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In the second quarter of 2026, another key progress has been made in the field of domestic special organosilicon materials: a special pilot industrialization unit focusing on alicyclic epoxy modified silicone oil officially completed 7200 hours of continuous stable operation. The series of high-activity alicyclic epoxy silicone oil products produced have an alicyclic epoxy group molar content ranging from 8% to 35%, and a viscosity range of 150mm²/s to 12000mm²/s at 25°C. The long-term service temperature of the cured material reaches 280°C, and the space high-energy proton radiation resistance dose exceeds 1×10^6 rad. All extreme environment performance indicators have reached the international leading level. This achievement fills the domestic technical blank of high temperature resistant alicyclic epoxy silicone oil, and provides fully independent and controllable core materials for special sealing and coating in the extreme environment protection system of new-generation manned space engineering, deep space exploration aircraft and hypersonic aircraft.
Alicyclic epoxy modified silicone oil is a high-end segmented category in the field of epoxy modified silicone oil. Different from traditional glycidyl ether type epoxy silicone oil, its epoxy groups are directly bonded to the alicyclic structure, combining the high and low temperature resistance and radiation resistance of organosilicon materials, as well as the unique advantages of alicyclic epoxy such as high heat resistance, low shrinkage and UV aging resistance. It is a key basic material for special sealing, optical protective coating and structural part toughening modification in aerospace extreme environments. In the field of hypersonic aircraft, the aerodynamic heating temperature on the aircraft surface can reach above 300°C, accompanied by strong ultraviolet and particle radiation environments. Traditional organic sealing materials are prone to thermal decomposition, aging and cracking. The high temperature resistant sealing coating prepared from alicyclic epoxy silicone oil can work stably for a long time at 280°C, while resisting high-energy ray radiation in the space environment, fully meeting the protection requirements of hypersonic aircraft for long-term on-orbit flight. In the field of deep space exploration, the diurnal temperature difference on the lunar surface exceeds 300°C, accompanied by a large number of lunar dust particles and cosmic ray radiation. The optical lens protective film prepared from alicyclic epoxy silicone oil can maintain stable optical transmittance in the extremely wide temperature range of -196°C to 260°C, and has excellent anti-lunar dust adhesion performance, providing long-term protection for the optical loads of lunar rovers and deep space probes. In the field of new-generation manned spacecraft, alicyclic epoxy silicone oil, as the core toughening component of the cabin structural adhesive, can greatly improve the bonding reliability between the cabin metal and the composite material, and will not cause aging failure of the adhesive layer under long-term space environment.
Previously, the R&D and industrialization of domestic alicyclic epoxy silicone oil has long been in a blank state, and the core technical difficulties are concentrated in two directions: high-stability grafting of alicyclic epoxy groups and extreme environment performance regulation. When the traditional hydrosilylation process introduces alicyclic epoxy groups, epoxy ring-opening side reactions are very likely to occur, resulting in a significant decrease in the epoxy value of the product. At the same time, residual trace catalyst impurities will seriously reduce the radiation resistance of the material. The long-term service temperature of related products developed in the early stage in China is generally lower than 200°C, and the radiation resistance dose is less than 1×10^5 rad, which completely cannot meet the service requirements of aerospace extreme environments. For a long time, this type of product has been completely dependent on overseas imports. Not only the purchase price is more than 30 times that of ordinary electronic-grade epoxy silicone oil, but it is also subject to strict export controls. Some customized grades cannot even be obtained through normal trade channels, which has seriously restricted the R&D progress of China's new-generation aerospace equipment.
The industrialization technology system of alicyclic epoxy silicone oil that has achieved stable mass production this time has corely overcome two world-class industry problems. First, the non-noble metal catalyzed alicyclic epoxy directional grafting technology was pioneered. The R&D team abandoned the traditional platinum-based catalyst system, and independently developed a new non-noble metal coordination catalyst system. While completely avoiding platinum metal residue, the alicyclic epoxy ring-opening side reaction rate during the hydrosilylation process is controlled below 0.3%, which ensures the high epoxy activity and high stability of the product from the molecular structure level. Second, an extreme environment performance precise regulation platform was innovatively established. By introducing a specific proportion of phenyl and alicyclic epoxy groups into the polysiloxane molecular chain, the precise balance of the material's temperature resistance, radiation resistance and mechanical properties is realized. The long-term service temperature of the final cured product reaches 280°C, and after being irradiated by 1×10^6 rad high-energy protons, the tensile strength retention rate of the material is greater than 90%, and the mass loss rate is less than 0.2%. All extreme environment performance indicators have reached the international leading level.
At present, this independently developed alicyclic epoxy silicone oil has completed on-orbit environment simulation verification for more than 24 months in multiple aerospace core equipment fields. In the cabin sealing coating test of the new-generation manned spacecraft, the protective coating prepared with this product has no cracking or peeling after 1000 thermal shock cycles from -196°C to 260°C, and the adhesion retention rate of the coating reaches more than 95%. In the protective coating test of deep space exploration optical loads, after 1200 hours of ultraviolet radiation and lunar dust erosion test simulating the lunar surface environment, the visible light transmittance of the coating decreases by less than 0.5%, and the anti-lunar dust adhesion performance is improved by 70%. In the structural adhesive test of hypersonic aircraft, the structural adhesive modified with this product has a shear strength retention rate of more than 85% at high temperature of 280°C, fully meeting the structural bonding requirements of hypersonic aircraft for long-term flight.
With the gradual maturity of this technology and the subsequent implementation of the 1000-ton special production line, it is expected that by 2029, China will form a full-spectrum product system covering ordinary electronic-grade epoxy silicone oil and high-end alicyclic epoxy silicone oil. It will not only fully meet the independent supporting requirements of aerospace extreme environment equipment, but also further expand to emerging fields such as high-end special optical coatings and extreme environment sensor sealing, providing key material support for technological breakthroughs in multiple cutting-edge strategic fields in China.
