What Is Phthalic Anhydride/Trimellitic Anhydride/Glycols Copolymer?
Phthalic Anhydride/Trimellitic Anhydride/Glycols Copolymer is a synthetic polymer created by reacting phthalic anhydride and trimellitic anhydride, two ring-shaped acids derived from petrochemical sources, with small alcohol molecules called glycols. The result is a large stable molecule that behaves like a flexible plastic film when it dries on the skin or hair.
The polymer traces its cosmetic use back to the late twentieth century when formulators were looking for lightweight non-tacky film formers to improve the longevity of color cosmetics. By adjusting the ratio of the two anhydrides and the types of glycols, manufacturers can fine-tune the hardness, gloss and solubility of the final polymer, making it suitable for a variety of beauty products.
Industrial production starts with purified phthalic and trimellitic anhydrides, which are melted and combined with ethylene glycol and neopentyl glycol under controlled heat and vacuum. The reaction links the molecules in long chains, then the molten polymer is cooled, chipped and dissolved in water or alcohol to create a user-friendly solution for cosmetic labs.
You will most often find this ingredient in long-wear makeup like liquid foundations, eyeliners and mascaras, as well as in nail polish, hair styling sprays, peel-off face masks and some sunscreens where a flexible, water-resistant film is desirable.
Phthalic Anhydride/Trimellitic Anhydride/Glycols Copolymer’s Cosmetic Benefits/Uses
In skincare and makeup formulas this polymer serves two key technical roles that translate into practical consumer benefits.
- Film forming – When the product dries the polymer forms a thin even layer that locks pigments in place, boosts water resistance, helps fragrances last longer and provides a smooth glossy finish without a heavy feel
- Viscosity controlling – It thickens liquids just enough to keep particles suspended and prevent separation, giving creams or sprays a consistent texture that spreads easily and dries evenly
Who Can Use Phthalic Anhydride/Trimellitic Anhydride/Glycols Copolymer
This polymer is generally considered suitable for most skin types including dry, normal and oily skin because it is non-sensitising and sits on the surface rather than penetrating deeply. Sensitive or eczema-prone skin usually tolerates it well, though products with high solvent levels (like nail polish removers) could still sting compromised skin.
Because the material is synthesized entirely from petrochemical feedstocks and not derived from animals it is acceptable for vegans and vegetarians.
No data link the ingredient itself to pregnancy-related risks so it is viewed as safe for people who are pregnant or breastfeeding when used as directed in cosmetics. This is not medical advice and anyone who is pregnant or nursing should discuss any skincare product with their physician to be safe.
The polymer does not absorb UV light so it does not cause photosensitivity. It is also fragrance-free and colorless which lowers the chance of irritation for fragrance-sensitive users.
Potential Side Effects/Adverse Reactions
Individual reactions to topical Phthalic Anhydride/Trimellitic Anhydride/Glycols Copolymer can differ from person to person. The points below describe potential side effects that are possible but not expected for the average user when the ingredient is formulated and used correctly.
- Mild skin redness or itching
- Allergic contact dermatitis in those already sensitised to phthalic compounds
- Eye irritation if the liquid or flakes are accidentally rubbed into the eyes
- Respiratory discomfort when inhaled as overspray from aerosol hair or setting sprays
- Temporary pore blockage if very thick layers are left on acne-prone skin without proper cleansing
If any of these reactions occur discontinue use and seek advice from a healthcare professional
Comedogenic Rating
Rating: 1/5 (very low)
This polymer forms a lightweight surface film and its large molecular size keeps it from settling inside pores, so the likelihood of clogging is minimal. A score of 1 rather than 0 is given because very heavy layers left on oily skin could trap debris if the product is not removed thoroughly.
With such a low tendency to block pores, the ingredient is considered suitable for people who are prone to acne or breakouts.
Keep in mind the final comedogenicity of a formula also depends on the other ingredients paired with the polymer, especially rich oils or butters.
Summary
Phthalic Anhydride/Trimellitic Anhydride/Glycols Copolymer serves mainly as a film former and mild thickener. After application it dries into a flexible mesh that anchors pigments, boosts gloss, increases water resistance and helps products stay put. Its long chain structure also adds just enough body to liquids so solids stay evenly dispersed for a smooth streak-free finish.
The polymer is not the most famous ingredient but it has a devoted following among formulators of long wear makeup, nail polish and hair sprays because it delivers dependable hold without a heavy feel.
Safety assessments show low irritation and virtually no absorption through skin, making it a low-risk choice for most users. As with any new cosmetic though, patch testing is recommended to make sure your skin agrees with the full formula.