GB2579686A

GB2579686A - Method for producing a moulded article

Info

Publication number: GB2579686A
Application number: GB1905997.1A
Authority: GB
Inventors: E Minkley Rowan; F C Nicoll Robert
Original assignee: Chip S Board Ltd
Current assignee: Chip S Board Ltd
Priority date: 2018-11-01
Filing date: 2019-04-29
Publication date: 2020-07-01
Also published as: WO2020089573A1; GB201817909D0; GB201905997D0

Abstract

A method for producing a moulded article using potato waste, the method comprising fermenting the potato waste 101, and moulding 102 and heating 103 the fermented potato waste to form a moulded article. The method may comprise additional steps of pasteurisation, adjusting the pH level and comminuting or micronizing the potato waste prior to fermentation. The fermentation may be carried out by bacteria that may be present in the potato waste or that may be added to the potato waste, this includes Lactic acid bacteria e.g. Lactobacillus delbruekii, Lactobacillus amylophilus, Lactobacillus bulgaricus and Lactobacillus lechmannii. The fermentation step increases the concentration of lactic acid and this may polymerise into polylactic acid in situ. Starch may be commingled prior to the moulding and heating step. The moulded article may be chip-board, a panel or an interior design product such as furniture. Filler materials e.g. plant based fibres from bamboo, wood, sugarcane, flax, hemp or brewers grain may be added to the potato waste. The moulded article may be used in an interior design product such as a furniture product. An example of preparing a moulded bio-plastic board using the claimed method is also disclosed.

Description

Method for producing a moulded article The present invention relates to moulded articles and methods for producing moulded articles. In particular, the present invention relates to moulded articles formed from organic waste, and in particular, potato waste.

Artificial composite materials made from wood, including particle boards such as MDF (medium density fibreboard) and chipboard or plywood, are widely used in construction and furniture as a substitute for solid wooden panels. Such composite boards are typically much cheaper than solid wood, whilst retaining sufficient mechanical strength and durability for many applications.

However, such particle boards usually use hazardous chemical components in their manufacture, which leads to safety risks both during manufacture and afterwards. For example, particle boards are typically made using artificial resins such as formaldehyde resins or amino resins. Such resins are generally non-renewable and toxic or carcinogenic chemicals arising from the resins can be released to the atmosphere from the surface of the board and in particular in dust generated during cutting or drilling particle boards. Accordingly, there is a need for materials that can be substituted for conventional particle boards that can reduce or eliminate the safety hazards, and can be derived from renewable sources.

It has been surprisingly found that moulded articles such as boards or panels, having favourable mechanical properties, can be produced from fermented organic waste.

Thus, according to a first aspect, there is provided a method for producing a moulded article using organic waste, the method comprising: (i) fermenting the organic waste; (ii) moulding and heating the fermented organic waste from step (i) to form a moulded article.

Organic waste as discussed herein will be understood to refer to material derived from biological sources, for example, plant-based material. Preferably the plant based-material is derived from a high-starch cellulosic plant material, for example cellulosic plant material containing at least 10 wt.% starch, or at least 15 wt.% starch. Preferably, the plant based-material is potato waste.

Without wishing to be bound by any particular theory, it is believed that by fermenting organic waste, and potato waste in particular, prior to moulding and heating, the concentration of certain chemical components in the organic waste may be increased, which may in turn lead to the formation of an improved moulded article such as a board or a panel.

In particular, it is believed that fermentation of the organic waste may increase the concentration of lactic acid, which may contribute to improved mechanical properties in a moulded article.

According to a further aspect, there is provided a method for producing a moulded article using potato waste, the method comprising: (i) fermenting the potato waste; (ii) moulding and heating the fermented potato waste from step (i) to form a moulded article.

Potato waste as referred to herein will be understood to refer to potato derived product streams. It will be appreciated that such "waste" streams may be by-products from processing potatoes for consumption, for example potato peels and/or potato flesh such as discarded offcut material from the potatoes or malformed potatoes. Nonetheless, it will be understood that the potato waste referred to herein may also include potato derived material that is not recovered as a by-product of a different process, but from raw potatoes as a feedstock intended for the present method.

It will be understood that the potato waste referred to herein will comprise potato peels or potato flesh, or combinations thereof. Where a combination of potato peels and potato flesh is used, it will be understood that these components may be processed separately prior to step (ii), or may be processed as a single mixture. While potato peels and potato flesh are considered to refer to different waste streams, it will be appreciated that potato peels will typically comprise an amount of potato flesh attached to the peel. Potato peel can be obtained from potatoes by any suitable method, for example peels may be removed by steaming under pressure followed by washing and centrifugation. Potato flesh will typically be in the form of smaller raw "chips" cut from whole potatoes but may also be in the form of a homogenised puree. In preferred embodiments, the potato waste comprises 40 wt.% or more potato flesh and/or skins, preferably 50 wt.% or more potato flesh and/or skins, for example 60 wt.% or more potato flesh and/or skins, or even 80 wt.% or more potato flesh and/or skins.

The potato waste may also include other waste streams such as materials derived from water run-off generated during processing of potatoes. For example, this may include "white starch", consisting of relatively pure potato starch that is collected from water run-off during potato processing, or potato starch purposefully extracted from raw potatoes.

According to the present method, the potato waste is fermented in step (i). As will be appreciated, fermentation refers to the processing of the potato waste by bacteria, resulting in chemical changes to the potato material. It will be appreciated that the bacteria present naturally in the potato waste may perform the fermentation. In some instances, additional bacteria may optionally be added to the potato waste before fermentation to enhance or alter the fermentation process. In particular, without wishing to be bound by any particular theory, it is believed that lactic acid bacteria present in the potato waste convert carbohydrates in the potato into lactic acid during the fermentation step. It is believed that the lactic acid may form polylactic acid in situ during the process, which may lead to improved mechanical properties of the moulded article. In addition, the fermentation step is believed to produce a mixture of volatile fatty acids that may form complex polymeric structures during step 00. In addition to lactic acid, volatile fatty acids that may be produced by the fermentation step include formic acid, acetic acid, propionic acid, butyric acid and hexanoic acid. For example, acetic acid formed during the fermentation may contribute to acetylation of starch or cellulose in the potato waste. The fermentation bacteria may also produce biopolymers such as polyhydroxyalkanoates that may contribute to the favourable properties of the moulded article.

The fermentation step may be carried out in any suitable way known to the person skilled in the art. It will be appreciated that the fermentation is typically conducted under anaerobic conditions, for example by keeping the potato waste in a sealed container for a period of time. The fermentation may be carried out for any suitable length of time. Preferably the fermentation is conducted for at least 48 hours, and/or may be conducted for up to 14 days. In some instances, the fermentation is conducted for at least 5 days or at least 8 days, for example at least 12 days. The fermentation may be carried out at any suitable temperature, for example at ambient temperature (typically 15 °C to 30 °C). In some instances the fermentation is carried out at a temperature of 20 °C or more, for example 25 °C or more. Preferably, the fermentation is conducted at a temperature of from around 21 to 42 °C, in particular from 35 to 40 °C. The fermentation may comprise allowing the potato waste to remain static during the fermentation step, or alternatively in some instances the potato waste may be mechanically disturbed during fermentation, for example by rotary fermentation.

The pH level of the mixture during fermentation may be from about 3.5 to 7, and preferably from about 4 to 6.5. It will be appreciated that volatile fatty acids produced during fermentation may lower the pH level of the mixture. Thus, the process may comprise adjusting the pH level of the mixture being fermented during the fermentation step (i) to maintain an optimal pH level or range, for example by periodic addition of a basic substance such as sodium hydroxide. By way of example, sodium hydroxide may be added at a concentration of around 1g/L.

The process may comprise pasteurising the potato waste to be used in fermentation step (i) and adding bacterial cultures to the pasteurised potato waste prior to the fermentation step (i). However, pasteurisation is not essential. The pasteurisation may comprise heating the potato waste to a temperature of from around 100 °C to 130 °C, for example 115 °C to 125 °C, such as about 121 °C. The pasteurisation may be conducted for from 10 minutes to 1 hour, for example from 20 minutes to 40 minutes, such as about 30 minutes. The potato waste may additionally be stirred during the pasteurisation.

Bacteria that may be present in the potato waste, and/or that may be added to the potato waste before the fermentation step described previously, optionally after pasteurisation, include Lactic acid bacteria, for example species of the Lactobacillus genus, such as Lactobacillus delbruekii, Lactobacillus amylophilus, Lactobacillus bulgaricus and Lactobacillus leichmannii.

In some instances, the potato waste may be fermented under higher temperature conditions by adding thermophilic bacteria to the potato waste prior to step (i), without a pasteurisation step. For example, bacteria such as Geobacillus stearothermophilus may be added to the potato waste and the fermentation step conducted at a temperature of at least 50 °C, for example from around 50 °C to 70 °C such as from around 55 °C to 65 °C. Such a high temperature fermentation may be a two-step fermentation and the high temperature step may be carried out followed by fermentation at the temperatures described previously. For example, fermentation may be conducted for from 1 to 24 hours at a high temperature, followed by fermentation for at least 24 hours at lower temperatures as described previously.

The fermentation step may be monitored to determine the concentration of volatile fatty acids such as lactic acid and acetic acid, and the fermentation may be controlled, for example by adjusting the length of time of the fermentation or by addition of further feedstocks or bacterial cultures, until a threshold concentration of volatile fatty acids is reached. For example, the fermentation may be controlled to achieve a concentration of lactic acid in the range of from 7 to 31 g/L, and/or may be controlled to achieve a concentration of acetic acid in the range of from 6 to 35.5 g/L. Control may also include using a previously tested set of conditions known to achieve a particular concentration of volatile fatty acids such as lactic acid and/or acetic acid.

"Moulding" as referred to herein will be understood to mean physically forming the potato waste into a desired shape and it will be appreciated that this may be done in any suitable way. The moulding may be performed by hand, or mechanically. For example the moulding may comprise mechanically pressing the fermented potato waste, for example by using a powered or manually operated mechanical press.

In some preferred embodiments, the potato waste is micronized to reduce the particle size prior to the moulding step. Micronizing the potato waste may be performed by any suitable method, for example by mechanically grinding the potato waste such as by milling, e.g. hammer milling. In some instances, the potato waste may be passed through a sieve to control particle size. Suitably, the micronized potato waste may be passed through a 0.25 mm mesh.

In some preferred embodiments, the fermented potato waste used in step (ii) has a water content of from 10 wt.% to 50 wt.%, for example from 20 wt % to 45 wt.%. In some preferred embodiments, the fermented potato waste used in step (ii) has a water content of from 40 wt.% to 85 wt.%, for example from 50 wt.% to 80 wt.% or from 55 wt.% to 75 wt.%. The fermented potato waste used in step OD may have a water content of less than 70 wt.%. It has been found that limiting the water content of the fermented potato waste used in step (ii) may reduce curing times, decrease the rate of warping or cracking, and may lower the failure rate during compression.

It will be appreciated that the raw potato waste will typically contain water which can contribute to the water content of the fermented potato waste. The potato waste used in step (i) may comprise at least 50 wt.% water, and/or may comprise up to 95 wt.% water, for example from 65 wt.% to 85 wt.%. For example, potato peels referred to herein may contain from around 70 to 92 wt. % water, potato flesh chips referred to herein may contain from around 75 to 89 wt.% water, white potato starch referred to herein may contain from around 25 to 38 wt.% water, and potato puree may contain from around 65 to 78 wt.% water. Water may also be added to the potato waste or fermented potato waste prior to step (ii).

In some preferred embodiments, at least a portion of the fermented potato waste is dried following the fermentation step (i). The drying may be conducted by any suitable method. In some preferred embodiments the fermented potato waste is dried by physically or mechanically dewatering the fermented potato waste, for example by pressing it against a water permeable filter. The partially dried fermented potato waste may then be further dried by thermally desiccating at elevated temperatures up to 80 °C. In some preferred embodiments, the dried potato waste is then micronised and optionally sieved.

By drying the fermented potato waste after step (i), the ratio of the solid potato waste to water and other additional components may be more easily controlled, which may help the repeated production of moulded articles having consistent properties. Where the fermented potato waste is dried, it will be appreciated that water will typically be added to the dried fermented potato waste prior to step (ii).

The water content of the fermented potato waste used in step (ii) may be adjusted to achieve the preferred water content discussed previously. The water content may also be optimised differently based on the processing used in step (ii). For example, where compression is used in step (ii), for example to produce a bio-plastic material, the water content of the fermented potato waste may be adjusted, for example by dewatering, to give a water content of around 60 to 80 wt.%, for example 70 wt.% or less such as from 60 to 70 wt.% or 64 to 68 wt.%. Alternatively, where compression is not used in step (ii), the water content of the fermented potato waste may be adjusted, for example by dewatering, to give a water content of around 50 to 80 wt.%, for example 60 wt.% or less such as from 50 to 60 wt.% or from 53 to 57 wt%.

Where the fermented potato waste is dewatered, the water run-off may be collected and distilled to collect volatile fatty acids present with the water, which may be reintroduced into the fermented potato waste used in step (h). Distillation may be performed by any suitable method, for example by vacuum distillation at around 80 to 120 °C. Collected volatile fatty acids may be recombined with the fermented potato waste at any suitable stage of the process, for example before or after drying or dewatering potato waste, and before or after further processing such as mechanical homogenisation. It will be appreciated that volatile fatty acids obtained from water run-off may be combined with the same fermented potato waste stream from which they were derived, or may be added to a separate potato waste stream that may or may not have been dewatered. Volatile fatty acids collected from water run-off may additionally be chemically processed, for example by acetylation of starch or cellulose, prior to being reintroduced into the fermented potato waste.

In preferred embodiments, the method comprises mixing starch with the potato waste prior to moulding and heating in step (ii). It will be appreciated that the potato waste will contain an amount of starch inherently, and mixing starch with the potato waste is intended to refer to adding additional starch to the potato waste. The starch added to the potato waste may suitably be any source of starch and is preferably potato starch, for example white potato starch that is collected from water run-off during potato processing. The starch is preferably fermented as described in relation to other potato waste, although it will be appreciated that where the starch has a low water content, relatively low levels of fermentation may occur.

The starch may be added at any stage of the process, for example before, during or after fermentation step (i), and is preferably mixed with the pre-fermented potato waste and homogenised before using the mixture in step (ii). Preferably, the starch is added in an amount of from 5 wt.% to 40 wt.% as a proportion of the material used in step (ii). In some preferred embodiments, the starch is gelatinised in water prior to mixing with the potato waste. For example, the starch may be gelatinized by mixing with water in an amount of approximately 20% weight/volume and stirring at around 60 °C for 15 minutes. Starch may chemically gelatinized by alkaline treatment, for example treatment with sodium hydroxide (e.g. up to 5 wt.% sodium hydroxide). By gelatinizing the starch in water prior to mixing with fermented potato waste, water and starch may simultaneously be added to dried fermented potato waste, whilst controlling the ratio of each component in the mixture.

The potato waste used in step (i), including any optionally added additional starch, may comprise at least 20 wt.% starch by dry weight of the potato waste, for example at least 30 wt.% starch, at least 50 wt.% starch or at least 70 wt.% starch. Starch content may be measured by any suitable method, for example by standard methods ISO 15914:2004 or ISO 6493:2000.

In some instances, the fermented potato waste used in step (ii) consists essentially of potato derived materials. Nonetheless, it will be appreciated that the fermented potato waste may suitably be mixed with other materials prior to or during step (ii), for example to modify the properties of the final moulded article. Any suitable materials may be mixed with the fermented potato waste, and it will be appreciated that such materials may suitably be added at various stages such as during or before fermentation, between steps (i) and (H) or after/during moulding step 00. Added materials may act as fillers to add bulk to the moulded article or to enhance the mechanical strength or toughness of the moulded article. Additional materials may be synthetic or non-synthetic materials, for example plastics. Preferably, the fermented potato waste used in step (ii) may include non-synthetic, renewable materials such as plant-based materials. Additives may include proteinaceous components from agricultural waste streams such as gluten from wheatbran. In particular, the fermented potato waste used in step (ii) may include fibres derived from bamboo, wood, sugarcane, flax, hemp or brewers grain, for example. Processed or extracted materials such as microcrystalline cellulose, nanocellulose, cellulose acetate, refined lignocellulosic fibres, lactic acid or citric acid, polyhydroxyalkanoates and volatile fatty acids that may be derived from industrial agricultural waste may also be added.

Fibres added to the potato waste may for example be lignocellulosic material from raw, sources or fermented feedstocks. Fibres added to the fermented potato waste may have a particle size of around 1 to 4 mm, and may be selected for example by passing fibres through a sieve having a 1 to 4mm mesh. The fibres may be processed to reduce particle size prior to mixing with the fermented potato waste, in particular fibres may be milled, for example hammer milled, and may be dried before milling. The fibres may be added in an amount of around 10 to 25% by weight of the fermented potato waste used in step (ii).

Prior to the fermentation step (i), feedstocks may be pre-treated with enzymes such as cellulase, hemicellulase and amylase to increase the concentration of fermentable reducing sugars in the feedstocks before fermentation to improve the yield of volatile fatty acids. The amounts of such enzymes that are added may vary based on the composition of the feedstock to step (i), by way of example, enzymes may be added in a concentration of from around 10 to 40 U per gram of dry feedstock. Nonetheless, the pre-treatment of feedstocks with enzymes is not essential and in some preferred embodiments, the potato waste used in the fermentation step (i) does not undergo a pre-treatment by adding enzymes to the feedstock.

Other materials may be added to alter the visual appearance of the moulded article, such as dyes or pigments. Such pigments or dyes may suitable be natural or synthetic pigments or dyes.

Additives may be added to the potato waste to adjust mechanical properties of the moulded article. In particular, plasticisers may be added to the fermented potato waste to decrease the glass transition temperature of polymer matrix components in the moulded article. Plasticisers may generally be added in an amount of up to around 50 wt.% by weight of the fermented potato waste used in step 00, preferably up to around 35 wt.%, and it will be appreciated that the amount of plasticiser added may depend on the particular plasticiser used and the desired result. Examples of plasticisers that may be added include polyols such as D-sorbitol, D-glucose, ethylene glycol, polyethylene glycol, carboxylic acids and esters of polycarboxylic acids such as maleic acid, amino acids such as proline, phthalates such as diethyl phthalate or dimethyl phthalate. Particular examples of plasticisers include one or more of diethyl phthalate (e.g. 10 to 25 wt.%), dimethyl phthalate (e.g. 10 to 22.5 wt.%), ethylene glycol (e.g. 1 to 7 wt.%), triacetin (e.g. 5 to 25 wt.%), tributyl citrate (e.g. 20 to 32.5 wt.%), or triethyl citrate (e.g. 10 to 20 wt.%).

The fermented potato waste mixture used in step (ii), optionally containing additional starch and/or non-potato derived materials may suitably be homogenized prior to step (ii). Homogenising the mixture may help produce a moulded article having improved consistency of mechanical properties and appearance. Alternatively or in addition to said homogenisation, the potato waste or other materials used in fermentation step (i) may be mechanically homogenised prior to the fermentation step increase surface area and porosity.

Homogenisation may be performed in any suitable way, for example by mechanical blending, melt blending or extrusion processes such as with a twin screw extruder (in particular where multiple inputs are blended).

The fermented potato waste may be processed to alter the properties of components of the mixture. For example a steam digest of the fermented potato waste (e.g. via pressure cooking of a 20 weight/volume solution) may be used to hydrolyse a fraction of lignocellulosic material prior to step (ii).

In some instances, the fermented potato waste may be processed to extract components of the potato waste for use in step (U) of the method. For example, naturally occurring polymers and fibres including polyhydroxylalkanoates, starch, lignin, pectins and cellulose as well as other fermentation products such as lactic acid may be extracted from the potato waste and optionally separated, with a combination of the extracted components being used as the fermented potato waste in step (ii). Alternatively, extracted components may be added to other mixtures of fermented potato waste to alter the properties of the moulded article.

In step (ii) of the method, the fermented potato waste is moulded and heated. The heating may be performed using any suitable means such as are known by the person of skill in the art. For example, the heating may be performed by heating the moulded potato waste between heated plates, in an oven or by any other suitable method. The heating is preferably to a temperature of at least 100 °C. The heating step may suitably be performed at a temperature of less than 400 °C, for example less than 350 °C or less than 300 °C. For example, the heating in step (ii) may be at a temperature of from 100 °C to 400 °C, and in some instances from 150 °C to 350 °C, for example from 200 °C to 300 °C. In some embodiments, the heating step may be conducted at a relatively low temperature, for example less than 200 °C or less than 150 °C.

The heating step may be conducted for any suitable length of time, and in preferred embodiments, the heating step may be conducted for at least 5 minutes, preferably at least 15 minutes, for example from 15 minutes to 2 hours.

Following the heating step, the moulded article may suitably be allowed to cool to ambient temperature. Preferably, the moulded article is maintained in its shape as it is allowed to cool and cure. For example, the moulded article may be allowed to cool/cure in a forming mesh such as a stainless steel forming mesh. Preferably, the moulded article is allowed to cure for at least 24 hours before further use or, where used, removal from a restraint such as a forming mesh.

The moulding and heating in step (ii) may suitably be performed as a separate moulding step followed by a heating step. Or the moulding and heating steps may be combined into a single moulding and heating step, for example in a heated press.

Moulding may include a continuous process for shaping, and optionally simultaneously heating the fermented potato waste. For example, moulding may include extrusion or continuous shaping by rolling the fermented potato waste. The potato waste may for example be moulded by passage through one or more rollers that compress the potato waste into a sheet, and the rolling may be controlled to adjust the thickness of the sheet produced. In particular, the thickness may be controlled to form thin (thickness of around 1mm to 1cm) flexible articles.

In a preferred embodiment, step (ii) comprises moulding the fermented potato waste and subsequently heating to form the moulded article. It will be appreciated that where the moulding step is performed separately, the moulded potato waste may nonetheless be held in shape, for example between heated plates, during the heating step.

In some preferred embodiments, no compression of the moulded fermented potato waste is conducted during the heating step. For example, the heating of the fermented potato waste may be conducted at about atmospheric pressure. In this way, a moulded fibreboard material may be produced having favourable mechanical properties, for example for use in construction or interior design.

In some embodiments where no compression is used during the heating step, it is preferred to mix dried fermented potato waste with gelatinized starch prior to step (ii) as described previously herein. For example, in preferred embodiments the dried fermented potato waste is mixed in an approximately 1:1 ratio with a gelatinized starch/water mixture, although it will be appreciated that other suitable ratios may be used. It has been found that by using gelatinized starch an improved moulded article may be produced.

In other preferred embodiments, step (ii) comprises simultaneously compressing and heating the fermented potato waste. By compressing the fermented potato waste at the same time as heating, it has been surprisingly found that a translucent bio-plastic material may be produced that has an attractive surface finish and good durability. It will be appreciated that the fermented potato waste may be moulded into shape prior to the heating and compression step.

The pressure during the heating and compression step may be any suitable pressure.

Preferably the pressure is at least 1 bar, for example at least 5 bar, at least 20 bar or at least bar. Suitably the pressure may be from 1 to 40 bar.

During mechanical compression, the pressure may be cycled from 0 bar to the peak pressure, for example up to 40 bar (e.g. 36 bar). The pressure may be cycled several times during the moulding step, for example up to 3 times per hour. The pressure may be applied over a gradient from 0 to peak pressure over a period of time from around 5 to 30 minutes.

The heating and compression step may be performed in any suitable apparatus, for example in a heated press or mould.

The heating and compression step may be carried out for an amount of time as described previously in relation to the heating step. Preferably, the heating and compression step is carried out for at least 30 minutes.

The moulding and heating step may include melt-blending of the fermented potato waste, for example by extrusion. In embodiments, the fermented potato waste may be extruded, for example in a twin screw extruder, to form pellets or granulates, or extruded and powdered. The fermented potato waste may be melt blended, for example by extrusion and injection moulded. In some embodiments, the fermented potato waste may be melt blended to form pellets/granulates or powder, which may be subsequently used for injection moulding. Such injection moulding may for example comprise injection moulding at temperatures of from 1 to 400 °C, for example from 100 to 200 °C, at pressures of from 1 to 1400 psi (0.07 to 97 bar), for example 800 to 1200 psi (55 to 83 bar), for example about 1000 psi (69 bar).

The heating and compression may also be conducted by rolling of the fermented potato waste into a sheet, for example by calendering using calendaring rollers at elevated temperatures and pressures. In this way, thin (around 1 mm to 1cm) flexible articles may be produced.

Where heating and compression are used, it has been found that a fermented potato waste mixture containing dried and micronized fermented potato flesh, dried and micronized starch and water in an approximate 1:1:1 ratio is preferred, although it will be appreciated that other ratios may be used.

The moulded article formed by the present method may be any suitably moulded shape.

Preferably, the moulded article is in the form of a board or panel. Such boards or panels may conveniently be substituted for traditional wood and resin based particle boards to provide a renewable and safer alternative. As will be appreciated, in some instances the moulded article may be further processed after being formed, for example by cutting or otherwise processing the moulded article to give a desired shape.

In some embodiments, the moulded article may be further processed to modify the surface of the article. For example, a waterproofing layer or coating may be added to the article or a veneer may be attached to the article to alter its surface appearance. A waterproofing coating may comprise one or more water resistant resins being applied to the surface of the moulded article. The moulded article may be mechanically processed, for example by further shaping the article and/or its surface, e.g. sanding the surface. By way of example, a moulded article may be processed by drum sanding the surface to a specific depth.

Although the present method has been described with reference to potato waste in particular, it will be appreciated that the method may be used with other organic waste such as other plant-based materials, for example including materials or waste derived from bamboo, wood, sugarcane, flax, hemp or brewers grain.

According to a further aspect, there is provided a moulded article produced by the method as defined previously herein.

Moulded articles produced by the methods described herein may provide sustainable and environmentally friendly articles that may be substituted for conventional materials, and may increase safety during production and processing afterwards by eliminating the need for toxic or carcinogenic chemicals.

A moulded article produced by the methods described herein may include an injection moulded article produced by melt blending the fermented potato waste from step (i). A moulded article produced by the methods described herein may also include materials produced by melt blending, for example by extrusion, of fermented potato waste to form a feedstock for injection moulding. Such materials may include pellets, granulates or powder.

According to a further aspect, there is provided an assembled or unassembled product comprising one or more moulded articles as defined previously herein.

In some embodiments, the assembled or unassembled product is an interior design product such as a furniture product.

According to a further aspect there is provided use of fermented organic waste, preferably fermented potato waste, to improve the mechanical properties of a moulded article.

Mechanical properties may include, for example, modulus, tensile strength, hardness, density, glass transition temperature, flexibility and/or toughness.

It will be appreciated that in relation to this aspect, the use may comprise preparing a moulded article by the method defined previously herein.

The present invention will now be illustrated by way of the following examples and with reference to Figures 1 and 2, in which: Figure 1 shows a flow diagram for a method of producing a fibreboard-type moulded article.

Figure 2 shows a flow diagram for a method of producing a bio-plastic-type moulded article.

With reference to the flow diagram in Figure 1, a method of producing a fibreboard-type moulded article is shown schematically. In step 101 potato waste is fermented to produce fermented potato waste. In step 102, the fermented potato waste is moulded into the desired shape, and in step 103 the moulded fermented potato waste is heated to form the moulded article.

With reference to the flow diagram in Figure 2, a method of producing a bio-plastic-type moulded article is shown schematically. In step 201 potato waste is fermented to produce fermented potato waste. In step 202, the fermented potato waste is moulded into the desired shape, and in step 103 the moulded fermented potato waste is simultaneously heated and compressed to form the moulded article.

Examples

Example 1: Procedure for preparing a moulded chip particle board Raw potato flesh chips are allowed to ferment for at least 12 days. The fermented chips are mechanically dewatered by straining through muslin cloth. Water runoff is collected and collected for use in the starch gelatinisation step. The dewatered chips are thermally desiccated for at least 12 hours and mechanically micronized by blending.

White potato starch (containing approximately 12% moisture) is allowed to ferment for at least 12 days. A sample of the fermented white starch is then thermally desiccated for 12 hours and mechanically micronized by blending. 20 g of the micronised starch is mixed with 80 g of water (collected from the aforementioned dewatering step) and heated at 60 °C for 15 minutes with constant agitation until a homogenous gel consistency is achieved.

100 g of the dried, micronized raw chips are mixed with 100 g of the gelatinized starch by blending (Mixture A). Additional dyes/pigments may be added as desired to this mixture.

Mixture A is then pre-formed to a desired thickness and heated between two plates, both heated to 240 °C for 15 minutes. The finished board is allowed to cure for at least 24 hours in the stainless-steel forming frame.

The procedure of Example 1 was also carried out with a pressing temperature of 100 °C, giving similar results.

Example 2: Procedure for preparing a chip strand board Raw potato flesh chips and potato peels are separately allowed to ferment for at least 12 days. The fermented peels and, if present, the fermented chips are separately mechanically dewatered by straining through muslin cloth. Water runoff is collected and collected for use in the starch gelatinisation step. The dewatered peels and, if present, the dewatered chips are separately thermally desiccated for at least 12 hours and mechanically micronized by blending.

White potato starch (containing approximately 12% moisture) is allowed to ferment for at least 12 days. A sample of the fermented white starch is then thermally desiccated for 12 hours and mechanically micronized by blending. 20 g of the micronised starch is mixed with 80 g of water (collected from the aforementioned dewatering step) and heated at 60 °C for minutes with constant agitation until a homogenous gel consistency is achieved.

g of the dried, micronized peels, or a 1:1 ratio of the dried micronised peels and the dried micronised chips, are mixed with 100g of the gelatinized starch by blending (Mixture B). Additional dyes/pigments may be added as desired to this mixture. Mixture B is then pre-formed to a desired thickness and heated between two plates, both heated to 240 °C for 15 minutes. The finished board is allowed to cure for at least 24 hours in the stainless-steel forming frame.

The procedure of Example 2 was also carried out with a pressing temperature of 100 °C, giving similar results.

Example 3: Procedure for preparing a moulded bio-plastic board Raw potato flesh chips are allowed to ferment for at least 12 days. The fermented chips are mechanically dewatered by straining through muslin cloth. The dewatered chips are thermally desiccated for at least 12 hours and mechanically micronized by blending.

White potato starch (containing approximately 12% moisture) is allowed to ferment for at least 12 days. A sample of the fermented white starch is then thermally desiccated for 12 hours and mechanically micronized by blending.

g of the dried, micronized chips are mixed with 100g of the dried, micronized white starch and 100m1 of water by blending (Mixture C). 200g of Mixture C is pressed at approximately 30 bar of pressure and 105 °C in a square mould for at least 30 minutes.

The pressed board is allowed to cure in a stainless steel forming mesh for at least 24 hours to form a translucent bio-plastic material that has an attractive surface finish and good durability.

The procedure of Example 3 was also carried out with a pressing temperature of 260 °C, giving similar results.

The fermentation products of Examples 1 to 3, were analysed before heating and moulding to determine the presence of various volatile fatty acids, and were found to contain lactic acid in an amount of from 7 to 31 g/L, formic acid in an amount of from 1 to 13 g/L, acetic acid in an amount of from 6 to 33.5 g/L, propionic acid in an amount of from 3 to 10 g/L, butyric acid in an amount of from 0.1 to 2 g/L, and hexanoic acid in an amount of from 0.01 to 1 g/L.

Claims

Claims 1. A method for producing a moulded article using potato waste, the method comprising: (i) fermenting the potato waste; (ii) moulding and heating the fermented potato waste from step (i) to form a moulded article.
2. A method according to Claim 1, wherein the fermentation step (i) is conducted for at least 48 hours, preferably at least 5 days, for example at least 8 days.
A method according to Claim 1 or Claim 2, wherein the potato waste is micronized prior to step (ii).
4. A method according to any one of the preceding claims, wherein moulding fermented potato waste comprises mechanically pressing the fermented potato waste.
5. A method according to any one of the preceding claims, wherein the moulded article is a board or panel.
A method according to any one of the preceding claims, wherein the heating is at a temperature of from 100 °C to 400 °C, optionally from 150 °C to 350 °C, for example from 200 °C to 300 °C.
7. A method according to Claim 6, wherein the heating step is conducted for at least 5 minutes, preferably at least 15 minutes, for example from 15 minutes to 2 hours.
A method according to any one of the preceding claims, wherein the moulded article is held in shape whilst cooling to ambient temperature following step (ii).
9. A method according to any one of the preceding claims, comprising mixing starch with the potato waste prior to moulding and heating in step (ii).
10. A method according to Claim 9, wherein the starch is potato starch. 35
11. A method according to Claim 9 or Claim 10, wherein the starch is added in an amount of from 5 wt.% to 40 wt.% as a proportion of the material used in step (ii).
12. A method according to any one of Claims 9 to 11, wherein the starch is gelatinised in water prior to mixing with the potato waste.
13. A method according to any one of the preceding claims, wherein the fermented potato waste used in step (ii) has a water content of from 10 wt.% to 50 wt.%, for example from 20 wt.% to 45 wt.%.
14. A method according to any one of the preceding claims, wherein step (U) comprises moulding the fermented potato waste and subsequently heating to form the moulded article.
15. A method according to any one of Claims 1 to 14, wherein step (ii) comprises simultaneously compressing and heating the fermented potato waste.
16. A method according to Claim 15, wherein the compression is at a pressure of from 1 bar to 40 bar.
17. A method according to Claim 15 or Claim 16, wherein step (ii) comprises melt blending and/or extruding the fermented potato waste.
18. A method according to any one of Claims 15 to 17, wherein step (ii) comprises melt blending the fermented potato waste and subsequently injection moulding the melt blended fermented potato waste.
19. A method according to any one of the preceding claims, wherein the potato waste used in step (i) comprises at least 20 wt.% starch by dry weight, for example at least 30 wt.% starch, for example at least 50 wt.% starch.
20. A method according to any one of the preceding claims, wherein the method comprises adding one or more filler materials to the to the potato waste, for example plant based fibres such as fibres derived from bamboo, wood, sugarcane, flax, hemp or brewers grain.
21. A moulded article produced by the method of any one of Claims 1 to 20.
22. An assembled or unassembled product comprising one or more moulded articles as defined in Claim 21.
23. The assembled or unassembled product of Claim 22, wherein the product is an interior design product, for example a furniture product.
24. Use of fermented potato waste to improve the mechanical properties of a moulded article.
25. Use according to Claim 24, wherein the moulded article is prepared by the method of any one of Claims 1 to 20.