Water-based two-component waterproof coating for drinking water and water storage tanks

Abstract

This invention discloses a water-based two-component waterproof coating for drinking water and water storage tanks, relating to the field of waterproof coatings. The water-based two-component waterproof coating for drinking water and water storage tanks comprises component A, component B, and water, wherein the weight ratio of component A, component B, and water is 1:(2-2.2):(0.6-0.9). Component A includes the following raw materials in parts by weight: 80-100 parts of polyol; 20-24 parts of diphenylmethane diisocyanate; and 1-2 parts of stabilizer. Component B includes the following raw materials in parts by weight: 25-35 parts of plasticizer; 2.5-3.2 parts of chain extender; 55-70 parts of filler; 9-13 parts of CO2 absorbent; and 0.1-0.3 parts of catalyst. The polyurethane waterproof coating prepared in this application is environmentally friendly, exhibits excellent water resistance and mechanical properties, and meets the environmental requirements of projects such as drinking water tanks and water storage tanks.

Description

Technical Field

[0001] This invention relates to the field of waterproof coatings, and in particular to a water-based two-component waterproof coating for drinking water and water storage tanks. Background Technology

[0002] Waterproof coatings are viscous liquid polymer materials that exhibit no fixed shape at room temperature. After application, they cure on the substrate surface through solvent and moisture evaporation or reaction, forming a tough waterproof membrane. Waterproof coatings are made primarily from synthetic polymers, polymers combined with asphalt, or polymers combined with cement as the main film-forming substances, with the addition of various additives, modifiers, and fillers. They are mainly used on the substrate surfaces of buildings such as roofs, basements, bathrooms, shower rooms, and exterior walls.

[0003] Polyurethane waterproof coating is a commonly used waterproof coating with good elongation, good adhesion, corrosion resistance, high tensile strength, and convenient construction. It is suitable for construction on complex substrates, especially for waterproofing and seepage prevention of roofs, basements, and bathrooms.

[0004] However, ordinary polyurethane waterproof coatings cannot meet the requirements of projects with high environmental protection standards, such as drinking water reservoirs and water storage tanks. Ordinary polyurethane coatings contain a large amount of organic solvents, and the curing agent in two-component polyurethane waterproof coatings often uses MOCA (3,3-dichloro-4,4-diaminodiphenylmethane). These substances remain in the dried coating film and, with long-term use, will be submerged and migrate into the water, affecting water quality and posing a threat to human health. Summary of the Invention

[0005] In order to enable polyurethane waterproof coatings to meet the high environmental protection requirements of projects such as drinking water tanks and water storage tanks, this application provides a water-based two-component waterproof coating for drinking water and water storage tanks.

[0006] The water-based two-component waterproof coating for drinking water and water storage tanks provided in this application adopts the following technical solution:

[0007] A water-based two-component waterproof coating for drinking water and water storage tanks, comprising component A, component B and water, wherein the weight ratio of component A, component B and water is 1:(2-2.2):(0.6-0.9);

[0008] Component A comprises the following raw materials in parts by weight:

[0009] 80-100 parts of polyols;

[0010] 20-24 parts of diphenylmethane diisocyanate;

[0011] Stabilizer 1-2 parts;

[0012] Component B comprises the following raw materials in parts by weight:

[0013] Plasticizer 25-35 parts;

[0014] Chain extender 2.5-3.2 parts;

[0015] 55-70 parts of filler;

[0016] 9-13 parts of CO2 absorbent;

[0017] Catalyst 0.1-0.3 parts.

[0018] Through the above technical solution, in this application, water is used as a curing agent to replace MOCA to grow polyurethane molecular chains and form a coating film. No organic solvents are added to the raw materials. Diphenylmethane diisocyanate is used instead of highly toxic toluene diisocyanate. No dispersants or latent curing agents that may migrate harmful components are added to the raw materials. The resulting waterproof coating is green and environmentally friendly and can be used in projects with high environmental protection requirements, such as drinking water pools and water storage tanks.

[0019] A prepolymer containing -NCO is formed by polyols and diphenylmethane diisocyanate. -NCO reacts with water to form a polymer compound. A chain extender ensures the dispersibility of water in the polyurethane system, improving film-forming properties. A plasticizer enhances the coating's workability, increasing its softness and elasticity. Fillers improve the physical and mechanical properties of the waterproof coating film. A CO2 absorbent absorbs the CO2 gas generated by the reaction of -NCO with water, reducing the formation of bubbles or pinholes in the coating film. Through the synergistic effect of the raw material components, the prepared waterproof coating film has a smooth and even appearance, good uniformity and density, excellent workability, and superior physical and mechanical properties.

[0020] Optionally, the chain extender is selected from one or more of 2,2-dimethylolbutyric acid, trimethylolpropane, polyaspartic acid ester resin and modified polyaspartic acid ester resin.

[0021] Through the above technical solution, the chain extender contains hydrophilic groups, which can promote the compatibility of water and polyurethane prepolymer, promote the chain extension reaction of water and -NCO, generate high molecular polymer, and improve the softness and extensibility of polyurethane polymer.

[0022] Optionally, the chain extender is a mixture of 2,2-dimethylolbutyric acid and modified polyaspartic acid ester resin in a weight ratio of 1:(0.5-0.7), wherein the modified polyaspartic acid ester resin is composed of the following raw materials in parts by weight:

[0023] 2-5 parts of graphene oxide;

[0024] Silane coupling agent KH-550, 25-32 parts;

[0025] 100-110 parts of diethyl maleate;

[0026] 68-75 parts of 4,4'-diaminodicyclohexylmethane.

[0027] Through the above technical solution, 2,2-dihydroxymethylbutyric acid contains two hydroxyl groups and one carboxyl group, which promotes the reaction between water and isocyanate groups; the modified polyaspartic acid ester resin grafts graphene oxide onto the polyaspartic acid ester resin through chemical bonds. The modified polyaspartic acid ester resin has amino groups and introduces graphene oxide, which has a large number of reactive sites, thereby optimizing the structure of the polyurethane system during chain extension, making the molecular arrangement more orderly, the coating film uniform and dense, and thus improving the water resistance, corrosion resistance and tensile properties of the coating film.

[0028] Optionally, the modified polyaspartic ester resin is prepared by the following method:

[0029] Graphene oxide was added to an aqueous ethanol solution, heated to 60-70℃, and stirred thoroughly to obtain a mixture. Silane coupling agent KH-550 and ethanol were mixed evenly to obtain a KH-550 ethanol solution. The KH-550 ethanol solution was added to the mixture, heated to 75-80℃ to react, cooled, centrifuged, and the precipitate was taken, washed, and dried to obtain modified graphene oxide.

[0030] Modified graphene oxide and diethyl maleate were added to a reaction flask, stirred and preheated to 55-60℃, and 4,4'-diaminodicyclohexylmethane was slowly added dropwise. The temperature was raised to 90-100℃ and the reaction was carried out for 10-12 hours to obtain modified polyaspartic acid ester resin.

[0031] The above technical solution first uses silane coupling agent KH-550 to modify graphene oxide. After hydrolysis, the silane reacts with the hydroxyl groups of graphene oxide, and the amino group at the other end reacts with diethyl maleate, thereby achieving a strong bond between graphene oxide and polyaspartic acid ester resin, resulting in good dispersibility and compatibility.

[0032] Optionally, the filler is a mixture of light calcium carbonate and modified kaolin, wherein the weight ratio of light calcium carbonate to modified kaolin is (1.4-1.8):1.

[0033] Through the above technical solutions, the filler plays a reinforcing role and prevents the coating from shrinking in volume due to moisture evaporation. The selection of light calcium carbonate and modified kaolin has good dispersibility in the polyurethane system, resulting in better overall performance of the coating.

[0034] Optionally, the modified kaolin is prepared by the following method:

[0035] Kaolin particles were calcined in a muffle furnace at 500-600℃ and then cooled. Kaolin particles and 6%-10% of polymethylhydrosiloxane by weight were weighed, mixed evenly, and added to a ball mill jar. The mixture was ball-milled for 30-40 minutes using steel balls as the milling medium. The product was repeatedly washed with petroleum ether, centrifuged, and the lower precipitate was collected. The precipitate was then vacuum-dried at 60-75℃ and ground through a 200-mesh sieve to obtain modified kaolin.

[0036] The above technical solution utilizes polymethylhydrosiloxane as a modifier, and modified kaolin is prepared by ball milling. The polymethylhydrosiloxane coats the surface of the kaolin particles, improving the hydrophobic properties and dispersibility of the kaolin in the polyurethane system. By adding modified kaolin to waterproof coatings, the water resistance and tensile properties of the coating film are improved, enhancing its durability and making it suitable for applications requiring long-term immersion in water.

[0037] Optionally, the polyol is selected from one or more of polypropylene glycol PPG2000, polyethylene glycol PEG1000, polyether polyol 330N, and polypropylene glycol PPG4000.

[0038] By using the above technical solution, the uniformity of the coating film is improved by selecting a multifunctional hydrophilic polyether polyol, thereby enhancing the performance of the coating film.

[0039] Optionally, the plasticizer is selected from one or more of chlorinated paraffin, dibutyl phthalate, and tributyl acetyl citrate.

[0040] The above technical solutions and the selection of the above plasticizers meet the environmental protection requirements of waterproof coatings.

[0041] Optionally, the catalyst is selected from one or more of bis(dimethylaminopropyl)isopropanolamine, N-(dimethylaminopropyl)diisopropanolamine, and triethylamine.

[0042] The above technical solution uses amine catalysts instead of lead and tin catalysts to avoid the potential adverse effects of lead and tin catalyst migration on drinking water.

[0043] Optionally, the waterproof coating is prepared by the following steps:

[0044] Synthesis of Component A: The polyol is dehydrated under vacuum, cooled to 60-70℃, and then diphenylmethane diisocyanate and stabilizer are added. The mixture is heated to 85-90℃ and reacted for 2-3 hours. Component A is then obtained by discharging the product.

[0045] Synthesis of Component B: Plasticizer is added to the reactor, the temperature is raised to 90-100℃, filler, chain extender and CO2 absorbent are added, the temperature is raised to 110-120℃ for vacuum dehydration, the temperature is lowered to 50-55℃ for catalyst addition, vacuum degassing, and Component B is discharged.

[0046] Waterproof coating preparation: Mix component A, component B and water according to the weight ratio, stir evenly to obtain waterproof coating.

[0047] The waterproof coating prepared using the above technical solution has good water resistance and tensile properties, and the coating film is uniform and corrosion resistant, making it suitable for drinking water tanks, water storage tanks, and projects that require long-term immersion in water.

[0048] In summary, this application has at least one of the following beneficial effects:

[0049] 1. In this application, water is used as a curing agent to replace MOCA to grow polyurethane molecular chains and form a coating film. No organic solvents are added to the raw materials. Diphenylmethane diisocyanate is used instead of highly toxic toluene diisocyanate. No dispersants or latent curing agents that may migrate harmful components are added to the raw materials. As a result, the prepared waterproof coating is green and environmentally friendly and can be used in projects with high environmental protection requirements such as drinking water pools and water storage tanks.

[0050] 2.2,2-Dihydroxymethylbutyric acid contains two hydroxyl groups and one carboxyl group, which promotes the reaction between water and isocyanate groups; the modified polyaspartic acid ester resin grafts graphene oxide onto the polyaspartic acid ester resin through chemical bonds. The modified polyaspartic acid ester resin has amino groups and introduces graphene oxide. Graphene oxide has a large number of reactive sites, thereby optimizing the structure of the polyurethane system during chain extension, making the molecular arrangement more orderly, the coating film uniform and dense, and thus improving the water resistance, corrosion resistance and tensile properties of the coating film.

[0051] 3. Modified kaolin was prepared by ball milling using polymethylhydrosiloxane as a modifier. The polymethylhydrosiloxane coated the surface of the kaolin particles, improving the hydrophobic properties and dispersibility of the kaolin in the polyurethane system. By adding modified kaolin to waterproof coatings, the water resistance and tensile properties of the coating film are improved, enhancing its durability and making it suitable for applications requiring long-term immersion in water. Detailed Implementation

[0052] The present application will be further described in detail below with reference to Examples 1-6 and Comparative Example 1.

[0053] Preparation Example

[0054] Preparation Example 1

[0055] Preparation of modified polyaspartic acid ester resin

[0056] The modified polyaspartic acid ester resin is composed of the following raw materials:

[0057] 0.2 kg of graphene oxide;

[0058] Silane coupling agent KH-550 2.5kg;

[0059] 10 kg of diethyl maleate;

[0060] 6.8 kg of 4,4'-diaminodicyclohexylmethane.

[0061] Modified polyaspartic acid ester resin was prepared by the following method:

[0062] Graphene oxide was added to 1.5 kg of ethanol-water solution, with a weight ratio of ethanol to water of 1:1. The mixture was heated to 60 °C and stirred thoroughly to obtain a mixture. Silane coupling agent KH-550 and 6 kg of ethanol were mixed evenly to obtain a KH-550 ethanol solution. The KH-550 ethanol solution was added to the mixture, and the mixture was heated to 75 °C and reacted for 12 h. After cooling, the mixture was centrifuged, and the precipitate was washed with acetone and dried under vacuum at 50 °C for 10 h to obtain modified graphene oxide.

[0063] Modified graphene oxide and diethyl maleate were added to a reaction flask, stirred and preheated to 55°C, and 4,4'-diaminodicyclohexylmethane was slowly added dropwise. The addition was completed in 0.5 h, and the temperature was raised to 90°C and reacted for 10 h to obtain modified polyaspartic acid ester resin.

[0064] Preparation Example 2

[0065] Preparation of modified polyaspartic acid ester resin

[0066] The modified polyaspartic acid ester resin is composed of the following raw materials:

[0067] 0.5 kg of graphene oxide;

[0068] Silane coupling agent KH-550 3.2kg;

[0069] 11 kg of diethyl maleate;

[0070] 7.5 kg of 4,4'-diaminodicyclohexylmethane.

[0071] Modified polyaspartic acid ester resin was prepared by the following method:

[0072] Graphene oxide was added to 3 kg of ethanol-water solution, with a weight ratio of ethanol to water of 1:1. The mixture was heated to 70 °C and stirred thoroughly to obtain a mixture. Silane coupling agent KH-550 and 8 kg of ethanol were mixed evenly to obtain a KH-550 ethanol solution. The KH-550 ethanol solution was added to the mixture, and the mixture was heated to 80 °C and reacted for 12 h. After cooling, the mixture was centrifuged, and the precipitate was washed with acetone and dried under vacuum at 50 °C for 10 h to obtain modified graphene oxide.

[0073] Modified graphene oxide and diethyl maleate were added to a reaction flask, stirred and preheated to 60°C, and 4,4'-diaminodicyclohexylmethane was slowly added dropwise. The addition was completed in 0.5 h, and the temperature was raised to 100°C and reacted for 12 h to obtain modified polyaspartic acid ester resin.

[0074] Preparation Example 3

[0075] Preparation of modified polyaspartic acid ester resin

[0076] The modified polyaspartic acid ester resin is composed of the following raw materials:

[0077] 0.3 kg of graphene oxide;

[0078] Silane coupling agent KH-550 2.8kg;

[0079] 10.5 kg of diethyl maleate;

[0080] 7.1 kg of 4,4'-diaminodicyclohexylmethane.

[0081] Modified polyaspartic acid ester resin was prepared by the following method:

[0082] Graphene oxide was added to 2.2 kg of ethanol-water solution, with a weight ratio of ethanol to water of 1:1. The mixture was heated to 65 °C and stirred thoroughly to obtain a mixture. Silane coupling agent KH-550 and 7 kg of ethanol were mixed evenly to obtain a KH-550 ethanol solution. The KH-550 ethanol solution was added to the mixture, and the mixture was heated to 78 °C and reacted for 12 h. After cooling, the mixture was centrifuged, and the precipitate was washed with acetone and dried under vacuum at 50 °C for 10 h to obtain modified graphene oxide.

[0083] Modified graphene oxide and diethyl maleate were added to a reaction flask, stirred and preheated to 57°C, and 4,4'-diaminodicyclohexylmethane was slowly added dropwise. The addition was completed in 0.5 h, and the temperature was raised to 95°C and reacted for 12 h to obtain modified polyaspartic acid ester resin.

[0084] Preparation Example 4

[0085] Preparation of modified kaolin

[0086] Modified kaolin is prepared by the following method:

[0087] 30 kg of kaolin particles were calcined in a muffle furnace at 500 °C for 2 hours and then cooled. The kaolin particles and 6% (1.8 kg) of polymethylhydrosiloxane were weighed and mixed thoroughly. The mixture was then added to a ball mill jar, using steel balls as the milling medium: one Φ20 mm steel ball, six Φ10 mm steel balls, and twenty Φ6 mm steel balls. The main disc frequency was 50 Hz. The mixture was ball-milled for 30 minutes. The product was repeatedly washed with petroleum ether, centrifuged, and the lower precipitate was collected and vacuum-dried at 60 °C. The precipitate was then ground through a 200-mesh sieve to obtain modified kaolin.

[0088] Preparation Example 5

[0089] Preparation of modified kaolin

[0090] Modified kaolin is prepared by the following method:

[0091] 30 kg of kaolin particles were calcined in a muffle furnace at 600 °C for 2 hours and then cooled. The kaolin particles and 10% (3 kg) of polymethylhydrosiloxane were weighed and mixed thoroughly before being added to a ball mill jar. Steel balls were used as the milling medium, with one Φ20 mm steel ball, six Φ10 mm steel balls, and twenty Φ6 mm steel balls. The main disc frequency was 50 Hz. The mixture was ball-milled for 40 minutes. The product was repeatedly washed with petroleum ether, centrifuged, and the lower precipitate was collected and vacuum-dried at 75 °C. The precipitate was then ground through a 200-mesh sieve to obtain modified kaolin.

[0092] Example

[0093] Example 1

[0094] The water-based two-component waterproof coating for drinking water and water storage tanks consists of component A, component B, and water, wherein the weight ratio of component A, component B, and water is 1:2:0.6.

[0095] Component A includes the following raw materials:

[0096] 80kg of polyol, specifically 60kg of polyethylene glycol PEG1000 and 20kg of polyether polyol 330N;

[0097] 20 kg of diphenylmethane diisocyanate;

[0098] 1 kg of stabilizer, specifically tartaric acid;

[0099] Component B includes the following raw materials:

[0100] 25 kg of plasticizer, specifically 10 kg of dibutyl phthalate and 15 kg of chlorinated paraffin;

[0101] Chain extender 2.5 kg, specifically 2,2-dihydroxymethylbutyric acid;

[0102] The filler material is 55 kg, specifically 33 kg of light calcium carbonate and 22 kg of modified kaolin prepared in Example 4.

[0103] 9 kg of CO2 absorbent, specifically using ordinary silicate cement;

[0104] The catalyst is 0.1 kg, specifically bis(dimethylaminopropyl)isopropanolamine.

[0105] Waterproof coatings are prepared through the following steps:

[0106] Synthesis of Component A: Polyol is added to a reaction vessel, stirred and heated to 110°C, and vacuum dehydrated for 1 hour. After cooling to 60°C, diphenylmethane diisocyanate and stabilizer are added, and the mixture is heated to 85°C and reacted for 2 hours. After cooling, the product is discharged to obtain Component A. Synthesis of Component B: Plasticizer is added to a reactor, heated to 90°C, and filler, chain extender and CO2 absorbent are added. After heating to 110°C, vacuum dehydrated for 2 hours. After cooling to 50°C, catalyst is added, and vacuum degassing is performed for 0.5 hours. The product is discharged to obtain Component B.

[0107] Waterproof coating preparation: Mix component A, component B and water according to the weight ratio, stir evenly to obtain waterproof coating.

[0108] Example 2

[0109] The water-based two-component waterproof coating for drinking water and water storage tanks consists of component A, component B, and water, with a weight ratio of component A, component B, and water of 1:2.2:0.9.

[0110] Component A includes the following raw materials:

[0111] 100 kg of polyol, specifically 70 kg of polypropylene glycol PPG2000 and 30 kg of polyether polyol 330N;

[0112] 24 kg of diphenylmethane diisocyanate;

[0113] Stabilizer 2kg, specifically tartaric acid;

[0114] Component B includes the following raw materials:

[0115] 35 kg of plasticizer, specifically 20 kg of tributyl acetylacetonate and 15 kg of chlorinated paraffin;

[0116] Chain extender 3.2kg, specifically polyaspartic acid ester resin;

[0117] 70 kg of filler was used, specifically 45 kg of light calcium carbonate and 25 kg of modified kaolin prepared in Example 4.

[0118] 13 kg of CO2 absorbent, specifically calcium hydroxide;

[0119] 0.3 kg of catalyst, specifically triethylamine.

[0120] Waterproof coatings are prepared through the following steps:

[0121] Synthesis of Component A: Polyol is added to a reactor, stirred and heated to 120°C, and vacuum dehydrated for 2 hours. After cooling to 70°C, diphenylmethane diisocyanate and stabilizer are added, and the mixture is heated to 90°C and reacted for 3 hours. After cooling, the product is discharged to obtain Component A. Synthesis of Component B: Plasticizer is added to a reactor, heated to 100°C, and filler, chain extender and CO2 absorbent are added. After heating to 120°C, vacuum dehydrated for 2 hours. After cooling to 55°C, catalyst is added, and vacuum degassing is performed for 0.5 hours. The product is discharged to obtain Component B.

[0122] Waterproof coating preparation: Mix component A, component B and water according to the weight ratio, stir evenly to obtain waterproof coating.

[0123] Example 3

[0124] The water-based two-component waterproof coating for drinking water and water storage tanks consists of component A, component B, and water, wherein the weight ratio of component A, component B, and water is 1:2.1:0.7.

[0125] Component A includes the following raw materials:

[0126] 88 kg of polyols, specifically 44 kg of polyethylene glycol PEG1000 and 44 kg of polypropylene glycol PPG2000;

[0127] 21 kg of diphenylmethane diisocyanate;

[0128] Stabilizer 1.5kg, specifically salicylic acid;

[0129] Component B includes the following raw materials:

[0130] 30 kg of plasticizer, specifically 10 kg of dibutyl phthalate and 20 kg of tributyl acetyl citrate;

[0131] Chain extender 2.9 kg, specifically trimethylolpropane;

[0132] The filler material weighed 65 kg, specifically 39 kg of light calcium carbonate and 26 kg of modified kaolin prepared in Example 5.

[0133] 11 kg of CO2 absorbent, specifically using ordinary silicate cement;

[0134] The catalyst is 0.2 kg, specifically N-(dimethylaminopropyl)diisopropanolamine.

[0135] Waterproof coatings are prepared through the following steps:

[0136] Synthesis of Component A: Polyol was added to a reactor, stirred and heated to 115°C, and vacuum dehydrated for 1.5 h. After cooling to 65°C, diphenylmethane diisocyanate and stabilizer were added, and the mixture was heated to 88°C and reacted for 2.5 h. After cooling, the product was discharged to obtain Component A. Synthesis of Component B: Plasticizer was added to a reactor, and the mixture was heated to 96°C. Filler, chain extender and CO2 absorbent were added, and the mixture was heated to 115°C and vacuum dehydrated for 2 h. After cooling to 52°C, catalyst was added, and vacuum degassing was performed for 0.5 h. The product was discharged to obtain Component B.

[0137] Waterproof coating preparation: Mix component A, component B and water according to the weight ratio, stir evenly to obtain waterproof coating.

[0138] Example 4

[0139] The only difference between this embodiment and Embodiment 1 is the choice of chain extender in component B.

[0140] In this embodiment, the chain extender for component B is 1.66 kg of 2,2-dihydroxymethylbutyric acid and 0.84 kg of the modified polyaspartic acid ester resin prepared in Preparation Example 1.

[0141] The preparation method of the waterproof coating is the same as that in Example 1.

[0142] Example 5

[0143] The only difference between this embodiment and Embodiment 1 is the choice of chain extender in component B.

[0144] In this embodiment, the chain extender for component B is 1.48 kg of 2,2-dihydroxymethylbutyric acid and 1.02 kg of the modified polyaspartic acid ester resin prepared in Preparation Example 2.

[0145] The preparation method of the waterproof coating is the same as that in Example 1.

[0146] Example 6

[0147] The only difference between this embodiment and Embodiment 1 is the choice of chain extender in component B.

[0148] In this embodiment, the chain extender for component B is 1.5 kg of 2,2-dihydroxymethylbutyric acid and 1 kg of the modified polyaspartic acid ester resin prepared in Preparation Example 3.

[0149] The preparation method of the waterproof coating is the same as that in Example 1.

[0150] Comparative Example

[0151] Comparative Example 1

[0152] The only difference between this comparative example and Example 1 is that the filler in component B is different.

[0153] In this comparative example, the raw materials for component B were 33 kg of light calcium carbonate and 22 kg of kaolin, and the kaolin was unmodified.

[0154] Performance testing

[0155] The waterproof coatings prepared in Examples 1-6 and Comparative Example 1 were scraped onto a polytetrafluoroethylene plate to form a coating film with a thickness of 1.5 mm. After curing for 7 days under standard test conditions of 23°C and 50% relative humidity, samples were prepared.

[0156] Tensile properties: The tensile strength and elongation at break of the waterproof coating were tested according to the method in 9.2.1 of GB / T 16777-2008 "Test Methods for Waterproof Coatings for Buildings" without treatment. The tensile speed was 500 mm / min, and the results are recorded in Table 1.

[0157] Tear strength: The tear strength of the waterproof coating was tested according to the method of right-angle specimen in GB / T 529-2008 "Determination of tear strength of vulcanized rubber or thermoplastic rubber (trouser-shaped, right-angled and crescent-shaped specimens)". The tensile speed was 500 mm / min and the results were recorded in Table 1.

[0158] Impermeability: The water resistance of the waterproof coating was tested according to the method for impermeability in GB / T 16777-2008 "Test Methods for Waterproof Coatings for Buildings" (section 15). The metal mesh aperture was 0.5 mm, and the results are recorded in Table 1.

[0159] Volatile organic compounds (VOCs): The determination was carried out according to the method in section 5.1 of JC1066-2008 "Limits of Hazardous Substances in Building Waterproof Coatings" and the results are recorded in Table 1.

[0160] Table 1

[0161]

[0162]

[0163] Data Analysis:

[0164] As shown in Table 1, the waterproof coating prepared in this application exhibits excellent tensile properties and tear strength, as well as superior water resistance and durability, making it suitable for applications requiring long-term immersion in water. The waterproof coating prepared in this application has a low VOC content, and the limits for harmful substances comply with the "Regulations for Safety Evaluation of Drinking Water Transmission and Distribution Equipment and Protective Materials" standard. The waterproof coating poses no potential risk of leaching when in contact with water and can be used in drinking water reservoirs and water storage tanks.

[0165] According to Example 1 and Comparative Example 1, the kaolin in the filler of Comparative Example 1 was not modified, resulting in a decrease in the tensile properties and tear strength of the waterproof coating. This may be because the polymethylhydrosiloxane-modified kaolin exhibits better dispersibility in the polyurethane system. The polymethylhydrosiloxane promotes the bonding between the kaolin and polyurethane molecular chains, thus better leveraging the reinforcing effect of kaolin and improving mechanical properties. Furthermore, the addition of polymethylhydrosiloxane-modified kaolin to the waterproof coating further enhances its water resistance.

[0166] According to Examples 1 and 4-6, the chain extender is selected from a specific ratio of 2,2-dihydroxymethylbutyric acid and modified polyaspartic acid ester resin. The modified polyaspartic acid ester resin is grafted with graphene oxide. The reactive sites of graphene oxide optimize the molecular chain structure of polyurethane during chain extension, thereby making the waterproof coating more dense, uniform and consistent, and improving the mechanical properties and water resistance.

[0167] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A water-based two-component drinking water and reservoir waterproof coating characterized by: Consists of A component, B component and water, wherein the weight ratio of A component, B component and water is 1:(2-2.2):(0.6-0.9); The A component comprises the following raw materials by weight: Polyhydric alcohol 80-100 parts; Diphenyl methane diisocyanate 20-24 parts; Stabilizer 1-2 parts; The B component comprises the following raw materials by weight: Plasticizer 25-35 parts; Chain extender 2.5-3.2 parts, the chain extender is selected from a mixture of 2,2-dimethylol butyric acid and modified polyaspartic ester resin according to a weight ratio of 1:(0.5-0.7), Filler 55-70 parts, the filler is selected from a mixture of light calcium carbonate and modified kaolin, the weight ratio of the light calcium carbonate and the modified kaolin is (1.4-1.8):1; CO2 absorbent 9-13 parts; Catalyst 0.1-0.3 parts; The modified polyaspartic ester resin is composed of the following raw materials by weight: Graphene oxide 2-5 parts; Silane coupling agent KH-550 25-32 parts; Diethyl maleate 100-110 parts; 4,4'-diamino dicyclohexyl methane 68-75 parts; The modified kaolin is prepared by the following method: After the kaolin particles are calcined in a muffle furnace at 500-600 DEG C and cooled, the kaolin particles and 6%-10% of polymethylhydrogen siloxane by weight are weighed, mixed uniformly, and then added to a ball mill tank with steel balls as the ball milling medium for ball milling for 30-40 min. The product is repeatedly washed with petroleum ether, centrifuged, and the lower sediment is taken out and vacuum dried at 60-75 DEG C. After being ground through a 200 mesh sieve, the modified kaolin is obtained.

2. The water-based two-component drinking water and water reservoir waterproof coating according to claim 1, characterized in that, The modified polyaspartic ester resin is prepared by the following method: The graphene oxide is added to an ethanol aqueous solution, heated to 60-70 DEG C, and fully stirred to obtain a mixed solution. The silane coupling agent KH-550 is mixed with ethanol to obtain a KH-550 ethanol solution. The KH-550 ethanol solution is added to the mixed solution, heated to 75-80 DEG C for reaction, and then centrifuged after cooling. The precipitate is washed and dried to obtain modified graphene oxide. The modified graphene oxide and diethyl maleate are added to a reaction bottle, stirred and preheated to 55-60 DEG C, and then 4,4'-diamino dicyclohexyl methane is slowly added dropwise. The temperature is raised to 90-100 DEG C for reaction for 10-12 h to obtain the modified polyaspartic ester resin.

3. A water-based two-component drinking water and water reservoir waterproof coating according to claim 1, characterized by: The polyhydric alcohol is selected from one or more of polypropylene glycol PPG2000, polyethylene glycol PEG1000, polyether polyol 330N, and polypropylene glycol PPG4000.

4. A water-based two-component drinking water and water reservoir waterproof coating according to claim 1, characterized by: The plasticizer is selected from one or more of chlorinated paraffin, dibutyl phthalate, and acetyl tri-butyl citrate.

5. A water-based two-component drinking water and water reservoir waterproof coating according to claim 1, characterized by: The catalyst is selected from one or more of bis(dimethylaminopropyl) isopropanolamine, N-(dimethylaminopropyl) diisopropanolamine, and triethylamine.

6. The water-based two-component drinking water and water reservoir waterproof coating according to claim 1, characterized in that, The waterproof coating is prepared by the following steps: Synthesis of A component: The polyhydric alcohol is vacuum dehydrated, and then diphenyl methane diisocyanate and a stabilizer are added after the temperature is lowered to 60-70 DEG C. The temperature is raised to 85-90 DEG C for reaction for 2-3 h, and then the A component is discharged. B component synthesis: add plasticizer into the reactor, heat to 90-100℃, add filler, chain extender and CO2 absorbent, heat to 110-120℃, vacuum dehydration, cool to 50-55℃, add catalyst, vacuum defoaming, discharge to obtain B component; Waterproof coating preparation: mix A component, B component and water according to weight ratio, stir uniformly to obtain waterproof coating.

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