WO2022071800A1 - Polymer composite comprising spent grains and/or grape pomace - Google Patents

Abstract

The invention concerns a polymer composite comprising: a. biodegradable polymer in an amount of 5-94.5% by weight of the overall weight; b. milled spent grains and/or milled grape pomace in an amount of at least 5% by weight of the overall weight; c. plasticizer in an amount from 5 – 50% w/w of component b); d. optional filler, and e. optional additive, wherein c) is a solid plasticizer with a melting temperature in the range of 70 to 210°. The invention also concerns a process for its preparation, an intermediate, and a solid article comprising the polymer composite.

Description

Title: Polymer composite comprising spent grains and/or grape pomace

Technical Field

This invention concerns a polymer composite comprising milled spent grains that are a byproduct of the brewing or distilling industry and/or milled grape pomace, a by-product of the wine industry. More in particular, this invention concerns a polymer composite comprising an increased amount of milled spent grains and/or milled grape pomace.

Background Art

Distillers’ grains are the cereal by-product of a fermentation or distillation process, whereas brewers’ grain, or brewer's spent grain (BSG), usually specifically refers to the residual barley (or in a mixture with other cereal grains or grain products) produced as a by-product of beer brewing, collected before fermentation of the wort. The majority of brewers’ grain comprises barley malt grain husks in combination with parts of the pericarp and seed coat layers of the barley. Distillers’ grains are normally a mix of corn, rice and other grains that have come from either brewing or the production of ethanol biofuels. For the purposes of this patent, the use of the term spent grains will encompass distillers’ grains and brewers’ grains.

Distillers’ grains are available as wet distillers grains (WDG), containing primarily unfermented grain residues (protein, fibre, fat and up to 70% moisture), and as dried distillers grains with solubles (DDGS), which is WDG that has been dried with the concentrated thin stillage to 10-12% moisture or less. DDGS is a complex composition of protein (26.8-33.7% dry weight basis) carbohydrates (39.2-61.9%), oils (3.5-12.8%), and ash (2.0-9.8%). The definition of spent grains refers to dried distillers’ grains and/or dried brewers’ spent grain that have optionally been further solvent treated to remove solubles and/or oils.

Pomace, or marc, is the name given to the solid remains of juice/oil-bearing fruits or vegetables following pressing for the removal of the juice/oil. Common fruits that are known to produce pomace include grape, olive, blackcurrant, orange, pineapple, and apple for example. Pomace normally comprises the skins, pulp, seeds, and stems of the fruit. Pomace can also be produced as a by-product of vegetable juice/oil processing, such as carrot and beetroot for example. Fruit pomace usually comprises 20-50% w/w of the original fruit mass whereas vegetable pomace normally comprises >30% w/w of the original vegetable mass.

Grape pomace from either white or red grapes represents about 20% of the total mass of the fruit and comprises skins, seeds, and any other solid remaining materials after the grape juice extraction through pressing. Products such as ethanol tartrates, citric acid, grape seed oii, hydrocolloids and dietary fibre can all be recovered from grape pomace. Protein content is between 11 - 16% w/w.

With the addition of an appropriate plasticizer, a chemical that is mixed with e.g. milled wheat distillers grains, with the purpose of preventing their inherent starch I protein chains from agglomerating, the plasticized powder can form a plastic composite with an appropriate polymer with high percentage of inclusion. The purpose of such is to either reduce fossil fuel based plastic content and/or create biodegradable I compostable composites with similar polymers.

It is known that DDGS has been compounded into polypropylene, polyethylene, acrylonitrile butadiene styrene, phenolic resins, polyurethane and polyamide up to 30% w/w loading levels, with and without the aid of compatibilizers.

It is similarly known that DDGS has been compounded into polylactic acid, polyhydroxyalkanoate, poly(butylene succinate), poly(butylene adipate-co-terephthalate), and blends thereof, up to 30% w/w loading levels, with and without the aid of compatibilizers and lubricants.

The use of DDGS, plasticized with either water or an aqueous solution of urea, is further covered in US patent 10,513,063 as a biomaterial for the preparation of injection moulded articles.

It is also known that DDGS is a feed source in the microbial production of D-lactic acid, which in turn is the precursor in the production of polylactic acid.

Compression thermoformed biocomposite boards made from a mixture of grape pomace (from both red and white wine grapes), soy flour, soy protein isolate, and poly(vinyl alcohol) (PVA) have been reported by Y. Jiang, J. Simonsen and Y. Zhao in “Compression-molded biocomposite boards from red and white wine grape pomaces”, Journal of Applied Polymer Science 2011 , 119, 2834-2846.

Melt extrusion and injection moulded biocomposites of poly(butylene succinate) (PBS) and grape pomace have similarly been reported both with and without the aid of maleic anhydride grafted PBS as compatabilizer by A. Gowman, T. Wang, A. Rodriguez-Uribe, A.K. Mohanty and M. Misra in “Bio-poly(butylene succinate) and Its Composites with Grape Pomace: Mechanical Performance and Thermal Properties”, ACS Omega 2018, 3, 15205- 15216.

Grape pomace extract has also been incorporated into starch films with nanocellulose by solvent casting methods by Y. Xu, A. Scales, K. Jordan, C. Kim and E. Sismour in “Starch nanocomposite films incorporating grape pomace extract and cellulose nanocrystal”, Journal of Applied Polymer Science 2017, DOI: 10.1002/APP.44438.

Red grape pomace (Vitis vinifera L., Merlot cultivar) comprising berry skins, seeds, petioles and stalks has been incorporated, by injection moulding techniques, into poly(3- hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolyester composites by

M. Ferri, M. Vannini, M. Ehrnell, L. Eliasson, E. Xanthakis, S. Monari, L. Sisti, P. Marchese, A. Celli and A. Tassoni in “From winery waste to bioactive compounds and new polymeric biocomposites: A contribution to the circular economy concept”, Journal of Advanced Research 2020, 24, 1-11, https://doi.Org/10.1016/j.jare.2020.02.015, and by G. David, M. Vannini, L. Sisti , P. Marchese, A. Celli, N. Gontard and H. Angellier-Coussy in “Eco- conversion of two winery lignocellulosic wastes into fillers for biocomposites: Vine shoots and wine pomaces”, Polymers 2020, 12, 1530, https://doi.org/10.3390/polym12071530.

Grape pomace has also been incorporated, by injecting moulding techniques, into polylactic acid (PLA) composites using maleic anhydride grafted PLA as a compatabilizer by A.

Gowman, A. Rodriguez-Uribe, F. Defersha, A.K. Mohanty and M. Misra in “Statistical design of sustainable composites from poly(lactic acid) and grape pomace”, Journal of Applied Polymer Science 2020, https://doi.org/10.1002/app.49061.

Furthermore, grape pomace was combined with pinewood residues to produce multicomponent composites in both high-density polyethylene and polypropylene matrices by C. Berger, B.D. Mattos, S.C. Amico, J. Antonio de Farias, R. Coldebella, D.A. Gatto, A.L. Missio in “Production of sustainable polymeric composites using grape pomace biomass”, Biomass Conversion and Biorefinery 2020, https://doi.org/10.1007/s13399-020-00966-w.

The purpose of the present invention is to find a solution that allows inclusion of greater amounts of milled spent grains, e.g. wheat distillers, and/or milled grape pomace without loss of strength or flexibility. Moreover, the purpose of the present invention is to find polymer composites that can be moulded, e.g., into disposable articles such as coffee capsules, cutlery, straws, drink stirrers, food trays, single-serve packaging, such as a cup, cap, container and/or lid, or any other single-use items, etc., i.e. with sufficient strength to form a disposable article with a wall thickness larger than 250 micrometres, whereas the polymer composites are biodegradable.

Summary of the Invention

A polymer composite is provided as claimed in claim 1 , comprising. a. biodegradable polymer in an amount of 5-94.5% by weight of the overall weight; b. milled spent grains and/or milled grape pomace in an amount of at least 5% by weight of the overall weight; c. plasticizer in an amount from 5 - 50% w/w of component b); d. optional filler, and e. optional additive, wherein c) is a solid plasticizer with a melting temperature in the range of 70 to 210°C.

Also provided is a process for preparing the polymer composite, an intermediate for preparing the polymer composite and articles comprising the polymer composite.

Detailed description of the Invention

It has been found that with the addition of at least 5%, preferably at least 15% by weight of a solid plasticizer based on the milled spent grains and/or milled grape pomace, optionally together with an appropriate filler, the milled spent grains and/or milled grape pomace can form a plastic composite material with a thermoplastic polymer even at high loading levels, e.g., higher than 40% w/w based on the milled spent grains and/or milled grape pomace and polymer, with sufficient strength to form a disposable article with a wall thickness larger than 250 micrometres (10 mils), and sufficient biodegradability.

For use in the present invention, any type of spent grains as defined above and/or grape pomace (from either white or red grapes) can be used as component b). This current invention specifically focusses on milled distillers’ grains based on any one or more of wheat distillers, barley distillers, maize distillers, and brewers’ grains, and/or milled grape pomace from either white or red grapes. Prior to compounding, the distillers’ grains and/or grape pomace are milled to a fine powder, having a particle size smaller than 1 mm, preferably smaller than 500 micrometres. This is preferably done in multiple stages to obtain a uniform small particle size. For instance, milled wheat distillers powder may be used. Similar considerations apply with respect to barley distillers, e.g., using milled barley distillers powder, maize distillers, e.g., milled maize distillers powder, brewers’ grains, e.g. milled brewers’ grains powder, or milled grape pomace, or combinations thereof. Milling is preferably carried out on dry material e.g. in order to more easily obtain a uniform small particle size and/or to reduce the amount of introduced liquid such as water. In an embodiment, materials may thus be dried prior to milling. Hence, although in this specification, materials may only be referred to as being milled, the present invention alternatively or additionally refers to embodiments in which the materials are dried milled and thus, if necessary, the wording “milled” may be replaced throughout the specification by the wording “dried milled” where appropriate. In other words, “milled” has to be interpreted as meaning “milled and/or dried milled” unless specifically stated otherwise.

The milled distillers’ grains and/or milled grape pomace may be used at low loading levels, starting at 5% by weight of the overall weight, but preferably is used at loading levels in excess of 20%, e.g., at loading levels of 20-90%, more preferably at loading levels of 20- 80%, still more preferably at loading levels of 20-70% by weight of the overall weight, or at loading levels in excess of 40%, e.g., at loading levels of 40 - 90%, more preferably at loading levels of 40 - 80%, still more preferably at loading levels of 40 - 70% by weight of the overall weight. The milled distillers’ grains and/or milled grape pomace may be mixed, e.g. up to 100%, preferably up to 50% by weight of component b), with milled expeller I meal I cake, milled pomace, milled biscuit meal (or biscuit cereal meal), coffee grounds, milled whole seeds, milled whole roots, milled whole beans, milled stems and/or leaves, whole grain flour of cereal grass, and flour of pulse, or combinations thereof. For instance, a mixture of two materials such as milled wheat distillers and either rapemeal, or evening primrose meal powder may be used. When mixing the milled distillers’ grains and/or milled grape pomace with expellers, meals, and the like, the amount of solid plasticizer can be calculated on either the weight of the milled distillers’ grains or milled grape pomace alone or the combined (total of the) mixture, dependent on the specific mixture.

Suitable expellers may include but are not limited to the expeller of sunflower seeds, rapeseed, linseed, peanut, palm fruit, sesame seed, castor seed, and sugar beet pulp. Suitable meals may include but are not limited to the meal of sunflower, borage, cottonseed, Buglossoides arvensis (Ahiflower), safflower, rosehip, canola, blackcurrant, palm kernel, rapemeal, and evening primrose. Biscuit meal, or biscuit cereal meal, may include either a mixture of or the individual components of the crumbed waste of cooked and processed biscuit, cake and cereal food products. Cereal grasses include staple crops such as maize, wheat, rice, barley, oat and millet and hybrids such as triticale, as well as feed for animals, such as canary seeds. Pulses include annual leguminous crops yielding from one to twelve grains or seeds of variable size, shape and colour within a pod, that are used for both food and feed and that are harvested solely for dry seed, such as field peas, faba beans and lupin beans. Suitable examples of pomace may include grape pomace, olive pomace, apple pomace, or the solid remains of other fruits or vegetables after pressing for juice or oil.

The biodegradable polymer may be mixed, e.g. up to 100%, preferably up to 50% by weight of component a), with any polymer. Suitable polymers to mix with the biodegradable polymer include synthetic and natural polymer, e.g., biobased and biodegradable polymers, but preferably a thermoplastic polymer is used.

The polymer composite may be made from any biodegradable polymer as component a), but preferably a thermoplastic polymer is used.

Suitable thermoplastic materials, either as biodegradable polymer or as polymer for mixing with the biodegradable polymer, include polyamides (such as nylon), acrylic polymers, polystyrenes, polypropylene (PP), polyethylene (including low-density polyethylene (LDPE) and high density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS), polyglycolic acid, polycarbonates, polybenzimidazole, poly ether sulphone, polyether ether ketones (PEEK), polyetherimide, polyphenylene oxide, polyphenylene sulphide, polyvinyl chloride, and polytetrafluoroethylene, or any suitable mixture thereof.

Elastomers, or combinations of thermoplastic polymers with elastomers may also be used. Suitable elastomers, either as biodegradable polymer or as polymer for mixing with the biodegradable polymer, include natural and synthetic rubbers, chloroprene, neoprene, isoprene, polybutadiene, butyl rubber, halogenated butyl rubber, styrene-butadiene, nitrile rubber, latex, fluoroelastomers, silicone rubbers, epichlorhydrin, poly ether block amides, ethylene vinyl acetate (EVA) and ethylene vinyl alcohol (EVOH) for example. The elastomer may comprise a thermoplastic elastomer, which may be selected from styrenic block copolymers (TPE-s), thermoplastic olefins (TPE-o), elastomeric alloys (TPE-v or TPV), thermoplastic polyurethanes (TPU), thermoplastic copolyester (TPE-E) and thermoplastic polyamides, for example.

Thermoset polymers, or combinations of thermoplastic polymers with thermoset polymers may also be used. Suitable thermoset polymers, either as biodegradable polymer or as polymer for mixing with the biodegradable polymer, include epoxy resins, melamine formaldehyde, polyester resins and urea formaldehyde, for example.

Suitable acrylic polymers (which may be thermoplastics, thermosets or thermoplastic elastomers) , either as biodegradable polymer or as polymer for mixing with the biodegradable polymer, include polyacrylic acid resins, polymethyl methacrylates, polymethyl acrylates, polyethyl acrylates, polyethyl ethacrylates, and polybutyl methacrylates, for example.

Suitable polyesters, either as biodegradable polymer or as polymer for mixing with the biodegradable polymer, include polyglycolide (PGA), polylactide or poly(lactic acid) (PLA), poly(lactide-co-glycolide) (PLGA), polycaprolactone (PCL), poly(butylene succinate) (PBS) and its copolymers, e.g. poly(butylene succinate-co-adipate) (PBSA), poly(butylene adipate- co-terephtalate) (PBAT), a linear copolymer of N-acetyl-glucosamine and N-glucosamine with p-1 ,4 linkage, cellulose acetate (CA), poly(hydroxybutyrate) (PHB) or other polyhydroxyalkanoates (PHA), poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), or any suitable mixture thereof. Most preferably either PLA or PBS is used as component a). Most preferably, for improved biodegradability, the polymer composite comprises either PLA or PBS in an amount between 30 - 50% w/w of the overall mixture.

Plasticizers are an important class of low molecular weight non-volatile compounds that are widely used in polymer industries as additives. Plasticizers for thermoplastics are, in general, high boiling point liquids, with average molecular weights of between 300 and 600, and linear or cyclic carbon chains (14 - 40 carbons). However, the purpose of the plasticizer for a biomaterial is to prevent agglomeration of the carbohydrate I protein chains so that the biomaterial mixes with the polymer and the two become a single plastic mass. For the purpose of the present invention, the plasticizer must be compatible with component b), and be different from component b).

The use of plasticizers is noted in US patent 2005/0101700 but the implication therein is that a plasticizer is added for the benefit of the overall biopolymer comprising both thermoactive material and fermentation solid. Similarly, in US patent 2018/0127554 the plasticizers mentioned and listed are specifically those used in polymers, specifically biodegradable polymers such as PLA. So too is the case in CN patent 109575540 where the plasticizers listed, apart from glycerin, are those specifically for use in PLA.

Whereas in the prior art the only example of a plasticizer associated with DDGS is in US patent 10,513,063, which is water or an aqueous solution of urea, the present invention requires the use of a solid plasticizer with a melting temperature in the range of 55 to 210 °C, preferably in the range of 70 to 210°C, more preferably in the range 80 to 210°C, and most preferably in the range 90 to 210°C. The plasticizer may be selected from polyols, polyfunctional alcohols, amphipolar plasticizers such as carboxylic acids and esters, for instance mono, di-, and tri-glyceride esters; mono-, di- and oligosaccharides and combinations thereof. Polyols have been found to be particularly effective. Suitable plasticizers include sorbitol, maltitol, sucralose, threitol, erythritol, psicose, allose, talose, ribitol, tagatose, arabinose, galactitol, lactitol, arabitol, glyceraldehyde, iditol, sorbose, ribose, galactose, volemitol, mannitol, fucitol, xylose, xylitol, trehalose, cellobiose, raffinose, glucose, mannose, fructose, isomalt, polydextrose and sucrose; and/or combinations thereof. For instance, xylose, with a melting point of 144 to 145°C and/or sorbitol, with a melting point of 94-96°C, and/or xylitol, with a melting point of 92-96°C may be used. An advantage of using sorbitol over xylose is the higher tensile strength of the resulting polymer composite. An advantage of using xylitol over sorbitol and xylose is the higher tensile strength of the resulting polymer composite. Further, xylitol has a lower solubility in water then sorbitol meaning that when the polymer composite is used in solid articles that during use are subjected to water, e.g., hot water, as in a drink stirrer, the chance of xylitol being dissolved into the water is lower.

Also, a mixture of a solid plasticizer and a liquid plasticizer may be used, provided the mixture has a melting temperature in the range of 55 to 210 °C, preferably in the range of 70 to 210°C, more preferably in the range 80 to 210°C, and most preferably in the range 90 to 210°C. The amount of liquid plasticizer is preferably small, e.g., up to 10% by weight of component c).

The plasticizer may be used in an amount from 15 - 50% w/w of component b), preferably between 22 - 40% w/w of component b).

Additional, optional components of the polymer composite include fillers, such as mineral fillers and/or natural fibres and/or carbon-based fillers.

Suitable mineral fillers include carbonates (including bicarbonates), phosphates, ferrocyanides, silica, silicates, aluminosilicates (including all forms of clay minerals, mica and talc), titanium dioxide, or combinations thereof. For instance, a nepheline syenite may be used or any similar filler derived from silica-undersaturated and peralkaline igneous rocks, as well as any type of bentonite.

Natural fibres include cellulose or lignocellulosic fibres such as plant or vegetable fibres from the blast, leaf, seed, wood, or stem. For instance, wood cellulose fibre may be used.

Carbon based fillers include carbon nanotubes (CNT), graphene, fullerene, graphite, and amorphous carbon.

The filler may be used in an amount from 0 - 96% w/w of the overall mixture, preferably between 1 - 40% w/w of the overall mixture. Optional additional components include compatibilizers, fragrances, heat and UV stabilizers, colouring agents and the like. Suitable compatibilizers include any acrylic grafted thermoplastics (for example: maleic anhydride grafted polyethylene, polypropylene, or polylactic acid), interface-active high-molecular-weight peroxides, poly(2-ethyl-2-oxazoline), any esters of citric acid, aromatic carbodiimides (for example: BioAdimide from Lanxess), wax-based emulsion additives (for example: Aquacer from BYK Additives), organo-silane coupling agents, and isocyanate (or diisocyanate) coupling agents (for example: methylenedi isocyanate).

The additional components may be used in an amount from 0 - 30% by weight of the overall mixture, preferably between 0 - 15% by weight of the overall mixture.

The polymer composite is made by so-called “hot compounding” techniques, where the components are combined under heat and shearing forces that bring about a state of molten plastic (fluxing) which is shaped into the desired product, cooled and allowed to develop ultimate properties of strength and integrity. Hot compounding includes calendering, extrusion, injection and compression moulding. This is carried out at temperatures, pressures and processing conditions specific to the selected polymer. For instance, when using PLA the temperature is preferably in the range of 130 to 215°C, more preferably in the range of 130 to 210°C, even more preferably in the range of 130 to 185°C, and most preferably between 130 to 165°C.

The polymer composite may also be made by a multistep process, wherein the milled spent grains and/or milled grape pomace is first compounded with the solid plasticizer and pelletized and the pellets or grinded pellets are then combined with the polymer. Additional components may be added in any of the steps of the multistep process. The present invention therefore also provides pellets or grinded pellets of milled spent grains and/or milled grape pomace compounded and pelletized with plasticizer and other components if any, as intermediate product for combination with the polymer to produce the polymer composite.

The result of the process can be in the form of a solid article (or layer or portion thereof) and may comprise a compounded pellet, extruded work-piece, injection-moulded article, blow moulded article, rota-moulded plastics article, two-part liquid moulded article, laminate, 3D printer filament, felt, woven fabric, knitted fabric, embroidered fabric, nonwoven fabric, geotextiles, fibres or a solid sheet, for example. The solid article may be in the form of a coffee capsule, cutlery, straw, drink stirrer, food tray, or single-serve packaging, such as a cup, cap, container and/or lid, or any other single-use item.

The solid article is preferably suited to be used and/or cleaned in water environments with a temperature above room temperature, preferably a temperature above 30°C, more preferably a temperature above 50°C, even more preferably a temperature above 60°C, and most preferably a temperature above 80°C. The solid article may for instance be used in a coffee machine using water at a temperature between 80 to 100°C, e.g., between 87 and 92°C.

The solid article is preferably suited to be used under pressure, e.g., a pressure above 2 bar, preferably a pressure above 4 bar, more preferably a pressure above 6 bar, and most preferably a pressure above 8 bar, e.g. as used in a coffee machine.

The solid article preferably has a minimum thickness above 250 micrometres, preferably above 350 micrometres, more preferably above 500 micrometres, and most preferably above 600 micrometres.

The invention is illustrated by the below examples.

Example 1

275 grams of PLA (Ingeo® 3251 D from Natureworks LLC), 225 grams of wheat distillers powder, dried for 6 hrs at 80°C before being milled in a laboratory grain mill grinder and sieved through a 1 mm sieve, and 67.5 grams of xylitol (sieved through a 1 mm sieve) were mixed in a sealed plastic bag into a homogenous mixture (Mixture 1).

Example 2

275 grams of Ingeo 3251 D PLA, 225 grams of barley distillers powder, dried for 6 hrs at 80°C before being milled in a laboratory grain mill grinder and sieved through a 1 mm sieve, and 67.5 grams of xylitol (sieved through a 1 mm sieve) were mixed in a sealed plastic bag into a homogenous mixture (Mixture 2).

Example 3

275 grams of Ingeo 3251 D PLA, 225 grams of maize distillers powder, dried for 6 hrs at 80°C before being milled in a laboratory grain mill grinder and sieved through a 1 mm sieve, and 67.5 grams of xylitol (sieved through a 1 mm sieve) were mixed in a sealed plastic bag into a homogenous mixture (Mixture 3). Example 4

275 grams of Ingeo 3251 D PLA, 225 grams of grape pomace powder, dried for 6 hrs at 80°C before being milled in a laboratory grain mill grinder and sieved through a 1 mm sieve, and 67.5 grams of xylitol (sieved through a 1 mm sieve) were mixed in a sealed plastic bag into a homogenous mixture (Mixture 4).

Example 5

150 grams of Ingeo 3251 D PLA, 192 grams of wheat distillers, dried for 6 hrs at 80°C before being milled in a laboratory grain mill grinder and sieved through a 1 mm sieve, 58 grams of xylitol (sieved through a 1 mm sieve) and 100 grams of HiFill™ N800 (nepheline syenite powder as inorganic filler from Sibelco UK Ltd) were mixed in a sealed plastic bag into a homogenous mixture (Mixture 5).

Example 6

150 grams of Ingeo 3251 D PLA, 192 grams of barley distillers powder, dried for 6 hrs at 80°C before being milled in a laboratory grain mill grinder and sieved through a 1 mm sieve, 58 grams of xylitol and 100 grams of Premium Quest™ Bentonite (calcium bentonite powder as inorganic filler from Amcol Minerals Europe Ltd) were mixed in a sealed plastic bag into a homogenous mixture (Mixture 6).

Example 7

10 kgs of wheat distillers grains were dried for 6 hrs at 80°C before being milled in a Magico EMC70 electric mill from AMA S.p.A. fitted with a 1 mm sieve. The resultant flour was then mixed with 30% by weight of xylitol in a tumble mixer to create a mixed powder of about 65 kgs weight. This mixture was then compounded with Ingeo 3251 D PLA in a ratio of 50:50 wheat disti llers/xylitol : PLA on a Werner and Pfleiderer ZSK 25 twin-screw compounder fitted with a ZS-B 25 twin-screw side feeder. The screw profile used is given in Table 1 along with the respective injection points for the component materials. The temperature settings along the barrel were 170, 190, 170, 170, 170, 170, 170, 170°C. The compounded filament was cooled in a water bath, dried under an air knife and pelletized using a SG-E 60 from Intelligent Pelletizing Solutions GmbH & Co KG. Pellets were dried overnight in a Dryplus 250 from Vismec s.r.l at 80°C. Table 1 Screw profile with material inclusion points

Conveying 16/16 (PLA)

36/36 (x 2)

36/18

36/36

36/18

Kneading 45/5/36

45/5/18

45/5/18 (x 2)

Conveying 36/36 (x 5) (wheat distillers/xylitol)

Kneading 45/5/36 (x 3)

Conveying 36/36

Kneading 45/5/24 (x 3)

Conveying 16/16

36/36 (x 2)

Kneading 45/5/12 (x 2)

90/5/24

Conveying 36/36

Kneading 45/5/12 (x 2)

45/5/12

Conveying 36/36 (x 5)

24/24 (x 4)

Example 8

10 kgs of grape pomace was dried for 6 hrs at 80°C before being milled in a Magico EMC70 electric mill from AMA S.p.A. fitted with a 1 mm sieve. The resultant powder was then mixed with 30% by weight of xylitol in a tumble mixer to create a mixed powder of about 65 kgs weight. This mixture was then compounded with Ingeo 3251 D PLA in a ratio of 50:50 grape pomace/xylitokPLA on a Werner and Pfleiderer ZSK 25 twin-screw compounder fitted with a ZS-B 25 twin-screw side feeder. The screw profile used is given in Table 1 and the respective injection points for the component materials were as per Example 7. All other details were as per Example 7.

Examples 9 - 16

Mixtures 1 - 6 (from Examples 1 - 6) and compounded pellets from Examples 7 and 8 were individually poured into the hopper of a Negri Bossi v55 injection moulding machine with a 32 mm diameter screw and a L/D ratio of 20:1 operating at temperatures ranging from 130 to 185°C. Each molten plasticized mixture was injection moulded in a twin-cavity tool fitted with a single-drop hotrunner system into drink stirrer sticks suitable for stirring beverages.

Examples 17 - 18

Compounded pellets from Examples 7 and 8 were individually poured into the hopper of a Negri Bossi v55 injection moulding machine with a 32 mm diameter screw and a L/D ratio of 20:1 operating at temperatures ranging from 130 to 185°C. Each molten plasticized mixture was injection moulded in a single-cavity tool fitted with a single-drop coldrunner system into a three-step plaque with each step measuring 25 x 25 mm and thicknesses of 0.75 mm, 1 .0 mm, and 1.50 mm.

Examples 19 - 20

Twenty plaques of dimensions 25 x 25 x 0.75 mm (weight: 0.86 ± 0.01 g and 0.85 ± 0.01 g) from Examples 17 and 18 respectively were mixed into 2 kgs of commercially purchased topsoil (passed through a 4 mm sieve) containing enough distilled water to saturate (defined by not leaving any standing water) the soil in a 5 L Pyrex glass beaker covered with 20 cm diameter watch glass. The beaker was placed inside a Unitemp temperature controlled oven set at 58°C (as per the thermophilic incubation period as detailed in IS020200-2015). The trial was left undisturbed for separate periods of 21 days up to a total of 90 days.

Upon extraction and cooling to room temperature of the glass beaker at the end of each 21 day trial period, the soil was carefully broken apart to extract any intact plaques. Following extraction of both plaques and the larger pieces of broken plaques the soil was again sifted through a 4 mm sieve to extract any remaining pieces. All plaques were dried and then carefully brushed with a toothbrush to remove any attached dirt before being examined and returned to re-saturated soil for another 21 day trial period until the end of the 90 day trial period. At the end of the 90 day trial period all plaques of both Examples had disintegrated into pieces with less than 15% by weight not passing through a 4 mm sieve.

Summary

Examples 1 - 4, 7 and 8 illustrate polymer composites with a high loading of distillers dried grain powder and/or grape pomace powder. In Examples 5 and 6 the combination of distillers dried grain powder with inorganic filler materials have been used have been used.

All formulations allowed the preparation of a disposable article, in this case a drink stirrer. Plaques made from wheat distillers grains and also grape pomace proved to be highly biodegradable, as shown in Examples 19 and 20 respectively. The invention can be summarized by the following clauses:

1. Polymer composite comprising: a. polymer in an amount of 5-94.5% by weight of the overall weight; b. milled spent grains, in an amount of at least 5% by weight of the overall weight; c. plasticizer in an amount from 5 - 50% w/w of component b); d. optional filler, and e. optional additive, wherein c) is a solid plasticizer with a melting temperature in the range of 55 to 210°C.

2. Polymer composite as claimed in clause 1 , wherein component a) comprises a biodegradable polymer, preferably PLA, or derivatives or polymer blends thereof.

3. Polymer composite as claimed in clause 2, wherein component a) is present in an amount of 30-70% by weight of the overall weight, preferably in an amount of 30-50% by weight of the overall weight.

4. Polymer composite as claimed in any of the preceding clauses, wherein component b) comprises milled wheat distillers, or milled barley distillers, or milled maize distillers, or milled brewers’ grains, or a mixture thereof.

5. Polymer composite as claimed in any of the preceding clauses, comprising a mixture of milled spent grains and up to 50% w/w of component b) of milled expeller I meal I cake, milled pomace, milled biscuit meal or individual components thereof, milled whole seeds, milled whole roots, milled whole beans, milled stems and/or leaves, milled whole grain flour of cereal grass, flour of pulse, or a mixture thereof.

6. Polymer composite as claimed in any of the preceding clauses, wherein component b) or the mixture of clause 5 is present in an amount of 30 - 70% by weight of the overall weight.

7. Polymer composite as claimed in any of the preceding clauses, comprising polyols, polyfunctional alcohols, amphipolar plasticizers such as carboxylic acids and esters, for instance mono, di-, and tri-glyceride esters; mono-, di- and oligosaccharides, or mixtures thereof, as component c).

8. Polymer composite as claimed in any of the preceding clauses, wherein component c) is present in an amount from 22 to 40% w/w of component b).

9. Polymer composite as claimed in any of the preceding clauses, comprising as component d) either a natural fibre, preferably cellulose or lignocellulose fibres, and/or a mineral filler preferably selected from carbonates (including bicarbonates), phosphates, ferrocyanides, silica, silicates, aluminosilicates (including all forms of clay minerals and talc), titanium dioxide, and/or a carbon-based filler, or combinations thereof.

10. Polymer composite as claimed in any of the preceding clauses, wherein component d) is present in an amount from 1 - 40% by weight of the overall weight.

11. Polymer composite as claimed in any of the preceding clauses, comprising compatibilizers, fragrances, heat and UV stabilizers, and/or colouring agents or a mixture thereof as additive.

12. A process for preparing the polymer composite as claimed in any of the preceding clauses, wherein the polymer composite is made by hot compounding techniques, where the components are combined under heat and shearing forces that bring about a state of molten plastic (fluxing) which is shaped into the desired product, cooled and allowed to develop ultimate properties of strength and integrity, preferably by calendering, extrusion, injection and compression moulding.

13. The process of the preceding clause, carried out at temperatures in the range of 130 to 210°C.

14. The process of clause 12 or 13, carried out in two steps, forming an intermediate first in a first step and combining the intermediate with the remainder of the components in a second step.

15. A solid article comprising the polymer composite as claimed in any of the preceding clauses 1-11.

16. The solid article of the preceding clause, in the form of a compounded pellet, extruded work-piece, injection-moulded article, blow moulded article, film or rota- moulded plastic article, two-part liquid moulded article, laminate, 3D printer filament, felt, woven fabric, knitted fabric, embroidered fabric, nonwoven fabric, geotextiles, fibre or a solid sheet.

17. The solid article of clause 15 or 16, in the form of a coffee pod, cutlery, food tray, or single-serve packaging.

18. An intermediate as prepared by the process of clause 14, for use in the preparation of a polymer composite as claimed in any of the preceding clauses 1-11.

19. Polymer composite comprising: f. polymer in an amount of 5-94.5% by weight of the overall weight; g. milled pomace, in an amount of at least 5% by weight of the overall weight; h. plasticizer in an amount from 5 - 50% w/w of component b); i. optional filler, and j. optional additive, wherein c) is a solid plasticizer with a melting temperature in the range of 55 to 210°C. 20. Polymer composite as claimed in clause 19, wherein component a) comprises a biodegradable polymer, preferably PLA, or derivatives or polymer blends thereof.

21. Polymer composite as claimed in clause 20, wherein component a) is present in an amount of 30-70% by weight of the overall weight, preferably in an amount of 30-50% by weight of the overall weight.

22. Polymer composite as claimed in any of the preceding clauses 19-21, wherein component b) comprises milled apple pomace, or milled grape pomace, or milled olive pomace, or milled carrot pomace, or a mixture thereof.

23. Polymer composite as claimed in any of the preceding clauses 19-22, comprising a mixture of milled pomace and up to 50% w/w of component b) of milled expeller I meal I cake, milled distillers’ grain, milled brewer’s grain (or brewer’s spent grain I draff), milled biscuit meal or individual components thereof, milled whole seeds, milled whole roots, milled whole beans, milled stems and/or leaves, milled whole grain flour of cereal grass, flour of pulse, or a mixture thereof.

24. Polymer composite as claimed in any of the preceding clauses 19-23, wherein component b) or the mixture of clause 23 is present in an amount of 30 - 70% by weight of the overall weight.

25. Polymer composite as claimed in any of the preceding clauses 19-24, comprising polyols, polyfunctional alcohols, amphipolar plasticizers such as carboxylic acids and esters, for instance mono, di-, and tri-glyceride esters; mono-, di- and oligosaccharides, or mixtures thereof, as component c).

26. Polymer composite as claimed in any of the preceding clauses 19-25, wherein component c) is present in an amount from 22 to 40% w/w of component b).

27. Polymer composite as claimed in any of the preceding clauses 19-26, comprising as component d) either a natural fibre, preferably cellulose or lignocellulose fibres, and/or a mineral filler preferably selected from carbonates (including bicarbonates), phosphates, ferrocyanides, silica, silicates, aluminosilicates (including all forms of clay minerals and talc), titanium dioxide, and/or a carbon-based filler, or combinations thereof.

28. Polymer composite as claimed in any of the preceding clauses 19-27, wherein component d) is present in an amount from 1 - 40% by weight of the overall weight.

29. Polymer composite as claimed in any of the preceding clauses 19-28, comprising compatibilizers, fragrances, heat and UV stabilizers, and/or colouring agents or a mixture thereof as additive.

30. A process for preparing the polymer composite as claimed in any of the preceding clauses 19-29, wherein the polymer composite is made by hot compounding techniques, where the components are combined under heat and shearing forces that bring about a state of molten plastic (fluxing) which is shaped into the desired product, cooled and allowed to develop ultimate properties of strength and integrity, preferably by calendering, extrusion, injection and compression moulding. The process of the preceding clause, carried out at temperatures in the range of 130 to 210°C. The process of clause 12 or 13, carried out in two steps, forming an intermediate first in a first step and combining the intermediate with the remainder of the components in a second step. A solid article comprising the polymer composite as claimed in any of the preceding clauses 19-30. The solid article of the preceding clause, in the form of a compounded pellet, extruded work-piece, injection-moulded article, blow moulded article, film or rota- moulded plastic article, two-part liquid moulded article, laminate, 3D printer filament, felt, woven fabric, knitted fabric, embroidered fabric, nonwoven fabric, geotextiles, fibre or a solid sheet. The solid article of clause 15 or 16, in the form of a coffee pod, cutlery, food tray, or single-serve packaging. An intermediate as prepared by the process of clause 14, for use in the preparation of a polymer composite as claimed in any of the preceding clauses 19-30.

Claims

1. Polymer composite comprising: a. biodegradable polymer in an amount of 5-94.5% by weight of the overall weight; b. milled spent grains or milled grape pomace, in an amount of at least 5% by weight of the overall weight; c. plasticizer in an amount from 5 - 50% w/w of component b); d. optional filler, and e. optional additive, wherein c) is a solid plasticizer with a melting temperature in the range of 70 to 210°C.

2. Polymer composite as claimed in claim 1 , wherein component a) comprises a biodegradable polymer, preferably polyglycolide (PGA), polylactide or poly(lactic acid) (PLA), poly(lactide-co-glycolide) (PLGA), polycaprolactone (PCL), poly(butylene succinate) (PBS) and its copolymers, e.g. poly(butylene succinate-co-adipate) (PBSA), poly(butylene adipate-co-terephtalate) (PBAT), a linear copolymer of N- acetyl-glucosamine and N-glucosamine with p-1 ,4 linkage, cellulose acetate (CA), poly(hydroxybutyrate) (PHB) or other polyhydroxyalkanoates (PHA), poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), or any suitable mixture thereof, or derivatives or polymer blends thereof.

3. Polymer composite as claimed in claim 1 or 2, wherein component a) is present in an amount of 30-70% by weight of the overall weight, preferably in an amount of 30-50% by weight of the overall weight.

4. Polymer composite as claimed in any of the preceding claims, wherein component b) comprises milled wheat distillers, or milled barley distillers, or milled maize distillers, or milled brewers’ grains, or milled grape pomace, or a mixture thereof.

5. Polymer composite as claimed in any of the preceding claims, comprising a mixture of milled spent grains and up to 100% w/w of component b) of milled expeller I meal I cake, milled pomace, milled biscuit cereal meal or individual components thereof, coffee grounds, milled whole seeds, milled whole roots, milled whole beans, milled stems and/or leaves, milled whole grain flour of cereal grass, flour of pulse, or a mixture thereof.

6. Polymer composite as claimed in any of the preceding claims, wherein component b) or the mixture of claim 5 is present in an amount of 20 - 70% by weight of the overall weight.

7. Polymer composite as claimed in any of the preceding claims, comprising polyols, polyfunctional alcohols, amphipolar plasticizers such as carboxylic acids and esters, for instance mono, di-, and tri-glyceride esters; mono-, di- and oligosaccharides, or mixtures thereof, as component c).

8. Polymer composite as claimed in any of the preceding claims, wherein component c) is present in an amount from 22 - 40% w/w of component b).

9. Polymer composite as claimed in any of the preceding claims, comprising as component d) either a natural fibre, preferably cellulose or lignocellulose fibres, and/or a mineral filler preferably selected from carbonates (including bicarbonates), phosphates, ferrocyanides, silica, silicates, aluminosilicates (including all forms of clay minerals, mica and talc), titanium dioxide, and/or a carbon-based filler, or combinations thereof.

10. Polymer composite as claimed in any of the preceding claims, wherein component d) is present in an amount from 1 - 40% by weight of the overall weight.

11. Polymer composite as claimed in any of the preceding claims, comprising compatibilizers, fragrances, heat and UV stabilizers, and/or colouring agents or a mixture thereof as additive.

12. A process for preparing the polymer composite as claimed in any of the preceding claims, wherein the polymer composite is made by hot compounding techniques, where the components are combined under heat and shearing forces that bring about a state of molten plastic (fluxing) which is shaped into the desired product, cooled and allowed to develop ultimate properties of strength and integrity, preferably by calendering, extrusion, injection and compression moulding.

13. The process of the preceding claim, carried out at temperatures in the range of 130 to 215°C.

14. The process of claim 12 or 13, carried out in two steps, forming an intermediate first in a first step and combining the intermediate with the remainder of the components in a second step.

15. A solid article comprising the polymer composite as claimed in any of the preceding claims 1-11.

16. The solid article of the preceding claim, in the form of a compounded pellet, extruded work-piece, injection-moulded article, blow moulded article, rota-moulded plastic article, two-part liquid moulded article, laminate, 3D printer filament, felt, woven fabric, knitted fabric, embroidered fabric, nonwoven fabric, geotextiles, fibre or a solid sheet.

17. The solid article of claim 15 or 16, in the form of a coffee capsule, cutlery, straw, drink stirrer, food tray, or single-serve packaging, such as a cup, cap, container and/or lid, or any other single-use item.

18. An intermediate as prepared by the process of claim 14, for use in the preparation of a polymer composite as claimed in any of the preceding claims 1-11.