Root-resistant polyurethane waterproof coating

Abstract

The invention relates to the technical field of building waterproof coatings, and discloses a root-resistant polyurethane waterproof coating which comprises the following components in percentage by weight: 70%-80% of a polyurethane prepolymer, 5%-10% of a root-resistant additive, 5%-10% of filler, 5%-10% of a solvent, 1%-3% of a hindered amine light stabilizer, 0.5%-1.5% of an antioxidant, 0.5%-2% of a silane coupling agent, 0.5%-2% of a rheological additive and 0.1%-0.5% of nano-silver particles. Plant root systems can be effectively prevented from penetrating through the waterproof layer through component synergy; aging can be inhibited, oxidative deterioration is prevented, and the service life is prolonged; the hardness and the wear resistance are improved, and the cost is reduced; the coating flowability and the coating uniformity are guaranteed, sagging is avoided, the overall stability is improved, and the product quality is guaranteed. The problems that a traditional polyurethane waterproof coating is prone to damage and poor in waterproofness and durability when puncturing the root system of a plant are solved.

Description

Technical Field

[0001] The invention relates to the technical field of building waterproof coatings, in particular to a root-barrier polyurethane waterproof coating. Background Art

[0002] In modern urban construction, the concept of green building is gaining widespread popularity, with projects such as planted roofs, roof gardens, and greening of underground parking roofs constantly emerging. These architectural scenarios place stringent demands on waterproofing materials, requiring them to not only provide reliable waterproofing to prevent water seepage and damage to the building structure, but also possess excellent root barrier properties to effectively resist puncture and damage from plant roots.

[0003] While traditional polyurethane waterproof coatings have found some application in the waterproofing field, they exhibit significant drawbacks when it comes to plant roots. For one thing, plant roots generate significant pressure during their growth, which the structure of traditional polyurethane waterproof coatings cannot withstand, leading to physical damage and failure of the waterproof layer. Furthermore, under the long-term influence of the natural environment, traditional coatings may biodegrade, further weakening their waterproofing and root barrier capabilities. Furthermore, conventional polyurethane waterproof coatings also have deficiencies in weather resistance, adhesion, and rheological properties, making them unable to meet the complex and changing outdoor use environments and diverse construction requirements, seriously affecting the quality and service life of building waterproofing projects. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a root-blocking polyurethane waterproof coating, which solves the problems of traditional polyurethane waterproof coatings being easily damaged when facing plant root puncture and having poor waterproofness and durability.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: a root-blocking polyurethane waterproof coating, which comprises the following ingredients, by weight percentage: 70%-80% polyurethane prepolymer, 5%-10% root-blocking additive, 5%-10% filler, 5%-10% solvent, 1%-3% hindered amine light stabilizer, 0.5%-1.5% antioxidant, 0.5%-2% silane coupling agent, 0.5%-2% rheological additive, and 0.1%-0.5% nanosilver particles.

[0006] Preferably, the polyurethane prepolymer is prepared by reacting a polyether polyol and an isocyanate monomer in the presence of a catalyst, the molecular weight of the polyether polyol is in the range of 2000-4000, the isocyanate monomer includes one or more of aliphatic isocyanate and aromatic isocyanate, and the catalyst is dibutyltin dilaurate, and its amount is 0.05%-0.1% of the total mass of the reactants.

[0007] Preferably, the root-blocking additive is sodium bentonite, the montmorillonite content of the sodium bentonite is not less than 80%, the cation exchange capacity is between 80-120 mmol / 100 g, and it has been organically modified, the modifier is organic silane and organic quaternary ammonium salt, the mass ratio of the two is 1:(1-3), and the total amount of the modifier is 15%-25% of the mass of the sodium bentonite.

[0008] Preferably, the filler is a mixture of fine-grained quartz sand and kaolin, the particle size of the fine-grained quartz sand is 10-50 μm, the particle size of the kaolin is 2-10 μm, and the mass ratio of the fine-grained quartz sand to the kaolin is (2-4):1.

[0009] Preferably, the solvent is a mixed solvent of ethyl acetate and propylene glycol methyl ether acetate, and the volume ratio of ethyl acetate to propylene glycol methyl ether acetate is (1-3):1.

[0010] Preferably, the hindered amine light stabilizer is sebacic acid diester, and the number of piperidine rings in the molecular structure is not less than 2.

[0011] Preferably, the antioxidant is a compound of a phenolic antioxidant and a phosphite antioxidant, the phenolic antioxidant is antioxidant 1010, and the phosphite antioxidant is triester phosphite, and the mass ratio of the two is (1-2):1.

[0012] Preferably, the silane coupling agent is one or more of γ-methacryloxypropyltrimethoxysilane and γ-aminopropyltrimethoxysilane, and its molecular structure contains a hydrolyzable methoxy group or ethoxy group and an organic functional group capable of reacting with the polyurethane prepolymer.

[0013] Preferably, the rheological additive is fumed silica with a specific surface area of ​​150-300 m 2 / g, and regulates the rheological properties of the coating by forming a hydrogen bond network structure in the coating system.

[0014] A method for preparing a root-barrier polyurethane waterproof coating, used for the root-barrier polyurethane waterproof coating, the method comprising the following steps: S1. Add the polyurethane prepolymer to a high-speed stirring device and stir at a speed of 5000-7000 r / min. At the same time, add the solvent and stir for 5-10 minutes; S2. Add root inhibitor additive, filler, hindered amine light stabilizer, antioxidant, silane coupling agent, rheological additive, and nanosilver particles in sequence, and continue stirring for 10-15 minutes; S3. Transfer the mixture to an ultrasonic dispersion device and ultrasonically disperse it for 15-20 minutes at a frequency of 25-35 kHz and a power of 150-250 W; S4. Finally, the mixture is stirred and matured at a low speed with a stirring speed of 300-500 r / min, the temperature is controlled at 40-50° C., and the stirring time is 10-15 minutes to obtain the root-blocking polyurethane waterproof coating.

[0015] The present invention provides a root-blocking polyurethane waterproof coating having the following beneficial effects: 1. The present invention, through the synergistic combination of ingredients, effectively prevents plant roots from penetrating the waterproof layer; inhibits aging, prevents oxidative deterioration, and extends service life; improves hardness and wear resistance while reducing costs; ensures coating fluidity and uniformity, prevents sagging, improves overall stability, and guarantees product quality. This addresses the issues of traditional polyurethane waterproof coatings, such as their vulnerability to plant root penetration and poor waterproofness and durability.

[0016] 2. The polyurethane prepolymer produced in the present invention exhibits excellent reactivity and film-forming properties, resulting in a coating with suitable flexibility, strength, and chemical resistance. It effectively serves as a base film-forming substance in waterproof coatings, ensuring the coating possesses excellent waterproofing and physical and mechanical properties. This addresses the problem of poor film performance in waterproof coatings produced during conventional polyurethane prepolymer preparation.

[0017] 3. The modified sodium bentonite in this invention effectively bonds with the polyurethane prepolymer in the root-blocking polyurethane waterproof coating, forming a denser microstructure. When encountering plant roots, its unique structure and enhanced properties after modification effectively physically block root penetration. It also alters the microenvironment surrounding the roots, inhibiting root growth and significantly improving the coating's root barrier properties. This addresses the issue of poor root barrier effectiveness associated with traditional root-blocking additives.

[0018] 4. The present invention utilizes a coating with good fluidity to facilitate uniform coating, forming a uniform, smooth coating film. A reasonable volatilization rate prevents defects such as sagging and wrinkling in the coating film, ensuring the coating's appearance quality. Furthermore, good solubility allows the coating components to be fully dissolved and dispersed, improving the coating's stability and preventing precipitation and delamination. This solves the problem of insufficient solubility preventing the coating components from being fully dissolved.

[0019] 5. The present invention improves the coating's antioxidant capacity during storage and use, effectively slowing the coating's oxidative deterioration rate and maintaining its chemical stability. This allows the coating's performance indicators, such as viscosity and film-forming properties, to remain stable for an extended period, avoiding issues such as discoloration, thickening, and decreased film performance caused by oxidation, thereby extending the coating's effective service life. This addresses the limited inhibitory effect of a single antioxidant on the complex oxidation process of a coating.

[0020] 6. In the present invention, by adjusting the rheological properties of the coating, good construction operability is ensured during the application process, making it easy to apply and forming a coating film of uniform thickness. The coating is also ensured to quickly set after application, avoiding problems such as sagging and accumulation that affect the appearance and quality of the coating film. At the same time, the stability of the coating during storage is improved, preventing phenomena such as precipitation and delamination that affect the performance of the coating. The problem of poor rheological properties of the coating is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of the preparation method of a root-blocking polyurethane waterproof coating proposed by the present invention. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0023] Please see the attached Figure 1 An embodiment of the present invention provides a root-blocking polyurethane waterproof coating, which comprises the following ingredients, by weight percentage: 70%-80% polyurethane prepolymer, 5%-10% root-blocking additive, 5%-10% filler, 5%-10% solvent, 1%-3% hindered amine light stabilizer, 0.5%-1.5% antioxidant, 0.5%-2% silane coupling agent, 0.5%-2% rheological additive, and 0.1%-0.5% nano-silver particles.

[0024] Specifically, by adding a polyurethane prepolymer at a ratio of 70%-80%, the main component of the waterproof coating's base film-forming material is obtained. The polyurethane prepolymer has excellent reactivity and film-forming properties. During the subsequent curing process, it forms a continuous, tough polymer film, providing the waterproof coating with essential waterproof and physical properties.

[0025] By adding 5% to 10% of a root barrier additive, a key component is created that prevents plant roots from penetrating the coating. This additive effectively disrupts the growth path of plant roots, preventing them from penetrating the waterproof layer and ultimately imparting excellent root barrier properties to the coating.

[0026] By adding 5%-10% filler to the system, we obtain an auxiliary component that can enhance the overall performance of the coating. Fillers can increase the hardness and wear resistance of the coating, improve the coating's workability, and enhance the waterproof coating's applicability in actual use and construction.

[0027] By using 5% to 10% solvent, a medium is created that can dissolve and disperse the other ingredients. The solvent allows the ingredients to mix evenly, reducing the viscosity of the coating, ensuring that the waterproof coating has good fluidity and coating properties during application.

[0028] By adding 1% to 3% of a hindered amine light stabilizer, a key additive that inhibits photooxidative degradation of the coating is obtained. The hindered amine light stabilizer can capture free radicals generated by light, thereby enhancing the waterproof coating's aging resistance in light-exposed environments.

[0029] By adding 0.5% to 1.5% of an antioxidant, a protective component is created to prevent the coating from oxidizing. The antioxidant preferentially reacts with the peroxides produced during oxidation, blocking the generation of free radicals and improving the stability of the waterproof coating during storage and use.

[0030] By adding 0.5% to 2% of a silane coupling agent, an additive that improves the coating's interfacial properties is obtained. Silane coupling agents can form chemical bonds between inorganic components and the polymer matrix, strengthening the bonding between the coating's components and improving overall performance.

[0031] By using 0.5% to 2% of a rheological additive, a substance that modifies the coating's rheological properties is obtained. The rheological additive modifies the coating's flow and deformation behavior, preventing sagging during application and ensuring a uniform coating film thickness.

[0032] By adding 0.1% to 0.5% nanosilver particles, a component with enhanced root barrier and antibacterial properties is obtained. Nanosilver particles can inhibit the growth of microorganisms that coexist with plant roots, indirectly enhancing the root barrier effect and further improving the root barrier performance of waterproof coatings.

[0033] Through the synergistic effect of its various components, it possesses excellent root barrier properties, effectively preventing plant roots from penetrating the waterproof layer. Its excellent weather resistance and antioxidant properties inhibit aging, prevent oxidative deterioration, and extend its service life. It also enhances internal structural stability, improves hardness and abrasion resistance, and reduces costs. It also improves application performance, ensuring coating fluidity and uniformity, and preventing sagging. Furthermore, the excellent compatibility of its various components enhances overall stability and ensures product quality. This addresses the issues of traditional polyurethane waterproof coatings, such as their vulnerability to plant root penetration and their poor waterproofness and durability.

[0034] The polyurethane prepolymer is prepared by reacting polyether polyol and isocyanate monomer in the presence of a catalyst. The molecular weight of the polyether polyol is in the range of 2000-4000. The isocyanate monomer includes one or more of aliphatic isocyanate and aromatic isocyanate. The catalyst is dibutyltin dilaurate, and its usage is 0.05%-0.1% of the total mass of the reactants.

[0035] Specifically, the hydroxyl groups in the polyether polyol molecules react continuously with the isocyanate groups in the isocyanate monomers to form a polyurethane prepolymer containing urethane bonds. Because the molecular weight of the polyether polyol is between 2000 and 4000, the resulting polyurethane prepolymer can be controlled to have an appropriate molecular chain length and molecular weight distribution. The choice of aliphatic or aromatic isocyanates can impart different performance characteristics to the polyurethane prepolymer. For example, aliphatic isocyanates can impart better weather resistance to the prepolymer, while aromatic isocyanates can increase the hardness and strength of the prepolymer. The catalyst, dibutyltin dilaurate, is controlled at 0.05% to 0.1% of the total mass of the reactants to precisely adjust the reaction rate and avoid overly rapid or slow reactions.

[0036] The resulting polyurethane prepolymer exhibits excellent reactivity and film-forming properties, resulting in a coating with suitable flexibility, strength, and chemical resistance. It effectively serves as a base film-forming substance in waterproof coatings, ensuring excellent waterproofing and physical and mechanical properties. This addresses the poor film properties of waterproof coatings typically encountered during the traditional polyurethane prepolymer preparation process.

[0037] The root-blocking additive is sodium bentonite, the montmorillonite content of the sodium bentonite is not less than 80%, the cation exchange capacity is between 80-120 mmol / 100 g, and it has been organically modified. The modifier is organic silane and organic quaternary ammonium salt, and the mass ratio of the two is 1: (1-3). The total amount of the modifier is 15%-25% of the mass of the sodium bentonite.

[0038] Specifically, the sodium bentonite contains no less than 80% montmorillonite. Montmorillonite has a unique layered structure that can accommodate cations between its layers, with a cation exchange capacity of 80-120 mmol / 100g. This gives it a certain degree of adsorption and swelling properties. A modifier is composed of an organosilane and an organic quaternary ammonium salt in a mass ratio of 1:1-3, and is used in an amount of 15%-25% of the mass of the sodium bentonite. The organosilane, through its silicon-oxygen bonds, undergoes a condensation reaction with the hydroxyl groups on the bentonite surface, forming an organosilane film on the bentonite surface, enhancing its compatibility with organic polymers. The organic quaternary ammonium salt, with its long-chain alkyl structure, inserts into the interlayers of the bentonite, increasing the interlayer spacing and simultaneously changing the hydrophilicity and hydrophobicity of the bentonite surface.

[0039] Modified sodium bentonite in root-blocking polyurethane waterproof coatings can better bond with the polyurethane prepolymer, forming a denser microstructure. When encountering plant roots, its unique structure and enhanced properties after modification effectively physically block root penetration. It also alters the microenvironment surrounding the roots, inhibiting root growth and significantly improving the coating's root barrier properties. This addresses the issue of poor root barrier effectiveness associated with traditional root-blocking additives.

[0040] The filler is a mixture of fine-grained quartz sand and kaolin. The particle size of the fine-grained quartz sand is 10-50 μm, the particle size of the kaolin is 2-10 μm, and the mass ratio of the fine-grained quartz sand to the kaolin is (2-4):1.

[0041] Specifically, fine-grained quartz sand has a particle size of 10-50μm, high hardness, and stable chemical properties; kaolin has a particle size of 2-10μm, exhibiting good plasticity and adhesion. When the two are mixed in a mass ratio of (2-4):1, they are uniformly dispersed throughout the coating. The fine-grained quartz sand, leveraging its hardness, fills the coating film, strengthening its skeletal structure and improving its abrasion and impact resistance. Kaolin, leveraging its plasticity and adhesion, fills the gaps between the quartz sand particles, making the coating system more compact and enhancing its adhesion to other ingredients.

[0042] By enhancing the coating's physical properties, the film becomes stronger and more durable, resisting wear and tear over long-term use. It also improves the coating's application properties, making it smoother and easier to apply evenly. It also enhances the film's waterproof properties, with a dense structure that effectively prevents water penetration. This overcomes the problem of traditional coatings, which suffer from poor wear resistance and susceptibility to external damage.

[0043] The solvent is a mixed solvent of ethyl acetate and propylene glycol methyl ether acetate, and the volume ratio of ethyl acetate to propylene glycol methyl ether acetate is (1-3):1.

[0044] Specifically, ethyl acetate has a relatively fast volatilization rate, allowing it to evaporate quickly after coating application, allowing the coating to dry quickly. Propylene glycol methyl ether acetate has a relatively slow volatilization rate, ensuring sufficient open time during coating application, facilitating handling. It also dissolves more resin and additives, improving coating stability. In a mixed solvent system, the two work together to control the overall solvent volatilization rate.

[0045] The coating's excellent fluidity facilitates uniform application, resulting in a smooth, even film. A reasonable evaporation rate prevents defects such as sagging and wrinkling, ensuring a high-quality coating. Furthermore, its excellent solubility allows for full dissolution and dispersion of all coating components, improving coating stability and preventing precipitation and delamination. This solves the problem of insufficient solubility preventing the full dissolution of coating components.

[0046] The hindered amine light stabilizer is a diester of sebacic acid, and the number of piperidine rings in the molecular structure is not less than 2.

[0047] Specifically, when the coating is exposed to light, the nitrogen atoms on the piperidine ring can capture the free radicals generated by the light. These free radicals are the key factor in the coating's photooxidative degradation reaction. When a light stabilizer is present, its chemical structure, through reaction mechanisms such as hydrogen atom transfer, deactivates the free radicals, thereby interrupting the chain reaction of photooxidative degradation and preventing the reaction from continuing.

[0048] By inhibiting the aging of the paint under light conditions, the physical properties of the paint film, such as its strength, flexibility, and adhesion, are maintained. This allows the paint to maintain good integrity under long-term light exposure, making it less susceptible to problems such as powdering, cracking, and discoloration caused by light aging, thereby extending the paint's service life. This solves the problem of traditional paints rapidly aging and degrading due to light.

[0049] The antioxidant is a compound of a phenolic antioxidant and a phosphite antioxidant, the phenolic antioxidant is antioxidant 1010, and the phosphite antioxidant is triester phosphite, and the mass ratio of the two is (1-2):1.

[0050] Specifically, Antioxidant 1010's molecular structure contains multiple active phenolic hydroxyl groups capable of donating hydrogen atoms. When a coating system faces an oxidizing environment, these phenolic hydroxyl groups are the first to react with the peroxide free radicals generated during the oxidation process, becoming oxidized into relatively stable phenoxy free radicals. This blocks the further propagation of the free radical chain reaction and inhibits oxidation. Phosphite antioxidants, on the other hand, primarily react with the hydroperoxides produced by oxidation in the coating through their own phosphorus atoms, decomposing the hydroperoxides into relatively harmless alcohols and phosphates. This reduces the content of highly oxidizing substances in the system and further prevents the continued oxidation reaction. The two antioxidants work synergistically to inhibit the oxidation process in the coating system through different reaction pathways.

[0051] By improving the coating's antioxidant capacity during storage and use, it effectively slows down the coating's oxidative deterioration, maintains the coating's chemical stability, and enables the coating's performance indicators, such as viscosity and film-forming properties, to remain stable for an extended period of time. This prevents problems such as discoloration, thickening, and decreased film performance caused by oxidation, thereby extending the coating's effective service life. This solves the problem of a single antioxidant's limited inhibitory effect on the complex oxidation process of coatings.

[0052] The silane coupling agent is one or more of gamma-methacryloxypropyltrimethoxysilane and gamma-aminopropyltrimethoxysilane, and its molecular structure contains a hydrolyzable methoxy group or ethoxy group and an organic functional group capable of reacting with the polyurethane prepolymer.

[0053] Specifically, in the coating system, the methoxy or ethoxy groups first undergo hydrolysis in the presence of moisture to generate silanol groups. These silanol groups can, on the one hand, undergo a condensation reaction with the hydroxyl groups on the surface of the inorganic filler (such as quartz sand) in the coating, forming chemical bonds on the surface of the inorganic filler, thereby modifying the surface of the inorganic filler, making its surface properties more similar to those of the organic phase and improving the compatibility between the inorganic filler and the organic polymer. On the other hand, the organic functional groups (such as methacryloyloxy and amino groups) in the silane coupling agent molecules can chemically react with the active groups (such as isocyanate groups) in the polyurethane prepolymer, building a chemical bond bridge between the polyurethane prepolymer and the inorganic filler, tightly combining the two.

[0054] By enhancing the interfacial bonding between the inorganic filler and the polyurethane prepolymer in the coating, the compatibility between the various components is significantly improved, resulting in a more stable and uniform coating system. After film formation, the coating's cohesion is enhanced, effectively preventing delamination and shedding that can occur due to a loose bond between the inorganic filler and the polymer matrix. This also improves the coating's overall mechanical properties, such as hardness, flexibility, and adhesion. This addresses the poor compatibility between inorganic fillers and organic polymers in traditional coatings.

[0055] The rheological additive is fumed silica with a specific surface area of ​​150-300m 2 / g, and regulates the rheological properties of the coating by forming a hydrogen bond network structure in the coating system.

[0056] Specifically, there are a large number of silanol groups on the surface of fumed silica. These silanol groups can interact with active groups such as hydroxyl groups on the surfaces of solvent molecules, polymer molecules and other components in the coating system through hydrogen bonds, thereby forming a three-dimensional hydrogen bond network structure in the coating system. When the coating is in a static state, this hydrogen bond network structure makes the coating exhibit a higher viscosity and has a certain anti-sagging ability, which can effectively prevent the coating from flowing or sagging due to its own gravity when it is applied on a vertical or inclined surface. When external force is applied for construction operations such as stirring and brushing, the hydrogen bond network structure will be temporarily destroyed, the viscosity of the coating will decrease, and the fluidity will improve, making it easier to evenly apply to the construction surface. When the external force is removed, the hydrogen bond network structure will gradually recover, and the viscosity of the coating will increase again, returning to a state where it can maintain its shape.

[0057] By adjusting the rheological properties of the coating, good construction operability is ensured during application, making it easy to apply and forming a coating film of uniform thickness. It also ensures that the coating sets quickly after application, avoiding problems such as sagging and accumulation that affect the appearance and quality of the coating film. It also improves the stability of the coating during storage, preventing precipitation and stratification that affect the coating's performance. This solves the problem of poor rheological properties of the coating.

[0058] Please see the attached Figure 1 A method for preparing a root-barrier polyurethane waterproof coating, for a root-barrier polyurethane waterproof coating, the method comprising the following steps: S1. Add the polyurethane prepolymer to a high-speed stirring device and stir at a speed of 5000-7000 r / min. At the same time, add the solvent and stir for 5-10 minutes; S2. Add root inhibitor additive, filler, hindered amine light stabilizer, antioxidant, silane coupling agent, rheological additive, and nanosilver particles in sequence, and continue stirring for 10-15 minutes; S3. Transfer the mixture to an ultrasonic dispersion device and ultrasonically disperse it for 15-20 minutes at a frequency of 25-35 kHz and a power of 150-250 W; S4. Finally, the mixture is stirred and matured at a low speed with a stirring speed of 300-500 r / min, the temperature is controlled at 40-50° C., and the stirring time is 10-15 minutes to obtain a root-blocking polyurethane waterproof coating.

[0059] Specifically, in step S1, the polyurethane prepolymer is added to a high-speed stirring device, stirred at a speed of 5000-7000 r / min, and a solvent is added at the same time. The high-speed stirring can generate a strong shear force, so that the polyurethane prepolymer is quickly dispersed in the solvent. The solvent molecules fully wrap the polyurethane prepolymer molecules, reducing the viscosity of the system, allowing the various parts to be initially evenly mixed to avoid agglomeration, laying a good foundation for the subsequent addition of other components.

[0060] The working principle is to sequentially add a root inhibitor additive, filler, hindered amine light stabilizer, antioxidant, silane coupling agent, rheological additive, and nano-silver particles through step S2, and then continue stirring for 10-15 minutes. The mechanical force generated by continuous stirring causes the newly added components to continuously collide and diffuse in the existing polyurethane prepolymer and solvent mixture system, so that they are evenly distributed throughout the system. The components can fully contact each other, creating conditions for possible subsequent interactions, such as better chemical bonding reactions between the silane coupling agent and the inorganic filler and the polyurethane prepolymer.

[0061] The mixture is transferred to an ultrasonic dispersion device through step S3 and ultrasonically dispersed for 15-20 minutes at a frequency of 25-35 kHz and a power of 150-250 W. The high-frequency vibration and cavitation generated during the ultrasonic dispersion process can break up agglomerates at the microscopic level, allowing particles that are difficult to further refine and disperse through mechanical stirring to be further evenly dispersed. At the same time, it enhances the interaction between the components, such as allowing the filler to be more tightly bonded to the polymer matrix, further improving the uniformity and stability of the coating system.

[0062] The step S4 is finally followed by low-speed stirring and aging under stirring, with a stirring speed of 300-500 r / min, a temperature controlled at 40-50°C, and a stirring time of 10-15 minutes. Under suitable temperature and low-speed stirring conditions, the chemical reactions between the components in the coating system can proceed more fully and smoothly, such as further cross-linking and curing of the polyurethane prepolymer, and continuous improvement of the interaction between the additives and the matrix, so that the coating system gradually stabilizes and forms a stable structure and performance state.

[0063] High-speed stirring is used to fully blend the polyurethane prepolymer and solvent, followed by the sequential addition of each component with continuous stirring to ensure uniform dispersion. Ultrasonic dispersion is then used to further refine the microstructure and enhance synergy. Finally, low-speed stirring and aging are used to optimize the performance of the coating system. This overall process achieves uniform dispersion of the coating components, avoids local performance differences, improves the uniformity and stability of the coating's overall performance, and optimizes film quality, waterproofing, root barrier properties, and durability. It solves many problems caused by uneven dispersion and insufficient aging, such as construction difficulties, inadequate performance, and unstable film quality, thus ensuring the coating's excellent performance and quality.

[0064] Example 1: A root-blocking polyurethane waterproof coating comprises the following ingredients, calculated by weight: 80% polyurethane prepolymer, 10% root-blocking additive, 10% filler, 10% solvent, 3% hindered amine light stabilizer, 1.5% antioxidant, 2% silane coupling agent, 2% rheological additive, and 0.5% nano-silver particles.

[0065] The polyurethane prepolymer is prepared by reacting polyether polyol and isocyanate monomer in the presence of a catalyst. The molecular weight of the polyether polyol is in the range of 4000. The isocyanate monomer includes one or more of aliphatic isocyanate and aromatic isocyanate. The catalyst is dibutyltin dilaurate, and its usage is 0.1% of the total mass of the reactants.

[0066] The root-blocking additive is sodium bentonite, the montmorillonite content of the sodium bentonite is not less than 80%, the cation exchange capacity is between 120mmol / 100g, and it has undergone organic modification. The modifier is organic silane and organic quaternary ammonium salt, the mass ratio of the two is 1:3, and the total amount of the modifier is 25% of the mass of the sodium bentonite.

[0067] The filler is a mixture of fine-grained quartz sand and kaolin, the particle size of the fine-grained quartz sand is 50 μm, the particle size of the kaolin is 10 μm, and the mass ratio of the fine-grained quartz sand to the kaolin is 4:1.

[0068] The solvent is a mixed solvent of ethyl acetate and propylene glycol methyl ether acetate, and the volume ratio of ethyl acetate to propylene glycol methyl ether acetate is 3:1.

[0069] The hindered amine light stabilizer is a diester of sebacic acid, and the number of piperidine rings in the molecular structure is not less than 2.

[0070] The antioxidant is a compound of a phenolic antioxidant and a phosphite antioxidant, the phenolic antioxidant is antioxidant 1010, and the phosphite antioxidant is triester phosphite, and the mass ratio of the two is 2:1.

[0071] The silane coupling agent is one or more of gamma-methacryloxypropyltrimethoxysilane and gamma-aminopropyltrimethoxysilane, and its molecular structure contains a hydrolyzable methoxy group or ethoxy group and an organic functional group capable of reacting with the polyurethane prepolymer.

[0072] The rheological additive is fumed silica with a specific surface area of ​​300m 2 / g, and regulates the rheological properties of the coating by forming a hydrogen bond network structure in the coating system.

[0073] A method for preparing a root-barrier polyurethane waterproof coating, for use in a root-barrier polyurethane waterproof coating, the method comprising the following steps: S1. Add the polyurethane prepolymer to a high-speed stirring device and stir at a speed of 7000 r / min. Add the solvent and stir for 10 minutes. S2, add root inhibitor additive, filler, hindered amine light stabilizer, antioxidant, silane coupling agent, rheological additive, and nano silver particles in sequence, and continue stirring for 15 minutes; S3. Transfer the mixture to an ultrasonic dispersion device and ultrasonically disperse it for 20 minutes at a frequency of 35 kHz and a power of 250 W. S4. Finally, perform low-speed stirring and aging under stirring at a speed of 500 r / min, a temperature controlled at 50°C, and a stirring time of 15 minutes to obtain a root-blocking polyurethane waterproof coating.

[0074] Example 2: This embodiment differs from the above-mentioned embodiment 1 in that: A root-blocking polyurethane waterproof coating comprises the following ingredients, calculated by weight: 70% polyurethane prepolymer, 5% root-blocking additive, 5% filler, 5% solvent, 1% hindered amine light stabilizer, 0.5% antioxidant, 0.5% silane coupling agent, 0.5% rheological additive, and 0.1% nano-silver particles.

[0075] Example 3: This embodiment differs from the above-mentioned embodiment 1 in that: A root-blocking polyurethane waterproof coating comprises the following ingredients, calculated by weight: 75% polyurethane prepolymer, 7.5% root-blocking additive, 7.5% filler, 7.5% solvent, 2% hindered amine light stabilizer, 1% antioxidant, 1.25% silane coupling agent, 1.25% rheological additive, and 0.3% nano-silver particles.

[0076] Table 1: contrast Existing materials Example 1 Example 2 Example 3 tensile strength 3.0MPa 3.8MPa 3.2MPa 3.5MPa Elongation at break 550％ 650％ 580％ 620％ Tear strength 16N / mm 22N / mm 18N / mm 20N / mm Impermeability 0.3MPa, 30min 0.3MPa, 45min 0.3MPa, 35min 0.3MP, 40min The table above compares existing materials. The new root-blocking polyurethane waterproof coating differs from existing coatings in its component ratios, and shows an upward trend in key performance indicators. This enhances the overall performance of the coating and optimizes and upgrades the product, improving not only its tensile strength, elongation at break, tear strength, and impermeability, but also providing more options for adapting to different engineering scenarios. This addresses the mechanical and waterproof performance deficiencies and compatibility limitations of existing coatings, enabling their more reliable application in various waterproofing and root-blocking projects.

[0077] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A root barrier polyurethane waterproof coating, characterized in that: Calculated by weight, it contains the following ingredients: polyurethane prepolymer 70%-80%, root barrier additive 5%-10%, filler 5%-10%, solvent 5%-10%, hindered amine light stabilizer 1%-3%, antioxidant 0.5%-1.5%, silane coupling agent 0.5%-2%, rheological additive 0.5%-2%, and nano silver particles 0.1%-0.5%.

2. A root barrier polyurethane waterproof coating according to claim 1, characterized in that: The polyurethane prepolymer is prepared by reacting a polyether polyol and an isocyanate monomer in the presence of a catalyst. The molecular weight of the polyether polyol is in the range of 2000-4000. The isocyanate monomer includes one or more of aliphatic isocyanate and aromatic isocyanate. The catalyst is dibutyltin dilaurate, and its usage is 0.05%-0.1% of the total mass of the reactants.

3. The root barrier polyurethane waterproof coating according to claim 1, characterized in that: The root-blocking additive is sodium bentonite, the montmorillonite content of the sodium bentonite is not less than 80%, the cation exchange capacity is between 80-120 mmol / 100 g, and the sodium bentonite has been organically modified. The modifier is organic silane and organic quaternary ammonium salt, and the mass ratio of the two is 1: (1-3). The total amount of the modifier is 15%-25% of the mass of the sodium bentonite.

4. The root barrier polyurethane waterproof coating according to claim 1, characterized in that: The filler is a mixture of fine-grained quartz sand and kaolin, the particle size of the fine-grained quartz sand is 10-50 μm, the particle size of the kaolin is 2-10 μm, and the mass ratio of the fine-grained quartz sand to the kaolin is (2-4):

1.

5. The root barrier polyurethane waterproof coating according to claim 1, characterized in that: The solvent is a mixed solvent of ethyl acetate and propylene glycol methyl ether acetate, and the volume ratio of ethyl acetate to propylene glycol methyl ether acetate is (1-3):

1.

6. The root barrier polyurethane waterproof coating according to claim 1, characterized in that: The hindered amine light stabilizer is sebacic acid diester, and the number of piperidine rings in the molecular structure is not less than 2.

7. The root barrier polyurethane waterproof coating according to claim 1, characterized in that: The antioxidant is a compound of a phenolic antioxidant and a phosphite antioxidant, wherein the phenolic antioxidant is antioxidant 1010 and the phosphite antioxidant is triester phosphite, and the mass ratio of the two is (1-2):

1.

8. The root barrier polyurethane waterproof coating according to claim 1, characterized in that: The silane coupling agent is one or more of gamma-methacryloxypropyltrimethoxysilane and gamma-aminopropyltrimethoxysilane, and its molecular structure contains a hydrolyzable methoxy group or ethoxy group and an organic functional group capable of reacting with the polyurethane prepolymer.

9. The root barrier polyurethane waterproof coating according to claim 1, characterized in that: The rheological additive is fumed silica with a specific surface area of ​​150-300 m² / g. It adjusts the rheological properties of the coating by forming a hydrogen bond network structure in the coating system.

10. A method for preparing a root-barrier polyurethane waterproof coating, characterized in that: A root-barrier polyurethane waterproof coating according to any one of claims 1 to 9, the method comprising the following steps: S1. Add the polyurethane prepolymer to a high-speed stirring device and stir at a speed of 5000-7000 r / min. At the same time, add the solvent and stir for 5-10 minutes; S2. Add root inhibitor additive, filler, hindered amine light stabilizer, antioxidant, silane coupling agent, rheological additive, and nanosilver particles in sequence, and continue stirring for 10-15 minutes; S3. Transfer the mixture to an ultrasonic dispersion device and ultrasonically disperse it for 15-20 minutes at a frequency of 25-35 kHz and a power of 150-250 W; S4. Finally, the mixture is stirred and matured at a low speed with a stirring speed of 300-500 r / min, the temperature is controlled at 40-50° C., and the stirring time is 10-15 minutes to obtain the root-blocking polyurethane waterproof coating.

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