Quaternium-91 (U.S. Patent US 6,540,947 B2) is a patented dialkyl imidazoline quaternary ammonium salt.
With its strong cationic electrostatic adsorption properties, it attaches precisely to damaged hair cuticles to form a breathable protective film, filling cracks and smoothing cuticles.
It locks in post-dye pigment molecules for a long time to resist fading and yellowing, while significantly improving wet and dry combability, softness and shine of hair. It solves the pain points of ordinary conditioning ingredients that "lose effectiveness upon rinsing" and offer short-lasting repair, achieving professional hair care effects that combine color protection, repair and smoothness in one.