The quality of hydroxypropyl methylcellulose produced by horizontal kettle and vertical kettle
Hydroxypropyl methylcellulose is a cellulose ether derivative, and its production currently has two process routes: horizontal kettle dry method and vertical kettle solvent method;
1. The horizontal production process of the horizontal kettle dry process is an early-developed production process. Its main production process is kneading and alkalizing cotton fibers in liquid alkali, and then passing through etherification agent for etherification. This dry production process is not conducive to the diffusion and penetration of the etherifying agent, so the etherification reaction time is short, the efficiency is relatively low, the cost is relatively low, and the reaction is unstable, the uniformity is poor, the side reactions are many, and the quality of the obtained product is relatively poor.
2. The production process of the vertical kettle solvent method is to alkalinize and etherify cotton fibers in an inert organic solution, thus increasing the diffusion and penetration rate of the reagents, which is conducive to mass and heat transfer in the reaction process and makes the reaction stable. The etherification is uniform, the etherification agent consumes little, and the etherification efficiency is high, the cost is relatively high, and the resulting product has high quality and stability. At present, the advanced production process of the solvent method is mostly used at home and abroad. Different companies use different solvents, and the reaction mechanism is basically the same.