HPMC hydroxypropyl methylcellulose 20 questions (1)

Industrial grade hydroxypropyl methylcellulose for mortar (referred to herein as pure cellulose, excluding modified products) is distinguished by viscosity. Generally used are the following grades (unit is viscosity)

Low viscosity: 400 is mainly use for self-leveling mortar, but it is generally import. Reason: low viscosity, although the water retention is poor, but the leveling is good, the mortar density is high.

Medium and low viscosity: 20000-40000 is mainly use for tile adhesive, caulking agent, crack-resistant mortar, thermal insulation mortar, etc. Reason: good construction, less water, high mortar density.

1. 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 for making putty powder, and the rest is use as cement mortar and glue.

2, hydroxypropyl methylcellulose (HPMC) is divided into several, what is the difference in its use?

A: HPMC can be divided into instant-soluble and hot-dissolved, fast-dissolving products, which quickly disperse in cold water and disappear into water. At this point the liquid has no viscosity because the HPMC is only dispersed in the water and there is no real dissolution. About 2 minutes, the viscosity of the liquid gradually increased to form a transparent viscous colloid.

The hot-melt type product, in the case of cold water, can be quickly dispersed in hot water. It disappears into hot water, and when the temperature drops to a certain temperature, the viscosity gradually appears until a transparent viscous colloid is formed. Hot melt type can only be use in putty powder and mortar. In liquid glues and coatings, clumping can occur and cannot be used.

Instant type, a wide range of applications. It can be use in putty powder and mortar, as well as in liquid glue and paint. There are no taboos.

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. It then dissolves rapidly upon cooling. Two typical methods are describe below:

1) Place the require amount of hot water in the container and heat to about 70 °C. Hydroxypropyl methylcellulose was gradually add with slow stirring, and the HPMC floated on the surface of the water, and then a slurry was gradually form, and the slurry was cool with stirring.

2) Adding 1/3 or 2/3 of the required amount of water to the vessel and heating to 70 ° C, dispersing the HPMC according to the method of 1) to prepare a hot water slurry. The remaining amount of cold water is then add to the hot water slurry, and the mixture is cooled after stirring.

Powder mixing method: The HPMC powder is mix with a large amount of other powdery substances and thoroughly mix with a mixer. After adding water to dissolve, then HPMC can be dissolved without clumping. Because every little small corner, only a little HPMC powder will dissolve immediately when it meets water. This method is use by putty powder and mortar manufacturers.

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 it is add to the brightener during the production process, it will affect its quality. However, good products are mostly white.

(2) 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.

(3) Transmittance: Hydroxypropyl methylcellulose (HPMC) was place in water to form a transparent colloid. Look at its transparency, the better the transmittance, the less insoluble matter. The vertical reactor has a generally good permeability, and the horizontal reactor is worse. However, it cannot be said that the quality of the vertical kettle production is better than that of the horizontal kettle. The quality of the product is determine by many factors.

(4) Specific gravity: The larger the specific gravity, the heavier the weight. The ratio is large, generally because the content of hydroxypropyl group is high, and the content of hydroxypropyl group is high, the water retention is better.

5. What is the amount of hydroxypropyl methylcellulose (HPMC) in the putty powder?

A: The amount of HPMC used in practical applications varies depending on the climate, temperature, local ash calcium quality, formula of putty powder and “quality required by customers”.
In general terms, between 4 kg and 5 kg.

6. What is the viscosity of hydroxypropyl methylcellulose (HPMC)?

A: The putty powder is generally 100,000. The mortar is require 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.

7. 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 absolute), and high viscosity, better 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, such as caustic soda, acid, toluene, isopropanol.

9. 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 thicken 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 remove from the wall, ground into powder, and reuse, it will not work, because a new substance (calcium carbonate) has be form.

10, 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 dissociated 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 ionized to produce free-moving sodium ions (Na+) with positive charge and chloride (Cl) negatively charged. That is to say, HPMC is placed in water and does not dissociate into charged ions, but exists in the form of molecules.