HPMC construction-Questions and answers about hydroxypropyl methyl cellulose
1. What is the main purpose of hydroxypropyl methylcellulose (HPMC)?
——Answer: HPMC is widely used in construction materials, coatings, synthetic resins, ceramics, medicine, food, textile, agriculture, cosmetics, tobacco and other industries. HPMC can be divided into: building grade, food grade and medicine grade according to usage. At present, most of the production is construction grade. In the construction grade, the amount of putty powder is very large. About 90% is used for making putty powder, and the rest is used for cement mortar and glue.
2. Hydroxypropyl methyl cellulose (HPMC) is divided into several types, what is the difference between its uses?
——Answer: HPMC can be divided into instant type and hot melt type. Instant type products can disperse rapidly in cold water and disappear in the water. At this time, the liquid has no viscosity because HPMC is only dispersed in water and has no real dissolution. After about 2 minutes, the viscosity of the liquid gradually increased, forming a transparent viscous colloid. The hot-melt type product, in the presence of cold water, can disperse quickly in hot water and disappear in hot water. When the temperature drops to a certain temperature, the viscosity slowly appears until a transparent viscous colloid is formed. Hot melt type can only be used in putty powder and mortar. In liquid glue and paint, there will be clumping phenomenon, which cannot be used. The instant type has a wider range of applications. It can be used in putty powder and mortar, as well as in liquid glue and paint. There are no contraindications.
3. What are the dissolution methods of hydroxypropyl methyl cellulose (HPMC)?
——Answer: Hot water dissolution method: Because HPMC does not dissolve in hot water, the initial HPMC can be evenly dispersed in hot water, and then quickly dissolved during cooling. Two typical methods are described as follows:
1) Put the required amount of hot water in the container and heat to about 70℃. Hydroxypropyl methylcellulose was gradually added with slow stirring, and HPMC began to float on the surface of water, and then a slurry was gradually formed, and the slurry was cooled with stirring.
2). Add the required amount of 1/3 or 2/3 water to the container, and heat to 70 ℃, 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, the mixture was cooled after stirring.
Powder mixing method: Mix the HPMC powder with a large amount of other powdered materials, mix thoroughly with a blender, and then add water to dissolve, then the HPMC can be dissolved without clumping and agglomeration, because each small corner has only a little HPMC The powder will dissolve immediately in water. ——Putty powder and mortar manufacturers use this method. Hydroxypropyl methylcellulose (HPMC) is used as a thickener and water retention agent in putty powder mortar.