A heat insulation coating for renovating an external wall tile of a building and a preparation method thereof

Abstract

The application discloses a heat-insulation coating for renovating building outer wall ceramic tiles and a preparation method thereof, and belongs to the technical field of heat-insulation coatings. According to weight fractions, the heat-insulation coating is composed of the following components: 20-30 parts of aliphatic modified acrylic resin, 3-5 parts of water dispersion of epoxy modified acrylic ester, 2-4 parts of self-made modified aramid fiber, 10-20 parts of hollow glass microbeads, 35 parts of rutile titanium dioxide, 5 parts of far-infrared ceramic powder, 1 part of epoxy silane oligomer, 0.3 part of long-chain linear alcohol, 0.4 part of defoaming agent, 0.8 part of dispersing agent and appropriate amount of water. The unique formula system of the aliphatic modified acrylic resin, the water dispersion of epoxy modified acrylic ester, the self-made modified aramid fiber and the hollow glass microbeads creatively solves the technical problem that the interface adhesion, the sealing property, the heat-insulation performance and the long-term weather resistance are mutually restricted in the existing heat-insulation coating for renovating ceramic tiles, and the core performances are synergistically improved, instead of the compromise optimization for a single performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of thermal insulation coatings, and particularly relates to a thermal insulation coating for renovating building external wall ceramic tiles and a preparation method thereof. BACKGROUND

[0002] According to the first batch of building construction and municipal infrastructure endangering production safety construction process, equipment and material elimination directory. After 2022, all new construction projects of housing construction and infrastructure engineering will not be able to continue to use the construction process of cement mortar paving external wall tiles. As a traditional adhesive for external wall tile paving, cement mortar plays a role in sticking ceramic tiles through the siphon phenomenon generated by the cement hydration reaction. With the rapid advancement of urbanization in China, a large number of existing buildings enter the maintenance and updating cycle; the external wall finish of these buildings mostly uses ceramic tiles, but after long-term exposure to the natural environment, they generally have problems such as aging, cracking, powdering, and even falling off, which not only affects the urban landscape, but also poses a serious threat to public safety.

[0003] The renovation and energy-saving reconstruction of building external walls are important topics in the field of urban renewal and sustainable development. Among them, the finish ceramic tiles used in a large number of existing buildings often have problems such as fading, pollution, cracking, and even partial falling off after years of service, which not only affects the aesthetics of the building, but also brings serious safety hazards. Traditional renovation methods, such as removing old ceramic tiles and re-paving, not only have complicated procedures, high costs, and generate a large amount of construction waste, but also greatly disturb the occupants during construction. Therefore, developing a renovation coating that can be directly applied on the old ceramic tile base has become an urgent need in the industry.

[0004] In recent years, the market has put forward higher requirements for such renovation coatings, that is, while achieving the functions of decoration and protection, it is best to also have excellent thermal insulation performance to reduce building energy consumption.

[0005] The old ceramic tiles of the existing building's external wall are an extremely complex heterogeneous base, with smooth and dense glaze, powdery and loose jointing agent, and potential micro-cracks and pollutants on the surface. To address this challenge, some technical solutions use high-adhesion primer coatings. For example, Chinese patent CN112939544A discloses a single-layer new material for building external walls or floors, which improves the adhesion to the base layer by modifying the cement-based material. However, when such rigid or semi-rigid materials are directly applied to the ceramic tile surface with a large difference in thermal capacity and thermal expansion coefficient, they are difficult to effectively buffer the thermal stress caused by the day-night temperature difference, and are prone to cracking or brittle peeling at the interface under long-term cycling, thereby damaging the long-term sealing and durability of the coating.

[0006] Secondly, in order to pursue stable all-weather thermal insulation performance, the prior art mainly relies on the synergistic effect of high solar reflectance and low thermal conductivity. For example, Chinese patent CN105017872A discloses an external wall thermal insulation and heat preservation functional coating, and CN113861743A discloses a low-cost radiant cooling coating and its preparation method and application. In order to reduce the thermal conductivity, the above-mentioned prior art will add a large amount of low-density thermal insulation fillers such as hollow glass beads or ceramic beads in the coating; however, when the volume concentration of these thermal insulation fillers reaches a level that can significantly reduce the thermal conductivity, it will also seriously damage the continuity of the polymer matrix, resulting in a loose and porous coating, and a sharp decrease in mechanical strength. The loose coating cannot form an effective waterproof sealing layer, which will directly lead to the failure of the resistance to water vapor and negative water pressure; and the coating with insufficient mechanical strength cannot meet the requirements of long-term use in terms of washability, crack resistance and overall weather resistance.

[0007] In addition, in order to resist environmental factors such as ultraviolet degradation, acid rain erosion and freeze-thaw cycles, the external wall renovation coating also needs to ensure excellent weather resistance and long-term durability; therefore, a polymer with extremely stable chemical properties, such as fluorocarbon resin or silicone-modified resin, is usually selected as the film-forming material in the formula; however, such high-performance resins often have extremely low surface energy and fewer polar functional groups in the molecular chain, resulting in weak initial wetting and chemical anchoring ability on inorganic and smooth ceramic tile surfaces, and cannot form good adhesion on complex ceramic tile surfaces. There are also prior arts, such as Chinese patent CN104449117A, which discloses an elastic coating for external wall decoration, which uses an elastic emulsion to give the coating a certain elasticity to cope with thermal stress, but this will sacrifice the stain resistance and long-term durability of the coating, causing the thermal insulation performance of the coating to rapidly decay over time.

[0008] Therefore, in order to fill the technical gap in the market, the present application provides a thermal insulation coating for renovation of building external wall ceramic tiles and a preparation method thereof. SUMMARY

[0009] In order to solve the defects in the above technical solutions, the purpose of the present application is to provide a thermal insulation coating for renovation of building external wall ceramic tiles and a preparation method thereof. The thermal insulation coating for renovation of building external wall ceramic tiles, by weight fraction, consists of the following components, including: 20-30 parts of aliphatic modified acrylic resin, 3-5 parts of epoxy modified acrylic ester water dispersion, 2-4 parts of self-made modified aramid fiber, 10-20 parts of hollow glass beads, 35 parts of rutile titanium dioxide, 5 parts of far infrared ceramic powder, 1 part of epoxy silane oligomer, 0.3 parts of long-chain linear alcohol, 0.4 parts of defoaming agent, 0.8 parts of dispersing agent, and an appropriate amount of water.

[0010] The solid content ratio of the aliphatic modified acrylic resin to the epoxy modified acrylic ester water dispersion is 5:1-7:1;

[0011] The aliphatic modified acrylic resin is a water dispersion, the glass transition temperature of the polymer thereof is 10-40℃; the average particle size of the aliphatic modified acrylic resin water dispersion is 40-100nm;

[0012] The average particle size (D50) of the hollow glass microbead is 20-80μm, and the thermal conductivity coefficient is lower than 0.1 W / (m·K);

[0013] The rutile content of the rutile titanium dioxide is not lower than 98%, and the average particle size is 0.2-0.4μm;

[0014] The average particle size (D50) of the far infrared ceramic powder is 1-10μm;

[0015] The epoxy silane oligomer is an oligomer of γ-glycidyl ether oxypropyl trimethoxysilane;

[0016] The defoaming agent is a mineral oil defoaming agent;

[0017] The dispersant is a polycarboxylic acid sodium salt dispersant.

[0018] Further, the heat insulation coating for building outer wall tile renovation comprises, by weight fraction, the following components: 25 parts of aliphatic modified acrylic resin, 4 parts of epoxy modified acrylic ester water dispersion, 3 parts of self-made modified aramid fiber, 16 parts of hollow glass microbead, 35 parts of rutile titanium dioxide, 5 parts of far infrared ceramic powder, 1 part of epoxy silane oligomer, 0.3 part of long-chain linear alcohol, 0.4 part of defoaming agent, 0.8 part of dispersant, and appropriate amount of water.

[0019] The preparation method of the epoxy modified acrylic ester water dispersion is as follows: in a three-necked flask, add ethylene glycol monomethyl ether and n-butanol as mixed solvents; open the stirring, add bisphenol A type epoxy resin, heat and stir until the epoxy resin is completely dissolved. Then, add 8.61g of methacrylic acid and 0.68g of N,N-dimethyl ethanolamine as esterification catalyst to the solution; heat the reaction system to 105℃, and keep constant temperature for 100-120 minutes. From the beginning of the reaction for 90 minutes, take sample every 10 minutes to detect the acid value of the reaction solution; when the measured acid value is ≤5mgKOH / g, stop heating, and naturally cool to room temperature to obtain solution A;

[0020] In a beaker, add 13g of methyl methacrylate, 21g of butyl acrylate, 4g of acrylic acid, 6g of 2-hydroxyethyl acrylate, 3g of N-methylol acrylamide, and 0.28g of initiator azobisisobutyronitrile, mix well and reserve;

[0021] Subsequently, 50 g of ethanol was added as a reaction solvent in a four-necked flask equipped with a mechanical stirrer, a thermometer, a reflux condenser and a dropping device, and heated to 75°C under stirring; then one fourth of the total amount of the mixture in the beaker was slowly dropped into the flask in 20 minutes for polymerization; the reaction was continued for 30 minutes at 75°C; then the remaining three fourths of the mixture was fully mixed with solution A and dropped into the reaction flask at a constant speed by a dropping pump in 3 hours; after the dropping was completed, the reaction was continued at 75°C for 2 hours. After the reaction was completed, the system was naturally cooled to 50°C, and ammonia water with a mass fraction of 28% was slowly dropped under stirring to adjust the pH value of the product to the range of 8.0-9.0, and then cooled to room temperature and filtered through a 100-200 mesh filter screen to prepare an epoxy-modified acrylate water dispersion.

[0022] The preparation method of the self-made modified aramid fiber is as follows: dopamine hydrochloride is weighed and added into a Tris buffer solution with pH=8.5, and continuous stirring is performed until the dopamine hydrochloride is completely dissolved; then aramid fiber is fully immersed in the reaction mother liquor to ensure that all the fiber is fully infiltrated by the solution; then continuous stirring is performed at room temperature for 2 hours; then silane coupling agent is weighed and slowly and uniformly dropped into the reaction solution; then stirring is continued for 22 hours; after the reaction is completed, the stirring is stopped, the modified fiber is taken out, and is washed with flowing deionized water to remove most of the reaction residues; then the modified fiber is soaked and stirred with anhydrous ethanol, and the washing is repeated for 2-3 times; then the fiber is placed in a vacuum oven at 60°C for drying until the weight is constant, to prepare the self-made modified aramid fiber.

[0023] The self-made modified aramid fiber has a length of 1-5 mm, a diameter of 10-20 μm, and an aspect ratio of 50-500.

[0024] A preparation method of a heat insulation coating for building outer wall tile renovation, in a clean dispersion tank, about 70% of the total water quantity, and part of the defoaming agent and the dispersing agent are added according to the formula amount; then the high-speed dispersion machine is started, and the stirring speed is 400-600 rpm, and the stirring time is 5-10 minutes, so that the auxiliary agent is completely dissolved in the water to form a uniform pre-dispersed liquid. Keep stirring, slowly add rutile titanium dioxide and far infrared ceramic powder to the pre-dispersed liquid. After all the powder is added, the stirring speed is increased to 1200-1600 rpm, and the stirring and dispersion are continued for 20-30 minutes to form a stable and uniform suspension. Then start the low-speed stirring at 200-500 rpm, and slowly add the aliphatic modified acrylic resin, the water dispersion of epoxy modified acrylic ester, the epoxy silane oligomer and the long-chain linear alcohol in sequence; after the addition is completed, continue to stir for 5-10 minutes to ensure uniform mixing. Slowly and evenly sprinkle the hollow glass microbeads into the mixed solution; then slowly add the self-made modified aramid fiber; low-speed stirring for 15-20 minutes until the fiber and the hollow glass microbeads are uniformly dispersed in the system. Finally, add the remaining defoaming agent and dispersing agent, adjust the viscosity of the coating to the preset range by adding an appropriate amount of water, continue to stir at low speed for 10-15 minutes, then stop stirring and stand for defoaming. The final product is filtered through a 100-120 mesh filter to obtain a heat insulation coating for building outer wall tile renovation.

[0025] The final Stormer viscosity of the heat insulation coating for building outer wall tile renovation is uniformly adjusted to 110-120 KU (25 DEG C).

[0026] The present application has the beneficial effects of:

[0027] 1. The technical scheme of the present application overcomes the defects of easy cracking of traditional rigid coatings and insufficient adhesion of flexible coatings in the prior art, ensures that the coating still maintains excellent adhesion and extremely low water absorption under long-term freeze-thaw cycles and humid heat environments, and effectively overcomes the inherent defects of loose coating and strength reduction caused by high filling amount of heat insulation fillers by introducing self-made modified aramid fiber.

[0028] 2. The unique formula system of the aliphatic modified acrylic resin, the water dispersion of epoxy modified acrylic ester, the self-made modified aramid fiber and the hollow glass microbeads creatively solves the technical problem that the interface adhesion, the sealing property, the heat insulation performance and the long-term weather resistance are mutually restricted in the existing tile renovation heat insulation coating, and realizes the synergistic improvement of various core performances, rather than the compromise optimization of a single performance. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a schematic diagram of the surface appearance of the heat insulation coating for building outer wall tile renovation prepared in Example 1 of the present application;

[0030] Figure 2 is a schematic diagram of a multi-color appearance of the heat insulation coating for the renovation of the building outer wall ceramic tile applied in the present application. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with embodiments, the schematic embodiments of the present application and the description thereof are only used to explain the present application, and do not limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or stated range and any other stated value or intermediate value in the stated range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. All publications mentioned in the specification are incorporated by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The citation of any reference in the specification is not intended as an admission that the reference is prior art to the present application.

[0033] Many modifications and variations of the present application described in the specification are possible without departing from the scope or spirit of the present application, which will be apparent to those skilled in the art. Other implementations of the present application will be apparent to those skilled in the art from the specification. The specification and examples of the present application are illustrative only.

[0034] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended terms that are intended to mean including but not limited to.

[0035] The "parts" indicated in the following examples are all weight parts. EMBODIMENTS

[0036] The preparation method of the unmodified aramid fiber is as follows: the aramid fiber is extracted in an acetone solution for 8 h to remove the dirt on the surface of the fiber, washed with distilled water, and dried at 60℃; thus the unmodified aramid fiber is prepared.

[0037] A method for preparing dopamine-modified aramid fibers: 2 g of dopamine hydrochloride is added to 500 mL of Tris buffer solution with pH = 8.5, and stirring is continued until the dopamine hydrochloride is completely dissolved; then 10 g of aramid fibers is completely immersed in the reaction mother liquor, and it is ensured that all the fibers are completely immersed in the solution without air bubbles remaining. Then, after continuous immersion at room temperature for 24 h, it is washed with distilled water and dried at 60°C to constant weight to obtain dopamine-modified aramid fibers.

[0038] A method for preparing silane coupling agent-modified aramid fibers: the unmodified aramid fibers are treated with 30% phosphoric acid solution at 40°C for 5 min; 50 mL of anhydrous ethanol and 100 mL of deionized water are mixed in a beaker, and an appropriate amount of KH560 is added dropwise, and the treated aramid fibers are added, and 3 mL of 20% NaOH solution is added dropwise, and the aramid fibers are fully immersed by ultrasonic oscillation for 30 min, and then the beaker is placed in a water bath heater for constant temperature water bath, and the reaction is slowly stirred for a period of time; the treated aramid fibers are taken out and vacuum filtered, and washed with anhydrous ethanol, and placed in a vacuum drying oven, and dried at 60°C to constant weight to obtain silane coupling agent-modified aramid fibers.

[0039] A method for preparing self-made modified aramid fibers: 2 g of dopamine hydrochloride is added to 500 mL of Tris buffer solution with pH = 8.5, and stirring is continued until the dopamine hydrochloride is completely dissolved; then 10 g of aramid fibers is completely immersed in the reaction mother liquor, and a glass rod can be used to assist pressing, and it is ensured that all the fibers are completely immersed in the solution without air bubbles remaining. Then, stirring is continued at a speed of 300 rpm at room temperature for 2 h; then 1 g of KH560 silane coupling agent is slowly and uniformly added to the above reaction solution; then stirring is continued for 22 h; after the reaction is completed, the stirring is stopped, the modified fibers are taken out and placed in a container, and most of the reaction residues are removed by washing with flowing deionized water; then the modified fibers are soaked and stirred with anhydrous ethanol, and the washing is repeated for 2-3 times, and then the fibers are placed in a vacuum oven at 60°C to dry to constant weight to obtain self-made modified aramid fibers.

[0040] A method for preparing an epoxy-modified acrylic ester water dispersion: 45 g of ethylene glycol monomethyl ether and 45 g of n-butanol are sequentially added to a three-necked flask as a mixed solvent; stirring is started, 45.4 g of bisphenol A type epoxy resin is added, and the temperature is raised and stirring is continued until the epoxy resin is completely dissolved. Then, 8.61 g of methacrylic acid and 0.68 g of N,N-dimethyl ethanolamine as an esterification catalyst are added to the solution; the reaction system is heated to 105°C and kept at this temperature for 100-120 minutes. From the 90th minute of the reaction, the acid value of the reaction solution is detected every 10 minutes; when the measured acid value is ≤5 mgKOH / g, the heating is stopped, and the solution A is obtained by natural cooling to room temperature;

[0041] In a beaker, 13 g of methyl methacrylate, 21 g of butyl acrylate, 4 g of acrylic acid, 6 g of 2-hydroxyethyl acrylate, 3 g of N-hydroxymethyl acrylamide, 0.28 g of initiator azobisisobutyronitrile were added, and after being mixed uniformly, they were used as prepared;

[0042] Subsequently, in a four-necked flask equipped with a mechanical stirrer, a thermometer, a reflux condenser and a dropping device, 50 g of ethanol was added as a reaction solvent, and was heated to 75°C under stirring; then one fourth of the total amount of the mixture in the beaker was slowly dropped into the flask within 20 minutes to carry out polymerization; after 30 minutes of continuous reaction at 75°C; the remaining three fourths of the mixture was mixed with solution A, and was dropped into the reaction flask at a constant speed through a dropping pump within 3 hours; after the dropping was completed, the reaction was continued at 75°C for 2 hours;

[0043] After the reaction was completed, the system was naturally cooled to 50°C, and under stirring, 28% ammonia water was slowly dropped to adjust the pH value of the product to the range of 8.0-9.0, and then was cooled to room temperature; after being filtered through a 100-200 mesh filter screen, an epoxy-modified acrylate water dispersion was prepared.

[0044] A preparation method of a heat insulation coating for building external wall tile renovation, in a clean dispersion tank, about 70% of the total water amount and part of the defoaming agent and dispersant were added according to the formula amount; subsequently, a high-speed dispersing machine was started, and the stirring speed was set to 400-600 rpm for 5-10 minutes, so that the additives were completely dissolved in water to form a uniform pre-dispersion liquid. While keeping stirring, rutile titanium dioxide and far infrared ceramic powder were slowly added to the pre-dispersion liquid. After the powder was completely added, the stirring speed was increased to 1200-1600 rpm, and the stirring and dispersion were continued for 20-30 minutes to form a stable and uniform suspension.

[0045] Subsequently, low-speed stirring was started at 200-500 rpm, and aliphatic modified acrylic resin, epoxy-modified acrylate water dispersion, epoxy silane oligomer and long-chain linear alcohol were slowly added in sequence; after the addition was completed, the stirring was continued for 5-10 minutes to ensure uniform mixing. Hollow glass microbeads were slowly and uniformly scattered into the mixed solution; then, the self-made modified aramid fiber was slowly added; low-speed stirring was continued for 15-20 minutes until the fiber and hollow glass microbeads were uniformly dispersed in the system. Finally, the remaining defoaming agent and dispersant were added, and the viscosity of the coating was adjusted to 110-120 KU (25°C) by adding an appropriate amount of water; then, the stirring was continued at low speed for 10-15 minutes, and then stopped; the final product was filtered through a 100-120 mesh filter screen to prepare a heat insulation coating for building external wall tile renovation.

[0046] The surface appearance of the cured thermal insulation coating is shown in FIG. 1. Figure 1

[0047] The sources of the reagents are shown in Table 1

[0048] Table 1

[0049]

[0050] The specific component formulations of Examples 1-6 are shown in Table 2:

[0051] Table 2

[0052]

[0053] Test Example

[0054] Adhesion test: Referring to GB / T 5210-2006 “Color Paint and Varnish Adhesion Test by Pulling Method”, dry and wet adhesion tests were respectively completed.

[0055] Water absorption test: Referring to JG / T 2090-2011 “Polymer Cement Waterproof Mortar”, the water absorption test of the coating was completed; the dry weight (W1) of the completely cured coating film was measured; it was completely immersed in water for 24 hours, and after taking it out, the surface water was quickly wiped dry with filter paper, and the wet weight (W2) was measured. Water absorption (%) = [(W2-W1) / W1]x100%.

[0056] Thermal insulation performance test: Referring to GB / T 25261-2018 “Reflective Thermal Insulation Coating for Buildings”, the emissivity of the coating in the atmospheric window band of 8-13 μm and the entire infrared band was measured using a Fourier transform infrared spectrometer (FTIR), and the hemispherical emissivity was obtained.

[0057] Thermal insulation effect simulation test: A number of test boxes with built-in thermal insulation materials were made, and the outer surface of the box was pasted with the same old ceramic tiles. The coating was brushed on the surface of the test box, and a blank control box with only ceramic tiles and no coating was reserved. All test boxes were placed side by side in the direct sunlight outdoors. Using a thermocouple and a data logger, the temperature of the outer surface and the inner surface of each box, as well as the ambient temperature, was continuously recorded; finally, the thermal insulation temperature difference ΔT of each example was calculated = blank box inner temperature-test box inner temperature.

[0058] Weather resistance test: Referring to GB / T 1865-2009 “Color Paint and Varnish Artificial Climate Aging and Artificial Radiation Exposure”, the coating sample was placed in a xenon lamp aging test box, and the exposure test was carried out according to the standard set cycle conditions. The total exposure time is usually 1000 hours; after the test is completed, whether the coating appears phenomena such as powdering, cracking, blistering, peeling, etc. is visually evaluated.

[0059] ​Freeze-thaw cycle performance test: refer to the standard JG / T 24-2018 "synthetic resin emulsion sand wall building coating", the painted tile sample is placed in a high-low temperature alternating humidity test chamber. Perform the cycle program: keep at 70℃ for 8 hours, then keep at -20℃ for 16 hours, which is one cycle. After 50 cycles, the sample is taken out and checked for cracking, blistering, peeling and other phenomena. And perform adhesion test, compare with the initial value before freeze-thaw, get the loss rate of bonding strength.

[0060] The performance test results of examples 1-6 are shown in table 3:

[0061] Table 3

[0062]

[0063] The test results of table 3 show that, in comparison example 1 and examples 2, 3, although the conventional styrene-acrylate copolymer emulsion, pure acrylate can also form a film normally, but after 1000h artificial accelerated aging test and freeze-thaw cycle test, examples 2, 3 all appear serious performance attenuation, and the loss rate of bonding strength is also high. Only the aliphatic modified acrylic resin used in the present application, with its unique chemical structure, can provide the coating with the necessary super toughness and stability to resist long-term ultraviolet and thermal stress impact, which is the fundamental prerequisite for long-term durable thermal insulation.

[0064] This shows that even if the person skilled in the art has the motivation to combine acrylic resin with aramid fiber, he cannot foresee that the use of aliphatic modified acrylic resin with this specific chemical structure plays a decisive role in solving the contradiction between long-term weather resistance and thermal stress.

[0065] By comparing the results of comparison example 1 and examples 4, 5, 6, it can be found that the self-made aramid fiber of the present application through synergistic modification, the performance improvement of wet adhesion and low water absorption brought by it is not the technical effect that can be achieved by simply adding aramid fiber without any modification.

[0066] It is side to show that the perfect combination of good dry and wet adhesion and durability exhibited by the technical solution of the present application is not foreseeable by the person skilled in the art by combining any acrylic resin and aramid fiber in the prior art.

[0067] The specific component formula of examples 7-14 is shown in table 4:

[0068] Table 4

[0069]

[0070] The performance test results of examples 7-14 are shown in table 5:

[0071] Table 5

[0072]

[0073] The test results of Table 5 show that when the ratio of aliphatic modified acrylic resin and epoxy modified acrylic ester water dispersion deviates from the interval of 5:1 to 7:1, the core performance of the coating system will drop sharply; such as Example 13, lacking the addition of epoxy modified acrylic ester water dispersion, resulting in insufficient interfacial anchoring force, the coating peels off after freeze-thaw cycle, completely losing the adhesion function; while Example 14, lacking the addition of aliphatic modified acrylic resin, although the initial adhesion is acceptable, but the entire coating system is too brittle, after freeze-thaw cycle, the coating cracks seriously, the bonding strength loss is more than 70%, completely losing long-term durability.

[0074] Through the above experimental data, the creative labor of the present application is reflected in that through systematic experimental exploration, a non-obvious synergistic matching window is found, i.e. the solid content ratio of aliphatic modified acrylic resin and epoxy modified acrylic ester water dispersion is between 5:1 and 7:1. Within this interval, as shown in Examples 8-12, the coating can simultaneously obtain excellent wet adhesion such as greater than 1.80 MPa and extremely low freeze-thaw strength loss rate less than 13%; while the ratio of Example 7 is 8:1, the performance will also drop sharply.

[0075] This shows that the ratio is not a conventional parameter that can be easily determined by conventional orthogonal experiment, but is related to whether the two resins can form a best interpenetrating network structure which can anchor the interface and effectively eliminate stress. Obviously, this requires creative labor.

[0076] The specific component formulations of Examples 15-22 are shown in Table 6:

[0077] Table 6

[0078]

[0079] The performance test results of Examples 15-22 are shown in Table 7:

[0080] Table 7

[0081]

[0082] The test results of Table 7 show that with the increase of the amount of hollow glass microbeads, the thermal insulation temperature difference ΔT of Examples 19 to 22 shows an unexpected trend of first increasing and then decreasing. This shows that after the performance peak, excessive hollow glass microbeads, i.e. Example 22, will cause the collapse of the coating system structure, resulting in serious cracking after freeze-thaw cycle, the bonding strength loss is more than 60%, thereby making the thermal insulation effect in long-term condition decrease sharply.

[0083] And in the hollow microsphere dosage is determined, the amount of self-made modified aramid fiber also has a best interval; If the self-made modified aramid fiber is too little, then the reinforcing network cannot be effectively formed, and the coating will still crack under the freeze-thaw cycle stress; And the self-made modified aramid fiber is too much, then it may be due to dispersion problem, and has a slight negative impact on the thermal insulation performance.

[0084] Therefore, the combination range of the self-made modified aramid fiber and the hollow glass microsphere defined in the present application is not to pursue a single thermal insulation index, but to maintain the comprehensive balance of the coating in the three directions of adhesion, thermal insulation and durability, which fully embodies the achievement of the technical scheme of the present application, and requires creative labor.

[0085] And the thermal insulation coating for building external wall tile renovation of the present application can also add corresponding pigments according to the actual renovation aesthetic requirements when applied, such as Figure 2 As shown, to meet the more extensive renovation needs.

[0086] The above specific embodiments further illustrate the purpose, technical scheme and beneficial effects of the present application, and it should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A thermal barrier coating for renovation of an architectural exterior wall tile, characterized by, The building exterior wall tile renovation heat insulation coating is composed of the following components in parts by weight: 25 parts of aliphatic modified acrylic resin, 4 parts of epoxy modified acrylic ester water dispersion, 3 parts of self-made modified aramid fiber, 16 parts of hollow glass microsphere, 35 parts of rutile titanium dioxide, 5 parts of far infrared ceramic powder, 1 part of epoxy silane oligomer, 0.3 parts of long-chain linear alcohol, 0.4 parts of defoaming agent, 0.8 parts of dispersing agent, and appropriate amount of water. The solid content ratio of the aliphatic modified acrylic resin to the epoxy modified acrylic ester water dispersion is 5:1-7:

1. The self-made modified aramid fiber is prepared by the following method: a dopamine hydrochloride is weighed and added into a Tris buffer solution with pH=8.5, and continuous stirring is performed until the dopamine hydrochloride is completely dissolved; then aramid fiber is completely immersed in the reaction mother liquor to ensure that all the fibers are completely infiltrated by the solution; then continuous stirring is performed at room temperature for 2h; then a silane coupling agent is weighed and slowly and uniformly added into the reaction solution; then continuous stirring is performed for 22h; after the reaction is completed, the stirring is stopped, the modified fiber is taken out, and is placed in a container and washed with flowing deionized water to remove most of the reaction residues; then the modified fiber is soaked and stirred with anhydrous ethanol, and the washing is repeated for 2-3 times, and then the fiber is placed in a vacuum oven at 60 degrees Celsius and dried to constant weight to obtain the self-made modified aramid fiber.

2. The thermal barrier coating for renovation of an external wall tile of a building according to claim 1, characterized by, The building exterior wall tile renovation heat insulation coating is composed of the following components in parts by weight: 25 parts of aliphatic modified acrylic resin, 4 parts of epoxy modified acrylic ester water dispersion, 3 parts of self-made modified aramid fiber, 16 parts of hollow glass microsphere, 35 parts of rutile titanium dioxide, 5 parts of far infrared ceramic powder, 1 part of epoxy silane oligomer, 0.3 parts of long-chain linear alcohol, 0.4 parts of defoaming agent, 0.8 parts of dispersing agent, and appropriate amount of water.

3. The thermal barrier coating for renovation of an external wall tile of a building according to claim 1, characterized by, The aliphatic modified acrylic resin is a water dispersion, and the glass transition temperature of the polymer thereof is 10-40 degrees Celsius; and the average particle size of the aliphatic modified acrylic resin water dispersion is 40-100nm.

4. The thermal barrier coating for renovation of an external wall tile of a building according to claim 1, characterized by, The average particle size D50 of the hollow glass microsphere is 20-80μm, and the thermal conductivity coefficient is lower than 0.1 W / (m·K).

5. A thermal barrier coating for the renovation of building facade ceramic tiles according to any of claims 1 to 4, characterized in that, The preparation method of the epoxy-modified acrylate water dispersion includes the following steps: adding 70% of the total amount of water and part of the defoaming agent and dispersant into a clean dispersion tank according to the formula; then starting the high-speed dispersion machine and stirring for 5-10 minutes to make the additives completely dissolved in water; keeping stirring, slowly adding the rutile titanium dioxide and far-infrared ceramic powder into the pre-dispersion liquid; after the powder is completely added, continue stirring and dispersing for 20-30 minutes to form a stable and uniform suspension; then starting the low-speed stirring, sequentially adding the aliphatic modified acrylic resin, the epoxy-modified acrylate water dispersion, the epoxy silane oligomer and the long-chain linear alcohol; after adding, continue stirring for 5-10 minutes; slowly and uniformly scattering the hollow glass microbeads into the mixed liquid; and slowly adding the self-made modified aramid fiber; low-speed stirring for 15-20 minutes until the fiber and the hollow glass microbeads are uniformly dispersed in the system; finally adding the remaining defoaming agent and dispersant, adjusting the viscosity of the coating to the preset range by adding an appropriate amount of water, and continuing to stir at low speed for 10-15 minutes, then stopping stirring and standing for defoaming; filtering the final product through a 100-120 mesh filter to prepare a thermal insulation coating for building external wall tile renovation.

6. The thermal insulation coating for building external wall tile renovation according to claim 1, wherein the self-made modified aramid fiber has a length of 1-5 mm, a diameter of 10-20 μm, and an aspect ratio of 50-500.

7. The method for preparing a thermal insulation coating for renovation of an external wall tile of a building according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: in a clean dispersion tank, adding 70% of the total amount of water and part of the defoaming agent and dispersant according to the formula; then starting the high-speed dispersion machine and stirring for 5-10 minutes to make the additives completely dissolved in water; keeping stirring, slowly adding the rutile titanium dioxide and far-infrared ceramic powder into the pre-dispersion liquid; after the powder is completely added, continue stirring and dispersing for 20-30 minutes to form a stable and uniform suspension; then starting the low-speed stirring, sequentially adding the aliphatic modified acrylic resin, the epoxy-modified acrylate water dispersion, the epoxy silane oligomer and the long-chain linear alcohol; after adding, continue stirring for 5-10 minutes; slowly and uniformly scattering the hollow glass microbeads into the mixed liquid; and slowly adding the self-made modified aramid fiber; low-speed stirring for 15-20 minutes until the fiber and the hollow glass microbeads are uniformly dispersed in the system; finally adding the remaining defoaming agent and dispersant, adjusting the viscosity of the coating to the preset range by adding an appropriate amount of water, and continuing to stir at low speed for 10-15 minutes, then stopping stirring and standing for defoaming; filtering the final product through a 100-120 mesh filter to prepare a thermal insulation coating for building external wall tile renovation.

8. The method for preparing a heat-insulating coating for renovating building exterior wall ceramic tiles according to claim 7, characterized in that, The Stomer viscosity of the thermal insulation coating for building external wall tile renovation is uniformly adjusted to 110-120 KU, and the determination temperature is 25°C.

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