WO2024147011A1

WO2024147011A1 - Method

Info

Publication number: WO2024147011A1
Application number: PCT/GB2024/050008
Authority: WO
Inventors: Fanya ISMAIL; Sheila FATTAH
Original assignee: Sol-Gel Materials & Applications Ltd
Priority date: 2023-01-05
Filing date: 2024-01-04
Publication date: 2024-07-11

Abstract

A method comprising applying a wetting agent to air-laid pulp to form an intermediate pulp and hot-pressing the intermediate pulp to form a moulded product. The pulp may be formed from a fibrous raw material. The wetting agent may include a functional additive such as a sol. A sol may include a solvent, an alkoxide, and optionally a catalyst. The air-laid pulp, intermediate pulp, and/or moulded product may be free or substantially free of thermoplastic polymers and/or hydrocarbon-based plastics. The moulded product may be a fibre-based bubble wrap. The fibre-based bubble wrap may be formed from reel-to-reel processes.

Description

METHOD

INTRODUCTION

[0001] The present invention relates to the processing of pulp and methods of achieving the same. More particularly, the present invention relates to imparting one or more beneficial characteristics to a product formed from air-laid pulp.

[0002] Paper, cardboard and other materials are commonly used as packaging for commercial products. The material properties of a product, such as the permeability of packaging materials to water, oils and other fluids may be controlled through use of impermeable polymeric materials such as plastics, or composites. In many industries such as the food and beverages industry, polymeric materials such as thermoplastics may be applied to otherwise permeable media to facilitate the retention of liquid products within a particular packaging item. In other examples, lignin- or cellulose-based paper feedstocks treated with polymeric material may be subjected to high temperatures to treat, cure or fuse the lignin or cellulose present in the paper feedstock to seal the pore structure of the material. Similar methods may also be used to prevent the ingress of fluid into an item that may become compromised by exposure to water, air or other fluids. Where polymeric materials such as plastic are used, the plastic materials are generally manufactured from hydrocarbon feedstocks and their manufacture presents an associated environmental cost. The materials or chemicals used to manufacture such plastics and the associated by-products may also be toxic. Some plastics may also degrade over time or through use to produce microplastics or to otherwise release potentially harmful species. Similarly, in processes where paper feedstocks are subjected to high temperatures, energy efficiency is often poor and some processes result in the release of undesirable gas or vapour by-products. Consequently, there are ongoing health and environmental concerns in relation to the manufacture of many common paper and cardboard packaging materials.

[0003] Papers and cardboards are generally formed from mixtures of plant-based fibres. Raw materials rich in lignin and/or cellulose such as wood or plant material are the most common raw material feedstocks and these materials are processed into pulp from which paper products may be manufactured. Paper pulp exists in several different forms such as wet pulp or dry pulp that may be used in the formation of paper and/or cardboard products with different properties and purposes. For the avoidance of doubt, the term ‘paper’ as used herein is intended to encompass ‘cardboard’ and so a cardboard product would be considered to be a paper product for the purposes of the information provided herein. Moreover, the term ‘pulp’ is intended to mean a material formed from primarily plant-based fibrous material. [0004] Wet pulps are pulp materials that use a liquid-based solvent as a carrying medium for the fibrous raw material medium during processing. The liquid carrying medium for wet pulp is usually water due to its abundance, availability and relatively low cost. However, other solvents may be used including: alcohols such as methanol and ethanol; acids such as acetic acid; organic solvents such as acetone; and combinations of such solvents, may also be used depending on the nature and requirements of the pulping process. Wet pulps are typically formed by shredding and/or masticating a raw material feedstock in a volume of water to disperse the fibrous material and form the pulp. The wet pulp is then transferred via one or more optional further processes to a press, mould, or similar device where the pulp may be shaped or formed into sheets. Wet pulp products may contain in excess of 50% liquid by weight following shaping and so much of this liquid must generally be removed prior to use and/or during processing of the pulp. In some examples, wet pulp may contain up to approximately 90% liquid. The residual liquid carrying medium is usually removed via one or more drying processes. The formation of a product from wet pulp therefore requires significant volumes of liquids such as water and large amounts of energy throughout the manufacturing process. Large volumes of liquids such as water may also require to be cycled for long periods of time, which makes wet pulp processes vulnerable to bacterial or fungal growth within manufacturing apparatus. To address this issue, large quantities of disinfectant or anti-fungal agents are often circulated through the manufacturing system to prevent an adverse accumulation of bacteria and/or fungi. The spent disinfectant must also be disposed which represents additional cost and poses further environmental challenges.

[0005] Dry pulps may be formed by drying wet pulp or by otherwise utilising formation processes that forego the use of liquid carrying media such as water. In general, dry pulps have a high capacity to absorb water and so are often used to form absorbent products such as nappies, tissues, feminine hygiene products, and the like. Fluff pulp, or air-laid pulp, particularly forgoes the use of liquids such as water as a processing medium and instead utilises air or other gases as a means of carrying fibres. In general, air-laid pulp is shredded and reformed or re-laid by carrying and/or spinning the fibres in and gaseous medium. The air-laid pulp may be treated with one or more sizing agents prior to or during the carrying and/or spinning process to impart one or more characteristics to the air-laid pulp. Some air-laid pulp is formed from softwood due to the material’s propensity to produce lengthy fibres of low density. Air-laid pulp may form products with different characteristics than those produced from wet pulp or dry pulp formed by merely drying wet pulp. For example, air-laid pulp may be isotropic. In another example, air-laid pulp may have a greater pore volume than an equivalent wet pulp which has been subsequently dried. This property makes fluff pulp or air-laid pulp particularly beneficial for the formation of products which must carry a proportionally high volume of liquid in use such as cleaning pads or wet wipes. The formation of a product from dry pulp generally involves treatment of the pulp with plastics and/or a binder which are exposed to high temperatures to melt the plastic and/or binder prior to the use of a mould or press to impart a desired shape.

[0006] The properties of rigidity, strength, and water and/or gas resistance or impermeability are desirous in paper products used for the packaging and storage of perishable goods such as food and drink. Paper and cardboard packaging may need to protect a product stored or contained within the packaging. Papers and cardboards are not inherently fluid resistant or impermeable due to the material’s intrinsic pore structure and so papers for packaging are typically treated or processed to provide a fluid barrier, material strength, or other resistances. Wet pulp-derived products are often coated with a plastic coating following formation to allow the product to resist the ingress of fluids. Dry pulp-derived products may be subjected to a hot-press process where the pulp has been optionally coated with a plastic or polymer precursor. The application of heat during the hot-press process is believed to ‘set’ or ‘cure’ the lignocellulosic fibres in the paper pulp and any plastic or polymer precursor applied to the pulp prior to the hot-press step. In practice, 'hot-press’ processes for pulp processing operate at temperatures of around 100 °C to 300 °C as these temperatures are believed to cause the physical and chemical structure of the lignocellulosic fibres to change, thus providing a material with mechanical characteristics similar to plastics.

[0007] The inventor of the present invention has appreciated that moulded products formed from air-laid pulps may be formed without the use of large volumes of water, high temperatures, hydrocarbon-based polymers and/or thermoplastics, and complex manufacturing apparatus. In particular, the inventor of the present invention has appreciated that moulded products formed from air-laid pulp may have one or more desirable characteristics including at least partial resilient deformability and/or smoothness. Furthermore, the inventor of the present invention has appreciated that a fluid resistant or impermeable moulded paper product may be formed by applying a hot-press process, and optionally a cold-press process, to an air-laid pulp in the presence of a wetting agent and/or a functional additive such as a sol. The process may also impart the moulded product with one or more other desirable characteristics depending upon the wetting agent or functional additive.

[0008] According to one aspect of the invention, there is provided a method comprising applying a wetting agent to air-laid pulp to form an intermediate pulp, and hot-pressing the intermediate pulp to form a moulded product. The air-laid pulp, intermediate pulp, and/or moulded product may be free or substantially free of thermoplastic polymers and/or hydrocarbon-based plastics. The method may further comprise applying a functional coating and/or barrier to the intermediate pulp or moulded product. The method may further comprise additionally hot- and/or cold-pressing the air-laid pulp, intermediate pulp, or moulded product. The moulded product may be a water resistant or water impermeable moulded product. The wetting agent may be applied to the air-laid pulp by brushing, spraying, spray drying, rolling, dipping, dropping, injecting, transferring, submersion, immersion, mixing, spreading, blading, padding, or any combination thereof. The wetting agent may be applied to the air-laid pulp by spraying. Hot-pressing the intermediate pulp may be carried out at a temperature of greater than 100 °C, optionally equal to or greater than 150 °C, equal to or greater than 200 °C, equal to or greater than 250 °C, or equal to or greater than 300°C. In contrast, cold-pressing the intermediate pulp may be carried out at a temperature less than 100 °C, optionally less than 50 °C. Hot-pressing the intermediate pulp may comprise pressing the intermediate pulp into at least one mould, pressing the intermediate pulp between at least one plate and at least one other surface, or any combination thereof. Additionally hot- and/or cold-pressing the air-laid pulp, intermediate pulp, or moulded product may also comprise pressing the intermediate pulp into at least one mould, pressing the intermediate pulp between at least one plate and at least one other surface, or any combination thereof. The mould, plate or other surface used to hot-press and/or cold-press the air-laid pulp, intermediate pulp, or moulded product may comprise one or more fluid escape elements configured to allow fluid, optionally wetting agent in the form of vapour and/or liquid, to escape, optionally wherein the one or more fluid escape elements comprise one or more holes, vents, apertures, flow passages, conduits, pipes, pathways, or any combination thereof. The method may further comprise applying heat to dry the air-laid pulp, intermediate pulp, or product. The method may further comprise drying the air-laid pulp, intermediate pulp, or product without the direct application of energy. The wetting agent may comprise water. The wetting agent may consist essentially of water. The wetting agent may comprise a sol. The sol may comprise a solvent, an alkoxide, and a catalyst. The sol may further comprise a biopolymer. The biopolymer may comprise a starch. The starch may comprise a cationic starch. The cationic starch may be selected from quaternary ammonium type cationic starch, tertiary ammonium type cationic starch, and any combination thereof. The biopolymer may comprise a flour. The flour may comprise 5 to 85% starch, 0 to 30% hemi-cellulose, 0 to 50% cellulose, 0 to 25% lignin, 0 to 35% protein and 0 to 25% ash. The flour may be selected from the group wheat flour, barley flour, lentil flour, bamboo flour, corn flour, oat flour, rye flour, buckwheat flour, rice flour, chickpea flour, green pea flour, or any combination thereof. The catalyst may be at least one of an acid and a base. The catalyst may be selected from hydrochloric acid, citric acid, nitric acid, acetic acid, sodium hydroxide, potassium hydroxide, ammonia, and any combination thereof. The alkoxide may be selected from silicon alkoxides, metal alkoxides, phosphorus alkoxides, and any combination thereof. The alkoxide may be selected from npropyltriethoxysilane, tetrapropyl orthosilicate, titanium(IV) tert-butoxide, titanium(IV) isopropoxide, triethyloxysilane, methyltriethyloxysilane, triethoxy(octyl)silane, phenyltriethoxysilane, titanium(iv) ethoxide, triethoxy-silylcyclopentane, (3-glycidyloxypropyl) trimethoxysilane, cyclopentyltriethoxysilane, 3-amino-propyltriethoxysilane, triethoxy-3- (2imidazolin-1-yl)propylsilane, and any combination thereof. The solvent may comprise water, one or more alcohols, and any combination thereof. The solvent may comprise methanol, ethanol, isopropanol, butanol, ethylene glycol or any combination thereof. The wetting agent may comprise one or more functional additives. The one or more functional additives may comprise photoinitiators, resins, oils, dyes (including food grade organic colours), salts, anti-microbial agents, mineral or other inorganic particles, surfactants, biopolymers, composite particles and/or metal particles. The wetting agent may deliver the one or more functional additives into the internal structure of the air-laid pulp. Hot-pressing the intermediate pulp may include applying a pressure of at least 1000 kg/m² to at least a part of the intermediate pulp. Hot-pressing the intermediate pulp may comprise applying a pressure of about 6000 kg/m² to at least part of the intermediate pulp. Hot-pressing the intermediate pulp may comprise applying pressure to a portion of the intermediate pulp for a time of from less than 1 second to up to 10 seconds, optionally wherein pressure is applied for less than 5 seconds. The moulded product may be a fibre-based moulded bubble wrap. The moulded product may be a food or beverage packaging product. The product may be a non-food or beverage packaging product.

[0009] According to another aspect of the invention, there is provided a fluid resistant or fluid impermeable fibre-based packaging material comprising air-laid pulp comprising a moulded product formed by the method of the present invention. The fibre-based packaging material may comprise a sol comprising a solvent, an alkoxide, and optionally a biopolymer. The fibre-based packaging material may be a fluid resistant or fluid impermeable fibre-based bubble wrap. The fibre-based bubble wrap may be formed using a reel-to-reel process, a reel-to-sheet process, a sheet-to-reel process, or a sheet-to-sheet process. The fibre-based packaging material may be a fluid resistant or fluid impermeable fibre-based packaging peanut.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention will now be described with reference to the following drawings, in which:

[0011] Figure 1 shows a flow diagram of a method according to the present invention;

[0012] Figure 2 shows a flow diagram of a method including various optional method steps which may be carried out within the scope of the present invention; [0013] Figures 3A to 3E show cross-sections of fibre-based bubble wraps that may be formed using the methods disclosed herein.

DETAILED DESCRIPTION

[0014] The method of the present invention aims to provide moulded air-laid pulp-based products with particular characteristics without the use of environmentally detrimental materials such as hydrocarbon-based plastics or the application of excessive energy. Figure 1 shows a flow diagram of a method 100 according to the present invention. The method 100 includes applying 101 a wetting agent to air-laid pulp to form an intermediate product, and hot-pressing 102 the intermediate pulp to form a moulded product.

[0015] The wetting agent may be any suitable wetting agent that allows the air-laid pulp structure to become at least partially malleable, deformable, mouldable, or otherwise shapeable. Without being bound by theory, the presence of a wetting agent is believed to act as a lubricant and/or to soften the fibrous material of the air-laid pulp such that the fibres may move or bend without breaking. The intermediate pulp formed following application of the wetting agent to the air-laid pulp may therefore be shaped into a moulded product with relative ease without the need to heat the pulp significantly above ambient temperatures. The inventor of the present invention has also discovered that applying a wetting agent to air-laid pulp or similar pulp formed without the use of water or other liquids may impart fluid resistance to a moulded product formed from said pulp. The use of a wetting agent may also improve the surface smoothness, strength, and/or resilience of a product formed by moulding air-laid pulp. The application of a wetting agent may therefore improve the effectiveness of the hot-press process or reduce the cracking or breakage that occurs when air-laid pulp is pressed to form a moulded product. The products thus formed have been found to exhibit increased resistance to further or subsequent deformation when water or other liquids are applied to the final moulded product. The products may exhibit at least partial elasticity and/or be resiliently deformable. Without being bound by further theory, it is believed that the properties of fibres following the formation of air-laid pulp are uniquely suited to the formation of resilient and resiliently deformable products under pressure due to the absence of water, or the absence of water other than inherent water, from the internal structure of the air-laid pulp. It is further believed that a wetting agent, and particularly a wetting agent including water, applied during the product formation process hydrates or reacts with the fibre surface and initiates physiochemical reactions within the fibre matrix at an early stage that would otherwise be initiated by later exposure of the moulded product to water or other liquids. Consequently, the hydration and related reactions initiated by application of the wetting agent to the air-laid or similar pulp during the process of formation of the product may prevent or reduce the extent to which such physiochemical reactions occur when further water or other liquids are applied to the finished moulded product. The reactions initiated in the air-laid pulp by the application of the wetting agent may result in a moulded product with a more closed pore structure than would be obtained by pressing the air-laid pulp in the absence of the wetting agents. The moulded product may therefore better resist deformation, damage, or decomposition via exposure to water or other liquids after the formation of the moulded product due to a reduction in the potential for such water or other liquids to react, interact, and/or permeate with the material forming the product. Wetting the air-laid pulp may also improve the efficiency of the method by allowing the pulp to be processed at greater speed.

[0016] The methods and processes described herein may be advantageous when compared to methods and processes known in the art. Some known processes apply a binder such as a polymeric binder in advance of forming or shaping a fibre product. Application of the binder in this manner typically results in a product which cannot be effectively recycled either due to the challenges associated with separating the binder and the fibre products or due to the inherent non-recyclable nature of the binders used. Other processes and methods may apply a sealing agent, functional additive, or other agent following the shaping or formation of the fibre product. Such processes may utilise solvents that react with and/or open the fibre structure which may weaken the product thus formed or reduce the products’ ability to resist the ingress of moisture in the longer term. Processes and methods of this nature may also have a higher environmental cost or energy consumption. The methods and processes described herein which apply a wetting agent during a hot-press process address at least some of these challenges associated with existing methods. More particularly, the methods and processes described herein may use pulp and/or materials that are free, entirely free, or substantially free of plastic(s), binder(s), sizing agent(s), additive(s), filler(s), retention aid(s), wet strength agent(s), dry strength agent(s), defoamer(s), or any combination thereof. The skilled person, with the benefit of this disclosure, will understand the range of additives that may be explicitly and intentionally excluded from the pulp and/or materials used in the methods and processes described herein. However, such additives may be included where a particular application or end-use necessitates the use of such an additive. The methods and processes of the invention may still be carried out in the presence of one or more of the species that may be explicitly excluded should such inclusion be desired by the skilled person.

[0017] The wetting agent may include one or more functional additives. The one or more functional additives, where present, may be selected to impart one or more characteristics, properties or other behaviours to the air-laid pulp, intermediate pulp and/or moulded product. In some examples, the one or more functional additives may include photoinitiators, resins, oils, dyes (including food grade organic colours), salts, anti-microbial agents, mineral or other inorganic particles, surfactants, biopolymers, composite particles and/or metal particles, or any combination thereof. The one or more functional additives may include one or more adhesives or binders. It may be advantageous for the one or more functional additives, where present, to exclude materials that may limit the recyclability or reprocessibility of the moulded product. For example, it may be advantageous for the one or more functional additives to exclude plastic. The wetting agent may deliver the one or more functional additives onto the surface and/or into the internal structure of the air-laid pulp. Without being bound by theory, the functional characteristics imparted to air-laid pulp, intermediate pulp and/or moulded products with which a wetting agent with a functional additive is used may arise due to: the formation of a coating upon one or more surfaces of the air-laid pulp, intermediate pulp and/or moulded product; and/or the filling of pore volume and/or internal void space with one or more functional additives delivered into the pore volume and/or internal void space by the wetting agent. Moreover, in some situations, during or following application, some functional additives may at least partially form a transient nanodispersion, microdispersion or suspension in addition to the formation of a crosslinked coating. A cross-linked coating and/or the transient nanodispersion, microdispersion or suspension may perform a filling function by partially or fully blocking or obstructing otherwise porous or permeable passages on the surface of a product. Therefore, coating a product with a functional additive may result in a combination of a functional additive coating including discrete functional or reactive particles. Moreover, some functional additives may be present in solution or fine suspension and so be carried into internal void spaces of a product or intermediate product by a wetting agent. When a product or intermediate product is subsequently dried or otherwise treated then the functional additive may partially or fully fill and/or coat the internal void spaces of a product or intermediate product. One example of a functional additive that may act in this manner is a sol. The wetting agent including one or more functional additives may therefore act as coating, filler, and binder simultaneously for materials of a porous and/or permeable nature.

[0018] The wetting agent may be a liquid. The wetting agent may comprise, consist of, or consist essentially of water, one or more alcohols, any other suitable solvent such as an organic solvent, or any combination thereof. Where the solvent comprises an organic solvent, the organic solvent may comprise white spirit. Where present, the one or more alcohols of the solvent may comprise methanol, ethanol, butanol, ethylene glycol, isopropanol, industrial denatured alcohol, isomers of any preceding alcohol such as tert-butanol, any other suitable alcohol, and any combination thereof. The wetting agent may include, consist of, or consist essentially of water. The wetting agent may include, consist or, or consist essentially of a sol. In this context, the term ‘sol’ refers to a dispersion of colloidal particles in a liquid solvent. A sol may also be referred to as a sol mixture. Many sols formed from small colloidal particles are substantially clear and colourless. For example, sols formed from silicon-based functional materials will generally be clear and colourless as the particles forming the sol are sufficiently small that they do not scatter light. Some sols formed from larger particles may be coloured and/or at least partially opaque. For example, sols formed from titanium-based functional materials may be visibly white. Sols may form impermeable and/or anti-microbial and/or alternatively functional coating compositions when applied to a range of materials. Consequently, sols may be used as a barrier and/or as an antimicrobial coating composition and may provide other functionalities such as hydrophobicity, oleophobicity, anti-fouling, anti-biofouling, stain resistance, optical transparency, optical opacity, anti-reflectivity, and adhesion promotion. Sols used as a barrier may provide a barrier to liquids, vapours and/or gases such as oxygen. Sols may comprise readily available natural materials that ensure the resulting sols are inexpensive. Furthermore, some sols have been shown to provide a durable and thermally resistant coating, demonstrating that sols may form resilient and long- lasting functional coatings.

[0019] A sol may be formed by dispersing one or more materials of suitably small particle size in a solution. Some sols may further comprise additional components such as a catalyst or functional components. The sols suitable for use in the methods of the invention may be any sol that may be applied, coated or incorporated into an air-laid pulp to impart a beneficial property or characteristic to the resulting product formed from the intermediate pulp thus formed. Sols suitable for use in the present invention will generally comprise a functional material and a solvent. The functional material may be present in the sol in any suitable proportion. For example, the functional material may be present in the sol in an amount of about 0.1%, about 0.5%, about 1 %, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11 %, about 12%, about 13%, about 14%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, or any other suitable quantity by total weight of sol. In an example, the methods of the invention may involve the use of sols comprising a solvent, a functional metal alkoxide, and optionally a biopolymer and/or optionally a catalyst. The term ‘metal alkoxide’ includes alkoxides comprising metals, organically modified alkoxides comprising metals, alkoxides comprising metalloids, and organically modified alkoxides comprising metalloids. The solvent used in the formation of the sol may comprise water, one or more alcohols, any other suitable solvent, or any combination thereof. Where present, the one or more alcohols may comprise methanol, ethanol, butanol, ethylene glycol, isopropanol, any other suitable alcohol, and any combination thereof. Bio-solvents such as bio-ethanol may also be used. Prior to its use as a wetting agent, the sol may be combined with one or more further solvents, wherein the further solvents are the same as or different from the solvents used in the formation of the sol. Combination of the sol with one or more further solvents may initiate the precipitation of the sol such that it may be applied as a wetting agent during the time period across which the sol precipitates. Methods of initiating precipitation of sols are described further in WO 2021/160979. The biopolymer, where present, may comprise starch-based polymer, hemi-cellulose-based polymer, cellulose-based polymer, lignin-based polymer, chitosan-based polymer, any other suitable biopolymer or modified biopolymer, and any combination thereof. The sol may additionally, or alternatively, comprise one or more flours derived from natural materials. Suitable flours may include oat flour, barley flour, rye flour, wheat flour, rice flour, bamboo flour, lentil flour, chickpea flour, pea flour, corn flour, or any combination thereof. Where the sol comprises a functional metal alkoxide, the alkoxide will generally conform to the general formula M(OR)_x or Rc-M(OR)_X, where “M” denotes any metal forming the metal alkoxide which may hydrolyse in the presence of a suitable solvent. “R” and “R_c” denote alkyl radicals of typically 1 to 30 carbon atoms which may take any suitable form such as straight chain, branched, aromatic or complex, “x” will generally equate to the valence of the corresponding metal ion “M”. In an example, R may be a methyl, ethyl, propyl or butyl radical. Where a metal ion “M” has a valency in excess of 1 , each R group may be the same. Alternatively, one or more R groups may be different from one or more or all other R groups. Rc denotes any suitable organic group which will form and maintain a covalent bond with the metal “M” following hydrolysis of the alkoxide. In some examples, R and Rc may be the same. In other examples, R and Rc may be different. Any suitable metal alkoxide may be used. Examples of suitable metal alkoxides include Si(OR)4, Ti(OR)4, AI(OR)s, Zr(OR)s and Sn(OR)4 as well as R_c-Si(OR)3, Rc-Ti(OR)s, Rc-AI(OR)2, Rc-Zr(OR)2 and R_c-Sn(OR)3. In specific examples, R may be the methyl, ethyl, propyl or butyl radical. In some specific examples, Rc may be a phenyl group, a cyclopentyl group, or any other suitable organic group capable of maintaining a covalent bond to the metal. The metal of the metal alkoxide may comprise silicon, titanium, aluminium, zirconium, tin, or any other suitable metal. In particular examples, the metal alkoxides may be selected from the group comprising Ti(isopropoxy)₄, Al(isopropoxy)₃, Al(secbutoxy)3, Zr(n-butoxy)4, Zr(n-propoxy)4, n-propyltriethoxysilane, tetrapropyl orthosilicate, titanium(IV) tert-butoxide, titanium(IV) isopropoxide, triethyloxysilane, methyltriethyloxysilane, triethoxy(octyl)silane, phenyl-triethoxysilane, titanium(iv) ethoxide, triethoxy-silylcyclopentane, (3glycidyloxypropyl) trimethoxysilane, cyclopentyltriethoxysilane, 3-amino-propyltriethoxysilane, triethoxy-3-(2-imidazolin-1-yl)propylsilane, and any combination thereof. In selected examples, the metal alkoxides may be selected from the group comprising tetraethoxysilane, triethyloxysilane, phenyltriethoxysilane, methyltriethyloxysilane, and any combination thereof. In further selected examples, the metal alkoxides may be selected from the group comprising tetrapropyl orthosilicate, titanium(IV) tert-butoxide, titanium(IV) isopropoxide, triethyloxysilane, methyltriethyloxysilane, triethoxy(octyl)silane, phenyl-triethoxysilane, titanium(iv) ethoxide, triethoxy-silylcyclopentane, (3-glycidyloxypropyl) trimethoxysilane, cyclopentyltriethoxysilane, or any combination thereof. In additional selected examples, the metal alkoxide may be selected from the group comprising Ti(isopropoxy)4, Al(isopropoxy)₃, Al(sec-butoxy)s, Zr(n-butoxy)4, Zr(npropoxy)₄, and n-propyltriethoxysilane-based alkoxides, and any combination thereof. Suitable catalysts for use in sols include at least one of an acid or a base. Examples of acid catalysts include hydrochloric acid, citric acid, nitric acid and acetic acid. Examples of basic catalysts include sodium hydroxide, potassium hydroxide and ammonia.

[0020] A sol may be prepared by dispersing a functional material of suitably small particle size in a solvent and optionally adding a catalyst. The functional material may be a particle with at least one dimension in the range of approximately 1 nm to 1 pm. An alternative method of making a sol involves dispersing a functional material in a solution which optionally comprises a catalyst and then adding a biopolymer and/or one or more other functional additives. Where a biopolymer and/or one or more other functional additives are present, a sol comprising a functional material may generally be stored for a period of time, prior to addition of the biopolymer and/or the one or more other functional additives. Additional functional additives may be added at any stage during the method of making the sol. For example, in a sol comprising a biopolymer the additional functional additive may be added before or after the biopolymer has been dispersed in a solution but before the alkoxide has been added, or alternatively, after the biopolymer and alkoxide have been added to the solution. One or more functional additives may be added at different stages of making the sol. The functional additives may be used to adjust the properties of the sol in the same manner as they may be used to adjust the properties of any wetting agent as described herein, e.g. to control viscosity, density or rheology of the sols; to make the sol suitable for UV, visible or IR curing; and/or may be used to add additional functionality to a coating prepared using the sol, e.g. colour, pH sensitivity, conductivity, fluorescence. The functional additives used will vary depending on the intended use of the sol. Suitable functional additives include photoinitiators, resins, oils, dyes (including pH sensitive dyes, fluorescent dyes and food grade organic colours), salts, surfactants, composite particles, mineral or other inorganic particles (including carbonates, carbides, oxides, hydroxides, nitrates, bromides, and the like), anti-microbial agents, biopolymers, and metal particles (including alloys and particles comprising one or more metals and one or more additional non-metal components). The sols may be also formed without the presence of any additives, biopolymers or catalysts. More particularly, sols may be wholly or substantially free of additives and/or biopolymers and/or catalysts during formation and/or use.

[0021] Sols, when used in the method of the present invention, may be used without being modified before use. Thus, the moulded products prepared using sols in accordance with the method of the present invention may be prepared from air-laid pulp and a sol without the sol being modified before use. For example, a water-resistant or water-impermeable product may be prepared from an air-laid pulp using a sol that is substantially free of additives, i.e. the water resistant or water impermeable moulded product is prepared by applying the sol to an air-laid pulp in the absence of any functional additives. Alternatively, the sols which may be used in the method of the present invention may be modified before use. For example, sols, when used in the methods of the present invention, may be modified by diluting a sol with a solvent, combining a sol with functional additives or both diluting a sol with a solvent and combining a sol with functional additives. Suitable solvents for use in diluting the sol include the solvent used to disperse the alkoxide when forming a sol (sometimes referred to as the sol solvent), other solvents that are miscible with the sol solvent, or combinations thereof. The functional additives may be used to adjust the properties of a sol such as the rheology, density, or viscosity of the sol and/or may be used to add additional functionality to a coating prepared using a sol. The functional additives used will vary depending on the intended use of the sol and suitable functional additives include photoinitiators, resins, oils, dyes (including pH sensitive dyes, fluorescent dyes and food grade organic colours), salts, anti-microbial agents, mineral or other inorganic particles, surfactants, biopolymers, composite particles and/or metal particles, or any combination thereof.

[0022] Sols are generally stable by definition. A sol may therefore be formed some time prior to use of the sol as part of the methods described herein. For example, the sol may be formed and stored for a period of up to 1 hour, up to 1 day, up to 1 week, up to 1 year, up to 10 years, or more prior to use of the sol in the methods of the present invention. However, the sol may also be formed immediately prior, less than 2 seconds prior, less than 15 seconds prior, less than 30 seconds prior, less than a minute prior, or less than an hour prior to use of the sol. The sol may be formed in geographical proximity to the location at which it will be used. Alternatively, the sol may be formed distant from the site at which the sol is to be used and then transported to that site. In an example, the sol may be formed at a manufacturing site in an on-line process a matter of seconds before it is applied to an air-laid pulp. In another example, the sol may be formed in an independent manufacturing facility and then transported by road, rail, air, sea, pipeline or equivalent to a geographically distinct site where the sol is applied to an air-laid pulp. More generally, sols may be formed distinct from the pulp to which the sol is to ultimately be applied, where appropriate. In such an example, the sol and the air-laid pulp to which the sol is to be applied will be brought together following formation of the sol. Alternatively, a sol may be formed around an air-laid pulp to which the sol is to be applied such that the formed sol coats the air-laid pulp and/or permeates the pulp immediately, substantially immediately, or shortly after formation.

[0023] Sols or other wetting agents that may be used in the method of the present invention may optionally include one or more biopolymers. The one or more biopolymers, where present, may include one or more polysaccharides. For example, the biopolymer may comprise starch-based polymer, hemi-cellulose-based polymer, cellulose-based polymer, lignin-based polymer, chitosan- based polymer, any other suitable biopolymer or modified biopolymer, and any combination thereof. The sol may additionally, or alternatively, comprise one or more flours derived from natural materials. Suitable flours may include oat flour, barley flour, rye flour, wheat flour, rice flour, bamboo flour, lentil flour, chickpea flour, pea flour, corn flour, or any combination thereof. The use of a biopolymer in the sols may act as a natural surfactant forming networks with negatively charged species such as alkoxides, where present.

[0024] Starches suitable for use in sols which may be used with the methods of the present invention include positively charged plant-derived starches or the synthetic and derivative equivalents thereof such as cationic starch. Other starches such as anionic or neutral starches may also be used depending on the desired properties of the sol. In some examples, starches and other polysaccharides may be combined in a single sol, which may help optimise the functionalities of the sol. Cationic starch suitable for use in sols which may be used in the methods of the present invention includes primary, secondary, tertiary and quaternary cationic starch. Quaternary ammonium type starch is cationic in both high pH and low pH solutions, whereas primary, secondary and tertiary ammonium type starch is only cationic in low pH solutions. Hence different types of cationic starch may be suited to different applications. Sols that include one or more starches or cationic starches may be water-impermeable and/or oil-impermeable and/or vapour-impermeable and/or gas-impermeable and/or anti-microbial and/or hydrophobic and/or oleophobic and/or anti-fouling and/or anti-biofouling and/or stain resistant and/or antireflective. In particular, quaternary ammonium type starch has been found to be particular effective at imparting anti-microbial properties to the sol. In general terms, anti-microbial sols may be anti-bacterial and/or anti-fungal and/or anti-viral and/or anti-algae and/or anti-parasitic. Sols including starches have also been shown to be effective in preventing the growth of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus hirae.

[0025] Flours suitable for use in the sols which may be used in the methods of the present invention include positively or negatively charged plant-derived flours or the synthetic and derivative equivalents thereof. Other flours such as neutral flours may also be used depending on the desired properties of the sol. Different flours may be combined in a single sol, which may help optimise the functionalities of the sol. Additionally, or alternatively, the flour may be combined with one or more additional polysaccharides depending upon the desired properties and functionality of the sol. In general, plant-derived flours are the powdered form of plant material such as wheat. Flours comprise a range of constituent ingredients including proteins, fats, sugars, starches, amino acids, vitamins and trace elements. The composition of a flour depends upon the composition of the material from which it was sourced. For example, an oat flour may contain a greater proportion of cellulose than a wheat flour. Example compositions of various plant flours that may be used in sols that may be used in the methods of the present invention are provided in Table 1. The flour used in sols which may be used in the methods the present invention may be selected from oat flour, barley flour, rye flour, wheat flour, buckwheat flour, rice flour, bamboo flour, lentil flour, chickpea flour, green pea flour, corn flour, and combinations thereof. Other plant- derived flours including starch, hemi-cellulose, cellulose, lignin or other polysaccharides may also be used.

Table 1 Example compositions of flours derived from various plant materials

[0026] In general, plant-derived flours that may be used in the sols which may be used in the method of the present invention may comprise 5 to 85 wt% starch, optionally in combination with 0 to 30 wt% hemi-cellulose, 0 to 50 wt% cellulose, 0 to 25 wt% lignin, 0 to 35 wt% protein and 0 to 25 wt% ash. Other suitable flours may comprise 20 to 80 wt% starch, optionally in combination with 5 to 30 wt% hemi-cellulose, 0 to 50 wt% cellulose, 0 to 25 wt% lignin, 0 to 35 wt% protein and 0 to 25 wt% ash. Yet other suitable flours may comprise 45 to 80 wt% starch, optionally in combination with 5 to 30 wt% hemi-cellulose, 0 to 50 wt% cellulose, 0 to 25 wt% lignin, 0 to 35 wt% protein and 0 to 25 wt% ash. A further flour that may be suitable for the sols of the present invention may comprise 45 to 70 wt% starch, optionally in combination with 5 to 15 wt% hemicellulose, 0 to 10 wt% cellulose, 0 to 7 wt% lignin, 10 to 15 wt% protein and 0 to 5 wt% ash. In other examples, a suitable flour may comprise 20 to 70 wt% starch, optionally in combination with 0 to 15 wt% hemi-cellulose, 0 to 10 wt% cellulose, 0 to 10 wt% lignin, 5 to 35 wt% protein and 0 to 25 wt% ash. Additionally or alternatively, a suitable flour may comprise 45 to 70 wt% starch, optionally in combination with 5 to 15 wt% hemi-cellulose, 0 to 10 wt% cellulose, 0 to 10 wt% lignin, 5 to 15 wt% protein and 0 to 10 wt% ash. Still further a flour that may be suitable for the sols of the present invention may comprise 45 to 85 wt% starch, optionally in combination with 0 to 15 wt% hemi-cellulose, 0 to 10 wt% cellulose, 0 to 10 wt% lignin, 0 to 15 wt% protein and 0 to 10 wt% ash.

[0027] The wetting agents described herein may be applied to any suitable air-laid pulp material prior to hot-pressing of the intermediate pulp thus formed to form a moulded product. For the avoidance of doubt, the term ‘air-laid pulp’ in the contents of the methods of the present invention refers to the pulp formed following the carrying, laying, shaping, and/or spinning of fibrous material in a gaseous medium. As previously described herein, one or more sizing agents, binders or other additives may be used to treat the fibres prior to or during the laying process. However, as also described herein, such sizing agents, binders, and/or other additives may also be absent. In an example, the air-laid pulp may be formed at least partially from wood fibre. In another example, the air-laid pulp may be formed from non-wood plant fibres. In a yet further example, the air-laid pulp may be formed at least partially from synthetic fibres. The air-laid pulp may therefore comprise plant fibres, wood fibres, natural fibres, any other suitable fibres, or any combination thereof. The air-laid pulp may be air-laid pulp, fluff pulp, recycled pulp, any other suitable category and/or classification of pulp considered to constitute air-laid pulp, or any combination thereof. The air-laid pulp may comprise, consist, or consist essentially of wood-based fibres. The air-laid pulp may comprise, consist, or consist essentially of plant-based and/or natural-derived fibrous material. The air-laid pulp may be free, or substantially free, from synthetic fibres. The air-laid pulp may be free, or substantially free, from textile fibres. The use of air-laid pulp is considered advantageous as air-laid pulp does not require the quantities of water, disinfectant, and other chemicals commonly associated with the production and/or processing of wet pulp. The use of air-laid pulp in preference to wet pulp is therefore environmentally beneficial. Where a wetting agent with particular functionality is used, the method may provide further advantages depending upon the wetting agents used. In an example, the sols disclosed herein are generally antimicrobial/antibacterial and so may allow for a further reduction or the elimination of disinfectant or similar agents in the production of a product. Antimicrobial and antibacterial products that do not require the use of additional or specific antimicrobial or antibacterial agents may be advantageous in applications in which a product is to be used in the food or drink industry where microbial growth is undesirable but some alternative disinfectant agents themselves may pose health risks to humans. Air-laid pulp also typically has a more open pore-structure than the equivalent wet pulp or wet-laid pulp. The more open pore-structure may allow the wetting agent to better penetrate the structure of the air-laid pulp such that the wetting agent may better treat a greater proportion of the air-laid pulp structure and any functional additives and/or sols forming part of the wetting agent may be more thoroughly dispersed throughout the material. Where the air-laid pulp is a recycled pulp, the recycled air-laid pulp may be formed from or include material from one or more products that had previously been manufactured using the methods described herein. Where the recycled air-laid pulp includes material from a product formed using the methods of the present invention, the recycled air-laid pulp may retain at least a portion of the functional characteristics and/or components applied to the air-laid pulp during manufacture of the now recycled product. Where this applies, the recycled air-laid pulp may retain at least some of the functionality imparted by a functional additive and/or sol forming part of the wetting agent during its original manufacture. It may therefore be possible to impart a desired property to a product formed from recycled air-laid pulp by reducing the amount of functional additive and/or sol applied to the air-laid pulp in proportion to the amount of functional additive and/or sol residual in the recycled material.

[0028] The method includes the application of a wetting agent to an air-laid pulp. The amount of wetting applied to the pulp will depend upon the wetting agent being used, the material forming the air-laid pulp to which the wetting agent is to be applied, and the desired characteristics of the intermediate pulp and/or product formed following application of the wetting agent to the air-laid pulp. In an example, 5 ml of wetting agent may be applied to a 10 cm² surface of an air-laid pulp. In another example, 100 ml of wetting agent may be applied to a 10 cm². In a yet further example, 2 litres of wetting agent may be applied to a 1 m² surface area of air-laid pulp. The quantity of wetting agent applied to the air-laid pulp may be determined based upon the dry weight of the airlaid pulp. (For the avoidance of doubt, the term ‘dry weight’ as used herein refers to the weight of the air-laid pulp as supplied, not the weight of the air-laid pulp after it has been dried at a sufficient temperature to remove any moisture, e.g. water, inherently present within the structure of the airlaid pulp.) For example, wetting agent with a weight equivalent to, or in excess of about 10%, about 12%, about 14%, about 16%, about 18%, about 20%, about 22%, about 24%, about 26%, about 28%, about 30%, about 35%, about 40%, about 45%, about 50%, about 60%, about 70%, about 80%, about 90%, about 100%, about 125%, about 150%, about 175% or about 200% of the dry weight of the air-laid pulp may be added. Therefore, in such examples, an amount of wetting agent in a range of between about 10% and about 200% of the dry weight of the air-laid pulp may be added. In other examples, an amount of wetting agent in a range of about 10% to about 190%, about 10% to about 180%, about 10% to about 170%, about 10% to about 160%, about 10% to about 150%, about 10% to about 140%, about 10% to about 130%, about 10% to about 120%, about 10% to about 110%, about 10% to about 100%, about 10% to about 90%, about 10% to about 80%, about 10% to about 70%, about 10% to about 60%, about 10% to about 50%, about 10% to about 40%, about 10% to about 30%, about 10% to about 20%, about 20% to about 200%, about 20% to about 190%, about 20% to about 180%, about 20% to about 170%, about 20% to about 160%, about 20% to about 150%, about 20% to about 140%, about 20% to about 130%, about 20% to about 120%, about 20% to about 110%, about 20% to about 100%, about 20% to about 90%, about 20% to about 80%, about 20% to about 70%, about 20% to about 60%, about 20% to about 50%, about 20% to about 40%, about 20% to about 30%, about 30% to about 200%, about 30% to about 200%, about 30% to about 190%, about 30% to about 180%, about 30% to about 170%, about 30% to about 160%, about 30% to about 150%, about 30% to about 140%, about 30% to about 130%, about 30% to about 120%, about 30% to about 110%, about 30% to about 100%, about 30% to about 90%, about 30% to about 80%, about 30% to about 70%, about 30% to about 60%, about 30% to about 50%, about 30% to about 40%, about 40% to about 200%, about 40% to about 190%, about 40% to about 180%, about 40% to about 170%, about 40% to about 160%, about 40% to about 150%, about 40% to about 140%, about 40% to about 130%, about 40% to about 120%, about 40% to about 110%, about 40% to about 100%, about 40% to about 90%, about 40% to about 80%, about 40% to about 70%, about 40% to about 60%, about 40% to about 50%, about 500% to about 200%, about 50% to about 190%, about 50% to about 180%, about 50% to about 170%, about 50% to about 160%, about 50% to about 150%, about 50% to about 140%, about 50% to about 130%, about 50% to about 120%, about 50% to about 110%, about 50% to about 100%, about 50% to about 90%, about 50% to about 80%, about 50% to about 70%, about 50% to about 60%, about 60% to about 200%, about 60% to about 190%, about 60% to about 180%, about 60% to about 170%, about 60% to about 160%, about 60% to about 150%, about 60% to about 140%, about 60% to about 130%, about 60% to about 120%, about 60% to about 110%, about 60% to about 100%, about 60% to about 90%, about 60% to about 80%, or about 60% to about 70% of the dry weight of the air-laid pulp may be added. However, amounts of wetting agent of below about 10% may also be used with the methods and processes described herein. For example, an amount of wetting agent of up to about 8% of the dry weight of the air-laid pulp may be added. The quantity of wetting agent applied to the air-laid pulp will vary depending on: the characteristics of the air-laid pulp such as thickness, structure, pore volume, surface area, etc; the mould or apparatus used to hot-press the intermediate pulp to form a moulded product; the nature and/or chemistry of the fibres from which the air-laid pulp was formed; and/or the presence and type of any sizing agents, binders or other additives used in the manufacturing of the air-laid pulp. For example, hot-pressing an intermediate pulp formed from air-laid pulp that comprises a binder may cause at least some of the binder to melt and act similarly to the wetting agent, or may cause the binder to dissolve within the wetting agent. In such an example, the method of the present invention may require less wetting agent to be applied to achieve the same technical effect in comparison with the method as used to form a moulded product from an air-laid pulp to form an intermediate pulp that did not comprise a binder. The skilled person, with the benefit of this disclosure, will be able to determine a suitable proportion of wetting agent to be applied in a particular process or method. In the methods described herein, the term ‘intermediate pulp’ is used to describe a pulp material to which a wetting agent has been applied. The wetting agent may be applied to the pulp by any suitable means including, but not limited to, brushing, spraying, spray drying, rolling, dropping, injecting, transferring, submersion, immersion, mixing, spreading, blading, padding, or any combination thereof. In an example, it may be advantageous to apply the wetting agent to the air-laid pulp by spraying techniques. In another example, it may be advantageous to apply the wetting agent to the air-laid pulp by one or more roller-based techniques. In examples where the air-laid pulp is free, or substantially free, of water then application of 100% wetting agent by dry weight will result in an intermediate pulp of approximately 50% wetting agent and 50% pulp. Similarly, in examples where 200% wetting agent by weight of dry air-laid pulp is applied, the intermediate pulp will include approximately 33% by weight of pulp and approximately 66% wetting agent. Even if a mass of wetting agent in excess of the mass of dry material is applied, the total wetting agent content of the intermediate pulp will remain below the 90% or more water present in wet pulp applications.

[0029] Applying a wetting agent, or a wetting agent including a functional additive, to pulp may allow different volumes or masses of air-laid pulp to adhere together. Applying a wetting agent or a wetting agent including one or more functional additives to a surface of an air-laid pulp, and then contacting the surface to which the wetting agents has been applied with another surface of a different volume or mass of air-laid pulp may allow the volumes or masses of air-laid pulp to adhere together. In an example, applying a wetting agent or a wetting agent including a functional additive, such as a sol, to a thin sheet of air-laid pulp prior to contact the sheet of air-laid pulp with a second sheet of air-laid pulp may allow the two sheets of air-laid pulp to adhere together prior to further processing and/or formation of a moulded product.

[0030] The method of the present invention comprises hot-pressing the intermediate pulp to which a wetting agent has been applied to form a moulded product. A hot-press process in this context involves the application of pressure to a material in the presence of heat such that the material being pressed is provided heat and/or thermal energy beyond that imparted solely as a result of the mechanical force involved in the compression. In some examples, the hot-press process may involve actively heating the material being pressed. For the avoidance of doubt, ‘actively heating’ a material involves the intentional application of heat and/or thermal energy to raise the temperature of the material. This may be achieved by flowing a heated fluid through one or more conduits present in the hot-press apparatus, performing the hot-press in a heated room or atmosphere, or any other suitable means of heating. In other examples, the hot-press method may be performed by heating the press apparatus, mould, or the like using an oven or similar means before using the press apparatus or mould in the methods described herein. The hot-press process, hot-press apparatus, or material subjected to the hot-press process may therefore be at a temperature of greater than 100 °C or greater than 150 °C, optionally about 105 °C, about 110 °C, about 115 °C, about 120 °C, about 125°C, about 130 °C, about 135 °C, about 140 °C, about 145 °C, about 150 °C, about 155 °C, about 160 °C, about 165 °C, about 170 °C, about 175 °C, about 180 °C, about 185 °C, about 190 °C, about 195 °C, about 200 °C, about 205 °C, about 210 °C, about 215 °C, about 220 °C, about 225°C, about 230 °C, about 235 °C, about 240 °C, about 245 °C, about 250 °C, about 255 °C, about 260 °C, about 265 °C, about 270 °C, about 275 °C, about 280 °C, about 285 °C, about 290 °C, about 295 °C and/or about 300 °C. The hot-press process, hot-press apparatus, or material subjected to the hot-press process may be at a range of temperatures with a lower range limit and upper range limit of any temperature described herein in relation to the hot-press process. For example, the skilled person, with the benefit of this disclosure, will understand that a temperature range of about 100 °C to about 300 °C, about 135 °C to about 225 °C, or any other temperature range defined by hot-press temperatures recited herein may be used. It may be advantageous to carry out the hot-press method at a temperature below the boiling point of one or more components of the wetting agent and/or pulp. As will be described in more detail below, it may be particularly advantageous to carry out the hot-press method at a temperature below the boiling point of each and every component of the wetting agent and/or pulp.

[0031] In contrast, a cold-press process in this context involves the application of pressure to a material without heating the material or applying additional energy to the material beyond that resulting from the mechanical force involved in the compression. In examples including additionally cold-pressing the air-laid pulp, intermediate pulp, or moulded product, the additional cold-press method step may involve actively cooling the material being pressed. For the avoidance of doubt, ‘actively cooling’ a material involves the intentional removal of heat and/or thermal energy to lower or reduce the temperature of the material. This may be achieved by flowing a coolant through one or more conduits present in a cold-press apparatus, performing the additional cold-press in a cold room or atmosphere, or any other suitable means of cooling. In other examples including additionally cold-pressing the air-laid pulp, intermediate pulp, or moulded product, the additional cold-press method step may be performed at room temperature or ambient temperature suffice that no steps are taken to increase the temperature of the material being pressed beyond that which would normally be experienced by pressing such material in an ambient temperature and pressure environment. An additional cold-press method step, coldpress apparatus, or material subjected to an additional cold-press method step may therefore be at a temperature of less than about -10 °C, less than about -5 °C, less than about 0 °C, less than about 5 °C, less than about 10 °C, less than about 15 °C, less than about 20 °C, less than about 25 °C, less than about 30 °C, less than about 35 °C, less than about 40 °C, less than about 45 °C, less than about 50 °C, less than about 60 °C, less than about 70 °C, less than about 80 °C, less than about 90 °C, and/or less than about 100 °C. In general, any examples of the methods of the present invention including an additional cold-press method step may be carried out such that the air-laid pulp, intermediate pulp, and/or wetting agent are not heated above, or used at a temperature of, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 70 °C, 80 °C, 90 °C, and/or 100 °C during the cold-press method step. Notably, it may be advantageous to carry out any additional coldpress method step at a temperature in excess of the freezing point of one or more components of the wetting agent. In an example where the wetting agent includes water, an additional coldpress method step may be carried out at temperatures in excess of 0 °C but less than 25 °C. In an example, an additional cold-pressing of the intermediate pulp is carried out at a temperature less than 100 °C. In another example, an additional cold-pressing of the intermediate pulp is carried out at a temperature of less than 50 °C. Equally, it may be advantageous to carry out any additional cold-press method at a temperature below the boiling point of one or more components of the wetting agent and/or pulp. As will be described in more detail below, it may be particularly advantageous to carry out any additional cold-press method step at a temperature below the boiling point of each and every component of the wetting agent and/or pulp.

[0032] Both hot- and cold- press processes described herein involve the application of force and pressure to the intermediate pulp formed following application of a wetting agent. Pressing processes will therefore cause any wetting agent and/or other fluid present in the intermediate pulp to be forced out of the intermediate pulp as the intermediate pulp mass is compressed. For example, any residual wetting agent may be forced out of the intermediate pulp following application of pressure. In hot-press processes, and particularly those carried out at temperatures in excess of the boiling point of one or more components of the wetting agent and/or intermediate pulp, gases may form which will also be forced out of the intermediate pulp as pressure and heat is applied to said pulp. For the avoidance of doubt, the formation of intermediate pulp from air-laid pulp will often cause the intermediate pulp to contain air or other gases from the atmosphere in which the air-laid pulp and/or intermediate pulp has been resident. Such gases may also be expelled from the pulp when subjected to a hot- or cold-press process. The removal or expelling of fluid from the intermediate pulp during a press process may risk the quality of the moulded product. For example, concentration of the expelled fluid at the surface of the moulded product may result in localised buildup of pressure which can cause damage or tearing on the surface of the moulded product. Additionally, or alternatively, concentration of the expelled fluid in one or more portions of the internal structure of the intermediate pulp may cause the concentrated fluid to escape the internal structure of the intermediate pulp through the path of least resistance, rupturing the structure of the moulded product as the fluid is expelled during the pressing of the intermediate pulp. To mitigate and/or alleviate such issues, it may be advantageous to include to include one or more fluid escape elements such as holes, vents, apertures, flow passages, conduits, pipes, pathways, or the like in the mould, plate, associated apparatus, or other surface used to hot-press and/or cold-press the air-laid pulp, intermediate pulp, or moulded product such that fluid, optionally wetting agent in the form of vapour and/or liquid, can escape. For example, where the hot-press method is carried out at temperatures above the boiling point of one or more components of the wetting agent and/or pulp, the mould, press, or other apparatus used to form the moulded intermediate pulp shape may include one or more fluid escape elements configured to allow fluid (e.g. wetting agent in the form of vapour and/or liquid) to escape, such that the fluid exits the mould, press, or other apparatus without damaging a moulded product being formed from an intermediate pulp. In an example, the mould may include multiple parts, with some parts used in the shaping of the moulded product and others providing additional or alternative functions. The holes, channels, fluid passages, apertures, or fluid escape elements intended to allow fluid to escape from the pressing process may be included in any suitable part. For example, the one or more fluid escape elements may be included in the cavity portions of the main plates used to shape the moulded product. Additionally, or alternatively, the one or more fluid escape elements or other fluid directing components may be present in auxiliary parts of the apparatus or in portions of the apparatus not directly involved in the formation of the moulded shape. In such examples, the one or more parts of the mould not involved in the formation of the moulded shape may be used to vent, channel, direct, release, and or otherwise remove moisture and/or vapour from the mould during or after the formation of the moulded shape. In an example, a mould comprising two main plates may include a third part in between the main plates which has a structure that provides an exit path for liquid and/or vapour. The application of pressure and/or temperature may result in the expansion of material and/or a change in phase of one or more components present in the mould. To prevent failure of the mould and/or damage to the product, intermediate product and/or moulded shape, or other undesirable consequences it may be beneficial to provide a means for any excess material, fluid, or the like to exit the mould in a controlled manner. Such means may include one or more fluid escape elements, optionally in the form of a hole, vent, aperture, flow passage, conduit, pipe, pathway, or the like. In another example, where the hot-press does not elevate the temperature of the intermediate product above the boiling point of one or more components of the wetting agent, then the mould or press apparatus may include one or more fluid escape elements to allow liquid liberated from the airlaid pulp upon pressing (e.g. wetting agent in the form of liquid) to escape, such that the fluid exits the mould, press, or other apparatus without damaging a moulded product being formed from an intermediate pulp. In one particular example, liquid may escape during the pressing and/or moulding process at the interface between two portions of the mould or press apparatus. The inclusion of one or more fluid escape elements may improve the quality and/or consistency of the moulded product. Thus the one or more fluid escape elements are intended to allow fluid to exit a mould or press apparatus during a hot-press method step, they are not intended to allow a moulded product to be removed from a mould or press apparatus after a hot-press method step has been completed. In some known processes, holes, vents, conduits, or the like in a mould are used to direct air or gases into the mould to aid in the removal a product from said mould. In the methods and apparatus of the present disclosure, the one or more fluid escape elements may not be used for the delivery of air or gases into the mould while the moulded product remains in the mould as any fluid that has left the moulding process via the one or more fluid escape elements will be forcibly returned to the moulded product which may cause damage to the surface of the material. Therefore, the one or more fluid escape elements such as holes, channels, pathways, conduits, apertures, or other structures used to channel, direct, and/or otherwise remove fluid from the mould may not be connected to an air or gas delivery system that delivers gas into the mould at the least when the moulded product remains in the mould. Fluids, liquids or gases such as air may be used to clean, unblock, or unclog the fluid escape elements when the moulded product is no longer in the mould as material, fibres, particles, or the like may obstruct the fluid escape elements through use.

[0033] The number of fluid escape elements provided within a mould or press apparatus and the size, diameter, or proportions of those fluid escape elements may be adjusted to reduce the risk of damage to the intermediate pulp when it is pressed. If a mould or apparatus includes too few fluid escape elements, or fluid escape elements that are too small in size, then the intermediate pulp may be torn during formation of the moulded product due to increases in pressure and/or an escalation in the forces involved in the dynamics of the fluid moving in, around, and through the intermediate pulp, apparatus, and/or fluid escape elements. However, if a mould or apparatus includes too many fluid escape elements, or fluid escape elements that are too large in size, then the surface characteristics of the moulded product may be detrimentally affected. Furthermore, the number and size of the fluid escape elements may vary depending on the location of the fluid escape elements within the mould or apparatus and the size and shape of the mould or apparatus. Fluid escape elements are typically located in areas of a mould or apparatus where a significant amount of wetting agent would be expected to congregate since that will reduce localised increases in pressure. For example, in a dome-shaped mould, a hole may be included at the top and centre of the mould (where the dome is viewed as pointing upwards) as this is where localised pressure and wetting agent content may be expected to be highest during or immediately following pressing. Alternatively, in a flat plate mould, the holes may be more evenly distributed, optionally with a higher concentration of holes towards the centre of the plate if the plate is large. A flat shape may be expected to result in fewer localised increases in pressure but may require liquid present towards the middle of the plate to be allowed to leave the mould more rapidly and/or in greater volume than will be required towards the periphery of the plate. The shape of the mould will also influence the number and size of the fluid escape elements since shapes that include paths or other topography that allows wetting agent to be channelled may inherently reduce the risk of damage to the intermediate pulp. Furthermore, it may be advantageous for a mould or apparatus to comprise fluid escape elements of varied size, shape, type, cross-section, topography, and/or design.

[0034] The hot-press method step and any additional hot- or cold-press method steps included in the method of the present invention may be carried out at any suitable pressure. In general, the hot-press method step and any additional hot- or cold-press method steps included in the methods of the present invention may be carried out at a reduced or lower pressure than would be required to process wet pulp material, or pulp materials including thermoplastics or hydrocarbon-based polymers. The hot-press method step(s) may apply pressures of at least or about 1000 kg/m², at least or about 1500 kg/m², at least or about 2000 kg/m², at least or about 2500 kg/m², at least or about 3000 kg/m², at least or about 4000 kg/m², at least or about 5000 kg/m² or at least or about 6000 kg/m². The hot-press method step(s) may be carried out across a range of pressures. For example, the method may carry out a hot-press process across a pressure range of about 1000 kg/m² to about 5000 kg/m². A pressure range starting from, and extending to, any suitable pressure disclosed herein may be used as a pressure range for a hot-press process. Any additional cold-press method step may apply pressures of less than 25000 kg/m², less than 5000 kg/m², less than 4000 kg/m², less than 3000 kg/m², less than 2000 kg/m², less than 1000 kg/m², less than 500 kg/m², less than 300 kg/m², less than 250 kg/m², less than 200 kg/m², less than 150 kg/m², less than 100 kg/m², less than 50 kg/m², less than 40 kg/m², less than 30 kg/m², less than 20 kg/m², less than 10 kg/m², or any other suitable pressure to the intermediate pulp to form the moulded product. For example, the hot-press method step and any additional cold-press method step may apply pressures of about 1000 kg/m², about 2000 kg/m², about 3000 kg/m², about 4000 kg/m², about 5000 kg/m², about 6000 kg/m², about 7000 kg/m², about 8000 kg/m², about 9000 kg/m², about 10000 kg/m², or more. In one particular example, a pressure of 6000 kg/m² may be used. In another particular example, a pressure of 3000 kg/m² may be used. Hot-pressing the intermediate pulp, and any additional cold-pressing, may comprise pressing the intermediate pulp into at least one mould, pressing the intermediate pulp between at least one plate and at least one other surface, or any combination thereof. The product may therefore be formed or otherwise shaped using one or more moulding shapes, templates or casts. The term ‘mould’ is used herein to generally define a component of an apparatus including a shaped recess portion into which the intermediate pulp may be directed to shape the intermediate pulp. Moulds typically provide an entry aperture or apertures for the intermediate pulp to enter the shaped recess on a single side of the recess such that the three-dimensional shape of the recess is completed when the mould is brought together with another mould or surface during the pressing process. However, some moulds may allow entry of the intermediate pulp into the shaped recess from multiple sides or portions of the recess. The exact configuration of a mould will depend upon the characteristics and requirements of the moulded product being produced. The skilled person, with the benefit of this disclosure, will be able to identify a suitable mould for a specific product. Hot-pressing the intermediate pulp, and any additional cold-pressing, may therefore comprise passing the material through an aperture wherein the aperture is formed from at least one roller comprising one or more shaped mould depressions and at least one other surface. For example, hot-pressing an intermediate pulp, and any additional cold-pressing, may involve passing the intermediate pulp between two rollers wherein at least one roller comprises one or more shaped mould depressions such that pressure is applied to the intermediate pulp and a moulded product is formed. In another example, hot-pressing the intermediate pulp, and any additional cold-pressing, may involve placing the intermediate pulp into a mould and then pressing the intermediate pulp with a plate or counter-shape such that it occupies the shape of the mould. In one example, the intermediate pulp may be placed in a first positive or negative mould and then a second corresponding positive or negative mould shape is applied to shape the intermediate pulp. In such an example, the first mould and second mould may include a positive mould and a negative mould. Pressure may be applied using another mould portion, pressure plate, or other suitable pressure application means. Returning to the example of the positive and negative mould, either the positive or negative mould may apply pressure by pressing or being pressed upon the intermediate pulp residing in the other positive or negative mould. Moulds or mould apparatus, in general, may include one or more fluid escape elements such as drainage channels, conduits, pathways, or the like, to allow any excess fluid to be drained from the intermediate pulp when pressure is applied during the cold-press process. The hot-press method step method step and any additional cold-press method step may comprise applying pressure to the intermediate pulp for any suitable period of time. Advantageously, the method of the present invention allows a moulded product to be formed using pressure applied to the intermediate pulp for only a short amount of time. The pressure may be applied to the intermediate pulp for a period of less than or equal to about 20 seconds, less than or equal to about 15 seconds, less than or equal to about 10 seconds, less than or equal to about 8 seconds, less than or equal to about 6 seconds, less than or equal to about 5 seconds, less than or equal to about 4 seconds, less than or equal to about 3 seconds, less than or equal to about 2 seconds, less than or equal to about 1 second, less than or equal to about half a second, or less than or equal to about a quarter of a second, optionally for a period of about 20 seconds, about 15 seconds, about 10 seconds, about 9 seconds, about 8 seconds, about 7 seconds, about 6 seconds, about 5 seconds, about 4 seconds, about 3 seconds, about 2 seconds, about one second, about half a second, or about a quarter of a second. For the avoidance of doubt, the application of pressure in this context may refer to the application of pressure to all or part of a given volume or mass of intermediate pulp. In an example, pressure may be applied to the intermediate pulp for less than about 1 second. In another example, pressure may be applied to the intermediate pulp for less than about 0.5 seconds. In one particular example of a hot-press method step, the intermediate pulp may be processed into a moulded product using a reel-to-reel process, a reel-to-sheet process, a sheet-to-reel process, or a sheet-to-sheet process. In sheet- to-reel or sheet-to-sheet processes, sheets of raw pulp material are fed into the apparatus and processed before being either fed to a reel system or removed from the apparatus in the form of a moulded product sheet. In processes where a reel is formed, batch and/or non-continuous processes may form a reel of moulded product which may then be used in one or more continuous or intermittently continuous processes. In reel-to-reel, or reel-to-sheet processes, the intermediate pulp may form one continuous mass which is fed through rollers comprising one or more shaped mould depressions at high speed. The pressure used in such an arrangement need only be sufficient to form the moulded shape. The application of wetting agent prior to pressing the intermediate pulp ensures that the intermediate pulp is suitably malleable for high-speed processing while the resulting minimal contact time with the press apparatus and relatively low pressure prevent the intermediate pulp fibres from becoming damaged. In addition, a relatively low quantity of wetting agent may be applied to air-laid pulp that is intended to be processed into a moulded product using a reel-to-reel process, a reel-to-sheet process, a sheet-to-reel process, or a sheet-to-sheet process. It may be particularly advantageous to utilise a reel-to-reel process as such processes allow continuous, or semi-continuous, air-laid pulp material to be processed at speed to form further continuous, or semi-continuous, moulded product material. Such processes allow the processing of large quantities of material at speeds and throughput rates which may be greater than achievable with ‘sheet’ processes where sheets must either be loaded or removed from the start or end of the process, respectively. Furthermore, the use of roller-type moulds with reel-to-reel processes may allow pressure to be applied to any given portion of intermediate pulp material for a relatively short period of time such as less than or equal to about 1 second, less than or equal to about 0.5 seconds, or less than or equal to about 0.25 seconds, which may reduce the risk of damaging the intermediate pulp material and/or moulded product through excessive or prolonged application of pressure. The use of two rollers, or the like to apply pressure to the intermediate pulp also provides a smaller relative area in which pressure is applied to the intermediate pulp when compared to batch processes using sheets and presses. The use of such reels, rollers, or the like to apply pressure to the intermediate pulp in only a small surface area portion of the intermediate pulp being fed to the roller may allow for the fluids, gases, and/or liquids in the intermediate pulp to escape from the roller press along the sides of one or both of the rollers without risking damage to the intermediate pulp and/or moulded product. For example, a roller contact area width of less than 1 cm, about 1 cm, about 1 .5 cm, or up to about 2 cm may allow for the escape of fluid along the sides of one or both rollers. In such examples, rollers and moulds may not require one or more fluid escape elements to prevent fluid escaping the pulp from damaging the moulded product. Where a larger contact area width is applied, rollers and moulds may still include fluid escape elements as described herein to allow fluid to escape the intermediate pulp and/or moulded product through the fluid escape elements in the mould, roller, or the like. The combination of contact pressure for a short period of time in addition to the use of the small contact area provided by roller moulds in a reel-to-reel process may also allow fluid escaping the intermediate pulp and/or moulded product to be carried away from where pressure is applied to the intermediate pulp.

[0035] Hot-pressing the intermediate pulp forms a moulded product. The term ‘product’ as used herein is intended to include intermediate, work in progress and unfinished products and their components in addition to otherwise finished goods and articles. For example, a moulded product formed from the hot- or cold-pressing of intermediate pulp may be a finished article such as a paper shape, a ready-to-use cardboard pot, or the like. In other examples, the product may be an intermediate component which is used to form or assemble a larger product. The product may be a water resistant or water impermeable product. Where the product is a water resistant or water impermeable product, the water resistance or water impermeability may be imparted to the product by hot- or cold-pressing an intermediate pulp to which an impermeability-promoting functional additive has been applied. A sol used as at least part of a wetting agents may promote formation of a water or gas resistant or water or gas impermeable product. The methods of the present invention may therefore be used to form products such as packaging materials. In one example, the mould, press, or template may be shaped such that the intermediate pulp is formed into fibre-based bubble wrap which includes raised and lowered portions with the raised portions encasing a hollow interior to replicate the function standard bubble wrap. In another example, the mould, press, or template may be shaped such that the intermediate pulp is formed into spherical, hemi-spherical, substantially spherical, and/or substantially hemi-spherical shapes. The product formed by the methods described herein may therefore include a water resistant or water impermeable fibre-based packing material. The water resistant or water impermeable fibre-based packing material may be a water resistant or water impermeable fibre-based bubble wrap. Alternatively, the water resistant or water impermeable fibre-based packing material may be a water resistant or water impermeable fibre-based sphere or hemi-sphere. Where the product is a water resistant or water impermeable fibre-based sphere or hemi-sphere, the product may be used in place of packaging particles such as packing ‘peanuts’. Other uses include the formation of 3D-shaped products, cups such as coffee cups, container lids, cup lids such as coffee lids, bottle components, trays, any other suitable 3D-shape, or the like. In one particular example, the product may form a shaped packaging insert to protect a boxed electronic product, item of white goods, or similar object which may benefit from packaging material shaped to conform to a particular product. In effect, the shape and dimensions of the product formed from the methods of the present invention may be limited only by the limitations of shapes and configurations imparted by available pressing apparatus, moulds, and the like. The product may therefore include a three-dimensional shape including air-laid pulp and one or more wetting agents. In another example, the product may include a three-dimensional shape including air-laid pulp and one or more sols.

[0036] The air-laid pulp, intermediate pulp, and/or moulded product may be free or substantially free of hydrocarbon-based polymers and plastics. Therefore, the air-laid pulp or intermediate pulp used in the method of the invention, and/or the product formed using the method of the invention may have no, or substantially no, components sourced from oil and gas feedstocks. In many traditional products formed from pulp, hot processes at temperatures of up to 300 °C or more are used to form impermeable barriers from plastics or hydrocarbon-based polymers applied to the intermediate pulp, which melt to form an impermeable barrier. The inventor of the present invention has understood that application of an impermeability-promoting functional additive as part of the wetting agent, such as a sol, to a pulp in the absence of plastic or hydrocarbon-based polymers may enable the formation of a water resistant or water impermeable product. Without being bound by theory, fluid resistance or fluid impermeability promoting wetting agents such as sols described herein are believed to form network structures that obstruct the pore structure of the fibrous material and prevent passage of fluid. Where the components of the fluid resistance or fluid impermeability promoting functional additive are selected to impart one or more additional or alternative functions, the formed network may reside on or close to the surface of the fibrous product such that the network is able to provide functionality at the interface point of the fibrous product. In an example, a sol applied to an air-laid pulp may permeate the pore volume and internal void volume of the air-laid pulp. When the resulting intermediate pulp is hot-pressed according to the methods described herein, the pore structure will at least partially collapse around the sol contained within, promoting contact between the internal pore and/or void walls with the sol. As the sol naturally dries, or is dried by other means, the sol may obstruct the pore volume of the fibrous material and form a coating on the surface of the hot-press moulded product, thus forming a fluid resistant or fluid impermeable barrier. Some wetting agents, such as water, may promote water or fluid resistance in the moulded product without imparting long-term impermeability. The use of such a wetting agent prior to the hot-pressing of the intermediate pulp is believed to incite hydration and other reactions within the structure of the air-laid pulp which may cause a closing and/or narrowing of the pore structure in the resulting moulded product. The closed pore structure therefore resists the permeation of fluid more effectively than a moulded product with a more open pore structure.

[0037] The method may include any number of additional method steps as desired. The method may include one or more additional wetting steps where liquid is applied to the air-laid pulp, intermediate pulp and/or product. Wetting the air-laid pulp, intermediate pulp and/or product may further aid in the processing of the air-laid pulp, intermediate pulp, and/or product through one or more additional processes forming part of the method. Where one or more further wetting steps are present, the wetting agent used in each step may be the same or different depending on the objective of the end user. In an example, a first wetting agent may be applied during a first wetting step to impart the property of water resistance or water impermeability to the moulded product. A second wetting step may then occur to impart a desired optical characteristic to the moulded product. The method may include the application of a functional coating and/or barrier to the intermediate pulp or moulded product. The functional coating may be formed from any material selected to impart one or more desired properties to the intermediate pulp and/or product. The functional coating and/or barrier may be a water-based coating and/or barrier, or may be formed from a water-based functional material. For example, the functional coating may be formed from one or more sols as described herein. The functional coating may be formed from a material selected to promote hydrophobicity, oleophobicity, anti-fouling, anti-biofouling, stain resistance, anti-microbial properties, optical transparency, optical opacity, anti-reflectivity, adhesion promotion, any other suitable property, or any combination thereof. The method may include one or more additional hot-press or cold-press method steps. The additional hot-press or cold-press steps may be carried out on the air-laid pulp, intermediate pulp and/or moulded product as desired. The method may include one or more additional hot- or cold-press steps wherein the pulp, intermediate pulp or product is subjected to pressure. The method may include drying the pulp, intermediate pulp and/or product. Drying the pulp, intermediate pulp and/or product may involve heating and/or applying energy to the pulp, intermediate pulp, and/or moulded product using a heater, oven, heat exchanger, heat gun, infrared source, any other suitable drying means, or any combination thereof. The method may include cutting, slicing, or otherwise freeing discreet shapes from the air-laid pulp, intermediate pulp, and/or moulded product during one or more pressing steps. For example, where an intermediate pulp is present in a mould, the application of pressure via one or more further mould, plate, or equivalent components may also cut, slice, or separate portions of the intermediate pulp from other portions of the intermediate pulp present in the mould. In this manner, smaller products, smaller portions of products, or shapes that would not be achievable without cutting or slicing the intermediate pulp may be obtained using the methods described herein. For the avoidance of doubt, the product, intermediate product, or feedstock air-laid pulp material may be cut, sliced, and/or separated at any suitable point in the method. In one example, the product may be cut, sliced, and/or separated after the pulp has been pressed and dried. In another example, the product may be cut, sliced, and/or separated when the product is an intermediate product between any two other method steps.

[0038] Figure 2 shows a flow diagram of various permutations of methods 200 within the scope of the invention. The method 200 of Figure 2 includes the method steps of applying 201 a wetting agent to air-laid pulp to form an intermediate pulp and hot-pressing 202 the intermediate pulp to form a moulded product. The method of Figure 2 includes various optional additional method steps which may be performed prior to application of the wetting agent to the air-laid pulp. These steps include applying 203A a functional coating and/or barrier to the air-laid pulp, drying 203B the air-laid pulp, hot-pressing 203C the air-laid pulp, or cold-pressing 203D the air-laid pulp. Various further optional additional method steps are shown which may be performed prior to the cold-pressing of the intermediate pulp to form a moulded product. These steps include applying a wetting agent to the intermediate pulp, applying 204A a functional coating and/or barrier to the intermediate pulp, drying 204B the intermediate pulp, hot-pressing 204C the intermediate pulp, or cold-pressing 204D the intermediate pulp. Yet further optional additional method steps are shown which may be applied to the product following its formation by cold-press. These steps include applying 205A a wetting agent to the moulded product, applying 205B a functional coating and/or barrier to the moulded product, drying 205C the moulded product, hot-pressing 205D the moulded product, or cold-pressing 205E the moulded product. Although Figure 2 shows a flowchart with just one of steps 203A to D, 204A to D and 205A to E being carried out as the method proceeds, the skilled person with the benefit of this disclosure will appreciate that any number of such steps could be carried out in any combination at any point in the method depending upon the objectives of the method.

[0039] Figures 3A to 3E show examples of fibre-based bubble wrap that may be formed using the methods described herein. Figure 3A shows a cross-section of a sheet of fibre-based bubble wrap 310 showing bridging portions 311 and hemi-spherical protrusions 312. The protrusions 312 each protrude in the same direction relative to the bridging portions 311 such that the protrusions 312 are all on the same side of the fibre-based bubble wrap 310 when the bridging portions 311 are positioned such that they are substantially linear and/or substantially planar in alignment. The hemi-spherical protrusions each define a cavity 313 within the sheet of fibre-based bubble wrap 310. The fibre-based bubble wrap 310 may be stacked with other sheets of fibre-based bubble wrap 310 by placing the protrusions 312 of one sheet into the cavities 313 of another sheet with which the fibre-based bubble wrap is to be stacked. Figure 3B shows a cross-section of a sheet of fibre-based bubble wrap 320 showing bridging portions 321 and hemi-spherical protrusions 322 and 323. The protrusions 322 protrude upwards relative to the bridging portions 321 whereas protrusions 323 protrude downwards relative to the bridging portions 321 such that the upward protrusions 322 and downward protrusions 323 are each on different sides of the fibre-based bubble wrap 320 when the bridging portions 321 are positioned such that they are substantially linear and/or substantially planar in alignment. The hemi-spherical protrusions 322 and 323 each define a cavity 324 within the sheet of fibre-based bubble wrap 320. The fibre-based bubble wrap 320 may be stacked with other sheets of fibre-based bubble wrap 320 by placing the protrusions 322 and 323 of one sheet into the cavities 3324 of other sheets with which the fibre-based bubble wrap is to be stacked.

[0040] Figure 3C shows a cross-section of a sheet of fibre-based bubble wrap 330 showing bridging portions 331 and hemi-spherical protrusions 332. In a manner similar to the bubble wrap shown in Figure 3A, the fibre-based bubble-wrap 330 of Figure 3C has protrusions 332 protrude upwards on the same side of bridging portions 331. The cavities 333 of the bubble wrap 330 are enclosed such that the cavities 333 contain an enclosed pocket of gas which may be air. While the fibre-based bubble wrap 330 is described with reference to enclosed cavities 333, the cavities may instead be at least partially filled with pulp and so may be formed from, and/or at least partially filled with, the same pulp material used to form the sheet of fibre-based bubble wrap 330. In this manner, the hemi-spherical protrusions 332 may be filled such that they are partially or substantially solid. Figure 3D shows a cross-section of a sheet of fibre-based bubble wrap 340 showing bridging portions 341 and hemi-spherical protrusions 342 and 343. In a manner similar to the bubble wrap shown in Figure 3B, the fibre-based bubble-wrap 340 of Figure 3D has upward protrusions 343 and downward protrusions 344 that protrude from different sides of bridging portions 341 when the bridging portions 341 are arranged such that they are arranged in a substantially linear and/or substantially planar manner. The cavities 344 of the bubble wrap 340 are enclosed such that the cavities 344 contain an enclosed pocket of gas which may be air. While the fibre-based bubble wrap 340 is described with reference to enclosed cavities 344 the cavities may instead be at least partially filled with pulp and so may be formed from, and/or at least partially filled with, the same pulp material used to form the sheet of fibre-based bubble wrap 340. In this manner, the hemi-spherical protrusions 342 and/or 343 may be filled such that they are partially or substantially solid.

[0041] Figure 3E shows another example of fibre-based bubble wrap 350 which may be formed using the methods disclosed herein. The fibre-based bubble wrap 350 includes bridging portions 351 and substantially spherical portions each formed from an upward protrusion 352 and a downward protrusion 353. Each substantially spherical portion includes an internal volume 354 which may be a hollow cavity or may be at least partially filled with solid. The solid in the internal volume 354, where present, may be the pulp material used to form the remainder of the sheet of fibre-based bubble wrap 350. The sheet of fibre-based bubble wrap 350 may be formed as one piece. For example, a positive and negative mould may be used to form the upwards and downward protrusions 352 and 353 from a single mass of pulp used in the manufacture of the fibre-based bubble wrap 350. Alternatively, fibre-based bubble wrap 350 may be formed by bringing together and adhering and/or sealing two sheets of the fibre-based bubble wrap 310 shown in Figure 3A. The fibre-based bubble wrap of Figure 3E may be subjected to one or more further processes following its formation. In one example, a cutting process may be used to free the substantially spherical portions formed from an upward protrusion 352 and a downward protrusion 353 from the bridging portions 351. The spherical portions thus freed from the sheet may then be used as packaging peanuts.

[0042] The fibre-based bubble wraps 310, 320, 330, 340, and 350 are only examples and other configurations of fibre-based bubble wrap are contemplated. The fibre-based bubble wrap may not have one or more or any bridging sections. For example, the protruding portions may be adjacent, substantially adjacent, tessellated, or the like. The fibre-based bubble wraps may be flexible or resiliently deformable with properties depending upon the density of the air-laid pulp, the properties of the wetting agent and/or any functional additives used in their formation. For example, using an air-laid pulp of greater grams per square metre (gsm) may increase the strength of the moulded product. Where a fibre-based bubble wrap has a plurality of protrusions, each of the protrusions may be on the same side of the fibre-based bubble wrap when the fibrebased bubble wrap is arranged to be substantially planer. Alternatively, one or more of the plurality of protrusions may be on a different side of the fibre-based bubble wrap from one or more other of the plurality of protrusions when the fibre-based bubble wrap is arranged to be substantially planar. While Figures 3A to 3E show fibre-based bubble wrap with protrusions that are hemispherical in nature, the protrusions may be any suitable three-dimensional shape such as cube-shaped, pyramid-shaped, irregular in shape, or any other suitable shape. Each protrusion of the fibre-based bubble wrap may be substantially identical. Alternatively, one or more or each protrusion of the fibre-based bubble wrap may be different from another protrusion of the fibrebased bubble wrap. The cross-sections in Figures 3A to 3E show rows of protrusions in a pattern which may be repeated in both the x and y axis of a sheet of bubble wrap substantially oriented in the x-y plane. Where protrusions are arranged protruding up and/or down from the x-y plane, the protrusions may be aligned in linear rows, alternating offset rows, or in any other suitable pattern. Alternatively, one or more protrusions may be arranged such that they are not arranged in a regular pattern. For example, the distribution of the protrusions may be irregular or substantially random. Where the fibre-based bubble wrap has a plurality of protrusions, each protrusion may be identical in size. For example, one or more dimensions of each protrusion of the plurality of protrusions may be substantially identical. Alternatively, one or more or each dimension of one or more or each protrusion of the plurality of protrusions may be different. The fibre-based bubble wrap may be formed using reel-to-reel processes which may use one or more roller moulds. In this manner, the fibre-based bubble wrap may be formed using a continuous or intermittently continuous process. Alternatively, the fibre-based bubble wrap may be formed using press apparatus or the like in batch processes. Other processes including a reel-to-sheet process, a sheet-to-reel process, or a sheet-to-sheet process may be used. The processes used to form the fibre-based bubble wrap may be used to form packaging peanuts by including one or more bladed sections in the mould such that protruding sections of the fibre-based bubble wrap are separated from the sheet of fibre-based bubble wrap. Where the fibre-based bubble wrap includes only hemispherical protrusions as shown in Figures 3A to 3D, the hemi-spherical portions may be brought together to form substantially spherical packaging peanuts. The skilled person, with the benefit of this disclosure, will understand that other shapes of protrusions may be adhered in a similar manner to form non-spherical shapes in a substantially identical manner. Where two or more fibre-based moulded products are adhered, they may be adhered using the wetting agent. If the adhesion is enacted prior to the drying of the moulded product then any wetting agent residual in the moulded product may be used, and may be sufficient, to enact the adhesion. In another example, a functional cellulose additive such as nano-cellulose may be used to adhere two or more fibre-based moulded products. The fibre-based bubble wrap may be used in applications such as packaging, cushioning, or the like. The fibre-based bubble wrap may also be used as at least part of another product, composite material, or the like. For example, the fibrebased bubble wrap may be used as part of an insulating air gap. Examples of applications that may use the fibre-based bubble wrap as part of an insulating air gap include construction materials, furniture, or the like. The fibre-based bubble wrap may impart strength or resilience to insulation that would otherwise involve an air or gas gap. The fibre-based bubble wrap may be positioned in and/or throughout an air or gas insulation cavity to strengthen the material or product including such an air or gas insulation cavity. The fibre-based bubble wrap may be used as part of a composite material. Where the composite material includes an insulating layer, the fibrebased bubble wrap may be used as part of such an insulating layer to impart strength and/or fluid resistance or impermeability to the layer of the composite material. Where the fibre-based bubble wrap is used in a composite material, the fibre-based bubble wrap may impart one of more properties of the fibre-based bubble wrap to the composite material. Properties which may be imparted to the composite material by the fibre-based bubble wrap include strength, fluid resistance or fluid impermeability, thermal insulation, or any other property of the fibre-based bubble wrap.

[0043] The method of the present invention is therefore suited to the objectives of forming a fluid resistant or fluid impermeable fibre-based moulded product without the use of hydrocarbon-based polymers of plastics, reducing water consumption in the formation of fluid resistant or fluid impermeable fibre-based products and increasing the speed at which fibre-based products may be manufactured in some circumstances. In particular, the methods disclosed herein allow for the formation of fibre-based products without the use of the quantities of water, disinfectant, and/or anti-bacterial agents that are associated with traditional wet pulp processes. The moulded products formed using the methods of the present invention may be used in a range of industries such as the automotive, engineering, construction, aviation, marine, defence, electronics (including photo-electronics and sensors), energy (including batteries, energy storage and renewable energy), photonics, food, medical, household products, paper, adhesives, interior or exterior decoration, home improvement, additive manufacturing, oil and gas, separation and purification, fashion, general packaging, and cosmetics industries. In an example, the method of the present invention may be used in the formation of primary, secondary or tertiary packaging material for any suitable industry or purpose.

EXAMPLES

[0044] The invention may be further understood in consideration of the following examples. All chemicals were used as received without further purification.

Example 1

[0045] Water was rolled onto the surface of an air-laid pulp which was subsequently moulded using reel-to-reel cold press moulding to form a fibrous-bubble wrap.

[0046] Examples 2 to 20 provide various methods by which wetting agent sols that may be applied to a pulp may themselves be formed.

Example 2 Formation of a sol:

[0047] Tetraethyloxysilane (100%, 5.5 ml) was added dropwise to a mixture of ethanol (7 ml) and aqueous HCI (0.1 M, 1.7 ml). The solution was stirred for approximately 40 hours until formation of a sol.

Example 3 Formation of a sol:

[0048] Titanium (IV) Ethoxide (100%, 5.5 ml) was added dropwise to a mixture of ethanol (7 ml) and aqueous HCI (0.1 M, 1.7 ml). The solution was stirred for approximately 2 hours until formation of a sol.

Example 4 Formation of a sol:

[0049] Methyltriethyloxysilane (100%, 7.5 ml) was added dropwise to a mixture of ethanol (15 ml) and aqueous HCI (0.1 M, 2 ml). The solution was stirred for approximately 1 hour until formation of a sol. Example 5 Formation of a sol:

[0050] Titanium isopropoxide (9 g) was added to a mixture of ethanol (6.5 ml) and aqueous HCI (0.1 M, 1 .8 ml). The mixture was stirred for approximately 30 minutes until formation of a sol.

Example 6 Formation of a sol:

[0051] Zirconium isopropoxide (8.5 g) was added to a mixture of ethanol (6.3 ml) and aqueous HCI (0.1 M, 1.6 ml). The mixture was stirred for approximately 1 hour until formation of a sol.

Example 7 Formation of a sol:

[0052] Methyltriethyloxysilane (100%, 5.8 ml) was added dropwise to a mixture of ethanol (6.2 ml) and aqueous NaOH (0.1 M, 1.5 ml). The solution was stirred for approximately 30 minutes until formation of a sol.

Example 8 Formation of a sol:

[0053] Aluminium isopropoxide (9.2 g) was added to a mixture of ethanol (6.5 ml) and aqueous HCI (0.1 M, 1.6 ml). The mixture was stirred for approximately 1 hour until formation of a sol.

Example 9 Formation of a sol:

[0054] A silicon alkoxide precursor mixture (5 ml) composed of 50% tetraethyloxysilane and 50% methyltriethyloxysilane was added dropwise to a mixture of ethanol (10 ml) and aqueous NaOH (0.1 M, 2 ml). The solution was stirred for approximately 30 minutes until formation of a sol.

Example 10 Formation of a sol:

[0055] Solution A- Titanium (IV) Ethoxide (5 ml) was added dropwise to ethanol (10 ml). Solution B- 5 ml of solution A added to a silicon alkoxide precursor mixture (5.2 ml) composed of 50% tetraethyloxysilane and 50% phenyltriethoxysilane. The mixture was added dropwise to a mixture of ethanol (8.2 ml) and aqueous HCI (0.1 M, 1.8 ml). The solution was stirred at room temperature for approximately 1 hour until formation of a sol.

Example 11 Formation of a sol:

[0056] A silicon alkoxide precursor mixture (5.2 ml) composed of 50% tetraethoxysilane and 50% phenyltriethoxysilane were added dropwise to a mixture of ethanol (10 ml) and aqueous HCI (0.1 M, 2 ml). The solution was stirred at room temperature for approximately 6 hours until formation of a sol. Example 12 Formation of a sol:

[0057] Cationic Starch (CS; 7 mg) was dispersed in a mixture of ethanol (10 ml) and aqueous HCI (0.1 M, 1.6 ml) to produce a solution with pH 2. To this stirred solution, silicon alkoxide precursor (5.2 ml) composed of 100% tetraethyloxysilane was added dropwise before stirring was continued for a further 8 hours.

Example 13 Formation of a sol:

[0058] Cationic Starch (CS; 7 mg) was dispersed in a mixture of ethanol (10 ml) and aqueous HCI (0.1 M, 1.6 ml) to produce a solution with pH 2. To this stirred solution, silicon alkoxide precursor (5.2 ml) composed of 100% methyltriethyloxysilane was added dropwise before stirring was continued for a further 2 hours.

Example 14 Formation of a sol:

[0059] Chitosan (6 mg) was dispersed in a mixture of ethanol (12 ml) and aqueous HCI (0.1 M,

2 ml) to produce a solution with pH 2. To this stirred solution, silicon alkoxide precursor mixtures (6 ml) composed of 50% tetraethoxysilane and 50% phenyltriethoxysilane were added dropwise before stirring was continued for a further 1.5 hours.

Example 15 Formation of a sol:

[0060] Wheat flour (7 mg) was dispersed in a mixture of ethanol (8 ml) and aqueous NaOH (0.1 M, 2 ml) to produce a solution with pH 13. To this stirred solution, silicon alkoxide precursor mixtures (5.2 ml) composed of 50% tetraethyloxysilane and 50% methyltriethyloxysilane were added dropwise before stirring was continued for a further 30 minutes.

Example 16 Formation of a sol:

[0061] Cationic Starch (CS; 5 mg) was dispersed in a mixture of ethanol (10 ml) and aqueous NaOH (0.1 M, 1.5 ml) to produce a solution with pH 13. To this stirred solution, methyltriethyloxysilane (5.2 ml) was added dropwise before stirring was continued for a further 20 minutes.

Example 17 Formation of a sol:

[0062] Wheat flour (5 mg) was dispersed in a mixture of ethanol (6 ml), aqueous NaOH (0.1 M, 1 ml) and methyltriethoxysilane (1 ml) to produce a solution with pH 13. To this stirred solution, silicon alkoxide mixtures (1 ml) composed of 50% tetraethoxysilane and 50% phenyltriethoxysilane were added dropwise before stirring was continued for a further 30 minutes. Example 18 Formation of a sol:

[0063] Cationic Starch (CS; 5 mg) was dispersed in a mixture of ethanol (7.6 ml) and aqueous HCI (0.1 M, 1.6 ml) to produce a solution with pH 2. To this stirred solution, silicon alkoxide precursor mixtures (5.2 ml) composed of 50% tetraethyloxysilane and 50% phenyltriethoxysilane were added dropwise before stirring was continued for a further 1 hour.

Example 19 Formation of a sol:

[0064] Wheat flour (5 mg) was dispersed in a mixture of ethanol (6 ml), aqueous NaOH (0.1 M, 1 ml) and methyltriethoxysilane (1 ml) to produce a solution with pH 13. To this stirred solution, triethyloxysilane (1 ml) was added dropwise before stirring was continued for a further 1 hour.

Example 20 Formation of a sol:

[0065] Wheat flour (5 mg) was dispersed in a mixture of ethanol (6 ml), aqueous NaOH (0.1 M, 1 ml) and methyltriethoxysilane (1 ml) to produce a solution with pH 13. To this stirred solution, silicon alkoxide mixtures (1 ml) composed of 50% tetraethyloxysilane and 50% phenyltriethoxysilane were added dropwise before stirring was continued for a further 1 hour.

[0066] Examples 21 to 28 presented in Table 2 demonstrate various wetting agents comprising sols comprising various solvents, biopolymers and alkoxides.

Table 2 Matrix of further sol examples

[0067] Examples 29 to 35 provide examples of various methods within the scope of the present invention by which products may be formed. Example 29

[0068] The sols formed in examples 2, 3, 10, 13, 15, 16, 17, 18, 19, and 20 were each diluted with water, a mixture of water and ethanol. Or a mixture of water and any other solvent disclosed herein, to provide a 5% solution of each sol then applied to an air-laid pulp using spraying techniques. The pulp was shaped using a press for no more than 3 seconds at pressures of around 1000 kg/m²and 6000 kg/m²and a temperature of 200 °C. The pressed pulp products were tested by placing water droplets on the surface of each of the shaped pulp products and allowing the products to rest for a period of 3 hours. After 3 hours, no water was seen to have permeated the surface of the pressed pulp products and observation was stopped.

Example 30

[0069] The sol formed in example 24 was sprayed on to air-laid pulp and the intermediate pulp thus formed was moulded using a hot-press process in accordance with example 29. A gas barrier coating was then applied to the hot-pressed product prior to treatment of the hot-pressed product using an additional hot-press step. The resulting twice hot-pressed product was tested for water impermeability. Water droplets were placed upon the moulded product and left to rest for of 2 hours. No penetration of water into the surface of the product was observed.

Example 31

[0070] The sol formed in example 26 was sprayed on to air-laid pulp and the intermediate pulp thus formed was moulded using a hot-press process in accordance with example 29. The hot- pressed product was then subjected to further hot-press moulding. The double-hot-pressed product was then tested for water impermeability. Water droplets were placed upon the moulded product and left to rest for of 2 hours. No penetration of water into the surface of the product was observed.

Example 32

[0071] Wetting agents including water, sols, and sols including biopolymers were applied to airlaid pulp at different weight percentages of wetting agent to mass of dry air-laid pulp and each intermediate pulp thus formed was moulded in accordance with example 29. A control sample using no wetting agent of any form (i.e. 0 wt%) and dry pulp was also formed. All of the products formed using wetting agent exhibited water resistance and water impermeability when tested. The surface finish of all of the products was assessed visually and is summarised in Table 3 below. Table 3 Surface characteristics of various weight % of sol wetting agents

Claims

1. A method comprising: applying a wetting agent to air-laid pulp to form an intermediate pulp; and hot-pressing the intermediate pulp to form a moulded product.

2. The method according to claim 1 , wherein the air-laid pulp, intermediate pulp, and/or moulded product are free or substantially free of thermoplastic polymers and/or hydrocarbon-based plastics.

3. The method according to claim 1 or claim 2, the method further comprising applying a functional coating and/or barrier to the intermediate pulp or moulded product.

4. The method according to any preceding claim, the method further comprising additionally hot- and/or cold-pressing the air-laid pulp, intermediate pulp, or moulded product.

5. The method according to any preceding claim, wherein the moulded product is a water resistant or water impermeable moulded product.

6. The method according to any preceding claim, wherein the wetting agent is applied to the air-laid pulp by brushing, spraying, spray drying, rolling, dipping, dropping, injecting, transferring, submersion, immersion, mixing, spreading, blading, padding, or any combination thereof.

7. The method according to claim 6, wherein the wetting agent is applied to the air-laid pulp by spraying.

8. The method according to any preceding claim, wherein hot-pressing the intermediate pulp is carried out at a temperature greater than 100 °C.

9. The method according to claim 8, wherein hot-pressing the intermediate pulp is carried out at a temperature of greater than 150 °C.

10. The method according to any preceding claim, wherein hot-pressing the intermediate pulp comprises: pressing the intermediate pulp into at least one mould, pressing the intermediate pulp between at least one plate and at least one other surface, or any combination thereof.

11 . The method according to any of claims 4 to 10, wherein the method further comprises additionally hot- and/or cold-pressing the air-laid pulp, intermediate pulp, or moulded product, further wherein additionally hot- and/or cold-pressing the intermediate pulp comprises: pressing the intermediate pulp into at least one mould, pressing the intermediate pulp between at least one plate and at least one other surface, or any combination thereof.

12. The method according to claim 10 or 11, wherein the mould comprises one or more fluid escape elements configured to allow fluid, optionally wetting agent in the form of vapour and/or liquid, to exit the mould, optionally wherein the one or more fluid escape elements comprise one or more holes, vents, apertures, flow passages, conduits, pipes, pathways, or any combination thereof.

13. The method according to any preceding claim, the method further comprising applying heat to dry the air-laid pulp, intermediate pulp, or product.

14. The method according to any preceding claim, the method further comprising drying the air-laid pulp, intermediate pulp, or product without the direct application of energy.

15. The method according to any preceding claim, wherein the wetting agent comprises water.

16. The method according to any preceding claim, wherein the wetting agent comprises a sol.

17. The method according to any claim 16, wherein the sol comprises a solvent, an alkoxide, and a catalyst.

18. The method according to claim 17, wherein the sol further comprises a biopolymer.

19. The method according to claim 18, wherein the biopolymer comprises a starch.

20. The method according to claim 19, wherein the starch comprises a cationic starch.

21. The method according to claim 20, wherein the cationic starch is selected from quaternary ammonium type cationic starch, tertiary ammonium type cationic starch, and any combination thereof.

22. The method according to claim 21 wherein the biopolymer comprises a flour.

23. The method according to claim 22, wherein the flour comprises 5 to 85% starch, 0 to 30% hemi-cellulose, 0 to 50% cellulose, 0 to 25% lignin, 0 to 35% protein and 0 to 25% ash.

24. The method according to claim 22 or 23, wherein the flour is selected from the group wheat flour, barley flour, lentil flour, bamboo flour, corn flour, oat flour, rye flour, buckwheat flour, rice flour, chickpea flour, green pea flour, or any combination thereof.

25. The method according to any of claims 17 to 24, wherein the catalyst is at least one of an acid and a base.

26. The method according to claim 25, wherein the catalyst is selected from hydrochloric acid, citric acid, nitric acid, acetic acid, sodium hydroxide, potassium hydroxide, ammonia, and any combination thereof.

27. The method according to any of claims 17 to 26, wherein the alkoxide is selected from silicon alkoxides, metal alkoxides, phosphorus alkoxides, and any combination thereof.

28. The method according to any of claims 17 to 26, wherein the alkoxide is selected from n-propyltriethoxysilane, tetrapropyl orthosilicate, titanium(IV) tert-butoxide, titanium(IV) isopropoxide, triethyloxysilane, methyltriethyloxysilane, triethoxy(octyl)silane, phenyltriethoxysilane, titanium(iv) ethoxide, triethoxysilylcyclopentane, (3-glycidyloxypropyl) trimethoxysilane, cyclopentyltriethoxysilane, 3-amino-propyltriethoxysilane, triethoxy-3-(2imidazolin-1-yl)propylsilane, and any combination thereof.

29. The method according to any of claims 17 to 28, wherein the solvent comprises water, one or more alcohols, and any combination thereof.

30. The method according to claim 29, wherein the solvent comprises methanol, ethanol, isopropanol, butanol, ethylene glycol or any combination thereof.

31. The method according to any preceding claim, wherein the wetting agent comprises one or more functional additives.

32. The method according to claim 31, wherein the one or more functional additives comprise photoinitiators, resins, oils, dyes, salts, anti-microbial agents, mineral or other inorganic particles, surfactants, biopolymers, composite particles and/or metal particles.

33. The method according to claim 31 or 32, wherein the wetting agent delivers the one or more functional additives into the internal structure of the air-laid pulp.

34. The method according to any preceding claim, wherein hot-pressing the intermediate pulp comprises applying a pressure of at least 1000 kg/m² to at least a part of the intermediate pulp.

35. The method according to any of claims 1 to 33, wherein hot-pressing the intermediate pulp comprises applying a pressure of about 6000 kg/m² to at least a portion of the intermediate pulp.

36. The method according to any preceding claim, wherein hot-pressing the intermediate pulp comprises applying pressure to a portion of the intermediate pulp for a time of from less than or equal to 1 second to up to 10 seconds, optionally wherein pressure is applied for less than or equal to 5 seconds.

37. The method according to any preceding claim, wherein the moulded product is a fibrebased moulded bubble wrap.

38. The method according to any preceding claim, wherein the moulded product is a food or beverage packaging product.

39. A fluid resistant or fluid impermeable fibre-based packaging material comprising airlaid pulp comprising a moulded product formed by the method of any preceding claim.

40. The fibre-based packaging material of claim 39 comprising a sol comprising a solvent, an alkoxide, and optionally a biopolymer.

41. The fibre-based packaging material of claim 39 or 40, wherein the fibre-based packaging material is a fibre-based bubble wrap.

42. The fibre-based packaging material of claim 41, wherein the fibre-based bubble wrap is formed using a reel-to-reel process, a reel-to-sheet process, a sheet-to-reel process, or a sheet-to-sheet process.

43. The fibre-based packaging material of claim 39 or 40, wherein the fibre-based packaging material is a fibre-based packaging peanut.