Plastic composition

- Mar 16, 2019-

Synthetic resin

Synthetic resin is the most important component of plastics, and its content in plastics is generally 40% to 100%. Because of the high content and the nature of the resin often determines the nature of the plastic, resin is often considered synonymous with plastic. For example, a mixture of polyvinyl chloride resin and polyvinyl chloride plastic, phenolic resin and phenolic plastic. In fact, resin and plastic are two different concepts. Resin is a raw, unprocessed polymer that is used not only in the manufacture of plastics, but also as a raw material for coatings, adhesives, and synthetic fibers. In addition to a small part of plastic containing 100% resin, most plastics, in addition to the main component resin, need to add other substances.


Fillers, also known as fillers, increase the strength and heat resistance of plastics and reduce costs. For example, the addition of wood powder to phenolic resin can greatly reduce the cost, making phenolic plastic one of the cheapest plastics, while also significantly improving mechanical strength. Fillers can be divided into organic fillers and inorganic fillers, such as wood powder, rags, paper and various fabric fibers, such as glass fiber, diatomaceous earth, asbestos, carbon black and so on.


Plasticizers increase the plasticity and softness of plastics, reduce brittleness, and make plastics easy to process. Plasticizers are generally miscible, non-toxic, odorless, high-boiling organic compounds that are stable to light and heat, and the most commonly used are phthalates. For example, when producing polyvinyl chloride plastic, if you add more plasticizer, you can get soft PVC plastic. If you don't add or add plasticizer (<10%), you can get rigid PVC plastic. .


In order to prevent the synthetic resin from being decomposed and destroyed by light and heat during processing and use, and prolonging the service life, a stabilizer is added to the plastic. Commonly used are stearates, epoxy resins and the like.


Colorants give plastics a variety of bright, beautiful colors. Organic dyes and inorganic pigments are commonly used as colorants.


The role of the lubricant is to prevent the plastic from sticking to the metal mold during molding, and to make the surface of the plastic smooth and beautiful. Commonly used lubricants are stearic acid and its calcium and magnesium salts.