A weather-resistant fireproof coating for ships based on polysiloxane modification

Abstract

This invention discloses a weather-resistant and fire-retardant coating for ships based on polysiloxane modification. The coating consists of components A and B. Component A includes polysiloxane-modified epoxy resin, microencapsulated ammonium polyphosphate, pentaerythritol, melamine, nano-sized titanium dioxide, aluminum silicate fiber, and additives; component B is a polyamide curing agent and accelerator. By employing the above technical solution, this invention constructs an organic-inorganic hybrid network, significantly improving the coating's salt spray resistance and UV aging resistance. Furthermore, through the in-situ generation of a silicon phosphate ceramic phase, it significantly enhances the structural integrity and long-term fire-retardant stability of the expanded carbonized layer.

Description

Technical Field

[0001] This invention relates to the field of functional coatings, and in particular to a weather-resistant and fire-retardant coating for ships based on polysiloxane modification. Background Technology

[0002] In the fields of modern marine transportation and offshore engineering, the safe operation of ships and their supporting facilities is not only the cornerstone of ensuring the stability of international trade chains, but also a crucial link in safeguarding national maritime rights and ecological security. Fire protection has always been a top priority in passive safety design during the design and operation of ships. Given that the hull structure operates in a closed and complex environment, in the event of a fire, the rapid conduction of heat between the metal bulkheads will lead to a rapid loss of structural strength, potentially resulting in a catastrophic accident. Therefore, the development and application of highly efficient marine fire-retardant coatings, which create a robust thermal barrier on the steel surface, has become a standard technical means to enhance the survivability of ships.

[0003] Most existing marine fire-retardant coatings employ an intumescent technology system. The core principle involves using organic polymers such as epoxy resin, acrylic resin, or chlorinated rubber as film-forming base materials, combined with a synergistic fire-retardant system consisting of a dehydrating charring agent, a charring catalyst, and a foaming agent. Under normal temperature conditions, these coatings provide basic physical protection and a decorative finish. However, in the event of a fire, the coating softens upon heating and rapidly expands under chemical reaction, forming a dense, charred insulating layer tens of times thicker than the original coating. This design effectively balanced coating thickness and fire-retardant efficiency in the early stages of technological development, providing a feasible path for initial fire protection of ship structures.

[0004] However, as global shipping expands into polar routes, high-temperature and high-humidity equatorial waters, and deep-sea areas, traditional organic fire-retardant coatings have gradually revealed profound inherent technical contradictions during long-term service. The primary contradiction lies in the conflict between the degradation of the base material caused by ultraviolet radiation and the time-dependent nature of fire-retardant performance. The marine atmosphere has extremely strong ultraviolet penetrating power, and the main chain structure of traditional organic resins is highly susceptible to photo-oxidation under prolonged sunlight, leading to breakage of polymer chains and uneven changes in cross-linking density. This microscopic degradation manifests macroscopically as powdering, cracking, and peeling of the coating, weakening its mechanical protection and, more seriously, disrupting the spatial uniformity of the fire-retardant system. Once the fire-retardant components are lost due to base material failure or their physical properties change, the coating will be unable to expand uniformly according to the preset mechanism in the event of a fire, resulting in structural defects in the charred layer and ultimately causing complete failure of fire protection. This "hidden loss" of fire-retardant performance induced by environmental aging is a fundamental bottleneck that existing technologies cannot solve through simple formula optimization.

[0005] Secondly, there is a deep trade-off between the high salt spray and high humidity characteristics of the marine environment and the long-term anti-corrosion performance of the coating. Chloride ions have extremely strong penetrating power, capable of reaching the surface of the metal substrate through the microporous structure of the coating, inducing severe electrochemical corrosion. Conventional fire-retardant coatings, in order to achieve a high expansion ratio, often need to maintain a low crosslinking density to allow volume expansion at high temperatures, but this inadvertently increases the permeability of the medium at room temperature. To enhance weather resistance and corrosion resistance, existing technologies usually attempt to introduce hydrophobic additives or add rust-inhibiting pigments, but this significantly alters the rheological properties of the coating and may even produce a negative synergistic effect with the fire-retardant system, leading to a decrease in the strength of the carbonized layer when heated, making it prone to detachment under intense hot air currents. The reason for this lies in the low chemical bond energy of traditional organic film-forming materials, making it difficult to maintain high flexibility and impermeability while also possessing excellent thermal stability. This trade-off in performance dimensions limits the overall service life of the coating under extreme sea conditions.

[0006] Furthermore, with the increasing demands for ship weight reduction and long-term maintenance, the comprehensive performance requirements for coatings have become increasingly stringent. How to construct a composite protective system that can resist oxidation and chain scission caused by strong ultraviolet radiation, effectively block salt spray penetration, and maintain efficient expansion and structural integrity under extreme fire conditions, without significantly increasing coating thickness and construction complexity, has become a major technical challenge in the field of marine coating engineering. Therefore, developing a novel fire-retardant coating based on polysiloxane modification, and addressing the fundamental incompatibility between weather resistance and fire resistance through the synergistic effect of an inorganic-organic hybrid structure, has become a key issue that urgently needs to be addressed by those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a weather-resistant and fire-retardant coating for ships based on polysiloxane modification, which solves the problems mentioned in the background art.

[0008] This invention is achieved by providing a marine weather-resistant and fire-retardant coating based on polysiloxane modification, comprising component A and component B in a mass ratio of 4:1 to 6:1. Component A comprises the following raw materials in parts by weight: 35 to 45 parts of polysiloxane-modified epoxy resin, 15 to 22 parts of microencapsulated ammonium polyphosphate, 8 to 12 parts of pentaerythritol, 6 to 10 parts of melamine, 3 to 5 parts of nano-sized titanium dioxide, 2 to 4 parts of aluminum silicate fiber, 1 to 2 parts of anti-settling agent, 0.5 to 1 part of defoamer, 0.5 to 1 part of leveling agent, and 10 to 15 parts of solvent. Component B consists of a polyamide curing agent and an accelerator in a mass ratio of 95:5.

[0009] In a preferred embodiment of the present invention, the preparation process of the polysiloxane-modified epoxy resin is as follows: Hydroxyl-terminated polydimethylsiloxane and bisphenol A type epoxy resin are placed in a reaction vessel, heated to 110°C to 120°C under nitrogen protection, and an organotin catalyst is added. The reaction is carried out for 4 to 6 hours until the epoxy value of the system reaches 0.38 to 0.42, forming a hybrid structure with a Si-O-Si main chain and epoxy side chains. The molecular weight of the hydroxyl-terminated polydimethylsiloxane is between 2000 and 5000, and the hydroxyl content is 1.5% to 2.5%. The epoxy equivalent of the bisphenol A type epoxy resin is 185 g / eq to 192 g / eq. By introducing high-bond-energy silicon-oxygen bonds into the epoxy resin main chain, the present invention constructs a film-forming base material with inherent UV radiation resistance properties. Since the bond energy of Si-O bonds is much higher than that of ultraviolet radiation, this base material can effectively resist photo-oxidation reactions in the marine atmosphere, eliminating the loss of fire-retardant components caused by base material degradation at the source.

[0010] Furthermore, the microencapsulated ammonium polyphosphate described in this invention uses melamine-formaldehyde resin as the coating material. The coating material accounts for 3% to 5% of the total mass of the microencapsulated ammonium polyphosphate, and its average particle size is controlled between 15 and 25 micrometers. Microencapsulation not only significantly improves the water dispersibility of ammonium polyphosphate in the coating, but more importantly, it forms a hydrophobic barrier on the coating surface, blocking the dissolution and loss of the fire-retardant active ingredients by moisture in a high-salt-spray environment, thus ensuring the stability of the fire-retardant performance of the coating after long-term service.

[0011] In a preferred embodiment of the present invention, the pentaerythritol, as a char-forming agent, has a purity of not less than 98% and a particle size distribution of 325 mesh to 400 mesh. The melamine, as a foaming agent, has a sublimation temperature that matches the dehydration temperature of the char-forming agent, ensuring that the gas generated under heating conditions can drive the molten base material to form a uniform honeycomb-like expansion structure.

[0012] Furthermore, the nano-sized titanium dioxide introduced in this invention not only provides hiding power as a pigment, but also acts synergistically with the polysiloxane material as a physical shielding agent. The nano-titanium dioxide is distributed in the micropores of the coating, enhancing the coating's ability to scatter and absorb ultraviolet light, further delaying the aging process of the polymer chain segments.

[0013] In a preferred embodiment of the present invention, the aluminosilicate fibers have an aspect ratio of 20:1 to 50:1 and a fiber diameter of 2 to 5 micrometers. During a fire, as the base material undergoes pyrolysis and expansion, the aluminosilicate fibers form a randomly arranged mesh-like skeleton within the carbonized layer. This fiber-reinforced structure effectively resists the erosion of intense hot air currents during a ship's cabin fire, preventing the expanded carbonized layer from cracking or partially detaching, thus maintaining the integrity of the thermal insulation barrier.

[0014] Furthermore, the manufacturing process of component A includes the following steps: First, the solvent is mixed with polysiloxane-modified epoxy resin and stirred for 20 minutes at a speed of 800 to 1000 rpm in a high-speed disperser to form a uniform base solution; then, microencapsulated ammonium polyphosphate, pentaerythritol, melamine, nano-sized titanium dioxide, and aluminum silicate fiber are added sequentially, and the speed is increased to 2500 to 3000 rpm for high-shear dispersion for 30 minutes; finally, anti-settling agent, defoamer, and leveling agent are added, the speed is reduced to 500 rpm, and the mixture is stirred for 15 minutes before grinding. The grinding process uses a horizontal sand mill, controlling the grinding fineness to be less than or equal to 40 micrometers. This precise particle size control ensures the leveling properties of the coating during application and allows the fire-retardant particles to achieve dense accumulation in the dry paint film, improving the water vapor barrier rate at room temperature.

[0015] As a preferred embodiment of the present invention, the weather-resistant and fire-retardant coating for ships described in the present invention, after being applied to the surface of the ship's steel, forms a coating with a tensile strength of not less than 5 MPa and an elongation at break of not less than 15% at room temperature. This enables the coating to adapt to the deformation of the substrate caused by mechanical vibration or thermal expansion and contraction during the ship's voyage, thus avoiding the formation of microcracks.

[0016] The technical solution of this invention constructs an organic-inorganic hybrid network within the coating by molecularly modifying epoxy resin with polysiloxane. This network structure exhibits extremely high density under normal temperature conditions, effectively blocking the penetration of chloride ions and water molecules, and its salt spray resistance time can exceed 1500 hours. Under high-temperature conditions such as fires, the polysiloxane component undergoes controlled thermal rearrangement in the initial heating stage, generating siloxane residues with high thermal stability. These residues react chemically with phosphoric acid substances produced by the thermal decomposition of ammonium polyphosphate, generating a silicon phosphate ceramic phase. This ceramic phase grows in situ on the pore walls of the expanded carbonized layer, significantly improving the fire resistance limit of the carbonized layer. Experimental data shows that the coating provided by this invention, with a thickness of 2.0 mm, can withstand fires for more than 120 minutes under a standard fiber-based fire curve.

[0017] Furthermore, the synergistic system employed in this invention exhibits excellent rheological compatibility during thermal expansion. The softening point of the polysiloxane-modified base material highly overlaps with the reaction temperature range of the fire retardant system. Within the critical temperature range of 300°C to 400°C, the base material maintains a suitable melt viscosity, ensuring that the gas can smoothly induce coating expansion while preventing cell coalescence or collapse due to excessively low viscosity. By adjusting the modification ratio of the polysiloxane, this invention achieves precise control over the expansion ratio between 20 and 40 times.

[0018] In a preferred embodiment of the present invention, the accelerator in component B is a tertiary amine compound, which, while ensuring a sufficient pot life after mixing components A and B, can guide the epoxy groups to fully crosslink with the polyamide under medium and low temperature conditions. This high crosslinking density further enhances the chemical stability of the coating in the high humidity and heat environment at sea, preventing the migration and precipitation of effective fire-retardant components.

[0019] Furthermore, the solvent described in this invention is composed of xylene and n-butanol in a mass ratio of 3:1. This mixed solvent system not only provides excellent solubility, ensuring that the molecular chains of the polysiloxane-modified epoxy resin can fully extend, but also prevents structural defects such as pinholes or bubbles from appearing in the coating during the drying process through a suitable volatilization gradient. Eliminating these microscopic defects is crucial for maintaining the long-term weather resistance and fire-retardant reliability of the coating.

[0020] In summary, this invention, through molecular design, combines a polysiloxane structure with excellent weather resistance with an epoxy resin possessing high film-forming properties, and integrates it with a surface-modified fire-retardant synergistic system to construct a complete protective logic suitable for extreme marine environments. This technical solution not only resolves the contradiction between UV degradation and salt spray penetration at the physical level, but also enhances the structural stability of the high-temperature insulation layer at the chemical level through the in-situ generation of a ceramic phase. This multi-dimensional synergistic effect enables the marine weather-resistant and fire-retardant coating described in this invention to achieve a fundamental breakthrough in comprehensive performance, providing long-term and reliable safety protection for ocean-going vessels and marine engineering equipment.

[0021] Furthermore, this invention strictly adheres to stoichiometric relationships when describing the coating component ratios. The molar ratio between the active epoxy groups in the polysiloxane-modified epoxy resin and the active hydrogen in the polyamide of component B is precisely calculated to ensure that there are no excess polar groups in the cured system. This design significantly reduces the water absorption rate of the coating, thereby preventing osmotic pressure damage induced by moisture accumulation within the coating.

[0022] In a preferred embodiment of the present invention, the surface of the nano-sized titanium dioxide is treated with an inorganic coating of aluminum and silicon. This treatment not only suppresses the catalytic activity that titanium dioxide may generate under ultraviolet light, preventing secondary degradation of the surrounding resin matrix, but also improves its wettability in the polysiloxane-modified base material, ensuring that the pigment particles can be uniformly anchored in the polymer network.

[0023] Furthermore, this invention systematically optimizes the application thickness and interlayer adhesion of the fire-retardant coating. By introducing aluminum silicate fibers with a specific aspect ratio, the coating does not sag even when a single spray thickness reaches 1.0 mm. During multi-layer application, due to the excellent recoatability of the polysiloxane-modified resin, the layers form a unified whole through chemical bonding and physical interlocking, eliminating the risk of interlayer delamination. This provides crucial mechanical stability for ship structures subjected to severe rocking and impact.

[0024] In a preferred embodiment of the present invention, the fire-retardant coating of the present invention has a char residue rate (at 800 degrees Celsius) of not less than 45% during the carbonization process. A high char residue rate means that in the later stages of a fire, the coating can transform into a denser inorganic insulation layer. This transformation from organic to inorganic is the intrinsic physical mechanism by which the present invention achieves an ultra-long fire resistance time. The silicon element in the polysiloxane acts as a connecting bridge in this transformation process; by forming a stable inorganic framework, it blocks the path of heat conduction to the steel substrate.

[0025] Furthermore, the anti-settling agent described in this invention is organically modified bentonite, which effectively prevents the stratification and sedimentation of high-density fire-retardant particles (such as titanium dioxide and microencapsulated ammonium polyphosphate) during storage by constructing a thixotropic network in the coating system. Maintaining this characteristic ensures that the concentration of the fire-retardant component remains consistent throughout the coating application, whether at the bottom or top of the container, thus guaranteeing the uniformity of fire-retardant performance across the entire area after construction.

[0026] In a preferred embodiment of the present invention, the leveling agent is a polyether-modified organosiloxane. This type of leveling agent not only significantly reduces the surface tension of the coating, promoting wetting and spreading of the paint film on rough steel surfaces, but also oriented itself on the paint film surface, forming a thin, silicon-rich layer. This silicon-rich layer, acting as the first line of defense, greatly enhances the coating's initial resistance to water staining and its hydrophobic properties, further shielding it from the intrusion of corrosive media in the marine atmosphere.

[0027] Furthermore, this invention sets forth specific requirements for the production environment of the coating, namely, the production process must be carried out under conditions of ambient humidity less than 75% to prevent hygroscopic components such as microencapsulated ammonium polyphosphate from introducing moisture during processing, thereby affecting the electrical insulation performance and anti-corrosion effect after film formation. In the packaging and storage stages, both component A and component B are sealed in metal drums and filled with dry nitrogen for top protection to ensure that the chemical activity and physical properties of the product remain unchanged within its 12-month shelf life.

[0028] In a preferred embodiment of the present invention, the marine weather-resistant and fire-retardant coating of the present invention requires the steel substrate to be sandblasted to Sa2.5 grade before application, and an epoxy zinc-rich primer is applied in conjunction. The coating of the present invention and the epoxy zinc-rich primer have excellent chemical compatibility, and the interfacial bonding force between the two is strengthened through the interpenetration of polar groups, ensuring that no interfacial delamination occurs under long-term salt spray environment.

[0029] Furthermore, the technical solution described in this invention exhibits a significant stepwise nature in its thermal response mechanism. In the initial heating stage (100-200 degrees Celsius), the residual light components in the defoamer and leveling agent escape smoothly without compromising the integrity of the coating film. At 200-300 degrees Celsius, the microcapsule wall material ruptures, and ammonium polyphosphate begins to decompose, releasing phosphoric acid, inducing pentaerythritol esterification and dehydration. At 300-500 degrees Celsius, melamine sublimates to generate nitrogen gas, driving the paint film to expand to a predetermined multiple, while polysiloxanes undergo thermal rearrangement to form an initial inorganic framework. Above 500 degrees Celsius, the aluminosilicate fibers and the generated ceramic phase work synergistically to solidify the expanded structure, entering the long-term thermal insulation stage. This multi-level response mechanism design enables the coating to readily cope with various fire scenarios, from smoldering to intense combustion.

[0030] In a preferred embodiment of the present invention, the volatile organic compound (VOC) content of the coating is strictly controlled below 250 g / L, complying with the relevant standards of the International Maritime Organization (IMO) regarding the environmental performance of marine coatings. This not only protects the occupational health of construction workers but also aligns with the development trend of green shipping.

[0031] Furthermore, this invention achieves the maintenance of coating toughness in ultra-low temperature (-40 degrees Celsius) environments through precise control of the molecular chain segments of polysiloxane-modified epoxy resin. Ships serving on polar routes frequently face extreme diurnal temperature variations and the pressure of ice collisions. The low-temperature embrittlement point of the coating described in this invention is far lower than that of similar organic fire-retardant coatings, enabling the paint film to remain crack-free and leak-free under frigid conditions, ensuring all-weather, all-terrain fire safety.

[0032] In a preferred embodiment of the present invention, the coating described herein, after 2000 hours of continuous irradiation in a simulated solar aging test (QUV test), exhibits a color difference change ΔE of less than 3.0, a gloss retention rate exceeding 80%, and a fire resistance performance degradation rate controlled within 5%. This data strongly demonstrates the significant advantages of polysiloxane modification technology in improving the weather resistance of fire-retardant coatings.

[0033] Furthermore, the fire-retardant coating system provided by this invention is not only suitable for conventional ship types such as bulk carriers and oil tankers, but also particularly suitable for special fields with extremely high fire resistance requirements, such as liquefied natural gas (LNG) carriers and offshore platforms. Because the carbonized layer it forms has extremely high thermal resistance, it can effectively delay the time it takes for structural steel to heat up to the critical temperature (540 degrees Celsius), buying valuable time for personnel evacuation and fire fighting.

[0034] In a preferred embodiment of the present invention, the mixture of component A and component B has a pot life of no less than 4 hours at 25 degrees Celsius. This provides ample operating window for large-area mechanized spraying of large ship surfaces, avoiding clogging of spraying equipment and construction quality defects caused by excessively rapid gelation of the coating.

[0035] Furthermore, this invention designs the hardness of the cured coating to reach 2H to 3H (pencil hardness). This hardness level ensures that the coating has good scratch and mechanical wear resistance in daily operation, while retaining sufficient flexibility to prevent brittle fracture. This balance between hardness and toughness is achieved through a scientific ratio of flexible polysiloxane segments to the rigid epoxy resin structure.

[0036] In a preferred embodiment of the present invention, the weather-resistant and fire-retardant coating for ships described herein has a thermal conductivity of the carbonized layer as low as 0.05 W / (m·K) to 0.08 W / (m·K) at 1000 degrees Celsius. This extremely low thermal conductivity is attributed to the combined contribution of the honeycomb microporous structure and the silicate phosphate ceramic phase, which effectively cuts off the paths of high-temperature heat radiation and heat conduction.

[0037] Furthermore, in the solvent system described in this invention, the use of n-butanol not only plays a role in adjusting viscosity, but also acts as a co-solvent to improve the compatibility of components A and B after mixing, preventing the "sweating" phenomenon caused by phase separation during the curing process, thereby ensuring the smoothness and aesthetics of the coating surface.

[0038] In a preferred embodiment of the present invention, the rust-preventive pigments containing heavy metals such as lead and chromium are excluded from the selection of raw materials. The nano-titanium dioxide and aluminum silicate fibers used are both chemically inert and environmentally friendly materials. This ensures that the coating does not produce toxic or harmful fumes during high-temperature decomposition, further improving the quality of the survival environment at fire scenes.

[0039] Furthermore, in the preparation process of the polysiloxane-modified epoxy resin described in this invention, a small amount of siloxane alkoxy groups (Si-OR) are retained by controlling the reaction endpoint. These residual active groups can undergo a slow hydrolysis-condensation reaction with trace amounts of moisture in the air during long-term service after coating application, producing a secondary cross-linking effect. This "self-healing" cross-linking reinforcement mechanism further compensates for the potential loss of microscopic properties due to long-term aging, extending the effective protective life of the coating.

[0040] In a preferred embodiment of the present invention, the fire-retardant coating described herein maintains an adhesion of level 2 or higher to steel after undergoing 20 thermal cycles (-40 degrees Celsius to 60 degrees Celsius) (pull-off test). This exceptional environmental adaptability makes it an ideal choice for ships navigating across dimensions.

[0041] Furthermore, the dispersion of the aluminosilicate fibers in component A according to the present invention is achieved through a stepwise feeding process. First, the short fibers are premixed with a portion of the base material to form a paste, which is then added to the main reaction vessel for dispersion. This process effectively avoids excessive fiber breakage during high-speed shearing, preserving the necessary aspect ratio required for the fiber-reinforced carbonized layer.

[0042] In a preferred embodiment of the present invention, the coating is prepared using an online particle size monitoring system to ensure that the particle size distribution of all solid powders exhibits a bimodal distribution. Large-diameter functional particles serve as a filling framework, while small-diameter nanoparticles fill the gaps. This tightly packed structure significantly extends the "tortuous path" of corrosive media penetration at the microscopic level, thereby achieving excellent anti-corrosion performance through physical shielding without relying on large amounts of chemical preservatives.

[0043] Furthermore, the defoamer described in this invention is a polymer-based defoamer that does not contain silicone oil. This choice is to avoid the risk of pinholes in the paint film that may be caused by traditional silicone defoamers, ensuring the surface film quality of the coating during large-area construction, and avoiding localized corrosion and fire-resistant weaknesses caused by paint film defects.

[0044] As a preferred embodiment of the present invention, the marine weather-resistant fire-retardant coating of the present invention has a higher specific strength (strength / density) of its intumescent carbonized layer than traditional phosphorus-nitrogen fire-retardant coatings. This means that, under the same heat insulation effect, the carbonized layer formed by the present invention is lighter and stronger, which has positive engineering significance for reducing the weight of the ship's superstructure and improving the stability of the center of gravity.

[0045] Furthermore, the technical solution described in this invention achieves its effect by strictly controlling the dehydration temperature range of pentaerythritol, thus aligning it with the thermal rearrangement temperature of polysiloxanes. At approximately 400 degrees Celsius, the carbonized skeleton produced by the dehydration of pentaerythritol is precisely encapsulated by the siloxane network formed by the rearrangement. This microscopic "interpenetrating network" effect is the fundamental reason why the carbonized layer of this invention exhibits extremely strong thermal shock resistance.

[0046] In a preferred embodiment of the present invention, the solvent recovery rate of the coating used in the production process can reach over 90%. The use of fully enclosed milling and mixing equipment not only reduces VOC emissions during production but also lowers production costs.

[0047] Furthermore, this invention calibrates the spraying process parameters for weather-resistant and fire-retardant coatings for marine applications. High-pressure airless spraying equipment is recommended, with the spraying pressure controlled between 15 MPa and 20 MPa, and the nozzle diameter between 0.021 inches and 0.025 inches. Under these parameters, the coating achieves optimal atomization and film density, and the aluminosilicate fibers tend to be arranged parallel to the substrate surface, which is beneficial for improving the lateral continuity of the carbonized layer.

[0048] In a preferred embodiment of the present invention, the fire-retardant coating of the present invention has a base resin with a molecular weight distribution index (PDI) controlled between 2.0 and 2.5. This narrow molecular weight distribution ensures stable rheological behavior of the resin, exhibiting excellent process consistency during application and curing, and avoiding fluctuations in film performance caused by differences in molecular weight.

[0049] Furthermore, the polyamide curing agent described in this invention is a low molecular weight polyamide modified with dimer acid. This curing agent has good flexibility and hydrophobicity, and when mixed with polysiloxane-modified epoxy resin, it can form a cross-linked network with certain damping properties. This network structure can effectively absorb structural noise and high-frequency vibration energy generated by ships during navigation, providing fire protection while also playing a certain role in vibration reduction and noise reduction.

[0050] As a preferred embodiment of the present invention, the marine weather-resistant and fire-retardant coating of the present invention, after application and complete curing, exhibits low surface energy and certain anti-marine biofouling properties. Although its main functions are fire resistance and weather resistance, this additional low surface energy characteristic can reduce dirt accumulation on the hull surface, indirectly reducing the ship's navigation resistance.

[0051] Furthermore, the fire-retardant coating system described in this invention fully considers the influence of temperature differences in different sea areas in its formulation design. By adjusting the ratio of xylene to n-butanol in the solvent, a constant application viscosity can be achieved under different climatic conditions from tropical to frigid zones, ensuring the global applicability of this technical solution.

[0052] In a preferred embodiment of the present invention, the fire-retardant coating of the present invention, after undergoing a high-pressure water scouring test (pressure 10 MPa), maintains an intact paint film with no significant decrease in adhesion. This characteristic ensures that the fire-retardant layer is not damaged during routine maintenance and high-pressure water cleaning operations on the ship.

[0053] Furthermore, in describing the technical solution of this invention, the settings of all components and process parameters are based on extensive engineering verification. For example, if the amount of aluminosilicate fiber added is less than 2 parts, the resistance of the carbonized layer to airflow erosion will decrease significantly; if it is more than 4 parts, the viscosity of the coating will be too high, affecting the spraying atomization effect. This invention achieves an optimal balance of various performance indicators through precise component ratios.

[0054] In a preferred embodiment of the present invention, the mass fraction of Si-O-Si segments in the polysiloxane-modified epoxy resin is controlled between 15% and 25%. This range ensures sufficient weather resistance and thermal stability, while also ensuring good compatibility between the base material and organic pigments, fillers, and fire retardants, thus avoiding phase separation or bleeding phenomena in the coating caused by excessive differences in component polarity.

[0055] Furthermore, the coating system described in this invention does not produce acidic products that induce metal corrosion during the curing process. This is of profound significance for protecting ship hull steel plates and extending the service life of ships.

[0056] In summary, the polysiloxane-modified marine weather-resistant fire-retardant coating of this invention, through the integrated application of chemical modification of the base resin, microencapsulation protection of the fire-retardant system, and fiber reinforcement technology, completely solves the industry problems of unreliable performance, short lifespan, and easy failure of traditional fire-retardant coatings in complex marine environments. Its defined chemical composition, rigorous manufacturing process, and scientific protection logic together constitute a system-level, highly reliable passive fire protection technology solution for ships. All technical features are based on objective facts, eliminating uncertainties and ensuring a high degree of certainty and repeatability in practical engineering applications. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the preparation process of component A in this invention; Figure 2 This is a schematic diagram of the structure after the coating of the present invention is applied to the surface of steel.

[0058] The attached figures are labeled as follows: 1. Steel substrate; 2. Epoxy zinc-rich primer; 3. Weather-resistant and fire-retardant coating layer; 4. Polysiloxane-modified epoxy resin; 5. Microencapsulated ammonium polyphosphate; 6. Aluminum silicate fiber; 7. Nano-sized titanium dioxide. Detailed Implementation

[0059] The implementation of a polysiloxane-modified marine weather-resistant fire-retardant coating involves complex material chemical synthesis, multiphase dispersion process, and precise engineering construction calibration. In order to enable engineers in the art to fully and accurately reproduce the technical solution of this invention, the following will provide a detailed description from multiple dimensions such as base material synthesis, component ratio, manufacturing process, thermal response mechanism, and engineering application performance.

[0060] In the technical solution of this invention, a weather-resistant and fire-retardant coating for ships based on polysiloxane modification is composed of component A and component B in a mass ratio of 4:1 to 6:1. Component A, as the main functional carrier system of the coating, has undergone rigorous engineering calculations and experimental verification in terms of its composition and mass percentages. Specifically, it includes 35 to 45 parts of polysiloxane-modified epoxy resin, 15 to 22 parts of microencapsulated ammonium polyphosphate, 8 to 12 parts of pentaerythritol, 6 to 10 parts of melamine, 3 to 5 parts of nano-sized titanium dioxide, 2 to 4 parts of aluminum silicate fiber, 1 to 2 parts of organically modified bentonite anti-settling agent, 0.5 to 1 part of non-silicone polymer defoamer, 0.5 to 1 part of polyether-modified organosiloxane leveling agent, and 10 to 15 parts of a solvent composed of xylene and n-butanol. Component B, as the curing system, consists of a polyamide curing agent and a tertiary amine accelerator, with a fixed mass ratio of 95:5.

[0061] The polysiloxane-modified epoxy resin, which is the core competitive advantage of this invention, is prepared through a typical organic-inorganic molecular hybridization process. In specific engineering implementation, hydroxyl-terminated polydimethylsiloxane and bisphenol A type epoxy resin are first placed in a reactor equipped with an anchor stirrer, a reflux condenser, and a nitrogen purging system according to a preset ratio. The molecular weight distribution of the hydroxyl-terminated polydimethylsiloxane is strictly controlled between 2000 and 5000, and its hydroxyl content is within the range of 1.5% to 2.5%. This parameter selection ensures that it has appropriate reactivity and compatibility with the epoxy resin. The selected bisphenol A type epoxy resin has an epoxy equivalent of 185 g / eq to 192 g / eq and a low initial viscosity, which is beneficial for subsequent modification reactions. Under nitrogen protection, the system is gradually heated to 110°C to 120°C, and then an organotin compound is added as a catalyst. The reaction process lasts 4 to 6 hours, during which the epoxy value of the system is monitored in real time by chemical titration until it reaches a predetermined range of 0.38 to 0.42. At this point, the terminal hydroxyl groups undergo a condensation reaction with some of the active groups in the epoxy resin, forming a hybrid structure with a Si-O-Si backbone and epoxy side chains. This structure introduces the high bond energy of silicon-oxygen bonds into the epoxy framework at the molecular level. Since the bond energy of the Si-O bond is much higher than that of ultraviolet radiation, this base resin exhibits excellent resistance to photo-oxidative degradation in marine atmospheric environments.

[0062] Furthermore, this invention modifies the core component of the fire-retardant system, ammonium polyphosphate, through microencapsulation. The microencapsulated ammonium polyphosphate uses melamine-formaldehyde resin as the coating material, chosen for its excellent chemical stability and thermal decomposition characteristics. The coating material accounts for 3% to 5% of the total mass of the microencapsulated ammonium polyphosphate, and its average particle size is precisely controlled between 15 and 25 micrometers. Microstructurally, the melamine-formaldehyde resin forms a dense hydrophobic protective layer on the surface of the ammonium polyphosphate particles. This not only significantly improves the wettability and dispersibility of ammonium polyphosphate in non-polar polysiloxane-modified epoxy resin, but more importantly, this protective layer effectively blocks the dissolution of phosphate components by moisture in high-salt-spray environments. Experimental observations show that unmodified ammonium polyphosphate is prone to precipitation and loss in simulated marine environments, while the microencapsulation structure used in this invention ensures the in-situ stability of the fire-retardant component during long-term service.

[0063] Pentaerythritol, as a char-forming agent, has a significant impact on the quality of the expanded char layer due to its physical properties. In a preferred embodiment of the present invention, the purity of pentaerythritol is not less than 98%, and its particle size distribution is between 325 mesh and 400 mesh. This fine and uniform particle size distribution ensures that, under heating conditions, pentaerythritol can undergo a sufficient esterification reaction with the phosphoric acid substances released from the decomposition of ammonium polyphosphate, thereby generating a continuous char precursor in a very short time. Melamine, used in conjunction with pentaerythritol as a foaming agent, has a sublimation temperature range that closely matches the dehydration temperature of pentaerythritol. This ensures that the nitrogen gas generated during heating can uniformly and controllably drive the molten base material to form a dense honeycomb expanded structure.

[0064] Furthermore, the nano-sized titanium dioxide introduced in this invention possesses dual functional properties. Its surface undergoes an aluminum and silicon inorganic coating treatment, which suppresses the photocatalytic activity that titanium dioxide may exhibit under ultraviolet light, thereby preventing secondary damage to the surrounding polysiloxane-modified resin chains. The nano-sized titanium dioxide particles are uniformly distributed in the micropores of the coating through high-shear dispersion, utilizing their extremely large specific surface area to scatter and absorb ultraviolet light, forming a synergistic anti-aging mechanism with the polysiloxane-modified material. Simultaneously, these nanoparticles can penetrate the charred layer in the later stages of a fire, playing a role in physical reinforcement.

[0065] In terms of mechanical reinforcement, the aluminosilicate fibers selected in this invention exhibit a crucial skeletal support role. The aspect ratio of these fibers is set to 20:1 to 50:1, and the fiber diameter is in the micron range of 2 to 5 micrometers. During the dispersion stage of coating production, specific processes prevent excessive fiber breakage, preserving their aspect ratio advantage. When a fire occurs and the coating undergoes violent pyrolysis and expansion, these aluminosilicate fibers construct a randomly arranged three-dimensional network skeleton within the expanded carbonized layer. This fiber-reinforced structure significantly improves the structural integrity of the carbonized layer, enabling it to withstand the scouring of hot air currents with velocities exceeding 10 meters per second, common in ship cabin fires, and preventing localized collapse or complete detachment of the insulation layer.

[0066] The manufacturing process of component A reflects the meticulous control logic at the chief engineer level. First, a mixed solvent of xylene and n-butanol in a 3:1 mass ratio is added to a high-speed dispersion tank along with pre-prepared polysiloxane-modified epoxy resin. The mixture is stirred at 800-1000 rpm for 20 minutes until a semi-transparent and homogeneous base solution is formed. Then, microencapsulated ammonium polyphosphate, pentaerythritol, melamine, nano-sized titanium dioxide, and premixed aluminum silicate fiber paste are added slowly in sequence. At this point, the stirring speed is increased to 2500-3000 rpm for high-shear dispersion for 30 minutes, using high-energy shear force to break up pigment and filler agglomerates. Finally, anti-settling agent, defoamer, and leveling agent are added, and the stirring speed is reduced to 500 rpm for 15 minutes at a constant speed. After mixing, the slurry enters a horizontal sand mill, using zirconia beads with a diameter of 0.8-1.2 mm as the grinding media, controlling the fineness of the outlet material to be less than or equal to 40 micrometers. This stringent particle size control ensures that the coating has good rheological properties during spraying and allows the fire-retardant particles to achieve dense deposition in the dry paint film.

[0067] Component B of this invention is designed with the special characteristics of the marine environment in mind. The dimer acid-modified low molecular weight polyamide curing agent used imparts excellent flexibility and hydrophobic properties to the coating. The addition of tertiary amine accelerators ensures that the system can achieve full cross-linking in a wide temperature range from 5°C to 35°C. In the cross-linked network formed after curing, the molar ratio between active epoxy groups and active hydrogen in the polyamide is precisely calculated (usually close to 1:1), resulting in very few residual polar groups inside the paint film, thereby significantly reducing the water absorption rate of the coating. Its water vapor barrier at room temperature is more than 40% higher than that of traditional epoxy coatings.

[0068] At the engineering application level, this invention systematically optimizes the coating application logic. Before application, the steel surface of the ship hull must be sandblasted to Sa2.5 grade, and a 40-60 micrometer thick epoxy zinc-rich primer should be applied. The fire-retardant coating described in this invention exhibits excellent interfacial compatibility with the epoxy zinc-rich primer. During spraying, it is recommended to use a high-pressure airless spraying device with a spraying pressure of 15 MPa to 20 MPa and a nozzle diameter of 0.021 inches to 0.025 inches. Under these process parameters, the aluminosilicate fibers tend to align parallel to the substrate surface, which not only increases the thickness of a single spray (up to 1.0 mm without sagging) but also lays the foundation for the lateral continuity of the carbonized layer.

[0069] The fire-retardant mechanism of this invention exhibits a significant stepped thermal response characteristic. When the ambient temperature rises to 100-200 degrees Celsius, the coating enters a preheating period, and the trace amounts of solvent remaining inside escape steadily. When the temperature rises to 200-300 degrees Celsius, the microcapsule wall material ruptures, and ammonium polyphosphate begins to decompose and release phosphoric acid, inducing pentaerythritol to undergo an esterification reaction. In the core range of 300-500 degrees Celsius, melamine sublimates in large quantities, generating a gas source that drives the paint film to expand rapidly. At the same time, the polysiloxane components undergo controlled thermal rearrangement, generating highly thermally stable siloxane residues. When the temperature exceeds 500 degrees Celsius, the siloxane residues undergo an in-situ chemical reaction with phosphate substances to generate a silicon phosphate ceramic phase. This ceramic phase is solidified on the pore walls of the expanded carbonized layer, and combined with the support of aluminosilicate fibers, forms a long-lasting thermal insulation barrier with an extremely low thermal conductivity (as low as 0.05 W / (m·K) at 1000 degrees Celsius).

[0070] To further verify the superiority of the technical solution of the present invention, specific embodiments and comparative examples are given below, and a detailed data comparison is conducted.

[0071] In Example 1, the formulation of component A was set as follows: 40 parts of polysiloxane-modified epoxy resin (epoxy value 0.40), 18 parts of microencapsulated ammonium polyphosphate, 10 parts of pentaerythritol, 8 parts of melamine, 4 parts of nano-titanium dioxide, 3 parts of aluminum silicate fiber, 1.5 parts of organically modified bentonite, 0.7 parts of non-silicone defoamer, 0.8 parts of polyether-modified silicone leveling agent, and 14 parts of mixed solvent. The mixing ratio of component B to component A was 1:5.

[0072] In Example 2, the formulation of component A was set as follows: 35 parts polysiloxane-modified epoxy resin, 22 parts microencapsulated ammonium polyphosphate, 12 parts pentaerythritol, 10 parts melamine, 5 parts nano titanium dioxide, 4 parts aluminum silicate fiber, 2 parts organically modified bentonite, 1 part non-silicone defoamer, 1 part leveling agent, and 8 parts mixed solvent. The mixing ratio of component B to component A was 1:4.

[0073] In Example 3, the formulation of component A was set as follows: 45 parts polysiloxane-modified epoxy resin, 15 parts microencapsulated ammonium polyphosphate, 8 parts pentaerythritol, 6 parts melamine, 3 parts nano-titanium dioxide, 2 parts aluminum silicate fiber, 1 part organically modified bentonite, 0.5 parts defoamer, 0.5 parts leveling agent, and 19 parts mixed solvent. The mixing ratio of component B to component A was 1:6.

[0074] In comparison, Comparative Example 1 used standard bisphenol A type epoxy resin without polysiloxane modification as the base material, and the remaining fire-retardant components and additives were completely consistent with those of Example 1. Comparative Example 2 used the base material of Example 1, but the ammonium polyphosphate was not microencapsulated. Comparative Example 3 used the base material of Example 1, but without the addition of aluminum silicate fiber.

[0075] For the above embodiments and comparative examples, comprehensive performance tests were conducted according to relevant international standards (such as IMO FTP Code and relevant ISO standards), and the test results are summarized in Table 1. The total coating thickness of all test samples was controlled within 2.0 mm (±0.1 mm).

[0076] Table 1: Comparison of performance test data between embodiments of the present invention and comparative examples

[0077] In-depth engineering analysis of the data in Table 1 reveals that the technical solution described in this invention exhibits significant advantages in all key performance indicators. Firstly, regarding refractory time, Examples 1-3 consistently maintained a refractory time of over 120 minutes at a thickness of 2.0 mm, with a maximum of 142 minutes, while Comparative Example 1, using ordinary epoxy resin, only achieved 85 minutes. This fully demonstrates the significant contribution of the polysiloxane-modified base material to the stability of the silica-phosphate ceramic layer formed at high temperatures, relative to the carbonized layer.

[0078] Regarding weather resistance, Example 1 exhibited a color difference change (ΔE) of only 1.8, and its fire resistance retention rate after aging reached 98%, far superior to Comparative Examples 1 and 2. This directly confirms the immune effect against UV degradation after the Si-O bond is introduced into the resin backbone, as well as the protective effect of microencapsulation technology on the effective fire-retardant components. Comparative Example 2, lacking encapsulation of ammonium polyphosphate, showed a significant decrease in fire resistance after salt spray and aging tests, demonstrating the necessity of microencapsulation in marine environments.

[0079] From a physical and mechanical property analysis, the elongation at break of all embodiments of the present invention is not less than 15%, significantly higher than 8% of Comparative Example 1. This improved flexibility allows the coating to effectively absorb mechanical vibration stress and thermal stress during ship navigation, preventing the formation of microcracks and thus eliminating the penetration channels of corrosive media at the source. Adhesion test results show that the embodiments maintain extremely high bonding strength even after multiple thermal cycles, thanks to the excellent chemical bonding formed between the polysiloxane-modified resin and the substrate and primer.

[0080] The comparison of the structural stability of the carbonized layer further highlights the value of aluminosilicate fibers. The example performed well in the simulated hot airflow scouring test, while Comparative Example 3, lacking fiber reinforcement, showed significant localized collapse, and its fire resistance time was shortened by 43 minutes compared to Example 1. This demonstrates that in real fire environments, the mechanical strength and thermal insulation performance of the carbonized layer are equally important. This invention achieves a qualitative leap in the performance of the carbonized layer through the synergy of the fiber skeleton and the hybrid matrix.

[0081] Furthermore, the present invention's requirements for humidity control in the coating production environment (less than 75%) and nitrogen-filled protection during packaging ensure the activity of hygroscopic components such as microencapsulated ammonium polyphosphate. In long-term storage stability tests, after 12 months of sealed packaging, component A showed a viscosity change rate of less than 5%, and no obvious pigment stratification or clumping was observed. This is attributed to the stable thixotropic network constructed by the organically modified bentonite.

[0082] The marine weather-resistant and fire-retardant coating described in this invention not only achieves breakthroughs in physical and chemical properties but also takes into full consideration the ease of application. The pot life of the mixed components A and B is no less than 4 hours at 25 degrees Celsius, a long window that significantly reduces the difficulty of large-area spraying. Simultaneously, because the VOC content in the system is controlled below 250 g / L and it contains no lead, chromium, or other heavy metals or halogen flame retardants, the toxicity of the fumes generated during the high-temperature pyrolysis process is extremely low, fully meeting the stringent requirements for green shipping and personal safety.

[0083] In extreme low-temperature environments such as polar routes, the coating described in this invention, through the regulating effect of the flexible segments of polysiloxane, lowers its low-temperature embrittlement point to below -45 degrees Celsius, effectively preventing paint film cracking caused by the drastic contraction of the ship's steel plates during voyages at extremely high latitudes. This all-weather service capability is unmatched by traditional pure organic fire-retardant coatings.

[0084] Furthermore, the small amount of siloxane alkoxy groups (Si-OR) retained in the molecular design of this invention can undergo a slow hydrolysis-condensation reaction with trace amounts of moisture penetrating from the air during long-term service after the coating film has cured, forming localized secondary crosslinks. This unique self-healing crosslinking mechanism manifests macroscopically as the coating hardness and corrosion resistance remaining stable over time, offsetting performance losses caused by environmental aging, thereby extending the effective maintenance cycle of the coating to 8-10 years.

[0085] In summary, this invention, through the deep integration of polysiloxane molecular modification technology, microencapsulation technology, fiber reinforcement technology, and precise solvent gradient control technology, constructs a highly deterministic passive fire protection system in marine environments. From the microscopic synthesis of the base material to the macroscopic application of the coating, the selection of every technical parameter is based on detailed engineering data and physicochemical principles. The embodiments and comparative data provided by this invention clearly outline the synergistic relationship between the components, demonstrating the superior effectiveness of this technical solution in addressing industry pain points such as poor weather resistance, easy peeling of the carbonized layer, and short anti-corrosion life of marine fire-retardant coatings. The successful implementation of this coating will provide a more reliable and long-lasting fire safety barrier for various ocean-going vessels, marine engineering platforms, and LNG carriers.

[0086] It is particularly important to note that the present invention allows for a certain tolerance range in setting process parameters. For example, although the recommended ratio of components A to B is 5:1, when it fluctuates within the range of 4:1 to 6:1, the paint film performance that meets basic engineering requirements can still be obtained by adjusting the amount of accelerator. This process tolerance enhances its applicability in actual construction sites. Furthermore, although the manufacturing process described in this invention employs high-energy equipment such as horizontal sand mills, its solvent recovery rate and energy consumption control during production have reached the advanced level of modern chemical production.

[0087] For those skilled in the art, based on the detailed embodiments described above, the proportions of some components can be fine-tuned according to specific ship navigation areas or special structural design requirements without departing from the core technical concept of this invention. For example, when targeting ships in equatorial waters exposed to high ultraviolet radiation year-round, the modified proportions of nano-titanium dioxide and polysiloxane can be appropriately increased; while for highly corrosive industrial transport ships, the crosslinking density of the curing agent can be further optimized. These reasonable extensions and evolutions based on the technical framework of this invention should all be considered part of the scope of protection of this invention.

[0088] In the final product, the coating described in this invention exhibits a pencil hardness of 2H to 3H. This balance between hardness and flexibility ensures that the fire-resistant layer remains intact even when subjected to deck machinery impacts or cargo handling friction. Its low surface energy also unexpectedly endows the coating with a certain degree of self-cleaning ability, reducing the accumulation of salt and dirt. This is also of positive engineering significance for maintaining the cleanliness of the ship's appearance and reducing long-term maintenance costs. Through this comprehensive and multi-dimensional technical solution, this invention establishes a new technological benchmark in the field of marine protective coatings.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A weather-resistant and fire-retardant coating for ships based on polysiloxane modification, characterized in that, The weather-resistant and fire-retardant coating for ships is composed of component A and component B in a mass ratio of 4:1 to 6:1; component A includes the following raw materials by weight: 35 to 45 parts of polysiloxane-modified epoxy resin (4); 15 to 22 parts of microencapsulated ammonium polyphosphate (5); 8 to 12 parts of pentaerythritol; 6 to 10 parts of melamine; 3 to 5 parts of nano-sized titanium dioxide (7); and 2 to 4 parts of aluminum silicate fiber (6). The composition includes 1 to 2 parts of organic modified bentonite antisettling agent; 0.5 to 1 part of non-silicone polymer defoamer; 0.5 to 1 part of polyether modified organosiloxane leveling agent; 10 to 15 parts of solvent, wherein the solvent is composed of xylene and n-butanol in a mass ratio of 3:1; and component B is composed of polyamide curing agent and tertiary amine accelerator, wherein the mass ratio of polyamide curing agent to tertiary amine accelerator is 95:

5.

2. The marine weather-resistant and fire-retardant coating based on polysiloxane modification according to claim 1, characterized in that, The polysiloxane-modified epoxy resin (4) has an organic-inorganic hybrid structure composed of a Si-O-Si main chain and epoxy side chains, and its preparation raw materials and process are as follows: Hydroxyl-terminated polydimethylsiloxane with a molecular weight distribution between 2000 and 5000 and a hydroxyl content of 1.5% to 2.5% is reacted with bisphenol A type epoxy resin with an epoxy equivalent of 185 g / eq to 192 g / eq as reactants, and the reaction is carried out at a temperature of 110°C to 120°C for 4 to 6 hours under nitrogen protection and with the action of an organotin catalyst; the reaction is controlled to achieve the desired effect. The epoxy value of the system reaches 0.38 to 0.42, thereby introducing high bond energy silicon-oxygen bonds into the epoxy resin backbone and retaining a small amount of siloxane alkoxy groups in the molecular chain segments, so that the weather-resistant and fire-retardant coating layer (3) for ships can undergo hydrolysis and condensation reaction with moisture in the air during the curing and service process, forming a self-healing secondary crosslinking reinforcement mechanism; in the polysiloxane modified epoxy resin (4), the mass fraction of Si-O-Si chain segments is 15% to 25%, and the molecular weight distribution index (PDI) of the polysiloxane modified epoxy resin (4) is controlled between 2.0 and 2.

5.

3. The marine weather-resistant and fire-retardant coating based on polysiloxane modification according to claim 1, characterized in that, The microencapsulated ammonium polyphosphate (5) uses melamine-formaldehyde resin as the coating wall material. The mass of the coating wall material accounts for 3% to 5% of the total mass of the microencapsulated ammonium polyphosphate (5), and its average particle size is controlled between 15 micrometers and 25 micrometers. The purpose is to build a hydrophobic barrier inside the coating to block the dissolution of the active ingredients by water under salt spray environment. The pentaerythritol is used as a char-forming agent. Its purity is not less than 98%, and its particle size distribution is between 325 mesh and 400 mesh. The melamine is used as a foaming agent. Its sublimation temperature matches the dehydration temperature of the pentaerythritol. The dehydration temperature range of the pentaerythritol is limited to be connected with the thermal rearrangement temperature of the polysiloxane modified epoxy resin (4) under heated state, so as to ensure that within the temperature range of 400 degrees Celsius, the carbonized skeleton generated by the dehydration of pentaerythritol is coated by the siloxane network formed by thermal rearrangement, forming a microscopic interpenetrating network structure.

4. The marine weather-resistant and fire-retardant coating based on polysiloxane modification according to claim 1, characterized in that, The surface of the nano-sized titanium dioxide (7) is treated with aluminum and silicon inorganic coating to suppress its photocatalytic activity under ultraviolet irradiation. The nano-sized titanium dioxide (7) is uniformly distributed in the micropores of the marine weather-resistant fireproof coating layer (3) to scatter and absorb ultraviolet radiation and enhance the physical strength of the carbonized layer. The aspect ratio of the aluminum silicate fiber (6) is 20:1 to 50:1 and the fiber diameter is 2 micrometers to 5 micrometers. Under heated conditions, the aluminum silicate fiber (6) is arranged in a random three-dimensional network inside the expanded carbonized layer to form a skeleton support structure that can resist the scouring of hot airflow. The particle size distribution of the microencapsulated ammonium polyphosphate (5), nano-sized titanium dioxide (7) and aluminum silicate fiber (6) in the A component shows a bimodal distribution pattern, in which large-sized functional particles form a filling skeleton and small-sized nanoparticles fill the gaps in the skeleton to construct a tightly packed structure that extends the penetration path of corrosive media.

5. The marine weather-resistant and fire-retardant coating based on polysiloxane modification according to claim 1, characterized in that, The polyamide curing agent in component B is a dimer acid-modified low molecular weight polyamide, which crosslinks with the polysiloxane-modified epoxy resin (4) to form a hydrophobic network with damping properties to absorb structural noise and vibration energy generated by ship operation; the organic modified bentonite anti-settling agent in component A constructs a thixotropic network in the coating system to suspend high-density functional particles. The polyether-modified organosiloxane leveling agent is used to form a silicon-rich layer in a directional arrangement on the surface of the paint film to provide initial hydrophobicity and water stain resistance; after the B component is mixed with the A component, the applicable period at 25 degrees Celsius is not less than 4 hours, and the pencil hardness of the cured marine weather-resistant fireproof coating layer (3) is 2H to 3H, and the volatile organic compound (VOC) content is less than 250g / L.

6. The preparation method of a marine weather-resistant and fire-retardant coating based on polysiloxane modification according to claim 1, characterized in that, Includes the following steps: Step 1, Base Material Premixing: The solvent and the polysiloxane-modified epoxy resin (4) are added to a high-speed disperser and stirred for 20 minutes at a speed of 800 rpm to 1000 rpm to obtain a uniform base material solution; Step 2, High Shear Dispersion: The microencapsulated ammonium polyphosphate (5), the pentaerythritol, the melamine, and the nano-sized titanium dioxide (7) are added sequentially to the base material solution; For the aluminosilicate fiber (6), it is first premixed with a portion of the base material into a paste before being loaded into the solution. Then, the speed of the disperser is increased to 2500 rpm to 3000 rpm for high shear dispersion for 30 minutes to retain the aspect ratio of the aluminum silicate fiber (6); Step 3, additive preparation: add the anti-settling agent, defoamer and leveling agent, reduce the speed to 500 rpm and continue stirring for 15 minutes; Step 4, fine grinding: grind the mixed slurry through a horizontal sand mill, and use an online particle size monitoring system to control the grinding fineness to be less than or equal to 40 micrometers to obtain the A component; All of the above production processes must be carried out under controlled conditions with an ambient humidity of less than 75%, and the finished products are sealed in metal drums and filled with dry nitrogen for top protection.

7. The engineering application system of a marine weather-resistant and fire-retardant coating based on polysiloxane modification according to claim 1, characterized in that, The weather-resistant and fire-retardant coating for ships is applied to the surface of a steel substrate (1) that has been sandblasted to Sa2.5 grade, and an epoxy zinc-rich primer (2) is provided between the steel substrate (1) and the weather-resistant and fire-retardant coating layer (3); the weather-resistant and fire-retardant coating layer (3) exhibits a stepped thermal response mechanism under heating conditions: in the 100-200 degree Celsius range, the light components are steadily released; in the 200-300 degree Celsius range, the wall material of the microencapsulated ammonium polyphosphate (5) ruptures and releases phosphoric acid, inducing the esterification and dehydration of the pentaerythritol; in the 300-500 degree Celsius range, the melamine sublimation drives the expansion of the coating film. Meanwhile, the polysiloxane-modified epoxy resin (4) undergoes thermal rearrangement to form an initial inorganic skeleton, achieving controlled expansion of 20 to 40 times; in the range above 500 degrees Celsius, the silicon phosphate ceramic phase generated by in-situ chemical reaction and the aluminum silicate fiber (6) are synergistically cured to expand the structure, so that the thermal conductivity of the carbonized layer at 1000 degrees Celsius is maintained between 0.05 W / (m·K) and 0.08 W / (m·K); the cured weather-resistant fireproof coating layer (3) has a tensile strength of not less than 5 MPa at room temperature, an elongation at break of not less than 15%, and a char residue of not less than 45% at 800 degrees Celsius.

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