The present invention relates to an abrasion-resistant electrically conductive material, more particularly a natural fibre coated with an electrically conductive conjugated polymer coating, and to a process for producing same.

Background of the Invention

Electrically conductive fabrics are useful for producing antistatic products such as clothing and floor coverings, electrically heated clothes/pads, sensor devices, computer components, microwave and electromagnetic shielding and conductive clothes for use in clean rooms for semiconductor manufacturing and packing.

It is suggested in the prior art that a conductive fabric may be produced by immersing a fabric in a solution comprising an oxidising agent and substituted or unsubstituted pyrrole or aniline, such that the fabric is coated in conductive polypyrrole or polyaniline. While this method of coating fabrics may be suitable for synthetic fabrics, fabrics containing natural fibres consistently have poor abrasion fastness and are always black in colour.

In other prior art disclosures, various synthetic fabrics had dispersed dyes applied to them and were then coated with polypyrrole or polyaniline. Such fabrics retained their colour and were suitably abrasion resistant. However, such techniques are not suitable for application to fabrics comprising natural fibres as the dyes have low affinity for natural fibres, and thus do not produce colours of high chromaticity and have low wash and rub fastness.

Accordingly, it is an object of the present invention to overcome, or at least alleviate, one or more of the difficulties or deficiencies relating to the prior art.

Summary of the Invention

In a first aspect, the present invention provides an abrasion-resistant, electrically conductive material comprising: a natural fibre-containing substrate; and an electrically conductive conjugated polymer coating thereon. In a second aspect of the present invention, there is provided a coloured, abrasion- resistant electrically conductive material comprising:

a natural fibre-containing substrate; and an electrically conductive conjugated polymer coating thereon. In the second aspect, the electrically conductive conjugated coating may be at least semi-transparent. The natural fibre-containing substrate may be of any suitable type. The natural fibre-containing substrate may be a fibre, yarns, filaments, textiles, fabrics, garments, tops and the like.

The natural fibre may be of vegetable (e.g. cotton) or animal origin. The natural fibre may be an animal fibre, e.g. wool, mohair, alpaca, or the like, or mixtures thereof, and mixtures with other natural, synthetic or regenerative fibres.

The natural fibre-containing substrate may be a wool-containing fibre, yarn, textile or fabric.

The electrically conductive conjugated polymer may be formed from a polypyrrole, polythiophene, polyaniline or like polymers, or mixtures thereof. In one embodiment, the electrically conductive conjugated polymer coating is formed from a polypyrrole.

In a third aspect of the present invention, there is provided a process for preparing an abrasion-resistant, electrically conductive material, said process comprising: providing at least one monomer capable of forming an electrically conductive conjugated polymer; and a suitable substrate having a substrate surface; subjecting the substrate surface to a surface treatment step to improve abrasion resistance; and exposing the substrate surface to a vapour of the monomer to form an electrically conductive conjugated polymer coating thereon.

In a fourth aspect of the present invention, there is provided a process for preparing an abrasion-resistant, electrically conductive material, said process comprising: providing at least one monomer capable of forming an electrically conductive conjugated polymer; and a suitable substrate having a substrate surface;

subjecting the substrate surface to a surface treatment step to improve abrasion resistance, selectively applying to the substrate surface a quenching composition to produce a predetermined pattern on the substrate surface; and exposing the substrate surface to a vapour of the monomer to form an electrically conductive conjugated polymer coating thereon.

The substrate may be a natural fibre-containing substrate.

The natural fibre-containing substrate may be a wool-containing fibre, yarn, textile or fabric.

The at least one monomer may be a substituted or unsubstituted pyrrole, a substituted or unsubstituted thiophene, or a substituted or unsubstituted aniline, or a mixture thereof.

The monomer may be selected from the group consisting of: pyrrole and 3-alkyl substituted pyrrole, and mixtures thereof.

The monomer may be 3,4-ethylenedioxythiophene. The surface treatment step may comprise subjecting the substrate to an oxidant treatment step.

The oxidant treatment step may comprise immersing the substrate in a solution comprising the oxidant.

The oxidant may be selected from one or more of the group consisting of: iron chloride, iron nitrate, antimony chloride, silver nitrate and copper chloride. In one embodiment, the oxidant is ferric chloride.

The ferric chloride concentration may be in the range of approximately 0.5mg/ml to 50 mg/ml.

The oxidant treatment step may further comprise: removing any excess oxidant solution, such that a uniform oxidant to substrate ratio is obtained.

The oxidant treatment step may further comprise the step of drying the substrate after the oxidant is applied.

The quenching composition may comprise a quenching agent selected from the group consisting of: a high polarity organic solvent and a strong organic base. The quenching composition may include a thickener component. The thickener component may be a water-based thickener.

The natural fibre-containing substrate may be a dyed material. An anionic or fluorescent dye may be applied to the material prior to processing. The conductivity and intensity of the coated substrate may be controlled by varying the concentration of the fluorescent dye. An anionic dye such as Lanasol, Lanaset or Solar dyes, for example Lanasol Yellow 4G, Lanasol Red 6G, Lanasol Blue 35G, may be used. Alternatively, a fluorescent dye, for example a conductive fluorescent dye, such as Rhodamine B, may be used. Rhodamine B has the structural formula specified below.

Definitions The following are some definitions that may be helpful in understanding the description of the present invention. These are intended as general definitions and should in no way limit the scope of the present invention to those terms alone, but are put forth for a better understanding of the following description.

Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated step or element or integer or group of steps or elements or integers, but not the exclusion of any other step or element or integer or group of elements or integers. Thus, in the context of this specification, the term "comprising" means "including principally, but not necessarily solely". The term "polythiophene" as used herein, includes within its meaning polymers and copolymers including a saturated or unsaturated thiophene or substituted thiophene repeating unit.

The term "substituted thiophene" as used herein, includes within its meaning a thiophene bearing a substituent. The substituent may be located at the 3- and/or 4- position(s) or may be a substituent bridging the 3- and 4- positions.

The term "polypyrrole" as used herein includes within its meaning polymers and copolymers including a saturated or unsaturated pyrrole or substituted pyrrole repeating unit.

The term "substituted pyrrole" as used herein includes within its meaning a pyrrole bearing a substituent or having a dopant associated therewith. The substituent may be located at the 3-ρosition.

The term "polyaniline" as used herein includes within its meaning polymers and copolymers including a saturated or unsaturated aniline or substituted aniline repeating unit. The term "substituted aniline" as used herein includes within its meaning an aniline bearing a substituent or having a dopant associated therewith.

The term "oxidant solution" as used herein, means that the oxidant is dissolved in a solvent. The solvent used is a chemical in which the oxidant is miscible.

The term "solvent" as used herein, means the chemical used to dissolve the oxidant, The term includes solvents such as: ethanol, methanol, acetone and butanone.

As used herein, the term "alkyl group" or "alkyl groups" includes within its meaning straight chain or branched chain saturated aliphatic hydrocarbons having from 1 to 25 carbon atoms, eg, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25 carbon atoms. For example, the term alkyl includes, but is not limited to, methyl, ethyl, 1 -propyl, isopropyl, 1 -butyl, 2-butyl, isobutyl, tert-butyl, amyl, 1 ,2-dimethylρropyl, 1,1-dimethylpropyl, pentyl, isopentyl, hexyl, 4-methylpentyl, 1- methylpentyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,2- dimethylbutyl, 1,3-dimethylbutyl, 1,2,2-trimethylpropyl, 1,1,2-trimethylpropyl, 2- ethylpentyl, 3-ethylpentyl, heptyl, 1-methylhexyl, 2,2-dimethylρentyl, 3,3- dimethylpentyl, 4,4-dimethylpentyl, 1,2-dimethylpentyl, 1,3-dimethylpentyl, 1,4- dimethylpentyl, 1,2,3-trimethylbutyl, 1,1,2-trimethylbutyl, 1,1,3-trimethylbutyl, 5- methylheptyl, 1 -methylheptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl and the like.

Brief description of the drawings A preferred form of the present invention will now be described by way of examples with reference to the accompanying drawings wherein:

Figure 1 is a step wise flow drawing of the batchwise vapour-phase coating process.

Figure 2 is a flow diagram illustrating the process for preparing a conducting polymer pattern on a wool textile substrate.

Figure 3 illustrates conducting polymer patterns which may be achieved (both positive and negative) utilising the process illustrated in Figure 2. Figure 4 is a graph of intensity of fluorescence (a.u.) vs wavelength (ran), for the fluorescent dyed electrically conductive polymer of Example 7.

Detailed description of the preferred embodiments

The present invention is directed to an abrasion-resistant, electrically conductive material comprising a natural fibre-containing substrate and an electrically conductive conjugated polymer coating thereon.

It has surprisingly been found that an electrically conductive material may be produced utilising a natural fibre-containing substrate, e.g. wool, which is abrasion- resistant. It has further surprisingly been found that the electrically conductive material is dyeable. Accordingly, the present invention is also directed to a coloured, abrasion-resistant electrically conductive material comprising a natural fibre-containing substrate and an electrically conductive conjugated polymer coating thereon.

The third and fourth aspects of the invention are directed to processes for preparing abrasion-resistant, electrically conductive materials. The third aspect involves providing at least one monomer which is capable of forming an electrically conductive conjugated polymer, and a suitable substrate having a substrate surface, and subjecting the substrate surface to a surface treatment step in order to improve abrasion resistance. The treated surface of the substrate is then exposed to a vapour of the monomer to form an electrically conductive conjugated polymer coating thereon.

The fourth aspect represents a process similar to that of the third aspect, except that to the treated substrate surface is selectively applied a quenching composition to produce a predetermined pattern on the substrate surface. As such, the process of the fourth aspect allows patterning of the conducting polymer on the substrate.

Electrically conductive conjugated polymers

The electrically conductive conjugated polymer coating may be formed from monomers including unsubstituted and substituted thiophene monomers. The polymer coating may be formed from comonomers including a substituted or unsubstituted thiophene monomer, together with other substituted or unsubstituted thiophene, pyrrole or aniline monomers. In one embodiment, the substituted thiophene monomer may carry an alkyl group. In another embodiment, the substituted thiophene monomer may be a 3,4- ethylenedioxythiophene having the following structural formula:

Polymers produced from such monomers, e.g. poly(3,4-ethylenedioxythiophene)

(PEDOT) are highly conductive and highly stable. Relatively thick coatings may exhibit for example, a dark blue colour, whilst thinner coatings may exhibit colour change with the application of low voltage. In another embodiment, a substituted thiophene having the structural formula:

wherein R ¹ and R ² , which may be the same or different, are selected from alkyl groups having from 1 to 25 carbon atoms, and derivatives thereof, may be used.

By altering the substituents R ¹ and R ² , different colours may be generated in polymers formed therefrom. The polymers may vary in colour with the application of low voltage.

In certain embodiments, a series of colours may be generated by, for example by increasing the voltage applied thereto.

In an alternative embodiment, the electrically conductive, conjugated polymer coating may be formed from monomers including substituted or unsubstituted pyrrole monomers. The polymer coating may be formed from comonomers including substituted or unsubstituted pyrrole monomers, together with other substituted or unsubstituted pyrrole, thiophene or aniline monomers.

In one embodiment, the substituted pyrrole monomer may carry an alkyl group. The alkyl group may be in the 3-position. For example, a substituted pyrrole monomer having the structural formula:

H wherein n = 2 to 22, or derivatives thereof, may be used. In various embodiments, n may be selected from the group consisting of: 4, 5, 6, 8, 10, 12, 14, 16 and 22. For example, a ρoly-3-palmitylpyrrole may be used.

Polymers formed from such monomers are generally soluble. By addition of an alkyl chain at the 3-position on the pyrrole, the polymer becomes soluble in organic solvent, thus allowing the polymer to be applied as a liquid to a substrate, e.g. fabric or solid in many different ways, e.g. paint, screen printing, inkjet printing. An example of this is the ability of circuit boards to be printed onto fabrics and any other intricate design. Copolymers of pyrrole and substituted pyrroles, as described above, generally exhibit higher conductivity, though some reduction in solubility may occur. In an alternative embodiment, a substituted pyrrole monomer having the structural formula:

wherein X is a dye moiety, a bridging or cross-linking moiety or chiral group residue, may be used. The substituted pyrrole monomers as described herein represent novel compounds.

Where X is a bridging or cross-linking moiety, the substituted pyrrole monomer may have the structural formula:

For example, where X is -(C _n H _2n )-, a substituted pyrrole monomer having the formula:

wherein n is an integer of 1 to 20, may be used. In one embodiment, n is an integer between 6 and 20.

It will be understood that use of such substituted pyrrole monomers permits cross- linking between polymer chains. However, when a polymer is highly cross-linked, it may become brittle, so for the purposes discussed herein, may be undesirable.

Thus the cross-linked pyrrole monomers may be used as a comonomer with unsubstituted pyrroles or other monomers such as those described herein. By varying the ratios of the substituted pyrrole and normal pyrrole concentrations, a more desirable flexible copolymer may be produced with an increased conductivity due to the cross- linking. The cross-linked copolymer may form a more uniform polymer coating as illustrated below.

Where X is a dye, the dye may function to colour the electrically conductive material. The dye, in this embodiment, may further exhibit increased stability and/or depth of colour.

In a further embodiment, the substituted pyrrole monomer may comprise a fluorescent functionality, via a fluorescent conductive substituent in the 3-position.

The fluorescent conductive substituent may be derived from the fluorescent dyes described above, for example Rhodamine B or Pyrene. In one embodiment, a substituted pyrrole having the structural formula:

may be used. Surface treatment step

It has been surprisingly found that by subjecting the substrate to a surface pre- treatment, e.g. treatment with an oxidant as described below, and conducting a vapour- phase polymerisation, an electrically conductive material is produced exhibiting good abrasion resistance and conductivity.

As stated above, the substrate is a natural fibre-containing substrate, for example a wool-containing fibre, yarn, textile or fabric. The wool-containing material may be a dyed material. An anionic dye may be applied to the material prior to processing. An anionic dye such as Lanasol, Lanaset or Solar dyes, for example Lanasol Yellow 4G, Lanasol Red 6G, Lanasol Blue 35 G, may be used.

The surface treatment step may be of any suitable type. Surface treatments such as corona discharge or the like may be used. In one embodiment, the surface is treated with a suitable oxidant. The oxidant may also function to catalyse the later vapour-phase polymerisation. Accordingly, the process may comprise: subjecting the substrate to an oxidant treatment step.

The oxidant may be selected from one or more of the group consisting of: iron chloride, iron nitrate, antimony chloride, silver nitrate and copper chloride. In one embodiment, the oxidant is iron chloride.

The oxidant treatment step may also comprise: immersing the natural fibre substrate in a solution comprising the oxidant.

Advantageously, the solvent of the solution is an organic solvent which dissolves the oxidant and is easily evaporated. The solvent may be one or more of ethanol, methanol, acetone or butanone.

In one embodiment, the oxidant treatment step further comprises: removing any excess oxidant solution, such that a uniform oxidant to substrate ratio is obtained. The oxidant treatment step may further comprise the step of: drying the substrate after the oxidant is applied.

The substrate, e.g. fibre, may then be placed into an atmosphere that promotes the evaporation of the solvent. Drying may be carried out in a fan- forced environment at an air flow of approximately lOOml/min to 200ml/min. The drying temperature may be in the range of about 2O ⁰ C to about 5O ⁰ C.

Ferric chloride concentrations in the range of approximately 0.5mg/ml to 50 mg/ml of solvent may be used. In an embodiment, the concentration range for the ferric chloride is in the range of approximately 10-30 mg/ml, and the solvent used for the application of ferric chloride is ethanol.

Vapour phase polymerisation

The vapour phase polymerisation step may be conducted in any suitable manner. Advantageously, the monomer vapour is formed by passing an inert gas, e.g. nitrogen or argon, through a liquid of the oxidatively polymerisable compound. The inert gas may be passed through the oxidatively polymerisable compound at a speed of from approximately 10 ml/min to 100 rnl/min. In one embodiment, the inert gas may be passed through the oxidatively polymerisable compound at a speed of approximately 25 ml/min to 80 ml/min. In an alternative embodiment, the inert gas may be passed through the oxidatively polymerisable compound at a speed of approximately 40 ml/min to 60 ml/min. Advantageously, the inert gas is either nitrogen or argon.

The polymerisable monomer may be of any suitable type. The polymerisable monomer may include an oxidatively polymerisable monomer. A substituted or unsubstituted pyrrole monomer, a substituted or unsubstituted aniline monomer, or a substituted or unsubstituted thiophene monomer, or mixtures thereof, may be used. Examples of suitable monomers include those described above.

Advantageously, the substrate is exposed to the vapour of the oxidatively polymerisable compound for a period of approximately 10s to 5 min. In one embodiment, the substrate is exposed to the vapour of the oxidatively polymerisable compound for a period of approximately 1 min to 3 min. In an alternative embodiment, the substrate is exposed to the vapour of the oxidatively polymerisable compound for a period of approximately 2 min to 3 min.

Advantageously, the substrate is exposed to the vapour of the oxidatively polymerisable compound at a temperature in the range of approximately -20°C to 5O ⁰ C. In one embodiment, the substrate is exposed to the vapour of the oxidatively polymerisable compound at a temperature in the range of approximately 0 ⁰ C to approximately 3O ⁰ C. In an alternative embodiment, the substrate is exposed to the vapour of the oxidatively polymerisable compound at a temperature in the range of approximately approximately 10°C to approximately 3O ⁰ C.

The substrate may be exposed to the vapour of the oxidatively polymerisable compound in a sealed chamber, such that any unused compounds may be recycled.

After the polymerization, the coated substrate may be subjected to a further washing step(s), to remove iron ions and thickener. The removal of iron ions may comprise two separate processes. Firstly, the coated substrate may be rinsed with water to remove the thickener and iron ion adsorbed on the surface of the substrate. The iron ions within the fibres of the substrate may then be removed by an acidic solution that contains chelating agents to from complexes with the iron ions.

Various chelating agents such as ethylenediamine tetraacetic acid (EDTA), ethylenediaminedi(o-hydroxyphenylacetic) acid (EDHA), N,N'-bis(2- hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED), Ethylenediamine (EDA), Diethylenetriamine (DETA) and Aminoethylethanolamine (AEEA) etc may be used in this process.

The chelating agent may be provided in a suitable solution, e.g. at a concentration of approximately 5 to 20g/L. Sulfuric acid, nitric acid or hydrochloride acid may be used

to adjust the acidity of the solution. The pH value may be in the range of approximately 1 to 6.

Quenching

In one embodiment, the oxidant treatment in the process of the present invention may be applied to the substrate in a predetermined pattern, for example utilising a template or printing, e.g. screen printing, technique.

It will be understood that patterning the conducting polymer on the substrate is an important technique in the electronic area. It is extensively used to prepare various electronics devices, such as electrical circuit boards, semiconductor microchips and sensor devices. Forming a conductive pattern based on the conducting polymer is important because it will lead to many potential applications that cannot be achieved by metal patterning. For example, patterning the conducting polymer on the fabric may have a minor effect on the textile properties, while patterning a metal on the fabric often leads to alter the handle and comfortable properties of the fabric. A conducting polymer pattern on the textile substrate has many applications. A complex circuit on fabric can be used to prepare a whole-plastic electronic device. To make a multi-functional device in a single piece of fabric need a conducting polymer pattern.

A pattern technique known in the prior art for generating conducting polymer patterns involves a photo-resistive process. A precursor of an oxidant mixing with a polymer such as polyvinyl alcohol was first applied on a substrate to form a uniform polymer composite film. The oxidant precursor was converted to the oxidant under the action of the light (exposure). When a mask was used in this exposure process, an oxidant pattern was formed on the substrate. The patterned oxidant resulted in a conducting polymer pattern when it reacted with the monomers. However, such a pattern technique is only suitable for a flat and hard substrate and the resulting conducting polymer pattern often has low abrasion fastness and poor conductivity because of the involvement of another non-conducting polymer. An effective technique for generating a conducting polymer pattern on the textile-based substrate has not been developed so far. The present invention provides a facile method to produce various conducting polymer patterns on the soft substrates. This technique is especially suitable for generating a

conducting polymer pattern on woven or non-woven textiles. The generated pattern may exhibit one or more of a sharp image, good abrasion fastness and high conductivity. Accordingly, the oxidant treatment step may further comprise: contacting the substrate surface with an oxidant solution, and selectively applying to the substrate surface a quenching composition to produce a predetermined pattern on the substrate surface.

In order to produce an oxidant pattern, a composition that is capable of quenching the polymerization due to deactivation of the oxidant is selectively applied to the substrate. Then, the patterned substrate, e.g. textile is put in contact with the monomer vapour to carry out the polymerization reaction. The conducting polymer is only generated on the area where the oxidant is not quenched. A negative conducting polymer pattern is therefore produced.

In order to form an oxidant pattern, the screen-printing technique is used to selectively quench the oxidant. A standard procedure for screen printing the quenching composition on the oxidant applied textile was used. In order to form a sharp and high resolution picture, a thickener may be added to the quenching composition.

The quenching composition may be of any suitable type. The quenching composition may include a quenching agent, e.g. a high polarity organic solvent or a strong organic base. The quenching agent that is capable of deactivating the oxidant is the main ingredient of the quenching solution. Organic solvents with high polarity or strong organic bases can be used as the quenching agents in this process. The high polarity organic solvents include one or more of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), and the strong organic bases include amines such as ethylene diamine, propyl triamine, tetraethylene triamine, tetraethylene pentamine. The concentration of the quenching agent may be approximately 5 to 35% (w/v). In one embodiment, the concentration of the quenching agent may be approximately 10% to 20% (w/v).

The quenching composition may further comprise a solvent or co-solvent, for example water.

In one embodiment the quenching composition may further comprise a thickener component.

Any water based thickeners used in the screen-printing process are suitable for this purpose, for example one or more of starch, Indalca, Manutex RS, Manutex F, poly vinyl alcohol (PVA), polyethylene oxide (PEO) etc. The concentration of thickener may be in the range of 5% to 30% (w/v). The present invention has scope to be done as a continuous or batchwise process.

Referring to Figure 1 of the drawings, a batch wise vapour-phase coating process 10 consists of the following steps. The first step 11 is to submerge the fibres to be coated into a solution of the oxidant. The next step 12 is to remove the excess oxidant solution to achieve a level oxidant/solvent uptake in all of the fibres. The next step 13 is to evaporate the solvent from the fibre. The next step 14 is to expose the monomer vapour to the fibre in an inert environment for the desired reaction time. The last step 15 is to scour the fabric to remove any excess polymerisation chemicals left in the fabric.

The present invention will now be more fully described with reference to the accompanying examples. It should be understood, however, that the following examples are illustrative only and should not be taken in anyway as a restriction on the generality of the invention described above.

Examples

Example 1 - Coating a pre-dyed wool fabric using pyrrole vapour

Wool fabric was dyed in 3% w/w Lanasol Yellow 4G to produce a yellow wool fabric. This fabric was immersed into a 25 mg/ml ferric chloride/ethanol solution and dried at 2O ⁰ C for 10 min. The treated textile was then put into a chamber and exposed to pyrrole/nitrogen vapour for 3 min. The fabric was then rinsed in water and dried to produce a khaki green wool fabric, with a surface resistance 2 kΩ/cm ² .

Example 2 - Coating a pre-dyed wool yarn using pyrrole vapour Wool yarn was dyed in 1.2% w/w Lanasol Red 6G to produce a red wool yarn.

This yarn was immersed into a 20 mg/ml ferric chloride/ethanol solution and dried at 20°C for 10 minutes. The treated yarn was then put into a chamber and exposed to pyrrole/nitrogen vapour for 3 minutes. The fabric was then rinsed in water and dried to produce a maroon red wool yarn, with a surface resistance of 3 kΩ/cm ²

Example 3 - Coating a pre-dyed wool fabric using pyrrole vapour

Wool fabric was dyed in 1.5% w/w Lanasol Blue 3G to produce a blue wool fabric.

This fabric was immersed into a 30mg/ml ferric chloride/ethanol solution and dried at

20°C for 10 min. The treated fabric was then put into a chamber and exposed to pyrrole/nitrogen vapour for 3 minutes. The fabric was then rinsed in water and dried to produce a navy blue wool fabric, with a surface resistance of 1.2 kΩ/cm ²

Example 4 - Coating fabric using pyrrole vapour

Fabric was immersed into a 15mg/ml ferric chloride/ethanol solution and dried at 2O ⁰ C for 10 min. The treated fabric was then put into a chamber and exposed to pyrrole/nitrogen vapour for 3 min. The fabric was then rinsed in water and dried to produce a grey wool fabric, with a surface resistance of 15 kΩ/cm ²

Example 5 - Coating wool yarn using pyrrole vapour

Wool yarn was immersed into a 40 mg/ml ferric chloride/ethanol solution and dried at 20°C for 10 minutes. The treated yarn was then put into a chamber and exposed to pyrrole/nitrogen vapour for 3 minutes. The yarn was then rinsed in water and dried to produce a black wool yarn, with a surface resistance of 200Ω/cm

Example 6 - Coating wool textile using pyrrole vapour wherein a quenching step is included

The wool textile is immersed into a ferric chloride/ethanol solution (5% w/v) for 10 minutes and then passed through a squeezing machine to remove the excessive amount solution. The textile is then dried under strong wind to produce a dry and uniform ferric chloride coating layer on the wool fibres.

The coated textile is covered by a screen-frame with a pattern images of capital letters 'A ' and then a thick aqueous solution comprising Indalca P A3 (15%, w/v) and tetraethylene triamine (15%, w/v) is applied to the textile by using a standard screen- printing technique. A clear and sharp pattern image is formed on the textile. This textile is then put into a chamber filled with pyrrole vapour for 3 minutes. The conducting polymer is formed on the areas where thickener solution did not cover. A conducting polymer pattern is thus, produced. Above textile is rinsed by water and then put into an acidic solution comprising

EDTA (1% w/v) and sulfuric acid (pH=2) for 30 minutes, to remove traces of iron ions. After drying at 5O ⁰ C for 30min a clear and sharp conducting polymer pattern on the wool

textile is obtained. The pattern shows a resolution of about lmm with electrical conductivity about 500Ω/cm ² .

Example 7 - Coating a pre-dyed wool sample

A wool sample is pre-coated with Rhodamine B then coated via vapour polymerisation, having a surface resistance of ~10 kohms. Coating thickness may be altered to favour either conductivity or fluorescence. See Figure 4.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.