NL2026592B1 - Polymer composite comprising areca catechu - Google Patents

Abstract

The invention concerns a polymer composite comprising: a. polymer in an amount of 5-94.5% by weight of the overall weight; b. areca catechu powder 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. The invention also concerns a process for its preparation, an intermediate, and a solid article comprising the polymer composite.

Description

Title: Polymer composite comprising areca catechu Technical Field This invention concerns a polymer composite comprising areca catechu. More in particular, this invention concerns a polymer composite comprising an increased amount of areca catechu. Background Art Areacaceae are common trees in e.g. India. The betel palm tree Areca catechu has 7 -12 leaves per stem which fall by nature four times per year. The leaves are collected in forestry environments or by farmers who grow the betel nut at plantations. The leaves are used e.g. as reinforcement materials but are mostly regarded as waste and burned. The term 'leaf sheath' is known in the art, and refers to that part of the leaf, that is in contact with the stem of the tree, extending to the annular joint where the leaf is joined to the tree. When the tree loses its leaves, the sheath loses contact with the stem. The sheath part can e.g. be manually separated from the leaf part. The term 'leaf sheath derived material’ is to be understood to include a particulate of the leaf sheaths, e.g. obtained by grinding, which particulate can be further processed e.g. into pellets, as will be discussed below.

The use of areca catechu is described in WO2014/084724. Polymer composites, wherein the thermoplastic polymer is chosen from the group consisting of PLA, PHA, PP, PET, PVC, PS, PC, PV, ABS or a mixture of two or more thereof, are claimed. The thermoplastic polymer preferably comprises poly(lactic acid), PLA. By blending the leaf sheath material as first component with e.g. polylactic acid, polymeric articles can be obtained that are biodegradable under natural circumstances, therewith avoiding the need for industrial installations with high temperature and high humidity treatment of polylactic acid for decomposition. By blending the polylactic acid with the leaf sheath material, the polymer material can easily be decomposed at low costs. Home decomposition and traditional landfill is now possible, and because of the relatively high hemicellulose and lignin content, the polymer is very suitable for biogas formation. Moreover, blending non-biodegradable matrix components, such as PP, PET, etc., with the leaf sheath material as first matrix component as defined above, results in a polymer blend of equal or similar quality as compared with the corresponding polymer material without the said first matrix component. Interestingly, it has been observed that blending the first matrix component with non-biodegradable polymers such as polypropylene, a novel polymer material is obtained where the former non-biodegradable polymers acquire biodegradability.

2.

In WO2014/084724 the leaf sheath material is fully molten and processed as a common polymer, i.e. be subjected to extrusion, injection moulding etc. In case a second or additional polymer matrix material is present, the temperature is preferably chosen such, that the polymer matrix components form a uniform melt wherein all matrix components are molten. The temperature of the melt is preferably 250°C or less, preferably 230°C or less, in order to avoid burning of the polymeric melt. However, the optimal temperature range is dictated by the ratio and composition of matrix components, as the skilled person will readily understand.

The said melt is then further processed e.g. by extrusion of injection moulding or any other suitable moulding technique. If present, the second or any additional polymer matrix material is preferably melted together with the fist polymeric matrix material (i.e. the leaf sheath material).

It has surprisingly been found that the use of such a matrix component results in advantageous polymeric material that has form stability and is biodegradable under normal natural conditions according to ASTM D6954-01/04 guidelines. Still, for some applications, like disposable articles such as coffee capsules, cutlery, food trays, single-serve packaging etc. further improvement by increasing the inclusion levels of areca catechu is highly desirable.

The purpose of the present invention is to find a solution that allows inclusion of greater amounts of areca catechu, without melt processing and product stability issues. Increasing the inclusion levels is desirable to reduce fossil fuel based plastic content and may help to create biodegradable / compostable polymer composites with properties similar to common thermoplastics.

Summary of the Invention A polymer composite is provided as claimed in claim 1, comprising: a. polymer in an amount of 5-94.5% by weight of the overall weight; b. areca catechu powder 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.

23.

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 solid plasticizer, i.e., not water or glycerol as used in WO2014/084742, areca catechu can form even better plastic composite materials with a thermoplastic polymer at loading levels, higher than 40% w/w based on the areca catechu and polymer.

Areca catechu powder as defined in WO2014/084742 (the content of which is included herein by reference) may be used. The powder may be obtained by cutting the leaves including both the dark-coloured leaf and the pale whitish leaf sheath. The leaf sheaths may be collected, dried and grinded/milled for instance to a particle size of 3-4 mm, preferably a maximum particle size of 2 mm, more preferably a maximum particle size of 1 mm, and most preferably a maximum particle size of 500 micrometres. Milling may be done in multiple stages to obtain a uniform small particle size.

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 areca catechu powder may be used at low loading levels, starting at 5% w/w on the combination of components a) and b), but preferably is used at loading levels in excess of 20% wiw, e.g., at loading levels of 20-90% w/w, more preferably at loading levels of 20-80%, still more preferably at loading levels of 20-70% w/w. The areca catechu powder may be mixed, preferably up to 50% by weight of component b), with milled expeller / meal / cake, milled pomace, milled distillers’ grain, milled brewer's grain (or brewer’s spent grain / draff), milled biscuit meal (or biscuit cereal meal), milled whole seeds, milled whole roots, milled whole beans, milled stems and/or leaves, flour of pulse, and whole grain flour of cereal grass, or combinations thereof. For instance, a mixture of two materials such as areca catechu powder and either borage meal, or canary seed powder may be used. When mixing the areca

-4- catechu powder with expellers, meals, and the like, the amount of plasticizer is calculated on the combined (total) weight of the areca catechu powder 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, 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 polymer composite may be made from any polymer as component a), but preferably a thermoplastic polymer is used. Suitable polymers include synthetic and natural polymers, e.g. biobased and biodegradable polymers. Suitable thermoplastic materials include polyamides (such as nylon), acrylic polymers, polystyrenes, polypropylene, 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 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-0), elastomeric alloys (TPE-v or TPV), thermoplastic polyurethanes (TPU), thermoplastic copolyester (TPE-E) and thermoplastic polyamides, for example.

-5. Thermoset polymers, or combinations of thermoplastic polymers with thermoset polymers may also be used. Suitable thermoset polymers include epoxy resins, melamine formaldehyde, polyester resins and urea formaldehyde, for example.

Suitable acrylic polymers (which may be thermoplastics, thermosets or thermoplastic elastomers) include polyacrylic acid resins, polymethyl methacrylates, polymethyl acrylates, polyethyl acrylates, polyethyl ethacrylates, and polybutyl methacrylates, for example. Suitable polyesters include polyglycolide (PGA), polylactide or poly(lactic acid) (PLA), poly(lactide-co-glycolide) (PLGA), polycaprolactone (PCL), poly(butylene succinate) (PBS) and its copolymers, poly(butylene adipate-co-terephtalate) (PBAT), a linear copolymer of N- acetyl-glucosamine and N-glucosamine with B-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 PLA is used as component a). Most preferably, for improved biodegradability, the polymer composite comprises PLA in an amount between 30 to 50% w/w of the overall mixture.

To avoid degradation of the areca catechu powder or mixture thereof, preferably a polymer is used which may be processed at a temperature up to 210°C, preferably up to 180°C 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 / 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 c} must be compatible with component b), and be different from component b).

The plasticizer may be liquid or solid or a combination thereof. Preferably it is a solid plasticizer, more preferably selected from polyols, polyfunctional alcohols, amphipolar plasticizers such as carboxylic acids and esters, for instance mong, di-, and tri-glyceride esters; mono-, di- and oligosaccharides and combinations thereof. Polyols have been found to be particularly effective. Suitable plasticizers include water, glycerol, ethylene bisformamide, urea, citric acid, citrate/lipid mixtures, galactose, adipic acid, fructose, trimethylolpropane, urea, tartaric acid, xylose, xylitol, ethyleneglycol, triethyleneglycol (TEG), tetraethyleneglycol (TEEG), triethanolamine, ethanolamine, diethanolamine, sorbitol, maltitol,

-6- 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. The present invention may require the use of a solid plasticizer or a mixture of a solid plasticizer and a liquid plasticizer, e.g. with a melting temperature in the range of 55-210 °C. The amount of liquid plasticizer may be 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 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 compatibilisers, fragrances, heat and UV stabilizers, colouring agents and the like. Suitable compatibilisers include any acrylic grafted thermoplastics (for example: maleic anhydride grafted polyethylene, polypropylene, or polylactic acid), interface-active high-molecularweight peroxides, poly{2-ethyl-2-cxazoline), any esters of citric acid, aromatic carbodiimides {for example: DioAdimide from Lanxess), wax-based emulsion additives (for example: Aquacer from BYK Additives), organo-silane coupling agents, and isoovanaie (or diisoovanale; coupiing agents (for example: methylenedisocyanate).

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.

-7- 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 210°C, preferably between 130 to 165°C. The polymer composite may also be made by a multistep process, wherein the areca catechu powder 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 areca catechu powder 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, film or rota-moulded plastics article, two-part liquid moulded article, laminate, 3D printer filament, felt, woven fabric, knitted fabric, embroidered fabric, unwoven fabric, geotextiles, fibres or a solid sheet, for example.

The solid article may be in the form of a coffee pod, cutlery, food tray, or single-serve packaging.

The invention is illustrated by the below examples.

Example 1 275 grams of PLA (Ingeo® 3251D from Natureworks LLC), 225 grams of milled areca catechu and 67.5 grams of xylose was mixed in a sealed plastic bag into a homogenous mixture. This mixture was then poured into the hopper of a Negri Bossi v55 injection moulding machine with a 32 mm diameter screw operating at temperatures ranging from 130 to 165°C. The mixture was moulded into coffee capsules suitable for use in a Nespresso® coffee machine.

-8- Example 2 275 grams of PLA (Ingeo 3251D from Natureworks LLC), 225 grams of milled areca catechu and 67.5 grams of sorbitol was mixed in a sealed plastic bag into a homogenous mixture. This mixture was then poured into the hopper of a Negri Bossi v55 injection moulding machine with a 32 mm diameter screw operating at temperatures ranging from 130 to 165°C.

The mixture was moulded into coffee capsules suitable for use in a Nespresso coffee machine. Example 3 275 grams of PLA (Ingeo 3251D from Natureworks LLC), 225 grams of milled areca catechu powder, 67.5 grams of xylose and 100 grams of Premium Quest™ Bentonite (calcium bentonite powder as inorganic filler from Amcol Minerals Europe Ltd) was mixed in a sealed plastic bag into a homogenous mixture. This mixture was then 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 165°C. The mixture was moulded into coffee capsules suitable for use in a Nespresso coffee machine. Example 4 Representative coffee capsules from examples 1-3 were filled to level capacity with ground coffee grains and sealed with self-sealing aluminium coffee capsule lids. Filled pods were then tested in a standard Nespresso coffee machine to produce a volume of filtered coffee. All capsules tested produced approximately the same volume of coffee as expelled from a commercial Nespresso capsule.

Example 5 Fifteen representative coffee capsules from example 1 (weight: 2.50 + 0.01 g) were mixed into 2 kgs of natural topsoil containing 1 kg of distilled water in a 5 L Pyrex glass beaker and then covered with 20 cm diameter watch glass. The beaker was placed inside a Unitemp temperature-controlled oven set at 58°C and left for 21 days. Upon completion of the time the soil was removed from the beaker and broken up in order to examine the disintegration, if any, of the capsules. The remains of all 15 pods could be identified with five pods essentially remaining intact, with cracking and minor damage to the pod rim. All other remains comprised pieces of pods, up to about 75% intact. All pieces that could be extracted from the soil were too fragile to remove any attached soil and could therefore not be cleaned and weighed.

-9- Summary Examples 1 and 2 illustrate polymer composites with a high loading of areca catechu. In Example 3 the combination of areca catechu with an inorganic filler is illustrated.

All three formulations allowed the preparation of a disposable article, in this case a coffee capsule. The coffee capsules were strong enough to be used in a Nespresso® coffee machine, as shown in Example 4. Moreover, the coffee capsules proved to be highly biodegradable, as shown in Example 5.

Claims (17)

-10 - CONCLUSIONS A polymer composite comprising: a. polymer in an amount of 5-94.5 wt. % of the total weight; b. betel palm powder, in an amount of at least 5 wt. % of the total weight; c. plasticizer in an amount of 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 55-210°C. Polymer composite according to claim 1, wherein component a) is a biodegradable polymer, preferably PLA, or derivatives. or polymer mixtures thereof. The polymer composite of claim 2, wherein component a) is present in an amount of 30-70 wt. % of the total weight, preferably in an amount of 30-50 wt. % of the total weight. Polymer composite according to any one of the preceding claims, comprising a mixture of betel palm powder and up to 50% w/w of component b) of milled press residue / flour / cake, milled pulp, milled distiller's grain, milled brewer's grain (or spent beer), milled biscuit flour or individual components thereof, ground whole seeds, ground whole roots, ground whole beans, ground stalks and/or leaves, ground wholemeal cereal grass meal, pod meal or a mixture thereof. A polymer composite according to any one of the preceding claims, wherein component b) or the mixture according to claim 4 is present in an amount of 30-70 wt. % of the total weight. A polymer composite according to any one of the preceding claims comprising polyols, polyfunctional alcohols, amphipolar plasticizers such as carboxylic acids and esters, for example mono-, di- and triglyceride esters; mono-, di- and oligosaccharides, or mixtures thereof, as component c). A polymer composite according to any one of the preceding claims, wherein component c) is present in an amount of 22 to 40% w/w of component b). Polymer composite according to any one 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 and talc), titanium dioxide and/or a carbon-based filler, or combinations thereof. -11 - A polymer composite according to any one of the preceding claims, wherein component d) is present in an amount of 1-40 wt. % of the total weight. A polymer composite according to any one of the preceding claims, collapsing compatibilizers, fragrances, heat and UV stimulants and/or dyes or a mixture thereof as an additive. A process for preparing the polymer composite according to any one of the preceding claims, wherein the polymer composite is made by means of hot compounding techniques, wherein the components are compounded under heat and shear forces which create a state of molten plastic (fluxan) leading to the desired product is formed, cooled and allowed to develop ultimate properties of strength and integrity, preferably by calendering, extrusion, injection and press fermentation. The method according to the preceding claim, carried out at temperatures in the range of 130 to 210°C. The method of claim 11 or 12, performed in two steps, wherein an intermediate is first formed in a first step and the intermediate is combined with the remainder of the components in a second step. A solid article comprising the polymer composite of any one of claims 1-10. The solid article of the preceding claim, in the form of a composite pellet, extruded workpiece, injection molded article, blow molded article, film or rotomoulded plastic article, two piece liquid molded article, laminate, 3D printer filament, felt, woven fabric, knitted fabric , embroidered fabric, non-woven fabric, geotextile, fiber or a solid board. The solid article according to claim 14 or 15, in the form of a coffee capsule, cutlery, food bowl or disposable container. An intermediate as prepared by the process according to claim 13, for use in the preparation of a polymer composite according to any one of the preceding claims 1 10.