Abstract: Tetrafluoroethylene polymer tubes are ram extruded. Desirable quality tubes are obtained by controlling the back pressure on the mandrel as the ram forces polymer to be fabricated into the barrel of the extruder.

Abstract: An air/oxygen electrode substrate for use as a cathode in alkali metal halide electrolysis processes is formed by compressing a prefused mixture of carbon black and a hydrophobic polymer such as polytetrafluoroethylene under high pressures and at a temperature in excess of the sintering temperature of the polymer and below its decomposition temperature. Optionally, the electrode may be formed having a core comprised of a metal mesh which acts to better distribute the applied voltage and to reinforce the electrode. Further, a sheet of hydrophobic backing material such as TEFLON fabric may be incorporated into the compressed mixture to increase the hydrophobic properties of the cathode. Electrocatalysts may then be deposited on the surface of the electrode substrate to produce an oxygen electrode having significant voltage advantage over mild steel cathodes in alkali-halide electrolysis cells.

Abstract: A hopper-feeder (10) especially suited for, but not limited to, continuously feeding self adhering powders to a subsequent processing step is disclosed. In particular, the apparatus includes a first hopper (12), an intermediate passageway (16), a second hopper (18) and a feed guide (20). A wiper (32), a bottle brush auger (34) and an associated auger cleaning rod (36) expedite powder flow. Shear blades (40), disposed within the second hopper (18), further break up any undesirable particles before exiting the apparatus (10).

Abstract: Tetrafluoroethylene polymer is downwardly extruded employing variable counterweight to provide tube of improved physical properties.

Abstract: A flexible tube and a method of manufacturing same and provided. The flexible tube comprises a tubular body of a crystalline polymer material having a porous microstructure including a number of micro-nodes which are coupled together by fibrils. A synthetic resin material having gas tightness and stretchability is filled into the pores of the porous microstructure.

Abstract: A composition suitable for manufacturing into wear-resistant and chemically-inert articles, the composition being a mixture of 74 to 84% polytetrafluoroethylene, 7-17% graphite fibers, and 4-14% fluorinated graphite.

Abstract: A wear-resistant and chemically-inert article made from a sintered mixture of polytetrafluoroethylene, graphite fibers, and fluorinated graphite.

Abstract: Low shrinkage, mechanically strong, acid stable, carbon fiber reinforced poly(vinylidene fluoride) resin compositions are prepared by extrusion blending carbon fibers, which have been precoated with poly(vinylidene fluoride), with a poly(vinylidene fluoride) resin.

Abstract: A method of continuously manufacturing strips which include at least one thin porous conductive layer, said strips being intended in particular to form electrodes for fuel cells, in which method one stage in the manufacture of said layer includes passing powdered material to form it between the rolls of a calender. The method, said material is prepared by mixing an aqueous dispersion of carbon powder, which is possibly coated with a catalyst, with an emulsion of binder; precipitating the binder on the powder; drying and dry crushing the precipitate then wetting the powder while crushing is continued, with a liquid intended to prevent the grains from adhering to the rolls of the calender while lubricating said grains material thus obtained, being free from any pore-forming product, is calendered without using any support.

Abstract: Transfer molding of polypropylene, polyvinylidene fluoride, FEP fluorocarbon resin or PFA fluorocarbon resin to produce a lining for a 6" tee pipe fitting is accomplished isothermally by applying pressure of the order of 200 psi to the material while the material, the charge holding chamber and the tee mold are secured in a fixture in an oven. Transfer is performed at a stabilized resin temperature of the order of 375.degree. F. for polypropylene, 450.degree. F. for polyvinylidene fluoride, and 640.degree. F. for FEP and PFA resins over a relatively long time interval. Pressure is removed, the mold assembly is transferred to a press outside the oven, pressure of the order of 700 psi is reapplied to the material, and the mold is force cooled progressively from a remote point back toward the gate which is located in the fitting opposite the stack section thereof.

Abstract: A novel plastic composition, and process of its preparation and application, are disclosed having particular utility in providing metal castings or the like with bubble-free, highly inert, plastic linings or coatings. The predominant portion of the novel composition comprises a perfluoroalkoxy side chain modified fluorocarbon polymer but also includes, in effective minor amount, metallic tin and preferably also additional oxidation or degradation stabilizers.

Abstract: Oxidation of stranded copper wire during high temperature coating with non-melt-fabricable tetrafluoroethylene polymer is substantially prevented by subjecting the wire to a nonoxidizing atmosphere during heating immediately prior to and during coating.

Abstract: Microporous membrane materials suitable for use in electrolytic cells, such as cells for the electrolysis of brine to produce chlorine, are formed from a mixture of polytetrafluoroethylene, a particulate pore forming material and an organic fluorinated lubricant. Such materials are preferably formed into a sheet, which is rolled to a desired thickness, sintered and subjected to leaching out of the pore forming material.

Abstract: A composite cylindrical mold for making rubber covered rolls comprises an outer rigid tube and an inner hollow cylindrical sleeve, with the space between the tube and the sleeve being filled with a cured elastomer. In preparing the mold, a heat shrinkable polytetrafluoroethylene tube etched on the outer surface is disposed around a rigid mandrel and heat shrunk thereon. The mandrel and sleeve are then inserted into the rigid tube in concentric relation. Curable rubber is then injected under pressure between the tube and the sleeve and the rubber is cured, causing the inner surface of the sleeve to conform exactly to the surface of the mandrel. The mandrel is then removed, and the inner surface of the sleeve is used as a molding surface for rubber covered rolls.

Abstract: In the isostatic molding of linings, an improved flange-to-flange seal is obtained when a generally rectangular ring is employed in a generally rectangular groove.

Abstract: Porous film materials composed of polytetrafluoroethylene having an asymmetric structure are produced by stretching the film using a pair of revolving rolls which are heated to a temperature lower than the melting point of the film. Stretching is produced by revolving the two rolls at different speeds which also tends to produce a compressive force in the thickness of the film. The rolls are heated to different temperatures to produce a temperature difference of preferably 50.degree. C. or more. The combination of the compressive force and the temperature gradient in the thickness of the film is believed to produce the asymmetric structure in the resulting porous film materials which are characterized by a fiber structure in the surface which is different from that in the back.

Abstract: A porous thermoplastic sheet is formed by adding a material to a polymer latex to passivate the aqueous phase of the latex. An additional material of a preselected particle size, corresponding to the desired pore size of the final product is then added. The latex composition is gelled and is then formed into a sheet. The sheet is dried and cured or sintered and the solubles are extracted therefrom with a solvent. A preferred polymer latex is PTFE.

Abstract: Polytetrafluoroethylene resin tubes having small pore size and high porosity are produced by a process which includes stretching the tubes by drawing using a metal die and a metal plug. By using the die and plug, the stress necessary for stretching is converted to a compressive force in the thickness direction of the tube. This compressive force is an essential factor in producing the microporous structure of the tubes. In addition, when stretching is performed by drawing, a ratio of thickness to inside diameter of the tube of 0.07 or less can be easily achieved.

Abstract: The present invention provides a method of making an improved catalyst useful for hydrogenation of organic compounds and in other reactions. The method comprises mixing a porous particulate refractory support material with a hydrophobic polymeric binder to form an essentially homogeneous mixture and then catalyzing this mixture by introducing into the pores of the mixture a salt of a metal of the eighth group of the Periodic Table in a non-polar solvent in which the salt is ionizable. Further in accordance with the method, the salt is reduced to the catalytic metal within the pores of the mixture, specifically within the pores of the support material, by contacting with a selected reducing agent, for example, hydrazine or sodium bis (2-methoxyethoxy) aluminum hydride, preferably in solution. A porous structure is formed from the mixture either before or after the catalysis. Preferably, the structure is sintered as a final step.

Abstract: A porous polytetrafluoroethylene tubing, useful as artificial internal organs or industrial filtering materials for, for example reverse osmosis, ultrafilteration, etc., having a microporous fibrous structure in which the fibrous structure is composed of fibers and nodes connected with each other and the microporous fibrous structure differs between the outer surface portions of the tubing and the inner surface portions of the tubing, and a process for producing the porous resin tubing comprising heating a tubing made of an unsintered polytetrafluoroethylene under conditions in which the tube is stretched at least in the longitudinal direction of the tubing and such that the outer surface of the tubing is heated above about 327.degree. C. and the inner surface of the tubing is heated to a temperature below the temperature of the outer surface.

Abstract: A process for making dry carbon/polytetrafluoroethylene floc material, particularly useful in the manufacture of fuel cell electrodes, comprises of the steps of floccing a co-suspension of carbon particles and polytetrafluoroethylene particles, filtering excess liquids from the co-suspension, molding pellet shapes from the remaining wet floc solids without using significant pressure during the molding, drying the wet floc pellet shapes within the mold at temperatures no greater than about 150.degree. F., and removing the dry pellets from the mold.

Abstract: A liquid junction for a reference electrode and a method of forming the same, in which a hydrophobic polymer support material has a liquid junction layer or portion of material therein comprised of a hydrophobic polymer in mixture with either an inactive particulate substance, an electro-chemically inactive salt, or a combination of said inactive particulate substance and said electro-chemically inactive salt. The support member and the liquid junction therein are compression formed in a mold and are heat-treated following the final compression treatment.

Abstract: This application relates to a paste extrusion process using a ram type extruder wherein at least one, preferably both, of the die and mandrel of the extruder are rotated, in opposite directions when both are rotated. In preferred embodiments, the material being extruded is polytetrafluoroethylene, the mandrel has a smooth surface and the end portion of the die is heated.

Abstract: In a process for aftertreating thermally presintered polymers of tetrafluoroethylene the optionally comminuted powders are subjected, at temperatures below +80.degree. C., to the action of a gas jet mill. Preferred starting materials are tetrafluoroethylene polymers containing a small proportion of a modifying monomer. By the aftertreatment the bulk density and the flow index of the powders are considerably improved without a noticeable disintegration taking place. The aftertreated powders are used in the first place for the manufacture of shaped articles in extrusion devices with automatic feeding means.

Abstract: A composition of material suitable for in vivo implantation to provide a wear surface which composition includes carbon fibers, perfluorocarbon fibers, fluorinated carbon fibers, fluorinated carbon particles, fluorinated hydrocarbon fibers, fluorinated hydrocarbon particles, polytetrafluoroethylene fibers or combinations thereof and polytetrafluoroethylene resin alone or with a high molecular weight polyethylene all of which composition is processed to align a substantial portion of the fibers with the wear surface. The preferred method of preparing such composition of material includes the steps of mixing, filtering, compressing, rolling, sintering and drying.

Abstract: A plant nourishment delivery device having a variable flux capability and comprising a water-permeable membrane having a conditioned flux capability in the range of about 0.005 to 10 cubic centimeters per minute per square centimeter at an applied hydrostatic pressure of about 1 atmosphere, and an exaltation of said conditioned flux capability in the range of about 30% to 10,000%.

Abstract: A novel diaphragm suitable for use in electrolytic cells and a novel method of making the diaphragms are provided. The diaphragm according to the invention is characterized in that a reinforcing element is associated with a microporous membrane by integrating it with the anode face of the said membrane. The novel diaphragms are particularly suitable for use in the electrolysis of alkali chlorides.

Abstract: Polytetrafluoroethylene tubes are prepared by isostatic molding of polytetrafluoroethylene powder over a cylindrical mandral at a temperature below about 19.degree. C. The compacted preform and mandrel are then warmed to a temperature above about 19.degree. C. and the preform removed from the mandrel. Sticking of the preform to the mandrel is avoided.

Abstract: A method for forming a microporous sheet of fluorocarbon polymer (e.g., polytetrafluoroethylene). An aqueous dispersion of polytetrafluoroethylene which includes a dissolved water-soluble, crystallizable metallic organic salt, preferably sodium benzoate, is formed into a sheet. Water is evaporated from an exposed surface of the sheet to grow crystals of the organic salt dispersed throughout the sheet. Then, the sheet is sintered. After cooling, the salt crystals are leached from the sheet by dissolution in water to leave a porous structure suitable for such uses as a filtration membrane or as a separation barrier in batteries or electrolytic cells.

Abstract: A waterproof article for use in, for example, protective clothing. The article prevents liquid water from penetrating through to undergarments while at the same time permitting moisture vapor such as perspiration to pass out through the article. The article is thus both breathable and waterproof. The article is layered: a microporous hydrophobic outer layer which permits the passage of moisture vapor but resists penetration by liquid water at pressures up to about 345 Kn/m.sup.2 ; a hyrophilic inner layer permitting the transfer of moisture vapor but preventing surface tension lowering agents such as those contained in perspiration and/or body oils from reaching the hydrophobic layer.

Abstract: Articles of manufacture having good green strength and low modulii of elasticity, and comprising a matrix of fibrillated polytetrafluoroethylene interconnecting and entrapping a high volume, at least about 85%, of a particulate and preferably a sinterable material selected from the group consisting of metals, intermetallic compounds, ceramics, salts, plastics, and combinations thereof. Said articles are formed by mechanically working a substantially dry mixture of a fibrillable polytetrafluoroethylene polymer and a high volume, at least about 85%, of the particulate material. Metal, ceramic and plastic articles prepared by heat treating, such as sintering, the articles of manufacture are also disclosed.The heat treated products are useful, inter alia, as structural elements and electronic components.

Abstract: Polytetrafluoroethylene resin tubes having small pore size and high porosity are produced by a process which includes stretching the tubes by drawing using a metal die and a metal plug. By using the die and plug, the stress necessary for stretching is converted to a compressive force in the thickness direction of the tube. This compressive force is an essential factor in producing the microporous structure of the tubes. In addition, when stretching is performed by drawing, a ratio of thickness to inside diameter of the tube of 0.07 or less can be easily achieved.

Abstract: A method for molding a cover on a metal core by preforming cover segments and molding the latter to size with the core interposed therebetween. When molded, the preformed segments are gradually deformed and uniformly compacted to a high density particularly in regions in direct contact with the wall surfaces of the mold, with no inclusion of cracks, pinholes or other structural defects therein. The product molded in this manner exhibits a very high corrosion-resisting characteristic with no machining operation conventionally required thereon, particularly when molded of tetrafluoroethylene resin powder.

Abstract: Microporous membrane materials suitable for electrolytic cell utilization are formed from the blend of particulate polytetrafluoroethylene, a dry pore forming particulate material, and an organic lubricant. The materials are milled and formed into a sheet, which is rolled to the desired thickness, sintered, and subjected to leaching of the pore forming materials.

Abstract: A polytetrafluoroethylene composite sheet having a tensile strength of at least one megapascal and comprising particulate material distributed in a matrix of interentangled polytetrafluoroethylene fibrils. The composite sheet is prepared by blending the particulate material with polytetrafluoroethylene aqueous dispersion in the presence of sufficient lubricant water to exceed the absorptive capacity of the solids yet maintain a putty-like consistency, subjecting the putty-like mass to intensive mixing at a temperature between 50.degree. C. and 100.degree. C. to cause initial fibrillation of the polytetrafluoroethylene particles, biaxially calendering the putty-like mass to cause additional fibrillation of the polytetrafluoroethylene particles while maintaining the same water content and drying the resultant sheet.

Abstract: A sheet material, principally comprised of a polymer such as polytetrafluoroethylene, having characteristics which permit its use in a fuel cell electrode is formed from co-agglomerates of the polymer and a pore former. In a fuel cell electrode application, the polymer-pore former agglomerates are themselves caused to co-agglomerate with a catalyst, the resulting co-agglomerates are formed into a layer and the pore former is leached from the layer so as to produce a structure having gas channels only in the polymer portions thereof. Agglomeration of the pore former and polymer particles is permitted through first imparting a positive charge to the pore former particles. The gas permeable catalyst layer will be bonded to a support plate to define a fuel cell electrode.

Abstract: The fibrillated surface layer of an unsintered extruded mass of a polytetrafluoroethylene is broken by mechanical or electrical force to facilitate evaporation of the lubricant whereby a molded article which is free from defects such as cracks and blisters is obtained upon sintering.

Abstract: Finely ground polytetrafluoroethylene molding powder with or without a filler is subjected to high speed agitation in the presence of a medium consisting essentially of water and a hydrophobic organic liquid at a ratio of 0.5 to 1 liter per 1 Kg of the resin to agglomerate it. Hydrophobic organic liquids mean organic liquid which dissolve less than 15 wt. % in water at the temperature of agglomeration.The volumetric ratio of the organic liquid to water is in a range of 2 to 1/2.The agglomerated product having narrow particle size distribution and high bulk density and free flowing property can be obtained by the agitation for short time.

Abstract: An improved process for making a gas diffusion electrode which comprises heating of the mixed electrode material prior to forming the electrode. Because of the stickiness or self adhesion characteristics of the electrode mixture, the invention includes special transport apparatus having a fluidized bed that uniformly disperses the sticky electrode material onto a conveyor belt for forming the electrode without subsequent heating.

Abstract: A tetrafluoroethylene polymer comprising primary particles having core and shell portions, the core portion comprising tetrafluoroethylene polymerised in the presence of a perfluoroalkyl or alkoxy trifluoro-ethylene comonomer, particularly hexafluoropropylene, and shell portion consisting of tetrafluoroethylene homopolymer, or a copolymer of tetrafluoroethylene in which the comonomer concentration is less than half that in the core portion.

Abstract: A method of preparing a porous sheet product which comprises the step of introducing a spinning liquid comprising an organic fibre forming polymeric material into an electric field whereby fibres are drawn from the liquid to an electrode and collecting the fibres so produced upon the electrode. PTFE and other fluorinated polymer mats produced by the electrostatic process are useful as electrolytic cell diaphragms, battery separators etc.

Abstract: A composite article having a first layer formed of one material and a second layer of a second material, said layers being mechanically bonded together by mating projections extending from one layer into cavities of said other layer, said cavities having inwardly diverging surfaces for receiving said projections to preclude axial separation of said layers. The disclosure also includes a process for the manufacture of such articles.

Abstract: The disclosure is of a method of making air filter fabrics from non-woven, thermoplastic, synthetic polymeric resin, staple textile fibers and of the fabrics so made. The method comprises providing a non-woven web of the fibers, coating the fibers with a fiber stabilizing agent, pressing the fibers together so as to rupture the film at cross-over points and fusing the fibers together at the sites of the ruptured film. The product filter fabrics are characterized by controlled high permeability, strength, wear resistance, dimensional stability, lint free surfaces and advantageous particle release properties.

Abstract: The present invention provides porous polytetrafluoroethylene ("PTFE") products having fine pores and high porosity, the pore diameter being less than about 1,500A, generally ranging from about 100A to 1,000A. The process for the manufacture of these products comprises: (a) shaping of a lubricated PTFE mixture, by extrusion and/or rolling; (b) a first stretching of the shaped mass while in an unsintered state; (c) free sintering of the stretched mass at a temperature above 327.degree. C; and (d) a second stretching of the sintered mass. These porous PTFE products are suitable for use as gas separators, diaphragms, filters, and other applications.

Abstract: A membrane of a porous unexpanded polytetrafluoroethylene (PTFE), such as that made by the matrix technique disclosed in U.S. Pat. No. 3,497,256, issued Feb. 24, 1970, in sheet form is sandwiched between metal foil layers that are stiff enough to take a dead set crimp; the three layer composite is passed through corrugating gears; the corrugated composite is indexed between two grooved plates under moderate pressure and the composite is heated while between the plates to heat set the plastic membrane; then the metal foil layers are removed after cooling.

Abstract: An unsintered tube of extruded ptfe resin is heated above its melting temperature of 327.degree. C, a positive pressure is established within the tube relative to the external pressure thereon to radially expand it, and the pressure is maintained until the tube is cooled below its melting point and set. Such a tube demonstrates superior strength and crack resistance when it is thereafter radially contracted around a core member by reheating, and its longitudinal shrinkage is minimized.

Abstract: Method of molding granular polytetrafluoroethylene powder which comprises compressing the powder in a mold at a pressure of between about 10 and 50 bars to form a preform and subjecting the preform to isostatic molding at a pressure of between about 100 and 1000 bars.

Abstract: A compliant roller for use in a xerographic fusing apparatus is made by placing a rigid gudgeoned roller core in a mold assembly with a preshrunk outer sleeve positioned about the interior surface of the mold and by forcing an elastomeric siloxane, e.g., silicone rubber, between the core and the sleeve. The sleeve is comprised of a material which contains tetrafluoroethylene and/or hexafluoropropylene copolymers. The ends of the roller are sealed with an epoxy resin and a forming fixture to form an oil tight and airtight seal.

Abstract: This invention provides a tetrafluoroethylene polymer in a porous form which has an amorphous content exceeding about 5% and which has a micro-structure characterized by nodes interconnected by fibrils. The material has high porosity and high strength. It can be used to produce all kinds of shaped articles such as films, tubes, rods, and continuous filaments. Laminations can be employed and impregnation and bonding can readily be used to produce a large variety of articles. Compressed articles of very high strength can also be produced from these porous forms.

Abstract: Pipes with walls thicker than 4 mm are made by paste extrusion of PTFE powder in the presence of a lubricant. The extrusion is carried out at a reduction ratio below 20:1. The PTFE powder is a mixture of 80 to 99% by weight of coagulated dispersion grade PTFE and 20 to 1% by weight of PTFE having a median particle size less than 50 micrometers. The mixture is preferably a co-coagulation of the two forms of PTFE.