High-breakdown-field-strength bast fiber / other plant fiber mixed insulation paper and preparation method thereof

Abstract

The invention provides high-breakdown-field-strength bast fiber / other plant fiber mixed insulation paper and a preparation method thereof. The preparation method comprises the following steps: preparing bast paper pulp; beating and purifying the bast paper pulp to obtain high-purity insulating bast fiber paper pulp; mixing the high-purity insulating bast fiber paper pulp with other plant fiber paper pulp according to a preset proportion, and defibering to obtain mixed pulp; wherein the other plant fiber paper pulp is one of softwood pulp, hardwood pulp and bamboo pulp; and performing papermaking and hot pressing on the basis of the mixed pulp to obtain the mixed papermaking insulation paper. The mixed insulation paper oil paper insulation prepared by the invention has relatively high breakdown field strength which is higher than the use standard of unbleached impregnated needlebush insulation paper.

Description

Technical Field

[0001] The invention belongs to the field of electrical insulation materials, and in particular relates to a high breakdown field strength bast fiber / other plant fiber mixed insulation paper and a preparation method thereof. Background Art

[0002] During the operation of power equipment, its main insulation system is subjected to various forms of stress, such as electricity, magnetism, heat, and force. Insulation paper is a key material for the main insulation system of many power equipment. Its performance is related to the short-term performance and long-term service life of power equipment, which in turn affects the safe and stable operation of the power transmission and transformation system. Therefore, the design and preparation of insulation paper is a key technical issue to ensure the stable operation of power equipment and power grid.

[0003] At present, my country has a large demand for medium- and high-end insulation paper with excellent dielectric and mechanical properties. However, my country's screening of plant fiber raw materials and mastery of key data in pulp production are relatively weak. At present, the production and preparation of insulation paper mainly uses plant fiber as raw material, or more precisely, perennial coniferous wood as raw material. With the decreasing forest resources, it is very important to find other equally suitable plant fiber materials to prepare medium- and high-end insulation paper with excellent performance. Summary of the invention

[0004] The purpose of the present invention is to provide a high breakdown field strength bast fiber / other plant fiber mixed insulation paper and a preparation method thereof to overcome the problems existing in the prior art. The mixed insulation paper oil paper insulation prepared by the present invention has a high breakdown field strength, which is higher than the use standard of unbleached impregnated coniferous wood insulation paper.

[0005] The present invention is achieved through the following technical solutions: A method for preparing high breakdown field strength bast fiber / other plant fiber mixed insulation paper comprises the following steps: Step 1: preparing bast pulp; Step 2: beating and purifying the bast pulp to obtain high-purity insulating bast fiber pulp; Step 3: mixing high-purity insulating bast fiber pulp and other plant fiber pulp in a preset ratio and then dispersing them to obtain a mixed pulp; wherein the other plant fiber pulp is one of coniferous wood pulp, hardwood wood pulp and bamboo pulp; Step 4: Papermaking and hot pressing are performed based on the mixed slurry to obtain mixed insulating paper.

[0006] Furthermore, the bast pulp is celtis sinensis bark pulp, mulberry bark pulp, goose bark pulp, hemp pulp or flax pulp.

[0007] Furthermore, the step 1 specifically includes: processing the bast pulp raw material into a length of 5 cm, soaking for 12 hours, and then using the caustic soda-anthraquinone method to cook the bast pulp raw material for pulping to obtain bast pulp.

[0008] Furthermore, the step 2 specifically comprises: performing alkaline extraction on the bast pulp using an alkaline solution prepared with sodium hydroxide, removing pectin from the bast pulp using a pectinase solution prepared with pectinase after the alkaline extraction, beating the obtained bast pulp to cut the fibers and make it fibrillate, and then replacing the sodium ions with a magnesium bicarbonate solution to obtain high-purity insulating bast fiber pulp, which is then stored in an environment of 5°C for future use after pulping.

[0009] Furthermore, in step 3, the absolute dry mass of the high-purity insulating bast fiber pulp is 10%-40% of the absolute dry mass of other plant fiber pulps.

[0010] Furthermore, in step 3, the speed of degassing is 15000r.

[0011] Furthermore, the step 4 specifically includes: making a hand sheet based on the mixed slurry in a deionized water environment, then drying, and finally hot pressing and drying to obtain a mixed insulating paper.

[0012] Furthermore, the basis weight of the hand sheet is 120 g / cm 3 .

[0013] Furthermore, the drying temperature is 98° C. and the pressure is 1 bar, and the hot press drying temperature is 105° C. and the pressure is 15 MPa.

[0014] A high breakdown field strength bast fiber / other plant fiber mixed insulation paper is prepared by adopting the above preparation method.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention uses bast pulp made of bast pulp raw material, and obtains high-purity insulating bast fiber pulp after beating and purifying the bast pulp. Different plant fiber pulps are selected, and the bast fiber and other plant fiber pulps (coniferous wood pulp, hardwood pulp, bamboo pulp, etc.) are mixed according to different mass ratios, and mixed insulating paper with different bast fiber contents is obtained through papermaking, drying, and hot pressing. The fiber morphology of the bast fiber is reasonably controlled by beating, and the ratio of the bast fiber to other plant fibers is adjusted to achieve the purpose of reasonably adjusting the structure of the insulating paper sheet, and finally the oil-impregnated insulating paper has a higher AC and DC breakdown field strength, providing a new idea for the development of mid-to-high-end insulating paper. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. The following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 The Weibull distribution diagram of AC breakdown field strength of the mixed insulation paper prepared in the embodiment; Figure 2 This is the SEM image of the mixed insulation paper in Example 1. DETAILED DESCRIPTION

[0018] The present invention is described in detail below: A method for preparing high breakdown field strength bast fiber / other plant fiber mixed insulation paper comprises the following steps: Step 1: preparing bast pulp, wherein the bast pulp is tung oil tree bark pulp, mulberry bark pulp, goose bark pulp, hemp pulp or flax pulp; specifically, the bast pulp raw material is processed into a length of 5 cm, soaked for 12 hours, and then the bast pulp raw material is cooked by caustic soda-anthraquinone method to obtain bast pulp; Step 2: beating and purifying the bast pulp to obtain high-purity insulating bast fiber pulp; specifically, using an alkaline solution prepared with sodium hydroxide to perform alkali extraction on the bast pulp, and after the alkali extraction, using a pectinase solution prepared with pectinase to remove pectin from the bast pulp, then beating the obtained bast pulp to cut the fibers and make it fibrillated, and then using a magnesium bicarbonate solution to replace sodium ions to obtain high-purity insulating bast fiber pulp, and storing it at low temperature for future use after pulping; Step 3: mixing high-purity insulating bast fiber pulp and other plant fiber pulps in a preset ratio and then deflaking them in a deflaking machine to obtain a mixed pulp; wherein the other plant fiber pulp is one of coniferous wood pulp, hardwood wood pulp and bamboo pulp; wherein the mass of the high-purity insulating bast fiber pulp is 10%-40% of the mass of the other pulps, and the deflaking rotation number is 15000r; Step 4: Based on the mixed slurry, use the Cathay papermaking system to make paper with a weight of 120 g / cm2 in a deionized water environment 3 The hand-coated sheets were placed in a drying system with a temperature of 98 °C and a pressure of 1 bar for preliminary drying. Finally, the paper was hot-pressed and dried using a flat-plate hot press at 105 °C and 15 MPa to obtain mixed insulating paper.

[0019] The insulating paper prepared by the present invention is obtained by the above steps. Through specific processes such as cooking, pulping, and chemical purification, bast pulp with specific fiber characteristics is obtained. By mixing bast fibers with other plant fibers, the structure and physical and chemical properties of the insulating paper sheets are changed, and the breakdown field strength of the oil-impregnated paper is finally improved, providing a new idea for the research and development of mid-to-high-end insulating paper. my country is rich in bast resources, which are short-term growing plants, and the price of bast raw materials is low, which reduces the production cost of insulating paper and greatly improves the economy and environmental protection.

[0020] The following will describe the embodiments of the present invention in detail with reference to the examples. The implementation case is a preferred embodiment of the present invention and the scope of the present invention cannot be limited thereto. In the following examples, the methods and experimental equipment used are conventional methods and instruments unless otherwise specified. In the following examples, several representative bast fibers among the above bast fibers are specifically described.

[0021] Example 1 This embodiment provides a method for preparing a mixed insulating paper of euphorbia cerasifera bark fiber and coniferous wood fiber with high breakdown field strength, comprising the following steps: Step 1: Prepare the pulp of Pteris tannin bark by steaming. The Pteris tannin bark raw material was processed into 5 cm long pieces and soaked for 12 hours. The raw material was steamed and pulped by caustic soda-anthraquinone method.

[0022] Step 2: Pulping and pulp purification. After the cooking is completed, the elm bark pulp is subjected to alkali extraction with an alkaline solution prepared with sodium hydroxide. After the alkali extraction is completed, the elm bark pulp is treated with a pectinase solution prepared with pectinase to remove pectin. The elm bark pulp is then pulped with a Wall-E pulper to cut the fibers and make it fibrillated. In order to reduce the sodium ion content in the elm bark pulp, a magnesium bicarbonate solution is used to replace the sodium ions. Finally, a high-purity elm bark pulp is obtained, which is stored at low temperature for later use after pulping. Step 3: Mix the elmwood bark pulp and commercial softwood pulp. Mix the elmwood bark pulp into the softwood pulp at a 10% absolute dry mass ratio. Deflake and mix in a deflaker at 15,000 revolutions to fully mix the two pulps.

[0023] Step 4: Papermaking and hot pressing. Then, the papermaking system was used to make paper with a weight of 120 g / cm2 in a deionized water environment. 3 The paper was then placed in a drying system at 98°C and 1 bar for preliminary drying. Finally, the paper was subjected to secondary hot pressing and drying at 105°C and 15 MPa using a flat hot press to obtain a mixed insulating paper sheet of euphorbia cerasifera bark fiber and coniferous wood fiber. The SEM image is shown in Figure 2. Figure 2 shown. Embodiment 2-4 The difference between Example 2-4 and Example 1 is that in step 3, the cinnamomum tiliaceum bark pulp is mixed with coniferous wood pulp at an absolute dry mass ratio of 20%, 30% and 40%, respectively.

[0024] Performance test: The insulating paper mixed with the euphorbia cerasifera bark fiber prepared in Examples 1-4 was placed in an oven at 105°C for 24 hours to remove moisture, and then vacuum-impregnated in KI50X insulating mineral oil for 24 hours to obtain an oil-impregnated paper sample, and the AC and DC breakdown field strengths of the oil-impregnated paper were tested respectively. The AC and DC breakdown field strengths of the insulating oil-impregnated paper containing different proportions of euphorbia cerasifera bark fiber are shown in Table 1 and Figure 1 As shown: Table 1 Breakdown field strength of softwood insulating oil-impregnated paper containing different proportions of cinnamomum tiliaceum bark fibers

[0025] Example 5 This embodiment provides a method for preparing a mixed insulation paper of mulberry fiber and hardwood fiber with high breakdown field strength, comprising the following steps: Step 1: Cooking to prepare mulberry pulp. The mulberry pulp raw material is processed into 5 cm long pieces and soaked for 12 hours. The raw material is cooked by caustic soda-anthraquinone method to prepare pulp.

[0026] Step 2: Pulping and pulp purification. After the cooking is completed, the mulberry pulp is subjected to alkaline extraction with an alkaline solution prepared with sodium hydroxide. After the alkaline extraction is completed, the mulberry pulp is treated with a pectinase solution prepared with pectinase to remove pectin. The obtained mulberry pulp is then beaten with a Wall-E pulper to cut the fibers and make it fibrillated. In order to reduce the sodium ion content in the mulberry pulp, the sodium ions are replaced with a magnesium bicarbonate solution. Finally, high-purity mulberry pulp is obtained, which is stored at low temperature for future use after pulping.

[0027] Step 3: Mix mulberry pulp and other pulps. Select commercial hardwood pulp. Mix mulberry pulp with hardwood pulp at a 10% absolute dry mass ratio, and deflake and mix in a deflaker for 15,000 revolutions to fully mix the two pulps.

[0028] Step 4: Papermaking and hot pressing. Then, the papermaking system was used to make paper with a weight of 120 g / cm2 in a deionized water environment. 3 The paper was then placed in a drying system at 98 °C and 1 bar for preliminary drying. Finally, the paper was subjected to secondary hot pressing and drying at 105 °C and 15 MPa using a flat hot press to obtain a mixed insulating paper sheet of mulberry fiber and hardwood fiber.

[0029] Embodiment 6-8 The difference between Example 6-8 and Example 5 is that in step 3, mulberry pulp is mixed with hardwood pulp at an absolute dry mass ratio of 20%, 30% and 40%, respectively.

[0030] Performance test: The mulberry fiber mixed insulation paper prepared in Examples 5-8 was placed in a 105°C oven for 24 hours to remove moisture, and then vacuum impregnated in KI50X insulating mineral oil for 24 hours to obtain oil-impregnated paper samples, and the AC and DC breakdown field strengths of the oil-impregnated paper were tested respectively. The AC and DC breakdown field strengths of the insulating oil-impregnated paper containing different proportions of mulberry fiber are shown in Table 2 below: Table 2 Breakdown field strength of hardwood insulation oil-impregnated paper containing different proportions of mulberry fiber

[0031] Example 9 This embodiment 3 provides a method for preparing a mixed insulation paper of mulberry fiber and bamboo fiber with high breakdown field strength, comprising the following steps: Step 1: Cooking to prepare mulberry pulp. The mulberry pulp raw material is processed into 5 cm long and soaked for 12 hours. The raw material is cooked by caustic soda-anthraquinone method to prepare pulp.

[0032] Step 2: Pulping and pulp purification. After the cooking is completed, the mulberry pulp is subjected to alkali extraction with an alkaline solution prepared with sodium hydroxide. After the alkali extraction is completed, the mulberry pulp is treated with a pectinase solution prepared with pectinase to remove pectin. The obtained mulberry pulp is then pulped with a Wall-E pulper to cut the fibers and make it fibrillated. In order to reduce the sodium ion content in the mulberry pulp, the sodium ions are replaced with a magnesium bicarbonate solution. Finally, high-purity mulberry pulp is obtained, which is stored at low temperature for future use after pulping.

[0033] Step 3: Mix mulberry pulp and other pulps. Select commercial bamboo pulp. Mix mulberry pulp with bamboo pulp at a 10% absolute dry mass ratio, and deflake and mix in a deflaker for 15,000 revolutions to fully mix the two pulps.

[0034] Step 4: Papermaking and hot pressing. Then, the papermaking system was used to make paper with a weight of 120 g / cm2 in a deionized water environment. 3 The paper was then placed in a drying system at 98 °C and 1 bar for preliminary drying. Finally, the paper was subjected to secondary hot pressing and drying at 105 °C and 15 MPa using a flat hot press to obtain a mixed insulation paper sheet of mulberry fiber and bamboo fiber. Examples 10-12 The difference between Examples 10-12 and Example 9 is that in step 3, mulberry pulp is mixed with bamboo pulp at an absolute dry mass ratio of 20%, 30%, and 40%, respectively.

[0035] Performance test: The mulberry fiber mixed insulation paper prepared in Examples 9-12 was placed in a 105°C oven for 24 hours to remove moisture, and then vacuum impregnated in KI50X insulating mineral oil for 24 hours to obtain oil-impregnated paper samples, and the AC and DC breakdown field strengths of the oil-impregnated paper were tested respectively. The AC and DC breakdown field strengths of the above-mentioned insulating oil-impregnated paper containing different proportions of mulberry fiber are shown in Table 3 below: Table 3 Breakdown field strength of bamboo fiber insulation oil-impregnated paper containing different proportions of mulberry fiber

[0036] Example 13 This embodiment provides a method for preparing a mixed insulating paper of goose skin fiber and coniferous wood fiber with high breakdown field strength, comprising the following steps: Step 1: Cooking to prepare goose skin pulp. The goose skin pulp raw material was processed into 5 cm length and soaked for 12 hours. The raw material was cooked by caustic soda-anthraquinone method for pulping.

[0037] Step 2: Pulping and pulp purification. After the cooking is completed, the goose skin pulp is subjected to alkaline extraction with an alkaline solution prepared with sodium hydroxide. After the alkaline extraction is completed, the goose skin pulp is treated with a pectinase solution prepared with pectinase to remove pectin. The obtained goose skin pulp is then pulped with a Wall-E pulper to cut the fibers and make it fibrillated. In order to reduce the sodium ion content in the goose skin pulp, the sodium ions are replaced with a magnesium bicarbonate solution. Finally, high-purity goose skin pulp is obtained, which is stored at low temperature for future use after pulping. Step 3: Mixing goose skin pulp with other pulps. Select commercial softwood pulp. Mix goose skin pulp with softwood pulp at a 10% absolute dry mass ratio, and deflake and mix in a deflaker for 15,000 revolutions to fully mix the two pulps.

[0038] Step 4: Papermaking and hot pressing. Then, the papermaking system was used to make paper with a weight of 120 g / cm2 in a deionized water environment. 3 The paper was then placed in a drying system at 98°C and 1 bar for preliminary drying. Finally, the paper was subjected to secondary hot pressing and drying at 105°C and 15 MPa using a flat hot press to obtain a hand-made insulating paper sheet of goose skin fiber and coniferous wood fiber. Examples 14-16 The difference between Examples 14-16 and Example 13 is that in step 3, goose skin pulp is mixed into softwood pulp at an absolute dry mass ratio of 20%, 30%, and 40%, respectively.

[0039] Performance test: The Yanpi fiber mixed insulation paper prepared in Examples 13-16 was placed in a 105°C oven for 24 hours to remove moisture, and then vacuum impregnated in KI50X insulating mineral oil for 24 hours to obtain oil-impregnated paper samples, and the AC and DC breakdown field strengths of the oil-impregnated paper were tested respectively. The AC and DC breakdown field strengths of the insulating oil-impregnated paper containing different proportions of Yanpi fiber are shown in Table 4 below: Table 4 Breakdown field strength of softwood fiber insulation oil-impregnated paper containing different proportions of goose skin fiber

[0040] Embodiment 17 This embodiment provides a method for preparing a mixed insulation paper of kenaf fiber and coniferous wood fiber with high breakdown field strength, comprising the following steps: Step 1: Cooking to prepare kenaf pulp. The kenaf pulp raw material is processed into 5 cm lengths and soaked for 12 hours. The raw material is cooked by caustic soda-anthraquinone method to prepare pulp.

[0041] Step 2: Pulping and pulp purification. After the cooking is completed, the kenaf pulp is subjected to alkaline extraction with an alkaline solution prepared with sodium hydroxide. After the alkaline extraction is completed, the kenaf pulp is treated with a pectinase solution prepared with pectinase to remove pectin. The obtained kenaf pulp is then pulped with a Wall-E pulper to cut the fibers and make it fibrillated. In order to reduce the sodium ion content in the kenaf pulp, the sodium ions are replaced with a magnesium bicarbonate solution. Finally, high-purity kenaf pulp is obtained, which is stored at low temperature for future use after pulping. Step 3: Mix kenaf pulp with other pulps. Select commercial softwood pulp. Mix kenaf pulp with softwood pulp at a 10% absolute dry mass ratio, and deflake and mix in a deflaker for 15,000 revolutions to fully mix the two pulps.

[0042] Step 4: Papermaking and hot pressing. Then, the papermaking system was used to make paper with a weight of 120 g / cm2 in a deionized water environment. 3 The paper was then placed in a drying system at 98 °C and 1 bar for preliminary drying. Finally, the paper was subjected to secondary hot pressing and drying at 105 °C and 15 MPa using a flat hot press to obtain a mixed insulating paper sheet of kenaf fiber and coniferous wood fiber. Examples 18-20 The difference between Examples 18-20 and Example 17 is that in step 3, kenaf pulp is mixed with coniferous wood pulp at an absolute dry mass ratio of 20%, 30%, and 40%, respectively.

[0043] Performance test: The kenaf fiber mixed insulation paper prepared in Examples 17-20 was placed in a 105°C oven for 24 hours to remove moisture, and then vacuum impregnated in KI50X insulating mineral oil for 24 hours to obtain oil-impregnated paper samples, and the AC and DC breakdown field strengths of the oil-impregnated paper were tested respectively. The AC and DC breakdown field strengths of the insulating oil-impregnated paper containing different proportions of kenaf fiber are shown in Table 5 below: Table 5 Breakdown field strength of softwood fiber insulation oil-impregnated paper containing different proportions of kenaf fiber

[0044] Embodiment 21 This embodiment provides a method for preparing a mixed insulating paper of flax fiber and hardwood fiber with high breakdown field strength, comprising the following steps: Step 1: Cooking to prepare flax pulp. The flax pulp raw material is processed into 5 cm long pieces and soaked for 12 hours. The raw material is cooked by caustic soda-anthraquinone method to prepare pulp.

[0045] Step 2: Pulping and pulp purification. After the cooking is completed, the flax pulp is subjected to alkaline extraction with an alkaline solution prepared with sodium hydroxide. After the alkaline extraction is completed, the flax pulp is treated with a pectinase solution prepared with pectinase to remove pectin. The obtained flax pulp is then pulped with a Wall-E pulper to cut the fibers and make it fibrillated. In order to reduce the sodium ion content in the flax pulp, the sodium ions are replaced with a magnesium bicarbonate solution. Finally, a relatively pure flax pulp is obtained, which is stored at low temperature for later use after pulping. Step 3: Mix flax pulp with other pulps. Select commercial hardwood pulp. Mix flax pulp with hardwood pulp at a 10% absolute dry mass ratio, and deflake and mix in a deflaker for 15,000 revolutions to fully mix the two pulps.

[0046] Step 4: Papermaking and hot pressing. Then, the papermaking system was used to make paper with a weight of 120 g / cm2 in a deionized water environment. 3 The paper was then placed in a drying system at 98 °C and 1 bar for preliminary drying. Finally, the paper was subjected to secondary hot pressing and drying at 105 °C and 15 MPa using a flat hot press to obtain a mixed insulating paper sheet of flax fiber and hardwood fiber. Examples 22-24 The difference between Examples 22-24 and Example 21 is that in step 3, flax pulp is mixed with hardwood pulp at an absolute dry mass ratio of 20%, 30% and 40%, respectively.

[0047] Performance test: The flax fiber mixed insulation paper prepared in Examples 21-24 was placed in a 105°C oven for 24 hours to remove moisture, and then vacuum impregnated in KI50X insulating mineral oil for 24 hours to obtain oil-impregnated paper samples, and the AC and DC breakdown field strengths of the oil-impregnated paper were tested respectively. The AC and DC breakdown field strengths of the above-mentioned insulating oil-impregnated paper containing different proportions of flax fiber are shown in Table 6 below: Table 6 Breakdown field strength of hardwood insulating oil impregnated paper containing different proportions of flax fiber

[0048] In summary, it can be seen that mixing bast fibers to improve the breakdown field strength of plant fiber insulation paper and oil-impregnated paper is a feasible technical route. By mixing bast fibers, the AC breakdown field strength of plant fiber insulation paper and oil-impregnated paper can be increased by up to 24.68%, and the DC breakdown field strength can be increased by up to 35.76%. The technical route of mixed bast fiber filling plant fiber insulation proposed in this application has important guiding significance for the manufacture of transformer paper.

[0049] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing high breakdown field strength bast fiber / other plant fiber mixed insulation paper, characterized in that: The following steps are involved: Step 1: preparing bast pulp; Step 2: beating and purifying the bast pulp to obtain high-purity insulating bast fiber pulp; Step 3: mixing high-purity insulating bast fiber pulp and other plant fiber pulp in a preset ratio and then dispersing them to obtain a mixed pulp; wherein the other plant fiber pulp is one of coniferous wood pulp, hardwood wood pulp and bamboo pulp; Step 4: Papermaking and hot pressing are performed based on the mixed slurry to obtain mixed insulating paper.

2. The method for preparing a high breakdown field strength bast fiber / other plant fiber mixed insulation paper according to claim 1, characterized in that: The bast pulp is celtis sinensis bark pulp, mulberry bark pulp, goose bark pulp, hemp pulp or flax pulp.

3. The method for preparing a high breakdown field strength bast fiber / other plant fiber mixed insulation paper according to claim 1, characterized in that: The step 1 specifically includes: processing the bast pulp raw material into a length of 5 cm, soaking for 12 hours, and then using the caustic soda-anthraquinone method to cook the bast pulp raw material for pulping to obtain bast pulp.

4. The method for preparing a high breakdown field strength bast fiber / other plant fiber mixed insulation paper according to claim 1, characterized in that: The step 2 specifically comprises: performing alkaline extraction on the bast pulp using an alkaline solution prepared with sodium hydroxide, removing pectin from the bast pulp using a pectinase solution prepared with pectinase after the alkaline extraction, beating the obtained bast pulp to cut the fibers and make it fibrillate, and then replacing sodium ions with a magnesium bicarbonate solution to obtain high-purity insulating bast fiber pulp, which is then stored in an environment of 5°C for future use after pulping.

5. The method for preparing a high breakdown field strength bast fiber / other plant fiber mixed insulation paper according to claim 1, characterized in that: In the step 3, the absolute dry mass of the high-purity insulating bast fiber pulp is 10%-40% of the absolute dry mass of other plant fiber pulps.

6. The method for preparing a high breakdown field strength bast fiber / other plant fiber mixed insulation paper according to claim 1, characterized in that: In step 3, the speed of degassing is 15000r.

7. The method for preparing a high breakdown field strength bast fiber / other plant fiber mixed insulation paper according to claim 1, characterized in that: The step 4 specifically includes: making a hand sheet based on the mixed slurry in a deionized water environment, then drying it, and finally hot pressing and drying it to obtain a mixed insulating paper.

8. The method for preparing a high breakdown field strength bast fiber / other plant fiber mixed insulation paper according to claim 7, characterized in that: The basis weight of the hand sheet is 120 g / cm 3 .

9. The method for preparing a high breakdown field strength bast fiber / other plant fiber mixed insulation paper according to claim 7, characterized in that: The drying temperature is 98°C and the pressure is 1 bar, and the hot press drying temperature is 105°C and the pressure is 15 MPa.

10. A high breakdown field strength bast fiber / other plant fiber mixed insulation paper, characterized in that: The method is prepared by the method according to any one of claims 1 to 9.

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