Curing rubber by hydrosilation
A method for preparing a thermoplastic vulcanizate, the method comprising dynamically vulcanizing a rubber within a blend that includes the rubber and a thermoplastic polymer, where said dynamically vulcanizing is effected with a cure system that includes a hydrosilating agent and a catalyst, where the hydrosilating agent includes a compound including at least 3 silicon hydride groups defined by the formula where each R is independently a monovalent organic group or hydrogen, and where the silicon atoms of the respective silicon hydride groups are spatially separated by at least 6 atoms.
1. A method for preparing a thermoplastic vulcanizate, the method comprising:
dynamically vulcanizing a rubber within a blend that excludes functionalized resins and includes the rubber and a thermoplastic polymer at a temperature above the melting point of the thermoplastic polymer, where the rubber includes an olefinic elastomeric copolymer including one or more diene units deriving from 5-ethylidene-2-norbornene, where said dynamically vulcanizing is effected with a cure system that includes a hydrosilating agent and a catalyst, where the hydrosilating agent includes a compound including at least 3 silicon hydride groups defined by the formula
where each R is independently a monovalent organic group or hydrogen, and where the silicon atoms of the respective silicon hydride groups are spatially separated by at least 6 atoms, where the ratio of equivalents of silicon hydride groups associated with the hydrosilating agent to the equivalents of vinyl double bonds associated with the rubber is from about 0.7:1 to about 10:1.
2. The method of claim 1 , where each R is independently selected from an alkyl group.
3. The method of claim 2 , where the hydrosilating agent is substantially devoid of silicon atoms positioned in groups defined by the formulae
where each R 1 independently includes a monovalent organic group or hydrogen.
4. The method of claim 1 , where the hydrosilating agent is defined by the formula
where each R is independently a monovalent organic group, where αis a moiety containing a sufficient number of atoms to allow each of the SiH-containing groups to be spatially separated by at least 6 atoms, and x is an integer of at least 3.
5. The method of claim 4 , where the hydrosilating agent is devoid of any silicon atoms positioned in groups defined by the formulae
where each R 1 independently includes a monovalent organic group or hydrogen.
6. The method of claim 1 , where the hydrosilating agent includes at least 3 substituents defined by the formula
where each R is independently a monovalent organic group or hydrogen and each R 2 is independently a monovalent organic group or a silicon-containing moiety.
7. The method of claim 1 , where the hydrosilating agent includes a substituent defined by the formula
8. The method of claim 1 , where the hydrosilating agent includes less than 20% of its silicon atoms positioned in groups defined by the formulae
where each R 1 independently includes a monovalent organic group or hydrogen.
9. The method of claim 1 , where the catalyst includes a group VIII metal.
10. The method of claim 1 , where the catalyst is selected from the group consisting of chloroplatinic acid, elemental platinum, chloroplatinic acid hexahydrate, complexes of chloroplatinic acid with sym-divinyltetramethyldisiloxane, dichioro-bis(triphenylphosphine) platinum (II), cis-dichloro-bis(acetonitrile) platinum (II), dicarbonyldichloroplatinum (II), platinum chloride, and platinum oxide, zero valent platinum metal complexes, solid platinum supported on a carrier, platinum-vinylsiloxane complexes platinum-phosphine complexes, and platinum-phosphite complexes, RhCl(PPh 3 ) 3 , RhCl 3 , Rh/Al 2 O 3 , RuCl 3 , IrCl 3 , FeCl 3 , AlCl 3 , PdCl 2 .2H 2 O, NiCl 2 , TiCl 4 , and mixtures thereof.
11. The method of claim 1 , where the ratio of equivalents of silicon hydride groups associated with the hydrosilating agent to the equivalents of vinyl double bonds associated with the rubber is from about 0.95:1 to about 7:1.
12. The method of claim 11 , where the ratio of equivalents of silicon hydride groups associated with the hydrosilating agent to the equivalents of vinyl double bonds associated with the rubber is from about 1.5:1 to about 4:1.
13. The method of claim 1 , where the amount of catalyst present is from about 0.00007 parts by weight to about 0.069 parts by weight per 100 parts by weight rubber.
14. The method of claim 1 , where the olefinic elastomeric copolymer includes at least 3% by weight units deriving from 5-ethylidene-2-norbornene.
15. The method of claim 1 , where the rubber includes a second rubber including one or more units deriving from 5-vinyl-2-norbornene, or where the rubber includes a second rubber that is a tetrapolymer including units deriving from both 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene.
16. The method of claim 1 , where the amount of catalyst present is from about 0.0001 to about 0.0005 parts by weight per 100 parts by weight rubber.
17. The method claim 1 , where the amount of catalyst present is from about 0.0005 to about 0.001 parts by weight per 100 parts by weight rubber.
18. The method of claim 1 , where said step of dynamically vulcanizing the rubber cures the rubber to an extent where not more than 10 wt % rubber is extractable in cyclohexane at 23° C.
19. The method of claim 1 , where said step of dynamically vulcanizing the rubber cures the rubber to an extent where not more than 5 wt % rubber is extractable in cyclohexane at 23° C.
20. The method of claim 1 , where the olefinic elastomeric copolymer includes at least 4% by weight units deriving from 5-ethylidene-2-norbornene.
21. The method of claim 1 , where the olefinic elastomeric copolymer includes from about 5 to about 12% by weight units deriving from 5-ethylidene -2-norbornene.
22. The method of claim 1 , where the amount of catalyst present is from about 0.0001 to about 0.0005 parts by weight per 100 parts by weight rubber, where said step of dynamically vulcanizing the rubber cures the rubber to an extent where not more than 10 wt % rubber is extractable in cyclohexane at 23° C., and where the olefinic elastomeric copolymer includes at least 4% by weight units deriving from 5-ethylidene-2-norbornene.
23. The method of claim 22 , where the olefinic elastomeric copolymer consists essentially of units deriving from ethylene, units deriving from α-olefin, and 5-ethylidene-2-norbornene units.
24. The method of claim 23 , where the olefinic elastomeric copolymer is selected from the group consisting of ethylene-propylene rubber, propylene-based rubbery copolymers, and ethylene-based plastomers.
25. The method claim 1 , where the amount of catalyst present is from about 0.0005 to about 0.001 parts by weight per 100 parts by weight rubber, where said step of dynamically vulcanizing the rubber cures the rubber to an extent where not more than 5 wt % rubber is extractable in cyclohexane at 23° C., and where the olefinic elastomeric copolymer includes from about 5 to about 12% by weight units deriving from 5-ethylidene -2-norbornene.
26. The method of claim 25 , where the olefinic elastomeric copolymer consists essentially of units deriving from ethylene, units deriving from α-olefin, and 5-ethylidene-2-norbornene units.
27. The method of claim 1 , where the thermoplastic polymer has a melt temperature from about 110° C. to about 250° C.
28. The method of claim 27 , wherein the thermoplastic polymer is polypropylene.
29. A thermoplastic vulcanizate prepared by:
dynamically vulcanizing a rubber within a blend that excludes functionalized resins and includes the rubber and a thermoplastic polymer at a temperature above the melting point of the thermoplastic polymer, where the rubber includes an olefinic elastomeric copolymer including one or more diene units deriving from 5-ethylidene-2-norbornene, where said dynamically vulcanizing is effected with a cure system that includes a hydrosilating agent and a catalyst, where the hydrosilating agent includes a compound including at least 3 silicon hydride groups defined by the formula
where each R is independently a monovalent organic group or hydrogen, where the silicon atoms of the respective silicon hydride groups are spatially separated by at least 6 atoms, where the ratio of equivalents of silicon hydride groups associated with the hydrosilating agent to the equivalents of vinyl double bonds associated with the rubber is from about 0.7:1 to about 10:1.