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HPMC and MHEC serve as thickeners, dispersants, water retention agents, and air-entraining agents, primarily in cement and gypsum-based dry mix mortars. They enhance bond strength, workability, and water retention, reducing water loss on concrete surfaces to prevent cracks and improve surface coverage. These properties make them widely used in wall plaster and tile adhesive products.
In paints, HPMC and MHEC act as protective colloids, aiding in the polymerization of vinyl acetate emulsions and improving the stability of the polymerization system across a wide pH range. They facilitate the even dispersion and stabilization of pigments, fillers, and other additives in the manufacturing of finished products while also providing a thickening effect.
Thermal stability of HPMC and MHEC is affected by their gel temperature.
In general, the gel temperature of HPMC is around 60℃-75℃ depending on its group content and different production technique. Due to the characteristics of MHEC group, it has a higher gel temperature, usually > 80℃.
In practical construction, especially in hot summer environments, MHEC demonstrates superior water retention compared to HPMC when used at the same viscosity and dosage. This is particularly important in Southeast Asian countries and India, where mortar is often applied in high temperatures. Cellulose ethers with low gel temperatures can lose their thickening and water-retaining properties under such conditions, leading to faster mortar hardening and impacting the construction process.
Additionally, MHEC's structure contains more hydrophilic groups, enhancing its hydrophilicity. As a result, the water retention rate of MHEC in mortar is slightly higher than that of HPMC when both are used at the same dosage and viscosity.
HPMC is a non-ionic cellulose ether made from refined cotton after alkalization, using propylene oxide and methyl chloride as etherification agents, through a series of reactions; and MHEC is produced from refined cotton after alkalization treatment, using ethylene oxide and methyl chloride as etherification agents, after a series of reactions, because the storage and use risk factor of ethylene oxide is higher than that of propylene oxide, so The production technology and process requirements of MHEC are higher. There are fewer manufacturers and the price of MHEC is higher than that of HPMC.
MHEC has a higher gel temperature, typically ranging from 78-85 ℃, compared to HPMC, which generally reaches about 60-75 ℃. This makes MHEC more effective in high-temperature resistance, which is a key reason many customers in hot regions prefer it.
While MHEC usually offers slightly better water retention than HPMC, the difference is not significant. Customers often choose HPMC for its cost-effectiveness when high gel temperature isn't a critical requirement. Additionally, MHEC tends to provide greater viscosity stability, mildew resistance, and dispersibility compared to HPMC.
MHEC has a higher gel temperature, typically reaching around 78-85°C, compared to HPMC, which generally has a gel temperature of about 60-75°C. This makes MHEC more effective in high-temperature resistance, which is a key reason why many customers in hot regions prefer it.
While MHEC generally offers better water retention than HPMC, the difference is not significant. For customers who do not have stringent gel temperature requirements, HPMC is often the preferred choice due to its lower cost. Additionally, MHEC typically exhibits greater viscosity stability, mildew resistance, and dispersibility compared to HPMC.
