Cross-linkable polymer blends containing alkoxysilane-terminated polymers
View Patent ↗Alkoxysilane-terminated polymers prepared by reacting an isocyanatoalkoxysilane, preferably an isocyanatodialkyalkoxysilane, with an isocyanate-reactive prepolymer, can provide chain extension even when a monoalkoxy-functional silane, while retaining suitable reactivity profiles. The products are useful in sealants, caulks, coatings, and moldings.
1. A crosslinkable polymer blend, comprising at least one polymer A having endgroups of the formula (1)
-L-CH 2 —SiR 1 a (OR 2 ) 3-a (1)
wherein
L is a divalent linking group selected from —O—CO—NH—, —N(R 3 )—CO—NH—, —S—CO—NH—,
R 1 is an optionally halogen-substituted alkyl, cycloalkyl, alkenyl or aryl radical having 1–10 carbon atoms,
R 2 is an alkyl radical having 1–6 carbon atoms or an ω-oxyalkylalkyl radical having a total of 2–10 carbon atoms,
R 3 is hydrogen, an optionally halogen-substituted cyclic, linear or branched C 1 to C 18 alkyl or alkenyl radical or a C 6 to C 18 aryl radical, and
a is an integer from 0 to 2,
with the proviso that the fraction of the endgroups of the general formula (1) where a=2, relative to all the endgroups of the polymers present in the mixture which have alkoxysilane endgroups, is from 5% to 100%.
2. The polymer blend of claim 1 , wherein the fraction of the endgroups of the general formula (1) where a=2, relative to all the endgroups of the polymers present in the polymer mixture which have alkoxysilane endgroups, is at least 50%.
3. The polymer blend of claim 1 , wherein the radicals R 1 are independently methyl, ethyl or phenyl radicals.
4. The polymer blend of claim 2 , wherein the radicals R 1 are independently methyl, ethyl or phenyl radicals.
5. The polymer blend of claim 1 , wherein the radicals R 2 are independently methyl or ethyl radicals.
6. The polymer blend of claim 2 , wherein the radicals R 2 are independently methyl or ethyl radicals.
7. The polymer blend of claim 3 , wherein the radicals R 2 are independently methyl or ethyl radicals.
8. The polymer blend of claim 1 , further comprising at least one organic amino compound as a basic catalyst (B).
9. The polymer blend of claim 3 , further comprising at least one organic amino compound as a basic catalyst (B).
10. The polymer blend of claim 5 , further comprising at least one organic amino compound as a basic catalyst (B).
11. In an adhesive, sealant, coating, or moldable elastomer which is moisture curable and which contains a blend of one or more alkoxysilane-functional polymers, the improvement comprising selecting as said blend, a crosslinkable polymer blend of claim 1 .
12. In an adhesive, sealant, coating, or moldable elastomer which is moisture curable and which contains a blend of one or more alkoxysilane-functional polymers, the improvement comprising selecting as said blend, a crosslinkable polymer blend of claim 2 .
13. In an adhesive, sealant, coating, or moldable elastomer which is moisture curable and which contains a blend of one or more alkoxysilane-functional polymers, the improvement comprising selecting as said blend, a crosslinkable polymer blend of claim 3 .
14. In an adhesive, sealant, coating, or moldable elastomer which is moisture curable and which contains a blend of one or more alkoxysilane-functional polymers, the improvement comprising selecting as said blend, a crosslinkable polymer blend of claim 5 .
15. In an adhesive, sealant, coating, or moldable elastomer which is moisture curable and which contains a blend of one or more alkoxysilane-functional polymers, the improvement comprising selecting as said blend, a crosslinkable polymer blend of claim 8 .
16. A process for the preparation of an alkoxysilane-functional polymer suitable for use in the crosslinkable polymer blend of claim 1 , said process comprising reacting at least one isocyanatosilane of the formula (2)
OCN—CH 2 —SiR 1 a (OR 2 ) 3-a (2)
with one or more prepolymers having at least one terminal isocyanate-reactive end group selected from the group consisting of OH, HNR 3, and HS,
wherein
R 1 is an alkyl radical having 1 to 6 carbon atoms or an ω-oxyalkyl radical having a total of 2 to 10 carbon atoms; and
a is an integer from 0 to 2,
with the proviso that the fraction of the isocyanatosilanes of the formula (2) where a=2 relative to all isocyanatosilanes which bear SiR 1 a (OR 2 ) 3-a groups is from 5% to 100%.
17. The process of claim 16 wherein said prepolymer is a linear polymer selected from the group consisting of polysiloxanes, polysiloxane-urea/urethane copolymers, polyurethanes, polyureas, polyethers, polyesters, poly(meth)acrylates, polycarbonates, polystyrenes, polyamindes, polyvinyl esters, styrene/butadiene copolymers, and polyolefins.
18. The process of claim 17 wherein said prepolymer is α, ω-bis-terminated with a single type of isocyanate reactive end group.
19. A crosslinkable blend comprising at least one alkoxysilane-functional polymer prepared by the process of claim 16 .