Metal printing ink composition and printed matter

Abstract

To provide a metal printing ink composition that achieves reduction in use of an aromatic hydrocarbon solvent and provides excellent print suitability such as on-press stability, resistance to misting, and transferability.SOLUTION: A metal printing ink composition contains a resin, a pigment, and a solvent, wherein the solvent contains a paraffinic hydrocarbon and / or a naphthenic hydrocarbon, and a higher alcohol having 6 or more carbon atoms. In the metal printing ink composition, a mass ratio between a total amount of the paraffinic hydrocarbon and the naphthenic hydrocarbon, and the higher alcohol having 6 or more carbon atoms is 50 / 50 to 95 / 5.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ink composition for metal printing. More specifically, the present invention relates to an ink composition for metal printing that uses a reduced amount of aromatic hydrocarbon solvent and has excellent printability, such as on-press stability, misting resistance, and transferability, as well as a method for coating a substrate with the ink and a printed material. [Background technology]

[0002] Metal containers are used in a wide variety of applications, including beverage containers, general-purpose cans, and candy cans. Metal containers are primarily manufactured using two methods. One method involves printing and painting a sheet metal plate, followed by cutting, welding, and other processes to create the desired can body. The other method involves punching a metal plate, ironing it, and then forming it into a cylindrical shape with a bottom, and then printing and painting the body of the can. The latter method is specifically called a seamless can.

[0003] Metal printing ink compositions are printed on the surfaces of metal containers to provide various designs, ingredient labels, etc. When printing on metal containers, printing ink is supplied from an ink fountain, transferred to the image area of ​​the printing plate via multiple rolls, and then transferred to a blanket, after which it is printed on the metal substrate. Metal printing can be performed using a lithographic offset method or a dry offset method using a resin relief plate.

[0004] In recent years, metal printing has become faster in response to the trend toward improved productivity, while the performance standards required for the designs expressed through printing have also increased. The performance requirements for metal printing inks include workability, printability, and design reproducibility.

[0005] To impart the misting resistance, on-press stability, and finish varnish suitability required of ink compositions, solvent components containing aromatic rings have traditionally been used in inks for metal printing, either alone or in combination with other solvents (Patent Document 1, Patent Document 2).

[0006] However, in recent years, concerns have arisen about the effects of organic solvents with aromatic rings on the human body and on environmental pollution. Aromatic hydrocarbons such as benzene, toluene, and xylene are subject to the PRTR system's Class 1 Designated Chemical Substances Act, and their emissions are subject to control. Aromatic hydrocarbon solvents, which are primarily used in inks for metal printing, as described in Patent Documents 1 and 2, are less harmful than benzene and are not subject to regulation. However, there is a growing demand for inks that are primarily made of non-aromatic solvents, which place less strain on the human body and the environment. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-168970 [Patent Document 2] Patent No. 7353551 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to provide an ink composition for metal printing that reduces the amount of aromatic hydrocarbon solvent used and has excellent printability, such as on-press stability, misting resistance, and transferability, as well as a method for coating a substrate using the ink, and a printed matter. [Means for solving the problem]

[0009] As a result of extensive research into the above-mentioned problems, the inventors have found that the above-mentioned problems can be solved by using the ink for metal printing described below, and have thus achieved the present invention.

[0010] That is, the present invention relates to an ink composition for metal printing containing a resin, a pigment, and a solvent, wherein the solvent contains a paraffinic hydrocarbon and / or a naphthenic hydrocarbon and a higher alcohol having 6 or more carbon atoms.

[0011] The present invention also relates to an ink composition for metal printing, characterized in that the mass ratio of the total amount of paraffinic hydrocarbons and naphthenic hydrocarbons to higher alcohols having 6 or more carbon atoms is 50 / 50 to 95 / 5.

[0012] Furthermore, the present invention relates to an ink composition for metal printing, wherein the higher alcohol is a higher alcohol having 6 to 30 carbon atoms.

[0013] Furthermore, the present invention relates to an ink composition for metal printing, wherein the higher alcohol is a higher alcohol having 10 to 20 carbon atoms.

[0014] The present invention further relates to an ink composition for metal printing, wherein the resin contains a polyester resin and / or a petroleum resin.

[0015] Furthermore, the present invention relates to an ink composition for metal printing, characterized in that the total content of paraffinic hydrocarbons, naphthenic hydrocarbons, and higher alcohols having 6 or more carbon atoms is 50 to 100 mass% relative to the total content of solvents.

[0016] The present invention further relates to a metallic print having a printed layer made of an ink composition for metallic printing on a metal medium, and an overprint layer provided on the printed layer.

[0017] Furthermore, the present invention relates to a method for producing a metallic printed item, which comprises forming a printed layer on a metal medium by dry offset printing or offset printing of an ink composition for metallic printing, and then applying an overprint varnish onto the printed layer to form an overprint layer. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide an ink composition for metal printing that reduces the amount of aromatic hydrocarbon solvent used and has excellent printability, such as on-press stability, misting resistance, and transferability. DETAILED DESCRIPTION OF THE INVENTION

[0019] The following describes in detail embodiments of the present invention. Note that the embodiments and explanations of the requirements described are examples of embodiments of the present invention, and can be implemented with appropriate modifications within the scope of the present invention.

[0020] (Ink composition for metal printing) The ink composition for metal printing of this embodiment (hereinafter also referred to as the ink composition) contains a resin, a pigment, and a solvent as essential components. Each component will be described below.

[0021] <Solvent> The ink composition of this embodiment contains a paraffinic hydrocarbon and / or naphthenic hydrocarbon, and a higher alcohol having a carbon number of 6 or more. By incorporating these solvents, the ink composition of this embodiment can reduce the amount of aromatic hydrocarbon solvent used, and has excellent on-machine stability, misting resistance, and transferability.

[0022] The paraffinic hydrocarbon is not particularly limited. Paraffinic hydrocarbons include linear normal paraffins and branched isoparaffins, such as normal heptane, normal octane, normal nonane, isoheptane, isooctane, isononane, isodecane, and trimethylpentane.

[0023] The naphthenic hydrocarbons are not particularly limited, but include cyclohexane, methylcyclohexane, cyclopentane, methylcyclopentane, and the like.

[0024] Examples of commercially available paraffinic hydrocarbons include IP Solvent 1620, IP Solvent 2028, and IP Solvent 2835 manufactured by Idemitsu Kosan Co., Ltd., D-SOL280 and D-SOL300 manufactured by Mitsubishi Shoji Chemical Co., Ltd., NS Clean 200, NS Clean 220, and NS Clean 230 manufactured by ENEOS Corporation, and NAS-5H manufactured by NOF Corporation. Examples of commercially available naphthenic hydrocarbons include Teclean N-20, Teclean N-22, Naphtesol 160, Naphtesol 200, and Naphtesol 220 manufactured by ENEOS Corporation, and EXXSOL D80, EXXSOL D110, and EXXSOL D130 manufactured by ExxonMobil Corporation. Commercially available mixed solvents of paraffinic hydrocarbons and naphthenic hydrocarbons include SPCN-80 manufactured by SPC Japan, and AF Solvent No. 5, AF Solvent No. 6, and AF Solvent No. 7 manufactured by Nippon Petrochemical Co., Ltd. These may be used alone or in combination of two or more.

[0025] The content of paraffinic hydrocarbons and naphthenic hydrocarbons in the ink composition is preferably 10 to 55 mass %, more preferably 15 to 45 mass %. When the content of paraffinic hydrocarbons and naphthenic hydrocarbons is within the above range, the ink composition exhibits good misting resistance and excellent on-machine stability.

[0026] Examples of higher alcohols having 6 or more carbon atoms include, but are not limited to, 1-decanol (C10), lauryl alcohol (C12), tridecanol (C13), isostearyl alcohol (C18), and octyldodecanol (C20). These may be used alone or in combination of two or more.

[0027] The higher alcohol having 6 or more carbon atoms preferably has 6 to 30 carbon atoms, and more preferably 10 to 20 carbon atoms. If the alcohol has fewer than 6 carbon atoms, the alcohol component may volatilize on the printing roll or penetrate into the printing roll, resulting in poor on-press stability of the ink. If the carbon number of the higher alcohol is within the above range, the ink composition exhibits good on-press stability and also has excellent misting resistance.

[0028] The content of the higher alcohol having 6 or more carbon atoms in the ink composition is preferably 3 to 20 mass %, more preferably 5 to 15 mass %. When the content of the higher alcohol having 6 or more carbon atoms is within the above range, the ink composition exhibits good on-machine stability and also has excellent misting resistance.

[0029] The blending ratio of the total amount of paraffinic hydrocarbons and naphthenic hydrocarbons to the higher alcohol having 6 or more carbon atoms is preferably 50 / 50 to 95 / 5 by mass, more preferably 60 / 40 to 90 / 10, and even more preferably 70 / 30 to 85 / 15. If the blending ratio of paraffinic hydrocarbons and naphthenic hydrocarbons is less than 50% by mass, misting resistance will be poor. If the blending ratio of higher alcohol having 6 or more carbon atoms is less than 5% by mass, on-press stability will be poor. By having the blending ratio within the above range, the ink composition will have excellent on-press stability, misting resistance, and transferability.

[0030] Of the total solvent content, the combined content of paraffinic hydrocarbons, naphthenic hydrocarbons, and higher alcohols having 6 or more carbon atoms is preferably 50 to 100 mass%, and more preferably 70 to 100 mass%. When the combined content of paraffinic hydrocarbons, naphthenic hydrocarbons, and higher alcohols having 6 or more carbon atoms is within the above range, the ink composition exhibits good misting resistance and excellent transferability.

[0031] The solvent may contain solvents other than paraffinic hydrocarbons and / or naphthenic hydrocarbons and higher alcohols having 6 or more carbon atoms, but the content of hydrophilic solvents in the total solvent content is preferably 20% by mass or less, more preferably 10% by mass or less. From the viewpoint of environmental friendliness, the content of aromatic solvents is preferably 15% by mass or less, more preferably 10% by mass or less.

[0032] The content of the solvent is not particularly limited. For example, the content of the solvent in the ink composition is preferably 10 to 60% by mass or more, and more preferably 15 to 50% by mass or more. When the content of the solvent is within the above range, the ink composition can be easily adjusted to an ink tack value that shows good printability in metal printing.

[0033] <Resin> The resin of this embodiment is not particularly limited. Examples of the resin include polyester resin, petroleum resin, epoxy resin, ketone resin, rosin-modified phenolic resin, melamine resin, and benzoguanamine resin. Among these, the resin is preferably a polyester resin and / or a petroleum resin, and among polyester resins, an alkyd resin having a structural unit derived from a fatty acid is more preferable. These resins may be used alone or in combination of two or more.

[0034] Alkyd resins exhibit good compatibility with the above-mentioned solvents, and when an overprint layer is formed on an ink layer made of an ink composition, they ensure suitability for overprint varnish, provide pigment dispersion stability, impart ink viscoelasticity suitable for printing, and have excellent ink transfer properties to metal printing media.

[0035] The alkyd resin is not particularly limited. One example is an alkyd resin having a skeleton of a condensate of a polybasic acid and a polyhydric alcohol and modified with a fatty acid. The alkyd resin of this embodiment may be a resin modified with a fatty acid or a hydrogenated fatty acid, an oil or a hydrogenated oil, a monobasic acid, or the like.

[0036] The oils and fatty acids include linseed oil, tung oil, safflower oil, soybean oil, tall oil, rice bran oil, palm oil, castor oil, dehydrated castor oil, sunflower oil, coconut oil, the fatty acids of these oils, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, isostearic acid, oleic acid, linoleic acid, linolenic acid, ricinoleic acid, eleostearic acid, 12-hydroxystearic acid, etc. The oils and fatty acids may be used in combination.

[0037] The content of fatty acid-derived structural units in the alkyd resin is preferably 35 to 65 mass % of the alkyd resin, and more preferably 40 to 60 mass % or less. A printing ink composition containing an alkyd resin with a fatty acid-derived structural unit content within the above range has excellent compatibility with the above-mentioned solvents and exhibits good on-machine stability and transferability.

[0038] Furthermore, a portion of the fatty acids may be replaced with a monobasic acid other than fatty acids. As other monobasic acids, benzoic acid, pt-butylbenzoic acid, abietic acid, 12-hydroxystearic acid, etc. may be used in combination.

[0039] Examples of polybasic acids include aromatic dibasic acids such as phthalic anhydride, isophthalic acid, and terephthalic acid, alicyclic dibasic acids such as tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and 1,4-cyclohexanedicarboxylic acid, aliphatic dibasic acids such as succinic anhydride, maleic anhydride, himic anhydride, adipic acid, sebacic acid, azelaic acid, and fumaric acid, and polybasic acids such as trimellitic anhydride and methylcyclohexene tricarboxylic anhydride. Polybasic acids may be used in combination.

[0040] The polyhydric alcohol includes dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,6-hexanediol, bisphenol A, and hydrogenated bisphenol A; trihydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, and tris(2-hydroxyethyl)isocyanurate; and tetrahydric or higher alcohols such as pentaerythritol and dipentaerythritol. Polyhydric alcohols may be used in combination.

[0041] The method for producing an alkyd resin is not particularly limited. Examples of methods for producing an alkyd resin include known methods such as the transesterification method using oil as a raw material and the fatty acid method using fatty acids as a raw material. For example, the fatty acid, polybasic acid, and polyhydric alcohol described above are charged together with xylene into a reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer, and the mixture is heated to 240°C with stirring under a nitrogen atmosphere to carry out an esterification reaction. After confirming that the desired acid value has been reached, the reaction is terminated to obtain an alkyd resin.

[0042] The polyester resin (excluding alkyd resins) is not particularly limited. For example, the polyester resin is a condensation product of a polybasic acid and a polyhydric alcohol, and is a polyester resin obtained by reacting a polybasic acid with a polyhydric alcohol using a known esterification reaction.

[0043] Polyhydric alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1,3propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,2-pentanediol, 3-methyl-1,5-pentanediol, hexanediol, octanediol, 1,4-butynediol, 1,4-butylenediol, diethylene glycol, Examples of suitable polyhydric alcohols include dihydric alcohols such as triethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, spiroglycol, and isosorbide; trihydric alcohols such as glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, and 1,2,4-butanetriol; and trihydric or higher alcohols such as sorbitol and pentaerythritol. Polyhydric alcohols may be used in combination.

[0044] Examples of polybasic acids include aromatic dibasic acids such as phthalic acid, phthalic anhydride, isophthalic acid, and terephthalic acid; alicyclic dibasic acids such as tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, and 1,4-cyclohexanedicarboxylic acid; aliphatic dibasic acids such as oxalic acid, malonic acid, succinic acid, succinic anhydride, maleic anhydride, himic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and fumaric acid; and polybasic acids such as trimellitic anhydride and methylcyclohexene tricarboxylic anhydride. Monobasic acids may also be used in combination. Examples of monobasic acids include formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oleic acid, linoleic acid, and benzoic acid.

[0045] The petroleum resin is not particularly limited, and examples thereof include aromatic petroleum resins, aliphatic petroleum resins, dicyclopentadiene petroleum resins, and petroleum resins copolymerized from these raw materials. Commercially available petroleum resins can be used. Aromatic petroleum resins include Neopolymer L-90, Neopolymer 120, Neopolymer 130, Neopolymer 140, Neopolymer 150, Neopolymer 170S, Neopolymer 160, Neopolymer E-100, Neopolymer E-130, and Neopolymer S manufactured by ENEOS Materials Corporation, and Petocol LX, Petocol 120, Petocol 130, and Petocol 140 manufactured by Tosoh Corporation. Aliphatic petroleum resins include Quinton A100, Quinton B170, Quinton M100, Quinton R100, and Quinton C200H manufactured by Nippon Zeon Co., Ltd., and T-REZ RB100 and T-REZ RB093 manufactured by ENEOS Materials. Dicyclopentadiene petroleum resins include Quinton 1105, Quinton 1325, Quinton 1340, and Quinton 1500 manufactured by Nippon Zeon Co., Ltd., and T-REZ manufactured by ENEOS Materials. HA085, T-REZ HA103, T-REZ HA105; copolymer petroleum resins such as Quinton D100, Quinton N180, Quinton P195N, Quinton S100, Quinton S195, Quinton U185, Quinton G100B, Quinton G115, Quinton D200, Quinton E200SN, and Quinton N295, all manufactured by Zeon Corporation; and Petrotack 60, Petrotack 70, Petrotack 90, Petrotack 100V, and Petrotack 90HS, all manufactured by Tosoh Corporation.

[0046] The styrene-equivalent weight-average molecular weight of the resin is preferably 500 or more and 40,000 or less. When the weight-average molecular weight of the resin is within the above range, the compatibility with the above-mentioned solvent is excellent, and the on-machine stability and transferability are good. In addition, the ink composition maintains the coating properties. In this embodiment, the weight-average molecular weight is a value measured by gel permeation chromatography (GPC).

[0047] The content of the resin in the ink composition is not particularly limited as long as it can be adjusted to a predetermined ink tack value suitable for metal printing. For example, the content of the resin in the ink composition is preferably 20 to 60% by mass or more, and more preferably 30 to 50% by mass or more. By keeping the content of the resin within the above range, the ink composition maintains its printability, such as transferability and misting resistance, and also exhibits excellent coating film properties.

[0048] <Pigments> The pigment of the present embodiment is not particularly limited, and any known inorganic or organic pigment for printing ink can be used alone or in combination.

[0049] The inorganic pigments and organic pigments preferably have heat resistance, light resistance, and retort resistance. Inorganic pigments include titanium oxide, silica, carbon black, etc. Organic pigments include phthalocyanine pigments, azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, quinophthalone pigments, etc.

[0050] The content of the pigment in the ink composition is adjusted appropriately depending on the type and purpose. For example, the content of the pigment in the ink composition is preferably 10 to 60% by mass or more, and more preferably 15 to 45% by mass or more. When the content of the pigment is within the above range, the ink composition has excellent printability such as on-press stability, good coloring power and hiding power, and excellent dispersion stability.

[0051] <Other ingredients> In addition to the above components, the ink composition of this embodiment may contain additives that are typically added to ink compositions, such as pigment dispersants, extender pigments, driers, acid catalysts, waxes, viscosity modifiers, and storage stabilizers.

[0052] ·How to adjust printing ink The method for preparing the ink composition of the present embodiment is not particularly limited. For example, the ink composition can be prepared by a conventional method using a three-roll mill, a ball mill, a bead mill, or the like.

[0053] The form of the ink composition of this embodiment varies depending on the type and content of resin, pigment, solvent, and additives. For example, the tack value is preferably 4 to 12, and more preferably 5 to 10. Here, the tack value is the value measured using a digital incometer (manufactured by Toyo Seiki Seisakusho, Ltd.) with 1.31 cc of ink, at a room temperature of 25°C, a roller temperature of 30°C, and a rotation speed of 400 rpm for 1 minute. A tack value within the above range provides excellent misting resistance and transferability.

[0054] The flow value is preferably 25 to 50, and more preferably 30 to 45. Here, the flow value indicates the value measured using a horizontal plate viscometer (spread meter) (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) at room temperature of 25°C and after 60 seconds, as the spread diameter (unit: mm). When the flow value is in the above range, good transferability is exhibited.

[0055] ·Metal printing method The printing method for the ink composition of this embodiment is not particularly limited, and can be appropriately selected from dry offset methods using resin relief plates or waterless lithographic plates, and offset methods using water-based lithographic plates. The film thickness of the ink composition is optional, but should be in the range of 0.5 to 6 μm. By ensuring that the film thickness of the ink composition is in the above range, a metal print can be obtained that is excellent in on-press stability and misting resistance, and exhibits good coloring power and hiding power.

[0056] Furthermore, examples of metal printing media on which the ink composition of the present embodiment is printed include, but are not limited to, aluminum plates, steel plates, and coated plates obtained by laminating these with polyester films, etc. These substrates may be subjected to chemical conversion treatment, plating treatment, or base coating such as size coating, white coating, or silver coating.

[0057] The method for coating a substrate according to this embodiment includes the steps of providing a printed layer on the substrate using an ink composition, applying an overprint varnish to the printed layer, and then curing the printed layer. The printed / coated article of the present invention comprises, on a substrate, a printed layer formed using a printing ink composition and an overprint layer formed using an overprint varnish. The curing step is preferably heat curing, and the heating conditions are not particularly limited. For example, the first baking step involves heating at a temperature of 180°C to 300°C for approximately 3 to 90 seconds, and the second baking step involves heating at a temperature of 180°C to 300°C for approximately 30 to 150 seconds.

[0058] The overprint varnish is preferably a thermosetting one, and any conventionally known overprint varnish for metal containers can be used without any particular limitation. Examples include polyester-melamine, polyester-epoxy-melamine, and polyester-acrylic-melamine varnishes. The overprint varnish may be either water-based or solvent-based. [Example]

[0059] The present invention will be described below based on examples and comparative examples, but the present invention is not limited to these examples. Note that the numbers in the tables below are based on mass.

[0060] Details of the raw materials used and the synthesis method are as follows.

[0061] <Solvent> AF Solvent No. 4 (paraffinic hydrocarbons and naphthenic hydrocarbons, manufactured by Nippon Petrochemicals) AF Solvent No. 6 (paraffinic hydrocarbons and naphthenic hydrocarbons, manufactured by Nippon Petrochemicals) D-sol300 (paraffinic hydrocarbon, manufactured by Mitsubishi Corporation Chemicals) EXXSOLD110 (naphthenic hydrocarbon, manufactured by ExxonMobil) Fine Oxocol 180 (C18: isostearyl alcohol, manufactured by Nissan Chemical Industries, Ltd.) Tridecanol (C13: Tridecanol, KH Neochem Co., Ltd.) NJCol 200A (C20: octyldodecanol, manufactured by New Japan Chemical Co., Ltd.) 1-Pentanol (C5:1-pentanol, manufactured by Nacalai Tesque) LAB (Linear Alkyl Benzene, Mitsui & Co., Ltd.) Sannix PP400 (propylene glycol, manufactured by Sanyo Chemical Industries, Ltd.)

[0062] <Resin> (Synthesis of alkyd resin) 45 parts of coconut oil fatty acid, 28 parts of phthalic anhydride, 37 parts of pentaerythritol, and 10 parts of xylol were charged into a four-neck flask equipped with a stirrer, and an esterification reaction was carried out at 220-230°C while circulating xylol under a nitrogen stream until the acid value reached 5.0 mgKOH / g. After the reaction was completed, the xylol was distilled off at 240°C to obtain an alkyd resin with a weight-average molecular weight of 8,000 and a number-average molecular weight of 2,500. The amount of dehydration was 10 parts. (Synthesis of polyester resin) 50 parts of tetrahydrophthalic anhydride, 35 parts of hexanediol, and 15 parts of trimethylolpropane were esterified in a conventional manner to obtain a polyester resin having an acid value of 7.0 mgKOH / g, a weight average molecular weight of 4,500, and a number average molecular weight of 2,300. (petroleum resin) Neopolymer S (ENEOS Corporation) (weight average molecular weight 1,100)

[0063] <Pigments> LIONOL BLUE FG-7351 (Phthalocyanine Blue 15:3, manufactured by Toyo Color Co., Ltd.)

[0064] <Additives> Solsperse 20000 (basic dispersant, manufactured by Lubrizol Japan Co., Ltd.)

[0065] The ink compositions of Examples 1 to 10 and Comparative Examples 1 to 6 were evaluated in the following manner, and the results are shown in Table 1.

[0066] <On-board stability> On-press stability was evaluated by evenly placing 1.31 cc of the ink composition on the rubber roll of a digital ink meter (manufactured by Toyo Seiki Seisakusho, Ltd.) and measuring the time until the tack value reached its maximum at 40°C and 1200 rpm. Note that the longer the time it takes to reach its maximum, the more suppressed the solvent release from the ink, and the less change there is in the ink's fluidity and viscosity on the ink roller or blanket, which means it can be said to have better on-press stability. (Evaluation criteria) A: It reaches its maximum value after 30 minutes. B: Maximum value between 20 and 30 minutes C: Maximum value between 10 and 20 minutes D: Maximum value in less than 10 minutes The practical evaluations are A, B and C.

[0067] <Misting resistance> 2.62 cc of the ink composition was evenly placed on the rubber roll of a digital incometer (manufactured by Toyo Seiki Seisakusho, Ltd.), and the roll was rotated at 40°C and 2400 rpm for 5 minutes. The amount of ink composition scattered onto the bottom of the roll was evaluated according to the following evaluation criteria. (Evaluation criteria) A: The amount of ink composition scattered was 20 mg or less. B: The amount of scattered ink composition was 20 to 50 mg. C: The amount of scattered ink composition was 50 to 100 mg. D: The amount of scattered ink composition was 100 mg or more.

[0068] <Transferability during high-speed printing> Using a high-speed printability tester (PM904PT manufactured by SMT Corporation), 0.2 cc of ink was supplied to a leveling roll, homogenized, and then transferred to a test rubber roll. The ink was then transferred to an aluminum plate at a printing speed of 9.5 m / s. Immediately afterwards, a thermosetting overprint varnish was applied to the printed ink layer at a speed of 2 m / s to a film thickness of 13 μm. The printed coating was then baked at 200°C for 3 minutes to produce a printed coating film. A: The ink composition is transferred evenly to the substrate, and ink adhesion is good. B: Slight unevenness in ink transfer and / or bleeding at the edges of the print C: Ink transfer is uneven and / or there is some bleeding at the edges of the print. D: Obvious uneven ink transfer and / or bleeding at the edges of the print The practical evaluations are A, B and C.

[0069] <Environmental performance> The environmental performance of the ink compositions was evaluated based on the content of aromatic solvents according to the following criteria. A: The aromatic solvent content of the total solvent content is less than 15%. B: The aromatic solvent content of the total solvent content is 15% or more.

[0070] [Table 1]

[0071] The formulations of the examples and comparative examples are as follows: Examples 1 to 10 It contains a resin, a pigment, and a solvent, and the solvent contains a paraffinic hydrocarbon and / or a naphthenic hydrocarbon, and a higher alcohol having six or more carbon atoms. (Comparative Examples 1, 2, 4, and 5) Compared to the compositions of the examples, this composition does not contain higher alcohols having 6 or more carbon atoms. (Comparative Example 3) In comparison with the compositions of the examples, it contains no paraffinic or naphthenic hydrocarbons. (Comparative Example 6) Compared to the compositions of the examples, the compositions do not contain paraffinic hydrocarbons and / or naphthenic hydrocarbons, and higher alcohols having 6 or more carbon atoms.

[0072] As shown in Table 1, when the ink composition for metallic printing described in the examples of the present invention was used, a metallic printing ink composition with excellent on-machine stability, misting resistance, and transferability during high-speed printing could be obtained compared to when the ink composition for metallic printing of the comparative example was used.

Claims

1. An ink composition for metal printing containing a resin, a pigment, and a solvent, wherein the solvent contains a paraffinic hydrocarbon and / or a naphthenic hydrocarbon, and a higher alcohol having 6 or more carbon atoms.

2. 2. The ink composition for metal printing according to claim 1, wherein the mass ratio of the total amount of paraffinic hydrocarbons and naphthenic hydrocarbons to the higher alcohol having 6 or more carbon atoms is 50 / 50 to 95 / 5.

3. 2. The ink composition for metal printing according to claim 1, wherein the higher alcohol is a higher alcohol having 6 to 30 carbon atoms.

4. 2. The ink composition for metal printing according to claim 1, wherein the higher alcohol is a higher alcohol having 10 to 20 carbon atoms.

5. 2. The ink composition for metal printing according to claim 1, wherein the resin comprises a polyester resin and / or a petroleum resin.

6. 2. The ink composition for metal printing according to claim 1, wherein the total content of the paraffinic hydrocarbons, naphthenic hydrocarbons, and higher alcohols having 6 or more carbon atoms is 50 to 100% by mass relative to the total content of the solvent.

7. A metallic printed product comprising a printed layer formed on a metal medium and comprising the ink composition for metallic printing according to any one of claims 1 to 6, and an overprint layer formed on the printed layer.

8. A method for producing a metal printed item, comprising: forming a printed layer on a metal medium by dry offset printing or offset printing the ink composition for metal printing according to any one of claims 1 to 6; and applying an overprint varnish onto the printed layer to form an overprint layer.

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