Preparation method of polyvinyl methyl silsesquioxane

Abstract

The invention discloses a preparation method of polyvinyl methyl silsesquioxane, and belongs to the technical field of organic silicon material preparation. The method comprises the following steps: adding a mixture of methyltrimethoxysilane and vinyltrimethoxysilane with the pH value of 4-5 into pure water, heating for hydrolysis, then heating, adding a basic catalyst for condensation polymerization, and finally carrying out solid-liquid separation, drying and crushing to obtain the regular spherical polyvinyl methyl silsesquioxane with the surface containing vinyl reactive groups. The preparation method does not need to use an organic solvent, the product yield is high (greater than 98%), the prepared product is regular spherical, the average particle size is 0.5-15 [mu] m, the particle size distribution is narrow (the width is less than 1.2), the surface contains reactive vinyl, and the product can be stably combined with a matrix, is suitable for the fields of coatings, printing ink, cosmetics and the like, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of organic polymer material preparation, specifically relating to a method for preparing polyvinylmethylsilsesquioxane. Background Technology

[0002] Silsesquioxane microspheres have been widely used in coatings, inks, cosmetics, and other fields due to their excellent heat resistance, weather resistance, and mechanical properties. In the prior art, for example, patent publication number CN103087319A discloses a copolymerized silsesquioxane microsphere and its preparation method, in which polysilsesquioxane microspheres are obtained by reacting two siloxane monomers with different structures in an inert solvent in the presence of an alkaline catalyst.

[0003] However, the surface of polysilsesquioxane microspheres synthesized using existing technologies typically consists of non-reactive stable groups such as methyl and phenyl groups. When used in high-level applications in coatings, inks, and cosmetics, this can easily lead to weak bonding between the microspheres and the matrix, resulting in phenomena such as powdering and whitening, thus affecting product performance. Furthermore, existing technologies often rely on organic solvents, which not only increases production costs but also poses environmental pollution risks.

[0004] Therefore, developing a method for preparing silsesquioxanes that does not require organic solvents, produces microspheres with reactive groups that can stably bind to the matrix, and has advantages such as controllable particle size, good sphericity, and high yield has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing polyvinylmethylsilsesquioxane without the use of organic solvents. The prepared polyvinylmethylsilsesquioxane microspheres have reactive groups, can be stably combined with the matrix, and have controllable particle size, good sphericity, narrow particle size distribution, and high product yield.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for preparing polyvinylmethylsilsesquioxane includes the following steps: (1) Add a mixture of silane monomers with a pH of 4 to 5 to pure water, wherein the mixture of silane monomers includes methyltrimethoxysilane and vinyltrimethoxysilane; (2) The temperature is increased to 40-55℃ at a heating rate of 0.5-4℃ / min, and the mixture is stirred to carry out the silane hydrolysis reaction; (3) After the hydrolysis reaction is completed, the temperature is increased to 55-65°C at a heating rate of 0.5-4°C / min, an alkaline catalyst is added, and stirring is stopped after 10-100 seconds. The mixture is kept warm and allowed to stand for 1-8 hours for polycondensation reaction. (4) After the polycondensation reaction is completed, solid-liquid separation, drying and pulverization are carried out to obtain polyvinylmethylsilsesquioxane product.

[0007] As a further description of the above technical solution: the mass ratio of the silane monomer mixture to water in step (1) is 1:(3~10), which can ensure that the silane monomer is fully dispersed in water and completes the hydrolysis reaction, laying the foundation for subsequent polycondensation to form regular spherical shapes, and can also avoid incomplete reaction due to insufficient water or increased subsequent separation and processing costs due to excessive water. At the same time, under the premise of ensuring high product yield and narrow particle size distribution, the environmental protection and economy of the process are further improved, making it suitable for industrial production.

[0008] As a further description of the above technical solution: the mass ratio of methyltrimethoxysilane and vinyltrimethoxysilane in step (1) is (60-90):(10-40). By introducing reactive vinyl groups with an appropriate amount of vinyltrimethoxysilane, the product is ensured to be stably bonded to the matrix, solving the problems of powdering and whitening when the addition amount is high in the prior art. At the same time, the stability and hydrophobicity of silsesquioxane can be maintained by the higher proportion of methyltrimethoxysilane, avoiding excessive cross-linking or agglomeration caused by too many reactive groups. At the same time, it is compatible with subsequent hydrolysis and polycondensation processes, and can stably prepare products with controllable particle size, high sphericity and narrow particle size distribution.

[0009] As a further description of the above technical solution: the alkaline catalyst in step (3) is tetramethylammonium hydroxide, and the amount of alkaline catalyst added is 0.5-5% of the total weight of the silane monomer mixture. As a highly efficient alkaline catalyst, tetramethylammonium hydroxide can effectively promote the polycondensation reaction of the hydrolyzed products. The appropriate amount ensures catalytic activity, promotes the full polycondensation to form a regular spherical structure, and avoids side reactions or adverse effects on product performance caused by excessive amount. At the same time, tetramethylammonium hydroxide is easily soluble in water, can be quickly dispersed and play a role, and with specific heating and standing conditions, further ensures the stability of product quality.

[0010] As a further description of the above technical solution: the alkaline catalyst is prepared into a solution with a mass fraction of 5% to 10% using ultrapure water before addition. The use of ultrapure water for preparation avoids the introduction of impurities and ensures the purity of the catalyst. The concentration of the catalyst ensures that it is rapidly and uniformly dispersed after being added to the reaction system, ensuring that the polycondensation reaction proceeds synchronously and efficiently within the system. This avoids side reactions caused by excessively high local catalyst concentrations or uneven product morphology, providing a guarantee for the formation of products with controllable particle size, high sphericity, and narrow particle size distribution, further improving process stability and product yield.

[0011] As a further description of the above technical solution: the drying in step (4) is carried out at a temperature of 60-80℃ and a negative pressure of 0.3-0.6 MPa, which can not only efficiently evaporate moisture, but also avoid product structure damage due to excessive temperature (such as the instability of vinyl groups when heated), and ensure the integrity of microsphere morphology; the negative pressure environment can shorten the drying time and also avoid possible microsphere agglomeration, and stably maintain the regular spherical shape of the product.

[0012] As a further description of the above technical solution: the pulverizing speed in step (4) is 400-800 rpm / min, and the pulverizing time is 3-8 minutes. Using medium-low speed pulverization can avoid excessive impact caused by high-speed pulverization, which may lead to damage to the microsphere structure or a decrease in sphericity. At the same time, it can effectively disperse the slight agglomerates that may form after drying. The pulverizing time of 3-8 minutes can ensure that the particle size of the product is uniformly controlled within the target range of 0.5-15μm, and can also avoid excessive fineness of the particle size due to excessive time.

[0013] The present invention also provides a polyvinylmethylsilsesquioxane, which is prepared by the above preparation method, has vinyl reactive groups on its surface, an average particle size of 0.5-15 μm, and a sphericity >96%.

[0014] Compared with the prior art, the beneficial effects of the present invention are: The preparation method of polyvinylmethylsilsesquioxane of the present invention does not require the use of organic solvents, making it more environmentally friendly. The prepared polyvinylmethylsilsesquioxane contains vinyl reactive groups, which can stably bind with the matrix, effectively solving the problems of powdering and whitening at high addition levels. Furthermore, the process is simple, easy to operate, and has a high yield (>98%), making it easy for industrial production. The obtained polyvinylmethylsilsesquioxane has high sphericity (greater than 96%), controllable particle size (0.5–15 μm), and narrow particle size distribution (width less than 1.2), making it suitable for various fields such as coatings, inks, and cosmetics. Attached Figure Description

[0015] Figure 1 This is an electron microscope image (magnified 2000x) of the polyvinylmethylsilsesquioxane prepared in Example 1.

[0016] Figure 2 This is a particle size distribution curve of the polyvinylmethylsilsesquioxane prepared in Example 1. Detailed Implementation

[0017] The claims of the present invention will be further described in detail below with reference to specific embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of protection of the claims of the present invention are still within the scope of protection of the claims of the present invention.

[0018] Example 1 This embodiment provides a method for preparing polyvinylmethylsilsesquioxane, including the following steps: (1) Mix vinyltrimethoxysilane and methyltrimethoxysilane at a mass ratio of 10:90, adjust the pH of the mixture to 4-5, and obtain a silane monomer mixture; add the silane monomer mixture and pure water to the reaction vessel at a mass ratio of 1:3; (2) The mixture was heated from room temperature to 40°C at a rate of 0.5°C / min and stirred at a rate of 50 rpm / min for 1 hour for hydrolysis reaction; (3) After hydrolysis, continue to heat to 55°C at a rate of 0.5°C / min, add 0.5% of the total weight of the silane monomer mixture of tetramethylammonium hydroxide solution (prepared with ultrapure water, mass fraction of 5%), stir for 10 seconds and then turn off the stirring, keep warm and let stand for 8 hours for polycondensation reaction; (4) After the polycondensation reaction is completed, the solid product is separated by filtration and dried at 60°C and 0.3MPa negative pressure for 6 hours. Then it is pulverized in a pulverizer at 400rpm / min for 8 minutes to obtain polyvinylmethylsilsesquioxane product (yield 98.2%).

[0019] Its electron microscope images are as follows Figure 1 ,from Figure 1 It can be clearly observed that the polyvinylmethylsilsesquioxane microspheres are independently and regularly spherical (sphericity > 96.5%), with smooth surfaces, uniform morphology, and no obvious adhesion or deformation. Figure 2 The particle size distribution curve shows that the particle size is mainly distributed in the range of 3 to 8 μm, with an average particle size d(50) of 4.49 μm and a relatively narrow particle size distribution (width of about 0.87).

[0020] Example 2 This embodiment provides a method for preparing polyvinylmethylsilsesquioxane, including the following steps: (1) Mix vinyltrimethoxysilane and methyltrimethoxysilane at a mass ratio of 25:75, adjust the pH of the mixture to 4-5, and obtain a silane monomer mixture; add the silane monomer mixture and pure water to the reaction vessel at a mass ratio of 1:6; (2) The mixture was heated from room temperature to 48°C at a rate of 2°C / min and stirred at a rate of 35 rpm / min for 3 hours for hydrolysis reaction; (3) After hydrolysis, continue to heat to 60°C at a rate of 2°C / min, add 3% of the total weight of tetramethylammonium hydroxide solution (prepared with ultrapure water, mass fraction of 8%), stir for 50 seconds and then turn off the stirring, keep warm and let stand for 4 hours for polycondensation reaction. (4) After the polycondensation reaction is completed, the solid product is separated by filtration and dried at 70°C and 0.45 MPa negative pressure for 4 hours. Then it is pulverized in a pulverizer at 600 rpm / min for 3 minutes to obtain polyvinylmethylsilsesquioxane product with a yield of 98.8%.

[0021] The product was tested and found to be a regular sphere with a sphericity of 97.3%. The particle size was mainly distributed between 9.64 and 14.86 μm, with an average particle size of 12.15 μm and a particle size distribution width of 1.15.

[0022] Example 3 This embodiment provides a method for preparing polyvinylmethylsilsesquioxane, including the following steps: (1) Mix vinyltrimethoxysilane and methyltrimethoxysilane at a mass ratio of 40:60, adjust the pH of the mixture to 4-5, and obtain a silane monomer mixture; add the silane monomer mixture and pure water to the reaction vessel at a mass ratio of 1:10; (2) The mixture was heated from room temperature to 55°C at a rate of 4°C / min and stirred at a rate of 50 rpm / min for 1 hour for hydrolysis reaction; (3) After hydrolysis, continue to heat to 65°C at a rate of 4°C / min, add 5% of the total weight of tetramethylammonium hydroxide solution (prepared with ultrapure water, mass fraction of 10%), stir for 100 seconds and then turn off the stirring, keep warm and let stand for 1 hour for polycondensation reaction. (4) After the polycondensation reaction is completed, the solid product is separated by filtration and dried at 80°C and 0.6MPa negative pressure for 2 hours. Then it is pulverized in a pulverizer at 800 rpm / min for 5 minutes to obtain polyvinylmethylsilsesquioxane product with a yield of 96.8%.

[0023] The product was tested and found to be a regular sphere with a sphericity of 96.8%. The particle size was mainly distributed between 0.58 and 5.62 μm, with an average particle size of 3.26 μm and a particle size distribution width of 0.97.

[0024] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the present invention.

Claims

1. A method for preparing polyvinylmethylsilsesquioxane, characterized in that, Includes the following steps: (1) Add a mixture of silane monomers with a pH of 4 to 5 to pure water, wherein the mixture of silane monomers includes methyltrimethoxysilane and vinyltrimethoxysilane; (2) Heat the mixture to 40-55°C at a heating rate of 0.5-4°C / min and stir to carry out the silane hydrolysis reaction; (3) After the hydrolysis reaction is completed, the temperature is increased to 55-65℃ at a heating rate of 0.5-4℃ / min, an alkaline catalyst is added, and stirring is stopped after 10-100 seconds. The mixture is kept at the temperature and allowed to stand for 1-8 hours for polycondensation reaction. (4) After the polycondensation reaction is completed, solid-liquid separation, drying and pulverization are carried out to obtain polyvinylmethylsilsesquioxane product.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the silane monomer mixture to water in step (1) is 1:(3-10).

3. The preparation method according to claim 2, characterized in that: The mass ratio of methyltrimethoxysilane to vinyltrimethoxysilane in step (1) is (60-90):(10-40).

4. The preparation method according to claim 1, characterized in that: The alkaline catalyst mentioned in step (3) is tetramethylammonium hydroxide, and the amount of alkaline catalyst added is 0.5 to 5% of the total weight of the silane monomer mixture.

5. The preparation method according to claim 4, characterized in that: The alkaline catalyst is prepared into a solution with a mass fraction of 5% to 10% using ultrapure water before being added.

6. The preparation method according to claim 1, characterized in that: The drying process described in step (4) is carried out at a temperature of 60–80°C and a negative pressure of 0.3–0.6 MPa.

7. The preparation method according to claim 1, characterized in that: The grinding speed in step (4) is 400-800 rpm / min, and the grinding time is 3-8 minutes.

8. A polyvinylmethylsilsesquioxane, characterized in that: Prepared by the preparation method according to any one of claims 1-7, the surface contains vinyl reactive groups and the average particle size is 0.5-15 μm.

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