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 suitable is right.
Viscosity Control
1. In the production of high-viscosity hydroxypropyl methylcellulose, only vacuuming and nitrogen replacement can not produce very high cellulose. Generally, the production of high-viscosity cellulose in China cannot be controlled. However, if a trace oxygen meter can be installed in the kettle, the production of its viscosity can be artificially controlled.
Association agent use
2. In addition, considering the replacement speed of nitrogen, it is easy to produce high-viscosity products no matter how airtight the system is. Of course, the degree of polymerization of refined cotton is also crucial. If that doesn’t work, then do it with hydrophobic association. There are association agents in this area in China. What kind of association agent to choose has a great influence on the performance of the final product.
Hydroxypropyl content
3. Residual oxygen in the reactor leads to degradation of cellulose and lower molecular weight. However, if the residual oxygen is limited, as long as the broken molecules are reconnected, it is not difficult to make high viscosity. However, the saturation rate has a lot to do with the content of hydroxypropyl. Some factories only want to reduce the cost and price, but 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 it also determines its water retention rate, alkalization effect, ratio of methyl chloride and propylene oxide, and alkali concentration for the entire reaction process. Both the ratio of water and refined cotton determine the performance of the product.
Post time: Apr-03-2023