EP2550323A1

EP2550323A1 - Plant material compositions and method for preparing same

Info

Publication number: EP2550323A1
Application number: EP11715988A
Authority: EP
Inventors: Joël BERNAERTS; Laurie Coudyser; Léon Mentink; Didier Beaudoux; Bernard Constant
Original assignee: Roquette Freres SA
Current assignee: Roquette Freres SA
Priority date: 2010-03-25
Filing date: 2011-03-24
Publication date: 2013-01-30
Also published as: FR2957928B1; CN102918097A; US20130096236A1; FR2957928A1; WO2011117549A1

Abstract

The present invention relates to a novel thermoplastic composition, characterized in that it contains: a) 15% to 60% of at least one starchy material; b) 10% to 30% of at least one starchy material plasticizer; c) 15% to 70% of at least one polyolefin; and d) 10% to 40% of at least one plant material selected among plant fibers and plant fillers. The invention also relates to a thermoplastic composition preparation method that includes the following steps: (i) selecting at least one composition (a) containing at least one starchy material, one plasticizer of said starchy material, and one polyolefin; (ii) selecting at least one plant material (b) selected among plant fibers and plant fillers, said plant material being formed of particles, the dimensions of which are between 0.5 and 5000 micrometers; and (iii) mixing the composition (a) and the plant material (b) so as to obtain the thermoplastic composition according to the invention.

Description

PLANT BASED COMPOSITIONS AND PROCESS FOR PREPARING SUCH COMPOSITIONS

The present invention relates to novel thermoplastic compositions containing selected proportions of at least four components, namely, respectively, a starchy material, plasticizer of starchy material, polyolefin and plant material, said plant material being, further selected from vegetable fibers and vegetable fillers. It also relates to a process for preparing these thermoplastic 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, 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 "plant material" is intended to mean a product of vegetable origin, of essentially polysaccharide nature, cellulose, hemicellulosic, woody or amylaceous, of essentially proteinaceous nature or based on natural rubbers and in the form of particles or in the form of a fibrous material. In the context of the invention, said plant material is chosen from vegetable fibers and vegetable fillers as will be described later in the present application.

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. plan, the state of public opinion in search of sustainable development, more natural products, cleaner, healthier, recyclable and less expensive energy, 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 fossil origin.

In this spirit, different paths have been explored for several decades already, consisting in introducing bio-sourced materials as fillers in petro-plastic resins. These fillers have the double advantage of being weakly dense compared to mineral fillers and of being of natural origin and renewable in the short term. Among the petro-plastic resins, polyolefins have the advantages of being produced in very large volumes at relatively low prices, of presenting eco-profiles of interest to the environment, of being incinerable without the production of toxic gases unlike for example PVC and to be recyclable industrially.

Among plant materials, many studies have focused on the incorporation of up to 60% of plant fibers, especially flax and hemp fibers, cereal straw fibers, kenaf fibers and wood fibers. , cellulosic fibers (radius), in petro-plastic resins as in particular in polypropylene. This produces products commonly called 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 compounds. Indeed, the introduction of such fibers is not easy considering that the plant fibers are generally very hydrophilic while the resins are hydrophobic in nature. In fact, it is recommended to dry these fibers to reduce their hydrophobicity and to use synthetic products, generally of petroleum origin, as dispersing agents, compatibilizing agents and / or coupling agents, but also specific stabilizing agents. given the high instability of plant fibers in shear, heat, light and microorganisms. In addition, the maximum amounts of plant-based material that can be introduced into petro-plastic resins without compromising their properties remain relatively limited and usually remain in practice less than 50%.

Other types of plant materials have also been introduced as fillers into petro-plastic resins so as to correct the above-mentioned defects or to obtain advantageous properties.

This is the case of starch which has been introduced as a filler in a granular state, in particular in polyolefins. In this context, reference may be made, for example, to the patent application WO 2009 022195 which describes composites of polyolefins and granular starch. This starch is then a vegetable load having the advantage of being also renewable, but especially to be available in large quantities at an economically attractive price compared to oil and gas. A granular starch is a starch having a semicrystalline granule structure similar to that found for starch as naturally occurring in reserve organs and tissues of higher plants, particularly in cereal seeds, legume seeds, tubers of potato or cassava, roots, bulbs, stems and 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 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 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.

Such granular starches, that is to say in the structural state where they are in the reserve organs of plants, are insoluble in water. Before dispersion in the synthetic polymer constituting the matrix or continuous phase, it has been recommended to dry the native starch to a moisture content of less than 1% by weight, to reduce its hydrophilicity and thus facilitate its dispersion. For the same purpose, it has been recommended to coat it beforehand with fatty substances (fatty acids, silicones, siliconates) or to modify the surface of the starch grains by siloxanes or isocyanates or finally to associate with them synthetic dispersants of different chemical nature such as for example polyethylene glycols or ethylene-vinyl acetate copolymers (EVA). The composites thus obtained then generally contain at most 20% by weight of granular starch, since beyond this value, the mechanical properties of the composite materials obtained become too modified or too low compared to those of the polymers. Synthetics forming the matrix. The growth of such composites, sometimes called hybrid as well, has remained limited.

More recently, starch has been associated with polyolefins in a completely different state called "destructured" or "thermoplastic" and this according to a completely different technology. This destructured or thermoplastic state of the starch is obtained by plastification of granular starch by incorporation of a suitable plasticizer at a level generally comprised between 15 and 35% with respect 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 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 thermoplastic amorphous starches can be carried out in a low-hydrated medium by thermomechanical or extrusion processes. Obtaining a melted phase from granular starch requires not only a significant supply of mechanical energy and thermal energy but also the presence of a plasticizer at the risk, otherwise, to carbonize the starch.

The combination of thermoplastic starch and polyolefins makes it possible to obtain thermoplastic compositions whose properties can be modulated by the choices of the starch type, the nature of the plasticizer, the plasticization ratio, the incorporation rate of thermoplastic starch in polyolefins and the mixing process. The thermoplastic compositions thus obtained typically have a structure where the thermoplastic starch is present in island-dispersed form in a continuous polyolefin phase. This is explained by the fact that thermoplastic starches are very hydrophilic and are therefore very poorly miscible or compatible with polyolefins. Ordinarily, to improve the structure of these mixtures, there are added compatibilizing agents or coupling agents, such as, for example, copolymers with hydrophobic units and alternating hydrophilic units such as ethylene / acrylic acid (EAA) copolymers, polyolefins grafted with maleic anhydride or organosilane groups. Major advances have allowed in recent years to obtain new thermoplastic compositions having excellent mechanical properties in terms of stiffness, flexion and resilience to shocks, by the development of new processes such as those that were the subject of patent applications WO2009 / 095617, WO 2009/095618, WO 2009/095622 and WO 2010/010282 published in the name of the Applicant.

The present invention provides a novel and advantageous solution to the problems stated above by proposing novel thermoplastic compositions prepared from at least four components, at least one starchy material and at least one polyolefin, and having improved properties compared to to those of the prior art.

More specifically, the subject of the present invention is a thermoplastic composition, characterized in that it contains:

a) from 15 to 60% of at least one starchy material,

b) from 10 to 30% of at least one plasticizing agent of starchy material with a molar mass greater than 18 g / mol and less than 5000 g / mol,

c) from 15 to 65% of at least one polyolefin, and

d) from 10 to 40% of at least one plant material chosen from vegetable fibers and vegetable fillers,

said starch material a) being plasticized by the plasticizer b) and these percentages being expressed by dry weight relative to the dry weight of said composition.

Preferably, said composition contains:

a) from 15 to 50% of at least one starchy material,

b) from 10 to 25% of at least one plasticizing agent of starchy material,

c) from 25 to 50% of at least one polyolefin, and

d) from 15 to 40% of at least one vegetable material selected from fibers

plants and vegetable loads.

According to an advantageous variant, dependent on any one of the preceding variants, said composition is characterized in that it contains, in total, at least 27%, preferably 30 to 80%, and even more preferably 35 to 75%. %, of plasticized starch material consisting of a) and b), these percentages being expressed as total dry weight of starchy material (s) and plasticizer (s) of starch material relative to the dry weight of the thermoplastic composition.

According to a particularly advantageous variant, which is dependent on any one of the preceding variants, said composition is characterized in that it contains, in total, at least 52%, preferably 55% to 90%, of the plasticized starchy material constituted by at least one starchy material and at least one starchy material plasticizer (components a and b), and at least one polyolefin (component c), these percentages being expressed as total dry weight of starchy material, plasticizer (s) starch material and polyolefin (s) relative to the dry weight of the thermoplastic composition.

The Applicant has indeed found after many works that, surprisingly and unexpectedly, the use of the thermoplastic composition according to the invention, associating, moreover, in defined proportions, a plasticized starchy material, a polyolefin and a fiber or vegetable load allowed against all odds to obtain, compared to compositions of the prior art, including not containing fiber or vegetable filler or containing lesser or higher proportions, improved mechanical properties and even allowed to get rid or significantly reduce the amounts of compatibilizers or coupling agents ordinarily required to obtain satisfactory properties. Without wishing to be bound to any theory, the Applicant believes that the plasticized starchy material behaves itself, within the composition, in the manner of a compatibilizing or coupling agent between the selected plant material and the other constituents. of the composition, in particular the polyolefin.

The present invention also relates, in particular, to a thermoplastic composition according to the invention 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, injection or blowing. For the constitution of the composition according to the invention, it is possible to implement the various constituents in an indifferent order and according to very varied processes. It is possible, among other things, to prepare a thermoplastic intermediate composition that does not contain any fiber or vegetable filler and then, by any suitable means and in the appropriate proportions, mix said intermediate composition with the fibers and / or vegetable fillers.

The Applicant has also found that the thermoplastic composition according to the invention has, compared with compositions of the prior art, in particular containing a polyolefin but no plasticized starchy material, excellent properties in terms of interaction and adhering or adhering to fibers or vegetable fillers such as paper or cardboard, so that, alternatively, there is prepared an intermediate composition not yet containing vegetable fibers or fillers, an intermediate composition that the one can then use, among other things, as a means of bonding, between them, fibers and / or vegetable fillers.

The subject of the present invention is also a process for improving the bonding, between them, of fibers and / or vegetable fillers, characterized in that it comprises the following steps:

i. selecting at least one plant material chosen from vegetable fibers and vegetable fillers,

ii. selecting at least one composition containing a plasticized starchy material with a plasticizer of molar mass greater than 18 g / mol and less than 5000 g / mol and a polyolefin, and

iii. thermomechanical mixing of said plant material and said composition.

Step (iii) is carried out at a temperature advantageously between 80 and 200 ° C., preferably between 120 and 185 ° C. and even more preferably between 160 and 180 ° C. This step may in particular be done by hot pressing, thermomolding, extrusion, injection, and / or hot spraying of the intermediate composition on a mattress of plant material. We can prepare, in particular, panels or "fibrous mats" usable, for example, as acoustic and / or thermal insulation and may contain up to 95% or more of plant material.

The intermediate composition, free of fiber or vegetable filler, that can be used for the preparation of the thermoplastic composition according to the invention may especially be characterized in that it contains:

a) from 17 to 65% of at least one starchy material,

b) from 12 to 30% of at least one plasticizing agent of starchy material, and c) from 17 to 70% of at least one polyolefin,

these percentages being expressed by dry weight relative to the dry weight of said intermediate composition.

Preferably, said intermediate composition contains:

a) from 20 to 65% of at least one starchy material,

b) from 12 to 25% of at least one plasticizing agent of starchy material, and c) from 20 to 65% of at least one polyolefin.

According to an advantageous variant, said intermediate composition contains: a) from 25 to 60% of at least one starchy material,

b) from 15 to 25% of at least one plasticizing agent of starchy material, and c) c) from 25 to 60% of at least one polyolefin.

Said intermediate composition that can be used according to the invention may in particular have a density of between 0.95 and 1.3, preferably between 1.0 and 1.25, and more preferably between 1.05 and 1.15, according to the invention. to ISO 1,183.

The thermoplastic composition according to the invention or the intermediate composition that can be used for its preparation necessarily comprises a polyolefin. This polyolefin can be virgin that is to say having not had prior use although it can be formulated by addition of additives or by compounding. It can also be recycled, that is to say from polyolefin parts or objects recovered by recovery of material. In the present invention, the term "polyolefin" means a non-functionalized or ungrafted polyolefin or a mixture of such a polyolefin with a functionalized or grafted polyolefin. In the case where the polyolefin is a mixture of a non-functionalized and non-grafted polyolefin (POI) and of a functionalized and / or grafted polyolefin (PO 2), the ratio (POI) / (PO 2) can range from 1/99 at 99/1, advantageously from 10/90 to 90/10, for example from 25/75 to 75/25.

The polyolefin may be obtained from monomers of fossil origin and / or monomers derived from renewable natural resources, as it may be from a deposit of recycled material or to be recycled.

As examples of non-functionalized or ungrafted polyolefins that may be used in the context of the present invention, mention may be made in particular of:

a) homopolymers of olefins, such as, for example, linear or radical low density polyethylenes (LDPE), high density polyethylenes (HDPE), polypropylenes (PP) of isotactic, syndiotactic or atactic form, polybutenes and polyisobutylenes,

(b) copolymers based on at least two olefins, such as, for example, ethylene - propylene (P / E) copolymers, ethylene - butene copolymers and ethylene - octene copolymers,

c) any mixtures of at least two of the aforesaid products.

As examples of functionalized or grafted polyolefins that may be used in the context of the present invention, mixed with unfunctionalized or ungrafted polyolefins, mention may be made in particular of:

a) homopolymers of functionalized or grafted olefins, for example with acids or anhydrides such as maleic, acrylic and methacrylic acids (or anhydrides), such as, for example, maleic anhydride grafted polyethylenes and polypropylenes, with oxiranes such as that methacrylate or glycidyl acrylate, or by silanes,

(b) copolymers based on at least two olefins, for example ethylene - propylene (P / E) copolymers, ethylene - butene copolymers and functionalized or grafted ethylene - octene copolymers, example with acids or anhydrides, such as maleic, acrylic and methacrylic acids (or anhydrides), such as, for example, maleic anhydride grafted polyethylenes and polypropylenes, with oxiranes, such as methacrylate or glycidyl acrylate, or by silanes,

c) any mixtures of at least two of the aforesaid products.

The polyolefin can be further synthesized from monomers derived from renewable natural resources in the short term such as plants, microorganisms or gases. It may especially be polyolefin obtained from bio-sourced monomers, in particular from glycerol, bio-ethanol, bio-methanol or bio-propanediol.

Preferably, the polyolefin is chosen from polyolefins obtained from bio-sourced monomers, and mixtures thereof.

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

The polyolefin is conventionally a non-biodegradable or non-compostable resin in the sense of the standards EN 13432, ASTM D 6400 and ASTM D 6868.

According to another preferred variant, the polyolefin is a polyolefin containing at least 15%, preferably at least 30%, in particular at least 50%, better still at least 70% or even more than 80% (including 100%), carbon of renewable origin according to ASTM D 6852 and / or ASTM D 6866, with respect to all the carbon present in said polyolefin.

This polyolefin is preferably chosen from non-functionalized or ungrafted polyolefins, mentioned above (homopolymers of olefins, copolymers based on at least two olefins and any mixtures thereof) such as linear or radical low density polyethylenes (LDPEs), high density polyethylenes (HDPE), polypropylenes (PP) of isotactic, syndiotactic or atactic form, polybutenes, polyisobutylenes, ethylene - propylene (P / E) copolymers, ethylene - butene copolymers and copolymers of ethylene-octene, as well as any mixtures thereof. The polyolefin may also be a mixture of polyolefins, at least one of which may be functionalized or grafted, in particular carrying silane, acrylic or maleic anhydride units.

The thermoplastic composition according to the invention or the intermediate composition that can be used for its preparation also necessarily comprises at least one plasticized starchy material. It may be in particular a plasticized starch, the latter preferably having 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 essentially 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 plasticized 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 starchy material used for the preparation of the composition according to the invention or the intermediate composition that can be used according to the invention is preferably chosen from granular starches, water-soluble starches and organomodified starches.

According to a first variant, it is a granular starch. The crystallinity of said granular starch can be reduced to less than 15% by thermomechanical treatment 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 starting, 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 demineralized water, less than 5% by weight and can be practically insoluble in cold water.

According to a second variant, the starch is a water-soluble starch which may also come from all botanical origins, including a starch which is water-soluble, rich in amylose or, conversely, rich in amylopectin (vaxy). 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 starchy solution, by precipitation with a non-solvent or by cooking. hydrothermal, by chemical or other functionalization. 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 more preferably between 0.5 and 12. Such maltodextrins are for example manufactured and marketed by the Applicant. under the tradename 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 almost zero ordinary . The functionalized starches can be obtained from a native or modified starch. The high functionalization can 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 modification or functionalization of 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 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.

Within the meaning of the invention, the term "organomodified starch" is intended to mean 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, isosorbide dioleate 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.

Organomodified starch can be prepared by high functionalization of 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 highly functionalized organomodified starches, preferably organosoluble, may be particularly starch acetates, 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, in the context of the invention, the amylaceous material is chosen from native starches, pregelatinized starches, extruded starches, atomized starches, fluidized starches, oxidized starches, cationic starches, anionic starches, hydroxyalkylated starches, crosslinked starches, starch acetates, fatty starch and fatty chain esters of 4 to 22 carbons, dextrins, maltodextrins and any mixtures of these products. Most preferably, the starchy material used in component a is a native starch.

Furthermore, the thermoplastic composition according to the invention or the intermediate composition that can be used according to the invention comprises a plasticizing agent of starchy material.

The term "plasticizing agent" is intended to mean any organic molecule of low molecular weight, that is to say having a molecular mass of less than 5000 and greater than 18 g / mol which, when incorporated by a thermomechanical treatment into a temperature between 20 and 200 ° C to the thermoplastic composition according to the invention, to the intermediate composition used according to the invention or to the single starchy material results in a decrease in the glass transition temperature of said composition or material and / or results in reducing the crystallinity of the starchy material until it reaches a substantially amorphous state. Water is the most natural plasticizer of the starchy material, especially starch, and is therefore commonly used.

The plasticizer used in the context of the present invention is preferably chosen from diols, triols and polyols such as glycerol, polyglycerol, isosorbide, sorbitans, sorbitol, mannitol, sugars, such as glucose, maltose, fructose or sucrose or hydrogenated glucose syrups, 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 at most 380.

It may, when the starchy material consists of an organomodified starch, be very particularly 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 or ester esters. fatty acids of mono-alcohols, diols, triols or polyols such as ethanol, diethylene glycol, glycerol and sorbitol. By way of example, mention may be made of glycerol diacetate (diacetin), glycerol triacetate (triacetin), isosorbide diacetate, isosorbide dioctanoate, isosorbide dioleate, isosorbide dilaurate, esters of dicarboxylic acids or dibasic esters (DBE of English dibasic esters) and mixtures of these products.

According to an advantageous variant, the plasticizer is contained in the plasticized starchy material in a proportion of 25 to 110 parts by dry weight, preferably in the proportion of 30 to 100 parts by dry weight and in particular at the rate of 30 to 90 parts by dry weight. per 100 parts by dry weight of starchy material, for example starch.

The thermoplastic composition according to the invention or the intermediate composition that can be used according to the invention preferably comprises, as plasticized starchy material, 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 chains fatty acids of 4 to 22 carbons, dextrins, maltodextrins and mixtures any of these products, plasticized by thermomechanical mixing with at least one of the plasticizers listed above.

The composition according to the invention may also comprise a binding agent.

The term "binding 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 functional groups such as starchy material, for example starch, or the plasticizer of the starchy material. This binding agent may be added to the composition in order to allow covalent attachment of at least a portion of the plasticizer to the starch, or even to the polyolefin, in particular if it carries functional groups. .

This binding agent may then be chosen for example from compounds carrying at least two functions, free or masked, identical or different, in particular chosen from isocyanate, carbamoylcaprolactam, aldehyde, epoxide, halogen, protonic acid, anhydride and other functional groups. acid, acyl halide, oxychloride, trimetaphosphate, alkoxysilane and combinations thereof.

It can advantageously be chosen from the following compounds:

As binding agents that can be used in the present invention, mention may be made of:

diisocyanates, preferably methylenediphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (H12MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), hexamethylene -diisocyanate (HMDI) or lysine diisocyanate (LDI), the aliphatic diisocyanate of molar mass 600 g / mol obtained from dimer of fatty diacid (DDI® 1410 Diisocyanate)

dimers, trimers and tetramers of diisocyanates,

triisocyanates, tetraisocyanates and the homopolymers of the existing di, tri- and tetraisocyanates,

the so-called "isocyanate-free" prepolymers resulting from a reaction of a diol or an amine on a diisocyanate under conditions such that the prepolymer contains an isocyanate function at each of its ends (α, ω-functional or telechelic polymer) without the free diisocyanate being detectable, the isocyanate prepolymers of the dendrimer type, prepared from compounds having several alcohol or amino functional groups and polyisocyanates prepared so that the dendrimer formed has only reactive isocyanate functions at the end of the branch, the dendrimer containing or not free di or triisocyanates,

dialkylcarbonates, especially dianhydrohexitol dialkylcarbonates, and in particular isosorbide dialkylcarbonates,

dicarbamoylcaprolactams, preferably 1,1 -carbonyl-bis-caprolactam, diepoxides,

compounds having an epoxide function and a halide function, preferably epichlorohydrin,

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

polyacids and polyanhydrides, preferably mellitic acid or its derivatives, such as trimellitic acid or pyromellitic acid,

oxychlorides, preferably phosphorus oxychloride,

trimetaphosphates, preferably sodium trimetaphosphate,

alkoxysilanes, preferably tetraethoxysilane,

heterocyclic compounds, preferably bis-oxazolines, bis-oxazolin-5-ones and bis-azalactones,

methylenic or ethylenic diester derivatives, preferably methyl or ethyl carbonate derivatives,

any mixtures of any two or more of the aforesaid goods.

Particularly preferably, a diisocyanate, and in particular methylene diphenyl diisocyanate (MDI), is used as the linking agent. Moreover, the use of isophorone diisocyanate (IPDI) or dicyclohexylmethane diisocyanate (H12MDI) makes it possible to obtain final compositions that are particularly poorly colored. Any mixture of at least two of the above three diisocyanates (MDI, IPDI, H12MDI) can be used.

The amount of binding agent, expressed as dry weight and relative to the sum, expressed as dry weight of the composition according to the invention may advantageously be 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 incorporation of the binding agent into the mixture of the composition according to the invention or, preferably, into the intermediate composition that can be used according to the invention can be done by physical mixing at low temperature or cold, but preferably by mixing. when heated to a temperature above the glass transition temperature of the starchy material. This mixing temperature is advantageously between 60 and 200 ° C. and better still between 100 and 160 ° 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 or the intermediate composition that can be used for its preparation may advantageously also comprise an agent that improves its impact resilience, especially at a temperature of 23 ° C. or below, as well as at -18 ° C. It may be in particular an ethylene-propylene, ethylene-styrene or styrene-butadiene copolymer-type polymer, an elastomeric material of natural rubber type, styrene-butylene-styrene copolymer (SBS) or styrene-ethylene copolymer. -butylene styrenes (SEBS). This resilience-improving agent may represent from 1 to 15%, preferably from 2 to 12% and better still from 5 to 10% by weight (dry / dry) of the composition according to the invention.

The thermoplastic composition according to the invention or the intermediate composition that can be used for its preparation advantageously has the following preferred variants, taken separately or in combination, including with the variants described above: it contains, in total, at least 51%, preferably at least 70%, in particular more than 80%, of biobased carbon-based materials of renewable origin within the meaning of ASTM D 6852 and / or the standard ASTM D 6866, expressed as dry weight relative to the dry weight of said composition,

- it is non-biodegradable or non-compostable within the meaning of EN 13432, ASTM D 6400 and ASTM D 6868,

it has a maximum bending stress (according to ISO 178) greater than 10 MPa, preferably greater than 20 MPa, and / or

it has a maximum tensile stress (according to ISO 527) greater than 10 MPa, preferably greater than 15 MPa.

Moreover, the composition according to the invention has particularly advantageous mechanical characteristics.

It can especially be characterized in that it presents:

a maximum bending stress (ISO 178) greater than 30 MPa, and / or

- a maximum tensile stress (ISO 527) greater than 20 MPa.

The present invention makes it possible in particular to obtain a new thermoplastic composition based on starchy material, plasticizer of starchy material, polyolefin and fiber or vegetable filler, characterized in a remarkable manner in that it simultaneously has:

a maximum flexural stress greater than 30 MPa, in particular greater than 35 MPa, and

a maximum tensile stress greater than 50 MPa, especially greater than 55 MPa.

It can also be characterized in that it has a flexural modulus (ISO 178) and / or a tensile modulus (ISO 527) greater than 1000 MPa, especially greater than 1500 MPa.

It may advantageously be characterized in that it has a flexural modulus (ISO 178) and a traction module (ISO 527) greater than 1500 MPa, in particular greater than 2000 MPa. The plant material constituting the fourth essential component of the thermoplastic composition according to the invention is, as mentioned above, selected not only by its rate of introduction into said composition, but also by its nature, namely chosen from vegetable fibers. and vegetable loads. It is 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, its color. or its smell.

The plant material thus selected in the form of fibers and / or vegetable fillers consists of particles whose largest dimension is generally between 0.5 and 5000 microns and preferably between 0.5 and 1000 microns. Advantageously, it may consist of a mixture of small particles whose largest dimension is between 0.5 and 300, preferably between 100 and 275 micrometers and large particles whose largest dimension is between 350 and 5000, preferably between 400 and 3000 micrometers. The weight ratios of the small particles / coarse particles generally vary from 0.1 to 9 and preferably from 0.5 to 2. Thus, it is possible to better adjust the thermomechanical characteristics and the organoleptic characteristics of the thermoplastic composition according to the invention.

By convention, in the context of the present invention and with respect to plant fibers and fillers, the term "dimension" is the largest dimension of the particles of said fibers or fillers, these being able to present in very different aspects (granules , powders, fibers, chips ...), their largest dimension can be considered, on a case by case basis, being their diameter, their length or any other dimension easily and commonly measurable by those skilled in the art.

Furthermore, the filler or vegetable fiber thus selected according to the invention most often has a water content of between 0.5 and 30%, preferably between 1 and 20%, more preferably between 1 and 15%. This water content may advantageously be between 2 and 15%. The vegetable load may in particular be chosen from granular starches, native or modified, as defined above, and unplasticized. As a result, this starch placed under polarized light always has in microscopy a "Maltese cross" typical of the crystalline granular state. The starch selected as plant material, can come from all botanical origins, including a starch rich in amylose or conversely rich in amylopectin (waxy). Preferably, this granular starch is pea starch, wheat starch, waxy rice starch or waxy corn starch. It has been shown that these preferred granular starches are advantageous in terms of whiteness and appearance of the compositions according to the invention. It may especially be a waxy corn starch.

When the vegetable filler is selected from granular starches, their dimensions are generally between 0.5 and 100 microns, especially between 1 and 70 microns. Advantageously, these dimensions are between 2 and 50 microns, preferably between 4 and 45 microns, and more preferably between 5 and 40 microns. These dimensions may especially be between 8 and 35 microns, especially between 10 and 30 microns.

The vegetable filler may also be chosen from non-fibrous co-products of starch, mill, candy, paper mill or oil mill. It may be in particular gums of wheat or triticale, oil cake or maize, guar or carob meal, cereal protein or tubers allowing in particular to obtain beige to brown hues, rosins or terpene resins for example to improve the adhesion properties.

The vegetable load can also be chosen from algae and algae extracts. It may be in particular dried and ground whole algae or extracts of algae such as polysaccharides such as alginates and carrageenans.

The vegetable fiber may, for its part, be chosen also from cellulosic or lignocellulosic fibers and in particular from the fibrous co-products of starch, mill, candy, paper mill or oil mill. It can then be elementary fibers, in individualized form, in a cluster or in agglomerates. These may include cereal bran, corn kernels, wheat or triticale fiber, rice husks, sunflower shells, outer seed shells, beet pulp or potato pulp, bagasse of sugar cane, walnut hulls, hazelnuts or almonds. It may be in particular wood in the form of sawdust, in particular beech, oak, birch, eucalyptus, pine or fir. It can also be spruce wood. It may also be fibrous cellulosic clusters consisting of fibrils with a diameter of 10 to 100 nanometers for a length of a few micrometers to a few centimeters, such as paper or cardboard. It may also be lignocellulosic fibers such as wood, flax, hemp, bamboo, sisal, miscanthus, banana, pea, potato, cereals, palm, cocoon, jute, straw, cotton, kenaf or others. For example, products that can advantageously be used among these fibers include sisal, bamboo, coconut or jute fibers.

Potable fibers or fillers that can potentially be used according to the invention are described in particular in patent applications WO 94/03543, CA 2,217,541 and EP 1,265,957.

The plant material used according to the invention may of course be any mixture of at least two of the fibers and / or vegetable fillers mentioned above.

Preferably, during its use, that is to say during its incorporation to form the composition according to the invention, it has a water content corresponding to its equilibrium humidity in an atmosphere at 66% moisture content. relative and a temperature of 20 ° C.

It may be chosen advantageously to increase the nucleation or the crystallization ability of the polyolefin present in the thermoplastic composition (a) and thus to adjust the mechanical properties and shrinkage properties of the composition according to the invention.

According to an advantageous variant, the plant material consists of particles whose size is between 0.5 and 5000 micrometers, and is chosen from: granular starches, native or modified,

co-products of starch, mill, candy, paper mill or oil mill,

cellulosic or lignocellulosic fibers,

- algae and algae extracts, and

any mixtures of at least two of these products.

Preferably, the plant material is chosen from cellulosic or lignocellulosic fibers such as wood, sisal, bamboo, coconut or jute fibers.

The thermoplastic composition according to the invention has the advantage of being relatively sparse and of having a density measured according to the ISO 1183 method of between 1.05 and 1.25 and preferably between 1.1 and 1.2.

Furthermore, the composition according to the invention or the intermediate composition that can be used for its preparation may comprise other polymers, of any kind, in a small amount, for the adjustment of its characteristics. However, it will preferably comprise polymers or copolymers other than polyolefins, partially or totally bio-sourced, such as in particular polyurethanes (PU), thermoplastic polyurethanes (TPU), polyamides, polylactates (PLA), polybutylenes succinates (PB S, PB SA), polyhydroxyalkanoates (PHA, PHB, PHBV) or any mixtures thereof.

Fillers and other additives of all types, including those detailed below, may also be incorporated in the composition of the present invention or the intermediate composition used for its preparation.

It may be products designed 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 or adjusting agent for the mechanical or thermal properties chosen from among minerals, salts and substances organic. 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, kevlar.

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 .

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

odorant properties (perfumes or odor masking agents), optical properties (brighteners, whiteners such as titanium dioxide, dyes, pigments, dye enhancers, opacifiers, dulling agents such as 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 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 / alcohol copolymers vinyl, fatty amines, lubricating agents, 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.

With a view to the preparation of the composition according to the invention, it is possible to use a number of methods that provide, in particular, extremely varied moments and orders of introduction of the components of said composition (polyolefin, amylaceous material, plasticizer of starchy material, fiber or vegetable filler). , optional bonding agent, impact resilience enhancer, any other additives).

Thus, the fiber and / or vegetable filler can be introduced after all or part of it has been previously dispersed in a composition already containing the starchy material, its plasticizer and the polyolefin. In addition, in the final composition, said fiber and / or vegetable filler, regardless of how and when it was incorporated, may be dispersed mainly in the plasticized starch material, or in the polyolefin phase, or even be divided between these two phases.

Among all these possibilities of implementing said components, the present invention particularly relates to a process for preparing a thermoplastic composition according to the invention 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 starchy material, a plasticizer of said starchy material having a molar mass greater than 18 g / mol and less than 5000 g / mol and a polyolefin, a plasticization of the material starch being produced by thermomechanical mixing with said plasticizer, (ii) selecting at least one plant material (b) chosen from vegetable fibers and vegetable fillers, consisting of particles whose size is between 0.5 and 5000 micrometers, preferably chosen from:

granular starches, native or modified,

- co-products of starch manufacture, milling, candy, paper mill or oil mill,

cellulosic or lignocellulosic fibers,

- algae and algae extracts,

and any mixtures of at least two of these products, and

(iii) thermomechanical mixture, composition (a) and plant material (b) so as to obtain the thermoplastic composition according to the invention.

Said composition (a) may in particular correspond to the "intermediate composition" as previously described in all its variants.

The incorporation of the plasticizer can be performed cold prior to its thermomechanical mixing with the starchy material. The thermomechanical mixture made to plasticize the starchy material is carried out under heat at a temperature of preferably between 60 and 200 ° C., more preferably between 80 and 185 ° C. and in particular between 100 and 160 ° C., in a discontinuous manner. for example by kneading / kneading, or continuously, for example by extrusion. The duration of this mixture can range from a few seconds to a few hours, depending on the mixing mode selected.

Furthermore, the incorporation of the plant material (b) (step (iii)) can be done by physical mixing at low temperature or cold in the composition (a) but preferably by hot mixing at a temperature above the highest glass transition temperature of the composition (a). This mixing temperature is advantageously between 80 and 200 ° C., preferably between 120 and 185 ° C. and even more preferably between 160 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. This gives a thermoplastic composition, very homogeneous as can be observed by observation under a microscope. Of course, when the introduced vegetable filler is starch, step (iii) is carried out in such a way that this starch remains in the state of charge and is not plasticized, that is to say in using a sufficiently short mixing time not to laminate the granular starch.

Preferably, during its use, that is to say during its incorporation to form the composition according to the invention, the selected plant material has a water content corresponding to its equilibrium humidity in a 66% atmosphere. relative humidity and a temperature of 20 ° C. This water content is usually between 5 and 20% and generally between 8 and 15%.

Preferably, the process according to the invention is characterized in that the mixing step (iii) is followed by a shaping treatment of the thermoplastic composition according to the invention (iv) at a temperature of between 80.degree. and 200 ° C, preferably between 120 and 185 ° C, and in particular between 160 and 180 ° C.

In the context of its research, the Applicant has found that, contrary to all expectations, the introduction of vegetable matter (b) makes it possible to considerably reduce the sensitivity to water, to water vapor and to the heat of the composition. obtained in comparison with products prepared without the addition of vegetable matter. This opens the way to new applications for the compositions of the invention which also have the advantage of being very highly constituted of renewable raw materials and of being able to present thermoplastic properties suitable for shaping according to the processes in place. in the plastics industry or the wood industry, of satisfactory physicochemical stability under the conditions of implementation, of sufficient stability to aging especially with respect to oxygen, carbon dioxide, UV, fatty substances , flavors, essences and fuels, and recyclability.

The subject of the present invention is also the use of a composition comprising at least one starchy material plasticized by a plasticizer of molar mass greater than 18 g / mol and less than 5000 g / mol as compatibilizing agent between a plant material (b) and a polyolefin. It also relates to a process for improving the compatibility between a plant material and a polyolefin, characterized in that it comprises the following steps:

i. selecting at least one plant material selected from vegetable fibers and vegetable fillers and at least one polyolefin,

ii. selecting at least one plasticized starchy material by a plasticizer with a molar mass greater than 18 g / mol and less than 5000 g / mol, and

iii. mixing, preferably thermomechanical mixing, the plant material and the polyolefin in the presence of said starchy material so as to improve the plant material / polyolefin compatibility within the resulting thermoplastic composition.

Step (iii) is carried out at a temperature advantageously between 80 and 200 ° C., preferably between 120 and 185 ° C. and even more preferably between 160 and 180 ° C.

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 51%, preferably at least 55%, and in particular more than 60% of biobased materials based on carbon of renewable origin (ASTM D 6852 and / or ASTM D 6866), expressed as dry weight relative to the dry weight of said composition. This carbon of renewable origin is that constitutive of the starch necessarily present in the composition according to the invention and that constitutive of the plant material (b) also necessarily present, but can also be that of the polyolefin which is preferably bio-sourced, that of the other possible constituents of the composition 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 conceivable to use the compositions according to the invention, as bioplastic materials or composite materials, useful for preparation by injection, extrusion, blowing, calendering, molding, thermoforming, compacting, spinning, kinking or other techniques, objects, parts, bottles, jars, containers, tanks, sheets, panels, bars, cleats, beam profiles, tables, interior furniture, street furniture, mats, nonwovens, door trim, wall, insulation, auto parts, electrical parts, wiring, ducts, dashboards, hoods or other household sports and leisure articles, household appliances, tools or useful for different industries such as the building industry, packaging, electricity, transportation and equipment.

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. It 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, able to be shaped or used in the wood processing industry such as a wood panel or wood / polymer composites.

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

EXAMPLE 1 Compositions, whether or not conforming to the invention, based on sisal

Preparation of compositions

For this example, the thermoplastic composition (a) is a composition comprising, on a dry weight basis:

on the one hand, 52% of a thermoplastic starch obtained from: native starch marketed by the Applicant under the name "SP wheat starch" with a water content of about 12%,

an aqueous plasticizing composition of polyols based on glycerol and sorbitol, marketed by the Applicant under the name POLYSORB® G 84/41/00 having a water content of about 16%,

and P / o of methylenediphenyl diisocyanate (MDI),

and on the other hand, 48% of a polyolefin consisting of a mixture of a commercially ungrafted polypropylene and a commercially grafted polypropylene.

This composition (a), thermoplastic, is obtained according to the method according to the patent application WO 2010/010282 published in the name of the Applicant and this, using a TSA twin-screw extruder, having a diameter (D) 26 mm and length of 50 D, so as to obtain a total material flow rate of 15 kg / h, and retaining the following extrusion conditions:

Temperature profile (ten heating zones Z1 to Z10): 200/120/140/140/160/170/160/150/160/160,

- Screw speed: 200 rpm.

The constituents of the thermoplastic composition (a) are introduced into the extruder as follows:

the polyolefin, in the main hopper of the extruder, following which it passes through all of the ten heating zones Z1 to Z10 of the extruder,

the plasticizer of the starchy component (POLYSORB®) at zone Z2, the plasticizer / wheat starch ratio being set at 67 parts / 100 parts,

the starchy component (unplasticized wheat starch) at zone Z3

- and the liaison agent at zone Z7.

A water extraction is operated by slight depression at the Z6 zone.

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. This thermoplastic composition (a) is referred to as "Resin A" and is used as "intermediate composition" by combining it, in order to obtain a composition according to the invention, with a plant material (b) consisting of sisal fibers whose main dimension (length) is of the order of 500 micrometers. 25% by weight of sisal fibers containing about 8.5% water, based on the total weight of the composition according to the invention, are mixed with Resin A.

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

- Temperature profile (4 heating zones): increasing profile from 165 ° C to

175 ° C

- Cutting temperature at the top: 200 ° C

- Degassing of the water of the material before the exit of the extruder

- Speed screw: 350 rpm

- Flow rate: 350 kg / h.

At the extruder outlet, the rods are cooled under water at 20 ° C and then dried at 80 ° C under vacuum for 4 hours. The density of the composition according to the invention thus obtained is close to 1.13. It contains about 23.4% vegetable fibers, this percentage being expressed by dry weight relative to the dry weight of the thermoplastic composition according to the invention.

Identical preparation of a control composition 2 was prepared using instead of Resin A, a mixture (control composition 1) comprising 97% MFI (Melt Flow Index) co-polymer PPC16N polypropylene of 16 (230). ° C, 2.16 kg) having mechanical characteristics very close to those of Resin A and 3% of 1% maleic anhydride grafted polypropylene as compatibilizer. Only extrusion conditions on a 6mm die are slightly modified in the sense that:

the profile is increasing from 190 ° C. to 210 ° C.,

- and the temperature in cross section at the head is fixed at: 220 ° C. Mechanical characteristics of the compositions according to the invention or not:

It is observed that the composition according to the invention has much better mechanical characteristics than the control composition 2 and this, for all the criteria measured. The plasticized starch present in Resin A appears to act both on improving adhesion to sisal fibers and improving polypropylene compatibility.

The composition according to the invention may also be obtained by the same method as that applied usually and advantageously without modification of the tooling and by working at temperatures below 20 ° to 35 ° C. below the control composition 2. significant energy savings and reduce the need for resources of fossil origin but also less degradation of the reinforcing properties conferred by the plant fibers with respect to the polymer matrix. In addition, the composition according to the invention, unlike the control composition 2, has a beautiful natural appearance and great homogeneity. It also has a pleasant feel explained by the presence of starch used in the thermoplastic composition (a).

It is found that the composition according to the invention comprising a total of about 64% of bio-sourced material has many technical advantages compared to the control composition 2 which however comprises only 23.4% of renewable natural origin material.

EXAMPLE 2 Compositions, whether or not conforming to the invention, based on wood powders

A) The procedure given in EXAMPLE 1 is repeated, using instead of sisal fibers in combination with Resin A (composition according to the invention) or with PPC16N (control composition):

About 17.6%, relative to the final composition (dry / dry), of a sawdust comprising particles of size between 0.5 and 3 millimeters, and

About 17.6%, relative to the final composition (dry / dry) of a wood flour, comprising particles of size close to 250 micrometers.

This sawdust and this wood flour have, respectively, at the time of their introduction into Resin A or PPC16N, a water content of approximately 11.5% and 12.4%.

The results of the mechanical tests obtained are as follows:

It is found that the composition according to the invention, which comprises in total about 69% of bio-sourced material, has much better mechanical properties than the control composition which however comprises only about 35% of renewable natural origin material.

B) For this example, various intermediate thermoplastic compositions are selected for producing compositions according to the invention and comparative.

The first intermediate composition comprises, in dry weight:

on the one hand, 52% of a thermoplastic starch obtained from:

native starch marketed by the Applicant under the name "SP wheat starch" with a water content of about 12%,

and P / o of methylenediphenyl diisocyanate (MDI),

and on the other hand, 48% of a polyolefin consisting of a mixture in equal proportions of a commercially ungrafted polypropylene and a commercially grafted polypropylene. The second intermediate composition is identical to the first composition, with the difference that the thermoplastic starch does not comprise MDI.

The third intermediate composition consists of a mixture of a non-grafted polypropylene and a grafted polypropylene used for the manufacture of the first two intermediate compositions.

These intermediate compositions are obtained according to the method of the example

1.

Compositions A (according to the invention), B (according to the invention) and C (comparative) are obtained by mixing the first, second and third intermediate compositions respectively with:

About 17.6%, relative to the final composition (dry / dry), of a sawdust comprising particles of size between 1 and 2 millimeters, and about 17.6%, relative to the final composition ( dry / dry), a wood flour, comprising particles of size close to 220 micrometers.

The results of the mechanical tests obtained are as follows:

It is observed that the introduction of vegetable fillers into the compositions comprising the plasticized starch (with or without MDI) makes it possible to improve the tensile modulus much more (module six times larger) than when the composition does not not understand (module three times larger only). In this composition comprising vegetable fillers, the introduction of MDI allows a slight increase in tensile and impact properties.

Example 3 Compositions, Containing or Not According to the Invention, Based on Native Waxy Corn Starch

Preparation of compositions

For this example, the resin A as described above is chosen as the thermoplastic composition (a) or intermediate composition that can be used according to the invention. A composition according to the invention is prepared by using as plant material (b), in this case as vegetable filler, a waxy maize native starch marketed by the Applicant.

40% by commercial weight of said waxy native starch is mixed with Resin A at approximately 12% water, relative to the total dry weight of the composition according to the invention.

The conditions of preparation by extrusion die 3 cm in diameter, are as follows:

- Temperature profile (20/80/180/180/180/180/180180) for 8 heating zones)

- Cutting temperature at the top: 180 ° C

- Degassing of the water of the material before the exit of the extruder

- Speed screw: 200tr / min

- Flow rate: 5kg / h.

The thermoplastic composition according to the invention thus obtained contains approximately 35% by weight of vegetable filler, this percentage being expressed by dry weight relative to the dry weight of the thermoplastic composition according to the invention.

A control composition is prepared in the same manner using, in place of Resin A, an MFI polypropylene polypropylene HP456J of MFI 16 (230 ° C., 2.16 kg) having mechanical properties superior to those of the resin. A in terms of modulus of resistance and stiffness. To this polypropylene is added 4% of maleic anhydride grafted polypropylene as compatibilizer between the polypropylene and the hydrophilic fillers.

Mechanical characteristics of the compositions according to the invention or not: Flexural modulus

(MPa) Max (MPa)

ISO 178 ISO 527

Resin A (thermoplastic composition (a)) 580 17

Resin A and

35% native starch corn waxy 1688 22

(composition according to the invention)

PP Moplen HP456J

1522 35

(PP witness only)

PP Moplen HP456J and 35% native corn starch

waxy + 4% compatibilizing agent 2134 34

(control composition)

It is observed that the reinforcing effect of the waxy corn starch load on flexural modulus (stiffness) and resistance (maximum stress) properties is much higher for Resin A than for the polypropylene base, which also has compatibilizing agent.

In fact, while the modulus is three times higher for resin A compounded compared to virgin resin A, the polypropylene modulus is only increased by a factor of 1.4.

In addition, no effect is visible on the maximum stress for polypropylene while the composition according to the invention makes it possible to increase the resistance (maximum stress) by 5 MPa.

The fact of compounding Resin A, an intermediate composition that can be used according to the process of the invention, therefore has a very advantageous gain on the effectiveness of the increase in mechanical properties compared with the polypropylene base control compositions, while enabling it to be freed of the use of grafted polypropylene as a compatibilizer. The plasticized starch present in Resin A appears to act both on improving the adhesion of starch fillers and on improving polypropylene compatibility.

It is further noted that the composition according to the invention, which comprises in total about 71% of bio-sourced material, has modulus properties of rigidity relatively close to the control composition which however comprises only about 35% of material of renewable natural origin.

Claims

1. Thermoplastic composition, characterized in that it contains:

a) from 15 to 60% of at least one starchy material,

c) from 15 to 65% of at least one polyolefin, and

2. Composition according to claim 1, characterized in that it contains:

a) from 15 to 50% of at least one starchy material,

b) from 10 to 25% of at least one plasticizing agent of starchy material, c) from 25 to 50% of at least one polyolefin, and

d) from 15 to 40% of at least one plant material chosen from vegetable fibers and vegetable fillers.

3. Composition according to one of claims 1 or 2, characterized in that it contains, in total, at least 27%, preferably from 30 to 80%, and even more preferably from 35 to 75%, from at least one starchy material and at least one plasticizer of starchy material, these percentages being expressed as total dry weight of starchy material (s) and plasticizer (s) of starchy material relative to the dry weight of the thermoplastic composition.

4. Composition according to any one of claims 1 to 3, characterized in that it contains, in total, at least 52%, preferably 55 to 90%, of at least one starchy material, at least a plasticizer of starchy material and at least one polyolefin, these percentages being expressed as total dry weight of starchy material (s), plasticizer (s) of starchy material and polyolefin (s) relative to the dry weight of the thermoplastic composition.

5. Composition according to any one of claims 1 to 4, characterized in that the polyolefin is chosen from:

a) homopolymers of olefins, in particular linear or radical low density polyethylenes (LDPE), high density polyethylenes (HDPE), polypropylenes (PP) of isotactic, syndiotactic or atactic form, polybutenes and polyisobutylenes,

(b) copolymers based on at least two olefins, in particular ethylene - propylene (P / E) copolymers, ethylene - butene copolymers and ethylene - octene copolymers,

(c) homopolymers of olefins functionalized or grafted with: (i) acids or anhydrides, in particular maleic, acrylic and methacrylic acids (or anhydrides), in particular maleic anhydride grafted polyethylenes and polypropylenes, (ii) oxiranes, in particular methacrylate or glycidyl acrylate, or iii) with silanes.

(d) copolymers based on at least two olefins, in particular ethylene - propylene (P / E) copolymers, ethylene - butene copolymers and ethylene - octene copolymers, functionalized or grafted, in particular by means of acids, anhydrides, oxiranes or silanes,

e) any mixtures of at least two of the aforesaid products.

6. Composition according to any one of claims 1 to 5, characterized in that the plant material consists of particles whose size is between 0.5 and 5000 micrometers, and is chosen from:

granular starches, native or modified,

- by-products of starch manufacture, milling, candy, paper mill or oil mill, - cellulosic or lignocellulosic fibers, - algae and algae extracts, and

any mixtures of at least two of these products.

7. Composition according to any one of claims 1 to 6, characterized in that the starchy material is chosen from native starches, pregelatinized starches, extruded starches, atomized starches, fluidized starches, oxidized starches, starches. cationic, anionic starches, hydroxyalkylated starches, crosslinked starches, starch acetates, fatty starch and fatty chain esters of 4 to 22 carbons, dextrins, maltodextrins and any mixtures of these products.

8. Composition according to any one of claims 1 to 7, characterized in that the plasticizing agent of the starchy material has a molar mass less than 1000, preferably less than 400, and more preferably at most equal to 380.

9. Composition according to any one of claims 1 to 8, characterized in that it contains at least 51%, preferably at least 70%, in particular more than 80%, of biosourced materials based on carbon of origin renewable, expressed as dry weight relative to the dry weight of said composition.

10. Composition according to any one of claims 1 to 9, characterized in that it is non-biodegradable or non-compostable.

11. Composition according to any one of claims 1 to 10, characterized in that it simultaneously presents:

a maximum tensile stress greater than 50 MPa, in particular greater than 55 MPa.

12. Composition according to any one of claims 1 to 11, characterized in that it has a flexural modulus (ISO 178) and a tensile modulus (ISO 527) greater than 1500 MPa, especially greater than 2000 MPa.

13. Composition according to any one of claims 1 to 12, characterized in that it has a density of between 1.05 and 1.25, preferably between 1.1 and 1.2.

14. Composition according to any one of claims 1 to 13, characterized in that it further contains, preferably at a rate of 1 to 15% by weight (dry / dry), an agent improving its impact resilience. , in particular at a temperature of 23 ° C. or below, said agent being in particular chosen from the group comprising ethylene-propylene, ethylene-styrene or styrene-butadiene co-polymer polymers and natural rubber-type elastomeric materials, styrene copolymer -butylene-styrenes (SBS) or styrene-ethylene-butylene-styrenes (SEBS).

15. Composition according to any one of claims 1 to 14, characterized in that it contains, in addition, a polymer or a copolymer other than a polyolefin selected from the group comprising polyurethanes (PU), thermoplastic polyurethanes ( TPU), polyamides, polylactates (PLA), polybutylenes succinates (PBS, PBSA), polyhydroxyalkanoates (PHA, PHB, PHBV) and any mixtures thereof.

Process for the preparation of a thermoplastic composition according to any one of claims 1 to 15, said process comprising the following steps:

granular starches, native or modified,

- co-products of starch manufacture, milling, candy, paper mill or oil mill,

cellulosic or lignocellulosic fibers,

- algae and algae extracts,

and any mixtures of at least two of these products, and

17. The method of claim 16, characterized in that the composition (a) contains:

a) from 17 to 65%, preferably from 20 to 65%, of at least one starchy material, a) from 12 to 30%, preferably from 12 to 25%, of at least one plasticizing agent of starchy material , and

b) from 17 to 70%, preferably from 17 to 65%, of at least one polyolefin, these percentages being expressed by dry weight relative to the dry weight of said composition (a).

18. The method of claim 17, characterized in that the composition (a) contains:

a) from 25 to 60% of at least one starchy material,

b) from 15 to 25% of at least one plasticizing agent of starchy material, and c) from 25 to 60% of at least one polyolefin.

19. Process for improving the adhesiveness or the bonding between them of fibers and / or vegetable fillers, characterized in that it comprises the following steps: (i) selecting at least one plant material selected from vegetable fibers and vegetable fillers,

(ii) selecting at least one composition containing a plasticized starchy material with a plasticizer with a molar mass greater than 18 g / mol and less than 5000 g / mol and a polyolefin, and

(iii) thermomechanical mixture of said plant material and said composition.

20. Process for improving the compatibility between a plant material and a polyolefin, characterized in that it comprises the following steps:

(i) selecting at least one plant material selected from vegetable fibers and vegetable fillers and at least one polyolefin,

(ii) selecting at least one plasticized starchy material by a plasticizer with a molar mass greater than 18 g / mol and less than 5000 g / mol, and (iii) a thermomechanical mixture, of the plant material and of the polyolefin in the presence of said material. amylaceous so as to improve the plant material / polyolefin compatibility within the resulting thermoplastic composition.

21. Method according to any one of claims 16 to 20, characterized in that step (iii) is conducted at a temperature between 80 and 200 ° C, preferably between 120 and 185 ° C and more preferably still between 160 and 180 ° C.