WO2024056824A1

WO2024056824A1 - Enzyme-containing multilayer article having water barrier properties

Info

Publication number: WO2024056824A1
Application number: PCT/EP2023/075348
Authority: WO
Inventors: Vincent Legrand
Original assignee: Carbiolice
Priority date: 2022-09-14
Filing date: 2023-09-14
Publication date: 2024-03-21
Also published as: FR3139500A1; FR3139500B1

Abstract

The present invention relates to an enzyme-containing biodegradable multilayer article having water barrier properties.

Description

Title: ENZYMATED MULTILAYER ARTICLE HAVING PROPERTIES

WATER BARRIERS

Field of the invention

[1] The present invention relates to an article of biodegradable multilayer plastic material having water barrier properties, in which at least one of the layers contains PLA as a biodegradable polymer and enzymes capable of degrading it.

State of the prior art

[2] Biosourced and biodegradable articles are known, in particular single-layer or multi-layer articles, used in the field of bags, and in particular for the manufacture of plastic bags. These bags are particularly used for packaging food products, particularly fruits and vegetables.

[3] Mention will be made in particular of the articles described in patents and patent applications WO 2020/193770, WO 2007/118828, WO 2002/059202A1, WO 2002/059199, WO 2002/059198, WO 2004/052646, WO 2018/233888 , US 6,841,597, US 8,751,816, US 5,436,078, US 9,096,758, US 2009/324917 and CN 106881929. However, these articles do not have water barrier properties for food packaging applications.

[4] The process for producing an article comprising enzymes capable of degrading the polymers which constitute it, must both make it possible to preserve the enzymes during the preparation of said article, for example via mixtures with polymers which melt at temperatures which do not degrade said enzymes, and respect the constraints of physical properties.

[5] Improving, in a simple and economical manner, the water barrier property of an enzymatic biodegradable article is all the more difficult to obtain, as this must not be done to the detriment of the activity of the enzymes. on the degradation of degradable polyester.

[6] Consequently, it is necessary to propose solutions making it possible to improve the water barrier properties of a plastic article without harming its biodegradability, and in a simple, economical and efficient manner. [7] This objective, among others, is achieved by the new composition of the biodegradable multilayer article according to the invention which offers numerous advantages, in particular having water barrier properties.

[8] Indeed, the inventors have discovered that a particular mixture of polymers makes it possible to improve the water barrier properties of a multilayer article made of biodegradable plastic material comprising enzymes and to respect the constraints of physical properties of the articles shaped with this mixture.

Summary of the invention

[9] The invention relates to a biodegradable multilayer article of type AB, AB A, ABC, BAB, BAC, ABCA BACB, BCACB or ACBCA, in which: the composition of layer A comprises at least PHA (polyhydroxyalkanoate) in one quantity less than 60% and PLA (polylactic acid); the composition of layer B comprises at least one thermoplastic polymer; and the composition of layer A and/or layer B comprises at least 0.001% of enzymes capable of degrading said PLA; the percentages being given by weight relative to the total weight of the composition of each layer.

[10] According to one embodiment of the invention, the polymer constituting layer B comprises at least one polyester chosen from polyesters such as PLA (polylactic acid), PBAT (polybutylene adipate terephthalate), PHA (polyhydroxyalkanoate ), PBS (polybutylene succinate), PCL (polycaprolactone), PBSA (polybutylene succinate adipate) and their mixtures in all proportions, preferably a mixture of PLA, PHA and PBAT.

[11] The article according to the invention relates to a flexible article made of plastic material, in particular a plastic film or a rigid article made of plastic material, in particular a sheet.

[12] The flexible article according to the invention preferably has a thickness ranging from 20 to 100 pm, preferably from 25 to 80 pm, more preferably from 30 to 60 pm, even more preferably from approximately 50 pm. [13] The rigid article according to the invention has a thickness of between 150 and 5000 pm, preferably between 400 and 500 pm, more preferably equal to approximately 450 pm.

[14] The invention also relates to a film comprising a multilayer article according to the invention, preferably, a flexible multilayer article according to the invention.

[15] The invention also relates to a sheet comprising a multilayer article according to the invention, preferably, a rigid multilayer article according to the invention.

[16] The multilayer article according to the invention can be used for the preparation of packaging, a lid, a cup, a plate, a beverage capsule, a tray or a packaging blister.

detailed description

Definitions

[17] This description will be better understood with reference to the following definitions.

[18] By multilayer thermoplastic article of type AB, ABA, ABC, BAB, BAC, ABCA, BACB, BCACB or ACBCA, we mean according to the invention an article whose layers are linked together and not simply associated by simple juxtaposition. In particular and preferably, the layers are linked by coextrusion. For example, the term ABA type article means an article comprising a central layer B framed by two adjacent layers A. The two layers A preferably have the same composition. According to certain embodiments of the invention, the multilayer article may comprise one or two layers C between layers A and B to provide particular properties to the articles according to the invention, more particularly to provide gas barrier properties and in particular to oxygen. For example, the article ABCA or ACBCA includes a layer C between the outer layer A and the central layer B.

[19] By “plastic article” according to the invention is meant any article made from at least one polymer, such as a sheet, film, tube, rod, profile, shape, solid block, fiber, etc. . in plastic material.

[20] The term “plastic film” or “plastic film” refers to a flexible plastic film (that is to say capable of being folded without breaking) with a thickness of less than 250 μm. Thin films are considered to have a thickness less than 100 pm and are preferably produced by blown film extrusion while thick films have a thickness greater than 100 pm and are preferably produced by cast film extrusion.

[21] According to the invention, the term “rigid article” or “rigid plastic article” refers to a plastic article which is not a film. These articles are preferably made by injection, thermoforming, blowing or even by rotational molding or 3D printing.

[22] As used herein, the term "masterbatch" means a concentrated mixture of selected ingredients (e.g., enzymes, additives, etc.) and a carrier polymer that can be used to introduce said ingredients into plastic articles in order to give them the desired properties. The masterbatch compositions allow the process to economically introduce selected ingredients during the plastic manufacturing process. Advantageously, the masterbatch is composed of a support polymer in which the selected ingredients are incorporated at high concentration. Typically, the masterbatch is intended to be mixed with one or more polymers or a polymer-based matrix to produce a final plastic article containing a desired quantity of selected ingredients. The masterbatch may also include mineral or organic fillers.

[23] Unless otherwise stated, percentages and relative ratios are expressed as mass relative to the total mass of the composition of the article.

[24] It is specified that the expressions "from...to..." and "between... and..." used in this description must be understood as including the limits mentioned. On the contrary, the expressions "greater than...", "less than...", "more than..." and "less than..." used in this description do not include the limits mentioned.

[25] In the context of the invention, the term "approximately" refers to a margin of +/- 5%, preferably +/- 1%, or within the tolerance of an appropriate measuring device or instrument .

[26] In the context of the invention, the expressions “layer A”, “layer B” and “layer C” are respectively interchangeable with the expressions “composition of layer A”, “composition of layer B” and “composition of layer C”.

Composition of the Articles

[27] The article according to the invention is a multilayer thermoplastic article of biodegradable plastic material of type AB, ABA, ABC, BAB, BAC, ABCA, BACB, BCACB or ACBCA, in which: the composition of layer A (also referred to as layer A in the present description) comprises at least PHA (polyhydroxyalkanoate) in an amount less than 60% and PLA (polylactic acid); the composition of layer B (also called layer B in the present description) comprises at least one thermoplastic polymer, preferably a polyester; and the composition of layer A and/or layer B comprises at least 0.001% of enzymes capable of degrading said PLA; the percentages being given by weight relative to the total weight of the composition of each layer.

[28] Without being bound by any theory, it appears that the PHA, present in the composition in an amount less than 60% by weight relative to the total weight of the composition of layer A with PLA and at least one polymer thermoplastic, exerts in an enzymatic multilayer article, an exacerbated water barrier function.

Composition of layer A:

[29] According to the invention, PHA (polyhydroxyalkanoate) polymers are biodegradable polymers and many of them are produced on an industrial scale by bacterial fermentation processes or isolated from plant materials such as corn , sweet potatoes, etc. PHA polymers can also be polycondensates of one or more hydroxyalkanoic acids. Examples of such hydroxyalkanoic acids which may be included in the PHA polymer are glycolic acid, hydroxypropanoic acid (also known as lactic acid), hydroxybutyric acid, hydroxyisobutanoic acid, hydroxypentanoic acid (also known as hydroxyvaleric acid), hydroxy hexanoic acid (also known as polycaprolactone, PCL), hydroxyheptanoic acid, hydroxyoctanoic acid, hydroxydecanoic acid, hydroxydodecanoic acid, hydroxytetradecanoic acid, or combinations of two or more thereof.

[30] Mention may be made, as examples, of PHAs such as PHBV (poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBH (poly3-hydroxybutyrate-co-3-hydroxy hexanoate), PHB ( poly-P-hydroxybutyrate), PHH (polyhydroxyhexanoate), P3HP (poly 3-hydroxypropionate), P3HB (poly 3-hydroxybutyrate), P4HB (poly 4-hydroxybutyrate), P4HV (poly 4-hydroxyvalerate), P5HV (poly 5- hydroxyvalerate), PHB3HP (poly 3- hydroxybutyrate-co-3-hydroxypropionate), P3HB4HB (poly 3-hydroxybutyrate- co-4-hydroxybutyrate), PHB4HV (poly 3-hydroxybutyrate-co-4- hydroxyvalerate), PHB3HV (poly 3 -hydro xybutyrate-co-3 -hydro xyvalerate), PHB3HH (poly 3 -hydro xybutyrate-co-3 -hydroxy hexanoate), PHB5HV (poly 3-hydroxybutyrate- co-5-hydroxyvalerate and their mixtures in all proportions. Preferably, the PHA is chosen from PHBV or PHBH.

[31] Advantageously, the PHA content in layer A is between 5% and 50%, preferably between 10% and 45%, more preferably between 20% and 40%, even more preferably between 20% and 35% in weight relative to the total weight of the composition of layer A. According to certain embodiments of the invention, the PHA content in layer A is equal to approximately 10%, 15%, 20%, 25%, 30% , 35%, 40%, 45% and 50% by weight relative to the total weight of the composition layer A.

[32] According to a preferred embodiment, the PHA content in layer A is equal to approximately 25% by weight relative to the total weight of the composition layer A.

[33] Advantageously, the PLA content in layer A is between 2% and 90% by weight, preferably between 3% and 80%, between 4% and 70%, between 5% and 60%, more preferably between 5% and 40%, even more preferably between 10% and 40% by weight relative to the total weight of the composition layer A.

[34] Layer A may comprise, in addition to PHA and PLA, complementary polyesters which are biodegradable polyesters well known to those skilled in the art. By complementary polyester we mean additional biodegradable polyesters different from PHA and PLA included in the composition of the layer. A. These “complementary polyesters” are chosen in particular from PBAT (polybutylene adipate terephthalate), PBS (polybutylene succinate), PCL (polycaprolactone), and PBSA (polybutylene succinate adipate), plasticized starch and their mixtures in all proportions.

[35] Preferably, the content of complementary polyesters in layer A is between 10% and 90% by weight, preferably between 20% and 80%, more preferably between 30 and 75%, even more preferably 40% and 70%. % by weight relative to the total weight of the composition layer A.

[36] According to a particular embodiment, the complementary polyester is PBAT.

[37] According to a preferred embodiment, layer A comprises a mixture comprising PHA, PBAT, the PBAT being the complementary polymer and PLA.

Composition of layer B:

[38] Layer B comprises one or more thermoplastic polymer(s) constituting this layer. According to a preferred embodiment of the invention, this constituent polymer(s) is one or more polyester(s) chosen from polyesters such as PLA (poly lactic acid), PBAT (polybutylene adipate terephthalate), PHA (poly hydroxy alkanoate), PBS (polybutylene succinate), PCL (polycaprolactone), PBSA (polybutylene succinate adipate) and their mixtures in all proportions.

[39] The constituent polymer(s) of layer B can also be chosen from barrier materials such as PVOH (poly vinyl alcohol), PVCD (poly vinyl chloride), PGA (poly glycolic acid). ), cellulose and its derivatives, or polysaccharides and their mixtures, used alone or in mixtures with the aforementioned polyesters.

[40] According to a particular embodiment of the invention, the polymer constituting layer B according to the invention is chosen from PLA, PHA, and PBAT and their mixtures in all proportions.

[41] According to a preferred embodiment, the polymers constituting layer B are a mixture of PLA, PBAT and PHA.

[42] According to another preferred embodiment, the polymers constituting layer B are a mixture of PLA and PBAT. [43] Advantageously, the PHA content, when it is present alone or in mixture with one or more other aforementioned polyesters in layer B, is as defined above for layer A. Preferably, the PHA content in layer B is equal to 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% and 55%, the percentages being expressed by weight relative to the total weight of the composition layer B.

[44] In a particular mode, the PHA content in layer B equal to 100% by weight relative to the total weight of the composition layer B.

[45] Advantageously, the PLA content, when it is present alone or mixed with one or more other aforementioned polyesters in layer B, is as defined above for layer A

[46] Advantageously, the PB AT content, when it is present alone or in mixture with one or more other aforementioned polyesters in layer B, between 5% and 95%, preferably between 20% and 80%, more preferably 40% and 75% by weight relative to the total weight of the composition layer B.

Layer A and/or layer B

[47] According to the invention, layer A and/or layer B comprises at least 0.001% by weight of enzymes capable of degrading the PLA of layer A and, where appropriate, of layer B, whether they are adjacent or separated by a layer C. It is understood that the enzyme content is expressed in weight relative to the total weight of the composition of layer A and/or B depending on whether the enzymes are present in layer A and/or layer b.

[48] The enzymes capable of degrading PLA used in the context of the present invention are well known to those skilled in the art. Mention will be made in particular of enzymes capable of degrading PLA so as to improve the biodegradability of the article according to the invention. Such enzymes and their mode of incorporation into thermoplastic articles are known to those skilled in the art, in particular described in patent applications WO 2013/093355, WO 2016/198652, WO 2016/198650, WO 2016/146540 and WO 2016/062695. Preferably these enzymes are chosen from proteases and serine proteases. In a particular mode, the serine proteases are chosen from Proteinase K from Tritirachium album, or PLA-degrading enzymes from Amycolatopsis sp., Actinomadura keratinilytica, Laceyella sacchari LP 175, Thermus sp., or Bacillus licheniformis or from enzymes commercial reformulated and known to degrade PLA such as Savinase®, Esperase®, Everlase® or any enzyme from the subtilisin family CAS 9014-01-1 or any functional variant.

[49] Those skilled in the art will adapt the enzyme content in layer A and/or layer B according to their objectives for degrading the PLA of layer A and/or B which surround it.

[50] Advantageously, the enzyme content in layer A and/or layer B will be at least 0.002%, more advantageously at least 0.05% by weight relative to the total weight of the composition of the layer. A and/or B. These contents can go up to 10% by weight relative to the total weight of the composition layer A and/or B, or even more. Although it is possible to formulate compositions comprising more than 10% of enzymes, it is nevertheless rare for such contents to be exceeded for the most frequent uses of the plastic articles according to the invention. Advantageously, the enzyme content in the composition of layer A and/or layer B is 0.01 to 7%, preferably 0.02 to 5% by weight relative to the total weight of the composition. layer A and/or B.

[51] According to a particular embodiment of the invention, the multilayer article comprises, by weight relative to the total weight of the composition of the article,:

10% to 35% PHA, preferably between 12.5 and 25% 10% to 50% PLA, preferably between 15 and 30% 50% to 60% PB AT, preferably between 52 and 56% at least 0.001% of enzymes capable of degrading said PLA and optionally, 0.8% to 8% of a support polymer such as PCL or PB SA, preferably 4%.

[52] According to a particular preferred embodiment of the invention, the article comprises, by weight relative to the total weight of the composition of the article:

10% to 35% PHA, preferably between 12.5 and 25% 10% to 50% PLA, preferably between 15 and 30% 50% to 60% PB AT, preferably between 52 and 56% 0.8% at 8% PCL, preferably 4% at least 0.001% enzymes capable of degrading said PLA. [53] According to another particular preferred embodiment of the invention, the article comprises, by weight relative to the total weight of the composition of the article:

10% to 35% PHA, preferably between 12.5 and 25%

10% to 50% PLA, preferably between 15 and 30%

50% to 60% PB AT, preferably between 52 and 56%

0.8% to 8% PBSA, preferably 4% at least 0.001% enzymes capable of degrading said PLA.

[54] According to the invention, layer A and/or layer B may further comprise usual additives used in the preparation of plastic articles, such as sliding agents, plasticizers, nucleating agents, compatibilizers, aids to manufacturing, UV radiation stabilizers, anti-shock agents, mineral or vegetable fillers, etc. According to a preferred embodiment, the usual additives are used in layer A of the article.

[55] Advantageously, the content of usual additives in the multilayer article according to the invention is at least 0.2%, preferably 1 to 5%, more preferably 2 to 4%, advantageously approximately 2 % by weight relative to the total weight of the composition of the article.

[56] According to a preferred embodiment, layer A and/or layer B of the multilayer article further comprises one or more slippery agents, such as oleamide, erucamide, stearamide, behenamide, oleyl palmitamide, stearyl erucamide, ethylene bisoleamide, EBS or a mixture thereof. Preferably, the slippery agent is oleamide.

[57] The article may also include plasticizers. The plasticizers used in the degradable plastic article are well known to those skilled in the art. They are chosen in particular from polyols and amides, lactic acid oligomers (OLAs) and citrate esters.

[58] OLAs are plasticizers known to those skilled in the art, in particular as biosourced materials. These are lactic acid oligomers with a molecular weight of less than 1500 g/mol. They are preferably esters of lactic acid oligomers, their carboxylic acid ending being blocked by esterification with an alcohol, in particular a linear or branched Cl -CIO alcohol, advantageously a C6-C10 alcohol, or a mixture of the latter. We will cite in particular the OLAs described in patent application EP 2256 149 with their method of preparation, and the OLAs marketed by the company Condensia Quimica under the brand Glyplast®, in particular the references Glyplast® OLA 2, which has a molecular weight of 500 to 600 g/ mol and Glyplast® OLA 8 which has a molecular weight of 1000 to 1100 g/mol. According to a preferred embodiment of the invention, the OLAs have a molecular weight of at least 900 g/mol, preferably from 1000 to 1400 g/mol, more preferably from 1000 to 1100 g/mol.

[59] Citrate esters are also plasticizers known to those skilled in the art as biosourced materials. Mention will be made in particular of triethyl citrate (TEC), triethyl acetyl citrate (TEAC), tributyl citrate (TBC), tributyl acetyl citrate (TB AC), preferably TB AC.

[60] Compatibilizers can be used in the composition of the multilayer article according to the invention. Such PLA/Polyester compatibilizers are well known to those skilled in the art, in particular molecules having epoxy, acrylate, anhydride, oxazoline and lactam functions which allow grafting reactions.

[61] Among the compatibilizers, we will particularly mention poly acrylates, terpolymers of ethylene, acrylic ester and glycidyl methacrylate (for example marketed under the brand Lotader® by the company Arkema), PLA- triblock copolymers. PBAT-PLA, maleic anhydride-grafted PLA (PLA-g-AM) or maleic anhydride-grafted PBAT (PBAT-g-AM).

[62] Mineral and/or vegetable fillers can also be used in the composition of the multilayer article of the invention, the mineral fillers preferentially used are calcium carbonate or talc.

[63] The vegetable fillers preferably used are starch and wood fibers and flour.

[64] Composition of layer C:

[65] The barrier materials constituting layers C are well known to those skilled in the art, and in particular PVOH (poly vinyl alcohol), EVOH (poly (vinyl alcohol-co-ethylen)), PVCD (polyvinyl chloride vinyl), PGA (polyglycolic acid), cellulose and its derivatives, or polysaccharides and their mixtures in all proportions, mentioned above for those which can also be used in the composition of layer A and/or layer B. [66] The PVOH used as a barrier material in the preparation of the article is well known. It is polyvinyl alcohol whose degree of polymerization is between 300 and 2500. Its melting point is below 210°C and its viscosity is between 3 and 60 mPa.s.

[67] The PVCD used as a barrier material in the preparation of the article is also well known. This is polyvinylidene chloride resulting from the copolymerization of vinylidene chloride (85%) and vinyl chloride (15%).

[68] The PGA used as a barrier material in the preparation of the article corresponds to polyglycolic acid whose melting temperature is 220°C and the glass transition temperature is 40°C.

[69] Among celluloses, we will particularly mention microfibrillated celluloses (MFC) and cellulose acetate.

[70] The MFCs used as barrier material have a diameter between 4 and 10006 nm and a density between 0.51 and 1.57 g/cm ³ .

[71] The polysaccharides used as barrier materials are also well known to those skilled in the art. Mention will be made more particularly of galactomannans, pectin or soluble soy polysaccharides, marine extracts such as carrageenans and alginates, and microbial or animal polysaccharides such as gellans, dextrans, xanthans, xylans or chitosan, and their mixtures.

[72] Advantageously, the rate of biosourced material to produce the article according to the invention is greater than 30%, preferably greater than 40%.

[73] As for layer A and/or layer B, layer C may also include usual additives in the preparation of plastic articles, as defined above.

[74] According to a preferred embodiment of the invention, the composition of layer C is as follows

90 to 100% barrier materials as defined previously, and

0 to 10% of additives, the percentages being expressed by weight relative to the total weight of the composition of layer C. [75] Preferably layer C comprises more than 95% by weight relative to the total weight of the composition of layer C of barrier material, even more preferably 99% or more.

[76] PVOH is a preferred barrier material for the C layers of articles according to the invention.

Items

[77] According to the invention, the plastic article is a manufactured product, such as rigid or flexible packaging, agricultural films, sachets and bags, disposable articles or the like. Preferably, the article is made of thermoplastic material. The plastic articles according to the invention may contain additional substances or additives, such as slippery agents, plasticizers, mineral or organic fillers.

[78] The multilayer article according to the invention advantageously has a thickness greater than or equal to approximately 20 μm, preferably greater than or equal to approximately 25 μm, more preferably greater than or equal to approximately 50 μm, more preferably greater than or equal to approximately 450 pm, more preferably greater than 750 pm, preferably less than 5000 pm.

[79] According to the invention, the plastic article can be chosen from a flexible plastic article or a rigid plastic article.

[80] According to one embodiment, the multilayer article according to the invention is a flexible article, in particular a plastic film.

[81] The multilayer flexible article according to the invention advantageously has a thickness less than 250 pm, preferably ranging from 20 to 100 pm, preferably from 25 to 80 pm more preferably from 30 to 60 pm, even more preferably from approximately 50 p.m.

[82] Examples of plastic films include agricultural films, plastic bags or bags, films for flexible packaging, food films, lids, packaging blisters, mailing films, routing films , mulching films, lining or covering films (called “liner films” in English), grouping films (called “multipack films” in English), industrial films, personal care films, nets, etc. [83] The multilayer article according to the invention also relates to a film comprising a flexible multilayer article, preferably a multilayer article as defined above.

[84] According to another embodiment, the multilayer article according to the invention is a rigid article.

[85] Examples of rigid plastic items are thin-walled packaging such as food and beverage packaging, boxes, trays, containers, food service items, electronic enclosures, cosmetic cases, outdoor gardening items such as pots, rigid packaging, containers, cups, plates, drink capsules, trays, packaging blisters, cards, cotton swabs, irrigation products pipes , etc. Certain rigid plastic articles can be produced by thermoforming plastic sheets with a thickness of 150 µm or more, such plastic sheets being produced by film casting or calendering.

[86] The rigid multilayer article according to the invention advantageously has a thickness greater than 150 pm, preferably less than 5000 pm.

[87] According to a preferred embodiment of the invention, the thickness of the multilayer article ranges from 150 to 3000 pm.

[88] The invention also relates to a sheet comprising a multilayer article according to the invention, preferably a rigid multilayer article as defined above.

[89] Advantageously, the thickness of the rigid multilayer article is less than 5000 pm, preferably between 400 and 800 pm, preferably between 400 and 500 pm, more preferably equal to approximately 450 pm. Alternatively, the thickness of the multilayer rigid article is equal to approximately 750 μm.

[90] According to certain preferred embodiments, the multilayer article is of type AB A or B AB. Preferably, the multilayer article is of type AB A.

[91] The relative thickness of each layer of the article AB, ABA, ABC, BAB, BAC, ABCA BACB, BCACB or ACBCA according to the invention can vary depending on the final properties sought for the article, particularly in terms of water barrier property but also in terms of biodegradability. According to one embodiment of the invention, the thickness of layer A or B is between 10 and 725 pm, between 18 and 30 pm, preferably equal to approximately 25 pm. [92] Advantageously, each layer A independently represents 5 to 30% of the total thickness of the article and the central layer B represents 40 to 90% of the total thickness of the article. Preferably, the central layer B represents 50 to 90% of the total thickness of the article.

[93] In a preferred embodiment of the flexible article of the invention, the two layers A have an identical thickness, each representing 15 to 30% of the total thickness of the article, preferably 16 to 25 %.

[94] In a preferred embodiment of the rigid article of the invention, the two layers A have an identical thickness, each representing from 2 to 20% of the total thickness of the article, preferably from 3 to 15 %.

[95] According to certain embodiments, the flexible multilayer article is of type AB, AB A, ABC, ABCA, ACBCA and in which each layer A represents 15 to 30% of the total thickness of the film and the central layer B represents 40 to 70% of the total thickness of the film.

[96] According to certain embodiments, the flexible multilayer article is of type AB, BAB, BAC, BACB, or BCACB and in which the layer B represents 15 to 30% of the total thickness of the film and the central layer A represents 40 to 70% of the total thickness of the film.

[97] The C layers, when present, generally have a thickness of less than 15 pm. They individually represent less than 15% of the total thickness of the item.

[98] According to a particular embodiment of the invention, the layers C, when present, of multilayer flexible articles have a thickness less than 3 pm. They individually represent less than 30% of the total thickness of the item.

[99] According to a particular embodiment of the invention, the layers C, when present, of rigid multilayer articles have a thickness less than 20 pm. They individually represent less than 30% of the total thickness of the item.

[100] The multilayer article of the invention can also be applied to a support of a different nature, such as a biodegradable film, paper or other. For example, the multilayer article of the invention can be glued by lamination to a biodegradable film to reinforce its water barrier properties.

Preparation of the article [101] Another object of the invention relates to a process for preparing a multilayer article according to the invention. The compositions of layers A, B and C are prepared by the usual techniques for preparing polymer compositions. The preparation of the articles is done by mixing the different constituents, then shaping the article according to the desired shape, flexible or rigid article.

[102] According to the invention, the enzymes having PLA degradation activity are added in an appropriate form to allow homogeneous dispersion of said enzymes in the multilayer article. These enzymes can be added directly to the polymers of layer A and/or layer B during its preparation, or in the form of a concentrated premix in a low melting point support polymer.

[103] According to a particular embodiment of the multilayer article according to the invention, the process comprises the following steps: a) Providing enzymes having polyester degradation activity in an appropriate form to allow homogeneous dispersion of said enzymes in the multilayer article, said form being chosen from

- a liquid composition comprising enzymes having PLA degradation activity, water and optionally a polysaccharide support, or

- a masterbatch comprising enzymes having PLA degradation activity and a support polymer having a melting temperature lower than 140°C and/or a glass transition temperature lower than 70°C, and b) the mixture of enzymes having a PLA degradation activity provided in step (a) with the polymers of layer A and/or layer B, and c) shaping of the article.

[104] A person skilled in the art will know how to prepare the multilayer article according to the invention, by all usual techniques which allow their connection, such as coextrusion, coinjection, lamination. Preferably, the article is prepared by coextrusion of the layers, the person skilled in the art being able to determine the conditions of implementation of the process, and in particular the mixture of the components entering into the composition of each layer. Advantageously, the coextrusion is carried out at a temperature below 200°C.

[105] According to a first embodiment, the enzymes are provided in the form of a liquid composition comprising enzymes having PLA degradation activity, water and optionally a polysaccharide support. Such liquid compositions and their use for the preparation of enzymatic polymer mixtures are described in particular in applications WO 2019/043145 and WO 2019/043134.

[106] The content of enzymatic composition in layer A and/or B will depend in particular on the content of enzymes in the enzymatic composition and the enzyme content sought for the article. According to a particular method, 1 to 10% by weight will be used relative to the total weight of the composition of the multilayer article.

[107] According to a second embodiment, the enzymes are provided by a master mix.

[108] The masterbatch is a concentrated premix of enzymes and a carrier polymer.

[109] The support polymer is a polymer having a melting temperature lower than 140°C and/or a glass transition temperature lower than 70°C.

[110] Polymers having a melting temperature below 140°C and/or a glass transition temperature below 70°C are well known to those skilled in the art. These are in particular polycaprolactone (PCL), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polyhydroxyalkanoate (PHA), polylactic acid (PLA), or their copolymers. It can also be a natural polymer such as starch or even a polymer that we would describe as universal, that is to say compatible with a wide range of polymers such as an EVA type copolymer. Advantageously, the support polymer has a melting temperature lower than 120°C and/or a glass transition temperature lower than 30°C.

[111] The support polymer is preferably chosen from PCL, PBSA, PBAT, PHA, PLA and their mixtures in all proportions, in particular PCL or even more preferably PBSA.

[112] Preferably, the masterbatch also comprises a polysaccharide. [113] The polysaccharides are chosen in particular from starch derivatives such as amylose, amylopectin, maltodextrins, glucose syrup, dextrins and cyclodextrins, natural gums such as gum arabic, gum tragacanth, gum guar, locust beam gum, karaya gum, mesquite gum, galactomannans, pectin or soluble soy polysaccharides, marine extracts such as carrageenans and alginates, and microbial or animal polysaccharides such as gellans, dextrans, xanthans or chitosan, and mixtures thereof. A preferred polysaccharide is gum arabic.

[114] In this case, the composition of the multilayer article according to the invention will also include a polysaccharide.

[115] A preferred masterbatch composition comprises from 50 to 95% of a low melting point polymer, in particular polycaprolactone (PCL) or even more preferably PBSA, preferably from 70 to 90%, from 0.001 to 10 % of enzymes, preferably from 1 to 6%, and from 1 to 30% of gum arabic, preferably from 10 to 25%, the percentages being expressed by weight relative to the total weight of the composition of the masterbatch.

[116] Such masterbatches and their preparation processes are described in particular in patent applications WO 2019/043134, WO 2021/148665 or in French patent application No. 2107809 filed on 07/20/2021.

[117] According to a particular embodiment of the invention, the article comprises: from 80 to 99% of constituent polymer, preferably from 90 to 99% from 0 to 40% of polysaccharide, preferably from 0.1 to 4% from 0 to 40% of a support polymer, preferably from 3 to 6% and from 0.005 to 10% of enzymes, preferably from 0.01 to 5%, more preferably from 0.01 to 3%, the percentages being expressed in weight relative to the total weight of the composition of the article.

[118] According to a more particular embodiment of the invention, the enzyme content in the above composition ranges from 0.02 to 1% by weight relative to the total weight of the composition of the article. [119] According to another embodiment, the article is prepared by shaping a premix or “compound” consisting of the composition of the article defined above.

[120] The premix is prepared according to the process described above, with granulation for step c) of shaping according to usual methods.

[121] The invention therefore also relates to a premix in the form of granules comprising: less than 60% of the PHA (polyhydroxyalkanoate),

- of PLA at least 0.001% of enzymes capable of degrading said polyester, and at least one complementary thermoplastic polymer, in all variants of embodiments described previously for the article, and the percentages being expressed by weight relative to the weight total composition of the premix.

[122] According to a particular embodiment, layer A and/or layer B comprises, in addition to the polymers which constitute it, enzymes, a support polymer and a polysaccharide as defined above.

[123] According to a particular embodiment of the invention, layer A or layer B consists essentially of the above enzymatic composition (the support polymer is also the constituent polymer). The composition can be supplemented by usual additives described above.

[124] According to a particular embodiment of the invention, the constituent polymer(s) of layer B according to the invention have a melting temperature lower than that of the constituent polymers of layer A.

Use of Articles

[125] The invention also relates to various uses of the multilayer articles obtained according to the invention, in particular flexible or rigid multilayer articles.

[126] The multilayer article according to the invention can be used for all usual uses of thermoplastic articles, and in particular for the preparation of packaging or bags, or even for mulching or routing. It can also be used for the preparation of disposable tableware (plates, glasses), packaging (trays, blisters) or drink capsules. [127] The different embodiments, variants, preferences and advantages described above for each of the objects of the invention apply to all the objects of the invention and can be taken separately or in combination.

[128] The invention is illustrated by the following examples given without limitation.

Examples:

[129] I. Preparation of a mix of support polymer and enzyme

[130] The mix of support polymer and enzyme is prepared from polycaprolactone (PCL) granules and the enzyme in liquid form as described in application WO 2019/043134.

[131] The mix of support polymer and enzyme was manufactured with a CLEXTRAL EV25HT twin-screw extruder comprising 11 zones for which the temperature is independently controlled and regulated. The PCL is introduced into zone 1 at 16 kg/h and the enzyme solution into zone 5 at 4 kg/h using a peristaltic pump. The zones are heated according to table [1]. 20% of the enzyme solution is introduced to the PCL (% by weight relative to the total weight).

Table 1: Temperature profile (°C) used for the polymer support and enzyme mix

[132] II. Commercial Products

[133] In these examples of PHBV sold under the reference ENMAT™ Y1000P by the company Helian Polymers, PHBH sold under the reference Green PLlanet™ X128 by the company KANEKA, PLA/PBAT mixtures sold under the references Ecovio® F2331, Ecovio ® F2332, Ecovio® F2223 and a slippery agent under the reference Ecoflex® SL-05 marketed by BASF, PLA marketed under the reference Luminy® LX175 by the company Total Corbion.

[134] III. Film production

[135] For the preparation of multilayer films, a Eurexma three-layer inflation coextrusion line is used, width 275 - 300 mm and screw L/D = 30. The rate of inflation was around 3.5 - 3.9. The settings and temperatures are detailed in tables [2] to [4].

Table 2: Process parameters for a 50pm film with a 25/50/25 A/B/A layer distribution

Table 3: Extruder process parameters

Table 4: Extruder process parameters

[136]VI. Analysis method

[137] The water barrier properties of the films were evaluated with a permeability test according to the following protocol: films measuring 30x8cm are folded in half lengthwise and welded on three ends to form a bag which is then filled with 20.0g of water. The bag is then sealed on its last side to form an airtight pocket and is laid flat for 7 days. The mass of the sachet is determined every day for a week in order to obtain an average water loss in g/d. [138] The evaluation of the biodegradability of the films was evaluated with a depolymerization test carried out according to the following protocol: 100 mg of each sample were introduced into a plastic vial containing 50 mL of buffer solution at pH 9.5. Depolymerization is started by incubating each sample at 45°C, in a shaken incubator at 150 RPM. An aliquot of ImL of buffer solution is taken regularly and filtered using a 0.22 µm filter syringe to be analyzed by high performance liquid chromatography (HPLC) with an Aminex HPX-87H column to measure the release. lactic acid (LA) and its dimer. The chromatography system used is an Ultimate 3000 UHPLC system (Thermo Fisher Scientific, Inc. Waltham, MA, USA) including a pump, an automatic sampler, a column thermostated at 50°C and a UV detector at 220nm. The eluent is 5 mM H2SO4. The injection is 20 pL of sample. Lactic acid is measured using standard curves prepared from commercial lactic acid.

[139] The hydrolysis of plastic films is calculated from the lactic acid and the lactic acid dimer released. The percentage of depolymerization is calculated after 7 days based on the percentage of PLA in the sample.

[140] Results

[141] VIL Film composition and results

[142] Type AB A films were prepared with the support polymer and enzyme mix prepared in I, PHA, PLA, and a mixture of PLA/PBAT.

[143] According to the examples below in accordance with the invention, the support polymer and enzyme mix prepared in I is present either in layers A, or in layer B or in layers A and B.

[144] The composition of the external A layers of films 11 to 17 also contain 2% of a slippery agent of the stearate type SL-05.

[145] The thickness of the films produced is 50 pm and the relative thicknesses of each layer A/B/A are 25%/50%/25%.

[146] The compositions of these different films are listed in table [5] below.

Table 5: The compositions of these different films produced

[147] Compositions with a PHA content above 60% were difficult to extrude to obtain multilayer films and present a very sticky appearance of the material which destabilizes the bubble and prevents the opening of the sheaths. [148] Film 10 is a comparative example.

[149] The properties of films 11 to 18 prepared above were measured according to the protocols defined above.

[150] The results of these measurements are given in Table 6 below.

Table 6: Results of measurements carried out

[151] It is thus demonstrated that the polymer mixture according to the invention leads to improved water barrier properties compared to a film without PHA. PHBV improves barrier properties in PLA/PHA blends more significantly than PHBH.

Claims

Claims Biodegradable multilayer article of type AB, AB A, ABC, BAB, BAC, ABCA BACB, BCACB or ACBCA, in which

- the composition of layer A comprises at least PHA (polyhydroxyalkanoate) in a quantity of less than 60% and PLA (polylactic acid);

- the composition of layer B comprises at least one thermoplastic polymer; And

- the composition of layer A and/or layer B comprises at least 0.001% of enzymes capable of degrading said PLA, the percentages being given by weight relative to the total weight of the composition of each layer. Multilayer article according to claim 1, characterized in that the thermoplastic polymers of the composition of layer B are polyesters chosen from PLA (polylactic acid), PB AT (polybutylene adipate terephthalate), PHA (polyhydroxyalkanoate), PBS ( polybutylene succinate), PCL (polycaprolactone), PBSA (polybutylene succinate adipate) and their mixtures. Multilayer article according to claim 1 or 2, characterized in that the PHA content in the composition of layer A is between 5% and 50% by weight, preferably between 10% and 45% by weight, more preferably between 20 % and 40%, even more preferably between 20% and 35% by weight relative to the total weight of the composition of layer A. Multilayer article according to any one of claims 1 to 3, characterized in that the PLA content in the composition of layer A is between 2% and 90% by weight, preferably between 3% and 80%, between 4% and 70%, between 5% and 60%, more preferably between 5% and 40% by weight. weight relative to the total weight of the composition of layer A. Multilayer article according to any one of claims 1 to 4, in which the composition of layer A further comprises complementary polyesters chosen from PBAT (polybutylene adipate terephthalate), the PBS (polybutylene succinate), PCL (polycaprolactone), PB SA (polybutylene succinate adipate), plasticized starch and their mixtures in all proportions. Multilayer article according to claim 5, in which the content of complementary polyesters is between 10% and 90%, preferably between 20% and 80%, more preferably between 30 and 75%, even more preferably 40% and 70% by weight , in relation to the total weight of the item. A multilayer article according to any one of claims 1 to 6, wherein layer A further comprises PB AT as complementary polyester. Multilayer article according to any one of claims 1 to 7, characterized in that it comprises, by weight relative to the total weight of the composition of the article: i. 10% to 35% PHA, preferably between 12.5 and 25% ii. 10% to 50% PLA, preferably between 15 and 30% iii. 50% to 60% PB AT, preferably between 52 and 56% iv. 0.8% to 8% PCL or PBSA, preferably 4% v. at least 0.001% of enzymes capable of degrading said PLA. Article according to the preceding claim, characterized in that it further comprises a polysaccharide. Multilayer article according to any one of claims 1 to 9, wherein the PHA is selected from the group consisting of PHBV (Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBH (poly3-hydroxybutyrate-co-3- hydroxyhexanoate), PHB (poly-P-hydroxybutyrate), PHH (poly hydroxy hexanoate), P3HP (poly 3-hydroxypropionate), P3HB (poly 3-hydroxybutyrate), P4HB (poly 4-hydroxybutyrate), P4HV ( poly 4-hydroxyvalerate), P5HV (poly 5- hydroxyvalerate), PHB3HP (poly 3-hydroxybutyrate-co-3- hydroxypropionate), P3HB4HB (poly 3-hydroxybutyrate-co-4- hydroxybutyrate), PHB4HV (poly 3 -hydroxybutyrate-co-4-hydroxyvalerate), PHB3HV (poly 3 -hydro xybutyrate-co-3 -hydro xy valerate), PHB3HH (poly 3 -hydro xybutyrate-co-3 -hydroxyhexanoate), PHB5HV (poly 3- hydroxybutyrate-co-5-hydroxyvalerate and their mixtures in all proportions. ZI Multilayer article according to any one of claims 1 to 10, characterized in that layer A and/or layer B further comprises at least one additive chosen from sliding agents, plasticizers, nucleating agents, compatibilizers, manufacturing aids, UV radiation stabilizers, anti-shock agents, mineral or vegetable fillers. Multilayer article according to claim 11, characterized in that the content of additive, preferably a slippery agent, is between 0.2 and 5% by weight, preferably 2% by weight relative to the total weight of the composition of the 'article. Multilayer article according to any one of claims 1 to 12, characterized in that layer C, when present, comprises barrier materials chosen from PVOH (poly vinyl alcohol), EVOH (Poly (vinyl alcohol-co-ethylene )), PVCD (polyvinyl chloride), PGA (polyglycolic acid), cellulose or polysaccharides and their mixtures in all proportions. Multilayer article according to any one of claims 1 to 13, characterized in that it is coextruded. Multilayer article according to one of claims 14, characterized in that it has a thickness greater than or equal to approximately 25 pm, approximately 50 pm, approximately 450 pm, approximately 750 pm and less than or equal to 5000 pm. Multilayer article according to one of claims 1 to 14, characterized in that the thickness of layer A or layer B is between 10 and 725 pm, between 18 and 30 pm, preferably equal to approximately 25 pm. Sheet, characterized in that it comprises a multilayer article according to claims 1 to 16. Sheet, in particular a tray, according to claim 17, characterized in that it has a thickness less than 5000 pm, preferably between 400 and 800 pm, more preferably equal to approximately 450 pm, even more preferably equal to approximately 750 pm. Film, characterized in that it comprises a multilayer article according to any one of claims 1 to 16. Film according to claim 19, characterized in that it has a thickness ranging from 20 to 100 μm, preferably from 25 to 80 μm. more preferably from 30 to 60 pm, even more preferably from around 50 pm. Use of a multilayer article according to any one of claims 1 to 14, for the preparation of a packaging, a lid, a cup, a plate, a beverage capsule, a tray or a blister of packaging.