Use of a fiber foam for plant cultivation, fractionated fiber foam and seedling based on a fiber foam

Abstract

The invention relates to the use of a fiber foam for plant cultivation, wherein the fiber foam is based on lignocellulose-containing substances and is porous.

Description

The invention relates to a use of a fibrous foam for plant cultivation, a fractionated fibrous foam and a seedling based on a fibrous foam.From the prior art, a foam plug for flowers or similar plants is known. The plug foam is a foam which consists of synthetic resin or phenol-formaldehyde resin. In particular, the foam material stores water and can thereby supply the inserted plants or flowers with water over a limited time.The foam plug is suitable only for temporary use, for example for the presentation of plants in a store or for transport. On the other hand, it is not suitable for the cultivation of plants. In addition, the known foam plug is formed from synthetic resin or phenol-formaldehyde resin and represents a source of microplasty that is not negligible with respect to ecological degradation.Against this background, it is an object of the invention to provide technical teachings for plant cultivation which can be used in horticultural applications in a versatile manner and offer ecological advantages.This object is achieved by the use of a fibrous foam for plant cultivation according to claim 1, a fractionated fibrous foam according to claim 9 and a seedling based on a fibrous foam according to claim 13.Preferred embodiments are the subject of the dependent claims.The basis of the invention is the surprising finding that fibrous foams which are produced without the use of synthetic binders and are usually used as heat and sound insulation, for furniture production, as packaging material or filter material are suitable for plant cultivation or horticultural use.According to the invention, a fibrous foam is used for plant cultivation, wherein the fibrous foam is based on lignocellulosic substances and is porous.Lignocellulosic substances, in particular fibers, are substances or fibers containing lignin. Examples thereof are all types of wood such as hardwood or softwood, including bark or root material, saw by-products, perforation wood, old wood, and various annual plants, as well as modified lignocellulosic raw materials. Within the scope of the invention, softwood or softwood fibers, for example, spruce, egg, tanne, pine or larch, is particularly preferably used.The fibrous foam can be obtained by various production methods which are characterized in that, for stabilizing the fibrous foam from lignocellulosic fibers, no chemically induced digestions and no additional synthetic binding substances are required, since, for example, in the case of mechanical disintegration at a temperature between 120° and 180° C., binding substances are exposed from the plant parts.The production method for producing the porous fiber foam provides that precomminuted lignocellulosic fibrous materials, as have been mentioned above, are processed at temperatures between 120° C. and 180° C. and at a pressure of 2 to 8 bar, preferably together with water, to form a fiber suspension, in particular disintegrated in a grinding process, and that this fiber suspension is subsequently filled into a mold or applied to a carrier and dried without the addition of a synthetic binder. At the temperatures mentioned, the lignin contained in the substances or fibers used liquifies and binds during the subsequent drying.The fiber suspension is preferably aqueous, wherein it is provided in the production method that a highly viscous suspension having a solids-water ratio of 1:2 to 1:20, preferably of 1:5 to 1:10, is produced from the aqueous fiber suspension before introduction into the mold or application to the carrier. A pH of the highly viscous suspension is preferably between 4 and 10, further preferably <=5.The dewatering can be effected by decanters or other mechanical dewatering in order to make less use of thermal energy during drying. In particular, the highly viscous suspension can be predewaterd by means of vacuum or by mechanical pressure before the thermal drying, in order to reduce the thermal energy consumption.The thermal drying can be carried out by a convective and / or conductive heat flow and / or by thermal radiation and / or by electromagnetic radiation, wherein the drying is preferably carried out in a dryer at temperatures of initially between 110° C. and 140° C. The drying is preferably carried out by electromagnetic radiation, such as microwave radiation. However, drying is not limited thereto. However, other heat sources can also be used, for example residual heat or waste heat from other processes.The suspension introduced into the mould or applied to the carrier is preferably dried at the high temperatures for between 0.5 and 2 hours in order to activate the autoadhesive bonds. Preferably, the drying process only needs to be carried out until the autoadhesive bond is activated, so that residual moisture can remain.Preferably, however, the drying temperature can subsequently be lowered to below 80°, preferably to 70° C., in order to remove the residual moisture. The removal of the residual moisture is preferred, for example, when the fiber foam is to have minimal weight for a wide transport.The remaining drying time is dependent in particular on the drying type and can be between 5 and 12 hours in a drying cabinet and between 10 and 30 minutes in the case of drying with electromagnetic radiation.The use of a foam-like (highly viscous) suspension of lignocellulosic fibers is essential for the fiber foam. These are required for a certain gas-retaining capacity and for the good cohesion of the finished fiber foam, but a synthetic binder is not required.Natural binding substances contained in the fiber foam can also be added in the production process.The obtained fibrous foam, which is based on the lignocellulosic fibrous materials, is very well usable for horticultural applications and in particular for plant cultivation and is used for this purpose according to the invention.The porosity of the fiber foam is obtained, for example, by stirring the fiber suspension or the highly viscous suspension in the production process or by adding a blowing agent to the highly viscous suspension.The fibrous foam used according to the invention is open-pored.The blowing agents are in particular gas formers (CO2spalt), N20, propane, n-butane or pentane or fully decomposing blowing agents, in particular hydrogen peroxide, and can be added to the highly viscous suspension before introduction into the mold or application to the carrier.Additionally or alternatively, gases can be introduced into the highly viscous suspension for foam formation by mechanical, pneumatic and / or thermal processes before introduction into the mold or application to the carrier.Preferably, it is provided in the method that after or during the production of the highly viscous suspension, process additives, fiber foam improving additives or additives are added for setting desired fiber foam properties.For example, the porosity of the fiber foam can be adjusted by adding hydrogen peroxide alone. Furthermore, wood constituents such as lignin, hemicellulose and cellulose can be chemically modified with hydrogen peroxide and high temperatures in such a way that these constituents react with one another and thus build up a bond between the fibers. This bond is water-resistant and thus the fiber foam does not break down in the water, although the fiber foam finally obtained can very well store water and optionally release it.The blowing agents may be used either alone or as mixtures of a plurality thereof in proportions of from 0.25% to 20% by weight based on the dry matter.The degree of porosity of the fibrous foam is preferably selected such that the fibrous foam is suitable for growing or cultivating plants. In particular, a low density or high porosity of the fiber foam suitable for plant growing is selected, which ensures that the fiber foam is light, can store water and roots are sufficiently supported.Preferably suitable for plant cultivation are fibrous foams having densities of between 50 kg / m 3, 60 kg / m 3, 70 kg / m 3 or 80 kg / m 3 and 160 kg / m 3. Particularly preferably, low densities of, for example, below 100 kg / m 3, in particular between 50 kg / m 3, 55 kg / m 3, 60 kg / m 3 or 65 kg / m 3 and 75 kg / m 3 are suitable in this range. However, higher densities are not excluded.It is essential for the use of the fibrous foam for plant cultivation that the production process without synthetic binders can produce a pressure-resistant, porous fibrous foam whose mechanical properties for plant cultivation can be adjusted to a great extent by the fibrous materials used, the fiber length, the degree of foaming of the fiber suspension and the type of drying.The fibrous foam is preferably bonded exclusively by bonding substances which occur naturally in the lignocellulosic substances and are released from the lignocellulosic substances by exposure to temperature.In the production process of the fiber foam, the temperature can be increased stepwise, i.e. at intervals, during the disintegrator grinding operation. The temperature increase can be effected in uniform steps. Preferably, in the production method it is provided that up to 70% of the total disintegration takes place at the target temperature, so that the disintegration is carried out at the maximum temperature provided in order to release the binding substances contained in the lignocellulosic substances.Adaptation to a desired stability or compressive strength of the fiber foam can be achieved by mixing different fiber lengths of the lignocellulosic substances. The spectrum of fiber lengths is between 200 μm and 2500 μm, wherein an increase in the stability or compressive strength of the fiber foam can be achieved by adding longer fibers to the fiber suspension with a proportion of between 5%-50% of fibers with a fiber length of between 1000 μm and 2500 μm.The precomminuted fibrous materials used are preferably carried out in the production process in a thermomechanical process, for example to a groundwood or pressurized groundwood.Furthermore, the compressive strength can be increased by the type of wood pulp and / or the addition of natural binders such as starch, lignin sulfonate, proteins, for example in a proportion of 2 to 20%.The densities and strengths of the fiber foam can be adjusted by means of the fiber lengths used, in particular the mixture of groups of different fiber lengths, and the wood fibers used. An alignment of the fibers is not necessary for this purpose, rather the fibers are present in the fiber foam in an unaligned manner.In the production of the comminuted fibrous materials, the fibers can preferably be comminuted further in a high viscosity grinding or a thermomechanical process (TMP), preferably in an atmospheric refiner without overpressure, to a desired fiber length of between 200 μm and 800 μm. The fiber length achieved is adjusted by using different grinding disk geometries, by adjusting the grinding plate spacing and by adjusting the number of grinding cycles, which can be between 1 and 10. During the further comminution, the fibrous materials are preferably squeezed or broken. In order to adjust the density of the finished fiber foam, different suspensions are preferably mixed or a fiber suspension is produced with batches of fibrous materials of different fiber lengths.According to the invention, the fibrous foam can be used in various forms for plant cultivation. For example, the fibrous foam may have a sheet form, a block form, a granulate form or a fractionated / ground substrate form. It is also conceivable that, as mentioned further below, the fiber foam has exactly the shape of a plant pot.The sheet-form fiber foam is preferably used for "green" exterior purposes of buildings or for walls along roads such as freeways. A wide variety of plants can be cultivated or planted on the slab-shaped fibrous foam. The fibrous foam in sheet form can, according to the invention, already be provided with seeds or shoots.The fiber foam can alternatively be used in a granular form for plant cultivation. For example, the granulate formed from the fiber foam can have particle sizes of 0.1 mm 3 to 1 cm 3.The particles of the granulate can be configured, for example, in the shape of a cube or a sphere.The fibrous foam present in granular form is used, for example, as flower soil, press-pot soil (having coarse granular form), tray substrates (fine fraction or granular form), culture substrates (profibrous), pot substrates (fine to coarse granular form) or container substrates (coarse granular form).In the production process explained, the fibrous foam obtains its appearance by selecting the form into which the fibrous suspension or highly viscous suspension is filled, or by selecting the carrier to which the fibrous suspension or highly viscous suspension is applied.As the support, a screen belt, a nonwoven belt or a conveyor belt may be used to enable continuous production. The belts may be laterally limited and water permeable to allow mechanical preliminary dewatering. A three-dimensionally formed, one-piece or multi-piece form with closed or perforated walls can be used as the mold. The mold is preferably provided with an anti-stick coating, for example of PTFE, or is made of a non-stick material to facilitate demolding.If the sheet form is to be obtained in the production process of the fibrous foam, the form or the support is correspondingly chosen such that the desired sheet form of the fibrous foam is obtained after drying.Alternatively, the fiber foam, for example present in a sheet form, can be subsequently cut or sawn in order to provide it in the desired dimensions or length dimensions.If the fibrous foam is to obtain the aforementioned granulate form, the carrier or the mould is shaped, for example, in such a way that the carrier has a plurality of depressions or the mould has a plurality of cavities. The fiber suspension or highly viscous suspension filled into the depressions or cavities dries in the depressions / cavities to form the individual particles of the granulate. Alternatively, the obtained fibrous foam can also be cut into the granulate form.Further alternatively, the fibrous foam may be present in fractionated or ground form. This form is obtained by fractionating or grinding plates obtained by the above-mentioned production process. The plate form is preferably adapted to the plants used for fractionation or for grinding. The particles obtained may be of the same order of magnitude in terms of volume as the particles of the granulate. The fractionating or grinding step is carried out by means of a comminution plant in which the fractionation / freeness can preferably be adjusted.The fractionated / ground fiber foam is again used, for example, as flower soil, press-pot soil (granulate form, very fine fraction or with very fine fractionated / ground form), as tray substrates (fine fraction or with fine fractionated / ground form), as culture substrates (profibrous), as pot substrates (fine to coarse fractionated / ground form), tree-school substrates (very coarse fractionated / ground form) or container substrates (coarse granulate form).An advantage of fractionating or grinding the plates is that this volume-increasing step must first be carried out in the substrate plant or flower earth plant and the plates can be transported very easily up to this point.Alternatively, the fiber foam can again have a block shape with a size for a (flower) pot, for example. For example, the corresponding block is obtained by cutting the plate obtained in the production process.Preferably, the fractionated / ground or block form fibrous foam can be used in gums, pots or plant boxes.The fibrous foam is particularly preferably used and used according to the invention in hydroponic systems.Also preferably, the fiber foam contains additives and / or has been treated with the additives, wherein the additives comprise colorants, fertilisers, plant strengthening agents, surfactants and / or wetting agents.These additives are selected depending on the application. These additives can be added already in the production process explained, for example, can be mixed with the suspension or highly viscous suspension.Alternatively or additionally, the fiber foam can be treated with the additives by, for example, impregnation.The suitability of the organic fiber foam for plant cultivation can be increased by additions, since both the pH and the nutrients present can be adjusted depending on the application for plant cultivation, for example.As colorants, colors can be used to impart a humus or peat optics to the fiber foam, for example.Preferably, the additives are organic to preserve the ecological aspect of the fiber foam.The fibrous foam is preferably used according to the invention for plant cultivation either by being used alone or by being mixed with another substrate / substrate substitute.If the fibrous foam is mixed with another substrate / substrate substitute, it is preferably fractionated and serves as a substitute for peat, in particular sod peat, or as a soil auxiliary.Moreover, preferably, the fibrous foam is a fractionated fibrous foam and is used as a substitute for synthetic resin foam or expanded clay.A further aspect of the invention is a fractionated or granulated fiber foam for plant cultivation, wherein the fiber foam is based on lignocellulosic substances and is porous, wherein the fiber foam is bonded by bonding substances which naturally occur in lignocellulosic substances and are released from the lignocellulosic substances by exposure to temperature.The fractionated or granulated fibrous foam is obtainable in particular by the production process which has been explained above in connection with the use of the fibrous foam according to the invention. In this respect, reference is made to the statements there of the production method and the preferred embodiments.The production process is supplemented only by the step of fractionating the dried fibrous foam or shaping the particles forming the granulate in the production process.A further aspect of the invention is a seedling based on a fibrous foam, wherein the fibrous foam is provided with at least one plant or one seed.The fibrous foam of the seedling according to the invention is obtainable in particular by the production method which has been explained above in connection with the use according to the invention of the fibrous foam. In this respect, reference is made to the statements there of the production method and the preferred embodiments.The production method is supplemented only by the step of providing the dried fiber foam with a plant or a seed.The fibrous foam of the seedling can preferably be fractionated or granulated.Preferred examples of the production process by means of which the fibrous foam is obtainable are presented below.Example 1:With a solids content of 7%, a suspension of softwood fibers, in particular pine fibers and water, is further defibrated in an atmospheric refiner at room temperature. Subsequently, the highly viscous wood fiber suspension is freed from excess water via a sieve and a solids content of 10% to 15% is established. 1000 g of highly viscous suspension is stirred with 5% to 35% strength of hydrogen peroxide (35% strength in water) in portions for up to four minutes in an intensive mixer at room temperature. The homogeneous, flowable mass is introduced into a form perforated on all sides and dried at 130° C. for 6 to 20 hours in an oven. The resulting lignocellulosic foams / fibrous foams have green densities between 50 kg / m 3 of 250 kg / m 3 and green density-dependent compressive strengths of 20 kPa up to 350 kPa with 10% compression.Example 2:1000 A proportion of 7% to 20% of protein is added to g of highly viscous suspension (softwood fibers, in particular pine fibers) having a solids content of 10% to 15%, and the mixture is first stirred to give a homogeneous mass (cf. Example 1). Subsequently, 5% to 35% of hydrogen peroxide (35% in water) is added uniformly gradually with stirring. The homogeneous, foamy composition is introduced into a mould perforated on all sides and dried at 130° C. for 6 to 20 hours in an oven. The resulting lignocellulosic foams / fibrous foams have green densities between 50 kg / m 3 of 250 kg / m 3 and green density-dependent compressive strengths of 20 kPa up to 600 kPa with 10% compression.Example 3: Example 3:1000 A proportion of 0.5% to 5% ligninsulphonate solution (55% strength in water) is added to g highly viscous suspension (softwood fibres, in particular pine fibres) having a solids content of 10% to 15% and the mixture is first stirred to give a homogeneous composition (cf. Example 1). Subsequently, 5% to 35% of hydrogen peroxide (35% in water) is added uniformly gradually with stirring. The homogeneous, foamy composition is introduced into a mould perforated on all sides and dried at 130° C. for 6 to 20 hours in an oven. The resulting lignocellulosic foams / fibrous foams have green densities between 50 kg / m 3 of 250 kg / m 3 and green density-dependent compressive strengths of 20 kPa up to 240 kPa with 10% compression.Example 4: Example 4:1000 A proportion of 5% to 10% of starch and 7% to 20% of protein is added to g of highly viscous suspension (softwood fibers, in particular pine fibers) having a solids content of 10% to 15%, and the mixture is first stirred to give a homogeneous composition (cf. Example 1). Subsequently, 5% to 35% of hydrogen peroxide (35% in water) is added uniformly gradually with stirring. The homogeneous, foamy composition is introduced into a mould perforated on all sides and dried at 130° C. for 6 to 20 hours in an oven. The resulting lignocellulosic foams / fibrous foams have apparent densities between 50 kg / m3of 250 kg / m3and apparent density-dependent compressive strengths of 20 kPa up to 600 kPa with 10% compression.Example 5: Example 5:1000 A proportion of 10% to 25% of PU dispersion and a proportion of 7% to 20% of protein is added to g of highly viscous suspension (softwood fibers, in particular pine fibers) having a solids content of 10% to 15% and the mixture is first stirred to give a homogeneous composition (cf. Example 1). Subsequently, 5% to 35% of hydrogen peroxide (35% in water) is added uniformly gradually with stirring. The homogeneous, foamy composition is introduced into a mould perforated on all sides and dried at 130° C. for 6 to 20 hours in an oven. The resulting lignocellulosic foams / fibrous foams have apparent densities between 50 kg / m3of 170 kg / m3and apparent density-dependent compressive strengths of 20 kPa up to 350 kPa with 10% compression.The fibrous foam obtainable by all examples of the production process is used according to the invention for plant cultivation and / or for growing plants.In addition, the fibrous foam obtainable by all examples of the production process can be processed to give a fractionated, ground or granulated fibrous foam according to the invention.Finally, the fibrous foam obtainable by all examples of the production process can be processed to give a seedling according to the invention by providing the fibrous foam with at least one seed or shoot.Reference is made to the description and explanations before the examples.

Claims

Use of a fibrous foam for plant cultivation, wherein the fibrous foam is based on lignocellulosic substances and is porous.Use of the fibrous foam according to claim 1, wherein the fibrous foam is bound by binding agents that naturally occur in lignocellulosic materials and are released from the lignocellulosic materials by exposure to temperature.Use of the fibrous foam for plant cultivation according to any of claims 1 to 2, wherein the organic fibrous foam is open-pored.Use of the fibrous foam for plant cultivation according to any one of the preceding claims 1 to 3, wherein the fibrous foam has a sheet form, a granule form, a block form or a fractionated / ground substrate form.Use of the fibrous foam for plant cultivation according to any one of claims 1 to 4, wherein the fibrous foam comprises additives and / or is treated with the additives, wherein the additives comprise colorants, fertilizers, plant strengthening agents, surfactants and / or wetting agents.Use of the fibrous foam for plant cultivation according to any one of claims 1 to 5, wherein the fibrous foam is used either alone or is mixed with another substrate / substrate substitute.Use of the fibrous foam for plant cultivation according to any one of claims 1 to 6, wherein the fibrous foam is fractionated and used as a substitute for synthetic resin foam, expanded clay or peat.Use of a fibrous foam for plant cultivation according to claim 7, wherein additives for plant cultivation such as fertilizers and / or wetting agents are added to the fractionated fibrous foam.Fractionated, ground or granulated fibre foam for plant cultivation, wherein the fibre foam is based on lignocellulosic substances and is porous, wherein the organic fibre foam is bound by binding substances which naturally occur in lignocellulosic substances and are released from the lignocellulosic substances by exposure to temperature.The fibrous foam for plant cultivation according to claim 9, wherein the lignocellulosic materials are wood materials, and wherein the fibrous foam is bonded by lignin, hemicellulose and celluse.The fibrous foam according to any one of claims 9 to 10, wherein the fibrous foam is open-pored.The fibrous foam of any one of claims 9 to 11, wherein the organic fibrous foam comprises additives and / or has been treated with the additives, wherein the additives comprise colorants, fertilizers, plant strengthening agents, surfactants or wetting agents.Seedling for plant cultivation comprising a fibre foam which is based on lignocellulosic substances and is porous, wherein the fibre foam is bound by binding substances which naturally occur in lignocellulosic substances and are released from the lignocellulosic substances by exposure to temperature, and in which at least one shoot or seed is contained.