General Electric Company

Robert A Smith

Gary M Lucas

Melvin D Beers

Mary A White

Roger T Swiger

Theresa A Garafalo

John J Fitzgerald

Philip J McDermott

Richard A Striker

Brian J Ward

Michael A Zumbrum

Richard P Surprenant

Paul J Caradori

Bruce C Kuhl

A method for preparing the first component of a two-component room temperature-vulcanizable (RTV) silicone composition comprises (a) preparing a filler/oil masterbatch by (i) adding an unreactive silicone oil and untreated, aggregated filler particles to a mixer; (ii) adding a filler treating agent such as an organosilane, a polyorganosilane or a silazane to the unreactive silicone oil/filler mixture; and (iii) mixing the unreactive silicone oil/filler mixture and treating agent under conditions sufficient to breakdown the aggregated filler particles to an average size of less than about 300 nm for a time of less than about 24 hours to form the filler/oil masterbatch; and (b) adding said filler/oil masterbatch to a reactive silicone oil.

Filler/silicone oil masterbatch with treating agent for RTV polysiloxanes

A process for treating fillers, preferably precipitated silica, to improve the physical property profile of heat curable and room temperature vulcanizable silicone rubbers and a composition for room temperature vulcanizable rubbers comprising the silica filler treated by the process of the invention.

Treating process for precipitated silica fillers

Condensation curable silicone mold making compositions containing an olefin or acetylene polymerization inhibitor have a longer useful life for making casts from curable resins comprising a polymerizable olefin relative to compositions where such a polymerization inhibitor is absent. Particularly preferred polymerization inhibitors are the esters of thiodipropionic acid and silicon polysulfides.

Silicone molding compositions having extended useful life

Secondary contact adhesion or self-bonding in cured liquid injection molding silicone compositions is reduced by the inclusion in the composition of an inhibitor compound selected from the group consisting of phenyl fluids, titanate esters, and silicate esters.

Heat curable elastomeric compositions

Silicone mold compositions are provided which exhibit low durometer and high tear strength properties and comprise a main filler of precipitated silica and a reinforcing co-filler selected from acicular CaSiO.sub.3 fillers, fumed aluminum oxide fillers, and spherical ceramic fillers. The co-fillers have large surface areas and small particle sizes. The co-fillers are used with alkoxy silane cross-linking agents of the formula (RO).sub.4 Si, particularly n-propylsilicate. Two-part silicone cure systems are provided which enable the rapid achievement of full die B tear strengths without the need for prolonged aging of these materials.

Molding compounds having low durometer and high tear strength

Stable, substantially acid-free, one package moisture curable polyalkoxy-terminated organopolysiloxane compositions are provided having a condensation catalyst such as a tin compound. A method for making the aforesaid moisture curable organopolysiloxane compositions, is also provided.

One package, stable, moisture curable, polyalkoxy-terminated

A self-bonding solventless room temperature vulcanizable silicone rubber composition comprising a silanol polymer, a resinous copolymer composed of monofunctional siloxy units and tetrafunctional siloxy units, an alkyl silicate or partial hydrolysis products of an alkyl silicate as a cross linking agent which is pre-reacted with a tin salt of a carboxylic acid, and as a self-bonding additive, a nitrogen functional silane. This composition which can be made either clear or opaque is utilized with advantage for encapsulating photovoltaic cells and potting automotive electrical components.

Completely solventless two component RTV silicone composition

A two-component room temperature vulcanizable polysiloxane composition curable in the presence of a heat-activated catalyst is disclosed. The working life of a condensation curable organopolysiloxane containing terminal silicon-bonded hydroxy groups in a first component is extended by using a metallic salt of an organic carboxylic acid catalyst in a second component by providing in combination with the metallic salt of an organic carboxylic acid catalyst, a solid, inert barrier material capable of melting at an elevated temperature, whereby the catalyst is activated when heat applied thereto, melts the solid barrier material. A cross-linking agent and optionally, a filler, are used in the components. In one embodiment, the catalyst is a tin carboxylate used as a core material and the solid, inert barrier material is calcium stearate used as a wall material to encapsulate the catalyst material.

Room temperature vulcanizable polysiloxane having a heat-activated

Two-part room-temperature vulcanizing silicone dental impression compositions are provided which, before curing, consist essentially of a metallic salt of a monocarboxylic acid as a catalyst and a base compound. In one embodiment the base compound consists of a fluid diorganopolysiloxane, an organosilicon cross-linker and a unique filler combination of an admixture of zinc oxide, calcium carbonate and pumice. In another embodiment, the base compound consists of a fluid diorganopolysiloxane, an organosilicon cross-linker, mineral oil and a low oil absorption calcium carbonate filler.

Silicone dental impression compositions

A process and composition for producing a cross-linking agent component for two-component room temperature vulcanizable silicone rubber compositions comprising the reaction product of 25 to 75 parts of a silicate selected from the class consisting of alkyl silicates of the formula,

Cross-linking agents for room temperature vulcanizable silicone rubber

Stable catalyst compositions providing faster cure time in room temperature vulcanizing organopolysiloxane compositions containing them comprise stannous salts of branched chain alkyl carboxylic acids having from eight to 12 carbon atoms and, as a stabilizing carrier therefor, a methyl alkyl polysiloxane fluid having hydroxy aryl substituents. The catalyst compositions are uniquely adapted to provide injectable compositions curable to low density, high compressive strength syntactic foams, useful, e.g., for custom fitting footwear to the wearer.

Catalyst composition for room temperature vulcanizing silicone

Stable catalyst compositions providing faster cure time in room temperature vulcanizing organopolysiloxane compositions containing them comprise stannous salts of branched chain alkyl carboxylic acids having from 8 to 12 carbon atoms and, as a stabilizing carrier therefor, a methyl alkyl polysiloxane fluid having hydroxy aryl substituents. The catalyst compositions are uniquely adapted to provide injectable compositions curable to low density, high compressive strength syntactic foams, useful, e.g., for custom fitting footwear to the wearer.

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Schenectady, NY, United States of America

Robert A Smith