WO2002006131A1

WO2002006131A1 - Shaped body coated with an elastic coating

Info

Publication number: WO2002006131A1
Application number: PCT/EP2001/008327
Authority: WO
Inventors: Anneliese Kesselring; Thomas KÖBLITZ
Original assignee: Apack AG für Biologische Verpackungen
Priority date: 2000-07-18
Filing date: 2001-07-18
Publication date: 2002-01-24
Also published as: AU2001272553A1; DE10034901A1

Abstract

The invention relates to a biodegradable shaped body on the basis of a starch-containing composite material, comprising at least two shaped elements that are interlinked via at least one connecting element. At least a part of said connecting element is provided with a substantially elastic coating. The invention further relates to a method for producing such a shaped body and to the use of a polymer dispersion.

Description

MOLDED BODY WITH ELASTIC COATING

The invention relates to a biodegradable molded body based on a starch-containing composite material with at least two molded elements connected to one another via at least one connecting element, and to a method for producing the same.

Food, drinks, food, plants, etc. are increasingly being offered in disposable or disposable packaging. This disposable or disposable packaging contributes significantly to the general volume of waste. In addition, the increasing use of such disposable or disposable packaging leads to the consumption of valuable raw materials such as petroleum, since these packages are regularly made of plastics such as polyethylene, polypropylene, polystyrene, etc.

For ecological reasons, attempts have therefore been made for some time to use renewable raw materials as raw materials for the production of such disposable packaging. Starch and biodegradable fibers are particularly suitable as renewable raw materials. For example, WO 96/23026 discloses moldings which consist of a starch-fiber composite. These moldings can also be biodegraded, for example by composting. The amount of waste to be disposed of via waste incineration plants or waste dumps can thus advantageously be reduced.

However, it is disadvantageous that in the case of shaped bodies based on starch, such as, for example, a hamburger box, the hinge consisting of starchy material easily breaks or tears when in use.

In the case of the molded body known from US Pat. No. 5,843,544, which is produced using a starch-containing mixture, it is proposed to provide the hinge with at least one notch or a fold in the hinge region in order to enable the hinge to be bent or bent along the notch or the fold.

The hinge according to US Pat. No. 5,843,544 has a reduced thickness due to the notch or the fold in this region of the hinge, by the thickness that occurs on the inside of the hinge during the bending or kinking Reduce tensions. Due to the notch-like incision, the hinge breaks or tears easily after repeated use.

According to the teaching of US 5,843,544, a polyol-containing plasticizer such as e.g. Glycerin, polyethylene glycol, propylene glycol or polypropylene glycol applied to the hinge area.

The hinge known from US 5,843,544 thus has several disadvantages. On the one hand, the construction of the hinge with one or more notches or one or more folds is complex. In particular, in the production of large quantities of such hinges, as occur, for example, in disposable containers such as starch-based hamburger boxes, it is difficult to produce such complexly designed hinges with a high throughput. According to the teaching of US Pat. No. 5,843,544, the baking mold in the area in which the hinge area is baked is preferably to be provided with a material with a lower heat capacity or with a poorer heat transfer capacity. Such baking tins are complex to manufacture and more prone to failure in continuous operation.

Furthermore, the application of a polyol-containing plasticizer cannot reliably prevent the hinge known from US Pat. No. 5,843,544 from being torn off or broken through after repeated use. It is therefore disadvantageous that, for example, when using a hamburger box, the receptacle is separated from the cover container, and thus it is no longer possible to reliably close the hamburger box. A further disadvantage is that when the hamburger box is used again, the cover container has to be held separately after opening or is easily lost.

It is therefore an object of the present invention to provide a biodegradable molded body which avoids the disadvantages known in the prior art and has a connecting element which does not break or tear even after repeated use.

The object on which the invention is based is achieved by providing a biodegradable molded body based on a starch-containing composite material with at least two molded elements connected to one another via at least one connecting element, at least a partial area of the connecting element being provided with a largely elastic coating. The object on which the invention is based is further achieved by a biodegradable molded body based on a starch-containing composite material with at least two molded elements connected to one another via at least one connecting element, at least a partial area of the connecting element being provided with a largely elastic coating, the connecting element being essentially free of polyols is.

The term biodegradable moldings is understood in particular to mean containers such as plates, cups, mugs, hamburger boxes, bowls, etc., which are provided, for example, with a cover such as a lid, the cover being connected to the container via at least one connecting element , These foils are made from a bakable mass which comprises starch, generally biodegradable fiber material, water and, if appropriate, additives such as protein, fillers, fluxes, dyes, etc.

The bakable mass is then baked into a shaped body in waffle molds known per se from wafer baking technology. The waffle shape has a shape corresponding to the molded body to be produced. The baking process takes about 10 to 100 seconds, preferably 60 seconds, at a temperature of 100 to 200 ° C, preferably at 150 ° C in the closed baking pan.

For the purposes of the invention, the term “starch” is understood to mean natural starch, chemically and / or physically modified starch, technically produced or genetically modified starch and mixtures thereof. Starch can be used as starch from corn, for example corn, waxy maize, wheat, barley, rye, oats, millet, rice, etc. or cassava or sorghum. Of course, the starch contained in legumes such as beans or peas or the starch contained in fruits such as chestnuts, acorns or bananas can also be used. The starch contained in roots or tubers can also be used.

Potato starch is particularly suitable. The potato starch advantageously contains one phosphorus ether group per 200 to 400 anhydroglucose units. The negatively charged phosphate groups are linked to the C6 position of the anhydroglucose unit. In the production of a bakable mass, the negatively charged phosphate groups, by means of mutual repulsion, detangle the individual potato amylopectin molecules. Due to the mutual repulsion of the negatively charged phosphate groups, the branches of the amylopectin molecules are largely unfolded or stretched out. This presence of esterified phosphate groups cause a high viscosity of potato starch-water mixtures.

In the context of the invention, the term “largely elastic coating” is understood to mean that the connecting element is provided with a coating that is compressible, stretchable and / or flexible, without tearing in the event of such compression, expansion and / or bending or the coating breaks.

For example, when a hamburger box is closed or opened, a connecting element arranged between the receptacle and cover container is bent by up to 180 °. When a hamburger box is closed, for example, the coating on the outside of the connection element when the hamburger box is closed is stretched and the coating on the inside is compressed. When the hamburger box is opened, the previously stretched area is compressed or the compressed area is stretched without the coating tearing.

The elasticity of the coating thus ensures, even after repeated use, that there is no separation of the shaped elements, for example the container and the cover, in the area of the connecting element.

The term "biodegradable fiber material" means in particular vegetable and animal fibers. For the purposes of the invention, cellulose-containing fibers are preferably used as vegetable fibers. Cellulose-containing fibers are fibers of any kind that contain cellulose or consist of cellulose. Animal fibers are so-called protein fibers such as wool, hair or silk.

Vegetable fibers that can be in different lengths and widths are particularly preferably used. In particular, plant fibers are used which have a length in the range from approximately 50 μm to approximately 3000 μm, preferably from approximately 100 μm to approximately 2000 μm, further preferably from approximately 150 μm to approximately 1500 μm, more preferably from approximately 200 μm to approximately 900 μm , most preferably from 300 μm to about 600 μm. The width of the plant fibers can be in a range from approximately 5 μm to approximately 100 μm, preferably from approximately 10 μm to approximately 60 μm, particularly preferably from approximately 15 μm to approximately 45 μm. The fibers are mainly made from wood, hemp or cotton. Such fibers can be produced in a manner known to the person skilled in the art. Furthermore, the biodegradable moldings can also contain protein on the basis of a composite formed from starch and biodegradable fiber material.

The term "protein" is understood to mean biopolymers based on amino acids. All so-called proteinogenic amino acids, i.e. the amino acids usually involved in protein building, as well as the so-called non-proteinogenic amino acids, which are usually not involved in protein building.

The term "protein" is also understood to mean peptides or polypeptides. The term "protein" in the context of the invention also includes naturally occurring protein, chemically modified protein, enzymatically modified protein, recombinant protein, protein hydrolyzates or mixtures thereof. The protein can be of vegetable or animal origin.

A bakable mass (baking mass, dough) comprising starch, biodegradable fiber material, protein and water surprisingly enables a shortening of the baking time of up to 35%, preferably up to 50%, compared to a bakeable mass without the use of protein. Furthermore, the use of protein enables the material requirement for the production of moldings to be reduced by up to 10% by weight to 20% by weight.

For example, proteins of animal origin such as actin, myoglobin, myosin, hemoglobin, collagen, elastin, immunoglobulins, keratins, fibroin, conchagens, ossein, albumins, caseins, FPC (fish protein concentrate) can be used as proteins. Casein, alkali caseinate, alkaline earth caseinate, casein hydrolyzate and mixtures thereof can also be used.

Prolamines such as e.g. Gliadin, Secalin, Hordein, Zein and corn and soy protein can be used. Soy protein in particular has proven to be extremely suitable. Soy protein is also extremely advantageously available commercially in large quantities at low cost.

Hydrophobic proteins are preferably used as proteins. Hydrophobic proteins are characterized by a high proportion of uncharged amino acids in the amino acid sequence. In particular, these proteins contain high proportions of glycine, alanine, valine, leucine, isoleucine, phenylalanine, tryptophan, proline and methionine, all of which give the protein a hydrophobic character. It is clear to the person skilled in the art that the proteins listed above are only an exemplary selection to illustrate the invention. Of course, other proteins or protein mixtures can also be used. An important criterion is that the price of the protein or protein mixture to be used is low in view of the very large numbers of moldings to be produced.

A molded body produced using a protein-containing bakable composition has a more closed surface. A more closed surface is particularly advantageous with regard to the thermal insulation ability of the molded body.

Furthermore, the bakable mass can additionally comprise additives. These additives make it possible to influence the properties of the biodegradable molded article produced. For example, hydrophobizing agents, whitening agents, food colors, flavorings etc. can be contained in the bakable mass as additives.

The term "additive" includes any compounds that are suitable for influencing the product properties of the molded body. These additives are preferably completely or essentially completely biodegradable. Preferred examples of these additives are hydrophobizing agents, whitening agents, colorants, food colors, flavorings, etc.

Hydrophobizing agents are constituents which impart hydrophobic properties to the molded article produced. Whiteners are compounds that are used to lighten the color of the moldings. For example, blue dyes are used as dyes, which are used, for example, for coloring fruit bowls or fruit carriers. The following blue dyes can be used, for example: natural colors or lacquered colors. Green dyes are also used, for example, which are used for coloring shells to hold plants. The following green dyes can be used, for example: natural colors or lacquered colors.

Food colors are dyes used to color the packaging of food. For the purposes of the invention, any aroma substance, in particular biodegradable aroma substance, which, for example, imparts a certain smell and / or taste to the molded article produced, can be used as the aroma substance. A particularly preferred example of hydrophobizing agents are fluoroalkyl polymers, the term "fluoroalkyl polymers" indicating that they are polymers which are composed of, in particular, repeating alkyl units, it being possible for one or more, possibly even all, hydrogen atoms to be replaced by fluorine atoms. For example, a hydrophobizing agent based on a perfluoroalkyl acrylate copolymer can be used.

The whitening agent can be a compound with at least one disulfone group. Such compounds are well known to those skilled in the relevant technical field. An example of such a disulfonic acid compound is 4,4'-bis (1,3,5-triazinylamino) stilbene-2,2'-disulfonic acid.

The term "bakable mass" is understood to mean a baking mass or a dough which is used in baking devices known from wafer baking technology, such as e.g. Baking tongs can be baked to form a shaped body. The bakeable mass is, for example, placed in a heated baking mold of such a known baking device, whereupon the bakeable mass is distributed in the baking mold and fills it completely. The bakeable mass present in the baking pan releases water or water vapor when exposed to heat, which emerges from the baking pan through the provided outlet channels. During this process, the bakeable mass is solidified, providing the desired shaped body.

Preferably the bakable mass contains from about 3% to about 15%, preferably from about 5% to about 10%, most preferably from 7.8% to about 9.8% by weight. -% biodegradable fiber material, preferably cellulose-containing fibers.

Furthermore, the bakable composition preferably contains from about 6% by weight to about 30% by weight, preferably from about 10% by weight to about 25% by weight, most preferably from about 16.1% by weight to about 20.05 % By weight native starch.

Furthermore, the bakable composition preferably contains from about 2% by weight to about 10% by weight, preferably from about 4% by weight to about 8% by weight, most preferably from about 5.4% by weight to 6.8 % By weight pre-gelatinized starch.

Furthermore, the bakable composition preferably contains from about 45% by weight to about 90% by weight, preferably from about 60% by weight to about 80% by weight, more preferably from about 60% by weight. % to about 75% by weight, most preferably from about 63% to about 71% by weight of water.

Protein in the bakeable mass is preferably in an amount of up to 10% by weight, preferably up to about 5% by weight, more preferably about up to 3% by weight of protein, most preferably up to about 2% by weight. % contain.

The above data in percent by weight are based in each case on the total weight of the bakable mass.

A fat-containing release agent can be added during the preparation of the bakable mass. Of course, it is also possible to put the fat-containing release agent directly into the baking mold immediately before the baking process.

The biodegradable moldings produced in accordance with the above explanations have a fiber material-starch composite or, if protein is used, a fiber material-starch-protein composite.

The elastic coating is arranged on the connecting element. The molded body produced using the waffle baking process and thus also the connecting elements have a relatively closed surface. However, the coating applied in the preferably liquid state can also partially penetrate into the surface. This partial penetration of the coating into the connecting element, if appropriate, improves the adhesion of the coating on or to or in the connecting element. Furthermore, it is not excluded that the partial penetration of the coating material into the connecting element also leads to an improvement in the elasticity of the starchy structure of the connecting element itself.

The application of the elastic coating does not necessarily have the effect that the starch-containing composite or the starch-fiber-containing composite of the connecting element does not break off or tear through during use, ie when the connecting element bends or kinks during opening or closing of the shaped body becomes. However, if the starchy composite material of the connecting element breaks or tears, separation of the molded elements previously connected to one another via the connecting element is reliably prevented by the applied coating. In this case, the coating thus acts as an elastic link which still connects the shaped elements to one another. In contrast to the teaching of US Pat. No. 5,843,544, no attempt is made according to the present invention to improve the flexibility or elasticity of the hinge region, ie the starch-containing composite material itself, in order to prevent the hinge from being broken or torn. Rather, in the case of the biodegradable molded body according to the invention, any breaking or tearing or tearing of the connecting element that may occur is accepted. In such a case, a separation of the container element and the cover element is effected exclusively via the applied elastic coating.

It has been shown completely surprisingly that no complex hinge constructions are required and that the connecting element of the molded body according to the invention reliably allows the molded body to be opened and closed several times without the container element and cover element being separated. The present invention thus represents a technically simple, inexpensive and reliable solution to a problem that has existed for years.

Since elaborate hinge constructions are dispensed with in the molded body according to the invention, a simple connecting element between the molded bodies, for example in the form of a strip or ribbon, is sufficient.

It is preferred that the connecting element extends substantially flat and has a first and a second outer surface, at least a partial area of the first and / or second outer surface being provided with the elastic coating.

In the case of a flat configuration of the connecting element, the coating can be applied and arranged particularly easily. Of course, several connecting elements between the shaped elements, e.g. a cover element and a container element can be arranged. For example, two or three connecting elements can be provided, which are arranged evenly spaced from one another between the shaped elements.

Depending on the later intended use of the shaped body, the coating can be provided on one or else on both outer surfaces of a flat connecting element. Furthermore, the coating can only be provided in the area of the connecting element which experiences the greatest bending when the molded body is used, ie the area in which the greatest tension occurs in the starch-containing composite. For reasons of simplicity, however, it can be preferred that the coating is applied in principle to both outer surfaces of the connecting element and that the connecting element between the shaped elements is completely coated.

Furthermore, the object on which the invention is based is achieved by a shaped body as described above, in which the connecting element is essentially free of polyols. The connecting element preferably contains no polyol.

In order to ensure reliable adhesion of the elastic coating to the starchy composite of the connecting element, it is therefore preferred not to apply any plasticizers in the form of polyols, such as, for example, glycerol, polyethylene glycol, propylene glycol, polypropylene glycol and sorbitol, to the connecting element.

It has been shown that when polyol is used as the plasticizer, it penetrates the starch-containing composite and leads to poorer adhesion or easier detachment of the coating on the connecting element.

It has thus proven to be advantageous in the present invention to accept a break in the starch-containing composite, if necessary, but to achieve reliable adhesion of the elastic coating on the connecting element.

According to a further embodiment of the invention, the elastic coating is an elastic lacquer film with a film former, at least one component of the film former comprising a synthetic resin.

It has been shown that when the shaped body according to the invention is produced, the coating is applied in the form of a lacquer, i.e. using the conventional painting processes is particularly simple, which is explained in more detail below.

The film-forming component is preferably selected from the group consisting of polyurethane, polyester, polyether and mixtures thereof.

The aforementioned film formers can advantageously be used as an aqueous dispersion, ie as water-based paints. On the one hand, the use of water as a solvent enables the molded articles according to the invention to be produced in an environmentally friendly manner. Furthermore, the use of water in With regard to occupational safety, this is to be welcomed, since water-based paints pose a lower risk for the persons involved in this work process.

In the case of polyesters, it can be advantageous for the free carboxyl groups to be converted into the corresponding salts by neutralization, for example using amines, preferably volatile amines, in order to increase their water solubility. When the lacquer film is formed, the amines evaporate and result in a lacquer film that is relatively resistant to moisture and moisture.

Polyether groups can also be provided in the film former in order to enable the synthetic resin to be dispersed in an aqueous medium via the ether group. For example, polyethylene oxide groups can be provided in the film former.

Polyurethane dispersions have also proven to be very suitable. Polyurethane dispersions have a good environmental impact. Furthermore, they can be processed in one component, since they dry physically. In addition, chemical crosslinking is also possible if this is desired. Polyurethane lacquer films have high mechanical strength (abrasion resistance) and have the desired flexibility (elasticity). It is extremely advantageous to use no external emulsifiers in the production of polyurethane dispersions.

According to a further embodiment of the invention, the film-forming component comprises polyurethane and acrylate and / or polyacrylate.

Since pure polyurethane dispersions are relatively expensive, the somewhat cheaper mixtures of polyurethane dispersion and polyacrylate dispersion are preferably used. Paints based on a polyurethane-polyacrylate dispersion form, after drying, paint films with sufficient elasticity for the purposes at hand.

It is further preferred that the elastic coating is essentially free of plasticizers in the form of polyols.

As already stated above, polyols have a disadvantageous effect on the adhesiveness of the elastic coating to the starchy composite. It is therefore advantageous if the paint film itself is largely, preferably completely free, of polyols. The thickness of the applied coating is preferably in a range of less than 500 μm, more preferably less than 100 μm, more preferably less than 50 μm, most preferably less than 20 μm, most preferably less than 5 μm.

The object on which the present invention is based is further achieved by providing a method for producing a biodegradable molded body based on a starch-containing composite material with at least two molded elements connected to one another via at least one connecting element, wherein a starch-containing bakable mass is baked in a baking mold, after baking at least a partial area of the connecting element is applied with a polymer dispersion and subsequently a largely elastic coating is formed while volatilizing the solvent.

The ^" object ^" on which the present invention is based is further achieved by providing a method for producing a biodegradable molded article based on a starch-containing composite material with at least two molded elements which are connected to one another by at least one connecting element by baking a starch-containing bakable mass in a baking pan, in which after baking an essentially polyol-free polymer dispersion is applied to at least a portion of the connecting element and a largely elastic coating is subsequently formed while volatilizing the solvent.

The application of a polymer dispersion can be applied in the method according to the invention by conventionally known application methods such as brushing, rolling, drawing, wiping, pouring, rolling, dipping, flooding, vacuum painting, spraying, atomizing, etc.

These application processes all enable a good or very good order efficiency. The above-mentioned application methods are selected by the person skilled in the art with regard to the accessibility of the surfaces to be coated and the desired working speed.

It has been shown that the use of polymer dispersions and the conventional painting processes for applying an elastic coating to the connecting element is very suitable. After the polymer dispersion has been applied, the solvent is volatilized or evaporated to form the elastic coating.

It is further preferred that the connecting element extends essentially flat and is formed with a first and a second outer surface, the polymer dispersion being applied to at least a portion of the first and / or second outer surface.

The application of a polymer dispersion to a flat connecting element is technically easier to implement than, for example, connecting elements with a round or oval cross section.

According to a further embodiment of the method according to the invention, the solvent of the polymer dispersion is volatilized after application of the polymer dispersion to the connecting element under the application of heat and / or energy.

The heat can be brought about by convection drying (forced air drying). Drying can also be effected by irradiation of UV radiation, IR radiation or microwave radiation. Inductive drying, in which heat is developed through induced alternating currents, can also be used.

In a further embodiment according to the invention, the solvent of the polymer dispersion is preferably volatilized after the polymer dispersion has been applied to the connecting element using the residual heat of the baked molded body.

When the elastic coating is applied immediately after the baking process, the residual heat contained in the baked molded body can be used to volatilize (evaporate) the solvent, preferably water. By using the residual heat, it is possible to dispense with the additional radiation of energy. This process variant thus advantageously enables energy to be saved.

Of course, it is also possible to radiate additional energy even when the residual heat of the baked molded body is used. In an advantageous embodiment, for example, the warm exhaust air drawn off during the baking process can be used to dry the coated moldings. It is further preferred that the polymer dispersion contains at least one film former, at least one component of the film former comprising a synthetic resin.

Aqueous dispersions of aliphatic polyesters and polyurethanes are particularly useful. Furthermore, aqueous dispersions of polyester polyurethanes and polyether polyurethanes have proven to be very suitable in the process according to the invention.

The film-forming component further preferably comprises polyurethane and acrylate and / or poly acrylate.

With regard to the preferred film formers, reference is made to the above statements.

The solvent is preferably predominantly, particularly preferably exclusively, water.

Of course, the polymer dispersions may also contain other additives, such as defoamers, dispersants, thixotropic agents, coalescing agents, etc.

The object on which the invention is based is further achieved by the use of an aqueous polymer dispersion for producing an elastic coating on a connecting element in a biodegradable molded body according to one of claims 1 to 7.

The at least two molded elements of a biodegradable molded body can thus be opened and closed again and again very advantageously without the risk of the molded elements (container element, cover element) separating from one another.

The shaped body according to the invention, which consists of at least one connecting element and two shaped elements, can be provided by means of wafer baking technology. The baking tins for the two shaped elements, for example the two halves a hamburger box, are connected to each other via a strip or ribbon-shaped web. When filling a baking mass and closing the baking mold, the baking mass spreads evenly in the baking mold with evaporation of water and as a result of pressure increase. During this baking process, the strip-like or band-shaped web is then filled evenly with baking mass and a shaped body according to the invention is provided by baking.

Due to the simple geometry of the web, i.e. Due to the strip or band-shaped design of the connecting element, the molded bodies according to the invention can be produced with a high throughput, without producing errors in the connecting element. Furthermore, the baking pan can be made consistently of the same material, for example metal or steel. This enables inexpensive and simple manufacture of the baking molds. Furthermore, these baking tins have a very long shelf life and are practically prone to failure.

The choice of the length and the thickness of the connecting element can be influenced by various factors, such as the size of the shaped elements to be connected to one another. Furthermore, the fiber content in the bakable mass, the length and width and the type of fibers used can have an influence on the length and thickness of the connecting element to be selected.

In general, the connecting element has a thickness of approximately 0.1 mm to approximately 1.5 mm, preferably approximately 0.25 to approximately 1.2 mm, more preferably approximately 0.3 mm to approximately 0.8 mm. The length of the connecting element, which is defined by the spacing of the molded elements connected to one another, can be approximately 0.25 cm to approximately 6 cm, preferably approximately 0.5 cm to approximately 3 cm. The width of the connecting elements can be freely varied depending on the intended use. The width of the connecting element can extend over the full or partial width of the interconnected molded elements.

An increased residual moisture content in the molded body or connecting element of, for example, from 4 to 15%, preferably from 10%, increases the flexibility.

According to the invention, the at least two shaped elements are connected to one another via at least one connecting element such that they can be arranged one above the other. That is, when forming a first shaped element as a container and a second molded element as a cover, then at least one connecting element is arranged between the container and the cover in such a way that the container can be closed with the cover without the connection between the container element and the cover element having to be released.

The invention is explained below with reference to the attached FIG. 1.

Figure 1 shows a perspective view of an exemplary embodiment of the

Invention. You can see a hamburger box (1), which includes a receptacle (2) and a cover container (3), in the open state. The receptacle

(2) and the cover container (3) are connected to one another via a strip-like or band-like flat connecting element (4). The hamburger box (1) is closed by moving the cover container (3) along the arrow shown over the receptacle (2) and arranging it thereon. The connecting element (4), which is provided with an elastic coating, is bent by approximately 180 ° without causing a separation of the receptacle (2) and the cover container

(3) is coming.

The following example serves only to further illustrate the invention. Of course, moldings with dimensions other than those described below can also be produced.

Example: Hamburger box

A hamburger box, as exemplified in Fig. L, with the usual dimensions (width of a square half: about 12-14 cm, depth of a half: about 3-4 cm), with the two halves along one side over a distance of about 9 cm via a strip-shaped connecting element with a length (distance between the two halves of the hamburger box from each other) of about 0.5 cm to about 1 cm was provided with an elastic coating on both outer surfaces of the connecting element. The connecting element had a thickness of approximately 200 μm to approximately 500 μm.

The following dispersion paints were used in each case to form an elastic coating. The dispersion lacquers were each applied to the two outer surfaces of the connecting element by brushing and, after drying by irradiation with IR radiation, gave an approximately 5 μm thick coating. In the case of the moldings obtained in each case, the coating adhered very well to the starch-fiber composite and had very good elasticity. 1. Senolith ^® -WL elastic coating LA 2-14 / 115 A from Weilburger Lackfabrik GmbH & Co. KG, D-91466 Gerhardshofen, Germany, which is an aqueous dispersion of aliphatic polyesters and polyurethanes.

2. Lacquer 076-090-05840 from Kristall Lack H. Müller GmbH & Co. KG in D-42277 Wuppertal, Germany, which is a dispersion of polyester-polyurethane and polyether-polyurethane.

LIST OF REFERENCE NUMBERS

1 molded body

2 molded element (container) 3 molded element (cover) 4 connecting element

Claims

claims

1. Biodegradable molded article based on a starch-containing composite material with at least two molded elements connected to one another via at least one connecting element, characterized in that at least a partial area of the connecting element is provided with a largely elastic coating.

2. Biodegradable molded article based on a starchy composite material with at least two interconnected via at least one connecting element

Shaped elements, characterized in that at least a portion of the connecting element is provided with a largely elastic coating, the connecting element being essentially free of polyols.

3. Biodegradable molded body according to claim 1 or 2, characterized in that the connecting element extends substantially flat and has a first and a second outer surface, at least a portion of the first and / or second outer surface being provided with the elastic coating.

4. Biodegradable molded article according to one of the preceding claims, characterized in that the elastic coating is an elastic lacquer film with a film former, at least one component of the film former comprising a synthetic resin.

5. Biodegradable molded article according to one of the preceding claims, characterized in that the film-forming component is selected from the group consisting of polyurethane, polyester, polyether and mixtures thereof.

6. Biodegradable molded article according to one of the preceding claims, characterized in that the film-forming component comprises polyurethane and acrylate and / or polyacrylate.

7. Biodegradable molded article according to one of the preceding claims, characterized in that the coating is essentially free of plasticizers in the form of polyols.

8. A method for producing a biodegradable molded body based on a starch-containing composite material with at least two over at least one

Connecting element interconnected molded elements by baking a starchy bakable mass in a baking mold, characterized in that after baking, a polymer dispersion is applied to at least a portion of the connecting element and then a largely elastic coating is formed while the solvent is volatilized.

9. A method for producing a biodegradable molded body based on a starch-containing composite material with at least two molded elements connected to one another via at least one connecting element by baking a starch-containing bakable mass in a baking mold, characterized in that after baking on at least a portion of the connecting element a substantially Applied polyol-free polymer dispersion and then a largely elastic coating is formed with volatilization of the solvent.

10. The method according spoke 8 or 9, characterized in that the connecting element extends substantially flat and is formed with a first and a second outer surface, wherein the polymer dispersion is applied to at least a portion of the first and / or second outer surface.

11. The method according to any one of claims 8 to 10, characterized in that the solvent of the polymer dispersion after application of the polymer dispersion to the connecting element is volatilized under the action of heat and / or energy.

12. The method according to any one of claims 8 to 11, characterized in that that the solvent of the polymer dispersion is volatilized after the application of the polymer dispersion to the connecting element by utilizing the residual heat of the baked molded body.

13. The method according to any one of claims 8 to 12, characterized in that the polymer dispersion contains at least one film former, wherein at least one component of the film former comprises a synthetic resin.

14. The method according to any one of claims 8 to 13, characterized in that the film-forming component is selected from the group consisting of polyurethane, polyester, polyether and mixtures thereof.

15. The method according to any one of claims 8 to 14, characterized in that the film-forming component comprises polyurethane and acrylate and / or polyacrylate.

16. The method according to any one of claims 8 to 15, characterized in that the solvent is predominantly, preferably completely, water.

17. Use of an aqueous polymer dispersion for producing an elastic coating on a connecting element in a biodegradable molded body according to one of claims 1 to 7.