Method for the hydrophobisation of a plant starting material

Abstract

The invention relates to a method for the hydrophobisation of a plant starting material, in which the starting material is treated with a hydrophobing agent, in which a mixture is produced from the starting material, which is preferably present in a dried state, and at least one metal soap as the hydrophobing agent, and the treatment is carried out by heating the mixture. The invention also relates to a use of hydrophobised starting materials produced in this way as an insulating material, in particular by shaping the mixture, or as a solid material, in particular by shaping the mixture, preferably during compression.

Description

[0001] Method for making a plant-based starting material hydrophobic

[0002] The invention relates to a method for hydrophobizing a plant-based starting material, in which the starting material is treated with a hydrophobizing agent.

[0003] Such processes serve to protect the usually hydrophilic plant material against the negative effects of water on the plant material or at least to reduce such effects, in order to make plant material accessible for economically sensible use in the sense of sustainable raw material use, e.g. in construction.

[0004] Methods of this type are known in the prior art, e.g. through the publication

[0005] DE 10 2015 003 373 A1 of the same applicant. In this known process, plant starting material is treated in a wet process with a hydrophobizing agent in order to achieve wetting of the starting material with the hydrophobizing agent.

[0006] This is disadvantageous because the hydrophobized starting material then requires energy-intensive drying before further use. Furthermore, the known method only discloses the use of hydrophobizing agents that render the treated starting material not readily biodegradable, and in particular, no longer suitable for composting. Against this background, an object of the invention is to provide a method for producing a hydrophobized starting material that is more easily recycled, particularly suitable for composting, and preferably requires less energy.

[0007] This problem is solved by producing a mixture of the plant starting material and at least one metal soap as a hydrophobizing agent in a process of the type mentioned above, and by heating the mixture.

[0008] According to the invention, the mixture of the starting material and the at least one metal soap thus uses a single metal soap or alternatively several (at least two), i.e. a mixture of several (at least two) metal soaps.

[0009] While this process also requires energy for heating, it does so over a significantly shorter time compared to drying. The process has the advantage of completely avoiding any potentially adverse effects of a wet process, as seen in the prior art.

[0010] The heating process thermally activates the mixture, thereby increasing the mobility of the metal soap in the mixture, which, according to the invention, causes the hydrophilic group of the metal soap, in particular its carboxylate group, to adhere to the surface of the plant starting material.

[0011] The invention preferably provides that the starting material is comminuted before being mixed with at least one metal soap, in particular by chopping or grinding, especially to a size of less than or equal to 10 mm, preferably less than or equal to 5 mm, and particularly preferably less than or equal to 0.5 mm. For example, the starting material is brought into a granular or powdered form by comminution and mixed with at least one metal soap. Preferably, the at least one metal soap or metal soap mixture added to the mixture has a cross-sectional size, particularly in the case of granular or powdered form, that is less than or equal to the cross-sectional size of the starting material. A cross-sectional size of the metal soap or metal soap mixture that is in any case less than or equal to 1 mm is particularly preferred.

[0012] Preferably, the plant-based starting material in the mixture is present in a dry form. In particular, the at least one metal soap is always present in a dry form. Preferably, the mixture components are in a non-wetting form, at least before heating.

[0013] The invention can generally provide that plant-based starting material is first dried after its extraction, in particular after harvesting, in order to remove or at least reduce water components from the starting material, thus adding the starting material to the mixture in dried form.

[0014] In this context, "dried" preferably means that the dried starting material has a lower water content than the fresh or freshly harvested starting material, preferably with a residual moisture content of less than 20%.

[0015] In a preferred embodiment, the invention provides that a metal salt of a saturated or unsaturated fatty acid is used as the metal soap, which has a chain length greater than C6, preferably less than C28, preferably wherein the fatty acid is at least one of the following: stearic acid C18H36O2, palmitic acid C16H32O2, lauric acid C12H24O2, α-linolenic acid C18H30O2, oleic acid C18H34O2.

[0016] The invention also preferably provides that the metal soap is one containing an ion of a metal from the following list:

[0017] 1. an alkali metal, especially lithium, or

[0018] 2. an alkaline earth metal, especially magnesium or calcium, or 3. zinc, or

[0019] 4. Aluminum.

[0020] The plant starting material that can be used for the process according to the invention is preferably selected from at least one of the following plant groups: a grass-like plant group, e.g. in particular Miscanthus spp., Switchgrass spp., Phyllostachys spp., or a herb-like plant group, for example in particular Helianthus spp., Silphium spp., Sida spp., or a woody plant group, in particular Paulownia spp., Sambucus spp., Picea spp.

[0021] In particular, it is intended that the starting material is formed by plant tissue, especially a plant from one of the aforementioned groups, preferably one containing parenchymatous tissue.

[0022] In a preferred embodiment, the invention provides that, in the process for producing the mass of hydrophobized starting material according to the invention, metal salts of a fatty acid are used, preferably derived from natural sources. The fatty acids can be obtained, for example, from palm or palm kernel oil, coconut oil, tallow, castor oil, but also from rapeseed or soy.

[0023] The invention preferably creates a barrier to the penetration of water by coating the surface and / or pores and / or capillaries of the plant starting material.

[0024] The invention preferably further provides that a plant-based starting material is used which has natural cavities, in particular pores and / or capillaries, and that after heating the internal cavity walls, in particular pore walls and / or capillary walls, are coated or hydrophobized with the metal soap, preferably without completely filling the cavities. To achieve this, the required amount of starting material and metal soap in the mixture, in particular in weight percent, can be determined empirically beforehand and used in the mixture.

[0025] Preferably, the invention provides that the mixture comprises 80% to 99% starting material and 1% to 20% metal soap, preferably that the mixture comprises 90% to 95% starting material and 5% to 10% metal soap.

[0026] This preferably makes it possible to achieve a complete coating of the plant starting material with water-repellent metal soap, or at least a coating sufficient for the desired hydrophobing effect, according to the invention.

[0027] The invention preferably provides, generally, and particularly in combination with any possible embodiment, that the mixture is heated above the melting temperature of the at least one metal soap used. This ensures reliable thermal activation of the metal soap, resulting in sufficient mobility to allow the hydrophobic group of the metal soap to coat the surface of the plant material.

[0028] Preferably, it is ensured that the heating does not exceed the pyrolysis temperature of the plant material, in order to avoid degradation of the plant material, which can occur even before reaching an ignition temperature of the material above the pyrolysis temperature.

[0029] The pyrolysis temperature is preferably understood to be the temperature at which thermal decomposition of the starting material occurs through chain cleavage. The pyrolysis temperature is therefore still below the ignition temperature at which combustion begins, particularly through spontaneous ignition. The invention may preferably also provide, alternatively or cumulatively, that the temperature during heating is closer to the melting point of the metal soap than to the pyrolysis temperature of the starting material.

[0030] Preferably, the heating temperature is chosen to be between 105% and 115% of the melting temperature of the metal soap.

[0031] The hydrophobized starting material can be used, for example, without further treatment, e.g., as insulation material or building material, e.g., loose fill for the preferably insulated filling of cavities, e.g., as so-called blown-in insulation.

[0032] Thus, the hydrophobized starting material can be used, for example, with a comparatively low density, especially after mixing the granular or powdered starting material with at least one metal soap. In particular, the naturally occurring cavities remain unaffected, promoting good insulation properties.

[0033] The invention may provide that a hydrophobized starting material produced according to the invention is further processed into a semi-finished or finished product, e.g., an insulating or material, in particular by binding and / or pressing the hydrophobized starting material, especially while simultaneously shaping it into a desired shape.

[0034] If compression takes place, especially simultaneously during binding, the density of the hydrophobized starting material is increased compared to the density that is present after heating the mixture of the plant starting material and the at least one metal soap.

[0035] According to the invention, binding can also be carried out without compression using a binding agent.

[0036] By pressing, e.g. by applying force to the hydrophobized starting material in a shaping process, e.g. in a mold in which the hydrophobized starting material is contained, the hydrophobized starting material can be bound in addition to being shaped, especially without the need for an additional binder.

[0037] This bonding can be achieved through mechanical connection of the hydrophobized starting material and / or through a binder.

[0038] In general, by binding with or without simultaneous pressing, the shaped, bound, hydrophobized starting material can form a semi-finished product that can be further processed or even a usable end product directly.

[0039] According to the invention, the hydrophobized starting material can preferably be bound with or without compression using a binder naturally present in the starting material, in particular to form a semi-finished product or finished product, preferably by simultaneous compression, in particular to form a plate.

[0040] Such a panel can be used, for example, as an insulation panel.

[0041] Without compression during binding, a better insulating semi-finished or finished product is achieved than with compression, as the cavities are not compressed. Conversely, compression binding results in a higher density and therefore greater strength of the resulting semi-finished or finished product compared to non-compression binding.

[0042] In all the aforementioned embodiments, the invention may preferably provide that the lignin naturally present in the plant starting material is used for binding.

[0043] Alternatively, a binder can be added to the mixture or the hydrophobized starting material. Binders known to experts can be used here, for example, natural binders such as clay or loam.

[0044] In order to enable bonding with a binder naturally occurring in the starting material, preferably with lignin, it is preferably provided that the mixture of plant starting material and the at least one metal soap is heated during or subsequently for the purpose of hydrophobization and formation of hydrophobized starting material according to the invention to at least a release temperature, in particular above the release temperature, which causes the release of the natural binder from the plant starting material.

[0045] In all applications where heating above the release temperature is carried out, this is preferably done in such a way that the release is effected without causing thermal degradation of the released binder, in particular lignin. Specifically, the heating does not exceed the release temperature by more than 10%.

[0046] Preferably, the process should be heated to over 120 degrees Celsius, particularly up to a maximum of 170 degrees. This temperature is generally sufficient to release lignin.

[0047] It may be possible to select the temperature to which the material is heated, depending on the moisture content of the plant material, in particular the moisture content which is measured for this purpose, especially because the release temperature may be moisture-dependent.

[0048] The invention can also provide that the starting material, which has already been made hydrophobic by a first heating step according to the invention, is subjected to a further heating step after cooling to a temperature of at least the release temperature, in particular 120 degrees Celsius, particularly in order to achieve a bond with the natural binder, preferably lignin, only in the second heating step, especially during compression. Preferably, the aforementioned temperature restrictions also apply here.

[0049] Preferably, the heating to a temperature of at least the release temperature, in particular 120 degrees Celsius, is carried out during the compression of the hydrophobized starting material or the mixture of plant-based starting material and the at least one metal soap. Thus, during the application of force during compression, the temperature above the release temperature releases the natural binder and directly effects the bonding process. The compression also results in improved distribution of the released binder, particularly the lignin.

[0050] With the invention, the hydrophobized starting material can be integrated into a component, e.g. by joining it with another element or by forming the component itself, e.g. the aforementioned plate or other shaped structure.

[0051] Thus, with a comparatively low density, especially if no or only slight compression takes place, an insulating material can be produced that is hydrophobic and whose insulating effect is due to the naturally occurring cavities in the starting material.

[0052] In a version with a comparatively high density, a comparatively stronger material can be produced, especially when compression is carried out. In this process, it may be possible to reduce the particle size of the starting material and preferably also of the metal soap to less than 1 mm in order to achieve a high density.

[0053] Further properties of the product can be changed by selecting the metal soap.

[0054] For example, in the case of a material to be protected, the ignition behavior or thermal degradation of the material can be slowed down by selecting a metal soap used for hydrophobization with a melting temperature below the ignition temperature of the material.

[0055] This ensures that, in the event of a fire, the melting point of the metal soap is reached before the ignition point of the material being protected. The resulting melting process consumes energy from the fire, thus delaying the heating of the material above its ignition point, at least in time. The process is summarized below using the flowchart, where dashed lines represent an optional step and solid lines represent a mandatory step.

[0056] Figure 1 shows the process. The essential step is mixing plant-based raw material with at least one metal soap. Prior to this, the plant-based raw material, and optionally at least one metal soap, may be ground.

[0057] Furthermore, heating the mixture is mandatory for the process in order to produce the product according to the invention, a hydrophobic starting material.

[0058] Optional steps for the production of a semi-finished or finished product may include bonding and, if necessary, compression, preferably with simultaneous shaping of the desired shape.

Claims

Patent claims 1. A method for hydrophobizing a plant-based starting material, wherein the starting material is treated with a hydrophobizing agent, characterized in that a mixture of the starting material, which is preferably in a dried state, and at least one metal soap as a hydrophobizing agent is produced, and the treatment is carried out by heating the mixture.

2. Method according to claim 1, characterized in that the starting material is crushed before mixing, in particular by chopping or grinding, in particular to a size less than or equal to 10 mm, preferably less than or equal to 5 mm and particularly preferably less than or equal to 0.5 mm, in particular the starting material is brought into a granular or powder form.

3. A method according to any of the preceding claims, characterized in that a metal salt of a saturated or unsaturated fatty acid is used as the metal soap, which has a chain length greater than 0.6, preferably less than 2.8, preferably, wherein the fatty acid is one of the following: stearic acid (C18H36O2), palmitic acid (C16H32O2), lauric acid (C12H24O2), α-linolenic acid (C18H30O2), oleic acid (C18H34O2).

4. Method according to one of the preceding claims, characterized in that the metal soap is selected to contain an ion of a metal from the following list: alkali metals, preferably lithium, or alkaline earth metals, preferably magnesium, calcium or zinc or aluminum.

5. Method according to one of the preceding claims, characterized in that the mixture comprises 80% to 99% starting material and 1% to 20% metal soap, preferably that the mixture comprises 90% to 95% starting material and 5% to 10% metal soap.

6. Method according to one of the preceding claims, characterized in that the mixture is heated above the melting temperature of the at least one metal soap used, in particular the heating does not extend above the pyrolysis temperature of the plant starting material, further preferably the temperature during heating is between 105% and 115% of the melting temperature of the metal soap.

7. Method according to one of the preceding claims, characterized in that a plant-based starting material is used which has natural cavities, in particular pores and / or capillaries, and after heating the internal cavity walls, in particular pore walls and / or capillary walls, are hydrophobized with the metal soap, preferably while avoiding a complete filling of the cavities.

8. A method according to any of the preceding claims, characterized in that the starting material is selected from at least one of the following plant groups: a. a grass-like plant group, in particular Miscanthus spp., Switchgrass spp., Phyllostachys spp. b. a herbaceous plant group, in particular Helianthus spp., Silphium spp., Sida spp. c. a woody plant group, in particular Paulownia spp., Sambucus spp., Picea spp.

9. Method according to one of the preceding claims, characterized in that the starting material is formed by a plant tissue, in particular a plant according to claim 8, preferably which contains parenchymatous tissue.

10. Method according to one of the preceding claims, characterized in that the hydrophobized starting material is processed into a semi-finished or finished product of an insulating or material, in particular by binding and / or pressing the hydrophobized starting material.

11. Method according to one of the preceding claims, characterized in that the hydrophobized starting material is bound with a binder naturally present in the starting material, in particular lignin, in particular bound to form a semi-finished product or finished product, in particular pressed simultaneously, preferably pressed to form a sheet.

12. Use of a hydrophobized starting material produced according to one of the preceding claims as: a. insulating material, in particular by shaping the mixture, b. solid material, in particular by shaping the mixture, preferably during a compression.

Images