Moulded pulp articles with improved barrier properties

Abstract

The present invention relates to a moulded pulp article comprising, from outermost layer to innermost layer, a shaped pulp; a polymer interlayer; and an inorganic barrier layer selected within the list of: metals, metalloids, oxides thereof, or a combination thereof, as well as to methods of producing such moulded pulp articles, uses for such moulded pulp articles, and packaged edible products comprising such moulded pulp articles.

Description

[0001] MOULDED PULP ARTICLES WITH IMPROVED BARRIER PROPERTIES

[0002] Field of the invention

[0003] The present invention relates to moulded pulp articles with improved barrier properties and methods for their production.

[0004] Background of the invention

[0005] Moulded pulp is a material that is used with increasing frequency for packaging, particularly of foodstuffs. A key benefit of these materials is that they are easily recycled and biodegrade, often being home compostable. Existing technologies of moulded pulp allow the production of rigid containers such as paper cans, paper bottles or capsules for beverages through wet or drying processing of cellulose fibres. Being made of cellulosic fibres, it is usually necessary to coat or laminate the moulded pulp in order to add sealing and barrier properties (e.g. to prevent ingress of oxygen, moisture, and oils or grease).

[0006] The provision of moulded pulp with effective barriers to deleterious substances (such as oxygen, water vapour, and / or oils and greases) remains a challenge and significant additional processing is required to provide a suitable barrier. In particular, the provision of effective barriers that do not interfere with the recyclable and biodegradable nature of the mould pulp.

[0007] It is an object of the present invention to solve one or more of the foregoing problems.

[0008] Summary of the invention

[0009] A first aspect of the present invention relates to a moulded pulp article comprising, from outermost layer to innermost layer: a shaped pulp; a polymer interlayer; and an inorganic barrier layer selected within the list of: metals, metalloids, oxides thereof, or a combination thereof.

[0010] The polymer interlayer may comprise a biodegradable polymer, optionally a polymer selected from polylactic acid (PLA), polyhydroxyalkanoates (PHA), polycaprolactone (PCL) polyglycolic acid (PGA), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene adipate terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch, cellulose, carboxymethyl cellulose, hydroxypropylmethyl cellulose), proteins (such as casein, zein, soy protein, silk), PVOH, EVOH, PGA, BVOH, or mixtures thereof.

[0011] The inorganic barrier layer may be selected from aluminium, aluminium oxide (AIOX), silicon oxide (SiOx), or combinations thereof.

[0012] The moulded pulp article may further comprise an organic barrier layer. The organic barrier layer may comprise a biodegradable polymer, optionally a polymer selected from PVOH, EVOH, PGA, BVOH, or mixtures thereof.

[0013] The moulded pulp article may further comprise a contact layer. The contact layer may comprise a polymer, optionally wherein the water polymer is a biodegradable polymer, optionally the biodegradable polymer being selected from polylactic acid (PLA), polyhydroxyalkanoates (PHA), polycaprolactone (PCL) polyglycolic acid (PGA), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene adipate terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch, cellulose, carboxymethyl cellulose, hydroxypropylmethyl cellulose), proteins (such as casein, zein, soy protein, silk) and combinations thereof.

[0014] A second aspect of the present invention provides a method of producing a moulded pulp article, the method comprising: a) providing a pulp; b) shaping the pulp; c) providing a polymer interlayer over the pulp; and d) providing an inorganic barrier layer over the polymer interlayer. The step of shaping the pulp may occur prior to the deposition of any other layer. Alternatively, the step of shaping the pulp occurs after deposition of one or more of the other layers.

[0015] The polymer interlayer may compruse a biodegradable polymer, optionally a polymer selected from polylactic acid (PLA), polyhydroxyalkanoates (PHA), polycaprolactone (PCL) polyglycolic acid (PGA), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene adipate terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch, cellulose, carboxymethyl cellulose, hydroxypropylmethyl cellulose), proteins (such as casein, zein, soy protein, silk), PVOH, EVOH, PGA, BVOH, or mixtures thereof.

[0016] The inorganic barrier layer may be selected from aluminium, aluminium oxide (AIOX), silicon oxide (SiOx), or combinations thereof.

[0017] The method may further comprise the step of providing an organic barrier layer over the inorganic barrier layer. The organic barrier layer may comprise a biodegradable polymer, optionally a polymer selected from PVOH, EVOH, PGA, BVOH, or mixtures thereof.

[0018] The method may further comprise the step of providing a contact layer over the inorganic barrier layer. The contact layer comprises a polymer, optionally wherein the polymer is a biodegradable polymer, optionally the biodegradable polymer being selected from polylactic acid (PLA), polyhydroxyalkanoates (PHA), polycaprolactone (PCL) polyglycolic acid (PGA), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene adipate terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch, cellulose, carboxymethyl cellulose, hydroxypropylmethyl cellulose), proteins (such as casein, zein, soy protein, silk) and combinations thereof .

[0019] A third aspect of the present invention relates to the use of a moulded pulp article according to the first aspect of the present invetnion for packing an edible product for human or animal consumption.

[0020] A fourth aspect of the present invention relates to a packaged edible product, comprising a moulded pulp article according to the first aspect of the present invention, at least partially filled with an edible product for human or animal consumption. As used in this specification, the words “comprises”, “comprising”, and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean “including, but not limited to”.

[0021] Brief description of the drawings

[0022] Additional features and advantages of the present invention are described in, and will be apparent from, the description of the presently preferred embodiments which are set out below with reference to the drawings in which:

[0023] Figure 1 shows a schematic cross section of a moulded pulp article (1) according to the present invention. The moulded pulp article (1) includes a pulp (2), a polymer interlayer (3) and an inorganic barrier layer (4);

[0024] Figure 2 shows a schematic cross section of a moulded pulp article (1) according to the present invention. The moulded pulp article (1) includes a pulp (2), a polymer interlayer (3), an inorganic barrier layer (4), an organic barrier layer (5), and a contact layer (6).

[0025] Detailed description of the invention

[0026] By “dispersion coating”, it is meant a coating technique whereby an aqueous dispersion of fine polymer particles or polymer solution is applied to the surface of paper or board as such, in order to form a solid, non-porous film after drying. Dispersion coating can be performed by gravure, flexo-gravure, rod, blade, slot-die, curtain air knife, roll coating, curtain coating, dip-coating, spray coating, or any other known method of coating paper or moulded three dimensional objects. Dispersion coating can create a much thinner layer than extrusion coating lamination and / or adhesive lamination, since the polymer is mixed in an aqueous water solution. This brings advantages in terms of quantity of polymer usage, its barrier performance and recyclability of resulting paper structure. The target of dispersion coating is to achieve a barrier layer against water, water vapour, grease, oil, gas, etc. Another target is to prepare surface of paper material for a vacuum deposition process.

[0027] By “fibre”, it is meant, for example, a cellulosic fibre, which is generally extracted from plants, seeds or trees; such fibres contain not only cellulose molecules, but also hemicellulose as well as lignin. Other examples of fibres include other synthetic fibres (such as viscose, polyester, or nylon) or natural fibres (such as silk or wool). By “moulded pulp articles”, also known as “moulded fibre articles”, it is meant articles that are formed by the moulding of fibrous materials. The fibrous materials may be obtained by recycling processed fibre sources, such as paper or cardboard, or obtained directly from natural fibre sources, such as wood fibres, sugarcane bagasse, bamboo, and straw. Moulded pulp articles are commonly used for packaging and are widely considered to be sustainable.

[0028] Moulded Pulp Article

[0029] A first aspect of the present invention relates to a moulded pulp article. The moulded pulp article comprises, from outermost layer to innermost layer, a shaped pulp, a polymer interlayer, and an inorganic barrier layer. It has been discovered that the inclusion of the polymer interlayer, placed between the shaped pulp and the inorganic barrier layer, improves the barrier properties of the inorganic barrier layer with respect to limiting the penetration of water vapour and oxygen. Without wishing to be bound by theory, it is believed that the polymer interlayer provides a smooth surface on which the inorganic barrier layer is deposited, resulting in a more effective barrier with fewer defects.

[0030] In embodiments, the moulded pulp article further comprises an organic barrier layer to the inside of the inorganic barrier layer. The organic barrier layer enhances the total barrier properties of the moulded pulp article.

[0031] In embodiments, the moulded pulp article further comprises a contact layer to the inside of the inorganic barrier layer. In embodiments further comprising an organic barrier layer, the contact layer is to the inside of the organic barrier layer. The contact layer serves to separate the organic barrier layer from the contents of the moulded pulp article in use and / or to allow the formation of a heat seal.

[0032] It will be understood that the moulded pulp article may comprise further layers, between the layers described herein, to the exterior of the layers described herein, and / or to the interior of the layers described herein. For example, the moulded pulp article may comprise multiple inorganic barrier layers.

[0033] The inner surface of the pulp may be smooth or have a controlled roughness and / or geometrical features.

[0034] The moulded pulp article includes at a polymer interlayer. The polymer interlayer provides a more suitable surface for the deposition and adhesion of the inorganic barrier layer compared to the preceding shaped pulp. In embodiments, the polymer interlayer also provides a barrier to the passage of gases (such as oxygen) and moisture through the moulded pulp article.

[0035] The polymer interlayer is preferably comprised of biodegradable polymers. The polymer interlayer may comprise a polymer selected from polylactic acid (PLA), polyhydroxyalkanoates (PHA), polycaprolactone (PCL) polyglycolic acid (PGA), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene adipate terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch, cellulose, carboxymethyl cellulose, hydroxypropylmethyl cellulose), proteins (such as casein, zein, soy protein, silk), PVOH, EVOH, PGA, BVOH, or mixtures thereof. Where PVOH, EVOH, PGA, BVOH, or mixtures thereof are selected, the polymer interlayer additionally functions as an organic barrier layer.

[0036] The polymer interlayer may have a thickness of from 1 to 100 pm, optionally from 1 to 50 pm, optionally from 5 to 40 pm, optionally from 10 to 25 pm, such as about 20 pm.

[0037] Inorganic Barrier Layer

[0038] The moulded pulp article includes an inorganic barrier layer. The inorganic barrier layer provides a barrier to the passage of gases (such as oxygen) and moisture through the moulded pulp article.

[0039] The inorganic barrier layer comprises metals, metalloids, oxides thereof, or a combination thereof. The thickness of the inorganic barrier layer is from about 1 to about 100 nm, optionally 10 to 100 nm. Substantially any metal, metalloid, or oxide thereof may be used that provides sufficient barrier properties, robustness, and flexibility in the thickness that it is applied. In addition, the metal, metalloid, or oxide thereof must be food safe.

[0040] In embodiments, the inorganic barrier layer comprises aluminium, aluminium oxide (AIOx), silicon oxide (SiOx), or combinations thereof. Substantially any suitable methodology may be used to deposit the inorganic barrier layer. In embodiments, the inorganic barrier layer is deposited by vacuum deposition or transfer metallization onto the polymer interlayer.

[0041] Organic Barrier Layer

[0042] The moulded pulp article may include an organic barrier layer. The organic barrier layer provides a barrier to the passage of gases (such as oxygen) and moisture through the moulded pulp article.

[0043] The organic barrier layer is preferably comprised of biodegradable polymers. The organic barrier layer may comprise PVOH, EVOH, BVOH, PGA, or mixtures thereof.

[0044] The organic barrier layer may have a thickness of from 0.5 to 20 gsm, optionally from 1 to 10 gsm, such as about 4 gsm.

[0045] Contact Layer

[0046] The moulded pulp article may include a contact layer. The contact layer provides a barrier to the passage of liquid water through the moulded pulp article.

[0047] The contact layer may be comprised of water insoluble polymer. By water insoluble, it is meant that the polymer does not dissolve under standard temperatures and pressures. Preferably, the contact layer is comprised of biodegradable polymers. The contact layer may comprise polylactic acid (PLA), polyhydroxyalkanoates (PHA), polycaprolactone (PCL) polyglycolic acid (PGA), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene adipate terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch, cellulose, carboxymethyl cellulose, hydroxypropylmethyl cellulose), proteins (such as casein, zein, soy protein, silk) and combinations thereof.

[0048] The contact layer may have a thickness of from 5 to 200 pm, optionally from 10 to 150 pm, optionally from 20 to 100 pm, such as about 80 pm.

[0049] In a specific embodiment, the moulded pulp article comprises, from outermost layer to innermost layer: a shaped pulp; a polymer interlayer comprising PVOH, EVOH, PGA, BVOH, or mixtures thereof; an inorganic barrier layer comprising aluminium oxide (AIOX), silicon oxide (SiOx), or combinations thereof; and a contact layer comprising a polyhydroxyalkanoate.

[0050] For example, a moulded pulp article comprises, from outermost layer to innermost layer: a shaped pulp; a polymer interlayer comprising BVOH; an inorganic barrier layer comprising aluminium oxide (AIOX) or silicon oxide (SiOx); and a contact layer comprising a polyhydroxyalkanoate.

[0051] In a further embodiment, a moulded pulp article comprises, from outermost layer to innermost layer: a shaped pulp; a first polymer interlayer comprising PVOH, EVOH, PGA, BVOH, or mixtures thereof; a first inorganic barrier layer comprising one of aluminium oxide (AIOX) and silicon oxide (SiOx); a second polymer interlayer comprising PVOH, EVOH, PGA, BVOH, or mixtures thereof; and a second inorganic barrier layer comprising the other of aluminium oxide (AIOX) and silicon oxide (SiOx).

[0052] Method for Producing a Moulded Pulp Article

[0053] A second aspect of the present invention relates to a method of producing a moulded pulp article, the method comprising the steps of: a) providing a pulp; b) providing a polymer interlayer over the pulp; c) shaping the pulp; and d) providing an inorganic barrier layer over the polymer interlayer.

[0054] The resulting moulded pulp article possesses improved barrier properties to the presence of the polymer interlayer between the pulp and the inorganic barrier layer. Without wishing to be bound by theory, it is believed that the polymer interlayer provides a smooth surface for the deposition of the inorganic barrier layer, thereby improving its barrier performance and reducing the incidence of defects. The moulded pulp article produced by the method may be a moulded pulp article as described in the first aspect of the present invention.

[0055] The polymer interlayer may be provided over the pulp by applying an aqueous dispersion or solution of the polymer in the form of a liquid or a paste. The aqueous dispersion may have a solids content of from 10 to 50% w / w, preferably from 20 to 40% w / w, or more preferably from 25 to 35% w / w. The solids content is the content of the aqueous dispersion that is solids (i.e. is comprised of the polymer). The aqueous dispersion or solution may be applied by any suitable technique, such as spray coating, dip coating, or curtain coating. The aqueous dispersion or solution may be dried prior to the deposition of further layers. Multiple applications may be made so as to obtain the required thickness in the resulting polymer interlayer.

[0056] Alternatively, the polymer interlayer may be provided by placing a polymer film over the pulp. The polymer film may be applied by any suitable technique, such as lamination.

[0057] The inorganic barrier layer may be applied by any suitable technique, such as by vacuum deposition, plasma deposition, atomic layer deposition, or transfer metallization onto the polymer interlayer.

[0058] The method may further comprise the step of providing an organic barrier layer over the inorganic barrier layer. The organic barrier layer may be provided over the pulp by applying an aqueous dispersion or solution of the polymer in the form of a liquid or a paste. The aqueous dispersion may have a solids content of from 10 to 50% w / w, preferably from 20 to 40% w / w, or more preferably from 25 to 35% w / w. The solids content is the content of the aqueous dispersion that is solids (i.e. is comprised of the polymer). The aqueous dispersion or solution may be applied by any suitable technique, such as spray coating, dip coating, or curtain coating. Multiple applications may be made so as to obtain the required thickness in the resulting organic barrier layer.

[0059] Alternatively, the organic barrier layer may be provided by placing a polymer film over the inorganic barrier layer. The polymer film may be applied by any suitable technique, such as lamination.

[0060] The method may further comprise the step of providing a contact layer over the inorganic barrier layer (and over the organic barrier layer, if present). The contact layer may be provided as an aqueous dispersion or a non-aqueous solution of the material that is to form the contact layer, such as a water-insoluble polymer. Typical concentrations of the material are from 10 to 50% w / w, preferably from 20 to 40% w / w, or more preferably from 25 to 35% w / w. The contact layer may be applied by any suitable technique, such as spray coating, dip coating, or curtain coating. Multiple applications may be made so as to obtain the required thickness in the resulting contact layer.

[0061] Alternatively, the contact layer may be provided by placing a polymer film over the organic barrier layer. The polymer film may be applied by any suitable technique, such as lamination.

[0062] The step of shaping the pulp may occur prior to the deposition of further layers. The subsequent layers are provided as dispersions or solutions, and take the shape of the pulp, or are provided as films and are conformed to the shape of the pulp, for example by thermoforming.

[0063] In embodiments, the films and organic layers are formed into a multilayered laminate by cast or film blowing. The multilayered laminate may comprise any or all of the polymer interlayer, the organic barrier layer, and the contact layer. Such multilayered laminates may include tie layers, the tie layers operable to ensure adhesion of the layers to one another.

[0064] Alternatively, the films and organic layers are applied to the shaped pulp using a step- by-step approach. The pulp may be shaped and the following layers applied: i) the polymer interlayer, ii) the polymer interlayer and the inorganic barrier layer, iii) the polymer interlayer, the inorganic barrier layer, and the organic barrier layer; iv) the polymer interlayer, the inorganic barrier layer, the organic barrier layer, and the contact layer; or v) the polymer interlayer, the inorganic barrier layer, and the contact layer.

[0065] Any suitable technique may be used to shape the pulp. One preferred technique is thermoforming.

[0066] Alternatively, for moulding dry pulp, the pulp may be shaped after addition of the polymer interlayer (i.e. the pulp and polymer interlayer are shaped simultaneously). In one embodiment, the polymer interlayer is applied to the pulp and these layers are shaped together and the inorganic barrier layer is then applied. The organic barrier layer and / or the contact layer are then applied using thermoforming. If both the organic barrier layer and the contact layer are being applied, they may be applied simultaneously.

[0067] Uses of the Moulded Pulp Article

[0068] Use of a moulded pulp article as described herein, for packing an edible product for human or animal consumption. Preferably, the moulded pulp article is in the form of a partially open vessel and the edible product is inserted via the opening. Once the moulded pulp article is filled, the opening is sealed, preferably with a polymeric film, a removable cap (e.g. a screw-cap), or a foil.

[0069] A packaged edible product, comprising a moulded pulp article as described herein, at least partially filled with an edible product for human or animal consumption.

[0070] Preferably, said edible product is a powder, a gel, or kibbles and is selected within the list of: ground coffee, soluble coffee, nutrition compositions for infant, adult, or elderly consumption, soup, confectionery or candies, chocolate-based products, dry animal food, dairy products.

Claims

CLAIMS:1 . A moulded pulp article (1) comprising, from outermost layer to innermost layer: a shaped pulp (2); a polymer interlayer (3); and an inorganic barrier layer (4) selected within the list of: metals, metalloids, oxides thereof, or a combination thereof.

2. The moulded pulp article of claim 1 , wherein the polymer interlayer comprises a biodegradable polymer, optionally a polymer selected from polylactic acid (PLA), polyhydroxyalkanoates (PHA), polycaprolactone (PCL) polyglycolic acid (PGA), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene adipate terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch, cellulose, carboxymethyl cellulose, hydroxypropylmethyl cellulose), proteins (such as casein, zein, soy protein, silk), PVOH, EVOH, PGA, BVOH, or mixtures thereof.

3. The moulded pulp article of claim 1 or claim 2, wherein the inorganic barrier layer is selected from aluminium, aluminium oxide (AIOX), silicon oxide (SiOx), or combinations thereof.

4. The moulded pulp article of any preceding claim, further comprising an organic barrier layer (5).

5. The moulded pulp article of claim 4, wherein the organic barrier layer comprises a biodegradable polymer, optionally a polymer selected from PVOH, EVOH, PGA, BVOH, or mixtures thereof.

6. The moulded pulp article of any preceding claim, further comprising a contact layer (6).

7. The moulded pulp article of claim 6, wherein the contact layer comprises a polymer, optionally wherein the polymer is a biodegradable polymer, optionally the biodegradable polymer being selected from polylactic acid (PLA), polyhydroxyalkanoates (PHA), polycaprolactone (PCL) polyglycolic acid (PGA), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene adipate terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch,cellulose, carboxymethyl cellulose, hydroxypropylmethyl cellulose), proteins (such as casein, zein, soy protein, silk) and combinations thereof.

8. A method of producing a moulded pulp article, the method comprising: a) providing a pulp; b) shaping the pulp; c) providing a polymer interlayer over the pulp; and d) providing an inorganic barrier layer over the polymer interlayer.

9. The method of claim 8, the step of shaping the pulp occurs prior to the deposition of any other layer.

10. The method of claim 8, wherein the step of shaping the pulp occurs after deposition of one or more of the other layers.

11. The method of any one of claims 8 to 10, wherein the polymer interlayer comprises a biodegradable polymer, optionally a polymer selected from polylactic acid (PLA), polyhydroxyalkanoates (PHA), polycaprolactone (PCL) polyglycolic acid (PGA), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene adipate terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch, cellulose, carboxymethyl cellulose, hydroxypropylmethyl cellulose), proteins (such as casein, zein, soy protein, silk), PVOH, EVOH, PGA, BVOH, or mixtures thereof.

12. The method of any one of claims 8 to 11 , wherein the inorganic barrier layer is selected from aluminium, aluminium oxide (AIOX), silicon oxide (SiOx), or combinations thereof.

13. The method of any one of claims 8 to 12, further comprising the step of providing an organic barrier layer over the inorganic barrier layer.

14. The method of claim 13, wherein the organic barrier layer comprises a biodegradable polymer, optionally a polymer selected from PVOH, EVOH, PGA, BVOH, or mixtures thereof.

15. The method of any one of claims 8 to 14, further comprising the step of providing a contact layer over the inorganic barrier layer.

16. The method of claim 15, wherein the contact layer comprises a polymer, optionally wherein the polymer is a biodegradable polymer, optionally the biodegradable polymer being selected from polylactic acid (PLA), polyhydroxyalkanoates (PHA), polycaprolactone (PCL) polyglycolic acid (PGA), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene adipate terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch, cellulose, carboxymethyl cellulose, hydroxypropylmethyl cellulose), proteins (such as casein, zein, soy protein, silk) and combinations thereof.

17. Use of a moulded pulp article according to any one of claims 1 to 7, for packing an edible product for human or animal consumption.

18. A packaged edible product, comprising a moulded pulp article according to any one of claims 1 to 7, at least partially filled with an edible product for human or animal consumption.

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