1. What is the main application of hydroxypropyl methylcellulose (HPMC)?
HPMC is widely used in construction 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 construction grade, putty powder is used in a large amount, about 90% is used for putty powder, and the rest is used for cement mortar.
2. What is the smell of hydroxypropyl methylcellulose (HPMC)?
The HPMC produced by the solvent method uses toluene and isopropanol as solvents. If the washing is not very good, there will be some residual smell.
3. What are the dissolution methods of hydroxypropyl methylcellulose (HPMC)?
Hot water dissolution method: Since HPMC does not dissolve in hot water, HPMC can be evenly dispersed in hot water at the initial stage, and then quickly dissolves when cooled. Two typical methods are described as follows:
1) Put the required amount of hot water into the container and heat it to about 70°C. The hydroxypropyl methylcellulose was gradually added under slow stirring, initially the HPMC floated on the surface of the water, and then gradually formed a slurry, which was cooled under stirring.
2), add 1/3 or 2/3 of the required amount of water into the container, and heat it to 70°C, disperse HPMC according to the method of 1), and prepare hot water slurry; then add the remaining amount of cold water to hot water 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 agglomeration, because there is only a little HPMC in every tiny corner Powder, will dissolve immediately when in contact with water. ——Putty powder and mortar manufacturers are using this method. [Hydroxypropyl methylcellulose (HPMC) is used as a thickener and water retention agent in putty powder mortar. ]
4. How to judge the quality of hydroxypropyl methylcellulose (HPMC) simply and intuitively?
(1) Whiteness: Although whiteness cannot determine whether HPMC is easy to use, and if whitening agents are added during the production process, it will affect its quality. However, most of the good products have good whiteness.
(2) Fineness: The fineness of HPMC generally has 80 mesh and 100 mesh, and 120 mesh is less. Most HPMC produced in Hebei is 80 mesh. The finer the fineness, generally speaking, the better.
(3) Light transmittance: put hydroxypropyl methylcellulose (HPMC) into water to form a transparent colloid, and look at its light transmittance. The greater the light transmittance, the better, indicating that there are less insolubles in it. . The permeability of vertical reactors is generally good, and that of horizontal reactors is worse, but it does not mean that the quality of vertical reactors is better than that of horizontal reactors, and product quality is determined by many factors.
(4) Specific gravity: The larger the specific gravity, the heavier the better. The specificity is large, generally because the content of hydroxypropyl group in it is high, and the content of hydroxypropyl group is high, the water retention is better.
5. What is the difference between the cold-water instant type and the hot-soluble type of hydroxypropyl methylcellulose in the production process?
The fast-dispersion type of HPMC is surface-treated with glyoxal, and it disperses quickly in cold water, but it does not really dissolve. It only dissolves when the viscosity increases. The instant type has no surface treatment with glyoxal. If the amount of glyoxal is large, the dispersion will be fast, but the viscosity will increase slowly, and if the amount is small, the opposite will be true.
6. What is the appropriate viscosity of hydroxypropyl methylcellulose (HPMC)?
Putty powder is generally 100,000 yuan, and the requirements for mortar are higher, and 150,000 yuan is required for easy use. Moreover, the most important function of HPMC is water retention, followed by thickening. In the putty powder, as long as the water retention is good and the viscosity is low (70,000-80,000), it is also possible. Of course, the higher the viscosity, the better the relative water retention. When the viscosity exceeds 100,000, the viscosity will affect the water retention. Not much anymore.
7. What are the main technical indicators of hydroxypropyl methylcellulose (HPMC)?
Hydroxypropyl content and viscosity, most people are concerned about these two indicators. Those with high hydroxypropyl content generally have better water retention. The one with high viscosity has better water retention, relatively (not absolutely), and the one with high viscosity is better used in cement mortar.
8. What are the main raw materials of hydroxypropyl methylcellulose (HPMC)?
The main raw materials of hydroxypropyl methylcellulose (HPMC): refined cotton, methyl chloride, propylene oxide, and other raw materials, caustic soda, acid, toluene, isopropanol, etc.
9. What is the main function of the application of HPMC in putty powder, and does it happen chemically?
In the putty powder, HPMC plays three roles of thickening, water retention and construction.
Thickening: Cellulose can be thickened to suspend and keep the solution uniform up and down, and resist sagging.
Water retention: make the putty powder dry slowly, and assist the ash calcium to react under the action of water.
Construction: Cellulose has a lubricating effect, which can make the putty powder have good construction.
Adding water to the putty powder and putting it on the wall is a chemical reaction, because new substances are formed. If you remove the putty powder on the wall from the wall, grind it into powder, and use it again, it will not work because new substances (calcium carbonate) have been formed. ) too.
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 is in water and air Under the action of CO2, calcium carbonate is generated, while HPMC only retains water, assisting the better reaction of ash calcium, and does not participate in any reaction itself.
10. HPMC is a non-ionic cellulose ether, so what is non-ionic?
In layman’s terms, non-ions are substances that do not ionize in water. Ionization refers to the process in which an electrolyte is dissociated into charged ions that can move freely in a specific solvent (such as water, alcohol). For example, sodium chloride (NaCl), the salt we eat every day, dissolves in water and ionizes to produce freely movable sodium ions (Na+) that are positively charged and chloride ions (Cl) that are negatively charged. That is to say, when HPMC is placed in water, it will not dissociate into charged ions, but exist in the form of molecules.
11. What is the gel temperature of hydroxypropyl methylcellulose related to?
The gel temperature of HPMC is related to its methoxy content, the lower the methoxy content, the higher the gel temperature.
12. Is there any relationship between the drop of putty powder and HPMC?
The powder loss of putty powder is mainly related to the quality of ash calcium, and has little to do with HPMC. The low calcium content of gray calcium and the improper ratio of CaO and Ca(OH)2 in gray calcium will cause powder loss. If it has something to do with HPMC, then if HPMC has poor water retention, it will also cause powder loss.
13. What is the difference between the cold-water instant type and the hot-soluble type of hydroxypropyl methylcellulose in the production process?
The fast-dispersion type of HPMC is surface-treated with glyoxal, and it disperses quickly in cold water, but it does not really dissolve. It only dissolves when the viscosity increases. The instant type has no surface treatment with glyoxal. If the amount of glyoxal is large, the dispersion will be fast, but the viscosity will increase slowly, and if the amount is small, the opposite will be true.
Post time: Apr-25-2024