JPH0362146B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a metal-polypropylene film laminate made by laminating a polypropylene film with good corrosion resistance to a metal plate, and its main purpose is to provide excellent adhesive workability and corrosion resistance. An object of the present invention is to provide a resin-coated metal plate having the following properties. (Prior Art) Conventionally, a metal-polyolefin laminate in which a polyolefin in film such as polyethylene or polypropylene is formed on a metal plate via an adhesive layer such as an adhesive or a modified olefin composition has been manufactured based on the characteristics of the polyolefin in film, such as normal chemical resistance,
Taking advantage of its properties such as solvent resistance and heat resistance, it is mainly applied to container materials and indoor and outdoor building materials. Several methods have been proposed for producing this metal-polyolefin film laminate. For example, a method of bonding by thermocompression onto a metal substrate containing a carboxyl group-modified polyolefin, and a method of bonding a three-layer structure of an epoxy resin primer, a modified polyolefin, and an olefin film on a metal surface (Japanese Patent Laid-Open No. 117642/1983)
(Japanese Patent Application Laid-open No. 133242/1989, Japanese Patent Application Laid-open No. 133242/1983), a method of bonding a polyolefin film to a metal substrate using an adhesive prepared by dispersing carboxyl-modified polyolefin powder in an epoxy resin containing a curing agent. Examples include a method using an adhesive prepared by reacting a saturated hydrocarbon having a carboxyl group with an epoxy resin (Japanese Patent Application Laid-open No. 124812/1985). The metal-polyolefin film laminate produced by these methods has sufficient adhesive strength and exhibits good corrosion resistance and durability against common chemicals and solvents. (Problem to be solved by the invention) However, ordinary polyolefin films such as polyethylene and polypropylene have the property of relatively quickly absorbing and permeating lower fatty acids such as acetic acid and butyric acid, and chlorinated solvents such as carbon tetrachloride. It also has a relatively high oxygen gas permeability, so if the polyolefin side is exposed to substances containing these for a long time, depending on the conditions, these acids and oxygen will permeate through the film, and in a very short period of time it will become metal. It may reach surfaces and cause corrosion. Such a phenomenon cannot be prevented even by the above-mentioned prior art method of using an epoxy resin as a primer or dispersing carboxyl group polyolefin powder in an epoxy resin. Therefore, for example, when a metal-polyolefin laminate is used as a container material, this drawback significantly limits its range of application as a container. (Means for Solving the Problems) As a result of extensive studies in order to solve the characteristic problem of permeation of corrosive substances such as organic acids into the film in metal-polypropylene laminates, the present inventor found that epoxy ester In adhesive compositions made of resin, resol type phenolic resin, and carboxyl group-modified polypropylene, by imparting flexibility to the epoxy ester resin and keeping the acid value of the resulting resin low, corrosion that penetrates the film layer can be prevented. We have discovered that the adhesive layer exhibits a powerful barrier ability against harmful substances. As will be shown in the Examples below, by doing so, the corrosion resistance of the entire coating layer is significantly improved without impairing process adhesion. That is, the present invention provides a laminate in which polypropylene films are laminated via an adhesive layer formed on a metal base material, in which the adhesive layer contains 100 parts by weight of a bisphenol A type epoxy resin and 1 to 1 to 1 saturated dibasic acid. Solvent-soluble resin 100 consisting of 90-40% by weight of an epoxy ester resin composition (A) modified with 20 parts by weight and having an acid value of 10 or less, and 10-60% by weight of resol type phenolic resin (B) The metal-polypropylene film laminate is a bake-hardened coating containing 3 to 100 parts by weight of dispersed carboxyl group-modified polypropylene (C). The bisphenol A type epoxy resin in the present invention refers to epichlorohydrin and 2,2-bis(4-
It is obtained by the reaction of hydroxyphenyl)propane, and the average molecular weight calculated from the epoxy equivalent is
Although those having an average molecular weight of 800 or more can be used, those having an average molecular weight of 2,000 to 4,000 are preferable. Composition (A) of epoxy ester resin in the present invention
is a resin composition made by partially modifying a bisphenol A type epoxy resin with a fatty acid, such as a resin epoxy esterified with a saturated dibasic acid such as adipic acid, suberic acid, azelaic acid, or sebacic acid. It is. The method for epoxy esterification is 1 to 1 to 100 parts by weight of epoxy resin.
Add 20 parts by weight of fatty acids and heat at a temperature of 100 to 200℃.
Allow to react for ~8 hours. At this time, the acid value of the resin produced by esterification has a strong influence on the barrier ability of the adhesive composition finally prepared against lower fatty acids that penetrate, for example, a polypropylene film. In the present invention, when the acid value of the epoxy ester is set to 10 or less, preferably 3 or less, remarkable effects are obtained. The resol type phenolic resin (B) in the present invention is obtained by a known method of addition-condensing formaldehyde to phenols under a catalyst, and also includes those modified with phenolic hydroxyl groups or alcoholic hydroxyl groups. In addition, the phenols include phenol, o-cresol, m-cresol,
p-cresol, p-tert-butylphenol,
p-nonylphenol, p-octylphenol, p-phenylphenol, methylphenol, ethylphenol, propylphenol, isopropylphenol, butylphenol, p-
tert-amylphenol, 4,4'-sec-butylidenephenol, p-cyclohexylphenol,
4,4'-isopropylidene-diphenol (bisphenol A), xylenol, phenyl-o-
Cresol etc. may be used alone or in combination of two or more, and as a catalyst, organic amines such as ammonia, ethylamine, butylamine, diethanolamine, etc.
Basic compounds such as sodium hydroxide, magnesium hydroxide, calcium hydroxide, and barium hydroxide are used, and as formaldehyde, a 37% aqueous solution or a 40% butanol solution is used. The solvent-soluble resin according to the present invention is composed of an epoxy ester resin composition (A) of 90 to 40% by weight and a resol type phenolic resin (B) of 10 to 60% by weight.
If the amount of epoxy ester resin (A) exceeds 90% by weight, the barrier ability of the coating will decrease;
If the amount is less than this, the processability of the coating film decreases, which is not preferable. The carboxyl group-modified polypropylene (C) in the present invention is polypropylene graft-polymerized with an unsaturated carboxylic acid such as maleic acid or maleic anhydride, or an acid anhydride thereof. A carboxyl group-modified polypropylene dispersion can be produced by physically pulverizing carboxyl group-modified polypropylene and dispersing it in a suitable solvent, or by dissolving it in a solvent such as xylene while hot, and then cooling it to disperse the resin in the solution. It can also be obtained by other methods. In the adhesive composition of the present invention, the dispersion of carboxyl group-modified polypropylene (C) is used in an amount of 3 to 100 parts by weight, preferably 3 to 30 parts by weight, based on 100 parts by weight of the solvent-soluble resin. . Resin (C)
If the blending amount is less than 3 parts by weight, the adhesive force to polypropylene film will be small;
If the amount exceeds 1 part by weight, the anticorrosive properties of the solvent-soluble resin will be relatively reduced, which is not preferable. Examples of organic solvents used in the adhesive composition of the present invention include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone, aromatics such as benzene, toluene, xylene, and other alkylbenzenes, methyl cellosolve, and ethyl Cellosolve, cellosolves such as butyl cellosolve, methyl cellosolve acetate, butyl cellosolve acetate, esters such as ethyl acetate, butyl acetate, isopropyl alcohol,
Alcohols such as butyl alcohol and diacetone alcohol, or a mixed solvent thereof can be used. The polypropylene film used in the present invention may be a homopolymer, a copolymer with ethylene or butene, or a polymer blend with polyisobutylene or butadiene rubber. Film thickness is 30~300μ
The range of m is general-purpose and practical. On the other hand, the base metal plates include cold-rolled steel plates, electric or hot-dip galvanized steel plates, steel plates coated with their alloys, electrolytic chromic acid treated steel plates, tin-plated steel plates, stainless steel plates, aluminum plates, copper plates, or foils thereof. etc., and these can be used as they are or those to which a commonly used chemical conversion treatment has been applied. In order to obtain a metal-polypropylene film laminate using the adhesive composition according to the present invention, the adhesive composition is applied onto a metal plate by a conventional method such as roll coating or curtain flow coating so that the thickness after drying is 1. After coating to a thickness of ~50 μm,
Heat and dry for about 0.3 to 20 minutes so that the metal plate temperature becomes 180 to 280℃. Immediately thereafter, the polypropylene film described above is laminated using a roll lamination method. The bonding pressure may be about 0.1 to 20 kg/cm ² . Thereafter, it is cooled to obtain a coated metal plate. (Function) The metal-polypropylene film laminate thus obtained has excellent heat resistance, corrosion resistance, chemical resistance, etc. in addition to good adhesion, so it can be used not only as a general building material but also in fields requiring relatively high corrosion resistance.
For example, it can be sufficiently applied to container materials, etc. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 100 parts by weight of Epicote 1007 (bisphenol A type epoxy resin manufactured by Yuka Ciel Epoxy Co., Ltd.) and 5 parts by weight of sebacic acid were dissolved in 105 parts by weight of cellosolve acetate, and N,N dimethylbenzylamine was dissolved.
Add 0.22 parts by weight and react at 150°C for 4 hours.
An epoxy ester resin composition with a solid content of 50% was synthesized. The acid value of the epoxy ester resin composition produced at this time was 2.1 mg KHO/g of resin. Next, 0.3 mol of bisphenol A and 0.7 mol of p-tert-butylphenol were added to formaldehyde (37%
Aqueous solution) was dissolved in 2.4 mol, 0.2 mol of ammonia (25% aqueous ammonia) was added, and the mixture was reacted at 95°C for 3 hours.
The resulting condensate was extracted with a mixed solvent consisting of 30 parts by weight of methyl isobutyl ketone, 30 parts by weight of cyclohexanone, and 40 parts by weight of xylene, washed with water, left to stand day and night, and the aqueous layer was separated to obtain a resol with a solid content of 60%. A solution of type phenolic resin was synthesized. Then, 77 parts by weight of the epoxy ester resin composition as a solid content was mixed with 23 parts by weight of a resol type phenol resin as a solid content to prepare an epoxy phenol resin solution with a solid content of 52%. To 100 parts by weight of the solvent-soluble resin as a solid content, 12 parts by weight of a solvent dispersion of carboxyl group-modified polypropylene (manufactured by Toyo Ink Mfg. Co., Ltd., trade name: Lioflex 4188, solid content 10%) was added. An adhesive with a concentration of 35.9% by weight was prepared. The adhesive obtained in this way was applied on one side of a 0.32 m/m thick piece of stain-free steel (manufactured by Nippon Steel Corporation, trade name: Can Super) in a dry coating amount of 5/2.
It was coated using a reverse roll coater so that it was ² m2. Next, the steel plate was dried and heated in a gas oven for 30 seconds to reach a temperature of 240°C.
While maintaining the same temperature, immediately use a roll laminator to make a 60 μm thick polypropylene film (manufactured by Idemitsu Petrochemical Co., Ltd., trade name: F-
200S) was laminated at a pressure of 4 kg/cm ² and immediately cooled to produce a metal-polypropylene laminate. Example 2 100 parts by weight of Epicote 1009 (manufactured by Yuka Ciel Epoxy Co., Ltd., bisphenol A type epoxy resin) and 4 parts by weight of azelaic acid were dissolved in 104 parts by weight of cellosolve acetate, and 0.25 parts by weight of N,N-dimethylbenzinamine was dissolved. Parts by weight were added and reacted at 150°C for 5 hours to synthesize an epoxy ester resin composition with a solid content of 50%. The acid value of the epoxy ester resin composition produced at this time was 1.8 mgKOH/g resin. On the other hand, the synthesis and blending of resol type phenolic resin and the solvent dispersion of carboxyl group-modified polypropylene were carried out in the same manner as in Example 1.
A 35.9% by weight adhesive was prepared. A metal-polypropylene film laminate was produced using this adhesive composition in the same manner as in Example 1. Example 3 A metal-polypropylene film laminate was produced in the same manner as in Example 1 except that the amount of carboxyl group-modified polypropylene used in Example 1 was changed to 4 parts by weight, and an adhesive was prepared in the same manner as in Example 1. Example 4 A metal-polypropylene film laminate was produced in the same manner as in Example 1 except that the amount of carboxyl group-modified polypropylene used in Example 2 was changed to 95 parts by weight, and an adhesive was prepared in the same manner as in Example 2. Comparative Example 1 In the synthesis of the epoxy ester resin composition in Example 1, N,N-dimethylbenzylamine was changed to 0.11 parts by weight and the reaction was carried out for 3 hours. The acid value of the epoxy ester resin composition obtained was 13.5. mg
KOH/g resin. Using the epoxy ester resin composition, an adhesive was prepared in the same manner as in Example 1, and a metal-polypropylene film laminate was produced. Comparative Example 2 In place of the azelaic acid used in Example 2, 5 parts by weight of stearic acid was used to synthesize an epoxy ester resin composition. The acid value of the epoxy ester resin composition produced at this time was 3.5 mg.
KOH/g resin. Using the epoxy ester resin composition, an adhesive was prepared in the same manner as in Example 1, and a metal-polypropylene film laminate was produced in the same manner as in Example 1. Comparative Example 3 In Example 1, instead of the epoxy ester resin composition solution, a resin solution in which Epicote 1007 was dissolved in cellosolve acetate to a solid content of 50% was used, and the other conditions were the same as in Example 1. A metal-polypropylene film laminate was produced in the same manner as in Example 1. Comparative Example 4 When a metal-polypropylene film laminate was produced in Example 1 without using the carboxyl group-modified polypropylene, the polypropylene film was easily peeled off by hand, and a good metal-polypropylene laminate could not be obtained. Comparative Example 5 A metal-polypropylene film laminate was produced in the same manner as in Example 1, using only the dispersed carboxyl group-modified polypropylene used in Example 1 as an adhesive. The processing adhesion of the metal-polypropylene film laminates produced in Examples 1 to 4 and Comparative Examples 1 to 5 was measured by an Erichsen test according to JIS K-6744. Then, in order to examine the corrosion resistance including the processed parts, a Dupont impact test (diameter 2/1 inch, load 500g, height 30cm) was performed from the back side at a temperature of 20℃, and then immersed in a 5% acetic acid aqueous solution at a temperature of 37℃. At
After 480 hours had elapsed, the state of rust on the flat and convex parts was visually observed and evaluated. These results are summarized in Table 1. This also shows that the product of the present invention has sufficient adhesion processability and corrosion resistance. It is also found that among epoxy ester resin compositions, the lower the acid value, the better the corrosion resistance.

[Table] (Effects of the Invention) The adhesive layer of the present invention is made by modifying the epoxy resin component with a fatty acid, thereby increasing the molecular weight of the epoxy resin and imparting flexibility. Even if it is formed and processed like a general metal plate, cracks in the adhesive layer at the processed portion are prevented from occurring. The modified product also has high barrier properties against corrosive substances, and can be covered with an adhesive layer against corrosive substances that permeate the polypropylene film. Therefore, it is fully applicable to can processing applications, which have been delayed due to large restrictions on contents.

Claims (1)

[Claims] 1 In a laminate formed by laminating polypropylene films via an adhesive layer formed on a metal base material, the adhesive layer comprises 100 parts by weight of a bisphenol A type epoxy resin and 1 to 20 parts by weight of a saturated dibasic acid. For 100 parts by weight of a solvent-soluble resin consisting of 90-40% by weight of a modified epoxy ester resin composition (A) with an acid value of 10 or less and 10-60% by weight of a resol type phenol resin (B). A metal-polypropylene film laminate, which is a coating film hardened by baking, containing 3 to 100 parts by weight of dispersed carboxyl group-modified polypropylene (C).