摘要:
Modified polytetrafluoroethylene unsintered powder of which has sintering-densification indexes P.sub.10, P.sub.25 and P.sub.50 of not larger than 0.2, which is suitable for producing a porous molding article.
摘要:
There is provided a polytetrafluoroethylene (PTFE) porous material which has improved adhesion and improved buckling resistance on bending without a tearing problem along a tubular axial direction. The porous material is composed of a polytetrafluoroethylene and a heat-meltable resin of which melting point is lower than that of the polytetrafluoroethylene, has fibril portions and node portions and characterized in that the fibril portions are mainly of the polytetrafluoroethylene, and the heat-meltable resin mainly constitutes the node portions and hardly constitutes the fibril portions. The porous material is produced by extruding powder for paste-extrusion, which comprises particles of the polytetrafluoroethylene produced by emulsion polymerization of tetrafluoroethylene and particles of the heat-meltable resin of which melting point is lower than that of the polytetrafluoroethylene, at a temperature which is not higher than the melting point of the heat-meltable resin optionally followed by rolling so that an unsintered material is obtained, stretching the unsintered material at a temperature which is not higher than the melting point of the heat-meltable resin, and then heat setting the stretched material at a temperature which is equal to or higher than the melting point of the polytetrafluoroethylene.
摘要:
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.
摘要:
A process for producing a multilayer polytetrafluoroethylene porous membrane comprising at least two layers having different average pore diameters is disclosed, the process comprising the steps of: filling the inside of a cylinder of an extruding mold distinctively with at least two kinds of polytetrafluoroethylene fine powders with each of which a liquid lubricant has been mixed; subsequently paste-extruding the powders to obtain a multilayer extrudate, which is then optionally rolled; and then stretching the extrudate or the rolled extrudate at least monoaxially after the liquid lubricant is removed therefrom or without removing the liquid lubricant.
摘要:
A tetrafluoroethylene polymer tube which is in a porous form composed of continuous pores and has heat-shrinkability in a radial direction or both radial direction and longitudinal direction of the tube, and a process for producing the same comprising applying pressure into inside of a tetrafluoroethylene polymer tube formed by paste extrusion molding a powder of the tetrafluoroethylene polymer and then sintered while heating the same to a temperature of not higher than the melting initiation temperature of the tetrafluoroethylene polymer to expand the tube to a radial direction only or both radial direction and longitudinal direction of the tube, and then cooling the tube in a pressurized state.
摘要:
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.
摘要:
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.
摘要:
A process for producing a multilayer polytetrafluoroethylene porous membrane is disclosed, which process comprises at least two layers having different average pore diameters, the process comprising the steps of: filling the inside of a cylinder of an extruding mold distinctively with at least two kinds of polytetrafluoroethylene fine powders with each of which a liquid lubricant has been mixed; paste-extruding the powders to obtain a multilayer extrudate, which is then optionally rolled; removing the liquid lubricant from the multilayer extrudate or the rolled multilayer extrudate to obtain an unsintered multilayer structure; subsequently heating the unsintered multilayer structure at a temperature not lower than the melting point of sintered polytetrafluoroethylene to obtain a semisintered multilayer structure; and then stretching the semisintered multilayer structure at least monoaxially. A semisintered polytetrafluoroethylene multilayer structure capable of being used as an intermediate material for the above process is also disclosed.
摘要:
A porous PTFE film having a thin thickness and good permeability is produced by coating an emulsion of polytetrafluoroethylene on a substrate surface, in particular, a porous polytetrafluoroethylene substrate which has not been heated at a melting point of unsintered polytetrafluoroethylene or higher, heating the coated substrate at a temperature not lower than a melting point of sintered polytetrafluoroethylene to semi-sinter polytetrafluoroethylene, optionally removing the semi-sintered polytetrafluoroethylene film from the substrate, and then stretching the semi-sintered film at least in one direction.