Plastic Composition

The plastic we usually use is not a pure substance, it is formulated from many materials. Among them, high molecular polymers (or synthetic resins) are the main components of plastics. In addition, in order to improve the performance of plastics, various auxiliary materials are added to the polymers, such as fillers, plasticizers, lubricants, stabilizers, Colorants, etc., can become plastics with good performance.
1. Synthetic resin
Synthetic resin is the main component of plastics, 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.
2. Filling
Fillers, also called fillers, can improve the strength and heat resistance of plastics and reduce costs. For example, adding wood powder to phenolic resin can greatly reduce the cost, making phenolic plastic one of the cheapest plastics, and it can also significantly improve the mechanical strength. Fillers can be divided into organic fillers and inorganic fillers, the former such as wood powder, rags, paper and various fabric fibers, etc., and the latter such as glass fiber, diatomaceous earth, asbestos, carbon black, etc.
3. Plasticizer
Plasticizers can increase the plasticity and softness of plastics, reduce brittleness, and make plastics easier to process and shape. Plasticizers are generally high-boiling organic compounds that are miscible with resin, are non-toxic, odorless, and stable to light and heat. The most commonly used plasticizers are phthalates. For example, when producing polyvinyl chloride plastic, if more plasticizer is added, soft polyvinyl chloride plastic will be obtained. If no or less plasticizer is added (amount <10%), hard polyvinyl chloride plastic will be obtained. .
4. Stabilizer
In order to prevent synthetic resin from being decomposed and damaged by light and heat during processing and use, and to extend its service life, stabilizers should be added to the plastic. Commonly used ones include stearate, epoxy resin, etc.
5. Colorants
Colorants give plastics a variety of bright, beautiful colors. Organic dyes and inorganic pigments are commonly used as colorants.
6. Lubricant
The function 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 include stearic acid and its calcium and magnesium salts.
In addition to the above-mentioned additives, flame retardants, foaming agents, antistatic agents, etc. can also be added to plastics to meet different usage requirements.