Hydroxypropylcellulosa

Hydroxypropylcellulosa, commonly known as hydroxypropyl cellulose (HPC), is a cellulose ether derived from cellulose by etherification with propylene oxide to introduce hydroxypropyl groups. The degree of substitution and molecular weight vary among grades, yielding a range of solubilities and viscosities. The resulting polymer is water-soluble and forms clear, viscous solutions that can function as thickeners, binders, suspending agents, and film-formers in a variety of formulations.

Manufacture and properties: HPC is produced from cellulose derived from wood pulp or cotton. Under alkaline conditions, cellulose reacts with propylene oxide to form hydroxypropyl substituents, producing a non-ionic, hydrophilic polymer. It readily dissolves in cold water to yield translucent, viscous solutions. Viscosity is highly dependent on grade, concentration, temperature, and the presence of electrolytes, allowing HPC to be tailored for specific applications. It is compatible with many surfactants, plasticizers, and solvents, though high salt levels or extreme temperatures can influence its rheology.

Applications: In the food industry, HPC (often listed as E464) acts as a thickener and stabilizer. In cosmetics and personal care, it serves as a thickener and film-former in gels, creams, and lotions. In pharmaceuticals, HPC is a common excipient used as a binder in tablets and as a film-coating polymer for controlled-release and taste-masking coatings. It is also employed as a binder and thickener in topical formulations and certain adhesive or suspension systems.

Safety and regulation: HPC is widely regarded as safe for its approved uses. It is non-toxic, generally regarded as inert in typical formulations, and approved as a food additive and pharmaceutical excipient in many jurisdictions. Handling follows standard guidelines for cosmetic, food, and pharmaceutical ingredients.

See also: Methylcellulose, Carboxymethylcellulose.