FR3016364A1 - STARCH BASED MIXTURE COMPRISING A GRAFT POLYOLEFIN - Google Patents

Abstract

The invention thus relates to a thermoplastic composition comprising: a thermoplastic starch consisting of at least one starch and at least one plasticizer of the starch; At least one polyolefin grafted with at least one functional compound carrying at least one polar function; and characterized in that the amount of thermoplastic starch is greater than 55% by weight, based on the total mass of the composition. This composition allows an advantageous use as a masterbatch.

Description

The invention relates to a composition based on grafted polyolefin and thermoplastic starch useful as a masterbatch. State of the art The development of plastics derived from renewable resources in the short term has become an economic imperative, in the face of the depletion and rising prices of fossil fuels such as oil. In addition, these plastics are often incinerated at the end of their life, which implies a release of carbon dioxide that was previously stored as fossil carbon. It has been shown by the scientific community that the carbon dioxide emitted contributes significantly to the global warming observed in recent decades. In the field of packaging, these phenomena are particularly important because this field uses large quantities of plastic material, and the packaging is rarely recycled at the end of its life and is generally incinerated. Most of these packages are currently made from polyolefins, such as polyethylene or polypropylene.

Some of these polyolefins have rheological properties that allow them to be converted, at relatively low temperature for thermoplastic polymers, into monolayer or multilayer films. The films thus obtained have very interesting properties of permeability and mechanical strength, and this in particular for the manufacture of film and packaging bag. However, a disadvantage of these polyolefins is that they are currently obtained for the most part by polymerization of olefins of petrochemical origin. It is therefore necessary to develop plastics from renewable resources, called "biobased", in order to reduce the quantities of plastics obtained from petroleum.

Thus, it has been proposed in recent years to develop polyesters which have a shaping temperature close to that of polyolefins, such as polybutylene succinate, and whose mechanical properties of the films are also similar. However, these polymers are biodegradable, which makes their use in some applications impossible, especially applications where the life of the product must be important. In addition, the price of these polymers is currently significantly higher than that of polyolefins. One of the solutions envisaged is to manufacture compositions based on thermoplastic starch, which consists of starch and plasticizer of this starch such as glycerol. Indeed, the manufacture of these compositions is advantageous because starch is one of the biobased polymers which is naturally the most widespread in the environment. However, these thermoplastic starches have insufficient properties, especially in terms of water resistance. In addition, the transformation of starch into thermoplastic starch is not easy because it requires the use of stresses and / or high temperatures during thermomechanical mixing, which tends to degrade the thermoplastic starch thus formed. To counteract these drawbacks, compositions based on polyolefin and plasticized starch have been developed. In these compositions, the thermoplastic starch phase is dispersed in the polyolefin phase. These compositions have numerous advantages, such as, for example, being at least partially biobased and having a very improved resistance to water relative to thermoplastic starch. However, in these compositions, polyolefins naturally have poor compatibility with thermoplastic starch. These compositions therefore very generally also comprise a functional polyolefin for improving the compatibility between the two phases. Examples of these compositions are disclosed in the documents EP 554939, WO 2010012041, WO 2009022195 A1, US 2011/0305886 and US Pat. No. 5,314,934. Despite these improved properties compared to compositions containing no functional polyolefin, these compositions exhibit at least one of the following disadvantages. Some of these compositions are difficult to transform by known techniques because they are too viscous. In addition, the water resistance of the compositions may be insufficient, which limits the scope of application, for example for indoor use. Some of these compositions may comprise amounts of thermoplastic starch, and therefore of biobased material, quite limited.

On the other hand, another problem is that the compositions may have poor mechanical properties. Indeed, these compositions are generally fragile and not very deformable. This is particularly disadvantageous for films, since their insufficient tear resistance prevents them from being used in many applications. In addition, although filmable, these compositions can not be easily used in extrusion blowing of sheath, or even extrusion of flat die films (English cast extrusion). Indeed, using these compositions, we can observe many holes (also called "tears") in the films obtained. It can also be noted that the film obtained generally has aesthetic defects, including the presence of gels. These phenomena are exacerbated when the composition is converted into a film with a conversion machine using high industrial rates.

Another disadvantage is that these compositions are not always suitable for the manufacture of multilayer films. Furthermore, it should be noted that the composition may be manufactured from an intermediate composition which comprises a large amount of thermoplastic starch, the latter may be greater than 55% by weight, and according to a process in which this intermediate composition is thermomechanically mixed with an unfunctionalized polyethylene. This intermediate composition may be called "starch masterbatch", subsequently "masterbatch".

An advantage of these masterbatches is that they can be easily implemented, the end-product manufacturers can thus easily formulate final thermoplastic compositions by mixing the various constituents of this composition. These masterbatches give the processor more freedom over the formulations of the final thermoplastic compositions. According to the present invention, the term "final thermoplastic composition" is a thermoplastic composition directly used for the manufacture of an object. This can be of any type (for example a film, a sheet, a tray, a bottle, a bottle, a reservoir, a pocket, a tube, etc.) and is obtained by standard thermoplastic processing techniques. The final thermoplastic composition may comprise, in addition to the polymers constituting it, optional constituents which may be additives, dyes, fillers, fibers.

Among the documents describing thermoplastic compositions comprising thermoplastic starch and polyethylene, mention may also be made of WO2011009165 which describes multilayer films, comprising at least a three-layer structure made of a layer of core polymer and of two layers of polymer surrounding said core layer, said core layer comprising a melt blend of polyethylene, thermoplastic starch and ethylene-acrylic acid copolymer. According to one embodiment of this document, the core polymer layer of the trilayer structure can be obtained by extrusion of a masterbatch and additional polyethylene, said masterbatch comprising thermoplastic starch and an ethylene-acid copolymer. acrylic. It is also by using such a method that the compositions of the core polymer layers are manufactured in the examples.

However, one of the problems of these starch-based and ethylene-acrylic acid masterbatches is that they are difficult to manufacture because they thermally degrade during their preparation. Indeed, they are generally very viscous during their processing, and thus require the use of constraints and / or high temperatures during their manufacture. This is mainly due to the amount of thermoplastic starch included in this masterbatch, which is known to present significant problems of degradation during its transformation.

The Applicant has therefore conducted research to solve these problems and has achieved a useful composition as a masterbatch, whose thermal degradation is limited during its preparation. It also makes it possible to provide, by mixing it with an additional polyethylene, final thermoplastic compositions with improved properties.

SUMMARY OF THE INVENTION The subject of the invention is thus a thermoplastic composition useful as a masterbatch, said composition comprising: a thermoplastic starch consisting of at least one starch and at least one starch plasticizer ; at least one polyolefin grafted with at least one functional compound bearing at least one polar function; and being characterized in that the amount of thermoplastic starch is greater than 55% by weight, based on the total mass of the composition.

The polyolefin grafted with at least one functional compound bearing at least one polar function (or "functional polyolefin") is preferably chosen from: a functional polyolefin A which is at least one copolymer of propylene and at least one second alpha olefin grafted with said functional compound, this copolymer comprising, based on its total mass, from 45 to 95% by weight of units derived from propylene; a functional polyolefin B which is at least one functional polyolefin mixture comprising a polyethylene grafted with said functional compound and a polyethylene wax grafted with said functional compound; a functional polyolefin C which is a functional polyolefin which is a copolymer of ethylene; at least one ester (X) selected from vinyl esters of carboxylic acid and esters of (meth) acrylic acid; and optionally at least one additional monomer copolymerized with the ethylene and the ester (X); said copolymer being further grafted with said functional compound; and a functional polyolefin D which is a polypropylene grafted with said functional compound whose melt flow index is from 120 to 155 cm3 / 10 min (ASTM D 1238, 190 ° C., 2.16 kg). ). The Applicant has observed that the polyolefins grafted with at least one functional compound carrying at least one polar function, and in particular the functional polyolefins A, B, C and D, are easily mixed with the starch and the plasticizer. Without being bound to any theory, the Applicant is of the opinion that this allows a lower thermal degradation of the composition according to the invention compared to compositions useful as masterbatches of the prior art. The Applicant has also been able to find better properties for the final thermoplastic compositions obtained from these masterbatches.

The Applicant believes that this improvement is also due to the fact that these particular functional polyolefins bind very well with the thermoplastic starch within the thermoplastic composition, and this although the chemical nature of the functional polyolefin is very different from that of the thermoplastic. starch or plasticizer of the starch. These improvements are all the more notable as the choice of these polyolefins makes it possible to limit the degradation of the thermoplastic starch during the preparation of the composition according to the invention. It follows that the final thermoplastic composition has improved mechanical properties. Moreover, this final thermoplastic composition can be advantageously used for the manufacture of films, since it is particularly well filmable, including on film forming machines such as extruders for extrusion blow-molding, or even extruders of flat die film. It is specified that the various variants of the invention presented above and below are of course combinable with each other.

DETAILED DESCRIPTION OF THE INVENTION The subject of the invention is a thermoplastic composition comprising: a thermoplastic starch consisting of at least one starch and at least one plasticizer for the starch; at least one polyolefin grafted with at least one functional compound carrying at least one polar function. wherein the amount of thermoplastic starch in the composition is greater than 55% by weight, based on the total mass of the composition.

A thermoplastic composition is a composition that reversibly softens under the action of heat and hardens on cooling to room temperature. It has at least one 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 -150 ° C to 0 ° C. This starch-based composition can, of course, be shaped by the processes traditionally used in plastics, such as extrusion, injection, molding, blowing and calendering. Its viscosity, measured at a temperature of 100 ° C. to 200 ° C., is generally between 10 and 106 Pa.s.

It is specified that the thermoplastic composition according to the invention is obviously obtained after thermomechanical mixing in the molten state, this mixture for transforming starch into thermoplastic starch and intimately mixing the constituents of the composition.

Thermoplastic Starch In the composition according to the invention, the thermoplastic starch is obtained by thermomechanical mixing of constituents comprising plasticizer and starch.

The amount of thermoplastic starch in the composition is according to the invention greater than 55% of its total mass. Advantageously, the amount of thermoplastic starch is greater than or equal to 60% by weight, preferably greater than 65%, most preferably greater than 70%, relative to the total mass of the composition. The amount of thermoplastic starch is generally less than 90% of the total mass of the composition, advantageously less than 85%, preferably less than 80%.

Starch The starch included in the composition may be of any type. If it is desired to obtain a composition of lower cost, the starch preferentially used for the manufacture of the composition is a granular starch, preferably a native starch.

The term "granular starch" is used herein to mean a starch which is native or physically modified, chemically or enzymatically, and which has retained, within the starch granules, a semicrystalline structure similar to that evidenced in starch grains. naturally occurring in reserve organs and tissues of higher plants, particularly in cereal grains, legume seeds, potato or cassava tubers, roots, bulbs, stems and fruits. 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. Granular starch, placed under polarized light, has a characteristic black cross, so-called Maltese cross, typical of the granular state. According to the invention, the granular starch can come from all botanical origins, including a granular starch rich in amylose or conversely, rich in amylopectin (waxy). It may be starch native to cereals such as wheat, maize, barley, triticale, sorghum or rice, tubers such as potato or cassava, or legumes such as peas and soybeans, and mixtures of such starches.

According to one variant, the granular starch is an acid hydrolyzed, oxidizing or enzymatic starch, or an oxidized starch. It can be a starch commonly called fluidized starch or a white dextrin. According to another variant, it may also be a starch modified physico-chemically but having essentially retained the structure of the native starch starting, such as in particular esterified and / or etherified starches, in particular modified by acetylation , hydroxypropylation, cationization, crosslinking, phosphatation, or succinylation, or starches treated in aqueous medium at low temperature (in English "annealing"). Preferably, the granular starch is a native, hydrolysed, oxidized or modified starch, in particular corn, wheat or pea.

Granular starch generally has a degree of soluble at 20 ° C in demineralized water, less than 5% by weight. It is preferably almost insoluble in cold water. According to a second variant, the starch selected as starch useful in the manufacture of the composition is a water-soluble starch, which may also come from all botanical origins, including a water-soluble starch rich in amylose or conversely, rich in amylopectin (waxy). This water-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 starchy component which, at 20 ° C. and with mechanical stirring for 24 hours, has a soluble fraction in demineralized water of at least 5% by weight. This soluble fraction is preferably greater than 20% by weight and in particular greater than 50% by weight. Of course, the water-soluble starch can be totally soluble in demineralized water (soluble fraction = 100%).

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 any mixture of these products.

The pregelatinized starches may 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, then drying for example. in an oven, 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. By way of example, mention may be made of the 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 demineralized water at 20 ° C generally greater than 90%, or even 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 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 acetylation in aqueous phase with acetic anhydride, by reaction with mixed anhydrides, by hydroxypropylation in the glue phase, by cationization in dry phase or glue phase, by anionization in dry phase or glue phase. by phosphatation or succinylation. The water-soluble highly functionalized starches obtained 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.

Advantageously, the water-soluble starch is a water-soluble starch of corn, wheat or peas, or a water-soluble derivative thereof. In addition, it advantageously has a low water content, generally less than 10%, preferably less than 5%, in particular less than 2.5% by weight, and ideally less than 0.5%, or even less than 0%, 2% by weight.

According to a third variant, the amylaceous component selected for the preparation of the composition 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 starchy component 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 having a starch crystallinity level of less than 5%, generally less than 1% and especially zero. It is also preferably "organosoluble", that is to say having 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, including having a low water content, ie less than 10% by weight. It may especially be less than 5%, in particular less than 2.5% 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 functionalization of the native or modified starches such as those presented above. This 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 organic solvents above. 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 acetylation in the solvent phase with 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, silylation, butadiene telomerization. These organomodified, preferably organosoluble, highly functionalized starches can be, in particular, 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 starch, dextrins or maltodextrins, in particular having a DS between 0 , 8 and 2.8. Advantageously, the organomodified starch is an organomodified starch of corn, wheat or pea or an organomodified derivative thereof. The composition advantageously comprises, relative to its total mass, from 40 to 65% by weight, preferably from 45 to 60% by weight, more preferably from 45 to 55% by weight, of starch, expressed as dry weight relative to to the total mass of the composition. Starch plasticizer The composition further comprises a starch plasticizer, whose function is to destructure the starch. This plasticizer can be of any type. The plasticizer advantageously has a molar mass of less than 1000 g / mol, and in particular less than 400 g / mol / l. The plasticizer of the starch, especially when the latter is organomodified, is preferably chosen from methyl, ethyl or fatty esters of organic acids such as lactic, citric, succinic, adipic and glutaric acids and esters. acetic or 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), 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. The plasticizer of the starch is advantageously chosen from glycerol, sorbitol, mannitol, maltitol, oligomers of these polyols, polyethylene glycol, urea or a mixture of these plasticizers. Preferably, the plasticizer is a mixture of sorbitol and glycerol. Most preferably, the plasticizer comprises, with respect to its total mass, at least 50% by weight of sorbitol. The composition advantageously comprises, relative to its total mass, from 10 to 35% by weight of plasticizer, preferably from 15 to 30%, more preferably from 20 to 25%. The plasticizer is generally present in the composition in a proportion of 1 to 150 parts by weight, preferably in the proportion of 25 to 120 parts by weight and in particular in the proportion of 30 to 60 parts by weight per 100 parts by weight of starch. Functional polyolefins The selection of the functional polyolefin has allowed the Applicant to obtain a thermoplastic composition useful as a masterbatch, which is particularly advantageous. The functional polyolefin useful in the invention is a polyolefin grafted with at least one functional compound carrying at least one polar function. In other words, the functional polyolefin comprises units derived from the grafting of a functional compound onto a polyolefin. According to the invention, the term "polyolefin" means a polymer obtained from olefinic monomers, these olefinic monomers preferably comprising ethylene and / or propylene. The functional compound carrying a polar function preferably has, before grafting, a dipole moment greater than 1, preferably greater than 2, most preferably greater than 3 Debyes.

The functional compound preferably comprises at least one oxygen atom. This functional compound carries a polar function and preferably comprises at least one carbon-carbon double bond. It is preferably selected from unsaturated carboxylic acid anhydrides, unsaturated carboxylic acids, unsaturated oxiranes and unsaturated silanes, preferentially maleic anhydride.

The carboxylic acid anhydride preferably comprises from 4 to 30 carbon atoms; it may be chosen, for example, from maleic, itaconic, citraconic, allylsuccinic, cyclohex-4-ene-1,2-dicarboxylic anhydride, 4-methylenecyclohex-4-ene-1,2-dicarboxylic anhydride and bicyclo (2,2, 1) hept-5-ene-2,3-dicarboxylic acid.

The unsaturated carboxylic acid preferably comprises from 2 to 30 carbon atoms, and may be chosen in particular from acrylic acid and methacrylic acid. The unsaturated oxirane, also called unsaturated epoxide, can be chosen from aliphatic glycidyl esters and ethers such as glycidyl allyl glycidyl ether, vinyl glycidyl ether, maleate and itaconate, glycidyl acrylate and methacrylate, and esters. and alicyclic glycidyl ethers such as 2-cyclohexene-4,5-diglycidylcarboxylate, cyclohexene-4-glycidyl carboxylate, 5-norbornene-2-methyl-2-glycidyl carboxylate and endo-cis-bicyclo (2, 2.1) -5-heptene-2,3-diglycidyldicarboxylate. Preferably, the unsaturated oxirane is chosen from acrylate and glycidyl methacrylate. The unsaturated silane may be chosen from 3-methacryloyloxypropyltrialkoxysilanes, 3-methacryloyloxypropyldialkoxyalkylsilanes, methacryloyloxymethyltrialkoxysilanes, (methacryloyloxymethyl) dialkoxysilanes, vinyldialkoxyalkylsilanes and vinyltrialkoxysilanes.

Most preferably, maleic anhydride is used as the unsaturated functional compound. Advantageously, the functional polyolefin comprises, relative to its total weight, from 0.1 to 5% by weight of functional compound, advantageously from 0.5 to 2% by weight. The amounts of the various monomers in the functional polyolefin can be determined by conventional methods, typically by Fourier transform infrared spectroscopy.

Preferably, the grafted polyolefin is chosen from at least one of the functional polyolefins A, B, C and / or D as defined above and which are now described in detail.

Functional Polyolefin A The functional polyolefin A is at least one copolymer of propylene and at least one second alpha-olefin further grafted with at least one functional compound carrying at least one polar function, said copolymer comprising, with respect to its total mass, from 45 to 95% by weight of units derived from propylene.

The functional polyolefin is obtained by grafting the functional compound onto a copolymer of propylene and alpha-olefin. In other words, the functional polyolefin is preferably a copolymer of propylene and alpha-olefin grafted with a functional compound.

This copolymer of propylene and alpha-olefin may be a block copolymer or a random copolymer. The second alpha-olefin other than propylene may be chosen from ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene and 1-decene. . It is advantageously chosen from ethylene or 1-butene, preferably ethylene. The functional polyolefin A may comprise, relative to its total mass, from 4 to 40% by weight of units derived from alpha-olefin other than propylene.

The functional polyolefin A advantageously comprises from 55 to 95% of units derived from propylene, preferably from 70 to 94%, for example from 78 to 92.5% by weight of propylene. According to one variant, the functional polyolefin A comprises, with respect to its total mass: from 50 to 95% of propylene; from 4 to 40% of alpha-olefin other than propylene; more than 0% and less than 10% of functional compound; the total of the aforementioned constituents being equal to 100%. According to an advantageous variant, the functional polyolefin A may comprise, based on its total mass: from 55 to 95% of propylene; from 4 to 40% of alpha-olefin other than propylene; from 0.05% to 7% of functional compound; the total of the aforementioned constituents being equal to 100%. Preferably, the functional polyolefin A comprises, with respect to its total mass: from 70 to 94% of propylene; from 5 to 25% of alpha-olefin other than propylene; from 0.1% to 5% of functional compound; the total of the aforementioned constituents being equal to 100%.

Most preferably, the functional polyolefin A comprises, with respect to its total mass: from 78 to 92.5% of propylene; - from 6.5 to 20% alpha-olefin different from propylene; from 0.5% to 2% of functional compound; the total of the aforementioned constituents being equal to 100%. The functional polyolefin A may have a density ranging from 0.855 to 0.900, for example from 0.860 to 0.880. The functional polyolefin A advantageously has a melt flow index (MFI) (2.16 kg, 190 ° C., ASTM D-1238) ranging from 0.1 to 200 g / 10 min, for example from 1 to 50 g / 10 min, most preferably from 5 to 30 g / 10 min. It preferably has a melting point of 40 ° C. to 140 ° C., for example 60 ° C. to 100 ° C.

Functional Polyolefin B The grafted polyethylene carrying at least one polar function and the grafted polyethylene wax carrying at least one polar function included in the functional polyolefin B are obtained by grafting said functional compound, respectively on a polyethylene and a wax of polyethylene.

Preferably, the mixture of functional polyolefins is obtained by co-grafting a mixture of polyethylene and a polyethylene wax with a functional compound carrying at least one polar function, that is to say that the grafting of the polyolefins. two polymers is produced simultaneously. The polyethylene and the polyethylene wax may be obtained by radical polymerization, in particular by high-pressure polymerization or catalytically, for example by Phillips, Ziegler-Natta or metallocene catalysis. The functional polyolefin blend may comprise, based on the weight of functional polyolefins: from 60 to 99% grafted polyethylene; from 1 to 40% of grafted polyethylene wax. Advantageously, the mixture of functional polyolefins comprises, relative to the weight of functional polyolefins: from 70 to 96% of grafted polyethylene; from 4 to 30% of grafted polyethylene wax. Preferably, the mixture of functional polyolefins comprises, relative to the weight of functional polyolefins: from 80 to 95% of grafted polyethylene; from 5 to 20% of grafted polyethylene wax. The functional polyolefin B can have a density ranging from 0.855 to 0.950, for example from 0.890 to 0.920.

The grafted polyethylene wax may have a number-average molar mass ranging from 500 to 10,000 g / mol, for example from 800 to 6,000 g / mol. Advantageously, the grafted polyethylene wax has a fluidity greater than 100, for example greater than 200, preferably greater than 400 cm3 / 10min (ASTM D 1238, 190 ° C., 2.16 kg). The grafted polyethylene has a number-average molar mass greater than that of the grafted polyethylene wax, for example greater than 10,000 g / mol, typically ranging from 11,000 to 10,000,000 g / mol, for example from 20,000 g / mol to 300,000 g / mol. mol. The fluidity of the grafted polyethylene is advantageously from 0.1 to 90, for example from 0.5 to 50 cm3 / 10min (ASTM D 1238, 190 ° C., 2.16 kg).

As explained above, the grafted polyethylene wax differs mainly from the grafted polyethylene in that its molar mass is lower.

As a result, its melt viscosity is also higher than that of a grafted polyethylene. Grafted polyethylenes are sold, for example, under the brand name Bondyram® by the company Polyram, Orevac® by the company Arkema® or by Fusabond® by the company DuPontTM Grafted polyethylene waxes are marketed under the trademark Licocene® by the company Clariant® .

Functional Polyolefin C Functional polyolefin C is a functional polyolefin which is a copolymer of ethylene; at least one ester (X) selected from vinyl esters of carboxylic acid and esters of (meth) acrylic acid; and optionally at least one additional monomer copolymerized with the ethylene and the ester (X); said copolymer being further grafted with at least one functional compound carrying at least one polar function.

According to the invention, this copolymer is obtained by a first polymerization step of monomers, called "reactive monomers", comprising ethylene and at least one ester (X) chosen from vinyl esters of carboxylic acid and esters of (meth) acrylic acid, followed by a second step of grafting the copolymer formed in the first step with a functional compound. According to a first variant, the ester (X) is an alkyl acrylate or an alkyl methacrylate, these compounds being commonly grouped under the name "alkyl (meth) acrylate". The alkyl groups of these (meth) acrylates can have up to 30 carbon atoms. Mention may be made, as an alkyl group, of methyl, ethyl, propyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl and tridecyl groups. tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, hencosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl. Preferably, the alkyl chain of the (meth) acrylate comprises from 1 to 8 carbon atoms, preferably from 1 to 4. The alkyl (meth) acrylate is preferably selected from methyl acrylate, methyl methacrylate, ethyl acrylate and butyl acrylate. According to a second variant, the ester (X) is a vinyl ester of carboxylic acid. Vinyl esters include vinyl acetate, vinyl versatate, vinyl propionate, vinyl butyrate and vinyl maleate. The reactive monomers useful for forming the copolymer may optionally comprise at least one additional monomer copolymerized with ethylene and the ester (X). This additional monomer is of course capable of copolymerizing with ethylene and the ester (X) and can be an unsaturated carboxylic acid anhydride, an unsaturated carboxylic acid, an unsaturated oxirane, an unsaturated silane or a mixture of these monomers. The optional additional monomer is advantageously chosen from unsaturated carboxylic acid anhydrides, preferentially maleic anhydride.

Advantageously, the copolymer is an ethylene-alkyl (meth) acrylate copolymer grafted with at least one functional compound or an ethylene (meth) acrylate-maleic anhydride copolymer grafted with at least one functional compound.

A most preferred functional polyolefin is a graft copolymer which comprises, based on its total weight: from 50 to 96.9% of ethylene, preferably from 65 to 92%; from 3 to 40% of at least one ester (X) chosen from vinyl esters of carboxylic acid and esters of (meth) acrylic acid, preferably from 5 to 30%; optionally from 0.1 to 10% by weight of at least one additional monomer copolymerized with the ethylene and the ester (X); from 0.1 to 5% by weight of grafted functional compound, preferably from 0.5 to 2%, the total of the abovementioned constituents being equal to 100%. Functional Polyolefin D Functional polyolefin D is a polypropylene grafted with at least one functional compound carrying at least one polar function whose melt volume melt index is from 120 to 155 cm3 / 10 min (ASTM D 1238, 190 ° C, 2.16 kg).

Preferably, its melt volume melt index is 130 to 152 cm3 / 10 min, most preferably 135 to 150 cm3 / 10 min. The functional polyolefin D of the composition advantageously has a melting temperature of 140 ° C to 200 ° C, for example 150 ° C to 195 ° C. The functional polyolefin D is obtained by grafting the functional compound onto a polypropylene. The polypropylene is preferably a homopolymer of propylene. This polypropylene is generally obtained by catalytic polymerization of propylene. These grafted polypropylenes are sold, for example, under the brand name Bondyrame by the company Polyram, Orevac® by the company Arkema® or by Fusabonde by the company DuPontTM Preparation of the functional polyolefins As indicated above, the functional polyolefin is obtained by grafting the functional compound onto a polyolefin .

The grafting of the polyolefins is an operation known per se and the skilled person will be able to adapt the following process to obtain the functional polyolefin desired and useful to the invention. The grafting reaction can be carried out according to a batch process (or batch) in solution or, preferably, in a continuous process with a melt mixing tool, these processes being well known to those skilled in the art. As a melt-blending tool, internal mixers, roll mixers, single-screw, counter-rotating or co-rotating twin-screw extruders, planetary extruders, continuous co-kneaders can be used. The grafting tool can be one of the tools mentioned above or their combination, such as for example a co-kneader associated with a single-screw extruder, or a co-rotating twin-screw extruder associated with a pump. In the case of an extrusion, the tool preferably comprises a melting zone of the polymer, a zone of mixing and reaction between the species present and an expansion / degassing zone for eliminating the volatile compounds. The tool may be equipped with a pumping system for the melt and / or a filtration system and / or a granulation system with rushes or underwater. The polyolefin to be grafted is introduced in the presence of a radical generator and the functional compound in the tool, the body temperature of which is regulated, this temperature being chosen in line with the kinetics of decomposition of the radical generator. As the radical generator for continuous grafting organic peroxides such as dialkyl peroxides, hydroperoxides or peroxyketals can be used. Preferentially, a temperature ranging from 100 to 300 ° C., more preferably from 180 to 250 ° C., is used. The polyolefin to be grafted, the functional compound and the radical generator can be introduced simultaneously or separately into the extrusion tool. In particular, the functional compound and / or the radical generator can be introduced either simultaneously with the copolymer as a main feed, or separately by injection along the tool. In the injection step, the functional compound and / or the radical generator may be combined with a fraction of a co-grafting agent of the copolymer, for example styrene. This fraction of co-grafting agent of the copolymer is intended to facilitate and accelerate the grafting of the functional agent and thus improve the yield of the reaction. During a relaxation / degassing step, a vacuum is applied adapted to devolatilize volatile compounds, the vacuum level may range from a few millibars to several hundred. The grafted polyolefin useful in the invention can be converted into the output of the extrusion tool into granules using a granulation tool, and then recovered in this form.

The functional polyolefin A is obtained by grafting the functional compound onto a copolymer comprising propylene and the second alpha-olefin. These copolymers are generally obtained by catalytic polymerization of propylene and the second alpha-olefin.

The propylene copolymers useful for grafting the functional polyolefin A may be block copolymers or random copolymers. They are marketed for example under the trademark Adflex® or Hifax by the company Lyondellbasell® or by Vistamaxxe by Exxonmobil®. If the functional compound is grafted onto a block copolymer, the functional polyolefin A obtained is a block copolymer. Conversely, if the functional compound is grafted onto a random copolymer, the functional polyolefin A obtained is a random copolymer. According to a mode of the invention, the copolymer useful for obtaining the functional polyolefin A is mixed before grafting with a second polyolefin thermomechanically to obtain a mixture of polyolefins. This polyolefin mixture is then grafted with the functional monomer. According to this embodiment, the copolymer and the second polyolefin are advantageously mixed in a mass ratio ranging from 10/90 to 90/10, preferably ranging from 30/70 to 70/30. With regard to the amounts of each of the constituents, it is specified that when a mixture comprising an amount M of copolymer and an amount N of a second polyolefin is grafted, it is considered that the graft mixture comprises this same quantity M of functional polyolefin. useful to the invention and this same amount N of second grafted polyolefin. Advantageously, the second polyolefin is a polyethylene, for example a polyethylene having a density of between 0.905 and 0.935.

In the case of the functional polyolefin B, the grafted polyethylene is obtained by grafting the functional compound onto a polyethylene. The grafted polyethylene wax is also obtained by grafting the functional compound onto a polyethylene wax. It is possible to carry out the graftings of the polyethylene and the polyethylene wax separately or by co-grafting a mixture of polyethylene and a polyethylene wax, that is to say the simultaneous grafting of this mixture. . In this case, it is sufficient to introduce into the grafting tool the polyethylene and the polyethylene wax, which are mixed before grafting, in order to obtain directly the functional polyolefin B. With regard to the quantities of each of the constituents, it is specified that when a mixture comprising a quantity M of polyethylene and a quantity N of polyethylene wax is grafted, it is considered that the polyolefin B thus obtained comprises this same quantity M of grafted polyethylene and this same quantity N of grafted polyethylene wax . According to the variant of functional polyolefin C, it is obtained by grafting an ethylene copolymer of at least one ester (X) chosen from vinyl esters of carboxylic acid and esters of (meth) acrylic acid. and optionally at least one additional monomer copolymerized with the ethylene and the ester (X). Examples of copolymers of ethylene and of ester (X) include ethylene-vinyl acetate copolymers, ethylene-methyl acrylate copolymers, ethylene-ethyl acrylate copolymers and ethylene-ethyl acetate copolymers. butyl acrylate. Ethylene-vinyl acetate copolymers are sold, for example, by Arkema® under the trade name EVATANE® or by DuPontTM under the trademark ELVAX®. The ethylene-alkyl acrylate copolymers are sold by the company Arkema® under the trade name LOTRYL® or by DuPontTM under the trademark ELVALOY®. By way of examples of copolymers of ethylene, of ester (X) and of additional monomer, mention may be made of ethylene-methyl acrylate-maleic anhydride copolymers, ethylene-ethyl acrylate-maleic anhydride copolymers, copolymers ethylene-butyl acrylate-maleic anhydride, ethylene-methyl acrylate-glycidyl methacrylate copolymers, ethylene-ethyl acrylate-glycidyl methacrylate copolymers and ethylene-butyl acrylate-glycidyl methacrylate copolymers. The ethylene-alkyl acrylate-maleic anhydride copolymers and ethylene-alkyl acrylate-glycidyl methacrylate copolymers are sold by Arkema® under the trademark LOTADER® or by DuPontTM under the trademark BYNEL®. According to a mode of the invention, the copolymer useful for obtaining the functional polyolefin is mixed before grafting with a second polyolefin thermomechanically to obtain a mixture of polyolefins. This polyolefin mixture is then grafted with the functional monomer. According to this embodiment, the copolymer and the second polyolefin are advantageously mixed in a mass ratio ranging from 10/90 to 90/10, preferably ranging from 30/70 to 70/30. With regard to the amounts of each of the constituents, it is specified that when a mixture comprising an amount M of copolymer and an amount N of a second polyolefin is grafted, it is considered that the graft mixture comprises this same quantity M of functional polyolefin. useful to the invention and this same amount N of second grafted polyolefin. Advantageously, the second polyolefin is a polyethylene, for example a polyethylene having a density of between 0.905 and 0.935. As for the functional polyolefin D, it can be obtained by grafting the functional compound onto a polypropylene.

According to one embodiment of the invention, the polypropylene useful for obtaining the functional polyolefin is mixed before grafting with a second polyolefin thermomechanically to obtain a mixture of polyolefins. This polyolefin mixture is then grafted with the functional monomer. This graft mix has the particular melt volume melt index of the invention. An advantage of using this grafted mixture with a functional monomer is that the composition comprising this grafted mixture has a higher water resistance. According to this embodiment, the polypropylene and the second polyolefin are advantageously mixed in a mass ratio ranging from 10/90 to 90/10, preferably ranging from 30/70 to 70/30. With regard to the amounts of each of the constituents, it is specified that when a mixture comprising an amount M of polypropylene and a quantity N of a second polyolefin is grafted, it is considered that the grafted mixture comprises this same quantity M of functional polyolefin. useful to the invention and this same amount N of second grafted polyolefin. Advantageously, the second polyolefin is a polyethylene, for example a polyethylene having a density of between 0.905 and 0.935.

The composition comprises, with respect to its total mass, less than 50% by weight of functional polyolefin. Advantageously, the composition comprises, with respect to its total mass, from 2 to 45% by weight of functional polyolefin, preferably from 3 to 25%, most preferably from 5 to 15%, more preferably from 7 to 15%. It is understood that the total of the constituents of the composition is equal to 100%.

Other constituents According to a preferred variant, the composition according to the invention further comprises at least one polyethylene having a density of between 0.865 and 0.935. This polyethylene may be chosen from very low density polyethylene, low density polyethylene, linear low density polyethylene or a mixture of these polymers. Advantageously, the density of the polyethylene is between 0.890 and 0.935, preferably between 0.910 and 0.935. The optional polyethylene may be obtained by radical polymerization, in particular by high-pressure polymerization or catalytically, for example by Phillips, Ziegler-Natta or metallocene catalysis. The composition advantageously comprises, relative to its total mass, from 0 to 40% by weight of optional polyethylene (inclusive), for example between 0 and 25% (excluded), advantageously from 5 to 20% (inclusive), better, from 10 to 20%, it being understood that the total of the constituents of the composition is equal to 100%. It is understood that the total of the constituents of the composition is equal to 100%. This optional polyethylene is not grafted with a functional compound and preferably does not comprise a monomer carrying a polar function.

The composition according to the invention may furthermore comprise, relative to its total mass, between 0 and 20% of optional constituent other than starch, the plasticizer of the starch, the functional polyolefin and the optional polyethylene, preferably between 0.1 and 5%, it being understood that the total of the constituents of the composition is equal to 100%.

This optional component may be selected from among the additives and polymers other than starch, functional polyolefin and polyethylene.

The optional polymer may thus be a functional polyolefin other than the functional polyolefin useful for the invention. In the case where the functional polyolefin is included in a graft mixture of polyolefins as described above, the composition therefore also comprises a certain amount of grafted second polyolefin other than the functional polyolefin useful for the invention. The additives, customary in the manufacture of thermoplastics, are capable of improving at least one of the final properties of the composition and / or of facilitating the method of manufacturing said composition. The usual additives may be chosen from additives which make it possible to improve the stability and the preservation of the composition, in particular the antioxidants, the stabilizers, the UV absorbers and the antimicrobials; process aid additives, including lubricating agents, antiblocking agents, mold release agents and anti-blocking agents; antistatic agents, optical brighteners, dyes or pigments, nucleating agents, flame retardants, printing promoters, anti-electrostatic agents, antifoggants and blowing agents. The composition may also comprise as usual additives reinforcements or fillers, for example natural plant fibers such as sawdust, wood fibers or hemp fibers. The composition according to the invention preferably comprises additives which make it possible to improve the stability and the preservation of the composition and the process aid additives. However, the skilled person will prefer for the other additives, reinforcements and fillers, not to mix with the composition according to the invention useful as a masterbatch; rather, it will prefer to select and add these constituents according to the intended final application, by adding them especially during the manufacture of the final thermoplastic composition, for example during the step of mixing the composition according to the invention with the additional polyethylene as explained later in the description of the final thermoplastic composition. The optional constituent may also be an additive providing the function of binding agent between the starch, the plasticizer and / or the functional polyolefin, this binding agent being chosen 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. Advantageously, the amount of binding agent ranges from 0.01 to 15% by weight of the composition, preferably from 0.1 to 5%, it being understood that the total of the constituents of the composition is equal to 100%. A list of these liaison agents is included in application WO2009095618 in the name of the Applicant. According to one preferred embodiment, the composition comprises, with respect to its total mass: from 45 to 55% by dry weight of starch; from 20 to 25% by weight of plasticizer; from 7 to 15% by weight of functional polyolefin; optionally from 10 to 20% by weight of polyethylene; optionally between 0.1 and 5% by weight of an optional component other than starch, the plasticizer of the starch, the functional polyolefin and the optional polyethylene, for example an additive; the amount of thermoplastic starch being greater than 70% by weight, it being understood that the total of the constituents of the composition is equal to 100%.

The composition according to the invention can be manufactured a manufacturing process using a conventional method of processing thermoplastics. The method of manufacturing the composition according to the invention comprises at least one step of mixing in the molten or softened state of the various constituents and a step of recovering the composition. This method can be carried out in internal mixers with blades or rotors, an external mixer, co-rotating or counter-rotating single-screw, twin-screw extruders. However, it is preferred to carry out this mixture by extrusion, in particular by using a co-rotating extruder. The mixture of the constituents of the composition can be at a temperature ranging from 80 to 300 ° C, for example from 100 to 250 ° C. In the case of an extruder, the various constituents of the composition can be introduced by means of introducing hoppers located along the extruder. The process described in WO2009095618 in which the thermoplastic starch is thermomechanically blended with the polyolefin and the functional polyolefin can be used. However, it is particularly preferred to use a process for preparing the composition comprising introducing the starch and a plasticizer thereof into a reactor containing a mixture of softened or fused polyolefin and functional polyolefin and kneading. the mixture obtained under conditions sufficient to obtain the plasticization of the starch by the plasticizer in order to obtain the composition according to the invention. This process is described in detail in application WO2010010282 in the name of the Applicant. The process for preparing the composition preferably comprises a step of removing volatiles such as water, for example using a vacuum pump.

When extrusion is used, a polymer rod is obtained which can be granulated using a granulator. Thus, the process preferably comprises a thermomechanical extrusion mixing step to obtain a polymer rod, followed by a granulation step of said rod to form polymer granules. Preferably, the composition according to the invention is in the form of granules, for example granules having a mean diameter ranging from 1 to 8 mm. The composition according to the invention advantageously has a melt flow rate index (MVR) (190 ° C., 10 kg) advantageously from 1 to 50 cm 3/10 min, more advantageously from 2 to 30 cm 3/10 min. preferably 5 to 20 cm3 / 10min. Surprisingly and despite the high amount of thermoplastic starch in the composition, the latter mixes quite satisfactorily with other components in a subsequent thermomechanical mixing step.

Another subject of the invention relates to the use of the composition as a masterbatch. In other words, the composition may be intended to be mixed in a thermoplastic manner with another constituent, in particular an additional polyethylene. This additional polyethylene may be of any type, for example chosen from the list of possible polyethylenes used for the manufacture of the composition according to the invention. The composition according to the invention can be used as a masterbatch using the conventional thermoplastic transformation methods already mentioned.

Another subject of the invention relates to a process for manufacturing a thermoplastic composition, previously defined as "final thermoplastic composition" as opposed to the composition according to the invention, comprising a step of thermomechanical mixing of the masterbatch according to the invention. invention with an additional polyethylene.

The mass quantity of masterbatch relative to the sum of the amounts of masterbatch and additional polyethylene can range from 5 to 95%, advantageously from 10 to 70%, preferably from 15 to 60%, most preferably from 20 to 55%. %. It is also possible to add other optional constituents to the composition according to the invention and to the additional polyethylene, the latter being able to be chosen from those mentioned in the previous part called "Other constituents". This thermomechanical mixing step is preferably carried out in an extruder, in particular by using a co-rotating extruder. This step of mixing the composition according to the invention and the additional polyethylene can be carried out at a temperature ranging from 80 to 300 ° C, for example from 100 to 250 ° C. In the case of an extruder, the various constituents of the composition can be introduced by means of introducing hoppers located along the extruder. The process for preparing the composition may comprise a step of removing volatiles such as water, for example using a vacuum pump.

The method may according to a first variant comprise a step of recovering the composition after cooling in the form of a rod and optionally a granulation step of this rod. In the latter case, the granules thus formed can be used again and transformed into any type of object using conventional thermoplastic processing techniques.

The method may according to a second variant comprise a transformation step, that is to say that the thermoplastic mixture is directly used before cooling in the conventional tools for processing thermoplastics.

The composition obtained from the masterbatch may allow the manufacture of articles. This article can be of any type, including a film, a sheet, a tray, a bottle, a bottle, a tank, a pocket, a tube, a pipe, a bucket, a box, a dashboard, a handle tool, a door handle or a carpet.

As explained above, these articles can be manufactured by conventional thermoplastic processing methods. It can thus be films obtained by extrusion-inflation or by extrusion on a flat die, molded parts, profiles obtained by extrusion, injected parts, parts obtained by thermoforming or rotational molding.

The articles may also include articles comprising a multilayer structure and wherein at least one of the layers comprises a composition obtained from a thermoplastic composition made from the masterbatch of the invention. The other layer (s) of the structure according to the invention may comprise at least one layer based on metal or organic polymer. It is specified that the term "based on" means that the layer comprises at least 10% by weight of said constituent (metal or organic polymer). Preferably, the organic polymer-based layer comprises at least 50% by weight of organic polymer, preferably at least 70%, in particular at least 90% of organic polymer. As organic polymers, mention may be made of: Homopolymers and copolymers of ethylene (PE) such as high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LDPE), ethylene-co-vinyl acetate copolymer (EVA), ethylene-alkyl coacrylate copolymers, ethylene-co-alkyl methacrylate copolymers, ethylene-co-acrylic acid copolymer, ethylene-co-methacrylic acid copolymer ethylene-co-vinyl alcohol copolymer (EVOH); polyvinyl alcohol (PVOH); homopolymers or copolymers of propylene (PP) such as isotactic polypropylene (iPP) or atactic polypropylene (aPP); homopolyamides and copolyamides (PA) such as polyamide 6 (PA6), polyamide 6.6 (PA6.6), polyamide 11 (PA11), polyamide 12 (PA12); homopolymers and copolymers of styrene such as crystal polystyrene, poly (styrene-co-butadiene), poly (styrene-co-acrylonitrile) (SAN), poly (acrylonitrile-co-butadiene-co-styrene) (ABS), poly (acrylonitrile-co-styrene-co-acrylate) (ASA); polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), poly (glycolic acid) (PGA), poly (lactic acid) (PLA), polycaprolactone (PCL), poly (butylene succinate) ) (PBS), poly (butylene adipate) (PBA), poly (ethylene succinate) and poly (ethylene adipate); chlorinated polymers and fluoropolymers; thermoplastic starches (TPS); or a mixture thereof.

Cellulose can also be mentioned as an organic polymer that is useful for the invention. Among the cellulose-based materials, there may be mentioned all types of modified celluloses, paper or cardboard. Preferably, the cellulose-based material is chosen from modified cellulose or not, paper or cardboard. The organic polymer-based layer may be in the form of a film, a woven or a nonwoven.

The metal-based layer may be metal, a metal alloy or a non-metallic component mixed with a metal. As an example of a metal that can be used in the multilayer structure, mention may be made of aluminum. These articles can be manufactured by a process comprising a step of coextruding the final thermoplastic composition with at least one other thermoplastic composition, in the case where the materials of the different layers are brought into contact in the molten state. By way of example, mention may be made of tube coextrusion, profile coextrusion and blow-molding co-extrusion techniques for bottles, flasks or reservoirs, generally grouped together under the same name. term of coextrusion blow molding of hollow body, co-extrusion inflation also called blowing of sheath (in English "film blowing") and co-extrusion flat ("in English" cast coextrusion "). They can also be manufactured according to a process comprising a step of applying a layer of molten polymer consisting of the final thermoplastic composition to a layer based on organic polymer, metal or adhesive composition in the state solid. This step may be carried out by pressing, overmolding, lamination or lamination, extrusion-rolling, coating, extrusion-coating or coating.

The conditions for converting the final thermoplastic composition to form monolayer or multilayer articles depend on the processing techniques employed. The article according to the invention may in particular be produced by a process comprising a thermomechanical mixing step at a temperature of between 100 and 250 ° C., preferably between 130 and 210 ° C., followed by a shaping step. The skilled person will find the conditions for the implementation of articles according to the invention. The final thermoplastic composition can be used for the production of films. Indeed, these films have excellent properties, superior to those of known films based on thermoplastic starch and polyolefin. These films can have a thickness ranging from 5 to 500. The final thermoplastic composition can be used for the production of monolayer or multilayer films. Indeed, an advantage of this composition is that it is very easily converted into monolayer film or multilayer film, especially by extrusion inflation or flat extrusion. This is not always the case for compositions based on thermoplastic starch and polyolefin: in this case, it is then necessary to reduce the rate of production in order to obtain a good quality film. Embodiments of the invention will now be described in detail in the following nonlimiting examples. EXAMPLES Example 1 Manufacture of Compositions According to the Invention and Comparative Constituents The constituents of the various compositions exemplified are presented below. It is specified that the melt indexes (MFI) of the various functional polyolefins and polyolefins are determined at 190 ° C. under 2.16 kg. - Polyolefin PO = LDPE Lupolen 1800 U - Functional Polyolefin The functional polyolefin is produced on a TSA extruder, Diameter 32, Length L / D = 50, for a flow rate of: 25 kg / h. The temperature profile of the extruder (ten zones of heating Z1 to Z10, temperature in ° C) is the following: 140/140/140/140/140/220/220/240/200/200 for a speed of screw 300 rpm

The polyolefin is introduced into the main hopper in the presence of 500 ppm of organic peroxide and the maleic anhydride is introduced into zone 4 of the extruder in order to obtain the various functional polyolefins PF1 to PF5. PF1 = copolymer of propylene and ethylene containing by mass 90.5% of propylene, 8.4% of ethylene grafted with 1.1% of maleic anhydride.

PF 2 = mixture of 49.45% by weight of a copolymer of propylene and ethylene containing by mass 91.5% of propylene, 8.5% of ethylene and 49.45% by weight of a LDPE, said mixture being grafted with 1.1% maleic anhydride. PF3 = Blend of 80% low density polyethylene and 20% polyethylene wax cografted with 1% maleic anhydride. PF4 = Copolymer comprising a mass content of 0.25% of copolymerized maleic anhydride, 28.7% of ethyl acrylate and 70% of ethylene, said copolymer being grafted with 1.05% of maleic anhydride in reactive extrusion. PF5 = Polypropylene grafted with 1% by weight of maleic anhydride, 850 MPa module, elongation at break of 10% and having a VCR of 140 cc / 10 min (190 ° C, 2.16 kg). CPF = Ethylene-acrylic acid copolymer comprising 9% acrylic acid. - Starch A = Wheat starch (containing 12.5% water) - PL plasticizer = Plasticizer mixture consisting of 50% sorbitol, 38% glycerol (3/0 in water (88% dry mass) ) - Additives PA = Process Aid AOP = Primary antioxidant Process for the manufacture of the composition The examples of this invention were carried out on a TSA extruder, Diameter 32, Length L / D = 50, for a flow rate of 30 kg / h - Temperature profile (sixteen heating zones Z1 to Z10, temperature in ° C): 50/80/120/150/170/170/180/180/180/190 for screw speed: 400 rpm. performs a bag premixing of the polyolefin and the functional polyolefin to form a polymer mixture.In the context of this process, is introduced into the extruder: - the polymeric mixture (polyolefin + functional polyolefin) in the main hopper the extruder, following which said mixture passes through all the heating zones of the extruder, - the plasticizer of the starch at the zone Z1 (5 to 110 D), the starch at the zone Z3 (10 to 15 D) and the degassing is carried out by the application of a partial vacuum in Z 6 (30-35 D) (100 mbar vacuum) to remove volatile compounds such as water.

Details of the Compositions The compositions according to the invention (Examples 1 to 5) and comparative compositions (Example 6) were carried out using the process described above. The amounts of the various constituents of the compositions are shown in Table 1. Note that the amounts of starch and plasticizer are with water. Table 1: Compositions according to the invention and comparative Composition Component Polyolefin Polyolefin Starch Plasticizer Additives I Functional Example Nature PO PF1 A PL PA AOP 1% introduced 13.6 9.0 54.0 23.0 0.3 0.1 Example Nature PO PF2 A PL PA AOP 2% introduced 13.6 9.0 54.0 23.0 0.3 0.1 Example Nature PO PF3 A PL PA AOP 3% entered 13.6 9.0 54.0 23.0 0.3 0.1 Example Nature PO PF4 A PL PA AOP 4% entered 13.6 9.0 54.0 23.0 0.3 0.1 Example Nature PO PF5 A PL PA AOP 5% entered 13.6 9.0 54.0 23.0 0.3 0.1 Example Nature PO CPF A PL PA AOP Comparative% Introduced 13.6 9.0 54.0 23.0 0.3 0.1 The compositions have a density of approximately 1.28. EXAMPLE 2 Mechanical Characterization of the Films Made with Compositions 1 to 4 Diluted at 30% in LDPE In order to evaluate their mechanical properties, the compositions of Example 1 are diluted 30% in low density polyethylene ( LDPE) Lupolen 2420 F by producing a dry mix introduced into an extruder, of Dr. COLLIN brand, Diameter 20, Length L / D = 18 and then used in the form of test specimens of films. The temperature profile is 170/175/180/180/180 ° C and the screw speed is 60 rpm. The mechanical properties are measured on the films obtained with a thickness of 50p.

Analytical Methods The properties of the various compositions detailed below were determined according to the analytical methods described below.

Measurement of the mechanical properties: Conditioning of the test pieces For carrying out the tests of characterization of the mechanical properties, the test pieces used are conditioned 24 hours at 20 ° C ± 2 ° C and 65% ± 5 (3/0 relative humidity according to the norm NF T51-014 Traction test The tensile mechanical characteristics of a composition are determined according to standard NF T51-034 (Determination of tensile properties) using a Lloyd Instrument LR5K test bench, a test speed of 50 mm / min tensile and standard type H2 specimens.From the tensile curves (stress = f (elongation)), obtained at a stretching speed of 50 mm / min, it is noted, for the composition tested, tensile modulus, elongation and tensile stress.

Measurement of melt volume melt flow rate (MVR) of the compositions: The volume melt index of the masterbatches was determined at 190 ° C. under a mass of 10 kg of the various samples using a Kayeness 4001 scale. Dynasco.

Measurement of the density: The density of the various samples of final thermoplastic composition is determined by weighing in the air (mass in the air) and in the water (mass in the water) of a standard specimen of the H2 type.

The density is calculated directly from the formula Mass in air d - (Mass in air - mass in water) Examples 1 to 6 demonstrate the benefits of the composition according to the invention: various thermoplastic compositions The final results, which differ only in the choice of the functional polyolefin used, are thus compared. The properties of the compositions of these examples are grouped together in Table 2. Table 2: Mechanical properties of the films obtained and MVR of the masterbatches Composition MVR Filmability Aspect of the film Grup Erup Traction module (MPa) (cm3 / 10min) (MPa) (%) (190 ° C / 10kg) Example 1 12 Very good Very good 12 260 110 Example 2 11 Very good Very good 12 310 110 Example 3 15 Very good Very good 10 330 110 Example 4 9 Very good Very good 12 310 100 Example 5 Very good Very good 14.2 Comparative Example 0.5 Good Good 12 110 100 It is found that the masterbatches according to the invention are more fluid than the comparative masterbatch. After mixing with the polyethylene, it is found that the filmability of the composition thus obtained is better and especially that the films according to the invention have a smooth appearance and without gels, unlike that formed with the comparative example.

Furthermore, the Applicant has observed a significant yellowing of the comparative masterbatch, related to a significant heating of the material during manufacture. Grafted polyolefin masterbatches do not have this disadvantage.

Claims (7)

Thermoplastic composition, useful as a masterbatch, said composition comprising: a thermoplastic starch consisting of at least one starch and at least one plasticizer of the starch; at least one polyolefin grafted with at least one functional compound bearing at least one polar function; and characterized in that the amount of thermoplastic starch is greater than 55% by weight, based on the total mass of the composition. 2 Composition according to the preceding claim, characterized in that the amount of thermoplastic starch is greater than or equal to 60% by weight, preferably greater than 65%, most preferably greater than 70%, relative to the total mass of the composition. 3 Composition according to one of the preceding claims, characterized in that it comprises, relative to its total mass, from 40 to 65% by weight of starch, preferably from 45 to 60%, more preferably from 45 to 55% . 4 Composition according to one of the preceding claims, characterized in that it comprises, relative to its total mass, 10 to 35% by weight of plasticizer, preferably 15 to 30%, more preferably 20 to 25%. Composition according to one of the preceding claims, characterized in that the plasticizer is chosen from glycerol, sorbitol, mannitol, maltitol, oligomers of these polyols, polyethylene glycol, urea or a mixture of these plasticizers. 6. Composition according to one of the preceding claims, characterized in that the grafted polyolefin comprises, relative to its total weight, from 0.1 to 5% by weight of functional compound, advantageously from 0.5 to 2% by weight. Composition according to one of the preceding claims, characterized in that the functional compound bearing the polar function is chosen from unsaturated carboxylic acid anhydrides, unsaturated carboxylic acids, unsaturated oxiranes and unsaturated silanes, preferably anhydride. maleic composition. 8. Composition according to one of the preceding claims, characterized in that it further comprises at least one polyethylene, preferably having a density of between 0.865 and 0.935. 9 Composition according to Claim 8, characterized in that it comprises, relative to its total mass: from 0 to 40% of polyethylene, for example from 0 to 25%, advantageously from 5 to 20%, better still at 20%, it being understood that the total of the constituents of the composition is equal to 100%. Composition according to any one of Claims 1 to 8, characterized in that it comprises between 0 and 20% of an optional constituent other than starch, the plasticizer of the starch, the functional polyolefin and the polyethylene which may be used. for example an additive, preferably between 0.1 and 5%, it being understood that the total of the constituents of the composition is equal to 100%. 11 Composition according to one of the preceding claims, characterized in that it has a melt flow rate index (MVR) (190 ° C, 10 kg) ranging from 1 to 50 cm3 / 10 min, advantageously from 2 to 30 cm3 / 10min, preferably from 5 to 20 cm3 / 10min. Composition according to one of the preceding claims, characterized in that the grafted polyolefin is chosen from: a functional polyolefin A which is at least one copolymer of propylene and at least one second alpha-olefin grafted with said functional compound this copolymer comprising, with respect to its total mass, from 45 to 95% by weight of units derived from propylene; a functional polyolefin B which is at least one functional polyolefin mixture comprising a polyethylene grafted with said functional compound and a polyethylene wax grafted with said functional compound; a functional polyolefin C which is a functional polyolefin which is a copolymer of ethylene; 35% of at least one ester (X) selected from vinyl esters of carboxylic acid and esters of (meth) acrylic acid; and optionally at least one additional monomer copolymerized with the ethylene and the ester (X); said copolymer being further grafted with said functional compound; and a functional polyolefin D which is a polypropylene grafted with said functional compound whose melt flow index is from 120 to 155 cm3 / 10 min (ASTM D 1238, 190 ° C., 2.16 kg). ). 13 Process for manufacturing a thermoplastic composition according to one of the preceding claims characterized in that it comprises at least one step of mixing in the molten or softened state of the various constituents and a step of recovering the thermoplastic composition. 14 Use of the composition according to one of claims 1 to 12 as a masterbatch. A process for producing a thermoplastic composition comprising a step of thermomechanically mixing the composition according to one of claims 1 to 12 with an additional polyethylene.