Views:3 Author:Site Editor Publish Time: 2020-09-23 Origin:Site
Regarding HPMC questions and answers
3. What are the dissolution methods of hydroxypropyl methylcellulose (HPMC)?
——Answer: Hot water dissolution method: Since HPMC does not dissolve in hot water, HPMC can be uniformly dispersed in hot water at the initial stage, and then quickly dissolve during cooling. Two typical methods are described as follows: 1), put in a container Fill in the required amount of hot water and heat to about 70°C. Gradually add hydroxypropyl methyl cellulose under slow stirring, start HPMC floating on the surface of water, and then gradually form a slurry, and cool the slurry under stirring. 2). Add 1/3 or 2/3 of the required amount of water into the container and heat it to 70°C. According to the method of 1), disperse HPMC to prepare hot water slurry; then add the remaining amount of cold water to hot water In the slurry, cool the mixture after stirring. Powder mixing method: mix HPMC powder with a large amount of other powdery materials, mix thoroughly with a blender, and then add water to dissolve, then HPMC can be dissolved at this time without clumping, because each tiny corner, there is only a little HPMC The powder will dissolve immediately when it meets water. ——Putty powder and mortar manufacturers use this method. [ Hydroxypropyl methylcellulose (HPMC) is used as a thickener and water-retaining agent in putty powder mortar. ] Organic solvent is the wet method: pre-disperse or moisten HPMC with an organic solvent, such as ethanol, ethylene glycol or oil, and then add water to dissolve, then HPMC can also be dissolved smoothly.
4. How to judge the quality of hydroxypropyl methylcellulose (HPMC) simply and intuitively?
——Answer: (1) Whiteness: Although whiteness cannot determine whether HPMC is easy to use, and if a brightener is added in the production process, it will affect its quality. However, most good products have good whiteness. (2) Fineness: The fineness of HPMC is generally 80 mesh and 100 mesh, 120 mesh is less, and most HPMC produced in Hebei is 80 mesh. The finer the fineness, the better in general. (3) Transmittance: Put hydroxypropyl methylcellulose (HPMC) in water to form a transparent colloid, and look at its transmittance. The greater the transmittance, the better, indicating that there are fewer insolubles inside. . The permeability of vertical reactors is generally good, while that of horizontal reactors is worse. (4) Proportion: The greater the proportion, the heavier the better. The high specificity is generally due to the high hydroxypropyl content in it, and the higher the hydroxypropyl content, the better the water retention.
5. How much is hydroxypropyl methyl cellulose (HPMC) in putty powder?
——Answer: The amount of HPMC used in actual applications varies depending on the climate, temperature, local ash calcium quality, formula of putty powder and "quality required by customers". Generally speaking, it is between 4 kg and 5 kg. For example, Beijing putty powder is mostly 5 kg; Guizhou is mostly 5 kg in summer and 4.5 kg in winter; Yunnan is relatively small, usually 3 kg-4 kg and so on.
To be continued...
Hydroxypropyl methyl cellulose is divided into two kinds of ordinary hot soluble cold water instantly soluble. Hydroxypropyl methyl cellulose uses are 1, Gypsum series In the gypsum series of products, cellulose ethers are mainly used to retain water and increase smoothness. Together they play a cer