JPH09299875A - Coated metal sheet with high resistance against scratch and molding characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high molding characteristic and resistance against scratch by mixing at lest, one type each of wax, at a melting point higher and lower than the temperature of a molding die at the time of molding, which are contained in an organic or an inorganic skin formed on a metal sheet. SOLUTION: In a coated metal sheet used for an automobile and electric home appliances, an organic or an inorganic skin mixed with at least, one type each of wax, with a melting point higher and lower than the temperature of a molding die at the time of molding, which is contained in the organic or the inorganic skin formed on the metal sheet, is applied on both faces or one of the faces of the metal sheet, in such a way that the thickness of the skin is at least, 0.1μm and 300μm or less. Thus it is possible to make the coagulation between the molding die and the skin hardly occur and effectively prevent the skin from becoming scratched by mixing at least, one type each of wax, at a melting point higher and lower than the temperature of the molding die at the time of molding, which are contained in the organic or the inorganic skin and melting the wax at a melting point lower than the temperature of the molding die to cover the skin surface with the molten wax.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated metal plate used for automobiles and home electric appliances, which is excellent in scratch resistance and formability.

[0002]

2. Description of the Related Art Conventionally, home electric appliance manufacturers and automobile parts manufacturers use cold-rolled steel sheets or surface-treated steel sheets to form parts,
It was painted in a later process. However, with the aim of reducing the cost by reducing the process by omitting the process, the solvent used for painting has a negative impact on the human body and the natural environment, and the omission of painting by users has been advanced. As a result, the coated steel sheet pre-painted by the material manufacturer is processed by the user by press forming or the like, which causes serious problems such as scratches on the coating film and formability. Regarding the scratches during processing, special measures are taken such as applying special plating to the mold and frequently performing mold maintenance, but these are the shapes that increase the manufacturing cost.

It is known that the hardness of the coating film is increased as a measure for improving the scratch resistance from the characteristics of the coating film. However, increasing the hardness of the coating film lowers the deformability of the coating film. The moldability of (3) is deteriorated and defects such as coating film breakage are likely to occur. Furthermore, there is a method of increasing the amount of wax in the coating film to improve the slipperiness of the coating film surface to improve the moldability and scratch resistance. It was confirmed that the moldability could be improved to some extent just by increasing the amount, but the scratchability was insufficient.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a coating and a coated metal plate having excellent formability and scratch resistance.

[0005]

According to the present invention, at least one kind of wax having a melting point of a wax contained in an organic or inorganic film formed on a metal plate is higher or lower than a mold temperature at the time of molding. The mixed organic or inorganic coating on each side or one side of the metal plate is 0.1 μm or more, 300 μm or more.
It is a coated metal plate excellent in scratch resistance and formability, which is characterized by being applied in a thickness of not more than μm.

The present invention will be described in detail below. As the wax contained in the organic or inorganic film, at least one wax having a melting point lower than the mold temperature during molding was mixed with at least one wax having a melting point lower than the mold temperature during molding. By covering the surface of the coating, adhesion between the mold and coating is less likely to occur, and there is an effect of preventing scratches. In addition, wax with a melting point higher than the mold temperature is present as a solid in the film during molding, and even if partial adhesion between the mold and the film occurs, it exerts a lubricating effect, causing damage and adhesion of the film. This is because it has the effect of preventing an increase in the friction coefficient due to and improving the formability. The effects of these two types of wax are compatible with the scratch resistance and the moldability.

The resin used for the organic coating layer is thermoplastic,
It may be thermosetting, and specifically, polyester resin, fluorine resin, epoxy resin, acrylic resin, urethane resin, silicon resin, olefin resin, butyral resin, vinyl chloride resin, etc. , Engineering plastics such as polyether sulfone resin, polyphenylene sulfide resin, etc.,
These may be used alone or in combination. Further, an inorganic polymer such as siloxane or borosiloxane may be used, and an organic / inorganic mixture or a composite may be used.

Pigments may be added to the coating layer, and specifically, commonly used pigments such as color pigments, rust preventive Pigs, constitution Pigs, and metal powders may be used. Further, additives may be added, and specifically, leveling agents, defoaming agents, color separation preventing agents and the like. The method for forming the coating may be painting, or a previously formed coating such as a film may be attached.

As the wax, an organic wax is used. Synthetic wax such as olefin and acrylic
It is desirable that a natural wax such as carnauba-based wax or a mixture thereof is contained in the coating film in an amount of 0.01% or more and 10% or less. The wax content is set to 0.01% or more in order to ensure lubricity and scratch resistance. In addition, the reason why the wax content is 10% or less is that
This is because if it is more than 10%, appearance defects such as uneven gloss are caused.

The thickness of the coating layer is set to 0.1 μm or more because if it is thinner than 0.1 μm, the lubricity deteriorates. The film thickness is set to 300 μm or less because if it is thicker than 300 μm, the formability of the steel sheet is impaired. The coating film may be applied to the front and back of the metal plate or may be applied to only one side. Here, the metal plate on which the organic film is applied is
It includes not only steel sheet materials such as cold rolled steel sheets and plated steel sheets but also aluminum alloy sheets, Ti alloy sheets, copper alloy sheets and the like.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As the original plate of the coated metal sheet, not only cold rolled steel sheet, plated steel sheet, steel sheet material such as tin plate but also aluminum alloy sheet, Ti alloy sheet, copper alloy sheet, etc. may be used. It is good, but in this example, cold rolling steel sheet and galvanized steel sheet were used. Regarding the method of coating the metal plate, it is by painting (painted metal plate),
It was manufactured in two ways, that is, the one to which the film is attached (laminated metal plate). In the method for producing a coated metal plate, a coating type chromate treatment was applied to the metal plate, various paints were coated with a roll coater to a predetermined film thickness, and baked in an oven. The baking conditions were in accordance with the standard specifications of each paint.

The method for producing a laminated metal plate is as follows. After applying the coating type chromate treatment on the metal plate, an adhesive suitable for each film is applied by a roll coater to a predetermined film thickness, and the solvent is heated in an oven. After volatilization, each film was attached with a laminator and baked in an oven to cure the adhesive. As the type of wax to be used, any of olefin-based, acrylic-based synthetic wax, carnauba-based natural wax, and a mixture thereof may be used. Among them, the acrylic wax is used. . The content of wax in the coating film was 5%.

The scratch resistance was evaluated by a flat plate sliding tester shown in FIG. Test plate temperature and sliding chip temperature are room temperature (about 20 ℃), 40 ℃, 60 ℃, 80 ℃, 100 ℃
The sliding tip is pressed onto the fixed test piece with a load (P) of 50 kgf, and the speed is 15 without lubrication.
It was slid at 0 mm / s for 100 mm, and the scratched condition of the coating film surface was visually evaluated. As an index for visual evaluation, ∘ without scratches, △ with slight scratches, and × with severe scratches
And Table 1 shows the characteristic values of the original metal plate as the test material,
The results of visual evaluation are summarized in Table 2.

Further, as an evaluation of formability, cylindrical deep drawing was performed using the materials shown in Table 1. A tester manufactured by Erichsen Co., Ltd. of Germany was used, and a flat bottom punch of 50φ was used for forming at a forming speed of 2 mm / s, a wrinkle holding force of 0.5 ton, and a blank size of the test material was 100φ. The clearance between the punch and die is just the thickness of the metal plate (0.6
mm) and molding was performed at a molding die temperature of 60 ° C. As an index of moldability, the maximum loads during molding were compared. Fig. 2 shows a conceptual diagram of the maximum load, Table 3 shows the test materials, and Fig. 3 shows the results of deep drawability evaluation.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

As described above, at least one kind of wax having a melting point of the wax in the coating film within the scope of the present invention is higher or lower than the mold temperature at the time of molding is mixed, and the coating film is coated on both sides of the metal plate or By applying 0.1 m or more and 100 μm or less on one surface, it is possible to provide a coated steel sheet having excellent scratch resistance as shown in Table 2 and excellent formability with low deep drawing load as shown in FIG.

[0019]

As described above, by using the coated steel sheet of the present invention which is excellent in scratch resistance and formability, it is possible to improve the mold maintenance and the mold which were performed for preventing scratches during forming. It is possible to omit special plating, etc., and to manufacture products with higher quality and high productivity of coated steel sheets.

[Brief description of drawings]

FIG. 1 is a schematic view of a flat plate sliding tester.

FIG. 2 is a conceptual diagram of a maximum load in a deep drawing test.

FIG. 3 is a diagram showing the results of a deep drawing forming test.

[Explanation of symbols]

 1 Sliding tip 2 Test piece (plate) 3 Test piece fixing base (sliding base)

Claims (2)

[Claims] 1. At least one kind of wax having a melting point higher or lower than the mold temperature at the time of molding is mixed in each wax contained in an organic or inorganic film formed on a metal plate. A coated metal plate with excellent scratch resistance and moldability. 2. A coating excellent in scratch resistance and formability according to claim 1, wherein the organic or inorganic coating layer on both sides or one side of the metal plate is 0.1 μm or more and 300 μm or less. Metal plate.