Abstract: Tube units useful for a variety of application are provided. Preferably, individual laminated tubes are joined to each other by intermediate pieces to produce a wide ribbon of parallel tubes. The tubes are porous to certain substances, allowing them to serve as an apparatus to exchange material between two or more fluid streams. The tubes are particularly useful as membrane modules for exchange of material between two fluids. Continuous and discontinuous methods for constructing such tube units are also taught.

Abstract: The present invention relates to an apparatus for automatically blowing a bubble in the production of tubular biaxially stretch oriented thermoplastic flexible film by the "bubble" method comprising a high flow fluid conduit having a proximal end for introducing a high flow fluid, and a distal end substantially perpendicular to said proximal end, and having attached to said distal end a bullet mounted proximate to the distal end of the high fluid flow conduit through which the high flow fluid may pass into the tubular thermoplastic film; a cutting device located on said high flow fluid conduit and in line with the bullet, said high flow fluid conduit, bullet, and cutting device disposed downstream from a first and second pair of rolls defining the bubble; and an automatic bubble blowing control system means comprising means for controlling the flow of fluid into the interior of the tape, and means for controlling the speed of a driven set of squeeze rolls located downstream from the high flow fluid conduit.

Abstract: An apparatus for the manufacturing of plastic pipes has half shells of which two at a time combine as a pair to form a mold. It is provided with a temperature-regulating bell. Supply lines are formed as flexible supply hoses of temperature-resistant plastic material. A line conduit accommodating them is provided with a protecting tube, which accommodates the supply hoses and which is provided with a heat insulation towards an injection head.

Abstract: A method for manufacturing plastic pipe such that the pipe has apertures formed therein when the pipe is viewed in cross-section, comprising the steps of having hot plastic flow through a die and subsequently be extruded through a die head to form an extruded wall component having first and second end wails, with the die head having formed therein a plurality of first sized gaps and a plurality of second sized gaps, with the second sized gaps having an aperture located inside each of said second sized gaps. The die is secured to a manifold assembly, with the manifold assembly comprising sets of tubes located centrally of one another, each set of tubes comprising a water inlet tube, a tube through which a vacuum is pulled, and a water return tube. Each set of tubes is positioned longitudinally within a respective die manifold tube with the outermost surface of each set of tubes spaced a first distance from the respective die manifold tube. Each of the respective die manifold tubes extends through the die.

Abstract: The method of making polystyrene foam for foam products which includes utilizing atmospheric gases as the blowing agents or preferably mixing one or more of these gases and a blending agent which is non-volatile at the extrusion temperatures, introducing the mixture to a molten thermoplastic polystyrene resin containing nucleating agents such as sodium bicarbonate and citric acid and extruding the thermoplastic in the form of a foam. The resultant foam has substantially no residual blowing agent, is dimensionally stable at ambient temperatures and when used with a non-volatile blending agent can be made with small amounts of blowing agent permitting cooling of the melt without high loading on the extruder. The foam may be coextruded with one or more layers of thermoplastic film so that the resultant product is adapted for use for plates, cups, food containers or packaging and for labels for containers such as glass and plastic containers and for labels that are shrunk in place on a container.

Abstract: A flattening and removing device for a plastic tubular film web produced by a stationary film blowing head in a blowing process has two deflecting rollers and two turning bars. The first deflecting roller and the squeezing roller are mounted parallel to each other between mounting plates that are rigidly connected to a turntable mounted in turning fashion in the frame floor. The second deflecting roller is connected by a support frame to a retainer having ends which are connected to gearwheels in eccentric fashion. The turning bars are each connected by support frames to gearwheels, and the center lines of all the gearwheels are aligned with each other and with an imaginary swivel axis. Thus, the diameter of the turning bars can be increased to the desired degree without impeding the passage of the flattened tubular film when the device is installed.

Abstract: A method and apparatus for molding an inflation film even from a thermoplastic resin having a small melt tension, in which a melt resin bubble extruded from an extruder is molded, while controlling a resin temperature of the bubble to a certain temperature range by an air ring provided with a plurality of annular slits for blowing cooling air in a take-up direction of the melt resin bubble and provided at a position at which the melt resin bubble is remarkably expanded, after (a) cooling air is blown to a melt resin bubble from a first air ring provided at the proximity of a die outlet to cool said melt resin bubble; and, then, the bubble is either (i) brought into contact, on the inner surface thereof, with the surface of a stabilizer provided on a die surface, or (ii) is supported in a non-contact state through an air layer, while being taken up.

Abstract: A method and apparatus is provided for forming clear shrinkable film material for use as labels on containers. A blend of general purpose polystryene and styrene-butadiene or styrene butyl acrylate is extruded from an annular extruder die orifice to form a frustoconical tube which is stretched before cooling air is applied to form a clear film that has machine direction orientation and cross direction orientation that can be used as a shrinkable label on containers. As the tube is extruded, it is shielded from cooling air which is applied downstream from the extruder die orifice. The apparatus shields the hot annular extruded material adjacent the die orifice. The air is supplied downstream from an annular air orifice which is designed with a taper that allows ambient air to be freely drawn in and eliminates what would be a negative pressure zone immediately downstream of the air orifice while eliminating air turbulence and improving cooling.

Abstract: A method of manufacture of an ultra-high molecular weight polyethylene thin-wall pipe which is uniform in thickness and free from a folded mark. The ultra-high molecular weight polyethylene thin-wall pipe is manufactured by supplying ultra-high molecular weight polyethylene into and melting and kneading, continuously extruding the molten substance of the ultra-high molecular weight polyethylene from a die connected to a screw of the screw extruder to form a cylindrical roughly shaped article, and diametrically expanding the cylindrical roughly extruded article by means of a tapered core and taking up.

Abstract: An apparatus for the formation of a foamed polyolefin sheet provided with a cylindrical cooling device for cooling a foamed extruded tubular body at one end of an extruder, air outlets for increasing the internal pressure of the cooled foamed tubular body at a region between the extruder die and the upstream section of a cylindrical cooling device and between at least two adjacent sections of a cylindrical cooling device and a cutting blade for slitting the foamed tubular body enables the production of foamed polyolefin sheets with improved surface characteristics and strength.

Abstract: A foamed polyolefin sheet is formed by extruding a molten polyolefin resin, which contains a blowing agent, into a low-pressure zone through an annular die provided at an end of the extruder to form a foamed tubular body, bringing the foamed tubular body into contact with a peripheral surface of a cylindrical cooling device to cool the foamed tubular body and then slitting the thus-cooled foamed tubular body and then slitting the thus-cooled foamed tubular body in the direction of extrusion to open same. The cylindrical cooling device is divided into an upstream section and at least one other spaced downstream sections. The internal pressure of the foamed tubular body is increased to from about 5.times.10.sup.-4 to 3.times.10.sup.-2 kg/cm.sup.2 (G) between the die and the upstream section of the cylindrical cooling device and also between at least two adjacent sections of the cylindrical cooling device to apply tension to the foamed tubular body at the inner wall and prevent the formation of corrugations.

Abstract: A method of creating a score in a pouch formed from a thermoplastic film is described. Ultrasonic energy is used to create the score in a film that is later formed into a pouch. The score can be used to open the pouch by pulling opposite sides of the scored area. The ultrasonic force is applied to the film as a part of a downstream process in a blown film manufacturing line to produce the pouch.

Abstract: An improved adjustable diehead assembly for mounting on a plastic extrusion machine is described. A discharge orifice for a parison of plastic is formed by a mandrel and annular member. The annular member is moveable by a holder assembly perpendicular to axis of the mandrel to adjust the orifice. The holder assembly includes cams which act upon the opposed sections of the outside surface of the annular member to adjust the orifice when first and second screws are tightened. A third screw acts upon the annular member to adjust the orifice. The screws are mounted on a front part of the holder assembly on the diehead to allow adjustment of the orifice even when the extrusion machine is operating.

Abstract: The method of making polystyrene foam for foam products which includes utilizing atmospheric gases as the blowing agents or preferably mixing one or more of these gases and a blending agent which is non-volatile at the extrusion temperatures, introducing the mixture to a molten thermoplastic polystyrene resin containing nucleating agents such as sodium bicarbonate and citric acid and extruding the thermoplastic in the form of a foam. The resultant foam has substantially no residual blowing agent, is dimensionally stable at ambient temperatures and when used with a non-volatile blending agent can be made with small amounts of blowing agent permitting cooling of the melt without high loading on the extruder. The foam may be coextruded with one or more layers of thermoplastic films so that the resultant product is adpated for use for plates, cups, food containers or packaging and for labells for containers such as glass and plastic containers and for labels that are shrunk in place on a container.

Abstract: An apparatus for highly intensive cooling of biaxially oriented films from high- and medium-molecular weight thermoplastics using a long neck on a blown film line is described, including: a plastics extruder, a die for forming a tube neck from the extruded plastic, means positioned adjacent the die for externally cooling the tube neck, an expansion zone where the tube neck becomes a bubble, a drag mandrel positioned immediately before the expansion zone for internally contacting, stabilizing and guiding the tube neck, means for continuously providing cool air internally of the tube neck at the expansion zone immediately after the contact, the means including a first tube in communication with a cool air source, and means for continuously removing the cool air that has been heated.

Abstract: An extruder head for making an anticorrosive tubular polymeric film has a body having an extrusion die, a hollow core mounted in the body and extending through the extrusion die, a molding passage terminating in an annular opening. Chambers are defined in the body of the core and die in the zone of the annular opening, the core chamber communicating with a passage for supplying a corrosion inhibitor, A pipe for supplying compressed air is provided in the interior of the core for blowing polymer melt into a tube. A scroll having a tangential nozzle for supplying compressed air is secured to one end of the pipe and is provided with a diaphragm in the form of a converting tube coaxial therewith and communicating with the chamber of the extrusion die. The other end of the pipe is made in the form of an opening-forming diverging tube.

Abstract: The invention provides a new air ring of single or dual orifice type for use as a primary or secondary ring to cool a blown extruded tube of molten plastic material, and also to stabilize the moving tube. The air from the ring is kept in contact with the tube outer surface as much as possible by a chamber surrounding the tube. Maximum cooling requires maximum air velocity and in prior art apparatus this may then cause generation of vibrations of the bubble, resulting in non-uniform film, or even disruption of the bubble. The air volume and velocity must therefore be restricted to ensure that this does not happen. In the new air rings the side wall of the chamber diverges outwards in the direction of bubble movement with an end wall closing the downstream of the chamber and forming a short narrow orifice. The chamber is provided with a plurality of thin annular partition members which extend radially inwards so that their inner edges are close to the bubble wall to provide respective short, narrow gaps.

Abstract: Method in manufacturing a heat insulated tube includes a tube (17) for conducting fluid and a sheath (12) enclosing said tube, a heat insulating material (15) being disposed between the fluid tube and the sheath. The sheath is being extruded in an angle extruder die (10) while the fluid tube and the heat insulating material enclosing said tube are being fed axially through the angle extruder die as the sheath is being extruded around the heat insulating material. Then the sheath (12) extruded from the angle extruder die is kept spaced from the heat insulating material (15) enclosing the fluid tube (17), over an initial length of the axial movement thereof up to chains of chill molds (13) for imparting to the sheath a corrugated shape by forming the sheath against the chains of chill molds under the influence of negative pressure. The invention also relates to a device in extruders having an angle extruder die (10) for the manufacture of the heat insulated tube.

Abstract: A method of consolidating a tubular composite article of polymeric matrix material and fibrous reinforcing material, comprising enclosing a length of the tubular composite article in a tubular protective member and advancing the protective member to carry the length of the article thus enclosed through a consolidation zone wherein the article is progressively subjected to consolidating temperature and pressure. The method enables the composite to be pulled through the consolidation zone without the distortion which tends to occur in standard "pultrusion" methods owing to surface friction and longitudinal tension on the composite.

Abstract: A high-strength cross-laminated film with a foam core, particularly a cross-laminated film made by counter-rotating dies, and a method of producing the laminated film. The high-strength cross-laminated tubular film web is produced by counter-rotating dies; which will allow for the orientation of each extruded film layer in a different direction so as to form a cross-laminate, and whereby, concurrently with the extrusion of the molten layers, there is interposed a formed adhesive material polymer between the layers so as to provide a weak bonding or adherence therebetween while imparting a thick feel to the laminated film.

Abstract: Long lengths of a heat-shrinkable sleeve for use in splicing electrical cables and the like are manufactured by providing an elongated impermeable core having a smooth outer surface, extruding an elongated sleeve around and in contact with the core, the sleeve having a smooth inner surface conforming to the outer surface of the core, and effecting an initial expansion of a portion of the sleeve to a larger diameter in an expansion zone so that the sleeve separates from the core and leaves a space between the sleeve and core. A fluid is introduced into the space under pressure via a fitting at the downstream end of the sleeve while continuously advancing the sleeve and core through the expansion zone. To begin the process, a permeable core is used, and the sleeve is extruded around and in contact with the permeable core.

Abstract: This invention discloses a new bubble forming and stabilizing device for use in a continuous extrusion process for making a blown film and a process for using same. The apparatus comprises a bowl shaped mandrel mounted subsequent to a die, the mandrel has an undersurface extending substantially parallel to and space from the path of travel of the blown film from the die and the undersurface is contoured to guide a stream of cooling air along its surface between the undersurface and the blown film as the blown film emerges from the die. The apparatus allows for increased production rates and improved physical properties of the forming bubble by creating more efficient heat transfer from the forming bubble to the cooling air stream. The device also provides support for the molten bubble during its most unstable state.

Abstract: The rate for producing blown films of thermoplastic resins may be increased by using the extrusion and blowing apparatus of the invention, which includes a means of rapidly cooling the blown film at points both above and below the bubble frost line.

Abstract: Apparatus for extruding a pliable, thin-walled tube comprising an extrusion and shaping die assembly comprising an annular die body, a mandrel supported within the annular die body, a mandrel extension mounted on the mandrel adjacent the die outlet, the mandrel extension having a diameter less than the diameter of the mandrel, a sizing disk supported by the mandrel extension, and a source capable of supplying molten polymeric material to the die assembly under pressure to force the material through an annular extrusion flow channel around the mandrel and out the die outlet thereby forming a moving tube of the material, the mandrel extension extending outwardly from the die in the direction in which the tube is extruded, the annular die body having at least one fluid passageway to channel fluid introduced under pressure into the annular die body axially through the mandrel and outwardly from the axis of the mandrel extension to form an air pillow adapted to cool and support the tube around and spaced from the

Abstract: The invention provides a new air ring of single or dual orifice type for use as a primary or secondary ring to cool a blown extruded tube of molten plastic material, and also to stabilize the moving tube. The air from the ring is kept in contact with the tube outer surface as much as possible by a ring "chimney" surrounding the tube. Maximum cooling requires maximum air velocity and in prior art apparatus this may cause generation of vibrations of the bubble, resulting in non-uniform film, or even disruption of the bubble. The air volume and velocity must therefore be resricted to ensure that this does not happen. In the new air rings the side wall of the chimney diverges outwards in the direction of bubble movement to form a chamber, an end wall closing the downstream end of the chamber turning suddenly radially inwards toward the bubble to form a short narrow orifice.

Abstract: An extrusion die, particularly for double-walled corrugated thermoplastic pipes, including an extrusion head, a nozzle, two concentric hollow mandrels carrying die lips and an additional cooled and vacuumed mandrel. The vacuum is maintained between the latter and the inner wall of the pipe to prevent retraction of the wall from the mandrel until the wall is set.

Abstract: Apparatus for the external support of tubular films of thermoplastic material consists of groups of outwardly curved supporting segments disposed successively in the direction of withdrawal of the tubular film. These supporting segments are adjustable simultaneously and in the same sense to different tubular film diameters, and for their adjusting movement they are each connected with a turning bar which is common to all supporting segment groups and journalled in a supporting frame and with a holding bar aligned parallel thereto which again is common to all supporting segment groups.

Abstract: A bubbler stabilizer for a blown film extrusion apparatus has a shaft mounted on an extrusion die of the apparatus, a pair of supporting members mounted on the shaft and spaced a predetermined distance from each other, and a plurality of lengths of coil spring extending between the peripheral portions of the supporting members with the lengths being spaced peripherally at intervals of a predetermined size around the supporting members. The coil spring lengths extend in a skew position relative to the axis of the shaft.

Abstract: Extrusion apparatus for producing a continuous molten tube of a film-forming material includes an extrusion die defining an annular extrusion orifice between adjustable die lips through which a heat-plastified, synthetic, resinous, extrudable film-forming material is extruded in a radial direction. An annular gas bearing in spaced relationship to the orifice redirects the film into a tubular shape. In one die arrangement extrusion takes place radially outward, whereas in a second die arrangement extrusion takes place radially inward.

Abstract: A method and apparatus for producing mesh film include an extrusion die for extruding a tube of a heat-plastified, resinous, mesh film material. A first cooling arrangement, centrally located within the extruded tube, cools the internal surface of the tube. The first cooling arrangement has an outer diameter substantially equal to the inner diameter of the extruded tube. A plurality of cooling nozzles are disposed radially outward from the first cooling arrangement for directing a plurality of streams of a cooling gas toward the exterior surface of the extruded tube. An annular gas bearing is spaced axially from the first cooling arrangement such that the extruded tube passes therethrough after leaving the first cooling arrangement, thereby permitting the diameter of the extruded tube to be increased subsequently by means of a trapped air bubble therewithin.

Abstract: A vinylidene fluoride resin film having (1) a crystal melting point of 182.degree. C. or higher as measured by differential scanning calorimeter in nitrogen atmosphere at a temperature elevation speed of 10.degree. C./min; (2) a diffraction point corresponding to (1 1 .zeta.) of the .alpha.-phase crystal in the wide angle X-ray diffraction photograph; and (3) an orientation degree of the crystal of 0.85 or more when measured under irradiation of X-ray incident vertically on a major surface of the film. The vinylidene fluoride resin film is obtained by inflation accompanying melt necking stretching. The film has improved mechanical properties and heat-stability and is also adapted for use as a base film of a metallized film.

Abstract: A process for producing an air-permeable film is described, comprising stretching in at least one direction a film made of a composition comprising 42 to 87 vol % of a polyolefin resin and 58 to 13 vol % of an inorganic filler and further containing an aliphatic alcohol/fatty acid ester of a fatty acid having 10 to 22 carbon atoms and an aliphatic alcohol having 1 to 12 carbon atoms in an amount of 3 to 25 parts by weight per 100 parts by weight of the above composition.

Abstract: Apparatus for preparing seamless, creaseless, pliable, thin-walled tubes comprising means to extrude a moving continuous tube of polymeric film material from a die, means to radially stretch the continuous tube as it emerges from the die, means to longitudinally stretch the tube, and means to sever the tube while the tube is in motion to form tube segments while maintaining the tube substantially free of creases. This apparatus may be employed in a process to prepare seamless, creaseless, pliable, thin-walled tubes.

Abstract: Cooling apparatus for air-cooling tubular plastic film which has been extruded from a film blowing head comprises spaced apart cooling rings, which in the direction of extrusion succeed the annular extrusion die of the film blowing head and are substantially concentric to the axis of the extruded tubular film and have air-guiding surfaces facing the surface of the tubular film and define annular nozzle gaps for delivering cooling air, which flows in contact with said air-guiding surfaces. The air-guiding surfaces are convexly curved in a longitudinal sectional view of the cooling rings. The nozzle gaps are defined by rings which in the direction of flow of the cooling air precede the cooling rings and which are so arranged that the cooling air discharged from said nozzle gaps flows in a direction which is approximately parallel or at an acute angle to the direction of travel of the tubular film.

Abstract: Apparatus for cooling tubular plastic films extruded from a film blowing head. Air cooling means consisting of co-axial pipes extending axially through the film blowing head supply the cooling and inflating air and withdraw the same from the inflated parison. Vertically inner cooling rings are disposed substantially concentrically to the axis of the parison downstream of the annular extrusion die orifice of the blowing head. The inner cooling rings define nozzle gaps and have air guiding surfaces, which face the wall of the parison and are convexly curved in a longitudinal section of the inner cooling rings and during the operation of the apparatus are swept by the cooling air blown out of said nozzle gaps. An outer cooling air jet concentrically surrounds the extruded parison and serves to blow air in a direction which is approximately parallel to the direction of travel of the parison. The inner cooling rings are concentric to the parison.

Abstract: Pipelines for transporting sewage, water, slurries, liquid and gaseous hydrocarbons, and like materials are interlined with a composite tubular lining having an inner skin layer and a foamed layer contiguous with the inner skin layer. The foamed layer is either contiguous also, along its opposite surface, with the inner wall of the pipe or may be spaced therefrom by an outer skin layer of the composite lining. The lining may be applied either before the pipeline is placed into service or afterward, whether in situ or removed for maintenance or repair. For application in situ the lining is preferably more flexible than will suffice for insertion into new pipes.

Abstract: A process for extruding biaxially oriented high density polyethylene film in which an additional secondary gaseous cooling medium is applied at strategic strain inducing locations of the blown bubble to control the final product properties of the extruded material.

Abstract: Apparatus for cooling plastic film or sheet obtained by blowing tubing, comprising at its intermediate section an intensive blowing ring for directing air towards the tubing and at its upper section an upper chamber in which the tubing is in contact with an air flow directed in the drawing direction of the tubing. At the lower section of the apparatus is a non-closed lower chamber provided with at least one opening. The apparatus can be used to form blown films having superior optical properties, particularly clarity and turbidity, from a large number of resins.

Abstract: A high stalk blown film extrusion apparatus and method is described which produces a stabilized high stalk for increasing the production rate of blown, low to high molecular weight polymers, while increasing the film's physical and mechanical properties. The high stalk is stabilized by application of high velocity, low volume flow rate of air over the interior and exterior surfaces of the extruded film.

Abstract: A process for producing an air-permeable film, which comprises:(a) biaxially stretching a tubular unstretched film of a composition comprising 42 to 87 vol % of a thermoplastic resin and 58 to 13 vol % of an inorganic filler along a truncated-conical mandrel;(b) blowing a gas over the outside of the biaxially stretched tubular film to cool said film; and(c) simultaneously blowing a gas continuously into the tube of the film so as to penetrate the gas through the film and go outside.

Abstract: Equally biaxially oriented film is produced by extruding liquified polymer in tubular form, orienting the tubular film in the radial direction only and then either (1) equally orienting the radially oriented film in the longitudinal direction and drying the resultant equally biaxially oriented film while preventing any shrinkage thereof or (2) orienting the radially oriented film in the longitudinal direction to a degree less than said radial orientation but equal to the radial orientation remaining after the biaxially oriented film undergoes radial shrinkage upon drying thereof in the absence of radial shrinkage control and drying the resultant biaxially oriented film in the absence of radial shrinkage control.

Abstract: Extrusion apparatus wherein a hollow cylindrical workpiece is advanced over the outer surface of a mandrel and through an extrusion die by motive force applied to the outer surface of the workpiece by an advancing drive member having an inner surface in operative engagement with the outer surface of the workpiece to produce a hollow cylindrical product of reduced diameter, and wherein a first moving force is required to produce relative movement between the mandrel and the workpiece and wherein a second moving force is required to produce relative movement between the drive member and the workpiece, the improvement wherein various structure are provided for reducing the first moving force relative to the second moving force to enhance the extrusion process and thereby increase its efficiency.

Abstract: A method and apparatus for internal cooling of extruded tube-shaped objects wherein liquid nitrogen is inserted into the tube and evaporated there out of contact with the tube on account of the heat from the tube whereafter only evaporated nitrogen is made to pass through the inner surfaces of the extruded tube. The apparatus for evaporation of the liquid nitrogen and for conduction of the gasified nitrogen comprises a cylinder-shaped member with good thermal conductivity placed in the shaped tube adjacent to the extruder nozzle. Provided in the closed end of the cylindrical member are nozzle members with a connection to a supply line for liquid nitrogen inserted through the extruder nozzle. Provided in the opposite end of the cylindrical member are openings for passage of the evaporated nitrogen out towards the shaped tube.

Abstract: A process at continuous blowing of film such linear thermoplastic materials which after that the plastic melt has left an annular die, when introducing gas to the inner of the tube, forms a neck part having an essentially constant diameter and then forms a rapidly expanding main bubble whereby the speed of the film at the upper part of the neck is kept above 15 m/min.

Abstract: A process of manufacturing carcass bands which are reinforced by cords and are to be employed in fabricating a radial tire.

Abstract: A tubular film process wherein molten resin is extruded from an extrusion die into a tubular resin, blown by an internal pressure, cooling air is discharged at least at a point between the vicinity of the extrusion die and the vicinity of a bubble expansion ending point in a direction of the extrusion of the resin and in a direction opposite to the extrusion of the resin to, thereby cool the tubular resin, and the tubular resin is continuously taken up upon being cooled and solidified. The cooling air has higher flow rate in the extrusion direction. The cooling air is discharged not only in the direction of the extrusion of the resin but also in the direction opposite to the extrusion of the resin, whereby hot air stream is prevented from accompanying the flow of the resin, thus enabling to effectively cool the tubular resin.

Abstract: An improved method and apparatus for fabricating insulated cables, particularly polymeric insulated electrical power cables, resistant to the formation and growth of electrochemical trees is disclosed. Internal pressure on the conductor side of the cable is maintained lower than the external pressure on the outer surface of the insulation during extrusion. Extrusion pressure higher than the external pressure results in expansion of the insulation following extrusion. This expansion or swelling reduces the number and size of cracks and voids which are precursors of electrochemical trees. In addition, pressure curing the extruded, insulated cable with a curing medium above its melting point followed by gradual gradient cooling under internal pressure and higher external cooling fluid pressure to around room temperature optimizes the resistance of the cable to nucleation and growth of electrochemical trees.

Abstract: Long lengths of a heat-shrinkable sleeve for use in splicing electrical cables and the like are made in a continuous process. The sleeve is formed around a permeable core, and the core and sleeve are advanced together in an axial direction, the leading end of the advancing sleeve being hermetically sealed. The core and sleeve pass through a heating station, thereby heating a portion of at least the sleeve, and a fluid is introduced under pressure into the core, thereby internally pressurizing the sleeve to effect a radial expansion of the heated portion thereof. The core and sleeve then pass through a cooling station, thereby cooling the expanded sleeve to stabilize it. A stress graded compound also for use in splicing electrical cables and the like is made by heating a dimethyl silicone liquid to remove entrapped gas and mixing the liquid with a silicone carbide powder having a particle size capable of passing through a 400 mesh screen.

Abstract: A hose construction and method of making same are provided wherein such hose construction comprises a polyolefin tube which has a tubular fluorocarbon barrier layer defining the inner portion of the tube and such barrier layer renders the tube substantially impermeable to the passage of nonpolar hydrocarbons present in the fluid being conveyed through the hose.

Abstract: A hollow synthetic profile is cooled during extrusion by direct heat exchange through the introduction of under-cooled liquid nitrogen under a pressure of 2 to 8 bar into the hollow interior by means of a boring in the arbor of the extrusion tool with an insulated capillary tube forming the cooling medium line.