Flame-retardant waterproofing membrane and method of manufacture and use thereof

Abstract

The present disclosure provides a kind of flame-retardant waterproof roll material and its preparation method and application, belong to waterproof roll material technical field.The flame-retardant waterproof roll material includes successively from top to bottom: modified magnesium oxide flame-retardant coating and roll matrix;Wherein, modified magnesium oxide flame-retardant coating is formed by the solidification of modified magnesium oxide flame-retardant coating containing modified magnesium oxide, expanded graphite and aluminum hydroxide.By innovatively using modified magnesium oxide, aluminum hydroxide and expanded graphite to construct a synergistic flame-retardant system, the organic combination of multiple flame-retardant mechanisms is achieved, the flame-retardant grade of the roll material reaches B1 level of GB 8624-2012 standard, showing excellent fire safety, suitable for engineering scenarios with high requirements for fire and waterproofing, and has broad application prospects.

Description

Technical Field

[0001] This disclosure relates to the field of waterproof membrane technology, and in particular to a flame-retardant waterproof membrane, its preparation method, and its application. Background Technology

[0002] Waterproof membranes are widely used in building roofs, basements, tunnels, and other engineering projects. They are prefabricated in rolls in factories and laid on-site to form a continuous, integral waterproof layer. Their main components include asphalt, polymers (such as polyvinyl chloride, thermoplastic polyolefins, and EPDM rubber), and base materials (such as polyester base and fiberglass base), which are bonded to the substrate through hot-melt, self-adhesive, or mechanical fixing methods. Their core function is to prevent liquid water penetration, thereby protecting the building structure from moisture erosion. However, traditional waterproof membranes (such as modified bitumen waterproof membranes) generally have low flame retardant properties, with most only reaching the B2 level of the GB 8624-2012 standard. In the event of a fire, they are easily flammable and produce molten droplets, which accelerates the spread of fire and fails to meet the fire protection requirements of high-rise buildings, underground projects, and other critical scenarios. Summary of the Invention

[0003] In view of the above, in order to at least partially solve the aforementioned technical problems, this disclosure provides a flame-retardant waterproof membrane, its preparation method and application, and the technical solution provided by this disclosure is as follows.

[0004] According to one embodiment of this disclosure, a flame-retardant waterproof membrane is provided, comprising, from top to bottom: a modified magnesium oxide flame-retardant coating and a membrane substrate; wherein the modified magnesium oxide flame-retardant coating is formed by curing a modified magnesium oxide flame-retardant coating comprising modified magnesium oxide, expanded graphite and aluminum hydroxide.

[0005] According to another aspect of this disclosure, a method for preparing a flame-retardant waterproof membrane is provided, comprising: coating a modified magnesium oxide flame-retardant coating onto the surface of a membrane substrate, followed by hot-pressing curing and cooling to obtain a flame-retardant waterproof membrane.

[0006] According to another aspect of this disclosure, an application of a flame-retardant waterproof membrane in waterproofing projects is provided.

[0007] According to embodiments of this disclosure, a synergistic flame-retardant system of "heat absorption and cooling - physical insulation - smoke suppression and flame retardancy" is constructed by innovatively incorporating modified magnesium oxide, aluminum hydroxide, and expanded graphite into a modified magnesium oxide flame-retardant coating (hereinafter referred to as "flame-retardant coating"). In this system, aluminum hydroxide achieves cooling through dehydration and heat absorption, modified magnesium oxide decomposes under heated conditions to further absorb heat, and expanded graphite expands at high temperatures (e.g., 600°C) to form a dense carbon layer, effectively isolating oxygen and heat transfer. The synergistic effect of the three components enhances the flame-retardant performance of the flame-retardant waterproof membrane (hereinafter referred to as "membrane"), and no toxic gases are produced during combustion. It can be widely applied to various engineering scenarios requiring both fire resistance and waterproofing, such as high-rise building roofs and exterior walls, underground integrated pipe corridors, data center computer rooms, and traffic tunnels, and has broad application prospects. Detailed Implementation

[0008] The embodiments of this disclosure will now be described. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure.

[0009] In this disclosure, GB 8624-2012 refers to the national standard GB 8624-2012 "Classification of Combustion Performance of Building Materials and Products". This standard classifies the combustion performance of building materials and products into four levels: A (non-combustible), B1 (flame-retardant), B2 (combustible), and B3 (flammable).

[0010] Among them, B1 is the flame-retardant material grade. Materials reaching this grade exhibit good flame-retardant properties under fire conditions, are difficult to ignite and sustain combustion when exposed to open flames or high temperatures (such as 600-900℃) in air, and combustion stops spontaneously once the fire source is removed. B1 grade materials can effectively inhibit flame spread and delay fire development. B2 is the combustible material grade. This grade of material has some flame-retardant properties, but it is still easily ignited under open flames or high temperatures (such as 600-900℃), and may continue to burn after the fire source is removed. Compared with B1 grade materials, its fire risk is higher, and its application in construction projects is more restricted. B3 is the flammable material grade. This grade of material has no effective flame-retardant properties, is extremely easy to ignite and burn rapidly, and has an extremely high fire hazard. National standards clearly stipulate that materials that do not meet the B2 grade requirements are all B3 grade and must not be used in construction projects with fire protection requirements.

[0011] Existing flame-retardant waterproof membranes primarily rely on adding large amounts of organic flame retardants to modified bitumen to achieve their flame-retardant function. However, these organic flame retardants are prone to volatilization and migration during use, leading to a significant decrease in the flame-retardant performance of the membrane over time. Furthermore, they release toxic and harmful gases during combustion, posing secondary safety hazards. If inorganic flame retardants are added directly, the poor interfacial compatibility between them and the organic matrix (such as modified bitumen) can easily cause problems such as inorganic flame retardant aggregation, cracking of the flame-retardant coating, and even peeling, thus affecting the integrity of the waterproof layer within the membrane and making it difficult to maintain both good flame-retardant performance and waterproof durability. In addition, the traditional manufacturing process for flame-retardant waterproof membranes is complex, with some processes compromising the membrane's flexibility and increasing construction difficulty. Moreover, under harsh environmental conditions such as humidity, both waterproof and flame-retardant properties tend to decline simultaneously, resulting in a shortened overall service life of the membrane.

[0012] In view of this, this disclosure provides a flame-retardant waterproof membrane, its preparation method, and its application. The membrane consists of a membrane substrate and a modified magnesium oxide flame-retardant coating laminated to its surface. The magnesium oxide surface is modified using a silane coupling agent, and a synergistic flame-retardant system is constructed by co-compacting aluminum hydroxide and expanded graphite. Combined with a coating-hot-pressing integrated molding process, this significantly improves the fire safety of the membrane while effectively alleviating problems such as insufficient flame-retardant performance, weak coating adhesion, and poor waterproof durability found in traditional waterproof membranes.

[0013] Specifically, according to one aspect of the present disclosure, a flame-retardant waterproof membrane is provided, comprising, from top to bottom: a modified magnesium oxide flame-retardant coating and a membrane substrate; wherein the modified magnesium oxide flame-retardant coating is formed by curing a modified magnesium oxide flame-retardant coating comprising modified magnesium oxide, expanded graphite and aluminum hydroxide.

[0014] According to embodiments of this disclosure, a synergistic flame-retardant system of "heat absorption and cooling - physical insulation - smoke suppression and flame retardancy" is constructed by innovatively introducing modified magnesium oxide, aluminum hydroxide, and expanded graphite into the flame-retardant coating. In this system, aluminum hydroxide achieves cooling through dehydration and heat absorption, modified magnesium oxide decomposes under heating conditions to further absorb heat, and expanded graphite expands at high temperatures to form a dense carbon layer, effectively isolating oxygen and heat transfer. The synergistic effect of the three significantly improves the flame-retardant performance of the roll material and does not produce toxic gases during combustion. The flame-retardant rating of this roll material reaches B1 level of GB 8624-2012 standard, belonging to flame-retardant materials with good flame-retardant properties. Furthermore, after a simulated accelerated aging test lasting up to 1000 hours, its flame-retardant performance showed no decline, further proving that the roll material has reliable flame-retardant stability in long-term use and can more effectively delay or suppress the spread of fire under real fire conditions. Based on the above comprehensive performance characteristics, this roll material can be widely used in various engineering scenarios with strict requirements for fire prevention and waterproofing, and has broad application prospects.

[0015] In some embodiments, the thickness of the modified magnesium oxide flame-retardant coating is 0.1-0.3 mm, for example, 0.1 mm, 0.2 mm, or 0.3 mm, but not limited to the listed values. By controlling the thickness of the modified magnesium oxide flame-retardant coating, an extremely thin (e.g., <0.3 mm) and continuous dense flame-retardant protective layer can be formed on the surface of the roll substrate. This thickness range ensures that the flame-retardant coating can fully cover and protect the roll substrate, effectively exerting its flame-retardant effect in the event of a fire, significantly improving the flame-retardant efficiency of the roll, while also avoiding increased costs due to an excessively thick flame-retardant coating (e.g., >0.3 mm).

[0016] In some embodiments, the membrane substrate is a styrene-butadiene-styrene block copolymer (SBS) modified bitumen waterproof membrane with a thickness of 1.5-3.0 mm, such as 1.5 mm, 1.7 mm, 1.9 mm, 2.1 mm, 2.1 mm, 2.3 mm, 2.5 mm, 2.7 mm, and 3.0 mm, but not limited to the listed values. A suitable membrane substrate thickness provides stable mechanical support for the flame-retardant coating, preventing wrinkles or deformation caused by an excessively thin substrate (e.g., <1.5 mm), while also preventing construction inconvenience caused by an excessively thick substrate (e.g., >3.0 mm). The tensile strength of the membrane substrate is ≥8 MPa, and the elongation at break is ≥300%. Suitable tensile strength and elongation at break ensure excellent mechanical strength and flexibility of the membrane substrate while providing a more robust and crack-resistant adhesion base for the flame-retardant coating. This allows the flame-retardant coating to remain tightly bonded to the substrate even under deformations such as bending and stretching, effectively preventing the flame-retardant coating from peeling, cracking, or failing due to deformation or insufficient strength of the substrate.

[0017] In some embodiments, the modified magnesium oxide flame-retardant coating comprises the following components in parts by weight: 30-50 parts modified magnesium oxide, 10-20 parts aluminum hydroxide, 5-10 parts expanded graphite, 20-30 parts waterborne acrylic emulsion, 1-3 parts a first silane coupling agent, 1-2 parts a plasticizer, 0.5-1 parts a defoamer, and 5-20 parts deionized water; wherein the modified magnesium oxide is obtained by modifying magnesium oxide with a second silane coupling agent. This formulation achieves excellent comprehensive performance through the synergistic effect of its components: a synergistic flame-retardant system is constructed with modified magnesium oxide as the core, combined with aluminum hydroxide and expanded graphite; the waterborne acrylic emulsion and the first silane coupling agent together ensure good film-forming properties, flexibility, and strong adhesion to the roll substrate; the plasticizer and defoamer further optimize the application performance and density of the flame-retardant coating. Ultimately, the modified magnesium oxide flame-retardant coating, while possessing a long-lasting and reliable flame-retardant function, is tightly bonded to the membrane substrate, forming a stable, durable, and easy-to-apply flame-retardant waterproof membrane.

[0018] According to embodiments of this disclosure, a highly efficient synergistic flame-retardant system is constructed by innovatively compounding modified magnesium oxide with aluminum hydroxide and expanded graphite in the flame-retardant coating. In this system, magnesium oxide decomposes and absorbs heat when heated, aluminum hydroxide cools down through a dehydration process, and expanded graphite rapidly expands upon contact with fire to form a dense carbon layer, effectively isolating oxygen and heat transfer. The synergistic effect of these three components significantly enhances the flame-retardant performance of the roll material. To further optimize performance, a second silane coupling agent is used to modify the surface of magnesium oxide, successfully introducing organic functional groups onto its surface. This treatment significantly improves the dispersion uniformity of magnesium oxide in the flame-retardant coating and enhances the interfacial adhesion between the flame-retardant coating and the roll material substrate, thereby effectively alleviating the problems of easy agglomeration and easy coating peeling of traditional inorganic flame-retardant fillers. Furthermore, the synergistic flame retardant system uses inorganic compounds, which do not release toxic or harmful gases during combustion. This not only improves the fire safety of the roll material but also aligns with the development trend of green and environmentally friendly building materials, effectively alleviating the potential environmental and safety issues associated with traditional organic flame retardants.

[0019] In some embodiments, the first silane coupling agent and / or the second silane coupling agent are each independently selected from at least one of γ-aminopropyltriethoxysilane, aminopropylphenyltrimethoxysilane, and N-cyclohexyl-aminopropyltrimethoxysilane. The first silane coupling agent is used to improve the dispersion stability of inorganic fillers (such as aluminum hydroxide, expanded graphite, etc.) in the flame-retardant coating, effectively preventing sedimentation and agglomeration of the inorganic fillers. The second silane coupling agent is used to modify the surface of magnesium oxide, introducing organic functional groups to its surface and enhancing the interfacial adhesion between the flame-retardant coating and the roll material substrate. This effectively prevents cracking or peeling of the flame-retardant coating, thereby improving the overall waterproof durability of the roll material by more than 30%, meeting the service requirements of underground engineering, rail transportation, and other applications in long-term humid environments. The plasticizer is dioctyl phthalate. This plasticizer effectively improves the processability and film-forming flexibility of the flame-retardant coating, giving it good leveling and workability during application. The defoamer is an organosilicone defoamer, such as polydimethylsiloxane, modified polysiloxane emulsion, or organosilicone composite defoamer. This type of defoamer disperses rapidly and can break up existing bubbles and inhibit the formation of new bubbles during the preparation and application of flame-retardant coatings.

[0020] It is understood that the first and second silane coupling agents of this disclosure may be the same or different, and preferably both are γ-aminopropyltriethoxysilane. This preferred scheme can achieve a dual synergistic enhancement effect, constructing a highly continuous and compatible interfacial chemical environment between the modified magnesium oxide and the components in the flame-retardant coating, significantly enhancing the interaction between the inorganic flame-retardant fillers (such as aluminum hydroxide, expanded graphite) and the aqueous acrylic emulsion. This improves the density, adhesion, water resistance, and durability of the flame-retardant coating, effectively preventing cracking or peeling of the flame-retardant coating due to interfacial defects, thereby ensuring the long-term stability of flame-retardant performance. According to another aspect of this disclosure, a method for preparing a flame-retardant waterproof membrane is provided, comprising: coating a modified magnesium oxide flame-retardant coating onto the surface of a membrane substrate, followed by hot-press curing and cooling to obtain a flame-retardant waterproof membrane.

[0021] According to embodiments of this disclosure, a prepared modified magnesium oxide flame-retardant coating is uniformly applied to the surface of a roll substrate (such as SBS modified bitumen waterproof roll). The coated roll is then placed into a heating and pressurizing device (such as a hot-press curing chamber). Under a certain temperature (such as 100-120°C) and pressure (such as 0.5-1.0 MPa), the polymer base material (such as water-based acrylic emulsion) in the flame-retardant coating melts and flows. Simultaneously, the first silane coupling agent in the flame-retardant coating undergoes a further hydrolysis and condensation reaction, forming stable chemical bonds and physical entanglements within the flame-retardant coating and between the flame-retardant coating and the roll substrate. This achieves full curing of the flame-retardant coating and a strong bond between it and the roll substrate. After hot-press curing, the coating is cooled and shaped, then cut to obtain the final flame-retardant waterproof roll. This preparation process can be implemented using conventional coating and hot-pressing equipment, without the need for additional dedicated production lines. The raw material supply is stable and readily available, and the production cost can be reduced by 20%-30% compared to imported high-end flame-retardant and waterproof membranes. The process is simple and feasible, and has the potential for large-scale industrial production.

[0022] In some embodiments, the coating thickness of the modified magnesium oxide flame-retardant coating is 0.2-0.6 mm, for example, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, or 0.6 mm, but not limited to the listed values. Controlling the coating thickness within a reasonable range ensures that the flame-retardant coating forms a continuous and dense flame-retardant protective layer on the surface of the roll substrate, fully utilizing its flame-retardant and adhesion-enhancing effects, while avoiding material waste and prolonged construction periods caused by excessively thick flame-retardant coatings (e.g., >0.6 mm). Furthermore, this thickness range is suitable for conventional coating processes, easy to control, and can optimize production costs while meeting environmental requirements.

[0023] In some embodiments, the specific steps of hot-press curing include: after coating the roll substrate with a flame-retardant coating, pre-baking is performed in a hot-press curing chamber, with the pre-baking temperature controlled at 60-70℃ and the pre-baking time at 10-15 minutes. The pre-baking temperature can be 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, or 70℃, but is not limited to the listed values. The pre-baking time can be 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, or 15 minutes, but is not limited to the listed values. Pre-baking can slowly remove moisture or volatiles from the flame-retardant coating, preventing the rapid escape of moisture or volatiles during subsequent hot-press curing, which could lead to the formation of pores or bubbles inside the flame-retardant coating. This improves the uniformity and density of the flame-retardant coating, laying a good foundation for subsequent hot-press curing. After pre-baking, raise the temperature to 100-120℃ and apply a pressure of 0.5-1.0 MPa, then hot-press cure for 20-30 minutes under these conditions. The temperature can be 100℃, 105℃, 110℃, 115℃, or 120℃, but is not limited to the listed values. The applied pressure can be 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, or 1.0 MPa, but is not limited to the listed values. The hot-press curing time can be 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes, or 30 minutes, but is not limited to the listed values.

[0024] In some embodiments, the modified magnesium oxide flame-retardant coating is prepared by the following method: an aqueous acrylic emulsion, plasticizer, defoamer, first silane coupling agent, and deionized water are mixed to obtain a mixed solution; modified magnesium oxide, aluminum hydroxide, and expanded graphite are added sequentially to the mixed solution, and the mixture is stirred until homogeneous to obtain the modified magnesium oxide flame-retardant coating. In this preparation method, a homogeneous mixed solution is prepared first, and then solid fillers (such as modified magnesium oxide, aluminum hydroxide, and expanded graphite) are added stepwise, which helps to achieve sufficient dispersion of each component, especially avoiding agglomeration of solid fillers during the addition process, thus improving the stability and uniformity of the flame-retardant coating. This process is simple, highly operable, and suitable for continuous industrial production. The resulting flame-retardant coating has good coating performance and is easy to apply in subsequent construction.

[0025] In some embodiments, the stirring rate during the mixing process of the aqueous acrylic emulsion, plasticizer, defoamer, first silane coupling agent, and deionized water is 500-800 r / min, for example, 500 r / min, 600 r / min, 700 r / min, or 800 r / min, but not limited to the listed values. The stirring time is 5-15 min, for example, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, or 15 min, but not limited to the listed values. Subsequently, after adding modified magnesium oxide, aluminum hydroxide, and expanded graphite, the stirring rate is 1500-2000 r / min, for example, 1500 r / min, 1600 r / min, 1700 r / min, 1800 r / min, 1900 r / min, or 2000 r / min, but not limited to the listed values. The stirring time is 30-40 minutes, for example, 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes, or 40 minutes, but is not limited to the values ​​listed.

[0026] In some embodiments, modified magnesium oxide is prepared by mixing magnesium oxide, a second silane coupling agent, and deionized water to obtain a pretreated slurry; heating the pretreated slurry to react; and after the reaction, filtering, drying, and sieving to obtain modified magnesium oxide. By using a second silane coupling agent to graft organic functional groups onto the surface of magnesium oxide, the compatibility between magnesium oxide particles and the polymer matrix (such as aqueous acrylic emulsion) in subsequent flame-retardant coatings is enhanced. The dispersibility of modified magnesium oxide in flame-retardant coatings is significantly improved, making it less prone to agglomeration or sedimentation, which helps to improve the overall uniformity, structural stability, and comprehensive performance of the flame-retardant coating. Furthermore, this preparation method is simple, process-controllable, suitable for large-scale production, has high raw material utilization, and is easy to implement industrially.

[0027] In some embodiments, the particle size of magnesium oxide is 1-5 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, but not limited to the listed values. This particle size range helps to achieve a higher specific surface area, improve the efficiency of magnesium oxide surface modification, and enhance its dispersibility in the pretreated slurry. The mass of the second silane coupling agent is 2%-5% of the mass of magnesium oxide, for example, 2%, 3%, 4%, 5%, but not limited to the listed values. This addition ratio ensures sufficient grafting of organic functional groups onto the magnesium oxide surface while avoiding abnormal viscosity of the pretreated slurry due to excessive addition (e.g., >5%), which could affect subsequent reactions. The mass ratio of deionized water to magnesium oxide is 1:0.5-1:1.5, for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, but not limited to the listed values. This ratio facilitates the formation of a uniform pretreatment slurry, providing a suitable foundation for the hydrolysis of the second silane coupling agent and its effective reaction with magnesium oxide. The mixing time for magnesium oxide, the second silane coupling agent, and deionized water is 5-15 minutes, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 minutes, but not limited to these values. Thorough mixing helps the second silane coupling agent to disperse uniformly and achieve initial hydrolysis, creating favorable conditions for the subsequent magnesium oxide surface modification reaction.

[0028] In some embodiments, magnesium oxide, a second silane coupling agent, and deionized water are mixed to obtain a pretreated slurry, which is then reacted at 80-90°C for 1-2 hours. The reaction temperature can be 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, or 90°C, but is not limited to these values. A suitable reaction temperature facilitates the full reaction of the second silane coupling agent on the magnesium oxide surface, promoting the grafting of organic functional groups, while avoiding silane decomposition or agglomeration of magnesium oxide particles due to excessively high temperatures (e.g., >90°C), which would affect the modification effect. The reaction time can be 1 hour, 1.5 hours, or 2 hours, but is not limited to these values. This reaction time ensures sufficient grafting of the second silane coupling agent onto the magnesium oxide particle surface, thereby providing a high-performance modified magnesium oxide raw material for the subsequent preparation of flame-retardant coatings.

[0029] In some embodiments, after the pretreated slurry reaction is completed, the filtered material is first dried at a temperature of 105-110°C, such as 105°C, 106°C, 107°C, 108°C, 109°C, or 110°C, limited to the listed values. This temperature range effectively removes residual moisture, preventing incomplete drying from affecting subsequent sieving, and also prevents damage to the organic functional groups grafted onto the surface of magnesium oxide particles due to excessively high temperatures (e.g., >110°C), thereby maintaining the performance stability of the modified magnesium oxide. Subsequently, the dried material is sieved through a 190-210 mesh sieve to obtain modified magnesium oxide. The sieve mesh size can be 190 mesh, 200 mesh, or 210 mesh, but is not limited to the listed values. The sieving step can control the particle size distribution of the modified magnesium oxide, effectively remove agglomerates that may form during the drying process, ensure its uniform dispersion in the flame-retardant coating, and improve the smoothness and overall performance of the flame-retardant coating.

[0030] According to another aspect of this disclosure, an application of a flame-retardant waterproof membrane in waterproofing projects is provided.

[0031] According to embodiments of this disclosure, the aforementioned waterproofing projects may include waterproofing projects for the roofs and exterior walls of high-rise buildings, waterproofing projects for underground pipe corridors and tunnels, waterproofing projects for rail transit stations and track sections, and waterproofing projects for key fire-prone areas such as data centers and power distribution rooms. In summary, the flame-retardant waterproof membrane and its preparation method and application provided by this disclosure, through synergistic optimization of the component ratios and process parameters of the flame-retardant coating, achieve a comprehensive improvement in the flame retardancy, adhesion, and waterproof durability of the membrane. Specifically, the flame-retardant coating adopts a synergistic flame-retardant system mainly composed of modified magnesium oxide, aluminum hydroxide, and expanded graphite. Through the synergistic effect of these three components, the flame-retardant performance is significantly enhanced, enabling the membrane to achieve a flame-retardant rating of B1. This system does not release toxic or harmful gases during combustion, conforming to the development trend of green building materials and effectively mitigating the potential environmental and safety risks of traditional organic flame retardants. Surface modification of magnesium oxide particles using silane coupling agents enhances the compatibility between flame-retardant fillers (such as modified magnesium oxide, aluminum hydroxide, and expanded graphite) and polymer matrices (such as water-based acrylic emulsions). This significantly improves the interfacial adhesion between the flame-retardant coating and the membrane substrate (≥1.5 N / mm), effectively preventing cracking and peeling of the flame-retardant coating. Consequently, the overall waterproof durability of the membrane is improved by more than 30%, meeting the stringent service requirements of long-term humid environments such as underground engineering and rail transportation. In terms of manufacturing process, an integrated coating-hot-pressing process is employed. While ensuring flame-retardant and waterproof performance, this process maintains the membrane's good flexibility, alleviating problems such as excessive membrane stiffness and construction difficulties that often arise with traditional processes.

[0032] The present disclosure will be described in detail below with reference to specific embodiments. It should be noted that the described embodiments are merely some, not all, of the embodiments of the present disclosure. Other embodiments obtained by those skilled in the art based on the embodiments of the present disclosure without creative effort are all within the scope of protection of the present disclosure.

[0033] In this embodiment, the substrate is a 2.0mm thick SBS modified bitumen waterproof membrane. Unless otherwise specified, all raw materials used are commercially available products, and their specific specifications and sources will not have a substantial impact on the implementation and expected technical effects of the embodiments of the present invention.

[0034] The performance testing standards and methods for flame-retardant waterproof membranes disclosed in this publication are as follows: The adhesion of the flame-retardant coating is tested according to GB / T 5210-2006 "Paints and Varnishes - Pull-off Adhesion Test". Aging resistance is tested according to the accelerated aging test method in GB / T 18244-2000 "Test Methods for Aging of Building Waterproofing Materials", with an aging time of 1000 hours. After aging, the flame-retardant and waterproof performance of the membrane is tested. Flame-retardant performance is tested according to GB 8624-2012 "Classification of Burning Performance of Building Materials and Products", and the flammability rating is determined. Waterproof performance is tested according to GB / T 328.10-2020 "Test Methods for Building Waterproofing Membranes - Part 10: Impermeability of Bituminous and Polymer Waterproofing Membranes".

[0035] Preparation of modified magnesium oxide

[0036] Magnesium oxide powder with a particle size of 2 μm was placed in a high-speed mixer. 3% (by weight) of silane coupling agent KH-550 (by mass of magnesium oxide) and an equal mass of deionized water were added. The mixture was stirred at low speed for 10 minutes to ensure thorough and uniform mixing. The mixture was then heated to 90°C and maintained at this temperature with continued stirring for 1.5 hours to allow the silane coupling agent to fully graft onto the surface of the magnesium oxide powder. After the reaction, the material was transferred to an oven and dried at 105°C to constant weight. The dried material was then pulverized and passed through a 200-mesh sieve to obtain modified magnesium oxide powder.

[0037] Example 1

[0038] The raw material formula of the flame retardant coating (by weight parts): 35 parts modified magnesium oxide, 15 parts aluminum hydroxide, 7 parts expanded graphite, 25 parts water-based acrylic emulsion, 1 part silane coupling agent γ-aminopropyltriethoxysilane (KH-550), 1 part plasticizer dioctyl phthalate (DOP), 1 part organosilicon defoamer polydimethylsiloxane, and 15 parts deionized water.

[0039] 1. Preparation of flame retardant coating: By weight, water-based acrylic emulsion, plasticizer DOP, silicone defoamer, and deionized water are added to a disperser and stirred at a low speed of 800 r / min for 10 min; then, modified magnesium oxide, aluminum hydroxide, and expanded graphite are added under continuous stirring, and the speed is increased to 1500 r / min, and high-speed dispersion is continued for 30 min, finally obtaining a uniform flame retardant coating without agglomeration.

[0040] 2. Coating operation: Lay the roll substrate flat on the conveyor belt of the scraper coating machine, precisely adjust the scraper gap, and evenly coat the flame retardant coating prepared above onto the surface of the roll substrate, controlling the coating thickness to be 0.2mm.

[0041] 3. Hot-press curing: The coated roll material is sent into a hot-press curing chamber and pre-baked at 60°C for 10 minutes to remove most of the moisture in the flame-retardant coating. Then the temperature is raised to 100°C and a pressure of 0.5 MPa is applied. Under these conditions, the roll material is hot-pressed and cured for 20 minutes to ensure that the flame-retardant coating is tightly bonded to the roll material substrate.

[0042] 4. Cooling and cutting: Allow the cured roll material to cool naturally to room temperature and cut it into standard size rolls with a width of 1m to obtain a flame-retardant waterproof roll material with a flame-retardant coating thickness of 0.1mm.

[0043] Performance test results: The flame retardant rating reaches GB 8624-2012 B1 level; it remains impermeable to water for 30 minutes under 0.3MPa water pressure; the coating adhesion is 1.5N / mm; after 1000h of artificial accelerated aging, the flame retardant rating still remains at B1 level, and the waterproof performance has not decreased, with no cracking or peeling on the coating surface.

[0044] Example 2

[0045] The raw material formula of the flame retardant coating (by weight parts): 40 parts modified magnesium oxide, 18 parts aluminum hydroxide, 9 parts expanded graphite, 20 parts water-based acrylic emulsion, 1 part silane coupling agent KH-550, 1 part plasticizer DOP, 1 part organosilicon defoamer polydimethylsiloxane, and 10 parts deionized water.

[0046] The preparation process was largely the same as in Example 1, except that the preparation process parameters were adjusted: the flame retardant coating was dispersed at high speed at 1500 r / min for 30 min, and then coated with a doctor blade to control the coating thickness to 0.3 mm; the hot-press curing parameters were: pre-baking at 65°C for 12 min, and then hot-press curing at 105°C and 0.6 MPa for 25 min, resulting in a final flame retardant coating thickness of 0.15 mm.

[0047] Performance test results: The flame retardancy rating of the roll material reaches GB 8624-2012 B1 level; it remains impermeable to water for 30 minutes under 0.3MPa water pressure; the coating adhesion is 1.6N / mm; after 1000h of artificial accelerated aging, the flame retardancy rating still remains at B1 level, and the waterproof performance has not decreased, with no cracking or peeling on the coating surface.

[0048] Example 3

[0049] The raw material formula of the flame retardant coating (by weight parts): 45 parts modified magnesium oxide, 20 parts aluminum hydroxide, 11 parts expanded graphite, 15 parts water-based acrylic emulsion, 1 part silane coupling agent KH-550, 1 part plasticizer DOP, 1 part silicone defoamer, and 6 parts deionized water.

[0050] The preparation process was largely the same as in Example 1, except that the process parameters were adjusted: the flame-retardant coating was dispersed at high speed at 1800 r / min for 35 min, and then coated with a doctor blade to control the coating thickness to 0.5 mm. The hot-press curing parameters were: pre-baking at 70°C for 15 min, and then hot-press curing at 115°C and 0.9 MPa for 28 min, resulting in a final flame-retardant coating thickness of 0.25 mm.

[0051] Performance test results: The flame retardancy rating of the roll material reaches GB 8624-2012 B1 level; it remains impermeable to water for 30 minutes under 0.4MPa water pressure; the coating adhesion is 1.8N / mm; after 1000h of artificial accelerated aging, the flame retardancy rating still remains at B1 level, and the waterproof performance has not decreased.

[0052] Comparative Example 1

[0053] The raw material formula of the flame retardant coating (by weight): 30 parts magnesium oxide, 10 parts aluminum hydroxide, 5 parts expanded graphite, 20 parts water-based acrylic emulsion, 1 part silane coupling agent γ-aminopropyltriethoxysilane (KH-550), 1 part plasticizer dioctyl phthalate (DOP), 0.5 parts organosilicon defoamer polydimethylsiloxane, and 10 parts deionized water.

[0054] The preparation process was largely the same as in Example 1, except that the preparation process parameters were adjusted: the flame retardant coating was dispersed at high speed at 1500 r / min for 30 min, coated with a doctor blade, and the coating thickness was 0.2 mm; the hot-press curing parameters were: pre-baking at 60℃ for 10 min, and then hot-pressing at 100℃ and 0.5 MPa for 20 min; the thickness of the obtained flame retardant coating was 0.1 mm.

[0055] Performance test results: The flame retardant rating is GB 8624-2012 B2; no leakage was observed after maintaining a pressure of 0.3MPa for 30 minutes; the coating adhesion was 0.8N / mm. After artificial accelerated aging for 500 hours, the coating showed obvious cracking and peeling, lost its water impermeability, and the flame retardant rating dropped to B3.

[0056] Comparative Example 2

[0057] Flame retardant coating raw material formula (by weight): 55 parts modified magnesium oxide, 0 parts aluminum hydroxide, 0 parts expanded graphite, 25 parts water-based acrylic emulsion, 2 parts silane coupling agent KH-550, 2 parts plasticizer DOP, 2 parts organosilicon defoamer polydimethylsiloxane, and 14 parts deionized water.

[0058] The preparation process was largely the same as in Example 1, except that the preparation process parameters were adjusted: the flame retardant coating was dispersed at high speed at 1500 r / min for 30 min; a doctor blade was used for coating, and the coating thickness was 0.3 mm; the hot-press curing parameters were: pre-baking at 65°C for 12 min, followed by hot pressing at 105°C and 0.6 MPa for 25 min; the thickness of the obtained flame retardant coating was 0.15 mm.

[0059] Performance test results: The flame retardant rating reaches GB 8624-2012 B2 level; it remains impermeable to water for 30 minutes under 0.2MPa pressure; the coating adhesion is 1.2N / mm; after 1000 hours of artificial accelerated aging, the flame retardant rating remains at B2 level, and the waterproof performance shows no decline.

[0060] Comparative Example 3

[0061] Flame-retardant coating raw material formulation (by weight): 0 parts modified magnesium oxide, 55 parts aluminum hydroxide, 0 parts expanded graphite, 25 parts water-based acrylic emulsion, 2 parts silane coupling agent KH-550, 2 parts plasticizer DOP, 2 parts organosilicon defoamer polydimethylsiloxane, 14 parts deionized water

[0062] The preparation process was largely the same as in Example 1, except that the preparation process parameters were adjusted: the flame retardant coating was dispersed at high speed at 1500 r / min for 30 min; a doctor blade was used for coating, and the coating thickness was 0.3 mm; the hot-press curing parameters were: pre-baking at 65°C for 12 min, followed by hot pressing at 105°C and 0.6 MPa for 25 min; the thickness of the obtained flame retardant coating was 0.15 mm.

[0063] Performance test results: The flame retardant rating reaches GB 8624-2012 B2 level; it remains impermeable to water for 30 minutes under 0.2MPa pressure; the coating adhesion is 1.0N / mm; after 1000 hours of artificial accelerated aging, the flame retardant rating drops to B3 level, but the waterproof performance remains unchanged.

[0064] Comparative Example 4

[0065] Flame retardant coating raw material formula (by weight): 0 parts modified magnesium oxide, 0 parts aluminum hydroxide, 55 parts expanded graphite, 25 parts water-based acrylic emulsion, 2 parts silane coupling agent KH-550, 2 parts plasticizer DOP, 2 parts organosilicon defoamer polydimethylsiloxane, and 14 parts deionized water.

[0066] The preparation process was largely the same as in Example 1, except that the preparation process parameters were adjusted: the flame retardant coating was dispersed at high speed at 1500 r / min for 30 min and then coated with a doctor blade to a thickness of 0.3 mm; the hot-press curing parameters were: pre-baking at 65°C for 12 min, followed by hot pressing at 105°C and 0.6 MPa for 25 min; the resulting flame retardant coating thickness was 0.15 mm.

[0067] Performance test results: The flame retardant rating reaches GB 8624-2012 B2 level; it remains impermeable to water for 30 minutes under 0.2MPa pressure; the coating adhesion is 0.5N / mm; after 500 hours of artificial accelerated aging, the flame retardant rating drops to B3 level, but the waterproof performance remains unchanged.

[0068] The results above demonstrate that Examples 1-3 showcase the formulations using a synergistic flame-retardant system of "modified magnesium oxide, aluminum hydroxide, and expanded graphite," combined with additives such as water-based acrylic emulsion and silane coupling agents. Under optimized process conditions, these formulations can produce flame-retardant and waterproof membranes with excellent overall performance. These membranes all exhibit a B1 flame-retardant rating, excellent waterproof performance (0.3-0.4 MPa, impermeable for 30 minutes), good interfacial adhesion (1.5-1.8 N / mm), and outstanding long-term durability (after 1000 hours of accelerated artificial aging, the flame-retardant rating remains at B1, the waterproof performance shows no degradation, and the appearance remains intact).

[0069] Compared to Example 1, the overall performance of the roll material prepared in Comparative Example 1 was reduced due to the use of ordinary magnesium oxide. This was mainly reflected in the following: the initial flame retardant rating was only B2, the adhesion (0.8 N / mm) was low, and cracking and peeling occurred after only 500 hours of accelerated artificial aging, resulting in a significant decline in flame retardant performance (down to B3 rating), and the waterproofing performance also failed. These results indicate that surface modification of magnesium oxide particles is a key factor in achieving good interfacial adhesion, good durability, and long-term flame retardant stability of the flame-retardant coating.

[0070] Comparative Examples 2-4 investigated the flame-retardant coating performance when using modified magnesium oxide, aluminum hydroxide, or expanded graphite as single flame-retardant fillers. The results showed that regardless of the single filler used, the initial flame-retardant rating of the coating could only reach a maximum of B2, failing to reach the B1 level of Examples 1-4. Specifically, the single aluminum hydroxide system (Comparative Example 3) and the single expanded graphite system (Comparative Example 4) both experienced a decrease in flame-retardant rating to B3 after aging, with the single expanded graphite system exhibiting the lowest adhesion (0.5 N / mm). Notably, while Comparative Example 2 (single modified magnesium oxide) performed relatively well in terms of adhesion and aging resistance, its initial flame-retardant rating (B2) and water resistance (0.2 MPa) were still inferior to Examples 1-4. These results further confirm that modified magnesium oxide primarily provides structural support and durability in flame-retardant coatings, while the introduction of aluminum hydroxide (through endothermic decomposition and oxygen dilution) and expanded graphite (through the formation of a dense carbon layer for thermal and oxygen insulation) produces a significant synergistic flame-retardant effect with modified magnesium oxide. The combined effect of these three factors not only upgrades the flame retardancy rating of the roll material to B1, but also effectively enhances the overall protective performance of the flame retardant coating.

[0071] In summary, the flame-retardant waterproof membrane disclosed herein achieves optimized integration of multiple properties through the innovative construction of a synergistic flame-retardant system of modified magnesium oxide, aluminum hydroxide, and expanded graphite. This system not only endows the membrane with excellent fire resistance (meeting the GB 8624-2012 B1 standard), but also enhances the interfacial bonding between the flame-retardant coating and the membrane matrix by modifying the surface of the magnesium oxide particles, thereby improving the membrane's durability and waterproof reliability. Experimental verification shows that the membrane maintains stable performance under long-term use conditions and does not produce toxic or harmful substances during combustion, aligning with the development trend of green building. Its balanced design of comprehensive performance enables it to effectively meet the dual fire and waterproof requirements of various demanding scenarios such as high-rise buildings, underground spaces, and traffic tunnels, demonstrating excellent engineering applicability.

[0072] 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 flame-retardant waterproof membrane, characterized in that, From top to bottom, it includes: a modified magnesium oxide flame-retardant coating and a roll substrate; The modified magnesium oxide flame-retardant coating is formed by curing a modified magnesium oxide flame-retardant coating containing modified magnesium oxide, expanded graphite and aluminum hydroxide.

2. The flame-retardant waterproof membrane according to claim 1, characterized in that, The thickness of the modified magnesium oxide flame-retardant coating is 0.1-0.3 mm; The substrate of the roll is a styrene-butadiene-styrene block copolymer modified bitumen waterproof roll, and the thickness of the substrate is 1.5-3.0 mm.

3. The flame-retardant waterproof membrane according to claim 1, characterized in that, The modified magnesium oxide flame-retardant coating comprises the following components in parts by weight: Modified magnesium oxide 30-50 parts, aluminum hydroxide 10-20 parts, expanded graphite 5-10 parts, water-based acrylic emulsion 20-30 parts, first silane coupling agent 1-3 parts, plasticizer 1-2 parts, defoamer 0.5-1 parts, deionized water 5-20 parts; The modified magnesium oxide is obtained by modifying magnesium oxide with a second silane coupling agent.

4. The flame-retardant waterproof membrane according to claim 3, characterized in that, The first silane coupling agent and / or the second silane coupling agent are each independently selected from at least one of γ-aminopropyltriethoxysilane, aminopropylphenyltrimethoxysilane, and N-cyclohexyl-aminopropyltrimethoxysilane; The plasticizer is dioctyl phthalate; The defoamer is an organosilicone defoamer.

5. A method for preparing a flame-retardant waterproof membrane as described in any one of claims 1 to 4, characterized in that, include: A modified magnesium oxide flame-retardant coating is applied to the surface of the roll substrate, and then cured by hot pressing and cooling to obtain the flame-retardant waterproof roll.

6. The preparation method according to claim 5, characterized in that, The coating thickness of the modified magnesium oxide flame retardant coating is 0.2-0.6 mm.

7. The preparation method according to claim 5, characterized in that, The modified magnesium oxide flame-retardant coating is prepared by the following method: A water-based acrylic emulsion, plasticizer, defoamer, first silane coupling agent, and deionized water are mixed to obtain a mixed solution; Modified magnesium oxide, aluminum hydroxide, and expanded graphite are added sequentially to the mixed solution and mixed evenly to obtain the modified magnesium oxide flame retardant coating.

8. The preparation method according to claim 7, characterized in that, The modified magnesium oxide is prepared by the following method: Magnesium oxide, a second silane coupling agent, and deionized water were mixed to obtain a pretreated slurry. The pretreated slurry is heated to react; After the reaction was completed, the modified magnesium oxide was obtained by filtration, drying and sieving.

9. The preparation method according to claim 8, characterized in that, The magnesium oxide has a particle size of 1-5 μm; The mass of the second silane coupling agent is 2%-5% of the mass of the magnesium oxide; The mass ratio of the deionized water to the magnesium oxide is 1:0.5 to 1:1.5; The reaction temperature of the pretreated slurry is 80-90℃.

10. The application of a flame-retardant waterproof membrane as described in any one of claims 1 to 4 in waterproofing projects.