What Is Phthalic Anhydride/Butyl Benzoic Acid/Propylene Glycol Copolymer?
Phthalic Anhydride/Butyl Benzoic Acid/Propylene Glycol Copolymer is a man-made polymer created by combining three building blocks: phthalic anhydride, butyl benzoic acid and propylene glycol. When these raw materials react they form long chain molecules that act like a flexible film once they dry on the skin or hair. The ingredient first appeared in nail polishes and hair sprays several decades ago as chemists searched for safer, more reliable film formers than the harsh resins used at the time. Its success in those products soon led to wider use in makeup and skin care.
Manufacturing starts with phthalic anhydride, a powder derived from petroleum or coal tar. It is mixed with butyl benzoic acid, an ester made from benzoic acid and butyl alcohol, and with propylene glycol, a clear liquid that comes from propylene oxide. Under controlled heat the three ingredients react, water is removed and the resulting thick resin is cooled and ground into a fine powder or supplied as a viscous solution ready for formulators.
Today you will most often find this copolymer in nail lacquers, liquid eyeliners, mascaras, long-wear foundations, hair styling sprays, peel-off face masks and transfer-resistant lip products. In these formulas it creates a smooth film that boosts staying power while also tweaking thickness so the product feels just right when spread or sprayed.
Phthalic Anhydride/Butyl Benzoic Acid/Propylene Glycol Copolymer’s Cosmetic Benefits/Uses
Here is how this ingredient improves the performance and feel of beauty products
- Film forming: Leaves behind a thin flexible layer that locks color in place, resists water and helps makeup last longer without smudging or flaking
- Viscosity controlling: Adjusts thickness so creams are neither runny nor too stiff, keeps sprays clear of clogs and ensures an even coat during application
Who Can Use Phthalic Anhydride/Butyl Benzoic Acid/Propylene Glycol Copolymer
This copolymer is generally well tolerated by all skin types including dry, oily, combination and even most sensitive complexions because it sits on the surface rather than soaking in and has no active biological effect. People with a known allergy to synthetic resins or those who struggle with eczema flare-ups should approach cautiously as any film former can occasionally trap sweat and heat, leading to irritation in compromised skin.
The ingredient is synthesized from petrochemical sources with no animal-derived raw materials or processing aids so it is suitable for vegans and vegetarians.
Current safety data show no reproductive or developmental concerns so products containing this polymer are considered acceptable for use during pregnancy or while breastfeeding. This is not medical advice and anyone who is pregnant or nursing should discuss all personal care products with a doctor to be sure they meet individual needs.
The copolymer does not absorb ultraviolet light and does not make skin more sensitive to the sun. It is also fragrance free and colorless which reduces the chance of fragrance-related sensitivity.
Potential Side Effects/Adverse Reactions
Responses to topical Phthalic Anhydride/Butyl Benzoic Acid/Propylene Glycol Copolymer differ from person to person. The issues listed below are possible but uncommon when the ingredient is used at the levels typically found in cosmetics.
- Contact dermatitis presenting as redness itching or mild swelling
- Temporary eye stinging if the product accidentally gets into the eyes
- Respiratory irritation from inhaling fine mist when the ingredient is delivered through aerosol hair or face sprays
- Rare allergic reaction in individuals sensitized to phthalic compounds or benzoic acid derivatives
- Build-up that makes hair feel coated or heavy if wash-off is inadequate
If any of these reactions occur discontinue use immediately and seek guidance from a healthcare professional.
Comedogenic Rating
Rating: 1 out of 5 – This polymer is large in size, non greasy and tends to stay on the surface rather than seeping into pores, so it has very little chance of clogging them. While any film former can trap sweat or debris if cleansing is inadequate, the ingredient itself is not oily or waxy which keeps its pore-blocking potential low.
Suitable for acne-prone or breakout-prone skin in most cases.
Because it is usually paired with quick-dry solvents in nail, eye and hair products, the overall formula may feel tight or drying rather than greasy, further reducing clogging concerns.
Summary
Phthalic Anhydride/Butyl Benzoic Acid/Propylene Glycol Copolymer serves two key jobs in cosmetics: it forms a clear flexible film that locks makeup, color and style in place and it tweaks viscosity so products glide, spray or spread with the right consistency. It does this by linking its long chain molecules together as the formula dries, creating an even mesh while its bulky structure thickens the base without heaviness.
The ingredient enjoys steady use in long-wear nail lacquers, mascaras, liquid eyeliners and certain hair sprays though it is less common in basic moisturizers or cleansers where strong film formation is not needed.
Current research and decades of consumer exposure show it to be low risk for toxicity, irritation and pore clogging, making it a generally safe option for most users. As always, anyone trying a new product that contains this or any other unfamiliar ingredient should perform a quick patch test to confirm personal compatibility.