Silicate precursor for sol-gel process, process for preparation thereof and use thereof

Abstract

The invention relates to alkali metal hydrosilicates and to a method for producing same by mixing a particulate silica feedstock comprising at least 70% amorphous SiO2 with a dry particulate alkali metal hydroxide and further adding water, and to the use thereof.

Description

Technical Field

[0001] This invention relates to alkali metal hydrosilicates and a method for producing them, which involves mixing a particulate silica raw material containing at least 70% amorphous SiO2 with a dried particulate alkali metal hydroxide, and then adding water. Background Technology

[0002] The alkali metal hydrosilicates of the present invention refer to intermediates, more specifically precursors, of hydrosilicate gels and / or corresponding solid silicates produced by a sol-gel method. The properties of these silicate materials depend on the composition of the precursor and the conditions of the sol-gel method, and they possess valuable properties such as adhesiveness, endothermic phase transition capacity, water deposition capacity, and cellulose silicification capacity, thus making them suitable as fire-retardant materials, materials for preventing thermal runaway, and raw materials for the production of cellulose-based composite materials. As used herein, the term "hydrosilicate" also includes aluminum hydrosilicates.

[0003] As mentioned above, alkali metal hydrosilicates are precursors for sol-gel processes, as defined in Chapter 11, “Definitions of Terms Related to the Structure and Processing of Sols, Gels, Networks and Inorganic-Organic Hybrids,” on pages 211-236 of Compendium of Polymer Terminology and Nomenclature IUPAC Recommendations 2008 (edited by Richard G. Jones et al., Royal Society of Chemistry Press, 2009, ISBN: 978-0-85404-491-7).

[0004] WO 2021 / 248173 A2 describes a method for preparing a colloidal aqueous dispersion of alkali metal hydrosilicates in the properties of fire-resistant systems, comprising adding pulverized coarse silica material and granular alkali metal hydroxide to a reactor, adding water to the reactor, and mixing the components under spontaneous heating. The resulting colloidal aqueous dispersion of alkali metal hydrosilicates can be cured under ambient conditions to obtain a hard alkali metal hydrosilicate gel, and must be stored in an airtight package, preferably vacuum-packed.

[0005] There is still a need for an alkali metal hydrosilicate with improved properties, such as fire-retardant properties due to high water content, and handling properties, especially without curing or hardening after storage for at least 28 days at standard ambient temperature and pressure (SATP, 25 °C, 100,000 kPa / 1 bar). Summary of the Invention

[0006] This objective is achieved by the alkali metal hydrosilicate according to the invention and the method for preparing it.

[0007] The method according to the present invention includes the following steps: a) Provide a particulate silica raw material comprising at least 70% amorphous SiO2 and a dry particulate alkali metal hydroxide, and optionally adjust the moisture content of the silica raw material to at least about 70 wt% and not more than about 84.5 wt%; b) At a specific energy input of about 200 kJ / kg to 750 kJ / kg, the granular silica raw material and the dry granular alkali metal hydroxide are mixed in a ratio of 1 part by weight of alkali metal hydroxide and 5.25 to 10.5 parts by weight of silica raw material, preferably in a stirrer or mixer, at a rotation speed of about 1000 to about 4000 rpm.

[0008] c) Add water to achieve a total weight ratio of 1 part by weight of dry solids to 2.5 to 4.8 parts by weight of water, preferably under the mixing conditions of step b), to obtain a viscous product, and optionally adjust the amount of water based on the moisture content of the silica raw material used.

[0009] Suitable silica raw materials for obtaining the alkali metal hydrosilicates of the present invention are natural or artificial materials containing not less than 70 wt% amorphous SiO2 (see, for example, WO 2009 / 105051 A1 and WO 00 / 46277 A2). Natural materials are typically selected from sedimentary rocks, such as diatomite, kieselguhrs, tripoli, planner, spongiolite, radiolarians, opals, etc. (e.g., Ivanenko VN, Building materials and products from siliceous rocks, Kiev, “BUDIVELNIK” Publishing House, 1978, p. 5). Artificial materials are byproducts of amorphous silica, including fused silica, silica fume, microsilica, and other technical types of amorphous silica. One or more silica raw materials may be used. For processing purposes, the starting material is used in crushed and / or milled form (i.e., granular form). Preferably, the average particle size is equal to or less than 0.5 μm, more preferably 50-150 µm. Preferably, the silica raw material is pulverized to result in a specific surface area of ​​0.05 m². 2 / g to 0.5 m 2 Particle size within the range of / g. The manufacturing method does not require further crushing, but is covered by this invention. In the foregoing, the starting silica material in particulate form is also referred to as "siliceous sand".

[0010] Preferably, the silica raw material is selected from diatomaceous earth and amorphous silica byproducts.

[0011] A more preferred silica raw material is diatomaceous earth (type 1) with the following composition:

[0012] Or diatomaceous earth composed of the following (type 2):

[0013] Or, amorphous silica byproducts (microsilica powder) produced from ferroalloys with the following composition:

[0014] The moisture content of the silica raw material used is preferably at least about 70% wt and not more than about 81.5 wt%, more preferably from about 71 wt% to about 80 wt%, even more preferably from about 71.5 wt% to about 79.5 wt%, specifically from about 71.9 wt% to about 78.0 wt%. Preferably, the moisture content of the silica raw material used is determined before feeding and adjusted accordingly by drying or adding water. Because water is added to the reaction mixture, the final water content of the reaction mixture is usually different from the moisture content of the silica raw material used. The amount of water added to the reaction mixture can be adjusted based on the moisture content of the silica raw material used.

[0015] In the context of this invention, the dried granular alkali metal hydroxide is sodium hydroxide (caustic soda, NaOH) and potassium hydroxide (caustic potassium, KOH) or a combination thereof, which are commercially available and typically in granular or flake form. Preferably, the granular alkali metal hydroxide used is air-dried. Therefore, specific storage under a controlled atmosphere or drying or wetting of the alkali metal hydroxide before feeding it to the reaction mixture is not necessary. Although not essential, such preliminary processing or treatment of the alkali metal hydroxide is still possible according to the invention.

[0016] According to the method of the present invention, the weight ratio of dried granular alkaline hydroxide to granular dried silica raw material is 1 part by weight of alkaline hydroxide to 5.25 to 10.5 parts by weight of silica raw material, preferably 1 part by weight of alkaline hydroxide to 5.5 to 10.0 parts by weight of silica raw material, more preferably 1 part by weight of alkaline hydroxide to 5.56 to 10.0 parts by weight of silica raw material.

[0017] According to the method of the present invention, the weight ratio of the dry solids (dry granular alkali metal hydroxide and granular silica raw materials, calculated in a dry state without moisture) to water is 2.55 to 4.3 parts by weight of water per 1 part by weight of solids, preferably 2.59 to 4.0 parts by weight of water per 1 part by weight of solids, and more preferably 2.63 to 3.3 parts by weight of silica raw materials per 1 part by weight of solids.

[0018] Preferably, water is added at a temperature of about 75 °C to about 95 °C, more preferably about 75 °C to about 85 °C.

[0019] Surprisingly, it has been found that, contrary to standard low-speed mixing methods typically used in this field (rotation speeds of about 100-150 rpm and relatively low specific energy inputs within the range of about 10-20 kJ / kg), the mixing method according to the invention is advantageous, wherein the energy input is at least about 1-1.5 orders of magnitude higher compared to ordinary low-speed mixing methods. Mechanical activation is believed to occur in the reaction mixture due to this mixing method. Therefore, according to the invention, the mixing is carried out with a specific energy input of about 200 kJ / kg to 750 kJ / kg, preferably in a stirrer or mixer, correspondingly at rotation speeds of 1000 to 4000 rpm, preferably 2000 rpm. Preferably, the mixing in steps b) and c) is carried out under the same conditions. The mixing is typically carried out in step b) for 25 to 45 minutes, preferably 30 to 40 minutes, and in step c) for 35 to 75 minutes, preferably 40 to 60 minutes. The specific energy input during the mixing process is calculated based on the known amount of raw materials used to produce the alkali metal hydrosilicate (silicate precursor) sample according to the invention and the correlation between the power applied to the mixing element of the mixer and the rotational speed of the mentioned element, these dependencies being specified in the technical guidelines for the mixer used to produce the sample according to the invention.

[0020] The alkalization of the silica raw material by alkalization with alkali metal hydroxide is accompanied by self-heating, resulting in an exothermic dilution / reaction at a temperature of approximately 85-95 °C. Preferably, the temperature of the reaction mixture is maintained between approximately 75 °C and approximately 95 °C by heating or cooling.

[0021] According to a preferred embodiment of the method according to the invention, the viscosity of the product obtained in step c) is determined, for example, by sampling and measuring it with a Brinell viscometer.

[0022] The resulting product can be removed from the process into a suitable container for storage and further use. Preferably, the product is removed after a cooling step, which is preferably carried out by maintaining the product without external heating.

[0023] The method of the present invention can be carried out in an insulated process vessel equipped with a mixer, a feeder for granular silica raw materials, granular alkali metal hydroxides, and heated water, as well as a product outlet.

[0024] The alkali metal hydrosilicates of the present invention do not harden (remain non-solid-state) after storage at standard ambient temperature and pressure (SATP, 25 °C, 100,000 kPa / 1 bar) for at least 28 days. This is determined by loading a material sample into a mold (150 mm cube, prepared according to EN 12390-1:2000) and storing it under SATP for 28 days. After unloading from the mold, the sample is placed on a flat surface (table). The non-hardening of the alkali metal hydrosilicates is demonstrated by the fact that samples of the material according to the present invention lose their cubic shape after the mold stored under SATP is opened, as described above. After opening the mold, the sample generally has a cubic shape; however, the sample should lose its cubic shape within a certain period of time, typically after storage under SATP on a flat surface for about 12 to about 24 hours. Samples that retain a cubic shape under SATP for more than 24 hours are defined as hardened.

[0025] After heat treatment (dehydration) at 250 °C ± 5 °C for 30 min ± 1 min, the alkali metal hydrosilicates according to the invention exhibit the following chemical elemental composition in wt%: silicon: 27-40; aluminum: 0.9-3.5; iron: 2.0-3.5; calcium: 0.2-2.0; magnesium: 0.05-0.5; alkali metals (sodium, potassium, or combinations thereof): 8.0-19.0; oxygen: 43-54; other elements: not exceeding 3.0%, based on XRF data. The heat treatment can be carried out in a laboratory oven such as Binder GmbH (Germany), and the elemental composition can be determined by an XRF spectrometer such as a Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany).

[0026] It has been found that the properties of the materials of this invention are sensitive to the contents of Al, Ca, Mg, and Fe. Compared with the above-mentioned chemical elemental compositions, higher contents of Al, Ca, Mg, and Fe particularly lead to a significant reduction in adhesive properties.

[0027] The alkali metal hydrosilicate of the present invention, after heat treatment (dehydration) at 250 °C ± 5 °C for 30 minutes ± 1 minute (the heat treatment can be carried out in a laboratory oven, such as Binder GmbH (Germany), and the determination can be performed by a moisture analyzer, such as the Sartorius MA 36, modified to use a higher operating temperature during the measurement), has a weight loss of about 45 wt% to about 65 wt%. This weight loss substantially corresponds to the water content in the material.

[0028] The alkali metal hydrosilicate according to the present invention has a Pa of about 100 at a temperature of 25 °C ± 0.5 °C. sec - approximately 70,000 Pa sec, preferably about 150 Pa s - approximately 1600 Pa s, more preferably about 200 Pa s - approximately 1500 Pa The viscosity of s (measured by a Brinell viscometer, such as IKA ROTAVISC hi-vi II).

[0029] The alkali metal hydrosilicate of the present invention has a pH value of about 10.2 to about 13, preferably about 10.6 to about 12. The pH value can be measured using a pH meter, such as model testo 206-ph3.

[0030] It has been unexpectedly discovered that the alkali metal hydrosilicate according to the invention includes a so-called "acidic component" which can be extracted from the precursor material of the invention specifically at elevated temperatures (preferably below 90 °C, more preferably around 70 °C) and reduced pressures (preferably below 0.5 bar, more preferably around 0.1 bar).

[0031] Unbound by theory, it is believed that the relatively low concentration of alkali metals (particularly sodium) in the alkali metal hydrosilicates of this invention, the combination of a large amount of water, and the use of high-energy mixing (compared to conventional low-speed mixing methods) promote the hydrolysis process. Therefore, in the first stage, hydrolysis is achieved, for example, through the following reaction: Na2SiO3+HOH NaHSiO3+Na + +OH -

[0032] In the second stage of hydrolysis, it may be: NaHSiO3+HOH H2SiO3+Na + +OH -

[0033] The general properties of the "acidic component" are very similar to those of a mixture of silicic acids. Considering its hydrophobic properties, the "acidic component" will affect the process of hardening the material.

[0034] The presence of a large amount of hydrophobic acidic components in the material may affect its bonding ability. Therefore, it is desirable that the amount of "acidic components" in the alkali metal hydrosilicate of the present invention does not exceed 10 wt%.

[0035] The present invention also relates to alkali metal hydrosilicates that are obtainable or acquired by the method according to the present invention.

[0036] The alkali metal hydrosilicates of the present invention can be converted into hydrosilicate gels or solid silicates via a sol-gel process, depending on the composition of the alkali metal hydrosilicate and the conditions of the sol-gel process. They possess valuable properties such as adhesiveness, endothermic phase transition capacity, water deposition capacity, and cellulose silicification capacity, making them suitable as fire-retardant materials, materials for preventing thermal runaway, and raw materials for the production of cellulose-based composite materials. The hydrosilicate gels are obtained by heat-treating the alkali metal hydrosilicate, preferably at a temperature of about 60 to about 80 °C for a period of not less than 6 hours. After such treatment, these hydrosilicate gels typically contain about 50% water (moisture), which can be evaporated at a high temperature of about 120 °C to about 250 °C to obtain a so-called "rigid" gel. After the sol-gel process is completed, a solid silicate is obtained, which may be a porous solid silicate or a dense solid silicate. This sol-gel process is typically achieved under more rigid conditions, including elevated temperatures, preferably above about 260 °C, more preferably between about 260 °C and about 350 °C, even more preferably between about 300 °C and about 350 °C, and optionally increased pressure, preferably above about 1.2 bar, more preferably between about 1.2 bar and about 12 bar, even more preferably between about 1.5 bar and about 12 bar. Other methods exist for converting the precursor of the present invention into a solid silicate, such as low pressure, radiation, etc.

[0037] Therefore, another object of the present invention is the use of the alkali metal hydrosilicate according to the invention in the manufacture of fire-retardant materials, in the prevention of thermal runaway, and in the production of cellulose-based composite materials. Detailed Implementation

[0038] The invention will be further illustrated with reference to the following embodiments, but the scope is not limited to the specific embodiments described. The invention includes all combinations of the described and, in particular, does not exclude, preferred features.

[0039] Example 1

[0040] The alkali metal hydrosilicate of the present invention is prepared by using sodium hydroxide as the alkali metal hydroxide. Diatomaceous earth (Type 1) with the composition shown in Table 1 is used as the silica raw material containing not less than 70 wt% amorphous SiO2. The raw material is initially crushed using a jaw crusher and then ground into "siliceous sand". The average particle size of the "sand" is not greater than 0.5 mm, as measured by a vibrating screen AS 300 (Retsch, Germany).

[0041] Table 1. Chemical composition of diatomaceous earth type 1 (determined by Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany))

[0042] The method is carried out in a thermally insulated process vessel equipped with a mixer, a feeder for silica raw materials, air-dried granular sodium hydroxide and heated water, and a metering device for the component - TRIMIX TXR 250 (RAYNERI, France), which has a maximum volume of 250 liters, is equipped with a blade homogenizer and has a total power of 34.2 kW by an electric motor.

[0043] The moisture content of the silica raw material measured before feeding was 76 ± 0.5 wt%.

[0044] Silica raw material is supplied in an amount of 50±1 kg.

[0045] Air-dried granular caustic soda (sodium hydroxide) was added to the process vessel at a rate of 9 ± 0.1 kg and mixed at a speed of 2000 ± 50 rpm (TRIMIX TXR 250 mixing system) for at least 35 minutes with a specific energy input of 500 ± 50 kJ / kg during mixing. After the addition of the granular caustic soda, 10 ± 0.5 kg of hot water at a temperature of 80 ± 5 °C was added while the reaction mixture was being mixed, and the mixing process was carried out for at least 45 minutes.

[0046] The silica raw material is pulverized to particle size. The mixing of the reaction mixture is accompanied by self-heating, which is due to the exothermic effect of the dry alkali hydration of the granulation and the alkalization reaction of the amorphous SiO2. The temperature of the reaction mixture is maintained in the range of 75-95 °C.

[0047] This process continues until a homogeneous viscous material is obtained. Depending on the material's temperature, the viscosity, measured using a Brookfield viscometer IKAROTAVISC hi-vi II, ranges from 100 to 1700 Pa. Within the range of s, the temperature of the material ranges from approximately 90 °C (i.e., the average temperature of the reaction mixture) to 25 °C (i.e., SATP conditions). The material is held for at least 5 minutes without external heating to lower its temperature before the process ends.

[0048] Finally, the obtained materials are discharged into suitable containers for storage and further use.

[0049] The sample of the produced material was dehydrated by drying it in a laboratory oven at 250±5 °C for 30±1 minutes in Binder GmbH (Germany). It had the following elemental composition in wt% as determined by a Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany): silicon - 35.69; aluminum - 2.88; iron - 1.97; calcium - 1.34; magnesium - 0.34; sodium - 9.5; other - 0.03; oxygen - 48.25.

[0050] During the evaporation of moisture from the sample of the generated material at a temperature of 250±1 °C, the amount of evaporated moisture was measured by a Sartorius MA 36 moisture analyzer (modified to use a higher operating temperature during the measurement process) and the measured amount was 45.92 wt%.

[0051] The pH value of the generated material sample, measured using a pH meter model testo 206-pH3, was 11.2.

[0052] To determine the bonding ability of the material obtained by subjecting the resulting precursor material to a sol-gel process, the precursor was used to bond the measuring element of the PROCEQ DYNA Z16 device to a clean surface of a cathode dip-coated (CDC). The CDC was an electrophoretically deposited epoxy film layer with a thickness of 38 ± 3 µm (measured using a QNIX 1500 instrument (AutomationDr. Nix, Germany)) set on a 7075 aluminum alloy sheet with a thickness of 1.3 ± 0.01 mm. The specific volume resistivity of the epoxy resin layer was 15 ± 0.5 MΩ·m (measured using an ohmmeter and a Mili-TO3(H) ammeter (P. FischerElektronik GmbH & Co., Germany). Subsequently, the sample was placed in a laboratory oven at Binder GmbH (Germany) at a temperature of 70 ± 5 °C for at least 6 hours to allow the precursor material to transform into a rigid morphology based on the sol-gel process, thereby obtaining a rigid hydrosilicate gel. The surface tension (adhesion) strength measured by a PROCEQ DYNA Z16 was 4.63 MPa.

[0053] To verify that the generated material maintained a non-solid state under SATP, a sample of the material was loaded into a mold (150 mm cube, prepared according to EN 12390-1:2000) and stored for 28 days under standard ambient temperature and pressure (SATP, 25°C, 100,000 kPa / 1 bar). After being unloaded from the mold, the sample was placed on a flat surface of the stage. During the next 12 hours, the sample lost its cubic form.

[0054] Example 2

[0055] In order to produce another sample of alkali metal hydrosilicate as a precursor for the sodium hydroxide-based sol-gel method according to the present invention, in the first step, the selected porous silica raw material containing not less than 70 wt% amorphous SiO2 (diatomaceous earth type 2) should be crushed using, for example, a jaw crusher and then ground into silica “sand”, the porous silica raw material having the composition presented in Table 2 and the raw material mentioned.

[0056] Table 2. Chemical composition of diatomite type 2 as a raw material for production (alkali metal hydrosilicate as silicate precursor) (determined by benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO GmbH, Germany))

[0057] The average size of the "sand particles" is expected to be no greater than 0.5 mm, as measured by the AS 300 vibrating screen (Retsch, Germany).

[0058] To produce the silicate precursor according to the invention, silica sand is loaded into a thermally insulated process vessel equipped with a mixer, a feeder containing silica "sand" and heated water, and a feed port (hatchway) for filling with air-dried granular caustic alkali—sodium hydroxide. Furthermore, the process vessel may be equipped with a controllable heater (e.g., with a water jacket) because it is in the reactor of the mixing system, a TRIMIX TXR 250 (RAYNERI, France) with a maximum volume of 250 liters, equipped with a blade homogenizer and an electric motor with a total power of 34.2 kW.

[0059] The moisture content of the silica raw material measured before feeding was 74 ± 0.5 wt%.

[0060] Silica raw material is supplied in an amount of 100±1 kg.

[0061] In the second step, air-dried granular caustic soda (sodium hydroxide) is added to the process vessel at a rate of 10 ± 0.1 kg, while the material is mixed in a TRIMIX TXR 250 reactor at a speed of 2000 ± 20 rpm for at least 35 minutes with a specific energy input of 300 ± 30 kJ / kg. After the addition of the granular caustic soda, 25 ± 0.5 kg of hot water at a temperature of 80 ± 5 °C is added while the reaction mixture is being mixed, and the mixing process is carried out for at least 45 minutes.

[0062] The mixing of the reaction mixture is accompanied by self-heating, which is due to the exothermic effect of the hydration of the particulate dry alkali and the alkalization reaction of amorphous SiO2. The temperature of the reaction mixture is maintained in the range of 75-95 °C.

[0063] This process continues until a homogeneous viscous material is obtained. Depending on the material's temperature, the viscosity, measured using a Brookfield viscometer IKAROTAVISC hi-vi II, ranges from 500 to 5800 Pa. Within the range of s, the temperature of the material ranges from approximately 90 °C (i.e., the average temperature of the reaction mixture) to 25 °C (i.e., SATP conditions). The material is held for at least 5 minutes without external heating to lower its temperature before the process ends.

[0064] Finally, the obtained materials are discharged into suitable containers for storage and further use.

[0065] The sample of the produced material was dehydrated by drying it in a laboratory oven at 250±5 °C for 30±1 minutes in Binder GmbH (Germany). It had the following elemental composition in wt% as determined by a Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany): silicon - 35.39; aluminum - 3.14; iron - 2.14; calcium - 1.98; magnesium - 0.48; sodium - 8.65; other - 0.03; oxygen - 46.62.

[0066] During the evaporation of moisture from the sample of the generated material at a temperature of 250±1 °C, the amount of evaporated moisture was measured by a Sartorius MA 36 moisture analyzer (modified to use a higher operating temperature during the measurement process) and the measured amount was 46.28 wt%.

[0067] The pH value of the generated material sample, measured using a pH meter model testo 206-pH3, was 11.

[0068] To determine the adhesive properties of the material obtained from the sol-gel process, a precursor material was used to bond the measuring element of a PROCEQ DYNA Z16 apparatus to a clean surface of a cathodic electrophoretic coating (CDC). This coating was a 38±3 µm thick electrophoretic epoxy film (measured using a QNIX 1500 instrument from Automation Dr. NIX, Germany), coated on a 1.3±0.01 mm thick 7075 aluminum alloy plate. The specific volume resistivity of the epoxy layer was 15±0.5 MΩ·m (measured using a Mili-TO3 ohmmeter and ammeter from H.-P. FISCHER ELEKTRONIK GmbH & Co., Germany). The bonded sample was then placed in a laboratory oven at Binder GmbH, Germany, and kept at 70±5 °C for at least 6 hours to allow the precursor material to transform into a rigid structure through the sol-gel process, thus obtaining a rigid hydrated silicate gel. The surface tension (adhesive strength) measured by the PROCEQ DYNA Z16 was 4.61 MPa.

[0069] To verify that the generated material maintained a non-solid state under SATP, a sample of the material was loaded into a mold (150 mm cube, prepared according to EN 12390-1:2000) and stored for 28 days under standard ambient temperature and pressure (SATP, 25°C, 100,000 kPa / 1 bar). After being unloaded from the mold, the sample was placed on a flat surface of the stage. During the next 18 hours, the sample lost its cubic shape.

[0070] Example 3 (Comparative)

[0071] In order to produce a silicate material sample with a higher aluminum (Al) content than the silicate precursor according to the invention in the first step, the selected porous silicate raw material containing not less than 70 wt% amorphous SiO2 (metallurgical slag type 1) should be crushed using, for example, a jaw crusher and the raw material mentioned therein, and then ground into silicate “sand”.

[0072] Table 3. Chemical composition of metallurgical slag used as raw material in the production of silicate materials (determined by Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany)).

[0073] The average size of the "sand particles" is expected to be no greater than 0.5 mm, as measured by the AS 300 vibrating screen (Retsch, Germany).

[0074] To produce the silicate precursor according to the invention, silica sand is loaded into a thermally insulated process vessel equipped with a mixer, a feeder containing silica "sand" and heated water, and a feed orifice for filling with air-dried granular caustic alkali—sodium hydroxide. Furthermore, the process vessel may be equipped with a controllable heater (e.g., with a water jacket) because it is located within the reactor of the mixing system. The TRIMIX TXR 250 (RAYNERI, France) has a maximum volume of 250 liters, is equipped with a bladed homogenizer, and has an electric motor with a total power of 34.2 kW.

[0075] The moisture content of the silica raw material measured before feeding was 75 ± 0.5 wt%.

[0076] Silica raw material is supplied in an amount of 100±1 kg.

[0077] In the second step, air-dried granular caustic soda (sodium hydroxide) is added to the process vessel at a rate of 10 ± 0.1 kg, while the material is mixed in a TRIMIX TXR 250 reactor at a speed of 2000 ± 20 rpm, with a specific energy input of 300 ± 30 kJ / kg for at least 35 minutes during mixing. After the addition of the granular caustic soda, 25 ± 0.5 kg of hot water at a temperature of 80 ± 5 °C is added while the reaction mixture is being mixed, and the mixing process is carried out for at least 45 minutes.

[0078] The mixing of the reaction mixture is accompanied by self-heating, which is due to the exothermic effect of the hydration of the particulate dry alkali and the alkalization reaction of amorphous SiO2. The temperature of the reaction mixture is maintained in the range of 75-95 °C.

[0079] This process continues until a homogeneous viscous material is obtained. The viscosity of the material, measured using a Brookfield viscometer IKA ROTAVISC hi-vi II, ranges from 1000 to 80000 Pa. The temperature range is within the range of s, depending on the temperature of the material, which ranges from approximately 90°C (i.e., the average temperature of the reaction mixture) to 25°C (i.e., SATP conditions). The material is held for at least 5 minutes without external heating to lower its temperature before the process ends.

[0080] Finally, the obtained materials are discharged into suitable containers for storage and further use.

[0081] The sample of the produced material was dehydrated by drying it in a laboratory oven at 250±5 °C for 30±1 minutes in Binder GmbH (Germany). It had the following elemental composition in wt% as determined by a Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany): silicon - 30.52; aluminum - 9.98; iron - 1.77; calcium - 1.88; magnesium - 0.79; sodium - 6.02; potassium - 0.62; oxygen - 48.42.

[0082] To test the adhesive properties of the material prepared via the sol-gel process, the measuring element of a PROCEQ DYNA Z16 instrument was bonded to a clean surface treated with cathodic electrophoresis (CDC) using the precursor material. The electrophoretic epoxy film, with a thickness of 38 ± 3 µm (measured using a QNIX 1500 instrument from Automation Dr. NIX, Germany), was coated on a 1.3 ± 0.01 mm thick 7075 aluminum alloy plate. The volume resistivity of the epoxy coating was 15 ± 0.5 MΩ·m (measured using a Mili-TO3 ohmmeter and ammeter from H.-P. FISCHER ELEKTRONIK GmbH & Co., Germany). The bonded sample was then placed in a laboratory oven at Binder GmbH, Germany, and kept at 70 ± 5 °C for at least 6 hours to allow the precursor material to transform into a rigid structure via the sol-gel process, resulting in a rigid hydrated silicate gel. The surface tension (adhesion) strength measured by the PROCEQ DYNA Z16 was 0.24 MPa.

[0083] Therefore, the aluminum concentration value according to the present invention appears to be optimal.

[0084] Example 4 (Comparative)

[0085] In order to produce a silicate material sample with a higher calcium (Ca) content than the silicate precursor according to the invention in the first step, a porous silicate raw material containing about 70 wt% amorphous SiO2 (metallurgical slag type 2) (with the composition shown in Table 4) should be crushed using, for example, a jaw crusher, and then ground into silicate “sand”.

[0086] Table 4. Chemical composition of metallurgical slag used as raw material for the production of silicate materials (determined by Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany)).

[0087] The average size of the "sand particles" is expected to be no greater than 0.5 mm, as measured by the AS 300 vibrating screen (Retsch, Germany).

[0088] To produce the silicate precursor according to the invention, silica sand is loaded into a thermally insulated process vessel equipped with a mixer, a feeder containing silica "sand" and heated water, and a feed orifice for filling with air-dried granular caustic alkali—sodium hydroxide. Furthermore, the process vessel may be equipped with a controllable heater (e.g., with a water jacket) because it is located within the reactor of the mixing system. The TRIMIX TXR 250 (RAYNERI, France) has a maximum volume of 250 liters, is equipped with a bladed homogenizer, and has an electric motor with a total power of 34.2 kW.

[0089] The moisture content of the silica raw material measured before feeding was 75 ± 0.5 wt%.

[0090] Silica raw material is supplied in an amount of 100±1 kg.

[0091] In the second step, air-dried granular caustic soda (sodium hydroxide) is added to the process vessel at a rate of 10 ± 0.1 kg, while the material is mixed in a TRIMIX TXR 250 reactor at a speed of 2000 ± 20 rpm for at least 35 minutes with a specific energy input of 300 ± 30 kJ / kg. After the addition of the granular caustic soda, 25 ± 0.5 kg of hot water at a temperature of 80 ± 5 °C is added while the reaction mixture is being mixed, and the mixing process is carried out for at least 45 minutes.

[0092] The mixing of the reaction mixture is accompanied by self-heating, which is due to the exothermic effect of the hydration of the particulate dry alkali and the alkalization reaction of amorphous SiO2. The temperature of the reaction mixture is maintained in the range of 75-95 °C.

[0093] This process continues until a homogeneous viscous material is obtained. Depending on the material's temperature, the viscosity, measured using a Brookfield viscometer IKAROTAVISC hi-vi II, ranges from 700 to 40000 Pa. Within the range of s, the temperature ranges from approximately 90 °C (i.e., the average temperature of the reaction mixture) to 25 °C (i.e., SATP conditions). The material is held for at least 5 minutes without external heating to lower its temperature before the process ends.

[0094] Finally, the obtained materials are discharged into suitable containers for storage and further use.

[0095] The sample of the produced material was dehydrated by drying it in a laboratory oven at 250±5 °C for 30±1 minutes in Binder GmbH (Germany). It had the following elemental composition in wt% as determined by a Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany): silicon - 32.15; aluminum - 0.43; iron - 2.19; calcium - 10.23; magnesium - 0.91; sodium - 6.7; potassium - 1.51; other - 0.27; oxygen - 45.61.

[0096] To evaluate the adhesive properties of the material obtained through the sol-gel process, a measuring element of a PROCEQDYNA Z16 instrument was bonded to a clean surface of a cathodic electrophoretic coating (CDC) using a precursor material. The electrophoretic epoxy film, with a thickness of 38 ± 3 µm (measured using a QNIX 1500 instrument from Automation Dr. NIX, Germany), was coated on a 1.3 ± 0.01 mm thick 7075 aluminum alloy plate. The volume resistivity of the epoxy coating was 15 ± 0.5 MΩ·m (measured using a Mili-TO3 ohmmeter and ammeter from H.-P. FISCHER ELEKTRONIK GmbH & Co., Germany). The sample was then placed in a laboratory oven at 70 ± 5 °C for at least 6 hours to allow the precursor material to transform into a rigid form via the sol-gel process, thus obtaining a rigid hydrated silicate gel. The surface tension (adhesive strength) measured by the PROCEQDYNA Z16 was 0.12 MPa.

[0097] Therefore, the calcium concentration value according to the present invention appears to be optimal.

[0098] Example 5 (Comparative)

[0099] In order to produce silicate material samples with a higher iron (Fe) content compared to the silicate precursors according to the invention, in the first step, a selected porous silica raw material containing not less than 70 wt% amorphous SiO2 (diatomite type 1) (with the composition given in Table 1) should be crushed in a quantity of 90 kg using, for example, a jaw crusher and mixed with 10 kg of crushed and ground copper metallurgical slag (with the composition given in Table 5), and then the mixture should be ground into silica "sand".

[0100] Table 5. Chemical composition of metallurgical copper slag as a raw material for silicate production (determined by Benchtop XRF Spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany)).

[0101] The average size of the "sand particles" is expected to be no greater than 0.5 mm, as measured by the AS 300 vibrating screen (Retsch, Germany).

[0102] To produce the silicate precursor according to the invention, silica sand is loaded into a thermally insulated process vessel equipped with a mixer, a feeder containing silica "sand" and heated water, and a feed orifice for filling with air-dried granular caustic alkali—sodium hydroxide. Furthermore, the process vessel may be equipped with a controllable heater (e.g., with a water jacket) because it is located within the reactor of the mixing system. The TRIMIX TXR 250 (RAYNERI, France) has a maximum volume of 250 liters, is equipped with a bladed homogenizer, and has an electric motor with a total power of 34.2 kW.

[0103] The moisture content of the silica raw material measured before feeding was 75 ± 0.5 wt%.

[0104] Silica raw material is supplied in an amount of 100±1 kg.

[0105] In the second step, air-dried granular caustic soda (sodium hydroxide) is added to the process vessel at a rate of 10 ± 0.1 kg, while the material is mixed in a TRIMIX TXR 250 reactor at a speed of 2000 ± 20 rpm for at least 35 minutes with a specific energy input of 300 ± 30 kJ / kg. After the addition of the granular caustic soda, 25 ± 0.5 kg of hot water at a temperature of 80 ± 5 °C is added while the reaction mixture is being mixed, and the mixing process is carried out for at least 45 minutes.

[0106] The mixing of the reaction mixture is accompanied by self-heating, which is due to the exothermic effect of the hydration of the particulate dry alkali and the alkalization reaction of amorphous SiO2. The temperature of the reaction mixture is maintained in the range of 75-95 °C.

[0107] This process continues until a homogeneous viscous material is obtained. Depending on the material's temperature, the viscosity, measured using a Brookfield viscometer IKAROTAVISC hi-vi II, ranges from 800 to 52000 Pa. Within the range of s, the temperature ranges from approximately 90 °C (i.e., the average temperature of the reaction mixture) to 25 °C (i.e., SATP conditions). The material is held for at least 5 minutes without external heating to lower its temperature before the process ends.

[0108] Finally, the obtained materials are discharged into suitable containers for storage and further use.

[0109] The sample of the produced material was dehydrated by drying it in a laboratory oven at 250±5 °C for 30±1 minutes in Binder GmbH (Germany). It had the following elemental composition in wt% as determined by a Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany): silicon - 35.23; aluminum - 2.94; iron - 5.9; calcium - 1.54; magnesium - 0.37; sodium - 5.63; other - 0.08; oxygen - 48.31.

[0110] To evaluate the adhesive properties of materials obtained through the sol-gel process, a precursor material was bonded to a clean surface of a cathodic electrophoretic coating (CDC) using a PROCEQDYNA Z16 instrument. The electrophoretic epoxy film, with a thickness of 38 ± 3 µm (measured using a QNIX 1500 instrument from Automation Dr. NIX, Germany), was coated on a 1.3 ± 0.01 mm thick 7075 aluminum alloy plate. The volume resistivity of the epoxy layer was 15 ± 0.5 MΩ·m (measured using a Mili-TO3 ohmmeter and ammeter from H.-P. FISCHER ELEKTRONIK GmbH & Co., Germany). The bonded component was then placed in a laboratory oven at 70 ± 5 °C for at least 6 hours to allow the precursor material to transform into a rigid structure via the sol-gel process, thus obtaining a rigid hydrated silicate gel. The surface tension (adhesion) strength measured by the PROCEQDYNA Z16 was 0.1 MPa.

[0111] Example 6

[0112] The alkali metal hydrosilicate of the present invention is prepared by using potassium hydroxide as the alkali metal hydroxide. As a silica raw material containing not less than 70 wt% amorphous SiO2, diatomaceous earth (Type 1) having the composition shown in Table 1 is used. The raw material is initially crushed using a jaw crusher and then ground into "siliceous sand".

[0113] The average particle size of the "sand" is no greater than 0.5 mm, as measured by a vibrating sieve AS 300 (Retsch, Germany).

[0114] To produce the silicate precursor according to the invention, silica sand is loaded into a thermally insulated process vessel equipped with a mixer, a feeder containing silica "sand" and heated water, and a feed orifice for filling with air-dried granular caustic alkali—potassium hydroxide. Furthermore, the process vessel may be equipped with a controllable heater (e.g., with a water jacket) because it is located within the reactor of the mixing system. The TRIMIX TXR 250 (RAYNERI, France) has a maximum volume of 250 liters, is equipped with a bladed homogenizer, and has an electric motor with a total power of 34.2 kW.

[0115] The moisture content of the silica raw material measured before feeding was 76 ± 0.5 wt%.

[0116] Silica raw material is supplied in an amount of 50±1 kg.

[0117] In the second step, air-dried granular caustic soda (potassium hydroxide) is added to the process vessel at a rate of 9.4 ± 0.1 kg, while the material is mixed in the reactor of the mixing system at a rate of 2000 ± 20 rpm using TRIMIX TXR 250, with a specific energy input of 500 ± 50 kJ / kg for at least 35 minutes during mixing. After the addition of the granular caustic soda, 14 ± 0.5 kg of hot water at a temperature of 80 ± 5 °C is added while the reaction mixture is being mixed, and the mixing process is carried out for at least 45 minutes.

[0118] The mixing of the reaction mixture is accompanied by self-heating, which is due to the exothermic effect of the hydration of the particulate dry alkali and the alkalization reaction of amorphous SiO2. The temperature of the reaction mixture is maintained in the range of 75-95 °C.

[0119] This process continues until a homogeneous viscous material is obtained. Depending on the material's temperature, the viscosity, measured using a Brookfield viscometer IKAROTAVISC hi-vi II, ranges from 800 to 52000 Pa. Within the range of s, the temperature ranges from approximately 90 °C (i.e., the average temperature of the reaction mixture) to 25 °C (i.e., SATP conditions). The material is held for at least 5 minutes without external heating to lower its temperature before the process ends.

[0120] Finally, the obtained materials are discharged into suitable containers for storage and further use.

[0121] The material samples produced were dehydrated by drying in a laboratory oven at 250±5 °C for 30±1 minutes in Binder GmbH (Germany). The samples had the following elemental composition in wt% as determined by a Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany): silicon - 34.93; aluminum - 2.83; iron - 1.92; calcium - 1.31; magnesium - 0.36; potassium - 12.22; other - 0.02; oxygen - 46.41.

[0122] During the evaporation of moisture from the sample of the generated material at a temperature of 250±1 °C, the amount of evaporated moisture was measured by a Sartorius MA 36 moisture analyzer (modified to use a higher operating temperature during the measurement process) and the measured amount was 45.82 wt%.

[0123] The pH value of the generated material sample, measured using a pH meter model testo 206-pH3, was 11.

[0124] To determine the adhesive properties of the material obtained from the precursor material via a sol-gel process, the measuring element of a PROCEQDYNA Z16 instrument was bonded to a clean surface of a cathodic electrophoretic coating (CDC) using the precursor. The CDC coating had a thickness of 38±3µm (measured using a QNIX 1500 instrument from Automation Dr. NIX, Germany), and was applied to a 1.3±0.01 mm thick 7075 aluminum alloy plate. The volume resistivity of the epoxy layer was 15±0.5 MΩ·m (measured using a Mili-TO3 ohmmeter and ammeter from H.-P. FISCHER ELEKTRONIK GmbH & Co., Germany). The material was then placed in a laboratory oven at 70±5 °C for at least 6 hours, allowing the precursor material to transform into a rigid structure via the sol-gel process, resulting in a rigid hydrated silicate gel. The surface tension (adhesive strength) measured by the PROCEQDYNA Z16 was 4.58 MPa.

[0125] To verify that the generated material remained in a non-solid state under SATP (NTP), a sample of the material was loaded into a mold (150 mm cube, prepared according to EN 12390-1:2000) and stored for 28 days under standard ambient temperature and pressure (SATP, 25°C, 100,000 kPa / 1 bar). After being unloaded from the mold, the sample was placed on a flat surface of the stage. During the next 15 hours, the sample lost its cubic shape.

[0126] Example 7

[0127] The alkali metal hydrosilicate of the present invention is prepared by using potassium hydroxide as the alkali metal hydroxide. As a silica raw material containing not less than 70 wt% amorphous SiO2, diatomaceous earth (Type 1) having the composition shown in Table 1 is used. The raw material is initially crushed using a jaw crusher and then ground into "siliceous sand".

[0128] The average particle size of the "sand" is no greater than 0.5 mm, as measured by a vibrating sieve AS 300 (Retsch, Germany).

[0129] To produce the silicate precursor according to the invention, silica sand is loaded into a thermally insulated process vessel equipped with a mixer, a feeder containing silica "sand" and heated water, and a feed orifice for filling with air-dried granular caustic alkali—potassium hydroxide. Furthermore, the process vessel may be equipped with a controllable heater (e.g., with a water jacket) because it is located within the reactor of the mixing system. The TRIMIX TXR 250 (RAYNERI, France) has a maximum volume of 250 liters, is equipped with a bladed homogenizer, and has an electric motor with a total power of 34.2 kW.

[0130] The moisture content of the silica raw material measured before feeding was 75 ± 0.5 wt%.

[0131] Silica raw material is supplied in an amount of 100±1 kg.

[0132] In the second step, air-dried granular caustic soda (potassium hydroxide) is added to the process vessel at a rate of 19 ± 0.1 kg, while the material is mixed in the reactor of the mixing system at a rate of 2000 ± 20 rpm using TRIMIX TXR 250, with a specific energy input of 300 ± 30 kJ / kg for at least 35 minutes during mixing. After the addition of the granular caustic soda, 25 ± 0.5 kg of hot water at a temperature of 80 ± 5 °C is added while the reaction mixture is being mixed, and the mixing process is carried out for at least 45 minutes.

[0133] The mixing of the reaction mixture is accompanied by self-heating, which is due to the exothermic effect of the hydration of the particulate dry alkali and the alkalization reaction of amorphous SiO2. The temperature of the reaction mixture is maintained in the range of 75-95 °C.

[0134] This process continues until a homogeneous viscous material is obtained. Depending on the material's temperature, the viscosity, measured using a Brookfield viscometer IKAROTAVISC hi-vi II, ranges from 800 to 52000 Pa. Within the range of s, the temperature ranges from approximately 90 °C (i.e., the average temperature of the reaction mixture) to 25 °C (i.e., SATP conditions). The material is held for at least 5 minutes without external heating to lower its temperature before the process ends.

[0135] Finally, the obtained materials are discharged into suitable containers for storage and further use.

[0136] The sample of the produced material was dehydrated by drying it in a laboratory oven at 250±5 °C for 30±1 minutes in Binder GmbH (Germany). It had the following elemental composition in wt% as determined by a Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany): silicon - 32.78; aluminum - 2.92; iron - 1.08; calcium - 1.89; magnesium - 0.44; sodium - 2.91; potassium - 11.76; other - 0.03; oxygen - 46.19.

[0137] During the evaporation of moisture from the sample of the generated material at a temperature of 250±1 °C, the amount of evaporated moisture was measured by a Sartorius MA 36 moisture analyzer (modified to use a higher operating temperature during the measurement process) and the measured amount was 43.41 wt%.

[0138] The pH value of the generated material sample, measured using the pH meter model testo 206-pH3, was 10.9.

[0139] To determine the adhesive properties of the material obtained through the sol-gel process, the measuring element of the PROCEQ DYNA Z16 instrument was adhered to a clean surface of a cathodic electrophoretic coating (CDC) using the precursor material. This coating was a 38±3µm thick electrophoretic epoxy film (measured using a QNIX 1500 instrument from Automation Dr. NIX, Germany), located on a 1.3±0.01mm thick 7075 aluminum alloy plate, with a volume resistivity of 15±0.5 MΩ·m (measured using a Mili-TO3 ohmmeter from H.-P. FISCHER ELEKTRONIK GmbH & Co., Germany). The bonded assembly was then placed in a laboratory oven at Binder GmbH, Germany, and cured at 70±5 °C for at least 6 hours, allowing the precursor material to transform into a rigid structure through the sol-gel process, thus obtaining a rigid hydrated silicate gel. The surface tension (adhesive strength) measured by the PROCEQ DYNA Z16 was 4.12 MPa.

[0140] To confirm that the generated material maintained a non-solid state under SATP, a sample of the material was loaded into a mold (150 mm cube, prepared according to EN 12390-1:2000) and stored for 28 days under standard ambient temperature and pressure (SATP, 25°C, 100,000 kPa / 1 bar). After being unloaded from the mold, the sample was placed on a flat surface of the stage. During the next 15 hours, the sample lost its cubic shape.

[0141] Example 8 (Comparative)

[0142] To produce a reference sample of sodium hydroxide-based silicate gel material according to the closest prior art (patent application WO 2021248173), a silica raw material containing not less than 70 wt% amorphous SiO2 (diatomaceous earth) (type 1) was used, the composition of which is shown in Table 1. The raw material was initially crushed using a jaw crusher and then ground into “siliceous sand”.

[0143] The average particle size of the "sand" is no greater than 0.5 mm, as measured by a vibrating sieve AS 300 (Retsch, Germany).

[0144] Siliceous sand should be loaded into an insulated process vessel equipped with a mixer, a feeder for the silica "sand" and heated water, and a feed orifice for filling with air-dried granular caustic alkali—sodium hydroxide—to produce a silicate precursor as described in this invention. Furthermore, the process vessel may be equipped with a controllable heater (e.g., with a water jacket) in the reactor of the mixing system, a TRIMIX TXR 250 (RAYNERI, France)—with a maximum volume of 250 liters—equipped with a turbine-type impeller and a separate electric motor with a power of 2.0 kW.

[0145] The moisture content of the silica raw material measured before feeding was 41 ± 0.5 wt%.

[0146] Silica raw material is supplied in an amount of 50±1 kg.

[0147] In the second step, air-dried granular caustic soda (sodium hydroxide) is added to the process vessel at a rate of 25 ± 0.1 kg, while the material is mixed in the reactor of the mixing system at a rate of 150 ± 5 rpm using TRIMIX TXR 250, with a specific energy input of 20 ± 2 kJ / kg for at least 25 minutes during mixing. After adding the granular caustic soda, 10 ± 0.5 kg of hot water at a temperature of 80 ± 5 °C is added while the reaction mixture is being mixed, and the mixing process is carried out for at least 35 minutes.

[0148] The mixing of the reaction mixture is accompanied by self-heating, which is due to the exothermic effect of the hydration of the particulate dry alkali and the alkalization reaction of amorphous SiO2. The temperature of the reaction mixture is maintained in the range of 75-95 °C.

[0149] Continue this process until a homogeneous viscous material is obtained. The viscosity of the material, measured using a Brookfield viscometer IKA ROTAVISC hi-vi II, should be higher than 1500 Pa. s and can reach over 180,000 Pa The value of s depends on the temperature of the material, which ranges from approximately 90 °C (i.e., the average temperature of the reaction mixture) to 25 °C (i.e., SATP conditions). The material is held for at least 5 minutes without external heating to lower its temperature before the process ends.

[0150] Finally, the obtained materials are discharged into suitable containers for storage and further use.

[0151] The sample of the produced material was dehydrated by drying it in a laboratory oven at 250±5 °C for 30±1 minutes in Binder GmbH (Germany). It had the following elemental composition in wt% as determined by a Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany): silicon - 27.2; aluminum - 3.07; iron - 1.65; calcium - 1.57; magnesium - 0.37; sodium - 23.65; other - 0.02; oxygen - 42.47.

[0152] During the evaporation of moisture from the sample of the generated material at a temperature of 250±1 °C, the amount of evaporated moisture was measured by a Sartorius MA 36 moisture analyzer (modified to use a higher operating temperature during the measurement process) and the measured amount was 30.7 wt%.

[0153] The pH value of the generated material sample, measured using the pH meter model testo 206-pH3, was 9.8.

[0154] To evaluate the adhesive properties of the precursor material prepared by the sol-gel process, the measuring element of a PROCEQ DYNA Z16 instrument was used to bond the precursor to a clean cathodic electrophoretic coating (CDC) surface. This coating was an electrophoretic epoxy film with a thickness of 38±3 µm, measured using a QNIX 1500 instrument from Automation Dr. NIX, Germany, applied to a 1.3±0.01 mm thick 7075 aluminum alloy plate; the volume resistivity of the epoxy coating was 15±0.5 MΩ·m, measured using a Mili-TO3 ohmmeter and ammeter from H.-P. FISCHER ELEKTRONIK GmbH & Co., Germany. Subsequently, it was placed in a laboratory oven at Binder GmbH, Germany, and cured at 70±5 °C for at least 6 hours, allowing the precursor material to transform into a rigid form based on the sol-gel process, thus obtaining a rigid hydrated silicate gel. The surface tension (adhesive) strength measured by PROCEQ DYNA Z16 is 0.01 MPa.

[0155] To investigate whether the generated material retained its non-solid-state properties under SATP conditions, a sample of the material was loaded into a mold (150 mm cube, prepared according to EN 12390-1:2000) and stored for 28 days under standard ambient temperature and pressure (SATP, 25 °C, 100,000 kPa / 1 bar). After being unloaded from the mold, the sample was placed on a flat surface of the stage. During the following 24 hours, the sample did not lose its cubic shape.

[0156] Example 9

[0157] To determine the optimal range of the main parameters of the material according to the invention, further experiments were conducted using diatomaceous earth as a raw material. Alkali metal hydrosilicate samples of the invention were prepared as described in Examples 1 and 2 above. However, as indicated in Tables 9.1 and 9.2 respectively, different ratios of silica raw material (diatomaceous earth) were used in each sample. Furthermore, Tables 9.1 and 9.2 show the results of different tests for performance characteristics, which were conducted as described in Example 1 above.

[0158] Table 9.1. Composition and performance characteristics.

[0159]

[0160] Table 9.2. Composition and performance characteristics.

[0161]

[0162] The data shown in Tables 9.1 and 9.2 confirm that the scope of protection claimed by the parameters of the present invention is optimal.

[0163] Example 10

[0164] To determine the possible dilution range of the precursor material of the present invention, an alkali metal hydrosilicate obtained according to Example 1 was used. This material was mixed with an additional amount of water, as shown in Table 10. The mixing of the precursor material with the additional water was carried out in a HOBART N50 mixer. The pH value of the diluted material was measured as described in Example 1. Furthermore, as described in Example 1, the surface tension strength of each coating on the CDC surface was measured for different samples, wherein the diluted precursor was subjected to a sol-gel process by gluing the measuring element of the PROCEQ DYNA Z16 device onto the CDC surface using the precursor material (alkali metal hydrosilicate) and storing it in a laboratory oven at 70 ± 5 °C for at least 6 hours. The results of the above measurements are presented in Table 10.

[0165] Table 10. Composition and performance characteristics of different samples of diluted precursor materials (alkali metal hydrosilicates)

[0166] The data shown in Table 10 indicate that the appropriate surface tension strength is maintained at approximately 8 pH.

[0167] Example 11

[0168] To determine the optimal mixing rate range during the preparation of the silicate precursor material (alkali metal hydrosilicate), the initial material prepared according to Example 1 was used. Samples of the mentioned material were produced using a high-speed laboratory stirrer (Mixer Direct, USA) with a maximum power of approximately 150 W and a maximum rotation speed of 6000 rpm. The composition of the components is presented in Table 9.2. The viscosity and surface tensile strength of each sample were measured as described in Example 1. The results are presented in Table 11.

[0169] Table 11 Composition and performance characteristics of different samples of the material (alkali metal hydrosilicate)

[0170] The data shown in Table 11 indicate that the rotational speed after mixing affects the surface tension strength of the coating obtained during the sol-gel process of the precursor material.

[0171] Example 12

[0172] To determine the optimal range of the so-called acidic components, 10 kg batches of each sample from the precursor material (alkali metal hydrosilicate) manufactured as described in Example 9 were studied. The initial properties of the samples are presented in Table 9.1.

[0173] Each sample was heated to 70 ± 5 °C in a laboratory oven at Binder GmbH (Germany), followed by evacuation to 0.1 bar in a vacuum chamber over approximately 15 minutes. The samples were then maintained in the chamber under vacuum for 6–8 hours without pumping or additional heating.

[0174] Following this treatment, a relatively transparent liquid layer was observed on the surfaces of samples 12.1, 12.3, 12.4, and 12.5. The liquid could be separated into individual containers for samples 12.1, 12.4, and 12.5. The pH value of the liquid was measured using a pH meter model testo206-pH3. For samples 12.2 and 12.3, the pH value was measured on these surfaces using pH indicator paper.

[0175] The results of the above processing are presented in Table 12.

[0176] Table 12. Composition and performance characteristics of different samples of the material.

[0177]

[0178] The data shown in Table 12 confirm that excessive amounts of “acidic components” affect the surface tension strength of the coating obtained from the sol-gel process of this precursor material.

[0179] Example 13

[0180] To prepare another alkali metal hydrosilicate sample of a sodium hydroxide-based silicate precursor for a sol-gel process according to the present invention, in the first step, a selected porous silica raw material (containing not less than 70 wt% amorphous SiO2, which is an amorphous silicon dioxide) is used, with a byproduct of ferroalloy production (microsilica powder) having the composition as presented in Table 13, and the raw material mentioned should be crushed, for example, using a jaw crusher, and then ground into silica "sand".

[0181] Table 13. Chemical composition of amorphous silica byproduct (microsilica powder) produced from ferroalloys used as raw materials for the preparation of the materials of the present invention (alkali metal hydrosilicate as silicate precursor) (determined by Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany))

[0182] The average size of the "sand particles" is expected to be no greater than 0.5 mm, as measured by the AS 300 vibrating screen (Retsch, Germany).

[0183] The silica sand should be loaded into an insulated process vessel equipped with a mixer, a feeder for the silica "sand" and heated water, and a feed path for filling with air-dried granular caustic alkali—sodium hydroxide—to produce the silicate precursor according to the invention. Furthermore, the process vessel may be equipped with a controllable heater (e.g., with a water jacket) because it is in the reactor of the mixing system, a TRIMIX TXR 250 (RAYNERI, France) with a maximum volume of 250 liters, equipped with a blade homogenizer and an electric motor with a total power of 34.2 kW.

[0184] The moisture content of the silica raw material measured before feeding was 75 ± 0.5 wt%.

[0185] Silica raw material is supplied in an amount of 100±1 kg.

[0186] In the second step, air-dried granular caustic soda (sodium hydroxide) is added to the process vessel at a rate of 19 ± 0.1 kg, while the material is mixed in a TRIMIX TXR 250 reactor at a rate of 2000 ± 20 rpm, with a specific energy input of 300 ± 30 kJ / kg for at least 35 minutes during mixing. After the addition of the granular caustic soda, 25 ± 0.5 kg of hot water at a temperature of 80 ± 5 °C is added while the reaction mixture is being mixed, and the mixing process is carried out for at least 45 minutes.

[0187] The mixing of the reaction mixture is accompanied by self-heating, which is due to the exothermic effect of the hydration of the particulate dry alkali and the alkalization reaction of amorphous SiO2. The temperature of the reaction mixture is maintained in the range of 75-95 °C.

[0188] This process continues until a homogeneous viscous material is obtained. Depending on the material temperature, the viscosity, measured using a Brookfield viscometer IKAROTAVISC hi-vi II, ranges from 450 to 4600 Pa. Within the range of s, the temperature ranges from approximately 90 °C (i.e., the average temperature of the reaction mixture) to 25 °C (i.e., SATP conditions). The material is held for at least 5 minutes before the process ends, without external heating to lower its temperature.

[0189] Finally, the obtained materials are discharged into suitable containers for storage and further use.

[0190] The sample of the produced material was dehydrated by drying it in a laboratory oven at 250±5 °C for 30±1 minutes in Binder GmbH (Germany). It had the following elemental composition in wt% as determined by a Benchtop XRF spectrometer SPECTROCUBE C (Ametek / SPECTRO, Germany): silicon - 37.19; aluminum - 0.54; iron - 1.08; calcium - 0.76; magnesium - 0.47; sodium - 10.71; other - 0.28; oxygen - 48.13.

[0191] During the evaporation of moisture from the sample of the generated material at a temperature of 250±1 °C, the amount of evaporated moisture was measured by a Sartorius MA 36 moisture analyzer (modified to use a higher operating temperature during the measurement process) and the measured amount was 45.74 wt%.

[0192] The pH value of the generated material sample, measured using the pH meter model testo 206-pH3, was 10.9.

[0193] To determine the adhesive properties of materials obtained from precursors treated with a sol-gel process, the precursor was used to bond the measuring element of a PROCEQ DYNA Z16 instrument to a clean surface of a cathodic electrophoretic coating (CDC). The electrophoretic epoxy film, with a thickness of 38 ± 3 µm (measured using a QNIX 1500 instrument from Automation Dr. NIX, Germany), was coated on a 1.3 ± 0.01 mm thick 7075 aluminum alloy plate. The volume resistivity of the epoxy layer was 15 ± 0.5 MΩ·m (measured using a Mili-TO3 ohmmeter and ammeter from H.-P. FISCHER ELEKTRONIK GmbH & Co., Germany). The bonded sample was then placed in a laboratory oven at Binder GmbH, Germany, and cured at 70 ± 5 °C for at least 6 hours, allowing the precursor to transform into a rigid structure through the sol-gel process, thus obtaining a rigid hydrated silicate gel. The surface tension (adhesive) strength measured by PROCEQ DYNA Z16 is 4.06 MPa.

[0194] To confirm that the generated material maintained a non-solid state under SATP, a sample of the material was loaded into a mold (150 mm cube, prepared according to EN 12390-1:2000) and stored for 28 days under standard ambient temperature and pressure (SATP, 25°C, 100,000 kPa / 1 bar). After being unloaded from the mold, the sample was placed on a flat surface of the stage. Over the next 19 hours, the sample lost its cubic shape.

[0195] Example 14

[0196] To estimate the application efficiency of the alkali metal hydrosilicate (silicate precursor) of the present invention for fire retardation, two dry spruce branches with needles, each weighing 10 ± 0.1 g, were selected. The branches were coated with the material prepared according to Example 10 – Sample No. 10.3 by immersion and storage in a laboratory oven at Binder GmbH (Germany) at 65 ± 5 °C for at least 6 hours to convert the precursor material into a rigid form based on a sol-gel process, thereby obtaining a rigid hydrosilicate gel on the surface of the sample. Both samples were treated using a POWER MAPP high-performance welding apparatus (Rothenberger Industrial, Germany) at an operating temperature of 1250 °C.

[0197] Untreated samples were burned with a strong flame for 30 seconds. Treated samples failed to ignite even after being treated with a torch for 60 seconds. The flame did not propagate on the surface of the treated branches.

[0198] Therefore, the high application efficiency of the material according to the invention for fire protection has been confirmed.

[0199] Example 15

[0200] To estimate the efficiency of the alkali metal hydrosilicate (silicate precursor) of the present invention in the application of a method for preventing thermal runaway, two modules of a rechargeable battery were fabricated. The first module was made of three rows of continuously positioned lithium-ion rechargeable batteries (Panasonic). All batteries were fully charged and continuously connected. Furthermore, the module was tightly inserted into a plastic box made of LDPE with a wall thickness of 2 mm.

[0201] The second module was manufactured in the same manner; however, over 90% of the free space inside the compartment between the batteries was filled with alkali metal hydrosilicate (silicate precursor) obtained according to Example 1. The module filled with the material according to the invention was stored under SATP for 10 days.

[0202] Subsequently, at least one battery in each module was struck by a sharp metal bar on the side to mechanically initiate the thermal runaway process. Untreated modules burned out within 5 minutes. In treated modules, sparking was observed during the initial 5 seconds, and then all thermal processes within the module (represented by the evaporation of vapor) were completed over the next 5 minutes.

[0203] Therefore, the high efficiency of the material according to the invention in preventing thermal runaway processes has been demonstrated.

[0204] Unless otherwise stated, any quantity expressed as a percentage or parts is by weight and, in doubt, refers to the total weight of the composition / mixture involved. The characterization of numerical values ​​as “approximately,” “about,” and similar expressions means including values ​​up to 10%, preferably up to 5%, and in any case at least 1%, with the exact value being the most preferred value or limit.

[0205] The term "substantially free" means that the specific material is not intentionally added to the composition and is present only in trace amounts or as an impurity. As used herein, unless otherwise indicated, the term "free" means that the composition does not contain the specific material, i.e., the composition contains 0 wt% of such material.

Claims

1. An alkali metal hydrosilicate, having a chemical elemental composition (wt%) after heat treatment at 250±5°C for 30 minutes±1 minute: Silicon 27-40; Aluminum 0.9-3.5; Iron 0.2-3.5; Calcium 0.2-2.0; Magnesium 0.05-0.5; Alkali metals (sodium, potassium, or combinations thereof) 8.0–19.0; Oxygen 43-54; Other elements - not exceeding 3.0%, Based on XRF data.

2. The alkali metal hydrosilicate according to claim 1, characterized in that, The results show a weight loss of approximately 45 wt% to approximately 65 wt% as determined by a moisture analyzer after heat treatment at 250 °C ± 5 °C for 30 min ± 1 min.

3. The alkali metal hydrosilicate according to claim 1 or 2, characterized in that, It has a Pa range of approximately 100 to approximately 70,000 at a temperature of 25 ± 0.5 °C. s, preferably about 150-1600 Pa s, more preferably about 200 to about 1500 Pa The viscosity of s (measured by a Brinell viscometer).

4. The alkali metal hydrosilicate according to any one of claims 1 to 3, characterized in that, It has a pH value from about 10.2 to about 13, preferably from about 10.6 to about 12.

5. The alkali metal hydrosilicate according to any one of claims 1 to 4, characterized in that, It contains no more than 10 wt% of a liquid acidic component extracted by heating to a temperature of 70 ± 5 °C, evacuating to 0.1 bar within about 15 minutes, and maintaining the evacuation for about 6-8 hours.

6. The alkali metal hydrosilicate according to any one of claims 1 to 5, characterized in that, It does not harden after being stored at standard ambient temperature and pressure (SATP, 25 °C, 100,000 kPa / 1 bar) for at least 28 days.

7. A method for preparing an alkali metal hydrosilicate as defined in any one of claims 1 to 5, comprising the following steps: a) Provide a particulate silica raw material comprising at least 70% amorphous SiO2 and a dry particulate alkali metal hydroxide, and optionally adjust the moisture content of the silica raw material to at least about 70 wt% and not more than about 81.5 wt%; b) The granular silica raw material and the dry granular alkali metal hydroxide are mixed at a specific energy input of about 200 kJ / kg to 750 kJ / kg at a ratio of 1 part by weight of dry alkali metal hydroxide and 5.25 to 10.5 parts by weight of dry silica raw material, preferably in a stirrer at a speed of about 1000 to about 4000 rpm. c) Add water at a ratio of 1 part by weight of dry solid to 2.55 to 4.3 parts by weight of water, preferably under the mixing conditions of step b), to obtain a viscous product, and optionally adjust the amount of water based on the moisture content of the silica raw material used.

8. The method according to claim 8, wherein, The silica raw material is selected from sedimentary rocks, such as diatomite, diatomaceous earth, diatomite rock, platy siliceous rock, sponge rock, radiolarian rock, opal, and industrial by-products of amorphous silica.

9. The method according to claim 7 or 8, wherein, The silica raw material is selected from The following is the composition of diatomaceous earth (Type 1): The following is a composition of diatomaceous earth (type 2): Amorphous silica byproducts (microsilica powder) produced from ferroalloys of the following composition: 。 10. The method according to any one of claims 7 to 9, wherein, The dried particulate alkali metal hydroxide is selected from sodium hydroxide, potassium hydroxide, or a combination thereof.

11. The method according to any one of claims 7 to 10, wherein, In step c), water is added at a temperature of about 75 °C to about 95 °C, preferably about 75 °C to about 85 °C.

12. The method according to any one of claims 7 to 11, further comprising the following steps: The viscosity of the obtained product is reduced by diluting it with water until the diluted material reaches a pH of at least 8.

13. An alkali metal hydrosilicate, which can be obtained by the method of any one of claims 7 to 12 or by the method of any one of claims 7 to 12.

14. Use of any alkali metal hydrosilicate according to any one of claims 1 to 6 and 13 in the preparation of hydrated silicate gels and silicate solids for fire protection, prevention of thermal runaway and production of cellulose-based composite materials.

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