Retroreflective transfer sheet material

A transfer sheet material for forming retroreflective graphic images on a substrate, the sheet material comprising:

• a) a monolayer of transparent microspheres;
• b) a color layer printed over the microspheres in a first graphic segment of the sheet material in an imagewise pattern, the color layer comprising a transparent colorant in a transparent resin;
• c) a reflective layer printed over the microspheres in a second graphic segment of the sheet material in an imagewise pattern in such a manner that any overlapping areas of the first and second graphic segments are characterized by the color layer being disposed between the microspheres and the reflective layer, the reflective layer comprising reflective flakes in a transparent binder, wherein the microspheres are partially embedded in at least one of the color layer and the reflective layer, the reflective flakes being small enough relative to the microspheres that individual microspheres have the reflective flakes arranged in cup-like fashion about their embedded portions;
• and
• d) a bonding layer printed over the color layer and the reflective layer, the bonding layer being sufficiently thick to embed all exposed surfaces of the color layer and the reflective layer and being adapted for use in securing the sheet material to a substrate.