Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
2002-09-18
2004-08-31
Koslow, C. Melissa (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S404000, C106S415000, C106S418000, C106S419000, C106S425000, C106S435000, C106S436000, C106S438000, C106S439000, C106S447000, C106S454000
Reexamination Certificate
active
06783584
ABSTRACT:
BACKGROUND OF THE INVENTION
Decorative pigments are used in various fields of cosmetics, plastics, paints, etc. Their typical examples are pearlescent pigments, metallic pigments, thin metal film-deposited film chips, etc.
Pearlescent pigments are widely used as coloring matters of pearly gloss, but when compared with metallic pigments, they are problematic in point of their luster (brilliance) and their hiding power (hiding ability of back ground) ability.
Metallic pigments are widely used, for example, typically for paints. In particular, aluminum flakes are one typical example of silver metallic pigments and are highly brilliant. They are inexpensive, and are stably supplied on the market. Recent attempts in the art of pigments with hiding power such as aluminum flakes, are to attain new colors. Metallic pigments have a strong metallic luster and their hiding power is good. But, when compared with pearlescent pigments, their appearance is often poor as their reflection light is too strong. In particular, conventional metallic pigments coated with metal oxides having high refractive index or the like to provide an interference color are problematic in that their color is weak.
Film chips having a vapor-deposited thin film of metal, have a metallic luster, are lightweight, and are easy to handle. However, they require a step of cutting the films in their production. For example, an optically variable pigment(a pigment having different hue when viewed from different angles) is prepared by deposition of aluminum or the like, a dielectric layer and further a metal film as semi-transparent reflecting layer, and this has a flop effect appearance and high chromaticity. However, since this is prepared by depositing a thin metal layer with sputtering equipment, it cannot be directly coated into fine particles like ordinary pigments. In practice, this requires a step of cutting the metal film-deposited sheet into pigment chips. Therefore, the edges of the thus-cut pigment chips are not coated with the metal film, and their waterproofness and heat resistance are not good. This is especially problematic when the substrate is a metallic pigment. In addition, the sputtering equipment is generally large and expensive. Apart from the above, also disclosed is a technique of coating the surface of aluminum flakes or the like with a multi-layered film through chemical vapor deposition methods. However, this is still not sufficient for forming a uniform submicron-order film on flaky substrates. In addition, this requires large-scale expensive equipment like the sputtering equipment as above (See Japanese Patent Laid-Open No. 258579/1995).
SUMMARY OF THE INVENTION
The subject matter of the invention includes solving the problems discussed above, and providing a high-chromatic flaky pigment having enhanced interference colors and di-chromatic effect, and also providing a method for producing the flaky pigment in a simple and inexpensive apparatus.
On this basis, the present inventors have discovered a flaky pigment having high-chromatic interference color. Particularly, it was found that coating a metal oxide-coated flaky pigment further with a semi-transparent thin metal film, provides a pigment with a strong interference color and flop effect.
In one embodiment the invention includes a high-chromatic flaky pigment, the entire surface of the flaky substrate being coated with a metal oxide providing an interference color and further coated with a semi-transparent thin metal film to enhance the interference color of the pigment.
The invention also relates to the high-chromatic flaky pigment in which the flaky substrate is preferably a metal pigment.
The invention further relates to the high-chromatic flaky pigment in which the metal oxide having an interference color is preferably one or more metal oxides selected from the group consisting of titanium dioxide, zirconium oxide, iron oxide, zinc oxide, tin oxide and cerium oxide.
The invention further relates to the high-chromatic flaky pigment in which the semi-transparent thin metal film preferably has a thickness of at most 0.05 &mgr;m.
The invention further relates to the high-chromatic flaky pigment in which the semi-transparent thin metal film is preferably formed of one or more metals selected from a group consisting of Ni, Zn, Cr, Co, Cu, Pt, Ag, Au, and their alloys.
The invention further relates to the high-chromatic flaky pigment in which the semi-transparent thin metal film is preferably a dense film of metal particles aligned continuously therein.
The invention further relates to the high-chromatic flaky pigment in which the semi-transparent thin metal film is preferably formed through reduction of an acetylacetonato-metal complex in an organic solvent.
The invention further relates to the high-chromatic flaky pigment in which the flaky substrate is preferably a metal pigment coated with a silicon dioxide film or an aluminum oxide as a protective film.
The invention further relates to the high-chromatic flaky pigment in which the flaky substrate preferably is of aluminum flakes.
The invention further relates to a method for producing a high-chromatic flaky pigment, which comprises coating the entire surface of a flaky substrate with a metal oxide, further coating the entire surface of the metal oxide-coated flaky pigment with a metal layer through reduction of an acetylacetonato-metal complex in an organic solvent, and drying it to form a semi-transparent thin metal film thereon.
The invention further relates to the use of the flaky pigment for paints, inks, security inks, powder coatings, plastics, resin moldings, cosmetics, for the preparation of granules, or for preventing forgeries by use in a security document.
The high-chromatic flaky pigment of the invention is preferably coated with a metal oxide which has high refractive index. Therefore, the metal oxide-coated flaky pigment has an interference color of itself, and its color reproducibility is good in its production.
According to the invention, a flaky pigment coated with a metal oxide having an interference color is further coated with a semi-transparent thin metal film, and, surprisingly, its interference color is thereby enhanced directly as it is, and, in addition, the thus-coated flaky pigment has di-chromatic effect.
Moreover, since the flaky pigment of the invention is characterized in that the entire surface of its substrate is coated with a thin metal oxide film and further with a semi-transparent thin metal film, it has excellent waterproofness, durability and heat resistance. The semi-transparent thin metal film is also provided over the entire surface of the metal oxide film.
Further, according to the invention, a uniform and dense thin film of metal particles can be formed to cover the surface of a flaky pigment in an extremely simple and inexpensive method not requiring an expensive large-scale apparatus such as a sputtering unit.
The invention is described in more detail hereinunder, but is not limited to the following description.
Flaky Substrate
The flaky substrate, that is, the pigment substrate for use in the invention may be a metal pigment in flake form, including, for example, aluminum, stainless steel, titanium, copper, brass, tin, iron, bronze, cuprite, etc. For example, aluminum flakes are preferred, as they are commercially stably supplied and are inexpensive. Preferably, the pigment particles have a average size falling between 5 and 100 &mgr;m, more preferably between 5 and 50 &mgr;m. Such pigment particles not larger than 100 &mgr;m in size are preferred, as they well disperse in coating compositions, not sedimenting therein, and are easy to handle. They may have a thickness falling between 0.1 and 5 &mgr;m.
Protective Film
Of the flaky substrates, it is desirable that the metal pigment is previously coated with a protective film. With the coating, the stability and the weather resistance of the metal pigment itself are improved, and, in addition, the adhesiveness between the metal pigment and a metal oxide layer to be formed to cover it is improve
Koslow C. Melissa
Manlove Shalie
Merck Patent GmbH
Millen White Zelano & Branigan P.C.
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