High-performance anti-deformation high-temperature-resistant composite insulation paper

Abstract

The invention relates to the technical field of insulation paper, and discloses high-performance anti-deformation high-temperature-resistant composite insulation paper which is prepared from the following components: inorganic fibers, core-shell structure modified organic silicon resin emulsion, nano intercalation surface treatment mica powder, aramid fibers and an auxiliary additive, according to the high-performance anti-deformation high-temperature-resistant composite insulation paper provided by the invention, the comprehensive performance of the composite paper is remarkably improved through reasonable proportioning of all the components and special treatment of specific components. According to the composite insulation paper prepared by the invention, the inorganic fiber is used as a main framework material of the composite paper, and the basalt fiber or the ceramic fiber has high strength, high modulus and good high temperature resistance, so that a basic mechanical support is provided for the composite paper. The aramid fibers and the inorganic fibers have a synergistic effect, so that the mechanical strength and the flexibility of the composite paper are further enhanced. And the dispersing agent polyoxyethylene can effectively improve the dispersity of each component in the slurry, so that the fibers and the filler are uniformly distributed.

Description

Technical Field

[0001] The present invention relates to the technical field of insulating paper, in particular to a high-performance, deformation-resistant, high-temperature-resistant composite insulating paper. Background Art

[0002] As a key material in the field of electrical insulation, high-temperature resistant composite insulating paper is widely used in electrical equipment with high temperature and high insulation requirements, such as motors, transformers, and high-voltage electrical appliances, due to its excellent insulation performance and high-temperature resistance. It plays an indispensable role in ensuring the safe and stable operation of power systems.

[0003] As electrical equipment develops towards miniaturization and high power density, higher requirements are placed on the performance of high-temperature resistant composite insulation paper. It is not only required to maintain good insulation performance in high-temperature environments, but also required to have excellent anti-deformation ability to ensure the long-term and reliable operation of electrical equipment. However, existing high-temperature-resistant composite insulation papers still have many shortcomings in practical applications. Some composite papers are prone to deformation in high-temperature environments due to poor thermal stability, resulting in reduced insulation performance and affecting the normal operation of electrical equipment. Other composite papers, while capable of achieving certain high-temperature resistance, struggle to achieve a synergistic improvement in mechanical strength and insulation performance, making them unsuitable for use in complex operating conditions.

[0004] In addition, during the preparation process of traditional composite paper, the compatibility between the components is poor, making it difficult to form a stable network structure, which limits the further improvement of its comprehensive performance. Summary of the Invention

[0005] In view of the problems in the prior art, the present invention provides a high-performance, deformation-resistant, high-temperature-resistant composite insulating paper.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a high-performance, deformation-resistant, high-temperature-resistant composite insulating paper, comprising the following components in parts by mass: 30-50 parts of inorganic fiber, wherein the inorganic fiber is basalt fiber or ceramic fiber, with a length of 4-5 mm; 20-31 parts of core-shell structure modified silicone resin emulsion; 22-25 parts of nano-intercalated surface-treated mica powder, wherein the surface-treated mica powder is double-treated with acid washing and silane coupling agent, and nano-silica particles are inserted between the layers; 16-20 parts of aramid fiber, wherein the aramid fiber is para-aramid and has a length of 2-3 mm; Auxiliary additives: dispersant polyethylene oxide 1.5-2 parts, flame retardant aluminum hydroxide 4-8 parts.

[0007] As a further technical solution, the inorganic fiber includes: Inorganic fibers with a diameter of 1-3 μm and inorganic fibers with a diameter of 3-5 μm are mixed in a mass ratio of 1:2-2.5.

[0008] As a further technical solution, the preparation method of the core-shell structure modified silicone resin emulsion includes: Mixing methylphenyl silicone resin and glycidyltrimethoxysilane at a molar ratio of 1:0.35-0.4 under nitrogen protection, adding 0.06-0.08% of a platinum catalyst by weight of the mixture, and reacting at 82-87° C. for 4-5 hours to produce an epoxy-grafted silicone resin; The epoxy-grafted silicone resin and ethyl orthosilicate are mixed at a ratio of 1:0.28-0.4, and then diluted hydrochloric acid with a pH of 3-4, which is 12-14% by weight of the epoxy-grafted silicone resin, is added for hydrolysis and condensation for 1 hour to form an organic-inorganic hybrid network structure; During the hydrolysis and condensation process, nano-silica sol is added in a mass ratio of 3:1-1.2 and mixed evenly to obtain; The emulsion solid content is 35-40wt%.

[0009] As a further technical solution, the preparation method of the nano-intercalated surface-treated mica powder includes: Immerse the mica powder in 10% hydrochloric acid solution and ultrasonicate for 30 minutes, then wash with water until neutral; Mix the acid-washed mica powder with γ-aminopropyltriethoxysilane in a mass ratio of 10:1-1.6, disperse in anhydrous ethanol 5 times the total mass of the mixture, and stir at 60°C for 2 hours; Add nano-silica sol with a mass ratio of 20% of mica powder, stir and react at 80-88°C for 4-6 hours to allow nano-silica to be inserted between the mica powder layers, and then grind to a particle size of ≤10μm after drying.

[0010] As a further technical solution, the mixing ratio of the mica powder and the hydrochloric acid solution is 1:12-14; The frequency of the ultrasonic treatment was 40 kHz.

[0011] As a further technical solution, the method for preparing the high-performance, deformation-resistant, high-temperature-resistant composite insulating paper comprises: Gradient slurry preparation: Gradient-distributed inorganic fibers, surface-treated aramid fibers, and nano-intercalated surface-treated mica powder are evenly dispersed in water to form a three-layer graded slurry system; Composite molding: Using a multi-layer inclined mesh composite papermaking machine, control the following: the upper layer slurry flow rate is 0.6-0.9m / s, the net concentration is 0.8-1.2wt%; the middle layer slurry flow rate is 0.5-0.8m / s, the net concentration is 1.0-1.5wt%; the lower layer slurry flow rate is 0.6-0.9m / s, the net concentration is 0.8-1.2wt%; the core-shell structure modified silicone resin emulsion is sprayed between the layers, and the spraying amount is 15-20% of the fiber mass of each layer; Synergistic curing: hot pressing at 180-195°C and pressure 6-7MPa for 12-15 minutes to form a synergistically reinforced network structure between the modified silicone resin and the nano-intercalated mica powder.

[0012] As a further technical solution, the three-layer graded pulp system comprises: an upper pulp layer, inorganic fibers with a diameter of 1-3 μm account for 70-85% of the total mass of the fibers in this layer, and are pulped to a Canadian standard freeness of 380-420 ml CSF; a middle pulp layer, inorganic fibers with a diameter of 3-5 μm account for 65-80% of the total mass of the fibers in this layer, and are pulped to a Canadian standard freeness of 350-390 ml CSF; and a lower pulp layer, inorganic fibers with a diameter of 1-3 μm account for 70-85% of the total mass of the fibers in this layer, and are pulped to a Canadian standard freeness of 380-420 ml CSF.

[0013] As a further technical solution, the high-performance, deformation-resistant, high-temperature-resistant composite insulating paper has an interlayer dielectric constant gradient structure, with a surface layer dielectric constant of 3.0-3.5 and a middle layer dielectric constant of 4.0-4.5.

[0014] As a further technical solution, the volume resistivity of the high-performance anti-deformation high-temperature resistant composite insulating paper at 200°C is ≥1×10 12 Ω·cm, breakdown field strength ≥30kV / mm.

[0015] As a further technical solution, the high-performance, deformation-resistant, high-temperature-resistant composite insulation paper has a thermal expansion coefficient of ≤15ppm / °C and a thermal weight loss of ≤5% at 400°C. Beneficial effects of the present invention: The high-performance, deformation-resistant, and high-temperature-resistant composite insulating paper provided by the present invention significantly improves the comprehensive performance of the composite paper through the reasonable proportion of the components and the special treatment of specific components. In the composite insulating paper prepared by the present invention, inorganic fibers serve as the main skeleton material of the composite paper, and basalt fibers or ceramic fibers have high strength, high modulus, and good high-temperature resistance, providing basic mechanical support for the composite paper. The synergistic effect of aramid fibers and inorganic fibers further enhances the mechanical strength and flexibility of the composite paper. The dispersant polyethylene oxide can effectively improve the dispersibility of the components in the slurry, so that the fibers and fillers are evenly distributed; the flame retardant aluminum hydroxide decomposes at high temperatures to absorb heat, releases crystal water to dilute the combustible gas, and improves the flame retardant properties of the composite paper. Core-shell modified silicone resin emulsions are key components for improving the performance of composite paper. During their preparation, methylphenyl silicone resin reacts with epoxypropyltrimethoxysilane to form an epoxy-grafted silicone resin, imparting excellent reactivity. Hydrolysis and condensation with ethyl orthosilicate form an organic-inorganic hybrid network, enhancing the resin's heat resistance and mechanical strength. The addition of nanosilica sol further optimizes the network structure, improving the resin's hardness and wear resistance. During the composite paper preparation process, the emulsion forms a continuous resin film between layers, tightly bonding the components together. Simultaneously, its organic-inorganic hybrid network interacts with the nano-intercalated surface-treated mica powder to form a synergistically reinforced network, effectively improving the composite paper's deformation resistance and high-temperature resistance. Nano-intercalated surface-treated mica powder undergoes a dual treatment of acid washing and silane coupling agent treatment, and is intercalated with nano-silica particles, significantly improving the compatibility between the mica powder and the resin matrix. Acid washing removes impurities from the mica powder surface, while the silane coupling agent forms chemical bonds on the mica powder surface, enhancing interfacial adhesion. The nano-silica particles are inserted between the mica powder layers, increasing the interlayer spacing and improving the powder's flexibility and dispersibility. In composite paper, the nano-intercalated surface-treated mica powder is evenly dispersed within the resin matrix, providing reinforcement and toughening. Its layered structure effectively hinders heat transfer and crack propagation, further enhancing the composite paper's high-temperature resistance and mechanical properties. Through gradient slurry preparation and a multi-layer oblique mesh composite papermaking process, the composite paper develops an interlayer dielectric constant gradient structure and a unique fiber distribution, optimizing both its electrical and mechanical properties. The resulting composite paper exhibits high volume resistivity and breakdown field strength at 200°C, a low coefficient of thermal expansion, and minimal thermal weight loss at high temperatures. It also exhibits excellent deformation resistance, high-temperature resistance, and insulation properties, meeting the demands of modern electrical equipment for high-performance insulation materials. DETAILED DESCRIPTION

[0016] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0017] Example 1 Raw material formula (by mass): Basalt fiber (diameter 1-3μm:3-5μm=1:2, length 4-5mm): 30 parts Core-shell structure modified silicone resin emulsion (solid content 35wt%): 20 parts Nano-intercalated surface treated mica powder: 22 parts Para-aramid fiber (length 2-3mm): 16 parts Polyethylene oxide dispersant: 1.5 parts Aluminum hydroxide flame retardant: 4 parts Preparation process: Preparation of core-shell structure modified silicone resin emulsion: Methylphenyl silicone resin (phenyl content 45%) and epoxypropyltrimethoxysilane were mixed in a molar ratio of 1:0.35, 0.06% platinum catalyst was added, and the mixture was reacted at 82°C under nitrogen protection for 4 hours to generate epoxy-grafted silicone resin.

[0018] The above resin was mixed with ethyl orthosilicate at a ratio of 1:0.28, and diluted hydrochloric acid with a pH of 3, which was 12% of the resin mass, was added for hydrolysis and condensation for 1 hour. During this period, nano-silica sol was added at a mass ratio of 3:1 to form a core-shell structure emulsion.

[0019] Preparation of nano-intercalated surface treated mica powder: The mica powder was immersed in 10% hydrochloric acid solution (mica powder: hydrochloric acid solution = 1:12), ultrasonically treated at 40 kHz for 30 minutes, and then washed with water until neutral.

[0020] The acid-washed mica powder and γ-aminopropyltriethoxysilane were dispersed in 5 times anhydrous ethanol at a mass ratio of 10:1 and stirred at 60°C for 2 hours.

[0021] Add nano-silica sol with a mass ratio of 20% of mica powder, stir and react at 80°C for 4 hours, and then dry and crush to a particle size of ≤10μm.

[0022] Preparation of a high-performance, anti-deformation, high-temperature resistant composite insulation paper: Gradient slurry preparation: Upper slurry: 70% basalt fiber with a diameter of 1-3 μm, beaten to Canadian standard freeness of 380 ml CSF; Middle layer slurry: 65% basalt fiber with a diameter of 3-5μm, beaten to Canadian standard freeness of 350mlCSF; Lower slurry: 70% basalt fiber with a diameter of 1-3 μm, beaten to Canadian standard freeness 380 ml CSF.

[0023] Composite molding: The flow rate of the upper slurry is 0.6m / s, and the concentration on the net is 0.8wt%; The flow rate of the middle layer slurry is 0.5m / s, and the concentration on the net is 1.0wt%; The flow rate of the lower layer slurry is 0.6m / s, and the concentration on the net is 0.8wt%; Core-shell structure modified silicone resin emulsion is sprayed between the layers, and the spraying amount is 15% of the mass of each fiber layer.

[0024] Co-curing: hot pressing at 180°C and 6 MPa for 12 minutes.

[0025] Example 2 Raw material formula (by mass): Basalt fiber (diameter 1-3μm:3-5μm=1:2.5, length 4-5mm): 35 parts Core-shell structure modified silicone resin emulsion (solid content 38wt%): 25 parts Nano-intercalated surface treated mica powder: 23 parts Para-aramid fiber (length 2-3mm): 18 parts Polyethylene oxide dispersant: 1.8 parts Aluminum hydroxide flame retardant: 6 parts Preparation process: Preparation of core-shell structure modified silicone resin emulsion: Methylphenyl silicone resin (phenyl content 48%) and epoxypropyltrimethoxysilane were mixed in a molar ratio of 1:0.4, 0.08% platinum catalyst was added, and the mixture was reacted at 87°C under nitrogen protection for 5 hours to generate epoxy-grafted silicone resin.

[0026] The above resin was mixed with ethyl orthosilicate at a ratio of 1:0.4, and diluted hydrochloric acid with a pH value of 4, which was 14% of the resin mass, was added for hydrolysis and condensation for 1 hour. During this period, nano-silica sol was added at a mass ratio of 3:1.2 to form a core-shell structure emulsion.

[0027] Preparation of nano-intercalated surface treated mica powder: The mica powder was immersed in 10% hydrochloric acid solution (mica powder: hydrochloric acid solution = 1:14), ultrasonically treated at 40 kHz for 30 minutes, and then washed with water until neutral.

[0028] The acid-washed mica powder and γ-aminopropyltriethoxysilane were dispersed in 5 times anhydrous ethanol at a mass ratio of 10:1.6 and stirred at 60°C for 2 hours.

[0029] Add nano-silica sol with a mass ratio of 20% of mica powder, stir and react at 88°C for 6 hours, and then dry and crush to a particle size of ≤10μm.

[0030] Preparation of a high-performance, anti-deformation, high-temperature resistant composite insulation paper: Gradient slurry preparation: Upper slurry: 85% basalt fiber with a diameter of 1-3 μm, beaten to Canadian standard freeness of 420 ml CSF; Middle layer slurry: 80% basalt fiber with a diameter of 3-5μm, beaten to Canadian standard freeness of 390mlCSF; Lower slurry: 85% basalt fiber with a diameter of 1-3 μm, beaten to Canadian standard freeness 420 ml CSF.

[0031] Composite molding: The flow rate of the upper slurry is 0.9m / s, and the concentration on the net is 1.2wt%; The flow rate of the middle layer slurry is 0.8m / s, and the concentration on the net is 1.5wt%; The flow rate of the lower layer slurry is 0.9m / s, and the concentration on the net is 1.2wt%; Core-shell structure modified silicone resin emulsion is sprayed between the layers, and the spraying amount is 20% of the fiber mass of each layer.

[0032] Co-curing: hot pressing at 195°C and 7 MPa for 15 minutes.

[0033] Example 3 Raw material formula (by mass): Ceramic fiber (diameter 1-3μm:3-5μm=1:2.2, length 4-5mm): 40 parts Core-shell structure modified silicone resin emulsion (solid content 40wt%): 28 parts Nano-intercalated surface treated mica powder: 24 parts Para-aramid fiber (length 2-3mm): 19 parts Polyethylene oxide dispersant: 1.9 parts Aluminum hydroxide flame retardant: 7 parts Preparation process: Preparation of core-shell structure modified silicone resin emulsion: Methylphenyl silicone resin (phenyl content 42%) and epoxypropyltrimethoxysilane were mixed in a molar ratio of 1:0.38, 0.07% platinum catalyst was added, and the mixture was reacted at 85°C under nitrogen protection for 4.5 hours to generate epoxy-grafted silicone resin.

[0034] The above resin was mixed with ethyl orthosilicate at a ratio of 1:0.35, and diluted hydrochloric acid with a pH of 3.5, which was 13% of the resin mass, was added for hydrolysis and condensation for 1 hour. During this period, nano-silica sol was added at a mass ratio of 3:1.1 to form a core-shell structure emulsion.

[0035] Preparation of nano-intercalated surface treated mica powder: The mica powder was immersed in 10% hydrochloric acid solution (mica powder: hydrochloric acid solution = 1:13), ultrasonically treated at 40 kHz for 30 minutes, and then washed with water until neutral.

[0036] The acid-washed mica powder and γ-aminopropyltriethoxysilane were dispersed in 5 times anhydrous ethanol at a mass ratio of 10:1.3 and stirred at 60°C for 2 hours.

[0037] Add nano-silica sol with a mass ratio of 20% of mica powder, stir and react at 85°C for 5 hours, and then dry and crush to a particle size of ≤10μm.

[0038] Preparation of a high-performance, anti-deformation, high-temperature resistant composite insulation paper: Gradient slurry preparation: Upper slurry: 80% ceramic fiber with a diameter of 1-3 μm, beaten to Canadian standard freeness 400 ml CSF; Middle layer slurry: 75% of ceramic fiber with a diameter of 3-5μm, slurried to Canadian standard freeness of 370mlCSF; Lower slurry: 80% ceramic fiber with a diameter of 1-3 μm, beaten to Canadian standard freeness 400 ml CSF.

[0039] Composite molding: The flow rate of the upper slurry is 0.75m / s, and the concentration on the net is 1.0wt%; The flow rate of the middle layer slurry is 0.65m / s, and the concentration on the net is 1.3wt%; The flow rate of the lower slurry is 0.75m / s, and the concentration on the net is 1.0wt%; Core-shell structure modified silicone resin emulsion is sprayed between the layers, and the spraying amount is 18% of the mass of each fiber layer.

[0040] Co-curing: hot pressing at 190°C and 6.5 MPa for 14 minutes.

[0041] Example 4 Raw material formula (by mass): Basalt fiber (diameter 1-3μm:3-5μm=1:2.3, length 4-5mm): 45 parts Core-shell structure modified silicone resin emulsion (solid content 37wt%): 31 parts Nano-intercalated surface treated mica powder: 25 parts Para-aramid fiber (length 2-3mm): 20 parts Polyethylene oxide dispersant: 2 parts Aluminum hydroxide flame retardant: 8 parts Preparation process: Preparation of core-shell structure modified silicone resin emulsion: Methylphenyl silicone resin (phenyl content 46%) and epoxypropyltrimethoxysilane were mixed in a molar ratio of 1:0.36, 0.065% platinum catalyst was added, and the mixture was reacted at 83°C under nitrogen protection for 4.2 hours to generate epoxy-grafted silicone resin.

[0042] The above resin was mixed with ethyl orthosilicate at a ratio of 1:0.3, and diluted hydrochloric acid with a pH of 3.2 (12.5% by mass of the resin) was added for hydrolysis and condensation for 1 hour. During this period, nano-silica sol was added at a mass ratio of 3:1.05 to form a core-shell structure emulsion.

[0043] Preparation of nano-intercalated surface treated mica powder: The mica powder was immersed in 10% hydrochloric acid solution (mica powder: hydrochloric acid solution = 1:12.5), ultrasonically treated at 40kHz for 30 minutes, and then washed with water until neutral.

[0044] The acid-washed mica powder and γ-aminopropyltriethoxysilane were dispersed in 5 times anhydrous ethanol at a mass ratio of 10:1.2 and stirred at 60°C for 2 hours.

[0045] Add nano-silica sol with a mass ratio of 20% of mica powder, stir and react at 82°C for 4.5 hours, and then dry and crush to a particle size of ≤10 μm.

[0046] Preparation of a high-performance, anti-deformation, high-temperature resistant composite insulation paper: Gradient slurry preparation: Upper slurry: 78% basalt fiber with a diameter of 1-3 μm, beaten to Canadian standard freeness of 410 ml CSF; Middle layer slurry: 3-5μm diameter basalt fiber accounts for 72%, beaten to Canadian standard freeness 360ml CSF; Lower slurry: 78% of basalt fiber with a diameter of 1-3 μm, beaten to Canadian standard freeness 410 ml CSF.

[0047] Composite molding: The flow rate of the upper slurry is 0.8m / s, and the concentration on the net is 1.1wt%; The flow rate of the middle layer slurry is 0.7m / s, and the concentration on the net is 1.4wt%; The flow rate of the lower slurry is 0.8m / s, and the concentration on the net is 1.1wt%; Core-shell structure modified silicone resin emulsion is sprayed between the layers, and the spraying amount is 16% of the fiber mass of each layer.

[0048] Co-curing: hot pressing at 188°C and 6.8 MPa for 13 minutes.

[0049] Example 5 Raw material formula (by mass): Ceramic fiber (diameter 1-3μm:3-5μm=1:2.5, length 4-5mm): 50 parts Core-shell structure modified silicone resin emulsion (solid content 36wt%): 23 parts Nano-intercalated surface treated mica powder: 23.5 parts Para-aramid fiber (length 2-3mm): 17 parts Polyethylene oxide dispersant: 1.6 parts Aluminum hydroxide flame retardant: 5 parts Preparation process: Preparation of core-shell structure modified silicone resin emulsion: Methylphenyl silicone resin (phenyl content 44%) and epoxypropyltrimethoxysilane were mixed in a molar ratio of 1:0.37, 0.075% platinum catalyst was added, and the mixture was reacted at 86°C under nitrogen protection for 4.8 hours to generate epoxy-grafted silicone resin.

[0050] The above resin was mixed with ethyl orthosilicate at a ratio of 1:0.32, and diluted hydrochloric acid with a pH of 3.8 (13.5% by mass of the resin) was added for hydrolysis and condensation for 1 hour. During this period, nano-silica sol was added at a mass ratio of 3:1.15 to form a core-shell structure emulsion.

[0051] Preparation of nano-intercalated surface treated mica powder: The mica powder was immersed in 10% hydrochloric acid solution (mica powder: hydrochloric acid solution = 1:13.5), ultrasonically treated at 40kHz for 30 minutes, and then washed with water until neutral.

[0052] The acid-washed mica powder and γ-aminopropyltriethoxysilane were dispersed in 5 times anhydrous ethanol at a mass ratio of 10:1.5 and stirred at 60°C for 2 hours.

[0053] Add nano-silica sol with a mass ratio of 20% of mica powder, stir and react at 87°C for 5.5 hours, and then dry and crush to a particle size of ≤10 μm.

[0054] Preparation of a high-performance, anti-deformation, high-temperature resistant composite insulation paper: Gradient slurry preparation: Upper slurry: 82% ceramic fiber with a diameter of 1-3 μm, beaten to Canadian standard freeness 390 ml CSF; Middle layer slurry: 78% of ceramic fiber with a diameter of 3-5μm, beaten to Canadian standard freeness of 380mlCSF; Lower slurry: 82% of ceramic fiber has a diameter of 1-3 μm and is slurried to a Canadian standard freeness of 390 ml CSF.

[0055] Composite molding: The flow rate of the upper slurry is 0.85m / s, and the concentration on the net is 1.15wt%; The flow rate of the middle layer slurry is 0.75m / s, and the concentration on the net is 1.45wt%; The flow rate of the lower slurry is 0.85m / s, and the concentration on the net is 1.15wt%; Core-shell structure modified silicone resin emulsion is sprayed between the layers, and the spraying amount is 19% of the fiber mass of each layer.

[0056] Co-curing: hot pressing at 185°C and 6.2 MPa for 13 minutes.

[0057] Comparative Example 1 Raw material formula (by mass): Basalt fiber (single diameter 5μm, length 4-5mm): 30 parts Unmodified silicone resin emulsion (solid content 35wt%): 20 parts Unintercalated mica powder: 22 parts Para-aramid fiber (length 2-3mm): 16 parts Polyethylene oxide dispersant: 1.5 parts Aluminum hydroxide flame retardant: 4 parts Preparation process: Preparation of resin emulsion: Methylphenyl silicone resin and epoxypropyltrimethoxysilane were mixed in a molar ratio of 1:0.35, 0.06% platinum catalyst was added, and the mixture was reacted at 82°C under nitrogen protection for 4 hours without sol-gel modification.

[0058] Mica powder treatment: only ultrasonic treatment with 10% hydrochloric acid for 30 minutes, without silane coupling agent treatment.

[0059] Preparation of a high-performance, deformation-resistant, high-temperature-resistant composite insulating paper: using a single fiber slurry, without spraying resin emulsion between layers, and hot pressing at 180°C and 6MPa for 12 minutes.

[0060] Comparative Example 2 Raw material formula (by mass): Basalt fiber (diameter 1-3μm:3-5μm=1:1, non-gradient distribution, length 4-5mm): 35 parts Silicone resin emulsion (no core-shell structure, solid content 38wt%): 25 parts Silane coupling agent single-treatment mica powder: 23 parts Para-aramid fiber (length 2-3mm): 18 parts Polyethylene oxide dispersant: 1.8 parts Aluminum hydroxide flame retardant: 6 parts Preparation process: Preparation of resin emulsion: The step of adding nano-silica sol was omitted, and only epoxy group grafting was performed, without forming a core-shell structure.

[0061] Mica powder treatment: After pickling, it was only treated with γ-aminopropyltriethoxysilane without inserting nano-silica.

[0062] Preparation of a high-performance, deformation-resistant, high-temperature-resistant composite insulating paper: the slurry is not layered, a single fiber is mixed, ordinary resin emulsion is sprayed between layers, and hot pressed at 185°C and 6.5MPa for 13 minutes.

[0063] Performance Testing High temperature resistance test The examples and comparative samples of the same specifications were tested with reference to GB / T19289-2018: Table 1 It can be seen from Table 1 that the composite paper prepared in the present invention has excellent high temperature resistance.

[0064] Anti-deformation performance test The examples and comparative samples of the same specifications were tested with reference to GB / T1036-2008: Table 2 It can be seen from Table 2 that the composite paper prepared in the present invention has excellent anti-deformation ability.

[0065] Insulation performance test Conduct insulation performance tests on the examples and comparative samples of the same specifications; Table 3 The composite paper prepared by the invention has excellent insulation performance.

[0066] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A high-performance, anti-deformation, high-temperature resistant composite insulating paper, characterized in that: It is composed of the following ingredients in parts by mass: 30-50 parts of inorganic fiber, wherein the inorganic fiber is basalt fiber or ceramic fiber, with a length of 4-5 mm; 20-31 parts of core-shell structure modified silicone resin emulsion; 22-25 parts of nano-intercalated surface-treated mica powder, wherein the surface-treated mica powder is double-treated with acid washing and silane coupling agent, and nano-silica particles are inserted between the layers; 16-20 parts of aramid fiber, wherein the aramid fiber is para-aramid and has a length of 2-3 mm; Auxiliary additives: dispersant polyethylene oxide 1.5-2 parts, flame retardant aluminum hydroxide 4-8 parts.

2. The high-performance, anti-deformation, high-temperature-resistant composite insulating paper according to claim 1, characterized in that: The inorganic fibers include: Inorganic fibers with a diameter of 1-3 μm and inorganic fibers with a diameter of 3-5 μm are mixed in a mass ratio of 1:2-2.

5.

3. The high-performance, anti-deformation, high-temperature-resistant composite insulating paper according to claim 1, characterized in that: The preparation method of the core-shell structure modified silicone resin emulsion comprises: Mixing methylphenyl silicone resin and glycidyltrimethoxysilane at a molar ratio of 1:0.35-0.4 under nitrogen protection, adding 0.06-0.08% of a platinum catalyst by weight of the mixture, and reacting at 82-87° C. for 4-5 hours to produce an epoxy-grafted silicone resin; The epoxy-grafted silicone resin and ethyl orthosilicate are mixed at a ratio of 1:0.28-0.4, and then diluted hydrochloric acid with a pH of 3-4, which is 12-14% by weight of the epoxy-grafted silicone resin, is added for hydrolysis and condensation for 1 hour to form an organic-inorganic hybrid network structure; During the hydrolysis and condensation process, nano-silica sol is added in a mass ratio of 3:1-1.2 and mixed evenly to obtain; The emulsion solid content is 35-40wt%.

4. The high-performance, anti-deformation, high-temperature-resistant composite insulating paper according to claim 1, characterized in that: The preparation method of the nano-intercalation surface-treated mica powder comprises: Immerse the mica powder in 10% hydrochloric acid solution and ultrasonicate for 30 minutes, then wash with water until neutral; Mix the acid-washed mica powder with γ-aminopropyltriethoxysilane in a mass ratio of 10:1-1.6, disperse in anhydrous ethanol 5 times the total mass of the mixture, and stir at 60°C for 2 hours; Add nano-silica sol with a mass ratio of 20% of mica powder, stir and react at 80-88°C for 4-6 hours to allow nano-silica to be inserted between the mica powder layers, and then grind to a particle size of ≤10μm after drying.

5. The high-performance, anti-deformation, high-temperature-resistant composite insulating paper according to claim 4, characterized in that: The mixing ratio of the mica powder to the hydrochloric acid solution is 1:12-14; The frequency of the ultrasonic treatment was 40 kHz.

6. The high-performance, anti-deformation, high-temperature-resistant composite insulating paper according to claim 1, characterized in that: The method for preparing the high-performance, deformation-resistant, high-temperature-resistant composite insulating paper comprises: Gradient slurry preparation: Gradient-distributed inorganic fibers, surface-treated aramid fibers, and nano-intercalated surface-treated mica powder are evenly dispersed in water to form a three-layer graded slurry system; Composite molding: Using a multi-layer inclined mesh composite papermaking machine, control the following: the upper layer slurry flow rate is 0.6-0.9m / s, the net concentration is 0.8-1.2wt%; the middle layer slurry flow rate is 0.5-0.8m / s, the net concentration is 1.0-1.5wt%; the lower layer slurry flow rate is 0.6-0.9m / s, the net concentration is 0.8-1.2wt%; the core-shell structure modified silicone resin emulsion is sprayed between the layers, and the spraying amount is 15-20% of the fiber mass of each layer; Synergistic curing: hot pressing at 180-195°C and pressure 6-7MPa for 12-15 minutes to form a synergistically reinforced network structure between the modified silicone resin and the nano-intercalated mica powder.

7. The high-performance, anti-deformation, high-temperature-resistant composite insulating paper according to claim 6, characterized in that: The three-layer graded pulp system comprises: an upper pulp layer comprising inorganic fibers with a diameter of 1-3 μm accounting for 70-85% of the total mass of the fibers in this layer, and being pulped to a Canadian standard freeness of 380-420 ml CSF; a middle pulp layer comprising inorganic fibers with a diameter of 3-5 μm accounting for 65-80% of the total mass of the fibers in this layer, and being pulped to a Canadian standard freeness of 350-390 ml CSF; and a lower pulp layer comprising inorganic fibers with a diameter of 1-3 μm accounting for 70-85% of the total mass of the fibers in this layer, and being pulped to a Canadian standard freeness of 380-420 ml CSF.

8. The high-performance, anti-deformation, high-temperature-resistant composite insulating paper according to claim 1, characterized in that: The high-performance, deformation-resistant, and high-temperature-resistant composite insulating paper has an interlayer dielectric constant gradient structure, wherein the surface layer dielectric constant is 3.0-3.5, and the middle layer dielectric constant is 4.0-4.

5.

9. The high-performance, anti-deformation, high-temperature-resistant composite insulating paper according to claim 1, characterized in that: The volume resistivity of the high-performance, anti-deformation, high-temperature resistant composite insulating paper at 200°C is ≥1×10 12 Ω·cm, breakdown field strength ≥30kV / mm.

10. The high-performance, anti-deformation, high-temperature-resistant composite insulating paper according to claim 1, characterized in that: The high-performance, deformation-resistant, high-temperature-resistant composite insulation paper has a thermal expansion coefficient of ≤15 ppm / °C and a thermal weight loss of ≤5% at 400°C.

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