Conformable electrically conductive compositions

Claim 2

In a comformable conductive composition comprising: (a) a soft polymeric binder forming a cohesive matrix having a Shore A hardness of less than about 40; (b) a plurality of insoluble, deformable, generally nonreactive microspheres having Shore A hardness less than about 40 dispersed in said binder in an amount from about 20 to 60 percent by weight of said composition; and (c) electrically conductive particles dispersed in said binder in an amount effective to provide at least one electrically conductive pathway through said composition; the improvement wherein said polymeric binder is polar, said microspheres are nonpolar, said conductive particles are oleophilic, and said conductive particles have an affinity for said microspheres and concentrate at the surface of said microspheres.

Claim 3

The composition according to claim 1 wherein said polymeric binder is a pressure sensitive adhesive.

Claim 4

The composition according to claim 2 wherein said polymeric binder is comprised of monomer units at least 10 percent of which contain an ionic group.

Claim 5

The composition according to claim 3 wherein said binder is poly(butylacrylate:acrylic acid) neutralized with methyldiethanolamine.

Claim 6

The composition according to claim 1 wherein said polymeric binder contains a plasticizer.

Claim 7

The composition according to claim 5 wherein said plasticizer is a polyhydric alcohol.

Claim 8

The composition according to claim 6 wherein said polyhydric alcohol is glycerol.

Claim 9

The composition according to claim 1 wherein said microspheres consist essentially of about 90 to about 99.5 percent by weight of at least one alkyl acrylate ester and about 10 to about 0.5 percent by weight of at least one monomer selected from the group consisting of substantially oil-insoluble, water soluble ionic monomers and maleic anhydride.

Claim 10

The composition according to claim 8 wherein said microspheres consist essentially of about 96 percent by weight iso-octylacrylate and about 4 percent by weight acrylamide.

Claim 11

The composition according to claim 1 wherein said conductive particles are carbon black.

Claim 12

The composition according to claim 1 wherein said conductive particles are aluminum powder treated with a keying agent to render it oleophilic.

Claim 13

In a grounding plate electrode comprising an electrically-conductive metal film having an upper surface and a lower, skin-contacting surface; means for attaching a lead wire to said metal film; a backing laminated to said upper surface; and a layer of a conformable, electrically-conductive composition on said skin-contacting surface; the improvement wherein said electrically conductive composition comprises: (a) a soft polar polymeric binder forming a cohesive matrix having a Shore A hardness of less than about 40; (b) a plurality of insoluble, deformable, generally non-reactive, non-polar microspheres having a Shore A hardness less than about 40 dispersed in said binder in an amount from about 20 to 60 percent by weight of said composition; and (3) oleophilic electrically conductive particles dispersed in said binder in an amount effective to provide at least one electrically conductive pathway through said composition, said conductive particles having an affinity for said microspheres and being concentrated at the surface of said microspheres.

Claim 14

In a grounding plate electrode comprising an electrically-conductive metal film having an upper surface and a lower, skin-contacting surface; means for attaching a lead wire to said metal film; a backing laminated to said upper surface; and a layer of a conformable, electrically-conductive composition on said skin-contacting surface; the improvement wherein said electrically conductive composition comprises: (a) a soft polar polymeric binder forming a cohesive matrix having a Shore A hardness of less than about 40; (b) a plurality of insoluble, deformable, generally non-reactive, non-polar microspheres having a Shore A hardness less than about 40 dispersed in said binder in an amount from about 20 to 60 percent by weight of said composition; and (3) oleophilic electrically conductive particles dispersed in said binder in an amount effective to provide at least one electrically conductive pathway through said composition, said conductive particles having an affinity for said microspheres and being concentrated at the surface of said microspheres.