JPH11209731A - Adhesive composition for laminated can, laminated metal plate and metal can - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive composition excellent in adhesion to a metal surface of a can material, adhesive strength, processability and characteristics of retort compared to a conventional adhesive, and further excellent as the adhesive for a laminated can, and further to obtain a laminated metal plate and a metal can. SOLUTION: This adhesive composition contains (A) a (meth)acrylate-modified polyester obtained by modifying the terminal of a polyester resin having >5,000 number average molecular weight with an electric beam-hardenable (meth) acrylate-containing compound, and (B) a crosslinking agent capable of reacting with the component A within the range of the weight ratio of the component A to the component B regulated so as to be (100/0) to (25/75), and obtained by adding an organic solvent and/or a reactive diluent to the components A and B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive resin composition for laminated cans having excellent initial and cured adhesive strength, and further excellent workability and water resistance.

[0002]

2. Description of the Related Art Conventionally, protection of contents on the inner and outer surfaces of a beverage can,
Various paints are applied for the purpose of preventing metal corrosion, imparting aesthetic design, and the like. Since these paints are based on solvent-based or water-based resins, they have become can-making coating systems that use large energy for drying and curing. However, from the viewpoint of environmental protection in recent years, a can-coating system with solvent removal and energy saving has been studied, and a method of laminating a polyester film on a metal substrate for cans has been developed. For example, a method in which a polyester film is directly heat-sealed to a can base material (Japanese Patent Application Laid-Open No. Hei 3-212433), a method in which a polyester film and a can substrate are bonded via a thermosetting adhesive (Japanese Patent Application Laid-Open No. Hei 5-43859). ),and so on.

[0003]

The above-mentioned method of heat-sealing a polyester film to a can substrate requires strict process control because it is affected by the surface treatment state of the can substrate and the fusing temperature during lamination. Become. Furthermore, since it is necessary to print the appearance design after can manufacturing, the number of can manufacturing steps may increase. In addition, the method of bonding a polyester film and a can base material through a thermosetting adhesive requires a large amount of heat energy in order to obtain sufficient bonding strength because the bonding strength depends on the degree of curing and crosslinking. , The laminating speed must be reduced. In addition, the method using an electron beam-curable adhesive obtained by improving these methods (Japanese Patent Application Laid-Open Nos. 5-179205 and 7-310065) can save heat energy and improve lamination speed. In addition, there is a problem in that the adhesive layer after the electron beam irradiation cures and shrinks, resulting in poor adhesion to the polyester film immediately after lamination and insufficient adhesive strength to the can substrate.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above problems, and as a result, modified a polyester resin with a (meth) acrylate group-containing compound and blended it with a crosslinking agent. The inventors have found that various properties such as adhesion to a film, initial adhesion, adhesive strength, workability, and retort resistance can be highly satisfied by using the agent, and have led to the invention.

A (meth) acrylate-modified polyester (A) having a terminal modified with a (meth) acrylate group-containing compound capable of electron beam curing a polyester resin having a number average molecular weight exceeding 5,000 and a crosslinking agent (B) capable of reacting therewith An adhesive composition comprising the following formula (1) and adding an organic solvent and / or a reactive diluent thereto. (Meth) acrylate-modified polyester (A) whose terminal is modified with a (meth) acrylate group-containing compound capable of electron beam curing a polyester resin in which aromatic dicarboxylic acid is 50 to 100 mol% of all acid components, and reacts with this An adhesive composition comprising a crosslinker (B) that can be used in the range of the following formula (1), and adding an organic solvent and / or a reactive diluent thereto. (A) / (B) = 100/0 to 25/75 (weight ratio) − (1)

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The acid component of the polyester resin of the present invention includes aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid. 3, aliphatic dicarboxylic acids such as dodecandioic acid, maleic acid and fumaric acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, tetrahydrophthalic acid and 1,4-cyclohexanedicarboxylic acid; trimellitic acid; Or higher polyvalent carboxylic acids, and among them, preferred are terephthalic acid, isophthalic acid, adipic acid, sebacic acid, trimellitic acid, and the like, and one or more of these are optionally used. Can be selected and used.
In addition, the aromatic dicarboxylic acid is preferably 50 to 100 mol%, more preferably 70 to 100 mol%, and still more preferably 80 mol% in all the acid components of the polyester resin.
１００100 mol%. When the aromatic carboxylic acid is less than 50 mol% in all the acid components of the polyester resin, physical properties such as adhesion, retort resistance, and water resistance are reduced,
Undesirably, the pressure at the time of lamination causes the adhesive layer to deviate from the film or the can base, causes blocking after winding the film, or lowers the retort resistance of the processed portion.

The alcohol component of the polyester resin used in the present invention is ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 2,2-diethyl-1,3-propane. Diol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, 2-n-hexyl-
2-ethyl-1,3-propanediol, 2,2-di-
n-hexyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol , 3-methyl-pentanediol, 3-ethyl-1,5-pentanediol, 3-propyl-1,5-pentanediol, 3-methyl-1,6-hexanediol, 4-methyl-1,7
-Heptanediol, 1,9-nonanediol, 1-methyl-1,8-octanediol, 4-methyl-1,8
Aliphatic polyhydric alcohols such as octanediol, 4-propyl-1,8-octanediol, diethylene glycol, triethylene glycol, glycerin, trimethylolethane, trimethylolpropane, mannitol, sorbitol, pentaerythritol, α-methylglycoside, 1,4-cyclohexanedimethanol, 1,
3-cyclohexane dimethanol, 1,2-cyclohexane dimethanol, tricyclodecane dimethanol,
Alicyclic polyhydric alcohols such as water-added bisphenols, alkylene oxide adducts of bisphenol A, alkylene oxide adducts of bisphenol S, alkylene oxide adducts of bisphenol F, aromatic polyhydric alcohols such as xylene glycol, etc., trimethylol Propane, pentaerythritol, trihydric or higher polyhydric alcohols such as glycerin and the like are preferable, and among these, preferred are ethylene glycol, neopentyl glycol,
1,4-butanediol, 1,5-pentanediol,
These are 1,6-hexanediol and 1,4-cyclohexanedimethanol, and one or more of these can be selected and used.

The number average molecular weight of the polyester resin used in the present invention must exceed 5,000. It is preferably at least 7000, more preferably at least 10,000. If the number average molecular weight is 5,000 or less, adhesion, processability, and retort resistance are poor, and further, blocking occurs after winding the film, which is not preferable. Especially,
In the case of 3,000 or less, since the polyester block unit is short, these physical properties are greatly reduced.

The polyester resin used in the present invention has an acid value
Is 40 to 400 eq / 10⁶ g,
More preferably, 60 to 250 eq / 10⁶ g, even better
Preferably 70 to 200 eq / 10⁶ g. Po
Since the ester resin has an acid value, higher
High degree of adhesion can be obtained and used as a crosslinking agent
Improves reactivity with possible epoxy resin and amino resin
Bridge points can be dense and high adhesive strength can be obtained. Poly
The acid value of the ester is 40 eq / 10⁶ less than g
In some cases, the effect of adhesion to a metal surface may not be obtained.
00eq / 10 ⁶ If the acid value exceeds g, processability and resistance to
The tolt is reduced.

As a method for introducing an acid value into the polyester resin, a polycarboxylic acid is charged in excess or almost the same amount as the polyhydric alcohol to carry out polycondensation to leave a carboxyl group at a molecular terminal, or after completion of polymerization of the polyester resin. A carboxyl group can be imparted by acid-modifying (ring-opening addition) the terminal hydroxyl group with a polycarboxylic anhydride or the like, but the latter method facilitates the addition of the acid value and the amount of the terminal hydroxyl group. It is preferable because it can be controlled to Phthalic anhydride as polyhydric carboxylic anhydride used for acid modification,
Trimellitic anhydride, pyromellitic anhydride, benzophenone anhydride tetracarboxylic acid, succinic anhydride, maleic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride and the like, among which particularly preferred are phthalic anhydride, Trimellitic anhydride can be used, and one or more kinds can be arbitrarily selected and used.

The polyester resin used in the present invention preferably has a glass transition temperature of 0 ° C. or higher, more preferably in the range of 10 to 50 ° C. When the glass transition temperature of the polyester is less than 0 ° C., the adhesive layer and the film, or the displacement between the can substrate occurs due to pressing during lamination, and the curing shrinkage of the adhesive layer at the time of reaction curing increases, so that the film and the In some cases, or blocking may occur after winding the film. When the glass transition temperature exceeds 50 ° C., the adhesiveness is reduced,
The retort resistance of the processed portion is reduced, which is not preferable.

The adhesive composition of the present invention uses a (meth) acrylate-modified polyester (A) whose terminal has been modified with a (meth) acrylate group-containing compound capable of electron beam curing the polyester resin. Examples of the (meth) acrylate group-containing compound include monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and allyl alcohol, and urethane oligomers. Oligomers such as urethane (meth) acrylate oligomers having a (meth) acrylate group introduced at the end and polyester (meth) acrylate oligomers having a (meth) acrylate group introduced at the end of the polyester oligomer, are easily modified. It is preferable to use monomers from the viewpoint of the amount of the (meth) acrylate group that can be modified and the like. Examples of the modification method include a method in which a terminal hydroxyl group of a polyester resin is once prepolymerized with a polyvalent isocyanate compound and added to a hydroxyl group of a (meth) acrylate group-containing compound,
A method of isocyanating a hydroxyl group of a (meth) acrylate group-containing compound with a polyvalent isocyanate compound and adding the isocyanate to a hydroxyl group of a polyester, a polyester resin, a (meth) acrylate group-containing compound, and if necessary, a polyhydric alcohol (chain extender A) a method of adding a polyvalent isocyanate compound to a mixed system and reacting the mixture by esterifying a terminal hydroxyl group of the polyester with an unsaturated aliphatic polycarboxylic acid such as (meth) acrylic acid, maleic acid, fumaric acid or the like. There is a method obtained by esterification of the terminal carboxyl group of the polyester with the above-mentioned (meth) acrylate having a hydroxyl group in the molecule. However, the method is not limited to these methods, and the method of functionalizing the (meth) acrylate group-containing compound Modification by other methods is possible depending on the group A.

The polyvalent isocyanate compound used for the modification includes tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, Examples include phenylmethane triisocyanate, tris (isocyanatephenyl) thioisocyanate, and addition derivatives obtained by reacting the above polyisocyanate with a polyhydric alcohol, and preferably include 4,4′-diphenylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. One or two or more of these can be selected and used.

Examples of polyhydric alcohols (chain extenders) include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, 2-n-hexyl-2-ethyl-1,3-propanediol , 2,2-di-n-hexyl-1,3-
Propanediol, 2-ethyl-2-isobutyl-1,
3-propanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-pentanediol, 3-ethyl-1,5-pentanediol, 3- Propyl-1,5
-Pentanediol, 3-methyl-1,6-hexanediol, 4-methyl-1,7-heptanediol, 1,
9-nonanediol, 1-methyl-1,8-octanediol, 4-methyl-1,8-octanediol, 4-
Propyl-1,8-octanediol, diethylene glycol, triethylene glycol, glycerin, trimethylolethane, trimethylolpropane, mannitol, sorbitol, pentaerythritol, an alkylene oxide adduct of bisphenol A, an alkylene oxide adduct of bisphenol S, bisphenol F Alkylene oxide adducts and glycols such as xylene glycol, and one or two or more thereof can be selected and used.

The adhesive composition of the present invention can contain (meth) acrylate-modified polyester (A) and a crosslinking agent (B) which can react therewith in the range of the following formula. If the weight ratio of the cross-linking agent (B) exceeds 75 parts by weight, the processability is reduced. (A) / (B) = 100/0 to 25/75 (weight ratio)-(1) Preferably, (A) / (B) is 100/0 to 75 /
25, and sufficiently good performance can be obtained without blending the crosslinking agent (B), but more preferably 99.5 / 0.5.
5 to 80/20 (weight ratio), more preferably 99/1 to
90/10 (weight ratio).

The crosslinking agent (B) usable in the adhesive composition of the present invention is mainly capable of reacting with the hydroxyl group or carboxyl group contained in the (meth) acrylate-modified polyester (A). , Isocyanate compounds, epoxy compounds and the like.

Examples of the amino resin include formaldehyde adducts such as urea, melamine, urea, and benzoguanamine, and alkyl ether compounds of alcohols having 1 to 6 carbon atoms. Specific examples include methoxylated methylol urea, methoxylated methylol-N, N-ethylene urea, methoxylated methylol dicyandiamide, methoxylated methylol melamine, methoxylated methylol benzoguanamine, butoxylated methylol melamine, butoxylated methylol benzoguanamine, and the like. Each can be used alone or in combination.

Further, as the isocyanate compound, there are aromatic, aliphatic and alicyclic diisocyanates, and polyisocyanates having a valency of 3 or more. Either a low molecular compound or a high molecular compound may be used. For example, tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate,
Hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, or trimers of these isocyanate compounds, and excess amounts of these isocyanate compounds and, for example, ethylene glycol, propylene glycol, trimethylolpropane, glycerin Terminal isocyanate obtained by reacting with sorbitol, ethylenediamine, monoethanolamine, diethanolamine, low molecular weight active hydrogen compounds such as triethanolamine or various high molecular weight hydrogen compounds such as polyester polyols, polyether polyols and polyamides Group-containing compounds. These can be used alone or in combination.

When a pot life is required, a blocked isocyanate is preferably used as the isocyanate compound. Examples of the isocyanate blocking agent include phenols such as phenol, thiophenol, methylthiophenol, cresol, xylenol, resorcinol, nitrophenol, and chlorophenol;
Oximes such as acetoxime, methyl ethyl ketoxime and cyclohexanone oxime, alcohols such as methanol, ethanol, propanol and butanol, ethylene chlorohydrin, 1,3-dichloro-2-
Halogen-substituted alcohols such as propanol, tertiary alcohols such as t-butanol and t-pentanol;
lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, β-propyllactam, and other active methylenes such as aromatic amines, imides, acetylacetone, acetoacetate, and malonic acid ethyl ester. Compounds, mercaptans, imines, ureas, diaryl compounds and sodium bisulfite are also included. The blocked isocyanate is obtained by reacting the above-mentioned isocyanate compound and a blocking agent by a conventionally known method, and can be used alone or in combination.

Further, as the epoxy compound, for example, diglycidyl ether of bisphenol A and its oligomer, diglycidyl orthophthalate, diglycidyl isophthalate, diglycidyl terephthalate, diglycidyl p-oxybenzoate,
Diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, diglycidyl succinate, diglycidyl adipate,
Sebacic acid diglycidyl ester, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and polyalkylene glycol diglycidyl ethers, trimellitic acid Triglycidyl ester, triglycidyl isocyanurate, 1,4-glycidyloxybenzene, diglycidyl propylene urea, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, glycerol alkylene oxide Triglycidyl ether of an adduct and the like can be mentioned. These can be used alone or in combination. Among these, an isocyanate compound is most preferable in terms of adhesiveness, processability, and curability.

It is also possible to add a polymer component (C) other than the (meth) acrylate-modified polyester (A) to the adhesive resin composition of the present invention. Modified polyester (A)
When the total amount of the polymer component (C) and the other components is 100 parts by weight, the amount is preferably 60 parts by weight or less.
Further, it is preferably at most 40 parts by weight, most preferably at most 20 parts by weight. As the polymer component (C), polyester resin, polyamide resin,
Polyimide resin, polycarbonate resin, polyurethane resin, cellulose resin, natural and synthetic rubber resin, polyolefin resin, polystyrene resin, acrylic resin, vinyl acetate resin, vinyl chloride resin, diene resin, vinyl group-containing monomer And known resins such as a resin obtained by copolymerizing In addition, these resins may contain radically crosslinkable groups, except for the polyester resin, may be modified to be radically crosslinkable, and may undergo a curing reaction with the crosslinking agent (B). It may be denatured. The polyester resin contained as the other polymer component (C) may contain a radically polymerizable component as a copolymerization component, or may be modified so as to undergo a curing reaction with the crosslinking agent (B). Absent.

Further, a (meth) acrylate oligomer can be added to the adhesive composition of the present invention, if necessary. The (meth) acrylate oligomer is not particularly limited. For example, a number average molecular weight of 5 obtained by polycondensing a polyhydric alcohol with a polyhydric carboxylic acid in which the aromatic dicarboxylic acid in all the acid components is less than 50 mol% is 5 Compounds obtained by esterification of terminal hydroxyl groups of a low molecular weight polyester (polyester oligomer) having a molecular weight of 2,000 or less with unsaturated aliphatic polycarboxylic acids such as (meth) acrylic acid, maleic acid and fumaric acid, or all acid components A compound obtained by esterifying the terminal carboxyl group of a polyester oligomer having an aromatic dicarboxylic acid content of less than 50 mol% with the above-mentioned (meth) acrylate having a hydroxyl group in the molecule, and furthermore the aromatic component in the total acid component Polyester oligomer having less than 50 mol% of aliphatic dicarboxylic acid and hydroxyl group To (meth) polyvalent isocyanate compound described above with an acrylate, optionally 2
There is a urethane (meth) acrylate compound obtained by reacting with a polyhydric alcohol having a valency or higher (chain extender). Polyhydric carboxylic acids, polyhydric alcohols used for polyester oligomers, polyvalent isocyanate compounds used for urethane (meth) acrylate, and chain extenders include the above-mentioned polyester resin raw materials and polyvalent isocyanate compounds. One, or two or more, can be selected from and used. In addition, a polyether diol whose terminal is modified with (meth) acrylate may be used.

The adhesive composition of the present invention is used in a state of being dissolved with a known organic solvent and / or a reactive diluent in order to obtain coating workability. The organic solvent to be used is selected from toluene, xylene, solvesso, ethyl acetate, butyl acetate, methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, isophorone, methoxypropylene glycol acetate and the like in consideration of solubility, reactivity, evaporation rate and the like. . As the diluent, a reactive diluent having a double bond can be used in addition to the organic solvent. Examples of the reactive diluent include 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, and cyclohexyl (meth). ) Acrylate, butoxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, glycidyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, isobonyl (meth) acrylate, Ethylene oxide-modified phosphoric acid (meth) acrylate, N-methylvinylpyrrolidone, caprolactone-modified tetrahydrofurfuryl (meth) acrylate, (meth) acryloxyethyl succine , 2-hydroxy-3-phenoxypropyl (meth) monoacrylate compounds such acrylate, ethylene glycol di (meth)
Acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate hydroxypivalate , Dicyclopentanyldi (meth)
Acrylate, bisphenol A di (meth) acrylate, ethylene oxide-modified di (meth) acrylate phosphate, ethylene oxide-modified bisphenol A di (meth) acrylate, polyethylene glycol di (meth)
Diacrylate compounds such as acrylate, triacrylate compounds such as trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide-modified trimethylolpropane triacrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra Examples thereof include tetraacrylate compounds such as (meth) acrylate and propionic acid-modified dipentaerythritol tetra (meth) acrylate.

The adhesive composition of the present invention may contain, if necessary, known inorganic pigments such as titanium oxide, silica, calcium carbonate, magnesium carbonate, and aluminum oxide, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, phosphoric acid, Organotin compounds, organophosphorus compounds, curing catalysts such as tertiary amines, antistatic agents, surface smoothing agents, defoamers, dispersants,
Known additives such as a stabilizer can be blended.

The resin film to which the adhesive composition of the present invention is applied is not particularly limited as long as it is a resin film that can be processed into a film. For example, a vinyl chloride film, a vinylidene chloride film, a polyethylene film, Polypropylene film, polyester film,
Polyamide film, and the like. Among them, a polyester film is particularly preferable. As the polyester film, a film in which 75% or more of the repeating unit usually comprises an ethylene terephthalate unit is preferably used. Examples of the repeating unit other than the ethylene terephthalate unit include ester units containing an acid and an alcohol, which are listed for the polyester of the above-mentioned adhesive composition of the present invention. The resin film is usually subjected to a surface treatment such as a corona discharge treatment in order to improve the adhesiveness with the adhesive. Further, in order to improve the adhesiveness, a film in which an easy adhesion layer is separately provided on a resin film can be used.

The metal sheet used is a hot-drawn steel sheet, a cold-rolled steel sheet, a hot-dip galvanized steel sheet, a zinc alloy-coated steel sheet, an electro-galvanized steel sheet, a zinc alloy-plated steel sheet, tinplate, tin-free steel, an aluminum-plated steel sheet, a turn-plated steel sheet And metal plates such as nickel-plated steel plates, other alloy-plated steel plates, stainless steel, and aluminum steel plates. Those subjected to various surface treatments and primer treatments as necessary are used.

The adhesive composition of the present invention can be applied to any one of the above-mentioned polyester films and metal plates by a usual coating method such as a roll coater, a knife coater, gravure printing, spray coating or the like, to a level of about 1 to ²⁰ g / m ^2. After the coating is performed as described above and the solvent is volatilized as necessary, the bonding surfaces are aligned and bonded under heating to obtain a laminated metal plate.

The laminated metal plate obtained by the above method is irradiated with an electron beam from the polyester film side. Cockcroft type, Cockcroft-Walton type, Van de Graaf type, Strong vibration type, Transformer type, Insulated core transformer type, Dynamitron type, Linear filament type , Area beam type, high frequency type and the like.

The electron beam energy required to cure the adhesive composition of the present invention is suitably in the range of 100 to 300 keV, preferably 150 to 200 keV. The irradiation dose is 0.2 to 15 Mrad, preferably 1 to 5 Mrad
Is appropriate. When the irradiation dose is less than 0.2 Mrad, the curing of the adhesive layer becomes insufficient, and the adhesive strength cannot be obtained. When the irradiation dose exceeds 15 Mrad, the mechanical strength of the polyester film is reduced.

After the coated metal sheet thus obtained is cut out, it can be processed into a can, a lid, a cap or the like by a known method.

[0031]

The present invention will be specifically described below with reference to examples. In the examples, “part (s)” means “part (s) by weight”. Each measurement evaluation item followed the following method. (1) Measurement of Resin Composition The molar ratio of an acid component and an alcohol component was determined by nuclear magnetic resonance spectroscopy and analysis by gas chromatography after alcoholysis. (2) Measurement of Glass Transition Temperature The glass transition temperature was measured at a heating rate of 20 ° C./min using a differential scanning calorimeter (DSC). (3) Measurement of acid value 0.2 g of the resin was dissolved in 20 ml of chloroform.
Titration was performed with a 1N KOH ethanol solution to determine an equivalent weight (eq / 10 ⁶ g) per 10 ⁶ g of the resin. (4) Measurement of number average molecular weight Using a gel permeation chromatograph manufactured by Waters Co., Ltd., Model 150-C, measuring solvent tetrahydrofuran, measuring temperature 30 ° C., flow rate 1 ml / min, and Shodex KF802, 804, 806 as columns ( (Manufactured by Showa Denko KK) in terms of polystyrene.

Synthesis Example (a) Polyester resin 109 parts of dimethyl terephthalate, 218 parts of dimethyl isophthalate, 202 parts of ethylene glycol, 175 parts of neopentyl glycol, titanium tetrabutoxide 0.1 part
15 parts were charged into a 2 L four-necked flask, and the temperature was gradually raised to 230 ° C. over 4 hours, and a transesterification reaction was carried out while distilling methanol out of the system. Then this is 1
After cooling to 90 ° C. and adding 114 parts of sebacic acid, the temperature was raised again to 230 ° C. over 2 hours, and an esterification reaction was carried out while distilling out water outside the system. Subsequently, this was subjected to initial polymerization under reduced pressure to 10 mmHg over 30 minutes, the temperature was increased to 245 ° C., and late polymerization was further performed at 1 mmHg or less for 45 minutes. After the polymerization, 230 ° C under a nitrogen stream
Then, 4.3 parts of trimellitic anhydride was charged, and 30 parts of
A partial ring-opening addition reaction was performed to obtain a polyester resin (a) of the present invention. The obtained resin was dissolved in toluene and used as a 50% solids solution. Table 1 shows the resin characteristic values.

Synthetic Examples (b) to (c) Polyester Resins In the same manner as in Synthetic Example (a), polyester resins (b) to (c) of the present invention having resin compositions shown in Table 1 were synthesized.

[0034]

[Table 1]

Synthesis Examples (d) to (h) Polyester resin Synthesis was performed in the same manner as in Synthesis Example (a) except that addition was not performed after trimellitic acid. (G) and (h) are comparative polyester resins. Tables 1 and 2 show the resin properties.

[0036]

[Table 2]

Synthesis Example (i) Isocyanate acrylate compound for modification 100 parts of 2-hydroxyethyl acrylate and 245 parts of toluene were dissolved and stirred in a 1 L four-necked flask. 145 parts of hexamethylene diisocyanate was added thereto,
After homogenization, 1 part of dibutyltin dilaurate was added, the temperature was gradually raised to 80 ° C., and the reaction was carried out for 4 hours to obtain a solid content of about 50%.
Isocyanate acrylate compound (i) was obtained.

Synthesis Example (j) Isocyanate methacrylate compound for modification 100 parts of 2-hydroxyethyl methacrylate and 275 parts of toluene were dissolved in a 1 L four-necked flask and stirred. 175 parts of isophorone diisocyanate was added thereto, and after homogenization, 1 part of dibutyltin dilaurate was added, the temperature was gradually raised to 80 ° C., and the mixture was reacted for 6 hours, and the isocyanate methacrylate compound (j) having a solid content of about 50% was obtained.
I got

Modification Example (A) Acrylate-modified polyester A toluene solution of a polyester resin having a solid content of 50% (a)
100 parts were charged into a 1 L four-necked flask, and dissolved and stirred at 80 ° C. 7 parts of a separately prepared isocyanate acrylate compound solution (g) was added thereto, followed by stirring at 80 ° C. for 4 hours to obtain an acrylate-modified polyester resin solution (A) of the present invention having a solid content of about 50%. Table 3 shows the denaturation ratio.

Modified Examples (B) to (H) (Meth) acrylate-modified polyester Resin solutions (B) to (E) of the present invention were obtained in the same manner as in Production Example (A).
(G) and (H) are comparative modified examples. Table 3 shows the denaturation ratio.

[0041]

[Table 3]

Comparative Modification Example (I) Acrylic-modified polyester 67 parts of trimethylolpropane, 150 parts of triethylene glycol, 60 parts of 1,6-hexanediol, 220 parts of adipic acid, and 0.3 parts of dibutyltin oxide were added to 2 L of 4 parts.
The mixture was charged in a single-necked flask, gradually heated to 230 ° C. over 4 hours, and esterified while removing distilled water outside the system to obtain a polyester resin having a number average molecular weight of 2,000.
This was cooled to 60 ° C., and 300 parts of toluene, 150 parts of acrylic acid, and 0.05 part of hydroquinone were added, and 100 parts were added.
The esterification reaction was carried out at 4 ° C. for 4 hours. After completion of the reaction, the solvent and unreacted acrylic acid were removed by distillation, and 230 parts of methyl ethyl ketone and 230 parts of toluene were added again to obtain an acrylic-modified polyester (I) having a solid content of about 50%.

Comparative Synthesis Example (J) Methacryl-modified polyurethane aliphatic polyester oligomer OD-X-2044 (molecular weight: 2,000, manufactured by Dainippon Ink and Chemicals, Inc.)
00 parts, 1,6-hexanediol 40 parts, toluene 1
50 parts are charged into a 1 L four-necked flask, heated to 80 ° C., dissolved and stirred. Cool it down to 60 ° C,
After adding 180 parts of isophorone diisocyanate and 1.9 parts of dibutyltin dilaurate, the temperature was raised to 90 ° C., and the mixture was stirred for 2 hours to obtain a prepolymer having a number average molecular weight of 2500. To this prepolymer, 140 parts of toluene and 110 parts of 2-hydroxy-ethyl methacrylate were added, and 9 parts were further added.
The mixture was stirred at 0 ° C. for 2 hours to obtain a methacryl-modified polyurethane (J) having a solid content of about 60%.

Formulation Example (1) Electron beam-curable adhesive Coronate-HX (manufactured by Nippon Polyurethane Industry Co., Ltd.) was added to 196 parts of an acrylic modified polyester resin solution (A).
And 0.1 part of dibutyltin dilaurate to prepare Example Adhesive (1) having a solid content of about 50%. Table 4 shows the composition.

Formulation Example (2) Electron beam-curable adhesive Acrylic-modified polyester resin solution (A)
After dilution with 200 parts of EK, 200 parts of titanium oxide JR-300 (manufactured by Teikoku Kako Co., Ltd.) was added thereto, and the mixture was dispersed with a paint shaker for 5 hours. This is Coronate HX
(Nippon Polyurethane Industry Co., Ltd.) 2 parts and dibutyltin dilaurate 0.1 part were blended to prepare an example adhesive (2) having a solid content of about 50%. Table 4 shows the composition.

Formulation Examples (3) to (7) Electron Beam Curable Adhesives The adhesives of Examples (3) to (7) were prepared in the same manner as the adhesive of Example (1) or (2). did. Table 4 shows the composition
Shown in

Comparative Examples (1) to (7) Electron Beam Curable Adhesives Adhesives (1) to (7) of comparative examples were prepared in the same manner as in Example (1) or (2). Table 5 shows the composition.

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[Table 4]

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[Table 5]

Preparation of Laminated Metal Sheet The adhesives of Examples and Comparative Examples blended by the above-mentioned method on a corona discharge treated PET film (12 μm thick) were applied with a bar coater to a thickness of 3 to 5 μm. ° C
The solvent was dried for 20 seconds. Subsequently, this adhesive-coated film was bonded to chin-free steel (0.3 mm thick), and the roll temperature was 180 ° C. and the roll pressure was 5.0 kg / cm ^2.
Under the conditions described above. Next, using an electron beam irradiation device, an electron beam was irradiated from the PET film surface by 4 Mr.
Irradiation was performed to cure the adhesive to obtain a laminated metal plate. Various performances were evaluated using the obtained metal plate.

Evaluation Method The following evaluations were performed using the adhesives of the examples and the comparative examples, and using the laminated metal plates obtained by the above method. The results are shown in Tables 4 and 5. (1) Adhesive strength 180 ° C peeling: according to JIS K-6744. (2) DuPont impact test: A 1 mm square cut (100 squares) is cut into the film side of the laminated metal plate with a cutter. 1/2 inch x 300g x from the back
An impact is applied at a height of 30 cm, and the number of squares of the film remaining on the metal plate is counted. (3) Retort resistance: A 1 mm square cut (100 squares) is cut into the film side of the laminated metal plate with a cutter. 5m from Eriksen tester from the back of this center
m. After leaving this sample in pressurized steam at 125 ° C. for 30 minutes, cellophane tape peeling is performed, and the number of squares of the film remaining on the metal plate is counted. (4) Heat resistance: 5c width on the film side of the laminated metal plate
An X-shaped cut of m is made with a cutter, and the center thereof is pushed in with an Erichsen tester by 5 mm. This sample is left in an atmosphere of 200 ° C. for 5 minutes, and it is visually observed whether or not peeling occurs due to shrinkage of the film. ○: No peeling △: Partial peeling ×: Remarkable peeling

As can be seen from Tables 4 and 5, the electron beam-curable adhesive using the (meth) acryl-modified polyester of the present invention is superior in electron beam curability to the conventional technology, and has various properties including adhesiveness. It can be seen that it has outstanding performance.

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The adhesive composition of the present invention comprises a (meth) acrylate-modified polyester obtained by modifying a polyester resin with a (meth) acrylate group-containing compound and a cross-linking agent as main components, so that a PET film in a laminate can can be obtained. The adhesiveness of the can base material is superior to conventional adhesives in adhesion to metal surfaces as can materials, adhesive strength, workability, and retortability, and is suitable as an adhesive for laminated cans.

Claims (4)

[Claims] (1) A (meth) acrylate-modified polyester (A) whose terminal has been modified with a (meth) acrylate group-containing compound capable of electron beam curing a polyester resin having a number average molecular weight of more than 5000, and a crosslinking agent capable of reacting therewith. An adhesive composition comprising (B) in the range of the following formula (1), and adding an organic solvent and / or a reactive diluent thereto. (A) / (B) = 100/0 to 25/75 (weight ratio) − (1) 2. The polyester resin having an acid value of 40 to 400.
The adhesive composition according to claim 1, wherein the composition has an eq / 10 ⁶ g and a glass transition temperature of 0 ° C or more. 3. A laminated metal plate, wherein an adhesive layer using the adhesive composition according to claim 1 or 2 is laminated between a metal plate and a resin film. 4. A metal can using the laminated metal plate according to claim 3.