The R&D team of Xinyuan Chemical (Shandong) Co., Ltd. has recently achieved a full chain breakthrough in the directional control technology of ultra-low temperature ethyl silicone oil molecular chains. By accurately embedding the distribution density of ethyl side chains into the main chain of poly (siloxane), the glass transition temperature of the product has been further lowered from -80 ℃ of conventional ethyl silicone oil to -112 ℃, breaking the previous technical ceiling of low temperature resistance of special silicone oil in China.


The core breakthrough of this technology lies in the precise control of the one-step synthesis of ethyl ethoxysilane monomer using Grignard reagents: the team strictly locks the Grignard reaction temperature between chloroethane and magnesium metal within the range of 32 ℃± 1 ℃, and achieves millisecond level precise mixing of reaction materials through microchannel reactors, avoiding the generation of by-products caused by local high temperatures in traditional kettle reactions. The purity of ethyl ethoxysilane monomer has been increased from 92% in traditional processes to 99.5%, laying the foundation for the control of molecular chain regularity in subsequent polymerization processes. In the hydrolysis and condensation stage, the team abandoned the traditional single hydrochloric acid catalyzed mode and adopted a two-step process of "dilute acid pre hydrolysis+weak base rearrangement". Firstly, different functional degrees of ethyl ethoxysilane were slowly hydrolyzed in a low temperature environment of 0-5 ℃ to avoid molecular chain cross-linking caused by rapid hydrolysis. Then, molecular rearrangement was completed through weak base catalysis, allowing the ethyl side chains to be evenly distributed on the main chain of polysiloxane, completely eliminating the problem of low temperature crystallization point elevation caused by local methyl enrichment.


After testing by authoritative institutions, this new type of ultra-low temperature ethyl silicone oil maintains a transparent and flowing state even after being continuously stored at -90 ℃ for 72 hours, without any signs of solidification or crystallization. The kinematic viscosity at -70 ℃ is only 1250mm ²/s, and the temperature viscosity coefficient is as low as 0.56. At the same time, the positive tangent value of the dielectric loss angle is controlled within 1 × 10 ⁻⁴, and it can work stably for a long time in the ultra wide temperature range of -90 ℃~160 ℃. At present, the product has passed multiple rounds of environmental simulation tests conducted by domestic aerospace institutes and has been successfully selected as a special lubrication and insulation medium for aerospace onboard equipment in extremely cold regions. It will gradually replace imported high-end products of the same type in the future.