Fast-curing composition containing silane groups
A polymer preparation consisting of silane-functional polymers, including at least one polymer having at least one terminal group of formula (I) and at least one further silane terminal group, a method for producing the polymer preparation and a composition containing it. The polymer preparation has a surprisingly low viscosity, cross-links surprisingly quickly even without the use of EHS-critical catalysts such as organotin compounds or DBU, and hardens into a non-sticky material with good strength and elasticity. It is especially well suited as an elastic adhesive or sealant or as an elastic coating. The invention further relates to a method for lowering the viscosity of a polymer having at least one terminal group of formula (I) by introducing at least one further silane terminal group.
1. A polymer formulation comprising at least one silane-functional polymer having at least one end group of the formula (I)
where
R 1a , R 1b , R 1c and R 1d are each independently a hydrogen atom or a monovalent hydrocarbyl radical having 1 to 12 carbon atoms, or in pairs are each an alkylene radical having 2 to 6 carbon atoms,
R 2 is a hydrogen atom or a monovalent hydrocarbyl radical which has 1 to 12 carbon atoms and optionally contains ether groups, ester groups, nitrile groups, amino groups or silane groups,
R 3 is a linear or branched alkylene or cycloalkylene radical having 1 to 20 carbon atoms, optionally having aromatic components, and optionally having one or more heteroatoms,
R 4 is an alkyl radical having 1 to 8 carbon atoms,
R 5 is an alkyl radical which has 1 to 10 carbon atoms and optionally contains ether groups,
x is 0 or 1 or 2,
m is 0 or 1, and
n is 0 or 1 or 2 or 3 or 4 or 5, where n, if m is 1, is 1 or 2 or 3 or 4;
and at least one further silane end group that does not correspond to the formula (I).
2. The polymer formulation as claimed in claim 1 , wherein the silane-functional polymers are polyethers and/or polyesters and/or polycarbonates containing silane groups.
3. The polymer formulation as claimed in claim 1 , wherein the silane-functional polymers overall have an average molecular weight in the range from 1,000 to 30,000 g/mol.
4. The polymer formulation as claimed in claim 1 , wherein m is 0, n is 0, R 1a is a methyl radical and R 1b is a hydrogen atom.
5. The polymer formulation as claimed in claim 1 , wherein m is 0, n is 2, R 1a is a methyl radical or is an n-butyl radical, and R 1b , R 1c and R 1d are each a hydrogen atom.
6. The polymer formulation as claimed in claim 1 , wherein m is 1, n is 1, R 1a is a methyl radical, and R 1b , R 1c and R 1d are each a hydrogen atom.
7. The polymer formulation as claimed in claim 1 , wherein the further silane end group is an end group of the formula (II)
where
R 6 is a linear or branched alkylene or cycloalkylene radical having 1 to 20 carbon atoms, optionally having aromatic components,
R 7 is an alkyl radical having 1 to 8 carbon atoms,
R 8 is an alkyl radical which has 1 to 10 carbon atoms and optionally contains ether groups, and
y is 0 or 1 or 2.
8. The polymer formulation as claimed in claim 1 , wherein the further silane end group is an end group of the formula (III)
where
R 9 is a methyl radical or an ethyl radical and
z is 0 or 1 or 2.
9. The polymer formulation as claimed in claim 1 , wherein the silane-functional polymers overall have a ratio between the number of end groups of the formula (I) and the number of further silane end groups in the range from 99/1 to 5/95.
10. A process for producing the polymer formulation as claimed in claim 1 , comprising the steps of
providing a polymer containing at least one hydroxyl group and at least one silane end group which does not correspond to the formula (I) as first intermediate;
reacting the first intermediate with at least one diisocyanate at an NCO/OH ratio of more than 1 to give a second intermediate; and
reacting the second intermediate with at least one hydroxysilane of the formula (VI) at an NCO/OH ratio of not more than 1
11. The process as claimed in claim 10 , wherein the first intermediate is prepared by reacting
at least one polyol with at least one isocyanatosilane of the formula (IV) at an NCO/OH ratio of less than 1
or
at least one polyol having allyl groups with at least one hydrosilane of the formula (V) with hydrosilylation of the allyl groups
wherein
R 6 is a linear or branched alkylene or cycloalkylene radical having 1 to 20 carbon atoms, optionally having aromatic components,
R 7 is an alkyl radical having 1 to 8 carbon atoms,
R 8 is an alkyl radical which has 1 to 10 carbon atoms and optionally contains ether groups,
R 9 is a methyl radical or an ethyl radical,
y is 0 or 1 or 2, and
z is 0 or 1 or 2.
12. A composition comprising at least one polymer formulation as claimed in claim 1 .
13. The composition as claimed in claim 12 , wherein it has a content of silane-functional polymers in the range from 5% to 95% by weight.
14. The method for adhesively bonding, sealing or coating a substrate or surface comprising applying and subsequently curing the composition as claimed in claim 12 to said substrate or surface.
15. A method of lowering the viscosity of a polymer having at least one end group of the formula (I) comprising introducing at least one further silane end group that does not correspond to the formula (I)
where
R 1a , R 1b , R 1c and R 1d are each independently a hydrogen atom or a monovalent hydrocarbyl radical having 1 to 12 carbon atoms, or in pairs are each an alkylene radical having 2 to 6 carbon atoms,
R 2 is a hydrogen atom or a monovalent hydrocarbyl radical which has 1 to 12 carbon atoms and optionally contains ether groups, ester groups, nitrile groups, amino groups or silane groups,
R 3 is a linear or branched alkylene or cycloalkylene radical having 1 to 20 carbon atoms, optionally having aromatic components, and optionally having one or more heteroatoms,
R 4 is an alkyl radical having 1 to 8 carbon atoms,
R 5 is an alkyl radical which has 1 to 10 carbon atoms and optionally contains ether groups,
x is 0 or 1 or 2,
m is 0 or 1, and
n is 0 or 1 or 2 or 3 or 4 or 5, where n, if m is 1, is 1 or 2 or 3 or 4.