The present invention relates to an external cooling system for a molten film tube produced by a blown film tubular extrusion process, comprised of one or more enclosures with one or more respective cavities that directly receive a portion of cooling gas emanating from one or more associated cooling elements. Each enclosure includes a port containing a variable exhaust device and optional flow buffer, acting to maintain a pressure differential between the cavity and an adjacent inside volume of the molten film tube, adjustable to optimize molten film tube stability cooling element efficiency and spaced apart dimension between cooling elements. Significant increases in production speeds are achieved with improved film quality over an increased range of tubular film sizes, down to a minimum size which occurs when operating at zero internal to molten film tube pressure.

The present invention relates to an external cooling system for a molten film tube produced by a blown film tubular extrusion process, comprised of one or more enclosures with one or more respective cavities that directly receive a portion of cooling gas emanating from one or more associated cooling elements. Each enclosure includes a port containing a variable exhaust device and optional flow buffer, acting to maintain a pressure differential between the cavity and an adjacent inside volume of the molten film tube, adjustable to optimize molten film tube stability cooling element efficiency and spaced apart dimension between cooling elements. Additionally, at least one cooling element is provided, comprised of a divergent cooling element with a divergent cooling interface containing a cooling gas deflector spaced adjacent to the molten film tube and providing an expelled cooling gas.

The present invention relates to an external cooling system for a molten film tube produced by a blown film tubular extrusion process, comprised of a divergent cooling element with a divergent cooling interface containing a cooling gas deflector spaced adjacent to the molten film tube and providing an expelled cooling gas (i) in a path opposing the flow of the molten film tube toward a first exit gap and (ii) in a path with the flow of the molten film tube toward a second exit gap. A minimum gap between the divergent cooling interface and the molten film tube occurs at the first exit gap and/or the second exit gap. Advantageously, the divergent cooling interface is provided with one or more compound angles to maximize stability and cooling efficiency. Additionally, multiple cooling elements can preferably be arranged in a stackable configuration to achieve higher throughput rates. Operation is characterized by improved film holding forces without the presence of high noise levels or detrimental vibration, flutter, and drag. Additionally, employing simplified single air delivery channels, and a stackable design, significantly reduces complexity and manufacturing costs.

The present invention relates to an external cooling system for a molten film tube produced by a blown film tubular extrusion process, comprised of one or more enclosures with one or more respective cavities that directly receive a portion of cooling gas emanating from one or more associated cooling elements. Each enclosure includes a port containing a variable exhaust device and optional flow buffer, acting to maintain a pressure differential between the cavity and an adjacent inside volume of the molten film tube, adjustable to optimize molten film tube stability cooling element efficiency and spaced apart dimension between cooling elements. Additionally, at least one cooling element is provided, comprised of a divergent cooling element with a divergent cooling interface containing a cooling gas deflector spaced adjacent to the molten film tube and providing an expelled cooling gas.

A micro-voided film comprising high density polyethylene having a molecular weight of at least about 200,000, and low aspect ratio filler having a mean particle size from about 1 to about 25 microns. The film has a thickness of from about 0.1 to about 20 mils and a void fraction of from about 0.60 to about 0.75. The micro-voided film is made by a process comprising extruding the composition into a film having a thickness of from about 20 to about 200 mils, and orienting the extruded film using a high stalk, blown film process. The process produces a stabilized high stalk for increasing the production rate of blown, high molecular weight polyethylene, while increasing the film's physical and mechanical properties. The high stalk can be stabilized by application of high velocity, low volume flow rate of air over the interior and exterior surfaces of the extruded film.

A method for producing a biaxially oriented tube from thermoplastic material, wherein a tube in preform condition is extruded from thermoplastic material and is subjected to a temperature conditioning. Use is made of an expansion device and of a drawing device which is arranged downstream of the expansion device. The expansion device includes a non-deformable expansion part and a run-on part located upstream of the expansion part and having an upstream sealing member. The expansion device further includes a first gas discharge duct having one or more first inlet ports in the exterior surface of the expansion device, a first inlet port being open or closed or partly closed dependent on whether or not the first inlet port is covered and closed, or partly closed, by the tube.

A method for producing a biaxially oriented tube from thermoplastic material, wherein a tube in preform condition is extruded from thermoplastic material and is subjected to a temperature conditioning. Use is made of an expansion device and of a drawing device which is arranged downstream of the expansion device. The expansion device includes a non-deformable expansion part and a run-on part located upstream of the expansion part and having an upstream sealing member. The expansion device further includes a first gas discharge duct having one or more first inlet ports in the exterior surface of the expansion device, a first inlet port being open or closed or partly closed dependent on whether or not the first inlet port is covered and closed, or partly closed, by the tube.

A method of forming a blown film comprising extruding a molten composition through a die opening to form a film; wherein the molten composition comprises at least one polyethylene and within the range from 0.10 wt % to 10 wt % of a cyclic-diene terpolymer by weight of the composition; causing the film to progress in a direction away from the die opening; cooling the film at a distance from the die opening, the distance adjusted to effect the properties of the film; and isolating a blown film therefrom.

A method for producing a biaxially oriented tube from thermoplastic material, wherein a tube in preform condition is extruded from thermoplastic material and is subjected to a temperature conditioning. Use is made of an expansion device and of a drawing device which is arranged downstream of the expansion device. The expansion device includes a non-deformable expansion part and a run-on part located upstream of the non-deformable expansion part and having an upstream sealing member. The expansion device further includes a first gas discharge duct having one or more first inlet ports in the exterior surface of the expansion device, a first inlet port being open or closed or partly closed dependent on whether or not the first inlet port is covered and closed, or partly closed, by the tube.

A method for producing a biaxially oriented tube from thermoplastic material, wherein a tube in preform condition is extruded from thermoplastic material and is subjected to a temperature conditioning. Use is made of an expansion device and of a drawing device which is arranged downstream of the expansion device. The expansion device includes a non-deformable expansion part and a run-on part located upstream of the non-deformable expansion part and having an upstream sealing member. The expansion device further includes a first gas discharge duct having one or more first inlet ports in the exterior surface of the expansion device, a first inlet port being open or closed or partly closed dependent on whether or not the first inlet port is covered and closed, or partly closed, by the tube.