Beverage capsule made from molded cellulose with improved oxygen and moisture barrier

Abstract

The present invention relates to an improved packaging article (1) comprising a body (2) made of a rigid or semi-rigid molded cellulose slurry, said article further comprising a multilayer film liner (3) attached to the inner surface of the cellulose slurry body (2), said liner comprising, from inside to outside: a biodegradable outermost organic adhesive layer (7), the biodegradable outermost organic bonding layer is used for attaching the inner liner to the molded cellulose slurry; an organic intermediate barrier layer (8) comprising a modified alcohol-based polymer (BVOH); and an innermost biodegradable organic structural layer (9).

Description

Technical Field

[0001] The present invention relates to a capsule for beverage preparation, which capsule is circulatable in a paper recycling stream and comprises an outer body made of compressed cellulose pulp coupled with a gas and moisture barrier lining tightly adhered to said pulp body. Background Art

[0002] Packaged items have traditionally been made of various materials such as glass and metal, but in recent decades they have been made primarily of plastic polymers that are cheap, easy to process and lightweight. Recently, however, due to increased environmental awareness, technological advances have been needed to replace plastics with materials that can provide the same level of food safety and convenience while being more recyclable or biodegradable and therefore more environmentally friendly.

[0003] Such packaging items may be, for example, capsules and sachets for beverage preparation in beverage preparation machines, which are well known. Such packaging items may also be so-called "secondary packaging", such as a sachet wrapped around a primary packaging item.

[0004] Capsules are a convenient and clean method of consuming beverages. In the following description, the general term "capsule" will be used and covers a disposable package for preparing a beverage for human consumption by insertion into a beverage preparation machine adapted to inject a fluid (in principle hot water) into the package to mix with the ingredients contained in the package. Examples of such beverage packages are not limited to rigid capsules, but also include rigid, semi-rigid or flexible sachets, powder packets, various types of boxes, and even bag-type containers.

[0005] Typically, such capsules are made of plastics such as polyolefins or biodegradable plastics which are usually injected or thermoformed to obtain a cup filled with the ingredients and then closed with a septum to close the capsule in an airtight and moisture-proof manner.

[0006] During beverage preparation, the capsule is inserted into a brewing chamber of a beverage preparation machine. The machine comprises water injection means, such as a needle or a set of blades designed to pierce the thickness of the capsule body and inject water therein under pressure. The water is mixed with the ingredients that produce the beverage. When the water pressure increases and reaches a certain level, the closing diaphragm deflects outwards and pierces onto the piercing means of the beverage machine. When the diaphragm is pierced, the beverage can flow out of the capsule towards a cup.

[0007] As mentioned above, in recent times there has been a growing awareness of the impact of packaging plastics on the environment and a need for new packaging solutions which are biodegradable or recyclable after use and which in particular enable the used packaging to be composted or recycled in a recycling stream suitable for paper or cartons ("paper recycling stream").

[0008] Thus, among other packaging articles, beverage preparation capsules have recently been developed that are made of cellulose fiber slurry (or "cellulose pulp" or "pulp") that is molded to form a rigid or semi-rigid capsule cup-shaped body that defines a compartment for containing beverage precursor ingredients such as roast and ground coffee. The cup-shaped body is closed by attaching (e.g., by sealing) a wall such as a diaphragm or membrane thereto.

[0009] In order to guarantee the freshness of the beverage precursor ingredients during the life of the capsule, in particular during storage until use, it is necessary to incorporate oxygen and moisture barrier materials into the cellulose pulp (as well as the closing membrane). The barrier material usually takes the form of a so-called "barrier liner", which is a film with five to ten individual layers attached to each other. The multilayer liner film is adhered to the inner surface of the pulp body (i.e. the surface facing the ingredients). Adhering the liner to the pulp is done by thermoforming the two in a mold. Not all layers in the barrier liner themselves bring barrier properties: some of them act as adhesion promoters between other barrier layers of the liner and the structural layers. Such adhesion-promoting layers are so-called "tipping layers".

[0010] Furthermore, it was found that certain properties of the polymer used to make the barrier membrane must be carefully selected so that during piercing of the capsule by a water injection device, the liner does not stretch without piercing, or delaminate from the molded slurry material.

[0011] Generally, beverage preparation using slurry-based capsules with a barrier liner film as described above is a very promising way to reduce the environmental footprint of packaging.

[0012] However, due to the current trend to develop packaging made of biodegradable materials, many of these structures fail to meet the biodegradability requirements under home composting conditions. This is due to the fact that the structural materials are compounded and / or only partially biodegradable. This is especially true for the polymer materials used to make the barrier liner film.

[0013] Furthermore, current solutions for so-called "tie layers" in barrier liners are non-biodegradable (or have only limited biodegradability) above a certain thickness limit, while tie layers in barrier liners used for capsules have a thickness above this limit and are therefore not suitably biodegradable.

[0014] Additionally, the complexity of integrating more than five layers of materials in a barrier liner film, with significantly different thermal properties (melting point, viscosity, melt flow index or MFI), is challenging from a manufacturing standpoint.

[0015] In the case of beverage capsules, the same technical challenges described above are presented to other types of packaging articles, such as secondary packaging made of molded slurry and comprising a barrier liner.

[0016] It is therefore an object of the present invention to provide a technical solution to the above challenges in packaging articles in general, in particular beverage capsules made of molded slurry and comprising a barrier liner, and in particular by providing a fully biodegradable (home compostable) packaging article that eliminates the above disadvantages. Summary of the invention

[0017] The present invention achieves the above-mentioned objects by a packaging article comprising a body made of rigid or semi-rigid molded cellulose pulp, characterized in that the article also comprises a multilayer film liner attached to the inner surface of the cellulose pulp body, the liner comprising from the outside to the inside (the "inside" is the part of the liner in contact with the product, and the "outside" is the part of the liner in contact with the cellulose body of the packaging article):

[0018] (i) an outermost organic adhesive layer for attaching the liner to the molded cellulose pulp, the adhesive layer comprising a biodegradable polymer selected from the following list:

[0019] polybutylene succinate (PBSA / bioPBS), polybutylene adipate terephthalate (PBAT), starch, cellulose derivatives, polylactic acid (PLA), polyhydroxyalkanoate (PHA) or a combination thereof, the outermost layer having a thickness between 10 μm and 100 μm, an elongation at break between 10% and 800%, a melt flow rate (MFR) between 2 and 4 when measured at 150°C under a pressure of 2.16 kg for 10 minutes, and the layer also having a melting point temperature below 80°C,

[0020] (ii) an organic intermediate barrier layer comprising butene glycol vinyl alcohol copolymer grafted with maleic anhydride (BVOH), polyglycolic acid grafted with maleic anhydride (PGA), or a mixture thereof, and having a melting point temperature between 180° C. and 230° C. and a thickness between 1 μm and 20 μm,

[0021] (iii) an innermost organic structural layer, which comprises a biodegradable polymer selected from the following list: polybutylene succinate (PBSA), polybutylene adipate terephthalate (PBAT), starch, cellulose derivatives, polylactic acid (PLA), polyhydroxyalkanoate (PHA) or a combination thereof, said layer having a thickness between 10 μm and 100 μm, an elongation at break between 10% and 1000%, a melt flow rate (MFR) between 4 and 10 when measured at 190°C under a pressure of 2.16 kg for 10 minutes, and said structural layer also has a melting point temperature between 110°C and 180°C.

[0022] The capsule according to the invention makes it possible to remove the adhesive layer from the barrier liner structure, thus making the entire material biodegradable under home composting conditions. The resulting barrier liner comprises only three layers, which is also advantageous in terms of manufacturing complexity. The inventors surprisingly found that by modifying the BVOH barrier layer and grafting it with maleic anhydride groups, its compatibility with the PBS-based resin (which is the main component of the adjacent outer layer and the adhesive layer) is greatly improved, making it possible to reduce the barrier liner complexity to only three layers. Due to this improved chemical (and therefore mechanical) compatibility, it is no longer necessary to use an intermediate adhesive layer.

[0023] Additionally and interestingly, polymers suitable for use in the present invention are biodegradable polymers, preferably home compostable polymers. Home compostability is now well defined at a national level and is largely based on the international standard EN 13432; therefore, in this specification, they do not need to be defined further in depth. Materials or products that meet these standards can be identified by a conformity mark stating their home compostability. Some examples of home compostability certifications at a national level include, but are not limited to, the following. Certification Bodies AUSTRIA BELGIUM offers such a home compostability certification scheme and DIN CERTCO offers home compostability certification according to the Australian standard AS 5810. Italy has a national standard UNI 11183:2006 for composting at ambient temperature. In November 2015, the French standard "NFT51-800 Plastics - Specification for plastics suitable for home composting" was introduced. This standard is covered by the DIN CERTCO scheme.

[0024] According to the principles of the present invention, a multi-layer liner is provided with a barrier layer (to oxygen and / or moisture) as an intermediate layer. The physical properties of the innermost and outermost layers are carefully selected:

[0025] - the outermost layer in contact with the slurry has a low melting point temperature (below 80°C), which brings about high cohesion with the slurry; this is due to the fact that during the thermoforming of the liner into the slurry body, when the temperature is increased, the polymer constituting the outermost layer flows rapidly with low viscosity between the slurry fibers of the body and saturates the slurry; then, when the temperature is lowered after the thermoforming step, the polymer layer of the liner hardens and the polymer is completely tangled between the slurry fibers, making it impossible to peel the liner from the slurry body, and in addition

[0026] - The innermost layer in contact with the beverage ingredients has a high melting point (above 110°C). The higher melting point than the outermost layer ensures that during the thermoforming of the liner with slurry, the outermost layer, due to its melting point far below the usual thermoforming temperature, melts very quickly and is in a preferably liquid state, so that it flows between the cellulose fibers of the slurry and so that when it cools after thermoforming, the material constituting the outermost layer intermingles with the slurry cellulose fibers and adheres to them. At the same time, the innermost layer, due to its higher melting point (above the usual thermoforming temperature), does not melt during the thermoforming process step, so that when the thermoforming of the liner into slurry is completed and the thermoforming mold is opened, the innermost layer is easily separated from the thermoformed plug.

[0027] The so-called "liner" refers to a single-layer or multi-layer film obtained by extrusion-blow molding, or extrusion-lamination, or cast-extrusion.

[0028] The single or multilayer liner applied to the slurry substrate is different from the single or multilayer obtained by coating the slurry substrate. It is challenging to apply a barrier layer to a molded slurry substrate because the surface of the molded slurry is rough and uneven. Therefore, before the barrier layer can be applied, a high thickness of the formulation surface coating must be applied to smooth the slurry surface. If the surface is not smooth, there is a risk that the barrier layer may be applied in an uneven manner, so that some areas are not adequately coated, thereby compromising the barrier properties of the entire article. The application of the liner does not cause such problems because all layers are pre-formed in a uniform manner and the barrier layer is uniform over the entire surface of the liner before it is applied to the molded slurry substrate. Therefore, the barrier layer quality is ensured over the entire surface of the resulting article and less polymer material is required than a coating.

[0029] Furthermore, coatings are usually applied on flat sheets of substrate material. However, capsules have a three-dimensional geometry which makes it difficult, if not impossible, to apply thin layers of molten polymer. Furthermore, the challenges associated with coatings on fiber-based materials are really related to the surface quality (rough or smooth) which is related to the presence of loose fibers in the coating / fiber interface. These loose fibers will lead to pinholes through which water vapor and oxygen can migrate. In the case of thermoformed lamination, this problem is avoided.

[0030] In a first embodiment of the invention, the packaging article is a secondary packaging for enclosing a primary packaging, said secondary packaging preferably being selected from the following list, for example: a pouch, a gusset wrap, a tube, a bag, a box, a brick, a container or a combination thereof.

[0031] In a second embodiment of the invention, the packaged article is a capsule for beverage preparation, comprising a cup-shaped body and at least one closed membrane attached to the body, the body and the at least one membrane defining a closed ingredient compartment, the capsule being adapted to be pierced by a water injection device of a beverage preparation machine for injecting water under pressure into the compartment for preparing a beverage therein.

[0032] Preferably, the cup-shaped body of the capsule comprises a peripheral rim to which the closing membrane is attached.

[0033] Furthermore, the closing membrane can advantageously be made of extrusion coated paper, fiber spun coated paper or a polymer film comprising a compatible polymer material.

[0034] The ingredient inside the compartment of the beverage capsule according to the second embodiment of the invention is preferably roast and ground coffee.

[0035] Regardless of the embodiment of the invention, the outermost layer, the innermost layer and the barrier layer are preferably coextruded layers.

[0036] Additionally, the innermost layer of polymer may be an annealed polymer which provides increased mechanical and structural properties to the liner. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Additional features and advantages of the present invention are described in, and will be apparent from, the following description of presently preferred embodiments given with reference to the accompanying drawings, in which:

[0038] Figure 1 is a schematic perspective view of a partially cut capsule according to a first embodiment of the present invention;

[0039] Figure 2 is a schematic cross-sectional view of a multi-layer liner according to the present invention;

[0040] Figure 3 , Figure 4 , Figure 5A , Figure 5B , Figure 5C is a schematic diagram of the different steps of attaching a barrier liner to a molded slurry cup-shaped body according to the present invention. DETAILED DESCRIPTION

[0041] like Figure 1As shown, the first embodiment of the present invention relates to a packaging article for preparing a beverage capsule 1. The beverage capsule 1 comprises a cup-shaped capsule body 2, the inner surface of which is covered with an oxygen and barrier liner 3. Figure 1 , the liner 3 is also shown on the left in an enlarged view showing its three constituent layers. The capsule body 2 also comprises a peripheral rim 4 around an opening, which is closed by a closing membrane 5 sealed to the rim 4. The capsule body closed by the membrane 5 defines a compartment 6 for the roasted and ground coffee ingredient contained therein.

[0042] As shown in the enlarged partial view, Figure 1 On the right-hand side, the cup-shaped capsule body 2 is made of molded cellulose pulp. Figure 1 The enlarged partial view shows the shingled arrangement of cellulose fibers.

[0043] The barrier liner 3 is a multilayer film, an embodiment of which is shown in Figure 2 In this embodiment, the liner comprises the following three layers attached to each other. The layers are described from the outermost layer of the barrier liner 3 (i.e., the layer adjacent to the body of the cellulose molded pulp capsule) toward the innermost layer, which is the layer in contact with the product or ingredient contained in the capsule.

[0044] First, the inner liner 3 includes an outermost adhesive organic polymer layer 7 made of a formulation based on polybutylene adipate terephthalate (PBAT). This outermost layer has a thickness of 17 μm, an elongation at break of 600%, and serves as an adhesive for the slurry. It is also characterized by a melt flow rate (MFR) of 3 (measured at 150° C. under a pressure of 2.16 kg for 10 minutes) and a melting point temperature of 75° C.

[0045] The core layer located in the middle of the multilayer liner structure is a barrier layer 8 made of butene glycol vinyl alcohol copolymer (BVOH), which is modified by grafting maleic anhydride groups onto the BVOH molecules and has a melting point temperature of 200° C. and a thickness of 8 μm. The barrier layer provides a barrier to prevent the transfer of oxygen and moisture between the external atmosphere and the capsule compartment.

[0046] at last, Figure 2 The liner in the embodiment depicted in the embodiment comprises an innermost organic polymer structural layer 9 made of a formulation based on polybutylene adipate terephthalate (PBAT). The innermost layer has a thickness of 17 μm and an elongation at break of 177%. It is also characterized by a melt flow rate (MFR) of 6 measured at 190°C under a pressure of 2.16 kg for 10 minutes. The layer has a melting point temperature of 115°C.

[0047] Typically, the adhesive layer 7 and the structural layer 9 are biopolymers selected from the following list: PBSA, PBAT, starch, cellulose derivatives, PLA, PHA and combinations thereof. The outermost adhesive layer 7 has a lower melting point temperature of at least 10°C, preferably 20°C, than the structural layer.

[0048] As described above, butene glycol vinyl alcohol copolymer (BVOH) having improved affinity for biopolyester is used in the middle barrier organic layer 8. The improved affinity of the BVOH used therein with the biopolyester is due to the fact that the BVOH polymer molecule is grafted with maleic anhydride groups, thereby increasing its compatibility with the PBS-based resin, which is the main component of the adjacent innermost and outermost layers.

[0049] The BVOH barrier layer 8 is coextruded into a three-layer film together with the adhesive layer 7 and the structural layer 9. This modified BVOH allows for sufficient adhesion between the two outer layers to allow the material to be extruded, handled and thermoformed.

[0050] Alternatively, the layer may also be a modified (ie, maleic anhydride grafted) polyglycolic acid (PGA) polymer instead of BVOH.

[0051] As described below, the thickness of each layer in the liner 3 according to the present invention varies from layer to layer.

[0052] The adhesive layer 7 has a thickness between 10 μm and 100 μm, preferably between 10 μm and 50 μm, and in a particular example it has a thickness of 22 μm.

[0053] The barrier layer 8 has a thickness between 1 μm and 20 μm, and in a specific example it has a thickness of 8 μm.

[0054] The structural layer 9 has a thickness between 10 μm and 100 μm, preferably between 10 μm and 50 μm, and in a particular example it has a thickness of 40 μm.

[0055] The lining structure may be symmetrical or asymmetrical in thickness, which means that the adhesive layer 7 and the structural layer 9 may have similar or different thicknesses.

[0056] Typical barrier values ​​can be 0.05cc / m 2 / day / atmosphere to 0.8cc / m 2 / day / atmosphere pressure changes, preferably less than 0.1cc / m 2 / day / atmosphere.

[0057] The advantage of the asymmetric structure is that the warping and folding of the liner is reduced. This simplifies post-processing such as thermoforming and film handling.

[0058] The capsule 1 according to the first embodiment of the present invention is manufactured through the following steps in order.

[0059] like Figure 3 As shown in the figure, a capsule cup 10 is first molded from a dry or wet (preferably wet) slurry mixture. Molding cellulose slurry is already known in the art and will not be described in more detail in this specification. The slurry cup 10 has an opening 11 into which roasted and ground coffee ingredients can be filled (not shown).

[0060] Then, if Figure 4 and Figure 5A As depicted, the barrier liner film 3 is provided as a flat sheet 12 and placed over the opening 11 of the slurry cup 10 when the slurry cup 10 is placed into a mold 13 and heated.

[0061] Then, if Figure 5B As shown, a plunger 14 is applied to the surface of the flat sheet 12, which is moved toward the interior of the cup 10 so that the barrier liner is pushed into the vicinity of the interior of the cup until the liner is fully attached to the slurry cup surface, as shown. Figure 5C The technology of attaching the barrier liner sheet 12 to the surface of the slurry cup 10 is mainly based on plug-assisted thermoforming, which is already known in the art and will not be described in detail in this specification.

[0062] Once the process of attaching the barrier liner 12 to the inner surface of the slurry cup 10 is completed, the peripheral edge 4 is trimmed (ie, cut to the correct diameter) so that a surface such as Figure 1 An empty slurry capsule with barrier properties is shown, comprising an opening through which coffee powder is filled. The filled capsule is then closed by sealing a septum 5 to the rim 4 of the capsule.

[0063] Typical temperatures for thermoforming the liner into the molded slurry bladder body range between 110° C. and 190° C. for lower and upper heating sources. The plug profile must be properly adapted to the bladder profile to ensure uniform liner material distribution and deformation.

[0064] The final thermoformed capsule has an evenly distributed liner that exhibits good adhesion to the molded slurry surface. Typical barrier values ​​for the capsule and liner structure vary between 0.001 cc / package / day / atmosphere and 0.01 cc / package / day / atmosphere, preferably less than 0.009 cc / package / day / atmosphere, and more preferably less than 0.0033 cc / package / day / atmosphere.

[0065] The features of the invention described above with respect to beverage capsules also apply to another type of embodiment of the invention in which the packaging article is not a beverage capsule but a secondary packaging such as a molded slurry carton for containing a beverage, or a wrap-around pouch for containing a product such as a powdered food. Of course, in each individual case, known manufacturing techniques may be employed to assemble the barrier liner to the molded slurry component of the capsule.

[0066] It should be understood that various changes and modifications made to the presently preferred embodiments described herein will be apparent to those skilled in the art. These changes and modifications may be made without departing from the spirit and scope of the present invention and without diminishing the attendant advantages. Therefore, such changes and modifications are intended to be covered by the appended claims.

Claims

1. A packaging article (1) comprising a body (2) made of rigid or semi-rigid molded cellulose pulp, Features The article (1) further comprises a multilayer film liner (3) attached to the inner surface of the body of cellulose pulp (2), the liner comprising from the outside to the inside: (i) an outermost organic adhesive layer (7) for attaching the liner to the molded cellulose pulp, the adhesive layer comprising a biodegradable polymer selected from the following list: polybutylene succinate (PBSA / bioPBS), polybutylene adipate terephthalate (PBAT), starch, cellulose derivatives, polylactic acid (PLA), polyhydroxyalkanoate (PHA) or a combination thereof, the outermost layer having a thickness between 10 μm and 100 μm, an elongation at break between 10% and 800%, a melt flow rate (MFR) between 2 and 4 when measured at 150°C under a pressure of 2.16 kg for 10 minutes, and the outermost layer having a melting point temperature below 80°C, (ii) an organic intermediate barrier layer (8), which comprises butene glycol vinyl alcohol copolymer grafted with maleic anhydride (BVOH), polyglycolic acid grafted with maleic anhydride (PGA) or a mixture thereof, and has a melting point temperature between 180° C. and 230° C. and a thickness between 1 μm and 20 μm, (iii) an innermost organic structural layer (9), said innermost organic structural layer comprising a biodegradable polymer selected from the following list: polybutylene succinate (PBSA), polybutylene adipate terephthalate (PBAT), starch, cellulose derivatives, polylactic acid (PLA), polyhydroxyalkanoate (PHA) or a combination thereof, said layer having a thickness between 10 μm and 100 μm, an elongation at break between 10% and 1000%, a melt flow rate (MFR) between 4 and 10 when measured at 190°C under a pressure of 2.16 kg for 10 minutes, and said innermost layer also having a melting point temperature between 110°C and 180°C.

2. The packaging article (1) according to claim 1, which is a secondary packaging for enclosing a primary packaging, the secondary packaging preferably being selected from the following list: a pouch, a gusset wrap, a tube, a bag, a box, a brick, a container or a combination thereof.

3. The packaging article (1) according to claim 1, which is a capsule (1) for beverage preparation, the capsule comprising a cup-shaped body (2) and at least one closed diaphragm (5) attached to the body (2), the body (2) and the at least one diaphragm (5) defining a closed ingredient compartment (6), the capsule being adapted to be pierced by a water injection device of a beverage preparation machine for injecting water under pressure into the compartment to prepare a beverage therein.

4. The packaging article (1) according to claim 3, wherein the cup-shaped body (2) comprises a peripheral edge (4) to which the closing membrane (5) is attached.

5. The packaging article (1) according to any one of the preceding claims 3 or 4, wherein the closing membrane (5) is made of extrusion coated paper, fiber spun coated paper or a polymer film comprising a compatible polymer material.

6. The packaging article (1) according to any one of the preceding claims 3 to 5, wherein the ingredient in the compartment (6) is roast and ground coffee.

7. The packaging article (1) according to any one of the preceding claims 1 to 6, wherein at least the outermost layer (7), the innermost layer (9) and the barrier layer (8) are coextruded layers.

8. A packaging article (1) according to any one of the preceding claims, wherein the polymer of the innermost layer (9) is an annealed polymer.

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