Ⅰ. What are mica products?
Mica products are products composed of sheet mica or powder mica paper and various adhesives and reinforcing materials. They are used as the main insulation of high-voltage motor coils and insulation materials for motors and electrical appliances. Mica has high electrical properties, corona resistance, heat resistance, and mechanical properties, so mica products have become the main insulating material in the manufacture of televisions and electrical appliances.
In the early days of the founding of the People’s Republic of China, it was only possible to produce sheet mica products with natural resins—shellac, asphalt and synthetic resin alkyd resins as binders and paper and silk as reinforcing materials.
With the development of the electrical industry, the motor capacity and voltage level continue to increase, and the requirements for mica products are also getting higher and higher. It can produce asphalt, shellac, alkyd, epoxy resin, silicone resin, polyester, polyesterimide, polyimide, etc. as adhesives, and paper, silk, alkali-free glass cloth, film, etc. as reinforcement.
Ⅱ. Types of mica products
Mica products are classified according to their different characteristics according to composition, shape, process characteristics and scope of use. According to their components, they can be divided into sheet mica and powder mica products, and mica products with and without reinforcing materials.
According to its structural shape and process characteristics, it is divided into mica tape, mica board (soft mica board, plastic mica board, commutator mica board, liner mica board, heat-resistant mica board) and mica foil.
According to different molding methods, mika tape can be divided into molded multi-adhesive mica tape and overall impregnated less-adhesive mica tape. Mica is a heat-resistant insulating material, so the heat-resistant grade of the product mainly depends on the adhesive and reinforcing material.
Mica products are a class of insulating materials. Because of its good electrical insulation and high heat resistance, so far, most of the important insulation parts of high-voltage motors are insulated with mica.
Ⅲ. The general requirements for various types of mica products are as follows:
1. The mica tape should have softness and certain tensile strength at room temperature so that it will not break when it is wound. The mica tape used for high-voltage motor coils should have sufficient withstand voltage strength and small dielectric loss, and the thickness of the mica tape should be uniform.
2. The plastic mica sheet has the possibility of being made into complex shapes in the hot state, and the non-deformable soft mica board has good flexibility at room temperature.
3. Liner mica board has a small delamination rate and is suitable for punching or shearing processing to manufacture various gaskets or spacers. The commutator mica plate requires uniform thickness, good tightness, low shrinkage under high temperature and high pressure, no mica slippage and no adhesive flow out, etc.
4. Mica foil should have the same plasticity as molded mica board.
5. Heat-resistant mica board, in addition to good electrical insulation performance and low mechanical strength, its outstanding characteristics are good moisture resistance, less smoke when heated, and can work for a long time at 600 ° C or 700 ~ 1000 ° C for a long time.