Dow Corning Corporation

Keith E Polmanteer

David P Jones

Ronald E Kittle

John K Fitzgerald

Harry L Chapman

Arthur A Birdsall

The compression set values of cured elastomers prepared from finely divided organosiloxane elastomer bases are reduced by treating the base with a silane or disilazane wherein the silicon atoms are bonded to one hydrolyzable group and three hydrocarbon radicals that are free of ethylenic unsaturation. The base is maintained in a fluidized state during this treatment.

Method for preparing a finely divided, free flowing organosiloxane

This invention provides heat curable compositions comprising a high viscosity, peroxide curable polydiorganosiloxane, a relatively low viscosity liquid diorganoalkenylsiloxy endblocked polydiorganosiloxane, a reinforcing filler and an effective amount of a vinyl specific organic peroxide. The tensile and recovery properties of the cured elastomer are optimized when the concentration of diorganoalkenylsiloxy groups on the liquid polydiorganosiloxane relative to the concentration of repeating units in the peroxide curable polydiorganosiloxane is within specified limits.

High strength, heat curable polyorganosiloxane elastomer compositions

Optically clear silicone compositions comprising 100 parts by weight of at least one polydiorganosiloxane and 15 to 120 parts by weight of a hydrophobic reinforcing silica filler wherein substantially all of the surface-treated silica filler particles are sufficiently small in their largest dimensions such that a uniform 2.54 mm thickness of the composition possesses a haze value of less than 4% and a luminous transmittance value of at least 85% according to ASTM D1003-61. The refractive index of the polydiorganosiloxane does not have to be matched with that of the silica filler to obtain optically clear compositions. The haze value of certain of such compositions does not increase by more than 1% per 2.54 mm thickness when the composition is heated from 23.degree..+-.2.degree. C. to 100.degree..+-.5.degree. C. Optionally, curing agents and other additives can be present in the compositions. Optically clear cured elastomers useful as lenses or tubing can be prepared from such elastomers. Methods for the preparation of such compositions are also claimed.

Optically clear silicone compositions curable to elastomers

Silicone rubber articles that are resistant to abrasion, permeation of gases and accumulation of dirt particles have an adherant coating on at least one surface of the article. The coating is derived from a peroxide-curable fluoroelastomer gum composition which contains (1) an epoxide compound in an amount sufficient to react with the acidic by-products generated during curing of the elastomer, and (2) an organic peroxide in an amount sufficient to achieve curing of the fluoroelastomer gum at elevated temperatures.

Fluoroelastomer coated silicone rubber

Optical devices such as corneal, scleral and interocular lenses are made from phenyl-containing siloxane resins. They combine a high degree of oxygen transmission with ease of fabrication inherent to hard materials, thereby providing increased wearer comfort and ease of fabrication. A typical resin is a copolymer of phenyl, vinyl and methyl siloxanes having at least about 0.2 phenyl groups per silicon.

Silicone resin optical devices

A hydrophilic, water-swellable, crosslinked gel is produced by copolymerizing a water soluble vinylic constituent in aqueous solution with olefinic hydrolyzable silanes which contain low molecular weight alkoxy groups. Copolymerization is via the unsaturated groups and crosslinking is by condensation reactions. The copolymer is swellable to a finite extent or to an infinite extent depending upon the water/vinylic monomer volume ratio and upon the vinylic monomer:silane mole ratio. Non-toxic embodiments of the gel are especially useful as prosthesis fillers. Such gels can be used to fill the prosthesis before implantation or the prosthesis can be swollen with an aqueous solution after implantation.

Hydrophilic, water-swellable, crosslinked, copolymer gel and prosthesis

A sponge prepared from silicone rubber using 4,4'-oxybis(benzenesulfonhydrazide) as a blowing agent has improved heat stability when calcium oxide, magnesium oxide or a mixture of these two oxides is present in the composition. The sponge prepared using these oxides has a lower compression deflection after heat aging than the compositions which do not contain the oxides.

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Midland, MI, United States of America

Keith E Polmanteer