The resin produced by polycondensation reaction of binary or polycarboxylic acid and binary or polyhydric alcohol is called polyester resin, which can be divided into two categories: saturated polyester and unsaturated polyester.
Unsaturated polyester resins are generally linear polymers formed by polycondensation of unsaturated dibasic acids, saturated dibasic acids, and glycols, and contain repeated unsaturated double bonds and ester bonds in the resin molecule. Since the unsaturated polyester resin obtained in this way is in a solid or semi-solid state and cannot be cross-linked well to become a body structure product with good performance, it must be diluted by the cross-linking agent styrene in the later stage of production to form a certain Viscosity resin solution. In fact, the unsaturated polyester resin used is this resin solution. The curing agent and other substances are added during use, so that the double bond in the styrene monomer and the unsaturated polyester molecule undergoes free radical copolymerization, and the final cross-link becomes a body shape. Structural resin.
It can be seen that the unsaturated polyester resin is a thermosetting resin, and the reaction process of forming a body structure is: di one step generates a linear molecule through the polycondensation reaction of a dibasic acid and a diol; The free radical copolymerization reaction between the double bond of the resin and the crosslinking agent results in a bulk structure. This different reaction stage is achieved by different functional groups and different reaction mechanisms, which is the characteristic of unsaturated polyester resin synthesis and curing.