External wall heat insulation coating and preparation method thereof

Abstract

The invention discloses an external wall heat insulation coating and a preparation method thereof, belongs to the technical field of building coatings, and aims to solve the problems of poor filler dispersity, insufficient heat insulation and reflection synergy and poor weather resistance and adhesive force of the conventional external wall heat insulation coating. The coating is prepared from the following raw materials in parts by weight: 8 to 15 parts of modified aerogel-hollow glass bead composite filler, 5 to 12 parts of modified titanium dioxide, 20 to 30 parts of organic-inorganic hybrid adhesive, 1 to 3 parts of dispersing agent, 2 to 5 parts of coalescing agent and 30 to 45 parts of deionized water, the preparation method comprises the following steps: dispersing the dispersing agent into the deionized water, mixing with the modified aerogel-hollow glass bead composite filler to obtain slurry, mixing the modified titanium dioxide, the organic-inorganic hybrid adhesive and the slurry, cooling, and mixing with the film forming agent. The coating prepared by the invention is mainly used for heat insulation engineering of building exterior walls.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building coatings. More particularly, the present application relates to a kind of external wall thermal insulation coating and a preparation method thereof. BACKGROUND

[0002] As a commonly used material in the field of building energy saving, the core function of external wall thermal insulation coating is to block the heat transfer of solar radiation and the heat exchange between indoor and outdoor, so as to reduce the building energy consumption. In the prior art, this kind of coating is usually prepared by selecting aerogel, hollow glass microspheres and the like as thermal insulation functional fillers, titanium dioxide and the like as reflective functional fillers, and matching corresponding binders, dispersants and the like additives. However, there are still some problems to be solved in practical application.

[0003] Firstly, the dispersion stability of functional fillers is poor. Aerogel itself has hydrophobic properties and poor compatibility with water-based coating binder, and is prone to agglomeration in the coating system. If hollow glass microspheres and titanium dioxide and the like fillers are not subjected to targeted treatment, they are also prone to uneven dispersion. These problems will cause the coating to separate and precipitate during storage, and the internal structure of the coating after construction is uneven, which will cause the thermal insulation performance to fluctuate greatly and cannot guarantee the stability of the use effect. This is because the surface properties of the fillers and the compatibility of the binder are not good enough, and simply relying on the addition of dispersants cannot fundamentally improve the agglomeration problem of the fillers. How to improve the dispersion and compatibility of different types of fillers in the water-based system without affecting other properties of the coating is a big difficulty in the prior art.

[0004] Secondly, the synergy of thermal insulation and reflection is insufficient. The existing coating mostly uses a single type of thermal insulation filler or reflective filler, or simply physically mixes different fillers without formulating design for the synergistic effect of the two functions. This makes the coating often only focus on one of the functions of thermal insulation or reflection, and it is difficult to achieve the effect of efficient thermal insulation and efficient reflection of solar radiation at the same time. The core reason is that the functional characteristics of thermal insulation fillers and reflective fillers are different, and simple collocation is prone to insufficient functional superposition or mutual influence. How to make two different functional fillers cooperate and synergize in the coating system is a problem that has not been properly solved for a long time.

[0005] Finally, the weather resistance and adhesion of the coating need to be improved. The binders used in existing coatings are mostly single organic or inorganic types. Single organic binders have poor weather resistance and are prone to aging and decomposition when exposed to the outdoors for a long time. Single inorganic binders lack flexibility. At the same time, the weather resistance of ordinary titanium dioxide and other reflective fillers is limited. These factors together cause the coating to age, become hollow, and fall off in complex outdoor environments, affecting the service life of the coating. This is because the performance of single binders cannot balance adhesion and weather resistance, and the bonding force between fillers and binders is insufficient. How to optimize the compatibility of the binder system and the filler, while improving the weather resistance of the filler itself, to enhance the overall durability of the coating, is a difficult problem to balance in existing technology. SUMMARY

[0006] The purpose of the present application is to provide an external wall thermal insulation coating and a preparation method thereof, to at least solve the following problems: Existing external wall thermal insulation coatings generally have weak thermal insulation performance, poor compatibility of fillers and coating systems, and the problem of uneven dispersion of traditional fillers, which further leads to poor coating stability and easy decay of thermal insulation effect; Conventional titanium dioxide is prone to agglomeration in coatings, has limited hiding power and weather resistance, and has poor compatibility with other components, which leads to poor optical performance and short service life of the coating, making it difficult to meet the long-term use requirements of external walls; Existing binders have the defects of poor water resistance of single organic phase and poor toughness of single inorganic phase, and unreasonable solid content, which leads to insufficient adhesion and poor film-forming property of the coating, affecting the construction effect and service life of the coating; Traditional dispersants have limited dispersion effect on inorganic fillers (such as composite fillers and titanium dioxide) in coatings, which easily leads to filler agglomeration, affecting the storage stability, construction smoothness and coating uniformity of the coating, and ultimately reducing the thermal insulation effect; Existing film-forming aids often have low film-forming efficiency and improper evaporation speed, which easily leads to incomplete film formation and cracking of the coating. Some aids may also leave harmful substances, affecting the environmental friendliness and durability of the coating; In the preparation of existing external wall thermal insulation coatings, there are problems such as unreasonable feeding sequence, improper stirring speed or time control, uncontrollable heating rate, and no defoaming process, which leads to uneven mixing of components, incomplete reaction, coating containing bubbles, and the problem of large performance fluctuations and poor uniformity of the finished coating; In the preparation of existing modified aerogel-hollow glass microsphere composite fillers, the aerogel is easily oxidized and not fully modified during crushing, the impurities of hollow glass microspheres are not completely removed, and the compatibility of the two is poor, which leads to insufficient function of the filler and affects the thermal insulation effect of the coating; The existing coating is directly packaged after filtration, and is prone to stratification and precipitation during storage due to insufficient stability of components, thereby affecting the uniformity and performance of the coating during subsequent construction and affecting the heat insulation effect of the coating.

[0007] In order to achieve the purpose and other advantages of the present application, an external wall heat insulation coating is provided, and raw materials include, by weight: modified aerogel-hollow glass microsphere composite filler 8-15 parts, modified titanium white 5-12 parts, organic-inorganic hybrid binder 20-30 parts, dispersant 1-3 parts, film forming aid 2-5 parts, and deionized water 30-45 parts; wherein the modified aerogel-hollow glass microsphere composite filler is made by mixing aerogel modified by a silane coupling agent and hollow glass microspheres pretreated at a high temperature of 400-600 DEG C at a weight ratio of 1:2; the silane coupling agent is one or a mixture of both of KH-550 and KH-560; Preferably, the modified titanium white is ZrO2-Al2O3-organic silicon triple modified titanium white.

[0008] Preferably, the organic-inorganic hybrid binder is an acrylate-silica sol hybrid binder, and the solid content of the acrylate-silica sol hybrid binder is 35-45%.

[0009] Preferably, the dispersant is a polycarboxylate dispersant.

[0010] Preferably, the film forming aid is propylene glycol methyl ether acetate or alcohol ester twelve.

[0011] The present application also provides a preparation method of the above-mentioned external wall heat insulation coating, comprising: step one, adding a dispersant in deionized water, and adding a modified aerogel-hollow glass microsphere composite filler under low-speed stirring at 300-500 rpm, dispersing at a linear speed of 10-15 m / s for 5-10 minutes, and then increasing the linear speed to 18-20 m / s for 10-15 minutes to obtain a stable slurry; step two, mixing modified titanium white and an organic-inorganic hybrid binder, heating to 45-50 DEG C at a heating rate of 2-3 DEG C / min and maintaining the temperature for stirring, then slowly adding the slurry obtained in step one under nitrogen protection, maintaining the temperature for continuous stirring, and then performing vacuum degassing treatment at a vacuum degree of -0.08 to -0.095 MPa for 10-20 minutes; step three, cooling to room temperature, adding a film forming aid, adjusting the coating viscosity to 50-80 seconds after low-speed stirring, and filtering with a 100-120 mesh filter screen to obtain the coating.

[0012] Preferably, in step one, the preparation method of the modified aerogel-hollow glass microsphere composite filler comprises the following steps: S1, mechanically crushing the bulk aerogel under the protection of inert gas, and passing through a 400-600 mesh sieve to obtain aerogel powder; S2, dispersing the aerogel powder in anhydrous ethanol, adding silane coupling agent KH-550 or KH-560, and performing high-speed shearing dispersion reaction at 80-90°C and a rotation speed of 1000-12000 rpm for 2-3 hours; after the reaction is completed, centrifugation and drying are performed to obtain hydrophobically modified aerogel; S3, calcining the hollow glass microspheres at 500-600°C for 1-2 hours and naturally cooling to room temperature; S4, putting the hydrophobically modified aerogel obtained in step S2 and the pretreated hollow glass microspheres obtained in step S3 into a high-speed mixer at a weight ratio of 1:2, spraying 0.5%-1% of silicone oil based on the total weight of the composite filler, and mixing at 50-60°C and a rotation speed of 300-600 rpm for 20-30 minutes to obtain the modified aerogel-hollow glass microsphere composite filler.

[0013] Preferably, it further comprises: step four, continuously and slowly stirring the filtered paint at 25-35°C for at least 24 hours, and then packaging.

[0014] The present application at least includes the following beneficial effects: First, by using specific weight ratios of raw materials and modified composite fillers, the thermal insulation performance of the exterior wall coating can be significantly improved. The aerogel modified by the silane coupling agent itself has excellent thermal insulation capacity, and the hollow glass microspheres pretreated at 400-600°C can remove impurities and enhance structural stability. Mixing them at a ratio of 1:2 can form a synergistic thermal insulation effect, which not only retains the low thermal conductivity of aerogel, but also enhances the mechanical properties of the filler with the help of hollow glass microspheres. At the same time, the silane coupling agent can also improve the compatibility of the composite filler with the organic-inorganic hybrid binder, reduce filler agglomeration, make the coating system more stable, and form a coating with good uniformity after construction, which can maintain the thermal insulation effect of the exterior wall for a long time, and is suitable for complex use environment of exterior wall, and is not easy to cause performance degradation due to external factors.

[0015] Second, using ZrO2-Al2O3-silicone triple modified titanium dioxide can effectively compensate for the defects of traditional titanium dioxide. ZrO2 and Al2O3 can enhance the chemical stability and weather resistance of titanium dioxide, so that it is not easy to degrade in outdoor environments such as ultraviolet radiation and rainwater erosion, prolonging the service life of the coating; silicone modification can improve the compatibility of titanium dioxide with the organic-inorganic hybrid binder in the coating, avoid titanium dioxide agglomeration, make it uniformly dispersed in the coating, and thus enhance the hiding power of the coating, which can effectively hide the base color of the exterior wall substrate and reduce the problem of coating penetration. In addition, the modified titanium dioxide can also work synergistically with the composite filler to improve the appearance flatness and color stability of the coating while ensuring the thermal insulation performance, thereby reducing the frequency of later renovation of the exterior wall.

[0016] Third, select the acrylate-silica sol hybrid binder and limit the solid content of 35-45%, which can take into account the flexibility and weather resistance of the coating. The acrylate component can provide good flexibility for the binder, allowing the coating to slightly stretch with the exterior wall substrate when the temperature changes, reducing the risk of cracking and falling off; the silica sol component can improve the water resistance and alkali resistance of the binder, adapt to the use scenario of the exterior wall which is easy to contact with rainwater and alkaline substrate, and avoid the failure of the binder due to water absorption or corrosion by alkali. The solid content of 35-45% can ensure that the binder can fully form a film to form a dense coating structure to prevent external moisture and dust from penetrating, and also can not cause the coating to be too thick due to high solid content, affecting the leveling property of the coating, while enhancing the adhesion of the coating to the exterior wall substrate and improving the overall structural stability of the coating.

[0017] Fourth, specify the polycarboxylate dispersant to significantly optimize the dispersion effect of the coating system. The polycarboxylate dispersant has good adsorption and steric hindrance effect, which can firmly adsorb on the surface of modified aerogel-hollow glass microsphere composite filler, modified titanium dioxide and other solid particles to form a stable dispersion layer, effectively preventing particle aggregation, allowing each component to be uniformly dispersed in deionized water to form a stable slurry. This not only avoids the problem of stratification and precipitation of the coating during storage, prolonging the shelf life of the coating, but also improves the leveling property of the coating during construction, ensuring uniform coating thickness and preventing differences in thermal insulation performance caused by uneven local filler concentration. At the same time, good dispersion effect can also reduce the stirring energy consumption during preparation, improving the production efficiency of the coating.

[0018] Fifth, select propylene glycol methyl ether acetate or alcohol ester twelve as a film-forming aid to ensure the film-forming quality of the coating and consider environmental protection. These two film-forming aids have moderate volatility and can be slowly released during the film-forming process of the coating, effectively reducing the film-forming temperature of the organic-inorganic hybrid binder, allowing the binder to fully crosslink at room temperature or lower temperature to form a continuous and dense coating structure, avoiding defects such as cracks and shrinkage due to incomplete film formation, improving the sealing property of the coating, and reducing the penetration of harmful substances from the outside. In addition, both have good environmental performance and no harmful residues after film formation, which not only meets the environmental protection standards of exterior wall coatings, ensuring the health of construction personnel and the safety of the surrounding environment, but also further enhances the weather resistance and service life of the coating through a complete film structure.

[0019] Sixth, the coating preparation method can ensure the uniformity and stability of the performance of the finished product by precisely controlling the parameters of each step. In step one, low-speed stirring of 300-500 rpm when adding fillers can avoid dust flying, and subsequent gradient improvement of the linear speed of dispersion can prevent the agglomeration of fillers and ensure the stability of the slurry. In step two, the controlled temperature rise of 2-3 ℃ / min can avoid uneven reaction of modified titanium dioxide and binder caused by sudden temperature rise, nitrogen protection can prevent oxidation of components, and vacuum degassing can remove bubbles in the coating to avoid pores in the coating layer affecting thermal insulation and appearance. Step three adjusts the viscosity to 50-80 seconds and uses a 100-120 mesh filter to remove impurity particles, which can ensure the adaptability of the coating during construction and ultimately make the coating layer formed after construction have high quality, consistent thermal insulation effect, and no local performance defects.

[0020] Seventh, the composite filler preparation method can fully exert the synergistic effect of aerogel and hollow glass microbeads. In step S1, the aerogel is crushed under inert gas protection and passed through a 400-600 mesh screen to prevent oxidation of the aerogel and damage to its porous thermal insulation structure, and to control the uniformity of the powder particle size for subsequent modification; the modification of the silane coupling agent in step S2 can make the aerogel hydrophobic and improve its compatibility with other components; in step S3, the hollow glass microbeads are calcined at 500-600 ℃ to remove impurities on the surface of the microbeads and enhance their mechanical strength; in step S4, the silicon oil is used to assist mixing and control the temperature and speed to promote the close combination of the hydrophobic aerogel and the pretreated microbeads and prevent separation of the two. The finally prepared composite filler has good dispersibility and stable structure, can continuously exert excellent thermal insulation performance after being added to the coating, and can also enhance the impact resistance of the coating layer and reduce the problem of coating peeling caused by the fragility of the filler.

[0021] Eighth, slow stirring for at least 24 hours in a 25-35 ℃ environment after filtration and then packaging can further improve the storage stability and construction consistency of the coating. The filtered coating may have local component concentration unevenness, and a mild environment of 25-35 ℃ can avoid temperature that is too high or too low affecting the stability of the components, and slow stirring can allow the components in the coating to fully blend, prevent solid particles from settling due to gravity, and avoid stratification and precipitation during storage. This can ensure the stability of the coating during subsequent transportation and storage, eliminate the need for additional repeated stirring during construction, ensure the uniformity of the coating taken each time, prevent local thermal insulation and insufficient hiding power of the coating layer formed after construction, and extend the storage shelf life of the coating, reducing material loss and the risk of construction rework caused by deterioration of the coating.

[0022] Other advantages, objects, and features of the present application will be apparent from the following description, and will be understood by those skilled in the art. DETAILED DESCRIPTION

[0023] The application will be further described in detail below with reference to the examples, so that those skilled in the art can implement the application according to the description.

[0024] It should be noted that the experimental methods described in the following examples are all conventional methods unless otherwise specified, and the reagents and materials can be obtained commercially unless otherwise specified.

[0025] Experimental materials and equipment 1. Main raw materials: block-shaped silica aerogel (purity 99.5%), hollow glass microbeads (particle size 50-80 μm), silane coupling agent KH-550 / KH-560 (analytical pure), titanium white (anatase type, particle size 200-300 mesh), ZrO2sol (solid content 20%), Al2O3sol (solid content 20%), acrylate emulsion (solid content 50%), silica sol (solid content 30%), polycarboxylic acid sodium salt dispersant (solid content 30%), propylene glycol methyl ether acetate (analytical pure), dimethyl silicone oil (viscosity 50 cSt), deionized water (conductivity ≤10 μS / cm); conventional comparative raw materials: unmodified titanium white, single acrylate binder (solid content 40%), sodium dodecyl benzene sulfonate, ethylene glycol ethyl ether acetate.

[0026] 2. Main equipment: planetary ball mill, high-speed shear reaction kettle, high-speed centrifuge, vacuum drying oven, muffle furnace, high-speed mixer, constant-temperature stirring tank, protective hot plate heat conduction instrument, ultraviolet-visible-near infrared spectrophotometer, color difference meter, grid knife, metallographic microscope, Brookfield-4 cup viscometer, xenon lamp aging test box.

[0027] Example 1 A preparation method of an external wall thermal insulation coating, comprising: Step one (raw material formula), according to the design formula, accurately weigh 12 parts of modified aerogel-hollow glass microbead composite filler, 8 parts of ZrO2-Al2O3-organic silicon triple modified titanium white, 25 parts of acrylate-silica sol hybrid binder, 2 parts of polycarboxylic acid salt dispersant, 3 parts of propylene glycol methyl ether acetate and 38 parts of deionized water.

[0028] The preparation method of the modified aerogel-hollow glass microsphere composite filler includes: S1, pulverizing block silica aerogel under nitrogen protection using a planetary ball mill (800 rpm, 30 min) and passing it through a 500-mesh sieve to obtain aerogel powder; S2, dispersing the aerogel powder in anhydrous ethanol at a solid-liquid ratio of 1:10, adding 5% KH-560 by weight of the powder, reacting at 85℃ and 1100 rpm at high speed for 3 h, centrifuging at 3000 rpm for 15 min, and vacuum drying at 80℃ for 4 h to obtain hydrophobic modified aerogel; S3, calcining hollow glass microspheres at 5℃ / min to 550℃ for 1.5 h, and then naturally cooling; S4, mixing the hydrophobic aerogel and pretreated hollow glass microspheres at a weight ratio of 1:2, spraying with 0.8% dimethyl silicone oil by weight of the total composite filler, and mixing at 55℃ and 450 rpm for 25 min to obtain the final product.

[0029] The preparation method of ZrO2-Al2O3-organosilicon triple-modified titanium dioxide includes: dispersing titanium dioxide in deionized water, adding ZrO2 sol and Al2O3 sol (both with a solid content of 20%), stirring at 60℃ for 2 hours; adding 3% KH-550, stirring at 70℃ for 1 hour, filtering and drying, and then calcining at 300℃ for 1 hour to obtain the product.

[0030] The preparation method of acrylate-silica sol hybrid binder includes: mixing acrylate emulsion (50% solid content) and silica sol (30% solid content) at a weight ratio of 6:4, adding 0.5% KH-560, stirring at 40℃ for 1 hour, and adjusting the solid content to 40% to obtain the binder.

[0031] Step 2 (Slurry Preparation): Add 2 parts of dispersant to 38 parts of deionized water and stir at 300 rpm for 5 min; add 12 parts of composite filler in 3 portions, first disperse at 12 m / s for 8 min, then disperse at 19 m / s for 12 min to obtain a stable slurry.

[0032] Step 3 (Mixing and Degassing): Add 8 parts of modified titanium dioxide to 25 parts of hybrid binder, stir at 800 rpm for 5 min, heat to 48℃ at 2.5℃ / min and hold for 30 min; purge with nitrogen, pump in the slurry obtained in Step 2 (50 mL / min), maintain at 48℃ and stir for 20 min; then degas under vacuum at -0.09 MPa for 15 min (stirring at 200 rpm for 15 s every 5 min). Step 4 (Volume Adjustment and Filtration): Cool to room temperature, add 3 parts of film-forming aid, stir at 500 rpm for 15 minutes; adjust viscosity to 65 seconds using a Forbes-4 cup, and filter through a 110-mesh filter (0.1 MPa).

[0033] Step 5 (post-stirring and packaging): Stir the filtered slurry at 200 rpm for 24 hours, then seal and package (20 kg / barrel).

[0034] Comparative Example 1: A preparation method of an external wall thermal insulation coating, the general steps are the same as those of Example 1, except that the composite filler is prepared without nitrogen protection (aerogel air crushing), without silane modification, without calcination of microbeads, and without silicon oil mixing. Specifically, the preparation method of the composite filler is as follows: S1, the block-shaped silica aerogel is directly crushed with a planetary ball mill (800 rpm, 30 min), and the aerogel powder is obtained by passing through a 500-mesh sieve; S2, the aerogel powder and hollow glass microbeads are mixed at a weight ratio of 1:2 at 25°C and 450 rpm for 25 min, and the mixture is obtained.

[0035] Comparative Example 2: A preparation method of an external wall thermal insulation coating, the general steps are the same as those of Example 1, except that the composite filler is prepared without nitrogen protection (aerogel air crushing), without silane modification, without calcination of microbeads, and without silicon oil mixing. Specifically, the preparation method of the composite filler is as follows: S1, the block-shaped silica aerogel is directly crushed with a planetary ball mill (800 rpm, 30 min), and the aerogel powder is obtained by passing through a 500-mesh sieve; S2, the aerogel powder and hollow glass microbeads are mixed at a weight ratio of 1:2 at 25°C and 450 rpm for 25 min, and the mixture is obtained.

[0036] Comparative Example 3: A preparation method of an external wall thermal insulation coating, the general steps are the same as those of Example 1, except that the composite filler is prepared without nitrogen protection (aerogel air crushing), without silane modification, without calcination of microbeads, and without silicon oil mixing. Specifically, the preparation method of the composite filler is as follows: S1, the block-shaped silica aerogel is directly crushed with a planetary ball mill (800 rpm, 30 min), and the aerogel powder is obtained by passing through a 500-mesh sieve; S2, the aerogel powder and hollow glass microbeads are mixed at a weight ratio of 1:2 at 25°C and 450 rpm for 25 min, and the mixture is obtained.

[0037] Comparative Example 4: A preparation method of an external wall thermal insulation coating, the general steps are the same as those of Example 1, except that the composite filler is prepared without nitrogen protection (aerogel air crushing), without silane modification, without calcination of microbeads, and without silicon oil mixing. Specifically, the preparation method of the composite filler is as follows: S1, the block-shaped silica aerogel is directly crushed with a planetary ball mill (800 rpm, 30 min), and the aerogel powder is obtained by passing through a 500-mesh sieve; S2, the aerogel powder and hollow glass microbeads are mixed at a weight ratio of 1:2 at 25°C and 450 rpm for 25 min, and the mixture is obtained.

[0038] Comparative Example (Prior Art) (1) Raw material formula: ordinary hollow glass microbeads 12 parts (unmodified, uncalcined), unmodified titanium dioxide 8 parts, single acrylate binder 25 parts (40% solid content), sodium dodecyl benzene sulfonate 2 parts, ethylene glycol ether acetate 3 parts, deionized water 38 parts.

[0039] (2) Preparation process: add sodium dodecyl benzene sulfonate to deionized water, stir at 500 rpm for 5 min; add ordinary hollow glass microbeads and unmodified titanium dioxide, disperse at 15 m / s for 20 min; add single acrylate binder and ethylene glycol ether acetate, stir at 800 rpm for 15 min; adjust the viscosity to 65 seconds, filter through a 100-mesh sieve, and package directly (without nitrogen, without defoaming, without post-stirring).

[0040] Experimental Example: The thermal conductivity, solar reflectance, adhesion grade, crack resistance, aging ΔE, and 60-day viscosity change rate of the coatings prepared in the examples, comparative examples, and comparative example were tested, and the specific test methods are as follows: 1. Thermal conductivity: tested in accordance with GB / T 10294-2022 “Determination of Steady-state Thermal Resistance and Related Properties of Thermal Insulation Materials - Guarded Hot Plate Method”, 5 samples in parallel.

[0041] 2. Solar reflectance: tested in accordance with GB / T 25261-2018 “Reflective Insulation Coating for Buildings”, 5 samples in parallel.

[0042] 3. Adhesion grade: tested in accordance with GB / T 9286-2021 “Paints and Varnishes - Crosshatch Test”, 5 samples in parallel. Adhesion grade is 0-5, 0 grade is that the cutting edge is completely smooth, no grid falls off, 5 grade is that the falling area is greater than 65%.

[0043] 4. Anti-cracking property: tested in accordance with JG / T 25-2017 “Test Method for Temperature Variation Resistance of Architectural Coating Layer”, 5 samples in parallel. Visual rating, excellent: no cracks; good: 1-2 fine cracks; poor: ≥3 cracks.

[0044] 5. Aging color difference ΔE: tested in accordance with GB / T 1865-2022 “Paints and Varnishes - Artificial Weathering and Artificial Radiation Exposure”, 5 samples in parallel.

[0045] 6. 60-day viscosity change rate: tested in accordance with GB / T 1723-2023 “Determination of Viscosity of Coatings - Cup-4 Method”, 3 samples in parallel.

[0046] The experimental results are shown in the following table: Note: The same letter in the table indicates no significant difference between groups p>0.05; different letters indicate significant difference between groups p<0.05.

[0047] From the above table, in Example 1, each feature forms a synergistic effect. In terms of thermal insulation performance (thermal conductivity and solar reflectance), the composite filler (nitrogen protection against aerogel oxidation, high-temperature calcination to remove micro-bead impurities, and silicone to promote bonding) constructs a porous thermal insulation structure, and is matched with triple-modified titanium dioxide (ZrO2 / Al2O3 to enhance solar reflection and organic silicon to promote dispersion), so that the thermal conductivity is as low as 0.030 W / (m·K), the solar reflectance is as high as 0.89, and the double-strengthened thermal insulation effect is achieved. In terms of coating stability, the hybrid binder (acrylate to increase flexibility and silica sol to improve adhesion) ensures 0-level adhesion, and the staged dispersion and vacuum degassing reduce air holes, and the anti-cracking property is excellent, thereby avoiding coating peeling and cracking. In terms of weather resistance and storage property, the triple-modified titanium dioxide improves the weather resistance (aging color difference ΔE is as low as 1.1), and the post-mixing makes the components stable (the viscosity change rate is only 3.0%), thereby solving the problem of deterioration during long-term use and storage. In Comparative Example 1, the composite filler is not protected by nitrogen / silane modification / high-temperature calcination / silicone, the aerogel is oxidized, and the micro-bead contains impurities, which leads to an increase of 40% in thermal conductivity and a decrease of 8.9% in solar reflectance. In Comparative Example 2, there is no staged dispersion / nitrogen / deaeration, the titanium dioxide is not uniformly dispersed, and the coating contains air bubbles, which leads to a decrease of the adhesion to level 2. In Comparative Example 3, unmodified titanium dioxide and a single binder are used, which leads to weak reflection ability (solar reflectance 0.72), poor weather resistance (ΔE=3.2), and poor anti-cracking property. In Comparative Example 4, there is no post-mixing, and the viscosity change rate increases to 22.5% due to the sedimentation of components. In the control example, the use of conventional raw materials and simplified mixing process leads to: the thermal conductivity is 76.7% higher than that of Example 1, the solar reflectance is 26.9% lower, the adhesion is only level 3, the aging color difference ΔE is 4.3 times that of Example 1, and the viscosity change rate is more than 10 times, which proves that the scheme of the present application is not a technical superposition, but a breakthrough in the overall performance of the coating through the synergy of the formula and the process.

[0048] In summary, by using modified composite fillers, triple-modified titanium dioxide, and hybrid binders in the formula, and combining with the optimized process of staged dispersion, nitrogen protection, vacuum degassing, and post-mixing, the present application has made significant progress in thermal insulation, stability, weather resistance, and storage performance, and can meet the long-term and efficient thermal insulation and preservation requirements of external walls.

[0049] The number of devices and the scale of processing described herein are used to simplify the description of the present application. The application, modification, and variation of the external wall thermal insulation and preservation coating and the preparation method thereof are obvious to those skilled in the art.

[0050] Although the embodiments of the present application have been disclosed as above, they are not limited to the application and implementation listed in the specification, and can be fully applied to various fields suitable for the present application, and additional modifications can be easily realized by those skilled in the art, therefore the present application is not limited to specific details, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. An exterior wall thermal insulation coating, characterized in that, By weight, the raw materials include: 8-15 parts modified aerogel-hollow glass microsphere composite filler, 5-12 parts modified titanium dioxide, 20-30 parts organic-inorganic hybrid binder, 1-3 parts dispersant, 2-5 parts film-forming aid, and 30-45 parts deionized water; among which... The modified aerogel-hollow glass microsphere composite filler is prepared by mixing aerogel modified with silane coupling agent and hollow glass microspheres pretreated at 400-600℃ at a weight ratio of 1:2; the silane coupling agent is one or a mixture of two of KH-550 and KH-560.

2. The exterior wall thermal insulation coating as described in claim 1, characterized in that, The modified titanium dioxide is a ZrO2-Al2O3-organosilicon triple-modified titanium dioxide.

3. The exterior wall thermal insulation coating as described in claim 1, characterized in that, The organic-inorganic hybrid binder is an acrylate-silica sol hybrid binder, and the solid content of the acrylate-silica sol hybrid binder is 35-45%.

4. The exterior wall thermal insulation coating as described in claim 1, characterized in that, The dispersant is a polycarboxylate dispersant.

5. The exterior wall thermal insulation coating as described in claim 1, characterized in that, The film-forming aid is propylene glycol methyl ether acetate or dodecyl alcohol ester.

6. The method for preparing the exterior wall thermal insulation coating as described in any one of claims 1-5, characterized in that, include: Step 1: Add dispersant to deionized water, and add modified aerogel-hollow glass microsphere composite filler under low-speed stirring at 300-500 rpm. First, disperse at a linear velocity of 10-15 m / s for 5-10 minutes, and then increase to a linear velocity of 18-20 m / s for 10-15 minutes to obtain a stable slurry. Step 2: Mix the modified titanium dioxide with the organic-inorganic hybrid binder, heat it to 45-50℃ at a heating rate of 2-3℃ / min and keep it at the temperature while stirring. Then, slowly add the slurry obtained in Step 1 under nitrogen protection, maintain the temperature and continue stirring. Then, perform vacuum degassing treatment at a vacuum degree of -0.08 to -0.095MPa for 10-20 minutes. Step 3: Cool to room temperature, add film-forming aid, stir at low speed and adjust the viscosity of the coating to 50-80 seconds, then filter with a 100-120 mesh filter to obtain the final product.

7. The method for preparing the exterior wall thermal insulation coating as described in any one of claims 6, characterized in that, Step one, the preparation method of the modified aerogel-hollow glass microsphere composite filler includes the following steps: S1, mechanically pulverizing the block aerogel under inert gas protection and passing it through a 400-600 mesh sieve to obtain aerogel powder; S2, dispersing the aerogel powder in anhydrous ethanol, adding silane coupling agent KH-550 or KH-560, and performing a high-speed shear dispersion reaction at 80-90℃ and 1000-12000 rpm for 2-3 hours, centrifuging and drying after the reaction to obtain hydrophobic modified aerogel; S3, calcining the hollow glass microspheres at 500-600℃ for 1-2 hours and naturally cooling to room temperature; S4, adding the hydrophobic modified aerogel obtained in step S2 and the pretreated hollow glass microspheres obtained in step S3 into a high-speed mixer at a weight ratio of 1:2, while simultaneously spraying 0.5%-1% of silicone oil (based on the total weight of the composite filler), and mixing at 50-60℃ and 300-600 rpm. The modified aerogel-hollow glass microsphere composite filler was obtained by mixing at a speed of rpm for 20-30 minutes.

8. The method for preparing the exterior wall thermal insulation coating as described in any one of claims 6, characterized in that, It also includes: Step 4, continuously and slowly stirring the filtered coating in an environment of 25-35℃ for at least 24 hours before packaging.

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