| 摘要 |
Liquid phenol-aldehyde (preferably phenol-formaldehyde) resole resins are cured and foamed by the addition of at least 5 and preferably not more than 20 parts by weight of AlCl3 or AlBr3 per hundred parts of resin, preferred concentrations being such as to cause self curing of the mixture, though heat may also be used. Foaming may be assisted by the addition of e.g. 2-50% by weight of the resole of organic foaming agents having boiling points of about -40-200 DEG F., care being taken to avoid reducing the viscosity of the mixture below 200 centipoises. Preferred blowing agents are the halogenated fluorohydrocarbons of copending Specificatio 1,087,056. Mixtures of blowing agents may be used. The usual surface-active agents may be included and other possible additives include the glycidyl ethers of polyhydric phenols, and polyols and polyisocyanates. |
