Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Reexamination Certificate
2000-02-10
2002-05-14
Kiliman, Leszek (Department: 1773)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
C428S407000, C525S309000, C525S310000, C523S201000, C523S202000
Reexamination Certificate
active
06387497
ABSTRACT:
TECHNICAL FIELD
The present invention relates to synthetic organic particles, a process for producing the same, and the use thereof. More precisely, the present invention relates to synthetic organic particles having elasticity like rubber or ultraviolet ray absorbing function, a process for producing the same, and their application to cosmetics.
PRIOR ART
Various powders have been used as cosmetic powder materials. They include various inorganic powders, for example, natural minerals such as talc, sericite, and muscovite; and metal oxides such as titanium oxide, lead oxide, and zinc oxide.
On the other hand, finely powdered products of natural organic materials such as cellulose or silk have also been used. Recently, various materials, such as finely powdered synthetic resins, or fine particles synthesized in a special process have been frequently applied to cosmetics. The examples of such materials are nylon powder, polyacrylonitrile powder, polyester powder, polystyrene powder, polypropylene powder, polyethylene powder, tetrafluoroethylene powder, polymethylmethacrylate powder, silicone powder, and the like.
These powders synthesized from organic polymers can be more easily processed into uniform particle sizes and shapes in their synthesizing processes than inorganic powders. In addition, they possess other advantages, such as low oppression on skin owing to their low specific gravity. Hence they have been recently consumed in great quantity.
The powders of natural minerals or metal oxides are not proper as the powder material for cosmetics. Because their particle shape isn't uniform, varying into sphere, scale, needle, and amorphous shapes, and their particle size also varies from several to several dozens of microns. In addition, inorganic compounds are not compatible to skin due to their high specific gravity, and cause some troubles such as rough touch on skin.
Organic fine particles used as powder materials for cosmetics are usually made of all-purpose resins. And the powders of oval or spherical particle shape are preferred because the powders of scale or needle-like particle shape or amorphous shape obtained by mechanical pulverization give rough touch on skin. Particularly, spherical fine particles give better smoothness on skin than others owing to its rolling effect.
The development of spherical fine particles having rubbery elasticity for cosmetics has been required because most of organic fine particles don't give satisfactory soft touch to skin due to their poor elasticity. A process for producing elastic acrylic fine particles is disclosed in Japanese Patent Laid-Open Application 3-37201. The particles disclosed therein can exist in the shape of spherical particles only in a dispersion medium, and fuse to coagulate into lumps through drying process. Such coagulated particles cannot be separated into powder.
By the way, cosmetics containing an ultraviolet-ray absorber are used to screen or absorb ultraviolet ray, the ray which is contained in the sunlight and causes sunburn, liver spots, or freckles on human skin.
The ultraviolet-ray absorbers currently used include inorganic pigments, which screen ultraviolet ray, such as titanium dioxide, zinc oxide, and iron oxide; and organic ultraviolet-ray absorbers, which absorb ultraviolet ray. The above inorganic pigments cover skin for screening ultraviolet ray, and they cannot be blended a lot in cosmetics, because they whiten or color skin.
On the contrary, organic ultraviolet-ray absorbers absorb ultraviolet ray without covering skin, and do not cause such problems as whitening or coloring of skin. This is the reason why organic ultraviolet-ray absorbers have been increasingly used as the ultraviolet-ray absorbers for cosmetics in recent years.
However, many of the organic ultraviolet-ray absorbers irritate skin due to their skin-irritation property when they are directly blended with other cosmetic materials and applied to skin.
For preventing such organic ultraviolet-ray absorbers from direct contact to skin, it has been proposed to disperse and confine them in the inside of resin particles. Japanese Patent Publication 62-51931 and Japanese Patent Laid-Open Application 62-198612 disclose resin particles in which such organic ultraviolet-ray absorbers are encapsulated.
The encapsulation of organic ultraviolet-ray absorbers in resin particles was supposed to minimize the direct contact of ultraviolet-ray absorbers to skin, and to achieve lower skin irritation than that by cosmetics to which ultraviolet-ray absorbers were directly blended. Consequently, the use of resin particles in which organic ultraviolet-ray absorbers were encapsulated was expected to eliminate skin irritation. But actually skin irritation by ultraviolet-ray absorbers sometimes occurred even with such resin particles.
Because the organic ultraviolet-ray absorbers were only physically encapsulated in the pores of the resin particles, not being combined to the molecules of the resin, and were carried out of the pores by the base oils of cosmetics when such base oils penetrate into the pores. In an actual measurement, the amount of organic ultraviolet-ray absorbers, which were carried out of resin particles sometimes, reached to several percent of the whole of the absorbers encapsulated in resin particles. The ultraviolet-ray absorbers carried out of resin particles have caused skin irritation.
Japanese Patent Laid-Open Application 7-291845 discloses resin particles, which release slight ultraviolet-ray absorbers. However, even such resin particles irritate skin due to the direct contact of benzotriazole skeleton, which has ultraviolet-ray absorbing function and is combined with the molecules of the resin.
DISCLOSURE OF INVENTION
The object of the present invention is to provide synthetic organic particles having rubbery elasticity or ultraviolet-ray absorbing function.
Another object of the present invention is to provide, synthetic organic particles having sufficient rubbery elasticity and shape-retaining property.
Further object of the present invention is to provide synthetic organic particles having rubbery elasticity, which are blended in cosmetics to attain rolling effect, spreadability and dry or soft creamy touch on skin.
Further object of the present invention is to provide synthetic organic particles possessing sufficient ultraviolet-ray absorbing function and shape-retaining property.
Further object of the present invention is to provide synthetic organic particles, which are blended in cosmetics to impart sufficient ultraviolet-ray absorbing property to the cosmetics without irritating skin.
Further object of the present invention is to provide an industrially advantageous process for producing the said synthetic organic particles.
Further object of the present invention is to provide cosmetics containing the said synthetic organic particles as the application thereof.
Further objects and advantages of the present invention will be apparent from the following description.
The above objects and advantages of the present invention are achieved, first, with synthetic organic particles (hereinafter referred to as the first synthetic organic particles of the present invention) characterized by comprising:
(A) cores of an organic polymer, the organic polymer being a copolymer comprising 80 to 99 weight percent of a lower alkyl acrylate and 1 to 20 weight percent of a polyfunctional vinyl monomer, and having rubbery elasticity, and
(B) a surface layer of a methacrylate resin formed on the surface of the said cores; and having
(C) rubbery elasticity.
Second, the above objects and advantages of the present invention are achieved with synthetic organic particles (hereinafter referred to as the second synthetic organic particles of the present invention) characterized by comprising:
(A′) cores of an organic polymer, the organic polymer being a copolymer of a reactive benzotriazole compound and a (meth)acrylic monomer, and having ultraviolet-ray absorbing function, and
(B′) a surface layer of a methacrylate resin formed on
Nishida Mitsutoshi
Takahara Ichiro
Kiliman Leszek
Matsumoto Yushi-Seiyaku Co Ltd
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