Dimensionally stable thermoplastic tubular articles

Abstract From the Canadian patent

For heat-setting tubular articles (such as can bodies) of an at least partly biaxially oriented crystallisable 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 mandre1 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 into the interior of the mandrel above the, temperature to which it is to be heat-set (at least 60°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 …