| 摘要 |
PROBLEM TO BE SOLVED: To precrystallize isophthalic acid copolyester chips while preventing them from being fused and from lowering in handleability and intrinsic viscosity by drying them in the presence of fed moisture under specified conditions. SOLUTION: Isophthalic acid copolyester chips are fed from a chip inlet 3 into a drier containing an atmosphere heated to a temperature below the Tg measured by DSC before being crystallized by means of a heater 1, and moisture is fed thereinto from a feed inlet 4. They are agitated with impellers 5 and 6 driven in the counter directions by a motor M and heated to a temperature determined by formula I (wherein M is the rate of the copolymerized isophthalic acid and is in the range: 10mol%<=M35 mol%; T( deg.C) is the temperature of the atmosphere contained in the drier; and Tg ( deg.C) is the glass transition temperature) over a period of time determined by formula II (wherein (t) is the crystallization treatment time and is in the range: t>=0.25). The dried chips are discharged from an outlet 8 to obtain a copolyester giving a thermogram in which at least one Tm' (a multiple melting peak temperature ( deg.C) which appears on the side lower than Tm) when measured by DSC, the total of the respectiveΔHm' (the heat absorption of Tm', Cal/g) is 0.1-8 times as high asΔHm (the heat absorption (Cal/g) at Tm) and having a degree of crystallinity of 25-50%.
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