Metal Box Corporation

Cmb Foodcan Plc

Carnaudmetalbox Plc

Cmb Packaging (uk) Limited

Melvin Edward Robinson

James William Nicholas

Rickworth Folland

Michael Alexander Cochran

David A Dick

Glyn Staines

Peter E Butcher

John F Adams

The present invention provides a wall for a package, which wall comprises, or includes a layer comprising, a composition comprising a polymer and capable of scavenging oxygen through the metal-catalyzed oxidation of an oxidizable organic component thereof. The oxidizable organic component is preferably itself a polymer, and may be the only polymer in the composition. Preferred compositions include a blend of 96% polyethylene terephthalate and 4% poly (m-xylyleneadipamide) containing 200 ppm cobalt as catalyst, with good permeance-versus-time performance (3) when formed into a bottle.

Packaging

The present invention provides a wall for a package, which wall comprises, or includes a layer comprising, a composition comprising a polymer and capable of scavenging oxygen through the metal-catalysed oxidation of an oxidisable organic component thereof. The oxidisable organic component is preferably itself a polymer, and may be the only polymer in the composition. Preferred compositions include a blend of 96% polyethylene terephthalate and 4% poly (m-xylyleneadipamide) containing 200 ppm cobalt as catalyst, with good permeance-versus-time performance (3) when formed into a bottle.

A process for the production of a wall for a package including producing a preform of the wall and stretching the preform of the wall where the preform includes a layer containing a polymer and having oxygen-scavenging properties. The preform and the stretching ratios applied are chosen (i) so that the time (t.sub.I) which the permeance of the wall for oxygen would take to rise to 1/5 of the value it would have in the absence of oxygen scavenging would be at least 10 days and (ii) if the preform were stretched at that time (t.sub.I) after the preform were produced, the time (t.sub.D) which the permeance of the wall for oxygen would take to rise 1/5 of the value it would have in the absence of scavenging would be at least 1/4 of the time (t.sub.I). The time between completion of step (A) and the commencement of step (B) is at least 10 days.

Process for production of a wall for a package

A food container comprising an open-ended cylindrical body which is made of a crystallizable polyethylene terephthalate material, and end closures at each end of the body forming with the body a closed container, the body material being biaxially oriented and the container body having been head-set, while restrained against radial or axial shrinkage, at a temperature between about 180.degree. C. and about 240.degree. C., whereby the container is able to withstand hot-filling, pasteurization or sterilization temperatures of up to about 120.degree. C. without undergoing shrinkage of its linear dimensions by more than 3%.

Dimensionally stable thermoplastic tubular articles

For heat-setting tubular articles (such as can bodies) of an at least partly biaxially oriented crystallizable polymer, preferably a saturated linear polyester such as polyethylene terephthalate, e.g. for thermally processable food containers, a tube of the polymer is fitted over a mandrel and clamped at its ends to the mandrel at a temperature below the glass transition temperature of the polymer. The tube is then heated, e.g. by inserting a heater 28 into the interior of the mandrel, above the temperature to which it is to be heat-set (at least 60.degree. C. above for PET) whereupon it shrinks into contact with the mandrel but is restrained from axial or further radial shrinkage. The tube and mandrel are cooled to below the heat-set temperature and the tube may then be cut into can body sections by knives engaging in circumferential grooves. Contact between the tube and mandrel is released, e.g. by forcing compressed air out through small holes in the mandrel surface to allow the tube and mandrel to be separated. Tubular bodies with one closed end can be heat-set on a mandrel with a correspondingly shaped end.

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Wantage, United Kingdom

Melvin Edward Robinson