Preparation, characterisation and application of carbon black containing electrically conductive inks for textile printing

In comparison to weaving or other techniques that are employed to embed conductive tracks in textile fabric structure, the obvious advantages of printing the desired conductive pattern are the simplicity of the process and the suitability for low volume production runs as well as high volume production runs. However, the generally inferior durability and poorer electrical performance of conductive inks that have been printed onto a textile fabric give rise to challenges.
In this study, electrically conductive grades of carbon black pigment were used to formulate screen printing inks for use on textiles. On an equal weight basis, electrically conductive grades impart higher electrical conductivity compared to the printing ink grades of carbon black pigment. However, the conductive grades of carbon black are difficult to disperse and stabilise in aqueous media. Therefore in this study, a procedure was devised initially to prepare stable, waterborne dispersions of a number of highly conductive grades of carbon black pigment. The stability of pigment dispersions was characterised by conducting rheological, particle size and accelerated gravitational sedimentation analyses on appropriate formulations.
In order to formulate finished inks from the optimised, stable pigment dispersions, various binders were incorporated in the formulations followed by characterisation of the stability and the electrical properties of the finished inks. Films of the formulated inks were deposited onto various textile substrates. This was followed by testing of the washing and creasing performance of these ink films. It was found that the formulated inks performed considerably better than the tested commercial inks. It was shown that following the ink preparation procedure devised in this study, electrically conductive grades of carbon black pigment can be used to formulate textile printing inks which not only possess very high electrical conductivity but are also durable to withstand washing and creasing of textiles.