Hydroxypropyl methylcellulose (INN name: Hypromellose), also simplified as hypromellose (hydroxypropyl methylcellulose, abbreviated as HPMC), is a variety of nonionic cellulose mixed ethers. It is a semi-synthetic, inactive, viscoelastic polymer commonly used as a lubricant in ophthalmology, or as an excipient or excipient in oral pharmaceuticals, and is commonly found in various commercial products.

As a food additive, hypromellose can play the following roles: emulsifier, thickener, suspending agent and substitute for animal gelatin. Its code (E-code) in the Codex Alimentarius is E464.

Chemical properties:

The finished product of hydroxypropyl methylcellulose is white powder or white loose fibrous solid, and the particle size passes through a 80-mesh sieve. The ratio of the methoxyl content to the hydroxypropyl content of the finished product is different, and the viscosity is different, so it becomes a variety of varieties with different performances. It has the characteristics of being soluble in cold water and insoluble in hot water similar to methyl cellulose, and its solubility in organic solvents exceeds that of water. It can be dissolved in anhydrous methanol and ethanol, and can also be dissolved in chlorinated hydrocarbons such as dichloro methane, trichloroethane, and organic solvents such as acetone, isopropanol, and diacetone alcohol. When dissolved in water, it will combine with water molecules to form a colloid. It is stable to acid and alkali, and is not affected in the range of pH=2~12. Hypromellose, although non-toxic, is flammable and reacts violently with oxidizing agents.

The viscosity of HPMC products increases with the increase of concentration and molecular weight, and when the temperature rises, its viscosity begins to decrease. When it reaches a certain temperature, the viscosity suddenly rises and gelation occurs. height of. Its aqueous solution is stable at room temperature, except that it can be degraded by enzymes, and its general viscosity has no degradation phenomenon. It has special thermal gelation properties, good film-forming properties and surface activity.

Making:

After the cellulose is treated with alkali, the alkoxy anion generated by the deprotonation of the hydroxyl group can add propylene oxide to generate hydroxypropyl cellulose ether; it can also condense with methyl chloride to generate methyl cellulose ether. Hydroxypropyl methylcellulose is produced when both reactions are carried out simultaneously.

Using:

The use of hydroxypropyl methylcellulose is similar to that of other cellulose ethers. It is mainly used as a dispersant, suspending agent, thickener, emulsifier, stabilizer and adhesive in various fields. It is superior to other cellulose ethers in terms of solubility, dispersibility, transparency and enzyme resistance.

In the food and pharmaceutical industry, it is used as an additive. It is used as an adhesive, thickener, dispersant, Emollient, stabilizer and emulsifier. It has no toxicity, no nutritional value, and no metabolic changes.

In addition, HPMC has applications in synthetic resin polymerization, petrochemicals, ceramics, papermaking, leather, cosmetics, coatings, building materials and photosensitive printing plates.