3m Innovative Properties Company

John E Bailey

Kenton D Budd

Stephen B Roscoe

Chikafumi Yokoyama

Matthew H Frey

Paul S Lugg

Charles J Studiner, Iii

Scott G Theirl

Toshihro Kasai

The present invention relates to transparent microspheres (i.e., beads) that impart yellow color to retroreflected light. The microsphere preferably comprise titania plus alumina, zirconia, and/or silica and iron oxide, manganese oxide, or mixtures thereof. More particularly, the present invention relates to fused microspheres that impart yellow color to retroreflected light having both transparency and mechanical properties suitable, for example, for lens elements in retroreflective articles.

Glass-ceramic microspheres that impart yellow color to retroreflected light

Transparent solid microspheres that contain titania plus alumina, zirconia, and/or silica in a total content of at least about 75% by weight, based on the total weight of the solid microspheres, wherein the total content of alumina, zirconia, and titania is greater than the content of silica.

Transparent microspheres

A low reflectivity, variable attenuation contrast enhancement filter having a total visible light reflectance of less than about 2.0% when measured with light incident to the first outer major surface. The contrast enhancement filter has a first layer(s) for providing antireflection, the first layer(s) defining the first outer major surface; a variable attenuation element interposed between the first major outer surface and the second major outer surface; element(s) for providing fixed attenuation interposed between the variable attenuation element and the first major outer surface; and at least one substrate.

Low reflectivity contrast enhancement filter

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Shorewood, WI, United States of America

John E Bailey