Electrically Conductive Glass Yarn and Constructions Including Same

Abstract

The invention relates to glass strands and glass strand structures coated with an electrically conducting coating composition which comprises (as % by weight of solid matter): 6 to 50% of a film-forming agent, preferably 6 to 45%, 5 to 40% of at least one compound chosen from plasticizing agents, surface-active agents and/or dispersing agents, 20 to 75% of electrically conducting particles, 0 to 10% of a doping agent, 0 to 10% of a thickening agent, 0 to 15% of additives. The invention also relates to the electrically conducting coating composition used to coat the said strands and strand structures, to their process of manufacture and to the composite materials including these strands or strand structures. Application to the preparation of structures and composite materials which can be heated by the Joule effect or which can be used for electromagnetic shielding.

1 . Glass strand or glass strand structure coated with an electrically conducting coating composition which comprises (as % by weight of solid matter):
 6 to 50% of a film-forming agent, preferably 6 to 45%,   5 to 40% of at least one compound chosen from plasticizing agents, surface-active agents and/or dispersing agents,   20 to 75% of electrically conducting particles,   0 to 10% of a doping agent,   0 to 10% of a thickening agent,   0 to 15% of additives.   
     
     
         2 . Strand or structure according to  claim 1 , characterized in that the film-forming agent is a polymer. 
     
     
         3 . Strand or structure according to  claim 2 , characterized in that the film-forming agent is chosen from polyvinylpyrrolidones, poly(vinyl alcohol)s, polyacrylics, styrene polymers, poly(vinyl chloride)s, polyurethanes and the blends of these polymers. 
     
     
         4 . Strand or structure according to  claim 1 , characterized in that the plasticizing, surface-active and/or dispersing agent is chosen from optionally halogenated, aliphatic or aromatic, polyalkoxylated compounds, from polyalkoxylated fatty acid esters, from amino compounds, from silica derivatives and from the blends of these compounds. 
     
     
         5 . Strand or structure according to  claim 1  characterized in that the conducting particles are based on carbon. 
     
     
         6 . Strand or structure according to  claim 5 , characterized in that the size of the particles does not exceed 250 μm. 
     
     
         7 . Strand or structure according to  claim 6 , characterized in that 30 to 60% of the particles have an aspect ratio which varies from 5 to 20. 
     
     
         8 . Strand or structure according to  claim 6 , characterized in that at least 15% of the particles have a flake or needle shape. 
     
     
         9 . Electrically conducting aqueous coating composition for a glass strand or glass strand structure, characterized in that it comprises:
 6 to 50% of a film-forming agent,   5 to 40% of at least one compound chosen from plasticizing agents, surface-active agents and/or dispersing agents,   20 to 75% of electrically conducting particles,   0 to 10% of a doping agent,   0 to 10% of a thickening agent,   0 to 15% of additives.   
     
     
         10 . Composition according to  claim 9 , characterized in that it exhibits a viscosity of greater than or equal to 190 mPa·s. 
     
     
         11 . Composition according to  claim 10 , characterized in that it comprises:
 2.5 to 45% of graphite particles having a size of between 10 and 100 μm, at least 5% by weight of these particles being provided in the form of flakes or needles with an aspect ratio of greater than or equal to 5,   0 to 45%, of graphite particles with a size of less than 10 μm,   2.5 to 45%, of carbon black particles having a size of less than 1 μm.   
     
     
         12 . Process for the preparation of a glass strand or of a glass strand structure according to  claim 1  which comprises the stages consisting in
 coating a glass strand or a glass strand structure with the conducting coating composition according to  claims 1 , and   heating the said coated strand or the said coated structure at a temperature sufficient to remove the water and to strengthen the conducting coating.   
     
     
         13 . Process according to  claim 12 , characterized in that the coating is carried out by immersion in a bath of the conducting coating composition. 
     
     
         14 . Process according to  claim 12 , characterized in that the heating is carried out at a temperature of greater than approximately 105° C. and less than approximately 220° C. 
     
     
         15 . Glass strand structure according to  claim 1 , characterized in that it is provided in the form of an assemblage of intertwined strands or nonintertwined strands. 
     
     
         16 . Structure according to  claim 15 , characterized in that it exhibits an electromagnetic shielding value of between 5 and 50 dB, preferably between 5 and 35 dB, measured between 100 MHz and 2.7 GHz. 
     
     
         17 . Composite material comprising a matrix reinforced by glass strands or a glass strand structure according to  claim 1 . 
     
     
         18 . Material according to  claim 17 , characterized in that the matrix is a thermoplastic or thermosetting polymer or a cementing material.