A resin produced by a polycondensation reaction of a binary or polycarboxylic acid and a binary or polyhydric alcohol is referred to as a polyester resin, and can be classified into two types of saturated polyesters and unsaturated polyesters.
The unsaturated polyester resin is generally a linear polymer obtained by polycondensation of an unsaturated dibasic acid, a saturated dibasic acid, and a diol, and contains a repeating unsaturated double bond and an ester bond in the resin molecule. Since the unsaturated polyester resin thus obtained is in a solid or semi-solid state, and does not crosslink well into a good-body structure product, it must be diluted with a cross-linking agent styrene at a later stage of production to have a certain Viscosity resin solution. In fact, the unsaturated polyester resin used is such a resin solution, and a substance such as a curing agent is added in the use to cause a radical copolymerization reaction between the styrene monomer and the double bond in the unsaturated polyester molecule, and finally the cross-linking becomes a body type. Structure of the resin.
It can be seen that the unsaturated polyester resin is a thermosetting resin, and the reaction process for forming a bulk structure is: the first step is to form a linear molecule by a polycondensation reaction of a dibasic acid and a glycol; and the second step is in the curing process. The bulk structure is obtained by a free radical copolymerization reaction between the double bonds of the resin and the crosslinking agent. This different reaction stage is achieved by different functional groups and different reaction mechanisms, and is characterized by the synthesis and solidification of unsaturated polyester resins.