Production process knowledge of hydroxypropyl methylcellulose

Shandong chuangyao Biotechnology Co., Ltd. specializes in the production and operation of various types of hydroxypropyl methyl cellulose. Hydroxypropyl methyl cellulose, also known as hydroxypropyl methylcellulose and cellulose ether HPMC, is a highly pure cotton cellulose as raw material, treated with alkali solution at 35-40 ℃ for 30 minutes, pressing, crushing the cellulose, aging at 35 ℃ to make the average degree of polymerization of the obtained alkali fiber in the required range. Put the alkali fiber into the etherification kettle, etherify at 50-80 ℃ for 5h, and the maximum pressure is about 1.8MPa. Then the material is washed in hot water at 90 ℃ to expand the volume, then dehydrated by centrifuge, and then repeatedly washed to neutral.

Hydroxypropyl methyl cellulose (HPMC) is a non-ionic cellulose ether hydroxypropyl methyl cellulose (HPMC). The raw material can be refined cotton or wood pulp. It is necessary to crush it before or during alkalization. Crushing is to destroy the aggregate structure of cellulose raw material by mechanical energy, so as to reduce the crystallinity and polymerization degree, increase its surface area, and improve the reaction reagent The accessibility and chemical reaction ability of three hydroxyl groups on the glucose ring of cellulose macromolecules were studied.

Hydroxypropyl methyl cellulose (HPMC) can be used as raw material to produce oil, which can realize the utilization of total sugar, improve the utilization rate of raw materials, reduce the residual amount of substrate in fermentation broth, and reduce the cost of wastewater treatment. This characteristic of HPMC is conducive to the optimization of batch, feed batch and continuous fermentation processes, avoiding a series of problems such as the control of medium composition and dilution rate; At the same time, it is beneficial to control the fermentation process. Hydroxypropyl methyl cellulose (HPMC) is similar to other water-soluble ethers, and can be used as film-forming agent, thickener, emulsifier and stabilizer in latex coatings and water-soluble resin coatings. It has good wear resistance, uniform coating property and adhesion, and improves surface tension, acid-base stability and metal pigment compatibility. Hydroxypropyl methyl cellulose (HPMC) has a good effect as a thickener of white water-based polyvinyl acetate coatings. The degree of substitution of cellulose ether was increased, and the resistance to bacteria was also strong.

Although the principle of etherification of HPMC is not complicated, it can be divided into alkali, raw material crushing and alkalization. Etherification, solvent recovery, centrifugal separation, washing and drying all involve a lot of key technologies and rich knowledge. For different products, each environment has the closest control conditions, such as temperature, time, pressure and material flow control. Auxiliary equipment and control instrument are favorable guarantee for stable product quality and reliable production system. Generally speaking, non-ionic cellulose ether is in water, will not ionize the material. Ionization refers to the process that electrolyte is dissociated into charged ions which can move freely in specific solvents (such as water and alcohol). For example, sodium chloride (NaCl), a daily salt, is dissolved in water and ionized to produce free moving sodium ions (Na +) and chloride ions (CL) which are positively charged and negatively charged. In other words, HPMC in water does not dissociate into charged ions, but exists in the form of molecules.

The purity of hydroxypropyl methylcellulose in thermal insulation mortar of engineering construction directly affects the guarantee of engineering construction quality. In the production process of hydroxypropyl methylcellulose, the residual oxygen in the reactor leads to the degradation of hydroxypropyl methyl cellulose, and the molecular weight is reduced. However, the residual oxygen is limited, as long as the broken molecules are re connected, it is not very difficult. However, the water saturation rate is also closely related to the content of hydroxypropyl group. Some factories only want to reduce the cost and price, rather than increase the content of hydroxypropyl, so the quality can not reach the level of similar products abroad. The water retention rate of hydroxypropyl methylcellulose is closely related to hydroxypropyl group, but it also determines its water retention rate for the whole reaction process. The properties of the product are determined by the alkalization effect, the ratio of chloromethane to propylene oxide, the concentration of alkali and the ratio of water to refined cotton.

Quality of raw materials. The effect of alkalization. Some hydroxypropyl methyl cellulose is as cloudy as milk after being dissolved. Some are milky white, some are yellow and some are clear and transparent. If you want to solve the problem, adjust it from the above points. Sometimes acetic acid can seriously affect the light transmittance. It is best to use acetic acid after dilution. The most important factor is whether the reaction is stirred evenly, and whether the system ratio is stable (some materials have unstable moisture content, such as the solvent used for recycling). In fact, many factors are affecting it. If the equipment is stable and the operators are well trained, the production should be stable. The light transmittance will not exceed ± 2%, and the substitution uniformity of substituents should be well controlled. Instead of uniformity, the light transmittance will be better. Hydroxypropyl methyl cellulose is widely used, especially in the field of building materials in recent years.

Source: Shandong chuangyao Biotechnology Co., Ltd http://www.cyhuagong.com