Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2001-04-13
2004-05-04
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031280, C106S031600
Reexamination Certificate
active
06730154
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polychromic ink composition depending on viewing angle which can be suitably used for writing instruments, stamps, paints, cosmetics, or the like.
2. Description of the Prior Art
Heretofore, for the purpose of obtaining written marks with metallic color such as gold, silver, or the like, and with pearlescent luster, ink compositions using metallic pigments or pearlescent pigments have been proposed. For example, Japanese Unexamined Patent Publication No. 7-118592 proposes an aqueous ink composition using aluminum pigments. Further, Japanese Unexamined Patent Publication No. 8-151547 proposes an aqueous ink composition using pearlescent pigments.
However, in the case of such conventional aqueous ink compositions using metallic pigments, it has been impossible to obtain written marks or coating films with an effect that different colors are to be perceived depending on viewing angle (polychroism depending on viewing angle: goniochromism). Although ink compositions using pearlescent pigments have pearlescent luster, polychroism depending on viewing angle is hardly perceived. In particular, no polychroism depending on viewing angle can be perceived when a substrate whose color reflects light, including a white-colored substrate. On the other hand, in order to prepare ink compositions preferably used for writing instruments or the like including ball-point pens, it is important to prepare inks with good dispersal stability, capable of preventing the sedimentation of the pigment particles and excellent in maintenance stability whether they are oily types or aqueous types.
SUMMARY OF THE INVENTION
The present invention relates to a polychromic ink composition depending on viewing angle comprising polychromic particles depending on viewing angle, in particular, polychromic particles depending on viewing angle having optical reflection layers, solvents, and shear-thinning property imparting agents. Here, the polychromic particles depending on viewing angle in the present invention are defined as the particles which show such an effect that different colors are to be perceived depending on viewing angle (polychroism depending on viewing angle: goniochromism). When the ink composition of the present invention comprising these particles, solvents, and shear-thinning property imparting agents is written or coated, the written marks or coating films contain polychromic particles depending on viewing angle. Consequently, when incident light comes into these particles which are contained in the written marks or coating films, light coming out from inside of the particles to outside of the particles strongly interferes and interference color is observed in which different colors are to be perceived depending on viewing angle, thereby obtaining written marks or coating films with polychroism depending on viewing angle that have not been attained in the past.
In particular, as a mode of preferred embodiment, in the ink composition wherein the polychromic particles depending on viewing angle having optical reflection layers are contained, these optical reflection layers function as an opacifying agent of the said particles by themselves, and the polychroism depending on viewing angle can be observed regardless of the color of the substrate including colorants or the like which are written or coated at the same time as an ink. In other words, in the case of these particles, regardless of the color of the substrate, the interference color can be observed in which different colors are perceived depending on viewing angle due to the light coming out from inside of the particles to the outside of the particles, thereby obtaining the written marks or coating films that have not been attained by using the conventional metallic pigments or pearlescent pigments. In particular, even in the case of a white-colored substrate which reflects light, as a result of specular reflection of the incident light or as a result that light is reflected partially, written marks or coating films with polychroism depending on viewing angle can be obtained. Here, “polychromic particles depending on viewing angle having optical reflection layers” refer to the polychromic particles depending on viewing angle having one or more optical reflection layers that can reflect specularly or that can reflect light partially when the light comes into, is refracted, and transmitted. Preferably, the “polychromic particles depending on viewing angle having optical reflection layers” refer to the polychromic particles depending on viewing angle having such optical reflection layers whose reflectance is greater than transmittance of the incident light.
In addition, since the ink composition of the present invention is the ink composition which comprises solvents and shear-thinning property imparting agents as well as polychromic particles depending on viewing angle, such an ink is prepared whose dispersal stability of the said polychromic particles depending on viewing angle is good, capable of preventing the sedimentation of the said particles, excellent in maintenance stability. As a particularly preferred mode of embodiment, in the case of an ink composition comprising polychromic particles depending on viewing angle consisting of multi-layered particles including several metallic components, although the specific gravity is larger compared with that of ordinary pigments and that of pigment particles comprising the simple substance metals including aluminum or the like, when such an ink composition comprising polychromic particles depending on viewing angle contains a shear-thinning property imparting agent, the sedimentation of the said particles can be prevented, thereby obtaining an ink excellent in maintenance stability. Further, as a particularly preferred mode of embodiment, in the case of an ink composition comprising polychromic particles depending on viewing angle comprising the said cholesteric liquid crystal polymer, although the particle diameter is larger compared with that of pigments which are used for felt-tip pens and ball-point pens, when such an ink composition comprising polychromic particles depending on viewing angle contains shear-thinning property imparting agents, the sedimentation of the said particles can be prevented, and the maintenance stability becomes good, thereby obtaining an ink excellent in practical use which is applied for writing instruments including ball-point pens or the like.
The object of the present invention is to provide a polychromic ink composition depending on viewing angle which can obtain written marks or coating films having polychroism depending on viewing angle which have not been realized by using the conventional metallic pigments or pearlescent pigments.
Another object of the present invention is to provide a polychromic ink composition depending on viewing angle which can obtain written marks or coating films having polychroism depending on viewing angle particularly on a white-colored substrate.
The other object of the present invention is to provide a polychromic ink composition depending on viewing angle capable of attaining each of the above described objects with good dispersal stability, capable of preventing the sedimentation of the pigment particles, and showing the excellent maintenance stability.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Polychromic Particles Depending on Viewing Angle
As described above, polychromic particles depending on viewing angle of the present invention (polychromic pigments depending on viewing angle/dichroic pigments) are defined as a generic term of pigment particles in which the color tone (interference color) changes depending on viewing angle. The examples include multi-layered pigments such as minerals, metals, metallic compounds, and metal oxides, liquid crystal polymers, and multi-layered body of liquid crystal polymers or the like. These polychromic multi-layered particles depending on viewing angle show the polychromic effect depending on viewing a
Fukuo Hidetoshi
Hirano Norihiro
Inoue Hiroshi
Maruyama Satoshi
Matsumoto Kaoru
Faison Veronica F.
Merchant & Gould P.C.
Sakura Color Products Corporation
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