EP2247660A2 - Method for preparing thermoplastic compositions based on plasticized starch and resulting compositions - Google Patents

Abstract

The subject matter of the present invention is a method for preparing a starch-based thermoplastic composition, comprising the following steps: (a) selecting at least one granular starch and at least one organic plasticizer for this starch, (b) preparing a plasticized composition by thermomechanically mixing this starch and this plasticizer, (c) optionally incorporating at least one functional substance carrying functions comprising an active hydrogen, (d) incorporating at least one bonding agent carrying at least two functional groups capable of reacting with molecules carrying functions comprising an active hydrogen, and optionally (e) heating the mixture to a temperature sufficient to cause the bonding agent to react with the plasticizer and with the starch and/or the functional substance, it being possible for steps (d) and (e) to be carried out simultaneously, and also a starch-based thermoplastic composition that can be obtained by means of this method.

Description

PROCESS FOR THE PREPARATION OF THERMOPLASTIC COMPOSITIONS BASED ON PLASTICIZED STARCH AND COMPOSITIONS THUS OBTAINED

The present invention relates to a new process for the preparation of starch-based thermoplastic compositions and the compositions thus obtained.

The term "thermoplastic composition" in the present invention means a composition which reversibly softens under the action of heat and hardens on cooling. It has at least one so-called glass transition temperature (Tg) below which the amorphous fraction of the composition is in the brittle glassy state, and above which the composition can undergo reversible plastic deformations. The glass transition temperature or at least one of the glass transition temperatures of the starch-based thermoplastic composition of the present invention is preferably from -50 to 150 ^° C. This starch-based composition can, of course, be shaped by the processes traditionally used in plastics (extrusion, injection, molding, blowing, calendering, etc.). Its viscosity, measured at a temperature of 100 ⁰ C to 200 ⁰ C, is generally between 10 and 10 ⁶ Pa. S.

Preferably, said composition is "hot melt", that is to say that it can be shaped without applying significant shear forces, that is to say by simple flow or by simply pressing the melt. Its viscosity, measured at a temperature of 100 ⁰ C to 200 ⁰ C, is generally between 10 and 10 ³ Pa. S.

In the current context of climate disturbances due to the greenhouse effect and global warming, the upward trend in fossil fuels, in particular the oil from which plastics are derived, the state of public opinion seeking sustainable development, more natural, cleaner, healthier and less energy-intensive products, and the evolution of regulations and taxation, it is necessary to have new compositions from renewable resources, which are particularly suitable for the field of plastic materials, and which are both competitive, designed from the outset to have only little or no negative impact on the environment, and technically as efficient as polymers prepared from raw materials of fossil origin.

Starch is a raw material with the advantages of being renewable, biodegradable and available in large quantities at an economically attractive price compared to the oil and gas used as raw materials for today's plastics.

The biodegradable nature of starch has already been exploited in the manufacture of plastics, according to two main technical solutions.

The first starch-based compositions developed were about thirty years ago. The starches were then used in the form of mixtures with synthetic polymers such as polyethylene, as filler, in the native granular state. Before dispersion in the synthetic polymer constituting the matrix, or continuous phase, the native starch is then preferably dried to a moisture content of less than 1% by weight, to reduce its hydrophilicity. For the same purpose, it can also be coated with fatty substances (fatty acids, silicones, siliconates) or to be modified on the surface of the grains by siloxanes or isocyanates.

The materials thus obtained generally contained approximately 10%, at most 20% by weight of granular starch, because beyond this value, the mechanical properties of the composite materials obtained became too imperfect and lowered compared with those of the synthetic polymers forming the matrix. In addition, it has been found that such polyethylene-based compositions are only biodegradable and non-biodegradable as expected, so that the expected growth of these compositions has not occurred. To overcome the lack of biodegradability, developments have also been carried out subsequently on the same principle but replacing only conventional polyethylene with oxidatively degradable polyethylenes or biodegradable polyesters such as polyhydroxybutyrate-co-hydroxyvalerate (PHBV) or poly (lactic acid) (PLA). Again, the mechanical properties of such composites obtained by mixing with granular starch have been found to be insufficient. Reference may be made to the excellent book "Green Chemistry", Paul Colonna, TEC & DOC Edition, January 2006, Chapter 6 entitled "Materials based on starches and their derivatives" by Denis Lourdin and Paul Colonna, pages 161 to 166.

Subsequently, the starch was used in a substantially amorphous and thermoplastic state. This state is obtained by plastification of the starch using a suitable plasticizer incorporated into the starch at a level generally between 15 and 25% relative to the granular starch, by supply of energy at a time. mechanical and thermal. U.S. Patent 5,095,054 to Warner Lambert and EP 0 497 706 B1 to Applicants describe in particular this destructured state, with reduced or absent crystallinity, and means for obtaining such thermoplastic starches.

However, the mechanical properties of thermoplastic starches, although they may be to some extent modulated by the choice of starch, plasticizer and the rate of use of the latter, are generally rather poor because the materials and obtained are still very highly viscous at high temperature (120 ⁰ C to 170 ⁰ C) and very brittle, too brittle, and very hard at low temperature, that is to say below the glass transition temperature or the temperature. highest glass transition temperature.

Thus, the elongation at break of such thermoplastic starches is very low, still less than about 10%, and this even with a very high plasticizer content of the order of 30%. By way of comparison, the elongation at break of low density polyethylenes is generally between 100 and 1000%.

In addition, the maximum breaking stress of thermoplastic starches decreases dramatically as the level of plasticizer increases. It has an acceptable value, of the order of 15 to 60 MPa, for a plasticizer content of 10 to 25%, but decreases unacceptably beyond 30%.

As a result, these thermoplastic starches have been the subject of numerous studies aimed at developing biodegradable and / or water-soluble formulations having better mechanical properties by physical mixing of these thermoplastic starches, or with polymers of petroleum origin such as polyvinyl acetate (PVA), polyvinyl alcohol (PVOH), ethylene / vinyl alcohol copolymers (EVOH), biodegradable polyesters such as polycaprolactones (PCL), poly (butylene adipate terephthalate) (PBAT) and poly (butylene succinate adipate) (PBS), or with polyesters of renewable origin such as poly (lactic acid) (PLA) ) or microbial polyhydroxyalkanoates (PHA, PHB and PHBV), or with natural polymers extracted from plants or animal tissues. We can refer again to the book "Green Chemistry", Paul Colonna, TEC & DOC Edition, pages 161 to 166, but also for example to patents EP 0 579 546 B1, EP 0 735 104 B1 and FR 2 697 259 of the Applicant which describe compositions containing thermoplastic starches.

Under the microscope, these resins appear to be very heterogeneous and present islands of plasticized starch in a continuous phase of synthetic polymers. This is because thermoplastic starches are very hydrophilic and are therefore very incompatible with synthetic polymers. It follows that the mechanical properties of such mixtures, even with the addition of compatibilizing agents such as, for example, copolymers comprising hydrophobic units and alternating hydrophilic units such as ethylene / acrylic acid (EAA) copolymers, or even cyclodextrins. or organosilanes, remain quite limited.

By way of example, the commercial product MATER-BI grade Y has, according to the information given by its manufacturer, an elongation at break of 27% and a maximum breaking stress of 26 MPa. As a result, these composite materials today find limited use, that is to say, limited essentially to the sectors of the overpack, trash bags, crate bags and some rigid, biodegradable mass objects.

The destructuring of the native semicrystalline granular state of the starch to obtain thermoplastic amorphous starches can be carried out in a medium that is poorly hydrated by the extrusion processes. Obtaining a melted phase from the starch granules requires not only a large supply of mechanical energy and thermal energy but also the presence of a plasticizer at the risk, otherwise, to carbonize the starch. Water is the most natural plasticizer of starch and is therefore commonly used, but other molecules are also very effective, including sugars such as glucose, maltose, fructose or sucrose; polyols such as ethylene glycol, propylene glycol, polyethylene glycols (PEG), glycerol, sorbitol, xylitol, maltitol or hydrogenated glucose syrups; urea, salts of organic acids such as sodium lactate and mixtures of these products.

The amount of energy to be applied to plasticize the starch can be advantageously reduced by increasing the amount of plasticizer. In practice, however, the use of a plasticizing agent at a high level relative to the starch induces various technical problems among which may be mentioned the following: a release of the plasticizer of the plasticized matrix at the end of manufacture or over time during storage, so that it is impossible to retain a quantity of plasticizer as high as desired and therefore obtain a sufficiently flexible and film-forming material, o high instability of the mechanical properties of the plasticized starch that hardens or softens depending on the humidity of the air, respectively when its water content decreases or increases, o the whitening or opacification of the surface of the composition by crystallization of the plasticizer used at high dose, as for example in the case of xylitol o a tacky or oily nature of the surface, as in the case of glycerol for example, o a very poor resistance to water, all the more problematic that the plasticizer content is high. A loss of physical integrity is noted in the water, so that the plasticized starch can not be cooled, at the end of manufacture, by immersion in a water bath such as traditional polymers. As a result, its uses are very limited. To extend its possibilities of use, it is necessary to mix it with large quantities, generally greater than or equal to 60%, of polyesters or other expensive polymers, and o a possible premature hydrolysis of the polyesters (PLA, PBAT, PCL , PET) optionally associated with thermoplastic starch.

The present invention provides an effective solution to the problems stated above.

The present invention relates to a process for preparing a thermoplastic composition based on starch comprising the following steps:

(a) selecting at least one granular starch (component 1) and at least one organic plasticizer (component 2) of this starch,

(b) preparing a plasticized composition by thermomechanical mixing of this starch and this organic plasticizer, (c) optionally incorporating into the plasticized composition obtained in step (b), at least one functional substance (optional component 4), other than granular starch and carrying active hydrogen functions and / or hydrolysis functions of such active hydrogen functions, and

(d) incorporating, in the plasticized composition obtained, at least one binding agent (component 3) bearing at least two functional groups capable of reacting with molecules carrying active hydrogen functions and capable of allowing fixation, by covalent bonds, at least a portion of the plasticizer on the starch and / or on the functional substance optionally added in step (c), said binding agent having a molar mass of less than 5000, and being chosen from diacids and compounds bearing at least two functions, free or masked, identical or different, chosen from the functions isocyanate, carbamoyl-caprolactam, epoxide, halogeno, acid anhydride, acyl halide, oxychloride, trimetaphosphate and alkoxysilane.

For the purposes of the invention, the term "granular starch" means a starch that is native or physically modified, chemically or enzymatically, having retained, within the starch granules, a semicrystalline structure similar to that evidenced in FIG. starch grains naturally present in reserve organs and tissues of higher plants, particularly in cereal grains, legume seeds, potato or cassava tubers, roots, bulbs, stems and the fruits. This semi-crystalline state is essentially due to macromolecules of amylopectin, one of the two main constituents of starch. In the native state, the grains of starch have a degree of crystallinity which varies from 15 to 45%, and which depends essentially on the botanical origin of the starch and the possible treatment it has undergone. Granular starch, placed under polarized light, has a characteristic black cross, so-called Maltese cross, typical of the granular state. For a more detailed description of granular starch, see Chapter II entitled "Structure and morphology of the starch grain" of S. Perez, in the book "Initiation to macromolecular chemistry and physico-chemistry". "First Edition 2000, Volume 13, pages 41 to 86, French Group for Studies and Applications of Polymers.

By "starch plasticizer" is meant any organic molecule of low molecular weight, i.e. preferably having a molecular weight of less than 5000, in particular less than 1000, which, when incorporated in the starch by thermomechanical treatment at a temperature of between 20 and 200 ^° C. results in a decrease in the glass transition temperature and / or a reduction in the crystallinity of a granular starch to a value of less than 15% or even an essentially amorphous state. This definition of the plasticizer does not include water, which, although having a starch plasticizing effect, has the major disadvantage of inactivating most of the functions likely to be present on the surface. crosslinking agent, such as epoxide or isocyanate functions.

"Functional substance" is understood to mean any molecule, other than granular starch, the binding agent and the plasticizer, carrying active hydrogen functions, that is to say functions having at least one hydrogen atom likely to be displaced if a chemical reaction takes place between the atom carrying this hydrogen atom and another reactive function. Active hydrogen functions are, for example, hydroxyl, protonic acid, urea, urethane, amide, amine or thiol functions. This definition also encompasses in the present invention any molecule, other than granular starch, the binding agent and the plasticizer, carrying functions capable of giving, in particular by hydrolysis, such active hydrogen functions. The functions which can give such functions to active hydrogen are, for example, the alkoxy functions, in particular the alkoxysilanes, or the acyl chloride, acid anhydride, epoxide or ester functions.

The functional substance is preferably an oligomer or organic polymer having a weight average molecular weight of between 5,000 and 5,000,000, in particular between 8500 and 3,000,000, in particular between 15,000 and 1,000,000 daltons.

The term "binding agent" means any molecule carrying at least two functional groups, free or masked, capable of reacting with molecules carrying active hydrogen functions, such as in particular the plasticizer of starch. This binding agent therefore allows the attachment, by covalent bonds, of at least a portion of the plasticizer on the starch and / or on the functional substance. This binding agent is distinguished from adhesion agents, physical compatibilizers or grafting agents in that they either create weak bonds (non-covalent) or carry only a single reactive function .

The molecular weight of the binding agent is preferably less than 5000 and most preferably less than 1000. Indeed, the low molecular weight of the binding agent allows its quick and easy incorporation into the plasticized starch composition by the plasticizer.

Preferably, said binding agent has a molecular weight of between 50 and 500, in particular between 90 and 300.

Preferably, the process comprises step (c) of incorporating at least one functional substance into the thermoplastic composition containing the starch and the plasticizer. In this case, that is to say when a functional substance is introduced, the binding agent used is preferably chosen so that one of its reactive functional groups is capable of reacting with the reactive functions of this functional group. functional substance. This makes it possible to at least partially fix the plasticizer by covalent bonding to the functional substance. The plasticizer can therefore be fixed at least in part, either on the starch or on the functional substance or on these two components at the same time.

The process of the present invention preferably further comprises a step (e) of heating the mixture obtained in step (d) to a temperature sufficient to react the binding agent with, on the one hand, the plasticizer and, secondly, with the starch and / or the functional substance possibly present. Steps (d) and (e) can be implemented simultaneously or one after the other after a very variable time.

The incorporation of the binding agent into the thermoplastic composition and the reaction with the starch and / or the functional substance (steps (c) and (d)) is preferably carried out by hot kneading at a temperature of between 60.degree. and 200 ^° C., and better still between 100 and 160 ^° C. The binding agent may be chosen for example from compounds carrying at least two functions, free or masked, identical or different, chosen from isocyanate, carbamoylcaprolactam, epoxide, halogeno, acid anhydride, acyl halide functions. , oxychloride, trimetaphosphate and alkoxysilane.

The binding agent may also be an organic diacid.

It may advantageously be the following compounds:

diisocyanates and polyisocyanates, preferably 4,4'-dicyclohexylmethane diisocyanate (H12MDI), methylenediphenyl diisocyanate (MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate; (HMDI) and lysine diisocyanate (LDI), dicarbamoylcaprolactams, preferably 1,1 'carbonyl-biscaprolactam,

diepoxides, halohydrins, that is to say compounds having an epoxide function and a halogen function, preferably epichlorohydrin, organic diacids, preferably succinic acid, adipic acid, acid glutaric acid, oxalic acid, malonic acid, maleic acid and the corresponding anhydrides, oxychlorides, preferably phosphorus oxychloride,

trimetaphosphates, preferably sodium trimetaphoshate,

alkoxysilanes, preferably tetraethoxysilane,

and any mixtures of these compounds.

In a preferred embodiment of the method of the invention, the binding agent is chosen from the diepoxides, diisocyanates and halohydrins. It is particularly preferred to use a linking agent selected from diisocyanates, methylenediphenyl diisocyanate (MDI) and 4,4'-dicyclohexylmethane diisocyanate (H12MDI) being particularly preferred.

The appropriate amount of binding agent depends in particular on the plasticizer content. Surprisingly and surprisingly, the higher the amount of plasticizer introduced, the greater the amount of binding agent can be increased without the end material becoming hard and losing its thermoplastic properties.

The amount of binding agent used is preferably between 0.01 and 15 parts, in particular between 0.1 and 12 parts and better still between 0.1 and 9 parts per 100 parts of plasticized composition of the step ( b), optionally containing the functional substance.

By way of example, this amount of binding agent can be between 0.5 and 5 parts, especially between 0.5 and 3 parts, per 100 parts by weight of plasticized composition of step (b), containing possibly the functional substance.

Unexpectedly, very small amounts of binding agent considerably reduce the sensitivity to water and water vapor of the final thermoplastic composition obtained according to the invention and thus allow it to be rapidly cooled in this way. end of manufacture by immersion in water, which is not the case for a plasticized starch prepared by simple mixing with the plasticizer, that is to say without the use of a binding agent capable of bind the plasticizer to the starch or possibly the functional substance introduced. It has also been found that the starch-based thermoplastic compositions prepared according to the claimed method have less thermal degradation and less coloration than the plasticized starches of the prior art. The latter, because of their high sensitivity to water, must also be necessarily cooled in the air, which requires much more time than cooling water. Moreover, this characteristic of water stability opens many new potential uses to the composition according to the invention.

The article entitled "Effect of Compatibilizer on the Blends of Starch / Biodegradable Polyesters" by Long Yu et al., Journal of Applied Polymer Science, Vol.103, 812-818 (2007), 2006, Wiley Periodicals Inc, describes effect of methylenediphenyl diisocyanate (MDI) as a compatibilizing agent for mixtures of a gelatinized starch with water (70% starch, 30% water) and a biodegradable polyester (PCL or PBSA), which are known to be not miscible with each other from a thermodynamic point of view. This document does not envisage at any time the use of an organic plasticizer, likely to replace the water which has the drawbacks, observed by the Applicant, to disable the isocyanate functions of the MDI used and not to obtain of a thermoplastic starchy composition of sufficient flexibility, probably due to the evaporation of the water at the outlet of the thermomechanical treatment device or during storage.

The article entitled, "Effects of Starch Moisture on Properties on Wheat Starch / Blight Containing Methylenediphenyl Diisocyanate" by Wang et al., Published in Journal of Polymers and the Environment, Flight. 10, No. 4, October 2002, also relates to the compatibilization of a starch phase and a poly (lactic acid) phase (PLA) by the addition of methylene diphenyl isocyanate (MDI). As in the previous article, water is the only plasticizer envisaged but has the drawbacks indicated above.

The article "Thermal and Mechanical Properties of Poly (lactic acid) / Starch / Methylenediphenyl Diisocyanate Blending with Triethyl Citrate" by Ke et al., Journal of Applied Polymer Science, Vol. 88, 2947-2955 (2003), concerns, like the two articles above, the problem of the thermodynamic incompatibility of starch and PLA. This paper investigates the effect of using triethyl citrate as a plasticizer in starch / PLA / MDI blends. However, it is clear from this document (see page 2952, left column, Morphology) that triethylcitrate acts as a plasticizing agent only for the PLA phase but not for the amylaceous phase which remains in the form of pelletized granules. starch dispersed in a PLA matrix plasticized with triethyl citrate.

International application WO 01/48078 describes a process for preparing thermoplastic materials by incorporating a synthetic polymer in the molten state in thermoplastic compositions. This document envisages, certainly, the use of a polyol type plasticizer, but does not mention at any time the possibility of fixing the plasticizer on the starch and / or the synthetic polymer via a difunctional bonding agent of the polyol type. low molecular weight.

The article entitled "The influence of citric acid on the properties of thermoplastic starch / linear low-density polyethylene blends" by Ning et al. Carbohydrate Polymers, 67, (2007), 446-453, investigates the effect of the presence of citric acid on thermoplastic starch / polyethylene blends. This document does not envisage at any time the fixing of the plasticizer used (glycerol) on the starch via a bi- or polyfunctional compound. The spectroscopy results show no covalent bond between citric acid and starch or polyethylene. It is simply observed that the physical bonds (hydrogen bonds) between starch and glycerol are reinforced by the presence of citric acid.

In conclusion, none of the above documents describes or suggests a method similar to that of the present invention comprising incorporating a reactive, at least bifunctional, binding agent as claimed in a plasticized dye-based composition. starch and a plasticizer of the starch, and binding of the plasticizer to the starch and / or a functional substance via the bifunctional linker as claimed.

According to the invention, the granular starch can come from any botanical origin. It may be starch native to cereals such as wheat, maize, barley, triticale, sorghum or rice, tubers such as potato or cassava, or legumes such as peas and soybeans, and mixtures of such starches. According to a preferred variant, the granular starch is an acid hydrolyzed starch, oxidizing or enzymatic, or an oxidized starch. It can be a starch commonly called fluidized starch or a white dextrin. It may also be a starch modified physico-chemically but having essentially retained the structure of the native starch starting, such as starches esterified and / or etherified, in particular modified by acetylation, hydroxypropylation, cationization, crosslinking, phosphatation, or succinylation, or starches treated in aqueous medium at low temperature ("annealing"), treatment which is known to increase the crystallinity of starch. Preferably, the granular starch is a native, hydrolyzed, oxidized or modified starch of wheat or pea.

The granular starch generally has a degree of solubles at 20 ^° C. in demineralized water, less than 5% by weight. It is preferably almost insoluble in cold water.

The plasticizer of the starch is preferably chosen from diols, triols and polyols such as glycerol, polyglycerol, isosorbide, sorbitans, sorbitol, mannitol, and hydrogenated glucose syrups. organic acids such as sodium lactate, urea and mixtures of these products. The plasticizer advantageously has a molar mass of less than 5000, preferably less than 1000, and in particular less than 400. The organic plasticizer naturally has a molar mass greater than 18, ie it does not encompass the water.

Due to the presence of the binding agent, the amount of plasticizer used in the present invention may advantageously be relatively high relative to the amount of plasticizer used in the plasticized starches of the prior art. The plasticizer is incorporated into the granular starch preferably in the proportion of 10 to 150 parts by weight, preferably in the proportion of 25 to 120 parts by weight and in particular in the proportion of 40 to 120 parts by weight per 100 parts by weight. starch weight. The functional substance carrying active hydrogen functional groups and / or functions which, in particular by hydrolysis of such active hydrogen functions, may be a polymer of natural origin, or a synthetic polymer obtained from monomers of fossil origin and / or monomers from renewable natural resources.

Polymers of natural origin can be obtained by extraction from plants or animal tissues. They are preferably modified or functionalized, and are in particular of the protein type, cellulosic, lignocellulosic, chitosan and natural rubbers.

It is also possible to use polymers obtained by extraction from micro-organism cells, such as polyhydroxyalkanoates (PHAs).

Such a polymer of natural origin may be chosen from flours, modified or unmodified proteins, unmodified or modified celluloses, for example by carboxymethylation, ethoxylation, hydroxypropylation, cationization, acetylation, alkylation, hemicelluloses, lignins, guars. modified or unmodified chitins and chitosans, gums and natural resins such as natural rubbers, rosins, shellacs and terpene resins, polysaccharides extracted from algae such as alginates and carrageenans, polysaccharides bacterial origin such as xanthans or PHAs, lignocellulosic fibers such as flax fibers.

The synthetic polymer obtained from monomers of fossil origin, preferably comprising active hydrogen functions may be chosen from synthetic polymers of polyester, polyacrylic type, polyacetal, polycarbonate, polyamide, polyimide, polyurethane, polyolefin, functionalized polyolefin, styrenic, functionalized styrene, vinyl, functionalized vinylic, functionalized fluorinated, functionalized polysulfone, functionalized polyphenyl ether, functionalized polyphenylsulfide, functionalized silicone and functionalized polyether.

By way of example, mention may be made of PLA, PBS, PBSA, PBAT, PET, polyamides (PA) 6, 6-6, 6-10, 6-12, 11 and 12, copolyamides, polyacrylates, polyvinyl alcohol, polyvinyl acetate, ethylene-vinyl acetate copolymers (EVA), ethylene-methyl acrylate copolymers (EMA), ethylene-vinyl alcohol copolymers (EVOH) polyoxymethylenes (POM), acrylonitrile-styrene-acrylate copolymers (ASA), thermoplastic polyurethanes (TPU), polyethylenes or polypropylenes functionalized for example with silane, acrylic or maleic anhydride units and styrene-butylene-styrene copolymers ( SBS) and styrene-ethylene-butylene-styrenes (SEBS) preferably functionalized for example with maleic anhydride units and any mixtures of these polymers.

The polymer used as a functional substance may also be a polymer synthesized from monomers derived from natural resources which are renewable in the short term such as plants, microorganisms or gases, in particular from sugars, glycerin, oils or their derivatives such as alcohols or acids, mono-, di- or polyfunctional, and in particular from molecules such as bio-ethanol, bio-ethylene glycol, bio-propanediol, 1,3-propanediol biosourced, bio-butane-diol, lactic acid, succinic acid biosourced, glycerol, isosorbide, sorbitol, sucrose, diols derived from vegetable or animal oils and resin acids extracted from pine.

It may be in particular polyethylene obtained from bioethanol, polypropylene derived from bio-propanediol, polyesters of PLA or PBS type based on lactic acid or succinic acid biosourced, polyesters of PBAT type based on butane- diol or biosourced succinic acid, SORONA®-type polyesters based on 1,3-propanediol biosourced, polycarbonates containing isosorbide, polyethylene glycols based on bio-ethylene glycol, polyamides based on castor oil or plant polyols, and polyurethanes based for example on plant diols, glycerol, isosorbide, sorbitol or sucrose.

Preferably, the non-starchy polymer is chosen from ethylene-vinyl acetate copolymers (EVA), polyethylenes (PE) and polypropylenes (PP) which are not functionalized or functionalized, in particular by silane units, acrylic units or maleic anhydride units. thermoplastic polyurethanes (TPU), poly (butylene succinate) (PBS), poly (butylene succinate-co-adipate) (PBSA), poly (butylene adipate terephthalate) (PBAT), styrene-butylene-styrene copolymers and styrene-ethylene-butylene-styrene (SEBS), preferably functionalized, in particular by maleic anhydride units, amorphous poly (ethylene terephthalate) (PETG), synthetic polymers obtained from bio-sourced monomers, polymers extracted from plants, animal tissues and microorganisms, optionally functionalized, and mixtures thereof.

Examples of particularly preferred non-starch polymers are polyethylenes (PE) and polypropylenes (PP), preferably functionalized, styrene-ethylene-butylene-styrene copolymers (SEBS), preferably functionalized, amorphous poly (ethylene terephthalate) (PETG) and thermoplastic polyurethanes.

Advantageously, the non-starchy polymer has a weight average molecular weight of between 8500 and 10,000,000 daltons, in particular between 15,000 and 1,000,000 daltons.

Moreover, the non-starchy polymer preferably consists of carbon of renewable origin according to ASTM D6852 and is advantageously non-biodegradable or non-compostable in the sense of the standards EN 13432, ASTM D6400 and ASTM 6868.

In a preferred embodiment of the process of the invention, the plasticized composition of step (b), optionally containing a functional substance (optional component 4), is dried or dehydrated, before the incorporation of the binding agent. (component 3) in step (d), to a residual moisture content of less than 5%, preferably less than 1%, and in particular less than 0.1%.

Depending on the amount of water to be removed, this drying or dehydration step can be carried out batchwise or continuously during the process.

Preferably, the thermomechanical mixture of the native starch and the plasticizer is carried out by hot kneading at a temperature of preferably between 60 and 200 ^° C., more preferably between 100 and 160 ^° C., in a discontinuous manner, for example by kneading. mixing, or continuously, for example by extrusion. The duration of this mixture can be from a few seconds to a few hours, depending on the mixing mode selected. Similarly, the incorporation, during step (d), of the binding agent into the plasticized composition can be carried out by thermomechanical mixing, discontinuously or continuously and in particular online, by reactive extrusion. . In this case, the mixing time can be short, from a few seconds to a few minutes.

The present invention also relates to a thermoplastic composition based on starch obtainable by the method of the invention.

The composition in accordance with the invention is thermoplastic in the meaning defined above and therefore advantageously has a complex viscosity, measured on a PHYSICA MCR 501 or equivalent type rheometer, of between 10 and 10 ⁶ Pa.s, for a temperature of between 100 and 200 ^° C. For injection uses for example, its viscosity at these temperatures may be rather low and the composition is then preferentially heat-fusible in the sense specified above.

This composition is either a simple mixture of the three or four components (starch, plasticizer, binding agent, optional functional substance), or a mixture comprising macromolecular products resulting from the reaction of the binding agent with each of two or three other components. In other words, the subject of the present invention is not only the composition obtained at the end of step (e), but also that obtained at the end of step (d), that is to say before reaction. in step (e), the binding agent with the other components.

Of course, the advantageous properties of the thermoplastic compositions of the present invention those of the compositions resulting from step (e) having undergone the reaction step of the binding agent.

When the compositions of the present invention contain a functional substance, they preferably have a "solid dispersion" type structure. In other words, the compositions of the present invention contain the plasticized starch in the form of domains dispersed in a matrix of continuous functional substance. This dispersion-type structure must be distinguished in particular from a structure where the plasticized starch and the functional substance constitute only one and the same phase, or else compositions containing two co-continuous networks of plasticized starch and substance. functional. The object of the present invention is indeed not to prepare materials that are above all biodegradable, but plastics with a high starch content having excellent rheological and mechanical properties.

For the same reason, the functional substance is preferably chosen from non-biodegradable synthetic polymers in accordance with the standards EN 13432, ASTM D6400 and ASTM 6868.

The thermoplastic compositions according to the invention have the advantage of being sparingly soluble or even totally insoluble in water, of being difficult to hydrate and of maintaining good physical integrity after immersion in water. Their level of insolubles in water, at 20 ^° C., is preferably greater than 72%, in particular greater than 80%, more preferably greater than 90%. Very advantageously, it may be greater than 92%, especially greater than 95%. Ideally, this insoluble content may be at least 98% and in particular be close to 100%. Moreover, the degree of swelling of the thermoplastic compositions according to the invention, after immersion in water at 20 ^° C. for a period of 24 hours, is preferably less than 20%, in particular less than 12%, more preferably less than at 6%. Very advantageously, it may be less than 5%, especially less than 3%. Ideally, this swelling rate is at most equal to 2% and may especially be close to 0%.

Unlike compositions with high levels of thermoplastic starch of the prior art, the composition according to the invention advantageously has characteristic stress / strain curves of a ductile material, and not of a fragile type material. The elongation at break, measured for the compositions of the present invention, is greater than 40%, preferably greater than 80%, more preferably greater than 90%. This elongation at break can advantageously be at least 95%, especially at least equal to 120%. It can even reach or exceed 180% or even 250%. It is generally reasonably less than 500%.

The maximum breaking stress of the compositions of the present invention is generally greater than 4 MPa, preferably greater than 6 MPa, more preferably greater than 8 MPa. It can even reach or exceed 10 MPa, or even 20 MPa. It is generally reasonably less than 80 MPa.

In one embodiment, the thermoplastic composition of the present invention contains a functional substance as described above. This functional substance is preferably a polymer chosen from functionalized polyethylenes (PE) and polypropylenes (PP), styrene-ethylene copolymers Functionalized butylene-styrene (SEBS), amorphous poly (ethylene terephthalate) and thermoplastic polyurethanes (PTU).

The composition according to the invention may also comprise various other additional products. It may be products intended to improve its physico-chemical properties, in particular its implementation behavior and its durability or its mechanical, thermal, conductive, adhesive or organoleptic properties.

The additional product may be an improving or adjusting agent for the mechanical or thermal properties chosen from minerals, salts and organic substances, in particular from nucleating agents such as talc, compatibilizing agents such as surfactants, impact or scratch-resistant improvers such as calcium silicate, shrinkage control agents such as magnesium silicate, scavengers or deactivators of water, acids, catalysts, metals, oxygen , infra-red rays, UV rays, hydrophobing agents such as oils and greases, hygroscopic agents such as pentaerythritol, flame retardants and fireproofing agents such as halogenated derivatives, anti-smoke agents, reinforcing fillers, mineral or organic, such as clays, carbon black, talc, vegetable fibers, glass fibers or Kevlar.

The additional product may also be an improving agent or an adjustment of the conductive or insulating properties with respect to electricity or heat, for example sealing against air, water or gases. , solvents, fats, essences, aromas, perfumes, chosen among the minerals, salts and organic substances, in particular among nucleating agents such as talc, compatibilizers such as surfactants, scavengers or deactivators of water, acids, catalysts, metals, oxygen or infrared radiation, hydrophobing agents such as oils and fats, pearling agents, hygroscopic agents such as pentaerythritol, heat conduction or dissipation agents such as metal powders, graphites and salts, and micrometric reinforcement like clays and carbon black.

The additional product may be an agent that improves the organoleptic properties, in particular:

- odorant properties (perfumes or odor masking agents), optical properties (glossing agents, whitening agents such as titanium dioxide, dyes, pigments, dye enhancers, opacifiers, matting agents such as carbonate calcium, thermochromic agents, phosphorescence and fluorescence agents, metallizing or marbling agents and anti-fogging agents), sound properties (barium sulphate and barytes), and

- tactile properties (fat).

The additional product may also be an enhancing or adjusting agent for adhesive properties, including adhesion to cellulosic materials such as paper or wood, metal materials such as aluminum and steel, glass or ceramic materials, textiles and mineral materials, such as pine resins, rosin, ethylene / vinyl alcohol copolymers, fatty amines, lubricating agents, mold release agents, antistatic agents and anti-blocking agents.

Finally, the additional product may be an agent improving the durability of the material or an agent for controlling its (bio) degradability, especially chosen from hydrophobing agents such as oils and greases, anti-corrosion agents, antimicrobial agents such as Ag, Cu and Zn, degradation catalysts such as oxo-catalysts and enzymes such as amylases.

The thermoplastic composition of the present invention also has the advantage of being essentially renewable raw materials and can be presented, after adjustment of the formulation, the following properties, useful in multiple applications in plastics or other fields : suitable thermoplasticity, melt viscosity and glass transition temperature, in the usual known value ranges of the current polymers (Tg from -50 ° to 150 ^° C.), allowing implementation using existing industrial installations and used conventionally for the usual synthetic polymers,

- sufficient miscibility with a wide variety of polymers of fossil origin or of renewable origin on the market or in development,

- a satisfactory physicochemical stability under the conditions of implementation,

- low sensitivity to water and water vapor,

mechanical performance very significantly improved compared to thermoplastic starch compositions of the prior art (flexibility, elongation at break, maximum breaking stress) - good barrier effect to water, water vapor, oxygen, carbon dioxide, UV, fats, aromas, essences, fuels,

- opacity, translucency or transparency adjustable according to the uses,

good printability and ability to be painted, in particular with water-based inks and paints,

- controllable removal,

- stability over time sufficient biodegradability, compostability and / or recyclability adjustable.

In a very remarkable manner, the starch-based thermoplastic composition according to the invention can, in particular, present simultaneously:

an insoluble level of at least 98%,

a swelling rate of less than 5%,

an elongation at break of at least 95%, and

a maximum stress at break greater than 8 MPa.

The thermoplastic composition according to the invention can be used as such or in admixture with synthetic, artificial or naturally occurring polymers. It can be biodegradable or compostable according to EN 13432, ASTM D6400 and ASTM 6868, and then include polymers or materials that meet these standards, such as PLA, PCL, PBSA, PBAT and PHA.

It can in particular make it possible to correct certain major known defects of the PLA, namely

the poor barrier effect to CO ₂ and oxygen,

- the barrier effects to water and insufficient water vapor, insufficient heat resistance for the manufacture of bottles and resistance to heat very insufficient for use as textile fibers, and

- fragility and lack of flexibility in the state of films.

The composition according to the invention is however preferably non-biodegradable or non-compostable in the sense of the above standards, and then comprises, for example, known synthetic polymers or starches or extraction polymers highly functionalized, crosslinked or etherified. The best performances in terms of rheological properties, mechanical properties and insensitivity to water have indeed been obtained with such non-biodegradable and non-compostable compositions.

It is possible to modulate the lifetime and the stability of the composition according to the invention by adjusting in particular its affinity for water, so as to suit the expected uses as a material and the recovery methods envisaged in the end. of life .

The composition according to the invention advantageously contains at least 33%, preferably at least 50%, in particular at least 60%, more preferably at least 70%, or more than 80% of renewable carbon in the sense of the standard. ASTM D6852. This carbon of renewable origin is essentially that constitutive of the starch necessarily present in the composition according to the invention but can also be advantageously, by a judicious choice of the constituents of the composition, that present in the plasticizer of the starch as in the case for example glycerol or sorbitol, but also that present in the functional substance, any other functional product or any additional polymer when they come from renewable natural resources such as those defined preferentially above.

It is in particular conceivable to use the thermoplastic compositions based on starch according to the invention, as barrier films with water, with water vapor, with oxygen, with carbon dioxide, with aromas, to fuels for automotive fluids, organic solvents and / or fats, alone or in multi-layer or multi-ply structures obtained by coextrusion, lamination or other techniques, for the field of packaging of carriers printing, insulation, or textile in particular.

The compositions of the present invention may also be used to increase hydrophilicity, electrical conduction ability or microwaves, printability, dyeability, bulk coloring or paintability. anti-static or anti-dust effect, scratch resistance, fire resistance, adhesive power, heat sealability, sensory properties, in particular touch and acoustic properties, permeability to water and / or water vapor, or the resistance to organic solvents and / or fuels, of synthetic polymers in the context for example of the manufacture of membranes, films, printable electronic labels, textile fibers, containers or reservoirs, synthetic hot melt films, parts obtained by injection or extrusion such as automobile parts.

It should be noted that the relatively hydrophilic nature of the thermoplastic composition according to the invention considerably reduces the risks of accumulation in adipose tissue of living organisms and thus also in the food chain.

The composition according to the invention may be in pulverulent, granular or bead form and form the matrix of a dilutable masterbatch in a bio-sourced matrix or not.

The invention also relates to a plastic or elastomeric material comprising the thermoplastic composition of the present invention or a finished or semi-finished product obtained therefrom.

Example 1

Comparison of compositions based on wheat starch according to the invention with compositions according to the prior art prepared without a binding agent

For this example, use is made of: a native wheat starch marketed by the Applicant under the name "SP wheat starch" having a water content of about 12% (component 1),

a concentrated aqueous composition of polyols based on glycerol and sorbitol, marketed by the Applicant under the name POLYSORB G84 / 41/00 having a water content of about 16% (component 2) of methylene diphenyl diisocyanate ( MDI) marketed under the name Suprasec 1400 by the company Hunstman (component 3).

(a) Preparation of basic thermoplastic compositions (TPS): A thermoplastic composition according to the prior art is prepared. For this purpose, a TSA brand twin-screw extruder with a diameter (D) of 26 mm and a length of 56 D is fed with the starch and the plasticizer, so as to obtain a total material flow rate of 15 kg / h, varying the ratio of plasticizer mixture (POLYSORB) / wheat starch as follows:

-100 parts / 100 parts (Composition AP5050),

- 67 parts / 100 parts (composition AP6040),

- 54 parts / 100 parts (Composition AP6535),

- 43 parts / 100 parts (Composition AP7030).

The extrusion conditions are as follows:

- Temperature profile (ten heating zones Zl to ZlO): 90/90/110/140/140/110/90/90/90/90

- Screw speed: 200 rpm.

At the extruder outlet, it is found that the materials thus obtained are too sticky at high levels of plasticizer (compositions AP5050 and AP6040) to be granulated on a material commonly used with synthetic polymers. It is also noted that the compositions are still too sensitive to water to be cooled in a cold water tank. For these reasons, the plasticized starch rods are cooled in air on a conveyor belt and then dried at 80 ^° C. in a vacuum oven for 24 hours and then granulated.

(b) Preparation of compositions according to the invention (with MPI) and according to the prior art (without MPI)

Then, in the thermoplastic composition thus obtained in the form of granules, during a second passage in the extruder, 0, 1, 2, 4, 6, 8 and 12 parts of MPI per 100 parts of thermoplastic composition ( pcr). Due to an excessive increase in the viscosity, or even a crosslinking of the material in the extruder, and an irreversible loss of the thermoplastic character of the composition, it was impossible to incorporate:

- more than 8 pcr of MDI in the composition AP6040

more than 4 phr of MDI in the composition AP6535 and more than 2 phr of MDI in the composition AP7030.

Water stability test:

The water and moisture sensitivity of the compositions prepared and the ability of the plasticizer to migrate to water and thereby to induce degradation of the structure of the material are evaluated.

The level of insoluble in water of the compositions obtained is determined according to the following protocol:

(i) Dry the sample to be characterized (12 hours at 80 ^° C. under vacuum)

(ii) Measure the mass of the sample (= MsI) with a precision scale.

(iii) Immerse the sample in water at 20 ^° C. (volume of water in ml equal to 100 times the mass in g of sample).

(iv) Take the sample after a defined time of several hours.

(v) Remove excess surface water with absorbent paper as soon as possible.

(vi) Place the sample on a precision scale and follow the loss of mass for 2 minutes (measure the mass every 20 seconds)

(vii) Determine the mass of the swollen sample by graphing the previous measurements as a function of time and extrapolation to t = 0 of the mass

(= Mg).

(viii) Dry the sample (for 24 hours at 80 ^° C. under vacuum). Measure the mass of the dry sample (= Ms2)

(ix) Calculate the insoluble content, expressed in percent, according to the formula Ms2 / Msl.

(x) Calculate the swelling rate, in percent, according to the formula (Mg-MsI) / MsI.

Water recovery test:

The rate of moisture uptake is determined by measuring the mass of a plasticized starch sample after one month of storage, before drying (M _h ) and after drying under vacuum at 80 ^° C. for 24 hours (M _s ). The moisture recovery rate corresponds to the difference (1-M _s / M _h ) expressed in percent.

Table 1: Moisture uptake rate and water insoluble content of plasticized starches with or without MPI

*: According to the prior art **: According to the invention

Table 1 shows that the incorporation of MDI according to the invention results in both a clear decrease in the rate of moisture uptake, a very significant decrease in the solubilization kinetics and a significant increase in the level of insolubles in the water.

These results suggest that the plasticizer is bound to starch by MDI, used as a binding agent. The mass spectrometric analysis has furthermore shown that the thermoplastic compositions thus prepared in accordance with the invention, using a binding agent such as MDI, contain specific entities of glucose-MDI-glycerol and glucose type. -MDI-sorbitol, attesting the fixing of the plasticizer on the starch via the binding agent.

The compositions according to the invention prepared by reaction of a binding agent (MDI) with the starch-based thermoplastic compositions of the state of the art, are more stable to moisture and water than the compositions. of the prior art without MDI.

Example 2

Adding a functional substance

In order to further increase the water stability of the thermoplastic base starch mixture AP6040 obtained according to Example 1, MDI and a polyethylene grafted with 2% vinyltrimethoxysilane (PEgSi) are mixed with this composition, thus forming a dry blend. The PEgSi used was obtained beforehand by grafting vinyltrimethoxysilane on a low density PE by extrusion. An example of such a PEgSi available on the market is the product BorPEX ME 2510 or BorPEX HE2515 both marketed by Borealis.

The twin-screw extruder previously described is fed by this dry blend.

The extrusion conditions are as follows:

Temperature profile (ten heating zones Z1 to Z10): 150 ^° C.

- Screw speed: 400 rpm.

The following compositions are prepared by introducing different levels of MDI: 0; 2 and 4 parts per 100 parts of thermoplastic composition AP6040 (phr).

The compositions prepared are shown in the table below.

Table 2

Compositions of Silane / AP6040 grafted PE alloys and results of resistance to water obtained

* 0 = impossible, I = possible but sticky surface, 2 = possible without problem (hydrophobic)

** After 24 (72) hours in water at 20 ^° C

Measurement of mechanical properties:

The mechanical tensile characteristics of the various samples are determined according to standard NF T51-034 (Determination of tensile properties) using a Lloyd Instrument LR5K test bench, a tensile speed of 50 mm / min and standard test specimens. H2.

From the tensile curves (stress = f (elongation), obtained at a stretching speed of 50 mm / min, for each silane-bonded PE / AP6040 alloy, the elongation at break and the maximum stress are recorded. at the corresponding break. Table 3

The 07641 mixture containing 30% silane-grafted PE, produced without MDI, is very hydrophilic and therefore can not be cooled in the water leaving the die because it dislocates very quickly by hydration in the cooling bath.

All plasticized starch / PEgSi alloys prepared with a binding agent (MDI), even those containing less than 30% PEgSi are very little hydrophilic and can advantageously be readily cooled in water.

Above 30%, the alloys made with MDI are very hydrophobic.

The mechanical properties of the compositions prepared with MDI are also good to very good in terms of elongation and tensile strength.

The MDI, by binding the plasticizer to the macromolecules of starch and PEgSi, greatly improves the properties of water resistance and mechanical strength, thus opening the compositions according to the invention, multiple new uses possible compared to those of the prior art.

In addition, optical and scanning electron microscopy observations show that the compositions thus prepared according to the invention are in the form of starch dispersions in a continuous polymer matrix of PegSi.

All these alloys have in particular a good scratch resistance and a "leather" feel. They can thus find for example an application as a coating of fabrics, wood panels, paper or cardboard.

Claims

A process for preparing a thermoplastic starch composition comprising the steps of:

(a) selecting at least one granular starch (component 1) and at least one organic plasticizer (component 2) of this starch,

(b) preparing a plasticized composition by thermomechanical mixing of this starch and this organic plasticizer,

(c) optionally incorporating into the plasticized composition obtained in step (b), at least one functional substance (optional component 4), other than granular starch and carrying active hydrogen functions and / or hydrolysis functions of such active hydrogen functions, and

(d) incorporation, into the plasticized composition obtained, of at least one binding agent (component 3) having a molar mass of less than 5000, chosen from organic diacids and compounds bearing at least two functions, free or masked , identical or different, chosen from isocyanate, carbamoyl-caprolactam, epoxide, halogeno, acid anhydride, acyl halide, oxychloride, trimetaphosphate and alkoxysilane functions.

2. Method according to claim 1, characterized in that it further comprises a step

(e) heating the mixture obtained in step (d) to a temperature sufficient to react the binding agent with, on the one hand, the plasticizer and, on the other hand, with the starch and or the functional substance possibly present, the steps (d) and (e) being able to be simultaneous.

3. Method according to claim 1 or 2, characterized in that it comprises the step (c) of introducing at least one functional substance

(component 4).

4. Method according to any one of the preceding claims, characterized in that the plasticizer (component 2) is chosen from diols, triols, polyols, organic acid salts, urea and mixtures of these products.

5. Method according to claim 4, characterized in that the plasticizer is chosen from glycerol, polyglycerols, isosorbide, sorbitans, sorbitol, mannitol, hydrogenated glucose syrups, sodium lactate, and mixtures of these products.

6. Process according to any one of the preceding claims, characterized in that the plasticizer is incorporated in the granular starch in a proportion of 10 to 150 parts by weight, preferably in a proportion of 25 to 120 parts by weight, and in particular at a rate of 40 to 120 parts by weight per 100 parts by weight of starch.

7. Method according to any one of the preceding claims, characterized in that the binding agent is chosen from the following compounds:

diisocyanates and polyisocyanates, preferably 4,4'-dicyclohexylmethane diisocyanate (H12MDI), methylenediphenyl diisocyanate (MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI) and hexamethylene diisocyanate; (HMDI) and lysine diisocyanate (LDI), dicarbamoylcaprolactams, preferably 1,1'-carbonyl-biscaprolactam,

diepoxides,

halohydrins, preferably epichlorohydrin, organic diacids, preferably succinic acid, adipic acid, glutaric acid, oxalic acid, malonic acid, maleic acid and the corresponding anhydrides, oxychlorides, preferably phosphorus oxychloride; , trimetaphosphates, preferably sodium trimetaphosphate,

alkoxysilanes, preferably tetraethoxysilane, and mixtures of these compounds.

8. Process according to Claim 7, characterized in that the binding agent is chosen from diisocyanates, diepoxides and halohydrins.

9. Process according to Claim 8, characterized in that the binding agent is a diisocyanate, preferably methylenediphenyl diisocyanate (MDI) or 4,4'-dicyclohexylmethane diisocyanate (H12MDI).

10. Process according to any one of the preceding claims, characterized in that the amount of binding agent used is between 0.01 and 15 parts, preferably between 0.1 and 12 parts and better still between 0.1. and 9 parts per 100 parts of plasticized composition of step (b), optionally additionally containing a functional substance

(component 4).

11. Method according to any one of the preceding claims, characterized in that the granular starch (component 1) is a native starch of cereals, tubers or legumes, an acid hydrolyzed, oxidizing or enzymatic starch, a starch oxidized, white dextrin, esterified starch and / or etherified, or a starch having undergone treatment in aqueous medium at low temperature (annealing).

12. Method according to any one of the preceding claims, characterized in that the plasticized composition, optionally containing a functional substance (component 4), is dried or dehydrated, before the incorporation of the binding agent, until a residual moisture content less than 5%, preferably less than 1%, in particular less than 0.1%.

13. Starch-based thermoplastic composition obtainable by a process according to any one of claims 1 and 3 to 12.

14. Thermoplastic composition based on starch obtainable by a process according to any one of claims 2 to 12, characterized in that it has a level of insoluble in water at 20 ⁰ C, greater than 72%, preferably greater than 80%, in particular greater than 90%.

15. Composition according to claim 14, characterized in that it has, after immersion in water at 20 ⁰ C for 24 hours, a swelling rate of less than 20%, preferably less than 12%, better still less than 6%.

16. Composition according to claim 14 or 15, characterized in that it has an elongation at break greater than 40%, preferably greater than 80% and in particular greater than 90%.

17. Composition according to any one of claims 14 to 16, characterized in that it has a maximum tensile strength greater than 4 MPa, preferably greater than 6 MPa and in particular greater than 8 MPa.

18. Composition according to any one of claims 14 to 17, characterized in that it has:

an insoluble level of at least 98%,

a swelling rate of less than 5%,

an elongation at break of at least 95%, and

a maximum stress at break greater than 8 MPa.

19. Composition according to any one of claims 13 to 18, characterized in that it is non-biodegradable or non-compostable in the sense of standards EN 13432, ASTM D6400 and ASTM 6868.

20. Composition according to any one of claims 13 to 19, characterized in that it contains at least 33%, preferably at least 50% of carbon of renewable origin within the meaning of ASTM D6852.

21. Composition according to any one of claims 13 to 20, characterized in that it contains, as functional substance, a polymer selected from functionalized polyethylenes (PE) and polypropylenes (PP), styrene-ethylene copolymers. Functionalized butyl-styrene (SEBS), amorphous poly (ethylene terephthalate) and thermoplastic polyurethanes (PTU).