Abstract: An annular co-extrusion die for extruding multi-layer tubular plastic film has inner die mandrels stacked one upon another. Each die mandrel has a generally U-shaped cross-section with side walls extending substantially in parallel with the longitudinal axis of the die. The outer surfaces of the die side walls each have a series of helical shaped grooves formed therein. An annular outer die member surrounds the first inner die mandrel and the inner surface of the outer member and the outer surface of the first inner die mandrel form a longitudinally extending annular extrusion passage. Additional longitudinally extending annular extrusion passages are formed between outer and inner surfaces of nesting inner die mandrels.

Abstract: Packaging containing a PVDC barrier layer is manufactured without any significant orientation, with the result that the PVDC harrier layer remains flexible at significantly greater thicknesses than when it is oriented. This increased thickness compensates for the reduced barrier properties resulting from less crystallinity of the PVDC, and hence multilayer plastic tubing can be manufactured in which PVDC is used as a barrier layer instead of aluminum.

Abstract: Stretch film is treated by passing a web of tackifier-containing, unbloomed thin polymer film through a heater so that the web is heated to a temperature sufficient to cause tackifier bloom prior to the web reaching a next stage in an in-line process. Also, a pattern can be applied to a thin polymer film. An oriented web of thin polymer film is passed across at least one heated roller having the pattern engraved thereon to define face regions and relief regions collectively conforming to the pattern. As the web contacts each roller surface, portions of the web positioned over the relief regions receive less heat than portions of the web positioned over the face regions, thereby causing the respective portions of the web to undergo differential, heat-induced shrinkage which imparts the pattern to the thin polymer film.

Abstract: Bags are formed from reclaimed plastic material. Each bag comprises two opposed sheet sections formed substantially entirely of a first polymer class, but also containing impurity particles of a different polymer class. The sheet sections comprise at least two distinct independent layers, with each layer in each sheet section being surface bonded to each adjacent layer in that sheet section. Although discontinuities in each layer resulting from the impurity particles create weak areas and in some cases apertures, the weakened portions of each layer are reinforced by portions of the other layer that are not weakened, since there is a minute likelihood that an impurity particle in one layer will be precisely co-located with an impurity particle in an adjacent layer. Thus, each layer reinforces the other layer to maintain structural integrity of the sheet section and of the bag. Methods for forming such bags are also described.

Abstract: A method of producing a multilayer plastic film from resin starting material includes irradiating a batch of plastic resin material and using irradiated resin from the batch to produce at least one layer of a multilayer plastic film.

Abstract: Stretch film is treated by passing a web of tackifier-containing, unbloomed thin polymer film through a heater so that the web is heated to a temperature sufficient to cause tackifier bloom prior to the web reaching a next stage in an in-line process. Also, a pattern can be applied to a thin polymer film. An oriented web of thin polymer film is passed across at least one heated roller having the pattern engraved thereon to define face regions and relief regions collectively conforming to the pattern. As the web contacts each roller surface, portions of the web positioned over the relief regions receive less heat than portions of the web positioned over the face regions, thereby causing the respective portions of the web to undergo differential, heat-induced shrinkage which imparts the pattern to the thin polymer film.

Abstract: Stretch film is treated by passing a web of tackifier-containing, unbloomed thin polymer film through a heater so that the web is heated to a temperature sufficient to cause tackifier bloom prior to the web reaching a next stage in an in-line process. Also, a pattern can be applied to a thin polymer film. An oriented web of thin polymer film is passed across at least one heated roller having the pattern engraved thereon to define face regions and relief regions collectively conforming to the pattern. As the web contacts each roller surface, portions of the web positioned over the relief regions receive less heat than portions of the web positioned over the face regions, thereby causing the respective portions of the web to undergo differential, heat-induced shrinkage which imparts the pattern to the thin polymer film.

Abstract: Stretch film is treated by passing a web of tackifier-containing, unbloomed thin polymer film through a heater so that the web is heated to a temperature sufficient to cause tackifier bloom prior to the web reaching a next stage in an in-line process. Also, a pattern can be applied to a thin polymer film. An oriented web of thin polymer film is passed across at least one heated roller having the pattern engraved thereon to define face regions and relief regions collectively conforming to the pattern. As the web contacts each roller surface, portions of the web positioned over the relief regions receive less heat than portions of the web positioned over the face regions, thereby causing the respective portions of the web to undergo differential, heat-induced shrinkage which imparts the pattern to the thin polymer film.

Abstract: An air ring for supplying cooling air to a hot extruded plastic film after extrusion from an annular extrusion die has an annular body surrounding the emerging tubular plastic film. The annular body has an annular plenum chamber receiving air from an external source. A circumferentially extending series of separate air passages receives air from the plenum chamber and extends radially inwardly to respective separate orifices adjacent to and surrounding the tubular film. Separate adjustors individually control the air flow from the plenum chamber to respective air passages and associated orifices, whereby air flow from each orifice impinges on a discrete circumferentially extending portion of the tubular film substantially independently of air flow from other orifices. Each adjustor controls air flow to only one orifice. The plenum chamber also supplies air through an annular passage in the annular body to an annular orifice adjacent to and surrounding the tubular film.

Abstract: Gauge distribution apparatus for plastic film has a frame, a rotor mounted on the frame for sequential reversed rotation about a substantially vertical axis, and at least one slot in the rotor through which two lengths of plastic film can pass upwardly with spaced adjacent faces from below the rotor. First and second turning members are mounted on the rotor for receiving a respective length of plastic film and changing the direction of motion thereof from upwardly to horizontally. A series of upstanding circumferentially spaced film engaging members extend around the rotor, each film engaging member having an outer surface for engagement by the plastic film. Third and fourth turning members are mounted on the frame for receiving a respective length of plastic film after it has engaged at least one of the film engaging members and changing its direction of motion from horizontally to vertically.

Abstract: An extrusion die for extruding plastic material as a tubular film has mututally engaging first and second body members which form an annular extrusion orifice therebetween. One of the body members has main feed grooves in a surface thereof adjacent the other body member and extending in a spiral manner relative to the annular extrusion orifice, and one of the body members has supply grooves in a surface thereof adjacent the other body member for receiving plastic material from one or more extruders. Each supply groove has an end portion adjacent but spaced from an initial portion of a main feed groove, whereby plastic material from the extruder or extruders is received by the supply grooves and forced from the end portions thereof along a passage between the body members and into the initial portions of the spiral feed grooves.

Abstract: Stretch plastic film is formed by extruding suitable plastic material from an annular die as a tubular film, forming the extruded film into a bubble with air entrapped therein by collapsing the tubular film at a predetermined distance from the annular die, causing the temperature of the tubular film when collapsed to be sufficiently high to cause opposite sides of the collapsed film to become bonded together to form a blocked two layer film, and stretching the blocked two layer film to reduce its thickness.

Abstract: A method of extruding plastic material in multi-layer form includes: providing an extrusion die having a first body member and a second body member surrounding the first body member and forming an annular passage therebetween which communicates with an annular extrusion orifice, the body members having a series of helical grooves extending around the die and each commencing at a separate location, the separate locations being spaced around a lower portion of the first body member. A single encapsulating unit provides a flow of encapsulated plastic material comprising a first plastic material surrounded by a second plastic material at an outlet thereof. The first body member having a series of cross-holes extending from the encapsulating unit output and each communicating with a respective separate location.

Abstract: A multilayer plastic film has a series of component layers and bonding layers bonding said component layers together, the component layers including an inner hydrolysed ethylene vinyl acetate copolymer (EVOH) layer, an adjacent polyvinylidene chloride (PVDC) layer, and outer layers comprising a polyolefin homopolymer, copolymer or ionomer.

Abstract: An extruder assembly has a gear box drivable by a motor, an output shaft having a main portion extending through the gear box and rotatable by operation of the motor and gear box, and an extruder housing located forwardly of the gear box. The output shaft has a further portion extending forwardly from the main portion and passing into the extruder housing and having a screw configuration therein for feeding plastic material through the housing when the output shaft is rotated. The main portion of the output shaft is axially slidable in the gear box, and the forwardly extending portion has a diameter not greater than the diameter of the main portion whereby the output shaft can be withdrawn from the housing and the gear box by rearward movement therethrough. A retainer is operable to retain the output shaft in an operative position for rotation to feed plastic material through the housing and also to permit the output shaft to be withdrawn by rearward movement when desired.

Abstract: Stretch plastic film is formed by extruding suitable plastic material from an annular die as a tubular film, forming extruded film into a bubble with air entrapped therein by collapsing the tubular film at a predetermined distance from the annular die, and causing the temperature of the tubular film when collapsed to be sufficiently high to cause opposite sides of the collapsed film to become bonded together to form a single layer of film.

Abstract: A multilayer plastic film has at least two inner polyvinylidene chloride (PVDC) layers, outer layers comprising a polyolefin homopolymer, copolymer or ionomer, and bonding layers between the PVDC layers and between the PVDC layers and the outer layers.

Abstract: An apparatus for extruding plastic materials in multilayer tubular form includes an annular extrusion die having an annular extrusion orifice and annular passage for conveying plastic material to the extrusion orifice, the die also having at least one arcuate passage extending at least partly around the annular passage such that the arcuate passage completely surrounds, or where there is more than one arcuate passage in combination completely surround, the annular passage inwardly or outwardly thereof and is or are in communication therewith. A melt stream of plastic material is encapsulated with a different plastic material in a circumferentially continuous manner to produce an encapsulated melt stream, and at least a portion of the encapsulated melt stream is fed to an arcuate passage to cause at least partially encapsulated plastic material to pass into the annular passage with subsequent extrusion in multilayer tubular form from the annular die orifice.

Abstract: A method of controlling lateral wandering of flattened tubular plastic film in gauge distribution apparatus in which gauge distribution is effected by passing a flattened tubular plastic film around at least one turning bar whose position with respect to the film is varied. The method comprises adjusting the position of a turning bar in response to a signal from the sensor which senses the position of one of the side edges of the flattened film before it is wound on a storage roll. When lateral wandering of the flattened tubular film is sensed, the position of the turning bar is varied until the sensor detects that the film has returned to its desired path.

Abstract: An air ring for supplying cooling air to a hot extruded plastic film after the film has been extruded from an annular extrusion die at an elevated temperature has an annular body which surrounds the tubular film after the film has left the extrusion die. The body has a circumferentially extending air passage through which air can be supplied from an external source and which directs cooling air from the passage between the body and the film with a venturi-like effect. A circumferentially extending series of individually operable actuators are each operable to vary the venturi-like effect at its circumferential location and cause the film to become nearer to or further from the body at said location to cause the thickness of the film at said location to decrease or increase.