JPH0450334B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) This invention relates to the production of a laminate of aluminum foil or aluminum sheet (hereinafter abbreviated as aluminum foil/sheet) and resin film, which is suitably used as a material mainly for producing packaging containers, etc. It is about the method. (Prior art) Conventionally, as a method for producing a laminate of aluminum foil/sheet and synthetic resin film for use in packaging containers, etc., the aluminum foil/sheet is rolled and then used as is, or annealed to achieve the desired hardness. A synthetic resin film was bonded to a material that had been tempered or degreased to remove rolling oil and the like adhering to the surface. Methods for bonding this synthetic resin film include extrusion lamination, heat-sealing pre-formed films, and curing adhesives such as urethane adhesives or thermoplastic adhesives such as ethylene-acrylic acid copolymer. The dry lamination method used is used. (Problems to be Solved by the Invention) These laminates can be used without any practical problems in applications that do not require particularly strong adhesive strength.
There have been problems such as peeling occurring during strong processing such as drawing, and adhesive strength gradually decreasing over time in particularly processed parts of the container after molding, resulting in peeling. The purpose of the present invention is to solve such conventional problems and to obtain a laminate of aluminum foil/sheet and synthetic resin film for use in cases where particularly strong adhesive strength is required for a long period of time. The present invention provides a method for surface treatment of foil/sheet and a method for adhering aluminum foil/sheet to synthetic resin film. (Means for Solving the Problems) The manufacturing method of the present invention has been made to solve the above-mentioned problems, and first, aluminum foil/sheet after rolling or annealing is made with phosphate as the main component. The aluminum foil/sheet is washed in an alkaline bath to remove dirt such as rolling oil on the surface of the aluminum foil/sheet and the fragile layer on the outermost surface of the aluminum oxide film, and then aged for a predetermined period of time to further strengthen the oxide film surface layer. a step of applying an aqueous dispersion adhesive based on an ethylene-based ionomer resin prepared by adding a phosphate or a phosphoric acid ester to the aluminum foil/sheet and then heating and drying the adhesive; The method is characterized in that a synthetic resin film of the same type as this adhesive is adhered by heat fusion to an aluminum foil/sheet on which the adhesive has been applied and dried. The present invention will be explained in more detail below. The aluminum foil/sheet used in the present invention is an aluminum alloy foil or sheet commonly used as a material for manufacturing packaging containers, for example, a JIS H4160 A3003 material foil or sheet. The aluminum foil/sheet is rolled to a predetermined thickness and then tempered to a desired hardness by annealing before use, but the surface layer of the oxide film on the aluminum foil/sheet after rolling or annealing is fragile. When a laminate with a synthetic resin film is manufactured using such aluminum foil/sheet, the peel strength is very weak, and peeling occurs near the interface between the aluminum foil/sheet and the synthetic resin film during molding. . When the film-side surface of this peeled surface is observed using ESCA or the like, a large amount of aluminum oxide is detected, indicating that the surface oxide film of the aluminum foil/sheet has been destroyed. Therefore, in the present invention, the step of degreasing and cleaning with an alkaline bath containing phosphate as a main component removes the surface stains of the aluminum foil/sheet due to residual rolling oil, etc., and also removes the fragile film on the surface layer of the oxide film. It is something. As the alkaline bath, phosphates such as sodium tripolyphosphate are mainly used, and borates, sodium carbonate, sulfates,
By adding nonionic surfactants and anionic surfactants, the pH is approximately 9 to 11 and the surface tension is approximately
The one adjusted to about 33 to 35 dyn/cm is used. Most of the fragile layer on the surface of the aluminum foil/sheet oxide film described above is likely to be removed in the degreasing and cleaning process, and an improvement in adhesion can be seen, but it is still not sufficient and the degreasing and cleaning process is not enough. The aged aluminum foil/sheet is aged in an atmosphere with a temperature of 0 to 80°C and a humidity of 20 to 80% for at least 5 days, preferably 15 to 60 days. It becomes stable and strong. Thereafter, a synthetic resin film is bonded to the aluminum foil/sheet to form a laminate, which can be laminated by extrusion lamination, heat fusion, or bonding using an adhesive. However, in the present invention, adhesive lamination is performed using an aqueous dispersion adhesive based on an ethylene ionomer resin prepared by adding a phosphate or a phosphate ester. Laminated bodies obtained by extrusion lamination or simple heat fusion generally have weak adhesive strength, so dry lamination using a hardening adhesive such as urethane adhesive or a thermoplastic adhesive such as ethylene-acrylic acid copolymer is recommended. When this is done, there is no problem with the initial adhesive strength, but there is a problem that the adhesive strength between the adhesive and the synthetic resin film gradually decreases over time. On the other hand, by using the above water-based dispersion adhesive and using a film made of the same type of resin as the synthetic resin film, it is possible to obtain a laminate with excellent initial adhesive strength and adhesive stability over time. It is. Specifically, an ionomer resin powder such as ethylene or propylene resin is used as the aqueous dispersion adhesive, this powder is added and dispersed in water to form an emulsion, and a phosphate or phosphate ester is added to the emulsion. It is added. Examples of the phosphates include ammonium phosphate, sodium phosphate, potassium phosphate, sodium hypophosphite, sodium pyrophosphate, sodium acid metaconate, and sodium tripolyphosphate. Examples include trimethyl phosphate, triethyl phosphate, tributyl phosphate, monoethyl phosphate, diethyl phosphate, ethyl metaphosphate, ethyl pyrophosphate, etc. The amount of these phosphates or phosphoric esters added is The amount is preferably 0.01 to 3.0% by weight based on 100% by weight of the solid content of the ionomer resin. The adhesive prepared in this way has a very high affinity for the oxide film on the surface of the aluminum foil/sheet,
It exhibits a strong adhesion function to this oxide film. On the other hand, the resin film to be adhered to the aluminum foil/sheet via the aqueous dispersion adhesive is preferably made of the same resin as the resin component constituting the adhesive. That is, a film made of an ionomer resin such as ethylene or propylene is used, and as a result, the film and the aqueous dispersion adhesive have a high affinity for each other, and the two are bonded together using heating and pressure means. When they are bonded, they are firmly heat-sealed to each other, and the adhesive and the film are strongly bonded, and the film and the aluminum foil/sheet are strongly bonded through the adhesive. be. (Functions and Effects) As described above, by degreasing and cleaning the surface of the aluminum foil/sheet using the alkaline bath, most of the fragile layer of the oxide film on the surface of the aluminum foil/sheet is removed. After washing and drying this aluminum foil/sheet, the temperature is 0 to 80℃.
It is thought that the aging treatment for 5 days or more under conditions of humidity of 20 to 80% causes a structural change in the surface of the oxide film, forming a strong and stable oxide film. Following the aging process described above, a water-based dispersion adhesive based on ethylene ionomer resin is applied onto the oxide film of the aluminum foil/sheet, and this adhesive has a high affinity for the oxide film. The adhesive is excellent and forms an extremely strong bond between the adhesive and the oxide film. Next, after drying the adhesive applied to the surface of the aluminum foil/sheet, the resin film is superimposed on the outer surface of the adhesive, and the film and the adhesive are heated and pressurized to heat-fuse them. Let it happen. At this time, since the film and the adhesive are each composed of the same type of resin component, the heat fusion bonding firmly bonds and integrates the film and the adhesive. The aluminum foil/sheet is firmly bonded and integrated with the aluminum foil/sheet. (Examples) Hereinafter, the laminate of the present invention and its manufacturing method will be described with reference to the drawings, along with specific examples. Example 1 First, the thickness is 60 μm made of JIS H4160 A3003 material.
Aluminum foil 1 was used as a sample. In addition, the following was prepared as an alkaline bath for degreasing and cleaning the aluminum foil 1. A 3% aqueous solution of Almeco 36 (manufactured by Henkel Hakusui Co., Ltd.) was used as a degreasing detergent liquid, and 16g/of sodium tripolyphosphate and 3g/of soda carbonate were added to the solution.
An alkaline bath was prepared by containing 1 g of a nonionic surfactant and 1 g of a nonionic surfactant. Next, the aluminum foil 1 is continuously immersed in an alkaline bath adjusted as above and set to a temperature of 65°C to degrease it, and after washing with hot water, the aluminum foil 1 is heated to a temperature of 20°C.
℃, humidity 50% [experiment] and temperature 40℃, humidity 50%
Aging treatment was performed for 1 to 60 days under the following conditions: [Experiment] and 60° C. temperature and 70% humidity [Experiment]. In addition, as a water-based dispersion adhesive that adheres to the aluminum foil 1, sodium phosphate is added to Chemipearl S.300 (manufactured by Mitsui Petrochemical Industries, Ltd.) based on 100% by weight of the ethylene-based ionomer resin component. It was prepared by adding 0.5% by weight. Then, the aqueous dispersion adhesive was applied to the aluminum foil 1 side using a bar coater, and then the adhesive was dried to form an adhesive layer 3 with a thickness of about 5 μm. Next, Himilan 1652 (manufactured by Mitsui Petrochemical Industries, Ltd.) with a thickness of 100 μm was used as the resin film 4 made of ethylene-based ionomer resin, and this resin film 4 was applied to the hydrated oxide film 2 of the aluminum foil 1.
The aluminum foil 1 and the resin film 3 are overlapped on the side, that is, the adhesive layer 3, temporarily bonded by heating and pressing at 80°C, and then heating and pressing for 10 seconds using a drum heated to 170°C to bond the aluminum foil 1 and the resin film 3 together. was glued. At this time, the aluminum foil 1 and the resin film 3
The peel strength in the 180° direction was measured as shown in Table 1. From the data in Table 1, it can be seen that the adhesive strength increases when the aging treatment is performed for 4 to 5 days or more, and that the aging treatment is preferably performed for 30 to 60 days.

[Table] Example 2 As a sample, the same aluminum foil 1 as in the previously described example was used. Moreover, as an alkaline bath for degreasing and cleaning the aluminum foil 1, the following was prepared. As a degreasing detergent, 3 containing Almeco 36 as the main component.
% aqueous solution, sodium tripolyphosphate 18g/
, Sodium borate 5g/, and Sodium carbonate 3g/
An alkaline bath was prepared by containing 3 g of sodium sulfate, 1 g of a nonionic surfactant, and 1 g of an anionic surfactant. Next, the aluminum foil 1 was continuously immersed in the alkaline bath prepared as described above to perform degreasing and cleaning. After this, the aluminum foil 1 is heated at a temperature of 40°C and a humidity of 50°C.
% conditions for 60 days. The aluminum foil 1 and the resin film 3 were bonded together under the same conditions as in Example 1 except for the above. At this time, the aluminum foil 1 and the resin film 3
Regarding the adhesion strength, we measured the peel strength in the 180° direction and found that it was 3.6 at a peeling speed of 200 mm/min.
Kg/15mm width.

[Brief explanation of the drawing]

The drawing is an enlarged sectional view showing an embodiment of the present invention. 1... Aluminum foil, 2... Hydrated oxide film, 3...
Adhesive layer, 4...Resin film.

Claims (1)

[Claims] 1. A process of cleaning aluminum foil or aluminum sheet with an alkaline bath containing phosphate as the main component, and aging the oxide film formed on the surface of the aluminum foil or aluminum sheet for a predetermined period of time by this degreasing and cleaning, After this oxide layer growth step and this aging step, a water-based dispersion adhesive based on an ethylene ionomer resin formulated with phosphates or phosphoric esters is used to remove the adhesive. A method for producing a laminate of aluminum foil or an aluminum sheet and a resin film, which comprises the step of adhesively laminating a resin film made of the same type of resin component on the hydrated oxide film.