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What are the new types of unsaturated polyester resins? New types of unsaturated polyester resins are emerging one after another, and among them, the most noteworthy are the new unsaturated polyester imides and insulating materials. The continuous development of the electrical appliance industry imposes higher demands on insulating materials. How can we improve the properties of new unsaturated polyester resins, while maintaining the excellent processability of unsaturated polyesters? What are these new unsaturated polyester resins? New types of unsaturated polyester resins are emerging one after another, and among them, the most noteworthy are the new unsaturated polyester imides and insulating materials. The continuous development of the electrical appliance industry imposes higher demands on insulating materials. While maintaining the excellent processability of unsaturated polyesters, important research directions in this field involve improving their heat resistance and mechanical properties, enhancing their dimensional stability and chemical resistance as well as moisture absorption, and increasing their environmental compatibility. Introducing new functional groups into the molecular chain segments of existing unsaturated polyester imides is an important method for improving their properties. Introducing fluorine-containing groups into the molecular chains of unsaturated polyester imides and increasing the content of imide structures in them can significantly improve the thermal properties, mechanical properties, electrical properties, dielectric properties, and moisture absorption of unsaturated polyester imides. The Laboratory of High-Tech Materials at the Institute of Chemistry, Chinese Academy of Sciences, synthesized a new diol monomer containing an imine structure (BTGTB) and a diimino acid intermediate (BTTB), and prepared a new fluorinated unsaturated polyester imide resin. The results show that, while maintaining the excellent processability of unsaturated polyester, its heat resistance, mechanical properties, electrical properties, and chemical resistance have been improved. Moreover, unsaturated polyester imide resins with a high content of imide structures exhibit outstanding heat resistance. How to synthesize new fluorinated unsaturated polyester imide resins? The method for introducing fluorine-containing groups is by using fluorine-containing diamine monomers. The structure of the diamine monomer used can be seen from the relevant diagrams. Taking the first fluorinated diamine (6FAPB) as an example, intermediate iminols and imino acids are first prepared, and then the unsaturated polyester imine is synthesized. The imine alcohol intermediate monomer BGTB was prepared using the fluorinated diamine monomer 6FAPB, and further melt polycondensed with propylene glycol, isophthalic acid, and maleic anhydride to yield the unsaturated polyester imine BGTB-UPEI. The resulting pure resin is dissolved in acrylic diluents to form a homogeneous, stable unsaturated polyester imide resin with an appropriate viscosity, which then cures under certain conditions. The preparation of unsaturated polyester imide resin with a high imine content involves using the fluorinated diamine monomer 6FAPB to produce the imino acid monomer BTTB; BTTB is then further used in polycondensation with propylene glycol and maleic acid within a nitrogen-methylpiperidine framework to yield the unsaturated polyester imide UPEI-50. Experts from China’s unsaturated polyester resin industry state that the resulting resin is dissolved in acrylic-based diluents. By comparing the properties of the BGTB-UPEI insulating resin with those of the unmodified conventional unsaturated polyester resin (S-UP) after curing, it can be seen that, in terms of thermal properties, the glass transition temperature of the BGTB-UPEI-cured material is 26°C higher than that of S-UP, while its temperature at 5% weight loss is 30°C higher. Its coefficient of thermal expansion is 5.84x10-7/°C, which is lower than that of S-UP (6.81x10-7/°C). In terms of mechanical properties, the bending strength of BGTB-UPEI is 86.3 MPa, twice that of conventional unsaturated polyester resins; its elongation at break is 10.8%, which is nearly 59% higher than the 6.8% observed for conventional unsaturated polyester resins. Regarding electrical properties and moisture absorption, the unsaturated polyester imide exhibits excellent dielectric properties and low moisture absorption, with resistivity values of 0.36 and moisture absorption rates of 0.41% (after being immersed in water at 25°C for 24 hours), values similar to those of conventional unsaturated polyester resins. This is mainly attributed to the introduction of fluorine-containing groups, which improved the moisture absorption and dielectric properties of the unsaturated polyester imide. Meanwhile, the BGTB-UPEI insulating resin exhibits extremely excellent chemical resistance. In the experiments, experts recorded the mass changes of BGTB-UPEI and the conventional unsaturated polyester S-UP after curing, when immersed in various corrosive solutions for different periods of time. The results showed that after 54 days of immersion, the mass change of the cured unsaturated polyester imide resin was minimal in all solutions, and it was less than that of the conventional unsaturated polyester resin. Notably, BGTB-UPEI exhibits excellent properties such as strong resistance to alkalis, acids, and other strongly oxidizing solutions, which facilitates its use in more harsh environments. Experts introduced the research achievements on unsaturated polyester resins in this field by examining the properties of the fluorine-containing, high-imine-content UPEI-50 resin. The significant increase in imine content reduces the solubility of UPEI-50. UPEI-50 has low solubility in common unsaturated polyester resin diluents such as styrene, but it can dissolve in acrylic diluents, offering excellent processability. Table 3 provides a comprehensive comparison of the properties of UPEI-50 resin and the unmodified standard S-UP after curing. In terms of thermal properties, the glass transition temperature of UPEI-50 resin is much higher than that of S-UP, and its heat resistance meets the requirements for H-class insulation. In terms of mechanical properties, the flexural strength of UPEI-50 resin is twice that of S-UP ； The tensile strength is 33% higher than that of S-UP ； The flexural modulus of UPEI-50 is 41% higher than that of S-UP. In terms of electrical properties, UPEI-50 resin has a lower dielectric constant than S-UP, which is attributed to the significant increase in imine content and the introduction of numerous fluorine-containing groups. With the development of the aerospace industry and high-speed railways, there are increasing demands for the performance of composite materials. High-performance composite materials require high-performance resins as their matrix resins. Typically, high-performance resin matrices possess a special chemical structure and molding properties, offering high dimensional stability at high temperatures, excellent thermal oxidation stability, low moisture absorption, wear resistance, radiation resistance, and superior overall mechanical properties. Composites based on high-performance resins can be used as structural materials for long periods in harsh environments such as high-temperature oxidation and corrosion. To this end, we should pay attention to the R&D trends of major companies around the world, and by taking into account the needs of the domestic market, continuously develop new products to meet the growing demands of a wider range of customers.