High temperature sealant containing phenyl silicone

A high temperature sealant tape, useful in autoclave curing and processing of thermosetting and thermopalstic composites, comprising:

• (a) a release liner;
• (b) a semisolid sealant disposed on the release liner which sealant comprises:
• (i) about 40 to 90 wt-% of a silicone having a molecular weight of about 10,000 to 10,000,000 and repeating units comprising:
• (a) about 1 to 20 mole-% of units having the formula ##STR12## wherein R comprises --H, a C.sub.1-5 alkyl group, a C.sub.1-5 fluoroalkyl group, a vinyl group or a phenyl group and
• (B) about 99 to 80 mole-% of units having the formula:
• ##STR13## wherein each R independently comprises --H, a C.sub.1-5 alkyl group, a C.sub.1-5 fluoroalkyl group, or a vinyl group;
• and
• (ii) about 1 to 10 wt-% of a thermal stabilizer;
• (iii) about 0.1 to 2 wt-% of a peroxide curing agent that acts upon alkyl substituents on the silicone chain resulting in alkylene groups that combine to crosslink;
• and
• (iv) about 0 to 50 wt-% of an inorganic filler;
• wherein the tape remains effective at temperatures above about 700.degree. F.

An organic solvent-free high temperature sealant tape, useful in vacuum thermoforming, comprising:

• (a) a release liner;
• (b) a semisolid sealant disposed on the release liner, which sealant comprises.
• (i) about 95 Wt-% of a composition comprising about 81 wt-% of a silicone having the general formula ##STR14## wherein R equals about 95% methyl and about 5% phenyl substituents and x is about 100 to 100,000, and about 19% of an inorganic silica based filler;
• (ii) about 4 wt-% of an iron oxide thermal stabilizer;
• and
• (iii) about 1 wt-% of a dicumyl peroxide curing agent that acts upon alkyl substituents on the silicone chain resulting in alkylene groups that combine to crosslink;
• wherein the tape remains effective at temperatures above about 700.degree. F. and exhibits room temperature tack.