JPH0459054B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for producing molded products made of aluminum or aluminum alloy as a base material, and more specifically relates to a method for manufacturing a molded product made of aluminum or an aluminum alloy as a base material, and more specifically, a method for manufacturing a molded product using aluminum or an aluminum alloy as a base material. The present invention relates to a method for manufacturing a cylindrical molded product with one end closed, which is used for applications such as the like, from a plate material made of aluminum or an aluminum alloy by press drawing.

[Prior art] Molded products made of aluminum or aluminum alloy as a base material can be used for cosmetic container top lids, umbrella handles, dials, etc. because the surface treatment gives them the beauty of the metal's inherent luster and a sense of luxury. It is widely used as an exterior material for push buttons, etc.

In conventional molded products of this type, an aluminum oxide film of several tens of microns or more is formed on the surface by anodizing to obtain a decorative effect, surface hardness, and corrosion resistance, but this aluminum oxide film layer is ductile. If this coating layer is formed before molding and then press drawing is performed, cracks will appear on the surface. Therefore, first mold the product into the desired shape and then individually anodize the surface of the molded product. It was being processed. In addition, printing and surface treatment for decoration must be performed after the aluminum oxide film is formed, so these treatments have to be performed on three-dimensional molded products, resulting in very low production efficiency. That is why the cost was so high.

[Problems to be Solved by the Invention] The present invention has been made to solve the problems of the prior art, and can obtain decorative effects, surface hardness, and corrosion resistance comparable to those of conventional products by anodizing. Moreover, it is an object of the present invention to provide a method of manufacturing a molded product by press drawing from a plate material made of aluminum or an aluminum alloy, which can significantly reduce manufacturing costs.

[Means for Solving the Problems] The method of the present invention makes it possible to perform surface treatment on aluminum or aluminum alloy material in its flat state, and then to form it by press drawing. The method is distinctive.

That is, a plate material made of aluminum or an aluminum alloy is first oxidized to form an oxidized layer on its surface. Since this oxidized layer has poor spreadability, its thickness is set to 5 microns or less, preferably 1 micron or less. If the layer thickness is 5 microns or more, cracks are likely to occur during press drawing. The oxidation treatment is preferably carried out using a solution such as dichromic acid or dichromate.

Next, an intermediate layer made of soft plastic is formed on the oxidized layer. As this soft plastic, polyvinyl chloride, ethylene-vinyl acetate copolymer, and other resins can be used.
Polyvinyl chloride is preferred if a decorative pattern is to be printed on this intermediate layer.

Furthermore, a covering layer made of hard plastic is formed on this intermediate layer. Since this coating layer serves as a protective coating, its material is selected from resins having sufficient surface hardness. Typical examples include polyurethane-based and polyacrylic-based resins.

After surface-treating an aluminum or aluminum alloy plate by the above method, press drawing can be performed to obtain a surface-treated molded product as is. In order to increase production efficiency, a wide-area plate is usually surface-treated and punched and press-drawn at the same time, but it is also possible to use plates that correspond to individual molded products. It is effective to use a device called a flow coater to uniformly coat a large area of board material with plastic. Molded products are used as these exterior parts using a molded part made of plastic or the like as a core material.

[Effect] Next, the operation of the present invention will be explained.

According to the method of the present invention, it is possible to form the aluminum or aluminum alloy material without causing any cracks even if it is press-drawn after all the surface treatments have been carried out in its flat state. This is due to the unique laminated structure formed by the method.

That is, the oxidized layer has a corrosion-resistant effect and also has the effect of improving the adhesion of the soft plastic intermediate layer to the substrate made of aluminum or aluminum alloy. Since the thickness of the oxidized layer is limited to 5 microns or less, no cracks will occur even when press drawing is performed. Since the layer thickness is limited, the contribution to corrosion resistance and surface hardness is relatively small, but this is compensated for by the intermediate layer and the hard plastic coating layer.

The intermediate layer made of soft plastic plays the role of a buffer material between the hard coating layer and the oxidized layer, and absorbs deviations between the two during molding.

The hard plastic coating serves as a protective coating and also has a decorative effect.

[Effects of the Invention] As described above, according to the method of the present invention, it is possible to perform surface treatment on the flat plate and then press draw it to form it without causing crumpling. Since a large amount of surface-treated molded products can be obtained at the same time by punching and press-drawing a sheet material, manufacturing costs can be significantly reduced compared to the conventional manufacturing method in which the molded products are individually anodized after molding.

Furthermore, the ability to perform surface treatment on a flat plate is extremely important when applying decorative patterns. That is, a decorative pattern can be easily applied to the surface of a plate material made of aluminum or an aluminum alloy by mechanical processing during spin processing or hairline processing, and then the above-mentioned oxidation treatment is performed, and the intermediate layer and If transparent plastic is used as the surface coating layer, a decorative molded product with a matte and luxurious feel can be obtained. This matte pattern on the machined metal surface also serves to enhance the adhesion of the soft plastic interlayer thereon. Alternatively, a decorative pattern may be applied to the soft plastic intermediate layer by offset printing, and then a transparent covering layer made of hard plastic may be formed. In this case, the soft plastic intermediate layer has the role not only as a cushioning material but also as a printing base.

Examples of the present invention are shown below.

[Example] The surface of an aluminum flat plate with a thickness of 0.5 mm was oxidized with a 0.5 volume % dichromic acid solution, thoroughly washed with water, dried, and then coated with polyvinyl chloride resin using a flow coater. Polyacrylic resin was coated using the same flow coater. After the resin had sufficiently hardened, it was pressed and drawn to obtain a cylindrical molded product with a diameter of 50 mm and a height of 40 mm with one end closed.

Cracks were seen on the surface of the molded product when the layer thickness of the oxidation treatment layer using a dichromic acid solution was 5 microns or more, but when the layer thickness was less than this, no cracks occurred and the surface remained fine after molding. It was possible to obtain an appearance equivalent to that obtained when treated.

Claims (1)

[Claims] 1. After oxidizing the surface of a flat plate material made of aluminum or aluminum alloy to form an oxidized layer of 5 microns or less, forming an intermediate layer made of soft plastic on the oxidized layer, A method for manufacturing a draw-molded product using aluminum or an aluminum alloy as a base material, which further comprises forming a covering layer made of hard plastic on the intermediate layer, and forming this laminated flat plate material by press-drawing. 2. The method for producing a draw-molded product using aluminum or an aluminum alloy as a base material according to claim 1, wherein the oxidation treatment is dichromic acid or dichromate treatment. 3. The method for manufacturing a draw-molded product using aluminum or an aluminum alloy as a base material according to claim 1, wherein the soft plastic is a polyvinyl chloride resin. 4. The method for manufacturing a draw-molded product using aluminum or an aluminum alloy as a base material according to claim 1, wherein the hard plastic is a polyurethane-based or polyacrylic-based resin. 5. Aluminum or aluminum alloy according to claim 1, wherein the oxidation treatment is performed after a decorative pattern is applied to the surface of a flat plate material made of aluminum or aluminum alloy by machining such as spin processing or hairline processing. A method for manufacturing draw-molded products using as a base material. 6. Manufacturing a draw-molded product using aluminum or aluminum alloy as a base material according to claim 1, wherein a decorative pattern is applied to the soft plastic intermediate layer by offset printing, and then a covering layer made of hard plastic is formed. Method. 7. The method for producing a draw-molded product using aluminum or an aluminum alloy as a base material according to any one of claims 1 to 6, wherein the molded product has a cylindrical shape with one end closed.