The present invention relates to a process for producing a polymer film (P) comprising a polyamide composition (PC) by extruding the polyamide composition (PC) through an annular die and then stretching the tube thus obtained by blowing in air. The present invention further relates to the polymer film (P) obtainable by the process of the invention and to a process for packaging foodstuffs with the polymer film (P).

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. 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 thickness profile of a film tube manufactured using a film blowing process is regulated using a control system consisting of segmented control zones and at least at two measuring units for the film thickness such that the specified target film thickness profile exhibits deviations from a uniform film thickness in the form of one or two thin spots opposite each other, which serve to compensate for film thickness changes across the film width which occur during the monoaxial orientation in machine direction so that a film web is produced as a result of orientation whose thickness profile has as few deviations as possible from the target thickness across the entire width of the film web, the final film should exhibit a thickness profile where the thickness increase from the middle of the film to the edges is as minor as possible and the flatness of the film is improved.

The thickness profile of a film tube manufactured using a film blowing process is regulated using a control system consisting of segmented control zones and at least at two measuring units for the film thickness such that the specified target film thickness profile exhibits deviations from a uniform film thickness in the form of one or two thin spots opposite each other, which serve to compensate for film thickness changes across the film width which occur during the monoaxial orientation in machine direction so that a film web is produced as a result of orientation whose thickness profile has as few deviations as possible from the target thickness across the entire width of the film web, the final film should exhibit a thickness profile where the thickness increase from the middle of the film to the edges is as minor as possible and the flatness of the film is improved.

A machine direction oriented film comprising a multimodal copolymer of ethylene and at least two alpha-olefin-comonomers having: a) a density of from 906 to 925 kg/m.sup.3 determined according to ISO 1183, b) an MFR.sub.21 of 10-200 g/10 min determined according to ISO1133, wherein the multimodal copolymer of ethylene comprises c) a first copolymer of ethylene and a first alpha-olefin comonomer having 4 to 10 carbon atoms; and d) a second copolymer of ethylene having an alpha-olefin comonomer different from the first copolymer, said second alpha-olefin comonomer having 6 to 10 carbon atoms.

A machine direction oriented film comprising a multimodal copolymer of ethylene and at least two alpha-olefin-comonomers having: a) a density of from 906 to 925 kg/m.sup.3 determined according to ISO 1183, b) an MFR.sub.21 of 10-200 g/10 min determined according to ISO1133, wherein the multimodal copolymer of ethylene comprises c) a first copolymer of ethylene and a first alpha-olefin comonomer having 4 to 10 carbon atoms; and d) a second copolymer of ethylene having an alpha-olefin comonomer different from the first copolymer, said second alpha-olefin comonomer having 6 to 10 carbon atoms.

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.

Aspects of the disclosure relate to envelopes for aerial vehicle. The aerial vehicle may include an envelope including a plurality of gores. The aerial vehicle may also include a seal arranged between a pair of the plurality of gores, the seal including six layers of envelope material heat-sealed together.

The invention relates to a monitoring method for monitoring a film bubble (FB) in a discharge region (112) downstream of a discharge nozzle (110) of a blown film device (100), comprising the following steps: optically detecting at least one contour parameter (KP) of a film contour (FK) of the film bubble (FB) in the discharge region (112), comparing the at least one detected contour parameter (KP) with a specific preset value (VW), determining a contour deviation (KA) between the at least one detected contour parameter (KP) and the specific preset value (VW), outputting the contour deviation (KA) as monitoring result (UE).