A multifunctional inorganic carbon-fixing coating, its preparation method and coating layer

Abstract

This invention relates to a multifunctional inorganic carbon-fixing coating, its preparation method, and the coating itself. By weight, the coating raw materials include 70-140 parts of carbon-cured composite material, 14-100 parts of deionized water, 10-70 parts of modified silica sol, and 1-14 parts of organic emulsion. The carbon-cured composite material is obtained by calcining a mixture of calcareous, siliceous, aluminous, and titanium raw materials. This invention, by incorporating calcareous, siliceous, aluminous, and titanium raw materials, prepares a carbon-cured composite material comprising multiphase minerals. This composite material is then combined with modified silica sol and organic emulsion to form an inorganic carbon-fixing coating. The multiphase minerals improve wear resistance and possess a high band gap and high refractive index. The modified silica sol and organic emulsion synergistically enhance the coating's cohesion. The inorganic carbon-fixing coating obtained using this invention exhibits excellent wear resistance, washability, and solar radiation reflection, as well as high adhesive strength.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a multifunctional inorganic carbon-fixing coating, its preparation method, and the coating itself. Background Technology

[0002] Water-based inorganic coatings are environmentally friendly, offering advantages over traditional organic coatings such as low VOC content, low flammability, and environmental friendliness. However, current water-based inorganic coatings on the market still have certain performance limitations, restricting their widespread application. Specifically, coatings using silicate (mainly sodium silicate and lithium silicate) aqueous solutions as inorganic film-forming agents exhibit poor water resistance. This is because silicate aqueous solutions easily redissolve in the presence of moisture, leading to coating degradation. This also results in the coating easily rubbing off powder after drying, reducing adhesion and abrasion resistance. On the other hand, inorganic coatings using silica sol as the main film-forming agent perform better in terms of water resistance, thanks to the cross-linked network structure formed by silica sol particles during curing, which effectively blocks moisture penetration. However, the curing process of this type of coating involves significant volume shrinkage, easily leading to coating cracking. Finally, both of these coatings require a reaction with CO2 in the air, resulting in long curing times.

[0003] In calcium silicate mineral phases, γ-type dicalcium silicate, with its high carbonization activity and high mechanical strength after curing, is considered a major binder component for novel water-based inorganic coatings. It can cure by absorbing CO2, simultaneously generating highly polymerized amorphous silica gel (binder) and insoluble calcium carbonate in situ. This curing process involves a certain degree of system expansion, thus gradually reducing porosity and effectively minimizing water penetration. Therefore, inorganic coatings with γ-type dicalcium silicate as the main component have significant advantages over the two inorganic coatings mentioned above.

[0004] Currently, patents CN202110166883.3 and CN202210323347.4 both use dicalcium silicate of the gamma type as the main binder component in the coating. They achieve different functionalized coatings through carbonization in a pressurized CO2 environment with a gas pressure of 0.1–0.6 MPa. However, due to the presence of a large amount of calcium carbonate and a low content of silica gel in the cured product, the coating exhibits poor wear resistance and scrub resistance. Under long-term service conditions, these coatings inevitably experience powdering and peeling. Meanwhile, CN202210323347.4 uses a solar radiation reflector with high solar radiation reflectivity to improve the coating's radiative cooling effect. However, its preparation process requires modification of the solar radiation reflector, and the interfacial adhesion between phases within the coating is low, resulting in relatively low overall adhesive strength. Therefore, improving the functionalization effect of inorganic carbon-fixing coatings through the external addition of functional materials inevitably leads to a decrease in coating cohesion. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a multifunctional inorganic carbon-fixing coating, its preparation method and coating, thereby solving the technical problems of poor wear resistance and scrubbing resistance and low bonding strength of inorganic carbon-fixing coatings with γ-type dicalcium silicate as the main binder in the prior art.

[0006] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows:

[0007] In a first aspect, the present invention provides a multifunctional inorganic carbon-fixing coating, wherein, by weight, the raw materials include 70-140 parts of carbon-curing composite material, 14-100 parts of deionized water, 10-70 parts of modified silica sol, and 1-14 parts of organic emulsion; wherein the carbon-curing composite material is obtained by calcining a mixture of calcium-based raw materials, silicon-based raw materials, aluminum-based raw materials, and titanium-based raw materials.

[0008] Secondly, the present invention provides a method for preparing a multifunctional inorganic carbon-fixing coating, comprising the following steps: ultrasonically mixing deionized water and organic emulsion until uniform, during which modified silica sol is slowly added dropwise to obtain a mixed solution; then adding carbon-cured composite material to the mixed solution and mixing uniformly to obtain an inorganic carbon-fixing coating.

[0009] Thirdly, the present invention provides a multifunctional inorganic carbon fixation coating, which is formed by coating an inorganic carbon fixation coating onto the surface of a substrate and then curing it in a CO2 environment.

[0010] Compared with the prior art, the beneficial effects of the present invention include:

[0011] This invention produces a carbon-cured composite material containing multiphase minerals such as γ-C2S by incorporating calcium, silicon, aluminum, and titanium raw materials. This composite material is then combined with modified silica sol and an organic emulsion to form an inorganic carbon-fixing coating. The multiphase minerals in the carbon-cured composite material enhance wear resistance, effectively addressing the poor wear and scrub resistance of single-γ-C2S mineral carbonized coatings in existing technologies. Simultaneously, the high bandgap and high refractive index of the multiphase minerals result in an inorganic carbon-fixing coating with excellent visible light radiation reflection and long-wave mid-infrared transparent window emission. The introduced modified silica sol and organic emulsion, which can generate an organic cross-linking network, fully utilize the cross-linking network function, synergistically enhancing the coating's cohesion, scrub resistance, and adhesion strength. Therefore, the inorganic carbon-fixing coating obtained using this invention exhibits excellent wear resistance, scrub resistance, and solar radiation reflection, along with high adhesion strength. Attached Figure Description

[0012] Figure 1 This is a backscattered image of the inorganic solid carbon coating obtained in Example 1 of the present invention;

[0013] Figure 2 This is a backscattered image of the inorganic solid carbon coating obtained in Comparative Example 2 of this invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0015] To address the poor abrasion resistance and scrub resistance of current inorganic carbon-fixing coatings with gamma-type dicalcium silicate as the main binder, and to impart more functional effects to the coating, this invention provides a multifunctional inorganic carbon-fixing coating that can be cured quickly and its preparation method. A carbon-cured composite material with gamma-type dicalcium silicate (γ-C2S) as the main component is prepared by firing, and by incorporating different coating additives, an inorganic carbon-fixing coating that can achieve multiple functions is finally obtained.

[0016] In a first aspect, the present invention provides a multifunctional inorganic carbon-fixing coating, wherein the raw materials, by weight, include 70-140 parts of carbon-curing composite material, 14-100 parts of deionized water, 10-70 parts of modified silica sol, and 1-14 parts of organic emulsion.

[0017] Among them, carbon-cured composite materials are obtained by mixing calcium-based raw materials, silicon-based raw materials, aluminum-based raw materials and titanium-based raw materials and then calcining them.

[0018] Preferably, the preparation method of the carbon-cured composite material specifically includes: wet mixing calcium raw materials, silicon raw materials, aluminum raw materials and titanium raw materials in a certain proportion for 0.5 to 2 hours, drying, calcining in a high-temperature furnace, and dry grinding the resulting clinker in a high-energy ball mill for 0.5 to 1 hour to finally obtain a carbon-cured composite material containing multiphase minerals, wherein the multiphase minerals include γ-C2S, Ca2Al2SiO7, and Ca2Ti. 1-x Si x O4 and CaTiO3. During wet mixing, the mass ratio of powder to water is 1:(1.1–1.3), more preferably 1:1.2. Wet mixing ensures uniform mixing of the phases and reduces interparticle spacing, facilitating subsequent firing. Direct dry mixing does not reduce interparticle spacing. The dry grinding step primarily grinds the fired carbon-cured composite material to a particle size range of 0.4 μm–70 μm. Within this particle size range, coatings prepared from the carbon-cured composite material exhibit the highest degree of carbon curing.

[0019] Preferably, the calcium-based raw material includes Ca(OH)2, the silicon-based raw material includes SiO2, the aluminum-based raw material includes Al2O3, and the titanium-based raw material includes TiO2.

[0020] Preferably, the purity of the calcium-based raw material is above 92%, the purity of the silicon-based raw material is above 95%, and the remaining impurities include MgO, BaO, SrO, ZrO2, Li2O, Na2O, K2O, B2O3, ZnO, Cs2O, and P2O5; the purity of the aluminum-based and titanium-based raw materials is above 99%; the particle size of the calcium-based, silicon-based, aluminum-based, and titanium-based raw materials is between 0.1 μm and 500 μm. The aluminum-based and titanium-based raw materials are used to provide functionalization.

[0021] Preferably, in the carbon-cured composite material, the calcium, silicon, aluminum, and titanium raw materials are proportioned in the following molar ratios: Ca / Si = 3.3–1.2, Al / Si < 2, Ti / Si < 1. Excessive or insufficient calcium-silicon ratio will result in a lower content of γ-C₂S, which plays a binding role, in the carbon-cured composite material. If the aluminum-silicon and titanium-silicon ratios are outside these ranges, other aluminum- and titanium-containing silicate mineral phases will be formed.

[0022] Further preferred ratios are Ca / Si = 3.3–2.0, Al / Si = 0.07–0.95, and Ti / Si = 0.03–0.82.

[0023] Preferably, the calcination treatment method is as follows: calcining the raw material in a box furnace at a temperature of 1250–1400°C for a time of 30–180 min. However, excessively low calcination temperature or insufficient calcination time will result in excessively high levels of free calcium oxide in the carbon-cured composite material, while excessively high temperature or prolonged calcination will lead to a decrease in the γ-C2S content.

[0024] Preferably, the finally obtained carbon solidified composite material contains multiphase minerals. By mass percentage, the multiphase minerals include 30-55 wt% of γ-C2S, and the rest is the sum of Ca2Al2SiO7, Ca2Ti 1-x Si x O4 and CaTiO3, and further preferably, the multiphase minerals include 30-55 wt% of γ-C2S, 2-45% of Ca2Al2SiO7, 6-35% of Ca2Ti 1-x Si x O4 and 2-20% of CaTiO3, where 0 < x < 1; and the content ratio of Ca2Al2SiO7 to Ca2Ti 1-x Si x O4 + CaTiO3 is 0.03-5.5. Specifically, under the same other conditions, the relative contents of Ca2Al2SiO7, Ca2Ti 1-x Si x O4 and CaTiO3 are determined according to the requirements of the multifunctional inorganic carbon fixation coating. Ca2Al2SiO7 is more conducive to improving the brushing resistance, and Ca2Ti 1-x Si x O4 + CaTiO3 is more conducive to synergistically improving the reflection ability. In the present invention, the mineral phase composition is jointly controlled by the raw material ratio and the firing regime. For the coating with the main requirement of high brushing resistance, the content ratio of Ca2Al2SiO7 to Ca2Ti 1-x Si x O4 + CaTiO3 is 5.5-1, and for the coating with the main requirement of high solar radiation 4 reflection ability, the content ratio of Ca2Al2SiO7 to Ca2Ti 1-x Si x O4 + CaTiO3 is 0.03-1.

[0025] It should be noted here that Ca2Ti 1-x Si x O4 may be a mixture composed of multiple crystal combinations of Ca2Ti 0.24 Si 0.76 O4, Ca2Ti 0.1 Si 0.9 O4, Ca2Ti 0.06 Si 0.94 O4. These crystals cannot be clearly distinguished by XRD and there is not much difference in actual properties, so it is abbreviated as Ca2Ti 1-x Si x O4, 0 < x < 1.

[0026] Preferably, the preparation steps of the modified silica sol include: dissolving chitosan in a 1% (w / w) acetic acid solution to obtain a chitosan solution; adding the chitosan solution to the silica sol, adjusting the pH to 8.5–9.5, stirring evenly, and aging for at least 24 hours to obtain the modified silica sol; wherein the mass ratio of acetic acid solution to chitosan is 100:(4–6), and the mass ratio of silica sol to chitosan solution is 100:(8–12). The modified silica sol of this invention is modified through organic hybridization, enabling it to protect inorganic silica sol and inhibit aggregation under alkaline conditions.

[0027] Preferably, the modified silica sol has a solid content of 33±5%.

[0028] Preferably, the organic emulsion includes one or a mixture of multiple types of acrylate emulsion, styrene-acrylic emulsion, pure acrylic emulsion, epoxy resin emulsion, EVA emulsion, and silicone-acrylic emulsion in any proportion; the solid content of the organic emulsion is 40-50%.

[0029] Further preferably, the organic emulsion has a solid content of 45%.

[0030] Secondly, the present invention provides a method for preparing a multifunctional inorganic carbon-fixing coating, comprising the following steps:

[0031] Deionized water and organic emulsion were ultrasonically mixed until homogeneous, and modified silica sol was slowly added dropwise during the process to obtain a mixed solution;

[0032] Then, the carbon-cured composite material is added to the mixed solution and mixed evenly to obtain an inorganic carbon-fixed coating.

[0033] Preferably, deionized water and organic emulsion are ultrasonically mixed for 15-25 minutes until homogeneous; carbon-cured composite material is added to the mixed solution and dispersed at 2500-3500 r / min for 0.5-1.5 hours until homogeneous.

[0034] Thirdly, the present invention provides a multifunctional inorganic carbon fixation coating, which is formed by coating an inorganic carbon fixation coating onto the surface of a substrate and then placing it in a CO2-rich environment for curing.

[0035] Preferably, the substrate includes a concrete building base or a steel structure with a silanized surface.

[0036] Preferably, the coating is applied by spraying, rolling, or pressing; the coating thickness is 0.3–3 mm.

[0037] Preferably, the curing regime is as follows: CO2 concentration is 5% to 100%, CO2 partial pressure is 0.01 MPa to 7.4 MPa, and carbonization time is 0.1 to 72 h. In this invention, the curing method can be CO2 jet curing or film-coated gas curing. For precast components, pressurized curing can be carried out in the reaction tank, while others can be cured at atmospheric pressure.

[0038] The main mechanism of action and advantages of this invention are as follows:

[0039] (1) In the process of preparing γ-C2S by firing, a certain mass percentage of functional raw materials such as Al2O3 and TiO2 are incorporated. Excessive use of functional raw materials will result in a lower content of γ-C2S, which plays a binding role, in the carbon-cured composite material; insufficient use will result in the carbon-cured composite material failing to achieve the optimal functionalization effect. By optimizing the firing process, a composite material with gamma-type dicalcium silicate (γ-C2S) as the main component, and also containing Ca2Al2SiO7 and Ca2TiO2, is prepared. 1-x Si x Carbon-cured composite materials made from minerals such as O4 and CaTiO3. Ca2Al2SiO7 has a Mohs hardness of 6.5, and CaTiO3 has a Mohs hardness of 6, exhibiting higher wear resistance compared to γ-C2S (Mohs hardness 5) and its carbonization product CaCO3 (Mohs hardness 3). Inorganic carbon-fixed coatings prepared using these multiphase minerals can effectively improve the poor wear resistance and scrub resistance of existing single-γ-C2S mineral carbonized coatings.

[0040] (2) By incorporating Al2O3 or TiO2, the present invention results in a carbon-cured composite material containing a portion of Ca2Al2SiO7 and Ca2Ti. 1-x Si x O4 and CaTiO3. These substances, along with the carbide product CaCO3, possess high band gaps and high refractive indices. This results in inorganic carbon-fixing coatings prepared using these multiphase minerals exhibiting excellent visible light radiation reflection and long-wave mid-infrared transparent window emission. Such coatings demonstrate high radiative cooling efficiency when applied to concrete and steel structures.

[0041] (3) This invention incorporates different functionalized mineral phases during the preparation of γ-C2S and optimizes its firing process, ultimately obtaining a variety of functionalized carbon-cured composite materials through firing alone; secondly, by incorporating coating additives and appropriate coating preparation processes, multifunctional inorganic carbon-fixing coatings are obtained. Compared with single γ-C2S mineral carbon-fixing coatings and carbon-fixing coatings obtained through mechanical mixing, these coatings exhibit superior carbonization reactivity and system compatibility.

[0042] To make the objectives, techniques / solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] To avoid redundancy, the main raw materials are described here. Among the raw materials of carbon-cured composite materials, the calcium-based raw material is Ca(OH)2, the silicon-based raw material is SiO2, the aluminum-based raw material is Al2O3, and the titanium-based raw material is TiO2.

[0044] In the raw materials of the inorganic carbon-fixing coating, the silica sol uses S309 from Shanghai Xinshou Additives Co., Ltd.; the modified silica sol is an organic hybrid modified silica sol with a solid content of 33%. The specific preparation steps of the organic hybrid modified silica sol include: dissolving chitosan powder in a 1% acetic acid solution, stirring continuously at 300 rpm / s for 20 min to prepare a 5% chitosan solution; then slowly adding the chitosan solution with a 10% dosage to the silica sol, adjusting the pH of the mixture to about 9 with ammonia water, and stirring continuously at 300 rpm / s for 1 h to ensure thorough mixing; and then aging for 1 day.

[0045] The solid content of all organic emulsions is 45%.

[0046] In each embodiment and comparative example, the preparation method of the inorganic carbon-fixing coating includes the following steps: ultrasonically mixing deionized water and organic emulsion for 20 min, during which modified silica sol is slowly added dropwise; then the carbon-cured composite material is added to the mixed solution in three parts, and after the previous part of the carbon-cured composite material is added, the mixture is stirred for 5 min before the next part is added, and the mixture is dispersed at a high speed of 3000 r / min for 1 h, and finally the inorganic carbon-fixing coating is prepared.

[0047] Example 1

[0048] The inorganic carbon-fixing coating of this embodiment consists of: 85 parts carbon-curing composite material, 14 parts deionized water, 35 parts modified silica sol and 7 parts organic emulsion (styrene-acrylic emulsion).

[0049] The raw material mixing ratio for the carbon-cured composite material was as follows: Ca / Si = 2.1, Al / Si = 0.72, and Ti / Si = 0.08. After wet mixing for 2 hours, the mixture was dried and then calcined at 1400℃ for 3 hours, followed by dry grinding for 0.5 hours to obtain the carbon-cured composite material. XRD analysis revealed its mineral composition (all by mass percentage) to be: 51% γ-C₂S, 33% Ca₂Al₂SiO₇, and 10% Ca₂Ti. 1-x Si x O4 and 6% CaTiO3.

[0050] Inorganic carbon-fixing coating was sprayed onto a concrete substrate with a coating thickness of 0.3 mm; 100% CO2 gas was introduced, and the coating was carbonized and cured for 20 minutes under normal pressure to obtain a multifunctional inorganic carbon-fixing coating.

[0051] Example 2

[0052] The inorganic carbon-fixing coating of this embodiment comprises: 100 parts carbon-curing composite material, 28 parts deionized water, 48 parts modified silica sol and 10 parts organic emulsion; the organic emulsion is a combination of epoxy resin emulsion (solid content of 45%) and acrylic emulsion (solid content of 45%) in a mass ratio of 1:2.

[0053] The raw material proportions for preparing the carbon-cured composite material were as follows: Ca / Si = 2.4, Al / Si = 0.58, and Ti / Si = 0.28. After wet mixing for 2 hours, the mixture was dried and then calcined at 1350℃ for 3 hours, followed by dry grinding for 1 hour to obtain the carbon-cured composite material. XRD analysis revealed its mineral composition to be: 45% γ-C₂S, 23% Ca₂Al₂SiO₇, and 20% Ca₂Ti. 1-x Si x O4 and 12% CaTiO3.

[0054] Inorganic carbon-fixing coating was sprayed onto a concrete substrate with a coating thickness of 1 mm; after passing through 60% CO2 gas and carbonizing and curing at normal pressure for 2 hours, a multifunctional inorganic carbon-fixing coating was obtained.

[0055] Example 3

[0056] The inorganic carbon-fixing coating of this embodiment comprises: 70 parts carbon-curing composite material, 35 parts deionized water, 40 parts modified silica sol and 4 parts organic emulsion; the organic emulsion is a combination of styrene-acrylic emulsion and acrylic emulsion (both with a solid content of 45%), in a mass ratio of 2:3.

[0057] The raw material proportions for preparing the carbon-cured composite material were as follows: Ca / Si = 2.2, Al / Si = 0.95, and Ti / Si = 0.16. After wet mixing for 1 hour, the mixture was dried and then calcined at 1325℃ for 2 hours, followed by dry grinding for 1 hour to obtain the carbon-cured composite material. XRD analysis revealed its mineral composition to be: 40% γ-C₂S, 45% Ca₂Al₂SiO₇, and 15% Ca₂Ti. 1-x Si x O4 and 10% CaTiO3.

[0058] Inorganic carbon-fixing coating was sprayed onto a concrete substrate with a coating thickness of 0.5 mm; after introducing 20% ​​CO2 gas and carbonizing and curing at normal pressure for 24 hours, a multifunctional inorganic carbon-fixing coating was obtained.

[0059] Example 4

[0060] The inorganic carbon-fixing coating of this embodiment comprises: 97 parts carbon-curing composite material, 38 parts deionized water, 70 parts modified silica sol and 12 parts organic emulsion; the organic emulsion is a combination of pure acrylic emulsion and epoxy resin emulsion (both with a solid content of 45%), in a mass ratio of 1:1.

[0061] The raw material proportions for preparing the carbon-cured composite material were as follows: Ca / Si = 2.2, Al / Si = 0.24, and Ti / Si = 0.21 molar ratios. After wet mixing for 1 hour, the mixture was dried and then calcined at 1350℃ for 3 hours, followed by dry grinding for 0.5 hours to obtain the carbon-cured composite material. XRD analysis revealed its mineral composition to be: 42% γ-C₂S, 10% Ca₂Al₂SiO₇, and 33% Ca₂Ti. 1-x Si x O4 and 15% CaTiO3.

[0062] Inorganic carbon-fixing coating was sprayed onto a concrete substrate with a coating thickness of 0.5 mm; 100% CO2 gas was introduced, and the coating was carbonized and cured for 12 hours under normal pressure to obtain a multifunctional inorganic carbon-fixing coating.

[0063] Example 5

[0064] The inorganic carbon-fixing coating of this embodiment comprises: 88 parts carbon-curing composite material, 63 parts deionized water, 39 parts modified silica sol and 8 parts organic emulsion; the organic emulsion is a combination of styrene-acrylic emulsion and pure acrylic emulsion (both with a solid content of 45%), in a mass ratio of 1:1.

[0065] The raw material proportions for preparing the carbon-cured composite material were as follows: Ca / Si = 2.0, Al / Si = 0.87, and Ti / Si = 0.03. After wet mixing for 2 hours, the mixture was dried and then calcined at 1400℃ for 2 hours, followed by dry grinding for 1 hour to obtain the carbon-cured composite material. XRD analysis revealed its mineral composition to be: 50% γ-C₂S, 42% Ca₂Al₂SiO₇, and 6% Ca₂Ti. 1-x Si x O4 and 2% CaTiO3.

[0066] Inorganic carbon-fixing coating was sprayed onto a concrete substrate with a coating thickness of 0.4 mm; after carbonization curing for 8 hours under 0.1 MPa environment with 100% CO2 gas, a multifunctional inorganic carbon-fixing coating was obtained.

[0067] Example 6

[0068] The inorganic carbon-fixing coating of this embodiment comprises: 120 parts carbon-curing composite material, 40 parts deionized water, 58 parts modified silica sol and 14 parts organic emulsion; the organic emulsion is a combination of epoxy resin emulsion and EVA emulsion (both with a solid content of 45%), with a mass ratio of 2:1.

[0069] The raw material proportions for preparing the carbon-cured composite material were as follows: Ca / Si = 2.6, Al / Si = 0.58, and Ti / Si = 0.39 molar ratios. After wet mixing for 2 hours, the mixture was dried and then calcined at 1400℃ for 2 hours, followed by dry grinding for 1 hour to obtain the carbon-cured composite material. XRD analysis revealed its mineral composition to be: 41% γ-C₂S, 21% Ca₂Al₂SiO₇, and 22% Ca₂Ti. 1-x Si x O4 and 16% CaTiO3.

[0070] Inorganic carbon-fixing coating was sprayed onto a silanized steel structure substrate with a coating thickness of 1.5 mm. After passing through 100% CO2 gas and carbonizing and curing at normal pressure for 24 hours, a multifunctional inorganic carbon-fixing coating was obtained.

[0071] Example 7

[0072] The inorganic carbon-fixing coating of this embodiment comprises: 105 parts carbon-curing composite material, 50 parts deionized water, 26 parts modified silica sol and 7 parts organic emulsion; the organic emulsion is an epoxy resin emulsion with a solid content of 45%.

[0073] The raw material proportions for preparing the carbon-cured composite material were as follows: Ca / Si = 3.3, Al / Si = 0.07, and Ti / Si = 0.82. After wet mixing for 1 hour, the mixture was dried and then calcined at 1350℃ for 3 hours, followed by dry grinding for 0.5 hours to obtain the carbon-cured composite material. XRD analysis revealed its mineral composition to be: 43% γ-C₂S, 2% Ca₂Al₂SiO₇, and 35% Ca₂Ti. 1-x Si x O4 and 20% CaTiO3.

[0074] Inorganic carbon-fixing coating was sprayed onto a silanized steel structure substrate with a coating thickness of 1.8 mm. After passing through 100% CO2 gas and carbonizing and curing at 0.1 MPa for 24 hours, a multifunctional inorganic carbon-fixing coating was obtained.

[0075] Comparative Example 1

[0076] An inorganic carbon-fixing coating differs from Example 1 only in that the carbon-cured composite material is obtained by mechanical mixing, while the other steps and conditions are the same as in Example 1; the difference lies in:

[0077] The raw material mixing ratio for carbon-cured composite materials was set at a molar ratio of Ca / Si = 2.0. After wet mixing for 2 hours, the mixture was dried and then calcined at 1400℃ for 3 hours. Following calculations, Ca2Al2SiO7, CaTiO3, and Ca2Ti were added. 1-x Si x O4. After mechanical mixing for 2 hours, dry grinding was performed for 0.5 hours. The final product, calculated by mass percentage, included: 51% γ-C2S, 33% Ca2Al2SiO7, and 10% Ca2Ti. 1-x Si x O4 and 6% CaTiO3.

[0078] Comparative Example 2

[0079] An inorganic carbon-fixing coating differs from Example 1 only in that the carbon-cured composite material is replaced with the same amount of γ-C2S, while the other steps and conditions are the same as in Example 1.

[0080] Comparative Example 3

[0081] An inorganic carbon-fixing coating differs from Example 1 only in that the inorganic carbon-fixing coating consists of 85 parts carbon-curing composite material and 14 parts deionized water; the other steps and conditions are the same as in Example 1.

[0082] Comparative Example 4

[0083] An inorganic carbon-fixing coating differs from Example 1 only in that Al2O3 is removed during the preparation of the carbon-cured composite material; all other steps and conditions are the same as in Example 1.

[0084] Comparative Example 5

[0085] An inorganic carbon-fixing coating differs from Example 1 only in that TiO2 is removed during the preparation of the carbon-cured composite material; the other steps and conditions are the same as in Example 1.

[0086] Evaluation Test

[0087] The above embodiments and comparative examples were dispersed under the same regime according to the corresponding proportions and applied to the corresponding boards. Carbonization curing was carried out at room temperature for the corresponding time and regime according to the corresponding carbonization curing regime. After curing, scrub resistance was tested according to GB / T 9266 standard; solar reflectance, near-infrared reflectance, and thermal insulation temperature difference with the reference blackboard were tested according to GB / T 25261-2018 and JG / T 235—2014 standards; adhesive strength was tested according to GB / T 9779—2015 standard; finally, the degree of carbonization was determined by the thermal burn-off method. The results are shown in Table 1 below.

[0088] Table 1. Test results of Examples 1-7 and Comparative Examples 1-5

[0089]

[0090] As shown in Table 1, the present invention exhibits excellent washability and solar radiation reflection. Examples 1-7 all demonstrate washability exceeding 5000 cycles, while the thermal insulation temperature difference with the reference blackboard reaches a maximum of 32°C. Specifically, the inorganic carbon-fixed coating obtained by the present invention achieves washability of 5011-5421 cycles, a solar reflectance of 0.9-0.96, a near-infrared reflectance of 0.89-0.93, a thermal insulation temperature difference with the reference blackboard of 25-32°C, and an adhesion strength of 3.37-8.41 MPa.

[0091] A comparison of Example 1 and Comparative Example 1 shows that the carbon-cured composite material prepared by sintering in this invention exhibits higher carbonization activity and higher bonding strength compared to multiphase minerals obtained through mechanical mixing. This is because the interfacial bonding strength of each phase in the carbon-cured composite material prepared by sintering is higher after carbonization, thus improving its washability.

[0092] A comparison of Example 1 and Comparative Example 2 shows that the carbon-cured composite material used in this invention contains multiphase minerals. Compared to Comparative Example 2 (100% γ-C2S content), the γ-C2S content is reduced. The results indicate that the carbon-cured composite material with multiphase minerals in this invention has higher carbonization activity. This is evident from… Figure 1 (Example 1) and Figure 2 As can be seen in Comparative Example 2, γ-C2S produces more carbonization products (gray parts in the figure) under relatively low content conditions, which in turn fill the voids in the coating (black parts in the figure). Figure 1 The gaps are significantly less than Figure 2 The gaps significantly improve the density of the coating.

[0093] Since the silica gel network generated during carbonization is relatively small and cannot fully function as a cross-linking network, it is necessary to introduce modified silica sol and organic emulsions that can generate organic cross-linking networks to synergistically enhance the cohesiveness of the coating. As can be seen from Example 1 and Comparative Example 3, the various properties of the coating decreased after removing the modified silica sol and organic emulsion.

[0094] As can be seen from Example 1 and Comparative Examples 4-5, removing the aluminum and titanium raw materials from the carbon-cured composite material will affect the performance of the resulting inorganic carbon-cured coating.

[0095] This invention discloses a multifunctional inorganic carbon-fixing coating. The coating forms a layer that simultaneously possesses high washability and high solar radiation reflectivity. γ-C2S in the coating serves as the main binder, while other mineral phases contribute to different functionalities. Through the overall solar reflectance and near-infrared reflectance of the coating, it can achieve radiative cooling through a long-wave mid-infrared transparent window, thereby achieving passive cooling of the building interior. Simultaneously, the coating employs CO2 curing, achieving curing through CO2 absorption, offering the advantages of low carbon footprint and environmental friendliness. Furthermore, this coating exhibits better resistance to weathering and UV aging, resulting in a longer service life.

[0096] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A multifunctional inorganic carbon-fixing coating, comprising, by weight, 70-140 parts carbon-curing composite material, 14-100 parts deionized water, 10-70 parts modified silica sol, and 1-14 parts organic emulsion; in, Carbon-cured composite materials are obtained by mixing calcium-based raw materials, silicon-based raw materials, aluminum-based raw materials, and titanium-based raw materials, followed by calcination. The calcium-based raw materials, silicon-based raw materials, aluminum-based raw materials, and titanium-based raw materials are formulated in the following molar ratios: Ca / Si = 3.3–1.2, Al / Si < 2, Ti / Si < 1; The calcium-based, silicon-based, aluminum-based, and titanium-based raw materials are wet-mixed, dried, calcined, and dry-milled to obtain a carbon-cured composite material containing multiphase minerals. The multiphase minerals comprise 30–55% γ-C₂S, with the remainder being Ca₂Al₂SiO₇ and Ca₂Ti. 1-x Si x O4 and CaTiO3, of which 0 <x<1; The calcination process is carried out at a temperature of 1250–1400°C for 30–180 minutes.

2. The multifunctional inorganic carbon-fixing coating according to claim 1, characterized in that, The calcium-based raw material includes Ca(OH)2, the silicon-based raw material includes SiO2, the aluminum-based raw material includes Al2O3, and the titanium-based raw material includes TiO2; the particle size of the calcium-based raw material, silicon-based raw material, aluminum-based raw material, and titanium-based raw material is between 0.1μm and 500μm.

3. The multifunctional inorganic carbon-fixing coating according to claim 1, characterized in that, The particle size of the carbon-cured composite material is between 0.4 μm and 70 μm.

4. The multifunctional inorganic carbon-fixing coating according to claim 1, characterized in that, The preparation steps of the modified silica sol include: dissolving chitosan in a 1% (w / w) acetic acid solution to obtain a chitosan solution; adding the chitosan solution to the silica sol, adjusting the pH to 8.5–9.5, stirring evenly, and aging for more than 24 hours to obtain the modified silica sol; wherein, the mass ratio of acetic acid solution to chitosan is 100:(4–6), and the mass ratio of silica sol to chitosan solution is 100:(8–12). The solid content of the modified silica sol is 28-38%.

5. The multifunctional inorganic carbon-fixing coating according to claim 1, characterized in that, The organic emulsion includes one or a mixture of multiple types of acrylate emulsion, styrene-acrylic emulsion, pure acrylic emulsion, epoxy resin emulsion, EVA emulsion, and silicone-acrylic emulsion in any proportion; the solid content of the organic emulsion is 40-50%.

6. The method for preparing the multifunctional inorganic carbon-fixing coating according to any one of claims 1-5, characterized in that, Includes the following steps: Deionized water and organic emulsion were ultrasonically mixed until homogeneous, while modified silica sol was slowly added dropwise to obtain a mixed solution. Then, the carbon-cured composite material is added to the mixed solution and mixed evenly to obtain an inorganic carbon-fixed coating.

7. The method for preparing the multifunctional inorganic carbon-fixing coating according to claim 6, characterized in that, Deionized water and organic emulsion are ultrasonically mixed for 15-25 minutes until homogeneous; carbon-cured composite material is added to the mixed solution and dispersed at 2500-3500 r / min for 0.5-1.5 hours until homogeneous.

8. An inorganic carbon-fixing coating, characterized in that, The inorganic carbon fixation coating is formed by coating an inorganic carbon fixation paint onto the surface of a substrate and then curing it in a CO2 environment; the inorganic carbon fixation paint is the inorganic carbon fixation paint according to any one of claims 1-5.

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