COMPOSITION COMPRISING A RIGID (CO)POLYESTER AND A FLEXIBLE (CO)POLYESTER, METHOD FOR PREPARING SAME AND USE THEREOF IN GEOTEXTILE AND FOR FISHING MACHINERY The present invention relates to the field of compositions comprising biodegradable (co)polyesters, as well as to articles manufactured from these compositions, preferably obtained by spinning extrusion.
Prior art Globalisation, the consumer society and the increase in population density are all factors that lead companies to a high production of plastic materials obtained from petroleum- derived compounds, also referred to as oil-based materials.
These are, for example, polyolefins such as polyethylene (PE) and polypropylenes (PP), polyamides such as polyamide 6 (Nylon), polyesters such as polybutylene terephthalate (PBT), to which are added additives that modify their properties.
These articles generally have good physical properties, have a long service life and are particularly suitable for use in marine environments.
In 2014, global production of these oil-based materials amounted to approximately 311 million tonnes, of which only a tiny fraction is recycled.
Pollution of the oceans by these oil-based materials is particularly worrying.
The amount of oil-based plastic in the oceans is estimated at 270,000 tonnes.
These oil-based plastics will impact and weaken biota directly and for a long time (sometimes for hundreds of years), for example by participating in the migration of species clinging to their structures as they drift in the oceans, by becoming part of the food cycle of aquatic fauna, by releasing their additives or polluting compounds following their fragmentation or decomposition into particles, by contributing to the disruption of the carbon cycle and the acidification of the oceans.
In order to limit pollution, recycling channels have been set up to collect, process and potentially reuse items made from used oil-based materials.
Such channels are generally expensive to implement and only allow the partial recycling of used items.
In fact, only two types of plastics are recycled, namely PET (used in particular for the manufacture of transparent or coloured bottles) and HDPE (used in particular for the manufacture of opaque bottles). Other plastics such as PVC, polyamides that are mainly used in monofilaments, or those of supermarket bags and films are not recycled due to the prohibitive cost of recycling.
Similarly, it is very difficult to recycle articles incorporating nanoparticles as fillers.
These items are burned in incinerators to produce energy: this is referred to as “energy recovery”. However, plastic is not infinitely recyclable: recycling it only delays the moment when it will be burned.
In this context, it seems essential to offer alternative materials such as biodegradable and/or biobased plastics, making it possible to limit human dependence on fossil fuels, minimise the amount of polluting chemical compounds, reduce the carbon impact of manufactured products, solve many problems of congestion in landfills, emission of harmful gases during incineration - due to their compostability - and finally to overcome the negative impacts of oil-based plastics on the fauna and flora and, more generally, the ecosystem, in particular marine ecosystems.
For several decades now, significant university and industrial research has focused on the development of biobased and/or biodegradable materials, such as, for example, the family of biodegradable polyesters, the family of polyhydroxyalkanoates, the family of agro-polymers.
However, the materials available on the market are not always suitable for producing articles for technical applications or for use over a reasonable lifetime in “aggressive” environments.
Among these so-called "technical" articles, mention will be made more particularly of fishing gear (lines) intended for use in sea water (which is a bacterial environment, under a maximum humidity rate, and with high salt content) or even geotextiles used on beaches in areas with high exposure to UV rays.
In addition, these materials are often difficult to implement, in particular in extrusion processes - spinning, calendering, foaming, blowing - often because they have been weakened by thermal degradation or because of the poor performance of the mixtures they are made of.
To limit the environmental impact of plastic materials and increase their field of application, it is therefore necessary to provide compositions of biodegradable materials that also have physical properties, and in particular strength properties, that are acceptable in particular for technical applications under “aggressive” environmental conditions.
The present invention aims to meet this need.
Aliphatic and aromatic biodegradable (co)polyesters and, in particular, mixtures thereof, are considered promising routes.
However, the compatibility of aliphatic and aromatic biodegradable (co)polyesters is naturally weak and this weakness is further accentuated at high molar masses.
The mixtures obtained generally have unsatisfactory results in terms of microstructural morphology, homogeneity, distribution, dispersion, miscibility and/or interface as well as a poor capacity to be extruded, which leads to articles that do not have not have the desired characteristics and physical properties.
Mixtures of biodegradable (co)polyesters are already known in particular in applications WO 99/23163 or even JP 2011-234718. However, these applications do not mention the composition according to the invention that combines particular biodegradable (co)polyesters with a vinyl polymer and has improved properties, particularly in terms of mechanical properties and suitability for industrial implementation.
In particular, JP 2011-234718 does not disclose a composition comprising from 0.5 to 10% by weight of a vinyl polymer.
Patent application FR 3 040 389 A1 discloses compositions comprising rigid copolyesters and polyvinyl acetate.
This patent application does not disclose compositions comprising at least one rigid biodegradable (co)polyester, at least one flexible biodegradable (co)polyester and a vinyl polymer in the proportions according to the present invention.
Thus, the authors of the present invention have demonstrated a composition based on biodegradable (co)polyesters having both a good capacity for implementation on an industrial scale, while retaining satisfactory physical and mechanical properties, in particular, in terms of strength, said composition allowing prolonged use under particularly aggressive conditions.
The composition according to the invention can advantageously be used in technical and specific applications.
Summary of the invention The subject of the present invention is therefore a composition, preferably biodegradable, comprising: - from 40% to 90%, preferably from 50% to 90%, by weight of at least one rigid biodegradable (co)polyester, relative to the total weight of the composition, - from 10% to 49% by weight of at least one flexible biodegradable (co)polyester, relative to the total weight of the composition, - from 0.5% to 10% by weight of a vinyl polymer relative to the total weight of the composition, said composition being such that - the difference in melting temperatures between the two biodegradable (co)polyesters having the furthest melting temperatures is less than 25 °C, preferably less than 15°C, preferably less than 10°C, the melting temperatures being determined according to standard ISO 3146, - the difference in the melt flow indices between the two biodegradable
(co)polyesters having the furthest melt flow indices is less than 5 g/10 min, preferably less than 3 g/10 min, the melt flow indices being determined according to standard ISO 1133, a rigid (co)polyester being a polymer having a rigidity modulus greater than 500 MPa, preferably greater than 600 MPa and an elongation at break of less than 300%, preferably less than 250%, a flexible (co)polyester being a polymer having a rigidity modulus of less than 850 MPa, preferably less than 700 MPa and an elongation at break greater than 100%, preferably greater than 200%, the rigidity modulus and the elongation at break being determined according to standard NF EN ISO 527-1, when the composition comprises a biodegradable (co)polyester having a rigidity modulus between 500 and 850 MPa and an elongation at break between 100 and 300%, then it also contains either at least one (co)polyester having a rigidity modulus greater than 850 MPa and an elongation at break of less than 100% or at least one (co)polyester having a rigidity modulus of less than 500 MPa and an elongation at break greater than 300%. The inventors have shown that, surprisingly, the combination of at least two particular biodegradable (co)polyesters and a vinyl polymer makes it possible to obtain compositions with particularly advantageous properties.
The composition according to the invention is obtained from biodegradable polymers, and as a result a first advantage is that it can itself be biodegradable and/or recyclable.
The composition according to the invention allows producing environmentally friendly articles having a significantly lower impact on the environment compared to articles made from non-biodegradable petrochemical plastics.
Another advantage of the composition according to the invention is that it has good processability properties, in particular by melt spinning extrusion, both on a laboratory scale and on an industrial scale, while retaining physical and mechanical properties that are satisfactory or even very good for the applications envisaged.
This composition is also distinguished by its homogeneity, advantageously allowing the preparation of articles such as yarns, monofilaments, multifilaments, fibres, horsehair, cosmetic hair, nets, braids, ropes, woven fabrics, nonwoven fabrics, films, blown structures, tube profiles.
Another advantage of this composition lies in its physical and mechanical properties, in particular its thermal resistance and its resistance to abrasion.
According to a second object, the invention relates to a method for preparing the composition according to the invention comprising an extrusion step, preferably a melt spinning extrusion step, advantageously by means of a single-screw extruder.
The composition according to the invention has good spinnability, and enables obtaining articles with good strength.
The present invention also relates to the use of the composition according to the invention for preparing articles selected from the group formed by yarns, monofilaments, multifilaments, fibres, horsehair, cosmetic hair, nets in particular for gear fishing and/or for the food sector, braids, ropes, woven fabrics, nonwoven fabrics, films, blown structures, tube profiles.
Therefore, another object of the invention is an article obtained by spinning extrusion of a composition according to the invention or obtained according to the method according to the invention, said article being selected from the group formed by yarns, monofilaments, multifilaments, fibres, horsehair, cosmetic hair, nets in particular for fishing and/or food gear, braids, ropes, woven fabrics, nonwoven fabrics, films, blown structures, tube profiles, preferably monofilaments.
These articles are distinguished by their remarkable physical properties in terms of toughness, breaking strength, tensile strength, rigidity, thermal resistance, abrasion resistance.
In particular, the composition according to the invention is advantageously used for the production of monofilaments, advantageously the composition according to the present invention is used in or for the manufacture of articles selected from fishing gear or geotextiles, in particular usable in marine or seaside environments, these items being environmentally friendly.
The invention thus aims at an environmentally friendly article selected from fishing gear or geotextiles.
By "environmentally friendly" we mean the property of respecting nature and the environment as much as possible.
Other objects, aspects, advantages and properties of the present invention are presented in the description and the examples below.
Definitions The following definitions are used throughout this text. “Monofilament” means a single thread obtained by coagulation of a continuous flow of liquid, as in the manufacture of artificial textiles or by spinning with cold drawing, as in the manufacture of polyamide threads, or by extrusion with drawing.
The term "biodegradable" or "biodegradability" means the property of a material to degrade by biological activity, for example by the action of enzymes and/or micro- organisms, by a reduction in its molar mass, in particular the decomposition of an organic chemical compound into carbon dioxide, water and mineral salts, any other elements present (mineralisation) and the appearance of a new biomass, by the action of micro- organisms in the presence of oxygen; or the decomposition into carbon dioxide, methane, mineral salts and the creation of a new biomass, in the absence of oxygen (it is defined by European Standard EN 13432:2000 and its extension in France: NF 14995). “Recyclable” means the recovery of some or all of the constituents of a material that has reached the end of its useful life or of a material made of manufacturing residues in order to reintroduce them into the production cycle of the same material or another material. “Compostable” or “compostability” means a process that consists in placing fermentable products under conditions (of temperature, humidity, oxygenation, presence of soil micro- organisms, etc.) that enable their biodegradation.
To be considered compostable within the meaning of standard EN 13432, the material must be degraded to 90% of its mass after 6 months in an industrial compost environment; the size of the residues must be less than 2 mm after 3 months of composting; and the absence of ecotoxic effects must be demonstrated as well as the agricultural quality of the compost obtained. “Biobased” means plastics made from resources of plant origin such as corn, cassava, potato, wood, cotton, algae, sugar cane, beet... the nature of biobased products is defined by standard ASTM D6866. Detailed description Composition The composition according to the present invention comprises a mixture of at least two biodegradable (co)polyesters.
According to a first advantageous variant, in order to increase the environmental contribution of the composition according to the invention, at least one of the biodegradable (co)polyesters used is biobased, more preferably all the biodegradable (co)polyesters used are biobased.
Advantageously, the composition according to the present invention is biodegradable, preferably it is also compostable.
The inventors estimate the biodegradation of the articles obtained from said composition to be obtained within a period ranging from 5 to 30 years depending on the degradation medium and climatic variability.
Biodegradation mechanisms can be biotic under the action of micro-organisms (enzymatic hydrolysis, enzymatic oxidation, degradation by organic acids, etc.) or abiotic, depending on the medium (acid-base hydrolysis, oxidation, photo-degradation, thermo-degradation, acid-basic reaction of substrates, etc.); mention is made more particularly of hydrolytic degradation, enzymatic degradation by lipases, degradation by oxidation, microbial degradation, thermal degradation.
Furthermore, the articles obtained from the composition according to the invention can, under very specific conditions such as the hot and humid environments of industrial composts defined according to standards EN 13432, EN 14995, for example, degrade much more quickly, around 90% biodegraded in 6 months, and thus have the advantage of reducing landfill congestion issues.
Advantageously, the articles obtained from the composition according to the present invention are recyclable.
The composition according to the present invention comprises a mixture of at least two biodegradable (co)polyesters, that is to say at least one rigid biodegradable (co)polyester and at least one flexible biodegradable (co)polyester, and a vinyl polymer. “Rigid (co)polyester”, within the meaning of the present invention, means a polymer having the following characteristics: a rigidity modulus greater than 500 MPa, preferably greater than 600 MPa and an elongation at break of less than 300%, preferably less than 250%. Advantageously, the “rigid (co)polyester” used according to the present invention has: - arelative degree of crystallinity ranging from 15% to 80%, preferably ranging from 15% to 60%, by weight relative to the total weight of said (co)polyester, that is to say a semi- crystalline polymer or - a glass transition temperature (Tg) greater than or equal to room temperature. “Flexible (co)polyester”, within the meaning of the present invention, means a polymer having the following characteristics: a rigidity modulus of less than 850 MPa, preferably less than 700 MPa and an elongation at break greater than 100%, preferably greater than 200%. Advantageously, the “flexible (co)polyester” used according to the present invention has: - arelative degree of crystallinity ranging from 0% to 30%, preferably ranging from 0% to 15%, by weight relative to the total weight of said (co)polyester, that is to say an amorphous or weakly crystalline polymer and - a glass transition temperature (Tg) below room temperature.
Room temperature is equal to 20 °C.
In addition, when the composition according to the invention comprises a biodegradable
(co)polyester having a rigidity modulus between 500 and 850 MPa and an elongation at break between 100 and 300%, then it also contains either at least one (co)polyester having a rigidity modulus greater than 850 MPa and an elongation at break of less than 100% or at least one (co)polyester having a rigidity modulus less than 500 MPa and an elongation at break greater than 300%. The rigidity modulus, also referred to as elasticity modulus or Young's modulus, is calculated from a tensile test performed on a specimen between two jaws and a movement produced at a controlled speed on a mechanical testing machine.
It is determined from the linear elastic deformation curve according to standard NF EN ISO 527-1 (2012-04-01), such that: Rigidity modulus (MPa)= of2 = oft ef2 — eft Where: ofl is the stress, expressed in MPa, measured at the strain value of ef1= 0.0005. of2 is the stress, expressed in MPa, measured at the strain value of ef2= 0.0025. The elongation at break is calculated from a tensile test performed on a specimen between two jaws and a movement produced at a controlled speed on a mechanical testing machine.
It is determined by the variation in sample length over the initial length of the sample according to standard NF EN ISO 527-1 (2012-04-01), such that: Elongation at break (%) = Sample length before break — Initial sample length Initial sample length Thus, the composition according to the present invention comprises at least one rigid biodegradable (co)polyester and at least one flexible biodegradable (co)polyester such that: the rigidity modulus of the rigid biodegradable (co)polyester is greater than the rigidity modulus of the flexible biodegradable (co)polyester, preferably by a ratio rigidity modulus of the rigid biodegradable (co)polyester/rigidity modulus of the flexible biodegradable (co)polyester greater than or equal to 2, and the elongation at break of the flexible biodegradable (co)polyester is greater than the elongation at break of the rigid biodegradable (co)polyester, preferably by a ratio elongation at break of flexible biodegradable (co)polyester/elongation at break of rigid biodegradable (co)polyester greater than or equal to 1.5. The concept of relative degree of crystallinity, Xc, measures the proportion of matter that is in the crystalline state.
X-ray diffraction and calorimetric analysis (“Differential Scanning Calorimetry”) are the main physical techniques for measuring the relative degree of crystallinity.
The relative degree of crystallinity is calculated by scanning calorimetry (DSC). It is determined by the integration of the enthalpy of fusion and crystallisation during the heating of the material, according to standard ISO 11357-3, and the normalisation with respect to the 100% crystalline material, such that: x AH melting - AH crystallisation € AH melting material 100% The degree of crystallinity can also be calculated by wide angle X-ray diffraction (WAXD, WAXS). The diffraction of the material is then the contribution of its crystalline phase (crystalline lines) and of the amorphous phase (amorphous halo). The degree of crystallinity is measured by evaluating the relative area of these two parts: Xc= Crystalline phase area Crystalline phase area + Amorphous phase area For the purposes of this text, scanning calorimetry (DSC) is the preferred method for measuring crystallinity.
The glass transition temperature is measured by differential scanning calorimetry (DSC). Thus, the composition according to the present invention comprises at least one rigid biodegradable (co)polyester and at least one flexible biodegradable (co)polyester.
Advantageously, the difference between the degree of crystallinity of the rigid (co)polyester with the lowest degree of crystallinity and the degree of crystallinity of the flexible (co)polyester with the highest degree of crystallinity is greater than or egual to 5%, preferably greater than or egual to 10%. Preferably, when the composition according to the invention comprises a rigid biodegradable (co)polyester and a flexible biodegradable (co)polyester, then the difference between the degree of crystallinity of the rigid (co)polyester and the degree of crystallinity of the flexible (co)polyester is greater than or equal to 5%, preferably greater than or equal to 10%. Said at least one rigid biodegradable (co)polyester accounts for most of the weight relative to the weight of all the biodegradable (co)polyesters.
Without wishing to be bound by any theory, it appears that in order to present the properties described above, namely good properties for processability, in particular on an industrial scale, while retaining satisfactory physical and mechanical properties, the composition according to the invention must have a so-called "sea-island" biphasic morphology in which the flexible biodegradable (co)polyester(s) form(s) the minority phase that is dispersed within the phase of the rigid biodegradable (co)polyester(s) that constitute(s) the matrix.
The “suitability for processing” is also referred to as “suitability for implementation” or even “processability”. The composition according to the invention is thermally stable under recommended conditions of use or implementation: it does not significantly degrade under thermal effect when it is subjected to temperature variations in particular during its preparation, or when preparing articles from this composition.
In addition, articles obtained from this composition do not degrade when they are subjected to temperature variations, in particular between -10 °C and 80 °C.
The inventors have also observed that the composition according to the invention has satisfactory physical and mechanical properties, in particular in terms of resistance to abrasion, tensile strength.
The composition according to the invention is also satisfactory in terms of rheological properties and, more particularly, in terms of microstructural morphology, homogeneity, distribution, dispersion, miscibility and interface of the various constituents, i.e. the (co)polyesters.
The lifespan of an article according to the invention (application) ranges from 1 to 10 years, preferably from 1 to 5 years depending on the application, the stress and the application environment, which can be terrestrial, mountainous, marine, lacustrine, tropical, Mediterranean, temperate.
Advantageously, the articles according to the present invention are used in a marine environment: immersed in and/or next to the sea.
The present invention also makes it possible to obtain a composition suitable for contact with food.
Biodegradable (co)polyesters The biodegradable (co)polyesters used in the composition according to the invention are advantageously selected from the group formed by polylactic acid, polyglycolic acid, polyhydroxyalkanoates and copolymers thereof; aliphatic polyesters, in particular, polybutylene succinate, aromatic and semi-aromatic polyesters as well as poly(e- caprolactone) and copolymers thereof, in particular, polybutyrate or polybutylene adipate terephthalate and copolymers thereof.
Biodegradable (co)polyesters can be obtained from biobased monomers or from synthetic monomers, preferably from biobased monomers.
As already mentioned, biodegradable (co)polyesters have a high average molar mass,
advantageously their average molar mass ranges from 104 to 105 g/mol.
Poly(lactic acid), poly(glycolic acid) and (co)polymers thereof Several steps are necessary to obtain poly(lactic acid): (1) fermentation of dextrose to form lactic acid, (2) polymerisation of lactic acid into an oligomer, (3) depolymerisation of said oligomer into lactide, and (4) polymerisation of lactide into poly(lactic acid). First of all, lactic acid {cyclic monomer) is produced from renewable resources (corn, starch) by fermentation of glucose, more specifically D-glucose, also referred to as dextrose, extracted by hydrolysis from the starch contained in the biomass.
After having isolated the dextrose from the starch, the latter is subjected to fermentation generally by means of a bacterium of the genus Lactobacillus.
The lactic acid obtained at the end of the fermentation is then used in two subsequent reactions: polycondensation, which leads to the production of an oligomer and a ring- opening polymerisation.
These two reactions are necessary to produce poly(lactic acid) of high molar mass.
In order to obtain a high molar mass polymer, the oligomer is depolymerised to obtain lactide.
The lactide (intermediate substance) is polymerised again in the presence of catalysts, but this time by ring opening in order to produce the poly(lactic acid) also referred to as polylactide.
The polymer thus formed by this type of reaction has a high molar mass.
Poly(lactic acid) is advantageously used in the compositions according to the invention.
In addition, as polylactide is made from the two main variants of the monomer: L-lactic acid (usually produced in large quantities during the fermentation process) and D-lactic acid, three forms of polylactide exist: poly(D-lactide) (PDLA), poly(L-lactide) (PLLA), as well as poly(DL-lactide) (PDLLA), a copolymer resulting from the two variants of the monomer.
In order to obtain the desired properties, most industrially produced polylactide consists of a mixture of PLLA and PDLLA.
However, the proportion of PLLA is higher since this polymer is obtained in greater quantity.
Poly(glycolic acid) PGA, also referred to as polyglycolide, is obtained in the same way by polycondensation of glycolic acid or by opening of the glycolide ring.
Poly(glycolic acid) is advantageously used in the compositions according to the invention.
It is also possible to copolymerise L-lactide and DL-lactide with glycolic acid to synthesise poly(lactic-co-glycolic acid) (PLGA). This copolymerisation makes it possible in particular to improve the biodegradation properties of PLA.
Polylactides, polyglycolides and copolymers thereof can be softened by the use of a plasticiser, which will notably reduce their glass transition temperatures, their rigidity.
These are then called "plasticised polylactide", "plasticised polyglycolide" and "plasticised poly(lactic-co-glycolic acid)". Polylactide, polyglycolide and poly(lactic-co-glycolic acid) are advantageously used as biodegradable (co)polyesters in the compositions according to the invention.
Polyhydroxyalkanoates (PHA) and their co(PHA) copolymers PHAs are biopolymers synthesised by bacterial fermentation, in particular bacteria of the genus Halobacteriaceae.
It is according to the synthesis parameters (micro-organism, hydrocarbon substrates) that the different types of macromolecular architectures of the PHAs and the different (co)polymers of this family will be formed.
These macromolecular architectures will lead to PHAs with different properties.
Several steps are necessary for the production of PHA by bacterial fermentation.
The first step is the conversion of the carbon source to acetate.
Then an enzyme, referred to as coenzyme A (CoA), attaches to it via a chemical bond.
A molecule is then formed by a process of condensation to create acetoacetyl-CoA, which will be reduced to a monomer, hydroxybutyryl-CoA.
PHA is finally formed by polymerisation of the monomer, which occurs spontaneously.
This entire process takes place inside the bacteria themselves.
The first, industrial, method for obtaining PHAs involves 3 steps: bacterial fermentation, extraction by solvent (solubility of PHAs in chloroform and not in methanol) or by enzyme cocktails or mechanically, and finally purification.
It seems important to indicate that the solvent extraction method consumes a large quantity of non-ecological solvents.
Consequently, PHAs obtained by methods implementing an extraction by enzyme cocktails or mechanically will preferably be used in the compositions according to the present invention.
The PHAs thus obtained are usually classified according to the number of carbon atoms on their pendant group: in short chain (between 4 and 5 atoms), medium chain (6 to 14 atoms) and long chain (more than 14 atoms). The second method consists of biosynthesis using genetically modified organisms.
This method aims to increase the yields or to diversify the species of bacteria capable of producing PHAs.
It also makes it possible to obtain polymers of greater molar mass.
The third method, classical chemical synthesis, consists of synthesising the PHA by ring opening.
This method does not use bacteria, but rather lactones used as monomers.
Catalysts based on zinc, aluminium or enzymes are used.
Although the PHAs synthesised by this method are almost identical to those produced by bacterial synthesis, the production costs are higher.
The PHA copolymers contain other B-hydroxy acids and in differing proportions, depending on the conditioning, the food of the bacteria, for example PHB homopolymer: PHB-co-PHV copolymer.
The rigid or flexible nature of these copolymers can be controlled according to the B-hydroxy acid types used and their proportions.
PHA (co)polymers are referred to as (co)PHA.
Preferably, the (co)PHAs used in the compositions according to the present invention are selected from the group formed by poly(3-hydroxypropionate), poly(3-hydroxybutyrate), poly(3-hydroxyvalerate), poly(3-hydroxyhexanoate), poly(3-hydroxyoctanoate), poly(3- hydroxynonanoate), poly(3-hydroxydecanoate), poly(3-hydroxyundecanoate), poly(3- hydroxydodecanoate), poly(3- hydroxyoctadecanoate), poly(4-hydroxybutyrate), poly(5- hydroxybutyrate), poly(5-hydroxyvalerate), and copolymers thereof such as poly(hydroxybutyrate-co-hydroxyvalerate) P(3HB-co-3HV) also referred to as PHBV, poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) P (3HB-co-3HHx)) also referred to as PHBH, poly (3-hydroxybutyrate-co-3-hydroxyoctanoate) P (3HB-co-3HO), poly(3- hydroxybutyrate-co-4 hydroxybutyrate) P(3HB-co-4HB). Advantageously, the PHA (co)polymers used in the compositions according to the invention are selected from poly(3-hydroxybutyrate) or PHB, Poly(3-hydroxyvalerate) or PHV, Poly(3-hydroxyoctanoate), poly (hydroxybutyrate-co-hydroxyvalerate) or PHBV, poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) or P(3HB-co-3HHx)) also referred to as PHBH, poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) or P(3HB-co-3HO), poly(3- hydroxybutyrate-co-4hydroxybutyrate) or P(3HB-co-4HB). Aliphatic polyesters and copolymers thereof, in particular polybutylene succinate, and copolymers thereof.
The biodegradable aliphatic (co)polyesters used in the composition according to the invention are advantageously selected from the group formed by polyethylene adipate, polybutylene succinate (PBS) and copolymers thereof such as polybutylene succinate- co-adipate (PBSA), polybutylene succinate-co-lactate (PBSL). A first method, the most widespread and the simplest, for obtaining PBS is direct polymerisation by melt polycondensation transesterification.
High molar mass PBS is obtained from succinic acid and 1,4-butanediol, in the presence of a catalyst based for example on antimony, tin and titanium, such as tetrabutyl titanate and isopropyl.
A second method is direct polycondensation by solvent transesterification polycondensation, the distillation of water under azeotropic conditions allowing the preservation of a high concentration of reagents and the formation of polymers of relatively high molar mass.
A third method is solid-state transesterification polycondensation polymerisation, PBS being synthesised in bulk from dimethyl succinate and 1,4-butanediol, and having a low molar mass.
A fourth method is the synthesis of PBS by polycondensation, which can be followed by chain extension, making it possible to obtain PBS of high molar mass.
A fifth method is the synthesis of biobased PBS from biobased succinic acid.
This synthesis of biobased succinic acid is different from the synthesis of oil-based succinic acid from naphtha because succinic acid is produced from the bacterial fermentation of glucose, sucrose or cellulose from 100% renewable sugar resources from cane, tapioca, wheat, corn and non-food biomass.
The reaction does not use a metal catalyst or chemical solvent.
The second molecule used in the synthesis of biobased PBS is butanediol.
In this fifth method, it is possible to obtain biobased butanediol either from glucose by direct fermentation of glucose into biobased butanediol or by fermentation of glucose into biobased succinic acid then by hydrogenation of this biobased succinic acid into biobased butanediol.
This fifth method therefore makes it possible to obtain 50% or 100% biobased PBS depending on the origin of the constituent elements.
Generally, the PBS copolymers are obtained by incorporating other unit(s), in particular diol(s) and dicarboxylic(s). Among these other units, mention is made of diethylene glycol, propoanediol, terephthalic acid, 2-methylsuccinic acid, ethylene succinate, butylene succinate, propylene succinate, butylene fumarate, butylene adipate, acetate and e-caprolactone units.
Advantageously, the aliphatic (co)polyesters used in the compositions according to the invention are selected from polybutylene succinate (PBS), poly(butylene succinate adipate) PBSA (obtained by condensation reaction of ethylene glycol and butanediol-1,4 (BDO) with adipic and succinic acids), poly(butylene succinate-co-lactate) (PBSL) and poly(butylene succinate-co-g-caprolactone) (PBSC). Aromatic and semi-aromatic polyesters and copolymers thereof, in particular polybutylene adipate terephthalate also referred to as polybutyrate (PBAT) and its copolymers. (Semi-)aromatic copolyesters are obtained by polycondensation between aliphatic diols,
diacids and aromatic units of the dicarboxylic type (such as furanedicarboxylic acid, ethylene terephthalate, 2,5-furan dicarboxylic acid, dimethyl terephthalate). For example, PBAT is obtained by the condensation reaction between 1,4-butanediol and a mixture of adipic and terephthalic acids.
The (semi-)aromatic (co)polyesters preferably used in the composition according to the invention are selected from polybutyrate or polybutylene adipate terephthalate (PBAT), poly(methylene adipate terephthalate) (PTMAT), and poly(butylene succinate adipate) terephthalate (PBSAT), preferably polybutyrate.
Other biopolyesters that can be used in the compositions according to the invention:
- PCL: Poly(e-caprolactone) synthesised by ring-opening polymerisation of €- caprolactone, lactone resulting from the oxidation of cyclohexanone.
Its biodegradation in vivo is very slow.
Three types of mechanisms are described in literature: anionic, which gives low molar masses, cationic and by coordination.
The latter is the most used.
- PTT: poly(trimethylene terephthalate) is a polymer based on propanediol-1,3 (PDO), of high molar mass, of semi-crystalline structure.
- PEA: polyethylene adipate formed from polyethylene glycol and adipic acid.
In the compositions according to the present invention, biobased biodegradable (co)polyesters are preferred.
In the compositions according to the present invention, biodegradable biobased (co)polyesters with an average molar mass ranging from 10% to 105 g/mol are preferred.
Advantageously, a chain extender agent is added to increase the molar mass of a biodegradable (co)polyester used in the compositions according to the invention.
Generally, it also makes it possible to increase the viscosity of the composition.
A chain extender agent has two functional groups capable of reacting with the carboxylic acid or alcohol functions of the biopolyesters.
Many chain extenders are used in polyesters to increase their molar mass, such as diepoxys and bisoxazolines, which react preferentially with carboxylic acid functions, and diisocyanates, biscaprolactams and dianhydrides, which react with alcohol functions.
The chain extender compound can be selected from the group consisting of a multifunctional epoxy compound.
Chain extender compounds are available under the trade name Joncryl® from BASF, possessing about 9 epoxy functions per mole and having a high reactivity with acid functions.
Preferably, the composition comprises from 0.1% to 0.5% by weight of chain extender compound relative to the total weight of the composition.
The structure of biodegradable (co)polyesters can also be modified by a solid grafting process or by reactive extrusion or derivatives of these processes, graft modified biodegradable (co)polyesters can be incorporated to said composition as a compatibility add-on or property modifier, preferably the quantity of biodegradable (co)polyesters modified by grafting ranges from 0.5% to 10% by weight relative to the total weight of the composition.
The grafting elements can be maleic anhydride, vinyl silane, glycidyl methacrylate, hydroxyethyl acrylate, methyl methacrylate, butyl acrylate, acrylic acid (...). The rate of grafting in the (co)biopolyester is generally between 0.5% and 5%. Depending on the intended applications, in particular for use in or near fresh or salt water or in an environment subject to bad weather, said biodegradable (co)polyester is selected from (co)polyesters that are stable under the usual conditions of use, for a period agreed in advance.
Finally, requirements of the "food compatibility” type can play a crucial role in the choice of components.
Rigid biodegradable (co)polyester The composition according to the present invention comprises from 40% to 90%, preferably from 50% to 90%, of at least one rigid biodegradable (co)polyester, relative to the total weight of the composition.
Said rigid biodegradable (co)polyester is selected from the group formed by polylactic acid, polyglycolic acid, polyhydroxyalkanoates, aliphatic polyesters, aromatic and semi- aromatic polyesters and copolymers thereof as well as copolymers thereof with poly(e- caprolactone). More particularly, the rigid biodegradable (co)polyester is selected from the lists mentioned above.
Advantageously, the rigid biodegradable (co)polyester is selected from the group formed by polylactide referred to as PLA, polyglycolide referred to as PGA and poly(lactic-co- glycolic acid) referred to as PLAGA, poly(3-hydroxybutyrate) referred to as P(3HB), poly(3-hydroxyvalerate) referred to as P(3HV), poly(3-hydroxyhexanoate), poly(3- hydroxyoctanoate), poly(3-hydroxynonanoate), poly(3-hydroxydecanoate), poly(3- hydroxyundecanoate), poly(3-hydroxydodecanoate), poly(3-hydroxyoctadecanoate), poly(5-hydroxybutyrate), poly(5-hydroxyvalerate), and copolymers thereof such as poly(hydroxybutyrate-co-hydroxyvalerate) referred to as PHBV, poly(3-hydroxybutyrate- co-3-hydroxyhexanoate) or P(3HB-co-3HHx) also referred to as P(3HB-3HH), polybutylene succinate referred to as PBS, poly(trimethylene terephthalate) referred to as PTT, poly (methylene adipate terephthalate) (PTMAT) and copolymers thereof.
Preferably, the rigid biodegradable (co)polyester is selected from the group formed by polylactide referred to as PLA, polyglycolide referred to as PGA, poly(lactic-co-glycolic acid) referred to as PLAGA, poly(3-hydroxybutyrate) referred to as P(3HB), poly(3- hydroxyvalerate, poly(hydroxybutyrate-co-hydroxyvalerate) referred to as PHBV, poly (3- hydroxybutyrate-co-3-hydroxyhexanoate) or P(3HB-co-3HHx) also referred to as P(3HB- 3HH), polybutylene succinate referred to as PBS, poly(trimethylene terephthalate) referred to as PTT, poly(methylene adipate terephthalate) (PTMAT). Preferably, a chain extender agent is added to increase the molar mass of the rigid biodegradable (co)polyester used in the compositions according to the invention.
Advantageously, the average molar mass of the rigid biodegradable (co)polyester ranges from 10% to 105 g/mol.
Flexible biodegradable (co)polyester(s) The composition according to the present invention comprises from 10% to 49% by weight of at least one flexible biodegradable (co)polyester relative to the total weight of the composition.
Said flexible biodegradable (co)polyester is selected from the group consisting of plasticised polylactide, plasticised polyglycolide and plasticised poly(lactic-co-glycolic acid), polyhydroxyalkanoates, aliphatic polyesters, aromatic and semi-aromatic polyesters, poly(e-caprolactone) and copolymers thereof. "Plasticised" polymer means a polymer comprising from 5% to 15% by weight of a plasticiser relative to the total weight of the composition consisting of the polymer and the plasticiser.
Preferably, the plasticiser is selected from the following compounds: triacetin, glucose, urea, diethanolamine, sebacates and derivatives thereof, adipates and derivatives thereof, glycols and derivatives thereof, polysuccinate, polyadipate and polysebacate of ethylene glycol, epoxidised oils.
More particularly, the flexible biodegradable (co)polyester is selected from the lists mentioned above.
Advantageously, the flexible biodegradable (co)polyester is selected from the group formed by plasticised polylactide, plasticised polyglycolide and plasticised poly(lactic-co- glycolic acid), polyhydroxyalkanoates with a medium length side chain, i.e. ranging from 3 to 13 carbon atoms, poly(3-hydroxypropionate) or P(3HP), poly(4-hydroxybutyrate) or P(4HB), plasticised poly(5-hydroxyvalerate), poly(3-hydroxybutyrate-co-3- hydroxyhexanoate) or P(3HB-co-3HHx) also referred to as P(3HB-3HH), poly(3-
hydroxybutyrate-co-3-hydroxyoctanoate) or P(3HB-co-3HO), poly(3-hydroxybutyrate-co- 4-hydroxybutyrate) also referred to as P3HB4HB, polybutylene succinate and its copolymers such as poly(butylene succinate adipate) referred to as PBSA, poly(butylene succinate-co lactate) referred to as PBSL, polybutylene adipate-co-terephthalate, poly(butylene succinate-co-t-caprolactone) referred to as PBSC, polybutylene adipate terephthalate or polybutyrate referred to as PBAT, poly(methylene adipate terephthalate) referred to as PTMAT, poly(butylene succinate adipate) terephthalate referred to as PBSAT, polyethylene adipate, (PEA), as well as poly(g-caprolactone). Preferably, the flexible biodegradable (co)polyester is selected from the group formed by plasticised polylactide, plasticised polyglycolide and plasticised poly(lactic-co-glycolic acid), poly(3-hydroxypropionate) or P(3HP), poly(4-hydroxybutyrate) or P(4HB), poly(3- hydroxybutyrate-co-3-hydroxyhexanoate) or P(3HB-co-3HHx) also referred to as P(3HB- 3HH), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) or P(3HB-co-3HO), poly(3- hydroxybutyrate-co-4-hydroxybutyrate) also referred to as P3HB4HB, polyhydroxyalkanoates with a medium length side chain, i.e., ranging from 3 to 13 carbon atoms, polybutylene succinate and its copolymers such as poly(butylene succinate adipate) referred to as PBSA, poly(butylene succinate-co lactate) referred to as PBSL, polybutylene adipate-co-terephthalate, poly(butylene succinate-co-¢-caprolactone) referred to as PBSC, polybutylene adipate terephthalate or polybutyrate referred to as PBAT, poly(methylene adipate terephthalate) referred to as PTMAT, poly(butylene succinate adipate) terephthalate referred to as PBSAT, polyethylene adipate (PEA), as well as poly(e-caprolactone). Preferably, a chain extender agent is added to increase the molar mass of the flexible biodegradable (co)polyester used in the compositions according to the invention.
Advantageously, the molar mass of the flexible biodegradable (co)polyester(s) ranges from 10% to 105 g/mol.
Some biodegradable (co)polyesters can be considered flexible or rigid depending on their composition or the (co)polyesters they are used with.
The first group of (co)polyesters corresponding to this definition are the copolyesters whose rigidity modulus and/or elongation at break will vary according to the proportion of the monomers present.
By way of example, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or PHBH is classified among rigid biodegradable (co)polyesters when the 3-hydroxybutyrate/3- hydroxyhexanoate ratio > 9; whereas it is classified among flexible biodegradable (co)polyesters when the 3-hydroxybutyrate/3-hydroxyhexanoate ratio <9.
The second group of (co)polyesters corresponding to this definition of copolyesters are copolyesters having a rigidity modulus between 500 and 850 MPa and an elongation at break between 100% and 300%. By way of example, mention may be made of polybutylene succinate or PBS.
When a composition according to the invention comprises a biodegradable copolyester having a rigidity modulus between 500 and 850 MPa and an elongation at break between 100% and 300%, then it also contains either at least one copolyester having a rigidity modulus greater than 850 MPa and an elongation at break of less than 100% or at least one copolyester having a rigidity modulus of less than 500 MPa and an elongation at break greater than 300%. According to a first variant, the composition comprises a (co)polyester having a rigidity modulus between 500 and 850 MPa and an elongation at break between 100% and 300% and a rigid (co)polyester having a rigidity modulus greater than 850 MPa, and an elongation at break of less than 100%. According to a second variant, the composition comprises a (co)polyester having a rigidity modulus between 500 and 850 MPa and an elongation at break between 100% and 300% and a flexible (co)polyester having a rigidity modulus of less than 500 MPa, and an elongation at break greater than 300%. Preferably, the composition according to the invention is such that the rigid biodegradable (co)polyester is polybutylene succinate and the flexible biodegradable (co)polyester is chosen from the group consisting of poly(butylene succinate adipate) terephthalate, polybutyrate or polybutylene adipate terephthalate, poly(butylene succinate adipate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-4- hydroxybutyrate), medium length side chain polyhydroxyalkanoates, i.e., ranging from 3 to 13 carbon atoms, poly(3-hydroxypropionate), poly(4-hydroxybutyrate); or the rigid biodegradable (co)polyester is polylactide and the flexible biodegradable (co)polyester is chosen from the group consisting of polybutylene succinate, poly(butylene succinate adipate) terephthalate, polybutyrate, poly(butylene succinate adipate), poly(3- hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), medium length side chain polyhydroxyalkanoates, i.e., ranging from 3 to 13 carbon atoms, poly(3-hydroxypropionate), poly(4-hydroxybutyrate); or the rigid biodegradable (co)polyester is selected from the group consisting of poly(3-hydroxybutyrate), poly(3- hydroxyvalerate), poly(hydroxybutyrate-co-hydroxyvalerate) and poly(3-hydroxybutyrate- co-3-hydroxyhexanoate) and the flexible biodegradable (co)polyester is selected from the group consisting of polybutylene succinate, poly(butylene succinate adipate)
terephthalate, polybutyrate, poly(butylene succinate adipate), poly(3-hydroxybutyrate-co- 3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), medium length side chain polyhydroxyalkanoates, i.e., ranging from 3 to 13 carbon atoms, poly(3- hydroxypropionate), poly(4-hydroxybutyrate). According to a first preferred mode, the composition according to the invention is such that the rigid biodegradable (co)polyester is polybutylene succinate (PBS) and the flexible biodegradable (co)polyester is polybutyrate or polybutylene adipate terephthalate (PBAT). Advantageously, said composition comprises from 60% to 80%, preferably from 65% to 75% and advantageously approximately 70% by weight of rigid biodegradable (co)polyester relative to the total weight of the composition and from 20% to 40%, preferably from 25% to 35% and advantageously 30% of flexible biodegradable (co)polyester by weight relative to the total weight of the composition.
According to a second preferred mode, the composition according to the invention is such that the rigid biodegradable (co)polyester is polylactide and the flexible biodegradable (co)polyester is polybutylene succinate.
Advantageously, said composition comprises from 69% to 88% and advantageously approximately 88% by weight of rigid biodegradable (co)polyester relative to the total weight of the composition and from 10% to 30%, and advantageously approximately 10% of flexible biodegradable (co)polyester by weight relative to the total weight of the composition.
Vinyl polymer The composition according to the present invention comprises from 0.5% to 10%, preferably from 1% to 5%, and more preferably from 1% to 3% by weight of a vinyl polymer relative to the total weight of the composition.
The composition according to the invention advantageously comprises 1%, 2%, 3%, 4% or 5% by weight of a vinyl polymer.
This vinyl polymer can also be grafted.
Advantageously, said vinyl polymer is selected from polyvinyl acetate, grafted polyvinyl acetate, ethylene polyvinyl acetate (vinyl ethylene-acetate copolymers) referred to as PVAc and grafted ethylene polyvinyl acetate, preferably said vinyl polymer is polyvinyl acetate. “Grafted vinyl polymer” means that the vinyl polymer is modified by grafting, preferably with at least one agent selected from the group consisting of maleic anhydride, glycidyl methacrylate, hydroxyethyl acrylate, methyl methacrylate, butyl acrylate, acrylic acid, preferably maleic anhydride and glycidyl methacrylate.
Advantageously, the composition according to the invention is biodegradable.
According to a preferred variant, the composition according to the invention comprises from 67% to 73% by weight of PBS, 27% to 33% by weight of PBAT and 1%, 2% or 3% by weight of polyvinyl acetate.
According to another preferred variant, the composition according to the invention comprises from 69% to 88% by weight of PLA, 10% to 30% by weight of PBS and 1%, 2% or 3% by weight of grafted ethylene polyvinyl acetate.
The article according to the invention may have a service life ranging from 1 to 10 years, preferably from 1 to 5 years.
Of course, the service life will be adapted according to the application, the stress and the application environment, which can be terrestrial, mountainous, marine, lacustrine, tropical, Mediterranean, temperate.
The service life is adapted according to the choice of biodegradable (co)polyesters and optionally additives.
Depending on the intended applications, in particular for uses in or near fresh or salt water or in an environment subject to bad weather, the composition according to the invention is advantageously water-stable.
Thus, it is important that said composition exhibits relative stability in water depending on the intended uses.
Likewise, it is important that said composition exhibits relative stability to ultraviolet rays.
In addition, to solve the problem posed at the origin of the invention, the biodegradable (co)polyesters used in the compositions must meet requirements in terms of difference in melting temperatures and melt flow index (MFI). The expression MFI is used below.
Thus, in the compositions according to the invention, the biodegradable (co)polyesters are selected such that the difference in melting temperatures between the two biodegradable (co)polyesters having the greatest difference in melting temperatures is less than 25 °C, preferably below 15 °C, more preferably below 10 °C.
In particular, when the composition according to the invention comprises two biodegradable (co)polyesters, the difference in melting temperatures between the two biodegradable (co)polyesters is less than 25 *C, preferably less than 15 *C, preferably less than 10 *C.
The difference in melt flow indices between the two biodegradable (co)polyesters having the greatest difference in melt flow indices (MFI) is less than 5 g/10 min, preferably less than 3 g/10 min.
In addition, in the compositions according to the invention, the biodegradable (co)polyesters are advantageously selected such that each has a melt flow index (MFI) ranging from 1 to 7 g/10min for monofilament extrusion-spinning, extrusion-film, extrusion-blowing, extrusion-flaconising; or ranging from 20 to 50 g/10min for multifilament extrusion-spinning, extrusion-spunbond (this technology being specific to nonwoven fabrics). In particular, when the composition according to the invention comprises two biodegradable (co)polyesters, the difference in the melt flow indices of these two biodegradable (co)polyesters is less than 5 g/10 min, preferably less than 3 g/10 min.
Additives The composition according to the present invention comprises from 0% to 5% by weight of at least one other (co)polyester in the form of powder or granules.
The biodegradable (co)polyesters used in powder form in the composition according to the invention are advantageously selected from the group formed by polylactic acid, polyglycolic acid, polyhydroxyalkanoates and copolymers thereof; aliphatic polyesters, in particular polybutylene succinate, aromatic and semi-aromatic polyesters as well as poly(e-caprolactone) and copolymers thereof, in particular polybutyrate or polybutylene adipate terephthalate and copolymers thereof.
The composition according to the present invention advantageously comprises at least one other polymer, different from (co)polyesters, selected from biobased and/or biodegradable and/or compostable addition polymers.
The other polymer referred to as "addition polymer” is advantageously selected from (agro)polymers of the polysaccharide family such as alginate, chitin, chitosan, cellulose, optionally plasticised starch or derivatives thereof, from the family of proteins such as casein, gelatin, ceratin, gluten or derivatives thereof.
Preferably, the other polymer is selected from alginate, chitin, cellulose, starch, casein.
The composition may comprise from 0% to 20% of at least one other polymer other than (co)polyesters, by weight relative to the total weight of the composition.
The composition according to the invention can also comprise pigments, preferably in an amount of less than or equal to 1% by weight.
The pigments are selected from mineral pigments, organic pigments, natural pigments derived from dyeing plants, they have a colouring strength, opacity, resistance to UV ageing, bad weather, industrial nuisances, migration that are acceptable for the desired applications.
Preferably the pigments are biobased.
The composition according to the invention can also be coloured on the surface by means of a liquid dye.
Advantageously, the articles according to the invention are coloured on the surface by means of a liquid dye.
Said liquid dye is then used in an amount of less than or equal to 2% by weight relative to the total weight of the composition.
Preferably the liquid dyes are biobased.
They have a colouring strength, an opacity, and a resistance to UV ageing, bad weather, industrial nuisances, migration that are acceptable for the desired applications.
The composition according to the present invention advantageously comprises at least one additive selected from the group formed by a chain extender compound, a grafting agent, a mineral reinforcement, a vegetable reinforcement, a reinforcement of animal origin, a fatty acid, a compound flame retardant, an anti-ultraviolet compound, an anti- bacterial compound, an anti-oxidant compound, an anti-fungal compound, an agent for improving organoleptic properties, a lubricating agent, a dispersing agent, a plasticiser.
Preferably, the composition according to the invention comprises at least one additive selected from the group formed by anti-bacterial, anti-oxidant, anti-fungal agents, an anti- ultraviolet compound, a flame retardant compound.
Advantageously, the additives selected are not subject to any specific regulations.
Of course, each of the additives is introduced into the composition according to the invention in an amount such that it does not alter its properties.
Preferably, each of the additives is used in an amount of less than or equal to 1% by weight relative to the total weight of the composition and the total content of additives in the composition according to the invention is less than or equal to 10%, preferably to 5% by weight relative to the total weight of the composition.
These additives can also be used in surface treatment, generally in an amount of less than or equal to 2% by weight relative to the total weight of the composition.
These treatments make it possible to improve the thermal, mechanical, antibacterial, antioxidant, anti-fungal, anti-UV, anti-fire and hydrophobic properties of the articles prepared from the composition according to the invention.
These additives are selected according to the intended applications and make it possible to give the articles prepared from the composition according to the invention good resistance to salinity, to hydrolysis, to exposure to ultraviolet rays and, to a lesser extent, to fungi and bacteria present in so-called “aggressive” environments.
The chain extender compounds and the grafting agents have already been defined above.
The mineral or plant reinforcements generally have a particle size of less than 50 um, preferably less than 10 um, very preferably between 1 and 0.5 um.
Said mineral reinforcement can be oyster shell powder of the Crassostrea genus, preferably Crassostrea gigas oyster shell powder.
Said mineral reinforcement can also be ground cuttlefish bone powder of the giga cephalopod class.
Said mineral reinforcement can also be poultry eggshell powder, preferably from Gallus gallus domesticus such as hens.
The mineral reinforcement can also be a geological mineral filler, such as for example talc or wollastonite.
The composition may comprise from 0% to 10% of said additional mineral reinforcement, by weight relative to the total weight of the composition.
The plant reinforcement can be fruit powder and/or the shell from a plant of the Fagaceae family such as Castanea or Quercus, said vegetable reinforcement can be selected from acorns, chestnuts or horse chestnuts.
The plant reinforcement can come from arthrospira such as spirulina or from eukaryotic or prokaryotic microalgae.
The plant reinforcement can be selected from natural plant fibres, in particular short bamboo, flax, hemp, jute, miscanthus, wood, milkweed or cellulosic fibres with a length of less than 50 um.
The composition may comprise from 0% to 10%, preferably from 0% to 2%, of said plant reinforcement by weight relative to the total weight of the composition.
The reinforcement of animal origin may be fibres obtained from molluscan byssus.
The composition may comprise from 0% to 10%, preferably from 0% to 2%, of said fibres derived from mollusc byssus, by weight relative to the total weight of the composition.
Said fibres derived from mollusc byssus can be derived from the byssus of mussels, preferably from the byssus of Mytilus edulis.
The fatty acid can be selected from the group consisting of unsaturated fatty acids; preferably from the group of polymerised unsaturated fatty acids; very preferably from the group consisting of dimers of unsaturated fatty acids, trimers of unsaturated fatty acids, and mixtures thereof.
These fatty acids have carboxylic acid groups as terminal reactants.
The fatty acids marketed under the name Pripol™ are produced from the transformation of natural fatty acids.
The longer the side alkyl chain, the greater the surface hydrophobicity.
Pripol 1009F® by Croda can be selected for its long alkyl chain with 36 carbon atoms, increasing the hydrophobicity of the hydrophilic biopolyester and therefore making it possible to further reinforce its water resistance and limiting the hydrolysis of the composition.
The fatty acid must be added in adequate proportions so as not to affect the mechanical properties of said composition.
The composition may comprise 0% to 10%, preferably 0% to 3%, of a fatty acid by weight relative to the total weight of the composition.
The flame retardant compound is preferably biobased; it can be selected from the group consisting of polymers derived from furfural, itself derived from hemicellulose (example: xylose). The composition may comprise from 0% to 2%, preferably from 0.2% to 1%, of said flame retardant compound, by weight relative to the total weight of the composition.
The anti-ultraviolet (UV) agent can be selected from the group consisting of a heterocyclic nitrogen, available under the trade name CYASORB® by Solvay, benzotriazoles available under the name Chiguard from Chitec, titanium dioxides, zinc dioxides.
The composition may comprise from 0.1% to 3% of said anti-UV agent, by total weight of the composition.
The agent for improving organoleptic properties can be selected from the group consisting of a shine agent, a whitening agent, respectively of the calcium carbonate type.
The composition may comprise from 0% to 5%, preferably from 0% to 1%, of said agent for improving organoleptic properties, by weight relative to the total weight of the composition.
The lubricating agent allows a reduction in the coefficient of friction of the materials on the surface of the screw sheath and therefore a reduction in pressure in the extrusion system.
During the melting phase, the lubricating agent migrates to the surface of the material where it forms a lubricating layer.
It improves the quality of the mixture and reduces the risk of degradation of the bioplastics.
Croda's IncroMax 1002 could be selected for its plant origin.
The composition may comprise from 0.2% to 0.3% of said lubricating agent, by total weight of the composition.
The dispersing agent allows the pigments and various reinforcements or other additives to be dispersed and therefore improves the quality of the mixture, its homogeneity and its processability.
BYK-P 4102 by BYK could be selected.
The composition may comprise from 0.5% to 2% of said dispersing agent, by total weight of the composition.
The plasticiser allows a reduction in the glass transition temperature or in the degree of crystallinity of the biopolyester or its copolymers and therefore reducing the rigidity of the material.
The plasticiser is selected according to the biopolyesters used in the mixture.
The composition may comprise 1% to 15% of said plasticiser.
Preparation method The composition according to the invention can be manufactured by a method implementing a step selected from the group formed by extrusion-spinning, extrusion- calendering, extrusion-foaming, profile extrusion, extrusion-blowing, extrusion-filming, extrusion-spunbond or all derivatives of these methods.
As already mentioned, the method for preparing the composition according to the invention comprises a step of extrusion-spinning by melting using a twin-screw extruder.
The twin-screw extruder has several feed hoppers along its sheath and an alternation between conveying, mixing and holding profiles along the twin-screw in order to obtain a mixture that is as homogeneous as possible at the die outlet.
Among the key parameters is the temperature gradient in the sheath, generally selected between the melting temperature of the polymer with the highest melting point used +15 °C and the thermo- degradation temperatures of the raw materials and the flow rate, which must not be either too low (to avoid the materials staying too long in the sheath and consequently experiencing thermo-degradation) or too high (to avoid too high a shear rate and consequently thermo-mechanical degradation or to avoid staying too little in the sheath, which would alter the quality and homogeneity of the composition).
It is within the competence of a person skilled in the art to adjust these parameters in order to optimise the quality and homogeneity of the composition.
Preferably, said composition is manufactured by a method comprising the following steps:
- having at least one rigid biodegradable (co)polyester, at least one flexible biodegradable (co)polyester, and at least one vinyl polymer,
- in the main hopper of a twin-screw extruder, pre-dosing and incorporating the rigid and flexible biodegradable (co)polyesters as well as the optional compounds selected from the group formed by addition polymers in the form of granules, the lubricating agent or other processing aids in the form of granules;
- in a rear hopper positioned after the main hopper along the twin-screw extruder, pre-dosing and incorporating the vinyl polymer in powder form and optionally the other additives selected from the group formed by addition polymers in powder form, flame retardant compounds, anti-ultraviolet compounds, anti-bacterial compounds, anti-fungal compounds, agents for improving organoleptic properties, lubricating agents, dispersing agents in powder form;
- optionally pre-dosing and incorporating the mineral or plant or animal reinforcements in the form of micronised powder in a hopper positioned between the main hopper and the “rear” hopper along the twin-screw extruder;
- optionally pre-dosing and incorporating the agents in liquid form selected from the group formed by fatty acids, anti-ultraviolet compounds, antibacterial compounds, anti-fungal compounds, organoleptic properties improving agents, lubricating agents in a hopper suitable for liquids,
- recovering the composition according to the present invention.
Of course, the components are pre-dosed so as to obtain a composition comprising quantities of rigid and flexible biodegradable (co)polyesters and vinyl polymer according to the present invention.
The composition according to the invention has good spinnability, and makes it possible to obtain articles that have remarkable strength.
The spinnability criterion is defined in relation to the winding times of a monofilament in a process of implementation by extrusion spinning in the laboratory until it breaks; this criterion is generally weighted in relation to the results of an industrially validated composition.
On average, 5 to 10 tests are carried out once the extrusion-spinning parameters have been optimised.
In addition, it has been observed that the processing temperature (extrusion) of the composition according to the invention is lower than those of conventional plastics of the HDPE, PET, PP type: reductions in heating temperatures from 20 to 135 °C have been obtained.
Consequently, another advantage of the method for preparing the composition according to the invention is that it makes it possible to reduce the heating time of the extruder.
For example, the conforming composition A exemplified is implemented between 145 and 170 °C, whereas conventional plastics are extruded between 190 and 280 °C.
Said composition according to the invention allows a reduction in the energy consumption of the machine and therefore, a reduction in its environmental impact.
Articles The composition according to the invention is advantageously used for the eco-design of articles.
The article according to the invention is obtained from biodegradable polymers.
Therefore, a first advantage is that it can itself be biodegradable and/or recyclable at the end of its life, in particular under certain conditions depending on the quality of the material and thus, being part of an eco-design approach, i.e., the judicious choice of materials that are biodegradable and recyclable under certain conditions, advantageously biobased, the recovery of local co-products (i.e., waste), the reduction in energy consumption during processing, considerably reducing the environmental impact of articles based on said composition compared to articles based on oil-based and non- biodegradable plastics.
The reduction in environmental impact is calculated by life cycle analysis (LCA) according to standard ISO 14040. Thus, the present invention is also aimed at an article obtained from a composition according to the present invention, selected from the group formed by threads, monofilaments, multifilaments, fibres, cosmetic hair, horsehair, nets in particular for fishing gear and/or food, ropes, braids, woven fabrics, nonwoven fabrics, blown structure-
blown, films, tube profiles.
The article according to the present invention is advantageously biodegradable and even more preferably compostable.
In addition, these properties allow easier manufacture of the compositions and corresponding articles, with acceptable or improved mechanical and thermal properties and ensure their biodegradability, their compostability and possibly their recyclability.
The inventors estimate the biodegradation of articles obtained from said composition according to the invention such as composition A at a period ranging from 5 to 30 years depending on the degradation medium and climatic variability.
The biodegradation mechanisms can be biotic under the action of micro-organisms (enzymatic hydrolysis, enzymatic oxidation, degradation by organic acids, etc.) or abiotic, depending on the medium (acid-base hydrolysis, oxidation, photodegradation, thermodegradation, acid- base reaction of substrates, etc.) Furthermore, the articles according to the invention can in very specific conditions such as a hot and humid environment, of the industrial compost type (EN 13432, EN 14995), degrade much more quickly, about 90% biodegraded in 6 months.
Thus reducing landfill congestion problems.
These articles are distinguished by their remarkable physical properties in terms of toughness, breaking strength, rigidity, thermal resistance, abrasion resistance.
In particular, the composition according to the invention is advantageously used for producing monofilament articles and fibres: the filament obtained is solid: it does not have any necking defects along its section (variation in diameter due to non-uniform stretching). Preferably, said monofilament or fibre type article according to the invention has a diameter ranging from 0.1 mm to 1 mm.
Said monofilament is advantageously biodegradable and even more preferably compostable.
In particular, said monofilament is intended for application in geotextiles, in particular for the fishing sector, ropes, cosmetics, woven fabrics and nonwoven fabrics for textiles, compounds, medical, hygiene, construction, food.
Advantageously, the composition according to the present invention is used in or for the manufacture of fishing gear or geotextiles, which can in particular be used in the marine or seaside environment, in particular in fields such as shellfish farming or aquaculture.
The invention also relates to a method for preparing an article in which a composition according to the invention is subjected to a step of extrusion-spinning by melting.
Advantageously, the spinning extrusion step for preparing the article according to the invention is carried out using a single-screw extruder.
The single-screw extruder has a feed hopper and a single-screw conveyor for melting and conveying the material to the spinning die.
Among the key parameters of this step is the temperature gradient in the sheath, generally selected between the melting temperature of the polymer with the highest melting point used +15 °C and the thermo-degradation temperatures of the raw materials and the flow, which must be neither too low (to avoid the materials staying too long in the sheath and consequently experiencing thermo-degradation) nor too high.
In addition, the choice of the extruder outlet die is also very important since it will determine the shape of the section and partially the size of the filament that will be stretched.
It is within the competence of those skilled in the art to adjust these parameters in order to optimise the quality of the article.
Preferably, the monofilament or fibre article with a diameter of 0.1 mm to 1 mm according to the invention is manufactured by a method comprising the following steps:
- having a composition according to the invention in the form of granules,
- incorporating said composition into the main hopper of a horizontal single-screw extruder,
- at the outlet of the spinning die of the extruder, recovering the melted composition with a diameter ranging from 0.3 to 4 mm obtained in a cooling water tank with variable temperature between 0 and 100 °C and depth of immersion,
- driving the spun and cooled composition through a first roller bank rotating at a first speed v1,
- stretching the spun composition a first time through an oven (hot air, infrared or hot water, etc.) setting the stretching temperature Tr via a second roller bank rotating at a speed v2 greater than v1,
- optionally repeating the previous step one or more times;
- recovering the filament by winding.
The expression “by winding” means that the filament obtained is wound around a spool.
It is a matter of competence to optimise the rotation speeds of the rollers, in particular v1 and v2, the temperatures, in particular the stretching temperature TF, the stretching rate according to the desired mechanical properties of the article.
Advantageously, the article, in particular the monofilament, according to the present invention is biodegradable, preferably it is also compostable.
Uses
While being part of an environmentally friendly approach, the biodegradable article according to the invention has very satisfactory properties in terms of good strength under conditions of high salinity, high humidity, high bacteriological rate, prolonged exposure to ultraviolet rays, and/or temperature variations, in particular at temperature variations between -10°C and 80 °C. Thus, the article according to the invention can be used in the medical, marine, nautical, cosmetic, textile, geotextile, automotive, aeronautical, furniture, building fields. The article according to the invention has advantages at the end of its life. It can either be recycled if the composition meets the quality criteria according to a specific analysis protocol, allowing it to be used again for the production of the same article or other articles
(e.g.: nonwoven fabrics, plates, profiles, etc.), or be composted in industrial compost if the composition does not meet the quality criteria for recycling or those for composting. Depending on the applications, it has at least one of the following properties: suitability for contact with food, biocompatibility, medical approval, antibacterial, plastic grade adapted to the specific extrusion implementation process. The following examples are intended to illustrate the invention without limiting its scope. Examples Example
1. Compositions The polymers used in example | are presented in the following tables: Table 1 presents the characteristics of the PBS marketed under the name FZ91 by the company PTT MCC Biochem Company Ltd. PBS is used as a rigid biodegradable (co)polyester. Table 1: Characteristics of FZ91 by PTT MCC Biochem Company Ltd — Swan | wm | wm Breaking stress Mpa 47
Table 2 presents the characteristics of the PBAT marketed under the name Ecoflex by the company BASF.
PBAT is used as a flexible biodegradable (co)polyester.
Table 2: Characteristics of BASF Ecoflex ws Bates Table 3 presents the characteristics of the PVAc in the form of a powder marketed under the name Vinnex by the company WACKER.
Table 3: Features of WACKER Vinnex Gao [Um | Ju
Compositions
Compositions A (according to the invention) and B (for comparison) were prepared.
These compositions comprise the raw materials and proportions indicated in table 4 below.
Raw materials are expressed as a percentage (and part by weight) of the final compound.
Table 4: compounds and proportions (in % by weight relative to the final composition) maeja s = = Composition 69 29 2 34.5 100
A according to the Comparative 70 30 35 100 Composition mel. Composition preparation method The mixing is carried out by a twin-screw extrusion process according to the method described above. The composition is compounded (implemented) by twin-screw extrusion. The extruder used for the tests is a laboratory twin-screw mini-extruder. It comprises a twin-screw that rotates inside the cylindrical sheath, the temperature of which is regulated by heating and cooling systems. The function of the extruder is to convey the biodegradable (co)polyesters, vinyl polymer and the additives of said composition, to melt them, pressurise them and mix them in order to obtain a rod at the die outlet. The rod is subseguently cooled, then granulated in order to obtain said composition that will then be implemented by injection. For each composition, 1 kg of material was prepared. The adjustment of the temperatures of the different zones of the extruder was carried out in coherence with the phase change temperatures of the biopolymers and the degradation temperatures of said composition. Adjusting the screw speed inside the sheath made it possible to ensure good mixing of said composition by shearing without significantly degrading the material. These parameters are recorded in table 5. The PBS and the PBAT in the form of granules are pre-dosed and incorporated (together) into the main hopper of the rear twin-screw extruder (hopper 3). For the preparation of composition A according to the invention, the PVAc in powder form is pre-dosed and incorporated into a tertiary hopper along the twin-screw extruder. Table 5 presents the temperatures of each zone (hopper) and speeds (rate) of the composition. Table 5: Parameters of the laboratory twin screw extruder Composition A according to the invention was then also compounded by twin-screw extrusion using a pilot twin-screw, i.e., on an industrial scale according to the parameters given in table 6. Table 6: Parameters of the pilot twin screw extruder Ze | 7 A KAKI KA KA KAKA KIKKA Method for preparing a monofilament article A monofilament article was prepared from each of compositions A and B using a horizontal single-screw extruder according to the parameters presented in table 7. Table 7: Parameters of the pilot twin screw extruder = [m | =