NZ556298A - Barrier film products and processes for food packaging - Google Patents

Abstract

A container for a product is formed from an exterior continuous structure providing a peripheral wall (42) and a base (44), and a laminate interior layer (46) having a first layer of plastics material compatible with the product, a substantially oxygen impervious layer and a further layer of weldable plastics material. The exterior structure is made of plastics material welded to the further layer of the interior structure in a moulding process, which also causes the laminate to be formed to provide an overlapping relationship at a junction between the base and the peripheral wall. The plastics material associated with one of the layers of the laminate at the base isl bonded to an adjacent layer of plastics material of the laminate of the peripheral wall in the region of the junction.

Description

10053741302' Patents Form 5 ^5 6 2 9 8 N.Z. No.

NEW ZEALAND Patents Act 1953 COMPLETE SPECIFICATION BARRIER FILM PRODUCTS AND PROCESSES We, NCI Holdings Pty Ltd, an Australian company of 24 Groom Street, Clifton Hill Vic 3068, Australia, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- (Followed by 2) INTELLECTUAL PROPERTY OFFICE OF N.Z. - 3 JUL 2007 RECEIVED BARRIER FILM PRODUCTS AND PROCESSES The present invention relates to packaging particularly food products and other products which need to be kept out of contact with atmospheric oxygen. The invention manifests 5 itself in a packaging method and a container for food adapted to be closed by a lid and a container having a barrier providing substantial oxygen impermeability. Embodiments of the invention maybe applied to packaging a wide range of products requiring an impermeable container.

Various containers and sachets have been proposed for foodstuffs recognising that shelf life requires substantial oxygen impermeability but new and useful alternatives to known proposals are perceived as desirable for the food packaging industry.

In one aspect, the present invention provides a container for a product having (a) an 15 exterior continuous structure providing a peripheral wall and an end wall for forming a base of the container extending transversely to the peripheral wall, and (b) an interior structure provided by a preformed laminate having a product compatible first layer of plastics material, a substantially oxygen impervious layer and a further layer of weldable plastics material, (c) the exterior structure being of plastics material welded to 20 the further layer of the interior structure in a moulding process, which also causes the laminate to be formed to provide an overlapping relationship at a junction between the end wall and the peripheral wall, and (d) the plastics material associated with one of the layers of the laminate at the end wall bonded to an adjacent layer of plastics material of the laminate of the peripheral wall in the region of the junction.

For food storage purposes, the container may use food compatible plastics material such as polypropylene for the first layer of the laminate and'such material is also suitable for use for the further layer of the laminate and the exterior structure.

At least preferred embodiments may be advantageously implemented using injection moulding techniques and in particular known types of injection moulding processes and machines.

Embodiments include such containers which are substantially rigid with the majority of the cross section of the peripheral wall and the base being provided by the exterior structure.

The container may have an open top which may be adapted to be sealed, for example by a peel off foil layer and a security lid may then be placed before shipment and storage. Embodiments of the invention lend themselves to the formation of an integral rim so that there is continuity of oxygen barrier from the interior layer to the closure foil.

Embodiments of the invention also lend themselves to efficient production by applying the interior laminate to a mandrel or male mould part having the slightly tapering body with a transverse end face adapted to define the interior of the bottom wall of the container. The male mould element is inserted into a complementary female mould 15 portion with a cavity defined between the mould portions and into which injection moulding of plastic material takes place under thermal control.

Vacuum, electrostatic of other techniques may be used for holding the laminate portions in position on the male mould part.

In another aspect, the invention consists in a method of forming a container suitable for a product requiring storage substantially without atmospheric oxygen being allowed to contaminate product in the container. The method may comprise (a) establishing in a mould a laminate for forming an interior structure of the container, the laminate having 25 a product compatible first layer of plastics material, a substantially oxygen impervious layer and a further layer of weldable plastics material, the laminate being positioned for forming an interior structure of the container, (b) supplying molten plastics material of a suitable type and temperature to fill a space around the laminate to form an exterior structure of the container including a peripheral wall and an end wall for forming a base 30 of the container extending transversely to the peripheral wall, the interior and exterior structures being welded together, the laminate having an overlapping relationship at a junction between the end wall and the peripheral wall, and the plastics material associated with one of the layers of the laminate at the end wall being bonded to an adjacent layer of plastics material of the laminate of the peripheral wall in the region of the junctioa The method may be applied using injection moulding in a mould having a male portion onto which the laminate is applied to provide an interior layer of the container in respect of the base and the peripheral wall and the mould has a female part into which the male mould is inserted to defined a gap for receiving molten plastics material.

The method may be applied using polypropylene as the plastics material with the first layer and the further layer of the laminate also comprising polypropylene. The oxygen impervious layer may be metallic.

By way of example the invention will be described in embodiments with reference to 15 the accompanying drawings of which: Figure 1 comprises a plan view of laminate comprising portions for a peripheral wall and a base for a container being an embodiment of the invention; Figure 2 is an alternative to the arrangement of Figure 1 for forming a generally cylindrical container and showing the interior structure laminate ready to be applied and folded into position; Figure 3A schematically illustrates in a cross-sectional view an injection moulding 25 arrangement forming containers embodying the invention; Figure 3B is a view of detail B from Figure 3A; Figure 3C is a view on greatly enlarged scale of portion C of Figure 1 showing the 30 mould when assembled with the laminate in position before injection moulding; Figure 4A illustrates the injection moulding arrangement for the arrangement of Figures 3A to 3C; Figure 4B is a view on the large scale of portion B of Figure 4A; Figure 4C is a view on a greatly enlarged scale of portion C of Figure 4 A showing that molten plastics material being injected and forming the overlapping layers of the interior laminate to weld to one another; Figure 5 A is a view of injection moulded container embodying the invention and 10 provided with a top closure; Figure 5B is a an enlarged view of detail B in Figure 5A when the container is closed with a foil and cap; Figure 5C is a view of detail C of Figure 5 A showing the provision of flexible foil top closure; and Figure 6 is a schematic representation showing the supply of laminate portions for a circular end wall and a tapered peripheral wall applied to a male portion of an injection 20 moulding machine and for use informing a product described with reference to the other drawings.

Figure 1 shows in plan view an arcuate laminate element 10 and a disc shaped laminate element 12 respectively for forming the peripheral wall and the base layer on the inside 25 of a formed container and having respective portions 14 and 16 for forming an overlap in a moulding process as described further below.

Each element is formed of laminate comprising outer layers of polypropylene or other suitable weldable plastic material and a thin inner layer of metal foil such as aluminium 30 which forms a substantially impervious oxygen barrier. The plastics material is chosen to be compatible with the product to be contained in the container and typically if this is a food product polypropylene is an excellent choice.

Figure 2 shows an alternative arrangement of an integral laminate 18 having respective overlap portions 20 and 22, otherwise the laminate being as described with reference to figure 1.

Figure 3A illustrate an injection mould having a male portion or core 24 and a female part 26 shown in the drawing when assembled for an injection moulding process, the female portion having an injection point 28 in the base for injecting molten plastics into the container shaped cavity 30 defined between mould portions.

Figure 3B shows detail B on an enlarged scale wherein the mould is being assembled for after positioning the wall laminate 10 around the elongate peripheral surface of the core 24 and the disc shaped laminate portion 12 has been placed on the transverse end face of the core 24 with the overlap portion 16 extending, as shown, across the mould 15 cavity.

Figure 3C shows this configuration in detail showing each laminate comprising outer plastic layers 11A and 1 IB and a thin foil layer of metal such as aluminium 11C. Although not shown in figure 3C, an overlap is established along the laminate at one 20 location around the structure.

Figure 4A diagrammatically illustrates the mould of figure 3A when injection moulding has occurred with an illustration of the flow of the injected plastics material 32 into the cavity 30.

The detail of the bottom cavity is shown in figure 4B.

Figure 4C shows detail C on an enlarged scale from which it will be seen that the pressure of the mould and plastics material 32 presses the overlap portion 16 at the 30 laminate base against the confronting surface of the outer layer of the laminate portion 10 and, due to the thermal affects of the mould and plastic, welding occurs between the contacting plastics layers on the inside of the overlap layer 16 and on the outside of the laminate portion 10.

Figure 5A illustrates the resulting container 40 ejected from the mould with an integral structure comprising the exterior peripheral wall 42 and base 44 with, on the interior, 5 although not shown in figure 5A, the overlapping laminate interior layer 46.

As shown in figure 5C being detail C from figure 5A, a rim 48 is formed in the moulding to provide rigidity and an arrangement to retain a closure cap. A metal flexible foil 50 is secured across the top of the container with a suitable adhesive where 10 it contacts the top portion 52 of the inner laminate structure 46 at the top of the rim 48.

As shown in figure 5B and detail B, a cap 54 has a depending skirt 56 with an undercut to form an inwardly extending bead 58 that snap fits over the end of the rim to securely close the container and protect the flexible foil from damage during storage and transit.

Figure 6 illustrates schematically how core 24 is mounted on a base 25 which is placable in an injection moulding machine. At a preliminary station the core 24 is positioned for receiving an arcuate laminate element 10 which is wrapped around the core with an overlap 11A as indicated and a disc shaped laminate element 12 is supplied 20 from a separate box supply to be positioned on the end face of the core with the periphery of the element 16 extending radially outwardly from the end of the core and ready for insertion into the male part to be deflected to the displaced position shown in figure 3C.

Suitable techniques for holding the laminate elements on the core include the use of vacuum systems, and electro static arrangements.

Claims (12)

WHAT WE CLAIM IS:

1. A container for a product having (a) an exterior continuous structure providing a peripheral wall and an end wall for forming a base of the container extending 5 transversely to the peripheral wall, and (b) an interior structure provided by a preformed laminate having a first layer of plastics material compatible with the product, a substantially oxygen impervious layer and a further layer of weldable plastics material, (c) the exterior structure being of plastics material welded to the further layer of the interior structure in a moulding process, which also causes the laminate to be formed to 10 provide an overlapping relationship at a junction between the end wall and the peripheral wall, and (d) the plastics material associated with one of the layers of the laminate at the end wall bonded to an adjacent layer of plastics material of the laminate of the peripheral wall in the region of the junction. 15

2. A container as claimed in claim 1 and wherein the layer of the laminate to contact the product is food compatible.

3. A container as claimed in claim 2, wherein both the first layer and the further layer of the laminate are of a food compatible plastics material and substantially the 20 same material is used for the exterior structure, the container being formed by injection moulding.

4. A container as claimed in any one of the preceding claims, wherein the exterior structure provides substantial rigidity to the container and an opening of the container is 25 adapted to receive a closure element which is substantially impermeable to atmospheric oxygen.

5. A container as claimed in any one of the preceding claims, wherein either or both of the first layer and the further layer are of polypropylene, and the oxygen 30 impervious layer is of thin metal.

6. A container as claimed in any one of the preceding claims, wherein the -9- container is fonned by injection moulding of the exterior structure around the interior structure.

7. A product in a container as claimed in any one of the preceding claims and 5 wherein the container protects the product from oxygen of the atmosphere and the container is closed with a foil closure element.

8. A method of forming a container suitable for a product requiring storage without atmospheric oxygen being allowed to contact product in the container, the 10 method comprising (a) establishing in a mould a laminate for forming an interior structure of the container, the laminate having first layer of plastics material compatible with the product to be received in the container, a substantially oxygen impervious layer and a further layer of weldable plastics material, the laminate being positioned for forming an interior structure of the container, (b) supplying molten plastics material of a 15 suitable type and temperature to fill a space around the laminate to form an exterior structure of the container including a peripheral wall and an end wall for forming a base of the container extending transversely to the peripheral wall, the interior and exterior structures being welded together, the laminate having an overlapping relationship at a junction between the end wall and the peripheral wall, and the plastics material 20 associated with one of the layers of the laminate at the end wall being bonded to an adjacent layer of plastics material of the laminate of the peripheral wall in the region of the junction.

9. A method as claimed in claim 8, wherein the laminate is positioned on a 25 mandrel of the mould using vacuum or electrostatic force, the mandrel having a tapering form.

10. A container substantially as herein described with reference to the accompanying drawings. 30

11. A method of forming a container substantially as herein described with reference to the accompanying drawings. » . -10-

12. A method of food packaging comprising taking a container as claimed in any one of claims 1 to 6 or 10, filling the container with the food, and applying a sealing closure to an open end of the container through which it has been filled. NCI HOLDINGS PTY LTD By Their Attorneys HENRY HUGHES Per: 5"—^ INTELLECTUAL PROPERTY OFFICE OF N.2. 2 6 SEP 2007 I RECEIVED