POLYCONDENSATION OF NOVOLACS CONTAINING DOMINATELY ORTHO-ORTHO-METHYLENE LINKAGES

In an early stage of the polycondensation of phenol/formaldehyde (Ph/F ) systems catalyzed by bivalent metal acetates (Me(2+)(ac)(2)), 2-hydr oxy-benzylalcohol (2-OH-BA) formation was selective in the weak acidic medium and only in the presence of the catalyst. The concentration ch ange in 2-OH-BA and its hemiformal (HF) was followed by GPC as a funct ion of the pH value of the system and the catalyst concentration and w as found to be independent of the type of metal used in the catalyst b ut dependent on the pH value of the medium and on the catalyst concent ration. An extremely high catalyst concentration does not cause furthe r increase in the overall rate of 2-OH-BA formation. It was proved by H-1 NMR that at higher conversion and in the presence of Me(2+)(ac)(2) catalyst, the o-o'-Ar-CH2-Ar isomers are dominating over o, p' and p, p' ones. Novolacs with overwhelming o-diphenylmethane structures are thermally stable up to 400 degrees C and can be crosslinked without he xamethylenetetramine (HEXA).