WO2002100919A1

WO2002100919A1 - Biodegradable thermoplastic linear copolymer, method for preparing same and uses thereof

Info

Publication number: WO2002100919A1
Application number: PCT/FR2002/001996
Authority: WO
Inventors: Henri Boccia; Isabelle Limousin; Christian Leriche; Li Nie; Cloudaldo Maningat; Sukh Bassi; Mrinal Bhattacharya; Mani RAMASWAMY
Original assignee: Midwest Grain Products, Inc.; University Of Minnesota
Priority date: 2001-06-11
Filing date: 2002-06-11
Publication date: 2002-12-19
Also published as: FR2825708A1; FR2825708B1

Abstract

The invention concerns biodegradable thermoplastic linear copolymers of the polyester type, obtained by polycondensation of saturated monomers of the diacid (a), diol (b) and or acid-alcohol type wherein are associated at least two other coupled monomers having functional -COOH and -OH groups capable of reacting with said functional groups (a), (b) and/or (c), and/or with each other, one of the added monomers (d) being provided with a tertiary carbon and the other added monomer (e) being an unsaturated acid anhydride. Said polyester-type thermoplastic linear copolymers are entirely biodegradable and can be used for producing articles such as, in particular, smart cards, electronic labels, impermeable films, toys, or they can be used as adhesives or printing inks.

Description

BIODEGRADABLE THERMOPLASTIC LINEAR COPOLYMER. PREPARATION PROCESS AND APPLICATIONS

Field of the Invention The invention relates to synthetic synthetic biodegradable thermoplastic copolymers.

More particularly, the invention relates to linear biodegradable thermoplastic copolymers of the polyester type, obtained by the polycondensation of saturated monomers of the diacid and diol types or of acid-alcohols to which two other types of monomers are added:

the first monomer being a hydrocarbon chain comprising at least one tertiary carbon, provided at its ends with pairs of reactive functions, such as (-COOH, -COOH) (-OH, -OH) or (-COOH, -

OH) ;

- the second being an unsaturated organic acid anhydride;

The invention also relates to the process for preparing the linear biodegradable thermoplastic copolymer.

The invention also relates to biodegradable polymer compositions produced from thermoplastic mixtures of linear biodegradable thermoplastic copolymers according to the invention with various natural biodegradable polymers such as carbohydrates, proteins or similar polymers.

State of the art Synthetic, thermoplastic or thermosetting polymers, produced using fossil molecules, in particular from natural petroleum, are increasingly used in numerous fields of application according to the desired physical, chemical and mechanical characteristics. by the user, by replacing other materials such as metals, wood, glass, natural fibers used in the field of textiles.

The massive use in all technical fields of polymer materials of synthetic origin poses a real problem of environmental protection when the objects in which these polymer materials actively participate reach the end of their life, as is the case as well for bulky objects such as a motor vehicle, as for objects of modest dimensions such as containers of food liquids (wine, oil) or other materials to be conditioned (liquid detergents, powder), housings of electric tools , or electronic equipment such as computers, both these objects, or the residues of polymer materials resulting from their destructive grinding, constitute real pollution for the environment. Because these various synthetic polymer materials are not biodegradable, can be photodegradable but, in the latter case, take a long time to degrade.

In the field of automobile construction, for example, there is a very high demand for synthetic polymer materials which intervene by creating new fields of operation or by replacing existing materials such as, for example, in the production bodywork elements (in ABS, in thermoplastic polyolefins for example), upholstery elements (seats in polyurethane foam covered with synthetic fabrics in polyamide, polyesters or similar), insulation of electric cables (for example thermoplastic elastomers) , sound insulation (carpets or non-woven fabrics) based on synthetic fibers, safety insulation (dashboards in soft polyvinyl chloride and polyurethane, polyamide airbag), optical design (polycarbonate), or d still others.

To overcome this pollution, an international research movement, both economic and scientific, is developing on the possible ways of recovering used synthetic polymer materials from end-of-life objects in which they have participated. One way is the use of these used polymer materials as fuel, for example in thermal power plants or cement / kilns. Another way consists in the reintroduction of used polymeric materials after they have been selected, treated and conditioned as recycled raw material, in the industrial circuits of production of objects by their substitution for virgin polymeric materials.

A third line of research and development concerns the development of biodegradable polymeric materials which should replace, whenever possible, non-biodegradable synthetic polymeric materials, in objects, in particular of convenience or of high development, such as, for example, the smart card. This third way results from the numerous observations that:

- the use of synthetic, non-biodegradable polymer materials continues to grow while the reserves of fossil molecules are ultimately limited;

- the environment can no longer be polluted by landfills of residues of non-biodegradable synthetic polymer materials when the objects produced, in whole or in part, using these synthetic polymer materials reach the end of their life.

This is why, the state of the art conceals numerous documents which describe polymers, copolymers considered to be biodegradable, and / or compositions combining them with natural polymers themselves biodegradable, such as starch, and each having , in a more or less pronounced manner, the desired character of biodegradability.

These polymers and copolymers considered to be biodegradable are generally used in compositions combining them with natural biodegradable polymers, compositions which may also contain other components such as non-biodegradable synthetic thermoplastic polymers and / or copolymers, plasticizers, crosslinking agents, and other agents conventionally used in polymer compositions such as, for example, anti-UV agents, flame retardants, mineral fillers.

Several types of biodegradable synthetic polymers and copolymers and / or compositions containing them are described in the prior art.

According to a first type of biodegradable compositions, which manifests itself as a mixture of a biodegradable polymer and a synthetic copolymer | a polymer composition (WO91-02025) is proposed for the production of articles considered to be biodegradable, production carried out according to plastics processing techniques comprising, in mixture, destructured biodegradable starch, a synthetic copolymer chosen from the group formed by ethylene vinyl acetate, ethylene glycidil acrylate, ethylene maleic anhydride, ethylene vinyl alcohol, a plasticizer selected from the group consisting, for example, of glycerin, ethylene glycol, propylene glycol , polyethylene glycol, a crosslinking agent such as, for example, formaldehyde, epichlorhyrin, as well as other additive agents conventionally used. but such a composition is only biodegradable through the natural polymer and, therefore, can only be considered partially biodegradable, the synthetic copolymer of the composition not being, but being rather sensitive to UV degradation . Consequently, the degradation of such a composition can only be complete in the long term.

According to another type, a biodegradable thermoplastic composition (WO98 / 40434) is formed from a mixture comprising a polymer which can be considered to be biodegradable, obtained by polycondensation of an alcohol acid which is lactic acid and a thermoplastic resin it - Even formed by a mixture of synthetic thermoplastic polymer and / or copolymer, of a natural polymer which is destructured starch, a plasticizer, a crosslinking agent and other agents conventionally used in polymer compositions.

Among the polymers and / or copolymers entering into the mixture forming the thermoplastic resin, are preferably retained polyethylene, polyvinyl alcohol, polyacrylonitrile, copolymers resulting from the copolymerization of an olefinic monomer selected from ethylene, propylene, isobutene, styrene, with another monomer selected from the group of acrylic acid, vinyl alcohol and / or vinyl acetate.

As for the plasticizing agent used in the resin, it is preferably chosen from polyalcohols, their derivatives, such as glycerin, ethylene glycol, polyethylene glycol.

The crosslinking agent contained in the resin is chosen from those usually used, such as aldehydes, ketones, glyoxals, epoxies or others. .

Such a composition, which contains a synthetic polymer ¹ , is not completely biodegradable. In addition, this composition offers fairly low mechanical and thermal properties since it has poor impact resistance and a glass transition of less than 80 ° C.

In the same spirit as the previous document, a biodegradable thermoplastic composition intended for the production of bank cards (JP2000-309695) has been proposed which comprises, in particular, a copolymer of lactic or polylactic acid and a hydroxy-carboxylic acid . Another biodegradable thermoplastic composition for the production of articles (US Pat. No. 5,658,627) consists of a mixture of two biodegradable aliphatic polyesters, the first of which is obtained by reaction between a polyesterdiol with a diisocyanate, the polyesterdiol resulting from the polycondensation of a mixture of succinic and adipic acids with a glycol, while the second is obtained by reaction between a polyesterdiol with a diisocyanate, the second polyesterdiol resulting from the polycondensation of succinic acid with butane diol (comments on the disadvantages, in particular the implemented).

This biodegradable thermoplastic composition is intended to be used in fields such as, for example, packaging with a relatively short period of use, barrier films, biomedical, agriculture, should be biodegradable so that, after use, they are degraded in an appropriate physiological environment by biodegradation actions.

Despite the intrinsic qualities developed by these so-called biodegradable polymers, copolymers and / or compositions containing them in combination with natural polymers, themselves biodegradable, such as destructured starch, troublesome phenomena occur which are summarized below and which relate to one or other of the polymers, copolymers and / or biodegradable compositions previously mentioned in the prior art.

The related phenomena can be mentioned:

- the presence of conventional thermoplastic polymers and / or copolymers in compositions containing them in combination with biodegradable polymers, leads to? partial biodegradability, said polymers and copolymers / conventional degrading only very slowly by photodegradation;

- the low mechanical and thermal properties of polymers, biodegradable copolymers and biodegradable compositions resulting therefrom, due to low impact resistance;

- a significant reduction in the biodegradability of polymers or copolymers of the thermoplastic polyester type, as soon as their molecular weight tends to be high or even that their state of crystallinity increases; - the virtual disappearance of the biodegradability of polymers, copolymers of the unsaturated thermoplastic polyester type, when the presence, in their molecular structure, of the presence of b = C double bonds develops which subsequently develop uncontrolled crosslinking.

Finally, according to another type of biodegradable copolymers obtained by synthesis, and / or of compositions containing said copolymers in combination with natural biodegradable polymers, copolymers of aliphatic linear saturated polyester type have been proposed (WO-0077069). These copolymers are composed of at least two monomers, one of which is a dicarboxylic acid comprising a tertiary carbon, the most representative type of which is citric acid, and the other is a dialcohol, such as butane diol. ^* '

Such biodegradable copolymers offer major advantages which make them interesting. These copolymers, in fact:

- are 100% biodegradable;

- have pendant -OH and -COOH groups in the molecular structure which make it possible to create ionic and / or hydrogen bonds from molecule to molecule;

- allow the pendant -COOH groups to create, via bivalent or more ions and / or their oxides, reinforced thermoplastic structures, which are very sensitive to thermodegradability, promoting subsequent biodegradation;

- give the properties of thermoplastic networks that are more or less physically crosslinked thanks to the presence of '' tertiary carbon having pendant acid groups. î

Besides these multiple major interests, these copolymers of biodegradable polyester type have troublesome drawbacks which affect the ability of said copolymers to have sufficient biodegradability.

Among these disadvantages, may be indicated, by way of example: "

the polyester type polycondensation copolymerization which takes place at an already relatively high temperature, in the presence of a catalyst, by causing effects as diverse as anhydrization between two tertiary groups each carrying -COOH functions, dehydration between also two tertiary groups carrying one of a -COOH function and the other of an -OH function, or dehydration between an —OH group and a —CH ₂ group, giving a double bond group C = C, this copolymerization leading to the production of troublesome molecules having the property of hampering, at least in part, the total biodegradability said copolymers;

- the eminently random and uncontrollable crosslinking of said copolymers, depending on whether intermolecular bonds of ionic or hydrogen type occur, or whether the creation of a double or double bond group jC ^ is manifested by a secondary dehydration effect , causing uncertainty about the crosslinking rate of said copolymers and their capacity, according to this rate to be still biodegradable.

Thus, the previously mentioned findings have generated a demand and a need for biodegradable polymer materials, a large number of which use, at least in part, sources of renewable, biodegradable natural polymer materials, as opposed to conventional synthetic polymer materials generally very resistant to attack. microbiological agents.

Summary of the invention

According to the various objects of the invention previously stated, the linear biodegradable thermoplastic copolymers of the polyester type eliminate the drawbacks manifested in the examination of the state of the art and bring, in addition, substantial improvements, which do not exist in the means described. to date, to make these biodegradable copolymers particularly attractive in the production of articles intended for biodegradation after use.

According to the invention, the linear biodegradable thermoplastic copolymers of the polyester type, obtained by polycondensation of saturated monomers of general formulas: (a) of the diacid type HO-CO-D-CO-OH,

(b) of HO-E-OH diol type,

(c) and / or of the acid-alcohol type HO-F-COOH,

in which D, E, F are saturated hydrocarbon chains are characterized in that these monomers of type (a), (b) and / or (c) are associated with at least two other coupled monomers having functional groups -COOH and -OH capable of reacting with the functional groups of said monomers of type (a), (b) and / or (c), and / or between them,

(d) the first coupled monomer provided with a tertiary carbon corresponding to the general formula: \

in which :

- m> 1

- the couple Yi, Y ₂ of the tertiary carbon is of the type (-COOH, -OH) (- COOH, Ri), (-OH-Ri) where Ri is H or a hydrocarbon chain

- Xi and X ₂ , placed at the ends of said monomer, are chosen from the group consisting of two by two combinations of the acid and alcohol reactive functions, giving Xι = X ₂ = -COOH or Xι = X ₂ = -OH or Xι = -COOH and X ₂ = -OH

A and B are each linear aliphatic hydrocarbon chains which may be branched, comprising at least one of the hydrocarbon groups chosen from the group consisting of:

where n> 0, p> 0, q> 0, and where R ₂ , R3 and R ₄ are chosen from the group consisting of reactive functions, -COOH, -OH or aliphatic hydrocarbon chains of type - (CH ₂ ) _r CH ₃ with r> 0.

(e) the second coupled monomer being an acid anhydride with double bond C = C corresponding to the general formula:

in which R ₅ and Rβ are chosen from the group consisting of hydrogen -H, aliphatic hydrocarbon chains, branched or not, of the type - (CH ₂ ) _r CH ₃ with r> 0.

Detailed description of the invention

The degradable copolymers according to the invention

Linear biodegradable thermoplastic copolymers of the polyester type containing, in their molecular structure, tertiary carbons with which pendant functional groups -COOH and / or -OH are associated, may be the cause of side reactions during polycondensation by esterification, giving bothersome byproducts. It has been found that in order to control, or even prevent, these side reactions, of organic acid, having

implemented with the other comonomers that are organic diacids of type (a), diols of type (b) and / or acid-alcohols of type (c). The acidic comonomer of type e) organic acid anhydride having an ethylene double bond C = C has a reactivity equivalent to the reactivity of the primary acid groups of the diacid monomers and, in particular, of the monomer provided with a tertiary carbon of type (d) when it is acid, involved in the composition of the copolymers according to the invention.

I- ¹ 1 It follows from the implementation with the other monomers (a), (b) and / or (c), therefore of the monomer of type (d) coupled with the monomer of type (e) anhydride of organic acid having in its structure an ethylenic _/ C≈ double bond, that the conditions for producing the copolymers according to the invention are much milder than in the absence of said comonomer (e), this copolymerization being carried out in the absence of catalyst, at a lower temperature and with a much higher reaction kinetics. Consequently, the linear biodegradable thermoplastic copolymers of the polyester type according to the invention containing, in their structure, saturated monomers of diacid and diol, or acid-alcohol types, to which are added the pair of monomers of type (d) and of type (e), the latter being an unsaturated organic acid anhydride, differ from the state of the art by a large number of characteristics, some of which are particularly remarkable, which are discussed below.

One of the first characteristics of the copolymers according to the invention is that they are completely biodegradable as are natural polymers such as starch and that, used alone or in admixture with natural biodegradable polymers in a thermσplastic composition, therefore that objects are produced with these copolymers and / or compositions containing them, these objects are themselves completely biodegradable and are actually biodegraded without leaving residues, usually present when non-biodegradable synthetic polymers and / or copolymers are used such as polyolefins mixed with natural biodegradable polymers.

The total biodegradability of the copolymers and / or of the compositions according to the invention is also acquired when the linear biodegradable thermoplastic copolymers of the polyesters type according to the invention are also used for the production of articles by the techniques of thermoplastic plastics and that said articles are crosslinked and go from a thermoplastic to a thermoset state.

Another characteristic of the copolymers according to the invention is that these copolymers are obtained by copolymerization at moderate temperatures, in the absence of catalyst and over a short period with excellent kinetics of copolymerization and very good control of the molar masses thanks the presence of a comonomer of the organic acid anhydride type. These particularly mild copolymerization conditions result in an absence of side reactions during the polymerization such as:

anhydrization between two tertiary groups, each carrying -COOH functions; or else dehydration between two tertiary groups, one carrying a -COOH function and the other of an -OH function; - Or dehydration between an -OH group and a -CH ₂ group, giving a group with an ethylenic double bond _/ C≈G ^

Another remarkable characteristic of the copolymers according to the invention lies in the fact that these copolymers have several tertiary carbons provided with pendant functional groups -COOH and / or -OH, distributed throughout the molecule. The functional groups -COOH of tertiary carbon which do not take part in the polycondensation reaction by esterification during the copolymerization, can however play an important role in the modification of the physical properties of the copolymers by the formation of intermolecular bonds of ionic type or hydrogen, these bonds having the capacity to create structures in intermolecular networks.

In the case of an intermolecular bond of the ionic type, the —COOH acid groups of the tertiary carbons present in the molecules of the copolymers according to the invention can react with multivalent ions M ^{R +} , in which R can take values ranging from 2 to 4, for example Ca ⁺⁺ , Mg ⁺⁺ , Zn ⁺⁺ , Al ⁺⁺⁺ , Si ⁴⁺ , Ti ⁴⁺ , by creating an ionic structure of the type, for example, with a bivalent ion:

giving

-CC-Cf ... M ²⁺ ... ^" OCC-

I II II I

O 0

It is the same in the case where the acid groups / -pθOH of the tertiary carbons of the molecules of the corresponding monomers are placed in the presence of metal oxide such as, for example, MgO, CaΘ, ZnO, AI ₂ θ ₃ , TiO ₂ , Si0 ₂ , during the polymerization of the copolymer according to the invention, these acid functional groups of tertiary carbons creating with said oxide, structures in intermolecular networks.

In the case of an intermolecular bond of the hydrogen type, the acid groups -COOH and hydroxyls -OH of the tertiary carbons present in the molecules of the copolymers according to the invention can create an intermolecular network structure of the type: - acid

I I

-C-C-OH ... HO-C-C-

I II II I

0 0

- hydroxyl

- hydroxy acid

I I

-C-C-OH ... HO-C-

I II I 0

These ionic or hydrogen bonds are formed between the copolymer molecules according to the invention by creating an intermolecular network structure and lead on the one hand to the reinforcement of the thermoplastic character of the copolymer according to the invention and, on the other hand, to a cleavage. improved reversible thermal, that is to say a rupture of the ionic bonds by physico-chemical transformation when this type of structure is subjected to strong rise in temperature, the copolymers being, consequently, thermoreversible.

These ionic or hydrogen bonds present in the copolymers according to the invention are known to be much more sensitive to biodegradation and to have kinetics of biodegradation due to the fact that their greater sensitivity to water is infinitely faster than that of covalent bonds. or homopolar present in polymers and / or copolymers of conventional synthesis such as, for example, polyolefins, polyamides, polyesters, cited in the prior art, polyurethanes.

Another characteristic of the copolymers according to the invention is the presence, in a controlled amount, as a comonomer, of the organic acid anhydride having a double bond C = C in its molecule. Although this double bond present in the copolymers according to the invention does not intervene during the copolymerization, it subsequently allows a controlled crosslinking of said copolymers which, from thermoplastics, become thermosets by crosslinking without their complete biodegradability characteristic being compromised. . In other words, and according to the invention, the quantity of comonomers e) which is an organic acid anhydride, provided in its structure with a double bond, is such that, during the copolymerization of the monomers and the use of the copolymers according to the invention:

- anhydrization and dehydration reactions do not occur;

- ionic or hydrogen bonds can occur;

\ /

- crosslinking by the double bonds ^ = 0 _^ present takes place fully;

- the biodegradability remains intact and is not compromised by the crosslinking of the double bonds ^ ç

According to the invention, the first monomer corresponds to the general formula:

In this general formula, where m> 1, m can be between 1 and 4 but is preferably equal to 1.

The groups Yi and Y ₂ attached to tertiary carbon, and of which at least one is a functional group, the pair Yι-Y ₂ , can be (-COOH, -OH) or (-COOH, -R1) or (- OH, Ri), Ri being able to be hydrogen or a Ci to Cι ₈ hydrocarbon chain and preferably hydrogen or a Ci to Cs hydrocarbon chain.

The groups Xi and X ₂ are reactive functional groups chosen from the reactive functions -COOH and -OH which form a diacid, a dialcohol or an alcohol acid. /,

The groups A and B are each linear aliphatic hydrocarbon chains, optionally branched, comprising at least one of the hydrpcarbonic groups chosen from the group consisting of:

hydrocarbon groups in which - n> 0, can take a value between 1 and 5, preferably equal to 1;

- p> 0, can take a value between 1 and 5; - q> 0, can take a value between 1 and 5;

- R ₂ , R ₃ and R are chosen from the group consisting of reactive functions, -COOH, -OH, and aliphatic hydrocarbon chains of the type - (CH ₂ ) r-CH ₃ with r> 0, which can take a value between

1 and 5.

All the monomers corresponding to the above general formula are obtained by organic synthesis, one of them preferably being citric acid.

The second monomer according to the invention corresponds to the general formula:

This monomer is an organic acid anhydride having, in its structure, a double bond C = Ç, the R ₅ and R ₆ can be chosen from the group consisting of hydrogen, aliphatic hydrocarbon chains branched or not, of the type - (CH ₂ ) _r -CH ₃ where r> 0, and can be chosen between 1 and 5.

Among the organic acid anhydrides corresponding to the above general formula, may preferably be retained maleic anhydride, itaconic anhydride, citracptyque anhydride, tetrahydrophthalic anhydride 3, 4, 5, 6.

The other monomers according to the invention correspond to the general formulas:

HO-CO-D-CO-OH of the diacid type,

HO-E-OH of the diol type, and / or HO-F-COOH of the acid-alcohol type, in which D, E and F are linear, optionally branched, aliphatic hydrocarbon chains comprising at least one of groups such as:

or :

- S> 1 and preferably between 1 and 8

- T> 1 and can take a value between 1 and 5,

- U> 1 and can take a value between 1 "and 5,

- R ₂ , R ₃ , R ₄ being chosen from the group consisting of the reactive functions -COOH, -OH and the aliphatic hydrocarbon chains of the type (-CH ₂ ) r-CH ₃ or r> 0, can take a value included between 1 and 5.

Depending on whether the monomer of type (d) is a diacid, a dialcohol or an acid-alcohol, the monomers of type (a), (b) and / or (c) according to the invention will be chosen such that the reaction polycondensation between the total of -COOH functions and the total of -OH functions occurs stoichiometrically.

According to the invention, the monomer of type (a) is a diacid such as, for example, succinic acid, sebacic acid, phthalic, isophthalic, terephthalic acid, malonic acid, adipic acid, diglycolic acid, glutaric acid.

According to the invention, the monomer of type (b) is a dialcohol such as, for example, ethylene glycol, diethylene glycol, propylene glycol and dipropylene glycol, propane diol, butane diols 1-2, 1-3 , 1-4, ^ 3, pentane diols 1-5 and 1-6, hexanediol.

According to the invention, the monomer of type (c) is an acid-alcohol such as, for example, lactic acid, glycolic acid, hydroxypropanoic acid, hydroxybutanoic acid, acid hydroxy-pentanoic acid.

said copolymers allow their subsequent crosslinking by passing them from a thermoplastic state to a thermoset state. However, it is obvious that a high crosslinking rate of a copolymer weakens its capacity for biodegradability. This is why a balance has been found to simultaneously ensure the copolymers according to the invention both very good biodegradability and a sufficient crosslinking rate of between 1% and 20% by mole of the monomer (e) per chain affected by crosslinking

The relative amounts of the first monomer of type (d) having a tertiary carbon which is a diacid, a diol or an acid-alcohol and the second

bond = Q ^ which are involved in a coupled mixture in the polycondensation reaction by esterification, vary relative to each other in industrial use from 1% to 99% by moles and, preferably, from 1% to 60% by moles equivalent of acid functions for organic anhydride of type (e) and from 99% to 1% in moles of equivalent of acid functions, and preferably from 99% to 40% for the acid and / or acid-alcohol monomers of type (d).

The relative amounts of the monomer of type (d) provided with a tertiary carbon vary in industrial use between 1% by mole and 30% by mole and, preferably, between 1% by mole and 20% by mole of the total of all the monomers present in the composition carrying the same type of reactive functions.

The relative amounts of the monomer of type (e), which has an unsaturated organic acid anhydride which intervenes in coupled coupling with the monomer of type (d) in the polycondensation reaction by esterification are chosen in industrial use between 1% by mole and 30% by mole and, preferably, between 1% by mole and 20% by mole of the total of all the monomers present in the composition carrying the same type of reactive functions.

Consequently, the relative amounts of the monomer of type (a), which is an organic diacid, are chosen so as to balance the stoichiometry of the ratio [-OH] / [- COOH) by reference to the -OH present by excluding the -OH pendants of the tertiary carbons present in the monomer of type (d) and of the alcoholic acids of the monomer of type (c) whose functions -COOH and -OH exactly balance.

The relative amounts of the monomer of type (b), which is a diol, are also chosen so as to balance the stoichiometry of the ratio [-OH] with reference to the -COOH present, excluding the pendant -COOH [-COOH] of the tertiary carbons present in the monomer of type (d) and of the alcohol acids of the monomer of type (c) whose functions -COOH and -OH are balanced exactly.

Consequently, and according to the relative quantities of the acid monomers, diols and / or acid-alcohol, and of the monomer provided with a tertiary carbon of type (d) and anhydride of unsaturated organic acid of type (e) as stated , the copolymers according to the invention retain all their advantages and more particularly:

- have the thermoplastic character for the transformation step and are crosslinked after transformation by assuming at least partially a thermoset character while retaining their biodegradability characteristic;

- cannot be the site of excessive crosslinking reactions, due to the control of the quantity of double bonds ^ ≈C ^ present in the mass of said copolymer;

- retain all their potential for compatibility with regard to other natural or synthetic polymer materials and, therefore, all their adhesion capacity;

- benefit, in the case of the use of low molar masses, such as oligomers, of a real increase in their properties and in their resistance to solvents;

- have great potential to be used, in the presence of mineral fillers, pigments.

- have the capacity to integrate into their compositions other unsaturated monomers or oligomers such as having a double bond

ability to adhere and to increase chain lengths in intermolecular bonds.

As for the relative amounts of the alcohol monomers compared to the acid monomers and unsaturated organic acid anhydride, necessary for polycondensation by esterification of said monomers according to the invention, they are expressed by the ratio of the total of the reactive functional groups -OH and -COOH, excluding the pendant -OH and -COOH linked to tertiary carbons, and to acids- alcohols present, so that this ratio is between the values:

[ -OH]

0, 95 <<1, 05

[-COOH]

this ratio being extremely close to stoichiometry, the small variations in said ratios making it possible to play a little with the molar masses of the copolymer according to the invention and, in particular, on the Melt Index of said copolymer.

Process for obtaining the copolymers according to the invention The polyester copolymers according to the invention are obtained by polycondensation resulting from the interaction of organic diacids (a), dialcohols (b) and / or acid-alcohol (c ) coupled of type (d) provided with a tertiary carbon and in the presence of the monomers of type (e) which is an organic acid anhydride provided with a double bond X ^ and which has, because of this double bond, an unsaturated character.

The polycondensation of the monomers (a), (b) and / or (c), (d) and (e) is carried out in a reactor of known type and more particularly in a thin-film reactor, in the absence of catalyst and at a temperature between 110 ° C and 170 ° C, with elimination "in situ" of the gaseous phases such as water formed.

In particular, the polycondensation can be carried out in an extruder under the temperatures mentioned, and can also be carried out in the presence of a natural polymer such as, for example, starch associated or not with gluten, one and the other being known for their biodegradable nature and being used as co-constituents of said copolymers according to the invention to increase the synergy of biodegradation.

In general, the polymerization process comprises all the successive stages, which are the supply of monomers in the appropriate respective quantities, their kneading, the elimination of the gaseous phases. generated by the reaction, in particular the aqueous phase eliminated in the form of water vapor and, optionally, the introduction of other components such as natural biodegradable polymers, antioxidant agents, such as known phenolic compounds, for example, Irganox 1010 and 1076, sold by the company CIBA-GEIGY, necessary for the protection of the double bond during processing, plasticizers, mineral fillers, and various other agents such as, for example, dyes, retarders of flame, the last step being that of extrusion and cutting of the extruded material, giving granules of copolymers alone or comprising the other components mentioned above. All these agents are introduced into the medium receiving them in adequate amounts well known to those skilled in the art. ?

The physicochemical characteristics of the copolymers according to the invention can be conditioned by the choice of the monomers within the groups of types of monomers (a), (b) and / or (c), (d) and (e) , their relative amounts, the rate of ionic and / or hydrogen bonding.

In the case of an ionic bond which occurs through the use of ions or their oxides, it is possible to substantially improve the mechanical properties of the copolymers according to the invention, by varying within the limits previously mentioned the amount of monomer having tertiary carbons having pendant groups -COOH. In general, the rate of ions and / or their oxides is determined by the rate of pendant -COOH groups, while taking into account the rate of hydrogen bonds used.

The relationship between [pendant COOH] / [ions and / or oxides] is close to stoichiometry, that is to say evolving between the limits of Q, 95 and 1.05.

Thus, the properties of flexural rigidity or of biodegradability which are sought as a function of the uses of the copolymers according to the invention can be achieved by means of the simultaneous adjustment of the rate of pendant -COOH groups of the tertiary carbons present and of the rate of ions and / or their oxides used during the polymerization.

The copolymers according to the invention can have a molecular mass of between 500 and 100,000 and, preferably, between 2,000 and 30,000. Biodegradable polymer compositions

The invention also relates to biodegradable polymer compositions formed from at least one of the linear biodegradable thermoplastic copolymers of the unsaturated polyester type according to the invention and from at least one natural biodegradable polymer in combination or not with at least one of the various agents mentioned which can accompany the copolymers of the invention.

Also according to the invention, completely biodegradable polymer compositions are formed:

from 30% to 100% and, preferably, from 50% to 90% by weight of linear biodegradable thermoplastic copolymers of the polyester type according to the invention, and

- from 70% to 0% and, preferably, from 50% to 10% by weight of at least one natural polymer.

The natural biodegradable polymers which are capable of being combined with the copolymers according to the invention by giving, once combined, completely biodegradable compositions, can be chosen from carbohydrates such as polysaccharides and, among them, starch, cellulose, for example wood powder, cellulose fibers, proteins, and, in particular, nucleic acids, amino acids such as those present in gluten, and lipids which are all biodegradable polymers.

These natural biodegradable polymers can be used in combination with the copolymers according to the invention, reason for at least one of them, that is to say that these natural biodegradable polymers can be used alone or in combination with them. a mixture of several of them with said copolymers according to the invention.

Among the carbohydrates desirably used in the composition according to the invention, there are cited the polysaccharides which are widely present in the plant or animal world, and more particularly starch, gluten and cellulose.

Starch, which is the most favorably retained polysaccharide in the context of the invention, can produce sugars by hydrolysis. Starch can include a mixture of linear (amylose) or branched (amylopectin) components of very variable molecular weights: approximately 100,000 for amylose and one million for amylopectin: the starch used in the context of the invention can therefore be a mixture of amylose and amylopectin in an amount of 0 to 100% by weight of amylose and from 100% to 0% of amylopectin.

Any type of starch can be used in the context of the invention, including, in particular, substituted, chemically modified, crosslinked and unmodified starches.

The natural biodegradable polymer proteins can also be used in combination with the copolymers according to the invention to form biodegradable polymer compositions also subject of the invention: they can be chosen from the group consisting of animal or vegetable proteins such as, for example, example, eggs and / or milk and / or cereals.

Lipids, natural biodegradable polymers, can also be used in combination with the copolymers according to the invention to form biodegradable polymer compositions also subject of the invention. These lipids are known to be natural combinations of glycerol and fatty acids. From animal or plant sources, the lipids preferably used in the context of the invention are oils of vegetable origin, in particular grain oils.

According to the invention also, the compositions resulting from the combination of natural polymers as they were previously mentioned, with the copolymers according to the invention, can also contain in combination at least one ion chosen from the group preferably constituted by Ca ^{2 +} , Mg ²⁺ , Zn ²⁺ , Al ³⁺ , Si ⁴⁺ , Ti ⁴⁺ and / or at least one oxide / chosen from. group preferably constituted by CaO, MgO, ZnO, AI ₂ .O ₃ , SiO ₂ , TiO ₂ . The addition of these compounds (ions and / or oxides) allow the creation of ionic bonds between the various molecules of the copolymers according to the invention by reinforcing the structure of said polymers by creation of an intermolecular network which can be three-dimensional. These ionic bonds, known to be sensitive to hydrolysis phenomena, can ensure the rupture of the intermolecular network and thus facilitate the biodegradation of the polyester copolymers according to the invention by release of their molecules. The compositions according to the invention defined as those formed by the copolymers according to the invention and at least one biodegradable natural polymer, can also contain other polymeric materials such as, for example, polyvinyl alcohols, ethylene copolymers and vinyl alcohol, polyamides, polyurethanes, polyacrylics, polycarbonates, alone or as a mixture, in small amounts, such as from 1 part by weight to 25 parts by weight per 100 parts by weight of the copolymers according to the invention or compositions according to the invention in order not to reduce the capacity of the copolymers and compositions according to the invention to be biodegraded.

The compositions according to the invention may finally contain various agents usually used in polymer compositions such as, for example, dyes, pigments, mineral fillers such as, for example, CaCO ₃ , antioxidants, anti-ultraviolet or others, implemented in well known quantities.

According to the invention also, and according to what has been mentioned previously, the copolymers according to the invention, which are thermoplastic copolymers, formed by means of the monomers of type (a), (b) and / or (c), ( d) and (e) one of which, type (e), is an anhydride of an unsaturated organic diacid, that is to say containing a double bond ^ ≈C ^ can be transformed under the influence d 'a catalyst, in thermoset copolymers by the opening of the double bonds of the organic acid anhydride by forming a three-dimensional network by crosslinking.

This crosslinking can be done cold or hot, chemically, in the presence or absence of an appropriate catalyst, or even by irradiation such as ultraviolet, infrared or electronic. ,

The most widely used catalytic systems can be chosen from the group consisting of methyl ethyl ketone peroxide associated with a cobalt salt such as cobalt octoate or naphthenate, benzoyl peroxide alone or associated with a tertiary amine, cumene hydroperoxide, methyl isobutyl ketone hydroperoxide, lauryl peroxide, cyclohexanone peroxide, dicumyl peroxide or others.

The introduction of the catalytic systems into the copolymers according to the invention or the compositions containing said copolymers associated with natural polymers can be carried out in known kneaders and more particularly in an extruder, this introduction taking place at a temperature below that of their decomposition.

\ / This opening of the double bonds ^ ≈Ç ^ which constitutes a crosslinking can be carried out cold or hot depending on the catalyst used, without gassing, and desirably during the extrusion operation of the only copolymers according to the invention or compositions combining said copolymers with natural biodegradable polymers.

The biodegradable polymer compositions according to the invention can be obtained in particular by a process of preparation in stages, which is carried out in a thin-film reactor. "

In a first step, the polycondensation of the monomers of types (a), (b), (c), (d) and (e) is carried out, in the absence of any polycondensation catalyst, the reaction medium being placed under a temperature included, and capable of changing, from 110 ° C. to 170 ° C. for the time necessary for the polycondensation, the aqueous phases resulting from the condensation reaction being eliminated progressively.

In a second step, at least one biodegradable natural polymer and / or at least one ion chosen from the group consisting of Ca ²⁺ , Mg ²⁺ , Zn ² is introduced into the thin-film reactor within the copolymer formed. ⁺ , Al ³⁺ , Si ⁴⁺ , Ti ⁴⁺ and / or at least one oxide of one of these ions, as well as, optionally, various agents of known type, the reaction medium being maintained at a temperature not exceeding not 170 ° C., then the mixture thus produced is extruded and the extruded mixture is granulated.

The copolymers and / or the compositions according to the invention find an excellent application, according to their molar weights, and - by adjusting their formulations, in fields as diverse as the production of articles by injection, extrusion, molding, lamination, such as contact and / or contactless smart cards, electronic labels, waterproof films, toys, or even be used as adhesive, printing inks.

The invention will be better understood thanks to an illustration made by means of nonlimiting examples. Example 1: State of the art

This example relates to the production of a linear biodegradable thermoplastic copolymer, of the polyester type, belonging to the state of the art.

The composition of this copolymer is as follows:

- citric acid: 1.5 moles - ethylene glycol: 1.5 moles

The stoichiometric ratio between citric acid (diaςide) and ethylene glycol (diol) is [COOH] / [OH] = 1.

The mixture of the two initial compounds also comprising an antioxidant agent (0.05% of Irganox 1010) is introduced into an appropriate reactor and brought gradually to the temperature of 180 ° C.

At the end of the polycondensation reaction, which lasts three hours, the polyester obtained is subjected to a vacuum operation to remove the water formed during the polycondensation reaction.

The presence of citric acid leads to very strong crosslinking by hydrogen bonds, very sensitive to a rise in temperature.

The copolymer thus obtained is difficult to use by the methods of plastics processing as the operating conditions are particularly sharp.

Example 2: State of the art r,

This example also relates to the production of a linear biodegradable thermoplastic copolymer, of the polyester type, belonging to the state of the art.

The composition of this copolymer is as follows

- succinic acid: 0.50 mole

- butane-diol: 0.50 mole - catalyst: Ti (OBu) ₄ 0.15 mole% The diacid / diol stoichiometric ratio, that is to say [total COOH] / [total OH] is 1.

As in Example 1, the mixture comprising 0.50 mole of succinic acid, 0.60 mole of ethylene glycol and 0.15 mole% of catalyst Ti (OBu) ₄ , to which an antioxidant agent is added (0 , 05% Irganox 1010), is introduced into an appropriate reactor and gradually brought to the temperature of 200 ° C. The complete reaction time for polycondensation between the various monomers was of the order of three hours.

The polycondensation reaction is carried out in such a way that the polymer obtained is freed from the water formed during the reaction.

The copolymer obtained after this vacuum operation is a homogeneous solid compound.

The final product solidifies over time in the form of a homogeneous solid compound, whitish in color and the melting point of which measured by differential enthalpy analysis is approximately 109-110 ° C with a shoulder at approximately 105 ° C.

The product is soluble at 3% in hexafluoroisopropanol (HFIP) and remains in the form of blocks in dissolution in acetone in a proportion of 50/50.

Only the low molar masses appear to be soluble in THF.

The melting point of the copolymer was found to be between 108 ° C and 115 ° C.

The product resulting from this example presents an itrous transition of rupture of hydrogen bonds not, or hardly visible: the copolymers thus obtained do not have sufficient mechanical properties so that they can be used in applications developed by the plastics industry .

Example 3 (according to the invention)

This example relates to the production of a linear biodegradable thermoplastic copolymer, of the polyester type, according to the invention.

The composition of this copolymer is as follows: - succinic acid: 0.7 mole

- citric acid: 0.15 mole

- maleic anhydride 0.15 mole

- butane-diol: 1 mole

- antioxidant: IRGANOX 1076 marketed by CIBA-

Geigy

The stoichiometric ratio between citric acid and maleic anhydride (diacid): (-COOH) / (- COOH) is equal to 1.

The stoichiometric ratio between the diacid and the diol: (-COOH total) / (- OH total) is also equal to 1.

The ratio in mole% between maleic anhydride and succinic acid is 21.4%.

The ratio in mole% between maleic anhydride and the total of the acid functions provided by succinic acid and citric acid is 17.6% by mole.

The mixture of maleic anhydride and succinic acid compounds containing the antioxidant IRGANOX 1076 is introduced into an appropriate reactor, heated around 120 ° C. The citric acid is then introduced into said reactor. The temperature of the acid mixture is then brought to 130 ° C. As soon as this temperature level is reached, the butane diol is in turn introduced while the temperature is brought to 160 ° C.

The polycondensation reaction is carried out for a time of approximately three hours, during which time a gradual increase in the viscosity of the reaction medium is observed. A sample of the polymer was extracted from the medium after three hours.

The copolymer obtained at this stage is completely soluble in THE. Its average molar mass n, measured by the GPC method, has been found to be approximately 10,000, with maximum values of approximately 22,000.

FIG. 1 represents the infrared spectrum of this copolymer according to the invention, which reveals the presence of ester groups and double bonds, all the corresponding numerical data being gathered in Tables 1 and 2 below, each table being specific to a particular peak. Table 1 Pic No. 1

MN = 21074 MW = 25264

Table 2 Pic No. 2

MN = 2442 MW = 4441

Consequently, an introduction of 32.4 g of starch was carried out within the copolymer obtained. The temperature of the mixture was maintained at 160 ° C for one hour. At the end of this time, a slightly yellowish product was collected, constituting the composition according to the invention.

The composition thus obtained by mixing the copolymer according to the invention and the starch is then placed in THF where it is only partially soluble therein.

The soluble part is a starch grafted with the copolymer according to the invention.

The molar masses are of the order of 25,000 on average, with some maximum values observed of the order of 128,000 and 1,450,000. The peaks probably correspond to a grafting of the starch by the polyester copolymer, accompanied by a chain extension.

FIG. 2 represents the infrared spectrum of the composition according to the invention comprising, in mixture, the copolymer and the starch, which reveals the presence of starch, of ester groups and of double bonds, all the corresponding numerical data being combined in Tables 3 to 9 below, each table being specific to a particular peak. Table 3 Pic No. 1

MN = 1447462 MW = 1837085

Table 4 Pic No. 2

MN = 127,869 MW = 191,696

Table 5 Pic No. 3

MN = 19989 MW = 26050

Table 6 Pic No. 4

MN = 2304 MW = 3442

Table 7 Pic No. 5

MN = 846 MW = 848 Table 8 Pic No. 6

MN = 662 MW = 666

Table 9 Pic No. 7

MN = 467 MW = 472

Claims

Linear biodegradable thermoplastic copolymers of the polyester type, obtained by polycondensation of saturated monomers of general formulas:

(a) of the diacid type HO-CO-D-CO-OH,

(b) of HO-E-OH diol type,

(c) and / or of the acid-alcohol type HO-F-COOH,

in which D, E, F are saturated hydrocarbon chains characterized in that, to these monomers of type (a), (b) and / or (c) are associated with at least two other coupled monomers having functional groups -COOH and -OH capable of reacting with the functional groups of said monomers of type (a), (b) and / or (c), and / or between them,

(d) the first coupled monomer provided with a tertiary carbon corresponding to the general formula:

in which :

- m> 1

- the couple Y ^ Y ₂ of the tertiary carbon is of the type (-COOH, -OH) (-COOH, R, (-OH-Ri) where Ri is H or a hydrocarbon chain

- X-ι and X ₂ , placed at the ends of said monomer, are chosen from the group consisting of two by two combinations of the acid and alcohol reactive functions, giving Xι = X ₂ = -COOH or χ _{1 =} χ ₂ = _OH or Xi≈-COOH and X ₂ = -OH

where n> 0, p> 0, q> 0, and where R ₂ , R ₃ and R are chosen from the group consisting of reactive functions, -COOH, -OH or aliphatic hydrocarbon chains of type - (CH ₂ ) _r CH ₃ with r> 0.

(e) the second coupled monomer being an acid anhydride with double bond = C corresponding to the general formula:

in which R ₅ and Rβ are chosen from the group consisting of hydrogen -H, aliphatic hydrocarbon chains, branched or not, of the type - (CH ₂ ) _r -CH ₃ with r> 0.

Linear biodegradable thermoplastic copolymers according to claim 1, characterized in that, in the monomer of type d) corresponding to the general formula:

m can be between 1 and 4 but is preferably equal to 1.

When the couple Yi, Y ₂ of the tertiary carbon is of the -COOH, Ri or -OH, Ri type, the hydrocarbon chain Ri is a Ci to Cι ₈ chain and preferably a Ci to C ₈ chain. , f ^•

in groups A and B, which are each linear aliphatic hydrocarbon chains, optionally branched, comprising at least one of the hydrocarbon groups chosen from the group consisting of:

- n takes a value between 1 and 5, preferably equal to 1;

- p takes a value between 1 and 5;

- q takes a value between 1 and 5;

* in R ₂ , R ₃ and R ₄ , which are chosen from the group constituted by the reactive functions, -COOH, -OH, and the aliphatic hydrocarbon chains of the type - (CH ₂ ) _r CH ₃ , r takes a value included between 1 and 5.

3. Linear biodegradable thermoplastic copolymers according to either of Claims 1 and 2, characterized in that the monomer of type d) is preferably citric acid.

4. Linear biodegradable thermoplastic copolymers according to at least one of claims 1 to 3, characterized in that, in the monomer of type e), corresponding to the general formula:

R ₅ and Rβ are aliphatic hydrocarbon chains, branched or not, of the type - (CH ₂ ) r-CH ₃ where r is chosen between 1 and 5.

5. Linear biodegradable thermoplastic copolymers according to at least one of claims 1 to 4, characterized in that the monomer of type e) is preferentially chosen from the group consisting of maleic anhydride, itaconic anhydride, ji hydride citraconic, tetrahydro-phthalic anhydride 3, 4, 5, 6.

6. Linear biodegradable thermoplastic copolymers according to at least one of claims 1 to 5, characterized in that, in the other monomers which correspond to the general formulas:

HO-CO-D-CO-OH of the diacid type, for type a),

HO-E-OH of the diol type, for type b), and / or HO-F-COOH of the acid-alcohol type, for type c), in which D, E and F are linear, optionally branched, aliphatic hydrocarbon chains comprising at least one of the groups:

- S is preferably between 1 and 8, - T takes a value between 1 and 5,

- U takes a value between 1 and 5,

- In R2, R3, 4, which are chosen from aliphatic hydrocarbon chains of the (-CH ₂ ) rCH _{3 type} , r takes a value between 1 and 5.

7. Linear biodegradable thermoplastic copolymers according to at least one of claims 1 to 6, characterized in that the monomer of type a) is a diacid preferably chosen from the group consisting of succinic acid, sebacic acid, phthalic acid, isophthalic, terephthalic, malonic acid, adipic acid, diglycolic acid, glutaric acid.

8. Linear biodegradable thermoplastic copolymers according to at least one of claims 1 to 7, characterized in that the monomer of type b) is a dialcohol preferably chosen from the group consisting of ethylene glycol, diethylene glycol, propylene glycol and the dipropylene glycol, propane diol, butane diols 1-2, 1-3, 1-4, 2-3, pentane diols 1-5 and 1-6, hexanediol. é 9. Linear biodegradable thermoplastic copolymers according to at least one of claims 1 to 8, characterized in that the monomer of type (c) is an acid-alcohol preferably chosen from the group consisting of lactic acid, the acid glycolic, hydroxypropanoic acid, hydroxybutanoic acid, hydroxy pentanoic acid.

10. Linear biodegradable thermoplastic copolymers according to at least one of claims 1 to 9, characterized in that the relative amounts of the monomer of type (d) provided with a tertiary carbon vary in industrial use between 1% by mole and 30% by mole and, preferably, between 1% by mole and 20% by mole of the total of all the monomers present in the composition carrying the same type of reactive functions.

11. Linear biodegradable thermoplastic copolymers according to at least one of claims 1 to 10, characterized in that the relative amounts of the monomer of type (e) are chosen in industrial use between 1% by mole and 30% by mole and, preferably , between 1% by mole and 20% by mole of the total of all the monomers present in the composition carrying the same type of reactive functions.

12. Linear biodegradable thermoplastic copolymers according to at least one of claims 1 to 11, characterized in that the relative amounts of the monomer of type (d) having a tertiary carbon which is a diacid, a diol or an acid-alcohol and monomer of type (e) which is the unsaturated organic acid anhydride which intervenes in a coupled mixture in the polycondensation reaction by esterification, vary with respect to one another from 1% to 99% by moles and, preferably , from 1% to 60% in moles of equivalent of acid functions for organic anhydride of type (e) and from 99% to 1% in moles of equivalent of acid functions, and preferably from 99% to 40% for acid monomers of type (d).

13. Linear biodegradable thermoplastic copolymers according to at least one of claims 1 to 12, characterized in that the ratio of the reactive functional groups -OH and -COOH to the exclusion of the reactive reactive groups bound to tertiary carbons and to acid-alcohols present, varies between limits:

[-OH] p, 0, 95 <<1, 05

[-COOH] ι

14. Linear biodegradable thermoplastic copolymers according to at least one of claims 1 to 13, characterized in that their molecular mass is between 500 and 100,000 and, preferably, between 2,000 and 30,000.

15. Compositions comprising at least one copolymer defined according to at least one of claims 1 to 14, and at least one ion chosen from the group preferably made up of Ca ²⁺ , Mg ²⁺ , Zn ²⁺ , Al ³⁺ , Si ⁴⁺ , Ti ⁴⁺ and / or at least one oxide chosen from the group consisting of a calcium oxide, a magnesium oxide, a zinc oxide, an aluminum oxide, a silicon oxide, a titanium oxide.

16. Compositions according to claim 15, characterized in that they also comprise at least one biodegradable natural polymer.

17. Compositions comprising at least one copolymer defined according to at least one of claims 1 to 14 and at least one biodegradable natural polymer.

"

18. Compositions according to at least one of claims 15, 16 or 17, characterized in that:

- The at least one copolymer is present in an amount of 30% to 100% by weight and, preferably, from 50% to 90% by weight relative to the total weight of the composition;

- The biodegradable natural polymer is present in an amount of 70% to 0% by weight and, preferably, from 50% to 10% by weight relative to the total weight of the composition.

19. Compositions according to at least one of claims 16 to 17, characterized in that the at least one biodegradable natural polymer is chosen from the group consisting of carbohydrates which are polysaccharides, proteins, nucleic acids, amino acids and lipids.

20. Compositions according to claim 19, characterized in that the at least one natural polymer chosen is preferably a polysaccharide and, more particularly, starch and / or gluten and / or cellulose.

21. Compositions according to claim 19, characterized in that the at least one natural polymer is a protein chosen from those originating from eggs and / or milk and / or cereals.

22. Compositions according to claim 19, characterized in that the at least one natural polymer is a lipid chosen from those originating from vegetable oils.

23. Compositions according to at least one of claims 15 to 22, characterized in that they contain agents usually used in polymer compositions, in particular, dyes, pigments, mineral fillers, antioxidants, UV inhibitors, plasticizers, flame retardants.

24. Compositions according to at least one of claims 15 to 23, characterized in that they contain other polymeric materials such as polyvinyl alcohols, copolymers of ethylene and vinyl alcohol, polyamides, polyurethanes, polyacrylics, polycarbonates, alone or as a mixture.

25. Compositions according to claim 24, characterized in that the other polymeric materials are present in an amount of 1 to 25 parts by weight per 100 parts by weight of copolymers defined according to at least one of claims 1 to 14 or of defined compositions according to at least one of claims 15 to 24.

26. Compositions according to at least one of claims 15 to 25, characterized in that the at least one copolymer defined according to at least one of claims 1 to 14 is crosslinked by opening the double bonds of the unsaturated anhydride.

27. Process for the preparation of copolymers as defined in at least one of claims 1 to 14, characterized in that the polycondensation of the monomers of types (a), (b), (c), (d) and (e )

- takes place in a thin-film reactor,

- in the absence of catalyst,

- at a temperature between 110 ° C and 170 ° C, - with "in situ" elimination of the gaseous phases formed,

- possibly with the addition of various agents of known types,

- then extrusion and cutting of the extruded material.

28. Process for preparing the compositions as defined in at least one of claims 15 to 26, characterized in that:

- In a first step, polycondensation of the monomers of types (a), (b), (c), (d) and (e) is carried out, in the absence of a catalyst, in a thin-film reactor, reaction medium being placed at a temperature comprised, and being able to evolve, between 110 ° C. and 170 ° C., with elimination of the aqueous phases formed;

- In a second step, at least one natural biodegradable polymer and / or at least one is introduced into the thin-film reactor, within the copolymer formed. ion chosen from the group consisting of Ca ²⁺ , Mg ²⁺ , Zn ²⁺ , Al ³⁺ , Si ⁴⁺ , ti ⁴⁺ and / or at least one oxide chosen from the group consisting of CaO, MgO, ZnO, AI ₂ O ₃ , SiO ₂ , TiO ₂ , optionally with the addition of various agents of known types, the reaction medium being maintained at a temperature not exceeding 170 ° C;

- Then the extrusion and the granulation of the extruded material are carried out.

29. Preparation process according to either of claims 27 or 28, characterized in that the at least one copolymer defined according to at least one of claims 1 to 14 is crosslinked, chemically, in the presence of '' a suitable catalyst chosen from the group consisting of methyl ethyl ketone peroxide associated with a cobalt salt, benzoyl peroxide alone or associated with a tertiary amine, cumene hydroperoxide, methyl isobutyl hydroperoxide ketone, lauryl peroxide, cyclohexanone peroxide, dicumyl peroxide.

30. Preparation process according to one or the other; claims 27 or 28, characterized in that the at least one copolymer defined according to at least one of claims 1 to 14 is, crosslinked by ultraviolet, infrared or electronic irradiation.

31. Use of the copolymers defined according to at least one of claims 1 to 14, and of the compositions defined according to at least one of claims 15 to 26, according to their molecular weights, by adjusting their formulation, in the production of articles, in particular contact or contactless smart cards, electronic labels, waterproof films, toys, or used as adhesives, printing inks.