Biodegradable laminated film and containers made from it

Abstract

A biodegradable laminate film having a layer structure A / B, in which layer A having a thickness of 0.5-7 μm comprises a polyurethane or acrylate adhesive, and layer B having a thickness of 5-150 μm comprises an aliphatic polyester and / or an aliphatic-aromatic polyester, the aliphatic-aromatic polyester being composed of: b1-i) 30-70 mol % of a C6-C18 aliphatic dicarboxylic acid, based on components b1-i and b1-ii; b1-ii) 30-70 mol % of an aromatic dicarboxylic acid, based on components b1-i and b1-ii; b1-iii) 98-100 mol % of 1,3-propanediol or 1,4-butanediol, based on components b1-i and b1-ii; b1-iv) 0-2 wt % of a chain extender and / or branching agent, based on components b1-i to b1-iii. A food and / or beverage container comprising a substrate and a biodegradable laminate film coating.

Description

Detailed Description of the Invention

[0001] [Technical field] The present invention relates to a biodegradable laminate film having a layer structure A / B, in which layer A having a thickness of 0.5-7 μm comprises a polyurethane or acrylate adhesive and layer B having a thickness of 5-150 μm comprises an aliphatic polyester and / or an aliphatic-aromatic polyester, the aliphatic-aromatic polyester being configured as follows: b1-i) 30 to 70 mol % of C6 to C18 dicarboxylic acids, based on components b1-i and b1-ii; b1-ii) 30 to 70 mol % of terephthalic acid, based on components b1-i and b1-ii; b1-iii) 98 to 100 mol % of 1,3-propanediol or 1,4-butanediol, based on components b1-i and b1-ii; b1-iv) 0 to 2 wt.-%, based on components b1-i and b1-iii, of a chain extender and / or branching agent.

[0002] Furthermore, the present invention relates to the use of said laminated film for coating a substrate, in particular paper or cardboard.

[0003] In particular, the present invention relates to the use of a film on a substrate to construct a food or beverage container. The container can be rigid, semi-rigid or flexible.

[0004] Packaging is used especially in the food and beverage industry. They often consist of composite films bonded together by a suitable adhesive, at least one of the films being a polymeric film. There is a high demand for biodegradable composite film packaging that can be disposed of by composting after use.

[0005] A variety of approaches have been taken in the literature to date.

[0006] WO 2010 / 034712 describes a method for extrusion coating paper with biodegradable polymers. In general, no adhesive is used in this method. The coated paper obtainable by the method described in WO 2010 / 034712 is not suitable for all applications due to limited adhesion to paper, mechanical properties, barrier properties, and biodegradability of the paper composite.

[0007] WO 2012 / 013506 describes the use of aqueous polyurethane dispersion adhesives for the manufacture of composite films that are partially industrially compostable. Decomposition in industrial composting plants occurs under high humidity, in the presence of certain microorganisms, and at a temperature of about 55°C. The demands on flexible packaging continue to increase in terms of their biodegradability, so that the demand for home compostability is now frequently required for many applications. The composite films described in WO 2012 / 013506 do not fully meet this standard, and are not suitable for all flexible packaging applications in terms of their mechanical and barrier properties.

[0008] It was therefore an object of the present invention to provide a laminated film which is improved in terms of biodegradability, preferably home compostable, has good adhesion to a substrate, preferably paper, and also meets other requirements.

[0009] Surprisingly, the laminated film described at the beginning of this document meets these criteria.

[0010] The invention is described in more detail below.

[0011] Layer A may also be referred to as an adhesive layer and provides the bond between layer B and the substrate. Layer A has a thickness of 0.5-7 μm and contains a polyurethane or acrylate adhesive.

[0012] Preferably, the adhesive in Layer A consists essentially of at least one polyurethane dispersed in water as a polymeric binder, as described in detail in WO 2012 / 013506, and optionally additives such as fillers, thickeners, defoamers, etc. Essential features of the polyurethane adhesives described in WO 2012 / 013506, to which explicit reference is made, are listed below:

[0013] The polymeric binder is preferably present in water as a dispersion or also in a mixture of water and a water-soluble organic solvent, preferably having a boiling point below 150° C. (1 bar). Water is particularly preferred as the sole solvent. Water or other solvents are not included in the weight data of the adhesive composition.

[0014] Preferably, the polyurethane dispersion adhesive is biodegradable. Biodegradability within the meaning of the present application is obtained, for example, when the ratio of gaseous carbon released in the form of CO2 to the total carbon content of the material used, measured according to the ISO 14855 (2005) standard, is at least 30% after 20 days, preferably at least 60% or at least 80%.

[0015] The polyurethane preferably comprises, on the one hand, mainly polyisocyanates, in particular diisocyanates, and, on the other hand, polyester diols and difunctional carboxylic acids as reactants. Preferably, the polyurethane is composed of at least 40% by weight, more preferably at least 60% by weight, very particularly preferably at least 80% by weight of diisocyanates, polyester diols and difunctional carboxylic acids.

[0016] The polyurethane may be amorphous or semi-crystalline. If the polyurethane is semi-crystalline, the melting point is preferably below 80° C. Preferably, the polyurethane contains polyester diol for this purpose in an amount of more than 10% by weight, more than 50% by weight or at least 80% by weight, based on the polyurethane. Particularly suitable are the polyurethane dispersions of BASF SE, which are commercially available under the name Epotal®.

[0017] Overall, the polyurethane is preferably composed of: a) diisocyanates, b) Diols, of which b1) 10 to 100 mol % based on the total amount of diol (b) is a polyester diol and has a molecular weight of 500 to 5000 g / mol; b2) diols, of which 0 to 90 mol %, based on the total amount of diol (b), have a molecular weight of 60 to 500 g / mol; c) at least one difunctional carboxylic acid selected from dihydroxycarboxylic acids and diaminocarboxylic acids; d) optionally further polyhydric compounds different from the monomers (a) to (c) which contain reactive groups which are alcoholic hydroxyl groups, primary or secondary amino groups, or isocyanate groups, and e) Optionally, a monovalent compound different from the monomers (a) to (d) having a reactive group which is an alcoholic hydroxyl group, a primary or secondary amino group, or an isocyanate group.

[0018] In particular, a home-compostable adhesive in layer A as described in International Application PCT / EP2021 / 054570 is preferred. The essential features of the polyurethane adhesive described in International Application PCT / EP2021 / 054570, which are expressly referenced herein, are listed below:

[0019] The aqueous polyurethane dispersion adhesive of International Application PCT / EP2021 / 054570 is suitable for producing a composite film that is biodegradable under home composting conditions (25±5°C), wherein at least one layer B and a second substrate are bonded using a polyurethane dispersion adhesive A, At least one of the substrates is a polymeric film that is biodegradable under home composting conditions, at least 60% by weight of the polyurethane being: (a) at least one diisocyanate (b) at least one polyester diol, and (c) at least one difunctional carboxylic acid selected from dihydroxycarboxylic acids and diaminocarboxylic acids; It consists of: the polyurethane has either a glass transition temperature of less than 20°C and no melting point greater than 20°C, or a melting point greater than 20°C with an enthalpy of fusion of less than 10 J / g; Preferably, layer A of the polyurethane adhesive decomposes under home composting conditions in CO2 and water to more than 90% by weight within 360 days, preferably layer A of the polyurethane adhesive is home compostable, Preferably, the laminated film A / B produced from above is biodegradable under home composting conditions if, after aerobic composting at 25±5° C. for a period of up to 180 days, at most 10% of the original dry weight of the material is present in the >2 mm sieve fraction.

[0020] Preferably, the polyurethane adhesive, the film comprising Layer B, and / or the substrate, and / or the composite film are home compostable.

[0021] Particularly suitable are polyurethane dispersions available under the trade name Epotal® Eco from BASF SE.

[0022] The layer B according to the invention has a layer thickness of 5 to 150 μm and comprises an aliphatic polyester and / or an aliphatic-aromatic polyester, the aliphatic-aromatic polyester being constructed as follows: b1-i) 30 to 70 mol % of C6 to C18 dicarboxylic acids, based on components b1-i and b1-ii; b1-ii) 30 to 70 mol % of terephthalic acid, based on components b1-i and b1-ii; b1-iii) 98 to 100 mol % of 1,3-propanediol or 1,4-butanediol, based on components b1-i and b1-ii; b1-iv) 0 to 2 wt.-%, based on components b1-i and b1-iii, of a chain extender and / or branching agent.

[0023] Aliphatic polyesters are understood to mean, for example, the polyesters described in further detail in WO 2010 / 034711, to which express reference is made herein.

[0024] The polyesters (i) of WO 2010 / 034711 are generally structured as follows: ia) 80 to 100 mole % succinic acid, based on components ia to ib; ib) 0 to 20 mole % of one or more C6 to C20 dicarboxylic acids, based on components ia to ib; ic) 99 to 102 mol %, preferably 99 to 100 mol %, of 1,3-propanediol or 1,4-butanediol, based on components ia to ib; id) 0 to 1 wt. % of a chain extender or branching agent, based on components ia to ic;

[0025] The synthesis of polyesters i of WO 2010 / 034711 is preferably carried out by direct polycondensation reaction of the individual components. In this case, a dicarboxylic acid derivative is reacted directly with a diol in the presence of a transesterification catalyst to form a polycondensate with high molecular weight. On the other hand, copolyesters can also be obtained by transesterification of polybutylene succinate (PBS) with C6-C20 dicarboxylic acids in the presence of a diol. Zinc, aluminum and especially titanium catalysts are commonly used as catalysts. Titanium catalysts such as tetra(isopropyl)orthotitanate, and especially tetraisobutoxytitanate (TBOT), have the advantage of a lower residual amount of catalyst remaining in the product or a lower toxicity of downstream products of the catalyst compared to tin, antimony, cobalt and lead catalysts such as tin dioctanoate, which are frequently used in the literature. This situation is particularly important in the case of biodegradable polyesters, since they are released directly into the environment.

[0026] Furthermore, the polyesters mentioned can be prepared by the methods described in JP 2008-45117 and EP 488617(A). It has been found to be advantageous to first react components a-c to form a prepolyester having a VZ of 50-100 mL / g, preferably 60-80 mL / g, which is then reacted in a chain extension reaction with a chain extender id, such as a diisocyanate or epoxide-containing polymethacrylate, to form a polyester i having a VZ of 100-450 mL / g, preferably 150-300 mL / g.

[0027] The acid component ia used is 80-100 mol %, preferably 90-99 mol %, more preferably 92-98 mol % succinic acid, based on the acid components a and b. Succinic acid is obtainable by petrochemical means, preferably from renewable raw materials, as described, for example, in EP 2 185 682 (A). EP 2 185 682 (A) discloses a biotechnological process for the production of succinic acid and 1,4-butanediol starting from different carbohydrates using microorganisms of the order Pasteurellaceae.

[0028] The acid component ib is used in an amount of 0 to 20 mol %, preferably 1 to 10 mol %, more preferably 2 to 8 mol %, based on the acid components ia and ib.

[0029] C6-C20 dicarboxylic acids ib especially mean adipic acid, succinic acid, azelaic acid, sebacic acid, brassylic acid and / or C18 dicarboxylic acids. Succinic acid, azelaic acid, sebacic acid and / or brassylic acid are preferred. The above acids are available from renewable raw materials. For example, sebacic acid is available from castor oil. Such polyesters are characterized by excellent biodegradation behavior [reference: Polym. Degr. Stab. 2004, 85, 855-863].

[0030] The dicarboxylic acids ia and ib can be used either as free acids or in the form of ester-forming derivatives. In particular, di-C1-C6-alkyl esters, such as dimethyl, diethyl, di-n-propyl, di-isopropyl, di-n-butyl, di-isobutyl, di-t-butyl, di-n-pentyl, di-isopentyl or di-n-hexyl esters, can be mentioned as ester-forming derivatives. Anhydrides of the dicarboxylic acids can also be used. The dicarboxylic acids or their ester-forming derivatives can be used individually or as mixtures.

[0031] The diols 1,3-propanediol and 1,4-butanediol are also available from renewable sources. Mixtures of the two diols can also be used. 1,4-butanediol is the preferred diol because the copolymer formed has a higher melting temperature and better crystallization.

[0032] Usually, at the beginning of the polymerization, the diol (component ic) is adjusted relative to the acids (components ia and ib) such that the ratio of diol to diacid is 1.0:1 to 2.5:1, preferably 1.3:1 to 2.2:1. Excess diol amounts are removed during the polymerization to obtain an approximately equimolar ratio at the end of the polymerization. Approximately equimolar means a diacid / diol ratio of 0.98 to 1.00.

[0033] In one embodiment, 0-1 wt. %, preferably 0.1-0.9 wt. %, more preferably 0.1-0.8 wt. % of branching agents id and / or chain extenders i-d' are used, based on the total weight of components ia-ib, and are selected from the group consisting of polyfunctional isocyanates, isocyanurates, oxazolines, carboxylic acid anhydrides such as maleic anhydride, epoxides (especially epoxide-containing poly(meth)acrylates), at least trifunctional alcohols or at least trifunctional carboxylic acids. Generally, no branching agents are used, only chain extenders.

[0034] Suitable difunctional chain extenders include toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthylene-1,5-diisocyanate or xylylene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate or methylene-bis(4-isocyanatocyclohexane). Isophorone diisocyanate and, in particular, 1,6-hexamethylene diisocyanate are particularly preferred.

[0035] Aliphatic polyesters i refer in particular to polyesters such as polybutylene succinate (PBS), polybutylene succinate-co-adipate (PBSA), polybutylene succinate-co-sebacate (PBSSe), polybutylene succinate-co-azelate (PBSAz) or polybutylene succinate-co-brasslate (PBSBr). Aliphatic polyesters PBS and PBSA are marketed, for example, by Mitsubishi under the name BioPBS®. More recent developments are described in WO 2010 / 034711.

[0036] The polyesters i generally have a number average molecular weight (Mn) in the range of 5000 to 100000 g / mol, in particular in the range of 10000 to 75000 g / mol, preferably in the range of 15000 to 50000 g / mol, a weight average molecular weight (Mw) of 30000 to 300000 g / mol, preferably 60000 to 200000 g / mol, and an Mw / Mn ratio of 1 to 6, preferably 2 to 4. The viscosity number is in the range of 30 to 450 g / mL, preferably 100 to 400 g / mL (measured in o-dichlorobenzene / phenol (50 / 50 by weight)). The melting point is in the range of 85 to 130 °C, preferably in the range of 95 to 120 °C. The MVR range according to DIN EN 1133-1 is 8 to 50 cm 3 / 10 minutes, especially 15-40cm 3 / 10 min (190°C, 2.16 kg).

[0037] The aliphatic polyesters of layer B also include polycaprolactone (PCL), polyhydroxyalkanoates such as poly-3-hydroxybutyrate (PHB), poly-3-hydroxybutyrate-co-3-hydroxyvalerate (P(3HB)-co-P(3HV)), poly-3-hydroxybutyrate-co-4-hydroxybutyrate (P(3HB)-co-P(4HB)) and poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P(3HB)-co-P(3HH)), and in particular polylactic acid (PLA) is used.

[0038] Polylactic acid b2 having the following property profile is preferred: Melt volume rate (MVR at 190°C and 2.16 kg according to ISO 1133-1 EN is 0.5 to 100 cm 3 / 10 minutes, especially 5~50cm 3 / 10 minutes) Melting point below 240°C; Glass transition temperature (Tg) above 55°C Moisture content less than 1000ppm Residual monomer content (lactide) less than 0.3% Molecular weight greater than 80,000 daltons.

[0039] Preferred polylactic acids are crystalline polylactic acid types from NatureWorks such as Ingeo® 6201D, 6202D, 6251D, 3051D, and 3251D, especially 4043D and 4044D, as well as polylactic acids from Total Corbion such as Luminy® L175 and LX175 Corbion, and polylactic acids from Hisun such as Revode® 190 or 110. Not only polylactic acids from Total Corbion such as Luminy® L175 and LX175 Corbion, and Hisun such as Revode® 190 or 110, but also amorphous polylactic acid grades such as Ingeo® 4060D from NatureWorks may be suitable.

[0040] The aliphatic-aromatic polyesters b1 in layer B are understood to be linear chain-extended polyesters and optionally branched chain-extended polyesters, for example as described in WO 96 / 15173-15176 or WO 98 / 12242, to which explicit reference is made. Blends of different partially aromatic polyesters are also considered. Interesting recent developments are based on renewable raw materials (see WO 2010 / 034689). In particular, polyesters b1 include products such as ecoflex® (BASF SE).

[0041] Preferred polyesters b1 include polyesters containing the following as essential components: b1-i) 30 to 70 mol %, preferably 40 to 60 mol %, more preferably 50 to 60 mol %, based on the components b1-i) and b1-ii), of aliphatic dicarboxylic acids or mixtures thereof, preferably as described below: adipic acid, in particular azelaic acid, sebacic acid and brassylic acid, b1-ii) 30 to 70 mol %, preferably 40 to 60 mol %, more preferably 40 to 50 mol %, based on components b1-i) and b1-ii), of an aromatic dicarboxylic acid or a mixture thereof, preferably as described below: terephthalic acid, b1-iii) 98 to 100 mol % of 1,4-butanediol and 1,3-propanediol, based on components b1-i) and b1-ii); and b1-iv) 0 to 2 wt.-%, preferably 0.1 to 1 wt.-%, based on components b1-i) to b1-iii), of a chain extender, in particular a di- or polyfunctional isocyanate, preferably hexamethylene diisocyanate, and optionally a branching agent, preferably trimethylolpropane, pentaerythritol and in particular glycerol.

[0042] The aliphatic diacids and the corresponding derivatives b1-i generally have from 6 to 18 carbon atoms, preferably from 9 to 14 carbon atoms. They can be both linear and branched.

[0043] Examples are adipic acid, azelaic acid, sebacic acid, brassylic acid and suberic acid (suberic acid). The dicarboxylic acids or their ester-forming derivatives can be used individually or as mixtures of two or more of them.

[0044] Preferably, adipic acid, azelaic acid, sebacic acid, brassylic acid, or their respective ester-forming derivatives or mixtures thereof are used, with azelaic acid or sebacic acid, or their respective ester-forming derivatives or mixtures thereof being particularly preferred.

[0045] In particular, the following aliphatic-aromatic polyesters are preferred: polybutylene adipate-co-terephthalate (PBAT), polybutylene adipate-co-azelate-terephthalate (PBAAzT), polybutylene adipate-co-sebacate-terephthalate (PBASeT), polybutylene azelate-co-terephthalate (PBAzT) and polybutylene sebacate-co-terephthalate (PBSEt), as well as mixtures of these polyesters.

[0046] Particularly preferred are polybutylene adipate-co-azelate-terephthalate (PBAAzT), polybutylene adipate-co-sebacate-terephthalate (PBASeT), polybutylene azelate-co-terephthalate (PBAzT) and polybutylene sebacate-co-terephthalate (PBSeT), as well as blends of polybutylene adipate-co-terephthalate (PBAT) with polybutylene azelate-co-terephthalate (PBAzT) and polybutylene sebacate-co-terephthalate (PBSeT), due to their good home compostability according to Australian Standards AS5810-2010 and ISO 14855-1 (2012).

[0047] The aromatic dicarboxylic acids or their ester-forming derivatives b1-ii can be used individually or as a mixture of two or more of them. Terephthalic acid or its ester-forming derivatives, such as dimethyl terephthalate, are particularly preferred.

[0048] The diols b1-iii, 1,4-butanediol and 1,3-propanediol, are available as renewable raw materials. Mixtures of the above diols can also be used.

[0049] Generally, 0-1% by weight, preferably 0.1-1.0% by weight, more preferably 0.1-0.3% by weight, of a branching agent based on the total weight of the polyester, and / or 0-1% by weight, preferably 0.1-1.0% by weight, of a chain extender (b1-vi) based on the total weight of the polyester is used. Preferably, a di- or polyfunctional isocyanate, preferably hexamethylene diisocyanate, is used as a chain extender, and preferably a polyol, such as trimethylolpropane, pentaerythritol, in particular glycerol, is used as a branching agent.

[0050] The polyester b1 generally has a number average molecular weight (Mn) in the range of 5000 to 100000 g / mol, in particular in the range of 10000 to 75000 g / mol, preferably in the range of 15000 to 38000 g / mol, a weight average molecular weight (Mw) of 30000 to 300000 g / mol, preferably 60000 to 200000 g / mol, and an Mw / Mn ratio of 1 to 6, preferably 2 to 4. The viscosity number is in the range of 50 to 450 g / mL, preferably 80 to 250 g / mL (measured in o-dichlorobenzene / phenol (weight ratio 50 / 50)). The melting point is in the range of 85 to 15°C, preferably in the range of 95 to 140°C.

[0051] The MVR (melt volume rate) of polyester b1 according to EN ISO1133-1 EN (190℃, 2.16kg load) is approximately 0.5 to 20cm 3 / 10 minutes, preferably 5-15cm 3 The acid value according to DIN EN12634 is generally 0.01 to 1.2 mgKOH / g, preferably 0.01 to 1.0 mgKOH / g, and particularly preferably 0.01 to 0.7 mgKOH / g.

[0052] Generally, the at least one inorganic filler is selected from the group consisting of chalk, graphite, gypsum, conductive carbon black, iron oxide, calcium sulfate, dolomite, kaolin, silicon dioxide (quartz), sodium carbonate, calcium carbonate, titanium dioxide, silicates, wollastonite, mica, montmorillonite and talc in an amount of 0 to 25% by weight, in particular 3 to 20% by weight, based on the total weight of layer B. Preferred inorganic fillers are silica, kaolin and calcium sulfate, particularly preferred are calcium carbonate and talc.

[0053] A preferred embodiment of layer B comprises: b1) 60 to 100% by weight of an aliphatic-aromatic polyester selected from the group consisting of polybutylene adipate-co-terephthalate, polybutylene azelate-co-terephthalate and polybutylene sebacate-co-terephthalate; b2) 0 to 15% by weight, preferably 3 to 12% by weight, of a polyhydroxyalkanoate, preferably polylactic acid; b3) 0 to 25% by weight, preferably 3 to 20% by weight, of an inorganic filler.

[0054] In one embodiment, layer B does not contain any lubricant or release agent. This embodiment shows very good compatibility with layer A at layer thicknesses of up to 150 μm, which results in very good adhesion of the laminated film to substrates, such as, in particular, paper or paperboard. This is shown by the fact that fiber breakage occurs when attempting to peel the film off the paper or paperboard again.

[0055] In a further embodiment, layer B contains 0.05-0.3 wt. % of a lubricant or release agent, such as erucamide or preferably stearamide, based on the total weight of layer B. This embodiment shows very good compatibility with layer A at layer thicknesses of up to 50 μm, which results in very good adhesion of the laminated film to substrates, such as paper or paperboard in particular. This is shown by the fact that fiber breakage occurs when trying to peel the film off the paper or paperboard again. On the other hand, when a lubricant or release agent such as behenamide is used in layer B, a poor compatibility with layer A is observed.

[0056] Furthermore, the compounds of components i-v according to the invention may contain other additives known to those skilled in the art. For example, additives customary in plastics technology, such as stabilizers; nucleating agents, such as the inorganic fillers b3 already mentioned above or even crystalline polylactic acid; release agents, such as stearates (especially calcium stearate); plasticizers, such as glyceric acid esters, such as citrate esters (especially acetyl tributyl citrate), triacetyl glycerol or ethylene glycol derivatives, surfactants, such as polysorbates, palmitates or laurates; antistatic agents, UV absorbers; UV stabilizers; antifogging agents, pigments or preferably the biodegradable dye Sicoversal® from Fa.BASF SE. The additives are used in concentrations of 0 to 2% by weight, in particular 0.1 to 2% by weight, based on layer B. The plasticizers may be present in layer B according to the invention at 0.1 to 10% by weight.

[0057] Most of the foods and / or beverages in the food industry place high requirements on the oxygen or aroma barrier. Here, a layered structure with an additional barrier layer C has proven advantageous. A suitable layer structure is for example A / B / C / B, where layers A and B have the abovementioned meanings and layer C is a barrier layer made of polyglycolic acid (PGA), ethylene vinyl alcohol (EVOH) or preferably polyvinyl alcohol (PVOH).

[0058] The barrier layer C usually has a thickness of 2 to 10 μm and preferably consists of polyvinyl alcohol. A suitable PVOH is, for example, G-Polymer from Mitsubishi Chemical, in particular G-Polymer BVE8049. Since PVOH does not adhere well to the biopolymer layer B, the barrier layer is preferably composed of separate layers C' / C / C', layer C' representing an adhesion promoter layer. A suitable adhesion promoter is, for example, copolymer BTR-8002P from Mitsubishi Chemical. The adhesion promoter layer usually has a thickness of 2 to 6 μm. In this case, the laminated film has, for example, an overall layer structure of A / B / C' / C / C' / B or B'.

[0059] Another suitable layer structure is A / B / C / B', in which layers A, B and C have the abovementioned meanings and layer B' has a layer thickness of 10 to 100 μm and contains, in addition to the components mentioned for layer B, 0.2 to 0.5% by weight, based on the total weight of layer B', of erucamide, stearamide or, preferably, behenamide as lubricant or release agent.

[0060] The lamination film according to the present invention is used for composite film lamination of substrates selected from the group of biodegradable films, metal films, metallized films, cellophane or preferably paper products.

[0061] For purposes of this invention, the term "paper product" includes all types of paper and paperboard.

[0062] Fibers suitable for making the paper products include all commonly used types, such as mechanical pulp, bleached and unbleached chemical pulp, paper pulp from any annual crop and waste paper (including the form of broken paper, either coated or uncoated). The fibers may be used either alone or in any mixture thereof to make pulp from which paper products are made. For example, the term wood pulp includes groundwood pulp, thermomechanical pulp (TMP), chemi-thermomechanical pulp (CTMP), compressed wood pulp, semi-chemical pulp, high-yield chemical pulp, and refiner pulp (RMP). Exemplary chemical pulps include sulfate pulp, sulfite pulp, and soda pulp. Examples of annual plants suitable for pulp making include rice, wheat, sugarcane, and kenaf.

[0063] In each case sizing agents are usually added to the pulp in an amount of 0.01 to 3% by weight, preferably 0.05 to 1% by weight, based on the solids content of the paper dry matter, this amount varying according to the desired degree of sizing of the finished paper. The paper may also contain other substances such as starch, pigments, dyes, optical brighteners, biocides, strength agents, fixing agents, defoamers, retention agents and / or drainage aids.

[0064] The composite film produced preferably has the following structure: (i) paper having a basis weight of 30 to 600 g / m2, preferably 40 to 400 g / m2, more preferably 50 to 150 g / m2; ii) A laminate film according to the present invention having a total thickness of 5.5 to 300 μm, preferably 10 to 150 μm, particularly preferably 15 to 100 μm.

[0065] A wide variety of materials can be used for the paper layer, such as, for example, white or brown kraft liner, pulp, recycled paper, cardboard or screening.

[0066] The total thickness of the paper-film composite is usually between 31 and 1000 g / m2. Paper-film composites between 80 and 500 μm can preferably be produced by lamination, paper-film composites between 50 and 300 μm can particularly preferably be produced by extrusion coating.

[0067] In the laminated film according to the invention, the substrate (e.g. paper) is protected against mineral oils and other types of oils, as well as against grease and moisture, since the laminated film exerts a corresponding barrier effect. On the other hand, when the laminated film is used for food packaging, the food products are protected against mineral oils and inorganic substances present, for example, in waste paper, since the laminated film exerts this barrier effect. Furthermore, the laminated film can be sealed to itself, as well as to paper, cardboard, cellophane and metal, thus allowing the production of, for example, coffee cups, beverage cartons or cartons for frozen products. Particularly suitable for food and / or beverage containers are capsules, pods, pouches, cartridges, etc., preferably containing coffee and / or tea.

[0068] The composite films are particularly suitable for the manufacture of paper bags for dry foods, e.g. coffee, tea, soup powder, sauce powder; for liquids; tubular laminates; paper carrier bags, paper laminates and coextrusions for ice cream, confectionery (e.g. chocolate and cereal bars) and paper tapes; paper cups, yogurt pots; ready meal trays; packaged paperboard (cans, drums), wet strength cartons for outer packaging (wine bottles, groceries); coated paperboard fruit boxes; fast food plates; staple trays; beverage cartons, as well as cartons for liquids such as detergents and cleaning products, cartons for frozen products, ice cream packaging (e.g. ice cream cups, packaging materials), e.g. packaging materials for ice cream cups, cone-shaped ice cream cones); paper labels; flower pots and plant pots.

[0069] The composite films produced according to the present invention are particularly suitable for the production of packaging, especially food packaging.

[0070] Thus, the present invention provides the use of a laminate film as described herein in the manufacture of a composite film that is biodegradable, or preferably biodegradable under home composting conditions, the composite film being part of a home compostable flexible packaging.

[0071] An advantage of the present invention is that the laminated film used according to the present invention allows good adhesive bonding of different materials to one another, such as the substrate and layer B, and provides high strength to the bonded composite. Furthermore, the laminated films produced according to the present invention exhibit good biodegradability, in particular home compostability.

[0072] For the purposes of the present invention, the characteristic "biodegradable" is fulfilled for a substance or mixture of substances if this substance or mixture of substances has a percentage of biodegradability according to DIN EN 13432 of at least 90% after 180 days.

[0073] Generally, biodegradation results in polyesters (blends) that degrade in a reasonable and detectable time. Degradation may be enzymatic, hydrolytic, oxidative, and / or by exposure to electromagnetic radiation, such as UV radiation, and is usually mainly caused by the action of microorganisms, such as bacteria, yeasts, fungi, and algae. Biodegradability can be quantified, for example, by mixing the polyester with compost and storing it for a certain time. For example, according to DIN EN13432 (see ISO14855), CO2-free air is flowed through the mature compost during composting, which is subjected to a defined temperature program. Here, biodegradability is defined as a percentage of biodegradation by the ratio of the net CO2 release of the sample (after subtracting the CO2 release by the compost without the sample) to the maximum CO2 release of the sample (calculated from the carbon content of the sample). Biodegradable polyesters (blends) usually show clear signs of degradation, such as fungal growth, cracks, and pitting, after only a few days of composting.

[0074] Other methods for measuring biodegradability are described, for example, in ASTM D 5338 and ASTM D 6400-4.

[0075] The present invention preferably provides laminated films or laminated films including these laminated films that are biodegradable under home composting conditions (25±5° C.), meaning that the laminated film or composite film decomposes to greater than 90% by weight in CO2 and water within 360 days.

[0076] Home compostability is tested according to Australian Standard AS 5810-2010 or French Standard NFT 51-800 or ISO 14855-1(2012) "Determination of ultimate aerobic biodegradability of plastics under controlled composting conditions-Method by analysis of evolved carbon dioxide" at ambient temperature (28±2°C) to simulate home composting conditions instead of the temperature of 58°C stated in ISO Standard 14855-1(2012).

[0077] Features: The glass transition temperature was determined by differential scanning calorimetry (ASTM D 3418-08, "midpoint temperature" of the second heating curve, heating rate 20 K / min).

[0078] The melting point and enthalpy of fusion are determined according to DIN 53765 (1994) (melting point = peak temperature) by heating the polyurethane film to 120°C, followed by heating at 20 K / min and cooling at 20 K / min to 23°C and annealing there for 20 hours.

[0079] raw materials Layer A) components a-1) Epotal® Eco 3702, an aqueous polyurethane dispersion manufactured by BASF SE (see International Application No. PCT / EP2021 / 054570) a-2) Epotal® P 100eco, an aqueous polyurethane dispersion manufactured by BASF SE (see WO 2010 / 034712)

[0080] Layer B) Ingredients Ingredient b1): b1-1) Polybutylene adipate-co-terephthalate: ecoflex® F C1200 (2.5-4.5 cm) manufactured by BASF SE 3 / 10 min (190°C, 2.16 kg MVR) b1-2) Polybutylene sebacate-co-terephthalate: Ecoflex® FS C2200 (3-5 cm) manufactured by BASF SE 3 / 10min (190℃, 5kg MVR)

[0081] component b2) b2-1) Polylactic acid: (PLA) NatureWorks Ingeo® 4044 D (1.5-3.5 cm) 3 / 10 min (190°C, 2.16 kg MVR)

[0082] Ingredient b3) b3-1) Plustalc H05C made by company Elementis b3-2) Calcium carbonate made by company Omya

[0083] component b4) b4-1) Erucamide: Crodamide (trademark) ER manufactured by Croda International b4-2) Crodamide SRV, a stearic acid amide manufactured by company Croda b4-3) Crodamide BR, behenic acid amide manufactured by company Croda

[0084] component b5) b5-1) Joncryl® ADR 4468, glycidyl methacrylate manufactured by BASF SE

[0085] Layer C) Components c-1(C') Mitsubishi Chemical's BTR-8002P adhesion promoter c-2 Mitsubishi Chemical's G Polymer BVE8049 PvOH

[0086] Layer B composition The compounds listed in Table 1 were produced in a Coperion MC 40 extruder. The outlet temperature was set at 250°C. The extrudate was then pelletized in water. Following pelletization, the pellets were dried at 60°C.

[0087] [Table 1]

[0088] [Table 2] * The adhesion of the laminated film to the substrate (paper) was determined as follows.

[0089] Base film B was fixed on a laboratory coating table with the corona pre-treated side up and the adhesive to be tested was coated directly onto the film using a squeegee. Adhesive A was dried with a hot air blower for 2 minutes and then the laminated film was applied with a hand roller and pressed on a roller lamination table onto papers of different thicknesses from 50 gsm to 130 gsm at 70°C, a roller speed of 5 m / min and a lamination pressure of 6.5 bar. The laminate was then cut into 15 millimeter wide strips using a cutting template and subjected to various storage cycles. After storage, the laminated strips were pulled apart on a tensile tester and the force required to do so was recorded. The test was carried out on the tensile tester at a 90 degree angle and a pull-off speed of 100 mm / min. The test strip was split on one side where one of the loose ends was fixed in the upper clamp of the tensile tester and the other in the lower clamp and the test was started. The score (+) shown in the last column of Table 2 means that fiber breakage was observed. The score (-) in the last column means that no fiber breakage was observed.

[0090] The tests shown in Table 2 show that laminated films that do not contain the release agent b4 in the layer show very good adhesion to the base paper with a total layer thickness of the laminated film of up to about 150 μm. When erucamide b4-1 or stearamide b4-2 are used as release agents in concentrations of up to 0.3% by weight, very good adhesion to the base paper can be achieved with a total layer thickness of the laminated film of up to about 50-60 μm. On the other hand, when behenamide b4-3 is used as release agent in concentrations of 0.2-0.3% by weight, adhesion to the paper is already insufficient at a laminated film thickness of 17 μm.

[0091] Home composting test Home compostability is tested according to French standard NFT 51-800 or ISO 14855-1 (2012) "Determination of ultimate aerobic biodegradability of plastics under controlled composting conditions-Method by analysis of evolved carbon dioxide" at ambient temperature (28±2°C) to simulate home composting conditions instead of the stated temperature of 58°C.

[0092] The home compostability of about 60 μm thick laminated films of Examples 4 and 12 was investigated under the above conditions. Complete (>90%) degradation of the films was observed after 116 and 157 days, respectively. Thus, these films meet the criteria for home compostability according to Australian Standards AS 5810-2010 and ISO 14855-1 (2012). Therefore, it can be assumed that thinner films with layer structure A / B and compositions of layer B: I, V-VIII (see Table 1) are also home compostable.

Claims

1. A biodegradable laminate film having a layer structure A / B, wherein Layer A having a thickness of 0.5 to 7 μm comprises a polyurethane or acrylate adhesive, and Layer B having a thickness of 5 to 150 μm comprises an aliphatic polyester and / or an aliphatic-aromatic polyester, wherein the aliphatic-aromatic polyester is configured as follows: b1-i) 30 to 70 mol % of a C6 to C18 aliphatic dicarboxylic acids, based on components b1-i and b1-ii; b1-ii) 30 to 70 mol % of aromatic dicarboxylic acids, based on components b1-i and b1-ii; b1-iii) 98 to 100 mol % of 1,3-propanediol or 1,4-butanediol, based on components b1-i and b1-ii; b1-iv) 0 to 2 wt. % of a chain extender and / or branching agent, based on components b1-i to b1-iii.

2. Layer B is b1) 60 to 100% by weight of an aliphatic-aromatic polyester selected from the group consisting of polybutylene adipate-co-terephthalate, polybutylene azelate-co-terephthalate and polybutylene sebacate-co-terephthalate; b2) 0 to 15% by weight, preferably 3 to 12% by weight, of a polyhydroxyalkanoate, preferably polylactic acid; b3) 0 to 25% by weight, preferably 3 to 20% by weight, of inorganic fillers The laminated film according to claim 1, which comprises:

3. Layer A is formed from an aqueous polyurethane dispersion, at least 60% by weight of the polyurethane being a1) at least one diisocyanate; a2) at least one polyesterol; a3) at least one difunctional carboxylic acid selected from the group consisting of dihydroxycarboxylic acids and diaminocarboxylic acids; It consists of 3. The laminated film according to claim 1 or 2, wherein the polyurethane has a glass transition temperature of less than 20°C, or a melting point of no more than 20°C and a melting enthalpy of less than 10 J / G.

4. 3. The laminate film according to claim 1, wherein Layer B has a thickness of 10 to 50 μm and contains 0.05 to 0.3 wt. % of erucamide, or preferably stearamide, based on the total weight of Layer B.

5. 1. A biodegradable laminate film having a layer structure A / B / C / B, in which layers A and B have the meanings defined in claim 1 or 2, and layer C is a barrier layer made of polyglycolic acid, ethylene vinyl alcohol or preferably polyvinyl alcohol.

6. 6. The laminate film of claim 5, wherein the barrier layer is comprised of separate layers C' / C / C', where layer C is comprised of polyvinyl alcohol and layer C' is an adhesion promoter layer.

7. 1. A biodegradable laminate film having a layer structure A / B / C / B', wherein the layers A, B and B' have the meanings defined in claim 1 or 2, and the layer B' has a layer thickness of 10 to 100 μm and contains 0.2 to 0.5 wt. % of erucamide, stearamide or preferably behenamide, based on the total weight of the layer B'.

8. 3. Use of the laminate film according to claim 1 or 2 for composite film lamination of substrates selected from the group consisting of biodegradable films, metal films, metallized films, cellophane, or preferably paper or cardboard.

9. 3. A food and / or beverage container comprising a substrate and a biodegradable laminate film coating, wherein the biodegradable laminate film is as defined in claim 1 or 2.

10. 10. The food and / or beverage container of claim 9, wherein the substrate is paper or cardboard and the container contains a coffee or tea product therein.

11. 10. The food and / or beverage container of claim 9 configured as a capsule, pod, pouch, cartridge or the like.