Aqueous dispersion of globular silicone elastomer particles

Details Aqueous dispersion of globular silicone elastomer particles Aqueous dispersion of globular silicone elastomer particles

2001-06-14

2003-07-08

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Particulate form

C424S490000, C424S401000, C424S497000, C424S496000

Reexamination Certificate

active

06589561

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a novel aqueous dispersion of globular silicone elastomer particles or, more particularly, the invention relates to an aqueous dispersion of globular particles of a composite silicone elastomer, of which each particle has a composite structure consisting of a crosslinked organopolysiloxane as the matrix phase and pigment particles as the dispersed phase in the matrix phase, having usefulness as an adjuvant in toiletry or cosmetic preparations.
A dry powder or an aqueous dispersion of globular silicone elastomer particles is a well known material in the prior art. For example, several methods are proposed for the preparation of such a product including a method in which an organopolysiloxane having silicon-bonded vinyl groups and an organohydrogenpolysiloxane having silicon-bonded hydrogen atoms are co-emulsified in an aqueous medium containing a surfactant to give an aqueous emulsion which is then admixed with a catalytic amount of a platinum compound as a catalyst for the hydrosilation reaction between the silicon-bonded vinyl groups and silicon-bonded hydrogen atoms to effect crosslinking (see Japanese Patent Kokai 56-36546, 62-257939 and 3-93834), a method in which a curable organopolysiloxane composition is sprayed and heated in a hot air atmosphere to effect curing (see Japanese Patent Kokai 59-68333), a method in which a mixture consisting of an organopolysiloxane having silicon-bonded alkenyl groups, an organohydrogenpolysiloxane and a catalytic platinum compound is emulsified in water at 0 to 25° C. and the aqueous emulsion is added to and dispersed in water at 25° C. or higher (see Japanese Patent Kokai 62-243621 and 63-77942), a method in which a mixture consisting of an organopolysiloxane having olefinically unsaturated groups bonded to the silicon atoms and an organohydrogenpolysiloxane having mercaptoalkyl groups is emulsified in an aqueous medium and irradiated with ultraviolet light to effect curing of the droplets (see Japanese Patent Kokai 60-106837), a method in which a mixture of an amino group-containing organopolysiloxane and a second organopolysiloxane having acrylic-functional groups is emulsified in an aqueous medium to effect in situ curing (see Japanese Patent Kokai 63-128075), a method in which a mixture consisting of an organopolysiloxane having silanol groups, an organohydrogenpolysiloxane and a curing catalyst is dispersed in an aqueous medium and then brought into contact with a liquid or gas at a high temperature to effect curing (see Japanese Patent Kokai 63-202658), a method in which an organopolysiloxane having acryloxy, methacryloxy or acrylamido groups is dispersed in a liquid medium and irradiated with ultraviolet light to effect curing (see Japanese Patent Kokai 63-258639), a method in which a mixture of organosilicon compounds selected from organosilane compounds and organopolysiloxanes is subjected to a condensation reaction to effect curing in a solvent mainly consisting of a nitrogen-containing aromatic compound in the presence of a—condensation catalyst (see Japanese Patent Kokai 63-312324), a method in which a mixture of organosilicon compounds selected from organosilane compounds and organopolysiloxanes is subjected to a condensation reaction to effect curing in a solvent mainly consisting of an amine, amide or nitrile compound in the presence of a condensation catalyst (see Japanese Patent Kokai 63-312325), a method in which a mixture of a vinyl group-containing organopolysiloxane, organohydrogenpolysiloxane and catalytic platinum compound is emulsified followed by curing (see Japanese Patent Kokai 1-306471), a method in which an organopolysiloxane having silicon-bonded aliphatically unsaturated groups and mercapto groups is emulsified to give an aqueous emulsion which is irradiated with ultraviolet light in the presence of a photosensitizer to effect curing (see Japanese Patent Kokai 3-95268), a method in which a vinyl group-containing organohydrogenpolysiloxane in the form of an aqueous emulsion is subjected to curing in a gas or in a non-miscible liquid at 25° C. or higher (see Japanese Patent Kokai 4-72358), a method in which a mixture consisting of a vinyl group-containing organopolysiloxane, organohydrogenpolysiloxane and catalytic platinum compound is sprayed through a nozzle into water and emulsified therein followed by curing (see Japanese Patent Kokai 61-223032, 1-178523 and 2-6109) and so on.
Further, Japanese Patent Kokai 10-139624 discloses a cosmetic preparation with water as the dispersion medium by the addition and compounding of an aqueous dispersion of a silicone rubber powder. While these silicon elastomer particles prepared by the above described methods may exhibit an improvement in the lubricity when compounded in a cosmetic preparation, a disadvantage is caused thereby due to a decrease in the ultraviolet-shielding effect of the cosmetic preparations. In addition, a cosmetic preparation of which water is the dispersion medium of effective ingredients suffers a problem when compounded with globular silicone elastomer particles that the silicone elastomer particles are separated from the base of the cosmetic preparation because the silicone elastomer particles have a true density smaller than that of the dispersion medium.
On the other hand, proposals are made for silicone elastomer particles compounded with a non-silicone material. For example, Japanese Patent Kokai 63-251464 discloses silicone elastomer particles containing an electroconductive material such as carbon blacks. Although good ultraviolet-shielding effect can be obtained with such carbon black-containing silicone elastomer particles, these particles can hardly be employed as an adjuvant in a cosmetic or toiletry preparation because the particles are naturally colored in black so deeply. Japanese Patent Kokai 64-56735 discloses silicone elastomer particles compounded with an epoxy compound having an unsaturated hydrocarbon group in the molecule. Japanese Patent Kokai 64-70558 discloses silicone elastomer particles compounded with an alkoxysilane compound having an epoxy, alkenyl or amino group in the molecule. Japanese Patent Kokai 1-81856 discloses silicone elastomer particles compounded with a silicone oil. Japanese Patent Kokai 2-218710 discloses silicone elastomer particles compounded with particles of a thermoplastic resin. Japanese Patent Kokai 2-232263 discloses silicone elastomer particles compounded with fumed silica particles or precipitated silica particles. Japanese Patent Kokai 4-168117 discloses silicone elastomer particles compounded with precipitated silica particles after a surface treatment with an organopolysiloxane. Japanese Patent Kokai 3-281536 and 10-36675 disclose silicone elastomer particles compounded with colloidal silica particles. Japanese Patent Kokai 11-1615 discloses silicone elastomer particles compounded with a cationic surfactant.
The above described products of silicone elastomer-based particles compounded with a variety of additive ingredients, however, cannot be imparted with an ultraviolet-shielding effect substantially higher than in silicone elastomer particles uncompounded with such an additive ingredient. Moreover, silicone elastomer particles compounded with silica particles before a surface treatment suffer a decrease in the surface lubricity. Further, Japanese Patent Kokai 3-294357 proposes a method for the preparation of silicone elastomer particles containing additive particles in which an organopolysiloxane composition curable into a silicone elastomer is blended before curing with the additive particles to be carried by the additive particles followed by curing of the organopolysiloxane into an elastomer. This method, however, involves difficult problems that the particles can hardly be imparted with good globularity or sphericity of the particle configuration and the particle diameter of the particles can be controlled only with a great difficulty.
It is widely practiced in the prior art that a cosmetic preparation is compounded with f

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