EP4066807B1 - Urn made from a biodegradable, injection-mouldable material, method for its preparation and its use - Google Patents

Description

The invention relates to an urn made of a biodegradable, injection-moldable material, a method for its production, and its use. In particular, the invention relates to an urn comprising a molded part made of a biodegradable, injection-moldable material containing at least two different polymers, a method for its production, and its use.

The term "urn" used herein is to be understood broadly. This includes ash capsules, decorative urns, in which the ash capsules are generally kept, and combination urns that combine the functions of an ash capsule and a decorative urn. An urn generally consists of a container and a lid. Ash capsules are, in particular, capsules that serve as transport containers for the ashes of humans or animals from the crematorium to the funeral home/cemetery. The ash capsules must be sealed and must not be able to be opened without the use of force. For this purpose, the material must be sufficiently rigid. Decorative urns (also known as outer urns) are generally and commonly used in Germany to enclose ash capsules for burial in a cemetery.

Urns come in a variety of forms, with materials including metal, ceramics, glass, plastics and various wood-based materials being used.

However, when ceramic, metal, or glass are used as materials, weathering cannot occur within a sufficiently short period of time, so in these cases, storage in a columbarium is usually the preferred option. Cemetery regulations generally require that urns and, in general, all items placed in the ground during burial may only be made of materials that decompose without residue within a period appropriate to the period of rest. Wood, on the other hand, weathers within a finite time due to the influence of soil moisture and microorganisms present in the soil.

Furthermore, it has been shown that burial in cemeteries with heavy soils, such as clay soils, as well as very wet soils, where the cemeteries are essentially standing in water, is problematic. The problem is that both in coffin burials and in urn interments often show no significant signs of rot and decay. The consequence is that even after many years of burial, significant remains are often still present when a grave is cleared. In the case of urns, in particular, only imperceptible decomposition occurs, and the ashes they contain are not released into the environment.

Recently, there has been a significant shift in burial practices toward sea burials. Urns that are particularly suitable for sea burials (referred to herein as "sea urns") must meet various requirements. For example, they must decompose in water within 12 to 24 hours. They must also be able to sink quickly. Sulphate urns and cellulose-based urns are generally used for sea urns. Cellulose is more common and permitted in all European countries. In Germany, sulfate urns, particularly those made of calcium sulfate, also known as anhydrite, can also be used. Other possible materials for sea urns include tonolite, halite, papier-mâché, or salt. However, such sea urns cannot be manufactured by injection molding, for example, and/or are not made of biodegradable materials.

The publication DE 88 06 209 U1 discloses a plastic coffin, wherein the plastic can be dissolved into environmentally friendly components within a preprogrammed period of time under the influence of a water-activated solubilizer. These plastics consist of thermoplastic polymers based on conventional monomers, into which reactive groups are polymerized as predetermined breaking points. Under the influence of a base as an external or integrated solubilizer and in the presence of water, a reaction occurs with the reactive group that dissolves the entire plastic in a defined neutralization reaction. Examples of the plastic are not provided.

The publication DE 196 08 261 describes an urn made of an injection-moldable starch-containing material.

The publication DE 197 44 331 A1 describes a coffin and an urn formed as molded parts made of a biodegradable, residue-free, natural-material-based plastic. The plastic can be, in particular, a thermoplastic, a compressed material, or foam. In one embodiment, the plastic is made from one or more of the following raw materials: corn, wheat, potatoes, vegetable oils, sugar beets, milk, wood, grain, and/or polylactic acid.

The publication DE 10 2005 048 203 A1 describes an urn made of biodegradable material containing a starch-free, injection-moldable material which essentially contains wood and natural fibers and wood powder as well as a binding agent, preferably lignin.

The publication DE 10 2007 048 760 A1 Describes a coffin and an urn for the transport, laying in state, and/or burial or cremation of a dead human body or a dead animal, made of a thermoplastically deformable composite material, with a proportion of at least 70% by weight of natural substances in the composite material, wherein at least lignin and cellulose are contained as natural substances in the composite material. In embodiments, the composite material additionally contains starch as a natural substance and/or additionally natural fibers from fiber plants, e.g., a corn plant.

The publication DE 10 2008 012 189 A1 relates to an urn or ash capsule made of a biodegradable thermoplastic polymer reinforced with a biodegradable fiber material, wherein the urn or ash capsule is injection-molded from a mixture of the polymer and the reinforcement, wherein the polymer has a flowability value of 19 MFI to 21 MFI, in particular 20 MFI. The polymer is in particular a polylactide. In the process for its production, granules are produced from polymer mixed with the reinforcement, this granule is melted, and the molded body is injection-molded. In particular, the molded body is injection-molded at a pressure at the nozzle of 450 bar to 500 bar, in particular 475 bar, and at a temperature of 170°C to 230°C, in particular 180°C to 190°C.

The publication KR 200433875 Y1 describes an urn containing a biodegradable material, in particular biodegradable plastic, which is characterized by being made of any one or a combination of two or more materials selected from starch, wheat flour, sawdust, and biodegradable plastic. The biodegradable material additionally contains a binding material selected from natural Carboxymethylcellulose, natural casein, natural stearic acid, polyvinyl alcohol , bentonite, pyrophosphate, polyphosphate, citrate and potassium bromate.

However, starch and polylactide (PLA) biodegrade over longer periods. Both starch and PLA require a relatively well-defined environment for biodegradation, which is generally only found in composting facilities.

Against this background, the object of the invention was to provide an urn made of a biodegradable, injection-moldable material that is particularly suitable for use in burials at sea and in cemeteries with clay soils and/or high water levels. The object of the invention was also to provide a method for producing this urn.

This object is achieved according to this invention by an urn, a method for its production, and its use having the features of the corresponding independent patent claims. Preferred embodiments of the urn according to the invention, the method according to the invention, and the use according to the invention are listed in the corresponding dependent patent claims. Preferred embodiments of the urn according to the invention correspond to preferred embodiments of the method according to the invention and the use according to the invention, and vice versa, even if this is not explicitly stated herein.

The invention thus relates to an urn comprising a molded part made of a biodegradable, injection-moldable material containing at least two different polymers, the material containing (a) a polyvinyl alcohol and (b) a natural or another synthetic, biodegradable polymer, the urn having a polyvinyl alcohol (a) content in the range from 5 to 60 wt.%, a polymer (b) content in the range from 35 to 80 wt.%, and a content of other biodegradable components (c) in the range from 15 to 25 wt.%, in each case based on the weight of the urn, the molded part containing as polymer (b) a polymer from the group consisting of polylactide, starch, polyhydroxyalkanoate and lignin. The polymer (b) can thus, like (a), be another synthetic, biodegradable polymer, or a natural polymer such as lignin.

A preferred polyhydroxyalkanoate (PHA) is polyhydroxybutyrate (PHB), also known as polyhydroxybutyric acid. The polylactide, also known as polylactic acid, preferably has a melt flow index (MFI) in the range of 18 to 22 at room temperature.

Finally, an urn is preferred in which the weight ratio r _ab between the polymers (a) and (b) is in the range of 0.05 to 1.5, more preferably in the range of 0.2 to 1.

Preferably, in the urn according to the invention, the proportion of polyvinyl alcohol (a) is in the range of 5 to 50 wt.%, based on the weight of the urn.

According to the invention, an urn is preferred in which the polyvinyl alcohol (a) has a melt flow index in the range of 10 to 25 g/10 min, measured at 190 °C and 21.6 kg, a melting temperature in the range of 160 °C to 180 °C and a glass transition temperature in the range of 50 °C to 70 °C, measured with a DSC (Differential Scanning Calorimeter), and/or a density in the range of 0.5 to 1.0 g/cm ³ . Polyvinyl alcohols particularly suitable according to the invention are the products marketed by the Japanese company Kuraray under the brand MOWIFLEX ^™ . The polyvinyl alcohol product MOWIFLEX ^™ C17 is particularly suitable. It can be used well for the extrusion of films and profiles, for injection molding, and for 3D printing.

In a particularly preferred embodiment of the urn, the polymer (b) is lignin. Lignin can be used in particular in the form of liquid wood (b1). Liquid wood consists essentially of lignin, although the liquid wood generally also contains wood fibers, in particular 20 to 30 wt.%, based on the weight of the liquid wood. Liquid wood products suitable according to the invention include, for example, granules of the ^Arboform® brand from Tecnaro GmbH, Ilsfeld. The granules ^Arboform® LV3 or ^Arboform® LV100 have proven particularly suitable.

In the urn according to the invention, the proportion of polyvinyl alcohol (a) is preferably between 5 and 50 wt.%, based on the weight of the urn, when the polymer (b) is lignin or liquid wood.

The urn according to the invention preferably contains other biodegradable components (c). Other biodegradable components include, for example, natural wood fibers, particularly from spruce and beech, flax, hemp, Chinese reed, sisal, corn, or other fiber plants, as well as wood chips and wood powder. These natural fibers give the composite material additional strength and facilitate processing using plastics processing machines. Natural wood fibers, particularly from spruce and beech, are best suited for decomposition in the wild (simple decay).

Furthermore, it is also possible to incorporate biodegradable colour pigments into the material to be processed as component (c).

However, mineral colors can also be used for coloring.

Preferably, the other biodegradable components (c) are natural fibres from wood, in particular from spruce and beech.

Also preferred is an urn which has a content of polyvinyl alcohol (a) in the range of 5 to 60 wt.% and a content of liquid wood (b1) in the range of 40 to 95 wt.%, each based on the weight of the urn.

For the urns according to the invention, the elongation at break according to ISO 527 is preferably in the range of 0.3 to 3.0%.

The urn according to the invention generally has a wall thickness in the range of 2 to 10 mm and preferably has a wall thickness of 2.5 to 5 mm.

The urn according to the invention can be provided with a layer that serves to design the surface and covers at least parts of the surface. The color, decoration, and surface structure can vary. The layer can, for example, consist of a film and also contain biodegradable color pigments. The thickness of the layer is typically 0.6 to 1 mm. This layer can be applied, in particular, by water transfer in a conventional manner. If necessary, the vessel can be coated with a biodegradable protective varnish, at least on the outside.

In a particularly preferred embodiment of the urn according to the invention, which is particularly suitable for burial at sea, openings are provided in the urn, which are covered, for example, by a water-soluble film. This allows the urn to sink quickly during a burial at sea, since water can enter the urn and thus reduce its buoyancy quickly. This film can advantageously be made, for example, of the polyvinyl alcohol described herein.

The invention also relates to a method for producing an urn, comprising a molded part made of a biodegradable material containing at least two different polymers, wherein the material contains (a) a polyvinyl alcohol and (b) a natural or another synthetic biodegradable polymer, wherein the urn has a content of polyvinyl alcohol (a) in the range from 5 to 60 wt.%, a content of polymer (b) in the range from 35 to 80 wt.%, and a content of other biodegradable components (c) in the range from 15 to 25 wt.%, in each case based on the weight of the urn, wherein the molded part contains as polymer (b) a polymer from the group consisting of polylactide, starch, polyhydroxyalkanoate and lignin, and wherein the material is brought into a desired shape of an urn by injection molding, deep drawing or 3D printing.

Generally, (a) polyvinyl alcohol and (b) a natural or another synthetic, biodegradable polymer (b) are used in the form of granules, which are then melted and further processed in a suitable plastics processing machine. Separate granules of (a) and (b) can be mixed, or previously prepared granules from components (a) and (b) can be used. Preferably, separate granules of (a) and (b) are mixed and melted in the injection molding machine. The granules of component (b) preferably already contain other biodegradable components (c). In this case, the granules are designated (b1).

The granules can be processed, for example, on conventional extruders or injection molding machines without the need for any modifications to these plastics processing machines. For example, standard polyolefin screws can be used. Depending on whether processing is to be carried out in an extruder or an injection molding machine, an appropriately adapted material made up of components (a), (b) and, if applicable, (c) can be used.

The urn is preferably manufactured by injection molding. However, the urn according to the invention can also be manufactured by extrusion and subsequent deep drawing. In this case, a sheet is first produced from components (a), (b) and optionally (c) by extrusion, which is then formed into an urn by deep drawing, with the upper and lower parts of the urn being formed in one continuous piece from one sheet or as separate parts from two sheets. If necessary, a film, which may be printed with biodegradable printing inks, can also be produced by coextrusion with the inventive

A film can also be inserted into an injection mold. However, the film is preferably applied by water transfer in a conventional manner.

A process in which the urn is produced by injection molding is particularly preferred. Advantageously, the injection molding is carried out at a temperature in the range of 160°C to 200°C, in particular at a temperature in the range of 170°C to 190°C, and/or at a pressure of 800 to 1200 bar. Higher contents of polyvinyl alcohol (a) generally require higher pressures. Furthermore, the pressure will also depend on the molded part to be produced. The production of a lid will generally require a lower pressure than the production of the actual container in which the ashes are stored.

Furthermore, the urn according to the invention can be manufactured using 3D printing.

The invention also relates to the use of an urn described herein for burial at sea or for burial in highly water-rich soil. Use for burial at sea is particularly preferred.

The invention offers numerous advantages. The urn according to the invention is made exclusively from environmentally friendly materials, making it ecologically safe. A particular advantage arises from the fact that a water-soluble and ecologically safe material, namely polyvinyl alcohol, is added to the biodegradable material. This initially destroys the container (urn), releasing the ashes into the environment. The biological degradation of the remaining material is therefore a negligible time factor.

Examples

• Temperatur: 180 °C
• Druck (abhängig vom Gehalt an Polyvinylalkohol): 800 bis 1.200 bar

In the examples, several injection-molded urn-shaped parts with layer thicknesses of 2.6 mm each were produced. The injection molding conditions were as follows:

• Temperature: 180 °C
• Pressure (depending on the polyvinyl alcohol content): 800 to 1,200 bar

The polymer (b) and the other biodegradable components (c) were used as liquid wood (b1) of the ^Arboform® LV3 or ^Arboform® LV100 brand from Tecnaro GmbH, which contained lignin as polymer (b) in an amount of 70 to 80 wt.% and spruce and/or beech wood fibers as component (c), each based on the total weight of the liquid wood. MOWIFLEX ^™ C17 from Kuraray was used as polyvinyl alcohol (a). The granules of components (a) and (b1) were mixed and melted in an injection molding machine.

The mixing ratios were changed, and the behavior (degradation) under the influence of water was investigated. Degradation behavior was investigated by placing the molded parts in freshwater at temperatures of 15 to 20 °C. The results are summarized in the following table. When investigating degradation behavior in saline and/or colder water, it was found that degradation proceeded more slowly. Table Example No. Composition* Degradation behavior Liquid wood (b1) Polyvinyl alcohol (a) 1 90% 10% The molded parts showed cracks and minor material erosion over the course of several weeks 2 75% 25% The molded parts showed first holes within 5 to 7 days 3 60% 40% The capsules dissolve well within 48 hours. Only the liquid wood remains, with a soft consistency. If you remove the remaining pieces from the water, the material hardens again. 4 ≤ 40%** ≥ 60%** - * in weight percent, based on the sum of (a) and (b1); the liquid wood (b1) contained lignin as polymer (b) in an amount of 70 to 80 wt.% and, as component (c), 20 to 30 wt.% wood fibers from spruce and/or beech, in each case based on the total weight of the liquid wood.
**The molded parts were not dimensionally stable, so an investigation of the degradation behavior was unnecessary.

Claims (12)

1. An urn comprising a moulded part made of a biodegradable, injection-mouldable material containing at least two different polymers, characterised in that the material contains (a) a polyvinyl alcohol and (b) a natural or another synthetic biodegradable polymer, the urn having a content of polyvinyl alcohol (a) in the range from 5 to 60% by weight, a content of polymer (b) in the range from 35 to 80% by weight, and a content of other biodegradable components (c) in the range from 15 to 25% by weight, and a content of other biodegradable constituents (c) in the range from 15 to 25 % by weight, in each case based on the weight of the urn, wherein the moulded part contains as polymer (b) a polymer from the group consisting of polylactide, starch, polyhydroxyalkanoate and lignin.
2. Urn according to claim 1, characterised in that the weight ratio r_ab between the polymers (a) and (b) is in the range from 0.05 to 1.5.
3. Urn according to one of claims 1 to 2, characterised in that the proportion of polyvinyl alcohol (a) is in the range from 5 to 50% by weight, based on the weight of the urn.
4. Urn according to one of claims 1 to 3, characterised in that the polyvinyl alcohol (a) has a melt flow index in the range from 10 to 25 g/10 min, measured at 190 °C and 21.6 kg, a melting temperature in the range from 160 °C to 180 °C and a glass transition temperature in the range from 50 °C to 70 °C, measured with a DSC, and/or a density in the range from 0.5 to 1.0 g/cm³.
5. Urn according to one of claims 1 to 4, characterised in that the polymer (b) is lignin.
6. Urn according to one of claims 1 to 5, characterised in that the other biodegradable components (c) are natural fibres from wood, in particular from spruce and beech.
7. A method for producing an urn comprising a moulded part made of a biodegradable material containing at least two different polymers, the material containing (a) a polyvinyl alcohol and (b) a natural or another synthetic biodegradable polymer, the urn having a content of polyvinyl alcohol (a) in the range from 5 to 60 % by weight, a content of polymer (b) in the range from 35 to 80 % by weight, and a content of other biodegradable components (c) in the range from 15 to 25 % by weight, in each case based on the weight of the urn, the moulded part containing as polymer (b) a polymer from the group consisting of polylactide, starch, polyhydroxyalkanoate and lignin, characterised in that the material is brought into a desired shape of an urn by injection moulding, thermoforming or 3D printing.
8. Method according to claim 7, characterised in that the urn is produced by injection moulding.
9. Method according to claim 8, characterised in that the injection moulding is carried out at a temperature in the range from 160 °C to 200 °C and/or at a pressure of 800 to 1,200 bar.
10. Method according to one of claims 7 to 9, characterised in that the polyvinyl alcohol (a) has a melt flow index in the range from 10 to 25 g/10 min, measured at 190 °C and 21.6 kg, a melting temperature in the range from 160 °C to 180 °C and a glass transition temperature in the range from 50 °C to 70 °C, measured with a DSC, and/or a density in the range from 0.5 to 1.0 g/cm³.
11. Method according to any one of claims 7 to 10, characterised in that the polymer (b) is lignin.
12. Use of an urn according to any one of claims 1 to 6, for burial at sea or for burial in a soil with a high water content.