ALKOXYSILANE-GROUP MODIFIED POLYURETHANES AND LOW MODULUS SEALANTS FORMED THEREFROM
Disclosed are alkoxysilane-group modified polyurethane that are the reaction product of: (1) a polyoxyalkylene diol; and (2) an isocyanate-functional silane. Also disclosed are compositions, including sealant compositions, that include such polyurethanes, and cured sealant formed from such compositions.
1 . An alkoxysilane-group modified polyurethane that is the reaction product of:
(1) a polyoxyalkylene polyol having a molecular weight of at least 18,000 gram/mole, a polydispersity of less than 1.5 and a content of unsaturated end groups of no more than 0.02 meq/gram polyol, measured according to ASTM D2849-69; and
(2) a compound of the formula:
ONC—Y—Si—(X) 3 ,
wherein: (i) each X independently represents identical or different alkoxy radicals, and (ii) Y represents a difunctional organic radical, and wherein a weight average molar ratio of isocyanate groups of (2) to hydroxyl groups of (1) used to make the polyurethane is less than 0.80:1.
2 . The alkoxysilane-group modified polyurethane of claim 1 , wherein the polyoxyalkylene polyol is a diol.
3 . The alkoxysilane-group modified polyurethane of claim 1 , wherein the polyoxyalkylene polyol has a molecular weight of greater than 20,000 g/mol to 30,000 g/mol.
4 . The alkoxysilane-group modified polyurethane of claim 3 , wherein the polyoxyalkylene polyol has a molecular weight of 21,000 g/mol to 25,000 g/mol.
5 . The alkoxysilane-group modified polyurethane of claim 1 , wherein the weight average molar ratio of isocyanate groups of (2) to hydroxyl groups of (1) used to make the polyurethane is no more than 0.76:1.
6 . The alkoxysilane-group modified polyurethane of claim 5 , wherein the weight average molar ratio of isocyanate groups of (2) to hydroxyl groups of (1) used to make the polyurethane is 0.5 to 0.76:1.
7 . The alkoxysilane-group modified polyurethane of claim 1 , wherein the polyoxyalkyene polyol has a content of unsaturated end groups of no more than 0.01 meq/gram diol, measured according to ASTM D2849-69.
8 . (canceled)
9 . The alkoxysilane-group modified polyurethane of claim 8 , wherein the polydispersity is 1.05 to 1.15.
10 . A composition comprising:
(i) 10 to 50 percent by weight, based on the total weight of the composition, of the alkoxysilane-group modified polyurethane of claim 1 ; and
(ii) 0 to 15 percent by weight, based on the total weight of the composition, of an inert plasticizer.
11 . The composition of claim 10 , further comprising:
(b) 20 to 60 percent by weight of a filler, based on the total weight of the composition.
12 . A cured sealant produced from the composition of claim 10 , wherein the sealant has a modulus at 100% extension of no more than 0.41 MPa when measured according to ASTM D412, Method A.
13 . A moisture curable composition comprising:
(a) an alkoxysilane-group modified polyurethane comprising a reaction product of:
(1) a polyoxyalkylene polyol having a molecular weight of at least 18,000 gram/mole, a polydispersity of less than 1.5, and a content of unsaturated end groups of no more than 0.07 meq/gram diol, measured according to ASTM D2849-69; and
(2) a compound of the formula:
ONC—Y—Si—(X) 3 ,
wherein: (i) each X independently represents identical or different alkoxy radicals, and (ii) Y represents a difunctional organic radical, and
wherein a weight average molar ratio of isocyanate groups of (2) to hydroxyl groups of (1) used to make the polyurethane is less than 0.80:1;
(b) a filler; and
(c) 0 to 15% by weight, based on the total weight of the composition, of an inert plasticizer.
14 . The composition of claim 13 , wherein the polyoxyalkyene polyol is a diol.
15 . The composition of claim 14 , wherein the polyoxyalkyene polyol has a content of unsaturated end groups of no more than 0.01 meq/gram diol, measured according to ASTM D2849-69.
16 . The composition of claim 13 , wherein the molecular weight is 21,000 to 25,000 gram/mole.
17 . The composition of claim 13 , wherein the weight average molar ratio of isocyanate groups of (2) to hydroxyl groups of (1) used to make the polyurethane is no more than 0.76:1.
18 . A cured sealant produced from the composition of claim 13 , wherein the sealant has a modulus at 100% extension of no more than 0.41 MPa when measured according to ASTM D412, Method A.
19 . A cured sealant having a modulus at 100% extension of no more than 0.41 MPa when measured according to ASTM D412, Method A, wherein the cured sealant is produced from a composition comprising:
(a) an alkoxysilane-group modified polyurethane comprising a reaction product of:
(1) a polyoxyalkylene polyol having a molecular weight of at least 18,000 gram/mole and a polydispersity of less than 1.5; and
(2) a compound of the formula:
ONC—Y—Si—(X) 3 ,
wherein: (i) each X independently represents identical or different alkoxy radicals, and (ii) Y represents a difunctional organic radical, and
wherein a weight average molar ratio of isocyanate groups of (2) to hydroxyl groups of (1) used to make the polyurethane is less than 0.80;
(b) a filler; and
(c) 0 to 15% by weight, based on the total weight of the composition, of an inert plasticizer.
20 . The cured sealant of claim 19 , wherein the polyoxyalkyelene polyol is a diol.