| 摘要 |
<p>Self-extinguishing rigid polyurethane foams are prepd. by reacting the addn. cpds. of pref. 4 - 30 wt.% urea and 2 - 15 wt.% formaldehyde with 20 - 50 wt.% polyisocyanates in the pres. of 0 - 40 wt.% polyalcohols and water. The reaction mixture also conts. blowing agents and catalysts. These foams have excellent self-extinguishing props. and are used as thermal and sound insulation in buildings, tankers etc.</p> |
