What is the difference between saturated polyester resin and unsaturated polyester resin?

In the field of materials science, polyester resin is an important polymer compound widely used in various fields. Among them, saturated polyester resin and unsaturated polyester resin are two different types of polyester resin.

They are similar but have significant differences in performance, use and production processes. This article will compare and understand these two polyester resins to help readers better understand them.

1. Definition and characteristics

From a structural point of view, they are all derivatives of polyester resin. The main difference between saturated polyester resin and unsaturated polyester resin is that saturated polyester resin does not have double bonds in the main chain, while unsaturated polyester resin has double bonds in the main chain.

Saturated polyester resin SPR

Saturated polyester resin (oil-free alkyd resin), as the name suggests, is a polyester resin with high saturation, decomposition resistance and high hardness. Saturated polyester resin is formed by the reaction of polybasic acid and polyol.

Its molecular structure is stable and not easily affected by the external environment, so it has excellent durability, weather resistance, protection, flexibility and hardness. In addition, saturated polyester resin has strong versatility and can be widely used in construction (steel, non-stick pans, PET coils), automobiles (metal baking paint such as automobile paint), electrical appliances, chemicals (coatings, inks, adhesives) and other fields .

Unsaturated polyester resin UPR

In contrast, unsaturated polyester resin has the characteristics of high unsaturation, good cross-linking, and good flexibility.

Unsaturated polyester resin is basically made by joining certain chemicals together in straight lines to form a polymer. This joining process, called condensation polymerization, occurs when specific types of acids and alcohols are combined. They react together at temperatures between 190 and 220°C until the desired consistency or acidity is reached. Once the reaction is complete, we add a special liquid called a vinyl monomer to the hot mixture, creating a thick solution called an unsaturated polyester resin.

It is a thermosetting resin that solidifies into an insoluble, infusible polymer network under the action of heat or an initiator. Although this polymer has low mechanical strength, when reinforced with glass fibers, it can form a composite material, commonly known as "glass fiber reinforced plastics." FRP has the characteristics of light weight and high strength. Its density is only 1/4-1/5 of steel, but its strength is not low, even exceeding that of section steel, duralumin and fir.

2. Production technology and application

Saturated polyester resin

The production process of saturated polyester resin is relatively simple, and the raw materials are abundant and easy to obtain. Can be cured at room temperature and has good process performance. In the construction industry, saturated polyester resin is mainly used for steel plate coatings due to its excellent decorative properties, protective properties, durability and construction properties. In addition, it can also be used in ink and other fields.

Finally, due to its economical nature, it is also suitable for coil coatings with general requirements. Depending on the resin properties and structure, it can be used as topcoat, primer and backcoat for coil coatings. Among them, polyester surface layer is the most used. painting.

Saturated polyester resin

The production of unsaturated polyester resin requires specific chemical reactions. Due to its cross-linking properties, products with different properties can be prepared by adding different fillers and reinforcing materials. Unsaturated polyester resin is mainly used to prepare artificial marble, bathroom equipment, furniture, etc. In addition, unsaturated polyester resin also plays an important role in high-tech fields such as aviation, aerospace, rockets, and missiles.

There are significant differences between saturated polyester resin and unsaturated polyester resin in terms of properties, uses and production processes.

Although unsaturated polyester resin is a non-toxic resin, it still belongs to Class III dangerous goods. Due to current export restrictions, iSuoChem® does not mainly promote such products. We currently mainly sell saturated polyester resin. However, if you have any questions about unsaturated polyester resin and saturated polyester resin, please feel free to consult us.