| 摘要 |
PURPOSE:To obtain a separator having uniform swelling degrees in both width and longitudinal directions in electrolyte by subjecting a non-stretched with polymer base film to agraft polymerization with acrylic acid, etc., after exposure to a radiation. CONSTITUTION:A non-stretched polyethylene film is put in a polyethylene bag and then exposed to a 20Mrad electron ray-irradiation at a 2MeV acceleration voltage and a 1mA acceleration current at room temperature in nitrogen gas. Then, the film so treated is put in a glass ampoule and degassed under the reduced pressure of 10<-4>mmHg. Then, a reaction liquid obtained by adding 0.25% a Mohl's salt to a 50% acrylic acid aqueous solution is injected into the glass ampole to cause reaction to take place 10hr in a 25 deg.C constant-temperature tank. After the reaction, the grafted film thus obtained is washed with water to sufficiently extract unreacted monomer and homopolymer present and then dried to obtain a separator. |
