JPH1016134A - Coated metal plate excellent in resistance to dirt pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the electrification of static electricity as the main cause of dirt pickup from developing so as to allow to suppress the dirt picking-up phenomenon due to static electricity by a method wherein the specified weight percentage in a dry coating film of fluoric compound is included in an organic coating film as the top coating of a metal plate. SOLUTION: On at least one side of a metal plate, a chemical conversion treatment and an undercoating are applied. Then, on its resultant side, an organic coating film, in which 0.3-8wt.% in a dry coating film of fluoric compound is included, is applied as a top coating. The undercoating is provided on the chemical conversion treatment applied on the alloy plate. As the coating material used for the undercoating, polyester-based one, acrylic one, polyurethane-based one, epoxy-based one, their respective modified bodies and their mixtures are exampled and there is no special limitation as coating material as long as coating material used for ordinary solvent-based PCM is concerned. As the fluoric compound coating in the organic coating film, tetrafluoroethylene resin, tetrafluoroethylne-propylene hexafluoride copolymer resin or the like is used.

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 having a function of suppressing a dusting phenomenon caused by static electricity generated when a coating film surface comes into contact with a different material, and having excellent dust resistance. . INDUSTRIAL APPLICABILITY The coated metal sheet of the present invention is suitable for home appliances and interior building materials, and can also be used as an outer panel for equipment.

[0002]

2. Description of the Related Art In a field where thin plate parts are used in a housing of a refrigerator or the like, a precoated steel plate (PCM) has been used for a long time. One of the problems is a dusting phenomenon at the time of processing. Specifically, at the time of forming a pre-coated steel sheet, static electricity is generated due to dissimilar material contact or rubbing on the surface of the coating film, and dust and metal powder floating and scattering around the workplace due to charging adhere to the pre-coated surface This is a phenomenon that adversely affects the subsequent forming process and assembling process such as flaws.

[0003]

As countermeasures against dust, there are grounding of a pre-coat and installation of a static eliminator such as an ion shower. It has little effect on static elimination and has not yet completely solved the problem. In view of the above, the present invention provides a coated metal plate that is excellent in dust resistance, in which charging due to static electricity, which is a main cause of dust, is prevented to prevent dust caused by static electricity.

[0004]

Means for Solving the Problems The inventors of the present invention have analyzed the dusting phenomenon due to electrification, and found that a fluorine compound which is the substance having the lowest electrification sequence is contained in the overcoat film.
The pre-coat coating lowers the charged potential of the whole coating film, and by generating a negative charge when contacting or rubbing with a different material, not only prevents the generation of static electricity, but also reduces the potential generated on the surface layer of the coating film. By making the direction
It has been found that adsorption of dust mainly composed of carbon, plated iron and zinc powder can be prevented. The coated metal plate of the present invention is based on the above findings, and is provided with a chemical conversion treatment and an undercoat on at least one side of the metal plate, and then a fluorine compound is dried and coated on the organic coating as an overcoat. It is characterized by containing 0.3% to 8% by weight to the membrane.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. First, examples of the metal plate used for the coated metal plate of the present invention include a steel plate, an aluminum plate, a stainless steel plate, a titanium plate, and a copper plate. Examples of steel sheets include cold-rolled steel sheets, hot-rolled steel sheets, galvanized steel sheets, galvannealed steel sheets, zinc-iron alloy-coated steel sheets, zinc-aluminum alloy-coated steel sheets, aluminum-coated steel sheets, chromium-coated steel sheets, and nickel-plated steel sheets. , A zinc-nickel alloy-plated steel sheet, a tin-plated steel sheet, and the like. First, a chemical conversion treatment is provided on at least one surface of the alloy plate. The chemical conversion treatment includes a chromate treatment, a zinc phosphate treatment, a composite oxide film treatment and the like, and these may be used alone or in combination. These conditions may be appropriately selected.

Next, an undercoat is provided on the chemical conversion treatment. The paint used for the undercoat is polyester-based, acrylic-based, polyurethane-based, epoxy-based, or a modified product of each, and a mixture of each other, and is usually used for a solvent-based PCM paint. There is no particular limitation. The thickness of the undercoat film is not particularly limited.
A thickness of not less than μm and less than 10 μm is generally used as a coated metal plate. After the application, it is baked at 150 ° C. or more and less than 300 ° C., and is cured and dried. If the baking temperature is lower than 150 ° C., the adhesiveness is insufficient, and if it is higher than 300 ° C., the resin component is thermally degraded and the workability is deteriorated.

Further, on the undercoat, there is provided an overcoat layer containing 0.3 to 8% of a fluorine compound in the organic coating film. Although not essential, additives such as pigments, surface-modified metal powders and glass powders, dispersants, leveling agents, waxes, aggregates, and the like, and diluent solvents required for painting may be contained. The organic resin used for the overcoat is polyester, polyacryl, polyurethane or vinylidene fluoride, each modified product, and a mixture of each other, and is usually used for a solvent-based paint for PCM. It is not particularly limited as long as it is one.

As the curing agent used for forming the thermosetting resin film layer by the reaction with the organic resin, amino resins such as melamine resin, urea resin and benzoguanamine resin, or isocyanate compounds and blocks thereof Is preferred. As the fluorine compound to be contained in the organic coating film, tetrafluoroethylene resin (PTFE)
Fluorinated ethylene resin such as fluorinated ethylene / hexafluoropropylene copolymer resin (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin (PFA) Fluorinated organic acids which are liquid at normal temperature, such as octanoic acid (PFOA).

It is essential that the content of the fluorine compound is 0.3 to 8% by weight in the dried coating film of the top coat. If it is less than 0.3%, the effect of lowering the charging sequence does not appear, and the dust resistance decreases. When the content is 8% or more, the fluorine component is liberated from the components of the top coating at the time of coating, and the appearance of the coating is impaired. The method of mixing the fluorine compound into the paint is not particularly limited, and a usual pigment dispersion method may be used. Specifically, ball mill, viscometer, stirring by hand, shaking stirring, screw stirring and the like. In the case of using a fluorinated ethylene-based resin, the particle size, shape and molecular weight thereof are not particularly limited, but those having an average particle size of 0.1 to 30 μm are preferable from the viewpoint of coating appearance. Furthermore, when a fluorinated organic acid is used, the modification of the functional group at the end thereof may be left open, an alkali metal salt, or an ester with another organic alcohol.

The thickness of the top coat is not particularly limited.
A coating metal plate having a thickness of 0 μm or more and less than 20 μm is generally used. After the application, it is baked at 150 ° C. or more and less than 300 ° C., and is cured and dried. If the baking temperature is lower than 150 ° C., the hardness and solvent resistance of the coating film are inferior. If the baking temperature is higher than 300 ° C., the resin component deteriorates due to heat and the workability is deteriorated. As a method of applying the undercoat or the overcoat, or a method of curing and drying, a coating and baking method using a general solvent-based paint can be used. As an example, as a coating method,
Roll coaters, roller curtain coaters, curtain flow coaters, electrostatic coating machines, brushes, blade coaters, die coaters and the like can be used. As a curing and drying method, a hot air oven, an induction heating oven, a near-infrared oven, a far-infrared oven, an energy ray curing oven, standing at room temperature, and the like can be used.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the coated metal plate of the present invention will be described. A hot-dip galvanized steel sheet subjected to chromate treatment after alkali degreasing was used as a substrate. As an undercoat, FLC641 made by Nippon Paint, which is a urethane-based paint, is applied using a bar coater so as to have a dry film thickness of 4 μm, and a high frequency induction furnace is used at a maximum ultimate plate temperature (hereinafter referred to as PMT) of 215 ° C. And baked. Next, as a top coat, FLC3510H manufactured by Nippon Paint, which is a polyester / melamine-based paint, was used, and after adding the fluorine compounds shown in Table 1, it was applied in the same manner as undercoating at a dry film thickness of 15 μm and a PMT of 230 ° C. . Then, the dust resistance of the obtained coated plate was evaluated.

The dust resistance was evaluated by an ash method using dust mainly composed of carbon, iron, and zinc powder collected from an assembly work site. Specifically, after the coating film surface is rubbed and brought into contact with a portion that actually contacts in the assembly line, such as a transport roll or a holding part for piling, the dust is sprinkled on the coating film surface, and a blower such as a dryer is used. After the dust was shaken off, the remaining state of the dust was visually determined.
The evaluation of the remaining dust was as follows: ：: no residue, Δ: slight residue, ×: significant residue, and 合格 was passed.

The evaluation of the charging train was also performed by the following method. Scratching the coating surface to the actual contact area
After the contact, the surface of the coating film was positively charged, and whether or not the film surface was negatively charged was measured using a static electricity measuring device manufactured by SIMCO Japan. In this case, the more negatively charged, the better the dust resistance. Table 1 shows the evaluation results of the dust resistance and the charging sequence. As is clear from Table 1, the product of the present invention in which an appropriate amount of a fluorine compound is contained in the overcoat film is negatively charged and has excellent dust resistance.
In addition, although the example of this invention is a result using the hot-dip galvanized steel plate as a base material, the same result was obtained also when using another metal plate as a base material.

[0014]

[Table 1]

[0015]

According to the present invention, the coated metal sheet provided with the undercoat and the overcoat has a fluorine compound in the organic coating of the topcoat in a weight ratio of 0.3% to 8% with respect to the dry coating. Since it contains, it has excellent dust resistance. Therefore,
When applied to the home appliance field, dust is not adsorbed at the time of work, so that product yield is improved and work efficiency is improved.
Furthermore, a product with good appearance quality can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyasu Furukawa 1 Kimitsu, Kimitsu City, Chiba Prefecture Nippon Steel Corporation Kimitsu Works

Claims (3)

[Claims] At least one surface of a metal plate is subjected to a chemical conversion treatment and an undercoat, and then a fluorine compound is added as an overcoat to an organic coating film in an organic coating film in a weight ratio of 0.3% to 8% with respect to the dry coating film. Painted metal sheet with excellent dust resistance, characterized by containing. 2. The coated metal sheet according to claim 1, wherein the fluorine compound comprises a fluorinated ethylene resin. 3. The coated metal sheet according to claim 1, wherein the fluorine compound comprises a fluorinated organic acid.