Peroxide-curable fluorosilicone copolymer compositions

Claim 2

A peroxide-curable silanol-endstopped or alkenyl-endstopped diorganopolysiloxane copolymer having a molecular weight of from about 400,000 to about 600,000 comprising units of the formulae RR'SiO and R" 2 SiO, wherein R is fluoroalkyl of from 3 to 8 carbon atoms, R' is alkyl of from 1 to 8 carbon atoms, alkenyl of from 2 to 8 carbon atoms, or phenyl, and wherein sufficient RR'SiO units are present to provide about 45-65 mole percent fluorosilicone content and sufficient R" 2 SiO units containing alkenyl substituents are present to provide a vinyl content along the polysiloxane chain of about 0.02 weight percent to about 0.5 weight percent as CH 2 ═CH--.

Claim 3

A copolymer as defined in claim 1, wherein R is 3,3,3-trifluoropropyl, R' is methyl, and R" is methyl or vinyl.

Claim 4

A copolymer as defined in claim 2, wherein sufficient R" groups are vinyl to provide 0.02-0.2 weight percent vinyl content along the polysiloxane chain.

Claim 5

A curable fluorosilicone composition comprising (A) a silanol-endstopped or alkenyl-endstopped diorganopolysiloxane copolymer having a molecular weight of from about 400,000 to about 600,000 comprising units of the formulae RR'SiO and R" 2 SiO, wherein R is fluoroalkyl of from 3 to 8 carbon atoms, R' is alkyl of from 1 to 8 carbon atoms or phenyl, and each R" is, independently, alkyl of from 1 to 8 carbon atoms, alkenyl of from 2 to 8 carbon atoms, or phenyl, and wherein sufficient RR'SiO units are present to provide about 45-65 mole percent fluorosilicone content and sufficient R" 2 SiO units containing alkenyl substituents are present to provide a vinyl content along the polysiloxane chain of from about 0.02 weight percent to about 0.5 weight percent as CH 2 ═CH--; and (B) a peroxide curing catalyst.

Claim 6

A curable fluorosilicone composition comprising (A) a silanol-endstopped or alkenyl-endstopped diorganopolysiloxane copolymer having a molecular weight of from about 400,000 to about 600,000 comprising units of the formulae RR'SiO and R" 2 SiO, wherein R is fluoroalkyl of from 3 to 8 carbon atoms, R' is alkyl of from 1 to 8 carbon atoms or phenyl, and each R" is, independently, alkyl of from 1 to 8 carbon atoms, alkenyl of from 2 to 8 carbon atoms, or phenyl, and wherein sufficient RR'SiO units are present to provide about 45-65 mole percent fluorosilicone content and sufficient R" 2 SiO units containing alkenyl substituents are present to provide a vinyl content along the polysiloxane chain of from about 0.02 weight percent to about 0.5 weight percent as CH 2 ═CH--; and (B) a peroxide curing catalyst.

Claim 7

A curable composition as defined in claim 4, wherein said peroxide curing catalyst is an organic peroxide compound in which at least 1 peroxide oxygen is attached to a tertiary carbon atom.

Claim 8

A curable composition as defined in claim 5, wherein R is 3,3,3-trifluoropropyl, R' is methyl, and R" is methyl or vinyl.

Claim 9

A curable composition as defined in claim 6, wherein said organic peroxide compound is present in an amount from about 0.01% to about 5.0% by weight.

Claim 10

A curable composition as defined in claim 7, wherein sufficient R" groups are vinyl so as to provide 0.02-0.2 weight percent vinyl content along the polysiloxane chain.

Claim 11

A curable composition as defined in claim 8, wherein said fluorosilicone content is in the range of 50-60 mole percent.

Claim 12

A curable composition as defined in claim 9, wherein said fluorosilicone content is in the range of 52-57 mole percent.

Claim 13

A curable composition as defined in claim 7, wherein said organic peroxide compound is 2,5-dimethyl-2,5-di-(t-butyl peroxy)hexane.

Claim 14

A curable composition as defined in claim 7, which is further compounded with a filler or combination of fillers.

Claim 15

A curable composition as defined in claim 12, wherein said filler is a silica filler treated with a diorganodihalogensilane hydrolyzate comprising mixed cyclic diorganopolysiloxanes and low molecular weight linear silanol-endstopped diorganopolysiloxanes.

Claim 16

A curable fluorosilicone composition comprising (A) a silanol-endstopped or vinyl-endstopped diorganopolysiloxane copolymer having a molecular weight of from 400,000 to about 600,000 comprising units of the formulae RR'SiO and R" 2 SiO, wherein R is fluoroalkyl of from 3 to 8 carbon atoms, R' is alkyl of from 1 to 8 carbon atoms, and each R" is, independently, alkyl of from 1 to 8 carbon atoms or vinyl, and wherein sufficient R-containing units are present to provide about 50-60 mole percent fluorosilicone content and sufficient vinyl-functional units are present to provide a vinyl content along the polysiloxane chain of about 0.02-0.5 weight percent as CH 2 ═CH--; (B) a peroxide curing catalyst in which at least one peroxide oxygen is attached to a tertiary carbon atom; and (C) cerium hydroxide.

Claim 17

A curable fluorosilicone composition comprising (A) a silanol-endstopped or vinyl-endstopped diorganopolysiloxane copolymer having a molecular weight of from 400,000 to about 600,000 comprising units of the formulae RR'SiO and R" 2 SiO, wherein R is fluoroalkyl of from 3 to 8 carbon atoms, R' is alkyl of from 1 to 8 carbon atoms, and each R" is, independently, alkyl of from 1 to 8 carbon atoms or vinyl, and wherein sufficient R-containing units are present to provide about 50-60 mole percent fluorosilicone content and sufficient vinyl-functional units are present to provide a vinyl content along the polysiloxane chain of about 0.02-0.5 weight percent as CH 2 ═CH--; (B) a peroxide curing catalyst in which at least one peroxide oxygen is attached to a tertiary carbon atom; and (C) cerium hydroxide.

Claim 18

A curable composition as defined in claim 14, wherein said vinyl content is from 0.02 to 0.2 weight percent.

Claim 19

A curable composition as defined in claim 15, wherein said curing catalyst is 2,5-dimethyl-2,5-di-(t-butyl peroxy)hexane.

Claim 20

A curable composition as defined in claim 15, which is further compounded with a silica filler treated with a diorganodihalogensilane hydrolyzate comprising mixed cyclic diorganopolysiloxanes and low molecular weight linear silanol-endstopped diorganopolysiloxanes.

Claim 21

A curable composition as defined in claim 17, which further comprises an organic silazane and a curing co-agent selected from trimethylol propane trimethacrylate, triallyl trimellitate, 1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane, and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane.

Claim 22

A curable composition as defined in claim 18, wherein said organic silazane is bis-dimethyl-vinyl silazane, and said curing co-agent is trimethylol propane trimethacrylate.