Door and window aluminum material surface heat insulation coating technology

Abstract

The invention discloses a door and window aluminum surface heat insulation coating process, belongs to the technical field of heat insulation coatings, and remarkably improves the heat insulation performance and bonding strength of a coating by optimizing a formula and a preparation process of a heat preservation and heat insulation coating. The specific process comprises the steps that after the surface of the door and window aluminum material is cleaned through a spray gun, heat-preservation and heat-insulation paint is evenly sprayed, segmented drying treatment is conducted, and then the heat-insulation coating is formed through the heating and heat-preservation step. The preparation of the thermal insulation coating relates to a plurality of raw materials, including triisopropyl alcohol methyl titanium, zirconium nitrate, lanthanum nitrate and citric acid. Compared with the prior art, the coating disclosed by the invention is low in heat conductivity coefficient, high in bonding strength and simple and feasible in process, meets the environmental protection requirement and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of heat-insulating coatings, and in particular to a heat-insulating coating process for the surface of aluminum materials for doors and windows. Background Art

[0002] In the fields of architecture and industry, the thermal insulation performance of aluminum doors and windows has always been one of the key factors affecting building energy conservation and comfort. Traditional thermal insulation technology usually relies on heavy thermal insulation materials or complex structural designs, such as thermally insulated aluminum. Although it has certain advantages in thermal insulation effect, it has problems such as high cost, heavy weight, and complex construction. In addition, the thermal insulation performance of these materials in high temperature environments is often not ideal, making it difficult to meet the needs of modern buildings for efficient thermal insulation and energy saving.

[0003] In recent years, with the development of nanotechnology, the application of nanomaterials in thermal insulation coatings has gradually attracted attention. Due to their unique size effect and surface characteristics, nanomaterials can significantly reduce the thermal conductivity of coatings while improving the adhesion and durability of coatings. However, the preparation process of nano thermal insulation coatings in the prior art is complicated, and in practical applications, there are problems such as insufficient coating adhesion and unstable thermal insulation performance.

[0004] In addition, the thermal insulation coatings in the prior art mostly use a single surface modifier or chelating agent, which is difficult to meet the comprehensive requirements of thermal insulation performance, adhesion and durability at the same time. For example, although some coatings have good thermal insulation performance, they are prone to fall off due to insufficient adhesion during long-term use, resulting in a decrease in thermal insulation effect; while other coatings have strong adhesion, but the thermal insulation performance is not ideal and cannot effectively reduce heat transfer.

[0005] Therefore, developing an efficient, stable and easy-to-construct thermal insulation coating process for the surface of aluminum doors and windows is of great significance for improving building energy conservation and reducing energy consumption.

[0006] Chinese invention patent CN118374174A discloses a thermal insulation coating and its preparation method, and a preparation method of a thermal insulation coating. The preparation method of the thermal insulation coating of the invention adopts a room temperature spraying process, does not require expensive equipment, has a simple process operation, and is low in cost; the coating does not need high-temperature sintering, and can utilize the heating of the refractory material during use to induce an in-situ reaction inside the coating, thereby obtaining a rare earth-doped zirconia thermal insulation coating, which is conducive to reducing production energy consumption and saving costs; the coating can be repaired by simple spraying, which can not only protect the refractory material, but also has good maintainability; the rare earth-doped zirconia coating prepared by the invention through a simple preparation process can not only significantly improve the thermal insulation performance of the refractory material, especially the thermal insulation performance at high temperature, but also has good thermal stability and high temperature erosion resistance, and a long service life. The technical process is simple, low-cost, and has a wide range of applications, and has broad application prospects. However, the thermal insulation coating prepared by this method still has room for improvement in terms of thermal insulation performance and bonding strength. Summary of the invention

[0007] In order to address the deficiencies in the prior art, the present invention aims to solve the problems existing in the prior art by optimizing the formula and preparation process of the thermal insulation coating, and to provide a high-performance thermal insulation coating process for the surface of aluminum doors and windows.

[0008] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0009] A thermal insulation coating process for the surface of aluminum doors and windows is as follows:

[0010] Step 1, use a spray gun to clean the surface of the aluminum material of the doors and windows to remove the slag and dust on the surface; spray the thermal insulation coating evenly on the surface of the aluminum material of the doors and windows, and then perform a segmented drying process: first dry at 50-60°C for 10-30 minutes, then dry at 60-80°C for 20-40 minutes, and finally dry at 80-100°C for 10-40 minutes; spray a second time on the basis of the coating after the first drying, first dry at 40-60°C for 10-30 minutes, then dry at 60-80°C for 10-30 minutes, and finally dry at 80-100°C for 20-40 minutes;

[0011] Step 2: heating the door and window aluminum material dried in step 1 to 100-120° C., keeping the temperature for 5-20 minutes, and then naturally cooling it to room temperature, finally forming a heat insulation coating on the surface of the door and window aluminum material.

[0012] The thickness of the first coating layer is 0.5-1.5 mm.

[0013] The second coating has a thickness of 0.5 to 1.5 mm.

[0014] The heating rate in step 2 is 1-2°C / min.

[0015] The preparation method of the thermal insulation coating is as follows, in parts by weight:

[0016] S1, adding 180-220 parts of methyl titanium triisopropoxide to 800-1200 parts of 50-70wt% propylene glycol aqueous solution, stirring for 10-30 minutes, then transferring the mixed solution to a reactor, reacting at 200-220° C. for 10-30 hours, cooling to room temperature after the reaction, washing with water and anhydrous ethanol for 1-3 times respectively, placing the product in a vacuum drying oven, and drying at 100-120° C. overnight to obtain a pretreated product;

[0017] S2, dispersing 80 to 120 parts of the pre-treated product obtained in step S1 in 400 to 600 parts of a phosphate buffer solution, adding 18 to 22 parts of 3-aminopropyltriethoxysilane, stirring at room temperature for 10 to 30 hours, filtering the stirred suspension, collecting a solid product, and obtaining a post-treated product;

[0018] S3. Mix 250-350 parts of zirconium nitrate with 350-450 parts of lanthanum nitrate, 80-120 parts of citric acid, 60-100 parts of the post-treated product obtained in step S2, 30-50 parts of sodium silicate, 4-6 parts of film-forming aid, 0.5-2 parts of defoaming agent, 1-1.5 parts of dispersant and 700-900 parts of water, stir well to obtain a thermal insulation coating.

[0019] Preferably, the preparation method of the thermal insulation coating is as follows, in parts by weight:

[0020] S1, adding 180-220 parts of methyl titanium triisopropoxide to 800-1200 parts of 50-70wt% propylene glycol aqueous solution, stirring for 10-30 minutes, then transferring the mixed solution to a reactor, reacting at 200-220° C. for 10-30 hours, cooling to room temperature after the reaction, washing with water and anhydrous ethanol for 1-3 times respectively, placing the product in a vacuum drying oven, and drying at 100-120° C. overnight to obtain a pretreated product;

[0021] S2, dispersing 80 to 120 parts of the pre-treated product obtained in step S1 in 400 to 600 parts of a phosphate buffer solution, adding 8 to 12 parts of dopamine hydrochloride and 8 to 12 parts of ethylenediamine, stirring at room temperature for 10 to 30 hours, filtering the stirred suspension, collecting a solid product, and obtaining a post-treated product;

[0022] S3. Mix 250-350 parts of zirconium nitrate with 350-450 parts of lanthanum nitrate, 80-120 parts of citric acid, 60-100 parts of the post-treated product obtained in step S2, 30-50 parts of sodium silicate, 4-6 parts of film-forming aid, 0.5-2 parts of defoaming agent, 1-1.5 parts of dispersant and 700-900 parts of water, stir well to obtain a thermal insulation coating.

[0023] The film-forming aid is at least one of hydroxypropyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, polyvinyl alcohol, bentonite and starch.

[0024] The defoaming agent is a silicone defoaming agent.

[0025] The dispersant is a polyphosphate dispersant.

[0026] In the heat-insulating coating process for the surface of aluminum door and window of the present invention, the functions of various substances are as follows:

[0027] Methyl titanium triisopropoxide is used as a precursor to synthesize titanium-based compounds with special structures.

[0028] Propylene glycol aqueous solution is used as a solvent to dissolve methyl titanium triisopropoxide.

[0029] Phosphate buffer solution was used to disperse the pretreatment.

[0030] As a surface modifier, 3-aminopropyltriethoxysilane reacts with the hydroxyl groups on the surface of nanoparticles through its amino functional groups to form stable chemical bonds, thereby improving the surface properties of the nanoparticles, enhancing their compatibility with organic matrices, and improving the adhesion and stability of the coating.

[0031] Dopamine hydrochloride, as a surface modifier, forms a uniform polymer coating on the surface of nanoparticles through self-polymerization, enhancing the chemical stability and mechanical strength of the nanoparticles. At the same time, the amino functional group of dopamine can form a strong interaction with inorganic nanoparticles and organic matrices, further improving the adhesion and thermal insulation properties of the coating.

[0032] Ethylenediamine acts as a cross-linking agent to undergo a cross-linking reaction with the hydroxyl groups on the surface of the nanoparticles, thereby enhancing the bonding force between the nanoparticles and the organic matrix, optimizing the microstructure of the coating, increasing the porosity of the coating, reducing the thermal conductivity, and improving the thermal insulation performance.

[0033] Zirconium nitrate and lanthanum nitrate act as metal oxide precursors to form a stable oxide structure in the coating, providing good thermal stability and thermal insulation properties.

[0034] Citric acid acts as a chelating agent to form stable complexes with metal ions (such as zirconium nitrate and lanthanum nitrate), promotes the uniform dispersion of metal ions, optimizes the microstructure of the coating, reduces thermal conductivity, and improves thermal insulation performance.

[0035] Sodium silicate acts as an inorganic binder to enhance the adhesion and mechanical properties of the coating and improve the durability of the coating.

[0036] Polyvinyl alcohol as a film-forming aid provides good film-forming properties and enhances the flexibility and adhesion of the coating.

[0037] Polydimethylsiloxane as a defoaming agent gives the coating good lubricity and hydrophobicity, reduces scale adsorption and prolongs service life.

[0038] Sodium hexametaphosphate acts as a dispersant to prevent nanoparticles from agglomerating and ensure uniformity of the coating.

[0039] The synergistic effect of these substances enables the coating of the present invention to perform excellently in terms of heat insulation, adhesion and durability, and meets the high requirements of aluminum materials for building doors and windows for heat insulation and energy saving.

[0040] Compared with the prior art, it has the following beneficial effects:

[0041] 1) The present invention optimizes the formula and preparation process of the thermal insulation coating, especially uses specific organic acids and functional additives to modify the surface of the nanomaterials, which significantly reduces the thermal conductivity of the coating and exhibits excellent thermal insulation performance. This optimized coating structure can effectively reduce heat transfer and improve the thermal insulation effect of aluminum doors and windows.

[0042] 2) The present invention significantly improves the bonding strength between the coating and the aluminum substrate through multi-step surface treatment and the introduction of specific additives. This high-strength bonding performance ensures that the coating is not easy to fall off during long-term use, enhances the durability and reliability of the coating, and extends the service life of aluminum doors and windows.

[0043] 3) The coating process of the present invention not only improves the thermal insulation and bonding properties, but also improves the comprehensive performance of the coating by optimizing the formula and process. In addition, the process meets environmental protection requirements, does not use harmful substances, reduces the impact on the environment, and has broad application prospects and market value. DETAILED DESCRIPTION

[0044] Main sources of substances:

[0045] Phosphate buffer solution, model: LA1812, pH 7.2-7.4, main components are potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium chloride and potassium chloride, Fuzhou Feijing Biotechnology Co., Ltd.

[0046] Polyvinyl alcohol, product number: 363170, molecular weight: Mw 13,000-23,000, 87-89% hydrolyzed, was purchased from Merck.

[0047] Polydimethylsiloxane, product number: 81153, molecular weight Mw: 311, was purchased from Merck.

[0048] The remaining raw materials in the examples and comparative examples of the present invention are all commercially available products.

[0049] The design idea of ​​the present invention is to develop a high-performance thermal insulation coating for the surface of aluminum doors and windows by optimizing the formula and preparation process of thermal insulation coating. The coating process combines multi-step surface treatment and spraying technology, and uses specific organic acids and functional additives to modify the surface of nanomaterials, thereby significantly improving the thermal insulation performance and bonding strength of the coating. At the same time, through the staged drying and heat treatment process, the microstructure and performance of the coating are further optimized, so that it performs well in terms of thermal insulation, adhesion and durability, meeting the high requirements of aluminum doors and windows for thermal insulation and energy saving.

[0050] Example 1

[0051] A thermal insulation coating process for the surface of aluminum doors and windows is as follows:

[0052] Step 1: Use a spray gun to clean the surface of the aluminum material of the doors and windows to remove the slag and dust on the surface; spray the thermal insulation coating evenly on the surface of the aluminum material of the doors and windows, and the thickness of the first coating is 1mm; then perform segmented drying: first dry at 55°C for 20 minutes, then dry at 70°C for 30 minutes, and finally dry at 90°C for 30 minutes; spray a second time on the basis of the coating after the first drying, the thickness of the second coating is 1mm, first dry at 50°C for 20 minutes, then dry at 70°C for 20 minutes, and finally dry at 90°C for 30 minutes;

[0053] Step 2: Heat the door and window aluminum material dried in step 1 to 110° C. at a heating rate of 1.5° C. / min, keep warm for 10 minutes, and then naturally cool to room temperature, finally forming a heat insulation coating on the surface of the door and window aluminum material.

[0054] The preparation method of the thermal insulation coating is as follows:

[0055] S1, adding 200g of methyl titanium triisopropoxide to 1000g of 60wt% propylene glycol aqueous solution, stirring for 20 minutes, then transferring the mixed solution to a reactor, reacting at 210°C for 24 hours, cooling to room temperature after the reaction, washing with water and anhydrous ethanol for 3 times respectively, placing the product in a vacuum drying oven, and drying at 110°C overnight to obtain a pretreated product;

[0056] S2, dispersing 100 g of the pre-treated product obtained in step S1 in 500 g of phosphate buffer solution, adding 20 g of 3-aminopropyltriethoxysilane, stirring at room temperature for 24 hours, filtering the stirred suspension, collecting the solid product, and obtaining a post-treated product;

[0057] S3. Mix 300g of zirconium nitrate with 400g of lanthanum nitrate, 100g of citric acid, 80g of the post-treated product obtained in step S2, 40g of sodium silicate, 5g of polyvinyl alcohol, 1g of polydimethylsiloxane, 1.2g of sodium hexametaphosphate and 800g of water, stir well to obtain a thermal insulation coating.

[0058] Example 2

[0059] A thermal insulation coating process for the surface of aluminum materials for doors and windows is basically the same as that in Example 1, the only difference being that the preparation method of the thermal insulation coating is different.

[0060] The preparation method of the thermal insulation coating is as follows:

[0061] S1, adding 200g of methyl titanium triisopropoxide to 1000g of 60wt% propylene glycol aqueous solution, stirring for 20 minutes, then transferring the mixed solution to a reactor, reacting at 210°C for 24 hours, cooling to room temperature after the reaction, washing with water and anhydrous ethanol for 3 times respectively, placing the product in a vacuum drying oven, and drying at 110°C overnight to obtain a pretreated product;

[0062] S2, dispersing 100 g of the pre-treated product obtained in step S1 in 500 g of phosphate buffer solution, adding 20 g of 3-glycidyloxypropyltrimethoxysilane, stirring at room temperature for 24 hours, filtering the stirred suspension, collecting the solid product, and obtaining a post-treated product;

[0063] S3. Mix 300g of zirconium nitrate with 400g of lanthanum nitrate, 100g of citric acid, 80g of the post-treated product obtained in step S2, 40g of sodium silicate, 5g of polyvinyl alcohol, 1g of polydimethylsiloxane, 1.2g of sodium hexametaphosphate and 800g of water, stir well to obtain a thermal insulation coating.

[0064] Example 3

[0065] A thermal insulation coating process for the surface of aluminum materials for doors and windows is basically the same as that in Example 1, the only difference being that the preparation method of the thermal insulation coating is different.

[0066] The preparation method of the thermal insulation coating is as follows:

[0067] S1, adding 200g of methyl titanium triisopropoxide to 1000g of 60wt% propylene glycol aqueous solution, stirring for 20 minutes, then transferring the mixed solution to a reactor, reacting at 210°C for 24 hours, cooling to room temperature after the reaction, washing with water and anhydrous ethanol for 3 times respectively, placing the product in a vacuum drying oven, and drying at 110°C overnight to obtain a pretreated product;

[0068] S2, dispersing 100 g of the pre-treated product obtained in step S1 in 500 g of phosphate buffer solution, adding 20 g of dopamine hydrochloride, stirring at room temperature for 24 hours, filtering the stirred suspension, collecting the solid product, and obtaining a post-treated product;

[0069] S3. Mix 300g of zirconium nitrate with 400g of lanthanum nitrate, 100g of citric acid, 80g of the post-treated product obtained in step S2, 40g of sodium silicate, 5g of polyvinyl alcohol, 1g of polydimethylsiloxane, 1.2g of sodium hexametaphosphate and 800g of water, stir well to obtain a thermal insulation coating.

[0070] Example 4

[0071] A thermal insulation coating process for the surface of aluminum materials for doors and windows is basically the same as that in Example 1, the only difference being that the preparation method of the thermal insulation coating is different.

[0072] The preparation method of the thermal insulation coating is as follows:

[0073] S1, adding 200g of methyl titanium triisopropoxide to 1000g of 60wt% propylene glycol aqueous solution, stirring for 20 minutes, then transferring the mixed solution to a reactor, reacting at 210°C for 24 hours, cooling to room temperature after the reaction, washing with water and anhydrous ethanol for 3 times respectively, placing the product in a vacuum drying oven, and drying at 110°C overnight to obtain a pretreated product;

[0074] S2, dispersing 100 g of the pre-treated product obtained in step S1 in 500 g of phosphate buffer solution, adding 20 g of ethylenediamine, stirring at room temperature for 24 hours, filtering the stirred suspension, collecting the solid product, and obtaining a post-treated product;

[0075] S3. Mix 300g of zirconium nitrate with 400g of lanthanum nitrate, 100g of citric acid, 80g of the post-treated product obtained in step S2, 40g of sodium silicate, 5g of polyvinyl alcohol, 1g of polydimethylsiloxane, 1.2g of sodium hexametaphosphate and 800g of water, stir well to obtain a thermal insulation coating.

[0076] Example 5

[0077] A thermal insulation coating process for the surface of aluminum materials for doors and windows is basically the same as that in Example 1, the only difference being that the preparation method of the thermal insulation coating is different.

[0078] The preparation method of the thermal insulation coating is as follows:

[0079] S1, adding 200g of methyl titanium triisopropoxide to 1000g of 60wt% propylene glycol aqueous solution, stirring for 20 minutes, then transferring the mixed solution to a reactor, reacting at 210°C for 24 hours, cooling to room temperature after the reaction, washing with water and anhydrous ethanol for 3 times respectively, placing the product in a vacuum drying oven, and drying at 110°C overnight to obtain a pretreated product;

[0080] S2, dispersing 100 g of the pre-treated product obtained in step S1 in 500 g of phosphate buffer solution, adding 20 g of 3-aminopropyltriethoxysilane, stirring at room temperature for 24 hours, filtering the stirred suspension, collecting the solid product, and obtaining a post-treated product;

[0081] S3. Mix 300g of zirconium nitrate with 400g of lanthanum nitrate, 100g of oxalic acid, 80g of the post-treated product obtained in step S2, 40g of sodium silicate, 5g of polyvinyl alcohol, 1g of polydimethylsiloxane, 1.2g of sodium hexametaphosphate and 800g of water, stir well to obtain a thermal insulation coating.

[0082] Example 6

[0083] A thermal insulation coating process for the surface of aluminum materials for doors and windows is basically the same as that in Example 1, the only difference being that the preparation method of the thermal insulation coating is different.

[0084] The preparation method of the thermal insulation coating is as follows:

[0085] S1, adding 200g of methyl titanium triisopropoxide to 1000g of 60wt% propylene glycol aqueous solution, stirring for 20 minutes, then transferring the mixed solution to a reactor, reacting at 210°C for 24 hours, cooling to room temperature after the reaction, washing with water and anhydrous ethanol for 3 times respectively, placing the product in a vacuum drying oven, and drying at 110°C overnight to obtain a pretreated product;

[0086] S2, dispersing 100 g of the pre-treated product obtained in step S1 in 500 g of phosphate buffer solution, adding 20 g of 3-aminopropyltriethoxysilane, stirring at room temperature for 24 hours, filtering the stirred suspension, collecting the solid product, and obtaining a post-treated product;

[0087] S3. Mix 300 g of zirconium nitrate with 400 g of lanthanum nitrate, 100 g of tartaric acid, 80 g of the post-treated product obtained in step S2, 40 g of sodium silicate, 5 g of polyvinyl alcohol, 1 g of polydimethylsiloxane, 1.2 g of sodium hexametaphosphate and 800 g of water, stir well to obtain a thermal insulation coating.

[0088] Example 7

[0089] A thermal insulation coating process for the surface of aluminum materials for doors and windows is basically the same as that in Example 1, the only difference being that the preparation method of the thermal insulation coating is different.

[0090] The preparation method of the thermal insulation coating is as follows:

[0091] S1, adding 200g of methyl titanium triisopropoxide to 1000g of 60wt% propylene glycol aqueous solution, stirring for 20 minutes, then transferring the mixed solution to a reactor, reacting at 210°C for 24 hours, cooling to room temperature after the reaction, washing with water and anhydrous ethanol for 3 times respectively, placing the product in a vacuum drying oven, and drying at 110°C overnight to obtain a pretreated product;

[0092] S2, dispersing 100 g of the pre-treated product obtained in step S1 in 500 g of phosphate buffer solution, adding 10 g of dopamine hydrochloride and 10 g of ethylenediamine, stirring at room temperature for 24 hours, filtering the stirred suspension, collecting the solid product, and obtaining a post-treated product;

[0093] S3. Mix 300g of zirconium nitrate with 400g of lanthanum nitrate, 100g of citric acid, 80g of the post-treated product obtained in step S2, 40g of sodium silicate, 5g of polyvinyl alcohol, 1g of polydimethylsiloxane, 1.2g of sodium hexametaphosphate and 800g of water, stir well to obtain a thermal insulation coating.

[0094] Comparative Example 1

[0095] A thermal insulation coating process for the surface of aluminum materials for doors and windows is basically the same as that in Example 1, the only difference being that the preparation method of the thermal insulation coating is different.

[0096] The preparation method of the thermal insulation coating is as follows:

[0097] S1, adding 200g of methyl titanium triisopropoxide to 1000g of 60wt% propylene glycol aqueous solution, stirring for 20 minutes, then transferring the mixed solution to a reactor, reacting at 210°C for 24 hours, cooling to room temperature after the reaction, washing with water and anhydrous ethanol for 3 times respectively, placing the product in a vacuum drying oven, and drying at 110°C overnight to obtain a pretreated product;

[0098] S2, dispersing 100 g of the pre-treated product obtained in step S1 in 500 g of phosphate buffer solution, adding 20 g of 3-aminopropyltriethoxysilane, stirring at room temperature for 24 hours, filtering the stirred suspension, collecting the solid product, and obtaining a post-treated product;

[0099] S3. Mix 300g of zirconium nitrate with 400g of lanthanum nitrate, 100g of glycine, 80g of the post-treated product obtained in step S2, 40g of sodium silicate, 5g of polyvinyl alcohol, 1g of polydimethylsiloxane, 1.2g of sodium hexametaphosphate and 800g of water, stir well to obtain a thermal insulation coating.

[0100] Comparative Example 2

[0101] A thermal insulation coating process for the surface of aluminum materials for doors and windows is basically the same as that in Example 1, the only difference being that the preparation method of the thermal insulation coating is different.

[0102] The preparation method of the thermal insulation coating is as follows:

[0103] Mix 300 g of zirconium nitrate with 400 g of lanthanum nitrate, 100 g of citric acid, 80 g of titanium dioxide, 40 g of sodium silicate, 5 g of polyvinyl alcohol, 1 g of polydimethylsiloxane, 1.2 g of sodium hexametaphosphate and 800 g of water, stir well to obtain a thermal insulation coating.

[0104] Test Example 1

[0105] Thermal insulation performance test

[0106] With reference to GB / T 25261-2018 Reflective Insulation Coatings for Buildings, the thermal conductivity (W / (mK)) of the thermal insulation coating on the surface of aluminum doors and windows was tested. The test conditions were a constant temperature of 80°C for the hot surface and 25°C for the cold surface. The specific test data are shown in Table 1.

[0107] Table 1

[0108]

[0109]

[0110] Test Example 2

[0111] With reference to GB / T 25261-2018 "Reflective Thermal Insulation Coatings for Buildings", the thermal insulation coatings on the aluminum surfaces of doors and windows obtained in the examples and comparative examples were tested for the bonding strength (MPa) of the coatings. The test results are shown in Table 2.

[0112] Table 2

[0113] Experimental protocol Bond strength (MPa) Example 1 1.27 Example 2 1.22 Example 3 1.25 Example 4 1.23 Example 5 1.19 Example 6 1.14 Example 7 1.37 Comparative Example 1 1.15 Comparative Example 2 1.01

[0114] It can be seen from the data of test examples 1 to 2 that the thermal insulation performance and bonding strength of the thermal insulation coating on the surface of the door and window aluminum material prepared in Example 7 are the best.

[0115] In the present invention, Example 7 adopts a compounding scheme of dopamine hydrochloride and ethylenediamine, which shows better thermal insulation performance and bonding strength than the surface modifiers (such as 3-aminopropyl triethoxysilane, 3-glycidyl ether oxypropyl trimethoxysilane, dopamine hydrochloride or ethylenediamine) used alone in other embodiments. First, dopamine hydrochloride has a unique self-polymerization characteristic and can form a uniform polymer coating on the surface of the material. This coating can not only enhance the chemical stability and mechanical strength of the material surface, but also form a strong interaction with inorganic nanoparticles and organic matrix through its rich functional groups (such as amino and hydroxyl groups), thereby improving the adhesion and thermal insulation performance of the coating. In addition, the self-polymerization reaction of dopamine can be carried out under mild conditions, avoiding the problem of nanoparticle agglomeration that may be caused by high temperature treatment, and helping to maintain the dispersibility and functionality of nanomaterials. Secondly, ethylenediamine, as an organic small molecule containing two amino groups, can undergo a cross-linking reaction with the hydroxyl groups on the surface of inorganic nanoparticles. This cross-linking effect can further enhance the bonding force between nanoparticles and organic matrix and improve the overall stability of the coating. At the same time, the addition of ethylenediamine can adjust the microstructure of the coating, increase the porosity of the coating, thereby reducing the thermal conductivity of the coating and improving thermal insulation performance. The composite use of dopamine hydrochloride and ethylenediamine realizes the synergistic effect of the two. The self-polymerization characteristics of dopamine provide a good surface modification and adhesion enhancement basis for the coating, and the cross-linking effect of ethylenediamine further optimizes the microstructure and mechanical properties of the coating. This synergistic effect not only improves the thermal insulation performance of the coating, but also significantly enhances the bonding strength between the coating and the substrate, so that Example 7 is superior to other embodiments using a single surface modifier alone in terms of thermal insulation performance and bonding strength.

[0116] In the present invention, Example 1 uses citric acid as an organic acid component, showing thermal insulation performance and bonding strength that are superior to Example 5 (oxalic acid), Example 6 (tartaric acid) and Comparative Example 1 (glycine). This phenomenon can be analyzed from the chemical structure and reaction characteristics of citric acid. First, citric acid is a tricarboxylic acid with three carboxyl (-COOH) functional groups, which enables it to provide more chelating sites during the action process and form more stable complexes with metal ions (such as zirconium nitrate and lanthanum nitrate). This multi-coordinated chelation helps to evenly disperse metal ions, thereby forming a more compact and uniform microstructure in the coating, thereby reducing thermal conductivity and improving thermal insulation performance. In contrast, although oxalic acid and tartaric acid also have good chelating ability, their functional group numbers are relatively small (oxalic acid is a dicarboxylic acid, and tartaric acid is a dihydroxy dicarboxylic acid), and may not be as effective as citric acid in dispersing metal ions and optimizing coating structure. Secondly, citric acid can release more water and carbon dioxide during the action, and the release of these gases helps to form a microporous structure in the coating, further reducing the thermal conductivity of the coating. Although glycine can also participate in the reaction, its chelating ability is weak and it is difficult to form a uniform microporous structure in the coating, so its thermal insulation performance is not as good as citric acid. In terms of bonding strength, the multi-carboxyl structure of citric acid enables it to form more cross-linking points in the coating, enhancing the mechanical properties and adhesion of the coating. In contrast, oxalic acid and tartaric acid have fewer functional groups and form fewer cross-linking points, while glycine lacks sufficient functional groups to form an effective cross-linking network, so the bonding strength is lower.

Claims

1. A thermal insulation coating process for the surface of aluminum doors and windows, characterized in that: The process is as follows: Step 1, use a spray gun to clean the surface of the aluminum material of the doors and windows to remove the slag and dust on the surface; spray the thermal insulation coating evenly on the surface of the aluminum material of the doors and windows, and then perform a segmented drying process: first dry at 50-60°C for 10-30 minutes, then dry at 60-80°C for 20-40 minutes, and finally dry at 80-100°C for 10-40 minutes; spray a second time on the basis of the coating after the first drying, first dry at 40-60°C for 10-30 minutes, then dry at 60-80°C for 10-30 minutes, and finally dry at 80-100°C for 20-40 minutes; Step 2: heating the door and window aluminum material dried in step 1 to 100-120° C., keeping the temperature for 5-20 minutes, and then naturally cooling it to room temperature, finally forming a heat insulation coating on the surface of the door and window aluminum material.

2. The heat-insulating coating process for the surface of aluminum materials for doors and windows as claimed in claim 1 is characterized in that: The thickness of the first coating layer is 0.5-1.5 mm.

3. The heat-insulating coating process for the surface of aluminum materials for doors and windows as claimed in claim 1 is characterized in that: The second coating has a thickness of 0.5 to 1.5 mm.

4. The heat-insulating coating process for the surface of aluminum materials for doors and windows as claimed in claim 1 is characterized in that: The heating rate in step 2 is 1-2°C / min.

5. The heat-insulating coating process for the surface of aluminum materials for doors and windows as claimed in claim 1 is characterized in that: The preparation method of the thermal insulation coating is as follows, in parts by weight: S1, adding 180-220 parts of methyl titanium triisopropoxide to 800-1200 parts of 50-70wt% propylene glycol aqueous solution, stirring for 10-30 minutes, then transferring the mixed solution to a reactor, reacting at 200-220° C. for 10-30 hours, cooling to room temperature after the reaction, washing with water and anhydrous ethanol for 1-3 times respectively, placing the product in a vacuum drying oven, and drying at 100-120° C. overnight to obtain a pretreated product; S2, dispersing 80 to 120 parts of the pre-treated product obtained in step S1 in 400 to 600 parts of a phosphate buffer solution, adding 18 to 22 parts of 3-aminopropyltriethoxysilane, stirring at room temperature for 10 to 30 hours, filtering the stirred suspension, collecting a solid product, and obtaining a post-treated product; S3. Mix 250-350 parts of zirconium nitrate with 350-450 parts of lanthanum nitrate, 80-120 parts of citric acid, 60-100 parts of the post-treated product obtained in step S2, 30-50 parts of sodium silicate, 4-6 parts of film-forming aid, 0.5-2 parts of defoaming agent, 1-1.5 parts of dispersant and 700-900 parts of water, stir well to obtain a thermal insulation coating.

6. The heat-insulating coating process for the surface of aluminum materials for doors and windows as claimed in claim 1 is characterized in that: The preparation method of the thermal insulation coating is as follows, in parts by weight: S1, adding 180-220 parts of methyl titanium triisopropoxide to 800-1200 parts of 50-70wt% propylene glycol aqueous solution, stirring for 10-30 minutes, then transferring the mixed solution to a reactor, reacting at 200-220° C. for 10-30 hours, cooling to room temperature after the reaction, washing with water and anhydrous ethanol for 1-3 times respectively, placing the product in a vacuum drying oven, and drying at 100-120° C. overnight to obtain a pretreated product; S2, dispersing 80 to 120 parts of the pre-treated product obtained in step S1 in 400 to 600 parts of a phosphate buffer solution, adding 8 to 12 parts of dopamine hydrochloride and 8 to 12 parts of ethylenediamine, stirring at room temperature for 10 to 30 hours, filtering the stirred suspension, collecting a solid product, and obtaining a post-treated product; S3. Mix 250-350 parts of zirconium nitrate with 350-450 parts of lanthanum nitrate, 80-120 parts of citric acid, 60-100 parts of the post-treated product obtained in step S2, 30-50 parts of sodium silicate, 4-6 parts of film-forming aid, 0.5-2 parts of defoaming agent, 1-1.5 parts of dispersant and 700-900 parts of water, stir well to obtain a thermal insulation coating.

7. The heat-insulating coating process for the surface of aluminum materials for doors and windows as claimed in claim 5 or 6, characterized in that: The film-forming aid is at least one of hydroxypropyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, polyvinyl alcohol, bentonite and starch.

8. The heat-insulating coating process for the surface of aluminum materials for doors and windows as claimed in claim 5 or 6, characterized in that: The defoaming agent is a silicone defoaming agent.

9. The heat-insulating coating process for the surface of aluminum materials for doors and windows as claimed in claim 5 or 6, characterized in that: The dispersant is a polyphosphate dispersant.

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