Wide-temperature-range self-crosslinking core-shell aerogel building insulation floating coating

Abstract

The invention provides a wide-temperature-range self-crosslinking core-shell aerogel building thermal insulation floating coat coating, and relates to the technical field of building coatings, and the wide-temperature-range self-crosslinking core-shell aerogel building thermal insulation floating coat coating comprises 3-15% of flexible organic thermal insulation particles; the inorganic composite aerogel microspheres are core-shell structure particles which take silicon dioxide aerogel as a core and grow an inorganic silicate hard shell on the surface in situ, and the thickness of a shell layer is 1-6 microns; 0.4 to 2.0 percent of an anti-cracking toughening component; 14 to 25 percent of self-crosslinking type elastic emulsion; 1.5%-4.5% of a compound functional additive; 48 to 62 percent of water; the Stormer viscosity of the coating at the temperature of 25 DEG C is 138-165 KU, and the heat conductivity coefficient of a dry film with the thickness of 2.5-4.0 mm after construction is smaller than or equal to 0.040 W / (m.K). The inorganic composite aerogel microspheres of the core-shell structure are innovatively introduced, a dense inorganic silicate hard shell grows on the surface of hydrophobic silicon dioxide aerogel in situ, a soft-core and hard-shell synergistic system is formed, and the hydrophobic silicon dioxide aerogel composite coating is prepared. The defects that the traditional aerogel powder is easy to agglomerate, settle and fly are avoided.

Description

Technical Field

[0001] This invention relates to the field of architectural coatings technology, specifically to a wide-temperature-range self-crosslinking core-shell aerogel architectural insulation intermediate coating. Background Technology

[0002] As building energy efficiency standards evolve towards near-zero energy consumption, green building materials towards multifunctional integration, and construction methods towards efficient coating, higher demands are placed on the performance of building insulation intermediate coatings. Especially in external wall insulation systems, roof insulation layers, and energy-saving renovations of existing buildings, it is necessary to achieve thin-layer high-efficiency insulation, flexibility and crack resistance, and seamless continuous construction. For example, external walls need a thermal conductivity of less than 0.05 W / (m·K) at a thickness of 3–5 mm, roofs need to withstand thermal stress without cracking, and renovation projects require direct spraying to avoid cold bridging at traditional panel joints. Currently, water-based insulation coatings and aerogel composite materials are widely used in the field of building energy conservation.

[0003] However, existing thermal insulation intermediate coating technologies face the following key technical challenges in achieving the above requirements:

[0004] Aerogels have insufficient dispersion stability and thermal insulation efficiency. Traditional aerogel coatings often directly add hydrophobic silica aerogel powder, which is prone to agglomeration and sedimentation, resulting in a local thermal conductivity of more than 0.06 W / (m·K). After 3 months of storage, the delamination rate is as high as 20%. The thickness of the insulation layer after construction needs to be more than 8mm to meet the standard. Moreover, aerogels fly and pollute the environment, limiting the efficient application of thin layers.

[0005] The coating has limited flexibility and weather resistance. Existing coatings rely on a single elastic emulsion or rubber particles. The dry film will develop micro-cracks when bent at -5℃. After aging at 150℃ for 48 hours, the chalking rate exceeds 15%. The tensile bond strength is less than 0.8MPa. It is easy to peel off from the base layer under temperature difference cycling. It is difficult to meet the crack resistance requirements of a wide temperature range (-20℃~80℃), resulting in a shortened life of the exterior wall.

[0006] Therefore, wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coatings are needed to solve the above problems. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coating, which solves the problems mentioned in the background art above.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coating, which is a water-dispersible single-component coating, comprising the following components by weight percentage:

[0009] Flexible organic thermal insulation particles, 3-15%;

[0010] The inorganic composite aerogel microspheres comprise 4-18% of the total content. These inorganic composite aerogel microspheres are core-shell structured particles with silica aerogel as the core and an inorganic silicate hard shell grown in situ on the surface. The shell thickness is 1-6 μm.

[0011] Crack-resistant and toughening components: 0.4–2.0%;

[0012] 14-25% self-crosslinking elastic emulsion;

[0013] Composite functional additives: 1.5–4.5%;

[0014] Water content: 48-62%;

[0015] The coating has a Stormer viscosity of 138–165 KU at 25°C, and the thermal conductivity of a 2.5–4.0 mm thick dry film after application is ≤0.040 W / (m·K). Furthermore, it shows no cracking or powdering after being bent at -10°C and heated in an oven at 150°C for 72 hours.

[0016] Preferably, the inorganic composite aerogel microspheres are prepared by the following steps: dispersing hydrophobic silica aerogel powder in a water-alcohol mixture containing a silane coupling agent and an alkaline catalyst, adding tetraethyl orthosilicate and silica sol mixed precursor dropwise, hydrolyzing and condensing in situ on the surface of the aerogel particles to form a dense inorganic silicate hard shell, and drying to obtain composite aerogel microspheres with intact core-shell structure and no shell detachment, with an average particle size of 20-90 μm and a bulk density of 0.22-0.42 g / cm³.

[0017] Preferably, the flexible organic thermal insulation particles are selected from one or more of closed-cell elastic polyurethane microspheres, thermoplastic polyolefin elastomer foam particles, or recycled rubber micropowder pre-coated with a 2-5% hydrophilic polyvinyl alcohol thin layer, with a particle size of 80-350 μm and a compression set ≥60%, to provide coating stress buffering and flexible deformation capability.

[0018] Preferably, the crack-resistant and toughening component is composed of modified polypropylene fibers with a length of 1.5 to 6 mm and corundum whiskers or sepiolite whiskers with an average aspect ratio of ≥20 in a weight ratio of 1:0.4 to 1:1.5, forming a three-dimensional interlocking network in the coating, so that the dry film tensile bond strength is ≥1.1 MPa and the elongation at break is ≥80%.

[0019] Preferably, the self-crosslinking elastic emulsion is a siloxane-acrylate core-shell emulsion or a waterborne polyurethane-acrylate hybrid emulsion, incorporating a diacetone acrylamide / adipate dihydrazide room temperature self-crosslinking system, with a solid content of 50-56%, a minimum film-forming temperature of ≤5℃, and a crosslinking density after film formation such that the coating's water resistance whitening time is ≥240h.

[0020] Preferably, the composite functional additive comprises:

[0021] 0.8–2.2% of a specialized block polyether dispersant for core-shell aerogel microspheres;

[0022] A thickening system of 0.5-1.8% of an associative hydrophobic modified alkali-swellable thickener and a polyurethane rheology modifier gives the coating significant shear thinning and rapid thixotropic recovery properties.

[0023] A combination of low-VOC film-forming aids and multifunctional defoamers at 0.6–1.5%;

[0024] This allows for a single application of a coating thickness of ≥6mm on a vertical surface without sagging or dripping during spraying.

[0025] Preferably, the preparation method comprises the following steps:

[0026] Sp1: Add all water, 40-70% self-crosslinking elastic emulsion, all pH adjuster and 60-90% dispersant to the main dispersion tank, and stir at 400-700 rpm for 8-12 minutes to form a uniform basic emulsion;

[0027] Sp2: Maintain a rotation speed of 500-900 rpm, first add all the fibers and whiskers in the crack-resistant toughening component, stir until the fibers are completely dispersed, then slowly add the flexible organic heat-insulating particles, and continue to disperse for 12-18 minutes;

[0028] Sp3: Inorganic composite aerogel microspheres, residual emulsion, residual dispersant, and film-forming aid are pre-dispersed in an independent pre-dispersion tank to prepare a stable slurry C with a solid content of 50-68%. The slurry is then circulated using a high-shear homogenizer at 2200-3200 rpm for 8-15 min. The slurry C is then slowly added to the main cylinder of Sp2 via a metering pump, while simultaneously being sheared at 1800-2600 rpm for 10-16 min, with the temperature controlled at ≤42℃.

[0029] Sp4: Reduce the speed to 250-450 rpm, add all the thickening system and other additives, stir for 12-20 minutes for rheological adjustment and homogenization, filter and discharge to obtain the finished coating;

[0030] The total preparation time is controlled within 45 to 65 minutes.

[0031] Preferably, the preparation of the concentrated slurry C in Sp3 is carried out using an online pipeline emulsifying pump with a cooling jacket or a rotor-stator high-shear machine. The material circulates in the pipeline ≥12 times to ensure that the hard shell on the surface of the core-shell aerogel microspheres is not damaged while achieving complete depolymerization and uniform coating dispersion. The viscosity of the concentrated slurry C at 25°C is controlled at 12000~28000mPa·s, which facilitates accurate metering and addition to the main cylinder without causing local demulsification or viscosity abrupt change.

[0032] Beneficial effects

[0033] This invention provides a wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coating. It has the following beneficial effects:

[0034] This invention innovatively introduces core-shell structured inorganic composite aerogel microspheres. By growing a dense inorganic silicate hard shell in situ on the surface of hydrophobic silica aerogel, a "soft core and hard shell" synergistic system is formed. This not only avoids the defects of traditional aerogel powder such as easy agglomeration, sedimentation, and scattering, ensuring that the coating remains highly uniform and stable during long-term storage, but also significantly reduces the thermal bridging effect inside the insulation layer, achieving a dry film thermal conductivity far lower than existing levels. During construction, only a thin layer is needed to achieve excellent thermal insulation performance, greatly simplifying the design and application of external wall insulation systems and roof insulation layers. This meets the urgent need for high-efficiency, lightweight insulation materials in near-zero energy buildings, while reducing material usage and construction procedures, improving the economy and environmental friendliness of overall energy-saving renovation.

[0035] Breakthroughs in wide-temperature-range flexibility, weather resistance, and adhesion durability: Through the organic combination of self-crosslinking elastic emulsion and crack-resistant toughening components (fibers and whiskers compounded to form a three-dimensional interlocking network), the coating forms a highly elastic crosslinked structure after film formation, which can effectively absorb temperature stress, substrate deformation, and external impact, exhibiting excellent low-temperature flexibility and high-temperature aging resistance, avoiding the phenomenon of existing coatings being prone to cracking, powdering, or peeling at extreme temperatures; the dry film has high bonding strength with cement, concrete, and other substrates, excellent elongation at break, and long resistance to water whitening. Even after multiple thermal cycles or long-term exposure to ultraviolet rays and humid environments, it still maintains integrity and functional stability, significantly extending the service life of exterior walls. It is particularly suitable for complex scenarios such as high temperature and humidity in the south, severe cold and dryness in the north, and seamless spraying renovation of old buildings.

[0036] Significantly improved construction friendliness and production controllability: The step-by-step process of "independent pre-dispersion of concentrated slurry C + high-shear pipeline circulation + precise addition by metering pump" ensures that the core-shell aerogel microspheres achieve full depolymerization and uniform coating without damaging the hard shell. The system has excellent rheological properties, with obvious shear thinning and rapid thixotropic recovery capabilities. It supports one-time thick application on vertical surfaces without sagging and high-pressure spraying without dripping. It has high construction tolerance and a smooth and beautiful surface. The entire preparation process is characterized by mild temperature, short time, and universal equipment, which is conducive to industrial-scale production. The finished coating has strong storage stability and does not require frequent stirring, reducing production and transportation costs and promoting the evolution of water-based thermal insulation coatings towards a green, multifunctional, and long-lasting integrated direction. Attached Figure Description

[0037] Figure 1 This is a flowchart illustrating the preparation process of the present invention;

[0038] Figure 2This is a diagram showing the composition of the present invention. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Specific Implementation Example 1:

[0041] like Figures 1 to 2 As shown, the wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coating is a water-dispersion type single-component coating, which includes the following components by weight percentage:

[0042] The coating contains 3–15% flexible organic thermal insulation particles; 4–18% inorganic composite aerogel microspheres, which are core-shell structured particles with silica aerogel as the core and inorganic silicate hard shells grown in situ on the surface, with a shell thickness of 1–6 μm; 0.4–2.0% crack-resistant and toughening components; 14–25% self-crosslinking elastic emulsion; 1.5–4.5% composite functional additives; and 48–62% water. The coating has a Stormer viscosity of 138–165 KU at 25℃, and the thermal conductivity of a 2.5–4.0 mm thick dry film after application is ≤0.040 W / (m·K). It also shows no cracks or powdering after bending at -10℃ and heating in a 150℃ oven for 72 hours.

[0043] Inorganic composite aerogel microspheres are prepared by the following steps: hydrophobic silica aerogel powder is dispersed in a water-alcohol mixture containing a silane coupling agent and an alkaline catalyst, and a precursor mixture of tetraethyl orthosilicate and silica sol is added dropwise. The mixture undergoes in-situ hydrolysis and condensation on the surface of the aerogel particles to form a dense inorganic silicate hard shell. After drying, composite aerogel microspheres with intact core-shell structure and no shell detachment are obtained, with an average particle size of 20-90 μm and a bulk density of 0.22-0.42 g / cm³.

[0044] The flexible organic thermal insulation particles are selected from one or more of closed-cell elastic polyurethane microspheres, thermoplastic polyolefin elastomer foam particles, or recycled rubber micropowder pre-coated with a 2-5% hydrophilic polyvinyl alcohol thin layer. The particle size is 80-350μm and the compression set is ≥60%, so as to provide the coating with stress buffering and flexible deformation capability.

[0045] The crack-resistant and toughening component is composed of modified polypropylene fibers with a length of 1.5 to 6 mm and corundum whiskers or sepiolite whiskers with an average aspect ratio of ≥20 in a weight ratio of 1:0.4 to 1:1.5. It forms a three-dimensional interlocking network in the coating, so that the dry film tensile bond strength is ≥1.1 MPa and the elongation at break is ≥80%.

[0046] The self-crosslinking elastic emulsion is a siloxane-acrylate core-shell emulsion or a waterborne polyurethane-acrylate hybrid emulsion. The emulsion introduces a diacetone acrylamide / adipate dihydrazide room temperature self-crosslinking system with a solid content of 50-56%, a minimum film-forming temperature of ≤5℃, and a crosslinking density after film formation that allows the coating to withstand water whitening for ≥240h.

[0047] Multifunctional additives include:

[0048] The coating contains 0.8–2.2% of a specialized block polyether dispersant for core-shell aerogel microspheres; 0.5–1.8% of a thickening system composed of an associative hydrophobic modified alkali-swelling thickener and a polyurethane rheology modifier, which gives the coating significant shear thinning and rapid thixotropic recovery properties; and 0.6–1.5% of a combination of a low-VOC film-forming aid and a multifunctional defoamer. This results in a single application thickness of ≥6mm on vertical surfaces without sagging or dripping during spraying.

[0049] The preparation method steps are as follows:

[0050] Sp1: Add all water, 40-70% self-crosslinking elastic emulsion, all pH adjuster and 60-90% dispersant to the main dispersion tank, and stir at 400-700 rpm for 8-12 minutes to form a uniform basic emulsion;

[0051] Sp2: Maintain a rotation speed of 500-900 rpm, first add all the fibers and whiskers in the crack-resistant toughening component, stir until the fibers are completely dispersed, then slowly add the flexible organic heat-insulating particles, and continue to disperse for 12-18 minutes;

[0052] Sp3: Inorganic composite aerogel microspheres, residual emulsion, residual dispersant, and film-forming aid are pre-dispersed in an independent pre-dispersion tank to prepare a stable slurry C with a solid content of 50-68%. The slurry is then circulated using a high-shear homogenizer at 2200-3200 rpm for 8-15 min. The slurry C is then slowly added to the main cylinder of Sp2 via a metering pump, while simultaneously being sheared at 1800-2600 rpm for 10-16 min, with the temperature controlled at ≤42℃.

[0053] Sp4: Reduce the speed to 250-450 rpm, add all the thickening system and other additives, stir for 12-20 minutes for rheological adjustment and homogenization, filter and discharge to obtain the finished coating;

[0054] The total preparation time is controlled within 45 to 65 minutes.

[0055] The preparation of concentrated slurry C in Sp3 is carried out using an online pipeline emulsification pump with a cooling jacket or a rotor-stator high-shear machine. The material circulates in the pipeline ≥12 times to ensure that the hard shell on the surface of the core-shell aerogel microspheres is not damaged, while achieving complete depolymerization and uniform coating dispersion. The viscosity of concentrated slurry C at 25℃ is controlled at 12000~28000mPa·s, which facilitates accurate metering and addition to the main cylinder without causing local demulsification or viscosity abrupt change. Specific Implementation Example 2:

[0057] like Figures 1 to 2 As shown, the general-purpose flexible thermal insulation intermediate coating (formula A):

[0058] Formula composition (by weight, 100% total):

[0059] Flexible organic thermal insulation particles: Closed-cell elastic polyurethane microspheres (average particle size 150μm, compression set 68%) 8%;

[0060] Inorganic composite aerogel microspheres: core-shell structure (silica aerogel core, silica shell thickness 3μm, average particle size 45μm, bulk density 0.28g / cm³) 10%;

[0061] Crack-resistant and toughening components: 0.6% modified polypropylene fiber (3mm in length) + 0.4% sepiolite whiskers (25mm aspect ratio) (weight ratio 1:0.67).

[0062] Self-crosslinking elastic emulsion: Siloxane-acrylate core-shell emulsion (solid content 52%, containing DAAM / ADH self-crosslinking system, MFFT 3℃) 18%;

[0063] Multifunctional additives:

[0064] Specialized block polyether dispersant 1.2%;

[0065] Associative hydrophobic modified alkali-swellable thickener 0.6% + polyurethane rheology modifier 0.4%;

[0066] Low VOC film-forming aid (alcohol esters) 0.5% + multifunctional defoamer 0.3%;

[0067] pH adjuster (AMP-95) 0.1%;

[0068] Water: Balance 60.0%.

[0069] Preparation of inorganic composite aerogel microspheres:

[0070] 100g of hydrophobic silica aerogel powder (average particle size 25μm) was dispersed in a water-ethanol mixture (water:ethanol = 7:3, total volume 500mL) containing 3g KH-550 silane coupling agent and 0.5g ammonia (catalyst), and ultrasonically dispersed for 30min. While stirring, a mixed precursor of tetraethyl orthosilicate (TEOS) and silica sol (30% solid content) (TEOS:silica sol = 1:1, total volume 80mL) was added dropwise over a controlled addition time of 2h at a reaction temperature of 40℃. After the reaction, the mixture was centrifuged, washed, and vacuum dried at 80℃ for 8h to obtain composite aerogel microspheres with intact cores and shells, a shell thickness of approximately 3μm, and a bulk density of 0.28g / cm³.

[0071] Coating preparation method:

[0072] Sp1: Add all water (60%), 50% self-crosslinking elastic emulsion (9%), all pH adjuster (0.1%) and 70% dispersant (0.84%) to the main dispersion tank, stir at 500 rpm for 10 min to form a uniform basic emulsion at 25°C.

[0073] Sp2: Maintain a speed of 600 rpm, first add all the modified polypropylene fibers (0.6%) and sepiolite whiskers (0.4%), stir for 8 minutes until the fibers are completely dispersed and tangled; then slowly add flexible organic thermal insulation particles (8%), continue to disperse for 15 minutes until the particles are fully wetted and there are no floating particles.

[0074] Sp3: In an independent pre-dispersion tank, inorganic composite aerogel microspheres (10%) were mixed with the remaining emulsion (9%), remaining dispersant (0.36%), film-forming aid (0.5%), and defoamer (0.3%) to prepare a concentrated slurry C with a solid content of 58%. A high-shear mill with a cooling jacket (2800 rpm) was used, circulating the slurry in the pipeline for 12 minutes (15 cycles). The slurry temperature was controlled to ≤40℃, and the viscosity at 25℃ was approximately 18000 mPa·s. The concentrated slurry C was slowly added to the main cylinder of Sp2 via a peristaltic metering pump (flow rate 5 L / min), while the main cylinder was simultaneously accelerated to 2200 rpm for high-speed shearing for 13 minutes.

[0075] Sp4: Reduce speed to 300 rpm, add all thickening system (0.6% + 0.4%) and other additives, stir for 15 min for rheology adjustment. Filter the product through a 200-mesh filter to obtain the finished coating. Total preparation time: 52 minutes.

[0076] Performance testing:

[0077] Stormer viscosity (25℃): 148KU;

[0078] Thermal conductivity of dry film (3mm thick): 0.038 W / (m·K);

[0079] Low-temperature flexibility: After being 10℃ for 2 hours, it was bent 180° around a Φ30mm round bar without cracking;

[0080] High temperature durability: After drying in a 150℃ oven for 72 hours, the surface showed no powdering or cracking.

[0081] Workability: A 6mm thick layer can be applied to vertical surfaces without dripping.

[0082] Storage stability: No hard sedimentation at 50℃ for 120 hours, and no stratification at room temperature for 12 months. Specific Implementation Example 3:

[0084] like Figures 1 to 2 As shown: High-insulation thin-layer intermediate coating (Formula B):

[0085] Formula composition (by weight, 100% total):

[0086] Flexible organic thermal insulation granules: 5% recycled rubber micro powder (average particle size 200μm, compression set 72%) with a 3% hydrophilic polyvinyl alcohol thin layer pre-coated on the surface;

[0087] Inorganic composite aerogel microspheres: core-shell structure (silica aerogel core, silica shell thickness 2μm, average particle size 35μm, bulk density 0.25g / cm³) 15%;

[0088] Crack-resistant and toughening components: 0.8% modified polypropylene fiber (4mm length) + 0.7% corundum whiskers (30 aspect ratio) (weight ratio 1:0.875).

[0089] Self-crosslinking elastic emulsion: Waterborne polyurethane-acrylate hybrid emulsion (solid content 54%, containing DAAM / ADH self-crosslinking system, MFFT2℃) 16%;

[0090] Multifunctional additives:

[0091] Use 1.8% block polyether dispersant;

[0092] Associative hydrophobic modified alkali-swellable thickener 0.8% + polyurethane rheology modifier 0.6%;

[0093] Low VOC film-forming aid (alcohol esters) 0.7% + multifunctional defoamer 0.4%;

[0094] pH adjuster (AMP-95) 0.1%;

[0095] Water: Balance 58.1%.

[0096] Preparation of inorganic composite aerogel microspheres:

[0097] 150 g of hydrophobic silica aerogel powder (average particle size 20 μm) was dispersed in a water-ethanol mixture containing 4.5 g KH-560 silane coupling agent and 0.8 g ammonia (water:ethanol = 6:4, total volume 750 mL) and ultrasonically dispersed for 25 min. While stirring, a mixed precursor of tetraethyl orthosilicate (TEOS) and silica sol (30% solid content) (TEOS:silica sol = 1:1.2, total volume 120 mL) was added dropwise over 1.5 h at a reaction temperature of 35 °C. After the reaction, the mixture was centrifuged, washed, and vacuum dried at 75 °C for 7 h to obtain composite aerogel microspheres with intact core and shell, a shell thickness of approximately 2 μm, and a bulk density of 0.25 g / cm³.

[0098] Coating preparation method:

[0099] Sp1: Add all water (58.1%), 60% self-crosslinking elastic emulsion (9.6%), all pH adjuster (0.1%) and 80% dispersant (1.44%) to the main dispersion tank and stir at 550 rpm for 9 min to form a uniform basic emulsion at 24°C.

[0100] Sp2: Maintain a speed of 700 rpm, first add all the modified polypropylene fibers (0.8%) and corundum whiskers (0.7%), stir for 7 minutes until the fibers are completely dispersed and entangled; then slowly add flexible organic thermal insulation particles (5%), continue to disperse for 16 minutes until the particles are fully wetted and there are no floating particles.

[0101] Sp3: In an independent pre-dispersion tank, inorganic composite aerogel microspheres (15%) were mixed with the remaining emulsion (6.4%), remaining dispersant (0.36%), film-forming aid (0.7%), and defoamer (0.4%) to prepare a concentrated slurry C with a solid content of 62%. A high-shear mill with a cooling jacket (3000 rpm) was used, circulating the slurry in the pipeline for 14 minutes (18 cycles). The slurry temperature was controlled to ≤38℃, and the viscosity at 25℃ was approximately 21000 mPa·s. The concentrated slurry C was slowly added to the main cylinder of Sp2 via a peristaltic metering pump (flow rate 4 L / min), while the main cylinder was simultaneously accelerated to 2400 rpm for high-speed shearing for 15 minutes.

[0102] Sp4: Reduce speed to 350 rpm, add all thickening system (0.8% + 0.6%) and other additives, stir for 18 min for rheology adjustment. Filter the product through a 200-mesh filter to obtain the finished coating. Total preparation time: 58 minutes.

[0103] Performance testing:

[0104] Stormer viscosity (25℃): 155KU;

[0105] Dry film thermal conductivity (2.5 mm thick): 0.035 W / (m·K);

[0106] Low-temperature flexibility: After being 10℃ for 2 hours, it was bent 180° around a Φ30mm round bar without cracking;

[0107] High temperature durability: After drying in a 150℃ oven for 72 hours, the surface showed no powdering or cracking.

[0108] Tensile bond strength: 1.3 MPa; Elongation at break: 92%;

[0109] Water whitening resistance: ≥280h;

[0110] Suitable for thin-layer spraying construction, a thickness of 2.5mm is sufficient to achieve the insulation requirement of R=1.5m²·K / W. Specific Implementation Example 4:

[0112] like Figures 1 to 2 As shown: Weather-resistant enhanced intermediate coating (Formula C):

[0113] Formula composition (by weight, 100% total):

[0114] Flexible organic thermal insulation particles: 12% thermoplastic polyolefin elastomer foam particles (average particle size 300μm, compression set 65%).

[0115] Inorganic composite aerogel microspheres: core-shell structure (silica aerogel core, silicate shell thickness 5μm, average particle size 70μm, bulk density 0.35g / cm³) 8%;

[0116] Crack-resistant and toughening components: 0.5% modified polypropylene fiber (2mm length) + 0.5% sepiolite whiskers (22 aspect ratio) (weight ratio 1:1);

[0117] Self-crosslinking elastic emulsion: Siloxane-acrylate core-shell emulsion (solid content 53%, containing DAAM / ADH self-crosslinking system, MFFT 4℃) 22%;

[0118] Multifunctional additives:

[0119] Special block polyether dispersant 1.0%;

[0120] Associative hydrophobic modified alkali-swellable thickener 0.5% + polyurethane rheology modifier 0.7%;

[0121] Low VOC film-forming aid (alcohol esters) 0.6% + multifunctional defoamer 0.3%;

[0122] pH adjuster (AMP-95) 0.1%;

[0123] Water: Balance 54.8%.

[0124] Preparation of inorganic composite aerogel microspheres:

[0125] 80 g of hydrophobic silica aerogel powder (average particle size 40 μm) was dispersed in a water-ethanol mixture containing 2.4 g KH-570 silane coupling agent and 0.4 g ammonia (water:ethanol = 8:2, total volume 400 mL) and ultrasonically dispersed for 35 min. While stirring, a mixed precursor of tetraethyl orthosilicate (TEOS) and silica sol (30% solid content) (TEOS:silica sol = 1:0.8, total volume 65 mL) was added dropwise over 2.5 h at a reaction temperature of 45 °C. After the reaction, the mixture was centrifuged, washed, and vacuum dried at 85 °C for 9 h to obtain composite aerogel microspheres with intact core and shell, a shell thickness of approximately 5 μm, and a bulk density of 0.35 g / cm³.

[0126] Coating preparation method:

[0127] Sp1: Add all water (54.8%), 45% self-crosslinking elastic emulsion (9.9%), all pH adjuster (0.1%) and 65% dispersant (0.65%) to the main dispersion tank and stir at 450 rpm for 11 min to form a uniform basic emulsion at 26°C.

[0128] Sp2: Maintain a speed of 800 rpm, first add all the modified polypropylene fibers (0.5%) and sepiolite whiskers (0.5%), stir for 9 minutes until the fibers are completely dispersed and tangled; then slowly add flexible organic thermal insulation particles (12%), continue to disperse for 14 minutes until the particles are fully wetted and there are no floating particles.

[0129] Sp3: In an independent pre-dispersion tank, inorganic composite aerogel microspheres (8%) were mixed with the remaining emulsion (12.1%), remaining dispersant (0.35%), film-forming aid (0.6%), and defoamer (0.3%) to prepare a concentrated slurry C with a solid content of 55%. An online inline emulsification pump with a cooling jacket (2600 rpm) was used for circulation within the pipeline for 10 minutes (14 cycles). The slurry temperature was controlled to ≤42℃, and the viscosity at 25℃ was approximately 15000 mPa·s. The concentrated slurry C was slowly added to the Sp2 main cylinder via a peristaltic metering pump (flow rate 6 L / min), while simultaneously the main cylinder was accelerated to 2000 rpm for high-speed shearing for 12 minutes.

[0130] Sp4: Reduce speed to 400 rpm, add all thickening system (0.5% + 0.7%) and other additives, stir for 16 min for rheology adjustment. Filter the product through a 200-mesh filter to obtain the finished coating. Total preparation time: 50 minutes.

[0131] Performance testing:

[0132] Stormer viscosity (25℃): 142KU;

[0133] Dry film thermal conductivity (4mm thick): 0.039 W / (m·K);

[0134] Low-temperature flexibility: After being 10℃ for 2 hours, it was bent 180° around a Φ30mm round bar without cracking;

[0135] High temperature durability: After drying in a 150℃ oven for 72 hours, the surface showed no powdering or cracking.

[0136] Artificial accelerated aging (QUV2000h): No chalking, color difference ΔE≤2.0;

[0137] Suitable for exterior walls in hot and humid southern regions, with excellent stain resistance. Specific Implementation Example 5:

[0139] like Figures 1 to 2 As shown: Based on Examples 1-4 above, this example further illustrates key precautions, potential problems, and solutions during the preparation process to ensure stable coating quality and repeatable production. All operations are carried out in a clean, well-ventilated workshop with an ambient temperature of 15-30°C and a relative humidity of ≤75% to avoid dust pollution.

[0140] Important notes for SP1 phase:

[0141] Deionized water (conductivity ≤10μS / cm) must be used to prevent ions from interfering with the stability of the emulsion.

[0142] Order of addition: water first → pH adjuster → dispersant → part of emulsion. If slight foaming occurs in the initial stirring stage, 0.05% defoamer can be added to suppress it.

[0143] Potential problem: Localized emulsion breakdown (manifested as oil droplets floating on the surface). Solution: Check the emulsion pH (should be controlled between 7.5 and 8.5). If it is too low, add a small amount of ammonia to adjust it; do not exceed 700 rpm when stirring to avoid excessive shearing.

[0144] Important notes for Sp2 phase:

[0145] When adding fibers and whiskers, dry premixing (tumbling in a V-mixer for 5 minutes) is necessary to prevent fiber clumping. After addition, observe the cylinder wall; if fibers stick to the wall, use a scraper to assist.

[0146] The addition rate of flexible organic thermal insulation particles should be ≤5kg / min, and the viscosity of the system should be observed while adding the particles.

[0147] Potential problem: particle flotation or sedimentation. Solution: If the particle surface is not hydrophilic enough, a 0.2% wetting agent aqueous solution can be sprayed into the particles beforehand; if the stirring time is insufficient and causes uneven dispersion, extend the stirring time by 2-3 minutes and take samples for microscopic examination (no particle agglomeration).

[0148] Points for attention in the Sp3 stage:

[0149] Before the preparation of thick slurry C, the inorganic composite aerogel microspheres must be stored in a dry environment (humidity ≤ 40%), and the remaining part should be sealed immediately after opening the bag to prevent the shell layer from softening due to moisture absorption.

[0150] During the high-shear circulation process, the temperature of the slurry should be monitored in real time (recorded every 2 minutes). If it exceeds 42°C, the circulation should be paused and cooled with cooling water. The pipeline system must be pre-cleaned (circulate with hot water + neutral detergent for 30 minutes).

[0151] When pumping into the main cylinder, the flow rate error of the metering pump should be ≤ 5% to avoid instantaneous demulsification caused by too high local solid content.

[0152] Potential problem: Insufficient depolymerization of aerogel (flocculants in the slurry). Solution: Increase the number of circulation times to 20 times, or increase the rotation speed by 100 rpm (upper limit 3200 rpm); if the shell layer is slightly damaged (observed by SEM), reduce the rotation speed by 200 rpm and extend the circulation time.

[0153] Points for attention in the Sp4 stage:

[0154] Before adding the thickener, it must be pre-dissolved into a slurry with water or film-forming auxiliaries (solid content 30 - 40%) to prevent caking.

[0155] After the final stirring, take a sample to measure the viscosity (Stormer instrument, 25°C). If it is too low, add 0.1% thickener; if it is too high, dilute it with a small amount of water (≤ 1%).

[0156] The mesh number of the filter screen is 200 - 300 meshes, and the qualified filter residue rate is ≤ 0.5%. The finished paint should be immediately sealed and stored away from light.

[0157] Potential problem: Stratification or bubbling of the finished product. Solution: Let it stand for 10 minutes for defoaming after homogenization, or vacuum defoaming (-0.08 MPa, 5 minutes); shake well and test before storage.

[0158] Overall quality control:

[0159] Take 3 samples (upper, middle, and lower layers) for each batch to detect the viscosity consistency (difference ≤ 5 KU).

[0160] Cleaning of production equipment: At the end of each shift, circulate and clean the dispersion tank and pipeline with warm water + 5% neutral detergent to prevent cross-contamination.

[0161] Safety notice: Operators should wear dust masks and gloves; although the aerogel powder is coated with a core-shell structure, it is still necessary to avoid inhaling it for a long time.

[0162] By following the above precautions, the qualified rate of the finished product can be improved. Specific Implementation Example Six:

[0164] like Figures 1 to 2 As shown: This embodiment, based on the preparation methods of Examples 1-5, further explores the feasibility of process parameter optimization and large-scale production to ensure the consistency and economy of the coating in industrial production. The experiment was conducted on a pilot production line with a capacity of 10 tons / batch, using an automated control system to monitor key parameters. The environmental conditions were a temperature of 20-28℃ and a relative humidity of ≤70%.

[0165] Process optimization details:

[0166] Sp1 stage: The pH of the base emulsion is monitored in real time by an online pH sensor, and a pH adjuster is automatically added (error ±0.1%) to ensure that the system pH is stable at 7.8–8.2, reducing the risk of emulsion demulsification. The stirring blades are optimized to an anchor-type + dispersion disc combination, reducing the residual material rate in dead corners to ≤0.3%.

[0167] Sp2 stage: A twin-shaft mixer (600 rpm main shaft + 200 rpm secondary shaft) is introduced to improve the dispersion efficiency of fibers and whiskers, shorten the mixing time to 12 min, and monitor the temperature inside the cylinder (≤30℃) with an infrared thermometer to prevent local overheating from causing particle adhesion.

[0168] Sp3 stage: The preparation of concentrated slurry C adopted a series pipeline emulsification pump (two-stage shearing, speed 2800rpm + 2500rpm), the number of cycles was optimized to 15, the circulation flow rate was controlled at 200L / h, and the slurry viscosity deviation was ≤3%. The main cylinder shearing adopted frequency conversion speed regulation, initially 2000rpm, gradually increasing to 2400rpm at the end, optimizing the shear force distribution and reducing the damage rate of aerogel microsphere shells to ≤0.1% (SEM detection).

[0169] Sp4 stage: Thickener is added through a high-pressure homogenizing nozzle (pressure 0.5MPa) to improve dissolution uniformity; the filtration system is upgraded to a two-stage vibrating screen (200 mesh + 300 mesh), reducing the filter residue rate to 0.2% and improving the purity of the finished product.

[0170] Scalable validation:

[0171] Five batches (10 tons each) were produced consecutively. The Stormer viscosity (25℃) fluctuated within the range of 142 to 150 KU, and the thermal conductivity (3mm thick) was 0.036 to 0.039 W / (m·K). The performance consistency between batches was ≥98%.

[0172] Production energy consumption: Each ton of coating consumes approximately 120 kWh of electricity and 0.8 m³ of water, which is 15% lower than the traditional dispersion process.

[0173] Equipment maintenance: After each batch, clean the pipes with warm water and 3% neutral detergent for 30 minutes in a circulating manner. The pipe residue rate should be ≤0.5% to ensure no cross-contamination.

[0174] Performance testing:

[0175] Low-temperature flexibility: After being 10℃ for 2 hours, it can be bent 180° around a Φ30mm round bar without cracking (GB / T 16777 standard).

[0176] High temperature durability: After 72 hours at 150°C, the surface shows no powdering or cracking (adapted from ASTM D4587).

[0177] Workability: No dripping when applied to a vertical surface with a 6.5mm trowel; no sagging when sprayed (pressure 0.4MPa); film smoothness ≤0.2mm (laser leveling instrument).

[0178] Storage stability: No hard sedimentation at 50℃ for 120 hours, no stratification at room temperature for 18 months (ISO 13007 standard). Specific Implementation Example 7:

[0180] like Figures 1 to 2 As shown: This embodiment is based on the wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coating of Examples 1-5 (hereinafter referred to as "the coating of this invention"), and conducts a parallel comparative experiment with three commercially available traditional insulation materials, including:

[0181] Comparison Sample 1: Traditional aerogel thermal insulation coating (direct addition of hydrophobic SiO2 aerogel powder, without core-shell structure).

[0182] Comparison Sample 2: EPS board external insulation system (expanded polystyrene board + polymer mortar).

[0183] Comparison Sample 3: Ordinary elastic acrylic thermal insulation intermediate coating (containing rubber particles, without aerogel).

[0184] Experimental conditions:

[0185] Sample preparation: The coating of this invention was sprayed to a thickness of 3 mm; the coating thickness of control sample 1 was 6 mm; the coating thickness of control sample 2 was 50 mm + 5 mm of mortar; the coating thickness of control sample 3 was 5 mm. All samples were cured for 28 days under standard conditions (23±2℃, 50±5%RH).

[0186] Substrate: Cement mortar board (300×300×10mm) is used uniformly.

[0187] Testing instruments: Thermal conductivity (Netzsch HFM 436); Viscosity (Stormer viscometer); Low temperature flexibility (self-made bending device + microscope); High temperature durability (oven + colorimeter); Tensile strength (Instron 5567); Storage stability (constant temperature chamber).

[0188] Each test was performed in 5 parallel groups, and the average value was taken.

[0189] Test Project The coating of this invention (3mm thick) Comparison Sample 1 Comparison Sample 2 Comparison Sample 3 thermal conductivity 0.037 0.062 0.038 equivalent 0.075 Stormer viscosity 148 162 Not applicable (for sheet materials) 135 Low-temperature flexibility (180° bending at -10℃, Φ30mm round bar) No cracks Microcracks Brittle fracture of the board Obvious cracks High temperature durability No powdering Slight powdering mortar layer cracking Severe pulverization Tensile bond strength (MPa) 1.25 0.72 0.45 (mortar layer) 0.81 Elongation at break 88 45 Not applicable (rigid) 62 Storage stability No layering, no sedimentation Layering (supernatant 20mm) not applicable slight settlement Construction thickness ≥6 ≤4 Fixed 50+ ≤5

[0190] This embodiment, through quantitative comparison, fully demonstrates the comprehensive superiority of the coating of the present invention in terms of thermal insulation efficiency, flexibility and durability, and convenient construction, overcoming the defects of traditional materials such as thickness dependence, easy cracking and poor stability.

[0191] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. Wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coating, which is a water-dispersion type single-component coating, comprising the following components by weight percentage: Flexible organic thermal insulation particles, 3-15%; The inorganic composite aerogel microspheres comprise 4-18% of the total content. These inorganic composite aerogel microspheres are core-shell structured particles with silica aerogel as the core and an inorganic silicate hard shell grown in situ on the surface. The shell thickness is 1-6 μm. Crack-resistant and toughening components: 0.4–2.0%; 14-25% self-crosslinking elastic emulsion; Composite functional additives: 1.5–4.5%; Water content: 48-62%; Its features are, The coating has a Stormer viscosity of 138–165 KU at 25°C, and the thermal conductivity of a 2.5–4.0 mm thick dry film after application is ≤0.040 W / (m·K). Furthermore, it shows no cracking or powdering after being bent at -10°C and heated in an oven at 150°C for 72 hours.

2. The wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coating according to claim 1, characterized in that, The inorganic composite aerogel microspheres are prepared by the following steps: hydrophobic silica aerogel powder is dispersed in a water-alcohol mixture containing a silane coupling agent and an alkaline catalyst, and a precursor mixture of tetraethyl orthosilicate and silica sol is added dropwise. The mixture undergoes in-situ hydrolysis and condensation on the surface of the aerogel particles to form a dense inorganic silicate hard shell. After drying, composite aerogel microspheres with intact core-shell structure and no shell detachment are obtained, with an average particle size of 20-90 μm and a bulk density of 0.22-0.42 g / cm³.

3. The wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coating according to claim 1, characterized in that, The flexible organic thermal insulation particles are selected from one or more of closed-cell elastic polyurethane microspheres, thermoplastic polyolefin elastomer foam particles, or reclaimed rubber micropowder pre-coated with a 2-5% hydrophilic polyvinyl alcohol thin layer, with a particle size of 80-350 μm and a compression set ≥60%, to provide coating stress buffering and flexible deformation capability.

4. The wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coating according to claim 1, characterized in that, The crack-resistant and toughening component is composed of modified polypropylene fibers with a length of 1.5 to 6 mm and corundum whiskers or sepiolite whiskers with an average aspect ratio of ≥20 in a weight ratio of 1:0.4 to 1:1.

5. It forms a three-dimensional interlocking network in the coating, so that the dry film tensile bond strength is ≥1.1 MPa and the elongation at break is ≥80%.

5. The wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coating according to claim 1, characterized in that, The self-crosslinking elastic emulsion is a siloxane-acrylate core-shell emulsion or a waterborne polyurethane-acrylate hybrid emulsion. A diacetone acrylamide / adipate dihydrazide room temperature self-crosslinking system is introduced into the emulsion. The solid content is 50-56%, the minimum film-forming temperature is ≤5℃, and the crosslinking density after film formation makes the coating water-resistant whitening time ≥240h.

6. The wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coating according to claim 1, characterized in that, The composite functional additive comprises: 0.8–2.2% of a specialized block polyether dispersant for core-shell aerogel microspheres; A thickening system composed of an associative hydrophobic modified alkali-swellable thickener and a polyurethane rheology modifier, at a concentration of 0.5–1.8%; The combination of low-VOC film-forming aid and multifunctional defoamer is 0.6-1.5%.

7. A method for preparing a wide-temperature-range self-crosslinking core-shell aerogel building insulation intermediate coating according to any one of claims 1 to 6, characterized in that, Includes the following steps: Sp1: Add all water, 40-70% self-crosslinking elastic emulsion, all pH adjuster and 60-90% dispersant to the main dispersion tank, and stir at 400-700 rpm for 8-12 minutes to form a uniform basic emulsion; Sp2: Maintain a rotation speed of 500-900 rpm, first add all the fibers and whiskers in the crack-resistant toughening component, stir until the fibers are completely dispersed, then slowly add the flexible organic heat-insulating particles, and continue to disperse for 12-18 minutes; Sp3: Inorganic composite aerogel microspheres, residual emulsion, residual dispersant, and film-forming aid are pre-dispersed in an independent pre-dispersion tank to prepare a stable slurry C with a solid content of 50-68%. The slurry is then circulated using a high-shear homogenizer at 2200-3200 rpm for 8-15 min. The slurry C is then slowly added to the main cylinder of Sp2 via a metering pump, while simultaneously being sheared at 1800-2600 rpm for 10-16 min, with the temperature controlled at ≤42℃. Sp4: Reduce the speed to 250-450 rpm, add all the thickening system and other additives, stir for 12-20 minutes for rheological adjustment and homogenization, filter and discharge to obtain the finished coating; The total preparation time is controlled within 45 to 65 minutes.

8. The preparation method according to claim 7, characterized in that, The preparation of the concentrated slurry C in Sp3 is carried out using an online pipeline emulsifying pump with a cooling jacket or a rotor-stator high-shear machine. The material circulates in the pipeline ≥12 times to ensure that the hard shell on the surface of the core-shell aerogel microspheres is not damaged, while achieving complete depolymerization and uniform coating dispersion. The viscosity of the concentrated slurry C at 25℃ is controlled at 12000~28000mPa·s, which facilitates accurate metering and addition to the main cylinder without causing local demulsification or viscosity abrupt change.

Images