Corrosion-resistant polymer composite waterproof coating and preparation method thereof

Abstract

The application discloses a kind of corrosion-resistant polymer composite waterproof coating and preparation method thereof, it is related to paint technical field.The corrosion-resistant polymer composite waterproof coating includes the following weight parts raw materials: 40-60 parts styrene-diene-styrene block copolymer, 25-35 parts epoxy resin E-51, 8-15 parts modified nanosilica, 15-25 parts modified polypropylene glycol, 8-12 parts toluene diisocyanate, 5-10 parts zinc phosphate, 10-18 parts dioctyl phthalate, 3-8 parts fumed white carbon black, 1-3 parts sodium benzoate, 3-6 parts dimethylol propionic acid, 1-4 parts triethanolamine, 2-4 parts triethylamine, 20-35 parts polyamide 650, 3-8 parts phenyl glycidyl ether, 40-60 parts deionized water.The waterproof coating raw material ratio of the application is scientific, modified nanosilica and polypropylene glycol improve compatibility and corrosion resistance;Preparation process is controllable, precision temperature control and dispersion guarantee stability;With high tensile strength and excellent salt fog resistance, chemical medium resistance, good construction operability, storage stability, wide application scenarios.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a corrosion-resistant polymer composite waterproof coating and its preparation method. Background Technology

[0002] In the field of coating technology, waterproof coatings, as key materials for protecting substrates from water and corrosive media, are widely used in construction, chemical, and transportation industries. However, existing waterproof coatings generally have performance shortcomings, making it difficult to simultaneously meet the requirements of corrosion resistance, mechanical strength, and construction stability.

[0003] Traditional single-resin waterproof coatings, such as pure epoxy waterproof coatings, have good rigidity and corrosion resistance, but poor flexibility and are prone to cracking; polyurethane waterproof coatings have excellent flexibility, but have insufficient weather resistance and are prone to swelling after long-term immersion; styrene-butadiene-styrene block copolymer (SBS) modified bitumen waterproof coatings are low in cost, but are prone to flowing at high temperatures and brittleness at low temperatures, and have weak resistance to chemical media, which cannot meet the long-term protection needs of harsh scenarios such as chemical equipment and marine engineering.

[0004] To improve performance, the industry often adopts the organic-inorganic composite modification approach, but there are still many bottlenecks in the existing technology: On the one hand, nano-inorganic fillers such as nano-silica have poor compatibility with organic resin systems, and direct addition is prone to agglomeration, which leads to defects in the coating and reduces corrosion resistance; on the other hand, the modification process of polymer raw materials such as polyether polyols mostly relies on destructive chain breaking or inefficient grafting, which can easily cause functional disorder, causing the molecular weight of crosslinked systems such as polyurethane to run out of control, affecting the stability of the emulsion and the mechanical properties of the coating.

[0005] Meanwhile, existing preparation processes suffer from problems such as inaccurate control of the reaction temperature between the curing agent and resin, easy oil-water separation during multiphase mixing, and incomplete solvent removal. These issues further lead to short shelf life of waterproof coatings, easy sagging or pinholes during construction, and ultimately, the salt spray and acid / alkali resistance of the final coating film is difficult to meet standards. Therefore, developing a corrosion-resistant polymer composite waterproof coating with scientifically formulated raw materials, controllable modification processes, and excellent comprehensive performance is key to solving the current technical challenges. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a corrosion-resistant polymer composite waterproof coating and its preparation method, solving the problem that traditional waterproof coatings struggle to balance corrosion resistance, mechanical strength, and construction stability.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A corrosion-resistant polymer composite waterproof coating comprises the following raw materials in parts by weight: 40-60 parts styrene-butadiene-styrene block copolymer, 25-35 parts epoxy resin E-51, 8-15 parts modified nano silica, 15-25 parts modified polypropylene glycol, 8-12 parts toluene diisocyanate, 5-10 parts zinc phosphate, 10-18 parts dioctyl phthalate, 3-8 parts fumed silica, 1-3 parts sodium benzoate, 3-6 parts dimethylolpropionic acid, 1-4 parts triethanolamine, 2-4 parts triethylamine, 20-35 parts polyamide 650, 3-8 parts phenyl glycidyl ether, and 40-60 parts deionized water.

[0009] Furthermore, the fumed silica is a hydrophilic fumed silica with a specific surface area of ​​200-300 m². 2 / g, can fully adsorb moisture and small molecules in the system, play a thickening and anti-settling role, and avoid coating stratification during storage; the purity of sodium benzoate is ≥99%, which enhances the corrosion resistance of the coating film, and its weight ratio with fumed silica is (1-3):(3-8), which can balance the thickening effect and corrosion resistance, ensuring that the coating has stable performance during storage and use, without agglomeration or protection failure.

[0010] Furthermore, the modified nano-silica is prepared using the following specific steps:

[0011] A1. Add nano-silica to a reaction vessel, then add deionized water, stir at 300-400 rpm while ultrasonically dispersing for 25-35 min to form a suspension; then add 50-60 mL of 0.5 mol / L nitric acid dropwise, raise the temperature to 60-70℃, and stir at 500 rpm for 2 h to complete hydroxyl activation; after the reaction is complete, filter the product and wash it with deionized water until neutral, then vacuum dry at 75-85℃ for 3-4 h to obtain hydroxyl-activated nano-silica;

[0012] A1, through the synergistic effect of stirring at 300-400 r / min and ultrasonic dispersion for 25-35 min, generates mechanical shear force and ultrasonic cavitation effect, which together break up the agglomeration of nano-silica, allowing it to be uniformly dispersed in deionized water; after adding 0.5 mol / L nitric acid, H... + Protonation generates silanol groups from surface silicon-oxygen anions, while simultaneously dissolving surface metal ion impurities. This process is accelerated by maintaining a constant temperature of 60-70℃ for 2 hours and thinning the adsorbed water layer. After filtration and washing until neutral, the product is vacuum dried at 75-85℃ to obtain activated nano-silica with high surface hydroxyl density, providing sufficient reaction sites for subsequent silane coupling.

[0013] A2. Add anhydrous ethanol and silane coupling agent KH-550 to the hydroxyl-activated nano silica prepared in A1, heat to 70℃, and stir at 600r / min for 4-5h. After the reaction is complete, filter the product and dry it under vacuum at 75-85℃ for 3-4h to obtain amino-modified nano silica.

[0014] A2 uses anhydrous ethanol as a co-solvent to allow the silane coupling agent KH-550 to undergo pre-hydrolysis with water to generate silanol. Subsequently, the silanol undergoes dehydration condensation with the hydroxyl groups on the surface of activated nano-silica to form ≡Si-O-Si≡ covalent bridges. The condensation reaction is promoted to proceed uniformly at 70℃ and 600r / min, ultimately fixing the amino group on the particle surface in a covalent manner, realizing the interfacial transition from inorganic to organic and improving compatibility with resin.

[0015] A3. Toluene and epichlorohydrin were added to the amino-modified nano-silica prepared in A2. The mixture was heated to 80°C and stirred at a constant temperature of 700 r / min for 5-6 h. Then, titanate coupling agent NDZ-101 was added, and stirring was continued at 700 r / min for 1 h. After the reaction was completed, toluene was removed by vacuum distillation at -0.09 MPa and 60-70°C for 1.5-2.5 h, so that the viscosity at 25°C was 1800-2500 mPa·s, thus obtaining modified nano-silica.

[0016] In toluene medium, the primary amine on the surface of amino-modified nano-silica undergoes a ring-opening reaction with the epoxy groups of epichlorohydrin to generate a β-hydroxy tertiary amine structure, allowing epichlorohydrin to be covalently grafted onto the particle surface. After adding titanate coupling agent NDZ-101, its Ti(OR)4 reacts with newly formed hydroxyl groups and surface silanol groups to form Ti-O-Si bridges, further shielding the hydrophilic hydroxyl groups and leaving long organic chains. After removing toluene by vacuum distillation at 60-70℃, modified nano-silica with a hydrophobic surface and chemical anchoring effect with the coating matrix is ​​obtained. The viscosity at 25℃ is 1800-2500 mPa·s, reflecting the network strength of the concentrated suspension, which is within the normal and controllable range.

[0017] Furthermore, the ratio of nano-silica to deionized water in A1 is 100g:150-200mL.

[0018] Furthermore, the ratio of anhydrous ethanol to silane coupling agent KH-550 in A2 is 100mL:8-12g.

[0019] Furthermore, the ratio of toluene, epichlorohydrin, and titanate coupling agent NDZ-101 in A3 is 100mL: 10-15g: 2-5g.

[0020] Furthermore, the modified polypropylene glycol is prepared using the following specific steps:

[0021] B1. Add polypropylene glycol to the reaction vessel, heat to 80°C, add toluene diisocyanate and dibutyltin dilaurate, and stir at 600 r / min for 2 h. Monitor by gel permeation chromatography to ensure that the number average molecular weight is maintained at 1800-2000 and the distribution is ≤1.2. Stop the reaction to obtain end-group activated polypropylene glycol.

[0022] In step B1, polypropylene glycol is heated to 80°C to enhance chain segment movement. Toluene diisocyanate and terminal hydroxyl groups undergo an addition reaction under the coordination catalysis of dibutyltin dilaurate to generate a polyurethane prepolymer with isocyanates at both ends. Stirring at 600 r / min ensures uniform dispersion of TDI. Online GPC monitoring maintains the number average molecular weight at 1800-2000 and the distribution ≤1.2 to prevent secondary chain extension, resulting in a structurally uniform, end-group activated polypropylene glycol that can be subsequently free radical block-modified.

[0023] B2. Add the end-group activated polypropylene glycol prepared in B1 to toluene, heat to 80℃, and stir at 500-600 r / min until completely dissolved; add N-phenylmaleimide and benzoyl peroxide, purge with nitrogen for protection, heat to 90℃, and stir at 700-800 r / min for 3 h; after the reaction is complete, remove toluene by vacuum distillation at -0.09 MPa and 90℃ for 1.5-2 h to obtain block copolymer polypropylene glycol;

[0024] B2 uses toluene as a solvent to completely dissolve end-group activated polypropylene glycol at 80℃ and 500-600 r / min. Benzoyl peroxide decomposes at 90℃ to generate benzoyloxy free radicals, which abstract α-H bonds of urethane to generate macromolecular free radicals. These free radicals undergo strict alternating copolymerization with N-phenylmaleimide to form short-chain hard segments and graft back onto the polypropylene glycol backbone. Nitrogen protection prevents oxygen from inhibiting polymerization, and after removing toluene by vacuum distillation, a "hard-soft" block structure is obtained, which endows the material with heat resistance, UV resistance, and antioxidant aging resistance.

[0025] B3. Add the block copolymer polypropylene glycol prepared in B2 to toluene, heat to 80℃, and stir at 500 r / min until dissolved; add trifluoroethanol dropwise, and stir at 800 r / min at 80℃ for 4 h; after completion, add deionized water, stir and wash 2-3 times at 400-500 r / min, and separate the organic phase after standing and layering; remove toluene from the organic phase by vacuum distillation at -0.08 MPa and 70℃ for 1-1.5 h, and vacuum dry at 80-90℃ for 5-7 h to obtain modified polypropylene glycol.

[0026] In a toluene solution, trifluoroethanol was added dropwise at 80°C to induce a nucleophilic addition reaction between the isocyanate groups (-NCO) at the ends of the block copolymer polypropylene glycol and trifluoroethanol, introducing the -CF3 group into the molecular chain end via an urethane bond. After the reaction was complete, trace impurities were removed by washing with water, toluene was removed by vacuum distillation, and the product was dried under vacuum to obtain fluorinated modified polypropylene glycol, which significantly reduced surface energy and improved hydrophobicity and compatibility with polyurethane systems.

[0027] Furthermore, the ratio of polypropylene glycol, toluene diisocyanate, and dibutyltin dilaurate in B1 is 100g:3-5g:0.1g.

[0028] Furthermore, the ratio of toluene, N-phenylmaleimide, and benzoyl peroxide in B2 is 80 mL: 8-10 g: 0.5-1 g.

[0029] Furthermore, the ratio of toluene to trifluoroethanol in B3 is 50 mL: 5-8 g.

[0030] A method for preparing a corrosion-resistant polymer composite waterproof coating specifically includes the following steps:

[0031] S1. Add styrene-butadiene-styrene block copolymer and dioctyl phthalate to a high-speed mixer and stir at 80-90℃ and 800-1000r / min for 30-40min until the styrene-butadiene-styrene block copolymer is completely swollen; then add fumed silica and sodium benzoate and continue stirring at 1000-1200r / min for 20-30min to form a uniform premix A.

[0032] S2. Add epoxy resin E-51 to the reactor, heat to 60-70℃, slowly add modified nano silica, stir at high speed of 1500-2000r / min for 40-50min, and simultaneously ultrasonically disperse for 20-30min to ensure uniform dispersion of modified nano silica and avoid agglomeration that could lead to coating defects, thus obtaining matrix B.

[0033] S3. Add modified polypropylene glycol, toluene diisocyanate, and dimethylolpropionic acid to a reaction vessel, heat to 80-90℃, then add triethanolamine, stir at 700-800 r / min for 2-3 h, and stop when the isocyanate group content reaches 8-10% by chemical titration; cool to 40-50℃, add triethylamine, stir at 500-600 r / min for 15-20 min; then slowly add deionized water under high-speed shear at 2500-3000 r / min, emulsify for 30-40 min, to obtain waterborne polyurethane dispersion C; control the temperature and stirring stepwise to precisely control the degree of isocyanate reaction, and form a stable waterborne polyurethane dispersion through high-speed shear emulsification;

[0034] S4. Slowly add premix A to matrix B, stir at 70-80℃ and 1200-1500 r / min for 60-80 min, then cool to 55℃, add waterborne polyurethane dispersion C and polyamide 650 in sequence, stir at 1000-1200 r / min for 40-50 min, finally add zinc phosphate, continue stirring at 800-1000 r / min for 30-40 min; maintain 55℃, reduce the speed to 500-800 r / min, and continue stirring for 2-3 h; slowly add phenyl glycidyl ether, stir at 600-700 r / min for 20-30 min, and adjust the viscosity to 5000-8000 mPa·s;

[0035] S5. Stop heating, cool to room temperature, filter with a 100-120 mesh filter to remove impurities and undispersed particles, dispense into sealed containers, and store away from light to obtain corrosion-resistant polymer composite waterproof coating.

[0036] Furthermore, the ultrasonic dispersion power in S2 is 400W, and the ultrasonic process employs an intermittent ultrasonic method of 5 minutes of ultrasonication followed by 2 minutes of rest. This method can break up the modified nano-silica aggregates through high-frequency vibration, ensuring uniform dispersion, while avoiding excessive heat generated by continuous ultrasonication, which could lead to an abnormal increase in system temperature and affect the bonding stability between epoxy resin and nanoparticles.

[0037] Furthermore, the filtered coating in step S5 needs to be left to stand for 2 hours at 25°C and 40% relative humidity to allow the microbubbles in the system to escape naturally before being packaged. This provides sufficient time for the microbubbles in the coating system to escape, preventing residual bubbles from causing defects such as pinholes and blistering after the coating film dries. At the same time, these environmental parameters prevent the coating from absorbing moisture or losing water during the standing process, ensuring stable viscosity and consistent product performance after subsequent packaging.

[0038] This invention provides a corrosion-resistant polymer composite waterproof coating and its preparation method, which has the following beneficial effects:

[0039] 1. This invention's waterproof coating utilizes organic-inorganic synergistic modification to construct a multi-layered protective system of "dense barrier + hydrophobic protection + passivation and rust prevention." Modified nano-silica forms a stable covalent bond with the resin, significantly increasing the coating's density and effectively blocking the penetration of corrosive media such as water, salt spray, and acids and alkalis. The fluorine-containing groups introduced by modified polypropylene glycol enhance surface hydrophobicity, reducing moisture adhesion and intrusion. Zinc phosphate reacts with the substrate to form a passivation protective film, delaying rust formation. Simultaneously, the synergistic effect of SBS and polyurethane balances the rigidity and flexibility of the coating, avoiding the defects of traditional coatings such as easy cracking and swelling. It can meet the needs of conventional waterproofing scenarios such as building roofs and basements, and is also suitable for harsh environments such as chemical equipment and marine engineering where long-term contact with corrosive media is required, solving the problems of insufficient protective capacity and limited application scenarios of single coatings.

[0040] 2. This waterproof coating system exhibits excellent stability. Optimized raw material formulation and modification processes ensure uniform dispersion of all components, with no significant particle agglomeration or phase separation. Even after being stored in a sealed, light-protected environment for over 6 months, it maintains a uniform state without deterioration issues such as layering or gelling, allowing for direct use without frequent formula adjustments. During application, the coating viscosity is suitable for common methods such as scraping and rolling, avoiding both excessively low viscosity (causing sagging on vertical surfaces) and excessively high viscosity (ensuring even coating uniformity). The film-forming process is less prone to defects such as pinholes and bubbles, resulting in a uniform film thickness and smooth surface, eliminating the need for subsequent repairs. This significantly reduces application difficulty and cost, addressing the pain points of traditional composite coatings, such as easy storage failure and application problems.

[0041] 3. This invention scientifically designs the modification process of nano-silica and polypropylene glycol, abandoning traditional operations that easily lead to performance fluctuations, ensuring that the modified raw materials can accurately match the requirements of the coating system. Modified nano-silica, through covalent grafting of organic functional groups, significantly improves its compatibility with epoxy resins and polyurethanes, achieving uniform dispersion without relying on large amounts of dispersants, thus avoiding coating defects caused by filler agglomeration. Modified polypropylene glycol, through controllable functionalization treatment, maintains the integrity and stable functionality of the molecular chain, ensuring the formation of a uniform cross-linked structure when reacting with isocyanates. This makes the mechanical properties and media resistance of the coating film stable and controllable, preventing problems such as insufficient strength and decreased corrosion resistance due to poor raw material modification, ensuring consistent performance of each batch of products.

[0042] 4. After curing, the coating forms a composite film structure of "organic cross-linked network - inorganic reinforcing phase," which combines high stability and strong anti-aging ability. The three-dimensional cross-linked network formed by epoxy resin and polyamide, combined with the elasticity of polyurethane segments and the crack resistance of SBS, makes the coating film less prone to shrinkage and cracking during long-term use. Modified nano-silica is uniformly dispersed in the coating film, acting as a "reinforcing skeleton" to improve structural stability and reduce damage to the coating film from the external environment. The synergistic effect of fluorine-containing groups and passivation protective film can resist the erosion of corrosive media for a long time, avoiding problems such as chalking, peeling, and degradation of protective performance that occur after long-term use of traditional coatings, effectively extending the service life of the substrate and reducing the frequency and cost of later maintenance. Detailed Implementation

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1: Preparation of a corrosion-resistant polymer composite waterproof coating. The specific preparation steps are as follows:

[0045] S1. Take 40 parts of styrene-butadiene-styrene block copolymer and 10 parts of dioctyl phthalate and add them to a high-speed mixer. Stir at 80°C and 800 r / min for 30 min until the styrene-butadiene-styrene block copolymer is completely swollen. Then add 3 parts of fumed silica and 1 part of sodium benzoate and continue stirring at 1000 r / min for 20 min to form a uniform premix A.

[0046] S2. Take 25 parts of epoxy resin E-51 and add it to the reactor. Heat the temperature to 60℃ and slowly add 8 parts of nano silica. Stir at 1500r / min for 40min and simultaneously use 400W ultrasonication for 5min with a 2min pause for 20min to ensure uniform dispersion of nano silica and obtain matrix B.

[0047] S3. Take 15 parts of polypropylene glycol, 8 parts of toluene diisocyanate, and 3 parts of dimethylolpropionic acid and add them to the reactor. Heat the mixture to 80°C, then add 1 part of triethanolamine. Stir the mixture at 700 r / min for 2 hours. Stop the reaction when the isocyanate group content reaches 8% by chemical titration. Cool the mixture to 40°C, add 2 parts of triethylamine, and stir at 500 r / min for 15 minutes. Then, under high-speed shear at 2500 r / min, slowly add 40 parts of deionized water and emulsify for 30 minutes to obtain waterborne polyurethane dispersion C.

[0048] S4. Slowly add premix A to matrix B, stir at 70℃ and 1200 r / min for 60 min, then cool to 55℃, add waterborne polyurethane dispersion C and 20 parts of polyamide 650 in sequence, stir at 1000 r / min for 40 min, finally add 5 parts of zinc phosphate, and continue stirring at 800 r / min for 30 min; maintain 55℃, reduce the speed to 500 r / min, and continue stirring for 2 h; slowly add 3 parts of phenyl glycidyl ether, stir at 600 r / min for 20 min, and adjust the viscosity to 5000 mPa·s;

[0049] S5. Stop heating, cool to room temperature, filter with a 100-mesh filter to remove impurities and undispersed particles, dispense into sealed containers, and store away from light to obtain corrosion-resistant polymer composite waterproof coating.

[0050] Example 2: Preparation of a corrosion-resistant polymer composite waterproof coating. The specific preparation steps are as follows:

[0051] S1. Take 60 parts of styrene-butadiene-styrene block copolymer and 18 parts of dioctyl phthalate and add them to a high-speed mixer. Stir at 90°C and 1000 r / min for 40 min until the styrene-butadiene-styrene block copolymer is completely swollen. Then add 8 parts of fumed silica and 3 parts of sodium benzoate and continue stirring at 1200 r / min for 30 min to form a uniform premix A.

[0052] S2. Take 35 parts of epoxy resin E-51 and add it to the reactor. Heat the reactor to 70℃ and slowly add 15 parts of nano silica. Stir at 2000r / min for 50min and simultaneously use 400W ultrasonication for 5min followed by 2min interval ultrasonic dispersion for 30min to ensure uniform dispersion of nano silica and obtain matrix B.

[0053] S3. Take 25 parts of polypropylene glycol, 12 parts of toluene diisocyanate, and 6 parts of dimethylolpropionic acid and add them to the reactor. Heat the mixture to 90°C, then add 4 parts of triethanolamine. Stir the mixture at 800 r / min for 3 h. Stop the reaction when the isocyanate group content reaches 10% by chemical titration. Cool the mixture to 50°C, add 4 parts of triethylamine, and stir at 600 r / min for 20 min. Then, under high-speed shear at 3000 r / min, slowly add 60 parts of deionized water and emulsify for 40 min to obtain waterborne polyurethane dispersion C.

[0054] S4. Slowly add premix A to matrix B, stir at 80℃ and 1500 r / min for 80 min, then cool to 55℃, add waterborne polyurethane dispersion C and 35 parts of polyamide 650 in sequence, stir at 1200 r / min for 50 min, finally add 10 parts of zinc phosphate, and continue stirring at 1000 r / min for 40 min; maintain 55℃, reduce the speed to 800 r / min, and continue stirring for 3 h; slowly add 8 parts of phenyl glycidyl ether, stir at 700 r / min for 30 min, and adjust the viscosity to 8000 mPa·s;

[0055] S5. Stop heating, cool to room temperature, filter with a 120-mesh filter to remove impurities and undispersed particles, dispense into sealed containers, and store away from light to obtain corrosion-resistant polymer composite waterproof coating.

[0056] Example 3: Preparation of a corrosion-resistant polymer composite waterproof coating. The specific preparation steps are as follows:

[0057] S1. Take 50 parts of styrene-butadiene-styrene block copolymer and 14 parts of dioctyl phthalate and add them to a high-speed mixer. Stir at 85°C and 900 r / min for 35 min until the styrene-butadiene-styrene block copolymer is completely swollen. Then add 5 parts of fumed silica and 2 parts of sodium benzoate and continue stirring at 1100 r / min for 25 min to form a uniform premix A.

[0058] S2. Take 30 parts of epoxy resin E-51 and add it to the reactor. Heat the temperature to 65℃ and slowly add 11 parts of nano silica. Stir at 1750r / min for 45min and simultaneously use 400W ultrasonication for 5min with a 2min pause for 25min to ensure uniform dispersion of nano silica and obtain matrix B.

[0059] S3. Take 20 parts of polypropylene glycol, 10 parts of toluene diisocyanate, and 5 parts of dimethylolpropionic acid and add them to the reactor. Heat the mixture to 85°C, then add 2 parts of triethanolamine. Stir the mixture at 750 r / min for 2.5 h. Stop the reaction when the isocyanate group content reaches 9% by chemical titration. Cool the mixture to 45°C, add 3 parts of triethylamine, and stir at 550 r / min for 17 min. Then, slowly add 50 parts of deionized water under high-speed shear at 2750 r / min and emulsify for 35 min to obtain waterborne polyurethane dispersion C.

[0060] S4. Slowly add premix A to matrix B, stir at 75°C and 1350 r / min for 70 min, then cool to 55°C, add waterborne polyurethane dispersion C and 26 parts of polyamide 650 in sequence, stir at 1100 r / min for 45 min, finally add 7 parts of zinc phosphate, and continue stirring at 900 r / min for 35 min; maintain 55°C, reduce the speed to 650 r / min, and continue stirring for 2.5 h; slowly add 5 parts of phenyl glycidyl ether, stir at 650 r / min for 25 min, and adjust the viscosity to 6500 mPa·s;

[0061] S5. Stop heating, cool to room temperature, filter with a 110-mesh filter to remove impurities and undispersed particles, dispense into sealed containers, and store away from light to obtain corrosion-resistant polymer composite waterproof coating.

[0062] Example 4: Preparation of modified nano-silica. The specific preparation steps are as follows:

[0063] A1. Add 100g of nano-silica to a reaction vessel, then add 150mL of deionized water, stir at 300r / min and sonicate for 25min to form a suspension; then add 50mL of 0.5mol / L nitric acid dropwise, heat to 60℃, stir at 500r / min for 2h to complete hydroxyl activation; after the reaction, filter the product and wash with deionized water until neutral, then vacuum dry at 75℃ for 3h to obtain hydroxyl-activated nano-silica;

[0064] A2. Add 100 mL of anhydrous ethanol and 8 g of silane coupling agent KH-550 to the hydroxyl-activated nano silica prepared in A1, heat to 70 °C, and stir at 600 r / min for 4 h. After the reaction is complete, filter the product and dry it under vacuum at 75 °C for 3 h to obtain amino-modified nano silica.

[0065] A3. Add 100 mL of toluene and 10 g of epichlorohydrin to the amino-modified nano silica prepared in A2, heat to 80 °C, and stir at 700 r / min for 5 h. Then add 2 g of titanate coupling agent NDZ-101 and continue stirring at 700 r / min for 1 h. After the reaction, remove toluene by vacuum distillation at -0.09 MPa and 60 °C for 1.5 h to make the viscosity at 25 °C 1800 mPa·s, thus obtaining modified nano silica.

[0066] Example 5: Preparation of modified nano-silica. The specific preparation steps are as follows:

[0067] A1. Add 100g of nano-silica to a reaction vessel, then add 200mL of deionized water, stir at 400r / min and sonicate for 35min to form a suspension; then add 60mL of 0.5mol / L nitric acid dropwise, heat to 70℃, stir at 500r / min for 2h to complete hydroxyl activation; after the reaction, filter the product and wash with deionized water until neutral, then vacuum dry at 85℃ for 4h to obtain hydroxyl-activated nano-silica;

[0068] A2. Add 100 mL of anhydrous ethanol and 12 g of silane coupling agent KH-550 to the hydroxyl-activated nano silica prepared in A1, heat to 70 °C, and stir at 600 r / min for 5 h. After the reaction is complete, filter the product and dry it under vacuum at 85 °C for 4 h to obtain amino-modified nano silica.

[0069] A3. Add 100 mL of toluene and 15 g of epichlorohydrin to the amino-modified nano silica prepared in A2, heat to 80 °C, and stir at 700 r / min for 6 h. Then add 5 g of titanate coupling agent NDZ-101 and continue stirring at 700 r / min for 1 h. After the reaction, remove toluene by vacuum distillation at -0.09 MPa and 70 °C for 2.5 h to make the viscosity at 25 °C 2500 mPa·s, thus obtaining modified nano silica.

[0070] Example 6: Preparation of modified polypropylene glycol. The specific preparation steps are as follows:

[0071] B1. Add 100g of polypropylene glycol to a reaction vessel, heat to 80℃, add 3g of toluene diisocyanate and 0.1g of dibutyltin dilaurate, and stir at a constant temperature of 600r / min for 2h; monitor by gel permeation chromatography to ensure that the number average molecular weight is maintained at 1800-2000 and the distribution is ≤1.2, then stop the reaction to obtain end-group activated polypropylene glycol;

[0072] B2. Add the end-group activated polypropylene glycol prepared in B1 to 80 mL of toluene, heat to 80 °C, and stir at 500 r / min until completely dissolved; add 8 g of N-phenylmaleimide and 0.5 g of benzoyl peroxide, purge with nitrogen for protection, heat to 90 °C, and stir at 700 r / min for 3 h; after the reaction is complete, remove toluene by vacuum distillation at -0.09 MPa and 90 °C for 1.5 h to obtain block copolymer polypropylene glycol;

[0073] B3. Add the block copolymer polypropylene glycol prepared in B2 to 50 mL of toluene, heat to 80 °C, and stir at 500 r / min until dissolved; add 5 g of trifluoroethanol dropwise, and stir at 80 °C at 800 r / min for 4 h; after completion, add deionized water, stir and wash twice at 400 r / min, and separate the organic phase after standing and layering; remove toluene from the organic phase by vacuum distillation at -0.08 MPa and 70 °C for 1 h, and dry under vacuum at 80 °C for 5 h to obtain modified polypropylene glycol.

[0074] Example 7: Preparation of modified polypropylene glycol. The specific preparation steps are as follows:

[0075] B1. Add 100g of polypropylene glycol to a reaction vessel, heat to 80℃, add 5g of toluene diisocyanate and 0.1g of dibutyltin dilaurate, and stir at a constant temperature of 600r / min for 2h; monitor by gel permeation chromatography to ensure that the number average molecular weight is maintained at 1800-2000 and the distribution is ≤1.2, then stop the reaction to obtain end-group activated polypropylene glycol;

[0076] B2. Add the end-group activated polypropylene glycol prepared in B1 to 80 mL of toluene, heat to 80 °C, and stir at 600 r / min until completely dissolved; add 10 g of N-phenylmaleimide and 1 g of benzoyl peroxide, purge with nitrogen for protection, heat to 90 °C, and stir at 800 r / min for 3 h; after the reaction is complete, remove toluene by vacuum distillation at -0.09 MPa and 90 °C for 2 h to obtain block copolymer polypropylene glycol;

[0077] B3. Add the block copolymer polypropylene glycol prepared in B2 to 50 mL of toluene, heat to 80 °C, and stir at 500 r / min until dissolved; add 8 g of trifluoroethanol dropwise, and stir at 80 °C and 800 r / min for 4 h; after completion, add deionized water, stir and wash 3 times at 500 r / min, and separate the organic phase after standing and layering; remove toluene from the organic phase by vacuum distillation at -0.08 MPa and 70 °C for 1.5 h, and dry under vacuum at 90 °C for 7 h to obtain modified polypropylene glycol.

[0078] Comparative Example 1: A corrosion-resistant polymer composite waterproof coating was prepared. The specific preparation steps are as follows:

[0079] The remaining steps remain unchanged, except that the nano-silica in Example 3 is replaced with the modified nano-silica prepared in Example 4 to prepare a corrosion-resistant polymer composite waterproof coating.

[0080] Comparative Example 2: A corrosion-resistant polymer composite waterproof coating was prepared. The specific preparation steps are as follows:

[0081] The remaining steps remain unchanged, except that the polypropylene glycol in Example 3 is replaced with the modified polypropylene glycol prepared in Example 7 to prepare a corrosion-resistant polymer composite waterproof coating.

[0082] Comparative Example 3: A corrosion-resistant polymer composite waterproof coating was prepared. The specific preparation steps are as follows:

[0083] The remaining steps remain unchanged, except that the nano-silica in Example 3 is replaced with the modified nano-silica prepared in Example 4, and the polypropylene glycol is replaced with the modified polypropylene glycol prepared in Example 7, to prepare a corrosion-resistant polymer composite waterproof coating.

[0084] Performance testing

[0085] Test item Test standard Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile strength (MPa) GB / T 16777-2008 1.8 2.2 2.8 3.5 3.6 4.2 Elongation at break (%) GB / T 16777-2008 150 220 250 300 320 360 Salt spray resistance (h, no rust) GB / T 10125-2021 (5% NaCl) 200 280 320 400 420 500 Resistance to 5% hydrochloric acid (72h appearance) GB / T 16777-2008 Slight bubbling No bubbling, partial loss of luster No bubbling, slight loss of luster No bubbling, no loss of luster No bubbling, no loss of luster No bubbling, no loss of luster Resistance to 5% sodium hydroxide (72h appearance) GB / T 16777-2008 Partial whitening No whitening, slight softening No whitening, no softening No whitening, no softening No whitening, no softening No whitening, no softening Storage stability (months, no delamination) GB / T 6753.3-1986 2 3 4 5 5 6 Coating film adhesion (crosshatch method, grade) GB / T 9286-2021 3 2 2 1 1 0

[0086] Based on the performance test results, the overall performance of the coating showed a significant improvement trend with the optimization of the formula and the gradual addition of modified raw materials. In terms of basic mechanical properties, the tensile strength increased from 2.8 MPa in Example 3 to 4.2 MPa in Comparative Example 3, and the elongation at break increased from 250% to 360%, significantly enhancing flexibility and tensile strength. Regarding corrosion resistance, the salt spray resistance time increased from 320 h to 500 h, and the resistance to 5% hydrochloric acid and 5% sodium hydroxide improved from no bubbling and slight loss of gloss to no visible abnormalities, indicating a substantial improvement in corrosion resistance. Storage stability increased from 4 months to 6 months, and the coating adhesion improved from level 2 to level 0. Both system stability and substrate adhesion were optimized. Comparative Example 3, which used two modified raw materials simultaneously, performed best in all performance tests, fully demonstrating the synergistic effect of the modified raw materials on coating performance.

[0087] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A corrosion-resistant polymer composite waterproof coating, characterized in that: It contains the following raw materials in parts by weight: 40-60 parts styrene-butadiene-styrene block copolymer, 25-35 parts epoxy resin E-51, 8-15 parts modified nano silica, 15-25 parts modified polypropylene glycol, 8-12 parts toluene diisocyanate, 5-10 parts zinc phosphate, 10-18 parts dioctyl phthalate, 3-8 parts fumed silica, 1-3 parts sodium benzoate, 3-6 parts dimethylolpropionic acid, 1-4 parts triethanolamine, 2-4 parts triethylamine, 20-35 parts polyamide 650, 3-8 parts phenyl glycidyl ether, and 40-60 parts deionized water; The modified nano-silica is prepared using the following specific steps: A1. Add nano-silica to a reaction vessel, then add deionized water, stir at 300-400 rpm while ultrasonically dispersing for 25-35 min to form a suspension; then add 50-60 mL of 0.5 mol / L nitric acid dropwise, raise the temperature to 60-70℃, and stir at 500 rpm for 2 h to complete hydroxyl activation; after the reaction is complete, filter the product and wash it with deionized water until neutral, then vacuum dry at 75-85℃ for 3-4 h to obtain hydroxyl-activated nano-silica; A2. Add anhydrous ethanol and silane coupling agent KH-550 to the hydroxyl-activated nano silica prepared in A1, heat to 70℃, and stir at 600r / min for 4-5h. After the reaction is complete, filter the product and dry it under vacuum at 75-85℃ for 3-4h to obtain amino-modified nano silica. A3. Toluene and epichlorohydrin were added to the amino-modified nano-silica prepared in A2. The mixture was heated to 80°C and stirred at a constant speed of 700 r / min for 5-6 h. Then, titanate coupling agent NDZ-101 was added, and stirring was continued at 700 r / min for 1 h. After the reaction was completed, toluene was removed by vacuum distillation at a vacuum degree of -0.09 MPa and a temperature of 60-70°C for 1.5-2.5 h, so that the viscosity at 25°C was 1800-2500 mPa·s, thus obtaining modified nano-silica. The modified polypropylene glycol is prepared using the following specific steps: B1. Add polypropylene glycol to the reaction vessel, heat to 80°C, add toluene diisocyanate and dibutyltin dilaurate, and stir at 600 r / min for 2 h. Monitor by gel permeation chromatography to ensure that the number average molecular weight is maintained at 1800-2000 and the distribution is ≤1.

2. Stop the reaction to obtain end-group activated polypropylene glycol. B2. Add the end-group activated polypropylene glycol prepared in B1 to toluene, heat to 80℃, and stir at 500-600 r / min until completely dissolved; add N-phenylmaleimide and benzoyl peroxide, purge with nitrogen for protection, heat to 90℃, and stir at 700-800 r / min for 3 h; after the reaction is complete, remove toluene by vacuum distillation at -0.09 MPa and 90℃ for 1.5-2 h to obtain block copolymer polypropylene glycol; B3. Add the block copolymer polypropylene glycol prepared in B2 to toluene, heat to 80℃, and stir at 500 r / min until dissolved; add trifluoroethanol dropwise, and stir at 800 r / min at 80℃ for 4 h; after completion, add deionized water, stir and wash 2-3 times at 400-500 r / min, and separate the organic phase after standing and layering; remove toluene from the organic phase by vacuum distillation at -0.08 MPa and 70℃ for 1-1.5 h, and vacuum dry at 80-90℃ for 5-7 h to obtain modified polypropylene glycol.

2. The corrosion-resistant polymer composite waterproof coating according to claim 1, characterized in that: The fumed silica is a hydrophilic fumed silica with a specific surface area of ​​200-300 m². 2 / g; The purity of the sodium benzoate is ≥99%, and its weight ratio with fumed silica is (1-3):(3-8).

3. The corrosion-resistant polymer composite waterproof coating according to claim 1, characterized in that: The ratio of nano-silica to deionized water in A1 is 100g: 150-200mL; The ratio of anhydrous ethanol to silane coupling agent KH-550 in A2 is 100mL:8-12g; The ratio of toluene, epichlorohydrin, and titanate coupling agent NDZ-101 in A3 is 100mL: 10-15g: 2-5g.

4. The corrosion-resistant polymer composite waterproof coating according to claim 1, characterized in that: The ratio of polypropylene glycol, toluene diisocyanate, and dibutyltin dilaurate in B1 is 100g: 3-5g: 0.1g; The ratio of toluene, N-phenylmaleimide, and benzoyl peroxide in B2 is 80 mL: 8-10 g: 0.5-1 g; The ratio of toluene to trifluoroethanol in B3 is 50 mL: 5-8 g.

5. A method for preparing a corrosion-resistant polymer composite waterproof coating, characterized in that: Specifically, it includes the following steps: S1. Add styrene-butadiene-styrene block copolymer and dioctyl phthalate to a high-speed mixer and stir at 80-90℃ and 800-1000r / min for 30-40min until the styrene-butadiene-styrene block copolymer is completely swollen; then add fumed silica and sodium benzoate and continue stirring at 1000-1200r / min for 20-30min to form a uniform premix A. S2. Add epoxy resin E-51 to the reactor, heat to 60-70℃, slowly add modified nano silica, stir at high speed of 1500-2000r / min for 40-50min, and simultaneously ultrasonically disperse for 20-30min to ensure uniform dispersion of modified nano silica, and obtain matrix B. S3. Add modified polypropylene glycol, toluene diisocyanate, and dimethylolpropionic acid to a reaction vessel, heat to 80-90℃, then add triethanolamine, stir at 700-800 r / min for 2-3 h, and stop when the isocyanate group content reaches 8-10% by chemical titration; cool to 40-50℃, add triethylamine, stir at 500-600 r / min for 15-20 min; then slowly add deionized water under high-speed shear at 2500-3000 r / min, emulsify for 30-40 min, and obtain waterborne polyurethane dispersion C; S4. Slowly add premix A to matrix B, stir at 70-80℃ and 1200-1500 r / min for 60-80 min, then cool to 55℃, add waterborne polyurethane dispersion C and polyamide 650 in sequence, stir at 1000-1200 r / min for 40-50 min, finally add zinc phosphate, continue stirring at 800-1000 r / min for 30-40 min; maintain 55℃, reduce the speed to 500-800 r / min, and continue stirring for 2-3 h; slowly add phenyl glycidyl ether, stir at 600-700 r / min for 20-30 min, and adjust the viscosity to 5000-8000 mPa·s; S5. Stop heating, cool to room temperature, filter with a 100-120 mesh filter to remove impurities and undispersed particles, dispense into sealed containers, and store away from light to obtain corrosion-resistant polymer composite waterproof coating.

6. The method for preparing a corrosion-resistant polymer composite waterproof coating according to claim 5, characterized in that: The ultrasonic dispersion power in S2 is 400W, and the ultrasonic process adopts an intermittent ultrasonic method of 5 minutes of ultrasonication followed by 2 minutes of rest.

7. The method for preparing a corrosion-resistant polymer composite waterproof coating according to claim 5, characterized in that: The filtered coating in S5 needs to be left to stand for 2 hours at 25°C and 40% relative humidity, allowing the tiny bubbles in the system to escape naturally before being packaged.