Gravure printing of transparent conductive films containing networks of metal nanoparticles
View Patent ↗Methods and compositions are disclosed and claimed for gravure printing of transparent conductive films comprising metal nanowires. Such films exhibiting low resistivity and superior coating uniformity may be used in electronic or optical articles.
1. A method comprising:
providing an ink comprising nanowires, said nanowires having a distribution of lengths, said distribution having a mean L m and standard deviation σ;
providing a surface and a plurality of indentations in the surface, said plurality of indentations having a density of LPI (lines/inch);
transferring the ink into the plurality of indentations; and
transferring at least a portion of the ink from the indentations to a printing medium, wherein LPI is less than about 2.5×10 4 μm lines/inch divided by L m +3σ.
2. The method according to claim 1 , wherein at least some of the nanowires have an aspect ratio greater than about 50.
3. The method according to claim 1 , wherein the ink further comprises a polymer binder.
4. The method according to claim 3 , wherein the polymer binder comprises at least one cellulosic polymer.
5. The method according to claim 3 , wherein the printing medium is moving at a speed of U (feet/min) relative to the surface, the ink has a viscosity μ (cps), and LPI is greater than about 473−67.6 ln(μ·log 10 (U)) lines per inch.
6. The method according to claim 1 , wherein the surface is an exterior surface of a rotogravure cylinder.
7. The method according to claim 1 , wherein the printing medium is a conductive film.