Polymer, also known as synthetic resin, is the main component of plastics. In addition, in order to improve the performance of plastics, various auxiliary materials such as fillers, plasticizers, lubricants, stabilizers, colorants, etc. need to be added to the polymer in order to become high-performance plastics.

1. Synthetic resin

Synthetic resin is the most important component of plastics, with a content generally ranging from 40% to 100%. Due to its high content and the fact that the properties of resin often determine the properties of plastics, resin is often regarded as a synonym for plastic. For example, mixing polyvinyl chloride resin with polyvinyl chloride plastic, phenolic resin with phenolic plastic. In fact, resin and plastic are two different concepts. Resin is an unprocessed raw polymer used not only in the manufacturing of plastics, but also as a raw material for coatings, adhesives, and synthetic fibers. Except for a very small portion containing 100% resin, the vast majority of plastics require the addition of other substances in addition to the main component resin.

2. Filler

Fillers, also known as fillers, can improve the strength and heat resistance of plastics and reduce costs. For example, adding wood powder to phenolic resin can greatly reduce costs, making phenolic plastic one of the cheapest plastics and significantly improving mechanical strength. Fillers can be divided into two categories: organic fillers and inorganic fillers. The former includes wood powder, rags, paper, and various textile fibers, while the latter includes glass fiber, diatomaceous earth, asbestos, carbon black, etc.

3. Plasticizer

Plasticizers can increase the plasticity and softness of plastics, reduce brittleness, and make plastics easy to process and shape. Plasticizers are generally high boiling point organic compounds that are miscible with resins, non-toxic, odorless, and stable to light and heat. The most commonly used are phthalates. For example, when producing polyvinyl chloride plastic, if a large amount of plasticizer is added, soft polyvinyl chloride plastic can be obtained. If no or less plasticizer is added (dosage<10%), hard polyvinyl chloride plastic can be obtained.

4. Stabilizer

In order to prevent the decomposition and damage of synthetic resins by light and heat during processing and use, and to extend their service life, stabilizers should be added to the plastic. Commonly used include stearates, epoxy resins, etc.

5. Colorants

Colorants can give plastics various bright and beautiful colors. Organic dyes and inorganic pigments are commonly used as colorants.

6. Lubricants

The function of lubricants is to prevent plastic from sticking to metal molds during molding, while also making the surface of plastic smooth and beautiful. Commonly used lubricants include stearic acid and its calcium magnesium salts.

In addition to the above additives, flame retardant, foaming agent, antistatic agent, etc. can also be added into the plastic to meet different use requirements.

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