Biodegradable Laminate Film

Abstract

The present invention relates to a biodegradable laminate film having an A / B layer structure, in which layer A, 0.5-7 μm thick, comprises a polyurethane or acrylate adhesive, and layer B, 5-150 μm thick, comprises an aliphatic polyester and / or an aliphatic-aromatic polyester, in which the aliphatic-aromatic polyester has the following composition: b1-i) 30-70 mol % of C6-C, based on components b1-i and b1-ii 18 dicarboxylic acids; b1-ii) 30 to 70 mol % of terephthalic acid, based on components b1-i and b1-ii; b1-iii) 98 to 100 mol % of propane-1,3-diol or butane-1,4-diol, based on components b1-i and b1-ii; b1-iv) 0 to 2 mass % of a chain extender and / or branching agent, based on components b1-i and b1-ii.

Description

[Technical field]

[0001] explanation The present invention relates to a biodegradable laminate film having an A / B layer structure, 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, in which the aliphatic-aromatic polyester has the following composition: b1-i) 30 to 70 mol% of C6 to C based on components b1-i and b1-ii 18 Dicarboxylic acids; b1-ii) 30 to 70 mol % of terephthalic acid, based on components b1-i and b1-ii; b1-iii) 98 to 100 mol% of propane-1,3-diol or butane-1,4-diol, based on components b1-i and b1-ii; b1-iv) 0 to 2% by weight of a chain extender and / or branching agent, based on components b1-i and b1-ii.

[0002] The invention further relates to the use of said laminate film for coating a substrate, in particular paper or cardboard, as well as to a process for producing a composite film, in which said laminate film is pressed onto a substrate.

[0003] Flexible packaging is used especially in the food industry. They often consist of composite films bonded together by a suitable adhesive, at least one of which is a polymeric film. There is a high demand for biodegradable composite film packaging that can be disposed of by composting after use.

[0004] Different approaches have been pursued in the literature so far: WO 2010 / 034712 describes a method for extrusion coating paper with biodegradable polymers. The coated papers obtainable by the method described in WO 2010 / 034712 are not suitable for all applications due to limited adhesion to the paper, mechanical properties, barrier properties and biodegradability of the paper composite.

[0005] WO 2012 / 013506 describes the use of aqueous polyurethane dispersion adhesives for producing composite films, some of which are industrially compostable. Decomposition in industrial composting plants takes place under high humidity, in the presence of certain microorganisms, and at a temperature of about 55° C. The requirements for flexible packaging with regard to biodegradability are constantly increasing, and home composting is now 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 mechanical and barrier properties.

[0006] It was therefore an object of the present invention to provide a laminate film which is improved in terms of biodegradability, preferably home compostable, has good adhesion to substrates, preferably paper, and also meets other requirements of modern flexible packaging.

[0007] Surprisingly, the laminate film meets these criteria.

[0008] The invention is described in further detail below.

[0009] Layer A, also called adhesive layer, forms a bond between layer B and the substrate. Layer A has a layer thickness of 0.5-7 μm and comprises a polyurethane or acrylate adhesive.

[0010] The adhesive of Layer A consists essentially of at least one polyurethane dispersed in water, preferably as a polymeric binder, and optionally additives such as fillers, thickeners, defoamers, as described in detail in WO 2012 / 013506. The essential features of the polyurethane adhesive described in WO 2012 / 013506, to which explicit reference is made, are listed below.

[0011] The polymeric binder is preferably present in the form of a dispersion in water or 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 only solvent. In the case of mass data relating to the composition of the adhesive, water or other solvents are not included in the calculation.

[0012] The polyurethane dispersion adhesive is preferably biodegradable. Biodegradability in the sense of the present application exists, 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 ISO standard 14855 (2005), after 20 days is at least 30%, preferably at least 60% or at least 80%.

[0013] The polyurethane is preferably composed mainly of polyisocyanates, in particular diisocyanates, on the one hand, and polyesterdiols and difunctional carboxylic acids as reactants on the other hand. The polyurethane is preferably composed of at least 40% by weight, particularly preferably at least 60% by weight, very particularly preferably at least 80% by weight of diisocyanates, polyesterdiols and difunctional carboxylic acids.

[0014] The polyurethane may be amorphous or semi-crystalline. If the polyurethane is semi-crystalline, the melting point is preferably below 80° C. The polyurethane preferably comprises polyester diol in an amount of more than 10% by weight, more than 50% by weight, or at least 80% by weight, based on the polyurethane. Polyurethane dispersions sold under the name Epotal® by BASF SE are particularly suitable.

[0015] Overall, the polyurethane preferably consists of: a) diisocyanates, b) a diol, b1) 10 to 100 mol % of the diol (b) is a polyester diol and has a molecular weight of 500 to 5000 g / mol, b2) 0 to 90 mol% of the diol (b) has a molecular weight of 60 to 500 g / mol, based on the total amount of the diol (b); Diol 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 have 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.

[0016] Particularly preferred is the home compostable adhesive of layer A described in PCT / EP2021 / 054570, published as WO 2021 / 175676. Essential features of the polyurethane adhesive described in PCT / EP2021 / 054570, which are expressly referenced herein, are listed below:

[0017] The aqueous polyurethane dispersion adhesive of PCT / EP2021 / 054570 is suitable for the manufacture of a composite film that is biodegradable under domestic composting conditions (25±5°C), wherein at least one layer B and a second substrate are bonded together using a polyurethane dispersion adhesive A, and wherein at least one of the substrates is a polymeric film that is biodegradable under home composting conditions, and at least 60% by weight of the polyurethane is (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 a glass transition temperature of less than 20° C. and does not have a melting point above 20° C., or has a melting point above 20° C. with a melting enthalpy of less than 10 J / g; and Preferably, the polyurethane adhesive layer A decomposes under home composting conditions to more than 90% by mass into CO2 and water within 360 days, and the polyurethane adhesive layer A is preferably home compostable, and preferably the laminate film A / B produced therefrom is biodegradable under home composting conditions if, after aerobic composting at 25±5° C. for a period of 180 days or less, a maximum of 10% of the original dry mass of the material is present in the >2 mm sieve fraction.

[0018] Preferably, the polyurethane adhesive, layer B and / or the substrate and / or the film from the composite film are home compostable.

[0019] Particularly suitable are the polyurethane dispersions sold under the name Epotal® Eco by BASF SE.

[0020] 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, where the aliphatic-aromatic polyester has the following composition: b1-i) 30 to 70 mol% of C6 to C based on components b1-i and b1-ii 18 Dicarboxylic acids; b1-ii) 30 to 70 mol % of terephthalic acid, based on components b1-i and b1-ii; b1-iii) 98 to 100 mol% of propane-1,3-diol or butane-1,4-diol, based on components b1-i and b1-ii; b1-iv) 0 to 2% by mass of a chain extender and / or branching agent based on components b1-i and b1-ii It is of the following.

[0021] Aliphatic polyesters are understood to mean, for example, the polyesters described in more detail in WO 2010 / 034711, to which explicit reference is made here.

[0022] The polyesters of (i) in WO 2010 / 034711 generally have the following structure: ia) 80-100 mol% succinic acid based on components ia-ib; ib) 0-20 mol% of one or more C6-C 20 Dicarboxylic acids; 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 mass % of a chain extender or branching agent, based on components ia to ic.

[0023] The synthesis of polyesters i of WO 2010 / 034711 preferably takes place by direct polycondensation reaction of the individual components. Dicarboxylic acid derivatives, together with diols, are directly converted to high molecular weight polycondensates in the presence of a transesterification catalyst. On the other hand, copolyesters are prepared by the reaction of polybutylene succinate (PBS) with C6-C 20 They can also be obtained by transesterification with dicarboxylic acids. As catalysts, zinc, aluminum and especially titanium catalysts are usually used. Titanium catalysts such as tetra(isopropyl)orthotitanate and especially tetraisobutoxytitanate (TBOT) are superior to tin, antimony, cobalt and lead catalysts frequently used in the literature, such as tin dioctanoate, because they leave less catalyst residues and less toxic products in the product. This fact is particularly important since biodegradable polyesters are released directly into the environment.

[0024] The polyesters mentioned can be prepared using the methods described in JP 2008-45117 and EP 488617. It has been found to be advantageous to first convert components a-c into prepolyesters having a VZ of 50-100 mL / g, preferably 60-80 mL / g, and then react this by chain extension with chain extenders i-d, such as diisocyanate- or epoxide-containing polymethacrylates, to obtain polyesters i having a VZ of 100-450 mL / g, preferably 150-300 mL / g.

[0025] The acid component ia used is 80-100 mol %, preferably 90-99 mol %, particularly preferably 92-98 mol % succinic acid, based on the acid components a and b. Succinic acid is available via petrochemical routes, preferably from renewable raw materials, as described, for example, in EP 2 185 682 A1. EP 2 185 682 A1 discloses a biotechnological process for the production of succinic acid and 1,4-butanediol starting from different carbohydrates using microorganisms of the family Pasteurellaceae.

[0026] The acid component ib is used in an amount of 0 to 20 mol %, preferably 1 to 10 mol %, particularly preferably 2 to 8 mol %, based on the acid components ia and ib.

[0027] C6~C 20 The dicarboxylic acids ib are in particular adipic acid, suberic acid, azelaic acid, sebacic acid, brassylic acid and / or C 18 Dicarboxylic acids are to be understood. Suberic acid, azelaic acid, sebacic acid and / or brassylic acid are preferred. The acids can be obtained from renewable raw materials. For example, sebacic acid can be obtained from castor oil. Such polyesters are characterized by excellent biodegradation behavior [Literature: Polym. Degr. Stab. 2004, 85, 855-863].

[0028] The dicarboxylic acids ia and ib can be used as free acids or in the form of ester-forming derivatives. The ester-forming derivatives include, 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. Anhydrides of the dicarboxylic acids can also be used. The dicarboxylic acids or their ester-forming derivatives can be used individually or as mixtures.

[0029] 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 due to its higher melting temperature and good crystallization of the copolymer formed.

[0030] Generally, at the beginning of the polymerization, the diol (component ic) is added to the acids (components ia and ib) in a diol to diacid ratio of 1.0:1 to 2.5:1, preferably 1.3:1 to 2.2:1. Excess diol is removed during the polymerization so that at the end of the polymerization an approximately equimolar ratio is reached. Approximately equimolar is understood to mean a diacid / diol ratio of 0.98 to 1.00.

[0031] In one embodiment, it comprises 0 to 1% by weight, preferably 0.1 to 0.9% by weight, particularly preferably 0.1 to 0.8% by weight, based on the total mass of components ia to ib, of branching agents id and / or chain extenders id selected from the group consisting of polyfunctional isocyanates, isocyanurates, oxazolines, carboxylic anhydrides such as maleic anhydride, epoxides (especially epoxide-containing poly(meth)acrylates), at least trifunctional alcohols or at least trifunctional carboxylic acids. As a rule, no branching agents are used, only chain extenders.

[0032] Suitable difunctional chain extenders are, for example, 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 methylenebis(4-isocyanatocyclohexane). Particularly preferred is isophorone diisocyanate, especially 1,6-hexamethylene diisocyanate.

[0033] Aliphatic polyesters are understood to mean 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). For example, the aliphatic polyesters PBS and PBSA are sold by Mitsubishi under the name BioPBS®. More recent developments are described in WO 2010 / 034711.

[0034] The polyesters i generally have a number-average molecular weight (Mn) in the range of 5000 to 100000, 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, preferably 60000 to 200000 g / mol, and an Mw / Mn ratio of 1 to 6, preferably 2 to 4. The viscosity number is 30 to 450, 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).

[0035] Among the aliphatic polyesters of layer B, polyhydroxyalkanoates are used, such as polycaprolactone (PCL), 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)), in particular polylactic acid (PLA).

[0036] It is preferable to use polylactic acid b2 having the following property profile: Melt volume velocity (MVR at 190°C and 2.16 kg according to ISO1133-1DE, 0.5-100, especially 5-50 cm 3 / 10 minutes) Melting point: below 240℃ Glass transition temperature (Tg) above 55℃ Moisture content less than 1000ppm Residual monomer content (lactide) less than 0.3% Molecular weight over 80,000 daltons.

[0037] Preferred polylactic acids are crystalline polylactic acid types from NatureWorks, such as Ingeo® 6201D, 6202D, 6251D, 3051D and 3251D, in particular 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. However, amorphous types of polylactic acid, such as Ingeo® 4060D from NatureWorks, are also suitable.

[0038] Aliphatic-aromatic polyesters b1 in layer B should be understood to mean linear, chain-extended and optionally branched and chain-extended polyesters, as described, for example, in WO 96 / 15173-15176 or WO 98 / 12242, which are incorporated herein by reference. Mixtures of different partially aromatic polyesters are useful as well. Interesting recent developments are based on renewable raw materials (see WO 2010 / 034689). In particular, polyesters b1 are products such as ecoflex® (BASF SE).

[0039] Preferred polyesters b1 include polyesters which contain as essential components: b1-i) 30 to 70 mol %, preferably 40 to 60 mol %, particularly preferably 50 to 60 mol %, based on components b1-i) and b1-ii), of aliphatic dicarboxylic acids or mixtures thereof, preferably adipic acid, in particular azelaic acid, sebacic acid and brassylic acid. b1-ii) 30 to 70 mol %, preferably 40 to 60 mol %, particularly preferably 40 to 50 mol %, based on the components b1-i) and b1-ii), of aromatic dicarboxylic acids or mixtures thereof, preferably 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% by weight, preferably 0.1 to 1% by weight, based on the 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, in particular glycerol.

[0040] Suitable aliphatic diacids and corresponding derivatives b1-i are generally those having 6 to 18 carbon atoms, preferably 9 to 14 carbon atoms. They may be linear or branched.

[0041] Examples include 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 thereof.

[0042] It is preferable to use adipic acid, azelaic acid, sebacic acid, brassylic acid or their respective ester-forming derivatives or mixtures thereof. It is particularly preferable to use azelaic acid or sebacic acid or their respective ester-forming derivatives or mixtures thereof.

[0043] The following aliphatic aromatic polyesters are particularly 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.

[0044] 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) and mixtures of polybutylene adipate-co-terephthalate (PBAT) with polybutylene azelate-co-terephthalate (PBAzT) and polybutylene sebacate-co-terephthalate (PBSeT) due to their improved suitability for home composting in accordance with Australian Standards AS 5810-2010 and ISO 14855-1 (2012).

[0045] The aromatic dicarboxylic acids or their ester-forming derivatives b1-ii can be used alone or in a mixture of two or more. It is particularly preferred to use ester-forming derivatives such as terephthalic acid or dimethyl terephthalate.

[0046] The diols b1-iii, 1,4-butanediol and 1,3-propanediol, are available as renewable raw materials. Mixtures of the mentioned diols can also be used.

[0047] In general, 0 to 1% by weight, preferably 0.1 to 1.0% by weight, particularly preferably 0.1 to 0.3% by weight, of a branching agent, based on the total weight of the polyester, and / or 0 to 1% by weight, preferably 0.1 to 1.0% by weight, of a chain extender (b1-vi), based on the total weight of the polyester, is used. The chain extenders used are preferably di- or polyfunctional isocyanates, preferably hexamethylene diisocyanate, and the branching agents used are preferably polyols, such as trimethylolpropane, pentaerythritol, in particular glycerol.

[0048] The polyester b1 generally has a number average molecular weight (Mn) in the range of 5000 to 100000, in particular in the range of 10000 to 75000 g / mol, preferably in the range of 15000 to 38000 g / mol, a mass average molecular weight (Mw) of 30000 to 300000, preferably 60000 to 200000 g / mol, and an Mw / Mn ratio of 1 to 6, preferably 2 to 4. The viscosity number is 50 to 450, preferably 80 to 250 g / mL (measured with o-dichlorobenzene / phenol (mass ratio 50 / 50)). The melting point is in the range of 85 to 150 ° C, preferably in the range of 95 to 140 ° C.

[0049] The MVR (melt volume rate) (190°C, 2.16 kg mass) of polyester b1 according to EN ISO 1133-1 DE is generally 0.5 to 20, preferably 5 to 15 cm 3 The acid number according to DIN EN 12634 is generally 0.01 to 1.2 mg KOH / g, preferably 0.01 to 1.0 mg KOH / g, particularly preferably 0.01 to 0.7 mg KOH / g.

[0050] Typically, 0 to 25% by weight, in particular 3 to 20% by weight, of at least one inorganic filler b3 is used, based on the total weight of layer B, selected from the group consisting of chalk, graphite, gypsum, carbon black, iron oxide, calcium sulfate, dolomite, kaolin, silicon dioxide (quartz), sodium carbonate, calcium carbonate, titanium dioxide, silicates, wollastonite, mica, montmorillonite, talc. Preferred inorganic fillers are silicon dioxide, kaolin and calcium sulfate, particularly preferred are calcium carbonate and talc.

[0051] A preferred embodiment of layer B comprises: b1) 60 to 100% by mass, preferably 60 to 99.95% by mass, 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 polyhydroxyalkanoates, preferably polylactic acid; b3) 0 to 25% by weight, preferably 3 to 20% by weight, of an inorganic filler.

[0052] Layer B particularly preferably further comprises b4) 0.05 to 0.3 mass % of a lubricant selected from erucamide and stearamide Includes.

[0053] In one embodiment, layer B does not contain any lubricant or release agent. This embodiment has very good compatibility with layer A up to a layer thickness of 150 μm, which results in very good adhesion of the laminate film to substrates such as paper or cardboard. This means that when trying to peel the film from the paper or cardboard, fiber breakage occurs.

[0054] In a further embodiment, layer B contains 0.05-0.3% by weight of a lubricant or release agent, such as erucamide or preferably stearamide, relative to the total weight of layer B. The lubricant or release agent, especially in combination with an antiblocking agent, can be used to prevent blocking during unrolling of the polyester film and for lamination in further steps. This laminate has a layer containing polyester, which can be deformed later if necessary. This embodiment has a very good compatibility with layer A up to a layer thickness of 50 μm, and up to 80 μm in the case of stearamide, resulting in very good adhesion of the laminate film to substrates such as paper or cardboard. This is evident from the fiber breakage that occurs when trying to peel the film from the paper or cardboard. However, when lubricants or release agents such as behenamide, erucamide, stearamide are used in layer B at a concentration of more than 0.3% by weight, it is observed that they are insufficiently compatible with layer A. When Layer B contains stearamide, Layer B has a thickness of preferably 5 to 50 μm, preferably 10 to 50 μm. When Layer B contains erucamide, the thickness of the layer is preferably in the range of 5 to 80 μm, more preferably in the range of 5 to 50 μm, and particularly preferably in the range of 10 to 50 μm.

[0055] Furthermore, the compounds of components i-v according to the invention may contain other additives known to those skilled in the art, such as additives like stabilizers commonly used in the plastics industry; nucleating agents like the inorganic filler b3 or crystalline polylactic acid; anti-caking agents like stearates (especially calcium stearate); plasticizers like citrate esters (especially acetyl tributyl citrate); surfactants like glycerate esters like triacetyl glycerol or ethylene glycol derivatives, polysorbates, palmitates or laurates; antistatic agents, UV absorbers; UV stabilizers; anti-fog agents, pigments or preferably biodegradable dyes, such as Sicoversal® from BASF SE. The additives are used in concentrations of 0-2% by weight, in particular 0.1-2% by weight, relative to layer B. The plasticizers may be contained in layer B according to the invention in amounts of 0.1-10% by weight.

[0056] For flexible packaging in the food industry there are high demands on oxygen and aroma barrier. A layer structure with an additional barrier layer C has proven advantageous here. A suitable layer structure is for example A / B / C / B, where layers A and B have the abovementioned meanings and layer C represents a barrier layer made of polyglycolic acid (PGA), ethylene vinyl alcohol (EVOH) or preferably polyvinyl alcohol (PVOH).

[0057] The oxygen barrier layer C usually has a layer 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 individual layers C' / C / C', where layer C' represents an adhesion promoter. As an adhesion promoter, for example, copolymer BTR-8002P from Mitsubishi Chemical is suitable. The layer thickness of the adhesion promoter layer is usually 2 to 6 μm. In these cases, the entire laminate film has, for example, a layer structure of A / B / C' / C / C' / B or B'.

[0058] A further 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, in addition to the components described for layer B, contains 0.1 to 0.5% by weight, preferably 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.

[0059] The laminate film according to the invention is used for lamination of a composite film with a substrate selected from the group consisting of biodegradable films, metal foils, metallized films, cellophane or preferably paper products.

[0060] For purposes of this invention, the term "paper products" includes all types of paper and cardboard.

[0061] Suitable fibres for the manufacture of said paper products are all types commonly used, such as mechanical pulp, bleached and unbleached chemical pulp, paper pulp from all annual plants and waste paper (in the form of scrap, either coated or uncoated). The fibres can be used alone or in their mixtures to produce the pulp that is the raw material for the paper products. The term mechanical pulp includes, for example, wood pulp, thermomechanical pulp (TMP), chemi-thermo-mechanical pulp (CTMP), compressed wood pulp, semi-chemical pulp, high-yield chemical pulp and refiner mechanical pulp (RMP). Examples of suitable chemical pulps include sulphate pulp, sulphite pulp and soda pulp. Examples of suitable annual plants for the manufacture of paper pulp are rice, wheat, sugarcane and kenaf.

[0062] Size is 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 pulp, depending on the desired degree of sizing of the finished paper. The paper may contain other substances such as starch, pigments, dyes, optical brighteners, biocides, strength agents, fixing agents, defoamers, retention agents and / or drainage aids.

[0063] The composite film produced preferably has the following structure: i) Basis weight 30~600g / m 2 , preferably 40 to 400 g / m 2 , particularly preferably 50 to 150 g / m 2 Paper, ii) A laminate film according to the invention having a total thickness of 5.5 to 300 μm, preferably 10 to 150 μm, particularly preferably 15 to 100 μm.

[0064] For the paper layer, a variety of materials can be used, such as white or brown kraft liner, cellulose, recycled paper, cardboard, and screen.

[0065] The total thickness of the paper-film composite is usually 31 to 1000 g / m 2Preferably, a paper-film composite having a thickness of 80 to 500 μm can be produced by lamination processing, and particularly preferably, a paper-film composite having a thickness of 50 to 300 μm can be produced by extrusion coating.

[0066] The production of a composite film from the laminate film and the substrate according to the invention is preferably carried out in several steps: first, preferably i) the surface of layer B is activated by corona treatment, ii) an aqueous dispersion of polyurethane adhesive is applied and dried, and iii) the obtained laminate film of claims 1 to 7 is pressed onto the substrate with side A using an appropriate roller pressure.

[0067] Surface treatment of layer B before coating with polymer dispersion A is not necessarily required. However, better results are obtained if the surface of layer B is modified before the coating process. Conventional surface treatments, such as corona treatment, can be used here to enhance the adhesive effect. Corona treatment or other surface treatments are carried out to the extent necessary to obtain sufficient wetting with the coating composition. For this purpose, a corona treatment of about 10 watts per square meter per minute is usually sufficient. Alternatively or additionally, a primer or intermediate layer can also be used between layer B and adhesive coating A. As mentioned, the composite film, in particular the laminate film, may comprise other additional functional layers, such as a barrier layer, a printing layer, a colored layer or a lacquer layer or a protective layer. The location of the functional layer may preferably be on the outside, i.e. on the side of layer B opposite to the side on which the adhesive is applied.

[0068] In the composite film according to the invention, the substrate (e.g. paper) has protection from mineral oils and other types of oils, as well as grease and moisture, since the laminate film exerts a corresponding barrier effect. On the other hand, when the laminate film is used for food packaging, the food is protected from mineral oils and mineral substances present, for example, in waste paper, since the laminate film exerts this barrier effect. The laminate film can be welded not only to paper, cardboard, cellophane and metal, but also to itself, so that it can be used, for example, for the manufacture of coffee cups, cartons for beverages, cartons for frozen products.

[0069] The composite films are particularly suitable for the production of paper bags for dry foods, e.g. coffee, tea, powdered soups, powdered sauces; liquids, e.g. cosmetics, detergents, beverages; tubular laminates; paper carrier bags, paper laminates and coextrusions for ice cream, confectionery (e.g. chocolate and muesli bars) and paper adhesive tapes; paper cups, yogurt cups; ready meal plates; wrapped cardboard packaging (cans, drums), moisture-resistant boxes for outer packaging (wine bottles, food or beverage products); fruit boxes made of coated board; fast food plates; clamshell boxes; cartons for beverages and liquids (laundry and cleaning products, etc.), boxes for frozen products, ice cream packaging (ice cream cups, packaging, etc.), e.g. ice cream cups, packaging for cone-shaped ice waffles); paper labels; flower pots and flower pots.

[0070] It may be advantageous to apply the laminating film to the substrate using an extrusion coating process. As an intermediate layer, the aqueous laminating adhesive (polymer dispersion A) is applied. The advantage of using a laminating adhesive in an extrusion coating process is that the extrusion temperature can be reduced. The use of mild conditions saves energy and prevents the degradation of biodegradable polymers, preferably home compostable polymers.

[0071] Dispersion coatings do not need to be heated before application. The application technology is comparable to hot melt adhesives for sheet coating. Application speeds are very fast, up to 3000 m / min. The dispersion coating process can therefore be carried out in-line on the paper machine.

[0072] In the case of thin layers, it is also possible to apply layer A in the form of a hot melt as a special case of the extrusion coating process or dispersion application process. This process is described by Ullmann, TSE Troller Coating. The hot melt adhesive is pumped from a storage container preheated to about 150-200 ° C into a nozzle, from which the material is applied to the surface.

[0073] The composite films produced according to the present invention are particularly suitable for the production of flexible packaging, especially food packaging.

[0074] Thus, the present invention provides the use of a laminate film as described herein for producing a composite film that is biodegradable, or preferably biodegradable under home composting conditions, wherein the composite film is part of a home compostable flexible packaging.

[0075] An advantage of the present invention is that the laminate film used according to the present invention allows for good adhesive bonding between different materials such as the substrate and layer B, imparting a high level of strength to the bonded composite material. The composite films produced according to the present invention also have good biodegradability, in particular home compostability.

[0076] For the purposes of the present invention, the characteristic "biodegradable" for a substance or mixture of substances is fulfilled if this substance or mixture of substances has a degree of biodegradability according to DIN EN 13432 of at least 90% after 180 days.

[0077] In general, biodegradability means that the polyester (mixture) is broken down within a reasonable detectable period of time. Degradation occurs enzymatically, hydrolytically, oxidatively and / or by the action of electromagnetic radiation, e.g. UV light, 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 period of time. For example, according to DIN EN 13432 (see ISO 14855), CO2-free air flows through the mature compost during composting and it is exposed to a defined temperature program. Here, biodegradability is defined 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). The percentage of biodegradation is defined. Biodegradable polyesters (mixtures) usually show clear signs of degradation, like fungal growth, cracks and hole formation, after only a few days of composting.

[0078] Other methods for measuring biodegradability are described, for example, in ASTM D 5338 and ASTM D 6400-4.

[0079] The present invention provides a laminate film or a composite film containing these laminate films that is preferably biodegradable under home composting conditions (25±5° C.), which means that the laminate film or composite film is decomposed to 90% by mass or more in CO2 and water within 360 days.

[0080] Home composting suitability is tested according to Australian Standard AS 5810-2010 or French Standard NF T 51-800 or ISO 14855-1(2012) "Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions - Method by analysis of evolved carbon dioxide" at ambient temperature (28 ± 2 °C), simulating home composting conditions rather than the temperature of 58 °C as stated in ISO Standard 14855-1(2012).

[0081] Features: The glass transition temperature was measured using differential scanning calorimetry (ASTM D 3418-08, "midpoint temperature" of the second heating curve, heating rate 20 K / min).

[0082] 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, then heating at 20 K / min and cooling at 20 K / min to 23°C and heat-treating there for 20 hours.

[0083] Starting materials Layer A Ingredients) a-1) Epotal® Eco 3702, an aqueous polyurethane dispersion, manufactured by BASF SE (see PCT / EP2021 / 054570) a-2) Epotal® P100eco, an aqueous polyurethane dispersion from BASF SE (see WO 2010 / 034712).

[0084] Layer B) Ingredients Ingredient b1): b1-1) Polybutylene adipate terephthalate: Ecoflex® F C1200 (2.5-4.5 cm) manufactured by BASF SE 3 / 10min MVR (190℃, 2.16kg) b1-2) Polybutylene sebacate terephthalate: Ecoflex (registered trademark) FS C2200 (3-5 cm) manufactured by BASF SE 3 / 10min MVR (190℃, 5kg) component b2) b2-1) Polylactic acid: NatureWorks (PLA) Ingeo (registered trademark) 4044 D (1.5 to 3.5 cm 3 / 10min MVR (190℃, 2.16kg) Ingredient b3) b3-1) Elementis Plustalc H05C b3-2) Calcium carbonate manufactured by Omya component b4) b4-1) Erucic acid amide: Crodamide manufactured by Croda International Plc TM ER b4-2) Stearamide: Crodamide SRV manufactured by Croda b4-3) Behenamide: Crodamide BR manufactured by Croda component b5) b5-1) Joncryl® ADR 4468, glycidyl methacrylate manufactured by BASF SE.

[0085] C) Layer components c-1(C') Mitsubishi Chemical BTR-8002P adhesion promoter c-2 G Polymer BVE8049 PvOH manufactured by Mitsubishi Chemical Corporation.

[0086] Layer B composition The compounds shown in Table 1 were produced in a Coperion MC 40 extruder. The outlet temperature was set at 250° C. The extrudate was then granulated in water. After granulation, the granules were dried at 60° C.

[0087] Description of blown film plant for film production: The blown film plant consisted of a single screw extruder with a diameter of 30 mm and a length of 25 D, a spiral mandrel distributor with a diameter of 80 mm and a die gap of 0.8 mm. The expansion ratio was typically 3.5 and the width of the film tube was approximately 440 mm.

[0088] The multi-layer films were produced by coextrusion.

[0089] [Table 1]

[0090] In Tables 1 and 2, V means a comparative example.

[0091] [Table 2]

[0092] *The adhesion of the laminate film to the substrate (paper) was measured as follows: Base film B was fixed on a laboratory coating table with the corona treated side facing up and the adhesive to be tested was applied directly to the film with a knife. After drying adhesive A with a hot air blower for 2 minutes, the laminate film was applied with a hand roller and pressed in a roller laminating station to papers with thicknesses of 50 gsm to 130 gsm at 70°C, roller speed of 5 m / min and laminating pressure of 6.5 bar. The laminate was then cut into strips of width 15 mm using a cutting die and subjected to various storage cycles. After storage, the laminate strips were pulled apart in a tensile tester and the force required was recorded. Testing was performed using a tensile tester at an angle of 90 degrees and a peel speed of 100 mm / min. One side of the test strip was cut open and one of the loose ends was clamped in the upper clamp of the tensile tester and the other in the lower clamp, and the test was started.

[0093] The rating (+) shown in the last column of Table 2 means: fiber pull-out with a force of >0.6 N / 15 mm.

[0094] The rating (-) shown in the last column means: no fiber pull-out with a force of >0.6N / 15mm.

[0095] From the tests shown in Table 2, it can be seen that the laminate film without the release agent B4 in the layer shows very good adhesion to the paper substrate up to a total layer thickness of the laminate film of about 150 μm. When erucamide B4-1 or stearamide B4-2 are used as release agents up to a concentration of 0.3% by mass, very good adhesion to the paper substrate is obtained up to a total layer thickness of the laminate film of about 50-60 μm. On the other hand, when behenamide B4-3 is used as release agent at a concentration of 0.2-0.3% by mass or stearic acid at a concentration of 0.4% by mass, the adhesion to paper is already insufficient when the thickness of the laminate film is 10-17 μm.

[0096] Home composting test Home composting suitability is tested according to French standard NF T 51-800 or ISO 14855-1 (2012) "Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions - Method by analysis of evolved carbon dioxide" at ambient temperature (28 ± 2 °C), simulating home composting conditions, rather than the stated temperature of 58 °C.

[0097] The home compostability of the laminated films of Examples 4 and 12, approximately 60 μm thick, was tested under the above conditions, and 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 is believed that thin films with layer structure A / B and layer B compositions: I, V-XI (see Table 1) can also be home composted.

Claims

1. A biodegradable laminate film having an A / B layer structure, wherein Layer A having a thickness of 0.5 to 7 μm comprises a polyurethane or acrylate adhesive, and Layer B comprises an aliphatic polyester and / or an aliphatic-aromatic polyester and 0.05% to 0.3% by weight of a lubricant selected from erucamide and stearamide, wherein the aliphatic-aromatic polyester has the following composition: b1-i) 30 to 70 mol% of aliphatic C relative to components b1-i and b1-ii 6 ~C 18 dicarboxylic acids; 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% by weight of a chain extender and / or branching agent, based on components b1-i to b1-iii and the layer B containing erucamide has a layer thickness of 5 to 80 μm, and A biodegradable laminate film, wherein Layer B containing stearic acid amide has a layer thickness of 5 to 50 μm.

2. Layer B is b1) 60 to 99.95% by weight of an aliphatic-aromatic polyester selected from the group consisting of polybutylene adipate coterephthalate, polybutylene azelate coterephthalate, polybutylene sebacate coterephthalate; b2) 0 to 15% by weight, preferably 3 to 12% by weight, of polyhydroxyalkanoates, preferably polylactic acid; b3) 0 to 25% by weight, preferably 3 to 20% by weight, of inorganic fillers b4) 0.05 to 0.3% by weight of a lubricant selected from erucamide and stearamide The laminate film of claim 1 , comprising:

3. Layer A is formed from an aqueous polyurethane dispersion, wherein at least 60% by weight of the polyurethane is: 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; 2. The laminate film of claim 1, wherein the polyurethane has a glass transition temperature of less than 20°C or a melting point of less than 20°C and a melting enthalpy of less than 10 J / g.

4. 2. 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% by weight of erucamide, based on the total weight of Layer B.

5. 1. A biodegradable laminate film having an A / B / C / B layer structure, wherein layers A and B have the definitions set forth in claim 1, and layer C is an oxygen or aroma 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 composed of individual layers C' / C / C', layer C consisting of polyvinyl alcohol and layer C' being an adhesion promoter layer.

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

8. 8. Use of a laminate film according to any one of claims 1 to 7 for composite film lamination of substrates selected from the group consisting of biodegradable films, metal foils, metallized foils, cellophane, or preferably paper or cardboard.

9. 10. A method for producing a composite film, comprising: i) activating the surface of layer B by corona treatment; ii) applying an aqueous dispersion of polyurethane adhesive to the surface and drying; and iii) pressing the resulting laminate film according to any one of claims 1 to 7 onto a substrate having side A by suitable rolling pressure.