PURPOSE: To obtain an electret filter capable of enhancing collection efficiency and of preventing collection performance from being especially lowered even when the electret filter adsorbs tabacco smoke by using resin whose wet contact angle for pure water is regulated to the specified value or above as resin for the electret filter.
CONSTITUTION: Resin whose wet contact angle for pure water is regulated to ≥95° preferably about 100-110° is used as resin for an electret filter. For example, poly(4-methyl-1-pentene), polytetrafluoroethylene,' fluoroethylene- propylene copolymer, perfluoroalkoxy-fluororesin or the like and the modified substances of these resins due to unsaturated carboxylic acid such as maleic anhydride, unsaturated epoxy compound and organosilicon compound and organofluorine compound, etc., of these resins are shown as such resin. Further even resin whose wet contact angle for pure water is regulated to the angle smaller than 95° can be used as resin for the filter when silicone oil is added at 0.05-5wt.% and the wet contact angle is regulated to ≥95°.
YOSHISHIBA TSUNEO
SHINAGAWA YOSHIO
