JPH1066931A - Method for producing coated metal sheet having sharpness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a coated metallic sheet having image clarity without changing the number of bakings by applying a baking-type org. coating material on at least one side of a metallic sheet, applying a soln. contg. clear resin in a specified weight ratio and baking the paint at a specified temp. SOLUTION: A urethan coating material is applied on a galvanized steel sheet chromated by coating and baked. A polymerized polyester coating material is applied thereon as an overcoat and further a methyl ethyl ketone soln. contg. 0.04-80.00wt.% clear resin identical with the resin of the overcoat is applied thereon at 10.0g/m<2> . The coating material is baked at the maximum baked sheet temp. between 150 and 300 deg.C by high-frequency induction heating. The coated metallic sheet has the image clarity equivalent to >=0.6 times the standard value when tested by a portable definition glossmeter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a coated metal sheet having sharpness and used for home appliances, building materials, automobiles and the like.

[0002]

2. Description of the Related Art When a design is imparted to a coated metal plate, the one that appeals to human vision most is sharpness. When applying a design to a painted metal plate, metallic powder, mica powder, aggregate, etc. are added to the paint to express a metallic feeling, pearly feeling, peel skin, etc., but these solid components were added to the paint. In such a case, it is known that the surface gloss decreases as the amount of addition increases. At the same time, the sharpness on the coating film surface also decreases,
The effect of the metallic feeling is also reduced by half.

[0003]

In order to solve this problem, it is effective to provide another clear layer on a layer having a design such as metallic. However, if the paint is applied again from the normal paint specifications, it is necessary to perform the firing step once more times than usual,
There are many negative factors, such as an increase in operating costs and performance degradation due to the heat load of the undercoat.

Accordingly, an object of the present invention is to provide a method for producing a coated metal sheet having sharpness by providing a clear layer on the outermost layer of a coating film while performing the usual number of firing steps.

[0005]

According to the present invention, a baking type organic paint is applied to at least one side of a metal plate, and a solution containing 0.04 to 80.00% by weight of a clear resin is coated thereon. After coating on the surface, baking is performed at a maximum baking plate temperature of 150 ° C. or more and less than 300 ° C. Further, the present invention is characterized in that a chemical conversion treatment and an undercoating are applied in order from the bottom between the metal plate and the layer of the organic paint.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for producing a coated metal sheet according to the present invention will be described. Examples of the metal plate in 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.

[0007] The metal plate can be subjected to a pretreatment as required. Examples of the pretreatment include water washing, hot water washing, pickling, alkali degreasing, grinding, polishing, chromate treatment, zinc phosphate treatment, composite oxide film treatment, and the like, and these are used alone or in combination to perform the coating pretreatment. The conditions for the pre-coating treatment may be appropriately selected.

Next, if necessary, an undercoat paint is applied on a metal plate and cured and dried to form an undercoat film layer. Examples of the undercoat paint include polyester paints, epoxy paints, urethane paints and the like, and any paint paints generally used may be used. This is coated with a roll coater, curtain flow coater, roller curtain coater, electrostatic coating machine, brush, blade coater, die coater, etc. to a required film thickness, and then left at room temperature or a hot air oven, an induction heating furnace, Near infrared furnace,
An undercoat film layer is obtained by curing and drying in a far-infrared oven, energy ray curing oven, or the like. The film thickness is arbitrary, but about 1 to 30 μm, particularly 3 to
A dry film thickness of about 12 μm is common. Although the maximum attained plate temperature (PMT) is not particularly specified,
Generally, about 0 ° C to 260 ° C.

If necessary, a baking type organic paint is applied after the above-mentioned pretreatment or further formation of an undercoat film. As organic paints, polyester, epoxy,
There are urethane-based and acrylic-based paints, and any baking type paint-based paint can be used. This is applied to the required thickness by the same method as the undercoating film described above. The film thickness is optional, but is preferably 5 to 20
μm. If necessary, pigments and aggregates, surface-decorated metal powders and glass powders, design powders such as pearl and mica, leveling agents and dispersing resins, matting silica and surfactants, diluting solvents, etc. May be contained in the paint.

Next, a solution containing a clear resin is applied on the metal plate to which the organic paint has been applied. As the type of the solvent to be used, polar solvents such as water and dimethylbenzenesulfonic acid, low-boiling solvents such as lower alcohols and ketones, high-boiling solvents such as isophorone and benzyl alcohol, and mixed solvents thereof can be used. . Moreover, as the clear resin, a polyester resin, an acrylic resin, an epoxy resin, a fluororesin, a silicone resin or the like alone or a copolymer resin thereof can be used. Further, a melamine alkyd resin, a urethane resin, an isocyanate resin, or the like may be used in combination in order to accelerate the curing of the added resin.

It is necessary that the added amount of these resins is 0.04 to 80.00% by weight in the solution.
If it is less than 0.04%, the clear layer will not be formed uniformly and no clear image will be obtained. The coating amount of the solution is not particularly limited, but by setting the coating amount to 0.2 to 25.0 g / m ² , a coated metal plate having a good appearance can be obtained. As for the method of applying the solution, a general sprayer, a coater or the like may be used. Specifically, spraying, sprinklers, continuous spraying equipment, zapping tumblers, curtain coaters,
Roller curtain coater, flow coater, laminar flow and the like. At the same time, spraying by heating of a steam generator or the like, or spraying, extrusion or foaming using an external gas pressure such as air blowing may be used.

Finally, the coating film is fired. As the baking method, the same method as that for the undercoat film described above can be used. At that time, the PMT is set to 150 ° C. or more and less than 300 ° C. If the PMT is lower than 150 ° C., the coating film is insufficiently fired. If the PMT is higher than 300 ° C., the organic resin component of the paint starts to thermally degrade, and the object of the present invention cannot be achieved.

According to the method of the present invention, since the firing step of the organic paint and the clear paint can be performed only once, a coating metal having sharpness without reducing operating costs and causing thermal deterioration of the undercoat film. Boards can be manufactured.

[0014]

【Example】

(Example 1) A method for manufacturing a coated metal sheet according to the present invention will be described with reference to examples. An urethane-based paint (FL) is used as an undercoat on a hot-dip galvanized steel sheet that has been subjected to a coating type chromate treatment.
C600 / Nippon Paint Co., Ltd.) with a thickness of 5 μm using a bar coater, and PMT215 by a high frequency induction heating method.
It was baked so that it might become ℃. On top of this, a polymerized polyester-based paint (FLC200HQ /
Nippon Paint Co., Ltd.) was applied using a bar coater so that the dry film thickness became 15 μm. Using a curtain flow coater, apply the same resin (FLC2
A methyl ethyl ketone solution containing the clear resin (00HQ) in an amount shown in Table 1 was applied so that the application amount was 10.0 g / m ² . Next, Table 1 was obtained by the high-frequency induction heating method.
Baked with PMT.

With respect to the obtained coated metal plate, a measurement value (Gd value) of a sharpness was measured with a portable definition gloss meter (PGD meter). Those having a Gd value of 0.6 or more were judged to be acceptable. As is clear from the measurement results shown in Table 1, a coated metal plate having sharpness was able to be obtained by the production method of the present invention.

[0016]

[Table 1]

(Example 2) On a hot-dip galvanized steel sheet subjected to a coating type chromate treatment, a urethane-based paint (FLC600 / manufactured by Nippon Paint Co., Ltd.) of 5 μm as an undercoat paint,
It was applied using a bar coater and baked at a PMT of 215 ° C. by a high frequency induction heating method. On top of that, as a top coat, polymerized polyester paint (FLC
3510 / Nippon Paint Co.) was applied using a bar coater so that the dry film thickness became 15 μm. From above, the solution was applied using a sprinkler, and the applied amount was 14.0 g / m ^2.
It applied so that it might become. As the solution, a polyester resin paint (FLC1) having a higher molecular weight than the top coat paint was used.
80 / Nippon Paint Co., Ltd.) in an amount shown in Table 2. Next, it was baked with the PMT shown in Table 2 by a high frequency induction heating method.

With respect to the obtained coated metal plate, a measurement value (Gd value) of the sharpness was measured by a portable clarity gloss meter (PGD meter). Those having a Gd value of 0.6 or more were judged to be acceptable. As is clear from the measurement results shown in Table 2, a coated metal plate having sharpness was able to be obtained by the production method of the present invention.

[0019]

[Table 2]

According to the production method of the present invention, the clear coating film does not need to be fired separately from the top coating material as in the prior art, and can be simultaneously produced. Board can be manufactured.

[0021]

According to the production method of the present invention, a solution containing a clear resin is applied before firing an organic paint, and then baked in a predetermined temperature range, thereby eliminating the need for a plurality of firing steps. A coated metal plate having a clear layer on the surface can be obtained. By applying this to the home electric appliance field and the like, it is possible to obtain an inexpensive product having high productivity.

Claims (2)

[Claims] 1. A baking type organic paint is applied to at least one side of a metal plate, and a clear resin is added on the organic paint in a weight ratio of 0.0
After applying a solution containing 4 to 80.00% on the coating surface,
A method for producing a coated metal sheet having sharpness, characterized in that the sheet is baked at a maximum baked sheet temperature of 150 ° C. or more and less than 300 ° C. 2. The clarity of claim 1, wherein a chemical conversion treatment and an undercoating are applied in order from the bottom between the metal plate and the organic paint layer in the configuration of the coated metal plate. A method for producing a coated metal sheet.