Method for manufacturing a 3-dimensional moulded fiber packaging unit, and such packaging unit

Abstract

The present invention relates to a method for manufacturing a 3-dimensional moulded fiber packaging unit and such packaging unit. The method according to the invention comprises the steps of: - preparing a mouldable fiber material; - forming the mouldable fiber material in a mould into a primary packaging unit with a compartment having a bottom and a sidewall; - providing a rim extending from the sidewall defining an opening to the compartment with an opening surface, and configured for receiving a sealing element, wherein the rim extends in an outwardly positive sealing angle relative to the opening surface; - releasing the primary packaging unit from the mould; and - drying the primary packaging unit and providing the 3-dimensional moulded fiber packaging unit.

Description

[0001] METHOD FOR MANUFACTURING A 3-DIMENSIONAU MOUEDED FIBER PACKAGING

[0002] UNIT, AND SUCH PACKAGING UNIT

[0003] The present invention relates to a method for manufacturing packaging units from fiber material, more specifically from mouldable fiber material. These packaging units from mouldable fiber material are three-dimensionally shaped to be capable of containing, storing, transporting and / or displaying a range of products, such as meat, cereals, eggs, snacks, fruits, vegetables, and other products including liquids and beverages. The 3 -dimensionally shaped packaging units may relate to containers, carriers, cases, cups, plates, boxes, trays, dividers et cetera. The moulded fiber packaging unit can be manufactured in a so-called wet moulding process with a pulp matrix optionally involving a foamed pulp matrix.

[0004] Conventional packaging units that are used in practice are formed in a moulding process and are provided with a bottom, side walls and often an edge or rim. Such rim extends from the side wall in a substantial horizontal direction. Rims are often kept relatively small and extend outwardly over an extension length of less than 2 mm. In such packaging units, the rim is often sufficiently stable under a range of conditions. One of the problems with these conventional packaging units the limited sealing area to attach a seal / film thereto. Rims having an increased extension length to provide sufficient sealing area often show rim sagging, especially during drying of the (conventional) packaging unit. This sagging renders it difficult to attach a seal / film to the rim.

[0005] The present invention has for its object to obviate or at least reduce one or more of the above stated problems in conventional packaging units.

[0006] For this purpose, the present invention provides a method for manufacturing a 3-dimensional rough moulded fiber packaging unit, wherein the method according to the invention comprising the steps of: preparing a mouldable fiber material; forming the mouldable fiber material in a mould into a rough moulded primary packaging unit with a compartment having a bottom and a side wall; providing a rim extending from the sidewall defining an opening to the compartment with an opening surface, and configured for receiving a sealing element, wherein the rim extends in an outwardly positive sealing angle relative to the opening surface; releasing the rough moulded primary packaging unit from the mould; and out-of-mould drying the rough moulded primary packaging unit and providing the 3- dimensional rough moulded fiber packaging unit.

[0007] The moulded fiber packaging unit that is manufactured in a method according to the present invention can be manufactured in a wet moulding process with a pulp matrix. In a wet moulding process the pulp matrix is provided to the moulds and after moulding the products are dried. Optionally, this may involve a foaming step to provide a foamed material to mould.

[0008] Preparing and providing a mouldable fiber material typically involves the providing of an amount of fiber material. This fiber material may have different origin, such as wood and / or nonwood fiber material, optionally from a recycling process such as from recycled paper material. Alternatively, or in addition to such paper material, the fiber material may also comprise an amount of non- wood fiber material to which is also referred to as natural and / or alternative fibers. Such fibers may involve biomass fibers from plant origin, examples of which are described in WO 2021 / 145764 Al. After preparing a mouldable fiber material, the (primary) packaging unit is formed in a mould. Such moulding involves the forming of the material into the desired shape of the (primary) packaging unit that typically has a compartment capable of carrying or holding a product, such as a food product including beverages.

[0009] After the forming process the (primary) packaging units are typically dried, optionally additionally involving an in-mould drying step. In a presently preferred embodiment of the invention the drying step involves an out-of-mould drying / heating operation that is optionally performed in an oven with the rough moulded primary packaging units being placed on one or more conveyor belts after taking the rough moulded primary packaging units from the mould(s). Preferably, the drying is done without any support or compressions, such as via mould(s). In particular, the rim remains substantially unsupported during the drying, therefor involving unsupported rim drying. In such case, the rims are unsupported or unconstrained during drying. It will be understood that further processing steps can also be performed. Such further processing steps may involve a second drying step and / or laminating steps. For example, during the drying of the rough moulded primary packaging unit, the sealing angle decreases / droops / sags, while maintaining a positive sealing angle.

[0010] The method according to the invention further involves the step of providing a rim extending from the side wall that defines an opening to the compartment with an opening surface. This compartment is capable of holding and maintaining products such as meat, cereals, eggs, snacks, fruits, vegetables, and other products including liquids and beverages.

[0011] The walls or sidewalls of the compartment of a packaging unit are preferably provided at an angle to the vertical, preferably at an angle in a range of 1.5° to 15.5°, more preferably in a range of 3.0° to 14.5°, even more preferably in the range of 4.0° to 10.0°, and most preferably this angle is about 6°. 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.

[0012] The rim that is provided in the method according to the invention is configured for receiving a sealing element. The rim extends in an outwardly positive sealing angle relative to the opening surface. Providing a positive sealing angle relative to the opening surface involves the rim extending outwardly in an upward direction when the packaging unit is in its "normal” position. Such positive sealing angle is preferably provided when forming the rough moulded primary packaging unit. This assures that the rim continues to have a positive sealing angle after the further processing steps, for example including a drying operation. Tests have shown that the positive sealing angle of the rim prevents undesired sagging of the rim, also for a rim extending from the side wall with a length larger than 2 mm.

[0013] The positive sealing angle is maintained in a positive angle during the drying of the rough moulded primary packaging unit in the presently preferred embodiments of the invention. A positive sealing angle preferably includes an angle of 0° as a positive sealing angle. As already indicated, during the out-of-mould drying of the rough moulded primary packaging unit, the sealing angle decreases / droops / sags, while maintaining a positive sealing angle. To maintain the sealing angle positive during and after drying, a somewhat larger sealing angle can be provided when forming the rough moulded primary packaging unit and providing the rim. In such case, even when the sealing angle becomes smaller due to a little sagging of the rim when drying the rough moulded primary packaging unit, the sealing angle maintains positive.

[0014] In a presently preferred embodiment of the invention, the sealing angle of the rough moulded primary packaging unit relative to the opening surface is provided in the range of 12.5° to 40°, more preferably in the range of 15° to 40°, and most preferably in the range of 20° to 30°.

[0015] Providing the sealing angle in one of the aforementioned ranges prevents the rim having a negative sealing angle when the packaging unit is in use. Tests have shown that this is even the case under unfavourable conditions, such as cold temperature and high humidity, as may occur in a fridge, for example. Involving a higher grammage of fibers for the packaging unit and / or longer fibers and / or applying a more gradual drying operation, such as a two-step drying operation, the sealing angle may be closer to the lower end point of the mentioned range(s), while in other situations the sealing angle may be more towards the upper end of the range(s).

[0016] In a further preferred embodiment of the invention, the method further comprises the step of sealing the opening surface with a sealing element.

[0017] Providing a sealing element to the packaging unit seals the products in the compartment of the packaging unit from the outside environment. This protects the products from undesired effects. Optionally, the sealing is performed after a little sagging of the rim has occurred, while maintaining a positive sealing angle for the rim. It is shown that this guarantees a robust and stable sealing of the sealing element to the rim of the packaging unit.

[0018] In a further preferred embodiment of the invention, the step of providing a rim comprises providing a rim length extending from the opening that is larger than 2.0 mm, preferably larger than 2.6 mm, and most preferably larger than 3.5 mm. Providing a rim having a rim length extending from the opening or side walls and having a length that is larger than the aforementioned lengths, provides an extended sealing surface so that sealing elements can be sealed effectively to the packaging unit. This may even provide the possibility to use different sealing materials that are possibly more sustainable. Depending on the specific material(s), such (more) sustainable sealing materials may require a larger sealing surface. Providing a positive sealing angle enables providing a larger rim length such that these advantages can be achieved.

[0019] In a further preferred embodiment of the invention, the step of providing a rim comprises providing a wall thickness of the rim in the range of 1.0 mm to 2.0 mm.

[0020] It is shown that providing a wall thickness of the rim in the aforementioned range provides a rim that is stable and robust under the relevant conditions and allows for a rim length that preferably extends from the side walls of more than 2.0 mm.

[0021] 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 (CO2), water, inorganic compounds and biomass. Preferably, the packaging unit resulting from 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). More preferably the compostability and the biodegradability is improved by allowing sealing material that is more sustainable and that can be applied due to the extended length of the rim.

[0022] 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 nonwood 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.

[0023] 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%, more preferably at least 50 wt%, even more preferably at least 80 wt%, even further more preferably at least 85 wt%, and most preferably at least 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.

[0024] 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.

[0025] 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 MFC is modified, e.g. the carboxyl groups are replaced by a hydrophobic group, the modified MFC 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.

[0026] 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, polyhdroxy alkanoate also referred to as PHA, for example including polyhdroxybutyrate also referred to as PHB and / or poly(3-hydroxybutyrate-co-3- hydroxyhexanoate) 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.

[0027] In one of the preferred embodiments of the invention the amount of biodegradable polyester in the mouldable 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%.

[0028] In a further embodiment of the invention the amount of biodegradable polyester in the moulded fiber matrix is in the range of 0.1 wt% to 12 wt%, 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 wt%.

[0029] 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.

[0030] 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.

[0031] The invention further relates to a manufacturing line for manufacturing a 3 -dimensional rough moulded fiber packaging unit configured for performing the method in an embodiment of the present invention.

[0032] Such manufacturing line provides the same or similar effects and / or advantages as described in relation to the method. Such manufacturing line comprises a moulding system for preparing the material and forming it into a rough moulded primary packaging unit. The manufacturing line further comprises a drying system, preferably an oven with one or more conveyor belts.

[0033] The invention further relates to a 3-dimensional rough moulded fiber packaging unit, the packaging unit comprising: a compartment having a bottom and a sidewall; and a rim extending from the sidewall defining an opening to the compartment with an opening surface, and configured for receiving a sealing element, wherein the rim extends in an outwardly positive sealing angle relative to the opening surface.

[0034] Such packaging unit provides the same or similar effects and / or advantages as described in relation to the method and / or manufacturing line. The packaging unit is preferably manufactured with the manufacturing method in an embodiment of the invention as described earlier.

[0035] The packaging unit according to the invention is preferably provided with one or more of the features that are described in relation to the method. Preferably, this includes one or more of the features associated with the sealing angle, the length of the rim, the wall thickness and the sealing element. More preferably, the sealing angle relative to the opening surface is in the range of 12.5° to 40°, more preferably in the range of 15° to 40°, and most preferably in the range of 20 to 30°. Also preferably, the length of the rim extending from the opening is larger than 2.0 mm, more preferably larger than 2.6, and most preferably larger 3.5 mm. Further, the wall thickness of the rim is preferably in the range of 1.0 mm to 2.0 mm. Further preferably, the packaging unit comprises a sealing element configured for sealing the opening surface of the packaging unit.

[0036] 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:

[0037] Figure 1A shows a packaging unit according to the present invention;

[0038] Figure IB shows the packaging unit of figure 1A with a sealing element:

[0039] Figures 2A-B show conventional packaging units having a sagging rim;

[0040] Figures 2C-D show a rim in the packaging unit according to the present invention having a positive sealing angle;

[0041] Figures 3A-C disclose different embodiments of packaging units having a rim with a positive sealing angle; and

[0042] Figure 4 shows the manufacturing method in an embodiment according to the present invention.

[0043] Packaging unit 2 (figures 1A-B) comprises bottom 4 and side wall 6. Side wall 6 comprises separate side walls or side wall parts 6a,b,c,d that are connected at corners 8 of packaging unit 2. Side walls 6 and bottom 4 define compartment 10 that is configured for holding and maintaining a product. Optionally, inner side walls can be provided with a laminate layer. Opening 12 is defined by rim 14 that extends in an outwardly direction from side wall 6. In the illustrated embodiment, the upper surface of rim 14 is provided with sealing edge 14a. Optionally, fibers 18 remain visible in side wall 6 and / or bottom 4.

[0044] Sealing element 20 (figure IB) can be provided to a packaging unit 22. Sealing element 20 provides additional protection for the products in compartment 10. In the illustrated embodiment, sealing element 20 is provided with pulling tab 21. Preferably, sealing element 20 and the sealing material as provided to sealing edge 14a that is configured for sealing sealing element 20 to rim 14 from a biodegradable material, and more preferably from a compostable material to improve the sustainable characteristics of packaging unit 2, 22.

[0045] Conventional packaging unit 52 (figures 2A-B) is provided with bottom 54 and sidewall 56, and having rim 514 extending over length LI. In use, rim 514 is subject to sagging (see figure 2B). It will be understood that this is a less appealing effect for a consumer and / or may damage a sealing element or the sealing thereof to the rim.

[0046] In the illustrated embodiment, Packaging unit 2, 22 (figures 2C-D) is provided with side walls 6 that are put at an angle y relative to the vertical, with angle y being preferably in the range of 1.5° to 15.5°. Rim 14 extends outwardly over length L from side wall 6 and is provided with a thickness d. Rim 14 is provided with a positive sealing angle relative to the horizontal.

[0047] Packaging units 2, 22 (figures 3A-C) are provided with positive sealing angle a, P (with an angle of 0° being considered a positive sealing angle. In the illustrated embodiments sealing angle a is defined relative to opening surface 16, and sealing angle refers to the surface of bottom 4. It will be understood that for most packaging units 2, 22 sealing angles a, P are equal. Providing a sealing angle a, P that is positive directly after the forming process prevents sagging of rim 14 in or after the drying operation, such that in use, rim 14 extends outwardly upwards, preferably horizontally and more preferably with a positive sealing angle such that rim 14.

[0048] Manufacturing process 102 (figure 4) comprises preparation step 104 wherein a pulp material is prepared. Preparation step 104 may involve applying and / or mixing wood fiber material and / or non-wood material such as alternative fibers. Wood material may involve so-called virgin fibers and / or fibers from recycled paper material, for example. This results in a slurry for a wet moulding process, optionally having a foaming agent to enable manufacturing a foamed packaging unit.

[0049] This pulp material 106 is then provided to forming step 108 wherein primary packaging 110 is moulded. Primary packaging 110 is then dried in drying step 112 resulting in dried packaging 114.

[0050] Dried packaging 114 can be subjected to one or more post-treatment processes 116 such as lamination processes thereby resulting in packaging unit 118 that corresponds to the illustrated packaging units 2, 22. Packaging unit 118 is filled with product(s) in filling step 120 resulting in (open) filled packaging unit 122, whereafter packaging unit 122 is sealed in sealing step 124 resulting in sealed packaging unit 126, 22.

[0051] Optionally, packaging unit 2, 22 is provided with alternative fiber material having fibers 18 that preferably remain visible for a consumer. This fiber material may relate to wood and nonwood fibers, such as the alternative fibers that are mentioned earlier. In some embodiments, the illustrated moulded fiber product 2, 22 comprises a moulded fiber material that is provided with an amount of MFC and / or biodegradable aliphatic polyester, such as PLA and / or PHBT. Optionally, an amount of calcium carbonate is applied.

[0052] In one of the tested embodiments, 3.8 wt% of MFC is applied in the moulded fiber product of the container body and rim 14, in combination with 3.7 wt% of biodegradable aliphatic polyester, in particular PHBT, and an amount of 1 wt% of calcium carbonate.

[0053] 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. A number of tests have been performed with different embodiments of container 2, 22. Optionally, further additional materials are being used, for example Xerolex (or BIM DS2801 as example of a dry strength agent) and / or AKD.

[0054] The tests showed a good sealing process. Furthermore, sealing element 20 remained on rim 14 during transport and storage, also under cold storage conditions. Therefore, packaging 2, 22 provided an effective and efficient sealed packaging.

[0055] 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.

Claims

CLAIMS1. Method for manufacturing a 3-dimensional rough moulded fiber packaging unit, comprising the steps of: preparing a mouldable fiber material; forming the mouldable fiber material in a mould into a rough moulded primary packaging unit with a compartment having a bottom and a side wall; providing a rim extending from the sidewall defining an opening to the compartment with an opening surface, and configured for receiving a sealing element, wherein the rim extends in an outwardly positive sealing angle relative to the opening surface; releasing the rough moulded primary packaging unit from the mould; and out-of-mould drying the rough moulded primary packaging unit and providing the 3- dimensional rough moulded fiber packaging unit.

2. Method according to claim 1 , wherein the out-of-mould drying is performed in an oven.

3. Method according to any of the foregoing claims, wherein the out-of-mould drying includes unsupported rim drying.

4. Method according to any of the foregoing claims, wherein during the out-of-mould drying of the rough moulded primary packaging unit the sealing angle decreases.

5. Method according to any of the foregoing claims, further comprising the step of maintaining the positive sealing angle during the drying of the rough moulded primary packaging unit.

6. Method according to any of the foregoing claims, wherein the sealing angle of the rough moulded primary packaging unit relative to the opening surface is provided in the range of 12.5° to 40°, more preferably in the range of 15° to 40°, and most preferably in the range of 20° to 30°.

7. Method according to any of the foregoing claims, further comprising the step of sealing the opening surface with the sealing element.

8. Method according to any of the foregoing claims, wherein the step of providing a rim comprises providing a rim length extending from the opening larger than 2.0 mm, preferably larger than 2.6 mm, and most preferably larger than 3.5 mm.

9. Method according to any of the foregoing claims, wherein the step of providing a rim comprises providing a wall thickness of the rim in the range of 1.0 mm to 2.0 mm.

10. Manufacturing line for manufacturing a 3-dimensional rough moulded fiber packaging unit configured for performing the method according to any of the foregoing claims.

11. Three-dimensional rough moulded fiber packaging unit, comprising: a compartment having a bottom and a side wall; a rim extending from the sidewall defining an opening to the compartment with an opening surface, and configured for receiving a sealing element, wherein the rim extends in an outwardly positive sealing angle relative to the opening surface.

12. Packaging unit of claim 11, wherein the sealing angle relative to the opening surface is in the range of 12.5° to 40°, more preferably in the range of 15° to 40°, and most preferably in the range of 20° to 30°.

13. Packaging unit of claim 11 or 12, wherein a length of the rim extending from the opening is larger than 2.0 mm, preferably larger than 2.6 mm, and most preferably larger than 3.5 mm.

14. Packaging unit according to claim 11, 12 or 13, wherein a wall thickness of the rim is in the range of 1.0 mm to 2.0 mm.

15. Packaging unit of any of foregoing claims 11-14, further comprising a sealing element sealing the opening surface.

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