Polyester prepolymers
The invention relates to prepolymers containing alkoxysilane groups based on special, low-viscosity polyester polyols, which exhibit particularly high tensile strength, a process for the production thereof and their use as a binder for adhesives, primers or coatings.
1. Alkoxysilane group-containing polyurethanes of the general formula (I),
wherein
PES is a residue of a polyester polyol with 2-3 OH groups, reduced by the OH groups, at least 90 wt.% of which (based on acid and alcohols) was produced from adipic acid and a mixture of at least 20 wt.% each (based on the mixture) of butanediol or hexanediol and neopentyl glycol, having a number-average molecular weight (Mn) of between 500 g/mol and 2500 g/mol,
c =1 or 2,
X represents the same or different alkoxy or alkyl residues, which may also be bridged, provided that at least one alkoxy residue is present on each Si atom,
Q is a difunctional, linear or branched, aliphatic residue.
2. An adhesive, coating or primer which comprising at least one alkoxysilane group-containing polyurethane according to claim 1 .