Mitsubishi Rayon Co., Ltd. (Minato-Ku, Tokyo, JP) secured U.S. Patent 7,645,400 for carbon nanotube compositions and coatings that does not impair the characteristics of the carbon nanotubes and allows the carbon nanotubes to be dispersed or solubilized in a solvent.
The method does not result in separation or aggregation of the carbon nanotubes even during long-term storage. The compositions have superior electrical conductivity, film formability and moldability, and can be easily coated or covered onto a base material. The resulting coated film has superior moisture resistance, weather resistance and hardness.
In order to produce the carbon nanotube coatings, inventor Takashi Saitoh developed a carbon nanotube composition that contains a conducting polymer or heterocyclic compound trimer, a solvent and carbon nanotubes, and may additionally contain a high molecular weight compound, a basic compound, a surfactant, a silane coupling agent and colloidal silica as necessary; a composite having a coated film composed of the composition; and, their production methods.
Although the reason for this is not fully understood, the carbon nanotubes are presumed to be dispersed or solubilized together with the conducting polymer due to mutual adsorption by the conducting polymer and the carbon nanotubes due to the .pi.-.pi. interaction by .pi. electrons.
High molecular weight compounds, plastics, wood, paper, ceramics, fibers, non-woven fabrics, carbon fibers, carbon fiber paper and their films, foams, porous films, elastomers and glass plates can accept a coating of the carbon nanotube composition.
A coated film may be applied to a base material by a method used for ordinary coating. Examples of methods used include coating methods using a gravure coater, roll coater, curtain flow coater, spin coater, bar coater, reverse coater, kiss coater, fountain coater, rod coater, air doctor coater, knife coater, blade coater, cast coater or screen coater, spraying methods such as air spraying or airless spraying, and immersion methods such as dipping.
