WO2000002459A1

WO2000002459A1 - Foil for air-dried or smoked food products

Info

Publication number: WO2000002459A1
Application number: PCT/EP1999/004314
Authority: WO
Inventors: Aktiengesellschaft Basf
Original assignee: Götz, Walter; Hanelt, Rainer; Skupin, Gabriel
Priority date: 1998-07-08
Filing date: 1999-06-22
Publication date: 2000-01-20
Also published as: DE19830389A1

Abstract

The invention relates to the utilization of shaped materials based on at least one biologically degradable polyactide or polyester or the mixtures thereof for producing foils for air-dried or smoked food products. The invention also relates to a method of production of said foils and biaxially oriented and thermofixed tubular films from a shaped material based on at least one biologically degradable polyactide or polyester or the mixtures thereof.

Description

Foils for air-dried or smoked foods

description

The present invention relates to the use of molding compositions based on at least one biodegradable polylactide or polyester or their mixtures for the production of films for air-drying or smokable or air-rocking and smokable foods. In addition, the present invention relates to the foods with these films, processes for producing these films and the films themselves. Preferred embodiments can be found in the subclaims and in the description.

The requirement for casing material for sausages is far above the available amount of natural intestine. Natural intestine also has to be laboriously cleaned and has the further disadvantage that its diameter and wall thickness are not uniform and are therefore only poorly suited for industrial processing. For these reasons, artificial casings were developed.

Packaging for sausages that are cooked or scalded should keep the moisture in the food, be as gas-tight as possible and enclose the food without wrinkles after it has cooled. In contrast, foils for air-drying and / or smoked foods must just leak the water contained in the food and allow the smoke flavors to penetrate. You must also be chemically inert to any liquid smoke that may be used alone or with other smoke. In contrast to scalded and cooked sausages, air-dried or smoked goods can have a wrinkled surface. It is also often desirable that they set up fine mold, which is precisely what is to be prevented for cooked and cooked sausages. While there are a number of artificial casings for cooked and scalded sausages, either natural casings, collagen films or cellulose-fiber casings are generally used for smoked goods.

Both collagen and cellulose fiber casings have to be obtained in a complex and environmentally harmful process, since they have to be freed from the accompanying substances (slaughterhouse waste from collagen and lignin from cellulose).

Sausage casings containing polyester are known in the field of cooked and scalded sausages. For example, DE-A 272 42 52 describes multilayer casings, one of which can be made of a polyester. DE-A 176 980 sausage shells for boiled and cooked sausages, which consist of a mixture of a polyamide and from 5 to 70 wt .-% of a polyester. Polyesters which are used are polyethylene terephthalic acid esters or copolyesters based on terephthalic acid and isophthalic acid, which may also contain small amounts of aliphatic dicarboxylic acids as monomeric building blocks. According to this document, proportions of up to 25% by weight are preferred if wrinkle-free casings are to be obtained. With larger proportions of polyester, the film deteriorates and tends to splice. Smokable plastic casings for cooked and cooked sausages made of polyamides can be found in DE-A 34 26 723. Due to their high water and oxygen diffusion barriers, these are not suitable for air-drying foods. EP-A 709 030 describes casings for all types of sausages which consist of a mixture of thermoplastic processable starch and up to 50% by weight of a polyester. However, these sausage casings have the disadvantage that the starch used must be made processable with plasticizing agents. Furthermore, the starch smell ("bakery smell") adheres to the film during manufacture, but also later. This is often undesirable for sausages. Another disadvantage of these films is that their mechanical properties and strength depend strongly on the ambient humidity.

It was therefore an object of the present invention to find films which are suitable for producing packaging for food, which are air-dried and / or smoked and which do not have the disadvantages of the prior art mentioned. Furthermore, films should be made available which have good mechanical properties, in particular do not tear when filled under pressure, but which are easy to peel.

This task is accomplished by using the molding compounds defined at the beginning.

The molding compositions which can be used according to the invention are based on at least one biodegradable polylactide or polyester, ie they can be based on one or a mixture of two or more different polylactides or polyesters or on a mixture of one or more polylactides with one or more polyesters. In the context of the invention, biodegradable is understood to mean that these polymers can largely be degraded hydrolytically and / or oxidatively by microorganisms such as bacteria, yeasts, fungi or algae by means of enzymes. Homopolymers of lactic acid can be used as polylactides (a). However, it is also possible to use copolymers, including statistical or block copolymers of lactic acid.

The lactic acid can be produced artificially or e.g. from corn, beets, cane sugar or tapioca. Both L and D lactic acid or mixtures thereof can be considered as monomers. In addition, their derivatives, preferably their C 1 -C 8 -alkyl esters, including preferably methyl lactate, ethyl lactate or n-butyl lactate, can be used for the preparation of the lactic acid-based polymers. In addition, the lactic acid halogens, such as the lactic acid chlorides, can also be used as monomers. In the preparation of the polymers, it is also possible to start from the 011 gomers of lactic acid or its cyclic derivatives, such as D- or L-dilactide (3, 6-dimethyl-l, 4-dioxane-2, 5-dione).

Other suitable comonomers are aliphatic or aromatic hydroxycarboxylic acids other than lactic acid. These can be linear or branched. Lactones are also suitable as comonomers. Examples of suitable hydroxycarboxylic acids or lactones are those of the general formulas I or II:

HO E— C (O) ^• ] _α HC (O) G ″ - nO— 1, 1

(I) (II)

where the variables have the following meaning independently:

G, G ': are identical or different and mean phenylene,

- (CHa) s-. -CfR ^ H, -C (R ² ) HCH ₂ ,

R ¹ , R ² : are identical or different and are methyl,

Ethyl,

q: an integer from 1 to 5,

r: an integer from 1 to 4,

s: an integer from 1 to 5.

Examples of suitable hydroxycarboxylic acids, hydroxypropionic acid or 4-hydroxycyclohexylcarboxylic acid. Ss-Propiolactone, ß-valerolactone, γ-valerolactone or δ-valerolactone are mentioned as examples of lactones which come into consideration.

Aliphatic hydroxycarboxylic acids having 2 to 10 carbon atoms are preferred, including in particular glycolic acid, its cyclic derivative glycolide (1,4-dioxane-2, 5-dione), 3-hydroxybutyric acid, 3-hydroxyvaleric acid or 6-hydroxyhexanoic acid. The preferred lactones include propiolactone and δ-valerolactone.

The polylactides (a) may also contain building blocks which are derived from diols.

Generally, branched or linear alkanediols having 2 to 12 carbon atoms, preferably 4 to 6 carbon atoms, or cycloalkanediols having 5 to 10 carbon atoms, or polyether diols, i.e. Dihydroxy compounds containing ether groups are used.

Examples of suitable alkanediols are ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 2,4-dimethyl-2-ethylhexane 1,3-diol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 2, 2,4-trimethyl-l, 6-hexanediol, in particular ethylene glycol, 1,3-propanediol, 1,4-butanediol and 2,2-dimethyl-1,3-propanediol (neopentyl glycol); Cyclopentanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol or 2,2,4,4-tetramethyl-l, 3-cyclobutanediol. Mixtures of different alkanediols can also be used.

Examples of polyether diols are diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetrahydrofuran, in particular diethylene glycol, triethylene glycol, polyethylene glycol, or mixtures thereof, or compounds which have a different number of ether units, for example polyethylene glycol which contains propylene units and for example, by polymerization according to known methods of first ethylene oxide and then propylene oxide. The molecular weight (M _n ) of the polyethylene glycols which can be used is generally about 250 to about 8000, preferably about 600 to about 3000 g / mol. Mixtures of different polyether diols can also be used. In addition, the polylactides can contain isocyanates as building blocks. Among them, aliphatic isocyanates, especially hexamethylene diisocyanate, are preferred.

Mixtures of diols and / or isocyanates and / or hydroxycarboxylic acids and / or lactones can also be used.

It is also possible that the polylactides (a) are still composed of epoxides or mixtures of difunctional, trifunctional and / or tetrafunctional epoxides. Bisphenol A diglycidyl ether is an example of a suitable difunctional epoxide. As trifunctional epoxides are 1, 3, 5 -Tris -oxiranyl - methyl- [1,3,5] trιazman-2, 4,6-trioxane, 2,4,6 -Tris -oxiranyl [1,3,5] trioxane , Benzene-1,3,5-tricarboxylic acid tris-oxiranyl - methyl ester or 1,1,1-trιs (hydroxymethyl) ethane-tris (glycidyl ether) 1,1,1-tris (hydroxymethyl) propane-ris (glycidyl ether ) m consideration. 4,4 'methylenebis [N, N-bis (2,3 epoxypropoyl) anilm] or pentaerythritol tetraglycidyl ether can be used as a four-functional epoxide

Polylactides (a) containing building blocks derived from epoxides are known and can e.g. be produced by methods known per se.

Multifunctional aliphatic or aromatic acids or their derivatives, preferably their anhydrides, can also be used as further building blocks in the polylactides (a). Trimellitic acid or pyrromellitic acid or their anhydrides are particularly preferably used.

In addition, the polylactides (a) can contain building blocks which are derived from trifunctional or polyfunctional alcohols. Among them, Glycerm or Neopentylglycenn are preferred.

Of course, different multifunctional components can be included. Likewise, the polylactides (a) may contain diols and / or isocyanates in combination with the multifunctional building blocks.

Preferred copolymers generally contain from 75 to

90% by weight of monomers derived from lactic acid or its derivatives or oligomers and from 10 to 25% by weight of comonomers. The production of polymers (a) which are derived from lactic acid is known per se or can be carried out by processes known per se. For example, lactic acid derivatives or the oligomers thereof can be directly polycondensed. It is also possible to convert lactide in a ring-opening polymerization to oligomers of lactic acid or to polylactide. Block copolymers can then be obtained, for example, by reacting polylactide with oligomers or polymers of the hydroxycarboxylic acids or the lactones or mixtures thereof. For example, block copolymers of polyglycolic acid and polylactide can be produced in this way.

According to the method described in EP-A-769 512, e.g. a lactic acid halide is first produced by reacting lactic acid with an imidazolinium halide and this is condensed to the polymer in the presence of a base with the elimination of hydrogen halide. Examples of suitable imidazolinium salts are 2-chloro-1,3-dimethylimidazolinium chloride or 2-chloro-1,3-dibutyllimidazolinium chloride. Both inorganic and organic bases and basic ion exchange resins can be used as the base. The acid chlorides are generally produced at temperatures below 160 ° C and the polycondensation generally at temperatures below 180 ° C. In principle, this process can also be applied to lactic acid oligomers or the reaction with the other hydroxycarboxylic acids as comonomers. Mixtures of the monomers can be reacted with one another or a gradual polymerization of the different monomers can take place.

Another process for the preparation of copolymers from lactic acid and other hydroxycarboxylic acids can be found, for example, in EP-A-603 889. In this process, the acids are polycondensed in the presence of a solvent and a catalyst at temperatures in the range from 50 to 250 ° C. and with the water of reaction formed being removed.

In general, the polylactides have molecular weights (number average Mw) in the range from 100,000 to 300,000 g / mol.

Molding compositions based on aliphatic polyester (b) which are not derived from lactic acid can also be used according to the invention.

These aliphatic polyesters (b) include homopolymers of the aliphatic hydroxycarboxylic acids already mentioned under a as comonomers (aliphatic polyesters b1) or lactones (aliphatic polyesters b2) and copolymers of different hydroxycarboxylic acids or lactones or mixtures thereof (aliphatic polyesters b3). These aliphatic polyesters (b) can also contain diols and / or isocyanates as building blocks, where primarily those mentioned under a. Furthermore, the aliphatic polyesters (b) can also contain building blocks which are derived from trifunctional or multifunctional compounds such as the epoxides, acids or triols mentioned under a. The latter components can of course also be contained in the aliphatic polyesters (b) together with the diols and / or isocyanates.

Methods for producing these homopolymers (bl) are known (see e.g. EP-A 603 889). They generally have molecular weights (number average) in the range from 10,000 to 100,000 g / mol.

Polycaprolactone is one of the particularly preferred aliphatic polyesters b2.

Poly-3-hydroxybutanoic acid esters and copolymers of 3-hydroxybutanoic acid or their mixtures with the 4-hydroxybutanoic acid and 3-hydroxyvalane acid, in particular a weight fraction of up to 30, preferably up to 20% by weight of the latter acid, are particularly preferred aliphatic polyester (b3). Suitable polymers of this type also include those with an R-stereospecific configuration, as are known from WO 96/09402. Polyhydroxybutanoic acid esters or their copolymers can be produced microbiologically. Methods for the production from various bacteria and fungi are e.g. Chem Tech. Lab. 39, 1112-1124 (1991), a method for producing sterospecific polymers is known from WO 96/09402.

In addition, block copolymers from the named

Hydroxycarboxylic acids or lactones, their mixtures, oligomers or polymers are used.

Such aliphatic polyesters (b) generally have molecular weights (number average) in the range from 10,000 to

100,000 g / mol. Methods for their preparation are known to the person skilled in the art.

Further aliphatic polyesters (b) are those which consist of aliphatic or cycloaliphatic dicarboxylic acids or their

Mixtures and aliphatic or cycloaliphatic diols or mixtures thereof are constructed (aliphatic polyester b4). According to the invention, both statistical and block copolymers can be used. The aliphatic dicarboxylic acids suitable according to the invention generally have 2 to 10 carbon atoms, preferably 4 to 6 carbon atoms. They can be both linear and branched. The cycloaliphatic dicarboxylic acids which can be used in the context of the present invention are generally those having 7 to 10 carbon atoms and in particular those having 8 carbon atoms. In principle, however, dicarboxylic acids with a larger number of carbon atoms, for example with up to 30 carbon atoms, can also be used.

Examples include: malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, acelamic acid, sebacic acid, fumaric acid, 2, 2-dimethylglutaric acid, subermic acid, 1,3-cyclopentandecarboxylic acid, 1, 4-cyclohexanedecarboxylic acid, 1, 4-cyclohexanedocarboxylic acid hexanedicarboxylic acid, diglycolic acid, itaconic acid, maleic acid and 2, 5-norbornane carboxylic acid, among which maleic acid is preferred

As ester-forming derivatives of the abovementioned aliphatic or cycloaliphatic dicarboxylic acids, which can also be used, are in particular the di-Cχ- to Cg-alkyl esters, such as dimethyl, diethyl, di n propyl, di-isopropyl, di-n-butyl, di - Iso-butyl, di-butyl, di-n-pentyl, di-iso-pentyl or di-n-hexyl esters are mentioned. Anhydrides of the dicarboxylic acids can also be used.

The dicarboxylic acids or their ester-forming derivatives can be used individually or as a mixture of two or more thereof.

Examples of the aliphatic polyesters (b4) under consideration are aliphatic copolyesters as described in WO 94/14870, in particular aliphatic copolyesters from succinic acid, its diesters or their mixtures with other aliphatic acids or diesters such as glutaric acid and butanediol or mixtures thereof Diol with ethylene glycol, propanediol or hexanediol or mixtures thereof.

Aliphatic polyesters of this type generally have molecular weights (number average) in the range from 10,000 to 100,000 g / mol.

Likewise, the aliphatic polyesters (b4) can be random or block copolyesters which contain further monomers. The proportion of the other monomers is usually up to

10% by weight. Preferred comonomers are hydroxcarboxylic acids or lactones or mixtures thereof. Suitable hydroxcarboxylic acids or Lactones were listed under a. Such aliphatic polyesters are generally characterized by proportions of hydroxycarboxylic acid and / or lactone units in the range from 0 to 10% by weight and are known per se.

Mixtures of two or more comonomers and / or further building blocks, such as epoxides or highly functional aliphatic or aromatic acids or highly functional alcohols as described under a, can of course also be used to prepare the aliphatic polyesters (b4).

According to the invention, the molding composition can also consist of partially aromatic copolyesters (c). A number of molding compositions of partially aromatic copolyesters which can be used according to the invention are known, for example, from US Pat. No. 5,446,079, to which reference is expressly made. Other copolyesters (c) can be found in WO 96/15173, 15174, 15175, 15176, 25446 and 25448, to which reference is expressly made.

The preferred partially aromatic copolyesters (c) include copolyesters which act as monomeric building blocks

θ) a mixture of

cχι) 20 to 95 mol%, preferably 30 to 70, in particular 50 to 60 mol% of at least one aliphatic or cycloaliphatic dicarboxylic acid or its ester-forming derivative and

Cχ) 5 to 80 mol%, preferably 30 to 70, in particular 40 to 50 mol% of at least one aromatic dicarboxylic acid or its ester-forming derivative and

c ₂ ) at least one dihydroxy compound

and if desired

c ₃ ) a compound which contains two functional groups which can react with the acid, amino or hydroxy end groups of the polyester, obtainable from components ci and c ₂

contain.

The aliphatic dicarboxylic acids or their derivatives (cu) can be those listed under (b4), of which adipic acid or sebacic acid or their respective ester-forming derivatives are particularly preferred. These can be used alone or it Mixtures of adipic and sebacic acid or the respective derivatives can be used. Adipic acid or its ester-forming derivatives allems are particularly preferably used.

Aromatic dicarboxylic acids (cι ₂ ) are generally those with 8 to 12 carbon atoms and preferably those with 8 carbon atoms. Examples include terephthalic acid, isophthalic acid, 2,6-naphthoic acid and 1,5-naphthoic acid and ester-forming derivatives thereof. The D 1 -C ₆ -alkyl esters in particular, for example diethyl, diethyl, di-n-propyl,

Di-iso-propyl, di-n-butyl, di-isobutyl, di-t-butyl, di-n-pentyl, di-iso-pentyl or di-n-hexyl esters may be mentioned. The anhydrides of dicarboxylic acids (cι) are also suitable ester-forming derivatives.

In principle, however, aromatic dicarboxylic acids (cχ) with a larger number of carbon atoms, for example up to 20 carbon atoms, can be used.

The aromatic dicarboxylic acids or their ester-forming derivatives (cι) can be used individually or as a mixture of two or more thereof. Terephthalic acid or its ester-forming derivatives such as dimethyl erephthalate are particularly preferably used.

According to the invention, at least one is used as component (c)

Dihydroxy compound or mixtures of different dihydroxy compounds used. In principle, all diols can be used which can form esters with the dicarboxylic acids (c _{1: L} ) or (c ₁₂ ).

In general, however, branched or linear alkane diols and / or polyether diols are used as component (c), as already indicated under (a). According to a preferred embodiment, 1,4-butanediol is used.

The molar ratio of (ci) to (c) is generally in the range from 0.4: 1 to 2.5: 1, preferably in the range from 0.5: 1 to 1.5: 1, more preferably in the range from 0 , 5: 1 to 1.2: 1 and in particular in the range from 0.8: 1 to 1.1: 1.

According to the invention, these partially aromatic copolyesters can, if desired, also be composed of compounds (c ₃ ) which contain two functional groups which are linked to the acid or hydroxy end groups of the polyester which is obtainable from components (θχ) and (c), can react. The preferred compounds c include aliphatic isocyanates such as hexamethylene diisocyanate. The compounds (c) are usually in amounts of 0 to 1.5 mol, based on the sum of components (ci) and (c) contained in the polyesters.

The molar ratio of (ci) and (c ₂ ) in the isolated partially aromatic polyesters 5 is preferably approximately 0.4: 1 to 1: 1 after removal of the desired amount of excess component (c).

The partially aromatic copolyesters 10 can contain epoxides or multifunctional acids or their derivatives or multifunctional alcohols or mixtures of the compounds mentioned as further building blocks. Here, e.g. which are already used under (a) and (b4).

15 Particularly preferred partially aromatic copolyesters (c) are branched and, if at all, only to a minor extent crosslinked. Their intrinsic viscosities are generally in the range from 1.2 to 3.3, preferably from 2.1 to 2.9 dl / g, determined on 0.5% by weight solutions in phenol / tetrachloroethane (% by weight -

20 nis 60/40 at 25 ° C). This corresponds to molecular weights (weight average Mw) of approximately 80,000 to approximately 180,000 g / mol, or approximately 110,000 to approximately 150,000 g / mol. The molecular weights are determined by means of gel permeation chromatography (narrowly distributed polystyrene standards and tetrahydrofuran as solvent). your

The polydispersity index (PDI = Mn / Mw) is in the range from 2 to 7, preferably 3 to 5.

In general, the molding compositions which can be used according to the invention contain from 80 to 100, preferably from 85 to 95, in particular from 30 90 to 93% by weight, based on the total weight of the molding compositions, of at least one biodegradable polylactide or polyester or mixtures thereof.

In addition, the molding compositions can contain from 0 to 20, preferably from 35 to 15, in particular from 7 to 10,% by weight of further polymers. These can be biodegradable.

In addition to the polymer components, the molding compositions for producing the films can contain further additives and processing aids 40. Their proportion is generally up to 10% by weight, preferably up to 5% by weight, based on the total weight of the polymer component.

45 Typical additives are, for example, stabilizers and oxidation retardants, agents against heat decomposition and decomposition by ultraviolet light, lubricants and mold release agents, dyes, pigments and plasticizers.

Lubricants and mold release agents which can generally be added up to 1% by weight of the thermoplastic composition are, for example, long-chain fatty acids or their derivatives such as stearic acid, stearyl alcohol, stearic acid alkyl esters and -a ide and esters of pentaerythritol with long-chain fatty acids. Erucamide, palmitamide, stearylamide or ethylene-bis-stearylamide are particularly preferred. The salts of the first or second main group of the periodic table of the acids mentioned, such as sodium stearate or calcium stearate, are also suitable as lubricants. Also preferred are amide waxes from C 1 to C 1 monoamines or C to C diamines with a C ₁₄ to C ₈ monocarboxylic acid. Preferred compounds are ethylene distearylamide or ethylene diol amide, which are contained in amounts of 300 to 3000, preferably 1000 to 2000 ppm, based on the polymer component. Si0 ₂ , Na AlSi0 ₃ and CaC0 ₃ particles may be mentioned as antiblocking agents.

Lubricants and / or antiblocking agents are preferably applied by external coating of the granules (so-called external lubrication), the lubricant being applied to the granules e.g. is drummed up.

Inorganic pigments such as titanium dioxide, ultramarine blue, iron oxide and carbon black, furthermore organic pigments such as phthalocyanines, quinacridones, perylenes and dyes such as nigrosine and anthraquinones can be added as colorants.

When pigment or antiblocking agent is added, a batch (concentrate) of polymer and additives is preferably prepared, 5 to 50, preferably 15 to 35% by weight of the additive, e.g. can be incorporated into a polyamide matrix using conventional extruders. This concentrate is then usually mixed as a physical mixture with further polymer granules and the granulate mixture is processed into a film.

According to one embodiment, the foils, in particular colored foils, can also have a multilayer structure. The pigmentation is preferably carried out in the intermediate layer. In addition to a colored pigment, the outer layer can be mixed with 0.01 to 1, preferably 0.1 to 0.3% by weight of a white pigment, for example Ti0 ₂ , to achieve a matt film surface. The molding compositions can contain up to 30% by weight, based on the total weight of the molding compositions, of fillers. For example, native or dried starch or cellulose fibers can be used as filler. However, the preferred molding compositions generally contain no fillers or reinforcing materials. In addition, particularly preferred molding compositions generally also contain no colorants.

The molding compositions can be produced by mixing the components in a manner known per se. The order in which the individual components are added can vary. For example, all components are added together. Alternatively, individual components can be premixed. As a rule, the molding compositions are produced in conventional mixing devices such as Brabender mills or Banbury mixers, preferably in an extruder. The molding compounds can then be discharged and granulated or processed into films immediately after discharge.

The films available from the molding compositions generally consist of only one layer. In particular, the films are tubular films. In general, the films have good mechanical properties which can be further improved by orienting the films, preferably stretching them biaxially.

For the production of biaxially oriented films, the primary films are in the usual way after solidification by 1.1 to 7.0 times, preferably at least 1.5 times, particularly preferably at least 2 times, especially 2 Stretched 5 to 3.5 times lengthways and crossways. This can be achieved, for example, by guiding the foils over rollers at different speeds. In the case of biaxially oriented films, the film can be stretched in width at the same time or in two steps using laterally attached devices, so-called clip chains. In the case of tubular films, the biaxial takes place

Usually stretching simultaneously during extrusion over the air enclosed in the bladder. The inflation ratio provides information about the orientation of the film in the circumferential direction under otherwise constant boundary conditions. The ratio of the take-off speeds of the last to the first pair of rollers indicates the degree of longitudinal orientation.

In the case of biaxially oriented tubular films, for example, a pressure of 1 to 3 bar is introduced into the tube, the pressure being dependent on the desired dimensions of expansion of the film. The stretching ratio lengthways / crossways is preferably 1: 2 to 1: 5, preferably 1: 2.5 to 1: 3.5.

In order to achieve good stretchability and reproducible caliber accuracy 5 (diameter accuracy) with biaxially oriented films, it is advantageous, however, after the molten discharge from the die of the extruder in a first stage to temperatures from 0 to 25 ° C, preferably 3 to Cool 10 ° C and then heat in a second stage to temperatures 0 from 30 to 95 ° C, preferably 50 to 80 ° C and then stretch.

After stretching the films, they can be heated with hot rollers or with hot air (approx. 75 to 150 ° C, preferably 100 to 120 ° C)

15 can be heat set. For this purpose, the foils are passed, for example, via rollers through a closed container with a tempered air stream or steam stream. The residence time is usually 1 to 20 s, preferably 2 to 5 s. Methods for stretching films are well known (see e.g.

20 US-A 3 456 044).

Preferred biaxially oriented films have a shrinkback value of from 2 to 40%, preferably from 5 to 15%, after the thermal fixation. The shrinkback is usually determined by boiling the film in boiling water for 25 minutes.

The total wall thickness is preferably 25 to 100, preferably 35 to 75 and in particular 40 to 60 μm, and the tube diameter (caliber) in the case of tubular films is 10 to 200, preferably 15 to 30 100, in particular 20 to 50 mm. The hose diameter is determined as the width of the flat hose.

The flat tubular films can then be printed and / or gathered using suitable systems.

35

According to the invention, the films are intended to be used for air-drying or smokable foods or for foods which are both air-dried and smoked. After the food has dried, the foils can

40 parts in air or after smoking as packaging material for these foods. It is just as good e.g. It is possible to air dry the food first and then to wrap it with the foil before smoking. However, the particular foodstuff is preferred before air drying or smoking

45 or packed in the film before both work steps. Suitable foods include meat products or raw sausage (so-called sausage meat). In addition, cheese (smoked cheese) or aspic can also be considered as food. Also worth mentioning are fish products, for example the smoked fish known in southern Europe, the dried fish eaten as snak food in Asia, especially Japan (eg Niboshi). Sausages, for example salami, cabanossi or chorisso, are particularly preferred.

In general, pickling salt is added to the food for preservation. Furthermore, a food smell flavor e.g. Liquid smoke must be added. Raw meat is filled from the cutter into the tubular film, which is then tied into sausages in the desired length or sealed with clips. The sausage can then be air-dried or additionally smoked or sprayed with a smoke aroma.

For drying or smoking, the food, in particular the raw sausage, is generally stored for 1 to 60 days at 10 to 50% relative atmospheric humidity and temperatures in the range from 10 to 60 ° C., the ambient air, if desired, using a sulfur fire with smoke can be enriched. Before drying or smoking, the food can be immersed in a liquid, preferably salt water, for a period of generally 1 to 14 days.

The foils are characterized by high gas permeability. Foods enclosed with it can therefore be easily air-dried and / or smoked. The foils are also inert to liquid smoke and withstand filling pressures well. Nevertheless, they can be cut well, but do not splice significantly. When drying, they keep their shape e.g. the straight elongated sausage shape and do not deform like a banana. In addition, they do not detach from the content when shrinking. Fine mold can develop on the film surface.

The films according to the invention are also suitable for the production of peelings for sausages without an outer skin (so-called Effenberger). For this purpose, the films are usually mixed with suitable lubricants, in particular oleic acid amide, erucic acid amide or waxes such as polyethylene waxes or beeswax. For this application, the films can also be used as a composite with parchment or paper sleeves. Examples

example 1

A partially aromatic copolyester based on terephthalic acid, adipic acid and 1,4-butanediol was used as the molding compound. This was extruded into a substantially unoriented tubular film using a 30 mm extruder (from Weber) at a melt temperature of 180 ° C., a throughput of 3.5 kg / h and a take-off speed of 12 m / min. The film was solidified by air cooling. The width of the double-flat film was 50 mm and the wall thickness was 50 μm (determined according to ISO 4591).

Comparative Example VI

The experiment was carried out as described in Example 1, but extrusion was carried out at a melt temperature of 250 ° C. and, instead of the copolyester, polybutylene terephthalate with a viscosity number (VZ) of 140 ml / g (determined in accordance with ISO 1628)

0.5 wt. -% solution in o-dichlorobenzene and phenol (50:50) at 25 ° C., Ultradur® B4500 from BASF AG. The width of the double-flat film was 50 mm and the wall thickness was 50 μm.

Comparative example V2

The experiment was carried out as described in Example 1, but instead of the copolyester polyamide 6 with a viscosity number (VZ) of 250 ml / g (determined in accordance with ISO 307 in a 0.5% strength by weight solution in 96% sulfuric acid at 25 ° C), Ultramid B4 from® BASF AG. The width of the double-flat film was 50 mm and the wall thickness was 50 μm.

Example 2

A partially aromatic copolyester based on terephthalic acid, adipic acid and 1,4-butanediol was used as the molding compound.

This was extruded into a substantially unoriented primary tube in a 45 mm extruder (from Plamex GmbH) at a melt temperature of 250 ° C., a throughput of 18 kg / h and a take-off speed (measured after the stretching step) of 60 m / min. The width of the double-layed primary hose was 10 mm and the wall thickness was 350 μm (determined according to ISO 4591). The primary tube was cooled with 6 ° C warm water and then tempered in a second water bath at 60 ° C for 1.4 s. The hose, filled with compressed air, was passed over rollers and stretched three times in the transverse direction (to a width of 30 mm) and 3.5 times in the longitudinal direction. In a further step, the tube was heat-set under shrinkage by 9% in the transverse direction (44 mm double flattened width) and by 12% in the longitudinal direction at 110 ° C. in a heat tunnel with a residence time of 4 s. After heat setting, the wall thickness was 41 μm.

Comparative Example V3

The test was carried out as described in Example 2. However, polyethylene terephthalate with a viscosity number (VZ) of 140 ml / g (determined according to ISO 1628 on 0.5% by weight solution in o-dichlorobenzene and phenol (50/50) at 25 ° C.) was used as the molding compound. It was extruded at a melt temperature of 275 ° C. The temperature of the second water bath was 90 ° C and that in the termixing step was 160 ° C. The width of the double-flat film was 45 mm and the wall thickness was 40 μm.

Comparative Example V4

The test was carried out as described in Example 2. However, polyamide 6 with a viscosity number (VZ) of 250 ml / g (determined in accordance with ISO 307 on a 0.5% by weight solution in 96% sulfuric acid at 25 ° C.) was Ultramid B4 from BASF AG used. It was extruded at a melt temperature of 250 ° C. The temperature of the second water bath was 70 ° C and that in the termixing step 150 ° C. The primary tube was 2.8 times in the transverse direction and in the longitudinal direction

Stretched 3.2 times. The width of the double-flat film was 40 mm and the wall thickness was 47 μm.

Application tests

The tensile strength σ [MPa] and the elongation at break ε [%] are determined according to ISO 527.

The light transmission D [%] of the films was measured according to ASTMD 1003.

The oxygen permeation was determined on the films after conditioning for 24 h at 100% moisture, 23 ° C. according to DIN 53 380.

The water permeation was measured according to DIN 53 122. The weight loss of the films was determined by filling approximately 250 g of a raw sausage mass into film sections of the same size. These were filled and tied as tightly as possible. They were kept hanging at 23 ° C and a humidity of 40%. Weight loss was measured after 7 and 30 days, respectively.

The results of the application tests are shown in the table.

table

Claims

claims

1. Use of molding compositions based on at least one biodegradable polylactide or polyester or their

Mixtures for the production of films for air-drying or smokable or air-drying and smokable foods.

2. Use according to claim 1, wherein the molding compositions are composed of at least one statistical partially aromatic copolyester or mixtures thereof with up to 20% by weight, based on the total weight of the molding compositions, of at least one further polymer.

3. Use according to claim 1 or 2, wherein the films are biaxially stretched.

4. Use according to claims 1 to 3, wherein the films are tubular films.

5. Use according to claims 1 to 4, wherein the foods are sausages.

6. Air-drying or smokable or air-drying and smokable food with a film made of a molding compound based on at least one biodegradable polyester.

7. A process for the production of films for air-drying or smokable or air-drying and smokable foods, characterized in that molding compositions based on at least one biodegradable polyester are extruded, biaxially stretched and heat-set.

8. The method according to claim 7, characterized in that one carries out the heat setting with residence times of 1 to 20 s and temperatures in the range of 75 to 150 ° C.

9. Biaxially stretched and heat-set tubular film made from a molding compound based on at least one biodegradable polyactide or polyester or a mixture thereof.