Silicon nano inorganic flame-retardant thermal insulation coating and preparation method thereof

Abstract

The application relates to the technical field of paint, and particularly discloses a silicon nano inorganic flame-retardant thermal-insulation paint and a preparation method thereof. The silicon nano inorganic flame-retardant thermal-insulation paint is prepared from the following raw materials in parts by weight: 450-550 parts of a silicon propylene emulsion, 90-110 parts of pretreated silicon-based nano aerogel, 90-110 parts of pretreated titanium white powder, 38-42 parts of a film-forming aid, 7-12 parts of a composite aid, 9-11 parts of a dihydric alcohol, 1.5-2.5 parts of cellulose, 3-5 parts of a defoaming agent, 2-4 parts of a thickening agent, 0.8-1.2 parts of a neutralizing agent and 225-260 parts of water. The silicon nano inorganic flame-retardant thermal-insulation paint prepared by the application has excellent thermal insulation and flame retardance.

Description

Technical Field

[0001] This invention relates to the technical field of coatings, and in particular to a silicon nano-inorganic flame-retardant and heat-insulating coating and its preparation method. Background Technology

[0002] Nano-inorganic flame-retardant and thermal insulation coatings possess excellent properties such as high temperature resistance, non-combustibility, and environmental friendliness, making them promising for applications in building energy conservation and industrial equipment insulation. However, existing technologies often employ physical blending and functional filler stacking, leading to an irreconcilable contradiction between the coating's mechanical properties, flame-retardant properties, and thermal insulation properties.

[0003] Specifically, this manifests in two ways: First, nano-inorganic fillers have high surface energy and are prone to aggregation, resulting in weak bonding with the organic film-forming matrix. This leads to uneven dispersion and sedimentation of the fillers in the coating, creating numerous weak interfaces within the film, which severely restricts the coating's mechanical strength, durability, and the full realization of its flame-retardant / thermal insulation functions. Second, to achieve excellent thermal insulation, a large amount of lightweight porous fillers (such as aerogel) needs to be added, but this significantly reduces mechanical strength. Furthermore, the extensive introduction of traditional flame-retardant fillers, while improving the flame-retardant rating, often leads to increased coating density, decreased thermal insulation performance, and may worsen its processability and mechanical properties.

[0004] Patent application CN118271957A discloses a nano-silica synergistic flame-retardant modified coating, comprising the following components by weight: 60-80 parts polyurethane emulsion, 10-30 parts nano-silica, 5-60 parts phosphorus-containing flame-retardant modified nano-silica, 5-10 parts dispersant, 0.1-2 parts leveling agent, and 0.1-2 parts light stabilizer. The phosphorus-containing flame-retardant modified nano-silica is prepared by the following steps: S1: Nano-silica is surface-treated with a silane coupling agent to obtain silane coupling agent modified nano-silica; S2: The phosphorus-containing flame retardant is reacted with the silane coupling agent modified nano-silica in an organic solvent to obtain phosphorus-containing flame-retardant modified nano-silica; The phosphorus-containing flame retardant is selected from at least one of hexachlorocyclotriphosphazene and hexa(p-aminophenoxy)cyclotriphosphazene.

[0005] Although this technical solution attempts to improve flame retardancy by modifying nano-silica with phosphorus-containing flame retardants, it suffers from a core defect of poor flame retardant performance. On the one hand, the polyurethane emulsion matrix itself has limited high-temperature resistance, which fundamentally limits the flame-retardant load-bearing capacity of the coating. On the other hand, this technical solution relies solely on a single phosphorus-containing flame retardant to modify nano-silica, and its modification of nanofillers focuses on introducing flame-retardant functions, rather than fundamentally strengthening the interfacial bonding between the filler and the matrix. It also fails to solve the problem of easy agglomeration of the nanofillers themselves, and the flame-retardant components cannot form a continuous and effective flame-retardant network. Summary of the Invention

[0006] In order to overcome the technical bottlenecks in the prior art, such as the easy agglomeration of nano-inorganic fillers, weak interfacial bonding with the matrix, and the resulting difficulty in synergistic improvement of the flame retardant and thermal insulation properties of coatings, this application provides a silicon nano-inorganic flame retardant and thermal insulation coating and its preparation method.

[0007] The specific technical solution provided in this application is as follows:

[0008] A silicon nano-inorganic flame-retardant and thermal insulation coating, prepared by weight of the following raw materials:

[0009] The composition includes: 450-550 parts silicone-acrylic emulsion, 90-110 parts pretreated silicone-based nano-aerogel, 90-110 parts pretreated titanium dioxide, 38-42 parts film-forming aid, 7-12 parts composite aid, 9-11 parts diols, 1.5-2.5 parts cellulose, 3-5 parts defoamer, 2-4 parts thickener, 0.8-1.2 parts neutralizer, and 225-260 parts water.

[0010] The pretreated silicon-based nano-aerogel was prepared by the following method: after vacuum-assisted impregnation with a pre-hydrolyzed solution of dihydroxy polydimethylsiloxane, short alkyl chain silane and long alkyl chain silane, it was then subjected to gradient temperature curing treatment.

[0011] The pretreated titanium dioxide is prepared by the following method: first, it is silanized on the surface by a silane coupling agent containing double bonds, and then it is surface copolymerized and grafted with a vinyl-containing phosphorus compound, a vinyl-containing bromine compound and a vinyl-containing polyether monomer.

[0012] In this technical solution, silicone-acrylic emulsion is used as the film-forming matrix, which has good compatibility with the pretreated functional fillers, providing a stable substrate for coating formation and synergistic performance of flame retardant and thermal insulation functions. Silicon-based nano-aerogels are vacuum-assisted impregnated with a pre-hydrolyzed solution of dihydroxy polydimethylsiloxane, short-chain silanes, and long-chain silanes, and then cured in situ within their porous framework by gradient temperature increase to construct a chemically bonded cross-linked network, maximizing the preservation of the porous structure to ensure thermal insulation performance while improving structural stability. Titanium dioxide is silanized and anchored to vinyl groups, then copolymerized and grafted with vinyl-containing phosphorus compounds, vinyl-containing bromine compounds, and vinyl-containing polyether monomers, endowing it with flame retardant function and interfacial compatibility. Combined with various auxiliary components to optimize construction and system stability, the synergistic optimization of the coating's flame retardant and thermal insulation performance is ultimately achieved.

[0013] Preferably, the film-forming aid is a dodecyl alcohol ester.

[0014] Preferably, the diol is propylene glycol.

[0015] Preferably, the compound additives include bactericides, antifungal and antialgae agents, preservatives, dispersants, and wetting agents.

[0016] Preferably, the preparation method of the pretreated silicon-based nano-aerogel includes the following steps:

[0017] S11: Add dihydroxy polydimethylsiloxane, short-chain silane and long-chain silane to an aqueous ethanol solution, mix well, adjust the pH to 4.0~5.0, heat to 50~70℃, and pre-hydrolyze for 2~4 hours to obtain a pre-hydrolyzed solution;

[0018] S12: The silicon-based nano-aerogel is immersed in a pre-hydrolyzed solution and kept at -0.1 to -0.08 MPa for 50 to 70 min. After restoring to normal pressure, the temperature is raised to 50 to 70 °C and immersed for 4 to 6 h. After solid-liquid separation and drying, the temperature is gradually increased to solidify the aerogel. The temperature range is 80 to 165 °C and the time is 7 to 11 h. After cooling, the aerogel is washed and dried to obtain the pretreated silicon-based nano-aerogel.

[0019] Preferably, the specific steps of the gradient temperature curing are as follows: first, heat to 80~90℃ and keep warm for 3~5 hours, then continue to heat to 155~165℃ and keep warm for 4~6 hours.

[0020] Preferably, the mass ratio of the dihydroxy polydimethylsiloxane, short alkyl chain silane, long alkyl chain silane and silicon-based nanoaerogel is (10~20):(3~7):(5~15):100.

[0021] Preferably, in step S11, the total mass fraction of dihydroxypolydimethylsiloxane, short-chain silane and long-chain silane in the ethanol aqueous solution is controlled to be about 5% to 10%.

[0022] In this technical solution, a pre-hydrolyzed solution of dihydroxy polydimethylsiloxane, short-chain silane, and long-chain silane is used to sequentially impregnate the silicon-based nano-aerogel under vacuum and atmospheric pressure to ensure that the pre-hydrolyzed solution fully penetrates into the porous structure of the aerogel. After gradient temperature curing treatment, a stable chemical bond is formed with the aerogel framework, thereby improving the structural stability of the silicon-based nano-aerogel while preserving its original porous structure to the maximum extent.

[0023] Preferably, the short alkyl chain silane is methyltrimethoxysilane or ethyltriethoxysilane.

[0024] Preferably, the long alkyl chain silane is isobutyltriethoxysilane or octyltriethoxysilane.

[0025] In this technical solution, dihydroxy polydimethylsiloxane provides flexible chain segments to maintain the integrity of the porous structure; short alkyl chain silanes construct dense cross-linking nodes with small steric hindrance to ensure the stability of the structure; long alkyl chain silanes reduce the surface energy of the system and optimize the dispersibility. The three work together to construct a flexible organosilicon network, providing structural support for the uniform distribution of flame retardant components.

[0026] Preferably, the method for preparing the pretreated titanium dioxide includes the following steps:

[0027] S21: Disperse titanium dioxide in an aqueous ethanol solution, add a silane coupling agent containing double bonds, adjust the pH to 4.0~5.0, heat to 50~70℃, react for 4~6h, cool, separate the solid and liquid, wash, and dry to obtain silanized titanium dioxide.

[0028] S22: Under an inert atmosphere, silanized titanium dioxide is dispersed in a mixed solvent, and a vinyl-containing phosphorus compound, a vinyl-containing bromine compound, and a vinyl-containing polyether monomer are added and mixed evenly. The mixture is heated to 70-80°C, an initiator is added, and the reaction is carried out for 6-10 hours. After cooling, washing, and drying, pretreated titanium dioxide is obtained.

[0029] Preferably, the mixed solvent includes isopropanol and toluene.

[0030] Preferably, the mass ratio of the double-bonded silane coupling agent, the vinyl-containing phosphorus compound, the vinyl-containing bromine compound, the vinyl-containing polyether monomer, and the titanium dioxide is (12~15):(3~5):(3~5):(2~4):100.

[0031] In this technical solution, titanium dioxide is silanized and anchored to vinyl groups, which triggers the copolymerization and grafting of three monomers, and directionally introduces phosphorus, bromine flame retardant elements and polyether segments. This not only endows it with high-efficiency flame retardant function, but also improves its compatibility with the coating system, avoids agglomeration leading to uneven distribution of flame retardant components, and lays the foundation for the synergistic optimization of flame retardant and thermal insulation performance.

[0032] Preferably, the vinyl-containing phosphorus compound is 2-methyl-2-acrylate-2-hydroxyethyl phosphate or diethyl vinylphosphonate.

[0033] Preferably, the vinyl-containing bromine compound is pentabromobenzyl acrylate.

[0034] Preferably, the vinyl-containing polyether monomer is polyethylene glycol methacrylate or allyl polyethylene glycol.

[0035] Preferably, the initiator is azobisisobutyronitrile.

[0036] Preferably, the amount of the initiator is 1% to 2% of the total mass of the vinyl-containing phosphorus compound, the vinyl-containing bromide compound, and the vinyl-containing polyether monomer.

[0037] Preferably, the silicon nano-inorganic flame-retardant and thermal insulation coating further includes 5-8 parts by weight of silanized flexible organic fibers.

[0038] Preferably, the method for preparing the silanized flexible organic fiber includes the following steps:

[0039] Flexible organic fibers are dispersed in an ethanol aqueous solution, and silane coupling agent KH550 or KH560 is added to adjust the pH to 4.0~5.0. The temperature is raised to 60~70℃ and the reaction is carried out for 4~6 hours. After solid-liquid separation, washing and drying, silanized flexible organic fibers are obtained.

[0040] Preferably, the flexible organic fiber is aramid pulp.

[0041] Preferably, the mass fraction of silane coupling agent KH550 or silane coupling agent KH560 in the ethanol aqueous solution is controlled to be 2%~3%.

[0042] In this technical solution, the silanized flexible organic fiber has good compatibility with each component, and constructs a three-dimensional interwoven network inside the coating. Through physical barrier effect, it delays the spread of flame and heat transfer, and works synergistically with other functional components to evenly improve the flame retardant and heat insulation performance of the coating.

[0043] Preferably, the silicon nano-inorganic flame-retardant and thermal insulation coating further includes 2-4 parts by weight of organically modified sheet reinforcement material.

[0044] Preferably, the method for preparing the organically modified layered reinforcing material includes the following steps:

[0045] S31: Dissolve hexadecyltrimethylammonium bromide in water to obtain an organic ammonium solution;

[0046] S32: Disperse the sheet reinforcement material in water, heat to 75~85℃, add the organic ammonium solution, mix for 3~4 hours, cool, separate solid and liquid, wash, and dry to obtain the organic modified sheet reinforcement material.

[0047] Preferably, the mass ratio of the hexadecyltrimethylammonium bromide to the lamellar reinforcement material is (0.1~0.2):1.

[0048] Preferably, the layered reinforcing material is montmorillonite or mica flakes.

[0049] In this technical solution, the layered reinforcing material is uniformly dispersed in the coating and works synergistically with silanized flexible organic fibers, pretreated titanium dioxide, and pretreated silicon-based nano-aerogel to construct a multi-layer physical barrier network, which delays oxygen and heat transfer to optimize thermal insulation and flame retardant performance.

[0050] Secondly, this application also provides a method for preparing a silicon nano-inorganic flame-retardant and thermal insulation coating, comprising the following steps:

[0051] Cellulose, diols, composite additives and some water are mixed evenly, pretreated titanium dioxide, pretreated silicon-based nano aerogel and some defoamer are added and mixed evenly, silicone acrylic emulsion and film-forming aid are added and mixed evenly, thickener, remaining water, neutralizer and remaining defoamer are added and mixed evenly to obtain silicon nano inorganic flame retardant and heat insulation coating.

[0052] In this technical solution, the following steps are taken: First, a stable system is constructed using cellulose, diols, composite additives, and a portion of water. Then, pre-treated fillers and a portion of defoamer are added to avoid uneven dispersion, ensure the integrity of the thermal insulation filler structure and the uniformity of the flame-retardant components, and suppress bubbles. Subsequently, silicone-acrylic emulsion and other components are added to ensure fusion and adjust the viscosity of the system. Finally, a coating with uniform components, a stable system, and good workability is obtained, while retaining the flame-retardant and thermal insulation functions of the fillers, ensuring the coating's formation and overall performance.

[0053] Preferably, the step of adding silanized flexible organic fibers is included before adding pretreated titanium dioxide.

[0054] Preferably, before adding pretreated titanium dioxide, the step further includes adding an organically modified layered reinforcing material.

[0055] In summary, this application has the following beneficial effects:

[0056] This application enhances the structure by forming a cross-linked network inside and on the surface of silicon-based nano-aerogels, thereby improving structural stability while maintaining high porosity to ensure thermal insulation performance. Multifunctional polymers are brush-grafted onto the surface of titanium dioxide, integrating flame retardancy and interfacial compatibility. Optionally, a multi-layered physical barrier network is constructed by combining silanized flexible organic fibers and organically modified sheet reinforcement materials to achieve a strong chemical bond with the silicone-acrylic emulsion matrix. Ultimately, the coating simultaneously possesses low thermal conductivity, high flame retardancy rating, and good construction and storage stability, successfully overcoming the technical bottleneck of the prior art where flame retardancy and thermal insulation performance are difficult to improve synergistically. Detailed Implementation

[0057] The present application will be further described in detail below with reference to the embodiments.

[0058] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0059] In an aqueous ethanol solution, the volume ratio of ethanol to deionized water is 3:1.

[0060] In the mixed solvent, the volume ratio of isopropanol to toluene is 1:1;

[0061] The solid content of the silicone-acrylic emulsion is approximately 47±1%;

[0062] The titanium dioxide is rutile titanium dioxide R-996, with a particle size distribution of 0.2~0.5μm;

[0063] The bactericide is Hoffmann QB-20; the antifungal and antialgae agent is benzisothiazolinone and benzimidazole in a mass ratio of 1:1; the preservative is Hoffmann Defros BM; the dispersant is sodium polycarboxylate; the wetting agent is Dow BD-109; the defoamer is Dow AFE-1410; the thickener is Dow TT-935; the cellulose is hydroxyethyl cellulose 481; and the neutralizing agent is Dow AMP-95 multifunctional additive.

[0064] Preparation Examples 1-3: Pretreated Silicon-based Nanoaerogels

[0065] Preparation Example 1

[0066] The preparation method of the pretreated silicon-based nano-aerogel in this example includes the following steps:

[0067] S11: Add 50g of dihydroxy polydimethylsiloxane, 15g of methyltrimethoxysilane and 25g of isobutyltriethoxysilane to 1700g of ethanol aqueous solution, mix well, adjust the pH to 5.0 with 8% acetic acid by mass, heat to 50℃, and pre-hydrolyze at a constant temperature for 4h to obtain pre-hydrolyzed solution.

[0068] S12: Immerse 500g of silica nano-aerogel in a pre-hydrolyzed solution, stir and mix at 200rpm for 15min, seal and evacuate to -0.1MPa, maintain for 70min; slowly restore to normal pressure (1 standard atmosphere), heat to 50℃, immerse for 6h, filter, vacuum dry at 60℃ for 8h, then perform gradient temperature curing, first heat to 80℃, hold for 5h, then heat to 155℃, hold for 6h, cool to room temperature, wash 3 times with anhydrous ethanol, vacuum dry at 80℃ to constant weight, to obtain pretreated silica-based nano-aerogel.

[0069] Preparation Example 2

[0070] The preparation method of the pretreated silicon-based nano-aerogel in this example includes the following steps:

[0071] S11: Add 75g of dihydroxy polydimethylsiloxane, 25g of methyltrimethoxysilane and 50g of octyltriethoxysilane to 1850g of ethanol aqueous solution, mix well, adjust the pH to 4.5 with 8% acetic acid by mass, heat to 60℃, and pre-hydrolyze at a constant temperature for 3h to obtain pre-hydrolyzed solution.

[0072] S12: Immerse 500g of silica nano-aerogel in a pre-hydrolyzed solution, stir and mix at 200rpm for 15min, seal and evacuate to -0.09MPa, hold for 60min; slowly restore to normal pressure (1 standard atmosphere), heat to 60℃, immerse for 5h, filter, vacuum dry at 60℃ for 8h, then perform gradient temperature curing, first heat to 85℃, hold for 4h, then heat to 160℃, hold for 5h, cool to room temperature, wash 3 times with anhydrous ethanol, vacuum dry at 80℃ to constant weight, to obtain pretreated silica-based nano-aerogel.

[0073] Preparation Example 3

[0074] The preparation method of the pretreated silicon-based nano-aerogel in this example includes the following steps:

[0075] S11: Add 100g of dihydroxy polydimethylsiloxane, 35g of ethyltriethoxysilane and 75g of octyltriethoxysilane to 1900g of ethanol aqueous solution, mix well, adjust the pH to 4.0 with 8% acetic acid by mass, heat to 70℃, and pre-hydrolyze at a constant temperature for 2h to obtain pre-hydrolyzed solution.

[0076] S12: Immerse 500g of silica nano-aerogel in a pre-hydrolyzed solution, stir and mix at 200rpm for 15min, seal and evacuate to -0.08MPa, hold for 50min; slowly restore to normal pressure (1 standard atmosphere), heat to 70℃, immerse for 4h, filter, vacuum dry at 60℃ for 8h, then perform gradient temperature curing, first heat to 90℃, hold for 3h, then heat to 165℃, hold for 4h, cool to room temperature, wash 3 times with anhydrous ethanol, vacuum dry at 80℃ to constant weight, to obtain pretreated silica-based nano-aerogel.

[0077] Preparation Examples 4-6: Pretreated Titanium Dioxide

[0078] Preparation Example 4

[0079] The preparation method of the pretreated titanium dioxide in this example includes the following steps:

[0080] S21: Add 500g of titanium dioxide to 2500g of ethanol aqueous solution, ultrasonically disperse for 30min at 200W and 20kHz, add 60g of vinyltrimethoxysilane, stir and mix at 200rpm for 10min, adjust the pH to 5.0 with 8% acetic acid, heat to 50℃, react for 6h, cool to room temperature, centrifuge, wash 3 times with deionized water, and vacuum dry at 80℃ for 12h to obtain silanized titanium dioxide;

[0081] S22: Under a nitrogen atmosphere, silanized titanium dioxide was added to 1500 mL of mixed solvent and ultrasonically dispersed for 20 min at a power of 200 W and a frequency of 20 kHz. Then, 15 g of 2-methyl-2-acrylate-2-hydroxyethyl ester phosphate, 15 g of pentabromobenzyl acrylate, and 10 g of polyethylene glycol methacrylate were added. The mixture was stirred and mixed evenly at a speed of 200 rpm. The temperature was raised to 70 °C, and an azobisisobutyronitrile solution (0.8 g of azobisisobutyronitrile mixed with 10 mL of isopropanol) was slowly added dropwise. The reaction was carried out for 10 h, cooled to room temperature, centrifuged, washed three times with anhydrous ethanol, and vacuum dried at 80 °C to constant weight to obtain pretreated titanium dioxide.

[0082] Preparation Example 5

[0083] The preparation method of the pretreated titanium dioxide in this example includes the following steps:

[0084] S21: Add 500g of titanium dioxide to 2100g of ethanol aqueous solution, ultrasonically disperse for 30min at 200W and 20kHz, add 65g of vinyltrimethoxysilane, stir and mix at 200rpm for 10min, adjust the pH to 4.5 with 8% acetic acid, heat to 60℃, react for 5h, cool to room temperature, centrifuge, wash three times with deionized water, and vacuum dry at 80℃ for 12h to obtain silanized titanium dioxide;

[0085] S22: Under a nitrogen atmosphere, silanized titanium dioxide was added to 1500 mL of a mixed solvent and ultrasonically dispersed for 20 min at a power of 200 W and a frequency of 20 kHz. Then, 20 g of diethyl vinylphosphonate, 20 g of pentabromobenzyl acrylate, and 15 g of allyl polyethylene glycol were added. The mixture was stirred at 200 rpm until homogeneous. The temperature was raised to 75 °C, and an azobisisobutyronitrile solution (0.8 g of azobisisobutyronitrile mixed with 10 mL of isopropanol) was slowly added dropwise. The reaction was carried out for 8 h, cooled to room temperature, centrifuged, washed three times with anhydrous ethanol, and vacuum dried at 80 °C to constant weight to obtain pretreated titanium dioxide.

[0086] Preparation Example 6

[0087] The preparation method of the pretreated titanium dioxide in this example includes the following steps:

[0088] S21: Add 500g of titanium dioxide to 1800g of ethanol aqueous solution, ultrasonically disperse for 30min at 200W and 20kHz, add 75g of vinyltrimethoxysilane, stir and mix at 200rpm for 10min, adjust the pH to 4.0 with 8% acetic acid, heat to 70℃, react for 4h, cool to room temperature, centrifuge, wash three times with deionized water, and vacuum dry at 80℃ for 12h to obtain silanized titanium dioxide;

[0089] S22: Under a nitrogen atmosphere, silanized titanium dioxide was added to 1500 mL of mixed solvent and ultrasonically dispersed for 20 min at a power of 200 W and a frequency of 20 kHz. Then, 25 g of 2-methyl-2-acrylate-2-hydroxyethyl ester phosphate, 25 g of pentabromobenzyl acrylate, and 20 g of polyethylene glycol methacrylate were added. The mixture was stirred and mixed evenly at a speed of 200 rpm. The temperature was raised to 80 °C, and an azobisisobutyronitrile solution (0.7 g of azobisisobutyronitrile mixed with 10 mL of isopropanol) was slowly added dropwise. The reaction was carried out for 6 h, cooled to room temperature, centrifuged, washed three times with anhydrous ethanol, and vacuum dried at 80 °C to constant weight to obtain pretreated titanium dioxide.

[0090] Example 1

[0091] The silicon nano-inorganic flame-retardant and thermal insulation coating of this embodiment is prepared from the following raw materials:

[0092] 450g silicone-acrylic emulsion, 90g pretreated silicone-based nano-aerogel, 90g pretreated titanium dioxide, 38g dodecyl alcohol ester, 7g composite additives, 9g propylene glycol, 1.5g cellulose, 3g defoamer, 2g thickener, 0.8g neutralizer, 225g deionized water;

[0093] The pretreated silicon-based nano-aerogel was from Preparation Example 1; the pretreated titanium dioxide was from Preparation Example 4; and the composite additives included 0.8g of bactericide, 1.2g of antifungal and antialgae agent, 0.8g of preservative, 3g of dispersant, and 1.2g of wetting agent.

[0094] The preparation method of the silicon nano-inorganic flame-retardant and heat-insulating coating in this embodiment includes the following steps:

[0095] Add 75% of the mass of deionized water to a mixing tank, start stirring, and adjust the speed to 300 rpm. Then slowly add cellulose and propylene glycol, and stir for 20 minutes. Continue stirring at 300 rpm, add composite additives, and stir for 15 minutes. Add 50% of the mass of pretreated titanium dioxide, pretreated silicon-based nano aerogel, and defoamer, adjust the speed to 800 rpm, and stir for 30 minutes. Adjust the speed to 300 rpm, slowly add silicone-acrylic emulsion, and stir for 15 minutes. Add dodecyl alcohol ester, and stir for 10 minutes. Slowly add thickener adjusted to a paste state with deionized water and the remaining deionized water, and stir for 15 minutes. Add neutralizer and the remaining defoamer, adjust the speed to 200 rpm, and stir for 10 minutes to obtain silicon nano inorganic flame-retardant thermal insulation coating.

[0096] Example 2

[0097] The silicon nano-inorganic flame-retardant and thermal insulation coating of this embodiment is prepared from the following raw materials:

[0098] 500g silicone-acrylic emulsion, 100g pretreated silicone-based nano-aerogel, 100g pretreated titanium dioxide, 40g dodecyl alcohol ester, 10g composite additive, 10g propylene glycol, 2g cellulose, 4g defoamer, 3g thickener, 1g neutralizer, 245g deionized water.

[0099] The pretreated silicon-based nano-aerogel was from Preparation Example 2; the pretreated titanium dioxide was from Preparation Example 5; and the composite additives included 1.1g of bactericide, 1.7g of antifungal and antialgae agent, 1.1g of preservative, 4.3g of dispersant, and 1.8g of wetting agent.

[0100] The preparation method of the silicon nano-inorganic flame-retardant and heat-insulating coating in this embodiment includes the following steps:

[0101] Add 80% of the mass of deionized water to a mixing tank, start stirring, and adjust the speed to 300 rpm. Then slowly add cellulose and propylene glycol, and stir for 20 minutes. Continue stirring at 300 rpm, add composite additives, and stir for 15 minutes. Add 50% of the mass of pretreated titanium dioxide, pretreated silicon-based nano aerogel, and defoamer, adjust the speed to 800 rpm, and stir for 30 minutes. Adjust the speed to 300 rpm, slowly add silicone-acrylic emulsion, and stir for 15 minutes. Add dodecyl alcohol ester, and stir for 10 minutes. Slowly add thickener adjusted to a paste state with deionized water and the remaining deionized water, and stir for 15 minutes. Add neutralizer and the remaining defoamer, adjust the speed to 200 rpm, and stir for 10 minutes to obtain silicon nano inorganic flame-retardant thermal insulation coating.

[0102] Example 3

[0103] The silicon nano-inorganic flame-retardant and thermal insulation coating of this embodiment is prepared from the following raw materials:

[0104] 550g silicone-acrylic emulsion, 110g pretreated silicone-based nano-aerogel, 110g pretreated titanium dioxide, 42g dodecyl alcohol ester, 12g composite additives, 11g propylene glycol, 2.5g cellulose, 5g defoamer, 4g thickener, 1.2g neutralizer, and 260g deionized water.

[0105] The pretreated silicon-based nano-aerogel was from Preparation Example 3; the pretreated titanium dioxide was from Preparation Example 6; and the composite additives included 1.4g of bactericide, 2.1g of antifungal and antialgae agent, 1.4g of preservative, 5.1g of dispersant and 2.0g of wetting agent.

[0106] The preparation method of the silicon nano-inorganic flame-retardant and heat-insulating coating in this embodiment includes the following steps:

[0107] Add 80% of the mass of deionized water to a mixing tank, start stirring, and adjust the speed to 300 rpm. Then slowly add cellulose and propylene glycol, and stir for 20 minutes. Continue stirring at 300 rpm, add composite additives, and stir for 15 minutes. Add 50% of the mass of pretreated titanium dioxide, pretreated silicon-based nano aerogel, and defoamer, adjust the speed to 800 rpm, and stir for 30 minutes. Adjust the speed to 300 rpm, slowly add silicone-acrylic emulsion, and stir for 15 minutes. Add dodecyl alcohol ester, and stir for 10 minutes. Slowly add thickener adjusted to a paste state with deionized water and the remaining deionized water, and stir for 15 minutes. Add neutralizer and the remaining defoamer, adjust the speed to 200 rpm, and stir for 10 minutes to obtain silicon nano inorganic flame-retardant thermal insulation coating.

[0108] Example 4

[0109] The silicon nano-inorganic flame-retardant and thermal insulation coating of this embodiment is prepared from the following raw materials:

[0110] 500g silicone-acrylic emulsion, 100g pretreated silicone-based nano-aerogel, 100g pretreated titanium dioxide, 40g dodecyl alcohol ester, 10g composite additives, 10g propylene glycol, 2g cellulose, 4g defoamer, 3g thickener, 1g neutralizer, 5g silanized flexible organic fiber, 251g deionized water.

[0111] Among them, the pretreated silicon-based nano-aerogel came from Preparation Example 2; the pretreated titanium dioxide came from Preparation Example 5; the composite additives included 1.1g of bactericide, 1.7g of antifungal and antialgae agent, 1.1g of preservative, 4.3g of dispersant and 1.8g of wetting agent;

[0112] The preparation method of silanized flexible organic fibers includes the following steps:

[0113] 10g of aramid pulp was added to 100g of ethanol aqueous solution and ultrasonically dispersed for 20min at 200W and 20kHz. Then, 2g of silane coupling agent KH550 was added and stirred at 200rpm for 10min. The pH was adjusted to 5.0 with 8% acetic acid by mass, the temperature was raised to 60℃, and the reaction was carried out for 6h. After cooling to room temperature, the mixture was centrifuged, washed twice with deionized water and once with anhydrous ethanol, and vacuum dried at 80℃ to constant weight to obtain silanized flexible organic fiber.

[0114] The aramid pulp has a diameter of 0.5~2μm and a length of 50~200μm.

[0115] The preparation method of the silicon nano-inorganic flame-retardant and heat-insulating coating in this embodiment includes the following steps:

[0116] Add 80% of the mass of deionized water to a mixing tank, start stirring, and adjust the speed to 300 rpm. Then slowly add cellulose and propylene glycol, and stir for 20 minutes. Continue stirring at 300 rpm, add composite additives, and stir for 15 minutes. Add 50% of the mass of silanized flexible organic fiber, pretreated titanium dioxide, pretreated silicon-based nano aerogel, and defoamer, adjust the speed to 800 rpm, and stir for 30 minutes. Adjust the speed to 300 rpm, slowly add silicone-acrylic emulsion, and stir for 15 minutes. Add dodecyl alcohol ester, and stir for 10 minutes. Slowly add thickener adjusted to a paste state with deionized water and the remaining deionized water, and stir for 15 minutes. Add neutralizer and the remaining defoamer, adjust the speed to 200 rpm, and stir for 10 minutes to obtain silicon nano inorganic flame-retardant thermal insulation coating.

[0117] Example 5

[0118] The difference between this embodiment and embodiment 4 is that:

[0119] The silicon nano-inorganic flame-retardant and thermal insulation coating of this embodiment is prepared from the following raw materials:

[0120] 500g silicone-acrylic emulsion, 100g pretreated silicone-based nano-aerogel, 100g pretreated titanium dioxide, 40g dodecyl alcohol ester, 10g composite additives, 10g propylene glycol, 2g cellulose, 4g defoamer, 3g thickener, 1g neutralizer, 8g silanized flexible organic fiber, 254g deionized water.

[0121] The preparation method of silanized flexible organic fibers includes the following steps:

[0122] 10g of aramid pulp was added to 100g of ethanol aqueous solution and ultrasonically dispersed for 20min at 200W and 20kHz. Then, 3g of silane coupling agent KH550 was added and stirred at 200rpm for 10min. The pH was adjusted to 4.0 with 8% acetic acid by mass, the temperature was raised to 70℃, and the reaction was carried out for 4h. After cooling to room temperature, the mixture was centrifuged, washed twice with deionized water and once with anhydrous ethanol, and vacuum dried at 80℃ to constant weight to obtain silanized flexible organic fiber.

[0123] The aramid pulp has a diameter of 0.5~2μm and a length of 50~200μm.

[0124] The rest is the same as in Example 4.

[0125] Example 6

[0126] The difference between this embodiment and embodiment 5 is as follows:

[0127] The silicon nano-inorganic flame-retardant and thermal insulation coating of this embodiment is prepared from the following raw materials:

[0128] 500g silicone-acrylic emulsion, 100g pretreated silicone-based nano-aerogel, 100g pretreated titanium dioxide, 40g dodecyl alcohol ester, 10g composite additive, 10g propylene glycol, 2g cellulose, 4g defoamer, 3g thickener, 1g neutralizer, 8g silanized flexible organic fiber, 2g organically modified layered reinforcing material, 255g deionized water;

[0129] The preparation method of organically modified layered reinforced materials includes the following steps:

[0130] S31: Add 0.5g of hexadecyltrimethylammonium bromide to 10g of deionized water and stir at 200rpm for 5min to obtain a homogeneous organic ammonium solution.

[0131] S32: Add 5g of sodium montmorillonite to 100g of deionized water, ultrasonically disperse for 20min at 200W power and 20kHz frequency, heat to 75℃, slowly add organic ammonium solution, stir and mix at 200rpm for 4h after addition, cool to room temperature, centrifuge, wash twice with deionized water and once with anhydrous ethanol, and vacuum dry at 80℃ to constant weight to obtain organically modified layered reinforced material.

[0132] Among them, sodium-based montmorillonite has a particle size of 1~5μm and a specific surface area of ​​20~40m². 2 / g;

[0133] The preparation method of the silicon nano-inorganic flame-retardant and heat-insulating coating in this embodiment includes the following steps:

[0134] Add 80% of the mass of deionized water to a mixing tank, start stirring, and adjust the speed to 300 rpm. Then slowly add cellulose and propylene glycol, and stir for 20 minutes. Continue stirring at 300 rpm, add composite additives, and stir for 15 minutes. Add 50% of the mass of silanized flexible organic fiber, organically modified layered reinforcing material, pretreated titanium dioxide, pretreated silicon-based nano aerogel, and defoamer, adjust the speed to 800 rpm, and stir for 30 minutes. Adjust the speed to 300 rpm, slowly add silicone-acrylic emulsion, and stir for 15 minutes. Add dodecyl alcohol ester, and stir for 10 minutes. Slowly add thickener adjusted to a paste state with deionized water and the remaining deionized water, and stir for 15 minutes. Add neutralizer and the remaining defoamer, adjust the speed to 200 rpm, and stir for 10 minutes to obtain silicon nano inorganic flame-retardant thermal insulation coating.

[0135] The rest is the same as in Example 5.

[0136] Example 7

[0137] The difference between this embodiment and embodiment 6 is that:

[0138] The silicon nano-inorganic flame-retardant and thermal insulation coating of this embodiment is prepared from the following raw materials:

[0139] 500g silicone-acrylic emulsion, 100g pretreated silicone-based nano-aerogel, 100g pretreated titanium dioxide, 40g dodecyl alcohol ester, 10g composite additive, 10g propylene glycol, 2g cellulose, 4g defoamer, 3g thickener, 1g neutralizer, 8g silanized flexible organic fiber, 4g organically modified layered reinforcing material, 257g deionized water;

[0140] The preparation method of organically modified layered reinforced materials includes the following steps:

[0141] S31: Add 1g of hexadecyltrimethylammonium bromide to 10g of deionized water and stir at 200rpm for 5min to obtain a homogeneous organic ammonium solution.

[0142] S32: Add 5g of mica sheets to 100g of deionized water, ultrasonically disperse for 20min at 200W power and 20kHz frequency, heat to 85℃, slowly add organic ammonium solution, stir and mix at 200rpm for 3h after addition, cool to room temperature, centrifuge, wash twice with deionized water and once with anhydrous ethanol, and vacuum dry at 80℃ to constant weight to obtain organically modified layered reinforced material.

[0143] The mica flakes have a particle size of 2-8 μm and a specific surface area of ​​10-20 m². 2 / g;

[0144] The rest is the same as in Example 6.

[0145] Comparative Example 1

[0146] The difference between this comparative example and Example 1 is as follows:

[0147] The preparation method of the pretreated silicon-based nano-aerogel in this example includes the following steps:

[0148] S11: Add 15g of methyltrimethoxysilane and 25g of isobutyltriethoxysilane to 1700g of ethanol aqueous solution, mix well, adjust the pH to 5.0 with 8% acetic acid by mass, heat to 50℃, and pre-hydrolyze at a constant temperature for 4h to obtain pre-hydrolyzed solution.

[0149] S12: Immerse 500g of silica nano-aerogel in a pre-hydrolyzed solution, stir and mix at 200rpm for 15min, seal and evacuate to -0.1MPa, maintain for 70min; slowly restore to normal pressure (1 standard atmosphere), heat to 50℃, immerse for 6h, filter, vacuum dry at 60℃ for 8h, then perform gradient temperature curing, first heat to 80℃, hold for 5h, then heat to 155℃, hold for 6h, cool to room temperature, wash 3 times with anhydrous ethanol, vacuum dry at 80℃ to constant weight, to obtain pretreated silica-based nano-aerogel.

[0150] Everything else is the same as in Example 1.

[0151] Comparative Example 2

[0152] The difference between this comparative example and Example 1 is as follows:

[0153] The preparation method of the pretreated titanium dioxide in this comparative example includes the following steps:

[0154] S21: Add 500g of titanium dioxide to 2500g of ethanol aqueous solution, ultrasonically disperse for 30min at 200W and 20kHz, add 60g of vinyltrimethoxysilane, stir and mix at 200rpm for 10min, adjust the pH to 5.0 with 8% acetic acid, heat to 50℃, react for 6h, cool to room temperature, centrifuge, wash 3 times with deionized water, and vacuum dry at 80℃ for 12h to obtain silanized titanium dioxide;

[0155] S22: Under a nitrogen atmosphere, silanized titanium dioxide was added to 1500 mL of mixed solvent and ultrasonically dispersed for 20 min at a power of 200 W and a frequency of 20 kHz. Then, 15 g of 2-methyl-2-acrylate-2-hydroxyethyl ester phosphate and 15 g of pentabromobenzyl acrylate were added and stirred at 200 rpm until homogeneous. The mixture was then heated to 70 °C and azobisisobutyronitrile solution (0.8 g of azobisisobutyronitrile mixed with 10 mL of isopropanol) was slowly added dropwise. The mixture was reacted for 10 h, cooled to room temperature, centrifuged, washed three times with anhydrous ethanol, and vacuum dried at 80 °C to constant weight to obtain pretreated titanium dioxide.

[0156] Everything else is the same as in Example 1.

[0157] Comparative Example 3

[0158] The difference between this comparative example and Example 1 is as follows:

[0159] Silanized titanium dioxide was used to replace pretreated titanium dioxide of equal quality.

[0160] The preparation method of the silanized titanium dioxide in this comparative example includes the following steps:

[0161] Add 500g of titanium dioxide to 2500g of ethanol aqueous solution, ultrasonically disperse for 30min at 200W and 20kHz, add 60g of vinyltrimethoxysilane, stir and mix at 200rpm for 10min, adjust the pH to 5.0 with 8% acetic acid, heat to 50℃, react for 6h, cool to room temperature, centrifuge, wash three times with deionized water, and vacuum dry at 80℃ for 12h to obtain silanized titanium dioxide.

[0162] Everything else is the same as in Example 1.

[0163] Performance testing

[0164] The silicon nano-inorganic flame-retardant thermal insulation coatings prepared in Examples 1-7 and Comparative Examples 1-3 were tested according to GB / T9756-2018 "Synthetic Resin Emulsion Interior Wall Coatings", GB / T10294-2008 "Determination of Steady-State Thermal Resistance and Related Characteristics of Thermal Insulation Materials - Protective Hot Plate Method", GB18582-2020 "Limits of Hazardous Substances in Wall Coatings for Buildings", and GB8624-2012 "Classification of Combustion Performance of Building Materials and Products". The specific results are shown in Table 1.

[0165] Table 1. Performance test results of silicon nano-inorganic flame-retardant and thermal insulation coatings prepared in Examples 1-7 and Comparative Examples 1-3

[0166]

[0167] The environmental indicator "not detected" means that the VOC content, total lead content, formaldehyde content, and soluble heavy metal (cadmium, chromium, mercury) content all meet the limits specified in GB 18582-2020 "Limits of Hazardous Substances in Wall Coatings for Buildings". Furthermore, in terms of application, the coating forms a film without abnormalities at 5°C, two coats can be applied without difficulty, and the surface drying time is approximately 1 hour.

[0168] Analysis of test results:

[0169] Analysis of Examples 1 and Comparative Examples 1-3 shows that by pretreating silica nano-aerogels with dihydroxy polydimethylsiloxane, methyltrimethoxysilane, and isobutyltriethoxysilane, a cross-linked network can be formed inside and on the surface of the aerogel, improving the overall flame retardant performance. Titanium dioxide without polyether segment modification, due to decreased interfacial compatibility with the silicone-acrylic emulsion matrix and a slight increase in interfacial defects, directly leads to a slight increase in thermal conductivity. Titanium dioxide treated only with single silanization lacks both the synergistic flame retardant effect of flame-retardant groups and the interfacial adaptation function of polyether segments. This results in slightly uneven dispersion of titanium dioxide in the matrix, increased interfacial gaps, and smoother heat conduction paths, leading not only to a significant increase in thermal conductivity but also a slight decrease in flame retardant performance and a reduction in washability.

[0170] Analysis of Examples 1-7 shows that a composite system with strong interfacial bonding was successfully constructed based on pretreated silica nano-aerogel and pretreated titanium dioxide, enabling the coating to possess both excellent thermal insulation and flame retardancy. Under this premise, the interfacial bonding between components and the integrity of the coating structure were optimized by introducing silanized flexible organic fibers, making the thermal insulation performance more stable. Subsequently, organically modified sheet reinforcement materials were superimposed to construct a multi-layer physical barrier network, further optimizing the flame retardancy and thermal insulation performance.

[0171] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A silicon nano-inorganic flame-retardant and thermal insulation coating, characterized in that, It is prepared from the following raw materials in parts by weight: The composition includes: 450-550 parts silicone-acrylic emulsion, 90-110 parts pretreated silicone-based nano-aerogel, 90-110 parts pretreated titanium dioxide, 38-42 parts film-forming aid, 7-12 parts composite aid, 9-11 parts diols, 1.5-2.5 parts cellulose, 3-5 parts defoamer, 2-4 parts thickener, 0.8-1.2 parts neutralizer, and 225-260 parts water. The pretreated silicon-based nano-aerogel was prepared by the following method: after vacuum-assisted impregnation with a pre-hydrolyzed solution of dihydroxy polydimethylsiloxane, short alkyl chain silane and long alkyl chain silane, it was then subjected to gradient temperature curing treatment. The pretreated titanium dioxide is prepared by the following method: first, it is silanized on the surface by a silane coupling agent containing double bonds, and then it is surface copolymerized and grafted with a vinyl-containing phosphorus compound, a vinyl-containing bromine compound and a vinyl-containing polyether monomer.

2. The silicon nano-inorganic flame-retardant and thermal insulation coating according to claim 1, characterized in that, Compound additives include bactericides, antifungal and antialgae agents, preservatives, dispersants, and wetting agents.

3. The silicon nano-inorganic flame-retardant and thermal insulation coating according to claim 1, characterized in that, The preparation method of the pretreated silicon-based nano-aerogel includes the following steps: S11: Add dihydroxy polydimethylsiloxane, short-chain silane and long-chain silane to an aqueous ethanol solution, mix well, adjust the pH to 4.0~5.0, heat to 50~70℃, and pre-hydrolyze for 2~4 hours to obtain a pre-hydrolyzed solution; S12: The silicon-based nano-aerogel is immersed in a pre-hydrolyzed solution and kept at -0.1 to -0.08 MPa for 50 to 70 min. After restoring to normal pressure, the temperature is raised to 50 to 70 °C and immersed for 4 to 6 h. After solid-liquid separation and drying, the temperature is gradually increased to solidify the aerogel. The temperature range is 80 to 165 °C and the time is 7 to 11 h. After cooling, the aerogel is washed and dried to obtain the pretreated silicon-based nano-aerogel.

4. The silicon nano-inorganic flame-retardant and thermal insulation coating according to claim 3, characterized in that, The specific steps of the gradient temperature curing are as follows: first, raise the temperature to 80~90℃ and keep it at that temperature for 3~5 hours, then continue to raise the temperature to 155~165℃ and keep it at that temperature for 4~6 hours.

5. The silicon nano-inorganic flame-retardant and thermal insulation coating according to claim 1, characterized in that, The mass ratio of the dihydroxy polydimethylsiloxane, short alkyl chain silane, long alkyl chain silane and silicon-based nanoaerogel is (10~20):(3~7):(5~15):

100.

6. The silicon nano-inorganic flame-retardant and thermal insulation coating according to claim 1, characterized in that, The method for preparing the pretreated titanium dioxide includes the following steps: S21: Disperse titanium dioxide in an aqueous ethanol solution, add a silane coupling agent containing double bonds, adjust the pH to 4.0~5.0, heat to 50~70℃, react for 4~6h, cool, separate the solid and liquid, wash, and dry to obtain silanized titanium dioxide. S22: Under an inert atmosphere, silanized titanium dioxide is dispersed in a mixed solvent, and a vinyl-containing phosphorus compound, a vinyl-containing bromine compound, and a vinyl-containing polyether monomer are added and mixed evenly. The mixture is heated to 70-80°C, an initiator is added, and the reaction is carried out for 6-10 hours. After cooling, washing, and drying, pretreated titanium dioxide is obtained.

7. The silicon nano-inorganic flame-retardant and thermal insulation coating according to claim 1, characterized in that, The mass ratio of the double-bonded silane coupling agent, the vinyl-containing phosphorus compound, the vinyl-containing bromine compound, the vinyl-containing polyether monomer, and the titanium dioxide is (12~15):(3~5):(3~5):(2~4):

100.

8. The silicon nano-inorganic flame-retardant and thermal insulation coating according to claim 1, characterized in that, The silicon nano-inorganic flame-retardant and thermal insulation coating also includes 5-8 parts by weight of silanized flexible organic fibers.

9. A method for preparing a silicon nano-inorganic flame-retardant and thermally insulating coating as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Cellulose, diols, composite additives and some water are mixed evenly, pretreated titanium dioxide, pretreated silicon-based nano aerogel and some defoamer are added and mixed evenly, silicone acrylic emulsion and film-forming aid are added and mixed evenly, thickener, remaining water, neutralizer and remaining defoamer are added and mixed evenly to obtain silicon nano inorganic flame retardant and heat insulation coating.

10. The preparation method of the silicon nano-inorganic flame-retardant and heat-insulating coating according to claim 9, characterized in that, The process also includes adding silanized flexible organic fibers before adding pretreated titanium dioxide.

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