Conductive materials
View Patent ↗A material for producing a conductive composition comprising polymer particles, conductive particles, and a liquid medium. The material is in a liquid/dispersion form until it is cured at which time it forms an electrically conductive composition. The composition contains larger sized polymer particles along with smaller metal conductive filler particles such as nanoparticle-sized filler particles. The larger polymer particles create excluded volume in the material matrix and reduce the percolation threshold of the conductive filler particles to provide a conductive material with a reduced volume fraction of electrically conductive filler. The electrical conductivity of the material is further increased after heat treatment which causes the conductive filler particles to sinter together to form a highly conductive network.
1. A curable composition consisting essentially of an aqueous polymer emulsion or a polymer particle dispersion in organic solvent, electrically conductive filler of silver or silver coated particles, and a liquid medium, wherein the average polymer particle size is larger than the average electrically conductive filler particle size wherein the size ratio between the polymer particle size and silver or silver coated particle size is about 1.5:1 to about 23:1.
2. The curable composition of claim 1 , wherein the polymer particles are selected from the group consisting of polyvinyl acetate, ethylene vinyl acetate copolymers, styrene, styrene acrylate copolymers, polyurethane, rubber latexes, natural rubber, butyl rubber, styrene butadiene rubber, and copolymers and mixtures thereof.
3. The curable composition of claim 1 , wherein the average size of the electrically conductive filler particles is in the range of about 5 nm to about 5 μm.
4. The curable composition of claim 3 , wherein the electrically conductive particles have an average size of less than about 500 nm.
5. An electrically conductive material formed from the curable composition of claim 1 .
6. An electrically conductive network structure formed from the composition of claim 1 .
7. An electronic device comprising the electrically conductive composition of claim 1 .
8. A transparent conductive material formed according to claim 1 .