Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
1999-02-22
2003-02-11
Koslow, C. Melissa (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S415000, C106S417000, C106S425000, C106S431000, C106S436000, C428S404000
Reexamination Certificate
active
06517627
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a pigment powder. More particularly, the present invention relates to a pigment powder having thereon a multilayered film which is usable as a retroreflective pigment, a weather resistant pigment, or the like for use as a raw material for a magnetic color toner, a magnetic color inks, or the like.
BACKGROUND ART
The conventional pigments for use in printing inks or copying colorants and the conventional dyes for use in dyeing each is a subtractive colorant and assumes a dark color upon color mixing. No additive pigment has been proposed so far. An additive pigment is a pigment which functions as a false light source upon irradiation with light and gives white light upon color mixing.
In the additive process, the three primary colors of R (red), G (green), and B (blue) are used as bases, and colors are produced by using various mixing ratios among these.
It is known that mixing these three primary colors gives white light.
The television tube, which is a representative of additive-process apparatuses, performs color displays based on the same color mixing.
However, additive pigments capable of developing colors based on such combinations of the three primary colors have not been realized.
Ideal white light has a spectral distribution in which the intensity has the same height throughout the wavelength range of 380 nm to 780 nm, namely, it has a distribution of, so to speak, a box shape. Natural light is considerably close to white light having a box-shape distribution.
On the other hand, ideal red light is a light having a box-shape spectral distribution in the wavelength range of 580 nm to 680 nm; ideal green light is a light having a box-shape spectral distribution in the wavelength range of 480 nm to 580 nm; and ideal violet light is a light having a box-shape spectral distribution in the wavelength range of 380 nm to 480 nm. However, virtually no pigment or dye having any of the above-described box-shape distributions has been obtained so far. Consequently, the artificial lights which have passed through filters comprising conventional colorants have bell-shape spectral distributions, in which bottom parts of the spectral curves for the three primary colors overlap with each other and which have peaks. This applies to spectra of the three primary colors in prints, photographic positives, and photographic negatives (see FIG.
4
).
Superposing red light on green light gives yellow; superposing green light on violet light gives cyan light; and superposing violet light on red light gives magenta light.
The present inventors previously investigated a method for forming a dense continuous metal oxide film on the surface of a powder by dispersing the powder into a solution of a metal alkoxide and hydrolyzing the metal alkoxide in the presence of the powder. Using this technique, the present inventors developed the following and other methods: a method for forming a multilayered metal oxide coating film on the surface of a powder made of a metal or metal oxide; a method for obtaining a powder coated with a multilayered metal oxide film, for example, by forming a silica film having a thickness of 0.01 to 0.2 &mgr;m on the surface of a powder made of a metal or metal oxide and further forming thereon a titania film having a thickness of 0.01 to 0.2 &mgr;m (JP-A-6-238604); and a method for obtaining a powder coated with a metal film and a metal oxide film by depositing a metal film alternately with a metal oxide film on the surface of a powder, specifically, for example, by forming a coating film of silver metal having a thickness of 0.01 to 0.02 &mgr;m on the surface of a powder and forming thereon a titania film having a thickness of 0.04 to 0.6 &mgr;m (JP-A-7-90310).
In forming either metal oxide films or at least one metal film and at least one metal oxide film on a powder by any of the techniques described in the aforementioned patent gazettes, a powder having a peak at a specific wavelength, i.e., at the wavelength determined by the product of the refractive index of a high-refractive-index coating film and the thickness thereof, could be obtained by forming neighboring films differing from each other in refractive index, for example, by superposing a high-refractive-index film alternately with a low-refractive-index film.
In the case of the method described above, it is thought that when the difference in refractive index between the high-refractive-index film and the low-refractive-index film is very large, then a pigment having a high reflectance is obtained by depositing the low-refractive-index film on the high-refractive-index film. A pigment having properties close to those of additive pigments is expected to be produced by further heightening the reflectance. Virtually, however, the pigment thus obtained had a spectral distribution which was not of a box shape.
Especially in the case of a black base powder, it is difficult to obtain a reflected light having a box-shape spectral distribution by the coating method in which a high-refractive-index coating film and a low-refractive-index coating film are deposited alternately, although a monochromatic reflected light having a reflection waveform with a narrow peak is obtainable.
For transparent bases, a technique of retroreflectively coloring a powder has been used in which a light of specific wavelengths is caused to pass through and a light having wavelengths outside that transmission wavelength range is reflected. However, in this case also, a box-shape spectral distribution is difficult to obtain because heightening the reflectance of the powder is not easy.
Accordingly, an object of the present invention is to provide an additive pigment having a box-shape spectral distribution. Another object of the present invention is to provide additive pigments which respectively have a high reflectance in regions corresponding to the three primary colors of light and each has a box-shape spectral distribution.
These objects of the present invention are accomplished with the following pigment powders of the present invention.
(1) An additive pigment powder comprising three pigments respectively having the three primary colors of light (red, green, and blue), wherein when the pigment powders of the three colors are mixed together, each pigment powder is subjected to additive color mixing.
(2) The additive pigment powder according to the above (1), wherein the pigment particles having the three primary color of light reflect a visible light only in a wavelength range corresponding to the color selectively and intensively, and a desired bright intermediate color can be developed by mixing these pigment particles having the three primary colors in an appropriate proportion.
(3) An additive pigment powder having blue color among the three primary colors of light, which has a peak having a light reflectance of 80% or higher in a spectral wavelength range of 380 nm to 500 nm, and has a reflection range having a light reflectance of 80% or higher in 30 to 50 nm at the both sides of the peak wavelength.
(4) An additive pigment powder having green color among the three primary colors of light, which has a peak having a light reflectance of 80% or higher in a spectral wavelength range of 500 nm to 575 nm, and has a reflection range having a light reflectance of 80% or higher in 30 to 50 nm at the both sides of the peak wavelength.
(5) An additive pigment powder having red color among the three primary colors of light, which has a peak having a light reflectance of 80% or higher in the spectral wavelength range of 575 nm to 750 nm, and has a reflection range having a light reflectance of 80% or higher in 30 to 50 nm at the both sides of the peak wavelength.
(6) The additive pigment powder according to any one of the above (1) to (5), wherein the pigment powder comprises a base particle having thereon a multilayered film, and any adjacent films of the multilayered film and the base particle differ from each other in material and in refractive index to make the pigment particle have a color due t
Atarashi Takafumi
Nakatsuka Katsuto
Koslow C. Melissa
Nittetsu Mining Co., Ltd.
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