Amidst the wave of upgrading high-end manufacturing and new materials industries, polyimide (PI), the "crown jewel of polymer materials," has become a key foundational material in strategic sectors such as semiconductor packaging, aerospace, and flexible electronics, thanks to its high and low temperature resistance (-269°C to 400°C), excellent dielectric properties, and mechanical strength. However, the traditional PI industry has long faced two major bottlenecks: First, dependence on imported raw materials (the import dependency of the core monomers, pyromellitic dianhydride (PMDA) and 4,4'-diaminodiphenyl ether (ODA), once reached 65%). The synthesis process requires the use of highly polar organic solvents (such as N,N-dimethylacetamide (DMAc), resulting in high VOC emissions. Second, the product's limited functionality: conventional PI has a relatively high dielectric constant (ε≈3.5-4.0) in high-frequency communications scenarios. Its transmittance (<85%) and flex resistance in flexible displays fail to meet high-end requirements, hindering its application in emerging fields.

To address these pain points, the industry has developed a three-pronged technological innovation system: "raw materials, processes, and functionality." On the raw material side, domestic companies have achieved breakthroughs in new monomer synthesis technologies through molecular design. The development of fluorinated dianhydride monomers (such as 6FDA) and silicon-containing diamine monomers has not only broken the foreign monopoly but also reduced the dielectric constant of polyimide (PI) to below 2.8 (meeting the requirements of 5G high-frequency communications) and increased its transmittance to over 90% (suitable for flexible OLED substrates). Furthermore, progress has been made in the development of bio-based monomers. Using furandicarboxylic acid, produced from fermented straw, as a raw material, the bio-based polyimide (PI) synthesized has a 42% lower carbon footprint than traditional petrochemical-based PI, and the conversion rate has reached 88% in the pilot stage.

Green innovation in polymerization processes is also crucial. Traditional solution polymerization processes consume large amounts of organic solvents, and subsequent film formation requires high-temperature desolventization (energy consumption accounts for 35% of total production energy consumption). Today, melt polymerization processes, through the introduction of new catalysts (such as organic phosphonates), have lowered reaction temperatures from 280°C to 220°C, eliminating the need for organic solvents and reducing VOC emissions by over 95%. Aqueous suspension polymerization, using water as the dispersion medium and combined with ultrasound-assisted dispersion, has improved the uniformity of PI resin particle size distribution to 92%, boosting subsequent processing efficiency by 30%. A chemical company has built a 30,000-ton/year high-performance PI production line using melt polymerization, reducing energy consumption per unit product by 28% compared to traditional processes and reducing organic solvent consumption by 12,000 tons annually.

Functional customization has expanded the application boundaries of PI. In the semiconductor field, by compounding nano-boron nitride (h-BN) into a polyvinyl chloride (PI) matrix, a highly thermally conductive PI composite material (with a thermal conductivity of 25 W/(m·K), 50 times that of ordinary PI) has been produced. This composite material is used as a heat dissipation substrate for chips in TSMC's 7nm process chip packaging. In the aerospace field, carbon fiber-reinforced PI composite materials (with a carbon fiber content of 30%) have a tensile strength of 1200 MPa and a temperature resistance of up to 350°C. They are used in engine door components for domestically produced large aircraft. In the field of flexible electronics, transparent PI films modified with surface coatings (such as a SiO₂ anti-scratch layer) have a flex resistance of over 100,000 cycles, making them the core substrate material for BOE's flexible OLED screens. Currently, my country's high-performance polyimide (PI) industrialization has entered a critical phase of "import substitution and high-end breakthroughs." The domestic PI market has grown from 8.5 billion yuan in 2018 to 21 billion yuan in 2024. The market share of domestically produced high-end PIs in semiconductor packaging has increased from 5% to 35%. A high-frequency, low-dielectric PI developed by one company has already passed Huawei's 5G base station certification. In the future, with the advancement of AI-assisted monomer molecular design (which can shorten the development cycle of new PIs by 60%) and continuous production processes (with production capacity increased to 100,000 tons per year), high-performance PIs will further develop towards "lower dielectric constants, higher thermal conductivity, and fully bio-based" characteristics. This will not only support the independent and controllable development of China's high-end manufacturing industry chain, but will also occupy a core position in the global PI market, injecting new momentum into the high-quality development of the new chemical materials industry.