1. There are several types of hydroxypropyl methylcellulose HPMC, and what is the difference between their uses?
Answer: Hydroxypropyl methylcellulose HPMC can be divided into instant type and hot-melt type. Instant-type products disperse quickly in cold water and disappear into the water. At this time, the liquid has no viscosity, because HPMC is only dispersed in water, there is no real dissolve. After about 2 minutes, the viscosity of the liquid gradually increased, forming a transparent viscous colloid. Hot-dissolving products, when encountering cold water, can quickly disperse 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. The hot-melt type can only be used in putty powder and mortar. In liquid glue and paint, clumping phenomenon will occur and 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, without any contraindications.
2. What is the main purpose of hydroxypropyl methylcellulose (HPMC)?
A: HPMC is widely used in building materials, coatings, synthetic resins, ceramics, medicine, food, textile, agriculture, cosmetics, tobacco and other industries. HPMC can be divided into: construction grade, food grade and pharmaceutical grade according to the purpose. At present, most of the domestic products are construction grade. In the construction grade, the amount of putty powder is very large, about 90% is used for putty powder, and the rest is used for cement mortar and glue.
3. What are the dissolving methods of hydroxypropyl methylcellulose HPMC?
Answer: 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 rapidly dissolved when cooled. Two typical methods are described as follows:
1), add 1/3 or 2/3 of the required amount of water in the container, and heat it to 70 ° C, according to the method of 1), disperse HPMC, 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 HPMC powder with a large amount of other powdery substances, mix thoroughly with a mixer, and then add water to dissolve, then HPMC can be dissolved at this time without clumping together, because there is only a little HPMC in every tiny little corner. The powder will dissolve immediately in contact with water. ——This method is used by putty powder and mortar manufacturers. [Hydroxypropyl methylcellulose (HPMC) is used as thickener and water-retaining agent in putty powder mortar.
2), put the required amount of hot water in the container, and heat it to about 70 ℃. The hydroxypropyl methylcellulose was gradually added with slow stirring, initially the HPMC floated on the surface of the water, and then gradually formed a slurry, which was cooled with stirring.
4. How to judge the quality of hydroxypropyl methylcellulose (HPMC) simply and intuitively?
Answer: (1) Specific gravity: the larger the specific gravity, the heavier the better. larger, usually because
(2) Whiteness: Although whiteness does not determine whether HPMC is easy to use, and if a whitening agent is added in the production process, it will affect its quality. However, most of the good products have good whiteness.
(3) Fineness: The fineness of HPMC is generally 80 mesh and 100 mesh, and 120 mesh is less. Most of the HPMC produced in Hebei is 80 mesh. The finer the fineness, the better in general.
(4) Transmittance: Put hydroxypropyl methylcellulose (HPMC) in water to form a transparent colloid, and check its transmittance. The higher the transmittance, the better, indicating that there are less insoluble substances in . The permeability of vertical reactors is generally good, and that of horizontal reactors is worse, but it cannot be said that the quality of vertical reactors is better than that of horizontal reactors, and there are many factors that determine the quality of products. The hydroxypropyl content in it is high, and the hydroxypropyl content is high, the water retention is better.
5. What are the main technical indicators of hydroxypropyl methylcellulose (HPMC)?
Answer: Hydroxypropyl content and viscosity, most users care about these two indicators. The higher the hydroxypropyl content, the better the water retention. Viscous, water-holding, relatively (instead of
6. What is the appropriate viscosity of hydroxypropyl methylcellulose (HPMC)?
Answer: Putty powder is generally 100,000 yuan, and the mortar is more demanding, and it is easy to use at 150,000 yuan. Moreover, the most important role of HPMC is to retain water, followed by thickening. In putty powder, as long as the water retention is good and the viscosity is lower (70,000-80,000), it is also possible. Of course, if the viscosity is higher, the relative water retention is better. When the viscosity exceeds 100,000, the effect of viscosity on water retention is Not much. Absolutely) is also better, and the viscosity is high, and it is better to use in cement mortar.
7. What are the main raw materials of hydroxypropyl methylcellulose (HPMC)?
Answer: The main raw materials of hydroxypropyl methylcellulose (HPMC): refined cotton, methyl chloride, propylene oxide, other raw materials include flake alkali, acid, toluene, isopropanol, etc.