NL2037353B1

NL2037353B1 - Method for manufacturing a packaging unit from a mouldable pulp material, packaging unit manufactured with such method and stack thereof

Info

Publication number: NL2037353B1
Application number: NL2037353A
Authority: NL
Inventors: Klaas Veenje Sandor
Original assignee: Huhtamaki Molded Fiber Tech Bv
Priority date: 2024-03-28
Filing date: 2024-03-28
Publication date: 2025-10-10
Also published as: EP4624660A1

Abstract

The invention relates to a method for manufacturing a packaging unit from a mouldable pulp material, a packaging unit manufactured with such method and a stack of these packaging units. The method for manufacturing a packaging unit from a mouldable pulp material comprises the steps of: - moulding a packaging unit comprising a product receiving or carrying compartment having a primary wall thickness; - providing the packaging unit with one or more vertical elements, wherein at least one of the one or more vertical elements has a product facing surface that extends in a substantially vertical direction; - performing a first drying step that at least dries the product facing surface, and compressing the wall thickness to an intermediate wall thickness with a compressing tool; and - performing a second drying step and providing a final wall thickness.

Description

METHOD FOR MANUFACTURING A PACKAGING UNIT FROM A MOULDABLE PULP

MATERIAL, PACKAGING UNIT MANUFACTURED WITH SUCH METHOD AND STACK

THEREOF

The invention relates to a method for manufacturing a moulded fiber packaging unit. These packaging units are made from moulded pulp material and are typically used to contain, store, transport, cover and/or display a range of products, such as food products. The packaging unit may relate to containers, carriers, covers, lids, cases, cups, plates, {rays et cetera.

The moulded fiber packaging unit can be manufactured in a wet moulding process with a pulp matrix, optionally involving a foamed pulp matrix, and/or can be manufactured in a dry laid process with a “fluffy” pulp matrix.

Conventional packaging units from moulded pulp material comprises a product receiving or carrying compartment configured for carrying and/or containing products. Typically, such packaging units have angled walls having angles of 6 degrees to 15 degrees relative to a vertical. In practice, such angles limit denesting possibilities, reduce clamp fit functionality and/or restrict the design freedom in the product receiving or carrying compartment.

Conventional solutions involve the provision of denesting features having sloping side surfaces involving relatively large stacking pitches such that the number of products in a stack is minimized. Also, conventional solutions often involve asymmetrical design features that typically involves a more complex (de)stacking operation. This increases transport and storage volume and/or cost.

The present invention has for its object to obviate or at least reduce one or more of the above stated problems in relation to conventional mould fiber packaging units and to provide a method for manufacturing such packaging units.

For this purpose, the present invention provides a method for manufacturing a packaging unit from a mouldable pulp material, the method comprising the steps of: — moulding a packaging unit comprising a product receiving or carrying compartment having a primary wall thickness; — providing the packaging unit with one or more vertical elements, wherein at least one of the one or more vertical elements has a product facing surface that extends in a substantially vertical direction; — performing a first drying step that at least dries the product facing surface, and compressing the wall thickness to an intermediate wall thickness with a compressing tool; and — performing a second drying step and providing a final wall thickness.

The moulded fiber packaging unit can be manufactured in a wet moulding process with a pulp matrix and/or can be manufactured in a dry laid process with a “fluffy” pulp matrix. In a wet moulding process the pulp matrix is provided to the mould(s), then formed in the mould, and after moulding the products are dried. Optionally, such process may involve a foaming step to provide a foamed material to the mould(s) to enable manufacturing a foamed fiber product. Alternatively, in a dry laid process, the pulp matrix can be supplied as sheets or reals that can be fed into a hammer mill, or similar device, also known as defibrator, that separates compressed rolls or sheets of the pulp into individual, loose fibers, which are then transported to the web forming system that forms the moulded fiber packaging unit. Typically, the dry-forming process requires a low energy consumption of 20 to 35% in comparison with wet-forming such that also the carbon footprint is significantly lower, with in some cases a higher production speed.

Preferably, the manufacturing method according to the present invention results in a biodegradable packaging unit, and even more preferably in a compostable packaging unit. In the context of this invention, degradable relates to degradation resulting in loss of properties, while biodegradable relates to degradation resulting from the action of microorganisms such as bacteria, fungi and algae. Compostable relates to degradation by biological process to yield carbon dioxide (CO), water, inorganic compounds and biomass. Preferably, the packaging unit resulting froom the manufacturing method of the present invention is home compostable (e.g. according to EN 13432:2000, EN 14046:2004 in Europe and AS 5810 "biodegradable plastics suitable for home composting” in Australia).

Packaging units from moulded fiber material have a wall thickness that may vary over the packaging unit. Unless stated otherwise, wall thickness relates to the average wall thickness of the relevant part of the packaging unit, such as a straight wall part, corner part, edge or rim part, bottom part, or another part of the packaging unit.

The method according to the present invention involves providing one or more vertical elements in a packaging unit, including one, two, three, four or any other suitable number of vertical elements. These vertical elements are configured for improving the functionality of the packaging unit.

For example, providing the vertical elements having a product facing surface that extends in a substantially vertical direction achieves or improves denesting functionality for the packaging unit.

For example, vertical elements that are provided as denesting elements achieve an improved denesting functionality due to the substantially vertical product facing surface thereof.

A further functionality that can be improved with the vertically extending surface of the vertical element is the improved clamping fit.

Even further, freedom of design for application of one or more inserts in the product receiving or carrying compartment is significantly improved.

Typical products that can be manufactured with an embodiment of the method according to the invention relate to (ready to eat) containers or trays, fruit or meat trays, liquid (juice) packages, butter tubs, liquid (coffee) cups, ice containers, egg trays, bottle dividers et cetera.

In the context of the present invention, substantially vertical relates to an angle of the vertically extending surfaces of the vertical element within the ranges of + 2 degrees relative to be vertical, more preferably at most +1 degrees, and most preferably at most to + 0.5 degrees. Preferably, when providing the packaging units with one or more vertical elements this preferably involves at least two or more vertical elements, more preferably each corner of the packaging unit is provided with a vertical element, wherein the vertical element on the inside of the packaging unit is provided with the product facing surface.

According to the method of the invention, when performing a first drying step, a few layers of the product facing surface of the vertical element are dried. This drying of the surface or surface layers of the vertical element achieves stability and firmness of this vertical element and enables prevention of undesired scraping in further processing steps. Experiments have shown that a higher dryness in the first drying step may increase the risk of undesired scraping in the further processing. Lower dryness values in the first drying step may result in a higher risk of delamination, the forming of undesired blisters in case of too much moisture in the second drying step, for example.

In the first drying step, a compression is achieved with a compression tool that reduces the wall thickness from a primary wall thickness after forming to an intermediate wall thickness after the first drying step. The final wall thickness is achieved after the second drying step that optionally may involve a second compressing step. However, in case the second drying step only involves drying and no further compression, it will be understood that the intermediate wall thickness after the first drying step will be the final wall thickness of the packaging unit manufactured by the method of the present invention. In case there is no or minimal compression in the second drying step the final wall thickness is closer to the intermediate wall thickness such that the wall thickness of the vertical element is probably somewhat larger. This larger wall thickness provides a larger contact surface of the vertical element in the stack of packaging unit such that the stack is more stable.

It will be understood that further process steps can be performed on the packaging units that are manufactured according to an embodiment of the method of present invention. An example of such further processing step is the lamination of the packaging unit with a laminate layer.

Examples of such laminate layer can be found in WO 2021/145764 Al.

Optionally, the second drying step in the manufacturing method also involves compressing the wall or wall parts of the packaging unit. In a first drying step, a first compression is performed, wherein the first drying step is responsible for a significant drying effect of the surfaces of the packaging unit as a whole and the surface(s) of the vertical element(s) in particular. In an embodiment wherein the second drying step also involves a further compression, especially the internal parts of the relevant parts of the packaging unit are compressed as these contain a higher moisture content as compared to the surface areas of these parts. This further compression can be performed, while undesired scraping of the surface areas is prevented or at least kept to a minimum as a result of drying the surface(s) in the first drying step.

In a presently preferred embodiment of the invention the method further comprises a step of heating the surface of at least one of the one or more vertical elements and/or the surface areas close to or adjacent to at least one of the one or more vertical elements.

Heating the surface area of the vertical element(s) and/or one or more of the surface areas close to or adjacent to such vertical element(s) improves the drying effect and in addition improves the effect of the compressing step(s). Preferably, the surface of the fiber layer was heated to make this surface rigid enough to survive the further processing steps and avoid undesired scraping.

Preferably, the product surface temperature in the first drying step is in the range of 180 to 200 °C, more preferably in the range of 180 to 190 °C. Also preferably, in a second drying step, the product surface temperature is in the range of 170 to 200 °C, more preferably 180 to 190 °C.

The time duration of the first drying step is preferably in the range of 6 to 7 seconds, and in the second drying step preferably in the range of 6 to 10 seconds. However, it will be understood that the actual duration depends on grammage and moisture content of the packaging unit.

In one of the presently preferred embodiments of the invention, compressing the intermediate wall thickness to the final wall thickness of the packaging unit is performed with a second compressing tool. The dimensions of the second compressing tool may be somewhat larger, as compared to the first compressing tool that is used in combination with the first drying step, such that further compression is achieved. In an alternative, and presently preferred, embodiment of the invention, the intermediate wall thickness is compressed to the final wall thickness with the first compressing tool being configured for radial expansion. Providing the first compressing tool with radial expansion elements, the compressing can be performed in a radial direction effectively, without having to introduce different tooling.

In a presently preferred embodiment of the invention at least one of the drying steps is performed in a mould.

Performing the first and/or second drying step in a mould enables so-called in-mould drying.

This provides an effective process for drying the packaging unit. In one of the presently preferred embodiments of the invention, the manufacturing method comprises the step of performing the first and second drying steps in the mould that is also used for forming the packaging unit.

In a presently preferred embodiment of the invention the final wall thickness is in the range of 0.5 mm to 1.5 mm, more preferably in the range of 0.75 mm to 1.2 mm, and is most preferably about 1.0 mm.

After forming the wall thickness of the “wet” or dry laid product is typically about 2.0 mm. It 5 will be understood that other thicknesses can also be envisaged in accordance with the present invention, and the wall thickness may also depend on the actual design and desired properties of the packaging unit. For example, final wall thicknesses may also be in the range of 0.6 mm to 1.2 mm, being most preferably about 0.9 mm.

In one of the presently preferred embodiments of the invention the mouldable pulp material comprises fiber material that optionally comprises an amount of non-wood fiber material. The non- wood fiber material is also referred to as natural and/or alternative fiber material. Providing an amount of these fibers provides a natural feel to the moulded fiber packaging unit and/or improves the overall strength and stability of the moulded fiber packaging unit. Such non-wood fibers may comprise fibers from different origin, specifically biomass fibers from plant origin. Examples of this biomass of plant origin are described in the aforementioned WO 2021/145764 Al.

In a presently preferred embodiment of the moulded fiber packaging unit that is manufactured with a method of the present invention, the non-wood fiber material provides at least 5 wt of the fiber material of the packaging unit, preferably at least 10 wt%, preferably at least 50 wt%, even more preferably at least 80 wt%, even further more preferably at least 85 wt%, and most preferably atleast 92.5 wt%. It was shown that moulded fiber packaging units can be manufactured effectively from the non-wood fiber material having such significant amounts of non-wood fiber material.

In a presently preferred embodiment of the invention the mouldable fiber material comprises an amount of non-wood fibers, wherein at least 80 percent of the fibers has a length above 1.1 mm, preferably a length above 1,2 mm. This provides a significant length increase of the fibers that are provided in the moulded pulp material as compared to most conventional packaging units. This results in an increased strength-weight ratio for the packaging unit.

In a presently preferred embodiment of the invention, the mouldable fiber material comprises an amount of microfibrillated cellulose (MFC). In the context of the present invention this may also include nanofibrillar cellulose or cellulose nanofibers or nanocellulose. MFC preferably originates from cellulose raw material of plant origin. The use of MFC enhances the fiber-fiber bond strength and further improves the reinforcement effect in the matrix. In such embodiment of the invention, MFC provides improved barrier properties. Also, MFC may fill the gaps between the fibers and, therefore, has gas barrier properties, for instance an enhanced oxygen barrier. When

MEC is modified, e.g. the carboxyl groups are replaced by a hydrophobic group, the modified

MEC can enhance also the water vapor barrier. As a further advantage, a paper look and/or paper feel surface layer can be provided or improved. This paper look and/or paper feel surface layer contributes to the consumer’s appreciation of the container that is manufactured with a method according to the invention.

In a further preferred embodiment of the invention the mouldable fiber material comprises an amount of biodegradable polyester. Preferably, the biodegradable polyester is a biodegradable aliphatic polyester, a biodegradable aromatic polyester, and/or a biodegradable aromatic-aliphatic polyester. It is noted that a biodegradable aliphatic-aromatic polyester comprises an aromatic part and an aliphatic part. The biodegradable polyester can be provided in the matrix of pulp material of the packaging unit and/or in one or more laminate layers. The biodegradable polyester may relate to poly(butylene succinate) also referred to as PBS, polybutylene sebacate terephthalate also referred to as PBST, polyhdroxyalkanoate also referred to as PHA, for example including polyhdroxybutyrate also referred to as PHB and/or poly(3-hydroxybutyrate-co-3-hdroxyhexanoate) also referred to as PHBH and/or poly(3-hydroxybutyrate-co-3-hydrovalerate) also referred to as

PHBV, polycaprolactone also referred to as PCL, poly(lactic acid) also referred to as PLA, poly(glycolic acid) also referred to as PGA, polybutyleneadipate-terephthalate also referred to as

PBAT and also known with its commercial name ecoflex, and/or other suitable components, such as poly(alkylene dicarboxylate) other than PBS, PBAT and PBST, poly(lactic-co-glycolic acid) also referred to as PLGA, including mixtures or blends. It is noted that for example PBAT and

PBST comprise an aromatic part and aliphatic part. Therefore, PBAT and PBST may also be referred to as biodegradable aliphatic-aromatic polyester (or biodegradable aromatic polyester). An example of a blend is a blend of PBAT and PLA, also known with its commercial name Ecovio, or a blend of PBAT and PBS, or another suitable blend that is preferably home compostable. In some of the presently preferred embodiments of the invention the biodegradable polyester is bio-based.

In one of the preferred embodiments of the invention the amount of biodegradable polyester in the moulddable fiber material for the packaging unit is in the range of 0.5 wt% to 20 wt%, preferably in the range of 1 wt% to 16 wt%. more preferably in the range of 1 wt% to 15 wt%, even more preferably in the range of 2 wt% to 10 wt%, even more preferably in the range of 5 wt% to 9 wt%, and most preferably in the range of 6.5 wt% to 8 wt%.

In a further embodiment of the invention the amount of biodegradable polyester in the moulded fiber matrix is in the range of 0.1 wi% to 12 wit%, preferably in the range of 0.5 wt% to 8 wt%, more preferably in the range of 1 wt% to 5 wt%, and is most preferably in the range of 2 wt% to 4 wide.

By applying an amount of biodegradable polyester in one of the aforementioned ranges, the sustainability and packaging characteristics of the packaging units resulting from the manufacturing method according to the present invention are significantly improved. For example, applying an amount of biodegradable polyester in these aforementioned ranges provides packaging units that are both stable and strong, and further improves the denesting properties of the packaging units in combination with vertical elements acting as denesting elements. Another advantage when using biodegradable polyester in a packaging unit is the constancy of size or dimensional stability.

In a further embodiment of the invention the biodegradable polyester in the mouldable fiber material comprises fibers that preferably have a length of above 1.2 mm. Providing fibers of the biodegradable polyester achieves a network of moulded and biodegradable polyester fibers in the moulded fiber product. This further improves the strength of the packaging unit.

The invention further relates to packaging unit from a moulded pulp material, the packaging unit comprising: — a product receiving or carrying compartment having one or more walls; and — one or more vertical elements, wherein the vertical element has a product facing surface that extends in a substantially vertical direction.

The packaging unit provides the same or similar effects as described in relation to the manufacturing method. As already explained the packaging unit can be manufactured using wet forming techniques that optionally includes a foaming step. In other embodiments of the invention the packaging unit is provided using dry forming techniques. In the manufacturing process suitable (alternative) non-wood fibers can be applied. Also, optionally in combination, suitable biodegradable polyesters can be used, as already mentioned in relation to the manufacturing method.

Preferably, the packaging unit comprises two or more vertical elements, and even more preferably in case of a packaging unit comprising some corners, each of these corners is provided with a vertical element. In some of the presently preferred embodiments of the invention, the vertical elements act as a denesting element. More specifcially, the one or more vertical elements are configured for enabling denesting the packaging unit from a stack of packaging units.

The vertical element is provided with a substantially vertical extending surface in one of the ranges as mentioned earlier in relation to the respective method step. The further walls of the compartment of the packaging unit are preferably provided at an angle to the vertical under an angle in a range of 1.5 to 15.5 degrees, preferably in a range of 3.0 to 14.5 degrees, mor preferably in the range of 4.0 to 10.0 degrees, and most preferably about 6 degrees. In the context of the present invention, such an angle relates to the (average) angle at a middle or central part of the respective wall part of the packaging unit.

The invention further also relates to a stack of packaging units in one of the embodiments of the present invention.

The stack of packaging units provides the same or similar effects as described in relation to the manufacturing method and/or packaging unit of the invention.

In such stack two adjacent packaging units are provided with a gap between the side walls in the range of 0.2 mm to 3.5 mm, preferably in the range of 0.4 mm to 2.5 mm, more preferably in the range of 0.45 to 1.5 mm, and is most preferably about 0.5 mm.

Preferably, two adjacent packaging units are provided at a pitch in the range of 1.0 mm to 8.0 mm, preferably in the range of 1.5 mm to 6.5 mm, more preferably in the range of 2.5 mm to 5.5 mm, and is most preferably about 4.5 mm.

Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which: — Figure 1 shows a packaging unit in an embodiment according to the present invention; — Figures 2A-B show further views of the packaging unit of figure 1; — Figures 3A-B show a stack of packaging units in an embodiment according to figure 1; — Figures 4A-B show further alternative embodiments of a packaging unit according to the present invention; and — Figure 5 shows a schematic overview of processing steps in an embodiment of the manufacturing method according to the present invention.

Packaging unit 2 (figures 1, 2A-B, 3A-B) comprises outer side wall 4 with a number of outer corners 6 and outer end walls 8. One (upper) side of packaging unit 2 is open and is provided with rim 10 that provides access to compartment 12. Compartment 12 is defined by inner side walls 14, inner corners 16, and inner end walls 18. In the illustrated embodiment, at each corner 6, 16 vertical element 20 is provided. Optionally, compartment 12 of packaging unit 2 is provided with laminate layer 50.

Packaging unit 2 is provided with length L, width W, and height H (figures 2A-B). Inner corner 16 has radius Ri and outer corner 6 has outer radius Ro. In the illustrated embodiment vertical element 20 is provided with height hq. In the illustrated embodiment, length L is about 131 mm, width W is about 95 mm, and height H is about 43 mm. It will be understood that other dimensions of packaging unit 2 can also be envisaged in accordance to the present invention. This also applies to the specific shape of packaging unit 2.

Stack 52 of packaging units 2 (figures 3A-B) shows packaging units having respective side walls at distance Dw. In the illustrated embodiment Dw is about 0.2 mm (figure 3A) and the wall angle of a, is about 10 degrees relative to the vertical. At corner 6, 16 (figure 3B) distance Dc between two adjacent corner parts is about (0.5 mm and corner wall angle a. is about 14 degrees relative to the vertical. Vertical element 20 comprises vertical wall 24 that is at an angle o; of about 90 degrees relative to rim 10. Stacking pitch he between two adjacent packaging units 2 is in the illustrated embodiment about 4.6 mm. At corners 6, 16 radius r between wall part 6, 16 and bottom part 22 is about 3.4 mm.

In stack 52 (figures 3A-B), contact surface 26 of vertical element 20 contacts the respective counter surface 26 of the adjacent packaging unit 2. lt will be understood that a larger wall thickness of vertical element 20 will enlarge this contact surface 26, thereby providing more stability and rigidity to vertical element 20, packaging unit 2 and stack 52. In the illustrated embodiment bottom 22 has an elevated part with an elevation hy, of about 2.1 mm.

In an alternative embodiment, packaging unit 102 (figure 4A) is a cup-shaped packaging unit having bottom diameter Db, top diameter Dt, and height He. Packaging unit 102 comprises side wall 104 that is provided at an angle o, to the vertical. Furthermore, packaging unit 102 is provided with compartment 106, opening 108 that is defined by rim 110 and edge 112. At the circumference of rim 110 there is provided a number of vertical elements 114 having outer vertical wall 116.

Edge 112 is provided with height hr and first vertical element 114 extends over height hg of edge 112 and further over distance ha into compartment 106. It will be understood that other dimensions and shapes can also be envisaged in accordance with the present invention.

In the illustrated embodiment, vertical element 114 of packaging unit 102 is provided with upper radius Ru and lower radius or Rl, wherein Rl is larger than Ru such that in a stack of packaging units 102 vertical elements 114 will not be pressed into each other. This prevents that adjacent packaging units 102 remain fixated to each other.

Optionally, sip lid 122 (figure 4B) can be provided which is illustrated in a regular design.

Optionally, sip lid 122 is snapped around edge 110, and preferably around vertical elements 114, specifically around outer wall 116 such that in this illustrated embodiment edge 124 of sip lid 122 snaps or clamps around surface 126 (figure 4A) of vertical element 114. It will be understood that this is one of the possible examples of sip lid 122 that can be manufactured in accordance with the present invention. Alternatively, or additionally, sip lid 122 can also be provided with one or more vertical elements 126.

Optionally, packaging unit 2, 102 is provided with alternative fiber material having fibres 128 that preferably remain visible for a consumer. This fiber material may relate to wood and non- wood fibres, such as the alternative fibres that are mentioned earlier. In some embodiments, the illustrated moulded fiber product 2, 102, 122 comprises a moulded fiber material that is provided with an amount of MFC and/or biodegradable aliphatic polyester, such as PLLA and/or PHBT.

Optionally, an amount of calcium carbonate is applied.

In one of the tested embodiments, 3.8 wt% of MFC is applied in the moulded fiber product of the cup-like container body and flange, in combination with 3.7 wt% of biodegradable aliphatic polyester, in particular PHBT, and an amount of 1 wt% of calcium carbonate.

Examples with and without the use of non-wood fiber material have been tested. In some of these examples an amount of soya fibers and/or rice husks and/or almond or coconut shells is applied in the plant-based fiber material. In such moulded fiber product fibers originating from wood are combined with an amount of about 45 wt% to 55 wt% of alternative fibers. Preferably, an amount of alternative non-wood fiber material is included wherein the fibers remain visible on the surface of the moulded packaging unit. This is illustrated with fibers 128 that are preferably present on the outer surface of packaging units 2, 102 A number of tests have been performed with different embodiments of container 2, 22, 42,62. Optionally, further additional materials are being used, for example Xerolex (or BIM DS2801 as example of a dry strength agent) and/or AKD.

Furthermore, laminate layer 50 can be provided to packaging units 2, 102 to provide improved functionality. Examples of laminate layers that can be applied are described in the aforementioned

WO 2021/145764 Al. According to one of the presently preferred embodiments of the present invention, lamination layer 50 comprises at least five material layers. It will be understood that additional layers can also be provided in accordance with the present invention. In such embodiment the inner and outer cover layer may comprise an amount of a biodegradable aliphatic polyester, such as poly(butylene succinate) also referred to as PBS, and/or one or more of the other suitable polyesters that were mentioned earlier in this description. This improves the surface properties of the biodegradable (laminated) multi-layer, and also of any packaging unit provided therewith, such as the so-called wipeability, possibilities for masking (hiding) undesirable stains and/or promoting the compostable effect of the packaging unit, grease resistance, reduction penetration of oil originating from the food product, improving water barrier properties, reducing ridging problems. In addition, the (laminated) multi-layer preferably comprises a functional (central) layer that comprises a biodegradable and compostable polyvinyl alcohol, also referred to as a vinyl alcohol polymer, including co-polymers. This functional layer contributes to the multi- layer properties, such as acting as a gas barrier. For example, the functional layer may provide an effective oxygen (O2) barrier. This improves shelf-life of the food product(s) in the packaging unit.

In the illustrated embodiment the vinyl alcohol polymer comprises a highly amorphous vinyl alcohol polymer (HAVOH), such as butandiol vinyl alcohol co-polymer (BVOH). Such polymer or polymer mixture also provides an effective barrier, especially a gas barrier, and more specifically an oxygen (O2) barrier. Such barrier can effectively be used to further improve the shelf-life of the food product(s) and reduce food waste. In experiments a surprisingly effective oxygen (O2) barrier was achieved, especially at relative humidities up to 60% as compared to conventional materials.

An example of BVOH is G-Polymer. The inner and outer cover layers are preferably separated from the central functional layer by an intermediate layer, to which can also be referred to as a tie layer. Such intermediate layer is substantially of a biodegradable material and connects and/or seals its adjacent layers.

As an alternative or in addition to providing laminate layer 50, the inside of packaging units 2, 102 can be provided with inner coating 50, while the outer surface is optionally provided with outer coating 51. In some of the illustrated embodiments coatings are provided as a silicon-based coating that preferably comprises a silicon oxide, in particular a silicon dioxide. In one of the illustrated embodiments sealing lid 122 is also provided with the same coating. For example, a coating of silane, graphene, chitosan, alginate, wax, polyethylene, silica gel can also be envisaged.

It will be understood that also different coatings and/or a combination of laminate layer(s) and coating(s) can be envisaged in accordance with the present invention.

When manufacturing packaging unit 2, 102 (figure 5), manufacturing process 202 comprises a number of steps. In preparation step 204 the raw material is prepared. Depending on the techniques that are used, this may include sub-steps as mixing, adding additives, hammering, refining, foaming etc.. In the case of dry forming, optionally a blanket or sheet material is provided in sheet preparing step 206. From steps 204, 206 packaging unit 2, 102 is formed or moulded in moulding step 208 that may also include forming of the packaging unit. This moulding step 208 involves providing the packaging unit with a primary wall thickness and a number of vertical elements 20, 114, wherein the respective surface extends in a substantially vertical direction. After moulding first drying step 210 is performed, optionally after performing pre-heating step 211. Compressing step 212 preferably comprises inserting first compression tool into the compartment of packaging unit 2, 102. Optionally, first drying step 210 and compressing step 212 are performed simultaneously and/or are integrated. In some of the experiments, time duration of first drying step 210 with integrated compressing step 212 is about 7.5 seconds, depending on the actual wall thickness. As a next step, second drying step 214 is performed, optionally after pre-heating step 216. Second compression step 218 is preferably integrated and performed simultaneously with second drying step 214. Drying steps 210, 214 are optionally performed in a mould, relating to so- called in-mould drying. After the second drying step 214 and optional second compression step 218, further processing steps 220 can be performed. Such further processing steps 220 may include lamination, for example.

The present invention is by no means limited to the above described preferred embodiments thereof. The rights sought are defined by the following claims within the scope of which many modifications can be envisaged.

CLAUSES

1. Method for manufacturing a packaging unit from a mouldable pulp material, the method comprising the steps of: — moulding a packaging unit comprising a product receiving or carrying compartment having a primary wall thickness; — providing the packaging unit with one or more vertical elements, wherein at least one of the one or more vertical elements has a product facing surface that extends in a substantially vertical direction; — performing a first drying step that at least dries the product facing surface, and compressing the wall thickness to an intermediate wall thickness with a compressing tool; and — performing a second drying step and providing a final wall thickness. 2. Method according to clause I, further comprising the step of heating the surface of at least one of the one or more vertical elements and/or the surface areas close to or adjacent to at least one of the one or more vertical elements. 3. Method according to clause 1 or 2, wherein compressing the intermediate wall thickness to the final wall thickness is performed with a second compressing tool. 4. Method according to clause 1 or 2, wherein compressing the intermediate wall thickness to the final wall thickness is performed with the first compressing tool that is configured for radial expansion, 5. Method according to any of the foregoing clauses, wherein at least one of the drying steps is performed in a mould. 6. Method according to the foregoing clause, wherein the first and the second drying steps are performed in the mould. 7. Method according to any of the foregoing clauses, wherein the final wall thickness is in the range of 0.5 mm to 1.5 mm, preferably in the range of 0.75 mm to 1.2 mm, and is most preferably about 1.0 mm.

8. Packaging unit from a moulded pulp material, the packaging unit comprising:

— a product receiving or carrying compartment having one or more walls; and

— one or more vertical elements,

wherein the vertical element has a product facing surface that extends in a substantially vertical direction.

9. Packaging unit according to the foregoing clause, wherein two or more vertical elements are provided.

10. Packaging unit according to clause 8 or 9, wherein the one or more vertical elements are configured for enabling denesting the packaging unit from a stack of packaging units.

11. Packaging unit according to any of the foregoing clauses 8-10, wherein the product receiving or carrying compartment comprises a number of corners, and wherein each corner is provided with a vertical element.

12. Packaging unit according to any of the foregoing clauses 8-11, wherein one or more walls of the compartment are provided at an angle to the vertical in the range of 1.5 to 15.5 degrees, preferably in the range of 3.0 to 14.5 degrees, more preferably in the range of 4.0 to 10.0 degrees,

and is most preferably about 6 degrees. 13. Stack of packaging units according to any of the foregoing clauses 8-12. 14. Stack according to the foregoing clause, wherein two adjacent packaging units are provided with a gap between the side walls in the range of 0.2 mm to 3.5 mun, preferably in the range of 0.4 mm to 2.5 mm, more preferably in the range of 0.45 to 1.5 mm, and is most preferably about 0.5 mm. 15. Stack according to any of the foregoing clauses 13-14, wherein two adjacent packaging units are provided at a pitch in the range of 1.0 mm to 8.0 mm, preferably in the range of 1.5 mm to 6.5 mm, more preferably in the range of 2.5 mm to 5.5 mm, and is most preferably about 4.5 mm.

Claims

CONCLUSIONS

1. A method of manufacturing a packaging unit from a mouldable pulp material, the method comprising the steps of: — forming a packaging unit comprising a compartment for carrying and/or receiving a product, having a primary wall thickness; — providing the packaging unit with one or more vertical elements, at least one of the one or more vertical elements having a product-facing surface extending in a substantially vertical direction; — performing a first drying step which dries at least the product-facing surface, and compressing the wall thickness to a compressed wall thickness with a compression tool; and — performing a second drying step and providing a final wall thickness.

2. The method of claim 1, further comprising the step of heating the surface of at least one of the one or more vertical elements and/or the surface close to or adjacent to at least one of the one or more vertical elements.

Method according to claim 1 or 2, wherein the compressing of the compressed wall thickness to the final wall thickness is carried out with a second compression tool.

4. The method of claim 1 or 2, wherein compressing the compressed wall thickness to the final wall thickness is performed with the first compression tool configured for radial expansion.

5. A method according to any preceding claim, wherein at least one of the drying steps is carried out in a mold.

6. A method according to the preceding claim, wherein the first and second drying steps are carried out in the mold.

7. A method according to any preceding claim, wherein the final wall thickness is in the range of 0.5 mm to 1.5 mm, preferably in the range of 0.75 mm to 1.2 mm, and most preferably about 1.0 mm.

8. Packaging unit made of moulded pulp material, the packaging unit comprising: — a compartment for carrying and/or receiving a product, provided with one or more walls and a product-facing surface; and — one or more vertical elements, at least one of the vertical elements having a product-facing surface extending in a substantially vertical direction.

9. Packaging unit according to the preceding claim, wherein two or more vertical elements are provided.

10. Packaging unit according to claim 8 or 9, wherein the one or more vertical elements are adapted to de-nest the packaging unit from a stack of packaging units.

A packaging unit according to any preceding claim, wherein the compartment for carrying and/or receiving a product comprises a plurality of corners, and wherein each corner is provided with a vertical element.

A packaging unit according to any one of the preceding claims 8-11, wherein one or more walls of the compartment are provided at an angle to the vertical in the range of 1.5 to 15.5 degrees, preferably in the range of 3.0 to 14.5 degrees, more preferably in the range of 4.0 to 10.0 degrees, and most preferably about 6 degrees.

13. Stack of packaging units according to any of the preceding claims 8-12.

A stack according to the preceding claim, wherein two adjacent packaging units are provided with a gap between the side walls in the range of 0.2 mm to 3.5 mm, preferably in the range of 0.4 mm to 2.5 mm, more preferably in the range of 0.45 to 1.5 mm, and most preferably about 0.5 mm.

A stack according to any one of the preceding claims 12-14, wherein two adjacent packaging units are provided with a pitch in the range of 1.0 mm to 8.0 mm, preferably in the range of 1.5 mm to 6.5 mm, more preferably in the range of 2.5 mm to 5.5 mm, and most preferably about 4.5 mm.