Water-based bi-component waterproof coating for drinking water and reservoir

Abstract

The invention discloses a water-based bi-component waterproof coating for drinking water and reservoirs, and relates to the field of waterproof coatings. The invention relates to a water-based double-component waterproof coating for drinking water and reservoirs. The water-based double-component waterproof coating comprises a component A, a component B and water, wherein the weight ratio of the component A to the component B to the water is 1: (2-2.2): (0.6-0.9); the component A is prepared from the following raw materials in parts by weight: 80 to 100 parts of polyhydric alcohol; 20 to 24 parts of diphenylmethane diisocyanate; 1-2 parts of a stabilizer; the component B comprises the following raw materials in parts by weight: 25-35 parts of a plasticizer; 2.5 to 3.2 parts of a chain extender; 55-70 parts of a filler; 9-13 parts of a CO2 absorbent; and 0.1-0.3 part of a catalyst. The polyurethane waterproof coating prepared in the invention is green and environment-friendly, has excellent water resistance and mechanical properties, and meets the requirements of drinking water pools, reservoirs and other projects with high environmental protection requirements.

Description

Technical Field

[0001] The invention relates to the field of waterproof coatings, and in particular to a water-based two-component waterproof coating for drinking water and water reservoirs. Background Art

[0002] Waterproof coatings are viscous liquid polymer materials that have no fixed shape at room temperature. After coating, they can form a tough waterproof film on the base surface after the volatilization of solvents and water or reaction curing. Waterproof coatings are made of synthetic polymers, polymers and asphalt, polymers and cement as the main film-forming substances, and are processed by adding various additives, modified materials, filling materials, etc. They are mainly used on the base surfaces of buildings such as roofs, basements, toilets, bathrooms and exterior walls.

[0003] Polyurethane waterproof coating is a commonly used waterproof coating with the characteristics of good extensibility, good adhesion, corrosion resistance, high tensile strength and easy construction. It is suitable for base construction with complex structure, especially for waterproofing and anti-seepage of roofs, basements and toilets.

[0004] However, for projects with high environmental protection requirements such as drinking water pools and reservoirs, ordinary polyurethane waterproof coatings cannot meet the needs. 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 will migrate into the water after long-term use, affecting water quality and causing harm to human health. Summary of the invention

[0005] In order to make the polyurethane waterproof coating meet the requirements of projects with high environmental protection such as drinking water pools and reservoirs, the present application provides a water-based two-component waterproof coating for drinking water and reservoirs.

[0006] The present application provides a water-based two-component waterproof coating for drinking water and water reservoirs using the following technical solutions: A water-based two-component waterproof coating for drinking water and water reservoirs, 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); The A component includes the following raw materials in parts by weight: Polyol 80-100 parts; 20-24 parts of diphenylmethane diisocyanate; 1-2 parts of stabilizer; The B component includes the following raw materials in parts by weight: 25-35 parts of plasticizer; Chain extender 2.5-3.2 parts; 55-70 parts of filler; CO 2 9-13 parts of absorbent; Catalyst 0.1-0.3 parts.

[0007] Through the above technical scheme, in the present application, water is used as a curing agent to replace MOCA to grow the polyurethane molecular chain to form a coating film, and no organic solvent is added to the raw materials. Diphenylmethane diisocyanate is used instead of the highly toxic toluene diisocyanate, and no dispersants or latent curing agents that may migrate harmful components are added to the raw materials. 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 reservoirs.

[0008] A prepolymer containing -NCO is formed by polyol and diphenylmethane diisocyanate, and -NCO reacts with water to form a polymer compound. The chain extender ensures the dispersion of water in the polyurethane system and improves the film-forming property; the plasticizer is used to improve the construction performance of the coating and increase the softness and elasticity of the coating; the filler is used to improve the physical and mechanical properties of the waterproof coating; CO 2 The absorbent is used to absorb the CO generated by the reaction of -NC0 and water. 2 Gas, reduce the phenomenon of bubbles or pinholes in the coating film. Through the synergy of raw material components, the coating film of the prepared waterproof coating has a smooth appearance, good coating uniformity and density, good construction performance, and excellent physical and mechanical properties.

[0009] Optionally, the chain extender is selected from one or more of 2,2-dihydroxymethylbutyric acid, trimethylolpropane, polyaspartic acid resin and modified polyaspartic acid resin.

[0010] Through the above technical solution, the chain extender contains a hydrophilic group, which can promote the compatibility of water and polyurethane prepolymer, promote the chain extension reaction of water and -NCO, generate a high molecular polymer, and improve the softness and extensibility of the polyurethane polymer.

[0011] Optionally, the chain extender is a mixture of 2,2-dihydroxymethylbutyric acid and modified polyaspartic acid resin in a weight ratio of 1:(0.5-0.7), and the modified polyaspartic acid resin is composed of the following raw materials in parts by weight: Graphene oxide 2-5 parts; Silane coupling agent KH-550 25-32 parts; 100-110 parts of diethyl maleate; 4,4'-diaminodicyclohexylmethane 68-75 parts.

[0012] Through the above technical scheme, 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 graphene oxide is introduced. Graphene oxide has a large number of reactive active points, thereby optimizing the structure of the polyurethane system during chain extension, making the molecular arrangement more orderly, and the coating film uniform and dense, thereby improving the water resistance, corrosion resistance and tensile properties of the coating film.

[0013] Optionally, the modified polyaspartic acid ester resin is prepared by the following method: Adding graphene oxide to an ethanol aqueous solution, heating to 60-70° C., and fully stirring to obtain a mixed solution, uniformly mixing a silane coupling agent KH-550 and ethanol to obtain a KH-550 ethanol solution, adding the KH-550 ethanol solution to the mixed solution, heating to 75-80° C. for reaction, cooling and centrifuging, washing and drying the precipitate, and obtaining modified graphene oxide; Add modified graphene oxide and diethyl maleate into a reaction bottle, preheat to 55-60°C with stirring, slowly drop 4,4'-diaminodicyclohexylmethane, raise the temperature to 90-100°C and react for 10-12h to obtain modified polyaspartic acid ester resin.

[0014] Through the above technical scheme, the graphene oxide is first modified using the silane coupling agent KH-550, and the silane reacts with the hydroxyl group of the graphene oxide after hydrolysis, and the amino group at the other end reacts with diethyl maleate, thereby achieving a firm combination of graphene oxide and polyaspartic acid ester resin, thereby achieving good dispersibility and compatibility.

[0015] Optionally, the filler is a mixture of light calcium carbonate and modified kaolin, and the weight ratio of the light calcium carbonate to the modified kaolin is (1.4-1.8):1.

[0016] Through the above technical solution, the filler plays a reinforcing role and prevents the volume of the coating from shrinking due to the volatilization of water. The light calcium carbonate and modified kaolin are selected for their good dispersibility in the polyurethane system, which makes the comprehensive performance of the coating better.

[0017] Optionally, the modified kaolin is prepared by the following method: The kaolin particles are calcined in a muffle furnace at 500-600°C and then cooled. The kaolin particles and 6%-10% of polymethylhydrogensiloxane by weight are weighed, mixed evenly and added into a ball mill. The mixture is ball milled for 30-40 minutes using steel balls as ball milling media. The product is repeatedly washed with petroleum ether, the lower precipitate is taken out after centrifugation, vacuum dried at 60-75°C, and ground through a 200-mesh sieve to obtain modified kaolin.

[0018] Through the above technical scheme, polymethyl hydrogen siloxane is used as a modified substance, and the modified kaolin is prepared by ball milling. The polymethyl hydrogen siloxane is coated on the surface of kaolin particles to improve the hydrophobicity of kaolin and the dispersibility in the polyurethane system. By adding modified kaolin to the waterproof coating, the water resistance and tensile properties of the coating are improved, and the durability of the coating is improved, which is suitable for long-term immersion in water.

[0019] Optionally, the polyol is selected from one or more of polypropylene glycol PPG2000, polyethylene glycol PEG1000, polyether polyol 330N, and polypropylene glycol PPG4000.

[0020] Through the above technical solution, multi-functional hydrophilic polyether polyols are selected to improve the uniformity of the coating film, thereby improving the performance of the coating film.

[0021] Optionally, the plasticizer is selected from one or more of chlorinated paraffin, dibutyl phthalate, and acetyl tributyl citrate.

[0022] Through the above technical solution, the above plasticizers are selected to meet the environmental protection requirements of waterproof coatings.

[0023] Optionally, the catalyst is selected from one or more of bis(dimethylaminopropyl)isopropanolamine, N-(dimethylaminopropyl)diisopropanolamine, and triethylamine.

[0024] Through the above technical solution, amine catalysts are selected to replace lead and tin catalysts, thereby avoiding the migration of lead and tin catalysts that may cause adverse effects on drinking water.

[0025] Optionally, the waterproof coating is prepared by the following steps: Synthesis of component A: vacuum dehydrate the polyol, cool it to 60-70°C, add diphenylmethane diisocyanate and stabilizer, heat it to 85-90°C, react for 2-3h, and obtain component A; Synthesis of component B: Add plasticizer into the reactor, raise the temperature to 90-100°C, add filler, chain extender and CO 2 The absorbent is heated to 110-120°C for vacuum dehydration, cooled to 50-55°C, the catalyst is added, vacuum degassing is performed, and the B component is obtained by discharging the material; Preparation of waterproof coating: Mix component A, component B and water according to a weight ratio, stir evenly, and obtain a waterproof coating.

[0026] Through the above technical scheme, the prepared waterproof coating has good water resistance and tensile properties, the coating film is uniform and corrosion-resistant, and is suitable for drinking water pools, reservoirs, and projects that are immersed in water for a long time.

[0027] In summary, the present application has at least one of the following beneficial effects: 1. In the present application, water is used as a curing agent instead of MOCA to grow the polyurethane molecular chain to form a coating film, and no organic solvent is added to the raw materials. Diphenylmethane diisocyanate is used instead of the highly toxic toluene diisocyanate, and no dispersants or latent curing agents that may migrate harmful components are added to the raw materials. The waterproof coating thus prepared is green and environmentally friendly and can be used in projects with high environmental requirements such as drinking water pools and reservoirs.

[0028] 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 graphene oxide is introduced. Graphene oxide has a large number of reactive sites, which optimizes the structure of the polyurethane system during chain extension, making the molecular arrangement more orderly and the coating film uniform and dense, thereby improving the water resistance, corrosion resistance and tensile properties of the coating film.

[0029] 3. Modified kaolin is prepared by ball milling with polymethyl hydrogen siloxane as a modified substance. Polymethyl hydrogen siloxane is coated on the surface of kaolin particles to improve the hydrophobicity of kaolin and its dispersibility in the polyurethane system. By adding modified kaolin to the waterproof coating, the water resistance and tensile properties of the coating are improved, and the durability of the coating is improved, which is suitable for long-term immersion in water. DETAILED DESCRIPTION

[0030] The present application is further described in detail below in conjunction with Examples 1-6 and Comparative Example 1.

[0031] Preparation Example Preparation Example 1 Preparation of modified polyaspartic acid ester resin Modified polyaspartic acid ester resin is composed of the following raw materials: Graphene oxide 0.2kg; Silane coupling agent KH-550 2.5kg; Diethyl maleate 10kg; 4,4'-Diaminodicyclohexylmethane 6.8kg.

[0032] The modified polyaspartic acid ester resin is prepared by the following method: Graphene oxide was added to 1.5 kg of ethanol aqueous solution, wherein the weight ratio of ethanol to water was 1:1, the temperature was raised to 60°C, and the mixture was fully stirred to obtain a mixed solution. The silane coupling agent KH-550 and 6 kg of ethanol were evenly mixed to obtain a KH-550 ethanol solution. The KH-550 ethanol solution was added to the mixed solution, the temperature was raised to 75°C, and the mixture was reacted for 12 hours. The mixture was cooled and centrifuged, and the precipitate was washed with acetone and vacuum dried at 50°C for 10 hours to obtain modified graphene oxide. Add modified graphene oxide and diethyl maleate into a reaction bottle, preheat to 55°C with stirring, slowly drop 4,4'-diaminodicyclohexylmethane, add the mixture over 0.5h, heat to 90°C and react for 10h to obtain modified polyaspartic acid resin.

[0033] Preparation Example 2 Preparation of modified polyaspartic acid ester resin Modified polyaspartic acid ester resin is composed of the following raw materials: Graphene oxide 0.5kg; Silane coupling agent KH-550 3.2kg; Diethyl maleate 11 kg; 4,4'-Diaminodicyclohexylmethane 7.5kg.

[0034] The modified polyaspartic acid ester resin is prepared by the following method: Graphene oxide was added to 3 kg of ethanol aqueous solution, wherein the weight ratio of ethanol to water was 1:1, the temperature was raised to 70°C, and the mixture was fully stirred to obtain a mixed solution. The silane coupling agent KH-550 and 8 kg of ethanol were evenly mixed to obtain a KH-550 ethanol solution. The KH-550 ethanol solution was added to the mixed solution, the temperature was raised to 80°C, and the mixture was reacted for 12 hours. The mixture was cooled and centrifuged, and the precipitate was washed with acetone and vacuum dried at 50°C for 10 hours to obtain modified graphene oxide. Add modified graphene oxide and diethyl maleate into a reaction bottle, preheat to 60°C with stirring, slowly drop 4,4'-diaminodicyclohexylmethane, complete the dropwise addition in 0.5 h, heat to 100°C and react for 12 h to obtain modified polyaspartic acid ester resin.

[0035] Preparation Example 3 Preparation of modified polyaspartic acid ester resin Modified polyaspartic acid ester resin is composed of the following raw materials: Graphene oxide 0.3kg; Silane coupling agent KH-550 2.8kg; Diethyl maleate 10.5 kg; 4,4'-Diaminodicyclohexylmethane 7.1kg.

[0036] The modified polyaspartic acid ester resin is prepared by the following method: Graphene oxide was added to 2.2 kg of ethanol aqueous solution, wherein the weight ratio of ethanol to water was 1:1, the temperature was raised to 65°C, and the mixture was fully stirred to obtain a mixed solution. The silane coupling agent KH-550 and 7 kg of ethanol were evenly mixed to obtain a KH-550 ethanol solution. The KH-550 ethanol solution was added to the mixed solution, the temperature was raised to 78°C, and the mixture was reacted for 12 hours. The mixture was cooled and centrifuged, and the precipitate was washed with acetone and vacuum dried at 50°C for 10 hours to obtain modified graphene oxide. Add modified graphene oxide and diethyl maleate into a reaction bottle, preheat to 57°C with stirring, slowly drop 4,4'-diaminodicyclohexylmethane, add the mixture over 0.5 h, heat to 95°C and react for 12 h to obtain modified polyaspartic acid resin.

[0037] Preparation Example 4 Preparation of modified kaolin Modified kaolin was prepared by the following method: 30kg of kaolin particles were placed in a muffle furnace at 500℃ for 2h and then cooled. The kaolin particles and 6% (1.8kg) of polymethylhydrogensiloxane were weighed and mixed evenly. The mixture was added into a ball mill. Steel balls were used as ball milling media. One Φ20mm steel ball, six Φ10mm steel balls, and 20 Φ6mm steel balls were prepared. The main plate frequency was 50Hz. The ball milling was performed for 30min. The product was repeatedly washed with petroleum ether. The lower precipitate was taken after centrifugation, dried under vacuum at 60℃, and ground through a 200-mesh sieve to obtain modified kaolin.

[0038] Preparation Example 5 Preparation of modified kaolin Modified kaolin is prepared by the following method: 30kg of kaolin particles were placed in a muffle furnace at 600℃ for 2h and then cooled. The kaolin particles and 10% (3kg) of polymethylhydrogensiloxane were weighed and mixed evenly. The mixture was added into a ball mill. Steel balls were used as ball milling media. One Φ20mm steel ball, six Φ10mm steel balls, and 20 Φ6mm steel balls were prepared. The main plate frequency was 50Hz. The ball milling was performed for 40min. The product was repeatedly washed with petroleum ether. The lower precipitate was taken after centrifugation, dried under vacuum at 75℃, and ground through a 200-mesh sieve to obtain modified kaolin. Example

[0039] Example 1 The water-based two-component waterproof coating for drinking water and reservoirs consists of component A, component B and water, wherein the weight ratio of component A, component B and water is 1:2:0.6.

[0040] Component A includes the following raw materials: 80kg of polyol, specifically 60kg of polyethylene glycol PEG1000 and 20kg of polyether polyol 330N; 20 kg of diphenylmethane diisocyanate; 1 kg of stabilizer, specifically tartaric acid; Component B includes the following raw materials: 25kg plasticizer, specifically 10kg dibutyl phthalate and 15kg chlorinated paraffin; 2.5 kg of chain extender, specifically 2,2-dimethylolbutyric acid; 55 kg of filler, specifically 33 kg of light calcium carbonate and 22 kg of modified kaolin prepared in Preparation Example 4; CO 2 9kg absorbent, specifically ordinary Portland cement; 0.1 kg of catalyst, specifically bis(dimethylaminopropyl)isopropanolamine.

[0041] The waterproof coating is prepared by the following steps: Synthesis of component A: put the polyol into the reactor, stir and heat it to 110℃, keep it warm for vacuum dehydration for 1h, cool it to 60℃, add diphenylmethane diisocyanate and stabilizer, heat it to 85℃ for reaction for 2h, cool it down and discharge it to obtain component A; Synthesis of component B: add the plasticizer into the reactor, heat it to 90℃, add filler, chain extender and CO 2 The absorbent was heated to 110°C for vacuum dehydration for 2 hours, cooled to 50°C, the catalyst was added, and vacuum degassing was performed for 0.5 hours to obtain component B; Preparation of waterproof coating: Mix component A, component B and water according to a weight ratio, stir evenly, and obtain a waterproof coating.

[0042] Example 2 The water-based two-component waterproof coating for drinking water and reservoirs consists of component A, component B and water, wherein the weight ratio of component A, component B and water is 1:2.2:0.9.

[0043] Component A includes the following raw materials: 100kg polyol, specifically 70kg polypropylene glycol PPG2000 and 30kg polyether polyol 330N; 24 kg of diphenylmethane diisocyanate; 2kg of stabilizer, specifically tartaric acid; Component B includes the following raw materials: 35kg of plasticizer, specifically 20kg of acetyl tributyl citrate and 15kg of chlorinated paraffin; 3.2 kg of chain extender, specifically polyaspartic acid ester resin; 70 kg of filler, specifically 45 kg of light calcium carbonate and 25 kg of modified kaolin prepared in Preparation Example 4; CO2 13kg of absorbent, specifically calcium hydroxide; 0.3 kg of catalyst, specifically triethylamine is selected.

[0044] The waterproof coating is prepared by the following steps: Synthesis of component A: put the polyol into the reactor, stir and heat it to 120℃, keep it warm for 2h, cool it to 70℃, add diphenylmethane diisocyanate and stabilizer, heat it to 90℃ for reaction for 3h, cool it down and discharge it to obtain component A; Synthesis of component B: add the plasticizer into the reactor, heat it to 100℃, add filler, chain extender and CO 2 The absorbent was heated to 120°C for vacuum dehydration for 2 hours, cooled to 55°C, the catalyst was added, and vacuum degassing was performed for 0.5 hours to obtain component B; Preparation of waterproof coating: Mix component A, component B and water according to a weight ratio, stir evenly, and obtain a waterproof coating.

[0045] Example 3 The water-based two-component waterproof coating for drinking water and reservoirs 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.

[0046] Component A includes the following raw materials: 88kg of polyol, specifically 44kg of polyethylene glycol PEG1000 and 44kg of polypropylene glycol PPG2000; 21 kg diphenylmethane diisocyanate; 1.5 kg of stabilizer, specifically salicylic acid; Component B includes the following raw materials: 30kg plasticizer, specifically 10kg dibutyl phthalate and 20kg acetyl tributyl citrate; 2.9 kg of chain extender, specifically trimethylolpropane; 65 kg of filler, specifically 39 kg of light calcium carbonate and 26 kg of modified kaolin prepared in Preparation Example 5; CO 2 11kg absorbent, specifically ordinary Portland cement; 0.2 kg of catalyst, specifically N-(dimethylaminopropyl)diisopropanolamine.

[0047] The waterproof coating is prepared by the following steps: Synthesis of component A: put the polyol into the reactor, stir and heat to 115℃, keep the temperature to vacuum dehydration for 1.5h, cool to 65℃, add diphenylmethane diisocyanate and stabilizer, heat to 88℃ to react for 2.5h, cool and discharge to obtain component A; Synthesis of component B: add the plasticizer into the reactor, heat to 96℃, add filler, chain extender and CO 2 The absorbent was heated to 115°C for vacuum dehydration for 2 hours, cooled to 52°C, the catalyst was added, and vacuum degassing was performed for 0.5 hours to obtain component B; Preparation of waterproof coating: Mix component A, component B and water according to a weight ratio, stir evenly, and obtain a waterproof coating.

[0048] Example 4 The difference between this embodiment and embodiment 1 is only that the chain extender in component B is different.

[0049] The chain extender of component B in this example is selected from 1.66 kg of 2,2-dihydroxymethylbutyric acid and 0.84 kg of the modified polyaspartic acid ester resin prepared in Preparation Example 1.

[0050] The preparation method of the waterproof coating is the same as that in Example 1.

[0051] Example 5 The difference between this embodiment and embodiment 1 is only that the chain extender in component B is different.

[0052] The chain extender of component B in this example is selected from 1.48 kg of 2,2-dihydroxymethylbutyric acid and 1.02 kg of the modified polyaspartic acid ester resin prepared in Preparation Example 2.

[0053] The preparation method of the waterproof coating is the same as that in Example 1.

[0054] Example 6 The difference between this embodiment and embodiment 1 is only that the chain extender in component B is different.

[0055] The chain extender of component B in this example is selected from 1.5 kg of 2,2-dihydroxymethylbutyric acid and 1 kg of the modified polyaspartic acid ester resin prepared in Preparation Example 3.

[0056] The preparation method of the waterproof coating is the same as that in Example 1.

[0057] Comparative Example Comparative Example 1 The difference between this comparative example and Example 1 is that the filler in component B is different.

[0058] In this comparative example, the raw materials of component B are 33 kg of light calcium carbonate and 22 kg of kaolin, and the kaolin is not modified.

[0059] Performance Testing 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 a relative humidity of 50%, a test sample was prepared.

[0060] Tensile properties: The tensile strength and elongation at break of the waterproof coating were tested according to the method of 9.2.1 Untreated tensile properties in GB / T 16777-2008 “Test methods for building waterproof coatings”. The tensile speed was 500 mm / min and the results are recorded in Table 1.

[0061] Tear strength: The tear strength of the waterproof coating is tested according to the method of right-angle specimens in GB / T 529-2008 "Determination of tear strength of vulcanized rubber or thermoplastic rubber (trouser-shaped, right-angled and crescent-shaped specimens)" with a tensile speed of 500 mm / min and recorded in Table 1.

[0062] Waterproofness: The water resistance of waterproof coatings was tested according to the water-proofness method in GB / T 16777-2008 Test methods for building waterproof coatings. The metal mesh aperture was 0.5 mm and was recorded in Table 1.

[0063] Volatile organic compounds (VOC): Determine according to the method of 5.1 Volatile organic compounds (VOC) in JC1066-2008 "Limits of Hazardous Substances in Building Waterproof Coatings" and record in Table 1.

[0064] Table 1 Data Analysis: According to Table 1, the waterproof coating prepared in this application has excellent tensile properties and tear strength, and also has excellent water resistance and durability, and is suitable for long-term immersion in water. The waterproof coating prepared in this application has a low VOC content, and the limit of harmful substances complies with the standards of the "Regulations on Safety Evaluation of Drinking Water Transmission and Distribution Equipment and Protective Materials". The waterproof coating has no potential precipitation risk when in contact with water, and can be used in drinking water pools and reservoirs.

[0065] According to Example 1 and Comparative Example 1, the kaolin in the filler of Comparative Example 1 was not modified, and the tensile properties and tear strength of the waterproof coating decreased. It may be that the kaolin modified with polymethyl hydrogen siloxane has better dispersibility in the polyurethane system, and the combination of kaolin and polyurethane molecular chains is promoted by polymethyl hydrogen siloxane, which is more conducive to the reinforcing effect of kaolin, thereby achieving the improvement of mechanical properties. At the same time, the water resistance of the waterproof coating is further improved by adding polymethyl hydrogen siloxane modified kaolin.

[0066] According to Example 1 and Examples 4-6, the chain extender is selected from 2,2-dihydroxymethylbutyric acid and modified polyaspartic acid resin in a specific ratio, and the modified polyaspartic acid resin is grafted with graphene oxide. The reactive active points of graphene oxide optimize the molecular chain structure of polyurethane during chain extension, so that the waterproof coating is denser, and the uniformity and consistency are improved, thereby improving the mechanical properties and water resistance.

[0067] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A water-based two-component waterproof coating for drinking water and reservoirs, characterized in that: It consists of 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); The A component includes the following raw materials in parts by weight: Polyol 80-100 parts; 20-24 parts of diphenylmethane diisocyanate; 1-2 parts of stabilizer; The B component includes the following raw materials in parts by weight: 25-35 parts of plasticizer; Chain extender 2.5-3.2 parts; 55-70 parts of filler; 9-13 parts of CO2 absorbent; Catalyst 0.1-0.3 parts.

2. The water-based two-component waterproof coating for drinking water and water reservoirs according to claim 1, characterized in that: The chain extender is selected from one or more of 2,2-dihydroxymethylbutyric acid, trimethylolpropane, polyaspartic acid resin and modified polyaspartic acid resin.

3. The water-based two-component waterproof coating for drinking water and water reservoirs according to claim 1, characterized in that: The chain extender is a mixture of 2,2-dihydroxymethylbutyric acid and modified polyaspartic acid resin in a weight ratio of 1:(0.5-0.7), and the modified polyaspartic acid resin is composed of the following raw materials in parts by weight: Graphene oxide 2-5 parts; Silane coupling agent KH-550 25-32 parts; 100-110 parts of diethyl maleate; 4,4'-diaminodicyclohexylmethane 68-75 parts.

4. The water-based two-component waterproof coating for drinking water and water reservoirs according to claim 3, characterized in that: The modified polyaspartic acid ester resin is prepared by the following method: Adding graphene oxide to an ethanol aqueous solution, heating to 60-70° C., and fully stirring to obtain a mixed solution, uniformly mixing a silane coupling agent KH-550 and ethanol to obtain a KH-550 ethanol solution, adding the KH-550 ethanol solution to the mixed solution, heating to 75-80° C. for reaction, cooling and centrifuging, washing and drying the precipitate, and obtaining modified graphene oxide; Add modified graphene oxide and diethyl maleate into a reaction bottle, preheat to 55-60°C with stirring, slowly drop 4,4'-diaminodicyclohexylmethane, raise the temperature to 90-100°C and react for 10-12h to obtain modified polyaspartic acid ester resin.

5. The water-based two-component waterproof coating for drinking water and water reservoirs according to claim 1, characterized in that: The filler is a mixture of light calcium carbonate and modified kaolin, and the weight ratio of the light calcium carbonate to the modified kaolin is (1.4-1.8):

1.

6. The water-based two-component waterproof coating for drinking water and water reservoirs according to claim 5, characterized in that: The modified kaolin is prepared by the following method: The kaolin particles are calcined in a muffle furnace at 500-600°C and then cooled. The kaolin particles and 6%-10% of polymethylhydrogensiloxane by weight are weighed, mixed evenly and added into a ball mill. Steel balls are used as ball milling media for 30-40 minutes. The product is repeatedly washed with petroleum ether, the lower precipitate is taken out after centrifugation, vacuum dried at 60-75°C, and ground through a 200-mesh sieve to obtain modified kaolin.

7. The water-based two-component waterproof coating for drinking water and water reservoirs according to claim 1, characterized in that: The polyol is selected from one or more of polypropylene glycol PPG2000, polyethylene glycol PEG1000, polyether polyol 330N, and polypropylene glycol PPG4000.

8. The water-based two-component waterproof coating for drinking water and water reservoirs according to claim 1, characterized in that: The plasticizer is selected from one or more of chlorinated paraffin, dibutyl phthalate, and acetyl tributyl citrate.

9. The water-based two-component waterproof coating for drinking water and water reservoirs according to claim 1, characterized in that: The catalyst is selected from one or more of bis(dimethylaminopropyl)isopropanolamine, N-(dimethylaminopropyl)diisopropanolamine and triethylamine.

10. The water-based two-component waterproof coating for drinking water and water reservoirs according to claim 1, characterized in that: The waterproof coating is prepared by the following steps: Synthesis of component A: vacuum dehydrate the polyol, cool it to 60-70°C, add diphenylmethane diisocyanate and stabilizer, heat it to 85-90°C, react for 2-3h, and obtain component A; Synthesis of component B: Add the plasticizer into the reactor, heat it to 90-100°C, add filler, chain extender and CO2 absorbent, heat it to 110-120°C for vacuum dehydration, cool it to 50-55°C, add the catalyst, vacuum degas, and discharge to obtain component B; Preparation of waterproof coating: Mix component A, component B and water according to a weight ratio, stir evenly, and obtain a waterproof coating.

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