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US 5,774,265 AGranted
Durable retroreflective elements
AssigneeMinnesota Mining and Manufacturing Company
InventorsJames P. Mathers, Chris J. Goodbrake, Kathleen A. Hachey, Thomas P. Hedblom, Kathleen M. Humpal, Roger W. Lange, David C. May, Kyung H. Moh, Thomas E. Forester
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Abstract
All-ceramic retroreflective elements which may be used in pavement markings comprising an opacified ceramic core and ceramic optical elements partially embedded into the core.
Claims25
A retroreflective element comprising ceramic optical elements partially embedded in an opacified ceramic core.
A method of manufacturing a retroreflective element comprising ceramic optical elements partially embedded in an opacified ceramic core comprising the steps of:
- a) preparing a plastically deformable paste from a powdered opacified glass frit, water, and a water soluble polymer;
- b) forming the paste into a core of desired shape;
- c) heating the core to remove volatiles;
- and
- d) burying the core in a static bed of optical elements and heating it to a temperature suitable for optical element embedding.
2 more elements
Dependencies are inferred from the claim text.