Hoechst Aktiengesellschaft

Hans Strutzel

Siegfried Janocha

Klaus Hoheisel

Detlef Gneuss

Guenther Crass

Karl Stenger

Ludwig Klenk

Peter Wink

Wolfgang Meintzschel

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.

Packaging film, in particular a sausage casing, based on polyamide

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. In a first heating chamber, the tube is heated to the stretching temperature and is transported by a second belt take-off at a stretching speed, increased relative to the take-off speed of the first belt take-off, to a second heating chamber, in which a heat setting of the tube takes place. From the heating chamber, the tube is transported onward at the same, greater or lower speed than the stretching speed by a third belt take-off and wound up by a deflection roller onto a wind-up roller.

Process and apparatus for the production of an extruded, stretched,

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.

Polyamide-based tubular packaging film

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.

Thermoplastic multi-layer film

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.

Tubular packaging material, preferably for use as a sausage casing

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.

Tubular film of polyethylene terephthalate and process for the

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.

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Wiesbaden, Germany

Hans Strutzel