JP2001509525A - Starch-based thermoplastic mixture for producing biodegradable molded articles - Google Patents

Abstract

  (57) [Summary] A) 100 parts by weight (calculated after correcting the water content to zero%) of the desired native, chemically modified starch, fermentable and / or recombinant starch and / or starch prepared by bioconversion. / Or derivatives of said starch; B) up to 100 parts by weight, if necessary, of a physiologically harmless, biodegradable, thermoplastically processable polymeric substance other than A); C) 1-100 parts by weight of water; D) 10 parts by weight to half of the sum of parts by weight of A) and B) of at least one plasticizer; E) at least one phosphate in an amount ranging from 0.01 parts by weight to (A) + (B) / 10 parts by weight; F) If necessary, up to ((A) + (B)) parts by weight of other conventional additives; A thermoplastic mixture based on starch for producing a biodegradable molded article having excellent properties, preferably excellent mechanical properties, which can be obtained by preparing and mixing A thermoplastic mixture in which the mixing of components E) and A) is carried out with the introduction of heat and mechanical energy into the thermoplastic mixture and, preferably, with the action of high temperatures and simultaneous shearing forces acting on the mixture .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] A starch-based thermoplastic mixture for the preparation of a biodegradable molded article having excellent properties, preferably excellent mechanical properties, and the preparation and use of said mixture.

The present invention relates to starch-based thermoplastic mixtures, the preparation of such mixtures and, moreover, the production of biodegradable shaped articles, such as shaped articles or films, which preferably have excellent mechanical properties. It also relates to the use of these mixtures to perform

[0003] Starch is a biocompatible substance, which itself has the excellent advantage of essentially good biodegradability. As a result of the widespread use of so-called hydrophilic polymers as natural and more physiologically compatible and degradable plastics for a very wide variety of applications, starch is produced by known plastic processing methods such as injection molding or extrusion. Considerable effort has also been put into processing. However, like molded articles or films, the products produced in this way have unsuitable mechanical properties,
For example, they often have inadequate strength or poor dimensional stability.

[0004] Limited improvements can be made by chemically modifying starch. There are many different reactions used to modify starch. Among these are oxidation treatments, polymer-like reactions with organic chemicals, cross-linking reactions, and graft polymerization in which starch is used as an initiator and monomers are bonded to the main chain.

In the further processing of starch mixtures using conventional polymer processing techniques, it is often of interest to melt the polymer mixture (eg in injection molding, blow molding, extrusion and coextrusion).

[0006] This requires that the molding composition made from starch has a thermoplastic behavior.

If the thermoplastic behavior of starch is to be improved by crosslinking, bifunctional molecules derived from aldehydes such as glyoxal, glutardialdehyde or dialdehyde starch, otherwise diisocyanates, An important role is often played by bifunctional molecules derived from epoxides, epichlorohydrin, diesters, etc., and if the amount of cross-linking agent is too large, the degree of cross-linking reaction will be less than that of starch. It may interfere with achieving the desired effect, which is the desired plasticity. In particular, relatively strong crosslinks lead to swellable but insoluble products.

The following publications are cited for more detailed prior art. WO90 / 05161 (PCT / CH89 / 00185) = D1, DE-A39 31 363 = D2, US2,801,242 = D3, US2,938,901 = D4, US2,328,537 = D5, WO94 / 21236 = D6 , EP-A0 143 643 = D7, DE-A2 308 886 = D8, EP-A0 391 853 = D9, EP-A0 298 920 = D10 and author Solarek, D.A. B. , Editor Otto B, publisher Boca Rato
n, Florida's "Modified Starches: Property"
is and Uses ", 1986, pp. 97-112 = D11. D1 is a process for thermoplastic processing by mixing additives with substantially native or native starch and applying heat and mechanical energy to melt the mixture. A possible starch preparation is described, in which the additive is a substance which lowers the melting point of starch, so that the melting point of the starch to which this additive is added is below the decomposition temperature of the starch. Is DMSO, 1,3-butanediol, glycerol, ethylene glycol, propylene glycol, butylene glycol, diglyceride, diglycol ether, formamide, N, N-dimethylformamide, N-
Methylformamide, N, N'-dimethylurea, dimethylacetamide and N
-Methylacetamide. D1 is di- or polycarboxylic acid and / or acid anhydride, di- or polycarboxylic acid halide and / or amide, dibasic or polybasic inorganic acid derivative, epoxides, formaldehyde, urea derivative,
It has also been proposed to add a crosslinking agent selected from the group consisting of divinyl sulfones, isocyanates, mono- or polyfunctional oxo compounds, and also cyanamide.

D2 relates to a method of reducing the swellability of starch by adding a crosslinkable reagent in pure or encapsulated form, followed by denaturation by effecting the crosslinking reaction by high temperature annealing. Crosslinking agents used are, in particular, urea derivatives, urotropins, trioxane, di- or polyepoxides, di- or polychlorohydrins, di- or polyisocyanates, carbonic acid derivatives, diesters or else inorganic esters such as phosphoric acid or boric acid. It is a polyacid. The mixture is treated with a very high weight ratio of crosslinking agent (10%) to achieve a suitable increase in mechanical stability by subsequent heat treatment.
~ 100% by weight).

D3 discloses a method for preparing distarch phosphates using sodium phosphates. Here, two types of starch chains are bonded to a phosphate molecule and crosslinked. However, in this case, the starch granules are retained and the starch does not plasticize.

[0011] D4 is a method similar to D3 for preparing a dust-free powder for application in the production field by suspending and dissolving starch granules that do not dissolve or swell with phosphoric acid and salts thereof. Disclose.

In D5, an inorganic chloride is used to modify starch granules in an aqueous suspension. This starch mixture is also not thermoplasticized before or during treatment with these chemicals.

D6 describes the use of crosslinkers, in particular epichlorohydrin, for direct pressing of starch and crosslinkers. Such starch mixtures are claimed as binders in tablet form.

[0014] D7 also describes in detail the application of bifunctional carboxylic acids, in particular adipic acid, as crosslinking agents.

D8 describes a method of spraying a phosphate-containing solution onto starch. Subsequent kneading results in a soft substance, which is heated to a temperature of at least 140 ° C. for a few more hours. The product dissolves very easily in water after cooling. Good low viscosity properties must be contrasted with the disadvantages of heterogeneous reactions.

D9 discloses the use of starch having a phosphate group to prepare a thermoplastic starch. For this purpose, natural plant starch is used. Various additions,
The properties are modified mainly by the addition of divalent cations.

D10 describes the preparation of a native starch having a phosphate group. The starch is first denatured by washing away the free electrolyte using a washing treatment with deionized water. After this, the acid part of the phosphate group is replaced mainly by divalent ions such as Mg ²⁺ or Ca ²⁺ , thus modifying the starch.

D11 is prior art mainly in the modification of starch with phosphate in suspension.

As a result of the prior art discussed and discussed herein, it is an object of the present invention to provide a starch-based raw material that allows for the production of biodegradable molded articles having excellent properties, for example, excellent mechanical properties. To provide a thermoplastic mixture.

Another object of the present invention was a method for preparing a thermoplastic mixture for extrudates or pellets and furthermore the use of said thermoplastic mixture.

These objects have been achieved by a mixture having the features of claim 1. Preferred embodiments are the subject of the dependent claims. The subject matter of claim 8 solves the problems associated with the methods that existed before the present invention. Advantageous modifications of the novel method are protected by the dependent claims dependent on the independent method claim. Claim 12 provides for use according to the invention.

The starch-based thermoplastic mixture comprises: A) 100 parts by weight (calculated after correcting the water content to zero%) of the desired natural, chemically modified starch, fermentable and / or recombinant Starch of the type and / or starch prepared by bioconversion and / or derivatives of said starch; B) if necessary up to 100 parts by weight of biologically harmless, biodegradable, thermoplastically processable A) Other high molecular substances; C
D) 10 parts by weight to at least one plasticizer in an amount in the range of half the sum of parts by weight of A) and B); E) 0.01 parts by weight to (A) ) + (
B) by providing and mixing at least one phosphate in an amount in the range of / 10 parts by weight; F) if necessary up to ((A) + (B)) parts by weight of other customary additives. In addition, the mixing of at least component E) and component A) while introducing heat and mechanical energy into the thermoplastic mixture results in excellent thermoplastic processability such that it is not easily predicted. And can be processed to obtain moldings, have excellent mechanical properties, are nevertheless easily biodegradable, and can be thermoplastically processed, for example to be rotten or compostable A mixture based on starch can be produced.

In addition, products such as moldings or films are substantially biocompatible and, in some cases, edible, paving the way for edible packaging, ie, especially for food or beverage packaging. For the purposes of the present invention, a food or beverage package may be an outer package for food or beverage that only makes temporary contact, or a tube, casing, wrapping or coating whose inner surface is in constant contact with the food or beverage. Packaging. Thus, these packages can even be consumed with food or beverages. The packaging is thus particularly suitable for fruits, eggs, cheeses, candies, cakes, biscuits or effervescent tablets, beverages, meat, sausage products or sausage-meat emulsions.

Here, the use of the moldings obtainable from the thermoplastic molding compositions according to the invention is not limited to the use in combination with temporary products, but to protect consumer goods or commercial assets during transportation or storage. It can be extended to temporary use. Special care must be taken to protect against exposure to climatic conditions, such as those encountered when transporting vehicles abroad.

Surprisingly, the use of specific additives such as phosphates, preferably polyphosphates, metaphosphates and / or polymetaphosphates under certain conditions, on the one hand, modifies the starch, on the other hand, It has been found that conventional thermoplastic processing techniques are used to achieve an effect that allows for further processing of the starch.

Under the conditions described according to the invention, it is possible for the additives according to the invention to carry out a modification reaction during processing, even at low concentrations, which has a positive effect on the properties and processability of the thermoplastic starch mixture. it can. Component A) of the novel starch mixture Component A) is an essential component of the novel mixture.

Component A) is one or more starches, one or more starch derivatives, or a mixture of starch and starch derivatives.

An important group of starches includes starch obtained from plant sources. These include tubers such as potatoes, cassava, maranta or sweet potato, seeds such as wheat, corn, rye, rice, barley, millet, oats or sorghum, chestnuts, acorns, beans, peas and other beans or bananas. Includes starch made from fruit or plant pith, for example, cycad pith.

The starch that can be used for the present invention consists essentially of various proportional amounts of amylose and amylopectin.

Particularly good results have been found in starches made especially from potatoes (eg Su
RToffena® from edstarrke or starch made from corn (eg Corn Star from National Starch).
ch) or starches characterized by a completely linear structure of polymers made from polyglucans.

The molecular weight of the starch that can be used according to the invention can vary over a wide range. Starch which can be used as a main component of the novel thermoplastic mixture is a starch consisting essentially of amylose and amylopectin having a molecular weight Mw in the range of 5 × 10 ⁴ to 1 × 10 ⁷ . Relatively long chain polymers having a molecular weight Mw of 1 × 10 ^{6 to} 5 × 10 ⁶ are preferred.

Linear polysaccharides having a molecular weight Mw in the range of 5 × 10 ² to 1 × 10 ⁵ , preferably 1 × 10 ^{3 to} 5 × 10 ⁴ , preferably polyglucans, especially 1, 4-α-D-polyglucan is also preferred.

The present invention relates to a molding composition based on starch, which is a natural plant source, and which is chemically modified, obtained by fermentation, has a recombinant source, or undergoes biotransformation (ie, biotransformation). Catalysis) also includes thermoplastic mixtures or molding compositions having the starch prepared by catalysis.

For the purposes of the present invention, “chemically modified starch” is a starch whose properties have been changed from its native state by chemical means. This is substantially achieved by a polymer-like reaction in which the starch is treated with mono-, di- or polyfunctional reagents and / or oxidants. In this case, the hydroxyl groups of the starch polyglucan are preferably converted by etherification, esterification or selective oxidation, or the modification is based on free-radical-initiated graft copolymerization of copolymerizable monomers on the starch backbone. .

Particularly chemically modified starches include starch esters such as xanthogenate, acetate, phosphate, sulfate and nitrate, starch ethers such as nonionic, anionic or cationic starch ethers, dialdehyde starch. Such as oxidized starch, carboxy starch, persulfate degraded starch and the like.

A “fermentable starch” for the purposes of the present invention is a starch obtained by a fermentation process using a natural organism, such as a fungus, algae or bacteria, or by the involvement or support of a fermentation process. Examples of fermented starches include gum arabic and related polysaccharides (gellan gum, gatch gum, karaya gum, tragacanth gum), xanthan,
Emulsan, ramsan, welan, schizophyllan, polygalacturonates,
Laminarin, amylose, amylopectin and pectins.

For the purposes of the present invention, “recombinant starch” or “recombinant starch” is in particular the power of natural organisms, such as fungi, algae or bacteria, which are not present in nature but have been modified by genetic engineering. Is a starch that can be obtained by a fermentation method or by the involvement or support of a fermentation method using an organism borrowed from the above. Examples of starch obtained by fermentation methods using genetically modified methods are amylose, amylopectin and other polyglucans.

For the purposes of the present invention, “starch prepared by bioconversion” refers, under certain conditions, to the use of biocatalysts (ie enzymes) to form monomeric bases of oligomeric saccharides, especially mono- or disaccharides. Starch, amylose, amylopectin or polyglucans prepared by the contact reaction of building blocks. Examples of starches from biocontact reactions are polyglucans and modified polyglucans, polyfructans and modified polyfructans.

Finally, the advantageous thermoplastic mixtures can also be obtained using the individual starch derivatives mentioned above. For the purposes of the present invention, "starch derivatives" and "starch derivatives" are generally modified starches, i.e. by modifying the native amylose / amylopectin ratio or by pre-gelling, partial hydrolysis or chemical induction. The changed starch.

Examples of particular derivatives of starch are oxidized starches, such as dialdehyde starch or other oxidation products having carboxyl functionality, as well as natural ionic starches (eg having a phosphate group) and ionically modified (In which case the term includes both anionic and cationic modifications).

If the starch used has very little other compounds (eg proteins, fats, oils) which do not belong to sugars (eg especially potato starch) or use ionic starch as base material or mix If and / or if the starch base used comprises polyglucans having extraordinary homogeneity in terms of structure, molecular weight and purity, for example 1,4-α-D-polyglucan prepared by bioconversion, A particularly advantageous thermoplastic mixture is obtained. For the new thermoplastic mixture, calculations are made to correct the water content to zero% for component A) or for mixtures made from component A). This means that the amount of water in component A) is determined and the appropriate amount is subtracted when it reaches 100 parts by weight, but is taken into account when the amount of component C) is reached. Component B) of the novel thermoplastic mixture starting from starch Component B) of the novel thermoplastically processable mixture is an optional component.

More specifically, this is a biologically harmless, substantially biodegradable, thermoplastically processable polymeric material other than A), which may comprise up to 100 parts by weight of the mixture. Can be present in quantity. Component B) can also be a mixture of two or more compounds of this type.

A group of substances satisfying these requirements is a group of proteins. Ingredients B) which can be advantageously used for the purposes of the present invention include gelatin, sunflower proteins, soy proteins, cottonseed proteins, groundnut proteins, plant proteins such as rapeseed proteins, plasma proteins, egg whites, egg yolks and the like.

Advantageous mixtures can also be obtained with the addition of zein, gluten (corn, potato), albumin, casein, creatine, collagen, elastin, fibroin and / or whey protein.

Other substances of interest as component B) are the polysaccharides other than starch mentioned in A).

Water-soluble polysaccharides such as alginic acid and salts thereof, carrageenans, furcellaran, guar gum, agar, gum arabic or similar polysaccharides (gatch gum, karaya gum, tragacanth gum), tamarind gum, xanthan gum, aralia gum, roxto bean gum , Arabinogalactan, pullulan, chitosan, dextrin or cellulose is preferred.

In some cases, the addition of lentinan, laminarin, chitin, heparin, inulin, agarose, galactans, hyaluronic acid, dextrans, dextrins, poly-α-caprolactones and / or glycogen may have beneficial effects.
Component C) of the novel starch mixture Component C) of the novel mixture is an essential component.

[0048] The novel mixture has from 1 to 100 parts by weight of water. If the amount of water is less than 1 part by weight, the structural breakdown and homogenization of the mixture are insufficient. If the water content exceeds 100 parts by weight, the viscosity of the mixture may be too low. An advantageous range is about 10 to 75 parts by weight of water. A range of 20 to 60 parts by weight is of particular interest. If a significant proportion of optional component B) is present in the novel mixture, this can be taken into account separately when defining the amount of water. In this case, the water content is preferably 1 part by weight to half of the total of the parts by weight of A) and B). If the water content is about half of the parts by weight of A) and B), the thermoplasticization of the entire mixture is particularly good. A preferred water content is about 5 to about (A) + (B) / 2 parts by weight, and 10 to (A) + (B)
A water ratio of / 3 parts by weight is particularly useful.

These preferred ranges are for the ideal plasticization of the mixture, ie for the destruction of starch,
Figure 3 shows the homogenization of the mixture and also the thermoplasticization of the mixture.

The amount of water C) includes both the water actually added and the water from other components,
In particular, the amount of water present or associated in component A) and the amount present or associated in component E) must be taken into account in the calculations.

Other aspects of the nature of component C) are not material. Demineralized water, deionized water, or equally good mains water or other source water can be used provided that the content of salts or other foreign matter in the water is acceptable for the intended application. Component D) of the new starch mixture Component D) must be present in the new mixture.

The amount of component D) is particularly important, that is, it can be freely selected only within the specified range. One or more plasticizers are present in the novel composition from 10 parts by weight to A) and B).
Is present in an amount in the range of half the sum of the parts by weight. The content of the compound to be plasticized is 10
If it is less than parts by weight, plasticization is insufficient even with relatively large amounts of mechanical and / or thermal energy. If the plasticizer content exceeds half the sum of parts A) and B) parts by weight, there is no significant improvement in the plasticization of the mixture.

Preferred amounts of plasticizer are in the range from 12.5 to (A) + (B) / 2 parts by weight, with a particularly useful plasticizer content being from 15 to (A) + (B) / 4 parts by weight. Within the range of the part. For the purposes of the present invention, the terms plasticizing agent, plasticizer, plasticizing agent and elasticizer have essentially the same meaning as the term plasticizer.

It usually has a low vapor pressure and physically interacts with component A) and, if present, B) and preferably not only due to its solvent or swelling power, but also in the absence thereof Inert, preferably organic, substances which form a homogeneous system with the components without a chemical reaction can be used. Component D) used according to the invention preferably lowers the freezing point of the mixture, improves deformability, increases elasticity, lowers hardness,
If necessary, increase the adhesion.

According to the present invention, preferred plasticizers are odorless, colorless, light-fast, cold- and heat-resistant, have little moisture absorption, are water-resistant, harmless to health, are flame-resistant and as far as possible It is non-volatile, exhibits a neutral reaction, is miscible with polymers and auxiliaries, and has good gelling performance. In particular, the plasticizer must have compatibility, gelling capacity and plasticizing action with component A) and, if used, B).

The components used according to the invention as components D) must also be characterized by a low migration, which is of particular importance for the applications of the shaped articles according to the invention in the food and beverage sector.

Examples of particularly preferred plasticizing components D) are dimethyl sulfoxide, 1,3-butanediol, glycerol, ethylene glycol, propylene glycol, diglyceride, diglycol ether, formamide, N, N-dimethylformamide, N-methylformamide , Dimethylacetamide, N-methylacetamide and / or N, N'-dimethylurea.

Other particularly useful materials are polyalkylene oxides, glycerol mono-, di-
Or triacetate, sorbitol and other sugar alcohols such as erythritol, sugar acids such as gluconic acid, polyhydroxycarboxylic acids, sugars such as glucose, fructose or sucrose, and also citric acid and its derivatives. Component E) of the novel thermoplastic mixture based on starch The component E) is essential for the novel mixture.

The amount of component E) present in the novel mixture is of particular importance. The new mixture is 0.
Component E) in an amount of from 01 parts by weight to (A) + (B) / 20 parts by weight. Useful amounts are at least 0.1 parts by weight, preferably 0.1 to (A) + (B) / 20 parts by weight.

If the amount of component E) is too low, the mechanical properties of the moldings obtainable from the novel mixtures are poor. When the amount exceeds (A) + (B) / 10 parts by weight, the plasticization of the molding composition is impaired.

According to the invention, the phosphate is component E). For the purposes of the present invention, phosphates are various salts or esters of phosphoric acid, although various salts of phosphoric acid are much more preferred for the present invention. According to the invention, the component E) used can comprise one or more salts and / or esters of various phosphoric acids, so that one or more phosphates can form component E).

The compounds which can be used with advantage as component E) are, in particular, those of the formula M^IH_TwoPO_Four(For example, NaH_TwoPO_Four) And M^II(H_TwoPO_Four)_Two[For example, Ca (H_TwoPO_Four)_Two An orthophosphate of the general formula M^I _TwoHPO_FourOr M^IIHPO_FourThe second class Ortori
Phosphate (eg K_TwoHPO_Four, CaHPO_Four) Or the general formula M^I _ThreePO_FourOr M ^II _Three (PO_Four)_TwoTertiary orthophosphate [eg Na_ThreePO_Four, Ca_Three(PO_Four)_Two ] (Where M is⁺Monovalent cations such as NRR'R "R" "wherein R, R ', R" and R "" are the same or different independently of one another and are hydrogen, (C₁-C₈) Al
Kill (linear or branched), (C_Four-C₈) Aryl, preferably phenyl, al
Potassium metal ion, preferably Na⁺Or K⁺) And M^IIIs divalent cation, preferred
Or alkaline earth metal ions, particularly preferably Ca²⁺).

Also of particular interest as component E) are the group of condensed phosphates which are derived from acidic salts of orthophosphoric acid and generate water when heated to produce water. These can be further subdivided into metaphosphate (strain name: cyclopolyphosphate) and polyphosphate (strain name: catenapolyphosphate).

Preferred examples are Graham's, Chlor's and Madrel's salts, as well as molten or calcined phosphates.

[0065] Particularly useful modifiers E) are, in particular a metaphosphates of general formula ^{_{M I n [P n O 3n}} ] ( wherein, M ^I is a monovalent cation, preferably a metal ion, typically an alkali metal ion , Preferably Na ⁺ or K ⁺ , or ⁺ NRR′R ″ R ″ ″, wherein R 1, R ′, R ″ and R ″ ″ are the same or different independently of one another and are hydrogen, (C ₁ -C ₈ alkyl (linear or branched), or (C ₄ -C ₈ ) aryl, preferably phenyl), and n is a positive integer and preferably in the range of 3 to 10.) , even more preferably n is M ^I is Natoriumuma other at 3, 4 or 5 is a metaphosphate potassium. most preferably sodium trimetaphosphate, and sodium Pentametarin acid tetrametaphosphate acid.

[0066] In preferred mixture also obtained when the polyphosphate of the general formula ^{_{M I n + 2 [P n}} O 3n + 1] or ^{_{M I n [H 2n P n}} O 3n + 1] ( wherein, M ^I is a monovalent cation, preferably a metal ion, advantageously an alkali metal ion, preferably Na ⁺ or K ⁺ , or ⁺ NRR′R ″ R ″ ″ (where R, R ′, R ″ and R ″ ″ independently of one another are the same or different and are hydrogen, (C ₁ -C ₈ ) alkyl (linear or branched), or (
C ₄ -C ₈₎ aryl, preferably phenyl), and n is a positive integer greater than 2). Of these, sodium and potassium polyphosphates with n> 10 are preferred.

[0067] mixture with advantageous properties, as component E), the general formula ^{_{M I n + 2 [P n}} O 3n + 1] can also be obtained by using polyphosphates (wherein, M ^I is Monovalent cations, preferably metal ions, effectively alkali metal ions, preferably N
a ⁺ or K ⁺ , or ⁺ NRR′R ″ R ″ ″, wherein R, R ′, R ″ and R ″ ″ are the same or different independently of one another and are hydrogen, (C ₁ -C ₈ ) alkyl (linear or branched), or (C ₄ -C ₈₎ aryl, preferably phenyl), and n is a positive integer from 3 to 10). Among these, pentasodium tripolyphosphate is particularly preferred.

In a particular embodiment, the novel thermoplastic mixtures have the further characteristic that component E) is an alkali metal metaphosphate or an alkali metal polyphosphate.

When component E) is sodium trimetaphosphate, sodium metaphosphate, sodium polyphosphate and / or sodium hexametaphosphate, preferably sodium polyphosphate, another advantageous modification of the novel thermoplastic mixture is obtained.

The phosphate can have various degrees of hydration. The proportion of component E) in the thermoplastic mixture is relatively small, so that when determining parts by weight of E) component C)
Is always present, so its moisture content is generally meaningless and not determined. Component F) of the novel starch mixture Component F) of the novel starch mixture is optional, ie component F) may not be present in the novel mixture.

This can be one or more substances which can be used together as component F) in amounts of up to 200 parts by weight, preferably up to 100 parts by weight.

The usual additives include fillers, lubricants other than the plasticizers described in D), softeners, pigments,
There are dyes and release agents.

Examples of suitable fillers are synthetic polymers that are virtually soluble in the mixture, such as Mit
Sui's Racea®, Boehringer Ingelheim
Lactic acid-based polymers such as Resomer (R), and other lactic acid-based polymers and Wako Pure Chemical Industries L
td. , Medisorb Co .; , Birmingham Polymers
Inc. , Polyscience Inc. , Purac Biochem
A similar lactic acid polymer from BV, Ethicon, Cargill or Chronopo. Clearly, this list cannot be completely comprehensive.

Other polyesters, preferably made from physiologically harmless hydroxycarboxylic acids such as polyhydroxybutyric acid-co-valeric acid, may also be used, in particular those having the trademark Biopol®.

The addition of at least one inorganic filler such as magnesium oxide, aluminum oxide, SiO ₂ , TiO _{2 and the} like is also proposed.

Organic or inorganic pigments, such as so-called pearlescent pigments, which are biocompatible, ie can be classified as harmless to living organisms, are particularly suitable for coloring the mixture. These are based on the silicate structure and can therefore be basically classified as edible and are used in amounts of 0.001 to 10 parts by weight.

Particularly suitable substances for improving the flowability are animal or vegetable fats and / or lecithins which are preferably used in the form of hydrogenation. These fats and other fatty acid derivatives preferably have a melting point above 50 ° C.

To reduce the hydrophilicity and thus the sensitivity of the thermoplastically processable mixture to water during and after processing, a minor amount of cross-linking of the mixture to chemically modify the starch is carried out. Agents can be added. For this purpose, it is preferred to use up to 5 parts by weight of alkylsiloxanes.

Suitable crosslinking agents are, in particular, dibasic or polybasic carboxylic acids, furthermore their anhydrides, dibasic or polybasic carboxylic acid halides, dibasic or polybasic carboxylic acid amides. , A dibasic or polybasic inorganic acid derivative other than component E),
Epoxides, formaldehyde and / or urea derivatives, divinyl sulfones, isocyanates, oxo compounds and / or cyanamides. These compounds are particularly suitable for chemical modification after thermoplastic processing and can therefore contribute in particular to further improvements in mechanical properties.

While introducing heat and mechanical energy into the thermoplastic mixture, at least component A
) And component E), the components A) to F) of the new mixture are mixed with one another.

It is preferable to work simultaneously at high temperatures and at the same time simultaneously introduce mechanical and thermal energy by applying shear forces to the thermoplastic mixture to be plasticized, based on starch.

Good homogeneity of the mixture is generally obtained at relatively high temperatures. However, the temperature should not be too high in order to avoid unnecessary discoloration or decomposition of the molding composition. In this situation, mixing at a temperature in the range of less than 60 ° C to 200 ° C is a preferred form of thermoplastic mixing according to the present invention.

Basically, the homogeneity of the mixture increases with the work to be introduced. This means that as more work is introduced into the mixing assembly, the homogeneity of the thermoplastic starch mixture improves. Thus, a further modification of the present invention provides a mixture that can be obtained by mixing using a powerful shear mixing arrangement. The energy introduced into the mixture can be obtained, inter alia, from the work performed by the processing machines used. For example, devices in which the plasticizing device has a torque in the range of 5 to 300 Nm (1 Newton meter) are particularly suitable for this method. Torques in the range from 10 to 100 Nm have been found to be advantageous for this method. It is preferable to carry out a method having a torque in the range of 20 to 40 Nm.

When the components of the new mixture are mixed and homogenized on a plastics processing machine such as an extruder, kneader or similar arrangement, a particularly advantageous absorption of heat and / or mechanical energy is achieved by the mixture. Is done. The process can preferably be carried out in a single or twin screw extruder, which is preferably assembled from individual barrels with a temperature regulating jacket. There are no restrictions on the screw design. A conveying device (with or without a thrust edge), a kneading device and / or a mixing device can be present. Furthermore, it is often possible and advantageous to have a flow-inhibiting or reversing conveying device in some part or section of the extruder in order to adjust and control the residence time and the properties of the mixture.

The order of mixing the components A) to F) may be of particular importance. Accordingly, the present invention provides A) 100 parts by weight (calculated after correcting the water content to zero percent) of the desired natural, chemically modified starch, fermentable and / or recombinant starch and / or prepared by bioconversion. Starch and / or a derivative of said starch;
B) up to 100 parts by weight, if necessary, of a physiologically harmless, biodegradable, thermoplastically processable polymeric substance other than A); C) 1-100 parts by weight of water; D) 10 parts by weight. Parts) at least one plasticizer in an amount half the sum of parts by weight of A) and B); E) at least an amount in the range of 0.01 parts by weight to (A) + (B) / 10 parts by weight. 1
F) if necessary, up to ((A) + (B)) parts by weight of other conventional additives; and add component E) to components A) to D), By adding also F), if necessary, a process for the preparation of a starch-based thermoplastic mixture by mixing with one another is provided, in which heat and mechanical energy are introduced into the thermoplastic mixture and preferably Causes the mixing of at least component E) and the remaining components while applying shear forces to the thermoplastic mixture simultaneously with the action of the high temperature.

The nature and effect of this method differ significantly from the known prior art. Previously, when phosphoric acid or its salts or esters were used as modifiers in preparing thermoplastic mixtures based on starch, starch was exclusively starch granules that would always be directly modified, otherwise, Crosslinking was achieved using a heat treatment followed by a large addition in terms of parts by weight of the phosphate, which produces a molding composition that can no longer be thermoplastically processed.

In contrast, the new method ensures that the modification is not only the surface of the starch granules, but also the entire starch molecule, preferably the main chain of the starch. This gives a variety of products, the excellent properties of which were not easily predictable.

The reaction with starch or starch derivatives or mixed proteins by addition of additional components E) under alkaline or acidic conditions during processing in a homogenizing or mixing arrangement, for example a kneader or extruder, results in a cross-linking reaction. Causes few properties. That is, the main factor is modification of the polymer main chain.

The differences from the known starch phosphates from the prior art can also be manifested, for example, in the degree of substitution.

The number of hydroxyl groups per glucose unit of starch replaced by another functional group (phosphate) is called the degree of substitution DS.

There are three free hydroxyl groups per glucose unit. Therefore, the degree of substitution is 0
. Ranges from 0 to 3.0.

Therefore, the substitution degree DS is a purely statistical variable. A degree of substitution of 1.0 only means that an average of one hydroxyl group per glucose unit was replaced by a substituent. Thus, a DS of 1.0 does not necessarily mean that each glucose unit has exactly one substituent with two residual unsubstituted hydroxyl groups.

For example, it is known that native starch itself can contain phosphate groups. In this case, the degree of substitution is in the region of about 0.001. Thus, from a purely statistical point of view, one phosphate group appears in the polymer for about every 300 glucose units.

Thus, in known methods of modifying starch as granules, and thus substantially only on the surface, a degree of substitution DS in the range of about 0.001 to 0.01 can be assumed.

However, according to the invention, modification with the phosphate (component E)) achieves a significantly higher DS value during plasticization. This is approximately> 0.01-1.0. The DS of the component A) modified according to the invention is preferably approximately 0.05 to 0.5, in particular 0.1 to 0.3 for convenience. By the addition of plasticizers, which themselves have a high proportion of hydroxyl groups or other groups which grow hydrogen bridges on carbon atoms, the reaction of the phosphate, with the proper progress of the reaction, furthermore the binding of the plasticizer to the starch backbone. It can also be achieved, especially during processing, which reduces the migration of plasticizer from the mixture. However, this does not eliminate the plasticizing effect of the plasticizer needed in the first place to break the starch, i.e. cut open the starch granules. However, this possible interpretation of the reaction taking place and producing surprising results does not exclude other possible interpretations.

The novel thermoplastic molding compositions can be processed by known processing methods to give products. For example, it can be pelletized in the first step.

The invention therefore also provides the pellets obtainable from the thermoplastic mixture by extrusion and pelletization according to the invention.

The thermoplastic pellets can be directly or furthermore thermoplastically processed to obtain molded articles or films having good biodegradability and good properties, preferably good mechanical properties.

Finally, the invention also encompasses the use of thermoplastic mixtures for producing shaped articles or films.

In this case, the thermoplastic molding compositions and the moldings and films obtained by further processing achieve both excellent heat resistance and improved flame retardancy as a result of the mixing of the essential components E). I do.

The new products thus cover a wide variety of possible applications. These applications include, in particular, adhesives for paper and cardboard, molded articles produced by injection molding, especially rods, tubes, bottles, capsules, pellets, food or beverage additives, coatings or free-standing foils, and also in the form of laminates. , Including films, especially films, packaging materials, bags, and slow release agents for the controlled release of active substances, especially drugs, pesticides or other active substances used in agriculture, fertilizers, fragrances, etc. .
Here, the release of the active substance can take place from foils, films, tablets, particles, microparticles, rods or other extrudates or other moldings.

More preferred uses are food or beverage packaging, especially sausage casing or cheese wrapping, absorbents, powders and the like.

In a particular embodiment, the novel thermoplastic mixtures are used for producing shaped articles for the controlled release of active substances, for example tablets or dragees.

Another suitable and particularly advantageous application of the novel thermoplastic mixtures relates to the production of solid moldings, hollow moldings or moldings suitable for producing a combination thereof. Another excellent use of the novel thermoplastic mixtures is for the production of films for agricultural use.

Another particular variant of the invention is the use of a thermoplastic mixture for producing a film for use in food or beverages.

Another specific use of the thermoplastic mixture is for the production of films for use as outer packaging for surrounding food or beverages.

One further very advantageous application of the novel thermoplastic mixtures is for the production of films for use as food or beverage packaging, wherein complete surface contact between the packaging and the food or beverage is obtained. is there.

A final particularly useful application of the novel thermoplastic mixtures is for the manufacture of flat or tubular films for use as sausage or cheese food casings or wrappings.

For the present invention, the use of thermoplastic mixtures as temporary protective films for industrial consumer goods is preferred.

The following examples illustrate the content of the present invention. Example 1 Preparation of a thermoplastically processable formulation made from potato starch and sodium polyphosphate, gum arabic and glycerol: The compound is prepared in a commercial kneading assembly (Bravenender kneader). The kneading assembly is heated to 100 ° C. The kneading assembly in operation is filled with 30 g of potato starch (Toffena from Suedstaerke). 0.9 g of NaCO ₃ is dissolved in 10 g of water and added to the potato starch in the kneader. Homogenize the mixture. This procedure takes about 3 minutes. Then add 9 g of gum arabic at once. The mixture is homogenized again. 9 g of glycerol are then added in small portions (about 3 equal portions, with a kneading interval of 2 minutes between each addition). After a further 2 minutes, 1.2 g of sodium polyphosphate (Riedel de Haen) dissolved in 5 ml of water are added. The whole mixture is kneaded again for another 2 minutes. The composition is removed while the device is still hot. The product is an opaque homogeneous composition with a slight yellow tint. The thermoplastic composition can be further processed after cooling.

The foil obtained by thermoplastic processing of the resulting composition is transparent and has good mechanical strength. Comparative Example 2 Preparation of a thermoplastically processable formulation made from potato starch with sodium polyphosphate and gum arabic: A mixture is prepared as described in Example 1. The only difference in the mixing specifications is that glycerol is not used as a plasticizer.

After completion of homogenization, the composition is removed while the device is still hot. The product tends to be brittle with a slightly brownish opaque homogeneous composition. The further processing, in particular for obtaining films or foils, can only be realized after adding water to the molding composition beforehand. Example 3 Preparation of a thermoplastically processable formulation made from casein and potato starch and sodium polyphosphate: The compound is prepared in a commercial kneading assembly (Brabender kneader). The kneading assembly is heated to 100 ° C. 20 g of casein and 10 g of potato starch (Toffen from Sudestaerke) are added to the kneading assembly in working condition.
Fill a). 1.2 g sodium polyphosphate (Ri dissolved in 5 ml water)
edel de Haen) immediately. The mixture is homogenized for 3 minutes. 6 g of glycerol are then added in portions (about 3 equal portions, with a kneading interval of 2 minutes between each addition). The mixture is homogenized for a further 2 minutes. The resulting formulation is a slightly yellowish thermoplastically deformable composition that can be further processed immediately after removal from the kneading assembly or after cooling while still hot.

The foil obtained by thermoplastic processing is transparent and has good mechanical properties in terms of elongation at break and tear resistance. Example 4 Preparation of a thermoplastically processable formulation made from potato starch and sodium polyphosphate: This method is similar to that described in Example 1. Kneading assembly device (Bravende
r) is heated to 100 ° C. The working kneading assembly is filled with 30 g of potato starch (Toffena from Suedstaerke). 0.9 g of Na ₂ CO ₃ dissolved in 10 ml of water are added immediately. The mixture is homogenized for 3 minutes. 15 g of glycerol are then added in small portions (about 3 equal portions, with a kneading interval of 2 minutes between each addition). After the mixture has been homogenized for a further 2 minutes, 0.15 g of sodium polyphosphate (Riedel de Haen) in 5 ml of water is added. After obtaining a more homogeneous phase, the experiment ends. The product is a slightly yellowish thermoplastically deformable composition that can be further processed after cooling.

[0114] The foil obtained by thermoplastic processing is transparent and has very high mechanical strength.
The thickness of the film is in the range of 100-150 μm. Due to the flexibility of the film, it can be further processed, for example filled with food. Example 5 Preparation of a thermoplastically processable formulation made from potato starch and casein and sodium polyphosphate: The method is as described in Example 1. The kneading assembly is heated to 120 ° C. A working kneading assembly (Brabender) is filled with 21 g of potato starch (Toffena from Suedstaerke) and 9 g of casein. 0.9 g of NaCO ₃ is dissolved in 10 g of water and added to the mixture of casein and potato starch in the kneader. Homogenize the mixture. This procedure takes about 3 minutes. Then 1.5 g of Pluronic F68 in 10 ml of water and then 6 g of glycerol are added sequentially. The mixture is homogenized again. After about 2 minutes, 5m
1.2 g of sodium polyphosphate dissolved in 1 l of water (Riedel de Ha
en). The whole mixture is kneaded again for another 2 minutes. The composition is removed while the device is still hot. The product is a very white homogeneous composition. The thermoplastic composition can be further processed after cooling.

The films obtained by thermoplastic processing are opaque. The thickness of the film is about 160-200 μm. In addition to the film thickness obtained by compression molding,
The mechanical strength shows some brittleness. Thus, for applications in the food or beverage field, further processing requires the addition of water. Example 6 Preparation of a thermoplastically processable formulation made from casein and corn starch and sodium polyphosphate: This method is similar to that described in Example 1. Kneading assembly device (Brabend
er) to 100 ° C. The working kneading assembly is filled with 24 g of casein and 6 g of corn starch. After a short time, 10 ml of water and a further 4 g of glycerol are added. After an even shorter homogeneous phase is obtained, 0.8 g of sodium polyphosphate (Riedel de Haen) in 2 ml of water are added. The experiment ends after a more homogeneous phase has been obtained. The product is a slightly yellowish thermoplastically deformable composition that can be further processed after cooling. The foil obtained by thermoplastic processing (compression molding) is slightly opaque and has excellent mechanical strength.
The thickness of the film is in the range 170-190 μm. Because the film is flexible, it can be further processed, for example, filled with food. Example 7 Preparation of a thermoplastically processable formulation made from casein and potato starch and sodium polyphosphate: This method is similar to that described in Example 1. Kneading assembly device (Brabend
er) to 100 ° C. 15 g of casein and 15 g of potato starch (for example, Tof from Suedstaerke) are added to the kneading assembly in the working state.
fena). After a short time, 1.5 g of citric acid in 10 ml of water and a further 6 g of glycerol are added. After a short time homogeneous phase is obtained, 5m
1.2 g of sodium polyphosphate in 1 l of water (Riedel de Haen)
Add. After further homogenization is obtained, the experiment ends. The product is a homogeneous, yellowish solid composition that can be further processed after cooling.

The foil obtained by thermoplastic processing (compression molding) has a yellow tint and is transparent or slightly opaque. The film is very thin in the range of 80-100 μm. Example 8 Production of a film from the thermoplastic molding composition prepared in Examples 1 to 7 using a compression molding method: To process the thermoplastic molding composition, the following method is used. Commercial Sc
A hwaventhan (Polystat 300S) press is used. The press is preheated to 100 ° C. The preparation of the sample consisted of two fiber-reinforced polytetrafluoroethylenes (PTFE, Te) held apart by a metal frame of about 100 μm thickness.
Flon: a "sandwich method" between sheets. During preparation, about 2 g of the composition prepared in the kneader is placed in the center of the lower sheet. The sample is kept at a temperature of 100 ° C. and a pressure of 1 t for 5 minutes. The sample is then taken at a pressure of 10 t
Compression molding at 0 ° C. for 5 minutes. This corresponds to a pressure of 200 bar. Release the pressure and transfer the sample to another press to cool. This is Robert Fuchs
Hydraulische Maschinen und Werkzeuge
It is a water-cooled press. A pressure of 50 bar is applied during the cooling process for 2 minutes. The sample is then removed and used for the next test. It has to be noted that, due to the hydrophilicity of the materials used, storage in air causes an aging phenomenon which can be attributed to fluctuations in water content. Example 9 Preparation of a thermoplastically processable formulation made from corn starch with a high content of sodium polyphosphate: This compound is prepared in a commercial kneading assembly (IKA Duplex kneader). The kneading assembly is heated to 100 ° C. 150g in the kneading assembly in working condition
Of corn starch (from National Starch) and 45 g of glycerol. 5.0 g of NaCO ₃ is dissolved in 50 g of water and added to the corn starch in the kneader. Homogenize the mixture. This treatment is about 5-10
Takes some time, during which time the mixture becomes glassy. Then 15 g of sodium triphosphate (Riedel de Haen) dissolved in 25 ml of water are added. The whole mixture is kneaded again for a further 5 minutes. The composition is removed while the device is still hot. Comparative Example 10 Preparation of thermoplastically processable formulations made from corn starch without sodium polyphosphate: These compounds are prepared in a commercial kneading assembly (IKA Duplex kneader). The kneading assembly is heated to 100 ° C. 1 for kneading assembly in working condition
50 g corn starch (National Starch) and 4
Charge 5 g glycerol. 5.0 g of NaCO ₃ is dissolved in 50 g of water and added to the corn starch in the kneader. Homogenize the mixture. This procedure takes about 5-10 minutes, during which time the mixture becomes vitreous. The whole mixture is kneaded again for a further 5 minutes. The composition is removed while the device is still hot. Example 11 Preparation of a Film from a Starch-Based Thermoplastic Material Using the Compression Molding Method: The thermoplastic molding composition is further processed to obtain a film using the compression molding method described herein. In this case, a commercially available Schwaventhan (Polysta)
t300S) Use a press. The press is preheated to 100 ° C. The sample preparation uses a "sandwich method" between two fiber reinforced Teflon sheets held apart by a metal frame about 100 μm thick. During preparation, about 2 g of the composition prepared in the kneader is placed in the center of the lower sheet. The sample was prepared at a temperature of 100 ° C. and a pressure of
Hold for a minute. The sample is then compression molded at 100 ° C. for 5 minutes at a pressure of 10 t. This corresponds to a pressure of 200 bar. Release the pressure and transfer the sample to another press to cool. This is Robert Fuchs Hydraulisch
e A water-cooled press manufactured by Maschinen und Werkzeuge. 2
During the cooling operation for one minute, a pressure of 50 bar is applied. Example 12 Test on heat resistance of a film produced in the same manner as in Example 11 from the thermoplastic molding compositions from Example 9 and Comparative Example 10: A film with dimensions of 5 cm × 5 cm is placed on a ring with an inner diameter of 3 cm. , Held by metal clamps so as not to be affected by slight air movement. As a result of holding the ring horizontally by the holding rod connected to the ring, the film was removed from the bench by 2
Place at 0 cm height. An open flame having a height of 1 to 2 cm is placed on the lower surface of the ring to supply the same energy per unit time during the whole test. Here, the upper limit of the open flame is 5 cm ± 0.5 cm away from the film. A stopwatch is used to measure the time required to achieve pyrolysis of the fill over 50% of the surface of the ring covered with the thermoplastic film. Calculate the average of 10 measurements each. Film from Example 9 with sodium triphosphate: 25 ± 3 seconds. Film from Example 10 without sodium triphosphate phosphate: 16 ± 3 seconds. Other advantages and aspects of the present invention are set forth in the following claims.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Böm, Gitte, Federal Republic of Germany-60439 Frankfurt am Main, Im Burgfeld 243 (72) Inventor Schuss, Silk, Federal Republic of Germany-Day 56412 Ruppacher- Goldhausen, Hauptstrasse 30

Claims (19)

[Claims] 1. A starch-based thermoplastic mixture for the production of a biodegradable molded article, comprising: A) 100 parts by weight (calculated after correcting the water content to zero%) of the desired Native, chemically modified starch, fermentable and / or recombinant starch and / or starch prepared by bioconversion and / or derivatives of said starch;
B) If necessary up to 100 parts by weight of a physiologically harmless, biodegradable, thermoplastically processable polymeric substance other than A); C) 1 to 100 parts by weight of water; D) 10 parts by weight. E) at least one plasticizer in an amount of half of the total parts by weight of A) and B); E) at least 1 in an amount in the range of 0.01 parts by weight to (A) + (B) / 10 parts by weight.
F) having excellent mechanical properties which can be obtained by preparing and mixing, if necessary, up to ((A) + (B)) parts by weight of other conventional additives; The above-mentioned thermoplastic mixtures, in which the mixing of at least component E) and component A) is carried out by introducing heat and mechanical energy into the thermoplastic mixture. 2. The thermoplastic mixture according to claim 1, wherein the amount of component E) present is at least 0.1 part by weight. 3. The thermoplastic mixture as claimed in claim 1, wherein the amount of component E) present is at most (A) + (B) / 20 parts by weight. 4. The thermoplastic mixture according to claim 1, wherein component E) is an alkali metal metaphosphate or an alkali metal polyphosphate. 5. The thermoplastic mixture according to claim 4, wherein component E) is sodium trimetaphosphate, sodium metaphosphate, sodium polyphosphate and / or sodium hexametaphosphate, preferably sodium polyphosphate. 6. The thermoplastic mixture according to claim 1, which can be obtained by mixing at a temperature in the range from> 60 ° C. to 200 ° C. 7. It can be obtained by mixing using a mixing assembly having a high shear plasticizer, wherein the plasticizer has a torque in the range of 10 to 100 Nm, preferably 20 to 40 Nm. 7. The thermoplastic mixture according to claim 1, which can be achieved. 8. A process for the preparation of a starch-based thermoplastic mixture, comprising: A) 100 parts by weight (calculated after correcting the water content to zero%) of the desired natural, chemically modified starch. Starch prepared by fermentative and / or recombinant starch and / or bioconversion and / or derivatives of said starch;
B) If necessary up to 100 parts by weight of a physiologically harmless, biodegradable, thermoplastically processable polymeric substance other than A); C) 1 to 100 parts by weight of water; D) 10 parts by weight. E) at least one plasticizer in an amount that is half the sum of parts by weight of A) and B); E) at least one of an amount in the range of 0.01 parts by weight to (A) + (B) / 10 parts by weight.
F), if necessary, up to ((A) + (B)) parts by weight of other customary additives; add component E) to components A) to D) and, if necessary, Intermixing, which also includes the addition of component F), whereby at least the mixing of component E) with the remaining components introduces heat and mechanical energy, and preferably takes place simultaneously with the action of high temperatures and the thermoplasticity A process for producing a thermoplastic mixture as described above, which is carried out with the action of a shear force on the mixture. 9. Pellets obtainable from the thermoplastic mixture according to claim 1 by extrusion and pelletizing. 10. A biodegradable molded article or film having excellent mechanical properties, comprising the thermoplastic mixture according to any one of claims 1 to 7. 11. Use of the thermoplastic mixture according to claim 1 for producing molded articles or films. 12. A process according to claim 1, for producing a shaped article for the controlled release of an active substance.
Use of a thermoplastic mixture according to any one of the preceding claims. 13. Use of a thermoplastic mixture according to any one of claims 1 to 7 for the production of a solid molded article, a hollow molded article or a molded article of a combination of both. 14. Use of a thermoplastic mixture according to any one of claims 1 to 7 for producing agricultural films. 15. A method according to claim 1, for producing a food or beverage film.
Use of a thermoplastic mixture according to any one of the preceding claims. 16. Use of a thermoplastic mixture according to any one of claims 1 to 7 for producing a film for external packaging of foods or beverages. 17. A method for producing a film for use as a food or beverage package, wherein there is complete surface contact between the package and the food or beverage.
Use of the thermoplastic mixture according to any one of items 1 to 7. 18. Use of a thermoplastic mixture according to any one of claims 1 to 7 for producing flat or tubular films for use as sausage or cheese food casings or wrappings. 19. The method according to claim 1, which is used as a temporary protective film for industrial consumption materials.
Use of the thermoplastic mixture according to any one of items 1 to 7.