The domestic organic silicon fine chemical research and development team has recently completed the full process technical breakthrough of the continuous synthesis process of low acid value ethyl silicone oil. Multiple key details have been achieved in the core reaction and post-treatment links, completely solving the industry pain points of high catalyst residue and large acid value fluctuations in traditional acid condensation processes.


In terms of reaction system design, the team abandoned the intermittent acid catalyzed polymerization mode that has been used for decades and for the first time used magnesium aluminum doped cerium phosphotungstate solid superacid as the main catalyst, combined with a three-stage gradient temperature controlled polymerization reactor: the first stage completed the ring opening prepolymerization of ethylsiloxanes at a low temperature of 45 ℃ to avoid molecular chain breakage caused by local overheating; The second stage is heated to 75 ℃ to complete the medium chain growth, and the reaction time is precisely controlled by a real-time online viscosity monitoring system to stabilize the molecular weight distribution width within the range of 1.08-1.12; The third stage enters the low-temperature maturation stage at 60 ℃, allowing residual monomers to fully participate in polymerization and significantly reducing the load of subsequent de boiling.


In the post-processing stage, the team independently developed a multi-stage gradient filtration coupled vacuum flash evaporation process: the polymerized material is first filtered through a two-stage nano ceramic membrane with decreasing pore size gradient, which increases the removal efficiency of solid superacid catalyst to 99.7% without the need for additional water washing process to avoid wastewater generation; Subsequently, it entered the three-stage series vacuum flash evaporation system and gradually removed D3-D10 ring small molecules in a high vacuum environment of 180 ℃ and -0.009MPa. The final product, ethylsilanol acid, had a stable value controlled below 0.01mg/KOH/g, far lower than the average level of 0.05mg/KOH/g for conventional products in the industry. The transparency of the product reached 99.2%, and the 24-hour thermal weight loss at 200 ℃ was only 0.12%, fully meeting the raw material access requirements for high-end beauty and medical grade products. At present, the process has completed continuous trial production of a 3000L reaction kettle, with viscosity deviation between batches controlled within ± 2%, and production efficiency increased by 230% compared to traditional batch processes.