A nano-ceramic microsphere thermal insulation material and its preparation method

Abstract

The present invention discloses a nano-ceramic microsphere thermal insulation material and a preparation method thereof, which relates to the field of thermal insulation materials and includes the following raw materials: silicone-acrylic emulsion, styrene-acrylic emulsion, modified nano-ceramic microspheres, silica aerogel, talc powder, dispersant, thickener, flame retardant and water. Among the flame retardants used in the present invention, sodium lignosulfonate, phosphate ester and amino group with reduced hydrophilicity cooperate to provide flame retardancy, endowing the thermal insulation material with strong waterproof and fireproof properties. The modified nano-ceramic microspheres used in the present invention, in combination with talc powder, endow the thermal insulation material with strong thermal insulation properties by using nano-ceramic microspheres with improved agglomeration. At the same time, a large conjugated system formed by the reaction of 6-(thiophen-2-yl)-1H-indazole and 2-methoxy-5-nitro-2,4,6-cycloheptatriene-1-one endows the thermal insulation material with strong anti-aging properties.

Description

Technical Field

[0001] The present invention relates to the field of thermal insulation materials, and particularly relates to a nano-ceramic microsphere thermal insulation material and a preparation method thereof. Background Art

[0002] Ceramic microspheres are hollow or solid spherical particles mainly composed of SiO2 and Al2O3, and their thermal conductivity is superior to that of vitrified microspheres and expanded perlite. After being compounded with a polymer matrix, ceramic microspheres can be used for heat insulation and protection of industrial furnaces, high-temperature pipelines, and the outer shells of spacecraft. Among them, high-performance ceramic microspheres (such as nano-scale ceramic microspheres) have more excellent heat insulation performance. However, nano-ceramic microspheres are prone to agglomeration in the polymer matrix and have poor dispersibility, which limits their use in nano-ceramic microsphere / polymer composite thermal insulation materials. When silicone-acrylic emulsion and styrene-acrylic emulsion are used as the polymer matrix, during the long-term use of the composite thermal insulation material, the polymer matrix will age under the influence of ultraviolet rays and other factors, which has an adverse effect on the use performance of the composite thermal insulation material.

[0003] To ensure that the composite thermal insulation material has strong fire resistance, a flame retardant also needs to be added thereto. Lignin, as a biomass material that is the second largest resource in nature after cellulose, exhibits excellent thermal stability and remarkable char-forming ability due to its unique aromatic structure and carbon content of up to 60%, and has broad application prospects. However, the abundant hydroxyl groups in lignin (such as sodium lignosulfonate) result in its high hydrophilicity, poor compatibility with silicone-acrylic emulsion, etc., and it also does not meet the use requirements of thermal insulation materials with high waterproof requirements, and its flame retardancy when used alone needs to be improved.

[0004] Based on this, a suitable modification method is urgently needed to improve the agglomeration of nano-ceramic microspheres and reduce the hydrophilicity of sodium lignosulfonate, so as to obtain a nano-ceramic microsphere / polymer composite thermal insulation material with strong heat insulation performance, aging resistance, fire resistance, waterproofness, etc. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a nano-ceramic microsphere thermal insulation material and a preparation method thereof.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A nano-ceramic microsphere thermal insulation material, comprising the following raw materials in parts by weight: 15-20 parts of silicone-acrylic emulsion, 15-20 parts of styrene-acrylic emulsion, 15-25 parts of modified nano-ceramic microspheres, 4-6 parts of silica aerogel, 10-15 parts of talcum powder, 1-2 parts of dispersant, 0.5-1 part of thickener, 5-10 parts of flame retardant, and 10-15 parts of water;

[0008] Further, the dispersant is KH560, and the thickener is hydroxyethyl cellulose;

[0009] The preparation of the nano-ceramic microsphere thermal insulation material comprises the following steps:

[0010] Stir the silicone-acrylic emulsion, styrene-acrylic emulsion, and water at a rotation speed of 600 - 800 rpm for 30 - 40 min. Then, successively add the modified nano-ceramic microspheres, silica aerogel, talcum powder, and dispersant, and stir at a rotation speed of 2000 - 3000 rpm for 1 - 1.5 h. Next, add the thickener and flame retardant, and stir at a rotation speed of 500 - 600 rpm for 30 - 40 min to obtain the nano-ceramic microsphere thermal insulation material;

[0011] The preparation of the flame retardant comprises the following steps:

[0012] Step A1: Mix sodium lignosulfonate and acid anhydride, and react under the action of a catalyst to obtain product 1a; oxidize product 1a with an oxidant solution to obtain product 2a;

[0013] Step A2: React the spirocyclic carboxylic acid-containing compound with product 2a under the action of 4-methylpyridine to obtain product 3a; mix and react product 3a and nitro-phosphoryl chloride-containing compound to obtain product 4a;

[0014] Step A3: Reduce product 4a with an iron powder and ammonium chloride reduction system to obtain the flame retardant;

[0015] The specific preparation steps of the flame retardant are as follows:

[0016] Step A1: Mix sodium lignosulfonate and acid anhydride, add a catalyst, and reflux and stir at 115 - 125 °C for 24 - 25 h to obtain a reaction solution. Then, add the reaction solution to an ice-cold ethanol solution to obtain a precipitate. Wash the precipitate until it is neutral, and then vacuum dry it at 45 - 50 °C for 8 - 8.5 h to obtain product 1a; add product 1a to ethanol, and then add an oxidant solution at 40 - 50 °C and stir and react for 5 - 5.5 h to obtain product 2a;

[0017] Further, the dosage ratio of sodium lignosulfonate, acid anhydride, and catalyst is 54 - 56 g : 28 - 30 g : 3 - 5 g; the dosage ratio of the reaction solution and the ice-cold ethanol solution is 88 - 92 g : 80 - 90 mL; the acid anhydride is linoleic anhydride, the ethanol solution is prepared by mixing ethanol and water in a volume ratio of 3 - 3.5 : 1, the catalyst is obtained by mixing 2-ethylimidazole and 1-methylimidazole in a mass ratio of 1 : 1.5; the dosage ratio of product 1a, ethanol, and oxidant solution is 84 - 86 g : 120 - 130 mL : 66 - 68 mL; the oxidant solution is obtained by mixing m-chloroperoxybenzoic acid and tetrahydrofuran in a dosage ratio of 19 - 21 g : 45 - 55 mL; the volume fraction of ethanol is 95%;

[0018] In the reaction process of Step A1, sodium lignosulfonate reacts with linoleic anhydride under the action of a catalyst to obtain esterified sodium lignosulfonate, that is, Product 1a containing sodium lignosulfonate and a long-chain alkane with a double bond in the linoleic acid group; the carbon-carbon double bond in Product 1a is oxidized to an epoxy group to obtain Product 2a containing sodium lignosulfonate and a long-chain alkane with an epoxy group in the linoleic acid group.

[0019] Step A2: In an inert gas atmosphere, a mixture of spirocyclic carboxylic acid and DMF is heated to 50-60 °C, 4-methylpyridine and Product 2a are added, and the mixture is stirred and reacted for 8-8.5 h to obtain Product 3a; Product 3a, nitro-phosphoryl chloride and ethyl acetate are mixed and refluxed and stirred at 70-80 °C for 6-6.5 h to obtain Product 4a.

[0020] Furthermore, the dosage ratios of spirocyclic carboxylic acid, DMF, 4-methylpyridine, and Product 2a are 16-18 g: 210-220 mL: 1.9-2.1 g: 86-88 g; the spirocyclic carboxylic acid is bicyclo[3.1.1]heptane-1-carboxylic acid; the dosage ratios of Product 3a, nitro-phosphoryl chloride, and ethyl acetate are 100-102 g: 39-41 g: 290-300 mL; the nitro-phosphoryl chloride is bis(2-nitrobenzyl)chlorophosphonate.

[0021] In the reaction process of Step A2, the spirocyclic carboxylic acid reacts with the epoxy group in Product 2a to obtain Product 3a containing sodium lignosulfonate, bicycloheptane, and a long-chain alkane with a hydroxyl group in the linoleic acid group; the nitro-phosphoryl chloride reacts with the hydroxyl group in Product 3a to obtain Product 4a containing sodium lignosulfonate, bicycloheptane, a long-chain alkane in the linoleic acid group, and nitro phosphate.

[0022] Step A3: Product 4a is added to a methanol solution, iron powder and ammonium chloride are added, the pH is adjusted to 5-6, and the mixture is refluxed and stirred at 50-60 °C for 3-3.5 h to obtain a flame retardant.

[0023] Furthermore, the dosage ratios of Product 4a, methanol solution, iron powder, and ammonium chloride are 150-152 g: 340-350 mL: 6-8 g: 11-13 g; the methanol solution is obtained by mixing methanol and water in a volume ratio of 4-4.5:1.

[0024] In the reaction process of Step A3, the nitro group in Product 4a is reduced to an amino group to obtain a flame retardant containing sodium lignosulfonate, bicycloheptane, a long-chain alkane in the linoleic acid group, an amino group, and phosphate.

[0025] The preparation of the modified nano-ceramic microspheres includes the following steps:

[0026] Step B1: React thiophene indazole and epichlorohydrin under the action of catalyst a to obtain product 1b; reduce the nitrocycloheptatriene-containing compound with a reducing agent to obtain product 2b; mix product 1b, product 2b, and DMSO and stir to react to obtain product 3b;

[0027] Step B2: Mix ceramic microbeads, deionized water, and ball milling media and ball mill them, then screen to obtain a dispersion system; mix the dispersion system and dispersant 1, then perform high-pressure homogenization cycling, ultrasonic-assisted dispersion, and etching agent treatment, and then carry out centrifugal separation and freeze-drying to obtain product 4b;

[0028] Step B3: Immerse product 4b in a sodium hydroxide solution for treatment to obtain pretreated ceramic microbeads; modify the surface of the pretreated ceramic microbeads with the hydrolyzed solution obtained by hydrolyzing the silane coupling agent to obtain product 5b;

[0029] Step B4: Mix product 5b, product 3b, methanol, isopropanol, and N-ethylpiperidine and stir to react to obtain modified nano-ceramic microbeads;

[0030] The preparation of the modified nano-ceramic microbeads includes the following specific steps:

[0031] Step B1: Mix thiophene indazole, epichlorohydrin, catalyst a, and toluene, then stir and react at 105 - 115 °C for 4 - 4.5 h, cool to room temperature, add an alkali solution, and continue to stir for 2 - 2.5 h to obtain product 1b; mix nitrocycloheptatriene-containing compound, toluene, acetone, and a reducing agent, and reflux and stir to react at 50 - 60 °C for 2 - 2.5 h to obtain product 2b; mix product 1b, product 2b, and DMSO, and stir to react at 50 - 60 °C for 12 - 13 h to obtain product 3b;

[0032] Further, the dosage ratios of thiophene indazole, epichlorohydrin, catalyst a, toluene, and the alkali solution are 21 - 23 g: 10 - 12 g: 2 - 3 g: 75 - 85 mL: 45 - 55 mL; the thiophene indazole is 6-(thiophen-2-yl)-1H-indazole; the catalyst a is tetrabutylammonium chloride; the alkali solution is a potassium hydroxide solution with a mass fraction of 30 - 40%; the dosage ratios of the nitrocycloheptatriene-containing compound, toluene, acetone, and the reducing agent are 19 - 21 g: 40 - 50 mL: 30 - 40 mL: 18 - 20 g; the nitrocycloheptatriene-containing compound is 2-methoxy-5-nitro-2,4,6-cycloheptatriene-1-one; the reducing agent is sodium dithionite; the dosage ratios of product 1b, product 2b, and DMSO are 32 - 34 g: 18 - 20 g: 105 - 115 mL;

[0033] During the reaction process of Step B1, the secondary amino group containing thiophene indazole undergoes ring opening and then ring closing with epichlorohydrin to obtain thiophene indazole containing an epoxy group, namely Product 1b; the nitro group of the nitrocycloheptatriene is reduced to an amino group by a reducing agent to obtain Product 2b; the epoxy group of Product 1b reacts with the amino group of Product 2b to obtain Product 3b containing thiophene, indazole, cycloheptatriene and a hydroxyl group;

[0034] Step B2: Mix ceramic microbeads, deionized water and a ball milling medium and ball mill for 48 - 60 h, then screen to obtain a dispersion system. Mix the dispersion system and Dispersant 1, and perform high-pressure homogenization cycling 10 - 15 times at 160 - 180 MPa, then perform ultrasonic-assisted dispersion for 4 - 5 h at a frequency of 30 - 40 kHz. Then add an etching agent and stir for 3 - 4 h, and then separate the particles by centrifugation and freeze-dry for 7 - 8 h to obtain Product 4b;

[0035] Furthermore, the dosage ratio of ceramic microbeads, deionized water and the ball milling medium in the dispersion system is 15 - 25 g: 60 - 70 g: 12 - 18 g; the mesh number of the sieve used for screening is 20 - 40 meshes, and the ball milling medium is 3 mm zirconia beads; the dosage ratio of the dispersion system, Dispersant 1 and the etching agent is 90 - 100 g: 0.08 - 0.10 g: 4.5 - 5.5 g; Dispersant 1 is a polycarboxylate salt; the etching agent is a hydrochloric acid solution with a concentration of 1 - 2 mol / L; the rotation speed used for centrifugal separation is 10000 - 12000 rpm;

[0036] During the reaction process of Step B2, nano-scale ceramic microbeads are obtained through high-energy ball milling, high-pressure homogenization technology, ultrasonic dispersion and chemical etching, namely Product 4b;

[0037] Step B3: Immerse Product 4b in a sodium hydroxide solution for 10 - 11 h, wash it alternately with deionized water and absolute ethanol 6 times, and dry it at 90 - 100 °C for 6 - 6.5 h to obtain pretreated ceramic microbeads; mix a silane coupling agent, deionized water and acetic acid and stir and react at room temperature for 0.5 - 1 h to obtain a hydrolysis solution; in an atmosphere of a protective gas, mix the pretreated ceramic microbeads and absolute ethanol, then drip the hydrolysis solution, and stir and react at 70 - 80 °C for 4 - 4.5 h to obtain Product 5b;

[0038] Furthermore, the dosage ratio of Product 4b and the sodium hydroxide solution is 5 - 6 g: 45 - 55 mL; the dosage ratio of the silane coupling agent, deionized water and acetic acid in the hydrolysis solution is 27 - 29 g: 120 - 130 mL: 10 - 15 mL; the silane coupling agent is 5,6-epoxyhexyltriethoxysilane; the concentration of the sodium hydroxide solution is 4 - 5 mol / L; the dosage ratio of the pretreated ceramic microbeads, absolute ethanol and the hydrolysis solution is 10 - 12 g: 140 - 150 mL: 160 - 170 mL;

[0039] During the reaction process of Step B3, sodium hydroxide solution is used to remove the surface impurities of Product 4b and activate the surface hydroxyl groups; the hydrolyzed solution obtained by hydrolyzing the silane coupling agent is used to modify the surface of the pretreated ceramic microbeads to obtain nano-ceramic microbeads with epoxy groups on the surface, namely Product 5b;

[0040] Step B4: After mixing Product 5b, Product 3b, methanol, isopropanol, and N-ethylpiperidine, reflux and stir at 115 - 120 °C for 8 - 8.5 h to obtain modified nano-ceramic microbeads;

[0041] Furthermore, the dosage ratio of Product 5b, Product 3b, methanol, isopropanol, and N-ethylpiperidine is 13 - 15 g : 52 - 54 g : 100 - 110 mL : 40 - 50 mL : 4 - 5 g;

[0042] During the reaction process of Step B4, the epoxy groups of Product 5b react with the hydroxyl groups of Product 3b to obtain nano-ceramic microbeads containing thiophene, indazole, cycloheptatriene, and hydroxyl groups, namely modified nano-ceramic microbeads;

[0043] The beneficial effects of the present invention: The present invention discloses a nano-ceramic microbead thermal insulation material and its preparation method. The nano-ceramic microbead thermal insulation material is prepared from raw materials such as silicone-acrylic emulsion, styrene-acrylic emulsion, modified nano-ceramic microbeads, silica aerogel, talcum powder, dispersant, thickener, flame retardant, and water.

[0044] The flame retardant used in the present invention is obtained by reacting sodium lignosulfonate, linoleic anhydride, bicyclo[3.1.1]heptane-1-carboxylic acid, bis(2-nitrobenzyl)chlorophosphonate, etc.; after the reaction grafting of sodium lignosulfonate, linoleic anhydride, and bicyclo[3.1.1]heptane-1-carboxylic acid, the formed linoleic acid-based alkane long chain and bicycloheptane produce a synergistic hydrophobic effect, reducing the hydrophilicity of sodium lignosulfonate, making the flame retardant meet the use requirements of low water absorption of the thermal insulation material. The spirocyclic rigid structure of bicycloheptane is beneficial to the improvement of the thermal stability of the flame retardant; the combined use of sodium lignosulfonate and bis(2-nitrobenzyl)chlorophosphonate, sodium lignosulfonate and phosphate produce an intramolecular synergistic effect, quickly forming a dense carbon layer. The amino group in the flame retardant can also form non-combustible gases to dilute combustible gases, so that the flame retardant has strong flame retardant properties; the amino group in the flame retardant can crosslink with the dispersant, enhancing the compatibility of the flame retardant and modified nano-ceramic microbeads, etc., contributing to the formation of a more uniform system, which is beneficial to the improvement of the comprehensive performance of the thermal insulation material.

[0045] The modified nano-ceramic microspheres used in the present invention are obtained by first subjecting ceramic microspheres to ultra-fine grinding, high-pressure homogenization, ultrasonic dispersion and other processes to obtain nano-scale ceramic microspheres, modifying them with a silane coupling agent, and then reacting and grafting them with 6-(thiophen-2-yl)-1H-indazole and 2-methoxy-5-nitro-2,4,6-cycloheptatriene-1-one; after modifying the obtained nano-scale ceramic microspheres with a silane coupling agent, the agglomeration property of the nano-ceramic microspheres is improved, and a multi-scale heat insulation layer is formed with talcum powder and the like, endowing the thermal insulation material with strong thermal insulation performance; after 6-(thiophen-2-yl)-1H-indazole and 2-methoxy-5-nitro-2,4,6-cycloheptatriene-1-one react and combine, thiophene, indazole and cycloheptatriene form a larger double bond conjugate system, and thiophene, indazole and cycloheptatriene synergistically endow the thermal insulation material with strong ultraviolet resistance, avoiding the situation of functional decline of the thermal insulation material caused by yellowing, powdering, cracking, etc. of styrene-acrylic emulsion and the like due to long-term exposure of the thermal insulation material to an ultraviolet irradiation environment; after 6-(thiophen-2-yl)-1H-indazole and 2-methoxy-5-nitro-2,4,6-cycloheptatriene-1-one react and graft with nano-ceramic microspheres, it also helps to form stable ultraviolet resistance; the hydroxyl groups in the modified nano-ceramic microspheres can also crosslink with the dispersant, helping to form a more uniform system, which is beneficial to the improvement of the comprehensive performance of the thermal insulation material. Detailed implementation manners

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Example 1

[0047] A flame retardant, the preparation of which comprises the following steps:

[0048] Step A1: Mix sodium lignosulfonate and linoleic anhydride, add a catalyst, reflux and stir at 115°C for 24 h to obtain a reaction solution. Then add the reaction solution to an ice-cold ethanol solution to obtain a precipitate. Wash the precipitate until neutral, and then vacuum dry at 45°C for 8 h to obtain Product 1a. Add Product 1a to ethanol, and then add an oxidant solution at 40°C and stir for 5 h to obtain Product 2a. The dosage ratio of sodium lignosulfonate, linoleic anhydride, and the catalyst is 54 g: 28 g: 3 g. The dosage ratio of the reaction solution to the ice-cold ethanol solution is 88 g: 80 mL. The ethanol solution is prepared by mixing ethanol and water in a volume ratio of 3:1. The catalyst is obtained by mixing 2-ethylimidazole and 1-methylimidazole in a mass ratio of 1:1.5. The dosage ratio of Product 1a, ethanol, and the oxidant solution is 84 g: 120 mL: 66 mL. The oxidant solution is obtained by mixing m-chloroperoxybenzoic acid and tetrahydrofuran in a dosage ratio of 19 g: 45 mL. The volume fraction of ethanol is 95%.

[0049] Step A2: In a nitrogen atmosphere, mix bicyclo[3.1.1]heptane-1-carboxylic acid and DMF and heat to 50°C. Add 4-methylpyridine and Product 2a and stir for 8 h to obtain Product 3a. Mix Product 3a, bis(2-nitrobenzyl) chlorophosphate, and ethyl acetate and reflux and stir at 70°C for 6 h to obtain Product 4a. The dosage ratio of bicyclo[3.1.1]heptane-1-carboxylic acid, DMF, 4-methylpyridine, and Product 2a is 16 g: 210 mL: 1.9 g: 86 g. The dosage ratio of Product 3a, bis(2-nitrobenzyl) chlorophosphate, and ethyl acetate is 100 g: 39 g: 290 mL.

[0050] Step A3: Add Product 4a to a methanol solution, add iron powder and ammonium chloride, adjust the pH to 5.3, and reflux and stir at 50°C for 3 h to obtain the flame retardant. The dosage ratio of Product 4a, the methanol solution, iron powder, and ammonium chloride is 150 g: 340 mL: 6 g: 11 g. The methanol solution is prepared by mixing methanol and water in a volume ratio of 4:1. Example 2

[0051] A flame retardant, the preparation of which comprises the following steps:

[0052] Step A1: Mix sodium lignosulfonate with linoleic anhydride, add a catalyst, reflux and stir at 120 °C for 24.5 h to obtain a reaction solution. Then add the reaction solution to an ice-cold ethanol solution to obtain a precipitate. Wash the precipitate until neutral, and then vacuum dry at 48 °C for 8.3 h to obtain Product 1a. Add Product 1a to ethanol, and then add an oxidant solution at 45 °C and stir for 5.3 h to obtain Product 2a. The dosage ratio of sodium lignosulfonate, linoleic anhydride, and the catalyst is 55 g: 29 g: 4 g. The dosage ratio of the reaction solution to the ice-cold ethanol solution is 90 g: 85 mL. The ethanol solution is prepared by mixing ethanol and water in a volume ratio of 3.3: 1. The catalyst is obtained by mixing 2-ethylimidazole and 1-methylimidazole in a mass ratio of 1: 1.5. The dosage ratio of Product 1a, ethanol, and the oxidant solution is 85 g: 125 mL: 67 mL. The oxidant solution is obtained by mixing m-chloroperoxybenzoic acid and tetrahydrofuran in a dosage ratio of 20 g: 50 mL. The volume fraction of ethanol is 95%.

[0053] Step A2: In a nitrogen atmosphere, mix bicyclo[3.1.1]heptane-1-carboxylic acid and DMF, heat up to 55 °C, add 4-methylpyridine and Product 2a, and stir for 8.3 h to obtain Product 3a. Mix Product 3a, bis(2-nitrobenzyl)chlorophosphonate, and ethyl acetate, and reflux and stir at 75 °C for 6.3 h to obtain Product 4a. The dosage ratio of bicyclo[3.1.1]heptane-1-carboxylic acid, DMF, 4-methylpyridine, and Product 2a is 17 g: 215 mL: 2.0 g: 87 g. The dosage ratio of Product 3a, bis(2-nitrobenzyl)chlorophosphonate, and ethyl acetate is 101 g: 40 g: 295 mL.

[0054] Step A3: Add Product 4a to a methanol solution, add iron powder and ammonium chloride, adjust the pH to 5.6, and reflux and stir at 55 °C for 3.3 h to obtain the flame retardant. The dosage ratio of Product 4a, the methanol solution, iron powder, and ammonium chloride is 151 g: 345 mL: 7 g: 12 g. The methanol solution is prepared by mixing methanol and water in a volume ratio of 4.3: 1. Example 3

[0055] A flame retardant, the preparation of which comprises the following steps:

[0056] Step A1: Mix sodium lignosulfonate and linoleic anhydride, add a catalyst, reflux and stir at 125 °C for 25 h to obtain a reaction solution. Then add the reaction solution to an ice-cold ethanol solution to obtain a precipitate. Wash the precipitate to neutrality, and then vacuum dry at 50 °C for 8.5 h to obtain Product 1a. Add Product 1a to ethanol, and then add an oxidant solution at 50 °C and stir for 5.5 h to obtain Product 2a. The dosage ratio of sodium lignosulfonate, linoleic anhydride, and the catalyst is 56 g: 30 g: 5 g. The dosage ratio of the reaction solution to the ice-cold ethanol solution is 92 g: 90 mL. The ethanol solution is prepared by mixing ethanol and water in a volume ratio of 3.5: 1. The catalyst is obtained by mixing 2-ethylimidazole and 1-methylimidazole in a mass ratio of 1: 1.5. The dosage ratio of Product 1a, ethanol, and the oxidant solution is 86 g: 130 mL: 68 mL. The oxidant solution is obtained by mixing m-chloroperbenzoic acid and tetrahydrofuran in a dosage ratio of 21 g: 55 mL. The volume fraction of ethanol is 95%.

[0057] Step A2: In a nitrogen atmosphere, mix bicyclo[3.1.1]heptane-1-carboxylic acid and DMF and heat to 60 °C. Add 4-methylpyridine and Product 2a, and stir for 8.5 h to obtain Product 3a. Mix Product 3a, bis(2-nitrobenzyl) chlorophosphonate, and ethyl acetate, and reflux and stir at 80 °C for 6.5 h to obtain Product 4a. The dosage ratio of bicyclo[3.1.1]heptane-1-carboxylic acid, DMF, 4-methylpyridine, and Product 2a is 18 g: 220 mL: 2.1 g: 88 g. The dosage ratio of Product 3a, bis(2-nitrobenzyl) chlorophosphonate, and ethyl acetate is 102 g: 41 g: 300 mL.

[0058] Step A3: Add Product 4a to a methanol solution, add iron powder and ammonium chloride, adjust the pH to 5.8, and reflux and stir at 60 °C for 3.5 h to obtain a flame retardant. The dosage ratio of Product 4a, the methanol solution, iron powder, and ammonium chloride is 152 g: 350 mL: 8 g: 13 g. The methanol solution is prepared by mixing methanol and water in a volume ratio of 4.5: 1. Example 4

[0059] A modified nano-ceramic microbead, the preparation of which comprises the following steps:

[0060] Step B1: Mix 6-(thiophen-2-yl)-1H-indazole, epichlorohydrin, tetrabutylammonium chloride, and toluene, and stir and react at 105 °C for 4 h. Cool to room temperature, add an alkali solution, and continue stirring for 2 h to obtain product 1b; mix 2-methoxy-5-nitro-2,4,6-cycloheptatrien-1-one, toluene, acetone, and sodium dithionite, and reflux and stir and react at 50 °C for 2 h to obtain product 2b; mix product 1b, product 2b, and DMSO, and stir and react at 50 °C for 12 h to obtain product 3b; the dosage ratio of 6-(thiophen-2-yl)-1H-indazole, epichlorohydrin, tetrabutylammonium chloride, toluene, and the alkali solution is 21 g: 10 g: 2 g: 75 mL: 45 mL; the alkali solution is a potassium hydroxide solution with a mass fraction of 30%; the dosage ratio of 2-methoxy-5-nitro-2,4,6-cycloheptatrien-1-one, toluene, acetone, and sodium dithionite is 19 g: 40 mL: 30 mL: 18 g; the dosage ratio of product 1b, product 2b, and DMSO is 32 g: 18 g: 105 mL;

[0061] Step B2: Mix ceramic microbeads (supplier: Shanghai Huijing Yana Nano New Materials Co., Ltd., particle size 1 - 3 microns), deionized water, and a ball milling medium, and ball mill for 48 h, then pass through a 20-mesh sieve to obtain a dispersion system. Mix the dispersion system and dispersant 1, and perform high-pressure homogenization cycling 10 times at 160 MPa, then perform ultrasonic-assisted dispersion at a frequency of 30 kHz for 4 h, then add an etching agent and stir for 3 h, and then separate the particles by centrifugation and freeze-dry for 7 h to obtain product 4b; the dosage ratio of ceramic microbeads, deionized water, and the ball milling medium in the dispersion system is 15 g: 60 g: 12 g; the ball milling medium is 3-mm zirconia beads; the dosage ratio of the dispersion system, dispersant 1, and the etching agent is 90 g: 0.08 g: 4.5 g; dispersant 1 is a polycarboxylate salt (supplier: Hubei Hongxin Ruiyu Fine Chemical Co., Ltd.); the etching agent is a hydrochloric acid solution with a concentration of 1 mol / L; the rotation speed used for centrifugation is 10,000 rpm;

[0062] Step B3: Immerse product 4b in a sodium hydroxide solution for 10 h, wash it alternately with deionized water and absolute ethanol 6 times, and dry it at 90 °C for 6 h to obtain pretreated ceramic microbeads; mix 5,6-epoxyhexyltriethoxysilane, deionized water, and acetic acid, and stir and react at room temperature for 0.5 h to obtain a hydrolysis solution; in a nitrogen atmosphere, mix the pretreated ceramic microbeads and absolute ethanol, then dropwise add the hydrolysis solution, and stir and react at 70 °C for 4 h to obtain product 5b; the dosage ratio of product 4b and the sodium hydroxide solution is 5 g: 45 mL; the dosage ratio of 5,6-epoxyhexyltriethoxysilane, deionized water, and acetic acid in the hydrolysis solution is 27 g: 120 mL: 10 mL; the concentration of the sodium hydroxide solution is 4 mol / L; the dosage ratio of the pretreated ceramic microbeads, absolute ethanol, and the hydrolysis solution is 10 g: 140 mL: 160 mL;

[0063] Step B4: Mix product 5b, product 3b, methanol, isopropanol, and N-ethylpiperidine, and then reflux and stir the mixture at 115°C for 8 h to obtain modified nano-ceramic microspheres; the dosage ratio of product 5b, product 3b, methanol, isopropanol, and N-ethylpiperidine is 13 g : 52 g : 100 mL : 40 mL : 4 g. Example 5

[0064] A kind of modified nano-ceramic microspheres, the preparation thereof comprises the following steps:

[0065] Step B1: Mix 6-(thiophen-2-yl)-1H-indazole, epichlorohydrin, tetrabutylammonium chloride, and toluene, and then stir and react the mixture at 110°C for 4.3 h. Cool to room temperature, add an alkali solution, and continue to stir for 2.3 h to obtain product 1b; mix 2-methoxy-5-nitro-2,4,6-cycloheptatriene-1-one, toluene, acetone, and sodium dithionite, and reflux and stir the mixture at 55°C for 2.3 h to obtain product 2b; mix product 1b, product 2b, and DMSO, and stir and react the mixture at 55°C for 12.5 h to obtain product 3b; the dosage ratio of 6-(thiophen-2-yl)-1H-indazole, epichlorohydrin, tetrabutylammonium chloride, toluene, and the alkali solution is 22 g : 11 g : 2.5 g : 80 mL : 50 mL; the alkali solution is a potassium hydroxide solution with a mass fraction of 35%; the dosage ratio of 2-methoxy-5-nitro-2,4,6-cycloheptatriene-1-one, toluene, acetone, and sodium dithionite is 20 g : 45 mL : 35 mL : 19 g; the dosage ratio of product 1b, product 2b, and DMSO is 33 g : 19 g : 110 mL;

[0066] Step B2: Mix ceramic microspheres (supplier: Shanghai Huijingya Nano New Materials Co., Ltd., particle size 1 - 3 microns), deionized water, and a ball-milling medium, and ball-mill for 54 h, then pass through a 20-mesh sieve to obtain a dispersion system. Mix the dispersion system and dispersant 1, and carry out high-pressure homogenization cycling 12 times at 170 MPa, then perform ultrasonic-assisted dispersion at a frequency of 30 kHz for 4.5 h, then add an etching agent and stir for 3.5 h, and then separate the particles by centrifugation and freeze-dry for 7.5 h to obtain product 4b; the dosage ratio of ceramic microspheres, deionized water, and the ball-milling medium in the dispersion system is 20 g : 65 g : 15 g; the ball-milling medium is 3-mm zirconia beads; the dosage ratio of the dispersion system, dispersant 1, and the etching agent is 95 g : 0.09 g : 5.0 g; dispersant 1 is sodium polycarboxylate (supplier: Hubei Hongxin Ruiyu Fine Chemical Co., Ltd.); the etching agent is a hydrochloric acid solution with a concentration of 1.5 mol / L; the rotation speed used for centrifugation is 11,000 rpm;

[0067] Step B3: Soak the product 4b in a sodium hydroxide solution for 10.5 h, wash it alternately with deionized water and absolute ethanol 6 times, and dry it at 95 °C for 6.3 h to obtain pretreated ceramic microspheres; Mix 5,6-epoxyhexyltriethoxysilane, deionized water, and acetic acid and stir and react at room temperature for 0.8 h to obtain a hydrolysis solution; In a nitrogen atmosphere, mix the pretreated ceramic microspheres and absolute ethanol, then dropwise add the hydrolysis solution, and stir and react at 75 °C for 4.3 h to obtain the product 5b; The dosage ratio of the product 4b to the sodium hydroxide solution is 5.5 g:50 mL; The dosage ratio of 5,6-epoxyhexyltriethoxysilane, deionized water, and acetic acid in the hydrolysis solution is 28 g:125 mL:13 mL; The concentration of the sodium hydroxide solution is 4.5 mol / L; The dosage ratio of the pretreated ceramic microspheres, absolute ethanol, and hydrolysis solution is 11 g:145 mL:165 mL;

[0068] Step B4: Mix the product 5b, the product 3b, methanol, isopropanol, and N-ethylpiperidine, and reflux and stir and react at 118 °C for 8.3 h to obtain modified nano-ceramic microspheres; The dosage ratio of the product 5b, the product 3b, methanol, isopropanol, and N-ethylpiperidine is 14 g:53 g:105 mL:45 mL:4.5 g. Example 6

[0069] A kind of modified nano-ceramic microspheres, the preparation thereof comprises the following steps:

[0070] Step B1: Mix 6-(thiophen-2-yl)-1H-indazole, epichlorohydrin, tetrabutylammonium chloride, and toluene, stir and react at 115 °C for 4.5 h, cool to room temperature, add an alkali solution, and continue to stir for 2.5 h to obtain the product 1b; Mix 2-methoxy-5-nitro-2,4,6-cycloheptatrien-1-one, toluene, acetone, and sodium dithionite, and reflux and stir and react at 60 °C for 2.5 h to obtain the product 2b; Mix the product 1b, the product 2b, and DMSO, and stir and react at 60 °C for 13 h to obtain the product 3b; The dosage ratio of 6-(thiophen-2-yl)-1H-indazole, epichlorohydrin, tetrabutylammonium chloride, toluene, and the alkali solution is 23 g:12 g:3 g:85 mL:55 mL; The alkali solution is a potassium hydroxide solution with a mass fraction of 40%; The dosage ratio of 2-methoxy-5-nitro-2,4,6-cycloheptatrien-1-one, toluene, acetone, and sodium dithionite is 21 g:50 mL:40 mL:20 g; The dosage ratio of the product 1b, the product 2b, and DMSO is 34 g:20 g:115 mL;

[0071] Step B2: Mix ceramic microbeads (supplier: Shanghai Huijing Asian Nano New Materials Co., Ltd., particle size 1 - 3 μm), deionized water, and ball-milling medium, and ball-mill for 60 h. Then, sieve through a 20-mesh sieve to obtain a dispersion system. Mix the dispersion system and dispersant 1, and perform high-pressure homogenization cycling 15 times at 180 MPa. Then, perform ultrasonic-assisted dispersion for 5 h at a frequency of 40 kHz. Next, add an etching agent and stir for 4 h. Then, separate the particles by centrifugation and freeze-dry for 8 h to obtain product 4b. The dosage ratio of ceramic microbeads, deionized water, and ball-milling medium in the dispersion system is 25 g:70 g:18 g. The ball-milling medium is 3-mm zirconia beads. The dosage ratio of the dispersion system, dispersant 1, and etching agent is 100 g:0.10 g:5.5 g. Dispersant 1 is polycarboxylate sodium salt (supplier: Hubei Hongxin Ruiyu Fine Chemical Co., Ltd.). The etching agent is a hydrochloric acid solution with a concentration of 2 mol / L. The rotation speed used for centrifugation is 12,000 rpm.

[0072] Step B3: Immerse product 4b in a sodium hydroxide solution for 11 h, wash it alternately with deionized water and absolute ethanol 6 times, and dry it at 100 °C for 6.5 h to obtain pretreated ceramic microbeads. Mix 5,6-epoxyhexyltriethoxysilane, deionized water, and acetic acid, and stir and react at room temperature for 1 h to obtain a hydrolysis solution. In a nitrogen atmosphere, mix the pretreated ceramic microbeads and absolute ethanol, then dropwise add the hydrolysis solution, and stir and react at 80 °C for 4.5 h to obtain product 5b. The dosage ratio of product 4b and the sodium hydroxide solution is 6 g:55 mL. The dosage ratio of 5,6-epoxyhexyltriethoxysilane, deionized water, and acetic acid in the hydrolysis solution is 29 g:130 mL:15 mL. The concentration of the sodium hydroxide solution is 5 mol / L. The dosage ratio of the pretreated ceramic microbeads, absolute ethanol, and hydrolysis solution is 12 g:150 mL:170 mL.

[0073] Step B4: Mix product 5b, product 3b, methanol, isopropanol, and N-ethylpiperidine, and reflux and stir and react at 120 °C for 8.5 h to obtain modified nano-ceramic microbeads. The dosage ratio of product 5b, product 3b, methanol, isopropanol, and N-ethylpiperidine is 15 g:54 g:110 mL:50 mL:5 g. Example 7

[0074] A nano-ceramic microbead thermal insulation material, comprising the following raw materials in parts by weight: 15 parts of silicon-acrylic emulsion, 15 parts of styrene-acrylic emulsion, 15 parts of modified nano-ceramic microbeads, 4 parts of silica aerogel, 10 parts of talcum powder, 1 part of dispersant, 0.5 part of thickener, 5 parts of flame retardant, and 10 parts of water; the dispersant is KH560, and the thickener is hydroxyethyl cellulose.

[0075] The preparation of the nano-ceramic microbead thermal insulation material comprises the following steps:

[0076] The silicone-acrylic emulsion (supplier: Guangzhou Shuangpu Trading Co., Ltd., 50 kg / barrel), styrene-acrylic emulsion (supplier: Guangzhou Shuangpu Trading Co., Ltd., 50 kg / barrel), and water were stirred at a speed of 600 rpm for 30 min. Then, the modified nano-ceramic microspheres obtained in Example 4, silica aerogel (supplier: Anhui Gaozhi New Energy Technology Co., Ltd.), talcum powder (supplier: Jiangyin Guangyuan Superfine Powder Co., Ltd., model: GY915), and dispersant were successively added and stirred at a speed of 2000 rpm for 1 h. Then, a thickener and the flame retardant obtained in Example 1 were added and stirred at a speed of 500 rpm for 30 min to obtain the nano-ceramic microsphere thermal insulation material. Example 8

[0077] A nano-ceramic microsphere thermal insulation material comprises the following raw materials in parts by weight: 18 parts of silicone-acrylic emulsion, 18 parts of styrene-acrylic emulsion, 20 parts of modified nano-ceramic microspheres, 5 parts of silica aerogel, 13 parts of talcum powder, 1.5 parts of dispersant, 0.8 part of thickener, 8 parts of flame retardant, and 13 parts of water; the dispersant is KH560, and the thickener is hydroxyethyl cellulose;

[0078] The preparation of the nano-ceramic microsphere thermal insulation material comprises the following steps:

[0079] The silicone-acrylic emulsion (supplier: Guangzhou Shuangpu Trading Co., Ltd., 50 kg / barrel), styrene-acrylic emulsion (supplier: Guangzhou Shuangpu Trading Co., Ltd., 50 kg / barrel), and water were stirred at a speed of 700 rpm for 35 min. Then, the modified nano-ceramic microspheres obtained in Example 5, silica aerogel (supplier: Anhui Gaozhi New Energy Technology Co., Ltd.), talcum powder (supplier: Jiangyin Guangyuan Superfine Powder Co., Ltd., model: GY915), and dispersant were successively added and stirred at a speed of 2000 rpm for 1.3 h. Then, a thickener and the flame retardant obtained in Example 2 were added and stirred at a speed of 500 rpm for 35 min to obtain the nano-ceramic microsphere thermal insulation material. Example 9

[0080] A nano-ceramic microsphere thermal insulation material comprises the following raw materials in parts by weight: 20 parts of silicone-acrylic emulsion, 20 parts of styrene-acrylic emulsion, 25 parts of modified nano-ceramic microspheres, 6 parts of silica aerogel, 15 parts of talcum powder, 2 parts of dispersant, 1 part of thickener, 10 parts of flame retardant, and 15 parts of water; the dispersant is KH560, and the thickener is hydroxyethyl cellulose;

[0081] The preparation of the nano-ceramic microsphere thermal insulation material comprises the following steps:

[0082] The silicone-acrylic emulsion (supplier: Guangzhou Shuangpu Trading Co., Ltd., 50 kg / barrel), styrene-acrylic emulsion (supplier: Guangzhou Shuangpu Trading Co., Ltd., 50 kg / barrel), and water were stirred at a speed of 800 rpm for 40 min. The modified nano-ceramic microspheres obtained in Example 6, silica aerogel (supplier: Anhui Gaozhi New Energy Technology Co., Ltd.), talcum powder (supplier: Jiangyin Guangyuan Superfine Powder Co., Ltd., model: GY915), and dispersant were successively added and stirred at a speed of 3000 rpm for 1.5 h. Then, a thickener and the flame retardant obtained in Example 3 were added and stirred at a speed of 600 rpm for 40 min to obtain the nano-ceramic microsphere thermal insulation material.

[0083] Comparative Example 1

[0084] Compared with Example 9, the linoleic anhydride in the preparation process of the flame retardant was replaced with 4-pentenyl anhydride, and the rest was exactly the same as in Example 9 to prepare the thermal insulation material.

[0085] Comparative Example 2

[0086] Compared with Example 9, the bicyclo[3.1.1]heptane-1-carboxylic acid in the preparation process of the flame retardant was replaced with p-ethylbenzoic acid, and the rest was exactly the same as in Example 9 to prepare the thermal insulation material.

[0087] Comparative Example 3

[0088] Compared with Example 9, the bis(2-nitrobenzyl) chlorophosphonate in the preparation process of the flame retardant was replaced with di-n-propyl chlorophosphate, and the rest was exactly the same as in Example 9 to prepare the thermal insulation material.

[0089] Comparative Example 4

[0090] Compared with Example 9, the product 4a in the preparation process of the flame retardant was replaced with the product 4a1 obtained by reacting the product 3a with p-nitrobenzoyl chloride, and the rest was exactly the same as in Example 9 to prepare the thermal insulation material.

[0091] Preparation of product 4a1: The product 3a prepared by the same process as the flame retardant used in Example 9 was mixed with pyridine, trimethylamine, and DMSO, and p-nitrobenzoyl chloride solution was added in an ice-water bath, and then stirred at 45 °C for 8.3 h to obtain the product 4a1; the p-nitrobenzoyl chloride solution was obtained by stirring p-nitrobenzoyl chloride in DMSO; the dosage ratios of the product 3a, pyridine, trimethylamine, DMSO, and p-nitrobenzoyl chloride solution were 151 g:0.9 g:7 g:320 mL:60 mL; the dosage ratios of p-nitrobenzoyl chloride and DMSO in the p-nitrobenzoyl chloride solution were 18 g:40 mL.

[0092] Comparative Example 5

[0093] Compared with Example 9, 6-(thiophen-2-yl)-1H-indazole in the preparation process of the modified nano-ceramic microspheres was replaced with 4-(2-thiophene)aniline, and the rest was exactly the same as in Example 9 to obtain the thermal insulation material.

[0094] Comparative Example 6

[0095] Compared with Example 9, 2-methoxy-5-nitro-2,4,6-cycloheptatrien-1-one in the preparation process of the modified nano-ceramic microspheres was replaced with p-nitroacetophenone, and the rest was exactly the same as in Example 9 to obtain the thermal insulation material.

[0096] Comparative Example 7

[0097] Compared with Example 9, the modified nano-ceramic microspheres were replaced with the addition of Product 4b and Product 3b in a mass ratio of 1:4, and the rest was exactly the same as in Example 9 to obtain the thermal insulation material.

[0098] The following is a further effect test on the thermal insulation material prepared by the present invention, and the test results are as follows.

[0099] Combustion performance: Refer to GB8624-2012 "Classification Standard for the Combustion Performance of Building Materials and Products" to classify the combustion grade of the obtained thermal insulation material;

[0100] Water absorption rate: The water absorption rate of the obtained thermal insulation material was measured by the immersion method (immersed in water at room temperature for 48 h);

[0101] Thermal conductivity: Refer to GB / T10294-2008 "Determination of Steady-State Thermal Resistance and Related Characteristics of Thermal Insulation Materials - Guarded Hot Plate Method" to measure the thermal conductivity of the obtained thermal insulation material;

[0102] Determination of resistance to artificial weathering: Tested according to GB / T9755-2014. A concrete interface agent (model: GJ-302) with a thickness of 1.5 mm was coated on a clean cement board (specification 150 mm × 70 mm × 6 mm), and then the obtained thermal insulation material with a thickness of 2 mm was coated. After curing and drying at room temperature for 7 d, specimens were obtained. Finally, the specimens were placed in an ultraviolet accelerated aging test chamber for testing. After 30 d, the surface conditions of the specimens were observed;

[0103] The results are recorded in Table 1;

[0104] Table 1: Test results

[0105]

[0106] According to the data in Table 1, the thermal insulation material of the present invention has strong fireproof, waterproof, heat-insulating and anti-aging properties. Comparing Example 9 with Comparative Example 1, it can be seen that when phthalic anhydride in the preparation process of the flame retardant is replaced with 4-pentenoyl chloride, the water absorption rate of the thermal insulation material increases and the waterproof performance decreases. Comparing Example 9 with Comparative Example 2, it can be seen that when bicyclo[3.1.1]heptane-1-carboxylic acid in the preparation process of the flame retardant is replaced with p-ethylbenzoic acid, the hydrophobicity and thermal stability of the flame retardant decrease, and the waterproof and fireproof properties of the thermal insulation material decrease. Comparing Example 9 with Comparative Example 3, it can be seen that when bis(2-nitrobenzyl) chlorophosphonate in the preparation process of the flame retardant is replaced with di-n-propyl chlorophosphate, sodium lignosulfonate and phosphate ester cannot synergistically flame retard with amino groups, and the crosslinking property between the flame retardant and the dispersant weakens, resulting in a decrease in the fireproof, waterproof, heat-insulating and anti-aging properties of the thermal insulation material. Comparing Example 9 with Comparative Example 4, it can be seen that when product 4a in the preparation process of the flame retardant is replaced with product 4a1 obtained by reacting product 3a with p-nitrobenzoyl chloride, sodium lignosulfonate and amino groups cannot synergistically flame retard with phosphate ester, resulting in a decrease in the fireproof property of the thermal insulation material. Comparing Example 9 with Comparative Example 5, it can be seen that when 6-(thiophen-2-yl)-1H-indazole in the preparation process of the modified nano-ceramic microspheres is replaced with 4-(2-thiophene)aniline, thiophene and cycloheptatriene cannot form a large double bond conjugate system with indazole, and the anti-ultraviolet property decreases, resulting in a decrease in the anti-aging property of the thermal insulation material. Comparing Example 9 with Comparative Example 6, it can be seen that when 2-methoxy-5-nitro-2,4,6-cycloheptatrien-1-one in the preparation process of the modified nano-ceramic microspheres is replaced with p-nitroacetophenone, thiophene and indazole cannot form a large double bond conjugate system with cycloheptatriene, and the anti-ultraviolet property decreases, resulting in a decrease in the anti-aging property of the thermal insulation material. Comparing Example 9 with Comparative Example 7, it can be seen that when the modified nano-ceramic microspheres are replaced with the addition of product 4b and product 3b in proportion, the agglomeration of the nano-ceramic microspheres is not improved, and 6-(thiophen-2-yl)-1H-indazole and 2-methoxy-5-nitro-2,4,6-cycloheptatrien-1-one do not graft with the nano-ceramic microspheres after reaction, which is not conducive to the improvement of the anti-ultraviolet property, and the crosslinking property with the dispersant weakens, resulting in a decrease in the heat-insulating, anti-aging, fireproof and waterproof properties of the thermal insulation material.

[0107] The above content is only an example and illustration of the concept of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined by the claims of the present invention, they should fall within the protection scope of the present invention.

Claims

1. A nano-ceramic microsphere thermal insulation material, characterized in that: It comprises the following raw materials in parts by weight: 15-20 parts of silicone-acrylic emulsion, 15-20 parts of styrene-acrylic emulsion, 15-25 parts of modified nano-ceramic microspheres, 4-6 parts of silica aerogel, 10-15 parts of talcum powder, 1-2 parts of dispersant, 0.5-1 part of thickener, 5-10 parts of flame retardant, and 10-15 parts of water; The flame retardant is prepared by the following steps: Step A1: Mix sodium lignosulfonate and linoleic anhydride and react under the action of a catalyst to obtain product 1a; oxidize product 1a with an oxidant solution to obtain product 2a; Step A2: React bicyclo[3.1.1]heptane-1-carboxylic acid with product 2a under the action of 4-methylpyridine to obtain product 3a; mix and react product 3a and bis(2-nitrobenzyl)chlorophosphonate to obtain product 4a; Step A3: Reduce product 4a with an iron powder and ammonium chloride reduction system to obtain the flame retardant; The modified nano-ceramic microspheres are prepared by the following steps: Step B1: React 6-(thiophen-2-yl)-1H-indazole with epichlorohydrin under the action of catalyst a to obtain product 1b; reduce 2-methoxy-5-nitro-2,4,6-cycloheptatrien-1-one with a reducing agent to obtain product 2b; mix and stir product 1b, product 2b, and DMSO to react to obtain product 3b; Step B2: Mix ceramic microspheres, deionized water, and ball milling media, ball mill, and then screen to obtain a dispersion system; mix the dispersion system and dispersant 1, and then perform high-pressure homogenization cycling, ultrasonic-assisted dispersion, and etching agent treatment, and then through centrifugal separation and freeze-drying to obtain product 4b; Step B3: Soak product 4b in a sodium hydroxide solution to obtain pretreated ceramic microspheres; modify the surface of the pretreated ceramic microspheres with a hydrolysis solution obtained by hydrolyzing a silane coupling agent to obtain product 5b; Step B4: Mix and stir product 5b, product 3b, methanol, isopropanol, and N-ethylpiperidine to react to obtain modified nano-ceramic microspheres.

2. The nano-ceramic microsphere thermal insulation material according to claim 1, wherein: In step A1, the oxidant solution is obtained by mixing m-chloroperbenzoic acid and tetrahydrofuran according to a dosage ratio of 19-21 g: 45-55 mL.

3. The nano-ceramic microsphere thermal insulation material according to claim 1, characterized in that: In step B2, the mesh number of the sieve used for screening is 20-40 meshes, the pressure used for high-pressure homogenization cycling is 160-180 MPa, the frequency used for ultrasonic-assisted dispersion is 30-40 kHz, and the rotation speed used for centrifugal separation is 10,000-12,000 rpm.

4. A nano-ceramic microsphere thermal insulation material according to claim 1, characterized in that: In step B2, the etching agent is a hydrochloric acid solution with a concentration of 1-2 mol / L.

5. A nano-ceramic microsphere thermal insulation material according to claim 1, characterized in that: In step B3, the preparation method of the hydrolysis solution is to mix a silane coupling agent, deionized water, and acetic acid, and stir and react at room temperature for 0.5-1 h to obtain the hydrolysis solution.

6. The nano-ceramic microsphere thermal insulation material according to claim 1, wherein: The dosage ratio of the silane coupling agent, deionized water, and acetic acid in the hydrolysis solution is 27-29 g: 120-130 mL: 10-15 mL; the silane coupling agent is 5,6-epoxyhexyltriethoxysilane.

7. A method for preparing the nano-ceramic microsphere thermal insulation material according to any one of claims 1-6, characterized in that: Stir the silicone-acrylic emulsion, styrene-acrylic emulsion, and water at a speed of 600 - 800 rpm for 30 - 40 min. Then, successively add the modified nano-ceramic microspheres, silica aerogel, talcum powder, and dispersant, and stir at a speed of 2000 - 3000 rpm for 1 - 1.5 h. Next, add the thickener and flame retardant, and stir at a speed of 500 - 600 rpm for 30 - 40 min to obtain the nano-ceramic microsphere thermal insulation material.

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