Modified hollow porous silica microspheres, and preparation method and application thereof

Abstract

The application provides a modified hollow porous silica microsphere and a preparation method and application thereof. The preparation method of the modified hollow porous silica microsphere comprises the following steps: S1, mixing a pre-hydrolysis solution of orthosilicate, a pre-hydrolysis solution of alkyl trialkoxysilane, a pre-hydrolysis solution of 1,2-bis(trialkoxysilyl)ethane and a polyol to obtain a mixture, refluxing, removing alcohol and obtaining a prepolymer; S2, mixing the prepolymer obtained in the step S1 with water, emulsifying, adjusting pH to alkaline, aging, filtering and drying, and the modified hollow porous silica microsphere is obtained. The application uses 1,2-bis(trialkoxysilyl)ethane as one of main silicon sources, and uses the mode of pre-hydrolyzing different silanes separately and then mixing and condensing, so that the highly hydrolyzable and polymerizable silane is prevented from being highly hydrolyzed and polymerized and the non-hydrolyzable and polymerizable silane is prevented from being hydrolyzed and polymerized, the preparation process is simple, the raw material cost is low, the porous microspheres obtained have good morphology and high yield, the operation condition is mild, and the application is easy to industrialize.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silica microsphere synthesis, and more particularly to a modified hollow porous silica microsphere, a preparation method therefor and an application thereof. BACKGROUND

[0002] Porous silica is a special structural material with a permeable silicon shell structure and a huge internal cavity in the shell. The porous silica microsphere has the characteristics of a large internal space, good stability, a large specific surface area, easy control of size and composition, and excellent permeability, and has broad application prospects in the fields of catalysis, adsorption and separation, drug loading and controlled release, and nanofabrication. According to the definition of the International Union of Pure and Applied Chemistry (IUPAC), porous materials can be divided into microporous (pore size < 2 nm), mesoporous (pore size 2-50 nm), and macroporous (pore size 50 nm-1 μm) materials according to the size of the pore size.

[0003] At present, there are various synthesis methods for porous silica microspheres, and the obtained products have different structures and pore sizes, but basically, the soft template method and the hard template method are adopted. In the hard template method, a polymer microsphere synthesized in advance is used as a template, and a silica precursor is deposited and grown on the surface of the polymer to obtain a silica composite microsphere. However, the polymer template needs to be calcined or dissolved in a solvent to obtain a mesoporous silica microsphere. In the process of removing the polymer template, the agglomeration of the mesoporous silica microsphere is increased, and even the shell is broken. In the soft template method, a microemulsion droplet is used as a template, and a large amount of surfactant needs to be introduced. Chemical reactions such as polymerization, hydrolysis, and sol-gel occur at the interface of the two phases to form a film. Finally, the porous silica microsphere is obtained by separation and drying. However, the soft template and all the surfactant molecules in the system need to be removed, and the preparation process is complex.

[0004] In addition, there is an emulsion polymerization method for preparing porous silica microspheres. For example, a method for preparing porous silica microspheres is disclosed in the prior art. A silica precursor, a hydrophobic solvent, and a co-stabilizer are mixed to obtain a uniform oil phase. The oil phase is mixed with an aqueous phase to obtain an emulsion, and a catalyst is added to obtain a silica microsphere. However, the shell layer of the silica microsphere prepared by this method contains only mesoporous voids, and the size is only at the nanometer level. Moreover, the hydrophilicity and hydrophobicity of the silica microsphere cannot be controlled, which limits its application. SUMMARY

[0005] In order to solve or at least partially solve the problems in the prior art, the present application provides a modified hollow porous silica microsphere, a preparation method therefor and an application thereof. The size of the modified hollow porous silica microsphere obtained by the preparation method provided by the present application is in the micron level, and the silica microsphere provided by the present application is in a hollow state.

[0006] The application provides a preparation method of modified hollow porous silica microspheres.

[0007] S1, mixing a pre-hydrolysis solution of orthosilicate, a pre-hydrolysis solution of alkyl trialkoxysilane, a pre-hydrolysis solution of 1,2-bis(trialkoxysilyl)ethane and a polyol to obtain a mixture, refluxing and reacting, and removing alcohol to obtain a prepolymer;

[0008] S2, mixing the prepolymer obtained in step S1 with water, emulsifying, adjusting pH to alkaline, aging, taking solid, and drying to obtain the modified hollow porous silica microspheres.

[0009] The application uses 1,2-bis(trialkoxysilyl)ethane, a by-product of vinyl trialkoxysilane synthesis and having low economic value, as one of main silicon sources, and uses the method of pre-hydrolyzing different silanes separately and then mixing and condensing, so that the highly hydrolyzable and polymerizable silane is prevented from being highly hydrolyzed and polymerized and the non-hydrolyzable and polymerizable silane is prevented from being non-hydrolyzed and polymerized, thereby preventing the prepolymer from being prepared or the modification from failing. The microspheres prepared by the preparation method have good appearance and high yield, and the microspheres prepared by the preparation method have good heat insulation performance.

[0010] In a preferred embodiment of the application, the preparation method of the pre-hydrolysis solution of orthosilicate comprises the following steps:

[0011] The orthosilicate is mixed with a first alcohol to obtain an orthosilicate alcohol mixture, a mixture of water and a second alcohol is added dropwise into the orthosilicate alcohol mixture, and the reaction is performed at the refluxing temperature of alcohol for 2-3 h, and then the temperature is lowered to obtain the pre-hydrolysis solution of orthosilicate; an acidity regulator is used to adjust the pH of the water to 2-3; the first alcohol and the second alcohol are saturated alcohols corresponding to siloxy functional groups in the orthosilicate.

[0012] In a preferred embodiment of the application, the orthosilicate is one or more of methyl orthosilicate, ethyl orthosilicate and butyl orthosilicate, and preferably ethyl orthosilicate. The microspheres prepared by using ethyl orthosilicate as the orthosilicate of the application have good morphology, appearance and structural stability. In a preferred embodiment of the application, in the preparation method of the pre-hydrolysis solution of orthosilicate, the amount of the first alcohol is preferably 10%-20% of the mass of the orthosilicate, and the amount of the second alcohol is preferably 50%-150% of the mass of the water. The molar amount of the water is preferably 0.9-1.3 times, and further preferably 1.0-1.15 times, the molar amount of the orthosilicate.

[0013] In the embodiment of the present application, in the preparation method of the orthosilicate pre-hydrolysate, the first alcohol and the second alcohol are both saturated alcohols corresponding to the siloxy functional groups in the orthosilicate. In a preferred embodiment of the present application, if the orthosilicate is ethyl orthosilicate, the saturated alcohol corresponding to the silylethoxy group is ethanol, i.e. in the preparation method of the orthosilicate pre-hydrolysate, the first alcohol and the second alcohol are both ethanol.

[0014] In a preferred embodiment of the present application, the preparation method of the alkyltrialkoxysilane pre-hydrolysate comprises the following steps:

[0015] The alkyltrialkoxysilane is mixed with the first alcohol to obtain an alkyltrialkoxysilane alcohol mixture, and the mixture of water and the second alcohol is added dropwise into the alkyltrialkoxysilane alcohol mixture, and the reaction is carried out at the alcohol refluxing temperature for 2-3 hours, and then the temperature is lowered to obtain the product; the pH of the water is adjusted to 2-3 using an acidity regulator; the first alcohol and the second alcohol are saturated alcohols corresponding to the siloxy functional groups in the alkyltrialkoxysilane.

[0016] In a preferred embodiment of the present application, the alkyltrialkoxysilane is methyltrialkoxysilane, propyltrialkoxysilane, hexyltrialkoxysilane or octyltrialkoxysilane, and in order to further improve the morphology and structure stability of the obtained microspheres, the alkyltrialkoxysilane is further preferably propyltriethoxysilane. In a preferred embodiment of the present application, in the preparation method of the alkyltrialkoxysilane pre-hydrolysate, the amount of the first alcohol is preferably 10%-20% of the mass of the alkyltrialkoxysilane, and the amount of the second alcohol is preferably 50%-150% of the mass of the water. The molar amount of the water is preferably 0.5-1.0 times, and further preferably 0.7-0.8 times the molar amount of the alkyltrialkoxysilane.

[0017] In the embodiment of the present application, in the preparation method of the alkyltrialkoxysilane pre-hydrolysate, the first alcohol and the second alcohol are both saturated alcohols corresponding to the siloxy functional groups in the alkyltrialkoxysilane. In a preferred embodiment of the present application, if the alkyltrialkoxysilane is propyltriethoxysilane, the saturated alcohol corresponding to the silylethoxy group is ethanol, i.e. in the preparation method of the alkyltrialkoxysilane pre-hydrolysate, the first alcohol and the second alcohol are both ethanol.

[0018] In a preferred embodiment of the present application, the preparation method of the 1,2-bis(trialkoxysilyl)ethane pre-hydrolysate comprises the following steps:

[0019] The 1,2-bis(trialkoxysilyl)ethane is mixed with a first alcohol to obtain a 1,2-bis(trialkoxysilyl)ethane alcohol mixture, and a mixture of water and a second alcohol is added dropwise to the 1,2-bis(trialkoxysilyl)ethane alcohol mixture, and the reaction is carried out at the reflux temperature of the alcohol for 2-3 hours, and then the temperature is lowered to obtain the pre-hydrolysis solution; the pH of the water is adjusted to 2-3 using an acidity regulator; the first alcohol and the second alcohol are saturated alcohols corresponding to the siloxy functional groups in the 1,2-bis(trialkoxysilyl)ethane.

[0020] In a preferred embodiment of the present application, the 1,2-bis(trialkoxysilyl)ethane is 1,2-bis(trimethoxysilyl)ethane or 1,2-bis(triethoxysilyl)ethane, and preferably 1,2-bis(triethoxysilyl)ethane. In a preferred embodiment of the present application, in the preparation method of the 1,2-bis(trialkoxysilyl)ethane pre-hydrolysis solution, the amount of the first alcohol is preferably 10%-20% of the mass of the 1,2-bis(trialkoxysilyl)ethane, and the amount of the second alcohol is preferably 50%-150% of the mass of the water. The molar amount of the water is preferably 1.0-2.0 times, and further preferably 1.3-1.6 times the molar amount of the 1,2-bis(trialkoxysilyl)ethane.

[0021] In a preferred embodiment of the present application, in the preparation method of the 1,2-bis(trialkoxysilyl)ethane pre-hydrolysis solution, the first alcohol and the second alcohol are both saturated alcohols corresponding to the siloxy functional groups in the 1,2-bis(trialkoxysilyl)ethane. In a preferred embodiment of the present application, if the 1,2-bis(trialkoxysilyl)ethane is bis(triethoxysilyl)ethane, the saturated alcohol corresponding to the triethoxysilyl group is ethanol, i.e., in the preparation method of the 1,2-bis(trialkoxysilyl)ethane pre-hydrolysis solution, the first alcohol and the second alcohol are both ethanol.

[0022] In the above preparation method of the pre-hydrolysis solution, the acidity regulator can be a commonly used acidity regulator such as hydrochloric acid. In order to further improve the stability of the obtained microspheres, the acidity regulator is preferably hydrochloric acid. The dropping temperature is room temperature, such as 25°C, etc.

[0023] In a preferred embodiment of the present application, in order to further improve the heat preservation performance of the obtained silica microspheres, in step S1, the molar ratio of silicon atoms in the orthosilicate pre-hydrolysis solution, silicon atoms in the alkyltrialkoxysilane pre-hydrolysis solution, and silicon atoms in the 1,2-bis(trialkoxysilyl)ethane pre-hydrolysis solution is 1:(0.02-0.6):(0.1-3), and preferably 1:(0.1-0.3):(0.4-1.3).

[0024] In a preferred embodiment of the present application, in step S1, the polyol is PPG with a molecular weight of 200-1000, preferably PPG with a molecular weight of 400. The applicant of the present application has found that the use of PPG 400 polyol results in microspheres with high sphericity, high internal porosity, high mechanical strength, less breakage and good integrity.

[0025] In a preferred embodiment of the present application, in order to further improve the structural strength of the microspheres and ensure the appearance of the microspheres, the amount of the polyol is 0.5%-2% of the total weight of the orthosilicate pre-hydrolyzate, the alkyl trialkoxysilane pre-hydrolyzate and the 1,2-bis(trialkoxysilyl)ethane pre-hydrolyzate.

[0026] In the present application, unless otherwise specified, "%" is mass percentage.

[0027] In a preferred embodiment of the present application, in step S1, the alcohol can be removed by distillation, i.e. the step of "removing alcohol" can include distillation to remove alcohol at 80-135°C. Here, 80-135°C refers to the temperature of the reaction system, and the alcohol can be removed at different temperatures by adjusting the distillation pressure. In order to improve the heat preservation performance of the obtained silica microspheres, it is preferred to distill and remove alcohol at 130-135°C. This is also an unexpected finding of the present application.

[0028] In a preferred embodiment of the present application, in order to further ensure the morphology of the obtained microspheres and ensure uniformity, in step S2, the mass ratio of the pre-polymer to water is (0.05-0.2):1.

[0029] In a preferred embodiment of the present application, in step S2, the emulsification temperature is 5-50°C, and in order to improve the heat preservation performance of the obtained silica microspheres, the emulsification temperature is preferably 5-35°C. This is also one of the core improvements of the present application. The emulsification time is preferably 0.5-1h.

[0030] In a specific embodiment of the present application, in step S2, the pre-polymer obtained in step S1 can be added dropwise into water to mix the two. Preferably, the pre-polymer is added dropwise for 0.5-1h, and the dropwise addition temperature is 5-50°C, preferably 5-35°C. In a preferred embodiment of the present application, the dropwise addition temperature and the emulsification temperature are the same.

[0031] In a preferred embodiment of the present application, in step S2, the pH of the system is adjusted to 7.5-8.5 after emulsification. The applicant has found that if the pH of the system is too low, the strength of the synthetic microspheres will be poor, and if the pH of the system is too high, the particle size of the synthetic microspheres will be more uneven, and the porosity will be lower. In this step, the pH of the system can be adjusted to alkaline using a material commonly used in the art, such as an aqueous ammonia solution, etc. In a specific embodiment of the present application, after the pH is adjusted to alkaline, the subsequent step is performed after stirring for 0.5-1 h.

[0032] In a specific embodiment of the present application, "aging" is an aging step commonly used in the art, such as static aging, etc. The aging time is a common aging time in the art, and the effect of aging is achieved, such as 2 h, etc., which is not particularly limited in the present application. In the present application, the solid can be obtained by using a commonly used method such as centrifugation or filtration. The "drying" also uses a drying method commonly used in the art, which is not particularly limited in the present application.

[0033] Another object of the present application is to provide modified hollow porous silica microspheres obtained by the above preparation method.

[0034] Still another object of the present application is to provide the use of the above preparation method and the above modified hollow porous silica microspheres obtained by the above preparation method in coatings. In particular, the use in thermal insulation coatings.

[0035] The present application uses low economic value 1,2-bis(trialkoxysilyl)ethane as one of the main silicon sources, which is a by-product of the synthesis of vinyltrialkoxysilane. The different silanes are first separately pre-hydrolyzed and then mixed and condensed, which avoids the high hydrolysis and polymerization of the easily hydrolyzed and polymerized silanes and the non-hydrolysis and polymerization of the silanes that are not easily hydrolyzed and polymerized, thereby preventing the preparation of prepolymers and the modification from failing. The preparation process is simple, the raw material cost is low, the morphology of the obtained microspheres is complete and there is no a large amount of debris, the porous microsphere yield can be slightly improved (the higher the yield, the higher the production efficiency), the operating conditions are mild, and the process is easy to industrialize. The silica microspheres obtained by the present application are hollow and porous, and the size is in the micron level. The modified hollow porous silica microspheres obtained by the present application are complete in shape, have few debris, high porosity and structural strength, good dispersibility, no adhesion and agglomeration, and no obvious breakage and collapse after drying. The spherical shape is complete, the microspheres are highly dispersed in the coating (the microspheres obtained by the present application are good in dispersibility, have no adhesion and agglomeration, and are still dispersed after drying), and the thermal insulation performance of the coating can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The scanning electron microscope photograph of the silica microspheres obtained in Example 3 is shown at 500 times magnification;

[0037] Figure 2 Scanning electron micrograph of the silica microspheres obtained in Example 4, magnification 600 times;

[0038] Figure 3 Scanning electron micrograph of the silica microspheres obtained in Example 8, magnification 500 times;

[0039] Figure 4 Scanning electron micrograph of the silica microspheres obtained in Example 8, magnification 1000 times;

[0040] Figure 5 Scanning electron micrograph of the silica microspheres obtained in Example 1, magnification 500 times;

[0041] Figure 6 Scanning electron micrograph of the silica microspheres obtained in Example 1, magnification 2000 times. DETAILED DESCRIPTION

[0042] The specific embodiments of the present application will be further described in conjunction with the following examples. The following examples are used to illustrate the present application but are not intended to limit the scope of the present application.

[0043] In the present application, "%" is mass percentage unless otherwise specified. In the present application, the weight parts can be μg, mg, g, kg and other weight units known in the art, and can also be multiples thereof, such as 1 / 10, 1 / 100, 10 times, 100 times, etc. In the present application, the amount of each substance is determined according to the above-mentioned proportions, and the total mass of the substances is not necessarily 100 parts by weight, but can be less than 100 parts by mass or greater than 100 parts by mass, as long as it is within the above-mentioned proportion.

[0044] In the present application, the yield of the porous microspheres is the mass ratio of the obtained dry microspheres to water (water for dispersing and emulsifying the prepolymer).

[0045] Example 1

[0046] This example provides a modified hollow porous silica microsphere, and the preparation method comprises the following steps:

[0047] Pre-hydrolysis solution a: 208.3 g of tetraethyl orthosilicate was mixed with 21 g of ethanol to obtain a silane and alcohol mixture, 19 g of water was added to the mixture, and HCl was added to adjust the pH to 2, and then 19 g of ethanol was added to obtain an alcohol and water mixture, and the alcohol and water mixture was added dropwise to the silane and alcohol mixture under stirring at 25°C, and after the dropwise addition was completed, the temperature was raised to the refluxing temperature of alcohol, and the reaction was carried out for 2 h, and then the temperature was lowered to obtain the pre-hydrolysis solution a.

[0048] Pre-hydrolysis solution b: 206.4 g of propyl triethoxysilane was mixed with 21 g of ethanol to obtain a mixture of silane and alcohol, and then 13.5 g of water was added to the mixture, and HCl was added to adjust the pH to 2, and then 13.5 g of ethanol was mixed with the mixture of silane and alcohol to obtain an alcohol-water mixture, and the alcohol-water mixture was added dropwise to the mixture of silane and alcohol under stirring at 25°C, and then the temperature was raised to the refluxing temperature of alcohol, and the reaction was carried out for 3 h, and then the temperature was lowered to obtain the pre-hydrolysis solution.

[0049] Pre-hydrolysis solution c: 354.6 g of 1,2-bis(triethoxysilyl)ethane was mixed with 36 g of ethanol to obtain a mixture of silane and alcohol, and then 27 g of water was added to the mixture, and HCl was added to adjust the pH to 3, and then 27 g of ethanol was mixed with the mixture of silane and alcohol to obtain an alcohol-water mixture, and the alcohol-water mixture was added dropwise to the mixture of silane and alcohol under stirring at 25°C, and then the temperature was raised to the refluxing temperature of alcohol, and the reaction was carried out for 2 h, and then the temperature was lowered to obtain the pre-hydrolysis solution.

[0050] The pre-hydrolysis solution a 93.5 g, the pre-hydrolysis solution b 19.0 g, the pre-hydrolysis solution c 66.7 g, and PPG400 1.8 g were mixed to obtain a mixture, and the mixture was stirred and heated to the refluxing temperature of ethanol, and the refluxing reaction was carried out for 3 h, and then the ethanol was distilled out under normal pressure, and the temperature of the remaining materials in the system was 130°C, and then the temperature was lowered to obtain the prepolymer.

[0051] The pre-hydrolysis solution a 93.5 g, the pre-hydrolysis solution b 19.0 g, the pre-hydrolysis solution c 66.7 g, and PPG400 1.8 g were mixed to obtain a mixture, and the mixture was stirred and heated to the refluxing temperature of ethanol, and the refluxing reaction was carried out for 3 h, and then the ethanol was distilled out under normal pressure, and the temperature of the remaining materials in the system was 130°C, and then the temperature was lowered to obtain the prepolymer. Figure 5 and Figure 6 The scanning electron microscope photograph of the silica microspheres obtained in Example 1 shows that the microspheres are dispersed, and there is no agglomeration or adhesion, and the external surface is smooth and round, and the internal cavity is hollow.

[0052] The yield of the microspheres obtained in this example is 7.15%.

[0053] Example 2

[0054] The modified hollow porous silica microspheres provided in this example are prepared by the following steps:

[0055] The preparation methods of the pre-hydrolysis solution a, the pre-hydrolysis solution b, and the pre-hydrolysis solution c are the same as those in Example 1.

[0056] The pre-hydrolysis solution a 93.5 g, the pre-hydrolysis solution b 19.0 g, the pre-hydrolysis solution c 66.7 g, and PPG400 1.8 g were mixed to obtain a mixture, and the mixture was stirred and heated to the refluxing temperature of ethanol, and the refluxing reaction was carried out for 3 h, and then the ethanol was distilled out under normal pressure, and the temperature of the remaining materials in the system was 130°C, and then the temperature was lowered to obtain the prepolymer.

[0057] Take 30 g of prepolymer, drop into 200 g of pure water under stirring at 25 °C, the drop time is 0.5 h, after the drop is completed, emulsify under stirring at 25 °C for 0.5 h, add ammonia solution to adjust the pH to 8, stir for 0.5 h, then stand for aging for 2 h, filter and dry to obtain 14.36 g of modified hollow porous silica microspheres.

[0058] The yield of the microspheres obtained in this example is 7.18%.

[0059] Example 3

[0060] This example provides a modified hollow porous silica microsphere, and the preparation method comprises the following steps:

[0061] The preparation methods of the pre-hydrolysis solution a, the pre-hydrolysis solution b and the pre-hydrolysis solution c are the same as those in Example 1.

[0062] Take 30 g of prepolymer, drop into 200 g of pure water under stirring at 25 °C, the drop time is 0.5 h, after the drop is completed, emulsify under stirring at 25 °C for 0.5 h, add ammonia solution to adjust the pH to 8, stir for 0.5 h, then stand for aging for 2 h, filter and dry to obtain 14.36 g of modified hollow porous silica microspheres.

[0063] Take 30 g of prepolymer, drop into 200 g of pure water under stirring at 25 °C, the drop time is 0.5 h, after the drop is completed, emulsify under stirring at 25 °C for 0.5 h, add ammonia solution to adjust the pH to 8, stir for 0.5 h, then stand for aging for 2 h, filter and dry to obtain 14.36 g of modified hollow porous silica microspheres. Figure 1 The scanning electron microscope photograph of the silica microspheres obtained in this example shows that the microspheres are dispersed, without agglomeration and adhesion, and are smooth and round outside, and are porous. Figure 1

[0064] The yield of the microspheres obtained in this example is 7.13%.

[0065] Example 4

[0066] This example provides a modified hollow porous silica microsphere, and the preparation method comprises the following steps:

[0067] The preparation methods of the pre-hydrolysis solution a, the pre-hydrolysis solution b and the pre-hydrolysis solution c are the same as those in Example 1.

[0068] Take 30 g of prepolymer, drop into 200 g of pure water under stirring at 25 °C, the drop time is 0.5 h, after the drop is completed, emulsify under stirring at 25 °C for 0.5 h, add ammonia solution to adjust the pH to 8, stir for 0.5 h, then stand for aging for 2 h, filter and dry to obtain 14.36 g of modified hollow porous silica microspheres. ​

[0069] Take 30 g of the prepolymer and add it dropwise to 200 g of pure water under stirring at 25 °C, the dropwise addition time being 0.5 h, after the dropwise addition is completed, emulsify under stirring at 25 °C for 0.5 h, add an ammonia water solution to adjust the pH to 8, stir for 0.5 h, then stand for aging for 2 h, after filtration and drying, 13.9 g of the modified hollow porous silica microspheres are obtained. Figure 2 The scanning electron microscope photograph of the silica microspheres obtained in this example shows that the microspheres are dispersed, without agglomeration or adhesion, and have a round shape and a porous interior. Figure 2 The scanning electron microscope photograph of the silica microspheres obtained in this example shows that the microspheres are dispersed, without agglomeration or adhesion, and have a round shape and a porous interior.

[0070] The yield of the microspheres obtained in this example is 6.95%.

[0071] Example 5

[0072] This example provides a modified hollow porous silica microsphere, and the preparation method comprises the following steps:

[0073] The preparation methods of the pre-hydrolysis liquid a, the pre-hydrolysis liquid b and the pre-hydrolysis liquid c are the same as in Example 1.

[0074] Take 30 g of the prepolymer and add it dropwise to 200 g of pure water under stirring at 25 °C, the dropwise addition time being 0.5 h, after the dropwise addition is completed, emulsify under stirring at 25 °C for 0.5 h, add an ammonia water solution to adjust the pH to 8, stir for 0.5 h, then stand for aging for 2 h, after filtration and drying, 13.9 g of the modified hollow porous silica microspheres are obtained.

[0075] Take 30 g of the prepolymer and add it dropwise to 200 g of pure water under stirring at 25 °C, the dropwise addition time being 0.5 h, after the dropwise addition is completed, emulsify under stirring at 25 °C for 0.5 h, add an ammonia water solution to adjust the pH to 8, stir for 0.5 h, then stand for aging for 2 h, after filtration and drying, 13.9 g of the modified hollow porous silica microspheres are obtained.

[0076] The yield of the microspheres obtained in this example is 7.32%.

[0077] Example 6

[0078] This example provides a modified hollow porous silica microsphere, and the preparation method comprises the following steps:

[0079] The preparation methods of the pre-hydrolysis liquid a, the pre-hydrolysis liquid b and the pre-hydrolysis liquid c are the same as in Example 1.

[0080] Take 30 g of the prepolymer and add it dropwise to 200 g of pure water under stirring at 25 °C, the dropwise addition time being 0.5 h, after the dropwise addition is completed, emulsify under stirring at 25 °C for 0.5 h, add an ammonia water solution to adjust the pH to 8, stir for 0.5 h, then stand for aging for 2 h, after filtration and drying, 13.9 g of the modified hollow porous silica microspheres are obtained.

[0081] Take 30 g of the prepolymer, add it dropwise to 200 g of pure water under stirring at 25 °C, the dropwise addition time is 0.5 h, after the dropwise addition, stir the emulsion at 25 °C for another 0.5 h, add an ammonia solution to adjust the pH to 8, stir for 0.5 h, then stand for aging for 2 h, filter and dry to obtain 14.04 g of the modified hollow porous silica microspheres.

[0082] The yield of the microspheres obtained in this example is 7.02%.

[0083] Example 7

[0084] This example provides a modified hollow porous silica microsphere, and the preparation method comprises the following steps:

[0085] The preparation methods of the pre-hydrolysis solution a, the pre-hydrolysis solution b and the pre-hydrolysis solution c are the same as those in Example 1.

[0086] Take 30 g of the prepolymer, add it dropwise to 200 g of pure water under stirring at 25 °C, the dropwise addition time is 0.5 h, after the dropwise addition, stir the emulsion at 25 °C for another 0.5 h, add an ammonia solution to adjust the pH to 8, stir for 0.5 h, then stand for aging for 2 h, filter and dry to obtain 14.04 g of the modified hollow porous silica microspheres.

[0087] Take 30 g of the prepolymer, add it dropwise to 200 g of pure water under stirring at 25 °C, the dropwise addition time is 0.5 h, after the dropwise addition, stir the emulsion at 25 °C for another 0.5 h, add an ammonia solution to adjust the pH to 8, stir for 0.5 h, then stand for aging for 2 h, filter and dry to obtain 14.04 g of the modified hollow porous silica microspheres.

[0088] The yield of the microspheres obtained in this example is 7.29%.

[0089] Example 8

[0090] This example provides a modified hollow porous silica microsphere, and the preparation method comprises the following steps:

[0091] The preparation methods of the pre-hydrolysis solution a, the pre-hydrolysis solution b and the pre-hydrolysis solution c are the same as those in Example 1.

[0092] Take 30 g of the prepolymer, add it dropwise to 200 g of pure water under stirring at 25 °C, the dropwise addition time is 0.5 h, after the dropwise addition, stir the emulsion at 25 °C for another 0.5 h, add an ammonia solution to adjust the pH to 8, stir for 0.5 h, then stand for aging for 2 h, filter and dry to obtain 14.04 g of the modified hollow porous silica microspheres.

[0093] Take 30 g of prepolymer, drop into 200 g of pure water under stirring at 25 °C, drop time is 0.5 h, after drop completion, stir emulsification at 25 °C for 0.5 h, add ammonia solution to adjust pH to 8, stir for 0.5 h, then stand for aging for 2 h, after filtration and drying, 14.28 g of modified hollow porous silica microspheres are obtained. Figure 3 and Figure 4 The scanning electron microscope photograph of the silica microspheres obtained in this example is shown in the figure, from which it can be seen that the microspheres are dispersed, without agglomeration and adhesion, with a round outer surface and a porous inner surface.

[0094] The yield of the microspheres obtained in this example is 7.14%.

[0095] Example 9

[0096] This example provides a modified hollow porous silica microsphere, and the preparation method comprises the following steps:

[0097] The preparation methods of the pre-hydrolysis liquid a, the pre-hydrolysis liquid b and the pre-hydrolysis liquid c are the same as those in Example 1.

[0098] Take 30 g of prepolymer, drop into 200 g of pure water under stirring at 25 °C, drop time is 0.5 h, after drop completion, stir emulsification at 25 °C for 0.5 h, add ammonia solution to adjust pH to 8, stir for 0.5 h, then stand for aging for 2 h, after filtration and drying, 14.28 g of modified hollow porous silica microspheres are obtained.

[0099] Take 30 g of prepolymer, drop into 200 g of pure water under stirring at 25 °C, drop time is 0.5 h, after drop completion, stir emulsification at 25 °C for 0.5 h, add ammonia solution to adjust pH to 8, stir for 0.5 h, then stand for aging for 2 h, after filtration and drying, 14.28 g of modified hollow porous silica microspheres are obtained.

[0100] The yield of the microspheres obtained in this example is 7.14%.

[0101] Comparative Example 1

[0102] This example provides a modified hollow porous silica microsphere, and the preparation method comprises the following steps:

[0103] Mix 72.9 g of tetraethyl orthosilicate, 15.5 g of propyl triethoxysilane, 53.2 g of 1,2-bis(triethoxysilyl)ethane, 1.8 g of PPG400 and 15 g of ethanol to obtain a mixture of silane and alcohol, add 12 g of ethanol to 11.7 g of water to which HCl has been added to adjust the pH to 2 to obtain an alcohol-water mixture, and drop the alcohol-water mixture into the mixture of silane and alcohol under stirring at 25°C, then raise the temperature to the refluxing temperature of ethanol, reflux for 3 h, then evaporate ethanol at normal pressure, and finally obtain a prepolymer with the remaining material in the system at 130°C.

[0104] Take 30 g of the prepolymer and drop it into 200 g of pure water under stirring at 25°C, the dropping time is 0.5 h, then stir the mixture at 25°C for 0.5 h after the dropping is completed, add an ammonia solution to adjust the pH of the system to 8, stir for 0.5 h, then let it stand for 2 h, and finally obtain 12.9 g of silica microspheres after filtration and drying.

[0105] The yield of the microspheres obtained in the comparative example is 6.45%.

[0106] Experimental Example

[0107] Mix 6 parts by weight of the silica microspheres prepared in the examples and comparative examples, 1.5 parts by weight of water and 14 parts by weight of a binder polyurethane resin to obtain a thermal insulation coating after low-speed stirring for 10 min, the mass ratio of the silica microspheres to the binder polyurethane resin (purchased from Cangzhou Datong Anticorrosion Thermal Insulation Material Co., Ltd. FG Cryogenic Adhesive) is 3:7. The solid content of the silica microspheres in the thermal insulation coating obtained is 28 wt%.

[0108] Use 196T nylon filament yarn with a fineness of 70D x 160D as a substrate, coat the above-mentioned thermal insulation coating on the surface of the substrate, and then dry the substrate with the thermal insulation coating to obtain a thermal insulation fabric. The drying temperature is 105°C, the time is 6 min, and the thickness of the thermal insulation coating coated on the surface of the substrate is 0.12 mm.

[0109] It is tested that the silica microspheres prepared in the examples and comparative examples are used to prepare a coating, and the coating is coated on the surface of a fabric substrate to obtain a thermal insulation fabric, the thermal conductivity coefficient of the thermal insulation fabric at room temperature (25°C) is shown in Table 1. The test method of the thermal conductivity coefficient is GB-T 10295-2008 Determination of Steady-state Thermal Resistance and Related Properties of Thermal Insulation Materials by Heat Flow Meter Method. The average size is detected by using a COXEM scanning electron microscope, the maximum particle size value (i.e. the upper limit) in the range is determined under a magnification of 100 times, and the minimum particle size value (the lower limit) is determined under a magnification of 2000 times.

[0110] Table 1 Performance Test Results

[0111]

[0112] As can be seen from Table 1, the modified hollow porous silica microspheres of the present application can be used as a heat insulation material, and the fabric has good heat insulation effect.

[0113] Finally, the method of the present application is only a preferred embodiment, and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for producing a modified hollow porous silica microsphere, characterized by, Comprising the following steps: S1, mixing a pre-hydrolysis solution of orthosilicate, a pre-hydrolysis solution of alkyl trialkoxysilane, a pre-hydrolysis solution of 1,2-bis(trialkoxysilyl)ethane and a polyol to obtain a mixture, refluxing and reacting, removing alcohol to obtain a prepolymer; S2, mixing the prepolymer obtained in step S1 with water, emulsifying, adjusting the pH of the system to alkaline, aging, taking the solid, and drying to obtain the product; The preparation method of the pre-hydrolysis solution of orthosilicate comprises the following steps: Mixing the orthosilicate with a first alcohol uniformly to obtain an orthosilicate alcohol mixture, dropping a mixture of water and a second alcohol into the orthosilicate alcohol mixture, reacting at the refluxing temperature of alcohol for 2-3 hours, and cooling to obtain the product; using an acidity regulator to adjust the pH of the water to 2-3; the first alcohol and the second alcohol are saturated alcohols corresponding to siloxy functional groups in the orthosilicate; The preparation method of the pre-hydrolysis solution of alkyl trialkoxysilane comprises the following steps: Mixing the alkyl trialkoxysilane with a first alcohol uniformly to obtain an alkyl trialkoxysilane alcohol mixture, dropping a mixture of water and a second alcohol into the alkyl trialkoxysilane alcohol mixture, reacting at the refluxing temperature of alcohol for 2-3 hours, and cooling to obtain the product; using an acidity regulator to adjust the pH of the water to 2-3; the first alcohol and the second alcohol are saturated alcohols corresponding to siloxy functional groups in the alkyl trialkoxysilane; The preparation method of the pre-hydrolysis solution of 1,2-bis(trialkoxysilyl)ethane comprises the following steps: Mixing the 1,2-bis(trialkoxysilyl)ethane with a first alcohol uniformly to obtain a 1,2-bis(trialkoxysilyl)ethane alcohol mixture, dropping a mixture of water and a second alcohol into the 1,2-bis(trialkoxysilyl)ethane alcohol mixture, reacting at the refluxing temperature of alcohol for 2-3 hours, and cooling to obtain the product; using an acidity regulator to adjust the pH of the water to 2-3; the first alcohol and the second alcohol are saturated alcohols corresponding to siloxy functional groups in the 1,2-bis(trialkoxysilyl)ethane; In step S1, the polyol is PPG with a molecular weight of 200-1000.

2. The production method according to claim 1, characterized by, The orthosilicate is one or more of methyl orthosilicate, ethyl orthosilicate, and butyl orthosilicate; And / or, the alkyl trialkoxysilane is methyl trialkoxysilane, propyl trialkoxysilane, hexyl trialkoxysilane, or octyl trialkoxysilane; And / or, the 1,2-bis(trialkoxysilyl)ethane is 1,2-bis(trimethoxysilyl)ethane or 1,2-bis(triethoxysilyl)ethane.

3. The preparation method according to claim 2, characterized in that, The orthosilicate is ethyl orthosilicate; And / or, the alkyl trialkoxysilane is propyl triethoxysilane; And / or, the 1,2-bis(trialkoxysilyl)ethane is 1,2-bis(triethoxysilyl)ethane.

4. The production method according to claim 3, characterized by, The orthosilicate is ethyl orthosilicate, the alkyl trialkoxysilane is propyl triethoxysilane, and the 1,2-bis(trialkoxysilyl)ethane is 1,2-bis(triethoxysilyl)ethane.

5. The production method according to any one of claims 1 to 4, characterized by, The molar ratio of silicon in the orthosilicate pre-hydrolysate, silicon in the alkyltrialkoxysilane pre-hydrolysate, and silicon in the 1,2-bis(trialkoxysilyl)ethane pre-hydrolysate in step S1 is 1:(0.02-0.6):(0.1-3).

6. The production method according to claim 5, wherein The molar ratio of silicon in the orthosilicate pre-hydrolysate, silicon in the alkyltrialkoxysilane pre-hydrolysate, and silicon in the 1,2-bis(trialkoxysilyl)ethane pre-hydrolysate in step S1 is 1:(0.1-0.3):(0.4-1.3).

7. The production method according to any one of claims 1 to 4, characterized by, The polyol in step S1 is PPG with a molecular weight of 400.

8. The production method according to any one of claims 1 to 4, characterized by, The amount of the polyol in step S1 is 0.5%~2% of the total weight of the orthosilicate pre-hydrolysate, alkyltrialkoxysilane pre-hydrolysate, and 1,2-bis(trialkoxysilyl)ethane pre-hydrolysate.

9. The production method according to any one of claims 1 to 4, characterized by, The step of "removing alcohol" in step S1 includes distilling alcohol away at 80~135℃.

10. The method of claim 9, wherein, The step of "removing alcohol" in step S1 includes distilling alcohol away at 130~135℃.

11. The production method according to any one of claims 1 to 4, characterized by, The temperature for emulsification in step S2 is 5℃~50℃.

12. The method of claim 11, wherein, The temperature for emulsification in step S2 is 5℃~35℃.

13. The modified hollow porous silica microspheres obtained by the preparation method in any one of claims 1 to 12.

14. The use of the modified hollow porous silica microspheres in claim 13 in paints.

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