A fiber-reinforced composite environmental protection building formwork and its preparation method

Abstract

The present invention discloses a fiber-reinforced composite environmental protection building formwork and a preparation method thereof, belonging to the technical field of building formwork processing, and is used to solve the technical problem that the mechanical properties, heat insulation and fire retardant properties of the fiber-reinforced composite building formwork in the prior art need to be further improved; the present invention can reduce environmental pollution and waste of resources by reusing rice husks and rice straws as reinforcing fibers, which conforms to the concept of green buildings and sustainable development, and uses aerogel micropowder and composite flame retardant particles as reinforcing materials to reinforce the modified fibers, and uses polypropylene and crosslinking reinforcing agents as organic adhesives. Under the action of an initiator, it promotes the establishment of crosslinked bonds of molecular bonds between the molecules of the building formwork, while improving the overall mechanical properties of the building formwork, it further improves the heat insulation and fire retardant properties, water resistance and alkali resistance of the building formwork material.

Description

Technical Field

[0001] The present invention relates to the technical field of building formwork processing, and particularly relates to a fiber-reinforced composite environmental protection building formwork and a preparation method thereof. Background Art

[0002] A building formwork is a temporary support structure, which is made according to design requirements to form concrete structures and components in accordance with specified positions and geometric dimensions, and bears the self-weight of the building formwork and the external loads acting thereon. Traditional building formworks are mainly made of materials such as wood and steel. Although wood formworks have certain strength and workability, due to the long growth cycle of wood, extensive use of wood easily leads to over-cutting of forest resources, causing damage to the environment. And steel formworks have high strength and durability, but are heavy in weight, inconvenient for handling and installation. At the same time, the production process of steel consumes high energy and also has a certain impact on the environment.

[0003] With the global emphasis on green buildings and sustainable development, as an important auxiliary material in building construction, the performance requirements for building formworks in terms of environmental protection, mechanical strength, durability, etc. are increasing day by day. Traditional building formworks such as wood formworks have problems such as large resource consumption, easy damage, and non-environmental protection. And new environmental protection materials such as rice husks and rice straws, due to their rich renewable resources and unique physical and chemical properties, have gradually attracted attention and are applied to the preparation of building formworks.

[0004] Rice husks and rice straws, as agricultural wastes, have the advantages of large yield, low cost, and renewable. In recent years, through technological innovation, scientific researchers have transformed fiber materials such as rice husks and rice straws into high-performance composite materials for the preparation of building formworks, and made remarkable progress. However, rice husks and rice straws consist of an epidermis layer with strong water absorption and a shell layer with relatively low water absorption in the inner layer. They have strong water absorption and do not have alkali resistance themselves, resulting in the building formworks made of them being prone to water absorption and deformation during building use, and the mechanical stability of the building formworks is poor. For traditional fiber-reinforced building formworks, the fibers and resins are usually directly mixed and then cast. The cross-linking degree between the components of the building formworks is poor, and the mechanical strength of the building formworks needs to be further improved. Moreover, the heat insulation and fire retardant properties of existing composite building formwork materials also need to be improved urgently. Summary of the Invention

[0005] The purpose of the present invention is to provide a fiber-reinforced composite environmental protection building formwork and a preparation method thereof, which are used to solve the technical problems that the mechanical properties, heat insulation and fire retardant properties of fiber-reinforced composite building formworks in the prior art need to be further improved.

[0006] The object of the present invention can be achieved by the following technical solutions: A fiber-reinforced composite environmental protection building formwork, comprising the following components by weight: 80-100 parts of polypropylene, 20-30 parts of a crosslinking enhancer, 30-50 parts of aerogel micropowder, 80-100 parts of modified fibers, 30-40 parts of composite flame retardant particles, 2-3 parts of an initiator, and 4-6 parts of an auxiliary additive;

[0007] The crosslinking enhancer is obtained by the following steps:

[0008] A1. Add 4-aminobenzenethiol, absolute ethanol, and formaldehyde solution to a reaction kettle and stir. Raise the temperature of the reaction kettle to 60-70 °C, keep the temperature for 6-8 h, and perform post-treatment to obtain triphenylthiol triazine;

[0009] The synthesis reaction formula of triphenylthiol triazine is:

[0010]

[0011] The synthesis reaction principle of triphenylthiol triazine is:

[0012] Under heating conditions, the aldehyde group of formaldehyde undergoes a nucleophilic substitution reaction with the amino group on 4-aminobenzenethiol. As the reaction proceeds, the product further cyclizes to form a triazine structure, and triphenylthiol triazine modified with triphenylthiol is prepared. Its mass spectrometry analysis data is: m / z: 411.0898 (100.0%), 412.0931 (22.7%), 413.0856 (13.6%), 414.0889 (3.1%), 413.0965 (2.5%), 412.0891 (2.4%), 412.0868 (1.1%).

[0013] A2. Add triphenylthiol triazine, isophorone diisocyanate, and toluene to a reaction kettle protected by nitrogen and stir. Raise the temperature of the reaction kettle to 50-60 °C, add a catalyst to the reaction kettle, keep the temperature for 3-4 h, add 5-methyl-2-(1-methylethenyl)-4-hexen-1-ol to the reaction kettle, and keep the temperature for 4-5 h, and perform post-treatment to obtain the crosslinking enhancer.

[0014] The synthesis reaction formula of the crosslinking enhancer is:

[0015]

[0016]

[0017] In the formula:

[0018] The synthesis reaction principle of the crosslinking enhancer is:

[0019] The mercapto group on triphenylthiophenetriazine undergoes a condensation reaction with the isocyanate group on isophorone diisocyanate. By controlling the dosage ratio of the reactants and taking advantage of the difference in the reaction activities of the two isocyanate groups on isophorone diisocyanate, an intermediate modified with an isocyanate group end is prepared. The isocyanate group on the intermediate further undergoes a condensation reaction with the alcohol hydroxyl group on 5-methyl-2-(1-methylethenyl)-4-hexen-1-ol to prepare a crosslinking enhancer modified with multiple unsaturated olefin double bonds.

[0020] Furthermore, the initiator is benzoyl peroxide, and the auxiliary additive is composed of an antioxidant, a dispersant, a flame retardant, and a plasticizer in a weight ratio of 1:2:3:2. The antioxidant is one or more of antioxidant 168, antioxidant 1010, and antioxidant 1076. The dispersant is one or more of sodium stearate, calcium stearate, zinc stearate, and magnesium stearate. The flame retardant is one or more of tributyl phosphate, tris(2-ethylhexyl) phosphate, tris(2-chloroethyl) phosphate, tris(2,3-dichloropropyl) phosphate, and tris(2,3-dibromopropyl) phosphate. The plasticizer is phthalate.

[0021] Furthermore, in step A1, the dosage ratio of 4-aminothiophenol, absolute ethanol, and formaldehyde solution is 1 g:6 mL:3 - 5 g. The mass fraction of the formaldehyde solution is 30 - 37%. The post-treatment includes: after the reaction is completed, the temperature of the reaction kettle is kept at 60 - 70 °C, the solvent is removed by reduced pressure distillation. Dichloromethane and purified water are added to the reaction kettle, stirred for 20 - 30 min, left to stand for liquid separation. The organic phase is dried with anhydrous magnesium sulfate for 40 - 60 min and then transferred to a rotary evaporator with a water bath temperature of 40 - 50 °C, and dichloromethane is removed by reduced pressure distillation to obtain triphenylthiophenetriazine. In step A2, the molar ratio of triphenylthiophenetriazine, isophorone diisocyanate, and 5-methyl-2-(1-methylethenyl)-4-hexen-1-ol is 1:3:3. The dosage ratio of isophorone diisocyanate, toluene, and the catalyst is 1 g:5 mL:0.01 g. The catalyst is dibutyltin diacetate. The post-treatment includes: after the reaction is completed, the temperature of the reaction kettle is raised to 70 - 80 °C, and toluene is removed by reduced pressure distillation to obtain the crosslinking enhancer.

[0022] Furthermore, the preparation method of the aerogel micropowder is as follows: Aluminum sec-butoxide and isopropanol are added to the reaction kettle and stirred until the system is dissolved. The temperature of the reaction kettle is raised to 70 - 80 °C. Dilute nitric acid is added to the reaction kettle, and the reaction is kept warm for 2 - 3 h. Tetraethyl orthosilicate and allyltriethoxysilane are added to the reaction kettle, and the mixture is stirred and kept warm for 2 - 3 h, left to stand and age for 8 - 10 h, and the aerogel micropowder is obtained by post-treatment.

[0023] The synthesis reaction principle of the aerogel micropowder is:

[0024] After aluminum sec-butoxide is dissolved in isopropyl alcohol solvent, with the addition of dilute nitric acid, a hydrolysis reaction occurs to generate aluminum hydroxide and sec-butanol. The hydrolysis products will further undergo a polycondensation reaction to form colloidal small particles bonded by aluminum-oxygen bonds. These small particles gradually grow and crosslink to form a gel with a three-dimensional network structure. Tetraethyl orthosilicate and allyl triethoxysilane are used as silicon sources and added to the reaction system. They will also undergo hydrolysis and polycondensation reactions to generate colloidal particles bonded by silicon-oxygen bonds. The hydrolysis products of the silicon source and the hydrolysis products of the aluminum source further crosslink to form an alumina-silica composite gel network. After curing, washing, and drying, an aluminum / silicon composite aerogel micropowder is prepared.

[0025] Furthermore, the dosage ratio of aluminum sec-butoxide, isopropyl alcohol, dilute nitric acid, tetraethyl orthosilicate, and allyl triethoxysilane is 3 - 5 g: 30 - 50 mL: 5 - 7 mL: 8 - 10 g: 2 - 3 g. The concentration of the dilute nitric acid is 0.8 - 1.3 mol / L. The post-treatment includes: after the reaction is completed, the temperature of the reaction kettle is kept at 70 - 80 °C, the solvent is removed by reduced pressure distillation, the temperature of the reaction kettle is lowered to room temperature, absolute ethanol is added to the reaction kettle, stirred and dispersed for 50 - 60 min, allowed to stand, the upper clear liquid is separated, the lower solid is centrifuged and dried, and then transferred to a drying oven at 60 - 70 °C and dried to a constant weight to obtain the aerogel micropowder.

[0026] Furthermore, the modified fiber is processed by the following steps:

[0027] B1. Add rice husks and rice straw into a crusher and crush them into fiber powder with a particle size of 5 - 8 mm;

[0028] B2. Add the fiber powder and the activation liquid into a reaction kettle and stir. The temperature of the reaction kettle is raised to 70 - 80 °C and kept for reaction for 2 - 3 h, and then post-treated to obtain pretreated fiber;

[0029] B3. Add the pretreated fiber, absolute ethanol, and KH-570 into a reaction kettle and stir for 20 - 30 min. Add a 5 wt% sodium hydroxide solution into the reaction kettle, raise the temperature of the reaction kettle to 50 - 60 °C, and keep it for treatment for 3 - 4 h, and then post-treated to obtain the modified fiber.

[0030] The synthesis reaction principle of the modified fiber is as follows:

[0031] By crushing natural fibers such as rice husks and rice straw with a crusher to increase their surface area, and using the activation liquid to pretreat the fiber powder, the crystal structure of cellulose can be destroyed, the accessibility and reactivity of the fiber can be improved, creating favorable conditions for subsequent surface modification; on the basis of the pretreatment, under alkaline conditions, KH-570 is used to modify the surface of the fiber to form stable chemical bonds on the fiber surface, thereby introducing organic functional groups onto the fiber surface to prepare the modified fiber.

[0032] Further, in step B2, the dosage ratio of the fiber powder to the activation liquid is 1 g: 10 - 15 mL. The activation liquid consists of potassium hydroxide, urea, sodium dodecyl sulfate, 10 wt% hydrogen peroxide and purified water in a dosage ratio of 5 g: 2 g: 1 g: 30 g: 60 mL. The post-treatment includes: after the reaction is completed, the temperature of the reaction kettle is reduced to room temperature, suction filtration is carried out, the filter cake is washed with purified water until neutral and then dried by suction, the filter cake is transferred to a drying oven at a temperature of 60 - 70 °C, dried to a constant weight to obtain the pretreated fiber; in step B3, the dosage ratio of the pretreated fiber, absolute ethanol, KH-570 and 5 wt% sodium hydroxide solution is 5 g: 50 mL: 2 - 3 g: 10 mL. The post-treatment includes: after the reaction is completed, the temperature of the reaction kettle is reduced to room temperature, suction filtration is carried out, the filter cake is washed with purified water until neutral and then dried by suction, the filter cake is transferred to a drying oven at a temperature of 60 - 70 °C, dried to a constant weight to obtain the modified fiber.

[0033] Further, the composite flame retardant particles are processed by the following steps:

[0034] C1. Place the diatomite in a muffle furnace, raise the temperature of the muffle furnace to 450 - 500 °C, keep it warm for 3 - 4 h, and naturally cool it to room temperature to obtain the calcined powder;

[0035] C2. Add the calcined powder and phosphoric acid solution to the reaction kettle and stir. Raise the temperature of the reaction kettle to 70 - 80 °C, keep stirring for 30 - 40 min, add the urea solution to the reaction kettle, raise the temperature of the reaction kettle to the system reflux, keep reacting for 60 - 80 min, add the modification liquid to the reaction kettle, and post-treat to obtain the crude composite flame retardant particles;

[0036] C3. Transfer the crude composite flame retardant particles to a ball mill, set the rotation speed of the ball mill to 200 - 250 r / min, and ball mill for 30 - 40 min to obtain the composite flame retardant particles.

[0037] The synthesis reaction principle of the composite flame retardant particles is:

[0038] During the high-temperature roasting process of diatomite, organic impurities, moisture, and volatile substances in the diatomite can be removed, mineral phase transformation and structural rearrangement in the diatomite can be induced, the physical and chemical properties of the diatomite can be changed, the specific surface area, pore structure, surface energy, etc. of the diatomite can be improved, making it easier for phosphoric acid to penetrate into the interior of the diatomite and form phosphates with substances such as aluminum and urea, forming an interpenetrating loading effect in the diatomite. In an acidic environment, the siloxane bonds in the modifier solution hydrolyze and react with the active groups on the particle surface, forming a polyorganosiloxane coating modified with fluorinated segments and olefins on the outside of the particles. After ball milling and mixing in a ball mill, the crude composite flame-retardant particles are impacted and rubbed by the spheres rotating at high speed, and are gradually broken into smaller particles, promoting the mixing and uniform distribution among the particles, and obtaining the composite flame-retardant particles after preparation.

[0039] Further, in step C2, the dosage ratio of the roasted powder, phosphoric acid solution, urea solution, and modifier solution is 10 g: 20 mL: 10 mL: 5 g. The concentration of the phosphoric acid solution is 1.5 mol / L, the concentration of the urea is 3.2 mol / L. The modifier solution is composed of trifluorooctyltrimethoxysilane and allyltriethoxysilane in a weight ratio of 2:1. The post-treatment includes: after the reaction is completed, the reaction kettle is kept warm and refluxed, and the solution is removed by reduced pressure evaporation to obtain the crude composite flame-retardant particles.

[0040] The present invention also provides a preparation method of a fiber-reinforced composite environmental protection building formwork, comprising the following steps:

[0041] S1. Add aerogel micropowder, polypropylene, crosslinking enhancer, and auxiliary additive into a kneader. The temperature of the kneader is raised to 115 - 125 °C, and knead for 5 - 10 min. Then, add modified fiber and composite flame-retardant particles into the kneader in sequence, knead for 15 - 25 min, add an initiator into the kneader, knead for 40 - 60 min, and granulate to obtain a mixture.

[0042] S2. Spread the mixture flat in a flat vulcanizer. The temperature of the flat vulcanizer is raised to 140 - 150 °C, the pressure is raised to 12 - 16 MPa, keep warm and under pressure for 40 - 60 min, and discharge after cooling to room temperature to obtain the building formwork.

[0043] The present invention has the following beneficial effects:

[0044] 1. The fiber-reinforced composite environmentally friendly building formwork of the present invention uses rice husks and rice straws as agricultural waste as raw materials. After activating treatment and then surface modification treatment, modified fibers are prepared. Their reuse helps to reduce environmental pollution and resource waste. Using the modified rice husk and rice straw fibers as part of the building formwork conforms to the concept of green building and sustainable development. By using aerogel micropowder and composite flame retardant particles as reinforcing materials to reinforce the modified fibers, an enhanced system of aerogel micropowder, inorganic particles and fibers is formed. With polypropylene and cross-linking enhancer as organic binders, and under the action of initiators, intermolecular cross-linking bonds are promoted to establish among the molecules of the building formwork, improving the overall mechanical properties of the building formwork. By improving the fiber materials and then cooperating with aerogel micropowder and composite flame retardant particles, the heat insulation, flame retardant, water resistance and alkali resistance of the building formwork materials are further improved.

[0045] 2. The fiber-reinforced composite environmentally friendly building formwork of the present invention can reduce the penetration and adsorption of water molecules and lower the water absorption expansion of fibers by modifying the surface of the fiber powder. And the rice husk and rice straw fibers treated by activating treatment and using surface modifiers such as KH-570 can improve the interfacial compatibility between the fibers and the resin, making the two combine more closely. Aerogel micropowder has an extremely low density and high porosity, but its skeleton structure is extremely strong. When mixed with the modified fibers, the two can form complementary advantages to enhance the overall strength and stiffness of the building formwork. This enhanced mechanical property enables the formwork to withstand greater loads and reduce deformation caused by external forces during use. Moreover, aerogel micropowder has an extremely low thermal conductivity. When mixed with the modified fibers, it can significantly improve the heat insulation performance of the building formwork. The high porosity and skeleton structure of diatomite in the composite flame retardant particles help to form a heat insulation barrier to reduce heat transfer. The silane compound in the modifier solution may reduce the surface energy of diatomite through its unique chemical structure, such as fluorinated alkyl functional groups, which helps to reduce heat transfer on the surface of the material, and the inorganic particles have excellent waterproof performance, further improving the heat insulation and waterproof performance of the material.

[0046] 3. In the fiber-reinforced composite environmentally friendly building formwork of the present invention, when preparing aerogel micropowder and composite flame retardant particles, the raw material composition is optimized, olefin double bond modification is formed on the aerogel micropowder and composite flame retardant particles, and triphenylthiophenol triazine with triphenylthiophenol-modified triazine is prepared and then further condensed with the alcohol hydroxyl group on 5-methyl-2-(1-methylethenyl)-4-hexen-1-ol to prepare a cross-linking enhancer with polyunsaturated olefin double bond modification. Using polypropylene as an organic binder, a kneader is used to promote the mixing of aerogel micropowder, modified fibers, and composite flame retardant particles. Under the action of a free radical initiator, a free radical polymerization reaction is initiated to promote cross-linking between the molecules in the building formwork, enhancing the cohesion and structural stability of the building formwork material, thereby enhancing the mechanical properties of the material. The triazine structure introduced by the cross-linking enhancer serves as a nitrogen source, the aluminum source in the aerogel micropowder, and the phosphate in the composite flame retardant particle serves as a phosphorus source to form a synergistic flame retardant system in the building formwork, further improving the flame retardant performance of the building formwork. Detailed implementation mode

[0047] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0048] Example 1

[0049] This example provides a preparation method for a fiber-reinforced composite environmentally friendly building formwork, including the following steps:

[0050] S1. Prepare a cross-linking enhancer

[0051] Weigh: 100 g of 4-aminothiophenol, 600 mL of absolute ethanol, and 300 g of 30 wt% formaldehyde solution and add them to a reaction kettle for stirring. The temperature of the reaction kettle is raised to 60 °C and kept warm for 6 h. After the reaction is completed, the temperature of the reaction kettle is kept at 60 °C, and the solvent is removed by reduced pressure distillation. Add 600 mL of dichloromethane and 100 mL of purified water to the reaction kettle, stir for 20 min, let it stand for liquid separation, dry the organic phase with anhydrous magnesium sulfate for 40 min, and then transfer it to a rotary evaporator with a water bath temperature of 40 °C to remove dichloromethane by reduced pressure distillation to obtain triphenylthiophenol triazine;

[0052] Weigh: 41.2 g of triphenylthiophenol triazine, 66.7 g of isophorone diisocyanate and 333 mL of toluene, add them to a reaction kettle under nitrogen protection and stir. Raise the temperature of the reaction kettle to 50 °C, add 0.41 g of dibutyltin diacetate to the reaction kettle, keep the temperature for reaction for 3 h, add 50.5 g of 5-methyl-2-(1-methylethenyl)-4-hexen-1-ol to the reaction kettle, and keep the temperature for reaction for 4 h. After the reaction is completed, raise the temperature of the reaction kettle to 70 °C, distill off toluene under reduced pressure to obtain a crosslinking enhancer.

[0053] S2. Aerogel micropowder

[0054] Weigh: 30 g of aluminum sec-butoxide and 300 mL of isopropanol, add them to a reaction kettle and stir until the system is dissolved. Raise the temperature of the reaction kettle to 70 °C, add 50 mL of 0.8 mol / L dilute nitric acid to the reaction kettle, keep the temperature for reaction for 2 h, add 80 g of tetraethyl orthosilicate and 20 g of allyltriethoxysilane to the reaction kettle, keep stirring for 2 h, stand and age for 8 h. After the reaction is completed, keep the temperature of the reaction kettle at 70 °C, distill off the solvent under reduced pressure, lower the temperature of the reaction kettle to room temperature, add 500 mL of absolute ethanol to the reaction kettle, stir and disperse for 50 min, stand, separate the upper clear liquid, transfer the lower solid to a drying oven at 60 °C, and dry to constant weight to obtain aerogel micropowder.

[0055] S3. Preparation of modified fibers

[0056] Add rice husks and rice straw to a crusher and crush them into fiber powder with a particle size of 5 - 8 mm;

[0057] Mix potassium hydroxide, urea, sodium dodecyl sulfate, 10 wt% hydrogen peroxide and purified water in a dosage ratio of 5 g:2 g:1 g:30 g:60 mL to obtain an activation solution for standby;

[0058] Weigh: 100 g of fiber powder and 1000 mL of activation solution, add them to a reaction kettle and stir. Raise the temperature of the reaction kettle to 70 °C, keep the temperature for reaction for 2 h. After the reaction is completed, lower the temperature of the reaction kettle to room temperature, filter by suction, wash the filter cake with purified water until neutral and then filter it dry. Transfer the filter cake to a drying oven at 60 °C and dry to constant weight to obtain pretreated fibers;

[0059] Weigh: 50 g of pretreated fibers, 500 g of absolute ethanol, 20 g of KH-570, add them to a reaction kettle and stir for 20 min. Add 100 mL of 5 wt% sodium hydroxide solution to the reaction kettle, raise the temperature of the reaction kettle to 50 °C, keep the temperature for treatment for 3 h. After the reaction is completed, lower the temperature of the reaction kettle to room temperature, filter by suction, wash the filter cake with purified water until neutral and then filter it dry. Transfer the filter cake to a drying oven at 60 °C and dry to constant weight to obtain modified fibers.

[0060] S4. Preparation of composite flame retardant particles

[0061] Place the diatomite in a muffle furnace, raise the temperature of the muffle furnace to 450 °C, keep it warm for 3 h, and let it cool naturally to room temperature to obtain the calcined powder;

[0062] Mix trifluorooctyltrimethoxysilane and allyltriethoxysilane in a weight ratio of 2:1 to obtain the modification liquid;

[0063] Weigh: 100 g of the calcined powder, 200 mL of 1.5 mol / L phosphoric acid solution and add them to a reaction kettle and stir. Raise the temperature of the reaction kettle to 70 °C, keep it warm and stir for 30 min. Add 100 mL of 3.2 mol / L urea solution to the reaction kettle. Raise the temperature of the reaction kettle to the system reflux temperature, keep it warm and react for 60 min. Add 50 g of the modification liquid to the reaction kettle. After the reaction is completed, keep the reaction kettle warm and reflux, and distill off the solution under reduced pressure to obtain the crude composite flame retardant particles;

[0064] Transfer the crude composite flame retardant particles to a ball mill, set the rotation speed of the ball mill to 200 r / min, and ball mill for 30 min to obtain the composite flame retardant particles.

[0065] S5. Prepare the building formwork

[0066] Mix antioxidant 168, sodium stearate, tributyl phosphate and dibutyl phthalate evenly in a weight ratio of 1:2:3:2 to obtain the auxiliary additive;

[0067] Weigh by weight: 30 parts of aerogel micropowder, 80 parts of polypropylene, 20 parts of crosslinking enhancer and 4 parts of auxiliary additive and add them to a kneader. Raise the temperature of the kneader to 115 °C and knead for 5 min. Add 80 parts of modified fiber and 30 parts of composite flame retardant particles to the kneader in sequence, knead for 15 min. Add 2 parts of benzoyl peroxide to the kneader and knead for 40 min, then granulate to obtain the mixture;

[0068] Lay the mixture flat on a flat vulcanizer, raise the temperature of the flat vulcanizer to 140 °C, raise the pressure to 12 MPa, keep it warm and pressurized for 40 min, and discharge after cooling to room temperature to obtain the building formwork.

[0069] Example 2

[0070] This example provides a preparation method of a fiber-reinforced composite environmental protection building formwork, including the following steps:

[0071] S1. Prepare the crosslinking enhancer

[0072] Weigh: 100 g of 4-aminothiophenol, 600 mL of absolute ethanol and 400 g of 34 wt% formaldehyde solution are added to a reaction kettle and stirred. The temperature of the reaction kettle is raised to 65 °C, and the reaction is carried out under insulation for 7 h. After the reaction is completed, the temperature of the reaction kettle is kept at 65 °C, and the solvent is removed by distillation under reduced pressure. 600 mL of dichloromethane and 100 mL of purified water are added to the reaction kettle, stirred for 25 min, and left to stand for liquid separation. The organic phase is dried with anhydrous magnesium sulfate for 50 min and then transferred to a rotary evaporator with a water bath temperature of 45 °C, and dichloromethane is removed by distillation under reduced pressure to obtain triphenylthiophene triazine;

[0073] Weigh: 41.2 g of triphenylthiophene triazine, 66.7 g of isophorone diisocyanate and 333 mL of toluene are added to a reaction kettle protected by nitrogen and stirred. The temperature of the reaction kettle is raised to 55 °C, 0.41 g of dibutyltin diacetate is added to the reaction kettle, and the reaction is carried out under insulation for 3.5 h. 50.5 g of 5-methyl-2-(1-methylethenyl)-4-hexen-1-ol is added to the reaction kettle, and the reaction is carried out under insulation for 4.5 h. After the reaction is completed, the temperature of the reaction kettle is raised to 75 °C, and toluene is removed by distillation under reduced pressure to obtain a crosslinking enhancer.

[0074] S2. Aerogel micropowder

[0075] Weigh: 40 g of aluminum sec-butoxide and 400 mL of isopropyl alcohol are added to a reaction kettle and stirred until the system is dissolved. The temperature of the reaction kettle is raised to 75 °C, 60 mL of 1.0 mol / L dilute nitric acid is added to the reaction kettle, and the reaction is carried out under insulation for 2.5 h. 90 g of tetraethyl orthosilicate and 25 g of allyltriethoxysilane are added to the reaction kettle, and the mixture is stirred under insulation for 2.5 h and left to age for 9 h. After the reaction is completed, the temperature of the reaction kettle is kept at 75 °C, and the solvent is removed by distillation under reduced pressure. The temperature of the reaction kettle is lowered to room temperature, 500 mL of absolute ethanol is added to the reaction kettle, stirred and dispersed for 55 min, left to stand, and the upper clear liquid is separated. The lower solid is centrifuged and dried and then transferred to a drying oven at 65 °C and dried to a constant weight to obtain aerogel micropowder.

[0076] S3. Preparation of modified fiber

[0077] Rice husks and rice straw are added to a crusher and crushed into fiber powder with a particle size of 5 - 8 mm;

[0078] Potassium hydroxide, urea, sodium dodecyl sulfate, 10 wt% hydrogen peroxide and purified water are mixed evenly according to the dosage ratio of 5 g: 2 g: 1 g: 30 g: 60 mL to obtain an activation solution for standby;

[0079] Weigh: 100 g of fiber powder and 1250 mL of activation solution are added to a reaction kettle and stirred. The temperature of the reaction kettle is raised to 75 °C, and the reaction is carried out under insulation for 2.5 h. After the reaction is completed, the temperature of the reaction kettle is lowered to room temperature, and filtration is carried out. The filter cake is washed with purified water until neutral and then dried by suction. The filter cake is transferred to a drying oven at 65 °C and dried to a constant weight to obtain pretreated fibers.

[0080] Weigh: 50 g of pretreated fibers, 500 g of absolute ethanol, and 25 g of KH-570 are added to a reaction kettle and stirred for 25 min. 100 mL of 5 wt% sodium hydroxide solution is added to the reaction kettle. The temperature of the reaction kettle is raised to 55 °C, and the reaction is carried out under insulation for 3.5 h. After the reaction is completed, the temperature of the reaction kettle is lowered to room temperature, and filtration is carried out. The filter cake is washed with purified water until neutral and then dried by suction. The filter cake is transferred to a drying oven at 65 °C and dried to a constant weight to obtain modified fibers.

[0081] S4. Preparation of composite flame retardant particles

[0082] Diatomite is placed in a muffle furnace. The temperature of the muffle furnace is raised to 475 °C, and the reaction is carried out under insulation for 3.5 h. Then it is cooled naturally to room temperature to obtain calcined powder.

[0083] Tridecafluorooctyltrimethoxysilane and allyltriethoxysilane are mixed according to a weight ratio of 2:1 to obtain a modification solution.

[0084] Weigh: 100 g of calcined powder and 200 mL of 1.5 mol / L phosphoric acid solution are added to a reaction kettle and stirred. The temperature of the reaction kettle is raised to 75 °C, and stirring is carried out under insulation for 35 min. 100 mL of 3.2 mol / L urea solution is added to the reaction kettle. The temperature of the reaction kettle is raised to the reflux temperature of the system, and the reaction is carried out under insulation for 70 min. 50 g of the modification solution is added to the reaction kettle. After the reaction is completed, the reaction kettle is kept under reflux, and the solution is removed by reduced pressure evaporation to obtain crude composite flame retardant particles.

[0085] The crude composite flame retardant particles are transferred to a ball mill, and the rotation speed of the ball mill is set to 225 r / min, and ball milling is carried out for 35 min to obtain composite flame retardant particles.

[0086] S5. Preparation of building templates

[0087] Antioxidant 1010, calcium stearate, tris(2-ethylhexyl) phosphate, and dioctyl phthalate are mixed evenly according to a weight ratio of 1:2:3:2 to obtain an auxiliary additive.

[0088] Weigh by parts by weight: 40 parts of aerogel micropowder, 90 parts of polypropylene, 25 parts of crosslinking enhancer, and 5 parts of auxiliary additive are added to a kneader. The temperature of the kneader is raised to 120 °C and kneaded for 8 min. Then, 90 parts of modified fiber and 35 parts of composite flame retardant particles are successively added to the kneader and kneaded for 20 min. Next, 2.5 parts of benzoyl peroxide are added to the kneader and kneaded for 50 min, followed by granulation to obtain a mixture.

[0089] The mixture is spread out in a flat vulcanizing machine. The temperature of the flat vulcanizing machine is raised to 145 °C, the pressure is raised to 14 MPa, and heat and pressure are maintained for 50 min. After cooling to room temperature, the product is discharged to obtain a building formwork.

[0090] Example 3

[0091] This example provides a preparation method of a fiber-reinforced composite environmental protection building formwork, which includes the following steps:

[0092] S1. Preparation of crosslinking enhancer

[0093] Weigh: 100 g of 4-aminothiophenol, 600 mL of absolute ethanol, and 500 g of 37 wt% formaldehyde solution are added to a reaction kettle and stirred. The temperature of the reaction kettle is raised to 70 °C and kept warm for reaction for 8 h. After the reaction is completed, the temperature of the reaction kettle is kept at 70 °C, and the solvent is removed by reduced pressure distillation. Then, 600 mL of dichloromethane and 100 mL of purified water are added to the reaction kettle, stirred for 30 min, and left to stand for liquid separation. The organic phase is dried with anhydrous magnesium sulfate for 60 min and then transferred to a rotary evaporator with a water bath temperature of 50 °C, and dichloromethane is removed by reduced pressure distillation to obtain triphenylthiol triazine.

[0094] Weigh: 41.2 g of triphenylthiol triazine, 66.7 g of isophorone diisocyanate, and 333 mL of toluene are added to a reaction kettle protected by nitrogen and stirred. The temperature of the reaction kettle is raised to 60 °C, 0.41 g of dibutyltin diacetate is added to the reaction kettle, and the reaction is kept warm for 4 h. Then, 50.5 g of 5-methyl-2-(1-methylethenyl)-4-hexen-1-ol is added to the reaction kettle and the reaction is kept warm for 5 h. After the reaction is completed, the temperature of the reaction kettle is raised to 80 °C, and toluene is removed by reduced pressure distillation to obtain the crosslinking enhancer.

[0095] S2. Aerogel micropowder

[0096] Weigh: 50 g of aluminum sec-butoxide and 3500 mL of isopropanol are added to a reaction kettle and stirred until the system dissolves. The temperature of the reaction kettle is raised to 80 °C, 70 mL of 1.3 mol / L dilute nitric acid is added to the reaction kettle, and the reaction is carried out under insulation for 3 h. 100 g of tetraethyl orthosilicate and 30 g of allyltriethoxysilane are added to the reaction kettle, and the mixture is stirred under insulation for 3 h and then left to age for 10 h. After the reaction is completed, the temperature of the reaction kettle is kept at 80 °C, the solvent is removed by distillation under reduced pressure, the temperature of the reaction kettle is lowered to room temperature, 500 mL of absolute ethanol is added to the reaction kettle, and the mixture is stirred and dispersed for 60 min, then left to stand. The upper clear liquid is separated, and the lower solid is centrifuged and dried and then transferred to a drying oven at 70 °C and dried to a constant weight to obtain aerogel micropowder.

[0097] S3. Preparation of modified fibers

[0098] Rice husks and rice straw are added to a crusher and crushed into fiber powder with a particle size of 5 - 8 mm.

[0099] Potassium hydroxide, urea, sodium dodecyl sulfate, 10 wt% hydrogen peroxide and purified water are mixed evenly according to the dosage ratio of 5 g: 2 g: 1 g: 30 g: 60 mL to obtain an activation solution for standby.

[0100] Weigh: 100 g of fiber powder and 1500 mL of activation solution are added to a reaction kettle and stirred. The temperature of the reaction kettle is raised to 80 °C, and the reaction is carried out under insulation for 3 h. After the reaction is completed, the temperature of the reaction kettle is lowered to room temperature, and the mixture is filtered by suction. The filter cake is washed with purified water until neutral and then dried by suction. The filter cake is transferred to a drying oven at 70 °C and dried to a constant weight to obtain pretreated fibers.

[0101] Weigh: 50 g of pretreated fibers, 500 g of absolute ethanol and 30 g of KH-570 are added to a reaction kettle and stirred for 30 min. 100 mL of 5 wt% sodium hydroxide solution is added to the reaction kettle, and the temperature of the reaction kettle is raised to 60 °C, and the treatment is carried out under insulation for 4 h. After the reaction is completed, the temperature of the reaction kettle is lowered to room temperature, and the mixture is filtered by suction. The filter cake is washed with purified water until neutral and then dried by suction. The filter cake is transferred to a drying oven at 70 °C and dried to a constant weight to obtain modified fibers.

[0102] S4. Preparation of composite flame retardant particles

[0103] Diatomite is placed in a muffle furnace, the temperature of the muffle furnace is raised to 500 °C, and the treatment is carried out under insulation for 4 h, and then it is naturally cooled to room temperature to obtain calcined powder.

[0104] Tridecafluorooctyltrimethoxysilane and allyltriethoxysilane are mixed according to the weight ratio of 2:1 to obtain a modification solution.

[0105] Weigh: Add 100 g of roasted powder and 200 mL of 1.5 mol / L phosphoric acid solution into the reaction kettle and stir. Raise the temperature of the reaction kettle to 80 °C, keep stirring for 40 min. Add 100 mL of 3.2 mol / L urea solution into the reaction kettle, raise the temperature of the reaction kettle to the system reflux temperature, and keep reacting for 80 min. Add 50 g of modifier solution into the reaction kettle. After the reaction is completed, keep the reaction kettle at reflux temperature, remove the solution by reduced pressure evaporation to obtain the crude composite flame retardant particles;

[0106] Transfer the crude composite flame retardant particles to a ball mill, set the rotation speed of the ball mill to 250 r / min, and ball mill for 40 min to obtain the composite flame retardant particles.

[0107] S5. Prepare building templates

[0108] Mix antioxidant 1076, zinc stearate, tris(2,3-dichloropropyl) phosphate and dipropyl phthalate evenly according to the weight ratio of 1:2:3:2 to obtain the auxiliary additive;

[0109] Weigh by weight: Add 50 parts of aerogel micropowder, 100 parts of polypropylene, 30 parts of crosslinking enhancer and 6 parts of auxiliary additive into a kneader. Raise the temperature of the kneader to 125 °C and knead for 10 min. Add 100 parts of modified fiber and 40 parts of composite flame retardant particles into the kneader in sequence, knead for 25 min. Add 3 parts of benzoyl peroxide into the kneader and knead for 60 min, then granulate to obtain the mixture;

[0110] Spread the mixture on a flat vulcanizer, raise the temperature of the flat vulcanizer to 150 °C, raise the pressure to 16 MPa, keep the temperature and pressure for 60 min, and discharge after cooling to room temperature to obtain the building template.

[0111] Comparative Example 1

[0112] The difference between this comparative example and Example 3 is that in step S1, 1,3,5-cyclohexanetriol is used to replace triphenylthiophenetriazine in an equimolar amount to participate in the preparation of the crosslinking enhancer.

[0113] Comparative Example 2

[0114] The difference between this comparative example and Example 3 is that in step S2, aluminum sec-butoxide is not added.

[0115] Comparative Example 3

[0116] The difference between this comparative example and Example 3 is that step S3 is cancelled, and the fiber powder in step S3 is used to replace the modified fiber in step S5.

[0117] Comparative Example 4

[0118] The difference between this comparative example and Example 3 is that in step S4, the modifier solution is not added.

[0119] Performance test:

[0120] The mechanical properties, flame retardant properties, and heat insulation and heat preservation properties of the building templates prepared in Examples 1-3 and Comparative Examples 1-4 were tested. Among them, for the mechanical properties, with reference to the standard GB / T 29500-2013 "Wood-plastic composite boards for building templates", the static bending strength, simply supported beam impact strength, alkali resistance, and water absorption rate of the specimens were measured; for the flame retardant properties, with reference to the standard GB 8624-2012 "Classification of combustion performance of building materials and products", the combustion performance grade of the specimens was measured; for the heat insulation and heat preservation properties, with reference to the standard GB / T 32064-2015 "Transient plane heat source method for testing thermal conductivity and thermal diffusivity of building materials", the thermal conductivity of the specimens was measured. The specific test results are shown in Tables 1-2:

[0121] Table 1 - Data sheet for mechanical property detection of specimens

[0122] Group Item Flexural Strength / MPa <![CDATA[Izod impact strength / kJ·m -2 > Water Absorption Rate / % Alkali Resistance Example 1 51.3 17.5 0.231 No Bubbling or Cracking on the Surface Example 2 52.1 17.8 0.214 No Bubbling or Cracking on the Surface Example 3 51.8 17.4 0.223 No Bubbling or Cracking on the Surface Comparative Example 1 50.3 17.1 0.228 No Bubbling or Cracking on the Surface Comparative Example 2 50.7 17.3 0.225 No Bubbling or Cracking on the Surface Comparative Example 3 43.6 15.2 0.487 Slight Bubbling and Cracking on the Surface Comparative Example 4 49.6 16.7 0.311 Slight Bubbling and No Cracking on the Surface

[0123] Table 2 - Data sheet for flame retardant and heat insulation and heat preservation property detection of specimens

[0124] Group Item Combustion Performance Grade / level <![CDATA[Thermal conductivity / W·(m·K) -1 > Example 1 A2 0.15 Example 2 A2 0.12 Example 3 A2 0.14 Comparative Example 1 B 0.17 Comparative Example 2 B 0.21 Comparative Example 3 A2 0.35 Comparative Example 4 A2 0.17

[0125] Data analysis:

[0126] Comparative analysis was carried out on the data in Tables 1-2 above. In the building template material prepared in the present invention, the static bending strength reached 52.1 MPa, the simply supported beam impact strength reached 17.8 kJ / m 2 , the water absorption rate was reduced to 0.214%, the combustion performance grade reached A2 level, the thermal conductivity was reduced to 0.12 W / (m·K), and the building template had good alkali resistance. All performance parameters were superior to those of the comparative examples;

[0127] It shows that the present invention reuses rice husks and rice straw as reinforcing fibers, which helps to reduce environmental pollution and resource waste, conforms to the concept of green building and sustainable development, uses aerogel micropowder and composite flame retardant particles as reinforcing materials to reinforce the modified fibers, and uses polypropylene and crosslinking enhancer as organic binders. Under the action of the initiator, it promotes the establishment of crosslinked bonds of molecular bonds between the molecules of the building template. While improving the overall mechanical properties of the building template, it further improves the heat insulation and heat preservation properties, flame retardant properties, and water and alkali resistance of the building template material.

[0128] The above content is only an example and description of the structure of the present invention. Those skilled in the art of this technology make various modifications or supplements to the described specific embodiments or use similar methods for substitution. As long as they do not deviate from the structure of the invention or exceed the scope defined by this claim book, they should fall within the protection scope of the present invention.

[0129] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

[0130] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not elaborate all the details, nor do they limit the invention to only the specific implementation manners. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A fiber-reinforced composite environmentally friendly building formwork, characterized in that, It comprises the following components by weight parts: 80 - 100 parts of polypropylene, 20 - 30 parts of crosslinking enhancer, 30 - 50 parts of aerogel micropowder, 80 - 100 parts of modified fiber, 30 - 40 parts of composite flame retardant particles, 2 - 3 parts of initiator and 4 - 6 parts of auxiliary additive; The crosslinking enhancer is obtained by the following steps: A1. Add 4 - aminothiophenol, absolute ethanol and formaldehyde solution into a reaction kettle and stir. Raise the temperature of the reaction kettle to 60 - 70 °C, keep the temperature for reaction for 6 - 8 h, and perform post - treatment to obtain triphenylthiol triazine; A2. Add triphenylthiol triazine, isophorone diisocyanate and toluene into a reaction kettle protected by nitrogen and stir. Raise the temperature of the reaction kettle to 50 - 60 °C, add a catalyst into the reaction kettle, keep the temperature for reaction for 3 - 4 h, add 5 - methyl - 2 - (1 - methylethenyl) - 4 - hexen - 1 - ol into the reaction kettle, keep the temperature for reaction for 4 - 5 h, and perform post - treatment to obtain the crosslinking enhancer; The modified fiber is obtained by the following steps: B1. Add rice husk and rice straw into a pulverizer and pulverize them into fiber powder with a particle size of 5 - 8 mm; B2. Add the fiber powder and activation liquid into a reaction kettle and stir. Raise the temperature of the reaction kettle to 70 - 80 °C, keep the temperature for reaction for 2 - 3 h, and perform post - treatment to obtain pretreated fiber. Among them, the activation liquid consists of potassium hydroxide, urea, sodium dodecyl sulfate, 10 wt% hydrogen peroxide and purified water according to the dosage ratio of 5 g:2 g:1 g:30 g:60 mL; B3. Add the pretreated fiber, absolute ethanol and KH - 570 into a reaction kettle and stir for 20 - 30 min. Add 5 wt% sodium hydroxide solution into the reaction kettle, raise the temperature of the reaction kettle to 50 - 60 °C, keep the temperature for treatment for 3 - 4 h, and perform post - treatment to obtain the modified fiber.

2. The fiber-reinforced composite environmentally friendly building formwork according to claim 1, characterized in that, The initiator is benzoyl peroxide. The auxiliary additive consists of antioxidant, dispersant, flame retardant and plasticizer according to the weight ratio of 1:2:3:

2. The antioxidant is one or more of antioxidant 168, antioxidant 1010 and antioxidant 1076. The dispersant is one or more of sodium stearate, calcium stearate, zinc stearate and magnesium stearate. The flame retardant is one or more of tributyl phosphate, tris(2 - ethylhexyl) phosphate, tris(2 - chloroethyl) phosphate, tris(2,3 - dichloropropyl) phosphate and tris(2,3 - dibromopropyl) phosphate. The plasticizer is phthalate.

3. The fiber-reinforced composite environmentally friendly building formwork according to claim 1, characterized in that, In step A1, the dosage ratio of 4 - aminothiophenol, absolute ethanol and formaldehyde solution is 1 g:6 mL:3 - 5 g, and the mass fraction of the formaldehyde solution is 30 - 37%. In step A2, the molar ratio of triphenylthiol triazine, isophorone diisocyanate and 5 - methyl - 2 - (1 - methylethenyl) - 4 - hexen - 1 - ol is 1:3:

3. The dosage ratio of isophorone diisocyanate, toluene and catalyst is 1 g:5 mL: 0.01 g, and the catalyst is dibutyltin diacetate.

4. A fiber-reinforced composite environmentally friendly building formwork according to claim 1, characterized in that, The preparation method of the aerogel micropowder is as follows: Add aluminum sec-butoxide and isopropanol into a reaction kettle and stir until the system is dissolved. Raise the temperature of the reaction kettle to 70 - 80 °C, add dilute nitric acid into the reaction kettle, keep the temperature for reaction for 2 - 3 h, add tetraethyl orthosilicate and allyltriethoxysilane into the reaction kettle, keep the temperature and stir for 2 - 3 h, stand for aging for 8 - 10 h, and perform post-treatment to obtain the aerogel micropowder.

5. A fiber-reinforced composite environmentally friendly building formwork according to claim 4, characterized in that, The dosage ratio of aluminum sec-butoxide, isopropanol, dilute nitric acid, tetraethyl orthosilicate and allyltriethoxysilane is 3 - 5 g: 30 - 50 mL: 5 - 7 mL: 8 - 10 g: 2 - 3 g, and the concentration of the dilute nitric acid is 0.8 - 1.3 mol / L.

6. The fiber-reinforced composite environmentally friendly building formwork according to claim 1, wherein In step B2, the dosage ratio of the fiber powder to the activation liquid is 1 g: 10 - 15 mL; in step B3, the dosage ratio of the pretreated fiber, absolute ethanol, KH-570 and 5 wt% sodium hydroxide solution is 5 g: 50 mL: 2 - 3 g: 10 mL.

7. The fiber-reinforced composite environmentally friendly building formwork according to claim 1, wherein, The composite flame retardant particles are processed by the following steps: C1. Place diatomite in a muffle furnace, raise the temperature of the muffle furnace to 450 - 500 °C, keep the temperature for treatment for 3 - 4 h, and naturally cool down to room temperature to obtain the calcined powder; C2. Add the calcined powder and phosphoric acid solution into a reaction kettle and stir. Raise the temperature of the reaction kettle to 70 - 80 °C, keep the temperature and stir for 30 - 40 min. Add urea solution into the reaction kettle, raise the temperature of the reaction kettle to the reflux of the system, keep the temperature for reaction for 60 - 80 min. Add the modification liquid into the reaction kettle, and perform post-treatment to obtain the crude composite flame retardant particles; C3. Transfer the crude composite flame retardant particles to a ball mill, set the rotation speed of the ball mill to 200 - 250 r / min, and ball mill for 30 - 40 min to obtain the composite flame retardant particles.

8. A fiber-reinforced composite environmentally friendly building formwork according to claim 7, characterized in that, In step C2, the dosage ratio of the calcined powder, phosphoric acid solution, urea solution and modification liquid is 10 g: 20 mL: 10 mL: 5 g, the concentration of the phosphoric acid solution is 1.5 mol / L, the concentration of the urea is 3.2 mol / L, and the modification liquid is composed of trifluorooctyltrimethoxysilane and allyltriethoxysilane according to the weight ratio of 2:

1.

9. The preparation method of a fiber-reinforced composite environmentally friendly building formwork according to any one of claims 1-8, characterized in that, It includes the following steps: S1. Add the aerogel micropowder, polypropylene, crosslinking enhancer and auxiliary additive into a kneader, raise the temperature of the kneader to 115 - 125 °C, knead for 5 - 10 min, sequentially add the modified fiber and composite flame retardant particles into the kneader, knead for 15 - 25 min, add an initiator into the kneader, knead for 40 - 60 min, and granulate to obtain the mixture; S2. Spread the mixture on a flat vulcanizer, raise the temperature of the flat vulcanizer to 140 - 150 °C, raise the pressure to 12 - 16 MPa, keep the temperature and pressure for treatment for 40 - 60 min, naturally cool down to room temperature and then discharge to obtain the building formwork.

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