Factors affecting the purity of hydroxypropyl methylcellulose

In the building insulation mortar, the purity of hydroxypropyl methyl cellulose directly affects the quality of the construction quality, then what are the factors affecting the purity of hydroxypropyl methylcellulose? MICHEM answers this question for you.
In the production process of hydroxypropyl methylcellulose, the residual oxygen in the reactor causes degradation of hydroxypropyl methylcellulose, and the molecular weight is lowered, but the residual oxygen is limited, and it is not difficult to reconnect the broken molecules. However, the water saturation rate is also closely related to the content of hydroxypropyl groups. Some factories only want to reduce the cost and price, unwilling to increase the content of hydroxypropyl groups, so the quality does not reach the level of similar foreign products. The water retention rate of hydroxypropyl methylcellulose is closely related to hydroxypropyl, but it also determines its water retention rate, the effect of alkalization, the ratio of methyl chloride and propylene oxide for the whole reaction process. The concentration of alkali and the ratio of water to refined cotton determine the performance of the product.
There are many factors impact on the HPMC performance, such as the quality of the raw materials; the effect of alkalization; Process ratio, solvent ratio neutralization effect. Some hydroxypropyl methyl cellulose is dissolved to make it turbid like milk, some are milky white, some are yellow, and some are clear and transparent. To solve it, adjust from the above points. Sometimes acetic acid can seriously affect the light transmittance, better use the acetic acid after dilution. the maximum effect is whether the mixing of the reaction is uniform, and the system ratio is stable (some materials have unstable water content, such as the solvent used for recycling), in fact, many factors are affecting. The production should be stable if possess high stability equipment and skilled operators. The light transmittance does not exceed ±2%, control the substitution uniformity of the substituent group. The light transmittance is definitely good only if the substituent group distribute equally.


Post time: Mar-20-2019