Electrically conductive composition, process for making an article using same
AssigneeE-B Industries, Inc.
InventorCornelius J. N. Kelly
Life of this patent
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Abstract
The method of manufacturing, composition and product described herein utilize highly electrically resistive carbon black alone or with low resistivity carbon black to form a self-limiting electrically resistive semi-conductor which presents a positive temperature co-efficient of resistance, the methods which are described providing significantly shortened anneal times, manufacturing ease and reliability.
Claims9
An electrically conductive composition having point-to-point electrical resistance that increases with increasing temperature comprising a mixture of carbon black having high dry electrical resistivity and a crystalline polymer, the carbon black being substantially uniformly dispersed in said polymer, said polymer having at least 20% crystallinity as determined by X-ray diffraction, the percentage by weight of said high electrical resistivity carbon black based upon the total weight of said mixture being at least 6%, said mixture of high dry resistivity carbon black and polymer being substantially non-conductive upon initial mixing and before annealing, the composition having been annealed at a temperature equal to or above the crystalline melting point of the polymer for a period of time sufficient to produce a substantially constant and stable room temperature electrical resistance.
An electrically conductive composition having point-to-point electrical resistance that increases with increasing temperature comprising a mixture of high dry electrical resistivity carbon black, low dry electrical resistivity carbon black, and a crystalline polymer, the carbon blacks being substantially uniformly dispersed in said polymer, said polymer having at least 20% crystallinity as determined by X-ray diffraction, the percentage by weight of said high electrical resistivity carbon black based upon the total mixture weight being at least 6%, the remainder of the total weight of the carbon blacks being low electrical resistivity carbon black in an amount providing the desired point-to-point resistance said mixture of high dry resistivity carbon black and polymer being substantially non-conductive upon initial mixing and before annealing, said composition having been annealed at a temperature equal to or above the crystalline melting point of the polymer for a period of time sufficient to produce a substantially constant and stable room temperature electrical resistance.
Dependencies are inferred from the claim text.