WO2000036014A2

WO2000036014A2 - Biodegradable, thermoplastic shaped bodies exhibiting an improved stability with regard to hydrolysis and an improved resistance to stress cracking

Info

Publication number: WO2000036014A2
Application number: PCT/EP1999/009526
Authority: WO
Inventors: Michael Kleemiss; Annett Kaeding; Gunter Weber; Heiko Tamke
Original assignee: Wolff Walsrode Ag
Priority date: 1998-12-15
Filing date: 1999-12-06
Publication date: 2000-06-22
Also published as: EP1144507A2; BR9916117A; JP2002532603A; AU1970900A; WO2000036014A3; CA2354514A1; EP1144507A3

Abstract

The invention relates to biodegradable, thermoplastic shaped bodies, especially single-layer or multilayer films, which exhibit an improved stability with regard to hydrolysis, an improved stress cracking behavior, and an improved behavior with regard to biodegradation. The inventive thermoplastic shaped bodies consist of a blend comprised of at least two different biodegradable polymers.

Description

Biodegradable, thermoplastic moldings with improved hydrolysis stability and stress crack resistance

The invention relates to biodegradable, thermoplastic, extruded moldings, in particular single-layer or multilayer films with improved hydrolysis stability and stress crack resistance.

It is known that certain polymers, like other materials, can be subject to biological degradation. The main materials to be mentioned here are those that are obtained directly or after modification from naturally occurring polymers, for example polyhydroxyalkanolates such as polyhydroxybutyrate, plastic celluloses, cellulose ether esters, cellulose esters, plastic starches, chitosan and pullulan. A targeted variation of the polymer composition or the structures, as is desirable on the part of the polymer application, is such

Polymers are difficult and often only possible to a very limited extent due to the natural synthesis process. For the purposes of this invention, the terms "biodegradable and compostable polymers or molded articles" are understood to mean goods which are tested for "biodegradability" in accordance with the test according to DIN V 54 900 from 1998/1999.

However, many of the synthetic polymers are not attacked by microorganisms, or only very slowly. Mainly synthetic polymers that contain hetero atoms in the main chain are considered to be potentially biodegradable. An important class within these materials are the polyesters. Synthetic raw materials that only contain aliphatic monomers have a relatively good biodegradability, but can only be used to a very limited extent due to their material properties; see Witt et al. in Macrom. Chem. Phys., 195 (1994) pp. 793-802. Aromatic polyesters, on the other hand, show significantly deteriorated biodegradability with good material properties. From DE-A-44 32 161 and EP-A-641 817, various biodegradable, synthetic polymers based on polyester or polyester amide have become known. These have the property that they are easy to process thermoplastically and, on the other hand, are biodegradable, i.e. their entire polymer chain is broken down by microorganisms (bacteria and fungi) by means of enzymes and completely broken down into carbon dioxide, water and biomass, so that they can be broken down accordingly Test in a natural environment under the influence of microorganisms meet the conditions for biodegradability according to DIN V 54 900. Due to the thermoplastic behavior, these biodegradable materials can be processed into semi-finished products such as cast or blown films.

However, the use of these semi-finished products is very limited. For example, the resistance to hydrolysis and stress cracking is not sufficient for many applications, or the desired biodegradation occurs too quickly in certain applications.

The object of the present invention was therefore to provide moldings, in particular single-layer or multilayer films, made of biodegradable polymers with improved hydrolysis resistance and improved stress crack resistance. Hydrolysis is understood to mean the destruction of the shaped body by aqueous media, which may also have an acidic or alkaline pH.

Stress crack formation is understood to mean damage mechanisms that occur under the influence of the environment, physical and / or chemical, due to an interaction with the surrounding media in the presence of internal or external mechanical stresses or strains.

The term stress cracking (ESC = Euvironnetal Stress Cracking and Crazing) is described in the literature (EJ Kramer, Environmental Cracking of Polymers, in Developments in Polymer Fracture-1, Edited by EH Andrews, Science publishers LTD London, 55-120 (1979) . The goal is achieved in that the diffusion of the permeating surrounding aqueous medium into the microstructure of the shaped body takes place so slowly that failure of the shaped body due to chain breakage, if not prevented, is nevertheless delayed.

According to the invention, a multiphase morphology of the shaped bodies is provided for this purpose, which is preferably generated by a binary blend of two biodegradable polymers. According to the invention, a multi-phase morphology can also be generated by blends with more than just two biodegradable polymers as blend partners.

The damage mechanisms under the interaction with the non-existent medium are advantageously reduced in that a blend partner shows only a slight interaction with the medium.

A particularly advantageous multiphase morphology exists when the diffusion path of the surrounding medium through the shaped body becomes as large as possible, e.g. with a layer-like or lamellar structure of the glare partner in microscopic dimensions.

For this purpose, the blend partners must be selected so that there is a high degree of phase compatibility, but not necessarily molecular miscibility, of the blend partners. The occurrence of mixture gaps should be avoided. The phase compatibility can be increased both by similar melt viscosities of the blend partners and by extrusion conditions.

In addition, the preferred embodiment of the moldings according to the invention contains additives and auxiliary substances, as will be explained below. Shaped bodies which are particularly preferred according to the invention are single-layer or multilayer films which can be produced by coextrusion, coating, lamination according to the prior art.

In the case of a single-layer structure, the corresponding films consist overall of a blend according to the invention and, if appropriate, customary additives and auxiliaries, as are explained below. In the case of a multilayer structure of the film, at least one layer consists of a blend according to the invention, as described above, and, if appropriate, the usual additives and auxiliaries mentioned. In a particularly preferred embodiment, this layer is arranged as an outer layer on that side of the film which is in contact with the hydrolyzing medium during use. However, according to the invention, several or all layers of the multilayer film can also be constructed as described above for the single-layer film, the ratio of the blend partners and the additives and auxiliaries depending on the type and amount in each layer being different.

For the blend according to the invention, preferably at least one polymer from each of the two subsequent groups labeled blend partner (I) and blend partner (II) is used.

Suitable blend partners (I) for thermoplastic molded articles according to the invention, in particular single-layer or multilayer films with improved resistance to hydrolysis and stress cracking are:

Biodegradable aliphatic or partially aromatic polyesters, in which the aromatic acids make up a proportion of not more than 60% by weight, based on all acids, preferably formed from

a) aliphatic bifunctional alcohols, preferably linear C ₂ to C ₁₀ dialcohols such as, in particular, ethanediol, hexanediol or very particularly preferably adds butanediol and / or cycloaliphatic bifunctional alcohols, preferably with 5 or 6 carbon atoms in the cycloaliphatic ring, such as in particular cyclohexanedimethanol, and / or partially or completely instead of the diols monomeric or oligomeric polyols based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers thereof with molecular weights up to 4000, preferably up to 1000, and optionally small amounts of branched bifunctional alcohols, preferably C ₃ -C ₁₂ -alkyldiols, in particular neopentyl glycol, and additionally optionally small amounts of higher-functional alcohols such as preferably 1,2,3-propanetriol or Trimethylolpropane as an alcohol-functionalized building block and from aliphatic bifunctional acids, preferably C ₂ -C ₁₂ -alkyldicarboxylic acids, particularly preferably succinic acid or adipic acid and optionally aromatic bifunctional acids such as preferably terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and additionally optionally small amounts of higher functional acids, preferably trimellitic acid as an acid-functionalized building block or

b) from acid- and alcohol-functionalized building blocks, preferably with 2 to 12 carbon atoms in the alkyl chain, preferably hydroxybutyric acid, hydroxyvaleric acid, lactic acid, or their derivatives, for example ε-caprolactone or dilactide,

or a mixture of several of the stated polyesters and / or one or more copolymers from the building blocks a) and b) with the exception of pure polylactide or poly-ε-caprolactone or copolymers formed exclusively from dilactide and ε-caprolactone.

Also suitable as blend partners (I) are biodegradable, aliphatic or partially aromatic polyester urethanes derived from the above biodegradable aliphatic or partially aromatic polyesters, which in addition to the above preferably contain ester groups formed from building blocks a) and / or b), which are preferably formed from

c) aliphatic and / or cycloaliphatic bifunctional and additionally optionally higher-functional isocyanates, preferably with 1 to 12 carbon atoms

Atoms or 5 to 8 carbon atoms in the case of cycloaliphatic isocyanates, preferably tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, optionally additionally with linear and / or branched and / or cycloaliphatic bifunctional and / or higher-functional alcohols, preferably C ₃ -C ₁₂ - Alkyl di- or polyols or cycloaliphatic alcohols with 5 to 8 carbon atoms, preferably ethanediol, hexanediol, butanediol, cyclohexanedimethanol, and / or optionally additionally with linear and / or branched and / or cycloaliphatic bifunctional and / or higher functional amines and / or amino alcohols with preferably 2 to 12 carbon atoms in the alkyl chain, preferably ethylenediamine or aminoethanol, and / or optionally further modified amines or alcohols, in particular ethylenediaminoethanesulfonic acid, as the free acid or as a salt,

wherein the ester portion preferably formed from a) and / or b) is at least 75

% By weight, based on the total weight.

Also suitable as blend partners (I) are aliphatic or partially aromatic polyester carbonates derived from the above aliphatic or partially aromatic polyesters, which in addition to building blocks a) and / or b) contain carbonate groups, which are preferably formed from:

d) a carbonate fraction which is prepared from aromatic bifunctional phenols, preferably bisphenol-A, and carbonate donors, in particular phosgene, or a carbonate fraction which is derived from aliphatic carbonic acid esters or their derivatives, such as preferably chlorocarbonic acid esters or aliphatic table carboxylic acids or their derivatives such as salts and carbonate donors, in particular phosgene, is produced, wherein

the ester fraction preferably formed from a) and / or b) is at least 70% by weight, based on the total weight.

Particularly suitable as blend partners (I) are aliphatic or partially aromatic polyester amides derived from the above aliphatic or partially aromatic polyesters, which in addition to the building blocks a) and / or b) contain amide groups, which were preferably formed from

e) aliphatic and / or cycloaliphatic bifunctional amines, preferably linear aliphatic C ₂ to C ₁₀ diamines, in particular isophoronediamine and very particularly preferably hexamethylenediamine, where these amines may contain small amounts of branched bifunctional amines and / or higher-functional amines and also from linear and / or cycloaliphatic bifunctional acids, preferably with 2 to 12 C atoms in the alkyl chain or C ₅ or C ₆ ring in the case of cycloaliphatic acids, preferably adipic acid, and optionally small amounts of branched bifunctional and / or optionally aromatic bifunctional acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and additionally optionally small amounts of higher functional acids, preferably with 2 to 10 carbon atoms, or

f) acid- and amine-functionalized building blocks, preferably with 4 to 20 C-

Atoms in the cycloaliphatic chain, preferably co-laurolactam, particularly preferably ε-caprolactam,

or a mixture of e) and f), the ester fraction preferably formed from a) and / or b) being at least 20% by weight, based on the total weight, preferably the ester content is 20 to 80% by weight, and the content of the amide structures is 80 to 20% by weight.

The blend partners (I) used in thermoplastic molded articles according to the invention, in particular single-layer or multilayer films, can be both pure polymers and mixtures of various of the polymers mentioned, in the case of mixtures preferably polymers of only one of the aforementioned classes of compounds ( Polyesters, polyester urethanes, polyester carbonates, polyester amides) can be used. Polyester amides or mixtures of different polyester amides are particularly preferably used.

Suitable blend partners (II) for moldings according to the invention, in particular single-layer or multilayer films with improved hydrolysis stability and stress crack resistance, are suitable aliphatic polyesters made from linear bifunctional alcohols, such as preferably ethylene glycol, hxanediol or particularly preferably butanediol and / or cycloaliphatic bifunctional alcohols, such as preferably cyclohexane dimethanol and additionally optionally small amounts of higher-functional alcohols, such as preferably 1,2,3-propanetriol or neopenthyl glycol and from linear bifunctional acids, such as preferably succinic acid or adipic acid and / or optionally cycloaliphatic bifunctional acids, such as preferably

Cyclohexanedicarboxylic acid or from acid- and alcohol-functionalized building blocks, preferably hydroxybutyric acid or hydroxyvaleric acid or their derivatives, for example ε-caprolactone and mixtures thereof. Preferred blend partners (II) are aliphatic polyesters, polycaprolactone and polylactides formed from these monomers, in particular polylactic acid, polyhydroxybutyric acid, polyhydroxybenzoic acid, polyhydroxybutyric acid / hydroxivaleric acid copolymers and mixtures of these polymers and copolymers from the monomers forming these mixtures. Poly-ε-caprolactone is very particularly suitable. According to the invention, the polymers used as blend partners (I) and blend partners (II) must not be composed of identical monomers.

In order to achieve improved hydrolysis stability and stress crack resistance, it is necessary that the blend according to the invention is subjected to an orienting stress in the production of the extruded molded articles according to the invention, as it inevitably occurs in the extrusion process if the blend is mixed in the desired composition by mixing and / or metering systems is plasticized and melted in the extrusion system and emerges from the nozzle. In the preferred embodiment of the thermoplastic molded body as a single-layer or multilayer film, targeted stretching of the molded body after the melt extrusion allows further improvements in the hydrolysis stability and the stress crack resistance to be achieved, which are due to the choice of the nozzle gap width, the rate of melt withdrawal and in the case of

Blown film production of the inflation ratio can be influenced.

The composition of the blend according to the invention can be varied over a wide range. For example, the proportion of the blend partner (I) can be between 1 and 99% by weight and that of the blend partner (II) can be between 99 and 1% by weight based on the total of the blend partners, and the desired properties can be set by the proportion of the blend partners of the molded body such as hydrolysis stability, stress crack resistance and the rate of damage caused by biological and / or physical / chemical degradation.

However, a low proportion of blend partner (II) only leads to a slight improvement in the resistance to hydrolysis and stress cracking, while a high proportion of blend partner (II) increases the tendency to block, particularly when extruding foils, so that either the processing speed is reduced or generally undesirably high proportion of lubricant must be added. The proportion of the blend partner (I) is therefore preferably from 10 to 90% by weight and that of the blend partner (II) from 90 to 10% by weight. A proportion of the blend partner (I) of 40 to 60% by weight and correspondingly of the blend partner (II) of 60 to 40% by weight, in each case based on the sum of the blend partners, is particularly preferred.

The blends used for thermoplastic molded articles according to the invention, in particular single-layer or multilayer films, can additionally contain customary additives and auxiliaries. The following additives and auxiliaries are preferably used:

From 0 to a maximum of 5% by weight of nucleating agents typically used for polyester (for example 1,5-naphthalene disodium sulfonate or layered silicates, for example talc, or nucleating agents of nanoparticle size, ie average particle diameter <1 μm, for example of titanium nitride, aluminum hydroxyl hydrate, barium sulfate or zirconium compounds) and / or 0 to a maximum of 5% by weight of the customary stabilizers and neutralizing agents and / or 0 to a maximum of 5% by weight of the usual lubricants and release agents and / or 0 to a maximum of 5% by weight of the customary antiblocking agents and optionally pigments Coloring.

The usual stabilizing compounds for polyester compounds can be used as stabilizers and neutralizing agents. The amount added is 0 to a maximum of 5% by weight.

Phenolic stabilizers, alkali / earth alkali stearates and / or alkali earth alkali carbonates are particularly suitable as stabilizers. Phenolic stabilizers are preferred in an amount of 0 to 3% by weight, in particular 0.15 to 0.3% by weight and with a molar mass of more than 500 g / mol. Pentaerythrityl tetrakis-3 (3,5-di-tertiary-butyl-4-hydroxyphenyl) propionate or 1,3,5-trimethyl-2,4,6-tris (3,5-di-tertiary-butyl-4 Hydroxybenzyl) benzene are particularly advantageous. Neutralizing agents are preferably dihydrotalcite, calcium stearate, calcium carbonate and / or calcium montanate with an average particle size of at most 0.7 μm, an absolute particle size of less than 10 μm and a specific surface area of at least 40 m ² / g.

In a particularly preferred embodiment of the film, it has a nucleating agent content of 0.00001 to 2% by weight and a stabilizer and neutralizing agent content of 0.00001 to 2% by weight.

Lubricants and release agents are higher aliphatic amides, tertiary amines, aliphatic

Acid amides, higher aliphatic acid esters, low-molecular polar-modified waxes, montan waxes, cyclic waxes, phthalates, metal soaps and silicone oils. The addition of higher aliphatic acid amides and silicone oils is particularly suitable.

Among the aliphatic amides, the supply forms from ethylene amide to stearyl amide are particularly suitable. Aliphatic acid amides are amides of a water-insoluble monocarboxylic acid (so-called fatty acids) with 8 to 24 carbon atoms, preferably 10 to 18 carbon atoms. Erucic acid amide, stearic acid amide and oleic acid amide are preferred among them.

Also suitable as release agents or lubricants are compounds which contain both esterais and amide groups, such as stearamide ethyl stearate or 2 stear amido ethyl stearate.

A number of different compounds fall under the name Montan waxes. See Neumüller et al. in Römpps Chemie-Lexikon, Franckh'sche Verlagshandlung, Stuttgart, 1974.

Examples of cyclic waxes are components such as cyclic adipic acid tetramethylene esters or 1.6-dioxa-2.7-dioxocyclododecane, or the homologous hexa- suitable methylene derivative. Such substances are known as commercial products with the name Glycolube VL.

Suitable silicone oils are polydialkylsiloxanes, preferably polydimethylsiloxane, polymethylphenylsiloxane, olefin-modified silicone, silicone modified with polyethers such as, for. B. polyethylene glycol and polypropylene glycol and epoxyamino- and alcohol-modified silicone. The viscosity of the suitable silicone oils is in the range from 5,000 to 1,000,000 mm ^/ s. Polydimenthylsiloxane with a viscosity of 10,000 to 100,000 mm ² s is preferred.

The amount of lubricant added is 0 to a maximum of 5% by weight. In a particularly preferred embodiment of the single-layer or multilayer film according to the invention, it has a lubricant content of 0.005 to 4% by weight. In a very particularly preferred embodiment of the film, it has a lubricant content of 0.05 to 1% by weight. In the case of a multilayer film, one, more or all layers can contain lubricants.

Suitable antiblocking agents are both inorganic and organic additives which, because of their particle size and / or shape, protrude from the surface of the film and thus cause a spacer effect.

In a preferred form, the following substances are used as inorganic antiblocking agents:

Aluminum hydroxide

Aluminum silicates, for example kaolin or kaolin clay,

Aluminum oxides, for example Θ aluminum oxide

Aluminum sulfate

Ceramics made of silica-aluminum oxides, barium sulfate, natural and synthetic silicas Layered silicates, for example asbestos,

Silicon dioxide

Calcium carbonate of the calcite type

Calcium phosphate magnesium silicates

Magnesium carbonate

Magnesium oxide

Titanium dioxide

Zinc oxide micro glass balls and the following substances are used as organic antiblocking agents: organic polymers incompatible with the biodegradable polymer such as

Strength

Polystyrene cross-linked and uncross-linked polymethyl methacrylate cross-linked polysiloxane (e.g. Tospearl) polar-modified polyethylene (e.g. maleic anhydride-grafted polyethylene) polar-modified polypropylene (e.g. maleic anhydride-grafted polypropylene) statistical copolymer based on ethylene or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid or acrylic or methacrylic acid - Reester or metal salts of methacrylic acid or metal salts of methacrylic acid esters

Benzoguanamine formaldehyde polymers.

The effective amount of antiblocking agent is in the range from 0 to a maximum of 5% by weight.

%. In a particularly preferred embodiment, the film contains 0.005 to 4% by weight

Antiblocking agents. In a very particularly preferred embodiment, the film contains

0.05 to 1 wt .-% antiblocking agent. The average particle size is between 1 and 20 μm, in particular 2-12 μm, particles with a spherical or ellipsoidal shape, as described in EP-A-0 236 945 and DE-A-38 01 535, are particularly suitable. Combinations of different spacer systems are also particularly suitable. In a particularly preferred embodiment, the spacer systems are added to the outer cover layers in multilayer films.

The moldings according to the invention, in particular in the form of single or multilayer films, can have 0 to max. Contain 10% by weight pigments for coloring. These can be organic or inorganic pigments. In a particularly preferred form, the pigments are biologically harmless and / or have a concentration of less than 1% by weight.

To produce the film according to the invention, the polymers for the film, optionally provided with additives, are provided with the desired amounts by weight of organic or inorganic additives and / or auxiliaries in the production of raw materials in accordance with the customary prior art. This happens at

Granulation of the raw material, for example in twin-screw extruders, where the additives are added to the raw material. In addition to this type of additive, there is also the possibility that some or all of the necessary additives are added to a raw material that is not or only partially finished in the form of a masterbatch. The term masterbatch in the context of the present invention is a

To understand masterbatch, in particular a granular, dust-free concentrate of a plastic raw material with high amounts of additives, which is used in the mass preparation as an intermediate product (as a material additive to a granulate that is not or only partially or incompletely equipped with additives) in order to produce films therefrom, that contain a certain amount of additives. The

Masterbatch is mixed into the extruder in such amounts before the polymer granules are added to the polymer raw materials which are not or only partially or incompletely equipped with additives, so that the desired percentages by weight of additives and / or auxiliaries are achieved. The preferred materials from which the masterbatches are produced in addition to the additives and / or auxiliaries are substances which are compatible with the polymers mentioned in this invention.

The moldings according to the invention, in particular in the embodiment as a single-layer or multilayer film, are produced using a conventional extrusion process. The polymers in granular form, optionally including the desired additives and auxiliaries, are melted in one or more extruders, homogenized, compressed and discharged via a single- or multi-layer nozzle. In the case of the preferred embodiment, the single-layer or multi-layer film can be an annular nozzle for producing a seamless tubular film or a flat nozzle for producing a flat film. The carried out or e.g. foil pulled out by roller pressers is then cooled until solidification. The cooling can take place both over air and over water or also by means of cooling rollers. The

Cooling can take place on one or both sides, in the case of a tubular film on the inside and outside or only on the inside or only on the outside. The orientation and thus the hydrolysis stability and the stress crack resistance can be influenced by the choice of the nozzle gap size, the withdrawal speed and, in the case of a tubular film, the inflation ratio. The tubular film can also be cut on one or both sides, so that a multilayer flat film is obtained.

After cooling, the film can be tempered below the crystalline melting temperature in the case of partially crystalline materials and above the glass transition temperature in the case of amorphous materials, and then stretched one or more times monoaxially or biaxially, the biaxial stretching being able to take place successively or, in particular in the case of tubular films, simultaneously. After the stretching stage or stages, the film can optionally be fixed by heat treatment. A particularly suitable stretching method is for simultaneous biaxial

Stretching tubular films using the so-called double bubble technology, in which the A primary bladder is stretched over an applied internal pressure. The film can then be subjected to a heat treatment in order to adjust the shrinkage properties. In this fixing process, the film can be heated up to just below the crystalline melting temperature.

If a corona treatment is subsequently to be carried out, the procedure is expediently such that the film is passed through between two conductor elements serving as electrodes, such a high voltage, usually alternating voltage (approximately 5 to 20 kV and 5 to 30 kHz) being applied between the electrodes that spray or corona discharges can take place. The air above the film surface is ionized by the spray or corona discharge and reacts with the molecules of the film surface, so that additional polar deposits occur in the polymer matrix.

For a flame treatment with a polarized flame (see US Pat. No. 4,622,237) which may follow the stretching or fixing process, an electrical direct voltage is applied between a burner (negative pole) and a cooling roller. The applied voltage is between 400 and 3,000 V, preferably in the range of 500 to 2,000 V. The applied voltage gives the ionized atoms increased acceleration and hits the polymer surface with greater kinetic energy. The chemical bonds within the polymer molecule are broken more easily and the radical formation takes place more quickly. The thermal load on the polymer is much lower than in the standard flame treatment, and films can be obtained in which the sealing properties of the treated side are even better than those of the untreated side.

In a possibly subsequent to the stretching or fixing process plasma pretreatment, gases, e.g. B. oxygen or nitrogen or carbon dioxide or methane or halogenated hydrocarbons or

Silane compounds or higher molecular compounds or mixtures thereof from, a high energy field, e.g. B. exposed to microwave radiation. High-energy electrons are created, which hit the molecules and transfer their energies. This creates local radical structures, the excitation states of which correspond to temperatures of a few tens of thousands of degrees Celsius, even though the plasma itself is almost at room temperature. This makes it possible to break chemical bonds and initiate reactions that can normally only take place at high temperatures. Monomer radicals and ions are formed. The resulting monomer radicals form - partly in plasma - short-chain oligomers, which then condense and polymerize on the surface to be coated. A homogeneous film is deposited on the coating material.

However, before the monomer radicals or ions deposit on the substrate, there is also the option of adding a further material flow to the excited molecules in the so-called after-glow zone. This makes it possible to produce a substance or a mixture of substances which, when it strikes the polymer film surface, produces an oxidative attack on the substrate polymers. A glassy and mostly highly cross-linked layer is formed, which is firmly attached to the film surface. With a suitable material composition, this results in an increase in the surface tension on the film.

In the preferred embodiment as a single-layer or multilayer film, the shaped body according to the invention has a thickness of preferably less than 1000 μm, in particular less than 500 μm and very particularly preferably less than 80 μm.

The invention also relates to the use of the thermoplastic molded articles according to the invention in the preferred embodiment as a single-layer or multilayer film. The preferred application is the use of this film, in particular as a multilayer film in pretreated or untreated as well as in printed or unprinted form for the packaging in the areas

Food and non-food or as hydrolysis-stabilized, one or multilayer film in pretreated or untreated form for protective and separating functions in connection with cosmetics and hygiene articles, for example for baby diapers or sanitary napkins or as hydrolysis-stabilized, single or multilayer film in pretreated or untreated form for surface protection or surface finishing in the area of cardboard -, paper and letter window lamination or as a finished film, which can be used in pretreated or untreated as well as printed or unprinted form and provided with adhesive as a label or adhesive strip.

Furthermore, the hydrolysis-stabilized, single-layer or multilayer film can be refined in pretreated or untreated form for greenhouse covers, mulch films or for lining plant-growing boxes (for example for mushroom cultivation) in the horticultural or agricultural sectors or for sacks for the storage and transport of goods For example, organic waste is used, whereby the proportion of the blend partners, the multilayer structure and the orientation of the molecules / crystals can be used to control the hydrolytic and biotic degradation rate.

The invention furthermore relates to the use of a multilayer film according to the invention as a starting material for the production of a bag which releases its contents after the disintegration by the biological degradation process. The bag can be produced by gluing and sealing the film and can both be closed and have an opening with a corresponding closure or connection.

In a particularly preferred form, only those substances are used for the applications mentioned that the overall composite is also biodegradable and compostable in accordance with DIN V 54 900.

The invention furthermore relates to the use of the multilayer film according to the invention as a starting material for the production of a packaging or release or surface protection film with very high water vapor permeability by piercing this film with a cold or tempered needle roller. The purpose of this film is the packaging of moisture-releasing goods, for example bread or various types of fruit or vegetables, or as a separating and protective film in the hygiene area.

Examples

Example 1 (comparative example)

Made from a biodegradable and compostable polymer (polyester amide

54% ε-caprolactam, 23% adipic acid and 23% 1,4-butanediol, LP BAK 403-004, Bayer AG), a film with a thickness of 40 μm and a width of 330 mm was produced on a single-layer blown film line . The material had an MFI of 7 (in g / 10 min at 190 ° C, 2.16 kg, measured according to DIN 53 735), a melting point of 125 ° C, measured according to ISO 3146 7 C2, a proportion of lubricant of

0.3% by weight and an antiblock content or nucleating agent content of 0.2% by weight. The maximum extrusion temperature was 165 ° C, the melt temperature 190 ° C. the melt was discharged through an annular die and cooled by air. The maximum nozzle temperature was 155 ° C.

Example 2

From a mixture of the polymer from Example 1 as blend partner (I) and a blend partner (II) (poly-ε-caprolactone clays P 787, Union Carbide), the proportion of blend partner (II) being 20% by weight the same system from Example 1, a single-layer blown film. The blend partner (IΙ) had an MFI of 2.8 (in g / 10 min at 190 ° C, 2.16 kg, measured according to DIN 53 735) and a melting point of 60 ° C, measured according to ISO 3146 / C2. The maximum extrusion temperature was 160 ° C, the maximum nozzle temperature was 155 ° C. A flat film tube with a total thickness of 80 μm could be produced using the same method as in Example 1. Example 3

A single-layer blown film was produced on the same system from Example 1 from the same materials from Example 2, but here the proportion of the blend partner (II) was 40% by weight. The maximum extrusion temperature was

160 ° C, the maximum nozzle temperature was 150 ° C. A flat film tube with a total thickness of 80 μm could be produced using the same method as in Example 1.

Example 4

A single-layer blown film was produced from the same materials from Example 2, but the proportion of the blend partner (II) here was 60% by weight, using the same system from Example 1. The maximum extrusion temperature was 155 ° C, the maximum die temperature was 135 ° C. It could do the same

Process as in Example 1, a flat film tube with a total thickness of 80 microns are produced.

The mechanical quantities of tensile strength and elongation at break in the longitudinal and transverse directions were determined in accordance with DIN 53 455 on the samples produced. The E module in the longitudinal and transverse directions was determined in accordance with DIN 53 457. The thickness of the individual samples was determined in accordance with DIN 53 370. In the tear test, the tear strength was measured as the maximum force and the tear resistance (tear strength based on sample thickness) in the longitudinal and transverse directions. The samples were then stored in water for 24 hours. By decreasing the

Tear strength, elongation at break and tear resistance depending on the storage time, the hydrolytic degradation and the stress crack resistance can be influenced by the choice of the nozzle gap size, the withdrawal speed and in the case of a tubular film the inflation ratio, the orientation and thus the hydrolysis stability and the stress crack resistance can be influenced. The results of the tests on the samples from Examples 1, 2, 3 and 4 are listed in Table 1 and shown graphically in Fig. 1.

Transmission electron microscope examinations of contrasted ultra-thin sections of the film show the multi-phase structure (Figures 2 to 7).

The formulas OSO ₄ treatment show the PA-rich phase of the blind partner I in high contrast (see Fig. 2). Accordingly, the blend partner II forms its own crystalline phase, which has a good phase compatibility with the blend partner I. With an operating ratio of blend partner I to blend partner II of 40/60, both mixture components form a continuous phase, which in

Form of layers with lateral dimensions of about 0.2 to 0.4 microns exists.

Bags were welded from the film sample using a separating seam welder. Five bags were made from each film sample. The bags were filled with fresh organic household waste and stored dry at an ambient temperature of approx. 15 ° C. The bags were examined for damage caused by degradation at intervals of one day.

The results of the tests on the samples from Examples 1, 2, 3 and 4 are shown in Table 2.

Table 1:

Results of the tensile and tear tests depending on the storage time in water

Table 2: Bio waste bags - storage test with deposited compost

5 bags each were filled with deposited compost and stored in the boiler room. They were regularly checked for damage.

Pattern glare partner (I) glare partner (II) thickness [μm]

1 100% B AK 403-004 40 acc. Example 1

2 80% BAK 403-004 20% polycaprolactone 40 acc. Example 2

3 60% BAK 403-004 40% polycaprolactone 40 acc. Example 4

4 40% BAK 403-004 60% polycaprolactone 40 acc. Example 4

5 20% BAK 403-004 80% polycaprolactone 40

6 100% polycaprolactone 40

7 80% BAK 403-004 11% TIR 3700 A 40

Storage conditions: dark, approx. 25 ° C.

The shelf life in relation to deposited compost is shown graphically in FIG. 1.

Finding

Samples 1, 2 and 7 have insufficient compost resistance with the damage pattern of cracks in the area of folds. In the 2nd week, the damage pattern mainly shows seam cracks, from the 3rd week small round holes appear in the area of the filling material, which after a few days grow into irregular areas due to bacterial degradation. The compost resistance is significantly improved from a 40% share of blend partner (II), the mixture of 60% blend partner (II) and 40% blend partner (I) was the most stable in this experiment.

Claims

claims

1. Biodegradable, thermoplastic molded articles containing a blend of at least two different, biodegradable polymers as blend partners (I) and blend partners (II), which are selected such that phase compatibility, but no molecular miscibility, between blend partners (I) and (II) consists.

2. molded article according to claim 1, characterized in that the molded article contains a binary blend of two different, biodegradable polymers.

3. molded article according to one of claims 1 or 2, characterized in that the proportion of the blend partner (I) in the blend 1 to 99 wt .-%, preferably 10 to 90 wt .-% and in particular 40 to 60 wt .-% and the

The proportion of the blend partner (II) is correspondingly 99 to 1% by weight, preferably 10 to 90% by weight and in particular 60 to 40% by weight, in each case based on the sum of the blend partners.

4. molded article according to any one of claims 1 to 3, wherein as a blend partner (I) biodegradable aliphatic polyester or partially aromatic polyester with a proportion of aromatic acids of not more than 50 wt .-%, based on all acids or functional derived from these polyesters Derivatives in the form of polyester urethanes with an ester content of at least 75% by weight, or polyester carbonates with an ester content of at least 70% by weight or polyester amides with an ester content of at least 20% by weight, or mixtures thereof, with the exception of pure polylactide or poly -ε-caprolactone or copolymers formed exclusively from dilactide and ε- caprolactone and biodegradable as blend partner (II), different from blend partner (I), or aliphatic polyesters or mixtures thereof. Shaped body according to one of claims 1 to 4, characterized in that the blend partner (I) is polyester

a) aliphatic bifunctional alcohols, preferably linear C ₂ to

C ₁₀ -dial alcohols, in particular ethanediol, hexanediol or very particularly preferably butanediol and / or cycloaliphatic bifunctional alcohols, preferably having 5 or 6 carbon atoms in the cycloaliphatic ring, such as in particular cyclohexanedimethanol, and / or partially or completely instead of the diols on monomeric or oligomeric polyols

Based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers thereof with molecular weights up to 4000, preferably up to 1000, and optionally small amounts of branched bifunctional alcohols, preferably C ₃ -C ₁₂ -alkyldiols, in particular neopentyglycol, and additionally optionally small amounts of higher-functional alcohols such as preferably 1 , 2,3-propanetriol or trimethylolpropane as an alcohol-functionalized building block and from aliphatic bifunctional acids, preferably C ₂ -C ₁₂ -alkyldicarboxylic acids, particularly preferably succinic acid or adipic acid and optionally aromatic bifunctional acids such as preferably

Terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and, if appropriate, small amounts of higher-functional acids such as trimellitic acid as acid-functionalized building block or

b) from acid- and alcohol-functionalized building blocks, preferably with 2 to 12 carbon atoms in the alkyl chain, preferably hydroxybutyric acid, hydroxyvaleric acid, lactic acid, or their derivatives, for example ε-caprolactone or dilactide, or a mixture of several of the polyesters mentioned and / or one or more copolymers from the building blocks a) and b) have been used.

6. Molded body according to one of claims 1 to 4, characterized in that aliphatic or partially aromatic polyester urethanes with urethane group are formed as blend partners (I)

c) aliphatic and / or cycloaliphatic bifunctional and additionally optionally higher-functional isocyanates, with preferably

1 to 12 carbon atoms or 5 to 8 carbon atoms in the case of cycloaliphatic isocyanates, preferably tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, optionally additionally with linear and / or branched and / or cycloaliphatic bifunctional and / or higher-functional alcohols, preferably

C ₃ -C ₁₂ alkyl di- or polyols or cycloaliphatic alcohols having 5 to 8 carbon atoms, preferably ethanediol, hexanediol, butanediol, cyclohexanedimethanol, and / or optionally additionally with linear and / or branched and / or cycloaliphatic bifunctional and / or Highly functional amines and or amino alcohols with preferably 2 to 12 carbon atoms in the alkyl chain, preferably ethylenediamine or aminoethanol, and / or optionally further modified amines or alcohols such as, in particular, ethylenediaminoethanesulfonic acid, can be used as the free acid or as a salt.

7. Molded body according to one of claims 1 to 4, characterized in that aliphatic or aliphatic-aromatic polyester carbonates are used as the blend partner (I) d) a carbonate fraction which is produced from aromatic bifunctional phenols, preferably bisphenol-A, and carbonate donors, in particular phosgene, or a carbonate fraction which is obtained from aliphatic carbonic acid esters or their derivatives, such as, for example, chlorocarbonic acid esters or aliphatic carboxylic acids or their derivatives such as salts and carbonate donors, for example phosgene, is used.

Shaped body according to one of claims 1 to 4, characterized in that aliphatic or partially aromatic polyester amides with amide groups are formed as the blend partner (I)

e) aliphatic and / or cycloaliphatic bifunctional amines, preferably linear aliphatic C ₂ to C ₁₀ diamines, in particular isophoronediamine and very particularly preferably hexamethylenediamine, where these amines can optionally contain small amounts of branched bifunctional amines and / or higher-functional amines, and from linear and / or cycloaliphatic bifunctional acids, preferably with 2 to 12 C atoms in the alkyl chain or C ₅ - or C ₆ ring in the case of cycloaliphatic acids, preferably adipic acid, and 5 to 8 C atoms, if appropriate, small amounts of branched bifunctional and / or optionally aromatic bifunctional acids such as terephthalic acid,

Isophthalic acid, naphthalenedicarboxylic acid and additionally, if appropriate, small amounts of higher-functional acids, preferably with 2 to 10 carbon atoms, or f) acid- and amine-functionalized building blocks, preferably with 4 to

20 carbon atoms in the cycloaliphatic chain, preferably ω-laurolactam, particularly preferably ε-caprolactam,

or a mixture of e) and f).

9. molded article according to any one of claims 1 to 8, characterized in that as the blend partner (II) aliphatic polyester from linear bifunctional alcohols, such as preferably ethylene glycol, hexanediol or particularly preferably butanediol and / or cycloaliphatic bifunctional alcohols, such as preferably cyclohexanedimethanol and additionally optionally small Amounts of higher-functional alcohols, such as preferably 1,2,3-propanetriol or neopenthyl glycol and from linear bifunctional acids, such as preferably succinic acid or adipic acid and / or optionally cycloaliphatic bifunctional acids, such as preferably cyclohexanedicarboxylic acid or from acid- and alcohol-functionalized building blocks, preferably Hydroxybutyric acid or hydroxyvaleric acid or their derivatives, where polycaprolactone, polylactides, in particular polylactic acid, polyhydroxybutyric acid, polyhydroxybenzoic acid, polyhydroxybutyric acid / hydroxyvaleric acid copolymers and M mixtures of these polymers and copolymers from the monomers forming these mixtures are particularly preferred.

10. molded article according to one of claims 1 to 8, characterized in that the blend partner II made of poly-ε-caprolactone with a molecular weight of greater than 10,000 gr / mol, preferably a molecular weight of

40,000 gr / mol to 80,000 gr / mol.

11. Molded body according to one of claims 1 to 10, characterized in that it is an injection molded part, an injection molded blow molded body or an extruded part in the form of plates, flat films or blown films or finished with chamfers, fleeces or from Wovens or combinations of these shapes.

12. Molded body according to one of claims 1 to 11, characterized in that it is a single-layer or multilayer film in which at least one layer consists of a blend of the blend partners (I) and (II) and, if appropriate, customary additives and auxiliaries .

13. Molded body in the form of a single-layer or multilayer film according to claim 12, characterized in that the film thickness is less than 1000 μm, preferably less than 500 μm and in particular less than 80 μm.

14. Use of a molded body in the form of a single or multilayer film for packaging in the areas of food or non-food or for greenhouse covers, mulch films or for lining

Plant growing boxes or sacks refined for the storage and transport of goods, or for protective and separating functions in connection with cosmetics and hygiene articles or for surface protection or surface finishing in the area of cardboard and paper lamination or as a label or adhesive strip.

15. A bag made of a single or multi-layer film according to one of claims 11 or 12, which releases its contents after decay by biodegradation.