Silylated polyurethanes, their preparation and use

1. A silylated polyurethane having a viscosity of about 41,200 mPas to about 78,600 mPas and obtained by a process 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 (R 1 ) 3−m   (1)

wherein

m is 0, 1 or 2,

each R 1 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(R 2 )COOR 3 , wherein R 2 is hydrogen or an alkyl group having 1 to 4 carbon atoms and R 3 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.

2. The silylated polyurethane according to claim 1 , wherein a molar ratio of the NCO groups of the triisocyanate to hydroxyl groups of the polyol is from 0.05 to 0.45.

3. The silylated polyurethane according to claim 1 , wherein said polyol is a polyether polyol.

4. The silylated polyurethane according to claim 1 , wherein said polyol has a number average molecular weight of from 500 to 20,000 g/mol.

5. The silylated polyurethane according to claim 1 , wherein said triisocyanate is derived from HDI, TDI, MDI, PDI, IPDI, or mixtures thereof.

6. The silylated polyurethane according to claim 1 , wherein said isocyanatosilane is selected from the group consisting of 3-isocyanatopropyltrimethoxysilane, 2-isocyanatoisopropyltrimethoxysilane, 4-isocyanato-n-butyltrimethoxysilane, 2-isocyanato-1,1-dimethylethyltrimethoxysilane, 1-isocyanatomethyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 2-isocyanato-2-methylethyltriethoxysilane, 4-isocyanatobutyltriethoxysilane, 2-isocyanato-1,1-dimethylethyltriethoxysilane, 1-isocyanatomethyltriethoxysilane, 3-isocyanatopropylmethyld imethoxysilane, 3-isocyanatopropyldimethylmethoxysilane, 3-isocyanatopropylphenylmethylmethoxysilane, 1-isocyanatomethylmethyldimethoxysilane, 3-isocyanatopropylethyldiethoxysilane, 3-isocyanatopropylmethyldiethoxysilane, 1-isocyanatomethylmethyldiethoxysilane, and mixtures thereof.

7. The silylated polyurethane according to claim 1 , wherein said process comprises further step of adding a catalyst.

8. An adhesive, sealant, or coating composition comprising the silylated polyurethane according to claim 1 .

9. An adhesive, sealant, or coating composition comprising:

a silylated polyurethane: and

optionally one or more additives selected from catalyst, plasticizer, stabilizer, antioxidant, filler, reactive diluent, drying agent, adhesion promoter, UV stabilizer, fungicide, flame retardant, rheological adjuvant, color pigment, color paste, and solvent;

wherein the composition has a viscosity of 40,000 mPas to 150,000 mPas and the silylated polyurethane 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 (R 1 ) 3−m   (1)

wherein

m is 0, 1 or 2,

each R 1 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(R 2 )COOR 3 , wherein R 2 is hydrogen or an alkyl group having 1 to 4 carbon atoms and R 3 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.