Process for coating a glass substrate with an aqueous fluoropolymer coating

A process for forming a fluoropolymer coating on a substrate comprising the steps of:

• a) coating said substrate on at least one side or at least one edge with a primer composition comprising:
• 1) at least one hydroxy-functional polyurethane,
• 2) at least one polyisocyanate,
• 3) at least one organosilane coupling agent,
• 4) optionally an antioxidant
• 5) optionally one or more additives selected from the group consisting of coalescent agents, pigments, dyes, wetting agents, UV absorbers, and heat stabilizers;
• b) curing said primer composition to leave 15-90% of unreacted isocyanate or hydroxyl functional groups;
• c) coating said primered substrate with an aqueous hydroxy-functional fluoropolymer composition comprising:
• 1) a hydroxy-functional fluoropolymer,
• 2) a hydrophilic aliphatic polyisocyanate,
• 3) optionally one or more additives selected from the group consisting of pigments, coalescent agents, wetting agents, UV absorbers, and heat stabilizers;
• and
• d) curing said coated substrate.