Process for manufacturing closed cell phenolic foams

This invention relates to the manufacture of closed cell phenolic foams from low viscosity phenol-­formaldehyde resole resin. This method of manufacture provides a foam which exhibits many of the advantageous characteristics of phenolic foams manufactured from high viscosity resole resin, including good thermal retention. There is provided a method of making a phenolic foam comprising the steps of mixing (a) a phenol-formaldehyde resole resin having a water content of approximately 7.5% and a viscosity of approximately 2,800 cps at 40°C;(b) a high molecular weight gel forming ethylene oxide - propylene oxide block copolymer surfactant, such as Pluronic F-127 (trade mark);(c) a catalyst;(d) a blowing agent; and curing the resulting foam.