Abstract: To provide a PTFE composite fiber having remarkably improved thermal bonding property, PTFE cotton-like materials which can be used for producing a non-woven fabric by thermal bonding method, processes for production thereof, a process for producing a split yarn, a process for producing a monofilament and a process for producing a multifilament having loop and/or branched structure.A thermofusing resin layer is provided on the surface of the PTFE fiber. After lamination of the PTFE film and the thermofusing resin film, uniaxial stretching is carried out at a temperature between the melting points of the respective films.

Abstract: The present invention provides cotton-like mixed materials containing the PTFE fibers and other fibers uniformly and being excellent in intermingling property, non-woven fabrics obtained from the cotton-like mixed materials, and a process for preparation thereof.The split yarn having a network structure and obtained by splitting the uniaxially stretched PTFE film with the needle blade rolls in the stretched direction and the other continuous filament are fed simultaneously to the needle blade rolls rotating at high speed.

Abstract: An object is to provide a polytetrafluoroethylene (PTFE) porous composite film which has substantially no defect portion.There is provided the PTFE porous composite film by stretching a composite along its width direction which composite is composed of at least two overlapped films longitudinally stretched at a temperature not higher than a melting point of a sintered PTFE material, each film being obtained by paste-extruding and semi-sintering thereafter a PTFE produced by emulsion polymerization.

Abstract: To provide a PTFE composite fiber having remarkably improved thermal bonding property, PTFE cotton-like materials which can be used for producing a non-woven fabric by thermal bonding method, processes for production thereof, a process for producing a split yarn, a process for producing a monofilament and a process for producing a multifilament having loop and/or branched structure.A thermofusing resin layer is provided on the surface of the PTFE fiber. After lamination of the PTFE film and the thermofusing resin film, uniaxial stretching is carried out at a temperature between the melting points of the respective films.

Abstract: A porous polytetrafluoroethylene film which is excellent as an air filter used in clean rooms in a semiconductor industry, which is suitable for the collection of microparticles floating in a gas such as air and exhibits a low pressure drop is provided. The film has an average pore size of from 0.2 to 0.4 .mu.m and exhibits a pressure drop of from 20 to 50 mmH.sub.2 O when air is passed through it at a flow rate of 5.3 cm/sec. The film is prepared by stretching biaxially unsintered polytetrafluoroethylene at specific temperatures.

Abstract: Cotton-like polytetrafluoroethylene materials are obtained by opening a uniaxially stretched article of molded polytetrafluoroethylene by a mechanical force. Those cotton-like materials comprise the 5 to 150 mm long fibers having branches and crimps and non-uniform section. The cotton-like materials are excellent in intermingling property and can be easily made into non-woven fabrics.

Abstract: A filter apparatus that is compact and that provides a large filtration area includes filter elements each constructed in cylindrical form by spirally winding a filter medium. Such medium includes a porous membrane of a polytetrafluoroethylene having a pore diameter of 0.1 to 5 .mu.m and low pressure loss and one or a pair of sheets composed of fibers made of a thermally melting synthetic resin. One end of the cylindrical filter element is connected to a respective through hole in a rigid support plate, and the opposite end is blocked.