High-temperature-resistant plant fiber-based fireproof and heat-insulating plate and preparation method thereof

Abstract

The application discloses a high-temperature-resistant plant fiber-based fireproof and heat-insulating plate and a preparation method thereof, and belongs to the technical field of fireproof building materials, and aims to solve the technical problem that the fireproof and heat-insulating performances of the plant fiber-based plate in the prior art need to be further improved. The application is prepared by using boron-silicon hybrid phosphazene vitrification gel, titanium phytate hybrid cementation gel and light composite mineral heat-insulating filler as key components, wherein the boron-silicon hybrid phosphazene vitrification gel provides vitrification fire-retardant and high-temperature barrier effects, the titanium phytate hybrid cementation gel enhances the interface cementation and structure integration among the multiphase components, and the light composite mineral heat-insulating filler constructs a porous and multi-interface heat resistance path, so that the plate has the effects of fire-retardant and smoke-suppression, heat-insulation and heat-resistance and structure stability and maintenance.

Description

Technical Field

[0001] This invention relates to the field of fire-resistant building materials technology, specifically to a high-temperature resistant plant fiber-based fireproof and heat-insulating board and its preparation method. Background Technology

[0002] Fireproof and heat-insulating boards are mostly made of inorganic cementitious materials, plant fibers, mineral fillers, flame retardants, and lightweight heat-insulating components. Common types include silicate boards, gypsum boards, magnesium cementitious boards, and fiber-reinforced composite heat-insulating boards. These products are usually formed by combining fibers and fillers through a cementing phase, and utilize the fire resistance of mineral components, the low thermal conductivity of lightweight fillers, and the flame-suppressing effect of flame retardant additives to meet the fireproof and heat-insulating requirements in applications such as building envelope, equipment covering, and protective partitions.

[0003] Currently, some fireproof and heat-insulating boards rely primarily on a single type of flame retardant or ordinary inorganic filler to achieve their flame-retardant, smoke-suppressing, and heat-insulating effects under heat or flame. The surface residual structure formed by the system at high temperatures lacks continuity and density, making it prone to loose char layers, cracking of inorganic layers, or localized detachment. This results in heat and oxygen continuing to transfer into the board, and limited smoke release control capabilities, making it difficult to simultaneously achieve both fire resistance retention and heat insulation stability under continuous heating conditions.

[0004] In addition, there are often problems such as insufficient interfacial compatibility, dispersed bonding points, and low degree of internal integration among plant fibers, organic binders, and mineral fillers. Especially when the amount of filler added is high or there are many types of components, local agglomeration, loose structure, uneven stress transmission, and insufficient cohesion after molding are more likely to occur. These problems not only affect the overall structural stability of the board under normal conditions, but also amplify the tendency of debonding and instability between multiphase components during heating, thereby weakening the comprehensive protective effect of the board.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a high-temperature resistant plant fiber-based fireproof and heat-insulating board and its preparation method, which solves the technical problem that the fire resistance and heat insulation performance of plant fiber-based boards in the prior art need to be further improved.

[0007] The objective of this invention can be achieved through the following technical solution: a method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board, comprising the following steps:

[0008] S1. Add deionized water and anhydrous ethanol to the dispersion tank and stir. After mixing evenly, add glacial acetic acid to adjust the pH of the reaction system to 4.5-4.8. Then add short-cut softwood pulp fibers for dispersion. After even dispersion, add borosilicate hybrid phosphazene ceramic gel, phytate titanium hybrid cementing gel and lightweight composite mineral thermal insulation filler and continue stirring until evenly mixed. After filtration and molding, control the moisture content of the wet felt to 55-60 wt% to obtain the reaction-assembled fiber wet felt.

[0009] S2. Place the reactive assembled fiber wet felt in a hot press and hot press it at 145-160℃ and 4-6MPa for 10-14 minutes. Then raise the temperature to 165-175℃ and hold for 12-18 minutes. After hot pressing, cool it down to below 60℃ to demold, trim the edges, and let it stand at 23-27℃ for 20-28 hours to obtain a fireproof and heat-insulating board.

[0010] Furthermore, in step S1, the ratio of deionized water, anhydrous ethanol, chopped softwood pulp fibers, borosilicate hybrid phosphazene ceramic gel, phytate titanium hybrid cementing gel, and lightweight composite mineral thermal insulation filler is 180mL:15-21mL:24-28g:6-8g:12-18g:10-12g.

[0011] Furthermore, the lightweight composite mineral thermal insulation filler is obtained by mixing expanded perlite, vermiculite, magnesium hydroxide and sepiolite in a ratio of 9-11g:5-6g:5-6g:3-4g and then grinding them through a 100-mesh sieve.

[0012] Furthermore, the preparation method of the borosilicate hybrid phosphazene ceramic gel is as follows: aryl-modified phosphazene resin, 3-(methacryloyloxy)propyltrimethoxysilane, anhydrous ethanol, deionized water, boric acid, and azobisisobutyronitrile are added to a reaction vessel and stirred. After mixing evenly, the reaction vessel is heated to 70-80℃ and stirred for 3-4 hours. Then, 25wt% ammonia water is added to adjust the pH to 8.6-8.9, and the mixture is aged at 35-45℃ for 2-4 hours. After the reaction is completed, the filter cake is collected by suction filtration, washed, and dried to obtain the borosilicate hybrid phosphazene ceramic gel.

[0013] Furthermore, in the preparation of borosilicate hybrid phosphazene ceramic gel, the ratio of the aryl-modified phosphazene resin, 3-(methacryloyloxy)propyltrimethoxysilane, anhydrous ethanol, deionized water, boric acid, and azobisisobutyronitrile is 50g:15-18mL:360mL:50mL:6-9g:0.6-0.9g.

[0014] Furthermore, the aryl-modified phosphazene resin is prepared by the following method:

[0015] A1. Add hexachlorocyclotriphosphazene to a reactor, heat to 245-255℃ under nitrogen protection, keep warm and stir for 4-6 hours, cool down and discharge after the reaction is complete, then crush and pass through an 80-mesh sieve to obtain chlorophosphazene-based precursor;

[0016] A2. Add chlorophosphazene precursor, eugenol, potassium carbonate and acetonitrile to a reaction vessel and stir. After mixing evenly, heat to 65-75℃ under nitrogen protection and stir for 8-10 hours. After the reaction is completed, wait for the reaction system to cool to room temperature, filter, collect the filter cake and wash and dry it to obtain aryl-modified phosphazene resin.

[0017] Furthermore, in step A2, the ratio of the chlorophosphazene substrate precursor, eugenol, potassium carbonate, and acetonitrile is 40-50g:75mL:50-60g:500mL.

[0018] Furthermore, the phytate-titanium hybrid cemented gel is prepared by the following method:

[0019] B1. Add diethylenetriamine, anhydrous ethanol and deionized water to the reactor and stir. After mixing evenly, add N,N'-methylenebisacrylamide in ten batches with an interval of 5 min between additions. Then heat the reactor to 55°C and keep it at that temperature for 4-6 h with stirring. Post-processing yields the amine polymerization intermediate.

[0020] B2. Add the amine polymerization intermediate, 50wt% phytic acid aqueous solution and deionized water to the reaction vessel and stir. After mixing evenly, add 15wt% titanium oxysulfate aqueous solution and then add 25wt% ammonia to adjust the pH of the reaction system to 3.8-4.3. Then heat the reaction vessel to 30-40℃ and stir for 2-3 hours. After the reaction is completed, reduce the pressure and concentrate to a solid content of 35-40wt% to obtain titanium phytate hybrid cemented gel.

[0021] Further, in step B1, the ratio of diethylenetriamine, anhydrous ethanol, deionized water and N,N'-methylenebisacrylamide is 5-6 mL:30 mL:30 mL:8-9 g, and the post-treatment includes: after the reaction is completed, the mixture is concentrated under reduced pressure to a solid content of 40-45 wt% to obtain an amino polymerization intermediate.

[0022] Furthermore, in step B2, the ratio of the amount of the amine polymerization intermediate, 50wt% phytic acid aqueous solution, deionized water and 15wt% titanium oxysulfate aqueous solution is 7-9g:2-3mL:15-20mL:3-4mL.

[0023] The present invention also discloses a high-temperature resistant plant fiber-based fireproof and heat-insulating board, which is prepared by the above-mentioned preparation method of a high-temperature resistant plant fiber-based fireproof and heat-insulating board.

[0024] The present invention has the following beneficial effects:

[0025] 1. The borosilicate hybrid phosphazene ceramic gel prepared by this invention is embedded between the plant fiber skeleton and mineral fillers as a continuously distributed heat-resistant phase. After hot pressing, it forms an organic-inorganic composite network together with the phytate titanium hybrid cemented gel. When the material is in a fire environment, the phosphazene component, borosilicate component, and phytate titanium coordination structure do not respond independently, but gradually form a relatively continuous and dense residual phase in the surface and near-surface areas of the plate, which constrains heat input, the escape of combustible volatiles, and the further entry of oxygen into the plate. At the same time, the lightweight composite mineral filler plays a supporting and stabilizing role for the high-temperature residual structure, which delays the instability trend of the fiber skeleton during heating. Due to this structural configuration and its synergistic effect during heating, the plate exhibits more favorable fire resistance response characteristics in terms of combustion performance level, average temperature rise in the furnace, and smoke density level.

[0026] 2. The lightweight composite mineral insulating filler prepared by this invention does not exist in a single filling state inside the board, but is dispersed and embedded in the spatial skeleton formed by plant fibers, and is fixed in the continuous phase by borosilicate hybrid phosphazene ceramic gel and phytate titanium hybrid cementing gel. The resulting multiphase composite structure contains fiber interwoven units, lightweight mineral units and gel connecting units inside the board. When heat is transferred in the thickness direction, it needs to pass through different interfaces and different heat transfer paths in sequence, and the continuous direct heat transfer is weakened. Furthermore, during the heating process, the two types of hybrid gels have a maintaining effect on the bonding state of the filler and fiber interface, reducing the reconstruction of heat transfer channels caused by local loosening, migration or collapse. This allows the board to maintain a relatively stable internal insulation pattern under normal and thermal conditions. Correspondingly, the heat transfer level reflected by the thermal conductivity matches the structure configuration, and the insulation performance of the board is reflected in the overall structure.

[0027] 3. The phytate-titanium hybrid cemented gel prepared in this invention mainly participates in the continuous connection between the fiber skeleton and the inorganic phase in this system. During the hot pressing process, it promotes the formation of a relatively stable interface transition region between plant fibers, mineral fillers, and borosilicate hybrid phosphazene ceramic gel. Unlike the plates that rely solely on fiber stacking or inorganic filler compaction, the introduction of this cementing phase gradually transforms the internal contact of the plate from point-like contact to a planar and network-like synergistic combination. The stress transmission path during the compression process is more continuous, and local stress concentration and interface delamination are correspondingly suppressed. At the same time, the borosilicate hybrid phosphazene ceramic gel maintains the structural integrity after molding, and the mineral filler fills and supports the skeleton voids, so that the plate maintains a relatively balanced internal load-bearing pattern under load. Based on this type of structural organization, the mechanical characterization corresponding to the compressive strength has a relatively consistent correspondence with the overall density of the plate, the interface bonding state, and the structural retention ability after heating. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a SEM image of the borosilicate hybrid phosphazene ceramic gel prepared in Example 3 of the present invention;

[0030] Figure 2 This is a SEM image of the phytate-titanium hybrid cemented gel prepared in Example 6 of the present invention. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0032] In this application, the short-cut fibers of softwood pulp used have a length of 3.0 mm, a fiber diameter of 30 μm, and a moisture content of ≤8%.

[0033] Example 1

[0034] This embodiment provides a method for preparing borosilicate hybrid phosphazene ceramic gel, including the following steps:

[0035] Step I: Preparation of chlorophosphazene substrate precursor

[0036] Weigh 60.0g of hexachlorocyclotriphosphazene and add it to the reactor. Under nitrogen protection, heat the mixture to 245℃ and stir for 4 hours. After the reaction is complete, cool the mixture and discharge it. Then crush the mixture through an 80-mesh sieve to obtain the chlorophosphazene-based precursor.

[0037] Step II: Preparation of aryl-modified phosphazene resin

[0038] Weigh out 40.0g of chlorophosphazene precursor, 75.0mL of eugenol, 50.0g of potassium carbonate and 500.0mL of acetonitrile and add them to the reaction vessel. Stir and mix evenly. Then heat to 65℃ under nitrogen protection and keep stirring for 8h. After the reaction is completed, wait for the reaction system to cool to room temperature, filter, collect the filter cake and wash and dry it to obtain aryl-modified phosphazene resin.

[0039] Step III: Preparation of borosilicate hybrid phosphazene ceramic gel

[0040] Weigh out 50.0g of aryl-modified phosphazene resin, 15.0mL of 3-(methacryloyloxy)propyltrimethoxysilane, 360.0mL of anhydrous ethanol, 50.0mL of deionized water, 6.0g of boric acid, and 0.6g of azobisisobutyronitrile and add them to the reaction vessel. Stir and mix thoroughly. Then heat the reaction vessel to 70℃ and keep it at this temperature for 3h. Then add 25wt% ammonia water to adjust the pH to 8.6 and age it at 35℃ for 2h. After the reaction is complete, filter and collect the filter cake. After washing and drying, borosilicate hybrid phosphazene ceramic gel is obtained.

[0041] The reaction principle for preparing borosilicate hybrid phosphazene ceramic gel is as follows:

[0042] Hexachlorocyclotriphosphazene undergoes ring-opening polymerization at high temperatures to form an intermediate phosphazene structure with phosphorus-nitrogen bonds as the main chain and active chlorinated phosphorus groups retained on the side groups. Subsequently, eugenol is converted into phenolate by potassium carbonate, which substitutes the active chlorinated groups on the phosphorus atoms, causing some side groups to be converted into aryloxy-substituted structures. Further, 3-(methacryloyloxy)propyltrimethoxysilane undergoes hydrolysis and condensation in an alcohol-water system to form a network structure containing silicon-oxygen bonds. Boric acid participates in the condensation and complexation in this system, thereby forming a hybrid gel system between the phosphazene organic segments and the silicon-boron inorganic components.

[0043] The working principle of borosilicate hybrid phosphazene ceramic gel in fireproof and heat-insulating boards is as follows:

[0044] The functional structure formed by this process does not ultimately act on the fireproof and heat-insulating board as isolated intermediates, but rather converges into a composite functional phase with borosilicate hybrid phosphazene ceramic gel as the core. This further manifests in the board system as a synergistic construction relationship of "phosphorus-nitrogen flame-retardant skeleton - aromatic carbonization unit - silicon-oxygen inorganic network - boron-containing high-temperature stable unit." Specifically, the chlorophosphazene substrate precursor obtained in step I primarily provides the source of the phosphorus and nitrogen backbone, giving the system the foundation for condensed phase flame retardancy and high-temperature residual phase formation. The aryl-modified phosphazene resin obtained in step II introduces aromatic oxygen structures on this basis, enhancing the organic phase... The carbonization tendency and interfacial compatibility with other components; Step III further couples the above organic structure with silicon-oxygen and boron-oxygen inorganic units to form a hybrid gel with both interfacial distribution capability and thermal ceramicization capability. After this type of structure enters the final board, it is beneficial to improve the internal structure continuity at room temperature, and gradually form a relatively continuous and dense carbon-ceramic composite protective layer during the heating process. It also has a comprehensive impact on heat transfer, oxygen diffusion, smoke release and the stability of the board skeleton, so that the final fireproof and heat-insulating board exhibits a more coordinated performance tendency in terms of flame retardancy, heat insulation and structural maintenance.

[0045] Example 2

[0046] This embodiment provides a method for preparing borosilicate hybrid phosphazene ceramic gel, including the following steps:

[0047] Step I: Preparation of chlorophosphazene substrate precursor

[0048] Weigh 60.0g of hexachlorocyclotriphosphazene and add it to the reactor. Under nitrogen protection, heat the mixture to 255℃ and stir for 6 hours. After the reaction is complete, cool the mixture and discharge it. Then crush the mixture through an 80-mesh sieve to obtain the chlorophosphazene-based precursor.

[0049] Step II: Preparation of aryl-modified phosphazene resin

[0050] Weigh out 50.0g of chlorophosphazene precursor, 75.0mL of eugenol, 60.0g of potassium carbonate and 500.0mL of acetonitrile and add them to the reaction vessel. Stir and mix evenly. Then heat to 75℃ under nitrogen protection and keep stirring for 10h. After the reaction is completed, wait for the reaction system to cool to room temperature, filter, collect the filter cake and wash and dry it to obtain aryl-modified phosphazene resin.

[0051] Step III: Preparation of borosilicate hybrid phosphazene ceramic gel

[0052] Weigh out 50.0g of aryl-modified phosphazene resin, 18.0mL of 3-(methacryloyloxy)propyltrimethoxysilane, 360.0mL of anhydrous ethanol, 50.0mL of deionized water, 9.0g of boric acid, and 0.9g of azobisisobutyronitrile and add them to the reaction vessel. Stir and mix thoroughly. Then heat the reaction vessel to 80℃ and keep it at this temperature for 4h. Then add 25wt% ammonia water to adjust the pH to 8.9 and age it at 45℃ for 4h. After the reaction is completed, filter and collect the filter cake. After washing and drying, borosilicate hybrid phosphazene ceramic gel is obtained.

[0053] Example 3

[0054] This embodiment provides a method for preparing borosilicate hybrid phosphazene ceramic gel, including the following steps:

[0055] Step I: Preparation of chlorophosphazene substrate precursor

[0056] Weigh 60.0g of hexachlorocyclotriphosphazene and add it to the reactor. Under nitrogen protection, heat the mixture to 250℃ and stir for 5 hours. After the reaction is complete, cool the mixture and discharge it. Then crush the mixture through an 80-mesh sieve to obtain the chlorophosphazene-based precursor.

[0057] Step II: Preparation of aryl-modified phosphazene resin

[0058] Weigh out 45.0g of chlorophosphazene precursor, 75.0mL of eugenol, 55.0g of potassium carbonate and 500.0mL of acetonitrile and add them to the reaction vessel. Stir and mix well. Then heat to 70℃ under nitrogen protection and keep stirring for 9h. After the reaction is completed, wait for the reaction system to cool to room temperature, filter, collect the filter cake and wash and dry it to obtain aryl-modified phosphazene resin.

[0059] Step III: Preparation of borosilicate hybrid phosphazene ceramic gel

[0060] Weigh out 50.0 g of aryl-modified phosphazene resin, 16.5 mL of 3-(methacryloyloxy)propyltrimethoxysilane, 360.0 mL of anhydrous ethanol, 50.0 mL of deionized water, 7.5 g of boric acid, and 0.75 g of azobisisobutyronitrile and add them to the reaction vessel. Stir and mix thoroughly. Then heat the reaction vessel to 75 °C and keep it at this temperature for 4 h. Then add 25 wt% ammonia water to adjust the pH to 8.7 and age it at 40 °C for 3 h. After the reaction is complete, filter and collect the filter cake. After washing and drying, borosilicate hybrid phosphazene ceramic gel is obtained.

[0061] Example 4

[0062] This embodiment provides a method for preparing phytate-titanium hybrid cemented gel, including the following steps:

[0063] Step ①: Preparation of amine polymerization intermediate

[0064] Weigh out 50.0 mL of diethylenetriamine, 300.0 mL of anhydrous ethanol and 300.0 mL of deionized water and add them to the reaction vessel. Stir and mix thoroughly. Then add N,N'-methylenebisacrylamide in ten batches, with a total addition amount of 80.0 g and an addition interval of 5 min. Then heat the reaction vessel to 55 °C and keep it at this temperature for 4 h with stirring. After the reaction is completed, concentrate under reduced pressure to a solid content of 40 wt% to obtain the amine polymerization intermediate.

[0065] Step 2: Preparation of phytate-titanium hybrid cemented gel

[0066] Weigh out 70.0 g of amine polymerization intermediate, 20.0 mL of 50 wt% phytic acid aqueous solution and 150.0 mL of deionized water and add them to the reaction vessel. Stir and mix well. Then add 30.0 mL of 15 wt% titanium oxysulfate aqueous solution and 25 wt% ammonia water to adjust the pH of the reaction system to 3.8. Heat the reaction vessel to 30 °C and stir for 2 h. After the reaction is completed, concentrate under reduced pressure to a solid content of 35 wt% to obtain titanium phytate hybrid gel.

[0067] The reaction principle for preparing titanium phytate hybrid cemented gel is as follows:

[0068] The primary and secondary amine groups in the diethylenetriamine molecule undergo nucleophilic addition polymerization with the carbon-carbon double bond of N,N'-methylenebisacrylamide to form a polymerization intermediate with an amide bond in the main chain and retaining some amine sites. Based on this, the polyphosphate groups in the phytic acid molecule can form protonated association and multi-site interactions with this polymeric structure, and at the same time, coordinate with the titanium species provided by titanium oxysulfate. Thus, an organic-inorganic hybrid gel structure characterized by ion association and coordination linkage is established between the organic amine chain segment, the phytic acid phosphate group and the titanium coordination center.

[0069] The working principle of phytate-titanium hybrid cementitious gel in fireproof and heat-insulating panels is as follows:

[0070] The structure obtained by this process does not function as independent intermediates in the final fireproof and heat-insulating board. Instead, they converge into an interfacial cementing functional phase with phytate-titanium hybrid cementing gel as the core. Furthermore, in the board system, this manifests as a composite connection network synergistically constructed by "amine / amide organic segments, polyphosphate associating units, and titanium coordination nodes." Specifically, the amine polymer intermediate obtained in step ① primarily provides an organic framework with a certain degree of flexibility and multi-site interaction capability, laying the foundation for fiber surface wetting, component adhesion, and interfacial transition. Step ②, by introducing phytate and titanium species, forms an organic-inorganic hybrid cementing structure with characteristics of ion association, hydrogen bonding, and coordination linkage. This structure, when incorporated into the final board, enhances the interfacial bonding and spatial integration between plant fibers, borosilicate hybrid phosphazene ceramic gel, and lightweight composite mineral heat-insulating filler, improving the continuity of the board's internal structure and stress transmission state. It also maintains a relatively stable bonding relationship between the multiphase components during heating, thus comprehensively impacting the structural integrity, thermal stability, and overall service performance of the board.

[0071] Example 5

[0072] This embodiment provides a method for preparing phytate-titanium hybrid cemented gel, including the following steps:

[0073] Step ①: Preparation of amine polymerization intermediate

[0074] Weigh out 60.0 mL of diethylenetriamine, 300.0 mL of anhydrous ethanol and 300.0 mL of deionized water and add them to the reaction vessel. Stir and mix thoroughly. Then add N,N'-methylenebisacrylamide in ten batches, with a total addition amount of 90.0 g and an addition interval of 5 min. Then heat the reaction vessel to 55 °C and keep it at this temperature for 6 h with stirring. After the reaction is completed, concentrate under reduced pressure to a solid content of 45 wt% to obtain the amine polymerization intermediate.

[0075] Step 2: Preparation of phytate-titanium hybrid cemented gel

[0076] Weigh out 90.0 g of amine polymerization intermediate, 30.0 mL of 50 wt% phytic acid aqueous solution and 200.0 mL of deionized water and add them to the reaction vessel. Stir and mix well. Then add 40.0 mL of 15 wt% titanium oxysulfate aqueous solution and 25 wt% ammonia water to adjust the pH of the reaction system to 4.3. Heat the reaction vessel to 40 °C and stir for 3 h. After the reaction is completed, concentrate under reduced pressure to a solid content of 40 wt% to obtain titanium phytate hybrid cemented gel.

[0077] Example 6

[0078] This embodiment provides a method for preparing phytate-titanium hybrid cemented gel, including the following steps:

[0079] Step ①: Preparation of amine polymerization intermediate

[0080] Weigh out 55.0 mL of diethylenetriamine, 300.0 mL of anhydrous ethanol and 300.0 mL of deionized water and add them to the reaction vessel. Stir and mix thoroughly. Then add N,N'-methylenebisacrylamide in ten batches, with a total addition amount of 85.0 g and an addition interval of 5 min. Then heat the reaction vessel to 55 °C and keep it at this temperature for 5 h with stirring. After the reaction is completed, concentrate under reduced pressure to a solid content of 43 wt% to obtain the amine polymerization intermediate.

[0081] Step 2: Preparation of phytate-titanium hybrid cemented gel

[0082] Weigh out 80.0g of amine polymerization intermediate, 25.0mL of 50wt% phytic acid aqueous solution and 175.0mL of deionized water and add them to the reaction vessel. Stir and mix well. Then add 35.0mL of 15wt% titanium oxysulfate aqueous solution and 25wt% ammonia water to adjust the pH of the reaction system to 4.05. Heat the reaction vessel to 35℃ and stir for 3h. After the reaction is completed, reduce the pressure and concentrate to a solid content of 38wt% to obtain titanium phytate hybrid gel.

[0083] Example 7

[0084] This embodiment provides a method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board, including the following steps:

[0085] Step 1: Preparation of lightweight composite mineral thermal insulation filler

[0086] Weigh out 9.0g of expanded perlite, 5.0g of vermiculite, 5.0g of magnesium hydroxide and 3.0g of sepiolite, mix them and grind them through a 100-mesh sieve to obtain a lightweight composite mineral thermal insulation filler.

[0087] The working principle of lightweight composite mineral thermal insulation filler in fireproof and heat-insulating boards is as follows:

[0088] The lightweight composite mineral thermal insulation filler obtained by this process does not function as individual mineral particles in the final fireproof and heat-insulating board. Instead, they collectively aggregate into a composite inorganic functional unit that combines lightweight, thermal insulation, support, and high-temperature stability. Furthermore, in the board system, it manifests as a multi-interface thermal insulation system synergistically constructed by "expanded perlite hollow low-density structure - vermiculite layered thermal resistance structure - magnesium hydroxide inorganic thermal resistance unit - sepiolite fibrous support unit". Among them, expanded perlite and vermiculite mainly provide low thermal conductivity, porosity, and layered barrier characteristics. Magnesium hydroxide helps to improve the inorganic stability and thermal buffering capacity of the system during heating. Sepiolite helps to enhance the spatial overlap and structural maintenance between fillers and between fillers and the matrix. After this type of structure enters the final board, it helps to form a porous, multi-interface, long-path thermal transfer barrier network inside, and has a comprehensive impact on the lightweighting, thermal conductivity suppression, high-temperature skeleton support, and overall structural stability of the board. As a result, the final fireproof and heat-insulating board exhibits a more coordinated performance tendency between thermal insulation performance and structural maintenance.

[0089] Step 2: Preparation of reaction-assembled fiber wet mat

[0090] Weigh out 900.0 mL of deionized water and 75.0 mL of anhydrous ethanol and add them to the dispersion tank. Stir and mix evenly. Then add glacial acetic acid to adjust the pH of the reaction system to 4.5. Add 120.0 g of softwood pulp chopped fiber and disperse. After even dispersion, add 30.0 g of borosilicate hybrid phosphazene ceramic gel prepared in Example 1, 60.0 g of phytate titanium hybrid cemented gel prepared in Example 4, and 50.0 g of lightweight composite mineral thermal insulation filler and continue stirring. After even mixing, filter and shape the mixture and control the moisture content of the wet felt to 55 wt% to obtain the reaction-assembled fiber wet felt.

[0091] Step 3: Prepare fireproof and heat-insulating boards

[0092] The reactive assembled fiber wet felt was placed in a hot press and hot-pressed at 145℃ and 4MPa for 10 minutes. Then, the temperature was raised to 165℃ and held for 12 minutes. After hot pressing, the temperature was lowered to below 60℃ to demold, the edges were trimmed, and the board was left to stand at 23℃ for 20 hours to obtain a fireproof and heat-insulating board.

[0093] The reaction principle for preparing fireproof and heat-insulating boards is as follows:

[0094] The surface of short-cut coniferous pulp fibers contains a large number of hydroxyl groups. The borosilicate hybrid phosphazene ceramic gel contains silicon-containing structures that can be further condensed, while the phytate-titanium hybrid cemented gel contains coordination units composed of phosphate groups and titanium species. Therefore, this system mainly involves multiple intermolecular interactions and structural assembly between the fiber skeleton and the two types of hybrid gels. Among them, hydrogen bonds and associations can be formed between the fiber hydroxyl groups and the polar groups in the gel. The silicon-containing components can be further condensed under heating conditions. The phytate phosphate groups maintain coordination relationships with the titanium centers, ultimately forming a plate-like system composed of fiber interweaving, gel interlocking, and multiple combinations.

[0095] Example 8

[0096] This embodiment provides a method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board, including the following steps:

[0097] Step 1: Preparation of lightweight composite mineral thermal insulation filler

[0098] Weigh out 11.0g of expanded perlite, 6.0g of vermiculite, 6.0g of magnesium hydroxide and 4.0g of sepiolite, mix them and grind them through a 100-mesh sieve to obtain a lightweight composite mineral thermal insulation filler.

[0099] Step 2: Preparation of reaction-assembled fiber wet mat

[0100] Weigh out 900.0 mL of deionized water and 105.0 mL of anhydrous ethanol and add them to the dispersion tank. Stir and mix evenly. Then add glacial acetic acid to adjust the pH of the reaction system to 4.8. Add 140.0 g of short-cut softwood pulp fibers and disperse. After even dispersion, add 40.0 g of borosilicate hybrid phosphazene ceramic gel prepared in Example 2, 90.0 g of phytate titanium hybrid cemented gel prepared in Example 5, and 60.0 g of lightweight composite mineral thermal insulation filler and continue stirring. After even mixing, filter and shape the mixture and control the moisture content of the wet felt to 60 wt% to obtain the reaction-assembled fiber wet felt.

[0101] Step 3: Prepare fireproof and heat-insulating boards

[0102] The reactive assembled fiber wet felt was placed in a hot press and hot-pressed at 160℃ and 6MPa for 14 minutes. Then, the temperature was raised to 175℃ and held for 18 minutes. After hot pressing, the temperature was lowered to below 60℃ to demold, the edges were trimmed, and the board was left to stand at 27℃ for 28 hours to obtain a fireproof and heat-insulating board.

[0103] Example 9

[0104] This embodiment provides a method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board, including the following steps:

[0105] Step 1: Preparation of lightweight composite mineral thermal insulation filler

[0106] Weigh out 10.0g of expanded perlite, 5.5g of vermiculite, 5.5g of magnesium hydroxide and 3.5g of sepiolite, mix them and grind them through a 100-mesh sieve to obtain a lightweight composite mineral thermal insulation filler.

[0107] Step 2: Preparation of reaction-assembled fiber wet mat

[0108] Weigh out 900.0 mL of deionized water and 90.0 mL of anhydrous ethanol and add them to the dispersion tank. Stir and mix evenly. Then add glacial acetic acid to adjust the pH of the reaction system to 4.65. Add 130.0 g of softwood pulp chopped fiber and disperse. After even dispersion, add 35.0 g of borosilicate hybrid phosphazene ceramic gel prepared in Example 3, 75.0 g of phytate titanium hybrid cemented gel prepared in Example 6, and 55.0 g of lightweight composite mineral thermal insulation filler and continue stirring. After even mixing, filter and shape the mixture and control the moisture content of the wet felt to 58 wt% to obtain the reaction-assembled fiber wet felt.

[0109] Step 3: Prepare fireproof and heat-insulating boards

[0110] The reactive assembled fiber wet felt was placed in a hot press and hot-pressed at 153℃ and 5MPa for 12 minutes. Then, the temperature was raised to 170℃ and held for 15 minutes. After hot pressing, the temperature was lowered to below 60℃ to demold, the edges were trimmed, and the board was left to stand at 25℃ for 24 hours to obtain a fireproof and heat-insulating board.

[0111] Comparative Example 1

[0112] The difference between this comparative example and Example 9 is that the addition of borosilicate hybrid phosphazene ceramic gel is omitted in step two.

[0113] Comparative Example 2

[0114] The difference between this comparative example and Example 9 is that the addition of titanium phytate hybrid cementing gel is omitted in step two.

[0115] Comparative Example 3

[0116] The difference between this comparative example and Example 9 is that the addition of lightweight composite mineral thermal insulation filler is omitted in step two.

[0117] Performance testing:

[0118] The fire resistance ratings of the fireproof and heat-insulating boards prepared in Examples 7-9 and Comparative Examples 1-3 were tested in accordance with the standard GB 8624-2012 "Classification of Combustion Performance of Building Materials and Products".

[0119] The average furnace temperature rise of the fireproof and heat-insulating boards prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 5464-2010 "Test Method for Non-combustibility of Building Materials".

[0120] The smoke density ratings of the fireproof and heat-insulating boards prepared in Examples 7-9 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 8627-2007 "Test Method for Smoke Density of Building Materials under Combustion or Decomposition".

[0121] The thermal conductivity of the fireproof insulation boards prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 10295-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials - Heat Flow Meter Method".

[0122] The compressive strength of the fireproof and heat-insulating boards prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 5486-2008 "Test Methods for Inorganic Rigid Thermal Insulation Products". The specific data are shown in Table 1.

[0123] Table 1 - Performance Test Data for Each Sample

[0124]

[0125] Data Analysis:

[0126] A comparative analysis of the data in Table 1 reveals that the fireproof and heat-insulating board prepared by this invention has a combustion performance rating of Class A, an average furnace temperature rise of 33°C, a smoke density rating of 8, and a thermal conductivity of 0.046 W·(m·K). -1 Meanwhile, its compressive strength is 0.93 MPa, and all data are superior to the comparative example, indicating that:

[0127] In Comparative Example 1, because borosilicate hybrid phosphazene ceramic gel was not introduced in step two, the original continuous heat-resistant transition structure composed of phosphazene organic phase, borosilicate inorganic phase and fiber skeleton in the plate system could not be established. During heating, the surface area lacked a stable residual phase that could co-evolve with the phytate titanium hybrid cementing gel, which weakened the layer barrier relationship from the surface to the interior of the plate. The structural constraint formed after heat input was discontinuous, and the release path of combustible pyrolysis products was more easily connected. At the same time, the lightweight mineral filler lost the fixing and supporting foundation that cooperated with the ceramic phase under high temperature conditions, and the integrity of the local residual skeleton was difficult to maintain. As a result, the surface protection state, internal structural coordination and subsequent heat shielding of the plate under fire conditions all showed adverse changes.

[0128] In Comparative Example 2, because phytate-titanium hybrid cementing gel was not introduced in step two, there was a lack of effective interfacial cementing medium between the chopped softwood pulp fibers, borosilicate hybrid phosphazene ceramic gel, and lightweight composite mineral thermal insulation filler. The multiphase components inside the board mainly remained in a state of physical contact and mechanical interlocking. During the hot pressing process, it was difficult to form a continuous and uniform bonding transition zone between the components, which weakened the constraint effect of the fiber skeleton on the inorganic filler and ceramic phase, and the stress transmission path inside the board tended to be discrete. Furthermore, under heating or loading conditions, this discontinuous interfacial state was more likely to induce local loosening, microcrack propagation, and structural imbalance, making it difficult to maintain the dense structure and synergistic load-bearing relationship that should have been maintained by the cementing phase. Consequently, the overall integration of the board structure and the structural stability during service were both affected.

[0129] In Comparative Example 3, because lightweight composite mineral insulating filler was not introduced in step two, the porous lightweight barrier unit composed of expanded perlite, vermiculite, magnesium hydroxide, and sepiolite was lost inside the board. Although the composite network formed by the fiber skeleton and the two types of hybrid gels could still exist, the multi-interface heat transfer path in the thickness direction was significantly simplified. During use, heat was more easily transferred along the continuous phase into the board, and the original path extension, interface dissipation, and local support effect formed by the dispersed distribution of mineral particles were difficult to manifest. At the same time, without the mineral filler to fill the space of the fiber-gel network and support the skeleton, the internal pore structure of the board under thermal action was more likely to be reconstructed, and the thermal stress relief capacity of the local area also tended to weaken. As a result, the internal thermal barrier pattern of the board and its maintenance state with temperature change showed a more obvious unfavorable tendency.

[0130] In conclusion, the plate system corresponding to the technical solution of this application is not linearly reinforced around a single flame-retardant phase, a single cementing phase, or a single thermal insulation phase. Instead, in the plant fiber skeleton, through the synergistic introduction of borosilicate hybrid phosphazene ceramic gel, phytate titanium hybrid cementing gel, and lightweight composite mineral thermal insulation filler, the material forms a multiphase coupled interface structure during the molding stage. In the subsequent heating and loading processes, it respectively undertakes the functions of residual phase construction, interface maintenance, path blocking, and skeleton support. When any unit in the comparative example is removed, the continuous transition relationship within the system, the organizational evolution mode under thermal action, and the structural coordination state during service all change accordingly. Based on this material configuration method and its mutual cooperation during operation, it can be shown that the solution of this application is closer to a composite construction system with an overall organizational logic.

[0131] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board, characterized in that, Includes the following steps: S1. Add deionized water and anhydrous ethanol to a dispersion tank and stir. After mixing evenly, add glacial acetic acid to adjust the pH of the reaction system to 4.5-4.

8. Then add short-cut softwood pulp fibers for dispersion. After even dispersion, add borosilicate hybrid phosphazene ceramic gel, phytate titanium hybrid cementing gel and lightweight composite mineral thermal insulation filler and continue stirring. After even mixing, filter and shape the mixture, and control the moisture content of the wet felt to 55-60 wt% to obtain the reaction-assembled fiber wet felt. The ratio of the amount of deionized water, anhydrous ethanol, short-cut softwood pulp fibers, borosilicate hybrid phosphazene ceramic gel, phytate titanium hybrid cementing gel and lightweight composite mineral thermal insulation filler is 180 mL: 15-21 mL: 24-28 g: 6-8 g: 12-18 g: 10-12 g. S2. Place the reactive assembled fiber wet felt in a hot press and hot press it at 145-160℃ and 4-6MPa for 10-14 minutes. Then raise the temperature to 165-175℃ and hold for 12-18 minutes. After hot pressing, cool it down to below 60℃ to demold, trim the edges, and let it stand at 23-27℃ for 20-28 hours to obtain a fireproof and heat-insulating board.

2. The method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board according to claim 1, characterized in that, The lightweight composite mineral thermal insulation filler is obtained by mixing expanded perlite, vermiculite, magnesium hydroxide and sepiolite in a ratio of 9-11g:5-6g:5-6g:3-4g and then grinding them through a 100-mesh sieve.

3. The method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board according to claim 1, characterized in that, The borosilicate hybrid phosphazene ceramic gel is prepared as follows: aryl-modified phosphazene resin, 3-(methacryloyloxy)propyltrimethoxysilane, anhydrous ethanol, deionized water, boric acid, and azobisisobutyronitrile are added to a reaction vessel and stirred. After mixing evenly, the reaction vessel is heated to 70-80℃ and stirred for 3-4 hours. Then, 25wt% ammonia water is added to adjust the pH to 8.6-8.9, and the mixture is aged at 35-45℃ for 2-4 hours. After the reaction is completed, the filter cake is collected by suction filtration, washed, and dried to obtain the borosilicate hybrid phosphazene ceramic gel.

4. The method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board according to claim 3, characterized in that, In the preparation of borosilicate hybrid phosphazene ceramic gel, the ratio of the aryl-modified phosphazene resin, 3-(methacryloyloxy)propyltrimethoxysilane, anhydrous ethanol, deionized water, boric acid, and azobisisobutyronitrile is 50g:15-18mL:360mL:50mL:6-9g:0.6-0.9g.

5. The method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board according to claim 3, characterized in that, The aryl-modified phosphazene resin was prepared by the following method: A1. Add hexachlorocyclotriphosphazene to a reactor, heat to 245-255℃ under nitrogen protection, keep warm and stir for 4-6 hours, cool down and discharge after the reaction is complete, then crush and pass through an 80-mesh sieve to obtain chlorophosphazene-based precursor; A2. Add chlorophosphazene precursor, eugenol, potassium carbonate and acetonitrile to a reaction vessel and stir. After mixing evenly, heat to 65-75℃ under nitrogen protection and stir for 8-10 hours. After the reaction is completed, wait for the reaction system to cool to room temperature, filter, collect the filter cake and wash and dry it to obtain aryl-modified phosphazene resin.

6. The method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board according to claim 5, characterized in that, In step A2, the ratio of the chlorophosphazene substrate precursor, eugenol, potassium carbonate, and acetonitrile is 40-50g:75mL:50-60g:500mL.

7. The method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board according to claim 1, characterized in that, The phytate-titanium hybrid cemented gel was prepared by the following method: B1. Add diethylenetriamine, anhydrous ethanol and deionized water to the reactor and stir. After mixing evenly, add N,N'-methylenebisacrylamide in ten batches with an interval of 5 min between additions. Then heat the reactor to 55°C and keep it at that temperature for 4-6 h with stirring. Post-processing yields the amine polymerization intermediate. B2. Add the amine polymerization intermediate, 50wt% phytic acid aqueous solution and deionized water to the reaction vessel and stir. After mixing evenly, add 15wt% titanium oxysulfate aqueous solution and then add 25wt% ammonia to adjust the pH of the reaction system to 3.8-4.

3. Then heat the reaction vessel to 30-40℃ and stir for 2-3 hours. After the reaction is completed, reduce the pressure and concentrate to a solid content of 35-40wt% to obtain titanium phytate hybrid cemented gel.

8. The method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board according to claim 7, characterized in that, In step B1, the ratio of diethylenetriamine, anhydrous ethanol, deionized water, and N,N'-methylenebisacrylamide is 5-6 mL:30 mL:30 mL:8-9 g; in step B2, the ratio of the amine polymerization intermediate, 50 wt% phytic acid aqueous solution, deionized water, and 15 wt% titanium oxysulfate aqueous solution is 7-9 g:2-3 mL:15-20 mL:3-4 mL.

9. A high-temperature resistant plant fiber-based fireproof and heat-insulating board, characterized in that, The fireproof and heat-insulating board is prepared by the method for preparing a high-temperature resistant plant fiber-based fireproof and heat-insulating board as described in any one of claims 1-8.

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