The present invention relates to a method of manufacturing a filter element for use in a dust collector such as those used in, for example, a factory for separating particles contained in gas kept at a temperature from room temperature up to 160.degree. C., for collecting powder products or environmental safety or used to remove dust contained in exhaust gas of a drier, a boiler or an incinerator.
A filter bag made by sewing a filter cloth or a filter element such as sintered plastic material having intercommunicating porosity has been used for collecting dust particles produced in a factory for product collection or dust removal. As the porous plastic filter element having been produced by sintering synthetic resin particles, a self-supporting member produced by sintering polyethylene particles, polypropylene particles or a mixture of these particles is disclosed in Japanese Patent Gazette 5934/1989 and the same member coated with adhesive containing tetrafluoroethylene is disclosed in Japanese Patent Application Laid Open No. 502381/1986.
On the other hand, for collection of dust contained in exhaust gas of a drier, a boiler or an incinerator, a dust collector or an electric dust collector using a filter element has been used widely, a heat durable filter cloth of glass fiber or heat resistive synthetic resin fiber or a sintered ceramic filter when gas temperature exceeds 300.degree. C. being incorporated in the filter element.
It has been known, however, that, although the sintered porous synthetic resin material filter bag or filter element is effective at around room temperature, it is easily deformed and thereby rendered unsuitable for normal use at a temperature above about 70.degree. C.
The filter bag incorporating glass fiber or heat resistive synthetic resin fiber cloth has been used to separate particles from gas at a temperature of 160.degree. C. or lower. However, since texture thereof is usually rough, there may be leakage of dust therethrough or, when a felt cloth made of such fiber is used, the felt cloth may be clogged gradually with dust particles layered thereon, causing flow resistance of air therethrough to be increased which means that a higher power is required for a blower. Further, in the case of filter bag, pressurized air is supplied intermittently in an opposite direction to dust containing gas flow to blow away particles accumulated on the filter surface. This causes friction between an insert for the bag for maintaining the shape thereof and the filter cloth to occur, frequently damaging the latter.
When, in order to separate particles from gas at 160.degree. C. or lower, a dust collector using the sintered ceramic filter member or an electric dust collector is used, the cost thereof becomes high, as the sintered ceramic filter member or the eletric dust collector itself is expensive.