Soft conductive materials

Claim 2

A soft, conformable, electrically conductive composition comprising: (a) a soft polymeric binder forming a coherent matrix and having a Shore A hardness of less than about 40, (b) a plurality of insoluble, deformable, generally non-reactive and non-conductive, tacky, spherical domains having Shore A hardness less than about 40 consisting of elastic copolymer of at least one monomer selected from the group consisting of substantially oil-insoluble, water-soluble ionic monomers and maleic anhydride and at least one alkyl acrylate monomer which, as a homopolymer, has T g below about -20° C. dispersed in said binder in an amount of from about 15 to 60 percent by volume of said composition; and (c) an electrically conductive filler dispersed in said binder interjacent said domains in an amount effective to provide at least one electrically conductive pathway through said composition.

Claim 3

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

Claim 4

The composition of claim 2 wherein said adhesive is an iso-octylacrylate-acrylamide copolymer.

Claim 5

The composition of claim 2 wherein said adhesive is an iso-octylacrylate and acrylic acid copolymer.

Claim 6

The composition of claim 2 wherein said adhesive is a polybutene.

Claim 7

The composition of claim 2 wherein said spherical domains are iso-octylacrylate-ammonium acrylate copolymer microspheres.

Claim 8

An electrically conductive sheet comprising the composition of claim 2.

Claim 9

A normally tacky and pressure-sensitive adhesive tape comprising a flexible self-supporting sheet having the composition of claim 2 adhered to one major surface thereof, the thickness of said composition being not less than about 0.054 mm.

Claim 10

The composition of claim 1 wherein said conductive filler is selected from the group consisting of finely divided carbon black, graphite, silver, nickel and copper.

Claim 11

The composition of claim 9 wherein said conductive filler is nickel particles having an average particle size of from 2 to 4 microns and is present in the composition at from about 1 to 25 percent by volume.

Claim 12

The composition of claim 9 wherein said conductive filler is silver-coated ceramic particles having an average diameter of from about 5 to 40 microns and comprises from 5 to 60 percent by volume of the composition.

Claim 13

A soft, conformable, conductive, pressure-sensitive adhesive composition comprising: (a) a soft polymeric pressure-sensitive adhesive binder forming a coherent matrix, said binder selected from the group consisting of acrylate copolymer, tackified polybutylene, tackified rubber resin and vinyl ester; (b) from about 15 to 60 percent, based on the volume of the total composition, being insoluble, deformable, generally non-reactive, and non-conductive, tacky spherical domains having Shore A hardness less than about 40 and a diameter from about 6 to 80 microns randomly dispersed in said adhesive binder, said domains consisting of about 90-99.5 percent by weight of at least one alkyl acrylate ester which as a homopolymer has T g below about -20° C. and about 10 to about 0.5 percent by weight of at least one monomer of the group consisting of substantially oil-insoluble, water-soluble ionic monomers and maleic anhydride; and (c) from about 1 to 60 percent of the total composition by volume being electrically conductive particles having particle size less than 100 microns and less than the diameter of said domains dispersed in said adhesive binder interjacent said domains; wherein said particles form electrically conductive pathways through said composition, said domains imparting conformability to said composition.

Claim 14

A soft, conformable, conductive, pressure-sensitive adhesive composition comprising: (a) a soft polymeric pressure-sensitive adhesive binder forming a coherent matrix, said binder selected from the group consisting of acrylate copolymer, tackified polybutylene, tackified rubber resin and vinyl ester; (b) from about 15 to 60 percent, based on the volume of the total composition, being insoluble, deformable, generally non-reactive, and non-conductive, tacky spherical domains having Shore A hardness less than about 40 and a diameter from about 6 to 80 microns randomly dispersed in said adhesive binder, said domains consisting of about 90-99.5 percent by weight of at least one alkyl acrylate ester which as a homopolymer has T g below about -20° C. and about 10 to about 0.5 percent by weight of at least one monomer of the group consisting of substantially oil-insoluble, water-soluble ionic monomers and maleic anhydride; and (c) from about 1 to 60 percent of the total composition by volume being electrically conductive particles having particle size less than 100 microns and less than the diameter of said domains dispersed in said adhesive binder interjacent said domains; wherein said particles form electrically conductive pathways through said composition, said domains imparting conformability to said composition.