2022/03/22 12:00
Hydroxypropyl Methyl Cellulose-HPMC, as additive widely used in the field of building materials, is mainly used for water retention, thickening and improving the workability of the finished product.
Water retention rate is one of the core indicators when you choose high-quality HPMC, so let's take a closer look at the factors t affecting the water retention rate of HPMC.
1. The dosage of the HPMC, and its water retention performance is directly proportional to the added amount. The amount of HPMC used in building materials on the market varies depending on the quality. Taking the high-quality HPMC produced by Mellutel® Cellulose Ether as an example, it is generally added in such as bonding, plastering, anti-cracking mortar, etc. The general addition amount is 2~2.5 KG /MT, the adding amount of putty etc. is between 2~4.5 KG/MT, the tile glue is between 3.5~4 KG/MT, and the amount of tile grout is 0.3 ~1 KG/MT according to different construction methods, gap width and slurry fineness , the self-leveling mortar is between 0.2~0.6 KG/MT, and the ETICS is between 4~7 KG/MT. Within this range, the more HPMC is added, the water retention performance would be better.
2.The impact of construction environment. Air humidity, temperature, wind pressure, wind speed and other factors will affect the volatilization rate of water in cement mortar and gypsum-based products. In different seasons and different regions, the water retention rate of the same product will vary, but in general, Temperature has a great influence on the water retention rate, so there is a view on the market: HPMC with higher gel temperature is a high-quality product with high water retention rate, and the high-quality HPMC produced by Mellutel® Cellulose Ether has a gel temperature far exceeding the Similar products.
3.The production process and viscosity of the cellulose ether -HPMC. The high-quality HPMC produced by Mellutel® Cellulose Ether has very good uniformity. Its methoxy and hydroxypropoxy groups are evenly distributed along the cellulose molecular chain, which can increase the association of the oxygen atoms on the hydroxyl and ether bonds with water. The ability of hydrogen bonding makes free water become bound water,thereby effectively controlling the evaporation of water and achieving high water retention.
When the viscosity of HPMC increases, the water retention rate also increases, the viscosity reaches a certain level, the water retention rate increases. It tends to be flat. Taking the high-quality HPMC produced by Mellutel® Cellulose Ether as an example, laboratory data show that within 100,000 cps (NDJ), the viscosity is positively correlated with the water retention rate.
A simple overview. The water retention function of HPMC is affected by all aspects. The choice cannot be based on a single indicator. Due to its advanced technology, the high-quality HPMC produced by Mellutel® Cellulose Ether can achieve better water retention performance in the case of low viscosity. In a word, it is the right choice for HPMC to choose Mellutel® Cellulose Ether.