A Method for Making Patterned Conductive Textiles

Abstract

A method of forming a conductive/nonconductive pattern on a conductive particle-coated fabric uses chemical etching techniques to remove specific areas of conductive material from the fabric, producing non-conductive areas where the fabric was exposed to an etching agent, and leaving conductive areas where the conductive coating was protected by an etch-resistant coating.

Claims

1. A method of forming conductive and nonconductive areas on a conductive fabric, the fabric comprising non-conductive fibres coated with conductive material prior to forming the fabric, the method comprising: depositing at least one of an etch-resistant emulsion, capillary film and paste on both sides of the fabric that covers an area of the fabric desired to be conductive, removing conductive material from a non-coated area of the fabric using an etching agent, and removing at least one of the etch-resistant emulsion, capillary film and paste to reveal a conductive area.

2. The method of claim 1, wherein the conductive material comprises at least one of a conductive metal, a metal-metal alloy, a metal-inorganic mixture, a conductive inorganic material.

3. The method of claim 1, wherein removal of the conductive material from the non-coated area using the etching agent comprises chemical solution etching.

4. The method of claim 3, wherein the chemical solution etching comprises submerging the conductive coated fabric in at least one of an etchant solution, spray etching, and painting etching.

5. The method of claim 1, wherein removal of the conductive material is performed through use of at least one of an etching paste, vapor phase etching, and plasma etching.

6. The method of claim 5, wherein the etching paste comprises at least one of poly(acrylic acid), poly(ethylene glycol), poly(ethylene oxide), poly(methacrylic acid), poly(ethylenimine), poly(acrylamide), poly(styrene sulfonate), poly(vinylpyrrolidone), and dextran.

7. The method of claim 1, wherein the etching agent comprises at least one of zinc formaldehyde sulfoxylate, sodium formaldehyde sulfoxylate, thiourea dioxide, sodium hydrosulphite, sodium borohydride, hydrazine, ammonium hydroxide, and oxidization agents.

8. The method of claim 1, wherein the etching agent comprises at least one of an inorganic salt, an acidic etchant, a basic etchant, an oxidizing agent, a reducing agent, and a coordinating ligand.

9. The method of claim 8, wherein the inorganic salt comprises at least one of aluminium chloride, iron nitrate, iron chloride, iron cyanide, potassium nitrate, potassium thiosulfate, sodium nitrate, sodium chloride, and sodium chlorate.

10. The method of claim 8, wherein the acidic etchant comprises at least one of oxalic acid, nitric acid, acetic acid, formic acid, phosphoric acid, hydrochloric acid, hydrofluoric acid, and sulphuric acid.

11. The method of claim 8, wherein the basic etchant comprises at least one of ammonia, ammonium hydroxide, calcium carbonate, potassium carbonate, lithium hydroxide, and sodium hydroxide.

12. The method of claim 8, wherein the oxidizing agent comprises at least one of hydrogen peroxide, osmium tetroxide, peracetic acid, sodium dichromate, chromic acid, ammonium dichromate, potassium dichromate, nitric acid, potassium permanganate, ammonium persulfate, nitrous oxides, nitrosyl halides, cyanide, isocyanide, barium periodate, sodium perchlorate, potassium perchlorate, sodium hypochlorite, and tetrafluoromethane.

13. The method of claim 8, wherein the reducing agent comprises at least one of sodium borohydride, lithium aluminium hydride, triethylborane, lithium hydride, and triethylsilane.

14. The method of claim 8, wherein the coordinating ligand comprises at least one of thiosulfate, cyanide, fluorine, iodine, bromine, chlorine, thiocynanide, thiourea, hexafluoroacetylacetone, and hydroxyl ions.

15. The method of claim 5, wherein the etching paste is applied to the conductive fabric by at least one of screen-printing and flexographic printing.

16. The method of claim 15, wherein removal of the conductive material is performed on both sides of the fabric simultaneously.

17. The method of claim 1, wherein depositing at least one of the etch-resistant emulsion, capillary film and paste is performed through the use of at least one of an emulsion, capillary film, simultaneous duplex printing process, screen printing, and flexographic printing.

18. The method of claim 1, comprising curing at least one of the etch-resistant emulsion, capillary film and paste prior to removing the conductive material from the non-coated area of the fabric.

19. The method of claim 1, wherein at least one of the etch-resistant emulsion, capillary film and paste comprises at least one of poly(carbonate) poly(vinylidene chloride), poly(amide), poly(imide), poly(ether) poly(vinyl chloride), poly(vinyl ester), poly(ester), poly(vinylpyridene), and poly(vinylidene chloride)-poly(acrylic acid).

20. The method of claim 1, wherein at least one of the fabric and fibres are coated in the conductive material by at least one of sputter coating, carbon coating, chemical vapour deposition, vacuum deposition techniques, evaporation deposition techniques, and solution processing.

21. The method of claim 1, wherein the conductive material is silver based.

22. The method of claim 1, wherein the fibres comprise at least one of polyester, polyolefins, polyamides, ceramics, and cellulose based fibres.

23. The method of claim 1, wherein the fabric is at least one of an article of clothing and a wearable fabric.

24. A patterned textile fabric with conductive and nonconductive areas, produced by the method of claim 1.

25. The method of claim 2, wherein the conductive inorganic material comprises carbon.

26. The method of claim 7, wherein the oxidization agents comprise at least one of sodium hypochlorite and hydrogen peroxide.

Description

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0035] Specific embodiments of the invention will further be described by way of example only.

[0036] Embodiments of the present invention relate to a simple method of producing electrically conductive patterns on a textile fabric by removing conductive material from the surface of an area of conductively-coated fibres by printing a pattern of etch-resistant coating on the surface of the conductive fabric and subsequently etching away the conductive material from the exposed parts of the fabric to leave a pattern of nonconductive areas.

EXAMPLE 1

[0037] An exemplary method of forming a nonconductive pattern on a uniformly silver-coated nanoparticulate fibre fabric involves first the printing of an etch-resistant polymer mask of WPS Black Paper and Board ink, produced and supplied by Wicked Printing Stuff, onto the conductive fabric, preferably so that both sides of the fabric are coated at the same time using a duplex screen printing machine. The ink is printed in a pattern that is a positive of where the conductive areas should be on the finished material and is allowed to dry at 130 C. for 10 minutes. Next an etching solution is prepared by adding 0.1 moles of iron (III) nitrate to a litre of deionised water with stirring until all solids have dissolved. The conductive fabric is then immersed uniformly in the etching solution for 5 minutes at room temperature. The fabric is then removed from the etching solution and washed with deionised water to remove any remaining etching solution before it is allowed to dry completely. The etch-resistant polymer mask is then removed using an organic solvent wash such as WPS High Strength Screen Wash and the fabric is then left to dry at room temperature.

EXAMPLE 2

[0038] Another method of forming a non-conductive pattern on a uniformly coated silver-particle coated fibre fabric may involve first the printing of an etching paste containing an acidic etching agent, inorganic metal salt, acidic oxidant, water soluble polymer and solvent onto the conductive fabric. The etching paste is printed in a pattern that is a negative of where the conductive areas should be on the finished material and is allowed to dry at room temperature for 10 minutes. Next the printed fabric is heated for 10 minutes at 60-130 C., then the etching paste is washed off using deionised water and the patterned conductive fabric is left to dry at room temperature.

EXAMPLE 3

[0039] Yet another method of forming a nonconductive pattern on a uniformly coated conductive silver-particle coated fibre fabric may involve first applying Ulano DP9250 water resistant emulsion to the fabric and then drying the emulsion. A photopositive of the conductive pattern is then applied to the fabric and they are exposed to actinic radiation for a sufficient amount of time that the exposed areas of the emulsion have hardened. The unhardened areas are then washed out using water before the fabric is placed into an etching solution. Next an etching solution is prepared by adding 0.1 moles of iron (III) nitrate to a litre of deionised water with stirring until all solids have dissolved. The conductive fabric is then immersed uniformly in the etching solution for 5 minutes at room temperature. The fabric is then removed from the etching solution and washed with deionised water to remove any remaining etching solution before it is allowed to dry completely. The hardened emulsion mask is then removed using stencil strip solution and the fabric is then left to dry at room temperature.

Alternative Embodiments

[0040] Alternative embodiments which may be apparent to the skilled person on reading the above description may nevertheless fall within the scope of the invention, as defined by the accompanying claims.