Phenolic resin foam formation - using mixt. of blowing agents having different gas evolution temperatures

摘要

Phenolic resin foams are prepd. by incorporation into the resin before polymsn., of a mixt. of blowing agents which each forms a gas at different temps. between the initial and final polymerisation temps., the blowing agents being selected from (5-6)C acyclic hydrocarbons and fluorinated and/or chlorinated (m)ethane. Successive generations of gas during the reaction results in a more uniform cell structure, eliminates shrinkage and prevents internal cracking.