CN114214864A - A method for preparing high thermal conductivity mica paper based on ice template method - Google Patents

Abstract

The invention discloses a preparation method of high-thermal-conductivity mica paper, which comprises the following steps: 1) uniformly stirring the heat-conducting filler, the adhesive and the dispersing agent, further mixing the mixture with mica powder and water, and placing the prepared slurry with proper concentration into a head box; 2) spraying the slurry on the net, and quickly freezing the upper net paper material on a forming plate in a one-way manner; 3) and (3) freeze-drying, squeezing and compacting the frozen paper material, and finally performing calendaring modification to obtain the high-thermal-conductivity mica paper. The mica paper prepared by the method has higher longitudinal thermal conductivity and better air permeability and insulating property under the condition of lower filler content.

Description

Method for preparing high-thermal-conductivity mica paper based on ice template method

Technical Field

The invention relates to the technical field of production and manufacture of main insulation high-thermal conductivity mica paper of medium and large motors, and particularly relates to a method for manufacturing high-thermal conductivity mica paper.

Technical Field

The mica paper is a paper-like non-metal insulating material which is prepared by combining broken mica as a raw material under the combined action of Van der Waals force and electrostatic attraction between mica scales, and maintains the performances of high temperature resistance, high voltage resistance, insulation resistance, corona resistance and the like of natural mica. Mica paper is widely applied to the production of high-voltage motors in the electrical industry. In order to adapt to the continuous development of industrial electricity and the continuous improvement of the requirement on the insulating property of the motor, the development of the mica insulating material with high heat conductivity has very important significance. However, the existing mica paper has the problems of poor air permeability, poor electrical insulation performance and the like after being added with the heat-conducting filler, so that the mica paper has poor heat dissipation performance in the operation process after being applied to a high-voltage motor, and the insulation electrical performance, mechanical performance and service life are reduced. Therefore, how to improve the pressure resistance and the thermal conductivity of the mica paper insulating material is an urgent problem to be considered and solved.

Disclosure of Invention

The invention provides a preparation method of a high-thermal-conductivity mica paper material for a high-voltage motor, aiming at solving the defect that the existing motor main insulation mica paper has low insulation level and poor thermal conductivity. The filler forms a rapid heat conduction channel in the mica paper in the direction perpendicular to the paper surface by the ice template technology, and meanwhile, the mica paper has good air permeability due to a porous structure generated by moisture volatilization in the drying process. The finally prepared mica paper material with high heat conductivity has good heat dissipation performance and heat conductivity.

The invention is realized by the following technical scheme: a method for preparing oriented high-thermal-conductivity mica paper by a freeze casting technology comprises the following steps:

(1) weighing a certain mass proportion of the heat-conducting filler, the binder and the dispersant, mixing and stirring uniformly.

(2) And (2) adding a proper amount of mica powder and the solution obtained in the step (1) into a certain mass of water, and stirring until the slurry is uniform.

(3) And (3) feeding the slurry obtained in the step (2) into a slurry tank, and spraying the slurry onto the wire near the center line of the breast roll at a spraying speed close to the wire speed. After the paper material is conveyed to the upper part of the forming plate filled with liquid nitrogen, the water in the slurry is quickly crystallized in the direction vertical to the forming plate, the mica powder, the filler and the binder are intensively extruded among the ice crystals, and the mica paper pulp realizes the directional freezing.

(4) And (4) conveying the frozen paper stock formed in the step (3) to a freeze drying device through a paper guide roller for freeze drying to enable the water content of the mica paper to be lower than 5%, and further conveying the mica paper to a pressing part for multiple pressing treatments to reduce the thickness of the mica paper and increase the density and contact area of the filler. And then drying, cooling in a cold cylinder and coiling to obtain the required mica paper with high thermal conductivity.

The binder is one or more of polyvidone, polyethylene glycol, methylcellulose, carboxymethylcellulose sodium or polyvinyl alcohol.

The heat conducting filler is one or more of boron nitride, silicon nitride, aluminum nitride, magnesium oxide, silicon oxide or aluminum oxide.

The dispersing agent is one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, acetic acid, acetone or toluene.

The mass ratio of the filler solution raw materials is as follows: heat-conducting filler: dispersant 1: 1-2: 1 to 10.

The mass ratio of the heat-conducting filler to the mica powder in the mica paper pulp is 1: 2-19, and adding water to adjust the solid content to 20% -30%.

The forming plate is a copper plate, and the purpose of quickly freezing the slurry above the copper plate is achieved by continuously injecting liquid nitrogen into the copper plate.

In the freeze drying device, the vacuum degree in a drying chamber is 10Pa, and the freezing temperature is-50 ℃.

Compared with the prior art, the invention has the beneficial effects that:

the mica paper prepared by the invention has the advantages that the heat conductivity is multiplied in the direction vertical to the paper surface due to the directional arrangement of the heat-conducting fillers, the paper has good air permeability due to more gaps formed by water volatilization in the drying process, and the impregnated mica paper has higher heat conductivity coefficient and breakdown field intensity.

Drawings

FIG. 1 preparation process of high thermal conductivity mica paper

Detailed Description

The technical solutions of the present invention are further described below with reference to the specific embodiments, but the present invention is not limited thereto, and any modifications or equivalent substitutions made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention should be covered by the protection scope of the present invention.

The embodiment provides a method for preparing high-thermal-conductivity mica paper by an ice template method, as shown in fig. 1, the specific implementation steps are as follows:

(1) 1kg of polyvinyl alcohol and 2kg of boron nitride powder were weighed into 7kg of acetone, and the mixed filler solution was stirred at 1000 revolutions using a disperser.

(2) Weighing 7kg of mica powder, adding the mica powder and the uniformly mixed filler solution into 1000kg of water, and fully stirring to prepare mica slurry with the concentration of 1%.

(3) Liquid nitrogen was continuously injected into the copper plate to maintain it in a low temperature state.

(4) The uniformly stirred slurry is fed into a slurry tank and sprayed onto the wire near the center line of the breast roll at a spraying speed close to the wire speed. After the paper material is conveyed to the upper part of the forming plate filled with liquid nitrogen, the water in the slurry is quickly crystallized in the direction vertical to the forming plate, the mica powder, the filler and the binder are intensively extruded among the ice crystals, and the mica paper pulp realizes the directional freezing.

(5) The frozen paper stock is conveyed to a freeze drying device through a paper guide roller for freeze-drying treatment, so that the water content of the mica paper is below 5 percent, and then the mica paper is conveyed to a pressing part for multiple pressing treatments to reduce the thickness of the mica paper and increase the density of the filler and the contact area. And then drying, cooling in a cold cylinder and coiling to obtain the required mica paper with high thermal conductivity.

In conclusion, compared with the existing products, the high-thermal-conductivity mica paper prepared by the invention has the advantages of simple preparation method, less filler consumption, good air permeability and lower cost, and the oriented high-speed thermal conduction channel is formed in the direction vertical to the surface of the mica paper, so that the thermal conductivity of the mica paper is improved exponentially.

Claims (8)

Translated fromChinese

1.一种高导热云母纸的制备方法，其特征在于，包括如下步骤：1. a preparation method of high thermal conductivity mica paper, is characterized in that, comprises the steps:(1)称取一定质量比例的导热填料、粘结剂和分散剂进行混合并搅拌均匀；(1) Weigh a certain mass proportion of thermally conductive filler, binder and dispersant, mix and stir evenly;(2)将适量云母粉和步骤(1)所得的填料溶液加入到一定质量的水中，搅拌到浆料均匀为止；(2) adding an appropriate amount of mica powder and the filler solution obtained in step (1) into water of a certain quality, and stirring until the slurry is uniform;(3)将步骤(2)所得的浆料投入流浆池中，以接近于网速的喷浆速度喷到胸辊中心线附近的网上，上网纸料被传送到装有液氮的成形板上方后，浆料中的水分在垂直于成形板方向迅速结晶，云母粉、填料和粘结剂被集中挤压到冰晶之间，云母纸浆实现定向冷冻；(3) put the slurry obtained in step (2) into the headstock, spray it on the wire near the center line of the breast roll at a spraying speed close to the wire speed, and the net paper material is transferred to a forming plate equipped with liquid nitrogen After the above, the moisture in the slurry crystallizes rapidly in the direction perpendicular to the forming plate, the mica powder, filler and binder are concentrated and squeezed between the ice crystals, and the mica pulp achieves directional freezing;(4)将步骤(3)成形的冰冻纸料通过引纸辊传送到冷冻干燥装置进行冻干，使云母纸张含水率5％以下，进而传送到压榨部进行多次压榨处理来减小云母纸厚度增大填料密度和接触面积，再通过干燥、冷缸冷却、卷取处理即可制得所需的高导热云母纸。(4) The frozen paper stock formed in step (3) is transferred to a freeze-drying device for freeze-drying through a threading roller, so that the moisture content of the mica paper is less than 5%, and then transferred to the pressing section for multiple pressing treatments to reduce the size of the mica paper The thickness increases the density of the filler and the contact area, and then the required high thermal conductivity mica paper can be obtained by drying, cooling in a cold cylinder, and coiling.2.根据权利要求1所述的一种高导热云母纸的制备方法，其特征在于步骤(1)所述的粘结剂为聚维酮、聚乙二醇、甲基纤维素、羧甲基纤维素、羧甲基纤维素钠或聚乙烯醇的一种或多种。2. the preparation method of a kind of high thermal conductivity mica paper according to claim 1 is characterized in that the described binder of step (1) is povidone, polyethylene glycol, methyl cellulose, carboxymethyl One or more of cellulose, sodium carboxymethylcellulose, or polyvinyl alcohol.3.根据权利要求1所述的一种高导热云母纸的制备方法，其特征在于步骤(1)所述的导热填料为氮化硼、氮化硅、氮化铝、氧化镁、氧化硅或氧化铝的一种或多种。3. The preparation method of a high thermal conductivity mica paper according to claim 1, wherein the thermally conductive filler described in step (1) is boron nitride, silicon nitride, aluminum nitride, magnesium oxide, silicon oxide or One or more of alumina.4.根据权利要求1所述的一种高导热云母纸的制备方法，其特征在于步骤(1)所述的分散剂为甲醇、乙醇、正丙醇、异丙醇、正丁醇、异丁醇、仲丁醇、叔丁醇、乙酸、丙酮或甲苯的一种或多种。4. the preparation method of a kind of high thermal conductivity mica paper according to claim 1, is characterized in that the described dispersant of step (1) is methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutyl One or more of alcohol, sec-butanol, tert-butanol, acetic acid, acetone or toluene.5.根据权利要求1所述的一种高导热云母纸的制备方法，其特征在于步骤(1)所述的原料的质量比为粘结剂：导热填料：分散剂＝1：1～2：1～10。5. the preparation method of a kind of high thermal conductivity mica paper according to claim 1 is characterized in that the mass ratio of the raw material described in step (1) is binder: thermal conductive filler: dispersant=1:1～2: 1 to 10.6.根据权利要求1所述的一种高导热云母纸的制备方法，其特征在于步骤(2)所述的导热填料与云母粉的质量比为＝1：2～19，并加水将固含量调节为20％～30％。6. the preparation method of a kind of high thermal conductivity mica paper according to claim 1 is characterized in that the mass ratio of the thermal conductive filler described in step (2) and mica powder is = 1: 2～19, and adding water will make the solid content Adjusted to 20% to 30%.7.根据权利要求1所述的一种高导热云母纸的制备方法，其特征在于步骤(3)所述的成形板为铜板，通过在铜板内部不断注入液氮从而达到将浆料在铜板上方快速冷冻的目的。7. the preparation method of a kind of high thermal conductivity mica paper according to claim 1, it is characterized in that the described forming plate of step (3) is copper plate, by continuously injecting liquid nitrogen inside the copper plate to achieve the slurry above the copper plate purpose of rapid freezing.8.根据权利要求1所述的一种高导热云母纸的制备方法，其特征在于步骤(4)所述的冷冻干燥装置中，干燥室内真空度为10Pa，冷冻温度为-50℃。8 . The method for preparing a high thermal conductivity mica paper according to claim 1 , wherein in the freeze-drying device described in step (4), the vacuum degree in the drying chamber is 10 Pa, and the freezing temperature is -50° C. 9 .

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