Hydroxypropyl methylcellulose four questions
definition:
Hydroxypropyl methylcellulose, also known as hypromellose, cellulose hydroxypropyl methyl ether, is obtained by using high purity cotton cellulose as a raw material and special etherification under alkaline conditions.
effect:
Hydroxypropyl methylcellulose is use as a water retaining agent and retarder for cement mortar to make the mortar pumpable.
In the plaster, gypsum, putty powder or other building materials as a binder, improve the spreadability and extend the operation time.
Used as a paste tile, marble, plastic decoration, paste enhancer, can also reduce the amount of cement.
The water retention of HPMC enables the slurry to not crack too quickly after application, and enhances the strength after hardening.
classification:
Industrial grade hydroxypropyl methylcellulose for mortar (referred to as pure cellulose, excluding modified products) is distinguished by viscosity.
Generally used are the following brands (in terms of viscosity):
Low viscosity: 400 is mainly used for self-leveling mortar, but it is generally importe.
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, anti-cracking mortar, thermal insulation mortar and so on.
Reasons: good construction, less water, and high mortar density.
1. What is the main use of hydroxypropyl methylcellulose?
HPMC is widely use in building materials, coatings, synthetic resins, ceramics, pharmaceuticals, food, textiles, agriculture, cosmetics, tobacco and other industries.
HPMC can be divid into: building grade, food grade and pharmaceutical grade according to use.
At present, most of them are building grade. In the construction grade, the amount of putty powder is very large, about 90% is used for making putty powder, and the rest is use as cement mortar and glue.
2. What are the dissolution methods of hydroxypropyl methylcellulose?
1). All models can be add to the material by dry mixing method;
2). When it is necessary to directly add to the normal temperature aqueous solution, it is preferable to use a cold water dispersion type, and it is generally thicken after 10-90 minutes after the addition;
3). The ordinary model is first stirred with hot water and disperse, then add with cold water and stirred to dissolve.
4). If agglomeration occurs during dissolution, it is cause by insufficient stirring or direct addition of ordinary models to cold water. At this time, stir quickly.
5). If bubbles are generate during dissolution, it can be allow to stand for 2-12 hours (depending on the consistency of the solution) or vacuume, pressurized, etc., or an appropriate amount of defoamer can be add.
3. How to judge the quality of hydroxypropyl methylcellulose simply and intuitively
1) Whiteness, whiteness Although it is not possible to determine whether HPMC is easy to use, and if it is add to the whitening agent in the production process, it will affect its quality, but good products are mostly white.
2) Fineness: The fineness of HPMC generally has 80 mesh and 100 mesh, and 120 mesh is less. The finer the fineness, the better.
3) Transmittance: HPMC is place in water to form a transparent colloid, and its transparency is observe. The better the transmittance, the less insoluble matter, and the transparency of the vertical reactor is generally good.
The horizontal reactor is worse, but it does not mean that the quality of the vertical reactor is better than that of the kettle. The quality of the product is determine by many factors.
4) Specific gravity: The larger the specific gravity, the heavier the weight is, the more important it is. Because the hydroxypropyl content is high and the hydroxypropyl content is high, the water retention is better.
4. What is the amount of hydroxypropyl methylcellulose in putty powder?
The amount of HPMC used in practical applications depends on the climate, temperature, and local ash calcium quality. The formula of the putty powder and the quality required by the customer vary from place to place, and in general it is between 4-5 kg.