A water-based coating and its preparation method and application

Abstract

The present invention discloses a water-based coating and a preparation method and application thereof, comprising the following raw materials in parts by weight: 45 to 55 parts of an organic-inorganic composite resin, 10 to 16 parts of lithium silicate, 5 to 9 parts of styrene-acrylic emulsion, 8 to 10 parts of a coupling agent, 8 to 15 parts of deionized water, 20 to 35 parts of a filler, 0.1 to 0.3 parts of a defoaming agent, and 0.2 to 0.5 parts of a leveling agent. The present invention adopts an organic-inorganic composite resin as the main film-forming resin, and reasonably optimizes the raw materials and content of the water-based coating. The prepared water-based coating has high waterproof performance and low water absorption. At the same time, the coating provided is a single-component water-based coating, which has the characteristics of simple construction and green and non-toxic.

Description

Technical Field

[0001] The invention belongs to the technical field of building waterproof coatings, and specifically relates to a water-based coating and a preparation method and application thereof. Background Art

[0002] The bathroom is an area with high water usage, which places high demands on waterproof materials. In order not to affect the residents downstairs and prevent water seepage in the bathroom, the bathroom's waterproof coating needs to have high impermeability and remain dry after water use in the bathroom area. At the same time, the bathroom waterproof material needs to have low water absorption.

[0003] At present, the commonly used bathroom waterproof coatings include polyurethane waterproof coatings, cement mortar waterproof coatings, acrylic waterproof coatings and polymer high molecular waterproof coatings. Polyurethane waterproof coatings are made of polyurethane and coal tar as raw materials. This waterproof coating has good anti-seepage performance, but the tar volatile during curing has a strong odor and is toxic to a certain extent; cement mortar waterproof coating is an adhesive, similar to special glue, which is prepared by mixing fine cement and sand and other aggregates, and then applied to the bathroom wall or floor. This waterproof coating has good environmental performance, excellent bonding and mechanical properties, However, its anti-penetration performance is poor; acrylic waterproof coating is based on self-cross-linking pure acrylic emulsion, which is dispersed and ground with special modifiers, functional additives and fillers. This type of material is non-toxic, harmless and has good construction performance, but the paint film of this type of material after curing is easy to absorb water and swell, and has a poor service life; polymer high molecular waterproof coatings are mostly made of rubber multi-chain high molecular materials, which have good ductility and elasticity, are colorless and odorless, and have good environmental protection performance, but this type of material has great viscosity before it is fully cured, and any slight bump or contact will cause damage to the waterproof film, resulting in poor construction performance. In the prior art, there are also permeable crystalline materials used as waterproof materials for bathrooms. For example, patent CN112831205A discloses a bathroom waterproof coating and its preparation method and application. The waterproof coating includes component A and component B; it has a good waterproof effect, can compact concrete and mortar, and improve its anti-seepage performance. At the same time, it is a water-based environmentally friendly coating. However, the waterproof coating is a two-component coating. During construction, component A needs to be sprayed 2 to 3 times. Each spraying needs to be interrupted for a period of time, and then component B is sprayed 2 to 3 times. The construction operation is complicated and cumbersome, and the construction period is long. Summary of the invention

[0004] The object of the present invention is to provide a water-based coating to solve at least one aspect of the problems and defects raised in the above-mentioned background technology.

[0005] The invention also provides a method for preparing the water-based coating.

[0006] The invention also provides application of the water-based paint.

[0007] According to one aspect of the present invention, a water-based coating is provided, comprising the following raw materials in parts by weight: 40 to 55 parts of an organic-inorganic composite resin, 8 to 15 parts of lithium silicate, 5 to 9 parts of a styrene-acrylic emulsion, 3 to 10 parts of a coupling agent, 8 to 15 parts of water, 20 to 35 parts of a filler, 0.1 to 0.3 parts of a defoaming agent, and 0.2 to 0.5 parts of a leveling agent;

[0008] The organic-inorganic composite resin is composed of the following raw materials by weight: 50 to 65 parts of waterborne polyurethane resin, 15 to 24 parts of methyltriethoxysilane, and 15 to 24 parts of silica sol.

[0009] According to a technical solution of a water-based coating technical solution of the present invention, at least the following

[0010] Beneficial effects:

[0011] The present invention adopts an organic-inorganic composite resin as a main film-forming material, which has excellent water-impermeability and low water absorption rate. The water-based polyurethane resin in the composite resin can generate a continuous and dense paint film after the paint is cured. At the same time, methyltriethoxysilane reacts with silica sol to generate modified silica sol, and the modified silica sol is hydrolyzed to generate silanol. The silanol has high activity and can be further cross-linked with active groups inside or on the surface of the water-based polyurethane resin, thereby enhancing the density of the surface layer of the coating film, thereby improving the water resistance of the water-based paint after curing.

[0012] In the present invention, lithium silicate can also be used as a film-forming substance. After solidification, it can form a coating film with a Si-O-Si structure, which has anti-fouling and water-resistant effects. At the same time, when solidifying into a film, the hydrolyzate of lithium silicate can react with Ca in the building base material (concrete or mortar, etc.). 2+ The ions generate CaSiO3 crystals, which can fill the pores on the building substrate (concrete or mortar, etc.), thus achieving a waterproof effect.

[0013] The styrene acrylic emulsion in the present invention can improve the dispersibility of lithium silicate in the organic-inorganic composite resin, making the resin film-forming material more uniform.

[0014] The coupling agent in the present invention plays a coupling role between the coating film and the building substrate, and also plays a coupling role between the main film-forming substance and the filler, so that the organic and inorganic substances in the coating can be effectively combined. When the coating is cured, each component in the coating exerts its maximum performance, thereby achieving the characteristics of impermeability and low water absorption.

[0015] The defoaming agent in the present invention can effectively eliminate bubbles generated during the preparation process of the coating, avoid the generation of bubbles and affect the density of the coating, and then affect the waterproof performance; the leveling agent can make the coating evenly level on the coated substrate to form a dense coating film; the filler can reduce the cost and fill the large gaps in the coated substrate to achieve a waterproof effect; water is used as a solvent to adjust the viscosity of the coating, and it is environmentally friendly and non-toxic.

[0016] In the present invention, by controlling the weight of the raw materials, the raw materials can be reasonably matched to achieve the characteristics of waterproofness and low water permeability.

[0017] In some specific embodiments of the present invention, the filler is at least one of quartz, calcium carbonate, titanium dioxide or barium sulfate.

[0018] In some specific embodiments of the present invention, the coupling agent is at least one of KH560, KH550 and KH570.

[0019] In some specific embodiments of the present invention, the defoaming agent is a water-based silicone defoaming agent.

[0020] In some specific embodiments of the present invention, the leveling agent is a water-based silicone leveling agent.

[0021] In some specific embodiments of the present invention, the grade of the waterborne polyurethane resin is AH-1720A.

[0022] In some specific embodiments of the present invention, the silica sol is NS12-30 / 1.

[0023] In some specific embodiments of the present invention, the brand of the methyltriethoxysilane is GX-173.

[0024] In some specific embodiments of the present invention, the brand of the styrene acrylic emulsion is SH7199A.

[0025] A second aspect of the present invention provides a method for preparing a water-based coating, comprising the following steps:

[0026] S1, adding the mixed solution of methyltriethoxysilane and ethanol dropwise into the silica sol aqueous solution for reaction to obtain modified silica sol;

[0027] S2. Mix the modified silica sol and waterborne polyurethane resin and stir them evenly to obtain an organic-inorganic composite resin, then add water, lithium silicate, styrene acrylic emulsion, coupling agent, filler, defoamer and leveling agent in sequence, mix them evenly, and obtain a waterborne coating.

[0028] According to a technical solution of a method for preparing a water-based coating of the present invention, at least the following beneficial effects are achieved:

[0029] The present invention firstly modifies silica sol with methyltriethoxysilane, and utilizes the hydroxyl groups generated by the hydrolysis of methyltriethoxysilane to react with the hydroxyl groups on the surface of the silica sol, so as to introduce highly hydrophobic alkyl groups into the surface of the silica sol, and hydrophobically modify the silica sol. Then, the modified silica sol is blended with an aqueous polyurethane resin to obtain an organic-inorganic composite resin. When the resin is cured, the silica sol in the resin is hydrolyzed, and the solvent is volatilized, so as to obtain a hydrophobic and dense coating film, and the coating film has the characteristics of being waterproof and water-resistant after curing.

[0030] In some specific embodiments of the present invention, the mass ratio of silica sol to water in the silica sol aqueous solution is 3 to 5:1.

[0031] In some specific embodiments of the present invention, the mass ratio of methyltriethoxysilane to ethanol is 1:1-3.

[0032] In some specific embodiments of the present invention, the mass ratio of the modified silica sol to the aqueous polyurethane resin is 1:2-5.

[0033] In some specific embodiments of the present invention, the mass ratio of the modified silica sol to the aqueous polyurethane resin is 1:3-5.

[0034] The present invention realizes the stable combination of organic and inorganic resins by controlling the mass ratio of modified silica sol and waterborne polyurethane resin, thereby achieving excellent waterproof effect.

[0035] In some specific embodiments of the present invention, the dropping time is 20 min to 40 min.

[0036] In some specific embodiments of the present invention, the dropping time is 22 min to 39 min.

[0037] In some specific embodiments of the present invention, the dropping time is 25 min to 37 min.

[0038] The present invention can prepare a stable and hydrophobic modified silica sol by controlling the dropping speed. If the dropping time is too short, the hydrophobic group cannot be introduced into the silica sol in time, resulting in self-crosslinking of the methyltriethoxysilane after hydrolysis, and the effect of enhancing the hydrophobicity cannot be achieved. If the dropping time is too long, the silica sol is easily self-polymerized, and the hydrophobic effect cannot be effectively achieved.

[0039] In some specific embodiments of the present invention, the reaction temperature is 40°C to 60°C.

[0040] In some specific embodiments of the present invention, the reaction temperature is 45°C to 60°C.

[0041] The present invention achieves the effect of enhancing the hydrophobicity of silica sol by controlling the reaction temperature of methyltriethoxysilane and silica sol. If the reaction temperature is too low, the hydrolysis of silica sol and methyltriethoxysilane is affected, affecting the efficiency. If the reaction temperature is too high, the self-condensation reaction of silica sol is likely to occur.

[0042] In some specific embodiments of the present invention, the reaction time is 2 h to 4 h.

[0043] In some specific embodiments of the present invention, the reaction time is 2 h to 3.5 h.

[0044] The present invention simultaneously controls the reaction time of methyltriethoxysilane and silica sol to achieve the effect of enhancing the hydrophobicity of silica sol. If the reaction time is too short, methyltriethoxysilane cannot modify the silica sol in time, thereby failing to achieve the effect of enhancing the hydrophobicity. If the reaction time is too long, the production efficiency is affected and the cost is increased.

[0045] A third aspect of the present invention provides an application of a water-based coating in preparing a building waterproof layer.

[0046] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0047] 1. The present invention firstly performs hydrophobic modification on silica sol to obtain modified silica sol, which is then mixed with waterborne polyurethane to obtain an organic-inorganic composite resin having the properties of both organic and inorganic resins and excellent waterproof performance. At the same time, lithium silicate and silane coupling agent are used to make the coating film after curing have low water absorption performance.

[0048] 2. The present invention uses water as a solvent, which is green, environmentally friendly, non-toxic and low-cost. At the same time, the water-based paint provided by the present invention is a single-component paint, which is easy to construct and avoids inaccurate paint mixing that affects the paint performance. DETAILED DESCRIPTION

[0049] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0050] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0051] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0052] Specific embodiments of the present invention are described in detail below.

[0053] The waterborne polyurethane resin in this embodiment or comparative example was purchased from Anda Huatai New Material Technology Co., Ltd.

[0054] The silica sol in this embodiment or comparative example was purchased from Zhejiang Delixin Micro-Nano Technology Co., Ltd.

[0055] In this embodiment or comparative example, methylethoxysilane was purchased from Anhui Sibao Organic Silicon New Materials Co., Ltd.

[0056] The styrene acrylic emulsion in this embodiment or comparative example was purchased from Shandong Changyao New Materials Co., Ltd.

[0057] The modulus of lithium silicate in this embodiment or comparative example is 4.0.

[0058] The water-based organosilicon defoamer in this embodiment or comparative example is DF-853, which is purchased from Zhanjiang Defeng Defoamer Co., Ltd.

[0059] The water-based organosilicon leveling agent in this embodiment or comparative example is ZY-1104, which is purchased from Shanghai Ziyi Chemical Co., Ltd.

[0060] In this embodiment or comparative example, the coupling agent is KH560.

[0061] Example 1

[0062] This embodiment is a water-based coating, which is composed of the following raw materials in parts by weight: 45 parts of organic-inorganic composite resin, 12 parts of lithium silicate, 5 parts of styrene-acrylic emulsion, 6 parts of coupling agent, 10 parts of water, 22 parts of calcium carbonate, 0.1 parts of water-based organosilicon defoaming agent, and 0.3 parts of water-based organosilicon leveling agent.

[0063] The organic-inorganic composite resin in this embodiment includes the following raw materials in parts by weight: 60 parts of waterborne polyurethane resin, 20 parts of methyltriethoxysilane, and 15 parts of silica sol.

[0064] The preparation method of the water-based coating in this embodiment consists of the following steps:

[0065] S1, mixing silica sol with water to obtain a silica sol aqueous solution, the mass ratio of silica sol to water is 4:1, and then methyltriethoxysilane and ethanol are mixed in a mass ratio of 1:2 and then dropwise added to the silica sol aqueous solution, the dropping time is controlled to be 30min, and then reacting for 2.5h, and the reaction temperature is controlled to be 55°C to obtain a modified silica sol;

[0066] S2. Mix the modified silica sol with the waterborne polyurethane resin, control the stirring speed to 500r / min, stir evenly to obtain an organic-inorganic composite resin, then add lithium silicate and styrene-acrylic emulsion and mix evenly, finally add water, KH560, calcium carbonate, waterborne organosilicon defoamer and waterborne organosilicon leveling agent in sequence, mix evenly again, and obtain a waterborne coating.

[0067] Example 2

[0068] This embodiment is a water-based coating, which is composed of the following raw materials in parts by weight: 40 parts of organic-inorganic composite resin, 10 parts of lithium silicate, 5 parts of styrene-acrylic emulsion, 6 parts of coupling agent, 12 parts of water, 27 parts of calcium carbonate, 0.1 parts of water-based organosilicon defoaming agent, and 0.3 parts of water-based organosilicon leveling agent.

[0069] The organic-inorganic composite resin in this embodiment includes the following raw materials in parts by weight: 60 parts of waterborne polyurethane resin, 20 parts of methyltriethoxysilane, and 15 parts of silica sol.

[0070] The preparation method of the water-based coating in this embodiment consists of the following steps:

[0071] S1, mixing silica sol with water to obtain a silica sol aqueous solution, the mass ratio of silica sol to water is 4:1, and then methyltriethoxysilane and ethanol are mixed in a mass ratio of 1:2 and then dropwise added to the silica sol aqueous solution, the dropping time is controlled to be 30min, and then reacting for 2.5h, and the reaction temperature is controlled to be 55°C to obtain a modified silica sol;

[0072] S2. Mix the modified silica sol with the waterborne polyurethane resin, control the stirring speed to 500r / min, stir evenly to obtain an organic-inorganic composite resin, then add lithium silicate and styrene-acrylic emulsion and mix evenly, finally add water, KH560, calcium carbonate, waterborne organosilicon defoamer and waterborne organosilicon leveling agent in sequence, mix evenly again, and obtain a waterborne coating.

[0073] Example 3

[0074] This embodiment is a water-based coating, which is composed of the following raw materials in parts by weight: 45 parts of organic-inorganic composite resin, 12 parts of lithium silicate, 5 parts of styrene-acrylic emulsion, 6 parts of coupling agent, 10 parts of water, 22 parts of calcium carbonate, 0.1 parts of water-based organosilicon defoaming agent, and 0.3 parts of water-based organosilicon leveling agent.

[0075] The organic-inorganic composite resin in this embodiment includes the following raw materials in parts by weight: 60 parts of waterborne polyurethane resin, 15 parts of methyltriethoxysilane, and 21 parts of silica sol.

[0076] The preparation method of the water-based coating in this embodiment consists of the following steps:

[0077] S1, mixing silica sol with water to obtain a silica sol aqueous solution, the mass ratio of silica sol to water is 4:1, and then methyltriethoxysilane and ethanol are mixed in a mass ratio of 1:2 and then dropwise added to the silica sol aqueous solution, the dropping time is controlled to be 30min, and then reacting for 2.5h, and the reaction temperature is controlled to be 55°C to obtain a modified silica sol;

[0078] S2. Mix the modified silica sol with the waterborne polyurethane resin, control the stirring speed to 500r / min, stir evenly to obtain an organic-inorganic composite resin, then add lithium silicate and styrene-acrylic emulsion and mix evenly, finally add water, KH560, calcium carbonate, waterborne organosilicon defoamer and waterborne organosilicon leveling agent in sequence, mix evenly again, and obtain a waterborne coating.

[0079] Comparative Example 1

[0080] This comparative example is a water-based coating, which is composed of the following raw materials in parts by weight: 45 parts of water-based polyurethane resin, 12 parts of lithium silicate, 5 parts of styrene-acrylic emulsion, 6 parts of coupling agent, 10 parts of water, 22 parts of calcium carbonate, 0.1 parts of water-based organosilicon defoaming agent, and 0.3 parts of water-based organosilicon leveling agent.

[0081] The preparation method of the water-based coating in this embodiment consists of the following steps:

[0082] Mix water-based polyurethane resin with water, then add lithium silicate and styrene acrylic emulsion and mix evenly, finally add KH560, calcium carbonate, water-based organosilicon defoamer and water-based organosilicon leveling agent in sequence, mix evenly again, and obtain water-based coating.

[0083] Comparative Example 2

[0084] This embodiment is a water-based coating, which is composed of the following raw materials in parts by weight: 45 parts of organic-inorganic composite resin, 12 parts of lithium silicate, 5 parts of styrene-acrylic emulsion, 6 parts of coupling agent, 10 parts of water, 27 parts of calcium carbonate, 0.1 parts of water-based organosilicon defoaming agent, and 0.3 parts of water-based organosilicon leveling agent.

[0085] The organic-inorganic composite resin in this embodiment includes the following raw materials in parts by weight: 60 parts of waterborne polyurethane resin, 5 parts of methyltriethoxysilane, and 15 parts of silica sol.

[0086] The preparation method of the water-based coating in this embodiment consists of the following steps:

[0087] S1, mixing silica sol with water to obtain a silica sol aqueous solution, the mass ratio of silica sol to water is 4:1, and then methyltriethoxysilane and ethanol are mixed in a mass ratio of 1:2 and then dropwise added to the silica sol aqueous solution, the dropping time is controlled to be 10 minutes, and then reacting for 2.5 hours, and the reaction temperature is controlled to be 55°C to obtain a modified silica sol;

[0088] S2. Mix the modified silica sol with the waterborne polyurethane resin, control the stirring speed to 500r / min, stir evenly to obtain an organic-inorganic composite resin, then add lithium silicate and styrene-acrylic emulsion and mix evenly, finally add water, KH560, calcium carbonate, waterborne organosilicon defoamer and waterborne organosilicon leveling agent in sequence, mix evenly again, and obtain a waterborne coating.

[0089] The examples 1 to 3 and comparative examples 1 to 2 were tested for water-impermeability and water absorption. The water-impermeability test specifically referred to GB / T23445-2009 polymer cement waterproof coating, and the test pressure was 0.3 MPa. The longer the pressurization time, the better the water-impermeability. The water absorption test referred to GB / T19250-2013 polyurethane waterproof coating. The test results are shown in Table 1.

[0090] Table 1 Test results of water-impermeability and water absorption of water-based coatings of Examples 1 to 3 and Comparative Examples 1 to 2

[0091] - Pressurized watertight time / min Water absorption / % Example 1 125min 0.5 Example 2 116min 0.8 Example 3 120min 1.2 Comparative Example 1 57min 6.0 Comparative Example 2 65min 6.4

[0092] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 uses waterborne polyurethane resin as the main film-forming material, and the waterborne polyurethane resin is not modified by inorganic compounding. As can be seen from Table 1, the water-impermeable performance and water absorption rate of the water-borne coating prepared in Comparative Example 1 are worse than those of the water-borne coating prepared in Example 1. This is mainly because the modified silica sol in Example 1 can be hydrolyzed to generate silanols, which have high activity and can be further cross-linked with active groups inside or on the surface of the waterborne polyurethane resin, which greatly improves the density of the surface layer of the paint film, thereby improving the water-impermeable performance and reducing the water absorption rate.

[0093] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 reduces the content of methyltriethoxysilane and shortens the dropping time. It can be seen from Table 1 that the pressurized water-proof time of the water-based coating obtained in Comparative Example 2 is 65min, and the water absorption rate is 6.4%. This is mainly because after reducing the content of methyltriethoxysilane, the content of hydrophobic groups is reduced, and the dropping time is shortened, so that methyltriethoxysilane fails to modify the silica sol in time, and the introduced hydrophobic groups are reduced, resulting in poor hydrophobicity of the paint film, which in turn causes the water absorption rate of the paint film to increase.

[0094] In summary, the present invention firstly performs hydrophobic modification on silica sol to obtain modified silica sol, and then mixes and compounds it with waterborne polyurethane to obtain an organic-inorganic composite resin, which has the characteristics of both organic and inorganic resins and has excellent waterproof performance. At the same time, lithium silicate and silane coupling agent are used to make the coating film after curing have low water absorption performance; the present invention uses deionized water as a solvent, which is green, environmentally friendly, non-toxic and low-cost. At the same time, the water-based paint provided by the present invention is a single-component paint, which is easy to construct and avoids inaccurate paint mixing that affects the paint performance.

[0095] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A water-based paint, characterized in that: The preparation material comprises the following parts by weight: 40 to 55 parts of organic-inorganic composite resin, 8 to 15 parts of lithium silicate, 5 to 9 parts of styrene-acrylic emulsion, 3 to 10 parts of coupling agent, 8 to 15 parts of water, 20 to 35 parts of filler, 0.1 to 0.3 parts of defoaming agent, and 0.2 to 0.5 parts of leveling agent; The organic-inorganic composite resin comprises the following raw materials in parts by weight: 50 to 65 parts of waterborne polyurethane resin, 15 to 24 parts of methyltriethoxysilane, and 15 to 24 parts of silica sol; it also comprises water and ethanol; the mass ratio of the silica sol to water is 3 to 5:1, and the mass ratio of the methyltriethoxysilane to ethanol is 1:1 to 3; The method for preparing a water-based coating comprises the following steps: S1, mixing silica sol with water to obtain a silica sol aqueous solution, and then dropping the methyltriethoxysilane and ethanol mixed solution into the silica sol aqueous solution for reaction to obtain a modified silica sol; S2, mixing the modified silica sol and waterborne polyurethane resin to obtain an organic-inorganic composite resin, and then sequentially adding the water, lithium silicate, styrene acrylic emulsion, coupling agent, filler, defoamer and leveling agent, mixing evenly to obtain a waterborne coating.

2. A water-based paint according to claim 1, characterized in that: The filler is at least one of quartz, calcium carbonate, titanium dioxide or barium sulfate.

3. A water-based paint according to claim 1, characterized in that: The coupling agent is at least one of KH560, KH550 and KH570.

4. A water-based paint according to claim 1, characterized in that: The defoamer is a water-based organosilicon defoamer.

5. A water-based paint according to claim 1, characterized in that: The leveling agent is a water-based organic silicon leveling agent.

6. A water-based paint according to claim 1, characterized in that: The dropping time is 20min~40min.

7. A water-based paint according to claim 1, characterized in that: The reaction temperature is 40°C to 60°C.

8. A water-based paint according to claim 1, characterized in that: The reaction time is 2h~4h.

9. Use of a water-based coating as claimed in any one of claims 1 to 5 in preparing a building waterproof layer.