Low viscosity HPMC :HPMC 400 is mainly used for self-leveling mortar, but generally imported.
Reason: The viscosity is low, although the water retention is poor, but the leveling is good, and the mortar density is high.
Medium and low viscosity:hydroxypropyl methylcellulose HPMC 20000-40000 is mainly used for tile adhesive, caulking agent, anti-cracking mortar, thermal insulation bonding mortar, etc.
Reason: good workability, less water addition, high mortar compactness.
1. What is the main purpose of hydroxypropyl methylcellulose (HPMC)?
——A: HPMC is widely used in building materials, coatings, synthetic resins, ceramics, medicine, food, textiles, 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.
2. There are several types of hydroxypropyl methylcellulose (HPMC), and what is the difference in their uses?
——Answer: 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 and has no real dissolution. After about 2 minutes, the viscosity of the liquid gradually increased, forming a transparent viscous colloid. Heat-dissolving products, when encountering cold water, can be quickly dispersed in hot water, and disappear in hot water. When the temperature drops to a certain temperature (our company’s product is 65 degrees Celsius), the viscosity slowly appears until it forms a transparent viscous colloid. 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.
3. What are the dissolution 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) Put the required amount of hot water in the container and heat it to about 70°C. 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.
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, 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. ]
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 of the good products have good whiteness. (2) 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. (3) 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 it . The permeability of the vertical reactor is generally good, and the horizontal reactor is worse, but it cannot be said that the quality of the vertical reactor is better than that of the horizontal reactor, and there are many factors that determine the product quality. (4) Specific gravity: the larger the specific gravity, the heavier the better. The specific gravity is large, generally because the hydroxypropyl content in it is high, and the hydroxypropyl content is high, the water retention is better.
5. The amount of hydroxypropyl methylcellulose (HPMC) in putty powder?
——Answer: The amount of HPMC used in practical applications varies depending on the climate, temperature, local ash calcium quality, the formula of putty powder and the “quality required by customers”. Generally speaking, it is between 4 kg and 5 kg. For example, most of the putty powder in Beijing is 5 kg; most of the putty powder in Guizhou is 5 kg in summer and 4.5 kg in winter;
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, the viscosity is higher, and the relative water retention is better. When the viscosity exceeds 100,000, the effect of viscosity on water retention is Not much.
7. 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. High viscosity, water retention, relatively (rather than absolute) better, and high viscosity, better use in cement mortar.
8. What are the main raw materials of hydroxypropyl methylcellulose (HPMC)?
—— A: The main raw materials of hydroxypropyl methylcellulose (HPMC): refined cotton, methyl chloride, propylene oxide, other raw materials include flake alkali, acid, toluene, isopropanol, etc.
9. What is the main role of HPMC in the application of putty powder, and is there any chemistry?
——Answer: HPMC has three functions of thickening, water retention and construction in putty powder. Thickening: Cellulose can be thickened to suspend, keep the solution uniform and consistent, and resist sagging. Water retention: Make the putty powder dry slowly, and assist the reaction of ash calcium under the action of water. Construction: Cellulose has a lubricating effect, which can make the putty powder have good workability. HPMC does not participate in any chemical reaction and only plays an auxiliary role. Adding water to the putty powder and putting it on the wall is a chemical reaction. Because of the formation of new substances, take the putty powder on the wall off the wall, grind it into powder, and use it again. It will not work, because new substances (calcium carbonate) have been formed. ) up. The main components of ash 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 Ash calcium in water and air Under the action of CO2, calcium carbonate is generated, while HPMC only retains water and assists the better reaction of ash calcium, and does not participate in any reaction itself.
10. HPMC is non-ionic cellulose ether, so what is non-ionic?
- Answer: In layman’s terms, non-ions are substances that do not ionize in water. Ionization refers to the process by which an electrolyte is dissociated into free-moving charged ions in a specific solvent (such as water, alcohol). For example, sodium chloride (NaCl), the salt eaten every day, dissolves in water and ionizes to produce freely moving sodium ions (Na+) that are positively charged and chloride ions (Cl) that are negatively charged. That is, when HPMC is placed in water, it does not dissociate into charged ions, but exists in the form of molecules.
Post time: Oct-17-2022