Coating installation of an industrial mass production coating line including non-aqueous solvent composition as barrier liquid

A coating installation of an industrial mass production coating line for the application of a water-borne two-component polyurethane coating comprising:

• storage tanks for an aqueous base component and a non-aqueous hardener component;
• circulation lines for the components from the respective storage tanks,
• a mixer for receiving the aqueous base component and the non-aqueous hardener component to form a water-borne two-component polyurethane coating composition and an entrance to the mixer with a connection between each circulating line and the entrance to the mixer;
• a release valve for the non-aqueous hardener component in the connection between the circulating line for the non-aqueous hardener component and the entrance to the mixer;
• a spray-application device for spraying the water-borne two-component polyurethane coating composition to form the water-borne two-component polyurethane coating and connecting pipework downstream of the release valve for the non-aqueous hardener;
• wherein the coating installation downstream of the non-aqueous hardener release valve including the mixer, the spray-application devices, and connecting pipework is filled with a non-aqueous solvent composition comprising:
• 0 to 10 wt. % of N-alkyl pyrrolidone,
• 0 to 5 wt. % of dimethyl sulfoxide,
• 10 to 50 wt. % of γ-butyrolactone,
• 10 to 50 wt. % of at least one monoalcohol,
• 10 to 60 wt. % of at least one organic solvent inert towards isocyanate groups, other than γ-butyrolactone, other than N-alkyl pyrrolidone, and consisting of carbon, hydrogen, and oxygen and, optionally, nitrogen, and
• 0 to 10 wt. % of at least one additive.