The main component of injection mold parts used for medical devices is synthetic resin, and its content in plastics is generally 40% to 100%. Due to the large content and the properties of the resin often determine the properties of the plastic, people often regard the resin as a synonym for plastic. For example, polyvinyl chloride resin and polyvinyl chloride plastic, phenolic resin and phenolic plastic are confused. In fact, resin and plastic are two different concepts. Resin is a raw, raw polymer used not only to make plastics, but also as a raw material for coatings, adhesives and synthetic fibers. Except for a very small part of plastics that contain 100% resin, most plastics need to add other substances in addition to the main component resin.