What is the choice of HPMC viscosity when producing putty powder dry mortar?
November 26th 2024
Methyl cellulose MC and hydroxypropyl methyl cellulose (HPMC) have stable chemical properties. Mildew resistance and water retention are not affected by changes in pH.
Viscosity can be used between 50,000 and 200,000, but in production, higher viscosity is better. Viscosity is inversely proportional to bond strength. The higher the viscosity, the lower the strength.
Regarding the quality of cellulose, mainly the viscosity, it can be tested using a rotational viscometer; or it can be compared by a simple method.
For the comparison, take 1 gram of cellulose of the same viscosity. Add 100 grams of water, put it in a disposable cup and pour it out at the same time. Observe which one dissolves faster, has better clarity and thickens better. The better the transparency, the less impurities.
It is used for low-grade putty powder for interior walls, which has certain thickening and water retention effect and can increase leveling. However, it cannot be used for waterproof putty and external insulation dry mix.
This is because these cellulose will react with cement, grey calcium powder and gypsum powder, inorganic binders.
Many people think that these cellulose are alkaline, and generally cement and grey calcium powder are also alkaline. It is thought that they can be used in combination. However, CMC and CMS are not single elements.
The chloroacetic acid they use in the production process is acidic. The residue of the cellulose production process reacts with cement and gray calcium powder. So they cannot be combined. Many manufacturers have suffered great losses, which should be taken seriously.
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