Building waterproof coating and preparation method thereof

Abstract

The invention relates to the technical field of coating preparation, in particular to a waterproof coating for buildings and a preparation method of the waterproof coating for the buildings. And in combination with multifunctional nano components such as a surface modified silicon dioxide / graphene oxide compound, coating modified titanium dioxide and surface fluorinated modified cellulose whiskers, excellent comprehensive performance is realized. Wherein the organosilicone endows a coating with super-hydrophobicity and weather resistance, the epoxy resin enhances adhesive force and cross-linking density, the polypropylene glycol and polycarbonate diol double soft segment design gives consideration to flexibility and hydrolysis resistance, and on the basis, the reasonable compatibility of the coalescing agent, the defoaming agent and the flatting agent ensures good construction performance and film forming quality of the coating. And practical engineering application requirements are met.

Description

Technical Field

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

[0002] With the growing emphasis on green building and sustainable development, water-based waterproof coatings have gradually become the mainstream development direction in the building waterproofing field due to their advantages such as low VOCs, non-toxicity, and safe construction. However, traditional water-based polyurethane or acrylic waterproof coatings generally suffer from insufficient water resistance, difficulty in balancing mechanical properties and flexibility, and susceptibility to aging after long-term service. Especially in complex climatic environments or high-humidity conditions, the coating is prone to swelling, cracking, or peeling, leading to waterproofing failure. Furthermore, existing products often rely on single-function designs and lack composite properties such as self-cleaning, stain resistance, and crack resistance, making it difficult to meet the demands of modern buildings for high-performance, long-life protective systems.

[0003] To improve the overall performance of waterborne waterproof coatings, researchers have attempted to modify them by introducing nanofillers such as silica, graphene oxide, or titanium dioxide. However, these inorganic particles tend to aggregate in aqueous systems and have poor compatibility with organic matrices, which negatively impacts film density and stability. While some photocatalytic fillers, such as nano-TiO2, possess self-cleaning potential, they may accelerate the photodegradation of the polymer matrix. Furthermore, simple physical blending fails to achieve synergistic effects between components, resulting in limited performance improvements. Therefore, there is an urgent need to develop a new generation of waterborne waterproof coating systems that combine high durability, toughness, superhydrophobicity, and environmental responsiveness through molecular structure design, interfacial compatibility control, and multi-scale composite strategies. Summary of the Invention

[0004] Technical problems to be solved

[0005] In view of the above-mentioned shortcomings of the existing technology, the present invention provides a waterproof coating for building and its preparation method, which can effectively solve the problems of poor environmental protection and insufficient water resistance of the existing water-based waterproof coatings.

[0006] Technical solution

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

[0008] A waterproof coating for building applications, comprising: epoxy resin / organosilicon composite modified waterborne polyurethane, surface modified silica / graphene oxide composite, coated modified titanium dioxide, surface fluorinated modified cellulose whiskers, film-forming agent, defoamer, and leveling agent.

[0009] The epoxy resin / organosilicon composite modified waterborne polyurethane is prepared using organosilicon modified waterborne polyurethane prepolymer and epoxy resin as the main raw materials.

[0010] The surface-modified silica / graphene oxide composite was prepared by coating graphene oxide with surface-modified silica.

[0011] The coated and modified titanium dioxide is prepared by coating and modifying nano-titanium dioxide with sodium silicate.

[0012] The surface-fluorinated modified cellulose whiskers are obtained by surface modification of cellulose whiskers.

[0013] Furthermore, the preparation steps of the organosilicon-modified waterborne polyurethane prepolymer are as follows:

[0014] Step A: Weigh 2.4-3 parts by weight of polypropylene glycol, 1.6-2 parts by weight of polycarbonate glycol, 3.5-4 parts by weight of amino silicone oil and 9-11 parts by weight of isoflurone diisocyanate and pour them into a flask. After stirring and mixing, heat to 70°C and add 0.04-0.05 parts by weight of dibutyltin dilaurate. Keep the temperature for 2 hours and then cool to 50°C. The result is recorded as the reaction component.

[0015] Step B: Add 1.2-1.5 parts by weight of 1,4-butanediol and 0.7-1 parts by weight of 2,2-dimethylolpropionic acid to the reaction components. Add the calculated amount of acetone to adjust the viscosity to the preset value and keep it at the temperature for 5 minutes. Then raise the temperature to 70°C and keep it at the temperature for 2 hours. The result is the organosilicon-modified waterborne polyurethane prepolymer.

[0016] Furthermore, the mixing method in step A is to stir at a stirring speed of 300-500 r / min for 30 min.

[0017] Furthermore, the preparation steps of the epoxy resin / organosilicon composite modified waterborne polyurethane are as follows:

[0018] Add 5-7 parts by weight of epoxy resin to 100 parts by weight of silicone-modified waterborne polyurethane prepolymer, react at 70°C for 100 min, then cool to 50°C, add 3-3.5 parts by weight of triethylamine and keep reacting at 70°C for 30 min, then add 170-190 parts by weight of deionized water and stir at 800-1000 r / min for 30 min. The result is epoxy resin / silicone composite modified waterborne polyurethane.

[0019] Furthermore, the preparation steps of the surface-modified silica are as follows:

[0020] Step 1: Weigh 3-4 parts by weight of nano-silica and disperse it in 100 parts by weight of anhydrous ethanol. After ultrasonic dispersion, the resulting solution is recorded as a suspension. Weigh 0.08-0.12 parts by weight of 3-aminopropyltriethoxysilane, 0.08-0.12 parts by weight of γ-glycidoxypropyltrimethoxysilane, and 0.08-0.12 parts by weight of γ-methacryloyloxypropyltrimethoxysilane and dissolve them in 20 parts by weight of anhydrous ethanol. After hydrolysis at room temperature for 30 minutes, the resulting solution is recorded as the hydrolysate.

[0021] Step 2: Pour the hydrolyzed components into the suspension and adjust the pH value to 4-5 with hydrochloric acid solution. Then heat to 75℃ and stir magnetically for 6 hours. After cooling to room temperature, wash with anhydrous ethanol and deionized water three times in sequence by centrifugation. Dry at 60℃ for 12 hours to obtain surface-modified silica.

[0022] Furthermore, the preparation method of the surface-modified silica / graphene oxide composite is as follows:

[0023] Weigh 0.2-0.3 parts by weight of surface-modified silica and disperse it in 200 parts by weight of N,N-dimethylformamide. After ultrasonic dispersion into a suspension, add 0.3-0.5 parts by weight of graphene oxide and ultrasonically disperse again for 1 hour. Then, react in an oil bath at 105°C for 6 hours. After the reaction is complete, wash the silica / graphene oxide composite by centrifugation three times with anhydrous ethanol and deionized water, and dry it at 60°C for 24 hours.

[0024] Furthermore, the preparation method of the coated modified titanium dioxide is as follows:

[0025] Nano-titanium dioxide was dispersed in deionized water to prepare a suspension with a mass fraction of 1.5%. Then, 0.02-0.05 parts by weight of sodium hexametaphosphate were added to 100 parts by weight of the suspension. After ultrasonic dispersion, the suspension was heated to 80-90℃ and 4-5 parts by weight of sodium silicate solution containing 26% silicon dioxide were added dropwise. The pH value was adjusted to 8-10 by adding 10% by weight of sulfuric acid solution. After aging at this temperature for 2 hours, the suspension was dried at 120℃ for 12 hours. The resulting product is coated modified titanium dioxide.

[0026] Furthermore, the preparation steps of the surface-fluorinated modified cellulose whiskers are as follows:

[0027] Step 1: Weigh 5-6 parts by weight of microcrystalline cellulose and immerse it in a 54% sulfuric acid solution. Stir the solution with ultrasonic assistance and magnetic stirring at 52°C for 2 hours. After the reaction is complete, pour in a large amount of deionized water to terminate the reaction. Centrifuge to collect the precipitate and dialyze it to neutral. After freeze-drying, cellulose nanofibers are obtained.

[0028] Step II: Weigh 2-3 parts by weight of cellulose whiskers and pour them into 100 parts by weight of toluene. After stirring and dispersing, add 0.4-0.6 parts by weight of heptadecafluorodecyltrimethoxysilane. React at 70°C for 2-6 hours. Filter the reaction solution with a polyvinylidene fluoride membrane and wash it with toluene 3-5 times. Dry it at 45°C for 2 hours to obtain the surface-fluorinated modified cellulose whiskers.

[0029] A method for preparing a waterproof coating for building applications, wherein the preparation method comprises:

[0030] S1. Weigh 0.8-1.2 parts by weight of surface-modified silica / graphene oxide composite, 0.5-1 parts by weight of coated modified titanium dioxide, and 0.3-0.6 parts by weight of surface-fluorinated modified cellulose whiskers and pour them into 18-20 parts by weight of deionized water. The result after dispersion treatment is recorded as the composite dispersion component.

[0031] S2. Add 100 parts by weight of epoxy resin / organosilicon composite modified waterborne polyurethane to a mixing tank, add 2-4 parts by weight of film-forming agent and stir to disperse. Add the composite dispersion components under the original stirring speed, then add 0.1-0.3 parts by weight of defoamer and 0.1-0.2 parts by weight of leveling agent in sequence. Heat to 40℃ and stir at 800-1000 r / min for 45 min. Adjust the pH value to 7.5-8.5 and then cool to 25℃. After standing and curing for 2 hours, filter through a 200-mesh stainless steel screen. The result is a waterproof coating for building applications.

[0032] Furthermore, the dispersion treatment in S1 involves stirring at a speed of 400-500 r / min for 10 min, followed by ultrasonic dispersion at a power of 300 W for 30 min. The dispersion treatment in S2 involves stirring at a speed of 400-600 r / min for 20 min. In S2, the pH value is adjusted using a 1% ammonia solution and a 1% acetic acid solution.

[0033] Beneficial effects

[0034] This invention provides a waterproof coating for building applications and its preparation method. Compared with existing technologies, this invention has the following advantages:

[0035] This invention provides a waterproof coating for construction, which uses epoxy resin / organosilicon composite modified waterborne polyurethane as the matrix, combined with multifunctional nano-components such as surface-modified silica / graphene oxide composite, coated modified titanium dioxide, and surface-fluorinated modified cellulose whiskers, achieving excellent comprehensive performance. Specifically, the organosilicon imparts superhydrophobicity and weather resistance to the coating, the epoxy resin enhances adhesion and crosslinking density, and the dual soft-segment design of polypropylene glycol and polycarbonate glycol balances flexibility and hydrolysis resistance. Furthermore, the rational formulation of film-forming aids, defoamers, and leveling agents ensures good application performance and film quality, meeting the needs of practical engineering applications.

[0036] A multi-scale synergistic enhancement mechanism is formed among the various functional fillers. The surface-modified silica / graphene oxide composite constructs a "sheet-particle" barrier network, which significantly extends the water molecule penetration path. The surface-fluorinated modified cellulose whiskers form a three-dimensional skeleton in the coating with their high-modulus rod-like structure, which not only improves mechanical strength, but also further enhances the hydrophobic effect with their fluorinated surface. The coated modified titanium dioxide exerts a photocatalytic self-cleaning function without damaging the polymer matrix, effectively resisting stain adhesion and biological erosion. The three work together to build a dense, stable and long-lasting protective barrier at the nano, micro and macro levels.

[0037] Thanks to the scientific formulation and structural design of the above components, the coating of this invention exhibits outstanding technical effects, combining high strength, high elasticity, and ultra-low water permeability. Furthermore, the coating of this invention not only breaks through the limitations of traditional water-based waterproof coatings in terms of durability and functionality, but also provides an innovative solution for high-performance, intelligent building waterproof materials through its all-water-based, highly environmentally friendly green formula. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0039] The present invention will be further described below with reference to embodiments.

[0040] Example 1

[0041] This embodiment provides a waterproof coating for building applications. The composition of the waterproof coating includes: epoxy resin / organosilicon composite modified waterborne polyurethane, surface modified silica / graphene oxide composite, coated modified titanium dioxide, surface fluorinated modified cellulose whiskers, film-forming agent, defoamer, and leveling agent.

[0042] The epoxy / silicone composite modified waterborne polyurethane is prepared using silicone-modified waterborne polyurethane prepolymer and epoxy resin as the main raw materials.

[0043] The preparation steps of silicone-modified waterborne polyurethane prepolymer are as follows:

[0044] Step A: Weigh 2.4 parts by weight of polypropylene glycol, 1.6 parts by weight of polycarbonate glycol, 3.5 parts by weight of amino silicone oil and 9 parts by weight of isoflurane diisocyanate and pour them into a flask. Stir at 300 r / min for 30 min, then heat to 70℃ and add 0.04 parts by weight of dibutyltin dilaurate. Keep the temperature for 2 h and then cool to 50℃. The result is recorded as the reaction component.

[0045] Step B: Add 1.2 parts by weight of 1,4-butanediol and 0.7 parts by weight of 2,2-dihydroxymethylpropionic acid to the reaction components. Add the calculated amount of acetone to adjust the viscosity to the preset value and keep it at the temperature for 5 minutes. Then raise the temperature to 70°C and keep it at the temperature for 2 hours. The result is the organosilicon-modified waterborne polyurethane prepolymer.

[0046] The preparation steps for epoxy resin / organic silicone composite modified waterborne polyurethane are as follows:

[0047] Add 5 parts by weight of epoxy resin to 100 parts by weight of silicone-modified waterborne polyurethane prepolymer, react at 70°C for 100 min, then cool to 50°C, add 3 parts by weight of triethylamine and keep reacting for 30 min, add 170 parts by weight of deionized water and stir at 800 r / min for 30 min. The result is epoxy resin / silicone composite modified waterborne polyurethane.

[0048] The surface-modified silica / graphene oxide composite was prepared by coating graphene oxide with surface-modified silica.

[0049] The preparation steps for surface-modified silica are as follows:

[0050] Step 1: Weigh 3 parts by weight of nano-silica and disperse it in 100 parts by weight of anhydrous ethanol. After ultrasonic dispersion, the resulting solution is recorded as a suspension. Weigh 0.08 parts by weight of 3-aminopropyltriethoxysilane, 0.08 parts by weight of γ-glycidoxypropyltrimethoxysilane, and 0.08 parts by weight of γ-methacryloyloxypropyltrimethoxysilane and dissolve them in 20 parts by weight of anhydrous ethanol. After hydrolysis at room temperature for 30 minutes, the resulting solution is recorded as the hydrolysate.

[0051] Step 2: Pour the hydrolyzed component into the suspension and adjust the pH value to 4 with hydrochloric acid solution. Then heat to 75℃ and stir magnetically for 6 hours. After cooling to room temperature, wash with anhydrous ethanol and deionized water three times in sequence by centrifugation. Dry at 60℃ for 12 hours to obtain surface-modified silica.

[0052] The preparation method of surface-modified silica / graphene oxide composite is as follows:

[0053] 0.2 parts by weight of surface-modified silica were dispersed in 200 parts by weight of N,N-dimethylformamide and ultrasonically dispersed into a suspension. Then, 0.3 parts by weight of graphene oxide were added and ultrasonically dispersed again for 1 hour. The mixture was then placed in an oil bath at 105°C and reacted for 6 hours. After the reaction was completed, the mixture was washed three times by centrifugation with anhydrous ethanol and deionized water, and then dried at 60°C for 24 hours. The resulting product was the surface-modified silica / graphene oxide composite.

[0054] The coated and modified titanium dioxide was prepared by coating and modifying nano-titanium dioxide with sodium silicate.

[0055] The preparation method of the coated modified titanium dioxide is as follows:

[0056] Nano-titanium dioxide was dispersed in deionized water to prepare a suspension with a mass fraction of 1.5%. Then, 0.02 parts by weight of sodium hexametaphosphate were added to 100 parts by weight of the suspension. After ultrasonic dispersion, the suspension was heated to 80°C and 4 parts by weight of sodium silicate solution containing 26% silicon dioxide were added dropwise. The pH value was adjusted to 8 by adding 10% by weight of sulfuric acid solution. After aging at this temperature for 2 hours, the suspension was dried at 120°C for 12 hours. The resulting product is coated modified titanium dioxide.

[0057] Surface-fluorinated modified cellulose whiskers are obtained by surface modification of cellulose whiskers;

[0058] The preparation steps for surface-fluorinated modified cellulose whiskers are as follows:

[0059] Step 1: Weigh 5 parts by weight of microcrystalline cellulose and immerse it in a 54% sulfuric acid solution. Stir the solution with ultrasonic assistance and magnetic force at 52°C for 2 hours. After the reaction is completed, pour in a large amount of deionized water to terminate the reaction. Centrifuge to collect the precipitate and dialyze it to neutral. After freeze-drying, cellulose nanofibers are obtained.

[0060] Step II: Weigh 2 parts by weight of cellulose whiskers and pour them into 100 parts by weight of toluene. After stirring and dispersing, add 0.4 parts by weight of heptadecafluorodecyltrimethoxysilane. React at 70°C for 2 hours. Filter the reaction solution with a polyvinylidene fluoride membrane and wash it three times with toluene. Dry it at 45°C for 2 hours to obtain the surface-fluorinated modified cellulose whiskers.

[0061] A method for preparing a waterproof coating for building applications, the method comprising:

[0062] S1. Weigh 0.8 parts by weight of surface-modified silica / graphene oxide composite, 0.5 parts by weight of coated modified titanium dioxide, and 0.3 parts by weight of surface-fluorinated modified cellulose whiskers and pour them into 18 parts by weight of deionized water. Stir at 400 r / min for 10 min and then ultrasonically disperse at 300 W for 30 min. The result is recorded as the composite dispersion component.

[0063] S2. Add 100 parts by weight of epoxy resin / organosilicon composite modified waterborne polyurethane to a mixing tank, add 2 parts by weight of film-forming agent, and stir at 400 r / min for 20 min. Under the original stirring speed, add the composite dispersion component, followed by 0.1 parts by weight of defoamer and 0.1 parts by weight of leveling agent. After heating to 40℃, stir at 800 r / min for 45 min. Adjust the pH value to 7.5 with 1% ammonia water and 1% acetic acid solution, then cool to 25℃ and let stand for 2 hours. After filtration through a 200-mesh stainless steel screen, the resulting product is a waterproof coating for building applications.

[0064] Example 2

[0065] This embodiment provides a waterproof coating for building applications. The composition of the waterproof coating includes: epoxy resin / organosilicon composite modified waterborne polyurethane, surface modified silica / graphene oxide composite, coated modified titanium dioxide, surface fluorinated modified cellulose whiskers, film-forming agent, defoamer, and leveling agent.

[0066] The epoxy / silicone composite modified waterborne polyurethane is prepared using silicone-modified waterborne polyurethane prepolymer and epoxy resin as the main raw materials.

[0067] The preparation steps of silicone-modified waterborne polyurethane prepolymer are as follows:

[0068] Step A: Weigh 3 parts by weight of polypropylene glycol, 2 parts by weight of polycarbonate glycol, 4 parts by weight of amino silicone oil and 11 parts by weight of isoflurane diisocyanate and pour them into a flask. Stir at 500 r / min for 30 min, then heat to 70℃ and add 0.05 parts by weight of dibutyltin dilaurate. Keep the temperature for 2 h and then cool to 50℃. The result is recorded as the reaction component.

[0069] Step B: Add 1.5 parts by weight of 1,4-butanediol and 1 part by weight of 2,2-dimethylolpropionic acid to the reaction components. Add the calculated amount of acetone to adjust the viscosity to the preset value and keep it at the temperature for 5 minutes. Then raise the temperature to 70°C and keep it at the temperature for 2 hours. The result is the organosilicon-modified waterborne polyurethane prepolymer.

[0070] The preparation steps for epoxy resin / organic silicone composite modified waterborne polyurethane are as follows:

[0071] Add 7 parts by weight of epoxy resin to 100 parts by weight of silicone-modified waterborne polyurethane prepolymer, react at 70°C for 100 min, then cool to 50°C, add 3.5 parts by weight of triethylamine and keep reacting for 30 min, add 190 parts by weight of deionized water and stir at 1000 r / min for 30 min. The result is epoxy resin / silicone composite modified waterborne polyurethane.

[0072] The surface-modified silica / graphene oxide composite was prepared by coating graphene oxide with surface-modified silica.

[0073] The preparation steps for surface-modified silica are as follows:

[0074] Step 1: Weigh 4 parts by weight of nano-silica and disperse it in 100 parts by weight of anhydrous ethanol. After ultrasonic dispersion, the resulting solution is recorded as a suspension. Weigh 0.12 parts by weight of 3-aminopropyltriethoxysilane, 0.12 parts by weight of γ-glycidoxypropyltrimethoxysilane, and 0.12 parts by weight of γ-methacryloyloxypropyltrimethoxysilane and dissolve them in 20 parts by weight of anhydrous ethanol. After hydrolysis at room temperature for 30 minutes, the resulting solution is recorded as the hydrolysate.

[0075] Step 2: Pour the hydrolyzed components into the suspension and adjust the pH value to 5 with hydrochloric acid solution. Then heat to 75°C and stir magnetically for 6 hours. After cooling to room temperature, wash the components three times with anhydrous ethanol and deionized water. Dry the components at 60°C for 12 hours to obtain surface-modified silica.

[0076] The preparation method of surface-modified silica / graphene oxide composite is as follows:

[0077] 0.3 parts by weight of surface-modified silica were dispersed in 200 parts by weight of N,N-dimethylformamide and ultrasonically dispersed into a suspension. Then, 0.5 parts by weight of graphene oxide were added and ultrasonically dispersed again for 1 hour. The mixture was then placed in an oil bath at 105°C and reacted for 6 hours. After the reaction was completed, the mixture was washed three times by centrifugation with anhydrous ethanol and deionized water. The mixture was then dried at 60°C for 24 hours to obtain the surface-modified silica / graphene oxide composite.

[0078] The coated and modified titanium dioxide was prepared by coating and modifying nano-titanium dioxide with sodium silicate.

[0079] The preparation method of the coated modified titanium dioxide is as follows:

[0080] Nano-titanium dioxide was dispersed in deionized water to prepare a suspension with a mass fraction of 1.5%. Then, 0.05 parts by weight of sodium hexametaphosphate were added to 100 parts by weight of the suspension. After ultrasonic dispersion, the suspension was heated to 90°C and 5 parts by weight of sodium silicate solution containing 26% silicon dioxide were added dropwise. The pH value was adjusted to 10 by adding 10% by weight of sulfuric acid solution. After aging at this temperature for 2 hours, the suspension was dried at 120°C for 12 hours. The resulting product is coated modified titanium dioxide.

[0081] Surface-fluorinated modified cellulose whiskers are obtained by surface modification of cellulose whiskers;

[0082] The preparation steps for surface-fluorinated modified cellulose whiskers are as follows:

[0083] Step I: Weigh 6 parts by weight of microcrystalline cellulose and immerse it in a 54% sulfuric acid solution. Stir the solution with ultrasonic assistance and magnetic stirring at 52°C for 2 hours. After the reaction is completed, pour in a large amount of deionized water to terminate the reaction. Centrifuge to collect the precipitate and dialyze it to neutral. After freeze-drying, cellulose nanofibers are obtained.

[0084] Step II: Weigh 3 parts by weight of cellulose whiskers and pour them into 100 parts by weight of toluene. After stirring and dispersing, add 0.6 parts by weight of heptadecafluorodecyltrimethoxysilane. React at 70°C for 6 hours. Filter the reaction solution with a polyvinylidene fluoride membrane and wash it 5 times with toluene. Dry it at 45°C for 2 hours to obtain the surface-fluorinated modified cellulose whiskers.

[0085] A method for preparing a waterproof coating for building applications, the method comprising:

[0086] S1. Weigh 1.2 parts by weight of surface-modified silica / graphene oxide composite, 1 part by weight of coated modified titanium dioxide, and 0.6 parts by weight of surface-fluorinated modified cellulose whiskers and pour them into 20 parts by weight of deionized water. Stir at 500 r / min for 10 min and then ultrasonically disperse at 300 W for 30 min. The result is recorded as the composite dispersion component.

[0087] S2. Add 100 parts by weight of epoxy resin / organic silicone composite modified waterborne polyurethane to a mixing tank, add 4 parts by weight of film-forming agent, and stir at 600 r / min for 20 min. Under the original stirring speed, add the composite dispersion component, then add 0.3 parts by weight of defoamer and 0.2 parts by weight of leveling agent in sequence. After heating to 40℃, stir at 1000 r / min for 45 min. Adjust the pH value to 8.5 with 1% ammonia water and 1% acetic acid solution, then cool to 25℃, let stand and mature for 2 hours, and filter through a 200-mesh stainless steel screen. The result is a waterproof coating for building applications.

[0088] Example 3

[0089] This embodiment provides a waterproof coating for building applications. The composition of the waterproof coating includes: epoxy resin / organosilicon composite modified waterborne polyurethane, surface modified silica / graphene oxide composite, coated modified titanium dioxide, surface fluorinated modified cellulose whiskers, film-forming agent, defoamer, and leveling agent.

[0090] The epoxy / silicone composite modified waterborne polyurethane is prepared using silicone-modified waterborne polyurethane prepolymer and epoxy resin as the main raw materials.

[0091] The preparation steps of silicone-modified waterborne polyurethane prepolymer are as follows:

[0092] Step A: Weigh 2.8 parts by weight of polypropylene glycol, 1.8 parts by weight of polycarbonate glycol, 3.8 parts by weight of amino silicone oil and 10 parts by weight of isoflurane diisocyanate and pour them into a flask. Stir at 400 r / min for 30 min, then heat to 70℃ and add 0.04 parts by weight of dibutyltin dilaurate. Keep the temperature for 2 h and then cool to 50℃. The result is recorded as the reaction component.

[0093] Step B: Add 1.4 parts by weight of 1,4-butanediol and 0.8 parts by weight of 2,2-dimethylolpropionic acid to the reaction components. Add the calculated amount of acetone to adjust the viscosity to the preset value and keep it at the temperature for 5 minutes. Then raise the temperature to 70°C and keep it at the temperature for 2 hours. The result is the organosilicon-modified waterborne polyurethane prepolymer.

[0094] The preparation steps for epoxy resin / organic silicone composite modified waterborne polyurethane are as follows:

[0095] Add 6 parts by weight of epoxy resin to 100 parts by weight of silicone-modified waterborne polyurethane prepolymer, react at 70°C for 100 min, then cool to 50°C, add 3.2 parts by weight of triethylamine and keep reacting for 30 min, add 180 parts by weight of deionized water and stir at 900 r / min for 30 min. The result is epoxy resin / silicone composite modified waterborne polyurethane.

[0096] The surface-modified silica / graphene oxide composite was prepared by coating graphene oxide with surface-modified silica.

[0097] The preparation steps for surface-modified silica are as follows:

[0098] Step 1: Weigh 4 parts by weight of nano-silica and disperse it in 100 parts by weight of anhydrous ethanol. After ultrasonic dispersion, the resulting solution is called the suspension. Weigh 0.1 parts by weight of 3-aminopropyltriethoxysilane, 0.1 parts by weight of γ-glycidoxypropyltrimethoxysilane, and 0.1 parts by weight of γ-methacryloyloxypropyltrimethoxysilane and dissolve them in 20 parts by weight of anhydrous ethanol. After hydrolysis at room temperature for 30 minutes, the resulting solution is called the hydrolysate.

[0099] Step 2: Pour the hydrolyzed components into the suspension and adjust the pH value to 5 with hydrochloric acid solution. Then heat to 75°C and stir magnetically for 6 hours. After cooling to room temperature, wash the components three times with anhydrous ethanol and deionized water. Dry the components at 60°C for 12 hours to obtain surface-modified silica.

[0100] The preparation method of surface-modified silica / graphene oxide composite is as follows:

[0101] 0.3 parts by weight of surface-modified silica were dispersed in 200 parts by weight of N,N-dimethylformamide and ultrasonically dispersed into a suspension. Then, 0.4 parts by weight of graphene oxide were added and ultrasonically dispersed again for 1 hour. The mixture was then placed in an oil bath at 105°C and reacted for 6 hours. After the reaction was completed, the mixture was washed three times by centrifugation with anhydrous ethanol and deionized water. The mixture was then dried at 60°C for 24 hours to obtain the surface-modified silica / graphene oxide composite.

[0102] The coated and modified titanium dioxide was prepared by coating and modifying nano-titanium dioxide with sodium silicate.

[0103] The preparation method of the coated modified titanium dioxide is as follows:

[0104] Nano-titanium dioxide was dispersed in deionized water to prepare a suspension with a mass fraction of 1.5%. Then, 0.04 parts by weight of sodium hexametaphosphate were added to 100 parts by weight of the suspension. After ultrasonic dispersion, the suspension was heated to 85°C and 5 parts by weight of sodium silicate solution containing 26% silicon dioxide were added dropwise. The pH value was adjusted to 9 by adding 10% by weight of sulfuric acid solution. After aging at this temperature for 2 hours, the suspension was dried at 120°C for 12 hours. The resulting product is coated modified titanium dioxide.

[0105] Surface-fluorinated modified cellulose whiskers are obtained by surface modification of cellulose whiskers;

[0106] The preparation steps for surface-fluorinated modified cellulose whiskers are as follows:

[0107] Step I: Weigh 6 parts by weight of microcrystalline cellulose and immerse it in a 54% sulfuric acid solution. Stir the solution with ultrasonic assistance and magnetic stirring at 52°C for 2 hours. After the reaction is completed, pour in a large amount of deionized water to terminate the reaction. Centrifuge to collect the precipitate and dialyze it to neutral. After freeze-drying, cellulose nanofibers are obtained.

[0108] Step II: Weigh 3 parts by weight of cellulose whiskers and pour them into 100 parts by weight of toluene. After stirring and dispersing, add 0.5 parts by weight of heptadecafluorodecyltrimethoxysilane. React at 70°C for 4 hours. Filter the reaction solution with a polyvinylidene fluoride membrane and wash it 4 times with toluene. Dry it at 45°C for 2 hours to obtain the surface-fluorinated modified cellulose whiskers.

[0109] A method for preparing a waterproof coating for building applications, the method comprising:

[0110] S1. Weigh 1 part by weight of surface-modified silica / graphene oxide composite, 0.8 parts by weight of coated modified titanium dioxide, and 0.5 parts by weight of surface-fluorinated modified cellulose whiskers and pour them into 19 parts by weight of deionized water. Stir at 500 r / min for 10 min and then ultrasonically disperse at 300 W for 30 min. The result is recorded as the composite dispersion component.

[0111] S2. Add 100 parts by weight of epoxy resin / organic silicone composite modified waterborne polyurethane to a mixing tank, add 3 parts by weight of film-forming agent, and stir at 500 r / min for 20 min. Under the original stirring speed, add the composite dispersion component, followed by 0.2 parts by weight of defoamer and 0.2 parts by weight of leveling agent. After heating to 40℃, stir at 900 r / min for 45 min. Adjust the pH value to 8 with 1% ammonia water and 1% acetic acid solution, then cool to 25℃ and let stand for 2 hours. After filtration through a 200-mesh stainless steel screen, the resulting product is a waterproof coating for building applications.

[0112] Comparative Example 1

[0113] The waterproof coating for building and its preparation method provided in this comparative example are generally the same as those in Example 1, except that the epoxy resin / organosilicon composite modified waterborne polyurethane in Example 1 is replaced with waterborne polyurethane.

[0114] Comparative Example 2

[0115] The waterproof coating for building and its preparation method provided in this comparative example are generally the same as those in Example 1. The main difference is that the surface-modified silica / graphene oxide composite in Example 1 is replaced with coated modified titanium dioxide in this comparative example.

[0116] Comparative Example 3

[0117] The waterproof coating for building and its preparation method provided in this comparative example are generally the same as those in Example 1. The main difference is that the surface fluorinated modified cellulose whiskers in Example 1 are replaced with surface modified silica / graphene oxide composites in this comparative example.

[0118] Performance testing

[0119] The waterproof coatings for building use prepared in Examples 1-3 and Comparative Examples 1-3 were labeled as Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3, respectively. The performance of Examples 1-3 and Comparative Examples 1-3 was then tested. The specific testing methods and items are as follows:

[0120] 1. The waterproof coatings for building use prepared in Examples 1-3 and Comparative Examples 1-3 were applied as coatings, and then their contact angles were measured. The data obtained are recorded in Table 1.

[0121] 2. The tensile properties of the polymer-based cement waterproof coatings of Examples 1-3 and Comparative Examples 1-3 were tested according to GB / T16777-2008 "Test Methods for Waterproof Coatings for Buildings". The data obtained are recorded in Table 1.

[0122] 3. Friction and wear tests were conducted on the polymer-based cement waterproof coatings of Examples 1-3 and Comparative Examples 1-5 using an MFT-5000 friction and wear testing machine. The reciprocating distance was 4 mm, the operating frequency was 200 times / min, the rated load was 2.2 N, and the test time was 30 min. The wear amount was calculated, and the obtained wear rate data are recorded in Table 1.

[0123] The data in the table above shows that the waterproof coatings for buildings prepared in Examples 1-3 have superior waterproof and mechanical properties compared to Comparative Examples 1-3. This indicates that the waterproof coatings for buildings prepared in this invention using epoxy resin / organosilicon composite modified waterborne polyurethane, surface-modified silica / graphene oxide composite, coated modified titanium dioxide, and surface-fluorinated modified cellulose whiskers as main raw materials can enable the components to work synergistically to produce coatings with better performance.

[0124] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0125] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A waterproof coating for building applications, characterized in that, The composition of the waterproof coating for building applications includes: epoxy resin / organosilicon composite modified waterborne polyurethane, surface modified silica / graphene oxide composite, coated modified titanium dioxide, surface fluorinated modified cellulose whiskers, film-forming agent, defoamer and leveling agent. The epoxy resin / organosilicon composite modified waterborne polyurethane is prepared using organosilicon modified waterborne polyurethane prepolymer and epoxy resin as the main raw materials. The surface-modified silica / graphene oxide composite was prepared by coating graphene oxide with surface-modified silica. The coated and modified titanium dioxide is prepared by coating and modifying nano-titanium dioxide with sodium silicate. The surface-fluorinated modified cellulose whiskers are obtained by surface modification of cellulose whiskers.

2. The waterproof coating for building applications according to claim 1, characterized in that, The preparation steps of the organosilicon-modified waterborne polyurethane prepolymer are as follows: Step A: Weigh 2.4-3 parts by weight of polypropylene glycol, 1.6-2 parts by weight of polycarbonate glycol, 3.5-4 parts by weight of amino silicone oil and 9-11 parts by weight of isoflurone diisocyanate and pour them into a flask. After stirring and mixing, heat to 70°C and add 0.04-0.05 parts by weight of dibutyltin dilaurate. Keep the temperature for 2 hours and then cool to 50°C. The result is recorded as the reaction component. Step B: Add 1.2-1.5 parts by weight of 1,4-butanediol and 0.7-1 parts by weight of 2,2-dimethylolpropionic acid to the reaction components. Add the calculated amount of acetone to adjust the viscosity to the preset value and keep it at the temperature for 5 minutes. Then raise the temperature to 70°C and keep it at the temperature for 2 hours. The result is the organosilicon-modified waterborne polyurethane prepolymer.

3. The waterproof coating for building applications according to claim 2, characterized in that, The mixing method in step A is to stir at a stirring speed of 300-500 r / min for 30 min.

4. The waterproof coating for building applications according to claim 1, characterized in that, The preparation steps of the epoxy resin / organosilicon composite modified waterborne polyurethane are as follows: Add 5-7 parts by weight of epoxy resin to 100 parts by weight of silicone-modified waterborne polyurethane prepolymer, react at 70°C for 100 min, then cool to 50°C, add 3-3.5 parts by weight of triethylamine and keep reacting at 70°C for 30 min, then add 170-190 parts by weight of deionized water and stir at 800-1000 r / min for 30 min. The result is epoxy resin / silicone composite modified waterborne polyurethane.

5. A waterproof coating for building applications according to claim 1, characterized in that, The preparation steps of the surface-modified silica are as follows: Step 1: Weigh 3-4 parts by weight of nano-silica and disperse it in 100 parts by weight of anhydrous ethanol. After ultrasonic dispersion, the resulting solution is recorded as a suspension. Weigh 0.08-0.12 parts by weight of 3-aminopropyltriethoxysilane, 0.08-0.12 parts by weight of γ-glycidoxypropyltrimethoxysilane, and 0.08-0.12 parts by weight of γ-methacryloyloxypropyltrimethoxysilane and dissolve them in 20 parts by weight of anhydrous ethanol. After hydrolysis at room temperature for 30 minutes, the resulting solution is recorded as the hydrolysate. Step 2: Pour the hydrolyzed components into the suspension and adjust the pH value to 4-5 with hydrochloric acid solution. Then heat to 75℃ and stir magnetically for 6 hours. After cooling to room temperature, wash with anhydrous ethanol and deionized water three times in sequence by centrifugation. Dry at 60℃ for 12 hours to obtain surface-modified silica.

6. A waterproof coating for building applications according to claim 1, characterized in that, The preparation method of the surface-modified silica / graphene oxide composite is as follows: Weigh 0.2-0.3 parts by weight of surface-modified silica and disperse it in 200 parts by weight of N,N-dimethylformamide. After ultrasonic dispersion into a suspension, add 0.3-0.5 parts by weight of graphene oxide and ultrasonically disperse again for 1 hour. Then, react in an oil bath at 105°C for 6 hours. After the reaction is complete, wash the silica / graphene oxide composite by centrifugation three times with anhydrous ethanol and deionized water, and dry it at 60°C for 24 hours.

7. A waterproof coating for building applications according to claim 1, characterized in that, The preparation method of the coated modified titanium dioxide is as follows: Nano-titanium dioxide was dispersed in deionized water to prepare a suspension with a mass fraction of 1.5%. Then, 0.02-0.05 parts by weight of sodium hexametaphosphate were added to 100 parts by weight of the suspension. After ultrasonic dispersion, the suspension was heated to 80-90℃ and 4-5 parts by weight of sodium silicate solution containing 26% silicon dioxide were added dropwise. The pH value was adjusted to 8-10 by adding 10% by weight of sulfuric acid solution. After aging at this temperature for 2 hours, the suspension was dried at 120℃ for 12 hours. The resulting product is coated modified titanium dioxide.

8. A waterproof coating for building applications according to claim 1, characterized in that, The preparation steps of the surface-fluorinated modified cellulose whiskers are as follows: step Weigh 5-6 parts by weight of microcrystalline cellulose and immerse it in a 54% sulfuric acid solution. Stir the solution with ultrasonic assistance and magnetic stirring at 52°C for 2 hours. After the reaction is completed, pour in a large amount of deionized water to terminate the reaction. Centrifuge to collect the precipitate and dialyze it to neutral. After freeze-drying, cellulose nanofibers are obtained. step Weigh 2-3 parts by weight of cellulose whiskers and pour them into 100 parts by weight of toluene. After stirring and dispersing, add 0.4-0.6 parts by weight of heptadecafluorodecyltrimethoxysilane. React at 70°C for 2-6 hours. Filter the reaction solution with a polyvinylidene fluoride membrane and wash it with toluene 3-5 times. Dry it at 45°C for 2 hours to obtain the surface-fluorinated modified cellulose whiskers.

9. A method for preparing a waterproof coating for building applications according to any one of claims 1-8, characterized in that, The preparation method is as follows: S1. Weigh 0.8-1.2 parts by weight of surface-modified silica / graphene oxide composite, 0.5-1 parts by weight of coated modified titanium dioxide, and 0.3-0.6 parts by weight of surface-fluorinated modified cellulose whiskers and pour them into 18-20 parts by weight of deionized water. The result after dispersion treatment is recorded as the composite dispersion component. S2. Add 100 parts by weight of epoxy resin / organosilicon composite modified waterborne polyurethane to a mixing tank, add 2-4 parts by weight of film-forming agent and stir to disperse. Add the composite dispersion components under the original stirring speed, then add 0.1-0.3 parts by weight of defoamer and 0.1-0.2 parts by weight of leveling agent in sequence. Heat to 40℃ and stir at 800-1000 r / min for 45 min. Adjust the pH value to 7.5-8.5 and then cool to 25℃. After standing and curing for 2 hours, filter through a 200-mesh stainless steel screen. The result is a waterproof coating for building applications.

10. A method for preparing a waterproof coating for building applications according to claim 9, characterized in that, The dispersion method in S1 is to first stir at a stirring speed of 400-500 r / min for 10 min, and then ultrasonically disperse at a power of 300 W for 30 min. The stirring and dispersion method in S2 is to stir at a stirring speed of 400-600 r / min for 20 min. In S2, the pH value is adjusted with a 1% ammonia solution and a 1% acetic acid solution.

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