Water-based inorganic thermal insulation coating and preparation method thereof

Abstract

The invention discloses a water-based inorganic thermal insulation coating and a preparation method thereof, and belongs to the technical field of water-based coating production. The water-based inorganic thermal insulation coating comprises the following raw materials in percentage by mass: 42%-45% of silica sol, 20%-22% of gradient coated glass micropowder, 18%-20% of modified wollastonite powder, 4%-5% of titanium dioxide, 0.3%-0.5% of cellulose ether, 0.4%-0.6% of a dispersing agent, 0.2%-0.3% of a defoaming agent and the balance of deionized water. Wherein the gradient coated glass micropowder sequentially comprises hollow glass beads, a silane coupling agent activation layer, a silicon dioxide aerogel coating layer and an organic silicon resin flexible layer from inside to outside; the modified wollastonite powder is obtained by performing surface treatment on wollastonite powder through a silane solution. Through material design and process innovation, a solution with efficient heat preservation, high strength and long-term durability is provided for building energy saving in the alpine region.

Description

Technical Field

[0001] The present invention belongs to the technical field of water-based coating production, and in particular relates to a water-based inorganic thermal insulation coating and a preparation method thereof. Background Art

[0002] Driven by carbon neutrality policies, the market for building exterior insulation coatings has surged. Water-based inorganic coatings, due to their environmental friendliness (zero VOC), fire resistance (A1 grade), and strong weather resistance, have become a mainstream alternative to organic insulation materials. They are widely used in energy-saving renovations of high-rise buildings, industrial plants, and historic structures.

[0003] In existing technologies, inorganic coatings based on silica sol have the following technical contradictions: (1) Lightweight aggregates (such as glass microspheres) added to reduce thermal conductivity significantly reduce the coating's bond strength (≤0.5 MPa); (2) When the strength is increased by increasing the amount of wollastonite powder, the thermal conductivity rises to above 0.08 W / (m·K). More seriously, existing systems experience microcrack growth at low temperatures of -30°C (bond strength drops by more than 40% after five freeze-thaw cycles), which becomes a hidden defect in applications in high-altitude cold regions.

[0004] These issues make it difficult for existing products to simultaneously meet the requirements of JG / T 26-2022, "Inorganic Thermal Insulation Coatings for Building Exterior Walls," for thermal conductivity (≤0.065 W / (m·K)), bond strength (≥1.0 MPa), and frost resistance (≤20% strength loss after 10 freeze-thaw cycles). Developing new composite systems that combine low-temperature stability with mechanical properties has become a key technical challenge in the industry. Summary of the Invention

[0005] The present invention aims to improve the low-temperature stability and mechanical properties of a silica sol-based inorganic coating by adding fillers such as gradient-coated glass micropowder and modified wollastonite powder to the coating. To this end, the present invention provides a water-based inorganic thermal insulation coating and a preparation method thereof.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A water-based inorganic thermal insulation coating, comprising the following raw materials in percentage by weight:

[0008] Silica sol 42% to 45%;

[0009] Gradient coated glass powder 20% to 22%;

[0010] Modified wollastonite powder 18% to 20%;

[0011] Titanium dioxide 4% to 5%;

[0012] Cellulose ether 0.3% to 0.5%;

[0013] Dispersant 0.4% to 0.6%;

[0014] Defoaming agent 0.2% to 0.3%;

[0015] The balance is deionized water;

[0016] The gradient coated glass micropowder comprises, from the inside to the outside, hollow glass microbeads, a silane coupling agent activation layer, a silica aerogel coating layer and a silicone resin flexible layer;

[0017] The modified wollastonite powder is obtained by surface treatment of wollastonite powder with a silane solution.

[0018] Furthermore, the solid content of the silica sol is 50%; the titanium dioxide is R-996 titanium dioxide; the viscosity of the cellulose ether is 20,000 mPa·s; the dispersant is dispersant BYK-190; and the defoamer is defoamer BYK-028.

[0019] Furthermore, the gradient coated glass powder is prepared by the following steps:

[0020] A1. Add KH-550 and citric acid to anhydrous ethanol and stir magnetically for 20 to 30 minutes to obtain an activation solution. Immerse hollow glass microspheres in the activation solution and ultrasonically treat for 20 to 30 minutes. Filter and dry the mixture to obtain activated microspheres.

[0021] A2. Silica aerogel powder was added to anhydrous ethanol and sheared for 15-20 minutes to obtain an aerogel dispersion. The activated microbeads were placed in a fluidized bed coating machine with the inlet air temperature set to 40°C. The aerogel dispersion was sprayed in an atomized manner. The aerogel dispersion was sprayed completely within 60 minutes. After completion, the aerogel dispersion was dried with hot air to obtain a microbead-aerogel composite.

[0022] A3. Dissolve the organosilicon resin DC-3055 in butanone and stir magnetically for 10 to 30 minutes to obtain a resin solution. Load the microbead-aerogel complex into a fluidized bed with the inlet air temperature set at 40 to 45°C. Atomize and spray the resin solution into the fluidized bed. Maintain fluidization for 30 minutes after spraying. After completion, dry the mixture with hot air to obtain a gradient-coated glass powder.

[0023] Furthermore, the usage ratio of KH-550, citric acid, anhydrous ethanol, and hollow glass microspheres described in A1 is 2kg:0.5-1.0kg:98kg:10kg.

[0024] Furthermore, the usage ratio of the silica aerogel powder, anhydrous ethanol, and activated microbeads in A2 is 2kg:10kg:10kg.

[0025] Furthermore, the usage ratio of the organosilicon resin DC-3055, butanone, and microbead-aerogel composite in A3 is 1 kg:19 kg:10 kg.

[0026] Furthermore, the particle size of the hollow glass microspheres is 50±5 μm; and the particle size of the silica aerogel powder is 100 nm.

[0027] Furthermore, the modified wollastonite powder is prepared by the following steps:

[0028] Take KH-560 and add it to anhydrous ethanol. Stir it magnetically for 20 to 30 minutes to obtain a silane solution. Immerse the wollastonite powder in the silane solution and stir it mechanically for 10 to 20 minutes. Then, treat it ultrasonically for 30 minutes. Then, filter it, dry it, and pass it through an 800-mesh sieve to obtain modified wollastonite powder.

[0029] Furthermore, the usage ratio of KH-560, anhydrous ethanol and wollastonite powder is 0.2-0.5 kg: 2 kg: 10 kg.

[0030] Furthermore, the preparation method of the water-based inorganic thermal insulation coating comprises the following steps:

[0031] Weigh each raw material according to mass percentage, add cellulose ether, dispersant and defoaming agent into deionized water with stirring, stir at 400 rpm for 20 to 30 minutes, then add silica sol thereto with stirring, stir at 800 rpm for 10 to 20 minutes, after completion, add modified wollastonite powder and titanium dioxide thereto in sequence, stir at 400 rpm for 30 minutes, then add gradient-coated glass micropowder thereto with stirring, stir at 400 rpm for 5 to 10 minutes, after completion, obtain a water-based inorganic thermal insulation coating.

[0032] The beneficial effects of the present invention compared to the prior art are as follows:

[0033] (1) Synchronous optimization of thermal conductivity and strength performance: The present invention solves the contradiction between the addition of lightweight aggregate and the improvement of strength by adding self-made filler gradient-coated glass powder (aerogel layer reduces thermal conductivity, activation layer increases adhesion) and modified wollastonite powder to the water-based inorganic thermal insulation coating. The thermal conductivity coefficient (≤0.063W / (m·K)) and initial bonding strength (≥1.28MPa) of Examples 7 to 9 are better than the standard.

[0034] (2) Significantly improved low-temperature stability: The silicone resin flexible layer of the self-made filler gradient-coated glass micropowder of the present invention effectively inhibits the propagation of microcracks during freeze-thaw cycles at -30°C. The strength loss rate of Examples 7 to 9 (≤11.7%) is reduced by more than 50% compared with Comparative Examples 4 to 7 (≥18.4%).

[0035] (3) Collaborative innovation to overcome industry challenges: The synergistic effect of the gradient coating structure of the gradient coated glass powder and the surface modified filler of the modified wollastonite powder achieves for the first time the simultaneous compliance of the three key indicators of thermal conductivity, bonding strength and frost resistance in the JG / T 26-2022 standard (such as 0.061 W / (m·K), 1.38 MPa, and 11.6% in Example 9).

[0036] In summary, the present invention provides a solution for building energy conservation in high-altitude and cold regions that combines efficient thermal insulation, high strength and long-term durability through material design and process innovation. DETAILED DESCRIPTION

[0037] Below in conjunction with the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, it is obvious that described embodiment is only a part of embodiment of the present invention, rather than whole embodiment. Based on the embodiment in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise all fall within the scope of protection of the present invention. Meanwhile, raw materials, reagents or devices used in the following examples, unless otherwise specified, can be obtained from conventional commercial channels, or can be obtained by existing known methods.

[0038] Example 1

[0039] Preparation of gradient coated glass powder:

[0040] A1. Surface activation of silane coupling agent (construction of silane coupling agent activation layer):

[0041] (1) Preparation of activation solution: Add 2 kg of KH-550 and 0.5 kg of citric acid to 98 kg of anhydrous ethanol and stir magnetically for 20 min to prepare activation solution;

[0042] (2) Activation treatment: 10 kg of hollow glass microspheres (3M K46, particle size 50 ± 5 μm) were immersed in the above activation solution and ultrasonically treated (40 kHz, 300 W) for 20 min. After filtration, the solid components were collected and dried at 80 °C for 2 h to obtain activated microspheres (Si-O-Si bonds formed on the surface).

[0043] A2. Silica aerogel coating (constructing a silica aerogel coating layer):

[0044] (1) Aerogel dispersion: 2 kg of silica aerogel powder (particle size 100 nm, purchased from Nanotech) was added to 10 kg of anhydrous ethanol and sheared (5000 rpm) for 15 min to obtain an aerogel dispersion.

[0045] (2) Mixed coating: 10 kg of activated microbeads were put into a fluidized bed coating machine, the air inlet temperature was set to 40 °C, and the aerogel dispersion was sprayed at a spray rate of 200 mL / min (nozzle diameter 0.8 mm), and the fluidization wind speed was set to 0.8 m 3 / h, the aerogel dispersion was sprayed within 60 min, and after completion, it was placed in a hot air drying at 100 ° C for 1 h to obtain a microbead-aerogel composite;

[0046] A3. Silicone resin flexible coating (construction of silicone resin flexible layer):

[0047] (1) Resin dilution: Dissolve 1 kg of organosilicon resin (DC-3055) in 19 kg of butanone and stir magnetically for 10 min to obtain a resin solution;

[0048] (2) Gradient coating: 10 kg of microbead-aerogel composite was loaded into the fluidized bed, the inlet air temperature was set to 40 °C, the resin solution was atomized and sprayed at a rate of 150 mL / min (nozzle diameter 1.0 mm), and the fluidization wind speed was set to 0.5 m 3 / h, maintain fluidization for 30 minutes after spraying, and then place it in 80℃ hot air drying for 2 hours to obtain gradient coated glass powder.

[0049] Example 2

[0050] Preparation of gradient coated glass powder:

[0051] A1. Surface activation of silane coupling agent (construction of silane coupling agent activation layer):

[0052] (1) Preparation of activation solution: 2 kg of KH-550 and 1.0 kg of citric acid were added to 98 kg of anhydrous ethanol and magnetically stirred for 30 min to prepare an activation solution;

[0053] (2) Activation treatment: 10 kg of hollow glass microspheres (3M K46, particle size 50 ± 5 μm) were immersed in the above activation solution and ultrasonically treated (40 kHz, 300 W) for 30 min. After filtration, the solid components were collected and dried at 80 °C for 2 h to obtain activated microspheres (Si-O-Si bonds formed on the surface).

[0054] A2. Silica aerogel coating (constructing a silica aerogel coating layer):

[0055] (1) Aerogel dispersion: 2 kg of silica aerogel powder (particle size 100 nm, purchased from Nanotech) was added to 10 kg of anhydrous ethanol and sheared (5000 rpm) for 20 min to obtain an aerogel dispersion.

[0056] (2) Mixed coating: 10 kg of activated microbeads were put into a fluidized bed coating machine, the air inlet temperature was set to 40 °C, and the aerogel dispersion was sprayed at a spray rate of 200 mL / min (nozzle diameter 0.8 mm), and the fluidization wind speed was set to 0.8 m 3 / h, and the aerogel dispersion was sprayed within 60 min. After completion, it was placed in a hot air drying at 100 ° C for 2 h to obtain a microbead-aerogel composite;

[0057] A3. Silicone resin flexible coating (construction of silicone resin flexible layer):

[0058] (1) Resin dilution: Dissolve 1 kg of organosilicon resin (DC-3055) in 19 kg of butanone and stir magnetically for 30 min to obtain a resin solution;

[0059] (2) Gradient coating: 10 kg of microbead-aerogel composite was loaded into the fluidized bed, the inlet air temperature was set to 45 °C, the resin solution was atomized and sprayed at a rate of 150 mL / min (nozzle diameter 1.0 mm), and the fluidization wind speed was set to 0.5 m 3 / h, maintain fluidization for 30 minutes after spraying, and then place it in 80℃ hot air drying for 4 hours to obtain gradient coated glass powder.

[0060] Example 3

[0061] Preparation of gradient coated glass powder:

[0062] A1. Surface activation of silane coupling agent (construction of silane coupling agent activation layer):

[0063] (1) Preparation of activation solution: 2 kg of KH-550 and 0.8 kg of citric acid were added to 98 kg of anhydrous ethanol and magnetically stirred for 30 min to prepare the activation solution;

[0064] (2) Activation treatment: 10 kg of hollow glass microspheres (3M K46, particle size 50 ± 5 μm) were immersed in the above activation solution and ultrasonically treated (40 kHz, 300 W) for 30 min. After filtration, the solid components were collected and dried at 80 °C for 2 h to obtain activated microspheres (Si-O-Si bonds formed on the surface).

[0065] A2. Silica aerogel coating (constructing a silica aerogel coating layer):

[0066] (1) Aerogel dispersion: 2 kg of silica aerogel powder (particle size 100 nm, purchased from Nanotech) was added to 10 kg of anhydrous ethanol and sheared (5000 rpm) for 20 min to obtain an aerogel dispersion.

[0067] (2) Mixed coating: 10 kg of activated microbeads were put into a fluidized bed coating machine, the air inlet temperature was set to 40 °C, and the aerogel dispersion was sprayed at a spray rate of 200 mL / min (nozzle diameter 0.8 mm), and the fluidization wind speed was set to 0.8 m 3 / h, and the aerogel dispersion was sprayed within 60 min. After completion, it was placed in a hot air drying at 100 ° C for 2 h to obtain a microbead-aerogel composite;

[0068] A3. Silicone resin flexible coating (construction of silicone resin flexible layer):

[0069] (1) Resin dilution: Dissolve 1 kg of organosilicon resin (DC-3055) in 19 kg of butanone and stir magnetically for 30 min to obtain a resin solution;

[0070] (2) Gradient coating: 10 kg of microbead-aerogel composite was loaded into the fluidized bed, the inlet air temperature was set to 45 °C, the resin solution was atomized and sprayed at a rate of 150 mL / min (nozzle diameter 1.0 mm), and the fluidization wind speed was set to 0.5 m 3 / h, maintain fluidization for 30 minutes after spraying, and then place it in 80℃ hot air drying for 4 hours to obtain gradient coated glass powder.

[0071] Comparative Example 1

[0072] Comparative Example 1 is the control group of Example 3, and Comparative Example 1 is the raw material hollow glass microspheres of Example 3 (3M K46, particle size 50±5 μm).

[0073] Comparative Example 2

[0074] Comparative Example 2 is the control group of Example 3, except that the silica aerogel coating process A2 and the flexible silicone resin coating process A3 in Example 3 are removed. The remaining raw materials, raw material amounts, and preparation steps are consistent with those in Example 3, as follows:

[0075] Preparation of activated microbeads:

[0076] A1. Surface activation of silane coupling agent (construction of silane coupling agent activation layer):

[0077] (1) Preparation of activation solution: 2 kg of KH-550 and 0.8 kg of citric acid were added to 98 kg of anhydrous ethanol and magnetically stirred for 30 min to prepare the activation solution;

[0078] (2) Activation treatment: 10 kg of hollow glass microspheres (3M K46, particle size 50 ± 5 μm) were immersed in the above activation solution and ultrasonically treated (40 kHz, 300 W) for 30 min. After filtration, the solid components were collected and dried at 80 °C for 2 h to obtain activated microspheres (Si-O-Si bonds formed on the surface).

[0079] Comparative Example 3

[0080] Comparative Example 3 is the control group of Example 3. The flexible coating process of the A3 silicone resin in Example 3 is removed. The remaining raw materials, raw material amounts and preparation steps are the same as those in Example 3, as follows:

[0081] Preparation of microbead-aerogel composites:

[0082] A1. Surface activation of silane coupling agent (construction of silane coupling agent activation layer):

[0083] (1) Preparation of activation solution: 2 kg of KH-550 and 0.8 kg of citric acid were added to 98 kg of anhydrous ethanol and magnetically stirred for 30 min to prepare the activation solution;

[0084] (2) Activation treatment: 10 kg of hollow glass microspheres (3M K46, particle size 50 ± 5 μm) were immersed in the above activation solution and ultrasonically treated (40 kHz, 300 W) for 30 min. After filtration, the solid components were collected and dried at 80 °C for 2 h to obtain activated microspheres (Si-O-Si bonds formed on the surface).

[0085] A2. Silica aerogel coating (constructing a silica aerogel coating layer):

[0086] (1) Aerogel dispersion: 2 kg of silica aerogel powder (particle size 100 nm, purchased from Nanotech) was added to 10 kg of anhydrous ethanol and sheared (5000 rpm) for 20 min to obtain an aerogel dispersion.

[0087] (2) Mixed coating: 10 kg of activated microbeads were put into a fluidized bed coating machine, the air inlet temperature was set to 40 °C, and the aerogel dispersion was sprayed at a spray rate of 200 mL / min (nozzle diameter 0.8 mm), and the fluidization wind speed was set to 0.8 m 3 / h, and the aerogel dispersion was sprayed within 60 min. After completion, it was placed in a hot air drying at 100 ° C for 2 h to obtain a microbead-aerogel composite.

[0088] Example 4

[0089] Preparation of modified wollastonite powder:

[0090] B1. Prepare silane solution: add 0.2 kg of KH-560 to 2 kg of anhydrous ethanol and stir magnetically (500 rpm) for 20 min until the solution is homogeneous and transparent (KH-560 hydrolyzes to form silanols, which enhances activity) to obtain a silane solution;

[0091] B2. Surface modification: 10 kg of wollastonite powder (1250 mesh) was immersed in the silane solution and mechanically stirred (200 rpm) for 10 min for preliminary wetting. The wollastonite was then ultrasonically treated (40 kHz, 300 W) for 30 min to uniformly coat the silane on the flaky surface (ultrasonic energy promotes condensation of silane with surface hydroxyl groups). The excess solution was then removed by filtration, and the solid was collected and dried at 80° C. for 2 h to completely solidify the silane layer. The solid was then sieved through an 800-mesh sieve to remove agglomerated particles produced during the drying process to obtain modified wollastonite powder.

[0092] Example 5

[0093] Preparation of modified wollastonite powder:

[0094] B1. Prepare silane solution: add 0.5 kg of KH-560 to 2 kg of anhydrous ethanol and stir magnetically (500 rpm) for 30 min until the solution is homogeneous and transparent (KH-560 hydrolyzes to form silanols, which enhances activity) to obtain a silane solution;

[0095] B2. Surface modification: 10 kg of wollastonite powder (1250 mesh) was immersed in the silane solution and mechanically stirred (200 rpm) for 20 min for preliminary wetting. The wollastonite was then ultrasonically treated (40 kHz, 300 W) for 30 min to uniformly coat the silane on the flaky surface (ultrasonic energy promotes condensation of silane with surface hydroxyl groups). The excess solution was then removed by filtration, and the solid was collected and dried at 80° C. for 4 h to completely solidify the silane layer. The solid was then sieved through an 800-mesh sieve to remove agglomerated particles produced during the drying process to obtain modified wollastonite powder.

[0096] Example 6

[0097] Preparation of modified wollastonite powder:

[0098] B1. Prepare silane solution: add 0.4 kg of KH-560 to 2 kg of anhydrous ethanol and stir magnetically (500 rpm) for 30 min until the solution is homogeneous and transparent (KH-560 hydrolyzes to form silanols, which enhances activity) to obtain a silane solution;

[0099] B2. Surface modification: 10 kg of wollastonite powder (1250 mesh) was immersed in the silane solution and mechanically stirred (200 rpm) for 20 min for preliminary wetting. The wollastonite was then ultrasonically treated (40 kHz, 300 W) for 30 min to uniformly coat the silane on the flaky surface (ultrasonic energy promotes condensation of silane with surface hydroxyl groups). The excess solution was then removed by filtration, and the solid was collected and dried at 80° C. for 4 h to completely solidify the silane layer. The solid was then sieved through an 800-mesh sieve to remove agglomerated particles produced during the drying process to obtain modified wollastonite powder.

[0100] Example 7

[0101] Preparation of water-based inorganic thermal insulation coating:

[0102] First, the water-based inorganic thermal insulation coating includes the following raw materials in percentage by weight:

[0103] Silica sol (solid content 50%) 42%;

[0104] 20% of the gradient-coated glass powder prepared in Example 1;

[0105] 18% of the modified wollastonite powder prepared in Example 4;

[0106] Titanium dioxide (R-996) 4%;

[0107] Cellulose ether (HPMC 20,000 viscosity) 0.3%;

[0108] Dispersant (BYK-190) 0.4%;

[0109] Defoamer (BYK-028) 0.2%;

[0110] The balance was deionized water.

[0111] Then, the preparation method of the above-mentioned water-based inorganic thermal insulation coating comprises the following steps:

[0112] Weigh each raw material according to mass percentage, add cellulose ether, dispersant and defoamer to deionized water with stirring, stir at 400 rpm for 20 minutes, then add silica sol thereto with stirring, stir at 800 rpm for 10 minutes, after completion, add the modified wollastonite powder and titanium dioxide prepared in Example 4 in sequence, stir at 400 rpm for 30 minutes, then add the gradient-coated glass micropowder prepared in Example 1 with stirring, stir at 400 rpm for 5 minutes, after completion, obtain a water-based inorganic thermal insulation coating.

[0113] Example 8

[0114] Preparation of water-based inorganic thermal insulation coating:

[0115] First, the water-based inorganic thermal insulation coating includes the following raw materials in percentage by weight:

[0116] Silica sol (solid content 50%) 44%;

[0117] Gradient coated glass powder prepared in Example 2 22%;

[0118] 20% of the modified wollastonite powder prepared in Example 5;

[0119] Titanium dioxide (R-996) 4%;

[0120] Cellulose ether (HPMC 20,000 viscosity) 0.4%;

[0121] Dispersant (BYK-190) 0.6%;

[0122] Defoamer (BYK-028) 0.3%;

[0123] The balance was deionized water.

[0124] Then, the preparation method of the above-mentioned water-based inorganic thermal insulation coating comprises the following steps:

[0125] Weigh each raw material according to mass percentage, add cellulose ether, dispersant and defoamer to deionized water with stirring, stir at 400 rpm for 30 minutes, then add silica sol thereto with stirring, stir at 800 rpm for 20 minutes, after completion, add the modified wollastonite powder and titanium dioxide prepared in Example 5 in sequence, stir at 400 rpm for 30 minutes, then add the gradient-coated glass powder prepared in Example 2 with stirring, stir at 400 rpm for 10 minutes, after completion, obtain a water-based inorganic thermal insulation coating.

[0126] Example 9

[0127] Preparation of water-based inorganic thermal insulation coating:

[0128] First, the water-based inorganic thermal insulation coating includes the following raw materials in percentage by weight:

[0129] Silica sol (solid content 50%) 45%;

[0130] Gradient coated glass powder prepared in Example 3 22%;

[0131] 20% of the modified wollastonite powder prepared in Example 6;

[0132] Titanium dioxide (R-996) 5%;

[0133] Cellulose ether (HPMC 20,000 viscosity) 0.5%;

[0134] Dispersant (BYK-190) 0.6%;

[0135] Defoamer (BYK-028) 0.3%;

[0136] The balance was deionized water.

[0137] Then, the preparation method of the above-mentioned water-based inorganic thermal insulation coating comprises the following steps:

[0138] Weigh each raw material according to mass percentage, add cellulose ether, dispersant and defoamer to deionized water with stirring, stir at 400 rpm for 30 minutes, then add silica sol thereto with stirring, stir at 800 rpm for 20 minutes, after completion, add the modified wollastonite powder and titanium dioxide prepared in Example 6 in sequence, stir at 400 rpm for 30 minutes, then add the gradient-coated glass powder prepared in Example 3 with stirring, stir at 400 rpm for 10 minutes, after completion, obtain a water-based inorganic thermal insulation coating.

[0139] Comparative Example 4

[0140] Comparative Example 4 is the control group of Example 9. The gradient-coated glass powder prepared in Example 3 in Example 9 is replaced with the hollow glass microspheres of Comparative Example 1. The remaining raw materials, raw material amounts and preparation steps remain the same as in Example 9, and finally a water-based inorganic thermal insulation coating is obtained.

[0141] Comparative Example 5

[0142] Comparative Example 5 is the control group of Example 9, in which the gradient-coated glass micropowder prepared in Example 3 of Example 9 is replaced with the activated microbeads of Comparative Example 2, and the remaining raw materials, raw material amounts and preparation steps remain the same as in Example 9, and finally a water-based inorganic thermal insulation coating is obtained.

[0143] Comparative Example 6

[0144] Comparative Example 6 is the control group of Example 9. The gradient-coated glass powder prepared in Example 3 in Example 9 is replaced by the microbead-aerogel complex of Comparative Example 3. The remaining raw materials, raw material amounts and preparation steps remain the same as in Example 9, and finally a water-based inorganic thermal insulation coating is obtained.

[0145] Comparative Example 7

[0146] Comparative Example 7 is the control group of Example 9. The modified wollastonite powder prepared in Example 6 in Example 9 is replaced by the raw wollastonite powder (1250 mesh) of Example 6. The remaining raw materials, raw material amounts and preparation steps remain the same as in Example 9, and finally a water-based inorganic thermal insulation coating is obtained.

[0147] The performance test of the water-based inorganic thermal insulation coatings prepared in Examples 7 to 9 and Comparative Examples 4 to 7 was carried out. The performance test process is as follows, and the test results are shown in Table 1:

[0148] 1. Thermal conductivity test:

[0149] (1) Test equipment: Thermal conductivity meter (guarded hot plate method, accuracy ±0.001 W / (m·K)).

[0150] (2) Test steps:

[0151] a. Specimen preparation: Apply the coating to a polytetrafluoroethylene plate with a wet film thickness of 2.0 mm, cure at room temperature (23 ± 2 ° C) for 7 days, and cut into 300 × 300 × 10 mm 3 Flat specimen (thickness error ±0.1mm).

[0152] b. Test conditions: cold plate temperature 10°C; hot plate temperature 30°C; constant temperature difference 20°C.

[0153] c. Measurement Procedure: Place the prepared specimen between a hot plate and a cold plate, applying a pressure of 5 kPa to ensure close contact. After the heat flux stabilizes (≥30 min), record the heat flux density Q and the temperature difference ΔT.

[0154] d. Calculation: λ = (Q·d) / (A·ΔT);

[0155] Where, λ is the thermal conductivity (W / (m·K)); Q is the heat flux (W); d is the specimen thickness (m); A is the specimen area (m 2 ); ΔT is the temperature difference (K).

[0156] 2. Bond strength test (initial / after freeze-thaw):

[0157] (1) Testing equipment: universal material testing machine (accuracy level 0.5), freeze-thaw test chamber (-30℃±2℃).

[0158] (2) Specimen preparation:

[0159] Base material: cement mortar board (70×70×20mm 3 , compressive strength ≥40MPa);

[0160] Coating: scrape the coating to a wet film thickness of 1.5mm and cure at room temperature for 28 days;

[0161] Bonding test piece: 40×40mm with epoxy resin 2 Steel pulling head.

[0162] (3) Test steps:

[0163] A. Initial strength test: The prepared specimens were cured in a temperature (23 ± 2 ° C) and humidity (50 ± 5%) environment for 7 days, and vertically stretched at a rate of (5 ± 0.5) mm / min. The maximum breaking load F was recorded. max .

[0164] Calculation: σ initial = F max / A 粘结 Among them, A 粘结 For bonding area (1600mm 2 ).

[0165] B. Strength test after freeze-thaw cycle: The prepared specimens were immersed in (23±2)℃ water for 48h until saturated, and then moved into a freeze-thaw chamber for freeze-thaw treatment. In the freezing stage, the specimens were maintained at -30±2℃ for 4h; in the thawing stage, the specimens were immersed in 23±2℃ water for 4h (the water surface was 20mm above the specimen). After 10 freeze-thaw cycles, the surface water stains were wiped off, and the specimens were allowed to return to room temperature for 24h. The freeze-thaw strength σ was tested in the same way. 冻融 .

[0166] C. Calculation of strength loss rate: Loss rate = (σ 初始 -σ 冻融 )×100% / σ 初始 .

[0167] Table 1 Test results

[0168]

[0169] According to the data analysis in Table 1:

[0170] (1) Solving the contradiction between thermal conductivity and bonding strength (based on the data of Examples 7-9 vs. Comparative Examples 4-6). The core contradiction of the prior art is that adding lightweight aggregates (such as glass microspheres) can reduce thermal conductivity, but at the expense of bonding strength (≤0.5 MPa). The present invention solves this problem by gradient coating glass micropowder (three-layer structure: silane coupling agent activation layer, silica aerogel coating layer, silicone resin flexible layer). The specific analysis is as follows:

[0171] A. The thermal conductivity is significantly reduced (meeting the standard of ≤0.065W / (m·K)): The thermal conductivity of Examples 7 to 9 are 0.063, 0.062, and 0.061W / (m·K), respectively, all below the standard limit (0.065W / (m·K)). This is due to the silica aerogel coating (nano-scale low thermal conductivity material), whose thermal insulation performance is efficiently exerted in the gradient structure. Comparative verification: Comparative Example 4 (only uncoated hollow glass microspheres): thermal conductivity is 0.079W / (m·K), far exceeding the standard, proving that the untreated aggregate has insufficient thermal insulation; Comparative Example 6 (no silicone resin layer, only aerogel coating): thermal conductivity is 0.065W / (m·K), indicating that the aerogel layer is the key to reducing the thermal conductivity, but the lack of a flexible layer leads to other performance defects.

[0172] B. Significantly Improved Bond Strength (Meets ≥1.0 MPa Standard): The initial bond strength of Examples 7-9 reached 1.28-1.38 MPa, far exceeding the standard (1.0 MPa). This is attributed to the silane coupling agent activation layer of the gradient-coated glass micropowder, which enhances the chemical bonding (Si-O-Si bond) with the silica sol matrix. Simultaneously, the modified wollastonite powder (treated with KH-560 silane) forms Si-O-Ca covalent bonds, improving the interfacial strength between the filler and the matrix. Comparative Verification: Comparative Example 4 (uncoated hollow glass microspheres): The initial strength was only 0.42 MPa, demonstrating that the untreated aggregate severely weakens the bonding properties. Comparative Example 5 (silane activation layer only): initial strength 0.68 MPa, still below the standard, indicating that single-layer activation is not enough to solve the strength problem; Comparative Example 7 (unmodified wollastonite powder): initial strength 0.87 MPa, although better than Comparative Examples 4-5, but lower than 1.38 MPa of Example 9, highlighting the necessity of wollastonite powder modification.

[0173] (2) Breaking through the bottleneck of low-temperature frost resistance (based on the data of Examples 7 to 9 vs. Comparative Examples 4 to 7), the prior art significantly reduces the bonding strength after freeze-thaw cycles at -30°C, while the present invention synergistically improves low-temperature stability through the flexible silicone resin layer and modified wollastonite powder. The specific analysis is as follows:

[0174] A. Extremely low strength loss after freeze-thaw (meets the ≤20% standard): Examples 7-9 exhibited strength loss rates of only 11.3% to 11.7%, far below the standard (20%). The flexible silicone resin layer (e.g., DC-3055) buffers thermal stress at low temperatures and inhibits microcrack propagation, while the modified wollastonite powder strengthens the coating's cohesion. Comparative verification: Comparative Example 4 (uncoated hollow glass microspheres): a loss rate of 50.0%, highlighting the susceptibility of untreated aggregate to cracking during freeze-thaw. Comparative Example 6 (without a silicone resin layer): a loss rate of 24.7%, which, while better than Comparative Examples 4-5, still exceeds the standard, demonstrating the crucial importance of the flexible layer for frost resistance. Comparative Example 7 (unmodified wollastonite): a loss rate of 18.4%, close to the standard but higher than the 11.6% of Example 9, indicating that the modification enhances the low-temperature interfacial stability of the wollastonite powder.

[0175] (3) Verification of synergistic effect (based on the data of Comparative Example 6 vs. Example 9): The synergistic effect of the three-layer structure of the gradient-coated glass powder and the modified wollastonite powder is the core innovation of the present invention. The specific analysis is as follows:

[0176] Comparative Example 6 (aerogel coating only without flexible layer): The thermal conductivity of 0.065W / (m·K) is qualified, but the initial strength (0.97MPa) and freeze-thaw loss rate (24.7%) do not meet the standards, proving that a single aerogel layer cannot take into account both performance; Example 9 (complete gradient coating + modified wollastonite powder): thermal conductivity of 0.061W / (m·K), initial strength of 1.38MPa, loss rate of 11.6%, all of which meet the standards at the same time, highlighting that: the aerogel layer ensures thermal insulation, the flexible layer improves frost resistance, and the modified wollastonite powder enhances mechanical strength.

[0177] It should be noted that, in this document, terms such as "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0178] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may 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. A water-based inorganic thermal insulation coating, characterized in that: Including the following raw materials by mass percentage: Silica sol 42% to 45%; Gradient coated glass powder 20% to 22%; Modified wollastonite powder 18% to 20%; Titanium dioxide 4% to 5%; Cellulose ether 0.3% to 0.5%; Dispersant 0.4% to 0.6%; Defoaming agent 0.2% to 0.3%; The balance is deionized water; The gradient coated glass micropowder comprises, from the inside to the outside, hollow glass microbeads, a silane coupling agent activation layer, a silica aerogel coating layer and a silicone resin flexible layer; The modified wollastonite powder is obtained by surface treatment of wollastonite powder with a silane solution.

2. A water-based inorganic thermal insulation coating according to claim 1, characterized in that: The solid content of the silica sol is 50%; the titanium dioxide is R-996 titanium dioxide; the viscosity of the cellulose ether is 20,000 mPa·s; the dispersant is dispersant BYK-190; and the defoamer is defoamer BYK-028.

3. A water-based inorganic thermal insulation coating according to claim 1, characterized in that: The gradient coated glass powder is prepared by the following steps: A1. Add KH-550 and citric acid to anhydrous ethanol and stir magnetically for 20 to 30 minutes to obtain an activation solution. Immerse hollow glass microspheres in the activation solution and ultrasonically treat for 20 to 30 minutes. Filter and dry the mixture to obtain activated microspheres. A2. Silica aerogel powder was added to anhydrous ethanol and sheared for 15-20 minutes to obtain an aerogel dispersion. The activated microbeads were placed in a fluidized bed coating machine with the inlet air temperature set to 40°C. The aerogel dispersion was sprayed in an atomized manner. The aerogel dispersion was sprayed completely within 60 minutes. After completion, the aerogel dispersion was dried with hot air to obtain a microbead-aerogel composite. A3. Dissolve the organosilicon resin DC-3055 in butanone and stir magnetically for 10 to 30 minutes to obtain a resin solution. Load the microbead-aerogel complex into a fluidized bed with the inlet air temperature set at 40 to 45°C. Atomize and spray the resin solution into the fluidized bed. Maintain fluidization for 30 minutes after spraying. After completion, dry the mixture with hot air to obtain a gradient-coated glass powder.

4. A water-based inorganic thermal insulation coating according to claim 3, characterized in that: The usage ratio of KH-550, citric acid, anhydrous ethanol and hollow glass microspheres described in A1 is 2kg:0.5-1.0kg:98kg:10kg.

5. A water-based inorganic thermal insulation coating according to claim 3, characterized in that: The usage ratio of the silica aerogel powder, anhydrous ethanol, and activated microbeads described in A2 is 2kg:10kg:10kg.

6. The water-based inorganic thermal insulation coating according to claim 3, characterized in that: The usage ratio of the organosilicon resin DC-3055, butanone, and microbead-aerogel composite in A3 is 1 kg:19 kg:10 kg.

7. The water-based inorganic thermal insulation coating according to claim 3, characterized in that: The particle size of the hollow glass microspheres is 50±5 μm; the particle size of the silica aerogel powder is 100 nm.

8. The water-based inorganic thermal insulation coating according to claim 1, characterized in that: The modified wollastonite powder is prepared by the following steps: Take KH-560 and add it to anhydrous ethanol. Stir it magnetically for 20 to 30 minutes to obtain a silane solution. Immerse the wollastonite powder in the silane solution and stir it mechanically for 10 to 20 minutes. Then, treat it ultrasonically for 30 minutes. Then, filter it, dry it, and pass it through an 800-mesh sieve to obtain modified wollastonite powder.

9. The water-based inorganic thermal insulation coating according to claim 8, characterized in that: The usage ratio of KH-560, anhydrous ethanol and wollastonite powder is 0.2-0.5kg:2kg:10kg.

10. A method for preparing a water-based inorganic thermal insulation coating according to any one of claims 1 to 9, characterized in that: The following steps are involved: Weigh each raw material according to mass percentage, add cellulose ether, dispersant and defoaming agent into deionized water with stirring, stir at 400 rpm for 20 to 30 minutes, then add silica sol thereto with stirring, stir at 800 rpm for 10 to 20 minutes, after completion, add modified wollastonite powder and titanium dioxide thereto in sequence, stir at 400 rpm for 30 minutes, then add gradient-coated glass micropowder thereto with stirring, stir at 400 rpm for 5 to 10 minutes, after completion, obtain a water-based inorganic thermal insulation coating.

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