An encapsulation process employs an aqueous dispersion of silica having a particle size not substantially greater than 100 nm. An emulsion is formed by high shear mixing of the silica dispersion with the material to be encapsulated and the emulsion is gelled. The process allows hydrophobic materials to be encapsulated in structures which have a high loading of the material and a good degree of imperviousness in the presence of other materials such as surfactants and mineral oils. Using the process, hydrophobic materials such as flavours, fragrances and cosmetic ingredients can be encapsulated for delayed release in a wide variety of products.
This is a continuation of application Ser. No. 07/962,907, filed on Oct. 19, 1992, which was abandoned upon the filing hereof which is a division of application Ser. No. 07/766,780, filed Sep. 27, 1991, now U.S. Pat. No. 5,185,155.
Various materials, including generally non-compatible materials may be provided from a single delivery system by a unique encapsulation system. An encapsulation system is advantageously constructed as a core of aqueous liquid having at least 5% by weight water therein, and an encapsulant surrounding the core to form a stable encapsulated particle, the encapsulant comprising at least one layer of hydrophobic particles in contact with and surrounding the core, the core and hydrophobic particles providing an encapsulated system that has an average weight average particle diameter of from 0.05 to 25 micrometers and can support its own weight. The encapsulation system may be provided by a novel method of manufacture comprising providing a mass of hydrophobic particles having average mass diameter size of between 0.05 and 25 micrometers, providing droplets of an aqueous medium to the mass of particles, gently mixing the fine particles of aqueous medium and the hydrophobic particles to form a stable encapsulant system of droplets of the aqueous medium encapsulated by a shell of particles.
The present invention generally relates to safe and stable sunscreen compositions comprising of at least one sunscreen active ingredient in the form of an inert sol-gel microcapsules encapsulating ultraviolet absorbing compounds in any acceptable cosmetic vehicle. The composition according to the present invention can comprise several ultraviolet absorbers that may be encapsulated in the same sol-gel microcapsule or in different capsules. The hydophobicity/hydrophilicity character of the sol-gel microcapsules can be controlled by selecting suitable sol-gel precursors and suitable reaction conditions and can be chosen to be compatible with the cosmetic vehicle to be used in the sunscreen composition, thus, the present invention facilitates an easy incorporation of the composite sol-gel encapsulated sunscreen in all types of cosmetic vehicles including oil free compositions, with no necessary steps of heating or high shear forces. The sunscreen compositions of the present invention can comprise any acceptable UVA and/or UVB absorbing compounds at any desired ratio to obtain a desired accumulative ultraviolet screening spectrum.
Objects of the present invention are to provide a microcapsule which can effectively and easily achieve: the prevention and adjustment of the bleeding-out of the encapsulated liquid substance from the capsule shell; and the enhancement and adjustment of the physical strength of the microcapsule; and to further provide a sheet and an electrophoretic display, both of which involve using the above microcapsules. As means of achieving these objects, the microcapsule according to the present invention is a microcapsule comprising a shell and a liquid substance that is encapsulated in the shell, with the microcapsule being characterized in that the shell contains fine particles having particle diameters of not larger than 1 .mu.m. And the sheet according to the present invention comprises the microcapsules according to the present invention and a binder resin or comprises the microcapsules according to the present invention and a base material. And the electrophoretic display according to the present invention has as a constitutional portion a portion which includes opposite electrode films and the microcapsules according to the present invention, wherein at least either one of the opposite electrode films is transparent, and wherein the microcapsules are disposed between the opposite electrode films.
A hair treatment composition which comprises 0.01-5.0 wt % of a particulate substance which is substantially unagglomerated or unaggregated prior to incorporation in the composition, which particulate substance has a modal primary particle size of 7-40 nm, and a Youngs modulus of at least 4 Gpa, preferably at least 6 GPa.
Described are flavor composition, flavor component, perfume composition and perfume component-containing microparticles which are particulate matrices composed of: (a) an olfactorily active component (e.g., perfume component); (b) silica; and (c) a saccharide composition which is a mixture of mannitol and maltose. The microparticles are useful in augmenting, enhancing and/or imparting aroma and/or taste (over relatively long periods of time in a controllably releasable manner) to perfume compositions, perfumed articles (e.g., deodorancy and antiperspirant sticks), foodstuffs, chewing gums, beverages and the like. Also described is a process for preparing the above-mentioned microparticles using, in sequence, (1) adsorption of the olfactorily active material onto silica followed by (2) a blending/extrusion step followed by (3) at least one particularization step.
