Two-component polyurethane waterproof coating as well as preparation method and application thereof

Abstract

The invention provides a two-component polyurethane waterproof coating and a preparation method and application thereof, the two-component polyurethane waterproof coating comprises a first component and a second component, the first component comprises a polyurethane prepolymer and a latent curing agent; the second component comprises a first plasticizer, a functional aid, a solid filler and a first organic solvent, the polyurethane prepolymer is obtained by polymerization reaction of polyether glycol, polyether triol and isocyanate, and the latent curing agent comprises any one of an aldimine curing agent and an oxazolidine curing agent.

Description

Technical Field

[0001] This disclosure relates to the field of waterproof coating technology, and in particular to a two-component polyurethane waterproof coating, its preparation method, and its application. Background Technology

[0002] Currently, the construction industry's demand for high-quality buildings is growing rapidly, driving continuous improvements in the standards of building materials in terms of environmental friendliness, waterproofing performance, and durability. In the field of waterproofing materials, two-component polyurethane waterproofing coatings, with their excellent comprehensive performance, have become one of the preferred materials for waterproofing projects in important infrastructure, underground engineering, water conservancy facilities, and buildings operating in harsh environments. Two-component polyurethane waterproofing coatings typically consist of component A, containing prepolymer, and component B, containing curing agents, fillers, etc. Components A and B need to be mixed on-site to react and cure, forming a dense, tough, and seamless rubber-like film. Compared to single-component polyurethane waterproofing coatings, they have the following outstanding performance advantages: a wider range of adjustable mechanical properties, adapting to the strength requirements of different scenarios; higher solids content, effectively improving film quality and waterproofing durability; higher tolerance to construction environments, less prone to bubble defects due to environmental factors, and easier to achieve complete adhesion and seamless construction with the substrate, fundamentally eliminating the risk of water seepage.

[0003] However, two-component polyurethane waterproof coatings still have inherent problems in practical applications: because the curing reaction starts immediately after the A and B components are mixed, the working time is too short. When applying to large areas or performing fine treatment on complex nodes such as corners and pipe roots, the coating is prone to rapid thickening or even gelling, which not only increases the difficulty of construction but also seriously affects the film quality and weakens the waterproofing effect. On the other hand, the time it takes for the coating film to reach usable strength after curing is relatively long, which significantly prolongs the construction period and increases construction costs. Especially in outdoor construction scenarios, the coating film that has not formed effective strength is easily washed away by sudden rain or damaged by people stepping on it or subsequent work, ultimately leading to the failure of the initial construction. Summary of the Invention

[0004] In view of this, in order to at least partially solve one of the aforementioned technical problems, this disclosure provides a two-component polyurethane waterproof coating, its preparation method, and its application.

[0005] According to one embodiment of this disclosure, a two-component polyurethane waterproof coating is provided, comprising a first component and a second component, wherein the first component comprises:

[0006] Polyurethane prepolymer, latent curing agent;

[0007] The second component includes:

[0008] The first plasticizer, functional additives, solid fillers, and first organic solvent, among which,

[0009] Polyurethane prepolymers are obtained by the polymerization reaction of polyether diols, polyether triols, and isocyanates.

[0010] Latent curing agents include any one of aldehyde-imide curing agents and oxazolidine curing agents.

[0011] According to another embodiment of this disclosure, a method for preparing the above-mentioned two-component polyurethane waterproof coating is provided, comprising:

[0012] After mixing polyether diol and polyether triol, the mixture is heated at 110~120℃ and dehydrated under vacuum until the water content of the system reaches below 500ppm. After cooling to 80~85℃, isocyanate is added and polymerization reaction is carried out for 1~3 hours to obtain polyurethane prepolymer. The temperature is further cooled to 55~60℃, and latent curing agent is added to polyurethane prepolymer and stirred. After vacuum degassing, the first component is obtained.

[0013] After heating the first plasticizer to 80~90℃, add functional additives and solid fillers and stir to disperse. Then add the first organic solvent and continue stirring. After vacuum degassing, the second component is obtained.

[0014] The first component and the second component are mixed in a certain weight ratio to obtain a two-component polyurethane waterproof coating.

[0015] According to another embodiment of this disclosure, the application of the above-described two-component polyurethane waterproof coating in waterproofing construction surfaces is provided.

[0016] According to the two-component polyurethane waterproof coating disclosed herein, by introducing a latent curing agent into the first component, the agent's extremely low reactivity with the isocyanate groups (-NCO) in the polyurethane prepolymer at room temperature effectively delays the crosslinking reaction in the initial stage of coating mixing, thereby significantly extending the construction operation time and avoiding the difficulties in application and film defects caused by rapid gelation of traditional coatings. Simultaneously, after film formation, trace amounts of moisture in the environment or system will first react with -NCO to generate amino groups, which then slowly react with the -NCO groups to generate amino groups. These amino groups, along with the highly reactive primary amines generated by the hydrolysis of the latent curing agent after film formation, jointly trigger rapid crosslinking, accelerating the construction of coating strength and thus shortening the time to achieve strength. While ensuring film quality and mechanical properties, this coating achieves comprehensive optimization of construction convenience, engineering efficiency, and economy, meeting the stringent requirements of building waterproofing projects for coating performance. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments.

[0018] The endpoints and any values ​​of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this disclosure.

[0019] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0020] In this disclosure, the term "operating time" refers to the time it takes for the coating to maintain a usable application viscosity after mixing. If the operating time is too short, the coating may rapidly thicken or even gel during large-area application or intricate treatment of complex details (such as corners and pipe roots), resulting in poor leveling, difficulty in application, and visible seams, severely impacting film quality and waterproofing performance. The term "strength-building time" refers to the time it takes for the coating to reach usable strength after curing. If this time is too long, it will significantly extend the construction period and increase construction costs. More importantly, during outdoor application, if the coating cannot develop effective strength for an extended period, it is highly susceptible to damage from sudden rain or from being trampled on or damaged during subsequent processes, rendering the entire application ineffective.

[0021] In the process of developing this disclosure, it was discovered that when applying two-component coatings, the curing reaction begins immediately after mixing the two components, gradually forming a rubber-like film. This process presents two main contradictions: First, the retention time of the usable application viscosity after mixing is too short. During large-area construction or treatment of complex nodes (such as corners and pipe roots), the coating tends to thicken rapidly or even gel, resulting in poor leveling, difficulty in application, and visible seams, severely impacting film quality and waterproofing effectiveness. Second, the time required for the coating to reach usable strength after curing is too long, significantly extending the construction period and increasing costs. In outdoor construction, the coating cannot develop effective strength for an extended period, making it highly susceptible to damage from sudden rain or trampling and subsequent processes, rendering all previous work ineffective. This highlights the critical contradiction between "operating time" and "strength-reaching time." Therefore, while ensuring the excellent mechanical properties of the two-component polyurethane waterproof coating, achieving a long operating time to guarantee construction quality and a short strength-reaching time to improve efficiency and reduce risk has become the core issue for upgrading this coating technology, and is of great significance for promoting the development of high-performance waterproof materials.

[0022] Based on this, this disclosure aims to develop a two-component polyurethane waterproof coating that combines a "long working time" with a "short strength development time." Its core principle lies in cleverly resolving the contradiction between the application window and early strength development in traditional products through the synergistic design and reaction kinetic control of the first and second components. The specific technical approach is as follows:

[0023] First, the innovative introduction of latent curing agent technology into the first component is key to extending the working time. The latent curing agent hardly reacts with isocyanate groups (-NCO) at room temperature, thus ensuring the storage stability of the first component and a sufficiently long viscosity retention period (i.e., "working time") in the initial mixing stage of the coating. After the two components are mixed and coated into a film, the latent curing agent preferentially hydrolyzes with trace amounts of moisture in the environment or system, generating highly reactive primary amine groups. These newly generated active groups then rapidly crosslink with the -NCO groups in the first component, forming a dense polyurethane / polyurea network. This two-step "hydrolysis-re-crosslinking" process postpones the crucial film-forming crosslinking step, providing ample "working time" for precise application over large areas and complex details.

[0024] Secondly, this disclosure innovates the preparation process of the second component, achieving energy saving and consumption reduction. Traditional processes typically require high-temperature vacuum dehydration of raw materials such as polyols and fillers to avoid the reaction of moisture in the second component with the prepolymer of the first component, generating carbon dioxide bubbles, resulting in extremely high energy consumption. This disclosure, through precise formulation design, allows the second component to contain a suitable amount of trace water without the need for high-temperature dehydration. This not only significantly reduces energy costs in the production process but also provides a reactant basis for subsequent rapid curing. The presence of trace water synergistically promotes the rapid construction of coating strength. After coating application, this trace water first reacts with -NCO to generate amino groups, which then rapidly react with other -NCO groups to form urea bonds, resulting in a polyurea structure with rapid strengthening characteristics. The first step of this reaction is relatively slow, which can also extend the working time; however, this reaction releases carbon dioxide, and its total amount must be strictly controlled, otherwise, bubble defects will occur in the coating.

[0025] In summary, the parallel and synergistic effects of this water vapor crosslinking and latent curing agent decomposition reaction, after the operation time, utilize the rapid reaction of primary amines to quickly form a crosslinking network inside the coating film, thereby significantly "shortening the time to achieve strength".

[0026] Finally, by controlling the addition and compounding of the chain extender and polyol in the second component, the final film-forming properties can be precisely controlled. The chain extender can rapidly react with -NCO to form hard segments, quickly achieving initial cross-linking while reducing the -NCO content in the system and minimizing bubble formation. The type and functionality of the polyol determine the flexibility, final strength, and cross-linking density of the coating. By balancing the addition of both, the reaction rate, bubble generation and expulsion, and the micro-phase separation structure of the coating can be precisely controlled. This ensures both a long operating time and a short time to achieve strength, while optimizing the leveling properties of the coating, reducing bubbles, and maintaining high strength and high elongation as final mechanical properties.

[0027] In summary, this disclosure, through the combination of "latent curing delayed triggering" and "trace water synergistic rapid curing," supplemented by the energy-saving process of the second component and refined component control, successfully achieves the balance between extending the working time and shortening the strength-building time, providing an innovative solution for the construction and application of high-performance polyurethane waterproof coatings.

[0028] According to one aspect of the present disclosure, a two-component polyurethane waterproof coating is provided, comprising a first component and a second component. The first component comprises a polyurethane prepolymer and a latent curing agent. The second component comprises a first plasticizer, a functional additive, a solid filler, and a first organic solvent. The polyurethane prepolymer is obtained by polymerization of polyether diol, polyether triol, and isocyanate. The latent curing agent comprises any one of aldehyde-imide curing agents and oxazolidine curing agents.

[0029] The two-component polyurethane waterproof coating disclosed herein resolves the contradiction between the application window and early strength development in traditional products through the synergistic design and control of the first and second components. Specifically, firstly, a latent curing agent is introduced into the first component. This agent exhibits low reactivity with the isocyanate groups (-NCO) in the polyurethane prepolymer at room temperature, ensuring the storage stability of the first component and effectively delaying the crosslinking reaction in the initial mixing stage, significantly extending the viscosity retention time and thus the workable time. After coating and film formation, the latent curing agent rapidly hydrolyzes under ambient humidity triggering, generating highly reactive primary amine groups, which then react rapidly with -NCO to form a dense polyurethane / polyurea network. This two-step "hydrolysis-re-crosslinking" reaction mechanism postpones the main curing process, providing ample operating window for large-area application and complex node treatment.

[0030] Secondly, after coating and film formation, trace amounts of moisture in the environment or system will first react with the -NCO groups of the first component to generate amino groups. These amino groups then rapidly react with other -NCO groups to form urea bonds, resulting in a polyurea structure with rapid strengthening characteristics. This parallel and synergistic effect of crosslinking and latent curing agent decomposition utilizes the rapid reaction of primary amines to quickly form a crosslinked network within the coating film, accelerating the construction of the polyurethane waterproof coating film's strength and thus shortening the time required for it to reach its full strength.

[0031] Furthermore, by using polyether diol and polyether triol in the first component, a precise balance between the crosslinking density and flexibility of the final coating film can be achieved. This allows the two-component polyurethane waterproof coating of this disclosure to optimize the reaction rate and mechanical property control while ensuring a long working time (greater than 1 hour) and a short strength-building time (8~24 hours), thereby comprehensively improving film-forming performance.

[0032] Alternatively, an aldehyde-imide latent curing agent, such as Shandong Yihang 292 or Zhejiang Jinfeng 366A, can be used.

[0033] According to embodiments of this disclosure, the raw materials in the first component, by weight, include: a polyurethane prepolymer obtained by polymerization of 30-65 parts of polyether diol, 10-30 parts of polyether triol, and 10-25 parts of isocyanate; and 5-15 parts of latent curing agent.

[0034] According to embodiments of this disclosure, the polyether diol can be, for example, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 65 parts, etc.; the polyether triol can be, for example, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, etc.; the isocyanate can be, for example, 10 parts, 15 parts, 20 parts, 25 parts, etc.; and the latent curing agent can be, for example, 5 parts, 8 parts, 10 parts, 13 parts, 15 parts, etc.

[0035] Adjusting each raw material in the first component to the above range helps to regulate the molecular structure and reactivity of the polyurethane prepolymer. Through the low-activity inhibition at room temperature between the latent curing agent and the terminal -NCO groups of the prepolymer, and the high-activity triggering crosslinking effect after film formation, it effectively solves the contradiction that traditional two-component polyurethane waterproof coatings have short operation time after mixing, making it difficult to meet the construction needs of large areas / complex nodes; at the same time, the curing time is long, extending the construction period and making them susceptible to damage from environmental factors.

[0036] According to embodiments of this disclosure, the isocyanate is an aliphatic or aromatic isocyanate with a functionality greater than or equal to 2. The isocyanate can react with the hydroxyl groups (-OH) of the polyether polyol in the first component, trace amounts of water in the second component, and the amino groups (-NH2) generated from the hydrolysis of the latent curing agent to form polyurethane / polyurea crosslinks, ultimately forming a dense, tough, rubbery coating film, providing the basic structure required for waterproofing the coating.

[0037] Having an isocyanate functionality of 2 or higher ensures its compatibility with multifunctional polyether polyols, forming a cross-linked network and preventing low cross-linking density and poor mechanical properties in the coating film due to insufficient functionality. In practical applications, the type of isocyanate can be flexibly selected according to the needs of the application scenario.

[0038] According to embodiments of this disclosure, the first component further includes: 0.1 to 20 parts of a second plasticizer, and / or, 0.1 to 10 parts of a second organic solvent, and / or, 0.1 to 1.5 parts of a functional additive.

[0039] Optionally, the second plasticizer can be 0.1 parts, 1 part, 5 parts, 10 parts, 15 parts, 20 parts, etc.; the second organic solvent can be 0.1 parts, 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, etc.; and the functional additive can be 0.1 parts, 0.2 parts, 0.5 parts, 0.8 parts, 1.0 parts, 1.5 parts, etc.

[0040] In some embodiments, functional additives include any one or more of defoamers, leveling agents, anti-settling agents, coupling agents, antioxidants, thixotropic agents, retarder agents, and hydrolysis accelerators. Functional additives can ensure system storage stability (e.g., anti-settling agents prevent coating delamination, antioxidants prevent coating degradation and oxidation), optimize application and film-forming effects (e.g., defoamers eliminate bubbles, leveling agents promote coating smoothness), and regulate reaction processes (e.g., hydrolysis accelerators accelerate film strength formation).

[0041] In some embodiments, the second organic solvent is selected from one or more of benzene, xylene, solvent oil, ethyl acetate, butyl acetate, N,N-dimethylformamide, and dimethyl sulfoxide. Organic solvents can reduce the viscosity of the system, facilitating application, improving the compatibility of components and preventing uneven dispersion, and also assisting in vacuum degassing to reduce film-forming defects.

[0042] In some embodiments, the second plasticizer includes one or more of chlorinated paraffin, dioctyl phthalate, dibutyl phthalate, diisononyl phthalate, citrate esters, vegetable oil esters, and sebacic acid esters. The plasticizer added to the first component can adjust the flexibility of the polyurethane waterproof coating film, preventing the film from becoming too brittle and prone to cracking, while also improving the flowability of the mixed components and ensuring storage and application stability.

[0043] According to embodiments of this disclosure, the raw materials in the second component, by weight, include: 15-35 parts of a first plasticizer; 0.3-4 parts of a functional additive; 45-80.5 parts of a solid filler; and 5-12 parts of a first organic solvent.

[0044] According to embodiments of this disclosure, the first plasticizer may be, for example, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, etc.; the functional additive may be, for example, 0.3 parts, 0.5 parts, 1 part, 2 parts, 3 parts, 4 parts, etc.; the solid filler may be, for example, 45 parts, 50 parts, 60 parts, 70 parts, 80 parts, 80.5 parts, etc.; and the organic solvent may be, for example, 5 parts, 8 parts, 10 parts, 12 parts, etc.

[0045] In some embodiments, the functional additives include at least one selected from dispersants, defoamers, pigments, and organometallic catalysts. The dispersant reduces the surface tension of the second component solid particles, prevents particle agglomeration, and avoids insufficient local strength of the coating film due to particle agglomeration. The dispersant can be selected from any one of BYK AT-203, BYK-104S, and Afcona-S527.

[0046] In some embodiments, the defoamer can be selected from any one of BYK A535, Defom 5800, and Afcona-2020. The defoamer can suppress the entrapment of air during the coating mixing and scraping process, prevent defects such as pinholes and bubbles from appearing after the coating film is cured, and ensure the density of the coating film.

[0047] In some embodiments, the pigment is selected from any one or more of carbon black, titanium dioxide, iron yellow, iron red, and phthalocyanine green, which can provide a variety of colors according to project requirements and improve the appearance integrity of waterproof projects.

[0048] In some embodiments, the organometallic catalyst is selected from one or more of organotin catalysts, zinc catalysts, and bismuth catalysts, preferably dibutyltin dilaurate (T-12). The catalyst can regulate the reaction rate, reduce the activation energy of the reaction between isocyanate (-NCO) and hydroxyl (-OH) and amino (-NH2) groups, promote the rapid formation of polyurethane / polyurea crosslinks, assist the coating film to reach usable strength within the target time, and shorten the construction period.

[0049] According to embodiments of this disclosure, the first plasticizer includes one or more of chlorinated paraffin, dioctyl phthalate, dibutyl phthalate, diisononyl phthalate, citrate esters, vegetable oil esters, and sebacic acid esters. The plasticizer can reduce the viscosity of the mixed coating system, improve the leveling properties of the coating, and weaken intermolecular forces by intercalating between polyurethane molecular chain segments, ensuring that the coating film still has good elongation at break after curing. Simultaneously, it can promote the dispersion of solid components such as additives and fillers in the system, ensuring the storage stability and film uniformity of the coating.

[0050] Solid fillers include one or more of the following: talc, calcium carbonate, bentonite, kaolin, cement, heavy calcium carbonate, barium sulfate, magnesium oxide, calcium oxide, wollastonite, silica fume, and mica powder. The addition of solid fillers can significantly reduce the overall production cost of coatings and improve product cost-effectiveness while ensuring mechanical properties. Specifically, flaky fillers such as talc can enhance the tear strength and abrasion resistance of the coating film; granular fillers such as calcium carbonate can fill system voids, improving the hardness and compressive strength of the coating film; and thixotropic fillers such as bentonite can form a gel structure when stationary, preventing coating stratification during storage and quickly restoring viscosity after mixing and application, avoiding sagging on vertical surfaces and making it suitable for waterproofing applications on roofs, walls, and other vertical surfaces.

[0051] The first organic solvent includes one or more of benzene, xylene, solvent oil, ethyl acetate, butyl acetate, N,N-dimethylformamide, and dimethyl sulfoxide. Butyl acetate is preferred. The organic solvent can dissolve or dilute polyurethane prepolymers, plasticizers, and other components, reducing the viscosity of the mixed coating and improving its smoothness during application. The first and second organic solvents can be the same or different.

[0052] According to embodiments of this disclosure, the second component further includes: 0.1 to 5 parts of polyol and / or 0.1 to 2 parts of chain extender. The polyol is a polyether polyol or a polyester polyol with a molecular weight of 200 to 8000. The polyol can react with the -NCO groups of the polyurethane prepolymer in the first component to regulate the crosslinking density and flexibility of the coating film. An appropriate molecular weight range can adapt to different strength requirements, allowing the coating film to maintain a certain strength while also possessing good elongation, thus preventing brittleness.

[0053] The chain extender is selected from any one of alcohol-based chain extenders, amine-based chain extenders, and alkanolamine-based chain extenders. For example, it can be any one of 3,3'-dichloro-4,4'-diaminodiphenylmethane, 3,5-dimethylthiotoluenediamine, 3,5-diethyltoluenediamine, 4,4'-bis(sec-butylaminodiphenylmethane), triethanolamine, 1,4-butanediol, diethylene glycol, etc. The chain extender can rapidly react with -NCO groups to form hard segment structures, accelerating the initial cross-linking of the coating film, shortening the strength development time, and simultaneously improving the tensile strength and hardness of the coating film, ensuring waterproof durability.

[0054] Furthermore, because the first component uses a latent curing agent, the highly reactive primary amine generated by its hydrolysis after film formation can serve as an efficient chain extension and crosslinking point, significantly contributing to the strength of the coating film. Therefore, the amount of polyol and chain extender added to the second component is reduced compared to conventional two-component polyurethane waterproof coatings. This reduces formulation costs and also helps maintain the viscosity stability of the system during construction, avoiding shortened working time due to excessive chain extender.

[0055] According to embodiments of this disclosure, the weight ratio of the first component and the second component is 1:1 to 2, for example, it can be 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, etc. This weight ratio ensures that the active ingredients (such as -NCO groups and active groups in the first plasticizer) in the two components reach a suitable reaction ratio. This avoids insufficient reaction and decreased coating performance due to an excess of one component, and also adapts to the requirements of different construction scenarios regarding coating viscosity and film-forming speed, ensuring smooth application and film quality.

[0056] The second component has a water content of 0.07%-0.20%, for example, 0.07%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, etc. The second component retains trace amounts of water from the raw materials. During film formation, this trace water reacts with -NCO in the first component, initially generating unstable carbamic acid which rapidly decomposes into carbon dioxide and highly reactive primary amines. These primary amines can directly and rapidly react with -NCO to form urea bonds, providing early strength to the coating. Furthermore, they can trigger and accelerate the hydrolysis of the latent curing agent, synergistically generating more primary amines to jointly construct a dense three-dimensional cross-linked network. By utilizing the mutually promoting and parallel execution of the reaction pathway initiated by trace water and the hydrolysis pathway of the latent curing agent, the construction of coating strength is further accelerated, thereby effectively shortening the time to achieve strength.

[0057] In addition, the reaction between trace water and -NCO is relatively slow, which helps to extend the operation time. However, this reaction process releases carbon dioxide. Therefore, it is necessary to strictly control the total amount of trace water in the system to avoid excess gas from failing to escape in time and causing bubble defects in the coating.

[0058] According to another embodiment of this disclosure, a method for preparing the above-mentioned two-component polyurethane waterproof coating is provided, comprising:

[0059] After mixing polyether diol and polyether triol, the mixture is heated at 110~120℃ and dehydrated under vacuum until the water content of the system reaches below 500ppm. After cooling to 80~85℃, isocyanate is added and polymerization reaction is carried out for 1~3 hours to obtain polyurethane prepolymer. The temperature is further cooled to 55~60℃, and latent curing agent is added to polyurethane prepolymer and stirred. After vacuum degassing, the first component is obtained.

[0060] After heating the first plasticizer to 80~90℃, add functional additives and solid fillers and stir to disperse. Then add the first organic solvent and continue stirring. After vacuum degassing, the second component is obtained.

[0061] The first component and the second component are mixed in a certain weight ratio to obtain a two-component polyurethane waterproof coating.

[0062] According to embodiments of this disclosure, the first component employs a stepwise cooling process. First, a higher temperature (80-85°C) is used to ensure sufficient synthesis of the polyurethane prepolymer. Then, a latent curing agent is added at a lower temperature (55-60°C). This effectively avoids premature decomposition or reaction of the latent curing agent at higher temperatures, ensuring its latent properties and thus guaranteeing a longer working time for the final coating product. Secondly, the preparation process of the second component eliminates the traditional high-temperature vacuum dehydration step, completing the process solely through heating, stirring, and vacuum degassing. This not only simplifies the production process and improves preparation efficiency but also significantly reduces energy consumption. Furthermore, this preparation method retains a suitable amount of trace water in the second component, providing a foundation for rapid curing and shortened strength development time in conjunction with the latent curing agent after the two-component polyurethane waterproof coating has formed a film.

[0063] According to embodiments of this disclosure, the preparation method further includes: adding at least one of a second plasticizer, a second organic solvent, and a functional additive to the polyurethane prepolymer, and / or adding at least one of a polyol and a chain extender to the first plasticizer. This allows for further selective control of the coating's storage stability, application smoothness, post-film mechanical properties, and curing efficiency, making the coating strength and curing speed more adaptable to different waterproofing scenarios.

[0064] According to another embodiment of this disclosure, the application of the above-described two-component polyurethane waterproof coating in waterproofing construction surfaces is provided.

[0065] According to the embodiments of this disclosure, when the two-component polyurethane waterproof coating of this disclosure is applied to the waterproofing of the construction surface, its long working time (greater than 1 hour) can fully guarantee the work quality of large-area construction and complex node treatment, and avoid the coating defects caused by premature gelation of the coating; at the same time, its short strength time (8~24 hours) significantly improves construction efficiency, shortens the construction period, and effectively reduces the risk of damage to the coating film caused by environmental factors or subsequent operations in the early stage of curing; the final coating film has both excellent mechanical properties and durability, providing highly reliable long-term waterproof protection for building structures.

[0066] According to the embodiments of this disclosure, the two-component polyurethane waterproof coating has an operating time of more than 1 hour. This longer operating time provides sufficient window for construction, meeting the needs of continuous scraping and rolling during large-area waterproofing construction, avoiding interruptions or joint marks caused by rapid thickening of the coating, and facilitating fine treatment of complex nodes such as corners and pipe roots, ensuring uniform and complete coating coverage. This guarantees film quality from the construction stage and reduces waterproofing defects caused by insufficient operating time.

[0067] Two-component polyurethane waterproof coatings reach their usable strength in 8-24 hours after curing. This shorter strength-building time significantly shortens the construction period and reduces labor and management costs. At the same time, the coating can quickly develop usable strength, effectively resisting sudden outdoor rain erosion or preventing damage to the uncured coating caused by subsequent work processes or personnel trampling. This reduces the risk of early construction failure and ensures the overall progress and quality stability of the waterproofing project.

[0068] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments. Unless otherwise specified, specific techniques or conditions in the embodiments are conventional methods, which can be performed according to the techniques or conditions described in the literature in this field or according to the product instructions. It should be noted that, unless otherwise specified, the methods provided in this disclosure are conventional methods, and the reactants and reagents can be obtained from publicly available commercial sources unless otherwise specified.

[0069] Example 1

[0070] This embodiment provides a two-component polyurethane waterproof coating 1, comprising a first component and a second component.

[0071] The first component includes:

[0072] Polyether diol: Wanhua C2020; Polyether triol: Wanhua F3135; Isocyanate: Diphenylmethane diisocyanate (MDI); Aldehyde imide latent curing agent (Shandong Yihang 292); Organic solvent: #150 solvent oil; Functional additive: Hydrolysis accelerator.

[0073] The second component includes:

[0074] Plasticizer: #52 chlorinated paraffin; Polyether triol: Wanhua F3135; Dispersant: BYK AT-203; Pigment: Carbon black; Solid filler: Bentonite, talc, calcium carbonate; Catalyst: Dibutyltin dilaurate (T-12); Organic solvent: #150 solvent oil.

[0075] Table 1 shows the mass ratio of each component in the two-component polyurethane waterproof coatings of Examples 1 to 5 and Comparative Examples 1 to 2 of this disclosure. The mass ratio of each component in the two-component polyurethane waterproof coating 1 of Example 1 is shown in Table 1.

[0076] This embodiment 1 describes the preparation of a two-component polyurethane waterproof coating 1, which specifically includes:

[0077] Polyether diol and polyether triol were mixed and heated under vacuum at 115°C for 3 hours to reduce the water content of the system to below 500 ppm. The mixture was then cooled to 80°C, and isocyanate was added to carry out a polymerization reaction for 3 hours to obtain a polyurethane prepolymer. The mixture was then cooled to 55°C, and an aldehyde-imide latent curing agent, an organic solvent, and a hydrolysis accelerator were added to the polyurethane prepolymer. The mixture was stirred for 0.5 hours, and a vacuum was turned on to remove bubbles for 30 minutes before discharging to obtain the first component.

[0078] After heating the plasticizer, polyether triol, and dispersant to 90°C, add the pigment and solid filler and stir and disperse for 3 hours. Then add the catalyst and organic solvent and continue stirring for 0.5 hours. Turn on the vacuum and degas for 30 minutes before discharging to obtain the second component.

[0079] The first component and the second component are mixed at a weight ratio of 1:1 and stirred evenly to obtain a two-component polyurethane waterproof coating 1.

[0080] Example 2

[0081] This embodiment provides a two-component polyurethane waterproof coating 2. The mass ratio of each component in the two-component polyurethane waterproof coating 2 is shown in Table 1. The preparation method is the same as that in Example 1.

[0082] The first component and the second component are mixed at a weight ratio of 1:1 and stirred evenly to obtain a two-component polyurethane waterproof coating 2.

[0083] Example 3

[0084] This embodiment provides a two-component polyurethane waterproof coating 3. The mass ratio of each component in the two-component polyurethane waterproof coating 3 is shown in Table 1. Compared with Example 1, its second component contains an amine chain extender: MOCA chain extender. The preparation method differs from Example 1 in that the amine chain extender, pigment, and solid filler are added together and stirred.

[0085] The first component and the second component are mixed at a weight ratio of 1:2 and stirred evenly to obtain a two-component polyurethane waterproof coating 3.

[0086] Example 4

[0087] This embodiment provides a two-component polyurethane waterproof coating 4. The mass ratio of each component in the two-component polyurethane waterproof coating 4 is shown in Table 1. Compared with Example 1, no organic solvent is added to the first component. The preparation method differs from Example 1 in that no organic solvent is added during the preparation of the first component.

[0088] The first component and the second component are mixed at a weight ratio of 1:2 and stirred evenly to obtain a two-component polyurethane waterproof coating 4.

[0089] Example 5

[0090] This embodiment provides a two-component polyurethane waterproof coating 5. The mass ratio of each component in the two-component polyurethane waterproof coating 5 is shown in Table 1. Compared with Example 1, no organic solvent is added to the first component, and an amine chain extender, Moca (MOCA), is added to the second component. The preparation method differs from that of Example 1 in that no organic solvent is added when preparing the first component; and the amine chain extender, pigment, and solid filler are added together and stirred when preparing the second component.

[0091] The first component and the second component are mixed at a weight ratio of 1:2 and stirred evenly to obtain a two-component polyurethane waterproof coating 5.

[0092] Comparative Example 1

[0093] This comparative example provides a two-component polyurethane waterproof coating 6. The mass ratio of each component in the two-component polyurethane waterproof coating 6 is shown in Table 1. Compared with Example 1, the first component does not contain a latent curing agent or functional additives, while the second component contains an amine chain extender: MOCA chain extender. The preparation method differs from Example 1 in that: no organic solvents or functional additives are added during the preparation of the first component; while during the preparation of the second component, the amine chain extender, pigment, and solid filler are added together and stirred.

[0094] The first component and the second component are mixed at a weight ratio of 1:1 and stirred evenly to obtain a two-component polyurethane waterproof coating 6.

[0095] Comparative Example 2

[0096] This comparative example provides a two-component polyurethane waterproof coating 7. The mass ratio of each component in the two-component polyurethane waterproof coating 7 is shown in Table 1. Compared with Example 1, its first component contains a plasticizer, but no latent curing agent or functional additives are added. The second component contains an amine chain extender: MOCA chain extender. The preparation method differs from that of Example 1 in that: no organic solvents and functional additives are added during the preparation of the first component; and the amine chain extender, pigment, and solid filler are added together and stirred during the preparation of the second component.

[0097] The first component and the second component are mixed at a weight ratio of 1:2 and stirred evenly to obtain a two-component polyurethane waterproof coating 7.

[0098] Table 1

[0099]

[0100] The two-component polyurethane waterproof coatings from Examples 1-5 and Comparative Examples 1-2 were applied to PTFE boards using a hand-scraping method (scraping film preparation), and cured under standard conditions of 23℃±2℃ and (50±10)% relative humidity to allow the coatings applied to the PTFE boards to solidify into a film. Table 2 compares the film performance of the two-component polyurethane waterproof coatings from Examples 1-5 and Comparative Examples 1-2.

[0101] Table 2

[0102]

[0103] As shown in Table 2, regarding the operating time, the operating time of the two-component polyurethane waterproof coating examples disclosed herein is all above 1 hour, with a maximum of 4 hours, which is far superior to the comparative examples (0.25~1 hour). This fully meets the needs of large-area construction and fine treatment of complex nodes, avoiding film-forming defects caused by insufficient time in traditional coatings. Regarding the strength development time, the examples disclosed herein can reach usable strength in as little as 8 hours, while the other examples are all controlled within 24 hours, which is significantly shorter than the comparative examples (18~36 hours), reducing construction costs and the risk of failure in outdoor construction. In terms of mechanical properties, the tensile strength of the examples covers 2.7~11.3MPa, which can be adapted to different strength requirements (such as underground engineering and roof waterproofing), with an elongation at break of 620%~770% and a tear strength of 24~63N / mm. It has excellent flexibility and resistance to breakage, and can adapt to substrate deformation and resist external forces. Although some mechanical indicators of the comparative examples are similar to those of the examples, the operating time is extremely short or the strength development time is too long. Performance comparisons have verified that this disclosure, through the introduction of latent curing agents, retention of trace amounts of water, and formulation control, not only solves the time conflict of traditional products but also ensures the stability of mechanical properties and adaptability to various scenarios, achieving synergistic optimization of construction convenience and product performance.

[0104] This disclosure provides a two-component polyurethane waterproof coating, its preparation method, and its application, resolving the inherent core contradiction between the "operation time" and "long strength-building time" of two-component polyurethane waterproof coatings. Its advantages and beneficial effects are as follows: During the construction phase, based on the "long operation time," the two-component polyurethane waterproof coating exhibits more user-friendly, more forgiving, and more efficient construction characteristics, meeting the needs of large-area construction and facilitating the fine handling of complex nodes, avoiding material gelation during construction; in terms of quality, the long operation time ensures that the two-component polyurethane waterproof coating has higher, more stable, and more reliable film-forming quality, ensuring sufficient film leveling, reducing defects, and lowering the risk of damage during outdoor construction; in terms of economic benefits, the two-component polyurethane waterproof coating reduces costs by saving labor time, reducing waste, and lowering rework rates; in terms of long-term value and environmental protection, the two-component polyurethane waterproof coating film has excellent comprehensive performance and a long service life, and its production abandons high-temperature dehydration processes, conforming to the trend of sustainable development.

[0105] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A two-component polyurethane waterproof coating, comprising a first component and a second component, characterized in that, The first component includes: Polyurethane prepolymer, latent curing agent; The second component includes: The first plasticizer, functional additives, solid fillers, and first organic solvent, among which, The polyurethane prepolymer is obtained by the polymerization reaction of polyether diol, polyether triol, and isocyanate. The latent curing agent includes any one of aldehyde-imine curing agents and oxazolidine curing agents.

2. The two-component polyurethane waterproof coating according to claim 1, characterized in that, By weight, the raw materials in the first component include: A polyurethane prepolymer obtained by polymerization of 30-65 parts polyether diol, 10-30 parts polyether triol, and 10-25 parts isocyanate; and 5-15 parts of latent curing agent; By weight, the raw materials in the second component include: 15-35 parts of the first plasticizer; 0.3-4 parts of functional additives; Solid filler 45~80.5 parts; 5-12 parts of the first organic solvent; The functional additives include at least one of dispersants, defoamers, pigments, and organometallic catalysts, wherein the organometallic catalysts are selected from one or more of organotin catalysts, zinc catalysts, and bismuth catalysts.

3. The two-component polyurethane waterproof coating according to claim 2, characterized in that, The first component further includes: 0.1 to 20 parts of a second plasticizer, and / or, 0.1 to 10 parts of a second organic solvent, and / or, 0.1~1.5 parts functional additives; The functional additives include any one or more of the following: defoamers, leveling agents, anti-settling agents, coupling agents, antioxidants, thixotropic agents, retarder, and hydrolysis accelerators. The second organic solvent is selected from one or more of benzene, xylene, solvent oil, ethyl acetate, butyl acetate, N,N-dimethylformamide, and dimethyl sulfoxide; The second plasticizer includes one or more of the following: chlorinated paraffin, dioctyl phthalate, dibutyl phthalate, diisononyl phthalate, citrate esters, vegetable oil esters, and sebacic acid esters.

4. The two-component polyurethane waterproof coating according to claim 2, characterized in that, The second component further includes: 0.1-5 parts of polyol and / or 0.1-2 parts of chain extender, wherein, The polyol is a polyether polyol or a polyester polyol with a molecular weight of 200-8000. The chain extender is selected from any one of alcohol chain extenders, amine chain extenders, and alkanolamine chain extenders.

5. The two-component polyurethane waterproof coating according to any one of claims 1 to 4, characterized in that, The isocyanate is an aliphatic isocyanate or an aromatic isocyanate, and the functionality of the isocyanate is greater than or equal to 2. The first plasticizer includes one or more of the following: chlorinated paraffin, dioctyl phthalate, dibutyl phthalate, diisononyl phthalate, citrate esters, vegetable oil esters, and sebacic acid esters. The solid filler includes one or more of the following: talc, calcium carbonate, bentonite, kaolin, cement, superphosphate, barium sulfate, magnesium oxide, calcium oxide, wollastonite, silica fume, and mica powder. The first organic solvent includes one or more of benzene, xylene, solvent oil, ethyl acetate, butyl acetate, N,N-dimethylformamide, and dimethyl sulfoxide.

6. The two-component polyurethane waterproof coating according to claim 1, characterized in that, The weight ratio of the first component to the second component is 1:1~2; The water content in the second component is 0.07%-0.20%.

7. A method for preparing a two-component polyurethane waterproof coating according to any one of claims 1 to 6, characterized in that, The preparation method includes: After mixing polyether diol and polyether triol, the mixture is heated at 110~120℃ and dehydrated under vacuum until the water content of the system reaches below 500ppm. After cooling to 80~85℃, isocyanate is added and polymerization reaction is carried out for 1~3 hours to obtain polyurethane prepolymer. The temperature is further cooled to 55~60℃, and a latent curing agent is added to the polyurethane prepolymer and stirred. After vacuum degassing, the first component is obtained. After heating the first plasticizer to 80~90℃, add functional additives and solid fillers and stir to disperse. Then add the first organic solvent and continue stirring. After vacuum degassing, the second component is obtained. The first component and the second component are mixed in a weight ratio to obtain a two-component polyurethane waterproof coating.

8. The preparation method according to claim 7, characterized in that, Also includes: Add at least one of a second plasticizer, a second organic solvent, and a functional additive to the polyurethane prepolymer, and / or Add at least one of polyol and chain extender to the first plasticizer.

9. The application of a two-component polyurethane waterproof coating according to any one of claims 1 to 6 in waterproofing construction surfaces.

10. The application according to claim 9, characterized in that, The two-component polyurethane waterproof coating has an operable time of more than 1 hour; The two-component polyurethane waterproof coating reaches its service strength after curing in 8 to 24 hours.

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