Ultrahigh-porosity-density polyurethane material and preparation method thereof

Abstract

The invention provides a preparation method of an ultrahigh-porosity-density polyurethane material, which comprises the following steps: respectively preparing a precursor component and a functional chain extension component, injecting inert gas into the precursor component in a periodic pulse mode to form microbubbles, monitoring bubble distribution parameters in real time in the gas injection process, and controlling the average radius of the microbubbles to be within 30-80 [mu] m to obtain the ultrahigh-porosity-density polyurethane material. Adding a functional chain extension component in the state, and shearing and mixing at a high speed to obtain a mixture, so that the microbubbles are stably dispersed and directionally arranged in the mixture; and injecting the mixture into a curing device with temperature and pressure regulation and control functions, and curing to obtain the ultrahigh-porosity-density polyurethane material. In the gas injection stage, the bubble generation time is separated through a pulse gas injection mode, the merging opportunity between bubbles is reduced, in the curing stage, through a low-pressure environment and long-time curing, the bubbles are prevented from being broken due to rapid curing, the number of microbubbles in unit volume is increased, and the porosity of the polyurethane material is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane materials, and in particular relates to an ultra-high pore density polyurethane material and a preparation method thereof. Background Art

[0002] Polyurethane materials can be used as thermal insulation materials, sound-absorbing materials, flexible materials, etc., and are applied to building insulation, automobile sound insulation, industrial buffering and other fields. Polyurethane materials with high porosity can reduce thermal conductivity by increasing air content, and open pores can also absorb more sound wave energy. Increasing porosity can significantly increase the flow rate of fluids. High-porosity porous structures can effectively reduce material density and reduce the burden on the load-bearing structure.

[0003] In the related art, the foaming process of polyurethane is a complex dynamic process, which is affected by many factors such as temperature, pressure, and chemical reaction rate. During the foaming process, the generation and distribution of bubbles are difficult to accurately control, which can easily lead to uneven distribution of bubble sizes or merging of large bubbles, ultimately affecting the porosity. In addition, during the foaming process, the interaction between bubbles can cause the bubbles to merge or collapse, resulting in a decrease in porosity. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an ultra-high pore density polyurethane material and a preparation method thereof, aiming to solve the problem of low porosity of the polyurethane material.

[0005] In order to solve the above problems, the present invention provides a method for preparing an ultra-high pore density polyurethane material, the steps comprising: S1. Preparing a precursor component and a functional chain extension component respectively, wherein the precursor component comprises a polyol group, a surfactant, a catalyst and a functional regulator, and the functional chain extension component comprises a multifunctional isocyanate and a viscosity diluent; S2, injecting an inert gas into the precursor component in a periodic pulse manner to form microbubbles, and monitoring the bubble distribution parameters in real time during the gas injection process, controlling the average radius of the microbubbles within 30-80 μm, adding the functional chain extension component in this state and mixing at a high speed to obtain a mixture, so that the microbubbles are stably dispersed and oriented in the mixture; S3. Injecting the mixture into a curing device with temperature and pressure control functions, and obtaining an ultra-high pore density polyurethane material after curing, wherein the curing temperature is 30-40° C. and the curing time is 20-25 hours.

[0006] In some embodiments of the present invention, step S1 comprises: S1.1. First, place a polyol group in a stirred reactor, slowly heat it to 23-25°C and continuously introduce an inert gas, and simultaneously dropwise add a surfactant, a catalyst and a functional regulator and stir for 10-15 minutes to obtain a precursor component, wherein the stirring speed is 300-500 rpm, and in the precursor component, calculated by mass percentage, the surfactant accounts for 1-3%, the catalyst accounts for 0.5-1%, the functional regulator accounts for 0.5-2%, and the remainder is the polyol group; S1.2, adding the multifunctional isocyanate to another chamber of the stirred reactor, heating to 20-22°C and stirring for 2-5 minutes, then adding the viscosity diluent, and continuing to stir for 5-10 minutes to obtain a functional chain extension component, wherein the stirring speed is 100-200 rpm, and in the functional chain extension component, the mass ratio of the multifunctional isocyanate to the viscosity diluent is 10-12:1.

[0007] In some embodiments of the present invention, a multi-stage pulse gas transmission module and a control unit are provided inside the stirred reactor, and the multi-stage pulse gas transmission module includes a sensor, a gas transmission device, and a data acquisition interface connected to the control unit signal, and the step S2 includes: S2.1. Set pulse gas transmission parameters and environmental parameters according to the target porosity and expected microbubble radius distribution range; S2.2, injecting inert gas into the precursor component according to the pulse gas transmission parameters and obtaining real-time parameters of microbubbles, and starting stirring at a stirring speed of 300-500 rpm; S2.3, obtaining the average value of the actual radius of microbubbles and calculating the average value of the theoretical radius of microbubbles through the real-time parameters of the microbubbles and the environmental parameters, comparing the average value of the actual radius of microbubbles with the average value of the theoretical radius of microbubbles, and dynamically adjusting the pulse gas delivery parameters and / or the environmental parameters until the average value of the actual radius of microbubbles is within the expected microbubble radius distribution range; S2.4, slowly add the functional chain extension component to the precursor component, maintain the stirring speed at 500-600 rpm, and after the functional chain extension component is added, increase the stirring rate to 1000-1500 rpm and maintain for 10-30 s; S2.5. Determine whether the average actual radius of the microbubbles is maintained within the expected microbubble radius distribution range. If so, reduce the stirring speed to 500-600 rpm and maintain for 1-2 minutes to obtain a mixture. If not, continue stirring until the average actual radius of the microbubbles is within the expected microbubble radius distribution range.

[0008] In some embodiments of the present invention, in step S2.3, the calculation formula of the average value of the theoretical radius of microbubbles is: in, is the average theoretical radius of microbubbles, is the preset porosity, is the real-time number of microbubbles per unit volume, is the correction factor to take into account the non-uniformity of microbubble distribution, is the standard deviation of the microbubble radius, is an empirical constant, =0.2~0.5, is the volume dilution factor, is the aging factor, is the initial number of microbubbles per unit volume, is the pressure gradient correction factor, is the gas surface energy related constant, =0.05~0.3, is the pressure change.

[0009] In some embodiments of the present invention, in step S2.3, the step of comparing the average actual radius of the microbubbles with the average theoretical radius of the microbubbles and dynamically adjusting the pulse gas delivery parameters and / or the environmental parameters until the average actual radius of the microbubbles is within the expected microbubble radius distribution range includes: If the average value of the actual radius of the microbubbles is greater than the average value of the theoretical radius of the microbubbles, at least one of the following steps is performed: increasing the stirring speed to 800-1000 rpm and maintaining it for 5-10 seconds, reducing the temperature in the environmental parameters by 1-2°C, shortening the single pulse duration of the pulse gas transmission parameters to 30-50 ms, and increasing the environmental pressure by 0.02-0.05 bar; If the average value of the actual radius of the microbubbles is less than the average value of the theoretical radius of the microbubbles, at least one of the following steps is performed: reducing the stirring speed to 200-400 rpm and maintaining it for 10-30 s, increasing the temperature in the environmental parameters by 1-2°C, extending the single pulse duration of the pulse gas transmission parameters to 150-200 ms, and reducing the environmental pressure by 0.02-0.05 bar.

[0010] In some embodiments of the present invention, the curing device is provided with an acoustic field transmitter, and the step S3 comprises: S3.1. Slowly inject the mixture into a curing device with temperature and pressure control functions, let it stand for 8 to 10 minutes, adjust it to a low pressure environment and heat it; S3.2, heating for 8-10 hours to make the ambient temperature reach 30-35°C, setting the acoustic field parameters and obtaining the real-time parameters of the microbubbles, calculating the average value of the actual radius of the microbubbles, and dynamically adjusting the acoustic field parameters to maintain the average value of the actual radius of the microbubbles within the expected microbubble radius distribution range, wherein the acoustic field parameters include the acoustic field frequency and the acoustic field intensity; S3.3, heating to 35-40°C and maintaining for 10-17 hours, intermittently opening the sound field, and dynamically adjusting the ambient pressure to maintain the average value of the actual radius of the microbubbles within the expected microbubble radius distribution range; S3.4. After curing is completed, the temperature is slowly lowered to room temperature and the pressure is returned to a state close to atmospheric pressure to obtain an ultra-high pore density polyurethane material.

[0011] In some embodiments of the present invention, in step S3.2, the step of dynamically adjusting the sound field parameters to maintain the average value of the actual radius of the microbubbles within the expected microbubble radius distribution range includes: If the average value of the actual radius of the microbubbles is less than the minimum value of the expected microbubble radius distribution range, the sound field frequency is reduced by 1 to 2 kHz, and / or the sound field intensity is reduced by 5 to 10%; If the average value of the actual radius of the microbubbles is greater than the maximum value of the expected microbubble radius distribution range, the sound field frequency is increased by 1 to 2 kHz, and / or the sound field intensity is increased by 5 to 10%.

[0012] In some embodiments of the present invention, in step S3.3, the step of dynamically adjusting the ambient pressure to maintain the average value of the actual radius of the microbubbles within the expected microbubble radius distribution range includes: If the average value of the actual radius of the microbubbles is less than the minimum value of the expected microbubble radius distribution range, reducing the ambient pressure by 0.05-0.1 bar; If the average value of the actual radius of the microbubbles is greater than the maximum value of the expected microbubble radius distribution range, the ambient pressure is increased by 0.05-0.1 bar.

[0013] The present invention provides an ultra-high pore density polyurethane material, which is prepared by the preparation method of the ultra-high pore density polyurethane material as described above, wherein the ultra-high pore density polyurethane material comprises a precursor component and a functional chain extension component, wherein the precursor component comprises a polyol group, a surfactant, a catalyst and a functional regulator, wherein the functional chain extension component comprises a multifunctional isocyanate and a viscosity diluent, wherein the polyol group comprises at least one of a trifunctional polyether polyol, a polycarbonate polyol, a polycaprolactone polyol and a polytetramethylene ether glycol, wherein the surfactant comprises an organosilicon surfactant, a polysiloxane-polyether copolymer and an aliphatic polyether surfactant. The catalyst comprises at least one of triethylenediamine, dimethylaminoethanol, dibutyltin dilaurate, and bis-(dimethylaminoethyl) ether; the functional regulator comprises at least one of organosilicon nanoparticles, tris(2-chloropropyl) phosphate, nano-montmorillonite, 1-chloro-3,3,3-trifluoropropylene, and trans-1,3,3,3-tetrafluoropropylene; the multifunctional isocyanate comprises at least one of polymerized polymethylene polyphenyl polyisocyanate, modified diphenylmethane diisocyanate, and aliphatic trimer isocyanate; and the viscosity diluent comprises at least one of lactide, γ-butyrolactone, and diethylene glycol methyl ether.

[0014] Compared with the prior art, the ultra-high pore density polyurethane material and the preparation method thereof in the present invention have the following beneficial effects: Inert gas is injected through periodic pulses to avoid excessive or uneven bubble size caused by continuous flow of gas. Pulse parameters are adjusted to achieve dynamic control of the microbubble generation process. During the gas injection process, the distribution and radius of microbubbles are monitored in real time through sensors, and the average radius is controlled within the range of 30~80μm to ensure the uniformity of bubble distribution, accurately control bubble generation and size, avoid large bubbles or uneven size distribution, and thus significantly improve the uniformity of porosity. In the gas injection stage, pulse gas injection is used to separate the bubble generation time to reduce the chance of merging between bubbles. In the curing stage, low-pressure environment and long-term curing are used to prevent bubbles from bursting due to rapid curing, increase the number of microbubbles per unit volume, and significantly improve the porosity of polyurethane materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic flow chart of the method for preparing the ultra-high pore density polyurethane material of Example 1 of the present invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] The present invention provides a method for preparing an ultra-high pore density polyurethane material, the steps comprising: S1. Prepare a precursor component and a functional chain extension component respectively, wherein the precursor component includes a polyol group, a surfactant, a catalyst and a functional regulator, and the functional chain extension component includes a multifunctional isocyanate and a viscosity diluent.

[0018] The polyol group includes at least one of trifunctional polyether polyol, polycarbonate polyol, polycaprolactone polyol and polytetramethylene ether glycol; the surfactant includes at least one of silicone surfactant, polysiloxane-polyether copolymer and aliphatic polyether surfactant; the catalyst includes at least one of triethylenediamine, dimethylaminoethanol, dibutyltin dilaurate and bis-(dimethylaminoethyl) ether; the functional regulator includes at least one of silicone nanoparticles, tris(2-chloropropyl) phosphate, nano-montmorillonite, 1-chloro-3,3,3-trifluoropropylene and trans-1,3,3,3-tetrafluoropropylene; the multifunctional isocyanate includes at least one of polymerized polymethylene polyphenyl polyisocyanate, modified diphenylmethane diisocyanate and aliphatic trimer isocyanate; and the viscosity diluent includes at least one of lactide, γ-butyrolactone and diethylene glycol methyl ether.

[0019] As the main skeleton of polyurethane materials, the polyol group provides flexibility, mechanical strength and chemical stability of the molecular chain. The cross-linking density is increased by introducing trifunctional polyether polyols, thereby improving the mechanical properties and heat resistance of the material. Polycarbonate polyols provide excellent hydrolysis resistance and chemical corrosion resistance, making the material suitable for harsh environments. Polycaprolactone polyols give the material higher flexibility and ductility while improving wear resistance. Polytetramethylene ether glycol improves the material's elasticity and low-temperature resistance, making it suitable for scenarios that require elastic recovery properties.

[0020] Surfactants reduce the interfacial tension of bubbles and promote the uniform dispersion and stability of microbubbles. Silicone surfactants significantly reduce the surface tension of the mixed system through their unique silicon-oxygen chain structure, ensuring uniform microbubble size. Polysiloxane-polyether copolymers combine the hydrophobicity of silicon-oxygen chains and the hydrophilicity of polyethers, enhancing the stability of bubbles and preventing collapse. Aliphatic polyether surfactants provide additional foam stabilization effects and improve the uniformity of pore distribution.

[0021] Catalysts accelerate the reaction of polyols and isocyanates, ensuring the reaction efficiency and stability of material properties. Triethylenediamine efficiently promotes the reaction rate of isocyanate groups and polyol groups, reducing the reaction time. Dimethylaminoethanol controls the crosslinking rate to avoid premature curing during the foaming process and ensure the uniformity of the pore structure. Dibutyltin dilaurate provides stable catalytic activity and improves the mechanical properties of polyurethane. Bis-(dimethylaminoethyl) ether controls the rate of bubble generation and expansion in the system, improving the size controllability of microbubbles.

[0022] Functional regulators adjust the porosity, weatherability and stability of the material. Silicone nanoparticles increase the hydrophobicity and durability of the material surface and further stabilize the microbubbles. Tris(2-chloropropyl) phosphate improves the flame retardancy of the material and is suitable for applications that require fire resistance. Nano-montmorillonite improves the mechanical properties of the material through a layered structure and enhances the strength of the microbubble wall. 1-Chloro-3,3,3-trifluoropropene and trans-1,3,3,3-tetrafluoropropene reduce the free energy of the material surface and improve the dispersion and uniformity of the pores.

[0023] Multifunctional isocyanates act as crosslinkers to react with polyol groups to form the backbone structure of the polyurethane chain. Polymeric polymethylene polyphenyl polyisocyanates provide higher crosslinking density and excellent mechanical properties. Modified diphenylmethane diisocyanate improves its reactivity with polyols through modification and improves the uniformity of the pore structure. Aliphatic trimer isocyanates give the material better weather resistance and avoid performance degradation under ultraviolet and high temperature environments.

[0024] Viscosity diluents reduce the viscosity of the system and improve the processing performance of the material during the preparation process. Lactide and γ-butyrolactone reduce the viscosity of the reaction system, promote uniform mixing of components, and help form a more uniform pore distribution. Diethylene glycol methyl ether enhances the lubricity of the system, improves the stability of bubbles and the processing efficiency of the material.

[0025] In summary, by carefully selecting and combining the above raw materials, the following technical effects are achieved: pore uniformity and stability, through the synergistic effect of surfactants and functional regulators, the stability and uniformity of bubbles are significantly improved, and the pore structure is ensured not to collapse or merge during the preparation and curing process. The optimization of the mechanical properties of the material, the scientific selection and matching of polyol groups and isocyanates give the material excellent mechanical strength, flexibility and weather resistance. The pore structure is precisely controlled, and the precise size control of microbubbles (30~80μm) is achieved through the auxiliary effect of functional regulators and viscosity diluents, the pore density is increased and the controllability of the structure is ensured. It is suitable for a variety of application scenarios, including high temperature, humid, corrosive environments (due to the use of polycarbonate polyols, nano-montmorillonite, etc.), and scenarios with high fire resistance requirements (due to the addition of phosphate regulators). Improve the processability of the material, the viscosity diluent reduces the viscosity of the system, and the surfactant and catalyst improve the mixing performance, making the preparation process more efficient.

[0026] S1.1. First, place a polyol group in a stirred reactor, slowly heat it to 23-25°C, for example, 23°C, 24°C, and 25°C, and continue to introduce an inert gas, and at the same time, sequentially add a surfactant, a catalyst, and a functional regulator and stir for 10-15 minutes, for example, 10 minutes, 13 minutes, and 15 minutes, to obtain a precursor component, wherein the stirring speed is 300-500 rpm, for example, 300 rpm, 400 rpm, and 500 rpm. In the precursor component, calculated by mass percentage, the surfactant accounts for 1-3%, for example, 1%, 2%, and 3%, the catalyst accounts for 0.5-1%, for example, 0.5%, 0.8%, and 1%, the functional regulator accounts for 0.5-2%, for example, 0.5%, 1%, and 2%, and the balance is the polyol group.

[0027] Provide a suitable viscosity environment for the full mixing of the precursor components to avoid volatilization of components or premature initiation of chemical reactions due to excessive temperature. Ensure that the polyol groups, surfactants, catalysts and functional regulators in the precursor components are evenly dispersed to form a stable liquid phase system. Avoid local component enrichment or unevenness to provide a stable base environment for the subsequent generation of microbubbles.

[0028] The introduction of inert gas prevents oxidation or other adverse reactions from occurring, while reducing the surface tension of the liquid, laying the foundation for the formation of stable and uniform microbubbles when the bubbles are subsequently injected. The uniformly dispersed surfactants and functional regulators provide an ideal environment for the formation of stable microbubbles when the inert gas is subsequently injected. By adjusting the component ratio and distribution of the precursor components, the size of the microbubbles (30~80μm) and the uniformity of their distribution can be effectively controlled.

[0029] Through the flexibility of precursor component preparation, in scenarios such as heat insulation, sound absorption, filtration, load bearing, etc., by adjusting the proportion of precursor components and preparation conditions, pore structures and mechanical properties for different performance requirements can be achieved. Stable precursor components can adapt to subsequent high-speed shearing, gas injection and curing steps, ensuring the smoothness of the overall preparation process and avoiding adverse reactions caused by unstable precursor components.

[0030] In one embodiment, step S1 includes: S1.2, add the multifunctional isocyanate to another chamber of the stirred reactor, heat to 20-22°C, for example, 20°C, 21°C, 22°C, and stir for 2-5min, for example, 2min, 3min, 5min, then add the viscosity diluent, and continue stirring for 5-10min, for example, 5min, 8min, 10min, to obtain a functional chain extension component, wherein the stirring speed is 100-200rpm, for example, 100rpm, 150rpm, 200rpm, and in the functional chain extension component, the mass ratio of the multifunctional isocyanate to the viscosity diluent is 10-12:1, for example, 10:1, 11:1, 12:1.

[0031] Keep the multifunctional isocyanate and viscosity diluent fully mixed to ensure uniform viscosity, so that it can be quickly dispersed when the precursor components are added later. A lower stirring speed can reduce the foam formation of the isocyanate and avoid affecting the rheological properties of the system. Preliminary mixing (stirring for 2~5min) is used to achieve uniform pre-dispersion of the isocyanate, and re-mixing (stirring for 5~10min) ensures that the viscosity diluent and isocyanate are fully and evenly dispersed to form a chain extension component with good fluidity.

[0032] Isocyanate and viscosity diluent have low reactivity at low temperatures, which can avoid premature reaction of isocyanate due to local overheating, help maintain the chemical stability of isocyanate and reduce the occurrence of side reactions. Fully uniform chain extension components can react quickly with precursor components during subsequent high-speed shear mixing, reducing the deviation of microbubble size distribution. Precise component ratio and uniformity ensure the strength of microbubble walls and reduce the probability of pore collapse or merging.

[0033] Isocyanate groups (-NCO) are sensitive to moisture and temperature. High temperatures may lead to premature reactions or side reactions (such as reaction with moisture to produce carbon dioxide), which may affect the performance of the material. 20~22℃ is the optimal temperature for mixing isocyanates with viscosity diluents, which can ensure uniformity of components and inhibit side reactions. Multifunctional isocyanates and certain diluents may volatilize at high temperatures. Low-temperature operation can reduce volatilization losses and ensure the accuracy of component ratios. At lower temperatures, the chain extension reaction is less active, which helps to gradually react in the subsequent mixing stage and avoid curing due to excessive reactions in the preparation stage of the chain extension components.

[0034] S2. Inject inert gas into the precursor component in a periodic pulse manner to form microbubbles, and monitor the bubble distribution parameters in real time during the gas injection process to control the average diameter of the microbubbles within 30-80 μm, for example, 30 μm, 40 μm, 80 μm. In this state, add the functional chain extension component and mix it at a high speed to obtain a mixture, so that the microbubbles can be stably dispersed and directional arranged in the mixture.

[0035] By periodically injecting inert gas in pulses, the generation rate and size distribution of microbubbles can be precisely controlled to keep their average diameter within the target range of 30-80 μm. This ensures the uniformity and stability of the pores and improves the thermal insulation, sound absorption and other properties of the material. In high-speed shear mixing, microbubbles are not easy to merge or collapse due to their uniform size and stable distribution, ensuring the stability and functionality of the pore structure. High-speed shearing can make the microbubbles disperse evenly in the mixture, while forming a certain directional arrangement along the mixing direction, optimizing the isotropic properties of the material.

[0036] Periodic pulse injection releases inert gas periodically through the gas delivery device, so that the gas is injected into the precursor component in the form of pulses. Its implementation method includes the following key parameters: Pulse frequency, which indicates the number of pulse injections per unit time, ranges from 0.5 to 2 Hz (i.e., 0.5 to 2 pulses per second). Higher frequencies are suitable for generating small bubbles, while lower frequencies are suitable for generating large bubbles. Single pulse duration, the duration of each gas injection. Ranges from 30 to 200 ms. Short pulses (30 to 50 ms) are used to generate small bubbles (with a diameter close to 30 μm), and long pulses (150 to 200 ms) are used to generate large bubbles (with a diameter close to 80 μm). Injection pressure, the pressure of the injected inert gas, ranges from 0.1 to 0.5 bar. Lower pressures (0.1 to 0.2 bar) generate smaller bubbles, while higher pressures (0.3 to 0.5 bar) promote rapid bubble generation and increase in size.

[0037] In the present application, a multi-stage pulse gas transmission module and a control unit are provided inside the stirred reactor. The multi-stage pulse gas transmission module includes a sensor, a gas transmission device, and a data acquisition interface connected to the control unit signal. The gas transmission device is used to realize periodic pulse gas injection. An optical sensor or a laser particle size analyzer can be used inside the stirred reactor to monitor the bubble size distribution, and the pulse frequency, duration or injection pressure can be dynamically adjusted to ensure that the bubble size is evenly distributed within the range of 30 to 80 μm. The specific structure and use principle of all sensors, devices and equipment inside the stirred reactor are well known to those skilled in the art and will not be repeated here.

[0038] In one embodiment, step S2 includes: S2.1. Set the pulse gas transmission parameters and environmental parameters according to the target porosity and the expected microbubble radius distribution range. The expected microbubble radius distribution can be 30~80μm, or it can be set according to actual production. Environmental parameters may include stirring speed, stirring temperature and pressure. A higher stirring speed can reduce the microbubble radius, while a lower stirring speed can reduce the microbubble radius. A higher temperature reduces the viscosity of the liquid, which helps bubble generation and expansion. A lower temperature improves bubble stability and reduces bubble breakage or merging. Increasing the environmental pressure can compress the bubble size and reduce the porosity. Reducing the environmental pressure is conducive to bubble expansion and an increase in porosity.

[0039] S2.2. Inject inert gas into the precursor component according to the pulse gas transmission parameters and obtain real-time parameters of microbubbles, and start stirring. The stirring speed is 300-500 rpm, for example, 300 rpm, 400 rpm, or 500 rpm.

[0040] Real-time parameters of microbubbles may include the following parameters: Microbubble radius, used to evaluate whether the microbubble size meets the expected microbubble radius distribution range. Monitoring method: Laser particle size analyzer, which calculates the diameter by measuring the scattering intensity of the microbubble to the laser. Optical microscope combined with image processing, real-time image acquisition and analysis of the microbubble boundary to obtain the radius. Microbubble number density, the number of microbubbles contained in a unit volume of liquid.

[0041] Monitoring method: resistance pulse method, the resistance change when bubbles pass through microchannels can be used to calculate the number density. Fluid imaging technology, capturing the number of bubbles per unit volume through images.

[0042] S2.3. Obtain the average actual radius of microbubbles and calculate the average theoretical radius of microbubbles through real-time parameters of microbubbles and environmental parameters, compare the average actual radius of microbubbles with the average theoretical radius of microbubbles, and dynamically adjust the pulse gas delivery parameters and / or environmental parameters until the average actual radius of microbubbles is within the expected microbubble radius distribution range.

[0043] During the foaming process, the bubble size is prone to large fluctuations due to uneven generation conditions (such as gas injection and stirring speed) and environmental conditions (such as temperature and pressure), resulting in uneven distribution of bubble size and affecting the performance of the final material.

[0044] The average value of the actual radius of the microbubbles is obtained through an optical microscope combined with image processing or other monitoring methods such as a laser particle size analyzer; the average value of the theoretical radius of the microbubbles is a reference value calculated based on the real-time parameters of the microbubbles and environmental parameters. During the stirring process of the precursor components, this reference value is used to determine the direction of the microbubble size deviation, and to correct the deviation by adjusting the pulse gas transmission parameters (such as single pulse duration and frequency) and / or environmental parameters (such as temperature and pressure) to make the microbubble size distribution uniform, avoid the generation of large bubbles or too small bubbles, and automatically adjust the system to avoid errors caused by manual intervention, improve the controllability of bubble size and porosity in the production process, and achieve consistency in the performance of different batches of materials.

[0045] In step S2.3, the calculation formula for the average value of the theoretical radius of microbubbles is: in, is the real-time theoretical radius average value, The preset porosity indicates the theoretical porosity after the precursor components are stirred. The calculation formula is: ; is the real-time number of microbubbles per unit volume, is the average theoretical volume of microbubbles, is the correction factor to take into account the non-uniformity of microbubble distribution, is the standard deviation of the microbubble radius, is an empirical constant, =0.2~0.5, is the volume dilution factor, is the aging factor, is the initial number of microbubbles per unit volume, which is the initial number of microbubbles in the prepared precursor component. is the pressure gradient correction factor, is the gas surface energy related constant, =0.05~0.3, is the pressure change.

[0046] Correction factors in the above parameters , Pressure gradient correction factor , volume dilution factor , aging factors They are all affected by the pulse gas delivery parameters and environmental parameters, which can guide the dynamic adjustment of the pulse gas delivery parameters and environmental parameters to change the average value of the real-time radius of microbubbles.

[0047] Correction Factor The standard deviation of the microbubble radius in the calculation formula It is obtained through statistics of multiple preliminary experiments, and the deviation of the microbubble radius is monitored through multiple repeated experiments. and Positively correlated, Affected by stirring speed. Because, the higher the stirring speed, the greater the shear force in the liquid, and high shear force helps to split larger bubbles into smaller bubbles, thereby reducing the standard deviation of the microbubble radius. , reducing the uneven distribution problem caused by the presence of large bubbles. The lower the stirring speed, the lower the shear force. The shearing effect of low shear force is insufficient, the bubbles are difficult to split, and large bubbles are easily formed. The standard deviation of the microbubble radius . Moreover, the stirring speed determines the turbulence intensity of the mixed liquid. High turbulence intensity enhances the dispersion of gas in the liquid, homogenizes the microbubble generation process, reduces the collision and merger between bubbles of different sizes, and thus reduces the discreteness (i.e., standard deviation) of microbubble size. When the turbulence intensity is low, the gas distribution is uneven, and larger bubbles may form in some areas, while smaller bubbles form in other areas, which increases the standard deviation of the microbubble radius. .

[0048] Pressure gradient correction factor Pressure change Positive correlation, Indicates the difference between the real-time pressure of the environment and the initial pressure, that is, the pressure is increased. Increase, Increase, Increases, the real-time theoretical radius average When the pressure decreases, it is used to guide how to reduce the actual average radius. When the pressure decreases, it is used to guide how to increase the actual average radius.

[0049] Volume dilution factor Indicates how the volume of gas injected per unit time is dispersed or diluted by the liquid. Volume dilution factor Affected by the pulse gas transmission parameters, the longer the single pulse duration in the pulse gas transmission parameters, the greater the total amount of gas injected, which is prone to insufficient mixing and difficulty in gas diffusion, resulting in Reduce, and then Reduced, the real-time theoretical radius average The shorter the single pulse duration in the pulse gas transmission parameters is, the more moderate the gas injection volume is, and the easier it is for the gas to be evenly dispersed in the liquid. Improve, and then Increase, the real-time theoretical radius average It is used to guide how to reduce the actual radius average value.

[0050] Aging Factors It indicates the degree of attenuation of the number of microbubbles over time during their life cycle after they are generated. It describes the process of gradual reduction of microbubbles due to dynamic behaviors such as rupture, merging, diffusion and dissolution. Temperature affects the solubility of gas and the surface tension of bubbles. High-temperature gas dissolves faster, and microbubbles are prone to shrink or disappear. , Reduced, the real-time theoretical radius average It is used to guide how to increase the actual radius average. Low temperature slows down the gas diffusion rate, increases the stability of microbubbles, and increases , Increase, the real-time theoretical radius average It is used to guide how to reduce the actual radius average value.

[0051] According to the influence of the above parameters on the actual radius average, in step S2.3, the actual radius average of the microbubbles is compared with the theoretical radius average of the microbubbles, and the pulse gas delivery parameters and / or environmental parameters are dynamically adjusted until the actual radius average of the microbubbles is within the expected microbubble radius distribution range. The steps include: If the average actual radius of the microbubbles is greater than the average theoretical radius of the microbubbles, the stirring speed is increased to 800-1000 rpm, such as 800 rpm, 900 rpm, 1000 rpm, and maintained for 5-10 s, such as 5 s, 8 s, 10 s.

[0052] and / or, lowering the temperature in the environmental parameters by 1-2°C, for example, 1°C, 1.5°C, or 2°C; and / or, shortening the single pulse duration of the pulse gas transmission parameter to 30-50 ms, for example, 30 ms, 40 ms, or 50 ms; and / or, increasing the ambient pressure by 0.02-0.05 bar, for example, 0.02 bar, 0.03 bar, 0.05 bar; And / or, introduce surfactants or polyol groups into the precursor components. The core role of surfactants is to optimize the bubble generation process and increase the life of bubbles by regulating the bubble interfacial tension and interfacial stability. Surfactant molecules are adsorbed on the bubble-liquid interface, significantly reducing the interfacial tension and the probability of bubble rupture. The interfacial film formed by the surfactant has a certain mechanical strength and adhesion, which can resist external shear force, turbulence and collision between bubbles to prevent bubble rupture or merging. The liquid film formed by the surfactant between bubbles increases the repulsive force between bubbles (such as electrostatic repulsion or steric exclusion), thereby reducing the probability of bubble merging. Therefore, the introduction of surfactants can improve the aging factor. , providing guidance on how to improve the average value of the actual radius. That is, when the average value of the actual radius of the microbubbles is greater than the average value of the theoretical radius of the microbubbles, any one or all other permutations and combinations of the above four steps are performed.

[0053] If the average actual radius of the microbubbles is less than the average theoretical radius of the microbubbles, the stirring speed is reduced to 200-400 rpm, for example, 200 rpm, 300 rpm, 400 rpm, and maintained for 10-30 s, for example, 10 s, 18 s, 30 s; and / or, raising the temperature in the environmental parameters by 1-2°C, for example, 1°C, 1.5°C, or 2°C; And / or, the single pulse duration of the pulse gas transmission parameter is extended to 150-200 ms, for example, 150 ms, 180 ms, or 200 ms.

[0054] That is, when the average value of the actual radius of the microbubbles is less than the average value of the theoretical radius of the microbubbles, any one or all other permutations and combinations of the above three steps are performed.

[0055] S2.4, slowly add the functional chain extension component to the precursor component, maintain the stirring speed at 500~600 rpm, for example, it can be 500rpm, 550rpm, 600rpm. After the functional chain extension component is added, increase the stirring rate to 1000~1500rpm, for example, it can be 1000rpm, 1100rpm, 1200rpm, and maintain it for 10~30s, for example, it can be 10s, 20s, 30s.

[0056] In the stage of slowly adding functional chain extension components, low-speed stirring can avoid microbubble rupture or over-dispersion caused by excessive shear force. Ensure that the functional chain extension components are gradually mixed with the precursor components while maintaining uniform distribution of bubbles. Avoid uneven size and premature rupture of microbubbles, and improve the porosity and uniformity of bubble distribution of the final material.

[0057] After the functional chain extension components are fully added, high-speed stirring can provide strong shear force to quickly and evenly mix the precursor components and the functional chain extension components. Effectively disperse potential large bubbles and break them into smaller microbubbles, further optimizing the pore structure. Improve the uniformity of microbubble distribution, prevent local areas from collapsing due to excessive bubbles, and ensure the mechanical properties of the material.

[0058] S2.5. Determine whether the average value of the actual radius of the microbubbles is maintained within the expected microbubble radius distribution range. If so, reduce the stirring to 500-600 rpm, such as 500 rpm, 550 rpm, and 600 rpm, and maintain for 1-2 min, such as 1 min, 1.5 min, and 2 min, to obtain a mixture. If not, continue stirring until the average value of the actual radius of the microbubbles is within the expected microbubble radius distribution range.

[0059] By real-time detection of the average value of the actual radius of microbubbles and comparing it with the expected range (e.g., 30-80 µm), abnormal size distribution can be discovered in time and adjusted to ensure the uniformity of microbubbles. If the size exceeds the target range, continued stirring can break up large bubbles to prevent them from affecting the overall distribution. For small bubbles, appropriately extending the stirring time or adjusting the parameters can promote their merging and moderate expansion. Ensure that the size of microbubbles is within the target distribution range and reduce abnormally large or small bubbles. The uniform distribution of microbubble size directly determines the consistency of the porosity and mechanical properties of the material. If large bubbles are not broken up in time, the porosity distribution of the material may be uneven, affecting the performance. By continuing to stir, the average radius of the bubbles can be reduced, large bubbles can be prevented from forming, and the distribution can be optimized. Small bubbles may cause local density to increase, reducing the thermal insulation or sound absorption performance of the material. Prolonging the stirring time appropriately will help the stable expansion of small bubbles and make the bubble size uniform.

[0060] S3. Inject the mixture into a curing device with temperature and pressure control functions to obtain an ultra-high pore density polyurethane material after curing, wherein the curing temperature is 30-40°C, for example, 30°C, 35°C, 40°C, and the curing time is 20-25h, for example, 20h, 23h, 25h.

[0061] By controlling the temperature and time, the distribution and size of microbubbles are optimized to ensure that the material has high porosity and a stable porous structure. The integrity of the cross-linked network of the material is achieved, and the compressive and tensile strengths are improved. The uniform distribution of microbubbles and stable porosity significantly improve the thermal insulation and sound absorption functions of the material. The bubble rupture, collapse and material deformation are effectively controlled to ensure the stability and consistency of the finished product.

[0062] In one embodiment, a sound field transmitter is provided in the curing device. The sound field is a non-contact dynamic control method that can directly affect the vibration, stability and distribution of bubbles through the action of sound waves, improve the uniformity of microbubble size distribution, reduce size variance, and prevent the generation of large bubbles and bubble rupture.

[0063] Step S3 includes: S3.1. Slowly inject the mixture into a curing device with temperature and pressure control functions. After standing for 8 to 10 minutes, adjust to a low pressure environment and heat.

[0064] Let the mixture stand to stabilize the microbubbles in it, reduce the possibility of initial bubble rupture or merging, ensure a more uniform distribution of microbubbles in the mixture, and provide good initial conditions for subsequent curing.

[0065] Low pressure helps expand microbubbles, optimizes pore structure, reduces the risk of bubble collapse, and increases material porosity. The air pressure range of low pressure environment can be 0.1~0.5 bar. When selecting a specific air pressure, it can be dynamically adjusted according to the viscosity of the mixture, the size distribution and stability of the microbubbles.

[0066] S3.2, heating for 8 to 10 hours, for example, 8 hours, 9 hours, 10 hours, to make the ambient temperature reach 30 to 35 degrees Celsius, for example, 30 degrees Celsius, 34 degrees Celsius, 35 degrees Celsius, setting the sound field parameters and obtaining the real-time parameters of the microbubbles, calculating the average value of the actual radius of the microbubbles, and dynamically adjusting the sound field parameters to maintain the average value of the actual radius of the microbubbles within the expected microbubble radius distribution range, wherein the sound field parameters include the sound field frequency and the sound field intensity.

[0067] Changes in the frequency of the acoustic field can control the vibration amplitude and resonance behavior of microbubbles. Higher frequencies (such as 40~60kHz) are suitable for stabilizing smaller bubbles and helping to break up large bubbles, while lower frequencies (such as 20~40 kHz) are suitable for promoting the expansion and uniform distribution of bubbles.

[0068] Adjusting the intensity of the sound field can further control the effect of sound waves on bubbles. Higher intensity can enhance the vibration intensity of the bubble interface to prevent bubble rupture, while lower intensity can prevent excessive vibration from causing nonlinear behavior of bubbles during the expansion stage. The change of bubble radius can be obtained in real time, and the sound field can be adjusted dynamically to ensure that the average radius of microbubbles is maintained within the desired range.

[0069] S3.3. Heating to 35-40°C, for example, 35°C, 38°C, 40°C, and maintaining for 10-17h, for example, 10h, 15h, 17h, the sound field is intermittently turned on, and the ambient pressure is dynamically adjusted to maintain the average value of the actual radius of the microbubbles within the expected microbubble radius distribution range.

[0070] The intermittent sound field can reduce the negative impact of the continuous sound field on the stability of microbubbles, reduce the risk of bubble rupture, optimize the microbubble structure through intermittent excitation, and further reduce the discreteness of the microbubble size.

[0071] The effect of dynamically adjusting the ambient pressure is the same as in step S2, but in the mixing stage of S2, the viscosity of the mixture is lower, and the bubbles are more sensitive to pressure changes. Slight pressure fluctuations can significantly affect the generation and distribution of microbubbles, and no large adjustments are required. In the curing stage of S3, the size distribution of the microbubbles is locked and the pore structure is optimized, while improving the overall performance and stability of the material. The viscosity of the mixture during the curing stage is higher, and the sensitivity of the microbubbles to pressure is reduced, requiring a larger pressure adjustment range to significantly affect the size changes of the bubbles. Larger pressure changes can help microbubbles expand or compress in high-viscosity environments while preventing material structural defects. The dual control method of combining acoustic field and pressure regulation ensures that the bubble distribution is within the desired range and improves the quality and stability of the material's pore structure.

[0072] S3.4. After curing, slowly cool down to room temperature and return the pressure to near atmospheric pressure to obtain ultra-high pore density polyurethane material. Slow cooling reduces the internal stress caused by rapid cooling, prevents material cracking or deformation, and ensures that the pore structure does not change significantly during the curing process. Gradually restore the pressure to atmospheric pressure to avoid damage to the bubble structure due to sudden pressure changes.

[0073] In step S3.2, the step of dynamically adjusting the sound field parameters to maintain the average value of the actual radius of the microbubbles within the expected microbubble radius distribution range includes: If the average value of the actual radius of the microbubbles is less than the minimum value of the expected microbubble radius distribution range, the sound field frequency is reduced by 1-2 kHz, for example, 1 kHz, 1.5 kHz, 2 kHz, and / or the sound field intensity is reduced by 5-10%, for example, 5%, 8%, 10%. That is, when the average value of the actual radius of the microbubbles is less than the minimum value of the expected microbubble radius distribution range, any one of the above two steps or both are performed.

[0074] If the average value of the actual radius of the microbubbles is greater than the maximum value of the expected microbubble radius distribution range, the sound field frequency is increased by 1 to 2 kHz, for example, 1 kHz, 1.5 kHz, 2 kHz, and / or the sound field intensity is increased by 5 to 10%, for example, 5%, 8%, 10%. That is, when the average value of the actual radius of the microbubbles is greater than the maximum value of the expected microbubble radius distribution range, any one of the above two steps or both are performed.

[0075] In step S3.3, the step of dynamically adjusting the ambient pressure to maintain the average value of the actual radius of the microbubbles within the expected microbubble radius distribution range includes: If the average value of the actual radius of the microbubbles is less than the minimum value of the expected microbubble radius distribution range, the ambient pressure is reduced by 0.05-0.1 bar, for example, 0.05 bar, 0.08 bar, or 0.1 bar; If the average value of the actual radius of the microbubbles is greater than the maximum value of the expected microbubble radius distribution range, the ambient pressure is increased by 0.05-0.1 bar, for example, 0.05 bar, 0.08 bar, or 0.1 bar.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an ultra-high pore density polyurethane material, characterized in that the steps include: S1. Preparing a precursor component and a functional chain extension component respectively, wherein the precursor component comprises a polyol group, a surfactant, a catalyst and a functional regulator, and the functional chain extension component comprises a multifunctional isocyanate and a viscosity diluent; S2, injecting an inert gas into the precursor component in a periodic pulse manner to form microbubbles, and monitoring the bubble distribution parameters in real time during the gas injection process, controlling the average radius of the microbubbles within 30-80 μm, adding the functional chain extension component in this state and mixing at a high speed to obtain a mixture, so that the microbubbles are stably dispersed and oriented in the mixture; S3. Injecting the mixture into a curing device with temperature and pressure control functions, and obtaining an ultra-high pore density polyurethane material after curing, wherein the curing temperature is 30-40° C. and the curing time is 20-25 hours.

2. The method for preparing the ultra-high pore density polyurethane material according to claim 1, characterized in that: The step S1 comprises: S1.

1. First, place a polyol group in a stirred reactor, slowly heat it to 23-25°C and continuously introduce an inert gas, and simultaneously dropwise add a surfactant, a catalyst and a functional regulator and stir for 10-15 minutes to obtain a precursor component, wherein the stirring speed is 300-500 rpm, and in the precursor component, calculated by mass percentage, the surfactant accounts for 1-3%, the catalyst accounts for 0.5-1%, the functional regulator accounts for 0.5-2%, and the remainder is the polyol group; S1.2, adding the multifunctional isocyanate to another chamber of the stirred reactor, heating to 20-22°C and stirring for 2-5 minutes, then adding the viscosity diluent, and continuing to stir for 5-10 minutes to obtain a functional chain extension component, wherein the stirring speed is 100-200 rpm, and in the functional chain extension component, the mass ratio of the multifunctional isocyanate to the viscosity diluent is 10-12:

1.

3. The method for preparing the ultra-high pore density polyurethane material according to claim 2, characterized in that: The stirred reactor is provided with a multi-stage pulse gas transmission module and a control unit, wherein the multi-stage pulse gas transmission module includes a sensor, a gas transmission device and a data acquisition interface connected to the control unit by signal. Step S2 includes: S2.

1. Set pulse gas transmission parameters and environmental parameters according to the target porosity and expected microbubble radius distribution range; S2.2, injecting inert gas into the precursor component according to the pulse gas transmission parameters and obtaining real-time parameters of microbubbles, and starting stirring at a stirring speed of 300-500 rpm; S2.3, obtaining the average value of the actual radius of microbubbles and calculating the average value of the theoretical radius of microbubbles through the real-time parameters of the microbubbles and the environmental parameters, comparing the average value of the actual radius of microbubbles with the average value of the theoretical radius of microbubbles, and dynamically adjusting the pulse gas delivery parameters and / or the environmental parameters until the average value of the actual radius of microbubbles is within the expected microbubble radius distribution range; S2.4, slowly adding the functional chain extension component to the precursor component, maintaining a stirring speed of 500-600 rpm, and after the functional chain extension component is added, increasing the stirring rate to 1000-1500 rpm and maintaining for 10-30s; S2.

5. Determine whether the average actual radius of the microbubbles is maintained within the expected microbubble radius distribution range. If so, reduce the stirring speed to 500-600 rpm and maintain for 1-2 minutes to obtain a mixture. If not, continue stirring until the average actual radius of the microbubbles is within the expected microbubble radius distribution range.

4. The method for preparing the ultra-high pore density polyurethane material according to claim 3, characterized in that: In step S2.3, the calculation formula of the average value of the theoretical radius of microbubbles is: in, is the average theoretical radius of microbubbles, is the preset porosity, is the real-time number of microbubbles per unit volume, is the correction factor to take into account the non-uniformity of microbubble distribution, is the standard deviation of the microbubble radius, is an empirical constant, =0.2~0.5, is the volume dilution factor, is the aging factor, is the initial number of microbubbles per unit volume, is the pressure gradient correction factor, is the gas surface energy related constant, =0.05~0.3, is the pressure change.

5. The method for preparing the ultra-high pore density polyurethane material according to claim 3, characterized in that: In step S2.3, the step of comparing the average actual radius of the microbubbles with the average theoretical radius of the microbubbles and dynamically adjusting the pulse gas delivery parameters and / or the environmental parameters until the average actual radius of the microbubbles is within the expected microbubble radius distribution range includes: If the average value of the actual radius of the microbubbles is greater than the average value of the theoretical radius of the microbubbles, at least one of the following steps is performed: increasing the stirring speed to 800-1000 rpm and maintaining it for 5-10 seconds, reducing the temperature in the environmental parameters by 1-2°C, shortening the single pulse duration of the pulse gas transmission parameters to 30-50 ms, and increasing the environmental pressure by 0.02-0.05 bar; If the average value of the actual radius of the microbubbles is less than the average value of the theoretical radius of the microbubbles, at least one of the following steps is performed: reducing the stirring speed to 200-400 rpm and maintaining it for 10-30 s, increasing the temperature in the environmental parameters by 1-2°C, extending the single pulse duration of the pulse gas transmission parameters to 150-200 ms, and reducing the environmental pressure by 0.02-0.05 bar.

6. The method for preparing the ultra-high pore density polyurethane material according to claim 1, characterized in that: The curing device is provided with an acoustic field transmitter, and the step S3 comprises: S3.

1. Slowly inject the mixture into a curing device with temperature and pressure control functions, let it stand for 8 to 10 minutes, adjust it to a low pressure environment and heat it; S3.2, heating for 8-10 hours to make the ambient temperature reach 30-35°C, setting the sound field parameters and obtaining the real-time parameters of the microbubbles, calculating the average value of the actual radius of the microbubbles, and dynamically adjusting the sound field parameters to maintain the average value of the actual radius of the microbubbles within the range of 30-80 μm, wherein the sound field parameters include the sound field frequency and the sound field intensity; S3.3, heating to 35-40°C and maintaining for 10-17 hours, intermittently opening the sound field, and dynamically adjusting the ambient pressure to maintain the average value of the actual radius of the microbubbles within the expected microbubble radius distribution range; S3.

4. After curing is completed, the temperature is slowly lowered to room temperature and the pressure is returned to a state close to atmospheric pressure to obtain an ultra-high pore density polyurethane material.

7. The method for preparing the ultra-high pore density polyurethane material according to claim 6, characterized in that: In step S3.2, the step of dynamically adjusting the sound field parameters to maintain the average value of the actual radius of the microbubbles within the expected microbubble radius distribution range includes: If the average value of the actual radius of the microbubbles is less than the minimum value of the expected microbubble radius distribution range, the sound field frequency is reduced by 1 to 2 kHz, and / or the sound field intensity is reduced by 5 to 10%; If the average value of the actual radius of the microbubbles is greater than the maximum value of the expected microbubble radius distribution range, the sound field frequency is increased by 1 to 2 kHz, and / or the sound field intensity is increased by 5 to 10%.

8. The method for preparing the ultra-high pore density polyurethane material according to claim 6, characterized in that: In step S3.3, the step of dynamically adjusting the ambient pressure to maintain the average value of the actual radius of the microbubbles within the expected microbubble radius distribution range includes: If the average value of the actual radius of the microbubbles is less than the minimum value of the expected microbubble radius distribution range, reducing the ambient pressure by 0.05-0.1 bar; If the average value of the actual radius of the microbubbles is greater than the maximum value of the expected microbubble radius distribution range, the ambient pressure is increased by 0.05-0.1 bar.

9. An ultra-high pore density polyurethane material, characterized in that: The ultra-high pore density polyurethane material is prepared by the preparation method of any one of claims 1 to 8, wherein the ultra-high pore density polyurethane material comprises a precursor component and a functional chain extension component, wherein the precursor component comprises a polyol group, a surfactant, a catalyst and a functional regulator, wherein the functional chain extension component comprises a multifunctional isocyanate and a viscosity diluent, wherein the polyol group comprises at least one of trifunctional polyether polyol, polycarbonate polyol, polycaprolactone polyol and polytetramethylene ether glycol, wherein the surfactant comprises at least one of an organosilicon surfactant, a polysiloxane-polyether copolymer and an aliphatic polyether surfactant. One, the catalyst includes at least one of triethylenediamine, dimethylaminoethanol, dibutyltin dilaurate, and bis-(dimethylaminoethyl) ether; the functional regulator includes at least one of organosilicon nanoparticles, tris(2-chloropropyl) phosphate, nano-montmorillonite, 1-chloro-3,3,3-trifluoropropylene, and trans-1,3,3,3-tetrafluoropropylene; the multifunctional isocyanate includes at least one of polymerized polymethylene polyphenyl polyisocyanate, modified diphenylmethane diisocyanate, and aliphatic trimer isocyanate; and the viscosity diluent includes at least one of lactide, γ-butyrolactone, and diethylene glycol methyl ether.

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