Hydroxypropyl Methylcellulose HPMC common knowledge

1. What is the main purpose of HPMC?

This product is used as a thickener, dispersant, binder, excipient, oil-resistant coating, filler, emulsifier and stabilizer in the textile industry. It is also widely used in synthetic resin, petrochemical, ceramic, paper, leather, medicine, food and cosmetics industries.

2. What is the role of HPMC in interior wall putty powder?

HPMC has three functions: putty powder for inner wall, thickening, water-locking and construction. Concentration: Methyl cellulose can be concentrated by floating or aqueous solution to maintain uniform and consistent functions and prevent flowing and hanging. Locking water: The interior wall powder dries slowly, and the added lime calcium is reflected in the use of water. Engineering construction: Methyl cellulose has a wetting function, which can make the inner wall putty powder have a good engineering structure. HPMC does not participate in the change of all chemicals, but only participates in the replenishment. Inner wall putty powder, on the wall, is a chemical change, because there is a new chemical conversion, the inner wall putty powder is removed from the wall, milled, and reused , Because a new chemical substance (calcium bicarbonate) has been produced. The main components of gray calcium powder are: a mixture of Ca(OH)2, CaO and a small amount of CaCO3, CaO+H2O=Ca(OH)2 —Ca(OH)2+CO2=CaCO3↓+H2O gray calcium in water and air Under the action of CO2, calcium carbonate is formed, while HPMC only retains water and assists the better reaction of gray calcium, and it does not participate in any reaction itself.

3. How to judge the quality of HPMC simply and intuitively?

(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, 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 less insolubles inside. . The permeability of the vertical reactor is generally good, and the horizontal reactor is worse, but it does not mean that the quality of the vertical reactor is better than that of the horizontal reactor. The product quality is still determined by many factors. (4) Proportion: The larger 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.

4. What should be paid attention to when applying the viscosity and temperature of HPMC?

The viscosity of HPMC is inversely proportional to temperature, that is, the viscosity increases as the temperature decreases. We usually say that the viscosity of a product refers to the result of testing its 2% aqueous solution at a temperature of 20 degrees Celsius. In practical applications, in areas with a large temperature difference between summer and winter, it should be noted that it is recommended to use a relatively low viscosity in winter, which is more conducive to construction. Otherwise, when the temperature is low, the viscosity of the cellulose will increase, and the hand will feel heavy when scraped.

5. What are the dissolution methods of HPMC?

Hot water dissolution method: Since HPMC is not dissolved in hot water, HPMC can be uniformly dispersed in hot water at the initial stage, and then quickly dissolve when cooled. Two typical methods are described as follows: 1). Amount of hot water and heated to about 70°C. Gradually add hydroxypropyl methylcellulose with slow stirring, start HPMC floating on the surface of the water, and then gradually form a slurry, and cool the slurry with 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 and agglomerating, because each tiny corner, there is only a little bit of HPMC The powder will dissolve immediately when it meets water. -Putty powder and mortar manufacturers use this method. [Hydroxypropyl methyl cellulose (HPMC) is used as a thickener and water-retaining agent in putty powder mortar. ]

6. What is the dosage of HPMC added in putty powder?

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, the putty powder in decoration’>Beijing is mostly 5 kg; the putty powder in Guizhou is mostly 5 kg in summer and 4.5 kg in winter; Yunnan’s additive amount is relatively small, generally 3 kg-4 kg and so on.

Post time: Nov-13-2021