JPH0677968B2 - Method for coating tetrafluoroethylene resin film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for coating a tetrafluoroethylene resin film on an aluminum or aluminum alloy plate (hereinafter referred to as aluminum plate together), and more specifically, After forming a hydrated oxide film on an aluminum plate, it is treated with an aminosilane compound, or a thermoplastic fluororesin layer is provided on the surface without treatment, and a method for heat-sealing a tetrafluoroethylene resin film Is.

(Prior Art) The applicant has already filed a patent application for a method of heat-sealing a thermoplastic fluororesin film on an aluminum plate as Japanese Patent Application No. 56-202279 (see JP-A-58-102725). . However, in the process of application development, among the thermoplastic fluororesins, especially the tetrafluoroethylene resin has a very high melt viscosity, so that the adhesive force is high with other thermoplastic resin films such as tetrafluoroethylene-hexafluoropropylene copolymer resin film. It was found to be at a low level compared to the above, and there was a problem that it could not be used when subjected to severe processing.

(Problems to be Solved by the Invention) In view of such circumstances, the present inventors have conducted intensive studies to solve the above problems and improve the invention of Japanese Patent Application No. 56-202279. Above all, it is extremely excellent in heat resistance and wear resistance, and further uses sliding materials, heat resistant sealing materials, and other tetrafluoroethylene resin films that are expected to be used in various fields, and withstand molding processes that could not be obtained in the past. The method for producing a material having adhesiveness has been completed.

(Means for Solving Problems) That is, according to the present invention, after forming a hydrated oxide film on an aluminum or aluminum alloy plate in advance, a thermoplastic fluororesin layer is provided on the surface, and then a tetrafluoroethylene resin film is formed. A method for coating a tetrafluoroethylene resin film, which is characterized by heat fusion, and a hydrated oxide film is previously formed on an aluminum or aluminum alloy plate, which is subsequently treated with an aminosilane compound, and then thermoplastic fluorine is applied to the surface. The present invention provides a method for coating a tetrafluoroethylene resin film, which comprises providing a resin layer and then heat-sealing the tetrafluoroethylene resin film.

Hereinafter, the method of the present invention will be described in more detail.

The aluminum plate used in carrying out the method of the present invention is
Either a commercially available ordinary aluminum plate or an aluminum alloy plate can be applied, but it is suitable to use a plate on which oils and fats do not adhere when used. The aluminum plate first forms a hydrated oxide film, and the following two methods can be adopted as the method.

First, as the first method, there is a method of immersing in an aqueous solution containing a basic organic compound in a substantially boiling state at 90 ° C. or higher for 1 to 15 minutes, preferably 3 to 7 minutes. Specific examples of the basic organic compound here include amines such as triethanolamine, diethanolamine, and monoethanolamine. At least one of these is an ion having a specific resistance of 500 × 10 ⁴ Ωcm or more. 0.2 to 1.5% by volume in exchanged water. Preferably, a weakly alkaline aqueous solution in which 0.3 to 0.7% by volume is dissolved is used.

The second method is to wash the aluminum that has been subjected to the chemical conversion treatment by the above method, and then again in an aqueous solution containing an alkali silicate at a boiling point of 90 ° C. or higher for 1 to 15 minutes, preferably 3 to 7 minutes. It is a method of dipping and re-chemical conversion treatment.
As the alkali silicate, for example, it is preferable to use sodium silicate known as water glass having a SiO ₂ / Na ₂ O molar ratio of 2.0 to 4.0, and a SiO ₂ / Na ₂ O molar ratio of 1
It is also possible to use sodium metasilicate. The concentration of these alkali silicates is 0.35 to 1.05% by volume (0.5 to 1.5 by weight) in ion-exchanged water with a specific resistance of 500 × 10 ⁴ Ωcm or more.
%), Preferably 0.5-0.84% by volume (0.7-1.2% by weight)
%) A dissolved aqueous solution is preferable.

The film obtained by the above two hydrated oxide film conversion methods has a fine migraine structure when observed with an electron microscope, and this structure has a higher tentacle density and a higher density when re-formed. As described in the examples described later, the effect is exerted more greatly on the adhesive force.

The aluminum plate thus subjected to the chemical conversion treatment by the above-mentioned two methods is washed with water, sufficiently dried, and then moved to the next step.

The first method is a method of subsequently forming a thermoplastic fluororesin layer on the surface of the aluminum plate, and the other method is that the surface of the aluminum plate is first treated with an aminosilane compound solution and then the surface of the thermoplastic fluorine resin is treated. This is a method of forming a resin layer.

The aminosilane compound acts to further increase the adhesive force between the thermoplastic fluororesin layer and the aluminum base. Many silane compounds such as amylsilane, vinylsilane, and mercaptosilane exist in addition to the aminosilane compound, but in the method of the present invention, the contribution to the adhesive force is small except for the aminosilane compound. As a method for treating the aminosilane compound solution, any method such as dipping, brush coating, spray coating, or roll coater coating may be appropriately selected. The formed film thickness is as thin as possible, and it is more preferable to control it uniformly.

Next, a thermoplastic fluororesin layer is formed,
As the thermoplastic fluororesin used here, tetrafluoroethylene-hexafluoropropylene copolymer resin, tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin, tetrafluoroethylene-ethylene copolymer resin, etc. can be prepared by heat treatment. A resin having a property of being melted by heat is used. As a method of forming these resin layers, a method of coating and baking with a resin dispersion or powder resin, and more preferably a method of heat fusion in an extremely thin film form is adopted. The formation of the resin layer by the film is more preferable from the viewpoint that a uniform thickness can be obtained over the entire surface and the stability of the adhesive force, and from the viewpoint of obtaining higher adhesive force, the thickness of these resin layers is It is preferable to control in the range of 3 to 25 µ. When the thickness of the coating layer is out of the above range and is thin, sufficient adhesion cannot be obtained. On the contrary, when the coating layer is thick, the resin layer itself is broken, which is not preferable for adhesion.

The method of subsequently coating the tetrafluoroethylene resin film on the thermoplastic fluororesin layer thus obtained is not particularly limited, but it is a thermocompression bonding method using a hot press or a thermocompression bonding method using a heat roller. Should be selected. The conditions for thermocompression bonding may be selected by combining the three factors of temperature, pressure and time so that the tetrafluoroethylene resin film can be sufficiently adhered onto the thermoplastic fluororesin layer, and the individual conditions are not particularly limited. It is not something that will be done. The thickness of the tetrafluoroethylene resin film is not particularly limited as long as it can be coated by thermocompression bonding or the like.

The tetrafluoroethylene resin film layer formed by the method of the present invention has a strong adhesive force between the aluminum base and the thermoplastic fluororesin layer and between the thermoplastic fluororesin layer and the tetrafluoroethylene resin layer. Adhesion is improved compared to heat-sealing the tetrafluoroethylene resin film layer directly to the aluminum base, and it became possible to use it for severe molding processing.

(Examples) Next, the method of the present invention will be described in more detail with reference to Examples of the present invention while comparing with Comparative Examples, but the method of the present invention is not limited to these Examples.

Example 1 An aluminum plate (10150-H24 material) having a plate thickness of 0.6 mm was degreased with a weak alkaline solvent, and then the specific resistance was 500 × 10 ⁴ Ω.
0.5% by volume of triethanolamine in cm ion-exchanged water
After being dissolved and immersed in a weakly alkaline aqueous solution adjusted to pH 10 at 95 ° C. for 5 minutes for chemical conversion treatment, it was washed with water and thoroughly dried.

Next, 12.5μ tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin film was continuously supplied to the surface of the aluminum plate, and thermocompression-bonding treatment was performed with a heat roll.
The 50 μm tetrafluoroethylene resin film was coated by the same method as above.

When the adhesion of the obtained tetrafluoroethylene resin film was measured by a 180 peel test according to JIS K-6854, the obtained plate showed a peel strength of 5.0 kg / inch width.

Furthermore, when deep drawing was carried out in a container shape with a diameter of 200 mm and a height of 120 mm at a drawing ratio of 0.52, molding could be performed without any problems.

Example 2 The same aluminum plate as in Example 1 was subjected to chemical conversion treatment in the same manner as in Example 1, and the aluminum plate was washed with water to give a specific resistance of 500 × 10 ^4.
The pH was adjusted to 10 by adding 0.7% by volume of sodium silicate with a SiO ₂ / Na ₂ O molar ratio of 3.14 to ion exchanged water of Ωcm.
It was dipped in an aqueous solution at 5 ° C. for 5 minutes for re-chemical conversion treatment, washed with water and dried. Then, in the same manner as in Example 1, 12.5 μ of tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin film was continuously supplied to the surface of the aluminum plate and subjected to thermocompression bonding with a heat roll, followed by 50 μ of tetrafluoride. The ethylene resin film was coated with the same method as above.

The obtained plate was measured for adhesion of a tetrafluoroethylene resin film by the same 180 peel test as in Example 1, and showed a peel strength of 5.5 kg / inch width.

Further, when deep drawing was carried out in the same container shape as in Example 1, molding could be carried out without any problems.

Example 3 After a re-chemical conversion treatment was carried out in the same manner as in Example 2, an aminosilane compound solution (A-1100 manufactured by Nippon Unicar Co., Ltd.) was applied and dried on the surface of the aluminum plate that had been washed with water and dried, and then with Examples 1 and 2. Similarly, 12.5μ tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin film, 50μ
Was coated with a hot roll.

When the adhesion of the tetrafluoroethylene resin film was measured on the obtained plate by the same 180 peel test as in Example 1, a peel strength of 6 kg / inch width was shown.

Further, when deep drawing was carried out in the same container shape as in Example 1, molding could be carried out without any problems.

Comparative Example 1 The same aluminum plate as in Example 1 was degreased with a weak alkaline solvent, and then the plate was coated with a 50 μm tetrafluoroethylene resin film by a hot roll as in Example 1.

The adhesion of the tetrafluoroethylene resin film of the obtained plate was measured by the same 180 peel test as in Example 1, and only a peel strength of 0.5 kg / inch width was obtained, which could not be subjected to deep drawing. .

Comparative Example 2 An aluminum plate which had been subjected to a re-chemical conversion treatment in the same manner as in Example 2 was washed with water and dried, and then the plate was coated with a 50 µ tetrafluoroethylene resin film by a hot roll in the same manner as in Example 1. went.

When the adhesive strength of the tetrafluoroethylene resin film was measured in the same 180 peel test as in Example 1 on the obtained plate, only a peel strength of 1.5 kg / inch width was obtained.

Further, when deep drawing was performed in the same manner as in Example 1, local peeling of the tetrafluoroethylene resin film layer occurred,
The desired shape could not be formed.

(Effect of the invention) As described in detail above, the aluminum plate coated with the tetrafluoroethylene resin film obtained by the method of the present invention makes use of heat resistance and abrasion resistance, which are extremely excellent features of the tetrafluoroethylene resin film. In addition, the adhesive strength between the aluminum base and the thermoplastic fluororesin of the intermediate layer and the tetrafluoroethylene resin film layer is strong, and the deep drawing that could not be achieved with the aluminum base and the tetrafluoroethylene resin film alone. It is a sound composite coating that can withstand molding processing such as processing and impact processing, and the method of the present invention is industrially valuable as a method for providing such an effective composite coating.

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Claims (6)

[Claims] 1. A hydrated oxide film is formed on an aluminum or aluminum alloy plate in advance, a thermoplastic fluororesin layer is provided on the surface, and then a tetrafluoroethylene resin film is heat-sealed. Method for coating fluorinated ethylene resin film 2. A thermoplastic fluororesin layer comprising tetrafluoroethylene-hexafluoropropylene copolymer resin, tetrafluoroethylene-
The method according to claim 1, which is one selected from a perfluoroalkoxyethylene copolymer resin or a tetrafluoroethylene-ethylene copolymer resin. 3. The method according to claim 1, wherein the thermoplastic fluororesin layer is a film layer. 4. A hydrated oxide film is formed on an aluminum or aluminum alloy plate in advance, which is subsequently treated with an aminosilane compound, a thermoplastic fluororesin layer is provided on the surface, and a tetrafluoroethylene resin film is then heated. Method for coating tetrafluoroethylene resin film characterized by fusion bonding 5. A thermoplastic fluororesin layer comprising tetrafluoroethylene-hexafluoropropylene copolymer resin, tetrafluoroethylene-
The method according to claim 4, which is one selected from a perfluoroalkoxyethylene copolymer resin or a tetrafluoroethylene-ethylene copolymer resin. 6. The method according to claim 4, wherein the thermoplastic fluororesin layer is a film layer.