To produce a filter ensuring a small pressure drop, having satisfactory gas decomposing function, generating no contaminant from the filter itself and suitable for use as a filter for a clean room for producing a semiconductor, pharmaceuticals, food, etc., and to decompose low molecular siloxane with the filter.
Both sides of an unfired sheet of fluororesin such as polytetrafluoroethylene(PTFE) are coated with a dispersion of fluororesin contg. functional fine powder and plural such coated sheets are laminated, fired in one body and mechanically split by means of a brush with metallic needles to obtain short fluororesin fibers. These fibers are formed into a web by means of a carding machine, etc., the web is intertwisted with a jet of water and the resultant nonwoven fabric sheet is formed into the objective filter. The central layer 1 of each of the fibers is made, e.g. of PTFE resin and the surface layer 2, 2' is made, e.g. of PTFE resin mixed with photocatalytic anatase type TiO2 powder.
SATO KENJI
DOMOTO TADANORI
