EP1249219B1 - Method and apparatus for manufacturing shaped bodies made of a biopolymer material - Google Patents

Abstract

A device for producing shaped bodies comprising at least one extrusion tool (1) for extruding an endless strip of material (15) and at least one form tool (2) used to process the material strip in order to form shaped bodies, especially capsules, in addition to a treatment station (3) which is used to impinge upon the material strip with heat. According to the invention, the material strip undergoes heat treatment at least once between the extrusion tool and the form tool in order to relieve stress.

Description

The invention relates to a method and an apparatus for producing shaped articles, in particular capsules, from a biopolymer material, in particular based on starch, according to the preamble of the independent claims 1 and 8.

Shaped bodies, in particular capsules, are today produced in continuous, automatable processes from endless material strips. The production of the shaped body shell and the filling of the same happens, in particular in one-piece capsules, in a single step. In this continuous process moldings are made, from which the capsule shells are assembled during and after filling by welding the outer edges of the moldings. The molding is done either by means of diverging and merging forms, e.g. in the Norton, Banner and Schering processes or by means of rotating forming rolls, as e.g. in the rotary-die process and in the accordogel process ("The Capsule" Fahrig / Hofer, Stuttgart, 1983, Lachmann / Liebermann / Kanig, "The Theory and Practice of Industrial Pharmacy", Third Edition, Philadelphia 1986). The filling takes place with the aid of metering pumps, which deliver a defined amount of active substance during the punching and welding of the molded parts to form a one-piece capsule shell. Welding, i. The seams are generally formed by pressure and heat.

The production process for moldings made of endless material straps makes a number of demands. One of the main requirements is the ability to use endless material belts To form a sufficient strength, which have a sufficient elongation at break and elasticity.

When gelatine is used as the base material, it is possible to produce material ribbons which fulfill all these conditions in an almost ideal manner.

Gelatin bands, in particular for soft gelatine capsules, can be prepared from a homogeneous mass of gelatin and water which is readily flowable at 40 ° C. to 80 ° C., which usually also contains additives such as glycerol and sorbitol. This is done at atmospheric pressure, where the mass of so-called spreaders is gravity poured or extruded through a slot on a cooled drum. The mass should solidify at about 15 ° C to 25 ° C (gel state). At lower extrusion temperatures, the water content must be increased to lower the melting point and viscosity, or extrusion under pressure must be performed. At extrusion temperatures above 100 ° C there is a risk that the mixture foams on exiting from the so-called spreader.

Out US 2,643,416 a device for the production of gelatin capsules is known. Before forming the capsules, the gelatin bands are treated in a heat bath, optimizing the temperature for capsule formation.

It has been found that the normally used unpressurized extrusion technique in gelatin tapes can not be transferred to other biopolymers, in particular base starch bases which contain starch and water and, if appropriate, additives such as glycerol or sorbitol, since the water-containing films also extend far at temperatures can be handled poorly under the extrusion temperature due to insufficient mechanical properties. It forms no gel state or the softening resp. Melting range is very large, so that at low temperatures, no strength is achieved, while at temperatures around 100 ° are still no sufficient flow properties. The production of corresponding endless belts of material from other biopolymers, especially from starch, is therefore difficult. The bands often do not have the properties required for further processing, in particular with regard to elongation at break and elasticity.

So shows EP 0 397 819 a process for producing thermoplastically processable starch, wherein the crystalline fraction in the starch is less than 5%. The process consists of mixing native starch with at least 10% by weight of an aggregate having a solubility parameter of at least 30.7 (MPa) ^1/2 . The mixture is transferred under heat in a temperature range between 120 ° C and 220 ° C in a melt, wherein an internal pressure of about 30 to 300 bar can be assumed. The water content of the starch is already reduced to less than 5% in the melt. Although this method provides a thermoplastic starch with good processability into molded articles which have sufficient strength, the elongation at break of the molded articles produced with this thermoplastic starch only reaches values between 40% and 55%. The elasticity of the starch films is thus too low for the production of one-piece capsule shells in continuous processes and leads to a tearing of the moldings in the production or to cracks in the finished capsule.

The starch film, which after the in EP 397 819 In addition, the disclosed method does not show the weldability or seam strength, which would meet the quality requirements of one-piece molded body shells, in particular capsule shells.

In the European patent application 99811071.2 , Published after the filing date of the present specification, a method is shown in which a thermoplastic composition based on starch under pressure and at temperatures of up to max. 160 ° C is extruded. Due to the rapid cooling of the extruded material strips due to the high temperature difference from the environment, which generally has a temperature of about 25 ° C, creating a so-called glass state, in which the long-chain polymer molecules are oriented. Although the tapes produced in this way have a sufficient breaking elongation of at least 100%. However, it has also been shown that these material ribbons have conserved stresses. These are caused in particular by the orientation of the polymer molecules during extrusion through the narrow gap of the nozzle and by the slight tensile stress between the die gap and the cooling roll. Various mechanical properties in the longitudinal and transverse directions of the extruded strips are the result. These anisotropic material properties of the bands can have a disadvantageous effect, in particular in downstream process steps. Deformations such as broadening or shortening of the bands or of the molded articles produced therefrom can be the result.

This is particularly disadvantageous when the material strips are incompletely heated during a short residence time during filling of the molded body and subsequent welding. Voltages are released uncontrollably. This can lead to asymmetric and / or deformed moldings. This is not tolerable for a routine production in which the moldings must have a dimensional accuracy of +/- 0.5 mm. In normal use and processing, in particular packaging, the molded body but the dimensional accuracy and aesthetics of the moldings is an extremely important and indispensable share.

It is therefore an object of the present invention to avoid the mentioned disadvantages of the prior art. In particular, a method and an apparatus for producing Formed bodies are made of endless belts based on biopolymers, which allow the production of reproducible moldings, especially when the base mass of the belts is extruded under pressure and / or at high temperatures.

According to the invention this object is achieved by a device according to claim 8 and by a method having the features in the independent patent claims 1 and 16.

It has been found that stresses resulting from the extrusion of the material strips at high pressure and / or high temperature can be reduced by subjecting the material strips to heat, in particular immediately before they are processed into shaped articles. The material band is relaxed by the application of heat. Preserved stresses are released before the processing of the material strips to moldings and thus can no longer influence the finished molded body.

According to the method according to the invention, the material band between the extrusion die and the die is subjected to at least one heat treatment to reduce stresses at a treatment station.

The temperature for the heat treatment must be selected so that the desired relaxation of the material bands results and the belt can be controlled without further stress build-up. This temperature depends on the process and the material. The desired relaxation in the context of the invention is achieved when the strip after the heat treatment no longer anisotropic but has isotropic mechanical properties, so that the mechanical properties of the strip in the longitudinal direction and in the transverse direction to a good approximation are identical. A definition for the term pair "anisotropic / isotropic" can be found in Römpp Chemie Lexikon, ed.: J. Falbe, M. Regitz, 9th edition, 1992, Georg Thieme Verlag, Stuttgart.

The tapes treated according to the invention thus also have a uniform elongation at break and a uniform elastic modulus E over the entire material strip. For the processing of material strips into moldings, in particular for the production of soft capsules in the rotary process, an elongation at break of at least 100% and a modulus of elasticity of less than or equal to 2 MPa in the temperature range from 40 ° C. to 80 ° C. are particularly advantageous.

The measurement of the elongation at break and the modulus of elasticity E can be carried out according to DIN standard 53455 or DIN EN ISO 527-1 to ISO 527-3. The elongation at break is measured according to this DIN standard at the corresponding encapsulation temperature.

According to the invention, at least one material strip is extruded and then subjected to heat at a treatment arrangement. Of course, according to the particular method chosen for producing the shaped bodies, it is also possible to extrude a plurality of material strips and then to subject them to a heat treatment.

For the purposes of the invention, the term molded body is to be understood as meaning any type of molded article which is suitable for receiving a filling material and sealingly enclosing it in the interior. This includes not only capsules but also other forms such. B. balls, pillows and figures. To date, there are numerous developments and deviations from the basic principle of the capsule.

Biopolymers materials in the context of the invention are all materials that can be extruded by suitable methods to endless material bands. According to the invention, this also includes physically and / or chemically modified biopolymers. Examples of biopolymers according to the invention are cellulose, in particular partially hydroxypropylated cellulose, alginates, carrageenan, galactomannans, glucomannans, casein and starch. Likewise, mixtures of different biopolymer materials within the meaning of the invention are conceivable.

Strength is particularly preferred. The term starch should be understood to mean native starches as well as physically and / or chemically modified starches. For the base materials used in the process according to the invention, all starches, irrespective of the plant from which they are obtained, are suitable. In a preferred embodiment, it is starch whose amylopectin content is more than 50% based on the total weight of the anhydrous starch. Potato starch is particularly suitable.

However, in the process of the invention, in the broadest sense, all polyglucans, i. 1.4 and / or 1.6 poly-α-D-glucase and / or mixtures between them are suitable.

The production of endless material tapes based on starch as well as process parameters and material properties are in the Late Publishing (30.5.2001) European patent application 99811071.2 described in detail.

The process according to the invention can be an integral part of a known process for the production of moldings from endless bands of material, such as e.g. the Norton, Banner and Schering process or the methods by means of rotating forming rolls, e.g. realized in the Rotary-Die process and in the Accogel process ("The capsule" Fahrig / Hofer, editors, Stuttgart, 1983, Lachmann / Liebermann / Kanig, "The Theory and Practice of Industrial Pharmacy", Third Edition, Philadelphia 1986).

Particularly preferably, at least two material strips are processed according to the Rotary-Die principle into moldings, wherein each of the material strips is subjected to at least one heat treatment between extrusion and processing into moldings at a treatment station. The Rotary Die process with rotating forming rolls has been known and used for many years and today represents one of the most widespread encapsulation processes for the production of pharmaceutical, dietetic and technical shaped bodies.

In a particularly preferred embodiment, the endless material bands are applied to both sides with heat. The heat treatment can be effected by radiation, in particular by IR radiation. Likewise, the use of ultrasound, microwave and other suitable radiation sources for heating is conceivable.

It is also conceivable to carry out the heat treatment by convection heat. The material bands are passed to a radiator or through a preheated cavity of a treatment arrangement, in particular passed through a heating tunnel.

In a further variant of the method according to the invention, the material strips are passed through a heatable bath, in particular an oil bath. Thus, in addition to the desired relaxation, a lubrication of the material strips can be achieved, which can be particularly advantageous for further process steps. The bath temperature is preferably maintained in a range between 40 ° C and 80 ° C.

It is particularly advantageous if the tension of the material strips is kept constant with a compensating means, in particular with the aid of at least one dancer roller. Overlengths can z. B. by unequal or fluctuating rotational speeds of responsible for the movement of the endless material belts means of transportation, especially roles, arise. By maintaining a constant longitudinal tension is achieved in particular that negative influences on the relaxed by the inventive method by applying heat relaxed material bands.

Another object of the present invention is an apparatus for producing moldings, in particular capsules, from a biopolymer material, in particular based on starch, with at least one extrusion tool for extruding an endless material strip and at least one molding tool for processing the material strip under the influence of a filling material to moldings wherein between the extrusion die and the mold at least one treatment station for applying the material strip is arranged with heat.

In one embodiment, the treatment arrangement has at least one radiation source, in particular an infrared radiation source. Also conceivable are combinations of different radiation sources.

It is also conceivable that the treatment station has at least one heating element, wherein the material strips are acted upon by convection heat.

In a further variant (claim 16), the device according to the invention comprises a heatable bath, in particular an oil bath. Thus, in addition to the desired relaxation and lubrication of the material bands can be achieved. In the oil bath, an oil is used, which is harmless from a pharmaceutical and toxicological point of view in the subsequent application of the moldings. Such oils are known and listed in the relevant legislation. Optionally, the oil bath can be mixed with other additives that the properties of the material bands, such. B. affect elasticity or elongation at break positive.

The use of a heatable oil bath is particularly suitable for relaxing material strips, in particular based on starch.

It is particularly advantageous if the device has at least one stripping device for stripping off liquid from the surface of the material strips between the oil bath and the molding tool. The stripping device can be designed such that the film thickness of the film remaining on the surface of the material strips can be predetermined.

In a further preferred embodiment, the device has at least one compensating means, in particular a dancer roller, for maintaining a uniform longitudinal tension of the material bands. Unlength of the bands z. B. arise by non-synchronous means of transport, can be compensated. In particular, so can the tension so be kept as low as possible, particularly advantageous below 0.5 Mpa.

In a particularly preferred embodiment, the mold of the apparatus is a rotary die apparatus having two forming rolls and a filling wedge.

It is advantageous for the process control if at least one respective extrusion tool is arranged on both sides of the molding tool in such a way that the material strip is introduced into the molding tool on a conveying plane without lateral deflection. By omitting lateral deflections, as they occur in particular in the processing of gelatin ribbons partially, it is prevented that additional strains reach the ribbons, which can lead to anisotropic material properties.

For the reasons mentioned, it is particularly advantageous if the device has at least one adjustable positioning arrangement on which the extrusion tool and the molding tool can be adjusted relative to one another. As a result, a rigid but adjustable arrangement of extrusion and molding tool is achieved relative to each other. In particular, this makes it possible to prevent the transfer of stresses to the material strips by unevenly aligned extrusion and molding tools. The positioning could z. B. have a displaceable on a rail machine frame for the extrusion tool.

Figur 1

eine schematische Darstellung einer erfindungsgemässen Vorrichtung zum Herstellen von Formkörpern aus endlosen Materialbändern im Rotary-Die-Verfahren,

Figur 2

eine schematische Darstellung einer erfindungsgemässen Vorrichtung zum Herstellen von Formkörpern aus endlosen Materialbändern im Norton-Prozess,

Figur 3

eine schematische Darstellung eines alternativen Ausführungsbeispiels mit Flüssigkeitsbad,

Figur 4

ein Diagramm zur Bruchdehnung von Stärkebändern vor und nach Behandlung mit dem erfindungsgemässen Verfahren, und

Figur 5

ein Diagramm zum Young'schen Elastizitätsmodul von Stärkebändern vor und nach Behandlung mit dem erfindungsgemässen Verfahren.

Embodiments of the invention are illustrated in the drawings and will be described in more detail below. Show it:

FIG. 1

a schematic representation of an inventive device for producing moldings from endless material bands in the rotary die process,

FIG. 2

a schematic representation of an inventive device for producing moldings from endless material bands in the Norton process,

FIG. 3

a schematic representation of an alternative embodiment with liquid bath,

FIG. 4

a diagram of the elongation at break of starch bands before and after treatment with the inventive method, and

FIG. 5

a diagram for Young's modulus of strength bands before and after treatment with the inventive method.

FIG. 1 shows a schematic representation of an inventive device for producing moldings from endless material bands in the rotary die process. The rotary die machine shown is used in a known manner for the processing of two endless material bands 15, 15 '. The material strips are extruded on each of an extrusion die 1, 1 'on the extruder 13 of slot dies 10 and withdrawn, each with a pair of rollers 7a, 7b and rolled to a constant thickness. The extruders 13 are continuously supplied with biopolymeric material 12, in particular with starch-based material. The extruded material strips 15 are fed to a mold 2 in a known manner. Shown is a substantially horizontal supply of material strips to the mold. Of course it is also conceivable the material bands in any to supply another angle to the mold. A vertical feed is particularly advantageous because it allows the load on the strip to be minimized by gravity.

The molding tool consists of two molding rolls 4a, 4b, wherein in the surfaces of the molding rolls 4a, 4b, the recesses required for the deformation of the molded body 11, in particular to capsules, are arranged. In the take-in gusset of the forming roller pair 4a, 4b, a filling wedge 5 is arranged, through which by means of a feed pump 6 from a Füllguttank 8 filling material 9 between the material belts 15, 15 'is introduced, wherein the material bands are deformed on the forming rollers 4a, 4b to capsules 11. In this case, it is possible to use liquid, pasty or, in certain cases, also powdery filling material 9 as filling material 9. Also conceivable is the encapsulation of pellets, tablets and much more.

According to the invention, the material strips 15 between the extrusion die 1 and the die 2 are subjected to heat at a treatment arrangement 3a, 3b. At the treatment arrangement 3a, the heat treatment in the embodiment shown by radiation z. However, it is also conceivable, as shown in the treatment arrangement 3b, the material bands 15, by convection heat, which is generated by radiator 24, in particular heating coils, and is discharged into a cavity 25 to heat. For locomotion and guidance of the material belts 15, 15 ', different guide and / or drive rollers 20 can be attached at corresponding locations.

FIG. 2 shows a schematic representation of an inventive device for producing moldings from endless material bands 15, 15 'in the Norton process. In this case, a material strip 15, 15 'are extruded from an extrusion die 1 and stripped with a pair of rollers 7 and rolled to the correct thickness. The material strip 15 'is guided in the region between the extrusion die 1 and the die 2 by a treatment station 3 for applying heat. In the embodiment shown, the heat is generated by the radiator 24 in a heating tunnel 26. The material strip 15 'can be guided via corresponding guide and / or drive rollers 20 to the mold 2.

It is particularly advantageous if, to compensate for excess lengths of the material bands 15, which can arise as a result of asynchronous movements of the rollers 20, they can be compensated with the aid of a dancer roller 21. So that the longitudinal tension of the material strip 15 are kept constant. The dancer roller 21 is accordingly movable on an axis perpendicular to the direction of movement of the material strip 15 by a distance D required for maintaining the longitudinal tension of the material strip 15. The dancer roller could also be used to measure the actual tension on a sensor 29. The sensor could therefore also be used for feed control or for emergency shutdown with inadmissible tension. It is particularly favorable if the tensile stress is kept below 0.5 MPa.

In the mold 2, the material band 15 in the Norton process in a known manner into shaped bodies 11, in particular capsules shaped. The capsules are formed between a preforming unit 17 and a capsule forming unit 16. In the upper parts of the units 16, 17, the capsules are preformed in a hose-like manner and filled via filling channels 18, which are supplied via a filling material feed 14. In the lower part of the capsule forming unit, the final encapsulation takes place. With each step or with each pushing apart and before squeezing the units 16, 17 moves the material band 15 just forward by one capsule length. In this case, the capsule is preformed lengthwise in the upper mold part, the preforming unit 17. It remains open at the top to allow the addition of the filling material 9.

FIG. 3 shows a schematic representation of an alternative embodiment of an inventive device. In this case, the material strip 15 extruded from an extrusion die 1 is supplied to an oil bath 27 via drive rollers 19, which are driven by a motor M. The oil bath 27 can be heated via a heating unit 28. By immersing the material strip 15 in the oil bath 27 on the one hand, the desired relaxation of the material strip 15 is achieved by the release of conserved stresses. At the same time, the material band 15 is lubricated by the oil bath 27. To overlength of the material strip 15, which z. Example, by different rotational speeds of the drive rollers 19 and the guide rollers 20 may arise, compensate, a dancer roller 21 is mounted in the region of the oil bath 27. The dancer roller 21 is otherwise the same design as in the embodiment according to FIG. 2 ,

In the exemplary embodiment shown, the material strip 15 is supplied on leaving the oil bath 27 of a stripping device 22. Excess oil can be removed from the surface of the material strip 15 on this stripping device 22. The stripping device 22 can be designed so that the film thickness of the oil film remaining on the surface of the material strips 15 can be set to a predeterminable value. Subsequently, the relaxed material band as already shown via guide rollers 20 is fed to a mold 2. In the exemplary embodiment shown, this is the molding tool 2 of a device operated in the rotary-die method. This method has a particularly favorable effect from that additional heat was introduced in the embodiment shown by the oil bath on the starch ribbon 15. As a result, the segment temperature in the region of the filling wedge 5 can be kept low. Consequently, it is also possible to encapsulate temperature-sensitive filling goods 9, in particular pharmaceutical active substances. By Bandebölung in the oil bath 27 can be dispensed with additional oiling, which are usually necessary due to the process. An oil bath 27 as a treatment station 3 for applying the material strip 15 with heat also has the advantage that other additives which positively affect the band properties such as viscosity, elasticity, elongation at break etc. can be added to the bath. Other liquids in place of oil such. As water, aqueous dispersions, etc. are conceivable.

FIG. 4 shows a diagram of the elongation at break of starch bands 15 before and after treatment with the inventive method. The elongation at break can be measured according to DIN standard 53455. Shown is in FIG. 4 the elongation at break in percent as a function of the temperature. Both the values for the elongation at break in the longitudinal direction and in the transverse direction of the starch strips 15 were determined. On the one hand, it can be seen that the elongations at break of at least 100% required for the forming process of the material strip 15 to form a shaped body 11 are achieved over the entire temperature range, both in the longitudinal direction and in the transverse direction. This is particularly important because a minimum elongation at break of 100% is necessary to encapsulate with existing Rotary-Die processes.

On the other hand shows FIG. 4 Clear that the elongation at break in the longitudinal and transverse directions before treatment with the inventive method are different. The starch band has anisotropic mechanical properties, which are due in particular to the resulting during the extrusion of the tapes conserved voltages. The processing of anisotropic ribbons can lead to bulky shaped bodies, in particular capsules, which increasingly also get caught in the forming rollers and hinder the production process.

In contrast, the starch ribbon 15 is relaxed after heat treatment and has isotropic properties. The measured breaking elongation of the material strips 15 is identical in the longitudinal direction and in the transverse direction to a good approximation. In the further processing of such material strips uniform moldings 11 are formed, which do not get caught in the forming rollers.

FIG. 5 shows a diagram of the elastic modulus of thickness bands 15 before and after treatment with the inventive method. The measurement of the modulus of elasticity E can be carried out according to DIN EN ISO 527-1 to ISO 527-3. As a result of the heat treatment, the modulus of elasticity, in particular in the range of 40 ° C. to 80 ° C., which is important for the processing of the material bands 15 into shaped bodies 11, is significantly reduced to 2 MPa and less. This is particularly important because a modulus of elasticity of at most 2 MPa is necessary to perform encapsulation with existing Rotary-Die methods. For the encapsulation necessarily the maximum pressure resp. the residence time of the material bands in Füllkeilbereich be chosen so that the material band can be "inflated" to a capsule. The filling wedge floats freely on the forming rollers and ensures the seal. The pressure can therefore not be increased arbitrarily, otherwise the filling material runs out between the material band and filling wedge.

Therefore, a deep modulus of elasticity of the material bands 15 plays a crucial role. The method according to the invention thus proves to be particularly advantageous with regard to the reduction of the modulus of elasticity achieved thereby. Overall, the material properties of the material strips are optimized for subsequent processing into shaped bodies.

Claims (16)

1. A method of producing shaped bodies, in particular capsules, from a biopolymeric material, in particular based on starch, in which at least one endless material strip (15) is extruded from an extrusion tool (13) and processed in a shaping tool (2) with the inclusion of a filling material at a plasticising temperature to form shaped bodies (11), characterised in that the material strip is subjected to at least one heat treatment at a treatment station (3) between the extrusion tool and the shaping tool to reduce stresses, wherein after the heat treatment the strip (15) no longer has anisotropic but isotropic mechanical properties so that the mechanical properties of the strip in the longitudinal direction and in the transverse direction are identical to a good approximation.
2. A method according to claim 1 characterised in that at least two material strips are processed to give shaped bodies using the rotary die principle, wherein both material strips are subjected to at least one heat treatment at a treatment station between extrusion and processing to give shaped bodies.
3. A method according to one of claims 1 and 2 characterised in that the heat treatment is effected by radiation from a radiation source, in particular by IR radiation.
4. A method according to one of claims 1 and 2 characterised in that the heat treatment is effected by convection heat.
5. A method according to one of claims 1 and 2 characterised in that the heat treatment is effected by immersing the material strip or strips in at least one heated bath, in particular an oil bath.
6. A method according to claim 5 characterised in that the bath temperature is maintained in a range of 40°C to 130°C.
7. A method according to one of claims 1 to 6 characterised in that the tensile stress in the material strip or strips is kept constant with a compensating means, in particular by means of a dancer roller (21).
8. Apparatus for producing shaped bodies, in particular capsules, from a biopolymeric material, in particular based on starch, comprising at least one extrusion tool (13) for extruding an endless material strip (15) and at least one shaping tool (12) for processing the material strip with the inclusion of a filling material to provide shaped bodies (11), wherein at least one treatment station (3) for applying heat to the material strip is arranged between the extrusion tool and the shaping tool, characterised in that the temperature for the heat treatment is so selected that the result is the desired stress relief of the material strips, which is reached when the strip after the heat treatment no longer has anisotropic but isotropic mechanical properties so that the mechanical properties of the strip in the longitudinal direction and in the transverse direction are identical to a good approximation, and the strip can be controlledly guided without further stress reduction.
9. Apparatus according to claim 8 characterised in that the treatment station for applying heat to the material strip includes a radiation source, in particular a radiation source emitting IR radiation.
10. Apparatus according to one of claims 8 and 9 characterised in that the treatment station for applying heat to the material strip has at least one heating body.
11. Apparatus according to one of claims 8 to 10 characterised in that the treatment station for applying heat to the material strip has a heatable bath, in particular an oil bath.
12. Apparatus according to claim 11 characterised in that disposed between the bath and the shaping tool is at least one stripping device for stripping off liquid, in particular for metering the coating with liquid.
13. Apparatus according to one of claims 8 to 12 characterised in that it has at least one compensating means, in particular a dancer roller, for maintaining a constant tensile stress on the material strip.
14. Apparatus in particular according to one of claims 8 to 13 characterised in that it has at least one adjustable positioning arrangement at which the extrusion tool and the shaping tool are adjustable relative to each other in respect of their relative position.
15. Apparatus according to one of claims 8 to 14 characterised in that the shaping tool (2) is a rotary die device having two shaping rollers and a filling wedge and at least one respective extrusion tool is arranged on each of the two sides of the shaping tool in such a way that the material strip is introduced into the shaping tool on a conveyor plane without lateral deflection.
16. Use of a heatable oil bath for stress relief of material strips of a biopolymeric material, in particular on the basis of starch, by heat treatment, wherein the strip (15) after the heat treatment no longer has anisotropic but isotropic mechanical properties so that the mechanical properties of the strip in the longitudinal direction and in the transverse direction are identical to a good approximation, in particular the strip (15) has a uniform elongation to fracture and a uniform modulus of elasticity.

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