Metal printing ink composition

Abstract

To provide a metal printing ink composition which can reduce occurrence of misting during printing and also can maintain good impact resistance even after a metal printed matter after printing is subjected to retort treatment.SOLUTION: A metal printing ink composition should be used comprising carbon black, a resin, and a solvent. The carbon black is neutral carbon black. The solvent has a solubility parameter (sp value) of less than 10.0 (cal / cm3)1 / 2. The composition comprises at least one selected from the group consisting of compounds represented by the general formula (1) in the figure. In the general formula (1), each A is independently a C2-4 alkylene group that may be branched, R is a C1-13 alkyl group that may have a branched and / or cyclic structure, and n is an integer from 2 to 8.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an ink composition for metal printing.

Background Art

[0002] For printing on the outer surface of metal materials such as galvanized or tinned iron sheets, aluminum plates, or metal cans made of these metal materials, an ink composition for metal printing is used, which mainly uses a binder resin such as alkyd resin, polyester resin, epoxy resin, and an organic solvent such as mineral oil or higher alcohol as vehicle components.

[0003] In addition, in order to improve the adhesion, flex resistance, impact resistance, abrasion resistance, etc. of the ink coating film on these printing surfaces, coating by overprint varnish is generally performed. As these overprint varnishes, solvent-type ones composed of a binder resin such as alkyd resin, polyester resin, acrylic resin, epoxy resin, a curing agent such as melamine resin, benzoguanamine resin, and an organic solvent such as mineral oil or cellosolve type have been widely used.

[0004] When printing on the outer surface of metal, after printing the ink using an offset printing machine, a dry offset printing machine, etc., the overprint varnish is applied wet-on-wet on the ink film using a coater, etc., and then baking is performed at 150 to 280°C.

[0005] However, in recent years, due to the problem of air pollution caused by solvents and the hygiene or safety aspects in the printing work environment, in the field of metal printing as well, it has become common to adopt water-based overprint varnishes instead of the conventionally used solvent-type overprint varnishes. However, when a water-based overprint varnish is applied onto the ink coating film of a conventional ink composition for metal printing, phenomena such as repulsion of the water-based overprint varnish and penetration of the water-based overprint varnish into the ink film occur. As a result, there has been a problem that the quality such as gloss or adhesion of the coating film is significantly deteriorated. Therefore, in the ink composition as well, it has been required to have excellent suitability for water-based overprint varnishes.

[0006] As a method for improving the suitability for such water-based overprint varnishes, for example, Patent Document 1 proposes the use of alkylene glycol solvents having 4 to 8 carbon atoms, Patent Document 2 proposes the use of polyoxyalkylene glycol solvents, Patent Document 3 proposes the use of polyoxyalkylene alkyl ether organic solvents, and Patent Document 4 proposes the use of polyoxyalkylene alkyl ester solvents, respectively. The organic solvents used in these ink compositions are effective in improving the suitability of the ink composition for water-based overprint varnishes, but there is room for improvement in terms of being prone to misting during printing.

[0007] Also, depending on the use of metal printed matter, for example, retort processing, that is, pressurization and heat treatment with steam or hot water at 100°C or higher, may be performed for purposes such as sterilization for two-piece cans or three-piece cans used for beverages such as coffee and tea or canned goods. When such processing is carried out, the printed film of the metal printed matter becomes vulnerable, and the impact resistance, which is the performance of maintaining the printed film when an impact is applied to the printed surface, may be significantly reduced.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a metal printing ink composition that can reduce the occurrence of misting during printing and maintain good impact resistance even after the printed metal product has been subjected to retort processing.

Means for Solving the Problems

[0010] As a result of intensive studies to solve the above problems, the present inventors have found that in a black ink using carbon black as a coloring pigment, particularly by using neutral carbon black and a hydrophobic solvent having a solubility parameter (sp value) of less than 10.00 (cal / cm 3 ) 1 / 2 the above problems can be solved, and the present invention has been completed. Specifically, the present invention provides the following.

[0011] (1) The present invention is a metal printing ink composition comprising carbon black, a resin, and a solvent, wherein the carbon black includes neutral carbon black, and the solvent has a solubility parameter (sp value) of less than 10.00 (cal / cm 3 ) 1 / 2 and contains at least one selected from the group consisting of compounds represented by the following general formula (1).

Chemical Formula

[0012] (2) The present invention also provides a metal printing ink composition according to item (1), wherein the resin is an alkyd resin.

[0013] (3) The present invention also provides a metal printing ink composition according to item (2), wherein the mass average molecular weight of the alkyd resin is less than 10,000.

[0014] (4) The present invention also provides a metal printing ink composition according to item (2) or (3), wherein the alkyd resin has a pentaerythritol skeleton.

[0015] (5) The present invention also provides a metal printing ink composition according to any one of items (1) to (4), wherein the divalent group represented by AO in the general formula (1) is an oxypropylene group.

[0016] (6) The present invention also provides a metal printing ink composition according to any one of items (1) to (5), further containing an alkanolamine.

[0017] (7) The present invention also provides a metal printing ink composition according to any one of items (1) to (6), further containing a rosin-modified resin.

Advantages of the Invention

[0018] According to the present invention, there is provided a metal printing ink composition capable of reducing the occurrence of misting during printing and maintaining good impact resistance even after the printed metal product has been subjected to retort treatment.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, an embodiment of the ink composition for metal printing of the present invention will be described. Note that the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the present invention.

[0020] The ink composition for metal printing of the present invention (hereinafter, appropriately abbreviated as "the ink composition of the present invention") is for metal printing and is preferably applicable to printing by a so-called dry offset printing method using a relief plate as a printing plate or an offset printing method using a lithographic plate as a printing plate. However, it can be applied to all printing methods commonly used in metal printing. Further, in the ink composition of the present invention, the occurrence of misting during printing is suppressed, and the occurrence of contamination around the printing machine due to minute ink droplets generated during printing is suppressed. Furthermore, the printed film formed by baking after printing with the ink composition of the present invention has good impact resistance even after undergoing retort treatment. Therefore, the ink composition of the present invention is preferably applicable not only to general metal prints but also to printing on metals that require retort treatment, such as two-piece cans and three-piece cans used for beverages such as coffee and tea and canned goods.

[0021] The ink composition of the present invention comprises carbon black, a resin, and a solvent. This carbon black particularly includes a neutral one, and is characterized by including a glycol monoether-based solvent represented by the general formula (1) having a specific solubility parameter (sp value) as the solvent. Hereinafter, each component will be described.

[0022] [Carbon Black] The ink composition of the present invention contains carbon black as a coloring pigment. Various commercially available carbon blacks exhibit acidic, neutral, or alkaline properties depending on the differences in their surface functional groups. In the present invention, particularly neutral carbon black is used. The neutral carbon black in the present invention refers to a carbon black having a pH in the range of 6.0 or more and 9.5 or less. The reason for using such neutral carbon black in the present invention is based on the finding of the inventors that by using neutral carbon black instead of acidic carbon black that has been used in ink compositions for metal printing, the impact resistance of the ink film formed on the metal after retort treatment can be improved.

[0023] The pH of carbon black is determined by measuring a mixed solution of carbon black and distilled water with a glass electrode pH meter. Specifically, 1 g of the carbon black to be measured is added to 20 mL of distilled water (pH 7.0) from which carbonic acid has been removed, and mixed with a magnetic stirrer to prepare an aqueous suspension. The pH is measured at 25 °C using a glass electrode (German Industrial Standard DIN ISO 787 / 9).

[0024] As the addition amount of carbon black, about 5 to 50% by mass with respect to the whole ink composition is exemplified, but it is not particularly limited. In addition to carbon black, pigments of other colors or ink compositions of other colors may be added to the ink composition as complementary colors.

[0025] [Resin] As the resin used in the ink composition of the present invention, those that have been used in ink compositions for metal printing can be listed without particular limitation. Among these resins, alkyd resin is preferably used in the ink composition of the present invention. Also, a rosin-modified resin may be combined with the alkyd resin and used. Next, these resins will be described.

[0026] An alkyd resin is a polycondensate of a polyhydric alcohol and a polybasic acid and is a type of polyester. However, it can also be prepared by performing polycondensation with vegetable and animal oils and / or their fatty acids in addition to these. At this time, the vegetable and animal oils are transesterified with the polyhydric alcohol to become fatty acids and are incorporated into the structure of the alkyd resin. The ratio derived from the fatty acids of the vegetable and animal oils in the alkyd resin is called the oil length, and the oil length of the alkyd resin used in the present invention is preferably 20 to 50% by mass. Note that an oil-free alkyd, which is an alkyd resin that does not contain the fatty acid component of vegetable and animal oils, may be used.

[0027] As the alkyd resin used in the present invention, those having a pentaerythritol skeleton in the molecule are preferably mentioned. By using an alkyd resin having such a skeleton, the impact resistance after retort treatment in the printed film can be improved, which is preferable. Such an alkyd resin is prepared by using pentaerythritol as a polyhydric alcohol. Note that the alkyd resin used in the present invention may be prepared by using other polyhydric alcohols in addition to pentaerythritol.

[0028] An alkyd resin having a pentaerythritol skeleton in the molecule can be obtained, for example, as a polycondensate of an acid component composed of a fatty acid and a polybasic acid and a polyhydric alcohol containing at least pentaerythritol. Next, a method for preparing such an alkyd resin will be described.

[0029] Fatty acids are obtained by hydrolyzing natural oils and fats such as vegetable oils and animal oils. Since they have one carboxyl group, they can form esters with polyhydric alcohols described below. By introducing such fatty acids into alkyd resins, the transferability of ink compositions using them can be enhanced, or the proportion of biomass-derived components can be increased. From such a viewpoint, it is preferable to use an amount of fatty acid such that the oil length, which is the ratio (mass %) of the mass of the fatty acid portion to the mass of the entire resin, is about 20 to 50 mass %. As such a fatty acid, coconut oil is preferably mentioned. Although various fatty acids can be mentioned, these can be used alone or in combination of two or more.

[0030] Polybasic acids are compounds having a plurality of carboxyl groups and are components for polycondensing with polyhydric alcohols described below to increase the molecular weight. Examples of such polybasic acids include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, trimellitic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexenedicarboxylic acid, 1,4-cyclohexenedicarboxylic acid, hexahydrophthalic anhydride, 5-sodium sulfoisophthalic acid, fumaric acid, benzoic acid, tert-butylbenzoic acid, tetrahydrophthalic anhydride, maleic anhydride, succinic acid, succinic anhydride, fumaric acid, sebacic acid, azelaic acid, tetrabromophthalic anhydride, methyl hymic anhydride, tetrachlorophthalic anhydride, hexahydrophthalic anhydride, pyromellitic anhydride, trimellitic anhydride, methylcyclohexenedicarboxylic anhydride, and the like. Among these, phthalic acid or phthalic anhydride is preferably mentioned. These polybasic acids can be used alone or in combination of two or more.

[0031] Polyhydric alcohols form esters with the above acid components and increase the molecular weight of these components. As polyhydric alcohols, those that have been used for the synthesis of alkyd resins so far can be used without limitation, and compounds having two or more hydroxyl groups are mentioned.

[0032] Examples of such compounds include, in addition to the above-mentioned pentaerythritol, ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, 1,3-butanediol, neopentyl glycol, spiroglycol, dioxane glycol, adamantanediol, 3-methyl-1,5-pentanediol, methyloctanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 2-methyl-1,3-propanediol, hexamethylene glycol, octylene glycol, 9-nonanediol, 2,4-diethyl-1,5-pentanediol, ethylene oxide-modified compounds of bifunctional phenols such as bisphenol A, propylene oxide-modified compounds of bifunctional phenols such as bisphenol A, ethylene oxide, propylene oxide copolymer-modified compounds of bisphenol A, copolymer polyether polyols of ethylene oxide and propylene oxide, polycarbonate diol, adamantanediol, polyether diol, polyester diol, polycaprolactone diol, etc. These can be used alone or in combination of two or more.

[0033] To prepare an alkyd resin, a method can be cited in which a small amount of a solvent such as xylene is added to a reaction kettle charged with these acid components and polyhydric alcohol, and heating is carried out while flowing an inert gas such as nitrogen gas, and azeotroping with condensed water to remove water while carrying out polycondensation. Further, taking the polycondensation reaction of these acid components and polyhydric alcohol as the first stage, and as the second stage, by carrying out polycondensation using a polybasic acid having three or more functional groups such as trimellitic acid, an alkyd resin that gives a highly crosslinked and tough cured film can also be obtained. The reaction temperature can be about 170 to 250 °C, and the reaction time can be about 5 to 25 hours, but it is not particularly limited. The end of the reaction can be determined by monitoring the acid value of the reaction mixture according to the passage of the reaction time. That is, the reaction can be terminated when the decrease in the acid value of the reaction mixture accompanying polycondensation stops. The polycondensation reaction can be carried out in a shorter time by distilling out the water generated by polycondensation outside the system or using a reaction catalyst. Examples of the reaction catalyst include tetrabutyl zirconate, monobutyltin oxide (monobutyltin oxide), zirconium naphthenate, tetrabutyl titanate, etc.

[0034] The mass average molecular weight of the alkyd resin can preferably be less than 10,000, more preferably 8,500 or less, and even more preferably 7,000 or less. As described above, in the present invention, by using neutral carbon black, the impact resistance after retort treatment of the ink film formed on the metal can be improved. However, by using such a relatively low molecular weight alkyd resin, this impact resistance can be further improved, which is preferable.

[0035] The weight-average molecular weight of the resin in the present invention can be measured by gel permeation chromatography (GPC). As an example, Waters Acquity APC (Waters) is used as the GPC apparatus, and ACQUITY APC XT 45 1.7μm 4.6×150mm, ACQUITY APC XT 200 2.5μm 4.6×75mm, and ACQUITY APC XT 900 2.5μm 4.6×75mm (Waters) are used as columns respectively. Chromatography is performed under the conditions of using tetrahydrofuran as the mobile phase, a column temperature of 40°C, a flow rate of 0.8 milliliters per minute, an RI detector, a sample injection concentration of 10 milligrams / 5 milliliters, and an injection volume of 10 microliters, and the value obtained as the weight-average molecular weight in terms of polystyrene can be cited.

[0036] The content of the alkyd resin in the ink composition is preferably 10 to 40% by mass, more preferably 20 to 40% by mass, based on the total composition.

[0037] The rosin-modified resin is a resin prepared using rosin as one of the raw materials. Rosin contains resin acids such as abietic acid, palustric acid, isopimaric acid, and levopimaric acid as a mixture. These resin acids contain hydrophilic and chemically active carboxyl groups, and some of them have conjugated double bonds. Therefore, various rosin-modified resins are prepared by, for example, condensation polymerization by combining polyhydric alcohols and polybasic acids, adding resole, which is a condensate of phenol, to the benzene ring contained in the rosin skeleton, or causing a Diels-Alder reaction with maleic anhydride or maleic acid, which is a dienophile, to add a maleic acid or maleic anhydride skeleton. Such rosin-modified resins are commercially available in various types, and it is also possible to obtain and use them.

[0038] Examples of the rosin-modified resin include rosin ester resin, maleated rosin, fumarated rosin resin, rosin-modified maleic acid resin, rosin-modified fumaric acid resin, rosin-modified phenol resin, rosin-modified alkyd resin, rosin-modified polyester resin, and the like. In the present invention, any rosin-modified resin may be used, but among these, rosin ester resin is preferably used.

[0039] As the rosin-modified resin used in the present invention, it is preferable to use one having a hydroxyl value of 10 mgKOH / g or more. By including such a rosin-modified resin having a high hydroxyl value in the ink composition of the present invention, the transferability of the ink composition during printing can be further improved, and as the polarity of the composition itself increases, the affinity for the highly polar aqueous OP varnish also increases, and the effect of suppressing repelling even when it is wet-on-wet coated is also achieved. The hydroxyl value of the rosin-modified resin is more preferably 15 mgKOH / g or more, and even more preferably 20 mgKOH / g or more. Also, the upper limit of the hydroxyl value of the rosin-modified resin is not particularly limited, but as an example, about 200 mgKOH / g can be mentioned, preferably about 150 mgKOH / g, and more preferably about 100 mgKOH / g.

[0040] Also, although not particularly limited, the acid value of the rosin-modified resin can preferably be 100 mgKOH / g or less. When the acid value of the rosin-modified resin is 100 mgKOH / g or less, it is preferable because it can achieve both suppression of repelling when the aqueous OP varnish is wet-on-wet coated and printing suitability such as suppression of misting and overflowing from the pot. The acid value of the rosin-modified resin can more preferably be 80 mgKOH / g or less, and even more preferably 50 mgKOH / g or less.

[0041] The rosin-modified resin is used in a state where it is dissolved or dispersed by heating together with a solvent described later to form a varnish. The rosin-modified resin may be used as a dissolved varnish that remains dissolved or dispersed in the solvent, or when preparing the varnish, a divalent or higher metal alkoxy compound may be added as a gelling agent to the dissolved varnish obtained by dissolving the resin, and it may be used in a state of being a gelled varnish. Among these, it is preferable to prepare a dissolved varnish from the rosin-modified resin and use it in the preparation of the ink composition, as it can improve the transferability of the ink composition during printing. Also, by preparing a gelled varnish from the rosin-modified resin and using it in the preparation of the ink composition, appropriate viscoelasticity can be imparted to the ink composition, fluidity can be improved and misting can be reduced, and a stronger and tougher cured film can be formed.

[0042] The content of the rosin-modified resin in the ink composition is preferably 5 to 50% by mass, more preferably 5 to 25% by mass, and even more preferably 7 to 20% by mass with respect to the entire composition.

[0043] In addition to the above alkyd resin and rosin-modified resin, the ink composition of the present invention can also be used in combination with resins conventionally used in the preparation of metal printing ink compositions. That is, depending on the required performance such as printing suitability and coating film physical properties, known resins compatible with the above alkyd resin and rosin-modified resin can be used alone or in a mixture of two or more. Examples of such resins include polyester resins, petroleum resins, epoxy resins, ketone resins, amino resins, benzoguanamine resins, and the like.

[0044] [Solvent] As the solvent used in the ink composition of the present invention, those that have been used in the field of inks for metal printing can be listed without particular limitation. Examples of such solvents include aliphatic hydrocarbons, alicyclic hydrocarbons, alkylbenzenes, polyalkylene glycols, etc. having a boiling point range of about 230 to 400 °C. Among these, the ink composition of the present invention has a solubility parameter (sp value) of less than 10.00 (cal / cm 3 ) 1 / 2 and contains at least one selected from the group consisting of compounds represented by the following general formula (1) as essential. Hereinafter, a solvent having a solubility parameter (sp value) of less than 10.00 (cal / cm 3 ) 1 / 2 and at least one selected from the group consisting of compounds represented by the following general formula (1) is also referred to as a specific solvent. The sp value of the specific solvent is preferably less than 9.80 (cal / cm 3 ) 1 / 2 . Further, as the lower limit value of the sp value of the specific solvent, about 8.50 (cal / cm 3 ) 1 / 2 is preferably mentioned, and about 9.00 (cal / cm 3 ) 1 / 2 is more preferably mentioned. Such a specific solvent having such an sp value can also be referred to as a polyalkylene glycol monoalkyl ether having hydrophobic properties. The reason for using such a specific solvent having hydrophobic properties in the present invention is that, instead of alkylbenzene-based solvents and hydrophilic polyalkylene glycol monoalkyl ether-based solvents that have been widely used in the field of metal printing ink compositions, by using a hydrophobic polyalkylene glycol monoalkyl ether (i.e., a specific solvent), the occurrence of misting during printing can be significantly reduced, according to the findings of the present inventors.

[0045]

Chemical formula

[0046] In the general formula (1) above, each A is independently an alkylene group having 2 to 4 carbon atoms which may have a branch. Examples of such an alkylene group include an ethylene group [-(CH 2 ) 2 -], a propylene group [-CH 2 (CH 3 )-CH 2 -, or -CH 2 CH 2 (CH 3 )-], a trimethylene group [-(CH 2 ) 3 -], an isopropylidene group [-C(CH 3 ) 2 -], etc. Among these, a propylene group is preferably mentioned. In this case, the divalent group represented by AO in the general formula (1) is an oxypropylene group.

[0047] In the general formula (1) above, R is an alkyl group having 1 to 13 carbon atoms which may have a branch and / or a ring structure. Note that this alkyl group may be an alicyclic group as well as an aliphatic group. Examples of such an alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a hexyl group, a 2-ethylhexyl group, an octyl group, a decyl group, a cyclohexyl group, etc.

[0048] In the general formula (1) above, n is an integer of 2 to 8. When n is 2 or more, it is preferable because a sufficient boiling point of a specific solvent can be ensured to impart stability to the ink composition on the printing machine. When n is 8 or less, a preferable viscosity can be achieved as the solvent of the ink composition.

[0049] Examples of the compound represented by the general formula (1) above include dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monooctyl ether, dipropylene glycol tridecyl ether, tripropylene glycol monobutyl ether, tripropylene glycol monodecyl ether, tetrapropylene glycol monohexyl ether, pentapropylene glycol monobutyl ether, hexapropylene glycol monomethyl ether, and the like.

[0050] In addition, as the sp value in the present invention, the one calculated by the Fedros method is used (see the literature: R.F. Fedros, Polym. Eng. Sci., 14(2) 147 (1974)).

[0051] The content of the solvent in the ink composition of the present invention is preferably 10 to 50% by mass, more preferably 20 to 45% by mass, based on the total composition. Among the solvents, the content of the specific solvent is preferably 15 to 40% by mass based on the total composition, and it is preferable that all of the solvents in the composition are the specific solvent.

[0052] The ink composition of the present invention preferably contains alkanolamine in addition to the above components. By containing alkanolamine in the ink composition of the present invention, it is possible to improve both the reduction of misting during printing and the impact resistance after retort treatment in the printed film.

[0053] Examples of the alkanolamine include monoethanolamine, diethanolamine, triethanolamine, ethylmonoethanolamine, n-butylmonoethanolamine, dimethylethanolamine, diethylethanolamine, ethyldiethanolamine, n-butyldiethanolamine, di-n-butylethanolamine, triisopropanolamine, and the like. Among these, triethanolamine is preferably mentioned.

[0054] The content of alkanolamine in the ink composition of the present invention is preferably 0.1 to 3% by mass, more preferably 0.1 to 1% by mass, based on the entire composition.

[0055] In the ink composition of the present invention, as other components, known curing agents, pigment dispersants, waxes, extender pigments such as silica particles, calcium carbonate, bentonite clay, kaolin, talc, and stabilizers can be added as necessary.

[0056] As the curing agent, for example, amino resins such as melamine resin and benzoguanamine resin can be used.

[0057] Silica particles are commercially available as powders of SiO 2 and it is possible to easily obtain those that are not particularly surface-treated or are hydrophilic ones that have been hydrophilized, or hydrophobic ones that have been hydrophobized. Among these silica particles, in the ink composition of the present invention, hydrophobic silica particles are preferably used. By using hydrophobic silica particles, the transferability of the ink composition during printing can be made better, and the fluidity of the ink composition can be increased, which is preferable. The content of silica particles in the ink composition is preferably 0.5 to 15% by mass, more preferably 1 to 5% by mass.

[0058] The ink composition of the present invention can be prepared by mixing the above-mentioned components by a conventional method using a roll mill, ball mill, bead mill, etc. The viscosity of the ink composition can be exemplified by a value of 10 to 70 Pa·s at 25°C measured by a rheometer, but is not particularly limited.

[0059] The metal for metal printing in the ink composition of the present invention is not particularly limited, and examples include galvanized or tinned iron plates, aluminum plates, or metal cans made of these metal materials.

Examples

[0060] Hereinafter, the ink composition of the present invention will be described in more detail by showing examples, but the present invention is not limited to the following examples at all.

[0061] [Preparation of Alkyd Resin Varnish 1] 5.98 parts by mass of neopentyl glycol, 8.53 parts by mass of pentaerythritol, 11.00 parts by mass of coconut oil fatty acid, 7.30 parts by mass of isophthalic acid, and 6.50 parts by mass of phthalic anhydride were reacted at 220 ° C. in a nitrogen atmosphere until the acid value of the mixture reached 7 mgKOH / g to perform the first-stage esterification. Then, 0.70 part by mass of trimellitic anhydride was added and heated at 165 ° C. for 30 minutes in a nitrogen atmosphere to perform the second-stage esterification. These esterification reactions were carried out according to a conventional method to obtain an alkyd resin 1 having a mass average molecular weight of 4,376 and a number average molecular weight of 1,995. To this alkyd resin 1, 15.0 parts by mass of tripropylene glycol monobutyl ether was added to obtain alkyd resin varnish 1. The sp value of this tripropylene glycol monobutyl ether is 9.73 (cal / cm 3 ) 1 / 2 and it corresponds to the specific solvent in the present invention.

[0062] [Preparation of Alkyd Resin Varnish 2] 5.00 parts by mass of neopentyl glycol, 9.18 parts by mass of pentaerythritol, 11.00 parts by mass of coconut oil fatty acid, 7.30 parts by mass of isophthalic acid, and 6.50 parts by mass of phthalic anhydride were reacted at 220 ° C. in a nitrogen atmosphere until the acid value of the mixture reached 7 mgKOH / g to perform the first-stage esterification. Then, 0.70 part by mass of trimellitic anhydride was added and heated at 165 ° C. for 30 minutes in a nitrogen atmosphere to perform the second-stage esterification. These esterification reactions were carried out according to a conventional method to obtain an alkyd resin 2 having a mass average molecular weight of 4,764 and a number average molecular weight of 2,348. To this alkyd resin 2, 10.0 parts by mass of tripropylene glycol monobutyl ether was added to obtain alkyd resin varnish 2. The sp value of this tripropylene glycol monobutyl ether is 9.73 (cal / cm 3 ) 1 / 2 and it corresponds to the specific solvent in the present invention.

[0063] [Preparation of Alkyd Resin Varnish 3] 5.00 parts by mass of neopentyl glycol, 10.80 parts by mass of trimethylolpropane, 11.00 parts by mass of coconut oil fatty acid, 7.30 parts by mass of isophthalic acid and 6.50 parts by mass of phthalic anhydride were reacted at 220°C under a nitrogen atmosphere until the acid value of the mixture reached 7 mgKOH / g to perform the first-stage esterification. Then, 0.70 parts by mass of trimellitic anhydride was added and heated at 165°C for 30 minutes under a nitrogen atmosphere to perform the second-stage esterification. These esterification reactions were carried out according to a conventional method to obtain an alkyd resin 3 with a mass average molecular weight of 2,785 and a number average molecular weight of 1,639. To this alkyd resin 3, 10.0 parts by mass of tripropylene glycol monobutyl ether was added to obtain alkyd resin varnish 3. The sp value of this tripropylene glycol monobutyl ether is 9.73 (cal / cm 3 ) 1 / 2 and it corresponds to the specific solvent in the present invention.

[0064] [Preparation of Alkyd Resin Varnish 4] 5.98 parts by mass of neopentyl glycol, 8.53 parts by mass of pentaerythritol, 10.10 parts by mass of coconut oil fatty acid, 11.95 parts by mass of isophthalic acid and 2.48 parts by mass of terephthalic acid were reacted at 220°C under a nitrogen atmosphere until the acid value of the mixture reached 7 mgKOH / g to perform the first-stage esterification. Then, 0.70 parts by mass of trimellitic anhydride was added and heated at 165°C for 30 minutes under a nitrogen atmosphere to perform the second-stage esterification. These esterification reactions were carried out according to a conventional method to obtain an alkyd resin 4 with a mass average molecular weight of 6,049 and a number average molecular weight of 2,591. To this alkyd resin 4, 21.8 parts by mass of tripropylene glycol monobutyl ether was added to obtain alkyd resin varnish 4. The sp value of this tripropylene glycol monobutyl ether is 9.73 (cal / cm 3 ) 1 / 2 and it corresponds to the specific solvent in the present invention.

[0065] [Preparation of Alkyd Resin Varnish 5] To the alkyd resin 2 obtained in the procedure for preparing the above alkyd resin varnish 2, triethylene glycol monobutyl ether was added instead of tripropylene glycol monobutyl ether to obtain alkyd resin varnish 5. The sp value of this triethylene glycol monobutyl ether is 10.32 (cal / cm 3 ) 1 / 2 and it does not correspond to the specific solvent in the present invention.

[0066] [Preparation of alkyd resin varnish 6] To the alkyd resin 2 obtained in the procedure for preparing the above alkyd resin varnish 2, pentapropylene glycol monobutyl ether was added instead of tripropylene glycol monobutyl ether to obtain alkyd resin varnish 6. The sp value of pentapropylene glycol monobutyl ether is 9.42 (cal / cm 3 ) 1 / 2 and it corresponds to the specific solvent in the present invention.

[0067] [Preparation of alkyd resin varnish 7] To the alkyd resin 2 obtained in the procedure for preparing the above alkyd resin varnish 2, tetrapropylene glycol mono-2-ethylhexyl ether was added instead of tripropylene glycol monobutyl ether to obtain alkyd resin varnish 7. The sp value of tetrapropylene glycol mono-2-ethylhexyl ether is 9.32 (cal / cm 3 ) 1 / 2 and it corresponds to the specific solvent in the present invention.

[0068] [Preparation of rosin-modified resin varnish 1] 63.2 parts by mass of a rosin ester resin (hydroxyl value 20 to 30 mgKOH / g, acid value < 10 mgKOH / g, mass average molecular weight 632, number average molecular weight 565) and 35.9 parts by mass of tripropylene glycol monobutyl ether were heated at 130°C for 1 hour to dissolve them, and rosin-modified resin varnish 1 was obtained. The sp value of this tripropylene glycol monobutyl ether is 9.73 (cal / cm 3 )1 / 2 It is applicable to the specific solvent in the present invention.

[0069] [Preparation of Rosin-Modified Resin Varnish 2] Rosin-modified resin varnish 2 was obtained in the same procedure as the preparation of the above rosin-modified resin varnish 1, except that triethylene glycol monobutyl ether was used instead of tripropylene glycol monobutyl ether. The sp value of this triethylene glycol monobutyl ether is 10.32 (cal / cm 3 ) 1 / 2 It does not correspond to the specific solvent in the present invention.

[0070] [Preparation of Rosin-Modified Resin Varnish 3] Rosin-modified resin varnish 3 was obtained in the same procedure as the preparation of the above rosin-modified resin varnish 1, except that pentapropylene glycol monobutyl ether was used instead of tripropylene glycol monobutyl ether. The sp value of this pentapropylene glycol monobutyl ether is 9.42 (cal / cm 3 ) 1 / 2 It is applicable to the specific solvent in the present invention.

[0071] [Preparation of Rosin-Modified Resin Varnish 4] Rosin-modified resin varnish 4 was obtained in the same procedure as the preparation of the above rosin-modified resin varnish 1, except that tetrapropylene glycol mono-2-ethylhexyl ether was used instead of tripropylene glycol monobutyl ether. The sp value of this tetrapropylene glycol mono-2-ethylhexyl ether is 9.32 (cal / cm 3 ) 1 / 2 It is applicable to the specific solvent in the present invention.

[0072] [Examples 1 to 12, Comparative Examples 1 to 3] The respective components were mixed according to the formulations in Tables 1 to 3, and the obtained mixtures were kneaded using a three-roll mill to prepare the ink compositions of Examples 1 to 12 and Comparative Examples 1 to 3. In Tables 1 to 3, "Neutral CB1" is HIBLACK 200L manufactured by Orion Engineered Carbons (neutral carbon black, primary particle size 28 nm, DBP oil absorption 62 ml / 100 g, pH 8.0), "Neutral CB2" is ELFTEX 415 manufactured by Cabot (neutral carbon black, primary particle size 25 nm, DBP oil absorption 55 ml / 100 g, pH 6.0 or more and 8.0 or less), "Neutral CB3" is Regal 250R manufactured by Cabot (neutral carbon black, primary particle size 34 nm, DBP oil absorption 48 ml / 100 g, pH 6.0 or more and 8.0 or less), "Neutral CB4" is Regal 350R manufactured by Cabot (neutral carbon black, primary particle size 48 nm, DBP oil absorption 46 ml / 100 g, pH 6.0 or more and 8.0 or less), "Acidic CB1" is Mitsubishi Carbon Black MA7 manufactured by Mitsubishi Chemical Corporation (acidic carbon black, primary particle size 24 nm, DBP oil absorption 66 ml / 100 g, pH 3.0), and "Acidic CB2" is Mogul E manufactured by Cabot (acidic carbon black, primary particle size 48 nm, DBP oil absorption 49 ml / 100 g, pH 2.5). Also, in Tables 1 to 3, "Specific Solvent 1" is tripropylene glycol monobutyl ether (sp value 9.73 (cal / cm 3 ) 1 / 2 ), "Specific Solvent 2" is pentapropylene glycol monobutyl ether (sp value 9.42 (cal / cm 3 ) 1 / 2 ), "Specific Solvent 3" is tetrapropylene glycol mono-2-ethylhexyl ether (sp value is 9.32 (cal / cm 3 ) 1 / 2 ), "Non-Specific Solvent" is triethylene glycol monobutyl ether (sp value 10.32 (cal / cm 3 ) 1 / 2 ), and "Silica" is surface-hydrophobically treated silica particles (manufactured by Nippon Aerosil Co., Ltd., product name Aerosil R972). The numerical values of each blending amount in Tables 1 to 3 are all in parts by mass.

[0073] [Misting Amount Evaluation] For each of the ink compositions of the examples and comparative examples, 2.6 cc of the ink composition was taken, applied to the rotating roller of the inkometer, and leveled. Then, it was rotated at 1200 rpm for 3 minutes. During this time, a white paper was placed under the roller, and the amount of ink composition adhering to the surface due to misting was compared. The measurement was performed with the roller maintained at 40°C. The mass change of the white paper before and after the measurement was determined and taken as the misting amount (mg). The larger the mass change of the white paper before and after the measurement, the greater the amount of ink composition scattered. Therefore, the smaller this value, the better the result. Based on the calculated misting amount (mg), the evaluation was carried out according to the following criteria. The evaluation results are shown in the "Misting" column of Tables 1 to 3. ○: The misting amount was less than 5 mg △: The misting amount was 5 mg or more and less than 10 mg ×: The misting amount was 10 mg or more

[0074] [Impact Resistance Evaluation after Retort Treatment] For each of the examples and comparative examples, 0.2 cc of the ink composition was applied using a RI color development machine onto an aluminum substrate with a thickness of 50 μm to obtain a color-developed product. Then, using a No. 0.4 bar coater (Mayer bar), overprint varnish for retort (manufactured by AkzoNobel) was applied to the color-developed surface of the color-developed product, and it was held in an oven at 240°C for 2 minutes to obtain a retort sample. Then, the retort sample was subjected to retort treatment using an autoclave (high-pressure steam sterilizer, HG-50 manufactured by Hirayama Seisakusho Co., Ltd.) under the conditions of 125°C for 30 minutes to obtain a retorted product. The obtained retorted product was subjected to impact on 4 locations from the opposite side of the color-developed surface using a DuPont impact tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name H-50) under the conditions of a punch core diameter: 1 / 4Φ (6.35 mm), weight weight: 300 g, and weight drop height: 50 mm, and the degree of peeling of the coating film on the color-developed surface side was evaluated according to the following criteria. The results are shown in the "Impact Resistance after Retort" column of Tables 1 to 3. ○: For all 4 locations, the coating film at the location in contact with the punch core did not peel off ×: For at least one of the four locations, at least a part of the coating film at the location in contact with the firing pin has peeled off, and the aluminum base material is exposed.

[0075]

Table 1

[0076]

Table 2

[0077]

Table 3

[0078] As is clear from Tables 1 to 3, it can be understood that by combining neutral carbon black with a specific solvent that satisfies a predetermined solubility parameter to form an ink composition for metal printing, the misting suitability and the impact resistance after retort become good.

Claims

1. A metal printing ink composition comprising carbon black, a resin and a solvent, The carbon black includes neutral carbon black, The solvent has a solubility parameter (sp value) of 10.00 (cal / cm ３ ) １／２ and containing at least one compound selected from the group consisting of compounds represented by the following general formula (1): 【Chemistry 1】 (In the above general formula (1), each A is independently an alkylene group having 2 to 4 carbon atoms which may have a branch, R is an alkyl group having 1 to 13 carbon atoms which may have a branched and / or cyclic structure, and n is an integer of 2 to 8.)

2. 2. The ink composition for metal printing according to claim 1, wherein said resin is an alkyd resin.

3. 3. The ink composition for metal printing according to claim 2, wherein the alkyd resin has a mass average molecular weight of less than 10,000.

4. 3. The ink composition for metal printing according to claim 2, wherein the alkyd resin has a pentaerythritol skeleton.

5. 2. The ink composition for metal printing according to claim 1, wherein the divalent group represented by AO in formula (1) is an oxypropylene group.

6. 2. The ink composition for metal printing according to claim 1, further comprising an alkanolamine.

7. 2. The ink composition for metal printing according to claim 1, further comprising a rosin-modified resin.

Images