Abstract:
An aqueous dispersion of granular PTFE particles and a melt-flowable fluorinated polymer powder particles is sprayed or cast to form a sheet. The sheet is then dried and the particles fused together to form an open network of fused interconnected particles that define a tortuous network of voids through the sheet. It has been found that when melt-flowable fluorinated polymers are present, the resulting fused sheets are stronger than when the fluorinated polymer is not present.
Abstract:
An oil supply device, usually a pad (32) or roller (30), for applying release oil to a fuser roll in a photocopying machine comprises an open-cell melamine foam reservoir (26) capable of operating at temperatures of 200 DEG C, having an oil-permeation control layer (14, 15) over the reservoir for controlling the supply of release oil. The oil permeation control layer may be a separate cover wick (20) or may be laminated by a layer (13) of adhesive to the reservoir (26). The device may be oil-fed or prefilled with oil. The oil permeation control layer is preferably a porous PTFE network formed by fusing granular-type PTFE particles.
Abstract:
An aqueous dispersion of granular PTFE particles and modified fine powder particles is sprayed or cast to form a sheet. The sheet is then dried and the particles fused together to form an open network of fused interconnected particles that define a tortuous network of voids through the sheet. It has been found that when the modified fine powder-type PTFE is present, the resulting fused sheets are stronger than when the modified PTFE is not present.
Abstract:
A flat cable comprises a series of parallel electrical conductors (1 to 6) each carrying a spiral-wound tape insulation layer (30). The conductors are held together by braiding formed of a plurality of tapes (10 to 22) or fibres interwoven between the conductors. The braiding is preferably of a thermoplastic material which may be heat bonded to the insulation in order to set the cable in a desired shape e.g. for a wiring loom. The insulation and braiding is preferably formed from a mixture of polytetrafluoroethylene (PTFE) and a copolymer of tetrafluoroethylene and perfluoro(propylvinylether).
Abstract:
The invention relates to a composite lining material for a garment or the like comprising a water resistant water-vapour-permeable flexible substrate (2) having a fabric (4) secured to a first side of the substrate (2). A second side of the substrate (2) is provided with an abrasion resisting discontinuous layer (10) made up of a plurality of discrete abrasion resisting polymeric dots (12). The dots (12) prevent abrasion of the flexible substrate (2) and, in use, form a lining for the material.
Abstract:
An aqueous dispersion of modified granular PTFE particles is sprayed or cast to form a sheet. The sheet is then dried and the modified granular particles fused together to form an open network of fused interconnected particles that define a tortuous network of voids through the sheet. It has been found that when the modified granular-type PTFE aqueous dispersions are employed, the resulting fused sheets are stronger than when the usual unmodified PTFE homopolymer of the granular-type is used.
Abstract:
A porous composite laminate material comprises a layer (4) of expanded polytetrafluoroethylene (PTFE) membrane, and a layer (2) of non-expanded porous PTFE attached thereto. The non-expanded porous PTFE layer may be a sintered porous PTFE produced by sintering granular-type PTFE particles to form a porous integral network of interconnected particles; and may be produced in situ by spray application onto the membrane followed by baking. Modifiers including unsintered fine powder PTFE, thermoplastic fluorinated organic polymer, a low molecular weight PTFE and mixtures thereof may be included. The expanded PTFE membrane can be in sheet form or in the form of expanded PTFE fibres woven into a fabric. The laminate may be used for oiling and cleaning high temperature fuser rolls in a photocopying machine, or as a filter.
Abstract:
An oil transfer component for transferring oil to a roll (2) in a fuser system of a copying machine, such as a plain paper copier or laser printer, is formed of contiguous layers (17a, 17b, 17c, etc.) of porous polytetrafluoroethylene sheet material. Typically, there are from three to twenty layers. The component may be formed by winding turns of a single length around a core (e.g. in the case of a roller (10)) or may be formed of separate sheets (32). The porous polytetrafluoroethylene may be formed from particles of granular-type polytetrafluoroethylene fused to form a porous integral network; or may be a porous expanded polytetrafluoroethylene. The oil transfer component is convenient to produce and has good oil delivery and toner wiping properties, and resists puddling of oil.
Abstract:
A method of purifying a liquid stream (A) such as a dying effluent stream, by adsorption of impurities in the stream onto a solid particulate adsorbent, such as activated carbon, comprises the steps: (a) placing the liquid (A) to be purified in a vessel (T) in contact with the particulate adsorbent for a period sufficient to ensure substantially complete adsorption of impurities from the liquid onto the adsorbent; (b) passing the liquid (A) and the suspended particulate adsorbent through a cross-flow filter (F) including a membrane (18) at a rate to produce turbulent flow over the membrane (18); (c) removing a stream of purified filtrate (16), free of particulate adsorbent from the liquid (A) through the membrane (18); and (d) returning the remaining liquid and suspended particulate adsorbent to the vessel (T).
Abstract:
A high strength porous composite material formed from PTFE comprises a fabric (4) formed of fibres produced from expanded PTFE, and a layer (2) of sintered porous PTFE formed thereon. The sintered porous PTFE is formed from granular type PTFE particules, which comprise at least a portion of presintered resin. The particles are fused to form a porous integral network. The material has good strength. It is useful for producing oil transfer components for use in photocopying machines.