Coating processes – Solid particles or fibers applied – Applying superposed diverse coatings or coating a coated base
Reexamination Certificate
1999-12-07
2001-12-18
Parker, Fred J. (Department: 1762)
Coating processes
Solid particles or fibers applied
Applying superposed diverse coatings or coating a coated base
C427S470000, C427S486000, C427S203000, C427S205000, C427S404000, C427S421100, C106S403000, C106S404000
Reexamination Certificate
active
06331326
ABSTRACT:
FIELD OF THE TECHNIQUE
The present invention relates to a method for forming a coating film exhibiting an appearance of plated metal and to a coating composition adapted for forming a coating film exhibiting a plated metal-resembling appearance.
BACKGROUND OF THE TECHNIQUE
There has been used a coating composition comprising an aluminum flake pigment having flake thicknesses in the range of 0.1-1 &mgr;m and an average particle size of 5-60 &mgr;m, which has been treated by grinding in a ball mill together with a fatty acid, for providing the coating film with a brilliant appearance.
The aluminum flakes to be blended in the metallic paints as a brightening pigment are classified according to their properties into a leafing type and a non-leafing type. The leafing type aluminum flake pigment is available usually in a state in which the flakes are treated by grinding them together with stearic acid. Due to a reduced interfacial tension, this pigment is liable to float up onto an upper layer of the metallic coating film when being coated and to form a structured coating layer in which the flakes align over one another in parallel to the substrate, resulting in an appearance of successive aluminum layers. However, the aluminum flake pigment which has floated up on the top face of the upper layer is not fixed in the coating film after the coating film cures, so that the flakes may easily be peeled off by touch. On the other hand, when a clear coating is applied onto an uncured coating film in a wet-on-wet technique, the orientation of the aluminum flakes is disturbed and the appearance deteriorates. When a clear coating is applied onto the metallic coating film after the film has been heat-cured, a reliable adhesion of the coated film and the clear coating layer will not be guaranteed.
For these reasons, the practice has been to use principally the latter, i.e. non-leafing type aluminum flakes in industrial paints.
In conventional metallic paints containing only non-leafing type aluminum flakes, these flakes are usually contained therein after having been ground together with oleic acid, whereby a problem is brought about in that the aluminum flakes added as a brightening pigment have a larger thickness and may be dispersed within the metallic coating layer upon its application on a substrate, so that each aluminum flake is visually recognizable as a discreet particle and a plated metal-like appearance of the coating is not attained, though the adhesion of the metallic coating to the layer of the clear coating is better.
As a coating composition in which the problem of appearance of a metallic coating is improved, there has been proposed in Japanese Patent Kokai Sho-53-9836 A a coating composition characterized in that it comprises a volatile carrier, fine metal particles and a binding material, wherein the fine metal particles consist of metal platelets having thicknesses not greater than 1,000 Å shaped generally irregularly and present in such an amount that the weight ratio of the binding material to the metal platelets is in the range from 0.05/1 to 10/1. This metallic coating composition is, however, inferior in hiding power for hiding sand scratches on the substrate and does not permit the formation of a coating film exhibiting a superior continuous plated metal-like appearance in a stable manner.
An object of the present invention is to provide a method for forming a coating film, in which a coating film having no problems in its properties and which is superior not only in its hiding power for hiding sand scratches on the substrate but also in a continuous plated metal-like appearance can be built up in a stable manner.
Another object of the present invention is to provide a coating composition which can be applied by the method for forming a coating film as above and form a coating film having satisfactory film properties and which is superior not only in its hiding power for hiding sand scratches on the substrate but also in that a continuous plated metal-like appearance can be built up in a stable manner.
DISCLOSURE OF THE INVENTION
The present invention consists of the following methods for forming a coating film and a coating composition:
(1) A method for forming a coating film on a substrate comprising
applying onto the substrate a primer (A) and/or a first metallic paint (B) containing non-leafing type aluminum flakes (a) having thicknesses in the range from 0.1 to 1 &mgr;m and an average particle size in the range from 1 to 60 &mgr;m and, then, applying thereonto a second metallic paint (C) containing small thin metal flakes (b) having thicknesses not greater than 0.08 &mgr;m and an average particle size in the range from 5 to 40 &mgr;m.
(2) The method as defined in the above (1), wherein the primer (A) and/or the first metallic paint (B) and the second metallic paint (C) are applied sequentially on the substrate by a wet-on-wet technique.
(3) The method as defined in the above (1), wherein a heating step is incorporated after the application of the primer (A) and/or the first metallic paint (B), whereupon the second metallic paint (C) is applied thereonto.
(4) A method for forming a coating film on a substrate comprising
applying onto the substrate a primer (A) and/or a first metallic paint (B) containing non-leafing type aluminum flakes (a) having thicknesses in the range from 0.1 to 1 &mgr;m and an average particle size in the range from 1 to 60 &mgr;m and, then, applying thereonto a second metallic paint (C) containing small thin metal flakes (b) having thicknesses not greater than 0.08 &mgr;m and an average particle size in the range from 5 to 40 &mgr;m and a clear coating (D) successively.
(5) The method as defined in the above (4), wherein the primer (A) and/or the first metallic paint (B), the second metallic paint (C) and the clear coating (D) are applied sequentially on the substrate by a wet-on-wet technique.
(6) The method as defined in the above (4), wherein a heating step is incorporated after the application of the primer (A) and/or the first metallic paint (B), whereupon the second metallic paint (C) and the clear coating (D) are applied sequentially thereonto.
(7) The method as defined in the above (4), wherein a heating step is incorporated after the primer (A) and/or the first metallic paint (B) and, then, the second metallic paint (C) have sequentially been applied, whereupon the clear coating (D) is applied thereonto.
(8) The method as defined in the above (4), wherein a heating step is incorporated after the application of the primer (A) and/or the first metallic paint (B), followed by application of the second metallic paint (C) thereonto with subsequent heating of the coating, whereupon the clear coating (D) is applied thereonto.
(9) The method for forming a coating film on a substrate by spray-coating a coating composition containing a solvent, the small thin metal flakes (b) and a film-forming resin component on the substrate using an air spray gun as defined in any one of the above (1) to (8), wherein the small thin metal flakes (b) have thicknesses not greater than 0.08 &mgr;m and an average particle size in the range from 5 to 40 &mgr;m and the film-forming resin component comprises a cellulosic resin or a cellulosic resin and resin(s) other than a cellulosic resin, the weight ratio of the small thin metal flakes (b) to the film-forming resin component being in the range from 1/0.3 to 1/40 and the content of the cellulosic resin in the film-forming resin component being in the range from 5 to 100% by weight, wherein the content of solids in the coating composition upon application is in the range from 0.1 to 10% by weight and the air spray gun has a nozzle diameter not greater than 3 mm, with the spray air pressure at the air cap being in the range from 45 to 245 kPa.
(10) The method for forming a coating film on a substrate by spray-coating a coating composition comprising a solvent, the small thin metal flakes (b) and a film-forming resin component on the substrate using a low-pressure air spray gun as defined in any one of the a
Mitsumune Shinji
Tsunoda Takeshi
BASF NOF Coatings Co., Ltd.
Flynn ,Thiel, Boutell & Tanis, P.C.
Parker Fred J.
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