Process for the production of aqueous zinc chloride solution, one of the most suitable and economical solvent to spinning and polymerization of acrylic fiber, process for the stripping and recycling of the solvent, and process for the recovery of the residual acrylonitrile monomer from the polymerization system were developed.
The local commercial grade zinc chloride containing impure metals such as Fe, Mn, Al, Ca, Pb, Cu is dissolved in water.
The aqueous zinc chloride solution is reacted with water soluble persulfate, thereby Fe, Mn, Al, Ca were precipitated. After removal of precipitates through the filtration the remaining Pb, Cu ions in the solution are removed in packed bed of metal zinc.
The purified solution is adjusted the specific pH 3.5, the concentration 60%, and cupric ion content to control the molecular weight of polymer, thereby solvent is produced.
The diluted solvent, 30-35 wt % concentration, from the spinning system is stripped almost completely loss free to 60 wt % concentration in the evaporating system. The steam consumption in the evaporating system would be about $\frac{1}{4}$ of other process using nitric acid or thiocyanate. The stripped solvent is recycled to the polymerization system.
For the recovery of acrylonitrile monomer, the vapor from the debubbling unit is condensed in the condenser working with refrigerant. The monomer is separated from the water-monomer mixture and recycled to the polymerization system.
값싼 공업용 국산 염화아연을 수용액으로 만들어 정제하여 아크릴 섬유의 중합 및 방사에 적합한 용매를 제조하는 공정 개발에 성공 하였다.
중합후의 용매는 방사공정에서 물에 추출희석 되어 중량 백분율 농도 30 - 35% 가 되며 증발 조작으로써 60%로 농축 재순환 된다.
농축공정은 다른 아크릴 섬유공정과는 달리 용매회수가 거의 완벽하고 열소모가 적어 프로세스의 경제성을 살렸다.
또한 미반응 모노머의 회수는 별도의 복잡한 시스템을 쓰지 않고 냉각기와 진공시스템 만으로서 회수, 재순환 시켜 프로세스의 경제성을 살렸다.
