Isocyanate-free expandable mixtures exhibiting a fast hardening rate
Isocyanate-free foamable mixtures suitable for filling construction voids and for other uses, comprise isocyanate-free, alkoxysilane-terminated prepolymers (A) which have a silane end group of the formula [1], where X and Y are each an oxygen atom, an N—R 3 group or a sulfur atom, R 1 is an alkyl, cycloalkyl, alkenyl or aryl radical having 1-10 carbon atoms, R 2 is an alkyl radical having 1-2 carbon atoms or an ω-oxyalkylalkyl radical having a total of 2-10 carbon atoms, R 3 is a hydrogen atom, an alkyl, alkenyl or aryl radical having 1-10 carbon atoms or a —CH 2 —SiR 1 z (OR 2 ) 3-z group, and z is 0 or 1, with the proviso that at least one of the two groups X and Y is an NH function, and (B) blowing agents.
1. An isocyanate-free moisture-curable foamable mixture comprising
(A) one or more isocyanate-free, alkoxysilane-terminated prepolymers (A) which bear at least one silane end group of the formula [1],
where
X is O and Y
is NH or where X is NH and Y is NR 3 ,
R 1 is an alkyl, alkenyl or aryl radical having 1-10 carbon atoms,
R 2 is an alkyl radical having 1-2 carbon atoms or an -oxyalkyl alkyl radical having a total of 2-10 carbon atoms,
R 3 is a hydrogen atom, an alkyl, cycloalkyl, alkenyl or aryl radical having 1-10 carbon atoms or a —CH 2 —SiR 1 z (OR 2 ) 3-z group and
z is 0 or 1,
with the proviso that at least one of the two groups X and Y is NH, and
(B) at least one blowing agent.
2. The foamable mixture of claim 1 , wherein a prepolymer (A) has silane end groups of the formula [2]
3. The foamable mixture of claim 1 , wherein the blowing agent (B) is selected from the group consisting of hydrocarbons and fluorinated hydrocarbons each having 1-5 carbon atoms, dimethyl ether, and mixtures thereof.
4. The foamable mixture of claim 1 , wherein at least one low molecular weight reactive diluent (C) which has a viscosity of not more than 5 Pas at 20° C. and has at least one C 1 -C 6 -alkoxysilyl group per molecule is present in the mixture.
5. The foamable mixture of claim 4 , wherein at least one reactive diluent (C) is selected from the group consisting of methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, and their partial hydrolysis products, and is present in a concentration of >1% by weight, based on the weight of prepolymer(s) (A).
6. The foamable mixture of claim 1 , wherein R 1 is a methyl, ethyl or phenyl group.
7. The foamable mixture of claim 4 , wherein R 1 is a methyl, ethyl or phenyl group.
8. The foamable mixture of claim 1 , wherein R 2 is a methyl group.
9. The foamable mixture of claim 4 , wherein R 2 is a methyl group.
10. The foamable mixture of claim 6 , wherein R 2 is a methyl group.
11. The foamable mixture of claim 1 , wherein R 3 is a hydrogen atom, an alkyl radical having 1-4 carbon atoms, a cyclohexyl radical or a phenyl radical.
12. The foamable mixture of claim 4 , wherein R 3 is a hydrogen atom, an alkyl radical having 1-4 carbon atoms, a cyclohexyl radical or a phenyl radical.
13. The foamable mixture of claim 6 , wherein R 3 is a hydrogen atom, an alkyl radical having 1-4 carbon atoms, a cyclohexyl radical or a phenyl radical.
14. The foamable mixture of claim 8 , wherein R 3 is a hydrogen atom, an alkyl radical having 1-4 carbon atoms, a cyclohexyl radical or a phenyl radical.
15. The foamable mixture of claim 1 , which, after foaming, has a tack-free time of not more than 5 minutes at 20° C.
16. The foamable mixture of claim 1 which is free of tin catalysts.
17. The foamable mixture of claim 1 , which is free of catalysts containing heavy metals.
18. The foamable mixture of claim 1 , comprising a prepolymer prepared by addition of a silane of the formula [3]
onto an alcohol having at least two OH functions per molecule and which comprises branched or unbranched hydrocarbon chains which may be substituted by halogen atoms, C 1 -C 6 -alkyl, -alkoxy or -acyloxy radicals, optionally interrupted by groups selected from the group consisting of ether groups, carbonyl groups, ester groups, aromatic groups, cycloaliphatic groups, and mixtures thereof, wherein the alcohol contains no urethane or urea groups.
19. A pressurized container containing the foamable mixture of claim 1 .
20. The foamable mixture of claim 1 , wherein a prepolymer (A) has silane end groups selected from the group consisting of:
21. An isocyanate-free moisture-curable foamable mixture comprising
(A) one or more isocyanate-free, alkoxysilane-terminated prepolymers (A) which bear at least one silane end group of the formula [1],
where
X is O and Y is NH or where X is NH and Y is NR 3 ,
R 1 is an alkyl, alkenyl or aryl radical having 1-10 carbon atoms,
R 2 is an alkyl radical having 1-2 carbon atoms or an -oxyalkyl alkyl radical having a total of 2-10 carbon atoms,
R 3 is an alkyl, cycloalkyl, alkenyl or aryl radical having 1-10 carbon atoms and
z is 0 or 1, and
(B) at least one blowing agent.
22. The foamable mixture of claim 1 , wherein the blowing agent comprises dimethyl ether.
23. The foamable mixture of claim 1 , wherein X is O and Y is NH.
24. The foamable mixture of claim 1 , wherein X is NH and Y is NR 3 .