阅读说明：本技术 一种高导热云母纸的改性制备方法 (Modified preparation method of high-thermal-conductivity mica paper ) 是由 吴海峰 赵建虎 苏潜 赵俊军 于 2020-05-13 设计创作，主要内容包括：本发明公开了一种高导热云母纸的改性制备方法,该改性制备方法将云母原料处理成粗浆料以及细浆料,然后以纳米BN以及纳米级硅化合物粉末的混合物作为填料,一并加入阳离子淀粉、乙二胺四乙酸、五溴苯酚的混合物水溶液制成填料溶液,并将填料溶液与经过硅烷偶联剂改性后的对位芳纶短切纤维进行混合后进行超声分散,并抄造成型于云母纸的粗浆料层与细浆料层之间,再通过脱水、烘干,即可得到高导热云母纸。本发明的高导热云母纸应用于大、中型高压发电机、电动机等电力设备时具备优异的机械强度、介电击穿强度以及高导热稳定性。(The invention discloses a modification preparation method of mica paper with high thermal conductivity, which comprises the steps of processing mica raw materials into coarse slurry and fine slurry, then taking a mixture of nano BN and nano silicon compound powder as a filler, adding a mixture aqueous solution of cationic starch, ethylene diamine tetraacetic acid and pentabromophenol together to prepare a filler solution, mixing the filler solution and para-aramid chopped fibers modified by a silane coupling agent, carrying out ultrasonic dispersion, carrying out papermaking forming between a coarse slurry layer and a fine slurry layer of the mica paper, and carrying out dehydration and drying to obtain the mica paper with high thermal conductivity. The mica paper with high thermal conductivity has excellent mechanical strength, dielectric breakdown strength and high thermal conductivity stability when being applied to electric equipment such as large and medium-sized high-voltage generators, motors and the like.)

1. A modification preparation method of high-thermal-conductivity mica paper is characterized by comprising the following operation steps:

s1, mica pulping: cleaning and removing impurities from a mica raw material, crushing the mica raw material into mica flakes by using a high-pressure hydraulic crusher, washing, filtering and screening the crushed mica flakes into-20 to +80 meshes and-80 to +200 meshes, and respectively preparing the two mica flakes into coarse slurry and fine slurry with different concentrations for surfing the net by using water;

s2, preparing a filler solution: diluting the filler with water by a stirrer, adding a mixture aqueous solution of cationic starch, ethylenediamine tetraacetic acid and pentabromophenol together, continuously stirring, and keeping the mixture uniformly distributed; wherein the filler comprises a mixture of nanometer BN and nanometer silicon compound powder, and the nanometer oxide powder is SiC or Si₃N₄、SiO₂In a mixture of proportions of (A) and (B), SiO in the nanoscale oxide powder₂The proportion of the components is not less than 17 percent;

s3, preparing a modified fiber dispersion liquid: modifying the para-aramid chopped fibers by using a silane coupling agent KH550, adding the filler solution prepared in the step S2, and performing ultrasonic-assisted shearing dispersion to obtain a modified fiber dispersion solution;

s4, paper pulp making: papermaking by using a cylinder mould mica paper machine, sizing on the cylinder mould by three times, sizing by using coarse sizing agent for the first time and the third time, sizing by using fine sizing agent for the second time, and spraying the modified fiber dispersion liquid prepared in the step S3 on the surface of the sizing agent once after each sizing;

s5, dewatering and drying: after spraying, the mica paper with high thermal conductivity can be obtained by dehydration and drying.

2. The method for preparing the modified mica paper with high thermal conductivity according to claim 1, wherein the coarse slurry and the fine slurry are both added with water-soluble high temperature resistant adhesives, the water-soluble high temperature resistant adhesives added in the coarse slurry account for 2-5% of the weight of the corresponding mica flakes, and the water-soluble high temperature resistant adhesives added in the fine slurry account for 0.8-3% of the weight of the corresponding mica flakes.

3. The modified preparation method of mica paper with high thermal conductivity according to claim 1, wherein the chopped para-aramid fiber adopted in step S2 has a fiber filament length of 7-12 mm and a fineness of 1.5D.

4. The modified preparation method of mica paper with high thermal conductivity according to claim 1, wherein the mass concentration of the silane coupling agent KH550 in the step S2 is 3-10%.

5. The method for modifying mica paper with high thermal conductivity according to claim 1, wherein in the filler solution prepared in step S2, the mass ratio of cationic starch, ethylenediamine tetraacetic acid, and pentabromophenol is 1.4-1.7%, 2.3-3.5%, and 3.2-3.5%, respectively, and the mass ratio of the filler composed of nano BN and nano silicon compound powder in the filler solution is 3-7%, and the volume ratio of nano BN to nano silicon compound powder is 1: 3-1: 5.

6. The method for preparing the mica paper with high thermal conductivity according to claim 1, wherein in the modified fiber dispersion liquid prepared in the step S3, the addition proportion of the para-aramid chopped fibers in the filler solution is a material-to-liquid ratio of 1: 20-1: 30.

7. The method for preparing the mica paper with high thermal conductivity according to claim 1, wherein the ultrasonic dispersion conditions are controlled in the step S3 when ultrasonic-assisted dispersion is carried out: shearing rotating speed: 2500-3000 rad/min, ultrasonic frequency: 30 KHz-50 KHz, ultrasonic power: 40-60W, and the shearing operation time is 20-45 min.

8. The method for preparing the mica paper with high thermal conductivity according to claim 1, wherein the single-layer thickness of the coarse-pulp mica paper layer of the formed mica paper with high thermal conductivity is 1/3 of the thickness of the fine-pulp mica paper layer, and the mass ratio of the formed para-aramid chopped fibers in the mica paper with high thermal conductivity is 5-9%.

9. The application of the mica paper with high thermal conductivity prepared by the preparation method of any one of claims 1 to 8 in high-voltage generators, high-power motors and medium-large transformers.

Technical Field

The invention relates to the field of insulating mica products, in particular to a method for preparing high-thermal-conductivity mica paper by modification.

Background

With the continuous improvement of the living standard of people and the development of electric power systems, the electric power industry has become a considerable important development object in various countries, the demand of production and living behaviors on electric power equipment is also continuously increased, the capacity and the voltage withstanding degree of large and medium-sized high-voltage motors are also continuously expanded, and the insulation protection requirements of corresponding electric power equipment are higher and higher. Compared with the traditional metal insulating material, the mica paper has excellent electrical properties such as high electrical strength, low dielectric loss, high surface resistance, high volume resistance and the like, and physical and chemical properties such as heat resistance, water resistance, chemical stability, high elasticity, high peeling property, great shearing force resistance, tensile strength and the like, and can effectively break through the use range and use limit of the metal insulating material.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for modifying and preparing mica paper with high thermal conductivity, so as to solve the defects in the background technology.

The technical problem solved by the invention is realized by adopting the following technical scheme:

a modification preparation method of high-thermal-conductivity mica paper specifically comprises the following operation steps:

s1, mica pulping: cleaning and removing impurities from a mica raw material, crushing the mica raw material into mica flakes by using a high-pressure hydraulic crusher, washing, filtering and screening the crushed mica flakes into-20 to +80 meshes and-80 to +200 meshes, and respectively preparing the two mica flakes into coarse slurry and fine slurry with different concentrations for surfing the net by using water;

s2, preparing a filler solution: diluting the filler with water by a stirrer, adding a mixture aqueous solution of cationic starch, ethylenediamine tetraacetic acid and pentabromophenol together, continuously stirring, and keeping the mixture uniformly distributed; wherein the filler comprises a mixture of nanometer BN and nanometer silicon compound powder, and the nanometer oxide powder is SiC or Si₃N₄、SiO₂In a mixture of proportions of (A) and (B), SiO in the nanoscale oxide powder₂The proportion of the components is not less than 17 percent;

s3, preparing a modified fiber dispersion liquid: modifying the para-aramid chopped fibers by using a silane coupling agent KH550, adding the filler solution prepared in the step S2, and performing ultrasonic-assisted shearing dispersion to obtain a modified fiber dispersion solution;

s4, paper pulp making: papermaking by using a cylinder mould mica paper machine, sizing on the cylinder mould by three times, sizing by using coarse sizing agent for the first time and the third time, sizing by using fine sizing agent for the second time, and spraying the modified fiber dispersion liquid prepared in the step S3 on the surface of the sizing agent once after each sizing;

s5, dewatering and drying: after spraying, the mica paper with high thermal conductivity can be obtained by dehydration and drying.

And as a further limitation, water-soluble high-temperature-resistant adhesives are added into the coarse slurry and the fine slurry, wherein the water-soluble high-temperature-resistant adhesives added into the coarse slurry account for 2-5% of the weight of the corresponding mica flakes, and the water-soluble high-temperature-resistant adhesives added into the fine slurry account for 0.8-3% of the weight of the corresponding mica flakes.

Further, the chopped para-aramid fibers used in step S2 have a fiber filament length of 7 to 12mm and a fineness of 1.5D.

Further, in the step S2, the concentration of the silane coupling agent KH550 is 3-10% by mass.

By way of further limitation, in the filler solution prepared in step S2, the preferred mass ratios of cationic starch, ethylenediaminetetraacetic acid and pentabromophenol are 1.4 to 1.7%, 2.3 to 3.5% and 3.2 to 3.5%, respectively, while the mass ratio of the filler composed of the nano BN and the nano-sized silicon compound powder in the filler solution is 3 to 7%, and the volume ratio of the nano BN to the nano-sized silicon compound powder is 1:3 to 1: 5.

By way of further limitation, in the modified fiber dispersion liquid prepared in the step S3, the addition proportion of the para-aramid chopped fibers in the filler solution is in a material-to-liquid ratio of 1: 20-1: 30.

By way of further limitation, the ultrasonic dispersion conditions are controlled when performing ultrasonic-assisted dispersion in step S3 as follows: shearing rotating speed: 2500-3000 rad/min, ultrasonic frequency: 30 KHz-50 KHz, ultrasonic power: 40-60W, and the shearing operation time is 20-45 min.

The single-layer thickness of the coarse pulp mica paper layer of the formed high-thermal-conductivity mica paper is 1/3-1/4 of the thickness of the fine pulp mica paper layer, and the mass ratio of the para-aramid chopped fibers in the high-thermal-conductivity mica paper after forming is 5-9%.

Has the advantages that: the high-thermal-conductivity mica paper prepared by the method has moderate strength and good paper forming stability, can keep the electrical property of the mica paper, and can increase the thermal conductivity coefficient of the mica paper from 0.35-0.50W/mK of the traditional mica paper with the same material to 0.8W/mK or above, and can resist the long-term use temperature of more than 300 ℃; meanwhile, the stability and tensile property of the whole structure of the insulating layer can be effectively guaranteed, the secondary processing property is more excellent, a high-quality novel insulating material is provided for the electromechanical field, the method is an important way for preparing high-quality novel composite mica insulating paper, and the method has great market prospect and practical significance

Drawings

FIG. 1 is a schematic longitudinal sectional view of the preferred embodiment of the present invention.

Wherein: 1. a second coarse pulp mica paper layer; 2. a second modified fiber filler layer; 3. a fine slurry mica paper layer; 4. a first modified fiber filler layer; 5. a first coarse pulp mica paper layer.

Detailed Description

In order to make the technical means, the creation features, the achievement purposes and the effects of the invention easy to understand, the invention is further described below by combining the specific drawings and the embodiments.

In the following examples, it will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

In this embodiment, the preparation method of the mica paper with high thermal conductivity by modification is carried out in the following manner:

firstly, selecting mica sheet raw materials for removing dead materials and broken materials, screening the mica sheet raw materials, and selecting a single sheet with the area less than or equal to 10cm²And taking mica sheets with the thickness of less than or equal to 3cm as a raw material, washing the mica raw material, secondarily removing impurities and washing, putting the washed mica chips into clear water with the mass 4-5 times that of the mica chips, adding the clear water into a high-pressure hydraulic crusher, controlling the water pressure to be 5.5-6 MPa, and crushing the mica chips into mica flakes by utilizing water power. Washing, filtering and screening the crushed mica flakes into two parts of-20 to +80 meshes and-80 to +200 meshes, and filtering by a dewatering screenThe mica scales are respectively mixed with water to prepare raw slurry, the concentration of the mica scales in the raw slurry is 30 +/-5 percent, and the raw slurry is respectively conveyed to two thick slurry tanks for standby by pipelines.

Mixing nanometer BN and nanometer silicon compound powder as filler, wherein the nanometer silicon compound powder is SiC or Si₃N₄、SiO₂The mass ratio of the nano BN to the nano silicon compound powder is 1:1:1, the nano BN and the nano silicon compound powder are divided into ten groups, and the ratio of the nano BN in the ten groups is gradually reduced and is changed in equal proportion; diluting the filler with water, adding a mixture aqueous solution of cationic starch, ethylenediamine tetraacetic acid and pentabromophenol together, controlling the mass ratio of the cationic starch, the ethylenediamine tetraacetic acid and the pentabromophenol in the mixture aqueous solution to be 1.5%, 3% and 3.3% respectively, controlling the mass ratio of the filler in the mixture aqueous solution to be 5%, and continuously stirring to keep the mixture uniformly distributed to obtain a solution A; meanwhile, selecting para-aramid chopped fibers with fiber monofilament lengths of 7-12 mm and fineness of 1.5D, modifying with a silane coupling agent KH550 with mass concentration of 8%, adding the modified para-aramid chopped fibers into the solution A, controlling the addition amount of the modified para-aramid chopped fibers to enable the mass ratio relation of the para-aramid chopped fibers to be 1:25 in the filler solution, performing ultrasonic-assisted shear dispersion, and controlling the shear rate of ultrasonic shear to be 2800rad/min, the ultrasonic power to be 45W, the frequency to be 45KHz, and dispersing for 30min to obtain a modified fiber dispersion liquid.

Then taking the slurry in a thick slurry tank, using water and a water-soluble epoxy adhesive or a water-soluble organic silicon adhesive as water-soluble high-temperature-resistant adhesives to prepare coarse slurry and fine slurry with different concentrations for surfing the net, and controlling the thickness of the formed mica paper layer according to different sizing concentrations; the water-soluble high-temperature-resistant adhesive added into the coarse slurry accounts for 3% of the weight of the corresponding mica flake, and the water-soluble high-temperature-resistant adhesive added into the fine slurry accounts for 2% of the weight of the corresponding mica flake, so that the forming is convenient.

And then making paper by using a cylinder mould mica paper machine, sizing the paper by using cylinder moulds for three times, sizing the paper by using coarse sizing agents for the first time and the third time, sizing the paper by using fine sizing agents for the second time, spraying the modified fiber dispersion liquid prepared in the step S3 on the surface of the sizing agent once after each sizing, and controlling the spraying amount and the uniformity of the modified fiber dispersion liquid so that the mass ratio of the formed para-aramid chopped fiber in the high-thermal-conductivity mica paper is 6-8%, and dehydrating and drying the paper after spraying until the comprehensive water content is 0.2-0.5%, thereby obtaining the high-thermal-conductivity mica paper. If necessary, hot-press molding can be carried out, the hot-press temperature is controlled to be 280-380 ℃, the linear pressure is 250-300 kN/m, the roller speed is 1.0-4.0 m/min, and the hot-press frequency is 1-3 times.

The structure of the formed mica paper is shown in fig. 1, and the formed mica paper comprises a first coarse pulp mica paper layer 5 which is formed firstly, a first modified fiber filler layer 4 which is sprayed on the surface of the first coarse pulp mica paper layer 5 and is formed, a fine pulp mica paper layer 3 which is formed after secondary circular screen sizing, a second modified fiber filler layer 2 which is sprayed on the surface of the fine pulp mica paper layer 3 and is formed, and a second coarse pulp mica paper layer 1 which is formed after sizing finally.

Wherein, the thickness of the first coarse sizing agent mica paper layer 5 is consistent with that of the second coarse sizing agent mica paper layer 1, and is 1/4 of the thickness of the fine sizing agent mica paper layer; and the mass ratio of the para-aramid chopped fibers in the first modified fiber filler layer 4 and the second modified fiber filler layer 2 in the mica paper with high thermal conductivity is 6-7%.

In this example, the mica paper of the same thickness commercially available as a comparative group was cut to obtain a 20mm 200mm paper tape, and the measured thermal conductivity of the mica paper of the same thickness commercially available as a comparative group was 0.46W/mK, 0.84W/mK, 0.95W/mK, 1.02W/mK, 1.08W/mK, 1.12W/mK, 1.14W/mK, 1.15W/mK, and the electrical properties of the mica paper of the same thickness commercially available as a comparative group or a slightly lower paper base were measured under the conditions of 27 ℃ and 50% relative humidity and ten sets of different nano BN ratios, meanwhile, the paper has good evenness, excellent mechanical strength, dielectric breakdown strength and high temperature resistance stability.

From the above results, it can be found that the use of the high thermal conductivity of BN and the silicon compound is more beneficial to improve the comprehensive thermal conductivity of the cured mica tape, and as the proportion of BN in the filler increases, the thermal conductivity of the high thermal conductivity mica paper continuously increases, but the increase rate is generally increased and then decreased.

The BN and the inorganic silicon compound are poor in binding performance with mica, mostly are bound through intermolecular van der Waals force, are poor in stability, and easily form a fault after long-term use; the chopped aramid fiber is modified by the silane coupling agent KH550, so that the bonding performance of mica paper and the chopped aramid fiber is improved, the bonding performance of a fiber space structure in the modified chopped aramid fiber and nano-scale particles is improved, the mechanical difference between a coarse pulp sheet raw material mica paper layer and a fine pulp sheet mica paper layer which are used in a layering mode and have different particle sizes is combined, the difference of rapid and obvious change of acting force between layers is reduced to fix BN and an inorganic silicon compound, the stability of the internal structure can be improved on the basis of reasonably adjusting the proportion of the using amounts of the BN and the inorganic silicon compound, and the preparation difficulty is reduced. Compared with the traditional aramid fiber reinforced mica paper, the composite heat-conducting mica paper has more excellent heat-conducting property with composite reinforcing effect, has stable thermal property, obviously improves the performance compared with the traditional commercially available mica paper, and is particularly suitable for being applied to high-voltage generators, high-power motors and medium-large transformers.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.