Differences and application areas of HPMC and RDP
There are significant differences in properties, uses and preparation methods between HPMC (hydroxypropyl methylcellulose) and RDP (redispersible powder).
1.Properties
Properties of HPMC: HPMC is a white or off-white powder, soluble in water and some solvents, such as ethanol/water, propanol/water, trichloroethane, etc. Its aqueous solution has surface activity, high transparency, stable performance, and is not affected by pH value.
Properties of RDP: RDP is a dry powdery material that can be redispersed into glue when exposed to water and has good adhesion and water resistance.
2. Applications
HPMC is widely used in many fields:
a. Construction industry: used in mortar, tile adhesive, waterproof materials, etc.
b. Pharmaceutical industry: used as thickener, solvent and sustained-release agent for tablets.
c. Food industry: used in plant protein beverages, dairy products, candies, etc..
d. Cosmetics Industry: As emulsifier, thickener and moisturizer.
e. Drugs: used to prepare plant capsules, coating materials, sustained-release agents and controlled-release agents, etc..
RDP uses: Mainly used in the construction industry, such as dry-mix mortar, tile adhesive, wallpaper adhesive, etc.
3. Preparation method
Preparation method of HPMC: HPMC is usually produced by the reaction of methylcellulose and propylene oxide. The specific steps include dissolving methylcellulose in water, then adding propylene oxide for etherification reaction, and finally obtaining the product through separation, drying and other processes.
Preparation method of RDP: The preparation of RDP involves spray drying the emulsion into powder, which can be redispersed into a glue when exposed to water. The specific process includes emulsion preparation, spray drying, powder collection and packaging and other steps
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