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!
1. Viscosity control
High-viscosity hydroxypropyl methylcellulose can’t produce very high cellulose only by vacuuming and nitrogen replacement in production. 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.
2. Use of association agent
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.
3. Hydroxypropyl content
The residual oxygen in the reactor causes the degradation of cellulose and the decrease of molecular weight, but 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.
4. Other factors
The water retention rate of the product has a great relationship with hydroxypropyl, but for the whole reaction process, it also determines its water retention rate, alkalization effect, ratio of methyl chloride and propylene oxide, alkali concentration and water retention. The ratio to refined cotton determines the performance of the product.
Post time: Apr-04-2023