Thermosetting plastics refer to plastics that can be cured under heat or other conditions or have insoluble (melting) characteristics, such as phenolic plastics, epoxy plastics, etc. Thermosetting plastics are divided into formaldehyde cross-linked type and other cross-linked types. After thermal processing and molding, an infusible and insoluble cured product is formed, and the resin molecules are cross-linked into a network structure by a linear structure. Increased heat will decompose and destroy. Typical thermosetting plastics include phenolic, epoxy, amino, unsaturated polyester, furan, polysiloxane and other materials, as well as newer polydipropylene phthalate plastics. They have the advantages of high heat resistance and resistance to deformation when heated. The disadvantage is that the mechanical strength is generally not high, but the mechanical strength can be improved by adding fillers to make laminated materials or molded materials.
Thermosetting plastics made of phenolic resin as the main raw material, such as phenolic molded plastic (commonly known as Bakelite), are durable, dimensionally stable, and resistant to other chemical substances except strong alkalis. Various fillers and additives can be added according to different uses and requirements. For varieties that require high insulation performance, mica or glass fiber can be used as filler; for varieties that require heat resistance, asbestos or other heat-resistant fillers can be used; for varieties that require seismic resistance, various appropriate fibers or rubber can be used as fillers And some toughening agents to make high toughness materials. In addition, modified phenolic resins such as aniline, epoxy, polyvinyl chloride, polyamide, and polyvinyl acetal can also be used to meet the requirements of different applications. Phenolic resins can also be used to make phenolic laminates, which are characterized by high mechanical strength, good electrical properties, corrosion resistance, and easy processing. They are widely used in low-voltage electrical equipment.