Raychem Limited

Catherine A Dittmer

Robert S Dubrow

William D Uken

Carib Nelson

This invention provides for the radiation grafting of certain organopolysiloxanes to polymeric supports. The organopolysiloxane material is partially crosslinked mixture which contains from about 10% to about 90% by weight of uncrosslinked organopolysiloxane oil and has a cone penetration of about 100 to about 350 (10.sup.-1 mm) and an ultimate elongation of at least about 100%. The organopolysiloxane fluid may be placed on the polymeric support and crosslinked to produce an organopolysiloxane material having the above properties and being bonded to the polymeric support. The organopolysiloxane material also can be crosslinked to the above properties by conventional means then placed in contact with the polymeric support and irradiated to crosslink the material to the polymeric support without substantially changing the properties of the organopolysiloxane material.

Radiation grafting of organopolysiloxanes

This invention provides new heat transfer materials comprising gels and particulate fillers and having a composite heat transfer coefficient greater than 2 watts/m-.degree. K. and preferably greater than 15. The materials are easily conformable to irregularly shaped surfaces and have low TO-3 thermal impedance values, e.g., less than 0.5 at 300 psi mounting pressure.

Thermally conductive gel materials

The present invention provides novel curable organopolysiloxane composition comprising at least about 50% by weight of a general organopolysiloxane having no more than two vinyl groups and up to about 50% by weight of a crosslink additive which is a polysiloxane having at least three vinyl groups and is copolymerizable with the organopolysiloxane. This curable composition when cured by heat, chemical or, preferably, radiation curing techniques produces crosslinked polysiloxane materials having unique combinations of cone penetration, elongation and tensile strength properties. A preferred use for these materials is as a sealant.

Curable organopolysiloxane composition

An article for protecting a substrate includes a preshaped member having a shape similar to that of the substrate being protected, the article having a thin layer of gel disposed in intimate contact with an inner surface of the member such that the gel is disposed in intimate contact with the substrate when the member is disposed therearound. Preferably, the gel comprises an open looped three-dimensional network, the gel being relatively soft, elastic, and having an ultimate elongation in excess of 100%.

Protective article

This invention provides organopolysiloxane materials having cone penetration between about 100 and about 350 (10.sup.-1 mm) and ultimate elongation of at least 100% and having reduced surface tack. This invention provides three methods of obtaining said materials with reduced surface tack. The first method comprises applying to the surface of such material an organic peroxide or a photoinitiator and irradiating the surface with ultraviolet light to further crosslink the surface to reduce or eliminate the tack of the surface. The second method comprises mixing a photoinitiator, such as benzophenone, in an organopolysiloxane fluid, thermally crosslinking the organopolysiloxane fluid to produce the material with the above cone penetration and ultimate elongation then irradiating the surface of the material with ultraviolet light to reduce or eliminate the tack of the surface. The third method comprises mixing a photoinitiator, such as benzophenone, in an organopolysiloxane fluid, crosslinking the fluid by irradiating a layer of the fluid with ultraviolet light to produce the above cone penetration and ultimate elongation properties then further irradiating the crosslinked material to reduce or eliminate the surface tack; this method can be carried out by simultaneous irradiation with ultraviolet light from two sides of a layer of the organopolysiloxane wherein one surface is irradiated at a higher intensity than the other surface. The materials produced by this invention are useful as tapes and sealants.

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Mountain View, CA, United States of America

Catherine A Dittmer