Inhibitor for platinum catalyzed silicone rubber compositions
AssigneeGeneral Electric Company
InventorWilliam J. Bobear
Life of this patent
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Abstract
A platinum catalyzed silicone rubber composition with an improved work life having as its base constituents 100 parts of a vinyl-containing polysiloxane where the vinyl concentration is at least 0.005 mole percent, at least 0.1 parts per million of a platinum catalyst and from 1 to 50 parts based on 100 parts of the vinyl-containing polysiloxane of a hydrogen-containing polysiloxane and further having as an inhibitor additive a compound with at least one radical of the formula, --C--O--O--H the preferred inhibitor compounds containing the hydroperoxy radical are tertiary butyl hydroperoxide, methylethylketone hydroperoxide, cumene hydroperoxide, 1,1,3,3,-tetramethylbutyl hydroperoxide and 2,5-dimethyl-2,5-dihydroperoxyhexane.
Claims34
A platinum catalyzed silicone rubber composition with an improved work life comprising (a) 100 parts by weight of a vinyl-containing base linear polysiloxane of the formula,
- R.sub.a SiO.sub.4-a/2
- and blends of such polysiloxanes, where R is selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, vinyl radicals, phenyl radicals, fluoroalkyl radicals of 3 to 10 carbon atoms and mixtures thereof, where the vinyl radical unsaturation in said polymer is at least 0.005 mole percent, a varies from 1.98 to 2.01, (b) at least 0.1 parts per million of platinum, (c) from 1 to 50 parts by weight of a hydrogen-containing polysiloxane, and (d) at least 0.007 parts by weight of an inhibitor compound having at least one radical of the formula, -- C -- O -- O -- H, per 100 parts of said vinyl-containing polymer.
A process for forming a silicone composition which in the uncured state and at room temperature has a controlled work life comprising (A) mixing (a) 100 parts by weight of a vinyl-containing base linear polysiloxane of the formula,
- R.sub.a SiO.sub.4-a/2
- and blends of such polysiloxanes where R is selected from the class consisting of alkyl radicals of 1 to 8 carbon atoms, vinyl radicals, phenyl radicals, fluoroalkyl radicals of 3 to 10 carbon atoms and mixtures thereof where the vinyl radical concentration in polysiloxanes is at least 0.005 mole percent, a varies from 1.98 to 2.01 with (b) at least 0.1 parts per million of platinum, and (c) from 1 to 50 parts by weight of a hydride compound which is a hydrogen-containing polysiloxane and (d) at least 0.007 parts by weight of an inhibitor compound having at least one radical -- C -- O -- O -- H per 100 parts of said vinyl-containing polymer and (b) allowing the composition to cure.
Dependencies are inferred from the claim text.