JP2016148006A - Coating composition for metal cap and metal cap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition for a metal cap which forms a coating film excellent in coating film appearance, processability, cap openability, and adhesion to a liner.SOLUTION: The coating composition for a metal cap contains a hydroxyl group-containing polyester resin and/or a bisphenol type epoxy resin (A), a curing agent (B), a fatty acid ester (C), an antioxidant (D), and an oxidized polyolefin (E). The coating composition for a metal cap contains 0.1-10 pts.mass of the fatty acid ester (C), 0.05-10 pts.mass of the antioxidant (D), and 1-15 pts.mass of the oxidized polyolefin (E) based on 100 pts.mass of the total solid content of the hydroxyl group-containing polyester resin and/or the bisphenol type epoxy resin (A) and the curing agent (B).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coating composition for a metal cap capable of forming a coating film having good coating film appearance, processability, cap opening ability and liner adhesion, and a metal obtained by coating the coating composition for a metal cap. Regarding the cap.

  Metal caps used for glass bottles and metal cans are widely used in containers such as soft drinks on the market. Among such metal caps, a pilfer-proof cap (hereinafter sometimes referred to as a “PP cap”) as shown in FIG. 1 has a disk-shaped top surface portion (1) and a cylindrical side trunk hanging from the outer periphery. It consists of a part (2), and the annular skirt-like skirt part (3) is provided in the lower end part.

  In order to produce such a PP cap, the metal cap coating composition (4) is applied to a metal plate, dried by heating to form a coating-coated metal plate, and then molded into a cap shape. In order to enhance the hermeticity of an object, a method in which a polyethylene sheet (hereinafter sometimes referred to as liner material (5)) is pressure-bonded to the back of the cap is generally used.

  The coating-coated metal sheet is required to have workability to withstand drawing and ironing, while the PP cap top surface has good adhesion to the liner material (5). The side portion is required to have good cap opening performance.

  In addition, if the coating-coated metal sheet is left for more than one week before the liner material (5) is pressure-bonded, the adhesion between the PP cap top surface portion and the liner material (5) may decrease. It was.

  For example, Patent Document 1 discloses a resin composition (a) composed of a hydroxyl group-containing resin and an amino resin, a resin composition (b) composed of a carboxyl group-containing resin and an epoxy group-containing resin, and a resin composition containing a vinyl resin. A coating composition for a metal cap containing 1 to 10 parts by mass of a fatty acid ester having a freezing point of 10 ° C. or less based on 100 parts by mass of the resin solid content of the resin composition (A) selected from (c) is disclosed.

  In Patent Document 2, 1 to 100 parts by mass of oxidized polyolefin (C) is added to 100 parts by mass of the total solid content of hydroxyl group-containing polyester resin (A) 70 to 95 parts by mass and melamine resin (B) 5 to 30 parts by mass. A coating composition for a metal cap containing 15 parts by mass and 0.5 to 10 parts by mass of a fatty acid ester (D) is disclosed.

  In addition, Patent Document 3 discloses that an ethylene-unsaturated carboxylic acid copolymer is used for a total solid content of 100 parts by mass of 60 to 95 parts by mass of the epoxy resin (A) and 5 to 40 parts by mass of the phenol resin (B). A coating composition for metal caps containing 1 to 100 parts by mass of solid resin (C) in solid content is disclosed.

  However, the coating compositions for metal caps described in Patent Documents 1 to 3 are insufficient in any one of coating film appearance, processability, cap opening property, and liner adhesion, and in particular, a coating-coated metal plate However, if it is left for a long time before the liner material is pressure-bonded, the adhesion between the PP cap top surface portion and the liner material may be lowered. From such a background, there has been a demand for a coating composition for a metal cap that satisfies all of the appearance of the coating film, processability, cap opening ability, and liner adhesion.

JP 2003-253195 A JP 2007-112889 A JP 2008-156595 A

  The problem to be solved by the invention is to find a coating composition for a metal cap capable of forming a coating film having good coating film appearance, processability, cap opening property and liner adhesion, and to provide a metal cap having excellent performance. Is to provide. In particular, a coating composition for a metal cap that can form a coating film with good liner adhesion even when the coating film-coated metal sheet is left standing for a long time before the liner material is pressure-bonded. That is.

  As a result of intensive studies to solve the above problems, the present inventors have found that a hydroxyl group-containing polyester resin and / or a bisphenol type epoxy resin (A), a curing agent (B), a fatty acid ester (C), an antioxidant (D) and The present inventors have found that a metal cap coating composition containing an oxidized polyolefin (E) is extremely useful for solving the above problems, and has completed the present invention.

That is, the present invention
1. A coating composition containing a hydroxyl group-containing polyester resin and / or a bisphenol type epoxy resin (A), a curing agent (B), a fatty acid ester (C), an antioxidant (D) and an oxidized polyolefin (E), 0.1 to 10 parts by mass of fatty acid ester (C) and antioxidant (D) with respect to 100 parts by mass in total of the solid content of the polyester resin and / or bisphenol type epoxy resin (A) and curing agent (B) ) 0.05 to 10 parts by mass and the oxidized polyolefin (E) 1 to 15 parts by mass, a coating composition for metal caps,
2. 1 item | term containing 1-15 mass parts of novolak-type epoxy resins (F) with respect to a solid content total of 100 mass parts of a hydroxyl-containing polyester resin and / or bisphenol-type epoxy resin (A) and a hardening | curing agent (B). The coating composition for a metal cap according to the description,
3. The coating composition for metal cap according to 1 or 2, wherein the fatty acid ester (C) is liquid at room temperature,
4). 4. The metal cap coating composition according to any one of items 1 to 3, wherein the fatty acid ester (C) has an iodine value of 10 to 110.

5. The coating composition for a metal cap according to any one of 1 to 4, which contains at least two kinds of antioxidants (D),
The present invention relates to a metal cap formed by coating the metal cap coating composition according to any one of 6.1 to 5.

  The metal cap coating composition of the present invention can provide a metal cap having a coating film excellent in coating film appearance, processability, cap opening ability, and liner adhesion. For example, even if the coating-coated metal plate is left for a long period of time before the liner material is pressure-bonded, the adhesion between the PP cap top surface portion and the liner material does not decrease.

It is a model figure of a pilfer proof cap. It is a model figure which crimps | bonds a liner material. It is a model figure of the T peel test which is a substitute test of liner adhesion.

  The metal cap coating composition of the present invention comprises a hydroxyl group-containing polyester resin and / or bisphenol type epoxy resin (A), a curing agent (B), a fatty acid ester (C), an antioxidant (D), and an oxidized polyolefin (E). It is the coating composition containing this. Details will be described below.

Hydroxyl-containing polyester resin and / or bisphenol type epoxy resin (A)
The hydroxyl group-containing polyester resin can be usually produced by an esterification reaction or a transesterification reaction between the polybasic acid component (a1) and the polyhydric alcohol component (a2).

  As said polybasic acid component (a1), an alicyclic polybasic acid component, an aliphatic polybasic acid component, an aromatic polybasic acid component, etc. can be used, for example.

  As the alicyclic polybasic acid component, generally, a compound having one or more alicyclic structures (mainly 4 to 6-membered rings) and two or more carboxyl groups in one molecule, an acid anhydride of the compound And an esterified product of the compound. Examples of the alicyclic polybasic acid component include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 3- Alicyclic polycarboxylic acids such as methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid An anhydride of these alicyclic polyvalent carboxylic acids; a lower alkyl esterified product of these alicyclic polyvalent carboxylic acids. An alicyclic polybasic acid component can be used individually or in combination of 2 or more types.

  As the alicyclic polybasic acid component, in particular, 1,2-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic anhydride, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene- 1,2-dicarboxylic acid and 4-cyclohexene-1,2-dicarboxylic anhydride can be preferably used. Among the above, 1,2-cyclohexanedicarboxylic acid and 1,2-cyclohexanedicarboxylic anhydride can be particularly preferably used from the viewpoint of hydrolysis resistance.

  The aliphatic polybasic acid component is generally an aliphatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aliphatic compound, and an esterified product of the aliphatic compound, for example, Aliphatic polycarboxylic acids such as acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, octadecanedioic acid, citric acid; An anhydride of a polyvalent carboxylic acid; a lower alkyl esterified product of these aliphatic polyvalent carboxylic acids. An aliphatic polybasic acid component can be used individually or in combination of 2 or more types.

As the aliphatic polybasic acid component, it is preferable to use a dicarboxylic acid having an alkylene chain having 4 to 18 carbon atoms. Examples of the dicarboxylic acid having an alkylene chain having 4 to 18 carbon atoms include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, and octadecanedioic acid. Among them, adipic acid can be preferably used.
The aromatic polybasic acid component is generally an aromatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aromatic compound and a lower alkyl esterified product of the aromatic compound, For example, aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, trimellitic acid, pyromellitic acid; anhydrides of these aromatic polycarboxylic acids And lower alkyl esterified products of these aromatic polycarboxylic acids. An aromatic polybasic acid component can be used individually or in combination of 2 or more types.

  As the polyhydric alcohol component, a polyhydric alcohol having two or more hydroxyl groups in one molecule can be preferably used. Examples of the polyhydric alcohol include alicyclic diols, aliphatic diols, aromatic diols, and trihydric or higher polyhydric alcohols.

  The alicyclic diol is generally a compound having one or more alicyclic structures (mainly 4- to 6-membered rings) and two hydroxyl groups in one molecule. Examples of the alicyclic diol include dihydric alcohols such as 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, hydrogenated bisphenol A, and hydrogenated bisphenol F; ε-caprolactone and the like in these dihydric alcohols. Examples include polylactone diol to which a lactone compound is added, and these can be used alone or in combination of two or more.

  The aliphatic diol is generally an aliphatic compound having two hydroxyl groups in one molecule. Examples of the aliphatic diol include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3 -Butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1,5-pentanediol 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3 -Pentanediol, 1,6-hexanediol, 1, -Hexanediol, 1,4-hexanediol, 2,5-hexanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, neopentyl glycol; polyethylene glycol, polypropylene glycol and poly Examples include polyether diol compounds such as butylene glycol, and these can be used alone or in combination of two or more.

  The aromatic diol is generally an aromatic compound having two hydroxyl groups in one molecule. Examples of the aromatic diol include ester diol compounds such as bis (hydroxyethyl) terephthalate; alkylene oxide adducts of bisphenol A and the like, and these can be used alone or in combination of two or more.

  Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, sorbitol, and mannitol. A trilactone or higher alcohol; a polylactone polyol compound obtained by adding a lactone compound such as ε-caprolactone to the trihydric or higher alcohol; tris (2-hydroxyethyl) isocyanurate, tris (2-hydroxypropyl) isocyanurate, And tris (hydroxyalkyl) isocyanurate such as tris (2-hydroxybutyl) isocyanurate. Of these, trimethylolpropane is particularly preferable.

  The production of the hydroxyl group-containing polyester resin is not particularly limited, and can be performed according to a usual method. For example, the acid component having the polybasic acid component (a1) as an essential component and the polyhydric alcohol component (a2) are reacted in a nitrogen stream at 150 to 250 ° C. for 5 to 10 hours to perform esterification or transesterification. It can manufacture by performing reaction. In the esterification reaction or transesterification reaction, the acid component and alcohol component may be added at once, or may be added in several portions.

  The hydroxyl value of the hydroxyl group-containing polyester resin is 1 to 100 mgKOH / g, preferably 3 to 50 mgKOH / g, and the acid value is 100 mgKOH / g or less, preferably 10 to 60 mgKOH / g, from the viewpoint of workability. .

  Moreover, after synthesize | combining a carboxyl group-containing polyester resin first, you may esterify some carboxyl groups in this carboxyl group-containing polyester resin using the said polyhydric alcohol component. Furthermore, after first synthesizing the hydroxyl group-containing polyester resin, the acid anhydride may be reacted to half-esterify the hydroxyl group-containing polyester resin.

In the esterification or transesterification reaction, a catalyst may be used to promote the reaction. As the catalyst, known catalysts such as dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, and tetraisopropyl titanate can be used.
Further, the hydroxyl group-containing polyester resin can be modified with a fatty acid, an oil, a fat, a monoepoxy compound, a monoalcohol compound, a polyisocyanate compound or the like during the preparation of the resin, or after the esterification reaction or the transesterification reaction.

Examples of the fatty acid include coconut oil fatty acid, cottonseed oil fatty acid, hemp seed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, castor oil fatty acid, dehydrated castor Examples include fatty acids such as oil fatty acids and safflower oil fatty acids; lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and the like.
Examples of the fat include coconut oil, cottonseed oil, hemp seed oil, rice bran oil, fish oil, tall oil, soybean oil, linseed oil, tung oil, rapeseed oil, castor oil, dehydrated castor oil, safflower oil and the like.

Examples of the polyisocyanate compound used for the modification include aliphatic diisocyanate compounds such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, methylcyclohexane. -Aliphatic diisocyanate compounds such as 2,6-diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1,3- (isocyanatomethyl) cyclohexane; aromatics such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate Diisocyanate compounds; organic poly- such as tri- or higher polyisocyanates such as lysine triisocyanate Isocyanate itself, or an adduct of each of these organic polyisocyanates with polyhydric alcohol, low molecular weight polyester resin or water, or a cyclized polymer of each of the above organic diisocyanates (for example, isocyanurate), biuret type addition And the like. These can be used alone or in combination of two or more.
The weight average molecular weight of the hydroxyl group-containing polyester resin is preferably from 2,000 to 30,000, particularly preferably from 3,000 to 25,000, from the viewpoints of coating film hardness, workability, and finish of the resulting coating film. It is.

  In addition, in this specification, a weight average molecular weight or a number average molecular weight is the value which converted the weight average molecular weight or the number average molecular weight measured using the gel permeation chromatograph (GPC) on the basis of the molecular weight of a standard polystyrene. . Specifically, “HLC8120GPC” (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph, and “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL” are used as columns. And “TSKgel G-2000HXL” (trade names, all manufactured by Tosoh Corporation), and can be measured under the conditions of mobile phase tetrahydrofuran, measurement temperature 40 ° C., flow rate 1 mL / min, and detector RI. .

Bisphenol-type epoxy resin Specific examples of the bisphenol-type epoxy resin include bisphenol-type epoxy resins and modified epoxy resins obtained by reacting the epoxy groups or hydroxyl groups of the bisphenol-type epoxy resins with various modifiers. The bisphenol type epoxy resin has a number average molecular weight of 900 to 60,000, preferably 2,000 to 20,000 for coating film appearance and processability.

  As the bisphenol type epoxy resin, for example, epichlorohydrin and bisphenol may be condensed to a high molecular weight in the presence of a catalyst such as an alkali catalyst, if necessary, epichlorohydrin and bisphenol, if necessary. Examples thereof include resins obtained by condensation in the presence of a catalyst such as an alkali catalyst to form a low molecular weight epoxy resin and a polyaddition reaction of the low molecular weight epoxy resin and bisphenol.

  Examples of the bisphenol include bis (4-hydroxyphenyl) methane [bisphenol F], 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane [bisphenol A], 2,2-bis (4-hydroxyphenyl) butane [bisphenol B], 2,2-bis (4-hydroxycyclohexyl) propane [hydrogenated bisphenol A], bis (4-hydroxyphenyl) -1,1-isobutane, Bis (4-hydroxy-tert-butyl-phenyl) -2,2-propane, p- (4-hydroxyphenyl) phenol, oxybis (4-hydroxyphenyl), sulfonylbis (4-hydroxyphenyl), 4,4 ′ -Dihydroxybenzophenone, bis (2-hydroxynaphthyl) me Mention may be made of the emissions and the like. The above bisphenols can be used alone or as a mixture of two or more.

  Examples of commercially available products of the bisphenol type epoxy resin include jER828EL, jER1001, jER1004, jER1007, jER1009, jER1010 (above, manufactured by Mitsubishi Chemical Corporation, trade name), AER6097, AER6099 (above, made by Asahi Kasei Chemicals Corporation, trade name). , Epomic R-309 (trade name, manufactured by Mitsui Chemicals) and the like.

  Examples of the modified epoxy resin include an epoxy ester resin obtained by reacting, for example, a dry oil fatty acid with the bisphenol type epoxy resin, and a polymerizable resin containing acrylic acid or methacrylic acid, for example, with the bisphenol type epoxy resin. Epoxy acrylate resin reacted with saturated monomer component, epoxy group of epoxy resin selected from urethane modified epoxy resin reacted with isocyanate compound, bisphenol type epoxy resin and various modified epoxy resins, for example, with bisphenol type epoxy resin And an amine-modified epoxy resin in which an amino group or a quaternary ammonium salt is introduced by reacting with an amine compound.

Curing agent (B)
The curing agent (B) can be used without particular limitation as long as it can be cured by heating and reacting with the hydroxyl group-containing polyester resin and / or the bisphenol type epoxy resin (A), for example, a melamine resin. Benzoguanamine resin, urea resin, polyisocyanate, blocked polyisocyanate, phenol resin and the like.
As said melamine resin, a part or all of methylol group of methylolation melamine is C1-C8 monohydric alcohol, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol , Partially etherified or fully etherified melamine resins etherified with i-butyl alcohol, 2-ethylbutanol, 2-ethylhexanol and the like.
Examples of commercially available products of the melamine resin include Uban 20SE-60, Uban 225 (all are trade names manufactured by Mitsui Chemicals, Inc.), Super Becamine G840, Super Becamine G821 (All are Dainippon Ink. Butyl etherified melamine resins such as Chemical Industry Co., Ltd. (trade name); Sumimar M-100, Sumimar M-40S, Sumimar M-55 (all of which are Sumitomo Chemical Co., Ltd., trade name), Cymel 202, Cymel 232 , Cymel 235, Cymel 254, Cymel 266, Cymel 272, Cymel 303, Cymel 325, Cymel 327, Cymel 350, Cymel 370 (above, Daicel Ornex Co., Ltd., trade name), Nicarac MS17, Nicarac MX15, Nicarac MX430, Methyl etherified melamine resins such as Carac MX600 (all are trade names manufactured by Sanwa Chemical Co., Ltd.) and Resimin 741 (trade names manufactured by Monsanto Co., Ltd.); Cymel 235, Cymel 202, Cymel 232S, Cymel 238, Cymel 254, Cymel 272, Cymel 1130 (above, Daicel Ornex Co., Ltd., trade name), Sumamiru M66B (Sumitomo Chemical Co., Ltd., trade name) and other methylated and isobutylated etherified melamine resins; Cymel XV805 (Made by Daicel Ornex Co., Ltd., trade name), Nicalac MS95 (trade name, produced by Sanwa Chemical Co., Ltd.), etc.

Examples of the benzoguanamine resin include methylolated benzoguanamine resins obtained by reacting benzoguanamine with aldehydes. Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like. In addition, those obtained by etherifying this methylolated benzoguanamine resin with one or more alcohols are also included in the benzoguanamine resin. Examples of the alcohol used for etherification include monohydric alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylbutanol, and 2-ethylhexanol. . Among these, a benzoguanamine resin obtained by etherifying at least a part of the methylol group of the methylolated benzoguanamine resin with a monohydric alcohol having 1 to 4 carbon atoms is preferable.
Specific examples of the benzoguanamine resin include, for example, My Coat 102, My Coat 105, My Coat 106 (manufactured by Daicel Ornex Co., Ltd.), Nicarak SB-201, Nicarac SB-203, Nicarac SB-301, Nicarac SB. -303, Nikalac SB-401 (all are manufactured by Sanwa Chemical Co., Ltd.) and other methyl etherified benzoguanamine resins; Cymel 1123 (above, manufactured by Daicel Ornex Co., Ltd.) and other mixed ethers of methyl ether and ethyl ether Benzoguanamine resin; Mecote 136 (above, manufactured by Daicel Ornex Co., Ltd.), Nikalac SB-255, Nikalac SB-355, Nikalac BX-37, Nikalac BX-4000 (above, all manufactured by Sanwa Chemical Co., Ltd.) Etherified benzoguanamine resin between ether and butyl ether; Mycoat 1128 (manufactured by Daicel Orunekusu Ltd.) and the like butyl etherified benzoguanamine resins such as.

  The urea resin is obtained by a condensation reaction between urea and formaldehyde, and can be dissolved or dispersed in a solvent or water.

  Examples of the polyisocyanate compound include compounds having two or more isocyanate groups in one molecule, for example, aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate; tetramethylene diisocyanate, hexamethylene diisocyanate, dimer Aliphatic diisocyanates such as acid diisocyanate and lysine diisocyanate; Alicyclic diisocyanates such as methylene bis (cyclohexyl isocyanate), isophorone diisocyanate, methylcyclohexane diisocyanate, cyclohexane diisocyanate, and cyclopentane diisocyanate; Addendum; this Et polyisocyanate and a low molecular weight or high molecular weight polyol compound (e.g., acrylic polyols, polyester polyols, polyether polyols, etc.) and there may be cited an isocyanate group excess obtained by reacting the free isocyanate group-containing prepolymer.

  Furthermore, as the polyisocyanate compound, the free isocyanate group of the polyisocyanate compound is a phenol compound, oxime compound, active methylene compound, lactam compound, alcohol compound, mercaptan compound, acid amide compound, imide compound, amine compound, imidazole. Blocked polyisocyanates blocked with a blocking agent such as a series compound, a urea series compound, a carbamic acid series compound, or an imine series compound can also be used.

  Examples of the phenol resin include a resol type phenol resin in which a phenol and a formaldehyde are heated in the presence of a reaction catalyst to cause a condensation reaction to introduce a methylol group.

  Phenols used for the production of phenol resins include bifunctional phenols such as o-cresol, p-cresol, p-tert-butylphenol, p-ethylphenol, 2,3-xylenol, 2,5-xylenol; , M-cresol, m-ethylphenol, 3,5-xylenol, m-methoxyphenol and the like; bis (4-hydroxyphenyl) -2,2-propane [bisphenol A], bis (4-hydroxy Examples thereof include tetrafunctional phenols such as phenyl) methane [bisphenol F], and these can be used alone or in admixture of two or more.

  Formaldehydes used for the production of phenolic resins include formaldehyde, paraformaldehyde, trioxane and the like, and these can be used alone or in combination of two or more. Further, as the phenol resin, a methylolated phenol resin obtained by alkyl etherifying a part of the methylol group can also be used. As the alcohol used for the alkyl etherification, a monohydric alcohol having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms is suitable, and examples thereof include methanol, ethanol, n-butanol, and isobutanol. it can.

  Commercially available phenolic resins include Shounol BKM-262, Shoonol BRG-555, Shoonol BRG-556, Shoonol BRG-558, Shoonol CKM-923, Shoonol CKM-983, Shoonol BKM-2620, Shoonol BRL-2854, Shoonol BRG-5590M, Shoonol CKS-3898, Shoonol CKS-3877A, Shoonol CKM-937, Shoonol CKS-394 (above, Showa Polymer Co., Ltd.), Hitanol 3305N (Hitachi Chemical) Manufactured by Kogyo Co., Ltd.), PHENOLITE TD-2131, PHENOLITE TD-2106, PHENOLITE TD-2093, PHENOLITE TD-2091, PHENOLITE TD-2090, PHENOLIT VH-4150, PHENOLITE VH-4170, PHENOLITE VH-4240, PHENOLITE KH-1160, PHENOLITE KH-1163, PHENOLITE KH-1165, PHENOLITE TD-2093-60F, PHENOLITE TD-20E60L60L -6161, PHENOLITE LF-4871, PHENOLITE LA-7052, PHENOLITE LA-7054, PHENOLITE LA-7751, PHENOLITE LA-1356, PHENOLITE LA-3018-50P (manufactured by DIC).

  The mixing ratio of the hydroxyl group-containing polyester resin and / or the bisphenol type epoxy resin (A) and the curing agent (B) is based on the total solid content of 100 parts by mass, and in terms of solid content, the hydroxyl group-containing polyester resin and / or Bisphenol-type epoxy resin (A) 60 to 90 parts by mass, preferably 70 to 88 parts by mass, curing agent (B) 10 to 40 parts by mass, preferably 12 to 30 parts by mass, workability and liner adhesion From the point of view, it is preferable.

Fatty acid ester (C)
The coating composition for metal caps of the present invention is for the purpose of improving cap opening performance.
A fatty acid ester (C) is blended.

  As the fatty acid ester (C), for example, Asa seed oil, linseed oil, Eno oil, Ochishika oil, olive oil, cacao oil, kapok oil, kayak oil, mustard oil, kyounin oil, kiri oil, kukui oil, walnut oil, Poppy oil, sesame oil, safflower oil, radish seed oil, soybean oil, daikon oil, refined camellia oil, corn oil, rapeseed oil, niger oil, nuka oil, palm oil, castor oil, sunflower oil, almond oil, grape seed Oil, gentian oil, pine seed oil, cottonseed oil, coconut oil, peanut oil, dehydrated castor oil, and the like. In particular, the fatty acid ester (C) having little odor is useful, and examples thereof include olive oil and almond oil.

  Commercially available products of such fatty acid esters (C) include chrome pure OL, chrome pure almond, chrome pure avocado, chrome pure macadamia, chrome pure tea oil (above, trade name, room temperature liquid) manufactured by Croda Japan Co., Ltd., chrome pure. Examples include cupas and chrome pure shea butter (made by Croda Japan Co., Ltd., trade name, solid at room temperature).

  The fatty acid ester (C) used in the metal cap coating composition of the present invention has an iodine value of 10 to 110, preferably 50 to 110, and more preferably 70 to 100. Desirable for. In addition, the iodine value was calculated | required according to the industrial hardened oil and fatty acid test method prescribed | regulated to JISK33317.5 (2009).

  Conventionally, the fatty acid ester (C) having a high iodine value is not easily used because it is easily oxidized and impairs the stability of the paint. However, since the coating composition for metal caps of the present invention contains the antioxidant (D), the fatty acid ester (C) is hardly oxidized, and a wide range of iodine value fatty acid esters (C) can be used. it can. For this reason, the cap openability can be improved without impairing the coating stability, coating film appearance, processability and liner adhesion.

  In addition, the freezing point of the fatty acid ester (C) is 10 ° C. or lower, preferably 0 ° C. or lower, and it is preferable that the fatty acid ester (C) is liquid at room temperature for cap opening.

  As a compounding quantity of the fatty acid ester (C) in the coating composition for metal caps of the present invention, the total solid content of the hydroxyl group-containing polyester resin and / or bisphenol type epoxy resin (A) and the curing agent (B) is 100 parts by mass. On the other hand, 0.1 to 10 parts by mass, preferably 0.5 to 8 parts by mass, and more preferably 1 to 5 parts by mass is desirable for workability and cap opening.

Antioxidant (D)
As the metal cap coating composition of the present invention, an antioxidant (D) is blended for the purpose of preventing the fatty acid ester (C) from being oxidized. Examples of the antioxidant (D) include hindered phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants and hindered amine-based antioxidants. Among these antioxidants (D), hindered phenol-based antioxidants are preferable for improving cap opening and liner adhesion.

  Examples of the hindered phenol antioxidant include triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3. -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino ) -1,3,5-triazine, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t -Butyl-4-hydroxy-hydrocinnamamide), 3,5-di-t-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-hydroxybenzyl) benzene, bis (3,5-di-tert-butyl-4-hydroxybenzylphosphonate ethyl) calcium, tris (3,5-di-tert-butyl- Hydroxybenzyl) -isocyanolate, octylated diphenylamine, 2,4-bis-[(n-octylthio) methyl] -o-cresol, isooctyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) Propionate, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2'-thio-diethylenebis [3- (3,5-di- t-butyl-4-hydroxyphenyl) propionate]. In particular, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2'-thio-diethylenebis [3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionate] is preferred.

  Examples of the phosphorus-based antioxidant include tris (2,4-di-t-butylphenyl) phosphite and tetrakis (2,4-di-t-butylphenyl) -4,4-biphenylenephosnite.

Examples of the hindered amine compound include dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine condensate, poly [{6- (1,1,3, , 3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino}]
N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N (1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1, 3,5-triazine condensate is mentioned.

  Examples of the sulfur-based antioxidant include dilauryl 3,3′-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, and the like.

  Commercially available products of the antioxidant (D) include, for example, Irganox 1035, Irganox 1010, Irganox 1076 (above, trade name, hindered phenol antioxidants manufactured by BASF), Anox20, Anox29, Anox70. , AnoxPP18 (above, ADDIBANT, trade name, hindered phenol antioxidant), ADK STAB PEP-8, ADK STAB HP-10 series, ADK STAB 2112 (above, trade name, phosphorus antioxidant manufactured by ADKA) Irgaphos 168 (trade name, phosphorus antioxidant manufactured by BASF). TINUVIN 622 LD, CHIMASSORB 119 FL, CHIMASSORB 944 LD (above, BASF, trade name, hindered amine compound antioxidant).

  Antioxidant (D) can also use 2 or more types of antioxidant together. In this case, it is preferable to use at least two types of at least one from a hindered phenol-based antioxidant and at least one from a phosphorus-based antioxidant in order to improve liner adhesion.

  The compounding quantity of the said antioxidant (D) is 0.05-10 mass with respect to 100 mass parts of solid content total of a hydroxyl-containing polyester resin and / or a bisphenol-type epoxy resin (A), and a hardening | curing agent (B). Part, preferably 0.1 to 5 parts by weight, more preferably 0.3 to 3 parts by weight is desirable for improving cap opening and liner adhesion.

Oxidized polyolefin (E)
Oxidized polyolefin (E) can be blended in the metal cap coating composition of the present invention. Oxidized polyolefin (E) is a resin particle pulverized in a dry state, or a resin particle that is heated and dissolved in an organic solvent and then cooled to precipitate particles in the organic solvent. Specifically, polyethylene oxide, ethylene -A (meth) acrylic acid copolymer etc. are mentioned.

  The resin particles have a maximum particle size of 50 μm or less, preferably 5 to 30 μm, an acid value of 0.5 to 40 mg KOH / g, preferably 10 to 25 mg KOH / g, and a melting point of 90 to 140 ° C., preferably 90 to 120 ° C. A range is preferred. The maximum particle size was determined by observing photographs with an electron microscope.

  Commercially available products of the above-mentioned oxidized polyolefin (E) are Petrolite E-2020 (trade name, manufactured by Toyo Petrolite Co., Ltd.), 4202E (trade name, manufactured by Mitsui Chemicals), A-C629, A-C680, A-. C316A (manufactured by Honeywell, trade name), Nucrel AN4214C, Nucrel N0903HC, Nucrel N0908C, Nucrel N410, Nucrel N1035, Nucrel N1050H, Nucrel N1108C, Nucrel N1110H, Nucrel N1207N, Nucrel N1 215N , Nukurel N2050H, Nukurel N2060, AN4311, Nukuleru AN4213C, Nukurel N035C, etc. Michal Co., Ltd., trade name), UN-8, PEX-101 (or more, Kyoyo Chemical Co., Ltd., trade name), high flat 2325 (Gifu Seratsuku Mills Ltd., trade name) and the like.

  As a compounding quantity of the said oxidized polyolefin (E), 1-15 mass parts with respect to 100 mass parts of solid content total of a hydroxyl-containing polyester resin and / or a bisphenol type epoxy resin (A), and a hardening | curing agent (B), The content of 1 to 10 parts by mass, more preferably 2 to 6 parts by mass is desirable for cap opening and liner adhesion.

Novolac epoxy resin (F)
A novolac type epoxy resin (F) can be mix | blended with the coating composition for metal caps of this invention as needed for workability improvement. As said novolak-type epoxy resin (F), a phenol novolak-type epoxy resin, a cresol novolak-type epoxy resin, other novolak-type epoxy resins, etc. can be mentioned, for example.
Commercially available products of the above-mentioned novolac type epoxy resin (F) are phenol novolak type epoxy resins, jER152, jER154 (above, Mitsubishi Chemical Corporation, trade name), EPPN-201 (Nippon Kayaku Co., Ltd., trade name). Epototo YDPN-638 (trade name, manufactured by Toto Kasei Co., Ltd.), DEN431, DEN485, DEN438 (trade name, manufactured by Dow Chemical Co., Ltd.), and the like.

  As commercial products of the above cresol novolac type epoxy resin, jER180S65, jER180H65 (trade name, manufactured by Mitsubishi Chemical Corporation), EOCN-102S, EOCN-103S, EOCN-104S (trade name, manufactured by Nippon Kayaku Co., Ltd., trade name) ), Epotot YDCN-701, Epotot-702, Epotot-703, Epotot-704 (above, manufactured by Tohto Kasei Co., Ltd., trade name), Araldite ECN1235, ECN1273, ECN1280 (above, made by Huntsman Corporation, trade name), etc. Can be mentioned.

  As other commercial products of the above-mentioned novolak type epoxy resins, Epotot ZX-1071T, Epotot ZX-1015, Epotot ZX-1247, Epotot YDG-414S (the above-mentioned, product name, manufactured by Toto Kasei Co., Ltd.) can be exemplified.

  When the above novolac type epoxy resin (F) is blended, the blending amount is based on 100 parts by mass of the total solid content of the hydroxyl group-containing polyester resin and / or the bisphenol type epoxy resin (A) and the curing agent (B). 1 to 15 parts by mass, preferably 2 to 12 parts by mass, and more preferably 3 to 9 parts by mass is desirable for improving workability.

  Further, the coating composition for a metal cap of the present invention includes, as necessary, other components such as a lubricity imparting agent, an organic solvent, a coloring pigment, an extender pigment, an antirust pigment, an anti-aggregation agent, and a leveling agent. An antifoaming agent, an ultraviolet absorber, a curing catalyst, and the like can be blended.

  Examples of the lubricity-imparting agent include silicon wax, fluorine wax, polyolefin wax, lanolin wax, montan wax, paraffin wax, microcrystalline wax, carnauba wax and the like. Two or more of these lubricity-imparting agents can be mixed.

  Examples of the organic solvent include hydrocarbon solvents such as toluene, xylene, Swazol 1000 (trade name, manufactured by Maruzen Petrochemical Co., Ltd.), high-boiling petroleum hydrocarbons; methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, etc. Ketone solvents; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate; alcohol solvents such as methanol, ethanol, butanol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, Examples include glycol ether solvents such as diethylene glycol monobutyl ether, which can be used alone or in admixture of two or more. .

  Examples of the colored pigment include titanium oxide, carbon black, colored mica, azo pigments (azomethine metal complex, condensed azo, etc.), iron oxide, and the like. Examples of the extender pigment include calcium carbonate, barium sulfate, hydrous magnesium silicate (talc), magnesium carbonate, calcium sulfate (gypsum), diatomaceous earth, mica (mica powder), and silica. Examples of the rust preventive pigment include zinc oxide, phosphite compounds, phosphate compounds, molybdate compounds, bismuth compounds, and metal ion exchange silica.

  Preferred examples of the curing catalyst include sulfonic acid compounds. Specific examples include dodecylbenzenesulfonic acid, dibutylbenzenesulfonic acid, dodecylnaphthalenesulfonic acid, dinonylnaphthalenesulfonic acid, and dinonylnaphthalenedisulfonic acid. Higher alkyl aryl sulfonic acids such as these and salts thereof (for example, amine compounds, ammonia and the like).

  The coating composition for a metal cap of the present invention can form a coating film suitable for a metal cap by coating and baking the outer surface and / or the inner surface of the cap processed metal plate or metal plate.

    As the metal plate used for the metal cap, any metal plate that can be used for beverage cans, cans for cans, caps and the like can be used. For example, aluminum plates, tin-free steel plates, tin plates, etc. Can be mentioned.

  The metal cap coating composition of the present invention is applied by a coating method such as roll coater coating or spray coating so that the coating film thickness is 1 to 20 μm, preferably 2 to 10 μm in terms of dry film thickness. The baking condition for the coating is usually about 120 to 300 ° C., preferably 150 to 200 ° C. for about 10 seconds to 30 minutes, preferably about 15 seconds to about 15 minutes for a metal plate. It is a metal plate coated with a coating film. The metal plate having the coating film is molded into the shape of a metal cap, and then a polyethylene liner is pressure-bonded onto the metal plate coated with the coating film to form a metal cap.

  Hereinafter, the present invention will be described in more detail with reference to Production Examples, Examples, and Comparative Examples, but the present invention is not limited thereto. In the following description, “part by mass” is abbreviated as “part”, and “mass%” is abbreviated as “%”.

Production and Production Example 1 of Hydroxyl-Containing Polyester Resin Polyester Resin Solution No. 1 1 TP-290 (Nippon Gosei Co., Ltd., polyester resin, number average molecular weight 17,000)
0, hydroxyl value 5.5 mgKOH / g, acid value 1.5 mgKOH / g) was dissolved and diluted with mixed solvent A (Note 1) to obtain a polyester resin solution No. 40 having a solid content of 40%. 1 was obtained.
(Note 1) Mixed solvent A: Solvesso 150 (manufactured by Esso Petroleum Corporation, high-boiling aromatic hydrocarbon solvent) / cyclohexanone = 70/30 (mass ratio)
Production Example 2 Polyester resin solution No. Production of No. 2 Byron GK-880 (manufactured by Toyobo Co., Ltd., polyester resin, number average molecular weight 22,000, hydroxyl value 4.5 mgKOH / g, acid value 1.0 mgKOH / g) was dissolved in mixed solvent A (Note 1). After dilution, a polyester resin solution No. 40 having a solid content of 40% was obtained. 2 was obtained.

Production Example 3 Polyester resin solution No. Production of No. 3 Byron GK-140 (manufactured by Toyobo Co., Ltd., polyester resin, number average molecular weight 13,000, acid value 2.0 mg KOH / g) was dissolved and diluted with mixed solvent A (Note 1) to obtain a solid content of 40 % Polyester resin solution No. 3 was obtained.

Production and production example 4 of oxidized polyolefin (E) 1 production
In a flask, 100 parts of A-C629 (Note 2) and mixed solvent B (Note 3) were blended, dissolved by heating and mixing at 130 ° C. for 1 hour, and further cooled to disperse the oxidized polyolefin having a solid content of 5%. Liquid No. 1 was obtained.

(Note 2) A-C629: manufactured by Honeywell, trade name, oxidized polyolefin, acid value 15 mg KOH / g, melting point 101 ° C.
(Note 3) Mixed solvent B: Swazol 1000 (manufactured by Maruzen Petrochemical Co., Ltd.) / Cyclohexanone = 50/50 (mass ratio).

Production Example 5 Oxidized polyolefin dispersion No. Production of No. 2 In a flask, 100 parts of A-C316A (Note 4) and mixed solvent B (Note 3) were blended, dissolved by heating and mixing at 130 ° C. for 1 hour, and further cooled to a solid content of 5%. Oxidized polyolefin dispersion No. 2 was obtained.
(Note 4) A-C316A: manufactured by Honeywell, trade name, oxidized polyolefin, acid value 16 mgKOH / g, melting point 140 ° C.

Example 1 Metal cap paint No. 1 1 production
Polyester resin solution No. obtained in Production Example 1 1 is 207.5 parts (83 parts in solid content), Cymel 350 (Note 6) is 17 parts (solid content), Cropure Almond (Note 9) is 2 parts, Anox20 (Note 12) is 0.5 parts, Polyolefin oxide Dispersion No. 1 was mixed with 60 parts (solid content 3 parts) and dodecylbenzenesulfonic acid 0.5 part, mixed solvent A (see Note 1) was added to adjust, and a metal cap paint No. 1 having a solid content of 12% was prepared. 1 was obtained.

Examples 2-30 Paint No. for metal cap 2-No. Production of No. 30 The same procedure as in Example 1 was conducted except that the formulations shown in Tables 1 and 2 were used. 2-No. 30 was obtained.

(Note 5) jER1007: manufactured by Mitsubishi Chemical Corporation, trade name, bisphenol A type epoxy resin, epoxy equivalent 1,800
(Note 6) Cymel 350: manufactured by Daicel Ornex Co., Ltd., trade name, fully alkyl type methylated melamine resin, curing agent (Note 7) Cymel 701: manufactured by Daicel Ornex Co., Ltd., trade name, imino group-containing methylated melamine resin , Hardener
(Note 8) Shounol CKS-394: Showa High Polymer Co., Ltd., Cresol / Bisphenol A type phenol resin, curing agent (Note 9) Cropure Almond: Croda Japan Co., Ltd., trade name, fatty acid ester (almond oil) , Iodine value 103, room temperature liquid (Note 10) Cropure OL: manufactured by Croda Japan Co., Ltd., trade name, fatty acid ester (olive oil), iodine value 81, room temperature liquid (Note 11) chrome pure shea butter: manufactured by Croda Japan Co., Ltd., Product name, fatty acid ester, iodine number 59.3, solid at room temperature (Note 12) Anox20: manufactured by ADDIBANT, product name, hindered phenol antioxidant (Note 13) Anox70: manufactured by ADDIBANT, product name, hindered phenol -Based antioxidants (Note 14) Irgaphos 168: BASF Product name, phosphate-based antioxidant (Note 15) UN-8: manufactured by Koyo Chemical Co., Ltd., product name, acid value 30 mgKOH / g, melting point 130 ° C., average particle size 3.5 μm, oxidized polyolefin dispersion (Note 16) ) PEX-101: manufactured by Koyo Chemical Co., Ltd., trade name, acid value 30 mg KOH / g, melting point 130 ° C., average particle size 4.9 μm, oxidized polyolefin dispersion (Note 17) DEN-438: trade name manufactured by Dow Chemical Co., Ltd. , Novolac epoxy resin, epoxy equivalent 178
(Note 18) jER152: trade name, novolac epoxy resin, novolac epoxy resin, epoxy equivalent 177, manufactured by Mitsubishi Chemical Corporation.

Comparative Examples 1-15
Except for the formulation shown in Table 3, the same procedure as in Example 1 was carried out to obtain a metal cap paint No. 12 having a solid content of 12%. 31-No. 45 was obtained.

Preparation of test coating plate The paint obtained in the example and comparative example was applied to a # 3105 aluminum plate with a thickness of 0.24 mm so that the dry film thickness was 4 μm, and the maximum temperature reached by the material with hot air at a wind speed of 3 m / sec ( Each test coating plate was obtained by baking for 10 minutes under the condition that the PMT was 180 ° C. About each obtained test coating plate, the test was done based on the following test method. The test results are also shown in Tables 1 to 3.

(Note 19) Coating film appearance: The coating film appearance of the test coating plate was observed with the naked eye.
○ indicates that there are no paint surface abnormalities such as repellency, dents or cloudiness on the paint surface.
Δ indicates any repellency, dent or cloudiness on the coating surface. × indicates that at least one coating surface abnormality such as cissing, dent or cloudiness is marked on the coating surface.

(Note 20) Workability: A cup was prepared by using a punch with a diameter of 33 mm, a blank diameter of 60 mm, and a coating surface on the outer surface side using a deep drawing tester manufactured by Eriksen Co., Ltd. After the cup was immersed in boiling water at 100 ° C. for 1 hour, an adhesion test was performed on the processed side surface portion on the outer surface side. The evaluation criteria are as follows.
A: No peeling of the coating film was observed, and no scratch was observed on the coating film surface.
O: peeling of the coating film is not observed, but scratches are observed on the coating film surface.
Δ indicates slight peeling of the coating film.
In x, peeling of the coating film is remarkably recognized.

(Note 21) Cap openability:
Using the test coating plate, the dynamic friction coefficient (μ value) was determined using Eagan slip tester model No. 225-3 (manufactured by Swing Albert Instruments Company, trade name, dynamic friction coefficient measuring instrument, pulling speed 10 cm / min). It was measured.
◎ indicates that the dynamic friction coefficient (μ value) is less than 0.03 and the cap opening performance is extremely good. ○ indicates that the dynamic friction coefficient (μ value) is 0.03 or more and less than 0.05, and the cap opening performance is low. Good △ indicates that the dynamic friction coefficient (μ value) is 0.05 or more and less than 0.07, and the cap opening property is poor. × indicates that the dynamic friction coefficient (μ value) is 0.07 or more and the cap opening property is low. Remarkably inferior.

(Note 22) Liner adhesion: A substitute characteristic related to liner adhesion of a cap.
Immediately after creating the test coating plate (initial stage) and after the test coating plate was left standing at room temperature for 10 days, on a heater heated to 130 ° C. with a 2 cm wide polyethylene liner material as shown in FIG. Heat for 20 seconds. At this time, an external force (8 in FIG. 2) of 0.25 MPa / cm ² is applied as a load on the liner material.
Next, after cooling the test coated plate to which the liner material was pressure-bonded in a thermostatic chamber at 20 ° C., the test plate to which the liner material was pressure-bonded was attached to the autograph as shown in FIG. This is referred to as a T peel test in which “strength” is measured.
◎: Tensile strength of 20 N / cm or more ○: Tensile strength of 15 N / cm or more and less than 20 N / cm Δ: Tensile strength of 10 N / cm or more and less than 15 N / cm ×: Tensile strength of 10 N / cm less than cm

  A metal cap having a coating film having excellent coating film appearance, processability, cap opening ability and liner adhesion can be provided.

1. Top surface part 2. 2. Side torso Skirt part4. 4. Coating film with metal cap coating composition Liner material6. Paint plate7. Heater 8. Apply external force9. 9. Fixing jig for measuring sample Liner 11. Painted board

Claims (6)

A coating composition containing a hydroxyl group-containing polyester resin and / or a bisphenol type epoxy resin (A), a curing agent (B), a fatty acid ester (C), an antioxidant (D) and an oxidized polyolefin (E), 0.1 to 10 parts by mass of fatty acid ester (C) and antioxidant (D) with respect to 100 parts by mass in total of the solid content of the polyester resin and / or bisphenol type epoxy resin (A) and curing agent (B) ) And 0.05 to 10 parts by mass of the oxidized polyolefin (E), and 1 to 15 parts by mass of the oxidized polyolefin (E). The novolak type epoxy resin (F) is contained in an amount of 1 to 15 parts by mass with respect to 100 parts by mass in total of the solid content of the hydroxyl group-containing polyester resin and / or the bisphenol type epoxy resin (A) and the curing agent (B). The coating composition for metal caps as described in 2. The coating composition for metal caps according to claim 1 or 2, wherein the fatty acid ester (C) is liquid at normal temperature. The metal cap coating composition according to any one of claims 1 to 3, wherein the fatty acid ester (C) has an iodine value of 10 to 110. The coating composition for a metal cap according to any one of claims 1 to 4, comprising at least two kinds of antioxidants (D). The metal cap formed by coating the coating composition for metal caps of any one of Claims 1-5.

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