When producing putty powder and dry mortar, choosing the right viscosity of hydroxypropyl methylcellulose (HPMC) is crucial to the performance of the product. As an important chemical additive, HPMC has the functions of thickening, water retention, and stabilization.

1. The role of HPMC in putty powder and dry mortar

Thickening: HPMC can effectively increase the consistency of putty powder and dry mortar to ensure good workability and adhesion during construction.
Water retention: HPMC has excellent water retention and can reduce the rapid loss of water, thereby extending the operability time of putty powder and dry mortar, which is beneficial to improve the strength and bonding properties of the final product.
Stability: HPMC can prevent stratification and segregation of dry mortar and putty powder during storage and maintain the uniformity of the mixture.
Workability: By improving rheological properties, HPMC can improve the workability of the product, making it smoother during application and spraying, and reducing shrinkage and cracks after construction.

2. Factors affecting the selection of HPMC viscosity

When selecting the viscosity of HPMC, the following key factors need to be considered:
Product type and application: Putty powder and dry mortar have different uses and require different viscosities. For example, wall putty powder requires higher viscosity for better suspension, while floor mortar may require lower viscosity for better fluidity.
Construction method: Different construction methods have different requirements for the viscosity of HPMC. Manual application generally requires higher viscosity, while mechanical spraying requires medium and low viscosity to ensure smooth construction.
Environmental conditions: Ambient temperature and humidity can affect the performance of HPMC. Under high temperature conditions, choosing a higher viscosity HPMC can better control water loss, while in a high humidity environment, a lower viscosity HPMC can improve construction.
Formulation system: Other ingredients included in the formula of putty powder and dry mortar will also affect the selection of HPMC. For example, the presence of other thickeners, fillers or additives may require the viscosity of HPMC to be adjusted to achieve a balance.

3. Selection criteria for HPMC viscosity
The viscosity of HPMC is generally expressed in mPa·s (milliPascal seconds). The following are common HPMC viscosity selection criteria:

Putty powder:
Wall putty powder: HPMC with 150,000-200,000 mPa·s is suitable for manual operation and higher suspension requirements.
Floor putty powder: HPMC with 50,000-100,000 mPa·s is more suitable to ensure fluidity and spreadability.

Dry mortar:
Masonry mortar: HPMC with 30,000-60,000 mPa·s is suitable for improving water retention and construction performance.
Plastering mortar: HPMC with 75,000-100,000 mPa·s can increase consistency and is suitable for manual application.
Tile adhesive: HPMC with 100,000-150,000 mPa·s is suitable for tile adhesives that require higher bonding strength.
Special purpose mortar: such as self-leveling mortar and repair mortar, low viscosity HPMC (20,000-40,000 mPa·s) is usually used to ensure good fluidity and self-leveling performance.

IV. Practical recommendations for HPMC viscosity selection

In the actual production process, the following recommendations should be followed when selecting HPMC viscosity:
Experimental verification: Before mass production, small-scale experiments are carried out to verify the effect of HPMC viscosity on product performance. Including key performance parameters such as construction, water retention, and hardening speed.
Supplier recommendations: Consult the technical support of the HPMC supplier for detailed information and recommendations about the product. They are usually able to provide HPMC samples with different viscosities for testing.
Adjustment and optimization: According to the actual use effect, the viscosity of HPMC is continuously adjusted to optimize product performance. During the application process, the selection of HPMC is adjusted in time considering the changes in formulation and environmental changes.

V. Testing and quality control of HPMC viscosity

After selecting HPMC with appropriate viscosity, quality control is also key:
Viscosity determination: Regularly test the viscosity of HPMC solution using a standard viscometer (such as Brookfield viscometer) to ensure that it meets the specification requirements.
Water retention test: Test the water retention of putty powder and dry mortar to ensure that the water retention effect of HPMC meets the expected standards.
Construction test: Test the workability of the product in actual construction to ensure that the thickening effect of HPMC does not affect the operability.

Selecting HPMC with the right viscosity is essential for the production of high-performance putty powder and dry mortar. Depending on the product use, construction method, environmental conditions and formulation system, HPMC with different viscosities needs to be selected to meet specific needs. Through experimental verification, supplier recommendations, adjustment optimization and quality control, it can be ensured that the final product has good workability, water retention and stability, thereby improving the market competitiveness of the product.