A preparation method of a polyorganosiloxane

Abstract

A preparation method and application of a polyorganosiloxane belong to the technical field of polyorganosiloxane preparation. The method includes putting cyclic siloxane, organosilane coupling agent and polyol into a reaction kettle, carrying out negative pressure nitrogen replacement to remove oxygen, and heating for reaction; controlling the temperature in the kettle, respectively dropping epichlorohydrin and propylene oxide, adding an acidic catalyst, carrying out aging reaction, removing unreacted monomers, and carrying out post-treatment to obtain a polyorganosiloxane product. The polyorganosiloxane prepared by the present invention has high reactivity, excellent water resistance and durability, and is suitable for the preparation of high-performance rigid polyurethane foam plastics.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicone materials, and particularly relates to a preparation method of a polyorganosiloxane. Background Art

[0002] With the wide application of high-performance materials, polyorganosiloxane, as an important silicone compound, has gradually become an important research object in the field of polymer materials due to its excellent heat resistance, weather resistance, and low surface energy. However, the existing preparation methods of polyorganosiloxane still have some deficiencies in reaction efficiency, product purity, and application performance, which limit its wide application in industrial production.

[0003] Chinese Patent CN101775141B provides a preparation method of a castor oil-based polyorganosiloxane polyol. In this invention, a hydrosilylation reaction of castor oil and pentamethyldisiloxane forms a castor oil hydrosilylation product, which is then subjected to an acid-catalyzed ring-opening reaction with a cyclic siloxane to finally prepare a castor oil-based polyorganosiloxane polyol. This method has a simple synthesis process and low cost. The obtained product can significantly reduce the surface energy of the material without reducing its mechanical properties and improve the water resistance of the material, especially suitable for synthesizing waterborne polyurethane materials. However, in this technical solution, the raw material selection and reaction condition control in the synthesis process are relatively single, which may limit the improvement space of reaction efficiency and product purity. In addition, while the polyol prepared by this method improves the surface properties of the material, its improvement of the mechanical properties and durability of the material is limited, making it difficult to meet the requirements of some high-end applications.

[0004] Another Chinese Patent CN115594837B provides a preparation method and application of a modified polyorganosiloxane polyol. In this invention, a raw material containing a phenolic compound and an alkanolamine compound is mixed and heated for reaction, and then propylene oxide and a polyether-modified polyorganosiloxane are added for nitrogen replacement and a secondary reaction to prepare a polyether polyol product. This method improves the emulsification reaction efficiency of the polyol product in the foam reaction, significantly improves the fineness of the foam cells, and reduces the surface bubbles of the rigid polyurethane foam. However, in this technical solution, the reaction process is relatively complex and the types of raw materials are numerous, which may lead to high production costs and great difficulty in process control. In addition, while the polyol prepared by this method improves the foam properties, its improvement of the overall properties of the material and the expansion of the application scope are relatively limited, making it difficult to meet the requirements of some special application fields.

[0005] Rigid foam is an important application form of polyurethane materials. Especially in the field of exterior walls of building insulation materials, the proportion of rigid polyurethane foam in China is 7%, while in the United States it is 65%, indicating that there is still great room for improvement. Secondly, the rapid development of cold chain logistics in China will bring greater demand for rigid foam. At the same time, the applications in refrigerators and electric water heaters are stable and improving. In the past 40-odd years, 141b has been the main blowing agent for the production of polyurethane foam in fields such as refrigerator insulation, pipeline insulation, energy-saving buildings, and furniture manufacturing. To meet the requirements of environmental protection, extensive research has been carried out on alternative technologies in various countries. Currently, in the refrigerator industry, pentane blowing agents are mainly used. Using the n-pentane system can reduce the foam density by about 6% compared with the cyclopentane system. Moreover, the low-boiling n-pentane system can provide excellent processing performance, good fluidity, and has comparable foam mechanical properties to the cyclopentane system. However, due to the relatively large number of surface bubbles in the foam plastics made of n-pentane, the surface bubbles of the foam increase significantly compared with the cyclopentane system.

[0006] Therefore, it becomes particularly important to effectively improve the performance defects of n-pentane-based formulations in the application of formulations. Thus, developing a modified polysiloxane polyol can effectively improve the dimensional stability of rigid polyurethane foam plastics made from n-pentane-based formulations and reduce the thermal conductivity. Therefore, the development of the application of modified polysiloxane polyol in the rigid foam system is extremely urgent. The above problems indicate that there are still certain deficiencies in the existing preparation methods of polysiloxane in terms of reaction efficiency, product purity, mechanical properties, durability, and application scope. Therefore, the present invention provides a preparation method of poly-siloxane, which can improve the reaction efficiency and product purity by optimizing the raw material selection and reaction conditions. At the same time, without reducing the mechanical properties of the material, it can significantly reduce the surface energy of the material, improve the water resistance and durability of the material, and meet the requirements of modern industry for high-performance polysiloxane materials. Summary of the Invention

[0007] In order to overcome the deficiencies in the existing polysiloxane preparation methods, such as low reaction efficiency, low product purity, and limited improvement in mechanical properties and durability, the present invention provides a preparation method and application of poly-siloxane. The poly-siloxane prepared by the present invention has high reaction activity, excellent water resistance and durability, and is suitable for the preparation of high-performance rigid polyurethane foam plastics.

[0008] The preparation method of the poly-siloxane described in the present invention includes the following steps:

[0009] 1) Put cyclic siloxane, organosilane coupling agent, and polyol into a reaction kettle, seal the kettle, perform negative pressure nitrogen replacement to remove oxygen, and heat for reaction;

[0010] 2) Control the temperature in the kettle, continuously add epichlorohydrin for the first time, control the material temperature and the pressure in the kettle during the reaction process. After the addition is completed, carry out a curing reaction, add an acidic catalyst, seal the kettle, and perform a negative pressure replacement and deoxygenation operation;

[0011] 3) Control the temperature in the kettle, continuously add propylene oxide for the second time, control the material temperature and the pressure in the kettle during the reaction process. After the addition is completed, carry out a curing reaction and remove the unreacted monomers;

[0012] 4) Post-treatment and refining to obtain a polysiloxane product.

[0013] The polysiloxane product of the present invention has high reactivity, excellent water resistance and durability, and is suitable for the preparation of high-performance rigid polyurethane foams. Using cyclic siloxanes, organosilane coupling agents and polyols as composite initiator raw materials, a product with a hydroxyl value of 400 - 450 mg / KOH and a viscosity of 20000 - 35000 mPa·s can be obtained. The combination of the composite initiators exerts a synergistic effect, improving the efficiency of polysiloxane in the reaction, and the product has higher reactivity and better properties. It solves the problem of poor mutual solubility of each component when adding a single component, and improves the purity and reaction efficiency of the product.

[0014] Among them: it includes the following raw materials in parts by weight: cyclic siloxane: 15 - 25 parts; organosilane coupling agent: 3 - 8 parts; polyol: 10 - 18 parts; epichlorohydrin: 6 - 15 parts; acidic catalyst: 0.1 - 0.3 parts; propylene oxide: 50 - 70 parts. By optimizing the raw material ratio, the prepared polysiloxane has high reactivity, excellent water resistance and durability, can meet the preparation requirements of high-performance rigid polyurethane foams, significantly improve the dimensional stability of the foam and reduce the thermal conductivity. In addition, this raw material combination ensures high performance while avoiding the use of too many complex raw materials, reducing production costs and process control difficulties, and is suitable for large-scale industrial production.

[0015] The cyclic siloxane described above includes: one or several of cyclotrisiloxane, cyclotetrasiloxane, cyclopentasiloxane, and cyclohexasiloxane. These cyclic siloxanes can efficiently carry out ring-opening polymerization reactions under the action of a catalyst, and the reaction conditions are mild and easy to control, thus significantly improving production efficiency. The combination of different cyclic siloxanes can adjust the molecular structure and properties of polysiloxane. For example, cyclotrisiloxane and cyclotetrasiloxane can provide good thermal stability and mechanical properties, while cyclopentasiloxane and cyclohexasiloxane can further improve the flexibility and durability of the product. By selecting different types of cyclic siloxanes, polysiloxanes suitable for various application fields can also be prepared to meet the needs of different scenarios.

[0016] The silane coupling agents described above include one or more of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. By using these silane coupling agents, not only can the molecular structure of the polysiloxane be optimized, but also the problem of poor miscibility of single components can be effectively solved, further improving the purity and reaction efficiency of the product, making it more suitable for the preparation of high-performance rigid polyurethane foams. Preferably, the silane coupling agent is γ-glycidoxypropyltrimethoxysilane, and its epoxy group can undergo a crosslinking reaction with the hydroxyl group in the polyol, further enhancing the mechanical properties and water resistance of the product.

[0017] The polyols described above include one or more of glycerol, sorbitol, pentaerythritol, ethylene glycol, and diethylene glycol. These polyols are widely sourced, low-cost, and exhibit good compatibility and reactivity during the reaction, effectively improving the reaction efficiency and product purity. Preferably, the polyol is sorbitol or diethylene glycol, which can adjust the flexibility and water resistance of the product, making it more suitable for the preparation of high-performance rigid polyurethane foams.

[0018] The acidic catalyst described above includes sulfuric acid, etc.

[0019] In step 1), the temperature of the heating reaction is 110°C to 150°C, and the time is 2 h to 4 h. This combination of temperature and time can not only ensure the rapid progress of the reaction but also avoid the occurrence of excessive side reactions, thereby improving the reaction efficiency and optimizing the product performance, ensuring the purity and stability of the product, and making its hydroxyl value and viscosity meet the design requirements. Preferably, the temperature of the heating reaction is 120°C to 130°C, and the time is 2.5 h to 3.5 h.

[0020] In step 2), the temperature inside the kettle is 110°C to 150°C, the temperature of the material is 110°C to 160°C, the pressure inside the kettle is 0.1 MPa to 0.5 MPa, and the curing time is 2 h to 4 h. The appropriate temperature range provides sufficient heat energy for the ring-opening reaction of epichlorohydrin, ensuring that it can efficiently react with cyclic siloxane, silane coupling agent, and polyol, while avoiding side reactions or decomposition caused by excessive temperature. Secondly, by controlling the pressure inside the kettle, the reaction system can be further stabilized, reducing the generation of impurities, thereby improving the purity and quality of the product. The 2 - 4 hour curing time ensures the full progress of the reaction while avoiding performance degradation caused by overreaction. Under these process conditions, not only is the reaction efficiency improved, but also the controllability of the reaction process is ensured.

[0021] In step 3), the temperature inside the kettle is 120°C to 160°C, the temperature of the material is 120°C to 160°C, the pressure inside the kettle is 0.1 MPa to 0.5 MPa, and the aging time is 2 h to 4 h. By optimizing the reaction conditions, the reaction activity, water resistance, and durability of the polysiloxane are further improved to meet the requirements of high-end applications such as high-performance rigid polyurethane foams.

[0022] The post-treatment in step 4) includes the following steps: lowering the temperature inside the kettle to 70°C to 90°C, adding an alkali solution and water, stirring, adding activated clay, heating to 110°C to 130°C, evacuating to dehydrate, controlling the pressure inside the kettle at -0.09 MPa to -0.07 MPa, detecting that the moisture content is lower than 0.1%, discharging the material, and filtering to obtain the polysiloxane product. Adding the alkali solution can neutralize the acidic catalyst used in the reaction to prevent the residual acid from corroding or degrading the product, thereby improving the stability and storage performance of the product; secondly, the activated clay can adsorb the impurities and low-molecular-weight by-products generated during the reaction, further improving the product purity. In addition, by strictly controlling the heating and vacuum dehydration steps, it is ensured that the water content of the product is lower than 0.1%, which is crucial for improving the reaction activity, water resistance, and durability of the polysiloxane. Especially when used in high-performance rigid polyurethane foams, it can reduce the pore defects in the foam and improve the dimensional stability and mechanical properties of the foam.

[0023] For the polysiloxane product described, the hydroxyl value is 400 mg / KOH to 450 mg / KOH, and the viscosity is 20000 mPa·s to 35000 mPa·s.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The present invention uses cyclic siloxanes, organosilane coupling agents, and polyols as composite initiator raw materials, and a product with a hydroxyl value of 400 mg / KOH to 450 mg / KOH and a viscosity of 20000 mPa·s to 35000 mPa·s can be obtained. The combination of the composite initiators exerts a synergistic effect, improving the efficiency of the polysiloxane in the reaction, and the product has higher reaction activity and better performance.

[0026] 2. This production process and formulation technology solve the problem of poor mutual solubility of each component when adding a single component, and improve the purity and reaction efficiency of the product.

[0027] 3. The high hydroxyl value and high viscosity system of the polysiloxane of the present invention effectively increases the crosslinking degree during the foaming process of the rigid polyurethane foam product, and improves the dimensional stability and mechanical properties of the product.

[0028] 4. During the reaction of the polysiloxane prepared by the present invention with the isocyanate black material, the produced foam has delicate cell structure and uniform density distribution. The rigid polyurethane foam made therefrom has smaller cell size and fewer surface bubbles, significantly improving the water resistance and durability of the material. Detailed Embodiments

[0029] The present invention will be further described below through specific embodiments, and Embodiment 1 is the best embodiment. Embodiment 1

[0030] 15 parts of cyclotetrasiloxane, 5 parts of γ-aminopropyltriethoxysilane, 12 parts of glycerol, 12 parts of epichlorohydrin, 0.2 part of sulfuric acid and 60 parts of propylene oxide are used as raw materials. First, the cyclotetrasiloxane, γ-aminopropyltriethoxysilane and glycerol in the above raw materials are weighed according to the ratio and then put into a reaction kettle. The reaction kettle is a stainless steel reaction kettle with a stirrer and a heating device to ensure that the raw materials can be fully mixed and heated evenly during the reaction. Seal the reaction kettle and use negative pressure nitrogen to replace oxygen to ensure an oxygen-free environment in the kettle, prevent the raw materials from undergoing oxidation reactions at high temperatures and affect the performance of the product. The specific operation of replacing oxygen is as follows: reduce the pressure in the kettle to -0.09 MPa and keep it for 10 minutes, then slowly fill in nitrogen to restore the pressure in the kettle to normal pressure, and repeat this operation 3 times to completely discharge the oxygen in the kettle.

[0031] After the sealing operation of the kettle is completed, turn on the heating device, gradually raise the temperature in the kettle to 110 °C, and keep it at this temperature for 2 hours for the heating reaction. After the heating reaction is completed, the temperature in the kettle should be kept within the range of 110 °C to 150 °C, and epichlorohydrin is continuously added dropwise through a pipeline for 1 hour. During the dropping process, control the temperature in the kettle to be 130 °C, the material temperature to be 140 °C, and the pressure in the kettle to be 0.3 MPa. After the dropping is completed, continue the curing reaction at 130 °C for 3 hours. After the curing reaction is completed, add 0.2 part of sulfuric acid as an acidic catalyst, seal the reaction kettle again, and perform negative pressure nitrogen replacement to remove oxygen. Reduce the pressure in the kettle to -0.09 MPa and keep it for 10 minutes, then slowly fill in nitrogen to restore the pressure in the kettle to normal pressure, and repeat this operation 3 times to ensure an oxygen-free environment in the kettle.

[0032] After adding sulfuric acid, control the temperature in the kettle to be 110 °C to 150 °C, the material temperature to be 140 °C, and the pressure in the kettle to be 0.3 MPa, and continuously add propylene oxide dropwise through a pipeline for 1 hour. After the dropping is completed, continue the curing reaction at 140 °C for 3 hours. After the curing reaction is completed, perform the operation of removing unreacted monomers. The specific steps are as follows: lower the temperature in the kettle to 100 °C, turn on the condenser at the top of the kettle, and reduce the pressure in the kettle to -0.09 MPa through an air extraction pump and keep it for 30 minutes to ensure that the unreacted monomers are completely removed.

[0033] After removing the monomers, post-treatment and refining operations are carried out. The temperature in the kettle is reduced to 80 °C, and a 20% sodium hydroxide solution and distilled water are added. The addition amount of the sodium hydroxide solution is 1% of the total mass of the raw materials, and the addition amount of water is 20% of the total mass of the raw materials. The stirrer is started, and the stirring time is 30 minutes to ensure that the lye and water are fully mixed with the raw materials, neutralize the acidic catalyst, and terminate the reaction. Activated clay is added, and the addition amount of the activated clay is 1% of the total mass of the raw materials, and stirring continues for 30 minutes. The residual substances in the reaction process are adsorbed by the activated clay to improve the purity of the product. The temperature in the kettle is raised to 120 °C, the vacuum device is started, the pressure in the kettle is reduced to -0.09 MPa, and this is maintained for 30 minutes for dehydration operation. After the dehydration operation is completed, the water content in the kettle is detected by a moisture detector to ensure that the water content is lower than 0.1%. Discharging is carried out, and the activated clay and other residual substances are filtered off through a filtering device, and finally a polysiloxane product is obtained. Example 2

[0034] 25 parts of cyclohexasiloxane, 8 parts of γ-glycidoxypropyltrimethoxysilane, 10 parts of pentaerythritol, 8 parts of epichlorohydrin, 0.3 part of sulfuric acid and 50 parts of propylene oxide are used as raw materials. The preparation steps are the same as those in Example 1. The specific operating conditions are as follows: After cyclohexasiloxane, γ-glycidoxypropyltrimethoxysilane and pentaerythritol are put into the reaction kettle, the kettle is sealed, and negative pressure nitrogen replacement is carried out to remove oxygen. The pressure in the kettle is reduced to -0.09 MPa and maintained for 10 minutes, and then nitrogen is slowly filled in to restore the pressure in the kettle to normal pressure. This operation is repeated 3 times. After the replacement and deoxygenation are completed, the heating device is started, and the temperature in the kettle is gradually raised to 150 °C and maintained at this temperature for 3 hours for the heating reaction. After the heating reaction is completed, epichlorohydrin is continuously added dropwise through a pipeline at 150 °C for 1 hour. During the dropping process, the temperature in the kettle is controlled at 150 °C, the material temperature is 160 °C, and the pressure in the kettle is 0.5 MPa. After the dropping is completed, the curing reaction is continued at 150 °C for 4 hours. After the curing reaction is completed, 0.3 part of sulfuric acid is added as an acidic catalyst, the kettle is sealed again, negative pressure nitrogen replacement is carried out to remove oxygen, the pressure in the kettle is reduced to -0.09 MPa and maintained for 10 minutes, and then nitrogen is slowly filled in to restore the pressure in the kettle to normal pressure. This operation is repeated 3 times to ensure an oxygen-free environment in the kettle.

[0035] After adding sulfuric acid, control the temperature in the kettle to 120°C - 160°C, the material temperature to 150°C, and the pressure in the kettle to 0.5 MPa. Continuously drip propylene oxide through a pipeline for 1 hour. After the dripping is completed, continue the curing reaction at 150°C for 4 hours. After the curing reaction is completed, perform the operation of removing unreacted monomers. The specific steps are as follows: lower the temperature in the kettle to 100°C, turn on the condenser at the top of the kettle, and use a vacuum pump to reduce the pressure in the kettle to -0.09 MPa and maintain it for 30 minutes to ensure that unreacted monomers are completely removed. After removing the monomers, perform post-treatment and refining operations. Lower the temperature in the kettle to 90°C, add 20% sodium hydroxide solution and distilled water. The addition amount of the sodium hydroxide solution is 1% of the total mass of the raw materials, and the addition amount of water is 20% of the total mass of the raw materials. Turn on the stirrer and stir for 30 minutes to ensure that the lye, water, and raw materials are fully mixed to neutralize the acidic catalyst and terminate the reaction. Add activated clay, and the addition amount of activated clay is 1% of the total mass of the raw materials, and continue to stir for 30 minutes. Adsorb the residual substances in the reaction process through activated clay to improve the purity of the product. Raise the temperature in the kettle to 120°C, turn on the vacuum device, reduce the pressure in the kettle to -0.09 MPa, and maintain it for 30 minutes for dehydration operation. After the dehydration operation is completed, detect the water content in the kettle through a moisture detector to ensure that the water content is lower than 0.1%. Discharge the material, filter out the activated clay and other residual substances through a filtering device, and finally obtain a polysiloxane product. Example 3

[0036] 20 parts of cyclotrisiloxane, 6 parts of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 15 parts of ethylene glycol, 9 parts of epichlorohydrin, 0.2 part of sulfuric acid, and 65 parts of propylene oxide are used as raw materials. The preparation steps are the same as those in Example 1 and Example 2. The specific operating conditions are as follows: Weigh cyclotrisiloxane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and ethylene glycol in proportion and put them into the reaction kettle. Seal the kettle and perform negative pressure nitrogen replacement to remove oxygen. Reduce the pressure in the kettle to -0.09 MPa and maintain it for 10 minutes, then slowly fill it with nitrogen to restore the pressure in the kettle to normal pressure. Repeat this operation 3 times. After the replacement and oxygen removal are completed, turn on the heating device and gradually raise the temperature in the kettle to 120°C, and maintain it at this temperature for 3 hours for the heating reaction. After the heating reaction is completed, continue to continuously drip epichlorohydrin through a pipeline at 120°C for 1 hour. During the dripping process, control the temperature in the kettle to 120°C, the material temperature to 130°C, and the pressure in the kettle to 0.3 MPa. After the dripping is completed, continue the curing reaction at 120°C for 3 hours. After the curing reaction is completed, add 0.2 part of sulfuric acid as an acidic catalyst, seal the reaction kettle again, perform negative pressure nitrogen replacement to remove oxygen, reduce the pressure in the kettle to -0.09 MPa and maintain it for 10 minutes, then slowly fill it with nitrogen to restore the pressure in the kettle to normal pressure. Repeat this operation 3 times to ensure an oxygen-free environment in the kettle.

[0037] After adding sulfuric acid, control the temperature in the kettle at 130°C to 150°C, the material temperature at 140°C, and the pressure in the kettle at 0.3 MPa. Continuously dropwise add propylene oxide through a pipeline for 1 hour. After the dropwise addition is completed, continue the curing reaction at 140°C for 3 hours. After the curing reaction is completed, perform the operation of removing unreacted monomers. The specific steps are as follows: lower the temperature in the kettle to 100°C, turn on the condenser at the top of the kettle, and lower the pressure in the kettle to -0.09 MPa through an air extraction pump and maintain it for 30 minutes to ensure that the unreacted monomers are completely removed. After removing the monomers, perform post-treatment and refining operations. Lower the temperature in the kettle to 85°C, add 20% sodium hydroxide solution and distilled water. The addition amount of the sodium hydroxide solution is 1% of the total mass of the raw materials, and the addition amount of water is 20% of the total mass of the raw materials. Turn on the stirrer and stir for 30 minutes to ensure that the lye and water are fully mixed with the raw materials, neutralize the acidic catalyst, and terminate the reaction. Add activated clay, and the addition amount of the activated clay is 1% of the total mass of the raw materials. Continue to stir for 30 minutes to adsorb the residual substances in the reaction process through the activated clay and improve the purity of the product. Raise the temperature in the kettle to 120°C, turn on the vacuum device, lower the pressure in the kettle to -0.09 MPa, and maintain it for 30 minutes for dehydration operation. After the dehydration operation is completed, detect the water content in the kettle through a water content detector to ensure that the water content is lower than 0.1%. Discharge the material, filter out the activated clay and other residual substances through a filtering device, and finally obtain a polysiloxane product. The hydroxyl value range of the obtained polysiloxane product is 400 - 450 mg / KOH, and the viscosity range is 20000 - 35000 mPa·s.

[0038] It can be seen from the above examples that the preparation method of the present invention can obtain polysiloxanes with excellent performance under different raw material ratios and reaction conditions. The key of the present invention lies in the combination of the composite initiator. Through the synergistic effect of cyclic siloxane, organosilane coupling agent and polyol, the efficiency of polysiloxane in the reaction is improved, and a polysiloxane product with high hydroxyl value and high viscosity is obtained.

[0039] The polysiloxane product of the present invention is particularly suitable for the preparation of high-performance rigid polyurethane foams. In specific applications, the polysiloxane product can be used as one of the raw materials of rigid polyurethane foams and react with isocyanate black material to form foams. For example, in the process of preparing rigid polyurethane foams, first, the polysiloxane product is mixed with isocyanate black material in a certain proportion, and the mixing ratio can be adjusted according to specific application requirements. Usually, the mass ratio of the polysiloxane product to the isocyanate black material is 1:1.2 - 1.5. After mixing, the mixture is poured into a mold for foaming reaction. The temperature of the foaming reaction is generally 70 - 80 °C, and the time is 3 - 5 minutes. During this process, the high hydroxyl value and high viscosity system of the polysiloxane product effectively increase the crosslinking degree of the foam during foaming, improving the dimensional stability and mechanical properties of the product. At the same time, due to the excellent water resistance and durability of polysiloxane, the prepared rigid polyurethane foams show smaller cell sizes and fewer surface bubbles during application, significantly enhancing the water resistance and durability of the material.

[0040] In order to further verify the performance of the present invention, the following experiments were carried out:

[0041] Experiment 1: Take the polysiloxane product prepared in Example 1, mix it with isocyanate black material at a mass ratio of 1:1.2, pour it into a mold, and carry out a foaming reaction. The reaction temperature is 75 °C, and the reaction time is 4 minutes. After the foaming reaction is completed, take out the foam plastic sample for performance testing. The test results show that the cell size of the foam plastic is 0.1 mm, the number of surface bubbles is 10 per m², the density distribution is uniform, the dimensional stability is good, the mechanical properties are excellent, the water resistance is good, and it can still maintain more than 95% of its mechanical properties after being soaked in water for 48 hours.

[0042] Experiment 2: Take the polysiloxane product prepared in Example 2, mix it with isocyanate black material at a mass ratio of 1:1.3, pour it into a mold, and carry out a foaming reaction. The reaction temperature is 75 °C, and the reaction time is 4 minutes. After the foaming reaction is completed, take out the foam plastic sample for performance testing. The test results show that the cell size of the foam plastic is 0.12 mm, the number of surface bubbles is 8 per m², the density distribution is uniform, the dimensional stability is good, the mechanical properties are excellent, the water resistance is good, and it can still maintain more than 96% of its mechanical properties after being soaked in water for 48 hours.

[0043] Experiment 3: Take the polysiloxane product prepared in Example 3, mix it with isocyanate black material according to a mass ratio of 1:1.4, pour it into a mold, and carry out a foaming reaction. The reaction temperature is 75 °C and the reaction time is 4 minutes. After the foaming reaction is completed, take out the foam plastic sample and conduct performance tests. The test results show that the cell size of the foam plastic is 0.1 mm, the number of surface bubbles is 12 per m², the density distribution is uniform, the dimensional stability is good, the mechanical properties are excellent, the water resistance is good, and it can still maintain more than 95% of the mechanical properties after being immersed in water for 48 hours.

[0044] From the above experimental results, it can be seen that the polysiloxane product prepared by the present invention exhibits excellent comprehensive performance during the reaction with isocyanate black material to prepare rigid polyurethane foam. The foam plastic has small cell size, few surface bubbles, uniform density distribution, good dimensional stability and mechanical properties, and significantly improved water resistance, and is suitable for the preparation of high-performance rigid polyurethane foam.

[0045] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims

1. A preparation method of a polyorganosiloxane, characterized in that, It includes the following steps: 1) Prepare materials by weight: 15 - 25 parts of cyclic siloxane; 3 - 8 parts of organosilane coupling agent; 10 - 18 parts of polyol; 6 - 15 parts of epichlorohydrin; 0.1 - 0.3 parts of acidic catalyst; 50 - 70 parts of propylene oxide; Put the cyclic siloxane, organosilane coupling agent and polyol into a reaction kettle, seal the kettle and heat for reaction; 2) Continuously dropwise add epichlorohydrin under heating. During the reaction, the temperature in the kettle is 110°C - 150°C, and the pressure in the kettle is 0.1 MPa - 0.5 MPa. After the dropwise addition is completed, continue the curing reaction for 2 h - 4 h, add the acidic catalyst, seal the kettle and carry out negative pressure replacement to remove oxygen; 3) Continuously dropwise add propylene oxide under heating. During the reaction, control the temperature in the kettle to be 120°C - 160°C, and the pressure in the kettle to be 0.1 MPa - 0.5 MPa. After the dropwise addition is completed, carry out the curing reaction for 2 h - 4 h to remove unreacted monomers; Lower the temperature in the kettle to 70°C - 90°C, add lye, water and activated clay under stirring and keep for 30 min - 60 min, raise the temperature to 110°C - 130°C and evacuate to dehydrate. Control the pressure in the kettle at -0.09 MPa - 0.07 MPa. When the detected moisture is lower than 0.1%, discharge the material and filter to obtain the polyorganosiloxane product; The organosilane coupling agent described above includes one or more of γ - glycidoxypropyltrimethoxysilane, γ - aminopropyltriethoxysilane, β - (3,4 - epoxycyclohexyl)ethyltrimethoxysilane.

2. The preparation method of the polysiloxane according to claim 1, characterized in that, The cyclic siloxane described above includes one or more of cyclotrisiloxane, cyclotetrasiloxane, cyclopentasiloxane, cyclohexasiloxane.

3. The preparation method of the polysiloxane according to claim 1, characterized in that, The polyol described above includes one or more of glycerol, sorbitol, pentaerythritol, ethylene glycol, diethylene glycol.

4. The preparation method of the polysiloxane according to claim 1, characterized in that, The acidic catalyst described above includes sulfuric acid.

5. The preparation method of the multi-component polysiloxane according to claim 1, characterized in that, The temperature of the heating reaction in step 1) is 110 - 150°C, and the time is 2 - 4 h.