Types of Synthetic Resins and Their Applications

Synthetic Resin is a class of artificially synthesized high molecular weight polymers. It is a type of resin that possesses inherent properties comparable to or exceeding those of natural resins. According to ASTM D883-65T, synthetic resin is defined as an organic substance that is solid, semi-solid, or pseudo (quasi) solid, often with a high molecular weight, which tends to flow under stress, typically has a softening or melting range, and exhibits a shell-like appearance upon fracture.

In practical applications, it is often used synonymously with polymers or even plastics, especially referring to basic materials generated by polymerization reactions from monomers, with no or very little additives. Additionally, it sometimes represents uncured flowable thermosetting polymer materials.

The three major synthetic materials in the world include synthetic resins, synthetic rubber, and synthetic fibers. Synthetic resin is the synthetic material with the highest production and consumption.

Types of Synthetic Resin

Synthetic resin industrial products can be divided into general-purpose resins and special-purpose resins.

General-purpose resins have high production volumes and low costs, and are generally used for general consumer goods or durable goods, with representative types including polyethylene, polypropylene, polyvinyl chloride, polystyrene, and the five major types of ABS synthetic resins.

Special-purpose resins are generally produced for specific applications, have lower production volumes, and higher production costs. For example, they can replace metals in machinery, electronics, and automotive industries. Engineering plastics fall into the category of special-purpose resins, with important examples including polyamide, polycarbonate, polyoxymethylene, polybutylene terephthalate, modified polyphenylene ether, and polytetrafluoroethylene. Another type of special-purpose resin is thermoplastic elastomers, which exhibit rubber-like elasticity and can be re-molded upon heating.

Based on chemical composition, synthetic resins can be roughly divided into two categories: one where the main chain consists solely of aliphatic carbon atoms, with general-purpose resins mostly belonging to this category; and another type of synthetic resin where the main chain contains oxygen, nitrogen, sulfur, and other elements in addition to carbon atoms, with most engineering plastics being composed of heterochain polymers.

Applications of Synthetic Resin

Synthetic resin's most important application is in the manufacturing of plastics. To facilitate processing and improve performance, additives are often added, sometimes directly used in molding. Hence, it often becomes synonymous with plastics. The content of synthetic resin in plastics generally ranges from 40-100%, and due to its high content and the fact that the properties of the resin often determine the properties of the plastic, people commonly refer to resin as a synonym for plastic. For example, polyvinyl chloride resin is often confused with polyvinyl chloride plastic and phenolic resin with phenolic plastic. However, 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. In contrast, plastic, except for a small portion containing 100% resin, mostly requires the addition of other substances besides the main component resin.

Synthetic resin is also the fundamental raw material for manufacturing synthetic fibers, coatings, adhesives, insulation materials, etc. Widely used resin concrete also uses synthetic resin as a binding material. Due to the apparent performance and cost advantages of synthetic resin compared to other competing materials, its applications permeate all aspects of the economy. Packaging is synthetic resin's largest market, followed by construction supplies. Electronics, electrical, and automotive are also significant application areas for synthetic resin. Other markets include furniture, toys, recreational items, household appliances, and medical supplies.