Abstract: High performance silicone rubber windshield wiper blades are provided as a result of molding a tintable platinum group metal catalyzed silicone compositions having an intrinsic viscosity of less than 1.3. Improved lubricity with respect to windshield wiper glass is achieved by a molding procedure which effects a transfer such as a migration, or diffusion of release agent, for example polytetrafluoroethylene, into the surface of the silicone rubber windshield wiper blade.

Abstract: A continuously operating press for pressing a web of material together has a press zone at an input side a calibration zone at an output side. This press may be used in the formation of particle board by applying heat and pressure to press the web of material together to form the particle board. Preferably, the press has a lower press platen and an upper press platen that are pressed together to form the particle board. Both the lower press platen and the upper press platen preferably have a PTFE composite pressure pad. This composite pressure pad may have a layer of virgin PTFE and a layer of filled PTFE. The layer of filled PTFE is preferably partially compressed at a pressure of about 14.7 psi. After which, the layer of filled PTFE is preferably compression molded with the layer of virgin PTFE to form a composite. This composite may also be sintered and coined.

Abstract: Methods of compression molding powdered polytetrafluoroethylene resins to produce composite articles of manufacture having at least two distinct layers of two types of PTFE resin are disclosed. A first layer of resin, preferably including a filler, is placed in a compression mold and partially compressed at a relatively low pressure. A second layer of resin, preferably virgin resin, is then added to the mold and both layers are simultaneously fully compressed. After compression, the resulting composite preform is preferably sintered and coined to create a finished PTFE material or product. In a preferred embodiment, the partial compression step is performed at pressures of less than 500 psi. It has been found that modified PTFE resins provide improved resistance to cold flow and also provide better binding between filled and unfilled (virgin) layers and thus are used in certain preferred embodiments.

Abstract: A platen cover feed system includes a frame supporting a pair of spools. A belt is connected at each end to the spools and can be fed from one spool to the other or vice versa. The spools can be mounted on supports located at the four top corners of the frame, and the rear supports can be adjusted to various heights. The system may include clamps associated with the spools. The clamps can be tightened or loosened manually in order to either fix the belt in place or feed it forward or backward. Thus, the belt can be fed a varying distance in either direction. The belt is generally made of, or coated with, Teflon or a similar non-sticking material.

Abstract: An apparatus for producing expanded thermoplastic microspheres, including a belt conveyor (A) having an endless belt (1) for conveying microspheres. A device (B) for infrared (IR) heating, including a plurality of IR lamps (4) is located above the belt (1). A dosing device (C) for the dried unexpanded microspheres is located at one end of the belt conveyor and in conjunction with the belt (1). A collecting device (D) for expanded microspheres is located at the other end of the belt conveyor and in conjunction with the belt (1).

Abstract: According to the present invention, the copolymers of ethylene vinyl alcohol are extruded using extrusion equipment coated with a fluoropolymer. This method improves the processability, alleviates/slows down die buildup, improves the extrudate quality by reducing die lines on surfaces of the extruded product.

Abstract: A concrete block molding apparatus and component molding parts coated with a flame spray refractory material and binder composition. The coatings can be smoothed to provide a finished surface for the blocks as by polishing, pressure on the coated surface or preferably by a coating of a thermoset resin as a binder. A preferred thermoset resin includes polytetrafluoroethylene (PTFE) in the coating to improve slipperiness. The parts have a greatly increased life cycle and the apparatus has a much longer cycle time between changes of the parts.

Abstract: Continuous process and apparatus form products from thermoplastic materials between top and bottom mold carriages. A flexible silicone rubber mold on a fiber belt continuously moves around each carriage frame. A surface of desired shape on one rubber mold mates with the desired shape of an opposed rubber mold forming a continuously moving mold channel into which is fed hot thermoplastic material at moldable temperature. After discharging the molded plastic product from the moving mold channel, localized surface heat in the molds resulting from contact with hot plastic is removed from the belt molds by air blown onto mold surfaces. Each carriage frame includes a back-up plate coated with low friction coefficient material over which slides a continuously moving belt mold. These slippery plates have numerous air-bearing holes feeding high pressure air between them and the respective moving fiber belt for reducing friction and wear.

Abstract: A method and an apparatus for treating contaminated plastics waste, comprising densifying contaminated plastics waste by causing the waste to pass through a heating zone to produce molten contaminated plastics, and causing the molten contaminated plastics to flow continuously out of the heating zone under the influence of gravity.

Abstract: A process for the manufacture of a thin-walled tube of fluorinated resin, particularly polytetrafluoroethylene, in which a ribbon of fluorinated resin obtained by lubricated extrusion and calendaring, is wound into a tube on a mandrel, the winding of the ribbon being performed in a plurality of layers, and the thus-wound ribbon on the mandrel being brought to a temperature above the sintering temperature of the fluorinated resin for sufficient time to produce sintering. The wound tube and the mandrel are cooled; while on the mandrel the thin-walled tube is rolled to elongate the tube, to reduce the thickness of the tube, and to increase the inside diameter of the tube; and then the mandrel within the tube is extracted.

Abstract: A method of making a flanged pipe length includes flaring a metal pipe by rotating a grooved tool about the inside of the pipe and introducing a plastic tubular sleeve into the pipe. The tubular sleeve is subsequently heated and forced against the flanged portion of the metal pipe whereby the plastic material assumes a shape complementing the projections formed by the grooved tool.

Abstract: A method of making a lightweight hose assembly including a step of extruding the inner liner. A nonmetallic material is then braided about the exterior of the liner. The inner liner and braided layer are then passed through a reservoir containing a solution of the fluorocarbon polymer. The solvent is then removed, leaving a fluorocarbon polymer coating dispersed throughout the braided layer.

Abstract: A process for preparing an improved expanded porous polytetrafluorethylene product having a higher density and improved cold flow properties and prepared from a paste formed from a polytetrafluoroethylene resin and a lubricant. The method includes extruding the paste through an extrusion die at a reduction ratio of less than 100, calendering the extrudate, removing the lubricant, and heating the extrudate to a temperature greater than the crystalline melting point of polytetrafluoroethylene but generally below the temperature at which thermal decomposition becomes appreciable while concurrently expanding the extrudate to at least twice its original length.

Abstract: A method for welding together filled sintered polytetrafluoroethylene components. The ends of the components to be welded are carefully tapered to form reverse mated surfaces and then assembled in position to be welded. The actual welding step is carried out under heat and pressure followed by cooling under pressure. The process is particularly useful in the fabrication of very large gaskets or other very large planar objects.

Abstract: A flat stock strip of thermoplastic material is passed through a heating station in contact with the edges of longitudinally oriented heated knife blades to heat soften the stock strip along narrow longitudinal lines to define localized fold lines for the stock strip. The strip is fed sequentially through a prebending device and a chilled forming die to set the reformed strip at the fold lines. Preferably the knife blades and any strip contact surfaces of the prebending device and the chilled forming die are PTFE covered to eliminate scratching of the thermoplastic stock strip material during heating, reforming and cooling.

Abstract: A transfer film comprising a base film and a releasant layer, an ink layer and an adhesive layer laminated on the base film in this order is inserted into a cavity of an injection mold, and injection molding material is injected into the cavity. After the molded article is removed from the mold, the base film is peeled off and the ink layer is transferred to the surface of the molded article. The injection mold has a coring pin for forming an opening in the molded article and the contact surface of the coring pin to be brought into contact with the adhesive layer of the transfer film has poor adhesion to the adhesive layer so that the bond strength between the contact surface of the coring pin and the adhesive layer is lower than those between the ink layer and the releasant layer and between the releasant layer and the base film.

Abstract: A method for producing a linear low density polyethylene (LLDPE) film by slot-die extrusion from an extrudate having an inherent draw resonance tendency whereby draw resonance is eliminated in the production of film at high speeds. Film of commercially uniform gauge thickness is obtained having significantly improved strength over films formed by conventional slot-die extrusion of LLDPE.

Abstract: A tube closure apparatus for sealing the open end of a plastic tube, such as the tip of a pipette, comprising a sealing element constructed of a fluoroplastic material and a heating element for controllably heating the sealing element to a temperature greater than the melting temperature of the plastic tube. Unlike a metal sealing element, the fluoroplastic sealing element resists any tendency of the molten plastic tube to stick to the sealing element. Accordingly, a uniform sealing bead can be efficiently and reproducibly formed at the open end of the plastic tube. The heating element can be heated by resistance, induction, conduction or other suitable means.

Abstract: Tetrafluoroethylene polymer tubes are ram extruded. Desirable quality tubes are obtained by positioning an insert between ram and mandrel to maintain the ram and mandrel concentric.

Abstract: An extruder process for blending carbon fiber and tetrafluoroethylene copolymer resins, and laminates from the product of the process.

Abstract: A conveyor 4 driven by a motor 5 feeds thermoplastic waste material 2, such as the trimmed-off edges of extruded plastics sheets, to a compression chamber 8 at the inlet of a heating box 10 of an extruder 11. The conveyor operates intermittently in synchronism with the movement of a plunger 40 operated by a hydraulic cylinder 42 which compresses the waste material to the level of a restraining member 50 controlled by a pneumatic cylinder 54. The member 50 comes into operation as the plunger 40 reaches the bottom of its stroke and holds the plastics material in a compressed condition while the plunger 40 rises again, further material 2 is fed to the chamber 8 and the cycle is repeated, the member 50 being withdrawn shortly before the plunger 40 reaches the bottom of its stroke.

Abstract: In a method for producing a plastic foam of a desired expanded dimension which is constituted by extruding a melt of a thermoplastic synthetic resin containing a blowing agent through a die of an extruder and passing the extrudate through a shaping device located outwardly of the extruder and secured to the discharge end of the extruder while expanding and solidifying the molten mass so that it fills the shaping device; the improvement wherein at least a part of that area of the inside surface of the shaping device with which the expanded resin makes contact is formed of a plate of a fluorocarbon resin, said plate being secured to the inside surface of the shaping device by fitting portions, said fitting portions having a sufficient space for absorbing an increase in the volume of the fluorocarbon resin plate at the temperature of extrusion molding; and an apparatus for use in the above described process.

Abstract: A profiling die for use in processing tubular material where finish is a priority, such as for use in a catheter, the die being composed of a body of heat conductive material having a through passageway composed of a first bore extending from one face and a second coaxial bore extending from an opposite face, the second bore being larger than the first bore and there being an intermediate section between the bores which is tapered from the diameter of the second bore to the diameter of the first bore and wherein the tapered intermediate section and the first bore are aligned by an integral annular insert of Teflon material and preferably a keeper is provided to maintain the insert within the die.

Abstract: In making films or molded articles from polyamide, polyimide, or polyamide-imide resins, the problem of stripping or release is successfully solved by applying a noble metal layer on the surface of a film-casting belt or plate or a casting mold to be in contact with the resins.