JP2002234112A - Aluminum or aluminum alloy sheet for molding processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminium or aluminum alloy sheet for molding processing capable of being enhanced in moldability and lubricity while suppressing a rise in manufacturing cost. SOLUTION: A polyolefinic ionomer film with a thickness of 0.1-10 μm is formed on the surface of a base material made of aluminum or an aluminium alloy. The polyolefinic ionomer can be formed into a film under such a condition that a film forming temperature is set to a low temperature of about 100 deg.C and a baking time is set to a short time of several sec. Therefore, manufacturing cost can be reduced. The polyolefinic ionomer shows strong adhesion with respect to the surface of the aluminium base material even if substrate treatment is not applied to the base material. Accordingly, if the surface degreasing of the aluminum base material is not performed, coating can be applied to the base material as it is and, from this viewpoint, manufacturing cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forming aluminum or aluminum alloy plate used for an automobile body or the like, and more particularly to a forming aluminum or aluminum alloy plate having improved formability and lubricity.

[0002]

2. Description of the Related Art Aluminum and aluminum alloy materials (hereinafter, aluminum and aluminum alloy are collectively referred to as aluminum) are used in a wide range of fields because of their excellent properties. In particular, due to the recent increase in environmental problems, it has been required to reduce the weight of automobiles, and the use ratio of aluminum materials has been increasing in place of conventional iron-based materials. However, aluminum materials are more expensive than iron-based materials and have drawbacks of low formability, which hinders their widespread use.

For example, the moldability of a material used for automobile parts is extremely important. However, when an aluminum material is used, the moldability is inferior to that of an iron-based material. It is necessary to apply a large amount of lubricating oil having high lubricity. As a result, labor and cost are required as compared with the connection material. Further, the application of a large amount of lubricating oil has a disadvantage that the working environment in a factory is deteriorated.

Means for improving the formability of an aluminum material include adding a large amount of additional elements such as Mg, performing an appropriate heat treatment, and forming a highly lubricious film on the surface of the base material by painting or the like. And so on.

[0005]

However, in the case where a large amount of the additional element is contained, it becomes expensive by the amount of the additional element.
There is a problem that a rapid cooling process is required and the production cost is relatively high.

On the other hand, in a method of forming a film on the surface of a base material by painting or the like, usually, the surface of the base material is degreased and cleaned on a dedicated line, followed by a base treatment, and application and baking of a lubricious coating film. Therefore, there is a problem that the manufacturing cost increases. Further, in the future, an aluminum material having a high bake hard property (bake hardenability) whose strength is improved by heat treatment at a temperature of 150 ° C. or more after molding, for example, JIS
It is expected that the use of 6000 series aluminum alloy materials will be promoted. However, in general, coating paint cannot be formed at a low temperature of about 100 ° C. and is baked at a temperature of about 150 to 300 ° C. There are many. For this reason, if normal coating is performed on the JIS 6000 series aluminum alloy material before forming, baking hard occurs at that point and the strength becomes high, so that the formability deteriorates.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an aluminum sheet for forming which can improve formability and lubricity while suppressing an increase in manufacturing cost. I do.

[0008]

An aluminum or aluminum alloy plate for forming according to the present invention has an aluminum or aluminum alloy substrate and a film formed on the surface of the aluminum or aluminum alloy substrate and having a thickness of 0.1 to 0.1 mm. A polyolefin-based ionomer film having a thickness of 10 µm.

In the present invention, since a polyolefin-based ionomer film having higher lubricity than the substrate is formed on the surface of the substrate, lubricity is improved. In addition, since the polyolefin-based ionomer film can be baked at a temperature of about 100 ° C., even if a material having a high bake hard property such as JIS 6000-based aluminum alloy is used as a base material, the film is hardened by forming the film and moldability is improved. Reduction is suppressed.

The lubricity can be further improved by adding 1 to 60% by mass of a lubricant to the polyolefin ionomer film. As the lubricant, for example, polyolefin can be used. When the aluminum or aluminum alloy substrate is made of a JIS 6000-based aluminum alloy, the strength can be increased by performing a heat treatment at, for example, 150 ° C. or more after the forming process.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The aluminum plate for forming according to the present invention will be further described below. In the aluminum sheet for forming according to the present invention, the thickness of the aluminum or aluminum alloy substrate is 0.1 to 1 on the surface thereof.
A polyolefin ionomer film of 0 μm is formed.

The polyolefin ionomer has a film forming temperature of about 100 ° C. due to its molecular structure.
With respect to the baking time, a film can be formed in a short time of several seconds. For this reason, manufacturing costs can be reduced.

[0013] The polyolefin-based ionomer is
It has strong adhesion to the surface of the aluminum substrate even if no underlying treatment is performed. For this reason, if the surface of the aluminum substrate is degreased, the coating can be performed as it is, and in this regard, the manufacturing cost can be reduced.

Therefore, even when a new equipment is introduced, the cost is lower than when a conventional coating equipment is introduced.

[0015] The polyolefin-based ionomer film becomes less expensive as it becomes thinner. However, if the thickness is less than 0.1 µm, there is a possibility that an unpainted portion may be generated, and it may be difficult to manufacture the film. On the other hand, when the thickness of the polyolefin-based ionomer film exceeds 10 μm, the effect of improving moldability is saturated and the cost increases. Therefore,
The thickness of the polyolefin ionomer film is 0.1 to 10 μm.

Although the composition of the substrate is not particularly limited, the polyolefin-based ionomer film can be formed at a temperature of about 100 ° C. as described above.
Even when a JIS 6000 series alloy material is used, bake hardening is prevented from occurring before molding. Therefore, in consideration of improvement in strength after molding, JIS having high bake hard properties
It is desirable to use a 6000 series alloy material. In addition,
Regarding the surface condition of the aluminum base material, it is sufficient that the oil content on the surface is sufficiently removed and the applied paint is not repelled, but before applying the paint, degreasing, pickling, etching It is desirable that a process or a combination of these processes is performed.

Further, it is desirable that the polyolefin-based ionomer film contains a lubricant. The lubricant is required to improve the lubricity and not to hinder the adhesion between the lubricant and the aluminum base material. As such a lubricant, for example, polyolefin is desirable. However, if the proportion of the lubricant in the entire polyolefin-based ionomer film is less than 1% by mass, a large effect of improving the moldability is not recognized. On the other hand, when the proportion of the lubricant exceeds 60% by mass, the effect of improving the moldability is saturated and the formation of the polyolefin ionomer film may be hindered. Therefore, the proportion of the lubricant in the entire polyolefin-based ionomer film is desirably 1 to 60% by mass.

In forming the polyolefin ionomer film, it is desirable to use a water-soluble solvent containing almost no organic solvent as a coating applied to the surface of the aluminum substrate. Such a water-soluble solvent is
Less likely to cause environmental pollution from the stage of its manufacturing process,
In addition, the organic solvent is not discharged even when forming the coating film. For this reason, since an exhaust device and an explosion-proof device are not required, the cost for equipment is reduced.

As a method of applying the paint, it is desirable to apply the paint to the surface of the aluminum substrate using a general roll coater, but the paint may be applied by spraying. After forming a coating film by these methods, baking may be performed.

[0020]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples that fall outside the scope of the claims.

First, the surface of an aluminum alloy base material having a thickness of 0.7 mm and shown in Table 1 was subjected to alkali degreasing, and the surface of the base material was pickled with nitric acid. Then, Table 1 below
Was formed on the surface of the substrate.

In Examples 1 to 9 and Comparative Examples 12 to 14, a paint was applied to the surface of the substrate by a roll coating method, heated until the sheet temperature reached 110 ° C., and then baked for cooling. At this time, the water-dispersed polyolefin-based ionomer paint (ethylene-crosslinked with Na-
(Methacrylic acid copolymer) was used as a paint. Also,
In Examples 3 to 9 and Comparative Example 14, a lubricant was added to the paint after the paint was applied. For the polyurethane coatings of Comparative Examples 10 and 15, and the polyester coating of Comparative Example 11, the coating was applied by a roll coating method, then heated until the sheet temperature reached 200 ° C., and then subjected to a baking treatment of cooling. Formed.

The film thickness of the film was measured by a film thickness meter, and the mass of the aluminum alloy plate on which the film was formed was measured before and after the film was peeled off, and was converted into a density.

[0024]

[Table 1]

Next, as an evaluation of lubricity, a friction coefficient was measured using a Bowden friction tester.

As an evaluation of the moldability, a rectangular cylinder was drawn by an Erichsen tester, and a forming limit height (square cylinder drawn height) was obtained. The square tube diaphragm has a wrinkle holding force of 19.6 kN.
The punching speed was set at 10 mm / min. In addition, the cross-sectional shape of the punch has a side length of 40 mm.
Are chamfered with a radius of 5 mm at the four corners.

[0027]

[Table 2]

As shown in Table 2 above, in Examples 1 to 9, since an appropriate film was formed on the substrate,
A low coefficient of friction and a high rectangular cylinder drawing height could be obtained.

On the other hand, in Comparative Examples 10, 11 and 15, since a polyurethane film and a polyester film were formed as films, respectively, although excellent moldability was obtained, the baking temperature during film formation was 200 ° C. high. For this reason, the equipment becomes large and the equipment cost increases. Further, in Comparative Example 15, the base material was JIS 6111-
Because of the O material, bake hard occurred during baking of the film, and the moldability was reduced.

In Comparative Example 12, the moldability and lubricity were low because the thickness of the film was less than the lower limit of the range of the present invention.

In Comparative Example 13, although the film thickness exceeded the upper limit of the range of the present invention, high moldability and lubricity were obtained, but the film thickness was lower than that of Examples 1 to 9. The effect of increasing the thickness is not obtained, and is wasted.

In Comparative Example 14, since the content of the lubricant in the film was high, the adhesion to the base material was low, and the film could not be formed. I couldn't do that.

In Comparative Example 16, since no film was formed, the lubricity was extremely low and the moldability was low.

[0034]

As described in detail above, according to the present invention,
Since the polyolefin-based ionomer film having higher lubricity than the base material is formed on the surface of the base material, the lubricity can be improved. As a result, even in the case where the conventional molding is used for a part that cannot be formed without lubricating oil, the molding may be performed without applying lubricating oil. The polyolefin-based ionomer film is 100
It can be baked at about ℃
Even when a material having a high bake hard property such as an S6000-based aluminum alloy is used as a base material, it is possible to suppress a decrease in formability due to hardening due to film formation. Therefore, by using a material having such a high bake hard property as a base material and performing a predetermined heat treatment after the molding, the strength can be improved. Further, it becomes possible to use a low-priced material having relatively low moldability as a base material,
It can be widely used as molded parts for automobiles, parts for household appliances, materials for civil engineering and construction, and the like.

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Claims (4)

[Claims] 1. A molding process comprising: an aluminum or aluminum alloy substrate; and a polyolefin-based ionomer film formed on the surface of the aluminum or aluminum alloy substrate and having a thickness of 0.1 to 10 μm. Aluminum or aluminum alloy plate. 2. The aluminum or aluminum alloy sheet according to claim 1, wherein the polyolefin-based ionomer film contains 1 to 60% by mass of a lubricant. 3. The aluminum or aluminum alloy sheet according to claim 2, wherein the lubricant is a polyolefin. 4. The aluminum or aluminum alloy plate for forming according to claim 1, wherein the aluminum or aluminum alloy substrate is made of a JIS 6000-based aluminum alloy.