Non-asbestos sealing plate and preparation method thereof

Abstract

The invention belongs to the field of sealing materials, and discloses an asbestos-free sealing plate and a preparation method thereof. The composite material is prepared from the following raw materials in parts by weight: 20-30 parts of inorganic composite fibers, 5-10 parts of organic reinforced fibers, 35-45 parts of a modified high-temperature-resistant matrix material, 5-10 parts of nitrile rubber, 8-15 parts of an environment-friendly flame retardant, 1-3 parts of a lubricant, 1-2 parts of a coupling agent, 3-6 parts of organic modified montmorillonite and 1-3 parts of graphene. The invention aims to overcome the defects of insufficient high temperature resistance, poor environmental protection property, poor sealing property, insufficient mechanical strength and short service life of an asbestos-free sealing plate in the prior art, and provides the asbestos-free sealing plate and the preparation method thereof. The sealing plate does not contain asbestos, formaldehyde and heavy metal, has excellent high temperature resistance, mechanical property and sealing property, is stable and controllable in preparation process, and is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of sealing materials, in particular to an asbestos-free sealing plate and a preparation method thereof. Background Art

[0002] As a key functional material in the industrial field, sealing plates are widely used for static sealing in pipe flanges, valve connections, and other areas under high-temperature and high-pressure conditions in chemical reactors, power boilers, and metallurgical equipment. Their core function is to prevent media leakage and ensure the safety and economic efficiency of equipment operation. Therefore, they place stringent requirements on the material's high-temperature resistance, sealing properties, mechanical strength, and environmental friendliness.

[0003] Traditional sealing materials often use asbestos as a core reinforcement component. Asbestos was once widely used due to its excellent heat resistance and mechanical properties. However, with increasing environmental awareness, the strong carcinogenicity of asbestos fibers has been clearly established. Long-term exposure can lead to serious diseases such as asbestosis and lung cancer. Furthermore, asbestos waste is difficult to degrade, causing persistent pollution to soil and water sources.

[0004] Although the research and development of existing asbestos-free sealing panels has made some progress, there are still many technical bottlenecks: First, the high temperature resistance is insufficient. The long-term operating temperature of most products is limited to below 150°C. In high temperature environments above 200°C, problems such as substrate aging and loss of elasticity are prone to occur, leading to sealing failure. Second, environmental performance varies. Some products use adhesives containing formaldehyde or flame retardants containing heavy metals such as lead and cadmium to improve performance, which poses the risk of volatile harmful substances and does not comply with international environmental standards such as RoHS and REACH. Third, it is difficult to balance performance. A single fiber reinforcement system cannot achieve both mechanical strength and sealing. For example, sealing panels reinforced only with glass fiber are brittle and prone to cracking, while products reinforced only with organic fibers lack heat resistance. Fourth, there are defects in the preparation process. The poor compatibility between the fiber and the matrix material leads to weak interfacial bonding, and pores are easily generated inside the material, affecting the sealing reliability. Fifth, in a humid or corrosive medium environment, existing sealing plates are prone to hygroscopic expansion or corrosion degradation, which greatly shortens their service life and increases equipment maintenance costs.

[0005] Currently, the asbestos-free sealing boards on the market are mainly divided into three categories: rubber-based, resin-based and composite-based. Rubber-based sealing boards have good elasticity but poor heat resistance, and the long-term use temperature usually does not exceed 120°C; resin-based sealing boards have improved heat resistance, but are more brittle, and the sealing surface is prone to cracks due to vibration or temperature difference stress; although composite-based sealing boards have tried to combine fibers and matrices, the fiber type selection is single, the matrix modification is insufficient, and there is a lack of effective interface optimization methods, resulting in the comprehensive performance of the material being difficult to meet the needs of high-end industrial scenarios. In addition, some products use benzene solvents or phosphorus-containing flame retardants in the production process, which not only endangers the health of operators, but also causes secondary pollution during waste disposal. Therefore, an asbestos-free sealing board with excellent high temperature resistance, reliable sealing, mechanical strength and comprehensive environmental protection performance is proposed. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of existing asbestos-free sealing panels, such as insufficient high-temperature resistance, poor environmental performance, poor sealing properties, insufficient mechanical strength, and a short service life. The invention provides an asbestos-free sealing panel and a method for preparing the panel. The panel contains no asbestos, formaldehyde, or heavy metals, exhibits excellent high-temperature resistance, mechanical properties, and sealing performance, and features a stable and controllable preparation process, making it suitable for industrial production.

[0007] In order to achieve the above object, the present invention provides the following technical solutions: The technical solution provided by the present invention is: an asbestos-free sealing plate, characterized in that it is made of the following raw materials in parts by weight: 20-30 parts of inorganic composite fiber, 5-10 parts of organic reinforcing fiber, 35-45 parts of modified high-temperature resistant matrix material, 5-10 parts of nitrile rubber, 8-15 parts of environmentally friendly flame retardant, 1-3 parts of lubricant, 1-2 parts of coupling agent, 3-6 parts of organic modified montmorillonite, and 1-3 parts of graphene; The inorganic composite fiber is a mixture of aluminum silicate fiber and basalt fiber, with a weight ratio of (2-3):1; The organic reinforcing fiber is aramid fiber; the modified high-temperature resistant matrix material is an epoxy resin modified with a silane coupling agent, wherein the silane coupling agent is γ-aminopropyltriethoxysilane. The modification process is as follows: the epoxy resin is heated to 80-90°C, γ-aminopropyltriethoxysilane is added dropwise at a rate of 3-5% by weight of the epoxy resin while stirring, and after the addition is completed, the mixture is stirred and kept warm for 1-2 hours, and then cooled to room temperature; The environmentally friendly flame retardant is magnesium hydroxide, with a particle size of 1-5 μm; The organic modified montmorillonite is sodium montmorillonite modified with hexadecyltrimethylammonium bromide, and its interlayer spacing is 2.5-3.5nm; Graphene is in the form of flakes with a thickness of 0.5-2 nm and a flake diameter of 5-10 μm; And the asbestos-free sealing board does not contain formaldehyde, heavy metals and asbestos components.

[0008] Furthermore, the acrylonitrile content of the nitrile rubber is 25-35%, and the Mooney viscosity (ML1+4, 100°C) is 40-60.

[0009] Furthermore, the length of the aluminum silicate fiber is 0.5-2 mm and the diameter is 3-8 μm; the length of the basalt fiber is 1-3 mm and the diameter is 5-10 μm; and the length of the aramid fiber is 0.3-1 mm and the diameter is 12-18 μm.

[0010] Furthermore, the lubricant is calcium stearate; the coupling agent is a titanate coupling agent, and the titanate coupling agent is isopropyl tris (dioctyl pyrophosphate) titanate.

[0011] Furthermore, the modification method of the organically modified montmorillonite includes: adding sodium montmorillonite to deionized water, stirring to form a suspension with a mass fraction of 5-8%, adding hexadecyltrimethylammonium bromide at a weight ratio of 15-20% of the weight of the sodium montmorillonite, stirring and reacting at 80-90°C for 2-3 hours, filtering, washing with deionized water until the filtrate is free of bromide ions, drying at 105-110°C, and grinding through a 200-mesh sieve to obtain the obtained product.

[0012] Furthermore, the weight ratio of the organic modified montmorillonite to the graphene is (2-3):1.

[0013] Furthermore, the weight ratio of the modified high temperature resistant matrix material to the nitrile rubber is (4-6):1.

[0014] The present invention also provides a method for preparing the above-mentioned asbestos-free sealing plate, comprising the following steps: S1. Raw material pretreatment: Dry the aluminum silicate fiber and basalt fiber in an oven at 100-120°C for 2-3 hours. After drying, the moisture content is ≤0.5%. The aramid fiber was washed with deionized water until the pH value of the washing solution was 7, and dried in an oven at 80-90°C for 1-2 hours; The nitrile rubber is plasticized on an open mill at a plasticizing temperature of 50-60°C, a roller distance of 0.5-1mm, and a plasticizing time of 10-15 minutes; Graphene was added to anhydrous ethanol and ultrasonically dispersed at a power of 300-400 W for 30-40 minutes to prepare a graphene dispersion with a concentration of 0.5-1.5 mg / mL; S2 hybrid fiber preparation: The pretreated aluminum silicate fiber, basalt fiber and aramid fiber were added to a high-speed mixer, a lubricant and a coupling agent were added, and stirred at a speed of 800-1000r / min for 10-15min to obtain a hybrid fiber; S3. Preparation of the matrix mixture: Heat the modified high-temperature-resistant matrix material to 60-70°C, add the plasticized nitrile rubber (chopped into 5-10 mm particles), environmentally friendly flame retardant, organic modified montmorillonite, and graphene dispersion, and stir at 500-600 r / min for 20-30 minutes. During stirring, control the temperature at 65-75°C to completely evaporate the anhydrous ethanol to obtain a matrix mixture. S4 composite material mixing: The mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3 and stirred at a speed of 700-800r / min for 30-40min to obtain a uniform composite material; S5. Molding and curing: Place the composite material obtained in step S4 in a mold with a 5-10μm polytetrafluoroethylene emulsion release agent applied to the inner wall, cold press mold it at a pressure of 15-25MPa, and hold the pressure for 10-15min to obtain a slab; place the slab in a curing furnace, first heat it to 120-130℃ at a rate of 5℃ / min, keep it warm for 2-3h, then heat it to 180-200℃ at a rate of 3℃ / min, keep it warm for 1-2h, and naturally cool it to room temperature to obtain an asbestos-free sealing board.

[0015] Furthermore, in step S1, 0.5-1 parts by weight of a vulcanization accelerator is added to the nitrile rubber during the mastication process. The vulcanization accelerator is tetramethylthiuram disulfide, and the mastication is continued for 5 minutes after the addition.

[0016] The beneficial effects of this technical solution are: (1) The present invention strictly complies with environmental protection requirements. The raw material system does not contain asbestos, formaldehyde, and heavy metal elements such as lead, cadmium, and mercury. The magnesium hydroxide flame retardant used is inorganic and environmentally friendly, with no halogen release risk. The silane coupling agent and lubricant are both low-volatility environmentally friendly additives, which comply with RoHS2.0 and REACH regulations. The product does not emit toxic and harmful substances during the entire process of production, use, and disposal, avoiding the environmental risks of traditional sealing materials from the source, and can meet the needs of high-end environmental protection scenarios such as food grade and medical grade.

[0017] (2) A breakthrough in high-temperature resistance is achieved through multi-dimensional collaborative design. Aluminum silicate fiber and basalt fiber form a high-temperature resistant skeleton. The modified epoxy resin has good thermal stability after being treated with a silane coupling agent. Nitrile rubber further enhances heat resistance. The synergistic effect of the three enables the sealing plate to be used stably for a long time in an environment of 200-250℃, and the short-term temperature resistance can reach 300℃, meeting the sealing needs of high-temperature industrial equipment.

[0018] (3) The "inorganic-organic" fiber synergistic reinforcement mechanism is adopted. The inorganic composite fiber provides rigid support, and the aramid fiber improves the toughness of the material. After being treated with a coupling agent, the fiber and the matrix interface are tightly bonded, so that the sealing plate has good tensile strength and compression rebound rate. At the same time, the lamellar structure of the organic modified montmorillonite and the two-dimensional nano effect of graphene form a dense barrier network with excellent gas barrier properties, which can still maintain reliable sealing under high-pressure conditions.

[0019] (4) Through molecular design to optimize interfacial compatibility, the silane coupling agent simultaneously modifies the epoxy resin and the inorganic fiber surface to form a chemical bridging effect. The alkyl chain of the organically modified montmorillonite produces an affinity with the polar group of the nitrile rubber. The graphene is evenly embedded in the matrix after ultrasonic dispersion, effectively suppressing the internal stress concentration of the material. After multiple hot and cold cycle tests, the product has no cracks or stratification, stable performance, and greatly extended service life.

[0020] (5) The parameters of the preparation method of the present invention are clear and easy to control. The fiber moisture content and rubber plasticization degree are precisely controlled in the raw material pretreatment stage to ensure the uniformity of the material. The mixing stage adopts gradient speed stirring to avoid fiber damage while achieving uniform dispersion. The curing stage adopts a step-by-step temperature increase system to reduce the generation of internal stress. The entire process does not require special equipment and can be modified and produced using the existing sealing plate production line. The equipment investment cost is low, suitable for large-scale mass production, and has significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a comparative table of the composition differences of an asbestos-free sealing board and its preparation method proposed in the present invention; Figure 2 This is a comparison table of experimental data of an asbestos-free sealing plate and its preparation method proposed in the present invention; Figure 3 This is a comparison table of the preparation differences of an asbestos-free sealing plate and its preparation method proposed in the present invention. DETAILED DESCRIPTION

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

[0023] The specific implementation process is as follows: Raw materials preparation: Inorganic composite fibers: aluminum silicate fibers (length 0.5-2 mm, diameter 3-8 μm), basalt fibers (length 1-3 mm, diameter 5-10 μm); Organic reinforcing fiber: aramid fiber (length 0.3-1mm, diameter 12-18μm), aramid fiber is poly(p-phenylene terephthalamide) fiber; Modified high-temperature resistant matrix material: epoxy resin modified with γ-aminopropyltriethoxysilane. The epoxy resin used in the modified high-temperature resistant matrix material is bisphenol A epoxy resin, and the specific model is E-51. The modification process is to heat the epoxy resin to 80-90°C, add γ-aminopropyltriethoxysilane at a weight ratio of 3-5% of the epoxy resin under stirring, and after the addition is completed, keep the mixture warm and stir for 1-2 hours, and then cool it to room temperature. Nitrile rubber: Acrylonitrile content 25-35%, Mooney viscosity (ML1+4, 100℃) 40-60; Environmentally friendly flame retardant: magnesium hydroxide, particle size 1-5μm; Lubricant: calcium stearate; Coupling agent: isopropyl tris (dioctyl pyrophosphate) titanate; Organically modified montmorillonite: sodium montmorillonite modified with hexadecyltrimethylammonium bromide, with an interlayer spacing of 2.5-3.5 nm. The modification method comprises adding sodium montmorillonite to deionized water and stirring to form a suspension with a mass fraction of 5-8%. Hexadecyltrimethylammonium bromide at a concentration of 15-20% by weight of the sodium montmorillonite is then added, stirring and reacting at 80-90°C for 2-3 hours. The mixture is then filtered and washed with deionized water until the filtrate is free of bromide ions (no white precipitate is detected using a silver nitrate solution). The mixture is then dried at 105-110°C and ground through a 200-mesh sieve. Graphene: flake graphene, thickness 0.5-2nm, flake diameter 5-10μm; Vulcanization accelerator: tetramethylthiuram disulfide.

[0024] Example 1: See also Figure 1-3 The present invention provides a technical solution: an asbestos-free sealing plate, made of the following raw materials in actual mass: 20 kg of inorganic composite fiber (14 kg of aluminum silicate fiber, 6 kg of basalt fiber), 5 kg of organic reinforcing fiber, 35 kg of modified high-temperature resistant matrix material, 5 kg of nitrile rubber, 8 kg of environmentally friendly flame retardant, 1 kg of lubricant, 1 kg of coupling agent, 3 kg of organic modified montmorillonite, and 1 kg of graphene; The preparation method is as follows: S1. Raw material pretreatment: Aluminum silicate fiber and basalt fiber were dried in an oven at 100°C for 3 h, with a moisture content of 0.4% after drying. Aramid fiber was washed with deionized water until the pH of the washing solution reached 7 and then dried in an oven at 80°C for 2 h. Nitrile rubber was masticated on an open mill at 50°C, a roll gap of 0.5 mm, and a mastication time of 15 min. Graphene was added to anhydrous ethanol and ultrasonically dispersed at 300 W for 40 min to prepare a graphene dispersion with a concentration of 0.5 mg / mL. S2. Preparation of hybrid fibers: The pretreated aluminum silicate fibers, basalt fibers, and aramid fibers were added to a high-speed mixer, a lubricant and a coupling agent were added, and the mixture was stirred at a speed of 800 r / min for 15 min to obtain a hybrid fiber. S3. Preparation of the matrix mixture: The modified high-temperature-resistant matrix material was heated to 60°C, and plasticized nitrile rubber (chopped into 5 mm particles), an environmentally friendly flame retardant, organically modified montmorillonite, and a graphene dispersion were added. The mixture was stirred at 500 r / min for 30 min. During the stirring process, the temperature was maintained at 65°C to allow complete evaporation of the anhydrous ethanol to obtain a matrix mixture. S4 composite material mixing: The mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3 and stirred at a speed of 700r / min for 40min to obtain a uniform composite material; S5. Molding and curing: The composite material obtained in step S4 is placed in a mold with a 5μm polytetrafluoroethylene emulsion release agent applied to the inner wall, and cold-pressed at a pressure of 15MPa for 15min to obtain a slab; the slab is placed in a curing oven, first heated to 120°C at a rate of 5°C / min, kept warm for 3h, then heated to 180°C at a rate of 3°C / min, kept warm for 2h, and naturally cooled to room temperature to obtain an asbestos-free sealing plate; The amount of each component in the raw material ratio of the sealing plate prepared in this embodiment is within a relatively low range. Through a reasonable preparation process, the sealing plate has certain high temperature resistance and sealing properties; after testing, it has certain tensile strength and compression rebound rate, good thermal stability at 200°C, and a low gas leakage rate; the inorganic composite fiber, organic reinforced fiber and matrix material are closely combined, basically meeting the sealing requirements under general working conditions, but there is room for improvement in performance under higher temperature and pressure environments.

[0025] Example 2: See also Figure 1-3The present invention provides a technical solution: an asbestos-free sealing plate, made of the following raw materials in actual mass: 25 kg of inorganic composite fiber (18 kg of aluminum silicate fiber, 7 kg of basalt fiber), 7 kg of organic reinforcing fiber, 40 kg of modified high-temperature resistant matrix material, 7 kg of nitrile rubber, 12 kg of environmentally friendly flame retardant, 2 kg of lubricant, 1.5 kg of coupling agent, 4.5 kg of organic modified montmorillonite, and 2 kg of graphene; The preparation method is as follows: S1. Raw material pretreatment: Aluminum silicate fiber and basalt fiber were dried in an oven at 110°C for 2.5 hours, and the moisture content after drying was 0.3%; aramid fiber was washed with deionized water until the pH value of the washing solution was 7, and then dried in an oven at 85°C for 1.5 hours; nitrile rubber was masticated on an open mill at a mastication temperature of 55°C, a roller gap of 0.8 mm, and a mastication time of 12 minutes. During the mastication process, 0.7 kg of tetramethylthiuram disulfide, a vulcanization accelerator, was added, and mastication was continued for 5 minutes after addition; graphene was added to anhydrous ethanol and ultrasonically dispersed at a power of 350 W for 35 minutes to prepare a graphene dispersion with a concentration of 1 mg / mL; S2. Preparation of hybrid fibers: The pretreated aluminum silicate fibers, basalt fibers, and aramid fibers were added to a high-speed mixer, a lubricant and a coupling agent were added, and the mixture was stirred at a speed of 900 r / min for 12 min to obtain a hybrid fiber. S3. Preparation of the matrix mixture: The modified high-temperature-resistant matrix material was heated to 65°C, and plasticized nitrile rubber (chopped into 8 mm particles), an environmentally friendly flame retardant, organically modified montmorillonite, and a graphene dispersion were added. The mixture was stirred at 550 r / min for 25 minutes. During the stirring process, the temperature was maintained at 70°C to allow complete evaporation of the anhydrous ethanol to obtain a matrix mixture. S4 composite material mixing: The mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3 and stirred at a speed of 750r / min for 35min to obtain a uniform composite material; S5. Molding and curing: The composite material obtained in step S4 is placed in a mold with an inner wall coated with an 8μm polytetrafluoroethylene emulsion release agent, and cold-pressed at a pressure of 20MPa for 12min to obtain a slab; the slab is placed in a curing oven, first heated to 125°C at a rate of 5°C / min, kept warm for 2.5h, then heated to 190°C at a rate of 3°C / min, kept warm for 1.5h, and naturally cooled to room temperature to obtain an asbestos-free sealing plate; This embodiment optimizes the raw material ratio and preparation process. The ratio of organic modified montmorillonite to graphene is appropriate, and the addition of vulcanization accelerator improves the performance of nitrile rubber. After testing, the tensile strength and compression rebound rate of the sealing plate are improved compared with Example 1, the thermal stability is good at 220°C, and the gas leakage rate is further reduced. The prepared sealing plate has significantly improved high temperature resistance, good mechanical strength and sealing, good compatibility between the various components, and better comprehensive performance than Example 1, and can be used in medium and high temperature working conditions.

[0026] Example 3: See also Figure 1-3 The present invention provides a technical solution: an asbestos-free sealing plate, made of the following raw materials in actual mass: 28 kg of inorganic composite fiber (20 kg of aluminum silicate fiber, 8 kg of basalt fiber), 9 kg of organic reinforcing fiber, 42 kg of modified high-temperature resistant matrix material, 8 kg of nitrile rubber, 14 kg of environmentally friendly flame retardant, 2.5 kg of lubricant, 1.8 kg of coupling agent, 5 kg of organic modified montmorillonite, and 2.5 kg of graphene; The preparation method is as follows: S1. Raw material pretreatment: Aluminum silicate fiber and basalt fiber were dried in an oven at 115°C for 2.2 hours, and the moisture content after drying was 0.2%; the aramid fiber was washed with deionized water until the pH value of the washing solution was 7, and then dried in an oven at 88°C for 1.2 hours; the nitrile rubber was masticated on an open mill at a mastication temperature of 58°C, a roller gap of 0.9 mm, and a mastication time of 11 minutes. During the mastication process, 0.9 kg of tetramethylthiuram disulfide, a vulcanization accelerator, was added, and mastication was continued for 5 minutes after addition; graphene was added to anhydrous ethanol and ultrasonically dispersed at a power of 380 W for 32 minutes to prepare a graphene dispersion with a concentration of 1.2 mg / mL; S2. Preparation of hybrid fiber: The pretreated aluminum silicate fiber, basalt fiber and aramid fiber were added to a high-speed mixer, a lubricant and a coupling agent were added, and stirred at a speed of 950 r / min for 11 min to obtain a hybrid fiber; S3. Preparation of the matrix mixture: The modified high-temperature-resistant matrix material was heated to 68°C, and plasticized nitrile rubber (chopped into 9 mm particles), an environmentally friendly flame retardant, organically modified montmorillonite, and a graphene dispersion were added. The mixture was stirred at 580 r / min for 22 min. During the stirring process, the temperature was maintained at 72°C to allow complete evaporation of the anhydrous ethanol to obtain a matrix mixture. S4 composite material mixing: The mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3 and stirred at a speed of 780r / min for 32min to obtain a uniform composite material; S5. Molding and curing: The composite material obtained in step S4 is placed in a mold with a 9μm polytetrafluoroethylene emulsion release agent applied to the inner wall, and cold-pressed at a pressure of 23MPa for 11min to obtain a slab; the slab is placed in a curing oven, first heated to 128°C at a rate of 5°C / min, kept warm for 2.2h, then heated to 195°C at a rate of 3°C / min, kept warm for 1.2h, and naturally cooled to room temperature to obtain an asbestos-free sealing plate; This embodiment further adjusts the raw material ratio, increases the amount of inorganic composite fiber and organic reinforcing fiber, and optimizes process parameters such as stirring speed and temperature; after testing, the tensile strength and compression rebound rate of the sealing plate are further improved compared with Example 2, the thermal stability at 230°C is excellent, and the gas leakage rate is significantly reduced; the structure of the sealing plate is more compact, and the high temperature resistance and mechanical properties are further improved. It can still maintain a good sealing effect under higher temperature and pressure conditions, and is suitable for high temperature and high pressure conditions.

[0027] Example 4: See also Figure 1-3 The present invention provides a technical solution: an asbestos-free sealing plate, made of the following raw materials in actual mass: 30 kg of inorganic composite fiber (22 kg of aluminum silicate fiber, 8 kg of basalt fiber), 10 kg of organic reinforcing fiber, 45 kg of modified high-temperature resistant matrix material, 10 kg of nitrile rubber, 15 kg of environmentally friendly flame retardant, 3 kg of lubricant, 2 kg of coupling agent, 6 kg of organic modified montmorillonite, and 3 kg of graphene; The preparation method is as follows: S1. Raw material pretreatment: Aluminum silicate fiber and basalt fiber were dried in an oven at 120°C for 2 h, with a moisture content of 0.1% after drying; aramid fiber was washed with deionized water until the pH value of the washing solution reached 7, and then dried in an oven at 90°C for 1 h; nitrile rubber was masticated on an open mill at a temperature of 60°C, a roller gap of 1 mm, and a mastication time of 10 min. During the mastication process, 1 kg of tetramethylthiuram disulfide, a vulcanization accelerator, was added, and mastication was continued for 5 min after addition; graphene was added to anhydrous ethanol and ultrasonically dispersed at a power of 400 W for 30 min to prepare a graphene dispersion with a concentration of 1.5 mg / mL; S2. Preparation of hybrid fibers: The pretreated aluminum silicate fibers, basalt fibers, and aramid fibers were added to a high-speed mixer, a lubricant and a coupling agent were added, and the mixture was stirred at a speed of 1000 r / min for 10 min to obtain a hybrid fiber. S3. Preparation of the matrix mixture: The modified high-temperature-resistant matrix material was heated to 70°C, and plasticized nitrile rubber (chopped into 10 mm particles), an environmentally friendly flame retardant, organically modified montmorillonite, and a graphene dispersion were added. The mixture was stirred at 600 r / min for 20 min. During the stirring process, the temperature was maintained at 75°C to completely evaporate the anhydrous ethanol, thereby obtaining a matrix mixture. S4 composite material mixing: The mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3 and stirred at a speed of 800r / min for 30min to obtain a uniform composite material; S5. Molding and curing: The composite material obtained in step S4 is placed in a mold with a 10 μm polytetrafluoroethylene emulsion release agent applied to the inner wall, and cold-pressed at a pressure of 25 MPa for 10 min to obtain a slab; the slab is placed in a curing oven, first heated to 130°C at a rate of 5°C / min, kept warm for 2 h, then heated to 200°C at a rate of 3°C / min, kept warm for 1 h, and naturally cooled to room temperature to obtain an asbestos-free sealing plate; This embodiment uses the highest proportion of raw materials, and the process parameters are also in the optimized range; after testing, the sealing plate has the highest tensile strength and compression rebound rate, good thermal stability under long-term use at 250°C, and extremely low gas leakage rate; the synergistic effect between the raw materials is fully exerted, the material has excellent density and uniformity, and the overall performance is the best, which can meet the sealing requirements of high-end high-temperature and high-pressure equipment.

[0028] Example 5: See also Figure 1-3 The present invention provides a technical solution: an asbestos-free sealing plate, made of the following raw materials in actual mass: 22kg of inorganic composite fiber (16kg of aluminum silicate fiber, 6kg of basalt fiber), 6kg of organic reinforcing fiber, 38kg of modified high-temperature resistant matrix material, 6kg of nitrile rubber, 10kg of environmentally friendly flame retardant, 1.5kg of lubricant, 1.2kg of coupling agent, 3.5kg of organic modified montmorillonite, and 1.5kg of graphene; The preparation method is as follows: S1. Raw material pretreatment: Aluminum silicate fiber and basalt fiber were dried in an oven at 105°C for 2.8 hours, and the moisture content after drying was 0.35%; the aramid fiber was washed with deionized water until the pH value of the washing solution was 7, and then dried in an oven at 82°C for 1.8 hours; the nitrile rubber was masticated on an open mill at a mastication temperature of 52°C, a roller gap of 0.6 mm, and a mastication time of 14 minutes. During the mastication process, 0.6 kg of tetramethylthiuram disulfide, a vulcanization accelerator, was added, and mastication was continued for 5 minutes after addition; graphene was added to anhydrous ethanol and ultrasonically dispersed at a power of 320 W for 38 minutes to prepare a graphene dispersion with a concentration of 0.8 mg / mL; S2. Preparation of hybrid fiber: The pretreated aluminum silicate fiber, basalt fiber and aramid fiber were added to a high-speed mixer, a lubricant and a coupling agent were added, and stirred at a speed of 850 r / min for 14 min to obtain a hybrid fiber; S3. Preparation of the matrix mixture: The modified high-temperature-resistant matrix material was heated to 62°C, and plasticized nitrile rubber (chopped into 6 mm particles), an environmentally friendly flame retardant, organically modified montmorillonite, and a graphene dispersion were added. The mixture was stirred at 520 r / min for 28 minutes. During the stirring process, the temperature was maintained at 67°C to allow complete evaporation of the anhydrous ethanol to obtain a matrix mixture. S4 composite material mixing: The mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3 and stirred at a speed of 720r / min for 38min to obtain a uniform composite material; S5. Molding and curing: The composite material obtained in step S4 is placed in a mold with a 6μm polytetrafluoroethylene emulsion release agent applied to the inner wall, and cold-pressed at a pressure of 17MPa for 14min to obtain a slab; the slab is placed in a curing oven, first heated to 122°C at a rate of 5°C / min, kept warm for 2.8h, then heated to 185°C at a rate of 3°C / min, kept warm for 1.8h, and naturally cooled to room temperature to obtain an asbestos-free sealing plate; In this embodiment, the raw material dosage is moderate and the process parameters are reasonably set. After testing, the sealing plate has good tensile strength and compression rebound rate, good thermal stability at 210°C, and low gas leakage rate. The combination of fibers and the matrix is ​​relatively uniform, and there are no obvious pores inside the material. It can meet the sealing requirements of medium temperature and pressure conditions and has high cost performance.

[0029] Example 6: See also Figure 1-3 The present invention provides a technical solution: an asbestos-free sealing plate, made of the following raw materials in actual mass: 26 kg of inorganic composite fiber (19 kg of aluminum silicate fiber, 7 kg of basalt fiber), 8 kg of organic reinforcing fiber, 41 kg of modified high-temperature resistant matrix material, 9 kg of nitrile rubber, 13 kg of environmentally friendly flame retardant, 2.2 kg of lubricant, 1.7 kg of coupling agent, 5.5 kg of organic modified montmorillonite, and 2.8 kg of graphene; The preparation method is as follows: S1. Raw material pretreatment: Aluminum silicate fiber and basalt fiber were dried in an oven at 118°C for 2.1 hours, and the moisture content after drying was 0.25%; the aramid fiber was washed with deionized water until the pH value of the washing solution was 7, and dried in an oven at 89°C for 1.1 hours; the nitrile rubber was masticated on an open mill at a mastication temperature of 59°C, a roller gap of 0.95 mm, and a mastication time of 10.5 minutes. During the mastication process, 0.95 kg of tetramethylthiuram disulfide, a vulcanization accelerator, was added, and mastication was continued for 5 minutes after addition; graphene was added to anhydrous ethanol and ultrasonically dispersed at a power of 390 W for 31 minutes to prepare a graphene dispersion with a concentration of 1.4 mg / mL; S2. Preparation of hybrid fiber: The pretreated aluminum silicate fiber, basalt fiber and aramid fiber were added to a high-speed mixer, a lubricant and a coupling agent were added, and stirred at a speed of 980 r / min for 10.5 min to obtain a hybrid fiber; S3. Preparation of the matrix mixture: The modified high-temperature-resistant matrix material was heated to 69°C, and plasticized nitrile rubber (chopped into 9.5 mm particles), an environmentally friendly flame retardant, organically modified montmorillonite, and a graphene dispersion were added. The mixture was stirred at 590 r / min for 21 min. The temperature was maintained at 74°C during stirring to allow complete evaporation of the anhydrous ethanol, to obtain a matrix mixture. S4 composite material mixing: The mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3 and stirred at a speed of 790r / min for 31min to obtain a uniform composite material; S5. Molding and curing: The composite material obtained in step S4 is placed in a mold with a 9.5 μm polytetrafluoroethylene emulsion release agent applied to the inner wall, and cold-pressed at a pressure of 24 MPa for 10.5 min to obtain a slab; the slab is placed in a curing oven, first heated to 129 ° C at a rate of 5 ° C / min, kept warm for 2.1 h, then heated to 198 ° C at a rate of 3 ° C / min, kept warm for 1.1 h, and naturally cooled to room temperature to obtain an asbestos-free sealing plate; This embodiment has made fine adjustments to the raw material ratio and process parameters, and the amount of organic modified montmorillonite and graphene used is relatively high. After testing, the density of the sealing plate is significantly improved, the tensile strength and compression rebound rate are excellent, the thermal stability at 240°C is outstanding, and the gas leakage rate is extremely low. The comprehensive performance of the material is close to that of Example 4, and it is suitable for high-temperature working conditions with high requirements for sealing performance.

[0030] Example 7: See also Figure 1-3 The present invention provides a technical solution: an asbestos-free sealing plate, made of the following raw materials in actual mass: 23kg of inorganic composite fiber (17kg of aluminum silicate fiber, 6kg of basalt fiber), 7kg of organic reinforcing fiber, 39kg of modified high-temperature resistant matrix material, 7kg of nitrile rubber, 11kg of environmentally friendly flame retardant, 1.8kg of lubricant, 1.4kg of coupling agent, 4kg of organic modified montmorillonite, and 2kg of graphene; The preparation method is as follows: S1. Raw material pretreatment: Aluminum silicate fiber and basalt fiber were dried in an oven at 108°C for 2.6 hours, with a moisture content of 0.3% after drying; aramid fiber was washed with deionized water until the pH value of the washing solution was 7 and dried in an oven at 84°C for 1.6 hours; nitrile rubber was masticated on an open mill at a mastication temperature of 54°C, a roller gap of 0.7 mm, and a mastication time of 13 minutes. During the mastication process, 0.7 kg of tetramethylthiuram disulfide, a vulcanization accelerator, was added, and mastication was continued for 5 minutes after addition; graphene was added to anhydrous ethanol and ultrasonically dispersed at a power of 340 W for 36 minutes to prepare a graphene dispersion with a concentration of 1 mg / mL; S2. Preparation of hybrid fiber: The pretreated aluminum silicate fiber, basalt fiber and aramid fiber were added to a high-speed mixer, a lubricant and a coupling agent were added, and stirred at a speed of 880 r / min for 13 min to obtain a hybrid fiber; S3. Preparation of the matrix mixture: The modified high-temperature-resistant matrix material was heated to 64°C, and plasticized nitrile rubber (chopped into 7 mm particles), an environmentally friendly flame retardant, organically modified montmorillonite, and a graphene dispersion were added. The mixture was stirred at 540 r / min for 26 minutes. During the stirring process, the temperature was maintained at 68°C to allow complete evaporation of the anhydrous ethanol, to obtain a matrix mixture. S4 composite material mixing: The mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3 and stirred at a speed of 740r / min for 36min to obtain a uniform composite material; S5. Molding and curing: The composite material obtained in step S4 is placed in a mold with a 7μm polytetrafluoroethylene emulsion release agent applied to the inner wall, and cold-pressed at a pressure of 19MPa for 13min to obtain a slab; the slab is placed in a curing oven, first heated to 124°C at a rate of 5°C / min, kept warm for 2.6h, then heated to 190°C at a rate of 3°C / min, kept warm for 1.6h, and naturally cooled to room temperature to obtain an asbestos-free sealing plate; The raw material ratio in this embodiment is balanced and the process parameters are reasonably set. After testing, the tensile strength, compression rebound rate and thermal stability of the sealing plate are all good. The performance is stable when used at 220°C and the gas leakage rate is low. The fibers are evenly dispersed in the matrix, and the mechanical properties and sealing properties of the material are coordinated and unified, which is suitable for promotion and application in various industrial scenarios.

[0031] Example 8: See also Figure 1-3The present invention provides a technical solution: an asbestos-free sealing plate, made of the following raw materials in actual mass: 29 kg of inorganic composite fiber (21 kg of aluminum silicate fiber, 8 kg of basalt fiber), 9.5 kg of organic reinforcing fiber, 44 kg of modified high-temperature resistant matrix material, 9.5 kg of nitrile rubber, 14.5 kg of environmentally friendly flame retardant, 2.8 kg of lubricant, 1.9 kg of coupling agent, 5.8 kg of organic modified montmorillonite, and 2.9 kg of graphene; The preparation method is as follows: S1. Raw material pretreatment: Aluminum silicate fiber and basalt fiber were dried in an oven at 119°C for 2.05 h, and the moisture content after drying was 0.15%; the aramid fiber was washed with deionized water until the pH value of the washing solution was 7, and then dried in an oven at 89.5°C for 1.05 h; the nitrile rubber was masticated on an open mill at a mastication temperature of 59.5°C, a roller gap of 0.98 mm, and a mastication time of 10.2 min. During the mastication process, 0.98 kg of tetramethylthiuram disulfide, a vulcanization accelerator, was added, and mastication was continued for 5 min after addition; graphene was added to anhydrous ethanol and ultrasonically dispersed at a power of 395 W for 30.5 min to prepare a graphene dispersion with a concentration of 1.45 mg / mL; S2. Preparation of hybrid fiber: The pretreated aluminum silicate fiber, basalt fiber and aramid fiber were added to a high-speed mixer, a lubricant and a coupling agent were added, and stirred at a speed of 990 r / min for 10.2 min to obtain a hybrid fiber; S3. Preparation of the matrix mixture: The modified high-temperature-resistant matrix material was heated to 69.5°C, and plasticized nitrile rubber (chopped into 9.8 mm particles), an environmentally friendly flame retardant, organically modified montmorillonite, and a graphene dispersion were added. The mixture was stirred at 595 r / min for 20.5 min. During the stirring process, the temperature was maintained at 74.5°C to allow complete volatilization of the anhydrous ethanol, to obtain a matrix mixture. S4 composite material mixing: The mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3 and stirred at a speed of 795r / min for 30.5min to obtain a uniform composite material; S5. Molding and curing: The composite material obtained in step S4 is placed in a mold with an inner wall coated with a 9.8 μm polytetrafluoroethylene emulsion release agent, and cold-pressed at a pressure of 24.5 MPa for 10.2 min to obtain a slab; the slab is placed in a curing oven, first heated to 129.5 ° C at a rate of 5 ° C / min, kept warm for 2.05 h, then heated to 198 ° C at a rate of 3 ° C / min, kept warm for 1.05 h, and naturally cooled to room temperature to obtain an asbestos-free sealing plate; The raw material dosage in this embodiment is close to the maximum value, and the process parameters are highly refined. After testing, the tensile strength and compression rebound rate of the sealing plate are extremely high, the long-term thermal stability at 250°C is excellent, and the gas leakage rate is extremely low. The internal structure of the material is uniform and dense, the various components work together fully, and the comprehensive performance reaches the optimal level, which can meet the sealing requirements of extreme high temperature and high pressure working conditions.

[0032] Comparative Example 1: See also Figure 1-3 The present invention provides a comparative technical solution: an asbestos-free sealing plate, made of the following raw materials in actual mass: 25 kg of inorganic composite fiber (18 kg of aluminum silicate fiber, 7 kg of basalt fiber), 7 kg of organic reinforcing fiber, 40 kg of unmodified epoxy resin, 12 kg of environmentally friendly flame retardant, 2 kg of lubricant, and 1.5 kg of coupling agent; The preparation method is as follows: S1. Raw material pretreatment: Aluminum silicate fiber and basalt fiber were dried in an oven at 110°C for 2.5 hours, with a moisture content of 0.3% after drying. Aramid fiber was washed with deionized water to a pH of 7 and then dried in an oven at 85°C for 1.5 hours. S2. Preparation of hybrid fibers: The pretreated aluminum silicate fibers, basalt fibers, and aramid fibers were added to a high-speed mixer, a lubricant and a coupling agent were added, and the mixture was stirred at a speed of 900 r / min for 12 min to obtain a hybrid fiber. S3 matrix mixture preparation: the unmodified epoxy resin was heated to 65 ° C, an environmentally friendly flame retardant was added, and stirred at a speed of 550r / min for 25min to obtain a matrix mixture; S4 composite material mixing: The mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3 and stirred at a speed of 750r / min for 35min to obtain a uniform composite material; S5. Molding and curing: The composite material obtained in step S4 is placed in a mold with an inner wall coated with an 8μm polytetrafluoroethylene emulsion release agent, and cold-pressed at a pressure of 20MPa for 12min to obtain a slab; the slab is placed in a curing oven, first heated to 125°C at a rate of 5°C / min, kept warm for 2.5h, then heated to 190°C at a rate of 3°C / min, kept warm for 1.5h, and naturally cooled to room temperature to obtain an asbestos-free sealing plate; This comparative example does not use nitrile rubber, organically modified montmorillonite, or graphene, and uses unmodified epoxy resin as the matrix material. Testing has shown that the sealing plate has low tensile strength, insufficient compression rebound rate, poor thermal stability at 200°C, and exhibits obvious softening. Due to the lack of the toughening effect of nitrile rubber and the enhanced sealing effect of montmorillonite and graphene, the material is relatively brittle, cracks appear after hot and cold cycle testing, and the gas leakage rate is high, making it unable to meet the sealing requirements of high temperature and high pressure working conditions.

[0033] Comparative Example 2: See also Figure 1-3 The present invention provides a comparative technical solution: an asbestos-free sealing plate, made of the following raw materials of actual mass: 25 kg of glass fiber, 7 kg of organic reinforcing fiber, 40 kg of modified high-temperature resistant matrix material, 7 kg of nitrile rubber, 12 kg of environmentally friendly flame retardant, 2 kg of lubricant, and 1.5 kg of coupling agent; The preparation method is as follows: S1. Raw material pretreatment: The glass fiber was dried in an oven at 110°C for 2.5h, and the moisture content after drying was 0.3%; the aramid fiber was washed with deionized water until the pH value of the washing solution was 7, and dried in an oven at 85°C for 1.5h; the nitrile rubber was masticated on an open mill at a mastication temperature of 55°C, a roller pitch of 0.8mm, and a mastication time of 12min. During the mastication process, 0.7kg of tetramethylthiuram disulfide, a vulcanization accelerator, was added and mastication was continued for 5min after addition; S2. Preparation of hybrid fiber: The pretreated glass fiber and aramid fiber were added to a high-speed mixer, a lubricant and a coupling agent were added, and stirred at a speed of 900 r / min for 12 min to obtain a hybrid fiber; S3. Preparation of the matrix mixture: The modified high-temperature resistant matrix material was heated to 65°C, and plasticized nitrile rubber (chopped into 8 mm particles) and an environmentally friendly flame retardant were added. The mixture was stirred at a speed of 550 r / min for 25 minutes to obtain a matrix mixture; S4 composite material mixing: The mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3 and stirred at a speed of 750r / min for 35min to obtain a uniform composite material; S5. Molding and curing: The composite material obtained in step S4 is placed in a mold with an inner wall coated with an 8μm polytetrafluoroethylene emulsion release agent, and cold-pressed at a pressure of 20MPa for 12min to obtain a slab; the slab is placed in a curing oven, first heated to 125°C at a rate of 5°C / min, kept warm for 2.5h, then heated to 190°C at a rate of 3°C / min, kept warm for 1.5h, and naturally cooled to room temperature to obtain an asbestos-free sealing plate; In this comparative example, glass fiber replaces the inorganic composite fiber (a mixture of aluminum silicate fiber and basalt fiber), and no organic modified montmorillonite and graphene are added. After testing, the high-temperature resistance of the sealing plate is significantly reduced, the thermal weight loss rate at 200°C is relatively high, and the tensile strength and compression rebound rate are both lower than those in Example 2. Since the heat resistance of glass fiber is not as good as that of aluminum silicate fiber and basalt fiber, and it lacks the dense barrier effect of montmorillonite and graphene, the gas leakage rate is significantly increased, and sealing failure is prone to occur when used in a high-temperature environment.

[0034] Comparative Example 3: See also Figure 1-3 The present invention provides a comparative technical solution: an asbestos-free sealing plate, made of the following raw materials in actual mass: 25 kg of inorganic composite fiber (18 kg of aluminum silicate fiber, 7 kg of basalt fiber), 7 kg of organic reinforcing fiber, 40 kg of modified high-temperature resistant matrix material, 7 kg of nitrile rubber, 12 kg of environmentally friendly flame retardant, 2 kg of lubricant, and 1.5 kg of coupling agent; The preparation method is as follows: S1. Raw material pretreatment: Aluminum silicate fiber and basalt fiber were used directly (without drying); aramid fiber was used directly (without washing and drying); nitrile rubber was used directly without plasticizing; S2. Preparation of hybrid fibers: Aluminum silicate fibers, basalt fibers, and aramid fibers were added to a high-speed mixer, a lubricant and a coupling agent were added, and the mixture was stirred at a speed of 900 r / min for 12 min to obtain a hybrid fiber. S3. Preparation of the matrix mixture: The modified high-temperature resistant matrix material was heated to 65°C, nitrile rubber (unshredded) and an environmentally friendly flame retardant were added, and the mixture was stirred at a speed of 550 r / min for 25 minutes to obtain a matrix mixture; S4 composite material mixing: the mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3, and stirred at a speed of 750r / min for 35min to obtain a composite material (there was obvious agglomeration); S5 molding and curing: The composite material obtained in step S4 is placed in a mold (without a release agent), cold-pressed at a pressure of 20 MPa, and the holding time is 12 min to obtain a slab (partially adhered to the mold); the slab is placed in a curing oven, directly heated to 190 ° C, kept warm for 3.5 h, and naturally cooled to room temperature to obtain an asbestos-free sealing plate; In this comparative example, no raw material pretreatment was performed (the fibers were not dried and cleaned, and the rubber was not plasticized). The nitrile rubber was not chopped during the preparation of the matrix mixture, and no release agent was applied during molding and curing, and a direct heating method was used. Upon testing, it was found that since the raw materials were not pretreated, there was a lot of moisture and impurities in the fibers, resulting in a high internal porosity of the material, and a significant reduction in tensile strength and compression rebound rate. The nitrile rubber was not plasticized and chopped, resulting in uneven dispersion and agglomeration, which further affected the performance. Direct heating during the curing process generated large internal stress, cracks appeared in the slab, and the mold was stuck because no release agent was applied, resulting in poor product appearance and dimensional accuracy. The comprehensive performance was far lower than that of Example 2, and could not meet actual use requirements.

[0035] See also Figure 1-3 : Examples 1-8 all employ a composite system comprising inorganic composite fibers (aluminum silicate fibers and basalt fibers in a ratio of 2-3:1), organic reinforcing fibers (aramid fibers), a modified high-temperature-resistant matrix material (epoxy resin modified with a silane coupling agent), nitrile rubber, an environmentally friendly flame retardant (magnesium hydroxide), a lubricant, a coupling agent, organically modified montmorillonite, and graphene. The raw materials complement and synergize in performance. The aluminum silicate fibers and basalt fibers form a high-temperature-resistant skeleton, the aramid fibers provide toughness support, the modified epoxy resin and nitrile rubber form a composite matrix that combines heat resistance and elasticity, the organically modified montmorillonite and graphene create a dense barrier network, and the coupling agent effectively improves the interfacial bonding between the fibers and the matrix. This multi-component synergistic effect enables the products of the examples to maintain stable mechanical and sealing properties at high temperatures of 200-250°C. For example, after long-term use at 250°C, the tensile strength and compression rebound rate of Example 4 show no significant decrease, and the gas leakage rate remains at an extremely low level. In contrast, Comparative Example 1 lacks nitrile rubber, organically modified montmorillonite and graphene, and uses unmodified epoxy resin, resulting in high brittleness and insufficient heat resistance of the material; its tensile strength is only about 60% of that of Example 2, and its thermal weight loss rate at 200°C is more than 3 times that of Example 2. After the hot and cold cycle test, obvious cracks appear, and the sealing performance drops sharply; Comparative Example 2 uses glass fiber instead of inorganic composite fiber, and does not contain montmorillonite and graphene. The heat resistance of glass fiber is lower than that of aluminum silicate fiber and basalt fiber. It is easy to undergo crystal phase transformation at high temperature, resulting in a decrease in strength. The thermal weight loss rate at 200°C is 50% higher than that of Example 2, and the gas leakage rate is 4 times that of Example 2, which cannot meet the high-temperature sealing requirements; this fully proves that the raw material system of the present invention is not a simple superposition, but through the precise selection and ratio of each component, the synergistic optimization of heat resistance, mechanical properties and sealing is achieved, overcoming the defect that a single raw material or a simple combination in the prior art cannot take into account multiple performances; In the embodiment, the two are added at a weight ratio of 2-3:1. The lamellar structure of montmorillonite can extend the gas permeation path, and the two-dimensional nano-effect of graphene can fill the pores of the material. The two synergistically form a highly efficient barrier. The gas leakage rate of Example 2 is only 1 / 3 of that of Comparative Example 1 and 1 / 4 of that of Comparative Example 2, fully demonstrating the advantages of this composite system. At the same time, the ratio of nitrile rubber to modified epoxy resin (4-6:1) has been optimized. The addition of nitrile rubber effectively improves the brittleness of the epoxy resin, while the modification treatment ensures the heat resistance of the composite matrix. The compression rebound rate of the products in the embodiment is generally more than 30% higher than that of the pure epoxy resin system (Comparative Example 1), resolving the contradiction between traditional resin-based sealing plates: "heat resistance leads to high brittleness, and good elasticity leads to poor heat resistance." The preparation process of the present invention ensures the stability and uniformity of material properties by precisely controlling the steps of raw material pretreatment, mixing and dispersion, molding and curing, which is in sharp contrast to the performance defects caused by the simplified process in the comparative example. Examples 1-8 strictly implement the raw material pretreatment steps: aluminum silicate fiber and basalt fiber are dried at 100-120°C for 2-3h to a moisture content of ≤0.5%, aramid fiber is washed to neutral and then dried, nitrile rubber is plasticized at 50-60°C (roller spacing 0.5-1mm) for 10-15min and a vulcanization accelerator is added, and graphene is ultrasonically dispersed to form a stable dispersion. These pretreatment measures effectively remove moisture and impurities in the raw materials, improve the compatibility of the fiber and the matrix, and ensure the uniformity of subsequent mixing. For example, the composite material of Example 2 has no obvious agglomeration phenomenon and the cross-sectional structure is uniform and dense. However, in Comparative Example 3, due to the lack of pretreatment, the fiber is water-carrying and the rubber is not plasticized, resulting in a high internal porosity of the material, severe agglomeration, and a tensile strength of only 50% of that of Example 2. In the mixing and molding process, the embodiment adopts a gradient speed stirring and step-by-step temperature increase curing process to further ensure performance stability. In the mixing stage, the fiber and the additive are premixed at 800-1000 r / min and then fully mixed with the matrix mixture at 700-800 r / min, which not only avoids fiber damage but also achieves uniform dispersion. During molding and curing, cold pressing is first performed (15-25 MPa, 10-15 min), and then the temperature is increased in steps (5°C / min to 120-130°C for insulation, and then 3°C / min to 180-200°C for insulation), which effectively reduces the generation of internal stress. The product of the embodiment has high dimensional accuracy, no cracks, and no deformation. However, in Comparative Example 3, the nitrile rubber is not shredded and the mixing speed is single, resulting in uneven dispersion. In addition, direct heating during curing generates huge internal stress, resulting in obvious cracks in the slab and dimensional deviation exceeding the allowable range. In Example 3, a 5-10 μm polytetrafluoroethylene emulsion release agent was applied to the inner wall of the mold before molding to ensure smooth demolding of the slab and an intact appearance. In Comparative Example 3, no release agent was applied, resulting in adhesion of the slab to the mold, which not only damaged the appearance but also affected the dimensional accuracy. Refined control of process parameters (such as the plasticating roll distance, ultrasonic power, and heating rate) minimized the performance fluctuation range of the example product, with the tensile strength deviation between different batches being ≤5%. However, due to missing or arbitrary parameters in the comparative example, the performance fluctuation exceeded 20%, and product consistency could not be guaranteed. Example 4, which uses the highest raw material dosage and optimized process parameters (120°C drying, 400W ultrasonic dispersion, 25MPa cold pressing, and step-by-step temperature curing), achieves better performance than Example 1 (lower parameters), indicating that increasing the raw material dosage and optimizing the process parameters within a reasonable range can further improve performance. Furthermore, Examples 5-8 all achieved coordinated performance improvements by adjusting the raw material ratio and process parameter combinations, demonstrating that the process of the present invention has good controllability and adaptability, and can meet the performance requirements of different scenarios through parameter adjustment. In terms of environmental performance, the raw material systems of Examples 1-8 are completely free of asbestos, formaldehyde, and heavy metals. The magnesium hydroxide flame retardant and silane coupling agent used are all environmentally friendly additives and comply with RoHS 2.0 and REACH regulations. No toxic or hazardous substances are emitted during the production process. However, some existing technologies (not reflected in the comparative examples, but a common problem in the industry) use formaldehyde-containing adhesives or heavy metal flame retardants, which pose environmental risks. The present invention solves this problem from the source and can meet the needs of high-end environmental protection fields such as food and medicine. The product of the embodiment can be used stably for a long time at 200-250°C and can withstand temperatures of up to 300°C in the short term. However, Comparative Example 1, due to the absence of nitrile rubber and unmodified epoxy resin, shows obvious softening at 200°C. Comparative Example 2 uses glass fiber instead of high-temperature resistant inorganic composite fiber, and the thermal weight loss rate at 200°C is significantly increased. The high-temperature performance of the embodiment is due to the synergistic effect of aluminum silicate fiber, basalt fiber and the modified matrix. After 1000 hot and cold cycle tests (-40°C to 200°C), Example 2 has no cracks or delamination, and the performance retention rate is high. However, Comparative Examples 1 and 2 show a significant performance degradation or even structural damage after the same test, demonstrating that the material of the present invention has excellent thermal stability and thermal shock resistance. The tensile strength of the product in the embodiment is generally ≥15MPa, the compression rebound rate is ≥45%, and the gas leakage rate is ≤1×10⁻ 3 Pa·m 3 / s, while the tensile strength of comparative example 1 is only 9MPa, the compression rebound rate is 30%, and the gas leakage rate is 9×10⁻ 3 Pa·m 3 / s; Due to process defects, the tensile strength of Comparative Example 3 is less than 8MPa, and the compression rebound rate is 25%, which is completely unable to meet the sealing requirements; this performance advantage is derived from the synergistic reinforcement of "inorganic-organic" fibers, the modification and optimization of the matrix, and the barrier effect of montmorillonite-graphene, which achieves a balance between strength and elasticity, and improves density and sealing, solving the problem of traditional asbestos-free sealing panels that "high strength means poor elasticity, and good elasticity means insufficient sealing".

[0036] The test method is as follows: Tensile strength test: According to GB / T1040.3-2006 "Determination of tensile properties of plastics Part 3: Test conditions for film and sheeting", the sealing plate was made into a dumbbell-shaped specimen. An electronic universal testing machine was used with a loading speed of 50 mm / min. The tensile strength and elongation at break were recorded. Five specimens were tested in each group and the average value was taken.

[0037] Compression rebound rate test: According to GB / T7759.1-2015 "Vulcanized rubber or thermoplastic rubber - Determination of compression set - Part 1: At room temperature and elevated temperature", place the sample in a compression device with a compression rate of 25%. After placing it at 23°C for 22 hours, release the pressure, measure the sample thickness after 30 minutes, and calculate the compression rebound rate.

[0038] Thermogravimetric analysis: Using a thermogravimetric analyzer (TGA), the temperature was raised from room temperature to 600°C at a heating rate of 10°C / min under a nitrogen atmosphere, and the thermal weight loss rate of the sample at 200°C, 250°C, and 300°C was recorded.

[0039] High-temperature tensile strength test: After preheating the sample in a 200°C oven for 1 hour, a tensile test was immediately performed on an electronic universal testing machine at a loading speed of 50 mm / min. The high-temperature tensile strength was recorded and compared with the room-temperature tensile strength to calculate the retention rate.

[0040] Gas leakage rate test: Use a gas leakage rate tester, install the sealing plate sample in a sealing fixture, apply a sealing pressure of 2MPa, pass nitrogen, and measure the gas leakage rate under a pressure of 0.6MPa.

[0041] Liquid sealing performance test: Place the sample in a liquid sealing test device, use kerosene as the medium, apply a pressure of 3MPa, maintain for 30min, observe whether there is leakage, and measure the leakage amount.

[0042] Asbestos content detection: According to GB / T23263-2024 "Determination of asbestos content in products", X-ray diffraction and polarizing microscopy are used to confirm the absence of asbestos.

[0043] Formaldehyde content detection: According to the desiccant method in GB / T17657-2013 "Test methods for physical and chemical properties of artificial boards and veneer artificial boards", the formaldehyde release in the sealed board is tested, and the requirement is ≤0.1mg / m 3 .

[0044] Heavy metal content detection: Inductively coupled plasma mass spectrometry (ICP-MS) is used to detect the content of heavy metals such as lead, cadmium, and mercury in accordance with GB / T26125-2011 "Determination of six restricted substances in electrical and electronic products (lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers)", which complies with the requirements of RoHS2.0 standards.

[0045] Hot and cold cycle test: Place the sample in a hot and cold cycle test chamber, and follow the cycle of -40℃ (maintain for 2h) → room temperature (maintain for 0.5h) → 200℃ (maintain for 2h) → room temperature (maintain for 0.5h). After 1000 cycles, observe whether there are cracks or delamination on the surface of the sample, and test its tensile strength and compression rebound retention rate.

[0046] Moisture and heat resistance test: Place the sample in a constant temperature and humidity chamber at 40°C and 90% relative humidity for 1000 hours. After taking it out, wipe off the surface moisture and test the changes in tensile strength and sealing performance.

[0047] The above is only an embodiment of the present invention, and common knowledge such as the specific technical solutions or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.

Claims

1. An asbestos-free sealing plate, characterized in that: The invention is prepared from the following raw materials in parts by weight: 20-30 parts of inorganic composite fiber, 5-10 parts of organic reinforcing fiber, 35-45 parts of modified high-temperature resistant matrix material, 5-10 parts of nitrile rubber, 8-15 parts of environmentally friendly flame retardant, 1-3 parts of lubricant, 1-2 parts of coupling agent, 3-6 parts of organic modified montmorillonite, and 1-3 parts of graphene; The inorganic composite fiber is a mixture of aluminum silicate fiber and basalt fiber, and the weight ratio of the two is (2-3):1; The organic reinforcing fiber is aramid fiber; the modified high-temperature resistant matrix material is an epoxy resin modified by a silane coupling agent, wherein the silane coupling agent is γ-aminopropyltriethoxysilane. The modification process is as follows: heating the epoxy resin to 80-90° C., adding γ-aminopropyltriethoxysilane dropwise at a rate of 3-5% by weight of the epoxy resin under stirring, and after the addition is completed, stirring and maintaining the temperature for 1-2 hours, and then cooling to room temperature; The aramid fiber is poly(p-phenylene terephthalamide) fiber, and the epoxy resin is bisphenol A epoxy resin; The environmentally friendly flame retardant is magnesium hydroxide, and its particle size is 1-5 μm; The organic modified montmorillonite is sodium montmorillonite modified by hexadecyltrimethylammonium bromide, and its interlayer spacing is 2.5-3.5nm; The graphene is flake graphene with a thickness of 0.5-2 nm and a flake diameter of 5-10 μm; Furthermore, the asbestos-free sealing plate does not contain formaldehyde, heavy metals or asbestos.

2. The asbestos-free sealing plate according to claim 1, characterized in that: The acrylonitrile content of the nitrile rubber is 25-35%, and the Mooney viscosity (ML1+4, 100°C) is 40-60.

3. The asbestos-free sealing plate according to claim 1, characterized in that: The length of the aluminum silicate fiber is 0.5-2 mm, and the diameter is 3-8 μm; the length of the basalt fiber is 1-3 mm, and the diameter is 5-10 μm; the length of the aramid fiber is 0.3-1 mm, and the diameter is 12-18 μm.

4. The asbestos-free sealing plate according to claim 1, characterized in that: The lubricant is calcium stearate; the coupling agent is a titanate coupling agent, and the titanate coupling agent is isopropyl tris (dioctyl pyrophosphate) titanate.

5. The asbestos-free sealing plate according to claim 1, characterized in that: The modification method of the organic modified montmorillonite comprises: adding sodium montmorillonite to deionized water, stirring to form a suspension with a mass fraction of 5-8%, adding hexadecyltrimethylammonium bromide in an amount of 15-20% by weight of the sodium montmorillonite, stirring and reacting at 80-90° C. for 2-3 hours, filtering, washing with deionized water until the filtrate is free of bromide ions, drying at 105-110° C., and grinding through a 200-mesh sieve to obtain the organic modified montmorillonite.

6. The asbestos-free sealing plate according to claim 1, characterized in that: The weight ratio of the organic modified montmorillonite to graphene is (2-3):

1.

7. The asbestos-free sealing plate according to claim 1, characterized in that: The weight ratio of the modified high-temperature resistant base material to the nitrile rubber is (4-6):

1.

8. A method for preparing an asbestos-free sealing plate, for preparing the asbestos-free sealing plate according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Raw material pretreatment: Dry the aluminum silicate fiber and basalt fiber in an oven at 100-120°C for 2-3 hours. After drying, the moisture content is ≤0.5%. The aramid fiber was washed with deionized water until the pH value of the washing solution was 7, and dried in an oven at 80-90°C for 1-2 hours; The nitrile rubber is plasticized on an open mill at a plasticizing temperature of 50-60°C, a roller distance of 0.5-1mm, and a plasticizing time of 10-15 minutes; Graphene was added to anhydrous ethanol and ultrasonically dispersed at a power of 300-400 W for 30-40 minutes to prepare a graphene dispersion with a concentration of 0.5-1.5 mg / mL; S2 hybrid fiber preparation: The pretreated aluminum silicate fiber, basalt fiber and aramid fiber were added to a high-speed mixer, a lubricant and a coupling agent were added, and stirred at a speed of 800-1000r / min for 10-15min to obtain a hybrid fiber; S3. Preparation of the matrix mixture: Heat the modified high-temperature-resistant matrix material to 60-70°C, add the plasticized nitrile rubber (chopped into 5-10 mm particles), environmentally friendly flame retardant, organic modified montmorillonite, and graphene dispersion, and stir at 500-600 r / min for 20-30 minutes. During stirring, control the temperature at 65-75°C to completely evaporate the anhydrous ethanol to obtain a matrix mixture. S4 composite material mixing: The mixed fiber obtained in step S2 was added to the matrix mixture obtained in step S3 and stirred at a speed of 700-800r / min for 30-40min to obtain a uniform composite material; S5. Molding and curing: Place the composite material obtained in step S4 in a mold with a 5-10μm polytetrafluoroethylene emulsion release agent applied to the inner wall, cold press mold it at a pressure of 15-25MPa, and hold the pressure for 10-15min to obtain a slab; place the slab in a curing furnace, first heat it to 120-130℃ at a rate of 5℃ / min, keep it warm for 2-3h, then heat it to 180-200℃ at a rate of 3℃ / min, keep it warm for 1-2h, and naturally cool it to room temperature to obtain an asbestos-free sealing board.

9. The preparation method according to claim 8, characterized in that In step S1, 0.5-1 parts by weight of a vulcanization accelerator is added during the mastication of the nitrile rubber, wherein the vulcanization accelerator is tetramethylthiuram disulfide, and mastication is continued for 5 minutes after addition.

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