WO2011086292A1

WO2011086292A1 - Compositions containing plant matter and synthetic fibres and method for preparing such compositions

Info

Publication number: WO2011086292A1
Application number: PCT/FR2010/052870
Authority: WO
Inventors: Léon Mentink; Didier Beaudoux; Bernard Constant
Original assignee: Roquette Freres
Priority date: 2009-12-22
Filing date: 2010-12-22
Publication date: 2011-07-21
Also published as: FR2954331A1; FR2954331B1; CN102753611A; EP2516535A1

Abstract

The present invention relates to a composition containing plant matter and synthetic fibres, characterised in that said composition includes: at least 10 wt% and at most 95 wt% of a thermoplastic composition (a) including at least one polyolefin and at least one thermoplastic starch; and at least 5 wt% and at most 90 wt% of synthetic fibres (b) having a diameter of 2 to 35 microns and a specific modulus of 25 to 230 GPa.m³/kg.

Description

COMPOSITIONS BASED ON PLANT MATERIAL AND SYNTHETIC FIBERS AND PROCESS FOR PREPARING SUCH

Compositions. The present invention relates to novel compositions comprising a thermoplastic composition based on polyolefin and plasticized starch (a) and synthetic fibers (b). It also relates to a process for preparing these compositions.

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 -120 ° C to 150 ° C. This thermoplastic composition has an ability to be shaped by the processes traditionally used in the plastic, textile or wood processing industries, such as extrusion, injection, molding, rotational molding, thermoforming, blowing, spinning, calendering or pressing. Its viscosity, measured at a temperature of 100 ° C. to 200 ° C., is generally between 10 and 10 ⁶ Pa.s.

Preferably, said thermoplastic composition is "heat fusible", that is to say that it can be shaped without application of significant shear forces, that is to say by simple flow or by simple pressing melted matter. Its viscosity, measured at a temperature of 100 ° C. to 200 ° C., is generally between 10 and 10 ³ Pa.s.

For the purposes of the present invention, the term "synthetic fibers" is intended to mean a composition obtained by shaping, in particular after melting or pyrolysis, a material of mineral, fossil or organic origin, fibers of diameter from 2 to 35 microns and of variable length. These synthetic fibers preferably have a high specific modulus, between 25 and 230 GPa.mVkg and are in particular of siliceous nature (glass fibers), of a carbon-like nature (carbon fibers), of a metallic nature (steel fibers or aluminum) or synthetic polymeric nature (PET fibers, PBT, PS, PP, PA, PLA, PU, aramids). It can therefore be both inorganic fibers and organic fibers. This definition excludes in fact vegetable fibers, that is to say fibers as present in nature, especially in plants.

In the current environmental and economic context, the depletion of oil and gas reserves from which traditional plastics, also known as petro-plastics as opposed to bioplastics based on renewable resources, derive from climate disturbances due to the greenhouse effect and global warming. the state of public opinion in search of sustainable development and more natural, cleaner, healthier, recyclable and less energy-intensive products, and the evolution of regulations and taxation, it is necessary to have new compositions from renewable resources that are both competitive, designed from the outset to have little or no negative impact on the environment and technically as efficient as materials prepared from materials first traditional and fossil origin.

In this spirit, different routes have been explored for several decades already, consisting in introducing bio-sourced materials as reinforcements in petro-plastic resins and especially in polyolefins. The latter have the advantages of being produced in very large volumes at relatively low prices, of presenting eco-profiles which are quite interesting with regard to the environment, of being incinerable without producing toxic gases, unlike PVC for example and be industrially recyclable.

In this context, among the reinforcements selected for petro-plastic resins, many studies have focused on the incorporation of plant fibers, especially flax and hemp fiber, cereal straw fibers, kenaf, wood fibers, cellulosic fibers (rayon), in petroleum resins such as polypropylene in particular. This produces products commonly called composites or natural fiber compounds. We can refer for example to the following thesis:

"Interfacial Interactions in Fiber Reinforced Thermoplastic Composites" by Livia Danyadi, Laboratory of Plastics and Rubber Technology Department of Physical Chemistry and Materials Science Budapest University of Technology and Economics, Institute of Materials and Environmental Chemical Chemistry Research Center Hungarian Academy of Sciences; 2009

This compounding operation is now fairly well controlled although many studies are still conducted to improve the production and characteristics of these composites. However, the introduction of such vegetable fibers is not easy considering that these plant fibers are generally both very rich in water and very hydrophilic while the resins are almost anhydrous and hydrophobic nature. In fact, it is common to introduce synthetic products, generally of petroleum origin, as dispersing agents, compatibilizing agents and / or coupling agents, between the resins and the plant fibers. Moreover, the incorporation of plant fibers into petro-plastic resins faces the problem of the high instability of plant fibers under the usual temperature and shearing conditions applied for the processing and the implementation of these petro-plastic resins. . Indeed, even in the presence of specific stabilizing agents, the plant fibers remain very sensitive to shear, heat, light and microorganisms. In addition, dehydration or drying of these fibers favorable to their incorporation or their compatibility with the resins, is accompanied by a consequent loss of their reinforcing power. In fact, in general, even by introducing amounts that may exceed 40%, the expected reinforcement of the mechanical properties of the resins by the plant fibers introduced in place of glass fibers for example, remains insufficient to be suitable for many applications. Other work has focused on the incorporation of these same plant fibers in bio-sourced resins, such as in particular polylactates (PLA). Compositions called bio-composites are thus obtained, which then have even more inadequate and unsatisfactory characteristics than composites of petro-plastics and vegetable fibers, to fulfill the specifications of a large number of applications.

In fact, the Applicant has noted that there is a need for new compositions that actually have thermomechanical properties similar to synthetic-fiber-reinforced petroleum resins or even improved properties compared to them, while maximizing short-term renewable resources such as starch and reducing energy requirements for the manufacture, transport, processing and even recycling of such compositions. After many tests, the Applicant has realized that it is preferable to follow a new and completely different way from that followed in the work done for years to prepare composites based on renewable resources having both high modules in traction, high flexural modulus and high impact resilience, assuming that it is preferable to use a bio-sourced thermoplastic composition adapted to this need and synthetic fibers of very high specific modules, rather than retaining a polyolefin reinforced with vegetable fibers or biosourced feeds.

The present invention provides a new and advantageous solution to the problems stated above by proposing new compositions based on plant material and synthetic fibers, having mechanical properties at least comparable to resins reinforced polyolefmes market.

More specifically, according to the present invention, these compositions based on plant material and synthetic fibers comprise:

at least 10% by weight and at most 95% by weight of a thermoplastic composition (a) comprising at least one polyolefin and at least one thermoplastic starch, and at least 5% by weight and at most 90% by weight of synthetic fibers (b) with a diameter of between 2 and 35 microns and with a specific modulus of between 25 and 230 GPa.mVkg.

The Applicant has indeed found after many works that, surprisingly and unexpectedly, the use of the particular thermoplastic composition (a), instead of a composition consisting solely of polyolefin, allowed against all odds to obtain properties mechanical equivalent or better. Without wishing to be bound to any theory, the Applicant believes that the thermoplastic starch behaves in the manner of a compatibilizer or coupling agent between the thermoplastic composition (a) and the synthetic fibers (b) by acting on the fiber adhesion and the compatibility of such mixtures.

In addition, the Applicant has found that the thermoplastic composition (a) has, compared with polyolefins, excellent interaction and adhesion properties vis-à-vis the synthetic fibers, especially vis-à-vis the fibers of glass or carbon, so that this thermoplastic composition (a) can also constitute a full-fledged adhesive or synthetic fiber bonding composition (b).

For the purposes of the invention, the term "thermoplastic starch" means a state in which the starch is no longer in a granular state, ie in a state where it is no longer in a semi-granular state. -crystalline characteristic of the state in which it is naturally present in the reserve organs and tissues of higher plants, in particular in cereal seeds, leguminous seeds, tubers of potatoes or cassava, roots, bulbs, stems and fruits. This natural semi-crystalline state is essentially due to the macromolecules of amylopectin, one of the two main constituents of starch. In the native state, the starch grains 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 that it has undergone. The granular starch, placed under polarized light, presents in microscopy a characteristic cross, called "Maltese cross", typical of the crystalline granular state. For a more detailed description of granular starch, see Chapter II entitled "Structure and morphology of the grain of starch" of S. Perez, in the book "Initiation to macromolecular chemistry and physico-chemistry", First edition 2000, Volume 13, pages 41 to 86, French Group of Studies and Applications of Polymers. The thermoplastic state of the starch is obtained by baking / plasticizing granular starch by incorporating water or / and a suitable plasticizer at a level generally between 15 and 35% relative to the granular starch and by supply of mechanical and thermal energy. US Pat. Nos. 5,095,054 to Warner Lambert and EP 0,497,706 B1 of the Applicant describe, in particular, this destructured thermoplastic state, with reduced or absent crystallinity due to the addition of plasticizer, and means for obtaining such thermoplastic starches. . The destructuring of the native semi-crystalline granular state of the starch to obtain amorphous thermoplastic starches can be carried out in a medium that is poorly hydrated by thermomechanical or extrusion processes, but in this case requires the presence of a plasticizer at risk. otherwise, carbonize the starch.

It is known that the combination of polyolefins and thermoplastic starch makes it possible to obtain thermoplastic compositions whose properties can be modulated by the choice of the type of starch, the nature of the plasticizer, the plasticization ratio, the incorporation of thermoplastic starch and polyolefins and the mixing process. By way of example, mention may be made of Rodriguez-Gonzalez et al., High performance LDPE / thermoplastic starch blends: a sustainable alternative to pure polyethylene, Polymer 44 (2003), pages 1517-1526.

In recent years, great progress has been made in obtaining new thermoplastic compositions with good mechanical properties in terms of stiffness, flexion and impact resilience, by the development of new processes such as those that have been the subject of WO 2009/095617,

WO 2009/095618 and WO 2009/095622 by the Applicant. However, such compositions comprising starch and a non-starchy polymer do not have the characteristics required to be suitable for uses of materials requiring high flexural or tensile modulus, good temperature resistance properties or impact resilience. high. In addition, while it is possible to incorporate reinforcing agents into polyolefin-based compositions, the addition of these to improve its mechanical properties in bending and pulling is generally accompanied by decreased impact resistance. By way of example, the Applicant has found that the addition of clay or calcium carbonate in a composition based on thermoplastic starch and polyolefin results in an improvement of the mechanical properties in flexion accompanied by a decrease in impact resilience.

The Applicant has found that by adding specific synthetic fibers (b) to a composition based on thermoplastic starch and polyolefin as a non-starchy polymer, it is possible to improve the mechanical properties in flexion and traction of this material. composition, while surprisingly increasing the impact resilience of these compositions significantly.

Compositions based on polyolefins, starch and other components among which in particular synthetic fibers and more specifically glass fibers, are already described.

This is the case of the patent application WO 2009/022195 of the company Cereplast, which describes polyolefin and starch composites, which may in general include among a long list of additives mentioned, glass fibers as reinforcements. In this document, no concrete example of embodiment of such a composition is given, nor for all the characteristics that such a composition could have. In addition, the starch is introduced into a granular state (non-thermoplastic) as a filler dispersed in the polyolefin, and this through the addition of a PEG acting compatibilizer.

Similarly, US 2006/0194902 A1 discloses a composition which comprises a polyolefin, a compatibilizer and a non-thermoplastic starch filler. The composition may optionally comprise small amounts of glass fiber or cellulose.

EP 1 265 967 discloses thermoplastic starch compositions comprising fillers in the form of inorganic particles such as calcium carbonate or pine plant fibers and optionally an additional polymer. This The latter is described as being able to be among a long list of possible products, a polyolefin. At no time in this document is there described or suggested a composition according to the present invention.

US Pat. No. 6,231,970 B1 describes compositions based on thermoplastic starch and a particular filler. This composition may optionally further comprise fibers or an additional polymer.

The composition based on plant material and synthetic fibers according to the invention is characterized in that it is advantageously in the form of granules, chips, sheets, plates, powders or fibrous mats, suitable for being shaped by pressing, thermoforming, extrusion, calendering, spinning, injection or blowing.

The composition according to the invention advantageously has a density of between 1.1 and 2.5, preferably between 1.15 and 2.10 and more preferably between 1.3 and 2.00 according to the ISO 1183 method. density is actually quite high but remains very advantageous in view of the densities of metals and even those of many synthetic polymers formulated with mineral fillers present on the market.

The composition according to the invention is also at least in part bio-sourced by the obligatory presence of thermoplastic starch. It nevertheless has excellent thermomechanical characteristics and is a very advantageous material to suit many application areas such as automotive, aeronautics, yachting or building. More precisely, she presents:

a very high tensile modulus, usually greater than 2500 MPa and better still greater than 3000 MPa, according to the ISO 527 method,

a flexural modulus which is also very high and greater than 1500 MPa, preferably greater than 3000 MPa and better still greater than 5000 MPa, according to the ISO 178 method, and excellent impact resilience, ie a non-notched Chock Charpy value exceeding 25 kJ / m ² , or even 30 kJ / m ² at 23 ° C according to the ISO method 179 / IeU or a notched Shock Charpy value usually exceeding 15 kJ / m ² , or even 20 kJ / m ² at 23 ° C according to the ISO 179 / lA method.

The composition according to the invention comprises first and foremost a particular thermoplastic composition (a) which has the advantage of being rather sparse and of having a density measured according to the ISO 1183 method of between 1.05 and 1.25 and of preferably between 1.1 and 1.2. This thermoplastic composition (a) necessarily comprises a polyolefin. This polyolefin may be virgin, that is to say not having any prior use, although it may be formulated by the addition of additives or by compounding. It can also be recycled, that is to say come from polyolefin parts or objects recovered by recovery of material.

This polyolefin is preferably chosen from high density polyethylenes (HDPE), low density polyethylenes (LDPE), linear low density polyethylenes, homopolymeric polypropylenes (PPh), random polypropylenes (PPs), polypropylene copolymers (PPc) and polybutenes, as well as any mixtures thereof.

The polyolefin may in particular be a mixture of polyolefins, at least one of which may carry silane, acrylic or maleic anhydride units, hereinafter functional units. Preferably, the amount by mass of silane, acrylic or maleic anhydride units ranges from 0.1 to 10% of the total mass of the polyolefin with patterns. It may be in particular polyolefins grafted with maleic anhydride.

According to one embodiment, the polyolefin comprises from 10 to 90% by weight of a polyolefin without functional units, or even from 25 to 75%, and from 10 to 90% by weight of a polyolefin carrying functional units. or even 25 to 75%.

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

The polyolefin of the composition is preferably semi-crystalline. At least one of its melting temperatures is then advantageously between 100 and 200 ° C., preferably between 110 and 170 ° C. The melting temperature can be measured in a known manner by differential scanning calorimetry (DSC) with a heating rate of 10 ° C / minute: this measurement can be carried out by first heating the sample up to 200 ° C., cooling to a temperature of -50 ° C and then a second heating of the sample during which the melting temperature is measured, the heating and cooling rates being 10 ° C / minute.

Preferably, the polyolefin of the thermoplastic composition (a) is a polymer containing at least 50%, preferably at least 70%, in particular more than 80%, and more preferably 100% of carbon of renewable origin in the sense of the ASTM D 6852 and / or ASTM D 6866, with respect to all the carbon present in said polymer. The thermoplastic composition (a) may therefore comprise at least one polyolefin obtained from bio-sourced monomers, in particular from bioethanol or bio-methanol or bio-sourced functionalization grafts.

The thermoplastic composition (a) also necessarily comprises a thermoplastic starch. This starch preferably has a degree of crystallinity of less than 15%, preferably less than 5% and more preferably less than 1%, that is to say being in a substantially amorphous state.

This degree of crystallinity can in particular be measured by X-ray diffraction as described in US Pat. No. 5,362,777 (column 9, lines 8 to 24).

The thermoplastic starch is advantageously substantially free of starch grains having, under light microscopy under polarized light, a Maltese cross, an indicator sign of the presence of crystalline granular starch.

The thermoplastic composition (a) preferably comprises at least one thermoplastic starch representing, by dry weight, more than 25%, preferably more than

35%>, and more preferably more than 50%> of the thermoplastic composition (a), the complement to 100% of the thermoplastic composition (a) being essentially a polyolefin or a mixture of polyolefins. Usually, the polyolefin constitutes the continuous dispersing phase and the thermoplastic starch the discontinuous dispersed phase of the thermoplastic composition (a), The starch used for the preparation of the thermoplastic starch composition is preferably selected from granular starches, water-soluble starches and organomodified starches.

According to a first variant, the starch selected for the preparation of the thermoplastic starch is a granular starch. The crystallinity of said granular starch can be reduced to less than 15% by thermomechanical treatment and / or intimate mixing with a suitable plasticizer. Said granular starch can be of 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 soya, starches rich in amylose or conversely, rich in amylopectin (vaxy) from these plants and any mixtures of the aforementioned starches. The granular starch may also be a granular starch modified by any means, physical, chemical and / or enzymatic. It may be a fluidized or oxidized granular starch or a white dextrin. It may also be a granular starch modified physico-chemically but having been able to retain the structure of the native starch starch, such as esterified and / or etherified starches, in particular modified by grafting, acetylation, hydroxypropylation, anionization, cationisation, crosslinking, phosphatation, succinylation and / or silylation. It may be, finally, a starch modified by a combination of the treatments mentioned above or any mixture of such granular starches.

In a preferred embodiment, this granular starch is chosen from native starches, fluidized starches, oxidized starches, chemically modified starches, white dextrins and any mixtures of these products.

The granular starch is preferably a wheat or pea granular starch or a granular derivative of wheat or pea starch. It generally has a level of solubles at 20 ° C in demineralised water of less than 5% by mass and can be practically insoluble in cold water. According to a second variant, the starch selected for the preparation of the thermoplastic starch is a water-soluble starch, which can also come from all botanical origins, including a starch, which is water-soluble, rich in amylose or, conversely, rich in amylopectin (waxy). . This soluble starch can be introduced as a partial or total replacement of the granular starch.

For the purposes of the invention, the term "water-soluble starch" means any polysaccharide material derived from starch, having at 20 ° C. and with mechanical stirring for 24 hours, a fraction soluble in demineralised water at least equal to 5% in weight. This soluble fraction is preferably greater than 20% by weight and in particular greater than 50% by weight. Of course, the soluble starch can be totally soluble in demineralized water (soluble fraction = 100%).

The water-soluble starch is used in solid form, preferably substantially anhydrous, i.e. undissolved or non-dispersed in an aqueous or organic solvent. It is therefore important not to confuse, throughout the description that follows, the term "water-soluble" with the term "dissolved".

Such water-soluble starches can be obtained by pregelatinization on a drum, by pregelatinization on an extruder, by spraying a suspension or a starch solution, by precipitation with a non-solvent, by hydrothermal cooking, by chemical functionalization or the like. It is in particular a pregelatinized, extruded or atomized starch, a highly converted dextrin (also called yellow dextrin), a maltodextrin, a functionalized starch or a mixture of these products.

The pregelatinized starches can be obtained by hydrothermal treatment of gelatinization of native starches or modified starches, in particular by steam cooking, jet-cooker cooking, drum cooking, cooking in kneader / extruder systems and then drying, for example in incubator, by hot air on a fluidized bed, on a rotating drum, by atomization, by extrusion or by lyophilization. Such starches generally have a solubility in demineralized water at 20 ° C. of greater than 5% and more generally of between 10 and 100% and a starch crystallinity level of less than 15%, generally less than 5% and most often less than 1%, or even none. Examples include products manufactured and marketed by the Applicant under the brand name PREGEFLO ^®.

Highly processed dextrins can be prepared from native or modified starches by dextrinification in a weakly acidic acid medium. It may be in particular soluble white dextrins or yellow dextrins. By way of example, mention may be made of the STABILYS ^® A 053 or TACKIDEX ^® C 072 products manufactured and marketed by the Applicant. Such dextrins have demineralized water at 20 ° C, a solubility generally between 10 and 95% and a starch crystallinity of less than 15% and generally less than 5%.

Maltodextrins can be obtained by acid, oxidative or enzymatic hydrolysis of starches in an aqueous medium. They may in particular have an equivalent dextrose (DE) of between 0.5 and 40, preferably between 0.5 and 20 and better still between 0.5 and 12. Such maltodextrins are for example manufactured and marketed by the Applicant under the trade name GLUCIDEX ^® and have a solubility in deionized water at 20 ° C, generally greater than 90% or close to 100% and a starch crystallinity generally less than 5% and usually almost zero.

The functionalized starches can be obtained from a native or modified starch. The high functionalization may for example be carried out by esterification or etherification at a sufficiently high level to confer a solubility in water. Such functionalized starches have a soluble fraction as defined above, greater than 5%, preferably greater than 10%, more preferably greater than 50%.

The functionalization can be obtained in particular by aqueous phase acetylation of acetic anhydride, mixed anhydrides, glutamate hydroxypropylation, dry phase cationization or glue phase, anionization in the dry phase or glue phase by phosphatation or succinylation. These water-soluble highly functionalized starches may have a degree of substitution of between 0.01 and 3, and more preferably between 0.05 and 1. Preferably, the reagents for modifying or functionalizing the starch are of renewable origin. According to another advantageous variant, the water-soluble starch is a water-soluble starch of wheat or pea or a water-soluble derivative of a wheat or pea starch.

It advantageously has a low water content, generally less than 10%, preferably less than 5%, in particular less than 2% by weight and ideally less than 0.5%, or even less than 0.2% by weight.

According to a third variant, the starch selected for the preparation of the thermoplastic starch is an organomodified starch, preferably organosoluble, which may also come from all botanical origins, including an organomodified starch, preferably organosoluble, rich in amylose or, conversely , rich in amylopectin (waxy). This organosoluble starch may be introduced as partial or total replacement of the granular starch or of the water-soluble starch.

For the purposes of the invention, the term "organomodified starch" means any polysaccharide material derived from starch, other than a granular starch or a water-soluble starch according to the definitions given above. Preferably, this organomodified starch is almost amorphous, that is to say has a starch crystallinity level of less than 5%, generally less than 1% and especially zero. It is also preferably "organosoluble", that is to say present, at 20 ° C, a fraction soluble in a solvent selected from ethanol, ethyl acetate, propyl acetate, butyl acetate, diethyl carbonate, propylene carbonate, dimethyl glutarate, triethyl citrate, dibasic esters, dimethyl sulfoxide (DMSO), dimethyl isosorbide, glycerol triacetate, isosorbide diacetate, dioleate isosorbide and methyl esters of vegetable oils, at least equal to 5% by weight. This soluble fraction is preferably greater than 20% by weight and in particular greater than 50% by weight. Of course, the organosoluble starch may be totally soluble in one or more of the solvents indicated above (soluble fraction = 100%).

The organomodified starch may be used according to the invention in solid form, preferably substantially anhydrous. Preferably, its water content is less than 10%, preferably less than 5%, in particular less than 2% by weight and ideally less than 0.5%, or even less than 0.2% by weight.

The organomodified starch that can be used in the composition according to the invention can be prepared by high functionalization of the native or modified starches such as those presented above. This high functionalization can for example be carried out by esterification or etherification at a sufficiently high level to make it essentially amorphous and to confer on it an insolubility in water and preferably a solubility in one of the above organic solvents. Such functionalized starches have a soluble fraction as defined above, greater than 5%, preferably greater than 10%, more preferably greater than 50%.

The high functionalization can be obtained in particular by acetylation in the solvent phase by acetic anhydride, grafting for example in the solvent phase or by reactive extrusion, of acid anhydrides, mixed anhydrides, fatty acid chlorides, oligomers of caprolactones or lactides, hydroxypropylation and crosslinking in the glue phase, cationization and crosslinking in the dry phase or in the glue phase, anionization by phosphatation or succinylation and crosslinking in the dry phase or in the glue phase, sililation, butadiene telomerization. These organomodified, preferably organosoluble, highly functionalized starches may in particular be acetates of starches, dextrins or maltodextrins or fatty esters of these starchy materials (starches, dextrins, maltodextrins) with fatty chains of 4 to 22 carbons, all of these products preferably having a degree of substitution (DS) between 0.5 and 3.0, preferably between 0.8 and 2.8 and in particular between 1.0 and 2.7.

It may be, for example, hexanoates, octanoates, decanoates, laurates, palmitates, oleates and stearates of starches, dextrins or maltodextrins, in particular having a DS between 0 , 8 and 2.8.

According to another advantageous variant, the organomodified starch is an organomodified starch of wheat or pea or an organomodified derivative of a wheat or pea starch.

Preferably, the thermoplastic composition (a) comprises a plasticizer. The term "plasticizer" is intended to mean any organic molecule of low molecular weight, that is to say preferably having a molecular weight of less than 5000, which, when incorporated by a thermomechanical treatment at a temperature of between 20 and 200 ° C to the thermoplastic composition (a) or to the thermoplastic starch, results in a decrease in the glass transition temperature of the thermoplastic composition (a) or the thermoplastic starch and / or results in reducing the crystallinity of the thermoplastic starch until it reaches an essentially amorphous state.

The thermoplastic composition (a) preferably has a content of plasticizer in dry weight of between 4% and 50%, preferably between 8% and 40% and in particular between 15% and 25%, of the thermoplastic composition ( at).

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 and mixtures of these products.

The plasticizer preferably selected in the context of the present invention is preferably chosen from diols, triols and polyols such as glycerol, polyglycerol, isosorbide, sorbitans, sorbitol, mannitol, and syrups of hydrogenated glucose, salts of organic acids such as sodium lactate, urea and mixtures of these products. The plasticizer then advantageously has a molar mass of less than 5000, preferably less than 1000, and in particular less than 400. The plasticizer preferably has a molar mass of greater than 18 and at most 380, ie preferably does not include water.

The plasticizer of the starch may be, especially when the latter is organomodified, chosen from methyl, ethyl or fatty esters of organic acids such as lactic acid, citric acid, succinic acid, adipic acid and glutaric acid and the acetic acid esters. fatty esters of monoalcohols, diols, triols or polyols such as ethanol, diethylene glycol, glycerol and sorbitol. By way of example, mention may be made of glycerol diacetate (diacetin) and glycerol triacetate. (triacetin), isosorbide diacetate, isosorbide dioctanoate, isosorbide dioleate, isosorbide dilaurate, dibasic esters (dibasic esters of dicarboxylic acids or dibasic esters), and mixtures of these products.

The plasticizer, preferably other than water, is generally present in the thermoplastic starch at a rate of 1 to 150 parts by dry weight, preferably at 10 to 120 parts by dry weight and in particular at 25 to 25 parts by weight. 120 parts by dry weight per 100 parts by dry weight of starch.

Thus, according to an advantageous variant, the plasticizer, preferably other than water, is contained in the thermoplastic starch at 25 to 110 parts by dry weight, preferably at 30 to 100 parts by dry weight, and in particular from 30 to 90 parts by dry weight, per 100 parts by dry weight of starch.

The thermoplastic composition (a) preferably comprises, as thermoplastic starch, at least one plasticized starch obtained from native starches, pregelatinized starches, extruded starches, atomized starches, fluidized starches, oxidized starches, cationic starches, anionic starches, hydroxyalkylated starches, crosslinked starches, starch acetates, starch fatty esters and fatty chains of 4 to 22 carbons, dextrins , maltodextrins and any mixtures of these products, plasticized by at least one of the plasticizers listed above.

In addition, the thermoplastic composition (a) advantageously comprises: from 25 to 85% by weight of thermoplastic starch,

from 10 to 60% by weight of polyolefin,

and from 4 to 40% by weight of at least one plasticizer, preferably other than water, and more preferably:

from 35 to 85% by weight of thermoplastic starch, for example from 35 to 80%,

from 10 to 50% by weight of polyolefin,

and from 10 to 30% by weight of at least one plasticizer, preferably other than water.

The composition according to the invention also preferably comprises a binding agent.

The term "linking agent" in the present invention means any organic molecule carrying at least two functional groups, free or masked, capable of reacting with molecules carrying active hydrogen functions such as starch or plasticizer of starch. This binding agent may be added to the composition to allow covalent attachment of at least a portion of the plasticizer to the starch or even to the polyolefin, particularly if it carries functional groups.

This binding agent can then be chosen for example from compounds carrying at least two functions, free or masked, identical or different, chosen from isocyanate functions, carbamoylcaprolactams, aldehydes, epoxides, halo, protonic acids, acid anhydrides acyl halides, oxychlorides, trimetaphosphates, alkoxysilanes and combinations thereof.

It can advantageously be chosen from 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-caprolactam,

glyoxal, dialdehyde starches and TEMPO oxidized starches,

diepoxides,

halohydrins, that is to say compounds having an epoxide function and a halogen function, preferably epichlorohydrin,

organic diacids, preferably succinic acid, adipic acid, glutaric acid, oxalic acid, malonic acid, maleic acid and the corresponding anhydrides,

the oxychlorides, preferably phosphorus oxychloride,

trimetaphosphates, preferably sodium trimetaphoshate,

alkoxysilanes, preferably tetraethoxysilane, and

any mixtures of these compounds. In a preferred embodiment of the invention, the linking agent is a diisocyanate, in particular methylenediphenyl diisocyanate (MDI) or 4,4'-dicyclohexylmethane diisocyanate (H 12 MDI).

The amount of binding agent, expressed as dry weight and relative to the sum, expressed in dry weight of the composition according to the invention is advantageously between 0.1 and 15% by weight, preferably between 0.1 and 12. % by weight, more preferably still between 0.2 and 9% by weight and in particular between 0.5 and 5% by weight.

The optional but preferred incorporation of the binding agent into the mixture of the composition according to the invention can be done by physical mixing at low temperature or cold, but preferably by hot mixing at a temperature above the transition temperature. vitreous of the amylaceous composition. This mixing temperature is advantageously between 60 and 200 ° C. and better still between 100 and 180 ° C. This incorporation can be carried out by thermomechanical mixing, discontinuously or continuously and in particular online. In this case, the mixing time can be short, from a few seconds to a few minutes.

The composition according to the invention may preferably comprise an agent improving its impact resilience, especially at a temperature of 23 ° C. or at a lower temperature. It may be an ethylene-propylene co-polymer type polymer (in particular ethylene-propylene terpolymer (EPDM)), ethylene-styrene, styrene-butadiene, a natural rubber, a copolymer-type elastomer styrene-butylene-styrenes (SB S) and styrene-ethylene-butylene-styrenes (SEBS) or any other elastomeric material. This improving agent may represent from 1 to 15%, preferably 2 to 12% and better still 5 to 10% of the composition according to the invention.

The thermoplastic composition (a) advantageously has the following preferred variants, taken separately or in combination:

the thermoplastic starch is derived from granular starches, water-soluble starches or organomodified starches, preferably wheat or peas.

the thermoplastic starch has a degree of crystallinity of less than 5%, preferably less than 1%, that is to say in a substantially amorphous state, the polyolefin is chosen from polyethylenes (PE) and polypropylenes (PP), and preferably contains several polyolefins, at least one of which is functionalized, that is to say carries functional groups such as silane, acrylic or maleic anhydride units; ,

the polyolefin is a polymer containing at least 50%, preferably at least 70%, in particular more than 80%, and better still 100% of renewable carbon according to ASTM D 6852 and / or ASTM D 6866, with respect to all the carbon present in said polymer,

the thermoplastic composition (a) comprises at least one plasticizer chosen from diols, triols and polyols such as glycerol, polyglycerol, isosorbide, sorbitans, sorbitol, mannitol, and hydrogenated glucose syrups, salts of organic acids such as sodium lactate, urea and mixtures of these products,

the thermoplastic composition (a) comprises at least one impact-resilience improving agent, chosen in particular from polymers of ethylene-propylene co-polymer, ethylene-styrene or styrene-butadiene type, natural rubbers, elastomers of the type styrene-butylene-styrene copolymer (SB S) and styrene-ethylene-butylene-styrenes (SEBS) or any other elastomeric material,

the thermoplastic composition (a) comprises at least one linking agent chosen from compounds bearing at least two functions, free or masked, identical or different, chosen from isocyanate, carbamoylcaprolactam, aldehyde, epoxide, halogen and protonic acid functions; acid anhydride, acyl halide, oxychloride, trimetaphosphate, alkoxysilane and combinations thereof,

the thermoplastic composition (a) contains at least 30%, advantageously at least 51%, preferably at least 70%, in particular more than 80% of carbon of renewable origin according to ASTM D 6852 and or ASTM D 6866, with respect to all the carbon present in said composition, the thermoplastic composition is non-biodegradable or non-compostable in the sense of the standards EN 13432, ASTM D 6400 and ASTM D 6868,

or the thermoplastic composition has a maximum flexural stress greater than 50 MPa, preferably greater than 100 MPa.

The composition according to the invention in the second place necessarily comprises synthetic fibers (b). These fibers are chosen so as to have a diameter of between 2 and 35 microns and a specific modulus of between 25 and 230 GPa.m3 / kg and selected in order to improve the cold mechanical properties of the composition according to the invention but also its heat stability as well as its thermomechanical properties, its conductive properties, and / or its organoleptic properties such as its appearance, color or odor. They may also be chosen advantageously to increase the nucleation or the crystallizability of the polyolefin present in the thermoplastic composition (a) and to allow the properties to be adjusted to the shrinkage of the composition according to the invention.

They may in particular be chosen from glass fibers, carbon fibers, metal fibers and synthetic polymer fibers having a melting temperature measured by DSC greater than 180 ° C. and preferably greater than 200 ° C. and / or temperature HDT (Heat Deflexion Temperature, ISO 75 Bf method at 0.45 MPa) greater than 70 ° C and preferably greater than 100 ° C, and more particularly be chosen from short glass fibers, long glass fibers, high tenacity carbon fibers, high modulus carbon fibers, low modulus aramid fibers, modulus high fibers, polyethylene terephthalate (PET) fibers, polybutylene terephthalate (PBT) fibers, polypropylene (PP) fibers, polystyrene fibers (PS), polyamide fibers (in particular PA 6, PA 4-6, PA 6-6, aromatic PA), polyurethane fibers (PU, TPU), PLA fibers (in particular stéréocompl exes PLLA / PDLA).

The composition according to the invention advantageously comprises, when it is intended to be shaped according to a conventional technique used in plastics, between 10% and 60% by weight, for example between 10 and 40%, or between 15 and 30% of synthetic fibers (b). The amount by weight of these synthetic fibers (b) may advantageously be between 20 and 50%, or even between 25 and 45%. The composition according to the invention then preferably has a low melt flow, that is to say preferably an MFR between 1 and 100 g / 10 minutes and better between 2 and 50 g / 10 minutes, at 190 ° C for a mass of 2.16 kg according to the ISO 1133 method.

On the other hand, when the composition according to the invention is intended to be shaped according to a conventional technique used in the textile industry, it advantageously contains from 40% to 90% by weight, preferably 60% to 90% by weight. and more preferably from 70% to 90% by weight of synthetic fibers (b). In this case, the thermoplastic composition (a) is advantageously used as a binder, an adhesive agent, a sizing agent, an impregnating agent, a sheathing agent or a sizing agent for synthetic fibers (b). ). It then preferably has a high fluidity in the molten state, that is to say preferably an MFR of between 25 and 500 g / 10 minutes and better still between 100 and 500 g / 10 minutes, at 190 ° C. for a mass of 2.16 kg according to the ISO 1133 method.

These synthetic fibers (b) advantageously have a diameter of between 2 and 35 microns, preferably between 5 and 30 microns, and more preferably between 8 and 15 microns. When it comes to glass fibers, the diameter of the elementary fiber is usually between 3 and 30 microns and more typically between 10 and 14 microns. With regard to short glass fibers, their length generally of the order of 3 to 4 millimeters at the introduction, is usually close to 200 to 300 microns in the composition according to the invention. For so-called long fibers, their length can reach several millimeters to tens of centimeters in the composition of the present invention. These synthetic fibers (b) moreover preferably have a tensile rupture modulus of between 60 and 450 GPa and more advantageously of between 70 and 400 GPa.

Furthermore, the composition according to the invention may comprise other polymers, of any kind, in small quantities, for the adjustment of its characteristics. However, it will preferably include polymers or copolymers, partially or totally bio-sourced, such as in particular polyurethanes (PU), thermoplastic polyurethanes (TPU), polyamides, polyesters, especially polybutyleneterephthalates (PBT), polyethylene terephthalate (PET), copolyester-co-terephthalates aliphatic (PBAT), polylactates (PL A), polybutylenes succinates (PB S, PB SA), polyhydroxyalkanoates (PHA, PHB, PHBV).

Fillers and other additives of all kinds, including those detailed below, may also be incorporated in the composition of the present invention.

It may be products intended to further improve its physico-chemical properties, in particular its physical structure, its implementation behavior and its durability or its mechanical, thermal, conductive, adhesive or organoleptic properties.

The additive may be an improving agent or an adjustment of the mechanical or thermal properties chosen from minerals, salts and organic substances. It may be nucleating agents such as talc, compatibilizers or dispersants such as natural or synthetic surfactants, impact or scratch-resistant agents such as calcium silicate control agents such as magnesium silicate, scavengers or deactivators of water, acids, catalysts, metals, oxygen, infrared rays, UV rays, hydrophobing agents such as oils and greases, fire retardants and flame retardants such as halogenated derivatives, smoke-suppressing agents, reinforcing fillers, mineral or organic, such as calcium carbonate, talc.

The additive 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. , to solvents, to fatty substances, to essences, to aromas, to perfumes, chosen in particular from minerals, salts and organic substances, in particular from heat-conduction or dissipation agents such as metal powders and graphites . This heat dissipation agent may also be chosen from ceramics. The additive may be an agent that improves the organoleptic properties, in particular:

- odorous properties (perfumes or odor masking agents),

optical properties (brighteners, whiteners such as titanium dioxide, dyes, pigments, dye enhancers, opacifiers, matting agents such as calcium carbonate, thermochromic agents, phosporescence and fluorescence agents, agents metallizers or marbles and anti-fogging agents),

- sound properties (barium sulphate and barytes), and

- tactile properties (fats, silicone oils).

The additive 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, rosins, ethylene / vinyl alcohol copolymers, fatty amines, lubricating agents, mold release agents, antistatic agents and anti-blocking agents.

Finally, the additive may be an agent improving the durability of the material or an agent for controlling its (bio) degradability, especially chosen from hydrophobic or pearling 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.

Preferably, the additive may be selected from aging stabilizers, in particular UV stabilizers, hydrophobing agents and antimicrobial agents.

With a view to the preparation of the composition according to the invention, it is possible to use a number of methods that provide for extremely varied moments and orders of introduction of the components of said composition (polyolefin, starch, optional plasticizer, synthetic fibers (b), optional bonding agent, impact resilience enhancer, other optional additives).

Thus, the synthetic fibers may be introduced after all or part of it has been previously dispersed in the thermoplastic composition (a).

Among all these possibilities of implementing said components, the present invention particularly relates to a process for the advantageous preparation of a composition as described above in all its variants, said process comprising the following steps:

(i) selecting at least one thermoplastic composition (a) comprising at least one polyolefin and at least one thermoplastic starch,

(ii) selecting at least one type of synthetic fiber (b) with a diameter of between 2 and 35 microns and a specific modulus of between 25 and 230 GPa.mVkg,

(iii) mixing, preferably thermomechanical mixing, the thermoplastic composition (a) and synthetic fibers (b) so as to obtain the composition based on plant material and synthetic fibers.

Incorporation of synthetic fibers (b) into the thermoplastic composition

(a) or the application of the thermoplastic composition (a) to synthetic fibers

(b) can be performed cold and prior to its thermomechanical mixing. This mixture is ideally carried out hot, that is to say at a temperature above the glass transition temperature of the highest thermoplastic composition (a). This temperature may be between 60 and 280 ° C., for example between 60 and 250 ° C., more preferably between 80 and 200 ° C. and in particular between 100 and 185 ° C. The temperature may be high enough to facilitate the incorporation of the fibers into the thermoplastic composition, for example between 200 and 280 ° C, preferably between 220 and 270 ° C. The thermomechanical mixture can be produced discontinuously, for example by kneading / kneading, or continuously, for example by extrusion or coextrusion. The duration of this mixture can range from a few seconds to a few hours, depending on the mixing mode selected. Preferably, the duration the mixture ranges from a few seconds to a few minutes, for example from 10 to 75 seconds.

According to a preferred method of the invention, glass fibers are selected as synthetic fibers in step (ii) and the mixture of step (iii) is carried out by extrusion at a temperature of between 200 and 280 ° C. preferably between 220 and 270 ° C. In these temperature ranges, it is possible to disperse the glass fibers (b) in a very homogeneous manner in the thermoplastic composition (a). However, when thermoplastic starch is extruded alone at temperatures above 200 ° C, there is a strong loss of the mechanical properties of this thermoplastic starch, this loss being related to the thermal degradation of the starch and the plasticizer. This degradation is even more important when attempting to incorporate glass fibers in this thermoplastic starch, because of the sharp increase in viscosity during this incorporation. Surprisingly, although the thermoplastic composition (a) comprises thermoplastic starch which is thermally unstable, the method of manufacturing the composition is carried out without difficulty and the mechanical properties of the composition obtained by this method are excellent.

The Applicant has shown that the process according to the invention is, compared with the conventional process for producing polyolefin-based composites and fibers, very advantageous in terms of energy, because of the choice of the particular thermoplastic composition (a) and the presence therein of thermoplastic starch.

The process according to the invention may comprise a step which is subsequent to or concomitant with the mixing step (iii), namely a shaping treatment of the composition based on plant material and synthetic fibers (iv), at a temperature between 60 and 280 ° C, for example between 80 and 250 ° C, preferably between 120 and 200 ° C, and in particular between 160 and 185 ° C.

The subject of the present invention is also the use of a composition comprising at least one at least partially plasticized starch as a compatibilizing agent between synthetic fibers (b) and a polyolefin. The thermoplastic composition according to the invention can be used as such or in admixture with other products or additives, including other synthetic, artificial or naturally occurring polymers. It is preferably non-biodegradable and non-compostable in the sense of standards EN 13432, ASTM D 6400 and ASTM D 6868, and thus constitute a sink or carbon trap, thanks to its high content of plant products of photosynthetic origin.

The composition according to the invention advantageously contains at least 25%, preferably at least 30%, and in particular more than 40% of material of renewable origin according to the ASTM D 6866 renewable carbon determination method, expressed by relative to the whole of said composition. This carbon of renewable origin is that constitutive of the starch necessarily present in the composition according to the invention but can also be that of the polyolefin which is preferably bio-sourced, that of the other possible constituents of the composition such as the plasticizer, especially if it is glycerol or sorbitol, or any other product when it comes from renewable natural resources.

It is in particular possible to use the compositions according to the invention, as bioplastic materials or composite materials, useful for the preparation by injection, extrusion, blowing, calendering, molding, thermoforming, compacting, spinning, coring or other techniques , objects, parts, bottles, jars, containers, tanks, sheets, panels, bars, cleats, beam profiles, tables, indoor furniture, street furniture, masts, nonwovens, door trim, walls, insulation layers, automotive parts, electrical parts, wiring, ducts, dashboards, hoods or other household products such as sports and leisure items, household appliances, tools or useful for different industries such as the building, packaging, electricity, transportation, aeronautics and yachting industries and the eq uipement.

Said composition may be in pulverulent, granulated or bead form. It can constitute as such a masterbatch or the matrix of a masterbatch, intended to be diluted in a bio-sourced matrix or not. She can also constitute a plastic raw material or a compound that can be used directly by an equipment manufacturer or a manufacturer of plastic objects. It can also constitute a final or intermediate composition, suitable for being shaped or used in the textile industry as a fibrous mat or a nonwoven, or in the wood-processing industry such as a wood panel or wood composites. / polymers.

The invention will be better understood in the light of the following examples, which are in no way intended to limit the invention.

Example: Compositions according to the invention and according to the prior art

Preparation of compositions

For this example, the thermoplastic composition (a) is a composition based on:

- 52% by weight of the composition called "AP6040" as described in the aforementioned patent applications WO 2009/095617, WO 2009/095618 and WO 2009/095622, filed by the Applicant,

46% by weight of a polyolefin consisting of one half of commercial polypropylene and, for the other half, of maleic anhydride grafted polypropylene, and about 2% of methylenediphenyl diisocyanate (MDI).

This composition comprises 52% of renewable origin material in the form of wheat starch and bio-sourced polyol type plasticizers. It has a density close to 1.11 and an MFR of 26 g / 10 minutes at 190 ° C. for a mass of 10 kg. This thermoplastic composition (a) is referred to as: Resin A.

A composition according to the invention (Essail) is prepared using only Resin A as thermoplastic composition (a) and as synthetic fibers (b), glass fibers having:

a specific module close to 30 GPa.mVkg,

a specific stress close to 1 GPa.mVkg,

a tensile stress of 2.2 GPa, a tensile modulus of 75 GPa,

an elongation at break of 4.8%,

and a diameter of the elementary fiber of 10 microns. Approximately 40% by weight of glass fiber is mixed with the thermoplastic resin composition A.

The conditions of preparation by extrusion die 6 mm are as follows:

increasing temperature profile from 240 ° C to 260 ° C .;

- impregnation die specific to the long fibers process;

- flow 200kg / h.

At the extruder outlet, the rods are cooled under water, then cut to 1cm long. The density of the composition according to the invention thus obtained is close to 1.25. A control composition called G400-8229 is prepared in an identical manner with an identical glass fiber content of about 40%, using, instead of Resin A, a mixture comprising 97% of a polypropylene mixture. MFR PPH60 homopolymer homopolymer of 60 g / 10 min (230 ° C, 2.16 kg) and a polypropylene homopolymer PPH450 of MFR of 450 g / 10 min (230 ° C, 2.16 kg) and 3% of 1% maleic anhydride grafted polypropylene (PPg) as a compatibilizer. Only the die extrusion conditions of 6mm are slightly modified in the sense that the profile is increasing from 280 ° C to 300 ° C.

A composition according to the invention (Test 2) identical to the control composition G400-8229 is also prepared, with the same method as in Test 1, except that Resin A replaces PPH60.

Under the same conditions and relative proportions of PPH450, Resin A and PPg as those of Test 2, a composition according to the invention is finally prepared (Test 3), with the difference that the quantity of glass fibers is 30% by weight. The industrial tests did not pose any particular problem when using Resin A in place of the PPH mixture, except that for Test 1, the melt is a little too viscous and leads to broken fiberglass.

Mechanical characteristics of the compositions according to the invention and according to the prior art:

It is observed that the compositions according to the invention have at glass fiber equivalence, very good mechanical properties and that the composition according to Test 2 is comparable or better than the composition according to the prior art for the measured criteria.

Resin A appears to act both on the improvement of adhesion to glass fibers and on the improvement of the compatibility of these fibers with polypropylene. The composition according to the invention may also be obtained by the same method as that usually applied and advantageously without modification of the tooling and working at temperatures below 20 to 35 ° C below the control composition. This advantageously allows significant energy savings and reduce the need for fossil resources.

In addition, the composition according to the invention, unlike that of the prior art, has a natural appearance. It also has a pleasant feel explained by the presence of starch in the thermoplastic composition (a) and thus to overcome the use for this purpose of a synthetic elastomer.

It is found that the composition Test 1 according to the invention comprising in total about 31% of bio-sourced material, that the composition Test 2 according to the invention comprising in total about 16% of bio-sourced material and that the composition Test 3 also according to the invention comprising a total of about 18% of biobased material all have many technical advantages compared to the control composition according to the prior art which has no renewable natural origin at all.

As explained above, the addition of reinforcements in a composition to improve its mechanical properties in flexion and traction is generally accompanied by a decrease in impact resistance. By way of example, the Applicant has found that by adding clays or calcium carbonate in a composition based on thermoplastic starch and polyolefin, the mechanical properties in flexion and in traction of this composition were improved but a decrease impact resilience was also observed.

By comparing the properties obtained for the compositions according to the invention with the composition without glass fibers (Resin A), the Applicant has thus found that by adding specific synthetic fibers to a composition based on thermoplastic starch and polyolefin, it is possible to improve the mechanical properties in flexion and traction of this composition, while increasing in a manner surprisingly the impact resistance of these compositions based on polyolefin and thermoplastic starch.

Claims

1. Composition based on plant material and synthetic fibers characterized in that it comprises:

at least 10% by weight and at most 95% by weight of a thermoplastic composition (a) comprising at least one polyolefin and at least one thermoplastic starch and at least 5% by weight and at most 90% by weight of synthetic fibers (b) with a diameter of between 2 and 35 microns and a specific modulus of between 25 and 230 GPa.mVkg.

2. Composition according to claim 1, characterized in that it is in the form of granules, chips, sheets, plates, powders or fibrous mats, capable of being shaped by pressing, thermoforming, extrusion, calendering, spinning, injection or blowing.

3. Composition according to claim 1 or 2, characterized in that the thermoplastic composition (a) has a density of between 1.1 and 2.5, preferably between 1.15 and 2.10 and more preferably between 1, 3 and 2.0 according to the method ISO 1183.

4. Composition according to any one of the preceding claims, characterized in that it has a flexural modulus greater than 1500 MPa, preferably greater than 3000 MPa and better than 5000 MPa, according to the ISO 178 method.

5. Composition according to any one of the preceding claims, characterized in that the thermoplastic composition (a) comprises at least one polyolefin, virgin or recycled, selected from high density polyethylenes (HDPE), low density polyethylenes (LDPE), linear low density polyethylenes, homopolymeric polypropylenes (PPh), statistical polypropylenes (PPs), polypropylene copolymers (PPc) and polybutenes, as well as any mixtures thereof.

6. Composition according to any one of the preceding claims, characterized in that the thermoplastic composition (a) comprises at least one polyolefin obtained from bio-sourced monomers, in particular from bioethanol or bio-methanol.

7. Composition according to any one of the preceding claims, characterized in that the thermoplastic composition (a) comprises thermoplastic starch whose crystallinity level is less than 15%, preferably less than 5% and more preferably less than 15%. 1%.

8. Composition according to any one of the preceding claims, characterized in that the thermoplastic composition (a) comprises at least one thermoplastic starch representing, by dry weight, more than 25%, preferably more than 35% and more preferably more than 50% by weight. % of the thermoplastic composition (a).

9. Composition according to any one of the preceding claims, characterized in that the thermoplastic composition (a) comprises, as thermoplastic starch, at least one plasticized starch obtained from native starches, pregelatinized starches, extruded starches, atomized starches, fluidized starches, oxidized starches, cationic starches, anionic starches, hydroxyalkylated starches, crosslinked starches, starch acetates, starch and fatty chains of 4 to 22 carbons, dextrins, maltodextrins and any mixtures of these products.

10. Composition according to any one of the preceding claims, characterized in that the thermoplastic composition (a) comprises at least one plasticizer, preferably selected from diols, triols, polyols, syrups and the like. hydrogenated glucose, organic acid salts, urea, methyl, ethyl or fatty esters of organic acids, acetic or fatty esters of monoalcohols, diols, triols or polyols and any mixtures of these products.

11. Composition according to any one of the preceding claims, characterized in that the thermoplastic composition (a) has a plasticizer content in dry weight of between 4% and 50%, preferably between 8% and 40% and in particular between 15% and 25% of the thermoplastic composition (a).

12. Composition according to any one of the preceding claims, characterized in that within the thermoplastic composition (a), the polyolefin constitutes the continuous dispersing phase and the thermoplastic starch discontinuous dispersed phase.

13. Composition according to any one of the preceding claims, characterized in that the thermoplastic composition (a) comprises:

from 25 to 85% by weight of thermoplastic starch,

from 10 to 60% by weight of polyolefin,

and from 4 to 40% by weight of at least one plasticizer, preferably other than water.

14. Composition according to any one of the preceding claims, characterized in that the thermoplastic composition (a) comprises:

from 35 to 80% by weight of thermoplastic starch,

from 10 to 50% by weight of polyolefin,

15. Composition according to any one of the preceding claims, characterized in that the synthetic fibers (b) are chosen from glass fibers, carbon fibers, metal fibers and synthetic polymer fibers. melting temperature measured by DSC greater than 180 ° C and preferably greater than 200 ° C and / or HDT temperature greater than 70 ° C and preferably greater than 100 ° C, and more particularly be selected from short glass fibers long glass fibers, high tenacity carbon fibers, high modulus carbon fibers, low modulus aramid fibers, high modulus fibers, polyethylene terephthalate (PET) fibers, polybutylene terephthalate (PBT) fibers, polypropylene fibers (PP), polystyrene fibers (PS), polyamide fibers, polyurethane fibers, PLA fibers (in particular PLLA / PDLA stereocomplexes).

16. Composition according to any one of the preceding claims, characterized in that it comprises from 10% to 60% by weight, preferably from 20 to 50% and better still from 25 to 45% of synthetic fibers (b).

17. Composition according to any one of the preceding claims, characterized in that the synthetic fibers (b) have a diameter of between 2 and 35 microns, preferably between 5 and 30 microns, and more preferably between 8 and 15 microns.

18. Composition according to any one of the preceding claims, characterized in that the synthetic fibers (b) have a tensile modulus of rupture of between 60 and 450 GPa and preferably between 70 and 400 GPa.

19. Composition according to any one of the preceding claims, characterized in that it further comprises a binding agent chosen from compounds bearing at least two functions, free or masked, identical or different, chosen from isocyanate functions. , carbamoylcaprolactams, epoxides, aldehydes, halo, protonic acids, acid anhydrides, acyl halides, oxychlorides, trimetaphosphates, alkoxysilanes and mixtures thereof.

20. Composition according to any one of the preceding claims, characterized in that it further comprises aging-stabilizing agents, in particular UV-stabilizers, hydrophobing agents and antimicrobial agents.

21. Composition according to any one of the preceding claims, characterized in that it is non-biodegradable or non-compostable in the sense of standards EN 13432, ASTM D 6400 and ASTM D 6868.

22. Composition according to any one of the preceding claims, characterized in that it contains at least 25%, preferably at least 30%, and in particular more than 40% of material of renewable origin according to the method of determination of carbon of renewable origin ASTM D 6866, expressed with respect to all of said composition.

23. Process for the preparation of a composition based on plant material and synthetic fibers according to any one of the preceding claims, characterized in that it comprises the following steps:

24. The method of claim 23 characterized in that the mixing step (iii) is followed by a shaping treatment of the composition based on plant material (iv), at a temperature between 60 and 280 ° C, for example between 80 and 250 ° C, preferably between 120 and 200 ° C, and in particular between 160 and 185 ° C.

25. The method of claim 23 or 24 characterized in that the synthetic fibers selected in step (ii) comprise glass fibers and in that the mixing step (iii) is carried out by extrusion at a temperature of between 200 and 280 ° C, preferably between 220 and 270 ° C.