The industrial grade hydroxypropyl methylcellulose used for mortar (here refers to pure cellulose, excluding modified products) is distinguished by viscosity, and the following grades are commonly used (the unit is viscosity):
Low viscosity: 400
It is mainly used for self-leveling mortar; the viscosity is low, although the water retention is poor, but the leveling property is good, and the mortar density is high.
Medium and low viscosity: 20000-40000
Mainly used for tile adhesives, caulking agents, anti-cracking mortars, thermal insulation bonding mortars, etc.; good construction, less water, high mortar density.
Medium viscosity: 75000-100000
Mainly used for putty; good water retention.
High viscosity: 150000-200000
It is mainly used for polystyrene particle thermal insulation mortar rubber powder and vitrified microbead thermal insulation mortar; the viscosity is high, the mortar is not easy to fall off, and the construction is improved.
In practical applications, it should be noted that in areas with large temperature differences between summer and winter, it is recommended to use a relatively low viscosity in winter, which is more conducive to construction. Otherwise, when the temperature is low, the viscosity of the cellulose will increase, and the hand feel will be heavy when scraping.
Generally speaking, the higher the viscosity, the better the water retention. Considering the cost, many dry powder mortar factories replace medium and low viscosity cellulose (20000-40000) with medium-viscosity cellulose (75000-100000) to reduce the amount of addition. Mortar products should be selected from regular manufacturers and identified.
The relationship between viscosity and temperature of HPMC:
The viscosity of HPMC is inversely proportional to temperature, that is, the viscosity increases as the temperature decreases. The viscosity of a product we usually refer to refers to the test result of its 2% aqueous solution at a temperature of 20 degrees Celsius.
Post time: Mar-06-2023