The Linpac Patent
4.Linpac’s patent is UK Patent No. 2 478 028 (‘the Linpac Patent’). It has a priority date of 8 January 2010. The specification introduces the invention claimed by stating that it was known to use plastic containers to package, store, transport and display fresh food. Such containers are commonly made of polyethylene terephthalate (PET). The specification states that it is difficult to attach a lidding film (i.e. a lid in the form of a plastic film) to PET and that sealing is sensitive to contamination. 5.A known way of dealing with this problem was to make the containers from a threelayer material consisting of PET, an intermediate layer of ethylene vinyl acetate (EVA) and a layer of polyethylene (PE). The lidding film readily attaches to PE, which provides the uppermost surface of the container and so facilitates easy sealing. However, containers made from PET/EVA/PE are less clear than those made from PET, they are more expensive, less recyclable and less easy to manufacture. A particular problem is that the manufacturing process gives rise to ‘skeletal waste’ – the remaining parts of sheets of the material from which the containers are cut. This cannot be recycled to make clear containers and so becomes an unused environmental hazard. 6.The specification explains that the solution to the foregoing problems is to use only PET, or other suitable material which is transparent and recyclable, and to introduce into the design of the container a ‘peripheral flange’, i.e a horizontal surface extending around the upper periphery of the container. A layer of adhesive is applied to the flange. The lidding film is then pressed on to the flange, sealing the container. 7.Figure 3 of the Linpac Patent shows a perspective view of a container made according to the invention. The black line around the rim is the adhesive on the top of the peripheral flange:
8.Linpac has applied to amend the patent. At the trial attention was directed to claims 1 and 5 together with 6 and 7 as proposed to be amended:
1. A container comprising a base and a continuous side wall extending substantially perpendicular to the base with a peripheral flange formed along the upper, in use, edge of the continuous side wall, wherein the base and the continuous side wall consist essentially of polyethylene terephthalate (PET) wherein a layer of adhesive is located on an upper, in use, surface of the peripheral flange and said layer of adhesive does not extend onto the vertical, in use, surfaces of the continuous side wall and does not extend onto the base wherein the container further comprises a lidding film which may be sealed to the peripheral flange to create a sealed space between the base, continuous side wall and lidding film; and wherein the lidding film is a multi-layer film comprising a seal layer and the seal layer comprises polypropylene (PP) and/or PE. 5.
A container according to any preceding claim, wherein the thickness of the layer of adhesive is from 20µm to 100µm, preferably 50µm. 6.
A container according to any preceding claim, further comprising at least one denesting recess located in a denesting area, wherein the denesting area is relieved relative to the upper surface of the peripheral flange so that the distance between the upper surface of the relieved area and the base of the tray is shorter than the distance between the upper surface of the flange and the base, and the denesting area is devoid of adhesive. 7.
A container according to claim 6, wherein the relieved denesting area is located at the corners of the tray.