Tray, packaging, and method for forming packaging

Abstract

The present invention relates to a tray comprising a base, a continuous side wall extending from the base, a peripheral flange extending along the upper, in use, edge of the continuous side wall, and a rib pattern, wherein the rib pattern comprises at least one spine and a plurality of stiffening ribs radially extending from the spine and wherein the width of the stiffening ribs is no more than 50 % of the width of the spine and / or wherein the height of the stiffening ribs is no more than 30% of the height of the spine. The present invention relates to a packaging comprising the tray, to methods for producing the tray and the packaging and for sealing the tray.

Description

LINPAC Packaging Limited 1 274 477 r48 / ktoTRAY, PACKAGING, ANDMETHOD FOR FORMING PACKAGINGTECHNICAL FIELD

[0001] The present invention relates to trays suitable for use in the packaging, storage, transportation and / or display of a product, such as a fresh food product or a medical product, to packaging comprising said tray, and to methods for manufacturing such trays and packaging.BACKGROUND

[0002] It is known to use plastic containers to package, store, transport and display fresh food. These containers (or packaging) typically comprise a plastic tray which may be sealed with a lidding film to protect the product within the container from the surrounding environment. Additionally, the atmosphere within the containers may be controlled or modified (so-called Controlled Atmosphere Packaging “CAP” or Modified Atmosphere Packaging “MAP”) to enhance the shelf-life and / or appearance of the fresh product within the container.

[0003] The trays must be sufficiently strong to contain one or more products without cracking, bending, or deforming in any other way, to create a high quality packaging appearance. The trays must be sufficiently robust to sustain handling, during the processes of manufacturing, filling, sealing, storing in an empty or filled state, transporting and / or displaying. Indeed, any damage to the tray can potentially compromise the integrity of the seal or of the tray itself, or result in a leak of the modified atmosphere, which in turn would decrease the shelf-life of the fresh product and affect the appearance of the packaged product.

[0004] A straightforward solution to improve the structural integrity of a tray is to increase the thickness of the tray. A thicker tray is a stronger tray. However, the production of such trays requires a greater amount of plastic material. If the trays are formed by injectionmolding, more melted plastic material must be injected into the mold; if the trays areproduced through a thermoforming process, the sheets from which the trays are formed must be thicker. This solution therefore involves more material, greater material, production and transportation costs, more production waste and post-consumer waste and, if the waste material is not recyclable and not recycled, is detrimental to the environmental.

[0005] Another way to improve the structural integrity of the tray is to provide the tray with strengthening ribs. Typically, the portion of the tray to be strengthened (for example, the base, the side walls and / or, if present, the flange) is provided with plurality of ribs configured in a pattern. The ribs are substantially parallel to each other or substantially concentric to strengthen the area of the tray in which they are located.

[0006] In order to strengthen the tray both in the longitudinal and lateral directions, the tray may be provided with longitudinal and lateral ribs, with the longitudinal ribs crossing over or intersecting the lateral ribs. The inventors have observed that the intersection of the ribs constitutes a point of structural weakness in the tray.

[0007] The trays may have a weak and somewhat floppy appearance and feel, especially at the rib intersections, thereby resulting in poor customer experience. The trays may even split or cracks at the junction between two ribs where it is the most vulnerable to damage. Conditions such as impact, high pressure, and / or low temperature exacerbate this issue. For example, a tray may become damaged during handling and transport. The tray may become damaged when stacked in a pile with under the weight of the trays stacked above it, especially (but not only) when the containers are filled with a product. Furthermore, some plastic material, such as PET, become brittle at low temperatures. There is therefore an increased risk of damage when trays, in particular sealed packaging, are subjected to impact at low temperatures.

[0008] Most sealing processes to apply a lidding film onto a filled tray involve the use of heat and / or pressure either to melt and fuse (a layer or a thickness of) the lidding film with (a layer or a thickness of) the tray together in a so-called “heat-seal” process. The heat and / or pressure can compromise the integrity of the tray material, which may weaken, deform, orwarp. This effect is particularly pronounced in thin trays; the low gauge making it difficult to seal the trays without deformation or warping.

[0009] It is an object of this invention to mitigate problems such as those described above and to provide an improved alternative to existing products. In particular, there is a need for a tray that is economically produced, with minimal impact on the environment, and with enhanced structural integrity.SUMMARY OF THE INVENTION

[0010] According to an aspect of the invention, there is provided a tray comprising a base, a continuous side wall extending from the base, a peripheral flange extending along the upper, in use, edge of the continuous side wall, and a rib pattern formed in the base and / or continuous side wall, wherein the rib pattern comprises at least one spine and a plurality of stiffening ribs radially extending from the spine and wherein the width of the stiffening ribs is no more than 50% of the width of the spine and / or wherein the height of the stiffening ribs is no more than 30% of the height of the spine.

[0011] The width of the stiffening ribs may be no more than 40%, no more than 30%, no more than 20%, no more than 19%, no more than 18%, no more than 17%, or no more than 15% of the width of the spine.

[0012] According to embodiments, the width of the spine is from 2.0 mm to 3.0 mm.

[0013] According to embodiments, the width of the stiffening ribs is from 0.3 mm to 1.0 mm.

[0014] The width of the stiffening ribs may be at least 0.3 mm, preferably at least 0.4 mm, and most preferably at least 0.5 mm, in particular when the tray is manufactured by thermoforming. The width of the stiffening ribs may be no more than 1mm, preferably no more than 0.9 mm, most preferably no more than 0.8 mm.

[0015] According to embodiments, the height of the stiffening ribs is no more than 30% of the height of the spine. The height of the stiffening ribs may be no more than 25%, no more than 20%, or no more than 15% of the height of the spine.

[0016] According to embodiments, the height of the spine is from 1.3 mm to 3.0 mm.

[0017] According to embodiments, the height of the stiffening ribs is from 0.3 mm to 1.0 mm.

[0018] The height of the stiffening ribs may be at least 0.3mm, preferably at least 0.4 mm, most preferably at least 0.5mm. The height of the stiffening ribs may be no more than 1.0 mm, preferably no more than 0.9 mm, most preferably no more than 0.8 mm.

[0019] According to embodiments, the rib pattern comprises at least two strengthening ribs, at least one spine positioned longitudinally between the two strengthening ribs, and a plurality of stiffening ribs radially extending from the spine to one of the strengthening ribs.

[0020] According to embodiments, the strengthening ribs extend from a first side wall to a second side wall adjacent the first side wall.

[0021] According to embodiments, the distance between two adjacent stiffening ribs is between 5 mm and 15 mm, more preferably, 7 to 10 mm, most preferably around 8 mm.

[0022] According to embodiments, the width of the strengthening ribs is greater than the width of the spine.

[0023] According to embodiments, one or more stiffening ribs may contact one or more spines. In embodiments, the contact angle between a spine and a stiffening rib between 25° and 90°, preferably between 45° and 75°, most preferably around 60°.

[0024] According to embodiments, one or more strengthening ribs may contact one or more spines. In embodiments, the contact angle between a spine and a strengthening rib between 30° and 55°, preferably between 40° and 50°, most preferably around 45°.

[0025] According to embodiments, the width of the spine is no more than 80% of the width of the strengthening ribs. The width of the spine may be no more than 70 %, no more than 60 %, or no more than 50 % of the width of the strengthening ribs.

[0026] According to embodiments, the width of the strengthening ribs is from 4.5 mm to 7mm.

[0027] According to embodiments, the height of the strengthening ribs is from 3 mm to 5 mm.

[0028] According to embodiments, the stiffening ribs are substantially parallel to each other.

[0029] According to embodiments, the spine comprises one or more substantially linear sections, one or more curved sections and / or one or more undulated sections.

[0030] According to embodiments, one or more stiffening ribs comprises one or more substantially linear sections, one or more curved sections and / or one or more undulated sections.

[0031] According to embodiments, the base of the tray comprises four quadrants, and each quadrant comprises at least one rib pattern.

[0032] According to embodiments, the tray comprises or consists of polyethylene terephthalate, optionally of amorphous polyethylene terephthalate. According to embodiments, the tray comprises or consists of polypropylene.

[0033] According to embodiments, the tray comprises a layer of adhesive on the upper, in use, surface of the peripheral flange.

[0034] According to embodiments, the thickness of the layer of adhesive is from 20pm to 100pm.

[0035] According to embodiments, the tray comprises at least one denesting recess formed in a denesting area, where the denesting area is relieved relative to the upper, in use, surface of the peripheral flange.

[0036] According to embodiments, the denesting recess and denesting area are free of adhesive.

[0037] According to another aspect of the invention, there is provided a tray comprising a base, a continuous side wall extending from the base, a peripheral flange extending along the upper, in use, edge of the continuous side wall, and a rib pattern formed in the base and / or continuous side wall, wherein the rib pattern comprises at least two strengthening ribs, a spine extending longitudinally between the two strengthening ribs and a plurality of stiffening ribs radially extending from the spine to one of the strengthening ribs.

[0038] According to embodiments, the strengthening ribs extend from a first side wall to a second side wall adjacent the first side wall.

[0039] According to embodiments, the width of each strengthening rib is greater than the width of the spine.

[0040] According to embodiments, the width of the spine is no more than 80% of the width of the strengthening ribs. The width of the spine may be no more than 70 %, no more than 60 %, or no more than 50 % of the width of the strengthening ribs.

[0041] According to embodiments, the width of the strengthening ribs is from 4.5 mm to 7mm.

[0042] According to embodiments, the height of the strengthening ribs is from 3 mm to 5 mm.

[0043] According to embodiments, the width of the spine is greater than the width of the stiffening ribs.

[0044] According to embodiments, the width of the stiffening ribs is no more than 50% of the width of the spine.

[0045] The width of the stiffening ribs may be no more than 40%, no more than 30%, no more than 20%, no more than 19%, no more than 18%, no more than 17%, or no more than 15% of the width of the spine.

[0046] According to embodiments, the width of the spine is from 2.0 mm to 3.0 mm.

[0047] According to embodiments, the width of the stiffening ribs is from 0.3 mm to 1.0 mm.

[0048] The width of the stiffening ribs may be at least 0.3 mm, preferably at least 0.4 mm, and most preferably at least 0.5 mm. The width of the stiffening ribs is no more than 1mm, preferably no more than 0.9 mm, most preferably no more than 0.8 mm.

[0049] According to embodiments, the height of the stiffening ribs is no more than 30% of the height of the spine. The height of the stiffening ribs may be no more than 25%, no more than 20%, or no more than 15% of the height of the spine.

[0050] According to embodiments, the height of the spine is from 1.3 mm to 3.0 mm.

[0051] According to embodiments, the height of the stiffening ribs is from 0.3 mm to 1.0 mm.

[0052] The height of the stiffening ribs may be at least 0.3mm, preferably at least 0.4 mm, most preferably at least 0.5mm. The height of the stiffening ribs is no more than 1.0 mm, preferably no more than 0.9 mm, most preferably no more than 0.8 mm.

[0053] According to embodiments, two or more the stiffening ribs are substantially parallel to each other.

[0054] According to embodiments, the spine comprises one or more substantially linear sections, one or more curved sections and / or one or more undulated sections.

[0055] According to embodiments, one or more stiffening ribs comprises one or more substantially linear sections, one or more curved sections and / or one or more undulated sections.

[0056] According to embodiments, the base of the tray comprises four quadrants, and each quadrant comprises at least one rib pattern.

[0057] According to embodiments, the tray comprises or consists of polyethylene terephthalate, optionally of amorphous polyethylene terephthalate. According to embodiments, the tray comprises or consists of polypropylene.

[0058] According to embodiments, the tray comprises a layer of adhesive on the upper, in use, surface of the peripheral flange.

[0059] According to embodiments, the thickness of the layer of adhesive is from 20pm to 100pm.

[0060] According to embodiments, the tray comprises at least one denesting recess formed in a denesting area, where the denesting area is relieved relative to the upper, in use, surface of the peripheral flange.

[0061] According to embodiments, the denesting recess and denesting area are free of adhesive.

[0062] According to another aspect of the invention, there is provided a packaging comprising a tray according to the present disclosure and a lidding film which may be sealedto the peripheral flange to create a sealed space between the base, side walls and lidding film.

[0063] According to embodiments, the lidding film is a multilayer film comprising at least a seal layer.

[0064] According to embodiments, the seal layer comprises or consists of polyethylene and / or polypropylene.

[0065] According to embodiments, the lidding film is sealed onto the peripheral flange and wherein the atmosphere within the sealed packaging is modified or controlled.

[0066] According to another aspect of the invention, there is provided a method for manufacturing a tray according to the present disclosure, comprising the step of thermoforming one or more trays from a sheet of plastic material.

[0067] According to embodiments, the sheet of plastic material is a multi-layer sheet.

[0068] According to embodiments, the plastic material comprises or consists of polyethylene terephthalate, optionally of amorphous polyethylene terephthalate.

[0069] According to embodiments, the method for manufacturing a tray comprises the step of applying a layer of adhesive on the upper, in use, surface of the peripheral flange.

[0070] According to embodiments, the peripheral flange is supported during the application of the layer of adhesive.

[0071] According to embodiments, the method is a continuous process.

[0072] According to another aspect of the present invention, there is provided a method for forming a packaging according to the present disclosure, providing a tray according to the present disclosure; and providing a lidding film.

[0073] According to embodiments, the method for forming a packaging comprises the step of manufacturing the tray according to the present disclosure.

[0074] According to embodiments, the method for forming a packaging comprises the step of sealing the lidding film onto the peripheral flange of the tray.

[0075] According to embodiments, the step of sealing the lidding film onto the peripheral flange of the tray includes the application of heat and / or pressure.

[0076] According to embodiments, the heat and / or pressure is applied for a period of 0.5 second to 1 second.

[0077] According to embodiments, the sealing temperature is from 110°C to 150°C, preferably 130°C.

[0078] According to embodiments, the peripheral flange is supported during the step of sealing the lidding film onto the peripheral flange of the tray.

[0079] According to embodiments, the container is laser treated, corona treated or plasma treated, prior to the step of sealing the lidding film onto the peripheral flange of the tray.

[0080] According to embodiments, the method for forming a packaging comprises the step of modifying or controlling the atmosphere within the sealed container.BRIEF DESCRIPTION OF THE DRAWINGS

[0081] The details of one or more implementations are set forth, by way of example only, in the accompanying drawings and the description below. Other features, aspects, and advantages of the disclosure will become apparent from the description, the drawings, and the claims, in which:

[0082] Figure l is a schematic representation of a first exemplary tray with a first rib pattern;

[0083] Figure 2 is a schematic representation of a second exemplary tray with a second rib pattern;

[0084] Figure 3 is a schematic representation (top perspective view) of a first tray according to the present invention;

[0085] Figure 4 is a schematic representation (bottom perspective view) of the tray of Figure 3;

[0086] Figures 5A and 5B are schematic representations (top and bottom view, respectively) of the tray of Figure 3;

[0087] Figures 6A to 6D are schematic representations (right-side, left-side, front and rear view, respectively) of the tray of Figure 3;

[0088] Figures 7A and 7B are schematic representations (top perspective and bottom perspective view, respectively) of a second tray according to the present invention;

[0089] Figures 8A to 8E are schematic representations (top perspective, bottom perspective, top, front, and left-side view, respectively) of a third tray according to the present invention;

[0090] Figure 9 is a schematic cross sectional representation of a rib or a spine; and

[0091] Figure 10 is cross sectional representations of exemplary strengthening rib, spine and stiffening rib.DETAILED DESCRIPTION

[0092] The embodiments described herein are provided as exemplary and non-limiting embodiments of the present invention.

[0093] Within the context of the present disclosure directional terms such as up, down, right, left, front, back, top, bottom, above, below, are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0094] Within the context of the present disclosure, the expression “longitudinal walls” designates the two longer walls in a substantially rectangular tray, and the expression “lateral wall” designates the two shorter walls. However, it will be understood that these expressions are used merely to differentiate sets of opposing walls and are not limiting to any specific lengths.

[0095] Within the context of the present disclosure, the numerical ranges may include the end point values.

[0096] With reference to Figure 1, there is illustrated a first exemplary tray comprising a base, two longitudinal side walls, two lateral side walls and a flange extending along the upper edge of the side walls. The tray comprises a first set of lateral strengthening ribs extending from the flange along a first longitudinal wall, across the base, and to the flange along the opposite longitudinal wall. The tray also comprises two sets of longitudinal strengthening ribs extending from the flange along a lateral wall to the closest and outermost lateral strengthening rib. The junction between a lateral strengthening rib and a longitudinal strengthening rib constitutes a point of structural weakness. In addition, it was observed that the section of tray comprising only lateral ribs was susceptible to structural weakness and / or damage in the areas between the lateral ribs and devoid of any strengthening features.

[0097] With reference to Figure 2, there is illustrated a second exemplary tray also comprising a base, two longitudinal side walls, two lateral side walls and a flange extending along the upper edge of the side walls. The tray comprises parallel strengthening ribs extending from the flange and across the side walls. The strengthening ribs from the longitudinal walls extend across the width of the base to form 1. The strengthening ribs from the lateral walls intersect with the lateral strengthening ribs, thereby forming points of structural weakness.

[0098] Without wishing to be bound by theory, the rib patterns illustrated in Figures 1 and 2 are formed by ribs of significant absolute widths and of substantially similar relative widths, so that joining ribs form intersecting areas which, in the absence of strengthening features, are structurally weak voids.

[0099] With reference to Figure 3, there is illustrated a first tray according to the present invention.

[0100] The tray 1 comprising a base 2, a continuous side wall 3 extending from the base, a peripheral flange 4 extending along the upper, in use, edge of the continuous side wall 3, and a rib pattern, wherein the rib pattern comprises at least one spine 5 and a plurality of stiffening ribs 6 radially extending from the spine 5 and wherein the width of the stiffening ribs 6 is no more than 50% of the width of the spine 5.

[0101] Within the context of the present disclosure, the width of a stiffening rib, of a spine, or of a reinforcing rib is measured across the plane of surface in which the rib or spine is formed (e.g., from a longitudinal edge to the opposite longitudinal edge), as illustrated in Figures 9A to 9C.

[0102] In this embodiment, the tray 1 comprises a first set of opposing side walls 3a (or lateral side walls) and a second set of opposing side walls 3b (or longitudinal side walls). The peripheral flange 4 extends along the upper edge of the side walls 3, and comprises a substantially flat upper surface upon which a lidding film (not shown) may be applied.

[0103] The tray 1 may comprise a number of features to reinforce the structural integrity of the tray 1. Such reinforcing features include rib patterns including spines 5 and stiffening ribs 6, strengthening ribs 7, protrusions 8 (or recesses) extending partially across the side walls 3.

[0104] According to the present invention, the tray 1 comprises a rib pattern comprising a spine 5 and a plurality of ribs 6 extending radially therefrom. Any surface of the tray 1 may comprise one or more rib patterns. The tray 1 may be divided into four quadrants, each quadrant comprising a single or several rib patterns.

[0105] The rib pattern according to the present invention comprises a plurality of stiffening ribs (or “stiffeners”) which extend from a spine. The absolute and relative dimensions of the stiffeners are notably smaller than that of ribs conventionally used in plastic trays.

[0106] According to the present invention, the width of the stiffening ribs 6 is no more than 40% of the width of the spine 5 it extends from. The width of the stiffening ribs may be no more than 40%, no more than 30%, no more than 20%, no more than 19%, no more than 18%, no more than 17%, or no more than 15% of the width of the spine.

[0107] The relative width and / or of the stiffening ribs 6 relative to the spine 5 (and / or to the strengthening ribs 7) are such that the ribs do not “cross-over” the spines to create a large cross-shaped intersection devoid of strengthening features, a void. The dimensions of the stiffening ribs 6 are such that there is no substantial increase of the width of the spine at the junction point, and therefore minimal increase of the (structurally unprotected) intersection area.

[0108] In embodiments, the absolute width of the stiffening ribs 6 is no more than 1 mm, preferably no more than 0.9 mm, most preferably no more than 0.8 mm. As noted above, the small dimensions of the stiffening ribs and configuration of the rib pattern allow the strengthening of the tray, without the creation of structurally weaker voids. Furthermore, the dimensions of the stiffening ribs 6 allows to increase the number of stiffening ribs 6 within a specific area, i.e., to increase the stiffening rib density and thereby further improving the structural integrity of the area in which they are formed. In addition, the small dimensions of the stiffening ribs allows to maximise the amount of space available for the product to be contained in the packaging.

[0109] In embodiments, the width of the stiffening ribs is at least 0.3 mm, preferably at least 0.4 mm, and most preferably at least 0.5 mm, in particular when the tray is manufactured by thermoforming. Trays, with structurally sound ribs with these dimensions can be formed through a thermoforming process.

[0110] The stiffening ribs 6 in a rib pattern may have the same or different relative widths. The stiffening ribs 6 in a rib pattern may have the same or different absolute widths.

[0111] In embodiments, the height of the stiffening ribs is no more than 30% of the height of the spine it extends from, the height of the stiffening ribs is no more than 30% of the height of the spine. The height of the stiffening ribs may be no more than 25%, no more than 20%, or no more than 15% of the height of the spine. The height of the spine is from 1.3 mm to 3.0 mm. The height of the stiffening ribs is from 0.3 mm to 1.0 mm. In embodiments, the height of the stiffening ribs may be at least 0.3mm, preferably at least 0.4 mm, most preferably at least 0.5mm. The height of the stiffening ribs may be no more than 1.0 mm, preferably no more than 0.9 mm, most preferably no more than 0.8 mm.

[0112] The stiffening ribs 6 in a rib pattern may have the same or different relative heights. The stiffening ribs 6 in a rib pattern may have the same or different absolute heights.

[0113] Within the context of the present disclosure, the height of a rib or spine is measured between the plane of the base of the rib or spine to the uppermost point of the rib or spine, as illustrated in Figures 9 A to 9C.

[0114] The cross-section of the strengthening ribs and / or of a spine may be substantially parabolic, substantially semi-circular, or shaped as a partial rounded square or rectangle, as illustrated in Figures 9A to 9C. Most preferably, the section of the strengthening ribs may be substantially parabolic for enhanced structural integrity. The spines 6 in a tray 1, may have the same or different cross-sectional shapes. The strengthening ribs 7 in a tray 1, may have the same or different cross-sectional shapes.

[0115] The stiffening ribs 6 within a rib pattern may or may not be parallel to each other. For example, all stiffening ribs 6 or a sub-group of stiffening ribs 6 may be parallel to each other. In embodiments, a rib pattern may comprise a first sub-group of parallel stiffening ribs 6 and a second sub-group of parallel stiffening ribs 6, wherein the first sub-group is not parallel to the second sub-group.

[0116] In embodiments, the spine 5 comprises one or more substantially linear sections, one or more curved sections and / or one or more undulated sections. The spine 5 may extend solely on one surface, such as the base 2, or on several surfaces, such as the base 2 and one or more side walls 3.

[0117] In embodiments, the strengthening rib 7 comprises one or more substantially linear sections, one or more curved sections and / or one or more undulated sections. The strengthening rib 7 may extend solely on one surface, such as the base 2, or on several surfaces, such as the base 2 and one or more side walls 3.

[0118] In embodiments, one or more stiffening ribs 6 comprises one or more substantially linear sections, one or more curved sections and / or one or more undulated sections. In a preferred embodiment, the stiffening rib 6 consist of a substantially linear rib.

[0119] The stiffening ribs 6 may radially extend from one side of a spine 5, or from both sides of the spine 5. The stiffening ribs 6 may radially extend between two spines 5. A strengthening rib 7 may act as a spine, and the stiffening ribs 6 may radially extend from one side of a strengthening rib 7, or from both sides of the strengthening rib 7. The stiffening ribs 6 may radially extend between strengthening ribs 7, or between a strengthening rib 7 and a spines.

[0120] The rib pattern may comprise a first set of stiffening ribs 6a radially extending from one side of the spine 5, and a second set of stiffening ribs 6b radially extending from the other side of the spine 5. Stiffening ribs 6a of the first set may or may not be parallel to stiffening ribs 6b of the second set. Stiffening ribs 6a of the first set may or may not be aligned with stiffening ribs 6b of the second set, i.e., longitudinally extending from stiffening ribs 6b of the second set. The configuration (e.g., relative dimensions, absolute dimensions, shape, and / or angle) of one sub-group or set of stiffening ribs 6 may be the same or different from the configuration of a second sub-group or set of stiffening ribs 6.

[0121] The tray 1 may be notionally divided into four quadrants. Each quadrant may comprise one or more rib patterns according to the present disclosure. Any surface of thetray 1 may comprise a rib pattern, but preferably rib patterns are formed in the base and / or side walls which are most exposed to impact and / or pressure.

[0122] With reference to Figures 3 to 6, the tray 1 comprises a spine 5, a first set of stiffening ribs 6a extending from one side of the spine 5, and a second set of stiffening ribs 6b extending from one side of the spine 5. In this embodiment, the stiffening ribs 6a in the first set are substantially parallel to each other, and the stiffening ribs 6b in the second set are substantially parallel to each other. Some stiffening ribs 6a in the first set are substantially aligned with stiffening ribs 6b in the second set across the spine 5. Some stiffening ribs 6a in the first set are not aligned with stiffening ribs 6b in the second set.

[0123] The tray 1 comprises a plurality of strengthening ribs 7. In a preferred embodiment of the rib pattern, a spine 5 extends longitudinally between two strengthening ribs 7a, 7b, thereby forming a rib pattern comprising an inner spine 5 and two outer strengthening ribs 7a, 7b. Stiffening ribs 6, 6b extends radially from the spine 5 to the adjacent strengthening rib 7a, 7b. In other embodiments of the rib pattern, a spine 5 extends longitudinally adjacent a strengthening rib 7a and stiffening ribs 6, 6b extends radially from the spine 5 to the adjacent strengthening rib 7a. In other embodiments of the rib pattern, stiffening ribs 6, 6b extends radially between two adjacent strengthening ribs 7, for example. Within the context of the present disclosure, two “adjacent” strengthening ribs and / or spines are separated by an area devoid of strengthening ribs and / or spines.

[0124] The spine 5 may extend longitudinally adjacent a strengthening rib 7a or longitudinally between two strengthening ribs 7. The spine 5 may or may not contact the strengthening rib(s) 7.

[0125] The tray 1 may comprise one or more strengthening ribs 7 extending from one side wall to an opposite or adjacent side wall.

[0126] In figures 3 to 6, the tray 1 comprises a reinforcing rib 7a extending from one side wall 3a (for example a lateral wall) to an adjacent side wall 3b (for example a longitudinal wall). The reinforcing rib 7a comprises a substantially linear section across a surface of the base 5 and curved end sections, extending along the side walls 3a, 3b. The tray comprisesanother reinforcing rib 7b strengthening a corner of the tray 1. The reinforcing rib 7b extends from the side wall 3a to adjacent side wall 3b, and comprises a substantially linear section across a surface of the base 5 and curved end sections, extending along the side walls 3a, 3b. Reinforcing rib 7a and reinforcing rib 7b may be substantially parallel, concentric, and / or have a substantially similar configuration. The tray 1 may also comprise another strengthening rib 7c extending along the corner edge of the tray 1 and intersecting reinforcing rib 7b.

[0127] In embodiments, the width and / or height of the strengthening rib 7 is greater than the width and / or height of the spine 5. Thus, a rib pattern is achieved in which the dimensions of the strengthening rib 7 is greater than the dimensions of the spine 5, and the dimensions of the spine is greater than the dimensions of the stiffening ribs 6.

[0128] The tray 1 may further comprise strengthening protrusions or short ribs 8 extending along a section of the side walls 3, preferably extending from the upper edge of the side wall 3 to an intermediate point of the side wall 3 (and not extending to the base 2). In a preferred embodiment, the tray 1 comprises a plurality of strengthening protrusions 8 extending partially or completely along a side wall. Preferably, a protrusion 8 is positioned between two strengthening ribs 7 to strengthen the voids between said strengthening ribs. Preferably, the dimensions of the central protrusion 8 is greater than that of the adjacent protrusions, and the dimensions of the protrusions decrease from the centre to the end of the side wall 3. In embodiments, the protrusions 8 may be replaced with recesses.

[0129] Although the tray 1 illustrated in Figures 3 to 6 is substantially rectangular, the rib pattern according to the present disclosure, and the strengthening features described herein, may be applied to different tray shapes (square, rectangular trays, round, oval and the like).

[0130] Figures 7A and 7B illustrate a second tray according to the present invention, with dimensions greater than that of the first tray 1 illustrated in Figures 3 to 6. In such cases, the number of rib patterns may be increased to strengthen the increased surface area. For example, this second tray comprises in one quadrant three strengthening ribs. The area between the first and second strengthening rib and the area between the second and third rib are each strengthened by means of a spine and stiffening ribs.

[0131] The tray 100 illustrated in Figures 8A to 8E is intended for use in a packaging for (two) burgers. The tray 1 comprises a base 2, a continuous side wall 3 extending from the base, a peripheral flange 4 extending along the upper, in use, edge of the continuous side wall 3, and a rib pattern according to the present invention. Any features of tray 1 may be used in the tray 100 (and vice-versa) and the description of the features will not be repeated for the sake of conciseness.

[0132] The tray 100 comprises two substantially two semi-circular walls 103a and two longitudinal walls 103b. Longitudinal strengthening ribs 107 extend across the base 2 and between the two semi-circular walls 103a. Strengthening ribs 107b extend from a semicircular walls 103a to an adjacent longitudinal wall 103b. Substantially concentric strengthening ribs 107c also extend from a semi-circular walls 103a to an adjacent longitudinal wall 103b. In this embodiment, the strengthening ribs 107a, 107b, and 107c, each act as a spine for the stiffening ribs 106 extending therebetween. The tray 100 may comprise strengthening recesses 108 (or protrusions) extending partially or completely along the side walls, for example from the upper edge of the side wall.

[0133] The tray 1, 100 may be produced through a thermoforming process or an injection moulding process. Thermoforming processes are preferred in that they allow for high- throughput manufacture, for easy integration into in-line processes, and for continuous processes. Thermoforming processes are also preferred for the production of multilayer layer trays.

[0134] A thermoforming process may include the steps of melting pellets (virgin material) and / or flakes (usually, recycled material) into a sheet - some extrusion waste may be generated, rolling the sheet, feeding the sheet into a thermoforming machine, thermoforming the sheet into a plurality of trays, separating the trays from each other by cutting through the interconnecting web (thereby generating web waste), trimming the trays (thereby generating trimming waste).

[0135] The tray according to the present invention is preferably a plastic tray. The preferred material is polyethylene terephthalate (PET) and more preferably amorphous polyethyleneterephthalate (APET). The use of APET provides a high clarity tray that enables a user to view readily the contents of the packaging. When the tray consists of APET (so-called “mono-APET” trays), production waste and post-consumer waste can readily be recycled into new products, more particularly clear products. Thus, the tray according to the present disclosure may comprise or consist of amorphous PET. The tray may comprise or consist of recyclable plastic material, such as APET, or may comprise or consist of recycled plastic material, such as recycled APET. By contrast, multilayer trays, such as PETZEVA / PE multilayer trays, are less environmentally-friendly in that they comprise non-recyclable layers, or require the physical separation of extruded layers prior to recycling.

[0136] The tray according to the present invention has improved structural integrity. More specifically, the tray comprises a rib configuration which eliminates areas of void, i.e., without strengthening features, which constitute area of structural weakness. This is achieved without compromising the sustainability of the product, importantly without increasing the weight of the tray. Light-weight (low gauge) trays can be obtained which are strong. In fact, the weight of the tray can be decreased by up to 25% without affecting the structural strength of the tray.

[0137] Issues of warping and / or deformation may occur during the sealing of thin trays, in particular where high temperatures and / or pressures are applied to the tray. These issues may be exacerbated when the trays are made from materials with a low melting temperature and / or low glass transition temperature. For example, the preferred material, amorphous PET, has a glass transition temperature of around 67°C, and tends to warp and whiten under high temperature / high pressure conditions, such as those required during the sealing process.

[0138] In order to address these issues, the tray 1, 100 according to the present invention may comprise a layer of adhesive (not shown) on the upper, in use, surface of the peripheral flange 4 only. Preferably, the side walls 3 and base 2 are free of adhesive. Most preferably, the tray consists of amorphous PET and the layer of adhesive is applied on the flange 4 only. This configuration allows for the production of a tray which is fully recyclable into clear products, which are more desirable. The adhesive may be washed off prior to recycling the tray into the tray production process.

[0139] The adhesive may be an adhesive is a polymer-based material, for example a polyethylene based- or polyethylene copolymer based-material. The thickness of the layer of adhesive may be from 20 pm to 100pm.

[0140] The layer of adhesive may be selectively applied to the upper surface of the peripheral flange 4 by a roller, by spray coating, by a hot melt gun or by a printing technique. The roller may be a rubber or iron roller or a heated chrome roller.

[0141] In embodiments, the peripheral flange 4 is supported during the application of the layer of adhesive.

[0142] In embodiments, the layer of adhesive is cured or dried prior to the filling of the tray 1, 100 and sealing of the lidding film onto the flange 4.

[0143] In embodiments, the tray is corona treated or plasma treated, prior to the step of sealing the lidding film onto the peripheral flange of the tray.

[0144] A lidding film may be provided which may be sealed to the peripheral flange to create a sealed space between the base, side walls and lidding film. In embodiments, the lidding film is a multilayer film comprising at least a seal layer. In embodiments, the seal layer comprises or consists of polyethylene and / or polypropylene.

[0145] The overall thickness of the lidding film is preferably from 20 pm to 60 pm. The thickness of the seal layer is preferably from 15 pm to 50 pm.

[0146] Regarding the sealing conditions, in embodiments, the sealing temperature is from 110°C to 150°C, preferably 130°C. In embodiments, the sealing pressure is from 200 KPa to 1250 KPa.

[0147] Preferably, the sealing heat and / or pressure is applied for a period of for a period of 0.5 second to 1 second, to result in an efficient seal with minimal heat transfer to the flange.

[0148] In embodiments, the peripheral flange is supported during the step of sealing the lidding film onto the peripheral flange of the tray.

[0149] Without wishing to be bound by theory, when a tray 1,100 according to the present invention comprises a layer of adhesive on the flange 4 only, the heat transfers from the sealing bar through the lidding film to melt the layer of adhesive, thereby sealing the lidding film onto the flange 4. Thus, less heat is transferred to the (low gauge) flange, which is less likely to warp, deform and / or whiten.

[0150] The method according to the present invention may include the step of modifying or controlling the atmosphere within the sealed packaging. For example, the controlled or modified atmosphere may contain increased levels of oxygen or carbon dioxide.

[0151] The tray 1,100 according to the present invention may be nestable into another tray 1,100. In this embodiment, the side walls 3 extend substantially perpendicularly from base 2. If the side walls 3 were to extend strictly perpendicularly from the base 2, the walls 3 would be aligned and the trays cannot be nested.

[0152] The trays may be freely denestable from a stack of nested trays, so as to be fed onto a processing line. If more than one tray is fed at any one time, the whole processing line must be halted. When the trays are nested into one another, they are often difficult to separate because of the blocking properties of the material of the tray, for example PET, i.e., the propensity of PET surfaces to stick to other PET surfaces. Furthermore, when the upper surface of the peripheral flange 4 may be coated with an adhesive with a low tack at room temperature. As the temperature increases, the tack level also increases. The result of this would be the locking together (or partial gluing together) of trays as the underside of the denesting recess of a (top) tray contacts the upper flange of its nested (bottom) tray.

[0153] To address this issue, the tray according to the present invention may comprise at least one denesting recess 9 formed in a denesting area 10, where the denesting area 10 is relieved relative to the upper, in use, surface of the peripheral flange 4. The tray 1,100 according to the present invention may comprise one crescent-shaped denesting recess in a relieved denesting area 10. The tray 1, 100 may comprise a plurality of denesting recess 9 ina relieved denesting area 10. Alternatively (to the denesting recess(es)) or additionally, the denesting area 10 may comprise one or more denesting protrusions 110.

[0154] In a preferred embodiment, the tray comprises a plurality of denesting recesses and / or protrusions in a relieved denesting area. More preferably, the tray comprises two or three recesses (or two or three protrusions in a relieved denesting area. The denesting area may be located in a corner of the tray or may be located along a segment of a side wall. This configuration is different from conventional denesting recesses (as seen for example in Figure 1) which need to be formed at a precise softening point and under high form pressing. The windows of heat and forming pressure required to form the denesting configuration according to the present disclosure are wider, and the resulting denesting configuration is stronger and more dimensional stable than conventional denesting features. This is particularly advantageous in low gauge trays, such as the trays according to the present invention, which are still sufficiently strong to retain the required constant denesting air gap.

[0155] The denesting recess 9 and denesting area 10 are preferably free of adhesive. The relieved denesting area 10 extends partially or completely along the inner periphery of the flange 4 so that when the adhesive material is applied to the tray, the upper surface of the relieved area 10 is not coated. The denesting recesses 9 are located in the relieved area 10 so that when the adhesive material is applied to the tray 1,100, the upper surface of the denesting recess 9 and the denesting area 10 surrounding the recess 9 is not coated. As such the possibility of locking together the trays is eliminated. The height of the step between the flange 4 and the denesting area 10 can be altered to adjust the separation gap between the trays.

[0156] Thus, the present invention provides a tray that is economically produced, with minimal impact on the environment, and with enhanced structural integrity. The presence of structurally weak voids is eliminated to produce a light-weight, yet strong, tray which is less susceptible to damage. The present invention also provide a method for producing and sealing the tray with minimal risk of warping and deformation.Reference numerals1 Tray according to first embodiment2 Base3 Continuous side wall3 a Lateral side wall3b Longitudinal side wall4 Peripheral flange5 Spine6 Stiffening rib6 A First set of stiffening ribs6B Second set of stiffening ribs6C Third set of stiffening ribs7 Strengthening rib7a First strengthening rib7b Second strengthening rib7c Corner strengthening rib8 Strengthening protrusions (short ribs)9 Denesting recess10 Relieved denesting area100 Tray according to second embodiment103a Semi-circular side wall103b Longitudinal side wall106 Stiffening rib107a First strengthening rib107b Second strengthening rib107c Third strengthening rib108 Strengthening recesses110 Denesting protrusions

Claims

CLAIMS1. A tray comprising a base, a continuous side wall extending from the base, a peripheral flange extending along the upper, in use, edge of the continuous side wall, and a rib pattern, wherein the rib pattern comprises at least one spine and a plurality of stiffening ribs radially extending from the spine and wherein the width of the stiffening ribs is no more than 50 % of the width of the spine and / or wherein the height of the stiffening ribs is no more than 30% of the height of the spine.

2. The tray according to claim 1, wherein the width of the spine is from 2.0 mm to 3.0 mm.

3. The tray according to claim 1 or 2, wherein the width of the stiffening ribs is from 0.3 mm to 1.0 mm.

4. The tray according to any preceding claim, wherein the rib pattern comprises at least two strengthening ribs, at least one spine positioned longitudinally between the two strengthening ribs, and a plurality of stiffening ribs radially extending from the spine to one of the strengthening ribs.

5. The tray according to claim 4, wherein the strengthening ribs extend from a first side wall to a second side wall adjacent the first side wall.

6. The tray according to claim 4 or 5, wherein the width of the strengthening ribs is greater than the width of the spine.

7. The tray according to any preceding claim, wherein two or more stiffening ribs are substantially parallel to each other.

8. The tray according to any preceding claim, wherein the spine comprises one or more substantially linear sections, one or more curved sections and / or one or more undulated sections.

9. The tray according to any preceding claim, wherein one or more stiffening ribs comprises one or more substantially linear sections, one or more curved sections and / or one or more undulated sections.

10. The tray according to any preceding claim, wherein the base of the tray comprises four quadrants, and each quadrant comprises at least one rib pattern.

11. The tray according to any preceding claim, wherein the tray comprises or consists of polyethylene terephthalate, optionally of amorphous polyethylene terephthalate.

12. The tray according to any preceding claim, wherein the tray comprises a layer of adhesive on the upper, in use, surface of the peripheral flange.

13. The tray according to claim 12, wherein the thickness of the layer of adhesive is from 20pm to 100pm.

14. The tray according to any preceding claim, wherein the tray comprises at least one denesting recess formed in a denesting area, where the denesting area is relieved relative to the upper, in use, surface of the peripheral flange.

15. The tray according to claim 14, wherein the denesting recess and denesting area are free of adhesive.

16. A tray comprising a base, a continuous side wall extending from the base, a peripheral flange extending along the upper, in use, edge of the continuous side wall, and a rib pattern formed in the base and / or continuous side wall,wherein the rib pattern comprises at least two strengthening ribs, a spine extending longitudinally between the two strengthening ribs and a plurality of stiffening ribs radially extending from the spine to one of the strengthening ribs.

17. The tray according to claim 16, wherein the strengthening ribs extend from a first side wall to a second side wall adjacent the first side wall.

18. The tray according to claim 16 or 17, wherein the width of each strengthening rib is greater than the width of the spine.

19. The tray according to any one of claims 16 to 18, wherein the width of the spine is greater than the width of the ribs.

20. A packaging comprising a tray according to any one of claims 1 to 21 and a lidding film which may be sealed to the peripheral flange to create a sealed space between the base, side walls and lidding film.

21. The packaging according to claim 20, wherein the lidding film is a multilayer film comprising at least a seal layer.

22. The packaging according to claim 20 or 21, wherein the seal layer comprises or consists of polyethylene and / or polypropylene.

23. The packaging according to any one of claims 20 to 22, wherein the lidding film is sealed onto the peripheral flange and wherein the atmosphere within the sealed packaging is modified or controlled.

24. A method for manufacturing a tray according to any one of claims 1 to 19, comprising the step of thermoforming one or more trays from a sheet of plastic material.

25. The method according to claim 24, wherein the sheet of plastic material is a multilayer sheet.

26. The method according to claim 24 or 25, wherein the plastic material comprises or consists of polyethylene terephthalate, optionally of amorphous polyethylene terephthalate.

27. The method according to any one of claims 24 to 26, comprising the step of applying a layer of adhesive on the upper, in use, surface of the peripheral flange.

28. The method according to any one of claims 24 to 27, wherein the peripheral flange is supported during the application of the layer of adhesive.

29. The method according to any one of claims 24 to 28, wherein the method is a continuous process.

30. A method for forming a packaging according to any one of claims 20 to 23, providing a tray according to any one of claims 1 to 19; and providing a lidding film.

31. The method according to claim 30, comprising the step of manufacturing the tray using the method according to any one of claims 24 to 29.

32. The method according to claim 30 or 31, comprising the step of sealing the lidding film onto the peripheral flange of the tray.

33. The method according to claim 32, wherein the step of sealing the lidding film onto the peripheral flange of the tray includes the application of heat and / or pressure.

34. The method according to claim 35, wherein the sealing temperature is from 110°C to 150°C.

35. The method according to claim 33 or 34, wherein the heat and / or pressure is applied for a period of 0.5 second to 1.0 second.

36. The method according to any one of claims 33 to 25, wherein the peripheral flange is supported during the step of sealing the lidding film onto the peripheral flange of the tray.

37. The method according to any one of claims 33 to 36, wherein the container is corona treated or plasma treated, prior to the step of sealing the lidding film onto the peripheral flange of the tray.

38. The method according to any one of claims 33 to 37, comprising the step of modifying or controlling the atmosphere within the sealed container.

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