Ink composition for metal printing and printed matter

Abstract

To provide an ink composition for metal printing which reduces the amount of aromatic hydrocarbon solvent used and has excellent printability such as on-press stability, misting resistance, and transferability. [Solution] An ink composition for metal printing containing a resin, a pigment, and a solvent, wherein the solvent contains paraffinic hydrocarbons and / or naphthenic hydrocarbons, and a higher alcohol having 6 or more carbon atoms. In the ink composition for metal printing, 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.

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 reduces the amount of aromatic hydrocarbon solvents used and has excellent printing suitability such as in-machine stability, anti-misting property, and transferability, a method for coating a substrate using the ink, and a printed matter.

Background Art

[0002] Metal containers are widely used in a variety of applications, including beverage containers, general cans, and snack cans. Metal containers are mainly manufactured by two methods. One is a method in which a sheet-like metal plate is printed and coated, and then the desired can body is made through processes such as cutting and welding. The other is a method in which a metal plate is punched, processed into a bottomed cylindrical shape through processes such as ironing, and printed and coated on its body. The latter is particularly called a seamless can.

[0003] On the surface of a metal container, an ink composition for metal printing is printed, and various designs, ingredient labels, etc. are provided. Printing on a metal container is performed by supplying printing ink from an ink pot, transferring it to the ruled part of the printing plate through a plurality of rolls, further transferring it to a blanket, and then printing it on a metal substrate. For metal printing, a lithographic offset method or a dry offset method using a resin relief plate is adopted.

[0004] In recent years, while metal printing is accelerating in speed in response to the movement for productivity improvement, the required performance level for the designs expressed by printing is also increasing. The required performance for inks for metal printing includes workability, printing suitability, design reproducibility, etc.

[0005] In order to impart anti-misting property, in-machine stability, and finish varnish suitability required for an ink composition, conventionally, solvent components having an aromatic ring have been used alone or in combination with other solvents in inks for metal printing. (Patent Document 1, Patent Document 2)

[0006] However, in recent years, there have been concerns about the impact on the human body and environmental pollution of organic solvents having an aromatic ring. Aromatic hydrocarbons such as benzene, toluene, and xylene are subject to the first-class designated chemical substances under the PRTR system, and their emissions are regulated. Although aromatic hydrocarbon solvents mainly used in metal printing inks as described in Patent Document 1 and Patent Document 2 are less harmful than benzene etc. and are not subject to regulations, there is an increasing demand for inks mainly composed of non-aromatic solvents with less burden on the human body and the environment.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention aims to provide a metal printing ink composition with reduced usage amount of aromatic hydrocarbon solvents and excellent printing suitability such as in-flight stability, anti-misting property, and transferability, a coating method for a substrate using the ink, and a printed matter.

Means for Solving the Problems

[0009] As a result of intensive studies on the above problems, the present inventor has found that the above problems can be solved by using the metal printing ink described below, and has thus completed the present invention.

[0010] That is, the present invention relates to a metal printing ink composition containing a resin, a pigment, and a solvent, wherein the solvent includes 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 the higher alcohol 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, characterized in that 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, characterized in that the higher alcohol is a higher alcohol having 10 to 20 carbon atoms.

[0014] Furthermore, the present invention relates to an ink composition for metal printing, characterized in that 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% by mass with respect to the total content of the solvents.

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

[0017] Furthermore, the present invention relates to a method for manufacturing a metal printed matter, in which the ink composition for metal printing is dry offset printed or offset printed on a metal medium to form a printing layer, and an overprint varnish is applied on the printing layer to form an overprint layer.

Effects of the Invention

[0018] According to the present invention described above, it has become possible to reduce the amount of aromatic hydrocarbon solvents used and provide an ink composition for metal printing that is excellent in printing suitability such as in-air stability, anti-misting property, and transferability.

Modes for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described in detail. Note that the description of the described embodiments or requirements is an example of the 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 the present embodiment (hereinafter also referred to as the ink composition) contains a resin, a pigment, and a solvent as essential components. Hereinafter, each component will be described.

[0021] (Solvent) The ink composition of the present embodiment contains a paraffinic hydrocarbon and / or a naphthenic hydrocarbon, and a higher alcohol having 6 or more carbon atoms. By blending these solvents in the ink composition of the present embodiment, the amount of the aromatic hydrocarbon-based solvent used can be reduced, and it is excellent in in-flight stability, anti-misting property, and transferability.

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

[0023] The naphthenic hydrocarbon is not particularly limited, and examples thereof include cyclohexane, methylcyclohexane, cyclopentane, methylcyclopentane, and the like.

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

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

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

[0027] Higher alcohols having 6 or more carbon atoms preferably have 6 to 30 carbon atoms, and more preferably 10 to 20 carbon atoms. When the number of carbon atoms of the alcohol is less than 6, the in-flight stability of the ink is poor due to the volatilization of the alcohol component on the printing roll or the penetration of the alcohol component into the printing roll. When the number of carbon atoms of the higher alcohol is within the above range, the ink composition exhibits good in-flight stability and excellent anti-misting properties.

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

[0029] The mixing 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 ratio, more preferably 60 / 40 to 90 / 10, and even more preferably 70 / 30 to 85 / 15. When the mixing ratio of paraffinic hydrocarbons and naphthenic hydrocarbons is less than 50% by mass, the anti-misting property is poor. When the mixing ratio of the higher alcohol having 6 or more carbon atoms is less than 5% by mass, the in-flight stability is poor. When the mixing ratio is within the above range, the ink composition is excellent in in-flight stability, anti-misting property, and transferability.

[0030] In the total content of the solvent, the proportion of the total content of paraffinic hydrocarbons, naphthenic hydrocarbons, and higher alcohols having 6 or more carbon atoms is preferably 50 to 100% by mass, more preferably 70 to 100% by mass. When the proportion of the total 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 anti-misting property and is also excellent in 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 the hydrophilic solvent in the total content of the solvent is preferably 20% by mass or less, more preferably 10% by mass or less. Also, from the perspective of environmental performance, 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 is preferably 10 to 60% by mass or more, more preferably 15 to 50% by mass or more in the ink composition. When the content of the solvent is within the above range, the ink composition is easily adjusted to an ink tack value showing good printing suitability in metal printing.

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

[0034] The alkyd resin shows good compatibility with the above-mentioned solvent, and when an overprint layer is provided on the ink layer composed of the ink composition, it ensures overprint gloss suitability, has excellent dispersion stability of pigments, imparts ink viscoelasticity suitable for printing, and excellent ink transferability to a metal printing medium.

[0035] The alkyd resin is not particularly limited. For example, it is an alkyd resin having a condensate of a polybasic acid and a polyhydric alcohol as a skeleton and modified with a fatty acid. The alkyd resin of this embodiment may be a resin modified with a fatty acid or a hydrogenated product of a fatty acid, an oil or its hydrogenated product, a monovalent acid, etc.

[0036] The oils and fatty acids are linseed oil, castor oil, safflower oil, soybean oil, tall oil, 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 the structural unit derived from the fatty acid contained in the alkyd resin is preferably 35 to 65% by mass in the alkyd resin, more preferably 40 to 60% by mass or less. The printing ink composition containing the alkyd resin with the content of the structural unit derived from the fatty acid within the above range is excellent in compatibility with the above-mentioned solvent, and has good in-flight stability and transferability.

[0038] Also, a part of the fatty acid may be changed to a monobasic acid other than the fatty acid. As other monobasic acids, benzoic acid, p-t-butylbenzoic acid, abietic acid, 12-hydroxystearic acid, etc. can be used in combination.

[0039] The polybasic acids are aromatic dibasic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, alicyclic dibasic acids such as tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 1,4-cyclohexanedicarboxylic acid, aliphatic dibasic acids such as succinic anhydride, maleic anhydride, hymic anhydride, adipic acid, sebacic acid, azelaic acid, fumaric acid, polybasic acids such as trimellitic anhydride, methylcyclohexenetricarboxylic anhydride, etc. The polybasic acids may be used in combination.

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

[0041] The method for producing the alkyd resin is not particularly limited. For example, the method for producing the alkyd resin is a known method such as a transesterification method using oil as a raw material, a fatty acid method using fatty acid as a raw material, etc. As an example, the fatty acid, polybasic acid, and polyhydric alcohol described above are charged into a reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer together with xylene, and the temperature is raised to 240 °C with stirring under a nitrogen atmosphere, and an esterification reaction is carried out. Then, after confirming that the acid value is arbitrary, the reaction is terminated to obtain an alkyd resin.

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

[0043] The polyhydric alcohols include dihydric alcohols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 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-butylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, spiroglycol, isosorbide; trihydric alcohols such as glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol; polyhydric alcohols with three or more hydroxyl groups such as sorbitol and pentaerythritol, etc. The polyhydric alcohols may be used in combination.

[0044] The polybasic acids include aromatic dibasic acids such as phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid; alicyclic dibasic acids such as tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, 1,4-cyclohexanedicarboxylic acid; aliphatic dibasic acids such as oxalic acid, malonic acid, succinic acid, succinic anhydride, maleic anhydride, hymic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid; polybasic acids such as trimellitic anhydride, methylcyclohexenetricarboxylic anhydride, etc. Monobasic acids may be further used in combination. Examples of the 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, benzoic acid, etc.

[0045] The petroleum resin is not particularly limited, and examples thereof include aromatic petroleum resins, aliphatic petroleum resins, dicyclopentadiene-based petroleum resins, and copolymer-based petroleum resins of these raw materials. Commercially available petroleum resins can be used. Examples of 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, Neopolymer S manufactured by ENEOS MATERIALS; Petcol LX, Petcol 120, Petcol 130, Petcol 140 manufactured by Tosoh Corporation. Examples of aliphatic petroleum resins include Quintone A100, Quintone B170, Quintone M100, Quintone R100, Quintone C200H manufactured by Nippon Zeon Co., Ltd.; T-REZ RB100, T-REZ RB093 manufactured by ENEOS MATERIALS. Examples of dicyclopentadiene-based petroleum resins include Quintone 1105, Quintone 1325, Quintone 1340, Quintone 1500 manufactured by Nippon Zeon Co., Ltd.; T-REZ HA085, T-REZ HA103, T-REZ HA105 manufactured by ENEOS MATERIALS. Examples of copolymer-based petroleum resins include Quintone D100, Quintone N180, Quintone P195N, Quintone S100, Quintone S195, Quintone U185, Quintone G100B, Quintone G115, Quintone D200, Quintone E200SN, Quintone N295 manufactured by Nippon Zeon Co., Ltd.; Petro Tack 60, Petro Tack 70, Petro Tack 90, Petro Tack 100V, Petro Tack 90HS manufactured by Tosoh Corporation, etc.

[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 aforementioned solvent is excellent, and the in-flight stability and transferability are good. Also, the physical properties of the coating film are retained in the ink composition. 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. It is only necessary to adjust it to a predetermined ink tack value suitable for metal printing. For example, the content of the resin is preferably 20 to 60% by mass or more, and more preferably 30 to 50% by mass or more in the ink composition. When the content of the resin is within the above range, the ink composition maintains the performance in printing suitability such as transferability and anti-misting property, and also has excellent coating film physical properties.

[0048] <Pigment> The pigment of this embodiment is not particularly limited. Known inorganic pigments or organic pigments for printing inks can be used alone or in combination of two or more.

[0049] The inorganic pigment and the organic pigment preferably have heat resistance, light resistance, and retort resistance. Examples of the inorganic pigment include titanium oxide, silica, carbon black, and the like. Examples of the organic pigment include phthalocyanine-based pigments, azo-based pigments, quinacridone-based pigments, diketopyrrolopyrrole-based pigments, quinophthalone-based pigments, and the like.

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

[0051] <Other components> In addition to the above components, additives usually blended in the ink composition can be blended in the ink composition of this embodiment. For example, a pigment dispersant, an extender pigment, a drier, an acid catalyst, a wax, a viscosity modifier, a storage stabilizer, and the like can be mentioned.

[0052] ·Method for adjusting printing ink The method for preparing the ink composition of this 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 shape of the ink composition of this embodiment varies depending on the types and contents of the resin, pigment, solvent, and additive. For example, the tack value is preferably 4 to 12, and more preferably 5 to 10. Here, the tack value is the value shown by rotating for 1 minute under the conditions of an ink amount of 1.31 cc, a room temperature of 25°C, a roller temperature of 30°C, and a rotation speed of 400 rpm using a digital inkometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.). When the tack value is within the above range, it is excellent in anti-misting property and transferability.

[0054] The flow value is preferably 25 to 50, and more preferably 30 to 45. Here, the flow value is the value shown by measuring the spread diameter value (unit: mm) after 60 seconds at a room temperature of 25°C using a spreadmeter (manufactured by Yasuda Seiki Seisakusho Co., Ltd.). When the flow value is within the above range, it exhibits good transferability.

[0055] · Method for manufacturing a metal printed matter There are no particular restrictions on the printing method of the ink composition of this embodiment, and it can be appropriately selected and used from a dry offset method using a resin relief plate or a waterless lithographic plate, or an offset method using a lithographic plate with water. The film thickness of the ink composition is arbitrary, but it may be in the range of 0.5 to 6 μm. When the film thickness of the ink composition is within the above range, a metal printed matter excellent in in-flight stability and anti-misting property, and showing good coloring power and hiding power can be obtained.

[0056] In addition, examples of the metal printing medium on which the ink composition of this embodiment is printed include, but are not limited to, an aluminum plate, a steel plate, and a coated plate obtained by laminating a polyester film or the like to these. These base materials may be subjected to chemical conversion treatment, plating treatment, and sizing coating, white coating, silver coating, etc. as a base coating.

[0057] The coating method of the substrate in this embodiment includes a step of providing a printed layer with an ink composition on the substrate, a step of applying an overprint varnish on the printed layer, and then a step of performing a curing treatment. Further, the printed and coated article of the present invention includes a printed layer formed by a printing ink composition and an overprint layer formed by an overprint varnish on the substrate. The curing treatment step is preferably heat curing, and the heating conditions are not particularly limited. For example, as the first baking condition, it is heated at a temperature of 180°C to 300°C for about 3 seconds to 90 seconds, and as the second baking, it is heated at a temperature of 180°C to 300°C for about 30 seconds to 150 seconds.

[0058] As the overprint varnish, a thermosetting one is preferably used, and a conventionally known overprint varnish for metal containers can be used without particular limitation. For example, polyester-melamine-based, polyester-epoxy-melamine-based, polyester-acrylic-melamine-based varnishes, etc. can be exemplified. Further, the overprint varnish may be either an aqueous type or a solvent type.

Examples

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

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

[0061] <Solvent> ·AF Solvent No. 4 (paraffin-based hydrocarbon and naphthene-based hydrocarbon, manufactured by Nippon Petrochemical Co., Ltd.) ·AF Solvent No. 6 (paraffin-based hydrocarbon and naphthene-based hydrocarbon, manufactured by Nippon Petrochemical Co., Ltd.) ·D-sol300 (paraffin-based hydrocarbon, manufactured by Mitsubishi Corporation Chemical Co., Ltd.) ·EXXSOLD110 (naphthene-based hydrocarbon, manufactured by ExxonMobil Corporation) · Fine Oxocol 180 (C18: isostearyl alcohol, manufactured by Nissan Chemical Industries, Ltd.) · Tridecanol (C13: tridecanol, manufactured by KH Neochem Co., Ltd.) · N-Geocol 200A (C20: octyldodecanol, manufactured by Shin Nippon Rika Co., Ltd.) · 1-Pentanol (C5: 1-pentanol, manufactured by Nacalai Tesque, Inc.) · LAB (linear alkylbenzene, Mitsui & Co., Ltd.) · Sunnex 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 xylene were charged into a four-necked flask equipped with a stirrer. While refluxing xylene under a nitrogen stream, an esterification reaction was carried out at a temperature of 220°C to 230°C until the acid value reached 5.0 mgKOH / g. After the reaction was completed, xylene was distilled off at 240°C to obtain an alkyd resin having a weight average molecular weight of 8,000 and a number average molecular weight of 2,500. The amount of water removed was 10 parts. (Synthesis of polyester resin) 50 parts of tetrahydrophthalic anhydride, 35 parts of hexanediol, and 15 parts of trimethylolpropane were esterified by a conventional method to obtain a polyester resin having an acid value of 7.0 mgKOH / g, a weight average molecular weight of 4500, and a number average molecular weight of 2,300. (Petroleum resin) · Neopolymer S (manufactured by ENEOS) (weight average molecular weight 1,100)

[0063] <Pigment> · LIONOL BLUE FG-7351 (phthalocyanine blue 15:3, manufactured by Toyo Color Co., Ltd.)

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

[0065] For the ink compositions of Examples 1 to 10 and Comparative Examples 1 to 6, evaluation was carried out according to the following procedures, and the results are shown in Table 1.

[0066] <In-flight stability> 1.31 cc of the ink composition was uniformly placed on the rubber roll of a digital inkometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.), and the in-flight stability was evaluated by measuring the time until the tack value reached the maximum under the conditions of 40 °C and 1200 rpm. Note that the longer the time until the maximum value is reached, the more the solvent detachment from the ink is suppressed, the less the change in the fluidity and viscosity of the ink on the ink roller and the blanket, and it can be said that the in-flight stability is excellent. (Evaluation criteria) A: Reaches the maximum value after 30 minutes B: Reaches the maximum value between 20 minutes and less than 30 minutes C: Reaches the maximum value between 10 minutes and less than 20 minutes D: Reaches the maximum value in less than 10 minutes Note that the evaluations of A, B, and C are practical.

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

[0068] <Transferability during high-speed printing> Using a high-speed printing suitability tester (PM904PT manufactured by SMT Co., Ltd.), 0.2 cc of ink was supplied to the leveling roll. After making it uniform, it was transferred to the test rubber roll, and then transferred onto an aluminum plate at a printing speed of 9.5 m / s. Immediately after that, a thermosetting overprint varnish was applied onto the printed ink layer at a speed of 2 m / s to a film thickness of 13 μm. Thereafter, it was baked at 200 °C for 3 minutes to produce a printed coating film. A: The ink composition is transferred to the substrate without unevenness and has good ink adhesion. B: Slight unevenness in ink transfer and / or bleeding at the edge part of printing are observed. C: Some unevenness in ink transfer and / or bleeding at the edge part of printing are observed. D: Obvious unevenness in ink transfer and / or bleeding at the edge part of printing are observed. Note that the evaluations of being practical are A, B, and C.

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

[0070]

Table 1

[0071] The formulation designs of the examples and comparative examples are as follows. (Examples 1 to 10) It contains a resin, a pigment, and a solvent. The solvent includes a paraffinic hydrocarbon and / or a naphthenic hydrocarbon, and a higher alcohol having 6 or more carbon atoms. (Comparative Examples 1, 2, 4, 5) Compared with the composition of the examples, it does not contain a higher alcohol having 6 or more carbon atoms. (Comparative Example 3) It does not contain paraffinic hydrocarbons and naphthenic hydrocarbons as compared with the composition of the example. (Comparative Example 6) It does not contain paraffinic hydrocarbons and / or naphthenic hydrocarbons and higher alcohols having 6 or more carbon atoms as compared with the composition of the example.

[0072] As shown in Table 1, when the ink composition for metal printing described in the examples of the present invention was used, an ink composition for metal printing excellent in in-flight stability, misting resistance, and transferability during high-speed printing could be obtained as compared with the case where the ink composition for metal printing of the comparative example was used.

Claims

1. The ink composition for metal printing contains a resin, a pigment, and a solvent, wherein the resin includes a polyester resin and / or a petroleum resin, the solvent includes a paraffinic hydrocarbon and / or a naphthenic hydrocarbon, and a higher alcohol having 6 to 30 carbon atoms, and the mass ratio of the total amount of the paraffinic hydrocarbon and the naphthenic hydrocarbon to the higher alcohol having 6 to 30 carbon atoms is 40 / 60 to 98 / 2.

2. 2. The ink composition for metal printing according to claim 1, wherein the mass ratio of the total amount of the paraffinic hydrocarbons and naphthenic hydrocarbons to the higher alcohol having 6 to 30 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 10 to 20 carbon atoms.

4. 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 to 30 carbon atoms is 50 to 100 mass% based on the total content of the solvent.

5. 2. The ink composition for metal printing according to claim 1, wherein the polyester resin contains an alkyd resin having a content of fatty acid-derived structural units of 35 to 65 mass%.

6. A metallic print comprising a printed layer formed on a metallic medium and comprising the ink composition for metallic printing according to any one of claims 1 to 5, and an overprint layer formed on the printed layer.

7. A method for producing a metal printed product, comprising: forming a printed layer on a metal medium by dry offset printing or offset printing of the ink composition for metal printing according to any one of claims 1 to 5; and applying an overprint varnish onto the printed layer to form an overprint layer.

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