Views: 41 Author: Site Editor Publish Time: 2025-07-10 Origin: Site
Hot water dissolution: Heat water to around 70°C, gradually add HPMC while stirring. Initially, HPMC floats on the surface, but as the mixture cools, it gradually forms a slurry and dissolves. For larger volumes, disperse HPMC in a portion of hot water first, then add cold water and stir to cool.
Powder mixing: Premix HPMC powder thoroughly with other large-volume powdered ingredients before adding water. This prevents clumping, as each tiny particle contains only a small amount of HPMC, enabling rapid dissolution. This method is widely used by putty powder and mortar manufacturers, where HPMC acts as a key thickener and water-retaining agent.
4. How can HPMC quality be judged intuitively?
— Answer: Key visual indicators include whiteness, fineness, light transmittance, and specific gravity. Additionally, practical performance factors like water retention and viscosity matter. For example, in putty powder, 100,000 viscosity is generally sufficient, while mortars may require higher viscosity. However, viscosity is not the sole indicator—water retention is critical: even lower viscosity HPMC can perform well if water retention is strong. Beyond 100,000 viscosity, the impact of viscosity on water retention becomes less significant.5. What are the key technical indicators of HPMC?
— Answer: The primary indicators are hydroxypropyl content and viscosity. Higher hydroxypropyl content typically improves water retention; higher viscosity also enhances water retention, especially in cement mortars.
— Answer: Main raw materials include refined cotton, methyl chloride, and propylene oxide. Auxiliary materials may include caustic soda, acid, toluene, and isopropyl alcohol.
— Answer: HPMC serves three key functions: thickening (increasing viscosity to prevent sagging and ensure uniform suspension), water retention (prolonging drying time to aid the lime-water reaction), and improving workability (adding lubricity for easier application). Notably, HPMC does not participate in chemical reactions during putty preparation or application—it acts solely as a functional aid.
— Answer: No. HPMC is a nonionic cellulose ether, existing in molecular form (not ionized) in water. This unique property enables its effectiveness in diverse applications.
— Answer: Gel temperature is related to molecular weight: higher molecular weight generally increases the gel temperature.
— Answer: It may be, but not always. Poor water retention in HPMC can affect putty drying time, potentially causing bubbles. However, other factors are more likely primary causes, such as excessive water addition, applying a new layer over an undried base, or low-quality lime.
— Answer: Yes, when produced responsibly. Raw materials like refined cotton, methyl chloride, and propylene oxide are strictly controlled during production to ensure environmental safety. HPMC itself is biocompatible and biodegradable, qualifying it as an eco-friendly additive.
— Answer: Interior wall putty mainly consists of heavy calcium carbonate and lime calcium, supplemented by additives like starch ether. Exterior wall putty is based on cement, heavy calcium carbonate, and quartz sand, with added latex powder and cellulose ether to enhance durability and performance.
MC: Produced by alkalizing refined cotton and etherifying with methyl chloride. Its water retention depends on dosage, viscosity, particle size, and dissolution rate. It has moderate adhesion but poor high-temperature water retention (declining significantly at high temps, affecting mortar workability).
HPMC: A nonionic mixed ether, produced by alkalizing refined cotton and etherifying with propylene oxide and methyl chloride. It dissolves easily in cold water (not hot water) and has a higher gel temperature than MC. Its solutions are stable at room temperature, resistant to acids/bases (performing stably at pH 2–12), and unaffected by caustic soda or limewater (which may even accelerate dissolution and slightly boost viscosity). HPMC offers better water retention (exceeding MC at the same dosage), stronger mortar adhesion, and superior enzyme resistance. It also mixes well with other water-soluble polymers (e.g., polyvinyl alcohol, starch ethers) to form higher-viscosity homogeneous solutions.
— Answer: HPMC viscosity is inversely proportional to temperature, so adjust for seasonal temperature differences. In winter, opt for lower viscosity products: cold temperatures increase viscosity, which can make application feel "heavy." In warmer seasons, higher viscosity may be suitable to maintain performance.
