The light transmittance of hydroxypropyl methylcellulose is mainly affected by the following points:
1. The quality of raw materials.
Second, the effect of alkalization.
3. Process ratio
4. Proportion of solvent
5. The effect of neutralization
Some products are cloudy like milk after they are dissolved, some are milky white, some are yellowish, and some are clear and transparent… To solve the problem, adjust from the following points. Sometimes acetic acid can seriously affect the light transmittance. It is best to use acetic acid after dilution. The biggest influence is whether the reaction is stirred evenly and whether the system ratio is stable (some materials have moisture and the content is unstable, such as the solvent used for recycling). In fact, many factors are affecting. If the equipment is stable and the operators are well trained, the production should be very stable. The light transmittance will not exceed the range of ±2%, and the substitution uniformity of the substituent groups must be well controlled. Instead of uniformity, light transmittance would definitely be fine.
Factors affecting the viscosity of hydroxypropyl methylcellulose:
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 measuring instrument can be installed in the kettle, the production of its viscosity can be controlled artificially.
made. 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. 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. 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, alkali concentration and water retention rate for the entire reaction process. The ratio to refined cotton determines the performance of the product.