An anti-flooding polymer cement waterproof coating suitable for low-temperature and high-humidity environment

Abstract

The waterproof emulsion suitable for the polymer cement waterproof coating in a low-temperature and high-humidity environment is prepared by a free radical emulsion polymerization reaction, with a vinyl monomer, 2-acrylamide-2-methyl propane sulfonic acid and the like as a comonomer, through anion / emulsion emulsifier and mechanical stirring, dropwise adding an initiator, and with functional additives and preservatives, to obtain a benzene and propylene emulsion containing carboxylic acid group, sulfonic acid group and phosphoric acid group. The polymer cement waterproof coating prepared by using the benzene and propylene emulsion has good mechanical properties, good chelation, low limit inhibition and lattice distortion, can easily be adsorbed on the tiny calcium carbonate crystal grains in a low-temperature and high-humidity environment, and the like, prevents the formation and precipitation of calcium carbonate, and has strong anti-efflorescence ability.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to an anti-alkali efflorescence polymer cement waterproof coating suitable for low temperature and high humidity environments. Technical Background

[0002] Polymer cement waterproof coating, or JS waterproof coating for short, is a two-component, water-based building waterproof coating made by combining an organic liquid component (composed of polymer emulsion and various additives) with an inorganic powder component (composed of cement, quartz sand, calcium carbonate, and other inorganic fillers and additives) through a reasonable ratio. Due to its comprehensive advantages such as flexibility, high adhesion strength to damp substrates, convenient construction, excellent overall waterproofing effect, and environmental friendliness, it is currently a widely used waterproof product on the market and has become an indispensable material in the field of building waterproofing materials. However, because the main gelling material of polymer cement waterproof coating is silicate cement, the main minerals in silicate cement react with water to generate hydroxide ions, which combine with metal ions to form hydroxides with low solubility. During the drying and curing process of the coating, as moisture evaporates and migrates, the internal hydroxides react with carbon dioxide in the air on the coating surface to form white crystalline calcium carbonate with extremely low solubility. Over time, this accumulates on the surface, forming crystals and causing a whitening and mottled appearance, known as "alkali efflorescence." Especially in low-temperature and high-humidity environments, moisture evaporating from the coating and condensing in the air cannot evaporate and dissipate in time, making it easier for it to accumulate on the coating surface, forming efflorescence and affecting the coating's appearance. The occurrence of these phenomena has, to some extent, restricted the application and promotion of polymer cement waterproof coatings, especially in low-temperature and high-humidity environments. Currently, there is no good solution to this problem; therefore, developing an efflorescence-resistant polymer cement waterproof coating suitable for low-temperature and high-humidity environments is of significant practical importance. Summary of the Invention

[0003] The purpose of this invention is to solve the common problems described in the background section and to provide an anti-alkali efflorescence polymer cement waterproof coating suitable for low temperature and high humidity environments.

[0004] The process of efflorescence and whitening in cement-based coatings is that excess water or ambient humidity in the system enters and exits through the capillaries inside the coating, carrying the alkali (mainly calcium hydroxide) to the surface of the substrate. The alkali reacts with moisture and carbon dioxide in the air to produce calcium carbonate, a white substance that is insoluble in water. This is the process of efflorescence.

[0005] Based on the causes of efflorescence, the main approaches to suppressing efflorescence include: adjusting the type and amount of cement added to slow down the hydration reaction of cement and reduce the precipitation of calcium carbonate; improving the sealing function of the coating film to reduce migration and precipitation channels and prevent internal alkali from migrating to the surface.

[0006] This invention is achieved through the following technical means: First, a phosphate emulsifier is used to prepare the styrene-acrylic emulsion, and anionic groups such as phosphate groups are introduced through functional monomers. These anions have good chelating properties, low-limit inhibition, and lattice distortion, and are easily adsorbed onto tiny calcium carbonate crystals. Furthermore, these anions readily replace carbonate ions, thus preventing the precipitation of calcium carbonate. Second, metaphosphate ions in the post-addition can form coordinate bonds with calcium ions, thereby forming stable chelate particles. Especially under low temperature and high humidity environments, these particles cannot be carried to the coating surface for crystallization with the migration of moisture, thus preventing the precipitation of calcium carbonate and other substances. The resulting styrene-acrylic emulsion has a strong resistance to efflorescence. Third, the raw material components in the powder of the polymer cement waterproof coating are rationally formulated, especially with strict control over the amount of silicate cement added. The selected 70-140 mesh quartz sand has a reasonable particle size distribution between coarse and fine particles, resulting in a dense coating film. This reduces the migration channels of the coating film, further reducing the precipitation of calcium carbonate and other substances, and inhibiting efflorescence. Based on the above characteristics, improvements were made to both the liquid and powder components, resulting in a polymer cement waterproof coating that possesses both excellent mechanical properties and strong resistance to efflorescence and adaptability to various construction methods.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] An alkali-resistant polymer cement waterproof coating suitable for low-temperature and high-humidity environments, comprising a liquid component and a powder component:

[0009] The liquid component, by weight, comprises: 92-96 parts of styrene-acrylic emulsion, 0.05-0.2 parts of dispersant, 0.1-0.3 parts of defoamer, 0.2-0.4 parts of preservative, 0.1-0.3 parts of hydrophobic modified alkali-swelling thickener, and 4-8 parts of water;

[0010] By weight, the powder comprises: 30-40 parts of 42.5 ordinary Portland cement, 40-50 parts of 70-140 mesh quartz sand, and 10-30 parts of 200 mesh heavy calcium carbonate.

[0011] The liquid and powder should be mixed and stirred evenly at a mass ratio of 1:1.4~1.6 before use.

[0012] Preferably, the fineness requirement of the 70-140 mesh quartz sand is that the residue on the sieve after screening with superimposed 70 mesh and 140 mesh sieves is ≤10% for 70 mesh and ≥75% for 140 mesh. The fineness of the sand has a certain impact on efflorescence.

[0013] Preferably, the preparation method of the styrene-acrylic emulsion is as follows, by weight percentage:

[0014] 1) First, add 6-12 parts of phosphoric acid emulsifier, 9-18 parts of anionic / anionic emulsifier composed of sodium dodecyl sulfonate, and 300-360 parts of water to the reactor and stir evenly. While stirring, slowly add one-third of the mixture composed of 60-100 parts of methyl methacrylate or styrene, 320-400 parts of n-butyl acrylate and 44-52 parts of crosslinking monomer maleic anhydride, trimethylamine ethyl methacrylate or hydroxypropyl acrylate. While stirring, raise the temperature and pre-disperse at 50°C for 30 minutes to obtain a milky white pre-emulsion.

[0015] 2) Adjust the pH value to 7-8 with a pH adjuster, raise the temperature to 80℃, and then add one-third of an aqueous solution of a water-soluble initiator consisting of 3-6 parts of persulfate and 30-50 parts of water. After nucleation for 20 minutes, a blue seed emulsion is obtained.

[0016] 3) Slowly add the remaining two-thirds of the mixed monomers from step 1), the remaining two-thirds of the water-soluble initiator aqueous solution from step 2), and the remaining 30-50 parts of the functional monomers simultaneously. After the addition is completed in 2-3 hours, continue the reaction for about 2-3 hours. Adjust the pH of the system to 7.5±0.1 with a pH adjuster. Then add 8-12 parts of preservative, 2-4 parts of additive, and 15-25 parts of water in sequence. Filter to obtain a styrene-acrylic emulsion for polymer cement waterproof coatings with anti-efflorescence properties.

[0017] Preferably, the emulsification system used to prepare the styrene-acrylic emulsion includes a phosphate-containing emulsifier. The added phosphate groups and other anionic groups have good chelating properties, low-limit inhibition, and lattice distortion. Under low temperature and high humidity conditions, they are easily adsorbed onto tiny calcium carbonate crystals. At the same time, the metaphosphate ions in the functional additives are easy to chelate with calcium ions to form large particles, which cannot be carried to the coating surface for crystallization with the migration of water, thereby preventing the precipitation of calcium carbonate and other substances, and giving the coating a strong resistance to alkali efflorescence.

[0018] Preferably, the phosphate-containing emulsifier is one of alkylphenol polyoxyethylene ether phosphate or sodium isooctanol polyoxyethylene ether phosphate.

[0019] Preferably, the functional monomer is 2-acrylamide-2-methylpropanesulfonic acid.

[0020] Preferably, the post-additive is sodium hexametaphosphate or an aqueous solution of sodium hexametaphosphate.

[0021] The technical solution of this invention improves both the liquid and powder components. The styrene-acrylic emulsion used to prepare the liquid component is endowed with excellent chelating properties, low-limit inhibition, and lattice distortion through comprehensive means, thereby preventing the precipitation of calcium carbonate. Combined with the reasonable composition of each raw material in the powder component, especially the strict control of the amount of silicate cement added, and the selection of 70-140 mesh quartz sand with a reasonable particle size distribution between coarse and fine particles, the resulting coating film is dense, reducing the migration channels of the coating film, thereby further reducing the precipitation of calcium carbonate and other substances. As a result, the polymer cement waterproof coating has both good mechanical properties and strong resistance to efflorescence and adaptability to construction. Attached Figure Description

[0022] Figure 1 For comparison of the implementation effects of the examples and comparative examples Detailed Implementation

[0023] The following examples are used to illustrate the present invention, so that those skilled in the art can refer to the specification to reproduce the experimental results, but are not intended to limit the scope of the present invention.

[0024] In the following examples and comparative examples, the dispersant used was Nopco 5040; the defoamer was BASF MO2157; the isothiazolinone preservative was Hanning 616; the hydrophobic modified alkali-swelling thickener was AkzoNobel L344; and the cement was Jidong PO 42.5 silicate cement.

[0025] Example 1:

[0026] Anti-alkali efflorescence polymer cement waterproof coatings suitable for low temperature and high humidity environments include liquid and powder formulations:

[0027] By weight, the liquid component includes: 92 parts styrene-acrylic emulsion, 0.2 parts dispersant, 0.1 parts defoamer, 0.2 parts preservative, 0.3 parts hydrophobically modified alkali-swelling thickener, and 8 parts water;

[0028] By weight, the powder includes: 40 parts of 42.5 ordinary Portland cement, 40 parts of 70~140 mesh quartz sand, and 20 parts of 200 mesh heavy calcium carbonate.

[0029] The liquid and powder should be mixed and stirred evenly at a mass ratio of 1:1.4 before use.

[0030] The preparation steps of the styrene-acrylic emulsion are as follows: First, add 12 parts of anionic / anionic emulsifier composed of alkylphenol polyoxyethylene ether phosphate and 9 parts of sodium dodecyl sulfonate, and 300 parts of water to a reactor and stir until homogeneous. While stirring, slowly add one-third of a mixture composed of 50 parts methyl methacrylate, 50 parts styrene, 320 parts n-butyl acrylate, 22 parts maleic anhydride, and 22 parts trimethylamine ethyl methacrylate. While stirring, raise the temperature and pre-disperse at 50°C for 30 minutes to obtain a milky white pre-emulsion. 2) Adjust the pH value to 7-8 with a pH adjuster, raise the temperature to 80°C, and then... Add one-third of the aqueous solution of a water-soluble initiator consisting of 3 parts persulfate and 30 parts water. After nucleation in 20 minutes, a blue seed emulsion is obtained. 3) Add the remaining two-thirds of the mixed monomers from step 1), the remaining two-thirds of the aqueous solution of the water-soluble initiator from step 2), and the remaining 30 parts of 2-acrylamide-2-methylpropanesulfonic acid dropwise simultaneously and slowly. After the addition is completed in 2-3 hours, continue the reaction for about 2-3 hours. Adjust the pH of the system to 7.5±0.1 with a pH adjuster. Add 8 parts of preservative, 2 parts of sodium hexametaphosphate, and 25 parts of water in sequence. Filter to obtain the final product.

[0031] Example 2:

[0032] Anti-alkali efflorescence polymer cement waterproof coatings suitable for low temperature and high humidity environments include liquid and powder formulations:

[0033] By weight, the liquid component includes: 93 parts styrene-acrylic emulsion, 0.15 parts dispersant, 0.15 parts defoamer, 0.25 parts preservative, 0.25 parts hydrophobically modified alkali-swelling thickener, and 7 parts water;

[0034] By weight, the powder includes: 35 parts of 42.5 ordinary Portland cement, 45 parts of 70~140 mesh quartz sand, and 20 parts of 200 mesh heavy calcium carbonate.

[0035] The liquid and powder should be mixed and stirred evenly at a mass ratio of 1:1.6 before use.

[0036] The preparation steps of the styrene-acrylic emulsion are as follows: First, add 12 parts of anionic / anionic emulsifier composed of sodium isooctanol polyoxyethylene ether phosphate and 11 parts of sodium dodecyl sulfonate, and 320 parts of water to a reactor and stir until homogeneous. While stirring, slowly add one-third of a mixture composed of 45 parts methyl methacrylate, 45 parts styrene, 340 parts n-butyl acrylate, 23 parts maleic anhydride, and 23 parts hydroxypropyl acrylate. While stirring, raise the temperature and pre-disperse at 50°C for 30 minutes to obtain a milky white pre-emulsion. 2) Adjust the pH value to 7-8 with a pH adjuster, raise the temperature to 80°C, and then drop... Add one-third of a water-soluble initiator aqueous solution consisting of 4 parts persulfate and 35 parts water. After nucleation in 20 minutes, a blue seed emulsion is obtained. 3) Slowly add the remaining two-thirds of the mixed monomers from step 1), the remaining two-thirds of the water-soluble initiator aqueous solution from step 2), and the remaining 35 parts of 2-acrylamide-2-methylpropanesulfonic acid dropwise simultaneously. After the addition is completed in 2-3 hours, continue the reaction for about 2-3 hours. Adjust the pH of the system to 7.5±0.1 with a pH adjuster. Then add 9 parts of preservative, 3 parts of sodium hexapolyphosphate, and 25 parts of water aqueous solution in sequence. Filter to obtain the final product.

[0037] Example 3:

[0038] Anti-alkali efflorescence polymer cement waterproof coatings suitable for low temperature and high humidity environments include liquid and powder formulations:

[0039] By weight, the liquid component includes: 94 parts styrene-acrylic emulsion, 0.1 parts dispersant, 0.2 parts defoamer, 0.3 parts preservative, 0.2 parts hydrophobically modified alkali-swelling thickener, and 6 parts water;

[0040] By weight, the powder includes: 30 parts of 42.5 ordinary Portland cement, 50 parts of 70~140 mesh quartz sand, and 20 parts of 200 mesh heavy calcium carbonate.

[0041] The liquid and powder should be mixed and stirred evenly at a mass ratio of 1:1.5 before use.

[0042] The preparation steps of the styrene-acrylic emulsion are as follows: First, add 10 parts of alkylphenol polyoxyethylene ether phosphate, 13 parts of sodium dodecyl sulfonate (an anionic / anionic emulsifier), and 340 parts of water to a reactor and stir until homogeneous. While stirring, slowly add one-third of a mixture consisting of 40 parts methyl methacrylate, 40 parts styrene, 380 parts n-butyl acrylate, 24 parts trimethylamine ethyl acrylate, and 24 parts hydroxypropyl acrylate. While stirring, raise the temperature and pre-disperse at 50°C for 30 minutes to obtain a milky white pre-emulsion. 2) Adjust the pH value to 7-8 with a pH adjuster, raise the temperature to 80°C, and then... Then, add one-third of the aqueous solution of a water-soluble initiator consisting of 5 parts persulfate and 40 parts water. After nucleation in 20 minutes, a blue seed emulsion is obtained. 3) Add the remaining two-thirds of the mixed monomers from step 1), the remaining two-thirds of the aqueous solution of the water-soluble initiator from step 2), and the remaining 40 parts of 2-acrylamide-2-methylpropanesulfonic acid dropwise simultaneously and slowly. After the addition is completed in 2-3 hours, continue the reaction for about 2-3 hours. Adjust the pH of the system to 7.5±0.1 with a pH adjuster. Then, add 10 parts of preservative, 4 parts of sodium hexametaphosphate, and 20 parts of water in sequence. Filter to obtain the final product.

[0043] Example 4:

[0044] Anti-alkali efflorescence polymer cement waterproof coatings suitable for low temperature and high humidity environments include liquid and powder formulations:

[0045] By weight, the liquid component includes: 95 parts styrene-acrylic emulsion, 0.05 parts dispersant, 0.25 parts defoamer, 0.35 parts preservative, 0.15 parts hydrophobically modified alkali-swelling thickener, and 5 parts water;

[0046] By weight, the powder includes: 30 parts of 42.5 ordinary Portland cement, 40 parts of 70~140 mesh quartz sand, and 30 parts of 200 mesh heavy calcium carbonate.

[0047] The liquid and powder should be mixed and stirred evenly at a mass ratio of 1:1.4 before use.

[0048] The preparation steps of the styrene-acrylic emulsion are as follows: First, add 8 parts of anionic / anionic emulsifier composed of sodium isooctanol polyoxyethylene ether phosphate and 15 parts of sodium dodecyl sulfonate, and 350 parts of water to a reactor and stir until homogeneous. While stirring, slowly add one-third of a mixture composed of 35 parts methyl methacrylate, 35 parts styrene, 380 parts n-butyl acrylate, 25 parts trimethylamine ethyl acrylate, and 25 parts hydroxypropyl acrylate. While stirring, raise the temperature and pre-disperse at 50°C for 30 minutes to obtain a milky white pre-emulsion; 2) Adjust the pH value to 7-8 with a pH adjuster, raise the temperature to 80°C, and then... Then, add one-third of the aqueous solution of a water-soluble initiator consisting of 6 parts persulfate and 40 parts water. After nucleation in 20 minutes, a blue seed emulsion is obtained. 3) Add the remaining two-thirds of the mixed monomers from step 1), the remaining two-thirds of the aqueous solution of the water-soluble initiator from step 2), and the remaining 45 parts of 2-acrylamide-2-methylpropanesulfonic acid dropwise simultaneously and slowly. After the addition is completed in 2-3 hours, continue the reaction for about 2-3 hours. Adjust the pH of the system to 7.5±0.1 with a pH adjuster. Then, add 11 parts of preservative, 2 parts of sodium hexametaphosphate, and 20 parts of water in sequence. Filter to obtain the final product.

[0049] Example 5:

[0050] Anti-alkali efflorescence polymer cement waterproof coatings suitable for low temperature and high humidity environments include liquid and powder formulations:

[0051] By weight, the liquid component includes: 96 parts styrene-acrylic emulsion, 0.15 parts dispersant, 0.3 parts defoamer, 0.4 parts preservative, 0.1 parts hydrophobically modified alkali-swelling thickener, and 4 parts water;

[0052] By weight, the powder includes: 40 parts of 42.5 ordinary Portland cement, 50 parts of 70~140 mesh quartz sand, and 10 parts of 200 mesh heavy calcium carbonate.

[0053] The liquid and powder should be mixed and stirred evenly at a mass ratio of 1:1.6 before use.

[0054] The preparation steps of the styrene-acrylic emulsion are as follows: First, add 6 parts of alkylphenol polyoxyethylene ether phosphate, 18 parts of sodium dodecyl sulfonate (an anionic / anionic emulsifier), and 360 parts of water to a reactor and stir until homogeneous. While stirring, slowly add one-third of a mixture consisting of 30 parts methyl methacrylate, 30 parts styrene, 400 parts n-butyl acrylate, 26 parts trimethylamine ethyl acrylate, and 26 parts hydroxypropyl acrylate. While stirring, raise the temperature and pre-disperse at 50°C for 30 minutes to obtain a milky white pre-emulsion. 2) Adjust the pH value to 7-8 with a pH adjuster, raise the temperature to 80°C, and then... Then, add one-third of the aqueous solution of a water-soluble initiator consisting of 4 parts persulfate and 50 parts water. After nucleation in 20 minutes, a blue seed emulsion is obtained. 3) Add the remaining two-thirds of the mixed monomers from step 1), the remaining two-thirds of the aqueous solution of the water-soluble initiator from step 2), and the remaining 50 parts of 2-acrylamide-2-methylpropanesulfonic acid dropwise simultaneously and slowly. After the addition is completed in 2-3 hours, continue the reaction for about 2-3 hours. Adjust the pH of the system to 7.5±0.1 with a pH adjuster. Then, add 12 parts of preservative, 3 parts of sodium hexametaphosphate, and 15 parts of water in sequence. Filter to obtain the final product.

[0055] Comparative Example 1: The difference between this comparative example and Example 1 is that the emulsion used to prepare the liquid is FS320, a commercially available emulsion for preparing polymer cement waterproof coatings. All other components and their amounts are the same as in Example 1. Under these conditions, significant whitening occurs in a low-temperature, high-humidity environment, as shown in the figure below.

[0056] Comparative Example 2: The difference between this comparative example and Example 1 is that the quartz sand used to prepare the powder is coarser, with a fineness distribution of 36.8% remaining on a 70-mesh sieve and 44.2% remaining on a 140-mesh sieve, which is not within the scope of this claim. All other components and their amounts are the same as in Example 1. Under these conditions, a slight whitening occurs in a low-temperature, high-humidity environment, as shown in the figure below.

[0057] test:

[0058] Performance testing: The tensile properties, bond strength, solid content, and impermeability of the examples and comparative examples were tested according to the performance testing methods in GB / T 23445-2009 "Polymer Cement Waterproof Coatings". The results met the requirements of GB / T 23445-2009. The specific results are shown in Appendix 2.

[0059] Application and Construction: To verify the resistance to alkali efflorescence under low temperature and high humidity conditions, construction verification was carried out in an environment with a temperature of 8-12℃, humidity above 80%, and no ventilation. The specific construction effects of the examples and comparative examples are shown in Appendix 2 and... Figure 1 :

[0060] Appendix 1. Composition and proportions (by weight) of an example of an anti-alkali efflorescence polymer cement waterproof coating suitable for low temperature and high humidity environments:

[0061]

[0062] Appendix 2 Performance of an alkali-resistant polymer cement waterproof coating suitable for low-temperature and high-humidity environments:

[0063]

[0064] Based on the test results and construction effects of the above embodiments and comparative examples, it can be seen that the technical solution of the present invention improves both the liquid and powder components. The styrene-acrylic emulsion used to prepare the liquid component is endowed with excellent chelating properties, low-limit inhibition, and lattice distortion through comprehensive means, thereby preventing the precipitation of calcium carbonate. Combined with the reasonable composition of each raw material in the powder component, especially the strict control of the amount of silicate cement added, and the selection of 70-140 mesh quartz sand with a reasonable particle size distribution of coarse and fine particles, the resulting coating film is dense, reducing the migration channels of the coating film, thereby further reducing the precipitation of calcium carbonate and other substances. As a result, the polymer cement waterproof coating has both good mechanical properties and strong resistance to efflorescence and construction adaptability.

Claims

1. An anti-alkali efflorescence polymer cement waterproof coating suitable for low temperature and high humidity environments, characterized in that, This waterproof coating includes liquid and powder components: The liquid component, by weight, comprises: 92-96 parts of styrene-acrylic emulsion, 0.05-0.2 parts of dispersant, 0.1-0.3 parts of defoamer, 0.2-0.4 parts of primary preservative, 0.1-0.3 parts of hydrophobic modified alkali-swelling thickener, and 4-8 parts of water; By weight, the powder comprises: 30-40 parts of 42.5 ordinary Portland cement, 40-50 parts of 70-140 mesh quartz sand, and 10-30 parts of 200 mesh heavy calcium carbonate. The liquid and powder should be mixed and stirred evenly at a mass ratio of 1:1.4~1.6 before use. The preparation method of the styrene-acrylic emulsion is as follows, according to the parts by weight: 1) First, add 6-12 parts of phosphoric acid emulsifier, 9-18 parts of anionic / anionic emulsifier composed of sodium dodecyl sulfonate, and 300-360 parts of water to the reactor and stir evenly. While stirring, slowly add one-third of a mixture of 60-100 parts of methyl methacrylate or styrene, 320-400 parts of n-butyl acrylate, and 44-52 parts of crosslinking monomers. The crosslinking monomers are one or more of maleic anhydride, trimethylamine ethyl methacrylate, or hydroxypropyl acrylate. While stirring, raise the temperature and pre-disperse at 50°C for 30 minutes to obtain a milky white pre-emulsion. 2) Adjust the pH value to 7-8 with a pH adjuster, raise the temperature to 80℃, and then add one-third of an aqueous solution of a water-soluble initiator consisting of 3-6 parts of persulfate and 30-50 parts of water. After nucleation for 20 minutes, a blue seed emulsion is obtained. 3) Slowly add the remaining two-thirds of the mixed monomers from step 1), the remaining two-thirds of the water-soluble initiator aqueous solution from step 2), and 30-50 parts of the functional monomers simultaneously. After the addition is completed in 2-3 hours, continue the reaction for another 2-3 hours. Adjust the pH of the system to 7.5±0.1 with a pH adjuster. Then add 8-12 parts of the second preservative, 2-4 parts of the additive, and 15-25 parts of water in sequence. Filter to obtain a styrene-acrylic emulsion for polymer cement waterproof coating with anti-efflorescence properties. The phosphoric acid emulsifier is one of alkylphenol polyoxyethylene ether phosphate and sodium isooctanol polyoxyethylene ether phosphate; The functional monomer is 2-acrylamide-2-methylpropanesulfonic acid; The added additive is an aqueous solution of sodium hexametaphosphate.

2. The alkali-resistant polymer cement waterproof coating suitable for low-temperature and high-humidity environments according to claim 1, characterized in that, The fineness requirements for the 70-140 mesh quartz sand are as follows: the residue on the sieve after screening with superimposed 70 mesh and 140 mesh sieves is ≤10% for 70 mesh and ≥75% for 140 mesh.

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