A low-temperature resistant polymer cement-based waterproof coating, its preparation method and application

Abstract

This invention relates to a low-temperature resistant polymer cement-based waterproof coating, its preparation method, and its application. The coating consists of component A and component B. When used, components A and B are mixed in a mass ratio of 1:(0.5-2). Component A includes the following raw materials in parts by weight: 100-150 parts of ethylene-vinyl acetate copolymer emulsion, 10-20 parts of water-based nitrile latex, 2-5 parts of film-forming aid, 3-5 parts of plasticizer, 1-3 parts of defoamer, and 20-50 parts of deionized water. Component B includes the following raw materials in parts by weight: 100-150 parts of silicate cement, 50-60 parts of magnesium phosphate cement, 10-20 parts of gelatin-sodium alginate-coated n-tetradecane phase change microcapsules, and 10-20 parts of citric acid. This coating has advantages such as fast curing, good low-temperature flexibility, and strong freeze-thaw resistance.

Description

Technical Field

[0001] This invention relates to the field of polymer cement-based waterproof coating technology, specifically to a low-temperature resistant polymer cement-based waterproof coating, its preparation method, and its application. Background Technology

[0002] Polymer cement-based waterproof coating, also known as JS waterproof coating, is a two-component waterproof coating mainly composed of water-based polymer emulsion and cement. The two components must be mixed evenly on-site until a fine paste is formed, which can then be brushed or sprayed onto the substrate. After curing, it forms a flexible yet high-strength waterproof layer. This coating combines the high strength and adhesion to damp substrates of cement-based materials with the excellent elasticity and waterproof performance of polymer films. Notably, its water-based system effectively avoids the environmental pollution that may be caused by asphalt, tar, and organic solvents, making it a green, environmentally friendly, non-toxic, and easy-to-apply waterproof material. Since polymer cement-based waterproof coating was recommended as a preferred material, it has been widely used in various fields such as building exterior walls, roofs, kitchens, bathrooms, underground facilities, and bridges.

[0003] However, this coating still faces challenges in practical applications, especially in low-temperature application environments. Because waterborne polymer emulsions are highly sensitive to temperature changes, and the proportion of polymer emulsion is often reduced to control costs, the coating cures slowly at low temperatures, exhibits decreased flexibility, and has limited resistance to freeze-thaw cycles, making it difficult to adapt to low-temperature environments for extended periods. This problem is particularly pronounced in frigid northern regions.

[0004] In summary, current polymer cement-based waterproof coatings have significant shortcomings in low-temperature construction performance, such as slow curing, insufficient flexibility, and limited freeze-thaw resistance. Therefore, it is particularly urgent and important to develop a low-temperature resistant polymer cement-based waterproof coating that can adapt to low-temperature environments. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a low-temperature resistant polymer cement-based waterproof coating, its preparation method, and its application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a low-temperature resistant polymer cement-based waterproof coating, the coating being composed of component A and component B; when used, component A and component B are mixed in a mass ratio of 1:(0.5-2);

[0008] Component A comprises the following raw materials in parts by weight: 100-150 parts of ethylene-vinyl acetate copolymer emulsion (EVA emulsion), 10-20 parts of water-based nitrile latex, 2-5 parts of film-forming aid, 3-5 parts of plasticizer, 1-3 parts of defoamer, and 20-50 parts of deionized water.

[0009] Component B comprises the following raw materials in parts by weight: 100-150 parts silicate cement, 50-60 parts magnesium phosphate cement, 10-20 parts phase change microcapsules, and 10-20 parts sodium citrate.

[0010] The wall material of the phase change microcapsule is a composite of gelatin and sodium alginate, and the core material is n-tetradecane.

[0011] n-Tetradecane is a commonly used phase change material with a high latent heat of phase change and a suitable phase change temperature. To improve its stability, this invention uses gelatin-sodium alginate as a wall material to encapsulate n-tetradecane to form a stable microcapsule structure. This microcapsule not only retains the phase change characteristics of n-tetradecane but also improves its stability and durability through the protective effect of the wall material. n-Tetradecane (C14) undergoes a phase change at around 5°C and has a high latent heat of phase change. When the ambient temperature drops below the phase change temperature, C14 changes from a liquid to a solid state, releasing a large amount of latent heat. In low-temperature environments, free water in cement-based materials easily freezes and expands in volume, leading to internal stress and potentially causing cracks. The addition of n-tetradecane can absorb and store the latent heat released due to water freezing through its phase change process, thereby slowing down or preventing the freezing process. In this way, C14 effectively prevents material damage caused by water freezing and expansion, improving the low-temperature resistance of cement.

[0012] Gelatin, as an effective air-introducing agent, can form tiny pores in cement paste. These pores act as buffer spaces during freeze-thaw cycles, reducing internal pressure caused by the expansion of water upon freezing, thereby minimizing crack formation and improving the low-temperature resistance of the cement. Sodium alginate, a water-soluble polymer, contains numerous hydroxyl and carboxyl groups in its molecular structure, which can react with Mg in magnesium phosphate cement. 2+ A cross-linking reaction occurs, forming a three-dimensional network structure that fills the pores in the polymer cement-based waterproof coating, increasing the material's density and reducing the space for moisture penetration and ice expansion at low temperatures, thus enhancing the material's low-temperature resistance. Therefore, this invention selects gelatin and sodium alginate as the wall materials of the microcapsules. The two exhibit a significant synergistic effect in the waterproof coating, enabling it to better resist moisture penetration, ice expansion, and stress concentration at low temperatures, thereby significantly improving the material's low-temperature resistance.

[0013] At the same time, sodium citrate can also react with Mg in magnesium phosphate cement. 2+Chelation occurs, forming a new phase that gives polymer cement-based waterproof coatings higher mechanical strength and better water resistance.

[0014] Specifically, the preparation method of the phase change microcapsules includes the following steps:

[0015] (1) Add sodium alginate and gelatin to distilled water and stir until dissolved to obtain sodium alginate solution and gelatin solution;

[0016] (2) Add n-tetradecane and emulsifier to the gelatin solution and mix well to obtain an emulsion;

[0017] (3) Slowly add sodium alginate solution to the emulsion to adjust the pH to 3.0-4.0 to obtain a mixed solution;

[0018] (4) Add calcium chloride solution to the mixed solution, stir to solidify, let stand, remove the supernatant, wash with distilled water, remove most of the solvent by rotary evaporation under reduced pressure, filter the precipitated solid, wash, and vacuum dry to obtain gelatin-sodium alginate-coated n-tetradecane phase change microcapsules.

[0019] The mass ratio of n-tetradecane to emulsifier is 1:(0.1-0.3), and the mass ratio of n-tetradecane, gelatin solution and sodium alginate solution is 1:(1-2):(1-2).

[0020] Preferably, the emulsifier in step (2) is Tween-80.

[0021] Preferably, in step (3), a glacial acetic acid solution with a mass concentration of 10-20% is added to adjust the pH.

[0022] Preferably, in step (4), the mass concentration of the sodium alginate solution is 70-80%, the mass concentration of the gelatin solution is 70-80%, the mass concentration of the calcium chloride solution is 70-80%, and the amount of calcium chloride solution added is 40-50 wt% of the mixed solution.

[0023] Preferably, the film-forming aid is propylene glycol methyl ether acetate.

[0024] Preferably, the plasticizer is at least one selected from dioctyl sebacate, dioctyl adipate, and dioctyl terephthalate.

[0025] Preferably, the defoamer is an organosilicon defoamer.

[0026] In a second aspect, the present invention provides a method for preparing the low-temperature resistant polymer cement-based waterproof coating provided in the first aspect, comprising the following steps:

[0027] S1. The ethylene-vinyl acetate copolymer emulsion, water-based nitrile latex, film-forming aid, plasticizer, defoamer and deionized water in the prescribed amounts are stirred and mixed, and then filled to obtain component A;

[0028] S2. Place the formulated amounts of silicate cement, magnesium phosphate cement, phase change microcapsules, and sodium citrate into a powder mixing vessel and stir to mix, thereby obtaining component B.

[0029] Preferably, in step S1, the stirring speed is 5000-8000 r / min and the time is 2-4 h.

[0030] Preferably, in step S2, the stirring speed is 60-100 r / min and the stirring time is 4-8 h.

[0031] Thirdly, the present invention provides the application of the low-temperature resistant polymer cement-based waterproof coating described in the first aspect in the preparation of outdoor building coatings.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] The polymer cement-based waterproof coating of this invention uses ethylene-vinyl acetate copolymer emulsion (EVA emulsion) and water-based nitrile latex as polymers, silicate cement and magnesium phosphate cement as cement-based cementitious materials, and incorporates gelatin-sodium alginate-encapsulated n-tetradecane phase change microcapsules and sodium citrate. Encapsulating n-tetradecane within microcapsules not only preserves its phase change properties but also enhances its stability and durability through the protective effect of the wall material. Furthermore, as a phase change material, n-tetradecane can absorb and store the latent heat released due to water freezing, thereby mitigating or inhibiting the formation of latent heat. The process of stopping water freezing prevents material damage caused by water expansion upon freezing, thus improving the low-temperature resistance of cement. Gelatin, as an effective air-introducing agent, can form tiny pores in the cement paste. These pores can act as buffers in low-temperature environments, thereby improving the freeze-thaw resistance of cement materials. Sodium alginate improves the density and uniformity of the material by forming a three-dimensional network structure. The addition of phase change microcapsules allows the waterproof coating to better resist problems such as water penetration, freezing expansion, and stress concentration at low temperatures, thus significantly improving the low-temperature resistance of the material. Sodium citrate, through its interaction with Mg... 2+ Chelation improves the density of the coating, thereby enhancing its mechanical strength and water resistance. This invention's polymer cement-based waterproof coating, through the addition of phase change microcapsules and sodium citrate, possesses advantages such as rapid curing, good low-temperature flexibility, and strong freeze-thaw resistance. Detailed Implementation

[0034] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0035] The materials used in the following embodiments and comparative examples are sourced from the following sources:

[0036] Ethylene-vinyl acetate copolymer emulsion: Manufacturer: Wuhan Jiyesheng Chemical Co., Ltd., Product No.: A0060;

[0037] Water-based nitrile butadiene latex: Manufacturer: Dongguan Mingyuan Plastics Co., Ltd., Product No.: JB15, Solid content: ≥43.5%, pH: 7.5-9.0, Viscosity: 15-80 mPa·s (room temperature), Acrylonitrile content: approximately 35% (based on monomer components).

[0038] Propylene glycol methyl ether acetate: Manufacturer: Guangdong Wengjiang Chemical Reagent Co., Ltd., Model: PB04652;

[0039] Dioctyl sebacate: Manufacturer: Guangdong Wengjiang Chemical Reagent Co., Ltd., Model: PB14028;

[0040] Dioctyl adipic acid: Manufacturer: Guangzhou Yuanda New Materials Co., Ltd.

[0041] Dioctyl terephthalate: Manufacturer: Guangzhou Yuanda New Materials Co., Ltd.

[0042] Gelatin: Manufacturer: Guangdong Wengjiang Chemical Reagent Co., Ltd., Model: PA00256;

[0043] Sodium alginate: Manufacturer is Shanghai Haohong Biomedical Technology Co., Ltd., model number is 1087623;

[0044] Gum arabic: Manufacturer: Guangdong Wengjiang Chemical Reagent Co., Ltd., Model: PA37901;

[0045] Chitosan: Manufacturer: Shanghai Aladdin Biochemical Technology Co., Ltd., Model: C105799, Deacetylation degree: ≥95%;

[0046] Tween-80: Manufacturer is Guangdong Wengjiang Chemical Reagent Co., Ltd., model number is PB01659;

[0047] Defoamer: Organosilicon defoamer, manufactured by Dow Chemical Company, model AFE-1410;

[0048] Silicate cement: Manufacturer is Hubei Jusheng Technology Co., Ltd., product number is JS4427;

[0049] Magnesium phosphate cement: The manufacturer is Guizhou Phosphorus Magnesium Materials Co., Ltd., and the product numbers are A and B. When using this invention, A and B need to be mixed in a 1:1 mass ratio.

[0050] Sodium citrate: Manufacturer: Shanghai Haohong Biomedical Technology Co., Ltd., Model No. 1067252, Purity: 98%.

[0051] Unless otherwise specified, all other materials, reagents, etc. used in the examples and comparative examples are commercially available.

[0052] Example 1

[0053] A low-temperature resistant polymer cement-based waterproof coating, the coating being composed of component A and component B; component A comprises the following raw materials in parts by weight: 125 parts of ethylene-vinyl acetate copolymer emulsion, 13 parts of water-based nitrile latex, 4 parts of film-forming aid, 4 parts of plasticizer, 2 parts of defoamer, and 30 parts of deionized water.

[0054] Component B comprises the following raw materials in parts by weight: 130 parts silicate cement, 55 parts magnesium phosphate cement, 16 parts phase change microcapsules, and 15 parts sodium citrate.

[0055] The film-forming aid is propylene glycol methyl ether acetate, the plasticizer is dioctyl sebacate and dioctyl adipate in a mass ratio of 1:1, and the defoamer is an organosilicone defoamer.

[0056] The method for preparing the phase change microcapsules includes the following steps:

[0057] (1) Add sodium alginate and gelatin to distilled water and stir until dissolved to obtain sodium alginate solution and gelatin solution;

[0058] (2) Add n-tetradecane and emulsifier to the gelatin solution and mix well to obtain an emulsion;

[0059] (3) Slowly add sodium alginate solution to the emulsion, and adjust the pH to 3.5 by adding 15% glacial acetic acid solution to obtain a mixed solution;

[0060] (4) Add calcium chloride solution to the mixed solution, stir to solidify, let stand, remove the supernatant, wash with distilled water, remove most of the solvent by rotary evaporation under reduced pressure, filter the precipitated solid, wash, and vacuum dry to obtain the gelatin-sodium alginate-coated n-tetradecane phase change microcapsules.

[0061] The emulsifier is Tween-80, the mass ratio of n-tetradecane to emulsifier is 1:0.2, the mass ratio of n-tetradecane, gelatin solution and sodium alginate solution is 1:1.5:2, the mass concentration of sodium alginate solution in step (1) is 75%, the mass concentration of gelatin solution is 75%, and the mass concentration of calcium chloride solution in step (4) is 75% and the amount of calcium chloride solution added is 45 wt% of the mixed solution.

[0062] A method for preparing a low-temperature resistant polymer cement-based waterproof coating includes the following steps:

[0063] S1. The ethylene-vinyl acetate copolymer emulsion, water-based nitrile latex, film-forming aid, plasticizer, defoamer and deionized water in the prescribed amounts are stirred at a speed of 6000 r / min for 3 h, and then filled to obtain component A.

[0064] S2. The specified amounts of silicate cement, magnesium phosphate cement, phase change microcapsules, and sodium citrate are placed in a powder mixing kettle and stirred at 80 r / min for 6 h to obtain component B.

[0065] Example 2

[0066] A low-temperature resistant polymer cement-based waterproof coating, the coating being composed of component A and component B; component A comprises the following raw materials in parts by weight: 100 parts of ethylene-vinyl acetate copolymer emulsion, 10 parts of water-based nitrile latex, 2 parts of film-forming aid, 3 parts of plasticizer, 1 part of defoamer, and 20 parts of deionized water.

[0067] Component B comprises the following raw materials in parts by weight: 100 parts silicate cement, 50 parts magnesium phosphate cement, 10 parts phase change microcapsules, and 10 parts sodium citrate.

[0068] The film-forming aid is propylene glycol methyl ether acetate, the plasticizer is dioctyl adipate, and the defoamer is an organosilicone defoamer.

[0069] The method for preparing the phase change microcapsules includes the following steps:

[0070] (1) Add sodium alginate and gelatin to distilled water and stir until dissolved to obtain sodium alginate solution and gelatin solution;

[0071] (2) Add n-tetradecane and emulsifier to the gelatin solution and mix well to obtain an emulsion;

[0072] (3) Slowly add sodium alginate solution to the emulsion, and adjust the pH to 4.0 by adding 10% glacial acetic acid solution to obtain a mixed solution;

[0073] (4) Add calcium chloride solution to the mixed solution, stir to solidify, let stand, remove the supernatant, wash with distilled water, remove most of the solvent by rotary evaporation under reduced pressure, filter the precipitated solid, wash, and vacuum dry to obtain the gelatin-sodium alginate-coated n-tetradecane phase change microcapsules.

[0074] The emulsifier is Tween-80, the mass ratio of n-tetradecane to emulsifier is 1:0.1, the mass ratio of n-tetradecane, gelatin solution and sodium alginate solution is 1:1:1, the mass concentration of sodium alginate solution in step (1) is 70%, the mass concentration of gelatin solution is 70%, and the mass concentration of calcium chloride solution in step (4) is 70%, and the amount of calcium chloride solution added is 40 wt% of the mixed solution.

[0075] A method for preparing a low-temperature resistant polymer cement-based waterproof coating includes the following steps:

[0076] S1. The ethylene-vinyl acetate copolymer emulsion, water-based nitrile latex, film-forming aid, plasticizer, defoamer and deionized water in the prescribed amounts are stirred at a speed of 5000 r / min for 4 h, and then filled to obtain component A.

[0077] S2. The specified amounts of silicate cement, magnesium phosphate cement, phase change microcapsules, and sodium citrate are placed in a powder mixing reactor and stirred at 60 r / min for 8 h to obtain component B.

[0078] Example 3

[0079] A low-temperature resistant polymer cement-based waterproof coating, the coating being composed of component A and component B;

[0080] Component A comprises the following raw materials in parts by weight: 150 parts of ethylene-vinyl acetate copolymer emulsion, 20 parts of water-based nitrile latex, 5 parts of film-forming aid, 5 parts of plasticizer, 3 parts of defoamer, and 50 parts of deionized water.

[0081] Component B comprises the following raw materials in parts by weight: 150 parts silicate cement, 60 parts magnesium phosphate cement, 20 parts phase change microcapsules, and 20 parts sodium citrate.

[0082] The film-forming aid is propylene glycol methyl ether acetate, the plasticizer is dioctyl terephthalate, and the defoamer is an organosilicone defoamer.

[0083] The method for preparing the phase change microcapsules includes the following steps:

[0084] (1) Add sodium alginate and gelatin to distilled water and stir until dissolved to obtain sodium alginate solution and gelatin solution;

[0085] (2) Add n-tetradecane and emulsifier to the gelatin solution and mix well to obtain an emulsion;

[0086] (3) Slowly add sodium alginate solution to the emulsion, and adjust the pH to 3.0 by adding 20% ​​glacial acetic acid solution to obtain a mixed solution;

[0087] (4) Add calcium chloride solution to the mixed solution, stir to solidify, let stand, remove the supernatant, wash with distilled water, remove most of the solvent by rotary evaporation under reduced pressure, filter the precipitated solid, wash, and vacuum dry to obtain the gelatin-sodium alginate-coated n-tetradecane phase change microcapsules.

[0088] The emulsifier is Tween-80, the mass ratio of n-tetradecane to emulsifier is 1:0.3, the mass ratio of n-tetradecane, gelatin solution and sodium alginate solution is 1:2:2, the mass concentration of sodium alginate solution in step (1) is 80%, the mass concentration of gelatin solution is 80%, and the mass concentration of calcium chloride solution in step (4) is 80%, and the amount of sodium chloride solution added is 50 wt% of the mixed solution.

[0089] A method for preparing a low-temperature resistant polymer cement-based waterproof coating includes the following steps:

[0090] S1. The ethylene-vinyl acetate copolymer emulsion, water-based nitrile latex, film-forming aid, plasticizer, defoamer and deionized water in the prescribed amounts are stirred at 8000 r / min for 2 h, and then filled to obtain component A.

[0091] S2. The specified amounts of silicate cement, magnesium phosphate cement, phase change microcapsules, and sodium citrate are placed in a powder mixing kettle and stirred at 100 r / min for 4 h to obtain component B.

[0092] Comparative Example 1

[0093] The difference between Comparative Example 1 and Example 1 is that phase change microcapsules are not added, and equal amounts of gelatin, sodium alginate and n-tetradecane are directly added to component B.

[0094] Comparative Example 2

[0095] The difference between Comparative Example 2 and Example 1 is that gelatin-gum arabic is used instead of gelatin-sodium alginate to coat n-tetradecane. The specific preparation steps are as follows:

[0096] (1) Add gum arabic and gelatin to distilled water and stir until dissolved to obtain gum arabic solution and gelatin solution;

[0097] (2) Add n-tetradecane and emulsifier to the gum arabic solution and mix well to obtain an emulsion;

[0098] (3) Slowly add gelatin solution to emulsion, and adjust pH to 3.5 by adding 15% glacial acetic acid solution to obtain mixed solution;

[0099] (4) Add calcium chloride solution to the mixed solution, stir to solidify, let stand, remove the supernatant, wash with distilled water, remove most of the solvent by rotary evaporation under reduced pressure, filter the precipitated solid, wash, and vacuum dry to obtain the gelatin-gum arabic coated n-tetradecane phase change microcapsules.

[0100] The emulsifier is Tween-80, the mass ratio of n-tetradecane to emulsifier is 1:0.2, the mass ratio of n-tetradecane, gelatin solution and gum arabic solution is 1:1.5:2, the mass concentration of sodium alginate solution in step (1) is 75%, the mass concentration of gelatin solution is 75%, and the mass concentration of calcium chloride solution in step (4) is 75%, and the amount of calcium chloride solution added is 45 wt% of the mixed solution.

[0101] Comparative Example 3

[0102] The difference between Comparative Example 3 and Example 1 is that, instead of using gelatin-sodium alginate to coat n-tetradecane, sodium alginate-chitosan was used to coat n-tetradecane. The specific preparation steps are as follows:

[0103] (1) Add sodium alginate and chitosan to distilled water and stir until dissolved to obtain sodium alginate solution and chitosan solution;

[0104] (2) Add n-tetradecane and emulsifier to sodium alginate solution, mix well to obtain emulsion;

[0105] (3) Slowly add chitosan solution to the emulsion, and adjust the pH to 3.5 by adding 15% glacial acetic acid solution to obtain a mixed solution;

[0106] (4) Add calcium chloride solution to the mixed solution, stir to solidify, let stand, remove the supernatant, wash with distilled water, remove most of the solvent by rotary evaporation under reduced pressure, filter the precipitated solid, wash, and vacuum dry to obtain sodium alginate-chitosan-coated n-tetradecane phase change microcapsules.

[0107] The emulsifier is Tween-80, the mass ratio of n-tetradecane to emulsifier is 1:0.2, the mass ratio of n-tetradecane, chitosan and sodium alginate is 1:1.5:2, the mass concentration of sodium alginate solution in step (1) is 75%, the mass concentration of chitosan solution is 75%, and the mass concentration of calcium chloride solution in step (4) is 75%, and the amount of calcium chloride solution added is 45 wt% of the mixed solution.

[0108] Comparative Example 4

[0109] The difference between Comparative Example 4 and Example 1 is that: Comparative Example 4 does not add magnesium phosphate cement, and the reduced mass is allocated to the mass of silicate cement, phase change microcapsules and sodium citrate in the same proportion as in Example 1.

[0110] Comparative Example 5

[0111] The difference between Comparative Example 5 and Example 1 is that Comparative Example 5 does not add sodium citrate, and the reduced mass is allocated to the mass of silicate cement, magnesium phosphate cement, and phase change microcapsules in the same proportion as in Example 1.

[0112] Comparative Example 6

[0113] The difference between Comparative Example 6 and Example 1 is that Comparative Example 3 does not add silicate cement, and the reduced mass is allocated to the mass of magnesium phosphate cement, sodium citrate, and phase change microcapsules in the same proportion as in Example 1.

[0114] Comparative Example 7

[0115] The difference between Comparative Example 7 and Example 1 is that Comparative Example 3 does not add phase change microcapsules, and the reduced mass is distributed to the mass of silicate cement, magnesium phosphate cement and sodium citrate in the same proportion as in Example 1.

[0116] Performance testing

[0117] The polymer cement-based waterproof coatings obtained in Examples 1-3 and Comparative Examples 1-7 were mixed with component A and component B at a mass ratio of 1:1 and then roller-coated. The surface drying time and actual drying time at -5℃, tensile strength, elongation at break, bond strength, low-temperature flexibility, and resistance to freeze-thaw damage were tested in accordance with GB / T23445-2009 "Polymer Cement Waterproof Coatings" and JC / T975-2005 "Waterproof Coatings for Roads and Bridges". The specific results are shown in Table 1.

[0118] Table 1 Performance test data of polymer cementitious waterproof coating

[0119]

[0120]

[0121] As shown in Table 1, Comparative Example 1, which directly added gelatin, sodium alginate, and n-tetradecane to the system, exhibited inferior mechanical properties, low-temperature resistance, alkali resistance, and hydrophobicity compared to Example 1. This is likely because the small size and uniform dispersion of the phase change microcapsules in Example 1 allowed them to distribute more evenly within the cement matrix, avoiding agglomeration and uneven distribution that might occur with direct addition. This uniform distribution contributes to improving the mechanical properties and durability of cement-based materials. Furthermore, in microcapsule form, n-tetradecane can exist stably within the cement-based material and exert its heat storage and temperature regulation function, thereby improving the low-temperature resistance of the cement material.

[0122] Comparative Example 2 replaced sodium alginate in the microcapsule material with gum arabic, and Comparative Example 3 replaced gelatin in the microcapsule material with chitosan. The mechanical properties, low-temperature resistance, alkali resistance, and hydrophobic properties of Comparative Examples 2 and 3 were all inferior to those of Example 1. This may be because gelatin can form tiny pores in the cement paste to reduce the internal pressure caused by the expansion of water upon freezing, thereby reducing crack formation and improving the low-temperature resistance of the cement material. Sodium alginate, on the other hand, can react with Mg in magnesium phosphate cement. 2+ A cross-linking reaction occurs, forming a three-dimensional network structure that fills the pores in the polymer cement-based waterproof coating, increasing the material's density and reducing the space for moisture penetration and ice expansion at low temperatures, thus enhancing the material's low-temperature resistance. Therefore, this invention selects sodium alginate and gelatin as encapsulating materials; their synergistic effect effectively improves the material's mechanical properties and low-temperature resistance.

[0123] Comparative Examples 4-7, without the addition of silicate cement, magnesium phosphate cement, sodium citrate, and phase change microcapsules, showed significantly lower performance than Example 1. This indicates that silicate cement, magnesium phosphate cement, sodium citrate, and phase change microcapsules may have a synergistic effect, which may have a synergistic effect on the mechanical strength, water resistance, and low-temperature resistance of the waterproof coating.

[0124] In summary, the polymer cement-based waterproof coating of the present invention has the advantages of fast curing, good low-temperature flexibility, and strong freeze-thaw resistance.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A low-temperature resistant polymer cement-based waterproof coating, characterized in that, The coating consists of component A and component B; when used, component A and component B are mixed at a mass ratio of 1:(0.5-2). Component A comprises the following raw materials in parts by weight: 100-150 parts of ethylene-vinyl acetate copolymer emulsion, 10-20 parts of water-based nitrile latex, 2-5 parts of film-forming aid, 3-5 parts of plasticizer, 1-3 parts of defoamer, and 20-50 parts of deionized water; wherein the film-forming aid is propylene glycol methyl ether acetate, the plasticizer is at least one of dioctyl sebacate, dioctyl adipate, and dioctyl terephthalate, the defoamer is an organosilicon defoamer, and the emulsifier is Tween-80; Component B comprises the following raw materials in parts by weight: 100-150 parts silicate cement, 50-60 parts magnesium phosphate cement, 10-20 parts phase change microcapsules, and 10-20 parts sodium citrate. The wall material of the phase change microcapsule is a composite of gelatin and sodium alginate, and the core material is n-tetradecane. The method for preparing the phase change microcapsules includes the following steps: (1) Add sodium alginate and gelatin to distilled water and stir until dissolved to obtain sodium alginate solution and gelatin solution; (2) Add n-tetradecane and emulsifier to the gelatin solution and mix well to obtain an emulsion; (3) Slowly add sodium alginate solution to the emulsion to adjust the pH to 3.0-4.0 to obtain a mixed solution; (4) Add calcium chloride solution to the mixed solution, stir to solidify, let stand, remove the supernatant, wash with distilled water, remove most of the solvent by rotary evaporation under reduced pressure, filter the precipitated solid, wash, and vacuum dry to obtain gelatin-sodium alginate-coated n-tetradecane phase change microcapsules. The mass ratio of n-tetradecane to emulsifier is 1:(0.1-0.3), and the mass ratio of n-tetradecane, gelatin solution and sodium alginate solution is 1:(1-2):(1-2).

2. The low-temperature resistant polymer cement-based waterproof coating as described in claim 1, characterized in that, In step (3) of the preparation of the phase change microcapsules, a glacial acetic acid solution with a mass concentration of 10-20% is added to adjust the pH.

3. The low-temperature resistant polymer cement-based waterproof coating as described in claim 1, characterized in that, The sodium alginate solution has a mass concentration of 70-80%, the gelatin solution has a mass concentration of 70-80%, the calcium chloride solution has a mass concentration of 70-80%, and the amount of calcium chloride solution added is 40-50 wt% of the mixed solution.

4. The method for preparing the low-temperature resistant polymer cement-based waterproof coating according to any one of claims 1-3, characterized in that, Includes the following steps: S1. The ethylene-vinyl acetate copolymer emulsion, water-based nitrile latex, film-forming aid, plasticizer, defoamer and deionized water in the prescribed amounts are stirred and mixed, and then filled to obtain component A; S2. Place the formulated amounts of silicate cement, magnesium phosphate cement, phase change microcapsules, and sodium citrate into a powder mixing vessel and stir to mix, thereby obtaining component B.

5. The method for preparing the low-temperature resistant polymer cement-based waterproof coating as described in claim 4, characterized in that, In step S1, the stirring speed is 5000-8000 r / min, and the time is 2-4 h.

6. The method for preparing the low-temperature resistant polymer cement-based waterproof coating as described in claim 4, characterized in that, In step S2, the stirring speed is 60-100 r / min and the stirring time is 4-8 h.

7. The application of the low-temperature resistant polymer cement-based waterproof coating according to any one of claims 1-3 in the preparation of outdoor building coatings.

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