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 process and apparatus for producing a ribbed pattern on extruded film by differential cooling of the film during its stretching process. The film is extruded through a tubular film die, stretching as it leaves the die. Cooling mechanisms rotate about the tube as it is being extruded to define a large plurality of narrow strips on the melt as it is being extruded. The film is fixed in space to maintain a close proximity to the cooling mechanisms in order to achieve sharply defined ribs. A cross-ribbed pattern can be obtained by counter-rotating the cooling mechanisms. Increased tear strength is imparted to the film without increasing the amount of resin necessary to make the film. Such tube can be formed into high strength film products such as trash bags and the like.

Abstract: A process and apparatus for producing a ribbed pattern on extruded film by differential cooling of the film during its stretching process. The film is extruded through a tubular film die, stretching as it leaves the die. Cooling mechanisms rotate about the tube as it is being extruded to define a large plurality of narrow strips on the melt as it is being extruded. The film is fixed in space to maintain a close proximity to the cooling mechanisms in order to achieve sharply defined ribs. A cross-ribbed pattern can be obtained by counter-rotating the cooling mechanisms. Increased tear strength is imparted to the film without increasing the amount of resin necessary to make the film. Such tube can be formed into high strength film products such as trash bags and the like.

Abstract: The present invention is concerned with the art of manufacturing film from synthetic thermoplastic resinous materials, and more particularly relates to an improved method and apparatus for the manufacture of thermoplastic resinous film in tubular form.

Abstract: A blown film process wherein: the temperature of the film is continually monitored in a select control or target area that is remote from the film frost line; a control of "target temperature" is determined based empirically or otherwise on a given set of companion operating conditions; and a variable film cooling source or supply is regulated to establish the control temperature as an essentially constant or non-variable operating condition. The process is characterized by an essentially stable frost line position and to the extent movement of the frost line can be optically or otherwise observed or sensed, and an appropriate signal derived therefrom, the process can be alternately practiced based on monitoring the position of the frost line, defining a control or "target" frost line position, and regulating a film cooling source responsive to deviances or movement from the control position.

Abstract: Thin plastic tubes are prepared by extruding a heat plastified tube, stretching the tube over a gas bearing having a diameter greater than the diameter of the extruded tube, cooling the surface of the tube adjacent the gas bearing and passing the tube over a cooling mandrel having an outside diameter approximating the diameter of the gas bearing, thereby lowering the temperature of the tube below its heat plastifying temperature.

Abstract: Thin plastic tubes are prepared by extruding a heat plastified tube, stretching the tube over a gas bearing having a diameter greater than the diameter of the extruded tube, cooling the surface of the tube adjacent the gas bearing and passing the tube over a cooling mandrel having an outside diameter approximating the diameter of the gas bearing, thereby lowering the temperature of the tube below its heat plastifying temperature.