摘要：
A transfer sheet material for forming retroreflective graphic images on a substrate, the sheet material comprising a monolayer of transparent microspheres (12); a color layer (22) printed over the microspheres in a first graphic segment of the sheet material in an imagewise pattern, the color layer comprising a colorant in a transparent resin; a reflective layer printed over the microspheres in a second graphic segment of the sheet material in an imagewise pattern, 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, individual microspheres having the reflective flakes arranged in cup-like fashion about their embedded portions; and a bonding layer (28) 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 (30). Also, a method for making such a sheet material. Also, a sheet material having the color layer and the reflective layer combined as a single layer. Also, a sheet material having a graphic segment in which a specularly reflective metal layer is deposited over the microspheres.
权利要求：
CLAIMS:
1. A 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 pattem, the color layer comprising a 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 pattem such that 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 exposed surfaces of the color layer and the reflective layer and being adapted for use in securing the sheet material to a substrate.
2. The sheet material of claim 1, further comprising a second color layer printed in the first graphic segment in an imagewise pattem, the second color layer comprising a second colorant in a second transparent resin.
3. The sheet material of claim 1 bonded to a fabric substrate.
4. The sheet material of claim 1, wherein the reflective flakes are selected from the group consisting of metal flakes, plastic flakes, metal-plated plastic flakes, and nacreous pigment particles, and wherein the reflective flakes have a thickness in the range of about 0.03 to about 0.8 microns.
5. The sheet material of claim 1, wherein the colorant comprises a transparent pigment or transparent dye. 25666
6. The sheet material of claim 1 wherein the color layer and the reflective layer at least partially overlap, the color layer being disposed between the microspheres and the reflective layer to provide a segment of the sheet material which is capable of retroreflecting the color of the color layer when the microspheres in this segment are illuminated with incident light.
7. The sheet material of claim 1 wherein the bonding layer comprises an extender resin and a heat-activatable, hot-melt adhesive powder fused into the extender resin.
8. The sheet material of claim 1, further comprising a layer of specularly reflective metal adhered to the microspheres in an imagewise pattem to form a third graphic segment.
9. A sheet material for forming retroreflective graphic images on a substrate, the sheet material comprising: a) a monolayer of transparent microspheres; b) a colored reflective layer printed over the microspheres in a first graphic segment of the sheet material in an imagewise pattem, the colored reflective layer comprising a colorant and reflective flakes in a transparent resin, wherein the microspheres are partially embedded in the colored reflective layer, the reflective flakes being small enough relative to the microspheres that individual microspheres have reflective flakes arranged in a cup-like fashion about their embedded portions; and c) a bonding layer printed over the colored reflective layer, the bonding layer being sufficiently thick to embed all exposed surfaces of the colored reflective layer and being adapted for use in securing the sheet material to a substrate.
10. The sheet material of claim 9 further comprising: d) a layer of specularly reflective metal adhered to the microspheres in a second graphic segment of the sheet material in an imagewise pattem, the bonding layer being printed over the specularly reflective metal in the second graphic segment, the bonding layer being sufficiently thick to embed all exposed surfaces of the specularly reflective metal layer.
11. The sheet material of claim 9 wherein the reflective flakes comprise aluminum metal flakes. 12. A method for making a transfer sheet material which is adapted to be used in transferring retroreflective graphic images from the sheet material to a substrate, comprising: a) providing a carrier web; b) partially embedding a monolayer of transparent microspheres onto the carrier web; c) printing onto the microspheres in a first graphic segment of the sheet material in an imagewise pattem with a colorant composition comprising a colorant and optionally metal flakes in a transparent resin and drying the colorant composition to form a color layer; d) thereafter printing onto the first and second graphic segments of the sheet material with a bonding composition to a depth sufficient to embed exposed surfaces of the color layer and drying the bonding composition to form a bonding layer; with the proviso that if the first graphic segment does not contain metal flakes which form hemispherical reflectors beneath the embedded portions of the microspheres that step e) be performed and that it be performed before step d); wherein step e) comprises: e) printing onto the microspheres in a second graphic segment of the sheet material a reflective layer composition in an imagewise pattem such that overlapping areas of the first and second graphic segments are characterized by the color layer being disposed between the microspheres and the reflective layer composition, the reflective layer composition comprising reflective flakes in a transparent binder, and drying the reflective layer composition to form a reflective layer, 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.
13. The method of claim 12, further comprising printing onto the microspheres a second colorant composition comprising a second colorant in a second transparent resin and drying the second colorant composition to form a second color layer.
14. The method of claim 12, further comprising applying a layer of specularly reflective metal on the exposed surfaces of the microspheres.