Hydroxypropyl Methyl Cellulose (HPMC) is a high-performance non-ionic, water-soluble cellulose mixed ether. This odorless and tasteless white powder possesses excellent properties such as dispersion, emulsification, thickening, adhesion, water retention, and gel retention.
Water Retention and Thickening Effect: By forming a protective film in the mortar, HPMC contributes to complete hydration and prevents moisture loss, creating a strong bonding environment.
Dispersion and Emulsification: HPMC ensures uniform dispersion of particles and stable emulsion in mortar formulations.
Hydroxypropyl Methyl Cellulose comes in a variety of types and specifications. This reference guide is to help you choose the most suitable HPMC to improve your product in one of two ways.
1. Choosing HPMC Based on Its 3 Major Parameters
Viscosity
The viscosity of HPMC shapes properties such as water-retaining ability, thickening effect, and retarding performance. Thus, it is a crucial indicator for evaluating and selecting HPMC.
Before discussing the viscosity of HPMC, it is important to note that even for the same solution, results can vary depending on testing methods. There are some common methods to measure HPMC viscosity including Brookfield, Hakke, and Hoppler. The instruments, solution concentrations, and testing environments involved in these methods are different. Therefore, when assessing the viscosity of an HPMC polymer, ensure that details such as rotor type, temperature, and solution concentration are taken into account.
Take K2000, the TDS points that its viscosity of 65,000-80,000 mPas is obtained using Brookfield-RV under a 2% solution at 20℃.
Stability
HPMC is susceptible to degradation by cellulase, an enzyme produced by fungi, bacteria, and protozoans that catalyze cellulolysis. When cellulase attacks HPMC, it primarily targets the unetherified glucose units in the HPMC structure. As a linear polymer, HPMC faces a sharp decline in viscosity once a glucose unit is damaged. However, such enzymes find it difficult to degrade the molecular chain if glucose units are etherified. Therefore, the higher the degree of etherification substitution (DS value) of HPMC, the more stable it is.
Ash Content
The content of active ingredients in HPMC is directly proportional to its cost-effectiveness, which means better performance at the same dosage. The active ingredient in HPMC is etherified cellulose, an organic substance. Its content can be measured by the ash content from calcined HPMC. Generally, a higher ash value indicates a lower content of active ingredients. In the TDS of FUNAHAI HPMC, you could see the ash content is no more than 5%, implying the high purity of our products.
2. Selecting HPMC According to Mortar Types
repairing walls with putty and spatula
Cement-Based Plaster Mortar
The plastering mortar demands excellent uniformity for easy and even application, alongside good sag resistance, pumpability, and workability with high fluidity. Therefore, it is advisable to select an HPMC that possesses lower viscosity yet disperses swiftly and develops consistency rapidly( with finer particles) in the cement mortar mixture.
Male worker professional mounts ceramic tile in bathroom photo with close spatula with glue
Tile Adhesive
Tile adhesive should be endowed with a longer opening time, excellent anti-sag properties, and a strong bond between the substrate and tiles. To meet these standards, HPMC must have a high water retention rate and effective thickening properties, which in turn requires high viscosity, appropriate dosage, particle size, and degree of etherification. For example, K0200 HPMC is preferable.
What is ideal for anti-sag tile adhesives is HPMC with exceptional thickening properties. You may consider highly modified HPMC, like K75HT HPMC.
leveling the floor with a plaster screed
Self-Leveling Mortar
Self-leveling compounds are expected to spread out readily and level themselves on the ground, that is, good fluidity and pumpability, leading to a high water-to-material ratio. Taking these into account, the additive needs to be able to preserve water on the surface and prevent sedimentation. HPMC with relatively low viscosity like K04 would be nice.
Masonry of a large red brick
Masonry Mortar
Generally applied thickly, masonry mortar requires high workability and water retention while ensuring a strong bond with the masonry. Consequently, HPMC with low viscosity and certain moisture control ability stands out as an ideal choice.
Renovation of the facade of an old building with External thermal insulation cladding
External Insulation Finish System (EIFS)
Thermal insulation mortar is primarily applied manually, so the selected HPMC should impart good workability, excellent consistency, and outstanding water-retaining ability. This means HPMC should possess high viscosity and air-entraining properties. In light of these characteristics, you may consider using HPMC that offers high water retention, high viscosity, and good air-entraining performance, like K2000.
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