Refined cotton—opening—alkalization—etherification—neutralization—separation—washing—separation—drying—crushing—packaging—finished HPMC product opening: The refined cotton is opened to remove iron and then crushed. The pulverized refined cotton is in the form of powder, with a particle size of 80 mesh and a transmittance of 100%. Otherwise, it is easy to coalesce together during the reaction process and reduce the etherification efficiency.
Alkalization: Add the powdered refined cotton after cotton opening to an inert solvent, and activate it with alkali and soft water to swell the lattice of refined cotton to facilitate the penetration of etherification agent molecules and improve the uniformity of etherification reaction. The alkali used for alkalization is a metal hydroxide or an organic alkali. The amount of alkali added (by mass, the same below) is 0.1-0.6 times that of refined cotton, the amount of soft water added is 0.3-1.0 times that of refined cotton; the inert solvent is a mixture of alcohol and hydrocarbon, and the amount of inert solvent added is 0.3-1.0 times that of refined cotton. 7 -15 times of that: The inert solvent can also be an alcohol with 3-5 carbon atoms (such as alcohol, propanol), acetone. It can also be aliphatic hydrocarbons and aromatic hydrocarbons; the temperature should be controlled within 0-35°C during alkalization; the alkalization time is about 1hr. The adjustment of temperature and time can be determined according to the material and product requirements.
Etherification: After alkalization treatment, under vacuum conditions, etherification agent is added for etherification, and the etherification agent is propylene oxide. In order to reduce the consumption of etherification agent, during the etherification process, the etherification agent is added in two times, the amount of the first addition is 1-3.5 times that of refined cotton, and the total amount of the two additions is 1.5-4 times that of refined cotton. times. After adding the etherifying agent for the first time, stir at ≤30°C for 45min-90min, then raise the temperature to 50-100°C for etherification for 1-5h, then cool down to ≤30°C , the second time to add etherification stirring, stirring time is 30-120min, and then heated to? ? ? Carry out etherification, the time is 1-4h, at this time, the refined cotton fully reacts with the etherification agent to generate hYDROXYPROPYL METHYLCELLULOSE HPMC.
Crushing and packaging: crushing and sieving the dried product of the present invention, the particle size of the HPMC product of the present invention after crushing and sieving is 40 mesh and the transmittance is 10096, or according to user needs. Then pack the HPMC.
Post time: Nov-24-2022