Abstract: A tubular, biaxially stretch-oriented packaging film, in particular a sausage casing, comprising a polymer mixture which comprises an aliphatic polyamide, a polyterephthalic acid ester, an aromatic polyamide comprising branched aliphatic diamines having at least 7 carbon atoms and aromatic dicarboxylic acids, or aromatic diamines and aliphatic dicarboxylic acids having 5 to 11 carbon atoms and a dye. The weight amount of the aromatic polyamide is preferably equal to, and particularly preferably greater than, the weight amount of dye. A masterbatch suitable for producing the film is also disclosed. With particular advantage, the film having the above described composition can be dyed deep black or brilliant red.

Abstract: A seamless parison extruded from an extruder via an annular die, passes through a calibrator and coaxially surrounds a probe pipe, which is made to extend through the annular die beyond the calibrator. On the probe pipe there is mounted a sealing element. Ahead of the sealing element, a pressure equal to atmospheric pressure prevails inside the tube and, after the sealing element, a higher pressure than atmospheric pressure prevails. The pressurization is achieved in that a second belt take-off folds together the tube, so that the compressed air fed in through the probe pipe causes a higher tube internal pressure, since the sealing element bears in a sealing manner against the inside of the tube. As a result, a substantial pressure separation is effected at the point of the sealing element.

Abstract: A tubular packaging film, in particular a sausage casing for scalded and cooked sausages. The polymer mixture of said film has, on a 100 parts polymer basis, from 30 to 90 parts by weight homopolyamide or copolyamide, and from 70 to 10 parts polyterephthalic acid ester and/or copolyester of terephthalic and isophthalic acid units. The polyester is formed with an aliphatic or alicyclic diol. The film also optionally contains additives such as silicone oils which improve slip properties.

Abstract: Disclosed is a multi-layer tubular packaging material having two or more layers, comprising at least one first layer of a polymer comprising a linear polyamide and at least one second layer of a polymer comprising a linear polyamide containing from about 2 to 40 percent by weight of a hydrophilic substance compatible with the polyamide, e.g., polyvinyl alcohol.

Abstract: Disclosed is a multi-layer film having two or more layers, comprising at least one first layer of a polymer comprising a linear polyamide, and at least one second layer of a polymer comprising a linear polyamide containing from about 2 to 40 percent by weight of a hydrophilic substance compatible with the polyamide, such as polyvinyl alcohol.

Abstract: This invention relates to a biaxially stretched and longitudinally afterstretched thin-walled tubular film of polyethylene terephthalate having a tensile stress of 40 to 60 kg/mm.sup.2 and a tear resistance of 40 to 70 kg/mm.sup.2 in the longitudinal direction, and an elongation at break of 350 to 800% in the transverse direction. The invention also relates to a process for the production of the film.

Abstract: This invention relates to a process for the manufacture of a plastic tube suitable for use as a sausage casing, which comprises extruding a crystalline thermoplastic material at a temperature above its crystalline melting point through an annular die of non-uniform cross-section, to produce a tube any cross-section of which varies continuously from a maximum to a minimum, the positions of the minimum and maximum thickness being diametrically opposed, the maximum being 1.3 to 3.0 times as thick as the minimum, cooling the tube to below its crystalline melting point, biaxially orienting the tube, and longitudinally stretching the biaxially oriented tube under conditions such that the temperature of the portion of the tube of maximum thickness is greater than that of the portion of the tube of minimum thickness. The invention also relates to the tube so produced.