Wenderoth, Lind & Ponack
Vinylidene fluoride resin split yarn, process for production thereof and filter comprising the same
 A vinylidene fluoride resin having an inherent viscosity of 0.8 to 1.4 dl/g in dimethylformamide is melt-extruded and cooled and solidified under draft-stretching to form a film having a birefringence of 25.times.10.sup.-3 or larger. The film is heat-treated at 80.degree.-120.degree. C. and split into a split yarn. The split yarn has a Young's modulus even higher than that of the polypropylene split yarn and, when provided with a surface charge above the glass transition temperature, retains the charge semi-permanently. The charged split yarn is particularly suitable for forming a gas filter. 
Kureha Kagaku Kogyo Kabushiki Kaisha
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Toshiya Yoshikichi Naohiro
Mizuno Teramoto Murayama