Sol bonded colorant clusters and process for making
AssigneeMinnesota Mining and Manufacturing Company
InventorsGeoffrey P. Morris, Chester A. Bacon, Jr., Wallace K. Bingham
Life of this patent
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Abstract
Colorant clusters comprising an aggregation of a plurality of grains of sol-derived material and colorant. The clusters are particularly useful as pigments in liquid compositions, e.g., paints and inks, for forming coatings that are retroreflective immediately upon drying. Also, a process for preparing such colorant clusters comprising admixing colorant in a binder sol to yield a pigment sol and then removing liquid medium from the pigment sol to yield the clusters. Also, a coating composition comprising retroreflective elements, a vehicle, and the aforementioned colorant clusters. After application of the composition to a substrate, the resultant coating is immediately retroreflective upon drying.
Claims40
Colorant clusters, each comprising an aggregation of a plurality of grains of sol-derived material and colorant, wherein the average diameter of said clusters is up to about 200 microns and said grains have an average diameter of about 360 nanometers or less.
A coating composition for providing retroreflective coatings, said composition comprising:
- a) retroreflective elements;
- b) a coating vehicle;
- and
- c) a plurality of colorant clusters, said colorant clusters each comprising an aggregation of a plurality of grains of sol-derived material and colorant, wherein the average diameter of said clusters is up to about 200 microns and said grains have an average diameter of about 360 nanometers or less.
A process for manufacturing colorant clusters comprising:
- a) providing a binder sol comprising a suspension of colloidal particles in a liquid medium, wherein the colloidal particles have an average diameter of about 360 nonometers or less;
- b) admixing colorant with said binder sol to yield a pigment sol;
- and
- c) removing said liquid;
- to yield colorant clusters which each comprise an aggregation of a plurality of grains of sol-derived material and colorant, wherein the average diameter of said clusters is up to about 200 microns.
Dependencies are inferred from the claim text.