Preparation method of high-flame-retardant polyurethane based on multi-component proportion adjustment

Abstract

The invention relates to the technical field of polyurethane material preparation, in particular to a preparation method of high-flame-retardant polyurethane based on multi-component proportion adjustment. According to the method, through the synergistic effect of the bromine-containing flame-retardant polyether polyol and the flame-retardant polyester, the optimized combination of the phosphorus flame retardant and the plasticizer, the precise control of the double metal cyanide catalyst, the application of the environment-friendly physical foaming agent and the dynamic adjustment mechanism of the component A, the flame-retardant property, the mechanical property and the environment-friendly property of the material are remarkably improved; meanwhile, the preparation process is simplified, and the production cost is reduced. The high-flame-retardant polyurethane material is suitable for high-standard requirements of modern industry on the high-flame-retardant polyurethane material.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane material preparation, and in particular relates to a method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment. Background Art

[0002] As a polymer material with excellent properties, polyurethane is widely used in the fields of construction, automobiles, electronic products, etc. Especially in terms of flame retardancy, the research and application of highly flame retardant polyurethane has received more and more attention. However, the existing preparation methods of highly flame retardant polyurethane still have some shortcomings in terms of flame retardant effect, mechanical properties and environmental protection, which are difficult to meet the high standards of modern industry.

[0003] The patent "Flame-retardant and high-temperature resistant two-component polyurethane structural adhesive" with publication number CN115785879B provides a two-component polyurethane structural adhesive, which achieves V-0 flame retardancy and high high-temperature shear strength through a specific component ratio and modified bio-based polyols. However, in this technical solution, the source and preparation process of the specific bio-based polyols used are relatively complicated, which may lead to increased costs. In addition, the stability of this structural adhesive under long-term high-temperature use conditions still needs to be further verified, which may affect its application in some extreme environments.

[0004] The patent "High-strength flame-retardant polyurethane rigid foam and its preparation method" with publication number CN117327251B uses phosphorus-containing flame-retardant polyester polyols and nitrogen-containing polyether polyols to prepare polyurethane rigid foams with high strength and excellent flame retardant properties by utilizing the synergistic effect of nitrogen and phosphorus in the polyol composition. However, in this technical solution, the proportion adjustment of multiple components is relatively complicated, and the compatibility and reaction conditions between different components are difficult to control, which may increase the complexity of the process flow. In addition, this method may require higher equipment investment and operating skills in actual production, which increases production costs and process difficulty.

[0005] The above problems indicate that the existing methods for preparing highly flame-retardant polyurethane still have certain deficiencies in terms of flame-retardant effect, mechanical properties, cost control, and process complexity. Therefore, the present invention provides a method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment, aiming to optimize the compatibility and reaction conditions of the multiple components, simplify the preparation process, reduce production costs, and achieve higher flame-retardant effect and mechanical properties, thereby meeting the high standard requirements of modern industry for highly flame-retardant polyurethane. Summary of the invention

[0006] The present invention provides a method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment, which solves the deficiencies of the existing method for preparing highly flame-retardant polyurethane in terms of flame-retardant effect, mechanical properties, environmental protection, cost control and process complexity. The present invention aims to provide a technical solution for optimizing multi-component compatibility and reaction conditions, simplifying the preparation process, reducing production costs, and improving flame-retardant effect and mechanical properties, so as to meet the high standard requirements of modern industry for highly flame-retardant polyurethane.

[0007] The technical solution adopted by the present invention to solve the above technical problems is: a preparation method of highly flame-retardant polyurethane based on multi-component proportion adjustment, which comprises, by weight, component A, 30-50 parts of bromine-containing flame-retardant polyether polyol, 5-10 parts of flame-retardant polyester, 20-30 parts of flame retardant, 5-10 parts of double metal cyanide catalyst and 5-10 parts of plasticizer, and component B uses 30 parts of polyphenyl polymethylene isocyanate; the component A is adjusted in different proportions according to different production environments on site, and the best casting effect is achieved by adjusting the different proportions of the component A.

[0008] Preferably, the flame retardant is a phosphorus-based flame retardant.

[0009] Specifically, the low molecular weight bromide is low molecular weight brominated polystyrene (BPS), brominated SBS (styrene-butadiene block copolymer) and brominated epoxy resin; preferably low molecular weight brominated polystyrene.

[0010] Specifically, the plasticizer activator is dioctyl phthalate, carbamate and di(2-ethyl)hexyl phthalate; preferably dioctyl phthalate.

[0011] Specifically, the bromine-containing flame-retardant polyether polyol and the flame-retardant polyester are uniformly mixed in a reaction container by mechanical stirring, and a low molecular weight bromide catalyst is added during the mixing process. The amount of the low molecular weight bromide catalyst is 0.5-1.0% of the total weight of the bromine-containing flame-retardant polyether polyol and the flame-retardant polyester.

[0012] Specifically, the phosphorus flame retardant and the plasticizer in the flame retardant are premixed by a high-speed stirrer before the reaction, and a plasticizer activator is added during the premixing process. The amount of the plasticizer activator is 1-2% of the total weight of the plasticizer.

[0013] Specifically, the double metal cyanide catalyst is added in batches during the reaction through a multi-stage feeding device, which includes multiple storage tanks and a metering pump. The metering pump adjusts the amount of catalyst added in each batch according to the instructions of the control unit.

[0014] Specifically, the physical foaming agent is mixed with component A through a physical foaming agent mixing and spraying device before the reaction. The physical foaming agent mixing and spraying device includes a high-speed stirrer and a gas-liquid mixer. The stirring speed of the high-speed stirrer is 1000-3000 rpm, and the gas-liquid mixing ratio of the gas-liquid mixer is 1:10-20.

[0015] Specifically, the reaction state and physical properties of the material are monitored in real time through an online monitoring system, and the proportion of each component in component A is dynamically adjusted according to the monitoring results to ensure the optimal performance of the material under different environmental conditions; the online monitoring system includes sensors, data acquisition modules, control units and actuators.

[0016] Specifically, polyphenyl polymethylene isocyanate is mixed with component A through a multi-point injection device during the reaction process. The multi-point injection device includes multiple injection heads and a pressure regulating valve. The injection heads are evenly distributed at multiple positions of the reaction container. The distance between the injection heads is 10-20 cm. The adjustment range of the pressure regulating valve is 0-100 bar.

[0017] Specifically, the A component mixing device includes a high-speed stirrer and a low molecular weight bromide catalyst feed port.

[0018] Specifically, the physical foaming agent mixing and injection device includes a high-speed stirrer and a gas-liquid mixer, and the gas-liquid mixer includes a gas-liquid mixing ratio regulating valve.

[0019] Specifically, the multi-stage feeding device includes a storage tank and a metering pump, and the metering pump includes a multi-stage feeding device control valve.

[0020] Preferably, in the improvement of the synergistic effect of bromine-containing flame-retardant polyether polyol and flame-retardant polyester, the bromine-containing flame-retardant polyether polyol and the flame-retardant polyester are uniformly mixed in a reaction container by mechanical stirring, and a low molecular weight bromide catalyst is added during the mixing process, so that the bromine-containing flame-retardant polyether polyol generates low molecular weight bromide during the reaction process, and the flame-retardant polyester improves the thermal stability of the material through its three-dimensional network structure. The amount of the low molecular weight bromide catalyst is 0.5-1.0% of the total weight of the bromine-containing flame-retardant polyether polyol and the flame-retardant polyester.

[0021] Preferably, in the optimized combination of flame retardant and plasticizer, the phosphorus flame retardant in the flame retardant and the plasticizer are premixed before the reaction, and an activator of the plasticizer is added during the premixing process. The activator can enhance the interaction between the plasticizer and the polyurethane molecular chain and improve the flexibility and impact resistance of the material. The amount of the plasticizer activator is 1-2% of the total weight of the plasticizer.

[0022] Preferably, in the precise control of the catalyst, the double metal cyanide catalyst is added in batches through a multi-stage feeding device during the reaction process, and the amount of each batch added is dynamically adjusted according to the real-time data of the online monitoring system to ensure the uniformity of the reaction and the stability of the material. The multi-stage feeding device includes multiple storage tanks and metering pumps, and the metering pump adjusts the amount of each batch of catalyst added according to the instructions of the control unit.

[0023] Preferably, in the application of the environmentally friendly physical foaming agent, the physical foaming agent is mixed with component A by a mixing spray device before the reaction, and the mixing spray device includes a high-speed stirrer and a gas-liquid mixer. The high-speed stirrer can fully mix the physical foaming agent with component A, and the gas-liquid mixer can ensure the uniform distribution of the foaming agent in component A. The stirring speed of the mixing spray device is 1000-3000 rpm, and the gas-liquid mixing ratio of the gas-liquid mixer is 1:10-1:20.

[0024] Preferably, in the dynamic adjustment mechanism of component A, the control unit calculates the optimal ratio of each component in component A through a preset algorithm based on the temperature, pressure, density and other parameters collected by the sensor, and dynamically adjusts the addition amount of each component through the actuator. The calculation algorithm of the control unit includes fuzzy logic control and neural network prediction. The fuzzy logic control is used to adjust the addition amount of each component in real time, and the neural network prediction is used to predict the change trend during the reaction process to ensure the stability and consistency of material performance.

[0025] Preferably, in the optimized use of polyphenyl polymethylene isocyanate, the polyphenyl polymethylene isocyanate is mixed with component A through a multi-point injection device during the reaction, and the multi-point injection device includes multiple injection heads and a pressure regulating valve, and the injection heads are evenly distributed at multiple positions of the reaction container. The pressure regulating valve is used to adjust the injection pressure of the polyphenyl polymethylene isocyanate to ensure the uniformity of the reaction and the stability of the material. The injection head spacing of the multi-point injection device is 10-20 cm, and the adjustment range of the pressure regulating valve is 0-100 bar.

[0026] The bromine-containing flame-retardant polyether polyol of the present invention and the flame-retardant polyester have a synergistic effect: the bromine-containing flame-retardant polyether polyol and the flame-retardant polyester are uniformly mixed in a reaction container by mechanical stirring, and a catalyst of a low molecular weight bromide is added during the mixing process, so that the bromine-containing flame-retardant polyether polyol generates a low molecular weight bromide during the reaction process, and the flame-retardant polyester improves the thermal stability of the material through its three-dimensional network structure. The low molecular weight bromide can effectively capture free radicals, inhibit the chain propagation of the combustion reaction, and reduce the generation of smoke and toxic gases during combustion. The phosphorus-based flame retardant and the plasticizer in the flame retardant are premixed with a high-speed stirrer before the reaction, and an activator of the plasticizer is added during the premixing process. The activator can enhance the interaction between the plasticizer and the polyurethane molecular chain, and improve the flexibility and impact resistance of the material. The stirring speed of the high-speed stirrer is 1000-3000 rpm, and the amount of the activator added is 1-2% of the total weight of the plasticizer. The physical foaming agent is mixed with component A through a mixing spray device before the reaction. The mixing spray device includes a high-speed stirrer and a gas-liquid mixer. The high-speed stirrer can fully mix the physical foaming agent with component A, and the gas-liquid mixer can ensure the uniform distribution of the foaming agent in component A. The stirring speed of the high-speed stirrer is 1000-3000 rpm, and the gas-liquid mixing ratio of the gas-liquid mixer is 1:10-20. The addition of the physical foaming agent improves the density and uniformity of the foam, reduces the shrinkage rate of the material, and improves the physical properties of the material. The polyphenyl polymethylene isocyanate is mixed with component A through a multi-point spray device during the reaction. The multi-point spray device includes a plurality of spray heads and a pressure regulating valve. The spray heads are evenly distributed at multiple positions of the reaction container. The pressure regulating valve is used to adjust the spray pressure of the polyphenyl polymethylene isocyanate to ensure the uniformity of the reaction and the stability of the material. The spray head spacing of the multi-point spray device is 10-20 cm, and the adjustment range of the pressure regulating valve is 0-100 bar. Polyphenyl polymethylene isocyanate undergoes a cross-linking reaction with components such as polyols and flame retardants in component A to form a polyurethane foam with a three-dimensional network structure. This structure not only improves the mechanical properties of the material, but also enhances the heat resistance and flame retardancy of the material.

[0027] Beneficial effects of the present invention: The present invention significantly improves the flame retardant properties of polyurethane foam, reduces the generation of smoke and toxic gases during combustion, and improves the safety and environmental protection of the material through the synergistic effect of bromine-containing flame retardant polyether polyol and flame retardant polyester, and the use of phosphorus flame retardants. By adding plasticizers, the flexibility and impact resistance of the material are improved, so that the material can still maintain good flexibility under low temperature conditions. At the same time, the uniformity and stability of the material are ensured through precise control of the catalyst. The use of non-volatile physical foaming agents not only improves the foaming efficiency and stability of the material, but also ensures the environmental protection performance of the material, reduces pollution to the environment, and meets the needs of modern society for environmentally friendly materials. DETAILED DESCRIPTION

[0028] The present invention is described in detail below by way of examples. Unless otherwise specified, all raw materials used are commercially available.

[0029] The bromine-containing flame-retardant polyether polyol involved in the present invention includes 4,4,4-tribromo-1,2-epoxybutylene polyether or 4-bromo-1,2-epoxybutylene polyether. The flame-retardant polyester adopts the LPS series of Liansheng Company, specifically including LPS-2235 or LPS-2260N, wherein the hydroxyl value of LPS-2235 is 235±15 mgKOH / g and the viscosity is 11000±2000mPa·s; the hydroxyl value of LPS-2260N is 265±10mgKOH / g and the viscosity is 9000±2500mPa·s. The phosphorus-based flame retardant adopts triphenyl phosphate or tricresyl phosphate; the plasticizer is epoxy soybean oil and dioctyl phthalate.

[0030] The double metal cyanide catalyst is zinc-cobalt cyanide, and the synthesis steps are: Precursor: Zinc nitrate (Zn(NO 3 ) 2 ) + Cobalt nitrate (Co(NO 3 ) 2 ) was dissolved in DMF at a molar ratio of 1:1.

[0031] Precipitation: Add KCN dropwise and react at 60°C for 6 hours.

[0032] Post-treatment: acid stripping (dilute sulfuric acid + propionic acid), centrifugation, drying.

[0033] Example 1

[0034] A specific embodiment of a method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment comprises the following steps:

[0035] S1. Mixing of component A: 35 parts of 4,4,4-tribromo-1,2-butylene oxide polyether, 7 parts of LPS-2235, 6 parts of plasticizer (epoxidized soybean oil) and 3 parts of double metal cyanide catalyst are weighed in proportion and added to the mixing device of component A. Start the high-speed stirrer to stir and mix evenly. At the same time, add low molecular weight brominated polystyrene (the amount is 0.8% of the total weight of bromine-containing flame-retardant polyether polyol and flame-retardant polyester) through the feed port during the mixing process to ensure that the catalyst is evenly distributed.

[0036] S2. Premixing: 25 parts of triphenyl phosphate and plasticizer are premixed with a high-speed stirrer in a premixing device, and 1 part of dioctyl phthalate is added to ensure that the dioctyl phthalate is evenly distributed.

[0037] S3. Physical foaming agent mixing: Supercritical carbon dioxide is mixed with component A through a physical foaming agent mixing injection device. A high-speed stirrer is started for stirring and mixing, and a gas-liquid mixer is used to ensure uniform distribution of the foaming agent in component A. The stirring speed of the high-speed stirrer is 2000 rpm, and the gas-liquid mixing ratio of the gas-liquid mixer is 1:15.

[0038] S4. Catalyst feeding: zinc-cobalt cyanide is added into the reaction vessel through a multi-stage feeding device.

[0039] S5. Injection of component B: 30 parts of polyphenyl polymethylene isocyanate are mixed with component A through a multi-point injection device. The multi-point injection device includes multiple injection heads and a pressure regulating valve. The injection heads are evenly distributed at different positions of the reaction container (with a spacing of 15 cm). The pressure regulating valve is used to adjust the injection pressure of polyphenyl polymethylene isocyanate (the adjustment range is 50 bar).

[0040] S6. Casting and curing: Pour the mixed components A and B into the mold for casting, and cure at a certain temperature. Appearance: The surface of the cured polyurethane material is smooth without obvious bubbles or cracks.

[0041] Appearance: The surface of the cured polyurethane material is smooth without obvious bubbles or cracks.

[0042] Flame retardant performance: passed the vertical burning test and reached UL-94V0 level.

[0043] Example 2

[0044] A specific embodiment of a method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment comprises the following steps:

[0045] S1. Mixing of component A: Weigh 40 parts of 4-bromo-1,2-butylene oxide polyether, 5 parts of LPS-2235, 3 parts of plasticizer (epoxidized soybean oil) and 10 parts of double metal cyanide catalyst in proportion and add them to the mixing device of component A. Start the high-speed stirrer to stir and mix evenly. At the same time, add low molecular weight brominated polystyrene (the amount is 0.8% of the total weight of bromine-containing flame-retardant polyether polyol and flame-retardant polyester) through the feed port during the mixing process to ensure that the catalyst is evenly distributed.

[0046] S2. Premixing: 20 parts of triphenyl phosphate and plasticizer are premixed with a high-speed stirrer in a premixing device, and 2 parts of dioctyl phthalate are added to ensure that the dioctyl phthalate is evenly distributed.

[0047] S3. Physical foaming agent mixing: non-volatile environmentally friendly physical foaming agent (supercritical carbon dioxide) is mixed with component A through a physical foaming agent mixing and spraying device. The high-speed stirrer is started for stirring and mixing, and the uniform distribution of the foaming agent in component A is ensured by the gas-liquid mixer. The stirring speed of the high-speed stirrer is 2000 rpm, and the gas-liquid mixing ratio of the gas-liquid mixer is 1:15.

[0048] S4. Catalyst feeding: zinc-cobalt cyanide is added into the reaction vessel through a multi-stage feeding device.

[0049] S5. Injection of component B: 30 parts of polyphenyl polymethylene isocyanate are mixed with component A through a multi-point injection device. The multi-point injection device includes multiple injection heads and a pressure regulating valve. The injection heads are evenly distributed at different positions of the reaction container (with a spacing of 10 cm). The pressure regulating valve is used to adjust the injection pressure of polyphenyl polymethylene isocyanate (the adjustment range is 50 bar).

[0050] S6. Casting and curing: Pour the mixed components A and B into the mold for casting, and cure at a certain temperature. Appearance: The surface of the cured polyurethane material is smooth without obvious bubbles or cracks.

[0051] Appearance: The surface of the cured polyurethane material is smooth without obvious bubbles or cracks.

[0052] Flame retardant performance: passed the vertical burning test and reached UL-94V0 level.

[0053] Example 3

[0054] A specific embodiment of a method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment comprises the following steps:

[0055] S1. Mixing of component A: 30 parts of 4,4,4-tribromo-1,2-butylene oxide polyether, 5 parts of LPS-2235, 8 parts of plasticizer (epoxidized soybean oil) and 10 parts of double metal cyanide catalyst are weighed in proportion and added to the mixing device of component A. Start the high-speed agitator to stir and mix evenly. At the same time, add low molecular weight brominated polystyrene (the amount is 0.8% of the total weight of bromine-containing flame-retardant polyether polyol and flame-retardant polyester) through the feed port during the mixing process to ensure that the catalyst is evenly distributed.

[0056] S2. Premixing: 30 parts of triphenyl phosphate and plasticizer are premixed with a high-speed stirrer in a premixing device, and 2 parts of dioctyl phthalate are added to ensure that the dioctyl phthalate is evenly distributed.

[0057] S3. Physical foaming agent mixing: non-volatile environmentally friendly physical foaming agent (supercritical carbon dioxide) is mixed with component A through a physical foaming agent mixing and spraying device. The high-speed stirrer is started for stirring and mixing, and the uniform distribution of the foaming agent in component A is ensured by the gas-liquid mixer. The stirring speed of the high-speed stirrer is 2000 rpm, and the gas-liquid mixing ratio of the gas-liquid mixer is 1:15.

[0058] S4. Catalyst feeding: zinc-cobalt cyanide is added into the reaction vessel through a multi-stage feeding device.

[0059] S5. Injection of component B: 30 parts of polyphenyl polymethylene isocyanate are mixed with component A through a multi-point injection device. The multi-point injection device includes multiple injection heads and a pressure regulating valve. The injection heads are evenly distributed at different positions of the reaction container (with a spacing of 15 cm). The pressure regulating valve is used to adjust the injection pressure of polyphenyl polymethylene isocyanate (the adjustment range is 100 bar).

[0060] S6. Casting and curing: Pour the mixed components A and B into the mold for casting, and cure at a certain temperature. Appearance: The surface of the cured polyurethane material is smooth without obvious bubbles or cracks.

[0061] Appearance: The surface of the cured polyurethane material is smooth without obvious bubbles or cracks.

[0062] Flame retardant performance: passed the vertical burning test and reached UL-94V0 level.

[0063] Example 4

[0064] A specific embodiment of a method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment comprises the following steps:

[0065] S1. Mixing of component A: Weigh 40 parts of 4,4,4-tribromo-1,2-butylene oxide polyether, 5 parts of LPS-2235, 3 parts of plasticizer (epoxidized soybean oil) and 5 parts of double metal cyanide catalyst in proportion and add them to the mixing device of component A. Start the high-speed agitator to stir and mix evenly. At the same time, add low molecular weight brominated polystyrene (the amount is 0.8% of the total weight of bromine-containing flame-retardant polyether polyol and flame-retardant polyester) through the feed port during the mixing process to ensure that the catalyst is evenly distributed.

[0066] S2. Premixing: 20 parts of triphenyl phosphate and plasticizer are premixed with a high-speed stirrer in a premixing device, and 2 parts of dioctyl phthalate are added to ensure that the dioctyl phthalate is evenly distributed.

[0067] S3. Physical foaming agent mixing: non-volatile environmentally friendly physical foaming agent (supercritical carbon dioxide) is mixed with component A through a physical foaming agent mixing and spraying device. The high-speed stirrer is started for stirring and mixing, and the uniform distribution of the foaming agent in component A is ensured by the gas-liquid mixer. The stirring speed of the high-speed stirrer is 1500 rpm, and the gas-liquid mixing ratio of the gas-liquid mixer is 1:30.

[0068] S4. Catalyst feeding: zinc-cobalt cyanide is added into the reaction vessel through a multi-stage feeding device.

[0069] S5. Injection of component B: 30 parts of polyphenyl polymethylene isocyanate are mixed with component A through a multi-point injection device. The multi-point injection device includes multiple injection heads and a pressure regulating valve. The injection heads are evenly distributed at different positions of the reaction container (with a spacing of 15 cm). The pressure regulating valve is used to adjust the injection pressure of polyphenyl polymethylene isocyanate (the adjustment range is 0 bar).

[0070] S6. Casting and curing: Pour the mixed components A and B into the mold for casting, and cure at a certain temperature. Appearance: The surface of the cured polyurethane material is smooth without obvious bubbles or cracks.

[0071] Appearance: The surface of the cured polyurethane material is smooth without obvious bubbles or cracks.

[0072] Flame retardant performance: passed the vertical burning test and reached UL-94V0 level.

[0073] Example 5

[0074] A specific embodiment of a method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment comprises the following steps:

[0075] S1. Mixing of component A: 33 parts of 4,4,4-tribromo-1,2-butylene oxide polyether, 6 parts of LPS-2235, 7 parts of plasticizer (epoxidized soybean oil) and 7 parts of double metal cyanide catalyst are weighed in proportion and added to the mixing device of component A. Start the high-speed agitator to stir and mix evenly. At the same time, add low molecular weight brominated polystyrene (the amount is 0.8% of the total weight of bromine-containing flame-retardant polyether polyol and flame-retardant polyester) through the feed port during the mixing process to ensure that the catalyst is evenly distributed.

[0076] S2. Premixing: 10 parts of triphenyl phosphate and plasticizer are premixed with a high-speed stirrer in a premixing device, and 3 parts of dioctyl phthalate are added to ensure that the dioctyl phthalate is evenly distributed.

[0077] S3. Physical foaming agent mixing: non-volatile environmentally friendly physical foaming agent (supercritical carbon dioxide) is mixed with component A through a physical foaming agent mixing and spraying device. The high-speed stirrer is started for stirring and mixing, and the uniform distribution of the foaming agent in component A is ensured by the gas-liquid mixer. The stirring speed of the high-speed stirrer is 1500 rpm, and the gas-liquid mixing ratio of the gas-liquid mixer is 1:30.

[0078] S4. Catalyst feeding: zinc-cobalt cyanide is added into the reaction vessel through a multi-stage feeding device.

[0079] S5. Injection of component B: 30 parts of polyphenyl polymethylene isocyanate are mixed with component A through a multi-point injection device. The multi-point injection device includes multiple injection heads and a pressure regulating valve. The injection heads are evenly distributed at different positions of the reaction container (with a spacing of 15 cm). The pressure regulating valve is used to adjust the injection pressure of polyphenyl polymethylene isocyanate (the adjustment range is 0 bar).

[0080] S6. Casting and curing: Pour the mixed components A and B into the mold for casting, and cure at a certain temperature. Appearance: The surface of the cured polyurethane material is smooth without obvious bubbles or cracks.

[0081] Flame retardant performance: passed the vertical burning test and reached UL-94V0 level.

[0082] Example 6

[0083] A specific embodiment of a method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment comprises the following steps:

[0084] S1. Mixing of component A: 50 parts of 4,4,4-tribromo-1,2-butylene oxide polyether, 10 parts of LPS-2260N, 6 parts of plasticizer (epoxidized soybean oil) and 7 parts of double metal cyanide catalyst are weighed in proportion and added to the mixing device of component A. Start the high-speed agitator to stir and mix evenly. At the same time, add low molecular weight brominated polystyrene (the amount is 0.8% of the total weight of bromine-containing flame-retardant polyether polyol and flame-retardant polyester) through the feed port during the mixing process to ensure that the catalyst is evenly distributed.

[0085] S2. Premixing: 10 parts of tricresyl phosphate and plasticizer are premixed with a high-speed stirrer in a premixing device, and 2 parts of dioctyl phthalate are added to ensure that the dioctyl phthalate is evenly distributed.

[0086] S3. Physical foaming agent mixing: non-volatile environmentally friendly physical foaming agent (supercritical carbon dioxide) is mixed with component A through a physical foaming agent mixing injection device. The high-speed stirrer is started for stirring and mixing, and the gas-liquid mixer is used to ensure uniform distribution of the foaming agent in component A. The stirring speed of the high-speed stirrer is 1500 rpm, and the gas-liquid mixing ratio of the gas-liquid mixer is 1:10.

[0087] S4. Catalyst feeding: zinc-cobalt cyanide is added into the reaction vessel through a multi-stage feeding device.

[0088] S5. Injection of component B: 30 parts of polyphenyl polymethylene isocyanate are mixed with component A through a multi-point injection device. The multi-point injection device includes multiple injection heads and a pressure regulating valve. The injection heads are evenly distributed at different positions of the reaction container (with a spacing of 19 cm). The pressure regulating valve is used to adjust the injection pressure of polyphenyl polymethylene isocyanate (the adjustment range is 88 bar).

[0089] S6. Casting and curing: Pour the mixed components A and B into the mold for casting, and cure at a certain temperature. Appearance: The surface of the cured polyurethane material is smooth without obvious bubbles or cracks.

[0090] Appearance: The surface of the cured polyurethane material is smooth without obvious bubbles or cracks.

[0091] Flame retardant performance: passed the vertical burning test and reached UL-94V0 level.

[0092] Flame retardancy test: UL94 grade of Examples 1-6 is V-0, and the limiting oxygen index (LOI) is ≥28%; thermal stability: TGA data shows that the decomposition temperature is ≥300°C (N 2 atmosphere); Catalyst efficiency: DMC catalyst shortens the polymerization reaction time to 2 hours (compared to 8 hours without catalyst).

[0093]

[0094] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment, characterized in that: By weight, the component A comprises 30-50 parts of bromine-containing flame-retardant polyether polyol, 5-10 parts of flame-retardant polyester, 20-30 parts of flame retardant, 5-10 parts of double metal cyanide catalyst and 5-10 parts of plasticizer, and the component B uses 30 parts of polyphenyl polymethylene isocyanate.

2. The method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment according to claim 1, characterized in that: The bromine-containing flame-retardant polyether polyol and the flame-retardant polyester are uniformly mixed in a reaction container by mechanical stirring, and a low molecular weight bromide catalyst is added during the mixing process. The amount of the low molecular weight bromide catalyst is 0.5%-1.0% of the total weight of the bromine-containing flame-retardant polyether polyol and the flame-retardant polyester.

3. The method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment according to claim 1, characterized in that: The phosphorus flame retardant and the plasticizer in the flame retardant are premixed by a high-speed stirrer before the reaction. During the premixing process, a plasticizer activator is added. The amount of the plasticizer activator is 1%-2% of the total weight of the plasticizer.

4. The method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment according to claim 1, characterized in that: The double metal cyanide catalyst is added in batches during the reaction process through a multi-stage feeding device, which includes a plurality of storage tanks and a metering pump.

5. The method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment according to claim 1, characterized in that: A physical foaming agent is also added during the preparation process. The physical foaming agent is mixed with component A through a physical foaming agent mixing and spraying device before the mixing reaction of components A and B. The physical foaming agent mixing and spraying device includes a high-speed stirrer and a gas-liquid mixer. The stirring speed of the high-speed stirrer is 1000-3000 rpm, and the gas-liquid mixing ratio of the gas-liquid mixer is 1:10-20.

6. The method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment according to claim 1, characterized in that: During the reaction, polyphenyl polymethylene isocyanate is mixed with component A through a multi-point injection device, which includes multiple injection heads and a pressure regulating valve. The injection heads are evenly distributed at multiple positions of the reaction container, the injection head spacing is 10-20 cm, and the pressure regulating valve has an adjustment range of 0-100 bar.

7. The method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment according to claim 1, characterized in that: The A component mixing device includes a high-speed stirrer and a low molecular weight bromide catalyst feed port.

8. The method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment according to claim 5, characterized in that: The gas-liquid mixer comprises a gas-liquid mixing ratio regulating valve.

9. The method for preparing highly flame-retardant polyurethane based on multi-component ratio adjustment according to claim 4, characterized in that: The metering pump includes a multi-stage charging device control valve.

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