Abstract
It is well known that in the synthesis of Phenol Novolac Resins, molecular weight and molecular distribution are determined by the molar ratio of phenols and aldehydes. In order to prepare a type of Phenol Novolac Resins of low molecular weight with narrow molecular distribution, it is usual to lower the value of F/P (ratio of formaldehyde and phenol), by which excessive volume of phenols are to react with formaldehydes. But in this case, it is very much likely to see so much volume of unreacted phenols left.
In this paper, a new method of synthesis of naphthol-modified phenolic resins, which has settled such problem, is to be reported. By this new method of synthesis, under the existence of strong acid between the reflux reaction and the vacuum condensation reaction, lower molecular weight and narrower dispersion of molecular distribution were aimed to be accomplished through the maintenance of such condition as to keep water at the temperature of 150°C for longer than one hour. This Splitting-Recombining Reaction is generally taken place at such condition where naphthol and strong acid such as hydrochloric acid and PTS are in co-existence, although the Reaction would be rarely taken place at such condition where weak acid such as oxalic acid and zinc acetate were in existence. Further, it was found that this Reaction progresses under such condition where any other phenol is present so far as naphthol should be there. And it was also found that the degree of low molecular weight is larger at the higher range of F/P ratio.
