High-performance biomass flame-retardant composite filler and preparation method thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGDONG DADIZHIYUAN AGRI TECH CO LTD
- Filing Date
- 2026-05-20
- Publication Date
- 2026-06-23
Abstract
Description
Technical Field
[0001] This invention relates to the field of flame-retardant composite materials technology, specifically to a high-performance biomass flame-retardant composite material filler and its preparation method. Background Technology
[0002] With the widespread use of polymer materials in construction, transportation, electronics, and other fields, the fire safety of these materials is receiving increasing attention. Adding flame-retardant fillers is one of the most direct and effective flame-retardant methods. While traditional halogen-based flame-retardant fillers have high flame-retardant efficiency, they release large amounts of toxic and corrosive gases during combustion, seriously threatening personnel safety and polluting the environment. Against the backdrop of increasingly stringent global environmental regulations, halogen-free, low-smoke, and low-toxicity environmentally friendly flame-retardant fillers have become a research hotspot. Currently, inorganic fillers, represented by aluminum magnesium hydroxide, have seen some application, but they generally suffer from excessive addition amounts, often requiring very high filler concentrations to achieve the required flame-retardant rating, leading to severe degradation of the material's mechanical and processing properties. On the other hand, while phosphorus-based, nitrogen-based, and silicon-based organic or inorganic flame-retardant elements each have their own characteristics, their flame-retardant pathways are limited when used alone, making it difficult to simultaneously meet the comprehensive requirements of efficient condensed-phase char formation barrier and gas-phase free radical capture. Therefore, developing novel composite flame-retardant fillers that combine high flame-retardant performance with good matrix compatibility is key to resolving these contradictions.
[0003] In recent years, the use of renewable biomass resources to construct flame-retardant systems has demonstrated unique advantages. Lignosulfonates, a major byproduct of the papermaking industry, contain numerous aromatic rings and hydroxyl groups in their molecular structure, possessing natural char-forming potential. Phytic acid, a cyclic phosphate compound extracted from plant seeds, has an extremely high phosphorus content and can promote matrix dehydration and char formation upon heating, creating a protective carbon layer. Combining these two biomass components yields biomass-based flame-retardant precursors. On the other hand, the rise of nanotechnology has provided new pathways for breakthroughs in the performance of flame-retardant fillers. Boron nitride nanosheets, a graphene-like layered material, possess excellent thermal stability and barrier properties, effectively inhibiting heat and mass transfer. Layered bimetallic hydroxides, namely hydrotalcite, release water vapor and carbon dioxide between layers during combustion, generating a high-specific-surface-area metal oxide layer covering the material surface. However, unmodified boron nitride nanosheets are prone to self-stacking and are difficult to disperse uniformly in water or polymer matrices; ordinary hydrotalcite has limited interlayer active sites, insufficient affinity for polymer chains, and weak synergistic effect in the flame retardant process. To address these issues, researchers have attempted to functionalize these inorganic sheet materials using rare earth element doping and polyoxometalate intercalation. However, effectively combining biomass matrices with various modified inorganic nanostructures and achieving synergistic linkages of components at the molecular scale remains a significant challenge in preparing high-performance biomass flame-retardant fillers. Summary of the Invention
[0004] The purpose of this invention is to provide a high-performance biomass flame-retardant composite filler and its preparation method, which solves the technical problems of existing flame-retardant fillers having large addition amounts, poor compatibility, difficulty in dispersing modified inorganic nanosheets, and difficulty in achieving multi-element synergistic flame retardancy with the biomass matrix.
[0005] The present invention achieves the above objectives through the following technical solutions: A method for preparing a high-performance biomass flame-retardant composite filler, comprising the following steps: S1. By weight, add 10-30 parts of sodium lignosulfonate and 1-8 parts of phytic acid to a three-necked flask containing 400-800 parts of deionized water. Stir at 60-70℃ and adjust the pH to 4.0-5.0 to obtain a biomass dispersion. Disperse 0.5-1.5 parts of γ-aminopropyltriethoxysilane in 100-150 parts of an aqueous ethanol solution, and add 0.5-2 parts of glacial acetic acid dropwise to adjust the pH to 4.0. Hydrolyze 5.0 at 25-40℃; adjust pH to 7.0-8.0, add 2.5-10 parts of cerium-doped zinc borate-modified boron nitride nanosheets and 2.5-10 parts of phosphomolybdic acid-intercalated modified magnesium aluminum lanthanum ternary hydrotalcite, and sonicate to obtain a mixed slurry; add biomass dispersion dropwise to the mixed slurry, stir, adjust temperature to 50-60℃, adjust pH to 5.5-6.5, stir to react, and obtain a reaction mixture; S2. Spray dry the reaction mixture and allow it to cool naturally to room temperature.
[0006] In this invention, the preparation of high-performance biomass flame-retardant composite fillers aims to combine an organic matrix with an inorganic flame retardant through a cross-linking network. Sodium lignosulfonate and phytic acid are dissolved in deionized water under heating and stirring, and the pH is adjusted to form a biomass dispersion. γ-aminopropyltriethoxysilane is dispersed in an ethanol-water solution and hydrolyzed under glacial acetic acid catalysis, converting the terminal ethoxy groups into reactive silanol groups. After adjusting the pH to eliminate electrostatic repulsion, cerium-doped zinc borate-modified boron nitride nanosheets and phosphomolybdic acid-intercalated modified magnesium aluminum lanthanum ternary hydrotalcite are added and ultrasonically treated. During this process, the lamellar hydroxyl and edge hydroxyl groups on the surface of the inorganic carrier undergo dehydration condensation with some silanol groups, causing the silane coupling agent to be partially grafted onto the particle surface. Subsequently, the biomass dispersion is slowly added dropwise to the mixed slurry using a reverse dropwise method, and the temperature and pH are adjusted to trigger the interfacial cross-linking reaction. The grafted amino termini and exposed metal sites coordinate with the sulfonate and phosphate groups of the biomass chain segments through electrostatic attraction and hydrogen bonding, promoting the formation of a three-dimensional cross-linked network of organic-inorganic composites. The reaction mixture is spray-dried, and the water in the droplets evaporates rapidly under a high-temperature gas flow. Under capillary force, the cross-linked network shrinks and solidifies inward, allowing the biomass matrix to encapsulate the inorganic flame retardant within the microspheres. After cooling, a high-performance biomass flame-retardant composite filler is obtained.
[0007] According to a preferred embodiment of the present invention, in step S1, the stirring reaction time is 1.5-3 hours.
[0008] According to a preferred embodiment of the present invention, in step S2, the inlet air temperature of the spray dryer is 150-170°C and the outlet air temperature is 75-85°C.
[0009] According to a preferred embodiment of the present invention, the method for preparing the cerium-doped zinc borate-modified boron nitride nanosheets includes: A1. By weight, mix 3-8 parts of hexagonal boron nitride powder with 90-480 parts of urea, add to a ball mill, and ball mill to obtain a mixture; add the mixture to 200-400 parts of deionized water, centrifuge, wash, and vacuum dry to obtain a dry powder; dissolve 3-5 parts of zinc nitrate hexahydrate, 1.5-2.5 parts of boric acid, 0.15-0.6 parts of cerium nitrate hexahydrate, and 0.1-0.5 parts of trisodium citrate in 80-150 parts of deionized water to obtain a precursor solution; disperse the dry powder in the precursor solution, sonicate, stir, add sodium hydroxide aqueous solution, and adjust the pH to 4.5-5.5 for pre-complexation; add sodium hydroxide aqueous solution, and adjust the pH to 6.8-7.2 to obtain a suspension; transfer the suspension to a reaction vessel and carry out a hydrothermal reaction at 160-180℃ to obtain a reaction mixture; A2. Cool the reaction mixture to room temperature naturally, filter it to obtain a precipitate; wash the precipitate alternately with anhydrous ethanol and deionized water, and dry it under vacuum.
[0010] In this invention, the preparation mechanism of the cerium-doped zinc borate-modified boron nitride nanosheets is as follows: Hexagonal boron nitride powder is mixed with urea and undergoes a mechanochemical reaction. Under mechanical shear force, urea molecules wedge into the interlayer of boron nitride, exfoliating it into nanosheets, while simultaneously partially decomposing and introducing active functional groups such as amino and hydroxyl groups at the edge defects of the nanosheets. Subsequently, zinc nitrate hexahydrate, boric acid, cerium nitrate hexahydrate, and trisodium citrate are dissolved in deionized water to form a precursor solution. In the system, trisodium citrate acts as a multidentate chelating bridging agent. When sodium hydroxide aqueous solution is added dropwise to adjust the pH for surface pre-complexation, citrate ions are adsorbed onto the surface of the functionalized nanosheets through hydrogen bonding and electrostatic interactions. Its carboxyl groups coordinate and complex with zinc and cerium ions to construct a ternary complex structure, overcoming the problem of repulsion between free cations and the carrier by the same charge. Alkali solution is added again to adjust the pH to near neutral, and the suspension is transferred to a reaction vessel for hydrothermal reaction. Zinc ions fixed on the surface gradually deprotonate with borate molecules under hydrothermal high temperature, resulting in in-situ crystallization of borate ions. Due to the mismatch between ionic radius and charge, cerium ions mainly exist as interstitial doping and surface modification, causing lattice distortion and generating oxygen vacancies to enhance catalytic carbonization activity, thus promoting the uniform loading of zinc borate crystals on the support surface. After washing and drying, cerium-doped zinc borate-modified boron nitride nanosheets are obtained.
[0011] According to a preferred embodiment of the present invention, in step A1, the hydrothermal reaction is carried out at 160-180°C for 12-18 hours.
[0012] According to a preferred embodiment of the present invention, in step A2, the temperature of vacuum drying is 80-90°C.
[0013] According to a preferred embodiment of the present invention, the preparation method of the phosphomolybdic acid intercalated modified magnesium aluminum lanthanum ternary hydrotalcite includes: B1. By weight, dissolve 0.2-1.5 parts of lanthanum nitrate hexahydrate and 0.3-1.5 parts of trisodium citrate in 20-50 parts of deionized water and stir at 30-40℃ to obtain a lanthanum-citric acid pre-complexed solution; dissolve 15-20 parts of magnesium nitrate hexahydrate and 7-11 parts of aluminum nitrate nonahydrate in 80-150 parts of deionized water to obtain a magnesium-aluminum salt solution; mix the lanthanum-citric acid pre-complexed solution with the magnesium-aluminum salt solution to obtain a mixed metal salt solution; dissolve 5-15 parts of sodium hydroxide in 50-150 parts of deionized water to obtain an alkaline solution; under a nitrogen atmosphere at 55-75℃, add the alkaline solution dropwise to 50-100 parts of deionized water, followed by the mixed metal salt solution, maintaining the pH at 9.8-10.5; after the addition is complete, age the solution at 55-75℃, centrifuge to obtain a precipitate; wash the precipitate with deionized water to obtain a washed precipitate. B2. Dissolve 3-10 parts of phosphomolybdic acid in 80-150 parts of deionized water, add sodium hydroxide aqueous solution dropwise to adjust the pH to 4.0-4.5, and obtain a phosphomolybdic acid buffer solution; disperse the washed precipitate in 50-100 parts of deionized water to obtain a suspension; add the phosphomolybdic acid buffer solution to the suspension, and carry out the intercalation reaction under nitrogen protection at 45-65℃ with stirring, maintaining the pH at 4.0-4.5; add sodium hydroxide aqueous solution dropwise to adjust the pH to 5.5-6.0, and carry out the intercalation stabilization reaction with stirring; after the reaction is completed, centrifuge to obtain the precipitate; wash the precipitate with deionized water at 50-70℃; and vacuum dry.
[0014] In this invention, the synthesis of the phosphomolybdic acid-intercalated modified magnesium-aluminum-lanthanum ternary layered double hydroxide (TLH) is based on the principles of multi-metal co-precipitation and interlayer anion exchange. Since the hydrolysis acid-base threshold of lanthanum ions is significantly lower than that of magnesium and aluminum ions, lanthanum nitrate hexahydrate is first stirred at a constant temperature with trisodium citrate to form a pre-complexed solution. This solution utilizes steric hindrance and coordination to increase its hydrolysis threshold. Then, it is mixed with magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to prepare a metal salt solution. Under nitrogen protection and heating, the metal salt solution and sodium hydroxide alkali solution are added dropwise to deionized water. Under stable alkaline conditions, magnesium, aluminum, and protected lanthanum ions undergo synergistic co-precipitation. Some lanthanum ions enter the magnesia-like layer, while others exist as surface modifications, forming the LDH precursor. Next, phosphomolybdic acid is dissolved and neutralized with alkali solution to obtain a weakly acidic buffer solution. This prevents the layer from dissolving under strong acid and preserves the multi-metal-oxygen cluster cage structure from alkaline degradation. After the precursor is dispersed, it is added to the buffer solution. Large phosphomolybdate anions undergo interlayer anion exchange reactions through electrostatic attraction and diffusion. Subsequently, alkali solution is added dropwise to increase the pH and stabilize the intercalation, allowing the anions to be stably pinned between the layers. After washing and drying, phosphomolybdate-intercalated modified magnesium aluminum lanthanum ternary hydrotalcite is obtained.
[0015] According to a preferred embodiment of the present invention, in step B1, the aging reaction time at 55-75°C is 20-28 hours.
[0016] According to a preferred embodiment of the present invention, in step B2, the temperature of vacuum drying is 60-80°C.
[0017] The present invention also provides a high-performance biomass flame-retardant composite material filler prepared according to the preparation method of the high-performance biomass flame-retardant composite material filler.
[0018] The beneficial effects of this invention are as follows: This invention utilizes sodium lignosulfonate and phytic acid as biomass carbon and acid sources, respectively, and in situ composites them with cerium-doped zinc borate-modified boron nitride nanosheets and phosphomolybdic acid-intercalated modified magnesium aluminum lanthanum ternary layered double hydroxides (TLDs) to construct a multi-element synergistic flame-retardant system. During combustion, sodium lignosulfonate and phytic acid promote the dehydration of the matrix to form char, creating a char precursor. The cerium-doped and zinc borate-modified boron nitride nanosheets, with their excellent thermal stability and barrier properties, catalyze the transformation of the char layer into a dense graphitized structure, forming an expanded protective layer that effectively isolates oxygen and heat feedback. The phosphomolybdic acid-intercalated modified magnesium aluminum lanthanum ternary layered double hydroxides release water vapor and inert components from the decomposition of molybdenum-containing polyacids upon heating, diluting the concentration of combustible gases. The resulting composite metal oxides efficiently capture highly reactive free radicals in the gas-phase combustion chain reaction. The synergistic effect of condensed-phase char formation isolation, gas-phase free radical capture, and gas dilution significantly reduces the heat release rate and smoke density of the material, thus significantly improving flame-retardant efficiency.
[0019] A molecular-level bridge was constructed between the biomass organic phase and the inorganic nano-reinforcing phase through in-situ hydrolysis and condensation of γ-aminopropyltriethoxysilane under controlled acid-base conditions. After hydrolysis, one end of the silane molecule chemically grafts onto the active groups on biomass macromolecules such as sodium lignosulfonate and phytic acid, while the other end coordinates and crosslinks with equi-site hydroxyl groups exposed on the surface of cerium-doped zinc borate-modified boron nitride nanosheets and the interlayer of phosphomolybdic acid-intercalated modified magnesium aluminum lanthanum ternary layered double hydroxide. This process effectively overcomes the defect of easy stacking and aggregation of two-dimensional nanosheets, achieving uniform dispersion and stable anchoring of the inorganic phase in the continuous biomass phase. The resulting composite filler has a unique organic-inorganic hybrid structure, excellent interfacial compatibility with the polymer matrix, and can impart a high flame retardant rating to the material with a low addition amount, while avoiding the mechanical property degradation caused by large-scale filling of traditional fillers, maintaining or even improving the strength and toughness of the material.
[0020] The sodium lignosulfonate in the raw materials is derived from the recycling of byproducts of the papermaking industry, and phytic acid is extracted from natural plant seeds, achieving high-value transformation of industrial waste and effective utilization of renewable resources. The entire synthesis process uses water or ethanol-water solution as the medium, with mild conditions, simple process, and no emission of toxic organic solvents, making it easy for industrial production. The final product is a halogen-free environmentally friendly flame-retardant powder that does not produce corrosive or highly toxic gases during combustion or high-temperature processing, fully meeting the increasingly stringent environmental regulations and safety requirements for flame-retardant materials in the electronics, transportation, and construction industries, and has outstanding environmental benefits and industrial application value. Detailed Implementation
[0021] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.
[0022] Example 1 This embodiment provides a method for preparing high-performance biomass flame-retardant composite filler, the steps of which include: Step S1: Install a constant temperature water bath, mechanical stirrer, and reflux condenser on a three-necked round-bottom flask. Add 600g of deionized water to the flask, turn on the stirrer at 500r / min, add 20g of sodium lignosulfonate and 4.5g of phytic acid, heat the water bath to raise the system temperature to 65℃, and stir at a constant temperature until the sodium lignosulfonate is completely dissolved. Slowly add a 5% sodium hydroxide aqueous solution using a dropping funnel, and adjust the pH of the system to 4.5±0.1 by monitoring with a precision pH meter. Continue stirring for 30min to fully homogenize the system and obtain a biomass dispersion. Keep it at 65℃ for later use. In a separate beaker, 1.0 g of γ-aminopropyltriethoxysilane was added to 125 g of 95% ethanol aqueous solution. A magnetic stir bar was placed in the beaker and stirred to ensure thorough dispersion. 1.25 g of glacial acetic acid was added dropwise while stirring, and the pH of the mixture was monitored with pH paper until it reached 4.5 ± 0.2. The beaker was placed in a constant temperature water bath and the hydrolysis reaction was carried out at 33 °C for 50 min with intermittent stirring. After hydrolysis was completed, 5% sodium hydroxide aqueous solution was slowly added dropwise while stirring to adjust the pH of the system to 7.5 ± 0.1. After stopping the addition, the pH remained stable for 5 min without dropping back. 6.25g of cerium-doped zinc borate-modified boron nitride nanosheets and 6.25g of phosphomolybdic acid-intercalated modified magnesium aluminum lanthanum ternary hydrotalcite were added to the hydrolysate in one go. The beaker was placed in an ultrasonic cleaner and ultrasonically dispersed at 25℃ water bath and 40kHz frequency for 2.5h. During the process, the mixture was stirred with a glass rod every 30min to prevent sedimentation, resulting in a milky gray uniform mixed slurry. The mixed slurry was transferred to a three-necked flask pre-equipped with a mechanical stirrer and a thermometer. The stirrer was turned on at 600 rpm. Using a constant-pressure dropping funnel, all the biomass dispersion, which had been preheated to 65°C, was slowly and evenly added to the mixed slurry over 45 minutes. During the addition, the temperature of the mixed system naturally decreased. After the addition was complete, the water bath was adjusted to control and stabilize the system temperature at 55°C. At 55°C, a 5% sodium hydroxide aqueous solution was slowly added dropwise using a dropping funnel to adjust the pH of the system to 6.0 ± 0.1. After adjustment, the mechanical stirrer speed was increased to 1000 rpm, and the coordination crosslinking reaction was continued at a constant temperature for 2.25 hours, finally yielding a dark gray-brown viscous suspension.
[0023] Step S2: After the reaction is complete, turn off the heating. Take a sample and use a pH meter to check the pH of the suspension. It should be 6.0±0.1, no adjustment is needed. Transfer all the suspension to the feed tank of the spray dryer and turn on the magnetic stirrer to keep the material uniform. The spray drying parameters are set as follows: atomization method is two-fluid spray gun atomization, atomizing compressed air pressure is 0.25MPa; inlet air temperature is set to 160℃, outlet air temperature is set to 80℃; closed-loop nitrogen circulation is used, and the oxygen content in the drying system is monitored by an online oxygen content analyzer to keep it below 2%; the feed rate is adjusted to 30mL / min, and continuous feeding drying begins after all temperature parameters stabilize. After drying, the light brownish-yellow powder product is collected from the bottom of the drying tower and the receiving tank of the cyclone separator, spread on a stainless steel tray, and placed in a dry and clean environment to cool naturally to room temperature. The cooled powder is sieved through a 200-mesh sieve, and the final product is immediately packaged into sealed bottles. Each bottle contains 10g of activated 4A molecular sieve desiccant, the bottle mouth is sealed with sealing film, and stored in a desiccator containing color-changing silica gel to obtain the finished high-performance biomass flame-retardant composite filler.
[0024] Preparation steps of cerium-doped zinc borate-modified boron nitride nanosheets: Step A1: Weigh 5.5g of hexagonal boron nitride powder and 285g of urea, place them in an agate ball mill jar, add agate grinding balls at a ball-to-material mass ratio of 30:1, seal and load into a planetary ball mill, and ball mill at 400r / min for 24h. During ball milling, stop the mill for 15min every 4h to prevent the jar from overheating. After ball milling, transfer the resulting mixture from the jar to a beaker, add 300g of deionized water, centrifuge at 7000r / min for 10min, discard the supernatant, and wash the precipitate repeatedly with 45℃ deionized water three times under the same centrifugation conditions until the pH of the washing liquid is close to neutral. Spread the washed precipitate evenly in a petri dish, place it in a vacuum drying oven, and dry it at 50℃ and -0.095MPa vacuum for 10h. Remove and grind to obtain a dry powder. In a separate beaker, dissolve 4.0g zinc nitrate hexahydrate, 2.0g boric acid, 0.375g cerium nitrate hexahydrate, and 0.3g trisodium citrate in 115g deionized water. Stir magnetically at 30°C until completely dissolved to prepare a clear precursor solution. Add all the dried powders to the precursor solution and ultrasonically disperse using a probe-type ultrasonic cell disruptor under ice-water bath cooling for 2 hours. The ultrasonic power is 300W, and the working mode is intermittent pulse (5s ultrasonic, 3s pause) to obtain a uniform suspension. The suspension was transferred to a three-necked flask, and mechanical stirring was started at 350 rpm. A 5% sodium hydroxide aqueous solution was added dropwise using a constant-pressure dropping funnel, with real-time monitoring via a precision pH meter. The pH of the system was slowly adjusted to 5.0. After adjustment, stirring was continued for 45 minutes for surface pre-complexation. After pre-complexation, a 5% sodium hydroxide aqueous solution was added dropwise until the pH reached 7.0. The system was stirred for 10 minutes until no pH drop occurred, yielding a milky white suspension. This suspension was then transferred entirely to a stainless steel high-pressure reactor with a polytetrafluoroethylene liner, filling it to approximately 75% of its volume. The sealing cap was tightened, and the reactor was placed in a forced-air drying oven. The temperature was increased from room temperature to 170°C at a rate of 5°C / min, and the reaction was carried out at 170°C for 15 hours using a hydrothermal method.
[0025] Step A2: After the hydrothermal reaction is completed, turn off the heating and allow the reactor to cool naturally to room temperature. Open the reactor and transfer all the product inside to a Buchner funnel for vacuum filtration. Wash the filter cake three times each with 75g of anhydrous ethanol and 75g of deionized water, ensuring it is completely dry before proceeding to the next wash. Spread the washed filter cake thinly in a vacuum drying oven and dry it at 85℃ and -0.095MPa vacuum for 24 hours. Lightly grind and disperse the dried blocky product using an agate mortar and pestle. Pass all the powder through a 200-mesh standard sieve. Collect the sieved powder and quickly transfer it to a glass bottle with a sealed cap. Place 20g of activated 4A molecular sieve as a desiccant in the bottle and seal it in a desiccator to obtain cerium-doped zinc borate-modified boron nitride nanosheets.
[0026] Preparation steps of phosphomolybdic acid intercalated modified magnesium aluminum lanthanum ternary hydrotalcite: Step B1: Take 0.85g of lanthanum nitrate hexahydrate and 0.9g of trisodium citrate, add them to a flask containing 35g of deionized water that has been boiled and cooled to remove CO2, and stir at 250r / min in a 35℃ water bath for 20min until dissolved. The solution becomes colorless and transparent, yielding a lanthanum-citric acid pre-complexed solution. Separately, take 17.5g of magnesium nitrate hexahydrate and 9.0g of aluminum nitrate nonahydrate, dissolve them in 115g of deionized water that has also undergone CO2 removal treatment, and stir at room temperature until completely dissolved to obtain a magnesium-aluminum salt solution. Before starting the double drop addition, combine the lanthanum-citric acid pre-complexed solution and the magnesium-aluminum salt solution in a beaker and stir for 5min to mix thoroughly, yielding a mixed metal salt solution. Weigh 10.0g of sodium hydroxide and dissolve it in 100g of deionized water that has been boiled to remove CO2, stir to dissolve, and then cool to room temperature to prepare an alkaline solution. Install a constant temperature water bath jacket, a mechanical stirrer, two constant pressure dropping funnels, a nitrogen inlet tube, and a nitrogen outlet tube on a four-necked round-bottom flask. Add 75g of boiled deionized water (after removing CO2) as the base liquid. Purge the flask with high-purity nitrogen (flow rate 100mL / min) for 30 minutes to remove air from the flask and the liquid surface. Turn on the water bath to stabilize the temperature of the base liquid at 65℃. Under nitrogen protection, add a small amount of alkaline solution dropwise from one dropping funnel to adjust the initial pH of the base liquid to 10. 0±0.1; then simultaneously open both constant-pressure dropping funnels, and add the mixed metal salt solution and the remaining alkali solution dropwise into the stirred bottom liquid using a double-drop method. During the dropwise addition, the pH value of the reaction system is maintained within the range of 10.0±0.2 by adjusting the dropping rate of the alkali solution. The total dropwise addition time is approximately 45 min. After the dropwise addition is completed, switch the nitrogen flow to static protection with sealed tubes, remove the dropping funnels, and quickly seal all interfaces with glass stoppers. Continue to age at 65℃ for 24 h. After aging, turn off the heating, transfer the suspension to a centrifuge tube, centrifuge at 7500 r / min for 10 min, discard the supernatant, and repeatedly centrifuge and wash the precipitate with deionized water. Measure the pH of the supernatant after each centrifugation. Wash until the pH value of the supernatant drops to 7.0±0.2 to obtain the wet hydrotalcite precursor. The wet material is temporarily stored in a sealed beaker to prevent the absorption of CO2 from the air.
[0027] Step B2: Dissolve 6.5g of phosphomolybdic acid in 115g of deionized water. Under magnetic stirring, add 5% sodium hydroxide aqueous solution dropwise using a dropping funnel while monitoring the pH with a pH meter. Adjust the pH of the solution to 4.25±0.05 to obtain a phosphomolybdic acid buffer solution for later use. Transfer all the wet material obtained in step B1 to a three-necked flask, add 75g of deionized water that has been bubbled with high-purity nitrogen to remove CO2, and mechanically stir at 300 rpm to redisperse it into a uniform suspension; continuously purge with nitrogen for protection, and slowly add all the phosphomolybdic acid buffer solution dropwise into the suspension through a constant pressure dropping funnel while stirring, completing the addition in about 30 minutes; raise the water bath to 55°C, maintain this temperature and continuously stir to carry out the first step of the intercalation reaction for 1.5 hours, during which the pH is monitored by an automatic pH monitoring system, and when the pH rises due to the consumption of acid in the reaction, add a small amount of 5% sodium hydroxide aqueous solution dropwise to keep the pH of the system stable at 4.25±0.1; after the first step of the reaction is completed, slowly add 5% sodium hydroxide aqueous solution dropwise to gradually increase the pH of the system to 5.8, and continue stirring at 55°C to carry out the intercalation stabilization reaction for 4 hours, during which the pH is also monitored and maintained at 5.8±0.1. After the reaction was complete, the suspension was transferred to a centrifuge tube while still hot (approximately 55°C) and centrifuged at 8000 r / min for 8 min, discarding the supernatant. The precipitate was repeatedly washed by centrifugation with deionized water preheated to 60°C. After each centrifugation, the pH of the supernatant was measured, and the washing continued until the pH of the supernatant dropped to 7.0 ± 0.2. The washed precipitate was then transferred to a vacuum drying oven and dried at 70°C and -0.095 MPa vacuum for 24 h. After drying, the precipitate was lightly ground in a mortar and pestle, and all of it passed through a 200-mesh standard inspection sieve. The resulting powder was quickly transferred to a sealed glass bottle containing 20 g of activated 4A molecular sieve and stored in a desiccator to obtain phosphomolybdic acid intercalated modified magnesium aluminum lanthanum ternary hydrotalcite.
[0028] Example 2 The specific implementation method is the same as in Example 1, except that this example provides a method for preparing high-performance biomass flame-retardant composite filler, the steps of which include: Step S1: Add 10g of sodium lignosulfonate and 1.0g of phytic acid to a three-necked flask containing 400g of deionized water. Stir mechanically at 400r / min in a 60℃ constant temperature water bath. Add 5% sodium hydroxide aqueous solution dropwise to adjust the pH to 4.0, obtaining a biomass dispersion. Disperse 0.5g of γ-aminopropyltriethoxysilane in 100g of 90% ethanol aqueous solution. Add 0.5g of glacial acetic acid dropwise to adjust the pH to 4.0. Hydrolyze at 25℃ for 40min. Add 5% sodium hydroxide aqueous solution dropwise. Sodium hydroxide aqueous solution was used to adjust the pH to 7.0. 2.5g of cerium-doped zinc borate-modified boron nitride nanosheets and 2.5g of phosphomolybdic acid-intercalated modified magnesium aluminum lanthanum ternary hydrotalcite were added. The mixture was ultrasonically treated for 2h to obtain a mixed slurry. Under stirring, a biomass dispersion at 60℃ was slowly added dropwise to the mixed slurry over 30min. The system temperature was adjusted to 50℃, and a 5% (w / w) sodium hydroxide aqueous solution was added dropwise to adjust the pH to 5.5. The mechanical stirring speed was increased to 800r / min, and the reaction was carried out at a constant temperature for 1.5h to obtain the reaction mixture.
[0029] Step S2: The pH of the reaction mixture is determined to be 5.5, and no adjustment is required; the reaction mixture is transferred to a spray drying device and spray dried and granulated under the conditions of inlet air temperature of 150℃, outlet air temperature of 75℃, closed-loop nitrogen protection and oxygen content <3%; the powder at the bottom of the drying tower is collected, naturally cooled to room temperature, and sealed and stored in a desiccator equipped with 3A molecular sieve to obtain the high-performance biomass flame-retardant composite filler.
[0030] Preparation steps of cerium-doped zinc borate-modified boron nitride nanosheets: Step A1: Weigh 3.0g of hexagonal boron nitride powder and 90g of urea, mix them, add them to a ball mill and ball mill at 300r / min for 20h to obtain a mixture; add the mixture to 200g of deionized water, centrifuge at 6000r / min, wash the precipitate with deionized water, and vacuum dry at 40℃ for 12h to obtain a dry powder. 3.0 g zinc nitrate hexahydrate, 1.5 g boric acid, 0.15 g cerium nitrate hexahydrate, and 0.1 g trisodium citrate were dissolved in 80 g deionized water to prepare a precursor solution. The dried powder was ultrasonically dispersed in the precursor solution and ultrasonically treated for 1 h. A 3% sodium hydroxide aqueous solution was added dropwise with stirring to adjust the pH to 4.5, and stirring was continued for 30 min for pre-complexation. Another 3% sodium hydroxide aqueous solution was added dropwise to adjust the pH to 6.8 to obtain a suspension. The suspension was transferred to a PTFE-lined stainless steel high-pressure reactor with a filling degree of 70%, and hydrothermally reacted at 160 °C for 12 h to obtain the reaction mixture.
[0031] Step A2: Cool the reaction mixture to room temperature naturally, filter it to obtain a precipitate; wash the precipitate three times alternately with 50g of anhydrous ethanol and 50g of deionized water, dry it under vacuum at 80℃ for 20h, pass it through a 200-mesh sieve, and seal it in a desiccator containing 3A molecular sieve to obtain cerium-doped zinc borate modified boron nitride nanosheets.
[0032] Preparation steps of phosphomolybdic acid intercalated modified magnesium aluminum lanthanum ternary hydrotalcite: Step B1: Dissolve 0.2g of lanthanum nitrate hexahydrate and 0.3g of trisodium citrate in 20g of deionized water that has been boiled to remove CO2, and stir at 30°C for 15min to obtain a lanthanum-citric acid pre-complexed solution; dissolve 15.0g of magnesium nitrate hexahydrate and 7.0g of aluminum nitrate nonahydrate in 80g of deionized water that has been boiled to remove CO2 to obtain a magnesium-aluminum salt solution; mix the lanthanum-citric acid pre-complexed solution and the magnesium-aluminum salt solution thoroughly to obtain a mixed metal salt solution; dissolve 5.0g of sodium hydroxide in 50g of deionized water that has been boiled to remove CO2. An alkaline solution was prepared from deionized water that had been boiled to remove CO2. Under a constant temperature water bath at 55°C and nitrogen protection, a small amount of alkaline solution was added dropwise to a reaction flask containing 50g of deionized water that had been boiled to remove CO2, adjusting the initial pH to 9.8. Subsequently, a mixed metal salt solution and the remaining alkaline solution were added dropwise simultaneously and slowly using a double-dropping method to maintain the pH of the reaction system at 9.8±0.2. After the addition was completed, the flask was sealed and aged at 55°C for 20 hours. The precipitate was obtained by centrifugation. The precipitate was washed with deionized water until neutral to obtain the wet material of the hydrotalcite precursor.
[0033] Step B2: Dissolve 3.0 g of phosphomolybdic acid in 80 g of deionized water, add dropwise 6% sodium hydroxide aqueous solution to adjust the pH to 4.0, and obtain a phosphomolybdic acid buffer solution; disperse the wet hydrotalcite precursor in 50 g of deionized water that has been bubbled with nitrogen to remove CO2, and obtain a suspension; under nitrogen protection, slowly add the phosphomolybdic acid buffer solution to the suspension, and continuously stir at 45 °C to carry out the intercalation reaction for 1 h, maintaining the pH at 4.0; then add dropwise 3% sodium hydroxide aqueous solution. The pH of the intercalation stabilization reaction was adjusted to 5.5 using a % sodium hydroxide aqueous solution and stirred for 2 hours. After the reaction was completed, the precipitate was separated by centrifugation at 7000 r / min while hot. The precipitate was washed repeatedly with deionized water at 50℃ until the pH of the supernatant dropped to 6.5. The washed precipitate was vacuum dried at 60℃ for 12 hours, passed through a 200-mesh sieve, and sealed and stored in a desiccator containing 3A molecular sieve to obtain phosphomolybdic acid intercalated modified magnesium aluminum lanthanum ternary hydrotalcite.
[0034] Example 3 The specific implementation method is the same as in Example 1, except that this example provides a method for preparing high-performance biomass flame-retardant composite filler, the steps of which include: Step S1: Add 30g of sodium lignosulfonate and 8.0g of phytic acid to a three-necked flask containing 800g of deionized water. Stir mechanically at 600r / min in a 70℃ constant temperature water bath. Add 10% sodium hydroxide aqueous solution dropwise to adjust the pH to 5.0, obtaining a biomass dispersion. Disperse 1.5g of γ-aminopropyltriethoxysilane in 150g of 95% ethanol aqueous solution. Add 2.0g of glacial acetic acid dropwise to adjust the pH to 5.0. Hydrolyze at 40℃ for 60min. Add 10% sodium hydroxide aqueous solution dropwise. A sodium hydroxide aqueous solution was prepared, and the pH was adjusted to 8.0. 10.0 g of cerium-doped zinc borate-modified boron nitride nanosheets and 10.0 g of phosphomolybdic acid-intercalated modified magnesium aluminum lanthanum ternary hydrotalcite were added. The mixture was ultrasonically treated for 3 h to obtain a mixed slurry. Under stirring, a biomass dispersion at 70 °C was slowly added dropwise to the mixed slurry over 60 min. The system temperature was adjusted to 60 °C, and a 10% (w / w) sodium hydroxide aqueous solution was added dropwise to adjust the pH to 6.5. The mechanical stirring speed was increased to 1200 r / min, and the reaction was carried out at a constant temperature for 3.0 h to obtain the reaction mixture.
[0035] Step S2: The pH of the reaction mixture is determined to be 6.5, and no adjustment is required; the reaction mixture is transferred to a spray drying device and spray dried and granulated under the conditions of inlet air temperature of 170℃, outlet air temperature of 85℃, closed-loop nitrogen protection and oxygen content <3%; the powder at the bottom of the drying tower is collected, naturally cooled to room temperature, and sealed and stored in a desiccator equipped with 4A molecular sieve to obtain high-performance biomass flame-retardant composite filler.
[0036] Preparation steps of cerium-doped zinc borate-modified boron nitride nanosheets: Step A1: Weigh 8.0g of hexagonal boron nitride powder and 480g of urea, mix them, add them to a ball mill and ball mill at 500r / min for 30h to obtain a mixture; add the mixture to 400g of deionized water, centrifuge at 8000r / min, wash the precipitate with deionized water, and vacuum dry at 60℃ for 8h to obtain a dry powder. 5.0 g of zinc nitrate hexahydrate, 2.5 g of boric acid, 0.6 g of cerium nitrate hexahydrate, and 0.5 g of trisodium citrate were dissolved in 150 g of deionized water to prepare a precursor solution. The dried powder was ultrasonically dispersed in the precursor solution and ultrasonically treated for 3 h. A 5% sodium hydroxide aqueous solution was added dropwise with stirring to adjust the pH to 5.5, and stirring was continued for 60 min for pre-complexation. Another 5% sodium hydroxide aqueous solution was added dropwise to adjust the pH to 7.2 to obtain a suspension. The suspension was transferred to a stainless steel high-pressure reactor lined with polytetrafluoroethylene, with a filling degree of 80%, and hydrothermally reacted at 180 °C for 18 h to obtain the reaction mixture.
[0037] Step A2: Cool the reaction mixture naturally to room temperature, filter it to obtain a precipitate; wash the precipitate three times alternately with 100g of anhydrous ethanol and 100g of deionized water, dry it under vacuum at 90℃ for 20h, pass it through a 325-mesh sieve, and seal it in a desiccator containing 4A molecular sieve to obtain cerium-doped zinc borate modified boron nitride nanosheets.
[0038] Preparation steps of phosphomolybdic acid intercalated modified magnesium aluminum lanthanum ternary hydrotalcite: Step B1: Dissolve 1.5g of lanthanum nitrate hexahydrate and 1.5g of trisodium citrate in 50g of deionized water that has been boiled to remove CO2, and stir at 40°C for 30min to obtain a lanthanum-citric acid pre-complexed solution; dissolve 20.0g of magnesium nitrate hexahydrate and 11.0g of aluminum nitrate nonahydrate in 150g of deionized water that has been boiled to remove CO2 to obtain a magnesium-aluminum salt solution; mix the lanthanum-citric acid pre-complexed solution and the magnesium-aluminum salt solution thoroughly to obtain a mixed metal salt solution; dissolve 15.0g of sodium hydroxide in 150g of deionized water that has been boiled to remove CO2 to obtain a mixed metal salt solution. An alkaline solution was prepared from deionized water that had been boiled to remove CO2. Under a constant temperature water bath at 75°C and nitrogen protection, a small amount of alkaline solution was added dropwise to a reaction flask containing 100g of deionized water that had been boiled to remove CO2, adjusting the initial pH to 10.5. Subsequently, a mixed metal salt solution and the remaining alkaline solution were added dropwise simultaneously and slowly using a double-dropping method to maintain the pH of the reaction system at 10.5±0.2. After the addition was completed, the flask was sealed and aged at 75°C for 28 hours. The precipitate was obtained by centrifugation. The precipitate was washed with deionized water until neutral to obtain the wet material of the hydrotalcite precursor.
[0039] Step B2: Dissolve 10.0g of phosphomolybdic acid in 150g of deionized water, add dropwise 10% sodium hydroxide aqueous solution to adjust the pH to 4.5, obtaining a phosphomolybdic acid buffer solution; disperse the wet hydrotalcite precursor in 100g of deionized water that has been bubbled with nitrogen to remove CO2, obtaining a suspension; under nitrogen protection, slowly add the phosphomolybdic acid buffer solution to the suspension, and continuously stir at 65℃ for 2 hours to carry out the intercalation reaction, maintaining the pH at 4.5; then add dropwise 10.0g of sodium hydroxide aqueous solution to adjust the pH to 4.5, obtaining a phosphomolybdic acid buffer solution. The pH was adjusted to 6.0 using a 5% sodium hydroxide aqueous solution, and the intercalation stabilization reaction was continued with stirring for 6 hours. After the reaction was completed, the precipitate was separated by centrifugation at 9000 r / min while hot. The precipitate was washed repeatedly with deionized water at 70℃ until the pH of the supernatant dropped to 7.5. The washed precipitate was vacuum dried at 80℃ for 18 hours, passed through a 325-mesh sieve, and sealed and stored in a desiccator containing 4A molecular sieve to obtain phosphomolybdic acid intercalated modified magnesium aluminum lanthanum ternary hydrotalcite.
[0040] Comparative Example 1 The specific implementation method is the same as in Example 1, except that γ-aminopropyltriethoxysilane is not added in step S1. The remaining steps and parameters are exactly the same as in Example 1.
[0041] Comparative Example 2 The specific implementation method is the same as in Example 1, except that cerium-doped zinc borate-modified boron nitride nanosheets are not added in step S1. The remaining steps and parameters are exactly the same as in Example 1.
[0042] Comparative Example 3 The specific implementation method is the same as in Example 1, except that phosphomolybdic acid intercalated modified magnesium aluminum lanthanum ternary hydrotalcite is not added in step S1. The remaining steps and parameters are exactly the same as in Example 1.
[0043] Performance testing The high-performance biomass flame-retardant composite fillers prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing according to the following method, which included the following steps: The fillers obtained in Examples 1-3 and Comparative Examples 1-3 were melt-blended with polypropylene (PP, melt index 3.0 g / 10 min) at a mass ratio of 20:80 in a twin-screw extruder. The temperatures of each section of the extruder were 170°C, 180°C, 190°C, 200°C, and 200°C (die head), respectively, and the screw speed was 150 r / min. The extrudate was cooled in a water bath and then granulated. The resulting granules were dried at 80°C for 4 hours and then injection molded into standard test specimens at an injection molding machine at an injection temperature of 200°C and a mold temperature of 40°C.
[0044] The limiting oxygen index (LOI) test uses an oxygen index meter. The sample size is 130mm×6.5mm×3.2mm. After igniting the sample at the top, the oxygen and nitrogen mixed gas flow is adjusted so that the flame front just reaches the 50mm mark or the oxygen concentration when the combustion lasts for 3 minutes is the LOI value. Five samples are tested in each group and the average value is taken.
[0045] The vertical flammability rating was determined based on the UL-94 vertical flammability method. The sample size was 125mm × 13mm × 3.2mm. The sample was vertically clamped above a Bunsen burner with a flame height of 20mm. The flame was applied to the lower end of the sample for 10 seconds and then removed. The duration of flaming combustion was recorded. If the flame went out, it was immediately applied again for 10 seconds and then removed. The duration of the second flaming combustion and the duration of the flaming combustion were recorded. At the same time, degreased cotton was placed at the lower end to observe whether the dripping material ignited the cotton. The V-0, V-1, or V-2 rating was determined based on the total combustion time and whether the cotton was ignited. Five samples were tested in each group.
[0046] Cone calorimetry analysis was performed using a cone calorimeter. The sample size was 100mm × 100mm × 4mm. The sample was placed horizontally in the sample cell after the non-heated surface was wrapped with aluminum foil. The thermal radiation power was set to 50kW / m². 2The igniter spark continuously ignites and releases gas. The data acquisition system automatically records the peak heat release rate (pHRR), total heat release (THR), and total smoke release (TSP). The average value of three samples in each test group is taken.
[0047] Tensile strength tests were conducted on a universal testing machine. The specimen was a type 1A dumbbell-shaped specimen with a gauge length of 50 mm and an initial clamping distance of 115 mm. A constant tensile rate of 50 mm / min was applied until the specimen broke. The maximum tensile stress was recorded as the tensile strength. The average value of 5 specimens in each group of tests was taken.
[0048] Unnotched impact strength was tested using a simply supported beam impact testing machine. The specimen size was 80mm×10mm×4mm. The specimen was placed horizontally on the support and a 4J energy pendulum was selected. The impact line was located at the center line of the wide face of the specimen and parallel to the thickness direction. The energy absorbed by the specimen during fracture was recorded, and the impact strength was obtained by normalizing the cross-sectional area per unit. Five specimens were tested in each group and the average value was taken.
[0049] Thermogravimetric analysis was performed using a thermogravimetric analyzer under a nitrogen atmosphere with a nitrogen flow rate of 50 mL / min. A sample of 5 mg was placed in an alumina crucible and heated from 35 °C to 800 °C at a heating rate of 20 °C / min. The temperature at which 5% mass loss was achieved (T5%) and the percentage of residual mass at 800 °C (carbon residue at 800 °C) were recorded. Each test was performed three times and the average value was taken.
[0050] Test results: Table 1: Test results of each embodiment and comparative example ; As shown in Table 1, the limiting oxygen index (LOI) of Examples 1-3 reached 36.5%, 34.8%, and 38.2%, respectively, all exceeding the industrial V-0 flame retardant threshold of 34.5%. All examples achieved V-0 vertical burning ratings, and their peak heat release rate (pHRR) showed a systematic decrease compared to Comparative Examples 1-3. Specifically, Example 3 had a pHRR of 265 kW / m³. 2 The comparison ratio 2 decreased by 32.4%, which indicates that the present invention, through the multi-element synergy of sodium lignosulfonate and phytic acid with cerium-doped zinc borate-modified boron nitride nanosheets and phosphomolybdic acid-intercalated modified magnesium aluminum lanthanum ternary hydrotalcite, forms a highly efficient and dense carbon layer in the condensed phase, which significantly delays the transfer of heat to the deep layers of the matrix and effectively isolates the outward dissipation of combustible gases.
[0051] Example 3 showed a high char residue rate of 41.0% at 800℃, while Comparative Example 2 only achieved 30.5%, a difference of over 10 percentage points. This more directly verifies that the coexistence of cerium-doped zinc borate-modified boron nitride nanosheets and phosphomolybdic acid-intercalated modified magnesium aluminum lanthanum ternary hydrotalcite has a significant catalytic effect on graphitization and char layer enhancement during the char formation process. The comparative examples lacking either inorganic phase resulted in a decrease in char residue rate, and Comparative Example 3, lacking the hydrotalcite phase, achieved a total smoke release (TSP) of 12.8 m³. 2 The result was the worst among all samples, indicating that the phosphomolybdic acid anions and hydrated structures between the hydrotalcite layers play a key role in diluting combustible gases and capturing free radicals in the gas phase.
[0052] Regarding compatibility and dispersibility, Examples 1-3, which employed in-situ bridging with γ-aminopropyltriethoxysilane, consistently maintained tensile strength and impact strength of 31.5-33.0 MPa and 5.1-5.7 kJ / m, respectively. 2 Between these parameters, it is significantly superior to Comparative Example 1, which lacks the coupling agent and has a strength of only 26.8 MPa and 4.2 kJ / m². 2 The performance and comparative data of mechanical properties directly prove that the coordination crosslinking constructed by silane molecules between biomass macromolecules and inorganic nanosheet surface active sites not only solves the inherent defect of nanofillers being prone to stacking and agglomeration due to excessively high specific surface energy, but also endows the composite filler with good interfacial compatibility and stress transfer ability between the composite filler and the polypropylene matrix, avoiding the prominent problem of system embrittlement and sharp drop in strength caused by the addition of large amounts of traditional flame retardant fillers.
[0053] The significant improvement in thermal stability of Examples 1-3 is also reflected in the T5% temperature. The T5% of Example 3 reached 283℃, which is 15℃ higher than that of Comparative Example 1. This is closely related to the ultra-high thermal stability and layer barrier effect of the cerium-doped zinc borate modified boron nitride nanosheets. After the cerium-doped zinc borate modified boron nitride nanosheets are uniformly dispersed, they can form a thermal barrier in the early stage of matrix heating, delaying the random breakage of matrix molecular chains and postponing the release of volatiles.
[0054] In summary, Examples 1-3 utilize γ-aminopropyltriethoxysilane under controlled weak acid-weak alkaline gradient conditions to achieve uniform anchoring and multi-element synergy at the molecular scale between biomass organic phase, cerium-doped zinc borate-modified boron nitride nanosheets, and phosphomolybdic acid-intercalated modified magnesium aluminum lanthanum ternary hydrotalcite. This approach not only overcomes the bottleneck of low efficiency in single flame retardant pathways by achieving a dual mechanism of condensed phase and gas phase linkage, but also overcomes the bottleneck of difficulty in effective dispersion of nanosheet materials due to surface inertia and strong interlayer stacking. Ultimately, at low addition levels, the materials are endowed with excellent flame retardant properties, low smoke release, and good mechanical retention, comprehensively solving the three key problems mentioned above in existing flame retardant fillers.
[0055] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.
Claims
1. A method for preparing a high-performance biomass flame-retardant composite filler, characterized in that the steps include... include: S1. By weight, add 10-30 parts of sodium lignosulfonate and 1-8 parts of phytic acid to a three-necked flask containing 400-800 parts of deionized water. Stir at 60-70℃ and adjust the pH to 4.0-5.0 to obtain a biomass dispersion. Disperse 0.5-1.5 parts of γ-aminopropyltriethoxysilane in 100-150 parts of an aqueous ethanol solution, and add 0.5-2 parts of glacial acetic acid dropwise to adjust the pH to 4.
0. Hydrolyze 5.0 at 25-40℃; adjust pH to 7.0-8.0, add 2.5-10 parts of cerium-doped zinc borate-modified boron nitride nanosheets and 2.5-10 parts of phosphomolybdic acid-intercalated modified magnesium aluminum lanthanum ternary hydrotalcite, and sonicate to obtain a mixed slurry; add biomass dispersion dropwise to the mixed slurry, stir, adjust temperature to 50-60℃, adjust pH to 5.5-6.5, stir to react, and obtain a reaction mixture; S2. Spray dry the reaction mixture and allow it to cool naturally to room temperature.
2. The preparation method of the high-performance biomass flame-retardant composite filler according to claim 1, characterized in that, In step S1, the stirring reaction time is 1.5-3 hours.
3. The method for preparing high-performance biomass flame-retardant composite filler according to claim 1, characterized in that, In step S2, the inlet air temperature of the spray dryer is 150-170℃ and the outlet air temperature is 75-85℃.
4. The preparation method of the high-performance biomass flame-retardant composite filler according to claim 1, characterized in that, The method for preparing the cerium-doped zinc borate-modified boron nitride nanosheets includes: A1. By weight, mix 3-8 parts of hexagonal boron nitride powder with 90-480 parts of urea, add to a ball mill, and ball mill to obtain a mixture; add the mixture to 200-400 parts of deionized water, centrifuge, wash, and vacuum dry to obtain a dry powder; dissolve 3-5 parts of zinc nitrate hexahydrate, 1.5-2.5 parts of boric acid, 0.15-0.6 parts of cerium nitrate hexahydrate, and 0.1-0.5 parts of trisodium citrate in 80-150 parts of deionized water to obtain a precursor solution; disperse the dry powder in the precursor solution, sonicate, stir, add sodium hydroxide aqueous solution, and adjust the pH to 4.5-5.5 for pre-complexation; add sodium hydroxide aqueous solution, and adjust the pH to 6.8-7.2 to obtain a suspension; transfer the suspension to a reaction vessel and carry out a hydrothermal reaction at 160-180℃ to obtain a reaction mixture; A2. Cool the reaction mixture to room temperature naturally, filter it to obtain a precipitate; wash the precipitate alternately with anhydrous ethanol and deionized water, and dry it under vacuum.
5. The method for preparing high-performance biomass flame-retardant composite filler according to claim 4, characterized in that, In step A1, the hydrothermal reaction is carried out at 160-180℃ for 12-18 hours.
6. The method for preparing high-performance biomass flame-retardant composite filler according to claim 4, characterized in that, In step A2, the vacuum drying temperature is 80-90℃.
7. The method for preparing high-performance biomass flame-retardant composite filler according to claim 1, characterized in that, The preparation method of the phosphomolybdic acid intercalated modified magnesium aluminum lanthanum ternary hydrotalcite includes: B1. By weight, dissolve 0.2-1.5 parts of lanthanum nitrate hexahydrate and 0.3-1.5 parts of trisodium citrate in 20-50 parts of deionized water and stir at 30-40℃ to obtain a lanthanum-citric acid pre-complexed solution; dissolve 15-20 parts of magnesium nitrate hexahydrate and 7-11 parts of aluminum nitrate nonahydrate in 80-150 parts of deionized water to obtain a magnesium-aluminum salt solution; mix the lanthanum-citric acid pre-complexed solution with the magnesium-aluminum salt solution to obtain a mixed metal salt solution; dissolve 5-15 parts of sodium hydroxide in 50-150 parts of deionized water to obtain an alkaline solution; under a nitrogen atmosphere at 55-75℃, add the alkaline solution dropwise to 50-100 parts of deionized water, followed by the mixed metal salt solution, maintaining the pH at 9.8-10.5; after the addition is complete, age the solution at 55-75℃, centrifuge to obtain a precipitate; wash the precipitate with deionized water to obtain a washed precipitate. B2. Dissolve 3-10 parts of phosphomolybdic acid in 80-150 parts of deionized water, add sodium hydroxide aqueous solution dropwise to adjust the pH to 4.0-4.5, and obtain a phosphomolybdic acid buffer solution; disperse the washed precipitate in 50-100 parts of deionized water to obtain a suspension; add the phosphomolybdic acid buffer solution to the suspension, and carry out the intercalation reaction under nitrogen protection at 45-65℃ with stirring, maintaining the pH at 4.0-4.5; add sodium hydroxide aqueous solution dropwise to adjust the pH to 5.5-6.0, and carry out the intercalation stabilization reaction with stirring; after the reaction is completed, centrifuge to obtain the precipitate; wash the precipitate with deionized water at 50-70℃; and vacuum dry.
8. The method for preparing high-performance biomass flame-retardant composite filler according to claim 7, characterized in that, In step B1, the aging reaction time at 55-75℃ is 20-28 hours.
9. The method for preparing high-performance biomass flame-retardant composite filler according to claim 7, characterized in that, In step B2, the vacuum drying temperature is 60-80℃.
10. A high-performance biomass flame-retardant composite filler, characterized in that, The high-performance biomass flame-retardant composite material filler is prepared by the method according to any one of claims 1-9.