DE19619463A1 - Biodegradeable packaging material suitable for deep-drawing - Google Patents

Abstract

The material for deep drawing, esp. packaging material, has at least one non-woven layer of natural fibres, e.g. flax, hemp or similar, with a binder to allow reversible, non- destructive sliding of the fibres under pressure and heat. Also claimed is a deep-drawable material with a binder applied to the non-woven consisting of a cellulose acetate or starch film which combines with the fibres under pressure and heat. Also claimed are corresponding manufacturing processes incorporating alternatives of dry or wet forming of the material and dry or wet deep drawing of the article.

Description

The invention relates to a thermoformable material, in particular especially for packaging purposes, and a method of manufacture development of such a material.

For a long time, intensive efforts have been to known packaging materials, especially those made of Plastic or metal foils through products from so-called to replace renewable raw materials. With this measure should significantly reduce the burden on the waste balance compostable materials can be achieved.

Known natural packaging materials are based on dried and crushed leaves of certain plants, Rice or corn starch products or the like.  

Problems of such materials are limited regional availability as well as inadequate possibility speed of manufacturing processing without the Use of expensive special machines or complicated ver driving becomes necessary.

It is therefore an object of the invention to provide a packaging material and a method of making such a material specify, the material from natural, renewable Raw materials should exist and is therefore biodegradable and which still has deep-drawing properties, so that with already introduced or slightly changed Methods realized a corresponding shaping process can be.

The invention is intended to further applications by the poss the possibility of using known shaping processes are so that conventional packaging or Ver packaging materials can be replaced.

The object of the invention is achieved with a thermoformable packaging material according to the characteristics of the Claim 1 and by a method for manufacturing such a material as in claims 7, 9 and 11.

With the special packaging material according to the invention are quasi thermoplastic properties similar to this special plastics achieved, so that an excellent Given deep-drawing ability. The material obtained is wide Going grease and water vapor tight, food compatible as well as biodegradable and can e.g. B. analogous to the known Waste paper cycle can be reprocessed.

An essential basic idea of the invention is starting from a natural fiber fleece from flax or hemp or The like. To provide this with deep-drawing properties.  

This is done in that at least one non-woven layer is provided, which is a binder for reversible, non-destructive displacement of the fiber composite in one Has pressure-temperature process. The binder itself is also biodegradable and can be made from renewable Raw materials are produced.

With the help of the special binding agent, the Fiber of a wet or dry process Fleece possible during the deep-drawing or pressing process, without that the existing fiber composite is destroyed, so that from sufficient strength properties with shape retention are.

According to a first embodiment of the invention Binder made from a thin film of cellulose acetate or modified starch on the nonwoven layer brought or inserted between two layers of nonwoven is. During the actual deep-drawing process, it connects Layer of film with the fleece and forms a stable bond from which is inherently shape-preserving.

By varying the types of fleece with different ones Basis weight, types of weave, fiber lengths, variation of Binder, wherein films or film layers made of cellulose acetate and modified starch with different Grammage are used as well as by changes in Fiber composite, d. H. Transition to multiple layers or Sheets of nonwoven and film are the desired material properties with regard to strength and fat and Water vapor density adjustable.

According to a further embodiment of the invention, the Foil and nonwoven layer before the molding process for Receiving a pre-fixed composite thermally pretreated, see above that even more complicated forms are known by means of themselves Have deep drawing processes implemented.  

Another basic idea of the invention is that as Binder modified starch is used, which one Fiber mash is added to obtain a wet mat. The wet fiber fleece obtained in this way is in a still moist, partially dried state fed to a deep-drawing device and dried in a hot pressing step, the trains the desired fitting.

In the production of the deep-drawable wet fleece is on a technology that is largely based on the Paper production can be taken over, so that the Investi tion costs can be kept very low overall.

Following a third basic idea of the invention, one Filler mash containing modified starch, cellulose or cellulose acetate as a binder and vegetable filler fabrics, wood or waste paper, for coating the nonwoven used, alternatively the filler mash between two or several layers of nonwoven fabric are continuously introduced becomes.

According to the invention as a filler in the extraction of Flax or hemp-based shives are used.

With the application of the filler mash to the nonwoven this gets a moist constitution and becomes after a Partial drying or partial drainage, for example using a vacuum or fed to a deep-drawing tool by means of squeezing rollers.

During the deep-drawing process, the sliding action of the Binder-water mixture, i.e. H. through the properties of the Filler mash, the fiber composite stretched. With a the subsequent hot pressing process is followed by the residual drying Water evaporation carried out. This binds the binder with the fibers and fillers while maintaining the desired ten deep-drawing or press mold.  

All the briefly described embodiments of the Invention is common that through the reversible-plastic Properties of the material according to the invention a further ver processing of obtained shapes, if necessary by further Deep drawing or pressing steps, including embossing certain shapes or markings is possible. So can by adding moisture, e.g. B. by means of a spray device or a steam chamber the structure of the composite materials are loosened. With that in mind, it's in there a simple way of recycling the concerned, from the Products manufactured according to the invention guarantee accomplishes.

By adding dyes to the fiber or filler mash can meet high aesthetic standards Design of the packaging material according to the respective current application can be achieved.

According to a first procedural inventive idea the thermoformable packaging is manufactured materials or the like. In that first a natural fiber fleece is formed in a manner known per se, on which then a film layer of cellulose acetate or modified Starch is applied. Alternatively, multiple nature nonwoven layers be present, each between the Layers the film layer mentioned is provided.

Through a special thermal pretreatment that is obtained layer structure improves the handling of the Intermediate product, so that this easily in one heated or unheated deep-drawing tool for molding can be spent.

The thermal pretreatment of the layer structure can can be realized for example by hot rolling. To the plastic properties during a continuous Maintaining manufacturing and machining processes is one Heat chamber provided, the immediate output side of the  Heat chamber the material obtained in the still plastic state a deep-drawing or pressing tool is supplied.

A second procedural realization of the process for Production of thermoformable packaging material or the like consists in that again starting from a natural fiber fleece, which is made in a wet process from a fiber mix a binder is added to the fiber mash is that the desired plastic deformability of the secures dry fleece. After the natural fiber fleece was provided in the wet process, a partial drying performed. The partially dried nonwoven then gets into a deep drawing or pressing tool to form the desired one Shape.

The remaining drying of the fleece can then be done by hot pressing be realized, as a result of this procedure a shape-retaining composite structure between fleece and binder is given.

A third implementation variant of the invention Process for the production of deep-drawable Ver Packing material or the like is based on a special filling fabric mash layer, which is applied to the nonwoven fabric or is introduced between two nonwoven layers.

The filler mash consists of modified starch or Cellulose acetate and ground or crushed plants divide wood and / or waste paper. After the filler mash layer was applied or introduced, a Partial drying followed by a deep-drawing process molding step made. The remaining drying of the fleece hot pressing then serves to form the formerhal tendency composite structure similar to the above schil current procedure.  

Can advantageously be used as a filler for the filler mash the end of the production of flax or hemp Cockroaches can be used.

According to the invention for the production of the natural fiber fleece preferably to inferior in their use limited short fibers are used.

The particular advantages of the material according to the invention as well the manufacturing process for this is that little environmentally friendly substances through renewable, natural Raw materials can be replaced or replaced.

The necessary for the production of the thermoformable material manoeuvrable facilities and the associated investments can be kept low by z. B. from the paper technology Known technology is used. Chemical additives, which may be an incompatible component are not necessary. All in all, this shows fiction appropriate packaging material quasi thermoplastic property ten on, so that with deep drawing and / or pressing tools almost any shapes are possible. The invention Material represents a composite body made of natural nonwoven and special binder and is simple recyclable.

The invention will now be described with reference to the description of Embodiments and with the help of figures are explained in more detail.

Here show:

Figure 1 is a schematic representation of a plant for the manufacture of a thermoformable packaging material with a biodegradable thermoplastic film as a binder.

Figure 2 is a schematic representation of a Tiefziehvor device for molding objects from a thermoformable packaging material in the form of an endless belt made of a nonwoven film layer composite.

Fig. 3 is a schematic representation of the preparation of wet-laid web with a modified starch as a binder to obtain a deep-drawable material, particularly for packaging purposes, as well as the representation of the Tiefziehpreß- and drying process of the Naßvlieses; and

Fig. 4 is a schematic representation of the production of a thermoformable packaging material in the form of a fiber composite from two layers of nonwoven fabric with an intermediate layer of a filler mash.

With reference to FIG. 1, a first embodiment of the invention will first be described for the preparation of a thermoformable nonwoven fabric.

To make the fiber composite thermoformable, is a special binder in the form of a on the fleece provided film layer provided.

With the help of this binder is a mutual shift ben the fibers of the fleece possible without the actual Fiber composite is destroyed and the composite structure after a subsequent deep-drawing process is fixed so that a overall stable molded body is obtained. The used Binder is biodegradable and can regrow the raw materials are made available. As a binder according to an embodiment, cellulose acetate or modified starch used.

The binder is applied to the nonwoven by a thin layer of film immediately before the deep-drawing process from the aforementioned cellulose acetate or modified starch  is sprayed onto the fleece. This layer connects in the deep-drawing process with the fibers of the fleece while maintaining a stable network.

By varying the types of fleece with different ones Basis weight, type of weave and fiber lengths, a variation the binder, being cellulose acetate and modified starch with different basis weights are used, and by changes in the fiber composite, d. H. through commitment several nonwoven webs with one in between Foil layers are related to the respective application optimal properties of the material obtained adjustable.

Technically, in a first embodiment the supply of a non-thermally pretreated fiber ver bundle to a heated press tool with subsequent Deep drawing and fusing the composite in this tool respectively.

In a second embodiment, the fiber composite before being introduced into the press tool by hot rolling fused, the pressing tool also being heated.

A third embodiment is also based on one fused fiber composite by hot rolling, the Press tool itself is not heated and between the Hot rolling and the press tool feeder heat chamber is located, so that the aforementioned, plastic state of the Fiber composite up to the execution of the pressing and deep drawing ganges remains intact.

In the system shown in principle in FIG. 1, two nonwoven webs 1 and 2 are guided in a receiving device. Another sheet of biodegradable thermoplastic film 3 is arranged on the device side so that when the system shown in principle is operated continuously, the biodegradable thermoplastic film 3 is surrounded by the nonwoven webs 1 and 2 to form a sandwich structure. About a heating roller mill 4 , the nonwoven webs 1 and 2 are thermally compressed with the film 3 while maintaining thermoplastic properties of the material thus produced.

This prefabricated composite material passes into a heat chamber 5 and is exposed to a temperature effect within the chamber 5 by an infrared radiator 6 provided there, so that a desired plastic state until it emerges from the chamber and for the introduction of the composite strip into a deep-drawing tool ( Fig . 2) remains. Via deflection rollers 7 , vacuum-assisted if necessary, a supply loop 8 of the composite material 9 is generated, so that continuous operation of the system in connection with deep drawing is possible without the risk that the composite material 9 will have unacceptable loads in longitudinal and / or exposed to the cross direction.

In the deep-drawing process shown in principle in FIG. 2, a deep-drawing device with a heated punch 10 is assumed, which cooperates with a deep-drawing mold 11 , which is expediently cooled. The composite material is stamp 10 and mold 11 continuously fed.

After the positioning of the composite material 9, there is first a deep-drawing step followed by pressing, ie the plunger 10 sinks completely into the deep-drawing mold 11 .

A final process step consists of lifting the punch 10 and removing the molded composite material 12 . The molded body or the molded composite material 12 can then be separated from the running material web by means of a corresponding stamping step and the deep-drawing / pressing step begins again.

In a further embodiment according to FIG. 3, the thermoformable material is produced as a wet fleece with the supply of modified starch as a binder.

A particularly advantageous binder for production von Nassvlies is modified starch, which is the in itself Realized fiber mash is added in a known manner. The Starch increases with the formation of the actual fleece slightly known from paper technology modified device generated, d. H. here in the fiber composite installed.

The nonwoven fabric that is still moist becomes one immediately Thermoforming press device supplied, in the press tool during the deep-drawing process by sliding the particles within the starch / water mixture of the fiber composite is stretchable. Subsequently, a Hot pressing the remaining water evaporates, d. H. a Residual drying carried out and there is an intimate Ver bind the starch with the fibers of the fleece, creating a dimensionally stable fiber composite is produced.

By varying the binder in such a way that strength of different origins, e.g. B. potato, cereal or Corn starch of various degrees of modification is used comes as well as by varying the types of fleece different basis weight, type of weave and fiber length, can be combined with a vote of the Water content of the nonwoven produced and the optimization the temperature control in the press tool different form stable, d. H. Create tear-resistant materials.

A dye can be added to the fiber mix so that the products obtained correspond to the desired aesthetics table requirements can be designed as desired.

Fig. 3 shows a tub 20 , which is used to hold a mixture of fiber mash and binder. An agitator 22 is used to form the desired suspension 21 , ie the most uniform possible distribution of the solid constituents in the liquid dispersant. By means of a vacuum-assisted sieve and suction plate 23 , moisture is removed over a predetermined section and there is a accumulation of the nonwoven material along the sieve and suction plate 23 , soaked with binder. Via a perforated conveyor belt 24 and corresponding deflection rollers 25 , the wet fleece that forms is continuously moved out to a drainage section 26 .

This dewatering section 26 is used for the partial dehumidification of the nonwoven fabric in a continuous process. On the output side of the drainage section 26 , the nonwoven fabric 27 has a predetermined residual moisture. Further deflection rollers 28 are provided to form a compensating loop 29 , which achieves or aims the same effects as described with reference to FIG. 1. The nonwoven fabric 27 with residual moisture then reaches, as shown in the lower part of FIG. 3, a deep-drawing press and is first subjected to a deep-drawing process and then to a hot-pressing step.

As a result of the hot pressing step by means of the deep-drawing press, residual drying takes place, ie the expulsion or vaporization of the moisture still present in the nonwoven 27 . This creates a molded part 31 , which can be detached from the composite by appropriate punching or cutting tools 32 .

As from the embodiment described above can be seen, the manufacturing process of wet nonwoven with modified starch as a binder on a continuous basis Lichen operation aligned, so that high productivity can be achieved at low cost.

It should be noted at this point that with all execution examples from short fibers in a particularly advantageous manner Fiber plants such as flax, hemp or the like can be used can, which is otherwise an inferior component represent and can be refined only with great effort.  

According to a third exemplary embodiment and with reference to FIG. 4, a composite material with deep-drawing properties is obtained in that a mixture of a filler, binder and water, ie a filler mash 43, is applied or introduced between nonwoven webs 41 and 42 .

The filler added to the mash consists of waste materials plant production, namely so-called shives or other parts of the plant, such as straw or C4 plants, caused by Drying or wet grinding converted into a usable size will.

There is also the option of processing as fillers Use wood waste or waste paper. As Binder becomes modified starch, cellulose or cellu Loseacetat used. The filler contained in the mash gives the nonwoven fabric special strength properties. Alternatively, a porous intermediate layer can be foamed are generated so that one in a particularly advantageous manner special packaging product excellent heat insulating Properties can be imparted.

A variation of the properties of the material, which according to the third embodiment is manufactured by Binder change, d. H. by using strength of different origins, such as potatoes, cereals, corn or Like. With different degrees of modification receive. In addition, by adjusting the water The thermoforming process in the fiber composite produced is optimized and the density and thus the strength and residual elasticity of the material obtained.

The filler mash 43 is continuously added to a funnel-shaped receptacle 44 , the nonwoven webs 41 and 42 being subjected to a continuous rolling process. The vessel 44 is located above an almost horizontal first drainage device 45 . This drainage device can be formed, for example, by a vacuum-loaded vessel, which is located below the nonwoven web 41 of the system described.

The first dewatering device 45 partially binds or solidifies the filler mash 43 on the surface of the nonwoven web 41 .

One or more pairs of squeezing rollers 46 form a second Ent dewatering stage, which is arranged on the output side of the first dewatering device 45 . The water or residues of the filler mash 43 which are released by means of the squeeze rollers 46 are fed into a collecting container 47 and, like the material recovered from the first dewatering device 45 , is reused. On the output side of the squeeze rollers 46 , an already pre-compressed fiber composite material is created, which can then be subjected to a deep drawing / pressing process in a manner as described in the above-described exemplary embodiments. As a result, moldings of very different dimensions are provided, which can be used in particular for packaging purposes.

It should be noted at this point that the use of the thermoformable material according to the aforementioned design examples not only limited to packaging purposes, but also this material, especially with a foamed one Intermediate layer, also as a building physiologically harmless Insulation material can be used.

All in all, provision is possible with the invention a composite material made of nonwoven fabric and binder, the is recyclable and compostable without any toxi waste products arise. Because of the possibility less high quality short fibers, also of animal origin, as well as so-called shives, which are used in flax or hemp processing, the overall cost can be reduced will. A composite structure consisting of several layers  fabric is not only extremely thermoformable, but also has excellent strength, in particular Tear properties.

Reference list

1 , 2 nonwoven fibrous web
3 slide
4 hot rolls
5 heating chamber
6 infrared heaters
7 pulleys
8 loop
9 composite material
10 heated deep-drawing stamps
11 deep-drawing mold
12 molded composite material
20 vat
21 mixture
22 agitator
23 Sieve / suction plate
24 conveyor belt
25 pulleys
26 drainage section
27 nonwoven fabric with the rest moist
28 rolls
29 compensation loop
30 deep drawing press
31 molded part
32 punching tool
41 , 42 nonwoven webs
43 filler mash
44 vessel
45 first drainage system
46 pairs of squeeze rollers as a second drainage device
47 collecting container

Claims (13)

1. Thermoformable material, in particular for packaging purposes, characterized by at least one layer of a natural fiber fleece made of flax, hemp or the like, wherein the at least one non-woven layer has a binder for reversible, non-destructive displacement of the fibers of the fiber composite in a pressure / temperature process. 2. Thermoformable material, characterized, that the binder is a film applied to the nonwoven layer of cellulose acetate or starch, which is in the  Pressure / temperature process with the nonwoven fibers keeping the shape connects. 3. thermoformable material according to claim 2, characterized, that the film layer of cellulose acetate or starch between two nonwoven layers is inserted or applied. 4. thermoformable material according to claim 2 or 3, characterized, that the structure of film and nonwoven layer before Forming thermally pretreated to obtain a composite is. 5. thermoformable material according to claim 1, characterized, that the binder is modified starch, which is one Fiber mash is added to obtain a wet mat. 6. thermoformable material according to claim 1, characterized, that the binder with ground fillers from plants, Wood and / or waste paper offset modified starch, Zellu is loose or cellulose acetate and a water thus obtained having filler mash applied to the nonwoven fabric or is inserted between two nonwoven layers. 7. Process for the production of thermoformable material, in particular for packaging purposes or the like, characterized by

• - Manufacture of natural fiber fleece;
• - Application of a film layer of cellulose acetate or modified starch on the natural fiber fleece layer or between two or more fleece layers;
• - thermal pretreatment of the layer structure;
• - Feed the pretreated, a composite layer structure in a heated or unheated deep drawing tool and molding.

8. The method according to claim 7, characterized, that the film layer between two nonwoven layers is introduced and the layer structure by means of hot rolling connected and then fed to a heat chamber, where almost immediately on the output side of the heat chamber plastic state a deep drawing / pressing step to form the Material is made. 9. Process for the production of thermoformable material, in particular for packaging purposes or the like., Characterized by

• - Production of natural fiber fleece in a wet process from a fiber mix with the addition of a binder for the plastic deformability of the fleece obtained;
• - Partial drying of the wet fleece and performing a deep-drawing step;
• - Residual drying of the fleece by hot pressing and forming a shape-retaining composite structure between the fleece and the binder.

10. The method according to claim 9, characterized, that modified starch is used as a binder. 11. Process for the production of thermoformable material, in particular for packaging purposes or the like, characterized by

• - Manufacture of natural fiber fleece;
• - Applying a filler mash layer to the nonwoven fabric or between nonwoven fabric layers, the filler mash consisting of modified starch or cellulose acetate and ground or shredded plant parts, wood and / or waste paper;
• - Partially drying the filler mash layer and performing a deep drawing step;
• - Residual drying of the fleece by hot pressing and forming a shape-retaining composite structure made of fleece, binder and filler.

12. The method according to claim 11, characterized, that as a filler in the production of flax or hemp resulting cockroaches is used. 13. The method according to claim 7, 9 or 11, characterized, that for the production of the natural fiber fleece preferably short fibers are used.