Preparation method of meta-aramid / nano-TiO2 composite insulating paper with high insulation strength

Abstract

The present invention discloses a preparation method of a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper, belonging to the technical field of electrical engineering materials, which comprises the following steps: S1: dopamine pretreatment of nano-TiO2; S2: coupling agent treatment of nano-TiO2; S3: preparation of a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper; the present invention improves the binding ability between nano-fillers and aramid paper through the synergistic effect of dopamine coating and silane coupling agent, and effectively improves the breakdown voltage of the composite insulating paper by reducing the volume conductivity and increasing the depth of the carrier trap of the material; at the same time, starting from the existing processes of papermaking industry production, this process is improved, with simple operation, convenient implementation, low cost, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrical engineering materials, and particularly relates to a preparation method of a meta-aramid / nano-TiO2 composite insulating paper with high insulation strength. Background Technique

[0002] Meta-aramid is regarded as an ideal substrate for the next generation of insulating paper and film due to its excellent heat resistance and insulation performance. However, the application cost of meta-aramid insulating paper does not match its performance strength, especially its bulk insulation strength still needs to be improved. In order to match the thermodynamic stability level of meta-aramid, doping with inorganic ceramic fillers with higher heat resistance and insulation performance is an effective modification method. However, the compatibility between nano-fillers and polymers is always poor, and there are serious interfacial problems. Summary of the Invention

[0003] To solve the problems raised in the above background technique, the present invention provides a preparation method of a meta-aramid / nano-TiO2 composite insulating paper with high insulation strength, which has the characteristics of improving the binding ability between nano-fillers and aramid paper through the synergistic effect of dopamine coating and silane coupling agent, and effectively improving the breakdown voltage of the composite insulating paper by reducing the volume conductivity and increasing the carrier trap depth of the material.

[0004] To achieve the above object, the present invention provides the following technical solution: A preparation method of a meta-aramid / nano-TiO2 composite insulating paper with high insulation strength, comprising the following steps:

[0005] S1: Dopamine pretreatment of nano-TiO2;

[0006] S2: Coupling agent treatment of nano-TiO2;

[0007] S3: Preparation of a meta-aramid / nano-TiO2 composite insulating paper with high insulation strength.

[0008] Further in the present invention, the specific steps of S1 are as follows:

[0009] S11: Take TiO2, disperse it in deionized water, place it in a beaker, configure a 0.1 mol / L suspension, and adjust the pH of the suspension to 9.0;

[0010] S12: Add hydrochloric acid dopamine to the TiO2 suspension, and stir at 800 r / min at 25 °C for 4 h;

[0011] S13: After washing several times with deionized water, centrifuge the mixture at 1000 r / min, dry it at 60 °C for 5 h and then grind it. The obtained nanoparticles are denoted as D-TiO2 and reserved for use.

[0012] Further in the present invention, in the step S11, the mass-volume ratio of TiO2 to deionized water is 10:400 (g:ml).

[0013] Further in the present invention, in the step S12, the mass ratio of dopamine hydrochloride to TiO2 is 10:0.5.

[0014] Further in the present invention, the specific steps of S2 are as follows:

[0015] S21: Take KH550 solution, absolute ethanol and deionized water, place them in a beaker, stir at 500 r / min for 30 min at 60 °C to obtain a mixed solution;

[0016] S22: Add the D-TiO2 particles obtained in step S1 to the mixed solution, and continue to stir rapidly at 85 °C for 3 h to make them graft fully;

[0017] S23: After washing with deionized water, centrifuging and drying, modified nano-titanium dioxide is obtained, denoted as K-TiO2.

[0018] Further in the present invention, in the step S21, the volume ratio of KH550 solution, absolute ethanol and deionized water is 1:90:10.

[0019] Further in the present invention, in the step S22, the mass ratio of D-TiO2 to KH550 is 100:2.

[0020] Further in the present invention, the specific steps of S3 are as follows:

[0021] S31: Take mL of ultrapure water and add it to a beater, add dry precipitated fibers and chopped fibers to the beater, add the K-TiO2 obtained in step S2 to the beater, slowly add a hydroxymethyl cellulose dispersant, and set the stirring speed to 1500 r / min and stir evenly for 20 min;

[0022] S32: After setting up a papermaking platform, a circular insulating paper with a mass of 5 g is made on a paper former;

[0023] S33: Use a flat vulcanizing machine and a chromium-plated tungsten steel mold for hot pressing, set the hot pressing temperature to 200 °C, the pressure to 100 MPa, and hot press three times, 15 s each time, to prepare a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper.

[0024] Further in the present invention, in the step S31, the mass-volume ratio of ultrapure water to the hydroxymethyl cellulose dispersant is 400:1 (ml:g).

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. The present invention improves the binding ability between the nano-filler and the aramid paper through the synergistic effect of dopamine coating and silane coupling agent, and effectively improves the breakdown voltage of the composite insulating paper by reducing the volume conductivity and increasing the carrier trap depth of the material.

[0027] 2. Starting from the existing processes in the papermaking industry production, the present invention improves this process, which is simple to operate, convenient to implement, and low in cost, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is the preparation flow chart of the high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper of the present invention;

[0029] Figure 2 is the powder X-ray electron energy spectrum diagram of the present invention;

[0030] Figure 3 is the cross-sectional scanning electron microscope diagram of the present invention;

[0031] Figure 4 is the charge dissipation test result diagram of the present invention;

[0032] Figure 5 is the trap calculation result diagram of the present invention;

[0033] Figure 6 is the volume conductivity test result diagram of the present invention;

[0034] Figure 7 is the breakdown voltage test equipment diagram of the present invention;

[0035] Figure 8 is the breakdown voltage test result diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] Example 1

[0038] Please refer to Figure 1-8 , the present invention provides the following technical solutions: A preparation method of a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper, comprising the following steps:

[0039] S1: Dopamine pretreatment of nano-TiO2

[0040] S11: Take 10 g of TiO2, disperse it in 400 ml of deionized water, place it in a beaker, prepare a 0.1 mol / L suspension, and adjust the pH of the suspension to 9.0;

[0041] S12: Add 0.5 g of dopamine hydrochloride to the TiO2 suspension, and stir at 800 r / min at 25 °C for 4 h;

[0042] S13: After washing with deionized water multiple times, centrifuge the mixed solution at 1000 r / min, dry it at 60 °C for 5 h and then grind it. Denote the obtained nanoparticles as D-TiO2 for standby;

[0043] S2: Treatment of nano-TiO2 with coupling agent

[0044] S21: Take 1 ml of KH550 solution, 90 ml of absolute ethanol and 10 ml of deionized water, place them in a beaker, and stir at 500 r / min at 60 °C for 30 min to obtain a mixed solution;

[0045] S22: Add the D-TiO2 particles obtained in step S1 to the mixed solution. The mass ratio of D-TiO2 to KH550 is 100:2. Continue to stir rapidly at 85 °C for 3 h to make them graft fully;

[0046] S23: After washing, centrifuging and drying with deionized water, obtain the modified nano-titanium dioxide, denoted as K-TiO2;

[0047] S3: Preparation of high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper

[0048] S31: Take 2000 mL of ultrapure water and add it to a beater. Add the dried precipitated fibers and chopped fibers to the beater. Add the K-TiO2 obtained in step S2 to the beater. The mass fraction of K-TiO2 and the composite insulating paper is 1%. Slowly add 5 g of hydroxymethyl cellulose dispersant, and then set the stirring speed to 1500 r / min and stir evenly for 20 min;

[0049] S32: After setting up a papermaking platform, make a circular insulating paper with a mass of 5 g on a sheet former;

[0050] S33: Use a flat vulcanizer and a chromium-plated tungsten steel mold for hot pressing. Set the hot pressing temperature to 200 °C, the pressure to 100 MPa, and hot press three times, 15 s each time, to prepare a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper, denoted as K-1;

[0051] Control group 1

[0052] Add 2000 mL of ultrapure water to a beater. Add dry precipitated fibers and chopped fibers to the beater, and then add TiO₂ to the beater. The mass fraction of TiO₂ and composite insulating paper is 1%. After slowly adding 5 g of hydroxymethyl cellulose dispersant, set the stirring speed to 1500 r / min and stir evenly for 20 min. After setting up a papermaking platform, a circular insulating paper with a mass of 5 g is formed on a sheet former. Hot pressing is carried out using a flat vulcanizer and a chromium-plated tungsten steel mold. Set the hot pressing temperature to 200 °C and the pressure to 100 MPa. A total of three hot pressings are carried out, each for 15 s. The prepared meta-aramid / nano-TiO₂ composite insulating paper is denoted as T-1.

[0053] Example 2

[0054] Please refer to Figure 1-8 , the present invention provides the following technical solutions: A preparation method of a high-insulation-strength meta-aramid / nano-TiO₂ composite insulating paper, comprising the following steps:

[0055] S1: Dopamine pretreatment of nano-TiO₂

[0056] S11: Take 10 g of TiO₂, disperse it in 400 ml of deionized water, place it in a beaker, and prepare a suspension of 0.1 mol / L. Adjust the pH of the suspension to 9.0;

[0057] S12: Add 0.5 g of hydrochloric acid dopamine to the TiO₂ suspension, and stir at 800 r / min at 25 °C for 4 h;

[0058] S13: After washing with deionized water multiple times, centrifuge the mixture at 1000 r / min, dry it at 60 °C for 5 h, and then grind it. The obtained nanoparticles are denoted as D-TiO₂ and reserved for use;

[0059] S2: Coupling agent treatment of nano-TiO₂

[0060] S21: Take 1 ml of KH550 solution, 90 ml of absolute ethanol, and 10 ml of deionized water, place them in a beaker, and stir at 500 r / min at 60 °C for 30 min to obtain a mixed solution;

[0061] S22: Add the D-TiO₂ particles obtained in step S1 to the mixed solution. The mass ratio of D-TiO₂ to KH550 is 100:2. Continue to stir rapidly at 85 °C for 3 h to make them graft fully;

[0062] S23: After washing, centrifuging, and drying with deionized water, the modified nano-titanium dioxide is obtained, denoted as K-TiO₂;

[0063] S3: Preparation of a high-insulation-strength meta-aramid / nano-TiO₂ composite insulating paper

[0064] S31: Add 2000 mL of ultrapure water into a beater, add dry precipitated fibers and chopped fibers into the beater, add the K-TiO₂ obtained in step S2 into the beater. The mass fraction of K-TiO₂ and the composite insulating paper is 2%. After slowly adding 5 g of hydroxymethyl cellulose dispersant, set the stirring speed at 1500 r / min and stir evenly for 20 min;

[0065] S32: After setting up a papermaking platform, make a circular insulating paper with a mass of 5 g on a sheet former;

[0066] S33: Use a flat vulcanizing machine and a chromium-plated tungsten steel mold for hot pressing. Set the hot pressing temperature at 200 °C and the pressure at 100 MPa. Hot press three times in total, 15 s each time, to prepare a meta-aramid / nano-TiO₂ composite insulating paper with high insulation strength, denoted as K-2;

[0067] Control group 2

[0068] Add 2000 mL of ultrapure water into a beater, add dry precipitated fibers and chopped fibers into the beater, add TiO₂ into the beater. The mass fraction of TiO₂ and the composite insulating paper is 2%. After slowly adding 5 g of hydroxymethyl cellulose dispersant, set the stirring speed at 1500 r / min and stir evenly for 20 min. After setting up a papermaking platform, make a circular insulating paper with a mass of 5 g on a sheet former. Use a flat vulcanizing machine and a chromium-plated tungsten steel mold for hot pressing. Set the hot pressing temperature at 200 °C and the pressure at 100 MPa. Hot press three times in total, 15 s each time. The prepared meta-aramid / nano-TiO₂ composite insulating paper is denoted as T-2.

[0069] Example 3

[0070] Please refer to Figure 1-8 , the present invention provides the following technical solution: A preparation method of a meta-aramid / nano-TiO₂ composite insulating paper with high insulation strength, comprising the following steps:

[0071] S1: Dopamine pretreatment of nano-TiO₂

[0072] S11: Take 10 g of TiO₂, disperse it in 400 ml of deionized water, place it in a beaker, configure a 0.1 mol / L suspension, and adjust the pH of the suspension to 9.0;

[0073] S12: Add 0.5 g of hydrochloric acid dopamine into the TiO₂ suspension, and stir at 800 r / min at 25 °C for 4 h;

[0074] S13: After washing with deionized water for multiple times, centrifuge the mixed solution at 1000 r / min, dry it at 60 °C for 5 h and then grind it. Denote the obtained nanoparticles as D-TiO₂ for standby;

[0075] S2: Coupling agent treatment of nano-TiO2

[0076] S21: Take 1 ml of KH550 solution, 90 ml of absolute ethanol and 10 ml of deionized water, place them in a beaker, stir at 500 r / min for 30 min at 60 °C to obtain a mixed solution;

[0077] S22: Add the D-TiO2 particles obtained in step S1 to the mixed solution. The mass ratio of D-TiO2 to KH550 is 100:2, and continue to stir rapidly at 85 °C for 3 h to make them graft fully;

[0078] S23: After washing with deionized water, centrifuging and drying, the modified nano-titanium dioxide is obtained, denoted as K-TiO2;

[0079] S3: Preparation of high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper

[0080] S31: Take 2000 mL of ultrapure water and add it to a beater. Add the dried precipitated fibers and chopped fibers to the beater. Add the K-TiO2 obtained in step S2 to the beater. The mass fraction of K-TiO2 and the composite insulating paper is 3%. After slowly adding 5 g of hydroxymethyl cellulose dispersant, set the stirring speed to 1500 r / min and stir evenly for 20 min;

[0081] S32: After setting up a papermaking platform, a circular insulating paper with a mass of 5 g is made on a sheet former;

[0082] S33: Use a flat vulcanizing machine and a chromium-plated tungsten steel mold for hot pressing. Set the hot pressing temperature to 200 °C and the pressure to 100 MPa. Hot press three times, 15 s each time, to prepare a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper, denoted as K-3;

[0083] Control group 3

[0084] Take 2000 mL of ultrapure water and add it to a beater. Add the dried precipitated fibers and chopped fibers to the beater. Add TiO2 to the beater. The mass fraction of TiO2 and the composite insulating paper is 3%. After slowly adding 5 g of hydroxymethyl cellulose dispersant, set the stirring speed to 1500 r / min and stir evenly for 20 min. After setting up a papermaking platform, a circular insulating paper with a mass of 5 g is made on a sheet former. Use a flat vulcanizing machine and a chromium-plated tungsten steel mold for hot pressing. Set the hot pressing temperature to 200 °C and the pressure to 100 MPa. Hot press three times, 15 s each time, to prepare the meta-aramid / nano-TiO2 composite insulating paper, denoted as T-3.

[0085] Example 4

[0086] Please refer to Figure 1-8 , the present invention provides the following technical solution: A preparation method of a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper, comprising the following steps:

[0087] S1: Dopamine pretreatment of nano-TiO2

[0088] S11: Take 10 g of TiO2, disperse it in 400 ml of deionized water, place it in a beaker, configure a 0.1 mol / L suspension, and adjust the pH of the suspension to 9.0;

[0089] S12: Add 0.5 g of hydrochloric acid dopamine to the TiO2 suspension, and stir at 800 r / min at 25 °C for 4 h;

[0090] S13: After washing with deionized water multiple times, centrifuge the mixed solution at 1000 r / min, dry it at 60 °C for 5 h, and then grind it. The obtained nanoparticles are denoted as D-TiO2 and reserved for use;

[0091] S2: Coupling agent treatment of nano-TiO2

[0092] S21: Take 1 ml of KH550 solution, 90 ml of absolute ethanol and 10 ml of deionized water, place them in a beaker, and stir at 500 r / min at 60 °C for 30 min to obtain a mixed solution;

[0093] S22: Add the D-TiO2 particles obtained in step S1 to the mixed solution. The mass ratio of D-TiO2 to KH550 is 100:2, and continue to stir rapidly at 85 °C for 3 h to make them graft fully;

[0094] S23: After washing, centrifuging and drying with deionized water, the modified nano-titanium dioxide is obtained, denoted as K-TiO2;

[0095] S3: Preparation of high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper

[0096] S31: Add 2000 mL of ultrapure water to a beater, add dry precipitated fibers and chopped fibers to the beater, add the K-TiO2 obtained in step S2 to the beater. The mass fraction of K-TiO2 and the composite insulating paper is 4%. After slowly adding 5 g of hydroxymethyl cellulose dispersant, set the stirring speed to 1500 r / min and stir evenly for 20 min;

[0097] S32: After setting up a papermaking platform, a circular insulating paper with a mass of 5 g is made on a paper former;

[0098] S33: Hot pressing is carried out using a flat vulcanizing machine and a chromium-plated tungsten steel mold. The hot pressing temperature is set at 200 °C, the pressure is 100 MPa, and hot pressing is carried out three times, each time for 15 s, to prepare a meta-aramid / nano-TiO2 composite insulating paper with high insulation strength, denoted as K-4;

[0099] Control group 4

[0100] Add 2000 mL of ultrapure water to a beater, add dry precipitated fibers and chopped fibers to the beater, add TiO2 to the beater. The mass fraction of TiO2 and the composite insulating paper is 4%. After slowly adding 5 g of hydroxymethyl cellulose dispersant, the stirring speed is set at 1500 r / min and stirred evenly for 20 min. After building a papermaking platform, a circular insulating paper with a mass of 5 g is made on a paper former. Hot pressing is carried out using a flat vulcanizing machine and a chromium-plated tungsten steel mold. The hot pressing temperature is set at 200 °C, the pressure is 100 MPa, and hot pressing is carried out three times, each time for 15 s. The prepared meta-aramid / nano-TiO2 composite insulating paper is denoted as T-4.

[0101] Instruction manual attachment Figure 2 is the X-ray photoelectron spectroscopy diagram of TiO2 and K-TiO2 samples. In addition to the Ti peak (KLL) and O peak (1s) of TiO2 itself, the spectrum after treatment with silane coupling agent shows characteristic peaks of Si (3N4) specific to KH550 and N (1s) also contained in dopamine, indicating the successful grafting of dopamine and silane coupling agent;

[0102] Instruction manual attachment Figure 3 is the cross-sectional scanning electron microscopy diagram of the nano-aramid composite material. It can be seen that the surface of pure aramid paper is smooth after being magnified 3000 times and there are no rough grooves. When a small amount of TiO2 is added, it shows a spot-like distribution on the aramid fibers. As the mass fraction of nano-particles increases, the agglomeration phenomenon becomes more obvious, and a sheet-like substance with a certain thickness is formed on the fiber surface. However, the size of the nano-particles after modification of titanium dioxide is smaller than that before modification, the dispersibility is improved, and the agglomeration phenomenon is improved;

[0103] Instruction manual attachment Figure 4 is the charge dissipation test result. The faster the surface charge dissipation rate, the easier it is to break away from the trap, thus participating in the discharge, intensifying the flashover, and reducing the insulation performance of the polymer;

[0104] Instruction manual attachment Figure 5 is the trap calculation result. It can be seen from the figure that as the mass fraction increases, the shallow traps at the interface transform into deep traps, and the depth of the deep traps increases, which is consistent with the charge dissipation test result;

[0105] Instruction manual attachment Figure 6The results of volume conductivity test show that as the mass fraction of nanoparticles increases from 0% to 5%, the volume conductivity decreases significantly. The paper sample doped with TiO2 decreases saturatedly, and the K series shows a trend of decreasing first and then increasing. Among them, the volume conductivity of K-2 insulating paper sample is the lowest, which is 5.02×10-17S / m, which is 83% lower than that of pure aramid paper.

[0106] Instructions attached Figure 7 The equipment is used for breakdown voltage testing. A column-plate electrode is used for positive polarity DC breakdown characteristic testing. The column electrode is connected to a high-power DC source through a protective resistor, and the plate electrode is grounded. The power supply voltage boost speed is 0.2 kV / s. An oscilloscope series voltage probe (TrekP6015b) is used to test the voltage amplitude when breakdown occurs. The test temperature is 25±2℃, the humidity is 15±1%RH, and each round of testing is repeated 10 times.

[0107] Instructions attached Figure 8 The breakdown voltage test results show that the pressure resistance of the paper samples after doping and modification of titanium dioxide has been improved to a certain extent compared with before modification. The breakdown voltage of the K-2 paper sample is increased by 54% compared with pure aramid.

[0108] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper, characterized in that It includes the following steps: S1: Dopamine pretreatment of nano-TiO2 S11: Take TiO2, disperse it in deionized water, place it in a beaker, prepare a 0.1 mol / L suspension, and adjust the pH of the suspension to 9.0; S12: Add dopamine hydrochloride to the TiO2 suspension, stir at 800 r / min at 25 °C for 4 h; S13: After washing with deionized water for multiple times, centrifuge the mixed solution at 1000 r / min, dry it at 60 °C for 5 h and then grind it. Denote the obtained nanoparticles as D-TiO2 for standby; S2: Coupling agent treatment of nano-TiO2 S21: Take KH550 solution, anhydrous ethanol and deionized water, place them in a beaker, stir at 500 r / min at 60 °C for 30 min to obtain a mixed solution; S22: Add the D-TiO2 particles obtained in step S1 to the mixed solution, continue to stir rapidly at 85 °C for 3 h to make them graft fully; S23: After washing, centrifuging and drying with deionized water, obtain modified nano-titanium dioxide, denoted as K-TiO2; S3: Prepare meta-aramid / nano-TiO2 composite insulating paper with high insulation strength S31: Add mL of ultrapure water into a beater, add dry precipitated fibers and chopped fibers into the beater, add the K-TiO2 obtained in step S2 into the beater, slowly add a hydroxymethyl cellulose dispersant, and then set the stirring speed to 1500 r / min and stir evenly for 20 min; S32: After setting up a papermaking platform, make a circular insulating paper with a mass of 5 g on a sheet former; S33: Use a flat vulcanizer and a chromium-plated tungsten steel mold for hot pressing. Set the hot pressing temperature to 200 °C and the pressure to 100 MPa. Hot press three times in total, 15 s each time, to prepare meta-aramid / nano-TiO2 composite insulating paper with high insulation strength.

2. The preparation method of a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper according to claim 1, characterized in that: In the step S11, the mass-volume ratio of TiO2 to deionized water is 10:400 (g:ml).

3. The preparation method of a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper according to claim 2, wherein: In the step S12, the mass ratio of dopamine hydrochloride to TiO2 is 10:0.

5.

4. The preparation method of a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper according to claim 3, characterized in that: In the step S21, the volume ratio of KH550 solution, anhydrous ethanol and deionized water is 1:90:

10.

5. The preparation method of a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper according to claim 4, characterized in that: In the step S22, the mass ratio of D-TiO2 to KH550 is 100:

2.

6. The preparation method of a high-insulation-strength meta-aramid / nano-TiO2 composite insulating paper according to claim 5, characterized in that: In the step S31, the mass-volume ratio of ultrapure water to hydroxymethyl cellulose dispersant is 400:1 (ml:g).

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