Storage-stable two-component silicone adhesives and sealants with extended mixer open time
A two-component silicone composition that includes a component A that includes i) at least one hydroxyl-group-terminated polydiorganosiloxane P; ii) at least one catalyst K for the cross-linking of polydiorganosiloxanes; and a component B that includes i′) at least one cross-linking agent for polydiorganosiloxanes. Compositions can be used as adhesives, sealants, coatings or as casting compounds and can be distinguished by a very long shelf life.
1. A two-component silicone composition, comprising:
a component A that comprises
i) at least one hydroxyl-group-terminated polydiorganosiloxane P;
ii) at least one catalyst K for the cross-linking of polydiorganosiloxanes; and
a component B that comprises
i′) at least one cross-linking agent for polydiorganosiloxanes,
wherein the weight ratio of component A to component B is 3:1 to 15:1.
2. The two-component silicone composition according to claim 1 , wherein the hydroxyl-group-terminated polydiorganosiloxane P is a polydiorganosiloxane P′ of Formula (I):
wherein, in the Formula (I),
each of radicals R 1 and R 2 , independently of one another, represents a linear or branched, monovalent hydrocarbon radical comprising 1 to 12 C atoms, which optionally comprises one or more heteroatoms and optionally one or more C—C multiple bonds and/or optionally cycloaliphatic and/or aromatic portions; and
n is selected in such a way that a weight mean of the molecular weight M w of the polydiorganosiloxane P′ relative to polystyrene is 500 to 250,000 g/mol.
3. The two-component silicone composition according to claim 2 , wherein the hydroxyl-group-terminated polydiorganosiloxane P′ is a polydiorganosiloxane P1 of Formula (I), wherein n is selected in such a way that the weight mean of the molecular weight M w of the polydiorganosiloxane P1 relative to polystyrene is 30,000 to 80,000 g/mol; or in such a way that a mixture of
i″) at least one hydroxyl-group-terminated polydiorganosiloxane P2 of Formula (I), wherein n is selected in such a way that the weight mean of the molecular weight M w of the polydiorganosiloxane P2 relative to polystyrene is >80,000 to 250,000 g/mol; and
ii″) at least one hydroxyl-group-terminated polydiorganosiloxane P3 of Formula (I), wherein n is selected in such a way that the weight mean of the molecular weight M w of the polydiorganosiloxane P3 relative to polystyrene is 500 to ≦80,000 g/mol, is used as polydiorganosiloxane P′.
4. The two-component silicone composition according to claim 3 , wherein the radicals R 1 and R 2 represent alkyl radicals with 1 to 5 C atoms.
5. The two-component silicone composition according to claim 1 , wherein the cross-linking agent for polydiorganosiloxanes is a silane of Formula (II):
wherein the radical R 3 , independently of one another, represents a linear or branched, monovalent hydrocarbon radical with 1 to 12 C atoms, which optionally has one or more heteroatoms and optionally one or more C—C multiple bonds and/or optionally cycloaliphatic and/or aromatic portions;
the radical R 4 , independently of one another, represents a hydrogen atom, or an alkyl radical with 1 to 12 C atoms, or an oxime radical with 1 to 12 C atoms, or an acyl radical with 1 to 12 C atoms; and
p represents a value of 0 to 4, provided that if p represents a value of 3 or 4, at least p−2 radicals R 3 in each case have at least one group that can be condensed and is reactive with the hydroxyl groups of the polydiorganosiloxane P.
6. The two-component silicone composition according to claim 5 , wherein p represents a value of 0.
7. The two-component silicone composition according to claim 6 , wherein the radical R 4 represents an alkyl radical with 1 to 5 C atoms.
8. The two-component silicone composition according to claim 1 , wherein the component B does not contain any polymerizable polydiorganosiloxanes.
9. The two-component silicone composition according to claim 1 , wherein the catalyst K is an organotin compound or a titanate.
10. The two-component silicone composition according to claim 1 , further comprising at least one adhesion promoter.
11. A method of forming a cured silicone composition from the two-component silicone composition according to claim 1 , comprising mixing component A with component B.
12. A method for extending the mixer open time with a uniform pot life or a simultaneous shortening of the pot life of a two-component silicone composition, comprising providing the two-component silicone composition of claim 1 , and mixing component A with component B.
13. The two-component silicone composition according to claim 4 , wherein the radicals R 1 and R 2 represent alkyl radicals with 1 to 3 C atoms.
14. The two-component silicone composition according to claim 4 , wherein the radicals R 1 and R 2 represent methyl groups.
15. The two-component silicone composition according to claim 7 , wherein the radical R 4 represents an alkyl radical with 1 to 3 C atoms.
16. The two-component silicone composition according to claim 7 , wherein the radical R 4 represents a methyl group or an ethyl group.
17. The two-component silicone composition according to claim 1 , wherein the weight ratio of component A to component B is 10:1 to 13:1.
18. The two-component silicone composition according to claim 10 , wherein the at least one adhesion promoter comprises an organoalkoxysilane that has amino groups.