Coating processes – Solid particles or fibers applied – Uniting particles to form continuous coating with...
Reexamination Certificate
1998-08-26
2001-03-27
Cameron, Erma (Department: 1762)
Coating processes
Solid particles or fibers applied
Uniting particles to form continuous coating with...
C427S203000, C427S205000, C427S404000, C427S407100, C427S409000, C106S404000
Reexamination Certificate
active
06207226
ABSTRACT:
This invention relates to a novel metallic coating method.
A metallic coating finishing method by “2 coat-1 bake” system is known, which comprises applying a metallic paint containing a paint resin composition and aluminum flakes onto a substrate, further applying onto the uncured metallic paint-coated surface a clear paint which forms a transparent coating film, and then curing this two-layered coating film simultaneously by heating, and the technique has been widely used for top coating of automobile body panels and the like. The metallic coating film exhibits glittering brilliancy and excels in designability.
It is ideal for aluminum flakes in this metallic coating film to be oriented in parallel with the coated surface. In reality, however, they often are oriented irregularly and it is difficult to form a metallic coating film retaining the excellent white, metallic luster inherent in aluminum flakes and moreover having strong flip-flop properties.
I have engaged in extensive studies in search for a method for forming a metallic coating film in which aluminum flakes are oriented in parallel with the coated surface, which excels in whiteness and metallic luster (glittering effect) and moreover has strong flip-flop properties. In consequence, I now discovered: by formulating a dispersion of aluminum flakes, which have been treated (coated) with a specific phosphoric acid alkyl ester, in an organic solvent and applying the same to the surface coated with uncured paint film, aluminum flakes are oriented in parallel with the coated surface to accomplish the intended effect. The present invention is thus completed.
According to the present invention, therefore, a metallic coating method is provided, which method is characterized by applying a dispersion formed by dispersing aluminum flakes which have been surface-treated with a C
8
-C
18
alkyl ester of phosphoric acid in an organic solvent, onto uncured coated surface of a paint-coated object, then applying onto the dispersion-applied surface a clear paint and thereafter applying heat to simultaneously cure these coating films.
The method of this invention is capable of forming a metallic coating film which is white and excellent in metallic luster (glittering effect) and moreover has strong flip-flop properties. Here “strong flip-flop properties” means: when the aluminum flake-containing metallic coating film is observed, from the frontal direction (at a right angle to the coated surface) it appears white and glitters to produce excellent brilliancy. Whereas, from diagonal directions the brilliancy is less and the coated surface appears dark, largely differing from the former case. That is, a metallic coating film whose metallic effect markedly varies depending on the angle of observation is said to have “strong flip-flop properties”. Such a coating film is rich in designability.
In the method of the present invention, “uncured, coated surface” of the coating object onto which a paint has been applied corresponds to the surface of the coating object to be applied with a dispersion of aluminum flakes in organic solvent, said aluminum flakes having been surface-treated with a C
8
-C
18
alkyl ester of phosphoric acid. While this surface may be formed by applying an air drying type base paint, it is generally preferred to form it by applying a thermosetting base paint (A) which comprises, for example, a base resin, crosslinking agent and organic solvent.
Examples of the base resin to be used in said base paint (A) include resins having crosslinkable functional groups like hydroxyl groups, eg., polyester resin, alkyd resin, acrylic resin and vinyl resin. As the crosslinking agent, compounds or resins crosslinkable with the functional groups, such as melamine resin and optionally blocked polyisocyanate compound can be used. As the organic solvent, any of customarily used solvents for paints such as hydrocarbon type, ester type, ether type, alcohol type and ketone type solvents can be used. Generally suitable blend ratios of such base resin to crosslinking agent in the base paint (A) are such that, based on the total weight of solid contents of the two components, the base resin is within a range of 50-90%, in particular, 60-85%, and the cross-linking agent, 50-10%, in particular, 40-15%.
Besides said base resin, crosslinking agent and organic solvent, if necessary other additives such as coloring pigment, brilliant pigment, extender, curing catalyst, face regulator, anti-oxidant, flowability-regulating agent, pigment disperser and the like may be suitably blended into the base paint (A).
According to the method of the present invention, the base paint (A) is directly applicable to metallic or plastic coating objects such as automobile body panels, or onto a substrate which has been applied with an undercoat such as an electropaint and optionally with a surfacer, and cured.
Said base paint (A) is preferably applied to such surfaces of coating objects by such means as electrostatic coating, airless spray, air spray or the like, to a thickness, in terms of cured coating film thickness, of from about 1 to about 45 &mgr;m, in particular, from about 10 to about 30 &mgr;m.
Said “uncured coated surface” onto which a dispersion (B) of aluminum flakes in organic solvent is to be applied, said aluminum flakes having been surface-treated with a C
8
-C
18
alkyl ester of phosphoric acid in accordance with the present invention, may be one which has been applied with uncured coating of above-described base paint (A). More specifically a surface coated with the base paint (A) and subsequently allowed to stand for several minutes or more at room temperature is preferred. Whereas, when the coated surface is further subjected to a compulsory drying at 50-100° C. for 1-30 minutes after the air drying, the resulting coated surface (preferably having a gel ratio not higher than 60% by weight, in particular, not higher than 40% by weight) also is included in the “uncured coated surface” according to the present invention. Here the “gel ratio” is determined as follows: a coating film after the compulsory drying is extracted with acetone at reflux temperature for 5 hours, and the residual ratio of the coating film after the extraction versus before the extraction is expressed by % by weight.
The dispersion (B) to be applied onto the “uncured coated surface” is prepared by dispersing aluminum flakes which have been surface-treated with a C
8
-C
18
alkyl ester of phosphoric acid in an organic solvent.
Aluminum flakes to be used in said dispersion (B) can be those known per se, for example, metal aluminum which is mechanically crushed into flakes by stamp mill process, dry ball mill process, wet ball mill process or the like; and also leafing type and non-leafing type aluminum flakes whose surfaces are coated with long chain fatty acid such as stearic acid, oleic acid and the like which is used as a lubricant in the occasion of crushing. Generally preferred size of these aluminum flakes is such that their longitudinal length is within a range of 2-50 &mgr;m, in particular, 10-30 &mgr;m and thickness, within a range of 0.1-2 &mgr;m, in particular, 0.3-1 &mgr;m.
As the C
8
-C
18
alkyl esters of phosphoric acid which are used for surface treatment (coating) of the aluminum flakes, compounds expressed by a formula
(OH)m—P═O(OR)n
(in which m is 1 or 2, n is 1 or 2, m+n being 3, and
R is a C
8
-C
18
preferably C
12
-C
18
, straight chain or branched chain alkyl group)
are suitable, specific examples including dinonanoic acid phosphate, dioctanoic acid phosphate, dilaury acid phosphate, monolauril acid phosphate, ditridecyl acid phosphate, monotridecyl acid phosphate, distearyl acid phosphate, monostearyl acid phosphate, diisostearyl acid phosphate, monoisostearyl acid phosphate, dioleyl acid phosphate and monooleyl acid phosphate, which can be used either alone or in combination of two or more.
As methods for surface-treating aluminum flakes using above phosphoric acid alkyl esters, for example, the following may be used:
(1) to conduct aforesaid cr
Cameron Erma
Kansai Paint Co. Ltd.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Metallic coating method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Metallic coating method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Metallic coating method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2512047