High-temperature-resistant and flame-retardant bio-based polyurethane foam and preparation method thereof

Abstract

The invention relates to the technical field of bio-based polyurethane foam, in particular to high-temperature-resistant and flame-retardant bio-based polyurethane foam and a preparation method thereof.The bio-based polyurethane foam is prepared by mixing a component A and a component B according to the mass ratio of 1: 1.2-1.35; wherein the component A is prepared from 75 to 85 parts of a bio-based polyol composition, 8 to 10 parts of a foaming agent, 0.8 to 1.2 parts of a catalyst, 10 to 12 parts of a flame retardant, 1.0 to 1.5 parts of an antistatic agent, 2.5 to 3.0 parts of a functional auxiliary agent, 0.03 to 0.08 part of a visual auxiliary agent, 0.5 to 1.0 part of an antibacterial agent and 0.3 to 0.5 part of a rare earth modified auxiliary agent; and the component B is prepared by mixing diphenylmethane diisocyanate and hexamethylene diisocyanate. The preparation method comprises the following steps: preparing the rare earth ion pre-dispersion liquid, sequentially adding all the materials into a stirring kettle, stirring to obtain the component A and the component B, and mixing the component A and the component B to obtain the bio-based polyurethane foam. The invention solves the problem of single function of bio-based polyurethane foam.

Description

Technical Field

[0001] This invention relates to the field of polyurethane foam technology, and in particular to a high-temperature resistant, flame-retardant bio-based polyurethane foam and its preparation method. Background Technology

[0002] With the increasing demands for environmental friendliness and safety in fields such as emergency response to hazardous chemical leaks, fire protection in high-end buildings, and protection against extreme environments, polyurethane foam has become a core application material due to its excellent adsorption, sealing, and molding properties. However, traditional polyurethane foam relies on fossil-based polyol raw materials, which have drawbacks such as non-degradability and heavy environmental burden. Furthermore, conventional flame-retardant modification with the addition of halogenated flame retardants can easily lead to secondary risks such as high smoke density and the release of toxic gases. At the same time, its high-temperature resistance is insufficient, typically with a long-term operating temperature of ≤80℃. In high-temperature leak scenarios, it is prone to softening and collapse, making it difficult to meet complex emergency needs. Although bio-based polyurethane foam has become a research hotspot due to the environmental advantages of renewable raw materials such as castor oil and lignin, the low hydroxyl density and insufficient cross-linking degree in the molecular structure of natural bio-based raw materials make it difficult to improve its high-temperature resistance and flame-retardant properties. Moreover, in existing modification schemes, the addition of a single flame retardant can easily damage the foam pore structure, leading to a decrease in adsorption capacity. The balance between improving high-temperature stability and retaining bio-based content has not yet been effectively resolved.

[0003] Chinese Patent Application Publication No. CN111479838A discloses a flame-retardant rigid polyurethane foam, relating to a mixture containing triurethane triol and components selected from polyether polyols, polyester polyols, polyether carbonate polyols, and polyether ester polyols, and a method for producing a rigid PUR / PIR foam containing: A1 isocyanate reactive component, A2 flame retardant, A3 blowing agent, A4 catalyst, A5 optional auxiliaries and additives, and B organic polyisocyanate component; component A1 contains triurethane triol A1.1 and compound A1.2 selected from polyether polyols, polyester polyols, polyether carbonate polyols, and polyether ester polyols.

[0004] The existing technology also has the following problems: traditional polyurethane foam generally relies too much on petrochemical raw materials, resulting in poor environmental performance; the flame retardant system has low efficiency, is prone to decomposition and failure at high temperatures, and is accompanied by the release of toxic smoke; it lacks weather resistance and chemical corrosion resistance, and is prone to aging and pulverization in complex or extreme environments; and it has limited functionality, making it difficult to simultaneously meet multiple requirements such as high-efficiency adsorption, antistatic properties, and long-lasting antibacterial effects. Summary of the Invention

[0005] Therefore, this invention provides a high-temperature resistant, flame-retardant bio-based polyurethane foam and its preparation method, in order to overcome the problem that existing bio-based polyurethane foams have limited functionality and cannot simultaneously meet multiple requirements such as high-efficiency adsorption, antistatic properties, and long-lasting antibacterial effects.

[0006] To achieve the above objectives, on the one hand, the present invention provides a high-temperature resistant, flame-retardant bio-based polyurethane foam, wherein the bio-based polyurethane foam is made by mixing component A and component B in a mass ratio of 1:1.2 to 1.35; Component A consists of the following raw materials in parts by weight: The composition comprises 75-85 parts of a bio-based polyol composition, 8-10 parts of a foaming agent, 0.8-1.2 parts of a catalyst, 10-12 parts of a flame retardant, 1.0-1.5 parts of an antistatic agent, 2.5-3.0 parts of a functional additive, 0.03-0.08 parts of a visualization additive, 0.5-1.0 parts of an antibacterial agent, and 0.3-0.5 parts of a rare earth modifying additive. The bio-based polyol composition includes castor oil, lignin-modified polyether polyol, and polylactic acid-modified polyol. The rare earth modifying additive includes lanthanum nitrate and nano-cerium oxide. Component B is prepared by mixing 110-120 parts by weight of diphenylmethane diisocyanate (MDI-50) and 10-15 parts by weight of hexamethylene diisocyanate (HDI).

[0007] Furthermore, the mass ratio of the castor oil, the lignin-modified polyether polyol, and the polylactic acid-modified polyol is 40:25:10.

[0008] Furthermore, the mass ratio of the lanthanum nitrate to the nano-cerium oxide is 0.25:0.15.

[0009] Furthermore, the foaming agent comprises distilled water and cyclopentane in a mass ratio of 5:3.

[0010] Furthermore, the catalyst comprises dibutyltin dilaurate and triethylenediamine in a mass ratio of 0.6:0.4.

[0011] Furthermore, the flame retardant comprises ammonium polyphosphate and a modified starch-based flame retardant in a mass ratio of 8:3.

[0012] Furthermore, the antistatic agent is hexadecyltrimethylammonium bromide, and the visualization aid is bromothymol blue.

[0013] Furthermore, the functional additives include silane coupling agent KH-550 and polysiloxane foam stabilizer L-580 in a mass ratio of 1.5:1.1, and the antibacterial agent is chitosan with a degree of deacetylation greater than or equal to 90%.

[0014] Furthermore, the bio-based polyurethane foam has an oxygen index greater than or equal to 30%, a thermal decomposition temperature greater than or equal to 240°C, a soil degradation rate greater than or equal to 80%, and an adsorption ratio greater than or equal to 25 times.

[0015] On the other hand, the present invention also provides a method for preparing high-temperature resistant, flame-retardant bio-based polyurethane foam, comprising: Step S1: Lanthanum nitrate and distilled water are used to prepare a lanthanum nitrate pre-dispersion, and nano-cerium oxide and castor oil are used to prepare a nano-cerium oxide pre-dispersion. Step S2: Castor oil, lignin-modified polyether polyol and polylactic acid-modified polyol are added to the vacuum stirred tank in sequence. After stirring evenly, the lanthanum nitrate pre-dispersion and the nano-cerium oxide pre-dispersion are injected into the vacuum stirred tank at an injection rate of 5 mL / min. Step S3: After stirring evenly, add distilled water and cyclopentane to the vacuum stirred vessel in sequence, heat to 40°C and stir evenly. Step S4: After cooling to 25°C, add catalyst, flame retardant, antistatic agent, functional additive, bromothymol blue and chitosan in sequence, stir evenly and degas to obtain component A; Step S5: Inject MDI-50 and HDI into a vacuum stirred tank and stir until homogeneous to obtain component B; Step S6: Add component A and component B to the high-pressure foaming spray gun in proportion, and obtain bio-based polyurethane foam after foaming and curing.

[0016] Compared with existing technologies, the beneficial effects of the embodiments of the present invention are as follows: the bio-based polyurethane foam provided by the present invention uses castor oil, lignin-modified polyols, and polylactic acid (PLA)-modified polyols as the core to construct a bio-based framework, which significantly reduces the dependence of traditional foams on fossil resources. The material exhibits good environmental compatibility at the end of its life cycle, and experiments show that it has certain biodegradation potential in soil. At the same time, the entire formulation system emphasizes the use of environmentally friendly additives, realizing an environmentally friendly design throughout the entire chain from raw materials to disposal.

[0017] Furthermore, the bio-based polyurethane foam provided by this invention achieves multifunctional, highly efficient integration and performance breakthroughs through ingenious component synergy. Rare earth modifying agents, acting as key synergistic centers, are deeply coupled with components such as flame retardants, catalysts, and antibacterial agents, enabling the foam to simultaneously possess excellent flame retardancy, efficient adsorption performance, and long-lasting antistatic and antibacterial capabilities. This allows the bio-based polyurethane foam to simultaneously meet multiple needs such as safety, hygiene, and pollution adsorption in complex scenarios.

[0018] Furthermore, the bio-based polyurethane foam provided by this invention not only possesses good mechanical strength and cushioning resilience, but also high thermal stability and weather resistance. The synergistic effect between the components is not a simple additive effect, but rather produces a "1+1>2" enhancement effect, enabling the foam to maintain the environmental advantages of bio-based materials while reaching or even surpassing the level of some traditional petroleum-based functional foams in key performance indicators. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation method of high-temperature resistant, flame-retardant bio-based polyurethane foam according to an embodiment of the present invention; Figure 2 This is a SEM image of the bio-based polyurethane foam from Example 1 of the present invention; Figure 3 This is the SEME diagram of the bio-based polyurethane foam of Comparative Example 1 of the present invention. Detailed Implementation

[0020] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0021] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0022] This invention relates to a high-temperature resistant, flame-retardant bio-based polyurethane foam, wherein the bio-based polyurethane foam is prepared by mixing component A and component B in a mass ratio of 1:1.2 to 1.35. Component A consists of the following raw materials in parts by weight: The composition comprises 75-85 parts of a bio-based polyol composition, 8-10 parts of a foaming agent, 0.8-1.2 parts of a catalyst, 10-12 parts of a flame retardant, 1.0-1.5 parts of an antistatic agent, 2.5-3.0 parts of a functional additive, 0.03-0.08 parts of a visualization additive, 0.5-1.0 parts of an antibacterial agent, and 0.3-0.5 parts of a rare earth modifying additive. The bio-based polyol composition includes castor oil, lignin-modified polyether polyol, and polylactic acid-modified polyol, wherein the mass ratio of castor oil, lignin-modified polyether polyol, and polylactic acid-modified polyol is 40:25:10. The rare earth modifying agent includes lanthanum nitrate and nano-cerium oxide, wherein the mass ratio of lanthanum nitrate to nano-cerium oxide is 0.25:0.15; The foaming agent comprises distilled water and cyclopentane in a mass ratio of 5:3; The catalyst comprises dibutyltin dilaurate (DBTDL) and triethylenediamine (TEDA) in a mass ratio of 0.6:0.4; The flame retardant comprises ammonium polyphosphate (APP) and a modified starch-based flame retardant in a mass ratio of 8:3; The antistatic agent is hexadecyltrimethylammonium bromide (CTAB), and the visualization aid is bromothymol blue. The functional additives include silane coupling agent KH-550 and polysiloxane foam stabilizer L-580 in a mass ratio of 1.5:1.1, and the antibacterial agent is chitosan with a degree of deacetylation greater than or equal to 90%. Component B is prepared by mixing 110-120 parts by weight of diphenylmethane diisocyanate (MDI-50) and 10-15 parts by weight of hexamethylene diisocyanate (HDI).

[0023] In this embodiment of the invention, the bio-based polyol composition, through the synergistic effect of castor oil, lignin-modified polyether polyol, and polylactic acid-modified polyol, constitutes the cornerstone of foam performance. Specifically, castor oil, as a flexible segment, provides excellent hydrophobicity and oleophilicity, as well as segment flexibility, which is the basis for the foam's high elasticity and selective adsorption capacity. The lignin-modified polyether polyol, rich in rigid aromatic ring structures, acts as a rigidity reinforcing unit, effectively inhibiting foam shrinkage and pore wall collapse, providing skeletal support for the formation of a stable, high-porosity three-dimensional network. The PLA-modified polyol contributes high intrinsic strength and regularity, further enhancing the overall rigidity, mechanical strength, and dimensional stability of the foam. During the foaming and curing process, the flexible castor oil segments interweave between the rigid network composed of lignin and PLA, playing a crucial role in toughening and stress buffering, effectively preventing brittle fracture of the foam due to excessive rigidity. Meanwhile, the rigid support of lignin and PLA ensures that the flexible segments of castor oil do not cause irreversible structural collapse when adsorbed, swollen, or under pressure, thus achieving an ideal structure that combines rigidity and flexibility. This structure allows the foam to withstand certain loads and deformations while maintaining the integrity of its porous adsorption structure over a long period.

[0024] Specifically, the hydrophobic long chains of castor oil possess an intrinsic affinity for nonpolar oils and organic solvents, serving as capture sites for oil-water separation and adsorption of organic pollutants. Lignin-modified polyether polyols, due to their polyphenolic hydroxyl structure and the polar groups introduced after modification, can enhance their affinity for polar gases (such as...) through hydrogen bonding and other interactions. The adsorption of rare earth ions, such as those found in some polar liquids, and the resulting stable open-pore structure, greatly increases the specific surface area and mass transport channels; rare earth ions, such as... The introduction of [a certain factor] is a key synergistic factor. It can coordinate with oxygen-containing functional groups in lignin and also interact weakly with castor oil segments, acting as a molecular anchor.

[0025] Rare earth ions act as a bridge, organically integrating the hydrophobic adsorption sites of castor oil with the polar adsorption sites and high specific surface area network provided by lignin. For complex pollutants, such as oils containing polar groups or oil-water-heavy metal mixtures, multi-mode synergistic adsorption can be achieved: the castor oil backbone is responsible for capturing the organic phase, while the polar sites of lignin and rare earth ions can complex heavy metals or polar molecules, thereby significantly improving adsorption capacity, selectivity, and purification ability for complex media. The rigidity provided by the PLA segments ensures that the entire network does not loosen and fail during adsorption swelling. Simultaneously, PLA-modified polyols endow the material with biodegradable potential, contributing to its environmentally friendly properties; lignin, as a natural UV and antioxidant, enhances the foam's weather resistance and delays photo / oxygen aging; castor oil exhibits good resistance to hydrolysis and acid / alkali corrosion; and nano-cerium oxide, as a rare earth component, possesses excellent free radical scavenging ability and chemical stability. In practical implementation, the anti-aging properties of lignin and the corrosion resistance of castor oil jointly ensure the structural stability of the foam, while nano-cerium oxide (… This further eliminates free radicals that may be generated during the degradation process, inhibiting the unexpected rapid embrittlement of the PLA component, thereby significantly extending the service life of the foam in harsh environments. Once the foam has completed its mission and enters the disposal stage, the controlled degradation characteristics of the PLA component are activated in specific environments, such as composting, while the natural origin of lignin and castor oil ensures the environmental compatibility of the degradation products. The combination of these three components with rare earth stabilizers achieves a perfect balance between long-term stability and ultimate environmental remediation.

[0026] Specifically, the foaming agent includes distilled water and cyclopentane. Distilled water, as a chemical foaming agent, reacts with isocyanate to generate carbon dioxide gas, which is the basic driving force for the formation of the foam's main cells. Cyclopentane, as a physical foaming agent, provides additional expansion force through its vaporization process. Together, they achieve an ideal foaming ratio and a lower overall density.

[0027] Specifically, the catalysts include DBTDL and TEDA. DBTDL primarily catalyzes the gelation reaction of isocyanates with hydroxyl groups, i.e., the chain growth reaction, promoting molecular chain growth and network formation. TEDA primarily catalyzes the foaming reaction of isocyanates with water and the formation of urea bonds, driving gas generation. The synergistic effect of these two catalysts precisely balances the foaming-gelation rate, preventing structural collapse or cracking caused by asynchronous reactions, and ensuring uniform foam pore size and overall integrity. The introduction of rare earth ions further synergizes with this catalytic system, maintaining high reactivity while reducing the total catalyst dosage.

[0028] Specifically, the flame retardant includes APP and a modified starch-based flame retardant. APP, as a highly efficient phosphorus-nitrogen flame retardant, promotes char formation, isolates oxygen, and dilutes combustible gases when heated. The modified starch-based flame retardant, derived from biomass, enhances the density and stability of the char layer formed by APP through its charred layer. Both APP and rare earth ions work synergistically, forming coordination compounds with APP and other components, improving the quality and thermal stability of the char layer, thus constructing a highly efficient and environmentally friendly flame retardant system with dual effects in both the gas and condensed phases.

[0029] Specifically, the antistatic agent is CTAB. As a cationic surfactant, CTAB can migrate to the foam surface and adsorb ambient moisture through its hydrophilic groups to form a conductive layer, thereby dissipating static charge. In synergy with positively charged rare earth ions, it can further optimize charge distribution and enhance the durability and environmental humidity dependence of the antistatic effect.

[0030] Specifically, the visualization aid is bromothymol blue. As a pH-sensitive dye, when the foam environment in which it is located adsorbs acidic or alkaline substances, its pH changes, resulting in a noticeable color change. This characteristic allows for intuitive and real-time monitoring of the foam's adsorption saturation state or its contact with specific chemicals.

[0031] Specifically, the functional additives include silane coupling agents KH-550 and L-580. KH-550 improves the interfacial compatibility and adhesion between inorganic fillers, such as flame retardants and rare earth nanoparticles, and the organic polyurethane matrix. L-580 reduces surface tension at the gas-liquid interface, controlling cell merging and coarsening to ensure the formation of fine, uniform closed-cell or open-cell structures. The two work synergistically, and together with the rare earth pre-dispersion liquid, to ensure the uniform and stable microstructure of the composite foam material.

[0032] Specifically, the antibacterial agent is chitosan with a degree of deacetylation greater than or equal to 90%. As a natural cationic polysaccharide, chitosan's antibacterial mechanism primarily lies in disrupting the integrity of bacterial cell membranes. A high degree of deacetylation means more free amino groups, thereby enhancing its positive charge and antibacterial activity. Synergistically with rare-earth nanoparticles possessing redox activity, chitosan, acting as a lead cell disruptor, with its high-density positively charged molecules, first firmly binds to the negatively charged bacterial cell membrane surface through electrostatic adsorption. This process not only directly interferes with the membrane potential, but its molecular chains can also insert into and disrupt the arrangement of the lipid bilayer, increasing membrane permeability and causing intracellular leakage. This opens a pathway for subsequent attacks. Rare-earth nanoparticles, acting as deep-penetrating agents, further facilitate this process. Based on the initial disruption of cell membrane integrity and permeability by chitosan, the tiny rare-earth nanoparticles more easily approach and attach to the damaged membrane surface, and even enter the cell interior through enlarged membrane pores. Chitosan's initial effect significantly reduces the energy barrier and physical obstacles for rare earth particles to approach and penetrate cells, allowing chemical attacks to reach the vital organs more efficiently. Chitosan primarily causes physical cell death by physically disrupting membrane structures. CeO2 nanoparticles, due to their CeO2 content... 3+ / Ce 4+ The coexistence of redox pairs can mimic the activity of peroxidases, catalyzing the production of highly reactive oxygen species such as hydroxyl radicals (·OH) from substances in the environment. ROS can indiscriminately oxidize key life-sustaining substances within cells, such as proteins, lipids, and DNA, leading to cellular metabolic disorders and programmed cell death. The combination of these two factors achieves a comprehensive, multi-target attack from the outside in, making it difficult for bacteria to survive through a single drug resistance mechanism.

[0033] Specifically, component B is composed of a mixture of diphenylmethane diisocyanate (MDI-50) and hexamethylene diisocyanate (HDI). MDI-50, with its high reactivity and rigid aromatic structure, is the core component responsible for the rigidity and strength of the foam matrix, providing excellent mechanical strength and chemical resistance. HDI, on the other hand, provides flexible aliphatic long chains, imparting good toughness, hydrolysis resistance, and weather resistance to the foam. Both react with the bio-based polyols and rare earth additives in component A to jointly construct a three-dimensional polyurethane network framework that is moderately rigid yet flexible, highly durable, and functional. The synergistic use of MDI and HDI achieves an optimal balance between the overall mechanical properties and durability of the foam.

[0034] Specifically, the bio-based polyurethane foam has an oxygen index greater than or equal to 30%, a thermal decomposition temperature greater than or equal to 240°C, a soil degradation rate greater than or equal to 80% after 180 days, and an adsorption ratio greater than or equal to 25 times.

[0035] Please see Figure 1 As shown, it is a flowchart of the preparation method of high temperature resistant and flame retardant bio-based polyurethane foam according to an embodiment of the present invention.

[0036] The method for preparing high-temperature resistant, flame-retardant bio-based polyurethane foam according to embodiments of the present invention includes: Step S1: Lanthanum nitrate and distilled water are used to prepare a lanthanum nitrate pre-dispersion, and nano-cerium oxide and castor oil are used to prepare a nano-cerium oxide pre-dispersion. Step S2: Castor oil, lignin-modified polyether polyol and polylactic acid-modified polyol are added to the vacuum stirred tank in sequence. After stirring evenly, the lanthanum nitrate pre-dispersion and the nano-cerium oxide pre-dispersion are injected into the vacuum stirred tank at an injection rate of 5 mL / min. Step S3: After stirring evenly, add distilled water and cyclopentane to the vacuum stirred vessel in sequence, heat to 40°C and stir evenly. Step S4: After cooling to 25°C, add catalyst, flame retardant, antistatic agent, functional additive, bromothymol blue and chitosan in sequence, stir evenly and degas to obtain component A; Step S5: Inject MDI-50 and HDI into a vacuum stirred tank and stir until homogeneous to obtain component B; Step S6: Add component A and component B to the high-pressure foaming spray gun in proportion, and obtain bio-based polyurethane foam after foaming and curing.

[0037] Specifically, in step S1, lanthanum nitrate and distilled water are weighed at a mass ratio of 1:8, placed in a beaker, and stirred at 25°C and 300 r / min for 15 min-20 min until completely dissolved to obtain a lanthanum nitrate pre-dispersion.

[0038] Specifically, in step S2, nano-cerium oxide and castor oil are weighed at a mass ratio of 1:20, poured into an ultrasonic disperser, and the temperature is set to 30℃, the power to 400W, and the frequency to 40kHz. The mixture is ultrasonically dispersed for 30-40 minutes, and stirred once every 10 minutes at a speed of 500r / min to ensure uniform particle size dispersion. The particle size is measured by a laser particle size analyzer, and D90≤200nm is obtained to obtain a nano-cerium oxide pre-dispersion.

[0039] Specifically, in step S2, the remaining castor oil, lignin-modified polyether polyol, and polylactic acid (PLA)-modified polyol are added to the vacuum stirring vessel. The vessel door is closed, and nitrogen gas is introduced at a flow rate of 5 L / min to replace the air in the vessel three times. The stirring is then started at a speed of 500 r / min and stirred at 25°C for 10-15 minutes until the mixture is uniform and transparent. The viscosity is confirmed to be ≥1200 mPa·s by visual observation and viscosity testing to confirm whether the stirring is uniform.

[0040] After stirring evenly, maintain a rotation speed of 500 r / min, and slowly inject the lanthanum nitrate pre-dispersion and nano-cerium oxide pre-dispersion prepared in step S1 into the vacuum stirred tank at an injection rate of 5 mL / min. Increase the stirring speed to 800 r / min, stir at 25℃ for 10 min-15 min, and confirm that the stirring is even when there are no white agglomerated particles.

[0041] Specifically, in step S3, the remaining distilled water and cyclopentane are added sequentially to the vacuum stirred tank, the temperature control device is turned on, the temperature is raised to 40°C, the speed is maintained at 800 r / min, and the mixture is stirred for 20 min-30 min. During this period, the uniformity of the system is checked every 5 min to ensure that no cyclopentane droplets are precipitated.

[0042] Specifically, in step S4, the temperature of the vacuum stirring vessel is reduced to 25°C, and the rotation speed is maintained at 600 r / min. DBTDL, TEDA, APP, modified starch-based flame retardant, and CTAB are added sequentially. After each additive is added, the mixture is stirred for 3 minutes to ensure uniform dispersion. Then, silane coupling agent KH-550, polysiloxane foam stabilizer L-580, bromothymol blue, and chitosan are added. The rotation speed is adjusted to 400 r / min, and the mixture is stirred for 5 min-10 min to avoid damaging the chitosan structure due to high rotation speed.

[0043] Specifically, in step S4, after stirring is completed, nitrogen is turned off, the vacuum system is turned on, the vacuum degree inside the vessel is evacuated to -0.08MPa, the rotation speed is maintained at 200r / min, and degassing is performed for 15min-20min until no obvious bubbles rise in the vacuum stirring vessel, thus obtaining component A. After degassing is completed, the pressure is restored to normal, and component A is quickly transferred to a corrosion-resistant container with a sealed inner wall coated with polytetrafluoroethylene, and stored in a dark and cool place.

[0044] Specifically, in step S5, MDI-50 is slowly injected into the stirred tank at an injection rate of 10 mL / min, stirring is started at a speed of 300 r / min for 5 min-10 min, and then HDI is slowly added at the same rate while maintaining a speed of 300 r / min and stirring at 25°C for 10 min-15 min. During this period, nitrogen gas is continuously introduced at a flow rate of 3 L / min to prevent isocyanate from contacting air, thus obtaining component B.

[0045] Specifically, in step S6, the high-pressure foaming spray gun needs to be cleaned with anhydrous ethanol in advance to ensure that there are no residual impurities. The stirring speed is adjusted to 3500-4000 r / min and the pressure is 0.3-0.4 MPa. Component A and component B are poured into the two raw material tanks of the high-pressure foaming spray gun according to the mass ratio. After turning on the stirring function, component A and component B are fully mixed in the mixing chamber for 30-60 seconds before being sprayed out. After foaming and curing, bio-based polyurethane foam is obtained.

[0046] The present invention will be illustrated and explained below through specific embodiments.

[0047] Example 1

[0048] Raw material components: Component A (parts by weight): 40 parts castor oil, 25 parts lignin-modified polyether polyol, 10 parts PLA-modified polyol, 5 parts distilled water, 3 parts cyclopentane, 0.6 parts DBTDL, 0.4 parts TEDA, 8 parts ammonium polyphosphate APP, 3 parts modified starch-based flame retardant, 1.2 parts CTAB, 1.5 parts silane coupling agent KH-550, 1.1 parts polysiloxane foam stabilizer L-580, 0.05 parts bromothymol blue, 0.8 parts chitosan with a degree of deacetylation ≥90%, 0.25 parts lanthanum nitrate, and 0.15 parts nano-cerium oxide.

[0049] Component B (parts by weight): MDI-50 115 parts, HDI 12 parts.

[0050] The mass ratio of component A to component B is 1:1.28.

[0051] Preparation method: Preparation of pre-dispersion: 0.25 parts of lanthanum nitrate were mixed with 2 parts (from a total of 5 parts) of distilled water and stirred at 25°C and 300 rpm for 18 min to obtain a lanthanum nitrate pre-dispersion. 0.15 parts of nano-cerium oxide were mixed with 3 parts (from a total of 40 parts) of castor oil and ultrasonically dispersed at 30°C, 400 W, and 40 kHz for 35 min, with stirring at 500 rpm for 1 min every 10 min to obtain a nano-cerium oxide pre-dispersion with D90 ≤ 200 nm.

[0052] Preparation of Component A: Add the remaining castor oil (37 parts), lignin-modified polyether polyol (25 parts), and PLA-modified polyol (10 parts) to a vacuum stirred tank. After nitrogen purging, stir at 500 rpm and 25°C for 12 min until homogeneous. While stirring, inject the two pre-dispersions at a rate of 5 mL / min, increase the speed to 800 rpm, and stir for 12 min until no agglomeration occurs. Add the remaining distilled water (3 parts) and cyclopentane (3 parts) sequentially, raise the temperature to 40°C, and stir at 800 rpm for 25 min. Cool to 25°C, and add DBTDL, TEDA, APP, modified starch-based flame retardant, and CTAB sequentially, stirring for 3 min after each addition. Then add KH-550, L-580, bromothymol blue, and chitosan, and stir at 400 rpm for 8 min. Finally, evacuate to -0.08 MPa and degas at 200 rpm for 18 min to obtain Component A.

[0053] Preparation of component B: MDI-50 and HDI were slowly added to another stirred tank in sequence, and stirred continuously with nitrogen at 300 r / min and 25℃ for 12 min to obtain component B.

[0054] Foaming and molding: Add components A and B to a cleaned high-pressure foaming spray gun in proportion, set the speed to 3800 r / min and the pressure to 0.35 MPa, mix for 45 seconds and then spray out. After curing, bio-based polyurethane foam is obtained.

[0055] Example 2 Raw material components: Component A (parts by weight): 42 parts castor oil, 23 parts lignin-modified polyether polyol, 10 parts PLA-modified polyol, 4.5 parts distilled water, 3.5 parts cyclopentane, 0.55 parts DBTDL, 0.45 parts TEDA, 7 parts APP, 3.5 parts modified starch-based flame retardant, 1.0 part CTAB, 1.8 parts KH-550, 1.0 part L-580, 0.03 parts bromothymol blue, 1.0 part chitosan, 0.2 parts lanthanum nitrate, and 0.1 parts nano-cerium oxide.

[0056] Component B (parts by weight): MDI-50 110 parts, HDI 10 parts.

[0057] The mass ratio of component A to component B is 1:1.2.

[0058] Preparation method: Same as in Example 1, but the parameters are adjusted accordingly based on the amount of raw materials in this example.

[0059] Example 3 Raw material components: Component A (parts by weight): 38 parts castor oil, 27 parts lignin-modified polyether polyol, 10 parts PLA-modified polyol, 5.5 parts distilled water, 2.5 parts cyclopentane, 0.65 parts DBTDL, 0.35 parts TEDA, 9 parts APP, 2.5 parts modified starch-based flame retardant, 1.5 parts CTAB, 1.2 parts KH-550, 1.3 parts L-580, 0.08 parts bromothymol blue, 0.5 parts chitosan, 0.3 parts lanthanum nitrate, and 0.2 parts nano-cerium oxide.

[0060] Component B (parts by weight): 120 parts MDI-50, 15 parts HDI.

[0061] The mass ratio of component A to component B is 1:1.35.

[0062] Preparation method: Same as in Example 1, but the parameters are adjusted accordingly based on the amount of raw materials in this example.

[0063] Example 4 Raw material components: Component A (parts by weight): Castor oil 45 parts, lignin-modified polyether polyol 22 parts, PLA-modified polyol 8 parts, distilled water 5.2 parts, cyclopentane 3.2 parts, DBTDL 0.5 parts, TEDA 0.3 parts, APP 7.5 parts, modified starch-based flame retardant 3.0 parts, CTAB 1.0 part, KH-550 1.4 parts, L-580 1.3 parts, bromothymol blue 0.04 parts, chitosan 0.6 parts, lanthanum nitrate 0.18 parts, nano-cerium oxide 0.12 parts.

[0064] Component B (parts by weight): MDI-50 105 parts, HDI 18 parts.

[0065] The mass ratio of component A to component B is 1:1.22.

[0066] Preparation method: Same as in Example 1, but the parameters are adjusted accordingly based on the amount of raw materials in this example.

[0067] Example 5 Raw material components: Component A (parts by weight): 38 parts castor oil, 26 parts lignin-modified polyether polyol, 11 parts PLA-modified polyol, 4.8 parts distilled water, 2.8 parts cyclopentane, 0.7 parts DBTDL, 0.5 parts TEDA, 8.5 parts APP, 2.8 parts modified starch-based flame retardant, 1.3 parts CTAB, 1.6 parts KH-550, 1.0 part L-580, 0.06 parts bromothymol blue, 0.9 parts chitosan, 0.28 parts lanthanum nitrate, and 0.17 parts nano-cerium oxide.

[0068] Component B (parts by weight): 118 parts MDI-50, 11 parts HDI.

[0069] The mass ratio of component A to component B is 1:1.32.

[0070] Preparation method: Same as in Example 1. In step S6, the stirring speed of the mixing chamber of the high-pressure foaming spray gun is reduced to 3500 r / min, and the other parameters are adjusted accordingly based on the amount of raw materials in this example.

[0071] Example 6 Raw material components: Component A (parts by weight): Castor oil 41 parts, lignin-modified polyether polyol 24 parts, PLA-modified polyol 12 parts, distilled water 5.0 parts, cyclopentane 3.0 parts, DBTDL 0.58 parts, TEDA 0.42 parts, APP 9.0 parts, modified starch-based flame retardant 3.2 parts, CTAB 1.1 parts, KH-550 1.7 parts, L-580 1.2 parts, bromothymol blue 0.05 parts, chitosan 0.7 parts, lanthanum nitrate 0.22 parts, nano-cerium oxide 0.25 parts.

[0072] Component B (parts by weight): MDI-50 112 parts, HDI 13 parts.

[0073] The mass ratio of component A to component B is 1:1.25. Preparation method: Same as in Example 1, but the parameters are adjusted accordingly based on the amount of raw materials in this example.

[0074] Example 7 Raw material components: Component A (parts by weight): Castor oil 43 parts, lignin-modified polyether polyol 28 parts, PLA-modified polyol 9 parts, distilled water 5.5 parts, cyclopentane 2.5 parts, DBTDL 0.52 parts, TEDA 0.38 parts, APP 8.0 parts, modified starch-based flame retardant 3.0 parts, CTAB 1.4 parts, KH-550 1.3 parts, L-580 1.15 parts, bromothymol blue 0.07 parts, chitosan 0.5 parts, lanthanum nitrate 0.35 parts, nano-cerium oxide 0.1 parts.

[0075] Component B (parts by weight): MDI-50 116 parts, HDI 10 parts.

[0076] The mass ratio of component A to component B is 1:1.30.

[0077] Preparation method: Same as in Example 1, but the parameters are adjusted accordingly based on the amount of raw materials in this example.

[0078] Example 8 Raw material components: Component A (parts by weight): 39 parts castor oil, 26 parts lignin-modified polyether polyol, 10 parts PLA-modified polyol, 4.9 parts distilled water, 3.1 parts cyclopentane, 0.62 parts DBTDL, 0.38 parts TEDA, 8.2 parts APP, 3.1 parts modified starch-based flame retardant, 1.25 parts CTAB, 1.55 parts KH-550, 1.05 parts L-580, 0.055 parts bromothymol blue, 0.85 parts chitosan, 0.26 parts lanthanum nitrate, and 0.16 parts nano-cerium oxide.

[0079] Component B (parts by weight): MDI-50 113 parts, HDI 14 parts.

[0080] The mass ratio of component A to component B is 1:1.27.

[0081] Preparation method: Same as in Example 1, but the parameters are adjusted accordingly based on the amount of raw materials in this example.

[0082] Comparative Example 1 Raw material components: Component A (parts by weight): 40 parts castor oil, 25 parts lignin-modified polyether polyol, 10 parts PLA-modified polyol, 5 parts distilled water, 3 parts cyclopentane, 0.6 parts DBTDL, 0.4 parts TEDA, 8 parts APP, 3 parts modified starch-based flame retardant, 1.2 parts CTAB, 1.5 parts KH-550, 1.1 parts L-580, 0.05 parts bromothymol blue, 0.8 parts chitosan, 0 parts lanthanum nitrate, and 0 parts nano-cerium oxide.

[0083] Component B (parts by weight): MDI-50 115 parts, HDI 12 parts.

[0084] The mass ratio of component A to component B is 1:1.28.

[0085] Preparation method: basically the same as in Example 1, but step S1 is omitted, and the components are directly mixed in step S2.

[0086] Comparative Example 2 Raw material components: Component A (parts by weight): 40 parts castor oil, 25 parts lignin-modified polyether polyol, 10 parts PLA-modified polyol, 5 parts distilled water, 3 parts cyclopentane, 0.6 parts DBTDL, 0.4 parts TEDA, 0 parts APP, 3 parts modified starch-based flame retardant, 1.2 parts CTAB, 1.5 parts KH-550, 1.1 parts L-580, 0.05 parts bromothymol blue, 0.8 parts chitosan, 0.25 parts lanthanum nitrate, and 0.15 parts nano-cerium oxide.

[0087] Component B (parts by weight): MDI-50 115 parts, HDI 12 parts.

[0088] The mass ratio of component A to component B is 1:1.28.

[0089] Preparation method: Basically the same as in Example 1.

[0090] Comparative Example 3 Raw material components: Component A (parts by weight): 40 parts castor oil, 25 parts lignin-modified polyether polyol, 10 parts PLA-modified polyol, 5 parts distilled water, 3 parts cyclopentane, 0.6 parts DBTDL, 0.4 parts TEDA, 8 parts APP, 3 parts modified starch-based flame retardant, 1.2 parts CTAB, 0 parts KH-550, 1.1 parts L-580, 0.05 parts bromothymol blue, 0.8 parts chitosan, 0.25 parts lanthanum nitrate, and 0.15 parts nano-cerium oxide.

[0091] Component B (parts by weight): MDI-50 115 parts, HDI 12 parts.

[0092] The mass ratio of component A to component B is 1:1.28.

[0093] Preparation method: basically the same as in Example 1.

[0094] Samples of bio-based polyurethane foams prepared in Examples 1-8 and Comparative Examples 1-3 were taken. The mass of foam per unit volume of each sample was measured according to GB / T 6343-2009. The distribution of pores in each foam sample was determined using scanning electron microscopy. Porosity and specific surface area were measured by mercury intrusion porosimetry. The compressive strength and deformation recovery rate of each sample were determined according to GB / T 6669-2008. The tensile strength of each foam sample was determined according to GB-T 6344-2008. The oxygen index of each foam sample was determined according to GBT 2406.2-2009. The soil degradation rate of each foam sample was measured according to ISO 17556:2019 "Plastics—Measurement of the final aerobic biodegradability of plastic materials in soil by measuring the oxygen demand or carbon dioxide content in a sound absorber". The adsorption ratio of each foam sample was determined according to ASTM F726-17(2024) "Standard test method for adsorption performance of adsorbents for crude oil and related spills". Thermogravimetric analysis was performed according to ISO... The thermal decomposition temperature of each foam sample was determined according to 11358-1:2014 "Plastics - Thermogravimetric analysis (TG) of polymers - Part 1: General principles". Performance test results are shown in Table 1.

[0095] Table 1: Performance Test Results ; ; As shown in Table 1, the bio-based polyurethane foam of the present invention can achieve high flame retardancy, oxygen index >30%, high adsorption rate, adsorption rate of diesel oil greater than 25 times, and high thermal stability, with an initial decomposition temperature T5% greater than 278°C, which improves environmental friendliness. The soil degradation rate is greater than 80% after 180 days. Its bio-based polyol composition and rare earth modified additives are well designed, and the components synergistically enhance each other, resulting in excellent comprehensive performance.

[0096] Please see Figure 2 and Figure 3 As shown, Figure 2 This is a SEM image of the bio-based polyurethane foam from Example 1 of the present invention; Figure 3 This is the SEME diagram of the bio-based polyurethane foam of Comparative Example 3 of the present invention.

[0097] from Figure 2 and Figure 3 As can be seen, the bio-based polyurethane foam of Example 1 of the present invention has a narrower pore size distribution range, more regular pore shape, smooth and complete pore walls, and a continuous and robust pore wall structure compared to Comparative Example 1. The pores are mostly independent closed-cell or interconnected open-cell structures, arranged in an orderly manner.

[0098] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A high-temperature resistant, flame-retardant bio-based polyurethane foam, characterized in that, The bio-based polyurethane foam is made by mixing component A and component B in a mass ratio of 1:1.2 to 1.35; Component A consists of the following raw materials in parts by weight: The composition comprises 75-85 parts of a bio-based polyol composition, 8-10 parts of a foaming agent, 0.8-1.2 parts of a catalyst, 10-12 parts of a flame retardant, 1.0-1.5 parts of an antistatic agent, 2.5-3.0 parts of a functional additive, 0.03-0.08 parts of a visualization additive, 0.5-1.0 parts of an antibacterial agent, and 0.3-0.5 parts of a rare earth modifying additive. The bio-based polyol composition includes castor oil, lignin-modified polyether polyol, and polylactic acid-modified polyol. The rare earth modifying additive includes lanthanum nitrate and nano-cerium oxide. Component B is prepared by mixing 110-120 parts by weight of diphenylmethane diisocyanate (MDI-50) and 10-15 parts by weight of hexamethylene diisocyanate (HDI).

2. The high-temperature resistant, flame-retardant bio-based polyurethane foam according to claim 1, characterized in that, The mass ratio of the castor oil, the lignin-modified polyether polyol, and the polylactic acid-modified polyol is 40:25:

10.

3. The high-temperature resistant, flame-retardant bio-based polyurethane foam according to claim 1, characterized in that, The mass ratio of lanthanum nitrate to nano-cerium oxide is 0.25:0.

15.

4. The high-temperature resistant, flame-retardant bio-based polyurethane foam according to claim 1, characterized in that, The foaming agent comprises distilled water and cyclopentane in a mass ratio of 5:

3.

5. The high-temperature resistant, flame-retardant bio-based polyurethane foam according to claim 1, characterized in that, The catalyst comprises dibutyltin dilaurate and triethylenediamine in a mass ratio of 0.6:0.

4.

6. The high-temperature resistant, flame-retardant bio-based polyurethane foam according to claim 1, characterized in that, The flame retardant comprises ammonium polyphosphate and modified starch-based flame retardant in a mass ratio of 8:

3.

7. The high-temperature resistant, flame-retardant bio-based polyurethane foam according to claim 1, characterized in that, The antistatic agent is hexadecyltrimethylammonium bromide, and the visualization aid is bromothymol blue.

8. The high-temperature resistant, flame-retardant bio-based polyurethane foam according to claim 1, characterized in that, The functional additives include silane coupling agent KH-550 and polysiloxane foam stabilizer L-580 in a mass ratio of 1.5:1.1, and the antibacterial agent is chitosan with a degree of deacetylation greater than or equal to 90%.

9. The high-temperature resistant, flame-retardant bio-based polyurethane foam according to claim 1, characterized in that, The bio-based polyurethane foam has an oxygen index greater than or equal to 30%, a thermal decomposition temperature greater than or equal to 240℃, a soil degradation rate greater than or equal to 80%, and an adsorption ratio greater than or equal to 25 times.

10. A method for preparing the high-temperature resistant, flame-retardant bio-based polyurethane foam according to any one of claims 1-9, characterized in that, include: Step S1: Lanthanum nitrate and distilled water are used to prepare a lanthanum nitrate pre-dispersion, and nano-cerium oxide and castor oil are used to prepare a nano-cerium oxide pre-dispersion. Step S2: Castor oil, lignin-modified polyether polyol and polylactic acid-modified polyol are added to the vacuum stirred tank in sequence. After stirring evenly, the lanthanum nitrate pre-dispersion and the nano-cerium oxide pre-dispersion are injected into the vacuum stirred tank at an injection rate of 5 mL / min. Step S3: After stirring evenly, add distilled water and cyclopentane to the vacuum stirred vessel in sequence, heat to 40°C and stir evenly. Step S4: After cooling to 25°C, add catalyst, flame retardant, antistatic agent, functional additive, bromothymol blue and chitosan in sequence, stir evenly and degas to obtain component A; Step S5: Inject MDI-50 and HDI into a vacuum stirred tank and stir until homogeneous to obtain component B; Step S6: Add component A and component B to the high-pressure foaming spray gun in proportion, and obtain bio-based polyurethane foam after foaming and curing.

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