Hydroxypropyl Methylcellulose (HPMC) is a commonly used water-soluble cellulose derivative with a wide range of applications, including in the construction, pharmaceutical, food, cosmetics and other industries. It is synthesized by methylation and hydroxypropylation of cellulose, so it has very good solubility, viscosity adjustment and film-forming properties.
1. Grading by viscosity
The grades of Hydroxypropyl Methylcellulose are often classified according to the viscosity of its solution. Viscosity is one of the most important performance indicators of the material, and the common unit is mPa·s. The size of the viscosity is closely related to factors such as molecular weight and solubility.
Low viscosity grades (for example: E4M, E5, E10, etc.): These varieties of HPMC usually have low viscosity and are suitable for use in applications that require lower fluidity. For example, in some lightly thickened formulations, low-viscosity HPMC is often used to adjust the rheology of the solution.
Medium viscosity grade (e.g. K4M, K15M, K100M, etc.): This is the most common type of viscosity grade, suitable for use in construction, coatings, and certain pharmaceutical formulations. Medium viscosity HPMC can provide better thickening effects while maintaining appropriate solubility and stability.
High viscosity grade (e.g. HPMC K100M, HPMC K200M, etc.): High viscosity HPMC is often used in formulations that require higher viscosity, such as thick coatings, heavy building materials, or certain high-viscosity pharmaceutical preparations. Its high viscosity can provide strong suspension and stability.
The specific value of viscosity (e.g. 4,000 mPa·s, 10,000 mPa·s, etc.) is usually expressed by the measurement value of a solution of a specific concentration (e.g. 2%).
2. Classification by methylation degree
Methylation degree (Methoxyl Content) refers to the content of methyl (-OCH3) groups in hydroxypropyl methylcellulose. This parameter has an important influence on the solubility, rheological properties, and compatibility of HPMC with other substances.
High methylation degree (≥28%): This type of HPMC has a higher degree of methylation and usually has better water solubility and stability. They are often used in water-based coatings and building materials because they can provide better thickening and film-forming effects.
Medium methylation degree (22%-28%): These varieties of HPMC usually have better balanced properties and are suitable for a variety of fields, such as medicine, food, cosmetics, etc., and can meet most application requirements.
Low methylation degree (≤22%): HPMC with low methylation has poor solubility, but in certain specific applications, such as drug controlled release agents, it may be selected for use due to its characteristics.
3. Classification by hydroxypropyl content
Hydroxypropyl content is another important classification standard for HPMC. The degree of hydroxypropylation will directly affect the solubility, film-forming properties, and role of HPMC in certain formulations.
High hydroxypropyl content: This type of HPMC has better solubility and lower viscosity, and is often used to prepare lightweight coatings, drug capsules, and some functional foods.
Low hydroxypropylation: HPMC with low hydroxypropylation has poor solubility but good adhesion, and is suitable for applications that require stability, such as drug sustained-release systems or certain building materials.
4. Classification by water solubility
The solubility of different grades of HPMC in water varies greatly. According to the different dissolution rates, it can be divided into:
Instant-soluble HPMC: This type of HPMC has a higher dissolution rate and is usually used in fast-dissolving preparations, such as thickeners in drugs or foods.
Slow-soluble HPMC: This type of HPMC has a slower dissolution rate and is suitable for formulations that require a longer time to dissolve, such as certain sustained-release drug preparations or long-term moisturizing cosmetic products.
5. Specific classification of application areas
According to different application areas, HPMC can also be divided into:
Pharmaceutical grade HPMC: used in pharmaceutical preparations, especially drug sustained-release preparations, tablet coatings, capsule fillers, etc.
Food grade HPMC: used in the food industry, such as as a thickener, emulsifier, stabilizer, etc.
Industrial grade HPMC: including HPMC for the construction industry (for example, additives for cement and mortar), HPMC for coatings, etc.
Cosmetic grade HPMC: used in personal care products such as facial cleansers, moisturizers, hair sprays, etc.
The grading of hydroxypropyl methylcellulose is very detailed and can be selected according to different parameters. The main classification criteria include viscosity, degree of methylation, degree of hydroxypropylation, water solubility, etc. Different industries and application requirements have different specifications for HPMC, so when choosing, it is necessary to determine the appropriate product grade according to the actual use.
Post time: Mar-15-2025