PURPOSE: To produce a filter film having excellent strength and water permeability by impregnating the doping liquid in which a blank material for film is dissolved into a sintered molding of metal, glass, ceramics, etc. and filming the same.
CONSTITUTION: A meltable inorg. material of glass, metal, ceramics, etc. having 1W100μ grain sizes is sintered to form a filter element of 1W25mm thickness. Said element is dipped in doping liquid in which a suitable blank material for film is dissolved to impregnate the liquid in the molding; thereafter, the doping liquid is evaporated for a required time. The filter element is further allowed to gel in cold water and is subjected to a heat treatment according to need. The filter element produced by evaporating the doping liquid from both surfaces thereof permits filtration from both directions. In other words, when the filter element loses its filtration efficiency, it permits starting of filtration from the opposite direction and since the element is backwashed by such filtration, the filtration operation is continued with good efficiency. Even a material which can not be made to a film by the conventional process due to its insufficient strength can be formed to a film by the process of this invention.
MATSUDA YOSHITO
ABE KEIJI
TOMITA SHIGERU
| JPS52137466A | 1977-11-16 |