Hydroxypropyl methylcellulose (HPMC) is an important cellulose ether with a wide range of applications, mainly in the fields of construction, medicine, food, etc. According to different processing methods, HPMC can be divided into surface-treated and untreated types.
1. Differences in production processes
Untreated HPMC
Untreated HPMC does not undergo special surface coating treatment during the production process, so its hydrophilicity and solubility are directly retained. This type of HPMC swells rapidly and begins to dissolve after contact with water, showing a rapid increase in viscosity.
Surface-treated HPMC
Surface-treated HPMC will have an additional coating process added after production. Common surface treatment materials are acetic acid or other special compounds. Through this treatment, a hydrophobic film will be formed on the surface of HPMC particles. This treatment slows down its dissolution process, and it is usually necessary to activate the dissolution by uniform stirring.
2. Differences in solubility properties
Dissolution characteristics of untreated HPMC
Untreated HPMC will start to dissolve immediately after contact with water, which is suitable for scenarios with high requirements for dissolution speed. However, since rapid dissolution is prone to form agglomerates, the feeding speed and stirring uniformity need to be controlled more carefully.
Dissolution characteristics of surface-treated HPMC
The coating on the surface of surface-treated HPMC particles takes time to dissolve or destroy, so the dissolution time is longer, usually several minutes to more than ten minutes. This design avoids the formation of agglomerates and is particularly suitable for scenes that require large-scale rapid stirring or complex water quality during the addition process.
3. Differences in viscosity characteristics
Surface-treated HPMC will not release viscosity immediately before dissolution, while untreated HPMC will quickly increase the viscosity of the system. Therefore, in cases where viscosity needs to be gradually adjusted or the process needs to be controlled, the surface-treated type has more advantages.
4. Differences in applicable scenarios
Unsurface-treated HPMC
Suitable for scenes that require rapid dissolution and immediate effect, such as instant capsule coating agents in the pharmaceutical field or rapid thickeners in the food industry.
It also performs well in some laboratory studies or small-scale production with strict control of the feeding sequence.
Surface-treated HPMC
It is widely used in the construction industry, for example, in dry mortar, tile adhesive, coatings and other products. It is easy to disperse and does not form agglomerates, which is particularly suitable for mechanized construction conditions.
It is also used in some pharmaceutical preparations that require sustained release or food additives that control the dissolution rate.
5. Price and storage differences
The production cost of surface-treated HPMC is slightly higher than that of untreated, which is reflected in the difference in market price. In addition, the surface-treated type has a protective coating and has lower requirements for the humidity and temperature of the storage environment, while the untreated type is more hygroscopic and requires more stringent storage conditions.
6. Selection basis
When choosing HPMC, users need to consider the following points according to specific needs:
Is the dissolution rate important?
Requirements for the viscosity growth rate.
Whether the feeding and mixing methods are easy to form agglomerates.
The industrial process of the target application and the final performance requirements of the product.
Surface-treated and non-surface-treated HPMC have their own characteristics. The former improves the ease of use and operational stability by changing the dissolution behavior, and is suitable for large-scale industrial production; the latter retains a high dissolution rate and is more suitable for the fine chemical industry that requires a high dissolution rate. The choice of which type should be combined with the specific application scenario, process conditions and cost budget.
Post time: Nov-20-2024