What Is Polyurethane-66?
Polyurethane-66 is a modern synthetic polymer created by linking together smaller chemical building blocks called isocyanates and polyols. The process starts with 1,4-butanediol that has been reacted with about 28 units of butylene oxide, forming a flexible polyol chain. This chain is then combined with two specialty isocyanates— isophorone diisocyanate and 1,3-bis(isocyanomethyl)cyclohexane. Finally the ends are capped with hydroxybutyl acrylate, giving the finished material useful bonding sites. Work on urethane chemistry dates back to the 1930s, but lighter and more flexible versions like Polyurethane-66 gained cosmetic interest in the last few decades as brands searched for film formers that feel weightless on skin and hair.
Production happens in closed reactors where temperature and mixing speed are closely controlled. Each raw material is added in sequence so the chains grow to a set length and the final polymer stays consistent from batch to batch. Strict filtering removes any unreacted monomers, leaving behind a pure, high-molecular-weight powder or dispersion that is safe for topical use.
Because it forms an invisible, flexible film, Polyurethane-66 shows up in a variety of products. You may find it in long-wear makeup for better adhesion, in peel-off masks to create an even layer, in hair styling sprays for lasting hold, and in moisturizers or anti-aging creams where it helps pigments and actives stay evenly spread on the skin.
Polyurethane-66’s Cosmetic Benefits/Uses
This ingredient is valued mainly for one key job in formulas.
Binding: Polyurethane-66 acts like a gentle glue inside a product, holding powders, pearls, pigments, and other ingredients together. It helps makeup cling to skin even in humid conditions, keeps peel-off masks from cracking, and lets hair sprays form a flexible net that resists flaking. By improving adhesion it boosts wear time and overall performance without making the texture feel heavy or sticky.
Who Can Use Polyurethane-66Because it is an inert high-molecular-weight film former, Polyurethane-66 is generally well tolerated by all skin types including oily, dry, combination and even most sensitive skin. Its flexible film keeps water loss in check without trapping excess oil or causing a heavy feel, making it a versatile choice across a wide audience. Extremely reactive or allergy-prone individuals should still watch for any personal sensitivity, but no skin type is outright contraindicated.
Polyurethane-66 is fully synthetic and contains no animal-derived raw materials, so products using it are typically suitable for vegans and vegetarians.
The molecule is too large to penetrate deeply and has no known hormonal activity, so it is not expected to pose risk to women who are pregnant or breastfeeding. This is not medical advice; anyone who is expecting or nursing should show the ingredient list of any cosmetic product to their healthcare provider for personalized guidance.
Polyurethane-66 does not make skin more likely to burn or darken in sunlight, so it is not considered photosensitizing. It also plays well with most other cosmetic actives and does not interfere with makeup removal when a regular cleanser or makeup remover is used.
Potential Side Effects/Adverse Reactions
Reactions to topical Polyurethane-66 vary from person to person. The issues listed below are only potential side effects and are unlikely to be the average user’s experience when the ingredient is used correctly in a finished product.
- Mild skin irritation such as redness or itching in highly sensitive individuals
- Rare allergic contact dermatitis if trace isocyanate residues remain from manufacturing
- Temporary eye or respiratory irritation when inhaled from aerosol hair sprays
- Build-up on hair shafts leading to dullness if not cleansed properly over time
If any discomfort or visible reaction occurs while using Polyurethane-66 or a product that contains it, stop use immediately and seek guidance from a qualified healthcare professional.
Comedogenic Rating
Rating: 1 / 5
Polyurethane-66 forms an airy, breathable film that sits on top of the skin rather than seeping into pores, so it has very little tendency to trap sebum or debris. Its large molecular size also keeps it from lodging inside follicles. Because of this, the ingredient earns a low comedogenic score of 1. In most formulas it poses minimal risk for clogging, making it generally suitable for people prone to acne or breakouts. Only in very heavy or poorly cleansed layers could it possibly contribute to surface build-up.
Summary
Polyurethane-66 is mainly a binder and film former. By linking pigments, powders and styling agents into a flexible mesh, it boosts adhesion, extends wear time and adds a smooth feel without weighing skin or hair down. You will spot it in long-wear makeup, peel-off masks, hair sprays and the occasional skin cream.
The polymer is not as widespread as classics like PVP or acrylates, but interest is growing as brands look for lightweight options that resist humidity and flaking.
Safety data show the ingredient is non-sensitizing for most users, free of hormonal activity and unlikely to clog pores. While reactions are rare, it is always smart to patch test any new product to make sure it plays nicely with your individual skin.