A type of high-pressure explosion-proof mica tape

Abstract

This invention discloses a high-pressure explosion-proof mica tape, belonging to the technical field of mica tape. It comprises a first protective layer, a first reinforcing layer, a first adhesive layer, a main insulating layer, a second adhesive layer, a second reinforcing layer, and a second protective layer, stacked sequentially. The main insulating layer is a reinforced mica paper formed by wet-processing large-flake mica paper and aramid fibers, wherein the mica flakes have a diameter-to-thickness ratio greater than 80 and are oriented in the paper surface direction. The first and second reinforcing layers are both polyimide films with a thickness of 0.025 mm to 0.05 mm. The first and second protective layers are both nano-silica modified silicone resin coatings. This invention, by setting a seven-layer symmetrical structure including the first protective layer, first reinforcing layer, first adhesive layer, main insulating layer, second adhesive layer, second reinforcing layer, and second protective layer, significantly improves the comprehensive mechanical strength and protective performance of the mica tape.

Description

Technical Field

[0001] This invention relates to the field of mica tape technology, and more specifically, to a high-pressure explosion-proof mica tape. Background Technology

[0002] Mica tape is a strip-shaped insulating material made from mica paper as the base material, supplemented with reinforcing materials and adhesives. Due to its excellent electrical insulation properties, high-temperature resistance, and corona resistance, it is widely used in the insulation structures of high-voltage motors, transformers, cables, and other power equipment. As the power industry develops towards high voltage and large capacity, more stringent requirements are being placed on the performance of insulating materials. An ideal mica tape not only needs extremely high breakdown voltage and volume resistivity to ensure electrical safety, but also good thermal conductivity to dissipate the heat generated by generator operation, as well as excellent mechanical strength and interlayer bonding to withstand tension, bending, and friction during wrapping, winding, and other processes, and to resist thermal stress and environmental humid heat corrosion during long-term operation.

[0003] However, existing mica tapes generally suffer from performance imbalances. Traditional mica tapes often employ a simple three-layer structure (mica paper layer plus a single-sided reinforcing layer). Their main insulating layer typically uses ordinary mica paper with a small diameter-to-thickness ratio and disordered arrangement of mica flakes, resulting in numerous microscopic defects within the insulating layer. This makes it difficult to meet the high breakdown field strength requirements of high-voltage applications. Furthermore, the significant difference in thermal expansion coefficients between the single reinforcing layer and the mica paper easily generates interfacial stress during temperature cycling, leading to interlayer cracking or delamination. In addition, traditional adhesive layers have poor thermal conductivity, causing heat to accumulate within the insulating layer and accelerating material aging. Moreover, the surface abrasion resistance of the mica tape is insufficient, making it prone to scratches or fuzzing during wrapping, affecting the integrity of the insulation.

[0004] Based on this, the present invention designs a high-pressure explosion-proof mica tape to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a high-pressure explosion-proof mica tape to solve the problems mentioned in the background art.

[0006] A high-voltage explosion-proof mica tape includes a first protective layer, a first reinforcing layer, a first adhesive layer, a main insulating layer, a second adhesive layer, a second reinforcing layer, and a second protective layer, which are stacked sequentially.

[0007] The main insulating layer is a reinforced mica paper formed by wet papermaking of large-flake mica paper and aramid fiber, wherein the diameter-to-thickness ratio of the mica flakes is greater than 80, and the mica flakes are oriented in the direction of the paper surface.

[0008] Both the first reinforcing layer and the second reinforcing layer are polyimide films with a thickness of 0.025 mm to 0.05 mm;

[0009] Both the first and second protective layers are nano-silica modified organosilicon resin coatings, used to improve the wear resistance, moisture resistance and reduce the surface friction coefficient of the mica tape;

[0010] The first and second adhesive layers are high-temperature resistant epoxy resin adhesives, and spherical silica micropowder is dispersed therein to adjust the thermal expansion coefficient of the adhesive so that it is between the main insulating layer and the first and second reinforcing layers.

[0011] Preferably, the mica flake content in the main insulating layer is 85%-92% by weight, the aramid fiber content is 8%-15% by weight, and the thickness of the main insulating layer is 0.10mm to 0.15mm.

[0012] Preferably, 5%-10% by weight of nano-boron nitride powder is added to the first and second adhesive layers to improve the thermal conductivity of the adhesive layers and form an internal thermally conductive network.

[0013] Preferably, at least one outer surface of the first reinforcing layer and the second reinforcing layer is provided with a corona treatment layer, the surface tension value of which is not less than 52 dyne / cm, and the first protective layer and the second protective layer are selectively configured single-layer structures, and the nano-silica modified organosilicon resin coating is provided on the outermost layer only when the mica tape is used as the outer wrapping layer.

[0014] Preferably, the spherical silica micropowder in the first and second adhesive layers has a surface treated with a coupling agent and a bimodal particle size distribution, that is, it contains small particles with a diameter of 0.5-1 μm and large particles with a diameter of 3-5 μm, and the mass ratio of the small and large particles is 1:2 to 1:3.

[0015] Preferably, the upper and lower surfaces of the main insulating layer are roughened by plasma treatment to form a roughened interface with a surface roughness Ra of 0.2-0.5 μm. The first adhesive layer and the second adhesive layer partially penetrate into the roughened interface to form an anchoring structure.

[0016] Preferably, after corona treatment, the polyimide film surfaces of the first and second reinforcing layers are further coated with a coupling agent undercoating layer. The coupling agent undercoating layer is a composite sol of aminosilane coupling agent and nano-alumina, with a thickness of 50-200 nm. The coupling agent undercoating layer is used to anchor the active groups generated by the corona treatment and to chemically crosslink with the epoxy groups in the first and second adhesive layers.

[0017] Preferably, the first adhesive layer and the second adhesive layer further contain 3%-8% by mass of titanate-modified boron nitride nanotubes, wherein the boron nitride nanotubes have a diameter of 5-15 nm and a length of 1-5 μm, and the boron nitride nanotubes are oriented along the thickness direction of the mica strip to form directional heat conduction channels.

[0018] Preferably, the main insulating layer contains hydrophobically modified nano-silica aerogel with a mass fraction of 1%-3%. The hydrophobically modified nano-silica aerogel has a pore size of less than 50 nm and a porosity of more than 90%, which is used to adsorb and fix the trace amount of moisture introduced by the aramid fiber, while buffering the thermal stress between the layers.

[0019] Compared with the prior art, the advantages of this invention are:

[0020] 1. This invention significantly improves the overall mechanical strength and protective performance of mica tape by setting a seven-layer symmetrical structure including a first protective layer, a first reinforcing layer, a first adhesive layer, a main insulating layer, a second adhesive layer, a second reinforcing layer, and a second protective layer. Specifically, the synergistic effect of the upper and lower double-layer polyimide film reinforcing layers (thickness 0.025mm to 0.05mm) and the double-layer nano-silica modified silicone resin protective layer not only greatly improves the tensile and tear strength of the mica tape, but also significantly enhances the product's wear resistance and moisture resistance and reduces the surface friction coefficient through the outer protective coating. This makes it more resistant to mechanical stress and environmental erosion during high-voltage wrapping, extending the service life of the insulation system.

[0021] 2. This invention, through the special limitation of the main insulating layer material, uses large-scale mica flakes with a diameter-to-thickness ratio greater than 80 and aramid fibers to form reinforced mica paper through wet papermaking, and achieves the directional arrangement of mica flakes, which significantly improves the density and electrical strength of the insulating layer. The highly directional arrangement of large-scale mica flakes (diameter-to-thickness ratio > 80) in the paper surface direction forms a more effective insulating barrier, significantly increasing the tortuosity of the breakdown path, thereby improving the breakdown voltage; at the same time, the addition of aramid fibers enhances the mechanical toughness and tensile strength of the mica paper, solving the problem of high brittleness and easy breakage of traditional mica paper, and ensuring the structural integrity of the main insulating layer under high pressure, high temperature and mechanical stress.

[0022] 3. This invention disperses spherical silica micropowder in a high-temperature resistant epoxy resin adhesive, ensuring its coefficient of thermal expansion falls between that of the main insulating layer and the polyimide reinforcing layer. This effectively alleviates thermal stress in multilayer structures under temperature changes. This design allows the adhesive layer to act as a buffer layer for thermal expansion, preventing interface peeling, cracking, or curling caused by mismatched coefficients of thermal expansion between the layers. Furthermore, adding 5%-10% nano-boron nitride powder to the first and second adhesive layers constructs an internal thermally conductive network, significantly improving the thermal conductivity of the adhesive layer. This allows heat generated within the mica tape to be quickly dissipated, preventing localized overheating and enhancing the product's operational reliability under high-pressure conditions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a high-pressure explosion-proof mica tape proposed in this invention. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0025] Example 1

[0026] A high-voltage explosion-proof mica tape includes a first protective layer, a first reinforcing layer, a first adhesive layer, a main insulating layer, a second adhesive layer, a second reinforcing layer, and a second protective layer, which are stacked sequentially.

[0027] The main insulation layer is a reinforced mica paper formed by wet papermaking of large-flake mica paper and aramid fiber. The mica flakes have a diameter-to-thickness ratio of 85 and a content of 88% by weight, while the aramid fiber content is 12%, and the thickness is 0.12 mm. The mica flakes are oriented in the paper surface direction with an orientation degree of 92.5%.

[0028] Both the first and second reinforcing layers are polyimide films with a thickness of 0.035 mm. Their outer surfaces are corona-treated with a surface tension of 54 dyne / cm, and are further coated with an aminosilane coupling agent and nano-alumina composite sol-gel base coating with a thickness of 100 nm.

[0029] Both the first and second protective layers are nano-silica modified organosilicon resin coatings, used to improve the wear resistance, moisture resistance and reduce the surface friction coefficient of the mica tape.

[0030] The first and second adhesive layers use a high-temperature resistant epoxy resin adhesive, in which spherical silica micropowder treated with a coupling agent is dispersed. The particle size has a bimodal distribution (0.5-1μm and 3-5μm, mass ratio 1:2.5) to adjust the thermal expansion coefficient of the adhesive, making it between that of the main insulating layer and the reinforcing layer. Simultaneously, 8% by weight of nano-boron nitride powder and 5% by weight of titanate-modified boron nitride nanotubes are added. The boron nitride nanotubes have a diameter of 10nm and a length of 3μm, and are oriented along the thickness direction of the mica band, forming directional heat-conducting channels.

[0031] The upper and lower surfaces of the main insulating layer are roughened through plasma treatment to form a surface roughness Ra of 0.3 μm. The first and second adhesive layers partially penetrate into this roughened interface to form an anchoring structure. In addition, the main insulating layer also contains 2% by mass of hydrophobic modified nano-silica aerogel with a pore size of less than 50 nm and a porosity of more than 90%, which is used to adsorb and fix the trace amounts of moisture introduced by the aramid fibers, while buffering the thermal stress between the layers.

[0032] Example 2

[0033] The difference between this embodiment and Embodiment 1 is that:

[0034] The main insulating layer contains 90% mica flakes and 10% aramid fiber, with a thickness of 0.10 mm; the first and second reinforcing layers have a thickness of 0.025 mm; the first and second adhesive layers contain 5% boron nitride powder, 3% boron nitride nanotubes, and a 1:2 ratio of spherical silica microparticles by size; and the aerogel content is 1%.

[0035] Example 3

[0036] The difference between this embodiment and Embodiment 1 is that:

[0037] The main insulating layer contains 85% mica flakes and 15% aramid fiber, with a thickness of 0.15 mm; the first and second reinforcing layers have a thickness of 0.05 mm; the first and second adhesive layers contain 10% boron nitride powder, 8% boron nitride nanotubes, and a 1:3 ratio of spherical silica microparticles by size; and the aerogel content is 3%.

[0038] Comparative Example 1

[0039] This comparative example uses a traditional three-layer mica tape structure, including a mica paper layer, a single-layer polyimide film reinforcing layer, and a single-sided epoxy resin adhesive layer, without any modified design for a protective layer, double reinforcing layer, or adhesive layer.

[0040] Specifically: the mica paper is ordinary mica paper with a mica flake aspect ratio of 60, no aramid fiber added, and a thickness of 0.12 mm; the reinforcing layer is a single-layer polyimide film with a thickness of 0.035 mm; the adhesive layer is ordinary epoxy resin adhesive without spherical silica micro powder, boron nitride powder, or boron nitride nanotubes added; the reinforcing layer has not undergone corona treatment or primer coating treatment; there is no aerogel dispersion system; and the surface of the mica paper has not undergone roughening treatment.

[0041] Comparative Example 2

[0042] This comparative example has the same structure as Example 1, but spherical silica micropowder and boron nitride nanotubes were not added to the first and second adhesive layers, and the main insulating layer was not subjected to plasma roughening treatment. The reinforcing layer was not coated with a coupling agent undercoating.

[0043] Specifically: the first and second adhesive layers are pure high-temperature resistant epoxy resin adhesives; the upper and lower surfaces of the main insulating layer are untreated; the reinforcing layer is only corona treated and is not coated with a coupling agent primer; the rest of the structure is the same as in Example 1.

[0044] Performance Testing and Comparison

[0045] I. Sample Preparation

[0046] Mica tape samples prepared in Examples 1-3 and Comparative Examples 1-2 were selected. All samples were equilibrated for 24 hours at a temperature of 23℃±2℃ and a relative humidity of 50%±5% before testing. Five parallel samples were tested for each type of sample, and the average value was taken as the final result.

[0047] II. Test Items and Methods

[0048] 1. Breakdown voltage test

[0049] Test standard: GB / T1408.1-2016 "Insulating materials - Electrical strength test methods - Part 1: Tests at power frequency"

[0050] Testing instrument: High voltage breakdown tester (Model: HT-100kV, accuracy: ±2%)

[0051] Test steps:

[0052] Cut the mica tape sample into 100mm×100mm squares;

[0053] An unequal diameter electrode system is used, with the upper electrode diameter being 25mm and the lower electrode diameter being 75mm, and the edges are chamfered;

[0054] The sample was placed between the electrodes and immersed in transformer oil to prevent surface flashover.

[0055] A voltage is applied at a constant rate of 2 kV / s until the sample breaks down.

[0056] Record the breakdown voltage value (kV) and calculate the electrical strength using the formula:

[0057] Electrical strength (kV / mm) = Breakdown voltage (kV) / Sample thickness (mm)

[0058] Test conditions: Temperature 23℃±2℃, power frequency 50Hz

[0059] 2. Thermal conductivity test

[0060] Test standard: GB / T42919.1-2023 "Determination of thermal conductivity and thermal diffusivity of plastics - Part 1: Flash test"

[0061] Test instrument: Laser thermal conductivity meter (Model: NETZSCHLFA467, accuracy: ±3%)

[0062] Test steps:

[0063] Cut the mica tape sample into circular pieces with a diameter of 12.7 mm;

[0064] The sample was coated with a thin layer of graphite on both sides to enhance laser absorption and infrared emission;

[0065] Place the sample in the sample holder and test it under a constant temperature of 25℃.

[0066] A laser pulse irradiates the lower surface of the sample, while an infrared detector monitors the temperature response of the upper surface.

[0067] The thermal diffusivity is calculated by analyzing the temperature-time curve using software. ;

[0068] Based on known specific heat capacity and density Calculate the thermal conductivity : .

[0069] 3. Thermal expansion coefficient test

[0070] Test standard: GB / T1036-2022 "Determination of the linear thermal expansion coefficient of plastics - Thermomechanical analysis method"

[0071] Test instrument: Thermomechanical analyzer (Model: TAInstrumentsQ400, Accuracy: ±2%)

[0072] Test steps:

[0073] Cut the mica tape sample into strips of 5mm × 20mm;

[0074] The sample was placed between quartz clamps and a small compressive force of 0.05 N was applied.

[0075] Set the temperature program: increase the temperature from 30℃ to 200℃ at a rate of 5℃ / min;

[0076] Record the curve of sample length changing with temperature;

[0077] Calculate the average coefficient of linear expansion in the temperature range of 30-200℃:

[0078]

[0079] 4. Interlayer peel strength test

[0080] Test standard: GB / T2792-2014 "Test method for peel strength of adhesive tapes"

[0081] Testing instrument: Universal testing machine (Model: Instron3343, accuracy: ±0.5%)

[0082] Test steps:

[0083] Cut the mica tape sample into strips of 25mm × 200mm;

[0084] Manually pre-peel one end by about 30mm, and clamp the separated ends in the upper and lower clamps respectively;

[0085] The stretching speed is set to 300 mm / min, and the peeling angle is set to 180°.

[0086] Peel continuously for at least 100 mm in length and record the peel force curve;

[0087] Calculate the average peel force and divide it by the sample width to obtain the peel strength (N / cm).

[0088] Test conditions: Temperature 23℃±2℃, relative humidity 50%±5%

[0089] 5. Damp heat aging resistance test

[0090] Test Standard: GB / T2423.3-2016 Environmental Testing - Part 2: Test Methods - Test Cab: Constant Damp Heat Test

[0091] Testing instrument: Constant temperature and humidity test chamber (Model: ESPECARS-1100, accuracy: ±0.5℃ / ±3%RH)

[0092] Test steps:

[0093] Cut the mica tape sample into 100mm×100mm squares;

[0094] Test the initial breakdown voltage value (according to GB / T1408.1-2016).

[0095] The sample was placed in a constant temperature and humidity chamber, with the temperature set at 85℃ and the relative humidity at 85%.

[0096] The aging time was 1000 hours, and samples were taken every 200 hours to observe changes in appearance.

[0097] After aging, the samples were allowed to recover for 24 hours under standard conditions;

[0098] Test the breakdown voltage value again;

[0099] Calculate the breakdown voltage retention rate:

[0100] Retention rate (%) = breakdown voltage after aging / initial breakdown voltage × 100%.

[0101] 6. Volume resistivity test

[0102] Test standard: GB / T31838.2-2019 "Dielectric and resistive properties of solid insulating materials - Part 2: Volume resistivity and volume resistivity"

[0103] Test instrument: High resistance meter (Model: Keithley 6517B, accuracy: ±1%)

[0104] Test steps:

[0105] Cut the mica tape sample into 100mm×100mm squares;

[0106] A three-electrode system is used to protect the electrode and eliminate surface leakage current;

[0107] After applying a 500V DC voltage and charging for 60 seconds, read the resistance value R.

[0108] Measure the sample thickness d and calculate the volume resistivity. : (Ω·m) = R × (A / d);

[0109] Where A is the effective area of ​​the main electrode (m²);

[0110] Test conditions: Temperature 23℃±2℃, relative humidity 50%±5%.

[0111] 7. Dynamic Mechanics Analysis (DMA)

[0112] Test standard: GB / T40396-2021 "Determination of Dynamic Mechanical Properties of Polymer-Based Composite Materials - Vibration Beam Method"

[0113] Testing instrument: Dynamic mechanical analyzer (Model: TAInstrumentsQ800, accuracy: ±2%)

[0114] Test steps:

[0115] Cut the mica tape sample into strips of 10mm × 35mm;

[0116] A tension clamp was used, with an amplitude of 15μm and a frequency of 1Hz.

[0117] The temperature was increased from 30℃ to 250℃ at a rate of 3℃ / min.

[0118] Record the changes in energy storage modulus E', loss modulus E'', and loss factor tanδ with temperature;

[0119] Analyze the glass transition temperature (Tg) and interfacial bonding.

[0120] 8. Observation of the scanning electron microscope (SEM) interface

[0121] Test standard: GB / T16594-2008 "Scanning electron microscopy measurement methods for micrometer-scale lengths"

[0122] Testing instrument: Field emission scanning electron microscope (model: Hitachi SU8010, resolution: 1.0 nm)

[0123] Test steps:

[0124] The mica ribbon sample was fractured in liquid nitrogen to obtain a fresh fracture surface;

[0125] Gold plating treatment on the cross-section (thickness approximately 10nm);

[0126] The cross-sectional morphology was observed under a 5kV accelerating voltage.

[0127] The key areas of focus are the interlayer interface bonding, the penetration depth of the adhesive layer, and the dispersion state of the filler.

[0128] 9. X-ray diffraction (XRD) analysis

[0129] Test standard: GB / T30904-2014 "X-ray Diffraction Method for Crystal Structure Analysis of Inorganic Chemical Products"

[0130] Testing instrument: X-ray diffractometer (model: Bruker D8 Advance, CuKα radiation)

[0131] Test steps:

[0132] Lay the mica tape sample flat on the sample holder;

[0133] Scan range Step size 0.02°, scan speed 4° / min;

[0134] Analyze the degree of orientation of mica flakes and calculate the degree of orientation by the intensity ratio of characteristic peaks:

[0135] Orientation degree (%) = ;

[0136] in The diffraction intensity is in the parallel direction. The diffraction intensity is in the vertical direction.

[0137] III. Test Results

[0138] Breakdown voltage (kV / mm) 32.5±1.2 30.8±1.1 31.6±1.3 22.4±1.5 26.3±1.4 Thermal conductivity (W / m·K) 0.85±0.03 0.78±0.02 0.82±0.03 0.32±0.02 0.45±0.03 Coefficient of thermal expansion (ppm / K) 18.2±0.8 19.1±0.9 18.7±0.7 28.5±1.2 24.3±1.1 Interlayer peel strength (N / cm) 4.8±0.3 4.5±0.2 4.6±0.3 2.1±0.2 3.2±0.3 Breakdown retention rate after aging (%) 94.5±2.1 92.3±2.3 93.1±2.0 68.7±3.5 79.5±3.2 <![CDATA[Volume resistivity (×10¹ 4 Ω·m)]]> 8.2±0.4 7.9±0.3 8.1±0.4 3.5±0.3 5.2±0.4 Glass transition temperature Tg (°C) 185±3 182±4 184±3 156±5 168±4 Mica orientation degree (%) 92.5 91.8 92.1 68.3 76.5

[0139] IV. Results Analysis

[0140] Based on the above test results, the high-voltage explosion-proof mica tape prepared in this embodiment of the invention significantly outperforms the comparative example in all key performance indicators. In terms of electrical performance, the breakdown voltage of the sample in this embodiment exceeds 30 kV / mm, and the volume resistivity exceeds [missing value]. Compared to Comparative Example 1, the performance was improved by 45% and 120% respectively. This is attributed to the highly oriented arrangement (orientation degree >92%) of large flake mica (aspect ratio >80) forming a dense insulating barrier, the aramid fiber reinforcement reducing microscopic defects, and the silica aerogel adsorbing trace amounts of moisture to prevent partial discharge. Regarding thermal conductivity and thermal matching performance, the thermal conductivity of the examples reached 0.78-0.85 W / m·K, more than 2.5 times that of Comparative Example 1, and the coefficient of thermal expansion (18-19 ppm / K) was closer to that of conductor materials. This was due to the highly efficient thermally conductive network constructed by boron nitride powder and oriented boron nitride nanotubes, and the precise control of the thermal expansion behavior of the adhesive layer by spherical silica micropowder.

[0141] Regarding interfacial bonding and durability, the interlayer peel strength of the example samples reached 4.5-4.8 N / cm, more than twice that of Comparative Example 1. After 1000 hours of damp heat aging, the breakdown voltage retention rate was >92%, significantly higher than the 68.7% of Comparative Example 1. This is mainly due to the roughened interface formed by plasma treatment and the anchoring structure of the adhesive layer, the chemical cross-linking achieved by corona treatment combined with the coupling agent undercoating, and the excellent moisture barrier provided by the nano-silica modified organosilicon protective layer. In addition, DMA testing showed that the glass transition temperature of the examples reached 182-185℃, nearly 30℃ higher than that of Comparative Example 1, indicating that the cross-linking network of boron nitride nanotubes and coupling agent significantly improved the thermomechanical stability of the material.

[0142] In summary, this invention, through multi-layered structural collaborative design, functional filler compounding, and interface engineering optimization, successfully solves key technical problems such as poor thermal conductivity, poor thermal matching, and weak interface bonding of traditional mica tape. Its comprehensive performance meets the stringent requirements for insulating materials in high-voltage explosion-proof applications, demonstrating significant technological progress.

[0143] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-pressure explosion-proof mica tape, characterized in that, It includes a first protective layer, a first reinforcing layer, a first adhesive layer, a main insulating layer, a second adhesive layer, a second reinforcing layer, and a second protective layer, which are stacked in sequence. The main insulating layer is a reinforced mica paper formed by wet papermaking of large-flake mica paper and aramid fiber, wherein the diameter-to-thickness ratio of the mica flakes is greater than 80, and the mica flakes are oriented in the direction of the paper surface. Both the first reinforcing layer and the second reinforcing layer are polyimide films with a thickness of 0.025 mm to 0.05 mm; Both the first and second protective layers are nano-silica modified organosilicon resin coatings, used to improve the wear resistance, moisture resistance and reduce the surface friction coefficient of the mica tape; The first and second adhesive layers are high-temperature resistant epoxy resin adhesives, and spherical silica micropowder is dispersed therein to adjust the thermal expansion coefficient of the adhesive so that it is between the main insulating layer and the first and second reinforcing layers.

2. The high-pressure explosion-proof mica tape according to claim 1, characterized in that, The main insulating layer contains 85%-92% mica flakes by weight and 8%-15% aramid fiber by weight, and the thickness of the main insulating layer is 0.10mm to 0.15mm.

3. The high-pressure explosion-proof mica tape according to claim 2, characterized in that, The first and second adhesive layers also contain 5%-10% boron nitride nanoparticles by weight to improve the thermal conductivity of the adhesive layers and form an internal thermally conductive network.

4. The high-pressure explosion-proof mica tape according to claim 1, characterized in that, At least one outer surface of the first reinforcing layer and the second reinforcing layer is provided with a corona treatment layer, the surface tension value of which is not less than 52 dyne / cm. The first protective layer and the second protective layer are selectively configured single-layer structures. The nano-silica modified organosilicon resin coating is provided on the outermost layer only when the mica tape is used as the outer wrapping layer.

5. A high-pressure explosion-proof mica tape according to claim 4, characterized in that, The spherical silica micropowder in the first and second adhesive layers has a surface treated with a coupling agent and a bimodal particle size distribution, that is, it contains small particles with a diameter of 0.5-1μm and large particles with a diameter of 3-5μm, and the mass ratio of the large and small particles is 1:2 to 1:

3.

6. A high-pressure explosion-proof mica tape according to claim 5, characterized in that, The upper and lower surfaces of the main insulating layer are roughened by plasma treatment to form a roughened interface with a surface roughness Ra of 0.2-0.5 μm. The first adhesive layer and the second adhesive layer partially penetrate into the roughened interface to form an anchoring structure.

7. A high-pressure explosion-proof mica tape according to claim 4, characterized in that, After corona treatment, the polyimide film surfaces of the first and second reinforcing layers are further coated with a coupling agent undercoating layer. The coupling agent undercoating layer is a composite sol of aminosilane coupling agent and nano-alumina, with a thickness of 50-200 nm. The coupling agent undercoating layer is used to anchor the active groups generated by the corona treatment and to chemically crosslink with the epoxy groups in the first and second adhesive layers.

8. A high-pressure explosion-proof mica tape according to claim 7, characterized in that, The first and second adhesive layers also contain 3%-8% by mass of titanate-modified boron nitride nanotubes. The boron nitride nanotubes have a diameter of 5-15 nm and a length of 1-5 μm. The boron nitride nanotubes are oriented along the thickness direction of the mica strip to form directional heat conduction channels.

9. A high-pressure explosion-proof mica tape according to claim 8, characterized in that, The main insulating layer contains hydrophobically modified nano-silica aerogel with a mass fraction of 1%-3%. The pore size of the hydrophobically modified nano-silica aerogel is less than 50 nm and the porosity is greater than 90%. It is used to adsorb and fix the trace amount of moisture introduced by the aramid fiber, while buffering the thermal stress between the layers.

Images