DE202010005911U1 - Fully biodegradable multilayer film - Google Patents

Abstract

A completely biodegradable multilayer film comprising (a) at least one completely biodegradable adhesion promoter layer (a) based on at least one functionalized, completely biodegradable polymer and (b) at least one preferably internal, completely biodegradable barrier layer (b).

Description

The present invention relates to a fully biodegradable primer layer (a) based on at least one functionalized fully biodegradable polymer, furthermore a fully biodegradable multilayer film comprising such a primer layer (a) and a fully biodegradable barrier layer as well as packaging made from this multilayer film, preferably are completely biodegradable.

Many packaging of packaging goods, such as foodstuffs, are generally made of thermoplastics such as polyolefins, polyesters or polyamides. In these packages, the packaged goods are usually well protected from interacting with the environment, in particular by preventing the entry of microbes and, moreover, the packages have a barrier effect to oxygen. The disadvantage is that packaging made of these plastics are not completely biodegradable.

However, it is desirable from both an ecological and economic point of view, that such packages are made of fully biodegradable materials in order to ensure a final disposal of such packaging z. B. to ensure by composting.

In the prior art, packages of multilayer films are already known which, in addition to biodegradable film layers, also have film layers which are not completely biodegradable. As a result, the entire multilayer film or the packaging produced from such a multilayer film is not complete, but only partially biodegradable. This is often due to the fact that no fully biodegradable adhesion promoters are available, but adhesion promoter layers are necessary for the construction of the multilayer films.

So are off WO 2007/135037 Packaging of multilayer films is known in which the adhesion between individual biodegradable film layers is achieved by incompletely biodegradable primer layers based on ethylene-acrylic ester copolymers. A corresponding packaging is therefore not completely biodegradable.

There is therefore a need for fully biodegradable adhesion promoters or adhesion promoter layers. In particular, there is a need for fully biodegradable multilayer films comprising at least one such fully biodegradable primer layer, as well as packages of such a fully biodegradable multi-layer film.

The object of the present invention was therefore to provide a fully biodegradable primer layer, which consists of at least one completely biodegradable plastic material, preferably as part of a fully biodegradable multi-layer film or a corresponding packaging for a wide variety of goods.

This object is achieved by providing a fully biodegradable primer layer (a) based on at least one functionalized, fully biodegradable polymer.

Another object of the present invention is to provide a fully biodegradable multilayer film comprising at least one fully biodegradable adhesive layer (a) based on at least one functionalized fully biodegradable polymer and at least one fully biodegradable barrier layer and the provision of a package of such a multilayer film.

For the purposes of this invention, the term "completely biodegradable" is understood to mean that a material, a plastic material, a single-layer or multilayer film or a layer of a multilayer film under the action of microorganisms and / or enzymes to form water, carbon dioxide and biomass DIN EN 13432 is decomposable and in the disintegration test in the context of aerobic composting after 12 weeks, a biological degradation of at least 90%, preferably at least 95%, particularly preferably ≥ 99% is achieved.

For the preparation of a primer layer (a) according to the invention, functionalized, completely biodegradable polymers are suitable.

Preferably, the adhesion promoter layer (a) according to the invention is based on at least one completely biodegradable polymer which has at least one class of functional groups selected from the group consisting of epoxide groups, peroxide groups, hydroxyl groups, amine groups, amide groups, carboxyl Groups (acid groups) and acid anhydride groups, preferably cyclic acid anhydride groups, is functionalized. Particularly preferred are completely biodegradable polymers which are functionalized with acid groups, preferably carboxylic acid groups and / or carboxylic anhydride groups, most preferably with cyclic carboxylic anhydride groups such as maleic anhydride groups.

The degree of functionalization is preferably 0.05 to 30 mol%, particularly preferably 0.1 to 5 mol%, very particularly preferably 0.1 to 2 mol%. The functionalization can be carried out, for example, by polymer-analogous reactions or by free-radical polymerization by covalent linkage (grafting) on the completely biodegradable polymers. Fully biodegradable polymers prepared by polycondensation may already have a functionalization in the course of the polycondensation.

Fully biodegradable polymers in the context of this invention are natural, preferably renewable, or semi-synthetic or synthetic polymers.

The adhesion promoter layer (a) according to the invention is preferably based on at least one fully biodegradable polymer functionalized with at least one class of the abovementioned groups selected from the group comprising lactic acid homopolymers and copolymers, preferably polylactides, particularly preferably based on DL-lactide, L-lactide and / or D-lactide, polyhydroxyalkanoates, cellulose, cellulose derivatives, (thermoplastic) starch, polyesters, polyethers, polyols and copolymers of at least two monomers of said polymers, wherein each of these aforementioned fully biodegradable polymers is functionalized.

Suitable polyesters for producing the adhesion promoter layer (a) according to the invention are at least one functionalized, fully biodegradable polyester selected from the group comprising functionalized, thermoplastic, aliphatic and partially aromatic polyesters or corresponding copolymers of polyester and further functionalized, completely biodegradable polymers, preferably lactic acid Homo- or copolymers. The functionalized polyesters used in the invention may be selected from polyols, preferably from diols such as. As ethylene glycol or 1,4-butanediol and dicarboxylic acids such as adipic acid, terephthalic acid or isoterephthalic acid. Furthermore, the functionalized polyesters of lactones having 4-10 carbon atoms such as. B. caprolactone can be produced. Functionalized polycaprolactones, functionalized polyesters and functionalized copolymers of polyester and further functionalized, completely biodegradable polymers such as. B. the market-leading products Ecoflex ^® or Ecovio ^® BASF AG.

The adhesion promoter layer (a) according to the invention is preferably based only on at least one functionalized, completely biodegradable polymer selected from the group comprising lactic acid homopolymers or copolymers, preferably polylactides, in particular based on DL-lactide, L-lactide and / or D-lactide, wherein each of said fully biodegradable polymers is functionalized with at least one class of the above-mentioned functional groups.

The adhesion promoter layer (a) according to the invention may contain as further polymer component at least one non-functionalized, completely biodegradable polymer selected from the group comprising lactic acid homopolymers and copolymers, preferably polylactides, particularly preferably based on DL-lactide, L-lactide and / or D-lactide, polyhydroxyalkanoates, cellulose, cellulose derivatives, (thermoplastic) starch, polyesters, preferably polycaprolactones, polyethers and copolymers of at least two monomers of said polymers.

As this further polymer component is preferably at least one fully biodegradable polyester, more preferably a thermoplastic, aliphatic or partially aromatic polyester or at least one corresponding co-polymer of at least one polyester and at least one further fully biodegradable polymer, preferably lactic acid Homo - or copolymers. Polyesters can be made from polyols, preferably from diols such. As ethylene glycol or 1,4-butanediol and dicarboxylic acids such as adipic acid, terephthalic acid or isoterephthalic acid. Furthermore, suitable polyesters of lactones having 4-10 carbon atoms such as. B. derived caprolactone. According to the invention preferably used as a further polymer component completely biological degradable polyesters are polycaprolactones, polyesters and co-polymers of polyester and other fully biodegradable polymers such. B. the market-leading products Ecoflex ^® or Ecovio ^® BASF AG.

The adhesion promoter layer (a) according to the invention may particularly preferably comprise as further polymer component at least one unfunctionalized, completely biodegradable polymer selected from the group comprising polylactides, preferably based on DL-lactide, L-lactide and / or D-lactide, and polyesters ,

In a preferred embodiment, the adhesion promoter layer (a) of the invention from 0.1 to 50 wt .-%, preferably 1 to 40 wt .-%, particularly preferably 5 to 30 wt .-%, based on the total weight of the primer layer (A), of at least one of said, non-functionalized, fully biodegradable polymers and of up to 50 wt .-%, preferably up to 60 wt .-%, particularly preferably up to 70 wt .-%, based on the total weight the adhesion promoter layer (a), consist of at least one functionalized, fully biodegradable polymer.

In a very particularly preferred embodiment, the adhesion promoter layer (a) according to the invention contains no further polymer component based on a non-functionalized, completely biodegradable polymer, but consists only of at least one of said, functionalized, completely biodegradable polymers.

The melt index (or melt flow index, MFI) of the adhesion promoter layer (a) according to the invention is preferably in the range from 0.2 to 100 g / 10 min, preferably from 0.5 to 30 g / 10 min, particularly preferably from 1 to 20 g / 10 min (at 190 ° C and 2.16 kg, determined after ISO 1133 ).

The adhesion promoter layer (a) according to the invention preferably has a layer thickness of ≦ 30 μm, particularly preferably ≦ 20 μm, very particularly preferably from 1 μm to ≦ 15 μm.

The completely biodegradable multilayer film according to the invention comprises, in addition to at least one completely biodegradable adhesion promoter layer (a), also a completely biodegradable barrier layer.

The multilayer film according to the invention preferably comprises at least one interior, completely degradable barrier layer (b), particularly preferably a gas barrier layer, preferably an oxygen barrier layer, a water vapor barrier layer, an oil barrier layer or a barrier layer against fragrances and / or flavors, which is made from at least one completely biodegradable polymer ,

The barrier layer (b) of the multilayer film according to the invention is preferably based on at least one completely biodegradable polymer selected from the group comprising at least partially hydrolyzed polyvinyl acetates which has a saponification degree of at least 50 mol%, preferably at least 75 mol%, particularly preferably at least 85 mol % and ethylene-vinyl alcohol copolymers (EVOH) which have an ethylene content of at most 20 mol%, preferably at most 10 mol%.

Such at least partially saponified fully biodegradable polyvinyl acetates suitable for the barrier layer (b) of the multilayer film according to the invention are obtained by complete or incomplete hydrolysis of corresponding polyvinyl acetates (PVAc) and thus comprise both partially hydrolyzed polyvinyl acetates having a saponification degree of from 50 to 98 mol%, as well as vollverseifte Polyvinylacetate (polyvinyl alcohols, PVOH) with a degree of saponification ≥ 98%. Optionally, the at least partially saponified polyvinyl alcohols in different modifications, for. B. be used in an amorphous state.

The barrier layer (b) of the multilayer film of the invention may also be preferably based on at least one fully biodegradable ethylene-vinyl alcohol copolymer (EVOH) obtained by complete or incomplete hydrolysis of ethylene-vinyl acetate copolymers (EVAc). Fully saponified ethylene-vinyl alcohol copolymers (EVOH) with a saponification degree ≥ 98% and an ethylene content of 0.01-20 mol%, preferably of 0.1-10 mol%, are particularly suitable.

In a preferred embodiment, the barrier layer (b) of the multilayer film according to the invention may contain, as further polymer component, at least one lactic acid homo- or copolymer, preferably at least one polylactide, particularly preferably based on DL-lactide, L-lactide and / or D-lactide.

The barrier layer (b) of the multilayer film according to the invention preferably consists of 0.1 to 50% by weight, preferably 1 to 40% by weight, particularly preferably 5 to 30% by weight, based on the total weight of the layer ( b), of at least one fully biodegradable lactic acid homo- or copolymers as further polymer component and the balance of at least one of the listed ethylene-vinyl alcohol copolymers (EVOH), at least one polyvinyl alcohol (PVOH), and / or at least one corresponding at least partially saponified polyvinyl acetate.

In a particularly preferred embodiment, the barrier layer (b) of the multilayer film of the invention contains no lactic acid homo- or copolymer component, but consists of a fully saponified polyvinyl acetate and / or fully saponified ethylene vinyl acetate having an ethylene content of at most 10 mol%.

The barrier layer (b) of the multilayer film according to the invention preferably has a layer thickness of from 1 μm to 300 μm, particularly preferably from 2 μm to 200 μm, very particularly preferably from 3 μm to 100 μm, particularly preferably from 4 μm to 40.

The multilayer film according to the invention preferably comprises at least one further layer (c) based on at least one completely biodegradable polymer.

This layer (c) of the multilayer film according to the invention is preferably based on at least one completely biodegradable polymer selected from the group comprising lactic acid homo- and copolymers, polyhydroxyalkanoates, cellulose, cellulose derivatives, (thermoplastic) starch, polyesters, preferably polycaprolactones, polyethers, polyols , Polyesters, preferably synthetic polyesters and copolymers of at least two monomers of said polymers.

If the layer (c) of the multilayer film according to the invention is based on at least one polyester, it is preferable to use a non-functionalized polyester described above, preferably synthetic polyester, which is also used to prepare the adhesion promoter layer (a) according to the invention.

Particularly preferably suitable polymers on which the layer (c) of the multilayer film according to the invention is based is at least one completely biodegradable polymer selected from the group comprising lactic acid homopolymers and copolymers, preferably polylactides, particularly preferably based on DL-lactide, L-lactide and / or D-lactide, and polyester.

In a preferred embodiment of the multilayer film according to the invention, the adhesion promoter layer (a) is based on a functionalized, completely biodegradable polymer which is the corresponding, non-functionalized, completely biodegradable polymer of layer (c) and / or the corresponding, non-functionalized, completely biodegradable polymer Polymer component of the layer (b) corresponds. Based z. B. the adhesion promoter layer (a) on a functionalized polylactide, so preferably the layer (c) and / or layer (b) is also based on a polylactide, which, however, is not functionalized.

In a further preferred embodiment of the multilayer film according to the invention, the layer (c) contains at least 70% by weight, preferably at least 80% by weight, based on the total weight of the layer (c) of at least one completely biodegradable polymer.

In a further preferred embodiment of the multilayer film according to the invention, the layer (c) contains at least 30% by weight, preferably at least 20% by weight, based on the total weight of the layer (c) of at least one completely biodegradable additive.

As such additives for doping layer (c) of the multilayer film according to the invention, preferably at least one completely biodegradable additive selected from the group comprising dyes, optical brighteners, antiblocking agents, nucleating agents, crystallizing agents, antistatic agents, antifogging agents, lubricants, flexibilizers, modifiers, plasticizers, UV Absorbers, stabilizers, spacers, inorganic fillers, peel or seal additives, antioxidants and process aids can be used.

The layer (c) is preferably present as at least one of the surface layers of the multilayer film according to the invention.

The layer (c) of the multilayer film according to the invention preferably has a layer thickness of from 1 μm to 500 μm, more preferably from 2 μm to 200 μm, very particularly preferably from 3 μm to 150 μm.

In a preferred embodiment of the multilayer film according to the invention, the adhesion promoter layer (a) is arranged at least between the barrier layer (b) and a layer (c).

In a further preferred embodiment, the layers of the multilayer film according to the invention are arranged symmetrically with respect to a central inner barrier layer (b). In this embodiment, the central barrier layer (b) preferably has on each of its surfaces a layer (c) connected in each case via an adhesion promoter layer (a) so that the layer sequence (c) - (a) - (b) - (a) - (c) results for the film according to the invention.

In a further preferred embodiment of the multilayer film according to the invention, which is arranged symmetrically with respect to a central barrier layer (b), the central barrier layer (b) has on each of its surfaces a layer (c ₁ ) connected in each case via an adhesion promoter layer (a), to each of them another layer (c ₂ ) adjoins, to which, if appropriate, a further layer (c ₃ ) may be arranged adjacently, so that the layer sequence (c ₂ ) - (c ₁ ) - (a) - (b) - (a) - (c ₁ ) - (c ₂ ) or (c ₃ ) - (c ₂ ) - (c ₁ ) - (a) - (b) - (a) - (c ₁ ) - (c ₂ ) - (c ₃ ) yields. The individual layers (c ₁ ) or the individual layers (c ₂ ) or the individual layers (c ₃ ) preferably each have an identical composition, ie are based in each case the same proportions on the same fully biodegradable polymers or polymer components and may contain the same fully biodegradable additives in the same amount. Deviating from this respectively identical composition, the symmetrically arranged layers can also each have a different composition. Preferably, in this embodiment, the central barrier layer (b) has on one of its surfaces a layer (c ₁ ) connected via an adhesion promoter layer (a) and on one of its surfaces a layer (c ₂ ) connected via an adhesion promoter layer (a), such that the layer sequence (c ₁ ) - (a) - (b) - (a) - (c ₂ ) results.

In another preferred embodiment, the layers of the multilayer film are arranged asymmetrically with respect to a central barrier layer (b). For this purpose, the layer (c ₁₎ or (c ₂₎ a further layer (c ₁₎ or (c ₂₎ or (c ₃₎ are adjacent, or in turn, in each case one further layer (c ₁₎ (c ₂₎ or (c ₃ ) can adjoin. For example, the layer sequence (c ₃ ) - (c ₂ ) - (c ₁ ) - (a) - (b) - (a) - (c ₂ ) can result. However, in this embodiment, the central barrier layer (b) may also have on its surfaces in each case a layer (c ₁ ) connected via an adhesion promoter layer (a), one of the layers (c ₁ ) having on its surface another layer (c ₁ ) or (c ₂ ) or (c ₃ ), which may in turn each have a further layer (c ₁ ) or (c ₂ ) or (c ₃ ), so that, for example, the layer sequence (c ₁ ) - (a ) - (b) - (a) - (c ₁ ) - (c ₂ ).

The individual layers (c ₁ ), (c ₂ ) and (c ₃ ) may be of identical or different composition, ie be based on the same or different fully biodegradable polymers or polymer components and / or proportions or at least in the presence a fully biodegradable additive in the type and / or amount of this additive differ.

The total layer thickness of the multilayer film according to the invention is preferably 5-3000 .mu.m, more preferably 10-1000 .mu.m, most preferably 15-400 .mu.m.

The multilayer film according to the invention preferably has an oxygen permeability of at most 50 cm ³ / (m ² · 24 h), particularly preferably at most 20 cm ³ / (m ² · 24 h), very particularly preferably at most 10 cm ³ / (m ² · 24 h), particularly preferably of at most 5 cm ³ / (m ² · 24 h), in particular particularly preferably of <2 cm ³ / (m ² · 24 h).

The water vapor permeability of the multilayer film according to the invention is preferably at most 50 g / (m ² · 24 h), particularly preferably at most 20 g / (m ² · 24 h), very particularly preferably at most 10 g / (m ² · 24 h), particularly preferably at most 5 g / (m ² · 24 h), more preferably <2 g / (m ² · 24 h).

The functionalization of the completely biodegradable polymers which are used for the preparation of the adhesion promoter layer (a) according to the invention is known to the person skilled in the art. The functionalization can, for example, by polymer-analogous reactions or by radical polymerization by Covalent linkage (grafting) on the fully biodegradable polymers done. If the functionalization of the completely biodegradable polymers used for the preparation of the adhesion promoter layer (a) by grafting, so this example can be achieved by means of reactive extrusion. Here, the or to be functionalized (s), completely biodegradable (s) polymer (s) is ground to a powder and mixed with a suitable grafting agent such as maleic anhydride in an extruder, preferably in a twin-screw extruder.

Subsequently, an initiator such as. As a peroxide, preferably in the form of a solution, metered to this mixture and thus started the radical polymerization. The functionalized, fully biodegradable polymer is obtained in the form of granules and dried. The degree of functionalization can be determined by means of methods known to the person skilled in the art, for example by means of a titration.

The preparation of the adhesion promoter layer (a) according to the invention and of the multilayer film according to the invention can be carried out by any desired production method, such as, for example, B. by separate extrusion or preferably by co-extrusion.

Both single and all layers of the multilayer film according to the invention can be produced by extrusion, in particular by blown film extrusion and / or flat film extrusion (cast extrusion), or coextrusion, in particular blown film coextrusion and / or flat film coextrusion (Cast-co-extrusion) are formed.

If individual layers of the multilayer film according to the invention are produced separately by one of the above methods, the adhesion promoter can be used to form the adhesion promoter layer (a), for example. B. as a melt or as a liquid preparation, for example as a solution or dispersion, by conventional methods such as spraying or casting on one of the layers of the film of the invention, such as. B. the barrier layer (b) or one of the surface layers applied and another layer are connected thereto. Alternatively, the primer can also be applied to one of the layers, such. B. the barrier layer (c) or one of the surface layers are laminated by extrusion and another layer are connected thereto.

These production methods and corresponding parameters are generally known to the person skilled in the art.

The adhesion promoter layer (a) according to the invention is preferably produced by extrusion.

The multilayer film according to the invention is preferably produced as a whole by coextrusion, wherein a blown film coextrusion process or a flat film coextrusion process is very particularly preferred.

The multilayer film according to the invention can be thermoformed, preferably by deep drawing.

The multilayer film according to the invention can be embossed and / or stretched, preferably monoaxially or biaxially stretched, preferably in a stretch ratio of up to 1: 6, particularly preferably of up to 1: 4.

The multilayer film according to the invention is preferably printable and / or transparent and / or colored and / or sealable and / or optionally siliconizable.

In a very preferred embodiment, the fully biodegradable multilayer film according to the invention consists of five layers: a central barrier layer (b) and two further layers (c) connected to the barrier layer (b) via an adhesion promoter layer (a), so that the Barrier layer (b) has on its two surfaces in each case an adhesive layer (a), each having on its surface a layer (c). The multilayer film according to the invention then has the layer sequence: (c) - (a) - (b) - (a) - (c). The individual layers (c) may be identical or different, i. H. z. B. based on the same fully biodegradable polymers and compositions or on different fully biodegradable polymers and / or compositions, or differ by the presence of at least one biodegradable additive and / or in the nature and / or amount of this additive.

In a further very preferred embodiment, the multilayer film according to the invention consists of a central barrier layer (b) and four further layers (c), of which two each on each Side of the barrier layer (b) are arranged. In this case, the barrier layer (b) has on its two surfaces in each case an adhesion promoter layer (a), which in each case has a layer (c) on its surface.

Each of the layers (c) has another layer (c) on its surface, so that the multilayer film of this embodiment is composed of seven layers. The multilayer film according to the invention then has the layer sequence: (c) - (c) - (a) - (b) - (a) - (c) - (c). The individual layers (c) may be identical or different, i. H. z. B. based on the same fully biodegradable polymers or polymer components or on different fully biodegradable polymers or polymer components, or differ in the presence of at least one biodegradable additive in the nature and / or amount of this additive.

In a further very preferred embodiment, the multilayer film according to the invention consists of a central barrier layer (b) and six further layers (c), of which three are arranged on each side of the barrier layer (b). In this case, the barrier layer (b) has on its two surfaces in each case an adhesion promoter layer (a), which in each case has a layer (c) on its surface. Each of the layers (c) has on its surface two further layers (c), so that the multilayer film of this embodiment consists of nine layers. The multilayer film according to the invention then has the layer sequence: (c) - (c) - (c) - (a) - (b) - (a) - (c) - (c) - (c). The individual layers (c) may be identical or different, ie based for example on the identical fully biodegradable polymers or polymer components or on different completely biodegradable polymers or polymer components, or in the presence of at least one biodegradable Additive in the nature and / or amount of this additive differ. The multilayer film according to the invention can then be, for example, the layer sequence (c ₁ ) - (c ₂ ) - (c ₃ ) - (a) - (b) - (a) - (c ₃ ) - (c ₂ ) - (c ₁ ) exhibit.

In a preferred embodiment, the multilayer film according to the invention is resistant to a film based on at least one thermoplastic polymer selected from the group comprising polyolefins, polyesters, polyamides, cyclic olefin homo- or copolymers (COC) and biodegradable polymers, preferably at least one completely biodegradable polymer laminated, wherein as a laminating adhesive preferably a fully biodegradable Kaschierklebstoff is used.

The cyclic olefin homopolymers or copolymers (COC) used for producing such a film are preferably cyclic olefin copolymers and can u. a. Copolymers of α, β-unsaturated cyclic olefins having 4-10 carbon atoms such as. B. norbornene and thermoplastic α, β-unsaturated olefins such as ethylene or Proplyen be.

The fully biodegradable multilayer films of the present invention can be used to make appropriate packages of any type.

Another object of the present invention is therefore the use of the multilayer film according to the invention for the production of at least one completely biodegradable packaging element, preferably a lid and / or a container or of a fully biodegradable packaging.

A further subject of the present invention is at least one completely biodegradable packaging element, preferably a lid and / or a container of a two-part packaging, of a multilayer film according to the invention.

Packaging, preferably in the form of a completely biodegradable bag made from a multilayer film according to the invention, is likewise a further subject of the present invention.

Particularly preferred are fully biodegradable packages of the multilayer film according to the invention comprising at least one fully biodegradable adhesive layer (a), at least one inner barrier layer (b) and at least one layer (c) or from each of the multilayer films listed above.

Preferably, the packaging according to the invention serve as packaging for a wide variety of goods. Such goods can be both food and toiletries.

The completely biodegradable multilayer films according to the invention can moreover be used as a barrier film, preferably in the case of hygiene articles, particularly preferably in diapers, or as a protective film for feminine hygiene articles.

Another object of the present invention is therefore the use of the fully degradable multilayer film according to the invention as a barrier film or protective film, preferably in hygiene articles.

The present invention relates to a fully biodegradable multilayer film comprising a fully biodegradable primer layer (a) based on at least one functionalized fully biodegradable polymer and a fully biodegradable barrier layer (b) as well as fully biodegradable packaging, barrier films and protective films made therefrom in hygiene articles ,

Determination of bond adhesion

The bond strength is given by the release force in [N / 15 mm] required to separate two layers of a multilayer film from each other.

The layers of a sample of the multilayer film according to the invention, for which the composite adhesion is to be determined, are first mechanically separated from one another at least 50 mm on one side of the sample. Subsequently, the sample is applied to a peel-off roll, which was previously provided over the entire surface with double-sided adhesive tape. The peel roller is installed in a tensile strain tester and the side of the sample which has the separation of the layers is clamped in the upper clamp of the tensile tester. The layers are then pulled apart at a feed rate of the pulling clamp of 100 mm / min until complete separation. To determine the bond strength, a force-strain diagram is recorded and from the peak values obtained, the median and the span of the force corresponding to those in the DIN 53539-79 determined method determined.

If the sample of the multilayer film according to the invention has several layers, then the bond adhesion for each layer must be determined. The layers between which the least adhesion occurs, are first to be separated, otherwise there may be an unwanted separation of several layers simultaneously.

Determination of completely biodegradability

The determination of the complete biodegradability of the multilayer films according to the invention is carried out by the in DIN EN 13432 described method. A method is used to test aerobic compostability with the method ISO 14855: 1999 is identical. The test duration must not exceed a maximum duration of 6 months. The test material to be tested must reach a degree of degradation of at least 90% or 90% of the maximum value of a suitable reference substance in the plateau phase.

Furthermore, a disintegration test is carried out as part of the aerobic composting. In this case, a maximum of 10% of the original dry weight of the test material may be found after composting for a maximum of 12 weeks in a> 2 mm sieve fraction.

The following examples and comparative examples serve to illustrate the invention, but are not to be construed as limiting.

I. Chemical characterization of the raw materials used:

• PLA:

  Polylactide PLA 2002 from Natureworks

  PVOH:

  Mowiflex TC 232 from Kuraray

  EVOH1:

  fully biodegradable fully saponified ethylene-vinyl alcohol copolymer with an ethylene content of 7 mol% of Kuraray

  EVOH2:

  fully biodegradable fully saponified ethylene-vinyl alcohol copolymer with an ethylene content of 7 mol% of Kuraray

  Blend 1:

  Misery of PLA (45% by weight) and Ecoflex F BX 7011 (55% by weight) = Ecovio LBX 8145

  Ecoflex F BX 7011:

  completely biodegradable polyester from BASF

  HV1:

  Adhesion promoter 1: PLA (completely biodegradable) grafted with acid anhydride groups (maleic anhydride)

  HV2:

  Adhesion promoter 2: PLA (completely biodegradable) grafted with acid groups (acrylic acid)

  HV3:

  Adhesion promoter 3: mixture of HV1 and misery 1 (ratio 1: 1) (completely biodegradable)

  HV 4:

  Adhesive 4: Blend of HV1 and PLA (ratio 1: 1) (fully biodegradable)

  Admer NF 498 E:

  non-biodegradable adhesion promoter: polyethylene grafted with acid anhydride groups (maleic anhydride), manufacturer Mitsui

  Admer QB 520 RE:

  non-biodegradable adhesion promoter: polypropylene grafted with acid anhydride groups (maleic anhydride), manufacturer Mitsui

  EASC:

  non-biodegradable adhesion promoter: ethylene-acrylic acid ester copolymer grafted with acid anhydride groups (maleic anhydride)

  WE

  completely biodegradable plasticizer

II. Production of multilayer films

The multilayer films of Comparative Examples 1 to 4 and Examples 1 to 4 each consist of 5 layers, have a total layer thickness of 60 .mu.m and were produced by blown film coextrusion. The multilayer films of Examples 5 and 6 each consist of 7 layers, have a total layer thickness of 400 microns and were prepared by cast co-extrusion. The layers of the individual multilayer films each adjoin one another directly in the order in which they are listed below.

III. Comparative Examples

All subsequent% data are each wt%. III.1 Comparative Example 1 (V1): Layer (c) (20 μm): 100% PLA Layer (c) (5 μm): 100% PLA Layer (b) (10 μm): 100% PVOH Layer (c) (5 μm): 100% PLA Layer (c) (20 μm): 100% PLA III.2 Comparative Example 2 (V2): Layer (c) (20 μm): 100% PLA Layer (a) (5 μm): 100% Admer QB 520 E Layer (b) (10 μm): 100% PVOH Layer (a) (5 μm): 100% Admer QB 520 E Layer (c) (20 μm): 100% PLA III.3 Comparative Example 3 (V3): Layer (c) (20 μm): 100% PLA Layer (a) (5 μm): 100% Admer NF 498 E Layer (b) (10 μm): 100% PVOH Layer (a) (5 μm): 100% Admer NF 498 E Layer (c) (20 μm): 100% PLA III.4 Comparative Example 4 (V4) (according to WO 2007/135037 ): Layer (c) (20 μm): 100% PLA Layer (a) (5 μm): 100% EASC Layer (b) (10 μm): 100% PVOH Layer (a) (5 μm): 100% EASC Layer (c) (20 μm): 100% PLA

IV. Examples

All subsequent% data are each wt%. IV.1 Example 1 (B1) Layer (c) (20 μm): 100% PLA Layer (a) (5 μm): 100% HV1 Layer (b) (10 μm): 100% PVOH Layer (a) (5 μm): 100% HV1 Layer (c) (20 μm): 100% PLA IV.2 Example 2 (B2) Layer (c) (20 μm): 100% PLA Layer (a) (5 μm): 100% HV2 Layer (b) (10 μm): 100% PVOH Layer (a) (5 μm): 100% HV2 Layer (c) (20 μm): 100% PLA IV.3 Example 3 (B3) Layer (c) (20 μm): 100% PLA Layer (a) (5 μm): 100% HV3 Layer (b) (10 μm): 100% PVOH Layer (a) (5 μm): 100% HV3 Layer (c) (20 μm): 100% PLA IV.4 Example 4 (B4) Layer (c) (20 μm): 100% PLA Layer (a) (5 μm): 100% HV1 Layer (b) (10 μm): 100% EVOH1 Layer (a) (5 μm): 100% HV1 Layer (c) (20 μm): 100% PLA IV.5 Example 5 (B5) Layer (c ₂ ) (80 μm): 100% PLA Layer (c ₁ ) (97.5 μm): 95% PLA and 5% WE Layer (a) (15 μm): 100% HV1 Layer (b) (15 μm): 100% EVOH1 Layer (a) (15 μm): 100% HV1 Layer (c ₁ ) (97.5 μm): 95% PLA and 5% WE Layer (c ₂ ) (80 μm): 100% PLA IV.6 Example 6 (B6) Layer (c ₂ ) (80 μm): 100% PLA Layer (c ₁ ) (97.5 μm): 100% PLA Layer (a) (15 μm): 100% HV4 Layer (b) (15 μm): 100% EVOH2 Layer (a) (15 μm): 100% HV4 Layer (c ₁ ) (97.5 μm): 100% PLA Layer (c ₂ ) (80 μm): 100% PLA

V. Compound liability

For all multilayer films of Examples 1-6 and Comparative Examples 1-4, respectively, the composite adhesion of the adhesion promoter layer (a) to the barrier layer (b) or to layer (c) was determined by the method described above. In each case, the lowest values for the composite adhesion are determined, which were determined for adjacent layers of the respective multilayer films. V1: 0.2 N / 15 mm (delamination between (a) and (b)) V2: 0.6 N / 15 mm (delamination between (a) and (c)) V3: 1.1 N / 15 mm (delamination between (a) and (c)) V4: 17.9 N / 15 mm (very good adhesion between (a) and (c)) B1: > 25 N / 15 mm (not separable) B2: 15.2 N / 15 mm (very good adhesion between (a) and (c)) B3: 8.3 N / 15 mm (good adhesion between (a) and (c)) B4: > 25 N / 15 mm (not separable) B5: > 25 N / 15 mm (not separable) B6: 11.4 N / 15 mm (good adhesion between (a) and (c))

In the case of the multilayer film V1, an adhesion promoter of unfunctionalized PLA was used.

There was a delamination between the adhesion promoter layer (c) and the barrier layer (b) of PVOH. This proves that with non-functionalized PLA as adhesion promoter no composite adhesion to the barrier layer (b) can be achieved and a functionalization of the adhesion promoter is necessary.

In the case of the multilayer films V2 and V3, although a (commercially available) functionalized adhesion promoter was used, it is based on a non-biodegradable polyolefin (polypropylene or polyethylene). In each case an inseparable adhesion of the adhesion promoter to the barrier layer (b) of PVOH could be achieved, but delamination occurred between the layer (c) of PLA and the adhesion promoter (a). This demonstrates that composite adhesion to PLA can not be achieved with a non-biodegradable coupling agent such as functionalized polypropylene or functionalized polyethylene.

In the case of the multi-layer film V4, a bonding agent of a non-biodegradable functionalized ethylene-acrylic acid ester copolymer was used. The measurement of the adhesion of the adhesion promoter layer (a) to the layer (c) of PLA of this film gave a value of 17.9 N / 15 mm. Accordingly, a very good composite adhesion of the multilayer film was found, i. H. The multilayer film could be delaminated at this position only with great effort. Furthermore, an inseparable adhesion of the adhesion promoter to the barrier layer (b) could be achieved from PVOH. However, the adhesion promoter used is not completely biodegradable, so that it can be used only to a limited extent since the resulting multilayer film is not completely biodegradable.

In the case of the multilayer films B1-B6, adhesion promoters based on fully biodegradable functionalized PLA (HV1, HV2, HV3 and HV4) were used in each case to provide a barrier layer (b) of PVOH or an ethylene-vinyl alcohol copolymer (EVOH1 or EVOH2) a layer (c) of PLA to connect. In the case of the multilayer film of examples B1, B4 and B5, the layers can no longer be separated from one another (bond adhesion> 25 N / 15 mm).

For the multilayer films B2, B3 and B6, a very good or good adhesion of the respective adhesion promoter layer to the layer (c) of PLA of the multilayer film was found, ie. H. the multilayer film could only be delaminated at this position with very great or great force expenditure (bond adhesion 15.2 N / 15 mm or 8.3 N / 15 mm or 11.4 N / 15 mm).

VI. Biodegradability

The multilayer films of examples B1-B6 according to the invention are according to DIN EN 13432 completely biodegradable, ie in the context of the above-described method for determining the biodegradability and the disintegration test these multilayer films are degraded after 12 weeks to at least 90%.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2007/135037 [0005, 0085]

Cited non-patent literature

• DIN EN 13432 [0010]
• ISO 1133 [0023]
• DIN 53539-79 [0079]
• DIN EN 13432 [0081]
• ISO 14855: 1999 [0081]
• DIN EN 13432 [0094]

Claims (27)

A fully biodegradable multi-layer film comprising (A) at least one fully biodegradable adhesive layer (a) based on at least one functionalized, fully biodegradable polymer and (B) at least one preferably internal, completely biodegradable barrier layer (b). A multilayer film according to claim 1, characterized in that the primer layer (a) is based on at least one functionalized, fully biodegradable polymer having at least one class of functional groups selected from the group consisting of epoxide groups, peroxide groups, hydroxyl groups , Amine groups, amide groups, carboxyl groups and acid anhydride groups, preferably cyclic acid anhydride groups. A multilayer film according to claim 1 or 2, characterized in that the adhesion promoter layer (a) based on at least one functionalized, fully biodegradable polymer having a degree of functionalization of 0.05 to 30 mol%. A multilayer film according to any one of claims 1-3, characterized in that the adhesion promoter layer (a) on at least one functionalized fully biodegradable polymer selected from the group comprising lactic acid homo- and copolymers, polyhydroxyalkanoates, cellulose, cellulose derivatives, (thermoplastic) Starch, polyesters, preferably polycaprolactones, polyethers, polyols and copolymers of at least two monomers of said polymers, wherein each of the aforementioned polymers is functionalized. A multilayer film according to any one of claims 1-4, characterized in that the adhesion promoter layer (a) on at least one functionalized, fully biodegradable polymer selected from the group comprising lactic acid homopolymers or copolymers, preferably polylactides, particularly preferably based on DL-lactide , L-lactide and / or D-lactide, wherein each of the aforementioned polymers is functionalized. A multilayer film according to any one of claims 1-5, characterized in that the adhesion promoter layer (a) as further polymer component at least one non-functionalized, fully biodegradable polymer selected from the group comprising lactic acid homo- and copolymers, preferably polylactides, particularly preferred based on DL-lactide, L-lactide and / or D-lactide, polyhydroxyalkanoates, cellulose, cellulose derivatives, (thermoplastic) starch, polyesters, preferably polycaprolactones, polyethers and copolymers of at least two monomers of said polymers. A multilayer film according to claim 6, characterized in that the adhesion promoter layer (a) as further polymer component 0.1 to 50 wt .-%, preferably from 1 to 40 wt .-%, particularly preferably from 5 to 30 wt % of at least one unfunctionalized fully biodegradable polymer and optionally up to 50% by weight, preferably up to 60% by weight, more preferably up to 70% by weight of at least one functionalized, fully biodegradable polymer contains. A multilayer film according to any one of claims 1-7, characterized in that the adhesion promoter layer (a) has a melt index (MFI) of 0.2 to 100 g / 10 min, preferably from 0.5 to 30 g / 10 min, more preferably from 1 to 20 g / 10 min (at 190 ° C and 2.16 kg). A multilayer film according to any one of claims 1-8, characterized in that the barrier layer (b) is a gas barrier layer, preferably an oxygen barrier layer, a water vapor barrier layer, an oil barrier layer or a barrier layer against fragrances and / or flavors. A multilayer film according to any one of claims 1-9, characterized in that the barrier layer (b) based on at least one fully biodegradable polymer, preferably at least one fully biodegradable at least partially hydrolyzed polyvinyl acetate or at least one fully biodegradable ethylene-vinyl alcohol copolymer. A multilayer film according to claim 10, characterized in that the barrier layer (b) comprises at least one at least partially hydrolyzed polyvinyl acetate which has a degree of saponification of at least 50 mol%, preferably of at least 75 mol%, or on at least one ethylene-vinyl alcohol Copolymer, which has an ethylene content of at most 20 mol%, preferably of at most 10 mol% based. A multilayer film according to any one of claims 1-11, characterized in that the barrier layer (b) at least one lactic acid homo- or copolymer, preferably at least one polylactide, particularly preferably based on DL-lactide, L-lactide and / or D-lactide as another fully biodegradable polymer component. A multilayer film according to claim 12, characterized in that the barrier layer (b) from 0.1 to 50 wt .-%, preferably from 1 to 40 wt .-%, particularly preferably from 5 to 30 wt .-%, based to the total weight of layer (b), at least one lactic acid homo- or copolymer as further fully biodegradable polymer component. A multilayer film according to any one of claims 1-13, characterized in that the multilayer film as a further fully biodegradable layer (c) having at least one layer (c) based on at least one fully biodegradable polymer. A multilayer film according to claim 14, characterized in that the layer (a) is based on at least one functionalized, fully biodegradable polymer containing the corresponding unfunctionalized, fully biodegradable polymer of layer (c) and / or the corresponding non-functionalized, complete biodegradable polymer component of the barrier layer (b). A multilayer film according to claim 14 or 15, characterized in that the layer (c) on at least one fully biodegradable polymer selected from the group comprising lactic acid homo- and copolymers, polyhydroxyalkanoates, cellulose, cellulose derivatives, thermoplastic starch, polyester, preferably Polycaprolactones, polyethers, polyols and copolymers based on at least two monomers of said polymers. A multilayer film according to any one of claims 14-16, characterized in that the layer (c) on at least one fully biodegradable polymer selected from the group comprising lactic acid homo- and copolymers, preferably polylactides, more preferably polylactides based on DL-lactide, L-lactide and / or D-lactide. A multilayer film according to any one of claims 14-17, characterized in that the layer (c) at least 70 wt .-%, preferably at least 80 wt .-%, based on the total weight of the layer (c), of at least one completely biodegradable Contains polymer. A multilayer film according to any one of claims 1-18, characterized in that the layer (c) at least one of the surface layers of the multilayer film and the layer (a) between the barrier layer (b) and the layer (c) is arranged. A multilayer film according to any one of claims 1-19, characterized in that the layers of the multilayer film are arranged symmetrically with respect to a central barrier layer (b), wherein the central barrier layer (b) on each of its surfaces via a respective one primer layer (a) having interconnected layer (c) and optionally further layers (c). A multilayer film according to any one of claims 1-19, characterized in that the layers of the multilayer film are arranged asymmetrically with respect to a central barrier layer (b). A use of the multilayer film according to any one of claims 1-21 for the production of at least one completely biodegradable packaging element, preferably a lid and / or a container of a packaging. A fully biodegradable packaging element, preferably a lid and / or a container of a two-part packaging, of a multilayer film according to any one of claims 1-21. A fully biodegradable package of a multilayer film according to any one of claims 1-21, preferably a bag. A package according to claim 24, characterized in that the package is a food package. A package according to claim 24, characterized in that the package is a package for sanitary articles. A fully biodegradable barrier film or protective film for sanitary articles, preferably for diapers or feminine hygiene articles.