RU2795428C2 - Multilayer biodegradable film - Google Patents

Abstract

FIELD: multilayer biodegradable film.

SUBSTANCE: invention can be used in manufacturing of packaging and has a noticeable optical transparency along with high level mechanical characteristics. The multilayer film contains at least one first layer A and at least one second layer B, and layers A and B have an A/B/A mutual arrangement, layer A and layer B differ from each other, layer A contains aliphatic and/or aliphatic-aromatic biodegradable polyester, whereas layer B contains from 30 to 95% by weight of at least one polyester, from 0.1 to 40% by weight of starch, from 1 to 30% by weight of at least one lactic acid polyester, from 0 to 15% by weight of at least one inorganic filler and from 0 to 5% by weight of at least one cross-linking agent and/or chain extender, and the specified aliphatic-aromatic polyester in layer A contains a dicarboxylic component; and a diol component.

EFFECT: multilayer film according to the invention has very good mechanical properties, high biodegradability and good optical properties, which makes it suitable for manufacturing of various types of packaging and can also be used for manufacturing of mulch films due to its high degree of degradability at low temperatures, combined with good mechanical properties.

18 cl, 1 tbl, 7 ex

Description

This invention relates to a multilayer biodegradable film that can be used in the manufacture of various types of packaging, in particular bags for carrying products and bags for packaging foodstuffs, such as bags for fruits and vegetables. In addition to high-level mechanical properties, in particular a high modulus of elasticity, these films exhibit noticeable optical transparency.

The production of packaging, in particular food packaging bags such as bags for fruits and vegetables, requires the use of films that combine good mechanical properties with other properties desired by the consumer, such as, in particular, optical transparency characteristics that allow consumers to use packaging, identifying the object contained inside from the outside.

In the biodegradable packaging industry, along with mechanical and optical challenges, there is also a need to use materials that can degrade after they have reached the end of their primary use, without leading to the accumulation of waste in the environment. The development of biodegradable films that combine these different properties is, in fact, a complex task, requiring a balance of different needs, often conflicting with each other. In fact, although certain standards regarding mechanical properties and biodegradability (biodegradability) can be achieved through the use of material compositions that share each of the final properties of the film according to their different characteristics, it is the heterogeneous nature that very often prevents the achievement of high optical transparency. the specified compositions. For manufacturers of biodegradable packaging films, this means that they must decide whether to use a film that has high mechanical properties and good biodegradability, but with suboptimal optical clarity characteristics, or, conversely, to use aspects related to the optical characteristics of the packaging, thereby agreeing on not so high mechanical properties and biodegradability.

Thus, if it were possible to develop a film capable of balancing these opposing requirements, i.e. a film with a high level of biodegradability and mechanical properties, in particular a high modulus of elasticity, and with significant optical transparency characteristics, this would overcome the existing problems described higher.

The present invention addresses this problem and provides a solution to properly balance these differing requirements. In particular, this invention relates to a multilayer film containing at least one first layer A and at least one second layer B, where layer A and layer B differ from each other, in which layer A contains a biodegradable aliphatic and/or aliphatic - aromatic polyester or polyvinyl alcohol or their copolymers, and in which layer B contains:

i) from 30 to 95 wt. %, preferably from 50 to 85%, relative to the sum of components i to v, of at least one polyester comprising:

a) a dicarboxylic component, comprising, relative to the total amount of the dicarboxylic component:

a1) 35 to 70 mol%, preferably 40 to 60 mol%, more preferably 45 to 60 mol%, of units derived from at least one aromatic dicarboxylic acid;

a2) 65 to 30 mole %, preferably 60 to 40 mole %, more preferably 55 to 40 mole %, of units derived from at least one saturated aliphatic dicarboxylic acid;

a3) from 0 to 5 mol.% units derived from at least one unsaturated aliphatic dicarboxylic acid;

b) a diol component comprising, relative to the total amount of the diol component:

b1) from 95 to 100 mol.% units derived from at least one saturated aliphatic diol;

b2) 0 to 5 mole % of units derived from at least one unsaturated aliphatic diol;

ii) from 0.1 to 50 wt. %, preferably from 5 to 40 wt. %, relative to the sum of components i to v, of at least one polymer of natural origin;

iii) from 1 to 40 wt. %, preferably from 2 to 30 wt. %, relative to the sum of components i to v, at least one polyhydroxyalkanoate;

iv) 0 to 15 wt. %, relative to the sum of components i to v, at least one inorganic filler;

v) 0 to 5 wt. %, preferably from 0 to 0.5 wt. %, relative to the sum of components from i to v, at least one cross-linking agent and / or chain extender, including at least one compound having two or more functional groups, including isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxy, anhydride or divinyl ether groups and mixtures thereof.

One of the features of the multilayer film according to the present invention is that its layered structure includes at least one layer containing aliphatic-aromatic and/or aliphatic biodegradable polyester or polyvinyl alcohol or their copolymers (layer A), and at least one layer containing a polymer composition comprising components i to v (layer B). Surprisingly, it has been found that a multilayer film having such a combination of materials has very good mechanical properties, high biodegradability and good optical properties, making it suitable for various types of packaging.

In particular, layer B of the multilayer film according to the present invention contains a continuous phase and a discontinuous phase in its structure capable of making the film rapidly biodegradable under industrial composting conditions, and more preferably home composting in accordance with the UNI11355 standard. Said film also has high mechanical properties and is very thin; for example, being in the form of pouches not more than 50 cm high, not more than 40 cm wide (with or without folds) and pouches with handles having a handle width of 5 to 3 cm and a thickness of not more than 15 µm and more preferably less than 12 µm, the bags can support a weight of at least 3 kg and even more preferably at least 4 kg under shake test conditions. As an example of one possible type of manual shaking, consider lifting a 40 cm bag off the ground 10 times in a row without any breaks. Despite the fact that the structure of the individual layer B has optical characteristics that are significantly inferior to the optical characteristics of non-biodegradable materials commonly used for packaging, such as, for example, HDPE (English high-density polyethylene - high-density polyethylene), a multilayer film according to this invention has optical characteristics similar to those of HDPE due to its structure providing a combination of at least one layer A and at least one layer B, while maintaining the biodegradability characteristics of layer B (industrial composting and more preferably compostability and/or dispersibility at home in mechanical mixing processes prior to anaerobiosis treatments). In particular, the multilayer film has optical transmission values above 90%, preferably above 91%, haze below 65%, preferably below 55%, and transparency above 20%, preferably above 40%.

The present invention also relates to various types of packaging, in particular to bags for carrying products and bags for food packaging, such as bags for products and vegetables, including the specified multilayer film.

The multilayer film according to this invention contains at least one layer A and at least one layer B, preferably characterized by a mutual arrangement selected from A/B and A/B/A.

LAYER A

Layer A contains at least one aliphatic and/or aliphatic-aromatic polyester or polyvinyl alcohol or their copolymers. As for the aliphatic-aromatic polyester, it preferably contains:

c) a dicarboxylic component, comprising, relative to the total amount of the dicarboxylic component:

c1) 35 to 70 mol%, preferably 40 to 60 mol%, more preferably 45 to 60 mol%, of units derived from at least one aromatic dicarboxylic acid;

c2) 65 to 30 mol%, preferably 60 to 40 mol%, more preferably 55 to 40 mol%, of units derived from at least one saturated aliphatic dicarboxylic acid;

c3) from 0 to 5 mole % of units derived from at least one unsaturated aliphatic dicarboxylic acid;

d) a diol component comprising, relative to the total amount of the diol component:

d1) from 95 to 100 mole % of units derived from at least one saturated aliphatic diol;

d2) 0 to 5 mole % units derived from at least one unsaturated aliphatic diol.

The aromatic dicarboxylic acids in component c1 are preferably selected from aromatic dicarboxylic acids of the phthalic acid type, preferably terephthalic acid or isophthalic acid, more preferably terephthalic acid, and heterocyclic dicarboxylic aromatic compounds, preferably 2,5-furandicarboxylic acid, 2,4-furandicarboxylic acid acids, 2,3-furandicarboxylic acid, 3,4-furandicarboxylic acid, more preferably 2,5-furandicarboxylic acid, esters, salts and mixtures thereof. According to one preferred embodiment, said aromatic dicarboxylic acids include:

- from 1 to 99 mol.%, preferably from 5 to 95% and more preferably from 10 to 80% of terephthalic acid, its esters or salts;

- from 99 to 1 mol.%, preferably from 95 to 5% and more preferably from 90 to 20% of 2,5-furandicarboxylic acid, its esters or salts.

The saturated aliphatic dicarboxylic acids in component c2 are preferably selected from saturated C ₂ -C ₂₄ , preferably C ₄ -C ₁₃ , more preferably C ₄ -C ₁₁ dicarboxylic acids, their C ₁ -C ₂₄ , preferably C ₁ -C ₄ , alkyl esters, their salts and mixtures thereof. Preferably, the saturated aliphatic dicarboxylic acids are selected from succinic acid, 2-ethylsuccinic acid, glutaric acid, 2-methylglutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassilic acid, hexadecanedicarboxylic acid , octadecane dicarboxylic acid and their C _1-24 alkyl esters. According to one of the preferred embodiments of this invention, the saturated aliphatic dicarboxylic acid includes mixtures containing at least 50 mol.%, preferably more than 60 mol.%, more preferably more than 65 mol.% succinic acid, adipic acid, azelaic acid, sebacic acid, brassilic acid, their C ₁ -C ₂₄ , preferably C _{1 -} C ₄ , esters and mixtures thereof. According to a particularly preferred embodiment, said mixtures comprise or consist of adipic acid and azelaic acid and contain azelaic acid in an amount of from 5 to 40 mol%, more preferably from 10 to 35 mol% of azelaic acid, relative to the sum of adipic acid and azelaic acid. acids.

The unsaturated aliphatic dicarboxylic acids in component c3 are preferably selected from itaconic acid, fumaric acid, 4-methylene pimelic acid, 3,4-bis(methylene)nonanedicarboxylic acid, 5-methylenenonanedicarboxylic acid, their C ₁ -C ₂₄ , preferably C ₁ -C ₄ , alkyl esters, their salts and mixtures thereof. According to one of the preferred embodiments of this invention, unsaturated aliphatic dicarboxylic acids include mixtures containing at least 50 mol.%, preferably more than 60 mol.%, more preferably more than 65 mol.% of itaconic acid and its C ₁ -C ₂₄ , preferably C ₁ -C ₄ esters. More preferably, the unsaturated aliphatic dicarboxylic acids consist of itaconic acid.

The saturated aliphatic diols in component d1 are preferably selected from 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, dianhydromannite, dianhydroidite, cyclohexanediol, cyclohexanemethanediol, dialkylene glycols and polyalkylene glycols having a molecular weight of from 100 to 4000, such as, for example, polyethylene glycol, polypropylene glycol and mixtures thereof. Preferably, the diol component contains at least 50 mole % of one or more diols selected from 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol. More preferably, the diol component contains or consists of 1,4-butanediol.

The unsaturated aliphatic diols in component 62 are preferably selected from cis-2-butene-1,4-diol, trans-2-butene-1,4-diol, 2-butyn-1,4-diol, cis-2-pentene-1 ,5-diol, trans-2-pentene-1,5-diol, 2-pentyn-1,5-diol, cis-2-hexene-1,6-diol, trans-2-hexene-1,6-diol , 2-hexine-1,6-diol, cis-3-hexene-1,6-diol, trans-3-hexene-1,6-diol, 3-hexine-1,6-diol.

As for the aliphatic polyester, it preferably contains:

e) a dicarboxylic component, comprising, relative to the total amount of the dicarboxylic component:

e1) from 95 to 100 mol.% units derived from at least one aliphatic dicarboxylic acid;

e2) from 0 to 5 mol.% units derived from at least one unsaturated aliphatic dicarboxylic acid;

f) a diol component comprising, relative to the total amount of the diol component:

f1) from 95 to 100 mol.% units derived from at least one saturated aliphatic diol;

f2) 0 to 5 mole % of units derived from at least one unsaturated aliphatic diol.

The saturated aliphatic dicarboxylic acids in component e1 are preferably selected from saturated C ₂ -C ₂₄ , preferably C ₄ -C ₁₃ , more preferably C ₄ -C ₁₁ dicarboxylic acids, their C ₁ -C ₂₄ , preferably C ₁ -C ₄ alkyl esters, their salts and mixtures thereof. Preferably, the saturated aliphatic dicarboxylic acids are selected from succinic acid, 2-ethylsuccinic acid, glutaric acid, 2-methylglutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassilic acid, hexadecanedicarboxylic acid , octadecane dicarboxylic acid and their C ₁ - ₂₄ alkyl esters.

The unsaturated aliphatic dicarboxylic acids in component e2 are preferably selected from itaconic acid, fumaric acid, 4-methylene pimelic acid, 3,4-bis(methylene)nonanedicarboxylic acid, 5-methylenenonanedicarboxylic acid, their C ₁ -C ₂₄ , preferably C ₁ -C ₄ alkyl esters, their salts and mixtures thereof. According to one of the preferred embodiments of this invention, unsaturated aliphatic dicarboxylic acids include mixtures containing at least 50 mol.%, preferably more than 60 mol.%, more preferably more than 65 mol.%, itaconic acid and its C ₁ -C ₂₄ , preferably C ₁ -C ₄ esters. More preferably, the unsaturated aliphatic dicarboxylic acids consist of itaconic acid.

The saturated aliphatic diols in component f1 are preferably selected from 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, dianhydromannite, dianhydroidite, cyclohexanediol, cyclohexanemethanediol, dialkylene glycols and polyalkylene glycols having a molecular weight of from 100 to 4000, such as, for example, polyethylene glycol, polypropylene glycol and mixtures thereof. Preferably, the diol component contains at least 50 mole % of one or more diols selected from 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol. More preferably, the diol component contains or consists of 1,4-butanediol.

The unsaturated aliphatic diols in component f2 are preferably selected from cis-2-butene-1,4-diol, trans-2-butene-1,4-diol, 2-butyn-1,4-diol, cis-2-pentene-1 ,5-diol, trans-2-pentene-1,5-diol, 2-pentyn-1,5-diol, cis-2-hexene-1,6-diol, trans-2-hexene-1,6-diol , 2-hexine-1,6-diol, cis-3-hexene-1,6-diol, trans-3-hexene-1,6-diol, 3-hexine-1,6-diol.

The molecular weight Mn of said aliphatic and/or aliphatic-aromatic polyester in layer A is preferably ≧20,000, more preferably ≧40,000. Alternatively, the molecular weight polydispersity ratio, Mw/Mn, is preferably 1.5 to 10, more preferably 1.6 to 5, and even more preferably 1.8 to 2.7.

The molecular weights of Mn and _Mw can be measured using Gel Permeation Chromatography (GPC). The determination can be performed with a chromatographic system maintained at 40°C using a set of two columns in series (particle diameters 5 µm and 3 µm with mixed porosity), a refractive index detector, chloroform as eluent (flow rate 0.5 ml/min) and polystyrene as reference.

The acid end content of said aliphatic and/or aliphatic-aromatic polyester in layer A is preferably less than 100 meq/kg, preferably less than 60 meq/kg and even more preferably less than 40 meq/kg.

The content of terminal acid groups can be measured as follows: 1.5-3 g of polyester are placed in a 100 ml flask together with 60 ml of chloroform. After complete dissolution of the polyester, 25 ml of propanol-2 and then 1 ml of deionized water are added immediately before analysis. The solution thus obtained is titrated with a previously standardized solution of NaOH in ethanol. To determine the end point of the titration, an appropriate indicator is used, such as, for example, a glass electrode for acid-base titration in non-aqueous solvents. The content of acid end groups is calculated based on the consumption of NaOH solution in ethanol using the following equation:

Where

V _eq = volume in ml of NaOH in ethanol at the end point of the sample titration;

V _b =volume in ml of NaOH solution in ethanol required to achieve a pH value of 9.5 in a blank titration;

T = concentration of NaOH solution in ethanol, expressed in mol/l;

P = sample weight in g.

Preferably, said aliphatic and/or aliphatic-aromatic polyester in layer A has an intrinsic viscosity greater than 0.3 dl/g (measured with an Ubbelohde viscometer for solutions of 0.2 g/dl in CHCl ₃ at 25° C.), preferably 0.3 to 2 dl/g, more preferably 0.4 to 1.1 dl/g.

Said aliphatic and/or aliphatic-aromatic polyester in layer A is biodegradable. In the context of this invention, a biodegradable polymer is understood to mean a biodegradable polymer in accordance with EN 13432.

Said aliphatic and/or aliphatic-aromatic polyester in layer A can be synthesized by any of the methods known in the art. In particular, it can be advantageously obtained by a polycondensation reaction.

Preferably, the synthesis process may be carried out in the presence of a suitable catalyst. As examples of suitable catalysts, mention may be made of organometallic tin compounds, eg stannonic acid derivatives, titanium compounds, eg orthobutyl titanate, aluminum compounds, eg triisopropylaluminum, antimony, zinc and zirconium compounds, and mixtures thereof.

According to another embodiment of the present invention, said aliphatic polyester in layer A is a hydroxy acid polyester, preferably poly-ε-caprolactone.

In layer A, said at least one aliphatic and/or aliphatic-aromatic polyester is thoroughly mixed with one or more other components. In this case, layer A contains a composition comprising at least one aliphatic and/or aliphatic-aromatic polyester or polyvinyl alcohol or copolymers thereof and preferably one or more polymers other than said aliphatic and/or aliphatic-aromatic polyester or polyvinyl alcohol or their copolymers, synthetic or natural origin, which may or may not be biodegradable, and preferably one or more other components.

Polymers other than said aliphatic and/or aliphatic-aromatic polyester or polyvinyl alcohol or their copolymers of synthetic or natural origin, whether biodegradable or not, are preferably selected from the group consisting of polyhydroxyalkanoates, vinyl polymers, complex dibasic acid polyesters and diols other than polyester i, polyamides, polyurethanes, polyethers, polyureas, polycarbonates and mixtures thereof.

With regard to non-biodegradable polymers, it seems clear that they are present in amounts that do not have a significant effect on the biodegradability of the final product.

According to one of the preferred embodiments, said composition in layer A contains, in addition to said aliphatic and/or aliphatic-aromatic polyester or polyvinyl alcohol or their copolymers, from 1 to 40 wt. % and, more preferably, from 5 to 30 wt. %, relative to the entire layer A, of at least one polyhydroxyalkanoate, more preferably selected from the group consisting of polyesters of lactic acid, poly-ε-caprolactone, polyhydroxybutyrate, polyhydroxybutyrate-valerate, polyhydroxybutyrate-propanoate, polyhydroxybutyrate-hexanoate, polyhydroxybutyrate-decanoate , polyhydroxybutyrate-dodecanoate, polyhydroxybutyrate-hexadecanoate, polyhydroxybutyrate-octadecanoate, poly-3-hydroxybutyrate-4-hydroxybutyrate. Preferably, the specified polyhydroxyalkanoate contains at least 80 wt. % of one or more lactic acid polyesters.

According to one preferred embodiment, the lactic acid polyesters are selected from the group consisting of poly-L-lactic acid, poly-D-lactic acid, poly-D-L-lactic acid stereocomplex, copolymers containing more than 50 mole % of said polyesters. lactic acid, or mixtures thereof.

Particularly preferred are polyesters of lactic acid containing at least 95 wt. % repeating units derived from L-lactic or D-lactic acid, or combinations thereof, having a molecular weight Mw greater than 50,000 and a shear viscosity of 50 to 500 Pa⋅s, preferably 100 to 300 Pa⋅s (measured according to the ASTM standard D3835 at T=190°C, shear rate=1000 s ^-1 , D=1 mm, L/D=10).

According to a particularly preferred embodiment of the invention, the polyester lactic acid contains at least 95 wt. % of units derived from L-lactic acid, ≤5% of repeating units derived from D-lactic acid, has a melting point in the range of 135 to 180°C, a glass transition temperature (Tg) in the range of 55 to 65°C and a value MFR (eng. melt mass-flow rate - mass flow rate of the melt flow) (measured in accordance with ISO 1133-1 at a temperature of 190 ° C and 2.16 kg) in the range from 1 to 50 g / 10 min. Commercially available examples of lactic acid polyesters having these properties are, for example, Ingeo™ Biopolymer 4043D, 3251D and 6202D products.

Among vinyl polymers, polyethylene, polypropylene, their copolymers, polyvinyl alcohol, polyvinyl acetate, polyethylvinyl acetate and polyethylene vinyl alcohol, polystyrene, chlorinated vinyl polymers and polyacrylates are preferred.

Chlorinated vinyl polymers that can be included in this work, in addition to polyvinyl chloride, include polyvinylidene chloride, polyethylene chloride, poly-(vinyl chloride-vinyl acetate), poly-(vinyl chloride-ethylene), poly-(vinyl chloride-propylene), poly-(vinyl chloride-styrene ), poly-(vinyl chloride-isobutylene) and copolymers in which polyvinyl chloride is more than 50 mol.%. These polymers may be random copolymers, block copolymers or alternating copolymers.

The polyamides in the composition according to this invention are preferably selected from the group consisting of polyamide 6 and 6,6, polyamide 9 and 9,9, polyamide 10 and 10,10, polyamide 11 and 11,11, polyamide 12 and 12,12, and combinations thereof. types 6/9, 6/10, 6/11 and 6/12, mixtures thereof, as well as random copolymers and block copolymers.

Preferably, the polycarbonates of the composition according to this invention are selected from the group consisting of polyalkylene carbonates, more preferably polyethylene carbonates, polypropylene carbonates, polybutylene carbonates, mixtures thereof, as well as random copolymers and block copolymers.

Among polyethers, preferred are compounds selected from the group consisting of polyethylene glycols, polypropylene glycols, polybutylene glycols, their copolymers and mixtures thereof, having molecular weights from 70,000 to 500,000.

Polyesters of diacids and diols other than said aliphatic and/or aliphatic-aromatic polyester in layer A preferably include:

g) a dicarboxylic component, comprising, relative to the total amount of the dicarboxylic component:

g1) from 20 to 100 mol.% units derived from at least one aromatic dicarboxylic acid,

g2) from 0 to 80 mole % of units derived from at least one saturated aliphatic dicarboxylic acid,

g3) 0 to 5 mole % of units derived from at least one unsaturated aliphatic dicarboxylic acid;

h) a diol component comprising, relative to the total amount of the diol component:

h1) from 95 to 100 mol.% units derived from at least one saturated aliphatic diol;

h2) 0 to 5 mole % of units derived from at least one unsaturated aliphatic diol.

Preferably, the g1 aromatic dicarboxylic acids, g2 saturated aliphatic dicarboxylic acids, g3 unsaturated aliphatic dicarboxylic acids, h1 saturated aliphatic diols and h2 unsaturated aliphatic diols for said polyesters are selected from the compounds described above for the aliphatic-aromatic polyester in layer A according to this invention .

At least one crosslinker and/or chain extender may also be present in the composition of layer A to improve resistance to hydrolysis. The crosslinker and/or chain extender is selected from compounds having two and/or more functional groups, including isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxy, anhydride or divinyl ether groups, or mixtures thereof. Preferably, the crosslinker and/or chain extender contains at least one compound having two and/or more functional groups, including isocyanate groups. More preferably, the crosslinker and/or chain extender contains at least 25 wt. % of one or more compounds having two and/or multiple functional groups, including isocyanate groups. Especially preferred are mixtures of compounds having two and/or multiple functional groups, including isocyanate groups, with compounds having two and/or multiple functional groups, including epoxy groups, even more preferably containing at least 75 wt. % compounds having two and/or multiple functional groups, including isocyanate groups.

Compounds having di- or multifunctional groups including isocyanate groups are preferably selected from p-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4-diphenylmethane diisocyanate, 1,3-phenylene-4-chlorodiisocyanate, 1 ,5-naphthalene diisocyanate, 4,4-diphenylene diisocyanate, 3,3'-dimethyl-4,4-diphenylmethane diisocyanate, 3-methyl-4,4'-diphenylmethane diisocyanate, diphenyl ether diisocyanate, 2,4-cyclohexane diisocyanate, 2,3-cyclohexane diisocyanate , 1-methyl-2,4-cyclohexyl diisocyanate, 1-methyl 2,6-cyclohexyl diisocyanate, bis-(isocyanatecyclohexyl)methane, 2,4,6-toluene triisocyanate, 2,4,4-diphenylether triisocyanate, polymethylene-polyphenyl-polyisocyanates, methylene diphenyl diisocyanate, triphenylmethane triisocyanate, 3,3'-dioluene-4,4-diisocyanate, 4,4'-methylene-bis-(2-methylphenylisocyanate), hexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,2-cyclohexylene diisocyanate and mixtures thereof. According to one preferred embodiment, the isocyanate group-containing compound is 4,4-diphenylmethane diisocyanate.

Compounds having two and/or multiple functional groups including peroxide groups are preferably selected from benzoyl peroxide, lauroyl peroxide, isononanoyl peroxide, di-(t-butylperoxyisopropyl)benzene, t-butyl peroxide, dicumyl peroxide, α,α-di -(tert-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di-(butylperoxy)hexane, tert-butylcumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-( tert-butylperoxy)hex-3-yne, di-(4-tert-butylcyclohexyl)peroxydicarbonate, dicetylperoxydicarbonate, dimyristylperoxydicarbonate, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane, di -(2-ethylhexyl)peroxydicarbonate and mixtures thereof.

Compounds having two and/or multiple functional groups comprising carbodiimide groups, preferably used in the composition according to this invention, are selected from poly-(cyclooctylenecarbodiimide), poly-(1,4-dimethylenecyclohexylenecarbodiimide), 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 ^® R), 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-phenylene- bis(ethylcarbodiimide), 1,6-hexamethylene-bis(ethylcarbodiimide), 1,8-octamethylene-bis(ethylcarbodiimide), 1,10-decamethylene-bis(ethylcarbodiimide), 1,12-dodecamethylene-bis(ethylcarbodiimide) and their mixtures.

Examples of compounds having two or more functional groups, including epoxy groups, which can be successfully used in the composition according to this invention are all polyepoxides from epoxidized oils and/or from styrene-glycidyl ether-methyl methacrylate or glycidyl ether-methyl methacrylate falling into molecular weight range from 1000 to 10000 and having an epoxy number per molecule in the range of 1 to 30 and preferably 5 to 25, epoxides are selected from the group consisting of: diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, glycerol dipolyglycidyl ether , 1,2-epoxybutane, polyglycerol polyglycidyl ether, isoprene diepoxide and cycloaliphatic diepoxides, 1,4-cyclohexanedimethanol diglycidyl ether, glycidyl-2-methylphenyl ether, glycerol propoxylate triglycidyl ether, 1,4-butanediol diglycidyl ether, sorbitol polyglycidyl ether, diglycidyl ether glycerol, meta-xylenediamine tetraglycidyl ethers and diglycidyl ether or bisphenol A, and mixtures thereof.

Catalysts can also be used with compounds having two or more functional groups, including isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxy, anhydride and divinyl ether groups, such as, for example, those described above, to increase the reactivity of the functional groups. In the case of polyepoxides, fatty acid salts, preferably calcium and zinc stearates, can preferably be used.

According to a particularly preferred embodiment of the invention, the crosslinker and/or chain extender for the composition in layer A comprises compounds containing isocyanate groups, preferably 4,4-diphenylmethane diisocyanate, and/or containing carbodiimide groups, and/or containing epoxy groups, preferably styrene-glycidyl ether-methyl methacrylate type.

In the composition of layer A, a filler may also be present in an amount of up to 10 wt. %, relative to the entire layer A.

Layer A composition of the multilayer film according to the present invention does not contain starch.

In addition to the components mentioned above, the composition in layer A preferably also contains at least one other component selected from the group consisting of plasticizers, UV stabilizers, lubricants, nucleating agents, surfactants, antistatic additives, pigments, flame retardants , compatibilizers, lignin, organic acids, antioxidants, anti-mildew agents, waxes, processing aids and polymer components, preferably selected from the group consisting of vinyl polymers, diacid polyesters and diols which are not aliphatic-aromatic polyesters as described above, polyamides, polyurethanes, polyethers, polyureas or polycarbonates.

Preferably, plasticizers are present in the composition of layer A according to this invention, where one or more plasticizers are selected from the group consisting of water, polyhydric alcohols containing from 2 to 22 carbon atoms, phthalates such as, for example, diisononyl phthalate, trimellitates, such as, for example, esters of trimellitic acid with C ₄ -C ₂₀ monoalcohols, preferably selected from the group consisting of n-octanol and n-decanol, and aliphatic esters having the following structure:

R ₁ -OC(O)-R ₄ -C(O)-[-OR ₂ -OC(O)-R ₅ -C(O)-] _m -OR ₃ ,

Where:

R ₁ is selected from one or more groups, including H, linear and branched, saturated and unsaturated alkyl residues of the C ₁ -C ₂₄ type, residues of polyhydric alcohols esterified with C ₁ -C ₂₄ monobasic carboxylic acids;

R ₂ contains -CH ₂ -C(CH ₃ ) ₂ -CH ₂ - and C ₂ -C ₈ alkylene groups, and contains at least 50 mol.% of the indicated -CH ₂ -C(CH ₃ ) ₂ -CH ₂ - groups;

R ₃ is selected from one or more groups including H, linear and branched, saturated and unsaturated alkyl residues of the C ₁ -C ₂₄ type, polyhydric alcohol residues esterified with C ₁ -C ₂₄ monobasic carboxylic acids;

R ₄ and R ₅ are the same or different, include one or more C ₂ -C ₂₂ , preferably C ₂ -C ₁₁ , more preferably C ₄ -C ₉ alkylene, and include at least 50 mole % C ₇ alkylenes .

m is a number from 1 to 20, preferably from 2 to 10, more preferably from 3 to 7.

Preferably, in said esters, at least one of the groups R ₁ and/or R ₃ contains, preferably in amounts ≥10 mol.%, more preferably ≥20%, even more preferably ≥25 mol.%, relative to the total amounts of R ₁ and/or R ₃ groups, polyhydric alcohol residues esterified with at least one C _1- C ₂₄ monobasic carboxylic acid selected from the group consisting of stearic acid, palmitic acid, 9-ketostearic acid, 10-ketostearic acid and their mixtures. Examples of aliphatic esters of this type are disclosed in Italian patent application MI2014A000030 and in international applications PCT/EP2015/050336, PCT/EP2015/050338.

If they are present in layer A, the selected plasticizers are preferably present in an amount of up to 10 wt. % relative to the total weight of the layer A composition as such.

Lubricants are preferably selected from fatty acid esters and metal salts such as, for example, zinc stearate, calcium stearate, aluminum stearate and acetyl stearate. Preferably, the layer composition A according to this invention contains up to 1 wt. % lubricants, more preferably up to 0.5 wt. %, relative to the total weight of the layer A composition.

Examples of nucleating agents include sodium saccharin, calcium silicate, sodium benzoate, calcium titanate, boron nitride, isotactic polypropylene or low molecular weight PLA (polylactide-polylactide). Such additives are preferably introduced in amounts up to 10 wt. % and, more preferably, from 2 to 6 wt. %, relative to the total weight of the composition.

If desired, pigments may also be added, for example titanium dioxide, clays, copper phthalocyanine, titanium dioxide, silicates, iron oxide and hydroxides, carbon black and magnesium oxide. Such additives are preferably introduced in amounts up to 10 wt. %.

According to one preferred embodiment, layer A of the multilayer film according to the invention comprises, relative to the sum of components i to v:

i) from 30 to 70 wt. % of at least one aliphatic-aromatic polyester;

ii) from 20 to 60 wt. % of at least one aliphatic polyester;

iii) from 1 to 20 wt. % of at least one polyhydroxyalkanoate;

iv) 0 to 5 wt. %, preferably from 0 to 0.5%, at least one crosslinker and/or chain extender containing at least one compound having two and/or multiple functional groups, including isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline , epoxy, anhydride or divinyl ether groups and mixtures thereof;

v) from 0 to 10 wt. %, preferably from 0 to 5%, of at least one filler.

According to one preferred embodiment, layer A of the multilayer film according to the invention comprises, relative to the sum of components i to v:

i) from 60 to 100 wt. % of at least one aliphatic-aromatic polyester;

ii) from 0 to 20 wt. % of at least one aliphatic polyester;

iii) from 0 to 40 wt. % of at least one polyhydroxyalkanoate;

iv) 0 to 5 wt. %, preferably from 0 to 0.5%, at least one crosslinker and/or chain extender containing at least one compound having two and/or multiple functional groups, including isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline , epoxy, anhydride or divinyl ether groups and mixtures thereof;

v) from 0 to 10 wt. %, preferably from 0 to 5%, of at least one filler.

According to one preferred embodiment, layer A of the multilayer film according to the invention comprises, relative to the sum of components i to v:

i) from 0 to 20 wt. % of at least one aliphatic-aromatic polyester;

ii) from 60 to 100 wt. % of at least one aliphatic polyester;

iii) from 0 to 40 wt. % of at least one polyhydroxyalkanoate;

iv) 0 to 5 wt. %, preferably from 0 to 0.5%, at least one crosslinker and/or chain extender containing at least one compound having two and/or multiple functional groups, including isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline , epoxy, anhydride or divinyl ether groups and mixtures thereof;

v) from 0 to 10 wt. %, preferably from 0 to 5%, of at least one filler.

LAYER B

Layer B contains:

i) from 30 to 95 wt. %, preferably from 50 to 85 wt. %, relative to the sum of components from i to v, at least one polyester, including:

a) a dicarboxylic component, including, relative to the entire dicarboxylic component:

a1) 35 to 70 mol%, preferably 40 to 60 mol%, more preferably 45 to 60 mol%, of units derived from at least one aromatic dicarboxylic acid;

a2) 70 to 35 mole %, preferably 60 to 40 mole %, more preferably 55 to 40 mole %, of units derived from at least one saturated aliphatic dicarboxylic acid;

a3) from 0 to 5 mol.% units derived from at least one unsaturated aliphatic dicarboxylic acid;

b) a diol component comprising, relative to the total diol component:

b1) from 95 to 100 mol.% units derived from at least one saturated aliphatic diol;

b2) 0 to 5 mole % of units derived from at least one unsaturated aliphatic diol;

ii) from 0.1 to 50 wt. %, preferably from 5 to 40 wt. %, relative to the sum of components from i to v, at least one polymer of natural origin,

iii) from 1 to 40 wt. %, preferably from 2 to 30 wt. %, relative to the sum of components i to v, at least one polyhydroxyalkanoate;

iv) 0 to 15 wt. %, relative to the sum of components i to v, at least one inorganic filler;

v) 0 to 5 wt. %, preferably from 0 to 0.5 wt. %, relative to the sum of components from i to v, at least one crosslinking agent and/or chain extender, including at least one compound having two and/or multiple functional groups, including isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxy , anhydride or divinyl ether groups and mixtures thereof.

The aromatic dicarboxylic acids in the polyester component a1 are preferably selected from aromatic dicarboxylic acids of the phthalic acid type, preferably terephthalic acid or isophthalic acid, more preferably terephthalic acid, and heterocyclic aromatic dicarboxylic acids, preferably 2,5-furandicarboxylic acid, 2,4 -furandicarboxylic acid, 2,3-furandicarboxylic acid, 3,4-furandicarboxylic acid, more preferably 2,5-furandicarboxylic acid, their esters, salts and mixtures. According to one of the preferred embodiments, aromatic dicarboxylic acids include:

- from 1 to 99 mol.%, preferably from 5 to 95% and more preferably from 10 to 80%, terephthalic acid, its esters or salts;

- from 99 to 1 mol.%, preferably from 95 to 5% and more preferably from 90 to 20%, 2,5-furandicarboxylic acid, its esters or salts.

The saturated aliphatic dicarboxylic acids in the a2 component of polyester i are preferably selected from saturated C ₂ -C ₂₄ , preferably C ₄ -C ₁₃ , more preferably C ₄ -C ₁₁ dicarboxylic acids, their C ₁ -C ₂₄ , preferably C _{1 -} C ₄ , alkyl esters, their salts and mixtures thereof. Preferably, the saturated aliphatic dicarboxylic acids are selected from succinic acid, 2-ethylsuccinic acid, glutaric acid, 2-methylglutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassilic acid, hexadecanedicarboxylic acid , octadecane dicarboxylic acid and their C _1-24 alkyl esters. According to one of the preferred embodiments of this invention, the saturated aliphatic dicarboxylic acid includes mixtures containing at least 50 mol.%, preferably more than 60 mol.%, more preferably more than 65 mol.%, succinic acid, adipic acid, azelaic acid , sebacic acid, brassilic acid, their C ₁ -C ₂₄ , preferably C ₁ -C ₄ esters and mixtures thereof. According to a particularly preferred embodiment, these mixtures comprise or consist of adipic acid and azelaic acid, while containing azelaic acid in an amount of from 5 to 40 mol.%, more preferably from 10 to 35 mol.% azelaic acid, relative to the amount of adipic acid and azelaic acid.

The unsaturated aliphatic dicarboxylic acids in the a3 component of polyester i are preferably selected from itaconic acid, fumaric acid, 4-methylene pimelic acid, 3,4-bis(methylene)nonanedicarboxylic acid, 5-methylenenonanedicarboxylic acid, their C ₁ -C ₂₄ , preferably C ₁ -C ₄ , alkyl esters, their salts and mixtures thereof. According to one of the preferred embodiments of this invention, unsaturated aliphatic dicarboxylic acids include mixtures containing at least 50 mol.%, preferably more than 60 mol.%, more preferably more than 65 mol.%, itaconic acid and its C ₁ -C ₂₄ , preferably C ₁ -C ₄ esters. More preferably, the unsaturated aliphatic dicarboxylic acid includes itaconic acid.

The saturated aliphatic diols in the polyester component b1 are preferably selected from 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-undecandiol, 1,12-dodecanediol, 1,13-tridecanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, 2- methyl 1,3-propanediol, dianhydrosorbitol, dianhydromannite, dianhydroidite, cyclohexanediol, cyclohexanemethanediol, dialkylene glycols and polyalkylene glycols having a molecular weight of from 100 to 4000, such as, for example, polyethylene glycol, polypropylene glycol and mixtures thereof. Preferably, the diol component contains at least 50 mole % of one or more diols selected from 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol. More preferably, the diol component contains or consists of 1,4-butanediol.

The unsaturated aliphatic diols in the polyester component b2 are preferably selected from cis-2-butene-1,4-diol, trans-2-butene-1,4-diol, 2-butyn-1,4-diol, cis-2-pentene -1,5-diol, trans-2-pentene-1,5-diol, 2-pentyn-1,5-diol, cis-2-hexene-1,6-diol, trans-2-hexene-1,6 -diol, 2-hexine-1,6-diol, cis-3-hexene-1,6-diol, trans-3-hexene-1,6-diol, 3-hexine-1,6-diol.

The molecular weight Mn of polyester i in layer B is preferably ≧20,000, more preferably ≧40,000. The molecular weight polydispersity ratio, Mw/Mn, is preferably 1.5 to 10, more preferably 1.6 to 5, and even more preferably 1.8 to 2.7.

The molecular weights M _n and M _w can be measured using gel permeation chromatography (GPC). The determination can be performed with a chromatographic system maintained at 40°C using a set of two columns in series (particle diameters 5 µm and 3 µm with mixed porosity), a refractive index detector, chloroform as eluent (flow rate 0.5 ml/min) and polystyrene as reference.

The acid terminal content of the polyester i in layer B is preferably less than 100 meq/kg, preferably less than 60 meq/kg and even more preferably less than 40 meq/kg.

The content of terminal acid groups can be measured using the method described for the aliphatic-aromatic polyester layer A.

Preferably, the polyester i in layer B has an intrinsic viscosity (measured with an Ubbelohde viscometer for solutions of 0.2 g/dl in CHCl ₃ at 25° C.) above 0.3 dl/g, preferably from 0.3 up to 2 dl/g, more preferably from 0.4 to 1.1 dl/g.

Preferably, the polyester i in layer B is biodegradable. In the context of this invention, a biodegradable polymer is understood to mean a polymer that is biodegradable in accordance with EN 13432.

The polyester i in layer B can be synthesized according to any of the methods known in the art. In particular, it can be successfully obtained by a polycondensation reaction.

Preferably, the synthesis process may be carried out in the presence of a suitable catalyst. As examples of suitable catalysts, mention may be made of organometallic tin compounds, eg stannonic acid derivatives, titanium compounds, eg orthobutyl titanate, aluminum compounds, eg triisopropylaluminum, antimony, zinc and zirconium compounds, and mixtures thereof.

Layer composition B contains from 0.1 to 50 wt. %, preferably from 5 to 40 wt. %, relative to the sum of components from i to v, at least one polymer of natural origin. In layer B composition, the naturally occurring polymer (component i) is preferably selected from starch, chitin, chitosan, alginates, proteins such as gluten, zein, casein, collagen, gelatin, natural rubbers, resin acid and derivatives thereof. Preferably, in the layer B composition, the naturally occurring polymer is starch.

The term starch refers to all types of starch, i.e. flour, native starch, hydrolyzed starch, destructured starch, gelatinized starch, plasticized starch, thermoplastic starch, biofiller including complex starch, or mixtures thereof. Starches such as potato, corn, tapioca and pea are particularly suitable according to the invention.

Starches that are easily degradable or have high initial molecular weights, such as, for example, potato or corn starch, have proven to be particularly preferred.

The starch may be present as such or in a chemically modified form, such as, for example, in the form of starch esters having a degree of substitution from 0.2 to 2.5, starch hydroxypropylate or fatty chain modified starch.

In the case of destructured starch, reference may be made to the recommendations included in patent documents EP 0118240 and EP 0327505, implying that such starch is processed in such a way that it does not substantially contain the so-called "Maltese crosses" under an optical microscope in polarized light and the so-called " spirits" under an optical microscope with phase contrast.

Preferably, the starch is destructurized by an extrusion process at a temperature of 110 to 250°C, preferably 130 to 180°C, preferably at pressures of 0.1 to 7 MPa, preferably 0.3 to 6 MPa, preferably providing during extrusion a specific energy of more than 0.1 kWh/kg.

Destructurization of starch preferably proceeds in the presence of from 1 to 40 wt. %, relative to the mass of starch, one or more plasticizers selected from water and polyhydric alcohols containing from 2 to 22 carbon atoms. As for water, it can also be water naturally present in starch. Among the polyhydric alcohols, alcohols having 1 to 20 hydroxyl groups containing 2 to 6 carbon atoms, their ethers, thioethers, and organic and inorganic esters are preferred. Examples of polyhydric alcohols include glycerol, diglycerol, polyglycerol, pentaerythritol, polyglycerol ethoxylate, ethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, sorbitol monoacetate, sorbitol diacetate, sorbitan monoethoxylate, diethoxylate sorbitol and mixtures thereof. According to one of the preferred embodiments, the starch is destructurized in the presence of glycerol or a mixture of plasticizers, including glycerol, more preferably containing from 2 to 90 wt. % glycerin. Preferably, destructured and cross-linked starch according to this invention contains from 1 to 40 wt. % plasticizers, relative to the mass of starch.

When starch is present in the composition of layer B, it preferably has the form of particles with a circular or elliptical cross-section or, in any case, with a cross-section similar to an ellipse, having an arithmetic mean diameter of less than 1 micron and, more preferably, a mean diameter of less than 0.5 µm, measured on the basis of the major axis of the particle.

Layer composition B contains from 1 to 40 wt. %, preferably from 2 to 30 wt. %, relative to the sum of components i to v, at least one polyhydroxyalkanoate (component iii), preferably selected from the group consisting of polyesters of lactic acid, poly-ε-caprolactone, polyhydroxybutyrate, polyhydroxybutyrate valerate, polyhydroxybutyrate propanoate, polyhydroxybutyrate hexanoate, polyhydroxybutyrate decanoate, polyhydroxybutyrate dodecanoate , polyhydroxybutyrate hexadecanoate, polyhydroxybutyratoctadecanoate, poly-3-hydroxybutyrate-4-hydroxybutyrate. Preferably, the specified polyhydroxyalkanoate contains at least 80 wt. % of one or more lactic acid polyesters.

According to one preferred embodiment, the lactic acid polyesters are selected from the group consisting of poly-L-lactic acid, poly-D-lactic acid, poly-D-L-lactic acid stereocomplex, copolymers containing more than 50 mole % of said lactic acid polyesters. acids, or mixtures thereof.

Particularly preferred are polyesters of lactic acid containing at least 95 wt. % repeating units derived from L-lactic or D-lactic acid, or combinations thereof, having a molecular weight Mw greater than 50,000 and a shear viscosity of 50 to 500 Pa⋅s, preferably 100 to 300 Pa⋅s (measured according to the standard ASTM D3835 at T=190°C, shear rate = 1000 s ^-1 , D=1 mm, L/D=10).

According to a particularly preferred embodiment of the invention, the polyester lactic acid contains at least 95 wt. % of units derived from L-lactic acid, ≤5% of repeating units derived from D-lactic acid, has a melting point in the range of 135 to 180°C, a glass transition temperature (Tg) in the range of 55 to 65°C and a value MFR (measured according to ISO 1133-1 at 190°C and 2.16 kg) in the range of 1 to 50 g/10 min. Commercially available examples of lactic acid polyesters having these properties are, for example, Ingeo™ Biopolymer 4043D, 3251D and 6202D products.

The composition of layer B contains from 0 to 15 wt. %, relative to the sum of components i to v, of at least one inorganic filler (component iv), which is preferably selected from kaolin, barites, clay, talc, calcium and magnesium carbonates, iron and lead, aluminum hydroxide, diatomaceous earth, aluminum sulfate , barium sulfate, silicon dioxide, mica, titanium dioxide, wollastoniate.

According to one of the preferred embodiments of the present invention, the inorganic filler in the layer B composition comprises talc, calcium carbonate or mixtures thereof, is present in the form of particles having an arithmetic average diameter of less than 10 microns measured relative to the major axis of the particles. In fact, it has been found that fillers of the type mentioned above, which do not have the indicated arithmetic average diameter, provide significantly worse disintegration characteristics during industrial composting of objects containing them.

The layer composition also contains from 0 to 5 wt. %, preferably from 0 to 0.5 wt. %, relative to the sum of components from i to v, at least one crosslinking agent and/or chain extender (component v) to improve resistance to hydrolysis.

Said crosslinker and/or chain extender is selected from compounds having two and/or multiple functional groups, including isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxy, anhydride or divinyl ether groups, or mixtures thereof. Preferably, the crosslinker and/or chain extender contains at least one compound having two and/or multiple functional groups, including isocyanate groups. More preferably, the crosslinker and/or chain extender contains at least 25 wt. % of one or more compounds having two and/or multiple functional groups, including isocyanate groups. Especially preferred are mixtures of compounds having two and/or multiple functional groups, including isocyanate groups, with compounds having two and/or multiple functional groups, including epoxy groups, even more preferably containing at least 75 wt. % compounds having two and/or multiple functional groups, including isocyanate groups.

Compounds having di- or multifunctional groups including isocyanate groups are preferably selected from p-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4-diphenylmethane diisocyanate, 1,3-phenylene-4-chlorodiisocyanate, 1 ,5-naphthalene diisocyanate, 4,4-diphenylene diisocyanate, 3,3'-dimethyl-4,4-diphenylmethane diisocyanate, 3-methyl-4,4'-diphenylmethane diisocyanate, diphenyl ether diisocyanate, 2,4-cyclohexane diisocyanate, 2,3-cyclohexane diisocyanate , 1-methyl-2,4-cyclohexyl diisocyanate, 1-methyl-2,6-cyclohexyl diisocyanate, bis-(isocyanatecyclohexyl)-methane, 2,4,6-toluene triisocyanate, 2,4,4-diphenylether triisocyanate, polymethylene polyphenyl polyisocyanates, methylene diphenyl diisocyanate, triphenylmethane triisocyanate, 3,3'-dioluene-4,4-diisocyanate, 4,4'-methylene-bis-(2-methylphenylisocyanate), hexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,2-cyclohexylene diisocyanate and mixtures thereof. According to one preferred embodiment, the isocyanate group-containing compound is 4,4-diphenylmethane diisocyanate.

Compounds having two and/or multiple functional groups including peroxide groups are preferably selected from benzoyl peroxide, lauroyl peroxide, isononanoyl peroxide, di-(t-butylperoxyisopropyl)benzene, t-butyl peroxide, dicumyl peroxide, α,α-di- (tert-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, tert-butylcumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy)hex-3-yne, di-(4-tert-butylcyclohexyl)peroxydicarbonate, dicetylperoxydicarbonate, dimyristylperoxydicarbonate, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane, di-(2-ethylhexyl)-peroxydicarbonate and mixtures thereof.

Compounds having two and/or multiple functional groups, including carbodiimide groups, which are preferably used in the composition according to this invention, are selected from poly-(cyclooctylenecarbodiimide), poly-(1,4-dimethylenecyclohexylenecarbodiimide), 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-(naphthylenecarbodiimide), poly-(isophoronecarbodiimide), poly-(cumenecarbodiimide), p- phenylene-bis(ethyl carbodiimide), 1,6-hexamethylene-bis(ethylcarbodiimide), 1,8-octamethylene-bis(ethyl carbodiimide), 1,10-decamethylene-bis(ethylcarbodiimide), 1,12-dodecamethylene- bis(ethylcarbodiimide) and mixtures thereof.

Examples of compounds having two or more functional groups, including epoxy groups, which can be successfully used in the composition according to this invention are polyepoxides from epoxidized oils and/or from styrene-glycidyl ether-methyl methacrylate or glycidyl ether-methyl methacrylate falling into molecular weight range from 1000 to 10000 and having an epoxy number per molecule in the range of 1 to 30 and preferably 5 to 25, epoxides are selected from the group consisting of: diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, glycerol dipolyglycidyl ether , 1,2-epoxybutane, polyglycidyl ether of polyglycerol, isoprene diepoxide, and cycloaliphatic diepoxides, 1,4-cyclohexanedimethanol diglycidyl ether, glycidyl-2-methylphenyl ether, glycerol propoxylate triglycidyl ether, 1,4-butanediol diglycidyl ether, sorbitol polyglycidyl ether, diglycidyl ether glycerol ether, meta-xylenediamine tetraglycidyl ethers and diglycidyl ether or bisphenol A, and mixtures thereof.

Catalysts can also be used with compounds having two or more functional groups, including isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxy, anhydride and divinyl ether groups, such as, for example, those described above, to increase the reactivity of the functional groups. In the case of polyepoxides, fatty acid salts, preferably calcium and zinc stearates, can preferably be used.

According to a particularly preferred embodiment of the invention, the crosslinker and/or chain extender for the composition in layer B comprises compounds comprising isocyanate groups, preferably 4,4-diphenylmethane diisocyanate, and/or comprising carbodiimide groups, and/or comprising epoxy groups, preferably styrene-glycidyl ether-methyl methacrylate type.

In layer B, in addition to components i to v mentioned above, one or more other components may preferably also be present. In this case, layer B contains a composition comprising components i to v and preferably one or more polymer, not the same as components i and and iii, of synthetic or natural origin, which may or may not be biodegradable, possibly together with one or more other components.

As regards polymers other than said components i, ii and iii, of synthetic or natural origin, which may or may not be biodegradable, they may preferably be selected from the group consisting of vinyl polymers, polyesters of diacid acids and diols, other than said polyester i, polyamides, polyurethanes, polyethers, polyureas, polycarbonates and mixtures thereof.

Among vinyl polymers, polyethylene, polypropylene, their copolymers, polyvinyl alcohol, polyvinyl acetate, polyethylvinyl acetate and polyethylene vinyl alcohol, polystyrene, chlorinated vinyl polymers, polyacrylates are preferred.

Chlorinated vinyl polymers for use in this work, in addition to polyvinyl chloride, include polyvinylidene chloride, polyethylene chloride, poly-(vinyl chloride-vinyl acetate), poly-(vinyl chloride-ethylene), poly-(vinyl chloride-propylene), poly-(vinyl chloride-styrene), poly-(vinyl chloride-isobutylene) and copolymers in which polyvinyl chloride is more than 50 mol.%. These polymers may be random copolymers, block copolymers or alternating copolymers.

As regards the polyamides in the composition according to the invention, they are preferably selected from the group consisting of polyamide 6 and 6.6, polyamide 9 and 9.9, polyamide 10 and 10.10, polyamide 11 and 11.11, polyamide 12 and 12.12 and their combinations of type 6/9, 6/10, 6/11 and 6/12, mixtures thereof, as well as random copolymers and block copolymers.

Preferably, the polycarbonates in the composition of this invention are selected from the group consisting of polyalkylene carbonates, more preferably polyethylene carbonates, polypropylene carbonates, polybutylene carbonates, mixtures thereof, and random copolymers and block copolymers.

Among polyethers, preferred are compounds selected from the group consisting of polyethylene glycols, polypropylene glycols, polybutylene glycols, their copolymers and mixtures thereof, having molecular weights from 70,000 to 500,000.

Polyesters of dibasic acids and diols other than said polyester i in layer B preferably include:

i) a dicarboxylic component, comprising, relative to the total amount of the dicarboxylic component:

i1) from 20 to 100 mol.% units derived from at least one aromatic dicarboxylic acid,

i2) from 0 to 80 mole % of units derived from at least one saturated aliphatic dicarboxylic acid,

i3) 0 to 5 mole % of units derived from at least one unsaturated aliphatic dicarboxylic acid;

j) a diol component comprising, relative to the total amount of the diol component:

j1) from 95 to 100 mole % of units derived from at least one saturated aliphatic diol;

j2) 0 to 5 mole % units derived from at least one unsaturated aliphatic diol.

Preferably, the aromatic dicarboxylic acids i1, saturated aliphatic dicarboxylic acids i2, unsaturated aliphatic dicarboxylic acids i3, saturated aliphatic diols j1 and unsaturated aliphatic diols j2 for said polyesters are selected from the compounds described above for polyester i in layer B according to this invention.

In addition to the components mentioned above, the composition in layer B preferably also contains at least one other component selected from the group consisting of plasticizers, UV stabilizers, lubricants, nucleating agents, surfactants, antistatic additives, pigments, flame retardants , compatibilizers, lignin, organic acids, antioxidants, anti-mildew agents, waxes, processing aids and polymeric components, preferably selected from the group consisting of vinyl polymers, diacid polyesters and non-aliphatic-aromatic diols polyesters as described above, polyamides, polyurethanes, polyethers, polyureas or polycarbonates.

In the composition of layer B according to the present invention, in addition to the plasticizers preferably used for the preparation of destructurized starch described above, one or more plasticizers are preferably present, selected from the group consisting of phthalates, such as, for example, diisononyl phthalate, trimellitates, such as, for example, , esters of trimellitic acid with C ₄ -C ₂₀ monoalcohols, preferably selected from the group consisting of n-octanol and n-decanol, and aliphatic esters having the following structure:

R ₁ -OC(O)-R ₄ -C(O)-[-OR ₂ -OC(O)-R ₅ -C(O)-] _m -OR ₃ ,

Where:

R ₁ is selected from one or more groups including H, linear and branched, saturated and unsaturated alkyl residues of the C ₁ -C ₂₄ type, polyhydric alcohol residues esterified with C _{1 -} C ₂₄ monobasic carboxylic acids;

R ₂ contains -CH ₂ -C(CH ₃ ) ₂ -CH ₂ - and C ₂ -C ₈ alkylene groups, and contains at least 50 mol.% of the specified -CH ₂ -C(CH ₃ ) ₂ -CH ₂ - groups;

R ₃ is selected from one or more groups including H, linear and branched, saturated and unsaturated alkyl residues of the C ₁ -C ₂₄ type, polyhydric alcohol residues esterified with C ₁ -C ₂₄ monobasic carboxylic acids;

R ₄ and R ₅ are the same or different, include one or more C ₂ -C ₂₂ , preferably C ₂ -C ₁₁ , more preferably C ₄ -C ₉ alkylene, and include at least 50 mole % C ₇ alkylenes ,

m is a number from 1 to 20, preferably from 2 to 10, more preferably from 3 to 7.

Preferably, in said esters, at least one of the groups R ₁ and/or R ₃ preferably contains ≥10 mol.%, more preferably ≥20%, even more preferably ≥25 mol.%, relative to the total amount of R ₁ and/or R ₃ groups, residues of polyhydric alcohols esterified with at least one C ₁ -C ₂₄ monobasic carboxylic acid selected from the group consisting of stearic acid, palmitic acid, 9-ketostearic acid, 10-ketostearic acid and mixtures thereof . Examples of aliphatic esters of this type are disclosed in Italian patent application MI2014A000030 and PCT applications PCT/EP2015/050336, PCT/EP2015/050338.

If present in layer B of the selected plasticizers, they are preferably present in an amount of up to 10 wt. %, relative to the total mass of the composition of the layer B itself.

Lubricants are preferably selected from fatty acid esters and metal salts such as, for example, zinc stearate, calcium stearate, aluminum stearate and acetyl stearate. Preferably, the layer composition In accordance with this invention contains up to 1 wt. % lubricants, more preferably up to 0.5 wt. %, relative to the total weight of the layer B composition.

Examples of nucleating agents include sodium saccharin, calcium silicate, sodium benzoate, calcium titanate, boron nitride, isotactic polypropylene, or low molecular weight PLA. Such additives are preferably introduced in amounts up to 10 wt. % and, more preferably, from 2 to 6 wt. %, relative to the total weight of the composition.

If desired, pigments may also be added, for example titanium dioxide, clays, copper phthalocyanine, silicates, iron oxide and hydroxides, carbon black and magnesium oxide. Such additives are preferably introduced in amounts up to 10 wt. %.

Preferably, the polyesters of layers A and/or B of the multilayer film according to the present invention comprise at least 10 mole % of aromatic dicarboxylic acids and/or aliphatic dicarboxylic acids and/or diols of renewable origin. According to the present invention, products that can be considered as having a renewable origin are products obtained from sources that are by their very nature renewable and inexhaustible in the time frame of human life, and the use of which, therefore, does not adversely affect the availability of natural resources. for future generations. Examples of renewable monomers are sebacic acid, succinic acid, 2,5-furandicarboxylic acid, azelaic acid, 1,4-butanediol.

The multilayer film according to the present invention comprises at least one layer A and at least one layer B, preferably characterized by mutual ratios selected from A/B and A/B/A, where the A layer and the B layer are different from each other. The multilayer film according to the invention may preferably include one or more layers A and one or more layers B, as well as additional layers, such as, for example, tie layers or barrier layers, or metal films. In the multilayer film according to the present invention, the ratio between the plurality of layers A and the plurality of layers B is between 0.05 and 1.2. Preferably, in the multilayer film according to the present invention, the ratio between the set of layers A and the set of layers B is from 0.1 to 0.6. The multilayer film according to the invention, with an A/B and preferably A/B/A layering, has an overall thickness in which the sum of the thicknesses A of the layers is less than the thickness B of the layers, preferably less than B/2 and more preferably less than than B/3. The multilayer film according to the present invention preferably has an overall thickness of less than 50 microns, more preferably less than 15 microns, even more preferably less than 13 microns.

The thickness of the layers can preferably be measured with an electron microscope on the fracture surface in liquid nitrogen.

However, additional layers may also be present, located in an intermediate position relative to layers A and B (position A/C/B, where C is an additional layer) or non-intermediate position (position A/B/C or C/A/ B, where C is an additional layer).

The multilayer film according to this invention can be made in accordance with any method known in the art, for example, by means of a co-extrusion process, a coating/spreading process, or a lamination process. According to one of the preferred embodiments, the multilayer film according to this invention can be made using a co-extrusion process, preferably coupled with a bubble film formation process.

Equipment and specific process parameters, such as co-extrusion and film formation, for the manufacture of a multilayer film according to this invention depend on the composition and number of layers intended for the manufacture of a multilayer film. Due to the particular combination of components and layers, the multilayer film according to the invention has the characteristics to achieve an optimal balance between a high level of biodegradability, good mechanical properties, in particular a high modulus of elasticity, and significant optical transparency characteristics. This makes it particularly suitable for the manufacture of a wide range of products such as, for example, various types of packaging, in particular bags for carrying goods and bags for packaging foodstuffs, such as bags for fruits and vegetables, containing said multilayer film.

With regard to optical properties, the transmission value is greater than 90%, more preferably greater than 91%, the haze value is less than 65%, more preferably less than 55%, and the transparency is greater than 20%, more preferably greater than 40% (measured according to the ASTM standard D1003), allowing the multilayer film according to the present invention to be suitable for the applications mentioned above, are particularly preferred.

The multilayer film according to the present invention is biodegradable under home composting conditions in accordance with the UNI11355 standard. Preferably, said multilayer film is biodegradable under home composting conditions according to the UNI1135 standard when it has an overall thickness of less than 15 microns, preferably less than 13 microns.

The multilayer film according to the present invention finds use in the manufacture of mulching films due to its high disintegration at low temperatures, combined with good mechanical properties, being able to effectively perform the function of protecting the soil, for example, inhibiting the growth of weeds and reducing water consumption, without the need to remove the film after use.

Preferably, the degradation of said mulch films comprising the composition of the present invention occurs in the soil at temperatures in the range of 28° C.±2, wherein the degree of degradation can be determined visually through periodical observations. Preferably, the multilayer film according to the present invention is no longer visible after 180 days.

Hereinafter, the present invention will be illustrated on the basis of a number of examples, which are not intended to limit it.

DESCRIPTION OF EXAMPLES OF CARRYING OUT THE INVENTION

Example 1

Double layer film having A/B arrangement

Preparation of composition A (layer A): 29.7 kg/h of poly-(butylene adipate-co-butylene terephthalate) having a terephthalic acid content of 47.5 mol%, relative to the total amount of the dicarboxylic component, MFR 11 g/10 min (at 190 °C, 2.16 kg) and acidity 50 meq/kg, 9.1 kg/h polylactic acid Ingeo 3251D ("PLA"), MFR 58 g/10 min (at 190°C, 2.16 kg), 1 .0 kg/h concentrate additives, including 10 wt. % Joncryl ADR4368CS (styrene-glycidyl ether-methyl methacrylate copolymer) and 90% polylactic acid Ingeo 4043D ("PLA"), 0.2 kg/h additive concentrate comprising 10% Crodamide SR Bead manufactured by Croda and 90% poly- (butylene adipate-co-butylene terephthalate) was fed into 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°C;

throughput: 40 kg/h;

vacuum degassing in zone 8 out of 10.

The granules thus obtained had an MFR value (190°C, 2.16 kg in accordance with ISO 1133-1 "Plastics - determination of the melt mass-flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics - Part 1: Standard method (Plastics - Determination of Mass Melt Flow Rate (MFR) and Volumetric Melt Flow Rate (MVR) of Thermoplastics - Part 1: Standard Method) 7 g/10 min.

Preparation of composition B (layer B): 28.3 kg/h of poly(butylene adipate-co-butylenezelainate-co-butylene terephthalate) having an azelaic acid content of 30 mole %, based on the sum of adipic acid and azelaic acid, and a terephthalic acid content of 48, 3 mole %, based on total dicarboxylic component, MFR 5 g/10 min (at 190° C., 2.16 kg) and acidity 47 meq/kg, 1.4 kg/h Ingeo 4043D ("PLA") polylactic acid, MFR 2.7 g/10 min (at 190°C, 2.16 kg), 16 kg/h thermoplastic corn starch, 0.1 kg/h Almatex PD-4440 manufactured by Anderson Development Company, 0.1 kg/h hrs of Crodamide ER microgranules manufactured by Croda and 0.1 kg/hr of Carbodilite HMV15CA manufactured by Nisshinbo Chemical Inc. were fed into a model OMC EBV60/36 twin screw extruder operating under the following conditions:

screw diameter (D)=58 mm;

L/D=36;

screw rotation speed = 160 rpm;

temperature profile = 60-150-180-210×4-150×2°C;

throughput: 46.1 kg/h;

vacuum degassing in zone 8 out of 10.

The granules thus obtained had an MFR value (160°C, 5 kg in accordance with ISO 1133-1 "Plastics - determination of the melt mass-flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics - Part 1: Standard method") 2.4 g/10 min.

Composition A and Composition B were then fed simultaneously to the co-extruder to form a two-layer blown film having an A/B arrangement. To this end, Composition A was fed at a throughput of 3.3 kg/h into an extruder with a screw diameter of 35 mm and L/D 30, operating at 13 rpm with a temperature profile of 100-170×4. In parallel, the Composition was fed through two extruders B, the first of which had a screw diameter of 35 mm, L / D 30, a rotation speed of 12 rpm with a temperature profile of 80-154 × 4, a productivity of 3.3 kg / h, the second had a screw diameter of 40 mm, L/D 30, rotation speed 74 rpm with a temperature profile of 80-145×4 and a throughput of 28.3 kg/h. After melting, the two compositions were combined in a blown co-extrusion die having a slot gap of 0.9 mm and an L/D of 9 set at 170°C, feeding the multilayer structure into the film forming process at a blow ratio of 4.5 and a stretch ratio of 20.2 .

The film thus obtained (10 microns in total, 10% layer A, 90% layer B) was then characterized in terms of mechanical and optical properties (Table 1).

Example 2

Three-layer film having A/B/A arrangement

Composition A and Composition B according to Example 1 were simultaneously fed into a co-extruder to form a three-layer blown film having an A/B/A arrangement. To this end, Composition A was loaded at a throughput of 3.3 kg/h into a first extruder having a screw diameter of 35 mm and an L/D of 30, operating at 14 rpm with a temperature profile of 100-170×4, and at a throughput of 3 .3 kg/h into a second extruder with a screw diameter of 35 mm and L/D 30, operating at 13 rpm with a temperature profile of 100-170×4. Composition B was loaded at 28.3 kg/h into an extruder having a screw diameter of 40 mm and an L/D of 30 operating at 74 rpm with a temperature profile of 80-154×4. After melting, the two compositions were combined in a blown co-extrusion die having a slot gap of 0.9 mm and an L/D ratio of 9 set at 170°C, feeding the multilayer structure into the film forming process at a blow ratio of 4.5 and a stretch ratio of 20, 2.

The film thus obtained (10 microns in total, 20% layer A evenly distributed between two layers, 80% layer B) was then characterized in terms of mechanical and optical properties (Table 1).

Example 3 (comparative)

Manufacture of a single layer film comprising Composition B

Composition B according to Example 1 was simultaneously fed into a co-extruder to form a single layer blown film having a B/B/B arrangement. To this end, Composition B was loaded at a throughput of 2.8 kg/h into a first extruder having a screw diameter of 35 mm and an L/D of 30, operating at 18 rpm with a temperature profile of 100-145×4, and at a throughput of 24 .3 kg / h - into the second extruder with a screw diameter of 40 mm and L / D 30, operating at 63 rpm with a temperature profile of 80-145 × 4, and at a throughput of 2.8 kg / h - into the third extruder with screw diameter 35 mm and L/D 30, operating at 18 rpm with 100-145×4. The blown coextrusion die has a slot gap of 0.9 mm and an L/D ratio of 9, set at 145°C, feeding the monolayer structure into the film forming process at a blow ratio of 4.5 and a stretch ratio of 20.2.

The film thus obtained (10 microns in total, 100% composition B) was then characterized in terms of mechanical and optical properties (Table 1).

Example 4

Three-layer film having A/B/A arrangement

Preparation of composition A (layer A): 31.4 kg/h of poly-(butylene adipate-co-butylene terephthalate) having a terephthalic acid content of 47.5 mol%, relative to the total amount of the dicarboxylic component, MFR 11 g/10 min (at 190 °C, 2.16 kg) and acidity 50 meq/kg, 7.6 kg/h polylactic acid Ingeo 3251D ("PLA"), MFR 58 g/10 min (at 190°C, 2.16 kg), 0 ,8 kg/h concentrate additives, including 10 wt. % Joncryl ADR4368CS (styrene-glycidyl ether-methyl methacrylate copolymer) and 90% polylactic acid Ingeo 4043D ("PLA"), 0.2 kg/h additive concentrate comprising 10% Crodamide SR Bead manufactured by Croda and 90% poly -(butylene adipate-co-butylene terephthalate) was fed into a twin screw extruder model OMC EBV60/36 operating under the conditions indicated for layer A in Example 1.

The granules thus obtained had an MFR value (190° C., 2.16 kg according to ISO 1133-1) of 7.5 g/10 min.

Composition A according to Example 4 and Composition B according to Example 1 were simultaneously fed into a coextruder to form a three-layer blown film having an A/B/A arrangement. To this end, Composition A was loaded at a throughput of 2.9 kg/h into a first extruder having a screw diameter of 35 mm and an L/D of 30, operating at 11 rpm with a temperature profile of 60-170x4, and at a throughput of 2 .9 kg/h into a second extruder with a screw diameter of 35 mm and L/D 30, operating at 11 rpm with a 60-170×4 temperature profile. Composition B was loaded at 24.2 kg/h into an extruder having a screw diameter of 40 mm and an L/D of 30, operating at 64 rpm with a temperature profile of 80-145×4. After melting, the two compositions were combined in a blown co-extrusion die having a slot gap of 0.9 mm and an L/D of 9 set at 170°C, feeding the multilayer structure into the film forming process at a blow ratio of 4.5 and a stretch ratio of 20.2 .

The film thus obtained (10 microns in total, 20% layer A evenly distributed between two layers, 80% layer B) was then characterized in terms of mechanical and optical properties (Table 1).

Example 5

Three-layer film having A/B/A arrangement

Preparation of composition A (layer A): 16 kg/h poly-(butylene sebacate), MFR 3.7 g/10 min (at 150° C., 2.16 kg) and acidity 25 meq/kg, 20 kg/h poly- (butylene adipate-co-butylene terephthalate) having a terephthalic acid content of 47.5 mol%, relative to the total amount of the dicarboxylic component, an MFR of 5.1 g/10 min (at 190° C., 2.16 kg) and an acidity of 37 meq/kg , 4 kg/h polylactic acid Ingeo 4043D ("PLA"), MFR 2.5 g/10 min (at 190° C., 2.16 kg), 0.1 kg/h Crodamide ER microgranules manufactured by Croda were supplied into an OMC EBV60/36 twin screw extruder operating under the following conditions:

screw diameter (D)=58 mm;

L/D=36;

screw rotation speed = 160 rpm;

temperature profile=60-120-160×5-150×2°C;

throughput: 40.1 kg/h;

vacuum degassing in zone 8 out of 10.

The granules thus obtained had an MFR value (190°C, 2.16 kg in accordance with ISO 1133-1 "Plastics - determination of the melt mass-flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics - Part 1: Standard method") 6 g/10 min.

Then, Composition A according to Example 5 and Composition B according to Example 1 were fed simultaneously into a co-extruder to form a three-layer blown film having an A/B/A arrangement. To this end, Composition A was fed at a throughput of 2.8 kg/h into an extruder with a screw diameter of 35 mm and L/D 30, operating at 11 rpm with a temperature profile of 60-125×4. Composition B was fed through an extruder with a screw diameter of 40 mm and L/D 30, operating at 66 rpm with a temperature profile of 80-145×4. After melting, the two compositions were combined in a blown co-extrusion die having a slot gap of 0.9 mm and an L/D of 9 set at 145°C, feeding the multilayer structure into the film forming process at a blow ratio of 4.5 and a stretch ratio of 20.2 .

The film thus obtained (10 microns in total, 20% layer A, 80% layer B) was then characterized in terms of mechanical and optical properties (Table 1).

Example 6

Three-layer film having A/B/A arrangement

Preparation of composition A (layer A): poly(butylene succinate-co-butylene zelainate) having an azelaic acid content of_25 mol%, relative to the total amount of the dicarboxylic component, MFR 6 g/10 min (at 190° C., 2.16 kg) and acidity 46 meq/kg.

Composition A according to Example 6 and Composition B according to Example 1 were simultaneously fed into a co-extruder to form a three-layer blown film having an A/B/A arrangement. To this end, Composition A was loaded at a throughput of 2.8 kg/h into a first extruder having a screw diameter of 35 mm and an L/D of 30, operating at 12 rpm with a temperature profile of 60-120×4, and at a throughput of 2 .8 kg/h into a second extruder with a screw diameter of 35 mm and L/D 30, operating at 12 rpm with a temperature profile of 60-120×4. Composition B was loaded at 24.3 kg/h into an extruder having a screw diameter of 40 mm and an L/D of 30, operating at 63 rpm with a temperature profile of 80-145×4. After melting, the two compositions were combined in a blown co-extrusion die having a slot gap of 0.9 mm and an L/D of 9 set at 145°C, feeding the multilayer structure into the film forming process at a blow ratio of 4.5 and a stretch ratio of 16.8 .

The film thus obtained (12 microns in total, 20% layer A evenly distributed between the two layers, 80% layer B) was then characterized in terms of mechanical and optical properties (Table 1).

Example 7

Three-layer film having A/B/A arrangement

Preparation of composition A (layer A): poly-(butylene adipate-co-butylene terephthalate) having a terephthalic acid content of 47.5 mol%, relative to the total amount of the dicarboxylic component, MFR 3.9 g/10 min (at 190°C, 2 .16 kg) and acidity 33 meq/kg.

Composition A according to Example 7 and Composition B according to Example 1 were simultaneously fed into a coextruder to form a three-layer blown film having an A/B/A arrangement. To this end, Composition A was loaded at a throughput of 2.8 kg/h into a first extruder having a screw diameter of 35 mm and an L/D of 30, operating at 16 rpm with a temperature profile of 60-145×4, and at a throughput of 2 .8 kg/h into a second extruder with a screw diameter of 35 mm and L/D 30, operating at 16 rpm with a temperature profile of 60-145×4. Composition B was loaded at 24.3 kg/h into an extruder having a screw diameter of 40 mm and an L/D of 30, operating at 63 rpm with a temperature profile of 80-145×4. After melting, the two compositions were combined in a blown coextrusion die having a slot gap of 0.9 mm and an L/D of 9 set at 145°C, feeding the multilayer structure into the film forming process at a blow ratio of 3.6 and a stretch ratio of 25.2 .

The film thus obtained (10 microns in total, 20% layer A evenly distributed between the two layers, 80% layer B) was then characterized in terms of mechanical and optical properties (Table 1).

Claims (37)

1. A multilayer film containing at least one first layer A and at least one second layer B, in which layers A and B have an A/B/A mutual arrangement, where layer A and layer B are different from each other, in which layer A contains an aliphatic and/or aliphatic-aromatic biodegradable polyester and in which layer B contains: i) from 30 to 95 wt.%, relative to the sum of components i to v, of at least one polyester, comprising: a) a dicarboxylic component, comprising, relative to the total amount of the dicarboxylic component: a1) from 35 to 70 mol.% units derived from at least one aromatic dicarboxylic acid, a2) from 30 to 65 mol.% units derived from at least one saturated aliphatic dicarboxylic acid, and a3) from 0 to 5 mol.% units derived from at least one unsaturated aliphatic dicarboxylic acid; And b) a diol component comprising, relative to the total amount of the diol component: b1) from 95 to 100 mole % of units derived from at least one saturated aliphatic diol, and b2) 0 to 5 mole % of units derived from at least one unsaturated aliphatic diol; ii) from 0.1 to 40 wt.%, relative to the sum of components i to v, starch; iii) from 1 to 30% by weight, relative to the sum of components i to v, of at least one lactic acid polyester; iv) from 0 to 15 wt.%, relative to the sum of components i to v, at least one inorganic filler; And v) from 0 to 5 wt.%, relative to the sum of components from i to v, at least one crosslinking agent and/or chain extender, including at least one compound having two and/or multiple functional groups, including isocyanate, peroxide , carbodiimide, isocyanurate, oxazoline, epoxy, anhydride, divinyl ether groups and mixtures thereof. 2. The multilayer film of claim 1, wherein said aliphatic-aromatic polyester in layer A contains: c) a dicarboxylic component, comprising, relative to the total amount of the dicarboxylic component: c1) from 35 to 70 mol.% units derived from at least one aromatic dicarboxylic acid, c2) from 30 to 65 mole % of units derived from at least one saturated aliphatic dicarboxylic acid, and c3) 0 to 5 mole % of units derived from at least one unsaturated aliphatic dicarboxylic acid; And d) a diol component comprising, relative to the total amount of the diol component: d1) 95 to 100 mole % of units derived from at least one saturated aliphatic diol, and d2) 0 to 5 mole % units derived from at least one unsaturated aliphatic diol. 3. The multilayer film of claim 2 wherein the saturated aliphatic dicarboxylic acids in component c2 comprise mixtures containing at least 50 mole % of at least one acid selected from succinic acid, adipic acid, azelaic acid, sebacic acid, brassyl acids, their C ₁ -C ₂₄ , preferably C ₁ -C ₄ esters and mixtures thereof. 4. The multilayer film of claim 3 wherein the saturated aliphatic dicarboxylic acids in the c2 component are selected from adipic acid and azelaic acid or mixtures thereof. 5. Multilayer film according to any one of paragraphs. 1-4, in which, in addition to said aliphatic and/or aliphatic-aromatic polyester in layer A, said layer A contains from 1 to 40 wt.%, relative to the entire layer A, of at least one polyhydroxyalkanoate. 6. Multilayer film according to any one of paragraphs. 1-5, wherein the saturated aliphatic dicarboxylic acid of the polyester component a2 in layer B comprises mixtures containing at least 50 mole % of at least one acid selected from succinic acid, adipic acid, azelaic acid, sebacic acid, brassic acid , their C ₁ -C ₂₄ , preferably C ₁ -C ₄ esters and mixtures thereof. 7. The multilayer film of claim 6, wherein the saturated aliphatic dicarboxylic acids in component a2 are selected from adipic acid and azelaic acid, or mixtures thereof. 8. Multilayer film according to any one of paragraphs. 1-7, characterized by a transmission value of more than 90%, a haze value of less than 65% and a transparency of more than 20%, measured in accordance with ASTM D1003. 9. Multilayer film according to any one of paragraphs. 1-8, which is biodegradable under home composting conditions in accordance with the UNI 11355 standard. 10. Multilayer film according to any one of paragraphs. 1-9, in which the composition of layer A does not contain starch. 11. Multilayer film according to any one of paragraphs. 1-10, wherein the starch in layer B composition is potato, corn, tapioca or pea starch. 12. The multilayer film of claim 11 wherein the starch in the layer B composition is potato or corn starch. 13. Multilayer film according to any one of paragraphs. 1-12, wherein the starch in layer B composition is thermoplastic starch. 14. Multilayer film according to any one of paragraphs. 1-13, in which the composition of layer B contains from 2 to 30 wt.%, relative to the sum of components i to v, at least one complex lactic acid polyester. 15. Packaging, including a multilayer film according to any one of paragraphs. 1-14. 16. Packaging according to claim 15, selected from product carrying bags and food packaging bags. 17. Packaging according to claim 16, which is a bag for vegetables and fruits. 18. Mulching film, including a multilayer film according to any one of paragraphs. 1-14.