Hydroxy-propyl Methylcellulose, HPMC or Hydroxypropyl Methylcellulose
The name describes the structure of the molecule:
- "Hydroxy-propyl": Represents the presence of hydroxyl groups (OH) attached to the propyl group (-CH2-CH2-CH2-) in the molecule. These hydroxypropyl groups confer hydrophilic properties to HPMC.
- "Methylcellulose": Indicates the presence of methyl groups (-CH3) attached to cellulose. Cellulose is a natural polymer composed of glucose units. The substitution of some hydroxyl groups with methyl groups gives HPMC flow modification and film-forming properties.
Therefore, the name "Hydroxypropyl Methylcellulose" indicates that the molecule is a modified cellulose with hydroxypropyl groups and methyl groups, which contribute to its specific properties.
The synthesis process takes place in different steps:
- Cellulose extraction. Cellulose is extracted from natural sources such as wood or cotton. In this phase, cellulose is separated from other impurities present in the starting material.
- Alkaline treatment. The extracted cellulose undergoes treatment with an alkaline solution. This helps remove impurities and unwanted components, purifying the cellulose.
- Propylene oxide treatment. The purified cellulose is treated with propylene oxide. This reacts with the hydroxyl groups present on cellulose, substituting some hydroxyl groups with hydroxypropyl groups.
- Methylation. After the propylene oxide treatment, the hydroxypropylated cellulose undergoes a methylation reaction. This is done by adding methanol and a strong base, such as sodium hydroxide. During this reaction, the remaining hydroxyl groups are replaced by methyl groups, forming HPMC.
- Purification. The obtained HPMC is purified to remove any residual impurities. This can be done through washing, filtration, or precipitation processes.
- Drying and grinding. After purification, HPMC is dried to remove residual moisture and then ground into a fine powder.
- Packaging. Finally, HPMC is packaged in suitable containers for industrial or commercial distribution and use.
What it is for and where
It is widely used in various industries due to its film-forming, water-retaining, oil-resistant, insulating, and lubricating properties.
Cosmetics
- Antistatic agent. Static electricity build-up has a direct influence on products and causes electrostatic adsorption. The antistatic ingredient reduces static build-up and surface resistivity on the surface of the skin and hair.
- Binder agent. Ingredient that is used in cosmetic, food and pharmaceutical products as an anti-caking agent with the function of making the product in which it is incorporated silky, compact and homogenous. The binder, either natural such as mucilage, gums and starches or chemical, may be in the form of a powder or liquid.
- Emulsion stabiliser. Emulsions are thermodynamically unstable. Emulsion stabilisers improve the formation and stability of single and double emulsions. as well as their shelf-life. It should be noted that in the structure-function relationship, the molar mass of the ingredient used plays an important role.
- Film-forming agent. It produces, upon application, a very thin continuous film with an optimal balance of cohesion, adhesion and stickiness on skin, hair or nails to counteract or limit damage from external phenomena such as chemicals, UV rays and pollution.
- Surfactant - Cleansing agent. Cosmetic products used to cleanse the skin utilise the surface-active action that produces a lowering of the surface tension of the stratum corneum, facilitating the removal of dirt and impurities.
- Viscosity control agent. It controls and adapts, Increasing or decreasing, viscosity to the required level for optimal chemical and physical stability of the product and dosage in gels, suspensions, emulsions, solutions.
Food
HPMC is used as a food additive. It functions as an emulsifier, coating agent, stabilizer, thickening agent, and water-retaining agent.
Pharmaceutical
HPMC is used as an excipient in tablets and capsules. It enhances the stability and drug release control.
Construction industry
HPMC is used as an additive in mortars, adhesives, and plasters. It improves workability and water retention.
CAS 9004-65-3
