What are the grades of HPMC?

Hydroxypropyl methylcellulose (HPMC) can be graded based on multiple technical dimensions, including viscosity, substituent content, solubility, and application areas, to meet the functional requirements of different industrial scenarios.

I. Viscosity Grade

HPMC viscosity is a key performance indicator, typically classified into low, medium, and high grades based on the viscosity value of an aqueous solution at a specific concentration. Low-viscosity grades are suitable for systems requiring high fluidity; medium-viscosity grades are commonly found in building mortars and general coatings, offering both thickening and water-retention properties; high-viscosity grades are mainly used in thick coatings or high-viscosity formulations requiring strong suspension and structural stability.

II. Substituent Type and Content

The performance of HPMC is significantly affected by the content and ratio of its substituents—methoxy and hydroxypropoxy groups. Higher methoxy content generally results in better water solubility and film-forming properties; increased hydroxypropoxy content helps improve its compatibility with organic solvents and adhesion. Different substituent types of HPMC are suitable for specific fields such as building materials, drug sustained release, food stabilization, and cosmetic formulations.

III. Solubility Characteristics

Based on their solubility behavior, HPMCs can be divided into fast-dissolving and sustained-release types. Fast-dissolving HPMCs are suitable for applications requiring rapid formation of a homogeneous liquid phase; sustained-release HPMCs are mostly used in controlled-release drugs or long-lasting moisturizing products, gradually dissolving and exerting their effects within the system.

IV. Application Grade Classification

Based on application areas, HPMCs include pharmaceutical grade, food grade, industrial grade, and cosmetic grade. Each grade differs in purity, impurity control, and physicochemical properties to meet the requirements of pharmacopoeias, food standards, or industry application specifications.

In summary, the selection of HPMC grade should be based on the specific performance requirements and process conditions of the application scenario. Appropriate selection is essential to fully utilize its functional characteristics.