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Film Former

ISOBUTYLENE/STYRENE COPOLYMER

CAS 9011-12-5
78

Safety score · 0–100

Fine

Derived from EU CosIng regulatory status, PubChem hazard data and published research. How we score.

A hydrocarbon copolymer of isobutylene and styrene used as a film former and viscosity modifier. Cured polymer is inert; the styrene monomer is an IARC 2A probable carcinogen, so residual control is the safety lever.

Skin benefits

  • Inert hydrocarbon copolymer
  • Film-forming and viscosity control
  • Stable across formulations

Known concerns

  • Residual styrene monomer — IARC 2A probable carcinogen
  • Not biodegradable
  • Modern grades control styrene to <50 ppm

References

EU

EU CosIng database

European Commission cosmetic ingredient registry: regulatory status, restrictions, authorised functions.

Related film formers

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This profile is for educational purposes and does not constitute medical advice. Regulatory status and scientific understanding evolve, so always read the physical product label and consult a healthcare professional for personal concerns.