Abstract: Toughened thermoplastics are prepared by mechanically dewatering a water-moist elastomer component A containing up to 50% by weight of residual water and mixing the resulting dewatered elastomer component A' with a thermoplastic polymer B in a mixing unit, by a process in which the elastomer component A is fed to a twin-screw extruder which has corotating, in each case triple-flight, screws and essentially includes, in the transport direction,one unheated metering section in which the elastomer component A is fed to the extruder by a metering means,at least one squeeze section which serves for dewatering and contains at least one retarding element and in each case at least one associated dewatering orifice,at least one section in which the thermoplastic polymer B is introduced as a melt into the extruder,at least one section provided with mixing, kneading or other plasticating elements or combinations of these elements,at least one devolatilization section which is provided with at least one devolatilization

Abstract: Thermal insulating device with an open celled polyurethane foam core, evacuated and refilled with an insulating gas.

Abstract: A method for making upholstered articles comprising a foam core, an integrally attached cover assembly, and an integrally attached scrim is provided. The method includes the step of positioning an air-impermeable cover assembly over a mold cavity of a molding apparatus, applying a vacuum to the fabric through a plurality of apertures in the walls defining the mold cavity to cause the fabric to conform to the shape of the mold cavity, depositing a foam precursor into the mold cavity, positioning an air-impermeable scrim over the foam, and allowing the foam precursor to expand to form the article. The method allows upholstered articles having an integrally attached cover assembly to be manufactured using a pour-in-place process which does not utilize abherents, while still preventing bonding of the foam core to the lid and/or other surfaces of the molding apparatus.

Abstract: A method for producing composite, structural plastic parts in traditional foundry molds, including sand, permanent, die-cast, wax and investment molds. Short fiber length fibers reinforcing low viscosity thermoset resins, and in particular resole phenolics, provides a pourable low bulk density polymer compound with minimal externally applied thermal requirements during molding and post cure when required. Foundries can consider metal parts replacement with this new method. It permits foundries to actually produce composite, structural plastic parts with superior mechanical and thermal properties. This permits them to provide plastic products on a competitive basis with the compression and injection molders.

Abstract: Non-planar integral evacuated insulation panels and a method for making these by providing grooves in the filler material prior to enveloping said filler and forming by evacuating, which method allows to make evacuated insulation panels of specific non-planar shapes depending on the depth and shape of the grooves.

Abstract: A process for preparing fiber reinforced composite structures utilizing resin transfer molding techniques with vacuum and a resin which is capable of being cured with a peroxide catalyst or photocuring or a combination thereof.

Abstract: A method for manufacturing a resin-impregnated endless belt structure is carried out on an apparatus having an outer cylinder having an inner cylindrical surface coaxial with a smaller radius cylindrical mandrel. An endless base structure for the endless belt structure is disposed within the outer cylinder on the inner cylindrical surface. The cylindrical mandrel, having an inwardly curved nose, is then inserted into the outer cylinder forming a nip of converging geometry between the nose and the inner cylindrical surface. Polymeric resin material is dispensed continuously into the nip while the cylindrical mandrel is gradually moved completely into the outer cylinder. The nose forces the polymeric resin material into the endless base structure, and air bubbles out, while forcing the endless base structure against the inner cylindrical surface.

Abstract: Compositions, methods, and systems for manufacturing articles, particularly containers and packaging materials, having a highly inorganically filled matrix. Suitable inorganically filled mixtures are prepared by mixing together an organic polymer binder, water, one or more aggregate materials, fibers, and optional admixtures in the correct proportions in order to form an article which has the desired performance criteria. The inorganically filled mixtures are molded to fashion a portion of the mixture into a form stable shape for the desired article. Once the article has obtained form stability, the article is removed from the mold and allowed to harden to gain strength. The articles may have properties substantially similar to articles presently made from traditional materials like paper, paperboard, polystyrene, plastic, or metal. They have especial utility in the mass production of containers, particularly food and beverage containers.

Abstract: The invention provides a polyolefin drug packaging material characterized in that the content, in the polyolefin, of substances containing 12 to 26 carbon atoms is not more than 150 ppm. The packaging material of the invention is useful because the risk of its reacting with and adversely affecting the drug packaged therewith is minimum.

Abstract: A process for recycling a thermoplastic resin covered with a thermosetting-resin paint film includes the steps of decomposing the paint film by bringing the thermoplastic resin covered with the paint film into contact with a paint-film-decomposing agent in a molten state, and removing decomposed products, resulting from the paint film and the paint-film-decomposing agent, and the residual paint-film-decomposing agent by degassification to prepare a recycled resin. The paint-film-decomposing agent can be primary amines and/or secondary amines having a boiling point of 250.degree. C. or less, or being decomposed at 250.degree. C. or less, or can be tertiary amines and/or quaternary amines having a boiling point of 250.degree. C. or less, or being decomposed at 250.degree. C. or less to which water and/or alcohols is added.

Abstract: Method and apparatus for manufacturing void free products using vacuum transfer molding. The method comprises evacuating gas from a preheated resin mixture in an injection accumulator assembly before injection into a mold. The apparatus includes a fixed upper platen assembly supporting an injection accumulator assembly having appended thereto a gas exhausting means and a feed material holding canister on its upper surface and an upper match mold portion on its lower surface. The movable lower platen assembly supports a lower match mold portion on its upper surface and is supported by a plurality of hydraulic cylinders of a bottom plate assembly. The platen assemblies include a sandwich of a press plate, an insulating fiber board and an internally heated platen.

Abstract: An automated method and apparatus is provided to mold and cure soft contact lenses. At a first station, front curve mold halves are partially filled with a polymerizable monomer. At a second station, a surfactant coating may be applied to a flange on the front curve mold half to provide subsequent preferential adhesion of any excess hydrogel to a back curve mold half at the time the mold halves are separated. At a third station, the mold halves are assembled under vacuum, and clamped to displace any excess hydrogel from the mold cavity. This clamping step firmly seats the back curve mold half, severs any excess monomer from the monomer in the cavity, defines the lens edge, and seals the cavity in a vacuum. Following assembly of the mold halves, the assembly is transported to a precure station and reclamped, and the monomer is precured with actinic radiation, such as UV, to partially cure the monomer to a gel like consistency.

Abstract: An extrusion method and apparatus for removing volatile contents from solid state resin materials is described. A cascade-type extruding device is used having first and second extruders. A top end portion of the first extruder 10 is directly connected to a rear side portion of a cylinder of the second extruder 100. Volatile contents of a melted resin, which is melted when the solid state resin material is supplied to the first extruder, are removed in a volatile content removing vacuum unit provided on an upstream side of the connection between the first and second extruders. The melted resin is then extruded from a nozzle provided at a top end portion of the second extruder. The volatile content removing vacuum region of the volatile content removing vacuum unit 140 extends over a first region, which is under the control of the first extruder, and a second region, which is under the control of the second extruder.

Abstract: A process is for producing machine components from highly corrosion and water-resistant cast mineral, especially for the production of monolithically cast pump housings or parts in which the binder is first mixed with the filler in a positive mixer and the finished mixture is poured into a mould and hardened. In order to obtain a dense and non-porous casting which needs no further machining, a heat-curing synthetic resin-curing agent system is used as the binder. The binder and filler are mixed in a heatable, evacuated positive mixer at a temperature of over 20.degree. C. and a pressure of under 80 mbar. The casting take place in a preheated mould as a rising casting. The cast mineral in the mould is first cured at a temperature of over 60.degree. C. and the cured casting is removed from the mould, cleaned, measured and if necessary post machined. Finally the casting is cured in an annealing furnace at over 120.degree. C.

Abstract: Compositions, methods, and systems for manufacturing articles, particularly containers and packaging materials, having a particle packed, highly inorganically filled, cellular matrix are disclosed. Suitable inorganically filled mixtures are prepared by mixing together a starch-based binder, a solvent, inorganic aggregates, and optimal admixtures, e.g., fibers, mold-releasing agents, rheology-modifying agents, plasticizers, coating materials, and dispersants, in the correct proportions to form an article which has the desired performance criteria. The inorganically filled mixtures have a predetermined viscosity and are heated between molds at an elevated temperature and pressure to produce form-stable articles having a desired shape and a selectively controlled cellular, structure matrix. The molded articles may be placed in a high humidity chamber to obtain the necessary flexibility for their intended use.

Abstract: A press-forming apparatus is disclosed in which a preform such as green sheets, for example, is charged into a cavity in a pressure container, the cavity is covered with a lid member, and the green sheets are pressed by a pressure medium while the green sheets are heated by heating means, whereby the green sheets are press-formed into an integral laminated product. The pressure force should preferably be fluctuated during the pressing operation.

Abstract: Methods and systems for readily and economically manufacturing hydraulically settable articles, particularly containers, from microstructurally engineered hydraulically settable mixtures wherein the mixture is extruded into a sheet that is feed through a plurality of sets of rollers so as to form the sheet into the desired thickness. The sheet is then pressed between a male die of a desired shape and a female die having a substantially complimentary configuration of the male die shape to immediately fashion a portion of the sheet into a form stable shape for the desired article. To assist in imparting form stability, the dies can be heated or cooled. Once the article has obtained form stability, the article is removed from the dies and dried under heated air to gain strength. The article can then be cut from the sheet and receive printing or a coating, if desired, prior to packaging, shipping, and use.

Abstract: The tubular extrusion of a thermoplastic nonderivatized cellulose solution about a mandrel and through a long air gap in excess of 304 mm is facilitated by use of a mandrel which is extensible from the extrusion die. On extrusion start-up, the mandrel extends a short length from the die. For steady-state operation, the mandrel is extended its full length from the die. Also disclosed is a mandrel structure to facilitate the introduction of a nonsolvent liquid into the interior of the extruded tube at a high location on start-up of extrusion and at a lower location during steady-state operation. The mandrel also includes a sizing portion having circumferential grooves which gather gas bubbles that may evolve at the interface between the extruded tube and the sizing portion. Vertical channels in the sizing portion connect these grooves and provide the passage of gas bubbles into a volume below the mandrel.

Abstract: In a vent arrangement comprising a heating cylinder 1 containing therein a screw and provided with a vent hole 3 and a reduced pressure exhaust path 4 provided with a vacuum pump and connected to the vent hole 3 for draining volatile fractions of a material to be molded from the heating cylinder by reducing the pressure in the vent hole by means of the vacuum pump, said volatile fractions are removed by arranging in the exhaust path a filter unit 7 filled with a granular filtering material 8. The material to be molded is used for the filtering material 8. According to the above construction, it can be achieved to efficiently remove volatile matters by using the molded material as the filtering material of the filter unit arranged in the reduced pressure exhaust path of a vent arrangement.

Abstract: A styrenic resin is prepared by a method which comprises extruding a styrenic polymer powder having a syndiotactic configuration at a molding temperature of from the melting point of the polymer to 400.degree. C. at an extrusion rate meeting the equation Q/(D.times.H.times.V)=2.0.times.10.sup.4 to 6.0.times.10.sup.5, by the use of an extruder provided with one or more vents having an internal pressure of 0 to 760 Torr, wherein Q is an extrusion rate (kg/hr), D is a screw diameter (m), H is a screw groove depth (m), and V is a screw peripheral speed (m/sec); a residual volatile component, such as a monomer in the styrenic polymer powder having the syndiotactic configuration, can economically and efficiently be decreased at the time of extrusion, whereby a molding material having a good shape and containing a reduced amount of the residual volatile component can efficiently be prepared to prevent the emission of an objectionable odor at the time of the extrusion or molding.

Abstract: An automated transfer/injection process is defined that includes a charge forming unit, a shuttle unit, and a molding unit. The charge is formed from one or more slabs of reinforcing fibers and a resinous material. Once formed, the charge is preheated in the charge shuttle unit and is delivered to the molding unit, whereupon the preheated charges are forced by the pressure of a movable platform under vacuum into a mold cavity for polymerization. The fibers within the slabs are randomly oriented in parallel horizontal planes such that they are always parallel to the direction of initial flow into the cavity.

Abstract: A transparent mold system (TMS) allows rapid and economical production of thermoset fiber reinforced plastics (FRP) and other thermoset resin parts by heating with visible light energy without using an autoclave, photosensitive resins, or ultraviolet (U.V.) sensitive chemical curing agents. Molding times are accelerated to minutes instead of hours, and the molds are made of transparent plastics materials that can be economically produced by injection, casting, vacuum or pressure forming to replace metal molds and laid-up FRP molds.

Abstract: A method of and apparatus for molding hollow items using the resin transfer molding technique in such a manner that the resin is more uniformly distributed about and along the molding region of the mold. This is accomplished by installing oppositely spaced grooves in the mold and injecting resin directly into these grooves. Upon such injection, the resin travels along and fills the groove (by taking the path of least resistance) before such resin is squeezed or forced out a minute gap that exists between the molding surfaces and into the molding region of the mold. As such resin is being forcibly injected into the cloths in the mold, a vent permits any air displaced from the cloths by the resin to be released. Such resin injection and mold venting occurs until such time that no more air is vented and instead 100% resin is being discharged from the mold. Upon this occurrence, further resin injection is curtailed and the resin previously injected is allowed to harden and cure.

Abstract: For the manufacture of breast prostheses from a shell-shaped body made from an addition-vulcanising two-component silicone rubber mass, which body is enclosed in a plastic sheet sheathing said body, a filler of fairly low density composed of hollow spheres or microspheres is added to the two-component silicone rubber mass. The mixture is filled into a sheath of plastic sheet and is cured in a mould under the effect of heat. To obtain the most uniform distribution possible of the filler in the prosthetic body, the mould filled and degassed in the customary way is turned continuously through one or two axes before and during the curing of the two-component silicone rubber mass until the silicone rubber is vulcanised to such an extent that any rising of the filler materials is prevented.

Abstract: The present invention relates to a method for eliminating surface irregulties on the wraparound window of a torpedo nose array. The method broadly comprises the steps of preheating an oven to a temperature in the range of from about room temperature to about 160.degree. F., placing the nose array with the surface irregularities in the preheated oven, applying a vacuum at a pressure of up to about 10 mm of mercury, and maintaining the object in the oven under the conditions of temperature and pressure for a time sufficient to cause polymerization at the surface of the object and removal of gas bubbles, waves and blisters from the surface of the nose array. The method further comprises introducing an anhydrous gas such as nitrogen into the oven during the vacuum applying step.

Abstract: A hydroxylapatite base porous beads filler for use in cure of an injured or diseased part of bone of an organism. The porous filler is comprised of fired hydroxylapatite base beads each of which is formed with many pores. Each pore of the bead has a diameter of 1 to 100 .mu.m and a length larger than the diameter. Each bead has a porosity of 10 to 50% and a diameter of 0.02 to 20 mm. The pores of the bead may be filled with a solution containing a pharmaceutical in order to promote the cure of the injured or diseased part.

Abstract: Each of two screw bodies includes a feed screw and a kneading screw. The feed screw is formed of a wide-flight 1-lobe intermeshing screw designed so that the ratio W.sub.0 /D of the flight width W.sub.0 thereof to the screw diameter D ranges from 0.2 to 0.4. The kneading screw includes a plurality of double tipped kneading discs designed so that the ratio W/D of the width W thereof in the axial direction of the screw bodies to the screw diameter D ranges from 0.3 to 1.0, and displaced from one another in the circumferential direction of the kneading screw, the angle by which any two adjacent kneading discs being displaced range such that at least a backflow of an extrusion material can be prevented.

Abstract: The present invention relates to a packing method in which a material (p) is fed into a space comprising an opening (4c) for feeding the material and a space (4d) to be packed with said material, and said space is subjected to air tapping, that is, switching of air-pressure from a low air-pressure state to a high air-pressure state alternately, thereby packing the material into the space (4d) at a high packing-density. The use of air tapping for packing a material into a space makes the packing-density of the material uniform.

Abstract: A method for producing a polymeric optical guide including steps of allowing the patterned surface of a patterned substrate (1) on which the pattern of grooves to become capillaries is provided to contact with a plane substrate (2), forming capillaries (1a through 1f) from the grooves, filling the capillaries with a monomer solution (6) which is the material for the core of the optical waveguide utilizing a capillary phenomenon, and polymerizing the monomer solution.

Abstract: A process for producing a molded part made of expanded foam is configured so that the molded part can be produced with low vacuum and vapor requirements and has a very low residual moisture. This is achieved by using a mold whose walls forming the mold cavity themselves consist of material that conducts heat poorly or are suitably coated, by first evacuating the mold cavity, filling the evacuated mold with the expandable molding compound at excess pressure and, after the filling operation, introducing vapor into the evacuated mold. After turning off the vapor pressure, the mold cavity is again evacuated and the vacuum is maintained during the stabilization phase. After the stabilization phase, the mold is opened and the molded part is ejected by excess pressure (FIG. 1).

Abstract: Compositions, methods, and systems for manufacturing articles, particularly containers and packaging materials, having a starch-bound cellular matrix reinforced with substantially uniformly dispersed fibers. High strength articles that have adequate flexibility and toughness immediately or very shortly after being demolded without the need for subsequent conditioning are molded from compositions having a starch-based binder and fibers that are uniformly dispersed by means of a high yield stress fluid fraction within the starch-based composition. In a two-step mixing process, a preblended mixture is formed by gelating a portion of the starch-based binder or other thickening agent in water to form a liquid phase having high yield stress into which the fibers are substantially uniformly dispersed. The fibers preferably have an average length of at least about 2 mm and an aspect ratio of at least about 25:1.

Abstract: Processes for fabricating substantially void-free polymeric articles are provided. In one embodiment, a polymer melt is formed followed by extrusion through a die to form a polymeric extrudate. The polymeric extrudate is directly discharged vertically upward into an open-ended mold the open-ended mold having a longitudinal axis oriented substantially vertically. The polymeric article is cooled and removed from the mold. In a further embodiment, a mold is loaded with polymeric particles. The mold is oriented such that its longitudinal axis is substantially vertical. A vacuum is drawn on the loaded mold followed by heating the loaded mold above the melting point of the polymeric particles. After the polymeric particles are melted, the loaded mold is charged with an inert gas to above ambient pressure to collapse any remaining voids. The loaded mold is slowly cooled to form a polymeric article. Oriented polymeric bioabsorbable cannulated surgical articles and a method of making same are provided.

Abstract: A liquid crystal display element utilizing flexible gas barrier films decreases poor display performance caused by bubble formation. This decrease is achieved by reducing the permeation of gas and water vapor from the gas barrier films into substrates by devising the structure of the element and the configuration in which the element is mounted. Specifically, edges of the substrates forming the liquid crystal display elements are sealed. Additionally, the gas and water vapor saturation solubilities of the liquid crystal material is controlled to improve resistance to bubble formation. The liquid crystal display elements can also be subjected to and/or stored in a reduced pressure. Electronic equipment incorporating liquid crystal display elements can include a guard plate having a minimum thickness and/or spacing from the display elements.

Abstract: On mating surfaces of a pair of mold members are formed a breathing groove communicating with a cavity, a detection chamber for detecting a melt pressure at an end of the breathing groove, a detour groove diverging from the detection chamber and a valve chamber communicating with a vent passage at an end of the detour groove. A valve element of a shut-off valve member is positioned in the valve chamber and retracts to a valve closing position when the shut-off valve member moves in a direction perpendicular to and separating from the mating surface. A detection pin having an end fronting toward the detection chamber and a operation pin having an end fronting toward the valve chamber and abutting against the valve element are connected through a reverse mechanism so that the pins move in opposite directions to each other.

Abstract: A method for fabricating composite structures at a low-cost, moderate-to-high production rate. A first embodiment of the method includes employing a continuous press forming fabrication process. A second embodiment of the method includes employing a pultrusion process for obtaining composite structures. The methods include coating yarns with matrix material, weaving the yarn into fabric to produce a continuous fabric supply and feeding multiple layers of net-shaped fabrics having optimally oriented fibers into a debulking tool to form an undebulked preform. The continuous press forming fabrication process includes partially debulking the preform, cutting the partially debulked preform and debulking the partially debulked preform to form a net-shape. An electron-beam or similar technique then cures the structure. The pultrusion fabric process includes feeding the undebulked preform into a heated die and gradually debulking the undebulked preform.

Abstract: Surface characteristics of cast molded contact lenses are improved by removing substantially all the oxygen from the plastic mold pieces prior to casting the lenses.

Abstract: A method is described for making reinforced intermetallic matrix composites containing oxide ceramics. The method involves the oxidation of intermetallic powders under optimum conditions in an atmosphere containing oxygen, and the hot-pressed sintering process of oxidized intermetallic powders. The mechanical properties of intermetallic/oxide composites are superior to those of non-oxidized intermetallic sintered bodies.

Abstract: Methods and systems for readily and economically manufacturing hydraulically settable articles, particularly containers, from microstructurally engineered hydraulically settable mixtures. The mixture is pressed between a male die of a desired shape and a female die having a substantially complimentary configuration of the male die shape to immediately fashion a portion of the mixture into a form stable shape for the desired article. To assist in imparting form stability, the dies can be heated or cooled. Once the article has obtained form stability, the article is removed from the dies and dried under heated air to gain strength. The article can then receive printing or a coating, if desired, prior to packaging, shipping, and use.

Abstract: The invention relates to a method for manufacturing a foaming synthetic material, for example, polystyrol, by means of an extruder, in whose entry the synthetic material is fed, to which by means of a fumigation aperture foaming gas in a liquid form, for example pentane, is introduced at a pressure maintaining the foaming gas in its liquid form, whereby throughout a following extruder region, the synthetic material provided with the foaming gas is homogenecised.

Abstract: A method of manufacturing a medical prosthetic article by injecting a thermoplastic resin into the cavity of a plaster mold, comprising the steps of: confining first and second plaster molds having porous structures respectively in first and second mold bodies made dividable from each other, the first and second plaster molds defining therein a cavity having first and second inner faces, a contour of a medical prosthetic article to be molded, a sprue runner communicating with the cavity, and an air vent communicating with the cavity; sealing up the cavity not only from the ambient air but also from the porous structures of the first and second plaster molds, when the first and second mold bodies are closed; evacuating the cavity through the air vent; and injecting a thermoplastic resin through the sprue runner into the cavity under a predetermined degree of vacuum.

Abstract: A method for making polyurethane acoustic windows. A molding material is lied to a reservoir connected to the bottom of the mold to fill the mold under the influence of a vacuum applied at the top of the mold. After initialling filling the mold, a second reservoir connects to the vacuum port and additional material is added to the first reservoir to partially fill the second reservoir. Thereafter the mold with the reservoirs attached is located in a pressure oven for curing. After curing the mold an acoustic window is removed from the mold for post molding operations.

Abstract: A plastic molding method for semiconductor devices, the method including placing semiconductor devices mounted on lead-frames between lower die cavities in a lower die chase block and upper die cavities in an upper die chase block and clamping the upper and lower die chase blocks together; evacuating an ejector chamber in the lower die chase block through a lower die common surface table, evacuating an ejector chamber in the upper die chase block through an upper die common surface table, and evacuating a parting chamber at a parting surface between the lower die chase block and the upper die chase block through one of the lower die common surface table and the upper die common surface table; and injecting a sealing resin into the upper die cavities and the lower die cavities to plastically package the semiconductor devices.

Abstract: An apparatus for filling and assembling mold parts for a contact lens includes a first automated station for receiving a plurality of front curve contact lens mold parts and depositing in each front curve mold a predetermined amount of a polymerizable monomer or monomer mixture, and, a second automated station for receiving the plurality of front curve mold parts and assembling each front curve mold part with a back curve mold part under vacuum to prevent entrapment of gas between the mold parts. The front curve mold parts are transported to the first and to the second automated stations by a pallet having registration guides that cooperate with the second station to register the pallet prior to assembly of the mold parts.

Abstract: Process for direct production of shaped packaging material made of thermoplastic polyesters with no effect on the taste of foods packaged in them, where the diol component of the polyester consists of at least 70 wt % ethylene glycol, and the polyester is produced in the presence of the usual catalysts plus additional cobalt or cobalt and manganese compounds and phosphorus compounds. An inert gas is introduced into the polyester melt and distributed uniformly in the melt immediately after its discharge from the polycondensation reactor, 0.05 to 1.0 wt % of an amide compound with a low volatility is added to the polyester melt directly next to the gas inlet. Finally, the polyester melt is subjected to a vacuum degassing immediately before the shaping apparatus and the melt is sent directly to the shaping apparatus within a maximum of 30 minutes after its discharge from the reactor at a maximum temperature of 35.degree. C. above the crystallite melting point of the polyester.

Abstract: Multiple sequential chemical reactions on a polymeric feedstock are carried out in an extruder with multiple reaction zones. Each reaction zone has means for introduction of reagents, for mixing of reagents with polymer and for removal of by/co-products or unreacted reagents.

Abstract: A two phase liquid mixture of a thermoplastic synthetic resin melt and an aqueous phase, such as a latex coagulate, is dewatered in a counter-rotating twin screw extruder under a pressure which is greater that the water vapor pressure at the temperature of the melt of the thermoplastic synthetic resin by conveying the melt into partially filled screw channels in the dewatering zone and restricting it in at least one of these screw channels in the entry nip of the twin screws to create a local, narrowly limited, steep pressure gradient and to form a coherent melt cake, and draining the water in liquid form from beneath under gravity upstream from the boundary of the melt cake so that the melt cake does not stand in contact with a coherent aqueous phase.

Abstract: Low cost broadband infrared windows are fabricated using a near net shape process which greatly reduces the cost of machining and grinding window materials. The fabrication of zinc sulfide (ZnS) IR windows uses ceramic powder processing to avoid the expensive prior art chemical vapor deposition method. Further, the invention involves a means of hardening and strengthening ZnS as part of the powder process, with IR transmission performance comparable to undoped CVD-prepared ZnS. The compositional modification used in the practice of the invention involves the introduction of gallium sulfide (Ga.sub.2 S.sub.3) as a second phase which acts to toughen and harden the ZnS. The process of the present invention achieves a hardening effect without degrading the IR transmission properties also by means of controlling the polycrystalline microstructure grains to a very small size. At the same time, porosity, which strongly degrades IR transmission, is minimized by full densification.

Abstract: A process for molding dimensionally accurate plastic articles using a low pressure injection molding technique. The process utilizes a two-piece silicone rubber mold having a cavity representative of the shape of the article to be molded. The mold is substantially encased on all sides in a rigid mold box to prevent deformation of the cavity during the molding process (10). The mold box and the encased mold are placed in a vacuum chamber, and a vacuum is drawn on the chamber to evacuate the cavity (20). A predetermined amount of a reactive mixture is simultaneously mixed and injected under pressure into the mold to form the plastic article (30). The amount of material injected is sufficient to fill the cavity but not sufficient to distort the cavity. The chamber is vented (40) and the mold is removed from the mold box (50). The mold is flexed in order to remove the plastic article from the mold (60).

Abstract: The present invention relates to a process for minimizing the flow instability of molten plastics caused by slippage of the melt at the die wall during the extrusion process. The slippage, and therefore the flow instability, is minimized by removing the air from, or "degassing", the polymer prior to the extrusion process, preferably by subjecting the molten polymer to a vacuum for an extended time, typically 24 hours. Further, air is preferably prevented from being introduced into the molten polymer, the extrusion die or the extrusion process from the ambient conditions surrounding the extrusion process during the extrusion process by creating a vacuum over the polymer hopper, the feed region of the extrusion system, the exit portion of the die, the entire extrusion system or any combination thereof.

Abstract: A method of manufacturing a bobbin made essentially or partially of a curable resin comprises the steps of: a) providing a mold consisting of a male portion and of a female portion, the gap left between the said female and the male portions, in their operational mounted position, being of the shape and dimensions of the bobbin which it is desired to produce, the mold being provided with a resin inlet and vacuum port in communication with the gap; (b) laying on the surface of the male part of the mold, or winding thereon, any element or material which it is desired to embed within the resin; c) inserting the male part of the mold into the female part thereof and securely connecting the two parts, the two parts, when connected, being essentially sealed against pressure loss along their contact surfaces; d) causing a curable resin to flow into the gap through the resin inlet, while applying a vacuum at the vacuum port, until the empty space provided within the gap is substantially entirely filled with resin; e)