An aerogel interior wall insulation putty based on a magnesium phosphate-silane bridging interface, its preparation method and application

Abstract

This invention discloses an aerogel interior wall insulation putty based on a magnesium phosphate-silane bridging interface, its preparation method, and its application. Addressing the technical bottleneck of traditional aerogel putties that require large amounts of organic adhesive powder to achieve bonding strength, leading to decreased fire resistance and excessive VOCs, this invention pioneers a low-alkalinity magnesium phosphate inorganic gel system combined with an aminosilane-bridging modified aerogel crosslinking network. This is achieved through the interaction of the -NH2 groups of KH-550 aminosilane with the [PO4] groups in the magnesium phosphate salt bridging network. 3‑ It forms strong P-N chemical bonds, achieving ultra-high bonding strength with extremely low organic content. According to tests, its standard state bonding strength is ≥0.95MPa, and after immersion in water it is ≥0.65MPa; thermal conductivity is ≤0.035W / (m·K); total calorific value is ≤0.5MJ / kg; furnace temperature rise is ≤15℃; continuous combustion time is 0s; and fire resistance reaches A1 level; furthermore, VOCs, formaldehyde, and heavy metals were not detected. This invention truly achieves a perfect unity of ultimate thermal insulation, absolute A1-level non-combustibility, and zero VOCs, making it suitable for high-end green building interior wall insulation systems.

Description

Technical Field

[0001] This invention belongs to the field of building energy-saving materials and special coatings technology. Specifically, it relates to a thermal insulation putty with ultra-low thermal conductivity, ultra-high bonding strength, A1 fire resistance, and zero VOC emissions. More specifically, this invention relates to an interior wall thermal insulation putty based on the synergistic effect of a magnesium phosphate inorganic gel system and an aminosilane-bridged modified aerogel, and its preparation method. Background Technology

[0002] Building energy conservation has become a key area for energy saving and emission reduction. A significant portion of energy is lost through building envelopes, particularly walls. Interior wall insulation, as an effective supplement to exterior wall insulation, or even the only option in the renovation of historical buildings and the refurbishment of old residential areas, is experiencing a growing market demand.

[0003] Traditional interior wall insulation materials mainly use polystyrene foam boards (EPS / XPS), polyurethane boards (PU), or rock wool boards, etc. However, these traditional board systems have significant limitations: on the one hand, organic insulation boards (such as EPS and PU) are highly flammable, posing a significant fire hazard, and release large amounts of toxic fumes when burning, failing to meet the stringent fire safety requirements for interior walls; on the other hand, inorganic boards (such as rock wool boards), while fire-resistant, suffer from problems such as easy water absorption, powdering, complex construction, large space occupation, and potential skin allergies. Therefore, coating-like, thin-layer insulation putty / coatings have emerged.

[0004] In recent years, silica (SiO2) aerogel has been hailed as a "miracle material that changes the world" due to its unique nanoporous network structure (porosity as high as 90%~99%, pore size much smaller than the mean free path of air molecules). Its thermal conductivity at room temperature can be as low as 0.012~0.020 W / (m·K). Incorporating aerogel into building insulation putty requires only a few millimeters of application to achieve the insulation effect of several centimeters of traditional insulation materials, greatly saving indoor space.

[0005] However, aerogel thermal insulation putty has encountered a serious technical bottleneck in the actual promotion and industrialization process, namely, it is difficult to simultaneously achieve ultra-low thermal conductivity, high bonding strength (and water resistance) and A1-level non-combustibility (and zero VOC emissions).

[0006] Specifically, this technological bottleneck manifests itself in the following three contradictory aspects:

[0007] First, there are challenges related to interfacial compatibility and dispersibility. To prevent moisture from the building environment from penetrating into the aerogel and damaging its nanopores (once moisture enters, the thermal conductivity increases exponentially), hydrophobic silica aerogels are typically used in engineering. However, hydrophobic aerogels lack active groups on their surface and exhibit strong interfacial repulsion with aqueous systems and inorganic cementing materials (such as cement and gypsum), leading to severe agglomeration and easy stratification of the aerogel powder in the slurry. If high shear forces are forcibly applied during mixing to disperse it, the fragile three-dimensional network framework of the aerogel will be irreversibly damaged, causing it to lose its thermal insulation properties.

[0008] Secondly, there is a contradiction between bonding strength and A1-level fire resistance and environmental performance. Due to the large specific surface area and strong hydrophobicity of aerogel, the cohesion of the putty system is extremely poor. In conventional technical approaches, in order to ensure that this putty containing a large amount of hydrophobic lightweight aggregate can adhere firmly to the wall and meet the high bonding strength requirements of JG / T298-2010 regarding standard conditions and after immersion in water, formulation developers often have to add large amounts of organic polymer binders (such as redispersible latex powder VAE, acrylic emulsions, etc.), often as high as 10% to 20%. This compromise has disastrous consequences: the large amount of organic adhesive powder directly leads to a significant increase in the total calorific value of the putty system. According to the standards GB / T8624-2012 and GB / T14402-2007, A1-level non-combustible materials require a total calorific value ≤2.0 MJ / kg, which means that the total amount of organic matter in the system must be strictly controlled within an extremely low range. Traditional aerogel putty with high adhesive powder content typically only achieves an A2 or B1 grade and releases toxic fumes at high temperatures, failing the stringent tests of GB / T5464-2010 (furnace temperature rise ≤30℃, continuous burning time 0s). Furthermore, the introduction of large amounts of organic adhesive powder inevitably introduces harmful substances such as VOCs and formaldehyde, severely violating the extremely high environmental protection requirements for interior walls stipulated in GB18582-2020.

[0009] Third, the strong alkalinity of traditional silicate cement corrodes the aerogel skeleton. Some patents attempt to use inorganic cement as the main binder to improve fire resistance. However, ordinary silicate cement produces a large amount of calcium hydroxide (Ca(OH)2) during hydration, and the pH value of its hydrated liquid phase often exceeds 12.5. Silica aerogel is essentially amorphous silicic acid, which undergoes a dissolution reaction (depolymerization to form soluble silicates) in a strongly alkaline environment, causing the aerogel's pore structure to gradually collapse, resulting in a significant decrease in its thermal insulation performance after several months.

[0010] In summary, existing aerogel thermal insulation putty technologies are all limited to simple repairs of traditional organic resin + inorganic filler systems, and have never been able to break out of the technical vicious cycle of adding adhesive powder to increase strength but reducing fire resistance, and not adding adhesive powder to increase fire resistance but having no strength.

[0011] Therefore, there is an urgent need in this field for a novel and innovative underlying material system design that can completely solve this global problem through a new gelation mechanism and interface engineering. Summary of the Invention

[0012] The present invention aims to overcome the defects of the prior art. Its primary objective is to provide an original and innovative aerogel interior wall insulation putty that can completely break the "impossible triangle" between high bonding strength, A1 grade absolute non-combustibility, zero VOC release and ultra-low thermal conductivity in aerogel insulation putty.

[0013] Another objective of this invention is to provide a method for preparing the above-mentioned aerogel interior wall insulation putty. This method is scientifically sound and can protect the aerogel pore structure to the greatest extent, making it suitable for large-scale industrial production.

[0014] To achieve the above objectives, the present invention provides an aerogel interior wall insulation putty based on a magnesium phosphate-silane bridging interface. The insulation putty is composed of a dry powder component and water, wherein the dry powder component comprises the following raw materials by weight:

[0015] Reburned magnesium oxide: 15-30 parts;

[0016] Potassium dihydrogen phosphate: 5-15 parts;

[0017] Retarder: 0.5~2.5 parts;

[0018] Aminosilane-modified hydrophobic silica aerogel powder: 8-18 parts;

[0019] Hollow glass microspheres: 10-25 parts;

[0020] Inorganic rheology modifier: 1-4 parts;

[0021] Cellulose ether: 0.1~0.3 parts.

[0022] In this aerogel interior wall insulation putty solution, the re-burned magnesium oxide is dead-burned magnesium oxide obtained by calcination at 1500℃~1700℃, with a specific surface area of ​​150~250m² / kg and an active content of 40%~60%.

[0023] In this aerogel interior wall insulation putty solution, the aminosilane modified hydrophobic silica aerogel powder is prepared by surface grafting modification of hydrophobic silica aerogel and γ-aminopropyltriethoxysilane (KH-550) at a weight ratio of 100:(2~5).

[0024] Furthermore, the hydrophobic silica aerogel has a porosity ≥90%, a specific surface area ≥600m² / g, a water contact angle ≥150°, and a particle size range of 10~50μm.

[0025] In this aerogel interior wall insulation putty solution, the retarder is one or a combination of sodium tetraborate, boric acid, or sucrose.

[0026] In this aerogel interior wall insulation putty solution, the inorganic rheology modifier is synthetic magnesium lithium silicate or high-purity attapulgite.

[0027] In this aerogel interior wall insulation putty solution, the true density of the hollow glass microspheres is 0.15~0.25g / cm³, and the compressive strength is ≥2MPa.

[0028] To achieve the above objectives, the present invention also provides a method for preparing the above-mentioned aerogel interior wall insulation putty, which includes the following steps:

[0029] S1. Aerogel modification: KH-550 was dissolved in anhydrous ethanol to prepare a modification solution with a mass concentration of 5%. The solution was sprayed evenly on the surface of hydrophobic silica aerogel powder and reacted in a closed stirring at 80~100℃ for 1~2h. Then, it was vacuum dried at 110-130℃ to obtain aminosilane modified hydrophobic silica aerogel powder.

[0030] S2. Dry powder mixing: Add the calcined magnesium oxide, potassium dihydrogen phosphate, retarder, inorganic rheology modifier and cellulose ether into a gravity-free mixer and mix at low speed for 10-15 minutes until uniform.

[0031] S3, Lightweight aggregate composite: Add hollow glass microspheres and aminosilane-modified hydrophobic silica aerogel powder obtained in step S1 to the mixture in step S2, and mix with low shear force for 15-20 minutes to obtain thermal insulation putty dry powder.

[0032] S4. Add water and mix: When using, add water at a mass ratio of dry powder to water of 1:(0.6~0.9), stir well and it is ready for application.

[0033] The aerogel interior wall insulation putty provided by this invention is particularly suitable for use in interior wall insulation coating systems of green buildings and ultra-low energy consumption buildings.

[0034] Compared with the prior art, the present invention has the following breakthrough technical effects:

[0035] 1. Breakthrough in High Strength and Water Resistance: Overcoming the industry challenge of achieving high bonding strength with low organic content. Tests show that the putty's bonding strength in standard condition is ≥0.95MPa, and its bonding strength after immersion in water is ≥0.65MPa. Water resistance testing showed no blistering, cracking, or powdering after 48 hours.

[0036] 2. Excellent thermal insulation performance: It effectively protects the nanopores of the aerogel from being penetrated and destroyed by the matrix. Combined with glass microspheres, it has an extremely low thermal conductivity. According to GB / T 10294-2008, the thermal conductivity is stable between 0.030~0.035W / (m·K), achieving the ultimate thermal insulation.

[0037] 3. True A1 fire resistance and extremely low calorific value: After testing according to the standard GB / T5464-2010, the furnace temperature rise is controlled at around 10℃, the mass loss rate is between 15% and 18%, and the continuous combustion time is absolutely 0 seconds. According to GB / T14402-2007 testing, the total calorific value is less than 0.5 MJ / kg, fully meeting the A1 fire performance rating specified in GB / T8624-2012.

[0038] 4. Ultimate safety and environmental protection: Free from traditional glues, resins and other polymers. According to GB18582-2020 testing, VOC content, formaldehyde content, total benzene series content, total lead content and soluble heavy metal content were all undetectable, making it a truly green and healthy building material.

[0039] 5. Aging resistance and substrate protection: The slightly acidic / neutral environment of magnesium phosphate gel eliminates the alkaline leaching corrosion of aerogel by traditional cement, ensuring that the putty has the same lifespan as the building. Detailed Implementation

[0040] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further explained below with reference to specific examples.

[0041] Through a thorough study of existing technical solutions and the problems they face, this invention abandons the traditional physical mixing system of silicate cement / gypsum and redispersible latex powder, that is, it abandons the physical film-forming mechanism of traditional organic adhesive powder providing adhesion, and creatively proposes a biomimetic crosslinking network based on magnesium phosphate (MPC) inorganic gel system and aminosilane (KH-550) bridging modified aerogel.

[0042] Based on this innovative technical solution, this invention provides a formulation for an aerogel interior wall insulation putty based on a magnesium phosphate-silane bridging interface. This insulation putty formulation consists of a dry powder component and water, wherein the dry powder component, by weight, comprises the following raw materials:

[0043] Reburned magnesium oxide: 15-30 parts;

[0044] Potassium dihydrogen phosphate: 5-15 parts;

[0045] Retarder (borax): 0.5~2.5 parts;

[0046] Aminosilane-modified hydrophobic silica aerogel powder: 8-18 parts;

[0047] Hollow glass microspheres: 10-25 parts;

[0048] Inorganic rheology modifier (synthetic magnesium lithium silicate): 1-4 parts;

[0049] Cellulose ether (HPMC): 0.1~0.3 parts.

[0050] To achieve the superior performance of this invention, the following specific synergistic formulation scheme is further provided:

[0051] In this formula, the recalcined magnesium oxide is preferably dead-burned magnesium oxide obtained by calcination at 1500℃~1700℃, with a specific surface area of ​​150~250m² / kg and an activity content of 40%~60%, in order to reduce the initial hydration activity and prevent flash coagulation.

[0052] Accordingly, 15-30 parts of reburned magnesium oxide and 5-15 parts of potassium dihydrogen phosphate (KDP) were further selected as the matrix cementitious material, and 0.5-2.5 parts of retarder were added to ensure an open construction time of approximately 45-90 minutes. This magnesium phosphate cement (MPC) system undergoes a typical acid-base neutralization hydration reaction to generate a high-strength crystalline phase of potassium magnesium phosphate hexahydrate (MgKPO4·6H2O).

[0053] The resulting gelling system, as one of the core innovations of this invention, offers the following three key advantages:

[0054] Firstly, hydration consumes a large amount of free water, and the reaction process rapidly captures free water in the system and enters the crystal lattice, fundamentally blocking the penetration of liquid water into the aerogel nanopores and protecting the thermal insulation framework.

[0055] Secondly, the near-neutral / slightly acidic environment, unlike the strongly alkaline silicate cement, the hydration environment of the MPC system has a pH between 6.5 and 8.5. This mild environment perfectly avoids the chemical erosion of the amorphous silica aerogel skeleton by alkaline ions, giving the material excellent durability.

[0056] Third, the products are all inorganic mineral crystals, which essentially endow the putty with an extremely low calorific value, providing the material basis for achieving ultra-low furnace temperature rise.

[0057] Furthermore, the retarder in this formulation is preferably one or a combination of sodium tetraborate (borax), boric acid, or sucrose.

[0058] Furthermore, the aminosilane-modified hydrophobic silica aerogel powder in this formulation provides the main thermal blocking effect (air molecules within the nanopores lose their ability to conduct heat through convection and heat transfer), and 8 to 18 parts are preferably used. If the amount is less than 8 parts, a sufficient thermal blocking network cannot be constructed, and the thermal conductivity is difficult to reduce to below 0.035 W / (m·K); if the amount is more than 18 parts, due to its extremely low bulk density, the powder bulk density of the system will be too low, and the inorganic cementitious material will not be able to form a continuous stress transfer network, resulting in strength collapse.

[0059] As further explained, the aerogel powder was prepared by surface grafting modification of hydrophobic silica aerogel with KH-550 (γ-aminopropyltriethoxysilane) at a weight ratio of 100:(2~5). After KH-550 modification, the aerogel surface was grafted with reactive amino groups (-NH2), which provide a key reaction anchor for the inorganic-organic chemical bridging in this invention.

[0060] Furthermore, the hydrophobic silica aerogel here has a porosity of ≥90%, a specific surface area of ​​≥600m² / g, a water contact angle of ≥150°, and a particle size range of 10~50μm.

[0061] Furthermore, the hollow glass microspheres in this formula are selected in quantities of 10-25 parts, with a true density of 0.15-0.25 g / cm³ and a compressive strength ≥2 MPa. In this formula, the hollow glass microspheres not only serve as a secondary lightweight aggregate for thermal insulation, synergistically constructing a two-tiered thermal insulation network of macropores and micropores with aerogel, but also play a crucial protective role at the physical level. Under the shear stress experienced during the high-speed mixing and application of the putty, the rigid hollow glass microspheres with high compressive strength can withstand and disperse most of the mechanical destructive force, acting like a layer of physical armor to protect the fragile aerogel powder from crushing, ensuring the full performance of its thermal insulation properties.

[0062] Furthermore, the inorganic rheology modifier in this formulation is preferably synthetic magnesium lithium silicate (for example, the commercial name Laponite is used) or high-purity attapulgite clay; 1 to 4 parts are selected. Traditional putty relies on organic cellulose or starch ethers to provide thickening and thixotropy, but this increases the total calorific value and VOCs. This invention uses pure inorganic synthetic silica (such as Laponite), which is exfoliated in water into charged disk-shaped nanocrystals with a diameter of about 25 nm and a thickness of about 1 nm. The edges of the crystals are positively charged, and the surface is negatively charged. Electrostatic attraction causes them to rapidly form a three-dimensional gel network in a static state, giving the putty excellent anti-sagging properties; when subjected to construction stress, the network disintegrates instantly, exhibiting excellent smooth workability. The pure inorganic properties contribute to the A1 fire resistance rating.

[0063] Furthermore, the cellulose ether (e.g., HPMC) in this formulation is preferably 0.1 to 0.3 parts, mainly as an auxiliary water-retaining agent to prevent the putty layer from losing water too quickly on the porous substrate, which would lead to incomplete hydration of MPC. This extremely low dosage ensures that the impact on the overall system's calorific value is negligible.

[0064] In response to the above-mentioned formulation scheme of aerogel interior wall insulation putty based on magnesium phosphate-silane bridging interface, this invention further provides the corresponding preparation process of aerogel interior wall insulation putty.

[0065] Specifically, the method for preparing aerogel interior wall insulation putty based on the magnesium phosphate-silane bridging interface provided in this invention mainly includes the following steps:

[0066] Includes the following steps:

[0067] S1. Aerogel Modification Steps: Dissolve the prescribed amount of KH-550 in anhydrous ethanol to prepare a modification solution with a mass concentration of 3%~8%; spray the modification solution evenly onto the surface of the continuously stirred hydrophobic silica aerogel powder in the form of a spray; then, stir and react in a closed environment at 80~100℃ for 1~2 hours to fully graft KH-550; finally, vacuum dry the product at 110~130℃ to remove ethanol and water generated by condensation, and obtain aminosilane modified hydrophobic silica aerogel powder after cooling.

[0068] S2. Basic dry mixing step: Add the formulated amounts of calcined magnesium oxide, potassium dihydrogen phosphate, retarder, inorganic rheology modifier and cellulose ether into a gravity-free mixer and mix at low speed for 10-15 minutes to obtain a uniform base premix.

[0069] S3. Low-shear compounding step: Add the prescribed amount of hollow glass microspheres and the aminosilane-modified hydrophobic silica aerogel powder prepared in step S1 to the base material premix obtained in step S2; use a plow mixer to mix for 15-20 minutes under low shear force conditions of 30-50 r / min to ensure that the lightweight aggregate and base material are fully and uniformly dispersed and compounded, thus obtaining the thermal insulation putty dry powder. The key to this step is to use a low-shear force mixing method to protect the particle structure integrity of the aerogel and hollow glass microspheres.

[0070] S4. On-site mixing steps: When using, mix the thermal insulation putty powder obtained in step S3 with water at a mass ratio of 1:(0.6~0.9), and use a mechanical low-speed stirrer until a uniform paste without particles is formed. Then, it can be applied by scraping or other methods.

[0071] Based on the above formulation and preparation scheme, it can be seen that the present invention completely abandons the physical film-forming mechanism of traditional organic adhesive powders (such as redispersible latex powders and VAEs) providing adhesion. Instead, it innovatively uses a cross-scale chemical bonding technology based on amino (organic)-phosphate (inorganic) covalent coordination networks to form aerogel interior wall insulation putty, as detailed below:

[0072] (1) In the initial stage of mixing with water, the KH-550 aminosilane on the surface of the modified aerogel undergoes slight hydrolysis upon contact with water, and its free amino groups (-NH2) exhibit significant basicity and lone pair electron characteristics. At the same time, potassium dihydrogen phosphate (KH2PO4) in the matrix rapidly dissociates into [H2PO4]⁻ and polyphosphate ions. In the early stage of gelation, the highly active amino groups (-NH2) interact strongly with phosphate ions through acid-base proton transfer, first forming a hydrogen bond network, and then dehydrating and condensing in the local microenvironment to form stable phosphoramide bonds (PN bonds) or strong coordination complexes (PO…HN). This process firmly anchors the aerogel particles, which are originally strongly hydrophobic and extremely repulsive to inorganic cement, into the three-dimensional crystal network of potassium magnesium phosphate hydration products. This is an atomic-level chemical connection, rather than the physical encapsulation of traditional adhesive powder. Therefore, even when the total organic content is less than 1.5%, it still exhibits amazing tensile bond strength on a macroscopic scale.

[0073] (2) The strength of traditional cement-based aerogel putty decreases significantly after soaking in water (usually below 0.3 MPa). In contrast, the bonding strength of this invention remains above 0.65 MPa after soaking in water, fully meeting or even exceeding the JG / T298-2010 standard. The mechanism is as follows: on the one hand, after the ethoxy groups of KH-550 hydrolyze, they not only condense with the silanol groups on the surface of the aerogel, but also crosslink between the aerogel and the magnesium phosphate crystal boundaries to form an ultra-thin organosilicon hydrophobic molecular film only a few nanometers thick; on the other hand, MPC itself has a dense and low porosity after hydration, making it difficult for water to penetrate. This triple protection of internal chemical anchoring + interface nano-hydrophobic film + dense inorganic crystals ensures that the putty remains free from bubbling and cracking even after continuous soaking in water for 48 hours.

[0074] (3) The core elements of combustion are the mass of the combustible material and the heat energy released. In the system of this invention, more than 98.5% of the mass is absolutely inorganic (MgO, phosphate, silica aerogel, glass microspheres, lithium magnesium silicate). The only organic carbon source comes from trace amounts of KH-550 molecular chain segments and 0.1~0.3 parts of HPMC. According to thermodynamic calculations, the tiny amount of heat released by these trace amounts of organic carbon during complete combustion is completely absorbed and blocked by the massive inorganic crystal network and the specific heat capacity of hollow microspheres and aerogels. In particular, when exposed to high-temperature flames, the MPC hydration product, magnesium potassium phosphate hexahydrate (MgKPO4·6H2O), will first undergo a thermal decomposition endothermic reaction, releasing a large amount of water vapor. This not only absorbs a large amount of latent heat, but also dilutes the oxygen concentration, achieving a continuous combustion time of 0s. Since no film-forming resins or additives containing VOCs, free formaldehyde, or benzene compounds are introduced, the formulation itself achieves a complete elimination of the GB18582-2020 environmental protection standard.

[0075] The resulting gel-based interior wall insulation putty can be well applied to interior wall insulation coating systems for green buildings and ultra-low energy consumption buildings.

[0076] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and comparative examples. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0077] <Raw materials>

[0078] Calcined magnesium oxide: Commercially available, calcined at 1600℃, with a specific surface area of ​​200m² / kg and an active content of 50%.

[0079] Hydrophobic silica aerogel powder: commercially available, porosity 92%, specific surface area 700m² / g, contact angle 155°, average particle size 25μm.

[0080] KH-550: γ-aminopropyltriethoxysilane, industrial grade.

[0081] Hollow glass microspheres: commercially available, true density 0.20 g / cm³, compressive strength 3 MPa.

[0082] Inorganic rheology modifier: Laponite RD type synthetic magnesium lithium silicate, commercially available.

[0083] Cellulose ether: HPMC, commercially available, viscosity 75000 mPa·s.

[0084] Other raw materials, such as potassium dihydrogen phosphate and borax, are all commercially available industrial-grade products.

[0085] <Examples, Comparative Examples, Formulations, and Preparation>

[0086] Examples 1-9

[0087] Table 1 lists the specific formulations (unit: parts by weight) of the thermal insulation putty dry powder of Examples 1 to 9 of the present invention. The modified aerogel in all examples was pre-modified at a weight ratio of aerogel to KH-550 of 100:3.5.

[0088] Table 1: Formulation Table for Examples 1-9 (Unit: Parts by Weight) Reburned magnesium oxide 20 25 30 15 22 28 18 26 24 Potassium dihydrogen phosphate 8 10 15 5 9 12 7 14 11 Borax (retarder) 1.0 1.5 2.5 0.5 1.2 2.0 0.8 2.2 1.8 Modified aerogel* 12 15 8 18 14 10 16 9 13 Hollow glass microspheres 15 18 25 10 16 22 12 24 20 Laponite rheology modifier 2 3 4 1 2.5 3.5 1.5 3 2 HPMC (cellulose ether) 0.2 0.1 0.3 0.1 0.2 0.1 0.3 0.2 0.1

[0089] *(Note: The weight ratio of aerogel to KH-550 in the modified aerogel is constant at 100:3.5)*

[0090] Comparative Examples 1-6

[0091] To highlight the inventive effect of this invention, the following comparative examples are provided, and the key points and purposes of the formula changes are detailed in Table 2.

[0092] Table 2: Formulation table of Comparative Examples 1-6 (Unit: parts by weight, with variable substitutions made for Comparative Example 2) Comparative Example 1 (Cement-based) Inorganic gel system replacement: Replacing the MPC system with ordinary silicate cement. 36.5 parts of 42.5 ordinary Portland cement, omitting re-burned magnesium oxide, potassium dihydrogen phosphate, and borax. The rest is the same as in Example 2. Comparative Example 2 (Unmodified) Eliminating interfacial silane bridging: using pure aerogel without KH-550 modification. Add 15 parts of the original hydrophobic aerogel directly. The rest is exactly the same as in Example 2. Comparative Example 3 (Traditional Adhesive Powder) Traditional polymer bonding approach: adding a large amount of VAE redispersible latex powder The base was the same as Comparative Example 2 (unmodified), with an additional 12 parts of VAE latex powder added to forcibly improve the bonding strength. Comparative Example 4 (Hydrophilic) Aerogel type replacement: Use hydrophilic aerogels instead of hydrophobic ones. Hydrophilic aerogel powder was used, and everything else was exactly the same as in Example 2. Comparative Example 5 (Breaking the Limit) Excessive aerogel addition: The proportion of aerogel exceeds the standard, leading to skeleton fracture. The amount of modified aerogel added was increased to 30 parts, and the amount of magnesium oxide was correspondingly reduced to 15 parts. The rest was the same as in Example 2. Comparative Example 6 (Organic Substrate) All-organic adhesive approach: using acrylic emulsion as a fully gelled base The dry powder contains only: 15 parts unmodified aerogel, 18 parts microbeads, and 25 parts heavy calcium carbonate powder. It is mixed with 40 parts acrylic emulsion and water.

[0093] Unified preparation method steps

[0094] The thermal insulation putty powders of Examples 1-9 and Comparative Examples 1-5 were all prepared using the following unified method (except for Comparative Example 6):

[0095] S1. Aerogel Modification Step: Dissolve the prescribed amount of KH-550 in anhydrous ethanol to prepare a 5% (w / w) modification solution. While stirring, uniformly spray this modification solution onto the hydrophobic silica aerogel powder using an atomization method. Then, transfer it to a closed reactor equipped with a stirrer and react at a constant temperature of 90°C for 1.5 hours. After the reaction is complete, remove the material and vacuum dry it at 120°C for 2 hours. Sift the dried material to obtain aminosilane-modified hydrophobic silica aerogel powder for later use. (If the comparative example does not include a KH-550 modification step, the original hydrophobic aerogel can be used directly).

[0096] S2. Basic dry mixing steps: According to the corresponding formula table, put the calcined magnesium oxide, potassium dihydrogen phosphate, retarder, inorganic rheology modifier and cellulose ether into the gravity-free mixer in sequence, set the speed to 70 r / min, mix for 12 minutes to obtain a uniform base material premix.

[0097] S3, Low-shear compounding step: Hollow glass microspheres and the aerogel powder obtained (or specified) in step S1 are added to the above base premix. A plowshare mixer is used, with a rotation speed set to 40 r / min, and low-shear mixing is performed for 20 minutes to obtain a uniformly mixed thermal insulation putty powder. Comparative Example 6 does not use this method; its dry powder contains only unmodified aerogel, microspheres, and heavy calcium carbonate powder.

[0098] S4. On-site mixing and specimen preparation: When using, weigh the dry powder and water at a mass ratio of 1:0.7. Slowly add the dry powder to the water while simultaneously stirring at a low speed of 400 rpm for 3 minutes using a mechanical mixer to form a uniform, particle-free paste-like putty. Comparative Example 6 uses 40 parts acrylic emulsion mixed with water as the mixing liquid. Apply the mixed putty to an asbestos-free fiber cement substrate according to standards such as JG / T298-2010. After curing under standard conditions for 7 days, conduct various performance tests.

[0099] <Performance Testing and Result Comparison Analysis>

[0100] The putty specimens prepared in Examples 1-9 and Comparative Examples 1-6 were subjected to system performance tests according to the following standards:

[0101] Bond strength and water resistance: tested according to JG / T298-2010 "Putty for Interior Building Use".

[0102] Thermal conductivity: Tested according to GB / T 10294-2008 "Determination of steady-state thermal resistance and related properties of thermal insulation materials - protective hot plate method".

[0103] Combustion performance: The furnace temperature rise, mass loss rate and continuous combustion time are tested according to GB / T5464-2010; the total calorific value is tested according to GB / T14402-2007; and the combustion performance level specified in GB / T8624-2012 is comprehensively evaluated.

[0104] Environmental performance: The content of VOC, formaldehyde, heavy metals, etc. was tested in accordance with GB18582-2020 "Limits of Hazardous Substances in Wall Coatings for Buildings".

[0105] Table 3 summarizes the comprehensive performance test results of the representative embodiments and comparative examples.

[0106] Table 3: Overall Performance Test Results of Examples and Comparative Examples Standard bond strength (MPa) 0.96 1.15 1.28 0.92 0.65 0.45 (Unacceptable) 0.95 1.10 1.35 ≥0.9 MPa Bond strength after immersion in water (MPa) 0.68 0.85 0.95 0.62 0.35 (Unacceptable) 0.15 (Unacceptable) 0.61 0.20 (Unacceptable) 0.75 ≥0.6 MPa Water resistance (immersion in water for 48 hours) No abnormalities No abnormalities No abnormalities No abnormalities Severe powder loss Bubbling, cracking, and peeling No abnormalities Severe powdering and peeling No abnormalities No bubbling, cracking, or powdering Thermal conductivity W / (m·K) 0.033 0.031 0.035 0.029 0.048 (Slightly high) 0.034 0.038 0.065 (Dead) 0.042 ≤0.035 Furnace temperature rise (°C) 12 10 8 15 8 10 45 (Unacceptable) 12 150 (Explosive) ≤25 ℃ Quality loss rate (%) 16 15 13 18 15 15 28 (Unqualified) 16 45 (Unacceptable) 10%~25% Burning duration (s) 0 0 0 0 0 0 12 (Failed) 0 45 (Unacceptable) 0 s Total calorific value (MJ / kg) 0.42 0.38 0.35 0.45 0.30 0.35 2.6 (Unacceptable) 0.38 6.5 (Unacceptable) ≤1.8 MJ / kg Combustion performance rating A1 A1 A1 A1 A1 A1 B1 (Unacceptable) A1 B2 (Unacceptable) A1 level VOCs and harmful substances Not detected Not detected Not detected Not detected Not detected Not detected VOCs detected Not detected VOCs / formaldehyde detected Not detected

[0107] *(Note: Table 3 omits Examples 5-9 and Comparative Example 5, which showed moderate performance. Examples 5-9 perfectly met all standards; Comparative Example 5, due to excessive aerogel, could not form a proper framework, resulting in a bond strength of only 0.2 MPa and rendering it unsuitable for construction.)*

[0108] <Core Mechanism Verification and Analysis of Examples and Comparative Examples>

[0109] (1) Verification of the breakthrough of the impossible triangle (comparison of Example 2 and Comparative Examples 2 and 3):

[0110] Comparing Example 2 of this invention (bonding strength 1.15 MPa, total calorific value 0.38 MJ / kg, A1 grade, zero VOC) with Comparative Example 2 (without KH-550 modified aerogel), since no PN chemical interface bridging was formed in Comparative Example 2, the inorganic slurry could not effectively encapsulate and bond the strongly hydrophobic aerogel particles, resulting in extremely poor cohesion. The standard bonding strength plummeted to 0.45 MPa, and it even collapsed directly after immersion in water (0.15 MPa), both failing to meet the standards.

[0111] To compensate for the lack of strength, Comparative Example 3 added 12 parts of traditional VAE latex powder to the material used in Comparative Example 2. Although its standard bond strength met the standard (0.95 MPa), the introduction of latex powder caused the total calorific value to soar to 2.6 MJ / kg, exceeding the A1 grade limit, the furnace temperature to rise by 45°C, and VOCs were detected. This caused its combustion performance to drop to B1 grade, completely negating the safety and environmental advantages of high-end interior wall materials.

[0112] In Embodiment 2 of this invention, an ultra-high bonding strength of 1.15 MPa and a total calorific value as low as 0.38 MJ / kg are achieved through an original phosphate-silane bridging method without the addition of any organic latex powder. This achieves a perfect fusion of high bonding strength and ultra-low calorific value, truly breaking through the industry's impossible triangle.

[0113] (2) Environmental erosion protection verification (comparison of Example 2 with Comparative Examples 1 and 4):

[0114] Comparative Example 1 used ordinary Portland cement (OPC) instead of the MPC system. Due to the strong alkalinity (pH>12.5) of OPC hydration chemically eroding the aerogel silicate skeleton, and the large amount of water required for cement hydration, some water was forced into the interface, causing the thermal conductivity to rise to 0.048 W / (m·K). Simultaneously, because there was no chemical bond between the cement and the aerogel, the bond strength after immersion in water was only 0.35 MPa, resulting in severe powdering and failing to meet standards. Furthermore, its thermal conductivity (0.048 W / (m·K)) also significantly increased due to the intrusion of some hydration water into the interface.

[0115] Comparative Example 4 used a hydrophilic aerogel. When water was added and mixed, its nanopores were instantly filled by free water, resulting in a complete loss of its heat preservation performance and a thermal conductivity that soared to 0.065 W / (m·K).

[0116] The MPC system (near-neutral reaction, rapid water fixation) combined with hydrophobic aerogel of the present invention perfectly solves this problem.

[0117] (3) Validation of formulation dosage limits (comparison of Examples 3 and 4 with Comparative Example 5):

[0118] Examples 3 and 4 verify that the present invention achieves excellent performance within the limits (upper and lower limits) of the claimed dosage ranges for potassium dihydrogen phosphate and modified aerogel. Comparative Example 5 increased the modified aerogel dosage to 30 parts (exceeding the upper limit of 18 parts). Due to the excessively large volume proportion of the extremely light aerogel, the system's powder bulk density was too low, the inorganic cementitious material could not form a continuous stress transfer network, and the bond strength was only 0.2 MPa, making it completely unusable for construction. This demonstrates the scientific validity and critical significance of the dosage range of the present invention.

[0119] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An aerogel interior wall insulation putty based on a magnesium phosphate-silane bridging interface, characterized in that, The thermal insulation putty is composed of dry powder components and water. The dry powder components, by weight, contain the following raw materials: Reburned magnesium oxide: 15-30 parts; Potassium dihydrogen phosphate: 5-15 parts; Retarder: 0.5~2.5 parts; Aminosilane-modified hydrophobic silica aerogel powder: 8-18 parts; Hollow glass microspheres: 10-25 parts; Inorganic rheology modifier: 1-4 parts; Cellulose ether: 0.1~0.3 parts.

2. The aerogel interior wall insulation putty according to claim 1, characterized in that, The recalcined magnesia is dead-burned magnesia obtained by calcination at 1500℃~1700℃, with a specific surface area of ​​150~250 m². 2 / kg, with an active content of 40%~60%.

3. The aerogel interior wall insulation putty according to claim 1, characterized in that, The aminosilane-modified hydrophobic silica aerogel powder is prepared by surface grafting modification of hydrophobic silica aerogel and γ-aminopropyltriethoxysilane (KH-550) at a weight ratio of 100:(2~5).

4. The aerogel interior wall insulation putty according to claim 2, characterized in that, The hydrophobic silica aerogel has a porosity ≥90% and a specific surface area ≥600 m². 2 / g, water contact angle ≥150°, particle size range 10~50μm.

5. The aerogel interior wall insulation putty according to claim 1, characterized in that, The retarder is one or a combination of sodium tetraborate, boric acid, or sucrose.

6. The aerogel interior wall insulation putty according to claim 1, characterized in that, The inorganic rheology modifier is synthetically produced lithium magnesium silicate or high-purity attapulgite.

7. The aerogel interior wall insulation putty according to claim 1, characterized in that, The true density of the hollow glass microspheres is 0.15~0.25 g / cm³. 3 Compressive strength ≥2MPa.

8. A method for preparing an aerogel interior wall insulation putty according to any one of claims 1-6, comprising the following steps: S1. Aerogel modification: KH-550 was dissolved in anhydrous ethanol to prepare a modification solution with a mass concentration of 5%. The solution was sprayed evenly on the surface of hydrophobic silica aerogel powder and reacted in a closed stirring at 80~100℃ for 1~2h. Then, it was vacuum dried at 110-130℃ to obtain aminosilane modified hydrophobic silica aerogel powder. S2. Dry powder mixing: Add the calcined magnesium oxide, potassium dihydrogen phosphate, retarder, inorganic rheology modifier and cellulose ether into a gravity-free mixer and mix at low speed for 10-15 minutes until uniform. S3, Lightweight aggregate composite: Add hollow glass microspheres and aminosilane-modified hydrophobic silica aerogel powder obtained in step S1 to the mixture in step S2, and mix with low shear force for 15-20 minutes to obtain thermal insulation putty dry powder. S4. Add water and mix: When using, add water at a mass ratio of dry powder to water of 1:(0.6~0.9), stir well and it is ready for application.

9. The aerogel interior wall insulation putty according to any one of claims 1-6, and its application in the interior wall insulation coating system of green buildings and ultra-low energy consumption buildings.