A composite coating for key equipment of basalt fiber reinforced resin and a preparation method thereof

Abstract

The application relates to the technical field of composite coating for key equipment, in particular to a basalt fiber reinforced resin composite coating for key equipment and a preparation method thereof. The basalt fiber reinforced resin composite coating for key equipment comprises a primer layer and a topcoat layer. The primer layer comprises a functional group polyether modified epoxy polyurethane resin double-end epoxy group and a side chain polyether dihydric alcohol modified epoxy polyurethane resin. The topcoat layer comprises a compound of fluorine modified hydroxyl acrylic resin and silicone modified epoxy resin mixed at a mass ratio of 3-5:1-1.5. The film-forming resin of the primer layer is determined, a stable chemical bond is formed between the end epoxy group and the resin matrix in the substrate, basic combination of the coating and the substrate is realized, the design of the coupling agent compound is aimed at the two-phase interface characteristics of the basalt fiber reinforced substrate, and the combination anchoring of the inorganic basalt fiber and the organic resin matrix can be realized.

Description

Technical Field

[0001] This invention relates to the field of composite coating technology for critical equipment, and in particular to a composite coating for critical equipment made of basalt fiber reinforced resin and its preparation method. Background Technology

[0002] The rapid development of the new energy vehicle industry has placed increasingly stringent demands on the comprehensive performance and safety protection of power batteries. As the core protective structure of power batteries, the battery casing not only needs to support the battery cells and related components but also requires excellent mechanical strength, lightweight characteristics, and environmental tolerance. Basalt fiber reinforced resin composites, with their advantages of high strength, high modulus, corrosion resistance, and good insulation, are gradually becoming the preferred substrate for power battery casings. Meanwhile, carbon fiber reinforced composites, with their superior specific strength, specific modulus, and lightweight effect, are also highly representative lightweight materials for new energy vehicle battery casings, and the application scale of both continues to expand in the new energy field. These composite materials combine the rigidity of inorganic fibers with the toughness of organic resins, but their surface has a two-phase interface between inorganic fibers and organic resins, resulting in structural characteristics that are fundamentally different from traditional metal substrates and pure resin substrates, posing entirely new requirements for the compatibility of surface protective coatings.

[0003] Current protective coating technologies for power battery casings are mostly developed around metal or pure resin substrates, leaving a significant technological gap for dedicated coating systems for basalt fiber reinforced resin composites. Ordinary coatings struggle to adapt to the two-phase interface characteristics of composite materials, failing to simultaneously achieve effective bonding between inorganic fibers and organic resins. Under harsh conditions such as high and low temperature cycling and electrolyte immersion during power battery service, they are prone to problems like decreased adhesion, blistering, peeling, and cracking failure. Furthermore, existing coatings cannot simultaneously meet the multiple performance requirements of power battery casings, including high insulation, electrolyte resistance, flame retardancy, heat insulation, weather resistance, and wear resistance. Achieving flame retardancy often comes at the cost of coating density and adhesion, and most only provide passive flame retardancy, failing to provide an effective thermal protection barrier in the early stages of cell malfunctions, thus failing to meet the safety protection requirements of power batteries. Summary of the Invention

[0004] To overcome the aforementioned deficiencies, this application provides a composite coating for key equipment made of basalt fiber reinforced resin and its preparation method.

[0005] In a first aspect, this application provides a composite coating for key equipment made of basalt fiber reinforced resin, employing the following technical solution:

[0006] A composite coating for key equipment made of basalt fiber reinforced resin includes a primer layer, the primer layer comprising the following components in parts by weight: 45-55 parts of bifunctional polyether-modified epoxy polyurethane resin; Two to four doses of the conjugate agent; 12-18 parts of primer hardener; 10-20 parts of functional additives; The bifunctional polyether-modified epoxy polyurethane resin is an epoxy polyurethane resin modified with dual-terminal epoxy groups and side-chain polyether diols.

[0007] Through the above technical solutions, this application clarifies the core composition of the primer layer and the core structural characteristics of the film-forming resin. The core film-forming substance of the primer layer is an epoxy polyurethane resin with epoxy groups at both ends and side chains modified with polyether diol. From the perspective of film formation principle, this molecular structure design allows for stable chemical bonding between the terminal epoxy groups and the resin matrix in the substrate, achieving a basic bond between the coating and the substrate. The polyether polyurethane segments of the side chains can effectively match the thermal expansion characteristics of the substrate, reducing internal stress during coating film formation and service, and avoiding coating cracking and delamination caused by changes in high and low temperature environments. The composite crosslinking agent is designed to target the two-phase interface characteristics of the basalt fiber reinforced substrate, simultaneously achieving bonding and anchoring of inorganic basalt fibers and organic resin matrix, fundamentally solving the core pain point of insufficient interfacial bonding force of ordinary coatings on this substrate. The curing agent and functional additives respectively ensure the formation of the coating crosslinking network and the stability of the film formed during application, laying the core foundation for the protective performance of the entire composite coating system.

[0008] It should be noted that the key equipment targeted in this application includes, but is not limited to, at least one of the following: new energy vehicle battery casings, weaponry, and national defense engineering.

[0009] Furthermore, the key equipment composite coating of the basalt fiber reinforced resin also includes a topcoat layer, which comprises the following components by weight: 40-55 parts of hybrid film-forming substrate; 15-20 parts flame retardant; 5-8 parts of insulating reinforcing filler; 15-20 parts of topcoat hardener; 10-20 parts of functional additives; The hybrid film-forming substrate is a compound of fluorinated modified hydroxyl acrylic resin and organosilicon modified epoxy resin mixed in a mass ratio of (3-5):(1-1.5).

[0010] Through the above technical solution, this application improves the functional design of the entire composite coating system, achieving comprehensive coverage of substrate protection performance. The core of the topcoat layer is the hybrid film-forming matrix formed by compounding. It uses two resins with different properties for compounding design. Utilizing the surface energy differences of different resin segments, a gradient distribution microstructure can be spontaneously formed during the coating film formation process. Among them, the fluorine-modified hydroxyl acrylic resin segments migrate to the surface of the coating in contact with air, forming a protective barrier with excellent weather resistance and chemical resistance, resisting the corrosion of the external environment and electrolyte. The organosilicon-modified epoxy resin segments migrate to the interface between the coating and the primer, forming cross-layer chemical bonds with the active groups in the primer layer, effectively strengthening the interlayer adhesion between the primer and the topcoat, and avoiding the problem of interlayer delamination. The introduction of flame retardants and insulating reinforcing fillers can respectively endow the topcoat layer with excellent flame retardant and heat insulation properties and electrical insulation properties, adapting to the safety protection requirements of power battery shells. Curing agents and functional additives ensure the density of the cross-linked network of the topcoat layer and the film quality, realizing the synergistic effect of multiple protective functions of the composite coating.

[0011] Furthermore, the primer layer also includes 3-5 parts by weight of a compatibility toughening agent and 8-12 parts by weight of an environmentally friendly rust-preventing filler; the interface compatibility toughening agent is a core-shell structured acrylic rubber, and the environmentally friendly rust-preventing filler is a compound of zinc phosphate and aluminum tripolyphosphate.

[0012] Through the above technical solution, this application further optimizes the performance of the primer layer by supplementing the composition of a compatibility toughening agent and an environmentally friendly rust-inhibiting filler. From the two dimensions of film-forming microstructure and long-term protective performance, the interfacial anchoring and protective functions of the primer layer are strengthened. The compatibility toughening agent uses a core-shell structured acrylic rubber. This special core-shell structure can be uniformly dispersed in the resin matrix during the primer film-forming process. It can form good compatibility with the primer film-forming resin, avoiding film-forming defects caused by phase separation. It can also effectively absorb internal stress in the coating through the elastic deformation of the rubber phase, while filling the microscopic gaps formed on the substrate surface due to exposed fibers, preventing cracking and interfacial peeling during service. The environmentally friendly rust-inhibiting filler uses a compounded environmentally friendly rust-inhibiting material, which can form a stable passivation protective layer on the substrate surface, blocking the penetration path of corrosive media, effectively improving the coating's resistance to damp heat and corrosion, while not damaging the coating's electrical insulation properties, further enhancing the long-term service stability and environmental tolerance of the composite coating.

[0013] Furthermore, the functional additive comprises the following substances in parts by weight: Rheology modifier 0.3~0.8 parts; Defoamer 0.2~0.5 parts; Leveling agent 0.2~0.5 parts; 10-15 parts diluent.

[0014] Through the above technical solutions, this application clearly defines the composition of functional additives in the topcoat layer, ensuring the stable realization of various functions of the topcoat layer from two dimensions: coating application compatibility and film-forming quality. Rheology modifiers effectively adjust the rheological properties of the coating system, preventing functional fillers from settling during coating storage and application, ensuring the uniformity of the coating system composition, and adapting to the viscosity requirements of spray application, avoiding defects such as sagging during application. Defoamers effectively eliminate air bubbles introduced during mixing and spray application, preventing pinholes and pores after film formation, ensuring coating density, and blocking the penetration path of corrosive media such as electrolytes. Leveling agents improve the wetting and spreading properties of the coating on the primer layer surface, preventing film-forming defects such as craters and orange peel, ensuring a uniform and smooth coating surface, and promoting the gradient migration of resin segments during film formation, ensuring the stable formation of gradient functional structures. Thinners are used to adjust the application viscosity of the coating, adapting to industrialized spray application processes, ensuring the industrial feasibility of the invention.

[0015] Furthermore, the bifunctional polyether-modified epoxy polyurethane resin is prepared using the following technical solution: Take polyether diol and epoxy resin. Add IPDI dropwise to the polyether diol at a uniform rate of 1.9~2.1:1 NCO / OH molar ratio, adjusting the dropwise addition time to control it at 1~1.5h. During the dropwise addition, maintain the system temperature not exceeding 70℃. After the dropwise addition is complete, add the catalyst, raise the temperature to 70~75℃, and keep the reaction at this temperature for 2.5~3h. The NCO content of the system is detected by di-n-butylamine titration every 30min. When the NCO content reaches the theoretical value, stop the reaction and cool down to below 40℃ to obtain the NCO-terminated polyurethane prepolymer. Nitrogen gas is continuously introduced into the prepolymer, the stirring speed is adjusted to 400~500 rpm, the temperature is raised to 72~75℃, and the dehydrated epoxy resin-solvent mixture is added dropwise at a uniform rate, with the addition time controlled at 2~2.5h. After the addition is complete, add the catalyst, heat to 78~80℃, and keep the reaction at this temperature for 3~4 hours. Check the NCO content of the system every 30 minutes. When the NCO content is ≤0.1%, immediately circulate cooling water to cool down to below 30℃ and terminate the reaction. Add the remaining anhydrous mixed solvent, adjust the solid content of the system to 70±2%, stir at 300rpm for 20 minutes to homogenize, and filter the material through a 200-mesh filter to obtain the target bifunctional polyether modified epoxy polyurethane resin.

[0016] Through the above technical solution, this application clearly defines the preparation method of the core film-forming resin of the primer layer, ensuring the stable realization of the core function of the resin and the reproducibility of the technical solution from the source of molecular structure design. This preparation method precisely constructs the bifunctional molecular structure of the resin through a step-by-step directional reaction design. First, a polyurethane prepolymer with isocyanate terminal groups is synthesized through the reaction of polyether diol and isocyanate. Flexible polyether segments are controllably introduced into the resin system, precisely controlling the resin's flexibility and thermal expansion characteristics, thus achieving good compatibility with basalt fiber reinforced substrates. Then, through a directional grafting reaction, the isocyanate groups of the prepolymer undergo a directional addition reaction with the hydroxyl groups on the epoxy resin backbone. While completely retaining the epoxy terminal groups of the epoxy resin, the flexible polyurethane segments are stably grafted onto the epoxy resin backbone, avoiding the defect of large-scale consumption of epoxy groups in traditional modification processes. This precisely realizes the bifunctional molecular structure design, ensuring the resin's interfacial chemical bonding ability and internal stress regulation ability at the molecular level.

[0017] Furthermore, the insulating reinforcing filler is a mixture of nano-silica and sheet-like nano-boron nitride in a mass ratio of 1:3-5.

[0018] Through the above technical solution, this application clearly defines the composition of the insulating reinforcing filler in the coating layer, achieving a synergistic improvement in electrical insulation performance and mechanical protection performance from the microstructure design level of the coating. The insulating reinforcing filler adopts a compound design of flake-shaped nano-boron nitride and nano-silica. During the coating film formation process, the flake-shaped boron nitride filler forms a labyrinthine structure with stacked layers inside the resin matrix. This structure can significantly improve the volume resistivity and breakdown strength of the coating, fully meeting the high insulation protection requirements of the power battery shell. It can also effectively block the penetration path of corrosive media such as electrolytes through the stacked barrier structure, significantly improving the coating's resistance to media protection. The nano-silica filler can be uniformly dispersed in the resin matrix, effectively improving the crosslinking density and surface hardness of the coating, enhancing the coating's wear resistance and scratch resistance. At the same time, it can form a good synergistic effect with the flake-shaped boron nitride filler, avoiding the defect of increased coating brittleness caused by the addition of a single filler, thus achieving synergistic optimization of the coating's insulation performance, resistance to media, and mechanical properties.

[0019] Secondly, this application provides a method for preparing a composite coating for key equipment made of basalt fiber reinforced resin, employing the following technical solution: A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin includes the following preparation steps: After washing and drying the surface of the basalt fiber reinforced resin battery casing, micro-etching treatment is performed and a coupling agent is coated. After the primer components are mixed evenly, they are cured and sprayed onto the surface of the pretreated basalt fiber reinforced resin battery shell. The primer layer is then dried to complete the preparation. The preparation of the composite coating for key equipment made of basalt fiber reinforced resin is completed by spraying the cured topcoat components onto the surface of the primer layer, followed by leveling and curing.

[0020] Through the above technical solution, this application designs a dedicated substrate pretreatment process for the interfacial characteristics of basalt fiber reinforced resin substrates. First, oil and impurities on the substrate surface are removed through washing and drying. Then, a gentle micro-etching process forms a uniform micro-anchoring structure on the substrate surface without damaging the basalt fibers. The subsequent application of a coupling agent forms an interfacial transition layer on the substrate surface, further strengthening the interfacial adhesion between the primer layer and the substrate. The primer layer is applied using a mixed-curing and then sprayed method to ensure uniform mixing and pre-reaction of the coating components. Precise control of the curing degree during the drying process provides a good foundation for the interlayer bonding of the topcoat layer. The spraying and curing process of the topcoat layer ensures the stable formation of the gradient functional structure during film formation.

[0021] Furthermore, the micro-etching process involves spraying with a 1-2 wt% sodium hydroxide / ethanol solution for 30-60 seconds.

[0022] Through the above technical solution, this application clearly defines the micro-etching process in the substrate pretreatment. Targeting the interfacial characteristics of basalt fiber reinforced resin substrates, it optimizes the core steps of the pretreatment, ensuring stable interfacial adhesion between the coating and the substrate from the source. Traditional substrate pretreatment processes often employ deep etching with strong acids and alkalis or high-pressure sandblasting. For basalt fiber reinforced substrates, these processes easily cause basalt fibers on the substrate surface to detach and break, forming numerous interfacial defects, which significantly reduces the adhesion between the coating and the substrate. The micro-etching process defined in this claim uses a mild alkaline alcohol solution for spraying, only performing moderate micro-etching on the resin matrix on the substrate surface to form a uniform micro-rough structure. This provides stable mechanical anchoring sites for the primer layer, while avoiding corrosion and damage to the inorganic basalt fibers. It completely preserves the structural integrity of the substrate surface, avoiding interfacial weakness caused by fiber detachment, and fundamentally ensuring the long-term interfacial adhesion stability between the coating and the substrate.

[0023] Furthermore, the dry film thickness of the primer layer is 30~50μm, and the dry film thickness of the topcoat layer is 50~70μm.

[0024] Through the above technical solutions, this application clearly defines the dry film thickness of the primer and topcoat layers. From the perspective of the overall structural design of the composite coating, it achieves a balance between protective performance and construction economy, ensuring the stable performance of various functions of the composite coating. The primer layer, as the interface anchoring layer connecting the substrate and the topcoat, must be designed to ensure its thickness fully covers the microscopic unevenness of the substrate surface, fills the microscopic gaps formed by exposed fibers, and forms a continuous and uniform interface anchoring layer. It must also avoid problems such as increased internal stress and cracking during curing due to excessive thickness. The topcoat layer, as the core functional layer of the composite coating, must be designed to ensure the formation of a stable gradient functional structure, achieving comprehensive protection of flame retardancy, insulation, weather resistance, and media resistance. It must also avoid defects such as increased construction costs and incomplete curing due to excessive thickness. The matching thickness design of the two coating layers also ensures the curing synergy of the primer and topcoat layers, promotes the formation of interlayer chemical bonding interpenetrating networks, avoids interlayer delamination, and is fully adaptable to industrial construction application scenarios.

[0025] In summary, this application has the following beneficial effects: First, this application, starting from molecular structure design and interface characteristic adaptation, completely solves the industry pain point of insufficient interfacial adhesion of existing coatings on basalt fiber reinforced resin substrates. The solution addresses the two-phase interfacial characteristics of the coexistence of inorganic fibers and organic resin in the substrate by designing a film-forming resin with a bifunctional structure and a compounded interfacial anchoring system. This system can simultaneously achieve stable chemical bonding with the organic resin matrix of the substrate and directional anchoring of the inorganic basalt fibers, fundamentally eliminating weak points in interfacial adhesion. The accompanying mild substrate pretreatment process can construct uniform micro-anchoring sites without damaging the fiber structure, further enhancing the interfacial adhesion between the coating and the substrate. This design ensures that the coating maintains a stable interfacial adhesion state in the harsh service environment of power batteries, effectively avoiding coating failure problems such as blistering, peeling, and cracking under high and low temperature cycling and electrolyte erosion conditions, laying a solid foundation for the realization of subsequent protective functions.

[0026] Secondly, this technical solution overcomes the technical bottleneck of existing coatings' inability to simultaneously provide multiple protective properties through a gradient functionalized coating structure design, achieving synergistic optimization of the protective performance required for power battery casings. Utilizing the surface energy differences of different film-forming resins, the solution spontaneously forms a gradient functional structure during film formation in a single application. The surface layer constructs a dense protective barrier resistant to weathering and chemical corrosion, the inner layer achieves strong interfacial bonding with the primer layer, and the middle layer provides core protective functions such as flame retardancy and insulation. The accompanying functional filler system forms a good synergistic effect with the film-forming substrate, simultaneously improving the coating's electrical insulation performance, resistance to media penetration, and mechanical protection performance without compromising its density and adhesion. This avoids the shortcomings of traditional coating functional modification where some aspects are sacrificed for others, achieving comprehensive protection without the need for multi-layer, step-by-step application, significantly improving the coating's overall protective capability and industrial adaptability.

[0027] Third, this technical solution addresses the safety protection needs throughout the entire lifecycle of power batteries, achieving an organic combination of passive and active safety protection, significantly improving the safety redundancy and long-term service stability of the battery casing. The flame retardant designed in this solution can rapidly form a dense and stable heat-insulating carbon layer in the early stages of abnormal cell heating. This not only meets stringent flame retardant requirements but also effectively isolates heat transfer, slowing the spread of thermal runaway and providing an additional active barrier for the safety of the power battery. Simultaneously, the coating system, through directional molecular structure design, achieves precise matching with the thermal expansion characteristics of the substrate. This effectively releases internal stress during coating formation and service, preventing performance degradation during long-term high and low temperature cycling, ensuring stable protective performance throughout the entire service life, effectively extending the service life of the power battery casing, and meeting the long-term, stringent service requirements of new energy power batteries. Detailed Implementation

[0028] The present application will be further described in detail below with reference to the embodiments.

[0029] The raw materials and instruments used in this embodiment are shown below, but are not limited thereto. Unless otherwise specified, the raw materials used are of analytical grade.

[0030] Preparation Example 1 Bifunctional polyether modified epoxy polyurethane resin 100.0g of polyether diol was dehydrated, and dry nitrogen gas was continuously introduced into the dehydrated polyether diol. The stirring speed was kept stable at 350 rpm, the temperature was raised to 60℃, and 44.5g of IPDI was added dropwise at a uniform rate. The addition time was strictly controlled at 75 min. During the addition, the system temperature was maintained at 65℃ by water bath temperature control. After the addition was completed, 0.04g of DBTDL catalyst was added, the temperature was raised to 72℃, and the reaction was kept at this temperature for 2 h 45 min. The NCO content of the system was detected by di-n-butylamine-hydrochloric acid titration every 30 min. When the NCO content reached the theoretical value of 3.9% and the fluctuation was ≤0.1% in two consecutive tests, the reaction was stopped immediately, and the temperature was lowered to 38℃ by cooling water to obtain the NCO-terminated polyurethane prepolymer.

[0031] Dry nitrogen gas was continuously introduced into the prepolymer, the stirring speed was adjusted to 450 rpm, and the temperature was raised to 73°C. 152.0 g of dehydrated E-44 epoxy resin and 60.0 g of anhydrous mixed solvent (a 1:1 mass ratio of propylene glycol methyl ether acetate and isomeric xylene) were added dropwise at a uniform rate over 135 min, maintaining the system temperature at 74°C during the addition. After the addition was complete, 0.02 g of DBTDL catalyst was added, the temperature was raised to 79°C, and the reaction was maintained for 210 min. The NCO content of the system was monitored every 30 min. When the NCO content was ≤0.1%, cooling water was immediately introduced to rapidly cool the system to 28°C, terminating the reaction. The remaining 67.0 g of anhydrous mixed solvent was added to the reaction system to adjust the solid content to 70%, and homogenization was completed by stirring at 300 rpm for 20 min. The mixture was then filtered through a 200-mesh filter to obtain the target bifunctional polyether-modified epoxy polyurethane resin.

[0032] Preparation Example 2 Hybrid film-forming substrate 1 266.67g of KN8176F fluorinated hydroxyl acrylic resin and 71.43g of EPSI-3866 silicone-modified epoxy resin were preheated in a 40℃ constant temperature water bath for 30min to reduce the viscosity of the system and ensure uniformity in subsequent mixing. The preheated KN8176F and EPSI-3866 were added to a 500mL four-necked flask equipped with nitrogen protection, a temperature control jacket, and a variable frequency stirrer. Dry nitrogen was purged throughout the process, and the mixture was stirred at 550rpm for 25min at room temperature to obtain a preliminary homogeneous mixture. The resin mixing system was prepared; the temperature control system was turned on and the system was heated to 61℃, the stirring speed was reduced to 400rpm, 0.15g of DBTDL catalyst was added, and the reaction was kept at the temperature for 1.2h; after the temperature was kept at the temperature, cooling water was immediately circulated to cool the system to 27℃ to terminate the pre-reaction; 51.90g of mixed diluent was added to adjust the solid content of the system to 55±1%, and the mixture was stirred at 300rpm for 15min to homogenize it. The mixture was then filtered through a 200-mesh filter, sealed and stored in the dark to prepare the hybrid film-forming matrix 1.

[0033] Preparation Example 3 Hybrid film-forming substrate 2 333.33g of KN8176F fluorinated hydroxyl acrylic resin and 85.71g of EPSI-3866 silicone-modified epoxy resin were preheated in a 40℃ constant temperature water bath for 30min to reduce the viscosity of the system and ensure uniformity of subsequent mixing. In a 500mL four-necked flask equipped with nitrogen protection, a temperature control jacket, and a variable frequency stirrer, the preheated KN8176F and EPSI-3866 were added, and dry nitrogen was purged throughout the process. The mixture was stirred at 600rpm for 25min at room temperature to obtain the desired product. A preliminary homogeneous resin mixture was prepared. The temperature control system was turned on, and the system was heated to 63°C. The stirring speed was reduced to 500 rpm, and 0.23 g of DBTDL catalyst was added. The reaction was kept at this temperature for 1.4 h. After the reaction was completed, cooling water was immediately introduced to cool the system down to 29°C to terminate the pre-reaction. 60.96 g of mixed diluent was added to adjust the solid content of the system to 55 ± 1%. The mixture was stirred at 300 rpm for 15 min to homogenize it. The mixture was then filtered through a 200-mesh filter, sealed, and stored in the dark to prepare the hybrid film-forming matrix 2.

[0034] Preparation Example 4 Hybrid film-forming substrate 3 250.00g of KN8176F fluorinated hydroxyl acrylic resin and 71.43g of EPSI-3866 silicone-modified epoxy resin were preheated in a 40℃ constant temperature water bath for 30min to reduce the viscosity of the system and ensure uniformity of subsequent mixing. In a 500mL four-necked flask equipped with nitrogen protection, a temperature control jacket, and a variable frequency stirrer, the preheated KN8176F and EPSI-3866 were added, and dry nitrogen was purged throughout the process. The mixture was stirred at 550rpm for 25min at room temperature to obtain the desired product. A preliminary homogeneous resin mixture was prepared. The temperature control system was turned on, and the system was heated to 62°C. The stirring speed was reduced to 450 rpm, and 0.16 g of DBTDL catalyst was added. The reaction was kept at this temperature for 1.5 h. After the reaction was completed, cooling water was immediately introduced to cool the system down to 28°C to terminate the pre-reaction. 48.57 g of mixed diluent was added to adjust the solid content of the system to 55 ± 1%. The mixture was stirred at 300 rpm for 15 min to homogenize it. The mixture was then filtered through a 200-mesh filter, sealed, and stored in the dark to prepare the hybrid film-forming matrix 3.

[0035] Preparation Example 5 Take 0.3 kg of fumed silica, 0.2 kg of BYK-052 defoamer, 0.2 kg of BYK-340 leveling agent and 10 kg of propylene glycol methyl ether acetate diluent, stir and mix to prepare functional additive 1.

[0036] Preparation Example 6 Take 0.5 kg of fumed silica, 0.3 kg of BYK-052 defoamer, 0.3 kg of BYK-340 leveling agent and 12 kg of propylene glycol methyl ether acetate diluent, stir and mix to prepare functional additive 2.

[0037] Preparation Example 7 Take 0.8 kg of fumed silica, 0.5 kg of BYK-052 defoamer, 0.5 kg of BYK-340 leveling agent and 15 kg of propylene glycol methyl ether acetate diluent, stir and mix to prepare functional additive 3.

[0038] Preparation Example 8 primer layer hardener Take 7.2 kg of hexamethylene diisocyanate, 1 kg of modified alicyclic amine epoxy curing agent D-230, 0.3 kg of epoxy silane coupling agent KH560, 0.35 kg of propylene glycol methyl ether acetate, and 0.35 kg of isomerized xylene, stir and mix them to prepare the primer curing agent.

[0039] Preparation Example 9 Zinc phosphate and aluminum tripolyphosphate were mixed in a 1:1 mass ratio to prepare an environmentally friendly rust-preventive filler.

[0040] Preparation Example 10 Insulation Reinforcing Filler 1 Nano-silica and sheet-like nano-boron nitride were mixed at a mass ratio of 1:3 to prepare insulating reinforcing filler 1.

[0041] Preparation Example 11 Insulation reinforcement filler 2 Nano-silica and sheet-like nano-boron nitride were mixed at a mass ratio of 1:4 to prepare insulating reinforcing filler 2.

[0042] Preparation Example 12 Insulation Reinforcing Filler 3 Nano-silica and sheet-like nano-boron nitride were mixed at a mass ratio of 1:5 to prepare insulating reinforcing filler 3.

[0043] Example 1 A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin includes the following preparation steps: A composite coating for key equipment made of basalt fiber reinforced resin comprises the following substances by weight: 45kg of bifunctional polyether-modified epoxy polyurethane resin, 1kg of coupling agent KH551, 1kg of coupling agent NDZ-105, 12kg of primer curing agent and 10kg of functional additive 1; After washing and drying the surface of the basalt fiber reinforced resin battery shell, it was sprayed with a 1 wt% sodium hydroxide / ethanol solution for 30 seconds and coated with a 1% aminosilane coupling agent ethanol solution. The wet film thickness was 5 μm, and it was air-dried at room temperature for 10 minutes. After the primer components are mixed evenly, they are cured and sprayed onto the surface of the pretreated basalt fiber reinforced resin battery shell. The primer spraying viscosity is 20s, the wet film thickness is 40μm, and after surface drying at room temperature for 30min, it is baked at 60℃ until dry, thus completing the preparation of the composite coating for key equipment made of basalt fiber reinforced resin.

[0044] Example 2 A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin includes the following preparation steps: A composite coating for key equipment made of basalt fiber reinforced resin comprises the following substances by weight: 50kg of bifunctional polyether-modified epoxy polyurethane resin, 1kg of coupling agent KH551, 1kg of coupling agent NDZ-105, 15kg of primer curing agent and 15kg of functional additives 2; After washing and drying the surface of the basalt fiber reinforced resin battery shell, it was sprayed with a 1 wt% sodium hydroxide / ethanol solution for 45 seconds and coated with a 1% aminosilane coupling agent ethanol solution. The wet film thickness was 8 μm, and it was air-dried at room temperature for 10 minutes. After the primer components are mixed evenly, they are cured and sprayed onto the surface of the pretreated basalt fiber reinforced resin battery shell. The primer spraying viscosity is 20s, the wet film thickness is 50μm, and after drying at room temperature for 30min, it is baked at 60℃ until dry, thus completing the preparation of the composite coating for key equipment made of basalt fiber reinforced resin.

[0045] Example 3 A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin includes the following preparation steps: A composite coating for key equipment made of basalt fiber reinforced resin comprises the following substances by weight: 55 kg of bifunctional polyether modified epoxy polyurethane resin, 2 kg of coupling agent KH551, 2 kg of coupling agent NDZ-105, 18 kg of primer curing agent and 20 kg of functional additives 3; After washing and drying the surface of the basalt fiber reinforced resin battery shell, it was sprayed with a 2wt% sodium hydroxide / ethanol solution for 60s and coated with a 1% aminosilane coupling agent ethanol solution. The wet film thickness was 10μm, and it was air-dried at room temperature for 10min. After the primer components are mixed evenly, they are cured and sprayed onto the surface of the pretreated basalt fiber reinforced resin battery shell. The primer spraying viscosity is 20s, the wet film thickness is 60μm, and after surface drying at room temperature for 30min, it is baked at 60℃ until dry, thus completing the preparation of the composite coating for key equipment made of basalt fiber reinforced resin.

[0046] Example 4 A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin includes the following preparation steps: A composite coating for key equipment made of basalt fiber reinforced resin comprises the following substances by weight: 55kg of bifunctional polyether-modified epoxy polyurethane resin, 8kg of environmentally friendly rust-preventive filler, 3kg of core-shell structure acrylate rubber ACRKM-355P, 2kg of coupling agent KH551, 2kg of coupling agent NDZ-105, 18kg of primer curing agent and 20kg of functional additives. After washing and drying the surface of the basalt fiber reinforced resin battery cover, it was sprayed with a 2wt% sodium hydroxide / ethanol solution for 60s and coated with a 1% aminosilane coupling agent ethanol solution. The wet film thickness was 10μm, and it was air-dried at room temperature for 10min. After the primer components are mixed evenly, they are cured and sprayed onto the surface of the pretreated basalt fiber reinforced resin battery cover plate. The primer spraying viscosity is 20s, the wet film thickness is 60μm, and after surface drying at room temperature for 30min, it is baked at 60℃ until dry, thus completing the preparation of the composite coating for key equipment made of basalt fiber reinforced resin.

[0047] Example 5 A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin includes the following preparation steps: A composite coating for key equipment made of basalt fiber reinforced resin comprises the following substances by weight: 55kg of bifunctional polyether modified epoxy polyurethane resin, 10kg of environmentally friendly rust-preventive filler, 4kg of core-shell structure acrylate rubber ACRKM-355P, 2kg of coupling agent KH551, 2kg of coupling agent NDZ-105, 18kg of primer curing agent and 20kg of functional additives. After washing and drying the surface of the basalt fiber reinforced resin automotive leaf spring, it was sprayed with a 2wt% sodium hydroxide / ethanol solution for 60s and coated with a 1% aminosilane coupling agent ethanol solution. The wet film thickness was 10μm, and it was air-dried at room temperature for 10min. After the primer components are mixed evenly, they are cured and sprayed onto the pretreated basalt fiber reinforced resin automotive leaf spring surface. The primer spraying viscosity is 20s, the wet film thickness is 60μm, and after surface drying at room temperature for 30min, it is baked at 60℃ until dry, thus completing the preparation of the composite coating for key equipment made of basalt fiber reinforced resin.

[0048] Example 6 A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin includes the following preparation steps: A composite coating for key equipment made of basalt fiber reinforced resin comprises the following substances by weight: 55kg of bifunctional polyether modified epoxy polyurethane resin, 12kg of environmentally friendly rust-preventive filler, 5kg of core-shell structure acrylate rubber ACRKM-355P, 2kg of coupling agent KH551, 2kg of coupling agent NDZ-105, 18kg of primer curing agent and 20kg of functional additives. After washing and drying the basalt fiber reinforced resin automotive chassis protection plate, it was sprayed with a 2wt% sodium hydroxide / ethanol solution for 60s and coated with a 1% aminosilane coupling agent ethanol solution. The wet film thickness was 10μm, and it was air-dried at room temperature for 10min. After the primer components are mixed evenly, they are cured and sprayed onto the pretreated basalt fiber reinforced resin automotive chassis guard plate surface. The primer spraying viscosity is 20s, the wet film thickness is 60μm, and after surface drying at room temperature for 30min, it is baked at 60℃ until dry, thus completing the preparation of the basalt fiber reinforced resin composite coating for key equipment.

[0049] Example 7 A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin includes the following preparation steps: A composite coating for key equipment made of basalt fiber reinforced resin comprises the following substances by weight: Primer layer: 55kg of bifunctional polyether modified epoxy polyurethane resin, 10kg of environmentally friendly rust-preventive filler, 4kg of core-shell structure acrylate rubber ACRKM-355P, 2kg of coupling agent KH551, 2kg of coupling agent NDZ-105, 18kg of primer layer curing agent and 20kg of functional additives 2. Topcoat layer: 48kg hybrid film-forming matrix 1, 17kg flame retardant ammonium polyphosphate, 7kg insulation reinforcing filler 2, 17kg topcoat curing agent IPDI trimer and 15kg functional additive 1; After washing and drying the surface of the basalt fiber reinforced resin automotive interior reinforcing panel, it was sprayed with a 2wt% sodium hydroxide / ethanol solution for 60s and coated with a 1% aminosilane coupling agent ethanol solution. The wet film thickness was 10μm, and it was air-dried at room temperature for 10min. After the primer components are mixed evenly, they are cured and sprayed onto the surface of the pretreated basalt fiber reinforced resin automotive interior reinforcement panel. The primer spraying viscosity is 20s, the wet film thickness is 60μm, and after being surface dried at room temperature for 30 minutes, it is baked at 60℃ until semi-dry. After the topcoat components are mixed evenly and cured, they are sprayed onto the semi-dry surface of the primer. The topcoat spraying viscosity is 20~24s, the wet film thickness is 60~80μm, and after leveling at room temperature for 15min, it is baked at 80℃ for 30min to fully cure, thus obtaining a composite coating.

[0050] Example 8 A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin includes the following preparation steps: A composite coating for key equipment made of basalt fiber reinforced resin comprises the following substances by weight: Primer layer: 55kg of bifunctional polyether modified epoxy polyurethane resin, 10kg of environmentally friendly rust-preventive filler, 4kg of core-shell structure acrylate rubber ACRKM-355P, 2kg of coupling agent KH551, 2kg of coupling agent NDZ-105, 18kg of primer layer curing agent and 20kg of functional additives 2. Topcoat layer: 40kg hybrid film-forming matrix 1, 15kg flame retardant ammonium polyphosphate, 5kg insulation reinforcing filler 1, 15kg topcoat curing agent IPDI trimer and 10kg functional additives 1; After washing and drying the surface of the basalt fiber reinforced resin battery shell, it was sprayed with a 2wt% sodium hydroxide / ethanol solution for 60s and coated with a 1% aminosilane coupling agent ethanol solution. The wet film thickness was 10μm, and it was air-dried at room temperature for 10min. After the primer components are mixed evenly, they are cured and sprayed onto the surface of the pretreated basalt fiber reinforced resin battery shell. The primer spraying viscosity is 20s, the wet film thickness is 60μm, and after being surface dried at room temperature for 30min, it is baked at 60℃ until it is semi-dry. After the topcoat components are mixed evenly and cured, they are sprayed onto the semi-dry surface of the primer. The topcoat spraying viscosity is 20s, the wet film thickness is 60μm, and after leveling at room temperature for 15min, it is baked at 80℃ for 30min to fully cure, thus obtaining a composite coating.

[0051] Example 9 A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin includes the following preparation steps: A composite coating for key equipment made of basalt fiber reinforced resin comprises the following substances by weight: Primer layer: 55kg of bifunctional polyether modified epoxy polyurethane resin, 10kg of environmentally friendly rust-preventive filler, 4kg of core-shell structure acrylate rubber ACRKM-355P, 2kg of coupling agent KH551, 2kg of coupling agent NDZ-105, 18kg of primer layer curing agent and 20kg of functional additives 2. Topcoat layer: 55kg hybrid film-forming matrix 1, 20kg flame retardant ammonium polyphosphate, 8kg insulation reinforcing filler 3, 20kg topcoat curing agent IPDI trimer and 20kg functional additive 1; After washing and drying the surface of the basalt fiber reinforced resin battery shell, it was sprayed with a 2wt% sodium hydroxide / ethanol solution for 60s and coated with a 1% aminosilane coupling agent ethanol solution. The wet film thickness was 10μm, and it was air-dried at room temperature for 10min. After the primer components are mixed evenly, they are cured and sprayed onto the surface of the pretreated basalt fiber reinforced resin battery shell. The primer spraying viscosity is 20s, the wet film thickness is 60μm, and after being surface dried at room temperature for 30min, it is baked at 60℃ until it is semi-dry. After the topcoat components are mixed evenly and cured, they are sprayed onto the semi-dry surface of the primer. The topcoat spraying viscosity is 24s, the wet film thickness is 80μm, and after leveling at room temperature for 15min, it is baked at 80℃ for 30min to fully cure, thus obtaining a composite coating.

[0052] Performance testing The performance of the composite coatings prepared in Examples 1-9 was tested: Initial adhesion of paint film: tested according to standard GB / T9286-1998; Artificial weathering resistance: tested according to standard GB / T1865-2009; Electrical breakdown strength: tested according to standard GB / T1408.1-2006; Vertical burning flame retardancy rating: tested according to standards GB / T2408-2021 and UL94-2023.

[0053] The specific test results are shown in Table 1 below: Table 1 Performance Test Table

[0054] As can be seen from the table above and Examples 1-9, Examples 1-3 are the basic primer formulations, while Examples 4-6 added core-shell toughening agents and environmentally friendly rust-inhibiting fillers. The test data shows that the adhesion, high and low temperature stability, electrolyte resistance, and weather resistance of the coatings after adding the components have all been significantly improved, verifying the optimizing effect of toughening agents and rust-inhibiting fillers on the performance of the primers. Among them, Example 5 is the intermediate optimal formulation with the best overall performance.

[0055] Examples 7-9 represent complete composite coating systems combining primer and topcoat. Compared to examples containing only primer, the insulation performance is improved by more than one order of magnitude, the flame retardancy rating reaches the V-0 level required for power batteries, and the electrolyte resistance, weather resistance, and high and low temperature stability all achieve a qualitative leap, verifying the key role of gradient functional topcoat in the core protective performance of power battery casing.

[0056] As can be seen from the technical solutions in Examples 7-9, this technical solution, through a gradient functionalized coating structure design, overcomes the technical bottleneck of existing coatings' inability to simultaneously achieve multiple protective properties, realizing the synergistic optimization of the protective performance required for the power battery casing. Utilizing the surface energy differences of different film-forming resins, the solution can spontaneously form a gradient functional structure during film formation in a single application. The surface layer can construct a dense protective barrier resistant to weathering and chemical corrosion, the inner layer can achieve strong interfacial bonding with the primer layer, and the middle layer can bear core protective functions such as flame retardancy and insulation. The matching functional filler system can form a good synergistic effect with the film-forming substrate, simultaneously improving the coating's electrical insulation performance, resistance to media penetration, and mechanical protection performance without compromising the coating's density and adhesion. This avoids the shortcomings of traditional coating functional modification where some aspects are sacrificed for others, achieving comprehensive protection without multi-layer, step-by-step construction, significantly improving the coating's overall protective capability and industrial adaptability.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A composite coating for key equipment made of basalt fiber reinforced resin, characterized in that, Includes a primer layer, said primer layer comprising the following components in parts by weight: 45-55 parts of bifunctional polyether-modified epoxy polyurethane resin; Two to four doses of the conjugate agent; 12-18 parts of primer hardener; 10-20 parts of functional additives; The bifunctional polyether-modified epoxy polyurethane resin is an epoxy polyurethane resin modified with dual-terminal epoxy groups and side-chain polyether diols.

2. The composite coating for key equipment made of basalt fiber reinforced resin according to claim 1, characterized in that, The key equipment composite coating of the basalt fiber reinforced resin also includes a topcoat layer, which comprises the following components by weight: 40-55 parts of hybrid film-forming substrate; 15-20 parts flame retardant; 5-8 parts of insulating reinforcing filler; 15-20 parts of topcoat hardener; 10-20 parts of functional additives; The hybrid film-forming substrate is a compound of fluorinated modified hydroxyl acrylic resin and organosilicon modified epoxy resin mixed in a mass ratio of (3-5):(1-1.5).

3. The composite coating for key equipment made of basalt fiber reinforced resin according to claim 1, characterized in that, The primer layer also includes 3-5 parts by weight of a compatibility toughening agent and 8-12 parts by weight of an environmentally friendly rust-preventing filler; the interface compatibility toughening agent is a core-shell structured acrylic rubber, and the environmentally friendly rust-preventing filler is a compound of zinc phosphate and aluminum tripolyphosphate.

4. The composite coating for key equipment made of basalt fiber reinforced resin according to claim 2, characterized in that, The functional additives comprise the following substances in parts by weight: Rheology modifier 0.3~0.8 parts; Defoamer 0.2~0.5 parts; Leveling agent 0.2~0.5 parts; 10-15 parts diluent.

5. The composite coating for key equipment made of basalt fiber reinforced resin according to claim 1, characterized in that, The bifunctional polyether-modified epoxy polyurethane resin is prepared using the following technical solution: Take polyether diol and epoxy resin. Add IPDI dropwise to the polyether diol at a uniform rate of 1.9~2.1:1 NCO / OH molar ratio, adjusting the dropwise addition time to control it at 1~1.5h. During the dropwise addition, maintain the system temperature not exceeding 70℃. After the dropwise addition is complete, add the catalyst, raise the temperature to 70~75℃, and keep the reaction at this temperature for 2.5~3h. The NCO content of the system is detected by di-n-butylamine titration every 30min. When the NCO content reaches the theoretical value, stop the reaction and cool down to below 40℃ to obtain the NCO-terminated polyurethane prepolymer. Nitrogen gas is continuously introduced into the prepolymer, the stirring speed is adjusted to 400~500 rpm, the temperature is raised to 72~75℃, and the dehydrated epoxy resin-solvent mixture is added dropwise at a uniform rate, with the addition time controlled at 2~2.5h. After the addition is complete, add the catalyst, heat to 78~80℃, and keep the reaction at this temperature for 3~4 hours. Check the NCO content of the system every 30 minutes. When the NCO content is ≤0.1%, immediately circulate cooling water to cool down to below 30℃ and terminate the reaction. Add the remaining anhydrous mixed solvent, adjust the solid content of the system to 70±2%, stir at 300rpm for 20 minutes to homogenize, and filter the material through a 200-mesh filter to obtain the target bifunctional polyether modified epoxy polyurethane resin.

6. The composite coating for key equipment made of basalt fiber reinforced resin according to claim 1, characterized in that, The insulating reinforcing filler is a mixture of nano-silica and sheet-like nano-boron nitride in a mass ratio of 1:3-5.

7. A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin according to any one of claims 1-6, characterized in that, The preparation steps include the following: After washing and drying the surface of the basalt fiber reinforced resin battery casing, micro-etching treatment is performed and a coupling agent is coated. After the primer components are mixed evenly, they are cured and sprayed onto the surface of the pretreated basalt fiber reinforced resin battery shell. The primer layer is then dried to complete the preparation. The preparation of the composite coating for key equipment made of basalt fiber reinforced resin is completed by spraying the cured topcoat components onto the surface of the primer layer, followed by leveling and curing.

8. A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin according to claim 7, characterized in that, The micro-etching process involves spraying with a 1-2 wt% sodium hydroxide / ethanol solution for 30-60 seconds.

9. A method for preparing a composite coating for key equipment made of basalt fiber reinforced resin according to claim 7, characterized in that, The dry film thickness of the primer layer is 30~50μm, and the dry film thickness of the topcoat layer is 50~70μm.

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