GB2566531A

GB2566531A - Container and method of manufacture

Info

Publication number: GB2566531A
Application number: GB1715001.2A
Authority: GB
Inventors: Reed Harry
Original assignee: Reed Thermoformed Packaging Ltd
Current assignee: Reed Thermoformed Packaging Ltd
Priority date: 2017-09-18
Filing date: 2017-09-18
Publication date: 2019-03-20
Anticipated expiration: 2037-09-18
Also published as: GB201715001D0; GB2566531B

Abstract

A container comprises sidewall (12, Figure 1) extending around the perimeter of base (11) to define an open cavity (13). The sidewall terminates in rim (30) extending outward of the cavity and having a tear line (20) extending at least partially around the rim to define an indented inner rim portion 31 and a complementary outer rim portion 32. A cover (40, Figure 5) may be attached by heat sealing to raised peripheral portions 31a, 32a of both the inner 31 and outer 32 rim portions such that when the outer rim portion is detached from the inner rim portion along the tear line the seal with the inner rim portion is broken and the cover (40) remains attached to the outer rim portion 32 to define a lid for the remainder of the container. The lid may be re-attached such that complementary indents on the lid pass over the indents on the rim of the remainder of the container. Portion 32a may be raised to a greater extent than portion 31a. The tear line may have a sinusoidal, scalloped, triangular, saw-tooth or rectangular wave-form of amplitude 1-20mm and wavelength of 1-30mm.

Description

CONTAINER AND METHOD OF MANUFACTURE

The present invention relates to a container and a method of manufacturing a container.

One conventional type of packaging is a container containing an item and a cover in the form of a plastic film sealed over the top of the container to create a hermetically sealed environment. Such packaging is typically (but not exclusively) used for food items, such as raw meat, salads and ready meals.

Such packaging may be manufactured by a packaging manufacturer as an open container (i.e. without a lid) and sold to e.g. food producers. A food producer will then fill the container with one or more food items and seal it with a cover in the form of a plastic film. Once sold to a consumer, the consumer will typically either peel off the cover if a peel tab is provided, or puncture and tear open the cover to access the one or more food items inside the container.

The problem with these conventional containers is that once the cover has been partially or completely removed, the container is not easily re-sealable. If a consumer has not used up or eaten all the contents of the container, the consumer will need to find another material to cover the open container (e.g. cling film or aluminium foil), or transfer the leftover food items to another container, e.g. one with a lid, or leave the food items exposed to the air where they will spoil more quickly. Furthermore, any information printed on the cover may be lost, e.g. branding, instructions for use, allergen warnings, or the expiry date.

Other containers such as clamshell containers consist of two halves (i.e. a body and a lid) joined by a hinge. Such containers are typically formed from a single sheet of plastic, i.e. both halves and the hinge are formed integrally (and thus the hinge is a living hinge). To close the container, one half of the container is folded over the other half of the container at the hinge. Locking features may be provided on both halves of the container that use e.g. an interference fit to keep the two halves together. However, such containers are bulky to store in their open state, as they require double the footprint compared to a container without a clamshell lid. Typically, double the amount of material is also required to manufacture a clamshell container compared to non-clamshell container.

WO2014/202762A1 discloses a container comprising a discontinuous die-cut line that circumferentially extends partially around the rim of the container. A cover in the form of a lidding film is adhered to an outer and inner portion of the rim, across the die-cut line, to seal the contents inside. During or before sealing the cover, the rim is broken at the die-cut line. To open the container, the user pulls on the outer portion of the rim to peel off the cover from the inner portion of the rim, while leaving the cover attached to the outer portion of the rim. The torn outer portion of the rim, together with the attached cover, form a lid that can be used to re-close the container. To keep the lid in place after re-closing the lid, the rim further comprises bulges that are divided by the die-cut line into two parts. These bulges are slightly compressed when die-cutting the die-cut line to form mutually co-operating tabs. When the opened lid is placed back over the container, the lid can be kept in the re-closed position by pushing the tabs together.

A problem with this container is that because the tabs of each pair are formed from the same bulge, the compression provided by the die-cutting process is necessary to allow the tabs to co-operate. This limits the processes available to manufacture the container, and the reliability of the grip between the tabs is dependent on the reliability of the amount of compression produced by the diecutting process. The available grip between the tabs to keep the lid closed is also limited because the overlapping area of the co-operating tabs is typically small. Furthermore, this container requires a larger rim in order to accommodate the bulges.

Another form of packaging is sold in the form of adjacent containers that are joined together by a perforated line, e.g. multi-pack packaging. Each container is sealed by separate covers that do not cover the perforated line. This allows the user to separate the multi-pack into separate, discrete containers that remain sealed until the user decides to open them. In contrast to the container disclosed in WO 2014/202762 Al, the perforated line of the multi-pack packaging defines an outer peripheral edge of the rim of each container (when the containers are separated), rather than dividing the rim of each container into an inner rim portion and an outer rim portion. Thus, such multi-pack packaging does not have the advantage of being able to provide a re-closable lid formed from the cover attached to a portion of the rim.

An objective of the present invention is to provide a container that can be more reliably and effectively re-closed than the above-described containers.

According to a first aspect of the invention, there is provided a container comprising:

a base and a sidewall extending around the perimeter of the base to define an open cavity, the sidewall terminating in a rim extending outward relative to the cavity; and a tear line circumferentially extending at least partially around the rim to define an indented inner rim portion between an inner peripheral edge of the rim and the tear line, and a complementary outer rim portion between an outer peripheral edge of the rim and the tear line. Thus, the complementary outer rim portion may be indented.

The term indent and its variants (indents, indented etc.) are equivalent to the term notch and its equivalents (notches, notched etc.).

The container allows the rim to be pulled apart at the tear line to open the container. In use (with a cover attached to the rim), the outer rim portion and the attached cover form a lid that can be placed back over the container. The container can then be mechanically re-closed by pushing the outer rim portion down and past the inner rim portion. The indents of the inner rim portion and the complementary outer rim portion help to block the outer rim portion from moving back past the inner rim portion in the opening direction, thereby effectively holding the container in the re-closed position. Furthermore, by using the original cover as part of the re-closable lid, information on the lid such as branding information, instructions for use, allergen warnings, expiry dates and ingredients data are left intact for the user to refer to. The container, with or without the cover, is also conveniently stackable, even with conventional containers.

The base and the rim are not limited to being a particular shape. The base and the rim may be, for example, circular, rectangular, square or another regular polygon (e.g. pentagon, hexagon), or an irregular shape. The outer perimeter of the rim does not need to be the same shape as the inner perimeter of the rim. Furthermore, the shape of the base does not need to be the same shape as the rim. For example, the base could have a square perimeter and the rim could have a circular outer perimeter. This is because the indents are defined by the tear line, rather than the shape of the base or the rim.

Preferably, the container defines at least one cavity. In certain embodiments, the container defines two cavities. In other embodiments, the container defines three cavities. In some embodiments, the container defines four cavities. This is particularly useful where different products are to be supplied in the container, e.g. different foodstuffs such as different fruits, e.g. blueberries, raspberries, strawberries, pineapple and mango.

The indented inner rim portion may comprise at least one indent at the tear line. One indent is sufficient to enable the lid to be re-closed securely. To hold the lid in the re-closed position more securely, the inner rim portion preferably comprises a plurality of indents at the tear line. The inner rim portion preferably comprises at least 3 indents at the tear line, more preferably 5 indents, 10 indents, 15 indents or 20 indents. Preferably, the inner rim portion comprises 1000 indents or less, more preferably 900 indents or less, 800 indents or less, 700 indents or less, 600 indents or less, or 500 indents or less.

Preferably, at least one indent has a curved, triangular, sawtooth, rectangular, or square profile, i.e. at least one indent has a profile selected from the group consisting of curved, triangular, sawtooth, rectangular, or square. The term curved profile is not limited to profiles that are completely curved, but also includes profiles that have a combination of curves and straight lines, e.g. two parallel lines joined by an arc at one end.

Preferably, each indent has one of the following profiles: curved, triangular, sawtooth, rectangular, or square. For the avoidance of doubt, each indent does not need to have the same profile. The indented inner rim portion could comprise indents of a mixture of different profiles. For example, the indented inner rim portion could comprise indents having a curved profile and other indents having a triangular profile. However, each indent may have the same profile to make the container easier to manufacture.

Each indent extends in the plane of the rim and can be described as having a depth in a radial direction or a direction substantially toward the cavity, and as having a width in a circumferential direction or a direction substantially parallel to the cavity.

Preferably, each indent has a depth (i.e. a maximum depth) of at least 1 mm. Preferably, each indent has a depth of at least 2 mm. Preferably, each indent has a depth of at least 3 mm. Preferably, each indent has a depth of at least 4 mm. Preferably, each indent has a depth of at least 5 mm.

Preferably, each indent has a depth (i.e. a maximum depth) of 20 mm or less. Preferably, each indent has a depth of 15 mm or less. Preferably, each indent has a depth of 10 mm or less. Preferably each indent has a depth of 5 mm or less.

Preferably, each indent has a width (i.e. a maximum width) of at least 1 mm. Preferably, each indent has a width of at least 2 mm. Preferably, each indent has a width of at least 3 mm. Preferably, each indent has a width of at least 4 mm. Preferably, each indent has a width of a least 5 mm. Preferably, each indent has a width of at least 10 mm. Preferably, each indent has a width of at least 15 mm.

Preferably, each indents has a width (i.e. maximum width) of 30 mm or less. Preferably, each indent has a width of 25 mm or less. Preferably, each indent has a width of 20 mm or less.

Preferably, the combined profile of at least two adjacent indents is a corrugated profile (i.e. a wavy line).

Preferably, the combined profile of at least two adjacent indents is a periodic waveform. In particular, the combined profile of at least two adjacent indents is preferably a sinusoidal waveform, a scalloped waveform, a triangle waveform, a saw-tooth waveform, a rectangle waveform, or a square waveform. A scalloped waveform can be formed from adjacent indents having a semicircular profile, which is an example of a curved profile.

For adjacent indents having a combined profile that is a periodic waveform, the size of the indents can be described using waveform terminology, e.g. amplitude and wavelength. The amplitude corresponds to the peak-to-trough distance and the wavelength corresponds to the peak-to-peak distance. As such, the amplitude of the waveform corresponds to the depth of each indent and the wavelength of the waveform corresponds to the width of each indent.

Preferably, the amplitude of the waveform is at least 1 mm. Preferably, the amplitude of the waveform is at least 2 mm. Preferably, the amplitude of the waveform is at least 3 mm. Preferably, the amplitude of the waveform is at least 4 mm. Preferably, the amplitude of the waveform is at least 5 mm.

Preferably, the amplitude of the waveform is 20 mm or less. Preferably, the amplitude of the waveform is 15 mm or less. Preferably, the amplitude of the waveform is 10 mm or less. Preferably, the amplitude of the waveform is 5 mm or less.

Preferably, the wavelength of the waveform is at least 1 mm.

Preferably, the wavelength of the waveform is at least 2 mm.

Preferably, the wavelength of the waveform is at least mm.

Preferably, the wavelength of the waveform is at least 4 mm.

Preferably, the wavelength of the waveform is at least 5 mm.

Preferably, the wavelength of the waveform is at least 10 mm.

Preferably, the wavelength of the waveform is at least 15 mm.

Preferably, the wavelength of the waveform is 30 mm or less.

Preferably, the wavelength of the waveform is 25 mm or less. Preferably, the wavelength of the waveform is 20 mm or less.

Single indents or groups of indents may be separated by non-indented portions at the tear line.

In certain embodiments, the tear line is a perforated line comprising bridging elements joining the inner rim portion to the outer rim portion. In this way, the rim will tear (break) at the tear line when the outer rim portion is separated from the inner rim portion via breaking of the bridging elements.

In certain embodiments, the portion of the rim at the tear line is weaker than the remaining portion of the rim. Such a line of weakness in the rim could take the form of a groove or a scored line where the rim is thinner along the tear line compared to the remaining portion of the rim.

In certain embodiments, the tear line circumferentially extends around the whole rim to form a closed loop. This allows the outer rim portion (and the attached cover, in use) to be completely separated from the inner rim portion to form a removable, yet re-closable lid. However, if the user does not wish to completely remove the lid from the container, then a portion of the tear line can be left unbroken when opening the container for the first time. The unbroken portion can then act as a hinge about which the lid can pivot.

In certain embodiments, the tear line circumferentially extends partially around the rim. In this way, the remaining circumferential portion of the rim that does not contain the tear line can act as a living hinge (i.e. a hinge made from the same material as the inner and outer rim portions). In use, the outer rim portion can pivot about the living hinge when opening and closing the lid. The living hinge helps the lid to be re-closed more easily and helps the lid to stay securely on the container once the lid has been re-closed.

Preferably, the length of the tear line is at least 50% of the length of the inner peripheral edge of the rim. In certain embodiments, the length of the tear line is at least 60% of the length of the inner peripheral edge of the rim. In other embodiments, the length of the tear line is at least 70% of the length of the inner peripheral edge of the rim. In some embodiments, the length of the tear line is at least 80% of the length of the inner peripheral edge of the rim. In certain embodiments, the length of the tear line is at least 90% of the length of the inner peripheral edge of the rim.

The outer rim portion may comprise an outer raised surface circumferentially extending around the outer rim portion. The outer raised surface preferably circumferentially extends around the whole of the outer rim portion to form a closed loop. The outer raised surface acts as a flange for attaching a cover (in use). The outer raised surface conveniently raises the cover away from the tear line to minimise the risk of breaking the cover when separating the rim at the tear line.

The inner rim portion may also comprise an inner raised surface circumferentially extending around the inner rim portion. The inner raised surface preferably circumferentially extends around the whole of the inner rim portion to form a closed loop. The inner raised surface also acts as a flange for attaching a cover (in use).

The outer raised surface and the inner raised surface define a channel therebetween (i.e. a channel a recess - is defined between the outer raised surface and the inner raised surface). The tear line is preferably located between the outer raised surface and the inner raised surface, at the base of the channel. This configuration (i.e. a double raised surface with channel) provides strength to the rim of the container and provides a stronger (more rigid) portion of the rim that enables the tear line to be created more efficiently.

The cover is preferably attached to both the outer raised surface and the inner raised surface. By attaching the cover to both the outer raised surface and the inner raised surface, a double seal is formed. The double seal minimises the risk of exposing the inside of the cavity to the outside environment, should one of the seals fail. The inner seal will also keep the cavity sealed if the rim separates at the tear line prematurely.

In certain embodiments, the outer raised surface is higher than the inner raised surface relative to the base of the container.

Alternatively, the outer raised surface is at the same level as the inner raised surface relative to the base of the container, or the outer raised surface may be at a lower level than the inner raised surface relative to the base of the container. The latter configuration would help to provide a tighter seal over the cavity when the lid has been re-closed (in the case of a flexible cover material).

The container may further comprise a cover attached to the outer rim portion and extending across the cavity. This allows an item to be enclosed in the cavity and, in combination with the outer rim portion, forms a lid that can be re-closed over the container. In the case that the outer rim portion has an outer raised surface, the cover is preferably attached to the outer raised surface.

The cover may be attached to both the outer rim portion and the inner rim portion to form a double seal, the advantages of which are explained above. In the case that the inner rim portion has an inner raised surface, the cover is preferably attached to the inner raised surface.

Preferably, the attachment between the cover and the outer rim portion (or outer raised surface) is stronger than the attachment between the cover and the inner rim portion (or inner raised surface). For example, in the case of a heat sealed cover, less heat and pressure could be used to seal the cover to the inner rim portion (or inner raised surface) compared to the outer rim portion (or outer raised surface). This helps to ensure that the cover detaches from the inner rim portion (or inner raised surface) while the cover remains attached to the outer rim portion (or outer raised surface).

Preferably, the cavity is hermetically sealed by the cover when the cover is first attached. This provides an initial safe environment for storing food items, for example.

In certain emboduments, the cover is a film, e.g. a plastic film. In other embodiments, the cover is made from other materials such as metal, wood, paper or cardboard. The cover may be transparent to allow the contents of the container to be seen from outside the container. The cover may be opaque and/or coloured to allow for information (e.g. branding) to be displayed on the cover. The cover is preferably made from a flexible material to facilitate opening and re-closing of the container.

The container is preferably made of a flexible material. This allows the container to be deformed, which allows the outer rim portion to be pushed down past the inner rim portion more easily when re-closing the container. Furthermore, slight lateral movement between the outer rim portion and the inner rim portion when in the re-closed position increases the blocking effect of the indents so that the lid is held more securely in the re-closed position.

The container may be made of plastic, e.g. polyethylene terephthalate (PET) or polypropylene (PP), or a biopolymer such as polylactic acid (PLA), which can be easily formed into a container shape by known methods, e.g. thermoforming or injection moulding. The container may also be made of other materials such as metal, wood or cardboard. Food-safe materials may be used for a container for storing food items.

The cavity may contain an item, e.g. a food item, with or without the cover. The cavity may also contain a non-food item e.g. washing tablets, dishwasher tablets. Thus, the container is able to store items and conveniently keep them securely in storage even once the container has been opened.

According to another aspect of the invention, there is provided a method of manufacturing a container comprising:

manufacturing a container comprising a base and a sidewall extending around the perimeter of the base to define an open cavity, the sidewall terminating in a rim extending outward relative to the cavity; and forming a tear line circumferentially extending at least partially around the rim to define an indented inner rim portion between an inner peripheral edge of the rim and the tear line, and a complementary outer rim portion between an outer peripheral edge of the rim and the tear line.

The container may be manufactured by thermoforming a plastic sheet. Other methods such as injection moulding of plastic granules may also be used.

The tear line may be formed by die-cutting, e.g. by using a die having an indented edge.

A cover that extends across the open cavity, preferably the across the whole of the open cavity may be attached to the outer rim portion.

Preferably, the cover is further attached to the inner rim portion.

The cover may be attached to the outer rim portion (and the inner rim portion) by heat sealing (i.e. applying heat and/or pressure), RF (radio frequency) welding, ultrasonic welding or other types of welding.

An item may be placed into the cavity before attaching the cover.

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1	is a perspective view of a first embodiment of a container in accordance with the invention.
Figure 2	is a plan view of the container shown in Figure 1.
Figure 3	is a partial plan view of the container shown in Figure 1.
Figure 4	is a perspective view of the container shown in Figure 1 during use.
Figure 5	is a side view of the container shown in Figure 4.
Figure 6	is a partial plan view of the container shown in Figure 1 during use.
Figures 7a-7d	are partial sectional views of the container shown in Figure 1 during use.
Figure 8	is a perspective view of a second embodiment of a container in accordance with the invention.
Figure 9	is a plan view of the container shown in Figure 8.
Figure 10	is a partial plan view of the container shown in Figure 8.
Figure 11	is a perspective view of the container shown in Figure 8 during use.
Figure 12	is a side view of the container shown in Figure 11
Figure 13	is a partial plan view of the container shown in Figure 8 during use.

In the drawings, like parts are denoted by like reference numerals.

Figures 1 and 2 show a container 10. The container 10 has a base 11 and a sidewall 12 that extends around the perimeter of the base 11 to define an open cavity 13. The sidewall 12 terminates in a rim 30 that extends outward relative to the cavity 13. The rim 30 is rectangular in shape with rounded corners (i.e. the inner perimeter and the outer perimeter of the rim 30 are substantially rectangular with rounded corners). The open cavity 13 is divided into six sub-cavities that are suitable for holding an individual product such as a muffin.

A tear line 20 circumferentially extends partially around the rim 30. A partial view of the tear line 20 is shown in Figure 3. The tear line 20 defines two portions of the rim 30 - an indented inner rim portion 31 between the inner peripheral edge 36 of the rim and the tear line 20, and a complementary outer rim portion 32 between the outer peripheral edge 37 of the rim 30 and the tear line 20. The inner peripheral edge 36 of the rim refers to the edge of the rim 30 closest to the cavity 13 in a radial direction, and the outer peripheral edge 37 of the rim 30 refers to the edge of the rim 30 furthest away from the cavity 13 in a radial direction.

The shape of the inner rim portion 31 and the shape of the outer rim portion 32 are defined by the path of the tear line 20. As a result, the outer rim portion 32 is complementary to the inner rim portion 31, i.e. the shape of the outer rim portion 32 at the tear line 20 fits into the shape of the inner rim portion 31 at the tear line 20.

The indented inner rim portion 31 comprises indents 33 located at the tear line 20. The profile of the indents 33 is determined by the path of the tear line 20. In this embodiment, the tear line 20 is a wavy line, in particular a sinusoidal waveform. Thus, the indents 33 have a curved profile, with adjacent indents having a sinusoidal profile in combination. The maximum depth of each indent 33 (i.e. the amplitude of the sinusoidal waveform) is about 1 mm and the width of each indent (i.e. the wavelength of the sinusoidal waveform) is about 6.5 mm.

The tear line 20 provides a line at which the rim 30 will tear when the outer rim portion 32 is moved relative to the inner rim portion 31 (e.g. when the outer rim portion 32 is pulled transverse to the inner rim portion 31). In this embodiment, the tear line is a perforated line, i.e. the inner rim portion 31 and the outer rim portion 32 are joined together by bridging elements 21, with gaps between adjacent bridging elements.

The outer rim portion 32 includes an outer raised surface 32a that projects out of the plane of the rim 30 and acts as a flange for attaching a cover. The outer raised surface 32a circumferentially extends around the whole of the outer rim portion 32 to form a closed loop.

The inner rim portion 31 includes an inner raised surface 31a that projects out of the plane of the rim 30 and also acts as a flange for attaching a cover 40 (cover 40 is not shown in Figures 1-3). The inner raised surface 31a circumferentially extends around the whole of the inner rim portion 31 to form a closed loop.

A channel 38 is defined between the outer raised surface 32a and the inner raised surface 31a. The tear line 20 is located in between the outer raised surface 32a and the inner raised surface 31a at the base of the channel 38. The outer raised surface 32a is higher than the inner raised surface 31a relative to the base 11.

A cover 40 extends across the cavity 13 to form an enclosed cavity. The cover 40 is a thin film and is transparent to show the contents inside the container. The cover 40 is heat sealed all the way around the outer raised surface 32a and is also heat sealed all the way around the inner raised surface 31a. Thus, the cover 40 is sealed to the rim 30 on both sides of the tear line 20 to form a double seal around the cavity 13. This double seal is more reliable than a single seal and minimises the risk of the cavity 13 becoming exposed to the outside environment. For example, if one of the seals breaks, the cavity 13 will remain hermetically sealed by the remaining seal, or if the tear line 20 accidently breaks before the user intends to open the container, the inner seal will keep the cavity 13 hermetically sealed.

The strength of the seal between the cover and the inner raised surface 31a is enough to withstand general transport and handling of the container without failing, but is weak enough to allow a user to peel off the cover 40 from the inner raised surface 31a by hand.

The seal between the cover 40 and the inner raised surface 31a is weaker than the seal between the cover 40 and the outer raised surface 32a. This helps to ensure that the cover 40 detaches from inner raised surface 31a while remaining attached to the outer raised surface 32a when the container is opened for the first time.

In use, an item is placed in the open cavity 13 of the container 10. The cover 40 is then heat sealed to the outer raised surface 32a and the inner raised surface 31a by applying heat and pressure to seal the item inside the cavity 13. Because the outer raised surface 32a is higher than the inner raised surface 31a relative to the base, the act of heat sealing the cover (i.e. applying pressure) pushes the outer raised surface 32a relative to the inner raised surface 31a.

To open the container 10, the user (typically an end consumer, e.g. a customer of a retailer) pulls the outer rim portion 32 away from the inner rim portion 31. To make this operation easier, the rim 30 has a pull tab 35 integrally formed with the outer rim portion 32 and extending outwards relative to the cavity 13 to provide a larger surface area for the user to hold on to when pulling the outer rim portion 32.

As explained above, the seal between the cover 40 and the inner raised surface 31a is weaker than the seal between the cover 40 and the outer raised surface 32a. Thus, when the outer rim portion 32 is separated from the inner rim portion 31, the cover 40 remains attached to the outer raised surface 32a while detaching from the inner raised surface 31a. The cover 40 in combination with the outer rim portion 32 to which the cover 40 is attached forms a lid 41.

Figures 4 and 5 show container 10 comprising the lid 41 (i.e. the cover 40 attached to the outer rim portion 32) in an open configuration. The cover 40 has been detached from the inner raised surface 31a, thereby allowing access to the items in the cavity 13.

As described above, the tear line 20 circumferentially extends partially around the rim 30. In use, the remaining circumferential portion of the rim 30 that does not contain the tear line 20 acts as a hinge 39, in particular a living hinge (i.e. a hinge made from the same material as the inner and outer rim portions). In use, the outer rim portion 32 can pivot about the hinge 39 when opening and closing the lid 41. The hinge 39 helps the lid 41 to be re-closed more easily and helps the lid 41 to stay securely on the container 10 once the lid 41 has been re-closed.

Figure 6 shows a partial view of the rim 30 when the container 10 is in the re-closed configuration. To re-close the container 10, the lid 41 is placed back over the cavity 13 and pushed past the inner rim portion 31 in the closing direction. This results in the outer rim portion 32 slipping past the inner rim portion 31 so that the inner rim portion 31 lies between the outer rim portion 32 and the cover 40. In particular, the indents 33 of the inner rim portion 31 overlap the complementary outer rim portion 32. This helps to prevent the outer rim portion 32 from slipping back past the inner rim portion 31 in the opening direction when the container 10 is at rest or lightly handled by the user. The container is thereby effectively re-closed.

Figures 7a to 7d show a sectional view of the rim 30 and illustrate the change in the configuration of the rim 30 while the container 10 is in use.

Figure 7a shows the rim 30 in its unbroken configuration. The outer rim portion 32 is joined to the inner rim portion 31 by bridging elements 21. The outer raised surface 32a is higher than the inner raised surface 31a relative to the base 11.

Figure 7b shows the rim 30 after the cover 40 has been attached. The cover 40 is attached to both the outer raised surface 32a and the inner raised surface 31a. The outer raised surface 32a and the inner raised surface 31a are at the same height relative to the base 11 and the bridging elements 21 have been broken.

Figure 7c shows the rim 30 after the cover 40 has detached from the inner raised surface 31a. The cover 40 remains attached to the outer raised surface 32a to form the lid 41.

Figure 7d shows the rim 30 after the container has been re-closed. The lid 41 has been placed back over the container 10 and the inner rim portion 31 lies between the outer rim portion 32 and the cover 40. The indents 33 of the inner rim portion 31 overlap with the complementary outer rim portion 32 to keep the lid 41 in the re-closed position.

To re-open the container 10, the user pulls the outer rim portion 32 away from the inner rim portion 31 in the same manner as opening the container for the first time. This causes the outer rim portion to slip past the inner rim portion 31 so that the lid 41 is opened and the items inside the cavity 13 can be accessed again.

The container can be re-opened and re-closed in the same manner as many times as is necessary.

Figures 8 and 9 show a second embodiment of container 10. Many of the features and functionality of the second embodiment are the same as the first embodiment and thus will not be described again in detail here.

The container 10 of the second embodiment comprises the same elements as the first embodiment base 11, sidewall 12, cavity 13, rim 30, tear line 20, indented inner rim portion 31 with inner raised surface 31a, complementary outer rim portion 32 with outer raised surface 32a, and channel 38 in which the tear line 20 is located. In contrast to the first embodiment, the base 11 and the rim 30 are circular in shape. Furthermore, tear line 20 extends circumferentially extends around the whole of the rim 30. Container 10 of the second embodiment does not include a pull tab 35.

Figure 10 shows a partial plan view of the container 10. The tear line 20 follows a sinusoidal path that circumferentially extends around the whole rim 30 to form a closed circular loop. The indented inner rim portion 31 comprises indents 33 that have a curved profile. The tear line 20 is a perforated line comprising bridging elements 21 joining the inner rim portion 31 and the outer rim portion 32.

The container 10 of the second embodiment is used in the same way as for the first embodiment,

i.e. a cover 40 is heat sealed to both the outer raised surface 32a and the inner raised surface 31a to form a double seal; the container 10 is then opened for the first time by lifting the outer rim portion 32 away from the inner rim portion 31 to form a lid 41 comprising the cover 40 still attached to the outer raised surface 32a.

Figures 11 and 12 show the container 10 of the second embodiment in an open configuration where the lid 41 is completely separated from the container 10 (i.e. the bridging elements 21 have all been broken). To re-close the container 10, the lid 41 is pushed down over the container 10, such that the indented inner rim portion 31 slips past the complementary outer rim portion 32 to lie between the outer rim portion 32 and the cover 40.

Figure 13 shows the container 10 in the re-closed configuration. As for the first embodiment, the indented inner rim portion 31 overlaps with the complementary outer rim portion 32 to keep the lid 41 in the re-closed position. Because the container 10 and the lid 41 of the second embodiment are generally circular, the lid 41 can be advantageously twisted about the container 10 when in the re closed position in order to increase the overlap between the indented inner rim portion 31 and the complementary outer rim portion 32.

A method of manufacturing the container 10 of either the first or second embodiment will now be described.

First the base 11, sidewall 12 and rim 30, including the inner raised surface 31a and outer raised surface 32a are formed by thermoforming a single sheet of plastic. The outer raised surface 32a is formed higher than the inner raised surface 31a relative to the base 11. Methods of thermoforming a plastic sheet to form an open container are well known in the art and will not be described in further detail here.

Next, the tear line 20 is created by die-cutting a perforated line into the rim 30. A die having a sinusoidal edge is used to cut the perforated tear line 20, resulting in indents 33 having a curved profile, with adjacent indents forming a sinusoidal waveform in combination.

Next, an item to be enclosed is placed in the open cavity 13. A cover 40 is then placed over the container 10 and heat sealed to the outer raised surface 32a and the inner raised surface 31a under heat and pressure. During the sealing operation, the pressure applied to the cover 40 causes the outer raised surface 32a to be pushed relative to the inner raised surface 31a (due to their difference in heights). This sealing operation can be carried out using known heat sealer machines, for example.

Various modifications to the method will be apparent to those skilled in the art. For example, to produce indents having different profiles, a die with a different shaped edge can be used, e.g. a die having a sawtooth edge will produce indents having a sawtooth profile. Other methods of forming the container may also be used, e.g. injection moulding.

Reference signs

- container

- base

- sidewall

- cavity

- tear line

- bridging element

- rim

- inner rim portion

31a - inner raised surface

- outer rim portion

32a - outer raised surface

- indent

- pull tab

36 - inner peripheral edge (of rim 30)

- outer peripheral edge

- channel

- hinge

- cover

41 - lid

Claims

1. A container comprising:

a base and a sidewall extending around the perimeter of the base to define an open cavity, the sidewall terminating in a rim extending outward relative to the cavity; and a tear line circumferentially extending at least partially around the rim to define an indented inner rim portion between an inner peripheral edge of the rim and the tear line, and a complementary outer rim portion between an outer peripheral edge of the rim and the tear line.

2. A container according to claim 1, wherein the inner rim portion comprises at least one indent at the tear line.

3. A container according to claim 1, wherein the inner rim portion comprises a plurality of indents at the tear line.

4. A container according to any one of claims 1 to 3, wherein the inner rim portion comprises at least 3 indents at the tear line.

5. A container according to any one of claims 1 to 4, wherein at least one indent has a curved, triangular, sawtooth, rectangular, or square profile.

6. A container according to any one of the preceding claims, wherein each indent has one of the following profiles: curved, triangular, sawtooth, rectangular, or square.

7. A container according to any one of claims 3 to 6, wherein the combined profile of at least two adjacent indents is a periodic waveform.

8. A container according to any one of claims 3 to 7, wherein the combined profile of at least two adjacent indents is a sinusoidal waveform, a scalloped waveform, a triangle waveform, a saw-tooth waveform, a rectangle waveform, or a square waveform.

9. A container according to any one of the preceding claims, wherein the tear line is a perforated line comprising bridging elements joining the inner rim portion to the outer rim portion.

10. A container according to any one of claims 1 to 8, wherein the portion of the rim at the tear line is weaker than the remaining portion of the rim.

11. A container according to any one of the preceding claims, wherein the tear line circumferentially extends around the whole rim to form a closed loop.

12. A container according to any one of claims 1 to 10, wherein the tear line circumferentially extends partially around the rim.

13. A container according to claim 12, wherein the rim comprises a hinge portion configured to act as a pivot between the inner rim portion and the outer rim portion.

14. A container according to any one of the preceding claims, wherein the outer rim portion comprises an outer raised surface circumferentially extending around the outer rim portion.

15. A container according to according to claim 14, wherein the inner rim portion comprises an inner raised surface circumferentially extending around the inner rim portion.

16. A container according to claim 15, wherein the outer raised surface is higher than the inner raised surface relative to the base of the container.

17. A container according to claim 15 or claim 16, wherein a channel is defined between the outer raised surface and the inner raised surface and the tear line is located in the channel.

18. A container according to any one of the preceding claims, further comprising a cover attached to the outer rim portion and extending across the cavity.

19. A container according to claim 18, wherein the cover is attached to the outer raised surface.

20. A container according to claim 18 or claim 19, wherein the cover is further attached to the inner rim portion.

21. A container according to claim 20, wherein the cover is attached to the inner raised surface.

22. A container according to claim 20 or claim 21, wherein the attachment between the cover and the outer rim portion is stronger than the attachment between the cover and the inner rim portion.

23. A container according to any one of claims 18 to 22, wherein the cavity is hermetically sealed.

24. A container according to any one of claims 18 to 23, wherein the cover is a plastic film.

25. A container according to any one of the preceding claims, wherein the container is made of a flexible material.

26. A container according to any one of the preceding claims, wherein the container is made of plastic.

27. A container according to any one of the preceding claims, wherein the cavity contains an item.

28. A container according to claim 27, wherein the item is a food item.

29. A method of manufacturing a container comprising:

manufacturing a container comprising a base and a sidewall extending around the perimeter of the base to define an open cavity, the sidewall terminating in a rim extending outward relative to the cavity; and forming a tear line circumferentially extending at least partially around the rim to define a indented inner rim portion between an inner peripheral edge of the rim and the tear line, and a complementary indented outer rim portion between an outer peripheral edge of the rim and the tear line.

30. A method according to claim 29, wherein the container is manufactured by thermoforming a plastic sheet.

31. A method according to claim 29 or claim 30, wherein the tear line is formed by die-cutting.

32. A method according to any one of claims 29 to 31, further comprising attaching a cover that extends across the open cavity to the outer rim portion.

33. A method according to claim 32, further comprising further attaching the cover to the inner rim portion.

34. A method according to claim 32 or claim 33, wherein the cover is attached by heat sealing.

35. A method according to any one of claims 32 to 34, wherein before or during the step of attaching the cover, the inner rim portion and outer rim portion are separated along at least a portion of the tear line.

36. A method according to any one of claims 32 to claim 35, further comprising placing an item into the cavity before attaching the cover.