Mesoporous silica microspheres and their application in thermal insulation materials

Abstract

The present invention relates to the field of mesoporous silica technology, specifically a kind of mesoporous silica microspheres and their application in thermal insulation materials. The invention uses polyoxypropylene glycol and isophorone diisocyanate as raw materials, reacts to generate a polyurethane prepolymer, and uses hydroxyethyl methacrylate to cap the end to generate a double-bond-terminated polyurethane prepolymer, and then initiates the grafting of acrylate monomers and KH-570 by an initiator to generate a polyurethane-modified acrylate emulsion, and uses the polyurethane-modified acrylate emulsion as the main ingredient of the thermal insulation coating, adds the large-pore mesoporous silica or titanium dioxide-loaded mesoporous silica mentioned in the above scheme, and cooperates with components such as a dispersant and a defoamer to prepare a thermal insulation coating with excellent thermal insulation performance.

Description

Technical Field

[0001] The present invention relates to the technical field of mesoporous silica, in particular to mesoporous silica microspheres and applications thereof in thermal insulation materials. Background Art

[0002] Mesoporous materials are porous materials with pore sizes ranging from 2 to 50 nm. Their morphologies include two-dimensional hexagonal, cubic, lamellar, cylindrical, spherical, worm-like, and honeycomb structures. Mesoporous silica is the most widely used mesoporous material and is a product of particular interest to those skilled in the art.

[0003] In the preparation of existing mesoporous silica, hexadecyltrimethylammonium bromide is generally used as a template. The average pore size of the prepared product is small, and its application in the field of thermal insulation materials is limited. Therefore, based on this situation, the present application discloses a mesoporous silica microsphere and its application in thermal insulation materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a mesoporous silica microsphere and its application in thermal insulation materials to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for preparing mesoporous silica microspheres comprises the following steps:

[0007] (1) mixing sodium metasilicate nonahydrate and deionized water, and stirring until dissolved to obtain a sodium metasilicate solution;

[0008] Mix polyamidoamine and hexadecyltrimethylammonium bromide, add deionized water, and stir evenly at 30-35° C. to obtain a template solution;

[0009] (2) Sodium metasilicate solution was added to the template solution, and the pH value was adjusted to 5-6 with 15% sulfuric acid by mass. The mixture was reacted at 80-85°C for 2-3 hours, aged at 25-30°C for 24 hours, filtered, washed and dried, and then transferred to 550-560°C for calcination for 5-6 hours at a heating rate of 1-1.5°C / min to remove the template and obtain mesoporous silica microspheres.

[0010] In this embodiment, in step (1), the molecular weight of the polyamide-amine is 200 to 1000 g / mol; and the amount of cetyltrimethylammonium bromide used is 15 wt% to 25 wt% of the polyamide-amine.

[0011] In this embodiment, in step (1), the concentration of the sodium metasilicate solution is 0.6-0.7 g / mL; the total amount of the template is 0.2 wt%-0.3 wt% of sodium metasilicate nonahydrate; and the concentration of the template solution is 2-3 g / L.

[0012] In this embodiment, the preparation steps of polyamide-amine are:

[0013] Ethylenediamine and methanol were mixed and stirred evenly under nitrogen atmosphere, methyl acrylate was added, and the mixture was stirred and reacted at 20-25°C for 24 hours. After the reaction, the solvent and impurities were removed by rotary evaporation under reduced pressure at 50°C to obtain a semi-substituted polyamide-amine;

[0014] The half-generation polyamide-amine is mixed with methanol, ethylenediamine is added under nitrogen environment, and the mixture is stirred and reacted at 20-25°C for 24 hours. After the reaction, the solvent and impurities are removed by vacuum rotary evaporation at 60°C to obtain the full-generation polyamide-amine.

[0015] The above-mentioned preparation method can be used to prepare a whole generation of polyamide-amine, and the process steps can be continued to react to generate multiple generations of hyperbranched polymers such as the second generation and the third generation. However, when the molecular weight of the polyamide-amine is higher, the average pore size of the mesoporous silica will decrease. The present application mainly aims to prepare mesoporous silica with a large pore size. Therefore, this scheme focuses on defining the technical feature: "The molecular weight of the polyamide-amine is 200 to 1000 g / mol". The molecular weight of the polyamide-amine is regulated by controlling the amount of reactants in the specific implementation method to obtain a polyamide-amine with a lower molecular weight.

[0016] Next, the scheme uses a compound of low molecular weight polyamide-amine and hexadecyltrimethylammonium bromide as a template, and sodium metasilicate as a silicon source to produce large-pore mesoporous silica with an average pore size of 6 to 10 nm. The pores of the mesoporous silica microspheres can hinder air circulation and are an excellent thermal insulation filler that can be widely used in the preparation of various materials such as thermal insulation coatings and thermal insulation felts. This application mainly aims to develop its application in thermal insulation coatings, so the scheme limits the components of the template and the molecular weight of polyamide-amine to produce large-pore mesoporous silica. When it is applied to thermal insulation coatings, the main resin in the coating can "interpenetrate" with the mesoporous silica, and the hardness, water resistance and thermal insulation properties of the coating can be improved.

[0017] In this embodiment, titanium dioxide is loaded on the surface of mesoporous silica microspheres, and the specific steps are as follows:

[0018] Mix mesoporous silica microspheres and deionized water, stir evenly, add sodium dodecylbenzenesulfonate, add titanium sulfate solution at 35-45°C, adjust the pH of the system to 2-3 with ammonia water, keep the reaction warm for 5-6 hours, let it stand for 24 hours, collect the product, wash and dry it, and then transfer it to 600-650°C for calcination for 3-4 hours to obtain mesoporous silica microspheres loaded with titanium dioxide.

[0019] In this embodiment, the amount of sodium dodecylbenzenesulfonate is 10 wt% to 12 wt% of the mesoporous silica microspheres; the concentration of the titanium sulfate solution is 0.1 mol / L, and the ratio of the mesoporous silica microspheres to the titanium sulfate solution is 1 g:80 mL.

[0020] In this embodiment, mesoporous silica microspheres are prepared according to any one of the preparation methods described above.

[0021] To further ensure the performance of the mesoporous silica in the thermal insulation coating, this application loads titanium dioxide on the surface of the mesoporous silica and limits the reaction temperature to "35-45 ° C". At this time, the reaction temperature is low, and it is impossible to completely coat the surface of the mesoporous silica with titanium dioxide. The titanium dioxide deposition is uneven and the amount is small, so it will not affect the "large-aperture interpenetration" scheme. At the same time, the deposition of titanium dioxide can further improve the thermal insulation performance of the mesoporous silica. And due to the deposition of titanium dioxide on the surface, the surface hardness of the thermal insulation coating is also improved.

[0022] A method for preparing a thermal insulation coating comprises the following steps:

[0023] S1: Mix polyoxypropylene glycol, isophorone diisocyanate, and dibutyltin dilaurate after vacuum dehydration, react at 80-85°C for 1-2 hours, add dimethylolpropionic acid, continue to react for 2-3 hours, then add hydroxyethyl methacrylate to cap the mixture, adjust the viscosity with acetone, cool to 40-50°C, neutralize with triethylamine for 20-30 minutes to a neutralization rate of 90%, and disperse in deionized water for 20-30 minutes to obtain a double-bond-terminated polyurethane prepolymer.

[0024] S2: Take a double-bond terminated polyurethane prepolymer, add azobisisobutyronitrile at 60-65°C, raise the temperature to 80-85°C, add acrylate monomer and KH-570, and continue the reaction for 4-5 hours to obtain a polyurethane emulsion;

[0025] S3: Take the mesoporous silica microspheres described above, add deionized water and mix, then add dispersant, stir evenly, add hollow glass microspheres, stir for 30 to 40 minutes to obtain a filler dispersion; add the filler dispersion, defoamer, and leveling agent to the polyurethane emulsion, stir evenly to obtain a thermal insulation coating.

[0026] In this embodiment, in step S1, the amounts of the components of the double-bond terminated polyurethane prepolymer are as follows: 30-35 parts by mass of polyoxypropylene glycol, 10-14 parts by mass of isophorone diisocyanate, 3-3.5 parts by mass of dimethylolpropionic acid, 1.5-2.5 parts by mass of hydroxyethyl methacrylate, and 0.3-0.5 parts by mass of dibutyltin dilaurate; the solid content of the double-bond terminated polyurethane prepolymer is 30-40%.

[0027] In step S2, the amount of azobisisobutyronitrile is 0.5wt% to 1wt% of the acrylate monomer, and the mass ratio of the total mass of the acrylate monomer to the solid in the double-bond terminated polyurethane prepolymer is 1:(2-3); the amount of KH-570 is 5wt% to 6wt% of the acrylate monomer; the acrylate monomer includes butyl acrylate, methyl methacrylate and dodecafluoroheptyl methacrylate in a mass ratio of 3:4:1.

[0028] In this embodiment, in step S3, the amounts of the components of the thermal insulation coating are as follows: by mass fraction, 60-70% of polyurethane emulsion, 10-12% of mesoporous silica microspheres, 0.5-0.6% of defoaming agent, 0.3-0.5% of dispersant, 7-8% of hollow glass microspheres, 0.5-1% of leveling agent, and the balance is deionized water.

[0029] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention uses polyoxypropylene glycol and isophorone diisocyanate as raw materials to react to generate a polyurethane prepolymer, and uses hydroxyethyl methacrylate to cap the end to generate a double-bond-capped polyurethane prepolymer, and then uses an initiator to initiate the grafting of acrylate monomers and KH-570 to generate a polyurethane-modified acrylate emulsion, and uses the polyurethane-modified acrylate emulsion as the main ingredient of the thermal insulation coating, adds the large-pore mesoporous silica or titanium dioxide-loaded mesoporous silica mentioned in the above scheme, and combines with components such as a dispersant and a defoaming agent to produce a thermal insulation coating with excellent thermal insulation performance.

[0030] At the same time, in this scheme, the acrylate monomers include butyl acrylate, methyl methacrylate and dodecafluoroheptyl methacrylate, and KH-570 is added to cooperate with each other to achieve fluorine and silicon modification, and the water resistance of the prepared thermal insulation coating is improved; the scheme achieves thermal insulation through the combination of large-pore mesoporous silica or titanium dioxide-loaded mesoporous silica and hollow glass microspheres, and the overall performance of the coating is excellent. DETAILED DESCRIPTION

[0031] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0032] In the following examples, the preparation steps of polyamide-amine are as follows: 0.15 mol of ethylenediamine and 30 mL of methanol are mixed, stirred evenly under a nitrogen environment, 1.2 mol of methyl acrylate is added, and the mixture is stirred and reacted at 25°C for 24 hours. After the reaction, the solvent and impurities are removed by rotary evaporation under reduced pressure at 50°C to obtain a half-generation polyamide-amine; 0.05 mol of the half-generation polyamide-amine is mixed with 50 mL of methanol, 1.2 mol of ethylenediamine is added under a nitrogen environment, the mixture is stirred and reacted at 25°C for 24 hours, and the solvent and impurities are removed by rotary evaporation under reduced pressure at 60°C to obtain a polyamide-amine.

[0033] In the following examples, the molecular weight of polyoxypropylene glycol is 2000, provided by Jiangsu Zhongshan Chemical; the model of hollow glass microspheres is VS5500, provided by 3M Company; the model of dispersant is orotan731A, provided by Dow Chemical; the model of defoaming agent is PA-311, provided by Foshan Nanhai Datian Chemical Co., Ltd.; the model of leveling agent is BYK-332, provided by BYK Chemical (Shanghai) Co., Ltd.

[0034] Example 1: A method for preparing mesoporous silica microspheres, comprising the following steps:

[0035] (1) 20 g of sodium metasilicate nonahydrate and deionized water were mixed and stirred until dissolved to obtain a sodium metasilicate solution; the concentration of the sodium metasilicate solution was 0.6 g / mL.

[0036] Polyamide-amine and hexadecyltrimethylammonium bromide are mixed, deionized water is added, and the mixture is stirred uniformly at 30° C. to obtain a template solution; the amount of the hexadecyltrimethylammonium bromide is 15wt% of the polyamide-amine, the total amount of the template is 0.2wt% of sodium metasilicate nonahydrate, and the concentration of the template solution is 3g / L.

[0037] (2) Sodium metasilicate solution was added to the template solution, and the pH value was adjusted to 6 with 15% sulfuric acid by mass. The mixture was reacted at 80°C for 3 h, aged at 25°C for 24 h, filtered, washed and dried, and then transferred to 550°C for calcination at a heating rate of 1°C / min for 6 h to remove the template and obtain mesoporous silica microspheres.

[0038] Example 2: A method for preparing mesoporous silica microspheres, comprising the following steps:

[0039] (1) 20 g of sodium metasilicate nonahydrate and deionized water were mixed and stirred until dissolved to obtain a sodium metasilicate solution; the concentration of the sodium metasilicate solution was 0.6 g / mL.

[0040] Polyamide-amine and hexadecyltrimethylammonium bromide are mixed, deionized water is added, and the mixture is stirred uniformly at 35° C. to obtain a template solution; the amount of the hexadecyltrimethylammonium bromide is 20wt% of the polyamide-amine, the total amount of the template is 0.25wt% of sodium metasilicate nonahydrate, and the concentration of the template solution is 3g / L.

[0041] (2) Sodium metasilicate solution was added to the template solution, and the pH value was adjusted to 6 with 15% sulfuric acid by mass. The mixture was reacted at 85°C for 3 h, aged at 25°C for 24 h, filtered, washed and dried, and then transferred to 550°C for calcination at a heating rate of 1°C / min for 6 h to remove the template and obtain mesoporous silica microspheres.

[0042] Example 3: A method for preparing mesoporous silica microspheres, comprising the following steps:

[0043] (1) 20 g of sodium metasilicate nonahydrate and deionized water were mixed and stirred until dissolved to obtain a sodium metasilicate solution; the concentration of the sodium metasilicate solution was 0.6 g / mL.

[0044] Polyamide-amine and hexadecyltrimethylammonium bromide are mixed, deionized water is added, and the mixture is stirred uniformly at 35° C. to obtain a template solution; the amount of the hexadecyltrimethylammonium bromide is 15wt% of the polyamide-amine, the total amount of the template is 0.25wt% of sodium metasilicate nonahydrate, and the concentration of the template solution is 3g / L.

[0045] (2) Sodium metasilicate solution was added to the template solution, and the pH value was adjusted to 6 with 15% sulfuric acid by mass. The mixture was reacted at 85°C for 2.5 hours, aged at 30°C for 24 hours, filtered, washed and dried, and then transferred to 550°C for calcination for 6 hours at a heating rate of 1°C / min to remove the template and obtain mesoporous silica microspheres.

[0046] Comparative Example 1: In Comparative Example 1, the template was adjusted based on Example 2.

[0047] A method for preparing mesoporous silica microspheres comprises the following steps:

[0048] (1) 20 g of sodium metasilicate nonahydrate and deionized water were mixed and stirred until dissolved to obtain a sodium metasilicate solution; the concentration of the sodium metasilicate solution was 0.6 g / mL.

[0049] Hexadecyltrimethylammonium bromide was mixed, deionized water was added, and the mixture was stirred at 35° C. to obtain a template solution; the total amount of the template was 0.25 wt % of the sodium metasilicate nonahydrate, and the concentration of the template solution was 3 g / L.

[0050] (2) Sodium metasilicate solution was added to the template solution, and the pH value was adjusted to 6 with 15% sulfuric acid by mass. The mixture was reacted at 85°C for 3 h, aged at 25°C for 24 h, filtered, washed and dried, and then transferred to 550°C for calcination at a heating rate of 1°C / min for 6 h to remove the template and obtain mesoporous silica microspheres.

[0051] Test Experiment 1: The mesoporous silica microspheres prepared in Examples 1 to 3 and Comparative Example 1 were tested for their BET specific surface area and average pore size. The specific test data are shown in Table 1 below:

[0052] Table 1

[0053] project Example 1 Example 2 Example 3 Comparative Example 1 <![CDATA[BET specific surface area m 2 / g]]> 347.4 389.2 407.3 513.6 Average pore size / nm 10.7 8.6 7.8 4.7

[0054] Example 4:

[0055] The mesoporous silica microspheres prepared in Example 2 were loaded with titanium dioxide on their surfaces. The specific steps were as follows: 2 g of mesoporous silica microspheres were mixed with 100 mL of deionized water, stirred evenly, 0.2 g of sodium dodecylbenzenesulfonate was added, 160 mL of titanium sulfate solution was added at 35°C, the pH of the system was adjusted to 3 with ammonia water, the reaction was kept warm for 5 hours, the mixture was allowed to stand for 24 hours, the product was collected, washed and dried, and then transferred to 600°C for calcination for 4 hours to obtain mesoporous silica microspheres loaded with titanium dioxide. The concentration of the titanium sulfate solution was 0.1 mol / L.

[0056] Comparative Example 2: The reaction temperature was adjusted based on Example 4.

[0057] The mesoporous silica microspheres prepared in Example 2 were loaded with titanium dioxide on their surfaces. The specific steps were as follows: 2 g of mesoporous silica microspheres were mixed with 100 mL of deionized water, stirred evenly, 0.2 g of sodium dodecylbenzenesulfonate was added, 160 mL of titanium sulfate solution was added at 65°C, the pH of the system was adjusted to 3 with ammonia water, the reaction was kept warm for 5 hours, the mixture was allowed to stand for 24 hours, the product was collected, washed and dried, and then transferred to 600°C for calcination for 4 hours to obtain mesoporous silica microspheres loaded with titanium dioxide. The concentration of the titanium sulfate solution was 0.1 mol / L.

[0058] Example 5: A method for preparing a thermal insulation coating, comprising the following steps:

[0059] S1: Mix polyoxypropylene glycol, isophorone diisocyanate, and dibutyltin dilaurate after vacuum dehydration, react at 80°C for 2 hours, add dimethylolpropionic acid, continue to react for 2 hours, then add hydroxyethyl methacrylate to cap the mixture, adjust the viscosity with acetone, cool to 40°C, neutralize with triethylamine for 30 minutes to a neutralization rate of 90%, and disperse in deionized water for 30 minutes to obtain a double-bond-terminated polyurethane prepolymer; the double-bond-terminated polyurethane prepolymer has a solid content of 30%.

[0060] In step S1, the amounts of the components of the double-bond terminated polyurethane prepolymer are as follows: in parts by mass: 35 parts of polyoxypropylene glycol, 12 parts of isophorone diisocyanate, 3 parts of dimethylolpropionic acid, 2 parts of hydroxyethyl methacrylate, and 0.5 parts of dibutyltin dilaurate.

[0061] S2: Take a double-bond terminated polyurethane prepolymer, add azobisisobutyronitrile at 65°C, raise the temperature to 85°C, add acrylate monomer and KH-570, and continue the reaction for 5 hours to obtain a polyurethane emulsion;

[0062] In step S2, the mass ratio of the total mass of the acrylate monomer to the solids in the double-bond-terminated polyurethane prepolymer is 1:3; the acrylate monomer includes butyl acrylate, methyl methacrylate, and dodecafluoroheptyl methacrylate in a mass ratio of 3:4:1. The amount of azobisisobutyronitrile used is 0.8% by weight of the acrylate monomer, and the amount of KH-570 used is 6% by weight of the acrylate monomer.

[0063] S3: Add deionized water to the titanium dioxide-loaded mesoporous silica microspheres prepared in Example 4, mix, then add a dispersant, stir evenly, add hollow glass microspheres, stir for 30 minutes to obtain a filler dispersion; add the filler dispersion, defoaming agent, and leveling agent to the polyurethane emulsion, stir evenly to obtain a thermal insulation coating.

[0064] The dosage of each component of the thermal insulation coating is: by mass fraction, 65% polyurethane emulsion, 12% mesoporous silica microspheres loaded with titanium dioxide, 0.5% defoamer, 0.5% dispersant, 7% hollow glass microspheres, 0.5% leveling agent, and the balance is deionized water.

[0065] Example 6: A method for preparing a thermal insulation coating, comprising the following steps:

[0066] S1: Mix polyoxypropylene glycol, isophorone diisocyanate, and dibutyltin dilaurate after vacuum dehydration, react at 85°C for 2 hours, add dimethylolpropionic acid, continue to react for 2 hours, then add hydroxyethyl methacrylate to cap the mixture, adjust the viscosity with acetone, cool to 40°C, neutralize with triethylamine for 30 minutes to a neutralization rate of 90%, and disperse in deionized water for 30 minutes to obtain a double-bond-terminated polyurethane prepolymer; the double-bond-terminated polyurethane prepolymer has a solid content of 30%.

[0067] In step S1, the amounts of the components of the double-bond terminated polyurethane prepolymer are as follows: in parts by mass: 35 parts of polyoxypropylene glycol, 12 parts of isophorone diisocyanate, 3 parts of dimethylolpropionic acid, 2 parts of hydroxyethyl methacrylate, and 0.5 parts of dibutyltin dilaurate.

[0068] S2: Take a double-bond terminated polyurethane prepolymer, add azobisisobutyronitrile at 65°C, raise the temperature to 85°C, add acrylate monomer and KH-570, and continue the reaction for 4 hours to obtain a polyurethane emulsion;

[0069] In step S2, the mass ratio of the total mass of the acrylate monomer to the solids in the double-bond-terminated polyurethane prepolymer is 1:3; the acrylate monomer includes butyl acrylate, methyl methacrylate, and dodecafluoroheptyl methacrylate in a mass ratio of 3:4:1. The amount of azobisisobutyronitrile used is 0.8% by weight of the acrylate monomer, and the amount of KH-570 used is 6% by weight of the acrylate monomer.

[0070] S3: Add deionized water to the mesoporous silica microspheres prepared in Example 2, mix, then add a dispersant, stir evenly, add hollow glass microspheres, stir for 30 minutes to obtain a filler dispersion; add the filler dispersion, defoaming agent, and leveling agent to the polyurethane emulsion, stir evenly to obtain a thermal insulation coating.

[0071] The dosage of each component of the thermal insulation coating is: by mass fraction, 65% polyurethane emulsion, 12% mesoporous silica microspheres, 0.5% defoaming agent, 0.5% dispersant, 7% hollow glass microspheres, 0.5% leveling agent, and the balance is deionized water.

[0072] Example 7: A method for preparing a thermal insulation coating, comprising the following steps:

[0073] S1: Mix polyoxypropylene glycol, isophorone diisocyanate, and dibutyltin dilaurate after vacuum dehydration, react at 85°C for 1.5 hours, add dimethylolpropionic acid, continue to react for 2 hours, then add hydroxyethyl methacrylate to cap the mixture, adjust the viscosity with acetone, cool to 40°C, neutralize with triethylamine for 30 minutes to a neutralization rate of 90%, and disperse in deionized water for 30 minutes to obtain a double-bond-terminated polyurethane prepolymer; the double-bond-terminated polyurethane prepolymer has a solid content of 30%.

[0074] In step S1, the amounts of the components of the double-bond terminated polyurethane prepolymer are as follows: in parts by mass: 35 parts of polyoxypropylene glycol, 12 parts of isophorone diisocyanate, 3 parts of dimethylolpropionic acid, 2 parts of hydroxyethyl methacrylate, and 0.5 parts of dibutyltin dilaurate.

[0075] S2: Take a double-bond terminated polyurethane prepolymer, add azobisisobutyronitrile at 65°C, raise the temperature to 80°C, add acrylate monomer and KH-570, and continue the reaction for 4 hours to obtain a polyurethane emulsion;

[0076] In step S2, the mass ratio of the total mass of the acrylate monomer to the solids in the double-bond-terminated polyurethane prepolymer is 1:3; the acrylate monomer includes butyl acrylate, methyl methacrylate, and dodecafluoroheptyl methacrylate in a mass ratio of 3:4:1. The amount of azobisisobutyronitrile used is 0.8% by weight of the acrylate monomer, and the amount of KH-570 used is 6% by weight of the acrylate monomer.

[0077] S3: Add deionized water to the mesoporous silica microspheres prepared in Comparative Example 1, mix, then add a dispersant, stir evenly, add hollow glass microspheres, stir for 30 minutes to obtain a filler dispersion; add the filler dispersion, defoaming agent, and leveling agent to the polyurethane emulsion, stir evenly to obtain a thermal insulation coating.

[0078] The dosage of each component of the thermal insulation coating is: by mass fraction, 65% polyurethane emulsion, 12% mesoporous silica microspheres, 0.5% defoaming agent, 0.5% dispersant, 7% hollow glass microspheres, 0.5% leveling agent, and the balance is deionized water.

[0079] Comparative Example 3: In Comparative Example 3, the mesoporous silica microspheres were adjusted based on Example 5.

[0080] A method for preparing a thermal insulation coating comprises the following steps:

[0081] S1: Mix polyoxypropylene glycol, isophorone diisocyanate, and dibutyltin dilaurate after vacuum dehydration, react at 80°C for 2 hours, add dimethylolpropionic acid, continue to react for 2 hours, then add hydroxyethyl methacrylate to cap the mixture, adjust the viscosity with acetone, cool to 40°C, neutralize with triethylamine for 30 minutes to a neutralization rate of 90%, and disperse in deionized water for 30 minutes to obtain a double-bond-terminated polyurethane prepolymer; the double-bond-terminated polyurethane prepolymer has a solid content of 30%.

[0082] In step S1, the amounts of the components of the double-bond terminated polyurethane prepolymer are as follows: in parts by mass: 35 parts of polyoxypropylene glycol, 12 parts of isophorone diisocyanate, 3 parts of dimethylolpropionic acid, 2 parts of hydroxyethyl methacrylate, and 0.5 parts of dibutyltin dilaurate.

[0083] S2: Take a double-bond terminated polyurethane prepolymer, add azobisisobutyronitrile at 65°C, raise the temperature to 85°C, add acrylate monomer and KH-570, and continue the reaction for 5 hours to obtain a polyurethane emulsion;

[0084] In step S2, the mass ratio of the total mass of the acrylate monomer to the solids in the double-bond-terminated polyurethane prepolymer is 1:3; the acrylate monomer includes butyl acrylate, methyl methacrylate, and dodecafluoroheptyl methacrylate in a mass ratio of 3:4:1. The amount of azobisisobutyronitrile used is 0.8% by weight of the acrylate monomer, and the amount of KH-570 used is 6% by weight of the acrylate monomer.

[0085] S3: Add deionized water to the titanium dioxide-loaded mesoporous silica microspheres prepared in Comparative Example 2, mix, then add a dispersant, stir evenly, add hollow glass microspheres, stir for 30 minutes, and obtain a filler dispersion; add the filler dispersion, defoaming agent, and leveling agent to the polyurethane emulsion, stir evenly, and obtain a thermal insulation coating.

[0086] The dosage of each component of the thermal insulation coating is: by mass fraction, 65% polyurethane emulsion, 12% mesoporous silica microspheres loaded with titanium dioxide, 0.5% defoamer, 0.5% dispersant, 7% hollow glass microspheres, 0.5% leveling agent, and the balance is deionized water.

[0087] Detection experiment:

[0088] 1. The thermal insulation coatings prepared in Examples 5-7 and Comparative Example 3 were applied to tinplate sheets, allowed to stand for 3 days, and dried at 60°C. The surface hardness of the coatings was tested according to the method disclosed in GB / T6739, and the adhesion of the coatings was tested according to the cross-hatch method disclosed in GB / T9286. The coatings were then immersed in a 5% sodium hydroxide solution for 48 hours and observed for blistering, discoloration, or peeling.

[0089] 2. Take the thermal insulation coatings prepared in Examples 5 to 7 and Comparative Example 3, pour them into a polytetrafluoroethylene mold, dry them at 120°C to obtain a film, cut it into pieces of 2 cm × 2 cm in size, soak it in deionized water for 24 h, and test it at a temperature of 25°C. After taking it out, remove the surface moisture with absorbent paper, weigh it, and calculate the water absorption rate.

[0090] 3. Take the thermal insulation coating prepared in Examples 5 to 7 and Comparative Example 3, apply it to tinplate, let it stand for 3 days, and dry it at 60°C. The dry film thickness is 0.45 mm to prepare a sample plate; refer to the thermal insulation temperature difference test disclosed in HG / T4341, where the polystyrene foam box has a size of 420 mm × 330 mm × 330 mm and a wall thickness of 50 mm. The box is divided into two chambers by a 50 mm partition in the middle, and a 140 mm × 60 mm gap is provided on the top of the chamber for placing the sample plate; the sample not coated with the thermal insulation coating is used as a blank plate, and the back temperature of the sample plate and the blank plate is tested until the temperature remains constant within 5 minutes. The difference between the sample plate and the blank plate is the thermal insulation temperature difference.

[0091] The specific test data are shown in Table 2 below:

[0092] Table 2

[0093]

[0094] Conclusion: The invention uses polyoxypropylene glycol and isophorone diisocyanate as raw materials to react and generate a polyurethane prepolymer, and uses hydroxyethyl methacrylate to cap it to generate a double-bond-capped polyurethane prepolymer, and then uses an initiator to initiate the grafting of acrylate monomers and KH-570 to generate a polyurethane-modified acrylate emulsion, and uses the polyurethane-modified acrylate emulsion as the main material of the thermal insulation coating, adds the large-pore mesoporous silica or titanium dioxide-loaded mesoporous silica mentioned in the above scheme, and combines with dispersants, defoaming agents and other components to prepare a thermal insulation coating with excellent thermal insulation performance.

[0095] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing mesoporous silica microspheres, characterized in that: The following steps are involved: (1) mixing sodium metasilicate nonahydrate and deionized water, and stirring until dissolved to obtain a sodium metasilicate solution; Mix polyamidoamine and hexadecyltrimethylammonium bromide, add deionized water, and stir evenly at 30-35°C to obtain a template solution; (2) adding sodium metasilicate solution to the template solution, adjusting the pH to 5-6, reacting at 80-85°C for 2-3 hours, aging at 25-30°C for 24 hours, filtering, washing and drying, and then transferring to 550-560°C for calcination for 5-6 hours to obtain mesoporous silica microspheres; The preparation steps of polyamide-amine are as follows: ethylenediamine and methanol are mixed, stirred evenly under nitrogen atmosphere, methyl acrylate is added, and the mixture is stirred and reacted at 20-25°C for 24 hours. After the reaction, the solvent and impurities are removed by rotary evaporation under reduced pressure at 50°C to obtain a semi-generation polyamide-amine; The semi-generation polyamide-amine is mixed with methanol, ethylenediamine is added under nitrogen atmosphere, and the mixture is stirred at 20-25°C for 24 hours. After the reaction, the solvent and impurities are removed by rotary evaporation under reduced pressure at 60°C to obtain the polyamide-amine; The molecular weight of the polyamide-amine is 200-1000 g / mol; the amount of the hexadecyltrimethylammonium bromide is 15 wt%-25 wt% of the polyamide-amine; The surface of mesoporous silica microspheres is loaded with titanium dioxide. The specific steps are: mix the mesoporous silica microspheres and deionized water, stir evenly, add sodium dodecylbenzenesulfonate, add titanium sulfate solution at 35-45°C, adjust the pH of the system to 2-3 with ammonia water, keep the reaction warm for 5-6 hours, let it stand for 24 hours, collect the product, wash and dry it, and then transfer it to 600-650°C for calcination for 3-4 hours to obtain mesoporous silica microspheres loaded with titanium dioxide.

2. The method for preparing mesoporous silica microspheres according to claim 1, wherein: In step (1), the concentration of the sodium metasilicate solution is 0.6-0.7 g / mL; the total amount of the template is 0.2 wt%-0.3 wt% of sodium metasilicate nonahydrate; and the concentration of the template solution is 2-3 g / L.

3. The method for preparing mesoporous silica microspheres according to claim 1, wherein: The dosage of the sodium dodecylbenzenesulfonate is 10 wt% to 12 wt% of the mesoporous silica microspheres; and the concentration of the titanium sulfate solution is 0.1 mol / L.

4. Mesoporous silica microspheres prepared according to the preparation method according to any one of claims 1 to 3.

5. A method for preparing a thermal insulation coating, characterized in that: The following steps are involved: S1: Mix polyoxypropylene glycol, isophorone diisocyanate, and dibutyltin dilaurate after vacuum dehydration, react at 80-85°C for 1-2 hours, add dimethylolpropionic acid, continue to react for 2-3 hours, then add hydroxyethyl methacrylate to cap the mixture, adjust the viscosity with acetone, cool to 40-50°C, neutralize with triethylamine for 20-30 minutes, and disperse in deionized water for 20-30 minutes to obtain a double-bond-terminated polyurethane prepolymer; S2: Take a double-bond terminated polyurethane prepolymer, add azobisisobutyronitrile at 60-65°C, raise the temperature to 80-85°C, add acrylate monomer and KH-570, and continue the reaction for 4-5 hours to obtain a polyurethane emulsion; S3: Take the mesoporous silica microspheres described in claim 4, add deionized water and mix, then add a dispersant, stir evenly, add hollow glass microspheres, stir for 30 to 40 minutes to obtain a filler dispersion; add the filler dispersion, defoaming agent, and leveling agent to the polyurethane emulsion, stir evenly to obtain a thermal insulation coating.

6. The method for preparing a thermal insulation coating according to claim 5, characterized in that: In step S1, the amounts of the components of the double-bond terminated polyurethane prepolymer are as follows: 30-35 parts by mass of polyoxypropylene glycol, 10-14 parts by mass of isophorone diisocyanate, 3-3.5 parts by mass of dimethylolpropionic acid, 1.5-2.5 parts by mass of hydroxyethyl methacrylate, and 0.3-0.5 parts by mass of dibutyltin dilaurate; the solid content of the double-bond terminated polyurethane prepolymer is 30-40%. In step S2, the amount of azobisisobutyronitrile is 0.5wt%~1wt% of the acrylate monomer, and the mass ratio of the total mass of the acrylate monomer to the solid in the double-bond terminated polyurethane prepolymer is 1:(2~3); the amount of KH-570 is 5wt%~6wt% of the acrylate monomer; the acrylate monomer includes butyl acrylate, methyl methacrylate and dodecafluoroheptyl methacrylate in a mass ratio of 3:4:

1.

7. The method for preparing a thermal insulation coating according to claim 5, characterized in that: In step S3, the amounts of the components of the thermal insulation coating are as follows: by mass fraction, 60-70% of polyurethane emulsion, 10-12% of mesoporous silica microspheres, 0.5-0.6% of defoaming agent, 0.3-0.5% of dispersant, 7-8% of hollow glass microspheres, 0.5-1% of leveling agent, and the balance is deionized water.

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