Polyester different shrinkage combined filament yarn and process for its production

Abstract

A polyester combined filament yarn composed of a self-extending polyester multifilament yarn A and a heat-shrinkable polyester multifilament yarn B, wherein the polyester multifilament yarn A comprises a core portion and a plurality of fin portions protruding in a radial fashion from the core portion along the lengthwise direction of the core portion, and the following conditions (a) to (c) arc simultaneously satisfied. 1/20 ≦S B /S A ≦⅓  (a) 0.6 ≦L B /D A ≦3.0  (b) W B /D A ≦¼  (c) (where S A represents the cross-sectional area of the core portion, D A represents the diameter of the core portion when the cross-section is a circle and the circumscribed circle diameter when it is not a circle, and S B , L B and W B represent the cross-sectional area, maximum length and maximum width, respectively, of the fin portions.)

1 . A polyester combined filament yarn composed of a self-extending polyester multifilament yarn A and a heat-shrinkable polyester multifilament yarn B, the polyester combined filament yarn being characterized in that the polyester multifilament yarn A comprises a core portion and a plurality of fin portions protruding in a radial fashion from the core portion along the lengthwise direction of the core portion, and in that the following conditions (a) to (c) are simultaneously satisfied. 
        1/20 ≦S   B   /S   A ≦⅓  (a) 0.6 ≦L   B   /D   A ≦3.0  (b)   W   B   /D   A ≦¼  (c) (where S A  represents the cross-sectional area of the core portion, D A  represents the diameter of the core portion when the cross-section is a circle and the circumscribed circle diameter when it is not a circle, and S B , L B  and W B  represent the cross-sectional area, maximum length and maximum width, respectively, of the fin portions.)    
   
   
       2 . A process for production of a polyester combined filament yarn according to  claim 1 , characterized in that heat-shrinkable polyester multifilament yarn B′ is paralleled with multifilament yarn A′ which becomes the self-extending polyester multifilament yarn A when subjected to relaxation heat treatment, and after supplying them to an interlacing nozzle with an overfeed for interlacing, heat relaxation treatment is carried out to impart a self-extending property to the polyester multifilament yarn A′, prior to a second relaxation heat treatment with a non-contact heater.  
   
   
       3 . A process for production of a polyester combined filament yarn according to  claim 2 , wherein the relaxation heat treatment for imparting the self-extending property is carried out on a heated roll at 100-130° C.  
   
   
       4 . A process for production of a polyester combined filament yarn according to  claim 2 , wherein the polyester multifilament yarn A′ and polyester multifilament yarn B′ are paralleled and supplied to the interlacing nozzle at an overfeed rate of 1.0-1.5%.  
   
   
       5 . A process for production of a polyester combined filament yarn according to  claim 4 , wherein interlacing is introduced at 50-90/m in the interlacing nozzle.  
   
   
       6 . A process for production of a polyester co-lined filament yarn according to  claim 2 , wherein the second relaxation heat treatment is carried out at 210-240° C. at an overfeed rate of 1.5-2.5%.