WO2008012518A1

WO2008012518A1 - Fabric comprising metal-coated fibres

Info

Publication number: WO2008012518A1
Application number: PCT/GB2007/002801
Authority: WO
Inventors: Steven Malcolm
Original assignee: W.L. Gore And Associates (U.K.) Limited
Priority date: 2006-07-25
Filing date: 2007-07-24
Publication date: 2008-01-31
Also published as: GB2442298A; GB0614706D0; GB0714358D0

Abstract

There is described a fabric comprising metal-coated fibres wherein the metal-coated fibres are capable of providing shielding from electromagnetic radiation. In particular, the present invention relates to clothing made from a fabric comprising metal -coated fibres, wherein the clothing provides shielding from electromagnetic radiation.

Description

FABRIC COMPRISING METAL-COATED FIBRES

FIELD OF THE INVENTION

The present invention relates to a fabric comprising metal-coated fibres wherein the fabric is capable of providing shielding from electromagnetic radiation. In particular, the present invention relates to clothing made from a fabric comprising metal-coated fibres, wherein the clothing provides shielding from electromagnetic radiation.

BACKGROUND OF THE INVENTION

There is a need for a fabric which provides a wearer with protection from electromagnetic radiation over a wide range of frequencies and wavelengths, and which provides user comfort such as breathability.

For example, in areas with electromagnetic radiation, such as UV or radiation emitted from electricity pylons, there is a need to provide protective clothing for workmen which is comfortable to wear for long periods. Many existing forms of clothing are not breathable, provide limited protection, are not flexible and therefore are uncomfortable to wear over long periods . It is an object of at least one aspect of the present invention to provide a fabric which obviates or mitigates at least one or more of the aforementioned disadvantages .

It is a further object of the present invention to provide a fabric which is capable of providing shielding from electromagnetic radiation.

STJMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a fabric comprising: metal-coated fibres; wherein said fibres are coated with two or more different metals and wherein said fabric is capable of providing shielding from electromagnetic radiation.

Typically, the fabric may provide the function of screening an emission spectrum from a person wearing the fabric and/or protecting a wearer of the fabric from surrounding (i.e. external) electromagnetic radiation. The emission spectrum or electromagnetic radiation may be reduced by more than 50 %, more than 60 %, more than 70 %, more than 80 %, more than 90 %, or more than 95 %.

It has been found that by coating a fibre with two or more different metal coatings may have the effect of providing shielding from electromagnetic radiation and/or reducing an emission spectrum. The fabric may have a plurality or numerous different metal coatings. By emission spectrum is meant any emitted radiation from a wearer of the fabric. By electromagnetic radiation is meant any region of the electromagnetic spectrum. The fabric may therefore provide shielding over any appropriate range of wavelengths of the electromagnetic spectrum spanning from gamma rays to ELF (i.e. extremely low frequency) ranges. Typically, the fabric may provide shielding over the wavelength range of about 1 micron to about 100 metres.

The two or more different metal coatings may be selected from any appropriate metals. Typically, at least one of the metals may provide the function of magnetic screening with another or second metal providing emission screening. The second metal may function to provide a low emission spectrum such as low IR radiation. For example, any combination of transition metals may be chosen. In particular, the metals may be chosen from any combination of the following: Sc; Ti; V; Cr; Mn; Fe; Co; Ni; Cu; Zn; Y; Zr; Nb; Mo; Tc; Ru; Rh; Pd; Ag; Cd; Lu; Hf; Ta; W; Re; Os; Ir; Pt; Au; Hg; and Ac. The metals may therefore be chosen from any of the first, second or third transition series or any combination thereof. Alternatively, the metals may be chosen from any combination of the lanthanides and/or actinides. In alternative embodiments, any combination of metals may be chosen from the elements found in Group I, Group II, Group III (e.g. B, Al) and Group IV (e.g. Ge, Sn, Pb) of the Periodic Table.

The metal coatings on the fibres may substantially completely or partially coat the fibres. Areas of the fibres which have no coating do not provide any shielding. The metal coatings may be substantially smooth and/or highly reflective which may provide improved emissivity and suppression of electromagnetic radiation. In particular embodiments, a first metal coating on the fibre may be that of Ni and a second layer coated on top of the Ni may be Ag. A further alternative is to have a first layer of Pd and a second layer thereon of Ti. The fibres may therefore comprise a first metal coating and a second metal coating. Typically, the first metal coating may provide the effect of magnetic screening and the second metal coating may provide low emissivity. Ni is a preferred first coating. Typically, the second metal coating may also be highly electrically conductive.

The metals forming the coatings may have a purity greater than about 90%, greater than about 95% and preferably greater than about 99%. The first metal coating may have a thickness of about 0.05 μm to about 10 μm or about 0.1 μm to about 0.5 μm. Preferably, the first metal coating may have a thickness of about 0.3 μm. The thickness of the first metal coating may be substantially constant .

The second metal coating may have a thickness of about 0.5 μm to about 10 μm or about 0.1 μm to about 0.5 μm. Preferably, the second metal coating may have a thickness of about 0.3 μm. The thickness of the second metal coating may be substantially constant.

The thickness of the metal coatings may be adapted and tuned for different situations and the wavelength of radiation to be suppressed. The skin depth of the metal coatings may also be taken into consideration when arriving at the optimal thickness for the metal coatings .

The metal-coated fibres may comprise further metal or non-metal layers. Typically, a protective film may be applied over the metal-coated fibres to increase durability. For example, a plastics or polymer coating may be provided on top of the metal-coated fibres such as any good abrasion resistant material . For example, a fluoropolymer, Teflon (Trade Mark) , PTFE or expanded PTFE may be used. In particular, the protective film may be polydimethyl siloxane/polyacrylate. Moreover, a colour print may also be provided on top of the metal-coated fibres. The colour print may be for aesthetic appearance. Typically, the metal-coated fibre may be in the form of a woven or non-woven fabric, felt or knit material. The fabric may be flexible providing comfort to a user wearing the fabric . In particular embodiments such as where the fabric is a woven fabric, at a microscopic level, the surface of the fabric is capable of forming a diffuse spectrum from emitted radiation from a wearer of the fabric or from any surrounding electromagnetic radiation. The surface of the fabric may be substantially non-flat due to interlacing fibres of the weave. Therefore, at a microscopic level the surface of the fabric may be substantially undulating or angulated due to, for example, the weave of the fabric. The fabric may comprise substantially perpendicularly oriented interlacing fibres in the weave. For example, there may be about 5 to 20 metal coated fibres in each of the substantially perpendicularly oriented interlacing parts of the woven fabric. The 5 to 20 fibres may be oriented substantially collinear and may have a width of about 0.1 to 0.5 mm. The weave in the fabric may therefore provide a substantially roughened surface at a microscopic level due to the undulating surface caused by the weave.

The fibres may be any suitable natural or synthetic fibre or a combination thereof. For example, the fibres may be formed from any suitable polymer such as polyamides (e.g. nylon), polyesters, polyacrylates, fluoropolymer (e.g. PTFE or expanded PTFE) or any combination thereof.

The uncoated fibres may have a cross-sectional diameter of about 5 μm to 50 μm, about 15 μm to 25 μm or about 20 μm.

The fabric may also comprise an additional layer which may be waterproof and/or water repellent. This additional layer may be located on top of the metal coated fibres. The fabric may therefore be substantially waterproof and/or substantially water repellent. The additional layer may also be windproof. For example, this additional layer may be any suitable polymer such as a fluoropolymer. In particular embodiments this layer may be formed from PTFE or expanded PTFE. For example, the additional layer may be Gore Tex (Trade Mark) expanded PTFE membrane. Alternatively, the additional layer may be polyester based. The additional layer may have a thickness of about 0.05 μm to about 10 μm. Preferably, the thickness of the additional layer may be about 5 μm. The metal-coated fibres may be bonded to the additional layer using any form of adhesive or spot welding. For example, any appropriate synthetic adhesives may be used. Alternatively, thermoplastic webs, sewing or stitching may be used to attach the additional layer. The fabric may also comprise a base layer in the form of, for example, a woven or knit layer. For example, a knit nylon base layer may be used. Typically, the base layer may have a thickness of about 0.1 mm to about 1 mm, or preferably about 0.25 mm. The base layer may be attached using any appropriate adhesive means, spot welding, thermoplastic webs, or sewing or stitching.

The fabric may therefore be in the form of a laminate with a plurality of different layers. The fabric may be breathable, flexible and comfortable to wear over long periods.

The fabric may also be in the form of patches which may be attached to existing garments such as jackets.

According to a second aspect of the present invention there is provided a method of forming a fabric comprising: providing a length of fibre; applying a first metal coating onto the fibre; applying a second metal coating on top of the first metal coating to form a fibre with a first and second metal coating; forming a fabric with said fibre comprising first and second metal coatings; wherein said fabric provides shielding from electromagnetic radiation. Typically, the first metal coating may be applied by any appropriate means such as using standard deposition techniques. The second metal layer may also be applied by any suitable means. For example, any of the following techniques may be used: vacuum metallisation; sputtering; plasma treatment; electroless deposition; and electrolytic plating.

The fabric may be woven into a woven fabric, knitted in a knit material or formed into a felt using any appropriate means.

Once the metal-coated fibres have been, for example, woven, an additional layer such as waterproof and/or water repellent layer may be applied. For example, a fluoropolymer such as Gore Tex (Trade Mark) expanded PTFE membrane may be used. Alternatively, the waterproof and/or water repellent layer may be a polyester.

A base layer such as a knit layer in the form of nylon base layer may also be attached to the fabric.

The different layers may be adhered using adhesive, discrete adhesive dots, thermoplastic webs, sewing or stitching.

According to a third aspect of the present invention there is provided a garment made from a fabric, said fabric comprising: metal-coated fibres; wherein said fibres are coated with two or more different metal coatings and said fabric is capable of providing shielding from electromagnetic radiation.

The garment may be any suitable article of apparel such as a jacket, trousers, hats, gloves, boots, shoes, socks, underwear, vests and face coverings such as face masks (e.g. ski masks).

The garments made from the fabric according to the present invention may therefore provide shielding from electromagnetic radiation over a wide range of frequencies and wavelengths. For example, the garments may reduce or substantially reduce an IR emission spectrum from a person wearing the garment or from surrounding electromagnetic radiation. The garments may therefore function as a shield.

The garments according to the present invention also have a number of further technical advantages . For example, due to the protection from electromagnetic radiation, the garments made according to the fabric may act as a barrier to a surrounding hot temperature environment such as in a desert. Therefore, the garments provide protection and cooling from hot temperatures. Moreover, in the event of cold sub-zero temperatures, the garments once again provide protection from this cold environment allowing a wearer of such a garment to remain warm. The garments according to the present invention may therefore provide protection in both cold and hot environments .

The garments may be completely or only partially coated with fabric containing the metal coated fibres. According to a fourth aspect of the present invention there is provided a structure made from a fabric, said fabric comprising: metal-coated fibres; wherein said fibres are coated with two or more different metal coatings and said fabric provides shielding from electromagnetic radiation.

A variety of structures may be formed using the fabric according to the present invention. For example, , tents and shelters may be formed using the fabric. A sleeping bag may also be formed. The tents and shelters may therefore shield the emission spectrum of a person located within the tent or shelter or protect the person from electromagnetic radiation outside of the tent or shelter. The tents and shelters may also provide protection from cold and hot environments.

The fabric according to the present invention may also be used as a surrounding enclosure for a room in a building. Due to the shielding effect of the fabric, the fabric may therefore provide a highly secure room within which electromagnetic signals emitted from computers and other electronic devices may be securely retained therein. For example, the fabric according to the present invention may provide a Faraday cage within which highly secure computer activities may be conducted. Due to the shielding effect of the fabric, substantially all electromagnetic radiation may be retained within the enclosure formed by the fabric thereby preventing data being intercepted by third parties .

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a cross-sectional view of a fabric according to an embodiment of the present invention; Figure 2 is a cross-sectional view of a metal-coated fibre according to a further embodiment of the present invention;

Figure 3 is an SEM image of a woven layer in a fabric according to a yet further embodiment of the present invention;

Figure 4 is a cross-sectional view of the fabric shown in Figure 3 ; and

Figure 5 is an expanded view of a fibre shown in the fabric of Figures 3 and 4. DETAILED DESCRIPTION

Figure 1 is a cross-sectional representation of a fabric, generally designated 100. As shown in Figure I₁ the fabric 100 comprises a base layer 110, a middle layer 112 and an outer layer of woven filaments 114.

Base layer 110 is a knit layer of nylon with a thickness of about 0.25 mm. Layer 112 is a waterproof, water repellent and windproof layer. The layer 112 is formed from Gore Tex (Trade Mark) expanded PTFE membrane with a thickness of about 5 μm.

The filaments 114 are formed from polyamide and have a cross-sectional diameter of about 10 μm.

Figure 2 is a cross-sectional view of the filaments 114. The filaments 114 comprise a central core layer 116, a first metal layer 118 and a second metal layer 120. The central core layer has a diameter of about 10 μm and is formed from polyamide. The first metal layer 118 is formed from Ni and has a thickness of about 0.3 μm. The first layer of nickel has the function of providing magnetic screening. The second metal layer 120 formed from Ag has a thickness of 0.3 μm and provides effective electrical shielding.

The fabric 100 with the outer layer comprising the woven filaments 114 is capable of providing the fabric 100 with low emissivity for electromagnetic radiation such as IR. The fabric is therefore capable of screening IR radiation.

Figure 3 is an SEM image of a further fabric 200 with woven filaments 214. As shown in Figure 3, the filaments 214 are woven into a regular pattern of interlacing fibres substantially covering all of the outer surface of the fabric 200 thereby providing a reduction in the emissivity over the whole structure of the fabric 200. Figure 4 is a cross-sectional view of the fabric 200. Figure 4 shows that there is the base knit layer 210 with a thickness of about 0.25 mm and a middle layer of Gore Tex (Trade Mark) expanded PTFE membrane 212 with a thickness of about 5 μm. The outer layer comprises the filaments 214 with the metal coatings.

Figure 5 is an enlarged SEM image of a filament 214.

As shown in Figure 5, the filament 214 comprises a first metal layer of Ni with a thickness of about 0.3 μm and a second metal layer of Ag with a thickness of about 0.3 μm.

As discussed, articles of apparel such as any form of garment may be formed using the fabric according to the present invention. Garments such as jackets, trousers, gloves, socks, shoes, boots, hats, underwear, vests and face protective coverings such as ski masks may be formed using the fabric. A particular use of the fabric is to provide protection for workmen performing maintenance on electricity pylons. Electricity pylons emit potentially harmful electromagnetic radiation which is thought to cause some cancers. Therefore, to protect workmen performing maintenance work on electricity pylons, the workmen may wear garments formed using the fabric according to the present invention. The fabric substantially blocks or screens the electromagnetic radiation.

The fabric according to the present invention is also used in the construction of tents and shelters. As the fabric provides protection from electromagnetic radiation, the tents and shelters provide the function of screening an emission spectrum from persons within the tents or shelters and/or protecting persons located within the tents and shelters from external electromagnetic radiation outside of the tents and shelters. The tents and shelters may also provide protection from extreme hot and cold conditions.

A further use of the fabric according to the present invention is to provide a protective environment within which electrical devices may be operated. For example, the electrical devices may be computers, phones or other electronic equipment. As the fabric provides protection from electromagnetic radiation, the fabric provides the effect of a Faraday cage thereby preventing third parties from intercepting signals and information.

It has been found that the fabric according to the present invention may provide protection across the full spectrum of the electromagnetic radiation but is particularly useful in the wavelength range of 3 μm to several hundred metres. The radiation is reduced to less than 5% and preferably less than 1% of the initial radiation. Whilst specific embodiments of the invention have been described above, it will be appreciated that departures from the described embodiments may still fall within the scope of the invention. For example, any suitable combination of metals which provide the required protection from electromagnetic radiation may be used. Additionally, the thicknesses of the metal layers may be adapted for different wavelengths and frequencies of electromagnetic radiation.

Claims

1. A fabric comprising: metal-coated fibres; when said fibres are coated with two or more different metals and wherein said fabric is capable of providing shielding from electromagnetic radiation.

2. A fabric according to claim 1, wherein the fabric provides the function of screening an emission spectrum from a person wearing the fabric and/or protecting a wearer of the fabric from surrounding electromagnetic radiation.

3. A fabric according to any of claims 1 or 2, wherein the metal-coated fibres comprise a plurality of different metal coatings .

4. A fabric according to any preceding claim, wherein a first metal coating provides the function of magnetic screening and a second metal coating provides the function of providing a low emission spectrum from IR radiation.

5. A fabric according to any preceding claim, wherein the metal selected to form the metal-coated fibres may be selected from any combination of first, second or third transition series.

6. A fabric according to any preceding claim, wherein the metals used to form the metal-coated fibres are selected from any one of or combination of the following: Sc; Ti; V; Cr; Mn; Fe; Co; Ni; Cu; Zn; Y; Zr; Nd; Mo; Tc; Ru; Rh; Pd; Ag; Cd; Lu; Hf; Ta; W; Re; Os; Ir; Pt; Au; Hg; and Ac .

7. A fabric according to any of claims 1 to 4, wherein the metal forming the metal-coated fibres is selected from any one . of or combination of the lanthanides and/or actinides .

8. A fabric according to any of claims 1 to 4, wherein the metals used to form the metal-coated fibres are selected from any one of or combination of Group I, Group II, Group III and Group IV elements.

9. A fabric according to any preceding claim, wherein metal layers forming the metal-coated fibres are substantially highly reflective which improves suppression of electromagnetic radiation.

10. A fabric according to any of claims 1 to 4, wherein a first metal coating on the fibre is Ni and a second metal coating is Ag.

11. A fabric according to any of claims 1 to 4, wherein a first metal coating is Pd and a second metal coating layer is Ti .

12. A fabric according to any preceding claim, wherein the metals forming the metal-coated fibres have a purity of greater than about 99%.

13. A fabric according to any preceding claim, wherein a first metal coating has a thickness of about 0.1 μm to about 0.5 μm and a second metal coating has a thickness of about 0.1 μm to about 0.5 μm.

14. A fabric according to any preceding claim, wherein the metal-coated fibres comprise a protective film.

15. A fabric according to any preceding claim, wherein the metal-coated fibres are in the form of a woven or non-woven fabric, felt or knit material.

16. A fabric according to any preceding claim, wherein the fabric comprises an additional layer in the form of a waterproof and/or water repellent layer.

17. A fabric according to any preceding claim, wherein the fabric comprises a base layer in the form of a woven or knit layer.

18. A fabric according to any preceding claim, wherein the fabric is capable of forming a diffuse spectrum from emitted radiation from a wearer of the fabric or from any surrounding electromagnetic radiation.

19. A method of forming a fabric comprising: providing a length of fibre,- applying a first metal coating onto the fibre; applying a second metal coating on top of the first metal coating to form a fibre with a first and second metal coating; . forming a fabric with said fibre comprising first and second metal coatings; wherein said fabric provides shielding from electromagnetic radiation.

20. A method according to claim 19, wherein the metal coatings are applied using any of the following technique: vacuum metallisation; sputtering; plasma treatment; electroless deposition; and electrolytic plating.

5 21. A method according to any of claims 19 or 20, wherein the metal-coated fibres are formed into a woven or non-woven structure, knit or felt.

22. A method according to any of claims 19 to 21, 10 wherein an additional layer in the form of a waterproof and/or water repellent layer is added to the fabric.

23. A method according to any of claims 19 to 22, wherein a base layer in the form of a knit layer is added

15 to the fabric.

24. A garment made from a fabric comprising: metal-coated fibres; wherein said fibres are coated with two or more 20 different metal coatings and said fabric is capable of providing shielding from electromagnetic radiation.

25. A garment according to claim 24, wherein said garment is selected from any of the following: jacket; !5 trousers; hats; gloves; b.oots; shoes; socks; underwear; vests; and face coverings in the form of face masks.

26. A structure comprising a fabric, said fabric comprising: metal-coated fibres; wherein said fibres are coated with two or more different metal coatings and said fabric is capable of providing shielding from electromagnetic radiation.

27. A structure according to claim 26, wherein said structure is selected from any of the following: tents; shelters or any form of building coverings or linings.

28. A structure according to any of claims 26 or 27, wherein the structure substantially prevents electromagnetic radiation penetrating therethrough thereby preventing third parties from intercepting signals from electrical and/or electronic devices.