Polyester granule for melt-shaping and process for the preparation thereof

Polyester granule for melt-shaping which is composed of a difficultly crystallizable copolyester having a minimum time for half-crystallization of at least 1 minute, and having surfaces resulting from cutting by a cutter,

• wherein:
• i. said polyester granule has an intrinsic viscosity of at least 0.55 (as measured in o-chlorophenol at 35.degree. C),
• ii. said polyester granule has on its surface an oriented portion having an N-value of at least 0.04, the N-value being calculated by equation (1):
• N = n .lambda./d (1)
• in which n is the number of interference fringes caused by double refraction counted upon the observation through a polarizing microscope using a light source of the wavelength .lambda. (microns), and
• d is the thickness (microns) of a sample prepared by slicing the granule to a predetermined thickness including a part of the cut surface of the granule and
• iii. the inside of the polyester granule other than the said surface portion has an N-value of not higher than 0.02,
• said cutting being performed under conditions which will control the surface temperature t (.degree. C) of the extrudate to satisfy equation (2):
• Tg + 30.degree. C .gtoreq. t >
• Tg - 15.degree. C (2)
• in which Tg is the second order transition temperature (.degree. C) of the extrudate.