Antistatic modification of synthetic fibers by blend‐spinning of polymers containing zwitterionic antistatic modifiers and their copolymers

New poly(oxyethylene) derivatives (S‐betaine) having a zwitterionic structure of ammoniumsulfonate were prepared by the reaction of oxirane (EO) adducts of stearylamine with sodium chloromethanesulfonate and examined as blending antistatic modifiers for poly(ethylene terephthalate) (PET) and polyamide 6 (PA6) fibers. The blend PET and PA6 fibers containing 2.0 wt.‐% of S‐betaine exhibited a decreased half‐life time of leakage of electrostatic charge (t 1/2 ) and a surface area resistivity (R s ) compared with those of the control PET and PA6 fibers. However, their antistatic properties were almost lost after repeated washings, because of the extraction of the agents. To increase the resistivity to washing, copolyester‐type modifiers comprising both S‐betaine and poly(ethylene glycol) were synthesized and incorporated into PET fibers. It was found that the antistatic properties of the blend PET fibers obtained can be retained even after dyeing and repeated washings.