JPS5816945B2 - Metallic painting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metallic coating method and a water-based metallic paint used therein, and more specifically, the present invention relates to a metallic coating method and a water-based metallic paint used therein. To provide a metallic coating method in which a paint is applied as a base coat and a clear top coat mainly composed of a polyurethane resin, which has hardly been used in metallic coatings, is dried and cured, and a water-based metallic paint used therein.

Conventionally, metallic coatings used for automobiles, etc.
This is mainly done by applying an oil-based varnish containing 20 to 25 parts by weight of aluminum powder as aluminum paint. When applied, the aluminum powder leaf-rings and exhibits light reflecting ability, giving it excellent gloss and Due to the nature of oil-based paint, it has the characteristics of producing an elegant paint film with a metallic luster that is durable, rust-proof, anti-corrosive, and moisture-resistant, and the amount of paint used is currently enormous. .

The vehicle used in this case is usually an oil-based solvent-based liquid paint in which a thermosetting resin such as phenol resin, styrene resin, acrylic resin, epoxy resin, or polyester resin is dissolved in an organic solvent.

However, many of these organic solvents are harmful and dangerous due to their flammability, and their use requires special care and is also expensive.

The present invention is based on the use of a powdery water-based paint instead of such a harmful and dangerous oil-based solvent-based liquid paint.

In other words, by using water-based water-based paints that are water-soluble or water-emulsifiable powders that have good storage stability, they can be used as an aqueous solution or an emulsion by dispersing them in water at the time of use, so there is no harm or danger associated with the use of conventional solvents. It is possible to eliminate all disadvantages such as quality and price.

Powdered water-based paints have conventionally been used in large quantities as interior coatings for buildings and as water-soluble electrodeposition paints as undercoats for automobiles, etc., but there have been no examples of them being used as base coats for Citalink coatings.

The present invention aims to utilize such a water-based paint for metallic painting, and for this purpose, provides a new water-based paint for metallic painting and a metallic painting method using the water-based paint as a base coat. It is something.

That is, powdered water-based paints are easy to store and are non-polluting paints, making it possible to eliminate the above-mentioned drawbacks.

Its composition includes metallic powder, a glass hollow body, a rust preventive agent, and a coloring pigment mixed for color matching if necessary, and a powder mixture containing a water-soluble resin or a water-emulsifiable resin. The viscosity is adjusted to the appropriate viscosity for application.

The present invention will be explained in detail below.

In addition to aluminum powder, which is generally used as metallic powder, copper powder, mica powder, mica powder coated with titanium oxide, etc. are used, and mica is an aluminosilicate containing an alkali metal, such as muscovite, biotite, and lepidolite. Among them, muscovite has a particularly strong birefringence and has metallic or pearl-like luster even though it is a non-metallic powder, and is preferably used because of its low price.

In addition, metallic powder, like conventional powders, depends on its particle size: type 1 (specular reflectance is high and reflects heat rays and prevents internal temperature rise), type 2 (specular reflectance is intermediate, with a certain degree of specular reflection) and diffuse reflectance) and type 3 (
Three types can be selected and used as raw materials for metallic base coats.

The glass hollow bodies used are those called glass microballoons, shirasu balloons, or microspheres, which are commonly used outside of metallic coatings, and the glass microballoons are made of sodium silicate,
It is made into a hollow body by co-firing borax and a foaming agent, etc., and is made into a hollow body. Shirasu balloons are made by heating and ballooning sized volcanic eruption shirasu and can be obtained at a relatively low cost.

The outer shell of these is composed of inorganic silicate, and although the density is thick, the bulk specific gravity is about 0.05 to 5 as a hollow body.
The particle size is as small as 0.2 and the particle size is relatively uniform between 50 and 500 mm.

In addition to the above-mentioned characteristics, these hollow bodies have a wall thickness of 1~
10 pm1 true specific gravity 0.08-0.5, melting point 450-1
It has a compressive strength of 100 to 200 kg/ff1 (static pressure 50% breaking) at 300℃, and as a low-density filler, it reduces the density of painted products and causes flow-out like other light fillers with excellent thixotropy. It prevents the paint surface from sagging, enables heavy coating of 60 to 100 μm in one coat, and imparts various properties such as reducing the weight of the paint film and increasing impact resistance. can.

As a rust preventive agent, white products such as aluminum phosphate and molybdenum white are preferred, but depending on the purpose, colored strontium chromate, zinc chromate, red iron oxide, etc. may also be used, and the process of applying other anticorrosive paints as a base coat can be omitted. You can.

In addition, as coloring pigments, general pigments such as white, titanium oxide, lithopone, carbon black for black, red red (red), yellow lead (vermilion yellow), chromium verdigris (green), manganese violet (purple), etc. can be used. , it is possible to maintain color with a formulation that matches the final color tone.

Water-soluble or water-emulsifiable resins include glue compounds such as casein soda and dextrin, powders of water-soluble polymer compounds such as polyvinyl alcohol, methyl cellulose, hydroxymethyl cellulose, and polyvinyl pyrrolidone, and polycarboxylic acid resins. Synthetic resin powder for electrodeposition coating using an alkali hydroxide as a neutralizing agent, or emulsifiable resin powder obtained by force drying a polyvinyl acetate or polyacrylic vinyl acetate copolymer emulsion can be used.

As mentioned above, powder water-based paints use water as a dispersion medium without using organic solvents, so they are non-polluting and pose no risk of fire, and do not require special large equipment for application and spraying.
Although it has an unnecessary characteristic, the evaporation rate of water is slow and the paint may sag, but this can be prevented from developing by the action of the glass hollow body used at the same time.

Base coats made of such compositions can be obtained relatively economically, and because color matching can be done with colored pigments at this stage, the base coats have better corrosion resistance and stability than conventional colored top coats. is obtained.

Furthermore, the clear polyurethane paint used as the top coat has unique durability among other synthetic resin paints, and is in increasing demand as a maintenance-free paint.

In general, paints whose resin is a reaction compound of polyvinyl acetate and polyol are classified into the following five types.

In other words, there are oil-modified polyurethanes (urethanized oils), moisture-curing polyurethanes, block polyurethanes, catalyst-curing polyurethanes, and polyol-curing polyurethanes. It is a polyurethane paint.

Any of the above types of polyurethane paints may be used as a top coat, but its overall advantage is that even when dried at room temperature, the film has the same or better elasticity, abrasion resistance, weather resistance, and resistance than other baking paints. Excellent solvent resistance, chemical resistance, flame resistance, gloss and electrical properties.

Since a polyurethane paint having such various properties is used as a top coat, it is possible to obtain a metallic paint surface that is more robust than the top coat paint surface of other conventional resin paints.

Examples of paint compositions according to the present invention and metallic coatings using them will be shown below.

(1) Composition of Base Coat A Water-based powder base coat A was prepared using methyl cellulose with the following formulation.

(Weight) Methyl cellulose (manufactured by Shin-Etsu Chemical) 2 parts Aluminum powder (manufactured by Toyo Aluminum) 5 parts Carbon black (manufactured by Mitsubishi Chemical Corporation) 0.005 parts Glass hollow body (manufactured by Philadelphia Quartz) 2 parts Phosphorus Aluminum acid (manufactured by Teikoku Kako ■) 1 part ABS surfactant (manufactured by Daiichi Kogyo Seiyaku ■) 0.5 parts (2) Composition of Baseco-1-B Using vinyl acetate copolymerized re-emulsified powder resin, water-based with the following formulation. Powder base coat B was created.

Circulated vinyl acetate copolymer powder (manufactured by KIST Synthetic Chemical Industry ■) 5 parts mica powder (manufactured by square hole fish scale foil ■) 5 parts organic yellow pigment (manufactured by Mitsubishi Chemical Industries ■) 0.01 part glass hollow body (
Same as A) 1 part aluminum phosphate (A
When using 1 part polyvinyl alcohol (manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.5 parts, the above powder coating is used by dispersing it in 50 parts of water.

(3) Top coat 2-component polyurethane paint Byrock (manufactured by Rock Paint Co., Ltd.: auto clear and non-yellowing hardening agent) was used.

It was used after adjusting the viscosity to 15 seconds (horde cup A4, 20° C.) with a mixed diluent at a base resin to curing agent ratio of 4:1.

The base coats A and B were coated on separate steel plates (0.8X1
0XI 5cm), dried at 100° C. for 30 minutes, cooled in air, and then sprayed with the above top coat.

Table 1 shows the test results for the coating film of the test piece that was dried at 70° C. for 20 minutes and cooled in the air.

Claims (1)

[Scope of Claims] 1 Metallic powder, glass hollow body and rust preventive agent, or coloring pigments are mixed together with these, and a powdered water-based paint containing a water-soluble or water-emulsifiable resin as a main component is applied as a base coat and dried. A metallic coating method, which is characterized in that a clear top coat containing a polyurethane resin as a main component is then applied to the painted surface, dried and cured. 2. Claim 1, wherein the powdered water-based paint is a water-based paint containing a metallic powder, a glass hollow body, a rust preventive agent, or a colored pigment together with these and further comprising a water-soluble or water-emulsifiable resin as a main component. Metallic painting method described.