Conductive composite fiber and method for producing same

Abstract

Provided is an electrically conductive conjugate fiber formed by conjugating an electrically conductive layer (A) including 60 to 80% by weight of a thermoplastic resin and 20 to 40% by weight of electrically conductive particles and a protective layer (B) including 50 to 95% by weight of polyethylene terephthalate and 5 to 50% by weight of polyethylene-2,6-naphthalate, wherein the fiber has a degree of elongation (DE) of 100 to 350%. This provides an electrically conductive conjugate fiber which exhibits a small change with time in physical properties such as a degree of elongation or boiling water shrinkage during its transportation or storage, while having a certain degree of elongation.

1 . An electrically conductive conjugate fiber formed by conjugating an electrically conductive layer (A) comprising 60 to 80% by weight of a thermoplastic resin and 20 to 40% by weight of electrically conductive particles and a protective layer (B) comprising 50 to 95% by weight of polyethylene terephthalate and 5 to 50% by weight of polyethylene-2,6-naphthalate, wherein the fiber has a degree of elongation (DE) of 100 to 350%. 
     
     
         2 . The electrically conductive conjugate fiber according to  claim 1 , wherein the thermoplastic resin constituting the electrically conductive layer (A) is polybutylene terephthalate or polyamide. 
     
     
         3 . The electrically conductive conjugate fiber according to  claim 1 , wherein the fiber has a weight ratio (A/B) of the electrically conductive layer (A) to the protective layer (B) of from 5/95 to 50/50. 
     
     
         4 . The electrically conductive conjugate fiber according to  claim 1 , wherein the fiber has a boiling water shrinkage (Wsr) of 20 to 60%. 
     
     
         5 . The electrically conductive conjugate fiber according to  claim 1 , wherein when the fiber is stored under a condition of 60° C. and 80% RH, the degree of elongation (DE 60 ) at a time 60 days after the spinning is not greater than 1.3 times the degree of elongation (DE 1 ) at a time one day after the spinning. 
     
     
         6 . The electrically conductive conjugate fiber according to  claim 1 , wherein when the fiber is stored under a condition of 60° C. and 80% RH, the boiling water shrinkage (Wsr 60 ) at a time 60 days after the spinning is not less than 0.3 times the boiling water shrinkage (Wsr 1 ) at a time one day after the spinning. 
     
     
         7 . The electrically conductive conjugate fiber according to  claim 1 , wherein when the fiber is stored under a condition of 60° C. and 80% RH, the boiling water shrinkage (Wsr 60 ) at a time 60 days after the spinning is 10% or more. 
     
     
         8 . A carpet in which a fiber obtained by stretching the electrically conductive conjugate fiber according to  claim 1  is used. 
     
     
         9 . A method for producing an electrically conductive conjugate fiber comprising conjugately spinning a resin composition (a) comprising 60 to 80% by weight of a thermoplastic resin and 20 to 40% by weight of electrically conductive particles and a resin composition (b) comprising 50 to 95% by weight of polyethylene terephthalate and 5 to 50% by weight of polyethylene-2,6-naphthalate, wherein the molten resin composition (a) and the molten resin composition (b) are merged together, melt-discharged through a conjugate spinneret, and then wound at a rate of 1500 to 3000 m/min. 
     
     
         10 . The method for producing an electrically conductive conjugate fiber according to  claim 9 , wherein the following (1) through (5) are performed in this order, and the (2) and (3) are performed before a discharged thread comes into contact with a roller or a guide for the first time:
 (1) merging the molten resin composition (a) and the molten resin composition (b) together and conjugately melt-discharging them through a conjugate spinneret,   (2) cooling the discharged molten resin composition temporarily to a temperature lower than a glass transition point,   (3) subsequently transferring it through a heating device to subject it to heat-stretching treatment,   (4) thereafter providing oil to it, and   (5) winding it at a rate of 1500 to 3000 m/min.