| 摘要 |
<p>Foamed products are made from mixtures of bituminous materials (I) with phenols and hexamethylene tetramine condensed in the presence of an alkaline catalyst and aldehydes at temp. 140-200 degrees C for 4h. The expansion takes place under pressure at 165-180 degrees C using hexamethylene tetramine as blowing agent. I are asphalt, petroleum bitumens, pitch and cold tar in proportion 50-70% of bitumen plus phenols. Bitumen based foams are usually dimensionally unstable. The present process provides rigid foams much cheaper than other foams, with good compression strength. The foams do not contain free acid and are therefore noncorrosive to metals, and heat resistance is as good as straight phenolic foams.</p> |
