| 摘要 |
Phenolic resoles (I) are prepd. by reacting phenol, or mixt. of phenols, with aq. HCHO in presence of Ba (OH)2, neutralising with dil. H2SO4, then removing water from the strongly turbid, BaSO4-contg. mixt. until a clear soln. is formed. Pref. water is removed by vacuum distn., partic. at 50-65 deg.C., esp. to resin solids content at least 65%. Molar ratio phenol(s): HCHO is 1:1.1-3.3, partic. 1:1.4-2.6. |
