JPH0311621B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of laminating metal foil and thermoplastics using a water-soluble primer. Conventionally, laminates made of metal foil and thermoplastic plastics have been used as packaging bags to provide barrier properties such as water vapor barrier properties and oxygen barrier properties, and are used to carry substances containing aromatic components, It is used for packaging materials that are easily oxidized. Extruder extrusion coating using a T-die is widely used as a method of laminating metal foil and thermoplastic. The surface needs to be primed. Polyethylene imine, titanate ester, urethane, etc. are widely used as primers, and after applying the primer to the surface of the metal foil using a coating method such as gravure coating or roll coating, the solvent is removed by drying. After that, the molten thermoplastic is extruded and coded using an extruder. However, when the laminate obtained by this method is used as a packaging bag, the interior is filled with a substance that has high permeability to thermoplastics, such as a substance containing an aromatic component, and the bag is sealed and stored. A major problem is that the strength of the laminate between the bag and the bag decreases over time, eventually impairing its function as a packaging bag. Additionally, a method of modifying thermoplastics for the purpose of improving the adhesion between metal foil and thermoplastics is also widely used.
This includes copolymer resins made of ethylene and unsaturated carboxylic acid esters, ionomer resins, and the like. Since the modified thermoplastic resin has adhesive properties with metal foils such as aluminum foil, there is no need to perform primer treatment on the surface of metal foils such as aluminum foil as in the method described above. However, it has not been able to sufficiently meet the need for preserving substances that have high permeability into thermoplastics as described above. Furthermore, we are considering a method in which a chromium polyacrylate complex is used as a primer, the metal foil surface is treated, the solvent is sufficiently dried and removed, and then a copolymer resin consisting of polyethylene and an unsaturated carboxylic acid ester group is extruded and coated. However, the processing temperature during extrusion coating must be set 20 to 80°C higher than normal conditions, and in order to lower the temperature, special methods such as ozone treatment are used to coat the thermoplastic surface. It was necessary to oxidize it sufficiently. Another drawback was that if the surface of the thermoplastic plastic was not sufficiently oxidized, the desired strength of the laminate between the metal foil and the thermoplastic plastic could not be obtained. Further, even if extrusion coating is performed at high temperatures in this manner, there is still the problem that the adhesive strength deteriorates economically when a highly permeable substance is accommodated. The present invention was made in view of these circumstances, and even if highly permeable substances such as aromatic components are stored and stored, they will adhere to metal foil with strong adhesive force, and economically this adhesive strength will decrease. The object of the present invention is to provide a method for manufacturing a laminate without any problems. That is, the present invention provides a layer of a primer composition made by adding and mixing an acid to a primer made of a metal complex of polyacrylic acid on a metal surface, and after sufficiently drying and removing the solvent content of this layer, ethylene and an insoluble layer are provided. This is a lamination method characterized by extrusion coating of a copolymer resin of saturated carboxylic acid or its ester. The metal surface in the present invention is, for example, the surface of aluminum foil, and is a laminate consisting of a laminate of polyester film and aluminum foil, a biaxially stretched extruded polypropylene film/polyethylene film/aluminum foil, or a cellophane/polyethylene film/aluminum foil. It can be applied to any material that has a metal surface exposed on at least one side. In addition, the copolymer resin of ethylene and unsaturated carboxylic acid or its ester refers to ethylene-acrylic acid copolymer resin, ethylene-methacrylic acid copolymer resin, ethylene-acrylate copolymer resin, and ethylene-methyl methacrylate copolymer resin. Alternatively, it refers to an ionomer resin, which is composed of at least one type of resin. Furthermore, the acid to be added and mixed in the primer made of the polyacrylic complex referred to in the present invention is selected from the group of carboxylic acids, such as fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, palmitic acid, and stearic acid, oxalic acid, Carboxylic acids such as malonic acid, adipic acid, maleic acid, fumaric acid, malic acid, benzoic acid, and phthalic acid. Further, the proportion of the acid in the solid content of the primer composition is in the range of 0.3 to 60 weight percent, preferably in the range of 1 to 25 weight percent. Next, the lamination method of the present invention will be explained. The apparatus for obtaining the present invention is a commonly used single-layer or multilayer extrusion molding apparatus, in which a base material consisting of at least two layers including metal foil unwound from an unwinding part, Coating by gravure coating, roll coating, etc. with a solution containing a mixture of acids selected from the above acids in the range of 0.3 to 60 weight percent solids to a primer made of polyacrylic acid metal complex on the side. After applying at least a monomolecular layer using the method and treating the metal foil surface,
Thoroughly dry and remove the solvent in an oven at 100°C to 100°C. Thereafter, a copolymer resin composed of ethylene and unsaturated carboxylic acid or its ester group, which is melted at a temperature of 250°C to 320°C, is extruded and coated on the treated metal foil surface. After the laminate is formed, the desired adhesive strength can be quickly reached by leaving it in an atmosphere of 30° C. to 50° C. and 20% humidity for one day or more. In the present invention, by providing a layer in which an acid is added to the primer made of the above-mentioned polyacrylic acid metal complex between the copolymer resin layer and the metal, the organic part and the metal part of the intermediate layer are respectively copolymerized. This is thought to be because the acrylic acid chains in the resin part strongly adhere to the metal surface. Note that the metal portion in the primer mentioned above is a transition metal such as chromium, cobalt, lead, or nickel. Examples of the present invention will be shown below, and the effectiveness of the present invention will be described. Example 1 Polyester film 12μ (Lumirror P11; Toray Co., Ltd.
Co., Ltd.) and aluminum foil (produced by Tokai Kinzoku Co., Ltd.) as the base material 3. Using the extrusion molding device 4 shown in Fig. 1, the aluminum foil side of the base material was molded as shown below. processed. That is, a primer consisting of a chromium polyacrylate complex (AD1553-155
-1; manufactured by Toyo Morton Co., Ltd.) was diluted with a solvent mixed with water/ethyl alcohol = 1/1 part by weight so that the solid content was 3%, and the acetic acid in the solid content was 6% by weight. Acetic acid was added to the mixture to give a mixed solution 1, and the mixture was stirred lightly. The solution 1 was applied by roll coating, and then dried at an oven temperature of 80°C to remove the solvent. on aluminum foil treated as above.
A laminate 5 is obtained by extruding and coating an ethylene-methacrylic acid copolymer resin (manufactured by Mitsui Polychemical Co., Ltd.) 2 melted at 290°C to a thickness of 30μ.
I got it. The laminate 5 manufactured in this way,
When the lamination strength of the aluminum foil and the ethylene-methacrylic acid copolymer resin layer was measured after being left in a 20% atmosphere at 40°C for 3 days, it was 520g/
It was 15mm. Furthermore, using the laminate 5 obtained according to the present invention, a packaging bag of 10 x 10 cm/cm was made and the contents were a bath air freshener (Bathclin; Tsumura Juntendo Co., Ltd.).
After filling 5.0 g of the product (manufactured by Manufacturer, Inc.), it was sealed by heat sealing and stored in a room at 40°C. The lamination strength of the aluminum foil and the ethylene-methacrylic acid copolymer resin layer was measured after 1 month, 2 months, and 3 months of storage, and the results are shown in Table 1.
It was shown to. Example 2 Ethylene-acrylic acid copolymer resin (EAA; 459; manufactured by Dow Chemical) was used instead of the ethylene-methacrylic acid copolymer resin used in Example 1, and acetic acid was used as the acid added to the polyacrylic acid chromium complex. A laminate was produced in the same manner as in Example 1, using a solution to which 3% by weight of malonic acid was added instead. When the same test as in Example 1 was conducted, a package having excellent performance as shown in Table 1 was obtained. Comparative Example 1 On the aluminum foil of the polyester/aluminum foil laminate used in Example 1, 30μ of ethylene-methacrylic acid copolymer resin (manufactured by Mitsui Polychemical Co., Ltd.) melted at 290°C without primer treatment was applied. The laminate was obtained by extrusion coating in thickness. 40 laminates produced in this way
The lamination strength of the aluminum foil and ethylene-methacrylic acid copolymer resin layer was measured after being left in a 20% atmosphere for 3 days at 450 g/15 mm. Furthermore, a storage test was conducted in the same manner as in Example 1, and the results are shown in Table 1, showing that the laminate strength, which is one of the necessary performances as a packaging bag, was significantly reduced. Comparative Example 2 A primer made of a chromium polyacrylate complex (AD1553-
155-1; manufactured by Toyo Morton Co., Ltd.) diluted with a solvent mixed with water/ethyl alcohol = 1/1 part by weight so that the solid content is 3%. After coating by roll coating, the oven temperature was 80°C. It was dried at ℃ to remove the solvent. on aluminum foil treated as above.
A laminate was obtained by extrusion coating an ethylene-methacrylic acid copolymer resin (manufactured by Mitsui Polychemical Co., Ltd.) melted at 310° C. to a thickness of 30 μm. The laminate produced in this way was heated to 40℃ and 20%
The lamination strength of the aluminum foil and the ethylene-methacrylic acid copolymer resin layer after being left in the atmosphere for 3 days was measured and found to be 350 g/15 mm. Further, the same method and storage test as in Example 1 were performed, and the results are shown in Table 1, showing that the laminate strength, which is one of the performances required for a package, was significantly reduced. 【table】

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an extrusion device used in the present invention, and FIG. 2 is a sectional view of a laminate obtained by the present invention. 1... Mixed solution of polyacrylic acid chromium complex primer and acid, 2... Copolymer resin of ethylene and unsaturated carboxylic acid or its ester, 3... Laminate of polyester and aluminum foil, 4... Extrusion molding Apparatus, 5... Laminate, 51... Polyester, 52... Aluminum foil, 53... Primer composition layer, 54... Copolymer resin of ethylene and unsaturated carboxylic acid or its ester.

Claims (1)

[Claims] 1. A layer of a primer composition made by adding and mixing an acid to a primer made of a metal complex of polyacrylic acid is provided on a metal surface, and after sufficiently drying and removing the solvent content of this layer, ethylene and A lamination method characterized by extrusion coating of a copolymer resin of unsaturated carboxylic acid or its ester. 2. The copolymer resin of ethylene and unsaturated carboxylic acid or its ester is an ethylene-acrylic acid copolymer resin, ethylene-methacrylic acid copolymer resin, ethylene-methyl acrylate resin, ethylene-methyl methacrylate resin, or ionomer resin. A laminating method according to claim 1, characterized in that: 3. The lamination method according to claim 1 or 2, characterized in that at least one type of acid selected from chain carboxylic acids and aromatic carboxylic acids is used as the acid. 4. The lamination method according to any one of claims 1 to 3, wherein the solid content of the primer composition is comprised of 0.3 to 60 weight percent of acid.