Mainstream Production Process: Emulsion Polymerization
Raw Material Preparation
The core monomers are butadiene and acrylonitrile, precisely proportioned with an acrylonitrile content of 18%–50%.
Auxiliary agents include emulsifiers, initiators, molecular weight regulators, electrolytes, and terminators.
Polymerization Reaction
Cold polymerization: Reaction temperature of 5–15°C; utilizes a continuous production process and is currently the dominant global production method.
Hot polymerization: Reaction temperature of 30–50°C; typically a batch process with a lower share of total production.
Reaction duration is 8–12 hours; a terminator is added to stop the reaction once the target conversion rate is reached.
Post-processing
Degassing: Unreacted butadiene is recovered via reduced-pressure flash evaporation, and free acrylonitrile is removed under vacuum, enabling monomer recycling.
Coagulation: Electrolytes (such as brine) are added to destabilize the latex system, causing rubber particles to precipitate and coagulate.
Drying: After water washing and mechanical dewatering (squeezing), the product is processed in a dryer to reduce moisture content to below 1%, yielding the final solid nitrile rubber product.
