Va-grapes,
You might get some help from companies which make IR reflective mirrors, such as would be used in IR LASERS, such as Carbon Dioxide gas LASERS. They may be able to create an efficient IR reflecting surface by layering various optical materials. This would be very expensive and would not be useful where paint could be used, but they might have some info you can use.
Richvangenr1,
NASA uses gold foil as an IR reflector on its spacecraft, so presumably it is an efficient reflector of IR. If a metal is made into a very fine powder it can become black in appearance. Platinum is sometimes used like this. Maybe a coating of powder made from an efficient IR reflective metal such as gold can form the type of coating you're looking for.