WO2011135086A1

WO2011135086A1 - Peelable, at least 50% biodegradable film arrangement, packaging comprising the film arrangement and method for producing the film arrangement

Info

Publication number: WO2011135086A1
Application number: PCT/EP2011/056864
Authority: WO
Inventors: Kurt Stark; Karl Mauser
Original assignee: Huhtamaki Forchheim Zweigniederlassung Der Huhtamaki Deutschland Gmbh & Co. Kg
Priority date: 2010-04-30
Filing date: 2011-04-29
Publication date: 2011-11-03

Abstract

One embodiment of the invention relates to a peelable, at least 50% biodegradable film arrangement (1) having seal bond strength of < 15 N/15 mm against a polyhydroxy carboxylic acid layer, comprising at least: a first film layer (5A), which comprises a polyhydroxy carboxylic acid and a softener, and a peel layer (10), which comprises a mixture of a polyhydroxy carboxylic acid and at least 25 wt % relative to the peel layer of a biodegradable polyester that is different from polyhydroxy carboxylic acid, and the peel layer forms an outer layer of the film arrangement (1). Such a film arrangement has excellent seal bond strength.

Description

description

Peelable, at least 50% biodegradable

Foil assembly, packaging with the foil assembly and

Process for producing the film arrangement

This patent application claims the priorities of

German Patent Application No. 10 2010 018 866.2 and German Patent Application No. 10 2010 046 301.9, whose

Disclosures are hereby incorporated by reference.

Films made of biodegradable, thermoplastic

Plastics such as polyhydroxycarboxylic acids such as polylactic acid (also referred to as polylactide or PLA) are used in the packaging industry, among others

Packaging of food and other goods used. Such films are very popular because they are both compostable and produced on the basis of renewable raw materials, but on the other hand also have many advantages of conventional thermoplastic polymers based on polyolefins.

In many different packaging, especially in food packaging, there is a need to open the packaging in a simple manner by opening a so-called top film opposite a bottom film. The required effort should not be so high and below 15 N / mm, so that the packaging can be opened easily by the consumer. Some packaging based on polyhydroxycarboxylic acids, such as

Polylactides, when sealed against themselves, exhibit very high seal strengths from Part more than 20 N / 15 mm up. Such high seal seam ^¬ strengths can also cause that the sealing seams have a higher strength as a rule, than the upper ^¬ or lower film itself so that it can come to a tearing of the film, the so-called cohesive failure upon peeling of the films.

Further, a problem of film assemblies and also packaging materials based on polyhydroxycarboxylic acids, such as PLA, is that they have considerable rigidity and low tear strength

exhibit. This rigidity disadvantageously limits the fields of use of the films. Even a slight tearing of the film is not desired by the consumer, since the film in one piece - and not in several fragments - should be deducted.

From the document WO 2007/113077 Al a more ^¬ layer film is known which includes a peelable top layer of a mixture of a polylactic acid with a biodegradable starch, cellulose or a degradable polyester. Furthermore, a base layer is present which has polylactic acids. Such a film has a seal seam strength of 1 to 7 N / 15 mm with respect to itself. However, this multilayer film is relatively expensive, easily tearing and also very stiff.

It is therefore the object of some embodiments of the present invention which are known in the art

to reduce known disadvantages mentioned above. This technical problem is solved by a peelable, biodegradable film assembly according to claim 1 and a peel ^¬ capable package according to claim 15 °. Procedure for Production of the film arrangement are the subject of further claims.

One embodiment of the present invention relates to a peelable, at least 50% biodegradable

Foil arrangement with a seal seam strength of <15 N / 15 mm against a polyhydroxycarboxylic acid layer, with at least:

- a first film layer comprising a polyhydroxy ^¬ carboxylic acid and a plasticizer, and

- a peeling layer comprising a mixture of a polyhydroxy ^¬ carboxylic acid and at least 25 wt% based on the

Peel layer of a biodegradable polyester, wherein the peel layer forms an outer layer of the film assembly.

The biodegradable ester is different from the polyhydroxycarboxylic acid, which is already biodegradable per se. With such a film arrangement, the polyhydroxycarboxylic acid dispersed in a continuous phase of the biodegradable polyester is generally present, resulting in a good peelability of the film arrangement. Furthermore, such a film arrangement for polyhydroxycarboxylic atypical high flexibility, tear resistance, impact resistance and also at the same time

Low toughness, since the first film layer in addition to the polyhydroxycarboxylic acid still has a plasticizer which reduces the naturally high rigidity of the polyhydroxycarboxylic acid.

The seal seam strength or also the bond adhesion of the

Film arrangement in N / 15 mm indicates the separation force required to separate two layers of a multilayer film

or from each other sealed films is required. For this purpose, two adjacent layers in a multilayer film, whose seal seam strength is to be determined, separated on one side at least 50 mm wide mechanically far from each other and then brought the sample on a Abziehrolle, which was previously provided over the entire surface with double-sided adhesive tape. The stripping roller is installed in a tensile-strain testing machine and that side of the sample, which has the already segregated layers is clamped in the upper clamp of the tensile-strain ^¬ testing machine. The layers are then pulled apart at a feed rate of the pulling clamp of 100 mm / min until complete separation. to

Determination of the seal strength is recorded while a force-strain diagram and from the obtained

Peak values of the median and the range of the force

determined according to the method described in the German industrial standard DIN 53539-79.

If a film arrangement has several layers, then the seal seam strength is to be determined for each layer according to the above-mentioned method. The layers between which the lowest seal seam strength occurs are to be separated first, otherwise they will be separated from others

Layers for unwanted separation of multiple layers can come at the same time.

For the purposes of the invention, "biodegradable films" means films which are prepared in accordance with the process described in the German industrial standard DIN EN 13432

completely biodegradable. A method is used to test the aerobic compostability, which is identical to the ISO 14855: 1999 method. The test duration may be a maximum duration of six Do not exceed months. The film arrangement to be tested must have a degree of degradation of at least 90% or 90% of the maximum value of one in the plateau phase

reach suitable reference substrate. Furthermore, a

Disintegration test carried out in the context of aerobic composting. After composting for a maximum period of 12 weeks in a> 2 mm sieve fraction, a maximum of 10% of the original dry weight of the

Test material can be found. One at least 50%

biodegradable Folienanordung is degradable at least 50% by weight according to the method described above. More preferably, such a foil arrangement is at least 60%, 70%, 80%, 90% or even completely biodegradable.

The peelable, at least 50% biodegradable

Film arrangement according to the above-mentioned embodiment of the invention advantageously has a seal seam strength of ^¬ <15 N / 15 mm, preferably below 10 N / 15 mm, most preferably less than 5 N / 15 mm on. It is furthermore preferred if a packaging material that contains the

contains peelable, biodegradable film assembly, with a force of about 1 N / 15 mm can open up to about 15 N / 15 mm, in which the cover sheet is removed from the bottom sheet. With a seal seam strength of> 15 N / 15 mm, in particular at values of> 20 N / 15 mm, the top film can often no longer be removed from the bottom film due to the high adhesion, so that the cohesive break already mentioned above occurs.

The peelable, biodegradable film layer arrangement can be sealed with other films based on polyhydroxycarboxylic acids, in which case the preferred low seal seam strengths of less than 15 N / 15 mm result while the film assembly has increased elongation at break, toughness, strength and stability.

The inventors have also found that at levels of less than 25% by weight of the biodegradable polyester on the scrub layer, the seal seam strength becomes unacceptably high and can easily reach values of> 20 N / 15 mm. With a proportion of at least 25% by weight of the biodegradable polyester on the peel layer, the entire

peelable, biodegradable film assembly by standard conditions, for example, temperatures of 80 to 120 ° C, a pressure of 0.5 bar to 10 bar and a

Time span of 0.5 s to 10 s seal well with other polyhydroxy-carboxylic acid films.

The plasticizer in the first film layer may be selected from glycerol, citric acid ester and

Polyalkylene glycols or any mixture of these plasticizers. These plasticizers are particularly suitable for use in film layer arrangements based on

Polyhydroxycarboxylic acids.

More preferably, the plasticizer is a polyalkylene glycol having a molecular weight of at least 1000. In

Polyalkylene glycols of this molecular weight can

on the one hand to be sure that the first

Film layer has sufficient softness,

On the other hand, due to the high molecular weight of the plasticizer, out-diffusion of the plasticizer from the first film layer is greatly reduced or prevented. Such plasticizers also do not lead to an adverse discoloration of the plastic or

Odor nuisance. Polyethylene can particularly preferably or polypropylene glycol having a molecular weight greater than 8,000, more preferably between 25,000 and 4 million, most preferably around 35,000. Polyethylene or polypropylene glycols with such high molecular weights are solids, so that out-diffusing this

Plasticizer from the first layer of film can be effectively prevented. Furthermore, it is possible that the

Polyalkylene glycol plasticizers are modified with a functional group, in particular a carboxylic acid function.

The mechanical properties of the biodegradable peelable film arrangement can be influenced particularly advantageously if the plasticizer is present in the first film layer in a proportion of about 1 to 20% by weight, preferably from 3 to 15% by weight.

As polyhydroxycarboxylic acids it is possible to use polymers based on various hydroxycarboxylic acids,

for example, α-hydroxycarboxylic acids, such as glycolic acid or lactic acid, β-hydroxycarboxylic acids, such as mevalonic acid or 3-hydroxybutyric acid. A preferred variant of a polyhydroxycarboxylic acid is a polylactide, polylactic acid. Monomers of polylactide may be D- or L-hydroxycarboxylic acids. The preparation of the polylactic acid takes place via catalytic ring-opening polymerizations of lactide, an annular condensation product of two lactic acid molecules, the 1, 4-dioxane-3, 6-dimethyl-2, 5-dione. The preparation of polylactic acid or polylactide is also described, for example, in US Pat. Nos. 5,208,297 or 5,357,035, to which reference is hereby incorporated by reference. It is also possible to use co-polymers of lactic acid or other polyhydroxycarboxylic acids which have different monomer units. Polylactides are easy to prepare, biodegradable polyhydroxy- carboxylic acids, which are also food-compatible.

For example, polylactides from Nature Works®, for example the PLA polymer 2002D, can be used.

It is also possible to use polyhydroxyalkanoates of

general formula:

0 - unend me

10 such as poly-4-hydroxybutyrate, poly-3-hydroxybutyrate and poly-3-hydroxyvalerate or their co-polymers.

The biodegradable polyester, which is different from the polyhydroxycarboxylic acid, for example, by

Polymerization of a mixture consisting of:

Adipic acid, its ester-forming derivatives, or

Mixtures thereof,

Terephthalic acid, its ester-forming derivatives, or

Mixtures thereof and

- C ₂ to Ce alkanediols, C5 to C ₁₀ cycloalkanediols, or mixtures thereof, be prepared. As C2 to Ce alkanediol is preferably 1, 4-butanediol

used. The synthesis of such biodegradable polyesters is described, for example, in granted EP patents EP 0 792 309 B1 and EP 1 838 784 B1, to which reference is hereby made by full reference.

These polyesters are particularly biodegradable, but form with other polyhydroxycarboxylic acids, such as

For example, polylactide a polymer blend with a

Domain structure. Depending on the concentrations of the polyhydroxycarboxylic acids and the biodegradable

Polyesters either the polyester form a continuous phase, are embedded in the domains of polyhydroxycarboxylic acid, or vice versa. This results in the formation of a homogeneous domain-like "sponge" structure, especially when prefabricated blends of the biodegradable polyester are used with the polyhydroxycarboxylic As polymer blends of PLA and the biodegradable polyester polymer blends such as Ecovio®, especially Ecovio® L BX 8145 BASF, through the use of prefabricated,

compounded mixtures of the biodegradable

Polyester and a polyhydroxycarboxylic acid can be

Peelschichten produce, the peel over the entire peel homogeneous peel properties and no turbidity

exhibit. The% by weight of the biodegradable

Polyester in the peel layer can be over the

Adjust addition of additional polyhydroxycarboxylic acids.

Furthermore, the biodegradable polyester can also be used in pure form, for example the product

Ecoflex® F BX 7011 from BASF. According to another embodiment of the present invention

It is advantageous if the biodegradable polyester is present in a proportion of at least 35 to 80% by weight, preferably 35 to 70% by weight, particularly preferably 45 to 65% by weight, in the peel layer, since then particularly good Sealed seam strengths of less than 15 N / 15 mm, in particular particularly good seal seam strengths of less than 6 N / 15 mm, preferably less than 4 N / 15 mm, more preferably less than 3.5 N / 15 mm can be achieved.

Furthermore, the peel layer of the invention

Foil assembly according to one embodiment of the invention, be free of adhesion promoters or other adhesives. In the above standard conditions, the peelable

Seal film assembly with other polyhydroxycarboxylic acid films without further use of adhesion promoters or adhesives and adhesives. The sealability of the present biodegradable film arrangement can therefore be ensured solely by the mixture of the polyhydroxycarboxylic acid and the at least 25% by weight of the biodegradable polyester.

In further embodiments of the invention, the

Foil assembly further film layers comprising a polyhydroxycarboxylic acid with a plasticizer and which are arranged on the first film layer. By the

Inclusion of additional film layers can be the one hand, vary the thickness of the film arrangement particularly well and vary the other hand, advantageously by different plasticizers ^¬ concentrations in the various film layers, the mechanical strength of the film. It is also possible, more biodegradable Use film layers that have no plasticizers.

In accordance with a further embodiment of a film arrangement according to the invention, the first film layer located in the interior of the film arrangement has a higher one

Proportion of plasticizer, as the further outward located at least one further film layer. It can

in particular, the farther out in the film assembly

have a plasticizer content between 0.1 to 10% by weight, in particular between 0.1 to 5% by weight and the inner layer of a respective higher proportion of plasticizer. In such a film arrangement, the mechanical strength of the film can be advantageously increased due to the inner layer with the higher plasticizer content, without the blocking tendency of the

Foil arrangement becomes too high. The blocking tendency, ie the wedging of the different films against each other, can be particularly well by the farther out in the

Foil assembly located film layers are reduced or prevented with a lower plasticizer content.

The film layers present in the film arrangement and / or the peel layer may contain further additives, such as, for example, dyes, for example the

Foil assembly to give a particular color impression and also to allow printed shapes on the film assembly.

Furthermore, it is possible that as a further outer layer on the film arrangement, a cover layer is present, which also contains a polyhydroxycarboxylic acid. Such a further cover layer may, for example, even more Additives, such as anti-blocking and slip additives, which have a significant influence on the coefficient of friction of the film assembly against itself or against other substrates such as steel or glass.

In particular, the cover layer can also have a

Contain plasticizer, but their proportion is preferably in

Compared to the inner film layers is reduced in order to reduce or prevent the blocking tendency between multiple film assemblies.

According to a further embodiment of a film arrangement according to the invention, this additionally has a barrier layer at least against oxygen and / or water. One of the ^¬ like Folienanordung is particularly suitable to protect the packaged goods, which is packaged by this Folienanordung against external influences, such as oxygen and / or water vapor. The barrier layer can also be a barrier to oil and flavorings and thus the

Pack the packaged goods aroma-tight.

Furthermore, the barrier layer of the film arrangement can have a permeability of <10, preferably <5, more preferably <2 g / m ^{2 »} day for water and a permeability of <10,

preferably <5 cm ³ / m ^{2 »} day for oxygen. The

Permeabilities or transmission rates can be determined, for example, by means of coulometric measurement methods. For Permeationsmessung conventional devices we can

Example for measuring the oxygen transmission OX-TRAN®, for measuring the water vapor transmission PERMATRAN-W® or for measuring the carbon dioxide transmission PERMATRAN-C®, which are distributed by PAUL LIPPKE HANDELS-GMBH. The measurement of the water vapor transmission can thereby in particular according to the standards DIN 53122 Part 2 and ISO 15106-3 and the measurement of the oxygen transmission according to the ASTM D 3985 standard.

According to a further embodiment of the invention, the barrier layer contains a polymer selected from: polyamide, polypropylene, polyethylene, cycloolefin copolymer and ethylene-vinyl alcohol copolymer and mixtures thereof. The barrier layer can also be made of the polymers mentioned and their

Mixtures exist.

Cycloolefin copolymers can be prepared by polymerization of cyclic, unsaturated organic monomers with ethylene. For example, norbornene and

Tetracyclododecen be polymerized with ethene. Ethylene-vinyl alcohol copolymer can be prepared by the polymerization of ethylene and vinyl acetate and has good barrier properties against oxygen and water and can be used particularly well for the packaging of sensitive foods. An example of an ethylene-vinyl alcohol copolymer is Soarnol® available from Nippon Gohsei or Soarus L.L.C. is sold. The polymers mentioned above all have particularly good barrier properties

Oxygen and / or water and water vapor.

Furthermore, in a variant of a film arrangement, an adhesion promoter layer may be present, which is between the

Barrier layer and the first film layer is arranged. The primer layer may provide improved bonding between the barrier layer and the other layers of the film assembly, such as the polyhydroxycarboxylic acid containing film layers. In a variant of the invention are on both sides of a barrier layer Adhesive layers for connection to the others

Foil layers of the peelable Folienanordung available.

For example, ethylene vinyl acetate polymers, acidic groups, anhydride groups or acrylate-modified ethylene-acrylate resins and acrylate-modified HDPE or LDPE resins may be present in the primer layer. An example of materials for the

Adhesive layer are the polymers sold by DuPont® under the trade name Bynel®.

Furthermore, the degree of biodegradability of the peelable Folienanordung of the composition and the proportion of the barrier layer on the Folienanordung be significantly determined. For example, in certain embodiments, a non-degradable or poorly biodegradable barrier layer may be used in peelable film assemblies of the present invention that reduces the biodegradability of the overall film assembly. But it is also possible to use fully biodegradable

Barrier layers, such as polyvinyl alcohol.

The layer thicknesses of the barrier layers can be between 1 and 150 .mu.m, preferably between 3 and 10 .mu.m for blown films and between 3 and 25 .mu.m for cast films. The

Layer thicknesses of the adhesion promoter layers can be between 2 and 20 μm, preferably between 3 and 10 μm.

Furthermore, a barrier layer can be obtained by applying a, preferably biodegradable, barrier coating as a coating to a film arrangement according to the invention

applies. This coating can be used, for example, as an outer coating on one or both sides of the Foil arrangement can be applied, and may be the same or different. The barrier layer is preferably applied to the non-peelable film side, if present, since a coating of the peel layer could negatively influence the peel properties of the film arrangement.

Suitable materials for the barrier coating are, for example, silicon oxide or aluminum oxide coatings and other metallizations, which are by means of physical vapor

Deposition (PVD), chemical vapor deposition (CVD) or by means of atomic layer deposition (ALD) can be generated. Also possible are barrier layers which contain polyvinylidene chloride (PVDC) or coatings based on acrylic, for example barrier layers, which comprise a PET layer as base layer and a modified PAA (polyacrylic acid) as barrier layer (Besela® from Kureha). It is also possible to use plastic films which contain or consist of, for example, PE or PET and which are coated with barrier layers as oxygen barriers (Kurarister® from Kuraray Company Ltd.).

The peelable Folienanordungen that contain barrier layers can be particularly easy by coextrusion or by laminating, ie by gluing

Film layers, for example by means of an adhesive or by heat and pressure, are produced. In this case, the primer layers may act as laminating adhesives.

Another embodiment of the invention is a peelable, at least 50% biodegradable

Packaging comprising: a first film arrangement comprising a first film layer containing a polyhydroxycarboxylic acid, and

Peel layer of a biodegradable polyester comprises and

a second film comprising a polyhydroxycarboxylic acid

that is free of the biodegradable

Polyester is,

- wherein the peel layer of the first film assembly is sealed against the second film with a sealed seam strength of <15 N / 15 mm.

As already mentioned above, the biodegradable polyester is different from the polyhydroxycarboxylic acid. Unlike the prior art, the inventors have

Surprisingly, it has been found that a film layer arrangement comprising a peel layer of the mixture of a polyhydroxycarboxylic acid and a biodegradable

Polyester, can be sealed against films containing a polyhydroxycarboxylic acid, but not the biodegradable polyester. Such peelable packaging is thus much cheaper to produce than packaging from the prior art, since in particular the mixture of polyhydroxycarboxylic acid with the biodegradable polyester is very expensive and in the prior art only seals the mixture of polyhydroxycarboxylic acid with the biodegradable polyester against itself are known. In particular, the inventors have surprisingly found that under standard sealing conditions of 80 to 120 ° C, a pressure of 0.5 to 10 bar and a sealing time ^¬ span of 0.5 to 10 s good seal strength of less than 15 N / 15 mm can be achieved against polyhydroxycarboxylic acid films alone.

Between the first film arrangement and the second film, a cavity is formed in the peelable packaging, which serves for receiving packaged goods, for example foods, and which is accessible by opening the first film arrangement against the second film.

The first film arrangement can be used both as a bottom film or as a top film, the second film then correspondingly forms the counter-film. According to this embodiment of the invention, the mixture of a

Polyhydroxycarboxylic acid and at least 25% by weight of a

biodegradable polyester, which requires the good Peelfähigkeit the packaging, be present only in the bottom or the top film, but not in both films.

Furthermore, it is advantageous that the first film arrangement has the suitability for deep drawing or thermoforming.

In particular, when the first film assembly is part of the bottom film and this has the shape of a cup or a shell, which is formed by the thermoforming. PLA as the preferred polyhydroxycarboxylic acid fulfills all prerequisites for deep drawing or

Thermoforming and can be on the usual equipment

Excellent thermoforming, wherein the temperature range during deep drawing between 75 ° C and 120 ° C, preferably 90 ° C - 100 ° C is selected.

In particular, a good sealability of the packaging can be achieved if the polyhydroxycarboxylic acid of the first film arrangement and the polyhydroxycarboxylic acid of the second film are the same, for example, a polylactide. As already mentioned above, it is also possible that in each case one in the first film layer of the first film arrangement

Plasticizer with the above-mentioned technical

Benefits may be present.

The second film may also be part of a second,

multilayer film assembly comprising further films, such as a cover sheet. The other films are preferably also biodegradable and include polyhydroxycarboxylic acids, such as PLA.

Both the first film arrangement, as well as the second film, or in the case of several layers, the second film arrangement of the packaging according to the invention can all have the features of the first film arrangement already mentioned above.

According to a further embodiment of the invention, packages for packaged goods are provided in which one of the two film arrangements, the bottom or the cover film is thicker than the respective other film arrangement. The thinner Folienanordung may have a thickness of 10 - 80 ym (preferably blown films) and the thicker film assembly has a thickness of 150 - 1000 ym (preferably cast films).

Particularly preferably, the thicker film is the bottom film, which is shaped, for example, in the form of a shell and receives the packaged goods, wherein the thinner lidding film then seals the bottom film. The peel layer is preferably integrated into the thicker bottom foil, since the lid foil is formed in a transparent manner in order to enable the consumer to view the packaged goods through the lid foil. The thicker base films can be present, for example, as deep-drawn packages and be with

Filled with food or other packaged goods and then sealed with the thinner lidding film in the so - called FFS process (FORM - FILL - SEAL).

The subject of a further embodiment of the invention is also a method for producing a peelable, biodegradable first film arrangement, wherein

a first mixture for the preparation of the above-described peel layer comprising a polyhydroxycarboxylic acid and at least 25% by weight of a biodegradable polyester together with

a second mixture of the polyhydroxycarboxylic acid and the plasticizer

- be co-extruded.

During coextrusion, the first and the second mixture are solidified on top of each other, in which case the first film arrangement already described above forms. If the layers or mixtures can not be readily joined, it may be possible to additionally work with preferably biodegradable adhesion promoters.

To form the two layers can also be used from the prior art known blowing or casting process.

Prefabricated mixtures of the biodegradable polyester and the polyhydroxycarboxylic acid can be used particularly advantageously, which lead to peel layers with particularly homogeneous peel behavior, as already explained above. In the following, various embodiments of the invention will be described in more detail for explaining the invention. All the layers described in the following figures contain, for example, polylactide from Nature Works®, which is marketed under the brand name PLA 2002D.

Show it:

Figure 1 shows a seven-layered embodiment of a

according to the invention in cross section, which was produced by means of a casting process,

Figure 2 shows a cross section through a five-layered

Embodiment of a first film arrangement according to the invention, which was produced by means of a blowing method,

FIG. 3 shows an embodiment of a device according to the invention

Packaging in cross-section, in which one

Foil assembly according to the invention is sealed as a cover sheet with a Polylactidbodenfolie.

Figure 1 shows an example of an embodiment of a

Inventive first film assembly 1, which was prepared by a casting process. This is a first

Film layer 5A and an identical further film layer 5B containing 10% by weight of the plasticizer PEG 35000, 5% of a dye and 85% by weight of polylactide. The thickness of these layers is 70.5 ym. This first and the next

Film layers 5A and 5B flank a three-layer arrangement in the center of the film assembly 1, which is made up of two identical layers 6, which in turn are a central one

Flank foil layer 7. The two PLA film layers 6 consist of 92.5% by weight of PLA and 7.5% by weight of the

Plasticizer PEG 35000.

The thickness of the two Polylactidschichten 6 is 8 ym each. The central PLA-layer 7 has the same composition ^¬ reduction on how they framing PLA layers 6, wherein the thickness thereof is but 10 ym. The peel layer 10, which forms an outer layer, consists of 53.35% by weight of one

biodegradable esters, the ester Ecoflex® F BX 7011 from BASF and 3% by weight of a slip antiblock combination, Sukano® PLA DCS 511 and otherwise from PLA. The thickness of the peel layer 10 is 90 ym. The peel layer 10 is opposite the cover layer 20 as another outer layer, which has a thickness of 43 ym and 8.25% by weight of the plasticizer PEG 35000 and the remainder of PLA. Such a film has excellent when sealed with a PLA film

Sealing seam strengths in the range <15 N / 15 mm.

FIG. 2 shows in cross-section a further embodiment of a first film arrangement according to the invention, which is shown in FIG

Blowing process was prepared. This film arrangement has a first film layer 5A, which is 15% of the

Plasticizer PEG 35000 and the rest of PLA with a thickness of 8.34 ym and is flanked by more

Film layers 5B, which have an identical composition to the layer 5A, but are somewhat thinner. The

Peel layer 10 consists of 53.9% by weight of the biodegradable polyester and 2% by weight of the slip antiblock combination

Sukano® PLA DCS 511 and consists of the rest of PLA (thickness 12.5 ym). In contrast, there is the cover layer 20, which consists of 98% by weight of PLA and 2% of the already mentioned slip-antiblock combination and also has a thickness of 12.5 ym. These two film arrangements are at 100 ° C and a pressure of 6 bar for 0.5 s with the peel layer against

Laminated films sealed, their outer layers

have only PLA and the aforementioned slip antiblock combination, wherein in the film assembly of Figure 1, a peel value of 5.8 N / 15 mm and in the

Foil arrangement according to Figure 2, a peel of 3.5 N / 15 mm was measured.

Figure 3 shows a peelable, biodegradable Ver ^¬ package 30 in which a film arrangement according to the invention 1, which includes a peel layer 10 composed of polylactide and the biodegradable polyester, and further comprising a further PLA layer 5 as the first film layer, as the top foil was sealed against a lower film 2, a pure PLA film layer 5 and further a

Cover layer 20 has. Inside the package is in the cavity 4 packaged 40, for example a

Food. Such a package 30 is on the one hand tight and allows reliable storage of the

Packaged good 40, but on the other hand allows easy opening of the upper film 1 relative to the lower film 2. Furthermore, it is possible that the peel layer 10, in contrast to Figure 3 is not integrated into the upper film 1, but in the lower film 2. Such a package, in contrast to packaging materials of the prior art

Advantage that for sealing only one instead of two

Peel layers are necessary.

In the following experimentally determined seal ^¬ strengths in N / 15 mm are to be tabulated from the first film arrangements to composite films. It will the peel layer of the first film arrangement is sealed in each case against a pure PLA layer of the composite films under the standard conditions already mentioned above. Indicated in each case is the composition and thickness of the peel layer (in the line) as well as the thickness and nature of the pure PLA layer (in the associated column).

For comparison, the seal seam strengths of pure PLA layers are given against other PLA layers which do not comprise the peel layer according to the invention. PE = biodegradable polyester Ecoflex® F BX 7011, registered in the form of Ecovio® L BX 8145 or Ecovio F blend A 2224; PLA = polylactide; SAK = Slip antiblock combination.

Table 1 :

PLA layers of 12.5 ym; 98% 36 ym; 98% composite films PLA; 2% SAK PLA; 2% SAK

Peel layers of

The film system

90 ym; 43.65% PLA; 53.35% PE; 5, 8

3% SAK

100 ym; 43.65% PLA; 53.35% 4.4

PE; 3% SAK

7 ym; 44.1% PLA; 53.9% PE; 2% 3.5

SAK

12.5 yards; 44.1% PLA; 53.9% PE; 3.5

2% SAK

12.5 yards; 55.1% PLA; 42.9% PE; 12, 8

2% SAK 12.5 yards; 84.25% PLA; 13.75% 19, 7 PE; 2% SAK

12.5 yards; 92.5% PLA; 5.5% PE; 20.5

2% SAK

Comparative Examples with

Seals PLA foil against

PLA film

12.5 yards; 98% PLA; 2% SAK 25, 9

It can be clearly seen that in a seal of a peel layer according to the invention with at least 25% by weight of the biodegradable polyester against a PLA film good to very good seal seam strengths and excellent

Opening characteristics can be achieved when used for packaging. So are packaging systems with

Sealing seam strengths with values of 3.5, 4.4 and 5.8 N / 15 mm - as stated in the examples - on the one hand completely tight and protect the packaged goods, on the other hand, the

Packaging but very easily and with little effort to open nondestructively and without the aid of tools. In the example according to the invention with a

Sealing seam strength of 12.8 N / 15 mm - which was set by slightly reducing the biodegradable polyester Ecoflex F BX 7011 - the opening of the packaging is slightly more difficult, but still possible without any problems.

If less than 25% by weight of the biodegradable polyester is present in the peel layer, the seal seam strengths increase sharply. A package is in this case only very difficult to open, which does not meet the consumer. When sealing a pure PLA film against another PLA film, the seal seam strengths increase even further. In the latter case, sealing seam strengths significantly greater than 20 N / 15 mm are also referred to as "fixed closure". To open a considerable effort is possible, so that a nondestructive removal of the lid film is then no longer possible. In most cases, opening is only done with the aid of tools such as knives or scissors.

In the following, the seal seam strengths of film arrangements with a peel layer and a barrier layer against other PLA layers are shown which are not the

Peel layer according to the invention comprise. The barrier layers are each flanked by 18 ym thick primer layers on both sides containing Bynel® 21 E 830. The abbreviations are the same as already described in connection with Table 1

Table 2:

PLA layer of 12.5 ym; 98% PLA; 2%

Composite films SAK

Peel layers and

Barrier layers of the 1.

The film system

Peel layer: 70 ym; 43.65% PLA; 3, 9

53.35% PE; 3% SAK; Barrier layer:

8ym; 100% Soarnol® DC 3212B

Peel layer: 80 ym; 43.65% PLA; 4.1

53.35% PE; 3% SAK; Barrier layer:

15 ym 100% Soarnol® DC 3212B Table 2 can be deduced that even fiction, ^¬ contemporary variants of the peelable Folienanordung can achieve very good seal ^¬ strengths with a peel and a barrier layer.

Claims

claims

1. Peelable, at least 50% biodegradable

Foil arrangement (1) with a sealed seam strength of less than 15 N / 15 mm against a polyhydroxycarboxylic acid layer, with at least:

a first film layer (5A) ^comprising a polyhydroxy carboxylic acid and a plasticizer, and

- A peel layer (10), which is a mixture of a

Polyhydroxycarboxylic acid and at least 25% by weight, based on the peel layer of a biodegradable from the polyhydroxycarboxylic different polyester and the peel layer comprises an outer layer of

Foil assembly (1) forms.

2. A film assembly (1) according to claim 1, wherein the plasticizer is selected from glycerol, citric acid esters and polyalkylene glycols or any mixture of these plasticizers.

3. film assembly (1) according to one of the preceding

Claims, wherein the plasticizer is a polyalkylene glycol having a molecular weight of at least 1000.

4. film assembly (1) according to one of the preceding

Claims, wherein the plasticizer is polyethylene glycol, in particular polyethylene glycol 35000.

5. film assembly (1) according to one of the preceding

Claims,

wherein the plasticizer is present in a proportion of 5 to 20% by weight in the first film layer.

6. A film assembly according to any one of the preceding claims, wherein the polyhydroxycarboxylic acid is a polylactide.

7. film assembly (1) according to one of the preceding

Claims, wherein the biodegradable polyester is formed by polymerization of a mixture consisting of:

Adipic acid, its ester-forming derivatives, or

Mixtures thereof,

Terephthalic acid, its ester-forming derivatives, or mixtures thereof, and

C2 to e alkanediols, C ₅ -C ₁₀ cycloalkanediols, or mixtures thereof,

can be produced.

8. film arrangement (1) according to the preceding claim,

wherein the biodegradable polyester is present in a proportion of 40 to 80% by weight in the peel layer.

9. film assembly (1) according to one of the preceding

Claims,

wherein the peel layer (10) is free of adhesion promoters or adhesives.

10. film assembly (1) according to one of the preceding

Claims, additionally comprising:

at least one further film layer (5B) comprising a polyhydroxycarboxylic acid with a plasticizer and disposed on the first film layer (5A).

11. Foil arrangement (1) according to the preceding claim, wherein the first film layer (5) located in the interior of the film arrangement has a higher proportion Having plasticizer, as the further outward at least one further film layer (15).

12. Foil arrangement (1) according to the preceding claim,

in which

the film layers (5, 15) and / or the peel layer (10) contain additives, such as, for example, dyes.

13. Foil assembly (1) according to one of the preceding

Claims, additionally comprising:

a cover layer (20) as a further outer layer, wherein the cover layer contains a polyhydroxycarboxylic acid.

14. Foil arrangement (1) according to the preceding claim,

in which

the cover layer (20) contains a plasticizer whose proportion of the cover layer (20) is lower than the proportion of the plasticizer on the first film layer (5).

15. Foil arrangement (1) according to one of the preceding

Claims, additionally comprising

a barrier layer at least against oxygen and / or water.

16. Film arrangement according to the preceding claim, wherein the barrier layer has a permeability of <10,

preferably <5, more preferably <2 g / m ^{2 »} day for water and a permeability of <10, preferably <5

cm ³ / m ^{2 »} day for oxygen.

17. Folienanordung according to any one of the preceding claims 15 or 16, wherein the barrier layer comprises a polymer selected from: polyamide, polypropylene, polyethylene, cycloolefin copolymer and ethylene-vinyl alcohol copolymer and mixtures thereof.

18. Film arrangement according to one of the preceding claims 15 to 17, additionally comprising:

a primer layer between the

Barrier layer and the first film layer (5A) is arranged.

19. Peelable, at least 50% biodegradable

Packaging (30), comprising:

a first film assembly (1) having a first

A film layer (5A) containing a polyhydroxycarboxylic acid and a peel layer (10) comprising a mixture of a polyhydroxycarboxylic acid and at least 25% by weight, based on the peel layer, of a biodegradable one different from the polyhydroxycarboxylic acid

Includes polyester, and

a second sheet (5B), comprising a polyhydroxy ^¬ carboxylic acid which is free from the biologically

degradable polyester,

wherein the peel layer (10) of the first film assembly (1) against the second film (5B) with a

Sealed seam strength of less than 15 N / 15 mm is sealed.

20. Packaging according to the preceding claim, wherein

the polyhydroxycarboxylic acid of the first film assembly and the polyhydroxycarboxylic acid of the second film are the same.

21. A package according to any one of claims 19 or 20, wherein the polyhydroxycarboxylic acid is a polylactide.

22. Packaging according to one of claims 19 to 21, wherein

a plasticizer is present in the first film layer of the first film arrangement.

23. Packaging according to one of claims 19 to 22, wherein

the seal at a temperature of 80 ° C to 120 ° C at a pressure of 0.5 bar to 10 bar for a

Time span of 0.5 s to 10 s has occurred.

24. Packaging according to one of claims 19 to 23, wherein

the first film arrangement (1) and / or the second film comprises a barrier layer.

25. Process for the preparation of a peelable, at least to

The 50% biodegradable film assembly of any one of claims 1 to 18, wherein a first mixture comprising the polyhydroxycarboxylic acid and at least 25% by weight of a biodegradable polyhydroxycarboxylic acid-dissimilar polyester is co-extruded together with a second mixture comprising a polyhydroxycarboxylic acid and a plasticizer the first film layer (5A) and the peel layer (10) are formed.

26. Method according to the preceding claim, in which

the first and second mix in the blow or

Casting process be co-extruded.

27. The method according to any one of the preceding claims 25 or

26, where as a first mixture a prefabricated mixture of

Polyhydroxycarboxylic acid and the biodegradable of the polyhydroxycarboxylic acid of different polyester is used.

A method according to any one of the preceding claims, wherein additionally a polymer material for the barrier layer is coextruded.

29. A process for producing a peelable, at least 50% biodegradable film arrangement according to one of claims 1 to 18, wherein between the first

Foil layer (5A) and the peel layer (10) a

Barrier layer is formed by lamination.