The main chain contains -NHCOO- repeating structural unit of a type of polymer. The English abbreviation PU. It is polymerized by isocyanate (monomer) and hydroxyl compound. Because of the strong polar urethane group, it is insoluble in non-polar group It has good oil resistance, toughness, abrasion resistance, aging resistance and adhesion. Different raw materials can be used to make materials suitable for a wide temperature range (-50～150℃), including elastomers, thermoplastic resins and Thermosetting resin. It is not resistant to hydrolysis at high temperature, nor is it resistant to alkaline media.
"Polyester" is a type of macromolecular compound that contains ester bonds and is distinguished from resins such as "phenolic" and "epoxy". This macromolecular compound is produced by the condensation reaction of dibasic acid and glycol. When this polymer compound contains unsaturated double bonds, it is called unsaturated polyester. This unsaturated polyester is dissolved in a polymerizable monomer (generally styrene) and becomes a viscous liquid. At the time, it is called unsaturated polyester resin (English name Unsaturated Polyester Resin abbreviated as UPR). Therefore, unsaturated polyester resin can be defined as a dibasic acid and dihydric alcohol containing unsaturated dibasic acid or dibasic A viscous liquid made from linear polymer compounds of alcohol dissolved in monomers (usually styrene).
Unsaturated polyester resin is a kind of thermosetting resin, when under the action of heat or initiator, it can be cured into an insoluble and infusible polymer network polymer. However, the mechanical strength of this polymer is very low and cannot satisfy Most of the requirements used, when reinforced with glass fiber, can become a composite material, commonly known as "Fiber Reinforced Plastics" (English name Fiber Reinforced Plastics, referred to as FRP). The mechanical strength of "FRP" and other aspects of performance compared with resin casting A great improvement.