Interpretation of hydroxypropyl methylcellulose HPMC problem
1. Hydroxypropyl methylcellulose HPMC is divided into several types. What is the difference in its use?
A: Hydroxypropyl methylcellulose HPMC can be divided into instant-dissolve and hot-dissolve, fast-dissolving products. When it is rapidly disperse in cold water, it disappears into the water. At this time, the liquid has no viscosity, because HPMC is only disperse in water, there is no real Dissolve.
About 2 minutes, the viscosity of the liquid gradually increase to form a transparent viscous colloid. The hot-melt type product, in the case of cold water, can be quickly disperse in hot water and disappear in hot water. When the temperature drops to a certain temperature, the viscosity gradually appears until a transparent viscous colloid is formed.
The hot-dissolve type can only be used in putty powder and mortar. In liquid glue and paint, there will be a phenomenon of clumping, which cannot be used. It is available in a wide range of applications, in putty powder and mortar, as well as in liquid glues and coatings. There are no contraindications.
2. What is the main use of hydroxypropyl methylcellulose HPMC?
A: HPMC is widely use in construction materials, coatings, synthetic resins, ceramics, medicine, food, textiles, agriculture, cosmetics, tobacco and other industries. HPMC can be divide into: building, food and pharmaceutical. At present, most of the domestically produce buildings are of the building grade. In the construction grade, the amount of putty powder is very large, about 90% is use or making putty powder, and the rest is use as cement mortar and glue.
3. What are the dissolution methods of hydroxypropyl methylcellulose HPMC?
Answer: Hot water dissolution method: Since HPMC is not dissolve in hot water, the initial HPMC can be uniformly disperse in hot water and then quickly dissolve during cooling. Two typical methods are describe as follows:
1) Adding 1/3 or 2/3 of the required amount of water to the vessel and heating to 70 ° C, dispersing HPMC according to 1) to prepare a hot water slurry; then adding the remaining amount of cold water to the hot water In the slurry, the mixture was cool after stirring.
Powder mixing method: Mix the HPMC powder with a large amount of other powdery substances, mix well with a blender, and then add water to dissolve. At this time, HPMC can be dissolve without agglomeration, because each tiny small corner has only a little HPMC. The powder will dissolve immediately upon contact with water. – This method is use by putty powder and mortar manufacturers. [Hydroxypropyl methylcellulose (HPMC) is use as a thickener and water retention agent in putty mortar.
2) Put the require amount of hot water in the container and heat it to about 70 °C. Hydroxypropyl methylcellulose was gradually add with slow stirring, and the HPMC float on the surface of the water, and then a slurry was gradually forme, and the slurry was cool with stirring.
4. How to judge the quality of hydroxypropyl methylcellulose (HPMC) simply and intuitively?
Answer: (1) Proportion: The bigger the proportion, the heavier the better. More important than it is because
(2) Whiteness: Although whiteness does not determine whether HPMC is easy to use, and if it is added to the brightener during the production process, it will affect its quality. However, good products are mostly white.
(3) Fineness: The fineness of HPMC generally has 80 mesh and 100 mesh, and 120 mesh is less. Most of HPMC produced in Hebei is 80 mesh. The finer the fineness, the better. Generally speaking, the better.
(4) Transmittance: Put hydroxypropyl methylcellulose (HPMC) in water to form a transparent colloid, and look at its transparency. The better the transmittance, the less insoluble matter. . The vertical reactor has a good permeability, and the horizontal reactor is worse, but it does not mean that the quality of the vertical reactor is better than that of the reactor. The quality of the product is determined by many factors. The content of hydroxypropyl group is high, and the content of hydroxypropyl group is high, so the water retention is better.
5. What are the main technical indicators of hydroxypropyl methylcellulose (HPMC)?
A: Hydroxypropyl content and viscosity, most users care about these two indicators. If the hydroxypropyl content is high, the water retention is generally better. Viscosity, water retention, relative (rather than
6. What is the viscosity of hydroxypropyl methylcellulose (HPMC)?
A: The putty powder is generally 100,000. The mortar is required to be higher, and it is necessary to use 150,000. 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, the viscosity is lower (70,000-80,000), it is also possible. Of course, the viscosity is larger, the relative water retention is better. When the viscosity exceeds 100,000, the effect of viscosity on water retention is Not too big. Absolutely), and the viscosity is higher, it is better to use in cement mortar.
7. What are the main raw materials for hydroxypropyl methylcellulose (HPMC)?
A: The main raw materials of hydroxypropyl methylcellulose (HPMC): refined cotton, methyl chloride, propylene oxide, other raw materials, such as caustic soda, acid, toluene, isopropanol.
8. What is the main role of HPMC in putty powder? Is there a chemical?
A: HPMC plays the role of thickening, water retention and construction in the putty powder. Thickening: Cellulose can be thickened to suspend, keep the solution uniform and uniform, and resistant to sagging.
Water retention: The putty powder is dried slowly, and the auxiliary ash calcium reacts 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 reactions and only plays a supporting role. Putty powder with water, on the wall, is a chemical reaction. Because of the formation of new substances, the putty powder on the wall is removed from the wall, ground into powder, and reused, it will not work, because a new substance has been formed (calcium carbonate). ).
The main components of ash calcium powder are: Ca(OH)2, a mixture of 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 formed, and HPMC only retains water, assists the better reaction of ash calcium, and does not participate in any reaction itself.
9.HPMC is a non-ionic cellulose ether, so what is non-ion?
A: Generally speaking, non-ion is a substance that is not in the water and does not ionize. Ionization refers to the process by which an electrolyte is dissociate into a freely moving charge ion in a specific solvent such as water or alcohol. For example, the salt that is eaten every day, sodium chloride (NaCl), is ionize to produce free-moving sodium ions (Na+) with positive charge and chloride (Cl) negatively charge. That is to say, HPMC is placed in water and does not dissociate into charge ions, but exists in the form of molecules.
10. Does the powder of putty powder have any relationship with HPMC?
A: The powder of putty powder is mainly related to the quality of gray calcium, and has little to do with HPMC. The low calcium content of gray calcium and the inappropriate ratio of CaO and Ca(OH)2 in gray calcium can cause powder loss. If it is related to HPMC, then if the water retention of HPMC is poor, it will also cause powder loss.
11. What is the gel temperature of hydroxypropyl methylcellulose?
A: The gel temperature of HPMC is related to its methoxy content. The lower the methoxy content, the higher the gel temperature.
12. How to choose the right hydroxypropyl methylcellulose (HPMC) for different purposes?
Answer: The application of putty powder: the requirement is lower, the viscosity is 100,000, it is ok, the important thing is to keep the water better. Application of mortar: high requirements, high viscosity, 150,000 is better. Glue application: Need instant type product, high viscosity.
13. What is the difference between the cold water instant type and the hot soluble type of hydroxypropyl methylcellulose in the production process?
A: HPMC’s cold water instant type is treat with glyoxal surface, and it is quickly disperse in cold water, but it is not really dissolve. When the viscosity is up, it is dissolve. The hot soluble form is not surface treat with glyoxal. When the amount of glyoxal is large, the dispersion is fast, but the viscosity is slow, and the amount is small.
14. What is the smell of hydroxypropyl methylcellulose (HPMC)?
Answer: 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 taste.
15. What is the alias of hydroxypropyl methylcellulose?
A: Hydroxypropyl methylcellulose, English: Hydroxypropyl Methyl Cellulose Abbreviation: HPMC or MHPC Alias: Hypromellose; Cellulose hydroxypropyl methyl ether; Hypromellose, Cellulose, 2-hydroxypropyl methyl Cellulose ether. Cellulose hydroxypropyl Methyl ether Hyprolose.
16. What is the relationship between viscosity and temperature of HPMC? What should be paid attention to in practical application?
A: The viscosity of HPMC is inversely proportional to temperature, that is, the viscosity increases with decreasing temperature. The viscosity of a product we usually refer to is the result of a 2% aqueous solution at a temperature of 20 degrees Celsius.
In practical applications, in areas with large temperature differences between summer and winter, it should be noted that it is recommend to use a relatively low viscosity during the winter, which is more conducive to construction. Otherwise, when the temperature is low, the viscosity of cellulose will increase, and when it is scrape, the hand feel will be heavy. Medium viscosity: 75000-100000 Mainly used for putty. Reason: Water retention is good. High viscosity: 150000-200000 Mainly used for polystyrene granule insulation mortar rubber powder and vitrify microbead insulation mortar. Reason: The viscosity is high, the mortar is not easy to fall off, sag, and the construction is improve.
17. The application of HPMC in putty powder, what is the cause of foam in putty powder?
A: HPMC plays the role of thickening, water retention and construction in the putty powder. Do not participate in any reaction. The reason for the bubble: 1, the water is too much. 2, the bottom layer is not dry, just scrape a layer on the top, it is also easy to foam.
If you have any questions, you can send them to my email : tanyatao@qinahaochem.com
whatsapp: 17718245679