by Hydrogenated Polyisobutene: An In-depth Look at This Common Ingredient
What is it?
Hydrogenated polyisobutene is a synthetic compound produced through the polymerization of isobutylene. Chemically, it is a saturated hydrocarbon polymer meaning all carbon-carbon double bonds have been converted to single bonds through the addition of hydrogen. This process, known as hydrogenation, increases the stability and shelf life of the compound.
Production and Structure
Industrially, isobutylene monomers are polymerized in the presence of a catalyst under controlled conditions to form long chains of polyisobutene. To stabilize the polymer, hydrogen is added across all remaining carbon-carbon double bonds. This results in a saturated, single chain hydrocarbon with the general formula [C4H8]nH.
The molecular weight and structure of hydrogenated polyisobutene can vary depending on the production process but it typically exists as a waxy solid or thick liquid. The polymer backbone is completely saturated and linear with methyl side groups attached to every other carbon. This structure gives the compound its lubricating and moisturizing properties.
Common Uses and Applications
Due to its stable, non-reactive nature, HPBI finds wide application in personal care products and cosmetics. Some of its most common uses include:
– Moisturizer in Skin Creams – As an emollient, it helps to soften and hydrate skin without feeling greasy. HPBI forms an invisible, breathable film to lock in moisture.
– Lip Balm Ingredient – It gives a slick, protective barrier to soothe and condition lips. Being oil-soluble, it melts on contact with lips.
– Thickening Agent – Used to adjust viscosity in lotions, gels and other formulations. Even in small amounts, it improves the texture and appearance.
– Make-up Bases – Found in foundations, concealers and other color cosmetics to provide a smooth, creamy feel.
– Sunscreen Ingredient – Acts as a lubricant to ease application of sun protection formulas on the skin.
Beyond cosmetics, HPBI also sees application as a lubricant additive in industrial greases and metalworking fluids. Its waxy texture releases cleanly under pressure.
Safety and Regulatory Status
Regulatory bodies list HPBI as generally safe for use in cosmetics and personal care. The Cosmetic Ingredient Review (CIR) Expert Panel concluded it is non-toxic and non-irritating when applied topically.
It is properly classified by the Food and Drug Administration (FDA) as non-comedogenic, meaning it does not block or congest pores. Manufacturers are able to freely formulate with hydrogenated polyisobutene within legal limits without restrictions.
The International Nomenclature of Cosmetic Ingredients (INCI) name registered is Polyisobutene. No known safety issues or side effects have been associated with its use at low concentrations. Rare cases of allergic contact dermatitis have been reported.
Alternative Formulations
While HPBI remains popular as an inexpensive moisturizing ingredient, some manufacturers are exploring greener alternatives. Natural oils high in fatty acids like coconut, jojoba or olive oils can mimic its emollient properties without the non-renewable petroleum source.
Plant butters and waxes from shea, cocoa or mango are also tried as eco-friendly substitutes. Their fatty acid profiles contribute similar conditioning effects. Synthetic alternatives include mineral oils or silicone-based emollients, though these raise sustainability concerns of their own.
For some applications, propylene glycol or glycerin provide hydration while maintaining a lighter, non-occlusive feel on skin compared to HPBI. Formulators must weigh various technical performance factors in determining the best emollient system.
Summary
In summary, hydrogenated polyisobutene is a ubiquitous, cost-effective ingredient prevalent in skin care, cosmetics and personal care products due to its ability to moisturize without leaving a greasy after-feel. Through hydrogenation, it achieves exceptional stability making it well-suited for long shelf-lives. Manufacturers continue exploring renewable substitutes, though HPBI remains popular due to functionality and regulatory approval. When used prudently in formulated products, it poses very low risk to consumer safety.
