JP2009173705A - Adhesive for metal can outer surface, and polyester film laminated metal plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive for a metal can outer surface used for manufacturing a polyester film laminated metal plate and being excellent in an anti-blocking property, and a polyester film laminated metal plate using the adhesive. <P>SOLUTION: The adhesive for the metal can outer surface contains 0.1-30 pts.mass of a crosslinking agent (B) and 0.3-10 pts.mass of an acrylic resin (C) having the following characteristics based on 100 pts.mass of a polyester resin (A) having a number average molecular weight of 5,000-60,000 and a glass transition temperature in a range of 30-80°C. The acrylic resin (C) is obtained by being subjected to a copolymerization reaction of a monomer component comprising 5-95 pts.mass of at least one of monomer (c1) selected from isobornyl acrylate, isobornyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate, 5-30 pts.mass of a hydroxyl group-containing polymerizable unsaturated monomer (c2) and 0-90 pts.mass of another polymerizable unsaturated monomer (c3) based on the total pts.mass of the constitution monomer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an adhesive for outer surface of a metal can excellent in blocking resistance used for production of a polyester film-bonded metal plate and a polyester film-bonded metal plate using the adhesive.

  Conventionally, for film laminated cans, for example, an adhesive is applied to the adhesive surface of a plastic film such as a polyester (PET) film with a roll coater, and this is bonded to a metal plate such as a steel plate and then molded into a can. It is manufactured by a method of attaching to a can that has been directly molded, or as an adhesive for film lamination used there, adhesives such as epoxy resin and polyester resin are known. Yes.

Polyester film laminate cans are usually wound on a polyester film after applying an adhesive to the polyester film, volatilizing the solvent in the adhesive by heating, etc., and drying the adhesive layer to an extent that does not cure. A polyester film having an adhesive layer can be obtained by bonding to a molded can or a metal plate and heat curing or electron beam curing.
Conventionally, a polyester film-laminated metal plate (hereinafter sometimes referred to as a “PET laminated metal plate”) used for beverage cans or food cans is usually composed of a polyester film and a metal plate via an adhesive. They are stacked (Patent Document 1).

  For example, (1) a polyester film, which is a transparent plastic film, is printed with an ink as needed and dried, and then coated with an adhesive and dried until tack-free (usually) (2) Heating (usually about 180 ° C. for about 0.5 seconds) and press-bonding the polyester film on which the adhesive layer is formed and the metal plate to cure. It consists of the process to make.

  Also, an electron beam curable adhesive is used as an adhesive, and after a polyester film having an ink layer is bonded to a metal plate via an electron beam curable adhesive, an electron beam is irradiated through the polyester film and cured. A method for obtaining a film-laminated metal plate is disclosed (Patent Document 2).

  (A) 5 to 50 parts by weight of a polycaprolactone polymer and (C) 2 to 50 parts by weight of an o-cresol novolac type epoxy resin with respect to 100 parts by weight of a phenoxy resin containing a carboxy group. An electron beam curable adhesive is disclosed (Patent Document 3).

  In addition, (a) per 100 parts by weight of a hydroxyl group-containing polyester resin having a number average molecular weight in the range of 7,000 to 40,000, (b) 0.3 to 10 mol / kg of polymerizable unsaturated double 2 to 200 parts by weight of a polymerizable unsaturated polyester having a bond and a number average molecular weight in the range of 300 to 5,000, and (c) an average particle diameter in the range of 1 to 10 μm, and the softening point An electron beam curable adhesive containing 0.1 to 10 parts by weight of organic resin fine particles having a temperature in the range of 100 to 200 ° C. is disclosed (Patent Document 4).

  However, the polyester film in which the adhesive described in Patent Documents 1 to 4 is formed is usually wound into a coil after the adhesive layer is dried, and is stored until use. Can be pasted together. However, the laminated film has a problem that the coil blocks during storage and the coil cannot be unwound, and even if it is unwound, a part of the adhesive layer adheres to the back surface of the polyester film. In addition, if the curing of the adhesive layer is advanced too much to prevent blocking, there is a problem that the adhesive force between the adhesive layer and the metal plate becomes weak when the laminated film is bonded to the metal plate. .

JP-A-3-87249 JP-A-6-192637 JP-A-9-249867 Japanese Patent Laid-Open No. 2000-1660

  An object of the present invention is to laminate a metal can outer surface adhesive capable of forming an adhesive layer having good blocking resistance and excellent adhesion to a metal plate, and a laminated film having such an adhesive layer. The polyester film laminated metal plate is to provide a polyester film-laminated metal plate that can exhibit excellent performance in appearance, workability, retort resistance, and the like without occurrence of color unevenness.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a polyester resin (A) having a number average molecular weight of 5,000 to 60,000 and a glass transition temperature of 30 to 80 ° C., a crosslinking agent ( B), an adhesive containing a specific acrylic resin (C), and 0.1 to 30 parts by mass of a crosslinking agent (B) and a specific acrylic resin (C) with respect to 100 parts by mass of the polyester resin (A) ) It has been found that the above object can be achieved by using the metal can outer surface adhesive characterized by containing 0.3 to 10 parts by mass, and the present invention has been completed.

  The adhesive for outer surfaces of metal cans according to the present invention can form an adhesive layer having good blocking resistance and excellent adhesion to a metal plate. A polyester film laminated metal plate obtained by laminating a laminated film having an adhesive layer has no appearance of color unevenness and is excellent in appearance, and further has excellent properties such as laminate strength and retort resistance. The polyester film laminated metal plate using the adhesive of the present invention can be suitably used for can applications such as can lids and inner and outer surfaces of cans.

The present invention provides a metal can outer surface adhesive capable of forming an adhesive layer having good blocking resistance and excellent adhesion to a metal plate, and a polyester film obtained by laminating a laminated film having the adhesive layer. The present invention relates to a laminated metal plate.
Hereinafter, the metal can outer surface adhesive of the present invention and the polyester film laminated metal plate using the metal can outer surface adhesive will be described in detail.

[Adhesive for metal can outer surface]
Polyester resin (A)
The polyester resin (A) is an esterified product containing a polybasic acid component and a polyhydric alcohol component as main raw material components. Examples of the polybasic acid component include phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic acid, fumaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, anhydrous One or more dibasic acids selected from maleic acid, itaconic acid, dimer acid, and the like, and lower alkyl esterified products of these acids are mainly used, and benzoic acid, crotonic acid, pt-butylbenzoic acid as necessary. A tribasic or higher polybasic acid such as monobasic acid, trimellitic anhydride, methylcyclohexeric carboxylic acid, pyromellitic anhydride, etc. are used in combination.

Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 2-butyl-2-ethyl-1,3-propanediol, neopentyl glycol, 3-methylpentanediol, 1 Dihydric alcohols such as 1,4-hexanediol, 1,6-hexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, and bisphenol A propylene oxide adduct are mainly used. Depending on the above, trihydric or higher polyhydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol can be used in combination. These polyhydric alcohols can be used alone or in admixture of two or more.
The esterification or transesterification reaction of both components can be performed by a method known per se, for example, obtained by polycondensation of the polybasic acid component and the polyhydric alcohol component at a temperature of about 180 to 250 ° C. be able to. Furthermore, after obtaining a polyester having a hydroxyl group from a polybasic acid component and a polyhydric alcohol component, to the hydroxyl group of the polyester having a hydroxyl group, maleic acid, maleic anhydride, phthalic anhydride, trimellitic anhydride, adipic acid, A polyester resin having a carboxyl group introduced into the resin by reacting a polybasic acid such as azelaic acid can also be used.

  Moreover, about the polyester resin (A), you may use the urethane modified polyester resin by which chain extension was carried out by the urethanation reaction of a part of hydroxyl group in resin, and a polyisocyanate compound, and was high molecular weight. The urethane-modified polyester resin can also be obtained by subjecting a part of the hydroxyl group in the hydroxyl group-containing polyester resin to a urethanization reaction with a partially blocked polyisocyanate compound.

Examples of the polyisocyanate compound include aliphatics such as hexamethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, propylene diisocyanate, butylene diisocyanate, trimethylhexamethylene diisocyanate, xylylene diisocyanate, dimer diisocyanate, and lysine diisocyanate. Diisocyanate compounds; cycloaliphatic diisocyanate compounds such as isophorone diisocyanate, methylenebis (cyclohexyl isocyanate), methylcyclohexane diisocyanate, di (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, cyclopentane diisocyanate; Aromatic diisocyanate compounds such as nylmethane diisocyanate, naphthalene diisocyanate, toluidine diisocyanate, diphenyl ether diisocyanate, phenylene diisocyanate, biphenylene diisocyanate, dimethyl-biphenylene diisocyanate, isopropylidenebis (4-phenylisocyanate); triphenylmethane triisocyanate, Polyisocyanate compounds having 3 or more isocyanate groups in one molecule such as triisocyanatobenzene, triisocyanatotoluene, dimethyldiphenylmethanetetraisocyanate; ethylene glycol, propylene glycol, dimethylolpropionic acid, polyalkylene glycol, trimethylo -Isocyanate on the hydroxyl group of polyols such as Urethane adducts made by reacting polyisocyanate compounds in excess ratios of silicate groups; burettes such as hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, methylene bis (cyclohexyl isocyanate) Type adducts, isocyanate ring type adducts. These may be used alone or in combination of two or more.
Examples of the blocking agent used in the blocked polyisocyanate include oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenol compounds such as phenol, para-t-butylphenol and cresol; n-butanol and 2-ethyl. Aliphatic alcohols such as hexanol; Aromatic alkyl alcohols such as phenyl carbinol and methyl phenyl carbinol; Ether alcohol compounds such as ethylene glycol monobutyl ether and diethylene glycol monoethyl ether; Lactams such as ε-caprolactam and γ-butyrolactam System compounds; and the like.
The polyisocyanate compound may be a polyisocyanate compound in which an isocyanate group is not blocked, a partially blocked polyisocyanate compound in which a part of the isocyanate group in the molecule is blocked, and an isocyanate group in the molecule It may be a fully blocked polyisocyanate compound that is completely blocked. Moreover, these mixtures may be sufficient.

  The number average molecular weight (Note 1) of such a polyester resin (A) is 5,000 to 60,000, preferably 10,000 to 30,000, and the glass transition temperature (Note 2) is 30 to 30. 80 ° C., preferably 35 to 65 ° C., hydroxyl value 2 to 50 mg KOH / g, preferably 3 to 10 mg KOH / g, good blocking resistance and excellent adhesion to metal plate It is also preferable for forming an agent layer.

(Note 1) Number average molecular weight: In the present invention, the number average molecular weight or the weight average molecular weight was determined according to JIS K 0124-83. Using gel filtration chromatography, four separations of “TSKGEL4000HXL”, “G3000HXL”, “G2500HXL”, and “G2000HXL” (manufactured by Tosoh Corporation) are used at 40 ° C. and a flow rate of 1.0 ml / min. Using GPC tetrahydrofuran, the chromatogram obtained with an RI refractometer and the standard polystyrene calibration curve were used.
(Note 2) Glass transition temperature: The glass transition temperature (Tg) is determined by differential thermal analysis (DTA).

Cross-linking agent (B)
The adhesive for outer surfaces of metal cans of the present invention contains a crosslinking agent (B) in addition to the hydroxyl group-containing polyester resin (A).

  As the cross-linking agent (B), the polyester resin (A) and, in some cases, the polymerizable unsaturated oligomer (D) having a polymerizable unsaturated double bond described later react by heating or the like to adhere to the outer surface of the metal can. For example, a polyisocyanate compound which may be blocked, an amino resin, and the like can be mentioned. Among them, a blocked polyisocyanate compound is preferable from the viewpoint of adhesion to the polyester film surface. It is.

  The polyisocyanate compound may be a polyisocyanate compound in which isocyanate groups are not blocked, a blocked polyisocyanate compound in which isocyanate groups in the molecule are blocked, or a mixture thereof. It may be. As specific examples of the polyisocyanate compound and the blocking agent, the polyisocyanate compound and the blocking agent can be used.

  The amount of the crosslinking agent (B) is 0.1 to 30 parts by weight, preferably 5 to 25 parts by weight, more preferably 10 to 20 parts by weight per 100 parts by weight of the polyester resin (A). is there. The curing catalyst is blended for the purpose of promoting the reaction of the polyisocyanate compound. For example, tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexaate) is used. Nooate), dibutyltin dilaurate, dibutyltin oxide, dioctyltin oxide, and organometallic catalysts such as lead 2-ethylhexanoate are preferably used. When the curing catalyst is blended, the blending amount is 0.1 to 10 parts by weight, preferably 0.5 to 7 parts by weight, more preferably 1.0 to 5 parts per 100 parts by weight of the polyester resin (A). Within the range of parts by mass is preferred.

Acrylic resin (C)
The adhesive for outer surfaces of metal cans of the present invention is 0.3 to 10 parts by mass, preferably 0.5 to 7 parts by mass, more preferably 0 to 100 parts by mass of the polyester resin (A). .7-5 parts by mass. It is suitable to contain the acrylic resin (C) within this range from the viewpoint of improving retort resistance.

  The acrylic resin (C) is composed of at least one monomer (c1) selected from isobornyl acrylate, isobornyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate, a hydroxyl group-containing polymerizable unsaturated monomer (c2), and others. It is a hydroxyl group-containing copolymer resin having a monomer component composed of the polymerizable unsaturated monomer (c3) as a constituent component.

  Examples of the hydroxyl group-containing polymerizable unsaturated monomer (c2) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2,3-dihydroxybutyl (meta ) Monoesters of polyhydric alcohols such as acrylate, 4-hydroxybutyl (meth) acrylate and polyethylene glycol mono (meth) acrylate and acrylic acid or methacrylic acid; monoesters of the above polyhydric alcohols and acrylic acid or methacrylic acid Compounds obtained by ring-opening polymerization of ε-caprolactone to the compound, for example, “Placcel FA-1”, “Placcel FA-2”, “Placcel FA-3”, “Placcel FA-4”, “Placcel FA-5”, “ PLACCEL FM-1 "," PLAXEL FM- 2 ”,“ Plaxel FM-3 ”,“ Plaxel FM-4 ”,“ Plaxel FM-5 ”(all are trade names made by Daicel Chemical Co., Ltd.), etc. Can do. These can be used alone or in combination of two or more.

  Other polymerizable unsaturated monomers (hereinafter may be abbreviated as “other monomers (c3)”) are copolymerizable with the above components (c1) and (c2), and include isobornyl acrylate and isobornyl acrylate. It is a polymerizable unsaturated monomer other than at least one monomer (c1) selected from nyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate, and a hydroxyl group-containing polymerizable unsaturated monomer (c2).

As other monomer (c3), for example, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate Alkyl (meth) acrylates having 1 to 24 carbon atoms such as tert-butyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate; acrylic Carboxyl group-containing polymerizable unsaturated monomers such as acid, methacrylic acid, maleic acid and maleic anhydride; epoxy group-containing polymerizable unsaturated monomers such as glycidyl (meth) acrylate and 3,4-epoxycyclohexylmethyl (meth) acrylate Monomer; aminoalkyl (meth) acrylate such as N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate; acrylamide, methacrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-methylolacrylamide, N-methylolacrylamide methyl ether, N-methylol (Meth) acrylamide or derivatives thereof such as acrylamide butyl ether; acrylonitrile, methacrylonitrile, vinyl acetate, Veova monomer (manufactured by Shell Chemical), vinyl toluene, α-methyl Styrene and the like. These compounds can be used alone or in combination of two or more. “(Meth) acrylamide” means acrylamide or methacrylamide.
The blending ratio of each monomer constituting the acrylic resin (C) is at least 1 selected from isobornyl acrylate, isobornyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate based on the total mass part of all the constituent monomers. Seed monomer (c1) 5 to 95 parts by mass, preferably 20 to 60 parts by mass, more preferably 30 to 50 parts by mass, hydroxyl group-containing polymerizable unsaturated monomer (c2) 5 to 30 parts by mass, preferably 15 to 35 parts. The amount is in the range of mass parts, more preferably 20-30 mass parts, other monomer (c3) 0-90 mass parts, preferably 5-65 mass parts, more preferably 20-50 mass parts.

The at least one monomer (c1) selected from the above isobornyl acrylate, isobornyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate is 5-95 parts by mass, preferably 20-60 parts by mass, more preferably It is suitable from the point of blocking resistance that it exists in the range of 30-50 mass parts.
The amount of the hydroxyl group-containing polymerizable unsaturated monomer (c2) is preferably in the range of 5 to 30 parts by mass, preferably 15 to 35 parts by mass, and more preferably 20 to 30 parts by mass from the resistance to retort adhesion. is there.

  The acrylic resin (C) has a weight average molecular weight (see (Note 1)) in the range of 2,000 to 20,000, preferably 5,000 to 15,000. It is preferable that the hydroxyl value is in the range of 40 to 140 mgKOH / g, preferably 80 to 130 mgKOH / g, from the viewpoint of laminate strength. The glass transition temperature (see Note 2 above) is preferably 30 to 80 ° C., preferably 35 to 70 ° C.

  A polymerization method for obtaining the acrylic resin (C) by polymerizing the monomer components is not particularly limited, and is a polymerization method known per se, for example, a bulk polymerization method, a solution in the presence of a radical polymerization initiator. Among them, the solution polymerization method can be suitably used, such as a polymerization method and a bulk-suspension two-stage polymerization method in which suspension polymerization is performed after bulk polymerization.

  Examples of the radical polymerization initiator include ketone peroxides such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide; 1,1-bis (tert-butylperoxy) -3 , 3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, 2,2-bis (4,4- Ditert-butylperoxycyclohexyl) propane, 2,2-bis (4,4-ditert-amylperoxycyclohexyl) propane, 2,2-bis (4,4-ditert-hexylperoxycyclohexyl) propane, 2,2-bis (4,4-ditert-octylperoxycyclohexyl) propane, Peroxyketals such as 2,2-bis (4,4-dicumylperoxycyclohexyl) propane; hydroperoxides such as cumene hydroperoxide and 2,5-dimethylhexane-2,5-dihydroperoxide 1,3-bis (tert-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, diisopropylbenzene peroxide, tert-butylcumyl peroxide Dialkyl peroxides such as decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide and the like; peroxy such as bis (tert-butylcyclohexyl) peroxydicarbonate Carbonate Organic peroxide polymerization initiators such as peroxyesters such as tert-butylperoxybenzoate and 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, and 2,2′-azobis Examples include azo polymerization initiators such as isobutyronitrile and 1,1-azobis (cyclohexane-1-carbonitrile).

  As the polymerization method by the solution polymerization method, for example, the monomer mixture is dissolved or dispersed in an organic solvent and heated in the presence of the radical polymerization initiator, usually at a temperature of about 80 ° C. to 200 ° C. with stirring. A method can be mentioned. The reaction time is usually about 1 to 24 hours.

  Examples of the organic solvent include hydrocarbon solvents such as heptane, toluene, xylene, octane and mineral spirit; ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate and diethylene glycol monobutyl ether acetate; Ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone; alcohol solvents such as methanol, ethanol, isopropanol, n-butanol, sec-butanol, isobutanol; n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene Ether type such as glycol monoethyl ether; Swazol 310, Swazol 1000, Swazol 1500 (all Sumo Oil Co.) can be cited SHELLSOL A (Shellsol A, aromatic such as Shell Chemical Co.) petroleum solvent or the like. These organic solvents can be used alone or in combination of two or more.

Polymerizable unsaturated oligomer (D) having a polymerizable unsaturated double bond
The adhesive for metal can outer surfaces of the present invention is blended with a polymerizable unsaturated oligomer (D) having a polymerizable unsaturated double bond for the purpose of improving curability as needed.
A polymerizable unsaturated oligomer (D) having a polymerizable unsaturated double bond (hereinafter sometimes referred to as “polymerizable unsaturated oligomer (D)”) has a polymerizable unsaturated double bond in one molecule. It has one or more, preferably 2 to 4, and has a polymerizable unsaturated double bond in the oligomer (D) at a concentration of 3 to 15 mol / kg, preferably 5 to 10 mol / kg. And having a number average molecular weight of 200 to 2,000, preferably 300 to 1,500, and a hydroxyl value of 0 to 200 mgKOH / g, preferably 30 to 80 mgKOH / g.

The polymerizable unsaturated oligomer (D) is not particularly limited, and examples thereof include a modified polyester oligomer, an acrylic oligomer, a modified urethane oligomer, and a modified epoxy oligomer.
The modified polyester oligomer is obtained, for example, by introducing a polymerizable double bond by esterifying a polymerizable unsaturated carboxylic acid such as acrylic acid to a hydroxyl group-containing low molecular weight polyester having a number average molecular weight of about 1,900 or less. Can do.
Examples of commercially available modified polyester oligomers include Aronics M-7100, Aronics M-8100, Aronics M-9050 (all are trade names manufactured by Toa Gosei Chemical Co., Ltd.) and the like.
The acrylic oligomer is, for example, a low molecular weight acrylic resin having a functional group such as a hydroxyl group, a carboxyl group, and an epoxy group having a number average molecular weight of about 1,900 or less, and a reactive group having reactivity with the functional group in the acrylic resin. A polymerizable double bond is introduced into a low molecular weight acrylic resin by reacting a polymerizable unsaturated compound containing a polymerizable unsaturated group with a polymerizable unsaturated compound under conditions that do not cause the polymerizable unsaturated group to disappear. Can be obtained. As a commercial item of the said acrylic resin oligomer, Aronics M-305, Aronics M-450 (above, all are the Toa Gosei Chemical Co., Ltd. make, brand name) etc. can be mentioned, for example.

The modified urethane oligomer, for example, introduces a hydroxyl group by reacting isocyanuric acid with ethylene oxide, and this hydroxyl group-containing isocyanuric acid is functionally reactive with a hydroxyl group such as a carboxyl group-containing polymerizable unsaturated compound such as acrylic acid. It can be obtained by reacting a polymerizable unsaturated compound containing a group to introduce a polymerizable unsaturated group. Examples of commercially available modified urethane oligomers include Aronics M-315 and Aronics M-215 (all of which are trade names manufactured by Toa Gosei Chemical Co., Ltd.).
The modified epoxy oligomer introduces a polymerizable unsaturated group by, for example, reacting a carboxyl group-containing polymerizable unsaturated compound such as acrylic acid with an epoxy group-containing compound having one or more, preferably two or more epoxy groups. Can be obtained. In addition, trimethylolpropane triacrylate, pentaerythritol triacrylate, or the like can also be used.

In the adhesive of the present invention, the polymerizable unsaturated oligomer (D) can be used alone or in combination of two or more.
In the metal can outer surface adhesive of the present invention, the amount of the polymerizable unsaturated oligomer (D) is 0.1 to 30 parts by mass, preferably 2 to 15 per 100 parts by mass of the hydroxyl group-containing polyester resin (A). It is suitable from the point of blocking resistance, curability, adhesiveness, etc. to be within the range of parts by mass.

  In addition, the adhesive for the outer surface of the metal can of the present invention is usually a number average molecular weight of 600 to 3,000, more preferably 650 to 2, for the purpose of improving the adhesion between the metal plate and the polyester film, if necessary. 000 novolac type epoxy resin can be blended. Examples of the novolac type epoxy resin include a cresol novolac type epoxy resin and a phenol novolac type epoxy resin.

Examples of commercial products of the cresol novolac type epoxy resin include jER180S65, jER180H65 (all of which are manufactured by Japan Epoxy Resin Co., Ltd.), EOCN-102S, EOCN-103S, and EOCN-104S (all of which are Nippon Kayaku stocks). Epototo YDCN-701, Epototo YDCN-702, Epototo YDCN-703, Epototo YDCN-704 (all of which are manufactured by Tohto Kasei Co., Ltd.).
As a commercial item of the said phenol novolak-type epoxy resin, jER154 (made by Japan Epoxy Resin Co., Ltd.) and Epototo YDPN638 (made by Toto Kasei Co., Ltd.) are mentioned, for example.

  The compounding amount of the novolak type epoxy resin is 10 parts by mass or less, preferably 0.5 to 5 parts by mass, more preferably 1 to 7 parts by mass per 100 parts by mass of the hydroxyl group-containing polyester resin (A). It is.

Nylon fine particles can be added to the metal can outer surface adhesive of the present invention as necessary. By adding nylon fine particles, when the film is laminated to the material under high pressure, the adhesive between the film and the material is extruded to ensure a uniform film thickness, and the uneven film thickness part It is possible to suppress color unevenness due to the occurrence.
Further, for the purpose of improving the coating workability of the adhesive for the outer surface of the metal can of the present invention, an organic solvent, a curing catalyst, an antiblocking agent, a lubricity imparting agent, an antifoaming agent, a color pigment, A lubricity imparting agent, a silane coupling agent, an antifoaming agent, an antistatic agent, an organic solvent, and the like can be appropriately blended. Examples of the colored pigment include white pigments such as titanium oxide, other chromatic pigments, and bright pigments such as aluminum powder.

  Examples of the organic solvent include those that can dissolve or disperse the adhesive component, for example, toluene, xylene, hydrocarbon solvent such as Solvesso # 150 (manufactured by Esso Petroleum, high boiling hydrocarbon petroleum solvent), methyl ethyl ketone, methyl isobutyl ketone. And ketone solvents such as cyclohexanone, and ester solvents such as ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, and ethylene glycol monoethyl ether acetate. Can be appropriately selected and used.

As in the present invention, when a polyester laminated metal plate is used on the outer surface of a can, multicolor printing is usually applied, and a colored layer (usually a white coat) is required under the printing ink layer. If an adhesive containing a white pigment is used, it can also serve as a white coat, and one can omit the manufacturing process of the can, which is very advantageous.
The blending amount of the white pigment is not particularly limited as long as it does not impair the performance of the adhesive layer, but is usually 200 parts by mass, preferably 100 parts by mass with respect to 100 parts by mass of the polyester resin (A). The range of 10 to 150 parts by mass, more preferably 50 to 120 parts by mass is suitable.

  Examples of the bright pigment include aluminum, vapor-deposited aluminum thin film, aluminum oxide, mica, titanium oxide-coated mica, and iron oxide-coated mica. The blending amount of the glitter pigment is not particularly limited as long as it does not impair the performance of the adhesive layer, but is usually 0.1 to 20 with respect to 100 parts by mass of the polyester resin (A). A part by mass, preferably 1 to 15 parts by mass, more preferably 3 to 10 parts by mass is suitable.

  Further, the lubricity imparting agent is blended to impart lubricity to the adhesive surface, in order to smoothly wind up the laminated film for laminating a metal plate coated with the adhesive in a coil shape, It is blended for the purpose of preventing the adhesive layer surface from being damaged when the coil is unwound.

  Examples of the lubricity-imparting agent include fatty acid ester wax; polyolefin wax such as polyethylene wax; animal wax such as lanolin and beeswax; plant wax such as carnauba wax and water wax; microcrystalline wax, silicon wax, Mention may be made of waxes such as fluorine-based waxes.

[Production of polyester film-laminated metal sheet]
The polyester film-laminated metal plate is obtained by laminating a polyester film on one side or both sides of a metal plate via the adhesive layer. The adhesive layer needs to be electron beam cured at the final product stage.

  For example, a polyester film-laminated metal plate is formed by applying and drying the metal can outer surface adhesive of the present invention on Step 1: a polyester film, and Step 2: forming a polyester film having an adhesive layer on one side of the metal plate or It can be manufactured by aligning the adhesive layer surface of the polyester film on both sides and thermocompression bonding, and then step 3: curing the adhesive layer.

Step 1: The polyester film may be a polyester film itself that does not have an ink layer, or may be one in which an ink layer is formed on a polyester film. As the polyester film, those in which 75 to 100% of ester repeating units are composed of ethylene terephthalate units are suitable. Examples of the acid component of the ester unit other than the ethylene terephthalate unit include phthalic acid, isophthalic acid, succinic acid, and adipic acid. The polyester film may be subjected to surface treatment such as corona discharge treatment on its surface in order to improve adhesion with ink or adhesive, and is preferably subjected to surface treatment. . Although the film thickness of a polyester film is not specifically limited, Usually, about 5-30 micrometers is used suitably.
When the ink layer is formed on the polyester film, the ink for forming the ink layer can be an ink for a polyester film, and may be either a thermosetting type or actinic ray curable type ink. The ink may be applied by one color or two or more colors.
The ink layer can be formed by printing the ink on the polyester film by, for example, a gravure printing method, and removing or curing the solvent by heating, actinic ray irradiation, or the like, if necessary.

  Metal plate lamination by applying the adhesive of the present invention on a polyester film (if the polyester film has an ink layer, usually on the ink layer surface) and drying to form an adhesive layer having no surface tackiness A laminated film can be obtained.

Application of the adhesive of the present invention onto a polyester film is usually performed by a coating means known per se such as a roll coater method, a die coater method, a gravure method, a gravure offset method, a spray coating method, etc. For example, it is usually dried at a temperature of 50 to 180 ° C. to remove the solvent of the adhesive layer.
Next, the polyester film (laminated film for laminating metal plates) having the adhesive layer obtained in step 1 is wound into a coil shape. This coil is stored until it is used for bonding to a metal plate.

  Step 2: Next, the coil of the obtained laminated film for metal plate lamination is unwound and bonded to the metal plate. Examples of the metal plate used for the above bonding include hot rolled steel plate, cold rolled steel plate, hot dip galvanized steel plate, electrogalvanized steel plate, iron-zinc alloy plated steel plate, zinc-aluminum alloy plated steel plate, nickel-zinc. Metal plate materials such as alloy plated steel plate, nickel-tin alloy plated steel plate, tinplate, chrome plated steel plate, aluminum plated steel plate, turn plated steel plate, nickel plated steel plate, stainless steel, tin-free steel, aluminum plate, copper plate, titanium plate; Chemically treated metal plates that have been subjected to chemical conversion treatment, such as phosphate treatment, chromate treatment, composite oxide film treatment, etc .; primer layers such as white coat on the surface of these metal plate materials or chemical conversion treatment metal plates Examples thereof include a coated metal plate such as a primer-coated metal plate formed with a metal.

  In addition, the “metal plate” includes a processed metal plate in which a flat metal plate such as the above-described metal plate material, chemical conversion metal plate, or primer-coated metal plate is molded into a can body, for example. .

  The condition for laminating the metal plate on the surface of the adhesive layer of the laminated film for metal plate lamination is that the laminated film for metal plate lamination is not deteriorated, and the polyester film and the metal plate are sufficiently adhered to each other. The polyester laminated metal plate is not particularly limited as long as it can be obtained. As an example of the bonding conditions, for example, the temperature of the metal plate during thermocompression bonding is about 120 to 200 ° C. by a method using a heating roll or a method of preheating the metal plate, and in a short time (usually about 2 seconds or less). And a method of laminating a metal plate and a laminated film for laminating a metal plate by thermocompression bonding. When using a flat metal plate, the laminated film for laminating a metal plate can be heat-laminated on one or both sides of the flat metal plate.

Step 3: The adhesive layer of the laminated metal plate obtained as described above can be cured by heat drying, or heat drying and electron beam irradiation.
Heat drying is performed at 180 ° C. to 250 ° C., preferably 190 ° C. to 230 ° C. at a surface temperature of an object to be coated using a drying facility such as an electric hot air dryer or a gas hot air dryer. For 2 seconds, preferably 10 to 60 seconds.
The electron beam irradiation appropriately performed may be performed before or after the processing of the polyester laminated metal plate such as a flat plate. Of course, when the polyester laminated metal plate has a target shape, the polyester laminated metal plate irradiated with the electron beam may not be processed.

  Accelerators of electron beam sources used for electron beam irradiation include Cockcroft type, Cockcroft Walton type, Van De Graaf type, Resonant transformer type, Transformer type, Insulating core transformer type, Dynamitron type, Linear filament Mold, area beam type, high frequency type and the like. The electron beam energy required for curing the adhesive layer is suitably in the range of 100 keV to 300 keV, preferably 150 keV to 200 keV. The irradiation dose is preferably 0.2 Mrad to 15 Mrad, and particularly preferably 1 Mrad to 5 Mrad from the viewpoint of the curability and mechanical strength of the adhesive layer.

  The polyester film-laminated metal plate of the present invention is suitably used for cans such as beverage cans, food cans, miscellaneous cans, 5 gallon cans, and metal lids such as caps. It can also be applied to the outer surface of industrial equipment.

The present invention will be described more specifically with reference to examples. Hereinafter, “parts” and “%” mean “parts by mass” and “% by mass”, respectively.

Production Example 1 Production of Polyester Resin (A) In a reactor equipped with a thermometer, a stirrer, a heating device and a rectifying tower, 28.2 parts of ethylene glycol, 61.4 parts of neopentyl glycol, 1,4-butanediol 17.6 parts, 49.8 parts of terephthalic acid, 91.3 parts of isophthalic acid, and 21.9 parts of adipic acid are added. Further, a small amount of xylene for reflux is added, and the mixture is gradually heated to 250 ° C. and kept at the same temperature for 5 hours. The polyester resin (a) having a number average molecular weight of about 20,000, a weight average molecular weight of about 40,000, and a hydroxyl value of about 4 mgKOH / g was obtained.
Next, 100 parts of the polyester resin (a) and 67.3 parts of toluene are mixed to make a uniform solution, and then 1 part of hexamethylene diisocyanate is added with stirring to carry out a urethanation reaction. A urethane-modified polyester resin having a solid content of 60%. Polyester resin solution No. 1 was obtained. The obtained polyester resin solution No. The resin solid content of No. 1 was a weight average molecular weight of about 60,000 and a hydroxyl value of about 2 mgKOH / g. The glass transition temperature (see Note 2) was 50 ° C.

Comparative Production Example 1 Polyester resin No. Production of 2 In a four-necked flask equipped with a heating device, stirrer, thermometer, reflux condenser and water separator, 41.5 parts of terephthalic acid, 107.9 parts of isophthalic acid, 10 parts of succinic anhydride, ethylene glycol 15 .5 parts, neopentyl glycol 34.7 parts, 1,4-dimethylolcyclohexane 57.6 parts, trimethylolpropane 2.5 parts and an appropriate amount of a polycondensation catalyst were charged into an autoclave and heated to conduct an esterification reaction. A theoretical amount of condensed water was removed to obtain a polyester prepolymer.
Next, 24.5 parts of maleic anhydride was added to 1000 parts of the obtained polyester prepolymer, followed by heating and stirring to carry out an addition reaction, followed by cooling and mixing with a mixed solvent (toluene / methyl ethyl ketone = 50/50 (weight). Ratio)) and a polyester resin no. 2 was obtained. The obtained polyester resin solution No. 2 had a weight average molecular weight of about 3,100 and a hydroxyl value of about 23 mgKOH / g. The glass transition temperature (see Note 2) was 42 ° C.

Comparative Production Example 2 Polyester resin no. Production of 3 In a four-necked flask equipped with a heating device, stirrer, thermometer, reflux condenser and water separator, 41.5 parts of terephthalic acid, 83 parts of isophthalic acid, 25 parts of succinic anhydride, 15.5 ethylene glycol Parts, 1,4-butanediol 21 parts, neopentylglycol 3.2 parts, 1,4-dimethylolcyclohexane 28.8 parts, trimethylolpropane 2.5 parts and an appropriate amount of a polycondensation catalyst are charged into an autoclave and heated. Then, an esterification reaction was performed to remove a theoretical amount of condensed water to obtain a polyester prepolymer.
Next, 24.5 parts of maleic anhydride was added to 1000 parts of the obtained polyester prepolymer, followed by heating and stirring to carry out an addition reaction, followed by cooling and mixing with a mixed solvent (toluene / methyl ethyl ketone = 50/50 (weight). Ratio)) and a polyester resin no. 3 was obtained.
The obtained polyester resin solution No. 3 had a weight average molecular weight (see Note 1) of about 19,000 and a hydroxyl value of about 23 mgKOH / g. The glass transition temperature (see Note 2) was 6 ° C.

Production example 2 of acrylic resin (C) solution Production example 2
In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, thermostat and dropping pump, 60 parts of xylene were charged and heated to 125 ° C. while stirring. “Monomers and polymerization initiators shown in Table 1” Was added dropwise at a constant rate over 3 hours using a dropping pump. After the completion of the dropwise addition, the reaction was terminated by aging at the same temperature for 2 hours. 1 was obtained. The obtained acrylic resin solution No. The resin solid content of No. 1 had a weight average molecular weight (see Note 1) of about 9,000, a hydroxyl value of 78 mgKOH / g, and a glass transition temperature (see Note 2) of 70 ° C.

Production Examples 3 to 13
Except for making the mixture of a monomer and a polymerization initiator into the compounding composition shown in Table 1, it carried out similarly to manufacture example 2, and acrylic resin solution No.1. 3-No. 13 was obtained.

Comparative production examples of acrylic resin (C) solution Comparative production examples 3 to 14
Acrylic resin solution A to acrylic resin solution L were obtained in the same manner as in Production Example 2 except that the mixture of the monomer and the polymerization initiator was changed to the composition shown in Table 2.

Comparative Production Example 15
A reaction vessel equipped with a stirrer, thermometer, reflux condenser, thermostat and dropping pump was charged with 60 parts of xylene, heated to 125 ° C. with stirring, and the monomers and polymerization initiators shown in Table 2 were used. The mixture was added dropwise at a constant rate over 3 hours using a dropping pump. After completion of the dropwise addition, the reaction was terminated by aging at the same temperature for 2 hours to obtain an acrylic resin solution M having a resin solid content of 60%. The resin solid content of the obtained acrylic resin solution M had a weight average molecular weight of about 25,000, a hydroxyl value of 78 mgKOH / g, and a glass transition temperature of 70 ° C.

[Creation of adhesive-coated polyester film]
The following “adhesive” is applied to the corona discharge treated surface of the polyester film E5100 (made by Toyobo Co., Ltd., polyester film with a film thickness of 12 μm, single-sided corona discharge treatment) so that the dry film thickness becomes about 3 μm by gravure coating. Applied.
Next, the solution was passed through a 130 ° C. drying oven for 10 seconds to evaporate the solvent. Using this “adhesive-coated polyester film”, “tackiness (Note 14)” and “blocking property (Note 15)” were evaluated.

[Creation of PET laminated metal plate]
The above-mentioned “adhesive-coated polyester film” and canlite (manufactured by Nippon Steel Corporation), which is a tin plate having a thickness of 0.19 mm, are heat-laminated (roll temperature: 140 ° C., roll pressure: 5.0 kg / cm ² Conditions).
Next, an electron beam accelerator is used to irradiate the “polyester film of a laminated metal sheet subjected to heat lamination” with an electron beam (acceleration voltage of 270 keV, electron beam current of 50 mA, 4 Mrad condition), and an adhesive layer Was cured to obtain a “PET laminated metal plate”. Using this PET laminated metal plate, “film surface appearance (Note 16)”, “laminate strength (Note 17)”, and “retort resistance (Note 18)” were evaluated.

[Production of electron beam curable adhesive]
Example 1
Elitel UE3210 (Note 4) having a solid content of 60% was dispersed in 100 parts (solid content) by adding 10 parts (solid content) of Desmodur N3790BA (Note 6) and an appropriate amount of methyl ethyl ketone. The acrylic resin solution No. obtained in Production Example 2 was added to this dispersion. After adding 2.5 parts (solid content) of 1 and 3 parts (solid content) of Aronics M-8100 (Note 7), the mixture was sufficiently stirred. Next, 160 parts of JR-301 (Note 11), methyl ethyl ketone was further added and sufficiently stirred to adjust the solid content. 1 was obtained.
The adhesive No. 1 was used for the following test based on the creation of “test film and test plate”, and the results are also shown in the table.

Examples 2-25
Except that the blending composition is as shown in Table 3, it was carried out in the same manner as in Example 1, and the adhesive No. 2-No. 25 was obtained. The adhesive No. 2-No. 25, the adhesive-coated film and the PET-laminated metal plate prepared on the basis of the above-mentioned “Preparation of adhesive-coated film and PET-laminated metal plate” were subjected to the following test. 3 and Table 4.

  (Note 3) Elitel UE3200: manufactured by Unitika Ltd., trade name, hydroxyl value 6 mgKOH / g, acid value 1 mgKOH / g, weight average molecular weight 16,000, glass transition temperature 65 ° C., polyester resin (A)

  (Note 4) Elitel UE3210: manufactured by Unitika Ltd., trade name, hydroxyl value 4 mgKOH / g, acid value 1 mgKOH / g, weight average molecular weight 20,000, glass transition temperature 45 ° C., polyester resin (A)

  (Note 5) Duranate K6000: manufactured by Asahi Kasei Chemicals Corporation, trade name, active methylene blocked polyisocyanate, crosslinking agent (C)

  (Note 6) Death module N3790BA: manufactured by Sumika Bayer Urethane Co., Ltd., trade name, hexamethylene diisocyanate nurate.

(Note 7) Aronics M-8100: manufactured by Toagosei Co., Ltd., polymerizable unsaturated double bond concentration 6.7 mol / kg, number average molecular weight about 600, polymerizable unsaturated group-containing oligomer (B)
(Note 8) jER154: manufactured by Japan Epoxy Resin Co., Ltd., phenol novolac type epoxy resin, epoxy equivalent of 176 to 180

  (Note 9) Toray nylon SP-500: manufactured by Toray Industries, Inc., nylon powder, trade name, average particle diameter of about 5 μm, softening point of about 165 to 171 ° C., nylon fine particles

  (Note 10) Nonskid 5389: manufactured by Shamrock Chemicals Co., Ltd., trade name, polypropylene wax, average particle size of about 6.5 μm, softening point of about 147 ° C.

  (Note 11) JR-301: manufactured by Teika Co., Ltd., trade name, titanium white, colored pigment

  (Note 12) Iriodin 103W2: Merck, trade name, white mica

  (Note 13) Alpaste-7640NS: Toyo Aluminum Co., Ltd., trade name, aluminum paste

Comparative Examples 1-24
Except for changing the composition to the contents of Table 5 and Table 6, the same procedure as in Example 1 was carried out. 26-No. 49 was obtained.
The adhesive No. 26-No. 49, the adhesive-coated film and the PET-laminated metal plate prepared based on the above-mentioned “Preparation of adhesive-coated film and PET-laminated metal plate” were subjected to the following test. 5 and Table 6.

Test method (Note 14) Adhesiveness:
Two adhesive coated surfaces of the adhesive-coated polyester film (about 10 seconds after leaving the drying oven) obtained by evaporating the solvent are overlapped and pressed together by hand. The film was peeled off, and the peeled area with the larger peeled area of the adhesive from the polyester film surface of the two adhesive coated surfaces was evaluated.
A: No peeling is observed on the two adhesive-coated surfaces. O: Peeling is observed, and the larger peeling area is less than 10%.
Δ: The larger peeled area is 10% or more and less than 30%
X: The larger peeling area is 30% or more.

(Note 15) Blocking property:
The surface of the adhesive-coated polyester film obtained by evaporating the solvent is covered with another “polyester film E5100” so that the surface not subjected to corona discharge treatment faces the adhesive surface, and 10 kg / The sample was stored for 3 days in a room with a temperature of 25 ° C. and a humidity of 60% RH under a pressure of cm ² . This storage laminate film was cut to a width of 30 mm, and the peel strength (g / 30 mm) when the above-mentioned another PET film was peeled 180 ° from the dry paint film surface at a tensile speed of 500 mm / min was measured and evaluated according to the following criteria. .
A: Peel strength is less than 10 g / 30 mm
○: Peel strength is 10 g / 30 mm or more and less than 20 g / 30 mm Δ: Peel strength is 20 g / 30 mm or more and less than 50 g / 30 mm ×: Peel strength is 50 g / 30 mm or more.

(Note 16) Appearance of the film surface:
Using the storage laminate film prepared at the time of the blocking resistance test, another PET film that had been put on the dry coating surface was peeled off from the storage laminate film, and a tin plate having a thickness of 0.2 mm was formed on the dry coating surface that appeared. The “appearance of the PET laminate surface” of the PET laminate metal plate obtained by laminating the plate under the conditions of a lamination temperature of 160 ° C., a linear pressure of 50 kg, and a speed of 200 m / min was evaluated according to the following criteria.
A: No abnormality is observed on the PET laminate surface
◯: Slightly damaged skin is observed on the PET laminate surface
(Triangle | delta): Quite skin skin is recognized by the PET laminate surface. X: Skin skin is remarkably recognized by the PET laminate surface.

(Note 17) Laminate strength:
The PET laminated metal plate was cut to a width of 15 mm, and a peeling test between the PET film and the tin plate was conducted to evaluate the difficulty of peeling according to the following criteria.
○: PET film does not peel
Δ: A part of the PET film peels off, but the PET film breaks in the middle
X: The entire surface of the PET film peels off.

(Note 18) Retort resistance:
PET film when PET can be retorted in water vapor at 125 ° C for 30 minutes with a PET laminated metal plate pressed by a 200 end processing machine (can lid processing machine) with the tin plate side up The peeled state was evaluated according to the following criteria.
A: No peeling of the PET film is observed
A: A part of the PET film in the peripheral part is slightly peeled. Δ: A part of the PET film in the peripheral part is considerably peeled. X: The PET film in the peripheral part is peeled over the entire circumference.

  The adhesive excellent in blocking resistance used for manufacture of a polyester film bonded metal plate, and the polyester film bonded metal plate using this adhesive can be provided.

Claims (6)

For 100 parts by mass of the polyester resin (A) having a number average molecular weight of 5,000 to 60,000 and a glass transition temperature of 30 to 80 ° C., 0.1 to 30 parts by mass of the crosslinking agent (B), the following characteristics A metal can outer surface adhesive containing 0.3 to 10 parts by mass of acrylic resin (C).
Acrylic resin (C): at least one monomer (c1) 5 to 95 selected from isobornyl acrylate, isobornyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate, based on the total mass part of the constituent monomers By copolymerizing a monomer component consisting of 5 parts by mass, 5-30 parts by mass of a hydroxyl group-containing polymerizable unsaturated monomer (c2) and other polymerizable unsaturated monomer (c3),
An adhesive for metal can outer surface, which is a copolymer resin having a weight average molecular weight of 2,000 to 20,000, a hydroxyl value of 10 to 140 mgKOH / g, and a glass transition temperature of 30 to 80 ° C. The metal according to claim 1, comprising 0.1 to 30 parts by mass of a polymerizable unsaturated oligomer (D) having a polymerizable unsaturated double bond with respect to 100 parts by mass of the solid content of the polyester resin (A). Can outer surface adhesive. The adhesive for metal can outer surfaces of Claim 1 or 2 which contains a white pigment 200 mass parts or less with respect to 100 mass parts of polyester resins (A). The adhesive for metal can outer surfaces of any one of Claims 1-3 which contains 0.1-20 mass parts of luster pigments with respect to 100 mass parts of hydroxyl-containing polyester resin (A). The metal film outer surface adhesive according to any one of claims 1 to 4 is applied onto the polyester film and dried, and the polyester film having the adhesive layer is bonded to one or both sides of the metal plate. A method for producing a polyester film-laminated metal plate obtained by combining the adhesive layer surfaces and thermocompression bonding and curing the adhesive layer. A polyester film-laminated metal plate obtained by the production method of Production Example 5.