Silicon-based polyurethane nucleating agent and preparation method thereof

Abstract

The application relates to the field of plastic additives, in particular to a silicon-based polyurethane nucleating agent and a preparation method thereof. In the application, a mesoporous silicon dioxide is prepared by adopting a one-pot boiling form of a polycondensation method, pre-polymerizing a tetraethyl orthosilicate mixture, and taking low-molecular polyamide and 4-12 carbon single-chain aliphatic double-end amine as a template agent. The mesoporous silicon dioxide has a good pore structure, is low in cost, can realize the foaming effect of polyurethane by doping 1%, and forms a polyurethane system with good strength.

Description

Technical Field

[0001] This application relates to the field of plastic additives, and in particular to a polyurethane nucleating agent and its preparation method. Background Technology

[0002] Polyurethane nucleating agents are functional additives that provide a "starting point" for bubbles in the early stages of foaming. They can significantly alter the number, size, and distribution of foam cells, thereby determining the mechanical, thermal insulation, and acoustic properties of the final product. Current research on polyurethane nucleating agents generally focuses on ordinary inorganic oxides or polypropylene nucleating agents, whose overall technical and economic indicators cannot meet market demands. Therefore, the development of polyurethane foam nucleating agents is imperative.

[0003] Available polyurethane nucleating agents typically include several types such as organosilicon surfactants, inorganic nanoparticles, soluble metal salts, and oligomers. Among them, inorganic nanoparticles mainly promote the aggregation and nucleation of bubbles on the surface of nanoparticles through their high specific surface area, thereby forming a foaming effect.

[0004] Currently, major domestic enterprises and high-efficiency manufacturers are attempting to improve the selection of nanoparticles. For example, Qing Jingqi, a master's student at the China Academy of Engineering Physics, obtained hollow mesoporous SiO2 nanoparticles in his thesis "Study on Morphology and Properties of Silica Nanoparticles / Rigid Polyurethane Foam Composites" through the sol-gel method. ２ It can reduce the average pore size of foam, when mesoporous SiO2 ２ At a content of 1%, the compression strength of reinforced polyurethane foam increased by 19%, while that of solid spherical SiO2 only increased by 9%. However, this hollow mesoporous spherical SiO2 is prepared using tetraethyl silicate as a raw material and a special process, resulting in high costs and making industrialization difficult. For example, the Beijing Institute of Aeronautical Materials studied the nucleation effect of nanoparticles such as titanium dioxide, alumina, silica, and zirconium dioxide on polyurethane. The addition amount of these nucleating agents generally needs to reach 5-8%, which increases the viscosity of the system during processing and also raises production costs for enterprises. Summary of the Invention

[0005] In order to provide a polyurethane nucleating agent that is easy to prepare, can achieve good foaming effect under low doping conditions, and provides high compression performance, this application provides a method for preparing a silicone-based polyurethane nucleating agent.

[0006] First, this application provides a method for preparing a silicone-based polyurethane nucleating agent, which includes at least the following steps:

[0007] S1. The tetraethyl orthosilicate prepolymer mixture, template agent and silane coupling agent are mixed and reacted to obtain the initial particulate product;

[0008] S2. The template agent is removed by calcination of the initial particulate product to obtain a silicone-based polyurethane nucleating agent;

[0009] The template agent comprises at least the following components by mass percentage:

[0010] Low molecular weight polyamide 5-20%;

[0011] The balance is 4-20 carbon single-chain aliphatic di-terminated amines;

[0012] The mass ratio of the tetraethyl orthosilicate prepolymer mixture, template agent, and silane coupling agent is 100:30-40:5-10.

[0013] In the above scheme, mesoporous silica was prepared by polycondensation, using amino-containing molecular chains as templates and tetraethyl orthosilicate prepolymers as the initial silicon compound. The overall reaction process is as follows:

[0014] First, the bonding of the tetraethyl orthosilicate prepolymer mixture with the template agent occurs simultaneously. In step S1, as the tetraethyl orthosilicate prepolymer mixture further polymerizes, the template agent is incorporated into the formed silica particles, thereby generating a channel structure during the calcination step in step S2. During this process, the low-molecular-weight polyamide forms a certain micelle structure, while the long-chain aliphatic diamine is directly bonded to the particles. Therefore, an overall mesoporous structure with different sizes is formed. Simultaneously, because the particles with dual-terminated aliphatic amines better adsorb micelles, as the reaction proceeds, the resulting particles form worm-like channels near the core and larger radial channels in the outer regions. It should be noted that the low-molecular-weight polyamide is typically a polyamide with an index-average molecular weight of 500–9000. In the above process, the addition of silane coupling agent on the one hand couples some reaction sites and improves the dispersion uniformity of template agent, and on the other hand, silane coupling agent can also provide a certain graft coupling on the surface of the formed mesoporous silica, thereby improving the dispersibility of the nucleating agent prepared.

[0015] After the nucleating agent system is prepared, it first provides a high specific surface area, which leads to good gas storage performance, thereby achieving rapid gas desorption and generating a large pore density. Simultaneously, under the action of the silane coupling agent, the system as a whole has low viscosity-increasing effect, has no impact on the polyurethane processing, and will not aggregate in the system, causing foam collapse or a decrease in mechanical properties. Furthermore, because it forms radial pores with large sizes through low-molecular-weight polyamide, these pores facilitate rapid gas entry and exit. The polyol used to prepare the polyurethane does not enter the pores; instead, it can use the pore openings as anchor points to promote early phase separation or crystallization of local hard segment micro-regions, forming a rigid "shell" and inhibiting bubble coalescence and Ostwald curing. The final polyurethane prepared has a uniform bubble distribution and good compressive strength.

[0016] It should be noted that tetraethyl orthosilicate prepolymer mixtures typically refer to systems containing tetraethyl orthosilicate, tetraethyl orthosilicate oligomers, and silica, such as TEOS, TEOS-28, and TEOS-40. In the above-mentioned scheme, the tetraethyl orthosilicate prepolymer mixture is preferably TEOS-40. TEOS-40 is selected in the system, and after curing, it contains 40% silica by mass. During the reaction process, silica can serve as the basis for the formation of mesoporous silica, thereby providing a more stable and narrower particle size system, which in turn induces more stable foam sizes and a more concentrated pore size distribution in the polyurethane. Meanwhile, the low-molecular-weight polyamide is preferably 200 low-molecular-weight polyamide. The pore structure and gas production of 200 low-molecular-weight polyamide are moderate, which helps to distribute the gas more evenly in the polyurethane system, resulting in better strength of the foamed polyurethane. This strength may be related to the molecular weight and the amine value of the polyamide. The molecular weight determines the chain length, which in turn determines the continuity of the pores and also plays a role in controlling the wall thickness to some extent. The amine value determines the reaction rate with the silane coupling agent; too fast or too slow a rate will lead to problems in mesoporous formation. The silane coupling agent is preferably methyltriethoxysilane. Using methyltriethoxysilane as the silane coupling agent in the reaction does not affect the polyurethane molding process. A small amount of silane coupling agent adsorbed in the pores does not participate in the polyurethane reaction. Therefore, the polyurethane is more likely to generate larger grains near the nucleating agent, effectively improving the overall strength. In addition, a portion of the hydrophobic alkyl system is generated within the pores of methyltriethoxysilane, which can reduce the overall polarity, decrease the adsorption of polyols within the pores, and thus increase the gas generation rate.

[0017] Based on the above, and further preferably, in step S1, tetramethoxysilane is also added, wherein the mass ratio of the tetramethoxysilane to the tetramethoxysilane prepolymer mixture is 1 to 3:100.

[0018] In the above scheme, tetramethoxysilane was added as an auxiliary nucleation system. Tetramethoxysilane has a faster reaction rate and is easily adsorbed onto the silica surface of TEOS-40 in the system. Hydrolysis instantly releases a large amount of Si(OH)4 monomers, which rapidly pin to the micelle surface. The exothermic condensation causes a sudden increase in local supersaturation, providing additional nucleation sites and improving pore density. Simultaneously, the high template content and the added oligoamide system result in stable pore sizes and improved hydrothermal resistance. Therefore, overall, it helps the nucleating agent generate a more uniform bubble system and also enhances the reinforcing effect of the nucleating agent on the polyurethane system.

[0019] Based on the above scheme, in step S1, the tetraethyl orthosilicate prepolymer mixture, template agent, tetramethoxysilane and the first part of silane coupling agent are first reacted until the reaction time is 50 to 75% of the total reaction time, and then the remaining part of silane coupling agent is added. The first part of silane coupling agent accounts for 30 to 60% of the total amount of silane coupling agent.

[0020] In the above scheme, the silane coupling agent is added to the system in two stages. Since tetramethoxysilane has already been added to the system, adding the silane coupling agent in two stages helps to improve the dispersibility of the obtained mesoporous silica, reduce the agglomeration of nucleating agents during preparation and sintering, and further improve the uniformity of particle size distribution. At the same time, the later-added silane coupling agent can also seal the pores, thereby restricting the entry of polyol molecules into the pores, creating a pore structure where gas can pass through but liquid cannot, thus improving the subsequent foaming ability and the compressive strength of the obtained polyurethane.

[0021] Preferably, in step S1, the reaction time is 4–6 h, the reaction temperature is 50–70 °C, the solvent is water or a mixture of water and aprotic organic solvent, and the mass concentration of the tetraethyl orthosilicate prepolymer mixture is 30–50 mg / mL. Under the above reaction conditions, the particle size of the system can be well controlled to form a more uniform pore structure and particle morphology.

[0022] Preferably, step S2 includes the following specific steps:

[0023] S2-1: The prepared particles are rapidly cooled to no higher than 10°C, then centrifuged and washed with ethanol and water;

[0024] S2-2: After drying, calcinate at 550-700℃ for 4-6 hours.

[0025] In the above scheme, rapid cooling can minimize the sedimentation of mesoporous silica, terminate the condensation reaction of the system, reduce the agglomeration effect caused by the increase of particle surface energy due to tetramethoxysilane, and provide better uniformity.

[0026] Preferably, the 4-12 carbon single-chain aliphatic diterminated amine is an octacarbon diamine or a decacarbon diamine.

[0027] In the above scheme, a diamine with an even number of carbons and a relatively long carbon chain is used. The amino groups of the even-numbered carbons in the long chain generally face the same side, making it easier for them to combine with silicon particles and form a stable pore structure. From a product perspective, this provides better gas production performance and better strength.

[0028] In addition, this application also relates to the polyurethane nucleating agent prepared by the above preparation method; the average particle size of the silicon-based polyurethane nucleating agent is 100-150 nm. By controlling the above reaction conditions, a nucleating agent with a particle size of 100-150 nm can be obtained. Its particle size is close to the lattice size formed by polyurethane foam. Therefore, during the foaming process, the polyurethane system formed is more uniform and stable, which helps to better achieve the strength of polyurethane.

[0029] In summary, this application provides a polyurethane nucleating agent that employs a one-step reaction method for polycondensation. It utilizes a composition of tetraethyl orthosilicate and a template agent to form mesoporous silica nanoparticles. By using low-molecular-weight polyamide and aliphatic double-terminated amines as templates and a silane coupling agent to seal the mesoporous channels, it can achieve good gas generation and reinforcement effects. Under the condition of a dosage of only 1%, it significantly improves the compressive strength of the obtained foamed polyurethane. Attached Figure Description

[0030] Figure 1 This is a scanning electron microscope image of Example 1.

[0031] Figure 2 yes Figure 1 The particle size distribution diagram after particle size analysis.

[0032] Figure 3 This is the XRD pattern of Example 1. Detailed Implementation

[0033] The following examples all involve polyurethane nucleating agents, and the nucleating agent products are mainly evaluated through the following two dimensions:

[0034] 1. Based on the product itself, it is necessary to evaluate the macroscopic and microscopic morphology of the mesoporous silica nanoparticles prepared by the nucleating agent, specifically including three dimensions: whether there is agglomeration, particle size, and specific surface area. Particle size is calculated by sampling from SEM images, primarily examining the average particle size and also observing the uniformity of the particle size. Specific surface area is determined using the BET method. Additionally, for some embodiments, the most probable pore size is determined by BJH desorption.

[0035] 2. The product was incorporated into a polyurethane system at a mass fraction of 1% to prepare foamed polyurethane. The density, tear strength, tensile strength, and 10% compressive strength of the foamed polyurethane were then characterized. The foamed polyurethane was prepared using the following method:

[0036] BASF's polyurethane black component M20S and polyurethane white component Elastopor CH1141C-A were selected and added at a black component / white component mass ratio of 1.2:1. 1% of the following nucleating agent was added. The mixture was then injected into a foaming mold at a pressure of 130 bar, a material temperature of 18-20°C, and a flow rate of 400 g / s. The mold temperature was 40°C. After curing for 5 minutes, the foam was demolded and placed at room temperature for 24 hours. The foam was then cut into sample sizes for later use.

[0037] The technical solution of this application will be further described through the following specific embodiments.

[0038] Example 1: This example provides a method for preparing a silicone-based polyurethane nucleating agent, specifically including the following steps:

[0039] S1. TEOS-40 (Cefoperazone CFS-062), template agent, silane coupling agent, and tetramethoxysilane are mixed and reacted in water to obtain a primary granular product. The components added to the system, using water as the solvent per 100 mL, are as follows:

[0040] TEOS-40: 5g;

[0041] Template agent, 2g in total, specifically includes 0.2g of low molecular weight polyamide and 1.8g of octane-2-terminated amine. The low molecular weight polyamide is type 200, specifically Haiyan TY-200, with an amine value of 245mgKOH / g.

[0042] The silane coupling agent, specifically methyltriethoxysilane, is selected in a mass of 0.5g.

[0043] Tetramethoxysilane, 0.1g.

[0044] Specifically, the reaction process in step S1 is as follows:

[0045] The silane coupling agent was divided into two 0.25g portions. One portion of the silane coupling agent was used as the first silane coupling agent, which was first mixed with TEOS-40, template agent, and tetramethoxysilane, and then added to water. The temperature was controlled at 60℃, and the mixture was stirred at 500rpm for 2.5h. Then the remaining silane coupling agent was added, and the reaction was continued for another 2.5h to obtain the initial granular product.

[0046] S2. Calcine the initial granules to remove the template agent, specifically including the following steps:

[0047] S2-1. By adding an ice-water mixture, the system temperature is quickly lowered to no higher than 10°C. Then, the system is rapidly centrifuged, the supernatant is removed, and the system is washed twice with water and ethanol, respectively.

[0048] S2-2, after the above system is dried, it is then calcined at 600℃ for 5 hours to obtain the polyurethane nucleating agent.

[0049] In Example 1, the particle morphology of the prepared polyurethane nucleating agent under a scanning electron microscope is as follows: Figure 1 As shown, its particle size distribution is as follows: Figure 2 As shown, the XRD pattern is as follows Figure 3 As shown. In Example 1, the prepared product had an average particle size of 128.5 nm and a specific surface area of ​​898 m². 2 / g, the most probable pore size was determined to be 5.58nm by BJH desorption.

[0050] Example 2: Based on Example 1, this example investigates the optimal particle size of the polyurethane nucleating agent in the system by adjusting the preparation process. Specifically, based on Example 2, the mass ratio of TEOS-40, template agent, silane coupling agent, and tetramethoxysilane was kept constant, and other process parameters were adjusted to obtain the experimental results shown in Table 1.

[0051]

[0052] Overall, the particle size and specific surface area are approximately inversely proportional. However, as the particle size decreases further, due to its higher surface energy and faster reaction rate, the loading of the template agent in the system will be slower than that of larger-sized particles, resulting in a smaller increase in its specific surface area.

[0053] The results of the verification of Examples 1 and 2 in polyurethane are shown in Table 2.

[0054]

[0055] As shown in Table 2, the particle size selection significantly affects the performance of polyurethane. Generally, with similar particle morphology, increasing the particle size leads to a decrease in the specific surface area and gas generation performance of the system, which in turn weakens the mechanical properties of the system. Conversely, excessively small mesoporous silica particles result in a decrease in effective nucleation, a tendency for viscosity to increase during the reaction process, and a greater likelihood of agglomeration of mesoporous silica particles, leading to the formation of large pores between particles and a significant decrease in the strength of the polyurethane.

[0056] Example 3, based on Example 1, further investigated the role of different tetraethyl orthosilicate prepolymer mixtures in the system, and compared the effects of adding silane coupling agents and tetramethoxysilane to verify the influence of the selection of tetraethyl orthosilicate prepolymer mixtures on the system. In this example, two tetraethyl orthosilicate systems, TEOS-28 and TEOS-40, were selected, and the specific experimental results are shown in Table 3.

[0057]

[0058] The data in Table 3 show that the system is more prone to agglomeration when no silane coupling agent is added, while tetramethoxysilane helps to reduce the most probable pore size and the average particle size to some extent.

[0059] Furthermore, the experimental data above shows that under the same reaction conditions, TEOS-28 generally forms a channel structure with a smaller size than TEOS-40, which is reflected in the increase of specific surface area and the reduction of the most probable pore size. To improve the comparative performance, after further adjusting the amount of TEOS-28 and other parameters, Examples 3-6 were obtained to achieve a particle size similar to the product in Example 1. Specifically, the adjusted experimental conditions and the parameters of the final product are as follows:

[0060] Based on a per 100 mL solvent volume, the mass of TEOS-28 was 7.5 g, the template and selected low-molecular-weight polyamide 0.5 g, the octane diamine 2.5 g, the silane coupling agent 0.75 g, and the mass of tetramethoxysilane remained constant. The reaction temperature was 45 °C, and all other conditions remained constant. The resulting mesoporous silica had an average particle size of 110.6 nm and a specific surface area of ​​1035.9 m². 2 / g, most probable pore size 5.20nm.

[0061] The overall verification of Example 3 was performed, and the results are shown in Table 4.

[0062]

[0063] The experimental results in Table 4 show that, in terms of overall comparison, although the addition of silane coupling agent has a relatively small impact on the overall specific surface area and particle size, its absence leads to significant particle agglomeration, ultimately affecting product molding. Furthermore, it tends to disperse unevenly in the polyurethane system, resulting in a significant loss of overall strength in the final polyurethane system. In contrast, tetramethoxysilane effectively enriches the particle pores in the system, significantly improving the overall tear strength and tensile strength of the polyurethane.

[0064] Example 4: Based on Example 1, this example further verifies the timing, dosage, and type of silane coupling agent. Specifically, the experimental groups are shown in Table 5.

[0065]

[0066] It should be noted that, overall, the timing of the addition of the silane coupling agent has a relatively small impact on the final particle size obtained from the reaction, and the silane coupling agent added in the early stage will appropriately increase the specific surface area, but the overall impact is small. Therefore, it can be considered that the influence of different experimental groups on the strength of polyurethane in this embodiment is not due to the particle morphology.

[0067] Furthermore, the experimental results above show that the timing of the addition of silane coupling agent significantly affects the dispersibility of particles. In the presence of tetramethylsilane, if the amount of silane coupling agent added too early or too late, it will lead to a certain degree of agglomeration in the system. The reason may be that adding it too early will cause the silane coupling agent to bind inside the mesoporous silica, thus failing to achieve the dispersion effect. If it is added too late, a certain degree of agglomeration will also occur during the reaction, resulting in a decrease in specific surface area and poor morphology.

[0068] Further experiments were conducted on the experimental groups in Table 5, and the results are shown in Table 6.

[0069]

[0070] In the above scheme, it can be seen that the silane coupling agent needs to be added in two stages, with the second addition occurring in the middle to later part of the reaction process. This is because, after the reaction has progressed to a certain extent, it is crucial to disperse the mesoporous silica during its initial formation using the silane coupling agent. Furthermore, among various silane coupling agents, only the carbosilyl-bonded methyltriethoxysilane exhibits better performance. On one hand, it helps reduce the intrusion of polyols into the pores, thus improving the overall mechanical properties of the polyurethane and the gas-generating performance of the system. On the other hand, it also reduces the impact of the nucleating agent on the system viscosity. Additionally, the aggregation of the nucleating agent can significantly affect the gas-generating performance and mechanical strength.

[0071] It should be noted that in Examples 4-10, an excessive amount of silane coupling agent was added, even though its particle size was still within the system range and its specific surface area reached 808 m². 2 / g, but due to the excessive silane coupling agent on its surface, the nucleating agent system is difficult to bond with the polyurethane system, thus affecting the final mechanical properties of the polyurethane. In Examples 4-11 to 4-14, compared with Example 1, the silane coupling agent was changed, and silane coupling agents with acyloxy and amino groups were used respectively. Overall, they had lower mechanical properties than the examples. This may be because methyltriethoxysilane has less impact on the polyurethane curing reaction process, while also providing better hydrophobicity, thus leading to a certain improvement in strength.

[0072] Example 5: Based on Example 1, the amount of tetramethoxysilane added was adjusted. The specific amount of tetramethoxysilane added and the corresponding experimental results are shown in Table 7.

[0073]

[0074] The experimental results show that the addition of tetramethoxysilane not only reduces the particle size and increases the specific surface area of ​​the system, but also controls the pores of mesoporous silica to achieve better gas production and strength. At the same time, it provides better strength because it provides a partially distorted lattice structure. However, when too much tetramethoxysilane is added, it can also cause the system to agglomerate due to the excessively fast reaction rate, which in turn leads to a loss of strength.

[0075] Example 6: Based on Example 1, this example orthogonally adjusts the types and proportions of different low molecular weight polyamides. The specific experimental groups are shown in Table 8.

[0076]

[0077] In the table above, the 650 low molecular weight polyamide is specifically selected from Haiyan TY-650, with an amine value of 215 mg KOH / g, and the 651 low molecular weight polyamide is specifically selected from Haiyan TY-651, with an amine value of 393 mg KOH / g.

[0078] Experiments were conducted on the nucleating agents listed in Table 8, and the results are shown in Table 9.

[0079]

[0080] The experimental data above shows that, with a fixed overall amount of template agent, adding a small amount of oligomeric amide can significantly improve the strength of the system. This is because the polyamide-templated system forms a partially macroporous structure. This macroporous structure allows for rapid reaction between the polyol and isocyanate, thus acting as better anchoring points. This allows the polyurethane molecular chains to better entangle around the nucleating agent, thereby increasing strength. Simultaneously, the large pores formed by the polyurethane also facilitate rapid and uniform gas production, stabilizing density and improving bubble uniformity. While the overall density is not significantly affected, the compressive strength of the system is noticeably improved. However, excessive polyurethane addition can lead to increased wall thickness and reduced specific surface area of ​​the mesoporous silica. Furthermore, experiments revealed that type 200 low-molecular-weight polyamide provided better overall strength performance in the above system. This may be due to its moderate amine value, which improves reaction mildness and reduces defects, and possibly also to its superior molecular chain flexibility.

[0081] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a silicon-based polyurethane nucleating agent, characterized by, At least comprising the following steps: S1, mixing and reacting tetraethyl orthosilicate pre-polymer mixture, template agent and silane coupling agent to obtain particle primary product, the specific method is as follows: First, reacting tetraethyl orthosilicate pre-polymer mixture, template agent, tetramethoxysilane and first part of silane coupling agent, until the reaction time is 50-75% of the total reaction time, then adding the remaining part of silane coupling agent, the first part of silane coupling agent accounts for 30-60% of the total amount of silane coupling agent; S2, removing the template agent by calcination to obtain silicon-based polyurethane nucleating agent from the particle primary product; The template agent comprises at least the following components in mass percentage: Low molecular weight polyamide 5-20%; 4-12 carbon single-chain fatty double-end amine remainder; The mass ratio of the tetraethyl orthosilicate pre-polymer mixture, template agent and silane coupling agent is 100:30-40:5-10; The low molecular weight polyamide is 200 low molecular weight polyamide; The 4-12 carbon single-chain fatty double-end amine is octane diamine or decane diamine; The silane coupling agent is methyl triethoxysilane; The mass ratio of tetramethoxysilane and tetraethyl orthosilicate pre-polymer mixture is 1-3:

100.

2. The method for preparing a silicon-based polyurethane nucleating agent according to claim 1, characterized in that, The tetraethyl orthosilicate pre-polymer mixture is TEOS-40.

3. The method for preparing a silicone-based polyurethane nucleating agent according to claim 1, characterized in that, In step S1, the reaction time is 4-6h, the reaction temperature is 50-70℃, the solvent is water or a mixture of water and aprotic organic solvent, and the mass concentration of tetraethyl orthosilicate pre-polymer mixture is 30-50mg / mL.

4. The method for preparing a silicone-based polyurethane nucleating agent according to claim 1, characterized in that, In the step S2, the specific steps are as follows: S2-1: rapidly cooling the prepared particles to not higher than 10℃, then centrifuging and washing with ethanol and water; S2-2: after drying, calcining at 550-700℃ for 4-6h.

5. The silicon-based polyurethane nucleating agent prepared by the method according to any one of claims 1 to 4, characterized in that, The average particle size of the silicon-based polyurethane nucleating agent is 100-150nm.

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