Aramid insulation paper preparation method and system

Abstract

This invention proposes a method and system for preparing aramid insulating paper. The method involves adding a chitosan aqueous solution to an aramid chromatographic fiber dispersion and ultrasonically stirring. Then, the aramid chromatographic fiber-chitosan suspension is added to distilled water and sequentially filtered, washed, and dried to obtain chitosan-modified aramid chromatographic fibers. Meta-aramid chopped fibers, meta-aramid precipitated fibers, and chitosan-modified aramid chromatographic fibers are sequentially pulped and dispersed. The first, second, and third dispersions are mixed and stirred according to a preset ratio to obtain a mixed aramid fiber slurry. Finally, chitosan-modified aramid insulating paper is obtained using the mixed aramid fiber slurry and a preset papermaking method. This method solves the problem of cumbersome and limited operation leading to inaccurate results in existing technologies for detecting localized overheating of transformer windings, significantly improving the accuracy of the detection results.

Description

Technical Field

[0001] This invention relates to the field of aramid insulating paper, and more particularly to a method and system for preparing aramid insulating paper. Background Technology

[0002] During operation, transformers may experience localized heating due to material degradation, excessive load, or other factors, which can lead to malfunctions or burnout in severe cases. Accurate monitoring in the early stages of localized heating allows for proactive intervention and accident prevention. Aramid insulating paper, due to its excellent mechanical, dielectric, and insulating properties, is widely used in transformer windings.

[0003] Currently, there are two main methods for detecting localized overheating in transformer windings. One method relies on traditional temperature sensors or infrared thermal imagers. While this method can monitor the temperature of the insulating paper, it requires specialized equipment and personnel and has limitations in detecting localized overheating. The other method detects specific small-molecule substances produced after the pyrolysis of the insulating paper, such as furfural. This method is limited to conventional plant fiber insulating paper and relies on the decomposition products of furfural and other insulating paper for detection. Due to the complexity of the decomposition products and the unclear correlation between them and localized overheating, it is currently only applicable to conventional plant fiber insulating paper and is not suitable for specialty papers such as aramid insulating paper. Summary of the Invention

[0004] Based on the above problems, this invention proposes a method for preparing aramid insulating paper, which solves the problem that the existing technology for detecting local overheating of transformer windings is cumbersome and has limitations, leading to inaccurate detection results.

[0005] To achieve the above objectives, embodiments of the present invention provide a method for preparing aramid insulating paper, comprising:

[0006] An aramid-chitosan suspension is obtained by adding the chitosan aqueous solution to the aramid chromatographic fiber dispersion and then ultrasonically stirring it; wherein the aramid chromatographic fiber dispersion is obtained by adding meta-aramid precipitated fibers to a dimethyl sulfoxide solution and then ultrasonically stirring it.

[0007] By adding the aramid chromatographic fiber-chitosan suspension to distilled water and sequentially filtering, washing, and drying, chitosan-modified aramid chromatographic fibers are obtained.

[0008] By sequentially pulping and dispersing meta-aramid short fibers, meta-aramid precipitated fibers, and chitosan-modified aramid chromatographic fibers, a first dispersion, a second dispersion, and a third dispersion are obtained.

[0009] The first dispersion, the second dispersion and the third dispersion are mixed and stirred in a preset ratio to obtain a mixed aramid fiber slurry.

[0010] Chitosan-modified aramid insulating paper is obtained by using the mixed aramid fiber slurry and a pre-defined papermaking method.

[0011] This invention discloses a method for preparing aramid insulating paper. By incorporating chitosan molecules during the preparation process, chitosan-modified aramid fiber is formed, serving as a marker for the chitosan-modified aramid insulating paper. Besides serving as a marker, the chitosan is rich in hydroxyl and amino groups, while the aramid fiber is rich in carboxyl groups. Hydrogen bonds can form between the two, which is beneficial for improving the bonding force between the aramid fiber and the chopped fiber, thereby enhancing the mechanical properties of the insulating paper. In addition to improving mechanical properties, when local overheating occurs, the chitosan groups on the chitosan-modified aramid fiber decompose to generate small-molecule methanol. The local heating result can be determined by detecting the methanol content. Therefore, the aramid insulating paper prepared using this invention is no longer affected by external factors and limitations in application during local overheating detection, greatly improving the accuracy of local overheating detection.

[0012] Furthermore, the aramid chromatography fiber dispersion is obtained by adding meta-aramid precipitated fibers to a dimethyl sulfoxide solution and then ultrasonically stirring, specifically:

[0013] The meta-aramid precipitated fiber and dimethyl sulfoxide were mixed in a predetermined ratio to obtain a mixed solution;

[0014] The mixed solution was ultrasonically stirred while a preset amount of potassium hydroxide was added, and ultrasonic stirring was continued for a preset time to obtain an aramid chromatographic fiber dispersion.

[0015] The mass ratio of the meta-aramid precipitated fiber to the volume ratio of dimethyl sulfoxide is 1:100.

[0016] Furthermore, the chitosan aqueous solution is prepared by mixing chitosan and water in a preset ratio; wherein the mass ratio of chitosan to water is 1:1000.

[0017] Furthermore, the beating degree of the meta-aramid short-cut fibers in the first dispersion is 40°SR to 55°SR, and the mass concentration in the first dispersion is 0.3% to 1.0%.

[0018] The freeness of the meta-aramid precipitated fiber in the second dispersion is 25°SR to 35°SR, and its mass concentration in the second dispersion is 1.5% to 2.5%.

[0019] The chitosan-modified aramid chromatography fiber in the third dispersion has a freeness of 20°SR to 40°SR and a mass concentration of 1.5% to 2.5% in the third dispersion.

[0020] Furthermore, the dispersant sodium polyacrylate used in the dispersion treatment of the first dispersion, the second dispersion and the third dispersion has a molecular weight of 2000 to 5000.

[0021] Furthermore, the preset ratio is specifically as follows: the oven-dry mass ratio of the meta-aramid chopped fibers to the total of the meta-aramid precipitated fibers and chitosan aramid chromatographic fibers is 1:1 to 1:3; the oven-dry mass ratio of the meta-aramid precipitated fibers to the chitosan aramid chromatographic fibers is 1:1 to 1:2.

[0022] The stirring speed for mixing the first dispersion, the second dispersion, and the third dispersion in a preset ratio is specifically 3000 r / min to 5000 r / min.

[0023] Furthermore, the process of obtaining chitosan-modified aramid insulating paper based on the mixed aramid fiber slurry and a predetermined papermaking method specifically involves:

[0024] Chitosan-modified aramid insulating paper is obtained by injecting mixed aramid fiber slurry into a paper forming machine and then sequentially dehydrating and hot-pressing it.

[0025] Furthermore, the mass concentration of the mixed aramid fiber slurry is 0.10% to 0.20%;

[0026] The hot pressing conditions are: temperature of 200℃~270℃; pressure of 6.0MPa~10.0MPa; and time of 0.5h~1h.

[0027] This invention also proposes an aramid insulating paper preparation system, comprising: a primary processing module, a secondary processing module, a tertiary processing module, a quaternary processing module, and a quinary processing module;

[0028] The primary processing module is used to add the chitosan aqueous solution to the aramid chromatographic fiber dispersion and perform ultrasonic stirring to obtain an aramid chromatographic fiber-chitosan suspension; wherein, the aramid chromatographic fiber dispersion is obtained by adding meta-aramid precipitated fibers to a dimethyl sulfoxide solution and performing ultrasonic stirring.

[0029] The secondary processing module is used to add the aramid chromatography fiber-chitosan suspension to distilled water and sequentially perform filtration, washing and drying to obtain chitosan-modified aramid chromatography fiber;

[0030] The three-stage processing module is used to sequentially pulp and disperse meta-aramid short-cut fibers, meta-aramid precipitated fibers, and chitosan-modified aramid chromatographic fibers to obtain a first dispersion, a second dispersion, and a third dispersion.

[0031] The four-stage processing module is used to mix and stir the first dispersion, the second dispersion and the third dispersion in a preset ratio to obtain a mixed aramid fiber slurry.

[0032] The five-stage processing module is used to obtain chitosan-modified aramid insulating paper according to the mixed aramid fiber slurry and the preset papermaking method.

[0033] This invention proposes an aramid insulating paper preparation system. This system converts chitosan into chitosan-modified aramid chromatographic fibers and then presses the fibers into paper using a preparation process. Chitosan is rich in hydroxyl and amino groups, while the aramid chromatographic fibers are rich in carboxyl groups. Hydrogen bonds can form between the two, improving the mechanical properties of the chitosan-modified aramid insulating paper. Furthermore, chitosan decomposes into small-molecule methanol at excessively high temperatures, which can be used to monitor localized overheating in transformer windings. Because the decomposition product is singular, it saves detection time and steps, greatly improving the accuracy of localized overheating detection in transformer windings by eliminating the limitations of cumbersome procedures and materials.

[0034] Furthermore, the primary processing module is used to obtain an aramid chromatography fiber-chitosan suspension by adding the chitosan aqueous solution to the aramid chromatography fiber dispersion and performing ultrasonic stirring; wherein the aramid chromatography fiber dispersion is obtained by adding meta-aramid precipitated fibers to a dimethyl sulfoxide solution and performing ultrasonic stirring, and further includes:

[0035] Mixing unit and ultrasonic stirring unit;

[0036] The mixing unit is used to mix meta-aramid precipitated fibers and dimethyl sulfoxide in a preset ratio to obtain a mixed solution;

[0037] The ultrasonic stirring unit is used to ultrasonically stir the mixed solution, while adding a preset amount of potassium hydroxide and continuing ultrasonic stirring for a preset time to obtain an aramid chromatography fiber dispersion.

[0038] The mass ratio of the meta-aramid precipitated fiber to the volume ratio of dimethyl sulfoxide is 1:100. Attached Figure Description

[0039] Figure 1 This is a schematic flowchart of a method for preparing aramid insulating paper according to a certain embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the module structure of an aramid insulating paper preparation system according to a certain embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the primary processing module structure of an aramid insulating paper preparation system proposed in an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of the methanol content detection experimental results curve of a method for preparing aramid insulating paper according to a certain embodiment of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0044] In the power industry, transformers are indispensable equipment. Their normal operation is crucial for the stable operation of the power system. However, due to various factors, localized overheating of the insulation paper in transformers has always been a challenge. The technical solution proposed in this invention, by adding markers during the insulation paper preparation process, can promptly and accurately identify localized overheating of the insulation paper in transformers, thereby avoiding potential faults and accidents. Therefore, in the power industry, the technical solution proposed in this embodiment can improve the safety and reliability of transformers and reduce maintenance and replacement costs, attracting widespread attention and application.

[0045] In the transformer manufacturing industry, the technical solution proposed in this embodiment can be applied to the transformer manufacturing process. By adding markers to the insulating paper, localized overheating can be monitored. This is crucial for improving quality control in transformer manufacturing. Through the technical solution proposed in this embodiment, manufacturers can promptly detect and resolve issues related to localized overheating of the insulating paper, improving the quality and performance of transformers and meeting market demands for high-quality transformers.

[0046] Meanwhile, the technical solution proposed in this embodiment also has potential applications in the field of related insulation materials. Insulation materials are a very important component of power equipment, playing a crucial role in the performance and lifespan of the equipment. The technical solution proposed in this embodiment can monitor local overheating by adding markers to the insulation material, providing a new means for quality control of insulation materials. Therefore, in the field of related insulation materials, the technical solution proposed in this embodiment can help manufacturers improve product quality and reliability, meeting the market demand for high-performance insulation materials.

[0047] It is worth mentioning that the specific parameters such as sample mass, concentration and ratio used in the embodiments of the present invention are just one example of the feasible solution of the present invention, and no other specific limitations are made. They will not be repeated below.

[0048] Example 1

[0049] See Figure 1 , Figure 1 This is a schematic flowchart illustrating the steps of a method for preparing aramid insulating paper according to a certain embodiment of the present invention. Figure 1 As shown, this invention proposes a method for preparing aramid insulating paper, including steps 101 to 105, the specific details of which are as follows:

[0050] Step 101: An aramid-chitosan suspension is obtained by adding the chitosan aqueous solution to the aramid chromatographic fiber dispersion and ultrasonically stirring it; wherein the aramid chromatographic fiber dispersion is obtained by adding meta-aramid precipitated fibers to a dimethyl sulfoxide solution and ultrasonically stirring it.

[0051] As an example of this embodiment, meta-aramid precipitated fibers and dimethyl sulfoxide are mixed in a preset ratio to obtain a mixed solution;

[0052] The mixed solution was ultrasonically stirred while a preset amount of potassium hydroxide was added, and ultrasonic stirring was continued for a preset time to obtain an aramid chromatographic fiber dispersion.

[0053] The mass ratio of the meta-aramid precipitated fiber to the volume ratio of dimethyl sulfoxide is 1:100.

[0054] The chitosan aqueous solution is prepared by mixing chitosan and water in a preset ratio; wherein the mass ratio of chitosan to water is 1:1000.

[0055] As another example of this embodiment, a specific feasible implementation is as follows: 5g-10g of meta-aramid precipitated fibers are added to a mixed solution of dimethyl sulfoxide and water, wherein the volume of dimethyl sulfoxide is 500mL-1000mL and the volume of water is 10mL-30mL. The mixture is stirred under ultrasonic conditions, and then 5g-10g of potassium hydroxide is added. The mixture is then stirred ultrasonically for 12-24 hours to obtain an aramid chromatographic fiber dispersion. Next, 1g-5g of chitosan is added to 1L-5L of water to prepare a chitosan aqueous solution. Under ultrasonic stirring, the chitosan aqueous solution is added dropwise to the aramid chromatographic fiber dispersion, and the mixture is stirred ultrasonically for 2-5 hours to obtain an aramid chromatographic fiber-chitosan suspension.

[0056] Step 102: The aramid chromatography fiber-chitosan suspension is added to distilled water and then filtered, washed and dried sequentially to obtain chitosan-modified aramid chromatography fiber.

[0057] As an example of this embodiment, an aramid chromatography fiber-chitosan suspension is added to distilled water to form a colloid, then filtered and washed with distilled water until the filtrate is neutral, and then vacuum dried at room temperature to obtain chitosan-modified aramid chromatography fiber.

[0058] Step 103: Meta-aramid short-cut fibers, meta-aramid precipitated fibers, and chitosan-modified aramid chromatographic fibers are sequentially pulped and dispersed to obtain a first dispersion, a second dispersion, and a third dispersion.

[0059] As an example of this embodiment, meta-aramid chopped fibers, meta-aramid precipitated fibers, and chitosan-modified aramid chromatographic fibers are respectively pulped and dispersed, and dispersants are added to prepare dispersion suspensions for later use. The degree of freeing of the meta-aramid chopped fibers is 40°SR to 55°SR, and the mass concentration in the dispersion is 0.3% to 1.0%. The degree of freeing of the meta-aramid precipitated fibers is 25°SR to 35°SR, and the mass concentration in the dispersion is 1.5% to 2.5%. The degree of freeing of the chitosan-modified aramid chromatographic fibers is 20°SR to 40°SR, and the mass concentration in the dispersion is 1.5% to 2.5%. The sodium polyacrylate dispersant used in the dispersion treatment of the first, second, and third dispersions has a molecular weight of 2000 to 5000.

[0060] Step 104: Mix and stir the first dispersion, the second dispersion and the third dispersion in a preset ratio to obtain a mixed aramid fiber slurry;

[0061] As an example of this embodiment, under stirring conditions, the dispersions of meta-aramid chopped fibers, meta-aramid precipitated fibers, and chitosan aramid chromatographic fibers are uniformly mixed in a certain ratio to obtain a mixed aramid fiber slurry. The oven-dry mass ratio of the meta-aramid chopped fibers to the total amount of the meta-aramid precipitated fibers and chitosan aramid chromatographic fibers is 1:1 to 1:3; the oven-dry mass ratio of the meta-aramid precipitated fibers to the chitosan aramid chromatographic fibers is 1:1 to 1:2. The stirring speed for mixing the first dispersion, the second dispersion, and the third dispersion in a preset ratio is specifically 3000 r / min to 5000 r / min.

[0062] Step 105: According to the mixed aramid fiber slurry and the preset papermaking method, chitosan modified aramid insulating paper is obtained.

[0063] As an example of this embodiment, the obtained mixed slurry is injected into a paper forming machine for dehydration and forming, and then hot-pressed at high temperature to obtain a special aramid insulating paper (chitosan modified aramid insulating paper).

[0064] As another example of this embodiment, the mass concentration of the mixed aramid fiber slurry is 0.10% to 0.20%; the paper forming device is a technical means that can be implemented by existing technologies such as an inclined wire ultra-low concentration forming device, which will not be described in detail below; the high-temperature hot pressing conditions are: temperature of 200℃ to 270℃; pressure of 6.0MPa to 10.0MPa; time of 0.5h to 1h; the chitosan modified aramid insulating paper can be used in transformer windings and is immersed in insulating oil during application.

[0065] As another example of this embodiment, the specific process for preparing aramid insulating paper is as follows:

[0066] (1) Preparation of chitosan-modified aramid chromatography fibers:

[0067] A: Add 5g of meta-aramid precipitated fiber to a mixed solution of dimethyl sulfoxide and water, wherein the volume of dimethyl sulfoxide is 500mL and the volume of water is 10mL. Stir under ultrasonic conditions, then add 5g of potassium hydroxide and continue ultrasonic stirring for 12 hours to obtain an aramid chromatographic fiber dispersion.

[0068] B: Add 1g of chitosan to 1L of water to prepare a chitosan aqueous solution.

[0069] C: Under ultrasonic stirring, chitosan aqueous solution was added dropwise to aramid chromatographic fiber dispersion, and ultrasonic stirring was continued for 2 hours to obtain aramid chromatographic fiber-chitosan suspension.

[0070] D: Add the aramid chromatography fiber-chitosan suspension to distilled water to form a colloid, then filter and wash with distilled water until the filtrate is neutral. Dry under vacuum at room temperature to obtain chitosan-modified aramid chromatography fiber.

[0071] (2) Pulping Treatment: The meta-aramid chopped fibers, meta-aramid precipitated fibers, and chitosan-modified aramid chromatographic fibers were pulped and dispersed separately, and dispersants were added to prepare dispersion suspensions for later use. The degree of pulping of the meta-aramid chopped fibers in step (2) was 40°SR; the degree of pulping of the meta-aramid precipitated fibers was 25°SR; and the degree of pulping of the chitosan-modified aramid chromatographic fibers was 20°SR. The dispersant in step (2) was sodium polyacrylate with a molecular weight of 2000. After pulping in step (2), the mass concentration of the meta-aramid chopped fibers in the dispersion was 0.3%, the mass concentration of the meta-aramid precipitated fibers in the dispersion was 1.5%, and the mass concentration of the chitosan-modified aramid chromatographic fibers in the dispersion was 1.5%.

[0072] (3) Preparation of aramid fiber slurry: Under stirring conditions, the dispersions of meta-aramid chopped fibers, meta-aramid precipitated fibers, and chitosan aramid chromatographic fibers obtained in step (2) are uniformly mixed in a certain ratio to obtain a mixed aramid fiber slurry. The oven-dry mass ratio of the meta-aramid chopped fibers to (meta-aramid precipitated fibers + chitosan aramid chromatographic fibers) in step (3) is 1:3, and the oven-dry mass ratio of the meta-aramid precipitated fibers to the chitosan aramid chromatographic fibers is 1:2. The stirring speed in step (3) is 3000 r / min.

[0073] (4) Post-paper processing: The mixed pulp obtained in step (3) is injected into a paper forming machine for dehydration and forming, and then hot-pressed at high temperature to obtain special aramid insulating paper (chitosan modified aramid insulating paper). Among them, the mass concentration of the pulp in the inclined wire ultra-low concentration forming in step (4) is 0.10%; the high temperature hot pressing conditions are: temperature 200℃; pressure 6.0MPa; time 0.5h.

[0074] See Figure 4 , Figure 4 This is a schematic diagram of the methanol content detection experimental results curve for a method of preparing aramid insulating paper according to a certain embodiment of the present invention. Figure 4 As shown, 10g of the prepared chitosan-modified aramid insulating paper was placed in 500mL of insulating oil and aged at 150℃ for 24h. Transformer insulating oil samples were collected, and methanol was detected according to the method in "DL / T2445-2021 Determination of Methanol Content in Operating Transformer Oil by Gas Chromatography-Mass Spectrometry". A standard curve was established, and the methanol content in the transformer insulating oil sample was found to be 165ug / L.

[0075] 10g of aramid insulating paper prepared by existing technology was placed in 500mL of insulating oil and aged at 150℃ for 24h. Transformer insulating oil samples were collected, and the methanol content in the transformer insulating oil samples was determined to be 0ug / L using the standard curve described above and the method in "DL / T2445-2021 Determination of Methanol Content in Operating Transformer Oil by Gas Chromatography-Mass Spectrometry".

[0076] 10g of the prepared chitosan-modified aramid insulating paper was placed in 500mL of insulating oil and aged at 60℃ for 24h. Transformer insulating oil samples were collected and methanol was detected according to the method in "DL / T2445-2021 Determination of Methanol Content in Operating Transformer Oil by Gas Chromatography-Mass Spectrometry". The established standard curve is shown in the figure below. The methanol content in the transformer insulating oil sample was found to be 0ug / L.

[0077] Comparing the experimental results of simulated aging of the prepared chitosan-modified aramid insulating paper at 150℃ for 24 hours and at 60℃ for 24 hours, it can be seen that under overheating conditions (normal transformer operating temperature 60-80℃, 150℃ is considered overheating), the chitosan-aramid chromatography fiber marker will decompose and release specific small molecule methanol. However, under normal operating conditions, the chitosan-aramid chromatography fiber marker will not decompose. Therefore, the marker can be used to monitor overheating conditions.

[0078] The prepared chitosan-modified aramid insulating paper and conventional aramid insulating paper prepared by existing technology (which are completely identical except for the chitosan modification) were tested for thickness, tensile strength, and elongation. The test results are shown in Table 1 below:

[0079] Table 1 Performance test results of chitosan-modified aramid insulating paper and conventional aramid insulating paper

[0080]

[0081]

[0082] The comparison results in Table 1 show that the tensile strength and elongation of chitosan-modified aramid insulating paper are significantly better than those of conventional aramid insulating paper, indicating that the mechanical properties of aramid paper prepared by adding chitosan aramid chromatography fibers are superior to those of aramid paper under the same conditions.

[0083] In summary, the aramid insulating paper preparation method proposed in this invention involves incorporating chitosan molecules during the preparation process to create chitosan-modified aramid fiber layers, which serve as markers for the chitosan-modified aramid insulating paper. Besides serving as markers, the chitosan is rich in hydroxyl and amino groups, while the aramid fibers are rich in carboxyl groups. Hydrogen bonds can form between the two, which is beneficial for improving the bonding force between the aramid fibers and chopped fibers, thereby enhancing the mechanical properties of the insulating paper. In addition to improving mechanical properties, when local overheating occurs, the chitosan groups on the chitosan-modified aramid fibers decompose to generate small-molecule methanol. The local heating result can be determined by detecting the methanol content. Therefore, the aramid insulating paper prepared using this invention is no longer affected by external factors and limitations in its application, greatly improving the accuracy of local overheat detection.

[0084] See Figure 2 , Figure 2 This is a schematic diagram of the module structure of an aramid insulating paper preparation system according to a certain embodiment of the present invention; as shown below. Figure 2 As shown in the figure, an embodiment of the present invention also proposes an aramid insulating paper preparation system, comprising:

[0085] Level 1 processing module 201, Level 2 processing module 202, Level 3 processing module 203, Level 4 processing module 204, and Level 5 processing module 205;

[0086] The primary processing module 201 is used to add the chitosan aqueous solution to the aramid chromatographic fiber dispersion and perform ultrasonic stirring to obtain an aramid chromatographic fiber-chitosan suspension; wherein, the aramid chromatographic fiber dispersion is obtained by adding meta-aramid precipitated fibers to a dimethyl sulfoxide solution and performing ultrasonic stirring.

[0087] As an example of this embodiment, see Figure 3 , Figure 3 This is a schematic diagram of the primary processing module structure of an aramid insulating paper preparation system proposed in an embodiment of the present invention. Figure 3 As shown, the primary processing module 201 is used to obtain an aramid chromatography fiber-chitosan suspension by adding the chitosan aqueous solution to the aramid chromatography fiber dispersion and performing ultrasonic stirring; wherein, the aramid chromatography fiber dispersion is obtained by adding meta-aramid precipitated fibers to a dimethyl sulfoxide solution and performing ultrasonic stirring, and further includes:

[0088] Mixing unit 301 and ultrasonic stirring unit 302;

[0089] The mixing unit 301 is used to mix meta-aramid precipitated fibers and dimethyl sulfoxide in a preset ratio to obtain a mixed solution;

[0090] The ultrasonic stirring unit 302 is used to ultrasonically stir the mixed solution, while adding a preset amount of potassium hydroxide and continuing ultrasonic stirring for a preset time to obtain an aramid chromatographic fiber dispersion; wherein the mass ratio of the meta-aramid precipitated fiber to the volume ratio of dimethyl sulfoxide is 1:100.

[0091] The secondary processing module 202 is used to obtain chitosan-modified aramid chromatography fibers by adding the aramid chromatography fiber-chitosan suspension to distilled water and sequentially filtering, washing and drying.

[0092] The three-stage processing module 203 is used to sequentially pulp and disperse meta-aramid short-cut fibers, meta-aramid precipitated fibers, and chitosan-modified aramid chromatographic fibers to obtain a first dispersion, a second dispersion, and a third dispersion.

[0093] The fourth-level processing module 204 is used to mix and stir the first dispersion, the second dispersion and the third dispersion in a preset ratio to obtain a mixed aramid fiber slurry.

[0094] The five-stage processing module 205 is used to obtain chitosan-modified aramid insulating paper according to the mixed aramid fiber slurry and the preset papermaking method.

[0095] This invention proposes an aramid insulating paper preparation system. This system converts chitosan into chitosan-modified aramid chromatographic fibers and then presses the fibers into paper using a preparation process. Chitosan is rich in hydroxyl and amino groups, while the aramid chromatographic fibers are rich in carboxyl groups. Hydrogen bonds can form between the two, improving the mechanical properties of the chitosan-modified aramid insulating paper. Furthermore, chitosan decomposes into small-molecule methanol at excessively high temperatures, which can be used to monitor localized overheating in transformer windings. Because the decomposition product is singular, it saves detection time and steps, greatly improving the accuracy of localized overheating detection in transformer windings by eliminating the limitations of cumbersome procedures and materials.

[0096] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0097] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0098] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

Claims

1. A method for preparing aramid insulating paper, characterized in that, include: An aramid-chitosan suspension was obtained by adding a chitosan aqueous solution to an aramid chromatographic fiber dispersion and then ultrasonically stirring it. Specifically, the aramid chromatographic fiber dispersion was obtained by adding meta-aramid precipitated fibers to a dimethyl sulfoxide solution and then ultrasonically stirring it. The meta-aramid precipitated fibers and dimethyl sulfoxide were mixed in a predetermined ratio to obtain a mixed solution. The mixed solution was then ultrasonically stirred, and a predetermined amount of potassium hydroxide was added. Ultrasonic stirring was continued for a predetermined time to obtain the aramid chromatographic fiber dispersion. The mass ratio of the meta-aramid precipitated fibers to the volume ratio of dimethyl sulfoxide was 1:

100. By adding the aramid chromatographic fiber-chitosan suspension to distilled water and sequentially filtering, washing, and drying, chitosan-modified aramid chromatographic fibers are obtained. Meta-aramid chopped fibers, meta-aramid precipitated fibers, and chitosan-modified aramid chromatographic fibers are sequentially pulped and dispersed to obtain a first dispersion, a second dispersion, and a third dispersion. The meta-aramid chopped fibers in the first dispersion have a freeness of 40°SR to 55°SR and a mass concentration of 0.3% to 1.0%. The meta-aramid precipitated fibers in the second dispersion have a freeness of 25°SR to 35°SR and a mass concentration of 1.5% to 2.5%. The chitosan-modified aramid chromatographic fibers in the third dispersion have a freeness of 20°SR to 40°SR and a mass concentration of 1.5% to 2.5%. The first dispersion, the second dispersion and the third dispersion are mixed and stirred in a preset ratio to obtain a mixed aramid fiber slurry. Chitosan-modified aramid insulating paper is obtained by using the mixed aramid fiber slurry and a pre-defined papermaking method.

2. The method for preparing aramid insulating paper as described in claim 1, characterized in that, The chitosan aqueous solution is prepared by mixing chitosan and water in a preset ratio; wherein the mass ratio of chitosan to water is 1:1000.

3. The method for preparing aramid insulating paper as described in claim 1, characterized in that, Also includes: The first dispersion, the second dispersion, and the third dispersion are dispersed, wherein the dispersant used is sodium polyacrylate, and the molecular weight of sodium polyacrylate is 2000~5000.

4. The method for preparing aramid insulating paper as described in claim 1, characterized in that, The oven-dry mass ratio of the meta-aramid chopped fibers to the total amount of the meta-aramid precipitated fibers and chitosan-modified aramid chromatographic fibers is 1:1 to 1:3; the oven-dry mass ratio of the meta-aramid precipitated fibers to the chitosan-modified aramid chromatographic fibers is 1:1 to 1:

2. The stirring speed for mixing the first dispersion, the second dispersion, and the third dispersion in a preset ratio is specifically 3000 r / min to 5000 r / min.

5. The method for preparing aramid insulating paper as described in claim 1, characterized in that, The process of obtaining chitosan-modified aramid insulating paper according to the mixed aramid fiber slurry and a predetermined papermaking method specifically involves: Chitosan-modified aramid insulating paper is obtained by injecting mixed aramid fiber slurry into a paper forming machine and then sequentially dehydrating and hot-pressing it.

6. The method for preparing aramid insulating paper as described in claim 5, characterized in that, The mass concentration of the mixed aramid fiber slurry is 0.10%~0.20%; The hot pressing conditions are: temperature of 200℃~270℃; pressure of 6.0MPa~10.0MPa; and time of 0.5h~1h.

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