JPS6356062B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD This invention relates to a fluororesin-coated aluminum alloy plate in which at least one of both surfaces is coated with a fluororesin. In this specification, [%] indicates [% by weight]. Prior Art and Its Problems Fluororesin has excellent chemical resistance, water resistance, oil resistance, heat resistance, etc., and is used by coating various products that require these properties. Such products are made by molding a fluororesin-coated aluminum alloy plate. Conventionally, the above-mentioned fluororesin-coated aluminum alloy plate has been prepared by applying a surface treatment to at least one of both sides of an aluminum alloy plate made of A3004 alloy or a commercially available Al-Mg-Mn alloy. The surface treated with this base is coated with a fluororesin coating. The above-mentioned surface treatment has been carried out by a sandblasting method, a primer coating method, a chemical or electrochemical etching method, or the like.
However, the sandblasting method has a problem in that the resulting unevenness is rough and the adhesion between the fluororesin coating film and the substrate is poor. According to the primer coating method, there is a problem in that the adhesion between the fluororesin coating film and the substrate deteriorates due to moisture, moisture, and the like. Furthermore, although the etching method can solve the above-mentioned problems of the sandblasting method and the primer coating method, when conventionally used aluminum alloys such as A3004 alloy are used as the substrate, fluorine still remains. The adhesion between the resin coating film and the substrate was not sufficient, and there was a risk that the fluororesin coating film and the alloy plate would peel off in products made from this alloy plate. This invention has been made in view of the above circumstances, and provides a fluororesin-coated aluminum alloy plate that has greater adhesion between an aluminum alloy plate serving as a substrate and a fluororesin coating than conventional ones. The purpose is to Means for Solving the Problems The fluororesin-coated aluminum alloy plate according to the present invention contains 0.5 to 3% iron and silicon as impurities.
0.15% or less each of copper and manganese as impurities
At least one of both sides of the aluminum alloy plate containing 0.1% or less and the balance being aluminum is made into a rough surface having a distance between crests and valleys of 5 to 50 μ and fine irregularities, and this rough surface is It is coated with a base resin coating. In the above, the aluminum alloy plate to be coated with fluororesin is an aluminum alloy plate containing 0.5 to 3% iron, 0.15% or less silicon as impurities, 0.1% each copper and manganese as impurities, and the balance aluminum. The reason is as follows. In other words, chemical or electrochemical etching is preferable as the base treatment applied to the aluminum alloy plate, which is the substrate to which the fluororesin is usually coated, as described above. When etching an aluminum alloy plate to be coated with fluororesin to improve the adhesion between the aluminum alloy plate and the fluororesin, condition (a)...distance between peaks and valleys in the unevenness caused by etching. must be within the range of 5 to 50μ. Condition (b)...The rough surface form due to etching becomes minute irregularities. Condition (c): Etching is almost uniform. It is necessary to satisfy all three conditions. This is because if the distance between the peaks and valleys in the unevenness caused by etching is less than 5μ, the above-mentioned adhesion will be poor, and if it exceeds 50μ, a large amount of fluororesin will be required. In addition, if the rough surface formed by etching does not become fine irregularities, the adhesion will be poor. Furthermore, if the etching is uneven, protrusions that protrude from the average height (referring to the height of the protrusions that are almost uniform among the protrusions with height differences caused by etching) will occur.
If fluororesin is painted on top of it, the adhesion between the fluororesin and the aluminum alloy plate will be poor, and convex parts exceeding the average height will be exposed from the resin coating, and the resin coating will be thin locally. As a result, pinballs occur after the resin coating is formed, which impairs the smoothness of the resin coating surface.In addition, the aluminum alloy plate comes into direct contact with water, steam, oil, fat, and chemicals, resulting in poor corrosion resistance. Because it will get worse. As an aluminum alloy plate to be coated with fluororesin, 0.5 to 3% iron and 0.15 silicon as impurities.
% or less, iron and manganese as impurities each 0.1
The reason why an aluminum alloy plate is used is that the aluminum alloy plate satisfies all three conditions (a) to (c) above and has excellent etching properties. In the above, iron is contained in aluminum, so that when the aluminum alloy plate to be coated with fluororesin is subjected to ordinary chemical etching or electrochemical etching, the alloy plate meets the above conditions (a). It has the property of making it possible to satisfy both (b) and (c). The reason is not clear, but
Iron is potentially more noble than aluminum and has a wide range of solid solubility in aluminum, so when iron is included in aluminum,
It is thought that by chemically or electrochemically etching the alloy plate satisfies the above conditions (a), (b), and (c). However, if the content is less than 0.5%, the above alloy plate meets condition (a).
As conditions (b) and (c) are no longer satisfied, the crystal grains become coarser and an etched pattern appears when etched, resulting in loss of commercial value.If it exceeds 3%, coarse crystallized substances occur and the above alloy plate meets condition (a). (b) and (c) will no longer be satisfied. Therefore, the iron content should be selected within the range of 0.5 to 3%, with around 1% being particularly preferred. Silicon, copper, and manganese are contained as impurities in aluminum and have a negative effect on the properties of this type of alloy.If the silicon content exceeds 0.1%, the above alloy plate will meet condition (a).
(b) and (c) are no longer satisfied, and the edge height becomes high when the above-mentioned alloy plate is formed by deep drawing after being coated with fluororesin. If the copper content exceeds 0.1%, the corrosion resistance of the alloy plate will deteriorate. If the manganese content exceeds 0.1%, the alloy plate will no longer satisfy condition (c) and the surface will become rough. Therefore, the content of these impurities is less than 0.15% silicon.
Copper should be below 0.1% and manganese below 0.1%. There are various conventional chemical etching methods and electrochemical etching methods that can be applied to the aluminum alloy plate, and examples of the chemical etching method include immersion in an aqueous hydrochloric acid solution. Further, as an electrochemical etching method, for example, there is a method of anodic treatment using a direct current in an aqueous solution containing an electrolyte made of chloride. The coating of fluororesin on the roughened aluminum alloy plate by etching is carried out by a conventional method. Furthermore, the fluororesin coating may be applied immediately after etching treatment, or after surface treatment such as chemical conversion treatment or anodic oxidation treatment is applied to the roughened area after etching treatment. . Embodiments Examples of the present invention will be described below with reference to the drawings. In the fluororesin-coated aluminum alloy plate 1 according to the present invention, one side of the aluminum alloy plate 2 is a rough surface having a distance H between peaks and valleys of 5 to 50μ and fine irregularities 3, and this surface is made of fluorine resin. It is coated with a resin coating film 4. The aluminum alloy plate 2 contains 0.5 to 3% iron and silicon as an impurity.
0.15% or less each of copper and manganese as impurities
Consists of an aluminum alloy containing 0.1% or less and the balance being aluminum. Next, the results of an evaluation test conducted on the fluororesin-coated aluminum alloy plate of the present invention and a comparative product will be shown. Alloy A: Iron 0.74%, Silicon 0.09%, Manganese 0.01
% and 0.01% or less of copper, with the balance being aluminum. Alloy B A3004. Alloy C Al-Mg-Mn alloy (commercial product) The above three types of aluminum alloys were made into a plate with a thickness of 1.5 mm by a conventional manufacturing method, and then annealed. Next, after applying chemical etching as usual, i.e. 15%
The tensile strength and peeling strength before and after molding of the fluororesin-coated aluminum alloy plate obtained by immersing it in aqueous hydrochloric acid solution for 7 minutes and then coating it with fluororesin to a thickness of 35 μm (fluororesin coating film (representing the adhesion force to the alloy plate) was measured. The results obtained are shown in the table below.

[Table] As is clear from the above table, the fluororesin-coated aluminum alloy plate according to the present invention has extremely high adhesion between the aluminum alloy plate and the fluororesin coating film compared to the conventional one. Effects of the Invention As described above, the fluororesin-coated aluminum alloy plate according to the present invention is made of aluminum containing 0.5 to 3% iron, 0.15% or less silicon as impurities, 0.1% each copper and manganese as impurities, and the balance being aluminum. At least one of both sides of the alloy plate is a rough surface with a distance between peaks and valleys of 5 to 50μ and minute irregularities, and this rough surface is coated with a fluororesin coating film. Therefore, it is possible to obtain a fluororesin-coated aluminum alloy plate with a high adhesion between the aluminum alloy plate and the fluororesin coating.

[Brief explanation of the drawing]

The drawings are cross-sectional views showing embodiments of the invention. 1... Fluorine resin coated aluminum alloy plate, 2...
Aluminum alloy plate, 3...Irregularities, 4...Fluorine resin coating, N...Distance between peaks and valleys.

Claims (1)

[Claims] 1 0.5-3% iron, 0.15% silicon as an impurity
Below, 0.1% each of copper and manganese as impurities
At least one of both sides of an aluminum alloy plate containing the following and the remainder being aluminum,
A fluororesin-coated aluminum alloy plate having a rough surface with a distance between peaks and valleys of 5 to 50μ and fine irregularities, and this rough surface is coated with a fluororesin coating film.