Printing ink composition for seamless can and printed and coated seamless can

Abstract

To provide a printing ink composition for a seamless can, which reduces the amount used of a mineral oil solvent, with printability, such as excellent misting resistance and on-press stability, and with excellent suitability for a solvent-based overprint varnish; and to provide a printed and coated seamless can.SOLUTION: Provided is a printing ink composition for a seamless can, containing an alkyd resin, a pigment and a solvent, and in the printing ink composition for a seamless can, a fatty acid content in the alkyd resin is 41 to 60 mass%, the solvent includes a solvent A and a solvent B, the solvent A being a linear α-olefin having 14 to 18 carbon atoms and the solvent B being an alcohol having 10 to 20 carbon atoms and / or a fatty acid ester having 10 to 20 carbon atoms, the blending ratio (mass ratio) of the solvent A and the solvent B is 50 / 50 to 95 / 5, and the total content of the solvent A and the solvent B is 80 to 100 mass% relative to the total content of the solvent.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a printing ink composition for seamless cans which reduces the amount of mineral oil solvent used and has excellent printability such as excellent misting resistance and on-press stability, as well as excellent suitability for solvent-type overprint varnishes; a method for coating a substrate with the ink; and a printed and coated seamless can. [Background technology]

[0002] Metal containers as packaging containers are used for various purposes. Among metal containers, seamless cans are produced by a method in which a metal plate is first punched out, then processed into a cylindrical shape with a bottom through processes such as ironing, and the cylindrical body with a bottom is printed and painted, and the can body is finished by processing such as necking and flanging.

[0003] Seamless cans are widely used as packaging containers for fruit juices, soft drinks, carbonated drinks, alcoholic beverages such as beer, and foods. The outer surface of seamless cans is printed or painted for decoration to enhance the product value, corrosion prevention, etc.

[0004] In printing on seamless cans, printing ink is supplied from an ink fountain, transferred to the printing area of ​​the plate via multiple rolls, and then transferred to a blanket, after which printing is performed on the body of the seamless can. A dry offset method is used for printing on seamless cans, and a resin letterpress plate is usually used.

[0005] Petroleum-based solvents such as aromatic hydrocarbons and aliphatic saturated hydrocarbons have been used as solvents for printing ink compositions for seamless cans. For example, Patent Documents 1 and 2 disclose printing inks for seamless cans that use alkylbenzene as a solvent.

[0006] On the other hand, in recent years, various industries and sectors have been working to reduce the environmental impact from various perspectives, with the goal of protecting the global environment. For example, the mineral oil solvents contained in inks are known to be genotoxic and mutagenic, so there are efforts to reduce the environmental impact by reducing the use of mineral oil solvents. Specific examples of mineral oil solvents include mineral oil aromatic hydrocarbons (MOAH) containing 1 to 7 aromatic rings and mineral oil saturated hydrocarbons (MOSH) containing 16 to 35 carbon atoms.

[0007] Among the methods for replacing mineral oil solvents, examples using highly hydrophilic dilutable components include Patent Document 3 and Patent Document 4. However, while inks using these dilutable solvents are suitable for aqueous overprint varnishes, they are not suitable for solvent-based overprint varnishes. In addition, they generate a large amount of mist during printing, causing stains on the printing and coating cans, worsening the working environment. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2023-89841 A [Patent Document 2] JP 2018-58956 A [Patent Document 3] Japanese Patent Application Publication No. 03-273068 [Patent Document 4] Japanese Patent Application Publication No. 04-106166 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention aims to provide a printing ink composition for seamless cans which reduces the amount of mineral oil solvent used, and which has excellent printability such as excellent misting resistance and on-press stability, and excellent suitability for solvent-type overprint varnishes; a method for coating a substrate with the ink; and a printed and coated seamless can. [Means for solving the problem]

[0010] As a result of extensive research, the inventors have found that in a printing ink composition for seamless cans containing an alkyd resin, a pigment, and a solvent, by adjusting the fatty acid content in the alkyd resin and the ratio of the linear alpha olefin, which is the solvent in the ink composition, to an alcohol and / or fatty acid ester in a specified ratio, it is possible to reduce the amount of mineral oil solvent used and to achieve excellent printing suitability and suitability as a solvent-type overprint varnish.

[0011] That is, the present invention is characterized in that the content of fatty acid in the alkyd resin is 41 to 60% by mass.

[0012] The present invention further relates to a printing ink composition for seamless cans, which contains solvent A and solvent B, wherein solvent A is a linear α-olefin having 14 to 18 carbon atoms, and solvent B is an alcohol having 10 to 20 carbon atoms and / or a fatty acid ester having 10 to 20 carbon atoms.

[0013] Furthermore, the present invention relates to a printing ink composition for seamless cans, characterized in that a blending ratio (mass ratio) of the solvent A and the solvent B is 50 / 50 to 95 / 5, and a total content of the solvent A and the solvent B is 80 to 100 mass% with respect to the total content of the solvents.

[0014] The present invention also relates to a method for coating a substrate, which comprises printing the above-mentioned printing ink composition for seamless cans on a metal printing medium, applying an overprint varnish thereto, and curing the varnish.

[0015] The present invention also relates to a printed and coated seamless can comprising a printed layer formed on a metal printing medium from a printing ink composition for seamless cans, and an overprint layer formed from an overprint varnish. Effect of the Invention

[0016] According to the present invention, it is possible to provide a printing ink composition for seamless cans, which reduces the amount of mineral oil solvent used, exhibits excellent suitability even when a solvent-type overprint varnish is used, and exhibits good printability, and a method for coating a substrate with the printing ink composition for seamless cans. The printing ink composition for seamless cans and the coating method can improve the working environment during printing and reduce the environmental load. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, one embodiment of the printing ink composition for seamless cans of the present invention will be described. Note that the present invention is not limited to the following embodiment, and can be practiced with appropriate modifications within the scope of the present invention.

[0018] (Printing ink composition for seamless cans) The printing ink composition for seamless cans (hereinafter also referred to as the ink composition) of this embodiment contains an alkyd resin, a pigment, and a solvent as essential components. Each component will be described below.

[0019] <Alkyd resin> The alkyd resin of the present embodiment functions as a binder component, and is a resin having a skeleton made of a condensate of a polybasic acid and a polyhydric alcohol, which is modified with a fatty acid.

[0020] The content of fatty acid contained in the alkyd resin is 41% by mass or more and 60% by mass or less, preferably 43% by mass or more and 58% by mass or less, and more preferably 45% by mass or more and 55% by mass or less, in the alkyd resin. An ink composition containing an alkyd resin having a fatty acid content within the above range has excellent misting resistance and on-machine stability. The fatty acid preferably has an iodine value of not more than 100. A fatty acid having an iodine value of not more than 100 is preferred because the use of such a fatty acid makes it difficult for a particular odor due to components derived from the fatty acid to be generated, and improves the flavor of the contents of the seamless can. Examples of fatty acids having an iodine value of 100 or less include natural or synthetic fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, and ricinoleic acid; coconut oil fatty acid, castor oil fatty acid, palm oil fatty acid, etc. These fatty acids may be used alone or in combination of two or more kinds, but from the viewpoint of fluidity and on-machine stability, it is preferable to use capric acid, lauric acid, myristic acid, palmitic acid, and coconut oil fatty acid, and it is more preferable to use coconut oil fatty acid.

[0021] In addition, a part of the fatty acid derived from fatty acids or oils may be replaced with a monobasic acid other than fatty acids. Examples of other monobasic acids that can be used include benzoic acid, pt-butylbenzoic acid, abietic acid, hydrogenated abietic acid, and 12-hydroxystearic acid.

[0022] Examples of polybasic acids that can be used include dibasic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride, adipic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and maleic anhydride, and tribasic acids such as trimellitic anhydride and methylcyclohexene tricarboxylic anhydride, and these may be used in combination.

[0023] Examples of polyhydric alcohols that can be used include 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, and these may be used in combination.

[0024] The styrene-equivalent weight average molecular weight (Mw) of the alkyd resin is preferably 5,000 to 20,000, more preferably 7,000 to 18,000. The number average molecular weight (Mn) is preferably 2,200 to 6,500, more preferably 2,500 to 6,000. By having Mw and Mn within the above ranges, the ink composition has a moderate cohesive force and is likely to obtain sufficient coating strength. In addition, the viscosity of the alkyd resin becomes appropriate, the ink composition is easily adjusted to a predetermined shape, and the ink composition has excellent stability and flowability on the machine. In the present embodiment, the weight average molecular weight and the number average molecular weight are values ​​measured by gel permeation chromatography (GPC).

[0025] The acid value of the alkyd resin is not particularly limited. For example, the acid value is preferably 0.1 mgKOH / g or more and 30 mgKOH / g or less, and more preferably 1.0 mgKOH / g or more and 15 mgKOH / g or less. By having the acid value within the above range, the ink composition can ensure proper fluidity and can minimize the influence on transferability. In this embodiment, the acid value is defined as the number of mg of potassium hydroxide required to neutralize the free acid contained in 1 g of resin. The unit is mgKOH / g.

[0026] The method for producing the alkyd resin is not particularly limited. For example, known methods such as the transesterification method using oil as a raw material and the fatty acid method using fatty acid as a raw material can be used for producing the alkyd resin. As an example, the fatty acid described above, polybasic acid, and polyhydric alcohol are charged together with xylene in a reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer, and the temperature is raised to 240° C. while stirring under a nitrogen atmosphere to carry out an esterification reaction. After confirming that the acid value is an arbitrary value, the reaction is terminated to obtain an alkyd resin.

[0027] The content of the alkyd resin in the ink composition is adjusted appropriately depending on the type and purpose, but is preferably 20 to 45% by mass, more preferably 25 to 40% by mass. By having the alkyd resin content within the above range, the ink composition exhibits good workability and printability, and is also excellent in film strength and processability.

[0028] Furthermore, in addition to the above alkyd resin, other resins used in normal printing inks can be used in combination. That is, known resins compatible with the alkyd resin can be used alone or in combination depending on the required performance such as ink shape, printability, coating film properties, etc. Specific examples include rosin-modified phenolic resins, polyester resins, petroleum resins, epoxy resins, ketone resins, rosin-modified maleic acid resins, melamine resins, and benzoguanamine resins.

[0029] <Pigments> The pigment of the present embodiment is not particularly limited. Known inorganic or organic pigments for printing inks can be used alone or in combination.

[0030] The inorganic pigment and the organic pigment are preferably those having heat resistance, light resistance, and retort treatment resistance. The inorganic pigment is titanium oxide, silica, carbon black, etc. The organic pigment is phthalocyanine pigment, azo pigment, quinacridone pigment, diketopyrrolopyrrole pigment, quinophthalone pigment, threne pigment, dioxazine pigment, isoindolinone pigment, etc.

[0031] The pigment concentration is appropriately adjusted depending on the type and purpose. For example, the content of titanium oxide, which exhibits white color, in the ink composition is preferably 10 to 70 mass%, more preferably 20 to 60 mass%, the content of carbon black, which exhibits black color, is preferably 10 to 50 mass%, more preferably 20 to 40 mass%, and the content of organic pigments is preferably 10 to 50 mass%, more preferably 15 to 40%. By having the pigment content within the above ranges, the ink composition exhibits good coloring power and hiding power, and is also excellent in dispersion stability.

[0032] <Solvent> The solvent contains a linear α-olefin having 14 to 18 carbon atoms (solvent A) and an alcohol having 10 to 20 carbon atoms and / or a fatty acid ester having 10 to 20 carbon atoms (solvent B). By incorporating these solvents, the ink composition of this embodiment can reduce the amount of mineral oil solvent used, and has excellent suitability for solvent-type overprint varnishes and anti-misting properties.

[0033] Linear alpha olefin with carbon number 14 to 18 (solvent A) Examples of linear α-olefins having 14 to 18 carbon atoms include 1-octadecene (C18), 1-hexadecene (C16), and 1-tetradecene (C14). These may be used alone or in combination of two or more. If the carbon number is less than C14, the solvent tends to dry on the printing roll, resulting in poor on-machine stability. On the other hand, if the carbon number is greater than C18, the misting resistance is poor.

[0034] The content of the linear alpha olefin having 14 to 18 carbon atoms in the ink composition is preferably 15 to 35 mass %, more preferably 20 to 30 mass %. When the content of the linear alpha olefin having 14 to 18 carbon atoms is within the above range, the ink composition exhibits good misting resistance and is excellent in suitability for use as a solvent-type overprint varnish.

[0035] Alcohol with 10 to 20 carbon atoms (solvent B) The alcohol having 10 to 20 carbon atoms is not particularly limited. For example, the alcohol having 10 to 20 carbon atoms is higher alcohol such as isooctadecyl alcohol (C18), tridecanol (C13), dodecyl alcohol (C12), 1-decanol (C10), etc. These may be used alone or in combination of two or more. If the carbon number is less than C10, the solvent tends to dry on the printing roll, resulting in poor on-machine stability. On the other hand, if the carbon number is more than C20, the misting resistance is poor.

[0036] Fatty acid ester with 10 to 20 carbon atoms (solvent B) The fatty acid ester having 10 to 20 carbon atoms is not particularly limited. For example, fatty acid ester having 10 to 20 carbon atoms is 2-ethylhexyl laurate (C20), isobutyl laurate (C16), methyl laurate (C13), methyl caprate (C11), etc. These may be used alone or in combination of two or more. If the carbon number is less than C10, the solvent tends to dry on the printing roll, resulting in poor on-machine stability. On the other hand, if the carbon number is more than C20, the anti-misting properties are poor.

[0037] The content of solvent B in the ink composition is preferably 2 to 15% by mass, more preferably 3 to 10% by mass. When the content of solvent B is within the above range, the ink composition exhibits good misting resistance. In addition, since the compatibility between the alkyd resin and the solvent component is good, the ink tack value can be easily adjusted to be suitable for printing on seamless cans produced at high speed.

[0038] The blending ratio of the solvent A to the solvent B is preferably 50 / 50 to 95 / 5, and more preferably 70 / 30 to 90 / 10. By having the blending ratio within the above range, it is possible to achieve both anti-misting properties and on-machine stability.

[0039] Examples of solvents other than the solvent A and the solvent B include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polyethylene oxide-propylene oxide (a copolymer of ethylene oxide and propylene oxide), poly(methyl-ethylene) glycol, and polybutylene glycol; polyoxypropylene ether of butyl alcohol, polyoxyethylene ether of 2-ethyl-1-hexanol, polyoxyethylene ether of 2-ethyl-1-heptanol, polyoxyethylene ether of 2-ethyl-1-octanol, lauryl alcohol, and the like. Examples of polyalkylene glycol ethers include polyoxyethylene ether of alcohol (dodecan-1-ol), polyoxyethylene ether of cetyl alcohol (hexadecan-1-ol), polyoxyethylene ether of stearyl alcohol (1-octadecanol), polyoxyethylene ether of oleyl alcohol ((E)-octadec-9-en-1-ol), and polyoxyethylene ether of a mixture of stearyl alcohol and cetyl alcohol (cetylstearyl alcohol); and lactam solvents such as N-methyl-2-pyrrolidone and 2-pyrrolidone.

[0040] In the total content of the solvents, the ratio of the total content of the solvent A and the solvent B is preferably 80 to 100%, and more preferably 90 to 100%. When the ratio of the total content of the solvent A and the solvent B is within the above range, excellent misting resistance is exhibited, and excellent suitability for a solvent-type overprint varnish is achieved.

[0041] The content of the solvent in the ink composition is adjusted appropriately depending on the type and purpose, but is preferably 20 to 45% by mass, more preferably 25 to 40% by mass. By having the content of the solvent within the above range, the ratio of the alkyd resin and the solvent in the ink composition becomes good, and the ink tack value can be easily adjusted to be suitable for printing on seamless cans produced at high speed.

[0042] <Other ingredients> The ink composition of the present embodiment may contain, as other components, additives that are typically added to ink compositions, such as a pigment dispersant, an extender pigment, a dryer, an acid catalyst, a wax, a viscosity modifier, and a storage stabilizer.

[0043] 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.

[0044] The form of the ink composition of this embodiment varies depending on the type and content of alkyd resin, pigment, solvent, and additives. For example, for dry offset printing using a relief plate, it is preferable to adjust the tack value (JIS K5701-1) to 4 to 12 and the flow value (JIS K5701-1) to 27 to 47.

[0045] The printing ink composition for seamless cans of the present invention can be used in a dry offset method using a resin letterpress plate or a dry offset method using a waterless flat plate. The thickness of the ink composition is not limited, but may be in the range of 0.5 to 6 μm.

[0046] The metal printing medium on which the printing ink composition for seamless cans of the present invention is printed includes, but is 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, and size coating, white coating, silver coating, etc. as base coating.

[0047] The method for coating a substrate in this embodiment includes a step of providing a printed layer on a substrate using a printing ink composition for seamless cans, a step of applying an overprint varnish on the printed layer, and a step of subsequently performing a curing treatment. The printed coated product of the present invention includes a printed layer formed on a substrate using a printing ink composition for seamless cans, and an overprint layer formed on the substrate using an overprint varnish. The step of applying the overprint varnish is preferably a step of applying the varnish by a wet-on-wet method. The step of performing a curing treatment is preferably heat curing, and the heating conditions are not particularly limited. As an example, the first baking conditions include heating at a temperature of 180°C to 300°C for about 3 to 90 seconds, and the second baking conditions include heating at a temperature of 180°C to 300°C for about 30 to 150 seconds.

[0048] The overprint varnish is preferably a thermosetting one, and conventionally known ones can be used without any particular limitation. For example, polyester-melamine type, polyester-epoxy-melamine type, polyester-acrylic-melamine type varnish, etc. can be exemplified. In addition, the overprint varnish may be either a water-based type or a solvent-based type, and suitable overprint varnish suitability can be obtained. EXAMPLES

[0049] The present invention will be described below based on examples and comparative examples, but the present invention is not limited to these examples. In the following, "parts" and "%" are all Also, the units are "parts by mass" and "% by mass".

[0050] (Alkyd resin (1)) 55 parts of coconut oil fatty acid, 26 parts of isophthalic acid, 29 parts of pentaerythritol, and 10 parts of xylol were charged into a four-necked flask equipped with a stirrer, and esterification reaction was carried out at a temperature of 220°C to 230°C while circulating xylol under a nitrogen stream until the acid value reached 5.0 mgKOH / g. After the reaction was completed, xylol was distilled off at 240°C to obtain an alkyd resin (1) with a weight average molecular weight of 9,200 and a number average molecular weight of 3,100. The amount of dehydration was 10 parts.

[0051] (Alkyd resin (2)) 45 parts of coconut oil fatty acid, 33 parts of isophthalic acid, 33 parts of pentaerythritol, and 10 parts of xylol were charged into a four-neck flask equipped with a stirrer, and esterification reaction was carried out at a temperature of 220°C to 230°C while circulating xylol under a nitrogen stream until the acid value reached 5.0 mgKOH / g. After the reaction was completed, xylol was distilled off at 240°C to obtain an alkyd resin (2) with a weight average molecular weight of 15,500 and a number average molecular weight of 5,500. The amount of dehydration was 10 parts.

[0052] (Alkyd resin (3)) 35 parts of coconut oil fatty acid, 38 parts of isophthalic acid, 38 parts of pentaerythritol, and 10 parts of xylol were charged into a four-neck flask equipped with a stirrer, and esterification reaction was carried out at a temperature of 220°C to 230°C while circulating xylol under a nitrogen stream until the acid value reached 5.0 mgKOH / g. After the reaction was completed, xylol was distilled off at 240°C to obtain an alkyd resin (3) with a weight average molecular weight of 20,500 and a number average molecular weight of 6,700. The amount of dehydration was 11 parts.

[0053] (Alkyd resin (4)) 65 parts of coconut oil fatty acid, 19 parts of isophthalic acid, 25 parts of pentaerythritol, and 10 parts of xylol were charged into a four-neck flask equipped with a stirrer, and esterification reaction was carried out at a temperature of 220°C to 230°C while circulating xylol under a nitrogen stream until the acid value reached 5.0 mgKOH / g. After the reaction was completed, xylol was distilled off at 240°C to obtain an alkyd resin (4) with a weight average molecular weight of 4,500 and a number average molecular weight of 2,100. The amount of dehydration was 9 parts.

[0054] The formulations and parameters of the alkyd resins (1) to (4) are shown in Table 1.

[0055] [Table 1]

[0056] Using the obtained alkyd resins (1) to (4), printing ink compositions for seamless cans of Examples and Comparative Examples were prepared according to the formulations shown in Tables 2 and 3. The tack value was set in the range of 5.5 to 6.5. The materials listed in the table are as follows. The numbers in parentheses indicate the number of carbon atoms. Pigment: Phthalocyanine Blue 15:3 ("LIONOL BLUE FG-7351" manufactured by Toyo Color Co., Ltd.) Linear alpha olefin (C18): 1-octadecene ("Linearene 18" manufactured by Idemitsu Kosan Co., Ltd.) Linear alpha olefin (C16): 1-hexadecene ("Linearene 16" manufactured by Idemitsu Kosan Co., Ltd.) Linear alpha olefin (C12): 1-dodecene ("Linearene 12" manufactured by Idemitsu Kosan Co., Ltd.) Linear alpha olefins (C20-C24): a mixture of 1-eicosene, 1-docosene, and 1-tetracosene ("Linearene 2024" manufactured by Idemitsu Kosan Co., Ltd.) Alcohol (C18): Isooctadecanol (Nissan Chemical Co., Ltd. "Fine Oxocol 180A") Alcohol (C16): 2-Hexyldecyl alcohol (Nissan Chemical Co., Ltd. "Fine Oxocol 1600") Alcohol (C8): Octyl alcohol (Kao Corporation "Kalcol 0898") Alcohol (C24): 2-Decyltetradecanol ("N-Jecol 240A" manufactured by New Japan Chemical Co., Ltd.) Fatty acid ester (C16): Isobutyl laurate (TOSOLV-LIB, manufactured by Toshin Yushi Co., Ltd.) Fatty acid ester (C13): Methyl laurate (TOENOL#2012-95, manufactured by Toei Chemical Co., Ltd.) Fatty acid ester (C9): Methyl caprylate (TOENOL#2008-95, manufactured by Toei Chemical Co., Ltd.) Fatty acid ester (C26): Ethylhexyl stearate (TOSOLV-STO, manufactured by Toshin Yushi Co., Ltd.) · Polypropylene glycol: "Sunnex PP400" manufactured by Sanyo Chemical Industries, Ltd. · Dispersant: Phthalocyanine derivative "SOLSPERSE 5000" manufactured by Lubrizol Japan Ltd. · Acid catalyst: Metal salt of dinonylnaphthalene sulfonic acid "K-SPERSE 131" manufactured by King Industries

[0057]

Table 2

Table 3

[0058] (Evaluation) The ink compositions of Examples 1 to 9 and Comparative Examples 1 to 12 were evaluated in the following manner, and the results are shown in Table 2 and Table 3.

[0059] (In-flight stability) After stretching 0.05 cc of the seamless can printing ink composition on a four-segment roll using an RI tester, the ink was transferred onto an aluminum plate. Then, the roll was continuously rotated without replenishing the ink, printing was performed on the aluminum plate every 10 minutes, and the time until the ink no longer transferred was examined and evaluated as follows. 〇: The ink transfers even after 120 minutes △ - 〇: The ink no longer transfers between 90 minutes and less than 120 minutes △: The ink no longer transfers between 60 minutes and less than 90 minutes ×: The ink no longer transfers in less than 60 minutes

[0060] (Anti-misting property) 2.6 cc of the adjusted ink composition was taken and applied to the rotating roller of an incotester. After leveling it uniformly, it was rotated at 2,400 rpm for 5 minutes. During this time, a 10 cm square plate was placed under the roller, and the amount of ink splashed onto it was compared. The measurement was performed with the roller maintained at 40°C. Evaluation criteria ○: The change in mass of the plate before and after the measurement is less than 20 mg, and will not cause any problems during production. △-〇: The change in mass of the plate before and after measurement is 20 mg or more but less than 50 mg. Some ink has scattered, but the plate can still be used for production. △: The change in mass of the plate before and after the measurement is 50 mg or more but less than 100 mg, which will hinder production. ×: The change in mass of the plate before and after the measurement is 100 mg or more, which significantly impedes production.

[0061] (Suitable for solvent-based overprint varnish) The prepared ink composition was applied to a seamless aluminum can, and a solvent-type overprint varnish was applied on the ink composition. The ink composition was then baked for 3 minutes at 200°C to produce a printed coating film. The printed coating film was visually evaluated for the state of aggregation of the ink composition and the presence or absence of repellency of the applied overprint varnish. ○: No aggregation or repellency occurred △: A small amount of aggregation and / or repellency occurred. ×: Aggregation and / or repellency occurs.

[0062] As is clear from Tables 2 and 3, by using the printing ink compositions for seamless cans described in the examples of the present invention, even ink compositions that do not contain mineral oil solvents could be obtained that have excellent on-machine stability and misting resistance and are suitable for use as solvent-type overprint varnishes.

Claims

1. A printing ink composition for seamless cans, comprising an alkyd resin, a pigment, and a solvent, The content of fatty acid in the alkyd resin is 41 to 60% by mass, The solvent includes a solvent A and a solvent B, Solvent A is a linear alpha olefin having 14 to 18 carbon atoms; the solvent B is an alcohol having 10 to 20 carbon atoms and / or a fatty acid ester having 10 to 20 carbon atoms, The mixing ratio (mass ratio) of the solvent A to the solvent B is 50 / 50 to 95 / 5, The total content of the solvent A and the solvent B is 80 to 100 mass% based on the total content of the solvents. A printing ink composition for seamless cans.

2. 2. The printing ink composition for seamless cans according to claim 1, wherein the iodine value of the fatty acid constituting the alkyd resin is 100 or less.

3. 3. A method for coating a substrate, comprising providing a printing layer on a metal printing medium using the printing ink composition for seamless cans according to claim 1 or 2, applying an overprint varnish onto said printing layer, and then carrying out a curing treatment.

4. 3. A printed and coated seamless can comprising a printed layer formed on a metal printing medium using the printing ink composition for seamless cans according to claim 1 or 2, and an overprint layer formed using an overprint varnish.

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