Composition of (co)polyesters, single-layer film and use for packaging bag

Abstract

Composition comprising from 68% to 75% by weight of at least one rigid (co)polyester selected from the group consisting of polybutylene succinate, polylactide, polyhydroxyalkanoate; from 25 to 35% by weight of at least one flexible (co)polyester selected from the group consisting of polybutyrate, poly(ε-caprolactone) and PBS copolymers; from 0.2 to 5% by weight of at least one hydrophobic additive selected from the group consisting of behenamide, erucamide, stearamide and oleamide; process for preparing a monolayer film from this composition by extrusion blowing; monolayer film obtained and bakery product packaging articles comprising the monolayer film. Figure to be published with the abstract: none

Description

Title of the invention: Composition of (co)polyesters, single-layer film and use for packaging bag

[0001] The present invention relates to the field of flexible packaging suitable for food contact. It relates more particularly to biodegradable and advantageously compostable polymer compositions, usable for the manufacture of single-layer flexible films having a particularly low permeability to water vapor and usable for food packaging. Prior art

[0002] Global plastic production continues to increase and reached 390 million tonnes in 2021, consuming nearly 10% of global oil production. In Europe, more than 57 million tonnes were produced in 2021 (PlasticsEurope, 2022, including https: / / plasticseurope.org / wp-content / uploads / 2023 / 03 / PE-PLASTICS-THE-FACTS_F INAL_DIGITAL-1 .pdf).

[0003] Low and high density polyethylenes, respectively LDPE / LLDPE and HDPE, as well as polypropylene are the most used plastic materials, they represent respectively 14.7%, 9.3% and 16.6% of all plastic materials.

[0004] The packaging sector is the largest consumer of these plastic materials, accounting for more than 40% of demand in 2021. Their great success is due to their extreme versatility. In the field of food packaging, they are essential for protecting foodstuffs and ensuring their preservation and their nutritional and taste qualities until they are consumed. However, due to their long lifespan, their impact on the environment is considerable.

[0005] Collection and processing channels for these plastic materials have been set up to limit environmental pollution, but these channels remain partial. Indeed, plastic waste escapes collection and ends up in the environment. For example, the quantity of plastic waste in the oceans was estimated at 150 million metric tons in 2015 and is expected to reach 600 million metric tons by 2040 if nothing changes (National Géographie, 2020, in particular https: / / www.nationalgeographic.fr / environnement / 2020 / 08 / la-quantite-de-plastique-da ns-les-oceans-devrait-tripler-dici-2040).

[0006] Regarding the processing channels, they evolve from year to year. In 2020, 29.5 million tonnes of post-consumer plastic waste were collected in Europe. More than a third (35%) was recycled, 42% was incinerated and 23% was buried (PlaticsEurope, 2022).

[0007] More specifically, the recycling of plastic packaging in France amounted to around 30% in 2021 (CITEO, in particular https: / / www.citeo.com / le-mag / les-chiffres-du-recyclage-en-france). This figure is relatively low, and the fate of the different containers is very contrasting: 59% for bottles and flasks and only 11% for other plastic packaging. Indeed, recycling channels are evolving but not all plastics are currently recycled. Only PET and HDPE have established recycling channels.

[0008] For flexible plastic packaging, recycling is more complicated. In 2018, 310,000 tonnes were put on the chewed, 13% in polypropylene (PP), 39% in polyethylene (PE) and 48% in other plastics (complexes, etc.) (CITEO, in particular https: / / bo.citeo.com / sites / default / files / 2020-ll / 20201124_brochure_R%26D_Citeo_pa p_finale.pdf). Only flexible PE packaging can currently be recycled or rather transformed into granules that can be used to manufacture other plastic products such as pipes or bags for storing waste.

[0009] In this context, it appears essential to find alternatives to these conventional plastic materials.

[0010] For several years, innovations have been emerging, particularly in the field of bio-sourced and biodegradable plastics. These materials are already used for the manufacture of various products, including plastic bags. Examples of these polymers are polylactic acid (PLA), polybutylene succinate (PBS) and its derivatives, and polyhydroxyalkanoates (PHA).

[0011] These alternative materials available on the market have specific properties with advantages and disadvantages for each application: too flexible or too rigid, poor thermal stability, insufficient barrier properties, etc. This is the main reason why they are little used in food packaging.

[0012] However, there remains a need to have available flexible packaging that can be used in the food sector and which has sufficient barrier properties, in particular low permeability to water vapor. In the context presented above, there also remains a need to have available such packaging that is at least partially biosourced, and also biodegradable, preferably compostable.

[0013] There are already patent applications that describe sheets made of biodegradable, multi-layer polymers, i.e. formed from several layers composed of different polymer(s). The combination of these different layers of polymers makes it possible to benefit from the advantages of each of them. As an example, we can cite application WO2020 / 222232 which relates to a multi-layer sheet formed from a first and a second external layer of polymers comprising PBS or PBSA and of an inner layer comprising 70 to 80% by weight of PLA and 20 to 30% by weight of PCL, this type of sheets has good physical resistance and also to high temperatures. These sheets are mainly used to manufacture containers for containing liquids.

[0014] A solution to improve the barrier properties, proposed in particular in EP 2 790 920, was to add elements such as nano-clays to the polymer composition, however the use of nanoparticles is currently controversial, particularly in the food sector. In addition, it is very difficult to recycle articles incorporating nanoparticles as fillers; generally, the potential migration of these nanoparticles raises questions.

[0015] There still remains a need to have available polymer compositions allowing the production of films for packaging having low permeability to water vapor and easy to implement using conventional plastics processing tools.

[0016] The inventors thus directed their research towards polymer compositions allowing the production of single-layer films.

[0017] Single-layer sheets based on blends of (co)polyesters, impermeable to gases, are also described in particular in EP 2 998 342 A2, these sheets mainly comprise rigid polymers: they are typically formed from 80% by weight of PB S and 20% by weight of PLA. These sheets do not have the mechanical properties sought for the single-layer films according to the invention, in particular in terms of folding capacity or rigidity since the sheet of composition 80% by weight of PBS and 20% by weight of PLA has a Young's modulus equal to 569 MPa. Summary of the invention

[0018] Surprisingly and advantageously, the inventors have developed a particular (co)polyester composition having suitable mechanical properties for the formation of single-layer films usable for food packaging, these films having in particular improved barrier properties, notably in terms of permeability to water vapor.

[0019] A first object of the present invention relates to a composition comprising: -from 68% to 75%, preferably from 69% to 75% by weight of at least one rigid (co)polyester chosen from the group formed by polybutylene succinate (PBS), polylactide (PLA), polyhydroxyalkanoate (PHA), relative to the total weight of the composition; -from 25 to 35% by weight of at least one flexible (co)polyester chosen from the group formed by polybutylene adipate terephthalate or polybutyrate (PBAT), poly(£-caprolactone) (PCL) and copolymers of polybutylene succinate (PBS), relative to to the total weight of the composition; -from 0.2 to 5%, and preferably from 0.5 to 2% by weight of at least one hydrophobic additive chosen from the group formed by behenamide, erucamide, stearamide and oleamide, relative to the total weight of the composition.

[0020] A first advantage of these compositions is their ecological impact. The compositions according to the invention prepared from biodegradable polymers make it possible to obtain biodegradable and preferably compostable and / or recyclable articles having a significantly lower impact on the environment than articles prepared from plastics derived from petrochemicals and which are not biodegradable.

[0021] Indeed, the compositions according to the invention can be made from (co)polyesters derived from renewable resources, in this case, the composition is said to be “bio-sourced”.

[0022] The term "biosourced" or "biosourcing" refers to plastics made from plant-based resources such as corn, cassava, potato, wood, cotton, algae, sugar cane, beetroot, the biosourced nature is defined by the ASTM D6866-22 standard.

[0023] Advantageously, the compositions according to the present invention are prepared from (co)polyesters of which at least 50% by weight are of biosourced origin as defined in standard ASTM D6866-22.

[0024] The compositions according to the present invention are distinguished by their homogeneity, advantageously allowing the preparation of stable and homogeneous monolayer films suitable for use in the manufacture of flexible packaging for food. These films have in particular improved barrier properties, notably in terms of permeability to water vapor; they also have a very satisfactory permeability to oxygen for the intended uses.

[0025] These biodegradable (co)polyester compositions have both a good ability to be implemented by extrusion inflation on an industrial scale while retaining satisfactory physical and mechanical properties.

[0026] In particular, the compositions according to the present invention have good sealability properties allowing the single-layer film to be shaped industrially in the form of sachets.

[0027] Thus, a second object of the present invention relates to a process for preparing the monolayer film from the composition according to the invention comprising an extrusion-inflation step.

[0028] A third object of the invention relates to a single-layer film comprising, preferably consisting of, the composition according to the invention, or prepared according to the preparation method according to the invention, preferably, the single-layer film has a thickness ranging from 35.106 m to 40.106 m.

[0029] A fourth object of the invention relates to an article comprising, preferably consisting of, the single-layer film according to the present invention. Advantageously, the article according to the present invention is a wicket bag, called a “wicket bag”, preferably intended for the packaging of bakery products, in particular sandwich bread.

[0030] The article is advantageously biodegradable and compostable.

[0031] The term "biodegradable" or "biodegradability" means the property of a material to degrade under biological activity, for example under 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, of the other elements present (mineralization) and the appearance of a new biomass, under 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 the European Standard EN 13432:2000, as well as its French extension: NF 14995.

[0032] The term "recyclable" means the recovery of part or all of the constituents of a material that has reached the end of its life or of a material from manufacturing residues in order to reintroduce them into the production cycle of the same material or another material.

[0033] The term "compostable" or "compostability" means a process which consists of placing fermentable products in conditions (temperature, humidity, oxygenation, presence of soil microorganisms, etc.) allowing their biodegradation. To be considered compostable within the meaning of standard EN 13432: 2000, the material must be at least 90% biodegraded after 6 months in an industrial compost medium; at least 90% of the residues must be less than 2mm in size after 3 months of composting; and the absence of ecotoxic effects must be demonstrated as well as the agricultural quality of the compost obtained.

[0034] Advantageously, the articles according to the present invention are compostable after use under industrial composting conditions in accordance with standard EN 13432: 2000 and under domestic composting conditions in accordance with standard NF T 51-800:2015.

[0035] Other aspects, advantages and properties of the present invention are presented in the description and examples which follow.

[0036] Description of the invention

[0037] Composition

[0038] The composition according to the present invention comprises a mixture of at least two, preferably three biodegradable (co)polyesters.

[0039] The composition according to the present invention comprises from 68% to 75%, preferably from 69% to 75% by weight of at least one rigid (co)polyester chosen from the group formed by PBS, PLA, PHA relative to the total weight of said composition.

[0040] Preferably, the composition according to the present invention comprises, as rigid (co)polyesters, PLA and at least one other rigid polyester chosen from PBS and PHA.

[0041] More preferably, it comprises, as rigid (co)polyesters, from 63% to 72% by weight of at least one polyester chosen from the group formed by PBS and PHA relative to the total weight of the composition and from 3% to 7%, preferably from 4% to 6% by weight of PLA relative to the total weight of the composition.

[0042] For the purposes of the present invention, the term “rigid (co)polyester” means a polymer having the following characteristics: a rigidity modulus greater than 450 MPa, preferably greater than 500 MPa and less than 3600 MPa and an elongation at break greater than 2% and less than 400%, preferably less than 350%.

[0043] The composition according to the present invention also comprises from 25% to 35% by weight of at least one flexible (co)polyester chosen from the group formed by PB AT, PCL and PBS copolymers, preferably poly(butylene succinate adipate) (PBSA), relative to the total weight of said composition. Preferably, the composition comprises from 25% to 30% by weight of PBSA, relative to the total weight of said composition.

[0044] By "flexible (co)polyester", or flexible within the meaning of the present invention, is meant a polymer having the following characteristics: a rigidity modulus greater than 40 MPa and less than 500 MPa, preferably less than 350 MPa and an elongation at break greater than 300%, preferably greater than 400% and less than 700%.

[0045] The composition also comprises from 0.2 to 5%, and preferably from 0.5 to 2% by weight of at least one hydrophobic additive chosen from the group formed by behenamide, erucamide, stearamide and oleamide, relative to the total weight of the composition. Preferably, the hydrophobic additive is behenamide.

[0046] The composition also comprises, by weight relative to the total weight of the composition, from 0 to 5%, and preferably from 0.5 to 2% by weight of at least one vinyl polymer chosen from the group formed from grafted or ungrafted polyvinyl acetate and ungrafted ethylene polyvinyl acetate (ethylene-vinyl acetate copolymers), called PVAc, or grafted ethylene polyvinyl acetate. Preferably the vinyl polymer is polyvinyl acetate (PVAc).

[0047] By "grafted vinyl polymer" is meant that the vinyl polymer is modified by grafting, preferably with at least one agent chosen from the group consisting of maleic anhydride, glycidyl methacrylate, hydroxyethyl acrylate, methyl methacrylate, butyl acrylate, acrylic acid, preferably maleic anhydride and glycidyl methacrylate.

[0048] The composition also comprises from 0 to 10%, preferably from 0 to 5% of at at least one additive chosen from plasticizers, slip agents, processing aids, anti-blocking agents.

[0049] Thus, the compositions according to the present invention advantageously have a Young's modulus ranging from 200 to 420 MPa, preferably from 200 to 300 MPa.

[0050] The compositions according to the present invention advantageously have a threshold stress ranging from 12 MPa to 30 MPa.

[0051] The compositions according to the present invention advantageously have an elongation at the threshold ranging from 14% to 50%.

[0052] The compositions according to the present invention advantageously have an elongation at break ranging from 400% to 700%.

[0053] Young's modulus, also called modulus of rigidity or modulus of elasticity, is determined in accordance with standard NF EN ISO 527-1 of 2012-04-01.

[0054] The threshold stress, the threshold elongation and the elongation at break are also determined in accordance with standard NF EN ISO 527-1 of 2012-04-01.

[0055] The composition according to the invention is suitable for use in the formation of a single-layer film.

[0056] By "monolayer film" is meant a film formed from a single layer of (co)polyesters, homogeneous. Advantageously, the monolayer film has a thickness ranging from 35.106 μm to 40.106 μm (35 to 40 microns)

[0057] The inventors have thus shown that the compositions according to the invention have mechanical properties allowing the formation of a single-layer film sufficiently flexible and resistant to be used for the manufacture of packaging bags known as "wicket" also called bags on a spindle.

[0058] Furthermore, the composition according to the invention has good suitability for implementation (processability) on an industrial scale while retaining satisfactory physical and mechanical properties. The composition is suitable for use with automated packaging machines for the formation of flexible bags for packaging.

[0059] In addition, the films according to the present invention have a particularly low water vapor permeability. The water vapor permeability of the films according to the present invention ranges from 70 to 180 in g / (m2.day), preferably less than 160 in g / (m2.day) and more preferably less than 110 in g / (m2.day) determined in accordance with the ASTM E96-22 standard, on films with a thickness of 35.106 m.

[0060] Water vapor permeability is determined in accordance with ASTM E96-22, the methodology and measurement conditions related to this standard are detailed in Example 2 below.

[0061] Oxygen permeability (PO2) is determined in accordance with ASTM standards F1927: 2020 on films with a thickness of 35.106 m.

[0062] The compositions according to the invention may also comprise additives capable of improving the aesthetics, in particular the shine and / or the slip, or even reducing the opacity of the single-layer films.

[0063] The monolayer films according to the present invention are stable for several months: their physical properties are not degraded.

[0064] The articles according to the present invention are perfectly suitable for automatic packaging for the packaging of bread, bakery and pastry products, in particular sandwich bread, Viennese pastries, brioche bread, pain au chocolat, croissants and brioches.

[0065] Process for preparing a monolayer film

[0066] The single-layer film according to the present invention can be obtained by a process chosen from the “cast” extrusion processes also called flat die, bubble extrusion also called inflation extrusion, or tubular extrusion.

[0067] Preferably, the single-layer film according to the invention is obtained by an extrusion-inflation process.

[0068] Inflating extrusion is a plastics process that consists of shaping plastic films or sheaths. A thin sheath is extruded vertically through an annular die. This sheath, momentarily pinched, is inflated by a flow of air which is introduced through the axis of the die head. Under the action of stretching and inflation, a bubble is formed. Air cooling allows the sheath to solidify, which is then flattened by two panels converging towards drawing rollers. The rotation speed of these rollers allows the thickness of the sheath to be adjusted. The diameter of the sheath is, in turn, regulated by the volume of air in the sheath.

[0069] This process, followed by shaping including cutting and then sealing steps, allows the automated, simple, practical and economical production of an article in the form of a bag, in particular a plastic bag on a spindle or wicket bag.

[0070] Furthermore, the composition according to the present invention makes it possible to obtain printable plastic bags on spindles or wicket bags. The film printing step generally takes place before cutting and shaping. Of course, it is within the skill of the person skilled in the art to select the ink with the best printing properties depending on the desired visual result.

[0071] While ensuring optimal preservation and keeping the softness of pastries intact, this wicket bag provides great flexibility and can be available in several styles, with or without closures, in various shapes, materials and colors.

[0072] The following examples are intended to illustrate the invention without limiting its scope.

[0073] Examples

[0074] Example 1 - Compositions

[0075] Table 1 shows the compositions in accordance with the invention. The proportions of the different components are expressed as a percentage by weight relative to the weight of the final composition.

[0076] The PBS used is marketed under the name FZ91 by the company PTT MCC Biochem Company Ltd.

[0077] The PBSA used is marketed under the name FD92 by the company PTT MCC Biochem Company Ltd.

[0078] The PLA used is marketed under the name LX975 by the company To-talEnergy Corbion.

[0079] The PVAc used is a product in the form of microbeads marketed under the name Vinnex by the company WACKER.

[0080] [Table 1] Compositions in accordance with the invention Fl F2 F3 F4 F5 % PBS (rigid) 69.3 64.5 64.3 64.0 63.7 % PBSA (flexible) 29.7 28.3 28.2 28.1 27.9 % PLA (rigid) 0.0 4.9 4.9 4.8 4.8 % Hydrophobic Additive (1) 1.0 1.0 1.0 1.0 1.0 PVAc 0.0 1.0 1.0 1.0 1.0 Slip agent (2) 0.0 0.2 0.4 0.7 1.0 Anti-blocking agent: talc 0.0 0.1 0.2 0.4 0.6 Sum of rigid polyesters 69.3 69.4 69.2 68.8 68.5

[0081] (1) Crodamide BR marketed by the company CRODA

[0082] (2) Incroslip SL marketed by the company CRODA.

[0083] Table 2 presents the comparative compositions. The proportions of the different components are expressed as a percentage by weight relative to the weight of the final composition.

[0084] [Table 2] - Comparative compositions Cl C2 PBS (rigid) 70 62.0 PBSA (flexible) 30 27.2 PLA (rigid) 0.0 4.7 Hydrophobic additive (1) 0.0 0.9 PVAc 0.0 0.9 Slip agent (2) 0.0 2.8 Anti-blocking agent: talc 0.0 1.5 Rigid polyester sum 70 66.7

[0085] Process for preparing the compositions

[0086] The different components of the compositions are mixed (compounded) by an extrusion process, that is to say that the (co)polyesters and additives are mixed using an extruder. The extruder used is a ZSE 27 MAXX / HP twin-screw extruder. It is composed of an endless twin-screw which rotates inside the cylindrical barrel regulated in temperature by heating and cooling systems. The twin-screw has a profile allowing to obtain a homogeneous mixture and a good dispersion of the different components of the formulation at the outlet of the die. The polymers and the additives are introduced into the feed hoppers before being sent, in a precise order and zone in the extruder.The extruder allows the biodegradable (co)polyesters and the additives of said composition to be conveyed, melted, pressurized and mixed in order to obtain a rod at the outlet of the die which will then be cooled in a water bath before being granulated and then implemented by extrusion inflation.

[0087] The adjustment of the temperatures of the different zones of the extruder was carried out in accordance with the phase change temperatures of the biodegradable (co)polyesters and their degradation temperature. The screw speed inside the barrel was chosen so as to ensure good mixing of said composition by shearing without degrading the material. The parameters used are gathered in the table below.

[0088] The biodegradable (co)polyesters are pre-dosed and introduced into the main hopper. The additives are pre-dosed and incorporated into a secondary hopper.

[0089] Table 3 shows the parameters of the twin-screw extruder for the production of the composition in the form of granules.

[0090] Table 3: Parameters of the twin-screw extruder Zone 1 2 3 4 5 6 Temperature (°C) 140 140 145 145 150 150 Zone 7 8 9 10 11 12 Temperature (°C) 155 160 160 165 165 170

[0091] Speed: 45-60 kg / h.

[0092] Extrusion inflation

[0093] The inflation extrusion was carried out with a CMG model 4530 / HTM single-screw extruder with air cooling, having a centrally fed die with radiating channels and a die diameter of 0.1 m (100 mm).

[0094] Table 4 shows the parameters of the extrusion extruder (inflating) for the production of the single-layer film

[0095] Table 4: Bubble extruder parameters (inflation extrusion) Zone 1 2 3 4 5 6 7 Temperature (°C) 135 140 150 155 160 165 165 Screw speed (rpm) 20-40 Draft speed (m / min) 7-11 % outside air 30-40

[0096] Example 2 - Properties of monofilms

[0097] Physical properties

[0098] The Young's modulus, yield stress, yield strain and elongation at break values ​​of the compositions were measured in accordance with the protocols of EN ISO 527-1 (2012-04-01).

[0099] It has thus been verified that the compositions according to the invention have:

[0100] a Young's modulus ranging from 200 to 420 MPa, preferably from 200 to 300 MPa;

[0101] a threshold stress ranging from 12 MPa to 30 MPa;

[0102] an elongation at the threshold ranging from 14% to 50%;

[0103] a higher elongation at break ranging from 400% to 700%.

[0104] Water vapor permeability

[0105] L Sample preparation

[0106] The samples of the monolayer films to be tested were placed at 23°C throughout their storage before analysis. The monolayer films had a thickness of 35.106 μm.

[0107] 2, Conditions for carrying out the tests

[0108] The tests were carried out under the following conditions:

[0109] - Location of the cut: the samples were taken in different places on the coil, on the external face of the coil:

[0110] - Surface area of ​​the test pieces: 50 cm2

[0111] - the analysis of the thickness of the specimens subjected to the tests was carried out in 5 points of the test pieces.

[0112] 3. Methodology

[0113] The analysis is carried out according to a method based on the ASTM E96-22 standard using the desiccant method (gravimetric method). According to this standard, capsules containing a desiccant (anhydrous silica gel) and sealed with the material, i.e. the single-layer film under test, are placed in a controlled atmosphere. These capsules are weighed at regular time intervals. The increase in mass makes it possible, as soon as it is proportional to the time interval, to determine the water vapor transmission coefficient.

[0114] Water vapor transmission rates are expressed in g / (m2.day).

[0115] 4, Measurement conditions

[0116] The measurements were carried out under the following conditions: in a climatic chamber, with a 10 4g precision balance, using permeability cups.

[0117] The set temperature and humidity values: 38°C and 90%RH.

[0118] The tests were carried out in triplicate, i.e. the number of samples submitted in the tests was 3 per reference.

[0119] Water vapor permeability was measured on monolayer films of 35.10 6m.

[0120] Table 4 lists the water vapor permeability values ​​of the 35.106m monolayer films obtained from the compliant and comparative compositions presented above.

[0121] [Tables4] Composition of films PHjO g / (m2.day) Fl 93 + 4 F2 108 + 7 F3 152 + 9 F4 163+10 F5 171 + 5 Cl 416 + 16 C2 225 + 23 The monolayer films according to the invention Fl-F5 have a permeability to significantly lower water vapor than the comparative monolayer films Cl and C2.

[0122] Oxygen permeability

[0123] 1, Preparation of samples

[0124] The samples of the monolayer films to be tested were placed at 23°C throughout their storage before analysis. The monolayer films had a thickness of 35.106 μm.

[0125] 2, Conditions for carrying out the tests

[0126] The tests were carried out under the following conditions:

[0127] - Location of the cut: the samples were taken in different places on the coil, on the external face of the coil:

[0128] - Surface area of ​​the test pieces: 50 cm2

[0129] - the analysis of the thickness of the specimens subjected to the tests was carried out in 5 points of the test pieces.

[0130] 3. Methodology

[0131] The analysis is carried out according to a method based on the ASTM F1927: 2020 standard.

[0132] According to this standard, samples are cut and placed in the cells of the permeability measuring device. The inner face of the material is swept with the carrier gas continuously while the outer face is swept with the test gas. The oxygen diffuses through the material and is directed towards the detector.

[0133] The oxygen transfer coefficient is expressed in cm3 / (m2.day.latm).

[0134] 4, Measurement conditions

[0135] The measurements were carried out under the following conditions: - Device: OXTRAN 2 / 22 H with coulometric detector; - Carrier gas: N2 / 5%H2 mixture; Test gas: pure oxygen;

[0136] - The set temperature and humidity values: 23°C and relative humidity at inside 50% - Relative humidity outside 50% The tests were carried out twice, i.e. the number of samples subjected to the tests was 2 per reference.

[0137] Water vapor permeability was measured on monolayer films of 35.10 6m.

[0138] The compositions according to the present invention have an oxygen permeability coefficient ranging from 410 to 520 cm3 / (m2.day.atm). This range of values ​​is very satisfactory for the intended application since it is significantly lower than the value obtained with conventional plastic films such as polyethylenes or polypropylenes.

[0139] The compositions according to the present invention make it possible to obtain single-layer films having adequate strength and flexibility for the intended uses.

[0140] These packages have a pleasant feel (“soft touch” in English).

[0141] These films are strong enough for use in packaging bakery products, they are not easily torn.

[0142] The films obtained are suitable for food contact as defined by Regulation (EU) No. 10 / 2011 (REGULATION (EU) No. 10 / 2011 of the Commission of 14 January 2011). It has been observed that sliced ​​bread stored in a wicket bag made from a composition according to the invention retains its nutritional and organoleptic properties for at least 17 days.

[0143] The films obtained have a water vapor permeability of less than 180 in g / (m2.day), preferably less than 160 in g / (m2.day) determined in accordance with the ASTM E96-22 standard, on films with a thickness of 35.106 m.

Claims

Claims

1. Composition comprising: -from 68% to 75%, preferably from 69% to 75% by weight of at least one rigid (co)polyester chosen from the group formed by polybutylene succinate, polylactide, polyhydroxyalkanoate, relative to the total weight of the composition; -from 25% to 35% by weight of at least one flexible (co)polyester chosen from the group formed by polybutylene adipate terephthalate, poly(β-caprolactone) and copolymers of polybutylene succinate, relative to the total weight of the composition; -from 0.2 to 5% and preferably from 0.5 to 2% by weight of at least one hydrophobic additive chosen from the group formed by behenamide, erucamide, stearamide and oleamide, relative to the total weight of the composition.

2. Composition according to claim 1 comprising, as rigid (co)polyesters: - from 63% to 72% by weight of at least one polyester chosen from the group formed by polybutylene succinate and polyhydroxyalkanoate relative to the total weight of the composition and - from 3% to 7%, preferably from 4% to 6% by weight of polylactide relative to the total weight of the composition.

3. Composition according to any one of the preceding claims comprising, as flexible polymer: -from 25% to 30% by weight of poly(butylene succinate adipate) relative to the total weight of said composition.

4. Composition according to any one of the preceding claims comprising from 0 to 5%, and preferably from 0.5 to 2% by weight of at least one vinyl polymer chosen from the group formed from grafted or ungrafted polyvinyl acetate and ungrafted polyethylene vinyl acetate or grafted polyethylene vinyl acetate, preferably the vinyl polymer is polyvinyl acetate.

5. Composition according to any one of the preceding claims comprising from 0 to 10%, preferably from 0 to 5% of at least one additive chosen from plasticizers, slip agents, processing aids, anti-blocking agents.

6. A composition according to any preceding claim comprising: -from 60 to 65% by weight of PBS, and from 3 to 7% of PLA, as rigid polymers, relative to the total weight of the composition; -from 25 to 30% by weight of PBSA as flexible polymer, relative to the total weight of the composition; -from 0.5 to 2% by weight of behenamide relative to the total weight of the composition; -from 0.2 to 5%, and preferably from 0.5 to 2% by weight of polyvinyl acetate relative to the total weight.

7. Composition according to any one of the preceding claims prepared from (co)polyesters of which at least 50% by weight are of bio-sourced origin as defined by standard ASTM D6866-22.

8. Process for preparing a single-layer film from the composition according to any one of claims 1 to 7 comprising an extrusion-blowing step.

9. Single-layer film comprising, preferably consisting of, the composition according to any one of claims 1 to 7, or prepared according to the process according to claim 8, preferably with a thickness ranging from 35.106 m to 40.106 m.

10. Single-layer film according to the preceding claim having the following properties: a water vapor permeability ranging from 70 to 180 in g / (m2.day), preferably less than 160 in g / (m2.day), and more preferably less than 110 in g / (m2.day), the water vapor permeability being determined in accordance with standard ASTM E96-22, on films with a thickness of 35.106 m.

11. An article comprising, preferably consisting of, the monolayer film of any one of claims 9 or 10.

12. Article according to claim 11 characterized in that it is a bag on a skewer, called a "wicket bag", preferably intended for the packaging of bakery products, in particular sandwich bread.