Multilayer packaging film

Abstract

The present invention relates to a biodegradable multilayer packaging film comprising at least one layer A and one layer B, wherein the layers are arranged in an A / B / A sequence. The multilayer film comprises a biodegradable polyester, a polyhydroxyalkanoate, and optionally an antifogging agent.

Description

Technical Field

[0001] The present invention relates to a biodegradable multilayer packaging film containing a biodegradable polyester, polyhydroxyalkanoate and optionally an anti-fog agent.

Background Art

[0002] Packaging films (known as "foils" or "films") are known in the industry and literature. Usually, the thickness of these films is 3 to 50 μm, and they are used for packaging applications, for example, before putting food in a refrigerator or packing it in a container. It is not easy to obtain an optimal packaging film. This is because, in its use, many special technical characteristics as shown below are required. - Adhesiveness The property that the film adheres to itself and to other non-sticky surfaces without using an adhesive is essential. This property allows the user to wrap the film around an object (e.g., food on a plate) in one or multiple layers, and as a result, it becomes possible to seal. - Transparency Transparency is an indispensable feature, which enables the user to identify the packaged object without peeling off the film. From a commercial perspective, it is highly desirable that the film-wrapped product can be visually recognized as clearly as possible. Therefore, it is particularly important that the film does not become cloudy over time. - Mechanical properties Mechanical properties are physical properties that satisfy the mechanical performance and strength of the packaging material. In particular, the tensile strength (MPa), elongation at break (%), and modulus of elasticity (MPa) in both the machine direction (MD) and the transverse direction (TD) are measured. - Stability over time (storage life) It is essential to use a polyester that imparts good stability over time to the film so that the product can be stored for as long as possible, at least for 6 months, preferably for 1 year. - Anti-fog Anti-fogging properties are a particularly valued feature in the market. This prevents the condensation of tiny water droplets that typically fog up the packaging of fresh and refrigerated products such as meats and vegetables.

[0003] EP2550330A1 describes polymer blends, cling films, and methods for obtaining them. Specifically, it describes films containing aliphatic-aromatic polyesters with a low aromatic content. EP2499189B1 describes a method for manufacturing a multilayer film containing 45-70% w / w aliphatic-aromatic polyester and 30-55% w / w PLA, with a blow-up ratio of 4:1 or less, where the outer layer contains PLA and at least the core layer consists of 20-70% w / w aliphatic-aromatic polyester and 30-80% w / w PLA. EP2331634B1 describes a biodegradable polymer mixture comprising 40-95% by weight of aliphatic or aliphatic-aromatic polyester, 5-60% by weight of polyalkylene carbonate, particularly polypropylene carbonate, and 0.1-5% by weight of copolymer containing epoxy groups based on styrene, acrylic acid esters, and / or methacrylic acid esters, based on the sum of the aforementioned two components. The potential use of antifogging agents is described in all of these patents. EP3642268B1 describes a multilayer film containing an anti-fogging agent, characterized in that the intermediate layer contains starch. In PCT / EP2021 / 067193, the applicant has optimized the properties of the packaging film not only in terms of anti-fogging but also in terms of improved dispensing, which is desirable for use in industrial packaging machines. [Overview of the project] [Problems that the invention aims to solve]

[0004] To obtain a film that truly performs in its desired end application, it is necessary to impart anisotropy to the film's tear strength. This is a necessary condition for ensuring the "straight cut" capability that is valued in household applications. Anisotropy refers to a state where the tear strength in the transverse direction (TD) is low, while the tear strength in the longitudinal direction (MD) is higher than that in the transverse direction (TD). Furthermore, even in the presence of an anti-fogging agent, good transparency, excellent adhesion, and good optical properties must be ensured. To solve the above problems, it was found that a multilayer film with specific specifications was necessary. [Means for solving the problem]

[0005] Therefore, one aspect of the present invention is a multilayer packaging film comprising at least one layer A and one layer B, having an A / B / A arrangement of these layers, wherein layer A is: i. A biodegradable aliphatic aromatic polyester comprising 95-100% by weight of the total of components i-ii, having a melt strength of 0.007N-0.04N: -Mn≧40000 -Mw / q≦90000 Here, Mn and Mw are the number-average molecular weight and weight-average molecular weight, respectively, and "q" is the weight percentage of polyester oligomers having a GPC molecular weight of 10,000 or less. The melt strength was determined according to ISO 16790:2005, using a capillary with a diameter of 1 mm and L / D = 30 at 180°C, γ = 103.7 s⁻¹, and a constant acceleration of 6 mm / sec. 2 The biodegradable aliphatic aromatic polyester was measured at an elongated length of 110 mm, and "Mn" and "Mw" were measured by gel permeation chromatography (GPC). ii. An antifogging agent in an amount of 0 to 5% by weight relative to the total of components i to ii, wherein the antifogging agent is selected from an ester of a polyfunctional alcohol, preferably a condensation product of a polyfunctional alcohol and a fatty acid, provided that the ester is not a stearate, and the antifogging agent Including layer B is: iii. At least one type of polyester in an amount of 60 to 90% by weight relative to the sum of components iii to v: a. For all dicarboxylic acid components: a1) 30-60 mol% of at least one aromatic dicarboxylic acid-derived unit, a2) 70-40 mol% of at least one saturated aliphatic dicarboxylic acid-derived unit, (a3) 0-5 mol% of at least one unit derived from an unsaturated aliphatic dicarboxylic acid, A dicarboxylic acid component containing, b. The following are all diol components: b1) 95-100 mol% of at least one saturated aliphatic diol-derived unit, b2) 0-5 mol% of at least one unsaturated aliphatic diol-derived unit, Diol components containing, Polyester containing, iv. One or more polyhydroxyalkanoates in an amount of 10 to 40% by weight relative to the total of components iii to v., v. At least one crosslinking agent and / or chain extender in an amount of 0 to 1% by weight relative to the total of components iii. to v., Includes, A further characteristic is that the content of component iv in the multilayer film is 1.6 to 11% by weight relative to components i to v.

[0006] The multilayer packaging film according to the present invention has a total thickness of 3 to 50 μm, preferably 6 to 14 μm, and more preferably 8 to 10 μm.

[0007] The polyester (component i.) that can be used in the production of layer A of the multilayer film according to the present invention is, for example, already described in the patents PCT / EP2021 / 063718 and EP2632970B1 in the name of the present applicant, which refer to the characteristics and preparation methods of the polyester.

[0008] Preferably, the polyester used in preparing layer A of the film according to the present invention has a gel fraction of less than 5%, more preferably less than 3%, and even more preferably less than 1%. The gel fraction is determined by immersing the polyester sample (X1) in chloroform, filtering the mixture through a 25-45 μm sieve, and measuring the weight of the material (X2) remaining on the filter screen. The gel fraction is determined as the ratio of the weight of the material thus obtained to the weight of the sample, i.e., (X2 / X1) × 100. The polyester in layer A is an aliphatic aromatic polyester.

[0009] In particular, the aromatic moiety mainly consists of at least one polyfunctional aromatic acid, and the aliphatic moiety includes at least one aliphatic dicarboxylic acid and at least one aliphatic diol. Polyfunctional aromatic acids include phthalic acid-type dicarboxylic acid aromatic compounds and their esters, as well as heterocyclic dicarboxylic acid aromatic compounds and their esters of renewable origin. Terephthalic acid and its esters are particularly preferred.

[0010] Aliphatic dicarboxylic acids are defined as dicarboxylic acids having 2 to 22 carbon atoms in their main chain and their esters. Dicarboxylic acids derived from renewable raw materials, their esters and mixtures thereof are preferred, and these include succinic acid, adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, undecanediic acid, dodecanediic acid, brassic acid and mixtures thereof. In a particularly preferred embodiment, the aliphatic dicarboxylic acid of the biodegradable polyester for producing a film having an antifogging agent according to the present invention contains at least 50 mol% of azelaic acid, sebacic acid, or adipic acid relative to the total moles of the aliphatic dicarboxylic acid.

[0011] In the polyester used in the film layer A according to the present invention, the diol is understood to be a compound having two hydroxyl groups. C2~C 13 Aliphatic diols are preferred. Examples of aliphatic diols include: 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, 2-methyl-1,3-propanediol, dianhydrosorbitol, dianhydromannitol, dianhydroiditol, cyclohexanediol, cyclohexanemethanediol, and mixtures thereof. Among these, 1,4-butanediol, 1,3-propanediol, 1,2-ethanediol, and mixtures thereof are particularly preferred. A particularly preferred form of the diol is 1,4-butanediol.

[0012] Component i. is characterized by a polyfunctional aromatic acid content of 30 to 70 mol%, preferably 40 to 60 mol%, based on the total molar content of the dicarboxylic acid. Advantageously, branched compounds may be added to component i. in an amount of less than 0.5 mol%, preferably less than 0.2 mol%, based on the total molar content of the dicarboxylic acid. These branched compounds are selected from the group of polyfunctional molecules such as polyacids, polyols, and mixtures thereof.

[0013] Examples of polyacids are: 1,1,2-ethanetricarboxylic acid, 1,1,2,2-ethanetetracarboxylic acid, 1,3,5-pentatricarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, malic acid, citric acid, tartaric acid, 3-hydroxyglutaric acid, mucic acid, trihydroxyglutaric acid, hydroxyisophthalic acid, their derivatives, and mixtures. Examples of polyols are: glycerol, hexanetriol, pentaerythritol, sorbitol, trimethylolethane, trimethylolpropane, mannitol, 1,2,4-butanetriol, xylitol, 1,1,4,4-tetrakis(hydroxymethyl)cyclohexane, arabitol, adonitol, iditol, and mixtures thereof.

[0014] The number-average molecular weight Mn of the component i. is preferably more than 20,000, and more preferably more than 40,000. Regarding the polydispersity index Mw / Mn of the molecular weight, it is preferably 1.5 to 10, more preferably 1.6 to 5.0, and even more preferably 1.8 to 2.7. The number-average molecular weight Mn and weight-average molecular weight Mw may be measured by gel permeation chromatography (GPC). The measurement can be carried out by maintaining the chromatography system at 40 °C, arranging two columns in series (particle diameters 5 μm and 3 μm, mixed porous), using a refractive index detector, using chloroform as the eluent (flow rate 0.5 ml / min), and using polystyrene as the standard substance.

[0015] The weight percentage ("q") of the polyester oligomer having a molecular weight of 10,000 or less is calculated according to the following formula: "q" = (P1.F2) / F1 The weight percentage of the polyester oligomer having a GPC molecular weight of 10,000 or less was measured by the following method. A polyester sample (about 3 - 4 g, F1) was put into a 200 ml flask together with 30 ml of chloroform. After the polyester was completely dissolved, 100 ml of a 1:1 v / v solution of methanol and acetone was added, and then the mixture was stirred for 2 hours. Then, the mixture was filtered through a filter paper with a pore size of 8 μm. The polymer remaining on the filter was rinsed with acetone. The methanol solution containing 1:1 v / v acetone was completely evaporated by heating to 70 °C under an air stream, and the weight of the remaining solid fraction was recorded (F2). A sample of the solid fraction (about 10 mg) was dissolved in 10 ml of chloroform and analyzed by GPC according to the above method. Based on the molecular weight distribution curve recorded by the GPC instrument, the ratio (P1) of the polymer chains having a molecular weight of 10,000 or less was determined.

[0016] Preferably, component i has an intrinsic viscosity greater than 0.3 dl / g (measured using an Ubbelohde viscometer for a solution having a concentration of 0.2 g / dl in CHCl3 at 25°C), preferably 0.3 to 2.0 dl / g, and more preferably 0.4 to 1.2 dl / g. The terminal acid group content of component i is preferably less than 100 meq / kg, more preferably less than 60 meq / kg, and even more preferably less than 40 meq / kg. The content of terminal acid groups can be measured by methods known in the art, for example, according to the method described in WO2017 / 216150.

[0017] The aforementioned component i. is biodegradable. In the sense of the present invention, a biodegradable polymer means a polymer that exhibits biodegradability in accordance with EN13432:2002. The aforementioned component i. can be synthesized by any method known in the art. In particular, it can be advantageously obtained using a polycondensation reaction. Advantageously, the synthesis process can be carried out in the presence of a suitable catalyst. Examples of suitable catalysts include organometallic tin compounds, such as stanic acid derivatives; titanium compounds, such as orthobutyl titanate; aluminum compounds, such as triisopropylaluminum; and compounds and mixtures thereof of antimony, zinc, and zirconium.

[0018] Layer A may optionally contain one or more anti-fogging agents (up to 5% by weight of the total of components i. to ii.). In a particularly preferred embodiment, there is an antifogging agent constituting component ii of layer A according to the present invention, the antifogging agent is selected from an ester of a polyfunctional alcohol, preferably from a condensation product of a polyfunctional alcohol and a fatty acid, provided that the ester is not an ester of stearic acid.

[0019] Suitable compounds that can be used as anti-fogging agents are polyglyceryl laurate, sorbitan monooleate, sorbitan trioleate, and glyceryl monopalmitate. In a preferred embodiment of the present invention, component ii of layer A is selected from fatty acid esters having 8 to 18 carbon atoms, more preferably 12 to 16 carbon atoms. In a particularly preferred embodiment of the present invention, the fatty acid ester is selected from polyglyceryl laurate and sorbitan monolaurate. In the present invention, with respect to the anti-fogging agent, the term "ester" means either a pure ester or a mixture of esters with two or more individual esters that are different from each other.

[0020] The ester characterizing the antifogging agent according to the present invention comprises at least 20% by weight, preferably 30% by weight, and more preferably 60% by weight, of a partial ester of a polyfunctional alcohol, relative to the weight of the ester itself. In some cases, the partial ester of the polyfunctional alcohol or the condensation product of the polyfunctional alcohol and the fatty acid has been found to be up to 80% by weight or 90% by weight relative to the ester.

[0021] The antifogging agent can be added directly to the polyester at the desired final concentration during the extrusion process, or it can be added via a hopper in the form of a "masterbatch" during the film forming process. In this invention, "masterbatch" means polyester pellets having a high concentration of antifogging agent. The concentration of the additive in the "masterbatch" is typically 10%. Preferably, the anti-fogging agent in the multilayer film according to the present invention is biodegradable in accordance with the standards set forth in EN13432. More preferably, the anti-fogging agent achieves 10-60% biodegradation within a 10-day timeframe within 28 days of testing according to OECD Method 301B.

[0022] The film layer A according to the present invention may be obtained by a reactive extrusion process. Preferably, the reactive extrusion process is carried out by adding a peroxide, epoxide, or carbodiimide. Preferably, the reactive extrusion process is carried out using an amount of peroxide ranging from 0.001 to 0.2% by weight, preferably 0.01 to 0.1% by weight, relative to the total amount of components i to ii supplied to the reactive extrusion process. With regard to the addition of epoxides, these are preferably used in an amount of 0.1 to 2% by weight, more preferably 0.2 to 1% by weight, of the total of components i. to ii. supplied to the reactive extrusion process. When carbodiimides are used, they are preferably used in an amount of 0.05 to 2% by weight, more preferably 0.1 to 1% by weight, of the total of components i. to ii. supplied to the reactive extrusion process. A mixture of the peroxide, epoxide, and carbodiimide can also be used.

[0023] Examples of peroxides that can be advantageously used are selected from dialkylperoxides, and specific examples include benzoyl peroxide, lauroyl peroxide, isononanoyl peroxide, di-(t-butylperoxyisopropyl)benzene, t-butyl peroxide, dicumyl peroxide, α,α'-di(t-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexa-3-yne, di(4-t-butylcyclohexyl)peroxydicarbonate, dicetyl peroxycarbonate, dimyristyl peroxycarbonate, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxinane, di(2-ethylhexyl)peroxycarbonate, and mixtures thereof.

[0024] Examples of epoxides that can be advantageously used include all polyepoxides from epoxidized oils and / or styrene-glycidyl ether-methyl methacrylate, glycidyl ether-methyl methacrylate, having a molecular weight in the range of 1,000 to 10,000 and a number of epoxides per molecule of 1 to 30, preferably in the range of 5 to 25, as well as epoxides selected from the group including diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether, 1,2-epoxybutane, polyglycerol polyglycidyl ether, isoprene epoxide, and alicyclic diepoxides, 1,4-cyclohexanedimethanol diglycidyl ether, glycidyl 2-methylphenyl ether, glycerol propoxylate triglycidyl ether, 1,4-butanediol diglycidyl ether, sorbitol polyglycidyl ether, glycerol diglycidyl ether, tetraglycidyl ether of metaxylenediamine, and diglycidyl ether of bisphenol A, and mixtures thereof.

[0025] A catalyst may be used to increase the reactivity of the reactive group. In the case of polyepoxides, for example, a fatty acid salt can be used. Calcium stearate and zinc stearate are particularly preferred.

[0026] Examples of carbodiimides that can be advantageously used include poly(cyclooctylenecarbodiimide), poly(1,4-dimethylcyclohexylenecarbodiimide), poly(cyclohexylenecarbodiimide), poly(ethylenecarbodiimide), poly(butylenecarbodiimide), poly(isobutylenecarbodiimide), poly(nonylenecarbodiimide), poly(dodecylenecarbodiimide), poly(neopentylenecarbodiimide), poly(1,4-dimethylenephenylenecarbodiimide), poly(2,2',6,6'-tetraisopropyldiphenylenecarbodiimide) (Stabaxol® D), poly(2,4,6-triisopropyl-1-phenylenecarbodiimide) (Stabaxol® P-100), and poly(2,6-diisopropyl-1,3-phenylenecarbodiimide) ( Selected from the group comprising Stabaxol® P), poly(tolylcarbodiimide), poly(4,4'-diphenylmethanecarbodiimide), poly(3,3'-dimethyl-4,4'-biphenylenecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(3,3'-dimethyl-4,4'-diphenylmethanecarbodiimide), poly(naphthylenecarbodiimide), poly(isophoronecarbodiimide), poly(cumenecarbodiimide), p-phenylenebis(ethylcarbodiimide), 1,6-hexamethylenebis(ethylcarbodiimide), 1,8-octamethylenebis(ethylcarbodiimide), 1,10-decamethylenebis(ethylcarbodiimide), 1,12-dodecamethylenebis(ethylcarbodiimide), and mixtures thereof.

[0027] For the purposes of the present invention, layer A of the multilayer film does not contain one or more polyhydroxyalkanoates.

[0028] In a particularly preferred embodiment, layer A of the multilayer film is: i. A biodegradable aliphatic aromatic polyester in an amount of 95 to 100% by weight relative to the total of components i to ii, having a melt strength of 0.007 N to 0.04 N, and containing at least one dicarboxylic acid and at least one diol unit, -Mn≧40000 -Mw / q≦90000 Here, Mn and Mw are the number-average molecular weight and weight-average molecular weight, respectively, and "q" is the weight percentage of polyester oligomers having a GPC molecular weight of 10,000 or less. Melt strength is measured according to ISO 16790:2005, at 180°C, γ=103.7s-1, using a capillary with a diameter of 1 mm and L / D=30, at a constant acceleration of 6 mm / sec2 and an elongation length of 110 mm. "Mn" and "Mw" are measured by gel permeation chromatography (GPC) for a biodegradable aliphatic aromatic polyester. ii. An antifogging agent in an amount of 0 to 5% by weight relative to the total of components i to ii, wherein the antifogging agent is selected from an ester of a polyfunctional alcohol, preferably a condensation product of a polyfunctional alcohol and a fatty acid, provided that the ester is not a stearate. The anti-fogging agent (component ii.) is present in an amount of 0.2 to 5%, preferably 1 to 3%, of the total content of components i. to ii. Layer B of the multilayer film according to the present invention is: iii. At least one type of polyester in an amount of 60 to 90% by weight relative to the sum of components iii to v: For all dicarboxylic acid components: a1) 30-60 mol% of at least one aromatic dicarboxylic acid-derived unit, a2) 70-40 mol% of at least one saturated aliphatic dicarboxylic acid-derived unit, (a3) A dicarboxylic acid component comprising at least one unsaturated aliphatic dicarboxylic acid-derived unit in 0-5 mol%, For all diol components: b1) 95-100 mol% of at least one saturated aliphatic diol-derived unit, (b2) At least one mole of unsaturated aliphatic diol-derived units, Diol components containing, Polyester containing, iv. 10 to 40% by weight of one or more polyhydroxyalkanoates relative to the total of components iii) to v), v. comprising 0 to 1% by weight of at least one crosslinking agent and / or chain extender relative to the total of components i) to v).

[0029] Component iii of layer B of the multilayer film according to the present invention is preferably present in an amount of 71 to 85% by weight, and more preferably in an amount of 75 to 81% by weight, relative to the total of components iii to v.

[0030] The aromatic dicarboxylic acid in component a1 is preferably selected from phthalic acid-type aromatic dicarboxylic acids, preferably terephthalic acid or isophthalic acid and their esters, salts, and mixtures, and more preferably terephthalic acid and its esters, salts, and mixtures. The aromatic dicarboxylic acid in component a1 is present in an amount of 30 to 60 mol%, preferably 40 to 55 mol%, more preferably 42 to 52 mol%, and even more preferably 45 to 48 mol%, relative to the total dicarboxylic acid components.

[0031] The saturated aliphatic dicarboxylic acid in component a2 is preferably selected from saturated aliphatic dicarboxylic acids of C2-C24, preferably C4-C13, more preferably C4-C11, and their C1-C24, preferably C1-C4 alkyl esters, their salts, and mixtures thereof. Preferably, the saturated aliphatic dicarboxylic acid is selected from succinic acid, 2-ethyl succinic acid, glutaric acid, 2-methylglutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanediic acid, dodecanediic acid, brassic acid, and their C1-C24 alkyl esters. In a preferred embodiment of the present invention, the saturated aliphatic dicarboxylic acid includes a mixture comprising succinic acid, adipic acid, azelaic acid, sebacic acid, their C1-C24, preferably C1-C4 alkyl esters, and mixtures thereof. In a preferred embodiment, the mixture comprises or consists of at least adipic acid and azelaic acid, and contains azelaic acid in an amount of 5 to 65 mol%, more preferably 10 to 40 mol%, of the total amount of all saturated aliphatic dicarboxylic acids present. The saturated aliphatic dicarboxylic acid in component a2 is present in an amount of 70 to 40 mol%, preferably 60 to 45 mol%, more preferably 58 to 48 mol%, and even more preferably 55 to 52 mol%, relative to the total dicarboxylic acid components.

[0032] The unsaturated aliphatic dicarboxylic acid in component a3 is preferably selected from itaconic acid, fumaric acid, 4-methylene-pimelic acid, 3,4-bis(methylene)nonanandioic acid, 5-methylene-nonanandioic acid, their C1-C24, preferably C1-C4 alkyl esters, their salts, and mixtures thereof. In a preferred embodiment of the present invention, the unsaturated aliphatic dicarboxylic acid comprises a mixture containing at least 50 mol%, preferably more than 60 mol%, and more than 65 mol%, of itaconic acid and its C1-C24, preferably C1-C4 esters. More preferably, the unsaturated aliphatic dicarboxylic acid consists of itaconic acid.

[0033] The saturated aliphatic diol in component b1 is preferably selected from polyalkylene glycols with a molecular weight of 100 to 4000, such as 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, 2-methyl-1,3-propanediol, dianhydrosorbitol, dianhydromannitol, dianhydroiditol, cyclohexanediol, cyclohexanemethanediol, dialkylene glycol, and polyethylene glycol, polypropylene glycol, and mixtures thereof. Preferably, the diol component contains at least 50 mol% of one or more diols selected from 1,2-ethanediol, 1,3-propanediol, and 1,4-butanediol. More preferably, the diol component contains or consists of 1,4-butanediol.

[0034] The unsaturated aliphatic diol in component b2 is preferably selected from cis-2-butene-1,4-diol, trans-2-butene-1,4-diol, 2-butyne-1,4-diol, cis-2-pentene-1,5-diol, trans-2-pentene-1,5-diol, 2-pentyne-1,5-diol, cis-2-hexen-1,6-diol, trans-2-hexen-1,6-diol, 2-hexyn-1,6-diol, cis-3-hexen-1,6-diol, trans-3-hexen-1,6-diol, and 3-hexen-1,6-diol.

[0035] The molecular weight Mn of component iii is preferably greater than 20,000, and more preferably greater than 40,000. The polydispersity index Mw / Mn of the molecular weight is preferably 1.5 to 10, more preferably 1.6 to 5.0, and even more preferably 1.8 to 2.7.

[0036] Component iv of layer B of the multilayer film according to the present invention contains one or more polyhydroxyalkanoates in an amount of 10 to 40% by weight, more preferably 15 to 29% by weight, and even more preferably 19 to 25% by weight, relative to the total of components iii to v. The polyhydroxyalkanoate (component iv.) is preferably selected from the group consisting of lactate polyester, polyhydroxybutyric acid, polyhydroxybutyric acid-valeric acid, polyhydroxybutyric acid-propanoic acid, polyhydroxybutyric acid-hexanoic acid, polyhydroxybutyric acid-decanoic acid, polyhydroxybutyric acid-dodecanoic acid, polyhydroxybutyric acid-hexadecanoic acid, polyhydroxybutyric acid-octadecanoic acid, and poly-3-hydroxybutyric acid-4-hydroxybutyric acid. Preferably, the polyhydroxyalkanoate in the composition contains at least 70% by weight of one or more lactate polyesters. In a particularly preferred embodiment of the present invention, component iv. consists entirely of one or more lactate polyesters.

[0037] In a preferred embodiment of the present invention, the lactic acid polyester (component iv.) has a melting temperature (Tm) of 135 to 160°C and a glass transition temperature (Tg) of 45 to 75°C. Examples of commercially available lactic acid polyesters having these properties include, for example, the biopolymer products Ingeo® 4043D, Ingeo® 3052D, and Luminy® LX175.

[0038] The melting temperature Tm and glass transition temperature Tg can be advantageously measured by differential scanning calorimetry (DSC) using a Perkin Elmer Pyris Diamond calorimeter under the following conditions: • Maintain isothermal temperature at -20°C for 60 seconds. • First scan from -20°C to 200°C at 20°C / min • Maintain isothermal temperature at 200°C for 60 seconds. • Second scan from 200°C to -20°C at a rate of 10°C / min • Maintain isothermal temperature at -20°C for 60 seconds. • Third scan from -20°C to 200°C at 20°C / min The melting temperature (Tm) is determined from the first scan, and the glass transition temperature (Tg) is determined from the third scan.

[0039] Preferably, the lactic acid polyester has a shear viscosity of 150 to 1700 Pa.s (measured according to ASTM standard D3835, with T=190°C, shear strain rate=141.6s⁻¹, D=1mm, L / D=10, and dry material containing less than 400 ppm of water).

[0040] For the purposes of the present invention, component iv is included in the multilayer film in an amount of 1.6 to 11% by weight, preferably 4 to 9% by weight, relative to components i to v. The composition of layer B of the multilayer film according to the present invention contains at least one crosslinking agent and / or chain extender (component v) in an amount of 0 to 1% by weight, preferably 0.05 to 0.5% by weight, and more preferably 0.1 to 0.3% by weight, relative to the total amount of components i to v. The crosslinking agent and / or chain extender is selected from difunctional and / or polyfunctional compounds having a carbodiimide group or an epoxide group, or mixtures thereof.

[0041] The bifunctional and polyfunctional compounds having a carbodiimide group that are preferably used in the compositions according to the present invention are poly(cyclooctylenecarbodiimide), poly(1,4-dimethylcyclohexylenecarbodiimide), poly(cyclohexylenecarbodiimide), poly(ethylenecarbodiimide), poly(butylenecarbodiimide), poly(isobutylenecarbodiimide), poly(nonylenecarbodiimide), poly(dodecylenecarbodiimide), poly(neopentylenecarbodiimide), poly(1,4-dimethylenephenylenecarbodiimide), poly(2,2',6,6'-tetraisopropyldiphenylenecarbodiimide) (Stabaxol® D), poly(2,4,6-triisopropyl-1,3-phenylenecarbodiimide) (Stabaxol® P-100), poly(2,6-diisopropyl-1, 3-Phenylenecarbodiimide (Stabaxol® P), poly(tolylcarbodiimide), poly(4,4'-diphenylmethanecarbodiimide), poly(3,3'-dimethyl-4,4'-biphenylenecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(3,3'-dimethyl-4,4'-diphenylmethanecarbodiimide), poly(naphthyl Selected from phenylepinebi(ethylcarbodiimide), poly(isophoronecarbodiimide), poly(cumenecarbodiimide), p-phenylenebis(ethylcarbodiimide), 1,6-hexamethylenebis(ethylcarbodiimide), 1,8-octamethylenebis(ethylcarbodiimide), 1,10-decamethylenebis(ethylcarbodiimide), 1,12-dodecamethylenebis(ethylcarbodiimide), and mixtures thereof.

[0042] Examples of bifunctional and polyfunctional compounds having epoxy groups that can be advantageously used in compositions according to the present invention include all polyepoxides from epoxidized oils and / or styrene-glycidyl-methyl methacrylate or glycidyl-methacrylate, having a molecular weight in the range of 1,000 to 10,000 and a number of epoxides per molecule of 1 to 30, preferably in the range of 5 to 25, as well as epoxides selected from the group including diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether, 2-epoxybutane, polyglycerol polyglycidyl ether, isoprene epoxide and alicyclic diepoxide, 1,4-cyclohexanedimethanol diglycidyl ether, glycidyl 2-methylphenyl ether, glycerol propoxylate triglycidyl ether, tetraglycidyl ether of metaxylenediamine and diglycidyl ether of bisphenol A, and mixtures thereof.

[0043] A catalyst may be used in combination with the aforementioned difunctional and polyfunctional compounds having carbodiimide groups and epoxide groups, or mixtures thereof, to enhance the reactivity of the reactive groups. In the case of difunctional and polyfunctional compounds having epoxide groups, fatty acid salts, and more preferably calcium stearate and zinc stearate, may be used. In particularly preferred embodiments of the present invention, the crosslinking agent and / or chain extender comprises a compound having an epoxide group, and preferably a styrene-glycidylmethyl methacrylate type compound.

[0044] The present invention relates to a biodegradable multilayer packaging film comprising a biodegradable polyester, a polyhydroxyalkanoate in the (inner) layer B, and optionally an anti-fogging agent in the (outer) layer A. Preferably, layer B constitutes 10 to 50%, more preferably 20 to 40%, of the multilayer film. The ratio of layer A to layer B can be determined, for example, by a scanning electron microscope (SEM), as is well known to those skilled in the art. The aforementioned film possesses properties suitable for numerous practical applications related to household and industrial consumption. An example of such application is food packaging.

[0045] The film can also be advantageously manufactured by a blow molding process that allows for the recovery of a single strip-shaped film reel downstream of the film formation process by opening bubbles. This feature is particularly advantageous in terms of the productivity of the manufacturing process. The bubble blow film formation process is preferably characterized by a blow-up ratio (BUR, i.e., transverse stretching) of 2 to 5 and a draw-down ratio (DDR, i.e., longitudinal stretching) of 5 to 60 in the machine direction (MD). For the purposes of the present invention, DDR means the degree of stretching in the stretching direction when the molten material is discharged from the extruder, and BUR means the ratio of the bubble diameter to the die diameter. Advantageously, the process parameters are set such that the DDR / BUR ratio during the bubble blow process is 3 to 15.

[0046] Process aids may be added during the film formation process without affecting the adhesion or transparency of the wrap according to the present invention. Such additions are carried out according to methods known to those skilled in the art. The process aids are preferably fatty acid amides, such as stearamide, behenamide, erucamide, oleamide, ethylenebisstearamide, ethylenebisoleamide and their derivatives, and antiblocking agents, such as silica, calcium carbonate, talc, or kaolin. Fatty acid amides can be added to layer B of the multilayer film according to the present invention.

[0047] The multilayer film according to the present invention is very thin, about 3 to 50 μm thick. Preferably, it is 6 to 14 μm thick, and more preferably 8 to 10 μm thick. The multilayer film according to the present invention has high self-adhesion and also exhibits high adhesion to other non-adhesive surfaces, such as ceramics, glass, metals, and plastic materials such as HDPE, LDPE, PP, PET, and PVC. Furthermore, due to the physicochemical properties of the biodegradable polyester used, a multilayer wrap having layer A containing component i. can be manufactured without the use of plasticizers or tackifiers such as polyisobutene or ethylene vinyl acetate. This clearly demonstrates an even more significant difference between the film according to the present invention and PVC and polyethylene wraps, which have significant limitations in their use in the food packaging field due to the presence of the aforementioned additives. In a particularly preferred embodiment, the multilayer film according to the present invention maintains optimal adhesion despite substantially containing no plasticizers or tackifiers.

[0048] Multilayer films also possess excellent mechanical properties that make them particularly suitable for food packaging applications, due to a specific combination of ease of cutting, strength, and elongation. Preferably, such a multilayer film has a breaking elongation of 500% to 1000%, an elastic modulus of 80 MPa to 250 MPa, and a breaking load of 30 MPa to 50 MPa in the transverse direction with respect to the film formation direction, and a breaking elongation of 200% to 400%, an elastic modulus of 200 MPa to 400 MPa, and a breaking load of 30 MPa to 50 MPa in the longitudinal direction with respect to the film formation direction. More preferably, the multilayer film has a breaking elongation of 600% to 800%, an elastic modulus of 100 MPa to 200 MPa, and a breaking load of 30 MPa to 48 MPa in the direction transverse to the film formation direction, and a breaking elongation of 230% to 380%, an elastic modulus of 220 MPa to 400 MPa, and a breaking load of 32 MPa to 45 MPa in the direction longitudinal to the film formation direction. The multilayer film has an elastic modulus to elongation at break ratio of 0.5 to 2.0, more preferably 0.6 to 1.7, in the direction longitudinal to the film formation direction.

[0049] The mechanical properties are determined within the scope of the present invention according to ASTM D882 (tensile strength at 23°C, 55% relative humidity, and v0 = 50 mm / min). The advantage of the multilayer film according to the present invention is that it has an optimal combination of properties among ease of cutting, adhesion, and transparency. Regarding ease of cutting, the multilayer film according to the present invention exhibits low tear strength in the transverse direction (TD) and simultaneously higher tear strength in the mechanical direction (MD) than in the transverse direction (TD). Remarkably, a multilayer film is obtained characterized by a tear resistance of 10 N / mm to 60 N / mm, more preferably 20 N / mm to 50 N / mm, in the TD direction, and less than 100 N / mm in the MD direction, both of which are higher than the values ​​measured in the TD direction. This means that the multilayer film can be cut very easily without any deviation upon rupture. As a result, the product can be used optimally for household purposes. Tear resistance is measured according to ASTM standard D1922 (23°C, 55% relative humidity). Regarding adhesion, as mentioned above, the multilayer film according to the present invention exhibits optimal adhesion even when it does not contain plasticizers or tackifiers.

[0050] At the same time, the above solution is advantageously characterized by excellent optical properties, even in the presence of an anti-fogging agent. In particular, the multilayer film has a haze value of less than 20%, preferably less than 15%, and more preferably less than 10%, a clarity value of more than 80%, preferably more than 85%, and more preferably more than 90%, and a transmittance of more than 80%, preferably more than 90%. This allows users to easily identify objects packaged with the film without removing the film. This property is extremely advantageous in food packaging applications. Optical properties are measured according to ASTM standard D1003.

[0051] The biodegradable packaging film according to the present invention means a film that is biodegradable and compostable in accordance with EN13432. Unless otherwise defined, all terms, notations, and other scientific terms used herein in the art have the meanings generally understood by those skilled in the art. In some cases, terms having a generally understood meaning may be defined herein for clarity and / or convenience of reference; however, the inclusion of such definitions herein should not be construed as indicating a substantially different meaning from that generally understood in the art. The terms “include,” “possess,” and “contain” should be understood as non-restrictive terms (i.e., “include, but not limited to”), and should be understood as less restrictive than terms such as “essentially consist of” or “consist of.” The term "essentially derived from" should be understood as a semi-closed term meaning that no other components affecting the novel features of the present invention are included, and therefore, the inclusion of any excipients is permissible. The term "consisting of" should be understood as a closed term.

[0052] While various alternative modifications are possible with respect to the present invention, certain preferred embodiments will be described in detail below. However, the present invention is not intended to be limited to the specific embodiments described herein, and is intended to encompass all modifications, alternative forms, and equivalents that fall within the technical scope of the present invention as defined by the claims. The terms "for example," "e.g.," and "or" indicate non-exclusive and non-restrictive choices unless otherwise specified. The term "including" is used to mean "including, but not limited to," unless otherwise specified. [Examples]

[0053] analysis The molecular weights Mn and Mw were measured by gel permeation chromatography (GPC). The measurements were performed using a chromatography system maintained at 40°C, with two columns (with mixed porous particles of 5 μm and 3 μm) connected in series, a refractive index detector, chloroform (flow rate 0.5 ml / min) as the eluent, and polystyrene as the standard substance. The weight percentage ("q") of polyester oligomers with a GPC molecular weight of 10,000 or less was measured according to the method described herein. The melt strength was measured according to ISO 16790:2005, under conditions of 180°C, γ=103.7sl, using a capillary with a diameter of 1 mm and an L / D ratio of 30, at a constant acceleration of 6 mm / sec² and an elongation length of 110 mm. The shear viscosity of polylactic acid was measured according to ASTM standard D3835, at T=190°C, shear strain rate=141.6s⁻¹, D=1mm, and L / D=10, using dry material containing less than 400 ppm of water. The melting temperature was measured according to the method described herein. The melting rate (MFR) was measured at 190°C and 2.16 kg according to ISO 1133-1 "Plastics - Determination of melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastic plastics - Part 1: Standard test methods". Tear resistance was measured according to ASTM D1922 (23°C, 55% relative humidity). The mechanical properties of the film were measured according to ASTM standard D882 (23°C, 55% relative humidity, v0 = 50 mm / min).

[0054] material Component i. (PBAT-1): Poly(1,4-butylene adipate-co-1,4-butylene terephthalate) having a terephthalic acid content of 47 mol% relative to the total dicarboxylic acid components. The PBAT is characterized by a melt strength of 0.008 N, a number average molecular weight (Mn) of 65768, a weight average molecular weight (Mw) of 125757, an Mw / q value of 43364, and a terminal acid group content of 39 meq / kg. Ingredient ii. (A1, anti-fogging agent): Polyglycerol laurate anti-fogging agent manufactured by Sabo. Component iii. (PBAT-2): Poly(1,4-butylene adipate-co-1,4-butylene terephthalate) having a terephthalic acid content of 47 mol% relative to the total dicarboxylic acid components. This PBAT is characterized by a melt strength of 0.012 N, a number-average molecular weight (Mn) of 98605, a weight-average molecular weight (Mw) of 166380, and a terminal acid group content of 45 meq / kg. Component iv.-1 (PLA-1): Polylactic acid characterized by a shear viscosity of 204 Pa.s and a melting temperature of 153.0°C. Component iv.-2 (PLA-2): Polylactic acid characterized by a shear viscosity of 1252 Pa.s and a melting temperature of 149.1°C. Component iv.-3 (PLA-3): Polylactic acid characterized by a shear viscosity of 1239 Pa.s and a melting temperature of 152.1°C. Component v.-1 (J1, epoxy group-containing polyfunctional compound): A styrene-alkyl acrylate-glycidyl methacrylate random copolymer having Mw 6800 and epoxy equivalent (EEW) 285 g / mol, manufactured by BASF, Joncryl ADR4368. Carbodiimide additive (J2): HMV-5CA-LC, manufactured by Nisshinbo Chemical Co., Ltd. Process aid (S1): Croda SR Bead stearamide. A masterbatch containing 10% M1:J1 and 90% PLA-3 by weight. A masterbatch containing 10% by weight of M2:S1 and 90% by weight of PBAT-2.

[0055] Layer A Preparation of composition A1: "PBAT-1" was supplied at a rate of 39.32 kg / hour, "A1" at 0.6 kg / hour, and "J2" at 0.08 kg / hour to an OMC EBV60 / 36 twin-screw extruder operating under the following conditions: Screw diameter (D) = 58 mm; L / D = 36; Screw rotation speed = 140 rpm; Temperature profile = 60-150-180-190 × 4-150 × 2℃; Throughput: 40 kg / hour; Vacuum degassing was performed in Zone 8 out of a total of 10 zones. The resulting granules exhibited an MFR of 7.6 g / 10 min (according to ISO standard 1133-1, at 190°C, 2.16 kg).

[0056] Layer B [Table 1]

[0057] Each of the compositions shown in Table 1 was supplied to an OMC EBV60 / 36 twin-screw extruder operating under the following conditions: Screw diameter (D) = 58 mm; L / D = 36; Screw rotation speed = 140 rpm; Temperature profile = 60-150-180-210 × 4-150 × 2℃; Throughput: 40 kg / hour; Vacuum degassing was performed in Zone 8 out of a total of 10 zones. Table 2 shows the MFR (Metal Food Rating) of the obtained granules (according to ISO standard 1133, at 160°C and 5 kg). [Table 2]

[0058] Example: A three-layer film having an A / B / A arrangement Composition A and compositions B1, B2, and B3 (Table 1) were simultaneously supplied to a co-extruder to form a three-layer blown film having an A / B / A arrangement (Table 3). For this purpose, the compositions were supplied to a first extruder operating under the operating conditions described in Table 4, with a screw diameter of 35 mm, an L / D ratio of 30, and a temperature profile of 60-135-145×3; a second extruder operating with a screw diameter of 40 mm, an L / D ratio of 30, and a temperature profile of 60-135-170×3; and a third extruder operating with a screw diameter of 35 mm, an L / D ratio of 30, and a temperature profile of 60-135-145×3. In Example 6, the temperature profile of the 40 mm screw diameter extruder with an L / D ratio of 30 was set to 60-135-145×3. After melting, each composition was combined in a co-extrusion blow molding head set to an air gap of 0.9 mm, an L / D ratio of 9, and 150°C. Next, the mechanical properties (Table 5) and optical properties (Table 6) of the obtained films were evaluated. [Table 3]

[0059] [Table 4]

[0060] [Table 5]

[0061] [Table 6] Note to Table 6: In this invention, "adhesion" refers to the ability of the film to adhere to itself and other surfaces, evaluated on a scale from 1 (low) to 5 (high).

Claims

1. A multilayer packaging film comprising at least one layer A and one layer B, having an A / B / A arrangement of the layers, wherein layer A is: i. A biodegradable aliphatic aromatic polyester in an amount of 95 to 100% by weight relative to the total of components i to ii, having a melt strength of 0.007 N to 0.04 N: -Mn≧40000 -Mw / q≦90000 Here, Mn and Mw are the number-average molecular weight and weight-average molecular weight, respectively, and "q" is the weight percentage of polyester oligomers having a GPC molecular weight of 10,000 or less. The melt strength was determined according to ISO 16790:2005, using a capillary with 180°C, γ = 103.7 s⁻¹, diameter 1 mm, and L / D = 30, at a constant acceleration of 6 mm / sec. ２ The biodegradable aliphatic aromatic polyester was measured at an elongated length of 110 mm, and "Mn" and "Mw" were measured by gel permeation chromatography (GPC). ii. An antifogging agent in an amount of 0 to 5% by weight relative to the total of components i to iii, wherein the antifogging agent is selected from an ester of a polyfunctional alcohol, preferably a condensation product of a polyfunctional alcohol and a fatty acid, provided that the ester is not a stearate, and the antifogging agent, Including layer B: iii. At least one polyester in an amount of 60 to 90% by weight relative to the total of components iii to v.: a. For all dicarboxylic acid components, a1) 30 to 60 mol% of at least one aromatic dicarboxylic acid-derived unit, a2) 70 to 40 mol% of at least one saturated aliphatic dicarboxylic acid-derived unit, (a3) Molar units derived from at least one unsaturated aliphatic dicarboxylic acid, Dicarboxylic acid components including; b. For all diol components, b1) 95-100 mol% of at least one saturated aliphatic diol-derived unit, b2) Units derived from at least one unsaturated aliphatic diol in 0-5 mol%, Diol components containing, Polyester containing, iv. One or more polyhydroxyalkanoates in an amount of 10 to 40% by weight relative to the sum of components iii to v.; v. At least one crosslinking agent and / or chain extender in an amount of 0 to 1% by weight relative to the total of components iii. to v. Includes, A multilayer packaging film further characterized in that the content of component iv. in the multilayer film is 1.6 to 11% by weight relative to components i. to v.

2. A multilayer packaging film according to claim 1 for producing a thin film having a thickness of 3 to 50 μm, preferably 6 to 14 μm, and more preferably 8 to 10 μm.

3. The multilayer packaging film according to claim 1, wherein the anti-fogging layer A is in an amount of 0.2 to 5%, preferably 1 to 3%, relative to the total of components i to ii.

4. The multilayer packaging film according to claim 3, wherein the anti-fogging layer A is selected from fatty acid esters having 8 to 18 carbon atoms.

5. The multilayer packaging film according to claim 3, wherein the anti-fogging layer A is selected from polyglyceryl laurate and sorbitan monolaurate.

6. The multilayer packaging film according to claim 1, wherein layer A does not contain one or more polyhydroxyalkanoates.

7. The multilayer packaging film according to claim 1, wherein in layer B, component iii. varies between 71 and 85% by weight, more preferably between 75 and 81% by weight, relative to the total of components iii. to v.

8. The multilayer packaging film according to claim 1, wherein in layer B, component iv. varies between 15 and 29% by weight of the total of components iii to v., more preferably between 19 and 25% by weight of the total of components iii to v.

9. The multilayer packaging film according to claim 1, wherein in layer B, component iv. is one or more lactic acid polyesters.

10. The multilayer packaging film according to claim 9, wherein the lactic acid polyester (component iv) of layer B has a melting temperature (Tm) of 135 to 160°C and a glass transition temperature (Tg) of 45 to 75°C.

11. The multilayer packaging film according to claim 1, wherein the aromatic dicarboxylic acid in component a1) of layer B is preferably selected from phthalic acid-type aromatic dicarboxylic acids, preferably terephthalic acid or isophthalic acid, more preferably terephthalic acid, their esters, salts, and mixtures.

12. The multilayer packaging film according to claim 1, wherein the saturated aliphatic dicarboxylic acid in component a2) of layer B is preferably selected from saturated C2-C24, preferably C4-C13, more preferably C4-C11 dicarboxylic acids, C1-C24, preferably C1-C4 alkyl esters thereof, salts thereof, and mixtures thereof.

13. The multilayer packaging film according to claim 12, wherein the saturated aliphatic dicarboxylic acid in component a2) is selected from succinic acid, 2-ethylsuccinic acid, glutaric acid, 2-methylglutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanediic acid, dodecanediic acid, brassic acid and their C1-C24 alkyl esters.

14. The multilayer packaging film according to claim 1, wherein the crosslinking agent and / or chain extender (component v.) in layer B is selected from difunctional and polyfunctional compounds having epoxide groups.

15. A multilayer packaging film according to claims 1 to 14, for household use.

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