contained in the ink used in the method for producing a printed matter of the present invention is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more in order to obtain the printing paper surface density. Moreover, in order to improve the fluidity | liquidity of an ink and to acquire favorable transferability between rollers, 50 mass% or less is preferable, 40 mass% or less is more preferable, and 30 mass% or less is further more preferable.

  The ink used in the method for producing a printed material of the present invention preferably contains a polyfunctional (meth) acrylate. By containing polyfunctional (meth) acrylate, the acrylate group is crosslinked and cured by a radical reaction by heating, and exhibits excellent film properties.

  Among the polyfunctional (meth) acrylates, a polyfunctional (meth) acrylate having a hydroxyl group is preferable. The hydroxyl group improves the coating stability of the ink with respect to the aqueous overprint varnish. In addition, the cohesive force of the ink under high shear during printing is increased by the interaction such as hydrogen bonding between the polyfunctional (meth) acrylate and the resin having an acidic group, and the viscosity of the ink is increased. As a result, the occurrence of mist during the printing process is suppressed, and the stain resistance of the ink is improved. Furthermore, since the hydroxyl group stabilizes the dispersion of the pigment, the viscosity of the ink is lowered under low shear, the fluidity of the ink is improved, and good transferability is exhibited.

  When the hydroxyl value of the polyfunctional (meth) acrylate having a hydroxyl group is 70 mgKOH / g or more, the coating stability of the ink with respect to the aqueous overprint varnish, the cohesive strength of the ink, and the pigment dispersibility can be improved. Therefore, it is preferable. More preferably, it is 90 mgKOH / g or more, More preferably, it is 120 mgKOH / g or more. Moreover, since the hydroxyl value is 250 mgKOH / g or less, the transferability with respect to the metal raw material of an ink can be kept favorable, and it is preferable. More preferably, it is 200 mgKOH / g or less, More preferably, it is 180 mgKOH / g or less. In addition, a hydroxyl value can be calculated | required based on the neutralization titration method of the test method 7.1 term of JISK0070: 1992.

  The polyfunctional (meth) acrylate is difunctional as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di ( (Meth) acrylate, 1,3 butylene glycol di (meth) acrylate, 1,6 hexanediol di (meth) acrylate, 1,9 nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, etc. Among them, those having a hydroxyl group include trimethylolpropane di (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, diglycerin di (meth) acrylate. DOO, ditrimethylolpropane di (meth) acrylate, dipentaerythritol di (meth) acrylate, and their ethylene oxide adducts, propylene oxide adducts, tetraethylene oxide adduct thereof.

  Examples of trifunctional groups include trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, isocyanuric acid tri (meth) acrylate, and these ethylene oxide adducts and propylene oxide adducts. It has pentaerythritol tri (meth) acrylate, diglycerin tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, and their ethylene oxide adducts and propylene oxide adducts. And tetraethylene oxide adducts.

  The tetrafunctional group includes pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, diglycerin tetra (meth) acrylate, and these ethylene oxide adducts and propylene oxide adducts. Examples thereof include dipentaerythritol tetra (meth) acrylate and its ethylene oxide adduct, propylene oxide adduct, tetraethylene oxide adduct, and the like.

  Dipentaerythritol hexa (meth) acrylate, its ethylene oxide adduct, propylene oxide adduct, etc. are mentioned for five or more functional groups. Among them, those having a hydroxyl group include dipentaerythritol penta (meth) acrylate and its ethylene oxide adduct. , Propylene oxide adducts, tetraethylene oxide adducts and the like.

  Among them, pentaerythritol tri (meth) acrylate, diglycerin tri (meta) acrylate, which has improved ink coating stability, ink cohesiveness, pigment dispersibility, and excellent thermosetting properties for aqueous overprint varnishes. ) Acrylate and ditrimethylolpropane tri (meth) acrylate are particularly preferred.

  When the ink used in the method for producing a printed matter of the present invention contains 30% by mass or more of polyfunctional (meth) acrylate, the coating stability of the ink with respect to the aqueous overprint varnish, the cohesive strength of the ink, and the pigment dispersibility are improved. Therefore, it is preferable. More preferably, it is 35 mass% or more, More preferably, it is 40 mass% or more. Moreover, 75 mass% or less which can maintain favorable the transferability with respect to the metal original fabric of ink is preferable. More preferably, it is 70 mass% or less, More preferably, it is 65 mass% or less.

  The ink used in the method for producing a printed material of the present invention includes a resin having an acidic group.

  Examples of the acidic group of the resin having an acidic group include a carboxyl group, a sulfo group, and a phosphoric acid group, and among them, a carboxyl group having good dispersibility of the pigment is preferable.

  The acid value of the resin having an acidic group is preferably 70 mgKOH / g or more because the coating stability of the ink to the aqueous overprint varnish, the cohesive strength of the ink, and the pigment dispersibility can be improved. More preferably, it is 80 mgKOH / g or more, More preferably, it is 90 mgKOH / g or more. Further, it is preferable that the acid value is 200 mgKOH / g or less because the fluidity of the ink is maintained and the transferability is improved. More preferably, it is 170 mgKOH / g or less, More preferably, it is 150 mgKOH / g or less. In addition, the acid value of resin can be calculated | required based on the neutralization titration method of the test method 3.1 term of JISK0070: 1992. The acidic group improves the affinity for the aqueous overprint varnish and exhibits good coating stability. Furthermore, an interaction such as a hydrogen bond is formed between the acidic group contained in the resin and the aqueous overprint varnish, thereby increasing the cohesive force of the ink under high shear during printing and increasing the viscosity. As a result, the occurrence of mist during the printing process is suppressed, and the stain resistance of the ink is improved. Further, the acidic group stabilizes the dispersion of the pigment, so that the viscosity of the ink is lowered and the fluidity of the ink is improved under low shear, and thus exhibits good transferability.

  The weight average molecular weight of the resin having an acidic group is preferably 5,000 or more because the cohesive strength of the ink is improved. More preferably, it is 15,000 or more, More preferably, it is 20,000 or more. Moreover, since the fluidity | liquidity of an ink is maintained as a weight average molecular weight is 100,000 or less, it is preferable. More preferably, it is 75,000 or less, More preferably, it is 50,000 or less. In addition, the weight average molecular weight of resin can be obtained by measuring in polystyrene conversion using gel permeation chromatography (GPC).

  Examples of the resin having an acidic group include acrylic resins, styrene acrylic resins, styrene maleic resins, rosin modified maleic resins, rosin modified acrylic resins, epoxy resins, polyester resins, polyurethane resins, phenol resins, etc. Is not to be done. Among the resins listed above, acrylic resin, styrene acrylic resin, styrene maleic acid resin from the viewpoints of availability of monomers, low cost, ease of synthesis, compatibility with other ink components, dispersibility of pigments, etc. Is preferably used as a resin having an acidic group.

  Among the resins listed above, acrylic resin, styrene acrylic resin, and styrene maleic acid resin can be prepared by the following method. That is, carboxyl group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetate or their acid anhydrides, hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, dimethylaminoethyl methacrylate Amino group-containing monomers such as 2-methylmercaptoacetoxyethyl acrylate monomers, sulfo-group-containing monomers such as acrylamide t-butyl sulfonic acid, phosphoric acid such as 2-methacryloxyethyl acid phosphate It is obtained by polymerizing or copolymerizing a compound selected from a group-containing monomer, methacrylic acid ester, acrylic acid ester, styrene, acrylonitrile, vinyl acetate and the like using a radical polymerization initiator.

  Specific examples of the resin having an acidic group include (meth) acrylic acid copolymer, (meth) acrylic acid- (meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid copolymer, styrene- ( (Meth) acrylic acid- (meth) acrylic acid ester copolymer, styrene-maleic acid copolymer, styrene-maleic acid- (meth) acrylic acid copolymer, styrene-maleic acid- (meth) acrylic acid ester copolymer Examples include coalescence.

  It is preferable that the resin having an acidic group further has an ethylenically unsaturated group because the heat curability is good. The iodine value of the ethylenically unsaturated group in the resin having an acidic group is preferably 0.5 mol / kg or more and 3.0 mol / kg or less. The iodine value is preferably 0.5 mol / kg or more, and more preferably 1.0 mol / kg or more because good heat curability can be obtained. Moreover, since favorable ink storage stability is acquired, it is preferable that it is 3.0 mol / kg or less, and it is more preferable that it is 2.5 mol / kg or less.

  In addition, the iodine value of an ethylenically unsaturated group can be calculated | required by the method of the test method paragraph 6.0 of JISK0070: 1992.

  A resin having an acidic group and an ethylenically unsaturated group can be prepared by the following method. That is, by reacting a carboxyl group which is an active hydrogen-containing group in a resin having an acidic group with an ethylenically unsaturated compound having a glycidyl group or an isocyanate group, acrylic acid chloride, methacrylic acid chloride or allyl chloride. A resin having an acidic group and an ethylenically unsaturated group is obtained. However, it is not limited to these methods.

  Specific examples of the ethylenically unsaturated compound having a glycidyl group include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, glycidyl crotonic acid, glycidyl isocrotonic acid, and the like.

  Specific examples of the ethylenically unsaturated compound having an isocyanate group include acryloyl isocyanate, methacryloyl isocyanate, acryloylethyl isocyanate, and methacryloylethyl isocyanate.

  The ink used in the method for producing a printed material of the present invention preferably contains 5% by mass or more and 50% by mass or less of a resin having an acidic group. When the content of the resin is within the above range, the coating stability with respect to the aqueous overprint varnish is improved, and cohesive force and pigment dispersibility are imparted to the ink, thereby obtaining good printability.

  The ink used in the method for producing a printed matter of the present invention may contain a polymerization initiator. By including a polymerization initiator, radicals are generated by heating, and curability can be improved.

  As the polymerization initiator, those that generate active radical species are preferable. Specific examples thereof include benzophenone, methyl o-benzoylbenzoate, 4,4-bis (dimethylamino) benzophenone (also known as Michler's ketone), 4, 4-bis (diethylamino) benzophenone, 4,4′-dichlorobenzophenone, 4-benzoyl-4-methyldiphenyl ketone, 1-hydroxycyclohexyl-phenyl ketone, 4-phenylbenzophenone, hydroxybenzophenone, dibenzyl ketone, fluorenone, 2, 2-diethoxyacetophenone, 2,2-dimethoxy-2-phenyl-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- [4- (2-hydroxyethoxy)- Phenyl] -2-hi Droxy-2-methyl-1-propan-1-one, pt-butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4- Dichlorothioxanthone, benzyldimethylketanol, benzylmethoxyethyl acetal, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, anthraquinone, 2-t-butylanthraquinone, 2-amylanthraquinone, β-chloroanthraquinone, anthrone Benzanthrone, dibenzosuberone, methyleneanthrone, 4-azidobenzalacetophenone, 2,6-bis (p-azidobenzylidide) ) Cyclohexanone, 2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2-phenyl-1,2-butadion-2- (o-methoxycarbonyl) oxime, 1-phenyl-1,2-propanedione 2- (o-ethoxycarbonyl) oxime, 1,3-diphenyl-propanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propanetrione-2- (o-benzoyl) oxime, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone, naphthalenesulfonyl chloride, quinolinesulfonyl Chloride, N-phenylthioacridone, 4,4-azobisui Sobutyronitrile, diphenyl disulfide, benzthiazole disulfide, triphenylphosphine, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenyl-phosphine oxide, hydroperoxide, dialkylperoxide Examples include oxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, acetyl peroxide, acyl peroxide, cumene peroxide, 1,1-di-t-butylperoxycyclohexane, t-butylperoxybenzoate, and the like. .

  The ink used in the method for producing a printed material of the present invention can contain one or more of these polymerization initiators.

  In order to obtain good curability, the ink may contain 0.10% by mass or more of the polymerization initiator, or may contain 1.0% by mass or more. The ink preferably contains 4.0% by mass or less of a polymerization initiator because the odor of the cured film is reduced and the storage stability of the ink is improved, and more preferably 3.0% by mass or less.

  The ink used in the present invention can contain a polymerization inhibitor in order to improve stability during storage. Specific examples of the polymerization inhibitor include hydroquinone, hydroquinone monoether, N-nitrosodiphenylamine, phenothiazine, p-t-butylcatechol, N-phenylnaphthylamine, 2,6-di-t-butyl-p- Examples include methylphenol, chloranil, and pyrogallol. The addition amount of the polymerization inhibitor is preferably 0.01% by mass to 5% by mass with respect to the ink because good storage stability can be obtained.

  The ink of the present invention can contain a pigment dispersant in order to enhance the dispersibility of the pigment. Although the optimum content varies depending on the density, particle diameter, surface area, and the like of the pigment used, the pigment dispersant acts on the surface of the pigment and suppresses aggregation of the pigment. Thereby, the pigment dispersibility is enhanced and the fluidity of the ink is improved.

  The content of the pigment dispersant is preferably 5% by mass to 50% by mass with respect to the pigment because the fluidity of the ink is improved.

  Additives such as waxes, antifoaming agents, and transferability improvers can be used as necessary for the ink used in the method for producing a printed material of the present invention.

  An ink production method used in the printed matter production method of the present invention will be described. The ink, together with pigments and additives, other ingredients, kneader, three roll mill, ball mill, planetary ball mill, bead mill, roll mill, attritor, sand mill, gate mixer, paint shaker, homogenizer, revolving type stirrer, etc. It can be obtained by homogeneously mixing and dispersing with a kneader. Defoaming is preferably carried out under vacuum or reduced pressure conditions after mixing or dispersing.

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these.

<Ink creation>
The ink used in the printing test has the composition shown in Table 1 and weighed resin, polyfunctional (meth) acrylate, pigment, and various additives, and a three-roll mill “EXAKT” (registered trademark) M-80S (EXAKT). The roller gap scale of the apparatus was set to 1, the roll rotation speed scale was set to 500 rpm, and kneaded 5 times. Each ink raw material is as follows.

<Ink raw material>
Resin 1: A copolymer composed of 25% by mass of methyl methacrylate, 25% by mass of styrene and 50% by mass of methacrylic acid was prepared. Addition reaction of 0.55 equivalents of glycidyl methacrylate to the carboxyl group of the copolymer gave Resin 1 having an ethylenically unsaturated group and a hydrophilic group. The obtained resin 1 had a weight average molecular weight of 34,000, an acid value of 105 mgKOH / g, and an iodine value of 2.0 mol / kg.

  Resin 2: Resin 2 having a hydrophilic group made of a copolymer of 45% by mass of methyl methacrylate, 20% by mass of styrene and 35% by mass of methacrylic acid was obtained. The obtained resin 2 had a weight average molecular weight of 21,000 and an acid value of 220 mgKOH / g.

  Resin 3: A resin 3 having a hydrophilic group made of a copolymer of 41% by mass of methyl methacrylate, 32% by mass of styrene and 27% by mass of methacrylic acid was obtained. The obtained resin 3 had a weight average molecular weight of 28,000 and an acid value of 172 mgKOH / g.

  Resin 4: A copolymer of 31% by mass of methyl methacrylate, 35% by mass of styrene and 34% by mass of methacrylic acid was prepared. By adding 0.2 equivalent of glycidyl methacrylate to the carboxyl group of the copolymer, a resin 4 having an ethylenically unsaturated group and a hydrophilic group was obtained. The obtained resin 4 had a weight average molecular weight of 45,000, an acid value of 156 mgKOH / g, and an iodine value of 0.6 mol / kg.

  Resin 5: Resin 5 having a hydrophilic group made of a copolymer of 50% by mass of methyl methacrylate, 37% by mass of styrene and 13% by mass of methacrylic acid was obtained. The obtained resin 5 had a weight average molecular weight of 52,000 and an acid value of 87 mgKOH / g.

  Resin 6: A copolymer of 16% by mass of methyl methacrylate, 23% by mass of styrene and 61% by mass of methacrylic acid was prepared. By adding 0.7 equivalent of glycidyl methacrylate to the carboxyl group of the copolymer, a resin 6 having an ethylenically unsaturated group and a hydrophilic group was obtained. The obtained resin 6 had a weight average molecular weight of 19,000, an acid value of 72 mgKOH / g, and an iodine value of 2.9 mol / kg.

  Resin 7: A copolymer of 50% by mass of methyl methacrylate, 42% by mass of styrene and 8% by mass of methacrylic acid was prepared. By adding 0.2 equivalent of glycidyl methacrylate to the carboxyl group of the copolymer, a resin 7 having an ethylenically unsaturated group and a hydrophilic group was obtained. The obtained resin 7 had a weight average molecular weight of 22,000, an acid value of 45 mgKOH / g, and an iodine value of 0.2 mol / kg.

  Resin 8: Isopap (Daiso Chemicals, diallyl phthalate resin, no acidic group, weight average molecular weight 30,000, acid value 0 mgKOH / g).

  Multifunctional (meth) acrylate 1: A mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate “Aronix” (registered trademark) M-306 (manufactured by Toagosei Co., Ltd.). Has hydroxyl group, hydroxyl value 171 mgKOH / g.

  Multifunctional (meth) acrylate 2: A mixture of pentaerythritol diacrylate and pentaerythritol triacrylate. Has hydroxyl group and hydroxyl value of 271 mgKOH / g.

  Multifunctional (meth) acrylate 3: Glycerin dimethacrylate “NK ester” (registered trademark) 701 (manufactured by Shin-Nakamura Chemical Co., Ltd.). Has hydroxyl group, hydroxyl value 240 mgKOH / g.

  Multifunctional (meth) acrylate 4: A mixture of pentaerythritol diacrylate, pentaerythritol triacrylate and pentaerythritol tetraacrylate. Hydroxyl group, hydroxyl value 197 mgKOH / g.

  Multifunctional (meth) acrylate 5: A mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate “Miramer” (registered trademark) M340 (manufactured by MIWON). Has hydroxyl group, hydroxyl value 115 mgKOH / g.

  Multifunctional (meth) acrylate 6: A mixture of ditrimethylolpropane triacrylate and ditrimethylolpropane tetraacrylate. Has hydroxyl group, hydroxyl value 72 mgKOH / g.

  Multifunctional (meth) acrylate 7: A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate “Aronix” (registered trademark) M-402 (manufactured by Toa Gosei Co., Ltd.). Has hydroxyl group, hydroxyl value 28 mgKOH / g.

  Polyfunctional (meth) acrylate 8: Ethylene oxide-modified pentaerythritol tetraacrylate “Miramer” (registered trademark) M4004 (manufactured by MIWON), no hydroxyl group.

Polymerization inhibitor: p-methoxyphenol (manufactured by Wako Pure Chemical Industries, Ltd.)
Pigment: REGAL 250R (Cabot Specialty Chemicals, Inc.)
Extender pigment: magnesium carbonate TT (manufactured by Naikai salt industry)
Polymerization initiator: “Irgacure” (registered trademark) 907 (manufactured by BASF).

<Measurement of weight average molecular weight>
The weight average molecular weight of the resin is a value measured by gel permeation chromatography (GPC) using tetrahydrofuran as a mobile phase. The column was Shodex KF-803, and the weight average molecular weight was calculated in terms of polystyrene.

<Overprint varnish>
Overprint varnish 1: Polyester resin “Plus Coat” (registered trademark) Z-565 (manufactured by Kyoyo Chemical Co., Ltd.): 25 parts by mass, ethanolamine: 2 parts by mass, ethylene glycol monoisopropyl ether: 20 parts by mass, water: 20 A mixture of parts by weight. pH 8.8.

  Overprint varnish 2: A mixture of acrylic resin “Boncoat” (registered trademark) CE-6400 (manufactured by DIC): 20 parts by mass, ethylene glycol monobutyl ether: 25 parts by mass, and water: 15 parts by mass. pH 6.5.

  Overprint varnish 3: A mixture of acrylic resin “Boncoat” (registered trademark) VF-1040 (manufactured by DIC): 40 parts by mass, diethylene glycol monoethyl ether: 15 parts by mass, and water: 10 parts by mass. pH 10.4.

  Overprint varnish 4: Acrylic resin “Almatex” (registered trademark) K-271 (manufactured by Mitsui Chemicals): 30 parts by mass, Melamine resin “Amidia” (registered trademark) L-105 (manufactured by DIC): 10 parts by mass , Diethanolamine: a mixture of 5 parts by mass, 20 parts by mass of ethylene glycol monobutyl ether, and 10 parts by mass of water. pH 11.5.

<Printing test>
A waterless lithographic printing plate (TAC-VT4, manufactured by Toray Industries, Inc.) is mounted on a seamless can printing machine (Concorde, manufactured by DII Engineering Co., Ltd.). 50 to 100 μm) was printed at a speed of 1000 cans / minute, and after the overprint varnish was applied to the printing surface, the ink was cured by heating at 210 ° C. for 40 seconds to obtain a printed matter. The results are shown in Table 2-1 and Table 2-2.

<Measurement of pH>
The pH of the overprint varnish used in the test was measured using a pH meter (F-52, manufactured by HORIBA, Ltd.). The pH of the overprint varnish here is a pH measured at 25 ° C. by preparing a 1% by mass aqueous solution of the overprint varnish.

<Evaluation method>
The results of the printing test were evaluated as follows.
(1) Coating stability of overprint varnish The appearance of printed matter after heat curing was evaluated in the following four stages.
4: No deterioration in print quality such as ink aggregation or bleeding was observed in the printed image.
3: A slight decrease in printing quality was observed due to slight ink aggregation or ink bleeding.
2: A decrease in print quality was observed due to ink aggregation or ink bleeding.
1: A significant decrease in print quality was observed on the entire printed surface due to ink aggregation or ink bleeding.

(2) Halftone dot reproducibility When the solid density of the printed material is 1.8, the dot gain value of the 50% halftone dot portion of the printed material was measured using a reflection densitometer (manufactured by GretagMacbeth, SpectroEye). When the dot gain value is in the range of 14 ± 4%, the halftone dot reproducibility is good, and in the other range, the print quality is deteriorated due to the thickening and thinning of the halftone.

(3) Soil density When the solid density of the printed material was 2.0, the black density in the non-image area of the printed material was evaluated using a reflection densitometer (GretagMacbeth, SpectroEye). When the reflection density exceeds 0.20, the soil resistance is poor. When the reflection density is 0.10 or less, the soil resistance is good. When the reflection density is 0.05 or less, the dirt resistance is extremely high. Evaluated as good.

(4) Thermosetting The ink film hardness was measured by a pencil scratch test (JIS K 5400).

(5) Odor of printed matter After printing, the overprint varnish was not applied, and the printed matter odor when heated in an open atmosphere at 210 ° C for 40 seconds was evaluated in the following two stages.
3: There was no odor from printed matter.
2: A slight odor from the printed material was felt.
1: Odor from the printed material was felt.

[Examples 1 to 4] <Change of overprint varnish>
Using the ink 1 thus prepared, the overprint varnish was changed as shown in Table 2, and printing was performed. When the pH of the overprint varnish was in the range of 8 to 11, the coating stability of the overprint varnish was good. However, when the pH of the overprint varnish was less than 8, aggregation of the ink was observed. Partial dissolution and bleeding were observed.

[Examples 5 to 10 and Comparative Example 1] <Modification of Resin>
Printing was performed from ink 1 of Example 1 using inks 2 to 8 with different resin compositions. As the acid value of the resin increased, the coating stability improved and the background stain concentration decreased, but the halftone dot reproducibility decreased and the transferability tended to decrease. On the other hand, when the resin does not have an acid value, the coating stability is low, ink aggregation is observed, the background stain density is high, and the dot gain tends to increase. In the case of a resin having an unsaturated bond, the thermosetting property tends to be further improved.

[Examples 11 to 16] <Modification of polyfunctional (meth) acrylate>
Printing was performed from ink 1 of Example 1 using inks 9 to 14 by changing the composition of the polyfunctional (meth) acrylate having a hydroxyl group. As the hydroxyl value increased, the coating stability improved and the background stain concentration decreased, but the halftone dot reproducibility decreased and the transferability tended to decrease. The tendency for thermosetting to improve was seen, so that there were many acrylate groups of polyfunctional (meth) acrylate.

[Examples 17 to 21] <Modification of resin and polyfunctional (meth) acrylate>
Printing was performed from ink 1 of Example 1 using inks 15-19 by changing both the resin and the polyfunctional (meth) acrylate. In the case of the ink 15 using the polyfunctional (meth) acrylate having no hydroxyl group, the coating stability was lowered and the background stain density was also increased. Ink 16 in which both the acid value of the resin and the hydroxyl value of the polyfunctional (meth) acrylate are high, the background stain density is extremely low, but the dot reproducibility is reduced and the transferability is lowered. Inks 17 and 18 in which one of the acid value of the resin or the hydroxyl value of the polyfunctional (meth) acrylate is high and the other is low, the background stain density and the halftone dot reproducibility are balanced. Ink 19 in which both the acid value of the resin and the hydroxyl value of the polyfunctional (meth) acrylate were low, the coating stability was lowered and the background stain density was also increased. On the other hand, the dot reproducibility increased and the transferability improved.

[Examples 22 to 24] <Change of additive>
Printing was performed from ink 1 of Example 1 using ink 20 in which a part of the polyfunctional (meth) acrylate was replaced with a solvent, and inks 21 and 22 to which a polymerization initiator was added. Ink 20 replaced with a solvent had a high background stain density, and odor was felt in the obtained printed matter. Ink 21 added with a polymerization initiator improves the thermosetting property, but a slight odor is felt from the printed material. Ink 22 shows a clear odor from the printed material, although the thermosetting property is further improved. It was.

Claims (12)

Manufacture of printed matter including a step of attaching ink to a printing plate, a step of transferring the attached ink to a metal raw material, a step of applying an overprint varnish to the metal raw material, and a step of heating and drying the metal raw material after printing A method for producing a printed material, wherein the ink contains a pigment, a polyfunctional (meth) acrylate, and a resin having an acidic group. The method for producing a printed material according to claim 1, wherein the metal raw material is a seamless can. The method for producing a printed matter according to claim 1 or 2, wherein the printing plate is a waterless lithographic plate. The method for producing a printed material according to claim 1, wherein the overprint varnish has a pH of 8.0 or more and 11.0 or less. The manufacturing method of the printed matter in any one of Claims 1-4 in which the said overprint varnish contains an amine compound. The method for producing a printed matter according to any one of claims 1 to 5, wherein the ink has a mass reduction rate of 30% by mass or more when held in an open atmosphere at 200 ° C., and is 1% by mass or less. The method for producing a printed material according to claim 1, wherein the polyfunctional (meth) acrylate has a hydroxyl group. The method for producing a printed material according to claim 7, wherein the polyfunctional (meth) acrylate has a hydroxyl value of 70 mgKOH / g or more and 250 mgKOH / g or less. The method for producing a printed matter according to claim 1, wherein the acid value of the resin having an acidic group is 70 mgKOH / g or more and 200 mgKOH / g or less. The method for producing a printed material according to claim 1, wherein the resin having an acidic group has an ethylenically unsaturated group. The method for producing a printed matter according to claim 10, wherein the iodine value of the resin having an acidic group is 0.5 mol / kg or more and 3.0 mol / kg or less. The manufacturing method of the printed matter in any one of Claims 1-11 in which the said ink contains a polymerization initiator.