Waterproof coating for building exterior wall and preparation method thereof

Abstract

The invention relates to the technical field of waterproof coatings, and in particular to a waterproof coating for building exterior walls and a preparation method thereof. The waterproof coating comprises the following raw materials in parts by weight: 50-60 parts of vinyl acetate-ethylene copolymer emulsion, 10-15 parts of composite emulsion, 0.1-0.3 parts of dispersant, 0.3-0.5 parts of defoamer, 0.8-1 parts of film-forming aid, 58-62 parts of cement, 30-35 parts of heavy calcium carbonate and 30-35 parts of quartz powder. The composite emulsion is added into the raw materials of the waterproof coating, and a polymer in the composite emulsion has a special semi-interpenetrating network structure with a polyrotaxane structure as a cross-linking point, and a perfluorinated chain segment and a siloxane group are introduced, so as to solve the problem of low bonding strength between the existing waterproof coating for building exterior walls and a concrete substrate, and at the same time improve the mechanical properties of the waterproof coating, and reduce the mechanical property loss caused by aging.

Description

Technical Field

[0001] The present invention relates to the technical field of waterproof coatings, and in particular to a waterproof coating for building exterior walls and a preparation method thereof. Background Art

[0002] In recent years, external wall leakage has become the biggest common quality problem of newly built buildings. The erosion of walls by water, especially the penetration into the walls through cracks, can cause rust of the steel bars inside the concrete and accelerate the carbonization of concrete. In severe cases, it can affect the service life of the building.

[0003] At present, the commonly used waterproof coatings only form a coating of a certain thickness on the surface of concrete, and the bonding strength between these coatings and the damp concrete substrate is not high. The material and the substrate are prone to obvious interface defects, resulting in overall peeling and loss of waterproof effect. At the same time, because the exterior walls of buildings are exposed to water, atmosphere, sunlight and chemical erosion all year round, the coating of the waterproof coating ages, resulting in a decrease in its physical and mechanical properties, which in turn affects its waterproof performance. Summary of the invention

[0004] The purpose of the present invention is to provide a waterproof coating for building exterior walls and a preparation method thereof, which solves the problem of low bonding strength between the existing waterproof coating for building exterior walls and the concrete substrate, while improving the mechanical properties of the waterproof coating and reducing the loss of its mechanical properties due to aging.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A method for preparing a waterproof coating for building exterior walls comprises the following steps: Step S1: weighing the following raw materials in parts by weight: 50-60 parts of vinyl acetate-ethylene copolymer emulsion, 10-15 parts of composite emulsion, 0.1-0.3 parts of dispersant, 0.3-0.5 parts of defoamer, 0.8-1 parts of film-forming aid, 58-62 parts of cement, 30-35 parts of heavy calcium carbonate and 30-35 parts of quartz powder;

[0007] Step S2: mixing vinyl acetate-ethylene copolymer emulsion, composite emulsion, dispersant, defoamer and film-forming aid, stirring to obtain liquid material, mixing cement, heavy calcium carbonate and quartz powder to obtain powder material, slowly adding the liquid material into the powder material, stirring at a stirring rate of 800-1000rpm for 8-10min, to obtain a waterproof coating for building exterior walls;

[0008] The composite emulsion is prepared by the following steps: weighing the following raw materials in parts by weight: 40-45 parts of a modified polymer, 0.5-0.8 parts of sodium lauryl sulfate and 60-70 parts of deionized water, mixing the modified polymer, sodium lauryl sulfate and deionized water, and stirring for 30 minutes at a stirring rate of 2000 rpm and a temperature of 30° C. to prepare a composite emulsion;

[0009] The modified polymer is prepared by the following steps:

[0010] Step A1: 3-aminopropyltriethoxysilane and 4-methoxyphenol were mixed, stirred at a stirring rate of 200-240 rpm and a temperature of 40° C., and hydroxyethyl acrylate was added thereto for a reaction of 5-6 hours to obtain an intermediate 1;

[0011] The ratio of 3-aminopropyltriethoxysilane, hydroxyethyl acrylate and 4-methoxyphenol is 0.1 mol: 0.2-0.22 mol: 2-2.3 g;

[0012] During the reaction, the amino group in 3-aminopropyltriethoxysilane and the double bond in hydroxyethyl acrylate undergo Michael addition to form a tertiary amine to obtain intermediate 1;

[0013] Step A2: isophorone diisocyanate and polyether diol are mixed, and the mixture is reacted for 2-3 hours under nitrogen protection, a stirring rate of 150-180 rpm, and a temperature of 90° C., and then intermediate 1, 1,4-butanediol and dihydroxymethylpropionic acid are added, and the reaction is continued for 2-3 hours, and then hydroxyethyl methacrylate is added, and the reaction is continued for 1 hour, and the temperature is lowered to 50° C. and triethylamine is added, and the reaction is continued for 30 minutes to obtain a capped prepolymer;

[0014] The amount ratio of isophorone diisocyanate, polyether diol, intermediate 1, 1,4-butanediol, dimethylol propionic acid, hydroxyethyl methacrylate and triethylamine is 0.07-0.08 mol: 26-27 g: 0.008-0.01 mol: 0.03-0.032 mol: 0.012-0.013 mol: 0.004 mol: 0.015 mol;

[0015] During the reaction, the isocyanate group in isophorone diisocyanate first reacts with the hydroxyl group in the polyether diol, then reacts with the hydroxyl group in the intermediate 1,1,4-butanediol and dimethylol propionic acid, and then hydroxyethyl methacrylate is added for end-capping, and then triethylamine is added for neutralization, thereby obtaining an acrylate-terminated end-capped prepolymer.

[0016] Step A3: mixing the end-capped prepolymer, the modified polyrotaxane, methyl methacrylate, butyl acrylate and N,N-dimethylformamide, stirring at a stirring rate of 300-400 rpm and a temperature of 80° C., adding potassium persulfate, and reacting for 3-4 hours to obtain a modified polymer;

[0017] The amount ratio of the end-capped prepolymer, the modified polyrotaxane, methyl methacrylate, butyl acrylate, potassium persulfate and N,N-dimethylformamide is 120-140 g: 18-20 g: 7-8 g: 7-8 g: 0.25-0.28 g: 80-100 mL;

[0018] During the reaction, under the action of potassium persulfate as an initiator, free radical polymerization of double bonds in the end-capped prepolymer, modified polyrotaxane, methyl methacrylate and butyl acrylate occurs to form polyacrylate segments, thereby obtaining a modified polymer.

[0019] The modified polyrotaxane is prepared by the following steps:

[0020] Step B1: 4-bromo-1,8-naphthalene dicarboxylic anhydride and anhydrous ethanol are mixed, and 1H,1H-perfluorooctylamine is added under nitrogen protection, stirring at a rate of 300-400 rpm and a temperature of 80°C, and the mixture is reacted for 3-4 hours to obtain intermediate a. Intermediate a is mixed with N,N-dimethylformamide, and sodium azide and deionized water are added under stirring at a rate of 180-200 rpm and room temperature, and the mixture is reacted for 16-18 hours to obtain intermediate b.

[0021] The ratio of 4-bromo-1,8-naphthalene dicarboxylic anhydride to 1H,1H-perfluorooctylamine is 0.02 mol: 0.02-0.022 mol, and the ratio of intermediate a, sodium azide and deionized water is 0.02 mol: 0.37-0.4 g: 2 mL;

[0022] During the reaction, the anhydride in 4-bromo-1,8-naphthalene dicarboxylic anhydride reacts with the amino group in 1H,1H-perfluorooctylamine to form an imide structure to obtain intermediate a. The bromine in intermediate a is then azidated under the action of sodium azide to form an azide group to obtain intermediate b.

[0023] Step B2: β-cyclodextrin, itaconic acid and anhydrous ethanol are mixed, and the mixture is reacted for 1-1.5 hours at a stirring rate of 150-180 rpm and a temperature of 80°C to obtain modified cyclodextrin. Polyethylene glycol and tetrahydrofuran are mixed, and potassium tert-butoxide is added under nitrogen protection at a stirring rate of 200-300 rpm and a temperature of 5°C, and the mixture is stirred and reacted for 1 hour. Propylene bromide is then added dropwise and the mixture is heated to room temperature. The reaction is continued for 24 hours to obtain modified polyethylene glycol.

[0024] The ratio of β-cyclodextrin to itaconic acid is 0.02 mol: 0.01-0.011 mol, and the ratio of polyethylene glycol, potassium tert-butoxide and propyne bromide is 100-110 g: 0.12-0.13 mol: 0.12-0.13 mol;

[0025] During the reaction, the hydroxyl group in β-cyclodextrin and the carboxyl group in itaconic acid undergo esterification reaction to form an ester bond to obtain modified cyclodextrin, and the terminal hydroxyl group in polyethylene glycol first forms a potassium salt under the action of potassium tert-butoxide, which then undergoes a substitution reaction with the bromine in bromopropyne to obtain a terminal acetylenic group-modified polyethylene glycol;

[0026] Step B3: Mix the modified polyethylene glycol, modified cyclodextrin and deionized water and disperse them ultrasonically for 10-15 minutes, stir them for 12 hours at room temperature under nitrogen protection and at a stirring rate of 400-500 rpm, then add intermediate b, copper sulfate pentahydrate, pentamethyldiethylenetriamine and sodium ascorbate, and react for 2-3 hours to obtain a modified polyrotaxane;

[0027] The amount ratio of modified polyethylene glycol, modified cyclodextrin, intermediate b, copper sulfate pentahydrate, pentamethyldiethylenetriamine and sodium ascorbate is 10-11 g: 0.008-0.01 mol: 0.02-0.22 mol: 4.5-5 g: 0.001 mol: 0.002 mol;

[0028] In the reaction process, the modified polyethylene glycol is used as the guest and the modified cyclodextrin is used as the host. A polyrotaxane structure is formed by the threading method. Then, the terminal alkyne group in the modified polyethylene glycol reacts with the click reaction group of the azide group in the intermediate b to form a triazole group, which is used to cap the polyrotaxane structure and obtain a modified polyrotaxane.

[0029] Beneficial effects of the invention: The invention relates to a waterproof coating for building exterior walls and a preparation method thereof. By adding a composite emulsion into the raw materials of the waterproof coating, the problem of low bonding strength between the existing waterproof coating for building exterior walls and the concrete substrate is solved, and at the same time, the mechanical properties of the waterproof coating are improved, and the mechanical property loss caused by aging is reduced; the composite emulsion is prepared with modified polymer, sodium dodecyl sulfate and deionized water as raw materials, and the modified polymer is prepared by free radical polymerization of end-capped prepolymer, modified polyrotaxane, methyl methacrylate and butyl acrylate. Since the modified polyrotaxane is prepared by threading modified cyclodextrin on modified polyethylene glycol, the structure formed by the modified cyclodextrin can rotate and slide on the main chain of the modified polyethylene glycol, and since polyacrylate segments are polymerized on the modified cyclodextrin by free radical polymerization, a semi-interpenetrating network structure formed by combining non-covalent crosslinking and covalent crosslinking is formed. This special network structure not only maintains the waterproof coating The cross-linking density of the material after curing makes it have good waterproof performance. At the same time, the movable molecular chain structure makes it have good toughness. Since this toughness comes from its physical structure, the aging caused by ultraviolet radiation has little effect on its mechanical properties, so that the waterproof coating can still maintain good mechanical properties after ultraviolet aging. At the same time, since the modified polyrotaxane is terminated with intermediate b, intermediate b is grafted with a perfluorinated long chain, this long chain can improve the waterproof performance of the coating to a certain extent, and since 3-aminopropyltriethoxysilane side chains are introduced into the end-capped prepolymer, during the curing process of the coating, the Si-0-Si bond formed after hydrolysis also improves its waterproof performance to a certain extent. At the same time, it also participates in the curing process of cement and inorganic filler in the waterproof coating, so that the various components of the waterproof coating can still maintain good compatibility. At the same time, the polyacrylate segment in the composite emulsion can also produce good bonding performance between the waterproof coating and the concrete substrate. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely below. 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, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Embodiment 1 A method for preparing a waterproof coating for building exterior walls comprises the following steps: Step S1: Weigh the following raw materials in parts by weight: 50 parts of commercially available DA-102H vinyl acetate-ethylene copolymer emulsion, 10 parts of composite emulsion, 0.1 parts of 5040 dispersant, 0.3 parts of NXZ defoamer, 0.8 parts of dodecyl alcohol ester film-forming aid, 58 parts of Wannianqing P·042.5 cement, 30 parts of Yongshun 800 mesh heavy calcium carbonate and 30 parts of commercially available Shifeng 200 mesh quartz powder;

[0032] Step S2: mixing vinyl acetate-ethylene copolymer emulsion, composite emulsion, dispersant, defoamer and film-forming aid, stirring to obtain liquid material, mixing cement, heavy calcium carbonate and quartz powder to obtain powder material, slowly adding the liquid material into the powder material, stirring at a stirring rate of 800 rpm for 10 minutes, and obtaining a waterproof coating for building exterior walls;

[0033] The composite emulsion is prepared by the following steps: weighing the following raw materials by weight: 40 parts of modified polymer, 0.5 parts of sodium lauryl sulfate and 70 parts of deionized water, mixing the modified polymer, sodium lauryl sulfate and deionized water, stirring at a stirring rate of 2000 rpm and a temperature of 30° C. for 30 minutes to prepare a composite emulsion;

[0034] The modified polymer is prepared by the following steps:

[0035] Step A1: 3-aminopropyltriethoxysilane and 4-methoxyphenol were mixed, stirred at a stirring rate of 200 rpm and a temperature of 40° C., and hydroxyethyl acrylate was added thereto for a reaction of 5 h to obtain an intermediate 1;

[0036] The amount ratio of 3-aminopropyltriethoxysilane, hydroxyethyl acrylate and 4-methoxyphenol is 0.1 mol: 0.2 mol: 2 g;

[0037] Step A2: isophorone diisocyanate and DL1000 polyether diol were mixed, and the mixture was reacted for 2 h under nitrogen protection, stirring at a rate of 150 rpm and a temperature of 90° C., and then the intermediate 1, 1,4-butanediol and dimethylolpropionic acid were added, and the reaction was continued for 2 h, and then hydroxyethyl methacrylate was added, and the reaction was continued for 1 h, and the temperature was lowered to 50° C. and triethylamine was added, and the reaction was continued for 30 min to obtain a capped prepolymer;

[0038] The amount ratio of isophorone diisocyanate, polyether diol, intermediate 1, 1,4-butanediol, dimethylol propionic acid, hydroxyethyl methacrylate and triethylamine is 0.07 mol: 26 g: 0.008 mol: 0.03-0.032 mol: 0.012 mol: 0.004 mol: 0.015 mol;

[0039] Step A3: mixing the end-capped prepolymer, the modified polyrotaxane, methyl methacrylate, butyl acrylate and N,N-dimethylformamide, stirring at a stirring rate of 300-400 rpm and a temperature of 80° C., adding potassium persulfate, and reacting for 3-4 hours to obtain a modified polymer;

[0040] The amount ratio of the end-capped prepolymer, the modified polyrotaxane, methyl methacrylate, butyl acrylate, potassium persulfate and N,N-dimethylformamide is 120 g: 18 g: 7 g: 7 g: 0.28 g: 80 mL;

[0041] The modified polyrotaxane is prepared by the following steps:

[0042] Step B1: 4-bromo-1,8-naphthalene dicarboxylic anhydride and anhydrous ethanol were mixed, and 1H,1H-perfluorooctylamine was added under nitrogen protection, stirring at a rate of 300 rpm and a temperature of 80°C, and the mixture was reacted for 3 hours to obtain intermediate a. Intermediate a was mixed with N,N-dimethylformamide, and sodium azide and deionized water were added under stirring at a rate of 180 rpm and room temperature, and the mixture was reacted for 16 hours to obtain intermediate b.

[0043] The ratio of 4-bromo-1,8-naphthalene dicarboxylic anhydride to 1H,1H-perfluorooctylamine is 0.02 mol:0.02 mol, and the ratio of intermediate a, sodium azide and deionized water is 0.02 mol:0.37 g:2 mL;

[0044] Step B2: β-cyclodextrin, itaconic acid and anhydrous ethanol were mixed, and the mixture was reacted for 1 h at a stirring rate of 150 rpm and a temperature of 80°C to obtain modified cyclodextrin. PEG2000 polyethylene glycol and tetrahydrofuran were mixed, and potassium tert-butoxide was added under nitrogen protection at a stirring rate of 200 rpm and a temperature of 5°C, and the mixture was stirred for 1 h. Propylene bromide was then added dropwise and the mixture was heated to room temperature. The reaction was continued for 24 h to obtain modified polyethylene glycol.

[0045] The ratio of β-cyclodextrin to itaconic acid is 0.02 mol: 0.01 mol, and the ratio of polyethylene glycol, potassium tert-butoxide and propyne bromide is 100 g: 0.12 mol: 0.12 mol;

[0046] Step B3: Modified polyethylene glycol, modified cyclodextrin and deionized water were mixed and ultrasonically dispersed for 10 minutes, stirred at a stirring rate of 400 rpm under nitrogen protection and room temperature for 12 hours, and then intermediate b, copper sulfate pentahydrate, pentamethyldiethylenetriamine and sodium ascorbate were added and reacted for 2 hours to obtain a modified polyrotaxane;

[0047] The amount ratio of modified polyethylene glycol, modified cyclodextrin, intermediate b, copper sulfate pentahydrate, pentamethyldiethylenetriamine and sodium ascorbate is 10g: 0.008mol: 0.02mol: 4.5g: 0.001mol: 0.002mol.

[0048] Embodiment 2 A method for preparing a waterproof coating for building exterior walls comprises the following steps: Step S1: Weigh the following raw materials in parts by weight: 60 parts of commercially available DA-102H vinyl acetate-ethylene copolymer emulsion, 10 parts of composite emulsion, 0.3 parts of 5040 dispersant, 0.5 parts of NXZ defoamer, 1 part of dodecyl alcohol ester film-forming aid, 62 parts of Wannianqing P·042.5 cement, 35 parts of Yongshun 800 mesh heavy calcium carbonate and 35 parts of commercially available Shifeng 200 mesh quartz powder;

[0049] Step S2: mixing vinyl acetate-ethylene copolymer emulsion, composite emulsion, dispersant, defoamer and film-forming aid, stirring to obtain liquid material, mixing cement, heavy calcium carbonate and quartz powder to obtain powder material, slowly adding the liquid material into the powder material, stirring at a stirring rate of 1000 rpm for 8 minutes, and obtaining a waterproof coating for building exterior walls;

[0050] The composite emulsion is prepared by the following steps: weighing the following raw materials by weight: 40 parts of modified polymer, 0.8 parts of sodium lauryl sulfate and 60 parts of deionized water, mixing the modified polymer, sodium lauryl sulfate and deionized water, stirring at a stirring rate of 2000 rpm and a temperature of 30° C. for 30 minutes to prepare a composite emulsion;

[0051] The modified polymer is prepared by the following steps:

[0052] Step A1: 3-aminopropyltriethoxysilane and 4-methoxyphenol were mixed, stirred at a stirring rate of 240 rpm and a temperature of 40° C., and hydroxyethyl acrylate was added thereto for a reaction of 5 h to obtain an intermediate 1;

[0053] The ratio of 3-aminopropyltriethoxysilane, hydroxyethyl acrylate and 4-methoxyphenol is 0.1 mol: 0.22 mol: 2 g;

[0054] Step A2: isophorone diisocyanate and DL1000 polyether diol were mixed, and the mixture was reacted for 3 hours under nitrogen protection, a stirring rate of 150 rpm, and a temperature of 90° C., and then the intermediate 1, 1,4-butanediol and dimethylol propionic acid were added, and the reaction was continued for 3 hours, and then hydroxyethyl methacrylate was added, and the reaction was continued for 1 hour, and the temperature was lowered to 50° C. and triethylamine was added, and the reaction was continued for 30 minutes to obtain a capped prepolymer;

[0055] The amount ratio of isophorone diisocyanate, polyether diol, intermediate 1, 1,4-butanediol, dimethylol propionic acid, hydroxyethyl methacrylate and triethylamine is 0.07 mol: 27 g: 0.008 mol: 0.032 mol: 0.012 mol: 0.004 mol: 0.015 mol;

[0056] Step A3: the end-capped prepolymer, the modified polyrotaxane, methyl methacrylate, butyl acrylate and N,N-dimethylformamide were mixed, and potassium persulfate was added under stirring conditions of a stirring rate of 400 rpm and a temperature of 80° C., and the mixture was reacted for 3 h to obtain a modified polymer;

[0057] The amount ratio of the end-capped prepolymer, the modified polyrotaxane, methyl methacrylate, butyl acrylate, potassium persulfate and N,N-dimethylformamide is 120g:20g:8g:8g:0.25g:100mL;

[0058] The modified polyrotaxane is prepared by the following steps:

[0059] Step B1: 4-bromo-1,8-naphthalene dicarboxylic anhydride and anhydrous ethanol were mixed, and 1H,1H-perfluorooctylamine was added under nitrogen protection, stirring at a rate of 400 rpm and a temperature of 80°C, and the mixture was reacted for 3 hours to obtain intermediate a. Intermediate a was mixed with N,N-dimethylformamide, and sodium azide and deionized water were added under stirring at a rate of 200 rpm and room temperature, and the mixture was reacted for 16 hours to obtain intermediate b.

[0060] The ratio of 4-bromo-1,8-naphthalene dicarboxylic anhydride to 1H,1H-perfluorooctylamine is 0.02 mol: 0.022 mol, and the ratio of intermediate a, sodium azide and deionized water is 0.02 mol: 0.37 g: 2 mL;

[0061] Step B2: β-cyclodextrin, itaconic acid and anhydrous ethanol were mixed, and the mixture was reacted for 1 h at a stirring rate of 180 rpm and a temperature of 80°C to obtain modified cyclodextrin. PEG2000 polyethylene glycol and tetrahydrofuran were mixed, and potassium tert-butoxide was added under nitrogen protection at a stirring rate of 300 rpm and a temperature of 5°C, and the mixture was stirred for 1 h. Propylene bromide was then added dropwise and the mixture was heated to room temperature. The reaction was continued for 24 h to obtain modified polyethylene glycol.

[0062] The ratio of β-cyclodextrin to itaconic acid is 0.02 mol: 0.01 mol, and the ratio of polyethylene glycol, potassium tert-butoxide and propyne bromide is 110 g: 0.12 mol: 0.12 mol;

[0063] Step B3: Modified polyethylene glycol, modified cyclodextrin and deionized water were mixed and ultrasonically dispersed for 15 minutes, stirred for 12 hours at room temperature under nitrogen protection and a stirring rate of 400 rpm, and then intermediate b, copper sulfate pentahydrate, pentamethyldiethylenetriamine and sodium ascorbate were added and reacted for 3 hours to obtain a modified polyrotaxane;

[0064] The usage ratio of modified polyethylene glycol, modified cyclodextrin, intermediate b, copper sulfate pentahydrate, pentamethyldiethylenetriamine and sodium ascorbate is 11 g: 0.008 mol: 0.22 mol: 4.5 g: 0.001 mol: 0.002 mol.

[0065] Embodiment 3 A method for preparing a waterproof coating for building exterior walls comprises the following steps: Step S1: Weigh the following raw materials in parts by weight: 60 parts of commercially available DA-102H vinyl acetate-ethylene copolymer emulsion, 15 parts of composite emulsion, 0.3 parts of 5040 dispersant, 0.5 parts of NXZ defoamer, 1 part of dodecyl alcohol ester film-forming aid, 62 parts of Wan Nianqing P·O42.5 cement, 35 parts of Yongshun 800 mesh heavy calcium carbonate and 35 parts of commercially available Shifeng 200 mesh quartz powder;

[0066] Step S2: mixing vinyl acetate-ethylene copolymer emulsion, composite emulsion, dispersant, defoamer and film-forming aid, stirring to obtain liquid material, mixing cement, heavy calcium carbonate and quartz powder to obtain powder material, slowly adding the liquid material into the powder material, stirring at a stirring rate of 1000 rpm for 10 minutes, and obtaining a waterproof coating for building exterior walls;

[0067] The composite emulsion is prepared by the following steps: weighing the following raw materials by weight: 45 parts of a modified polymer, 0.8 parts of sodium lauryl sulfate and 70 parts of deionized water, mixing the modified polymer, sodium lauryl sulfate and deionized water, stirring at a stirring rate of 2000 rpm and a temperature of 30° C. for 30 minutes to prepare a composite emulsion;

[0068] The modified polymer is prepared by the following steps:

[0069] Step A1: 3-aminopropyltriethoxysilane and 4-methoxyphenol were mixed, stirred at a stirring rate of 240 rpm and a temperature of 40° C., and hydroxyethyl acrylate was added thereto for a reaction of 6 h to obtain an intermediate 1;

[0070] The ratio of 3-aminopropyltriethoxysilane, hydroxyethyl acrylate and 4-methoxyphenol is 0.1 mol: 0.22 mol: 2.3 g;

[0071] Step A2: isophorone diisocyanate and DL1000 polyether diol were mixed, and the mixture was reacted for 3 hours under nitrogen protection, stirring at a rate of 180 rpm and a temperature of 90° C., and then the intermediate 1, 1,4-butanediol and dimethylolpropionic acid were added, and the reaction was continued for 3 hours, and then hydroxyethyl methacrylate was added, and the reaction was continued for 1 hour, and the temperature was lowered to 50° C. and triethylamine was added, and the reaction was continued for 30 minutes to obtain a capped prepolymer;

[0072] The amount ratio of isophorone diisocyanate, polyether diol, intermediate 1, 1,4-butanediol, dimethylol propionic acid, hydroxyethyl methacrylate and triethylamine is 0.08 mol: 27 g: 0.01 mol: 0.032 mol: 0.013 mol: 0.004 mol: 0.015 mol;

[0073] Step A3: the end-capped prepolymer, the modified polyrotaxane, methyl methacrylate, butyl acrylate and N,N-dimethylformamide were mixed, and potassium persulfate was added under stirring conditions of a stirring rate of 400 rpm and a temperature of 80° C., and the mixture was reacted for 4 hours to obtain a modified polymer;

[0074] The amount ratio of the end-capped prepolymer, the modified polyrotaxane, methyl methacrylate, butyl acrylate, potassium persulfate and N,N-dimethylformamide is 140g:20g:8g:8g:0.28g:100mL;

[0075] The modified polyrotaxane is prepared by the following steps:

[0076] Step B1: 4-bromo-1,8-naphthalene dicarboxylic anhydride and anhydrous ethanol were mixed, and 1H,1H-perfluorooctylamine was added under nitrogen protection, stirring at a rate of 400 rpm and a temperature of 80°C, and the mixture was reacted for 4 hours to obtain intermediate a. Intermediate a was mixed with N,N-dimethylformamide, and sodium azide and deionized water were added under stirring at a rate of 200 rpm and room temperature, and the mixture was reacted for 18 hours to obtain intermediate b.

[0077] The ratio of 4-bromo-1,8-naphthalene dicarboxylic anhydride to 1H,1H-perfluorooctylamine is 0.02 mol: 0.022 mol, and the ratio of intermediate a, sodium azide and deionized water is 0.02 mol: 0.4 g: 2 mL;

[0078] Step B2: β-cyclodextrin, itaconic acid and anhydrous ethanol were mixed, and the mixture was reacted for 1.5 hours at a stirring rate of 180 rpm and a temperature of 80°C to obtain modified cyclodextrin. PEG2000 polyethylene glycol and tetrahydrofuran were mixed, and potassium tert-butoxide was added under nitrogen protection at a stirring rate of 300 rpm and a temperature of 5°C, and the mixture was stirred and reacted for 1 hour. Propylene bromide was then added dropwise and the mixture was heated to room temperature. The reaction was continued for 24 hours to obtain modified polyethylene glycol.

[0079] The ratio of β-cyclodextrin to itaconic acid is 0.02 mol: 0.011 mol, and the ratio of polyethylene glycol, potassium tert-butoxide and propyne bromide is 110 g: 0.13 mol: 0.13 mol;

[0080] Step B3: Modified polyethylene glycol, modified cyclodextrin and deionized water were mixed and ultrasonically dispersed for 15 minutes, stirred for 12 hours at room temperature under nitrogen protection and a stirring rate of 500 rpm, and then intermediate b, copper sulfate pentahydrate, pentamethyldiethylenetriamine and sodium ascorbate were added and reacted for 3 hours to obtain a modified polyrotaxane;

[0081] The amount ratio of modified polyethylene glycol, modified cyclodextrin, intermediate b, copper sulfate pentahydrate, pentamethyldiethylenetriamine and sodium ascorbate is 11g: 0.01mol: 0.22mol: 5g: 0.001mol: 0.002mol.

[0082] Comparative Example 1 Compared with Example 3, this comparative example is to remove the intermediate 1 in the preparation process of the modified polymer in Example 3, and the other steps are the same.

[0083] Comparative Example 2 Compared with Example 3, this comparative example is characterized in that hydroxyethyl methacrylate in the preparation process of the modified polymer in Example 3 is replaced by ethanol, and the other steps are the same.

[0084] Comparative Example 3 Compared with Example 3, this comparative example is characterized in that 1H,1H-perfluorooctylamine in the preparation process of the modified polyrotaxane in Example 3 is replaced by ethylamine, and the other steps are the same.

[0085] Comparative Example 4 In this comparative example, compared with Example 3, the modified polyrotaxane in the preparation process of the modified polymer in Example 3 is replaced by the modified cyclodextrin in Example 3, and the other steps are the same.

[0086] The waterproof coatings for building exterior walls prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were applied twice on a concrete substrate, with a coating interval of 12 h and a coating thickness of 1.5 mm. The concrete substrate was pre-moistened and then placed at a temperature of 23 ° C and a humidity of 50% for 96 h, demolded, and dried to obtain a sample, which was cut into a sample block with a size of 90 mm × 25 mm × 1.5 mm, according to GB / T 16777-2008, tensile properties are tested, the sample is placed at 80℃ for 168h, the tensile properties after heat aging are tested, and the retention rate of tensile properties after heat aging is calculated to evaluate its heat aging resistance, the sample is placed in a saturated solution of 0.1% mass fraction of sodium hydroxide and calcium hydroxide for 168h, the tensile properties after alkali aging are tested, and the retention rate of tensile properties after alkali aging is calculated to evaluate its alkali aging resistance, the sample is placed in a UV box, at 45℃, UV aging for 240h, the tensile properties after UV aging are tested, and the retention rate of tensile properties after UV aging is calculated to evaluate its UV aging resistance, refer to GB / T 23445-2009, a coating with a size of 40mm×40mm×1.5mm is prepared on a substrate, cured for 96h under standard experimental conditions, and dried at 40℃ for 48h, the bonding strength is tested, refer to GB / T 23445-2009, the anti-seepage performance of the samples after heat aging and UV aging was tested. The anti-seepage performance was determined by whether water permeability occurred under the conditions of 0.7MPa pressure and 2h time to evaluate its waterproof performance. The test results are as follows:

[0087]

[0088] It can be seen from the test results in the table shown that Example 1, Example 2 and Example 3 are compared with Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4. In Comparative Example 1, the intermediate 1 is removed during the preparation of the modified polymer in Example 3. Due to the lack of silane side chains, its anti-permeability and bonding strength are reduced. In Comparative Example 2, hydroxyethyl methacrylate is replaced with ethanol during the preparation of the modified polymer in Example 3. Since there is no chemical bond connection between the modified polyrotaxane and the end-capped prepolymer, the lack of a semi-interpenetrating network structure causes a significant decrease in its tensile properties under ultraviolet aging conditions, and at the same time, the tensile properties and anti-permeability properties are also significantly reduced. In Comparative Example 3, 1H, 1H-perfluorooctylamine is replaced with ethylamine during the preparation of the modified polyrotaxane in Example 3. Due to the lack of a perfluoro long chain, its anti-permeability is significantly reduced. In Comparative Example 4, the modified polyrotaxane in the preparation of the modified polymer in Example 3 is replaced with the modified cyclodextrin in Example 3. Due to the lack of a semi-interpenetrating network structure, its various properties are significantly reduced.

[0089] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. 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 can be combined in any one or more embodiments or examples in a suitable manner.

[0090] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a waterproof coating for building exterior walls, characterized in that: The method comprises the following steps: Step S1: weighing the following raw materials in parts by weight: 50-60 parts of vinyl acetate-ethylene copolymer emulsion, 10-15 parts of composite emulsion, 0.1-0.3 parts of dispersant, 0.3-0.5 parts of defoamer, 0.8-1 parts of film-forming aid, 58-62 parts of cement, 30-35 parts of heavy calcium carbonate and 30-35 parts of quartz powder; Step S2: mixing vinyl acetate-ethylene copolymer emulsion, composite emulsion, dispersant, defoamer and film-forming aid, stirring to obtain liquid material, mixing cement, heavy calcium carbonate and quartz powder to obtain powder material, slowly adding the liquid material into the powder material, stirring at a stirring rate of 800-1000rpm for 8-10min, to obtain a waterproof coating for building exterior walls; The composite emulsion is prepared by the following steps: weighing the following raw materials in parts by weight: 40-45 parts of a modified polymer, 0.5-0.8 parts of sodium lauryl sulfate and 60-70 parts of deionized water, mixing the modified polymer, sodium lauryl sulfate and deionized water, and stirring for 30 minutes at a stirring rate of 2000 rpm and a temperature of 30° C. to prepare a composite emulsion; The modified polymer is prepared by the following steps: Step A1: 3-aminopropyltriethoxysilane and 4-methoxyphenol were mixed, stirred at a stirring rate of 200-240 rpm and a temperature of 40° C., and hydroxyethyl acrylate was added thereto for a reaction of 5-6 hours to obtain an intermediate 1; Step A2: isophorone diisocyanate and polyether diol are mixed, and the mixture is reacted for 2-3 hours under nitrogen protection, a stirring rate of 150-180 rpm, and a temperature of 90° C., and then intermediate 1, 1,4-butanediol and dihydroxymethylpropionic acid are added, and the reaction is continued for 2-3 hours, and then hydroxyethyl methacrylate is added, and the reaction is continued for 1 hour, and the temperature is lowered to 50° C. and triethylamine is added, and the reaction is continued for 30 minutes to obtain a capped prepolymer; Step A3: mixing the end-capped prepolymer, the modified polyrotaxane, methyl methacrylate, butyl acrylate and N,N-dimethylformamide, stirring at a stirring rate of 300-400 rpm and a temperature of 80° C., adding potassium persulfate, and reacting for 3-4 hours to obtain a modified polymer; In step A1: the ratio of 3-aminopropyltriethoxysilane, hydroxyethyl acrylate and 4-methoxyphenol is 0.1 mol: 0.2-0.22 mol: 2-2.3 g; In step A2: the amount ratio of isophorone diisocyanate, polyether diol, intermediate 1, 1,4-butanediol, dimethylolpropionic acid, hydroxyethyl methacrylate and triethylamine is 0.07-0.08 mol: 26-27 g: 0.008-0.01 mol: 0.03-0.032 mol: 0.012-0.013 mol: 0.004 mol: 0.015 mol; In step A3: the amount ratio of the end-capped prepolymer, the modified polyrotaxane, methyl methacrylate, butyl acrylate, potassium persulfate and N,N-dimethylformamide is 120-140 g: 18-20 g: 7-8 g: 7-8 g: 0.25-0.28 g: 80-100 mL; The modified polyrotaxane is prepared by the following steps: Step B1: 4-bromo-1,8-naphthalene dicarboxylic anhydride and anhydrous ethanol are mixed, and 1H,1H-perfluorooctylamine is added under nitrogen protection, stirring at a rate of 300-400 rpm and a temperature of 80°C, and the mixture is reacted for 3-4 hours to obtain intermediate a. Intermediate a is mixed with N,N-dimethylformamide, and sodium azide and deionized water are added under stirring at a rate of 180-200 rpm and room temperature, and the mixture is reacted for 16-18 hours to obtain intermediate b. Step B2: β-cyclodextrin, itaconic acid and anhydrous ethanol are mixed, and the mixture is reacted for 1-1.5 hours at a stirring rate of 150-180 rpm and a temperature of 80°C to obtain modified cyclodextrin. Polyethylene glycol and tetrahydrofuran are mixed, and potassium tert-butoxide is added under nitrogen protection at a stirring rate of 200-300 rpm and a temperature of 5°C, and the mixture is stirred and reacted for 1 hour. Propylene bromide is then added dropwise and the mixture is heated to room temperature. The reaction is continued for 24 hours to obtain modified polyethylene glycol. Step B3: Mix the modified polyethylene glycol, modified cyclodextrin and deionized water and disperse them ultrasonically for 10-15 minutes, stir them for 12 hours at room temperature under nitrogen protection and at a stirring rate of 400-500 rpm, then add intermediate b, copper sulfate pentahydrate, pentamethyldiethylenetriamine and sodium ascorbate, and react for 2-3 hours to obtain a modified polyrotaxane; In step B1: the ratio of 4-bromo-1,8-naphthalene dicarboxylic anhydride and 1H,1H-perfluorooctylamine is 0.02 mol: 0.02-0.022 mol, and the ratio of intermediate a, sodium azide and deionized water is 0.02 mol: 0.37-0.4 g: 2 mL; In step B2: the ratio of β-cyclodextrin to itaconic acid is 0.02 mol: 0.01-0.011 mol, and the ratio of polyethylene glycol, potassium tert-butoxide and propyne bromide is 100-110 g: 0.12-0.13 mol: 0.12-0.13 mol.

2. The method for preparing a waterproof coating for building exterior walls according to claim 1, characterized in that: In step B3: the usage ratio of modified polyethylene glycol, modified cyclodextrin, intermediate b, copper sulfate pentahydrate, pentamethyldiethylenetriamine and sodium ascorbate is 10-11 g: 0.008-0.01 mol: 0.02-0.22 mol: 4.5-5 g: 0.001 mol: 0.002 mol.

3. A waterproof coating for building exterior walls, characterized in that: Prepared according to any one of the preparation methods described in claims 1-2.

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