Hollow polysiloxane particle and preparation method and application thereof

Abstract

The invention discloses a preparation method of hollow polysiloxane particles. The preparation method comprises the following steps: S1, preparing an oxygen-containing nonionic surfactant, water and polymer particles into a dispersion liquid; s2, mixing water with the first silicon source precursor to form a hydrolysate solution; s3, mixing the dispersion liquid and the hydrolysate solution, adding alkali liquor to enable the pH value of a final reaction system to be 8-11, generating first polysiloxane, and forming first particles; s4, performing heat treatment on the first particles in an inert gas atmosphere at 250-650 DEG C to form the hollow polysiloxane particles; wherein the alkali liquor is added into a reaction system at a constant speed within 0.5 min to 1 h. According to the preparation method disclosed by the invention, the formation speed of polysiloxane is controlled by selecting the addition amount, the addition speed and the addition sequence of the additive and the alkali liquor with specific types and dosages, so that the polysiloxane is prevented from self-polymerization, and the surface of the inner core is coated with the polysiloxane, so that the formation of solid small balls is avoided, and the yield of the hollow polysiloxane particles is improved; and the production cost of the hollow polysiloxane particles is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of polysiloxane particles, and particularly relates to a method for preparing hollow polysiloxane particles, the hollow polysiloxane particles prepared by this method, and the application of the particles. Background Art

[0002] Due to their low expansion coefficient and dielectric constant, hollow polysiloxane particles are widely used in the field of semiconductor device packaging. In the prior art, usually, a hydrolyzable organosiloxane is hydrolyzed and condensed to form a polysiloxide coating layer on the surface of the core microspheres, and then the core microspheres are removed by heat treatment to form hollow polysiloxane particles. However, during the polycondensation process, the formation rate of polysiloxane is too fast, resulting in the polysiloxane not being coated on the surface of the core microspheres but self-polymerizing to form solid small balls, thus leading to a low yield of hollow polysiloxane particles.

[0003] In order to reduce the preparation cost of hollow polysiloxane particles, improving the yield of hollow polysiloxane particles has become an urgent problem to be solved. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a method for preparing hollow polysiloxane particles and an application.

[0005] The present invention provides a method for preparing hollow polysiloxane particles, comprising: S1, preparing a dispersion liquid by mixing an oxygen-containing nonionic surfactant, water, and polymer particles; S2, mixing water and a first silicon source precursor to form a hydrolysis product solution; S3, after mixing the dispersion liquid and the hydrolysis product solution, adding an alkali solution to make the pH of the final reaction system 8 - 11 to generate a first polysiloxane, and the first polysiloxane coats the surface of the polymer particles to form a first particle; S4, heat-treating the first particle at 250 - 650°C in an inert gas atmosphere to form the hollow polysiloxane particles; wherein, in step S3, the alkali solution is added to the reaction system at a uniform speed within 0.5 min - 1 h.

[0006] According to an embodiment of the present invention, the oxygen-containing nonionic surfactant is polyvinylpyrrolidone, polyether P123, or polyether F127.

[0007] According to another embodiment of the present invention, the polymer particle material is one or more of polystyrene, polymethyl methacrylate, poly(methyl acrylate), phenol resin, melamine resin, polyurethane, and epoxy resin; and / or the particle size of the polymer particles is 80 nm - 9 μm.

[0008] According to another embodiment of the present invention, in the first mixed solution system, the mass ratio of the polymer particles, the oxygen-containing nonionic surfactant, and the total amount of water in steps S1 and S2 is 1: 0.1 to 0.01: 50 to 200; the mass ratio of the polymer particles to the first silicon source precursor is 1: 1 to 8.

[0009] According to another embodiment of the present invention, in step S3, the alkali solution is an aqueous ammonia solution with a mass concentration of 25% to 28%, a tetramethylammonium hydroxide solution with a mass concentration of 25% to 28%, a sodium hydroxide solution with a mass concentration of 1% to 10%, or a potassium hydroxide solution with a mass concentration of 1% to 10%.

[0010] According to another embodiment of the present invention, in the first polysiloxane, the molar content of the polysiloxane with a T unit in the main chain is more than 70%, and the T unit is R1SiO 3 / 2 , where R1 is a hydrocarbon group with 1 to 16 carbon atoms.

[0011] According to another embodiment of the present invention, the first silicon source precursor includes one or more of alkyltrialkoxysilanes and alkyltrichlorosilanes; preferably, it includes one or two of methyltrimethoxysilane and methyltrichlorosilane.

[0012] According to another embodiment of the present invention, after step S3 and before step S4, it further includes: adding a second silicon source precursor to the reaction system after forming the first particles in step S3; wherein, the mass ratio of the polymer particles to the second silicon source precursor is 1: 1 to 8, and the second silicon source precursor hydrolyzes to form a second polysiloxane coating on the outer surface of the first polysiloxane.

[0013] According to another embodiment of the present invention, in the second polysiloxane, the molar content of the polysiloxane with a T unit in the main chain is more than 70%.

[0014] According to another embodiment of the present invention, the second silicon source precursor includes one or more of alkyltrialkoxysilanes and alkyltrichlorosilanes; preferably, it includes one or two of methyltrimethoxysilane and methyltrichlorosilane.

[0015] According to another embodiment of the present invention, in step S4, the heat treatment is to heat up to 250 to 650 °C at a heating rate of 0.5 to 10 °C / min and hold for 3 to 20 h; the oxygen mass content in the inert gas atmosphere is less than 10%, and the flow rate of the inert gas is 30 to 1000 mL / min. Preferably, heat up to 450 to 650 °C.

[0016] The present invention also provides hollow polysiloxane particles prepared by the above preparation method.

[0017] The present invention further provides an application of the above-mentioned hollow polysiloxane particles in semiconductor packaging materials, substrate materials, supported catalysis, drug loading or cosmetics.

[0018] The preparation method of the hollow polysiloxane particles of the present invention controls the formation rate of polysiloxane by selecting specific types and amounts of additives in combination with the addition amount, addition rate and addition sequence of the alkali solution to avoid self-polymerization of polysiloxane, so that it is coated on the surface of the inner core, thereby avoiding the formation of solid spheres to improve the yield of hollow polysiloxane particles and reduce the production cost of hollow polysiloxane particles. Description of the Drawings

[0019] Figure 1 It is an enlarged schematic diagram for explaining the yield of hollow spheres.

[0020] Figure 2 It is a TEM photograph of the hollow polysiloxane particles prepared in Example 1.

[0021] Figure 3 It is a TEM photograph of the hollow polysiloxane particles prepared in Comparative Example 1.

[0022] Figure 4 It is an SEM photograph of the coated particles prepared in Comparative Example 2.

[0023] Figure 5 It is an SEM photograph of the polysiloxane particles prepared by heat-treating the coated particles prepared in Comparative Example 2. Detailed Embodiments

[0024] The present invention will be further described below in conjunction with embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are usually only a part of the embodiments of the present invention, rather than all the embodiments. Therefore, all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0025] The preparation method of the hollow polysiloxane particles of the present invention includes: S1, preparing a dispersion liquid by mixing an oxygen-containing nonionic surfactant, water and polymer particles; S2, mixing water and a first silicon source precursor to form a hydrolysis product solution; S3, after mixing the dispersion liquid and the hydrolysis product solution, adding an alkali solution to make the pH of the final reaction system 8-11 to generate a first polysiloxane, and the first polysiloxane coats the surface of the polymer particles to form a first particle; S4, heat-treating the first particle at 250-650°C in an inert gas atmosphere to form hollow polysiloxane particles; wherein, the adding speed of the alkali solution in step S3 is 20-200 mL / min. In the preparation method of the present invention, by selecting specific types and amounts of additives and coordinating with the addition amount, adding speed and adding order of the alkali solution to control the formation speed of the polysiloxane to avoid the self-polymerization of the polysiloxane, and making it coat on the surface of the inner core, so as to avoid the formation of solid small balls to improve the yield of the hollow polysiloxane particles and reduce the production cost of the hollow polysiloxane particles.

[0026] Specifically, in step S1, the oxygen-containing nonionic surfactant is easy to bond with the silicon source precursor due to containing oxygen (such as carbonyl, etc.), so that the polysiloxane formed by the hydrolysis of the silicon source precursor is more easily coated on the surface of the polymer particles. The oxygen-containing nonionic surfactant can be one or more of polyvinylpyrrolidone, polyether P123, and polyether F127.

[0027] The material of the polymer particles can be any suitable material that has no influence on the performance of the finally prepared hollow polysiloxane particles during the preparation process and can be removed by thermal decomposition. For example, the material of the polymer particles can be one or more of polystyrene, polymethyl methacrylate, polyacrylate methyl ester, phenol resin, melamine resin, polyurethane, and epoxy resin. The particle size of the polymer particles is 80 nm - 9 μm. The particle size of the polymer particles can be determined according to factors such as the hollow ratio and the average maximum diameter of the pre-prepared hollow polysiloxane particles. For example, but not limited to, the average maximum diameter of the particles can be 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, etc. The polymer particles can be any suitable shape, such as but not limited to spherical, cubic, polyhedral, ellipsoidal, etc.

[0028] In step S2, the first silicon source precursor is hydrolyzed. The appropriate stirring time can be selected according to the type of the first silicon source precursor to make the silicon source precursor hydrolyze sufficiently. For example, the stirring time can be 20-60 min. This process can be carried out at room temperature.

[0029] In an alternative embodiment, the mass ratio of the polymer particles, the oxygen-containing nonionic surfactant, and the total amount of water used in the S1 step and the S2 step is 1:0.1 to 0.01:50 to 200. The amount of water used in the S1 step and the S2 step respectively is such that the silicon source precursor can be fully hydrolyzed in the S2 step. In the preparation method of the present invention, if the content of the oxygen-containing nonionic surfactant is too low (i.e., the mass ratio of the polymer particles to the oxygen-containing nonionic surfactant is greater than 1:0.01, and the mass ratio of the oxygen-containing nonionic surfactant to water is less than 0.01:200), the content of the surfactant in water is too small, and then in the subsequent S3 step, the polysiloxane formed by the condensation of the hydrolysis product of the silicon source precursor is not easily coated on the surface of the polymer particles, so that a hollow structure cannot be formed; while if the content of the oxygen-containing nonionic surfactant is too high (i.e., the mass ratio of the polymer particles to the oxygen-containing nonionic surfactant is less than 1:0.1, and the mass ratio of the oxygen-containing nonionic surfactant to water is greater than 0.1:50), the content of the surfactant in water is too large, and then the viscosity of the aqueous solution is too high, and in the subsequent S3 step, the polysiloxane formed by the condensation of the hydrolysis product of the silicon source precursor is likely to agglomerate and cannot be completely coated on the surface of the polymer particles, so that a hollow structure cannot be formed.

[0030] In an alternative embodiment, the mass ratio of the polymer particles and the first silicon source precursor is 1:1 to 8. When the amount of the first silicon source precursor used is too small (i.e., the mass ratio of the polymer particles to the first silicon source precursor is greater than 1:1), the polysiloxane formed after the condensation of the hydrolysis product of the silicon source precursor is not sufficient to coat the polymer particles, so that a hollow structure cannot be formed; while when the amount of the first silicon source precursor used is too large (i.e., the mass ratio of the polymer particles to the first silicon source precursor is less than 1:8), the polysiloxane formed after the condensation of the hydrolysis product of the first silicon source precursor is too much, and self-aggregated polysiloxane spheres are likely to be formed in the system.

[0031] In step S3, after mixing the dispersion liquid with the hydrolysis product solution, an alkali solution is added to the solution to cause the hydrolysis product to condense to form polysiloxane, which coats the surface of the polymer particles. In this step, the amount of alkali added to the system is controlled by controlling the final pH value of the reaction system. If the amount of alkali added is too large (i.e., the final pH of the reaction system is greater than 11), the polysiloxane is likely to self-polymerize into small non-hollow-structured spheres. If the amount of alkali added is too small (i.e., the final pH of the reaction system is less than 8), the precursor hydrolysis is insufficient to form a gel state, resulting in a "jelly-like" appearance and the formation of a block structure instead of a hollow structure. In this step, the addition rate of the alkali solution is also controlled, and the alkali solution is added to the reaction system at a uniform rate within 0.5 min - 1 h. If the addition rate of the alkali solution is too large (i.e., the time for adding the alkali solution is less than 0.5 min), the polysiloxane is likely to self-polymerize into small non-hollow-structured spheres. If the addition rate of the alkali solution is too small (i.e., the time for adding the alkali solution is greater than 1 h), an uneven coating phenomenon occurs, i.e., a "snowman-like" structure, and finally a "bowl-like" structure is formed after heat treatment, and a closed hollow structure cannot be formed. The reaction time for this step can be between 1 and 10 h.

[0032] In an alternative embodiment, the alkali solution in this step can be an aqueous ammonia solution with a mass concentration of 25% - 28%, a tetramethylammonium hydroxide solution with a mass concentration of 25% - 28%, a sodium hydroxide solution with a mass concentration of 1% - 10%, or a potassium hydroxide solution with a mass concentration of 1% - 10%.

[0033] The preparation method of the present invention is applicable to hollow particles formed by polysiloxane with any unit (i.e., T unit, D unit, M unit, or a mixture thereof) in the main chain, and the yield is very high. In an alternative embodiment, the molar content of the polysiloxane with the T unit in the main chain in the first polysiloxane is more than 70%, and the T unit is R1SiO 3 / 2 , where R1 is a hydrocarbon group with 1 to 16 carbon atoms. The hollow polysiloxane particles with a molar content of more than 70% of the polysiloxane with the T unit in the main chain in the first polysiloxane have low water absorption performance and are more suitable as packaging materials for semiconductor devices. When the molar content of the polysiloxane with the T unit in the main chain in the first polysiloxane is less than 100%, other polysiloxanes can be polysiloxanes with the Q unit (SiO 4 / 2 ) and / or D unit (SiO 2 / 2 ) in the main chain. The molar content of the polysiloxane with the T unit in the main chain in the first polysiloxane can be selected as an appropriate value according to the application scenario of the hollow polysiloxane particles, such as, but not limited to, 70%, 75%, 85%, 85%, 90%, 95%, 100%, etc.

[0034] In an alternative embodiment, the first silicon source precursor includes one or more of hydrocarbyl trialkoxysilane and hydrocarbyl trichlorosilane. Preferably, the first silicon source precursor includes one or two of methyltrimethoxysilane and methyltrichlorosilane.

[0035] After the first particles are formed in step S3, a second silicon source precursor can also be added to the reaction system. In the reaction system, the second silicon source precursor hydrolyzes to form a second polysiloxane that coats the outer surface of the first polysiloxane. In an alternative embodiment, the mass ratio of the polymer particles to the second silicon source precursor is 1:1 to 8.

[0036] In an alternative embodiment, the molar content of the polysiloxane with a T-unit main chain in the second polysiloxane is above 70% to obtain hollow polysiloxane particles with low water absorption performance. Similarly, according to the application scenario of the hollow polysiloxane particles, an appropriate value can be selected for the molar content of the polysiloxane with a T-unit main chain in the second polysiloxane, such as but not limited to 70%, 75%, 85%, 85%, 90%, 95%, 100%, etc. The second silicon source precursor includes one or more of hydrocarbyl trialkoxysilane and hydrocarbyl trichlorosilane. Preferably, it includes one or two of methyltrimethoxysilane and methyltrichlorosilane.

[0037] In step S4, heat treatment is carried out in an inert gas atmosphere to carbonize the polymer particles. The inert gas atmosphere refers to an inert gas with an oxygen mass content below 10%, such as but not limited to nitrogen, air with an oxygen mass content less than 10%, etc. To avoid the phenomenon of particle breakage in this step, the temperature of the heat treatment is controlled at 250 - 650 °C and held for more than 3 hours, such as 3 - 20 h. Preferably, the heating rate of this step is 0.5 - 10 °C / min, and the flow rate of the inert gas is 30 - 1000 mL / min. More preferably, the heat treatment temperature is controlled between 450 - 650 °C. When the heat treatment temperature is within this range, the hydrocarbyl groups in the polysiloxane can be completely carbonized, and the prepared polysiloxane has a higher purity, so that the water absorption performance of the prepared hollow polysiloxane particles is lower.

[0038] The hollow polysiloxane particles prepared by the preparation method of the present invention can be used in semiconductor packaging materials, substrate materials, supported catalysis, drug loading, or cosmetics.

[0039] The present invention is further described below through specific examples. However, these examples are merely exemplary and do not constitute any limitation to the protection scope of the present invention. In the following examples and comparative examples, the reagents, materials, and instruments used can be obtained commercially without special instructions.

[0040] The characterization and testing methods involved in the following examples and comparative examples are as follows:

[0041] In the structural characterization, the hollow polysiloxane particles were characterized by a FEI Talos F200S transmission electron microscope (TEM). In the obtained TEM images, 20 hollow polysiloxane particles were randomly selected, and the total area of the hollow part and the total area of the powder were calculated using ImageJ software. The hollowness ratio was equal to the ratio of the area of the hollow part to the total area of the powder.

[0042] In the structural characterization, the yield of the hollow polysiloxane particles was characterized by using a FEI Talos F200S transmission electron microscope (TEM). In the obtained TEM images, 50 particles were randomly selected, and the yield of the hollow spheres was calculated by dividing the number of hollow particles by the total number of all particles. That is, as Figure 1 shown, the yield = the number of hollow particles / the total number of all particles, and the total number of all particles was 50.

[0043] In the structural characterization, the hollow polysiloxane particles were characterized by a FEI Talos F200S transmission electron microscope (TEM). In the obtained TEM images, 20 hollow polysiloxane particles were randomly selected, and the total area of the hollow part and the total area of the particles were calculated using ImageJ software. The hollowness ratio was equal to the ratio of the area of the hollow part to the total area of the powder.

[0044] The specific surface area was measured by a SHIMADZU FlowSorb III 2305.

[0045] In the performance test, the binding performance between the hollow polysiloxane particles and the resin was characterized by the "number of peeled particles bound to the resin". The test method for the "number of peeled particles bound to the resin" was as follows: The hollow polysiloxane particles were dispersed in the epoxy resin and heated for curing, then sliced and polished with an ion beam, and then the interface between the hollow polysiloxane particles and the resin was observed with an electron microscope. Randomly selected areas were counted, and the number of particles with peeling at the interface among 1000 particles was obtained, which was the number of peeled particles bound to the resin.

[0046] In the performance test, the fluidity of the mixture of the hollow polysiloxane particles and the resin was tested with a DHR rheometer. The test method was as follows: The hollow polysiloxane particles and the epoxy resin were uniformly mixed at a mass ratio of 7:3, and the mixture was dropped into a fixture with a gap of 350 μm. The viscosity value was measured at a rotation speed of 1 S at 25 °C. -1 The viscosity value was obtained through the test.

[0047] In the water content test, the water content of the particles was the moisture at 200 °C and was tested with a Karl Fischer moisture meter. The instrument was the CA-310 of Mitsubishi Chemical, and the determination method was the Coulometric method.

[0048] Example 1

[0049] Add 5000 g of water, 1 g of polyvinylpyrrolidone, and 100 g of polystyrene microspheres with a particle size of 600 nm into a reactor to prepare a uniform emulsion (step S1); add 5000 g of water and 400 g of methyltrimethoxysilane into another reactor, stir at 25 °C for 2 h for hydrolysis (step S2); then mix the polymer emulsion and the hydrolysis product solution, and then add 25% tetramethylammonium hydroxide solution thereto at a uniform speed. The addition time is 50 min, the final pH of the reaction system is 9, and react at 25 °C for 10 h. After washing and drying, polystyrene microsphere@polysiloxane core-shell composite is obtained (step S3);

[0050] Mix 100 g of polystyrene microsphere@polysiloxane core-shell composite with 5 g of acetylene black evenly and put it into a tubular furnace. Set the nitrogen flow rate to 300 mL / min. Under a nitrogen atmosphere, heat it to 550 °C at a rate of 1 °C / min and keep it warm for 8 h to obtain hollow polysiloxane particles (step S4).

[0051] Figure 2 The TEM photograph of the particles prepared in this example is shown. It can be seen from the photograph that the particles prepared in this example are of a hollow structure.

[0052] Example 2

[0053] Add 5000 g of water, 1 g of polyether F127, and 100 g of polystyrene microspheres with a particle size of 600 nm into a reactor to prepare a uniform emulsion (step S1); add 5000 g of water and 400 g of methyltrimethoxysilane into another reactor, stir at 25 °C for 2 h for hydrolysis (step S2); then mix the polymer emulsion and the hydrolysis product solution, and then add 25% tetramethylammonium hydroxide solution thereto at a uniform speed. The addition time is 50 min, the final pH of the reaction system is 11, and react at 25 °C for 10 h. After washing and drying, polystyrene microsphere@polysiloxane core-shell composite is obtained (step S3);

[0054] Mix 100 g of polystyrene microsphere@polysiloxane core-shell composite with 5 g of graphite evenly and put it into a tubular furnace. Set the nitrogen flow rate to 300 mL / min. Under a nitrogen atmosphere, heat it to 400 °C at a rate of 1 °C / min and keep it warm for 20 h to obtain hollow polysiloxane particles (step S4).

[0055] Example 3

[0056] Add 5000 g of water, 1 g of polyether P123, and 100 g of polystyrene microspheres with a particle size of 80 nm into a reactor to prepare a uniform emulsion (step S1); add 5000 g of water and 400 g of methyltrimethoxysilane into another reactor, stir at 25 °C for 2 h for hydrolysis (step S2); then mix the polymer emulsion and the hydrolysis product solution, and then add a 25% tetramethylammonium hydroxide solution thereto at a uniform rate. The addition time is 0.5 min, the final pH of the reaction system is 9.5, and react at 25 °C for 10 h. After washing and drying, polystyrene microsphere@polysiloxane core-shell composites are obtained (step S3);

[0057] Mix 100 g of polystyrene microsphere@polysiloxane core-shell composites with 100 g of acetylene black evenly and put them into a tube furnace. Set the nitrogen flow rate to 300 mL / min. Under a nitrogen atmosphere, heat to 400 °C at a rate of 1 °C / min and hold for 3 h to obtain hollow polysiloxane particles (step S4).

[0058] Example 4

[0059] Add 5000 g of water, 1 g of polyether F127, and 100 g of polystyrene microspheres with a particle size of 4.5 μm into a reactor to prepare a uniform emulsion (step S1); add 5000 g of water and 400 g of methyltrimethoxysilane into another reactor, stir at 25 °C for 2 h for hydrolysis (step S2); then mix the polymer emulsion and the hydrolysis product solution, and then add a 25% ammonia water solution thereto at a uniform rate. The addition time is 60 min, the final pH of the reaction system is 8, and react at 25 °C for 10 h. After washing and drying, polystyrene microsphere@polysiloxane core-shell composites are obtained (step S3);

[0060] Mix 100 g of polystyrene microsphere@polysiloxane core-shell composites with 400 g of acetylene black evenly and put them into a tube furnace. Set the nitrogen flow rate to 300 mL / min. Under a nitrogen atmosphere, heat to 650 °C at a rate of 1 °C / min and hold for 10 h to obtain hollow polysiloxane particles (step S4).

[0061] Example 5

[0062] Add 5000 g of water, 1 g of polyvinylpyrrolidone, and 100 g of polystyrene microspheres with a particle size of 1 μm into a reactor to prepare a uniform emulsion (step S1); add 5000 g of water and 300 g of methyltrimethoxysilane into another reactor, stir at 25 °C for 2 h for hydrolysis (step S2); then mix the polymer emulsion and the hydrolysis product solution, and then add 25% ammonia water thereto at a constant speed for 60 min. The final pH of the reaction system is 8.5, and react at 25 °C for 10 h. After washing and drying, polystyrene microsphere@polysiloxane core-shell composite is obtained (step S3);

[0063] Mix 100 g of polystyrene microsphere@polysiloxane core-shell composite with 10 g of graphite evenly and put it into a tube furnace. Set the nitrogen flow rate to 300 mL / min. Under a nitrogen atmosphere, heat it to 550 °C at a rate of 1 °C / min and keep it warm for 10 h to obtain hollow polysiloxane particles (step S4).

[0064] Example 6

[0065] Add 5000 g of water, 1 g of polyvinylpyrrolidone, and 100 g of polystyrene microspheres with a particle size of 1 μm into a reactor to prepare a uniform emulsion (step S1); add 5000 g of water and 300 g of methyltrimethoxysilane into another reactor, stir at 25 °C for 2 h for hydrolysis (step S2); then mix the polymer emulsion and the hydrolysis product solution, and then add 25% tetramethylammonium hydroxide solution thereto at a constant speed for 60 min. The final pH of the reaction system is 11, and react at 25 °C for 10 h. After washing and drying, polystyrene microsphere@polysiloxane core-shell composite is obtained (step S3);

[0066] Mix 100 g of polystyrene microsphere@polysiloxane core-shell composite with 10 g of graphite evenly and put it into a tube furnace. Set the nitrogen flow rate to 300 mL / min. Under a nitrogen atmosphere, heat it to 250 °C at a rate of 1 °C / min and keep it warm for 10 h to obtain hollow polysiloxane particles (step S4).

[0067] Example 7

[0068] Add 5000 g of water, 0.01 g of polyvinylpyrrolidone, and 100 g of polystyrene microspheres with a particle size of 1 μm into a reactor to prepare a uniform emulsion (step S1); add 5000 g of water, 210 g of methyltrimethoxysilane, and 90 g of dimethyldimethoxysilane into another reactor, stir at 25 °C for 2 h for hydrolysis (step S2); then mix the polymer emulsion and the hydrolysis product solution, and then add a 25% tetramethylammonium hydroxide solution thereto at a uniform rate. The addition time is 60 min, the final pH of the reaction system is 9.5, and react at 25 °C for 10 h. After washing and drying, polystyrene microsphere@polysiloxane core-shell composite is obtained (step S3);

[0069] Mix 100 g of polystyrene microsphere@polysiloxane core-shell composite with 10 g of graphite evenly and put it into a tubular furnace. Set the nitrogen flow rate to 300 mL / min. Under a nitrogen atmosphere, heat it to 550 °C at a rate of 1 °C / min and hold for 10 h to obtain hollow polysiloxane particles (step S4).

[0070] Example 8

[0071] Add 5000 g of water, 1 g of polyvinylpyrrolidone, and 100 g of polystyrene microspheres with a particle size of 1 μm into a reactor to prepare a uniform emulsion (step S1); add 5000 g of water, 270 g of methyltrimethoxysilane, 15 g of tetramethoxysilane, and 15 g of dimethyldimethoxysilane into another reactor, stir at 25 °C for 2 h for hydrolysis (step S2); then mix the polymer emulsion and the hydrolysis product solution, and then add a 25% tetramethylammonium hydroxide solution thereto at a uniform rate. The addition time is 60 min, the final pH of the reaction system is 8.5, and react at 25 °C for 10 h. After washing and drying, polystyrene microsphere@polysiloxane core-shell composite is obtained (step S3);

[0072] Mix 100 g of polystyrene microsphere@polysiloxane core-shell composite with 10 g of graphite evenly and put it into a tubular furnace. Set the nitrogen flow rate to 300 mL / min. Under a nitrogen atmosphere, heat it to 550 °C at a rate of 1 °C / min and hold for 10 h to obtain hollow polysiloxane particles (step S4).

[0073] Example 9

[0074] Add 5000 g of water, 1 g of polyvinylpyrrolidone, and 100 g of polystyrene microspheres with a particle size of 600 nm into a reactor to prepare a uniform emulsion (step S1); add 5000 g of water and 400 g of methyltrimethoxysilane into another reactor, stir at 25 °C for 2 h for hydrolysis (step S2); then mix the polymer emulsion and the hydrolysis product solution, and then add a 25% tetramethylammonium hydroxide solution thereto at a uniform speed. The addition time is 50 min, the final pH of the reaction system is 9, and react at 25 °C for 10 h (step S3); add 400 g of methyltrimethoxysilane to the reaction system and react at 25 °C for 2 h. After washing and drying, polystyrene microsphere@polysiloxane core-shell composites are obtained;

[0075] Mix 100 g of polystyrene microsphere@polysiloxane core-shell composites with 5 g of acetylene black evenly and put them into a tube furnace. Set the nitrogen flow rate to 300 mL / min. Under a nitrogen atmosphere, heat to 550 °C at a rate of 1 °C / min and hold for 8 h to obtain hollow polysiloxane particles (step S4).

[0076] Example 10

[0077] Add 5000 g of water, 1 g of polyvinylpyrrolidone, and 100 g of polystyrene microspheres with a particle size of 600 nm into a reactor to prepare a uniform emulsion (step S1); add 5000 g of water and 5200 g of methyltrimethoxysilane into another reactor, stir at 25 °C for 2 h for hydrolysis (step S2); then mix the polymer emulsion and the hydrolysis product solution, and then add a 25% tetramethylammonium hydroxide solution thereto at a uniform speed. The addition time is 50 min, react at 25 °C for 10 h, and after washing and drying, polystyrene microsphere@polysiloxane core-shell composites are obtained (step S3);

[0078] Mix 100 g of polystyrene microsphere@polysiloxane core-shell composites with 5 g of acetylene black evenly and put them into a tube furnace. Set the nitrogen flow rate to 300 mL / min. Under a nitrogen atmosphere, heat to 550 °C at a rate of 1 °C / min and hold for 8 h to obtain hollow polysiloxane particles (step S4).

[0079] Comparative Example 1

[0080] The difference from Example 1 is that: in step S3, the uniform addition time of the tetramethylammonium hydroxide solution is 0.33 min. Others are the same as in Example 1.

[0081] Figure 3 Show the TEM photo of the particles prepared in this comparative example. It can be seen from the photo that in the particles prepared in this comparative example, in addition to the hollow structure, a solid structure is also generated, resulting in a decrease in the yield of hollow particles.

[0082] Comparative Example 2

[0083] The difference from Example 1 is that: in step S3, the time for uniformly adding the tetramethylammonium hydroxide solution is 70 min. Others are the same as in Example 1.

[0084] Figure 4 The SEM photograph of the particles prepared in this comparative example is shown. It can be seen from the photograph that the particles prepared in this example show the phenomenon of non-uniform coating, that is, the "snowman-shaped" structure. Figure 5 It shows the particles with a "bowl-shaped" structure formed after the final heat treatment. Thus, it can be explained that when the addition rate of the alkali solution is too low, particles with a hollow structure cannot be formed either.

[0085] Comparative Example 3

[0086] The difference from Example 1 is that: in step S3, the final pH of the reaction system is 12. Others are the same as in Example 1.

[0087] Comparative Example 4

[0088] The difference from Example 1 is that: in step S3, the final pH of the reaction system is 7. Others are the same as in Example 1.

[0089] Comparative Example 5

[0090] The difference from Example 1 is that: in step S1, the surfactant is cetyltrimethylammonium bromide (CTAB). Others are the same as in Example 1.

[0091] Comparative Example 6

[0092] The difference from Example 1 is that: in step S2, the silicon source precursor is tetraethyl orthosilicate with the same molar amount. Others are the same as in Example 1. The hollow particles prepared in this comparative example are silica hollow particles.

[0093] The test data of the particles prepared in Examples 1-10 and Comparative Examples 1-5 are shown in Table 1.

[0094] Table 1

[0095]

[0096]

[0097] It can be seen from Example 1 and Comparative Example 1 that when the tetramethylammonium hydroxide solution is added to the reactor at 300 mL / min, more solid-structured particles will be generated in the system, resulting in a decrease in the yield of hollow particles; due to the presence of solid particles, the water content and specific surface area also decrease.

[0098] As can be seen from Example 1 and Comparative Example 2, when the tetramethylammonium hydroxide solution was added to the reactor at 15 mL / min, the prepared particles showed uneven coating, i.e., the "snowman-like" structure, and finally formed the "bowl-like" structure after heat treatment. Therefore, the yield and hollowness of the hollow particles were zero.

[0099] As can be seen from Example 1 and Comparative Example 3, when the pH of the reaction system was 12, more solid-structured particles were generated in the system, resulting in a decrease in the yield of hollow particles; due to the presence of solid particles, the water content and specific surface area also decreased.

[0100] As can be seen from Example 1 and Comparative Example 4, when the pH of the reaction system was 7, the precursor reaction was not sufficient, forming a gel state, resulting in a blocky structure of the coated material, so the data in the table could not be reflected.

[0101] As can be seen from Comparative Example 5, when the surfactant was cetyltrimethylammonium bromide (CTAB), the hollow particles agglomerated significantly and there were many self-aggregated particles, resulting in a decrease in the yield of hollow particles.

[0102] As can be seen from Example 1 and Comparative Example 6, when the silicon source precursor in Step S2 was tetraethyl orthosilicate with the same molar amount, the yield and hollowness of the hollow particles basically did not change, but the water content and specific surface area increased significantly.

[0103] As can be seen from Example 1 and Example 4, the larger the particle size, the lower the specific surface area, the lower the water content, the higher the number of peeled particles combined with the resin, and the lower the viscosity.

[0104] From Examples 1 and 2, Examples 5 and 6, it can be seen that under the condition of the same particle size, the water absorption performance of the hollow polysiloxane particles prepared at a heat treatment temperature of 450 - 650 °C was lower.

[0105] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for preparing hollow polysiloxane particles, characterized in that: include: S1, preparing a dispersion liquid by using an oxygen-containing nonionic surfactant, water and polymer particles; S2, mixing water and the first silicon source precursor to form a hydrolyzate solution; S3, after mixing the dispersion and the hydrolysis product solution, adding an alkali solution so that the final pH of the reaction system is 8 to 11, generating a first polysiloxane, wherein the first polysiloxane is coated on the surface of the polymer particles to form first particles; S4, heat-treating the first particles at 250-650° C. in an inert gas atmosphere to form the hollow polysiloxane particles; Wherein, the alkali solution in the step S3 is added to the reaction system at a uniform speed within 0.5min-1h.

2. The preparation method according to claim 1, characterized in that: The oxygen-containing nonionic surfactant is polyvinyl pyrrolidone, polyether P123, and polyether F127.

3. The preparation method according to claim 1, characterized in that: The polymer particles are made of one or more of polystyrene, polymethyl methacrylate, polymethyl acrylate, phenol resin, melamine resin, polyurethane, and epoxy resin; and / or The particle size of the polymer particles is 80 nm to 9 μm.

4. The preparation method according to claim 1, characterized in that: In the first mixed solution system, the mass ratio of the polymer particles, the oxygen-containing nonionic surfactant and the total amount of water used in the steps S1 and S2 is 1:0.1-0.01:50-200; The mass ratio of the polymer particles to the first silicon source precursor is 1:1-8.

5. The preparation method according to claim 1, characterized in that: In the step S3, the alkali solution is an ammonia solution with a mass concentration of 25% to 28%, a tetramethylammonium hydroxide solution with a mass concentration of 25% to 28%, a sodium hydroxide solution with a mass concentration of 1% to 10%, or a potassium hydroxide solution with a mass concentration of 1% to 10%.

6. The preparation method according to claim 1, characterized in that: The molar content of polysiloxane with T units as the main chain in the first polysiloxane is more than 70%, and the T units are R1SiO 3 / 2 , R1 is a hydrocarbon group having 1 to 16 carbon atoms.

7. The preparation method according to claim 1, characterized in that: The first silicon source precursor includes one or more of hydrocarbon trialkoxysilane and hydrocarbon trichlorosilane; preferably, includes one or two of methyltrimethoxysilane and methyltrichlorosilane.

8. The preparation method according to claim 1, characterized in that: After the step S3 and before the step S4, the method further includes: adding a second silicon source precursor to the reaction system after the first particles are formed in the step S3; The mass ratio of the polymer particles to the second silicon source precursor is 1:1-8, and the second silicon source precursor is hydrolyzed to form a second polysiloxane that is coated on the outer surface of the first polysiloxane.

9. The preparation method according to claim 8, characterized in that: The molar content of polysiloxane with T units as the main chain in the second polysiloxane is greater than 70%.

10. The preparation method according to claim 8, characterized in that: The second silicon source precursor includes one or more of hydrocarbon trialkoxysilane and hydrocarbon trichlorosilane; preferably, includes one or two of methyltrimethoxysilane and methyltrichlorosilane.

11. The preparation method according to claim 1, characterized in that: In the step S4, the heat treatment is performed by heating the temperature to 250-650°C at a heating rate of 0.5-10°C / min and keeping the temperature for 3-20h; preferably, the temperature is raised to 450-650°C; The oxygen mass content in the inert gas atmosphere is less than 10%, and the flow rate of the inert gas is 30-1000 mL / min.

12. A hollow polysiloxane particle, characterized in that: Prepared by the preparation method described in any one of claims 1 to 11.

13. Use of the hollow polysiloxane particles according to claim 12 as semiconductor packaging materials, substrate materials, supported catalysis, drug loading or cosmetics.

Images