Polyurethane based adhesion composition and method

Claim 1

A one-component, moisture-curable sealant composition comprising a) a silane-terminated polyurethane polymer of the formula ##STR7## wherein U comprises a polyurethane containing at least two urethane linkages per molecule, prepared from polyether polyols having at least two free hydroxyl groups; R is a lower alkyl of from 1 to 6 carbon atoms; R 1 is a divalent bridging radical selected from the group consisting of divalent hydrocarbon radicals, divalent hydrocarbon ether radicals, and divalent hydrocarbon amino radicals; A is selected from the group consisting of --S-- and --NR 2 -- where R 2 is selected from the group consisting of hydrogen and an alkyl of from one to six carbon atoms; and (b) a substituted silane electrocoat adhesion promoter comprising a silane compound of the formula ##STR8## wherein R 3 , R 4 and R 5 may be the same or different and are selected from alkyl and alkoxyl of from one to four carbon atoms, and wherein B is at least one member selected from the group consisting of: ##STR9## wherein x is an integer of from one to six, wherein R 7 is an alkyl group of from one to four carbon atoms or alkylene of one to four carbon atoms, and wherein y and z may be the same or different and are integers of from one to six, said adhesion promoter being present in an amount between 2.0 and 8.5 parts by weight based on 100 parts of polyurethane polymer.