Yuan boards are typically thin, sheet-like materials formed by depositing fibers—made from plant, mineral, synthetic materials, or a combination thereof—on a papermaking machine via water or other mediums. Insulating paper boasts high tear resistance, low elongation, and excellent insulation properties, making it widely used as an insulating material in motors, cables, capacitors, and transformers. It is also a primary component in materials such as laminates, composites, and pre-impregnated materials used for insulation.

Due to the specialized applications of insulating paper, it must possess certain characteristics different from other types of paper, primarily including mechanical properties, electrical performance, and thermal stability.

Mechanical properties

Insulating paper is subject to various external forces during use, such as the high-speed rotation, start-stop operations, and sudden short-circuiting that generate significant mechanical stresses in generators with high voltage and large capacity. Therefore, it is required to have high mechanical properties, primarily including tensile strength and elongation at break.

2. Thermal Stability

Thermal stability is a crucial indicator for insulating paper, a primary factor in the formation of low-voltage insulation aging, and determines its service life. Under normal operating conditions, the electric field strength has only a slight impact on the insulation aging process. Insulating paper used for an extended period in a high-temperature environment will become brittle due to thermal aging, gradually losing its mechanical and electrical properties.

3. Electrical Performance

Insulating boards are widely used in electrical equipment, hence they must meet certain electrical properties. The electrical properties of insulating paper refer to its polarization, electrical conductivity, dielectric loss, and breakdown characteristics under the influence of an electric field.

Insulation board properties are interrelated; they cannot be viewed in isolation. During the selection and development of materials, it's crucial to comprehensively balance the pros and cons of various materials. Additionally, to produce insulation paper with excellent electrical properties, it is essential to minimize the presence of impurities like metal ions, as well as bubbles and moisture during the production process. The insulation paper must also exhibit high uniformity.