Insulating paper is usually a sheet-like material formed by plant fibers, mineral fibers, synthetic fibers or their mixtures, which are deposited on a paper machine through water or other media. Insulating paper has high tear strength, low elongation, and good insulation. Therefore, it is widely used as insulating material in motors, cables, capacitors and transformers. It is also used for insulating materials such as laminates, composites and prepregs. The main constituent materials. In recent years, with the development of the power industry, modern power generation equipment and power transmission equipment have developed towards high-voltage and large-capacity. With the rapid development of world science and technology, a variety of high-performance synthetic fibers have been developed and produced and applied to the paper industry, especially The application of aramid insulating paper is the most common and successful.

Due to the special use of insulating paper, it must have some characteristics different from other paper types, mainly including mechanical properties, electrical properties and thermal stability.

Mechanical behavior:

Insulating paper will be affected by various external forces during use. For example, the insulating paper used in high-voltage and large-capacity generators must be able to withstand high mechanical stress caused by high-speed rotation, starting and stopping, and sudden short circuits, so higher mechanical properties are required. , Mainly including tensile strength and elongation at break.

Thermal stability:

Thermal stability is a very important indicator of insulating paper and a major factor in the aging of low-voltage insulation, which determines its service life. Under normal operating conditions, the electric field strength has only a slight influence on the insulation aging process. Insulating paper used in a relatively high temperature environment for a long time will become brittle due to thermal aging, and gradually lose its mechanical and electrical properties.

Electrical performance:

Insulating paper is widely used in electrical equipment, so it needs to meet certain electrical properties. The electrical properties of insulating paper refer to its polarization, conductivity, dielectric loss and breakdown characteristics under the action of an electric field.

The properties of insulating paper are interrelated and cannot be viewed in isolation. In the process of selecting and developing materials, it is necessary to comprehensively balance the advantages and disadvantages of various materials. In order to produce insulating paper with good electrical properties, it is necessary to avoid the presence of metal ions and other impurities, bubbles, and moisture during the production process, and the insulating paper should have high uniformity.