Composite asbestos-free board and preparation method thereof

Abstract

The invention belongs to the field of building materials, and discloses a composite asbestos-free board and a preparation method thereof, the composite asbestos-free board is prepared from the following raw materials by weight: 50-70 parts of a composite inorganic base material, 10-20 parts of a natural modified binder, 5-15 parts of a function regulator, and 8-12 parts of water; the composite inorganic base material is a compound of red mud and talcum powder, and the natural modified binder is a compound of konjac glucomannan and guar gum; the function regulator comprises nano silicon dioxide sol and sodium citrate; the invention aims to overcome the defects in the prior art and provides a composite asbestos-free board and a preparation method thereof. The asbestos-free board takes red mud and other industrial wastes as main raw materials, and is matched with the natural modified binder and the function regulator, so that the asbestos-free board has the characteristics of high strength, good toughness, excellent waterproof performance and the like, and the preparation process is simple and stable and meets the environmental protection requirement.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a composite asbestos-free board and its preparation method. Background Technology

[0002] Asbestos boards were once widely used in the construction industry due to their excellent fire resistance, heat insulation, and sound insulation properties. However, asbestos fibers are highly carcinogenic, and long-term exposure can cause serious diseases such as lung cancer and mesothelioma. Many countries have explicitly banned the production and use of asbestos materials. Therefore, the development of asbestos-free alternatives has become an inevitable trend in the industry.

[0003] Currently, the main types of asbestos-free boards on the market are as follows: cement-based asbestos-free cement boards, which have high strength but poor toughness, are prone to cracking, and have poor waterproof performance, making them susceptible to moisture and deformation in humid environments; gypsum-based asbestos-free gypsum boards, which have good fire resistance but low strength and poor water resistance, and can only be used in dry environments; and plant fiber-reinforced asbestos-free boards, which have good environmental performance but insufficient aging resistance, and are prone to performance degradation with long-term use.

[0004] There are still many problems in the current preparation process of asbestos-free boards: First, traditional organic binders such as urea-formaldehyde resin and phenolic resin are often used. These binders release harmful gases such as formaldehyde during production and use, which are not environmentally friendly and have high costs. Second, some asbestos-free boards use industrial waste such as fly ash and slag as raw materials. However, due to the imperfect waste pretreatment process and the lack of effective dealkali removal and impurity removal, the product performance fluctuates greatly, and the strength and stability are difficult to guarantee. Third, problems such as uneven mixing of slurry, improper control of molding pressure, and unreasonable curing system in the preparation process further affect the overall performance of asbestos-free boards.

[0005] Furthermore, existing asbestos-free boards also have functional shortcomings, such as insufficient antibacterial and mildew-resistant properties, making them prone to bacterial and mold growth in humid environments, affecting safety and durability. At the same time, the production efficiency of existing asbestos-free boards is low, and energy consumption is high, which does not align with the development concept of green manufacturing. Based on these realities, there is an urgent need to develop a composite asbestos-free board with superior performance, good environmental performance, stable manufacturing process, and diverse functions. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a composite asbestos-free board and its preparation method. This asbestos-free board uses industrial waste such as red mud as the main raw material, combined with natural modified binders and functional regulators, and features high strength, good toughness, and excellent waterproof performance. Furthermore, the preparation process is simple and stable, and meets environmental protection requirements.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The technical solution provided by this invention is: a composite asbestos-free board, made from the following raw materials in parts by weight: 50-70 parts of composite inorganic substrate, 10-20 parts of natural modified binder, 5-15 parts of functional regulator, and 8-12 parts of water; The composite inorganic substrate is a mixture of red mud and talc powder, wherein the mass ratio of red mud to talc powder is 3-4:1, the red mud has a loss on ignition of ≤5% after pretreatment, a fineness of ≤10% residue on a 0.08mm square hole sieve, and the whiteness of the talc powder is ≥90% with a particle size of 10-20μm. The natural modified binder is a compound of modified konjac glucomannan and guar gum, with a mass ratio of 2-3:1. The modified konjac glucomannan is konjac glucomannan that has been cross-linked with epichlorohydrin. The functional modifiers include nano-silica sol and sodium citrate, with a mass ratio of nano-silica sol to sodium citrate of 3-4:1.

[0008] Further, the red mud pretreatment method is as follows: mix red mud and water at a mass ratio of 1:3-5, stir for 30-60 minutes, let stand for sedimentation for 2-4 hours, discard the supernatant, repeat the operation until the pH of the leachate is ≤9; after filtration, dry the filter cake in a forced-air drying oven at 105-110℃ for 12-24 hours, and then ball mill it at a speed of 300-400 r / min for 2-3 hours until the fineness meets the standard.

[0009] Furthermore, the preparation method of modified konjac glucomannan is as follows: Konjac glucomannan is dissolved in deionized water to prepare a solution with a mass fraction of 5-8%. The pH is adjusted to 8-9 with 10% sodium hydroxide solution. Epichlorohydrin is added at a mass fraction of 3-5% of konjac glucomannan. The mixture is stirred in a constant temperature water bath at 60-70℃ at a speed of 200-300 r / min for 2-3 hours. After the reaction, the pH is adjusted to 7 with 10% hydrochloric acid. After spray drying, the mixture is pulverized to 80-100 mesh to obtain the product. The spray drying inlet air temperature is 180-200℃ and the outlet air temperature is 80-90℃.

[0010] Furthermore, the nano-silica sol has a particle size of 20-40 nm, a solid content of 25-35 wt%, and a pH value of 8-9. It is an acidic silica sol that has been neutralized to this pH range with ammonia water.

[0011] Furthermore, the composite inorganic substrate also includes 5-10 parts by weight of mica powder, the aspect ratio of which is 50-80:1, and the mica powder is a layered structure prepared by wet grinding.

[0012] This invention also provides a method for preparing a composite asbestos-free board, comprising the following steps: S1: Substrate activation: Mix the pretreated red mud with talc powder, add 0.5-1% of the mass of the composite inorganic substrate with silane coupling agent KH-570 (pre-diluted with ethanol to a mass fraction of 10%), and stir in a high-speed mixer at a speed of 800-1000 r / min for 15-20 min for surface activation. During the stirring process, the material temperature is controlled at 40-50℃. S2: Binder preparation: Mix modified konjac glucomannan and guar gum in proportion, add 3-5 times the weight of 50-60℃ deionized water, stir in an electric stirrer (speed 300-400r / min) until completely dissolved, and keep warm at 50℃ for later use. S3: Slurry preparation: Add the activated composite inorganic substrate to a dual-blade mixer and dry mix for 5-10 minutes (blade speed 200-300 r / min). Add the natural modified binder solution and 50% by weight of water, adjust the blade speed to 400-500 r / min and mix for 15-20 minutes. Then add the functional regulator and the remaining water and continue mixing for 25-35 minutes until the slurry is uniform. The slurry temperature is controlled at 30-40℃. S4: Vacuum forming: Inject the slurry into a steel mold with vent holes (size customized according to product requirements), degas it in a vacuum drying oven at a vacuum degree of -0.07 to -0.08 MPa for 1-2 minutes, then transfer it to a flat vulcanizing machine, pressurize it to 8-12 MPa at a pressurization rate of 1-2 MPa / min, press it at a pressing temperature of 45-55℃, and hold it for 5-7 minutes; S5: Gradient curing: Place the molded blank in a constant temperature and humidity curing chamber and cure it for 16-20 hours at 50-60℃ and 75-80% relative humidity. Then, raise the temperature to 75-85℃ at a rate of 2-4℃ / h and adjust the relative humidity to 50-60% to continue curing for 20-28 hours. In the later stage of curing, turn on the blower in the chamber (wind speed 1-2m / s). After cooling to room temperature, sand it with a sander (sandpaper grit 120-180) to obtain the final product.

[0013] Furthermore, the S1 medium-high speed mixer has Z-shaped impellers with a gap of 5-10mm between the impeller and the cylinder.

[0014] Furthermore, in the S3, the blades of the dual-blade agitator are installed in a staggered manner with an included angle of 90°.

[0015] Furthermore, during the curing process in S5, the billet is turned over every 8 hours, and a high-temperature resistant silicone pad is used for support during the turning process.

[0016] The beneficial effects of this technical solution are: (1) This invention uses a composite inorganic substrate of red mud and talc powder. The red mud has stable properties after pretreatment and works synergistically with talc powder to improve the strength and hardness of the board. The addition of mica powder can enhance the toughness and flexural strength of the board and reduce cracking. In the natural modified binder, konjac glucomannan has significantly improved bonding performance after being cross-linked with epichlorohydrin. When combined with guar gum, it can further improve the integrity and stability of the board. In the functional regulator, nano silica sol can fill the internal pores of the board, improve density and strength, and sodium citrate can regulate the fluidity of the slurry and improve molding performance. The synergistic effect of the two makes the asbestos-free board have high strength, high toughness, good waterproof performance and durability.

[0017] (2) This invention uses industrial waste such as red mud as the main raw material, realizing the resource utilization of industrial waste, reducing solid waste pollution, and lowering production costs. The use of natural modified binders instead of traditional organic binders avoids the release of harmful gases such as formaldehyde, meeting environmental protection requirements. The preparation process has low energy consumption and no toxic or harmful substances are emitted, conforming to the development concept of green manufacturing.

[0018] (3) The present invention has carried out strict pretreatment of red mud, and ensured the stability of raw materials by water washing and dealkalization, drying and ball milling. The substrate activation step uses silane coupling agent to treat the surface of inorganic substrate, which improves the compatibility between inorganic substrate and organic binder. The uniformity of slurry is ensured by controlling stirring speed, time and temperature during slurry preparation. Vacuum forming and gradient curing process can make the internal structure of the board dense, the performance stable, and the repeatability good, which is suitable for industrial production.

[0019] (4) The present invention can adjust the raw material ratio and process parameters according to actual needs to prepare asbestos-free boards with different properties. For example, by increasing the amount of nano silica sol, the strength and wear resistance of the board can be improved. By adding antibacterial agents, the board can be given antibacterial and mildew-proof properties, thus expanding its application range.

[0020] (5) The preparation process of the present invention is simple, convenient to operate, the parameters of each step are clear and easy to control, the production cycle is short, and the production efficiency can be improved and the production cost can be reduced. Attached Figure Description

[0021] Figure 1 This is a performance comparison parameter table of a composite asbestos-free board and its preparation method proposed in this invention; Figure 2 A comparative table of component differences of a composite asbestos-free board and its preparation method proposed in this invention; Figure 3 This is a comparative table showing the differences in the preparation methods of a composite asbestos-free board proposed in this invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The specific implementation process is as follows: Example 1: Please see Figure 1-3 The present invention provides a technical solution: a composite asbestos-free board, which is made from the following raw materials by actual weight: 50kg of composite inorganic substrate, 10kg of natural modified binder, 5kg of functional regulator, and 8kg of water; The composite inorganic substrate is a mixture of red mud and talc powder, with a mass ratio of red mud to talc powder of 3:1. After pretreatment, the red mud has a loss on ignition of 4% and a fineness of 8% on a 0.08mm square hole sieve. The talc powder has a whiteness of 91% and a particle size of 10-15μm. The natural modified binder is a compound of konjac glucomannan and guar gum in a mass ratio of 2:1. The konjac glucomannan is cross-linked and modified with epichlorohydrin. The epichlorohydrin crosslinking modification method for the above-mentioned konjac glucomannan is as follows: Konjac glucomannan powder was dissolved in deionized water to prepare a 5% (w / w) solution. The solution was stirred at 200 rpm in a 30°C constant temperature water bath until completely dissolved. The pH was adjusted to 8.5 with 10% sodium hydroxide solution. Epichlorohydrin (pre-diluted to 20% concentration with anhydrous ethanol) at 3% (w / w) of the konjac glucomannan mass was slowly added dropwise at a rate of 1 mL / min. During the addition process, the temperature was maintained at 60°C and the stirring speed at 300 rpm. After the addition was completed, the reaction was continued for 2 hours. During this period, the viscosity was measured every 15 minutes. The reaction was terminated when the viscosity reached 3 times the initial value. After the reaction was completed, the pH was adjusted to 7 with 10% hydrochloric acid solution. The solution was then spray-dried (inlet air temperature 180°C, outlet air temperature 85°C) to obtain cross-linked modified konjac glucomannan, which was then pulverized to 80 mesh for later use. The functional modifiers include nano-silica sol and sodium citrate in a mass ratio of 3:1. The nano-silica sol has a particle size of 20-25 nm, a solid content of 25 wt%, and a pH value of 8-8.5. The sodium citrate is commercially available analytical grade. The composite inorganic substrate also includes 5 kg of mica powder, with a diameter-to-thickness ratio of 50-60:1, which is a layered mica powder prepared by wet grinding. The preparation method of the above-mentioned composite asbestos-free board includes the following steps: S1: Substrate activation: Mix the pretreated red mud with talc powder, add 0.5% of the mass of the composite inorganic substrate with silane coupling agent KH-570 (pre-diluted with ethanol to a mass fraction of 10%), and stir in a high-speed mixer at 800 r / min for 15 min for surface activation. During the stirring process, the material temperature is controlled at 40-45℃. The stirring paddle of the high-speed mixer is a Z-shaped blade, and the gap between the blade and the cylinder is 5-6 mm. S2: Binder preparation: Mix modified konjac glucomannan and guar gum in proportion, add 3 times the weight of 50-55℃ deionized water, stir in an electric stirrer (300r / min) until completely dissolved, and keep warm at 50℃ for later use. S3: Slurry preparation: Add the activated composite inorganic substrate to the dual-blade mixer and dry mix for 5 minutes (blade speed 200 r / min). Add the natural modified binder solution and 50% water by weight, adjust the blade speed to 400 r / min and mix for 15 minutes. Then add the functional regulator and the remaining water and continue mixing for 25 minutes until the slurry is uniform. The slurry temperature is controlled at 30-35℃. The blades of the dual-blade mixer are installed in a staggered manner with an included angle of 90°. S4: Vacuum forming: Inject the slurry into a steel mold with vent holes, degas it in a vacuum drying oven at a vacuum degree of -0.07MPa for 1 minute, and then transfer it to a flat vulcanizing machine. Pressurize it to 8MPa at a pressurization rate of 1MPa / min, pressurize it at a temperature of 45-50℃, and hold it for 5 minutes. S5: Gradient curing: Place the formed blank in a constant temperature and humidity curing chamber and cure it for 16 hours at 50-55℃ and 75-78% relative humidity. Then, increase the temperature to 75-80℃ at a rate of 2℃ / h and adjust the relative humidity to 50-55% to continue curing for 20 hours. In the later stage of curing, turn on the blower in the chamber (wind speed 1m / s). During the curing process, turn the blank over once every 8 hours. Use a high-temperature resistant silicone pad to support it when turning it over. After cooling to room temperature, sand it with a sander (sandpaper grit 120) to obtain the final product. The composite asbestos-free board prepared in this embodiment uses red mud and talc powder as composite inorganic substrates, realizing the resource utilization of industrial waste and reducing production costs; by adding mica powder, the toughness and flexural strength of the board are improved; the use of natural modified binder ensures the bonding performance of the board and has good environmental protection; the addition of functional regulators further improves the comprehensive performance of the board; all performance indicators meet the basic requirements of building materials.

[0024] Example 2: Please see Figure 1-3The present invention provides a technical solution: a composite asbestos-free board, which is made from the following raw materials by actual weight: 60kg of composite inorganic substrate, 15kg of natural modified binder, 10kg of functional regulator, and 10kg of water. The composite inorganic substrate is a mixture of red mud and talc powder, with a mass ratio of red mud to talc powder of 3.5:1. After pretreatment, the red mud has a loss on ignition of 3.5% and a fineness of 7% on a 0.08mm square hole sieve. The talc powder has a whiteness of 92% and a particle size of 15-20μm. The natural modified binder is a compound of konjac glucomannan and guar gum in a mass ratio of 2.5:1. The konjac glucomannan is cross-linked and modified with epichlorohydrin. The epichlorohydrin crosslinking modification method for the above-mentioned konjac glucomannan is the same as that in Example 1.

[0025] The functional modifiers include nano-silica sol and sodium citrate in a mass ratio of 3.5:1. The nano-silica sol has a particle size of 25-30 nm, a solid content of 30 wt%, and a pH value of 8.5-9. The sodium citrate is commercially available analytical grade. The composite inorganic substrate also includes 7 kg of mica powder, with a diameter-to-thickness ratio of 60-70:1, which is a layered mica powder prepared by wet grinding. The preparation method of the above-mentioned composite asbestos-free board includes the following steps: S1: Substrate activation: Mix the pretreated red mud with talc powder, add 0.8% of the mass of the composite inorganic substrate of silane coupling agent KH-570 (pre-diluted with ethanol to a mass fraction of 10%), and stir in a high-speed mixer at 900 r / min for 18 min for surface activation. During the stirring process, the material temperature is controlled at 45-50℃. The stirring paddle of the high-speed mixer is a Z-shaped blade, and the gap between the blade and the cylinder is 7-8 mm. S2: Binder preparation: Mix modified konjac glucomannan and guar gum in proportion, add 4 times the weight of 55-60℃ deionized water, stir in an electric stirrer (speed 350r / min) until completely dissolved, and keep warm at 50℃ for later use. S3: Slurry preparation: Add the activated composite inorganic substrate to the dual-blade mixer and dry mix for 8 minutes (blade speed 250 r / min). Add the natural modified binder solution and 50% water by weight, adjust the blade speed to 450 r / min and mix for 18 minutes. Then add the functional regulator and the remaining water and continue mixing for 30 minutes until the slurry is uniform. The slurry temperature is controlled at 35-40℃. The blades of the dual-blade mixer are installed in a staggered manner with an included angle of 90°. S4: Vacuum forming: Inject the slurry into a steel mold with vent holes, degas it in a vacuum drying oven at a vacuum degree of -0.075MPa for 1.5min, then transfer it to a flat vulcanizing machine, pressurize it to 10MPa at a pressurization rate of 1.5MPa / min, pressurize it at a temperature of 50-55℃, and hold it for 6min. S5: Gradient curing: Place the formed blank in a constant temperature and humidity curing chamber and cure it for 18 hours at 55-60℃ and 78-80% relative humidity. Then, increase the temperature to 80-85℃ at a rate of 3℃ / h and adjust the relative humidity to 55-60% to continue curing for 24 hours. In the later stage of curing, turn on the blower in the chamber (wind speed 1.5m / s). During the curing process, turn the blank over once every 8 hours. Use a high-temperature resistant silicone pad for support when turning over. After cooling to room temperature, sand it with a sander (150 grit sandpaper) to obtain the final product. Based on Example 1, this embodiment adjusts the ratio of raw materials and the preparation process parameters; increases the amount of composite inorganic substrate and functional regulator, improving the strength and functionality of the board; optimizes parameters such as stirring time, pressing pressure and curing time, making the raw materials more uniformly mixed, the board structure more compact, and the performance more stable; the overall performance of the prepared asbestos-free board is better than that of Example 1.

[0026] Example 3: Please see Figure 1-3 The present invention provides a technical solution: a composite asbestos-free board, which is made from the following raw materials by actual weight: 65kg of composite inorganic substrate, 18kg of natural modified binder, 12kg of functional regulator, and 11kg of water. The composite inorganic substrate is a mixture of red mud and talc powder, with a mass ratio of red mud to talc powder of 3.8:1. After pretreatment, the red mud has a loss on ignition of 4.5% and a fineness of 9% on a 0.08mm square hole sieve. The talc powder has a whiteness of 93% and a particle size of 18-20μm. The natural modified binder is a compound of konjac glucomannan and guar gum in a mass ratio of 2.8:1. The konjac glucomannan is cross-linked and modified with epichlorohydrin. The epichlorohydrin crosslinking modification method for the above-mentioned konjac glucomannan is the same as that in Example 1.

[0027] The functional modifiers include nano-silica sol and sodium citrate in a mass ratio of 3.8:1. The nano-silica sol has a particle size of 35-40 nm, a solid content of 32 wt%, and a pH value of 8.5-9. The sodium citrate is commercially available analytical grade. The composite inorganic substrate also includes 8 kg of mica powder, with a diameter-to-thickness ratio of 70-80:1, which is a layered mica powder prepared by wet grinding. The preparation method of the above-mentioned composite asbestos-free board includes the following steps: S1: Substrate activation: Mix the pretreated red mud with talc powder, add 0.8% of the mass of the composite inorganic substrate of silane coupling agent KH-570 (pre-diluted with ethanol to a mass fraction of 10%), and stir in a high-speed mixer at 950 r / min for 18 min for surface activation. During the stirring process, the material temperature is controlled at 45-50℃. The stirring paddle of the high-speed mixer is a Z-shaped blade, and the gap between the blade and the cylinder is 8-9 mm. S2: Binder preparation: Mix modified konjac glucomannan and guar gum in proportion, add 4.5 times the weight of 55-60℃ deionized water, stir in an electric stirrer (speed 380r / min) until completely dissolved, and keep warm at 50℃ for later use; S3: Slurry preparation: Add the activated composite inorganic substrate to the dual-blade mixer and dry mix for 8 minutes (blade speed 280 r / min). Add the natural modified binder solution and 50% by weight of water, adjust the blade speed to 480 r / min and mix for 18 minutes. Then add the functional regulator and the remaining water and continue mixing for 32 minutes until the slurry is uniform. The slurry temperature is controlled at 35-40℃. The blades of the dual-blade mixer are installed in a staggered manner with an included angle of 90°. S4: Vacuum forming: The slurry is injected into a steel mold with vent holes, degassed in a vacuum drying oven at a vacuum degree of -0.08MPa for 1.8min, and then transferred to a flat vulcanizing machine, pressurized to 11MPa at a pressurization rate of 1.8MPa / min, with a pressing temperature of 50-55℃ and a holding time of 6.5min. S5: Gradient curing: Place the formed blank in a constant temperature and humidity curing chamber and cure it for 19 hours at 55-60℃ and 78-80% relative humidity. Then, raise the temperature to 80-85℃ at a rate of 3.5℃ / h and adjust the relative humidity to 55-60% to continue curing for 26 hours. In the later stage of curing, turn on the blower in the chamber (wind speed 1.8m / s). Turn the blank over every 8 hours during the curing process. Use a high-temperature resistant silicone pad for support when turning over. After cooling to room temperature, sand it with a sander (160 grit sandpaper) to obtain the final product. This embodiment further increases the amount of composite inorganic substrate, natural modified binder, and functional regulator, and optimizes process parameters such as stirring speed and pressing pressure. The higher amount of substrate ensures the structural stability of the board, the increased amount of binder makes the board more integral, and the reasonable ratio of functional regulator further improves the strength and waterproof performance of the board. The prepared asbestos-free board shows excellent performance in key indicators such as flexural strength, compressive strength, and water absorption.

[0028] Example 4: Please see Figure 1-3The present invention provides a technical solution: a composite asbestos-free board, which is made from the following raw materials by actual weight: 70 kg of composite inorganic substrate, 20 kg of natural modified binder, 15 kg of functional regulator, and 12 kg of water. The composite inorganic substrate is a mixture of red mud and talc powder, with a mass ratio of red mud to talc powder of 4:1. After pretreatment, the red mud has a loss on ignition of 5% and a fineness of 10% residue on a 0.08mm square hole sieve. The talc powder has a whiteness of 94% and a particle size of 15-20μm. The natural modified binder is a compound of konjac glucomannan and guar gum in a mass ratio of 3:1. The konjac glucomannan is cross-linked and modified with epichlorohydrin. The epichlorohydrin crosslinking modification method for the above-mentioned konjac glucomannan is the same as that in Example 1.

[0029] The functional modifiers include nano-silica sol and sodium citrate in a mass ratio of 4:1. The nano-silica sol has a particle size of 30-40 nm, a solid content of 35 wt%, and a pH value of 8.5-9. The sodium citrate is commercially available analytical grade. The composite inorganic substrate also includes 10 kg of mica powder, with a diameter-to-thickness ratio of 75-80:1, which is a layered mica powder prepared by wet grinding. The preparation method of the above-mentioned composite asbestos-free board includes the following steps: S1: Substrate activation: Mix the pretreated red mud with talc powder, add 1% of the mass of the composite inorganic substrate of silane coupling agent KH-570 (pre-diluted with ethanol to a mass fraction of 10%), and stir at 1000 r / min for 20 min in a high-speed mixer for surface activation. During the stirring process, the material temperature is controlled at 45-50℃. The stirring paddle of the high-speed mixer is a Z-shaped blade, and the gap between the blade and the cylinder is 9-10 mm. S2: Binder preparation: Mix modified konjac glucomannan and guar gum in proportion, add 5 times the weight of 55-60℃ deionized water, stir in an electric stirrer (speed 400r / min) until completely dissolved, and keep warm at 50℃ for later use. S3: Slurry preparation: Add the activated composite inorganic substrate to the dual-blade mixer and dry mix for 10 minutes (blade speed 300 r / min). Add the natural modified binder solution and 50% water by weight, adjust the blade speed to 500 r / min and mix for 20 minutes. Then add the functional regulator and the remaining water and continue mixing for 35 minutes until the slurry is uniform. The slurry temperature is controlled at 35-40℃. The blades of the dual-blade mixer are installed in a staggered manner with an included angle of 90°. S4: Vacuum forming: Inject the slurry into a steel mold with vent holes, degas it in a vacuum drying oven at a vacuum degree of -0.08MPa for 2 minutes, and then transfer it to a flat vulcanizing machine. Pressurize it to 12MPa at a pressurization rate of 2MPa / min, pressurize it at a temperature of 50-55℃, and hold it for 7 minutes. S5: Gradient curing: Place the formed green body in a constant temperature and humidity curing chamber and cure it for 20 hours at 55-60℃ and 78-80% relative humidity. Then, increase the temperature to 80-85℃ at a rate of 4℃ / h and adjust the relative humidity to 55-60% to continue curing for 28 hours. In the later stage of curing, turn on the blower in the chamber (wind speed 2m / s). During the curing process, turn the green body over once every 8 hours. Use a high-temperature resistant silicone pad to support it when turning it over. After cooling to room temperature, sand it with a sander (sandpaper grit 180) to obtain the final product. This embodiment uses the highest proportion of raw materials and optimized process parameters, with the highest amount of composite inorganic substrate to ensure the high strength of the board; the largest amount of natural modified adhesive to further enhance the board's bonding performance and integrity; and the largest amount of functional regulator to effectively improve the board's density and waterproof performance. Through high-strength pressing and thorough curing, the internal structure of the board becomes more compact, achieving optimal performance and meeting the requirements of applications with high strength and durability.

[0030] Example 5: Please see Figure 1-3 The present invention provides a technical solution: a composite asbestos-free board, which is made from the following raw materials by actual weight: 55kg composite inorganic substrate, 12kg natural modified binder, 8kg functional regulator, and 9kg water; The composite inorganic substrate is a mixture of red mud and talc powder, with a mass ratio of red mud to talc powder of 3.2:1. After pretreatment, the red mud has a loss on ignition of 3.8% and a fineness of 7% on a 0.08mm square hole sieve. The talc powder has a whiteness of 91.5% and a particle size of 12-18μm. The natural modified binder is a compound of konjac glucomannan and guar gum in a mass ratio of 2.2:1. The konjac glucomannan is cross-linked and modified with epichlorohydrin. The epichlorohydrin crosslinking modification method for the above-mentioned konjac glucomannan is the same as that in Example 1.

[0031] The functional modifiers include nano-silica sol and sodium citrate in a mass ratio of 3.2:1. The nano-silica sol has a particle size of 22-30 nm, a solid content of 28 wt%, and a pH of 8-8.5. The sodium citrate is commercially available analytical grade. The composite inorganic substrate also includes 6 kg of mica powder, with a diameter-to-thickness ratio of 55-65:1, which is a layered mica powder prepared by wet grinding. The preparation method of the above-mentioned composite asbestos-free board includes the following steps: S1: Substrate activation: Mix the pretreated red mud with talc powder, add 0.6% of the mass of the composite inorganic substrate of silane coupling agent KH-570 (pre-diluted with ethanol to a mass fraction of 10%), and stir in a high-speed mixer at 850 r / min for 16 min for surface activation. During the stirring process, the material temperature is controlled at 42-47℃. The stirring paddle of the high-speed mixer is a Z-shaped blade, and the gap between the blade and the cylinder is 6-7 mm. S2: Binder preparation: Mix modified konjac glucomannan and guar gum in a certain proportion, add 3.5 times the weight of 52-57℃ deionized water, stir in an electric stirrer (speed 320r / min) until completely dissolved, and keep warm at 50℃ for later use; S3: Slurry preparation: Add the activated composite inorganic substrate to the dual-blade mixer and dry mix for 6 minutes (blade speed 220 r / min). Add the natural modified binder solution and 50% by weight of water, adjust the blade speed to 420 r / min and mix for 16 minutes. Then add the functional regulator and the remaining water and continue mixing for 28 minutes until the slurry is uniform. The slurry temperature is controlled at 32-37℃. The blades of the dual-blade mixer are installed in a staggered manner with an included angle of 90°. S4: Vacuum forming: The slurry is injected into a steel mold with vent holes, degassed in a vacuum drying oven at a vacuum degree of -0.072MPa for 1.2min, and then transferred to a flat vulcanizing machine, pressurized to 9MPa at a pressurization rate of 1.2MPa / min, with a pressing temperature of 46-52℃ and a holding time of 5.5min. S5: Gradient curing: Place the formed blank in a constant temperature and humidity curing chamber and cure it for 17 hours at 52-57℃ and 76-79% relative humidity. Then, increase the temperature to 76-82℃ at a rate of 2.5℃ / h and adjust the relative humidity to 52-57% to continue curing for 22 hours. In the later stage of curing, turn on the blower in the chamber (wind speed 1.2m / s). During the curing process, turn the blank over once every 8 hours. Use a high-temperature resistant silicone pad for support when turning over. After cooling to room temperature, sand it with a sander (130 grit sandpaper) to obtain the final product. This embodiment uses a medium to low raw material ratio and relatively mild process parameters. By reasonably controlling the ratio of red mud to talc powder, the amount of binder, and the ratio of functional regulators, the production cost is reduced while ensuring the basic performance of the board. The optimization of slurry preparation and molding process parameters makes the raw materials mixed evenly and the board structure stable, which is suitable for general construction scenarios where cost is more sensitive.

[0032] Example 6: Please see Figure 1-3The present invention provides a technical solution: a composite asbestos-free board, made from the following raw materials by actual weight: 62kg composite inorganic substrate, 16kg natural modified binder, 10kg functional regulator, and 10.5kg water; The composite inorganic substrate is a mixture of red mud and talc powder, with a mass ratio of red mud to talc powder of 3.6:1. After pretreatment, the red mud has a loss on ignition of 4.2% and a fineness of 8.5% on a 0.08mm square hole sieve. The talc powder has a whiteness of 92.5% and a particle size of 14-20μm. The natural modified binder is a compound of konjac glucomannan and guar gum in a mass ratio of 2.6:1. The konjac glucomannan is cross-linked and modified with epichlorohydrin. The epichlorohydrin crosslinking modification method for the above-mentioned konjac glucomannan is the same as that in Example 1.

[0033] The functional modifiers include nano-silica sol and sodium citrate in a mass ratio of 3.6:1. The nano-silica sol has a particle size of 28-35 nm, a solid content of 31 wt%, and a pH value of 8.2-8.8. The sodium citrate is commercially available analytical grade. The composite inorganic substrate also includes 9 kg of mica powder, with a diameter-to-thickness ratio of 65-75:1, which is a layered mica powder prepared by wet grinding. The preparation method of the above-mentioned composite asbestos-free board includes the following steps: S1: Substrate activation: Mix the pretreated red mud with talc powder, add 0.9% of the mass of the composite inorganic substrate of silane coupling agent KH-570 (pre-diluted with ethanol to a mass fraction of 10%), and stir at 950 r / min for 19 min in a high-speed mixer for surface activation. During the stirring process, the material temperature is controlled at 44-48℃. The stirring paddle of the high-speed mixer is a Z-shaped blade, and the gap between the blade and the cylinder is 8-9 mm. S2: Binder preparation: Mix modified konjac glucomannan and guar gum in proportion, add 4.2 times the weight of 54-58℃ deionized water, stir in an electric stirrer (360r / min) until completely dissolved, and keep warm at 50℃ for later use; S3: Slurry preparation: Add the activated composite inorganic substrate to the dual-blade mixer and dry mix for 9 minutes (blade speed 270 r / min). Add the natural modified binder solution and 50% water by weight, adjust the blade speed to 460 r / min and mix for 17 minutes. Then add the functional regulator and the remaining water and continue mixing for 32 minutes until the slurry is uniform. The slurry temperature is controlled at 34-38℃. The blades of the dual-blade mixer are installed in a staggered manner with an included angle of 90°. S4: Vacuum forming: The slurry is injected into a steel mold with vent holes, degassed in a vacuum drying oven at a vacuum degree of -0.078MPa for 1.7min, and then transferred to a flat vulcanizing machine, pressurized to 10.5MPa at a pressurization rate of 1.7MPa / min, with a pressing temperature of 48-53℃ and a holding time of 6.2min. S5: Gradient curing: Place the formed blank in a constant temperature and humidity curing chamber and cure it for 18.5 hours at 53-58℃ and 77-79% relative humidity. Then, increase the temperature to 78-83℃ at a rate of 3.2℃ / h and adjust the relative humidity to 54-58% to continue curing for 25 hours. In the later stage of curing, turn on the blower in the chamber (wind speed 1.6m / s). Turn the blank over every 8 hours during the curing process. Use a high-temperature resistant silicone pad for support when turning over. After cooling to room temperature, sand it with a sander (160 grit sandpaper) to obtain the final product. This embodiment uses a medium-to-high raw material ratio and sets relatively precise process parameters. By optimizing the red mud pretreatment process and substrate activation parameters, the activity and compatibility of the inorganic substrate are improved. The reasonable ratio of binder and functional modifier achieves a balance between strength, toughness and waterproof performance of the board. The precise control of the gradient curing process further reduces the internal stress of the board and lowers the risk of cracking, making it suitable for building scenarios with high requirements for comprehensive performance.

[0034] Comparative Example 1 Please see Figure 1-3 The present invention provides a comparative technical solution: an asbestos-free board, made from the following raw materials by actual weight: 60 kg of composite inorganic substrate (using only red mud, without adding talc), 15 kg of natural modified binder, 10 kg of functional regulator, and 10 kg of water. The red mud, after pretreatment, had a loss on ignition of 3.5% and a fineness of 7% on a 0.08mm square-hole sieve. The types and parameters of the natural modified binder and functional regulator were the same as in Example 2. The composite inorganic substrate also included 7kg of mica powder. The preparation method is the same as in Example 2, except that no talc powder was added to the substrate. This comparative example did not add talc powder and used only red mud as the inorganic substrate. Compared with Example 2, the strength and toughness of the board decreased significantly, the flexural strength decreased by about 20%, the compressive strength decreased by about 15%, and the surface smoothness was poor. The reason is that the lack of talc powder resulted in an unreasonable particle size distribution of the substrate, which could not form a dense structure. At the same time, the lack of lubrication effect of talc powder reduced the fluidity of the slurry and affected the molding effect.

[0035] Comparative Example 2 Please see Figure 1-3The present invention provides a comparative technical solution: an asbestos-free board, made from the following raw materials by actual weight: 60 kg of composite inorganic substrate, 15 kg of binder (using unmodified konjac glucomannan, without the addition of guar gum), 10 kg of functional regulator, and 10 kg of water. The types and parameters of the composite inorganic substrate are the same as in Example 2; the types and parameters of the functional modifier are the same as in Example 2; the composite inorganic substrate also includes 7 kg of mica powder; The preparation method is the same as in Example 2, except that the binder is unmodified konjac glucomannan; This comparative example uses unmodified konjac glucomannan as a binder and does not add guar gum. Compared with Example 2, the bonding performance of the board is significantly reduced, the flexural strength is reduced by about 25%, and the board is prone to delamination. The reason is that the unmodified konjac glucomannan has insufficient bonding force and lacks the synergistic thickening effect of guar gum, resulting in poor slurry stability and poor overall board integrity.

[0036] Comparative Example 3 Please see Figure 1-3 The present invention provides a comparative technical solution: an asbestos-free board, made from the following raw materials by actual weight: 60 kg of composite inorganic substrate, 15 kg of natural modified binder, 10 kg of functional regulator (only nano silica sol is added, no sodium citrate is added), and 10 kg of water. The types and parameters of the composite inorganic substrate are the same as in Example 2; the types and parameters of the natural modified binder are the same as in Example 2; the composite inorganic substrate also includes 7 kg of mica powder; The preparation method is the same as in Example 2, except that sodium citrate was not added as the functional regulator. This comparative example did not add sodium citrate, but only used nano silica sol as a functional regulator. Compared with Example 2, the fluidity of the slurry decreased significantly, and clumping was prone to occur during the stirring process. The porosity of the molded board increased by about 10%, and the water absorption rate increased by about 15%. The reason is that the lack of sodium citrate makes it impossible to effectively adjust the pH value and dispersibility of the slurry. The nano silica sol is prone to agglomeration and cannot fully play its filling role, which affects the density and waterproof performance of the board.

[0037] Please see Figure 1-3 : Through a systematic comparative analysis of six embodiments and three comparative examples, it can be clearly found that the composite asbestos-free board technology proposed in this invention overcomes many defects in the prior art in terms of raw material co-design, process parameter optimization and performance improvement. From the perspective of the synergistic effect of the raw material system, this invention forms a multiphase synergistic enhancement material system by scientifically compounding inorganic substrates, natural modified binders, and functional regulators. This design concept is fundamentally different from existing technologies. In Examples 1-6, red mud and talc powder are compounded at a mass ratio of 3-4:1 as inorganic substrates. The red mud undergoes strict pretreatment (washing and dealkalization to pH≤9, ball milling to 0.08mm square hole sieve residue≤10%), effectively solving the problems of high impurity content and low activity of red mud. The introduction of talc powder fills the gaps between red mud particles through particle size distribution optimization, and at the same time improves the fluidity of the slurry by utilizing its layered structure. Comparative Example 1 did not add talc powder and used only red mud as the inorganic substrate, resulting in a decrease of about 20% in flexural strength and about 15% in compressive strength of the board, as well as poor surface smoothness, which fully demonstrates the synergistic effect of red mud and talc powder. The necessity of compounding powders; In terms of the bonding system, the example uses epichlorohydrin-modified konjac glucomannan and guar gum in a 2-3:1 ratio. The modified konjac glucomannan forms a three-dimensional network structure through cross-linking reaction, and its synergistic effect with guar gum significantly improves the bonding strength and water resistance. Comparative Example 2 uses unmodified konjac glucomannan and no guar gum is added. The board shows obvious delamination and the flexural strength decreases by about 25%, highlighting the creative value of the adhesive modification and compounding technology. The 3-4:1 ratio design of nano silica sol and sodium citrate in the functional regulator also reflects the synergistic advantage. Nano silica fills the pores and improves the density, while sodium citrate adjusts the pH value of the slurry and optimizes the dispersibility. The lack of sodium citrate in Comparative Example 3 leads to severe slurry agglomeration and an increase in water absorption rate of about 15%, further verifying the effectiveness of this synergistic mechanism. The preparation process of this invention solves the technical problems of uneven slurry mixing, loose structure, and large performance fluctuations in the prior art by synergistically optimizing core processes such as substrate activation, gradient pressing, and precise curing. In the substrate activation step, the example uses silane coupling agent KH-570 to modify the surface of the inorganic substrate (the amount is 0.5-1% of the substrate mass). The substrate is stirred in a high-speed mixer at 800-1000 r / min for 15-20 min, so that the coupling agent molecules form chemical bonds with the hydroxyl groups on the surface of red mud and talc, which significantly improves the interfacial compatibility between the inorganic and organic phases. Compared with the direct mixing method in the traditional process, this technology increases the interfacial bonding strength of the board by about 30%, effectively reducing the risk of delamination. In the vacuum forming stage, vacuum degassing at -0.07 to -0.08 MPa is used for 1-2 minutes. Gradient pressurization at MPa / min (final pressure 8-12MPa) effectively removes air bubbles from the slurry, increasing the density of the board by 15-20%. In contrast, the board without vacuum degassing in the comparative example showed a significant increase in internal porosity. The gradient curing process is another major innovation of this invention. First, curing at 50-60℃ and 75-80% relative humidity for 16-20 hours promotes initial cross-linking of the adhesive. Then, the temperature is increased to 75-85℃ at a rate of 2-4℃ / h, and the humidity is adjusted to 50-60% for another 20-28 hours. By precisely controlling the temperature and humidity gradient, stress concentration within the board is reduced, and the cracking rate is lowered to below 5%. Compared with the single curing system in existing technologies, this process design improves the dimensional stability of the board by more than 25%, fully demonstrating the significant progress brought about by process optimization. From a systematic comparison of performance data, the composite asbestos-free board of the present invention comprehensively surpasses the comparative examples and existing technologies in key performance indicators. Regarding mechanical properties, Example 4 (highest raw material ratio) achieves a flexural strength of 18.5 MPa and a compressive strength of 65 MPa, representing increases of 35% and 40% respectively compared to Comparative Example 1 (without talc), and increases of 42% and 45% respectively compared to Comparative Example 2 (without modified binder). Even Example 1 with the lowest ratio achieves flexural and compressive strengths of 12.8 MPa and 48 MPa respectively, meeting the high-level requirements of GB / T23451-2009 "Lightweight Partition Wall Panels for Buildings". In terms of durability, Example 2 has a water absorption rate of only... The strength loss rate is 8.5%, which is 40% lower than that of Comparative Example 3 (without sodium citrate). After 200 freeze-thaw cycles, the strength loss rate is less than 10%, which is far lower than the 15-20% loss rate of existing asbestos-free boards. In terms of environmental performance, this invention uses industrial waste such as red mud (accounting for 75-80% of the inorganic substrate), realizing the resource utilization of solid waste. In terms of production efficiency, by optimizing process parameters, the curing cycle of this invention is shortened by 20-30% compared with traditional processes, and energy consumption is reduced by about 15%, which is in line with the concept of green manufacturing. These performance advantages not only prove the creativity of this technical solution, but also highlight its application value and promotion prospects in the field of building materials, providing a new technical path for the development of asbestos-free alternative materials.

[0038] The test method is as follows: Flexural strength test: The test was conducted in accordance with GB / T7019-2014 "Test Methods for Fiber Cement Products"; 250mm×50mm×10mm specimens were cut from the asbestos-free boards prepared in the examples and comparative examples, and at least 5 specimens were prepared for each test group; Before the test, the specimens were cured in an environment of (23±2)℃ and (50±5)% relative humidity for 24h; A three-point bending test device was used, with a span of 200mm and a loading rate of (5±1)mm / min, and the maximum load at which the specimen broke was recorded; 1.2 Compressive strength test; Compressive strength test: The test was conducted according to GB / T17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)"; the sample size was 40mm×40mm×40mm, and 6 samples were prepared for each group. After curing in an environment of (23±2)℃ and (50±5)% relative humidity for 24h, the samples were loaded using a cement mortar compressive strength tester. The loading rate was controlled at (2400±200)N / s, and the maximum pressure at which the sample failed was recorded.

[0039] Interface bonding strength test: The interface bonding strength was determined by the splitting test method; a layered sample with a size of 100mm×100mm×20mm was prepared (simulating the interface between the inorganic and organic phases inside the plate), and a vertical pressure was applied to the center of the sample along the interface direction at a loading rate of (2±0.5)mm / min. The maximum load when the interface separated was recorded. Water absorption test: The test shall be conducted in accordance with GB / T17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels"; the sample size shall be (50±1) mm × (50±1) mm × original thickness, and at least 5 samples shall be tested in each group; before the test, the sample shall be dried in a forced-air drying oven at (103±2)℃ to constant weight (the interval between two weighings shall be 2h, and the mass difference shall not exceed 0.02g), and after being taken out, it shall be placed in a desiccator to cool to room temperature, and the dried mass m1 shall be weighed (accurate to 0.01g); the sample shall be completely immersed in distilled water at (23±2)℃, and the water level shall be at least 20mm above the sample. After soaking for (24±1)h, the sample shall be taken out, and the surface moisture of the sample shall be gently wiped off with a wrung-out damp towel. The mass m2 after water absorption shall be weighed immediately (accurate to 0.01g); the water absorption rate shall be calculated according to the formula W=(m2-m1) / m1×100%, and the arithmetic mean of 5 samples shall be taken as the test result, and the result shall be retained to one decimal place. Freeze-thaw cycle test: The rapid freezing method was carried out according to GB / T50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete"; the sample size was 100mm×100mm×100mm, with 3 samples per group; after soaking the samples in water at (23±2)℃ for 4 days, they were placed in a freeze-thaw test chamber, frozen at -18℃ for 4 hours, and then thawed in water at 20℃ for 4 hours, which constituted one cycle; a total of 200 cycles were carried out, and the mass loss rate and strength loss rate of the samples were measured after every 50 cycles; the mass loss rate was calculated according to the formula Δm=(m0-mn) / m0×100%, where m0 is the initial mass and mn is the mass after n cycles; the strength loss rate was calculated according to the formula Δσ=(σ0-σn) / σ0×100%, where σ0 is the initial strength and σn is the strength after n cycles; Water resistance test: The sample with dimensions of 100mm×100mm×10mm was immersed in distilled water at (23±2)℃ for 7 days, and its flexural strength retention rate was measured after it was taken out.

[0040] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific technical solutions or characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A composite asbestos-free board, characterized in that, It is made from the following raw materials in parts by weight: 50-70 parts of composite inorganic matrix, 10-20 parts of natural modified binder, 5-15 parts of functional modifier, and 8-12 parts of water; The composite inorganic substrate is a mixture of red mud and talc powder, wherein the mass ratio of red mud to talc powder is 3-4:1, the red mud has a loss on ignition of ≤5% after pretreatment, a fineness of ≤10% residue on a 0.08mm square hole sieve, and the whiteness of the talc powder is ≥90% with a particle size of 10-20μm. The natural modified binder is a compound of modified konjac glucomannan and guar gum, with a mass ratio of 2-3:

1. The modified konjac glucomannan is konjac glucomannan that has been cross-linked with epichlorohydrin. The functional modifier includes nano-silica sol and sodium citrate, with a mass ratio of nano-silica sol to sodium citrate of 3-4:

1.

2. The composite non-asbestos plate according to claim 1, wherein The red mud pretreatment method is as follows: mix red mud and water at a mass ratio of 1:3-5, stir for 30-60 minutes, let stand for sedimentation for 2-4 hours, discard the supernatant, and repeat the operation until the pH of the leachate is ≤9; after filtration, dry the filter cake in a forced-air drying oven at 105-110℃ for 12-24 hours, and then ball mill it at a speed of 300-400r / min for 2-3 hours until the fineness meets the standard.

3. The composite non-asbestos plate according to claim 1, wherein The modified konjac glucomannan is prepared by dissolving konjac glucomannan in deionized water to prepare a solution with a mass fraction of 5-8%. The pH is adjusted to 8-9 with 10% sodium hydroxide solution. Epichlorohydrin is added at a mass fraction of 3-5% of the konjac glucomannan. The mixture is stirred in a constant temperature water bath at 60-70℃ at a speed of 200-300 r / min for 2-3 hours. After the reaction, the pH is adjusted to 7 with 10% hydrochloric acid. The mixture is then spray-dried and pulverized to 80-100 mesh. The spray drying inlet temperature is 180-200℃ and the outlet temperature is 80-90℃.

4. The composite non-asbestos plate according to claim 1, wherein The nano-silica sol has a particle size of 20-40 nm, a solid content of 25-35 wt%, and a pH value of 8-9. It is an acidic silica sol that has been neutralized to this pH range with ammonia water.

5. The composite non-asbestos plate according to claim 1, wherein The composite inorganic substrate also includes 5-10 parts by weight of mica powder, the mica powder having a diameter-to-thickness ratio of 50-80:1, and being a layered mica powder prepared by wet grinding.

6. A method of producing a composite non-asbestos sheet according to any one of claims 1 to 5, characterized by, Includes the following steps: S1: Substrate activation: Mix the pretreated red mud with talc powder, add 0.5-1% of the mass of the composite inorganic substrate with silane coupling agent KH-570 (pre-diluted with ethanol to a mass fraction of 10%), and stir in a high-speed mixer at a speed of 800-1000 r / min for 15-20 min for surface activation. During the stirring process, the material temperature is controlled at 40-50℃. S2: Binder preparation: Mix modified konjac glucomannan and guar gum in proportion, add 3-5 times the weight of 50-60℃ deionized water, stir at 300-400r / min with an electric stirrer until completely dissolved, and keep warm at 50℃ for later use. S3: Slurry preparation: Add the activated composite inorganic substrate to a dual-blade mixer and dry mix for 5-10 minutes, with the blade speed at 200-300 r / min. Add the natural modified binder solution and 50% by weight of water, adjust the blade speed to 400-500 r / min and mix for 15-20 minutes. Then add the functional regulator and the remaining water and continue mixing for 25-35 minutes until the slurry is uniform. The slurry temperature is controlled at 30-40℃. S4: Vacuum forming: Inject the slurry into a steel mold with vent holes, degas it in a vacuum drying oven at a vacuum degree of -0.07 to -0.08 MPa for 1-2 minutes, and then transfer it to a flat vulcanizing machine. Pressurize it to 8-12 MPa at a pressurization rate of 1-2 MPa / min, press it at a temperature of 45-55℃, and hold it for 5-7 minutes. S5: Gradient curing: Place the molded blank in a constant temperature and humidity curing chamber and cure it for 16-20 hours at 50-60℃ and 75-80% relative humidity. Then, raise the temperature to 75-85℃ at a rate of 2-4℃ / h and adjust the relative humidity to 50-60% to continue curing for 20-28 hours. In the later stage of curing, turn on the blower in the chamber with a wind speed of 1-2m / s. After cooling to room temperature, sand it with a sander with a sandpaper grit of 120-180.

7. The preparation method according to claim 6, characterized in that, The stirring blade of the high-speed mixer in S1 is a Z-shaped blade, and the gap between the blade and the cylinder is 5-10mm.

8. The preparation method according to claim 6, characterized in that, The blades of the dual-blade agitator in S3 are installed in a staggered manner with an included angle of 90°.

9. The preparation method according to claim 6, characterized in that, During the curing process in S5, the billet is turned over once every 8 hours, and a high-temperature resistant silicone pad is used for support during the turning process.

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