The viscosity index of hydroxypropyl methylcellulose is a very important index. The viscosity does not represent the purity. The viscosity of cellulose HPMC depends on the production process. Different use environments should choose cellulose HPMC with different viscosities, not the higher the viscosity of cellulose HPMC, the better! What is right is right √
Viscosity Control
1. High-viscosity hydroxypropyl methylcellulose cannot produce very high cellulose only by vacuuming and replacing with nitrogen. Generally, the production of high-viscosity cellulose in China cannot be controlled. However, if a trace oxygen measuring instrument can be installed in the kettle, the production of viscosity can be controlled artificially.
Use of associative agents
2. In addition, considering the replacement speed of nitrogen, and at the same time, it is very easy to produce high-viscosity products no matter how airtight the system is. Of course, the degree of polymerization of the refined cotton is also crucial. If that doesn’t work, do it by hydrophobic association. There are domestic associative agents in this regard. What kind of associative agent is selected has a great influence on the performance of the final product.
Hydroxypropyl content
3. The residual oxygen in the reactor leads to the degradation of cellulose and the reduction of molecular weight, but the residual oxygen is limited. It is not difficult to make high viscosity as long as the broken molecules are reconnected. However, the water saturation rate is also closely related to the content of hydroxypropyl. Some factories only want to reduce the cost and price, and are unwilling to increase the content of hydroxypropyl, so the quality cannot reach the level of similar foreign products.
other factors
4. The water retention rate of the product has a great relationship with hydroxypropyl, but for the entire reaction process, it also determines its water retention rate, the effect of alkalization, the ratio of methyl chloride and propylene oxide, and the concentration of alkali. And the ratio of water to refined cotton determines the performance of the product.
Post time: Oct-19-2022