The effect of the odor of hydroxypropyl methylcellulose on quality
What are the effects of odor size on hydroxypropyl methylcellulose:
Synthesis of hydroxypropyl methyl cellulose: The refined cotton cellulose is treated with lye solution at 35-40 ℃ for half an hour, squeezed, cellulose is pulverized, and properly aged at 35 ℃, so that the obtained alkali fiber has an average degree of polymerization. within the desired range. Put the alkali fiber into the etherification kettle, add propylene oxide and methyl chloride in turn, and etherify at 50-80 ℃ for 5h, the pressure is about 1.8MPa. Then add an appropriate amount of hydrochloric acid and oxalic acid to the hot water at 90 ° C to wash the material to expand the volume. Dehydrate with a centrifuge. Wash until neutral, when the water content in the material is less than 60%, dry it with a hot air flow at 130°C to less than 5%.
The HPMC produced by the solvent method uses toluene and isopropanol as the solvent. If the washing is not good, there will be a slight residual odor. This is a problem of the washing process, and it does not affect the use and there is no problem, but in reality The hydroxypropyl methylcellulose produced by many manufacturers has a particularly strong odor and a pungent odor. The quality of this is definitely not enough.
Hypromellose is refined cotton that is rarely impregnated with liquid to obtain alkaline cellulose, and then adds solvent, etherifying agent, toluene and isopropanol to carry out etherification reaction. Not good, there will be smell, so users can use it with confidence.