High-dispersion halogen-free flame retardant polyether polyol composite material and preparation method thereof

Abstract

The invention relates to the field of artificial leather, and discloses a high-dispersion halogen-free flame retardant polyether polyol composite material and a preparation method thereof, and the high-dispersion halogen-free flame retardant polyether polyol composite material comprises the following components by mass: 60-75 parts of a polyether polyol matrix; 20 to 30 parts of a core-shell synergistic flame retardant; 3 to 5 parts of a hyperbranched polysiloxane dispersant; 2-5 parts of a nano zinc borate synergist; 0.5 to 1 part of an anti-dripping agent; the preparation method comprises the following steps: preparing a phosphorus-nitrogen core-shell flame retardant; premixing with polyether polyol, and performing dynamic condensation to form a bonding interface; carrying out ultrasonic-shearing synergistic dispersion on the nano material; and finally, carrying out underwater pelletizing to obtain the high-dispersion halogen-free composite material. According to the invention, through cooperation of core-shell flame-retardant structure design and a dynamic process, and combination of hyperbranched dispersant multi-point anchoring and ultrasonic-shear energy field dispersion technologies, efficient dispersion of a flame retardant and a nano material is realized; the interfacial condensation reaction is accurately controlled through a low-oxygen environment, and the flame retardant efficiency and thermal stability of the material are improved.

Description

Technical Field

[0001] The present invention relates to the field of artificial leather, in particular to a highly dispersed halogen-free flame retardant polyether polyol composite material and a preparation method thereof. Background Art

[0002] To enhance flame retardancy, traditional artificial leather typically uses a physical blend of flame retardants and base resins. However, the polarity differences between the flame retardant and the resin lead to uneven dispersion, which can easily lead to particle aggregation on the surface. This not only reduces flame retardancy but also causes the leather surface to feel hard and have a rough texture. For example, while high levels of aluminum hydroxide can improve flame retardancy, they significantly reduce the coating's flexibility, making it difficult to meet the dual demands of tactile feel and functionality for high-end furniture and automotive interior leather.

[0003] To impart antimicrobial and antistatic properties to artificial leather, the introduction of nanoscale functional particles is often necessary. However, existing dispersion technologies struggle to achieve long-term, stable dispersion of nanoparticles within a resin matrix. Conventional dispersants, due to their simple molecular structure, are unable to effectively inhibit particle migration and aggregation during processing, leading to localized color variations and uneven gloss on the leather surface. Furthermore, highly filled systems suffer from poor melt flow, leading to significant torque fluctuations during extrusion, and resulting in defects such as uneven thickness and a tangerine peel finish on the finished leather.

[0004] The interfacial bonding strength between artificial leather coatings and the base fabric directly impacts their peel resistance and service life. In traditional processes, resin coatings are often exposed to the open air during curing. Fluctuations in temperature and humidity can easily lead to incomplete condensation of the coating or oxidative degradation of the base fabric fibers, resulting in insufficient interfacial adhesion.

[0005] Therefore, the present invention provides a highly dispersed halogen-free flame retardant polyether polyol composite material and a preparation method thereof to address the deficiencies of the prior art. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides a highly dispersed halogen-free flame retardant polyether polyol composite material and a preparation method thereof, which solves the problems of mechanical property degradation, poor processing stability and insufficient durability of the coating-base fabric interface caused by uneven dispersion of flame retardants in traditional artificial leather.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: A highly dispersed halogen-free flame retardant polyether polyol composite material comprises the following components in parts by weight: Polyether polyol matrix: 60-75 parts; Core-shell synergistic flame retardant: 20-30 parts; Hyperbranched polysiloxane dispersant: 3-5 parts; Nano zinc borate synergist: 2-5 parts; Anti-dripping agent: 0.5-1 part.

[0008] A polyether polyol matrix having a hydroxyl value of 42-48 mgKOH / g and a molecular weight of 3000-5000; Matching hydroxyl value with molecular weight: When the hydroxyl value is too low (<42mgKOH / g), the condensation reaction activity with the flame retardant shell is insufficient; when the hydroxyl value is too high (>48mgKOH / g), the system viscosity is too high, making processing difficult; the molecular weight range of 3000-5000 takes into account both fluidity and mechanical properties; Core-shell synergistic flame retardant, the core layer is phosphorus-nitrogen synergistic nanoparticles, the shell layer is vinyl siloxane-polyether block copolymer, the molar ratio of siloxane:polyether is 1:2-1:3.

[0009] Core layer phosphorus-nitrogen synergy: DOPO provides gas-phase flame retardancy, while MPP suppresses smoke by forming carbon in the condensed phase, and the two work together to improve flame retardancy efficiency; Shell block design: The siloxane segment provides thermal stability, and the polyether segment condenses with the matrix hydroxyl group to form a Si-OC bond, which increases the interfacial bonding strength by more than 30% compared to physical adsorption; Hyperbranched polysiloxane dispersant, using the third generation hyperbranched structure, with a terminal amino group to epoxy group molar ratio of 1:1; Topological entanglement effect: The third generation of hyperbranched structures has a high branching degree of ≥80%, and the nanoparticles are fixed by molecular chain entanglement; Dual reactivity: amino groups react with isocyanate groups of polyether prepolymers, and epoxy groups bond with hydroxyl groups on the surface of flame retardants, forming a dual "anchoring-entanglement" effect, which improves dispersion stability; Nano zinc borate synergist, particle size 50-100nm, surface modified with organosiloxane.

[0010] Nanosize effect: Zinc borate with a particle size of 50-100nm has a large specific surface area, and its smoke suppression efficiency is significantly improved compared to the micron size; surface modification to prevent agglomeration: organic silicones, such as γ-aminopropyltriethoxysilane, and the modified layer prevent nanoparticles from competing with flame retardants for adsorption of dispersants.

[0011] Anti-dripping agent, polytetrafluoroethylene powder, particle size 1-2μm; Droplet suppression network: PTFE forms a fibrous network at processing temperature to prevent the molten material from dripping, and the anti-drip efficiency is improved compared to when it is not added.

[0012] Preferably, the hydroxyl value of the polyether polyol matrix is 42-48 mgKOH / g and the molecular weight is 3000-5000; the core layer of the core-shell synergistic flame retardant is phosphorus-nitrogen synergistic nanoparticles, and the shell layer is vinylsiloxane-polyether block copolymer, wherein the molar ratio of the siloxane segment to the polyether segment is 1:2-1:3.

[0013] Preferably, the hyperbranched polysiloxane dispersant is a third generation hyperbranched structure, the terminal functional groups are amino and epoxy groups, and the molar ratio of amino to epoxy groups is 1:1.

[0014] Preferably, the nano zinc borate synergist has a particle size of 50-100 nm and its surface is modified with organosiloxane; the anti-dripping agent is polytetrafluoroethylene powder with a particle size of 1-2 μm.

[0015] The present invention also provides a method for preparing a highly dispersed halogen-free flame retardant polyether polyol composite material, comprising the following steps: S1, dissolving DOPO flame retardant and melamine polyphosphate in a solvent, heating and reacting, separating and drying to obtain phosphorus-nitrogen synergistic core layer particles; The core layer particles are dispersed in a vinyl siloxane-polyether block copolymer solution, an initiator is added, and the mixture reacts under an inert atmosphere to form a core-shell structure flame retardant; S2, premixing the polyether polyol matrix, the core-shell synergistic flame retardant, and the hyperbranched polysiloxane dispersant to form a homogeneous slurry to obtain a premix; S3, feeding the premix into a twin-screw reaction extruder, and dynamically adjusting the temperature and screw speed to cause a condensation reaction between the shell siloxane and the polyether polyol to form a chemically bonded interface; S4, adding nano zinc borate synergist and anti-dripping agent to the molten material, and simultaneously applying ultrasonic cavitation and high-speed shear force to achieve nano-scale dispersion; S5. The dispersed melt is pelletized through an underwater pelletizing process, and the composite material particles are obtained after drying.

[0016] Preferably, in step S1, DOPO flame retardant and melamine polyphosphate are dissolved in ethanol solvent in a mass ratio of 1:1.1-1:1.3, the pH is adjusted to 4.0-5.0 at a reaction temperature of 78-82°C, the reaction is carried out for 3.5-4.5 hours, the precipitate is separated by centrifugation at a centrifugal speed of 8000-10000 rpm, and the precipitate is vacuum dried at 60°C for 12 hours to obtain phosphorus-nitrogen synergistic core layer particles; the core layer particles are dispersed in a vinyl siloxane-polyether block copolymer solution with a molar ratio of siloxane to polyether chain segments of 1:2-1:3, 0.4-0.6wt% of azobisisobutyronitrile as a free radical initiator is added, the reaction is carried out at 68-72°C under nitrogen protection for 5.5-6.5 hours, the centrifugal speed is 6000-8000 rpm, and the product is vacuum dried at 50°C for 8 hours to obtain a core-shell flame retardant with a shell thickness of 10-20 nm.

[0017] Controllable synthesis of the core layer: Under acidic pH = 4.0-5.0, DOPO and MPP self-assemble through hydrogen bonding to form uniform nanoparticles; In-situ polymerization of the shell: AIBN initiates the free radical polymerization of vinylsiloxane, and the block copolymer is bonded to the core layer through a condensation reaction. The shell thickness of 10-20nm can be precisely controlled.

[0018] Preferably, in step S2, the polyether polyol matrix, the core-shell synergistic flame retardant, and the hyperbranched polysiloxane dispersant are added to a premixer at a premixing speed of 480-520 rpm, for 9-11 min, and at a temperature of 22-28° C. to form a homogeneous slurry to obtain a premix.

[0019] Shear force matching: At a rotation speed of 480-520 rpm, the hyperbranched dispersant induces orientation through shear, preliminarily dispersing the flame retardant and preventing the prepolymer from degrading.

[0020] Preferably, in step S3, the premix is put into a twin-screw reaction extruder with a screw speed of 200-300 rpm and a barrel temperature according to the formula T=120+0.2N, where T is the temperature of the twin-screw reaction extruder and N is the screw speed, corresponding to a temperature of 160-180°C, a residence time of 5-8 min, and an oxygen concentration of 40-50 ppm, so that the shell siloxane and the polyether polyol hydroxyl group condense to form a chemically bonded interface.

[0021] Temperature-speed coupling: The formula T = 120 + 0.2N ensures that the reaction temperature increases linearly with the screw speed, avoiding local overheating that causes shell decomposition; Condensation reaction control: Low oxygen environment inhibits oxidative cross-linking of siloxane segments, and the condensation reaction selectivity is ≥95%.

[0022] Preferably, in step S4, nano zinc borate synergist and anti-dripping agent are added to the molten material, and ultrasonic waves with a frequency of 40 kHz, a power of 500 W, and a shear rate of 5000-8000 s are simultaneously applied. -1 , the ultrasonic action time accounts for 60-70%, the total dispersion time is 15-20min, and the treated melt is obtained.

[0023] Preferably, in step S5, the melt is pelletized by an underwater pelletizer, the pelletizing water temperature is 10-15° C., the pelletizing speed is 200-300 rpm, the particle size is 2-3 mm, vacuum dried at 50° C. for 4 h, the moisture content is 0.05-0.1%, and the pellets are sealed and packaged.

[0024] Low temperature anti-oxidation: 10-15℃ water temperature quickly cools the melt to prevent the PTFE network from breaking due to high temperature oxidation; Precise moisture control: moisture content is ≤0.1% after vacuum drying, avoiding degradation of mechanical properties caused by hydrolysis of polyether polyols.

[0025] The present invention provides a highly dispersed halogen-free flame retardant polyether polyol composite material and a preparation method thereof. Beneficial effects: 1. This invention significantly improves flame retardancy and smoke suppression performance by constructing a phosphorus-nitrogen / siloxane gradient flame retardant system and combining it with real-time dynamic matching of process parameters. Compared to the weak interfacial bonding issues of traditional physically blended flame retardant systems, this solution addresses the industry pain points of uneven flame retardant dispersion and poor thermal stability through core-shell structural design and process synergy, achieving simultaneous optimization of flame retardancy and material mechanical properties.

[0026] 2. This invention, based on the topological design of hyperbranched polymers and precise control of functional groups, achieves efficient dispersion and interface strengthening of flame retardants and nanoparticles. Conventional dispersants in the prior art struggle to suppress particle aggregation in highly filled systems due to insufficient molecular chain flexibility. This approach, however, leverages the multi-point anchoring effect of the hyperbranched network to significantly improve the material's mechanical property retention, overcoming the technical bottleneck of brittleness in highly filled composite materials.

[0027] 3. By coupling ultrasonic cavitation with a shear field, this invention achieves efficient deagglomeration and uniform dispersion of nanomaterials. Compared to the localized stress concentration defects caused by mechanical shear dispersion alone, this technical solution significantly improves the interfacial compatibility of nanoparticles while maintaining processing efficiency, resolving the core issue of easy failure of nano-reinforced phases in traditional processes.

[0028] 4. By precisely controlling the oxygen concentration in the processing environment, this invention achieves highly selective chemical bonding between the flame retardant shell and the substrate. This low-oxygen process fundamentally suppresses the interfacial embrittlement caused by oxidative side reactions in existing technologies, imparting the material with excellent thermal stability and long-term aging resistance, providing an innovative approach for the preparation of high-reliability composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] See also Figure 1 : Example 1: Raw material ratio (mass fraction): Polyether polyol matrix: 70 parts; Core-shell synergistic flame retardant: 25 parts; Hyperbranched polysiloxane dispersant: 4 parts; Nano zinc borate synergist: 3 parts; Anti-dripping agent: 0.8 parts.

[0032] The preparation steps are as follows: 1. Preparation of core-shell flame retardant: DOPO and melamine polyphosphate were dissolved in ethanol solvent at a mass ratio of 1:1.2 and a solid-liquid ratio of 1:10 g / mL. The mixture was reacted at 80°C for 4 hours. The pH was adjusted to 4.5, and the precipitate was separated by centrifugation at a speed of 9000 rpm. The precipitate was vacuum-dried at 60°C for 12 hours to obtain phosphorus-nitrogen synergistic core layer particles with a particle size of ≤200 nm.

[0033] The core layer particles were dispersed in a vinyl siloxane-polyether block copolymer solution with a molar ratio of siloxane to polyether segments of 1:2.5. 0.5% azobisisobutyronitrile initiator was added. The mixture was reacted at 70°C for 6 hours under nitrogen protection and a centrifugal speed of 7000 rpm. The product was vacuum dried at 50°C for 8 hours to obtain a core-shell flame retardant with a shell thickness of 15 nm.

[0034] 2. Preparation of premix: The polyether polyol matrix, core-shell synergistic flame retardant, and hyperbranched polysiloxane dispersant were added to a high-speed premixer at a premixing speed of 500 rpm for 10 minutes at a temperature of 25° C. to form a homogeneous slurry.

[0035] 3. Dynamic in-situ grafting composite: The premix was fed into a twin-screw reaction extruder with a screw speed of 250 rpm, a barrel temperature according to the formula T=120+0.2×250=170°C, a residence time of 6 minutes, an oxygen concentration of 45 ppm, and the shell siloxane and the polyether polyol hydroxyl groups condensed to form a chemically bonded interface.

[0036] 4. Ultrasonic-shear coupling dispersion: Add nano zinc borate synergist and anti-dripping agent to the molten material, and simultaneously apply ultrasonic waves with a frequency of 40kHz, a power of 500W, and a shear rate of 6500s -1 , the ultrasonic action time accounts for 65%, and the total dispersion time is 18 minutes.

[0037] 5. Continuous granulation: The melt was pelletized by an underwater pelletizer, the pelletizing water temperature was 12° C., the pelletizing speed was 250 rpm, the particle size was 2.5 mm, and the pellets were vacuum dried at 50° C. for 4 hours, with a moisture content of 0.08%, and then sealed and packaged.

[0038] Example 2: Raw material ratio (mass fraction): Polyether polyol matrix: 60 parts; Core-shell synergistic flame retardant: 20 parts; Hyperbranched polysiloxane dispersant: 3 parts; Nano zinc borate synergist: 2 parts; Anti-dripping agent: 0.5 parts.

[0039] The preparation steps are as follows: 1. Preparation of core-shell flame retardant: DOPO and melamine polyphosphate were dissolved in ethanol solvent at a mass ratio of 1:1.1, with a solid-liquid ratio of 1:10 g / mL. The mixture was reacted at 78°C for 3.5 hours, the pH was adjusted to 4.0, the centrifugation speed was 8000 rpm, and the precipitate was vacuum-dried at 60°C for 12 hours to obtain core layer particles with a particle size of ≤200 nm.

[0040] The core layer particles were dispersed in a vinylsiloxane-polyether block copolymer solution with a molar ratio of siloxane to polyether segments of 1:2. 0.4% azobisisobutyronitrile initiator was added. The reaction was carried out at 68°C under nitrogen protection for 5.5 hours, with a centrifugal speed of 6000 rpm. The product was vacuum dried at 50°C for 8 hours, and the shell thickness was 10 nm.

[0041] 2. Preparation of premix: The premixing speed was 480 rpm, the time was 9 minutes, and the temperature was 22° C. to form a homogeneous slurry.

[0042] 3. Dynamic in-situ grafting composite: The twin-screw extruder had a screw speed of 200 rpm, a barrel temperature of 160°C, a residence time of 5 minutes, and an oxygen concentration of 40 ppm.

[0043] 4. Ultrasonic-shear coupling dispersion: Ultrasonic frequency 40kHz, power 450W, shear rate 5000s -1 , the ultrasonic action time accounts for 60%, and the total dispersion time is 15 minutes.

[0044] 5. Continuous granulation: The pelletizing water temperature was 10°C, the pelletizing speed was 200 rpm, the particle size was 2 mm, and the moisture content was 0.05%.

[0045] Example 3: Raw material ratio (mass fraction): Polyether polyol matrix: 75 parts; Core-shell synergistic flame retardant: 30 parts; Hyperbranched polysiloxane dispersant: 5 parts; Nano zinc borate synergist: 5 parts; Anti-drip agent: 1 part.

[0046] The preparation steps are as follows: 1. Preparation of core-shell flame retardant: DOPO and melamine polyphosphate were dissolved in ethanol solvent at a mass ratio of 1:1.3 and a solid-liquid ratio of 1:10 g / mL. The mixture was reacted at 82°C for 4.5 hours, the pH was adjusted to 5.0, the centrifugal speed was 10,000 rpm, and the precipitate was vacuum-dried at 60°C for 12 hours to obtain core layer particles.

[0047] The core layer particles were dispersed in a vinylsiloxane-polyether block copolymer solution with a molar ratio of siloxane to polyether segments of 1:3. 0.6% azobisisobutyronitrile initiator was added. The reaction was carried out at 72°C under nitrogen protection for 6.5 hours, with a centrifugal speed of 8000 rpm. The product was vacuum dried at 50°C for 8 hours, and the shell thickness was 20 nm.

[0048] 2. Preparation of premix: The premixing speed was 520 rpm, the time was 11 minutes, and the temperature was 28°C.

[0049] 3. Dynamic in-situ grafting composite: The twin-screw extruder had a screw speed of 300 rpm, a barrel temperature of 180°C, a residence time of 8 minutes, and an oxygen concentration of 50 ppm.

[0050] 4. Ultrasonic-shear coupling dispersion: Ultrasonic frequency 40kHz, power 550W, shear rate 8000s -1 , the ultrasonic action time accounts for 70%, and the total dispersion time is 20 minutes.

[0051] 5. Continuous granulation: The pelletizing water temperature was 15°C, the pelletizing speed was 300 rpm, the pellet size was 3 mm, and the moisture content was 0.1%.

[0052] Comparative Example 1 Compared with Example 1, the difference is that the core-shell synergistic flame retardant is replaced by a physical mixture of DOPO and MPP with a mass ratio of 1:1.2, and the core-shell structure is not constructed. The rest are the same.

[0053] Comparative Example 2 Compared with Example 1, the difference is that the hyperbranched polysiloxane dispersant is replaced by the common silane coupling agent KH-550, and the rest are the same.

[0054] Comparative Example 3 Compared with Example 1, the difference is that the nano zinc borate synergist is not surface modified, and the rest are the same.

[0055] Comparative Example 4 Compared with Example 1, the difference is that the temperature-rotation speed coupling formula is cancelled in the dynamic in-situ grafting step, and the rest are the same.

[0056] Comparative Example 5 Compared with Example 1, the difference is that the shear force is only applied for 6500s in the ultrasound-shear dispersion step. -1 And cancel the ultrasound, the rest are the same.

[0057] Comparative Example 6 Compared with Example 2, the difference is that the hydroxyl value of the polyether polyol matrix is 38 mgKOH / g, which exceeds the scope of Claim 2, and the rest are the same.

[0058] Comparative Example 7 Compared with Example 2, the difference is that the molar ratio of shell siloxane to polyether segment is changed to 1:1, and the rest are the same.

[0059] Comparative Example 8 Compared with Example 3, the difference is that the hyperbranched polysiloxane dispersant is replaced by the second-generation hyperbranched structure, and the rest are the same.

[0060] Comparative Example 9 Compared with Example 3, the difference is that the oxygen concentration in the dynamic in-situ grafting step is 200 ppm, and the rest are the same.

[0061] Comparative Example 10 Compared with Example 3, the difference is that the anti-dripping agent is untreated PTFE powder, and the rest are the same.

[0062] Test Example 1: Flame retardant and smoke suppression performance experiment Experimental purpose: to verify the effects of core-shell flame retardant design, dynamic process parameter coupling and shell siloxane ratio on the flame retardant and smoke suppression performance of the material.

[0063] The experimental steps are as follows: Sample preparation: Composite material strips were prepared according to the formulations and processes of Example 1, Comparative Example 1, Comparative Example 4, and Comparative Example 7, with dimensions of 100×10×3 mm.

[0064] Limiting Oxygen Index (LOI) test: According to GB / T-2406 standard, the minimum oxygen concentration required for vertical combustion of the test specimen is measured in an oxygen index meter.

[0065] Test conditions: gas flow rate 40±10 mm / s, ignition time 30 s, repeat 5 times for each group and take the average value.

[0066] Smoke density (D4) test: Use smoke density chamber (ISO-5659-2), heat radiation flux 50kW / m 2 , test the opacity of smoke after the material burns (D4 value).

[0067] Data collection time: 0-600s, record the maximum smoke density value.

[0068] Vertical burning rating (UL94): According to the UL94 standard, the sample was ignited twice for 10 seconds, and the burning time and the ignition of cotton by the dripping matter were recorded.

[0069] Rating standards: V-0 (extinguishing time ≤ 10s, no ignition), V-1 (≤ 30s), V-2 (≤ 30s but ignites cotton).

[0070] The experimental data are shown in Table 1: Table 1: Comparison of flame retardant and smoke suppression performance Test Group LOI (%) Smoke density D4 UL94 rating Example 1 29.4 163 V-0 Comparative Example 1 23.8 326 V-2 Comparative Example 4 26.1 218 V-1 Comparative Example 7 27.5 195 V-1 Experimental summary: The key role of core-shell flame retardants: The phosphorus-nitrogen synergistic core layer of the core-shell flame retardant in Example 1 significantly increases the LOI to 29.4% through the synergistic effect of gas-phase flame retardancy (DOPO releases PO radicals) and condensed-phase carbonization (MPP promotes carbon layer formation). In contrast, the LOI in Comparative Example 1 is only 23.8% due to the lack of interfacial synergy in the physically mixed flame retardant. The core-shell structure also suppresses smoke generation through the thermal stability of the shell siloxane (siloxane segments), resulting in a 50% reduction in smoke density D4 compared to Comparative Example 1.

[0071] Necessity of dynamic process parameters: Comparative Example 4 used a fixed temperature-rotation speed (170°C / 250 rpm), resulting in incomplete condensation reaction between the shell siloxane and the polyether matrix (the interfacial bonding rate decreased by approximately 40%), deteriorating the flame retardant-matrix compatibility, reducing the LOI to 26.1%, and increasing the smoke density to 218. Example 1 dynamically adjusted the temperature using the formula T = 120 + 0.2N to ensure reaction uniformity and an interfacial bonding rate of ≥ 95%.

[0072] Mechanism for regulating the siloxane ratio in the shell: The excessively high siloxane ratio (1:1) in Comparative Example 7 resulted in increased shell rigidity, decreased flame retardant dispersibility, and susceptibility to cracking in the char layer during combustion (SEM observation of crack density +35%), with smoke density D4 rising to 195. The siloxane:polyether ratio of 1:2.5 in Example 1 balanced shell flexibility and thermal stability, resulting in a continuous and dense char layer and optimal smoke suppression efficiency.

[0073] Test Example 2: Dispersibility and Mechanical Properties Experiment Experimental Purpose: To verify the dynamic volume expansion effect of hyperbranched dispersant, the surface modification of nano zinc borate and the influence of anti-dripping agent particle size on the dispersion uniformity and mechanical properties of the material.

[0074] The experimental steps are as follows: Sample preparation: Standard test specimens were prepared according to the formulations and processes of Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 8, and Comparative Example 10, including tensile specimens: ASTM-D638-Type-I; and impact specimens: ASTM-D256.

[0075] Laser particle size analysis (D90): A composite material powder sample was taken, dispersed in deionized water, and ultrasonically treated for 5 minutes. The particle size of the dispersed particles was measured using a laser particle size analyzer (D90 indicates that the particle size of 90% of the particles is smaller than this value).

[0076] Tensile strength test: According to ASTM-D638, the specimen was stretched at a rate of 50 mm / min on a universal testing machine until it broke, the maximum tensile strength was recorded, and the retention rate (relative to the pure matrix) was calculated.

[0077] Impact strength test: According to ASTM-D256 standard, the impact strength of the notched specimen was tested using an Izod impact tester (unit: kJ / m 2 ).

[0078] The experimental data are shown in Table 2: Table 2: Comparison of dispersibility and mechanical properties Test Group D90(μm) Tensile strength retention rate (%) <![CDATA[Impact strength (kJ / m 2 )]]> Example 1 0.53 87.6 12.4 Comparative Example 2 1.82 71.3 8.9 Comparative Example 3 1.35 78.4 10.1 Comparative Example 8 2.14 65.8 7.3 Comparative Example 10 0.98 82.7 9.6 Experimental summary: Dynamic Compatibilization Effect of Hyperbranched Dispersants: The third-generation hyperbranched polysiloxane dispersant in Example 1 achieves bidirectional anchoring of the core-shell flame retardant and nano-zinc borate through a 1:1 functional group balance of amino and epoxy groups. Its highly branched topological structure (branching degree ≥ 80%) inhibits particle migration through molecular chain entanglement, with a D90 value as low as 0.53 μm. In contrast, the D90 values of Comparative Example 2 (conventional silane coupling agent) and Comparative Example 8 (second-generation dispersant) rise to 1.82 μm and 2.14 μm, respectively, due to the lack of topological entanglement and functional group synergy, and the tensile strength retention rate drops to 71.3% and 65.8%.

[0079] Anti-agglomeration mechanism of surface modification: In Comparative Example 3, the unmodified nano zinc borate, due to the competition between the surface hydroxyl groups and the flame retardant for the adsorption of the dispersant, resulted in local agglomeration (D90 = 1.35 μm), and the tensile strength retention rate dropped to 78.4%. In Example 1, the surface of zinc borate was modified with γ-aminopropyltriethoxysilane. Through covalent bonding between the siloxane and the epoxy groups of the dispersant, the dispersion path was directional and regulated, and the impact strength was increased to 12.4 kJ / m 2 , which is 22.8% higher than that of Comparative Example 3.

[0080] Effect of anti-drip agent particle size on the dispersion network: The untreated PTFE powder (5 μm) in Comparative Example 10 was too large to form a uniform fibrous network in the matrix, and the impact strength was only 9.6 kJ / m 2 Example 1 uses 1-2 μm PTFE powder to form a dense anti-drip network under the ultrasonic-shear energy field while avoiding interference with the dispersion of nanoparticles (D90=0.53 μm), and the tensile strength retention rate is as high as 87.6%.

[0081] Test Example 3: Process Stability and Processing Performance Experiment Experimental Purpose: To verify the effects of matrix hydroxyl value / molecular weight, dynamic process oxygen concentration control and ultrasonic-shear energy field on processing fluidity and thermal stability.

[0082] The experimental steps are as follows: Sample preparation: Composite material particles were prepared according to the formula and process of Example 2, Comparative Example 6, Comparative Example 9 and Comparative Example 5.

[0083] Melt flow rate (MFR) test: According to GB / T-3682 standard, the test was carried out in a melt indexer (conditions: 190°C / 2.16 kg), and the weight of the material extruded within 10 minutes was recorded (unit: g / 10 minutes).

[0084] Extruder torque monitoring: The torque value (unit: N·m) was monitored in real time in the twin-screw extruder, and the process fluctuation coefficient (standard deviation / mean × 100%) was calculated.

[0085] Heat Deflection Temperature (HDT) Test: According to ISO-75 standard, a load of 0.45 MPa is applied in the thermal deformation tester, and the temperature at which the material deformation reaches 0.2 mm is tested at a heating rate of 120°C / h.

[0086] The experimental data are shown in Table 3: Table 3: Comparison of process stability and processing performance Test Group MFR (g / 10min) Torque fluctuation coefficient (%) HDT(℃) Example 2 5.2 8.3 142.5 Comparative Example 6 3.8 21.6 127 Comparative Example 9 4.6 14.7 135 Comparative Example 5 6.9 18.9 129.3 Experimental summary: Processing compatibility between matrix hydroxyl value and molecular weight: In Example 2, the polyether polyol matrix, with a hydroxyl value of 42 mgKOH / g and a molecular weight of 3000, ensured compatibility with the polyether segments in the core-shell flame retardant shell, resulting in a stable melt flow rate of 5.2 g / 10 min. In contrast, in Comparative Example 6, due to its low hydroxyl value (38 mgKOH / g), the condensation reaction between the matrix and the flame retardant shell was insufficient, resulting in a melt flow rate drop to 3.8 g / 10 min and a torque fluctuation coefficient of 21.6% (a 160% increase compared to Example 2), indicating severe phase separation during processing.

[0087] Oxygen Concentration Control Mechanism for Interfacial Reaction: In Comparative Example 9, at a high oxygen concentration of 200 ppm, side reactions occurred in the vinylsiloxane segments (oxidative crosslinking rate ≥ 15%), increasing the rigidity of the flame retardant shell and reducing the heat distortion temperature to 135°C (142.5°C in Example 2). By controlling the oxygen concentration to ≤ 50 ppm, Example 2 increased the condensation reaction selectivity to over 95%, ensuring complete interfacial bonding and significantly improving the HDT.

[0088] Dispersion synergistic effect of ultrasonic-shear energy field: In comparative example 5, ultrasonic wave was eliminated and shear force was relied on for dispersion. Nano zinc borate and PTFE powder were not fully deagglomerated, resulting in abnormal increase in melt fluidity (MFR=6.9g / 10min), but there were pore defects inside the material (density decreased by 0.12g / cm 3 ), the thermal deformation temperature is only 129.3℃. Example 2: Ultrasonic cavitation (40kHz) and shear force (5000s -1 ) work synergistically to achieve uniform dispersion of nanoparticles (D90 ≤ 0.8 μm), HDT increased to 142.5 ° C while maintaining process stability (torque fluctuation coefficient 8.3%).

[0089] Test Example 4: Long-term stability and comprehensive performance experiment Experimental purpose: To verify the effects of dynamic process formula, hyperbranched dispersant generation and oxygen concentration on the long-term aging resistance, thermal stability and comprehensive mechanical properties of the material.

[0090] The experimental steps are as follows: Sample preparation: Standard test specimens were prepared according to the formulations and processes of Example 3, Comparative Example 4, Comparative Example 8, and Comparative Example 9.

[0091] Humidity and heat aging test: The specimens were placed in a constant temperature and humidity chamber (85°C / 85% RH) for 1000 hours, and samples were taken every 240 hours to test the mechanical properties.

[0092] Thermogravimetric analysis (TGA): The temperature was raised to 800° C. at a rate of 10° C. / min under a nitrogen atmosphere, and the 5% mass loss temperature (Td5%) and the residual carbon rate were recorded.

[0093] Impact strength retention test: According to GB / T-1843 standard, the notched impact strength before and after damp heat aging was tested, and the retention rate was calculated (after aging / before aging×100%).

[0094] The experimental data are shown in Table 4: Table 4: Comparison of long-term stability and overall performance Test Group Tensile retention after wet heat aging (%) Td5%(℃) Impact strength retention rate (%) Example 3 85.2 312.5 89.7 Comparative Example 4 58.7 285 63.4 Comparative Example 8 72.3 298.6 76.2 Comparative Example 9 73.4 276.8 69.5 Experimental summary: Dynamic process formulas ensure long-term thermal stability: Example 3 uses a dynamic temperature control formula (T = 120 + 0.2N) to ensure uniform condensation reaction between the flame retardant shell and the substrate, resulting in a high tensile retention rate of 85.2% after wet heat aging. Comparative Example 4, however, uses a fixed temperature of 180°C. Local overheating leads to partial decomposition of the shell siloxane (TGA carbon residue rate decreased by 12.5%), deteriorating interfacial bond strength, and retaining only 63.4% of impact strength.

[0095] Ageing resistance mechanism of hyperbranched dispersant generations: The second-generation hyperbranched dispersant in Comparative Example 8 suffers from insufficient branching (≤60%) and an unbalanced amino-epoxy ratio (1:0.5), resulting in reduced molecular chain entanglement ability. Nanoparticles migrate and agglomerate under hot and humid conditions (D90 +40% after aging), resulting in only 72.3% tensile strength retention. The third-generation dispersant in Example 3, through its highly branched topology (≥80%) and 1:1 functional group ratio, forms a stable "anchor-entanglement" network, improving impact strength retention to 89.7%.

[0096] Low oxygen concentration protects interfacial chemical bonds: When processed under a high oxygen concentration (200 ppm), the vinylsiloxane segments in Comparative Example 9 oxidatively crosslinked (FTIR C=O peak intensity increased by 22%), embrittled the flame retardant shell, and reduced Td5% to 276.8°C (312.5°C in Example 3). By controlling the oxygen concentration to ≤50 ppm, Example 3 suppressed oxidative side reactions, maintaining intact interfacial condensation bonds and increasing the carbon residue to 28.6% (compared to 19.3% in Comparative Example 9).

[0097] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A highly dispersed halogen-free flame retardant polyether polyol composite material, characterized in that: The composition includes the following parts by weight: Polyether polyol matrix: 60-75 parts; Core-shell synergistic flame retardant: 20-30 parts; Hyperbranched polysiloxane dispersant: 3-5 parts; Nano zinc borate synergist: 2-5 parts; Anti-dripping agent: 0.5-1 part.

2. A highly dispersed halogen-free flame retardant polyether polyol composite material according to claim 1, characterized in that: The polyether polyol matrix has a hydroxyl value of 42-48 mgKOH / g and a molecular weight of 3000-5000; the core layer of the core-shell synergistic flame retardant is phosphorus-nitrogen synergistic nanoparticles, and the shell layer is a vinyl silicone-polyether block copolymer, wherein the molar ratio of the silicone segment to the polyether segment is 1:2-1:

3.

3. The highly dispersed halogen-free flame retardant polyether polyol composite material according to claim 1, characterized in that: The hyperbranched polysiloxane dispersant is a third-generation hyperbranched structure, the terminal functional groups are amino and epoxy groups, and the molar ratio of amino to epoxy groups is 1:

1.

4. The highly dispersed halogen-free flame retardant polyether polyol composite material according to claim 1, characterized in that: The nano zinc borate synergist has a particle size of 50-100 nm and its surface is modified with organosiloxane; the anti-dripping agent is polytetrafluoroethylene powder with a particle size of 1-2 μm.

5. A method for preparing a highly dispersed halogen-free flame retardant polyether polyol composite material, applied to a highly dispersed halogen-free flame retardant polyether polyol composite material according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, dissolving DOPO flame retardant and melamine polyphosphate in a solvent, heating and reacting, separating and drying to obtain phosphorus-nitrogen synergistic core layer particles; The core layer particles are dispersed in a vinyl siloxane-polyether block copolymer solution, an initiator is added, and the mixture reacts under an inert atmosphere to form a core-shell structure flame retardant; S2, premixing the polyether polyol matrix, the core-shell synergistic flame retardant, and the hyperbranched polysiloxane dispersant to form a homogeneous slurry to obtain a premix; S3, feeding the premix into a twin-screw reaction extruder, and dynamically adjusting the temperature and screw speed to cause a condensation reaction between the shell siloxane and the polyether polyol to form a chemically bonded interface; S4, adding nano zinc borate synergist and anti-dripping agent to the molten material, and simultaneously applying ultrasonic cavitation and high-speed shear force to achieve nano-scale dispersion; S5. The dispersed melt is pelletized through an underwater pelletizing process, and the composite material particles are obtained after drying.

6. The method for preparing a highly dispersed halogen-free flame retardant polyether polyol composite material according to claim 5, characterized in that: In step S1, DOPO flame retardant and melamine polyphosphate are dissolved in ethanol solvent at a mass ratio of 1:1.1-1:1.3, the pH is adjusted to 4.0-5.0 at a reaction temperature of 78-82° C., the reaction is carried out for 3.5-4.5 hours, the precipitate is separated by centrifugation at a centrifugal speed of 8000-10000 rpm, and the precipitate is vacuum-dried at 60° C. for 12 hours to obtain phosphorus-nitrogen synergistic core layer particles; The core layer particles are dispersed in a vinyl silicone-polyether block copolymer solution with a molar ratio of silicone to polyether segments of 1:2-1:3, 0.4-0.6 wt% of azobisisobutyronitrile as a free radical initiator is added, and the mixture is reacted at 68-72° C. under nitrogen protection for 5.5-6.5 hours, with a centrifugal speed of 6000-8000 rpm. The product is vacuum dried at 50° C. for 8 hours to obtain a core-shell flame retardant with a shell thickness of 10-20 nm.

7. The method for preparing a highly dispersed halogen-free flame retardant polyether polyol composite material according to claim 5, characterized in that: In step S2, the polyether polyol matrix, the core-shell synergistic flame retardant, and the hyperbranched polysiloxane dispersant are added to a premixer at a premixing speed of 480-520 rpm, for 9-11 minutes, at a temperature of 22-28° C. to form a homogeneous slurry to obtain a premix.

8. The method for preparing a highly dispersed halogen-free flame retardant polyether polyol composite material according to claim 5, characterized in that: In step S3, the premix is fed into a twin-screw reaction extruder at a screw speed of 200-300 rpm and a barrel temperature according to the formula T=120+0.2N, where T is the temperature of the twin-screw reaction extruder and N is the screw speed, corresponding to a temperature of 160-180°C, a residence time of 5-8 minutes, and an oxygen concentration of 40-50 ppm, so that the shell siloxane and the polyether polyol hydroxyl groups condense to form a chemically bonded interface.

9. The method for preparing a highly dispersed halogen-free flame retardant polyether polyol composite material according to claim 5, characterized in that: In step S4, nano zinc borate synergist and anti-dripping agent are added to the molten material, and ultrasonic waves with a frequency of 40kHz, a power of 500W, and a shear rate of 5000-8000s are simultaneously applied. -1 , the ultrasonic action time accounts for 60-70%, the total dispersion time is 15-20min, and the treated melt is obtained.

10. The method for preparing a highly dispersed halogen-free flame retardant polyether polyol composite material according to claim 5, characterized in that: In step S5, the melt is pelletized by an underwater pelletizer, the pelletizing water temperature is 10-15° C., the pelletizing speed is 200-300 rpm, the particle size is 2-3 mm, and the pellets are vacuum dried at 50° C. for 4 hours, the moisture content is 0.05-0.1%, and the pellets are sealed and packaged.

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