Conductive coatings and foams for anti-static protection, energy absorption, and electromagnetic compatability

Abstract

Improved compositions are disclosed which are useful in providing a conductive layer of coating on a surface to provide protection against harmful electrostatic discharges. Also disclosed are compositions useful in absorbing and dissipating mechanical and electromagnetic energy and preventing electrostatic build-up; these compositions also provide electromagnetic compatability. The compositions contain elemental carbon and a polymeric matrix or binder. The improvement comprises employing a unique ground calcined, coal-based coke which approaches graphite in terms of its performance as a conductive additive or pigment but which does not possess the disadvantages associated with the use of graphite. The unique coke employed in the compositions and methods of the present invention has a level of graphitic structure which approaches that of a true graphite. This level of graphitization can be most easily recognized by utilizing x-ray powder diffraction. More specifically, when the value of E.sub.c or the inverse carbon peak width (the 002 peak) is measured for this material using Mo K.sub..alpha. radiation (.lambda.=0.71 .ANG.), the value is in the range of about 27 to about 80, and preferably about 28 to about 75. The final compositions employ a polymer resin or matrix system as a binder. The invention also relates to the method of applying the compositions to protect the article and reinforce the substrate, and the resulting coated articles, particularly containers for shipping and storage of electronic components and magnetic information-storage materials. The conductive coating may also add strength to the containers. The compositions may also be used to absorb both mechanical and electromagnetic energy thus providing EMC, and dissipate static electricity, thus preventing electrical static build-up.

Dependencies are inferred from the claim text.