1. How many types of hydroxypropyl methyl cellulose (HPMC) are there? What is the difference between them?
HPMC can be divided into instant soluble and hot soluble. Instantly soluble products, dissipate quickly in cold water and disappear in water. At this point, the liquid has no viscosity because HPMC is just dispersed in water and does not dissolve. After about 2 minutes, the viscosity of the liquid gradually increases and forms a clear viscous gel. The heat soluble product can disperse rapidly in hot water and disappears in hot water. As the temperature drops to a certain temperature, the viscosity gradually appears until a transparent viscous gel is formed.
Hot melt type can only be used in putty powder and mortar. In liquid glues and paints, caking will occur and cannot be used. Quick-soluble type is widely used in putty powder and mortar as well as liquid glue and paints.
2. How can the quality of hydroxypropyl methyl cellulose (HPMC) be easily and visually determined?
(1) Specific gravity: The higher the specific gravity, the better the quality.
(2) Whiteness: Most quality products have good whiteness. Except for those with whitening agents. Whitening agents can affect the quality.
(3) Fineness: The finer the fineness, the better the quality. The fineness of our HPMC is generally 80 mesh and 100 mesh, 120 mesh is also available.
(4) Transmittance: Put HPMC into water to form a transparent gel and observe the transmittance. The greater the transmittance, the less insoluble material. Vertical reactor usually has better transmittance and horizontal reactor has poorer transmittance, but this does not mean that the production quality of vertical reactor is better than other production methods. There are many factors that determine the product quality in horizontal reactor, high hydroxypropyl content, high hydroxypropyl content and best water retention.
3. What are the reasons for blistering of putty powder when HPMC is applied to putty powder?
HPMC is used in putty powder as a thickening agent, water retention agent and washing aid. It is not involved in any reaction.
Causes of foaming: 1. Too much water. 2. The bottom layer is not dry and scraping a layer on the top layer, which is also prone to foaming.
4. What are the main uses of hydroxypropyl methyl cellulose (HPMC)?
HPMC is widely used in construction materials, coatings, synthetic resin, ceramics, medicine, food, textile, agriculture, cosmetics, tobacco, etc. HPMC can be divided into construction grade, food grade and medicine grade according to its usage. Currently, most domestic production in China is in the construction stage. At the construction level, the amount of putty powder is large, about 90% is putty powder, and the rest is cement mortar and tile adhesive.
