Unsaturated polyester products were still in the research and development stage before the Second World War. During the war, it was first used in military aviation. In 1941, the United States used propylene alcohol to obtain unsaturation to produce propylene-based resins, and maleic acid and fumaric acid were used to obtain unsaturation to obtain polyester. The following year, a batch of polyester fiberglass reinforced plastic radomes were made with glass cloth reinforcement. They are light in weight, high in strength, good in microwave transmission, easy to manufacture, and quickly used in warfare, showing excellent performance.
After the war, unsaturated polyester was promoted to civilian use, and quickly spread to Western Europe, Japan, the former Soviet Union and countries around the world. After 1950, glass fiber reinforced plastic products have been the main use of unsaturated polyester, and paint base materials are still being used. After 1955, solvent-free paints were produced. In 1957, there should be a new breakthrough in the casting of polyester, which began to be used to produce "pearl" buttons. After 1959, it was used to manufacture artificial marble, artificial agate, and floor and pavement covering materials, which have been widely used.
After 1957, the molding and processing methods of polyester resins have been significantly improved, and bulk molding compounds (BMC, DMC) and sheet molding compounds (SMC) have emerged, enabling polyester products to achieve high rates, high quality, and low cost. Mass production. Especially when the automotive industry requires the use of lightweight, high-strength composite materials due to restrictions on fuel consumption, the demand for polyester sheet molding compounds has increased.