method for preparation of scale of emissions of one.

摘要

1491730 Foamed phenol-formaldehyde resins SOC CHIMIQUE DES CHARBONNAGES 27 Dec 1974 [28 Dec 1973] 55969/74 Headings C3C and C3R A foamed phenol-formaldehyde resin is made by reacting phenol with formaldehyde in the presence of a base, concentrating the resulting resol to form a product having a dry extract content (measured as defined) of at least 85% and a viscosity at 20‹ C. of above 1,000 poise, mixing the product at 50-72‹ C. with a blowing agent and a low activity acid catalyst (i.e. an acid hardening catalyst which is insufficiently active to cause hardening of the resin at 50-72‹ C., and blowing and hardening the mixture at 80-120‹ C. In the examples phenol and formaldehyde were reacted in the presence of sodium hydroxide and the mixture was neutralized with hydrochloric acid and the resin either decanted or passed through an ion exchange column, and then concentrated under reduced pressure after optional addition of polyethoxylated castor oil, the product is then mixed with hexane or heptane and phosphonic acid or the acid sulphate of triethylene glycol, and optionally triethylene glycol or a silicone surfactant and the mixture is east in a mould; in Example 6 a foam was produced continuously and fed on to a support which was passed through an oven.