| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject compound suitable for the industrial production of a PBZ polymer having high polymerization degree, good color tone and excellent workability in molding. SOLUTION: The objective compound such as fine powder of cis-poly-p- phenylene benzobisoxazole is produced by pulverizing an aromatic dicarboxylic acid (e.g. terephthalic acid or naphthalenedicarboxylic acid) in a jet air stream to get a particle diameter distribution having a medium diameter of <=6μm and maximum particle diameter of <=20μm measured by a laser-analyzing particle size distribution analyzer and containing <=0.2wt.% of coarse particles having a diameter of >=32μm measured by wet sieving. The compound can be used as a raw material for a PBZ polymer of the formula I or the formula II [X is O, S or NH; Y is C or N; Z is a bivalent aromatic organic residue expressed by the formula III to the formula VI (R<1> and R<2> are each H, methyl, etc.)] (a homopolymer or copolymer containing heterocyclic group having the structure of the formula I or the formula II as a main constituent unit).
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