Preparation method of modified mica insulation material and production process of heat-resistant mica tape

Abstract

The present invention belongs to the technical field of insulating materials and relates to a preparation method of a modified mica insulating material and a production process for heat-resistant mica tape. Hydroxyl polyurethane hybrid mica material is obtained by connecting the NH2 on the surface of silane-modified mica material and the interfacial amino groups between cyclocarbonates, and the material is prepared into calcined mica paper. Starting from polyester film, non-self-adhesive mica tape and self-adhesive mica tape products are obtained respectively through two different preparation processes. First, the polyester film is coated with an adhesive and then compounded with modified calcined mica paper, and then dried, wound up and cut to obtain a non-self-adhesive mica tape product. Second, the back of the polyester film is corona treated, coated with self-adhesive glue and then dried, and then coated with an adhesive after drying and compounded with modified calcined mica paper, and then dried, wound up and cut to obtain a self-adhesive mica tape product. The modified mica tape has excellent insulating properties in a high-temperature environment and can effectively inhibit the aging and decomposition of the mica layer.

Description

Technical Field

[0001] The present invention belongs to the technical field of insulating materials, and mainly relates to the preparation of a mica insulating material, and in particular to a preparation method of a modified mica insulating material and a production process of a heat-resistant mica tape. Background Art

[0002] The voltage level of large-scale high-voltage generators can reach up to 27 kV, and the main insulation thickness can reach up to 6~7 mm. The overall size of the motor is huge, and the safe operation life is required to be as long as several decades. However, during the long-term operation of the motor, the main insulation of the motor will continue to be affected by the synergistic effect of multiple stresses, the most important of which is the combined effect of thermal, electrical, environmental and mechanical stresses, which causes the main insulation performance of the motor to slowly age, and eventually leads to a complete loss of insulation performance, and even possible breakdown. According to research, about 40% of the failures in electric motors or generators are caused by aging of the main insulation. Therefore, the operational reliability and service life of high-voltage motors depend to a large extent on the main insulation condition of the stator winding. The main insulation material of high-voltage motors is mica tape, which is mainly composed of powdered mica paper, reinforcing materials and adhesives. In order to meet the requirements of high voltage levels and large capacities of high-voltage motors, mica tape is also moving towards

[0003] The thermal conductivity is getting higher and the thickness is getting thinner.

[0004] Mica tape is a composite insulating material composed primarily of three components: a dielectric material, a reinforcing material, and an adhesive. The dielectric material primarily utilizes mica. Mica offers high dielectric strength, low loss, high heat resistance, and excellent corona resistance. To date, no alternative has been found for motor insulation. Mica paper offers excellent electrical insulation, low dielectric loss, and good corona resistance, but its strength is very low. Furthermore, mica products are susceptible to decomposition and aging at high temperatures, necessitating further improvements to overcome these issues. Summary of the Invention

[0005] In order to solve the problem in related technologies that mica products are prone to decomposition and aging at high temperatures, the present invention provides a method for preparing a modified mica insulation material and a process for producing a heat-resistant mica tape. The specific operating steps are as follows:

[0006] S1. Take 30-50 g of calcined muscovite with a particle size of 200-800 mesh and stir it with 1-1.5 L of deionized water at a rate of 60-120 rpm for 2-4 h to obtain a calcined muscovite slurry. Then heat it to 60-110 ° C, add 0.5-1 g of titanate coupling agent JN114, and continue stirring for 1-3 h. After activation, put it into an electric constant temperature blower, set the temperature to 60-110 ° C, and dry it for 6-12 h to obtain activated calcined mica. In this step, the surface of the mica is modified by the titanate coupling agent JN114, which can effectively enhance the activation index of the mica, promote the dispersion effect of the mica, and promote further effective modification of the mica material.

[0007] S2, taking 20-30 g of the activated calcined mica in step S1 and 100-200 ml of ethanol-water solution (volume ratio of 1:1), stirring continuously at room temperature for 1-3 h, and after the mixture is evenly mixed, adjusting the pH of the reaction solution to 3-4 with 1.5 mol / L acetic acid solution, then adding 10 g of silane coupling agent KH550, stirring continuously for 12-24 h, raising the reaction temperature to 60-80 ° C and continuing to stir for 3-5 h. After the reaction is complete, the product is cooled to room temperature and filtered, and the filter cake is washed 3-5 times with ethanol-water solution and dried at 60 ° C for 12-24 h to obtain a silane-modified calcined mica material; in this step, the mechanical and electrical properties of the mica material are effectively improved by means of the higher cross-linking density of the organic silicate network in the coupling agent;

[0008] S3. Dissolve 20-30 g of bisphenol A epoxy resin in a mixed solution of 15-30 ml of 2-ethoxyethanol and 5-10 ml of methyl vinyl pyrrolidone, add 0.2-0.5 g of tetraethylammonium bromide and 0.05-0.1 g of anhydrous ZnCl2 while stirring, and after the added substances are completely dissolved, transfer to a high-pressure reactor, then introduce carbon dioxide to purge 2-3 times, and after the gas in the reactor is purged, pressurize it with carbon dioxide to 0.4-0.6 MPa, set the reaction temperature to 100-130 ° C, stir the reaction for 12-24 h, and after the reaction is completed, extract the mixed solution with water-ethyl acetate (volume ratio of 1:3) 3-5 times to obtain a yellow solution of bisphenol A cyclic carbonate;

[0009] S4, take the bisphenol A cyclic carbonate obtained in step S3 and mix it with 5-10 ml of acetone, stir it at 30-40 ° C for 30-60 min, and after it is completely dissolved, add 2-3 ml of isophorone diamine and 0.5-2 ml of 1,8-diazabicyclo[5.4.0]undec-7-ene, reflux and mix at 60-80 ° C for 1-3 h, then add 10-15 g of the silane-modified calcined mica material obtained in step S2, continue stirring for 1-2 h, and after the reaction is complete, dry it at 110 ° C for 12 h and at 60 ° C for 12 h. h, then the dried material is mixed with aluminum nitride and aluminum oxide in a mass ratio of 1:0.1-0.3:0.1-0.3 and ball-milled for 1-2h. After the ball milling is completed, the material is collected to obtain a hydroxyl polyurethane hybrid calcined mica material, that is, a modified mica insulating material; in this step, CO2 is used as a raw material and a non-toxic approach is adopted to prepare the hydroxyl polyurethane hybrid mica material, fully stimulating the synergistic effect of the hydroxyl polyurethane and the silane modification in step S3, utilizing the interfacial amino connection between -NH2 and cyclocarbonate on the surface of the silane-modified mica material, while maintaining charge dissipation, effectively improving the insulation performance and toughness of the material;

[0010] S5. Preparation of modified calcined muscovite paper: pulping: the modified mica insulating material obtained in step S4 is put into a pulping machine and crushed and pulped with high-pressure water at a pressure of 6 MPa. The prepared modified mica pulp is graded and dehydrated with three dewatering screens of 14 mesh, 80 mesh and 200 mesh. The obtained 14-80 mesh coarse pulp and 80-200 mesh fine pulp are put into a pulp storage tank and stored separately for standby use; papermaking: the sizing order of the modified mica coarse pulp and the modified mica fine pulp is regulated, and the first sizing of the modified mica fine pulp, the sizing of the modified mica coarse pulp, and then the second sizing of the mica fine pulp are carried out in sequence, and finally, rotary screen papermaking is carried out, and the prepared modified mica paper is dried to a moisture content of 0.2%-0.5% to obtain modified calcined muscovite paper, wherein the sizing amount of the modified mica fine pulp is the same for the two times, and the mass ratio of the mica coarse pulp to the mica fine pulp during sizing is controlled to be 1-2:1;

[0011] S6. Preparation of non-self-adhesive mica tape: A polyester film (purchased from Henan Dongjue Electric Co., Ltd.) was coated with an adhesive (purchased from Shandong Guohua Chemical Co., Ltd.) and then laminated with modified calcined mica paper under heating and pressure at 100-150°C. The tape was then dried, rolled, and slit to obtain a non-self-adhesive mica tape product.

[0012] S7. Preparation of self-adhesive mica tape: corona-treat the back of the polyester film, apply self-adhesive glue and dry it, apply adhesive and heat-press the modified calcined mica paper at 100-150°C and laminate them, then dry, roll and slit to obtain the self-adhesive mica tape product.

[0013] Preferably: the muscovite particles in step S1 have a size of 400 mesh.

[0014] Preferably, the amount of titanate coupling agent JN114 added in step S1 is 0.7 g.

[0015] Preferably, the amount of activated mica added in step S2 is 20 g.

[0016] Preferably, the carbon dioxide pressure in step S3 is 0.6 MPa.

[0017] Preferably, the amount of isophoronediamine added in step S4 is 2.8 ml.

[0018] Preferably, in step S5, the mold is first heated to 80-110°C, with a pressure of 0.6 MPa for 45 seconds, second heated to 120-150°C, with a pressure of 0.8 MPa for 140 seconds, and third cooled to room temperature at a cooling rate of 10°C / min.

[0019] Preferably, in step S6, the polyester film is coated with an adhesive and then laminated with the modified calcined mica paper under heating and pressure at 100-150°C.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention has excellent breakdown field strength and resistivity at high temperatures.

[0022] 2. The present invention is generally applicable to conductors and main insulation or supporting insulation materials.

[0023] 3. The mica tape of the present invention has good thermal stability and higher safety performance.

[0024] 4. Through a special sizing sequence, the electrical strength and tensile strength of mica paper are enhanced. The fine scales on the surface cover the unevenness of the coarse scales, further enhancing the electrical strength of mica paper and making the surface more flat and smooth. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 The figure is a process flow chart for preparing mica tape products according to the present invention.

[0027] Figure 2This is a graph showing the tensile strength of the modified calcined mica paper prepared in the present invention.

[0028] Figure 3 This is a diagram showing the tear strength of the modified calcined mica paper prepared in the present invention.

[0029] Figure 4 Thermal conductivity diagram of the self-adhesive mica tapes prepared in Examples 1, 2 and 4 and Comparative Examples 2, 3, 6 and 7 of the present invention after aging.

[0030] Figure 5 The breakdown field strength diagram of the self-adhesive mica tapes prepared in Examples 1, 2 and 4 and Comparative Examples 2, 3, 6 and 7 of the present invention after aging. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] The embodiment can obtain two products, one: non-self-adhesive mica tape product; the other: self-adhesive mica tape product; product preparation flow chart see Figure 1 shown.

[0033] Example 1

[0034] S1. Take 30 g of calcined muscovite with a particle size of 200 mesh and 1 L of deionized water and stir at a rate of 60 rpm for 2 h to obtain a calcined muscovite slurry. Then heat it to 60°C, add 0.5 g of titanate coupling agent JN114, and continue stirring for 1 h. After activation, put it into an electric constant temperature blower, set the temperature to 60°C, and dry it for 6 h to obtain activated calcined mica;

[0035] S2, taking 20 g of the activated calcined mica in step S1 and mixing it with 100 ml of ethanol-water solution (volume ratio of 1:1), stirring continuously at room temperature for 1 hour, and after the mixture is evenly mixed, using 1.5 mol / L acetic acid solution to adjust the pH of the reaction solution to 3, then adding 10 g of silane coupling agent KH550, stirring continuously for 12 hours, raising the reaction temperature to 60 ° C and continuing to stir for 3 hours. After the reaction is complete, the product is cooled to room temperature and filtered, and the filter cake is washed 3 times with ethanol-water solution and dried at 60 ° C for 12 hours to obtain a silane-modified calcined mica material;

[0036] S3. Dissolve 20 g of bisphenol A epoxy resin in a mixed solution of 15 ml of 2-ethoxyethanol and 5 ml of methyl vinyl pyrrolidone, add 0.2 g of tetraethylammonium bromide and 0.05 g of anhydrous ZnCl2 while stirring, and after the added substances are completely dissolved, transfer to a high-pressure reactor, then introduce carbon dioxide to purge twice. After the gas in the reactor is purged, pressurize it with carbon dioxide to 0.4 MPa, set the reaction temperature to 100 ° C, and stir the reaction for 12 h. After the reaction is completed, extract the mixed solution three times with water-ethyl acetate (volume ratio of 1:3). The final yellow solution obtained is bisphenol A cyclocarbonate;

[0037] S4. Mix the bisphenol A cyclic carbonate obtained in step S3 with 5 ml of acetone, stir at 30° C. for 30 min, and after complete dissolution, add 2 ml of isophorone diamine and 0.5 ml of 1,8-diazabicyclo[5.4.0]undec-7-ene, reflux and mix at 60° C. for 1 h, then add 10 g of the silane-modified calcined mica material obtained in step S2, continue stirring for 1 h, and after the reaction is complete, dry it at 110° C. for 12 h and at 60° C. for 12 h, then mix the dried material with aluminum nitride and aluminum oxide in a mass ratio of 1:0.2:0.1 and ball mill for 1.5 h. After ball milling, collect the material to obtain a hydroxyl polyurethane hybrid calcined mica material;

[0038] S5. Preparation of modified calcined muscovite paper: pulping: the modified mica insulating material obtained in step S4 is put into a pulping machine and crushed and pulped with high-pressure water at a pressure of 6 MPa. The prepared modified mica pulp is graded and dehydrated with three dewatering screens of 14 mesh, 80 mesh and 200 mesh to obtain 14-80 mesh coarse pulp and 80-200 mesh fine pulp, which are then put into a pulp storage tank for storage and standby use; papermaking: the sizing order of the modified mica coarse pulp and the modified mica fine pulp is regulated, and the first sizing of the modified mica fine pulp, the sizing of the modified mica coarse pulp, and the second sizing of the mica fine pulp are carried out in sequence, and finally, rotary papermaking is carried out, and the prepared modified mica paper is dried to a moisture content of 0.2% to obtain modified calcined muscovite paper, wherein the sizing amount of the modified mica fine pulp is the same for the two times, and the mass ratio of the mica coarse pulp to the mica fine pulp during sizing is controlled to be 1.5:1;

[0039] S6. Preparation of non-self-adhesive mica tape: coating a polyester film with an adhesive and laminating the film with the modified calcined mica paper obtained in step S5 under heating and pressure at 100° C., followed by drying, winding, and slitting to obtain a non-self-adhesive mica tape product;

[0040] S7. Preparation of self-adhesive mica tape: corona-treating the back of the polyester film, coating it with self-adhesive glue, and then drying it. After drying, coating it with adhesive and compounding it with the modified calcined mica paper obtained in step S5 under heating and pressurization at 100° C., followed by drying, winding, and slitting to obtain a self-adhesive mica tape product.

[0041] Comparative Example 1: Except that titanate coupling agent JN114 is not used for activation in step S1, the rest are the same as Example 1.

[0042] Comparative Example 2: Except that the silane coupling agent KH550 is not added in step S2, the rest are the same as Example 1.

[0043] Example 2

[0044] S1. Take 50 g of calcined muscovite with a particle size of 800 mesh and stir it with 1.5 L of deionized water at a rate of 120 rpm for 4 h to obtain a calcined muscovite slurry. Then heat it to 110 ° C, add 1 g of titanate coupling agent JN114, and continue stirring for 3 h. After activation, put it into an electric constant temperature blower, set the temperature to 110 ° C, and dry it for 12 h to obtain activated calcined mica;

[0045] S2, taking 30 g of the activated calcined mica in step S1 and mixing it with 200 ml of ethanol-water solution (volume ratio of 1:1), stirring continuously at room temperature for 3 h, and after it is evenly mixed, using 1.5 mol / L acetic acid solution to adjust the pH of the reaction solution to 4, then adding 10 g of silane coupling agent KH550, stirring continuously for 24 h, raising the reaction temperature to 80 ° C and continuing to stir for 5 h. After the reaction is complete, the product is cooled to room temperature and filtered, and the filter cake is washed 5 times with ethanol-water solution and dried at 60 ° C for 24 h to obtain a silane-modified calcined mica material;

[0046] S3. Dissolve 24 g of bisphenol A epoxy resin in a mixed solution of 30 ml of 2-ethoxyethanol and 10 ml of methyl vinyl pyrrolidone, add 0.5 g of tetraethylammonium bromide and 0.1 g of anhydrous ZnCl2 while stirring, and transfer the added substances to a high-pressure reactor after they are completely dissolved. Then, introduce carbon dioxide to purge the reactor three times. After the gas in the reactor is purged, pressurize it with carbon dioxide to 0.6 MPa, set the reaction temperature to 130 ° C, and stir the reaction for 24 h. After the reaction is completed, extract the mixed solution five times with water-ethyl acetate (volume ratio of 1:3). The final yellow solution obtained is bisphenol A cyclocarbonate;

[0047] S4. Mix the bisphenol A cyclic carbonate obtained in step S3 with 7 ml of acetone, stir at 40° C. for 60 min, and after complete dissolution, add 3 ml of isophorone diamine and 2 ml of 1,8-diazabicyclo[5.4.0]undec-7-ene, reflux and mix at 80° C. for 3 h, then add 15 g of the silane-modified calcined mica material obtained in step S2, continue stirring for 2 h, and after the reaction is complete, dry it at 110° C. for 12 h and at 60° C. for 12 h, then mix the dried material with aluminum nitride and aluminum oxide in a mass ratio of 1:0.1:0.2 and ball mill for 2 h. After ball milling, collect the material to obtain a hydroxyl polyurethane hybrid calcined mica material;

[0048] S5. Preparation of modified calcined muscovite paper: pulping: the modified mica insulating material obtained in step S4 is put into a pulping machine and crushed and pulped with high-pressure water at a pressure of 6 MPa. The prepared modified mica pulp is graded and dehydrated with three dewatering screens of 14 mesh, 80 mesh and 200 mesh to obtain 14-80 mesh coarse pulp and 80-200 mesh fine pulp, which are then put into pulp storage tanks for storage and standby use; papermaking: the sizing order of the modified mica coarse pulp and the modified mica fine pulp is regulated, and the first sizing of the modified mica fine pulp, the sizing of the modified mica coarse pulp, and the second sizing of the mica fine pulp are carried out in sequence, and finally, rotary screen papermaking is carried out, and the prepared modified mica paper is dried to a moisture content of 0.5% to obtain modified calcined muscovite paper, wherein the sizing amount of the modified mica fine pulp is the same for the two times, and the mass ratio of the mica coarse pulp to the mica fine pulp during sizing is controlled to be 2:1;

[0049] S6. Preparation of non-self-adhesive mica tape: coating a polyester film with an adhesive and laminating the tape with the modified calcined mica paper obtained in step S5 under heating and pressure at 150° C., followed by drying, winding, and slitting to obtain a non-self-adhesive mica tape product;

[0050] S7. Preparation of self-adhesive mica tape: corona-treating the back of the polyester film, coating it with self-adhesive glue, and then drying it. After drying, coating it with adhesive and compounding it with the modified calcined mica paper obtained in step S5 under heating and pressurization at 150°C. After drying, winding, and slitting, a self-adhesive mica tape product is obtained.

[0051] Comparative Example 3: Except that bisphenol A cyclocarbonate is not used to modify the calcined muscovite in step S4, the rest is the same as Example 2.

[0052] Example 3

[0053] S1. Take 40 g of calcined muscovite with a particle size of 500 mesh and stir it with 1.25 L of deionized water at a rate of 100 rpm for 3 h to obtain a calcined muscovite slurry. Then, heat it to 120 ° C, add 0.5-1 g of titanate coupling agent JN114, and continue stirring for 2 h. After activation, place it in an electric constant temperature blower, set the temperature to 100 ° C, and dry it for 10 h to obtain activated calcined mica;

[0054] S2, taking 25 g of the activated calcined mica in step S1 and mixing it with 150 ml of ethanol-water solution (volume ratio of 1:1), stirring continuously at room temperature for 2 h, and after it is evenly mixed, using 1.5 mol / L acetic acid solution to adjust the pH of the reaction solution to 3.5, then adding 10 g of silane coupling agent KH550, stirring continuously for 18 h, raising the reaction temperature to 70 ° C and continuing to stir for 4 h. After the reaction is complete, the product is cooled to room temperature and filtered, and the filter cake is washed 4 times with ethanol-water solution and dried at 60 ° C for 18 h to obtain a silane-modified calcined mica material;

[0055] S3. Dissolve 25 g of bisphenol A epoxy resin in a mixed solution of 20 ml of 2-ethoxyethanol and 7 ml of methyl vinyl pyrrolidone, add 0.3 g of tetraethylammonium bromide and 0.06 g of anhydrous ZnCl2 while stirring, and after the added substances are completely dissolved, transfer to a high-pressure reactor, then introduce carbon dioxide to purge twice. After the gas in the reactor is purged, pressurize it with carbon dioxide to 0.5 MPa, set the reaction temperature to 120 ° C, and stir the reaction for 18 h. After the reaction is completed, extract the mixed solution four times with water-ethyl acetate (volume ratio of 1:3). The final yellow solution obtained is bisphenol A cyclic carbonate;

[0056] S4. Mix the bisphenol A cyclic carbonate obtained in step S3 with 7 ml of acetone, stir at 35° C. for 35 min, and after complete dissolution, add 2 ml of isophorone diamine and 0.8 ml of 1,8-diazabicyclo[5.4.0]undec-7-ene, reflux and mix at 70° C. for 2 h, then add 14 g of the silane-modified calcined mica material obtained in step S2, continue stirring for 1 h, and after the reaction is complete, dry it at 110° C. for 12 h and at 60° C. for 12 h, then mix the dried material with aluminum nitride and aluminum oxide in a mass ratio of 1:0.2:0.3 and ball mill for 1 h. After ball milling, collect the material to obtain a hydroxyl polyurethane hybrid calcined mica material;

[0057] S5. Preparation of modified calcined muscovite paper: pulping: the modified mica insulating material obtained in step S4 is put into a pulping machine and crushed and pulped with high-pressure water at a pressure of 6 MPa. The prepared modified mica pulp is graded and dehydrated with three dewatering screens of 14 mesh, 80 mesh and 200 mesh to obtain 14-80 mesh coarse pulp and 80-200 mesh fine pulp, which are then put into pulp storage tanks for storage and standby use; papermaking: the sizing order of the modified mica coarse pulp and the modified mica fine pulp is regulated, and the first sizing of the modified mica fine pulp, the sizing of the modified mica coarse pulp, and the second sizing of the mica fine pulp are carried out in sequence, and finally, rotary screen papermaking is carried out, and the prepared modified mica paper is dried to a moisture content of 0.3% to obtain modified calcined muscovite paper, wherein the sizing amount of the modified mica fine pulp is the same for the two times, and the mass ratio of the mica coarse pulp to the mica fine pulp during sizing is controlled to be 1.7:1;

[0058] S6. Preparation of non-self-adhesive mica tape: coating a polyester film with an adhesive and laminating it with modified calcined mica paper under heating and pressure at 120° C., followed by drying, winding, and slitting to obtain a non-self-adhesive mica tape product;

[0059] S7. Preparation of self-adhesive mica tape: corona-treat the back of the polyester film, apply self-adhesive glue and dry it, apply adhesive after drying, heat and pressurize the modified calcined mica paper at 120°C, and then dry, roll up and slit to obtain the self-adhesive mica tape product.

[0060] Comparative Example 4: Except that coarse pulp is used for sizing in step S5, the rest is the same as Example 3.

[0061] Comparative Example 5: Except that fine pulp is used for sizing in step S5, the rest is the same as Example 3.

[0062] Example 4

[0063] S1. Take 33 g of calcined muscovite with a particle size of 230 mesh and stir it with 1.3 L of deionized water at a rate of 110 rpm for 2.5 h to obtain a calcined muscovite slurry. Then, heat it to 90 ° C, add 0.9 g of titanate coupling agent JN114, and continue stirring for 1.5 h. After activation, place it in an electric constant temperature blower, set the temperature to 90 ° C, and dry it for 9 h to obtain activated calcined mica;

[0064] S2, taking 23 g of the activated calcined mica in step S1 and mixing it with 130 ml of ethanol-water solution (volume ratio of 1:1), stirring continuously at room temperature for 3 h, and after it is evenly mixed, using 1.5 mol / L acetic acid solution to adjust the pH of the reaction solution to 3.5, then adding 10 g of silane coupling agent KH550, stirring continuously for 16 h, raising the reaction temperature to 65 ° C and continuing to stir for 3.5 h. After the reaction is complete, the product is cooled to room temperature and filtered, and the filter cake is washed 3.5 times with ethanol-water solution and dried at 60 ° C for 16 h to obtain a silane-modified calcined mica material;

[0065] S3. Dissolve 23 g of bisphenol A epoxy resin in a mixed solution of 25 ml of 2-ethoxyethanol and 9 ml of methyl vinyl pyrrolidone, and add 0.37 g of tetraethylammonium bromide and 0.08 g of anhydrous ZnCl2 while stirring. After the added substances are completely dissolved, transfer them to a high-pressure reactor, then introduce carbon dioxide to purge twice. After the gas in the reactor is purged, pressurize it with carbon dioxide to 0.45 MPa, set the reaction temperature to 110 ° C, and stir the reaction for 16 hours. After the reaction is completed, extract the mixed solution four times with water-ethyl acetate (volume ratio of 1:3). The final yellow solution obtained is bisphenol A cyclocarbonate;

[0066] S4. Mix the bisphenol A cyclic carbonate obtained in step S3 with 7 ml of acetone, stir at 37° C. for 55 min, and after complete dissolution, add 2 ml of isophorone diamine and 1.6 ml of 1,8-diazabicyclo[5.4.0]undec-7-ene, reflux and mix at 65° C. for 2 h, then add 13 g of the silane-modified calcined mica material obtained in step S2, continue stirring for 1 h, and after the reaction is complete, dry it at 110° C. for 12 h and at 60° C. for 12 h, then mix the dried material with aluminum nitride and aluminum oxide in a mass ratio of 1:0.1:0.3 and ball mill for 1 h. After ball milling, collect the material to obtain a hydroxyl polyurethane hybrid calcined mica material;

[0067] S5. Preparation of modified calcined muscovite paper: pulping: the modified mica insulating material obtained in step S4 is put into a pulping machine and crushed and pulped with high-pressure water at a pressure of 6 MPa. The prepared modified mica pulp is graded and dehydrated with three dewatering screens of 14 mesh, 80 mesh and 200 mesh to obtain 14-80 mesh coarse pulp and 80-200 mesh fine pulp, which are then put into pulp storage tanks for storage and standby use; papermaking: the sizing order of the modified mica coarse pulp and the modified mica fine pulp is regulated, and the first sizing of the modified mica fine pulp, the sizing of the modified mica coarse pulp, and the second sizing of the mica fine pulp are carried out in sequence, and finally, rotary screen papermaking is carried out, and the prepared modified mica paper is dried to a moisture content of 0.4% to obtain modified calcined muscovite paper, wherein the sizing amount of the modified mica fine pulp is the same for the two times, and the mass ratio of the mica coarse pulp to the mica fine pulp during sizing is controlled to be 1.8:1;

[0068] S6. Preparation of non-self-adhesive mica tape: coating a polyester film with an adhesive and laminating it with modified calcined mica paper under heating and pressure at 150° C., followed by drying, winding, and slitting to obtain a non-self-adhesive mica tape product;

[0069] S7. Preparation of self-adhesive mica tape: corona-treat the back of the polyester film, apply self-adhesive glue and dry it, apply adhesive after drying, heat and pressurize the modified calcined mica paper at 150°C, and then dry, roll up and slit to obtain the self-adhesive mica tape product.

[0070] Comparative Example 6: Except that aluminum nitride is not added in step S4, the rest is the same as Example 4.

[0071] Comparative Example 7: Except that alumina is not added in step S4, the rest is the same as Example 4.

[0072] Test method: The mechanical properties of the modified calcined mica paper obtained in Examples 1-4, Comparative Example 1, Comparative Example 4, and Comparative Example 5 were tested. The method is as follows:

[0073] Tensile strength test: Tensile strength test usually refers to stretching a material until it breaks to measure the maximum stress it can withstand, thereby evaluating the mechanical properties of the material. First, cut or form a sample of a specific size according to the test standard, usually in the shape of a strip or dog bone. Mount the sample on a universal material testing machine, making sure that the clamps fix both ends of the sample, and then start stretching the sample until it breaks, and record the stress (force divided by the original cross-sectional area) and strain (elongation divided by the original length) of the sample. The maximum stress that a material can withstand during stretching is usually measured in Pascals (Pa) or Megapascals (MPa). The calculation formula is as follows: Tensile strength ( σ )=F / A0, where F is the maximum force the sample can withstand at fracture, in Newtons; A0 is the original cross-sectional area of ​​the sample (square centimeters, cm²).

[0074] Tear strength test: Cut the material into samples of a specific size, usually rectangular or circular. Fix one side of the sample in the upper fixture of the tear tester, leaving a portion of the other side for tearing. Apply a gradually increasing force perpendicular to the edge of the sample to simulate the tearing process. Continue to increase the load until the sample tears. Record the maximum load during the tearing process and the sample size. Tear strength = F max / L, where Fmax is the maximum load recorded when the sample was torn, in N; L is the length of the torn portion of the sample, in cm. The test results are shown in Table 1.

[0075] The thermal conductivity, volume resistivity and breakdown field strength of the non-self-adhesive mica tape products and the self-adhesive mica tape products obtained in Examples 1-4 and Comparative Examples 1-7 were tested as follows:

[0076] Thermal conductivity measurement: Thermal conductivity is a critical property of mica tape. Improving its performance is crucial for improving motor performance and reducing the temperature rise of motor windings. This thermal conductivity test was conducted using an LFA447 Nanoflash laser flash thermal conductivity analyzer manufactured by Netzsch Geratebau GmbH in Germany. The longitudinal thermal conductivity of the mica tape was measured.

[0077] The thermal conductivity is given by the formula: l =a ´ C p ´ r , where: α is the thermal diffusivity, C p is the specific heat capacity, and ρ is the density of the film sample.

[0078] Volume resistivity measurement: Volume resistivity refers to the ratio of the DC voltage applied to the two surfaces of the insulating material per unit volume to the steady-state current passing through the insulating material, expressed as ρ v =R v · A / h Indicates that ρ v Refers to volume resistivity, unit is Ω·cm; R v Refers to volume resistance, unit is Ω; A Refers to the effective area of ​​the measuring electrode, in cm 2 , h Refers to the average thickness of the sample, in cm.

[0079] Breakdown field strength measurements were performed using a ZJC-KV instrument manufactured by Beijing AVIC Times Instruments Co., Ltd. The tests were conducted in air at a voltage ramp rate of 0.2 kV / s at the power frequency. The breakdown voltage (kV) was obtained by dividing it by the paper thickness to obtain the breakdown strength (kV / mm). The breakdown strength was calculated using the formula E=U / d, where E is the breakdown strength (kV / mm); U is the breakdown voltage (kV); and d is the paper thickness (mm). The test results are shown in Tables 2 and 3.

[0080] Table 1 Properties of modified calcined mica paper

[0081]

[0082] Table 2 Non-self-adhesive mica tape product properties

[0083]

[0084] Table 3 Self-adhesive mica tape product performance

[0085]

[0086] According to Table 1, Figure 2 and Figure 3 From the performance of the modified calcined mica paper, it can be seen that the titanate coupling agent JN114 can effectively activate the mica surface, allowing the silane coupling agent KH550 and bisphenol A cyclic carbonate to combine more with the mica to improve the toughness of the mica paper. At the same time, the alternating sizing method of fine pulp and coarse pulp can obtain mica paper with better tensile strength and tear strength.

[0087] According to the results in Tables 2 and 3, there is not much difference in thermal conductivity, volume resistivity, and breakdown field strength between the non-self-adhesive mica and the self-adhesive mica paper obtained in the examples. A comparison of the results of Comparative Examples 6 and 7 with those of the examples shows that after aluminum nitride and aluminum oxide are ball-milled and mixed with the modified calcined mica, the thermal conductivity of the mica tape is significantly improved due to the synergistic effect between aluminum nitride and aluminum oxide, allowing the mica tape to dissipate heat in a timely manner and prevent aging due to excessive temperatures. At the same time, a comparison of the results of Comparative Examples 2 and 3 with those of the examples shows that the silane coupling agent KH550 and bisphenol A cyclocarbonate have a synergistic effect, which can effectively improve the insulation performance of the mica tape.

[0088] Accelerated aging simulation test: The self-adhesive mica tape samples prepared in Example 1, Example 2, Example 4, Comparative Example 2, Comparative Example 3, Comparative Example 6 and Comparative Example 7 were irradiated with 3 x 2.0kW xenon lamps for continuous illumination at an average radiation intensity of 550W / m 2The temperature is (180±5)℃; the distance between the light source and the sample is 100-300mm; the aging time is 30d, and the thermal conductivity, volume resistivity and breakdown field strength of these samples are tested every 10d. The test results are as follows Figure 4 、 5 and as shown in Table 4.

[0089] according to Figure 4 、 Figure 5 As shown in Table 4, after 30 days of aging test, the sample prepared in Example 3 has excellent anti-aging performance. According to the comparison of the results of Comparative Examples 2 and 3 with those of Examples 1 and 2, the volume resistivity and breakdown field strength of the products obtained in Examples 1 and 2 did not change much after 30 days of aging due to the synergistic effect between the silane coupling agent KH550 and bisphenol A cyclic carbonate. However, for Comparative Examples 2 and 3, not only the initial thermal conductivity, volume resistivity and breakdown field strength were significantly reduced, but also the volume resistivity and breakdown field strength values ​​were also reduced after 30 days of aging. Figure 4 、 5 Comparing the results of Comparative Examples 6 and 7 in Table 4 with the results of Example 4, it can be seen that after 30 days of aging test, the thermal conductivity of Comparative Examples 6 and 7 is significantly reduced, while the thermal conductivity of Example 4 does not change much, indicating that the addition of aluminum nitride and aluminum oxide also has certain synergistic anti-aging properties, which can enable the thermal conductivity of the sample prepared in Example 4 to maintain a high level after 30 days of aging.

[0090] Table 4

[0091]

[0092] High temperature resistance test: The modified calcined mica paper prepared in Example 4, Comparative Example 6 and Comparative Example 7 was heated to 500°C in a muffle furnace for 50 hours for high temperature resistance test. After the test, the thermal conductivity, volume resistivity and breakdown field strength of the modified calcined mica paper prepared in Example 4, Comparative Example 6 and Comparative Example 7 were tested. The results are shown in Table 5.

[0093] Table 5

[0094]

[0095] According to Table 5, after the modified calcined mica paper prepared in Example 4 was calcined at 500°C for 60 hours, its thermal conductivity, volume resistivity and breakdown field strength were almost unchanged compared with the original mica paper, while the thermal conductivity, volume resistivity and breakdown field strength of Comparative Examples 6 and 7 were significantly reduced, further demonstrating the synergistic effect between aluminum nitride and aluminum oxide, which can effectively improve the high temperature resistance of mica paper.

[0096] The above-described embodiments merely represent specific implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of protection of the present invention. It should be noted that, for those skilled in the art, any changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention are equivalent replacements and are included within the scope of protection of the present invention.

Claims

1. A method for preparing a modified mica insulating material, characterized in that: The specific synthesis steps are as follows: S1. Take 30-50 g of calcined muscovite with a particle size of 200-800 mesh and stir it with 1-1.5 L of deionized water at a rate of 60-120 rpm for 2-4 hours to obtain a calcined muscovite slurry. Then, heat it to 60-110 ° C, add 0.5-1 g of titanate coupling agent JN114, and continue stirring for 1-3 hours. After activation is completed, place it in an electric constant temperature blower, set the temperature to 60-110 ° C, and dry it for 6-12 hours to obtain activated calcined mica; S2, take 20-30 g of the activated calcined mica in step S1 and 100-200 ml of ethanol-water solution in a volume ratio of 1:1, stir continuously at room temperature for 1-3 h, after mixing evenly, use 1.5 mol / L acetic acid solution to adjust the pH of the reaction solution to 3-4, then add 10 g of silane coupling agent KH550, continue stirring for 12-24 h, raise the reaction temperature to 60-80 ° C and continue stirring for 3-5 h, after the reaction is complete, cool the product to room temperature and filter, wash the filter cake with ethanol-water solution 3-5 times, and dry it at 60 ° C for 12-24 h to obtain a silane-modified calcined mica material; S3, take 20-30 g of bisphenol A epoxy resin and dissolve it in a mixed solution of 15-30 ml of 2-ethoxyethanol and 5-10 ml of methyl vinyl pyrrolidone, add 0.2-0.5 g of tetraethylammonium bromide and 0.05-0.1 g of anhydrous ZnCl2 while stirring, after the added substances are completely dissolved, transfer it to a high-pressure reactor, then pass carbon dioxide into it for 2-3 times, after the gas in the reactor is purged, pressurize it with carbon dioxide to 0.4-0.6 MPa, set the reaction temperature to 100-130°C, stir the reaction for 12-24 h, after the reaction is completed, use water-ethyl acetate with a volume ratio of 1:3 to extract the mixed solution for 3-5 times, and the yellow solution finally obtained is bisphenol A cyclic carbonate; S4. Mix the bisphenol A cyclic carbonate obtained in step S3 with 5-10 ml of acetone, stir at 30-40 ° C for 30-60 min, and after complete dissolution, add 2-3 ml of isophorone diamine and 0.5-2 ml of 1,8-diazabicyclo[5.4.0]undec-7-ene, reflux and mix at 60-80 ° C for 1-3 h, then add 10-15 g of the silane-modified calcined mica material obtained in step S2, continue stirring for 1-2 h, and after the reaction is complete, dry it at 110 ° C for 12 h and at 60 ° C for 12 h, then mix the dried material with aluminum nitride and aluminum oxide in a mass ratio of 1:0.1-0.3:0.1-0.3 and ball mill for 1-2 h. After the ball milling is completed, collect the material to obtain a hydroxyl polyurethane hybrid calcined mica material, that is, a modified mica insulating material.

2. The method for preparing a modified mica insulating material according to claim 1, wherein: The particle size of the calcined muscovite in step S1 is 400 mesh.

3. The method for preparing a modified mica insulating material according to claim 2, wherein: The amount of titanate coupling agent JN114 added in step S1 is 0.7 g.

4. The method for preparing a modified mica insulating material according to claim 2, wherein: The amount of activated mica added in step S2 is 20 g.

5. The method for preparing a modified mica insulating material according to claim 3, wherein: The carbon dioxide pressure in step S3 is 0.6 MPa.

6. The method for preparing a modified mica insulating material according to claim 4, wherein: The amount of isophorone diamine added in step S4 is 2.8 ml.

7. A heat-resistant mica tape, characterized by: The modified mica insulating material is prepared by the preparation method of the modified mica insulating material according to any one of claims 1 to 6.

8. A process for producing the heat-resistant mica tape according to claim 7, characterized in that: The following steps are involved: S5. Preparation of modified calcined muscovite paper: Pulping: The modified mica insulating material prepared by the method for preparing a modified mica insulating material according to any one of claims 1 to 6 is placed in a pulping machine and crushed and pulped using high-pressure water at a pressure of 6 MPa. The prepared modified mica pulp is graded and dehydrated using three dewatering screens of 14 mesh, 80 mesh, and 200 mesh. The obtained 14-80 mesh coarse pulp and 80-200 mesh fine pulp are placed in a pulp storage tank and stored separately for later use. Papermaking: regulating the sizing order of modified mica coarse pulp and modified mica fine pulp, sequentially performing the first sizing of modified mica fine pulp, the sizing of modified mica coarse pulp, and then the second sizing of mica fine pulp, and finally performing rotary screen papermaking, drying the prepared modified mica paper to a moisture content of 0.2%-0.5% to obtain modified calcined muscovite mica paper, wherein the sizing amount of modified mica fine pulp is the same for the two times, and the mass ratio of mica coarse pulp to mica fine pulp during sizing is controlled to be 1-2:1; S6. Preparation of non-self-adhesive mica tape: coating a polyester film with an adhesive and laminating the tape with modified calcined mica paper under heating and pressure at 100-150° C., followed by drying, winding, and slitting to obtain a non-self-adhesive mica tape product; S7. Preparation of self-adhesive mica tape: corona-treat the back of the polyester film, apply self-adhesive glue and dry it, apply adhesive and heat-press the modified calcined mica paper at 100-150°C and laminate them, then dry, roll and slit to obtain the self-adhesive mica tape product.

9. The production process of a heat-resistant mica tape according to claim 8, characterized in that: In step S5, the mold is first heated to 80-110°C, the pressure is 0.6 MPa and the duration is 45 seconds, second heated to 120-150°C, the pressure is 0.8 MPa and the duration is 140 seconds, and third cooled to room temperature at a cooling rate of 10°C / min.

10. The production process of a heat-resistant mica tape according to claim 8, characterized in that: In step S6, the polyester film is coated with an adhesive and then laminated with the modified calcined mica paper under heating and pressure at 120°C.

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