A waterproof coating and a method for preparing the same

Abstract

This invention relates to the field of waterproof coatings, specifically to a waterproof coating and its preparation method; comprising: 40 to 70 parts of functionalized polymer emulsion, 10 to 30 parts of pigments and fillers, 1 to 3 parts of film-forming aid, 0.2 to 0.5 parts of defoamer, and 10 to 20 parts of water; as the core material, the above-mentioned functionalized polymer emulsion is prepared by in-situ soap-free emulsion copolymerization process using multiple polymer monomers, including a multifunctional fluorosilicone modified monomer; the multifunctional fluorosilicone modified monomer has a triazine ring structure framework, and 2-(perfluorohexyl)ethoxy, 2-(methacryloyloxy)ethoxy, and 3-(triethoxysilyl)propylamino are respectively attached to the three carbon atoms of this framework; this invention can significantly improve the adhesion of the coating to the substrate, while the triazine ring framework enhances the stability of the overall molecular structure, greatly improving the waterproof effect and weather resistance of the coating.

Description

Technical Field

[0001] This invention relates to the field of waterproof coatings, and more specifically to a waterproof coating and its preparation method. Background Technology

[0002] Waterborne polyurethane acrylate, as a high-performance polymer matrix, is widely used in waterproof coatings and other fields. This type of waterborne coating has good basic film-forming properties and is recognized as a good waterproof material. However, from the perspective of its inherent properties, it still has many shortcomings as a waterproof layer for long-term use. Traditional waterborne polymers are extremely easy to absorb water and swell, and due to the bottleneck of thermodynamic incompatibility, their crosslinking density is often insufficient, which makes it easy for water to penetrate.

[0003] To address the problems of traditional water-based waterproof coatings, modification is one of the most effective methods to compensate for polymer defects. Modification mainly involves two methods: physical blending and chemical structural modification. Physical modification typically involves direct blending and addition, a simple method, but small molecule additives are prone to migration and precipitation after film formation, leading to a decrease in the coating's mechanical strength. Chemical structural modification, on the other hand, introduces new multifunctional groups into the main chain through covalent bonding, altering the original molecular chain structure to construct a dense cross-linked network and a low surface energy interface. Currently, the commonly used core method for preparing such high-performance waterproof composite coatings is in-situ soap-free emulsion copolymerization. This method involves copolymerizing multifunctional fluorosilicone modified monomers with a triazine ring skeleton with acrylate monomers to form a dense cross-linked network structure, effectively inhibiting water molecule penetration. Summary of the Invention

[0004] The purpose of this invention is to provide a waterproof coating and its preparation method. Existing traditional water-based waterproof coatings suffer from significant shortcomings, including insufficient crosslinking density due to thermodynamic incompatibility, easy water absorption and swelling, and easy precipitation and loss of small-molecule additives during physical modification, leading to a decrease in mechanical strength. There is an urgent need to propose a water-based fluorosilicone multifunctional crosslinked polyurethane acrylate waterproof coating that can construct a dense crosslinked network and a low surface energy interface by introducing a multifunctional fluorosilicone modified monomer with a triazine ring skeleton, thereby blocking the water molecule penetration path and eliminating the risk of additive loss. Specifically, the technical solution of this invention includes the following steps:

[0005] Functionalized polymer emulsion 40-70 parts; pigments and fillers 10-30 parts; film-forming aid 1-3 parts; defoamer 0.2-0.5 parts; water 10-20 parts;

[0006] The functionalized polymer emulsion is prepared by in-situ soap-free emulsion copolymerization of polymer monomers, including multifunctional fluorosilicone modified monomers; the multifunctional fluorosilicone modified monomers have a triazine ring skeleton, and the three carbon atoms on the triazine ring skeleton are respectively connected to 2-(perfluorohexyl)ethoxy, 2-(methacryloyloxy)ethoxy and 3-(triethoxysilyl)propylamino.

[0007] Optionally, the polymer monomer further includes acrylate monomers; the functionalized polymer emulsion is prepared by in-situ soap-free emulsion copolymerization of a terminal double-bond aqueous polyurethane dispersion as the aqueous phase and the acrylate monomer and the multifunctional fluorosilicone modified monomer as the oil phase.

[0008] Optionally, the terminal double-bond aqueous polyurethane dispersion is prepared by reacting isophorone diisocyanate, polycarbonate diol, and dimethylolpropionic acid, followed by end-capping with hydroxyethyl methacrylate, neutralization, and dispersion with water.

[0009] Optionally, the acrylate monomers include butyl acrylate and methyl methacrylate.

[0010] Optionally, the pigments and fillers comprise a mixture of heavy calcium carbonate and talc;

[0011] The film-forming aid includes dipropylene glycol butyl ether.

[0012] A method for preparing a waterproof coating includes: thoroughly mixing anhydrous tetrahydrofuran with cyanuric chloride, cooling to 0-5°C, slowly adding a mixed solution of 2-(perfluorohexyl)ethanol and an acid-binding agent, and reacting for 1-3 hours to obtain a monosubstituted intermediate;

[0013] Hydroxyethyl methacrylate, a polymerization inhibitor, and an acid-binding agent were added to the reaction system containing the monosubstituted intermediate, and the mixture was heated to 40–50°C and reacted for 2–4 hours to obtain a disubstituted intermediate. Aminopropyltriethoxysilane and an acid-binding agent were then slowly added dropwise to the reaction system containing the disubstituted intermediate, and the mixture was heated to 80–90°C and reacted for 3–5 hours. After the reaction was completed, the system was cooled, and the precipitate was removed by vacuum filtration. The obtained filtrate was then evaporated under reduced pressure to remove the solvent, yielding a multifunctional fluorosilicone modified monomer.

[0014] A waterborne polyurethane dispersion with terminal double bonds was used as the aqueous phase. A sodium bicarbonate buffer system was added to adjust the pH of the solution to 7.0-7.5. An acrylate monomer and the multifunctional fluorosilicone modified monomer were mixed evenly to form the oil phase. The oil phase was slowly added dropwise to the aqueous phase. A water-soluble initiator was added, and the mixture was heated to 70-80°C to carry out in-situ soap-free emulsion copolymerization to obtain a functionalized polymer emulsion.

[0015] The functionalized polymer emulsion, pigments, fillers, film-forming aids, defoamers, and water are thoroughly mixed in a high-speed disperser to obtain the waterproof coating.

[0016] Optionally, the acid-binding agents all include triethylamine; the polymerization inhibitors include p-hydroxyanisole.

[0017] Optionally, the preparation process of the terminal double-bond waterborne polyurethane dispersion is as follows: isophorone diisocyanate, polycarbonate diol and dimethylolpropionic acid are thoroughly mixed and reacted, followed by the addition of hydroxyethyl methacrylate for end-capping reaction, and then neutralized and dispersed with water to obtain the terminal double-bond waterborne polyurethane dispersion.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The waterproof coating of the present invention uses a multifunctional fluorosilicone modified monomer containing a triazine ring skeleton; the monomer integrates perfluorohexyl, siloxane and polymerizable double bond; the perfluoro group gives the coating excellent hydrophobic properties, the siloxane group can significantly improve the adhesion of the coating to the substrate, and the triazine ring skeleton enhances the stability of the overall molecular structure. The three work synergistically to significantly improve the waterproof performance and weather resistance of the coating.

[0020] 2. The core functional polymer emulsion of this waterproof coating is prepared by in-situ soap-free emulsion copolymerization technology. This process avoids the use of traditional small molecule emulsifiers and eliminates the hidden danger of hydrophilic substances migrating and accumulating on the coating surface after film formation, thereby significantly improving the long-term water immersion resistance of the coating film.

[0021] 3. This scheme uses an end-double-bond waterborne polyurethane dispersion as the aqueous phase, and copolymerizes it with acrylate monomers and multifunctional fluorosilicone modified monomers. Through the participation of polyurethane end-double bonds in the polymerization reaction, a stable chemical bond is achieved between polyurethane, acrylate and fluorosilicone components, effectively combining the high elasticity and flexibility of polyurethane with the film-forming and weather-resistant properties of acrylate, thereby improving the overall mechanical strength of the coating.

[0022] 4. In the preparation of the end-double bond waterborne polyurethane dispersion, polycarbonate diol was specifically selected to participate in the reaction; the introduction of the polycarbonate skeleton can endow the polyurethane chain segments with better hydrolysis resistance, mechanical strength and anti-aging properties, thereby consolidating the durability foundation of the waterproof coating in complex climate and harsh environment.

[0023] 5. In the method for preparing multifunctional fluorosilicone modified monomers, a step-by-step temperature control strategy of cooling and multiple heating was adopted. Combined with the reaction characteristics of cyanuric chloride, this step-by-step addition and strict temperature control ensured that the substitution reaction of perfluorinated groups, polymerizable double bonds and siloxy groups had high selectivity and efficiency, effectively reduced side reactions, improved the synthesis purity and yield of key multifunctional monomers, and thus ensured the quality stability of the final coating product. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a bar chart showing the water absorption rate of the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] Example 1:

[0028] A waterproof coating, by weight, comprises the following components: 40 parts of functionalized polymer emulsion; 10 parts of pigments and fillers; 1 part of film-forming aid; 0.2 parts of defoamer; and 10 parts of water; wherein the functionalized polymer emulsion is prepared by in-situ soap-free emulsion copolymerization of polymeric monomers, including multifunctional fluorosilicone modified monomers.

[0029] The multifunctional fluorosilicone modified monomer has a triazine ring skeleton, with three carbon atoms on the triazine ring skeleton respectively attached to 2-(perfluorohexyl)ethoxy, 2-(methacryloyloxy)ethoxy and 3-(triethoxysilyl)propylamino; the polymerizable monomer also includes acrylate monomers.

[0030] The functionalized polymer emulsion is prepared by in-situ soap-free emulsion copolymerization of a terminal double-bond aqueous polyurethane dispersion as the aqueous phase and acrylate monomers and multifunctional fluorosilicone modified monomers as the oil phase. The terminal double-bond aqueous polyurethane dispersion is prepared by reacting isophorone diisocyanate, polycarbonate diol, and dimethylolpropionic acid, followed by end-capping with hydroxyethyl methacrylate, neutralization, and dispersion with water. The acrylate monomers include butyl acrylate and methyl methacrylate. The pigments and fillers include a mixture of heavy calcium carbonate and talc.

[0031] Film-forming aids include dipropylene glycol butyl ether; a method for preparing a waterproof coating includes thoroughly mixing anhydrous tetrahydrofuran and cyanuric chloride, cooling to 0°C, slowly adding a mixed solution of 2-(perfluorohexyl)ethanol and an acid-binding agent, and reacting for 1 hour to obtain a monosubstituted intermediate; adding hydroxyethyl methacrylate, a polymerization inhibitor, and an acid-binding agent to the reaction system containing the monosubstituted intermediate, and heating to 40°C to react for 2 hours to obtain a disubstituted intermediate;

[0032] Aminopropyltriethoxysilane and an acid-binding agent were slowly added dropwise to the reaction system containing the disubstituted intermediate. The temperature was raised to 80°C and the reaction was carried out for 3 hours. After the reaction was completed, the system was cooled, and the precipitate in the system was removed by vacuum filtration. The solvent in the obtained filtrate was removed by rotary evaporation under reduced pressure to obtain a multifunctional fluorosilicone modified monomer. The terminal double bond aqueous polyurethane dispersion was used as the aqueous phase. A sodium bicarbonate buffer system was added to adjust the pH of the solution to 7.0. The acrylate monomer and the multifunctional fluorosilicone modified monomer were mixed evenly to form the oil phase. The oil phase was slowly added dropwise to the aqueous phase. A water-soluble initiator was added, and the mixture was heated to a constant temperature of 75°C to carry out in-situ soap-free emulsion copolymerization to obtain a functionalized polymer emulsion.

[0033] Functionalized polymer emulsion, pigments, fillers, film-forming aids, defoamers, and water are thoroughly mixed and homogenized in a high-speed disperser to obtain a waterproof coating; the acid-binding agents all include triethylamine; the polymerization inhibitors include p-hydroxyanisole; the preparation process of the terminal double-bond waterborne polyurethane dispersion is as follows: isophorone diisocyanate, polycarbonate diol, and dimethylolpropionic acid are thoroughly mixed and reacted, followed by the addition of hydroxyethyl methacrylate for end-capping reaction, neutralization, and dispersion with water to obtain the terminal double-bond waterborne polyurethane dispersion;

[0034] In this embodiment, the low baseline amount of the functionalized polymer emulsion was set at 40 parts to test its effect on the ability to build crosslinked networks under low polymer matrix conditions. The introduction of multifunctional fluorosilicone modified monomers breaks through the thermodynamic incompatibility bottleneck of traditional physical blending. The 1,3,5-triazine ring skeleton, as a rigid aromatic heterocyclic hub, not only provides extremely high steric hindrance effect to shield the intrusion of free water molecules, but also achieves the following through the fine substitution on its three carbon atoms: 2-(perfluorohexyl)ethoxy (specifically, the structure is 2-(perfluorohexyl)ethoxy) imparts extremely low surface energy to the interface, 2-(methacryloyloxy)ethoxy provides active sites covalently anchored to the main chain, and 3-triethoxysilylpropylamino (specifically, the structure is 3-(triethoxysilyl)propylamino) undergoes hydrolytic condensation crosslinking in the later stage of film formation.

[0035] This molecular structure integrates three functional groups: hydrophobic, crosslinking, and anchoring, blocking the permeation pathway of water molecules. During the preparation process, the temperature of the first step nucleophilic substitution reaction is strictly controlled at 0°C and maintained for 1 hour. Utilizing the first-step reaction activity threshold of cyanuric chloride at low temperature, a hydrogen chloride molecule is precisely removed, effectively inhibiting the formation of multi-substituted byproducts. Subsequently, the second step reaction is carried out at 40°C. This thermodynamic condition perfectly matches the activation energy requirement of hydroxyethyl methacrylate. The polymerization inhibitor p-hydroxyanisole exhibits the best free radical capture efficiency at this temperature, thereby avoiding thermally initiated self-polymerization of the active double bond.

[0036] In a high-energy field of 80℃, aminopropyltriethoxysilane overcomes the steric hindrance and electronic effects caused by the increased electron cloud density of the 1,3,5-triazine ring due to the strong nucleophilicity of the primary amine group, and completes the third precise substitution. The in-situ copolymerization stage precisely anchors the pH of the system at 7.0. This neutral to slightly alkaline environment constitutes a key thermodynamic barrier to inhibit the hydrolysis kinetics of alkoxysilane, avoiding premature hydrolysis of silane groups leading to gelation in conventional aqueous emulsion polymerization, thereby achieving a synergistic hydrophobic and oleophobic antifouling effect.

[0037] The feed amounts for the synthesis of the multifunctional fluorosilicone modified monomer in this embodiment are as follows: 0.1 mol of cyanuric chloride dissolved in 150 mL of anhydrous tetrahydrofuran, 0.1 mol of 2-(perfluorohexyl)ethanol, 0.1 mol of hydroxyethyl methacrylate, and 0.1 mol of aminopropyltriethoxysilane; 0.1 mol of triethylamine (an acid-binding agent) and 0.05 g of p-hydroxyanisole (a polymerization inhibitor) were used in each of the three reaction steps; after the reaction, the multifunctional fluorosilicone modified monomer was obtained with a separation yield of 86.5% and an HPLC purity of 98.2%.

[0038] In the preparation of the terminal double bond waterborne polyurethane dispersion, the specific feeding conditions are as follows: 0.1 mol of polycarbonate diol, 0.3 mol of isophorone diisocyanate and 0.1 mol of dimethylolpropionic acid are reacted at 80℃ for 2 hours, then 0.2 mol of hydroxyethyl methacrylate is added and the reaction is capped at 80℃ for 2 hours. After cooling, 0.1 mol of triethylamine is used as a neutralizing agent for neutralization, and 300 g of deionized water is added for dispersion.

[0039] In the in-situ soap-free emulsion copolymerization stage, 200g of the above-mentioned end-double-bond waterborne polyurethane dispersion was used as the aqueous phase, and the oil phase consisted of 20g of butyl acrylate, 20g of methyl methacrylate and 10g of multifunctional fluorosilicone modified monomer. The water-soluble initiator used was 0.5g of potassium persulfate.

[0040] In this embodiment, 0.5g of potassium persulfate is used as the basic initiation system, which can provide a moderate free radical generation rate, ensure that the polymerization reaction starts smoothly at 75°C, avoid the risk of explosive polymerization or gelation caused by excessive initiator concentration, and at the same time ensure the basic conversion rate of monomer.

[0041] The sodium bicarbonate buffer system added in this embodiment is specifically prepared as follows: sodium bicarbonate is dissolved in deionized water to prepare a 0.1 mol / L aqueous solution, and the actual added volume is 50 mL, thereby precisely adjusting and maintaining the pH of the system at 7.0; the pigment and filler 10 parts are specifically composed of 6.7 parts heavy calcium carbonate and 3.3 parts talc, with a mass ratio of 2:1. This specific ratio can achieve the optimal gradation of coarse and fine particles, and has been fully verified to maximize the density and waterproof effect of the coating;

[0042] In the coating preparation process, the latex particles are thoroughly and evenly mixed under a high-speed disperser. The specific process parameters are set as follows: dispersion speed 1500 rpm and dispersion time 20 minutes. This specific combination of speed and time can ensure the full integration of latex particles and pigments and fillers, and avoid the film quality being affected by uneven dispersion or shear demulsification.

[0043] Example 2:

[0044] A waterproof coating, by weight, comprises the following components: 45 parts functionalized polymer emulsion; 15 parts pigments and fillers; 1.5 parts film-forming aid; 0.3 parts defoamer; and 12 parts water.

[0045] A method for preparing a waterproof coating includes: thoroughly mixing anhydrous tetrahydrofuran and cyanuric chloride, cooling to 2°C, slowly adding a mixed solution of 2-(perfluorohexyl)ethanol and an acid-binding agent, and reacting for 1.5 hours to obtain a monosubstituted intermediate; adding hydroxyethyl methacrylate, a polymerization inhibitor, and an acid-binding agent to the reaction system containing the monosubstituted intermediate, and heating to 45°C to react for 3 hours to obtain a disubstituted intermediate; and slowly adding aminopropyltriethoxysilane and an acid-binding agent to the reaction system containing the disubstituted intermediate, and heating to 85°C to react for 4 hours.

[0046] In this embodiment, the core formulation parameters and multi-step temperature-controlled reaction conditions were moderately adjusted; the temperature of the first step nucleophilic substitution reaction was increased to 2°C and the reaction time was extended to 1.5 hours to accelerate the nucleophilic attack rate of 2-(perfluorohexyl)ethanol, while relying on the steric hindrance effect to maintain the singleness of the substitution reaction; the second step reaction, which lasted for 3 hours at 45°C, gave hydroxyethyl methacrylate a more sufficient probability of molecular collision, ensuring the efficient grafting of active double bonds;

[0047] Reacting at 85℃ for 4 hours promotes the consumption of residual chlorine atoms by the primary amine group of aminopropyltriethoxysilane; as the amount of functionalized polymer emulsion increases to 45 parts, a more continuous hydrophobic phase is formed during the film formation process, and the dynamic process of spontaneous enrichment of fluorine segments to the air interface of the coating is enhanced, indicating that the process has good adaptability under the condition of raw material ratio and temperature fine adjustment.

[0048] In the fine-tuning process of this embodiment, the feeding parameters for the synthesis of the multifunctional fluorosilicone modified monomer were set as follows: 0.1 mol cyanuric chloride, 160 mL anhydrous tetrahydrofuran, 0.1 mol 2-(perfluorohexyl)ethanol, 0.1 mol hydroxyethyl methacrylate, and 0.1 mol aminopropyltriethoxysilane. In each of the three reaction steps, 0.1 mol of triethylamine was added as an acid-binding agent, and 0.06 g of p-hydroxyanisole was added as a polymerization inhibitor. Under these conditions, the separation yield of the multifunctional fluorosilicone modified monomer was 88.2%, and the HPLC purity was 98.5%.

[0049] In the emulsion copolymerization stage, 220g of terminal double-bond waterborne polyurethane dispersion was used as the aqueous phase, and the oil phase consisted of 25g of butyl acrylate, 20g of methyl methacrylate, and 12g of multifunctional fluorosilicone modified monomer. 0.6g of ammonium persulfate was used as the water-soluble initiator. Compared to Example 1, this example replaced the initiator with ammonium persulfate and slightly adjusted the amount to 0.6g to match the slightly higher total monomer content in the system and the adjusted reaction temperature. Ammonium persulfate has a higher decomposition rate at lower temperatures, which can quickly establish a free radical concentration in the early stage of polymerization, improve the initial conversion rate of the copolymerization reaction, thereby promoting the formation of a continuous hydrophobic phase and improving the hydrophobic properties after film formation.

[0050] In this embodiment, the sodium bicarbonate buffer system used is a 0.1 mol / L sodium bicarbonate aqueous solution, and the actual amount added is 60 mL to adjust the pH of the solution; the pigment and filler 15 parts are specifically composed of 10 parts heavy calcium carbonate and 5 parts talc; the thorough and uniform mixing in the coating preparation step is specifically achieved by dispersing at 1800 rpm for 25 minutes in a high-speed disperser, indicating that this dispersion process parameter range has a stable supporting effect on the fusion of latex particles and the dense film formation of the coating.

[0051] Example 3:

[0052] A waterproof coating, by weight, comprises the following components: 55 parts of functionalized polymer emulsion; 20 parts of pigments and fillers; 2 parts of film-forming aid; 0.4 parts of defoamer; 15 parts of water; the polymer monomers also include acrylate monomers; the functionalized polymer emulsion is prepared by in-situ soap-free emulsion copolymerization of a terminal double-bond aqueous polyurethane dispersion as the aqueous phase and acrylate monomers and multifunctional fluorosilicone modified monomers as the oil phase; the terminal double-bond aqueous polyurethane dispersion is prepared by reacting isophorone diisocyanate, polycarbonate diol, and dimethylolpropionic acid, followed by end-capping with hydroxyethyl methacrylate, neutralization, and dispersion with water;

[0053] This embodiment investigated the microphase separation behavior of in-situ soap-free emulsion copolymerization under moderate load. By increasing the amount of functionalized polymer emulsion to 55 parts, the terminal double-bond aqueous polyurethane dispersion was used as a macromolecular reactive emulsifier, which self-assembled in the aqueous phase to form a micelle template with thermodynamic stability. The alicyclic structure provided by isophorone diisocyanate and the hydrolysis-resistant skeleton of polycarbonate diol synergistically endowed the polyurethane prepolymer with excellent weather resistance. On this basis, the multifunctional fluorosilicone modified monomer spontaneously migrated to the hydrophobic core region inside the micelle due to the extreme hydrophobicity of the perfluorinated segments and was tightly wrapped by acrylate monomers.

[0054] This core-shell in-situ emulsion polymerization process not only avoids contact between alkoxysilanes and the aqueous phase, but also firmly locks the modified groups onto the polymer backbone through covalent bonding, eliminating the hidden danger of reduced coating mechanical strength caused by the precipitation of small molecule additives. In this example, the preparation parameters of the terminal double bond waterborne polyurethane dispersion are as follows: 0.1 mol of polycarbonate diol, 0.35 mol of isophorone diisocyanate and 0.12 mol of dimethylolpropionic acid are reacted at 85°C for 2.5 hours, followed by the addition of 0.26 mol of hydroxyethyl methacrylate for end-capping and reaction for 2.5 hours, neutralized by 0.12 mol of triethylamine and then dispersed in 350 g of deionized water.

[0055] The formulation for in-situ soap-free emulsion copolymerization is as follows: 250g of terminal double-bond aqueous polyurethane dispersion as the aqueous phase, and the oil phase is composed of 30g of butyl acrylate, 25g of methyl methacrylate and 15g of multifunctional fluorosilicone modified monomer. 0.8g of potassium persulfate is added as a water-soluble initiator to initiate the copolymerization reaction. In this embodiment, the amount of water-soluble initiator is increased to 0.8g to cope with the increase in monomer concentration under medium load system. The higher initiator concentration effectively improves the final conversion rate of the copolymerization reaction and ensures the compactness of the core-shell structure under high solids content.

[0056] Meanwhile, in this embodiment, the preparation process of the intermediate double bond waterborne polyurethane dispersion increases the reaction temperature from 80℃ to 85℃ and extends the reaction time from 2 hours to 2.5 hours. This parameter range promotes the deep reaction between isophorone diisocyanate and polycarbonate diol, increases the molecular weight and crosslinking network density of the polyurethane prepolymer, and gives the final coating higher mechanical strength and durable waterproof and seepage-proof performance.

[0057] Example 4:

[0058] A waterproof coating, by weight, comprises the following components: 65 parts of functionalized polymer emulsion; 25 parts of pigments and fillers; 2.5 parts of film-forming aid; 0.45 parts of defoamer; 18 parts of water; and a sodium bicarbonate buffer system is added to adjust the pH of the solution to 7.4.

[0059] This embodiment tested the buffer control mechanism and film formation kinetics at relatively high system concentrations; the pH of the system was precisely anchored at 7.4, and this slightly alkaline environment effectively inhibited the premature hydrolysis and condensation of alkoxysilanes; the sodium bicarbonate buffer system dynamically absorbed the trace amounts of acidic byproducts generated during polymerization during the reaction, maintaining the double layer thickness and zeta potential stability of the latex particle surface;

[0060] With the addition of 2.5 parts of the film-forming aid dipropylene glycol butyl ether, the spreading of the coating on the substrate surface and the fusion process of the latex particles are significantly optimized. As moisture evaporates, the released triethoxysilane groups are rapidly hydrolyzed under the trigger of air humidity, and undergo deep condensation with the hydroxyl groups on the substrate surface, forming a dense organic-inorganic interpenetrating network structure inside the coating film, which significantly improves dry and wet adhesion, and is especially suitable for dense and smooth substrates.

[0061] Example 5:

[0062] A waterproof coating, by weight, comprises the following components: 70 parts of functionalized polymer emulsion; 30 parts of pigments and fillers; 3 parts of film-forming aid; 0.5 parts of defoamer; and 20 parts of water. A method for preparing the waterproof coating includes: thoroughly mixing anhydrous tetrahydrofuran and cyanuric chloride, cooling to 5°C, slowly adding a mixed solution of 2-(perfluorohexyl)ethanol and an acid-binding agent, and reacting for 3 hours; heating to 50°C and reacting for 4 hours; and heating to 90°C and reacting for 5 hours.

[0063] This embodiment was tested under process parameters close to the design limit; the incorporation of perfluoroalkyl chains reached the maximum stoichiometric conversion rate within an initial reaction temperature of 5°C and an induction period of up to 3 hours.

[0064] Long-term heat treatment at 50℃ and 90℃ fully released the residual reactivity of the triazine ring skeleton, ensuring the grafting of the three functional groups; the physical stacking of 70 parts of high-concentration functionalized polymer emulsion and 30 parts of heavy calcium carbonate and talc mixture formed a highly dense organic-inorganic composite coating; the high electronegativity and low polarizability of fluorine atoms promoted the high enrichment of fluorine segments at the air interface of the coating, overcoming the inherent defect of water-based coatings absorbing water and swelling, and verifying the excellent robustness of this technical solution under high solids content formulations.

[0065] Comparative Example 1:

[0066] This comparative example provides a conventional waterborne polyurethane acrylate waterproof coating, which differs from Example 2 only in that: the polymer monomer does not contain a multifunctional fluorosilicone modified monomer, and the acrylate monomer is directly used as the oil phase for in-situ soap-free emulsion copolymerization. The remaining components and preparation process parameters are consistent with those of Example 2. This comparative example is used to compare the role of triazine cyclogroup multifunctional fluorosilicone modified monomer in the construction of crosslinking networks and the formation of hydrophobic interfaces.

[0067] Comparative Example 2:

[0068] This comparative example provides a physically blended modified waterproof coating, which differs from Example 2 only in that the polymer monomer does not contain a multifunctional fluorosilicone modified monomer. Instead, in the final coating formulation stage, a mixture of 2-(perfluorohexyl)ethanol and aminopropyltriethoxysilane monomers with the same fluorosilicone content is directly added to the system for physical blending. The remaining components and preparation process parameters are consistent with Example 2. This comparative example is used to compare the differences in effectiveness between in-situ covalent anchoring technology and traditional physical blending in solving the problem of additive migration and loss.

[0069] Comparative Example 3:

[0070] This comparative example provides a waterproof coating with a modified preparation process. The only difference between this example and Example 2 is that in the synthesis of the multifunctional fluorosilicone modified monomer, the first step nucleophilic substitution reaction was not controlled in the low-temperature range of 0-5°C. Instead, the first step reaction temperature was raised to 25°C and carried out at room temperature for 1.5 hours. The second step reaction temperature was 45°C, the third step reaction temperature was 85°C, and the remaining components and subsequent emulsion copolymerization process remained the same as in Example 2. This comparative example is used to illustrate that when the first step nucleophilic substitution temperature is not controlled in the low-temperature range, the high reactivity of cyanuric chloride may lead to the generation of multi-substituted byproducts, thereby affecting the precise incorporation of trifunctional groups and thus affecting the crosslinking density and waterproof effect of the coating.

[0071] Verification experiment:

[0072] To comprehensively evaluate the application performance of the waterborne fluorinated silicone multifunctional crosslinked polyurethane acrylate waterproof coating provided by the present invention, the coating samples prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to standardized tests, focusing on their surface hydrophobicity, water swelling resistance, interfacial adhesion and long-term weather resistance.

[0073] Testing standards:

[0074] This performance evaluation was conducted in strict accordance with the following national and industry standards: the water contact angle was measured according to GB / T30693-2014 Measurement of the water contact angle between plastic film and water; the water absorption rate test was conducted according to GB / T16777-2008 Test Method for Waterproof Coatings for Buildings, recording the mass change after immersion in water at room temperature for 168 hours; the adhesion test was conducted according to GB / T 9286-2021 Cross-cut test for paints and varnishes, and the rating was performed on a smooth ceramic tile substrate; the artificial climate aging test was conducted according to GB / T1865-2009 Artificial climate aging and artificial radiation exposure to filtered xenon arc radiation for paints and varnishes, with 1000 hours of UV irradiation and water spray cycle test.

[0075] Specific testing process:

[0076] Each group of coating samples was evenly applied to the surface of a standard cement board and a smooth ceramic tile. The samples were cured for 7 days at a standard ambient temperature of 23°C and a relative humidity of 50% until a complete film was formed. A contact angle meter was used to drop 5 microliters of deionized water onto the coating surface and the contact angle data after the droplet stabilized was recorded. The peeled free coating was then weighed and completely immersed in 25°C deionized water. After 168 hours, the coating was removed, the surface moisture was wiped off, and the coating was weighed again to calculate the water absorption rate.

[0077] A cross-cut test was performed on the coating on the tile surface to observe and grade the edge peeling. The sample was placed in a QUV accelerated aging test chamber and after 1000 hours of aging cycles, the surface water contact angle was remeasured, the contact angle retention rate was calculated, and the coating surface was visually observed for cracking or powdering.

[0078] Table 1 Performance test data of Examples 1-5 and Comparative Examples 1-3

[0079]

[0080] Experimental data show that the waterproof coatings prepared in Examples 1 to 5 of this invention exhibit significant technical advantages in all key indicators; compared with Comparative Example 1, which did not introduce multifunctional monomers, the water contact angle of the Example group increased to over 125°, and the water absorption rate decreased significantly to below 1.5%. Figure 1 As shown, this fully demonstrates the extremely low surface energy effect generated by the enrichment of perfluoroalkyl chains at the interface; compared with Comparative Example 2, which uses physical blending, the contact angle retention rate of the Example group remained stable at over 95% after 1000 hours of aging, and there was no cracking or powdering in appearance. This confirms that the hydrophobic groups are covalently anchored to the polymer backbone through active double bonds, effectively eliminating the surface migration and loss problems of small molecule additives.

[0081] Furthermore, Comparative Example 3, due to the lack of step temperature control, resulted in a surge of side reactions during monomer synthesis, and the functional groups could not be accurately grafted. Its adhesion and water resistance both showed significant degradation, which proves the robustness of the temperature-controlled multi-step synthesis process of this application in constructing a dense inorganic phase crosslinking network and providing excellent interfacial bonding.

[0082] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A water repellent coating, characterized by, By weight, it comprises the following components: 40-70 parts of functionalized polymer emulsion; 10-30 parts of pigments and fillers; 1-3 parts of film-forming aid; 0.2-0.5 parts of defoamer; and 10-20 parts of water. The functionalized polymer emulsion is prepared by in-situ soap-free emulsion copolymerization of polymer monomers, including multifunctional fluorosilicone modified monomers; the multifunctional fluorosilicone modified monomers have a triazine ring skeleton, and the three carbon atoms on the triazine ring skeleton are respectively connected to 2-(perfluorohexyl)ethoxy, 2-(methacryloyloxy)ethoxy and 3-(triethoxysilyl)propylamino. The polymer monomers also include acrylate monomers; the functionalized polymer emulsion is prepared by in-situ soap-free emulsion copolymerization of a terminal double-bond aqueous polyurethane dispersion as the aqueous phase and the acrylate monomers and the multifunctional fluorosilicone modified monomers as the oil phase. The acrylate monomers include butyl acrylate and methyl methacrylate.

2. A water repellent coating as claimed in claim 1, characterised in that: The terminal double bond waterborne polyurethane dispersion is prepared by reacting isophorone diisocyanate, polycarbonate diol, and dimethylolpropionic acid, followed by end capping with hydroxyethyl methacrylate, neutralization, and dispersion with water.

3. The waterproof coating as described in claim 1, characterized in that: The pigments and fillers include a mixture of heavy calcium carbonate and talc; The film-forming aid includes dipropylene glycol butyl ether.

4. A method for preparing a waterproof coating as described in any one of claims 1 to 3, characterized in that: The process includes thoroughly mixing anhydrous tetrahydrofuran with cyanuric chloride, cooling to 0–5°C, and slowly adding a mixed solution of 2-(perfluorohexyl)ethanol and an acid-binding agent for 1–3 hours to obtain a monosubstituted intermediate. Hydroxyethyl methacrylate, a polymerization inhibitor, and an acid-binding agent were added to the reaction system containing the monosubstituted intermediate, and the mixture was heated to 40–50°C and reacted for 2–4 hours to obtain a disubstituted intermediate. Aminopropyltriethoxysilane and an acid-binding agent were then slowly added dropwise to the reaction system containing the disubstituted intermediate, and the mixture was heated to 80–90°C and reacted for 3–5 hours. After the reaction was completed, the system was cooled, and the precipitate was removed by vacuum filtration. The obtained filtrate was then evaporated under reduced pressure to remove the solvent, yielding a multifunctional fluorosilicone modified monomer. A waterborne polyurethane dispersion with terminal double bonds was used as the aqueous phase. A sodium bicarbonate buffer system was added to adjust the pH of the solution to 7.0-7.

5. An acrylate monomer and the multifunctional fluorosilicone modified monomer were mixed evenly to form the oil phase. The oil phase was slowly added dropwise to the aqueous phase. A water-soluble initiator was added, and the mixture was heated to 70-80°C to carry out in-situ soap-free emulsion copolymerization to obtain a functionalized polymer emulsion. The functionalized polymer emulsion, pigments, fillers, film-forming aids, defoamers, and water are thoroughly mixed in a high-speed disperser to obtain the waterproof coating.

5. The method for preparing a waterproof coating as described in claim 4, characterized in that: The acid-binding agents all include triethylamine; the polymerization inhibitors include p-hydroxyanisole.

6. The method for preparing a waterproof coating as described in claim 4, characterized in that: The preparation process of the terminal double bond waterborne polyurethane dispersion is as follows: isophorone diisocyanate, polycarbonate diol and dimethylolpropionic acid are thoroughly mixed and reacted, then hydroxyethyl methacrylate is added for end-capping reaction, and after neutralization and water dispersion, the terminal double bond waterborne polyurethane dispersion is obtained.

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