Rapidly crystallising block copolymers - contg. block segments of low glass transition temp. e.g. polyethylene glycol!(s)

摘要

Prepn. of copolyester is improved by forming a codiol-free polyethylene terephthalate resin with an intrinsic viscosity of >=0.2 dl/g, homogenising this in the melt with the codiol and the block segment polymer, and subjecting the solidified melt to solid phase post-condensation. The prods. are moulding materials with exceptionally good crystallisation properties. They can be injection moulded at mould temps. of 80-120 degrees C, esp. 90 degrees C whilst retaining their rapid crystallisation characteristics, so that moulds can e.g. by water cooled. The prods. can be moulded using considerably shorter cycle times than with conventional polyethyleneterephthalate injection moulding materials.