Coated active agent-containing article
AssigneeDow Corning Corporation
InventorsJohn T. Woodard, Martin C. Musolf, Patrick J. Miller
Life of this patent
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Abstract
Aqueous coating compositions for forming elastomeric films around active cores (e.g., drugs) comprising a dispersion of pre-crosslinked polyorganosiloxane latex particles, colloidal silica particles, and a water-dispersible organic material (e.g., polyethylene glycol) are disclosed and claimed. The elastomeric films formed by the coating compositions are used to control the rate of release of an active agent in the cores into an aqueous environment. Methods of formulating the coating compositions and active cores coated with the coating compositions are also disclosed.
Claims14
An article comprising a core containing an active agent, said core being completely covered with a continuous cured elastomeric film formed from an aqueous coating composition, said active agent being releasable in a controlled manner through said cured film when the article is placed in a liquid environment, said composition comprising a dispersion of:
- A) polyorganosiloxane latex particles consisting essentially of a cross-linked reaction product of an oil-in-water emulsion of:
- i) 100 parts by weight of a polydiorganosiloxane polymer of the formula HO(R.sub.2 SiO).sub.x H;
- ii) 0.5 to 15 parts by weight of an alkoxy silicon compound selected from the group consisting of silanes of the formula R'.sub.a Si(OR").sub.4-a, a partial hydrolyzate of the silane where the partial hydrolyzate is soluble in said polydiorganosiloxane polymer, and mixtures of the silane and partial hydrolyzate;
- and
- iii) a quantity of anionic surfactant effective to both disperse said polydiorganosiloxane polymer in water and to catalyze the reaction of said alkoxy silicon compound with said polydiorganosiloxane polymer;
- where R is selected from the group consisting of phenyl, vinyl, alkyl, and 3,3,3-trifluoropropyl radicals, R' is a monovalent hydrocarbon radical having up to 12 carbon atoms, R" is an alkyl radical having 1 to 6, inclusive, carbon atoms, x has an average value in the range of from 3 to 100, inclusive, and a is 0 or 1;
- B) colloidal silica particles present as a dispersed phase in water;
- and
- C) a water-dispersible, organic material selected from the group consisting of polyvinylpyrrollidone and polyhydric alcohols and esters thereof;
- wherein for each 100 parts by weight of polyorganosiloxane latex particles (A) present in the dispersion, there is present from 5 to 50 parts by weight of colloidal silica (B), and between 8 and 100 parts by weight of water-dispersible material (C),
- and wherein the viscosity of the entire dispersion forming the aqueous coating composition is in a range which permits coating of the coating composition on said active core, and the dispersion forms a continuous, elastomeric film upon removal of the aqueous portion of said mixture and said film is free of any catalysts and other materials which are toxic to animals.
Dependencies are inferred from the claim text.