Unsaturated polyester resin is a kind of thermosetting resin, which can be cured into an insoluble and infusible high molecular network polymer under the action of heat or initiator. However, the mechanical strength of this polymer is very low and cannot meet the requirements of most uses. When reinforced with glass fibers, it can become a composite material, commonly known as “glass fiber reinforced plastic” (FRP for short). Compared with the resin casting body, the mechanical strength and other aspects of “glass fiber reinforced plastic” have been greatly improved. This is the biggest advantage of unsaturated polyester resin. It can be cured at room temperature, formed under normal pressure, and has flexible process performance, especially suitable for large-scale and on-site manufacturing of FRP products. After curing, the overall performance of the resin is good, and the mechanical performance index is slightly lower than that of epoxy resin, but better than that of phenolic resin. Corrosion resistance, electrical properties and flame retardancy can meet the requirements by selecting the appropriate grade of resin. The resin is light in color and can be made into transparent products. The unsaturated polyester resin matrix used as composite material matrix at home and abroad is basically phthalic acid type (referred to as orthophthalic type), isophthalic acid type (abbreviated as isophthalic type), bisphenol A type and vinyl ester type, Halogenated unsaturated polyester resin, etc.

What are the advantages and disadvantages of unsaturated resin coatings
Its advantages: 1. It has good hardness, which can reach more than 3H. 2. The topcoat can make a high gloss. 3. Good wear resistance, alkali resistance and heat resistance. 4. High fullness. Disadvantages: 1. The workability is more complicated because initiators and accelerators need to be added to achieve curing. The amount of initiators and accelerators added depends on changes in temperature and humidity. In addition, initiators and accelerators cannot be transferred into the paint at the same time. Otherwise, it is easy to cause fire and there are strict requirements when mixing paint. 2. The adjusted paint has a short active period, and the adjusted paint must be used up within 25 days. product.

Factors Affecting Degree of Resin Curing
The curing of unsaturated polyester resin is a process in which linear macromolecules form a three-dimensional network through the action of a crosslinking agent, but the curing process cannot consume all active double bonds in the resin to achieve 100% curing. That is to say, the degree of curing of the resin is difficult to achieve completely. The reason is that in the late stage of the curing reaction, the viscosity of the system increases sharply, which hinders the diffusion of molecules. Generally, it can only be considered that the curing is complete when the properties of the material tend to be stable. The degree of curing of the resin has a great influence on the performance of FRP. The higher the curing degree, the mechanical properties and physical and chemical properties of FRP products can be fully exerted.
There are many factors affecting the degree of curing. The components of the resin itself, the amount of initiators and accelerators, curing temperature, post-curing temperature and curing time can all affect the degree of curing of polyester resins.

Features
Excellent process performance. This is the biggest advantage of unsaturated polyester resin. It can be cured at room temperature, formed under normal pressure, and has flexible process performance, especially suitable for large-scale and on-site manufacturing of FRP products.
After curing, the overall performance of the resin is good. The mechanical properties index is slightly lower than epoxy resin, but better than phenolic resin. Corrosion resistance, electrical properties and flame retardancy can meet the requirements by selecting the appropriate grade of resin. The resin is light in color and can be made into transparent products. There are many varieties, wide adaptability and low price.