Abstract: Provision is made for evenly controlling the cooling of the inner die pin of an extrusion die assembly so that the hot plastic coming in contact therewith is frosted. A conduit extends through the inner die pin to a point near the tip of the inner die pin. A cap is mounted on the end of the conduit and spaced from the front face thereof to provide an annular discharge opening. At least the tip portion of the inner die pin is formed of a material of good heat conductivity, such as brass, and the cooling air is directed through the discharge opening relatively evenly over the inner portion of the inner die pin to effect uniform inside frosting of a plastic tube formed in the apparatus. The inside of the plastic tube is open to the atmosphere.

Abstract: Disclosed is a process for the continuous manufacture of fiber-reinforced tubing based on cellulose hydrate, comprising the steps of impregnating and coating fibrous tubing with an aqueous akaline viscose solution; moving the viscose-treated tubing at a steady speed vertically in a straight line along its longitudinal axis; applying a viscose-regenerating fluid along at least one circular circumferential line to at least the outside of the viscose-treated fibrous tubing; immediately after the application step, passing the tubing with the film of regenerating fluid on its surface through at least one first air section, whereby there is produced a fiber-reinforced tubing based on cellulose hydrate; treating the cellulose hydrate tubing with an aqueous fluid containing a dissolved chemical plasticizer; and drying the plasticized tubing. Also disclosed is an apparatus for carrying out this process.

Abstract: Apparatus as set forth in U.S. Pat. No. 3,796,781 for the production of quenched tubes of plastics materials, wherein the peripheral portions of the caibrating disc assembly that contact the wall of the tube during operation of the apparatus comprise a liquid absorbent material.

Abstract: In the process of extruding tubular thermoplastic film or tape, the production rate can be improved by using a smooth support plug to stabilize and shape the extrudate after it has been cooled and at least partially solidified. A principal function of the support plug is to assist in supporting the long slender column of partially solidified extrudate which is above the plug. The result is a significant increase in the output of the extrusion process.

Abstract: An extrusion system for the production of foam boards, billets and the like products includes an extruder (20) at a first higher elevation (22) extruding foamable resin through a die in the upper end of an elongated vacuum chamber in the form of an inclined barometric leg (26) which extends at its lower end into a shallow but large surface area pool (39) of liquid such as water. An elongated shroud or hood (44) on the lower end of the leg reduces the pressure head of water above the foam product as it exits the leg and moves out of the pool for processing at a lower second elevation. The large area of the pool reduces its depth for a given volume and minimizes fluctuations in the level of the pool and the pressure head above the product when the vacuum changes. In one embodiment the pool extends beneath substantially the entire floor of the building (30) enclosing the second lower elevation (31) in which the subsequent processing occurs.

Abstract: A method of making elongated members of thermoplastic material which simulate natural bamboo by continuously extruding the material through a die, cooling the extruded material downstream of the die, gripping the cool material and transporting the material away from the die and slowing the speed of transport relative to the speed of extrusion at predetermined lengths of extrusion to produce regions of greater external cross-sectional dimensions to provide axially spaced nodes similar to those of bamboo.

Abstract: A quench bath for cooling an axially moving tubular form comprises an axially compressible jacket with a liquid-retaining annular seal assembly engageable with the tubular form, inlet and discharge means for cooling liquid, and means to releasably support the jacket in an extended configuration.The bath is suitable for cooling tubular extrudates in the production of oriented tubular film.

Abstract: A foam extrusion apparatus and method employs tandem extruders mounted on horizontal rails for movement toward and away from the end of a vacuum chamber which is in the form of an elongated inclined barometric leg. The upper end of the chamber is closed by a substantial bulkhead also supported on rails and held in inclined position to close the end of the chamber when moved thereagainst. A die is positioned on the inside of the bulkhead and aligned with the leg when closed. The extruders are connected to the die through a length of pipe supported through the bulkhead by a stainless steel bellows. The pipe externally of the bulkhead is provided with a circulating jacket for temperature control. The die is adjustable externally of the bulkhead. The extruders, die and bulkhead are movable as a unit or separately toward and away from the chamber to provide access to the die and the interior of the chamber.

Abstract: Substantial and commercially important increases in polypropylene film production rates without adversely affecting film quality are obtained in a tubular water film process. The improvements comprise modifications in the die lip, in the mandrel air (fluid) slot affecting the cooling gas velocity, and in the upper bubble pressure control. The improvements are especially useful to obtain mill rolls 60 to 80 inches wide.

Abstract: A foam extrusion apparatus and method employs an extruder on an upper level extruding foamable extrudate into the upper end of a large elongated barometric leg which extends at a relatively shallow angle into a pool of water at a lower level. A conveyor in the barometric leg extends through a large radius in the pool to guide the extrudate from the pool for further processing. The leg is in the form of an elongated pipeline fabricated from sections and supported on an inclined ramp. Some of the sections are securely anchored to the ramp to resist axial forces when the leg is evacuated. The sections may be reinforced concrete or fabricated reinforced steel of a variety of sectional shapes. Each section is sealed end-to-end so that a vacuum within the leg will draw water from the pool into the leg leaving a vacuum chamber at the upper end of the leg in which the extrudate expands.

Abstract: A polypropylene film which is useful for electrical devices is produced by biaxially stretching an unstretched polypropylene molded article having, on at least one side, a surface layer having .beta.-form crystals, of mean diameter over 7 .mu.m, under such conditions that the stretching temperature at the stretch initiation point is in the range of 145.degree. to 176.degree. C., and the stretch ratio in one direction is less than a factor of 8. The resulting stretched polypropylene film is characterized by excellent mechanical properties, a very dense inner structure, and high air-tightness. The surface of the film has an efficiently roughened, fine, uneven structure containing crater-like patterns or an isotropic network structure and an anisotropic network structure, which is aligned in the extrusion direction.

Abstract: This invention is a process for making a self-welding packaging film by blending at least two ethylene polymers, one of the polymers having a melt flow substantially greater than any of the other polymers in the blend, and thereafter extruding a film from the blend. The film may be self-supporting or it may be an inner layer in a multi-ply film. Preferred ethylene polymers for the blend are the ethylene-vinyl acetate copolymers wherein one copolymer has a melt flow of less than 5.0 and the other has a melt flow greater than 28.0.