SPECIAL POLYESTER MULTIFILAMENT YARN AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To produce a special polyester multifilament yarn excellent in uneven shrinkability and process passableness by composing the multifilament yarn so as to make high shrinkable parts and low shrinkable parts alternately present in the fiber longitudinal direction without any constant stress extension region. SOLUTION: An undrawn polyester yarn is drawn at 10-150 deg.C temperature at a draw ratio within the range of (1 + elongation in a constant extension region×0.6) to (1 + elongation in the constant extension region×1.2) times and then heat-treated at <=130 deg.C temperature while being draw false twisted at 1.03-1.3 times draw ratio to produce a special polyester multifilament having highly shrinkable parts having 30-70% shrinkage percentage and low shrinkable parts having <=25% shrinkage percentage alternately present in >=2 sites per m in the fiber longitudinal direction and having <=70% average breaking elongation without a constant extension region. The resultant multifilament yarn is entangled and subjected to filament combining at 1.03-1.3 times draw ratio with another polyester multifilament yarn to afford a composite yarn.