Fluorinated Copolymer Repellent Coating for Wash and Rain Durability

The patent changes the chemical composition parameters by incorporating specific monomers (monomer (a) with polyfluoroalkyl group and monomer (b) with carboxyl group) in controlled proportions. The carboxyl group content is specifically adjusted to 0.1-10 mmol/g to optimize both water/oil repellency and heavy-rain durability, resolving the contradiction between initial repellency and durability under heavy rain exposure.

The patent creates a composite polymer structure by copolymerizing monomer (a) containing polyfluoroalkyl groups with monomer (b) containing carboxyl groups. This composite material combines the water/oil repellent properties of polyfluoroalkyl groups with the durability-enhancing properties of carboxyl groups, achieving both excellent repellency and heavy-rain durability simultaneously.

The patent optimizes the molecular weight parameters of the polymer, specifying Mn (number average molecular weight) of 1,000-100,000 and Mw (weight average molecular weight) of 10,000-1,000,000. This parameter control ensures the polymer maintains its repellent properties through washing while preventing excessive molecular weight that would reduce effectiveness.

The composite polymer structure combining polyfluoroalkyl-containing monomer and carboxyl group-containing monomer provides enhanced wash durability. The carboxyl groups contribute to better adhesion and stability during washing, while the polyfluoroalkyl groups maintain the repellent function, achieving both wash durability and sustained repellency.