Perfluorobutane sulfonic acid potassium salt CAS No. : 29420-49-3 Formula: n-C4F9SO3K Molecular Weight: 338.2 Appearance: white or slightly yellow powder Density: 0.690 pH: 5-7 Melting point: 300 Content: e 98% Application: It is a kind of perfluoro anion surfactant and has the general characters of fluoro surfactant. It is widely used as inflaming retardant for synthetic materials, especially for polycarbonate.