KR20010041920A - Thermoplastic Polyester Amide Films Made of at least Two Layers and with Improved Sealing Properties, Method for Producing Same and Their Use - Google Patents

Abstract

The present invention relates to a multilayer film made of several polyester amides having different molecular structures. The polyester amides are biodegradable so that the entire multilayer film is also biodegradable. The multilayer film can be unoriented and oriented uniaxially or biaxially. To make it easier to process it may contain additives and have improved sealing properties.

Description

Thermoplastic Polyester Amide Films Made of at least Two Layers and with Improved Sealing Properties, Method for Producing Same and Their Use}

The present invention relates to a thermoplastic film of polyester amide having two or more layers.

Thermoplastic films of polyester amides are known, for example, from DE-A-44 44 948 or DE-A-196 32 799 (as part of a composite multilayer film). However, such single layer films have inadequate sealing properties, in particular inadequate sealing strength, in many applications.

Therefore, it is an object of the present invention to produce polyester amide films with improved sealing properties. This object was achieved by making films with two or more layers of several polyester amides with different molecular structures and different high temperature properties. Two or more layers in this film are arranged such that the outer layer of polyester amide has a lower melting point than the inner layer directly adjacent to it. Each layer may consist of a single polyester amide or a mixture of several polyester amides. For the purpose of better manufacturing or better processing, the film may additionally be added with conventional additives and auxiliary materials. Films having two or more layers are preferably produced using an extrusion process. Additionally, uniaxial or biaxial orientation may be performed on the film having two or more layers.

Surprisingly, polyester amides can be thermoplastically processed and improved sealing properties are achieved as a result of two or more layer structures of different polyester amides in the case of unstretched, uniaxially or biaxially stretched films. The improved sealing properties of stretched and unstretched films have less strain on the seal joints compared to single layer films, and are remarkable for high seal joint strength.

It is advantageous that the inner layer directly adjacent to the outer layer has a higher content of polyamide structure than the outer layer.

According to the invention, particular preference is given to films of a three-layer structure having a lower melting point than the inner layer directly adjacent to the outer layer, in particular with an additional inner layer (ie a third layer) having the same composition as the outer layer.

The present invention has two or more layers, all of which can be unextended, uniaxially or biaxially stretched, said layers consisting of different polyester amides or mixtures of several polyester amides, and in addition to one, one or more or the entire layer. Up to 5% by weight of nucleating agents, up to 5% by weight of conventional stabilizers and neutralizing agents, up to 5% by weight of conventional lubricants and release agents, and preferably up to 5% by weight of conventional block inhibitors in the outer top layer It provides a film containing.

In certain forms, the film having two or more layers may be further surface treated with corona and / or flame and / or plasma pretreatment, and / or may be added / deposited with oxidizing materials and / or Mixtures of substances and / or oxidation and / or which may be added, for example ozone or plasma excited gas mixtures such as hexamethyldisiloxane and nitrogen (N ₂ ) and / or oxygen (O ₂ ) It can be treated with a gas having a radical component such as a mixture of In the case of stretched films, the mentioned surface pretreatment is preferably carried out after orientation.

Uniaxial or biaxial orientation takes place at temperatures above the glass transition temperature for amorphous thermoplastics and at temperatures above the glass transition temperature and below the crystal melting temperature for partially crystalline thermoplastics.

It is known that not only certain polyester amides but also other polymeric materials can undergo biodegradation. Materials which may be mentioned in this regard are mainly obtained from polymers which occur naturally directly or after modification, for example polyhydroxybutyrate, plastic cellulose, cellulose esters, plastic starch, chitosan and pullulan Hydroxy alkanoate. Certain modifications of the preferred polymer composition or structure in terms of the use of the polymer are difficult and only possible to a very limited extent according to natural synthetic methods. Within the scope of the present invention, the expression "biodegradable and degradable polymers and films" is understood to mean materials which are biodegradable when tested in an experiment according to DIN V 54900 of 1998.

On the other hand, many synthetic polymers are not attacked by microorganisms or are only very slowly attacked. Synthetic polymers containing heteroatoms in the main chain are often considered to be potentially biodegradable. Polyester is shown as an important type in these materials. Synthetic raw materials containing only aliphatic monomers exhibit relatively good biodegradability, but they can only be used to a very limited extent because of their material properties (see Witt et al., In Macrom. Chem. Phys., 195 (1994) p. 793-802). Aromatic polyesters, on the other hand, have good material properties while exhibiting significantly poor biodegradability.

Various biodegradable polymers have been known recently (see DE-44 32 161). They can be easily thermoplastically processed and, on the other hand, have biodegradable properties, ie their entire polymer chains are cleaved by enzymes by microorganisms (bacteria and fungi) and completely decomposed into carbon dioxide, water and biomass. . The corresponding experiments in the natural environment under the action of microorganisms such as those found in compost are given in DIN V 54 900. Given their thermoplastic properties, these biodegradable materials can be processed to form semi-finished products such as mold films or blowing films. Nevertheless, the use of such semi-finished products is very limited. On the one hand such films are distinguished by poor mechanical properties and the barrier properties associated with water vapor and gas are very poor compared to films of biodegradable plastics such as conventional polyethylene, polypropylene or polyamide.

The invention also relates to the use of certain biodegradable and corrosive polyester amides or mixtures of these polymers in the production of multilayer films.

According to the invention, aliphatic or partially aromatic polyester amides consisting of the following monomers are suitable.

I) aliphatic dihydric alcohols, for example ethanediol, butanediol, hexanediol, especially butanediol, preferably linear C ₂ to C ₁₀ dialcohols, and / or optionally for example cyclohexanedimethanol Preferably a molecular weight of 4000 or less, preferably 1000 or less, based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers thereof in place of some or all of the alicyclic dihydric alcohols having 5 to 8 carbon atoms, and / or diols Small amounts of monomeric or oligomeric polyols, and / or optionally branched dihydric alcohols such as for example neopentyl glycol, preferably C ₃ -C ₁₂ -alkyldiol and additionally for example 1,2,3-propanetri Not only a small amount of a high functional alcohol such as trimethylolpropane, preferably a C ₃ -C ₁₂ -alkylpolyol, but also preferably an alkyl chain such as succinic acid or adipic acid. Small aliphatic diacids of 12 to 12, and / or optionally aromatic diacids such as for example terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and additionally optionally small amounts of high functional acids such as trimellitic acid, or

II) Acid- and alcohol-functionalized structures, preferably having 2 to 12 carbon atoms in the carbon chain, such as, for example, hydroxybutyric acid, hydroxyvalleic acid, lactic acid or derivatives thereof, such as caprolactone or dilactide Unit, or

Mixtures and / or copolymers of I) and II), wherein the aromatic acid is in an amount of up to 50% by weight, based on the total acid, and

III) aliphatic and / or cycloaliphatic divalent and / or any small amounts of branched chain divalent amines (wherein linear aliphatic C ₂ to C ₁₀ -diamines are preferred), and additionally any small amount as the amide component Highly functional amines, preferably hexamethylenediamine, isophoronediamine and especially hexamethylenediamine, as well as linear and / or alicyclic divalent acids having 2 to 12 carbon atoms in the alkyl chain, or alicyclic acids. , Preferably in the case of adipic acid, a C ₅ to C ₆ ring, and / or any small amount of branched chain divalent and / or optionally aromatic divalent acids, for example terephthalic acid, isophthalic acid, naphthalenedicarboxyl The amide component of an acid, and further optionally a small amount of a highly functional acid of 2 to 10 carbon atoms, or

IV) acid- and amine-functionalized structural units, preferably having 4 to 20 carbon atoms in the alicyclic chain, preferably amide components of ω-laurinlactam, ε-caprolactam, in particular ω-caprolactam,

Or a mixture of III) and IV), wherein the ester component of I) and / or II) is at least 3% by weight based on the sum of I), II), III) and IV), and I), II The ester structure is preferably in an amount of 5 to 70% by weight, the amide structure is preferably in an amount of 95 to 30% by weight, and the biodegradable polyester amide of the preferred form, based on the sum of The ester components I) and / or II) are at least 30% by weight, the amount of ester structure is preferably 30 to 70% by weight and the amount of amide structure is preferably 70 to 30% by weight.

Suitable polyester amides according to the invention may be a mixture of pure polyester amides and various polyester amides.

Suitable polyester amides according to the invention are nucleating agents commonly used in the case of polyesters (eg 1,5-naphthalenedisosulfonate or silicate layers such as talcum, or nanoparticle sizes ie less than 1 μm on average). Nucleating agents such as titanium nitride, aluminum hydroxide hydrate, barium sulfate or zirconium compounds having a particle size) up to 5% by weight, up to 5% by weight of conventional stabilizers and neutralizers, up to 5% by weight of conventional lubricants and release agents, and conventional May contain up to 5% by weight of an antiblocking agent and may be surface treated with corona, flame or plasma pretreatment, or a substance or mixture of substances, such as ozone or a plasma excited gas mixture, such as hexamethyldi It can be treated with a gas having a radical component such as a mixture of siloxane and nitrogen (N ₂ ) and oxygen (O ₂ ).

As stabilizers and neutralizers, compounds having a stabilizing action commonly used in the case of polyester compounds can be used. Its addition amount is 5% by weight or less.

Especially preferred as stabilizers are phenolic stabilizers, alkali metal / alkaline earth metal stearates and / or alkali metal / alkaline earth metal carbonates. The amount of phenolic stabilizer is preferably 0 to 3% by weight, in particular 0.15 to 0.3% by weight and has a molar mass of at least 500 g / mol. Pentaerythritol tetrakis-3 (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate or 1,3,5-trimethyl-2,4,6-tris- (3,5- Di-tert-butyl-4-hydroxybenzyl) -benzene is particularly advantageous.

The neutralizing agent is preferably dihydrotalcite, calcium stearate, calcium carbonate and / or calcium montanate having an average particle size of 0.7 μm or less, an absolute particle size of less than 10 μm, and a specific surface area of 40 m ² / g or more. .

In a particularly preferred embodiment of the film, the nucleating agent content is from 0.0001 to 2% by weight and the stabilizer and neutralizer content is from 0.0001 to 2% by weight.

Lubricants and release agents are higher aliphatic amides, tertiary amines, aliphatic acid amides, higher aliphatic acid esters, low molecular weight polar modified waxes, montan waxes, cyclic waxes, phthalates, metal soaps and silicone oils. Addition of higher aliphatic acid amides and silicone oils is particularly suitable.

Of the aliphatic amides, commercial forms of ethylene amide to stearyl amide are particularly suitable. Aliphatic acid amides are amides of water-insoluble monocarboxylic acids (so-called fatty acids) having 8 to 24 carbon atoms, preferably 10 to 18 carbon atoms. Of these, erucic acid amide, stearic acid amide and oleic acid amide are preferred.

Also suitable are compounds containing both ester groups and amide groups as release agents or lubricants, such as stearamide ethyl stearate or esteramido-ethyl stearate.

The term "montane wax" includes many different compounds. In this regard, reference is made to Neumueller et al. In Roempps Chemie-Lexikon, Franckh'sche Verlagshandlung, Stuttgart, 1974.

As the cyclic wax, for example, components such as adipic acid, tetramethylene ester and 1,6-dioxa-2,7-dioxocyclododecane, or hexamethylene cognate derivatives are suitable. Such materials are known from commercial products under the trade name Glycolube VL.

Suitable silicone oils are polydialkylsiloxanes, preferably polydimethylsiloxanes, polymethylphenylsiloxanes, olefin modified silicones, silicones modified with polyesters, for example polyethylene glycols and polypropylene glycols as well as epoxyamino- and alcohol-modified Silicon. Suitable silicone oils have a viscosity in the range of 5,000 to 1,000,000 mm ² / s. Preference is given to polydimethylsiloxanes having a viscosity of 10,000 to 100,000 mm ² / s.

The amount of lubricant added is 5% by weight or less. In a particularly preferred embodiment of the film, the lubricant content is from 0.005 to 4% by weight. In a very particularly preferred embodiment of the film, the lubricant content is from 0.05 to 1% by weight.

Suitable blockers are both inorganic and organic additives that protrude from the surface of the film as bumps, creating a spacer effect.

In the preferred form, the following materials are used as inorganic block inhibitors.

Aluminum hydroxide

Aluminum silicate, for example kaolin or kaolin clay

Aluminum oxide, for example O-aluminum oxide

Aluminum sulfate

Ceramic of Silica-Aluminum Oxide

Barium sulfate

Natural and synthetic silica

Silicate layer, for example asbestos

Silicon dioxide

Calsite type calcium carbonate

Calcium phosphate

Magnesium silicate

Magnesium carbonate

Magnesium oxide

Titanium dioxide

Zinc oxide

Glass microspheres.

The following materials, such as organic polymers which are incompatible with biodegradable polymers, are used as organic block inhibitors.

Starch

polystyrene

Polyamide

Polycarbonate

Crosslinked and Uncrosslinked Polymethyl Methacrylate

Crosslinked polysiloxanes (eg, Tospearl)

Polar modified polyethylene (eg, maleic anhydride conjugated polyethylene)

Polar modified polypropylene (eg, maleic anhydride conjugated polypropylene)

Random copolymers based on metal salts of ethylene or propylene with vinyl alcohol, vinyl acetate, acrylic acid, acrylic esters, methacrylic acid, methacrylic acid esters, methacrylic acid, or metal salts of methacrylic acid esters

Benzoguanamine-formaldehyde polymer

Aliphatic and partially aromatic polyesters having different melting points than the raw materials of the film

Aliphatic polyester amides having different melting points than the raw materials of the film

Aliphatic Polyester Urethanes with Melting Point Different from Raw Material of Film

Aliphatic-aromatic polyester carbonates having a melting point different from the raw material of the film.

The effective amount of the block inhibitor is 5% by weight or less. In a particularly preferred embodiment, the film comprises from 0.005 to 4% by weight of antiblocking agent. In a very particularly preferred embodiment, the film comprises 0.05 to 1% by weight of antiblocking agent. As described in EP-A--0 236 945 and DE-A-38 01 535, the average particle size is 1-6 μm, in particular 2-5 μm, spherical particles being particularly suitable. Also suitable are combinations of different spacer systems. In a particularly preferred embodiment, a spacer system is added to the outer top layer.

According to the method used herein, the polymer of the film to which the additive has been added contains a preferred amount of organic or inorganic filler during the preparation of the raw material. In the case of granulation of the raw material, for example in a twin screw extruder, an additive is added to the raw material. In addition to the type of additive addition, it is also possible that some or all of the required additives are added in the form of a masterbatch free or only partially contained. Within the scope of the present invention, the term "masterbatch" is a plastic raw material of stock mixtures, in particular granular, dust-free concentrates containing a large amount of additives, for the preparation of a composition for producing a film containing a certain amount of additives ( Is used as an intermediate in the addition of a substance to granules containing no additives or only partially or incompletely containing additives. Before the polymer granules are introduced into the extruder, the masterbatch is added to the raw material containing no additives or only partially or incompletely containing additives in an amount to achieve the desired weight of filler in the film.

Preferred materials for which the master batch is prepared in addition to the additives are materials compatible with the polyester amides mentioned in the present invention.

In addition to the additives as a subgroup of biodegradable polyester amides, the material from which the master batch is made is in a particularly preferred form, similarly biodegradable.

In corona treatment, the film passes between two conductor elements acting as electrodes, where a high voltage of an alternating voltage (approximately 5 to 20 kV and 5 to 30 kHz) is applied between the electrodes and spray or corona discharge is applied. It is advantageous to follow the procedures that can occur. Air on the film surface is ionized by spraying or corona discharge, and reacts with molecules on the film surface to form additional polar introduction into the polymer matrix.

In the case of flame treatment with polarized flames (see US-A-4 622 237), a current voltage is applied between the combustor (cathode) and the cooling roller. The voltage level applied is 400 to 3000 V, preferably 500 to 2000 V. With the application of voltage, ionized atomic acceleration is increased to impinge on the surface with large mechanical energy. Chemical bonds in polymer molecules break more quickly, and radical formation proceeds more rapidly. In this case the high temperature stress on the polymer surface is much less than in the case of standard flame treatments, and it is possible to obtain a film whose sealing properties of the treated side are much better than those of the untreated surface.

In the case of plasma pretreatment, gases such as oxygen, nitrogen, carbon dioxide, methane, halogenated hydrocarbons, silane compounds, high molecular compounds, or mixtures thereof are exposed to a high energy field, for example microwave radiation, in a low pressure chamber. When high-energy electrons form, they collide with molecules and transfer their energy. As a result, the plasma itself is actually room temperature, but the radical structure is locally formed in an excited state corresponding to thousands of degrees Celsius. As a result, it breaks down the chemical bonds and starts a kinetic action that can normally occur only at high temperatures. Monomer radicals and ions are formed. In some cases, short chain oligomers are formed from the monomer radicals generated even in the plasma, and condensed and polymerized on the surface to be applied. Thus, a uniform film is deposited on the material to be applied.

However, it is also possible to add additional streams of material to the so-called afterglow zone of excited molecules before the monomer radicals or ions are deposited on the support. In this way it is possible to prepare a substance or mixture of substances that impinge on the surface of the polymer film and create an oxidative attack on the support polymer. Glass-like and in most cases highly crosslinked layer forms are firmly bonded to the film surface. Suitable material compositions increase the surface tension on the film.

According to the invention a film having two or more layers is advantageously produced using an extrusion process. The polyester amide in granular form is melted, homogenized, compacted and released through a multilayer die in an extruder. The die may be a ring die for the production of seamless tubular films. The film thus released or stretched, for example by a press roll, is then cooled until it solidifies. Cooling may be performed by air or water or additionally by a cooling roller. In the case of tubular films, cooling can occur on one or both internally and externally, or internally or externally only. In addition, the tubular film may be cut on one or both sides to obtain a multilayer unstretched flat film.

The tubular film produced as described above is adjusted as a main tube after cooling, in part to a temperature below the crystal melting temperature in the case of crystalline polyester amide, and to a temperature above the glass transition temperature in the case of amorphous polyester amide, Biaxially ideally stretches at the same time. A particularly suitable method is simultaneous biaxial stretching using the double bubble technique in which the expansion of the main bubble occurs by applied internal pressure. For certain adjustments of shrinkage properties, the film can then be heat treated. In this fixation process, the film can be heated again below the crystal melting temperature.

The tubular film is then subjected to internal or external surface treatment.

The invention also provides an extrusion process for the production of a multilayer film according to the invention in which the multilayer die is in the form of a sheet for the production of a multilayer flat film. The released film is then cooled until it solidifies. Cooling can be performed with water using a cooling roller.

After cooling, the flat film is adjusted to a temperature below the crystal melting temperature in the case of partially crystalline polyamide and stretched uniaxially or biaxially one or more times after adjusting to a temperature above the glass transition temperature in the case of amorphous polyamide Can be. After each stretching step, the fixation of the film can optionally be performed. After stretching and possibly a fixing step that may occur, the finished film may optionally be subjected to an inline surface pretreatment.

The invention also provides a method for uniaxial or biaxial stretching according to the invention. Biaxial stretching is a simultaneous stretching method, or a two-step continuous method in which the kidneys first and then laterally or laterally and then laterally, or kidneys first and laterally and finally laterally or firstly. A three-step continuous method whereby then to species and finally to transverse, or kidneys first to species then laterally, laterally and finally laterally or first laterally laterally and laterally and finally laterally It can be carried out by a four-step continuous method. Fixation of the film may optionally occur after each stretching operation. The stretching operation in each longitudinal and transverse direction can be carried out in one step or in several steps.

In a preferred form, biaxial stretching according to the invention is characterized in that it is a sequential method starting with longitudinal stretching.

In a preferred form, the uniaxial stretching of the film according to the invention is characterized in that the stretching ratio in the longitudinal direction is from 1: 1.5 to 1:10.

In another preferred form, the uniaxial stretching of the film according to the invention is characterized in that the stretching ratio in the longitudinal direction is from 1: 2.8 to 1: 8.

In another preferred form, the biaxial stretching of the film according to the invention is characterized in that the total stretching ratio in the longitudinal direction is from 1: 1.5 to 1:10 and the total stretching ratio in the lateral direction is from 1: 2 to 1:20.

In another preferred form, the biaxial stretching of the film according to the invention is characterized in that the total stretching ratio in the longitudinal direction is 1: 2.8 to 1: 8 and the total stretching ratio in the lateral direction is 1: 3.8 to 1:15.

In a preferred form of the film according to the invention, the thickness is less than 500 μm.

In another preferred form of the film according to the invention, the thickness is less than 80 μm. Thus, it is advantageous that the outer layer is smaller in thickness than the inner layer directly adjacent thereto. Particularly preferably, the thickness of the outer layer is 5-20 μm, and the thickness of the inner layer adjacent thereto is 20-40 μm. The thickness of the subsequent inner layer which may optionally be present is preferably 5 to 20 μm.

The invention also relates to the use of the film according to the invention. Contemplated uses include multilayer films in printed, unprinted or colored form as well as pretreated or unpretreated forms for packaging in the field of food or nonfood materials; As multilayer films in pretreated or unpretreated form for protection and separation purposes in connection with cosmetics and hygiene articles, for example infant diapers or sanitary towels; As a pretreated or unpretreated multilayer film for surface protection or surface refining in the field of card, paper and character window linings; It is a pre- or untreated form, a printed or non-printed form, as well as a refined film that can be provided with an adhesive and used as a label or adhesive strip.

Multilayer films of biodegradable polyester amides are also not pretreated or pretreated for greenhouse cover or mulch films in the horticulture or agricultural sector, or for the storage and transportation of materials such as biowaste when finished to form bags. It can be used in unformed form, and the decomposition rate can be adjusted by the multilayer structure, the orientation of the molecules / crystals, and the coloring / printing. Moreover, good permeability of multilayer films of different polyester amides to oxygen, carbon dioxide and water vapor is particularly important for the packaging of fresh foods. The biodegradability of certain polyester amides may be particularly beneficial for certain applications.

In order to improve the adhesion of printing or adhesives, the surface of the film during its manufacture and / or during subsequent processing may be formed of corona, flame, plasma or another oxidizing material or mixtures thereof, such as ozone or plasma excited gases. The mixture may be pretreated in such a way that an increase in surface tension is produced by a gas having a radical component such as a mixture of hexamethyldisiloxane and nitrogen (N ₂ ) and / or oxygen (O ₂ ).

The invention also relates to the use of the multilayer film according to the invention as a coated film or film composite. Other films of the composite may be non-degradable or biodegradable films and corrosive films. In addition, the coating materials or adhesives used may belong to both common non-degradable systems and to biodegradable and corrosive raw materials.

In a particularly preferred form of use of the multilayer film according to the invention, only those materials in which the composite as a whole can be similarly biodegradable and corrosive in accordance with DIN V 54 900 during the production of coated films or film composites are used.

The invention also relates to the use of the multilayer film according to the invention as a starting material for the production of bags which release their contents after degradation by the process of biodegradation. The bag may be made by sealing as well as bonding of films, and may be made to have an opening that is sealed or has a suitable seal or connector.

The invention also provides a multilayer film or composite according to the invention as a starting material for producing a packaging film, separation film or surface protective film having very high water vapor permeability by puncturing the film with a cooled or temperature controlled needle roller of the film. It relates to the use of. Such films are used for the packaging of moisture-releasing articles such as bread or various types of fruits and vegetables, or as separation and protective films in the field of hygiene.

<Example 1>

Two layer films of structure AB were made from two different polyester amides belonging to a subgroup of biodegradable polyester amides in terms of their structure. Material A (polyester amide consisting of 54 wt% ε-caprolactam, 23 wt% adipic acid, 60 wt% amide structure with 23 wt% 1,4-butanediol and 40 wt% ester structure, Bayer LP BAK 403-004 of AG has a MFI of 7 (g / 10 min at 190 ° C., measured according to DIN 53 735 at 2.16 kg), melting point of 125 ° C., 1% by weight, according to ISO 3146 / C2. Lubricant content and block inhibitor content of 0.1% by weight. Material B (polyester amide consisting of 62 wt% ε-caprolactam, 29 wt% adipic acid, 17 wt% 1,4-butanediol, 65 wt% amide structure and 35 wt% ester structure, Bayer AG's LP BAK 404-002) has a MFI of 10 (g / 10 min at 190 ° C., measured according to DIN 53 735 at 2.16 kg), melting point of 140 ° C., 0.4% by weight according to ISO 3146 / C2. Lubricant content and block inhibitor content of 0.1% by weight. The two layers of film were coextruded and subsequently stretched biaxially. The maximum extrusion temperature was 180 ° C. for material A and 190 ° C. for material B. The melt was cooled with a flat film on a roller temperature of 43 ° C. of the mold roller and a cooling roller frame of 22 ° C. of the cooling roller. The solid thick film thus formed was heated to extension temperature in the subsequent step using a roller adjusted to 82 ° C. The actual stretching roller was performed at a temperature of 85 ° C. The flat film was stretched in one step at a ratio of 1: 4.2 in the longitudinal direction. The heating roller then has a temperature of 50 ° C. after the film passes. The preheat zone of the transverse oven was adjusted to a temperature of 130 ° C. The temperature of the actual transverse section was 120 ° C. At that point the film was stretched transversely at a ratio of 1: 4.6. A theoretical area stretch ratio of 1: 19.3 was obtained. After transverse stretching, the film was fixed at a temperature of 105 ° C. The manufacturing speed at the exit of the transverse unit was 18.0 m / min. A film with a thickness of 55 μm can be obtained.

<Example 2>

The same biodegradable polyester amide of Example 1 was processed under the processing conditions described in Example 1 to produce three layers of biaxially oriented ABA films. In this case, a film having a total thickness of 80 μm was produced, and an outer layer was formed of a low melting polyester amide to achieve improved sealing properties of the film.

<Example 3>

Three layers of ABA films were prepared by blowing film equipment from the same biodegradable polyester amides of Examples 1 and 2. Maximum extrusion temperature was 160 ° C. The melt was discharged through a multilayer ring die and cooled using air. The maximum die temperature was similarly 160 ° C. In this case, a film having a total thickness of 75 μm was produced with a width of 500 mm, and an outer layer was formed from a low melting point polyester amide.

<Comparative Example>

Single layer films were prepared by blowing film equipment from the biodegradable polyester amides of Material 1, 2 and 3 (Material A). Maximum extrusion temperature was 160 ° C. The melt was discharged through the ring die and cooled with air. The maximum die temperature was similarly 160 ° C. In this case, a film having a total thickness of 95 μm was produced with a width of 300 mm.

The following physical properties were measured in the prepared samples as follows.

Mechanical properties

Tensile strength and elongation at break, which are mechanical values in both the longitudinal and transverse directions, were measured in accordance with DIN 53 455. Modulus of elasticity in the longitudinal and transverse directions was measured according to DIN 53 457. The thickness of each sample was measured according to DIN 53 370.

Transmission characteristics

Permeability to oxygen was measured in the samples at a temperature of 23 ° C. and a relative humidity of 75% according to DIN 53 380. In addition, permeability to water vapor was measured according to DIN 53 122 at a temperature of 23 ° C. and a relative humidity of 85%.

Sealing joint strength

The strength of the sealing joints produced on the sealing device with the sealing tool heated on both sides was measured on the sample. Seal strength is understood as the maximum force required to break a seal joint produced under limited conditions (pressure, time, temperature). The sealing joint is given by N and the strip width is added by the index (N / 15 mm). The sealing range is the temperature range given a measurable sealing strength.

Two complete clean test strips were removed from the width of the film to be tested. For sealing purposes, they are placed on surfaces to be sealed on top of each other so as to protrude at least 1 cm from each side and held between the sealing jaws. Sealing should be carried out perpendicular to the working direction of the film.

Seal strength experiments were performed according to the following standard conditions.

Pressure: 50 N / cm ²

Time: 0.5 seconds

Temperature: Starting from 150 ° C up to 10 K steps

A 15 mm wide experimental strip was cut from the center of the sealing joint made in the working direction of the film using an experimental strip cutter. Seal strength was tested by using a tensile test apparatus to be perpendicular to the seal joint. The maximum value of the force generated during tearing is given in each case.

Table 1 shows the experimental results for the samples from Examples 1, 2, 3 and Comparative Examples.

Example 1 Example 2 Example 3 Comparative example Mechanical property thickness (㎛) 56 77 74 95 Elastic modulus (MPa) 359 238 228 223 Modulus of elasticity (MPa) 216 384 215 244 Tensile Strength Class (MPa) 92 91 36 49 Tensile Strength Transverse (MPa) 82 86 34 51 Elongation at break (%) 156 228 620 765 Elongation at break (%) 165 171 716 854 Permeability Oxygen 23 ℃ / 75% rh (cm ³ / m ² / d / bar) 466 391 408 360 Water vapor 23 ° C / 85% rh (g / m ² / d) 145 107 122 100 Sealing strength required tearing force (N / 15 mm) Do not measure Do not measure 18 (at 150 ° C) 11 (at 150 ° C)

Claims (24)

Having at least two layers, said layers consisting essentially of at least one polyester amide, optionally up to 5% by weight of nucleating agent, 5% by weight, based on the total mass of the film in one, at least one, or the entire layer Further contains up to 5% by weight of conventional stabilizers and neutralizers, up to 5% by weight of conventional lubricants and mold release agents, and further containing up to 5% by weight of conventional antiblocking agents, wherein the outer polyester amide layer A thermoplastic film, having a lower melting point than a directly adjacent inner layer. The film of claim 1, wherein the inner layer directly adjacent to the outer layer has a higher content of polyamide structure than the outer layer. The method according to claim 1 or 2, wherein the polyester amide is I) aliphatic dihydric alcohols, for example ethanediol, butanediol, hexanediol, especially butanediol, preferably linear C ₂ to C ₁₀ dialcohols, and / or optionally for example cyclohexanedimethanol Preferably a molecular weight of 4000 or less, preferably 1000 or less, based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers thereof in place of some or all of the alicyclic dihydric alcohols having 5 to 8 carbon atoms, and / or diols Small amounts of monomeric or oligomeric polyols, and / or optionally branched dihydric alcohols such as, for example, neopentyl glycol, preferably C ₃ -C ₁₂ -alkyldiol, and additionally, eg 1,2,3-propane High functional alcohols such as triols, trimethylolpropane, preferably C ₃ -C ₁₂ -alkylpolyols, as well as preferably alkyl chains of 2 to 3 carbon atoms, such as succinic acid and adipic acid Any small amount of aliphatic diacid, which is 12, and / or optionally aromatic diacids such as for example terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and further optionally small amounts of high functional acids such as trimellitic acid, or II) Acid- and alcohol-functionalized structures, preferably having 2 to 12 carbon atoms in the carbon chain, such as, for example, hydroxybutyric acid, hydroxyvalleic acid, lactic acid or derivatives thereof, such as caprolactone or dilactide Unit, or Aliphatic or partially aromatic polyesters of mixtures and / or copolymers of I) and II) wherein the aromatic acid is in an amount of up to 50% by weight, based on the total acid, and III) aliphatic and / or cycloaliphatic divalent and / or optionally small amounts of branched chain divalent amines, where linear aliphatic C ₂ to C ₁₀ -diamines are preferred, and additionally small amounts of high functionality Amines, preferably hexamethylenediamine, isophoronediamine and especially hexamethylenediamine, as well as linear and / or cycloaliphatic divalent acids having 2 to 12 carbon atoms, preferably alkyl chains, or cycloaliphatic acids, preferably Adipic acid, a C ₅ to C ₆ ring, and / or any small amount of branched chain divalent and / or optionally aromatic divalent acids, such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and additionally Preferably the amide component of any small amount of high functional acid of 2 to 10 carbon atoms, or IV) amide components of acid- and amine-functionalized structural units, preferably of 4 to 20 carbon atoms, preferably of ω-laurinlactam, ε-caprolactam, in particular ω-caprolactam, Or as an amide component the mixture of said III) and IV), wherein the ester component of components I) and / or II) is at least 3% by weight based on the sum of I), II), III) and IV), Based on the sum of I), II), III) and IV) the ester structure is preferably in an amount of 5 to 70% by weight, the amide structure is preferably in an amount of 95 to 30% by weight, and in a preferred form of biodegradability Ester component I) and / or II) with polyester amide is at least 30% by weight, the amount of ester structure is preferably 30 to 70% by weight and the amount of amide structure is preferably 70 to 30% by weight) Characterized in that the polyester amide film. The film according to claim 1, wherein the polyester amide can be both a pure polyester amide and a mixture of different polyester amides. The method according to any one of claims 1 to 4, wherein the amount of lubricant in one, one or more or all layers is in the range of 0.005 to 4% by weight, and the content of blocker particles is preferably 0.005 in the outer top layer. To 4% by weight of the film. The method according to any one of claims 1 to 5, wherein the content of lubricant in one, one or more or all layers is in the range of 0.05 to 1% by weight, and the content of blocker particles is preferably 0.05 in the outer top layer. To a film in the range of 1% by weight. The film according to claim 1, which is a three layer film with an additional inner layer (third layer) having a lower melting point compared to the inner layer directly adjacent to the outer layer. The film according to any one of claims 1 to 7, wherein the stretching ratio of the film uniaxially extended in the longitudinal direction and stretched uniaxially is 1: 1.5 to 1:10 in the longitudinal direction. The film of claim 8, wherein the stretching ratio of the uniaxially stretched film is from 1: 2.8 to 1: 8 in the longitudinal direction. 8. The biaxially stretched biaxially stretched biaxially stretched film according to any one of claims 1 to 7, wherein the total stretching ratio in the longitudinal direction is from 1: 1.5 to 1:10 and the transverse stretching ratio is 1: 2. To 1:20 film. The film according to claim 10, wherein the total stretching ratio in the longitudinal direction of the biaxially stretched film is 1: 2.8 to 1: 8, and the total stretching ratio in the lateral direction is 1: 3.8 to 1:15. The film according to claim 10 or 11, wherein the biaxial stretching is carried out by a sequential process with the onset of longitudinal stretching. The film according to claim 1, wherein the film has a thickness of less than 500 μm. The film according to claim 1, wherein the film has a thickness of less than 80 μm. The film according to claim 1, wherein the outer layer has a thickness of 5 to 20 μm and the thickness of the inner layer directly adjacent thereto is 20 to 40 μm. The film of claim 1, wherein all of the polyester amides are biodegradable and corrosive. The film according to claim 1, wherein the film comprises an organic or inorganic pigment in at least one layer for coloring purposes. 18. The film of claim 17, wherein the pigment is biologically harmless and / or present in an amount of less than 1% by weight. For packaging in the field of food or non-food materials, for greenhouse cover or mulch film in the horticulture and agriculture sectors, for the storage and transport of materials when finishing bags, for the protection and separation of cosmetics and hygiene products Multilayer films in printed, unprinted or colored form as well as in pretreated or untreated forms for surface protection or surface refining in the field of dragons, cards, paper and character window linings, or pretreated or Use of the film according to any one of claims 1 to 18 as an unpretreated, printed or non-printed form as well as a refined film which can be provided with an adhesive and used as a label or adhesive strip. Use of a film according to any one of claims 1 to 18 in the production of coated films, composites or laminates from the same or different polyester amides or with other non-biodegradable types of films. 21. The use according to claim 20, wherein all films, coating materials and adhesives used in composites or laminates or in coated films are biodegradable and corrosive. The polyester amide is first fused by the action of heat and shear forces, and the resulting melt is released from the tool in the form of a tubular film or a flat film and cooled until it solidifies. A method of making two or more layers of films according to any one of the preceding claims. The temperature according to claim 22, wherein the tubular film after cooling is adjusted to a temperature above the glass transition temperature to below the crystal melting temperature in the case of partially crystalline polyester amide, and above the glass transition temperature in the case of amorphous polyester amide. And biaxially stretching one or more times after adjusting to, optionally fixing after stretching or individual stretching, and optionally surface treatment after such stretching and fixing. 23. The method of claim 22, wherein the flat film after cooling is adjusted to a temperature above the glass transition temperature to below the crystal melting temperature for partially crystalline polyester amides, and above the glass transition temperature for amorphous polyester amides. And uniaxially or biaxially at least one time after adjustment, and optionally fixing after stretching or individual stretching, and optionally surface treatment after such stretching and fixing.