Aqueous printable electrical conductors

Abstract

An aqueous printable electrical conductor (APEC) is defined as a dispersion comprising metal powder (with specific surface properties) dispersed into an aqueous acrylic, styrene / acrylic, urethane / acrylic, natural polymers vehicle (gelatine, soy protein, casein, starch or similar) or in a film forming reactive fatty acids mixture without a binder resin. The aqueous printable dispersion can be applied to substrates through different printing processes such as flexography, gravure, screen, dry offset or others. Exemplary substrates include: (1) coated paper, (2) uncoated paper, and (3) a variety of plastics with treated and untreated surfaces. When printed at a thickness of 1-8 [mu]m, heating to cure is not required as the dispersion cures at ambient temperatures. When the dispersion is used for any of the above applications it will provide sufficient electrical conductivity to produce electrical circuits for intelligent and active packaging, sensors, radio frequency identification (RFID) tag antennae, and other electronic applications.

Description

field of invention

[0001]

[001] The present invention relates to the preparation of electrical conductors that can be printed on substrates and used as circuits in, for example, intelligent and active packaging, sensors and RFID antennas. These electrical conductors are referred to herein as aqueous printable electrical conductors or "APECs". Background of the invention

[0002]

[002] Printable inks that can be used in different applications are known, for example, in US Patent No. 6,379,745 and in US Patent Application No. 2003 / 0151028. However, these inks have limitations. The printable conductive material of the '745 patent is non-aqueous, and substrates for use with such inks are generally limited to plastics, which are heat resistant and not recyclable. The materials of the '028 patent application do not conduct to the desired degree for the applications described herein, and they are not printable on plastic. Furthermore, neither document describes how the use of an...