Choosing the appropriate HPMC viscosity range needs to be determined according to the specific application scenario and needs. The following are detailed guidance suggestions:

1. Choose the viscosity range according to the application field

The viscosity range of HPMC usually ranges from ultra-low viscosity (such as 5 mPa·s) to high viscosity (such as 400,000 mPa·s). Different viscosities are suitable for different purposes:
• Construction industry:
o Putty powder: HPMC with a viscosity of about 100,000 (100,000 mPa·s) is usually selected, because lower viscosity can also meet the water retention requirements.
o Dry-mixed mortar: HPMC with a viscosity of 150,000 (150,000 mPa·s) and above is recommended to ensure better water retention and construction performance.
o Self-leveling mortar: HPMC with a viscosity of 400 (400 mPa·s) is usually used to improve rheological properties.
• Pharmaceutical industry:
o HPMC usually requires a specific viscosity range in the pharmacopoeia, for example, the viscosity range of a 2% aqueous solution at 25°C must meet the regulations (such as 25,000-50,000 mPa·s).
o Low viscosity HPMC (such as 5,000-10,000 mPa·s) is often used as an adhesive in tablet coating and wet granulation.
• Industrial and food industries:
o High viscosity HPMC (such as 200,000 and above) is suitable for occasions that require strong thickening and water retention, such as coatings, water treatment, etc.

2. Consider the rapid solubility and slow solubility of HPMC

HPMC is divided into rapid solubility (with “S” suffix, such as 100,000S) and slow solubility (without “S” suffix, such as 100,000).
Rapid solubility HPMC disperses faster in cold water and is suitable for scenarios where solutions are prepared quickly.
Slow solubility is suitable for occasions that require hot water dissolution.

3. Combine water retention and construction performance

The main functions of HPMC are water retention and thickening. High-viscosity HPMC (such as 150,000 and above) generally has better water retention and construction performance, and is suitable for scenes that require long-term water retention (such as mortar and putty).
Low-viscosity HPMC (such as below 100,000) is suitable for scenes that do not require high water retention.

4. Pay attention to the effect of temperature on viscosity

The viscosity of HPMC is inversely proportional to temperature, that is, the viscosity increases when the temperature decreases. When constructing in winter, it is recommended to choose HPMC with lower viscosity to avoid construction difficulties caused by excessive viscosity.

5. Refer to product specifications and technical indicators

When selecting HPMC, it is necessary to combine the technical indicators of the product. Such as hydroxypropyl content, methoxyl content, moisture content, etc., these parameters will affect the performance of HPMC. For example, HPMC with a high methoxyl content generally has better enzyme resistance and hydrolysis resistance.

Summary

• Putty powder: 100,000 viscosity (100,000 mPa·s)
• Mortar: 150,000 and above viscosity (150,000 mPa·s and above).
• Pharmaceutical: Select a specific viscosity range according to pharmacopoeia requirements.
• Industrial and food: Select high viscosity (such as 200,000 and above) according to thickening and water retention requirements.
By comprehensively considering the above factors, the appropriate HPMC viscosity range can be selected to meet specific needs.