GB2450872A

GB2450872A - Food packaging container comprising moulded fibre

Info

Publication number: GB2450872A
Application number: GB0713230A
Authority: GB
Inventors: Gary Orsman; Giorgio Damiano
Original assignee: St Neots Packaging Ltd
Current assignee: St Neots Packaging Ltd
Priority date: 2007-07-07
Filing date: 2007-07-07
Publication date: 2009-01-14
Anticipated expiration: 2027-07-07
Also published as: GB2450872B; GB0713230D0

Abstract

The material of an article of packaging for a foodstuff comprises moulded fibre, the inner surface of the article being proximal to the packaged foodstuff, wherein the inner surface is coated with a barrier coating which reduces the absorption of liquid water and/or water vapour by the moulded fibre packaging. The moulded fibre comprises non-wood paper pulp from sources such as sugar cane and reed. The coating may comprise polyethylene, polyester, PMMC or a water-based lacquer and may be applied by spraying. The depth of the article at its deepest point may be at least 70 mm. The article may be configured, as shown, to package triangular cut sandwiches. The article may have a lid heat-sealed thereon and may comprise a transparent window portion.

Description

1 2450872 Title: Improvements in or Relating to Food Packaging

Field of the Invention

The present invention relates to an improved article of packaging for a foodstuff, especially packaging for triangular-shaped sandwiches, and a method of making the packaging.

Background of the Invention

Many materials have been used for packaging foodstuffs. Synthetic plastics materials have been widely used as they are light, strong and can readily be used to make hermetically sealed packages. However, these materials are not biodegradable and not readily recyclable.

One material which has been used recently for packaging foodstuffs is "moulded fibre".

This comprises non-wood paper pulp which is processed to form a homogeneous fluid mass. The mass is then moulded, pressurized and dried to form containers of the desired shape, which are very light and strong. The non-wood fibres are typically virgin pulp from renewable and sustainable sources, such as sugar cane and reed. As a result, the packaging is largely biodegradable, recyclable, sustainable, environmentally acceptable and cheap, with little variation in price from year to year.

When used for packaging foods, the moulded fibre material is formed with an integral moisture-resistant material incorporated into the packaging. This serves the purpose of reducing the permeability of the packaging, which would otherwise be highly absorbent, and prevents the leakage of liquids through the container.

Despite being a very useful packaging material for foodstuffs, moulded fibre suffers from several disadvantages, some of which have not previously been recognised by those skilled in the art. The present invention seeks, in various embodiments, to ameliorate, reduce or overcome one or more of these disadvantages. In particular the present invention aims to provide a carton for triangular-shaped sandwiches, the carton being substantially air-tight (thus conferring long shelf-life and freshness) and substantially biodegradable.

Summary of the Invention

A first problem which has been identified by the present inventors, is that the moisture-resistant component incorporated into moulded fibre packaging is surprisingly not sufficient to prevent the packaging from absorbing quite large amounts of water from the packaged foodstuff, which can cause the packaged foodstuff to become stale within 24 hours, despite the packaging being hermetically sealed. Without being been bound by any particular theory, the inventors hypothesise that moisture from the foodstuff is absorbed by the surface portions of the packaging nearest to the foodstuff. The water is unable to penetrate deep into the packaging due to the moisture-resistant component incorporated into the moulded fibre packaging, but the absorbency of the moulded fibre is such that large amounts of moisture can be absorbed and held at or just below the surface of the packaging, sufficient to cause drying of the packaged foodstuff, which accordingly becomes stale and unappealing.

Accordingly, in a first aspect, the invention provides an article of packaging for a foodstuff, the packaging material comprising moulded fibre, the packaging having an outer surface and an inner surface, the inner surface being proximal to the packaged foodstuff, and wherein the inner surface is coated with a barrier coating which reduces the absorption of liquid water or water vapour by the moulded fibre packaging.

The barrier coating is preferably a thin layer of about 0.01mm to 0.50 mm in thickness, more preferably about 0.05mm to 0.10 mm. Conveniently the barrier coating comprises polyethylene (or polyester) (PE) and/or PMMC. Alternatively the barrier coating may comprise a water-based lacquer such as that used in TECTATM board. All these materials are well-known to those skilled in the art of foodstuff packaging and are readily available commercially. The coating is applied essentially at the surface of the moulded-fibre packaging (or to the surface of any other coating which may also be applied to the moulded-fibre), in contradistinction to moisture-resistant materials which may be incorporated or integrated into the moulded-fibre during manufacture of the latter.

Polyethylene (or polyester) coatings are generally applied by heating the polyethylene to liquefy it, then spraying the molten polyethylene over the inner surface of the packaging.

Typically a relatively thick layer of molten polyethylene is applied, and the excess removed by scraping with a blade to leave a level, thin coating. A conventional density of barrier coating, especially polyethylene coating, would be about l5gms per square metre.

Moulded fibre packaging articles are typically produced with one rough, grainy side and one smooth side. This is a consequence of the moulding method of manufacture. Once a homogeneous mix of pulped fibre has been produced, the slurry or mix is poured into a mould, the lower surface of which typically comprises a fine mesh. The pulp is then compacted and water removed from the mixture by the application of suction, the water being sucked through the holes in the mesh. The mesh leaves a rough imprint on the surface of the moulded pulp which, at this stage, is still soft. The moulded pulp is then dried and hardened by heating in a heater (e.g. oven) for about 90 seconds. Hitherto, largely for aesthetic reasons, the outer surface of the packaging (that is most readily apparent to a consumer prior to purchase) has been the smooth side, and the inner surface has been the rough grainy side. In contrast, in the present invention, the moulded fibre packaging article will preferably have the rough, grainy side on the outer surface, and the smooth side on the inner surface. This is to facilitate the deposition of a thin, relatively even layer of the barrier coating. The undulating, lumpy" nature of the rough side would be impossible to coat completely without applying a relatively thick barrier coating.

The moulded fibre packaging article of the invention may, as conventionally, comprise an integral moisture-resistant material incorporated into the thickness of the packaging.

Alternatively, because of the barrier coating on the inner surface, it may be possible (in at least some embodiments) to omit the integral moisture-resistant material.

Not only has the need for a barrier coating not previously been recognised, it has also been technically difficult to apply such a barrier coating to the inner surface of a moulded fibre packaging article hitherto.

A second disadvantage associated with moulded fibre as a packaging material for foodstuffs is that hitherto it has only been possible to form relatively shallow articles via the moulding process. The present inventors have found that it is now possible to form much deeper containers and, in consequence it is now possible to form types of packaging which could not previously be produced.

Thus in a second aspect the invention provides an article of packaging for a foodstuff, the packaging comprising moulded fibre, and having a maximum depth of at least 70mm.

Preferably the article of packaging has a maximum depth of at least 75mm, more preferably a maximum depth of at least 80mm and most preferably a maximum depth of at least 85mm. (For present purposes the maximum depth of the article means the vertical separation between the lowermost point and the uppermost point when the article is on a horizontal surface and orientated thereon so as to project above the surface by the least amount possible).

In a preferred embodiment the article of packaging of the first or second aspect of the invention comprises a generally triangular prism-shaped container for triangular-cut sandwiches. In preferred embodiments, the article of packaging is in accordance with both the first and second aspects of the invention. The packaging article of the invention may advantageously comprise one or more ribs, typically located in one or more walls of the article. In one embodiment the ribs are located in the two side walls of a triangular prism-shaped container for triangular-cut sandwiches. The ribs may be formed by localised thickening of the moulded-fibre packaging material and/or may be formed by inward projection of the wall into the space in which the foodstuff is received (i.e. with or without thickening of the wall).

The ribs serve two functions. Firstly, they increase the strength and rigidity of the packaging. Secondly, they prevent the packaged foodstuff from coming into contact with the packaging along the whole face of the wall(s) in which the ribs are located. This can help to facilitate removal of the foodstuff (especially a sandwich) from the packaging, and may be desirable in preventing the foodstuff from becoming smeared over the packaging and possibly provide the foodstuff with increased impact protection.

In other embodiments, there are no such ribs, and the inner walls of the packaging are essentially flat. This avoids creating air pockets around the foodstuff which can have a detrimental effect on freshness in some circumstances.

In a typical embodiment, the invention provides an article of packaging for two or three triangular-cut sandwiches, the article of packaging comprising a main body of moulded fibre inside which the sandwiches are received. Once the sandwiches are placed inside the main body of the packaging, a lid is sealed to the main body which, preferably, forms a substantially hermetic seal. Desirably the lid is heat-sealed to the main body by application of heat and pressure, and using a heat-sealable adhesive coating, such as polyester or a water-based lacquer. Alternatively conventional glues or adhesives may be employed.

The lid will preferably substantially consist of biodegradable materials, such that the article of packaging as a whole (i.e. the main body and the lid) will be essentially formed from biodegradable materials. The lid will typically comprise card or the like and be provided with a transparent window portion, to allow prospective customers to view the packaged sandwiches. Preferably such a window portion will be formed from a biodegradable cornstarch film or similar such material.

The lid for the packaging article could be provided as an integral portion of the packaging article (e.g. hingeably attached to the main body prior to insertion of the foodstuff into the main body), or may be provided separately and attached or sealed to the main body once the foodstuff has been inserted.

Preferably, the packaging article and/or lid will be provided with means to facilitate opening of the packaging and/or partial or total separation of the lid from the rest of the packaging. For example, perforations may be provided on the lid, on the moulded fibre packaging, or both. The perforations might, for example, be placed along a corner and/or side of packaging. Alternatively, one or more portions of the lid may be extended well beyond the rest of the packaging, so as to provide a flap or tab which can be grasped to facilitate opening of the packaging. Typically such an extended portion is provided at a corner of the lid.

Advantageously the article of food packaging will be stackable, such that large numbers of the packaging article may be stored in a small volume.

In a third aspect the invention provides a method of making an article of packaging for a foodstuff, the method comprising the steps of forming a moulded fibre packaging article, and coating the inner surface of the article (to be proximal to the foodstuff when packaged) with a barrier coating to reduce the permeability of the packaging.

Preferably the barrier coating comprises a synthetic plastics material or a water-based lacquer. Conveniently the barrier coating is applied by spraying a suitable coating substance onto the inner surface. Suitable coating materials include, in particular, PE and PMMC.

The invention will now be further described by way of illustrative example and with reference to the accompanying drawing, in which: Figure 1 is a perspective view of an article of packaging in accordance with the first and second aspects of the invention.

For the avoidance of doubt it is hereby explicitly stated that any feature described herein as "preferable", "desirable", "convenient", "advantageous" or the like may be used in the invention in isolation, or in any combination with any other feature or features so described, unless the context dictates otherwise.

Detailed Description of an Embodiment

Referring to Figure 1, there is provided a sandwich container (2) in accordance with both the first and second aspects of the invention. The container is shaped and dimensioned to accommodate two triangular cut sandwiches of conventional size and thickness.

The main body of the packaging is formed from moulded fibre, the fibre being processed virgin pulp obtained from renewable and sustainable sources such as sugar cane and reed.

The packaging takes the form of a generally triangular prism substantially defining a space (4) to receive the sandwiches. The packaging has two parallel side walls (6), a back wall (8) and a base wall (10). The back wall (8) and base wall (10) meet at an angle of approximately 900. The entrance to the space (4) is 80mm wide and 170mm long. The width of the space (4) is gradually tapered such that, at the apex of the package the width of the space is only 65mm wide. This serves to pinch the sandwiches at the bottom, holding them securely within the packaging at the base, whilst the wider opening allows a consumer to insert a finger or thumb into the package to extract a sandwich therefrom. In addition the tapering facilitates stacking of the empty packages, one inside another.

The wall of the packaging is very thin (about 1mm thickness). The packaging is thus extremely light but, due to the nature of the moulded fibre material, rigid and quite strong.

The strength of the packaging is increased by the provision of five parallel ribs (12) in each side wall (6) of the package. These are shallow protrusions of the side walls (6) into the space (4) and, in this embodiment, are formed by indenting the wall rather than by thickening thereof. Other embodiments may be provided which are substantially identical but which have different numbers or arrangements of ribs, or may have no ribs at all.

The entrance to the space (4) inside the packaging is surrounded by a narrow out-turned flange (14), about 12mm wide, around the periphery of the packaging. A lid (not shown) may be secured to this flange, preferably by a heat-sealable adhesive.

A barrier coating of a heat-sealable adhesive substance, such as polyethylene or polyester (PE), PMMC, or a water-based lacquer, is applied to the inner side of the packaging. This reduces or substantially eliminates the absorption of water from the packaged foodstuff by the moulded fibre content of the packaging, enabling sandwiches contained within the sealed packaging to remain fresh without drying out, over a period of 2 or 3 days, thus giving the product the extended shelf-life associated with plastics packaging, but in a biodegradable material.

The maximum depth of the packaging article is about 85mm. This is measured when the flange portion (14) is placed lowermost on a horizontal surface -this orientation gives the least possible projection above the horizontal surface.

Example

Identical pairs of sandwiches were obtained from a commercial source, in sealed plastic packs. A variety of different fillings were tested (including roast chicken and salad; egg and bacon). The sandwiches were removed from the plastic packs in which they were purchased. One of the pair of sandwiches was placed in a polyethylene-coated, moulded fibre carton in accordance with both aspects of the present invention, and a cardboard lid applied to seal the carton (test pack). The other of the pair of sandwiches was placed in an identical carton but without a polyethylene coating, and a cardboard lid applied. This was the control pack.

Both test and control packs were then stored at 4 and inspected at regular intervals, for curling of the bread slices (assessed visually) and for drying-out of the bread.

Amount of curling after: 8 hrs 24hrs 72hrs Control Pack +1,iV+I Test Pack ---After as little as 8 hours storage in the control pack, the sandwiches were found to be dry and curling, whilst the sandwiches in the test pack were still perfectly fresh and moist. It was found that, using the moulded-fibre coated carton of the invention, sandwiches remained fresh and appetising following storage for up to 5 days at 4 C, which is equivalent to the shelf-life of sandwiches in sealed plastic packs although, of course, the packs of the invention have the great advantage of being almost entirely biodegradable.

Claims

Claims 1. An article of packaging for a foodstuff, the packaging

material comprising moulded fibre, the packaging having an outer surface and an inner surface, the inner surface being proximal to the packaged foodstuff, and wherein the inner surface is coated with a barrier coating which reduces the absorption of liquid water and/or water vapour by the moulded fibre packaging.
2. An article according to claim 1, wherein the barrier coating comprises polyethylene, polyester, PMMC, or a water-based lacquer.
3. An article according to claim 1 or 2, wherein the barrier coating is applied by spraying.
4. An article according to any cue of claims 1, 2 or 3, wherein the coating is applied at a rate of l5grams per square metre.
5. An article according to any one of the preceding claims, wherein the article is adapted and configured to package triangular-cut sandwiches.
6. An article of packaging for a foodstuff, the packaging comprising moulded fibre, and having a maximum depth of at least 70mm.
7. An article according to claim 6, having a maximum depth of at least 75mm.
8. An article according to claim 6, having a maximum depth of at least 80 mm.
9. An article according to claim 6, having a maximum depth of at least 85 mm.
10. An article according to any one of claims 6-9 and further in accordance with any one of claims 1-5.
11. An article according to any one of the preceding claims further comprising a lid.
12. An article according to claim 11, wherein the lid comprises card.
13. An article according to claim 11 or 12, wherein the lid is heat-sealed to the rest of the packaging.
14. An article according to any one of claims 11-13, wherein the lid comprises a transparent window portion.
15. An article according to any one of the preceding claims, wherein the article is substantially formed from biodegradable materials.
16. An article according to any one of the preceding claims, substantially as hereinbefore described and with reference to the accompanying drawing.
17. A method of making an article of packaging for a foodstuff, the method comprising the steps of: forming a moulded fibre packaging article; and coating the inner surface of the article (proximal to the foodstuff when packaged) with a barrier coating to reduce the absorption of liquid water or water vapour from the foodstuff by the packaging.
18. A method of packaging a foodstuff, especially a sandwich, the method comprising the steps: of inserting the foodstuff into an article of packaging in accordance with any one of claims 1-16; and sealing a lid to the article to enclose the packaged foodstuff.
19. A method according to claim 18, wherein the step of sealing the lid comprises heat-sealing.