Claims
- 1. A cured elastomer composition obtained by cross-linking an uncured blend composition that comprises an intimately admixed mixture that includes the following components:
- (1) approximately 23 to 45 percent by weight of silica that had been silyliated by treatment and contains trialkylsilyl groups;
- (2) approximately 55 to 77 per cent by weight of a polysiloxane copolymer composed of divalent --R.sub.1 R.sub.2 SiO--, divalent --R.sub.3 R.sub.4 SiO-- and end-blocking R.sub.5 R.sub.6 R.sub.7 SiO-- units,
- where R.sub.1 and R.sub.2 independently are lower alkyl of 1 to 6 carbons, phenyl or trifluoropropyl, R.sub.3 is vinyl, allyl, or other olefinic group having up to 4 carbons, R.sub.4 is lower alkyl of 1 to 6 carbons, phenyl or trifluoropropyl, and R.sub.5, R.sub.6, and R.sub.7 independently are lower alkyl of 1 to 6 carbons, phenyl, vinyl, allyl, or other olefinic group having up to 4 carbons and one double bond, the polysiloxane copolymer has a degree of polymerization (D. P.) approximately in the range of 3500 to 6500, and the olefin containing --R.sub.3 R.sub.4 SiO-- groups are present randomly distributed in the polysiloxane copolymer and approximately in the 0.05 to 0.3 mol percent range, with the provisos that when R.sub.1, or R.sub.2, or both represent phenyl groups then proportion of the phenyl-containing divalent siloxane units does not exceed 15 mol per cent and when R.sub.1 or R.sub.2 or both represent trifluoropropyl groups, then the proportion of the trifluoropropyl-containing divalent siloxane units does not exceed approximately 40 mol per cent in the polysiloxane copolymer;
- (3) a catalyst, and
- (4) an organohydrogen polysiloxane cross-linker,
- the catalyst and the cross-linker being present in the uncured blend composition in sufficient amount to cause the cross-linking reaction to occur.
- 2. The cured elastomer composition of claim 1 wherein the --R.sub.1 R.sub.2 SiO-- group is --(CH.sub.3).sub.2 SiO--.
- 3. The cured elastomer composition of claim 1 wherein the --R.sub.3 R.sub.4 SiO-- group is --CH.sub.3 (CH.sub.2 .dbd.CH)SiO--.
- 4. The cured elastomer composition of claim 1 wherein the R.sub.5 R.sub.6 R.sub.7 SiO-- group is --(CH.sub.3).sub.2 (CH.sub.2 .dbd.CH)SiO--.
- 5. The cured elastomer composition of claim 1 wherein the --R.sub.1 R.sub.2 SiO-- group is --(CH.sub.3).sub.2 SiO--, the --R.sub.3 R.sub.4 SiO-- group is --CH.sub.3 (CH.sub.2 .dbd.CH)SiO--, and the R.sub.5 R.sub.6 R.sub.7 SiO-- group is --(CH.sub.3).sub.2 (CH.sub.2 .dbd.CH)SiO--.
- 6. The cured elastomer composition of claim 5 where the --CH.sub.3 (CH.sub.2 .dbd.CH)SiO-- group is present in the polysiloxane copolymer in the proportion of 0.142 mol percent.
- 7. The cured elastomer composition of claim 1 where the silyliated silica includes trimethylsilyl groups in such quantity that the carbon content of the silica is in the range of approximately 4 to 8 per cent by weight.
- 8. The cured elastomer composition of claim 7 where the carbon content of the silyliated silica is approximately 7.3 per cent by weight.
- 9. The cured elastomer composition of claim 8 where the silyliated silica is present in the cured elastomer in the proportion of approximately 39 per cent by weight.
- 10. The cured elastomer composition of claim 1 where the catalyst is a platinum catalyst.
- 11. The cured elastomer composition of claim 1 where the organohydrogen polysiloxane cross-linker has the formula (R).sub.a (H).sub.b SiO.sub.2-a/2-b/2 where R is simple lower alkyl and "a" ranges from 1.00 to 3, and "b" ranges from 0.1 to 1.0.
- 12. An uncured elastomer blend composition suitable for curing by cross linking, the composition comprising two aliquots in combination:
- the first aliquot comprising an intimately admixed mixture of the following components:
- (1) approximately 23 to 45 percent by weight of silica that had been silyliated by treatment and contains trialkylsilyl groups;
- (2) approximately 55 to 77 per cent by weight of a polysiloxane copolymer composed of divalent --R.sub.1 R.sub.2 SiO--, divalent --R.sub.3 R.sub.4 SiO-- and end-blocking R.sub.5 R.sub.6 R.sub.7 SiO-- units,
- where R.sub.1 and R.sub.2 independently are lower alkyl of 1 to 6 carbons, phenyl or trifluoropropyl, R.sub.3 is vinyl, allyl, or other olefinic group having up to 4 carbons, R.sub.4 is lower alkyl of 1 to 6 carbons, phenyl or trifluoropropyl, and R.sub.5, R.sub.6, and R.sub.7 independently are lower alkyl of 1 to 6 carbons, phenyl, vinyl, allyl, or other olefinic group having up to 4 carbons and one double bond, the polysiloxane copolymer has a degree of polymerization (D. P.) approximately in the range of 3500 to 6500, and the olefin containing --R.sub.3 R.sub.4 SiO-- groups are present randomly distributed in the polysiloxane copolymer and approximately in the 0.05 to 0.3 mol percent range, with the provisos that when R.sub.1, or R.sub.2, or both represent phenyl groups then proportion of the phenyl-containing divalent siloxane units does not exceed 15 mol per cent. and when R.sub.1 or R.sub.2 or both represent trifluoropropyl groups, then the proportion of the trifluoropropyl-containing divalent siloxane units does not exceed approximately 40 mol per cent in the polysiloxane copolymer; and a
- (3) a catalyst,
- the second aliquot comprising an intimately admixed mixture of the following components:
- (1) approximately 23 to 45 percent by weight of silica that had been silyliated by treatment and contains trialkylsilyl groups;
- (2) approximately 55 to 77 per cent by weight of a polysiloxane copolymer composed of divalent --R.sub.1 R.sub.2 SiO--, divalent --R.sub.3 R.sub.4 SiO-- and end-blocking R.sub.5 R.sub.6 R.sub.7 SiO-- units,
- where R.sub.1 and R.sub.2 independently are lower alkyl of 1 to 6 carbons, phenyl or trifluoropropyl, R.sub.3 is vinyl, allyl, or other olefinic group having up to 4 carbons, R.sub.4 is lower alkyl of 1 to 6 carbons, phenyl or trifluoropropyl, and R.sub.5, R.sub.6, and R.sub.7 independently are lower alkyl of 1 to 6 carbons, phenyl, vinyl, allyl, or other olefinic group having up to 4 carbons and one double bond, the polysiloxane copolymer has a degree of polymerization (D. P.) approximately in the range of 3500 to 6500, and the olefin containing --R.sub.3 R.sub.4 SiO-- groups are present randomly distributed in the polysiloxane copolymer and approximately in the 0.05 to 0.3 mol percent range, with the provisos that when R.sub.1, or R.sub.2, or both represent phenyl groups then proportion of the phenyl-containing divalent siloxane units does not exceed 15 mol per cent, and when R.sub.1 or R.sub.2 or both represent trifluoropropyl groups, then the proportion of the trifluoropropyl-containing divalent siloxane units does not exceed approximately 40 mol per cent in the polysiloxane copolymer, and
- (3) an organohydrogen polysiloxane cross-linker,
- the catalyst and the cross-linker being present in the first and second aliquots respectively in sufficient amounts to cause the cross-linking reaction to occur after the first and second aliquots are intimately mixed.
- 13. The uncured elastomer blend composition of claim 12 wherein in the polysiloxane copolymer of each aliquot the --R.sub.1 R.sub.2 SiO-- group is --(CH.sub.3).sub.2 SiO--, the --R.sub.3 R.sub.4 SiO-- group is --CH.sub.3 (CH.sub.2 .dbd.CH)SiO--, and the R.sub.5 R.sub.6 R.sub.7 SiO-- group is --(CH.sub.3).sub.2 (CH.sub.2 .dbd.CH)SiO--.
- 14. The uncured elastomer blend composition of claim 13 wherein in the polysiloxane copolymer of each aliquot the silyliated silica includes trimethylsilyl groups in such quantity that the carbon content of the silica is in the range of approximately 4 to 8 per cent by weight.
- 15. The uncured elastomer blend composition of claim 12 wherein the second aliquot further comprises a volatile inhibitor in such quantity that the cross-linking reaction occurs rapidly after intimately mixing the first and second aliquots and substantially removing the inhibitor by heat.
Parent Case Info
This application is a division of application Ser. No. 08/697,991, filed Sep. 4, 1996, now abandoned.
US Referenced Citations (10)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0110537 |
Jun 1984 |
EPX |
0579132 |
Jan 1994 |
EPX |
Non-Patent Literature Citations (1)
Entry |
Kazemi-Shirazi H et al: "New Silicone Rubbers, 2 Biocompatible Silicone Rubbers", Angewandte Makromolekulare Chemie, vol.205, Feb. 1, 1993, pp. 193-201, XP000345380. |
Divisions (1)
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Number |
Date |
Country |
Parent |
697991 |
Sep 1996 |
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