Mica is a naturally occurring layered silicate mineral. It has excellent physical and electrical properties and maintains the above properties at high temperature. It has complete chemical inertia and non-flammability. Most importantly, it has the characteristics of high voltage, corona discharge resistance and radiation protection. Therefore, as a very important insulating material, it is widely used in electronics, motors, telecommunications, electrical appliances, aviation, transportation, instrumentation, metallurgy, building materials, light industry and other industrial sectors, as well as in national defense and cutting-edge industries.

But the utilization rate of mica is too low when mica products are processed from mica raw ore. In order to make full use of the crushed mica resources, mica paper emerges as the times require. Since the appearance of mica paper, mica paper has made great contributions to the comprehensive utilization of mica and as the base material of electrical insulation materials. So mica paper manufacturing technology goes hand in hand with large-scale integrated circuits, high-temperature plastics and optical fibers. It is known as the four major technologies contributing to the contemporary electrical and electronic industry.

1. Classification of Mica Paper

Mica paper is a kind of paper-like non-metallic mineral material. It is made of fine fragmented mica. First, mica is crushed into fine scales by crushing. Without any binder, it is graded and pulped. Then, on the mica paper machine, it is manufactured and pressed and dried by van der Waals attraction. Mica paper of wood.

Mica paper is made entirely of pure natural mica scales without any cellulose or other organic substances, so the only similarity between mica paper and ordinary paper is its final product and production method. Mica paper keeps the excellent properties of natural mica, and has uniform thickness, small fluctuation range of dielectric strength, high and stable corona starting voltage; its dielectric loss voltage characteristics are much more stable than mica insulation, good thermal conductivity and low temperature rise in use. Moreover, mica paper has all kinds of products corresponding to mica sheets, so it has replaced natural mica sheets in many fields.

Mica paper in China can be roughly divided into: Calcined mica paper called powder mica paper, commonly known as cooked paper, model 501, 501-1, 502 (with a small amount of glue), 503, 511 (capacitor mica paper). Water-flushing mica paper, commonly known as raw paper, can also be divided into recycled mica paper (model 506, 507, 508, 813, 814), synthetic mica paper, mica paper. Large scale mica paper, models 506, 507, 508, 813, 814. Mixed pulp mica paper, models 510, 501-2. These mica papers with different characteristics have been widely used in the domestic electrical industry. At present, mica papers are almost used as main insulation in large motors.

2. Production Process and Flow of Mica Paper

The production process of mica paper mainly includes seven steps: crushing, grading, pulping, manufacturing, forming, pressing and drying. The four steps of making, forming, pressing and drying are quite mature in the production of mica paper, so the three processes of mica pulverization, grading and pulping are the most important parts in the whole production process of mica paper. The three processes directly affect the quality and performance of mica paper. Crushing is the basis of mica paper production. Only by adopting appropriate crushing methods can mica scales with smooth surface, uniform particle size and large diameter-thickness ratio be obtained without destroying the physical properties of natural mica. Grading is the key to mica paper production. Grading can remove the particles that do not meet the requirements of paper making and retain the suitable size. Mica pulping is the core of mica paper production. Through grading process, mica powder which meets the requirements of paper making can be obtained. Only through grading pulping in a certain proportion, can the best formulation for high performance mica paper production be obtained and mica paper with high performance be manufactured.

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