WO2008104181A1

WO2008104181A1 - A self-venting container, tray and lid for heating of food

Info

Publication number: WO2008104181A1
Application number: PCT/DK2008/050041
Authority: WO
Inventors: Flemming Troldtoft; Benny Birger Rasmussen
Original assignee: R. Faerch Plast A/S
Priority date: 2007-02-27
Filing date: 2008-02-19
Publication date: 2008-09-04
Also published as: ATE506283T1; EP2114794A1; EP2114794B1; DE602008006360D1

Abstract

The present invention relates to a self-venting container for heatingfood, where steam may escape during the heating without having a valve installed in the lid (1).The container comprises a tray (2) and a lid (1) which are connected by a rim (3) and anoverhang (4). At least one of the rim and the overhang comprise at least one indentation (5), said indentation being arranged in a position within where the rim and overhang overlap. The rim and the overhang provide a connection which will resist an internal pressure up to a predetermined value, above which pressure is released locally at the indentation. Alternatively, the indentation extendsfroman inward position in the container to an outward position such that a passage out is provided, and where the indentation is adapted to have a sufficiently small cross-section in order to on one side allow release of air, gas' and/or steam via the passage, when food is heated in the container, and on another side prevent liquid from escaping via the passage.

Description

A SELF-VENTING CONTAINER, TRAY AND LID FOR HEATING FOOD

FIELD OF THE INVENTION

The present invention relates to a self-venting container adapted for holding food, including while at least the food is heated. The container comprises a tray having at least one food holding compartment and at least one lid adapted to close the food holding compartment such that food placed in the food holding compartment is enclosed when said lid is connected to the tray. The invention further relates to a tray and to a lid for a similar purpose, as well as to a use of such a container, tray or lid.

BACKGROUND OF THE INVENTION

Food is stored in containers for many purposes. The container protects the food during storage and handling, as well as ensures that no food is spilled. It is also convenient, in case the food is to be heated e.g. before consumption, to do so while the food remains in the container. To keep protecting the food the lid is preferably not removed until later. The lid also enables the food to stay properly in the container during heating. In an oven the food is less easily dried out when the lid is attached to the container.

Leaving the lid on, however, creates a problem because air and/or gas in the container is also heated and thereby exerts an increased pressure in the container. Moreover, when heating in an oven or microwave oven, any presence of water or liquid will cause steam to build up in the container, which will exert an even higher pressure in the container. Such an increased pressure may deform the container, or cause the lid to pop off, or even cause a rupture in the container.

To solve this problem a number of solutions have already been suggested, where either a part of the lid must manually be removed, which is inconvenient, or where a valve is installed in the lid, which is costly and may restrict recycling of the lid. One example is known from EP1127810 which discloses a container for packaging food, in which a sheet seals a vent hole formed at a portion of the container and which cannot so easily be peeled off but, when the food is heated by a microwave oven, the sheet automatically comes off at the time when the food contained in the container has reached the adequately cooked state, because the peeling strength is reduced at an elevated temperature.

SUMMARY

It is an object of the present invention to provide solutions to the aforementioned problems without added cost or inconvenience. Other objects appear from the description and the appended figures. One aspect of the invention is defined by the features of a container according to claim 1. According to the invention the objects are obtained in a way where each of the lid and tray may be formed in a usual process for making such items without a venting function, and all that is needed is a modification of the dies, moulds or matrices used. This is due to the fact that the container is modified to release steam from the container via the interface between the lid and the tray.

More specifically, the tray and the lid are mutually connectable by comprising a rim extending around a periphery of the food holding compartment and an overhang adapted to overlap and engage the rim. The rim may be provided on the tray and the overhang be provided on the lid, or vice versa. At least one of the rim and the overhang comprise at least one indentation, which is arranged in a position within where the rim and overhang overlap, when connected. Depending on the size and extent of the indentation it may be used in at least two alternative ways.

One way involves that the rim and the overhang, when connected, provide a connection which will resist a pressure which is higher in the food holding compartment than outside the food holding compartment when said pressure is up to a predetermined value. The indentation, rim and overhang are arranged such that a pressure which is higher in the food holding compartment than outside the food holding compartment is released locally at the indentation by deflection of a part of the overhang and/or a part of the rim, which will open a passage out from the food holding compartment via the indentation while overall maintaining the connection between the rim and the overhang, when food is heated in the container and said pressure exceeds a predetermined value. This means that the container is closed as long as the food is not heated. When subjected to heating, an internal pressure is gradually built up which exerts a force on the lid. At a predetermined pressure the force on the lid causes a slight deflection of a part of the overhang and/or rim, which may expose the indentation which may then provide a passage out of the container. Or the indentation may extend to an outside position such that, as soon the indentation is exposed from the inside due to the force exerted on the lid, the passage is created. Or the indentation may extend into the food holding compartment such that access to the indentation is already provided. In this case must the air, gas and/or steam via the indentation convey the internal pressure to the rim and the overlap, which at a predetermined pressure deflects to locally release the pressure.

The other way involves the fact that the indentation extends from an inward position in the food holding compartment where the rim and overhang do not engage, when connected, via a position within where the rim and overhang overlap, when connected, and to an outward position away from the food holding compartment where the rim and overhang do not engage, when connected, such that a passage out from the food holding compartment via the indentation is provided, and where the indentation is adapted to have a sufficiently small cross-section in order to, on one side allow release of air, gas and/or steam via the passage, when food is heated in the container, and on another side prevent liquid from escaping via the passage. In this case the container is not completely tight, however, tight enough to prevent liquid from escaping, which is obtained by the design of the indentation, whereby also air, gas and/or steam may be released through the indentation. In this case, however, the rim and the overlap may still locally deflect at the indentation to increase the flow out of the container and more efficiently release internal pressure. Also, in this case, it is possible to allow a pressure, which is higher outside the container than inside the container, to enter the container via the indentation in order to prevent unwanted deformation of the container.

In one preferred embodiment the indentation has a smaller cross-sectional area at an inward position and a larger cross-sectional area at a position within where the rim and overhang overlap, when connected. This increases the ability of the indentation to prevent liquid from escaping via the indentation and at the same time helps releasing air, gas and steam which may pass the smaller cross-sectional area and then easier pass where the cross-sectional area is larger.

Another preferred embodiment involves that the indentation is oblong and placed with a longitudinal axis perpendicular or slanted relative to the rim or the overhang. The indentations may have any suitable shape such as being generally circular, oval, triangular, rectangular, polygonal as well as any oblong shape, which may be, straight or curved.

A further preferred embodiment involves that the rim or the overhang comprises a plurality of indentations, preferably arranged equidistantly. By using a plurality of indentations each individual indentation may be made smaller and hence easier prevent liquid from escaping. It also has the effect that steam is released in a more evenly distributed and calm manner.

Another preferred embodiment involves that a plurality of indentations are provided in the rim and/or the overhang by, in a direction along the circumference of said rim and/or overhang, from time to time decreasing and increasing the width of the rim and/or the overhang in a way where the rim and the overhang in a number of areas are engaged and in a number of areas have a mutual distance. This may include that the rim or the overhang, in a direction along their circumference, has a polygonal shape on at least one side, said side preferably facing the food holding compartment. In a yet further preferred embodiment the overhang may be arranged to snap-on engage the rim at both an inward side facing the food holding compartment as well as an outward side. The snap-on engagement facilitates easy connection of the lid to the tray. By engaging both at an inward and an outward side the connection will be tighter and thereby better withhold a given internal pressure in the container.

Another preferred embodiment involves that the rim may be arranged on the tray and a sealing film is attached to the rim, and overlaps and closes any indentation present in the rim, said sealing film being arranged such that food in the food holding compartment is enclosed and sealed also when the lid is removed. Preferably is the sealing film adapted to at least partly release from the rim when subjected to heating. Such a container may be used for products sold by retailers. When the sealing film releases when subjected to heating, it may not be necessary to remove the film prior to the heating. Otherwise it may be necessary to remove the lid to access the sealing film for removal and then re-attach the lid again.

In a yet further preferred embodiment may the connection between the rim and the overhang as well as the size and number of indentations be adapted to resist pressure exerted by food enclosed in a food holding compartment, said pressure being exerted due to movements during handling and/or transport. This may also include that the connection between the rim and the overhang as well as the size and number of indentations are adapted according to the viscosity of the food enclosed in a food holding compartment. Furthermore, the connection between the rim and the overhang as well as the size and number of indentations are adapted according to the amount of steam released by the food enclosed in a food holding compartment during heating. The exact adaptation must be determined case by case depending on the size of the container, the type of food and composition, etc.

A further preferred embodiment includes that the at least one food holding compartment is arranged such that the tray includes at least one section which may be gripped without touching the food holding compartment while removing the lid after heating. This facilitates handling of the container without burning one's fingers, when the food is heated.

The lid may be hinged to the tray such that the lid is always present together with the tray and may thereby not be lost. Preferably, the lid is made from a polymeric material, preferably at least partly crystallised polyethylene terephthalate (PET), polypropylene (PP), or a laminate comprising polypropylene (PP) and ethylene vinyl alcohol polymer (EVOH).

Also preferably, the tray is made from a polymeric material, preferably at least partly crystallised polyethylene terephthalate (PET), polypropylene (PP), or a laminate comprising polypropylene (PP) and ethylene vinyl alcohol polymer (EVOH).

Especially crystallised polyethylene terephthalate (PET) is well suited for use in heating food because it endures temperatures up to about 200 degrees Celcius or more.

Also preferably, the lid and the tray may be manufactured with a very low thickness both to save material, but also to facilitate heat transfer. This may involve that the lid and/or the tray is manufactured by thermoforming of foil, including a laminate foil having at least two layers. The layers may be made from different materials. The tray and/or the lid may be manufactured in a process comprising rotary moulding melt to mould process, die casting, injection moulding or thermoforming.

A preferred use of a container, tray or lid according to the invention is for heating food in means of transport such as an air plane, a ship, a bus or a train. Because such means of transportation often involve unexpected movements which may e.g. cause a person to loose his/her balance it is of great importance that the lid is left on the container during handling when the food may be cold, but especially after the heating. The container may also be subject to harsh movement while being in an oven when heated on such a means of transportation. This is conveniently obtained by the invention without having to resort to adding special valves in the lid at an increased cost.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a perspective view of a container according to the invention, where only a section of the lid is shown, Fig. 2 shows a perspective view of an embodiment of a tray according to the invention, Fig. 3 shows a perspective view of an embodiment of a lid according to the invention, Fig. 4 -5 show perspective views of other embodiments of a tray and a lid, which may be connected to form a container, Figs. 6-13 are sectional views of a cross-section perpendicular to the rim of containers according to the invention, Fig. 14 is a topview of a lid having a polygonal side in order to provide indentations.

DETAILED DESCRIPTION OF THE INVENTION

The figures show exemplary embodiments of trays and lids, i.e. elements of a container, according to the invention. The figures are merely included as information given as examples to a skilled person of how the invention may be carried out.

Fig. 1 displays a container comprising a tray 2 and a lid 1. Figs. 2 and 3 individually display the tray 2 and the lid 1, respectively. The shape of the tray 2 and the lid 1 may of course be any suitable shape according to purpose, e.g. circular, oval, rectangular, etc. The tray 2 has a rim 3 and a food holding compartment 6. A number of indentations 5 are provided in the rim 3 of the tray 2. The container is adapted for holding food, including while the food is heated in an oven or a microwave oven. The tray 2 and the lid 1 are mutually connectable by the rim 3, which is extending around a periphery of the food holding compartment 6, and an overhang 4. The overhang 4 is adapted to overlap and engage the rim 3. The rim 3 is here provided on the tray 2 and the overhang 4 is provided on the lid 1, but that could be switched round, i.e. such that the rim is provided on the lid and the overhang on the tray. The indentation 5 is arranged in a position within where the rim 3 and overhang 4 overlap, when connected. The indentation 5 may be arranged only where the rim 3 and the overhang 4 overlap, or extend from the food holding compartment to within the overlap, or from the overlap and to the outside, or from the food holding compartment to the outside.

The ear 11 displayed in Fig. 3 enables easy removal of the lid 1 from the tray 2.

Figs. 4 and 5 display a tray 2 and a lid 1, which are connectable. The tray 2 has a rim 3 and a food holding compartment 6. A number of indentations 5 are provided in the overhang 4 of the lid 1. The tray 2 and the lid 1 are mutually connectable by the rim 3, which is extending around a periphery of the food holding compartment 6, and the overhang 4. The overhang 4 is adapted to overlap and engage the rim 3.

Figs. 6-13 display cross-sections of a container comprising a tray 2 having a rim 3 and a lid 1 having an overhang 4. The rim 3 and the overhang 4 overlaps. The cross-sections are taken through an indentation 5. At other positions with no indentation may the rim 3 and the overhang 4 be in contact over the entire overlap. The principles shown would of course also apply in an embodiment, where the rim 3 was on the lid 1 and the overhang 4 was on the tray 2. The indentations 5 shown in Figs. 6-13 may be present either in the rim 3 or the overhang 4. The figures apply in both cases. However, for the sake of clarity is the following description of Figs. 6-13 written as if all the indentations 5 are placed in the rim 3.

In Fig. 6 it is displayed that the rim 3 and the overhang 4 has a snap-on connection at the inside 9 and outside 10. The indentation 5 is provided in the topside of the rim 3. The connection between the lid 1 and the tray 2 is closed until a passage is opened via the indentation 5, when an internal pressure exerts a deflection of the lid 1 at the side 10 and afterwards of the side 9, when the internal pressure is sufficiently high.

In Figs. 7 and 9 it is displayed that the rim 3 and the overhang 4 at the indentation 5 connects at the outside 9. Where no indentations are present may the may the rim 3 and the overhang 4 be in contact over their entire overlap. At the contact surface 7 is access from the food holding container 6 to the indentation 5 closed and at the contact surface 8 is access to the outside closed. The indentation 5 is provided in the topside of the rim 3 and by the inside 10 of the overhang. The connection between the lid 1 and the tray 2 is closed until a passage is opened via the indentation 5, when an internal pressure exerts a deflection of the lid 1 at the side 10 and afterwards of the side 9, when the pressure is sufficiently high. In Fig. 8 is the indentation 5 only closed off at the contact surfaces 7 and 8.

In Figs. 10-12 show embodiments with free access from the food holding compartment 6 into the indentation 5. Only at the contact surface 8 is the indentation closed off relative to the outside. Compared to the embodiments of Figs. 6-9 requires the embodiments of Figs. 10-12 a relatively lower internal pressure before the rim 3 and the overhang 4 will deflect at release the pressure. This of course under the provision that all other design features such as wall thickness, material, dimensions, etc. are kept identical. As seen ffrom Figs. 6- 12 will the rim 3 and the overhang 4, when connected, provide a connection which will resist a pressure, which is higher in the food holding compartment 6, than outside the food holding compartment 6, when said pressure is up to a predetermined value. The indentation 5, rim 3 and overhang 4 are arranged such an increased pressure, which is higher in the food holding compartment 6 than outside the food holding compartment 6, is released locally at the indentation by a deflection of a part of the overhang 4 and/or a part of the rim 3 which will open a passage out from the food holding compartment 6 via the indentation 5 while overall maintaining the connection between the rim 3 and the overhang 4, when said pressure exceeds a predetermined value.

Fig. 13 shows another embodiment, where at the indentation 5, there is no contact at the surfaces 7 and 8. Hence, there is free passage from inside the food holding compartment and the outside, and vice versa. In this case is the indentation 5 adapted to have a sufficiently small cross-section in order to on one side allow release of air, gas and/or steam via the passage and on another side prevent liquid from escaping via the passage. The dimensions are exaggerated for explanatory purposes in Figs. 6-13, especially the gap between the rim 3 and the overhang 4 in Fig. 13.

Fig. 14 shows an embodiment having a plurality of indentations 5 provided in the overhang 4 by, in a direction along the circumference of said overhang 4, the width of the overhang 4 is alternatingly decreasing and increasing. This means that the rim 3 and the overhang 4 in a number of areas are engaged and in a number of areas have a mutual distance. In the present embodiment is the overhang 4, in a direction along its circumference, having a polygonal shape to the side facing the food holding compartment 6. This creates a number of indentations at positions where a distance is present between the rim 3 and the overhang 4.

It is to be understood that the invention as disclosed in the description and in the figures may be modified and changed and still be within the scope of the invention as claimed hereinafter.

Claims

1. A self-venting container adapted for holding food, including while the food is heated, the container comprising a tray having at least one food holding compartment and at least one lid adapted to close the food holding compartment such that food placed in the food holding compartment is enclosed when said lid is connected to the tray, where the tray and the lid are mutually connectable by comprising a rim extending around a periphery of the food holding compartment and an overhang adapted to overlap and engage the rim, and where the rim is provided on the tray and the overhang is provided on the lid, or vice versa, and where at least one of the rim and the overhang comprise at least one indentation, said indentation being arranged in a position within where the rim and overhang overlap, when connected,

- and where the rim and the overhang, when connected, provide a connection which will resist a pressure which is higher in the food holding compartment than outside the food holding compartment when said pressure is up to a predetermined value, and where the indentation, rim and overhang are arranged such that a pressure which is higher in the food holding compartment than outside the food holding compartment is released locally at the indentation by deflection of a part of the overhang and/or a part of the rim which will open a passage out from the food holding compartment via the indentation while overall maintaining the connection between the rim and the overhang, when food is heated in the container and said pressure exceeds a predetermined value,

- or where the indentation extends from an inward position in the food holding compartment where the rim and overhang do not engage, when connected, via a position within where the rim and overhang overlap, when connected, and to an outward position away from the food holding compartment where the rim and overhang do not engage, when connected, such that a passage out from the food holding compartment via the indentation is provided, and where the indentation is adapted to have a sufficiently small cross-section in order to on one side allow release of air, gas and/or steam via the passage, when food is heated in the container, and on another side prevent liquid from escaping via the passage.

2. A self-venting container according to claim 1, where the indentation has a smaller cross- sectional area at an inward position and a larger cross-sectional area at a position within where the rim and overhang overlap, when connected.

3. A self-venting container according to claim 1 or 2, where the indentation is oblong and placed with a longitudinal axis perpendicular or slanted relative to the rim or the overhang.

4. A self-venting container according to any preceding claim, where the rim or the 5 overhang comprises a plurality of indentations, preferably arranged equidistantly.

5. A self-venting container according to any preceding claim, where a plurality of indentations are provided in the rim and/or the overhang by, in a direction along the circumference of said rim and/or overhang, alternatingly decreasing and increasing the

10 width of the rim and/or the overhang in a way where the rim and the overhang in a number of areas are engaged and in a number of areas have a mutual distance.

6. A self-venting container according to any preceding claim, where the overhang is arranged to snap-on engage the rim at both an inward side facing the food holding

15 compartment as well as an outward side.

7. A self-venting container according to any preceding claim, where the rim is arranged on the tray and a sealing film is attached to the rim, and overlaps and closes any indentation present in the rim, said sealing film being arranged such that food in the food holding

20 compartment is enclosed and sealed also when the lid is removed.

8. A self-venting container according to any preceding claim, where the sealing film is adapted to at least partly release from the rim when subjected to heating.

25 9. A self-venting container according to any preceding claim, where the connection between the rim and the overhang as well as the size and number of indentations are adapted to resist pressure exerted by food enclosed in a food holding compartment, said pressure being exerted due to movements during handling and/or transport.

30 10. A self-venting container according to any preceding claim, where the connection between the rim and the overhang as well as the size and number of indentations are adapted according to the viscosity of the food enclosed in a food holding compartment.

11. A self-venting container according to any preceding claim, where the connection 35 between the rim and the overhang as well as the size and number of indentations are adapted according to the amount of steam released by the food enclosed in a food holding compartment during heating.

12. A self-venting container according to any preceding claim, where the at least one food holding compartment is arranged such that the tray includes at least one section which may be gripped without touching the food holding compartment while removing the lid after heating.

13. A self-venting container according to any preceding claim, where the lid is hinged to the tray.

14. A self-venting container according to any preceding claim, where the lid is made from a polymeric material, preferably at least partly crystallised polyethylene terephthalate

(PET), polypropylene (PP), or a laminate comprising polypropylene (PP) and ethylene vinyl alcohol polymer (EVOH).

15. A self-venting container according to any preceding claim, where the tray is made from a polymeric material, preferably at least partly crystallised polyethylene terephthalate

16. A self-venting container according to any preceding claim, where the tray and/or the lid is manufactured in a process comprising rotary moulding melt to mould process, die casting, injection moulding or thermoforming.

17. A self-venting container according to any preceding claim, where the food is packaged in the container while being either cold, temperate or heated.

18. A self-venting container according to any preceding claim, where the food comprises a ready-made dish, soup, sauce or a plurality of elements of a ready-made dish.

19. A lid adapted to be connected to a tray, the lid and the tray being adapted for holding food, including while the food is heated, where the tray has at least one food holding compartment and the lid is adapted to close the food holding compartment such that food placed in the food holding compartment is enclosed when said lid is connected to the tray, and where the tray and the lid are mutually connectable by comprising a rim extending around a periphery of the food holding compartment and an overhang adapted to overlap and engage the rim, and where the rim is provided on the tray and the overhang is provided on the lid, and where the lid comprises at least one indentation in the overhang, said indentation being arranged in a position within where the rim and overhang overlap, when connected, - and where the rim and the overhang, when connected, provides a connection which will resist a pressure which is higher in the food holding compartment than outside the food holding compartment when said pressure is up to a predetermined value, and where the indentation and overhang are arranged such that a pressure which is higher in the food holding compartment than outside the food holding compartment will be released locally at the indentation by deflection of a part of the overhang and/or a part of the rim, which will open a passage out from the food holding compartment via the indentation while overall maintaining the connection between the rim and the overhang, when food is heated in the container and said pressure exceeds a predetermined value,

20. A tray adapted to have a lid connected, where the tray and the lid are adapted for holding food, including while the food is heated, the tray having at least one food holding compartment and at least one lid being adapted to close the food holding compartment such that food placed in the food holding compartment is enclosed when said lid is connected to the tray, where the tray and the lid are mutually connectable by comprising a rim extending around a periphery of the food holding compartment and an overhang adapted to overlap and engage the rim, and where the rim is provided on the tray and the overhang is provided on the lid, and where the tray comprises at least one indentation in the rim, said indentation being arranged in a position within where the rim and overhang overlap, when connected,

- and where the rim and the overhang, when connected, provide a connection which will resist a pressure which is higher in the food holding compartment than outside the food holding compartment when said pressure is up to a predetermined value, and where the indentation and rim are arranged such that a pressure which is higher in the food holding compartment than outside the food holding compartment is released locally at the indentation by deflection of a part of the overhang and/or a part of the rim which will open a passage out from the food holding compartment via the indentation while overall maintaining the connection between the rim and the overhang, when food is heated in the container and said pressure exceeds a predetermined value,

- or where the indentation extends from an inward position in the food holding compartment where the rim and overhang do not engage, when connected, via a position within where the rim and overhang overlap, when connected, and to an outward position away from the food holding compartment where the rim and overhang do not engage, when connected, such that a passage out from the food holding compartment via the indentation is provided, and where the indentation is adapted to have a sufficiently small cross-section in order to on one side allow release of air, gas and/or steam via the indentation, when food is heated in the container, and on another side prevent liquid from escaping via the passage.

21. Use of a container, tray or lid according to any of the preceding claims for heating food in means of transportation such as an air plane, a ship, a bus or a train.