Metal Box Public Limited Company

Mb Group Plc Engineering Company

Alan J Maskell

Graham Martin Gossedge

Terence A Benge

John Moore

John Chapman

A container comprising a body with a rim (6) of which at least the upper surface is of a first plastics material, and a flexible closure (8) of which at least the under surface is of a second plastics material different from the first, the body and closure being attached together by a heat seal formed between the said surfaces thereof, wherein the heat seal includes radially inner and radially outer ears (18,16) formed during the heat sealing operation by heat and pressure, each ear having a core (22,20) which is formed of the first plastics material and is joined integrally to the rim by a thin root (34,32), and an envelope (26,28) which is formed of the second plastics material integrally with the closure and which envelops the core and tapers in beneath the core to a position adjacent to the thin root of the core, both ears lying on the top of the rim around at least a substantial part of the container periphery, the closure having a free portion (10) located outside the heat seal for grasping by the user, and the closure and both ears being manually peelable together away from the rim by use of the free portion.

Container with peelable seal, and method for making the same

A retortable, hydraulically solid, sealed package (10) containing a liquid or semi-liquid food product (24) comprises a thermoplastics container (12) formed by a thermo-forming process and a heat-shrinkable thermoplastics closure diaphragm (20). The closure diaphragm is heat-sealed to a rim (18) of the container after the headspace above the product has been evacuated, and is subsequently subjected to external pressure so as to be non-elastically stretched and made to lie wholly in contact with the enclosed product. When retorted (e.g. for sterilization) the package suffers no visible deformation of the container (12), despite the considerable volume shrinkage of the container which may occur. The loss of volume caused by this volume shrinkage is accommodated by a reduction in the concavity of the diaphragm (20) caused by a corresponding heat-induced shrinkage of the diaphragm material. The diaphragm continues to exhibit a pleasing, smooth or smoothly curving surface, and the retorted package has a consumer-acceptable appearance.

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Harwell, United Kingdom

Alan J Maskell