JPH0569896B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD This invention relates to a fluororesin-coated aluminum alloy plate for molding. In this specification, "%" indicates "% by weight". Conventional Technology Fluorocarbon resins have excellent chemical resistance, water resistance, oil resistance, heat resistance, etc., and are used as coatings on various products that require these properties.
Such products are made by molding a fluororesin-coated board coated with fluororesin. Conventionally, the above-mentioned fluororesin coated plates for molding processing have been made of pure aluminum substrates such as JISA1100 and JISA1050, and Al-Mg-Mn such as JISA3004.
At least one of both surfaces of the base alloy substrate has been subjected to a base treatment, and the surface that has been subjected to the base treatment is coated with a fluororesin coating film. Problems to be Solved by the Invention However, the fluorine resin-coated plate for molding process provided with a pure aluminum substrate had the following problems. In other words, when applying surface treatment to a substrate using chemical or electrochemical etching methods, etc. before painting, the range of appropriate conditions for obtaining the desired uniform roughness is narrow, and the relationship between the fluororesin coating and the substrate is narrow. There will be variations in adhesion. Furthermore, due to slight variations in the manufacturing conditions of the substrate, the moldability after coating with fluorine resin deteriorates, making it impossible to obtain a product with a low selvage rate, especially during deep drawing. In addition, the following problems occurred with the fluororesin-coated plate for molding, which was provided with an Al-Mg-Mn alloy substrate. In other words, when applying a surface treatment to a substrate using chemical or electrochemical etching methods before painting, the etching speed becomes too fast and a uniformly rough surface cannot be obtained, resulting in poor bonding between the fluororesin coating and the substrate. Adhesion deteriorates. In addition, slight differences in the casting conditions of the slabs used to make the substrates cause non-uniformity in the alloy composition, and etching patterns such as stripes and streaks are formed on the surface of the substrate after etching, which impairs the appearance of the product. Furthermore, since the content of Mg and Mn is high, the amount of work hardening during molding is large, making it unsuitable for re-drawing and spinning. An object of the present invention is to provide a fluororesin-coated aluminum alloy plate for molding that solves the above problems. Means for Solving the Problems The fluororesin-coated aluminum alloy plate for molding according to the present invention contains 0.05 to 0.20% manganese, 0.05 to 0.20% magnesium, and a total of 1.00% or less of iron and silicon as impurities. copper
The surface of an aluminum alloy plate containing 0.20% or less and the balance being aluminum has a distance between peaks and valleys of 5 to 50%.
It has a rough surface with a diameter of 50μ and minute irregularities, and this coarse cotton is coated with a fluorine resin coating. In the above, the aluminum alloy plate to be coated with fluororesin contains 0.05 to 0.20% manganese, 0.05 to 0.20% magnesium, a total of 1.00% or less of iron and silicon as impurities, and copper as impurities.
The reason for using an aluminum alloy plate containing 0.20% or less and the balance being aluminum is as follows. In other words, chemical or electrochemical etching is preferable as a surface treatment method applied to the aluminum alloy plate, which is the substrate to be coated with fluororesin in a fluororesin-coated aluminum alloy sheet for normal molding. In order to improve the adhesion between the coated aluminum alloy plate and the fluororesin, when the aluminum alloy plate to be coated with the fluororesin is etched, conditions (a)... The distance 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. Further, if the rough surface shape due to etching does not have slight irregularities, the above-mentioned adhesion will deteriorate. 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 that, the adhesion between the fluororesin and the aluminum alloy plate will deteriorate, and convex parts exceeding the average height will be exposed from the resin coating, and the resin coating will become thin locally. Pinholes occur after the resin coating is formed, which impairs the smoothness of the resin coating surface, and the aluminum alloy plate comes into direct contact with water, steam, oil, and chemicals, resulting in poor corrosion resistance. Because it will be. Manganese is used as an aluminum alloy for aluminum alloy plates to be coated with fluororesin.
0.05-0.20%, magnesium 0.05-0.20%, iron and silicon as impurities total 1.00% or less,
When using a material containing 0.20% or less of copper as an impurity and the remainder being aluminum, the above three conditions (a) are met.
(b) and (c), and after coating this aluminum alloy plate with fluororesin, when forming and processing this fluororesin-coated aluminum alloy plate, the aluminum alloy plate and fluororesin will become the substrate. It is possible to obtain a fluororesin-coated aluminum alloy plate that can minimize the decrease in adhesion with a coating film, especially in adhesion after molding. This is because if the strength of the aluminum alloy plate is low, if it is molded after being coated with a fluororesin, the amount of deformation will increase and there is a risk that the adhesion with the fluororesin coating will decrease. In the above, manganese and magnesium are 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 is etched under the above conditions ( a)(b)(c)
It has the property of making it possible to satisfy all of the following.
It also has the effect of facilitating the setting of appropriate etching conditions when chemically etching or electrochemically etching an aluminum alloy plate to be coated with a fluororesin. Furthermore, it has the property of reducing the selvage rate when the aluminum alloy plate is subjected to a drawing process after being coated with a fluororesin. However, if the content is less than 0.05%, the above effects cannot be obtained, and if it exceeds 0.20%, the etching rate increases and the above alloy plate meets conditions (a) and (b).
(c) will no longer be satisfied. Furthermore, etching patterns such as stripes and streaks appear on the surface of the plate after etching. Furthermore, the amount of work hardening increases, resulting in poor moldability after coating with fluororesin, such as redrawability and spinning processability. Therefore, the content of manganese and magnesium is 0.05-0.20%
should be selected within the range. Iron, silicon, and copper are contained in aluminum as impurities and have a negative effect on the properties of this type of alloy. Contains more than 1.00% total of iron and silicon and 0.20% copper
If the content exceeds the above, the aluminum alloy plate to be coated with fluororesin will not meet conditions (a), (b), and (c), and the edge height will be high when performing deep drawing on the above alloy plate after coating with fluororesin. Become. In particular, if the copper content exceeds 0.20%, the corrosion resistance of the aluminum alloy plate will deteriorate. Copper content is especially 0.05%
It is preferable that it is less than There are various conventional chemical etching methods and electrochemical etching methods that can be applied to aluminum alloy plates to be coated with fluororesin, and examples of chemical etching methods 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 coating of fluororesin may be performed immediately after etching treatment, or after surface treatment such as chemical conversion treatment or anodization treatment is applied to the roughened area after etching treatment. good. Examples Examples of the present invention will be described below along with comparative examples.

[Table] The six types of aluminum alloys shown in Table 1 were formed into plates with a thickness of 1.5 mm using a conventional manufacturing method, and then annealed. Next, this plate was subjected to electrochemical etching in a conventional manner. That is, electrochemical etching was carried out by performing anodic treatment in a 5% aqueous ammonium chloride solution at a temperature of 27° C. and passing a direct current at a current density of 20 A/dm ² . After that, the tensile strength of the fluororesin-coated aluminum alloy plate obtained by coating the fluororesin to a thickness of 35μ, and the peeling strength before and after molding (the adhesion of the fluororesin coating to the alloy plate) were evaluated. ) and deep-drawn selvage ratio were measured. In addition, the appearance and spinning processability of the product after painting were investigated. The results obtained are shown in Table 2.

[Table] In the column for appearance after painting in Table 2 above, ○ marks indicate that no etching patterns such as stripes or streaks have occurred, and △ marks indicate that etching patterns such as stripes or streaks have slightly occurred. The mark "X" indicates that etching patterns such as stripes and streaks were formed so clearly that the product could not be used as a product. In addition, in the column of spinning workability, ○
The mark indicates that processing is extremely easy, the △ mark indicates that processing is easy, and the x mark indicates that processing is difficult due to increased processing force. Effects of the Invention Since the fluororesin-coated aluminum alloy plate for molding according to the present invention is constructed as described above, the adhesion between the aluminum alloy plate and the fluororesin coating film, especially after the molding process, is strong. Become. Furthermore, it is easy to set appropriate etching conditions for the aluminum alloy plate to be coated with fluororesin. Moreover, when etching is applied to an aluminum alloy plate to be coated with fluororesin, etching patterns such as stripes and streaks do not occur. Also,
This fluororesin-coated aluminum alloy plate for molding has excellent moldability. Furthermore, when this fluorine resin-coated aluminum alloy plate is subjected to deep drawing, the selvage rate becomes smaller.

Claims (1)

[Claims] 1 Manganese 0.05~0.20%, Magnesium 0.05~
0.20% in total, iron and silicon as impurities
The surface of an aluminum alloy plate consisting of 1.00% or less copper, 0.20% or less as an impurity, and the balance aluminum is made into a rough surface with a distance between peaks and valleys of 5 to 50μ and fine irregularities. Fluorine resin-coated aluminum alloy plate for molding processing, which is coated with a fluorine-containing resin coating.