Abstract: Disclosed herein are a primer coating system including at least two components A) and B) being different and separate from one another, where component A) includes at least constituent a2) and at least one condensation product a3), where component B) includes at least one organic constituent b2) bearing on average two or more NCO-groups, a primer coating composition obtained by mixing at least components A) and B) with each other or a 1K primer coating composition including the condensation product a3), a use method of using the primer coating composition for improving water and/or moisture resistance of cured coating films and multilayer coating obtained therefrom, a method of coating a substrate by at least applying the primer coating composition, a coated substrate obtained therefrom, a method of preparing a multilayer coating system including at least one primer coating film obtained from the primer coating composition, and a multilayer coating system.

Abstract: Disclosed herein are a multilayer coating system present on a substrate including at least three layers L1 to L3, layer L1 being obtained from a primer coating composition, which is obtained from a primer coating system including at least two components A) and B) separated from each other, where component A) inter alia includes at least one constituent a2), which is at least one (meth)acrylic polymer, which has been modified with at least one chlorinated polyolefin, where the polymer contains functional groups, that are reactive towards NCO-groups, layer L2 being obtained from a basecoat composition, and layer L3 being obtained from a clearcoat composition, a method of preparing a multilayer coating system making use of the aforementioned primer coating system, and a kit-of-parts including separated from one another at least the primer coating system and a clearcoat composition or a clearcoat system.