| 摘要 |
<p>A layer of sealant consisting of a liquid pre-polymer contg. free NCO gps. derived from reaction of a polyisocyanate and a polyol, and containing a finely-divided polyamine carbamate, is applied to the ring-shaped groove in the cap, and heated to decompose the polyamine carbamate and gel the sealant, which is then hardened at normal temp. and humidity. The polyol is pref. a mixt. contg. at least one diol and at least 30 wt.% of a triol, the diol pref. being poly (oxy-propylene) glycol and the triol poly(oxypropylene) triol. The polyamine carbamate is pref. the reaction product of a triamine and CO2. In addition to allowing parts with wider tolerances to be used, the time before testing the seal can be reduced from 5-6 h. to around 5 mins. and solvent vapours from the sealant are eliminated.</p> |
