FIELD OF THE INVENTION THIS INVENTION relates to a casing for a paste.

BACKGROUND TO THE INVENTION

Casings for pastes are manufactured using films of many different types of synthetic plastics material. The films that are chosen depend on the properties that are required. When edible products are in the casing, gas barrier properties are usually required to prevent oxygen penetration into the casing. Likewise water vapour barrier properties are required to prevent transfer of water to and from the paste.

In addition to their barrier properties, the films must be compatible with one another in the sense that it must be possible to laminate them together and then secure the longitudinally extending edges of the films together by heat sealing to form the requisite cylindrical casing.

The use of casings comprising different films laminated together not only enables the requisite properties to be obtained, but also enables printing to be applied to one of the surfaces of one of the films which is then covered by another film which is transparent. The printing is thus visible but not exposed and cannot be scuffed during processing, handling and transport. The problem with scuffed casings is that they look old and customer resistance is encountered.

The present invention has as its main object the provision of a casing with the desired gas and water barrier properties which can be formed with a heat sealed seam. BRIEF DESCRIPTION OF THE INVENTION

According to the present invention there is provided a cylindrical casing for paste which comprises two films of synthetic plastics material laminated together, one film being of polyamide and the other film being of polyethylene and there being an overlap seal where the polyamide is heat sealed to the polyethylene.

The polyamide can be shrinkable polyamide.

The polyethylene can be low density polyelthylene, linear low density polyethylene, high density polyethylene or metallocene.

Preferably the polyethylene is a blend of linear low density polyethylene and high density polyethylene with the linear low density polyethylene predominating. BRIEF DESCRIPTION OF THE DRAWINGS

For the better understanding of the present invention reference will now be made, by way of example, to the accompanying drawings in which the single Figure is a diagrammatic representation of the heat sealed overlap seam of a tubular casing. DETAILED DESCRIPTION OF THE DRAWINGS

The single Figure diagrammatically illustrates the overlap seal 10 of a tubular casing, the chain dotted line indicating the fact that the portion illustrated is part of a cylindrical product. The outer film 12 is of a shrinkable polyamide which will hereinafter simply be referred to as "nylon". It is laminated to an inner film 14 which is low density polyethylene, linear low density polyethylene, high density polyethylene, metallocene or a blend of these forms of polyethylene. A preferred blend for the inner film 14 comprises a

preponderance of linear low-density polyethylene and a smaller portion of high-density polyethylene. The blend can also include pigment, preferably white pigment, anti-block and other constituents to obtain a casing having the desired properties.

The cylindrical casing is formed by overlapping the edges of an elongate web and then heat sealing the inner surface of the polyethylene constituting the inner film to the outer surface of the nylon which comprises the outer film. Alternatively the nylon can comprise the inner film and its inner surface can be heat sealed to the outer surface constituted by the polyethylene. It has been found experimentally that the two films can, at the overlapped edge zones, successfully be heat sealed to one without degrading the polyethylene whilst still reaching a temperature sufficient to fuse the nylon and the polyethylene. The resultant seam of the casing, after the casing has been briefly scalded to shrink it onto the contained paste, has an appearance which is of acceptable quality.