WO2009013489A1

WO2009013489A1 - Method and apparatus for manufacturing a food packaging container

Info

Publication number: WO2009013489A1
Application number: PCT/GB2008/002518
Authority: WO
Inventors: Peter Davies
Original assignee: Zeus Group Limited
Priority date: 2007-07-25
Filing date: 2008-07-24
Publication date: 2009-01-29
Also published as: GB0714470D0; GB2449507A

Abstract

This invention relates to a method of manufacturing a food packaging container, an apparatus for manufacturing a food packaging container and a food packaging container produced according to the method. This invention relates to a method and apparatus for manufacturing food packaging containers from sugar cane bagasse. The resulting container including a polymer liner that is bonded to the internal face of the tray. The addition of the polymer liner ensuring that the container is capable of accepting a variety of ambient, chilled, fresh and frozen foodstuffs and the product is entirely biodegradable and compostable. After use, the bagasse tray is 100% compostable, and the polymer liner can be removed by a fibre tear and disposed of separately if desired. In order to further facilitate the separation of the polymer liner from the bagasse tray, the tray can be provided with a breakable tear tab.

Description

METHOD AND APPARATUS FOR MANUFACTURING A FOOD PACKAGING CONTAINER

This invention relates to a method of manufacturing a food packaging container, an apparatus for manufacturing a food packaging container and a food packaging container produced according to the method. In particular, this invention relates to a method and apparatus for manufacturing food packaging containers from sugar cane bagasse. The resulting container having a polymer liner that is bonded to the internal face of the tray. The addition of the polymer liner ensuring that the container is capable of accepting a variety of ambient, chilled, fresh and frozen foodstuffs and, after use, the polymer liner can be easily removed. The food packaging container is entirely biodegradable and compostable .

Insofar as much of the western world is concerned, the ready meals market has grown considerably in recent years. Consumer demand for convenience foods, a rise in freezer and microwave oven ownership, and an increase in one and two-person households are all factors driving this market. Hitherto, the most popular material for ready meal containers has been PET (polyethylene terephthalate) and PEN (polyethylene naphthalate) which are polymers having advantages in terms of costs, good thermostability and lightweight. In use, this type of container does have a number of shortcomings and after re-heating the foodstuff, it is often found that the rigidity of the container decreases which can be dangerous and also makes it difficult to remove the foodstuff form the container. From an environmental point of view, whilst these plastic PET or PEN products can be recycled where appropriate facilities exist, the industry is still struggling to keep pace with growth of the virgin product, and millions of plastic containers are still buried in landfill sites every year. Another well-known environmental problem is that these plastics are manufactured from non-renewable resources such as oil, coal and natural gas.

In an attempt to address these problems, the applicant of the present application filed UK Patent Application No. 0618489.9 on 20 September 2007 which discloses a food packing container suitable for containing a wide variety of chilled and frozen foodstuffs. The container described therein is however not able to contain all fresh, ambient and chilled produce as the acidity of some of these foodstuffs can cause the contents to leak through the sugar cane tray, which is obviously unacceptable.

It is therefore an object of the present invention to provide a method and apparatus for manufacturing food packaging containers that include a polymer liner bonded to the internal face of the tray. The food packaging container according to the present invention therefore allows the containment of a wide variety of fresh, ambient, chilled and frozen foodstuffs that is capable of withstanding a wide temperature range from deeply frozen to regeneration of the food in microwave, conventional or fan assisted ovens. The food packaging container according to the present invention can be manufactured quite readily using a raw material, namely sugar cane pulp or "bagasse" , which is the biomass remaining after sugar cane stalks are crushed to extract their juice, and which is a sustainable crop. After use, the bagasse tray is 100% compostable, and the polymer liner can be removed by a fibre tear and disposed of separately if desired. In order to further facilitate the separation of the polymer liner from the bagasse tray, the tray can be provided with a breakable tear tab. In use, the thermal properties of the food packaging container according to the present invention are such that a user can safely remove the container from an oven without insulated gloves .

According to the present invention there is provided a method of manufacturing a food packaging container, comprising the steps of: introducing a water-based sugar cane pulp solution to a moulding chamber; extracting said water from said sugar cane pulp solution and forming an approximate profile of the food packaging container; transferring the sugar cane pulp profile obtained to a tooling head and applying pressure and heat; and applying a polymer liner to an internal face of the food packaging container.

Also according to the present invention there is provided an apparatus for manufacturing a food packaging container, comprising: at least one moulding chamber containing a suitable quantity of water-based sugar cane pulp solution; extracting means for extracting said water from said sugar cane pulp solution and forming an approximate profile of the food packaging container; means for transferring the sugar cane pulp profile obtained to a tooling head and applying pressure and heat ; and means for applying a polymer liner to an internal face of the food packaging container.

Further according to the present invention there is provided a food packaging container formed from sugar cane pulp, the food packaging container comprising: at least one compartment defining a base, side sections and peripheral outer rim, said at least one compartment being suitable for containing foodstuffs; a plurality of indents situated on said base and/or said side sections to provide mechanical rigidity; and a peelable liner portion formed in an internal face of the food packaging container.

Preferably, the step of extracting said water from said sugar cane pulp solution and forming an approximate profile of the food packaging container is performed using a meshed tooling head.

Further preferably, the step of extracting said water from said sugar cane pulp solution through a meshed tooling head is performed using under vacuum. The water-based sugar cane pulp solution may also include additives to provide oil, chemical and water resistance in the finished product. In use, the tooling head may be substantially solid and includes raised features for embossing the manufacturers' logos and/or food grade standards and/or a plurality of indents.

Preferably, the plurality of indents on said tooling head allow for increased mechanical rigidity and/or mechanical de-nesting of a plurality of said food packaging containers .

Further preferably, the step of applying a polymer liner to an internal face of the food packaging container is performed using thermoforming, blow moulding or spray application. Said polymer liner being formed from PET (polyethylene terephthalate) .

In use, the present invention further comprises the steps of transferring at least one food product to said food packing container and aligning said food packing container and a lid and applying pressure and heat to form a peelable seal .

Preferably, after use, said polymer liner can be removed by a fibre tear.

Further preferably, to facilitate the separation of the polymer liner from the food packaging container, the food packaging container can be provided with a breakable tear tab.

It is believed that a method and apparatus for manufacturing a food packaging container in accordance with the present invention at least addresses the problems outlined above. In particular, the advantages of the present invention are that the containment of a wide variety of fresh, ambient, chilled and frozen foodstuffs is possible over a wide temperature range from deeply frozen to the regeneration of the food in microwave, conventional or fan assisted ovens. Advantageously, the food packaging container according to the present invention can be manufactured quite readily using a raw material, namely sugar cane pulp or "bagasse", which is a sustainable crop. After use, the bagasse tray is 100% compostable, and the polymer liner can be removed by a fibre tear and disposed of separately if desired. In order to further facilitate the separation of the polymer liner from the bagasse tray, the tray can be provided with a breakable tear tab. Further advantageously, In use, the thermal properties of the food packaging container according to the present invention are such that a user can safely remove the container from an oven without insulated gloves.

It will be obvious to those skilled in the art that variations of the present invention are possible and it is intended that the present invention may be used other than as specifically described herein.

A specific non-limiting embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Fig. 1 is a flow diagram showing the various steps involved in the manufacture of a food packaging container in accordance with the present invention;

Fig. 2 shows a perspective view from above of one type of food packaging container that can be produced according to the present invention;

Fig. 3 shows a plan view from above of a further type of food packaging container that can be produced according to the present invention and which also includes a breakable tear tab to ensure the separation of the polymer liner from the container; and

Fig. 4 shows a further perspective view of the food packaging container including a breakable tear tab as depicted in Figure 3.

Referring now to the drawings, the manufacture of food packaging containers in accordance with the present invention is disclosed in detail in Fig. 1. The raw material used to manufacture such a food packaging tray is pure sugar cane pulp or "bagasse" reclaimed after extraction of the sugar. The manufacture of the container follows a number of processing steps, as detailed below.

In essence, as shown in Fig. 1, the raw material (pure sugar cane reclaimed after the extraction of the sugar) is processed to form a pulp. The pulp is then introduced to moulds, which press the raw material to the required shape. In use, after filling the food packaging container with the various food product or products (not shown) , the food container and lid are aligned in packaging equipment and are formed together using suitable heat and pressure.

To the best of our knowledge, this is the only- product which has the ability to retain its integrity at -40⁰C and in an oven at 220⁰C. After use, the food packaging container is biodegradable and, in fact, is compostable .

Further detail of the manufacturing process will now be described. In particular, sugar cane cultivated from plantations is transported to the manufacturing facility for quality assurance tests and storage (steps 1 to 3) . The sugar cane is then soaked for a predetermined period of time (step 4) prior to draining (step 5) . The sugar cane is then pulverised into microparticles through a series of agitation and mixing cycles (steps 6 to 11) . The pulverised cane is then added to a water-based solution containing additives for oil, chemical, and water resistance in finished product (steps 12 to 15) . Following this the raw pulp solution is stored in large silos which provide constant mixing (step 16) .

To form the moulded trays (step 17) , a two-stage moulding process is utilised. The first stage of the tray shaping process (step 18) involves the pressurised extraction of the raw pulp solution from the silo. The pulp is then added to a precise volume of water in a moulding chamber which completely covers the metal mould profiles for whichever design is being manufactured. Using vacuum extraction, the water is then expelled from the mould chamber leaving a uniform layer of pulp as the design profile. This is possible by using a first tooling head formed as a wire mesh which allows the water in the solution to be extracted.

This pulp profile is then transferred to a second tooling head where controlled pressure and heat are applied to provide the finished product.

The edges of the product are then pressed out (step 19) , prior to the application of the polymer liner to the internal face of the tray (step 20) . The application of the polymer liner to the internal face of the tray can be achieved by thermoforming, blow moulding or spray application and which results in a uniform distribution of polymer being bonded to the container. No separate adhesives are required.

In a preferred embodiment, the application of the polymer liner to the internal face of the tray is achieved using the process of thermoforming. The, usually, PET (polyethylene terephthalate) polymer liner is firstly extruded to various thicknesses depending on the type of tray to be manufactured. For food tray applications, this is optimised at a thickness of around 32microns. The polymer liner is then drawn over the surface of the sugar cane product in a thermoforming machine and heat is then applied to the liner to raise its temperature above the melt point of the liner, which can be as high as 600⁰C. When this temperature is achieved, the liner is then blown to form a dome and then a vacuum is formed at approximately 2mB drawing the liner towards the internal surface of the sugar cane tray. Whilst still hot, the liner is finally secured using a plug assist method by pushing the film on to the internal face of the tray using a 'plug' made from resin, HDPE or wood, which is shaped to the internal surface of the sugar cane tray.

The bond created by the fusion of the polymer liner to the fibres of the sugar cane product effectively bond the polymer liner to the tray for use. The structure of the polymer film is stronger than the fibre structure of the sugar cane tray and, after use, the liner can be separated from the sugar cane tray by pulling at the film that tears away from the sugar cane product in one piece without sticking or shredding, and which is referred to herein as a "fibre tear" . In use, the inclusion of the polymer liner in the container offers a high resistance barrier to pH, bacterial migration, moisture migration and oil migration.

Following the application of the polymer liner, the product is passed through a metal detector (step 21) to ensure that any ferrous and stainless steel contaminates are discarded. The product is then UV disinfected (step 22) prior to packing and storage (step 23 to 25), before being shipped for food fill operation.

Individual design features (such as embossing of manufacturers' logos; food grade standards and a plurality of indents) are present on the second tooling head to allow for and mechanical de-nesting of finished products required by the food processing industry.

To the best of our knowledge, this is the only product which has the ability to retain its integrity at -40⁰C and in an oven at 220⁰C. After use, the food packaging container tray is 100% compostable, and the polymer liner can be removed by a fibre tear and disposed of separately if desired. The product, in use, is stable during regeneration of food in a microwave, conventional or fan assisted ovens. In use, the thermal properties of the food packaging container are such that a user can safely remove the container from an oven without insulated gloves.

Fig. 2 shows one type of food packaging container that can be produced according to the present invention. The food packaging container shown in Fig. 2 consists of a tray 10 having an outer rim 12 which defines at least one compartment 14 which, in use, accommodates the food product (not shown) , and which can be subsequently frozen, chilled or held at ambient temperature. Design features in each tray 10 enable the present invention to be easily and successfully integrated onto all production lines used by various food manufacturers.

Each tray 10 has a series of indents 16 situated around the base, which enhances both vertical and horizontal strengths. The indents 16 allow for and mechanical de-nesting of finished products required by the food processing industry. Triangular indents (not shown) located on the top surface of the tray can also be used to increases the stability of the present invention to remain rigid throughout the packaging cycle, and in use .

The outer rim 12 dimensions of each tray are designed to facilitate a peelable seal with a lid (not shown) which can be formed from a polymer liner or made from sheets of rolled sugar cane bagasse. The bonding process of the lid to the rim 12 of the tray 10 is achieved by heat pressure only; no adhesives are used. The polymer liner (not shown) that is bonded to the internal face of the tray 10 cannot be seen in Fig. 2 but the skilled person will appreciate that such is a thin transparent liner. After use, the liner can be removed by a fibre tear and disposed of separately, if desired. The bagasse tray 10 is 100% compostable.

Figs . 3 and 4 show a further type of food packaging container that can be produced in accordance with the present invention. The food packaging container shown in Figs. 3 and 4 again consists of a tray 10 having an outer rim 12 which defines at least one compartment 14 which, in use, accommodates the food product (not shown) , and which can be subsequently frozen, chilled or held at ambient temperature. Again, the tray 10 includes a series of indents 16 which allow for mechanical de-nesting of the finished product. The tray 10 shown in Figs. 3 and 4 also includes a tear tab 18 which is formed along a line of weakness or perforations 20 in the rim 12. This improves the separation of the thin transparent liner from the tray 10. As described above, after use, when the product (not shown) has been removed from the tray 10, the liner can be separated from the sugar cane tray 10 by pulling at the film that tears away from the sugar cane product 10 in one piece without sticking or shredding, and which has been referred to herein as a "fibre tear" . In order to facilitate the separation of the polymer liner from the bagasse tray 10 a user can simply grip the tear tab 18 with a forefinger and thumb, an the upward movement is enough to cause the liner to separate from the tray 10.

The tear tab 18 is formed after the tray 10 has been through the second tooling head and before the liner is thermoformed into the tray 10. The perforations 20 are produced using a cutting tool that provides a series of uniform perforations of a specific shape, and which are determined by the actual design of the tray 10. The various design shapes are concave and situated on the rim 12. It is the movement of the tab 18 which breaks the surfaces between the perforations 20 and allow the tab 18, with the liner attached, as a whole, to initiate separation in one piece.

Various alterations and modifications may be made to the present invention without departing from the scope of the invention.

Claims

1. A method of manufacturing a food packaging container, comprising the steps of: introducing a water-based sugar cane pulp solution to a moulding chamber; extracting said water from said sugar cane pulp solution and forming an approximate profile of the food packaging container; transferring the sugar cane pulp profile obtained to a tooling head and applying pressure and heat; and applying a polymer liner to an internal face of the food packaging container.

2. The method of claim I₇ wherein the step of extracting said water from said sugar cane pulp solution and forming an approximate profile of the food packaging container is performed using a meshed tooling head.

3. The method of claim 2, wherein the step of extracting said water from said sugar cane pulp solution through a meshed tooling head is performed using under vacuum.

4. The method of claim 1, wherein said water-based sugar cane pulp solution further comprises additives to provide oil, chemical and water resistance in the finished product .

5. The method of claim 1, wherein said tooling head is substantially solid and includes raised features for embossing the manufacturers' logos and/or food grade standards and/or a plurality of indents.

6. The method of claim 5, wherein the plurality of indents on said tooling head allow for increased mechanical rigidity and/or mechanical de-nesting of a plurality of said food packaging containers.

7. The method of claim 1, further comprising the step of marking a series of perforations or line of weakness into a section of said tray to form a tear off portion.

8. The method of claim 1, wherein the step of applying a polymer liner to an internal face of the food packaging container is performed using thermoforming, blow moulding or spray application.

9. The method of claim 1, wherein the step of applying a polymer liner to an internal face of the food packaging container further comprising the steps of: heating said polymer liner above its melt point; forming a vacuum in the region of said internal face of the food packaging container; and pushing said polymer liner on to said internal face of the food packaging container.

10. The method of claim 1, further comprising the steps of transferring at least one food product to said food packing container and aligning said food packing container and a lid and applying pressure and heat to form a peelable seal .

11. The method of claim 1, wherein said polymer liner can be removed by a fibre tear.

12. An apparatus for manufacturing a food packaging container, comprising: at least one moulding chamber containing a suitable quantity of water-based sugar cane pulp solution; extracting means for extracting said water from said sugar cane pulp solution and forming an approximate profile of the food packaging container; means for transferring the sugar cane pulp profile obtained to a tooling head and applying pressure and heat ; and means for applying a polymer liner to an internal face of the food packaging container.

13. The apparatus of claim 12, wherein said extracting means for extracting said water from said sugar cane pulp solution and forming an approximate profile of the food packaging container is performed using a meshed tooling head.

14. The apparatus of claim 13, wherein said extracting means for extracting said water from said sugar cane pulp solution through a meshed tooling head is performed using under vacuum.

15. The apparatus of claim 12, wherein said water-based sugar cane pulp solution further comprises additives to provide oil, chemical and water resistance in the finished product.

16. The apparatus of claim 12, wherein said tooling head is substantially solid and includes raised features for embossing the manufacturers' logos and/or food grade standards and/or a plurality of indents.

17. The apparatus of claim 16, wherein the plurality of indents on said tooling head allow for increased mechanical rigidity and/or mechanical de-nesting of a plurality of said food packaging containers .

18. The apparatus of claim 12, further comprising means for marking a series of perforations or line of weakness into a section of said tray to form a tear off portion.

19. The apparatus of claim 12, wherein said means for applying a polymer liner to an internal face of the food packaging container further comprises thermoforming, blow moulding or spray application.

20. The apparatus of claim 12, wherein said means for applying a polymer liner to an internal face of the food packaging container further comprises: means for heating said polymer liner above its melt point ; means for forming a vacuum in the region of said internal face of the food packaging container; and means for pushing said polymer liner on to said internal face of the food packaging container.

21. The apparatus of claim 12, further comprising means for transferring at least one food product to said food packing container and aligning said food packing container and a lid and applying pressure and heat to form a peelable seal.

22. The apparatus of claim 12, wherein said polymer liner can be removed by a fibre tear.

23. A food packaging container formed from sugar cane pulp, the food packaging container comprising: at least one compartment defining a base, side sections and peripheral outer rim, said at least one compartment being suitable for containing foodstuffs; a plurality of indents situated on said base and/or said side sections to provide mechanical rigidity; and a peelable liner portion formed in an internal face of the food packaging container.

24. The food packaging container of claim 23, wherein said sugar cane pulp includes additives to provide oil, chemical and water resistance.

25. The food packaging container of claim 23, wherein said plurality of indents aid mechanical de-nesting of a plurality of said food packaging containers.

26. The food packaging container of claim 23, wherein said peelable liner portion permits the containment of a wide variety of fresh, ambient, chilled and frozen foodstuffs .

27. The food packaging container of claim 23, wherein said peelable liner portion can be removed by a fibre tear.

28. The food packaging container of claim 23, further comprising a tear tab 18 which is formed along a line of weakness or perforations 20 on the outer rim 12.

29. The food packaging container of claim 23, wherein said peelable liner portion offers a high resistance barrier to pH, bacterial migration, moisture migration and oil migration.

30. A method of manufacturing a food packaging container as hereinbefore described.

31. An apparatus for manufacturing a food packaging container as described herein with reference to Figs. 1 and 2 of the accompanying drawings .

32. A food packaging container as described herein with reference to Figs. 1 and 2 of the accompanying drawings.