On the basis of the conventional method for preparing a phenolic resin, a cyclization reaction of primary amines, phenols and aldehydes is carried out to obtain a benzoxazine intermediate. Under the heating or catalyst conditions, a ring-opening reaction of benzoxazine is carried out to produce a novel thermosetting resin having a net structure, wherein the condensate has a better heat resistance, fire resistance and electricity property.
Among the raw materials for preparing benzoxazine intermediate, the aldehydes used therein include formalin, paraformaldehyde; the amines include aromatic amines, alkyl primary amines, alicyclic primary amines; the phenols are primarily single phenol compounds, bisphenol compounds, trisphenol compounds, multifunctional phenols, phenolic resins, para hydroxystyrene, polymers or copolymers thereof. However, there is no report that the phenol as shown in Formula (2) is used as the phenol source for preparing a benzoxazine intermediate.
