GB2611048A

GB2611048A - Base structure, kit of parts and a method

Info

Publication number: GB2611048A
Application number: GB2113565.2A
Authority: GB
Inventors: Harrison Keith
Original assignee: Par Pak Europe Ltd
Current assignee: Par Pak Europe Ltd
Priority date: 2021-09-23
Filing date: 2021-09-23
Publication date: 2023-03-29
Also published as: WO2023047085A1; CA3232662A1; GB202113565D0

Abstract

The base structure 100 comprises a base volume 105 and a flange 110 defining an opening of the base volume, the flange extending from the base volume about the perimeter of the base volume; the flange comprising at least one projection 115 extending away from the base volume, which extends around a majority of the perimeter 145 of the base volume. The at least one projection may extend around 90% of the perimeter of the base volume or may extend continuously around the perimeter of the base volume. The flange may comprise at least two projections separated by a channel 150 (figure 4A). The flange may comprise a first outer projection nearest the base volume, a central projection, and a second outer projection nearest the outer perimeter of the flange, separated from each other by two channels. The channels may be of substantially equal width.

Description

BASE STRUCTURE, KIT OF PARTS AND A METHOD

Field of the Invention

The present invention relates to a base structure for a container. The invention also relates to a kit of parts comprising a film lid and the base structure and to a method.

Background to the Invention

There is a benefit in extending the period of time which perishable goods, such as food produce, remain fresh. By increasing the freshness time, the goods remain fit for use or consumption longer, reducing the risk of the goods soiling before use and being wasted. One way to increase freshness is to provide a container and affix a film lid to the container to form a hermetic seal over the container volume.

It is standard practice for goods to be placed within a container base structure with the film sealed onto a flat flange around the opening of the base structure. However, spilt goods and other contaminants can accumulate on the container flange during the packaging process with the contamination impeding or damaging the film-to-container seal integrity. It is a particular issue in food packing applications, such when the goods comprise meat and seafood or fatty, greasy or oily food products, leading to waste due to sealing malfunctions and potential food contamination due to small breaches in seal allowing transfer of oxygen and contaminants into the container.

There is further an issue in that polyethylene terephthalate (PET) film lids cannot be easily and securely affixed to the base structures made from the widely recyclable composition of mono-polyethylene terephthalate (mono-PET), reducing the recyclability of such containers.

As such, there is a need for a means to provide an improved seal between a container base structure and a film lid affixed to the container.

Objects and aspects of the present claimed invention seek to alleviate at least these problems with the prior art.

Summary of the Invention

According to a first aspect of the invention, there is provided a base structure for a container, the base structure comprising a base volume; and a flange defining an opening of the base volume, the flange extending from the base volume about the perimeter of the base volume; the flange comprising at least one projection, wherein the at least one projection extends away from the base volume, and further wherein the at least one projection extends around a majority of the perimeter of the base volume.

In this way there is provided an improved seal between the base structure and a film lid affixed to the base structure. During the packing process, a film lid can be affixed to at least a portion of the projection and any contaminants present on the flange are forced downward from the projection. In this way, contaminants are not caught underneath the film seal and there is a reduced risk of seal malfunction and container bursting. Maintaining a hermetic seal is advantageous in many applications as this prevents transfer of oxygen and contaminants into the container and leaking of container contents out of the container. An additional benefit of the improved hermetic seal is to dependably retain any modified atmosphere that a packer may insert into the filmed container to preserve the contents of the container. In this way, the improved seal reduces the risk of the contents of the base structure spoiling or otherwise soiling due to leakage of a modified atmosphere from the base structure.

Conventional heat-sealing methods, used for known base structures with flat flanges, of the same temperature and weld time can be employed and so the base structure of the present invention can be adapted easily and inexpensively into established manufacturing processes and equipment. Further, there is a reduced waste of packaging and container contents as there is a reduced risk of seal malfunction and the contents consequently soiling.

Preferably, the at least one projection extends around at least 90% of the perimeter of the base volume. More preferably, the at least one projection extends around at least 95% of the perimeter of the base volume. In this way, an improved seal is provided along the majority of the perimeter of the base volume. Still more preferably, the at least one projection extends continuously around the perimeter of the base volume. In embodiments wherein the base structure comprises at least two projections separated by a channel, a continuous channel is provided and so contaminants trapped within the channel are free to move about the channel, such as during transportation, without an undue build-up of pressure on the film lid.

Preferably, the flange comprises at least two projections separated by a channel. During the packaging process, a film lid can be affixed to at least a portion of the projection and any contaminants present on the flange are forced downward from the projection and into the channel between the projections. Any contaminants, such as contents of the base structure, which have accumulated on the flange are then trapped within the channel without interfering with the integrity of the seal.

Preferably, the flange comprises a central projection, a first outer projection located between the central projection and the base volume, and a second outer projection located between the central projection and an outer perimeter of the flange. Preferably, the central projection is separated from the first outer projection by a first channel, and further wherein the central projection is separated from the second outer projection by a second channel. In this way, three projections and two channels are provided.

When a film lid is affixed to the base structure, contaminants present on the first outer projection are forced towards the base volume and into the first channel, contaminants on the central projection are forced towards and into the first channel and second channel and contaminants present on the second outer projection are forced towards the second channel and the outer perimeter of the flange. In this way, contaminants do not interfere with the integrity of the seal and the first channel and second channel house any loose contaminants.

In some embodiments, the flange comprises at least four projections. In select embodiments, the flange comprises at least five projections.

Preferably, the first channel and the second channel are of substantially equal width. In this way, when a film lid is affixed to the flange, the contact points made between the projections and the film lid are substantially evenly spaced, improving load distribution.

Preferably, the first outer projection and the second outer projection are angled towards one another. In this way, when a film lid is affixed to the flange, a smoother contact point between the projections and the film lid can be made. Further, the contact points are closer together such that a more concentrated and stronger seal is provided.

Preferably, the first outer projection comprises a first face and a second face, the first face located closer to the base volume than the second face, wherein the angle between the normal to the flange and the first face is greater than the angle between the normal to the flange and the second face. Preferably, the second outer projection comprises a first face and a second face, the first face located closer to the outer perimeter of the flange than the second face, wherein the angle between the normal to the flange and the first face is greater than the angle between the normal to the flange and the second face. In this way, the outer faces of the outer projections, namely the first face of the first outer projection and the second face of the second outer projection, are of greater length than the inner faces of the projections, such as the second face of the first outer projection, the first face of the second outer projection and the faces of the central projection. Advantageously, a greater surface area is provided on the outer faces of the outer projections onto which a film lid can be affixed. Further, this encourages contaminants present on the projections into the first channel and the second channel.

Preferably, the two or more projections are of substantially the same height. In this way, a substantially straight seal can be formed over the two or more projections.

Preferably, the at least one projection tapers in height. Preferably, the flange extends in substantially the same plane as the opening of the base volume. In this way, a film lid affixed to the base structure can be affixed planar to the opening of the base volume, improving the load distribution over the film lid. Preferably, the flange is arranged to extend at an acute angle to a wall defining the base volume.

Preferably, the at least one projection tapers to a point. Alternatively, the at least one projection comprises a domed end. When a film lid is affixed to the at least one projection, any tapered point of a projection may dull and become domed, such as due to heat sealing.

Preferably, the at least one projection is located centrally on the flange. Alternatively, the distance between the at least one projection and the base volume is smaller than the distance between the at least one projection and the outer perimeter of the flange. In this way, there is a smaller region of the flange onto which the contents of the base volume can spill onto, such as during transportation, after a film lid is affixed to the base structure.

Preferably, the base structure comprises recyclable materials. More preferably, the base structure consists of recyclable materials. In particular, it is envisaged that the base structure comprises a plastic. Preferably the base structure comprises a recycled polyethylene terephthalate (rPET) and resin composition. The resin assists in temperature modulation of the base structure allowing lower melt temperatures for a film lid to be affixed to the base structure. The type of material is limited by the application and contents of the base structure and, in some embodiments, other materials may be employed, such as bioplastics, paper, paper-derived, chipboard, molded pulp, foam, bagasse, laminated materials, compostable materials, biodegradable materials, recycled materials and/or plastic blends or compounds. In many embodiments, it is preferred that the base structure comprises one material for ease of manufacturing and to reduce cost. Further, in many embodiments it is preferred that the base structure is formed from a single piece, with no joins, welds or assembly being required.

According to a second aspect of the invention, there is provided a kit of parts comprising a film lid and the base structure of the first aspect of the invention.

According to a third aspect of the invention, there is provided a method, the method comprising; providing the base structure of the first aspect of the invention; placing at least one product in the base volume of the base structure; and sealing the base volume with a film lid by affixing the film lid to the at least one projection.

In some embodiments, the step of affixing the film lid to the at least one projection comprises affixing with an adhesive. In some embodiments, the step of affixing the film lid to the at least one projection comprises affixing with a heat seal.

Preferably, the film lid is affixed to the tapered end of the at least one projection. Alternatively, the film lid is affixed to the tapered end of the at least one projection and to at least a portion of the outer faces of the outer projections of the at least one projection. For embodiments with a single projection, the outer faces of the outer projections are the first face and the second face of the projection. For embodiments with two or more projections, the outer faces of the outer projections are the first face of the first outer projection and the first face of the second outer projection.

In some embodiments, the method further comprises the step of introducing a modified atmosphere into the base volume prior to sealing the base volume with a film lid by affixing the film lid to the at least one projection For example, the modified atmosphere may comprise nitrogen and/or carbon dioxide.

Detailed Description

Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 depicts a perspective view of a base structure in accordance with the claimed invention; Figure 2 depicts a top view of the base structure of Figure 1; Figure 3 depicts a deconstructed view of the base structure of Figure 1; Figure 4A depicts a deconstructed side view of the base structure of Figure 1 with a film lid affixed to the base structure; Figure 4B depicts a magnified view of the flange of the base structure of Figure 4A; Figure 5A depicts a side view of a film lid affixed with a rounded seal to the flange of a second embodiment of the base structure of the first aspect of the invention; Figure 5B depicts a side view of a film lid affixed with a flat seal to the flange of a second embodiment of the base structure of the first aspect of the invention; and Figure 6 depicts a method in accordance with the third aspect of the present invention.

In the following description, it is understood that contaminants present on the flange particularly include goods and contents housed within the base volume which have been splashed, spilt or are otherwise loose and present on the flange, and are not limited to external contaminants. Contaminants present on the flange prior to affixing the lid film are common, in particular in the filling and packaging process, wherein movement of the base structure and vessels used to pour contents into the base structure and manual handling of the base structure may cause accidental spillage onto the flange.

It is also understood that a film lid may be any suitable lid structure and is not limited to a plastic film. The film lid may comprise a plurality of layers, but in particular may be a film lid less than 1mm in thickness, or more preferably less than 500 pm in thickness. It is envisaged that the film lid is unperforated such that an airtight seal can be formed over the base volume when a film lid is affixed to the base structure. In this way, a modified atmosphere can be introduced and maintained within the base structure.

With reference to Figures 1-4, there is illustrated a base structure 100 comprising a base volume 105 and a flange 110 defining an opening of the base volume 105. In this embodiment, the base volume 105 is substantially cuboid with a substantially rectangular cross section. However the shape of the base volume 105 is not particularly limited and may be, for example, cylindrical or another type of prism. In use, the base structure can be filled with goods or other contents, such as food stuffs, such that the contents of the base structure 100 occupy the base volume 105 but do not overflow the base volume 105.

The flange 110 extends from the base volume 105 about the perimeter 145 of the base volume 105, such that any overflowing contents from the base volume 105 overflow onto the flange 110. As shown in the figures, the flange 110 extends in substantially the same plane as the opening of the base volume 105 and is located centrally on the flange 110.

The flange 110 comprises three projections 115 with each projection 115 extending away from the base volume 105. The three projections 115 extend continuously around the perimeter 145 of the base volume 105. The three projections 115 comprise a central projection 115b, a first outer projection 115a located between the central projection 115b and the base volume 105, and a second outer projection 115c located between the central projection 115b and an outer perimeter 120 of the flange 110. The first outer projection 115a and the second outer projection 115c are angled towards one another.

The central projection 115b is separated from the first outer projection 115a by a first channel 150a, and the central projection 115b is separated from the second outer projection 115c by a second channel 150b. The first channel 150a and the second channel 150b are of substantially equal width and have an triangular cross section along their length. The cross section of each channel 150a, 150b is constant along their length. The movement of any contaminants trapped within the first channel 150a or second channel 150b is substantially unhindered about the perimeter 145 of the base volume 105.

The first outer projection 115a comprises a first face 155a and a second face 155b, the first face 155a located closer to the base volume 105 than the second face 155b, wherein the angle between the normal N to the flange 110 and the first face 155a is greater than the angle between the normal N to the flange 110 and the second face 155b. The second outer projection 115c comprises a first face 160a and a second face 160b, the first face 160a located closer to the outer perimeter 120 of the flange 110 than the second face 160b, wherein the angle between the normal N to the flange 110 and the first face 160a is greater than the angle between the normal N to the flange 110 and the second face 160b. As can be seen from Figures 4A and 4B, the second faces 155b, 160b of the outer projections 115a, 115c are steeper than their inner faces 155a, 160a. The cross section of the central projection 115b is symmetrical about the normal N to the flange 110 and is constant along the length of the central projection 115b.

All three projections 115a, 115b, 115c are of substantially the same height and each projection 115a, 115b, 115c tapers in height with distance from the base volume 105. In this embodiment, each projection 115a, 115b, 115c tapers to a point. As shown in Figures 1 and 3, the projections 115a, 115b, 115c are planar and this plane is parallel to the opening of the base volume 105. In this way, a film lid affixed to the projections 115a, 115b, 115c will also sit planar and parallel to the opening of the base volume 105.

In this embodiment, the base structure 100 is made entirely from PET (polyethylene terephthalate), although the type of material is not particularly limited.

The flange 110 further comprises a lipped surface 130 extending from the outer perimeter 120. The lipped surface 130 comprises a lip 135 extending continuously around the perimeter 145 of the base volume 105. The lipped surface 130 of the flange 110 is arranged to extend at an acute angle to a side wall 140 defining the base volume 105.

The base volume 105 further comprises a number of impressions 125. The type, size and number of impressions 125 is dependent on the application and contents of the base structure 100. In this embodiment, some of the impressions 125 extend into the base volume 105, reducing the total volume of the base volume 105, and some of the impressions 125 extend away from the base volume 105, increasing the total volume of the base volume 105. The function of the impressions 125 is to improve ease of handling the base structure, improve rigidity of the base structure 100 and/or reduce the risk of warping and bursting when a film lid 200 is affixed to the base structure 100.

A method 600 is shown in Figure 6, the method 600 including the steps of PROVIDE BASE STRUCTURE 601, wherein the base structure 100 is provided. There follows a PLACE PRODUCT 602 step, wherein at least one product is placed in the base volume 105 of the base structure 100. Finally, there follows a SEAL 603 step, comprising sealing the base volume 105 with a film lid 200 by affixing the film lid 200 to the projections 115a, 115b, 115c. In this way, a hermetic seal is formed over the base volume 105 such that the product held within the base volume 105 is held within an airtight atmosphere.

Figures 5A and 5B depict a second embodiment of the base structure 100 of Figures 14 and in the following description similar numerals will be used for similar parts of the second embodiment of the present invention. As shown in Figures 5A and 5B, a film lid 200 can be affixed to the base structure 500 in a number of configurations. In Figures 5A and 5B heat sealing is employed, wherein the film lid 200 and base structure 500 are subjected to high temperature and pressure along their points of contact such that they are affixed together.

In Figure 5A, a 'rounded' seal is illustrated. Namely, the film lid 200 is affixed to each tapered end of the outer projections 515a, 515c. The film lid 200 is further affixed to the first face 555a of the first outer projection 515a and to the first face 560a of the second outer projection 515c. In this embodiment, the film lid 200 does not contact the central projection 515b, although sealing of the film lid 200 against the central projection 515b is envisaged in some embodiments. In this way, the film lid 200 crosses the tapered ends of the projections and is pressed downward on the outermost faces 555a, 560a of the outer projections 515a, 515c. As such, the film lid 200 forms a rounded, dome like seal over the three projections 515a, 515b, 515c. Contaminants trapped within the first channel 550a and second channel 550b are free to move between channels 550a, 550b and about the perimeter of the base volume.

In Figure 5B, a flat' seal is illustrated. Herein, the film lid 200 is affixed to the tapered end of each of the three projections 515a, 515b, 515c only. The film lid 200 thus maintains a planar line across all ends of the projections 515a, 515b, 515c and consequently the base volume.

Burst Testing A base structure in accordance with the present invention was compared to a known 'flat flange' base structure. It is understood that a flat flange' base structure is well known in the art and is a base structure that has a substantially flat flange without any projections. The test conditions were kept constant across experiments, and in each case a base structure measuring 132 mm by 122 mm was used alongside a polyethylene terephthalate (PET) film lid with a 500 pm thickness. Examples 1-4 comprise the base structure of the present invention and Comparative Examples 1-4 comprise a known flat flange' base structure.

Each sample was partially filled with a volume water and no modified atmosphere was added. A PET film lid (KM Packaging PET-3G 25/ P21) was heat-sealed to each base structure to produce a 'flat' seal, as shown in Figure 5B, using a six spring, 2997N force seal at 160°C for 0.5 seconds such that a hermetic seal was formed. Each sample was then tested using a vacuum pressure tank. The vacuum in the vacuum pressure tank was increased slowly to -30 kPa and held at -30 kPa for 30 seconds. If the sealed sample withstood the 30 seconds at -30 kPa then the vacuum pressure was increased slowly to the point at which the sample fails.

Each sealed sample was tested for either burst or leak. A burst failure is shown by a mass of air appearing in the water and the pack deflating quickly. A leak failure is shown by a constant stream of bubbles from one or more areas of the base structure. Further, a sealed sample can fail in two ways; as a seal failure or as a film failure. A seal failure is shown by the film lid lifting from the base structure in the area it was sealed in and a film failure is shown by a break or fracture inside the seal line. In the case of a film failure, the seal made between the film lid and the base structure remains intact.

The samples were tested with both an uncontaminated seal, namely no contaminants present on the flange of the base structure, and a seal contaminated with chicken fats.

While the burst test result is representative of the geometry of the tray and volume of air in the pack, standard measurements seen through testing are shown in Table 1.

Table 1

Force (kPa) Pass Rate > -20 Fail -25 Low

-30 Acceptable

-35 Substantial -40 Good -45 Firm <-50 Obvious Pass The test results for a non-contaminated flange seal are shown in Table 2. The type of failure observed with each sample was also noted.

Table 2

Base Sample Failure Force (kPa) Pass Rate % Improvement over Comparative Example Failure Type Structure Material Recycled Polyethylene Terephthalate Example 1 -75 Obvious Pass 0 No Failure Comparative Example 1 -75 Obvious Pass No Failure Recycled Polyethylene Terephthalate Example 2 -35 Substantial -19 Leaked/ Burst Comparative -43 Good Burst

Anti-Block Example 2

Commercially Available Polyethylene Product (TDX Seal PET) Example 3 -35 Substantial -22 Burst Comparative Example 3 -45 Firm Burst Recycled Polyethylene Terephthalate with Resin Example 4 -36 Substantial -17 Burst Comparative Example 4 -43 Good Burst The results of the uncontaminated flange seal tests show that Examples 1-4 performed above an acceptable level on burst testing, with failure occurring above -30 kPa. In particular, Example 1 performed well, meeting an obvious pass standard. As such, the present invention performs more than adequately when no contaminants are present on the flange of the base structure.

The test results for a contaminated flange seal (using chicken fat as the contaminant) are shown in Table 3.

Table 3

Base Sample Failure Force (kPa) Pass Rate % Improvement over Comparative Example Failure Type Structure Material Recycled Polyethylene Terephthalate Example 1 -61 Obvious Pass +21 Leaked/ Burst Comparative Example 1 -51 Obvious Pass Leaked/ Burst Recycled Polyethylene Terephthalate Example 2 -30 Acceptable +7 Leaked/ Burst Comparative -28 Low Burst

Anti-Block Example 2

Commercially Available Polyethylene Product (TDX Seal PET) Example 3 -34 Acceptable +18 Leaked/ Burst Comparative Example 3 -29 Low Leaked/ Burst Recycled Polyethylene Terephthalate with Resin Example 4 -34 Acceptable +10 Leaked/ Burst Comparative Example 4 -31 Acceptable Leaked/ Burst The results of the contaminated flange seal tests show that Examples 1-4 achieved higher pressure before sample failure occurred than each corresponding Comparative Example. As such, the seal provided by the base structure of the claimed invention is superior in preventing both burst and leak failure when contaminants are present on the flange of the base structure. As such, the present invention provides a superior seal as shown with improved results in burst tests.

Further embodiments within the scope of the present invention may be envisaged that have not been described above, for example, there may be different shapes of the base structure and base volume. Additionally, the base structure may be made of a recycled polyethylene terephthalate (rPET) and resin composition, providing improved adhesion characteristics between the film lid and the base structure. Polyethylene (PE) films typically provide a better adhesion on contaminated surfaces, however adhesion of PE with polyethylene terephthalate (PET) may reduce or spoil the recyclability of the packaging materials. The present invention provides an improved solution for recyclability of mono-polyethylene terephthalate (mono-PET) base structures by allowing use with a like PET film lid, while also reducing waste by reducing sealing malfunctions. The invention is not limited to the specific examples or structures illustrated, a greater number of components than are illustrated in the figures could be used, for example.

Claims

Claims 1 A base structure for a container, said base structure comprising a base volume; and a flange defining an opening of the base volume, said flange extending from the base volume about the perimeter of the base volume; said flange comprising at least one projection, wherein said at least one projection extends away from said base volume, and further wherein said at least one projection extends around a majority of said perimeter of said base volume.
2. The base structure of claim 1, wherein said at least one projection extends around at least 90% of said perimeter of said base volume.
3. The base structure of claim 2, wherein said at least one projection extends continuously around said perimeter of said base volume.
4. The base structure of any one preceding claim, wherein said flange comprises at least two projections separated by a channel.
The base structure of claim 4, wherein said flange comprises a central projection, a first outer projection located between said central projection and said base volume, and a second outer projection located between said central projection and an outer perimeter of said flange.
6. The base structure of claim 5, wherein said central projection is separated from said first outer projection by a first channel, and further wherein said central projection is separated from said second outer projection by a second channel.
7. The base structure of claim 6, wherein said first channel and said second channel are of substantially equal width.
8. The base structure of any one of claims 5 to 7, wherein said first outer projection and said second outer projection are angled towards one another.
9 The base structure of any one of claims 5 to 8, wherein the first outer projection comprises a first face and a second face, the first face located closer to the base volume than the second face, wherein the angle between the normal to the flange and the first face is greater than the angle between the normal to the flange and the second face.
10. The base structure of any one of claims 5 to 8, wherein the second outer projection comprises a first face and a second face, the first face located closer to the outer perimeter of the flange than the second face, wherein the angle between the normal to the flange and the first face is greater than the angle between the normal to the flange and the second face.
11. The base structure of any one of claims 4 to 10, wherein said two or more projections are of substantially the same height.
12. The base structure of any one preceding claim, wherein said at least one projection tapers in height.
13. The base structure of any one preceding claim, wherein said flange extends in substantially the same plane as the opening of said base volume.
14. The base structure of any one preceding claim, wherein said flange is arranged to extend at an acute angle to a wall defining the base volume The base structure of any one preceding claim, wherein said at least one projection is located centrally on said flange.16.A kit of parts comprising a film lid and the base structure of any one preceding claim.17.A method, the method comprising providing the base structure of any one of claims 1 to 15; placing at least one product in the base volume of said base structure; and sealing said base volume with a film lid by affixing said film lid to said at least one projection.18 The method of claim 17, wherein the method further comprises the step of introducing a modified atmosphere into said base volume prior to sealing said base volume with said film lid.