PURPOSE: The titled fibers, consisting of polyethylene terephthalate and polybutylene terephthalate, having specific values of specified physical properties, e.g. fiber strength, and capable of giving stable steps and nonwoven fabrics having improved heat resistance, strength and feeling, etc.
CONSTITUTION: Mixed polyester based binder fiber, consisting of (A) 40W80wt% polyethylene terephthalate and (B) 60W20wt% polybutylene terephthalate, having ≥1.5g/denier fiber strength, ≤250% fiber elongation, ≤5% shrinkage in hot air at 140W180°C, capable of increasing the birefringence thereof by ≥20×10-3 by heat treatment in the hot air, and having ≥100×10-3 birefringence after the increase and ≤25% yarn shrinkage when a fiber bundle having about 1000 yarn denier and 1m length is passed through and calendered with a pair of flat rolls set under 10kg/cm linear pressure and at 140W180°C at 5m/min speed.
OKADA HIROMASA
NOGUCHI YOSHISHIGE
AKIYAMA SHIYOUJI
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