Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-11-16
2003-05-27
Shosho, Callie (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S403000, C524S555000, C524S556000, C524S571000, C524S577000, C524S588000, C524S590000
Reexamination Certificate
active
06569919
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a reversibly discoloring composition capable of reversibly changing color according to the wavelength of an external light source and a member using the composition used as external decorating parts of dial plates, bands, etc., for wrist watches, and has a feature that the object color of the member reversibly and instantly changes color according to the wavelength of an external light source.
BACKGROUND OF THE INVENTION
Heretofore, as a substance characterized in that the color of the compound undergoes reversible discoloring by light irradiation, a photochromic molecule is known. By absorbing the energy of light irradiation, the photochromic molecule changes chemical structure and as the result thereof, the color of the compound is changed. As the photochromic molecule, spiropyran, in which the object color changes from colorless to blue-purple or red-purple by an ion dissociation, thioindigo, in which the object color changes from a purple color to a red color by a trans-cis isomerization, fulgide and dihydropyrene, in which the object color changes from colorless to a pink color by an electrocyclic reaction, triphenylimidazolyl, in which the object color changes by a radical dissociation, a thionine-base photochromic molecule, in which the object color changes by oxidation reduction, etc., are known. An example of using a photochromic molecule as a coloring material, that is a light-discoloring ink, is disclosed in U.S. Pat. No. 5,028,792 (WO 94/23062). As other uses than the above-described uses, dyeing is applied to a part of a clothing ornament using a photochromic molecule as a dye and a clothing ornament causing color changing in the portion, etc., is known.
However, in the case of using such a photochromic molecule as a coloring material, there are many cases that the reversibility of the color change is imperfect and the time required for color changing is long. Also, when the change of color by the absorption of light is repeatedly carried out, a photo-deterioration such as vanishing of reversibility of color change, etc., occurs, and further, by heat or the ultraviolet irradiation of a long time, the reversibility of color change is frequently vanished, and the photochromic molecule is not suitable for the storage for a long period of time. As described above, when the photochromic molecule of prior art is used as an external decorating part for watch, it sometimes difficult to ensure the satisfactory quality. Also, because the color change depends upon the chemical structure, the color can be changed only between colorless and one color or between two colors.
The present invention has been made in view of such circumstances and the problems of the invention are to supply easily and at a low cost an external decorating part for a watch using a member that the object color is instantly and reversibly changes according to the kind of a light source and further to ensure the quality such as the light resistance, the heat resistance, etc.
DISCLOSURE OF THE INVENTION
The reversibly discoloring composition of the invention for solving the problems is composed of fine particles made of one or more kinds of rare earth oxides represented by a formula M
2
O
3
(wherein M represents Ho, Nd, or Pr) and a light-transmitting base material having dispersed therein the fine particles.
In this case, in the rare earth oxide fine particles in the invention, the mean particle size is from about a few &mgr;m to 100 &mgr;m but it is preferred to use super fine particles having the means particle size of from 5 nm to 100 nm. When such super fine particles are used, the characteristics that the change of the color tone is large and dispersibility is good are shown and even by using the same rare earth oxide, a reversibly discoloring layer having a different color tone can be formed. In addition, the fine particles having different mean particle size may be mixed, whereby the variation of expressible colors can be increased. In addition, the fine particles having different mean particle size may be mixed, whereby the variation of expressible colors can be increased.
The light-transmitting base material in the invention includes, for example, inks or coating materials selected from an epoxymelamine-base high molecular material, a vinyl-base high molecular material, an acrylic high molecular material, a urethane-base high molecular material, a polyamide-base high molecular material, an alkid-base high molecular material, a photo-setting type high molecular material, and a high molecular material having a light transmittance. In this case, the material having a light transmittance means that the visible light transmittance of the material is at least 90%.
Also, the light-transmitting base material of the invention includes, for example, a molding material selected from an acrylic high molecular material, a polycarbonate high molecular material, an ABS high molecular material, a polyarylate high molecular material, a urethane-base high molecular material, a styrene-base high molecular material, a silicone-base high molecular material, and a high molecular material having a light transmittance. In this case, the material having a light transmittance means that the visible light transmittance of the material is at least 90%.
In the present invention, to 100 parts by weight of the light-transmitting base material, from 1 to 30 parts by weight of the rare earth oxide fine particles can be used but particularly, when the light-transmitting base material is a base material for ink, to 100 parts by weight of the base material, the rare earth oxide fine particles can be used in the range of from 1 to 50 parts by weight.
Also, to improve the dispersibility, if necessary, additives such as a wetting agent, etc., may be added.
The reversibly discoloring composition of the invention can be used for various kinds of uses but particularly, is suitably used as external decorating parts for watches, such as a dial plate, a frame, a band, a bezel, a button, etc., for watches. That is, the external decorating part for watch of the invention has the color changing portion composed of a light-transmitting base material having dispersed therein fine particles of one or more kinds of rare earth oxides represented by the formula M
2
O
3
(wherein M represents Ho, Nd, or Pr).
In this case, the rare earth oxide fine particles and the light-transmitting base material are as described above, but according to the kind of the light-transmitting base material, the forming method of the color changing portion differs.
For example, the color changing portion is formed by printing or coating a transparent ink or a transparent coating material containing the rare earth oxide fine particles or formed by molding a transparent molding material containing the rare earth oxide fine particles. Practically, a high molecular material layer containing the rare earth oxide fine particles is formed in an optional form by printing b such as screen printing, etc., or coating on a dial plate, etc., which is an external decorating part for a watch. Also, it is possible that after dispersing a proper amount of the rare above-described earth oxide fine particles in a transparent resin such as a polycarbonate resin, a urethane resin, etc., pellets are formed from the dispersion, and thereafter, by applying a molding work such as injection molding, etc., the pellets are molded to a desired form, which is used as an external decorating part for a watch or a member of the external decorating part for a watch.
The color changing portion thus formed changes the color thereof reversibly and instantly according to the kind of an external light source such as sunlight, an ordinary type fluorescent lamp, a three-wavelength region light-emitting type fluorescent lamp, etc.
Such a color changing portion may be used as a part of the member or may be used as the whole portion. Also, the color changing portion may be covered with the transparent layer or member made of a light-transmitting material. In this
Ikeda Yasuhisa
Morita Kiichiro
Noguchi Koichi
Tanaka Takayoshi
Adams & Wilks
Seiko Instruments Inc.
Shosho Callie
LandOfFree
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