Silylated Polyurethanes, Their Preparation and Use

A process for preparing a silylated polyurethane comprising the following steps:

• (a) reacting at least one polyol with at least one triisocyanate to form a hydroxyl-terminated polyurethane prepolymer;
• and
• (b) reacting the hydroxyl-terminated polyurethane prepolymer with at least one isocyanatosilane of formula (1) to endcap the hydroxyl groups on the hydroxyl-terminated polyurethane prepolymer with the isocyanatosilane,
• OCN—R—Si—(X)m(R1)3-m (1)
• wherein
• m is 0, 1 or 2,
• each R1 is independently from each other a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, or —OCH(R2)COOR3, wherein R2 is hydrogen or an alkyl group having 1 to 4 carbon atoms and R3 is a straight-chain or branched alkyl group having 1 to 8 carbon atoms,
• each X is independently from each other an optionally substituted hydrocarbon group having 1 to 10 carbon atoms, which can be interrupted by at least one heteroatom, and
• R is a difunctional organic group.

A silylated polyurethane that is the reaction product of a mixture comprising:

• (a) the hydroxyl terminated polyurethane prepolymer reaction product of a mixture comprising at least one polyol and at least one triisocyanate;
• and
• (b) at least one isocyanatosilane of formula (1)
• OCN—R—Si—(X)m(R1)3-m (1)
• wherein
• m is 0, 1 or 2,
• each R1 is independently from each other a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, or —OCH(R2)COOR3, wherein R2 is hydrogen or an alkyl group having 1 to 4 carbon atoms and R3 is a straight-chain or branched alkyl group having 1 to 8 carbon atoms,
• each X is independently from each other an optionally substituted hydrocarbon group having 1 to 10 carbon atoms, which can be interrupted by at least one heteroatom, and
• R is a difunctional organic group.