Patent ID: 7655298

Claim:
A single layer anti-reflective hard-coat which comprises between 5 to 75 weight % of inorganic nano-particles to provide the hard-coat with a nano-structured surface having randomly distributed ridges and troughs, wherein the ridges having a height in the range of 50-200 nm and distances between ridges is less than about 400 nm, wherein the hard-coat increases an optical transmission of a substrate on which the hard-coat is formed in at least a range of wavelengths of the electromagnetic spectrum and exhibits a refractive index gradient normal to the substrate that decreases from that of the hard-coat to that of air over a spatial length scale, wherein the hard-coat has a hardness above 0.7 GPa and scratch resistance above 5 mJ μm −3 , as measured with nano-indentation on a bulk material that is used to make the hard-coat, and wherein the hard-coat is prepared by a process comprising the steps of: a) applying a mixture on a substrate, which mixture comprises i. at least a first material which does not crosslink under the conditions chosen in step b), said first material being hydroxypropyl cellulose ii. at least a second material which does crosslink under the conditions chosen in step b) iii. nano-particles, and iv. optionally at least one solvent b) inducing crosslinking in the mixture applied to the substrate, subsequently removing at least part of the first material.