Microspheres having a high index of refraction
Assignee3M Innovative Properties Company
InventorsMatthew H. Frey, Billy J. Frederick, Jr., Terrance L. Bescup
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Abstract
The present invention relates to microspheres (i.e., beads) having a high index of refraction. The invention also relates to retroreflective articles, and in particular pavement markings, comprising such microspheres.
Claims34
A retroreflective article comprising a binder and microspheres comprising a glass-ceramic structure where the microspheres are fused and comprise at least 60 wt-% titania, calcia, and at least one alkaline earth metal oxide other than calcia based on the total weight of the microspheres and have an index of refraction of at least 2.30.
A retroreflective element comprising a core and microspheres partially embedded in the core wherein the microspheres comprise a glass-ceramic structure where the microspheres are fused and comprise at least 60 wt-% titania, calcia, and at least one alkaline earth metal oxide other than calcia based on the total weight of the microspheres and have an index of refraction of at least 2.30.
A pavement marking comprising a binder and microspheres comprising a glass-ceramic structure where the microspheres are fused and comprise at least 60 wt-% titania, calcia, and at least one alkaline earth metal oxide other than calcia based on the total weight of the microspheres and have an index of refraction of at least 2.30.
Dependencies are inferred from the claim text.