Study on Twisting Conditions of Polyester Filament Yarns and Craping

Since high-value added fabrics of polyester hard twist filament yarn which are main products in our prefecture has been woven by water jet looms, demand for polyester hard twist yarn is increasing rapidly. As a result, the dependence on the double twister which is superior in productivity to Italian twister is inceasing more and more.On the other hand, the craping of double twister on which the feeling of hard twist yarn fabrics depends is different from Italian twister's.A study has been made to investigate : (1) What is the extent of the difference between craping produced by the double twister and that by the Italian twister?(2) Interrelations among the condition of twisting, the condition of the fabric relaxation, craping and other physical properties of the twist yarn.Through these investigations, we could get the following basic data : (1) When the revolution speed of the spindle increases, the twisting tension also increases, the number of ribs tends to increase and fine craping tends to appear.(2) At 12 000 rpm, craping appear scarecely difference if the setting condition is altered.(3) From the viewpoint of the effect of the scouring teperature, the higher temperature, the more number of ribs and the finer rib. The most craping appears at 70→130°C/60 min.(4) Double twister can easily produce stronger craping than Italian twister.