| 摘要 |
Generally closed cell phenolic foams are prepared which have a K-factor of less than 0.029, watt/(m.K) preferably from 0.017 to 0.024 watt/(m.K) of foam thickness when mesured at 24<o> Centrigrade. The foams are prepared from a resole resin which has been stripped to a water level of less than 7 percent by weight, preferably from 3 to about 6 percent by weight based on resin weight. A viscosity adjusting amount of a solvent, such as phenol, and from 10 to 20 weight percent, based on resin weight, of a polyglycol are also part of a foam forming formulation. Conventional surfactants, blowing agents and acidic catalysts are used to prepare the foams. The foams so prepared generally have no tendency to autoxidize when placed in an oven heated to a temperature of 250<o> Centrigrade. The foams so prepared also have enhanced resistance to flame penetration. |
