Classification and Application Fields of Unsaturated Polyester Resin
Polyester resin is a class of polymers formed by the esterification and condensation reactions of diols/polyols and diacids/polyacids. It can be divided into saturated polyester resin and unsaturated polyester resin. Saturated polyester resin is mainly used as a plasticizer and film for coil coating in the field of thermosetting. Unsaturated polyester resin is generally formed by the condensation of unsaturated diacids and diols, or diacids and unsaturated diols, into a linear polymer compound. After dilution with a crosslinking agent (usually styrene), it forms a resin solution with a certain viscosity. It is a rapidly developing sub-product with strong functionality in polyester resin, characterized by strong chemical resistance, good electrical properties, and flexible and fast curing methods, mainly used in composite materials, coatings, adhesives, and other products.

According to the application, unsaturated polyester resin can be divided into reinforced unsaturated polyester resin and non-reinforced unsaturated polyester resin.

Reinforced unsaturated polyester resin, also known as fiberglass resin, is used as a matrix material with glass fiber and its products as reinforcement to manufacture fiberglass composite materials. Fiberglass composite materials are lightweight, hard, non-conductive, stable in performance, mechanically strong, have little recycling, and are corrosion-resistant. They can be applied to lightweight engineering, environmental protection engineering, rail transit, wind energy, energy-saving construction, and other fields. In addition, fiber-reinforced composite materials can be divided into carbon fiber, boron fiber, aramid fiber, aluminum oxide fiber, or silicon carbide fiber composite materials according to different reinforcing fibers.

Non-reinforced unsaturated polyester resin can be mixed with inorganic fillers to produce gel coats, coatings, and other products, which can be applied to decorative coatings, casting crafts, artificial stone, and other fields.

Relationship between the Unsaturated Polyester Resin Industry and Upstream and Downstream Industries
The main raw materials for the unsaturated polyester resin industry are styrene, maleic anhydride, phthalic anhydride, ethylene glycol, propylene glycol, diethylene glycol, etc. Unsaturated polyester resin production enterprises need to rely on large-scale petrochemical enterprises in the upstream to ensure a long-term stable supply of raw materials. On the one hand, the price fluctuation of upstream raw materials will directly affect the production cost of unsaturated polyester resin. On the other hand, the sufficient, stable, and timely supply of upstream raw materials will affect the normal production and operation of unsaturated polyester resin production enterprises.

The downstream industry mainly consists of manufacturing enterprises of artificial stone, fiberglass composite materials, and crafts. With the continuous development of China's economy, the steady progress of industrialization, urbanization, and agricultural modernization, the prosperity of the downstream industry has also driven the development of the unsaturated polyester resin industry.

Demand for Unsaturated Polyester Resin Industry
As one of the largest and most widely used varieties in the thermosetting resin industry, unsaturated polyester resin can be used as a matrix material to produce composite materials through glass fiber reinforcement and other methods, which are used in various fields such as wind energy, rail transit, automotive, and green building. On the other hand, it can be mixed with inorganic fillers to produce various non-reinforced material products, which are used in artificial stone, coatings, casting crafts, and other fields.

Based on different matrix materials, composite materials are further divided into metal matrix composites and non-metal matrix composites. Unsaturated polyester resin, as one of the main matrix materials for non-metal matrix composites, is gradually used to replace traditional wooden materials and metal alloy materials and has been widely applied in various fields of modern industry.

(1) Wind Energy

With the development of the wind energy industry towards large-scale installed capacity and large-scale single machine capacity, the quality requirements for key components such as blades and nacelles are increasing. Resin-based composite materials, due to their lightweight, high strength, seismic resistance, and fatigue resistance, have realized the replacement of traditional metal materials. At present, the matrix resin used in the production of wind turbine blades is mainly epoxy resin, vinyl ester resin, and unsaturated polyester resin, accounting for about 36% of the cost structure of wind turbine blades.

Under the double carbon background, China's renewable energy development has entered a fast track, and wind power has become the third largest source of electricity generation in China after coal and hydropower. According to data released by the National Energy Administration, by the end of 2022, China's wind power installed capacity was 365 million kilowatts.

According to the "14th Five-Year Plan for Renewable Energy Development," by 2025, China's wind power generation will double compared to 2020. With the support of national industry policies, China's wind power industry has great development potential, and the application prospect of matrix resin in the wind power field is broad.

(2) Rail Transit

With the progress of society and the improvement of people's living standards, residents' travel has higher requirements for the convenience and comfort of rail transit. In the body of rail transit vehicles, resin-based composite materials, due to their corrosion resistance, weather resistance, flame retardancy, low toxicity, low smoke emission, light weight, high strength, and large rigidity, play an important role in the overall safety and comfort of vehicles, weight reduction and noise reduction, and reducing maintenance costs.

Resin-based composite materials are mainly used in the rail transit field for body structural parts, front-end crash energy absorption devices, carriage structural floors, car doors and windows, bogies, carriage interior panels, sanitary facilities, etc.

According to the railway statistics bulletin released by the National Railway Administration, by the end of 2021, the national railway operating mileage reached 150,000 kilometers, with a compound annual growth rate of 3.65% from 2015 to 2021; the national railway passenger car ownership was 78,000 vehicles, with a compound annual growth rate of 3.09% from 2015 to 2021; the national train set was 33,221 vehicles, with a compound annual growth rate of 11.12% from 2015 to 2021.

With the rapid development of China's rail transit towards high speed, heavy load, and safety and comfort, and with more rail transit projects going global, the unique properties of resin-based composite materials such as high strength, low shrinkage, flame retardancy, and lightweight will be applied on a larger scale with the development of China's rail transit industry.

(3) Automobile

Resin-based composite materials, due to their lightweight, high strength, and wear resistance, can partially replace traditional metal automotive components, thereby reducing vehicle weight, improving aerodynamic performance, and reducing energy consumption. At present, resin-based composite materials are mainly used in exterior parts such as bumpers, spoilers, and splash boards, interior parts such as seats, dashboards, and door inner panels, functional structural parts such as cylinder cover caps, air filter cover caps, and engine intake manifolds, as well as body materials.

The rapid development of China's industrialization and urbanization, as well as the improvement of people's living standards, provide strong support for the development of China's automotive industry. According to statistics from the China Association of Automobile Manufacturers, China's vehicle production reached 27.02 million vehicles in 2022, and has been growing positively since 2020 despite the slowdown of the global economy.

At present, resin-based composite materials have been widely used in China's automotive field. In the future, with the continuous improvement of new materials, new technologies, and new processes, resin-based composite materials will become an effective way to alleviate the contradiction between the increasing number of vehicles in China and energy saving and environmental protection in the field of automotive lightweight and energy-saving.

(4) Green Building

The "14th Five-Year Plan for Building Energy Conservation and Green Building Development" issued by the Ministry of Housing and Urban-Rural Development clearly states that by 2025, all new buildings in urban areas will be green buildings, the energy utilization efficiency of buildings will be steadily improved, the energy consumption structure of buildings will be gradually optimized, and the growth trend of building energy consumption and carbon emissions will be effectively controlled, basically forming a green, low-carbon, and circular construction development mode, laying a solid foundation for the carbon peak in the construction field before 2030.

Resin-based composite materials have excellent mechanical properties, strong plasticity, and excellent performance in heat insulation, sound insulation, light transmission, and decoration. They are of great significance for reducing the self-weight of buildings, improving the functionality of buildings, achieving energy saving and emission reduction, and improving economic benefits. At present, they are widely used in new types of exterior wall materials, insulation materials, waterproof sealing materials, and decorative materials. With the rapid development of the green building industry in the future, the market demand for composite materials using unsaturated polyester resin will be further released.

Future Development Trends of China's Unsaturated Polyester Resin Market
Driven by the development of the terminal industries such as transportation, construction, and electronics, the unsaturated polyester resin industry has a broad development prospect in China in the future. China's unsaturated polyester resin industry is in a critical period of integration and transformation, gradually showing industry characteristics of scale, regionalization, automation, standardization, and regulation.

(1) Scale

China's annual production of unsaturated polyester resin has been