Protective coating for low index material
Assignee3M Innovative Properties Company
InventorsMichael L. Steiner, William D. Coggio, Thomas J. Ludemann, Emilie L. Rexeisen, William R. Dudley, Steven J. McMan, Michael L. Ruegsegger
Life of this patent
Estimating the term…
Abstract
The present disclosure describes a protective coating for a low index material, and a process for preparing a protected low index material. The protective coating partially penetrates the pores of a low index material, providing a seal protecting the pores, and can strengthen the construction by forming a gradient in properties of the protected low index material. The present disclosure further provides a diffusing low index optical element having a protected low index material and a diffusing layer disposed on the low index material.
Claims11
A method, comprising:
- coating a first solution on a major surface of an optical element, the first solution comprising a plurality of fumed metal oxide particles, a binder, and a solvent, wherein the binder has a first concentration in the solvent;
- coating a second solution on the first solution, the second solution comprising the binder at a second concentration in the solvent, the second concentration different from the first concentration;
- and
- removing the solvent from the first solution and the second solution to form a protected film, wherein the protected film comprises:
- a low refractive index layer disposed on the major surface of the optical element, wherein the low refractive index layer comprises a plurality of interconnected voids and an effective refractive index of 1.3 or less, and
- a polymeric protective layer on the low refractive index layer, and wherein a weight ratio of the binder to the metal oxide particles increases in a thickness direction of the protected film.
Dependencies are inferred from the claim text.