Cellulose manufacturers explain the synthesis method of high-viscosity hydroxypropyl methylcellulose

Synthesis method of hydroxypropyl methylcellulose

A special method for synthesizing cellulose ethers uses nitrogen-protected alkalization and stepwise etherification methods to prepare hydroxypropyl methylcellulose with higher viscosity.

The steps are divided into:

1. Crush refined cotton to 0.2-0.4mm to obtain refined cotton fines;

2. Under nitrogen conditions, add the refined cotton fines described in step 1 to the mixed solution of sodium hydroxide solution (composed of sodium hydroxide and water) and binary organic solvent, and perform alkalization to obtain alkali cellulose ; The binary organic solvent is composed of toluene and isopropanol with a mass ratio of 5:1-10:1;

3. The alkali cellulose described in step (2) is added to the toluene solvent, and then isopropanol is added thereto, and then methyl chloride and propylene oxide are sequentially added to obtain a mixed reaction system; the toluene and isopropanol The mass ratio of 5:1-10:1, the mass ratio of methyl chloride and propylene oxide is 5:1-9:1; the total mass of toluene solvent and isopropanol is called toluene-containing solvent the quality of;

The above-mentioned mixed reaction system first performs low-temperature etherification at 30-50°C, and the reaction time is 40-50min; then heats up to 70-100°C for high-temperature etherification, and the reaction time is 40-50min to obtain higher viscosity hydroxypropyl methyl Cellulose (HPMC) finished product;

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