Polybenzoxazole(s) prepn. for use in coatings and reinforced plastics - by condensing a bis-ortho-aminophenol with a di:carboxylic acid (OE 15.12.77)

摘要

Bis-o-aminophenols of formula (I): (where Y is OH, Z is NH2) and (I) (where Y is NH2, Z is OH) is a molar ratio of 1:9-9:1, are condensed with a dicarboxylic acid or a reactive deriv. to form a polybenzoxazole contg. corresp. groupings (II): (where X is O, S, SO, SO2, CO or CR1R2, R2 are same or different H or alkyl). The reactive deriv. of the diacid is pref. a diacid is pref. a diester, esp. a diphenyl ester, or a dihalide esp. a dichloride or bromide. (I) (where Y is OH, Z is NH2) and (I) (Y is NH2, Z is OH) are pref. used in a molar ratio of 2:3-3:2. Reaction can be performed in a melt or by heating in polyphosphoric acid at 120-350 degrees C, when using free acid or an ester. Using a dihalide, reaction is pref. at -20 to 150 degrees C, esp. -20 degrees to 50 degrees C, and the prod. is cyclised at 200-400 degrees C, opt. after impregnating onto a reinforcing material. Reactive terminal gps. are pref. deactivated using 0.5-2.0 mole % of a blocking agent, e.g. benzoyl chloride, o-aminophenol, etc. The polymers have good solubility organic solvents, and good thermal and radiation stability.