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US 2012/0236413 A1Published application
Pavement markings, reflective elements, and methods of making microspheres
Assignee3M Innovative Properties Company
InventorsKenton D. Budd, Matthew H. Frey, Craig W. Lindsay
Life of this patent
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Abstract
Presently described are retroreflective articles, such as pavement markings, that comprise transparent microspheres partially embedded in a binder (e.g., polymeric). Also described are microspheres (e.g., glass-ceramic), methods of making microspheres, as well as compositions of glass materials and compositions of glass-ceramic materials. The microspheres generally comprise lanthanide series oxide(s), titanium oxide (TiO2), and optionally zirconium oxide (ZrO2)
Claims24
Microspheres, comprising one of:
- (a) at least 45 wt-% TiO2;
- at least about 0.5 wt-% and less than about 10 wt-% of one or more metal oxides selected from oxides of the lanthanide series elements;
- and
- between about 0.5 wt-% and about 25 wt-% of a combination of at least two alkaline earth oxides including selected from a group consisting of barium oxide, strontium oxide, and magnesium oxide;
- and
- (b) at least 45 wt-% TiO2;
- at least about 0.5 wt-% and less than about 10 wt-% of one or more metal oxides selected from oxides of the lanthanide series elements;
- and
- between about 0.5 wt-% and about 30 wt-% of barium oxide;
- wherein the microspheres have a refractive index of at least 2.3.
7 more elements
Microspheres, comprising:
- about 1 mol-% to about 6 mol-% of one or more oxides selected from the oxides of the lanthanide series of elements;
- about 5 mol-% to about 15 mol-% zirconia;
- about 2 mol-% to about 20 mol-% total of two or more alkaline earth oxides selected from the group of barium oxide, strontium oxide, and magnesium oxide;
- and
- about 70 mol-% to about 80 mol-% titania.
2 more elements
A retroreflective article, comprising:
- a binder;
- and
- fused, transparent microspheres having a glass-ceramic structure comprising one of:
- (a) at least 45 wt-% TiO2;
- at least about 0.5 wt-% and less than about 10 wt-% of one or more metal oxides selected from oxides of the lanthanide series elements;
- and
- between about 0.5 wt-% and about 25 wt-% of a combination of alkaline earth oxides including more than one alkaline earth oxide selected from a group consisting of barium, strontium, and magnesium;
- and
- (b) at least 45 wt-% TiO2;
- at least about 0.5 wt-% and less than about 10 wt-% of one or more metal oxides selected from oxides of the lanthanide series elements;
- and
- between about 0.5 wt-% and about 30 wt-% of barium oxide;
- wherein the microspheres have a refractive index of at least 2.3.
10 more elements
Dependencies are inferred from the claim text.