Plastic article containing electrically conductive fibers

A plastic grain having a length between about 0.4 cm and 1.2 cm including a pure plastic and a low molecular weight plastic material and electrically conductive fibers which have been subjected to shear forces so that they are dispersed therein, whereby the conductive fiber content therein has a concentration of said conductive fibers that ranges from about 0.5% to about 2.0%.

A thread comprising a bundle of between 1000 and 35000 adjacent conductive fibers embedded in plastic, wherein the fiber content therein is between about 30 volume percent and about 70 volume percent, the fiber conductivity is at least 0.5% of the copper standard, the fiber diameter is a most 0.015 mm and the plastic includes a thermoplastic polymer of relatively low molecular weight.

A plastic composite article in the form of a plate or sheet comprised of a plastic material in which the volume concentration (C%) of electrically conductive fibers varies from about 0.03 to about 0.5%, said conductive fibers have an effective diameter (D) ranging from about 0.002 mm to about 0.015 mm and an average length (L) varying from about 0.5 mm to about 5.0 mm with a resulting D/L ratio ranging from about 0.0005 to about 0.008 for a major part of the fibers and which are substantially uniformly distributed throughout the composite article so that the article has a predetermined level of conductivity so that the resistance of the composite article is less than about 3.1 ohm-cm wherein the conductive fibers have a specific conductivity of at least 0.5% of the copper standard.

A plastic plate or sheet formed from a plastic material having a predetermined portions through which conductive fibers are substantially uniformly distributed, said conductive fibers being present in said predetermined portions at a concentration (C %) ranging between about 0.05% to about 0.5% volume, with a major part of the individual fibers in said predetermined portions having a D/L ratio which varies from about 0.0005 to about 0.008 so that in said predetermined portions the resistance of the plate or sheet is less than about 3.1 ohm-cm wherein the conductive fibers have a specific conductivity of at least 0.5% of the copper standard.

A process for forming plastic articles having at least predetermined electrically conductive portions therein including the steps of

• admixing a predetermined volume of substantially pure plastic material with another predetermined volume of fiber/plastic composite granules, said granules being comprised of at least a plastic material with a relatively low molecular weight which is compatible with said pure plastic material and conductive fibers, embedded in the low molecular weight material, having a substantially parallel fiber arrangement within the granule, said granule being sheathed with an additional plastic material and having between 1000 and 35000 conductive fibers in a bundled arrangement with a fiber diameter of less than about 0.015 mm,
• heating the admixture and working the heated admixture while maintaining a low shear conditions to avoid excessive breakage of the fibers, but with sufficient shear to substantially evenly disperse the fibers within the heated admixture,
• forwarding the hot worked admixture through at least one orifice and forming it to a certain shape and cooling the thus shaped admixture.

A process for forming plastic articles having at least predetermined electrically conductive portions therein including the steps of

• admixing a predetermined volume of substantially pure plastic material with another predetermined volume of fiber/plastic composite granules, said granules, being comprised of at least a plastic material with a relatively low molecular weight which is compatible with said pure plastic material and conductive fibers having a substantially parallel fiber arrangement within the granule,
• heating the admixture and working the heated admixture while maintaining low shear conditions to avoid excessive breakage of the fibers, but with sufficient shear to substantially evenly disperse the fibers within the heated admixture,
• forwarding the hot worked admixture through at least one orifice and forming it to a certain shape with a conductive fiber content between about 0.5% volume and about 2% volume, cooling the thus shaped mixture and the further step of chopping the extruded shape into grains having a length from about 0.4 centimeters to about 1.2 centimeters.