Alkoxysilane-terminated, moisture-hardening polyurethanes and their use in adhesives and sealing compositions

A process for the preparation of an alkoxysilane-terminated, moisture-hardening polyurethane comprising the steps of

• (a) reacting at least one OH-terminated linear diol or triol with at least one diisocyanate to form an NCO-terminated polyurethane having a number average NCO functionality of at least 2,
• (b) reacting some of the NCO-groups on the polyurethane from step (a) with at least one linear or branched aliphatic alcohol containing from 1 to 18 carbon atoms or a monoalkylpolyalkylene glycol to form a polyurethane having a number average NCO functionality of at least 1 and less than 2, and
• (c) reacting substantially all the free NCO-groups in the polyurethane obtained from step (b) with at least one alkoxysilane corresponding to the formula ##STR5## in which X=--SH, --NHR.sup.2, R.sup.2 CH--CH--CH.sub.2 --O--,
• --(NH--CH.sub.2 --CH.sub.2).sub.n' --NHR.sup.2 ;
• n'=1 or 2;
• R=--CH.sub.3, --CH.sub.2 --CH.sub.3, or OR.sup.1 ;
• R.sup.1 =--(CH.sub.2 --CH.sub.2 --O).sub.m --R.sup.3 ;
• R.sup.2 =H or an aliphatic or cycloaliphatic or aromatic hydrocarbon radical containing from 1 to 10 carbon atoms and optionally substituted with one or more C.sub.1 -C.sub.3 alkyl and/or C.sub.1 -C.sub.3 alkoxy groups;
• R.sup.3 =an alkyl radical containing from 1 to 10 carbon atoms and optionally substituted with one or more C.sub.1 -C.sub.3 alkyl and/or C.sub.1 -C.sub.3 alkoxy groups;
• R.sup.4 =an alkyl radical containing from 1 to 4 carbon atoms;
• and
• n=1-8;
• m=1-30;
• p.gtoreq.1;
• and q+p=2.