| 摘要 |
<p>Disclosed is a two-part polyurethane structural adhesive and method of bonding structural components, that exhibits at least 25 minutes of open time at 32° C. in large beads and cures to high strength under ambient conditions. The adhesive composition in one part is an isocyanate or isocyanate prepolymer and in a second part is a polyol mixture (I) or (II), wherein 75% to 100% by weight of the polyol mixture (I) or (II) are polyols having secondary hydroxyl functionality and the polyol mixture (I) or (II) contains a long chain secondary polyol defined hereinbelow. The polyol mixture in one embodiment is substantially absent short chain polyols having functionality of 2, and includes an amount from 30% to 80 % by weight on total polyol weight in (I) of long chain secondary polyol of molecular weight from 2000 to 12000 and from 20% to 70% by weight on total weight of the polyol mixture and of a short chain secondary polyol with functionality greater than 2 and a molecular weight of from 90 to 800. In another embodiment, 5% to 80% of a long chain secondary polyol of molecular weight of from 2000 to 12000 is present together with 5% to 70% of a short chain secondary polyol having a functionality of greater than 2, and 5% to 70% of a short chain secondary polyol having a functionality of 2 and a molecular weight of from 90-800.</p> |
