Patent GB-975749-A (GB)
Title: Improvements in the application of electrically-conductive coatings to glass fibres
IPC: H01B13/00
Filed: 1962-02-09
Abstract: Glass fibres are coated with a liquid composition containing electrically conductive particles, e.g. graphite and carbon black, and are then led into pressure contact with a heated surface and maintained in contact for a sufficient time to bond the particles to the fibres.  The fibres may be passed through a colloidal dispersion of graphite particles in water to form a coating of the particles on the fibres and then heated by pressure contact with a hot surface to cause the particles to adhere to the fibres and the fibres to adhere to one another.  Prior to coating with the electrically conductive particles the fibres may be coated with 0.5-15% by weight of a carbonizable or caramelizable material, e.g. a starch, a sugar such as glucose, sorbitol, glycerol or polyvinyl acetate, the heat treatment after application of the coating of electrically conductive particles serving to carbonize or caramelize the material and cause the particles to adhere to the fibres.  As shown in Fig. 1, glass fibre strands 14 may be passed from creel 10 through the guide openings in guide structure 26 and central eyes 28 where they are formed into rovings, over roller 32 which dips into water, which may contain 2-5% by weight of an alcohol, e.g. ethyl alcohol, in pan 36, and through pan 38 which contains the particles of electrically-conductive material. The coated rovings then pass through openings of predetermined size in dies 58 to <PICT:0975749/C1/1> wipe off excess particles and fluid to maintain a uniform coating thickness and under a heated idler roller 60 and are then placed in pressure contact with a rotating drum 62 heated to a temperature up to 850 DEG  F. to flatten the bundle of filaments into substantially parallel alignment and bond the conductive particles to the filaments and the filaments to one another prior to winding on take-up rollers 64.  Several coatings of electrically-conductive particles may be applied.  The electrical properties of the coated glass fibres may be improved by passing an electric current through them as they are heated to carbonize and bake the coating thereon.ALSO:Glass fibres are coated with a liquid composition containing electrically conductive particles of a metal or an organo metallic compound which decomposes on heating to form electrically-conductive metallic particles, and are then <PICT:0975749/C6-C7/1> led into pressure contact with a heated surface and maintained in contact for a sufficient time to bond the particles to the fibres. Prior to coating with the electrically conductive particles the fibres may be coated with 0.5-15% by weight of a carbonizable or caramelizable material, e.g. a starch, a sugar such as glucose, sorbitol, glycerol or polyvinyl acetate, the heat treatment after application of the coating of electrically conductive particles serving to carbonize or caramelize the material and cause the particles to adhere to the fibres.  As shown in Fig. 1, glass fibre strands 14 may be passed from creel 10 through the guide openings in guide structure 26 and central eyes 28 where they are formed into rovings, over roller 32 which dips into water, which may contain 2-5% by weight of an alcohol, e.g. ethyl alcohol, in pan 36, and through pan 38 which contains the particles of electrically-conductive material. The coated rovings then pass through openings of predetermined size in dies 58 to wipe off excess particles and fluid to maintain a uniform coated thickness and under a heated idler roller 60 and are then placed in pressure contact with a rotating drum 62 heated to a temperature up to 850  DEG F. to flatten the bundle of filaments into substantially parallel alignment and bond the conductive particles to the filaments and the filaments to one another prior to winding on take-up rollers 64.  Several coatings of electrically-conductive particles may be applied.  The organo metallic compound may be an organic salt or alkyl compound of nickel, iron or zinc. The electrical properties of the coated glass fibres may be improved by passing an electric current through them as they are heated to carbonize and bake the coating thereon.