EP4766889A1

EP4766889A1 - Moulded pulp article

Info

Publication number: EP4766889A1
Application number: EP24757970.9A
Authority: EP
Inventors: Nicola GALAFFU; Michael Karlheinz HAUSMANN; Martin HAERI; Gerhard Niederreiter
Original assignee: Societe des Produits Nestle SA; Nestle SA
Current assignee: Societe des Produits Nestle SA; Nestle SA
Priority date: 2023-08-21
Filing date: 2024-08-19
Publication date: 2026-07-01
Also published as: CN121693609A; AU2024328941A1; WO2025040607A1; KR20260052932A

Abstract

The present invention relates to a method of producing a moulded pulp article (1), the method comprising: a) shaping the pulp (2); b) applying a composite phase (3) comprising a polymer and particles (4) of metal, metalloid, or oxides thereof to the pulp; and c) converting the composite phase (3) to a coating (5) comprising the polymer and a continuous barrier (6) at least partially embedded within the polymer, the continuous barrier (6) comprising metal, metalloid, or oxides thereof; as well as moulded pulp articles.

Description

MOULDED PULP ARTICLE

Field of the invention

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

Background of the invention

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 beverage. 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).

The provision of moulded pulp with effective barriers to water vapour 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.

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

Summary of the invention

A first aspect of the present invention relates to a method of producing a moulded pulp article (1), the method comprising: a) shaping the pulp (2); b) applying a composite phase (3) comprising a polymer and particles (4) of metal, metalloid, or oxides thereof to the pulp; and c) converting the composite phase (3) to a coating (5) comprising the polymer and a continuous barrier (6) at least partially embedded within the polymer, the continuous barrier (6) comprising metal, metalloid, or oxides thereof.

Applying the composite phase (3) may comprise applying a thin film comprising the polymer and particles (4) of metal, metalloid, or oxides thereof, the particles (4) being dispersed throughout the polymer, to the surface of the pulp (2). Alternatively, applying the composite phase (3) may comprise applying an aqueous dispersion of polymer and particles (4) of metal, metalloid, or oxides thereof to the surface of the pulp (2).

In embodiments, steps a), b), and c) occur in order. Alternatively, step b) may occur before step a), which occurs before step c). Further alternatively, steps a) and c) may occur simultaneously.

Converting the composite phase (3) to a coating (5) may comprise fusing the particles (4) of metal, metalloid, or oxides thereof, optionally by heating the composite phase (3). Heating the composite phase may comprise exposure of the composite phase to microwave radiation.

The composite phase (3) may further comprise a binder. The binder may be a tetraalkyl orthosilicate, optionally wherein the tetraalkyl orthosilicate is selected from tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), and combinations thereof. Converting the composite phase (3) to the coating (5) may comprise mutually binding the particles (4) of metal, metalloid, or oxides thereof with the binder, optionally by addition or activation of a catalyst.

A second aspect of the present invention relates to a moulded pulp article (1) comprising: a shaped pulp (2); and a coating (5) comprising a continuous barrier (6) , the continuous barrier (6) comprising metal, metalloid, or oxides thereof, and a polymer, wherein the continuous barrier (6) is at least partially embedded within the polymer.

The polymer may be selected from polylactic acid (PLA), polyvinyl alcohol (PVOH), polyhydroxyalkanoates (PHA), polyglycolic acid (PGA), butenediol vinyl alcohol (BVOH), poly(butylene succinate-co-butylene adipate) PBSA, polybutylene adipate terephthalate (PBAT), and combinations thereof.

The metal, metalloid, or oxides thereof may be selected from aluminium, AIOx, SiOx, and combinations thereof.

The coating (5) may comprise between 0.5 and 15 wt% of metal, metalloid, or oxides thereof. The coating (5) may have a thickness of from 1 to 150 pm.

A third aspect of the present invention relate to the use of a moulded pulp article (1) according to the second aspect of the present invention, for packing an edible product for human or animal consumption.

A fourth aspect of the present invention relates to a packaged edible product, comprising a moulded pulp article (1) according to the second 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".

Brief description of the drawings

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:

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) and a coating (5), the coating (5) comprising a continuous barrier layer (6) at least partially embedded within a polymer;

Figure 2 shows a schematic cross section of a precursor to a moulded pulp article (1) according to the present invention. The precursor to the moulded pulp article (1) includes a pulp (2) and a composite phase (3), the composite phase (3) comprising particles (4) of a metal, metalloid, or oxides thereof at least partially embedded within a polymer.

Detailed description of the invention

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 or any other known method of paper coating. Dispersion coating can create a much thinner layer than extrusion 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. by environmentally friendly coating. Another target is to prepare surface of paper material for a vacuum deposition process.

By "fibre", it is meant a cellulosic fibre, which is generally extracted from plants, seeds or trees; such fibres contain not only cellulose molecules, but also hemi-cellulose as well as lignin.

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 sugarcane bagasse, bamboo, and straw. Moulded pulp articles are commonly used for packaging and is widely considered to be sustainable.

By "continuous barrier" it is meant that the material that forms the continuous barrier (e.g. aluminium, AIOx, SiOx, and combinations thereof) is substantially free of through holes. The continuous barrier is not limited to a flat plane or layer following the surface of the underlying moulded pulp, but may have a complex topography due to the stochastic distribution of the particles from which the continuous barrier is formed.

Method of Providing a Moulded Pulp Article

A first aspect of the present invention relates to a method of producing a moulded pulp article, the method comprising: a) shaping the pulp; b) applying a composite phase comprising a polymer and particles of metal, metalloid, or oxides thereof to the pulp; and c) converting the composite phase to a coating comprising the polymer and a continuous barrier at least partially embedded within the polymer, the continuous barrier comprising a metal, metalloid, or oxides thereof.

In embodiments, shaping the pulp comprises pressing the pulp into a mould.

In embodiments, applying the composite phase comprises applying a thin film comprising a polymer and particles of metal, metalloid, or oxides thereof, the particles being dispersed throughout the polymer, to the surface of the pulp. Applying the thin film may comprise placing the thin film in contact with the surface of the pulp and laminating. Such lamination may be achieved simultaneously with the conversion of the composite phase to the coating.

In embodiments, the particles have an uneven distribution through the thickness of the thin film, with the highest concentration being towards the centre of the thin film. Having a higher concentration at the centre of the thin film decreases the overall quantity of particles required to form a continuous barrier. Such a distribution may be obtained by using coextrusion to form the film, the central layer or layers having a higher concentration of particles than the outer layers. It will be appreciated that any suitable method, such as cryo SEM or EDX, may be used to determine such a distribution.

In embodiments, the thin film has a thickness of from 1 to 130 pm. Preferably, the thin film has a thickness of from 10 to 100 pm, more preferably a thickness of from 40 to 90 pm, most preferably a thickness of from 60 to 80 pm. In embodiments, applying the composite phase comprises applying an aqueous dispersion of polymer and particles of metal, metalloid, or oxides thereof to the surface of the pulp. The aqueous dispersion may be 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 comprised of the polymer and the particles. The particles may comprise 0.1 to 5% w/w of the aqueous dispersion, preferably 0.2 to 4% w/w, or more preferably 0.25 to 3.5% w/w. The polymer may comprise 5 to 50% w/w of the aqueous dispersion, preferably 10 to 40% w/w, or more preferably 20 to 30% w/w. The particles may be present in an amount of 0.5 to 15% w/w of the polymer, preferably from 1 to 10% w/w, or more preferably from 3 to 7% w/w. The aqueous dispersion may be dried prior to conversion to a coating. Alternatively, the aqueous dispersion is dried as it is converted to the coating.

In embodiments, the aqueous dispersion is applied in a thickness of from 1 to 40 pm. Preferably, the aqueous dispersion is applied in a thickness of from 5 to 35 pm, more preferably a thickness of from 20 to 30 pm. In embodiments, the multiple applications of the aqueous dispersion are made in order to increase the total quantity of material applied to the pulp. For example, up to 2 applications, up to 4 applications, or up to 6 applications of the aqueous dispersion may be made.

Steps a), b), and c) may occur in order. In other words, the pulp is shaped, the composite phase is applied to the shaped pulp, and the composite phase is then converted to the coating in order to provide the moulded pulp article.

In an embodiment, step b) occurs before step a), which occurs before step c). In other words, the pulp may be provided unshaped (for example, as a flat sheet) and the composite phase applied. The pulp with its composite phase is then formed into the shape of the moulded pulp article and the composite phase of the shaped pulp is then converted to the coating.

Steps a) and c) may occur simultaneously after step b). In other words, the pulp may be provided unshaped (for example, as a flat sheet) and the composite phase applied. The pulp is then formed into the shape of the moulded pulp article as the composite phase is converted to the coating.

Converting the composite phase to a coating may comprise fusing the particles of metal, metalloid, or oxides thereof into a coherent mass (i.e. the continuous barrier). This may be achieved by subjecting the particles to heat. In one embodiment, the particles are heated using microwave radiation. Advantageously, heating using microwave radiation primarily and rapidly heats the particles at their contact points, thereby limiting exposure of the polymer or pulp to heat, minimizing degradation of these materials.

Where microwave radiation is used to convert the composite phase to the coating, the microwave radiation may have a power of from 600 to 1200 W/cm², preferably from 700 to 1100 W/cm², more preferably from 800 to 1000 W/cm². The microwave radiation may be applied for a time period of from 0.5 to 10 s, preferably from 1 to 5 s. Any suitable method or apparatus may be used to apply the microwave radiation to the composite phase.

In embodiments, the composite phase further comprises an organic acid, such as a carboxylic acid (e.g. acetic acid, citric acid, malic acid, and tartaric acid) or a sulfonic acid (e.g. methanesulfonic acid and p-toluenesulfonic acid). Without wishing to be bound by theory, the organic acid is thought to induce partial dissolution and softening of the particles, further enhancing their fusion. Where used, the organic acid may be used in an amount of 0.1 to

5% w/w with respect to the particles, preferably 0.5 to 3% w/w with respect to the particles, more preferably 1 to 2% w/w with respect to the particles.

In embodiments, the composite phase further comprises a binder. The binder is operable to covalently link to itself and to the surface of the particles. The binder may be a tetraalkyl orthosilicate, for example, tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), or combinations thereof. These binders additionally covalently bond to the surface of the pulp fibres.

Where used, the binder is present in an amount of from 0.1 to 10% w/w with respect to the particles, preferably from 0.5 to 7% w/w with respect to the particles, more preferably from 1 to 5% w/w with respect to the particles.

Where a binder is used, converting the composite phase to a coating comprises mutually binding the particles of metal, metalloid, or oxides thereof with the binder to form the continuous barrier. For the tetraalkyl orthosilicate binders, this involves hydrolysis of the hydroxyl groups to leave a silicon dioxide network to which the particles are bound. Conversion of the composite phase comprising a binder to the coating may comprise heating the composite phase and/or the addition of a catalyst. Examples of catalysts include acids, such as hydrochloric acid or acetic acid.

In embodiments, conversion of the composite phase comprises both fusing of the particles, for example, via heating as described above, and the mutual binding of the particles with a binder.

Moulded Pulp Article

A second aspect of the present invention relates to a moulded pulp article comprising: a shaped pulp; and a coating comprising a continuous barrier, the continuous barrier comprising metal, metalloid, or oxides thereof, and a polymer, wherein the continuous barrier is at least partially embedded within the polymer.

The continuous barrier may be formed by fusing particles of metal or metal oxide into a coherent mass. Alternatively, or additionally, the continuous barrier may be formed by mutually binding particles of metal or metal oxide.

The coating may further comprise a binder. The binder may be a tetraalkyl orthosilicate, such as tetramethyl orthosilicate, tetraethyl orthosilicate, or combinations thereof.

The coating having may have a thickness of from 1 to 150 pm. In embodiments, the coating has a thickness of from 15 to 130 pm, preferably from 20 to 100 pm, more preferably from 30 to 80 pm, or most preferably from 40 to 60 pm. In alternative embodiments, the coating has a thickness of from 5 to 35 pm, more preferably a thickness of from 8 to 20 pm, most preferably a thickness of from 10 to 15 pm.

The moulded pulp article may be a can, a cup, a tray, a bottle, or a capsule.

The moulded pulp article may be produced by the method of the first aspect of the present invention.

Particles of metal, metalloid, or oxides thereof

The particles of metal, metalloid, or oxides thereof may be selected from aluminium, AIOx, SiOx, or combinations thereof. In embodiments, the particles comprise between 0.5 and 15 wt% of the coating. The particles are required to be present in a quantity sufficient to form a continuous network on conversion of the composite phase to the coating. Preferably, the particles comprise between l and 10 wt% of the coating, more preferably between 1.5 and 8 wt% of the coating, most preferably between 2 and 5 wt% of the coating.

The particles may have an average particle size of between 10 nm and 1 pm, preferably between 50 and 750 nm, more preferably 100 and 500 nm. Any suitable technique may be applied to measure the particle size, for example, scanning electron microscopy (SEM) as is described in ISO 19749:2021 or transmission electron microscopy (TEM) as is described in ISO 21363:2020.

Polymer

In embodiments, the polymer is water dispersible. Being water dispersible enables the use of aqueous dispersions in the production of the moulded articles, which are more environmentally friendly and cost effective. In embodiments, the polymer is biodegradable. Being biodegradable enables the moulded pulp article to be biodegradable. Preferable, the polymer is selected from polylactic acid (PLA), polyvinyl alcohol (PVOH), polyhydroxyalkanoates (PHA), polyglycolic acid (PGA), butenediol vinyl alcohol (BVOH), poly(butylene succinate-co-butylene adipate) PBSA, polybutylene adipate terephthalate (PBAT), and combinations thereof.

Uses of the Moulded Pulp Article

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. 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. 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

1. A method of producing a moulded pulp article (1), the method comprising: a) shaping the pulp (2); b) applying a composite phase (3) comprising a polymer and particles (4) of metal, metalloid, or oxides thereof to the pulp; and c) converting the composite phase (3) to a coating (5) comprising the polymer and a continuous barrier (6) at least partially embedded within the polymer, the continuous barrier (6) comprising metal, metalloid, or oxides thereof.

2. The method according to claim 1, wherein applying the composite phase (3) comprises applying a thin film comprising the polymer and particles (4) of metal, metalloid, or oxides thereof, the particles (4) being dispersed throughout the polymer, to the surface of the pulp (2).

3. The method according to claim 1, wherein applying the composite phase (3) comprises applying an aqueous dispersion of polymer and particles (4) of metal, metalloid, or oxides thereof to the surface of the pulp (2).

4. The method according to any one of claims 1 to 3, wherein: i. steps a), b), and c) occur in order; or ii. step b) occurs before step a), which occurs before step c); or iii. wherein steps a) and c) occur simultaneously.

5. The method according to any one of the preceding claims, wherein converting the composite phase (3) to a coating (5) comprises fusing the particles (4) of metal, metalloid, or oxides thereof, optionally by heating the composite phase (3).

6. The method according to claim 5, wherein heating comprises exposure to microwave radiation.

7. The method according to any one of the preceding claims, wherein the composite phase (3) further comprises a binder.

8. The method according to claim 7, wherein the binder is a tetraalkyl orthosilicate, optionally wherein the tetraalkyl orthosilicate is selected from tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), and combinations thereof.

9. The method according to claim 7 or claim 8, wherein converting the composite phase (3) to the coating (5) comprises mutually binding the particles (4) of metal, metalloid, or oxides thereof with the binder, optionally by addition or activation of a catalyst.

10. A moulded pulp article (1) comprising: a shaped pulp (2) ; and a coating (5) comprising a continuous barrier (6) , the continuous barrier (6) comprising metal, metalloid, or oxides thereof, and a polymer, wherein the continuous barrier (6) is at least partially embedded within the polymer.

11. The moulded pulp article (1) according to claim 10, wherein the polymer is selected from polylactic acid (PLA), polyvinyl alcohol (PVOH), polyhydroxyalkanoates (PHA), polyglycolic acid (PGA), butenediol vinyl alcohol (BVOH), poly(butylene succinate-co-butylene adipate) PBSA, polybutylene adipate terephthalate (PBAT), and combinations thereof.

12. The moulded pulp article (1) according to claim 10 or claim 11, wherein the particles (4) of metal, metalloid, or oxides thereof are selected from aluminium, AIOx, SiOx, and combinations thereof.

13. The moulded pulp article (1) according to any one of claims 10 to 12, wherein the coating (5) comprises between 0.5 and 15% w/w of metal, metalloid, or oxides thereof.

14. The moulded pulp article (1) according to any one of claims 10 to 13, wherein the coating (5) has a thickness of from 1 to 150 pm.

15. Use of a moulded pulp article (1) according to any one of claims 10 to 14, for packing an edible product for human or animal consumption.

16. A packaged edible product, comprising a moulded pulp article (1) according to any one of claims 10 to 14, at least partially filled with an edible product for human or animal consumption.