Intumescent silicone rubber composition
OwnerKeith I. Brebnerinventor
Life of this patent
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Abstract
An intumescent silicone rubber composition is provided having an expandable intumescent material present in the composition by up to 20% by weight, a polyorganosiloxane oil present in an amount from about 10% to about 40% by weight of the composition, a hydrated alkali metal silicate present in an amount of up to 80% by weight of the composition and a silicone elastomer binder present in an amount from about 4% to about 30% by weight of the composition. The result is a very effective and relatively inexpensive composition which when used as firestop material around combustible pipe, such as PVC or ABS, readily meets the test criteria set forth under ASTM Standard E-814.
Claims12
An intumescent composition which expands and forms a composite char on heating, comprising:
- an expandable intumescent graphite material being present in an amount up to 20% by weight of said composition;
- a polyorganosiloxane oil compound present in an amount from about 10% to about 40% by weight of said composition;
- a hydrated alkali metal silicate present in an amount of up to 80% by weight of said composition;
- and
- a silicone elastomer binder present in an amount from about 4% to about 30%, by weight of said composition;
- sufficient of said oil being present to soften said elastomer and accommodate the expansion;
- and said intumescent graphite material being present in an amount effective to reduce shrink-back due to the silicate on heating to form char.
An intumescent fire stop composition comprising:
- a hydrated alkali metal silicate expandable intumescent in an amount ranging from about 22 up to about 60% by weight of said composition, said silicate being subject to shrink-back at temperatures above 500.degree. C.;
- an expandable intumescent graphite, in an amount within the range of about 5 up to about 17% by weight of said composition and sufficient to reduce said shrink-back;
- a silicone elastomer in an effective binding amount from about 8 to about 30% by weight of said composition;
- and
- a polyorganosiloxane oil softener in an amount from about 20 to about 40% by weight of said composition, with amounts of oil softener being selected to soften the elastomer and permit the desired expansion.
Dependencies are inferred from the claim text.