| 摘要 |
PROBLEM TO BE SOLVED: To prevent the fusion of polyester pellets in the molding step and improve their blocking resistance by setting the band half-value width at a specified wavelength in the Raman spectrum at the surface and central part of a polyester pellet to a specified value or lower. SOLUTION: The half-value width of a band of 1,730 cm<-1> in the Raman spectrum at the surface of this polyester pellet is 22 cm<-1> or lower and that in the central part is 18 cm<-1> or lower. The pellet may be cylindrical, elliptically cylindrical, squarely cylindrical, platy, or spherical and has the size of one side of about 0.7-12 mm. The pellets are produced by extruding a molten polyester through a circular or elliptical die, cooling the resultant strand at the glass transition point or higher for a sufficient time, and cutting the solidified strand with a cutter or by cutting the extruded strand still in the semimolten state with a cutter and subjecting the resultant pellets to shearing treatment under machanical impact. |
