Static dissipative textile and method for producing the same

Abstract

The present invention relates generally to a static dissipative textile having an electrically conductive surface achieved by coating the textile with an electrically conductive coating in a variety of patterns. The electrically conductive coating is comprised of a conducting agent and a binding agent, and optionally a dispersing agent and/or a thickening agent. The static dissipative textile generally comprises a fabric which may be screen printed or otherwise coated with a conductive coating on the backside of the fabric so that the conductive coating does not interfere with the appearance of the face of the fabric. The economically produced fabric exhibits relatively permanent static dissipation properties and conducts electric charge at virtually any humidity, while the conductive coating does not detrimentally affect the overall appearance or tactile properties of the fabric. Also encompassed within this invention is a method for producing a static dissipative textile having an electrically conductive surface.

We claim:  
     
         1 . A method for providing a static dissipative textile comprising a fabric having an electrically conductive surface, the method comprising the steps of: 
 (a) providing a knitted, woven, or nonwoven fabric having a first surface;    (b) applying an electrically conductive coating to the first surface of the fabric in a pattern comprised of a plurality of lines to provide a static dissipative textile, wherein the lines have a line width of between about 0.01 and about 0.5 inches, and wherein the electrically conductive coating is comprised of a conducting agent and a binding agent; and    (c) drying the static dissipative textile.    
     
     
         2 . The method of  claim 1 , wherein the lines have a line width of between about 0.03 and about 0.2 inches.  
     
     
         3 . The method of  claim 1 , wherein the step of drying the static dissipative textile includes drying the static dissipative textile for between about 30 seconds and about 5 minutes at a temperature of between about 250 and about 375 degrees F.  
     
     
         4 . The method of  claim 1 , further including the step of curing the static dissipative textile after the step of drying the static dissipative textile.  
     
     
         5 . The method of  claim 1 , further including the step of exposing the static dissipative textile to one or more chemical or mechanical finishing processes after the step of drying the static dissipative textile.  
     
     
         6 . The method of  claim 1 , wherein the electrically conductive coating is applied to the first surface of the fabric by screen printing, transfer printing, lithographic printing, ink jet printing, digital printing, or combinations thereof.  
     
     
         7 . The method of  claim 6 , wherein the electrically conductive coating is applied to the first surface of the fabric by screen printing.  
     
     
         8 . The method of  claim 1 , wherein the pattern of the electrically conductive coating forms at least one intersection of the lines.  
     
     
         9 . The method of  claim 1 , wherein the pattern of the electrically conductive coating forms a plurality of intersections of the lines.  
     
     
         10 . The method of  claim 9 , wherein the pattern of the electrically conductive coating forms connected letters.  
     
     
         11 . The method of  claim 10 , wherein the pattern of the electrically conductive coating forms connected words.  
     
     
         12 . The method of  claim 9 , wherein the pattern of the electrically conductive coating forms a grid pattern.  
     
     
         13 . The method of  claim 12 , wherein the pattern of the electrically conductive coating forms a diagonal grid pattern.  
     
     
         14 . The method of  claim 12 , wherein the grid pattern of the electrically conductive coating is characterized by a spacing between the lines of about 0.2 and about 10 inches.  
     
     
         15 . The method of  claim 12 , wherein the grid pattern of the electrically conductive coating is characterized by a spacing between the lines of about 0.5 and about 2 inches.  
     
     
         16 . The method of  claim 1 , wherein the electrically conductive coating is applied to a second surface of the fabric.  
     
     
         17 . The method of  claim 1 , wherein the conducting agent of the electrically conductive coating comprises a material selected from the group consisting of graphite; carbon particles; intrinsically conductive polymers; metal; metal oxides; metal shavings; fibers or beads coated with graphite, carbon particles, intrinsically conductive polymers, metal, metal oxides, or metal shavings; and combinations thereof.  
     
     
         18 . The method of  claim 17 , wherein the conducting agent comprises conducting particles selected from the group consisting of spheres, rods, flakes, and combinations thereof.  
     
     
         19 . The method of  claim 18 , wherein the conducting particles are characterized by a size of between about 0.1 and about 100 microns.  
     
     
         20 . The method of  claim 18 , wherein the conducting particles are characterized by a size of between about 1 and about 5 microns.  
     
     
         21 . The method of  claim 18 , wherein the conducting agent has an aspect ratio equal to or greater than about 2.  
     
     
         22 . The method of  claim 18 , wherein the conducting agent has an aspect ratio equal to or greater than about 4.  
     
     
         23 . The method of  claim 18 , wherein the conducting agent comprises graphite having an aspect ratio of about 4, and wherein the graphite comprises about 15 volume percent of the electrically conductive coating.  
     
     
         24 . The method of  claim 1 , wherein the binding agent of the electrically conductive coating comprises a material selected from the group consisting of water-borne latexes, solvent-borne polymer systems, liquid rubbers, thermoplastic hot melts, thermoset hot melts, multi-component reactive polymers, and combinations thereof.  
     
     
         25 . The method of  claim 24 , wherein the binding agent of the electrically conductive coating comprises a material selected from the group consisting of acrylic latex, polyurethane, silicone, polyvinyl chloride latex, and combinations thereof.  
     
     
         26 . The method of  claim 24 , wherein the binding agent has an elongation at break equal to or greater than about 80 percent of the static dissipative textile's elongation at break, wherein the static dissipative textile's elongation at break is calculated in the direction having the lowest elongation at break.  
     
     
         27 . The method of  claim 24 , wherein the binding agent has a glass transition temperature equal to or less than about 0 degrees C.  
     
     
         28 . The method of  claim 24 , wherein the binding agent has a melting temperature of equal to or greater than about 100 degrees C.  
     
     
         29 . The method of  claim 1 , wherein the electrically conductive coating further comprises a dispersing agent, and wherein the dispersing agent is a non-ionic surfactant.  
     
     
         30 . The method of  claim 1 , wherein the electrically conductive coating further includes a thickening agent.  
     
     
         31 . The method of  claim 30 , wherein the thickening agent comprises an associative thickener.  
     
     
         32 . The method of  claim 31 , wherein the associative thickener is a water-soluble acrylic polymer.  
     
     
         33 . The method of  claim 30 , wherein the thickening agent is a cellulosic thickener.  
     
     
         34 . The method of  claim 1 , wherein the first surface of the fabric is coated with an electrically conductive coating in a pattern comprised of a plurality of lines, and wherein the pattern provides between about 1 percent and about 50 percent coating coverage on the first surface of the fabric.  
     
     
         35 . The method of  claim 1 , wherein the first surface of the fabric is coated with an electrically conductive coating in a pattern comprised of a plurality of lines, and wherein the pattern provides between about 5 percent and about 30 percent coating coverage on the first surface of the fabric.  
     
     
         36 . A method for providing a static dissipative textile comprising a fabric having an electrically conductive surface, the method comprising the steps of: 
 (a) providing a knitted, woven, or nonwoven fabric having a first surface;    (b) applying a water-soluble polymer to the first surface of the fabric;    (c) applying an electrically conductive coating to the first surface of the fabric in a pattern comprised of a plurality of lines to provide a static dissipative textile, wherein the electrically conductive coating is comprised of a conducting agent and a binding agent; and    (d) drying the static dissipative textile.    
     
     
         37 . The method of  claim 36 , further including the step of drying water-soluble polymer applied to the first surface of the fabric before the step of applying the electrically conductive coating.  
     
     
         38 . The method of  claim 36 , further including the step of washing the water-soluble polymer off the first surface of the fabric after the step of drying the static dissipative textile.  
     
     
         39 . A method for providing a static dissipative textile comprising a fabric having an electrically conductive surface, the method comprising the steps of: 
 (a) providing a knitted, woven, or nonwoven fabric having a first surface;    (b) applying an electrically conductive coating to the first surface of the fabric in a pattern comprised of a plurality of lines to provide a static dissipative textile, wherein the electrically conductive coating is comprised of a conducting agent and a binding agent, and wherein the lines of the pattern of the electrically conductive coating define an opening not greater than about 3 inches square on the first surface of the fabric; and    (c) drying the static dissipative textile.    
     
     
         40 . A method for providing a static dissipative textile comprising a fabric having an electrically conductive surface, the method comprising the steps of: 
 (a) providing a knitted, woven, or nonwoven fabric having a first surface;    (b) applying an electrically conductive coating to the first surface of the fabric in a pattern comprised of a plurality of lines to provide a static dissipative textile, wherein the electrically conductive coating is comprised of a conducting agent and a binding agent, wherein the conducting agent is selected from the group consisting of graphite; carbon particles; intrinsically conductive polymers; metal oxides; fibers or beads coated with graphite, carbon particles, intrinsically conductive polymers, or metal oxide; and combinations thereof, and wherein the conducting agent comprises less than about 30 volume percent of the electrically conductive coating; and    (c) drying the static dissipative textile.