Compositions based on polyamides and polymers comprising polyamide blocks and polyethylene glycol blocks

Abstract

The present invention relates to a composition comprising a polyamide, a polymer having a polyamide (PA) block and a polyethylene glycol (PEG) block, a functionalized polyolefin and a polyolefin wherein the weight ratio of (a + b) / (c + d) is lt; 1. The invention also relates to a method for preparing said composition, a kit for obtaining said composition, an article comprising or made from said composition, and a method for preparing said article.

Description

Technical Field

[0001] The present invention relates to a composition comprising polyamide, a polymer having a polyamide (PA) block and a polyethylene glycol (PEG) block, a functionalized polyolefin and a polyolefin. The present invention also relates to a method for preparing the composition, a kit for obtaining the composition, an article comprising or made of the composition and a method for preparing the article. Background Art

[0002] Nonporous breathable films or impermeable but breathable films are widely used in various applications. As one such application, nonporous breathable films are advantageously used for packaging, particularly food packaging, for example packaging of fresh products such as fruits, vegetables, freshly cut meat and fish. The quality and shelf life of these fresh products can be enhanced by optimizing the environment within the packaging in which they are enclosed, particularly by adjusting the moisture vapor transmission rate (MVTR), the amount of gases such as CO 2 and O 2 MVTR, also known as water vapor transmission rate (WVTR), is the amount of water vapor that passes through a substance or material in a specific period of time. For food packaging and storage, too high MVTR values ​​are undesirable because this may cause fruits or vegetables to wilt.

[0003] Document US 5959042 discloses a material for obtaining a nonporous breathable membrane, which comprises (a) a polyamide, (b) a polymer having a PA block and a polyether PEG block, (c) an optional polyolefin, and (d) a functionalized polyolefin, wherein the amounts by weight of a, b, c and d are such that a>0, b>0, c+d>0, a+b+c+d=100, a / b>0.2, (a+b) / (c+d)>1, and b / (a+b+c+d)<0.5.

[0004] Document EP 0476963 discloses a polymer blend for preparing a non-porous breathable membrane, which comprises a hydrophilic block poly(ether-co-amide) containing about 20 to about 80 weight percent PEG blocks and a hydrophobic polymer selected from any of the following: a) a block poly(ether-co-amide) substantially free of PEG blocks, b) a polyamide, c) a polyester, or d) a polyurethane.

[0005] However, there remains a need to optimize the MVTR, gas permeability, and / or processability of films. More generally, there is a need for a composition to prepare improved packaging materials, such as films or sheets, to preserve food or fresh produce in an ideal environment. Summary of the invention

[0006] The present invention relates to a composition comprising:

[0007] (a) polyamide (PA),

[0008] (b) a polymer having a polyamide (PA) block and a polyethylene glycol (PEG) block,

[0009] (c) a functionalized polyolefin, and

[0010] (d) polyolefins,

[0011] The weight ratio of (a+b) / (c+d) is <1.

[0012] In some embodiments, the weight ratio of b / (a+b+c+d) is equal to or less than 0.5, typically 0.05 to 0.5, preferably 0.1 to 0.5, such as 0.05 to 0.4.

[0013] The present invention makes it possible to solve the above needs. More specifically, it provides suitable MVTR and gas permeability, which contribute to an ideal environment in food packaging, thus contributing to better quality and longer shelf life of the packaged food.

[0014] This is achieved by a combination of polyamides, polymers with PA and PEG blocks, functionalized polyolefins and polyolefins. It is noteworthy that by choosing a weight ratio of the amount of polyamide (a) and polymer (b) to the amount of functionalized polyolefin (c) and polyolefin (d) <1, the composition according to the invention advantageously enables the provision of films with improved qualities in terms of MVTR, gas permeability and processability. Therefore, the composition according to the invention is particularly useful for the preparation of films, sheets or bags for food packaging. Such packaging based on the composition according to the invention can reduce wilting and prevent mold growth of fresh products (such as fruits and vegetables) encapsulated therein during storage and / or transportation. DETAILED DESCRIPTION

[0015] The invention will now be described in more non-limiting detail in the following description.

[0016] The composition according to the present invention comprises (a) polyamide (PA), (b) a polymer having polyamide (PA) blocks and polyethylene glycol (PEG) blocks, (c) a functionalized polyolefin and (d) a polyolefin.

[0017] (a) Polyamide

[0018] In the present application, the term "polyamide" represents the condensation product of one or more monomers selected from amino acids or aminocarboxylic acids, lactams and monomers resulting from the reaction between aliphatic diamines and dicarboxylic acids, more specifically, the condensation product of,

[0019] - one or more amino acids such as aminocaproic acid, amino-7-heptanoic acid, amino-11-undecenoic acid and amino-12-dodecanoic acid; or one or more corresponding lactams, such as caprolactam, enantholactam and laurolactam; or

[0020] - an essentially stoichiometric combination of one or more aliphatic and / or cycloaliphatic and / or aromatic-aliphatic diamines or salts thereof with one or more aliphatic or aromatic carboxylic diacids or salts thereof; examples of such diamines are hexamethylenediamine, dodecamethylenediamine, meta-xylylenediamine, bis(4-aminocyclohexyl)-methane (BACM), bis(3-methyl-4-amino-cyclohexyl)-methane (BMACM) and trimethylhexamethylenediamine, examples of diacids are terephthalic acid, isophthalic acid, adipic acid, azelaic acid, sebacic acid, suberic acid and dodecanedicarboxylic acid; or

[0021] - any mixture of the above monomers; and

[0022] - Any mixtures of the condensation products obtained, optionally together with other polymers that are compatible with the polyamide.

[0023] For example, the polyamide (PA) can be selected from PA6, PA6.6, PA6.10, PA10.10, PA10.12, PA11, PA12, PA6.12 and PA12.12, preferably from PA10.10, PA10.12, PA11, PA12, PA6.12 and / or PA12.12, the first number indicating the number of carbon atoms of the diamine and the second number indicating the number of carbon atoms of the dicarboxylic acid; or a single number indicating the number of carbon atoms in the repeating unit obtained from an amino acid or a lactam.

[0024] Preferably, the average carbon content of the repeating units of the polyamide is at least 8, preferably 8 to 14, more preferably 10 to 12.

[0025] Typically, the polyamide (PA) is selected from PA10.10, PA10.12, PA11, PA12 and PA12.12.

[0026] According to one embodiment, the melting temperature of the polyamide (PA) of the present invention is less than 210°C, for example less than 205°C, or less than 200°C.

[0027] The molecular weight of the polyamide can vary widely, as will be appreciated by those skilled in the art.

[0028] The term "average carbon content of the repeating units" means the average value of the number of carbon atoms of each repeating unit present in the polyamide, weighted by the molar proportion of said repeating units relative to the total amount of the polyamide block. For example, when the polyamide comprises a single repeating unit, as in the case of PAX or PAXY as defined above, the average carbon content of the repeating units of the polyamide block is equal to the number of carbon atoms of said repeating unit, provided that the polyamide repeating unit contains only one amide functional group in a known manner. In the case of a PAX block, the number of carbon atoms of the repeating unit is X. In the case of a PAXY block, the number of carbon atoms of the repeating unit is (X+Y) / 2, since the unit XY contains two amide functional groups.

[0029] Mixtures of polyamides are also possible.

[0030] Preferably, the polyamide (PA) in (a) is or comprises PA11 or PA12, preferably PA11. PA11 advantageously has good miscibility with polyolefins, thereby providing good processability of the composition, which facilitates the manufacture of thinner films or sheets.

[0031] (b) Polymer PEBA

[0032] In the present application, polymers having polyamide blocks and polyether blocks may also be referred to as polyether block amides (PEBAs).

[0033] The polymer (b) having a polyamide (PA) block and a polyethylene glycol (PEG) block may also be referred to as PA / PEG.

[0034] In some embodiments, polymer (b) consists of polyamide blocks and polyethylene glycol blocks.

[0035] This polymer with PA blocks and PEG blocks is produced by the co-condensation of polyamide sequences with reactive ends and polyether sequences with reactive ends, such as:

[0036] - polyamide sequences with diamine ends and polyoxyalkylene sequences with dicarboxylic acid ends;

[0037] - polyamide sequences with dicarboxylic acid ends and polyoxyalkylene sequences with diamine ends, obtained by cyanoethylation and hydrogenation of aliphatic dihydroxy α-ω polyoxyalkylene sequences, known as polyether diols;

[0038] - polyamide sequences with diamine ends and polyetherdiol sequences, in this particular case the product obtained is a polyetheresteramide (hereinafter abbreviated to PEEA).

[0039] Such polymers are described, for example, in French Patent Serial Nos. 74 189 13 and 77 266 78 and in the following U.S. Patent Nos. 4,331,786, 4,115,475, 4,195,015, 4,839,441, 4,864,014, 4,230,838 and 4,332,920, the contents of which are incorporated herein by reference.

[0040] Polyamide sequences with dicarboxylic acid ends are obtained, for example, from the condensation of a substantially stoichiometric combination of aminocarboxylic α-ω acids, lactams or carboxylic diacids and diamines in the presence of chain-limiting carboxylic diacids. The polyamide blocks may be PA6, PA6.6, PA6.10, PA10.10, PA10.12, PA11, PA12, PA6.12 and PA12.12, preferably PA10.10, PA10.12, PA11, PA12, PA6.12, PA11.12 and / or PA12.12. Preferably, the polyamide blocks are PA11 or PA12, preferably PA11.

[0041] Preferably, the average carbon content of the repeating units of the polyamide blocks is at least 8, preferably 8 to 14, more preferably 10 to 12.

[0042] According to one embodiment, the polyamide of the polyamide blocks in (b) is the same as the polyamide in (a).

[0043] The number-average molar mass Mn of the polyamide sequences PA varies between 300 and 15,000, preferably between 600 and 5,000.

[0044] Regardless of whether the polyether blocks are contained in the polymer chain with polyamide blocks and polyether blocks in the form of diols or in the form of diamines, for simplicity they will be referred to as PEG blocks.The number average molar mass Mn of the polyether sequences is from 100 to 6,000, preferably from 300 to 3,000.

[0045] The number-average molar mass can be set via the content of chain limiters. It can be calculated according to the following equation:

[0046] Mn=n 单体 × Mw 重复单元 / n 链限制剂 +Mw 链限制剂

[0047] In this formula, n 单体 represents the number of moles of monomer, n 链限制剂 represents the number of moles of excess limiting agent (e.g. diacid), Mw 重复单元 represents the molar mass of the repeating unit, and Mw 链限制剂represents the molar mass of the excess limiting agent. The number average molar mass of the hard block and the soft block can be measured by gel permeation chromatography (GPC) before block copolymerization.

[0048] Polymers with PA blocks and PEG blocks may also contain randomly distributed parts. Such polymers can be prepared by reacting precursors of polyether and polyamide blocks simultaneously. For example, a reaction can be induced between a polyether diol, a lactam (or the corresponding α-ω amino acid) and a chain-limiting diacid in the presence of a small amount of water. The polymer obtained essentially has polyether blocks, polyamide blocks of widely varying lengths, and various reagents that have reacted randomly and are randomly distributed along the polymer chain.

[0049] The polymer having PA blocks and PEG blocks may have, for example, a Shore D hardness typically comprised between 20 and 75 and advantageously between 30 and 70, and an intrinsic viscosity comprised between 0.8 and 2.5, measured in m-cresol at 20° C. for an initial concentration of 0.5% m / m.

[0050] Polymers having PA blocks and PEG blocks can be formed from 5 to 85 wt% polyether PEG blocks (and 95 to 15 wt% PA), and preferably 20 to 80 wt% polyether PEG blocks (and 80 to 20 wt% PA), and more preferably 30 to 70 wt% polyether PEG blocks (and 70 to 30 wt% PA).

[0051] In some embodiments, polymer (b) comprises at least 30 wt%, preferably at least 40 wt%, more preferably at least 50 wt% polyethylene glycol (PEG), relative to the total weight of polymer (b).

[0052] Preferably, the polymer having a PA block and a PEG block comprises a single type of block. Advantageously, a polymer having a PA11 block and a PEG block (PA11 / PEG), or a polymer having a PA12 block and a PEG block (PA12 / PEG) is employed. PA11 advantageously has good miscibility with polyolefins, thus providing good processability of the composition, which helps to manufacture thinner films or sheets.

[0053] However, it is also possible to use blends of polymers having polyamide blocks and polyether blocks.

[0054] Such polymers having polyamide blocks and polyether blocks are commercially available under the trade names Pebax®, ® from ARKEMA or under the trade name VESTAMID® from EVONIK.

[0055] These polymers having PA blocks and PEG blocks are characterized by water vapor permeability and are designated as "hydrophilic" as conventionally understood by those skilled in the art.

[0056] (c) Functionalized polyolefins

[0057] In the present application, the term "functionalized polyolefin" means a polymer of an alpha-olefin and a reactive unit (functional group); such reactive unit is an acid, anhydride or epoxy functional group.

[0058] The functionalized polyolefin (c) is used as a compatibilizer or a compatibilizer for compatibilizing polyamide and polyolefin.

[0059] As examples, we can cite polyolefins previously grafted or copolymerized or terpolymerized with unsaturated epoxides such as glycidyl (meth)acrylate, or with carboxylic acids or corresponding salts or esters such as (meth)acrylic acid (the latter can be partially or completely neutralized with metals such as Zn, etc.), or further with carboxylic anhydrides such as maleic anhydride. The term "copolymerized or terpolymerized" means that the functional groups are then integrated into the polymer backbone.

[0060] Functionalized polyolefins (c) may be the following (co)polymers grafted with maleic anhydride or glycidyl methacrylate, wherein the grafting rate is, for example, 0.01 to 5% by weight:

[0061] PE, PP, copolymers of ethylene with propylene, butene, hexene or octene, containing, for example, 35 to 80% by weight of ethylene;

[0062] - copolymers of ethylene and vinyl acetate (EVA) containing up to 40% by weight of vinyl acetate;

[0063] - copolymers of ethylene and alkyl (meth)acrylate containing up to 40% by weight of alkyl (meth)acrylate;

[0064] - copolymers of ethylene and vinyl acetate (EVA) and alkyl (meth)acrylates containing up to 40% by weight of EVA and alkyl (meth)acrylates,

[0065] - Ethylene / propylene copolymers having a major part of the propylene grafted with maleic anhydride and then condensed with a monoaminated polyamide (or polyamide oligomer). These products are described in EP 0342066.

[0066] The functionalized polyolefin (c) may also be a copolymer or terpolymer of at least one of the following units: (1) ethylene, (2) an alkyl (meth)acrylate or a vinyl (meth)acrylic acid or a saturated carboxylic acid ester and (3) maleic anhydride or glycidyl (meth)acrylate.

[0067] As examples of functionalized polyolefins of the latter type, mention may be made of the following copolymers, in which ethylene preferably represents at least 60% by weight of the copolymer, and in which monomer (3) represents, for example, from 0.1 to 10% by weight of the copolymer:

[0068] - ethylene / alkyl (meth)acrylate or (meth)acrylic acid / maleic anhydride or glycidyl methacrylate copolymers;

[0069] - ethylene / vinyl acetate / maleic anhydride or glycidyl methacrylate copolymers;

[0070] - Ethylene / vinyl acetate / alkyl (meth)acrylate or (meth)acrylic acid / maleic anhydride or glycidyl methacrylate copolymers.

[0071] In the above copolymer, (meth)acrylic acid may be present in the form of a Zn or Li salt.

[0072] The term "alkyl (meth)acrylate" preferably represents C 1 To C 6 Alkyl esters and may be selected from methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate and 2-ethylhexyl acrylate, and most preferably methyl methacrylate and ethyl methacrylate.

[0073] Advantageously, the functionalized polyolefin (c) is or comprises an ethylene / butyl acrylate / maleic anhydride copolymer or an ethylene / ethyl acrylate / glycidyl methacrylate copolymer.

[0074] Furthermore, these polyolefins may also be crosslinked using any suitable method or agent (diepoxides, diacids, peroxides, etc.); the expression functionalized polyolefin also encompasses the above polyolefins crosslinked with difunctional agents such as diacids, dianhydrides, diepoxides, and the like.

[0075] The molecular weight, MFI index and density of these functionalized polyolefins can also vary widely, as will be appreciated by those skilled in the art.

[0076] Mixtures of functionalized polyolefins are also possible.

[0077] Preferably, the functionalized polyolefin (c) is or comprises a copolymer of ethylene and glycidyl methacrylate (GMA). For example, GMA gives 2The reactivity results in optimal dispersion during melt blending with engineering thermoplastics such as polyamides, polyesters, and polyphenylene sulfides. As an ethylene copolymer, ethylene-GMA copolymer is compatible with LDPE in essentially all proportions and is compatible with nearly all other ethylene copolymers. Ethylene-GMA copolymer advantageously has good miscibility with polyolefins, thus providing good processability, which is beneficial for manufacturing thinner films or sheets.

[0078] (d) Polyolefin

[0079] Polyolefin (d) is a homopolymer or copolymer of an α-olefin and / or a diene (such as ethylene, propylene, butene-1, octene-1, butadiene).

[0080] Polyolefin (d), which is different from the functionalized polyolefin (c), does not contain any reactive units (functional groups) such as acid, acid anhydride, or epoxy functional groups.

[0081] Examples are:

[0082] - Homopolymers such as polyethylene, especially LDPE (low-density polyethylene), HDPE (high-density polyethylene), LLDPE (linear low-density polyethylene), or VLDPE (very low-density polyethylene), metallocene polyethylene, or polypropylene;

[0083] - Ethylene / α-olefin copolymers, such as ethylene / propylene;

[0084] - Ethylene propylene rubber (EPR), styrene / ethylene-butene / butadiene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS), and ethylene / propylene / diene (EPDM) block copolymers;

[0085] - Copolymers of ethylene with a product selected from at least one of unsaturated carboxylates or esters (such as (meth)acrylic acid alkyl esters, usually methyl acrylate) or vinyl esters of saturated carboxylic acids (such as vinyl acetate), where the proportion of the comonomer can be up to 40% by weight.

[0086] The above copolymers can be copolymerized in a random or sequential manner and have a linear or branched structure.

[0087] According to ASTM D1238, at a standard load of 2.16 kg and a die temperature of 190 °C, the polyolefin can have, for example, a density included between 0.86 and 0.965 and a melt flow index MFI included between, for example, 0.3 and 40. The polyolefin can also be crosslinked using any suitable reagent (such as epoxy, etc.).

[0088] Polyolefin mixtures are also possible.

[0089] Preferably, the polyolefin in (d) is or comprises an ethylene-methyl acrylate copolymer or LLDPE.

[0090] Composition

[0091] The composition according to the invention comprises (a) a polyamide, (b) a polymer having polyamide (PA) blocks and polyethylene glycol (PEG) blocks, (c) a functionalized polyolefin, and (d) a polyolefin, as defined above.

[0092] In one embodiment, in the composition according to the invention, the weight ratio of (a) / (b) is less than 1, preferably from 0.05 to 0.95, more preferably from 0.1 to 0.5, even more preferably from 0.25 to 0.45.

[0093] Preferably, the weight ratio of b / (a + b + c + d) is from 0.1 to 0.5.

[0094] In some embodiments, (a) is present in an amount of 10 - 30% by weight relative to the total weight of (a)+(b)+(c), (b) is present in an amount of 40 - 80% by weight relative to the total weight of (a)+(b)+(c), and (c) is present in an amount of 10 - 30% by weight relative to the total weight of (a)+(b)+(c).

[0095] In one embodiment, relative to the total weight of the composition, i.e., relative to the total weight of (a)+(b)+(c)+(d), (d) is present in an amount of 40 - 70% by weight.

[0096] In some embodiments, (a) is present in an amount of 5 - 15% by weight relative to the total weight of the composition (i.e., the total weight of (a)+(b)+(c)+(d)), (b) is present in an amount of 15 - 40% by weight relative to the total weight of (a)+(b)+(c)+(d), (c) is present in an amount of 5 - 15% by weight relative to the total weight of (a)+(b)+(c)+(d), and (d) is present in an amount of 40 - 70% by weight relative to the total weight of (a)+(b)+(c)+(d).

[0097] Preferably, the composition according to the invention does not contain styrene maleic anhydride (SMA).

[0098] The composition according to the invention may also be mixed with additional additives, such as fillers, pigments and / or dyes.

[0099] Method for preparing the composition

[0100] The invention also relates to a method for preparing the composition according to the invention.

[0101] The method comprises the steps of blending:

[0102] (a) polyamide (PA),

[0103] (b) a polymer having a polyamide (PA) block and a polyethylene glycol (PEG) block,

[0104] (c) a functionalized polyolefin, and

[0105] (d) polyolefins,

[0106] The weight ratio of (a+b) / (c+d) is less than 1.

[0107] Each of (a) polyamide, (b) polymer having polyamide (PA) blocks and polyethylene glycol (PEG) blocks, (c) functionalized polyolefin, and (d) polyolefin is those defined above.

[0108] (a), (b), (c) and (d) may be blended together in one step. Alternatively, one or some of (a), (b), (c) and (d) may be blended separately in any order.

[0109] In some embodiments, the method includes the step (i) of blending (a) polyamide, (b) a polymer having a polyamide (PA) block and a polyethylene glycol (PEG) block, and (c) a functionalized polyolefin to obtain a base polymer blend or mixture, and the step (ii) of blending (d) polyolefin into the base polymer blend or mixture.

[0110] Preferably, the base polymer blend or mixture is in pellet form prior to step (ii).

[0111] The blending step may be a step of dry blending the components in powder form.

[0112] Alternatively and preferably, the blending step may be a step of melt blending some or all of the components. Melt blending may be performed in particular by admixture. For example, melt blending may be performed in an extruder or a co-kneader, more preferably a twin screw extruder or a co-kneader.

[0113] The melt blending may be performed at a temperature of 140 to 300°C, preferably 160 to 270°C, more preferably 180 to 210°C.

[0114] Preferably, the (d) polyolefin is dry blended into the base polymer blend or mixture.

[0115] At the end of the blending step, the composition can be produced, for example, in the form of flakes, crumbs, granules or pellets. Alternatively, it can be further milled or ground into a powder. It can also be provided in the form of a paste.

[0116] The step (i) of blending (a), (b) and (c) to obtain a base polymer blend or mixture and the step (ii) of blending (d) into the base mixture can be performed simultaneously or in a time-separated manner. Specifically, step (i) can be rewritten as a step of obtaining a base polymer blend or mixture by blending (a), (b) and (c), and step (ii) can be performed by blending (d) into the base polymer blend or mixture previously obtained by step (i) (e.g., a few hours, days or months before step (ii)).

[0117] Kit for obtaining the composition

[0118] The invention also relates to a kit for obtaining the composition according to the invention.

[0119] The kit comprises a first component and a second component, and the weight ratio of (a+b) / (c+d) is less than 1. The first component comprises (a) polyamide (PA), (b) a polymer having a polyamide (PA) block and a polyethylene glycol (PEG) block, and (c) a functionalized polyolefin. The second component comprises (d) polyolefin.

[0120] Each of (a) polyamide, (b) polymer having polyamide (PA) blocks and polyethylene glycol (PEG) blocks, (c) functionalized polyolefin, and (d) polyolefin is those defined above.

[0121] In some embodiments, the first component and the second component can be contained, stored or packaged in separate containers, respectively, and such separate containers of the two components can optionally be packaged together by any suitable packaging form. Alternatively, the containers of the two components can be provided separately without any common packaging.

[0122] Articles containing or made from the composition and methods for preparing the article

[0123] The invention also relates to an article comprising or made from a composition according to the invention, and a method for producing said article.

[0124] The articles can be prepared using any method known in the art, such as by extrusion, injection, molding, and the like.

[0125] In some embodiments, the article is a film, a sheet, or a bag, preferably a film.

[0126] In some embodiments, the article is an article suitable for food packaging.

[0127] In some embodiments, the thickness of the article as a film, sheet or bag (preferably a film) is generally 5 to 500 μm, preferably 10 to 250 μm, more preferably 20 to 100 μm, for example 20 to 40 μm, or 20 to 30 μm.

[0128] In some embodiments, the method of making an article comprises the steps of:

[0129] - a composition obtained by a process as defined above; and

[0130] - Extruding or molding the composition into a film or sheet.

[0131] The films obtained from the composition according to the invention are non-porous and breathable, in other words they are permeable to water vapour but impermeable to water and, more generally, permeable to gases but impermeable to liquids.

[0132] The articles obtained from the composition according to the invention, in particular in the form of films, give improved MVTR values. The improved MVTR values ​​can be between 8 and 500 g / m2 / 24 hours, preferably between 10 and 500 g / m2 / 24 hours, more preferably between 12 and 500 g / m2 / 24 hours, at 23°C, for a relative humidity level of 50%, at a thickness of 25 μm, measured according to the method described in ASTM standard E 96 B-water method. Too low MVTR values ​​may lead to mold growth, while too high MVTR values ​​may lead to wilting of fruits or vegetables. Such films enable an ideal environment to be achieved in the packaging of fresh products such as fruits and vegetables. Depending on the type of fruit or vegetable, the film can be appropriately selected according to the MVTR value.

[0133] The gas selectivity is defined as the ratio of the permeabilities of two pure gases, respectively measured under the same conditions. 2 With O 2 The permeability ratio is typically below 12 and preferably between 4 and 10, these values ​​being valid at 0% relative humidity (0% RH) and 23°C.

[0134] The films obtained from the compositions according to the invention give improved processability and higher tensile strength. The tensile strength (MD) measured according to the method described in ASTM D 638 Type IV may be higher than 10 MPa, preferably higher than 14 MPa, more preferably higher than 18 MPa. Such films facilitate the manufacturing and processing steps.

[0135] These films can be prepared using any method known in the art, for example by extrusion or molding. The thickness of the film is generally 5 to 500 μm, preferably 10 to 250 μm, more preferably 20 to 100 μm, for example 20 to 40 μm, or 20 to 30 μm. The film can be associated with other films and / or carriers. For example, the film obtained by the composition according to the invention can be coextruded or laminated on a carrier (for example a mesh made of polyethylene or PVC).

[0136] In some embodiments, the articles made from the compositions according to the invention are used for packaging, such as food packaging and packaging for fresh products (e.g., fruits, vegetables, freshly cut meat and fish). For example, the film obtained from the compositions according to the invention can be only a part of the packaging, the other parts being made from any other material.

[0137] The invention also relates to the use of a composition as defined above for food packaging.

[0138] The following examples illustrate the present invention without limiting it.

[0139] Example

[0140] The following examples illustrate the present invention without limiting it.

[0141] Compositions having the blending ratios summarized in Table 1 were prepared. Specifically, (a) PA, (b) PA / PEG PEBA, and (c) functionalized polyolefin were blended and mixed into pellets using a twin-screw extruder. The resulting pellets were blended with (d) polyolefin and extruded into films. For Examples 12 and 13, styrene maleic anhydride (SMA) was further blended with (a) PA, (b) PA / PEG (PEBA), and (c) functionalized polyolefin and mixed into pellets, and the pellets were blended with (d) polyolefin and extruded into films.

[0142] Table 1

[0143]

[0144] Unit: Weight%

[0145] - Rilsan® BESNO TL: Polyamide 11 (PA11), available from ARKEMA

[0146] -PEBA: PA11 / PEG 1000 / 1500 (Mn: PA 11 block with a molecular weight of 1000 g / mol and PEG block with a molecular weight of 1500 g / mol)

[0147] - Lotader® AX8840: a random copolymer of ethylene and glycidyl methacrylate (GMA), available from SK functional polymer

[0148] - Lotader® LX4110: a random terpolymer of ethylene, acrylic acid ester and maleic anhydride (MAH), available from SK functional polymer

[0149] - Lotryl® 29MA03T: Random ethylene-methyl acrylate copolymer from SK functional polymer

[0150] -Ultzex® 2022L: Linear low density polyethylene (LLDPE), purchased from Prime polymer

[0151] -SMA: Styrene maleic anhydride, purchased from Polyscope Polymers BV

[0152] For the films of Examples 1-16 prepared as above, measurements were performed under the following conditions:

[0153] -Machine: GTR-30XADJ4, G2700T

[0154] -Test surface: 15.2 x 10 -4 m²

[0155] -Detection: gas chromatography, thermal conductivity (TCD)

[0156] - Temperature: 23℃

[0157] -Relative humidity: 0%

[0158] -Carrier gas: helium (pressure: 1 bar)

[0159] -Diffusion gas: O 2 , CO 2 (Pressure: 1 bar each)

[0160] The film's CO absorption was measured at a film thickness of 25 μm using gas chromatography at a temperature of 23° C. and a relative humidity of 0% according to the method described in JIS K7126. 2 and O 2 The permeability of CO 2 and O 2 The results for the permeability are given in Table 2 below in ml / m² / 24h atm.

[0161] Moisture Vapor Transmission Rate (MVTR) indicates the amount of water vapor that passes through a film or structure over a period of 24 hours. For a 25 μm thick film prepared as above, MVTR was measured in a Heraeus Votsch oven at 23°C, 50% RH according to the method described in ASTM E 96B-Water Method. The results of MVTR are given in Table 2 below in g / m² / 24h.

[0162] In addition, the tensile strength (MD) of the films of the examples prepared as above was measured. The measurement was carried out using the method described in ASTM D 638 Type IV. The results are given in MPa in Table 2 below.

[0163] For the examples prepared as above, the minimum thickness of the films was measured. The measurement was performed using a micrometer according to standard ISO 4591. For the purposes of this application, "minimum thickness" means the minimum thickness of the film that can be continuously achieved without breaks during the film extrusion process.

[0164] Table 2

[0165]

[0166] As can be seen from Table 2, compared with the membranes of Comparative Examples 1, 2, 5 and 6, the membranes of Examples 3, 4, 7-12 provide CO 2 and O 2 The compositions of the present invention advantageously provide films having an ideal MVTR range suitable for packaging fresh products.

Claims

1. A composition comprising: (a) polyamide (PA), (b) a polymer having a polyamide (PA) block and a polyethylene glycol (PEG) block, (c) a functionalized polyolefin, and (d) polyolefins, The weight ratio of (a+b) / (c+d) is <1.

2. A composition according to claim 1, wherein the weight ratio b / (a+b+c+d) is equal to or less than 0.5, typically between 0.05 and 0.

5.

3. The composition according to any of the preceding claims, wherein the polyamide in (a) is or comprises PA6, PA6.6, PA6.10, PA10.10, PA10.12, PA11, PA12, PA6.12 and / or PA12.12, preferably PA10.10, PA10.12, PA11, PA12, PA6.12, PA11.12 and / or PA12.

12.

4. The composition according to any of the preceding claims, wherein the polyamide blocks in polymer (b) are or comprise PA6, PA6.6, PA6.10, PA10.10, PA10.12, PA11, PA12, PA6.12 and / or PA12.12, preferably PA10.10, PA10.12, PA11, PA12, PA6.12, PA11.12 and / or PA12.

12.

5. The composition according to any one of the preceding claims, wherein the average carbon content of the repeating units of the polyamide (a) and / or the polyamide blocks in the polymer (b) is at least 8, preferably 8 to 14, more preferably 10 to 12.

6. The composition according to any one of the preceding claims, wherein the polyamide of the polyamide blocks in (b) is the same as the polyamide in (a).

7. A composition according to any one of the preceding claims, wherein the polymer (b) comprises at least 30 wt. %, preferably at least 40 wt. %, more preferably at least 50 wt. % polyethylene glycol (PEG) relative to the total weight of the polymer (b).

8. A composition according to any one of the preceding claims, wherein the functionalized polyolefin in (c) is or comprises an ethylene / butyl acrylate / maleic anhydride copolymer or an ethylene / ethyl acrylate / glycidyl methacrylate copolymer, preferably a copolymer of ethylene and glycidyl methacrylate (GMA).

9. The composition according to any one of the preceding claims, wherein the polyolefin in (d) is or comprises ethylene methyl acrylate copolymer or LLDPE.

10. A method for preparing a composition comprising the steps of blending: (a) polyamide (PA), (b) a polymer having a polyamide (PA) block and a polyethylene glycol (PEG) block, (c) a functionalized polyolefin, and (d) polyolefins, The weight ratio of (a+b) / (c+d) is less than 1.

11. The method according to claim 11, comprising the step (i) of blending (a), (b), (c) to obtain a base polymer blend or mixture, and the step (ii) of blending (d) a polyolefin into the base polymer blend or mixture.

12. An article, preferably an article suitable for food packaging, comprising or made from the composition according to any one of claims 1 to 9, preferably the article is a film, a sheet or a bag.

13. The article according to claim 12, having an MVTR of 8 to 500 g / m2 / 24 hours, preferably 10 to 500 g / m2 / 24 hours, more preferably 12 to 500 g / m2 / 24 hours, the MVTR being measured at 23°C, for a relative humidity level of 50% at a thickness of 25 μm.

14. A method for preparing a product according to claim 12 or 13, wherein The following steps are involved: - the composition is obtained by the method according to any one of claims 10 to 11; and - Extruding or molding the composition into a film or sheet.

15. Use of the preparation according to claim 12 or 13 for food packaging.

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