Method for Producing a Moulded Pulp Material for Packaging Unit and Such Packaging Unit

Abstract

The present invention relates to a method for producing a moulded pulp material that is suitable for manufacturing of a packaging unit and such packaging unit. The method of the invention comprises the steps of: - preparing a raw moulded pulp material; - providing the raw moulded pulp material to an extruder; - extruding the raw moulded pulp material; - adding one or more additives; and - providing the moulded pulp material at the outlet of the extruder.

Claims

1-24. (canceled)

25. A method for producing a moulded pulp material for a packaging unit, the method comprising the steps of: preparing a raw moulded pulp material; providing the raw moulded pulp material to an extruder; extruding the raw moulded pulp material; adding one or more additives; and providing the moulded pulp material at the outlet of the extruder.

26. The method according to claim 25, wherein the additives comprise a pigment.

27. The method according to claim 26, wherein the pigment is added after adding a fixative.

28. The method according to claim 25, further comprising the step of selecting one or more dimethylamine polymers as fixative.

29. The method according to claim 25, wherein the weight ratio of additive to fixative is in the range of 2-25, preferably in the range of 3-20, and most preferably in the range of 4-19.

30. The method according to claim 25, wherein the raw moulded pulp material comprises a mixture of soft wood and hard wood, and/or comprising the step of providing an amount of natural and/or alternative fibers.

31. The method according to claim 25, further comprising the step of adding an amount of a biodegradable aliphatic polyester, wherein the amount of biodegradable aliphatic polyester in the moulded pulp material is preferably in the range of 0.5-20 wt.%, more preferably in the range of 1-15 wt.%, even more preferably in the range of 2-10 wt.%, even more preferably in the range of 5-9 wt.%, and most preferably in the range of 6.5-8 wt.%, wherein the biodegradable aliphatic polyester preferably comprises an amount of one or more of PBS, PHB, PHA, PCL, PGA, PHBH and PHBV.

32. The method according to claim 25, further comprising the step moulding a packaging unit, further comprising the step of: providing a laminated multi-layer comprising: an inner cover layer comprising an amount of a biodegradable aliphatic polyester; a first intermediate layer of a biodegradable material for connecting and/or sealing adjacent layers; a functional layer comprising a vinyl alcohol polymer; a second intermediate layer of a biodegradable material for connecting and/or sealing adjacent layers; and an outer cover layer comprising an amount of a biodegradable aliphatic polyester, and manufacturing the packaging unit with the laminated multi-layer to provide a food packaging unit that is a compostable packaging unit.

33. The method according to claim 32, further comprising the step of providing a biodegradable top seal film.

34. The method according to claim 32, further comprising the step of performing (dry) sterilisation and pasteurisation of the packaging units.

35. The method according to claim 32, further comprising the step of biodegrading the packaging unit, wherein the decomposing is performed at a temperature in the range of 5 to 40° C., preferably in the range of 10 to 30° C., more preferably in the range of 15 to 25° C., and most preferably at a temperature of about 20° C.

36. A packaging unit from a moulded pulp material, the packaging unit comprising a food receiving and/or carrying compartment, wherein the moulded pulp material is provided by a method according to claim 25.

37. The packaging unit according to claim 35, wherein the moulded pulp material comprises an amount of fibers, wherein at least 80% of the fibers has a length above 1.1 mm, preferably above 1.2 mm.

38. The packaging unit according to claim 35, wherein the moulded pulp material comprises a pigment and a fixative, wherein the weight ratio of pigment to fixative is in the range of 2-25, preferably in the range of 3-20, and most preferably in the range of 4-19.

39. The packaging unit according to claim 35, wherein the fixative comprise dimethylamine polymers.

40. The packaging unit according to claim 35, further comprising a biodegradable laminated multi-layer, with the multi-layer comprising: an inner cover layer comprising an amount of a biodegradable aliphatic polyester; a first intermediate layer of a biodegradable material for connecting and/or sealing adjacent layers; a functional layer comprising a vinyl alcohol polymer; a second intermediate layer of a biodegradable material for connecting and/or sealing adjacent layers; and an outer cover layer comprising an amount of a biodegradable aliphatic polyester, and wherein the packaging unit is a compostable packaging unit, wherein the thickness of the individual layers is within the range of 5-50 .Math.m, preferably in the range of 5-30 .Math.m, and wherein the total thickness of the laminated multi-layer is in the range of 20-150 .Math.m.

41. The packaging unit according to claim 40, wherein the laminated multi-layer is a co-extruded laminated multi-layer, wherein the laminated multi-layer is melted or fused with the compartment, wherein the packaging unit comprises a layer of biodegradable aliphatic polyester on a product contact surface to improve melting or fusing of the laminated multi-layer thereon, wherein the laminated multi-layer is melted in the moulded pulp material matrix.

42. The packaging unit according to claim 35, further comprising a biodegradable top seal film, wherein the packaging unit comprises a circumferential edge comprising a connecting surface for the top seal film that is substantially free of the laminated multi-layer, and wherein the top seal film comprising a biodegradable aliphatic polyester.

43. A method for producing a moulded pulp material for a packaging unit, the method comprising the steps of: preparing a raw moulded pulp material; providing the raw moulded pulp material to an extruder; extruding the raw moulded pulp material; adding one or more additives; and providing the moulded pulp material at the outlet of the extruder, wherein the additives comprise a pigment, wherein the pigment is added after adding a fixative, wherein the weight ratio of additive to fixation is in the range of 2-25.

44. The method according to claim 43, further comprising the step of adding an amount of a biodegradable aliphatic polyester, wherein the amount of biodegradable aliphatic polyester in the moulded pulp material is in the range of 0.5-20 wt.%.

Description

[0101] 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:

[0102] FIG. 1 shows a stack of packaging units;

[0103] FIG. 2 shows a schematic overview of the method according to the invention;

[0104] FIGS. 3A and 3B show a packaging unit according to the present invention

[0105] FIGS. 3C and 3D show an alternative packaging unit according to the invention;

[0106] FIG. 3E shows a detail of the laminated multi-layer;

[0107] FIG. 4 shows a plate as food receiving product according to the invention;

[0108] FIGS. 5A and 5B shows a packaging unit according to the invention comprising PBS and/or another biodegradable aliphatic polyester;

[0109] FIGS. 6A and 6B shows an alternative food packaging product and a meat dish according to the invention;

[0110] FIG. 7 shows a bottle divider according to the present invention;

[0111] FIGS. 8A and 8B show further packaging units according to the invention;

[0112] FIGS. 9A and 9B show a packaging unit for eggs according to the invention;

[0113] FIG. 10 shows experimental results with conventional packaging units and packaging units according to the present invention.

[0114] Stack 1 (FIG. 1) comprises a number of stacked egg packaging units 3. To enable a stable stack packaging units 3 must be able to carry the upper units 3.

[0115] To produce units 3 with sufficient strength, method 1002 (FIG. 2) starts by providing the required raw materials 1004, such as hard wood fiber material and/or soft wood fiber material and/or non-wood fiber material. The raw material 1004 is prepared in step 1006 to achieve raw moulded pulp material 1008. Optionally, one or more pretreatments steps are performed. Pretreatment may involve one or more of mixing, kneeding, shreddering and/or other suitable pretreatments. Raw moulded pulp material 1008 is extruded in extrusion step 1010. In the illustrated embodiment during extrusion step 1010 additional materials are added, such as fixative(s) 1012 and pigment(s) 1014. Optionally, other additives are added during extrusion step 1010 and/or during preparation step 1006. After extrusion 1010, moulded pulp material 1016 is provided to the manufacturing step 1018 to manufacture moulded packaging units 1020 that are dried in drying step 1022. Packaging units 1024 are stored/transported/displayed in handling step 1026. Used packaging units 1028 are degraded/composted/recycled in final or recycling step 1030.

[0116] Next, some examples of packaging units that are manufactured from moulded pulp using method 1002 are shown.

[0117] Packaging unit 2 (FIG. 3A) relates to a food receiving container having bottom part 4 and side walls 6 defining opening 8. In the illustrated embodiment, on the inside of container 2 there is provided laminated multi-layer 10 comprising a compostable vinyl alcohol polymer. In the illustrated embodiment layer 10 comprises print 12. Preferably, in the illustrated embodiment the print is provided on the back side of laminated multi-layer 10.

[0118] In the illustrated embodiment container 2 is provided with peelable top seal film 13a (FIG. 3A). Edge 13b of film 13a is shown as peeled from edge 13c of container 2. In this embodiment top seal film 13a is shown as transparent film. It will be understood that film 13a can also be provided as non-transparent, or alternatively as semi-transparent and/or partly transparent. Alternatively container 2 can also be provided without top seal film 13a.

[0119] In the illustrated embodiment, laminated multi-layer 10 (FIG. 3B) comprises a food oriented side 14 and a packaging side 16. In the illustrated embodiment parts 18 can be removed or cut from sheet or layer 10 to dimension laminated multi-layer 10 according to the specifications and enable providing layer 10 into the inside of container 2. This enables positioning laminated multi-layer 10 correctly relative to corners 20. In this illustrated embodiment print 12 is provided in a mirror image on package side 16 of laminated multi-layer 10 to render the render print 12 visible for a user or consumer.

[0120] Packaging unit 22 (FIG. 3C) provides a further embodiment of a food receiving container having bottom part 24 and side walls 26 defining opening 28. Packaging unit 22 has length L, width W and height H. On the inside of container 22 there is provided laminated multi-layer 30, optionally comprising a print. In the illustrated embodiment laminated multi-layer 30 is provided on the inside of packaging unit 22 and extends from bottom part 24 up to contour or edge 32. Contour or edge 32 is provided a small distance from the upper side of edge 34. This distance is preferably in the range of 1 to 12 mm. Edge 34 (FIG. 3D) is provided with width W1 that defines contact surface 36 for connecting to liner or seal 33 that is schematically illustrated. In the illustrated embodiment this liner or seal 33 is connected directly to the moulded pulp material, optionally with an adhesive, in stead of being connected to laminated multi-layer 30. Such adhesive preferably comprises an amount of biodegradable polyester, for example PBS. Width W1 is in the illustrated embodiment in the range of 1 to 15 mm, preferably in the range of 2 to 5 mm.

[0121] Packaging unit 22 (FIG. 3C) comprises first denesting elements 38 and second denesting elements 40. In the illustrated embodiment, optional top seal film 42 is provided.

[0122] Laminated multi-layer 10 (FIG. 3E) comprises first cover layer 10a, first intermediate layer 10b, central functional layer 10c, second intermediate layer 10d, and second cover layer 10e. It will be understood that other layers can be added to multi-layer 10. It will be understood that lamintated multi-layer 10 can be applied to container 2, and also to packaging unit 22 and more specifically the food contact surfaces of bottom part 24 and side walls 26 thereof.

[0123] In another embodiment, plate 50 (FIG. 4) is on the food receiving side provided with laminated multi-layer 52. In the illustrated embodiment bottom or back side 54 of plate 50 is not provided with such laminated multi-layer. Optionally, plate 50 is provided with top seal film 56, for example in case of plate 50 holding a salad or soup. It will be understood that also other food products can be held by plate 50. Multi-layer 52 is preferably similar to multi-layer 10 that was already illustrated.

[0124] Packaging unit 102 (FIG. 5A and B) carries or holds eggs and comprises cover part 104 and bottom part 106. Bottom part 106 is provided with back surface 108, sides 110 and front surface 112, and bottom surface 114. Cover part 104 is provided with back surface 116, side surfaces 118, front surface 120 and top surface 122. In the illustrated embodiment transition 124 is provided between top surface 122 and back and front surfaces 116, 120.

[0125] In the illustrated embodiment, top surface 122 of cover part 104 is provided with groove 126 comprising a number of openings 128. Openings 128 are defined by two adjacent arch-shaped edges 130, 132 having a larger thickness as compared to the average thickness of cover part 104.

[0126] Side surfaces 118 of cover part 104 are provided with denest nocks or denest elements 134. In the illustrated embodiment, bottom part 106 is provided with similar elements 136 mirroring denest elements 134. Hinge 138 connects back surface 116 of cover part 104 with back surface 108 of bottom part 106. Lock 140 comprises nose-shaped lock element 142 that is connected to flap 144 of bottom part 106. Cover part 104 is provided with openings 146 that capture lock elements 142 therewith defining lock 140.

[0127] In the illustrated embodiment, bottom part 106 is provided with a number of product receiving compartments 148, cones 150 and separating walls 152. Cone 150 extends from the bottom of bottom part 106 in an upward direction. Cover part 104 comprises cone support 154. Inner surface 158 of packaging unit 102 may comprise PBS and/or other suitable biopolymer material, optionally as film layer or alternatively blended and/or integrated with the fibers of the moulded pulp material. Packaging unit 102 may also be configured to receive other products, such as tomatoes, kiwis.

[0128] Packaging unit 202 (FIG. 6A) comprises laminated multi-layer 201 that is provided on bottom part 204 and cover part 206. Multi-layer 201 is preferably similar to multi-layer 10 that was already illustrated. Unit 202 is provided with biodegradable aliphatic polyester, such as PBS, and is capable of holding an amount of ice cream. Cover part 206 comprises top seal 208 of a layer or film 210 of biodegradable aliphatic polyester(s), wherein optionally a (paper) label is provided. Optionally, fibers 212 are included in the cover part 206. This improves the possibilities for giving the unit a natural paper feel and/or look. This may also be applied to other type of packaging units. For example, in instant or ready-to-eat meals, such conventional sleeves can be omitted from the packaging units. This enables a more cost-efficient packaging unit with a possible weight reduction.

[0129] Packaging unit 202 has numerous applications, including but not limited to, airplane meals. Such meals are provided to the airplane after (dry) sterilisation and pasteurisation. In combination with the (O.sub.2)-barrier properties of the laminated multi-layer (and top seal film) the shelf-life of the food product is significantly improved. In addition, the O.sub.2-barrier prevents or at least reduces oxidation processes in the food and thereby contributes to the maintenance of food taste.

[0130] Meat dish 250 (FIG. 6B) is provided from an extruded moulded pulp that is preferably provided with a pigment and a fixative. Dish 250 comprises bottom 252 and side wall 254. In the illustrated embodiment bottom 252 comprises a number of protrusions 256. It will be understood that protrusions 256 are optional. Also, the shape of protrusions may be chosen differently. Also optional, laminated multi-layer 251 is provided. Not shown is a seal or top film that covers dish 250.

[0131] As a further example, bottle divider 302 (FIG. 7) is illustrated with optionally laminated multi-layer 301. Multi-layer 301 is preferably similar to multi-layer 10 that was already illustrated. Also, bottle divider 102 may comprise an additional film layer of PBS (and/or appropriate alternative biodegradable aliphatic polyester) and/or may comprise an amount of PBS that is blended into the moulded pulp.

[0132] A further example in accordance with the present invention is cover 402, for example for an ice cup (FIG. 8A) that is provided with laminated multi-layer 401. Another example of a packaging unit according to the invention is sip lid 502 (FIG. 8B) that is provided with laminated multi-layer 501. Multi-layers 401, 501 are preferably similar to multi-layer 10 that was already illustrated. Cover 402 and sip lid 502 comprise an additional film layer of biodegradable aliphatic polyester and/or may comprise an amount of biodegradable aliphatic polyester that is blended into the moulded pulp. This renders cover 402 and sip lid 502 water or liquid repellent and/or improves the heating step to melt or fuse laminated multi-layer 401, 501 on or to cover 402 and/or sip lid 502. It will be understood that such lids 502 can also be applied to other food containers. For example, lids 502 can be applied to containers for milkshakes, for example. Further details and examples of lids 502 are disclosed in WO 2010/064899, including embodiments with specific flanges and notches. Also, sip lids can be applied to so-called ready meal trays (for example for pizza, wraps, fish, meat, lobster, pasta, ...) and act as a (digital) printable and barrier seal, for example.

[0133] It will be understood that other designs for packaging units in accordance with the invention can be envisaged. For example, containers 602, 702 (FIG. 9A and B) illustrate different designs for egg cartons capable of holding eggs P and comprise laminated multi-layer 601, 701. Multi-layers 601, 701 are preferably similar to multi-layer 10 that was already illustrated.

[0134] Other examples of food packaging products may relate to cup carriers, cups, plates and other table ware etc.

[0135] When manufacturing a food packaging unit 2, 3, 50, 102, 202, 252, 302, 402, 502, 602 a moulded pulp material is prepared. Optionally, an amount of biodegradable aliphatic polyester, such as PBS and/or PHBH, is blended or mixed into the moulded pulp material and/or an amount of biodegradable aliphatic polyester, such as PBS and/or PHBH is included in a separate layer that is provided in or on unit 2, 3, 50, 102, 202, 252, 302, 402, 502, 602. Such separate layer may improve the contact with laminated multi-layer 10, 52, 101, 201, 251, 301, 401, 501, 601 optionally comprising a vinyl alcohol polymer, such as HAVOH and/or BVOH. Preferably, laminated multi-layer is co-extruded with the moulded pulp material and deep-drawn. In addition, or as an alternative, the raw unit is moulded. Optionally, the raw unit is dried in the mould applying an in-mould drying process. In such alternative embodiment laminated multi-layer 10, 52, 101, 201, 251, 301, 401, 501, 601 is provided in the mould and a heating step is performed. Optionally, an additional layer of biodegradable aliphatic polyester is provided to improve the contact between the packaging unit and the laminated multi-layer. Finally the product is released from the mould.

[0136] Several post-drawing or post-moulding operations may optionally be performed in relation to unit 2, 3, 50, 102, 202, 252, 302, 402, 502, 602 optionally including, but not limited to, labelling including in-mould labelling, marking including printing and digital printing, testing.

[0137] Experiments have been performed with one or more of the illustrated food packaging units that were manufactured from a moulded pulp that was provided involving an extrusion process.

[0138] In a first test a hardwood-softwood cellulose pulp mixture was used, using e.g. about 60% softwood cellulose pulp (spruce, pine), combined with about 40% hardwood cellulose pulp (like birch), both for the Twin Screw extrusion and the standard pulped and refined pulp. In the experiments a peristaltic pump was used. From the pulp hand sheets were made in both cases, and also 3-dimensional in-mould dried products.

TABLE-US-00001 Results of the hand sheets tests: Tensile index (Nm/g) E modulus (MPa) Taber stiffness (mN) Shopper Riegler (SR) Standard: 20 - 40 400 - 1000 1000- 1200 20 - 40 Extrusion: 20 - 43 400 - 950 1000 - 1250 25 - 45

[0139] Standard involved standard pulping follow by a disc refining process. The applied refining energy was 40-80 kWh/t.

[0140] Extrusion involved so-called twin screw extrusion.

[0141] From these hand sheet mechanical strength and freeness (SR relating to pulp freeness, dewatering) observations it can be concluded that the Twin Screw Extrusion can achieve a similar or slightly better result as when using a standard paper making set up using a pulper and disc refiner. The Twin Screw technology could therefore replace a pulper and refiner. Another observation during the tests was that the fibrillation of the fibers is better, i.e. leaving more open positions on the fibers to bind cationic additives like AKD sizing. Also the average fiber length of the extrusion process leads to a fiber length that is approximately 60% larger as when the same pulp/fibers are used in a conventional pulping and refining process. This may obviate the need for a conventional pulper and refiner combination. These larger fibers enhance the dewatering of a fiber slurry in a paper making process or in a moulded fiber process, both for an in-mould drying molded fiber process, where the paper slurry after the 1.sup.st forming step under vacuum is formed followed by one or more drying steps in a heated mould, and also in a conventional moulded fiber process where the paper slurry after the 1.sup.st forming step under vacuum is formed and then dried in a conventional drying process (like a gas heated and/or electrical heated drying oven).

[0142] Results of an in-mould drying process of a 3-dimensional packaging unit, using moulded pulp disclosed/refined in a Twin screw extrusion process show that the dryness of the pulp in the first forming step is 25 - 35%, where at the same machine with conventional refined pulp a dryness is achieved between 20 - 25% at low temperatures (ambient temperature). At higher process water temperatures the difference in dryness is slightly higher (2-3%), but remains in the same band width between the two refining technologies. This higher dryness leads to a faster machine speed to produce products. Also it saves energy to dry the products. Another observation of in-mould dried products that were refined in a Twin Screw Extruder system compared to conventional pulped and refined pulp is that the strength and stiffness of the in-mould dried products made out of the pulp is 40 - 70% better. For example, the Taber Stiffness was in the range of 40 -80% higher and also the compression strength of a 3D molded product is 40 - 80% higher.

[0143] The experiment showed that this way of refining a hardwood-softwood mixture in an extrusion process is therefore also enabling IMD moulded pulp product producers to make lighter weight products with remaining the same stiffness and strength properties leading also to lower drying energy levels, a better carbon footprint for the products. Depending on the application of the moulded pulp product in the market (like a meat tray used in a skin packaging where the tray needs to be very strong to avoid collapsing or warpage of the tray) this technology can also lead to stronger products, stiffer products.

[0144] Another observation from the experiments is that due to a different way of refining the fibers, leading to different fibrillation and creating more open spaces on the fibers, anionic charged, to bind cationic charged molecules like an AKD sizing or other cationic charged molecules like dyes or fixatives to bind pigments. To illustrate that effect: Twin screw refined pulp adding 2% AKD sizing, as received from suppliers (with ca 15% effective alkyl ketene dimer) lead to a Cobb (60 sec) of 10-20 g/m2, where the same pulp refined in the conventional way leads with same AKD sizing to a Cobb (60 sec) of 20-45 g/m.sup.2. It was shown that pigments could bind more easy to the fibers in the extrusion process. Furthermore, it was established that the process water in the extrusion process was less polluted with pigments as compared to conventionally adding pigments.

[0145] Other tests were performed to show the dual ovenable (oven and microwave) performance of the packaging unit according to the invention. In the experiments the laminated product was heated to a temperature of about 190° C. for about 30 minutes. Results show that the film layer remains intact and does not melt. No leakage was detected. Furthermore, the strength and stability of the packaging unit were not significantly affected. As a further effect, the packaging unit was more stable in view of twisting when removing the packaging unit from the oven as is often the case with conventional packaging units. Furthermore, the packaging unit of the invention showed a limited temperature increase to about 50-70° C., while the conventional units reached a temperature of about 90-100° C. under similar conditions. Other experiments with a (food) tray shows an even improved heat resistance when heating the tray to a temperature of 180-200° C., and in addition shows (an improved) oil, acid and moisture resistance/repellence.

[0146] Other tests were performed to show the performance of the packaging unit according to the invention by heating the packaging unit in an oven and/or microwave. In the experiments the laminated product, comprising a laminated layer with a total thickness of about 40 .Math.m, was heated to a temperature of about 180° C. for about 35 minutes. Results show that the film layer remains intact and does not melt. No leakage was detected. Furthermore, the strength and stability of the packaging unit were not significantly affected. As a further effect, the packaging unit was more stable in view of twisting when removing the packaging unit from the oven as is often the case with conventional packaging units. Leaking of the film layer was tested by using food simulantia such as 95% ethanol, modified polyphenylene oxide (MPPO), 2,2,4-trimethylpentane, and the like. Thus, this test showed a safe use of the laminate product as packaging, for example food packaging.

[0147] 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. It is noted that this invention is not limited for cellulose fibers and not limited for smooth molded fiber processes but works for any biomass/fiber/ alternative fiber material, also in the rough molded fiber process. Also, this invention is not limited to 3D moulded fiber production and can also be applied to the flat paper production in paper mills facing similar challenges with coloured water treatment.