Hydroxypropyl methyl cellulose HPMC common problems

1. What is the main use of hydroxypropyl methyl cellulose?

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 industrial grade, food grade and medical grade according to the use.

2. Hydroxypropyl methyl cellulose is divided into several kinds, what is the difference between them?

HPMC can be divided into instant (brand suffix “S”) and hot soluble, instant products, in cold water quickly dispersed, disappeared in the water, at this time the liquid has no viscosity, because HPMC is just dispersed in the water, no real dissolution. About 2 minutes, the viscosity of the liquid gradually increases, forming a clear and sticky gel. Heat soluble products, clumped in cold water, can quickly disperse in hot water, disappear in hot water, such as temperature drops to a certain temperature (according to the gel temperature of the product), viscosity slowly appear, until the formation of transparent viscous colloid.

3. How to determine the quality of hydroxypropyl methyl cellulose simply and intuitively?
1) whiteness, although whiteness can not determine whether HPMC is good, and if it is added in the production process whitener, will affect its quality, but, good products mostly whiteness is good.
2) fineness: HPMC fineness is generally 80 mesh and 100 mesh, 120 purpose less, the finer the better.
3) light transmittance: HPMC in the water, forming a transparent colloid, see its light transmittance, the larger the penetrability of the good, explain insolubles less inside, vertical reaction kettle by degrees generally good, will send some of horizontal reaction kettle, but cannot explain the vertical kettle production quality is better than lie kettle production, there are many factors that determine product quality.
4) proportion: the larger the proportion, the heavier the better, than the major, generally because of the high content of hydroxypropyl inside, hydroxypropyl content is high, the water retention is better.

4. What are the dissolution methods of hydroxypropyl methyl cellulose?
1) All models can be added into the material by dry mixing method;
2) Need to be directly added to the normal temperature water solution, it is better to use cold water dispersion, after adding generally in 10-90 minutes to thicken (stir stir stir)
3) Ordinary models can be dissolved after mixing and dispersing with hot water and adding cold water after stirring and cooling;
4) When dissolving, if the phenomenon of agglomerating occurs, it is because the stirring is not sufficient or the ordinary model is directly added into the cold water. At this time, it should be stirred quickly.
5) If bubbles occur during dissolution, they can be removed by standing for 2-12 hours (the specific time depends on the consistency of the solution) or by vacuumizing and pressurizing, or by adding an appropriate amount of defoaming agent.

5 hydroxypropyl methyl cellulose in the volume of putty powder?
HPMC in the actual application of the amount, by the climate environment, temperature, local gray calcium quality, putty powder formula and customer requirements of the different quality, and there are differences around, generally between 4-5 kilograms.

6. What is the appropriate viscosity of hydroxypropyl methyl cellulose?
Putty powder is generally 100000 can, mortar requirements are higher, to 150000 just good, and HPMC is more important role is water retention, followed by thickening. In putty powder, as long as the water retention is good, the viscosity is low (7-8), it is also possible, of course, the viscosity is bigger, the relative water retention is better, when the viscosity is more than 100,000, the viscosity of water retention is not much.

7. What are the main raw materials of hydroxypropyl methyl cellulose?
HPMC main raw materials: refined cotton, chloromethane, propylene oxide, other raw materials, tablet alkali, acid toluene.

8. Hydroxypropyl methyl cellulose in the application of putty powder, the main role, whether chemical?
In putty powder, thickening, water retention and construction of three functions. Thickening, cellulose can be thickened to suspension, so that the solution remains uniform up and down the role of anti-flow hanging. Water retention: make putty powder dry slowly, auxiliary gray calcium in the action of water reaction. Construction: cellulose lubrication, can make putty powder has good construction. HPMC does not participate in any chemical reactions, but only plays a supporting role.

9 .hydroxypropyl methyl cellulose is non-ionic cellulose ether, so what is non-ionic?
In layman’s terms, inert substances do not participate in chemical reactions.
CMC(carboxymethyl cellulose) is cationic cellulose, so encounter gray calcium will become bean curd residue.

10. What are the main technical indicators of hydroxypropyl methyl cellulose?
Hydroxypropyl content
Methyl content
viscosity
ash
Dry weight loss

11. What is related to the gel temperature of hydroxypropyl methyl cellulose?
The gel temperature of HPMC is related to the methoxyl content, the lower the methoxyl content, the higher the gel temperature.

12 putty powder drop powder and hydroxypropyl methyl cellulose relationship?
If HPMC is poor water retention, will cause the powder.

13 hydroxypropyl methyl cellulose in the application of putty powder, putty powder bubble what reason?
HPMC in the putty powder, the thickening, water retention and construction of three roles, the cause of the bubble:
1. )Too much water is added.
2. )The bottom layer is not dry, and then scrape a layer on it, which is also easy to blister.

14. What is the difference between the cold-water quick-soluble and heat-soluble hydroxypropyl methyl cellulose in the production process?
HPMC cold water instant solution type is after glyoxal surface treatment, put in cold water quickly dispersed, but not really dissolved, viscosity up, is dissolved. The thermosoluble type has not been surface treated with glyoxal. The amount of glyoxal is large, the dispersion is fast, but the viscosity is slow, the amount is small, on the contrary.

15. What is it about hydroxypropyl methyl cellulose smells?
HPMC produced by solvent method is made of toluene and isopropyl alcohol. If the washing is not very good, there will be some residual taste. (Neutralization recovery is the key process for odor)

16. How to choose appropriate hydroxypropyl methyl cellulose for different uses?
Putty powder: high water retention requirements, good construction compatibility (recommended grade: 75AX100000)
Ordinary cement-based mortar: high water retention, high temperature resistance, instant viscosity (recommended grade: 75AX150000)
Application of building glue: instant products, high viscosity. (Recommended brand Number: 75AX200000S)
Gypsum mortar: high water retention, medium and low viscosity, instant viscosity (recommended grade: 75AX75000)

17. What is the nickname for hydroxypropyl methyl cellulose?
HPMC or MHPC alias hydroxypropyl methyl cellulose, cellulose hydroxypropyl methyl ether.

18. What is the difference between hydroxypropyl methyl cellulose and MC?
MC is methyl cellulose, is refined cotton after alkali treatment, methane chloride as etherifying agent, through a series of reactions and made of cellulose ether, general degree of substitution is 1.6-2.0, different degree of substitution solubility is also different, belongs to non-ionic cellulose ether.
(1) The water retention of methyl cellulose depends on its addition amount, viscosity, particle fineness and dissolution rate. Generally, the addition amount is large, the fineness is small, the viscosity is large, the water retention rate is high, the addition amount has a great influence on the water retention rate, the viscosity and water retention rate is not lower than the relationship, the dissolution rate mainly depends on the surface modification degree and particle fineness of cellulose particles. Methyl cellulose and hydroxypropyl methyl cellulose in the above several cellulose ethers have higher water retention rate.
(2) Methyl cellulose can be dissolved in cold water, hot water will be difficult to dissolve, its aqueous solution in the pH =3-12 range is very stable, and starch, etc., and many surfactants have good compatibility, when the temperature reaches the gelation temperature, there will be gelation phenomenon.
(3) Temperature changes will seriously affect the water retention rate of methyl cellulose, generally, the higher the temperature, the worse the water retention. If the temperature of mortar exceeds 40 degrees, the water retention of methyl cellulose will be significantly worse, which seriously affects the constructability of mortar.
(4) Methyl cellulose has obvious influence on the constructability and adhesion of mortar. The adhesion here refers to the adhesive force felt between the tool and the wall substrate by the worker, that is, the shear resistance of the mortar. Adhesion is large, the shear resistance of mortar is large, the strength required by workers in the process of use is also large, and the construction of mortar is poor.