Weather-resistant and flame-retardant composite material

Abstract

The present invention relates to a method for producing a composite material using an alkaline binder containing an alkali silicate glass, an organic gelling agent, and SiO 2 particles, and a biological carrier material. This composite material is particularly stable, flame-retardant, and suitable for exterior use.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a composite material, the manufactured composite material, and its use.

Background Art

[0002] Wood particle board is a composite material manufactured from wood chips and a binder under pressure and heat. There are many variations, particularly with regard to the properties of the wood chips, the orientation of the wood chips, and the numerous manufacturing methods using different binder systems, such that wood particle board can be manufactured as a compact material for a wide range of applications and a wide range of products. These include the use of essentially organic binders based on phenolic resins and aminoplast resins, and more recently, those based on polyurethane resins. The disadvantages here are that the resins mentioned may release formaldehyde, which is harmful to health, during the use of the particle board, and that both the wood chips and the binder are essentially organic and thus flammable. To enable the use of such composite materials, for example in the construction field, inorganic additives that produce a flame retardant effect are introduced. These include, in particular, not only borates and phosphates, but also tannins, which react during a fire to form more highly condensed products to protect the surface of the structural material from further ingress of oxygen. An additional oxygen barrier effect is achieved, for example, by the introduction of layered silicate fillers, such as vermiculite. However, in the case of particularly stringent fire protection requirements, the flame retardancy achievable with such composite materials is insufficient to meet the corresponding standards. The use of a foamed matrix (expanded mass) having a heat-insulating foam structure during a fire, using hydroxymethylcellulose, a combination of dicyandiamide and boric acid, and a layer containing ammonium phosphate, also does not result in a satisfactory improvement in the situation. In addition, the release of formaldehyde, particularly from the matrix material, remains an unsolved problem despite all efforts to improve the fire protection properties in these material approaches.

[0003] In addition, inorganic non-combustible binders are employed in the industry. However, binders based on MgCl 2 / MgO / polyethyleneimine or binders containing gypsum lead to boards with low mechanical strength. The other inorganic binder phases in boards containing particles or fibers are cement, but these are also heavy and cannot be directly processed by material removal. In addition, cement as a binder generates a very poor carbon footprint because during the manufacturing process, when the furnace temperature (1400 °C) occurs and as a result of the heat removal of CO 3 from the CaCO 2 precursor, CO 2 is released.

[0004] To make the boards resistant to weathering and further natural influences, water repellents, fungicides or insecticides are still often used. For example, stilbenes, quinones or pyran derivatives are used to improve termite resistance, or potassium chloride, fluosilicic acid, potassium arsenite are used as contact insecticides against Hylotrupes larvae.

[0005] Water glass-based binders are alternatives because they can achieve flame retardancy in combination with weight reduction and a better carbon footprint, but they lack hydrolysis stability and are highly brittle, so they have not been regarded as important for wood particle boards until now.

[0006] According to DIN EN 312, particle boards are classified into various categories (P1: general-purpose particle boards; P2: particle boards for interior fitout including furniture used in dry areas; P3: particle boards for non-load-bearing purposes in wet areas; P4: particle boards for load-bearing purposes in dry areas; P5: particle boards for load-bearing purposes in wet areas; P6: high-durability particle boards for load-bearing purposes in dry areas; P7: high-durability particle boards for load-bearing purposes in wet areas).

[0007] Water glass has generally been used in admixture with, for example, hydrogel-forming organic polymers (such as galactomannan) in order to improve flexibility and ease of handling.

[0008] Halliburton (Patent Document 1) discloses a binder composed of sodium water glass and galactomannan, which is used as an aid for establishing in-situ diversion of liquid flow in rock formations. There is no description regarding its use for wood particle boards.

[0009] Industrieverband Brandschutz (Patent Document 2) describes a transparent fireproof composition for the production of fireproof building materials and for coating building materials and components of constructed structures, which is made from sodium water glass and an organic binder (such as galactomannan) and has a firm consistency. For this purpose, water glass is mixed with a gel-forming acid (such as citric acid, B(OH) 3 , H 3 PO 4 ) and water to form a hydrogel, further mixed with a preservative (Cu(II) salt), and solidified together with the organic binder to form a transparent solid fireproof composition. The gel-forming acid causes acceleration of the reaction, which contributes to the transparency of the claimed reaction product, but is unsuitable for the production of wood particle boards.

[0010] Seamans (Patent Document 3) describes a flame retardant composition composed of sodium water glass, gum arabic, and an epoxy resin or latex. By combining this composition with cellulose fibers, a board-shaped product can be manufactured by a press molding method. The addition according to the proportion of up to 20% of the epoxy resin or latex helps to improve the moisture resistance of the binder composition.

[0011] The application (Patent Document 4) describes a flexible fireproof composition containing an inorganic gel former and a hydrogel-forming biopolymer (= galactomannan). The use of galactomannan helps to achieve dimensional stability and transportability by forming an organic skeletal structure that has a stabilizing effect on the inorganic gel former. The fireproof composition is processed by casting, rolling, or calendering and is used as an intermediate layer between two window glasses. Since the ends of the window glasses are sealed, the moisture resistance of the composition is not particularly required here. The described composition lacks moisture resistance, so the resulting workpiece is not stable against weathering and thus cannot be actually used as a binder for manufacturing wood particle boards used in the construction field.

[0012] Also, there is a need for a weather-resistant and fire-resistant formaldehyde-free composite material, especially wood particle boards, that can be obtained at least partially from local resources and has a low CO 2 footprint. In addition, the composite material needs to be resistant to insects such as termites.

[0013] Furthermore, the manufacturing needs to be possible by simple means.

Prior Art Documents

Patent Documents

[0014]

Patent Document 1

Patent Document 2

Patent Document 3

[0015] An object of the present invention is to provide a method for producing a composite material having weather resistance, preferably fire resistance, and further to provide the composite material and its use. [Means for Solving the Problems]

[0016] The above object is achieved by an invention having the features of the independent claims. Advantageous developments of these inventions are characterized in the dependent claims. The language in all claims forms part of this specification by reference. These inventions include all executable combinations, in particular all combinations of the mentioned independent and / or dependent claims.

[0017] The above object is achieved by a method for producing a composite material including the following steps: a) preparing an alkaline composition containing at least one alkali metal silicate water glass and at least one organic gel former; b) adding at least one type of SiO 2 particles; c) combining the composition with at least one biological carrier material such as fibers, cuttings or mats from a biological source; d) compressing the resulting composite material in a mold under pressure and high temperature; e) drying the composite material after demolding to obtain the composite material.

[0018] Hereinafter, the individual steps of the method will be described in detail. These steps do not necessarily have to be performed in a specific order, and the method outlined below may also include additional steps not specified.

[0019] An alkaline composition containing at least one alkali metal silicate water glass and at least one organic gel former is prepared.

[0020] The alkali metal silicate water glass is preferably sodium silicate, potassium silicate and / or lithium silicate water glass, more preferably sodium silicate and / or potassium silicate water glass, and even more preferably potassium silicate water glass.

[0021] The water glass is preferably a water glass with high concentration, high viscosity and high solid content. A water glass having a solid content of more than 40% by weight, preferably 40% to 70% by weight, particularly 40% to 60% by weight is preferred.

[0022] A further characteristic of the water glass is the molar ratio of SiO 2 in the water glass to the alkali metal oxide (M 2 O). This molar SiO 2 :M 2 O ratio is referred to as the modulus. The water glass preferably has a molar SiO 2 / M 2 O ratio (modulus) of 0.8 to 4. The water glass is dissolved in the composition. The water glass used is preferably liquid water glass.

[0023] If necessary, it is preferred to add only water as a solvent to the composition.

[0024] The composition is an alkaline composition. Its pH is preferably greater than 12, particularly greater than 13.

[0025] The composition preferably contains at least one alkali metal hydroxide, preferably LiOH, KOH and / or NaOH, preferably KOH and / or NaOH, and even more preferably KOH. The alkali metal hydroxide and the alkali metal silicate water glass preferably have the same alkali metal, such as potassium silicate water glass and KOH. The alkali metal hydroxide activates SiO 2 particles, particularly crushed sand.

[0026] The composition also contains at least one organic gel former. The organic gel former is preferably a polysaccharide and may be chemically modified.

[0027] Suitable polysaccharides are preferably base-stable.

[0028] The organic gel former is preferably selected from xanthan, gum arabic, guaran, galactomannan or mixtures thereof, and the gel former may be chemically modified. Galactomannan is preferred. The ratio of galactose to mannose can be 1:1 to 1:5, preferably 1:2.

[0029] Examples of chemical modifications are hydroxyethyl groups, hydroxypropyl groups, carboxyl groups, carboxyalkyl ether groups (such as carboxymethyl ether), and combinations of different chemical modifications in one polysaccharide.

[0030] In a preferred embodiment of the present invention, the alkali metal water glass and the alkali metal hydroxide are first added together and then the organic gel former is added.

[0031] It is preferred to use water as the solvent in the composition. Water can be added to adjust the solids content and / or viscosity of the composition, or since water is defined by the water glass solution, no additional solvent is added.

[0032] It is preferred to stir the composition for at least 3 hours, preferably at least 10 hours, more preferably at least 20 hours. 3 hours to 96 hours is preferred, 10 hours to 96 hours, particularly 20 hours to 48 hours is particularly preferred.

[0033] In a preferred embodiment, the stirring is carried out at a temperature of 10°C to 40°C, particularly 15°C to 25°C. This is preferably at ambient temperature.

[0034] Stirring in a closed container is preferred.

[0035] The resulting composition (precursor composition) is storable and can be stored until further processing. Gel former swelling may occur during storage. However, the composition is still activatable and suitable for processing. The composition is preferably storable for at least 6 months, particularly at least 1 year.

[0036] At least one kind of SiO 2 particles are added to the composition. These are preferably SiO 2 particles containing particles in the micrometer range as the main component. SiO 2 particles having an average particle size of 0.05 μm to 70 μm, preferably 0.2 μm to 30 μm are preferred.

[0037] Particles having a particle size distribution with d 90 less than 30 μm are preferred. The particles preferably have a particle size distribution with d 90 less than 30 μm and d 10 less than 6 μm. Particles having a particle size distribution with d 90 from 2 μm to 30 μm and d 10 from 0.1 μm to 6 μm, particularly particles having a particle size distribution with d 90 from 10 μm to 30 μm and d 10 from 0.2 μm to 2 μm are particularly preferred. More preferably, the particles have d 90 from 2 μm to 30 μm, d 50 from 1 μm to 8 μm and d 10 from 0.1 μm to 6 μm, preferably having d 90 from 10 μm to 30 μm, d 50 from 2 μm to 5 μm and d 10 from 0.2 μm to 2 μm.

[0038] The distribution is determined by laser diffraction as a powder and an aqueous dispersion, and determination in the aqueous dispersion is preferred.

[0039] In a preferred embodiment of the present invention, the particles include ground sand, preferably ground sand ground to the above particle size distribution.

[0040] The specific surface area of the particles is preferably 1 m 2 / g to 5 m 2 / g, particularly 1.5 m 2 / g to 3.5 m 2 / g (determined by BET).

[0041] The SiO 2 content is preferably more than 90% by weight, particularly more than 95% by weight, and very particularly more than 99% by weight (confirmed by ICP - OES (after microwave digestion, using Ultima2 from Horiba Jobin Yvon, decomposing in 1 ml of 65% HNO 3 , 3 ml of 35% HCl, 1 ml of 50% HF and 2 ml of ultrapure water. Analyze the mineral content of the hydrolyzate by ICP - OES. Perform quantitative detection using a standard calibration curve)).

[0042] The resulting composition is preferably homogenized with stirring.

[0043] In one embodiment of the present invention, fumed silica is added alternatively or additionally to the above - mentioned particles. The fumed silica may have a smaller particle distribution. For example, the fumed silica may contain particles having a size of less than 1 μm. An example of fumed silica is, for example, Aerosil having a particle size of 200 nm to 300 nm. The fumed silica can shorten the drying time until complete water stability is achieved. However, the pot life of the activated composition usually becomes shorter.

[0044] It is also possible to add further inorganic substances, for example up to 10% by weight, but this is not preferred. An inorganic substance with an SiO 2 proportion exceeding 50% by weight is preferred. These examples are layered silicates such as quartz, mica, etc., and wollastonite. Further examples are shown in Table 1.

[0045] It is preferred to process the resulting activated composition into a paste form. The viscosity can be adjusted according to the desired processing by adding a solvent.

[0046] The composition preferably has a pot life of up to 48 hours. The pot life can be adjusted, in particular, by the size distribution of the SiO 2 particles. For storage below 10 °C or in a sealed container, the pot life can be extended up to 8 days.

[0047] In a preferred embodiment, the weight ratio of alkali metal water glass to SiO 2 particles is from 30:70 to 70:30, preferably from 40:60 to 60:40.

[0048] In a preferred embodiment of the present invention, the activating composition comprises 35 wt% to 60 wt% of alkali metal water glass, 1.5 wt% to 5 wt% of at least one alkali metal hydroxide, 0.3 wt% to 2.5 wt% of at least one gelling agent, and 30 wt% to 60 wt% of at least one kind of SiO 2 particles. In a particularly preferred embodiment of the present invention, the activating composition comprises 40 wt% to 55 wt% of alkali metal water glass, 1.5 wt% to 5 wt% of at least one alkali metal hydroxide, 0.3 wt% to 1.1 wt% of at least one gelling agent, and 30 wt% to 55 wt% of at least one kind of SiO 2 particles.

[0049] An example of the composition is, for example, 49.3 wt% of alkali metal water glass, 4 wt% of at least one alkali metal hydroxide, 0.8 wt% of a gelling agent, and 45.9 wt% of ground sand.

[0050] The weight percentages are preferably based on the weight of the alkali metal hydroxide. A proportion of at least 75 wt%, in particular at least 80 wt%, most preferably at least 85 wt% of the alkali metal hydroxide based on weight is preferred. For example, potassium hydroxide is usually available in solid form with a KOH content of 85 wt% and 15 wt% water. M 2 O content or K 2In the calculation of the O content, only MOH or KOH is considered.

[0051] Surprisingly, the combination of the alkaline medium of the binder with SiO 2 particles and water glass has been found to form a particularly stable binder. In particular, SiO on the μ scale such as ground sand 2 particles are presumed to function as reactive fillers because the surface of the particles is partially dissolved in the alkaline medium and is partially converted to alkali metal silicate on the surface. Since its filler properties are maintained especially in a multimodal and / or wide size distribution, compression and hardening result in the closest packing of the partially dissolved particles. Hardening, in particular, raises the SiO 2 / M 2 O modulus to a value exceeding especially 8, in particular a value exceeding 9, and is assisted by additionally charging SiO 2 through the particles. Good bonding enables the production of composite materials, especially wood materials, having very good mechanical properties and water resistance or weather resistance.

[0052] The precursor composition and the activation composition preferably do not contain any further crosslinking agents such as boric acid or refractory components such as aluminum salts. It is preferred not to add solvents other than water. In addition, the precursor composition and the composition do not contain any polyols such as glycol, glycerol or polyethylene glycol diglycidyl ether except for the gel former. Therefore, it is preferred not to use such organic crosslinking agents for the polysaccharide gel.

[0053] The activation composition preferably has an SiO 2 / M 2 O modulus exceeding 8, in particular exceeding 9. An SiO of 8 to 16, preferably 9 to 14, very particularly 9 to 10 2 / K 2 O modulus is preferred.

[0054] The composition does not contain any further hydroxides, especially Ca(OH) 2It is preferably free of alkaline earth metal hydroxides such as etc.

[0055] The composition preferably does not contain any organosilane or modified colloidal nanoparticles.

[0056] The activation composition may optionally contain additives that facilitate processing, such as thixotropic additives for dilution up to 2 wt%, especially up to 1 wt%, when the composition is sprayed. An example of such an additive is microfibrillated cellulose (MFC).

[0057] The activation composition is combined with or contacted with a biological carrier material such as fibers, cuttings or mats from a biological source. This can be achieved by impregnation, dipping, coating, spray coating or other application methods. It is also possible to apply multiple layers of wood fibers and / or wood cuttings, as well as the activation composition.

[0058] The biological carrier material is preferably obtained from renewable raw materials.

[0059] Biological carrier materials such as fibers, cuttings or mats from a biological source can be obtained from any plant or tree suitable for composite materials.

[0060] The biological filler is preferably obtained from rice husks, rice glumes, reeds, sisal, hemp, cotton, kenaf, bamboo, flax, nipa palm or coconut palm, wood and / or sugarcane.

[0061] Examples of trees are conifers such as pine, spruce, fir; beech, oak, pine, walnut, acacia, etc.

[0062] Local sources are particularly preferred, which is CO 2 Also preferred with respect to the footprint.

[0063] The carrier material, especially wood, does not need to be dried.

[0064] The carrier material is preferably in the form of cuttings or mats.

[0065] The biological carrier material preferably has a proportion of SiO 2 in excess of 1% by weight, in particular in excess of 2% by weight, which aids the binding of the activation composition to the carrier material. This applies, for example, to acacia or rice straw having a content of more than 5% by weight.

[0066] The lignocellulose and / or wood cuttings are preferably produced by chipping or hammer-milling of sawn timber or wood waste from the sawmill industry. For the production of particleboard, the material is usually screened by evaluating the properties of each screen fraction according to the mesh size.

[0067] It is known to those skilled in the art in the production of particleboard that the properties and appearance of the composite material can be influenced by the choice of size distribution. For example, it is also possible to apply various layers containing fibres and / or cuttings of different sizes in order to obtain a finer outer layer.

[0068] Fibres and / or cuttings, in particular lignocellulose and / or wood cuttings, from at least one screen fraction having a range selected from the range of 0.5 mm to 10 mm are preferred. Preferably, the screen fraction has a range of more than 1.4 mm to 4 mm. For finer layers, such as the outer layer, it is possible to use screen fractions of, for example, 1 mm to 2 mm or 1 mm to 1.4 mm.

[0069] The combination is preferably carried out in a corresponding mould depending on the shape of the composite material to be obtained.

[0070] The ratio of the composition (binder) to the biological carrier material can be selected according to the composite material to be obtained. For example, it is also possible to use different biological carrier materials, such as different screen fractions, in the composite material in order to obtain different surface structures.

[0071] The ratio of the solid in the composition to the biological carrier material can be freely selected. This can be selected according to the material to be manufactured. It may also depend on the surface and / or density of the carrier material and / or SiO 2 particles. In the case of high density, less binder is required. Also, in the case of a biological carrier material with a high surface area, more binder is required for wetting. It is preferable to use at least the same amount of binder as that required for wetting the surface of the biological carrier material.

[0072] Therefore, this ratio can be selected from a wide range. It is preferable that the mass ratio of the solid in the binder to the carrier material is 1:10 to 10:1 by weight, preferably 1:5 to 5:1, and more preferably 20:80 to 80:16. In terms of the relationship with mass, this ratio generally corresponds to the ratio of the binder to the carrier material in the composite material.

[0073] A weight ratio of 0.5:1 to 5:1 is preferable.

[0074] For example, for a compact board, a ratio of 1:1 to 4:1, particularly 2.89:1 to 3.29:1, based on the mass of the solid in the binder to the biological carrier material, is preferable.

[0075] For example, for a lightweight construction board, a ratio of 0.3:1 to 1:1, particularly 0.4:1 to 1:1, based on the mass of the solid in the binder to the biological carrier material, is preferable.

[0076] Depending on the biological carrier material, it may be advantageous to age the resulting composite material for up to 200 hours, preferably up to 180 hours, particularly up to 150 hours, before compression. This can be done in a stationary state or with stirring. In this way, the materials can be better bonded to each other.

[0077] The resulting composite material is compressed in a mold under pressure and high temperature. This may be the mold in which the composite material was combined in the previous step.

[0078] Here, a temperature of 60°C to 100°C, more preferably 80°C to 90°C, is preferred.

[0079] Compress the composite material until its strength becomes sufficient. This is, for example, after at least 4 hours, especially after 5 hours to 30 hours.

[0080] The required time and temperature can be selected for each application. Generally, the higher the temperature, the shorter the compression time.

[0081] The pressure used can be adjusted appropriately. The pressure is usually 15 bar to 50 bar.

[0082] It may be advantageous to use an activation mixture stored for at least 48 hours. Due to the increase in viscosity, the amount of binder extruded decreases.

[0083] Demold the obtained composite material and preferably dry it under the action of a CO 2 source to obtain a composite material.

[0084] These are preferably conditions for carbonating the composite material. The uptake of CO 2 results in further hardening of the composite material. Carbonation in less than 240 hours, especially less than 120 hours, very especially less than 48 hours, is preferred.

[0085] These are usually conditions with a higher CO 2 content compared to the atmosphere.

[0086] This can be done, for example, by storing the sample in a glycerol carbonate or propylene carbonate solution. In an alkaline medium, these compounds release CO 2 which binds to the excess hydroxides in the composite material, such as KOH. This can also be done at high temperatures. Then, the sample can be washed and dried.

[0087] Alternatively, the composite material can also be stored with dry ice, for example, in an environmentally controlled chamber at 20 °C and 65% relative humidity.

[0088] Carbonation is also possible by storage in the natural atmosphere. Storage for at least 30 days, preferably at least 50 days, is preferred. Here, storage at ambient temperature, particularly at room temperature of 20 °C to 30 °C, is preferred.

[0089] Drying can be carried out at high temperatures, for example, 60 °C to 100 °C, particularly 70 °C to 90 °C.

[0090] It is also possible to provide the composite material with further layers such as a decorative layer, a coating layer, a varnish, etc.

[0091] The obtained composite material of the present invention has many advantageous properties.

[0092] The water glass-based binder used cures without cracks. The precursor composition has good storage stability before use. This simplifies handling and transportation. The pot life of the activating composition can be controlled.

[0093] CO 2 The footprint is reduced to a quarter of that of cement.

[0094] Despite the use of water glass, high stability against weathering and hydrolysis is achieved.

[0095] The use of water glass means that the composite material is essentially flame-retardant.

[0096] The composite material is suitable for the highest mechanical requirements for wood materials, particularly wood particle boards, in the construction field (indoor and outdoor).

[0097] It also has excellent resistance to termites.

[0098] Since it is possible to use local resources as a source of wood or biological carrier materials, the composite material can be manufactured in various ways locally. SiO 2 It is also possible to obtain the particles from local sand sources. In this way, local production of wood materials can be realized in a simple manner.

[0099] The composite material does not contain formaldehyde. Also, it is preferable not to use cement admixtures such as Ca(OH) 2 etc.

[0100] In the drying process, CO 2 may even be absorbed.

[0101] Therefore, the present invention also relates to the composite material manufactured by the above method.

[0102] The composite material can have many types of shapes.

[0103] This is suitable for, for example, particle board, furniture, doors, chairs, tables, interior materials, worktops, cabinets, sideboards, floorboards, deck boards, wall elements, ceiling elements or roof elements.

[0104] The composite material preferably contains wood fibers and / or wood cuttings from acacia.

[0105] The present invention also relates to the precursor composition obtained by step a) of the above method.

[0106] The present invention also relates to the use of the precursor composition for the manufacture of the composite material.

[0107] Further details and features will become apparent from the following description of the preferred embodiments in conjunction with the dependent claims. Here, each feature can be implemented alone or in combination with some of them. The means for achieving the object are not limited to the embodiments.

[0108] The embodiments are schematically shown in the figures. The same reference signs in the individual figures denote the same elements, or elements having the same function, or elements corresponding to each other in terms of function. Each figure shows the following.

Brief Description of the Drawings

[0109]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0110] Manufacture of binder: Example 1a: Precursor composition (precursor NMC4 210913) 13.15 g of potassium hydroxide (85 wt%) is dissolved with stirring in 161.73 g of van Baerle's potassium water glass (SiO 2 / K 2 O modulus: 2.93:1; density 1.42 g / ml, viscosity 40 mPas to 50 mPas, about 41.3 wt% solids). After cooling the solution to room temperature, 2.63 g of guar (galactomannan with a galactose / mannose ratio of 1:2) is added little by little with vigorous stirring. When the addition of guar is complete, the viscosity of the solution slightly increases. To further swell the guar, the mixture is stirred at low speed at room temperature for at least another 24 hours. In this form, the binder precursor can be stored indefinitely.

[0111] Example 1b: Activation (NMC4 210913) First, 142.93 g of crushed sand (size distribution: for example, d(10)=0.547 μm; d(50)=3.793 μm; d(90)=19.642 μm, and specific surface area of about 4.01 m 2(g) is homogeneously dispersed in 177.51 g of a high-viscosity binder precursor using a dissolver disk. Then, 7.6 g of fumed silica (primary particle size distribution of about 200 nm to 300 nm) is further homogeneously mixed in little by little. 328.04 g of a milky white binder paste is obtained (solid content: about 58.35%). The pot life of the activated binder is about 12 hours.

[0112] The size distribution is determined by laser diffraction. For this purpose, a Mastersizer 2000 from Malvern Panalytics was used. The particle size was determined by laser diffraction for both wet dispersion and dry dispersion. For automatic dry dispersion, a Scirocco 2000 unit was used. For wet dispersion, an automatic Hydro 2000 S wet dispersion unit was used. Fine particles up to about 200 nm were detected in dry dispersion, while in the wet method, fine particles exceeding 350 nm were obtained, and better reproducibility was obtained over 3 measurements / samples. For the size distribution of the dry method, values of 0.547 μm (d10), 3.793 μm (d50), and 19.642 μm (d90) were obtained. The values confirmed by the wet method were 0.951 μm (d10), 3.722 (d50), and 19.982 (d90). The aqueous dispersion gives more homogeneous data, and the dispersion of sub-μ-sized particles clearly gives low results due to the formation of aggregates in the aqueous solution. The preferred values are based on the wet method.

[0113] Table 2 lists various binder compositions. Betol is a further water glass. Woellner:Betol K57M: modulus of about 1:1; density 1.65 g / ml; solids: about 52%; viscosity about 60 mPas. MFC is used as a thixotropic additive during dilution. In the case of KOH, the weight is based on 85 wt% KOH content of KOH.

[0114] Example 1c: Manufacture of a composite board based on wood cuttings Vigorously mix 328.04 g of binder paste (NMC4 210913) with 160 g of acacia cuttings (fraction over 1.4 mm to less than 4 mm). After about 30 minutes, homogeneously introduce the mixture into a non-stick coated press mold. With this press mold, a board with dimensions 20×20×1 cm 3 can be manufactured. The surface can be further improved by applying a binder-wood cuttings blend containing a finer screen fraction of shredded biomass. An exemplary composition is as follows: Homogeneously blend 72 g of activated binder paste with 24.4 g of wood cuttings fraction of 1 mm to 1.4 mm and 12 g of wood cuttings fraction of 500 μm to 1 mm, and homogeneously apply it to the surface of a coarser wood cuttings-binder blend previously introduced into the press mold. In a hot press, compress the binder-wood cuttings blend and cure it at a temperature of 80 °C for 20 hours under reduced pressure. Then, dry the demolded board in a drying cabinet at 70 °C to 90 °C until it reaches a constant weight. The ratio of the weight of the binder solids to the weight of the acacia cuttings is 1.2:1.

[0115] Carbonation is carried out after the composite board reaches a constant weight: a) For 3 days in a climate-controlled cabinet at 20 °C and relative humidity 65% while sparging with CO 2 using dry ice. For this purpose, replenish the dry ice after 8 hours, 24 hours, 32 hours, 48 hours, and 56 hours. 5 g of dry ice is introduced at 8 hours and correspondingly 10 g at 16 hours. b) Immerse in propylene carbonate (CO 2 source) and store in a drying cabinet at 80 °C for 24 hours. Then, store the composite board in deionized water at room temperature for about 10 seconds, twice. Dry it overnight at 80 °C in the drying cabinet. c) Instead of propylene carbonate in example b), use glycerol carbonate (CO 2 source).

[0116] Figure 1 shows the dependence of mechanical properties on the binder / fiber weight ratio (where the binder here is the solid of binder deformation NMC4 210121, and the aging of the precursor = 1 d (= 1 day elapsed)). Subsequently, the precursor was activated with pulverized sand and acacia fibers were incorporated. After 2 hours, molding was carried out for 20 hours in a hot press at 80 °C and a pressure of 25 bar. Following demolding, it was further cured for 24 hours in a drying cabinet at 80 °C. The flexural strength and transverse tensile strength were confirmed after natural aging for 50 to 55 days.

[0117] Example 2a: NMC4 210121 26.3 g of potassium hydroxide (85 wt%) is dissolved with stirring in 323.46 g of van Baerle's potassium water glass (SiO 2 / K 2 O modulus: 2.93:1; density 1.42 g / ml, viscosity 40 mPas - 50 mPas, about 41.3 wt% solids). After cooling the solution to room temperature, 5.26 g of guar (galactomannan with a galactose / mannose ratio of 1:2) is added little by little with vigorous stirring. When the addition of guar is complete, the solution shows a slight increase in viscosity. To further swell the guar, the mixture is stirred at low speed for at least another 24 hours at room temperature. In this form, the binder precursor can be stored indefinitely.

[0118] 301.06 g of pulverized sand is homogeneously incorporated into 355.02 g of the high-viscosity binder precursor using a dissolver disk. 656.08 g of a cream-colored binder paste (NMC4 210121) is obtained (solid content: about 58.35%).

[0119] Example 2b: 140.6 g of acacia fibers are homogeneously blended with 656.08 g of binder (NMC4 210121). After standing for 2 hours, the resulting binder / fiber mixture is placed in a press mold (cavity: 200×200×20 mm 3) Introduce it into , compress it into a board with a thickness of 1 cm using a hot press at 80 °C and a pressure of 25 bar, and pre-cure it for 20 hours under these conditions. Final curing is carried out at 80 °C for 24 hours in a drying cabinet.

[0120] Example 3: Hemp woven fabric composite: Mix 98.2 g of potassium water glass (van Baerle) with 8.6 g of KOH while stirring, and cool in an ice bath. Then, add 1.6 g of carboxymethylated guar (Ranie Chemie Produktions- und Vertriebs-GmbH: RAGUM AD type) to the mixture little by little. After the addition is complete, remove the ice bath and stir the mixture at room temperature overnight.

[0121] After about 20 hours, add 89.2 g of silica sol (Levasil 50 / 50), and then 36.6 g of crushed sand to the precursor while stirring for activation. 12.31 of SiO 2 / K 2 An activation composition (NMC4-based) with an O modulus of and a solids content of about 46.4% is obtained as 234.2 g. Then, add the binder by hand to 21.6 g of hemp woven fabric (basis weight 1000 g / m 2 ). An appropriate excess of binder is required to homogeneously disperse the binder in the hemp woven fabric with sponge-like absorbency. Use all of the pre-prepared binder.

[0122] Next, precondition the woven fabric impregnated with the binder in a furnace preheated to 40 °C for 1 hour. Then, pre-cure the woven fabric in a hot press at 85 °C. Excess binder is extruded during this process. To achieve uniform evaporation of the residual water, further cure the pre-cured woven fabric under reduced pressure in a hot press at 80 °C for 16 hours between perforated sheets.

[0123] The weight of the cured hemp composite is 92.65 g. This corresponds to a binder - hemp woven fabric ratio of 3.29 parts by weight of cured binder per 1 part by weight of hemp woven fabric.

[0124] Example 4: Lightweight construction board Spray application of binder to fibers and subsequent production of composite material: 238 g of fibers finely dispersed in the tank and in the thin layer are wetted with binder NMC4 - MFC (Table 2) using a spray gun (SATAjet) at a spray pressure of 1.0 bar. Once the fibers are uniformly and finely wetted, the layer of fibers is rotated 180° and sprayed again until wetting by the binder is clearly visible.

[0125] The total weight of the wet fibers is 442.6 g. Put 220.4 g in another container.

[0126] The remaining 222.22 g are again finely dispersed in the tank and sprayed with binder from both sides once more. The subsequent wet weight is 276.8 g. This binder - fiber mixture is also put in another container until further processed.

[0127] For the production of the composite board, the two fiber - binder mixtures are each introduced into a press mold (20×20×about 2 cm 3 ) lined with a baking sheet, compressed by hot pressing to a layer thickness of 1 cm at a pressure of 30 bar, and then pre - cured at 85°C. After 1.5 hours, the composite is demolded and further cured at 80°C for 40 hours in a drying cabinet inserted into a curing frame (hardening). Boards with a total weight of 169.29 g for Sheet 1 and 204.59 g for Sheet 2 are obtained.

[0128] Carbonation was carried out by storage in air and absorption of CO 2 from the air.

[0129] The weight ratio of fiber to binder (cured) is as follows: Sheet 1: Fiber about 2.33 to binder 1 Sheet 2: Fiber about 1.4 to binder 1

[0130] The sheets were tested by the following method: Bending test: (EN 310, classification EN 312), modulus of elasticity, maximum tensile stress Transverse tensile strength: (EN 319, classification EN 312) Tests after drying and boiling EN 1087-1 (90 minutes from 25°C to 100°C, 120 minutes at 100°C) Water retention: (EN 317: thickness swelling, EN 321: moisture resistance by cycle test, EN 1087-1: boiling test)

[0131] For some test specimens, a modulus of elasticity in the range of 2.2 GPa (P2 classification according to EN 312) to 4.4 GPa (P7) was achieved in the bending test. The bending strength was in the range of 11 MPa (P1) to 20 MPa (P6).

[0132] In the transverse tensile test according to EN 319, a strength in the range of 1.2 MPa to 3.6 MPa (P7) was achieved. Even after the boiling test in water (90 minutes from 25°C to 100°C; 120 minutes at 100°C), a strength in the range of 0.15 MPa to 0.35 MPa was still measured.

[0133] Also, the samples were stored in water at 20°C for 24 hours. The sheets of the composite material of the present invention containing acacia cuttings showed only an increase in weight of 0% to 4% and an increase in thickness of 0% to 3%.

[0134] This composite material uses water glass and SiO 2 particles and thus has good fire resistance. Since a glass foam is formed at high temperatures, heat insulation is provided and the combustion of the material is prevented. The manufactured sheets could be directly exposed to a flame at a temperature exceeding 1000°C for 1 hour without ignition or perforation of the board.

[0135] When the obtained composite material was stored in an area within the movement radius of termites close to a termite nest, no signs of termite invasion were shown even after 6 months.

[0136] Figure 2 shows the dependence of the elastic modulus and the three-point bending strength on the aging of the binder / fiber mixture. The binder precursor NMC4 that had elapsed 23 days was used for production. After aging the binder / fiber mixture for 5 to 6 days, the bending strength and the elastic modulus reach their maximum (production parameters: pressing at 40 bar and 80 °C for 1.5 hours; 75.1 wt% based on the solid content of the binder, NMC4 as the precursor).

[0137] Table 3 shows the dependence of the properties of the composite material on the aging of the storable binder precursor at the number of days (d) of 1d, 4d, 7d, 15d, 16d, 21d, 23d. MFC means the additization of microfibrillated cellulose.

[0138] The storage time of the produced composite material was 1.5 to 2 months at room temperature.

[0139] The test pieces were also subjected to accelerated carbonation according to at least one of the above deformations.

[0140] An expansion test was carried out after 2 to 3 months, and then after drying and adjusting to a constant weight, a boiling test was carried out.

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Claims

1. A method for manufacturing composite materials, a) A step of preparing an alkaline composition comprising at least one alkali metal silicate water glass and at least one organic gel-forming agent, b) At least one type of SiO ２ The process of adding particles, c) A step of combining the composition with at least one biological carrier material, d) A step of compressing the resulting composite material in a mold under pressure and high temperature, e) A step of drying the composite material after demolding to obtain a composite material, Methods that include...

2. The method according to claim 1, characterized in that the organic gel-forming agent is a polysaccharide.

3. The method according to claim 1 or 2, characterized in that the alkaline composition comprises at least one alkali metal hydroxide.

4. The method according to claim 1 or 2, characterized in that the organic gel-forming agent is selected from xanthan gum, gum arabic, gualan, galactomannan, or a mixture thereof, and the gel-forming agent may be chemically modified.

5. The SiO ２ The method according to claim 1 or 2, characterized in that the particles include crushed sand.

6. A composite material obtained by the method described in claim 1 or 2.

7. A precursor composition obtained from step a) of the method according to claim 1 or 2.

8. The precursor composition according to claim 7 for the production of a composite material.

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