CN116120811A - Water-based acrylic resin composite modified aerogel heat-insulating fireproof coating and preparation method thereof - Google Patents

Abstract

The invention provides a water-based acrylic resin composite modified airgel heat-insulating and fire-proof coating and a preparation method thereof. Primer, composite modified airgel fireproof topcoat. Wherein the water-based epoxy resin adhesion-promoting primer includes water-based acrylic resin and temperature-controlling microcapsule powder, which is obtained by stirring, mixing and dispersing; the composite modified airgel fireproof topcoat includes silicone resin sealed modified fireproof gas Gel and high viscosity waterborne acrylate resin. Among them, organosilicon-sealed modified fire-proof airgel is introduced into alkoxysilane coupling, low-viscosity silicone resin, P-C-N source synergistic flame retardant, low boiling point fluorine-containing flame retardant through the airgel synthesis process be made of. The final coating has good adhesion, water resistance and excellent fire resistance and fire resistance.

Description

A water-based acrylic resin composite modified aerogel thermal insulation and fireproof coating and its preparation method

Technical Field

The invention belongs to the field of building materials, and particularly relates to a water-based acrylic resin composite modified aerogel heat insulation and fireproof coating and a preparation method thereof.

Background Art

Fire accidents are common nowadays, causing serious harm to people's lives and property. How to improve the thermal insulation and fire safety performance of building materials has become a top priority. The use of fire retardant coatings is an effective solution. Fire retardant coatings applied to building materials can prevent the spread of fire, isolate the fire source to prolong the ignition time of the substrate, or increase the insulation performance to delay the destruction of the building material structure. It has great application prospects.

Resin-based thermal insulation and fireproof coatings are usually made of high-temperature resistant resin as the main material, and are prepared by adding fillers that reduce density, reduce thermal conductivity, and improve high-temperature resistance. Silicone resin has excellent thermal oxidation stability, and its water resistance and heat resistance are far superior to general organic resins. It is one of the important resin matrices for preparing ablation-resistant thermal insulation coatings. However, the mechanical strength and adhesion properties of coatings prepared with silicone resin are poor, which seriously affects its application. _SiO2 aerogel has excellent fireproof and heat-insulating properties due to its microscopic pore structure. It has good prospects for use as a filler in fireproof and heat-insulating coatings. However, it is very brittle and easily broken and cracked. In addition, the infiltration of aerogel in some organic solvents will cause the aerogel pores to collapse, resulting in a serious decrease in its thermal insulation performance. It is difficult to use it directly in resin coatings.

Waterborne acrylic resin coating is a rapidly developing and widely used coating. It meets environmental protection requirements and can be modified according to the conditions of use to prepare multi-performance waterborne coatings. Acrylic resins are mostly prepared by the polymerization reaction of acrylic ester monomers. They have excellent resin matrix stability, excellent solvent resistance, good film-forming properties, excellent mechanical properties, corrosion resistance, and high weather resistance. In addition, its preparation process is easy to control, the materials are sufficient and cheap, and water is used as a diluent and cleaning agent. It is safe, flame-retardant, environmentally friendly, and has good construction performance, so it is deeply favored by the coating industry. Although waterborne acrylic resin has many excellent properties, it also has many shortcomings as a thermal insulation and fireproof coating. For example, acrylic resin has weak high temperature resistance and can burn. In addition, there are certain hydrophilic groups in waterborne acrylic resin coatings, which makes it easy to have problems such as poor water resistance in practical applications.

For example, CN 114804729 reported a steel structure fire protection board containing silica aerogel, which was prepared by raw materials in the following mass ratio: 20-40% water glass, 50-60% expanded vermiculite, 5-15% kaolin, 5-10% perlite, 5-10% aluminum hydroxide, 4-10% reinforcing fiber, 1-2% sodium fluorosilicate early strength agent, wherein the modified micron-sized silica thermal insulation filler, organosilicon-modified acrylate and organosilicon-modified water glass were chemically cross-linked and copolymerized, which significantly improved the water resistance and thermal insulation. However, this method needs to be heated and dried in a microwave kiln to form a fireproof board before it can be used, and it cannot be used as a coating, and its application range is severely limited.

In CN 115537099, 8% to 11.2% ammonium polyphosphate (phosphorus source), 5% to 7% melamine (nitrogen source), and 10% to 14% pentaerythritol (carbon source) are added to acrylic emulsion to form a P-C-N synergistic expansion flame retardant system. In addition, it is clear that water-soluble polyvinyl alcohol fiber is used as a binder to effectively reduce microcracks inside and outside the foaming structure of fire-retardant coatings. The use of steel slag powder as a film-forming base material can improve the later strength of the coating and improve the defect of easy cracking of cement-based coatings. Wollastonite powder can improve the physical and chemical properties of the coating and enhance the expansion ability and corrosion resistance of the coating. Quartz powder can improve the weather resistance of fire-retardant coatings. A mixture of polyacrylate emulsion and epoxy resin emulsion as a film-forming emulsion can improve the flexibility and impact resistance of the coating. However, the direct addition of P-C-N to ammonium polyphosphate as an acid source in water-based acrylic resin has a certain effect on the stability and strength of the acrylic resin. In addition, the solvent and acrylic polymer in the emulsion can easily infiltrate the aerogel, causing its pore structure to collapse or clog, thereby reducing its thermal insulation performance.

Summary of the invention

In view of the shortcomings of the prior art, a water-based acrylic resin composite modified aerogel thermal insulation and fire retardant coating and a preparation method thereof are now provided. The specific technical scheme is as follows:

The first aspect of the present invention is to provide a water-based acrylic resin composite modified aerogel heat insulation and fire retardant coating, wherein the water-based acrylic resin aerogel heat insulation and fire retardant composite coating comprises a water-based epoxy resin adhesion-enhancing primer and a composite modified aerogel fire retardant topcoat;

The composite modified aerogel fireproof topcoat comprises organic silicon resin sealed modified fireproof aerogel and high-viscosity water-based acrylic resin.

Specifically, the dry film thickness of the waterborne epoxy resin adhesion-enhancing primer is 10 to 100 μm; the dry film thickness of the composite modified aerogel fire-retardant topcoat is 100 μm to 10 mm.

The second aspect of the present invention is to provide a method for preparing a silicone resin enclosed modified fire-resistant aerogel, comprising the following steps:

(1) adding tetraethyl orthosilicate, water, ethanol and hydrochloric acid in a mass ratio of 1:4:14: ^10-4 for hydrolysis to obtain a tetraethyl orthosilicate hydrolyzate;

(2) adding an alkaline solution with rapid stirring to adjust the system pH to 4-6, and solidifying to obtain a gel;

(3) crushing the solidified gel into small particles, and then placing it in an ethanol solvent for solvent replacement. After multiple solvent replacements, a small molecular silane coupling agent containing alkoxysilane is added to the ethanol, and the temperature is raised and stirred for a period of time to obtain an alkoxy-terminated modified aerogel;

(4) After removing the solvent, an ethanol solution of a P-C-N source synergistic flame retardant is added, and the ethanol solvent is removed by vacuum distillation during the stirring and dispersion process, and the P-C-N source synergistic flame retardant is gradually precipitated and retained inside and on the surface of the aerogel, and then further dried to obtain a composite gel powder;

(5) Adding the composite gel powder to a low-boiling-point fluorine-containing flame retardant, stirring and dispersing the powder, and then adding a low-viscosity silicone resin, heating the powder until the alkoxy groups on the surface of the silicone resin and the aerogel react completely, and then separating and drying the powder to obtain a silicone resin-enclosed modified fire-resistant aerogel.

Specifically, the small molecule silane coupling agent containing alkoxysilane in step (3) is one or more of methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and γ-(2,3-epoxypropoxy)propyltriethoxysilane; the P-C-N source synergistic flame retardant is a mixture of ammonium polyphosphate, dipentaerythritol and melamine, and the mixing ratio is not particularly limited.

Specifically, the low boiling point fluorine-containing flame retardant in step (5) is one or more of perfluorohexanone, perfluorooctane, and perfluorohexane; and the low viscosity silicone resin is a commercially available or homemade alkoxy-terminated low viscosity silicone resin.

Preferably, the waterborne epoxy resin tackifying primer further comprises temperature-controlling microcapsule powder, the powder content of which is 10-30%, and is prepared by stirring, mixing and dispersing with the waterborne epoxy resin.

Specifically, the temperature-controlling microcapsule powder is a commercially available or homemade phase-change microcapsule with a particle size of 1 to 20 μm, a core material of one or more of docosane, octadecane, methyl stearate, and octadecyl stearate, and a phase change point of 20 to 40°C.

The third aspect of the present invention is to provide a method for preparing any of the above-mentioned water-based acrylic resin composite modified aerogel thermal insulation and fire retardant coatings, comprising the following steps:

(1) spraying a water-based epoxy resin adhesion primer on the substrate;

(2) mixing a high molecular weight water-based acrylic resin and the prepared silicone resin enclosed modified fire-retardant aerogel to obtain a composite modified aerogel fire-retardant topcoat, and spraying the mixture onto the surface of the water-based epoxy resin tackifying primer;

(3) After drying and curing, a water-based acrylic resin composite modified aerogel thermal insulation and fire retardant composite coating is obtained.

Specifically, the mixing ratio of the polymer water-based acrylic resin and the silicone resin enclosed modified fire-resistant aerogel is 1:1-10.

Specifically, the polymer water-based acrylic resin in step (2) has a molecular weight of 5000-200000; a type selected from one or more of hydroxyethyl acrylate (HEA), methacrylic acid (MMA), acrylamide (AM), glycidyl methacrylate (GMA), ethylene glycol dimethacrylate (EDGMA), allyl methacrylate, diacetone acrylamide (DAAM), adipic acid dihydrazide (ADH), and acetoacetoxyethyl methacrylate (AAEM) water-based acrylic resins; and a solid content selected from 80% to 100%.

Compared with the prior art, the present invention has the following beneficial effects:

(1) In the present invention, water-based epoxy resin is used as a tackifying primer, and the high adhesion strength of epoxy resin is utilized to improve the adhesion of the composite coating to the substrate. In addition, temperature-controlled phase-change microcapsules are added to the water-based epoxy resin tackifying primer, and the indoor temperature of the building is controlled at a suitable temperature through the heat absorption and heat release of the core material phase change in the microcapsule, which is energy-saving and environmentally friendly; at the same time, in the early stage of a fire, the phase-change microcapsules can reduce the probability of fire by absorbing heat, thereby reducing the fire hazard.

(2) The present invention introduces the P-C-N source synergistic flame retardant solid (ammonium polyphosphate, dipentaerythritol and melamine) into the aerogel by a solution precipitation method, which avoids the influence of directly adding flame retardants on the performance of water-based acrylic resin, and significantly improves the mechanical properties and stability. On the other hand, during the solvent volatilization process, a layer of solid flame retardant mixture is precipitated and attached to the internal pores of the aerogel, which supports the aerogel pores. In addition, the flame retardant principle of the P-C-N source synergistic flame retardant is that the three decompose to produce flame-retardant gas at high temperature, and at the same time, the acid source (containing P compound) and the C source react to form a certain thickness of expanded carbon layer inside the aerogel pores, and the aerogel pores are released and increased, which largely maintains the internal pore structure of the aerogel and improves the thermal insulation capacity. Moreover, since the aerogel itself has good fire-resistant and heat-insulating properties, the heat released by the P-C-N source synergistic flame retardant at high temperature inside the aerogel will not affect the organic resin with poor external fire resistance, thereby improving the flame retardant effect.

(3) In the present invention, the P-C-N source synergistic flame retardant and the low-boiling point fluorine-containing flame retardant are filled into the interior of the aerogel. When the temperature is low at the initial stage of the fire, the low-boiling point fluorine-containing flame retardant is vaporized when the externally enclosed silicone resin and water-based acrylic acid are burned by the fire. On the one hand, the internal pores of the aerogel are filled with flame-retardant gas, which greatly increases the thermal insulation capacity of the aerogel. On the other hand, the released flame-retardant gas plays a role in extinguishing the fire. When the temperature is high at the later stage of the fire, the P-C-N source synergistic flame retardant inside the aerogel absorbs heat and decomposes at high temperature to produce flame-retardant gas. Combined with the aerogel with high heat resistance and high thermal insulation performance, it has a better flame retardant effect.

(4) In the preparation process of the composite modified aerogel fireproof topcoat of the present invention, the aerogel is sealed by an organic silicone resin, a high molecular weight water-based acrylic resin is used, and no organic solvent is used, which further prevents the organic solvent and low molecular weight polymer from infiltrating the aerogel and damaging the aerogel structure. The fireproof and heat-insulating coating is made by using the composite modified aerogel fireproof topcoat, so that the coating has the function of blocking heat diffusion layer by layer, indirectly extending the heat conduction path, and providing a longer reaction time for the building materials after catching fire.

(5) In the present invention, silicone resin and aerogel with excellent water resistance and heat resistance are introduced to modify the water-based acrylic resin with poor water resistance and heat resistance, which not only maintains the mechanical properties and good film-forming properties of the water-based acrylic resin, but also improves the water resistance and heat resistance of the coating.

DETAILED DESCRIPTION

The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention is further described below in conjunction with specific embodiments, but is not intended to be a limitation of the present invention.

Example 1

1. Preparation of silicone resin enclosed modified fire-resistant aerogel:

1) adding tetraethyl orthosilicate, water, ethanol and hydrochloric acid in a molar ratio of 1:4:14: ^10-4 in a reactor protected by inert gas to hydrolyze to obtain a tetraethyl orthosilicate hydrolyzate;

2) adding an alkaline solution to the obtained mixed solution with rapid stirring to adjust the pH of the system to 5, and solidifying to obtain a gel;

3) The solidified gel was crushed into small particles, and then placed in an ethanol solvent for solvent replacement. After four solvent replacements, methyl trimethoxy (the mass ratio of silane coupling agent to aerogel was 1:1) was added to the ethanol, and the temperature was raised and stirred for 48 hours to obtain an alkoxy-terminated modified aerogel;

4) After the liquid is separated by suction filtration, ammonium polyphosphate, dipentaerythritol and melamine are added to form an ethanol solution of a P-C-N source synergistic flame retardant, and the ethanol solvent is removed by vacuum distillation during the stirring and dispersion process, and then the ethanol solvent is removed by vacuum distillation, and the P-C-N source synergistic flame retardant is gradually precipitated and retained inside and on the surface of the aerogel, and then the composite gel is further dried in a vacuum drying oven;

5) Add the composite gel powder from the previous step to perfluorohexanone, stir and disperse it completely, then add the alkoxy-terminated low-viscosity silicone resin, heat and stir to react for 48 hours, the silicone resin and the alkoxy groups on the surface of the aerogel react completely, and the low-boiling point fluorine-containing flame retardant is sealed inside; separate the liquid, and then dry it at low temperature to prepare the silicone resin-sealed modified fire-resistant aerogel.

2. Preparation of water-based acrylic resin composite modified aerogel thermal insulation and fire retardant coating sample:

1) Spray 30μm of water-based epoxy resin adhesion primer on the base layer of the rock wool board;

2) dissolving 30 parts of the silicone resin enclosed modified fireproof aerogel in 70 parts of a high-viscosity water-based acrylic resin, stirring and mixing to form a composite modified aerogel fireproof topcoat slurry;

3) Before the adhesion-enhancing primer is dry, spray the composite modified aerogel fire retardant topcoat slurry onto the primer surface until the dry film thickness of the composite modified aerogel fire retardant topcoat is 200 μm;

4) After drying, the dry film thickness of the aerogel thermal insulation and fire retardant composite coating is 200 μm, and the test is performed after curing for 7 days.

Example 2

1. Preparation of silicone resin enclosed modified fire-resistant aerogel:

1) adding tetraethyl orthosilicate, water, ethanol and hydrochloric acid in a molar ratio of 1:4:14: ^10-4 in a reactor protected by inert gas to hydrolyze to obtain a tetraethyl orthosilicate hydrolyzate;

2) adding an alkaline solution to the obtained mixed solution with rapid stirring to adjust the pH of the system to 5, and solidifying to obtain a gel;

3) The solidified gel was crushed into small particles, and then placed in an ethanol solvent for solvent replacement. After four solvent replacements, methyltrimethoxy and γ-(2,3-epoxypropoxy)propyltrimethoxysilane (the mass ratio of silane coupling agent to aerogel was 1:2) were added to the ethanol, and the temperature was raised and stirred for 48 hours to obtain an alkoxy-terminated modified aerogel;

4) After the liquid is separated by suction filtration, ammonium polyphosphate, dipentaerythritol and melamine are added to form an ethanol solution of a P-C-N source synergistic flame retardant, and the ethanol solvent is removed by vacuum distillation during the stirring and dispersion process, and then the ethanol solvent is removed by vacuum distillation, and the P-C-N source synergistic flame retardant is gradually precipitated and retained inside and on the surface of the aerogel, and then the composite gel is further dried in a vacuum drying oven;

5) Add the composite gel powder from the previous step into perfluorohexane, stir and disperse it completely, then add the alkoxy-terminated low-viscosity silicone resin, heat and stir to react for 48 hours, the silicone resin and the alkoxy groups on the surface of the aerogel react completely, and the low-boiling point fluorine-containing flame retardant is sealed inside; separate the liquid, and then dry it at low temperature to prepare the silicone resin-sealed modified fire-resistant aerogel.

2. Preparation of water-based acrylic resin composite modified aerogel thermal insulation and fire retardant coating sample:

1) Spray 20μm of water-based epoxy resin adhesion primer on the base layer of the rock wool board;

2) dissolving 40 parts of the silicone resin enclosed modified fireproof aerogel in 60 parts of a high-viscosity water-based acrylic resin, stirring and mixing to form a composite modified aerogel fireproof topcoat slurry;

3) Before the adhesion primer is dry, spray the composite modified aerogel fire retardant topcoat slurry onto the primer surface until the dry film thickness of the composite modified aerogel fire retardant topcoat is 3 mm;

4) After drying, the dry film thickness of the aerogel heat insulation and fire retardant composite coating is 3 mm, and the test is performed after curing for 7 days.

Example 3

1. Preparation of silicone resin enclosed modified fire-resistant aerogel:

1) adding tetraethyl orthosilicate, water, ethanol and hydrochloric acid in a molar ratio of 1:4:14: ^10-4 in a reactor protected by inert gas to hydrolyze to obtain a tetraethyl orthosilicate hydrolyzate;

2) adding an alkaline solution to the obtained mixed solution with rapid stirring to adjust the pH of the system to 6, and solidifying to obtain a gel;

3) The solidified gel was crushed into small particles, and then placed in an ethanol solvent for solvent replacement. After four solvent replacements, dimethyl dimethoxy and γ-(2,3-epoxypropoxy)propyl trimethoxysilane (the mass ratio of silane coupling agent to aerogel was 1:1) were added to the ethanol, and the temperature was raised and stirred for 48 hours to obtain an alkoxy-terminated modified aerogel;

4) After the liquid is separated by suction filtration, ammonium polyphosphate, dipentaerythritol and melamine are added to form an ethanol solution of a P-C-N source synergistic flame retardant, and the ethanol solvent is removed by vacuum distillation during the stirring and dispersion process, and then the ethanol solvent is removed by vacuum distillation, and the P-C-N source synergistic flame retardant is gradually precipitated and retained inside and on the surface of the aerogel, and then the composite gel is further dried in a vacuum drying oven;

5) Add the composite gel powder of the previous step into perfluorooctane, stir and disperse it completely, then add the alkoxy-terminated low-viscosity silicone resin, heat and stir to react for 48 hours, the silicone resin and the alkoxy groups on the surface of the aerogel react completely, and the low-boiling point fluorine-containing flame retardant is sealed inside; separate the liquid, and then dry it at low temperature to prepare the silicone resin-sealed modified fire-resistant aerogel.

2. Preparation of water-based acrylic resin composite modified aerogel thermal insulation and fire retardant coating sample:

1) Spray 50μm of water-based epoxy resin adhesion primer on the base layer of the rock wool board;

2) dissolving 40 parts of the silicone resin enclosed modified fireproof aerogel in 60 parts of a high-viscosity water-based acrylic resin, stirring and mixing to form a composite modified aerogel fireproof topcoat slurry;

3) Before the adhesion-enhancing primer is dry, spray the composite modified aerogel fire retardant topcoat slurry onto the primer surface until the dry film thickness of the composite modified aerogel fire retardant topcoat is 5 mm;

4) After drying, the aerogel heat insulation and fire retardant composite coating has a dry film thickness of 5 mm and is tested after curing for 7 days.

Comparative Example 1

Compared with Example 1, in Comparative Example 1, ordinary hydrophobic aerogel that has not been fireproof modified is used to replace the silicone resin enclosed modified fireproof aerogel without further modification, as follows:

1. Preparation of ordinary hydrophobic aerogel:

1) adding tetraethyl orthosilicate, water, ethanol and hydrochloric acid at a molar ratio of 1:4:14: ^10-4 for hydrolysis to obtain a tetraethyl orthosilicate hydrolyzate;

2) adding an alkaline solution to the obtained mixed solution with rapid stirring to adjust the pH of the system to 4-6, and solidifying to obtain a composite gel;

3) The solidified gel was crushed into small particles, and then placed in an ethanol solvent for solvent replacement. After four solvent replacements, the solvent inside the aerogel was replaced by ethanol from water;

4) The composite gel after solvent replacement is then placed in dimethyldisilazane with a mass twice that of the composite gel for modification for 48 hours;

5) Separate the liquid, and then grade and dry the composite gel under nitrogen hot air to prepare ordinary hydrophobic aerogel powder.

2. Preparation of aerogel thermal insulation and fire retardant coating samples:

1) Spray 30μm of water-based epoxy resin adhesion primer on the base layer of the rock wool board;

2) dissolving 30 parts of common hydrophobic aerogel in 70 parts of high-viscosity aqueous acrylate resin, stirring and mixing to form an aerogel fire-retardant topcoat slurry;

3) Before the adhesion primer is dry, spray the aerogel fire retardant topcoat slurry onto the primer surface until the dry film thickness of the aerogel fire retardant topcoat is 200 μm;

4) After drying, the dry film thickness of the aerogel thermal insulation and fire retardant composite coating is 200 μm, and the test is performed after curing for 7 days.

Comparative Example 2

Compared with Example 1, there is no adhesion-enhancing primer, as follows:

1) dissolving 30 parts of silicone resin enclosed modified fireproof aerogel in 70 parts of high viscosity waterborne acrylic resin, stirring and mixing to form aerogel fireproof topcoat slurry;

2) spraying the aerogel fire retardant topcoat slurry on the rock wool board substrate layer to a dry film thickness of 200 μm;

3) After drying, the dry film thickness of the aerogel thermal insulation and fire retardant composite coating is 200 μm, and the test is performed after curing for 7 days.

Comparative Example 3

Compared with Example 1, only tackifying primer and high-viscosity water-based acrylate resin are used, and silicone resin-sealed modified fire-retardant aerogel is not used as a coating filler. The thickness of the topcoat is the sum of the thickness of the topcoat in Comparative Example 1.

The performance tests of the samples provided in the embodiments of the present invention and the comparative examples are shown in Table 1:

According to the data in Table 1, the present invention uses a special coating design and an epoxy resin with strong adhesion to the substrate as a primer, which significantly improves the adhesion of the composite coating (the adhesion in Comparative Example 2 is increased from 1A to 5A in Example 2); and from the flame retardant time of Examples 1 and 2, it can be seen that as the thickness of the fire retardant topcoat spray increases, the flame retardant time also becomes significantly longer; in addition, the composite fire retardant modification and filling of the aerogel enables the coating to have layer-by-layer heat diffusion barrier, and the release and decomposition of the flame retardant at high temperature maintains the pore structure in the aerogel, and the thermal conductivity decreases after expansion at high temperature, and the thermal insulation is improved, which greatly prolongs the flame retardant time of the coating, providing a longer reaction time for the building material after ignition (the flame retardant time of Comparative Examples 1 and 3 is much lower than that of Example 1). At the same time, from the water resistance test results of Comparative Example 3 and Example 1, it can be seen that the aerogel and silicone resin introduced into the coating significantly improve the water resistance of the coating.

Table 1 Performance test results of samples prepared in Examples and Comparative Examples

Claims (10)

1. A water-based acrylic resin composite modified aerogel thermal insulation and fire retardant coating, characterized in that the water-based acrylic resin composite modified aerogel thermal insulation and fire retardant coating comprises a water-based epoxy resin tackifying primer and a composite modified aerogel fire retardant topcoat; the composite modified aerogel fire retardant topcoat comprises a silicone resin sealed modified fire retardant aerogel and a high-viscosity water-based acrylic resin. 2. According to claim 1, the water-based acrylic resin composite modified aerogel thermal insulation and fire-retardant coating is characterized in that the dry film thickness of the water-based epoxy resin adhesion-enhancing primer is 10 to 100 μm; the dry film thickness of the composite modified aerogel fire-retardant topcoat is 100 μm to 10 mm. 3. The water-based acrylic resin composite modified aerogel heat insulation and fire retardant coating according to claim 1, characterized in that the preparation of the silicone resin enclosed modified fire retardant aerogel comprises the following steps: (1) adding tetraethyl orthosilicate, water, ethanol and hydrochloric acid in a mass ratio of 1:4:14: ^10-4 for hydrolysis to obtain a tetraethyl orthosilicate hydrolyzate; (2) adding an alkaline solution with rapid stirring to adjust the system pH to 4-6, and solidifying to obtain a gel; (3) crushing the solidified gel into small particles, and then placing it in an ethanol solvent for solvent replacement. After multiple solvent replacements, a small molecular silane coupling agent containing alkoxysilane is added to the ethanol, and the temperature is raised and stirred for a period of time to obtain an alkoxy-terminated modified aerogel; (4) After removing the solvent, an ethanol solution of a P-C-N source synergistic flame retardant is added, and the ethanol solvent is removed by reduced pressure distillation during the stirring and dispersion process, and the P-C-N source synergistic flame retardant is gradually precipitated and retained inside and on the surface of the aerogel, and then further dried to obtain a composite gel powder; (5) Adding the composite gel powder to a low-boiling-point fluorine-containing flame retardant, stirring and dispersing the powder, and then adding a low-viscosity silicone resin, heating the powder until the alkoxy groups on the surface of the silicone resin and the aerogel react completely, and then separating and drying the powder to obtain a silicone resin-enclosed modified fire-resistant aerogel. 4. The water-based acrylic resin composite modified aerogel thermal insulation and fireproof coating according to claim 3, characterized in that the small molecule silane coupling agent containing alkoxysilane in the preparation step (3) is one or more of methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, γ-(2,3-epoxypropyloxy)propyltrimethoxysilane, and γ-(2,3-epoxypropyloxy)propyltriethoxysilane; and the P-C-N source synergistic flame retardant is a mixture of ammonium polyphosphate, dipentaerythritol and melamine. 5. The water-based acrylic resin composite modified aerogel thermal insulation and fire retardant coating according to claim 3, characterized in that the low-boiling point fluorine-containing flame retardant in the preparation step (5) is one or more of perfluorohexanone, perfluorooctane, and perfluorohexane; and the low-viscosity silicone resin is an alkoxy-terminated low-viscosity silicone resin. 6. The water-based acrylic resin composite modified aerogel heat insulation and fireproof coating according to claim 1 is characterized in that the water-based epoxy resin tackifying primer also includes temperature-controlling microcapsule powder, the powder content is 10-30%, and the powder is obtained by stirring, mixing and dispersing with the water-based epoxy resin. 7. The water-based acrylic resin composite modified aerogel thermal insulation and fire retardant coating according to claim 1 is characterized in that the temperature-controlling microcapsule powder is a phase change microcapsule with a particle size of 1 to 20 μm, a core material of one or more of docosane, octadecane, methyl stearate, and octadecyl stearate, and a phase change point of 20 to 40°C. 8. A method for preparing the waterborne acrylic resin composite modified aerogel thermal insulation and fire retardant coating according to any one of claims 1 to 7, characterized in that it comprises the following steps: (1) spraying a water-based epoxy resin adhesion primer on the substrate; (2) mixing a high molecular weight water-based acrylic resin and the prepared silicone resin enclosed modified fire-retardant aerogel to obtain a composite modified aerogel fire-retardant topcoat, and spraying the mixture onto the surface of the water-based epoxy resin tackifying primer; (3) After drying and curing, a water-based acrylic resin composite modified aerogel thermal insulation and fire retardant composite coating is obtained. 9. The method for preparing the water-based acrylic resin composite modified aerogel heat insulation and fireproof composite coating according to claim 8, characterized in that the mixing ratio of the polymer water-based acrylic resin and the prepared silicone resin enclosed modified fireproof aerogel is 1:1-10. 10. The method for preparing a water-based acrylic resin composite modified aerogel heat insulation and fireproof composite coating according to claim 8, characterized in that the molecular weight of the high molecular water-based acrylic resin in the step (2) is selected from 5000-200000, and is selected from one or more of hydroxyethyl acrylate, methacrylic acid, acrylamide, glycidyl methacrylate, ethylene glycol dimethacrylate, allyl methacrylate, diacetone acrylamide, adipic acid dihydrazide, and acetoacetoxyethyl methacrylate water-based acrylic resins; and the solid content is 80% to 100%.