| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polymer reduced in the tendency toward gelation and fish eye formation by crystallizing a poly(m-xylyleneadipamide) having a specified relative viscosity and a specified difference between the concentrations of two types of specified terminal groups, adjusting the moisture concentration, and heating the polymer to the melting point or below in vacuo after it reaches a specified degree of crystallinity. SOLUTION: A poly(m-xylyleneadipamide) obtained by the melt polycondensation of m- xylylenediamine and adipic acid and satisfying the relationships: 1.83 <= relative viscosity <=2.28 (in 96% sulfuric acid at 25 deg.C) and 8μeq/g <= difference between concentrations of two types of terminal groups ([COOH]-[NH2]) <=82μeq/g is adjusted to a moisture concentration of at least 0.2 wt.% in a heater. The polymer is crystallized by heating to 60-160 deg.C in an atmosphere having an oxygen concentration of at most 5 vol.% under conditions in which the highest temperature of the heating surface of the heater is 120-230 deg.C. After the its degree of crystallinity reaches 15%, the heater is evacuated to a degree of vacuum of at most 500 Torr, and the polymer is heated to a temperature lower than the melting point by at least 15 deg.C to form a polymer satisfying the relationships: 2.30 <= relative viscosity <=4.20 and 8μeq/g <= difference between concentrations of two types of terminal groups <=82μeq/g.
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