Method of forming conductive films with micro-wires
A pattern of conductive micro-wires as in a conductive pattern can be prepared using photo-lithography, or imprint technology. A photocurable composition is cured to form a pattern of photocured micro-channels. A conductive composition comprising metal nano-particles is added to the photocured micro-channels and excess conductive composition outside the photocured micro-channels is removed. The conductive composition in the photocured micro-channels is then dried at a temperature of less than 60° C. The dried conductive composition in the photocured micro-channels is treated with hydrogen chloride vapor to form conductive micro-wires in the photocured micro-channels at a temperature of less than 60° C. The outer surface of the conductive micro-wires is then polished in the presence of water, to form a micro-wire pattern.
1. A method of making a micro-wire pattern in an article, the method comprising:
providing a photocurable article comprising a photocurable composition on a transparent substrate,
forming a pattern of micro-channels within the photocurable composition,
exposing the photocurable composition to curing radiation to form cured photocurable composition and photocured micro-channels within the cured photocurable composition on the transparent substrate,
applying a conductive composition comprising metal nano-particles to the photocured micro-channels,
removing any excess conductive composition outside the photocured micro-channels while leaving conductive composition within the photocured micro-channels,
drying the conductive composition in the photocured micro-channels at a temperature of less than 60° C. to provide a dried conductive composition as conductive micro-wires in the photocured micro-channels,
exposing the dried conductive composition in the photocured micro-channels to hydrogen chloride at a temperature of less than 60° C. to enhance the conductivity of the conductive micro-wires in the photocured micro-channels, and
polishing the outer surface of the cured photocurable composition in the presence of water, to form a micro-wire pattern on the transparent substrate.
2. The method of claim 1 , further comprising heating the micro-wire pattern at a temperature greater than or equal to 60° C.
3. The method of claim 1 , further comprising treating the micro-wire pattern to an environment having a humidity greater than 60%.
4. The method of claim 3 , comprising treating the micro-wire pattern to the humid environment for at least four hours.
5. The method of claim 1 , comprising exposing the dried conductive composition to the hydrogen chloride vapor for at least three seconds and up to and including 10 minutes.
6. The method of claim 1 , comprising removing any excess conductive composition using mechanically means.
7. The method of claim 1 , wherein the curing radiation is ultraviolet radiation.
8. The method of claim 1 , wherein the photocurable composition comprises a crosslinkable material.
9. The method of claim 1 , wherein the conductive composition comprises silver nano-particles.
10. The method of claim 1 , wherein the transparent substrate comprises a flexible polymeric material.
11. The method of claim 1 , wherein the photocured micro-channels have an average aspect ratio (width to depth) greater than 0.1 and up to and including 10, and an average width of at least 0.5 μm and up to and including 5 μm.
12. The method of claim 1 , wherein the conductive composition comprises silver nano-particles in an amount greater than or equal to 10 weight % of the total conductive composition solids.
13. An article comprising a transparent substrate and a micro-wire pattern prepared according to the method of claim 1 .
14. The article of claim 13 that exhibits a haze of less than 10% and a light transmission of at least 80%.