Waterproof breathable coating as well as preparation method and construction method thereof

Abstract

The invention discloses a waterproof breathable coating which comprises a component A, a component B and a component C. The mass ratio of the component A to the component B to the component C is (4-6): 1: (23-25). The component A is prepared from the following components in parts by mass: 500 to 700 parts of water-based hydroxy acrylic acid dispersion, 100 to 200 parts of water, 50 to 100 parts of lithium silicate, 2 to 4 parts of dispersing agent, 1 to 3 parts of wetting agent, 1 to 3 parts of preservative, 1 to 3 parts of defoaming agent, 2 to 4 parts of cellulose, 50 to 100 parts of titanium dioxide, 2 to 4 parts of thickening agent, 10 to 20 parts of ethylene glycol, 1 to 2 parts of pH regulator and 0 to 100 parts of water-based color paste; the component B comprises the following components in parts by mass: 950-990 parts of a water dispersible isocyanate curing agent and 10-50 parts of a diluent; the component C is prepared from the following components in parts by mass: 200 to 300 parts of quartz powder, 100 to 300 parts of high-alumina cement, 300 to 400 parts of quartz sand and 1 to 3 parts of retarder. In addition, the invention further discloses a preparation method and a construction method of the waterproof and breathable coating. The ceramic tile outer wall renovating interface adhesion requirement can be met, and meanwhile the problems of water resistance, breathability, tedious construction, saltpetering, whitening and the like of an outer wall are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and particularly relates to a waterproof and breathable coating, a preparation method thereof, and a construction method thereof. Background Art

[0002] A ceramic tile exterior wall is mainly composed of a concrete base layer, an adhesive mortar, ceramic tiles, and a joint filler, and is widely used in modern buildings due to its durability and high-class decorative effect. However, as the building is used year by year, affected by factors such as structural stress, differences in material shrinkage characteristics, and self-strain differences caused by alternating temperature and humidity, problems such as hollowing, cracking, and deformation are inevitable in the ceramic tile exterior wall. At the same time, the adhesive mortar ages year by year, the adhesive force decreases, and ceramic tile shedding problems will also occur. Therefore, in order to extend the service life of the building, ensure the safety of building use, and improve the problem of poor wall appearance caused by factors such as dirt and aging of the ceramic tile exterior wall, it is necessary to repair the ceramic tile exterior wall.

[0003] The current repair methods mainly include the following two:

[0004] Firstly, without changing the ceramic tile decoration style, only the ceramic tile surface is renovated and recolored. During the repair, the ceramic tile surface needs to be cleaned, and then 1-2 coats of transparent waterproof coating or ceramic tile color-changing paint are applied. After applying the transparent waterproof coating, the original color of the ceramic tile surface can be maintained, making the ceramic tile surface newer and more lustrous. After applying the ceramic tile color-changing paint, the original color of the ceramic tile surface can be changed. However, this repair method requires that the adhesive force of the ceramic tiles is intact, without hollowing, cracks, or peeling, and has high requirements for the repair object. Moreover, after the repair is completed, the air permeability of the ceramic tiles will be reduced, resulting in the inability of water vapor in the wall to be discharged. In the long run, the coating is likely to bulge and peel off.

[0005] Secondly, it is necessary to remove the damaged ceramic tiles, inject grout for anchoring at the hollow part of the ceramic tiles, then use waterproof and crack-resistant mortar to level the ceramic tile surface, and hang a crack-resistant grid cloth for reinforcement. After the reinforcement, a coating process is carried out, and primers, intermediate paints, topcoats, and other coatings are applied. This repair method can randomly change the original appearance of the building, but the types of coatings used are more, the construction is cumbersome, and under the coverage of multiple coatings, the air permeability of the wall is seriously reduced, and the water remaining in the wall cannot be discharged either, which is easy to penetrate into the inner wall, resulting in the bulging, peeling, and mildewing of the inner wall paint.

[0006] Since most of the current ceramic tile surfaces are glazed, with high density and extremely low water absorption rate, it is extremely difficult for most single-component waterborne coatings to adhere to their surfaces. Therefore, no matter which method is used to repair the ceramic tile exterior wall, there are high requirements for the adhesion of the coating, which is also the main technical problem considered in the existing coatings for ceramic tile renovation.

[0007] However, there is no feasible solution to the problem of the air permeability of the repaired wall. For many old walls that need to be renovated, there are rain leakage problems at the joints such as the roof and window sills, the moisture content of the wall is relatively high, and it is obvious that water vapor is difficult to discharge after renovation with existing coatings and renovation methods, and problems such as bulging and peeling are likely to occur. Summary of the Invention

[0008] The purpose of the present invention is to provide a waterproof and breathable coating, its preparation method and construction method to solve the interface adhesion problem of the renovation of the ceramic tile exterior wall, and at the same time improve the waterproof and breathable problems and the problem of cumbersome construction.

[0009] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0010] A waterproof and breathable coating includes component A, component B and component C, and the mass ratio of component A, component B and component C is (4-6):1:(23-25);

[0011] Component A includes, by mass parts: 500-700 parts of waterborne hydroxyl acrylic dispersion, 100-200 parts of water, 50-100 parts of lithium silicate, 2-4 parts of dispersant, 1-3 parts of wetting agent, 1-3 parts of preservative, 1-3 parts of defoaming agent, 2-4 parts of cellulose, 50-100 parts of titanium dioxide, 2-4 parts of thickener, 10-20 parts of ethylene glycol, 1-2 parts of pH regulator, 0-100 parts of waterborne color paste;

[0012] Component B includes, by mass parts: 950-990 parts of water-dispersible isocyanate curing agent, 10-50 parts of diluent;

[0013] Component C includes, by mass parts: 200-300 parts of quartz powder, 100-300 parts of high alumina cement, 300-400 parts of quartz sand, 1-3 parts of retarder.

[0014] Further, the hydroxyl value range of the waterborne hydroxyl acrylic dispersion is 3-4%.

[0015] Preferably, the diluent is propylene glycol methyl ether acetate, the mesh number of the quartz powder is 100-200 mesh, the quartz sand is one or a combination of quartz sand of 80-120 mesh, 40-80 mesh and 20-40 mesh, and the retarder is sodium tetraborate decahydrate.

[0016] The present invention also provides a preparation method of a waterproof and breathable coating. The method first prepares component A, component B and component C respectively, and then mixes the prepared component A, component B and component C evenly according to the ratio to obtain the waterproof and breathable coating, wherein:

[0017] Preparation of Component A: Water, dispersant, wetting agent, preservative and defoamer are stirred and dispersed at the first rotation speed; then cellulose, pH regulator and titanium dioxide are added and stirred and dispersed at the second rotation speed; finally, waterborne hydroxyl acrylate dispersion, lithium silicate, ethylene glycol and thickener are added and stirred and dispersed at the third rotation speed to obtain Component A;

[0018] Preparation of Component B: Water-dispersible isocyanate curing agent and diluent are stirred and dispersed at the fourth rotation speed to obtain Component B;

[0019] Preparation of Component C: Quartz powder, high-alumina cement, quartz sand and retarder are mixed and stirred evenly to obtain Component C.

[0020] Preferably, the first rotation speed is 400 - 500 revolutions per minute, the second rotation speed is 1200 - 1800 revolutions per minute, the third rotation speed is 800 - 1000 revolutions per minute, and the fourth rotation speed is 400 - 500 revolutions per minute.

[0021] The present invention also provides a construction method of a waterproof and breathable coating, including the following steps: S1. Clean the old decorative layer to be renovated; S2. Apply the waterproof and breathable coating on the surface of the old decorative layer to form a waterproof and breathable coating.

[0022] Furthermore, step S1 further includes: injecting and reinforcing the hollow and loose parts of the old decorative layer with grouting anchor bolts; step S2 further includes: laying a grid cloth or a crack-resistant felt when applying the waterproof and breathable coating.

[0023] Furthermore, step S2 specifically includes:

[0024] S21. Apply the first coat of the waterproof and breathable coating on the surface of the old decorative layer to form a first coating;

[0025] S22. Insert porous breathable columns on the first coating, the positions of the porous breathable columns corresponding to the splicing gaps of the old decorative layer. The porous breathable columns have multiple breathable channels for water vapor to pass through inside. The inner ports of the breathable channels face the old decorative layer, and the outer ports can intercept water droplets. A temporary protection member is provided at the outer end of the porous breathable column, and the temporary protection member closes the outer ports of the breathable channels;

[0026] S23. Wait for the first coating to dry, and then apply the second coat of the waterproof and breathable coating on the first coating to form a second coating;

[0027] S24. Remove the temporary protection member.

[0028] Furthermore, when the porous breathable columns are made of hydrophilic materials, both the inner and outer ends of the porous breathable columns are hydrophobic ends treated by hydrophobic treatment.

[0029] Preferably, the porous air-permeable column is a ceramic column or a plastic column. The diameter of the porous air-permeable column is 1-5 mm, and the pore diameter of the air-permeable channel is 5-30 μm. The inner end and the outer end of the porous air-permeable column are subjected to hydrophobic treatment by dip-coating with solvent-free silane, and the dip-coating depth of the solvent-free silane is 0.5-1.5 mm.

[0030] The present invention has the following beneficial effects:

[0031] 1. The present invention utilizes the organic bonding of the waterborne hydroxyacrylate dispersion and the water-dispersible isocyanate curing agent and the inorganic bonding of the high-alumina cement and lithium silicate. The organic-inorganic synergistic effect enables the coating to have a relatively high interfacial bonding strength, which can meet the interfacial adhesion requirements for the renovation of the ceramic tile exterior wall, and the coating adhesion is firm.

[0032] 2. The coating of the present invention has multiple functions. When the coating is used during construction, it can simultaneously solve the problems of interfacial adhesion, leveling, waterproofing, decoration, and reinforcement in the renovation of the ceramic tile exterior wall, simplify the construction, and the coating is equipped with a breathable material. The renovated coating has good breathability, can block the penetration of external rainwater into the wall, and at the same time allows the moisture inside the wall to be discharged outward in the form of water vapor, solving the breathability problem after the renovation of the ceramic tile exterior wall.

[0033] 3. The coating of the present invention is equipped with high-alumina cement. Utilizing the hydraulicity of the cement, strength can be established at the thick-coated parts of the coating such as the ceramic tile joints without complete evaporation of water, which is beneficial to reducing the strength establishment time difference between the thick-coated parts and the thin-coated parts of the coating and improving the cracking phenomenon caused by inconsistent drying shrinkage at the two places. In addition, using high-alumina cement instead of ordinary Portland cement, there is no calcium hydroxide in the hydrate, which can avoid the phenomenon of efflorescence and whitening on the exterior wall surface.

[0034] 4. Porous air-permeable columns are inserted during the construction of the present invention. The porous air-permeable columns have air-permeable channels that can communicate the inside and outside of the wall, and can significantly enhance the breathability of the exterior wall and discharge the accumulated water vapor inside the wall. Description of the Drawings

[0035] Figure 1 It is a schematic structural diagram of the ceramic tile exterior wall before renovation.

[0036] Figure 2 It is a schematic structural diagram (I) of the renovated ceramic tile exterior wall of the present invention.

[0037] Figure 3 It is a schematic structural diagram (II) of the renovated ceramic tile exterior wall of the present invention.

[0038] Figure 4 It is a schematic structural diagram (I) of the porous air-permeable column of the present invention.

[0039] Figure 5 Schematic diagram (II) of the porous breathable column structure of the present invention.

[0040] Figure 6 Schematic diagram of the insertion of the porous breathable column of the present invention.

[0041] Description of main component symbols:

[0042] 1. Concrete base layer; 2. Bonding mortar layer; 3. Old decorative layer; 31. Ceramic tile layer; 32. Grout layer; 4. Waterproof and breathable coating; 41. First coating; 42. Second coating; 5. Grouting anchor; 6. Crack-resistant felt; 7. Porous breathable column; 71. Breathable channel; 711. Inner port; 712. Outer port; 8. Temporary protection piece; L. Dipping depth. Specific implementation mode

[0043] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation modes.

[0044] Example 1

[0045] A waterproof and breathable coating, comprising component A, component B and component C, and the mass ratio of component A, component B and component C is (4 - 6):1:(23 - 25), preferably the mass ratio is 5:1:24.

[0046] Component A includes, by mass parts: 500 - 700 parts of aqueous hydroxyl acrylic dispersion, 100 - 200 parts of water, 50 - 100 parts of lithium silicate, 2 - 4 parts of dispersant, 1 - 3 parts of wetting agent, 1 - 3 parts of preservative, 1 - 3 parts of defoaming agent, 2 - 4 parts of cellulose, 50 - 100 parts of titanium dioxide, 2 - 4 parts of thickener, 10 - 20 parts of ethylene glycol, 1 - 2 parts of PH regulator, 0 - 100 parts of aqueous color paste.

[0047] Component B includes, by mass parts: 950 - 990 parts of water-dispersible isocyanate curing agent, 10 - 50 parts of diluent.

[0048] Component C includes, by mass parts: 200 - 300 parts of quartz powder, 100 - 300 parts of high-aluminum cement, 300 - 400 parts of quartz sand, 1 - 3 parts of retarder.

[0049] In Component A, the hydroxyl value range of the aqueous hydroxyl acrylic dispersion is 3-4%, which can react with the curing agent in Component B to form an organic coating film; lithium silicate can improve the durability of high-alumina cement and is outstanding in terms of resistance to chloride ion penetration, sulfate erosion, and frost resistance; the dispersant is Dow Chemical 731A; the wetting agent is Dow Chemical BD-405; the preservative is Thor EG-CLF; the cellulose is HPMC75000S; the titanium dioxide is rutile titanium white; the thickener is Dow Chemical RM-8W; the pH regulator is Thorway AN2200; the aqueous color paste is added and adjusted according to color requirements or not added.

[0050] In Component B, the water-dispersible isocyanate curing agent is selected from Wanhua 161; the diluent is propylene glycol methyl ether acetate.

[0051] In Component C, the quartz powder is selected from the products of Lingshou County Yunshi Mineral Products Processing Factory, and its mesh number is 100-200 meshes; the quartz sand is selected according to the decorative appearance requirements and can be one or several combinations of 80-120 mesh quartz sand, 40-80 mesh quartz sand, and 20-40 mesh quartz sand; the high-alumina cement is Lafarge's Secar71; the retarder is sodium tetraborate decahydrate.

[0052] The performance of this coating simultaneously meets JC / T1004-2017 "Ceramic Tile Jointing Agent", JC / T984-2011 "Polymer Cement Waterproof Mortar", and JG / T24-2018 "Standard for Synthetic Resin Emulsion Sand Wall-Type Architectural Coatings", and has a three-in-one effect. Therefore, when used for the renovation of the exterior wall of ceramic tiles, only applying this coating can simultaneously solve the problems of interface adhesion, leveling, waterproofing, decoration, and reinforcement, which can simplify the construction of the renovation of the exterior wall of ceramic tiles and save labor.

[0053] Based on the organic bonding of the aqueous hydroxyl acrylic dispersion and the water-dispersible isocyanate curing agent and the inorganic bonding of the high-alumina cement and lithium silicate, this coating has a relatively high interfacial bonding strength, and the formed coating can firmly adhere to the ceramic tile surface.

[0054] In the coating, high-alumina cement is used instead of ordinary Portland cement for bonding. There is no calcium hydroxide in its hydrate, which can avoid the phenomenon of alkali efflorescence and whitening on the exterior wall surface after brushing. Moreover, the formed coating itself has waterproofness and breathability. It can not only prevent surface water (such as rainwater) from seeping into the wall, but also allow water vapor to pass through. The water vapor transmission rate is tested according to JG / T309-2011 "Determination and Classification of Water Vapor Transmission Rate of Exterior Wall Coatings", and is 120 V / g(m2.d), reaching the intermediate standard.

[0055] Moreover, by utilizing the hydraulicity of cement, strength can be established at the thick-coated part of the coating without complete evaporation of water, which helps to reduce the time difference in strength establishment between the thick-coated part and the thin-coated part of the coating, and improve the cracking phenomenon caused by inconsistent drying shrinkage at the two places. For example, on the exterior wall of ceramic tiles, the depth of the gap between tiles is usually 0.5 - 1 cm, and the thickness of the coating on the tile surface is usually 0.1 - 0.2 cm. When renovating, the coating thickness difference at the two places is relatively large. If conventional coatings are used, coating cracking is likely to occur, but the coating of the present invention can well improve this phenomenon.

[0056] Refer to JC / T1004 - 2017 "Ceramic Tile Joint Filler" for the basic performance of cement-based joint fillers, JC / T984 - 2011 "Polymer Cement Waterproof Mortar", and JG / T24 - 2018 "Synthetic Resin Emulsion Sand-textured Architectural Coatings" for external use to test the performance of this coating. The test results are shown in the following table, and it can be seen that all meet the requirements of each standard.

[0057]

[0058]

[0059] Example Two

[0060] The present invention also provides a preparation method of a waterproof and breathable coating. First, components A, B, and C are respectively prepared, and then the prepared components A, B, and C are mixed evenly according to the ratio to obtain the waterproof and breathable coating in Example One above. Among them:

[0061] The preparation steps of component A are as follows:

[0062] A1. Add water, dispersant, wetting agent, preservative, and defoamer into a disperser, and stir and disperse them at a first rotation speed of 400 - 500 revolutions per minute.

[0063] A2. Keep the first rotation speed, and then sequentially add cellulose, PH regulator, and titanium dioxide into the disperser, and stir and disperse them at a second rotation speed of 1200 - 1800 revolutions per minute.

[0064] A3. Adjust the rotation speed of the disperser to a third rotation speed of 800 - 1000 revolutions per minute, and finally sequentially add waterborne hydroxyl acrylic dispersion, lithium silicate, ethylene glycol, and thickener into the disperser, and stir and disperse them at the third rotation speed. After completion, component A is obtained.

[0065] The preparation of component B: Add water-dispersible isocyanate curing agent and diluent into a disperser, and stir and disperse them at a fourth rotation speed of 400 - 500 revolutions per minute. After completion, component B is obtained.

[0066] Preparation of Component C: Put quartz powder, high-alumina cement, quartz sand and retarder into a powder stirring device, mix them together and stir evenly. After completion, Component C is obtained.

[0067] The waterproof and breathable coating obtained based on this preparation method has multiple properties and is especially suitable for the renovation of exterior walls of ceramic tiles.

[0068] Example 3

[0069] Based on the above Example 1, the present invention also provides a construction method for a waterproof and breathable coating, which mainly includes the following two steps: S1. Clean the old decorative layer 3 to be renovated; S2. Apply the waterproof and breathable coating on the surface of the old decorative layer 3 to form a waterproof and breathable coating 4.

[0070] Taking the application to the renovation of exterior walls of ceramic tiles as an example, the structure of the exterior wall of ceramic tiles before renovation is as Figure 1 shown, which includes a concrete base layer 1, an adhesive mortar layer 2, a ceramic tile layer 31 and a joint filler layer 32. The joint filler layer 32 is filled in the splicing gaps between the ceramic tiles of the ceramic tile layer 31.

[0071] When using this construction method to repair the exterior wall of ceramic tiles, the old decorative layer 3 to be cleaned includes the above-mentioned ceramic tile layer 31 and joint filler layer 32. Generally, the old ceramic tiles are firmly pasted. As Figure 2 shown, when cleaning, the dust, oil stains, attachments, etc. on the surface of the ceramic tiles need to be removed completely, and the aging joint filler layer 32 needs to be removed to avoid affecting the firmness of the coating. The formed waterproof and breathable coating 4 can cover the old decoration, fill the gaps between the ceramic tiles and other concave parts, and at the same time achieve the purposes of leveling, strengthening, decoration, waterproofing and breathability.

[0072] As Figure 3 shown, if there is a phenomenon of hollow ceramic tiles, after cleaning the old decorative layer 3, it is also necessary to use grouting anchor bolts 5 to grout and reinforce the hollow and loose parts of the ceramic tiles to enhance the adhesion of the ceramic tiles and reduce the risk of ceramic tile shedding; at the same time, when applying the waterproof and breathable coating, lay a fiberglass mesh or crack-resistant felt 6 to correspondingly improve the strength and crack resistance of the coating.

[0073] Generally, the coating needs to be applied in 2 coats, and the formed waterproof and breathable coating 4 has excellent breathability. However, when the coating is applied to the renovation of exterior walls of ceramic tiles, due to the extremely low breathability of the ceramic tile surface, most of the water vapor in the wall can only be discharged through the splicing gaps of the ceramic tiles. Affected by this, the total breathable area is small, and the breathable effect of relying solely on the waterproof and breathable coating 4 is relatively limited. In this regard, the present invention adds a porous breathable device as Figure 2-5 shown during the brushing of the waterproof and breathable coating to accelerate the discharge of water vapor. The corresponding step S2 specifically includes:

[0074] S21. Apply the first coat of waterproof and breathable coating on the surface of the old decorative layer 3 for leveling to form the first coating 41.

[0075] S22. As Figure 6 shown, insert the porous breathable column 7 on the first coating 41. The porous breathable column 7 corresponds to the position of the splicing gap of the old decorative layer 3, that is, it corresponds to the main part of the tile exterior wall for air permeability, and is correspondingly inserted into the first coating 41 between each tile.

[0076] The diameter of the porous breathable column 7 is 1 - 5 mm, preferably 2 mm, to fit the splicing gap, and the length is selected according to the depth of the splicing gap, which can be 5 mm - 20 mm, preferably 10 mm.

[0077] The porous breathable column 7 has multiple breathable channels 71 inside. The inner port 711 of the breathable channel 71 faces the old decorative layer 3, and the outer port 712 faces away from the old decorative layer 3. Generally, the diameter of water vapor molecules is about 4×10 -4 μm, and the diameter of water droplets is about 80 μm. Therefore, controlling the aperture of the breathable channel 71 to be larger than the diameter of water vapor molecules and smaller than the diameter of water droplets can play a role in allowing water vapor to pass through and intercepting water droplets. Preferably, the aperture of the breathable channel 71 is controlled within 5 - 30 μm.

[0078] An exposed temporary protection member 8 is provided at the outer end of the porous breathable column 7. Through this temporary protection member 8, the outer port 712 of the breathable channel 71 can be closed to prevent the outer port 712 from being blocked when applying the coating.

[0079] S23. Wait for the first coating 41 to dry, and then apply the second coat of waterproof and breathable coating on the first coating 41 and arrange the shape according to the required effect to form the second coating 42.

[0080] S24. Remove the temporary protection member 8 to expose the outer ports 712 of the breathable channels 71 in the porous breathable column 7 and make the breathable channels 71 unblocked.

[0081] According to the water content of the old wall, the number of the porous breathable columns 7 that can be embedded per square meter is 10 - 20. Through the porous breathable column 7, it can guide and accelerate the discharge of water vapor in the wall, improve the overall air permeability of the tile exterior wall, and even the smallest water droplets cannot enter the breathable channel 71 due to the surface tension without applying pressure, which can prevent external clear water from seeping into the wall through the porous breathable column 7.

[0082] However, when the porous air-permeable column 7 is made of a hydrophilic material, water droplets may enter the wall through the porous air-permeable column 7 by infiltration. In this regard, the outer end of the porous air-permeable column 7 needs to be a hydrophobic end treated by hydrophobic treatment to increase the surface tension of the outer end through hydrophobic treatment, block the infiltration of external water droplets into the wall, and at the same time reduce the probability of water droplets entering the outer port 712 of the air-permeable channel 71 under pressure. Similarly, since the porous air-permeable column 7 is inserted when the first coating 41 is not dry, it is also necessary to pre-treat the inner end of the porous air-permeable column 7 by hydrophobic treatment to avoid wet paint blocking the inner port 711 of the air-permeable channel 71.

[0083] In this embodiment, the inner end and the outer end of the porous air-permeable column 7 are treated by hydrophobic treatment by dip-coating with solvent-free silane. The solvent-free silane is selected as Wacker BS4004 from Germany, and the dip-coating depth L is 0.5-1.5 mm. After the hydrophobic treatment, the middle part of the outer wall surface of the porous air-permeable column 7 is still a hydrophilic interface, which will not affect the combination with the paint. The porous air-permeable column 7 can be a ceramic column or a plastic column, but considering from the perspectives of aging resistance and paint fusion degree, it is preferably a ceramic column, which has high strength and stiffness while having the air-permeable channel 71.

[0084] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, those skilled in the art should understand that various changes in form and details can be made to the present invention without departing from the spirit and scope of the present invention defined by the appended claims, and all such changes are within the protection scope of the present invention.

Claims

1. A waterproof and breathable coating, comprising component A, component B and component C, characterized in that: The mass ratio of component A, component B and component C is (4 - 6):1:(23 - 25); Component A, by mass parts, includes: 500 - 700 parts of aqueous hydroxy acrylic dispersion, 100 - 200 parts of water, 50 - 100 parts of lithium silicate, 2 - 4 parts of dispersant, 1 - 3 parts of wetting agent, 1 - 3 parts of preservative, 1 - 3 parts of defoaming agent, 2 - 4 parts of cellulose, 50 - 100 parts of titanium dioxide, 2 - 4 parts of thickener, 10 - 20 parts of ethylene glycol, 1 - 2 parts of pH regulator, 0 - 100 parts of aqueous color paste; Component B, by mass parts, includes: 950 - 990 parts of water - dispersible isocyanate curing agent, 10 - 50 parts of diluent; Component C, by mass parts, includes: 200 - 300 parts of quartz powder, 100 - 300 parts of high - alumina cement, 300 - 400 parts of quartz sand, 1 - 3 parts of retarder.

2. The waterproof and breathable coating according to claim 1, characterized in that: The hydroxyl value range of the aqueous hydroxy acrylic dispersion is 3 - 4%.

3. The waterproof and breathable coating according to claim 1, characterized in that: The diluent is propylene glycol methyl ether acetate, the mesh number of the quartz powder is 100 - 200 mesh, the quartz sand is one or a combination of quartz sand with 80 - 120 mesh, 40 - 80 mesh and 20 - 40 mesh, and the retarder is sodium tetraborate decahydrate.

4. The preparation method of the waterproof and breathable coating according to any one of claims 1 - 3, characterized in that: First, prepare component A, component B and component C respectively, and then mix the prepared component A, component B and component C evenly according to the ratio to obtain the waterproof and breathable coating, where: Preparation of component A: Stir and disperse water, dispersant, wetting agent, preservative and defoaming agent at the first rotation speed; then add cellulose, pH regulator and titanium dioxide, and stir and disperse at the second rotation speed; finally, add aqueous hydroxy acrylic dispersion, lithium silicate, ethylene glycol and thickener, and stir and disperse at the third rotation speed to obtain component A; Preparation of component B: Stir and disperse the water - dispersible isocyanate curing agent and diluent at the fourth rotation speed to obtain component B; Preparation of component C: Mix and stir evenly quartz powder, high - alumina cement, quartz sand and retarder to obtain component C.

5. The preparation method of the waterproof and breathable coating according to claim 4, characterized in that: The first rotation speed is 400 - 500 revolutions per minute, the second rotation speed is 1200 - 1800 revolutions per minute, the third rotation speed is 800 - 1000 revolutions per minute, and the fourth rotation speed is 400 - 500 revolutions per minute.

6. The construction method of the waterproof and breathable coating according to any one of claims 1-3, characterized in that It includes the following steps: S1. Clean the old decorative layer to be renovated; S2. Apply the waterproof and breathable coating on the surface of the old decorative layer to form a waterproof and breathable coating.

7. The construction method of the waterproof and breathable coating according to claim 6, characterized in that: Step S1 further includes: Injecting and reinforcing the hollow and loose parts of the old decorative layer with grouting anchor bolts; Step S2 further includes: Laying a fiberglass mesh or crack - resistant felt when applying the waterproof and breathable coating.

8. The construction method of the waterproof and breathable coating according to claim 6, characterized in that, Step S2 specifically includes: S21. Apply the first waterproof and breathable coating on the surface of the old decorative layer to form the first coating; S22. Insert porous breathable columns on the first coating. The porous breathable columns correspond to the splicing gaps of the old decorative layer. Multiple breathable channels for water vapor to pass through are provided inside the porous breathable columns. The inner ports of the breathable channels face the old decorative layer, and the outer ports can intercept water droplets. A temporary protective piece is provided at the outer end of the porous breathable column, and the temporary protective piece closes the outer ports of the breathable channels; S23. Wait for the first coating to dry, and then apply the second waterproof and breathable coating on the first coating to form the second coating; S24. Remove the temporary protective piece.

9. The construction method of the waterproof and breathable coating according to claim 6, characterized in that: When the porous breathable column is made of a hydrophilic material, both the inner end and the outer end of the porous breathable column are hydrophobic ends treated by hydrophobic treatment.

10. The construction method of the waterproof and breathable coating according to claim 1, characterized in that: The porous breathable column is a ceramic column or a plastic column, the diameter of the porous breathable column is 1-5 mm, and the pore diameter of the breathable channel is 5-30 μm; The inner end and the outer end of the porous breathable column are treated by hydrophobic treatment by dip-coating with solvent-free silane, and the dip-coating depth of the solvent-free silane is 0.5-1.5 mm.

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