What is the appropriate viscosity of hydroxypropyl methylcellulose (HPMC)?

1. Building materials
In building materials, HPMC is mainly used in cement-based or gypsum-based products, such as putty, mortar, tile adhesive, coating, etc. The choice of viscosity will affect the construction performance and final product quality:

Putty powder: Generally choose 50,000-100,000 mPa·s, which can improve construction performance and enhance water retention.
Tile adhesive: HPMC with 75,000-100,000 mPa·s is commonly used to improve adhesion and anti-slip properties.
Self-leveling mortar: Usually choose a lower viscosity, such as 400-4,000 mPa·s, to reduce the viscosity of the mixture and improve fluidity.

2. Medicine and Food
HPMC is mainly used as thickener, emulsifier, capsule shell material, etc. in the field of medicine and food. Different uses require different viscosities:

Medicinal capsule shell: 3,000-5,600 mPa·s is often used to ensure the film-forming performance and disintegration time of the capsule.

Sustained-release tablets: 15,000-100,000 mPa·s is usually used as a skeleton material to control the drug release rate.

Food additives: Low viscosity HPMC (such as 100-5,000 mPa·s) is often used to thicken and stabilize food structure.

3. Coatings and inks
HPMC can be used as a thickener in water-based coatings and inks to improve coating stability and brushing performance:

Water-based coatings: 5,000-40,000 mPa·s is often selected to improve rheology and anti-sagging properties.
Ink: Low viscosity products (400-5,000 mPa·s) are more common to ensure good fluidity and uniform dispersion.

4. Daily chemical products
HPMC is mainly used for thickening and stabilizing emulsified systems in daily chemical products such as detergents and skin care products:

Shampoo and shower gel: 1,000-10,000 mPa·s are mostly used to ensure appropriate rheological properties.
Skin cream: The viscosity range is generally 10,000-75,000 mPa·s, which helps to improve the application feel and moisturizing effect.
Notes on viscosity selection
The viscosity of HPMC is affected by temperature and needs to be adjusted appropriately according to the use environment.
The higher the viscosity, the longer the dissolution time, so high viscosity HPMC usually needs to be dissolved in advance or properly pretreated.
In specific applications, it is recommended to conduct small-scale experiments to find the most suitable viscosity range.

The viscosity of HPMC should be determined according to the actual application. Generally speaking:
Low viscosity (400-5,000 mPa·s) is suitable for applications with high fluidity requirements, such as self-leveling mortar, ink, detergent, etc.
Medium viscosity (5,000-75,000 mPa·s) is suitable for coatings, skin care products, some building materials, etc.
High viscosity (75,000-100,000+ mPa·s) is suitable for applications such as tile adhesive, putty powder, and sustained-release drugs that require higher adhesion and film-forming properties.
When selecting the viscosity of HPMC, it is recommended to combine specific needs, formulation system and process conditions to ensure optimal performance.