Application principle of hydroxypropyl methylcellulose in bonding mortar plastering mortar

Shandong chuangyao Biotechnology Co., Ltd. has an annual output of 8000 tons of hydroxypropyl methyl cellulose. The company has imported the top international production equipment, has the most advanced cellulose ether and latex powder R & D center, and adopts international scientific management methods. After passing the ISO9002 quality system certification, the company passed the ISO14001 environmental management system certification and ohsm in China in 2009 and 2010 respectively S (occupational safety and health certification).

The industrial grade hydroxypropyl methyl cellulose produced by the company has the advantages of less ash, high transmittance, high viscosity, and good dispersibility in cold water. Application of HPMC in bonding mortar plastering mortar recommended brand: cy-150000; cy-200000 physical and chemical indicators: white powder solid hydroxypropyl (%) 7.0-12.0 methoxy (%) 26.0-32.0 drying loss (%) ≤ 3.0 ash (%) ≤ 2.0 transmittance (%) ≥ 90.0 bulk density (g / L) 400-450 pH value 5.0-8.0 mesh 100 mesh pass rate: 98%

Hydroxypropyl methyl cellulose (HPMC) gives wet mortar excellent viscosity, which can significantly increase the bonding ability between wet mortar and base course, improve the anti sag performance of mortar, improve the water retention performance of mortar, and enhance the strength of mortar. It is widely used in plastering mortar, external insulation system of external wall and bonding mortar of face brick. The thickening effect of HPMC can also increase the homogeneity and anti dispersion ability of fresh cement-based materials, prevent the stratification, segregation and bleeding of mortar and concrete, and can be used in fiber concrete, underwater concrete and self compacting concrete. The increase of viscosity of cement-based materials by hydroxypropylmethylcellulose results from the viscosity of hydroxypropyl methylcellulose solution. Viscosity is usually used to evaluate the viscosity of cellulose ether solution. The viscosity of hydroxypropyl methyl cellulose generally refers to the viscosity value measured by the specified measuring instrument (such as rotary viscometer) under the specified temperature (such as 20 ℃) and shear rate (or rotation rate, such as 20 RPM) of hydroxypropyl methyl cellulose solution with a certain concentration (such as 2%).

Viscosity is an important parameter to evaluate the performance of HPMC. The higher the viscosity of HPMC solution is, the better the viscosity of cement-based material is, the better the adhesion performance is to the base material, and the stronger the anti sag and anti dispersion ability are. However, if the viscosity is too high, it will affect the fluidity and operability of the cement-based material (such as sticking the plaster knife during the construction of plastering mortar). Therefore, the viscosity of HPMC used in dry mixed mortar is usually 100000-200000 MPa. S, while the viscosity of HPMC is lower for self leveling mortar and self compacting concrete, which requires higher fluidity, generally 300-800mpa. S. In addition, the thickening effect of HPMC will increase the water demand of cement-based materials, thus increasing the output of mortar. The viscosity of HPMC solution depends on the following factors: molecular weight (or degree of polymerization) and concentration of HPMC, solution temperature, shear rate and test method. The higher the degree of polymerization and molecular weight of HPMC, the higher the viscosity of its aqueous solution; the higher the content (or concentration) of HPMC is, the higher the viscosity of aqueous solution is. However, attention should be paid to the appropriate amount of HPMC in use, so as not to affect the working performance of mortar and concrete due to its high content. Like most liquids, the viscosity of cellulose solution will change with the increase of the content The higher the concentration of cellulose, the greater the effect of temperature; cellulose solution is usually pseudoplastic, with shear thinning property, the higher the shear rate, the smaller the viscosity.

Therefore, the cohesion of mortar will be reduced due to external force, which is conducive to the construction of mortar scraping, so that the mortar can have good workability and cohesiveness at the same time. However, when the concentration of cellulose solution is very low and the viscosity is very small, the solution will show the characteristics of Newtonian fluid, and the higher the concentration, the more obvious the pseudoplasticity.

Hydroxypropyl methyl cellulose (HPMC) is a kind of non-ionic cellulose ether which is made of natural polymer material (cotton) cellulose through a series of chemical processing. It is a kind of odorless, tasteless, non-toxic white powder, which is dissolved into a clear or slightly turbid colloidal solution in cold water. For more information about the product introduction of HPMC and the application of HPMC in mortar, please pay attention to the news on the company's website.