Flocked activated carbon fibre materials

Abstract

The invention relates to a layered material, in particular one comprising activated carbon fibres which form a layer of flocked activated carbon fibres on a base material. Also provided are methodologies for making such materials, for example including applying an adhesive to a base fabric layer; applying activated carbon fibres to the adhesive on the base fabric layer; and curing the adhesive. Garments comprising the present material are also provided.

Description

[0001] FLOCKED ACTIVATED CARBON FIBRE MATERIALS

[0002] Field of the Invention

[0003] The present invention relates to materials comprising flocked activated carbon fibres, a production method for materials comprising flocked activated carbon fibres, and garments comprising such materials.

[0004] Background

[0005] Materials comprising activated carbon are useful for the adsorption of harmful and toxic agents. They are of importance in several sectors including, but not limited to: chemical air filtration; the production of materials for protection against chemical, biological, radiological and nuclear (CBRN) materials and agents; the production of materials for protection against carcinogenic fire effluents; the production of protective clothing for First Responders, such as firefighters, paramedics, and police officers, or military personnel, construction workers, workers in incineration plants; and the production of materials for First Responder equipment.

[0006] Activated carbon materials that are comprised in the state-of-the-art achieve improved performance by increasing activated carbon weight and carbon depth, where increased activated carbon weight and depth can provide an increased adsorption capacity. However, that is in balance with the need to minimise accompanying deleterious effects on attributes such as material comfort for a user, material handle (the feel of the material), total weight, flexibility, and breathability. As the amount of activated carbon increases, it becomes hard to maintain these desirable properties. Furthermore, the cost of producing the items is increased, which is particularly undesirable because they are often intended to be disposable items.

[0007] Known activated carbon materials include activated carbon fibre fabrics. Activated carbon fibre fabrics are formed from yarns, fibres, knitted, woven or nonwoven fabrics that are typically formed from precursor materials such as polyacrylonitrile (PAN), pitch, cellulosic materials such as viscose rayon and acetates, poly(vinylidene chloride (PVDC), and phenolic resins. These materials are subjected to a carbonisation and activation process to produce the activated carbon fibre fabric.

[0008] However, activated carbon fibre fabrics are expensive to produce and can only achieve a minimal depth profile in activated carbon (i.e. no greater than the thickness of the precursor fabric itself). Furthermore, activated carbon fibre fabrics are fragile. They are not durable and require additional protection to prevent degradation.

[0009] Other known activated carbon fabrics include materials comprising a base fabric onto which spherical carbon is deposited. The carbon depth and activated carbon density can in principle be increased by increased loading of spherical activated carbon. However, if a material is produced in this way, then it is significantly compromised in material handle, flexibility and comfort. It is further difficult to achieve a uniform carbon depth over the surface of a base fabric, and the spherical carbon can easily re-distribute because it is not well secured to the base fabric. Spherical carbon is also relatively expensive to produce.008915449

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[0011] Similarly, a material may be produced by the loading of activated carbon powder applied as a binder system to a base fabric. The carbon depth and activated carbon density can in principle be increased by increased loading of powdered activated carbon. However, if a material is produced in this way, then it is significantly compromised in material handle, flexibility and comfort. It is further difficult to achieve a uniform carbon depth over the surface of a base fabric, and the activated carbon powder can easily redistribute because it is not well secured to the base fabric.

[0012] The present invention has been devised in the light of the above considerations.

[0013] Summary of the Invention

[0014] The inventors have developed a layered material comprising a base fabric layer onto which activated carbon fibres are deposited to form a layer of flocked activated carbon fibres. That is, there is a layer of ‘base fabric’ and a layer of ‘flocked activated carbon fibres’. Flocked activated carbon fibres create a high surface density of activated carbon, and a high surface area for adsorption, without negatively impacting the flexibility (or drape) or the handle (or feel) of the base fabric. This material offers excellent adsorption capacity that may be substantially uniform over the entire flocked surface, at relatively low production cost. The properties of the chosen base fabric (its durability, flexibility, handle, amongst other attributes) are not compromised and the base fabric can be chosen freely. The flocked activated carbon fibres provide the fabric with desired adsorption and filtration properties for protection of a user against harmful agents.

[0015] A first aspect of the invention provides a layered material, comprising:

[0016] i. a base fabric layer (a);

[0017] ii. activated carbon fibres, each activated carbon fibre being adhered at a fibre end to one side of the base fabric (a) to form a layer of flocked activated carbon fibres;

[0018] wherein an activated carbon weight of the layered material is 50 gsm to 200 gsm.

[0019] In some embodiments, the activated carbon weight of the layered material is 80 gsm to 150 gsm, and in some embodiments the activated carbon weight of the layered material is 100 gsm to 120 gsm.

[0020] A layered material of the invention provides excellent adsorption and filtration properties without comprising the flexibility, drapability or handle of the base fabric substrate.

[0021] In some embodiments, the base fabric layer (a) comprises a knitted fabric. A knitted fabric is composed of loops of continuous yarn. This contrasts with woven fabrics, which are composed of warp and weft yarns that are interlaced. It is also contrasts with nonwoven fabrics, which are composed of tangled or bonded fibres. Because of the structure of a knitted fabric, it is naturally stretchy in all directions and is also drapable. Woven fabrics are less likely to stretch (unless they are composed of elastomeric fibres), and do not easily return to their non-stretched state, and they are less drapable. Nonwoven fabrics cannot easily be stretched and cannot easily be draped. A knitted fabric is therefore beneficial as it may008915449

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[0023] be manipulated by stretching or curving prior to flocking to increase flocked fibre density. A knitted fabric is also beneficial because it provides a layer that is comfortable next to the skin.

[0024] In some embodiments, the base fabric layer (a) is impregnated with activated carbon. When the base fabric layer (a) is impregnated with activated carbon, the total adsorption capacity of the layered material is increased.

[0025] In some embodiments, there is no activated carbon powder deposited on the surface of the base fabric between the activated carbon fibres in the layer of flocked activated carbon fibres. When there is no activated carbon powder deposited on the surface of the base fabric between the flocked activated carbon fibres the flexibility and handle of the base fabric layer is not compromised. Flocking at the densities described herein can obviate the need for further activated carbon deposition(s) to achieve the desired protective properties.

[0026] In some embodiments, the average fibre length of the activated carbon fibres is 0.10 mm to 5.0 mm, optionally wherein the average fibre length of the activated carbon fibres is 0.25 to 3.0 mm. The fibre length of the activated carbon fibres determines the carbon depth of the layered material, and, for a given flock density, as the fibre length is increased the adsorption capacity is increased. The carbon depth of the layered material can be controlled and adapted to suit different requirements by variation in fibre length.

[0027] In some embodiments, the activated carbon fibres are substantially the same length. In some embodiments, the activated carbon fibres are about the same length. When the activated carbon fibres are substantially the same length or about the same length, the uniformity of carbon depth is increased across the layered material, resulting in substantially uniform adsorption properties over the layered material.

[0028] Fibres are cropped to a uniform length by feeding a tow of filaments at a controlled speed relative to the shearing blades. This control results in the fibres being substantially the same length or about the same length.

[0029] In some embodiments, the activated carbon fibres have lengths ranging from 0.08 mm to 0.12 mm. In some embodiments, the activated carbon fibres have lengths ranging from 0.4 mm to 0.6 mm. In some embodiments, the activated carbon fibres have lengths ranging from 0.8 mm to 1.2 mm. In some embodiments, the activated carbon fibres have lengths ranging from 1.6 mm to 2.4 mm. In some embodiments, the activated carbon fibres have lengths ranging from 2.8 mm to 4.2 mm. In some embodiments, the activated carbon fibres have lengths ranging from 4 mm to 6 mm. When the activated carbon fibres satisfy these ranges, the uniformity of carbon depth is increased across the layered material, resulting in substantially uniform adsorption properties over the layered material.

[0030] In some embodiments, the minimum fibre length of the activated carbon fibres is no more than 5%, 10% or 20% less than the average fibre length. In some embodiments, the maximum fibre length of the activated carbon fibres is no more than 5%, 10% or 20% greater than the average fibre length. When the008915449

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[0032] activated carbon fibres satisfy these ranges, the uniformity of carbon depth is high across the layered material, resulting in substantially uniform adsorption properties over the layered material.

[0033] In some embodiments, the carbon depth is substantially uniform over the surface of the layered material. In some embodiments, the layered material additionally comprises a protective fabric layer (b), arranged so that the layer of flocked activated carbon fibres is between the base fabric layer (a) and the protective fabric layer (b). A protective fabric layer (b) provides an additional physical barrier before, for example, chemical agents reach the layer of flocked activated carbon fibres. The protective layer (b) slows the passage of agents, such as CBRN agents or fire effluents, through the layered material. A protective fabric layer (b) may also protect the layer of flocked activated carbon fibres so that the fibres are less likely to degrade, or so that impacts to the material are less likely to result in loss of flocked activated carbon fibres.

[0034] In some embodiments of the invention comprising a protective fabric layer (b), the protective fabric layer (b) may be impregnated with activated carbon. By impregnating the protective fabric material (b) with activated carbon, the total adsorption capacity and filtration performance of the layered material is enhanced.

[0035] In some embodiments of the invention comprising a protective fabric layer (b), a fibre end that is not adhered to the base fabric layer (a) may be adhered to the protective fabric layer (b). Where an activated carbon fibre in the layer of flocked activated carbon fibres is adhered at one end to the base fabric layer (a) and at the other end to the protective fabric layer (b), this contributes to improved strength of the layered material and a reduced likelihood that the flocked activated carbon fibres will redistribute.

[0036] The invention further provides a process to produce a layered material, wherein the process comprises: (A) applying an adhesive to a base fabric layer (a);

[0037] (B) applying activated carbon fibres to the adhesive on the base fabric layer (a), such that each activated carbon fibre is adhered at a fibre end to the base fabric layer (a) to form a layer of flocked activated carbon fibres, optionally wherein:

[0038] (i) the base fabric layer (a) is curved and the activated carbon fibres are applied to a convex face of the curved base fabric layer (a); and / or

[0039] (ii) the base fabric layer (a) is stretched and the activated carbon fibres are applied to a stretched surface of the base fabric layer (a);

[0040] and

[0041] (C) curing the adhesive.

[0042] When the base fabric layer is curved and / or stretched prior to the application of activated carbon fibres, the density of the layer of flocked activated carbon fibres may be controlled and maximised if desired. Once flocking is complete, the base fabric layer may be returned to a substantially flat and / or nonstretched state.

[0043] In some embodiments, the process additionally comprises a step (D) in which a protective fabric layer (b) is applied to the layer of flocked activated carbon fibres. A protective fabric layer provides an additional008915449

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[0045] physical barrier to, for example, CBRN agents or fire effluents, and also protects the layer of flocked activated carbon fibres from damage and / or degradation.

[0046] In some embodiments, a layer of adhesive is applied to the protective fabric layer (b) before application to the layer of flocked activated carbon fibres, such that after the application, the layer of adhesive is between the protective layer (b) and the layer of flocked activated carbon fibres. This allows for a fibre end that is not adhered to the base fabric layer (a) to be adhered to the protective fabric layer (b), which contributes to improved strength of the layered material.

[0047] The invention also provides a garment comprising the layered material of the invention. A garment comprising the layered material of the invention exhibits excellent adsorption and filtration properties without compromising material flexibility and handle. No additional functional layers are required and the garment is comfortable for the user.

[0048] The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0049] Detailed Description of the Invention

[0050] Aspects and embodiments of the present invention will now be discussed. Further aspects and embodiments will be apparent to those skilled in the art.

[0051] A first aspect of the invention provides a layered material, comprising:

[0052] i. a base fabric layer (a);

[0053] ii. activated carbon fibres, each activated carbon fibre being adhered at a fibre end to one side of the base fabric (a) to form a layer of flocked activated carbon fibres;

[0054] wherein an activated carbon weight of the layered material is 50 gsm to 200 gsm. In some embodiments, the activated carbon weight of the layered material is 80 gsm to 150 gsm, and in some embodiments the activated carbon weight of the layered material is 100 gsm to 120 gsm.

[0055] The layer of flocked activated carbon fibres provides the layered material with excellent adsorption capacity and filtration properties, without compromising the desirable attributes of the base fabric in terms of fabric flexibility (or drape), fabric handle (or feel), and fabric durability. The surface area on which adsorption can take place, and the fabric flexibility and handle, is increased relative to fabrics comprising other forms of activated carbon at the same activated carbon weight.

[0056] The close packing of the flocked fibres also means the fibres can trap and hold liquid droplets due to the capillary effect. This extends the contact time of a challenge agent with the material and increases adsorption capacity.

[0057] The activated carbon fibres are secure on the base fabric and the layer of flocked activated carbon fibres is durable.008915449

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[0059] “Flocked activated carbon fibres” herein means activated carbon fibres which are deposited on the surface of the base fabric (a) by a flocking procedure.

[0060] Flocking is a well known procedure in the textiles industry. It involves the application of fibres onto a base fabric that is coated with adhesive. One fibre end of each fibre is adhered to the base fabric in a flocking step.

[0061] Flocking may be achieved, for example, by an electrostatic method or by a mechanical method.

[0062] In an electrostatic method, a charge is applied to the fibres whilst the base fabric substrate is earthed. The charged fibres repel each other, align along the electric field lines, and strike the earthed base fabric substrate. They become substantially vertically anchored in the adhesive on the base fabric substrate. In a mechanical method, fibres are deposited on a base fabric substrate, for example by sprinkling onto the adhesive by means of a hopper, with vibration of the substrate by means of a beater bar so that the fibres become oriented substantially perpendicularly to the base fabric substrate.

[0063] After deposition of the fibres, the adhesive is cured. In the resultant flocked fabric, one fibre end of the flocked fibre is adhered to the base fabric substrate, and the fibres are substantially perpendicularly aligned.

[0064] Herein, a flocked fabric is a layered material which comprises a layer of base fabric onto which fibres are deposited, each fibre being adhered at a fibre end to the base fabric to form a layer of flocked fibres. That is, there is a layer of ‘base fabric’ and a layer of ‘flocked fibres’. In the invention, there is a layer of ‘base fabric’ and a layer of ‘flocked activated carbon fibres’.

[0065] In the invention, a carbon depth of the layered material can be easily controlled; a single fibre deposited at a fibre end to the base fabric provides a carbon depth that is approximately equal to the length of that fibre, and the production of activated carbon fibres of a particular and controlled length is well known in the art. As a result, a layered material can be produced with relatively large carbon depth (to increase adsorption capacity or filtration performance), or with relatively small carbon depth (to reduce overall weight whilst maintaining an acceptable level of performance). The layered material may be prepared with carbon depths that are variable across the surface of the material. Different carbon depths may be desirable in different areas of a layered material depending on use. For example, in certain areas it may be more desirable to reduce weight and maximise breathability than to increase adsorption capacity or filtration performance. This may be the case, for example, in items of protective clothing wherein certain areas of the layered material that are less exposed to hazards (such as under arms, or on soles of feet, for example) may not require a large carbon depth.

[0066] Activated carbon fibres of the invention are produced more cheaply than activated spherical carbon. The production of activated carbon fibres is known in the art. A continuous carbonized fibre (continuous-CF) may be a starting material. The continuous-CF may be based on a material such as polyacrylonitrile (PAN) and appear in the form of tow, comprising thousands of monofilaments. This continuous-CF may first undergo an unwinding process, before treatment with a sizing agent. After addition of the sizing agent, the continuous-CF may be dried to remove water solvent, and then the continuous-CF may be008915449

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[0068] chopped with a blade to produce activated carbon fibres of a predetermined length. The carbon fibres may be activated by physical activation or by chemical activation. Physical activation may be by pyrolysis at high temperature in an inert atmosphere, or by heating in an oxidising atmosphere. Chemical activation may be impregnation with chemicals before heating. The activation process produces the small, low-volume pores that allow for adsorption.

[0069] In contrast to the use of spherical activated carbon or activated carbon powder, an achieved carbon depth of the layered material of the invention can be relatively large without compromising the properties of the underlying base fabric. Achieving the same carbon depth with forms of activated carbon such as spherical or powdered carbon is not possible without compromising the flexibility or handle of the base fabric.

[0070] Furthermore, the layered material of the invention is also more durable than materials which attempt to produce the same carbon depth but using spherical carbon or activated carbon powder. Activated carbon in the form of spherical or powdered carbon that sits furthest from the base fabric is often not secure and can easily be lost or re-distributed over the fabric surface. By contrast, the activated carbon fibres of the invention are secure on the base fabric due to their flocking and cannot be re-distributed or lost unintentionally.

[0071] A relatively large carbon depth allows for longer adsorption periods (contact time with the layer of activated carbon fibres is longer) and this results in improved performance; fewer harmful substances can travel through the material.

[0072] It may be desirable to produce a layered material wherein the layered material has an activated carbon weight that is relatively high (for example, towards the upper end of a range, for example, about 120 gsm, 150 gsm, or 200 gsm), so that the adsorption capacity and filtration performance of the material is maximised. Such embodiments may be preferable for use in more challenging environments, where the exposure to CBRN agents or fire effluents, for example, is more intense (more concentrated or over a longer period). Increasing the activated carbon weight for improved adsorption properties is balanced, however, with the associated increase in overall garment weight and the likelihood of heat stress arising from the increased insulative properties of the material.

[0073] It may be desirable to produce a layered material wherein the layered material has an activated carbon weight that is relatively low (for example, towards the lower end of a range, for example about 50 gsm, 80 gsm, or 100 gsm), so that the overall weight and any unwanted insulative properties of the layered material are minimised without compromising adsorption or filtration performance too greatly. Such embodiments may be preferable for uses in less challenging environments where the adsorption capacity or filtration performance of the layered material does not need to be maximised. Embodiments in which the activated carbon weight is relatively low still provide advantages compared to materials of similar activated carbon weight composed of other forms of activated carbon in terms of cost and fabric flexibility (or drape) and handle (or feel). The cost of production is also reduced where the activated carbon weight of the layered material is relatively low.008915449

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[0075] Each activated carbon fibre is adhered at a fibre end to the one side of the base fabric (a) via an adhesive on the base fabric (a). The adhesive may be based on an aqueous binder system including, but not limited to, acrylic, vinyl acetate ethylene (VAE), or polyurethane dispersion (PUD). The adhesive may be a hot melt (thermoplastic) adhesive.

[0076] In some embodiments of the invention, the base fabric layer (a) comprises a knitted fabric. A knitted fabric is composed of loops of continuous yarn. This contrasts with woven fabrics, which are composed of warp and weft yarns that are interlaced. It is also contrasts with nonwoven fabrics, which are composed of tangled or bonded fibres. Because of the structure of a knitted fabric, it is naturally stretchy in all directions and is also drapable. Woven fabrics are less likely to stretch (unless they are composed of elastomeric fibres), and do not easily return to their non-stretched state, and they are less drapable. Nonwoven fabrics cannot easily be stretched and cannot easily be draped. A knitted fabric is therefore particularly advantageous in manufacture because it may be easily curved and / or stretched during the flocking process such that the density of flocked activated carbon fibres can be maximised, and hence the activated carbon weight of the layered material maximised for a given carbon depth. Alternatively, the flocked fibre density may be easily controlled by varying the degree of stretching or curving of the knitted base fabric layer (a) prior to flocking. A knitted base fabric layer (a) also provides excellent levels of comfort for a user wearing a garment comprising a knitted base fabric layer (a). The knitted fabric may be weft knitted or it may be warp knitted; both offer high levels of comfort. This reduces the need for additional layers that would otherwise be required to increase the comfort of an activated carbon material. In some embodiments of the invention, the base fabric layer (a) is impregnated with activated carbon. By impregnating the base fabric material (a) with activated carbon, the adsorption capacity and filtration performance of the layered material is enhanced. There is a second opportunity for the layered material to adsorb agents which are not successfully adsorbed by the layer of flocked activated carbon fibres. The impregnation of the base fabric (a) does not compromise the handle, flexibility or drapability or other desirable attributes of the base fabric (a), and the impregnated activated carbon is fixed within the base fabric; it is not susceptible to redistribution in the material or loss from the material. The activated carbon that is used to impregnate the base fabric layer (a) may be in the form of activated carbon fibres, or may be in a different form (such as activated carbon powder or spherical activated carbon). Where the activated carbon that is impregnated in the base fabric is of a different form to the flocked activated carbon layer, each type may be optimised for the adsorption or filtration of different agents.

[0077] Methods to form an impregnated base fabric material are known in the art. Typically, an aqueous slurry of a fine particle activated carbon powder is formed, to which a synthetic latex is added. A base fabric material may then be impregnated with the resultant slurry comprising latex, before drying and curing. Atypical method of impregnation is a process known as paddling, in which a base fabric material is passed through a trough containing the slurry, before being passed through a mangle to squeeze out any excess. Drying can be achieved by various means, including by steam cans or by hot air drier, and this step may also act to cure the material.008915449

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[0079] In some embodiments of the invention, the layered material comprises no activated carbon powder deposited on the surface of the base fabric between the activated carbon fibres in the layer of flocked activated carbon fibres.

[0080] The layered material of the invention does not require additional activated carbon material to exhibit excellent adsorption capacity and filtration performance. Where a material comprises activated carbon powder between the flocked activated carbon fibres in the layer of flocked activated carbon fibres, the base fabric material properties are compromised; flexibility ordrapability is reduced, and the breathability of the layered material is also compromised. Furthermore, where a material comprises activated carbon powder between flocked activated carbon fibres in the layer of flocked activated carbon fibres, that activated carbon powder is not fixed in place and can re-distribute over the surface of the base material or be lost entirely. If that activated carbon powder is relied upon for adsorption capacity, then the adsorption capacity of the material is at the very least compromised and uncontrolled or non-uniform, and at the worst it is lost altogether.

[0081] The use of flocked activated carbon fibres alone as the adsorbing component also significantly reduces the complexity and cost of manufacture.

[0082] Flocking at the densities described herein can obviate the need for further activated carbon deposition(s) to achieve the desired protective properties.

[0083] In some embodiments of the invention, the average fibre length of the activated carbon fibres is 0.10 to 5.0 mm, 0.25 to 3.0 mm, 0.50 to 2.0 mm, 1.0 to 1.5 mm.

[0084] Where the average fibre length of the activated carbon fibres is towards the upper end of a range, for example when the average fibre length of the activated carbon fibres is 5.0 mm, or 3.0 mm, or 2.0 mm, or 1.5 mm, then the adsorption capacity of the layer of flocked activated carbon fibres is increased, because the activated carbon weight and carbon depth of the layered material is increased. For fibres of increased length there is an increased adsorption time for agents which impinge on the layered material. This increases the likelihood that an agent will be adsorbed by the layer of flocked activated carbon fibres.

[0085] By contrast, when the average fibre length of the activated carbon fibres is towards the lower end of a range, for example when the average fibre length of the activated carbon fibres is 0.10 mm, or 0.25 mm, or 0.50 mm, or 1.0 mm, the total weight of the layered material is reduced but the layered material retains an adsorption capacity that is suitable for the intended use. The layered material may be more comfortable for a user or more practical to use and transport. When the average fibre length of the activated carbon fibres is towards the lower end of a range, the cost of producing the layered material is also reduced.

[0086] In some embodiments of the invention, the activated carbon fibres are substantially the same length. In some embodiments, the activated carbon fibres are about the same length. When the activated carbon fibres are substantially the same length or about the same length, the uniformity of carbon depth is008915449

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[0088] increased across the layered material, resulting in substantially uniform adsorption properties over the layered material.

[0089] In some embodiments, the activated carbon fibres have lengths ranging from 0.08 mm to 0.12 mm. In some embodiments, the activated carbon fibres have lengths ranging from 0.4 mm to 0.6 mm. In some embodiments, the activated carbon fibres have lengths ranging from 0.8 mm to 1.2 mm. In some embodiments, the activated carbon fibres have lengths ranging from 1.6 mm to 2.4 mm. In some embodiments, the activated carbon fibres have lengths ranging from 2.8 mm to 4.2 mm. In some embodiments, the activated carbon fibres have lengths ranging from 4 mm to 6 mm. When the activated carbon fibres have lengths within one of these ranges, the uniformity of carbon depth is increased across the layered material, resulting in substantially uniform adsorption properties over the layered material. In some embodiments, the minimum fibre length of the activated carbon fibres is no more than 5%, 10% or 20% less than the average fibre length. In some embodiments, the maximum fibre length of the activated carbon fibres is no more than 5%, 10% or 20% greater than the average fibre length. When the activated carbon fibres satisfy these ranges, the uniformity of carbon depth is increased across the layered material, resulting in substantially uniform adsorption properties over the layered material.

[0090] In some embodiments, the carbon depth is substantially uniform over the surface of the layered material. In some embodiments of the invention, the layered material additionally comprises a protective fabric layer (b), arranged so that the layer of flocked activated carbon fibres is between the base fabric layer (a) and the protective fabric layer (b).

[0091] The presence of an additional protective fabric layer (b) provides at least two advantages. First, it provides an additional barrier before harmful agents reach the layer of flocked activated carbon fibres. Agents may be completely prevented from penetrating the material before they even reach the layer of flocked activated carbon fibres, and the passage of other agents may be slowed such that it is more likely that the layer of flocked activated carbon can effectively adsorb them. Second, a protective fabric layer (b) also provides protection to the layer of flocked activated carbon fibres such that they are less likely to degrade, or such that impacts to the material are less likely to remove some of the flocked activated carbon fibres.

[0092] In some embodiments of the invention comprising a protective fabric layer (b), the protective fabric layer (b) is impregnated with activated carbon.

[0093] By impregnating the protective fabric material (b) with activated carbon, the adsorption capacity and filtration performance of the layered material is enhanced. There is a first opportunity for the layered material to adsorb agents before they reach the layer of flocked activated carbon fibres. The impregnation of the protective fabric (b) does not compromise the handle, flexibility or drapability or other desirable attributes of the layered material, and the impregnated activated carbon is fixed within the fabric; it is not susceptible to redistribution in the material or loss from the material. The activated carbon that is used to impregnate the protective fabric layer (b) may be in the form of activated carbon fibres, or may be in a different form (such as activated carbon powder or spherical activated carbon). Where the008915449

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[0095] activated carbon that is impregnated in the protective fabric layer (b) is of a different form to the flocked activated carbon layer or the base fabric layer (a), each type may be optimised for the adsorption of different agents.

[0096] Methods to form an impregnated base fabric material are known in the art. In a typical method, an aqueous slurry of a fine particle activated carbon powder is formed, to which a synthetic latex is added. A base fabric material may then be impregnated with the resultant slurry comprising latex, before drying and curing. A typical method of impregnation is a process known as paddling, in which a base fabric material is passed through a trough containing the slurry, before being passed through a mangle to squeeze out any excess. Drying can be achieved by various means, including by steam cans or by hot air drier, and this step may also act to cure the material.

[0097] In some embodiments of the invention comprising a protective fabric layer (b), a fibre end that is not adhered to the base fabric layer (a) is adhered to the protective fabric layer (b). Where an activated carbon fibre in the layer of flocked activated carbon fibres is adhered at one end to the base fabric layer (a) and at the other end to the protective fabric layer (b), this contributes to improved strength of the layered material and a reduced likelihood that the flocked activated carbon fibres will redistribute. It also allows for the fibres to be maintained in position relative to one another. For example, the flocked activated carbon fibres may be maintained in a position that is substantially perpendicular with respect to the base fabric layer (a) and the protective fabric layer (b). By ensuring that the activated carbon fibres are fixed in a pre-determined position, the carbon depth of the layered material is maintained over the entire surface, making performance uniform over the entire surface. A substantially perpendicular arrangement of the flocked activated carbon fibres with respect to the base fabric (a) and the protective fabric (b) may be most desirable for the maximisation of carbon depth for a particular activated carbon weight of the layered material.

[0098] In some embodiments, each activated carbon fibre is adhered at a fibre end to the protective fabric layer (b) via an adhesive. The adhesive may be based on an aqueous binder system including, but not limited to, acrylic, vinyl acetate ethylene (VAE), or polyurethane dispersion (PUD). The adhesive may be a hot melt (thermoplastic) adhesive.

[0099] The invention further provides a process to produce the layered material of the invention, wherein the process comprises:

[0100] (A) applying an adhesive to a base fabric layer (a);

[0101] (B) applying activated carbon fibres to the adhesive on the base fabric layer (a), such that each activated carbon fibre is adhered at a fibre end to the base fabric layer (a), to form a layer of flocked activated carbon fibres, optionally wherein:

[0102] (i) the base fabric layer (a) is curved and the activated carbon fibres are applied to a convex face of the curved base fabric layer (a); and / or

[0103] (ii) the base fabric layer (a) is stretched and the activated carbon fibres are applied to a stretched surface of the base fabric layer (a);

[0104] and008915449

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[0106] (C) curing the adhesive.

[0107] The adhesive that is applied to the base fabric layer (a) may be based on an aqueous binder system including, but not limited to, acrylic, vinyl acetate ethylene (VAE), or polyurethane dispersion (PUD). The adhesive may be a hot melt (thermoplastic) adhesive. Application methods of the adhesive may include, but are not limited to, foam, print, engraved roller or hot melt and spray.

[0108] Step (B), comprising the application of the activated carbon fibres to the base fabric layer (a), is a flocking step. The activated carbon fibres may be applied to the adhesive on the base fabric layer (a) by any conventional flocking method preferably prior to the curing of the adhesive. In a mechanical flocking method, the activated carbon fibres may be deposited on the adhesive by means of a hopper and the assembly may be vibrated by means of a beater bar to orient the activated carbon fibres such that they are substantially perpendicular to the base fabric layer (a). Excess activated carbon fibres may be removed by vacuum.

[0109] In an electrostatic flocking method, an electrostatic charge is generated on the activated carbon fibres which propels the activated carbon fibres on to the grounded base fabric layer (a) that is coated with adhesive. The fibres penetrate and imbed into the adhesive, substantially perpendicularly to the base fabric layer (a).

[0110] In both mechanical and electrostatic methods, the adhesive may be cured by a method that is suitable for the adhesive, for example, by air drying, by heating or by cooling.

[0111] In some embodiments, the base fabric layer (a) may be manipulated into a curved shape prior to flocking. Where the surface of the base fabric layer (a) has curvature, the activated carbon fibres may be applied to a convex face of the base fabric layer (a), which allows for a high density of fibre ends that are adhered to the base fabric layer (a) and therefore an increased activated carbon weight of the layered material, for improved adsorption and filtration performance. Once flocking is complete, the fabric can be returned to a substantially flat shape. The fibre density is higher than can be achieved when flocking on a flat substrate. Varying the degree of curvature in the flocking step is one method by which the density of flocked fibres and the activated carbon weight of the layered material can be controlled. A base fabric layer (a) which comprises a knitted material is particularly advantageous in this process, because it easily drapes to form a curved surface, unlike a more structured woven or nonwoven fabric.

[0112] In some embodiments, the base fabric layer (a) may be stretched prior to flocking. This allows for a high density of fibre ends that are adhered to the base fabric layer (a) and therefore an increased activated carbon weight of the layered material, for improved adsorption and filtration performance. Once flocking is complete, the fabric can be returned to a non-stretched state. The fibre density is higher than can be achieved when flocking on a non-stretched substrate. Varying the degree of stretch in the flocking step is one method by which the density of flocked fibres and the activated carbon weight of the layered material can be controlled. A base fabric layer (a) which comprises a knitted fabric is particularly advantageous in this process, because knitted fabrics may be easily stretched in both length and width directions to maximise the density of fibres.008915449

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[0114] In some embodiments, the base fabric layer (a) is both stretched and curved prior to flocking. When the base fabric (a) is both stretched and curved for flocking, the achieved fibre density may be very high. In some embodiments, the process additionally comprises a step in which a protective fabric layer (b) is applied to the layer of flocked activated carbon fibres. The presence of an additional protective fabric layer (b) provides at least two advantages. First, it provides an additional barrier before challenge agents meet the layer of flocked activated carbon fibres. Agents may be completely prevented from penetrating the material before they even reach the layer of flocked activated carbon fibres, and the passage of other agents may be slowed such that it is more likely that the layer of flocked activated carbon can effectively adsorb them. Second, a protective fabric layer (b) also provides protection to the layer of flocked activated carbon fibres such that they are less likely to degrade, or such that impacts to the material are less likely to remove some of the flocked activated carbon fibres.

[0115] In some embodiments, a layer of adhesive is applied to the protective fabric layer (b) before application to the layer of flocked activated carbon fibres, such that after the application the layer of adhesive is between the protective layer (b) and the layer of flocked activated carbon fibres.

[0116] The adhesive may be based on an aqueous binder system including, but not limited to, acrylic, vinyl acetate ethylene (VAE), or polyurethane dispersion (PUD). The adhesive may be a hot melt (thermoplastic) adhesive. It may be applied by any suitable method including, but not limited to, foam, print, engraved roller or hot melt and spray. This allows for a fibre end that is not adhered to the base fabric (a) to be adhered to the protective fabric layer (b). This contributes to improved strength of the layered material and a reduced likelihood that the flocked activated carbon fibres will redistribute. It also allows for the fibres to be maintained in position relative to one another. For example, the flocked activated carbon fibres may be maintained in a position that is substantially perpendicular with respect to the base fabric layer (a) and the protective fabric layer (b). By ensuring that the activated carbon fibres are fixed in a pre-determined position, the carbon depth of the layered material is maintained over the entire surface, making performance uniform over the entire surface. A substantially perpendicular arrangement of the flocked activated carbon fibres with respect to the base fabric (a) and the protective fabric (b) may be most desirable for the maximisation of carbon depth for a particular activated carbon weight of the layered material.

[0117] The invention further provides a garment comprising the layered material as described in any previous embodiment. A garment comprising the layered material of the invention is useful for the protection of users against chemical, biological, radiological and nuclear (CBRN) materials and agents; the protection of users against carcinogenic fire effluents; and the protection of First Responders, such as firefighters, paramedics, and police officers, or military personnel, construction workers, workers in incineration plants. A garment comprising the layered material of the invention exhibits excellent adsorption and filtration properties without compromising material flexibility and handle. When a garment comprises the layered material of the invention, there is a reduced requirement for additional layers; the layered material itself is comfortable next to the skin and exhibits excellent adsorption and filtration performance. Because008915449

[0118] 14

[0119] further layers are not required, the garment may have significantly reduced weight and increased comfort compared to a garment comprising an alternative activated carbon material.

[0120] The features disclosed in the foregoing description, or in the following claims, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0121] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0122] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0123] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0124] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0125] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / - 10%.

Claims

00891544915Claims:

1. A layered material, comprising:i. a base fabric layer (a);ii. activated carbon fibres, each activated carbon fibre being adhered at a fibre end to one side of the base fabric (a) to form a layer of flocked activated carbon fibres;wherein an activated carbon weight of the layered material is 50 gsm to 200 gsm.

2. The layered material according to claim 1 , wherein the activated carbon weight of the layered material is 80 gsm to 150 gsm, or 100 gsm to 120 gsm.

3. The layered material according to claim 1 or claim 2, wherein the base fabric layer (a) comprises a knitted fabric.

4. The layered material according to any of claims 1 to 3, wherein the base fabric layer (a) is impregnated with activated carbon.

5. The layered material according to any of claims 1 to 4, wherein there is no activated carbon powder deposited on the surface of the base fabric between the activated carbon fibres in the layer of flocked activated carbon fibres.

6. The layered material according to any of claims 1 to 5, wherein the average fibre length of the activated carbon fibres is 0.10 to 5.0 mm, optionally wherein the average fibre length is 0.25 to 3.0 mm.

7. The layered material according to any of claims 1 to 6, wherein the activated carbon fibres are substantially the same length.

8. The layered material according to any of claims 1 to 7, wherein the layered material additionally comprises a protective layer (b), arranged so that the layer of flocked activated carbon fibres is between the base fabric layer (a) and the protective fabric layer (b).

9. The layered material according to claim 8, wherein the protective fabric layer (b) is impregnated with activated carbon.

10. The layered material according to claim 8 or claim 9, wherein a fibre end that is not adhered to the base fabric (a) is adhered to the protective fabric layer (b).

11. A process to produce a layered material, wherein the process comprises:(A) applying an adhesive to a base fabric layer (a);00891544916(B) applying activated carbon fibres to the adhesive on the base fabric layer (a), such that each activated carbon fibre is adhered at a fibre end to the base fabric layer (a) to form a layer of flocked activated carbon fibres, optionally wherein:(i) the base fabric layer (a) is curved and the activated carbon fibres are applied to a convex face of the curved base fabric layer (a); and / or(ii) the base fabric layer (a) is stretched and the activated carbon fibres are applied to a stretched surface of the base fabric layer (a);and(C) curing the adhesive.

12. The process of claim 11 , additionally comprising a step (D) in which a protective fabric layer (b) is applied to the layer of flocked activated carbon fibres.

13. The process of claim 12, wherein a layer of adhesive is applied to the protective fabric layer (b) before application to the layer of flocked activated carbon fibres, such that after the application, the layer of adhesive is between the protective layer (b) and the layer of flocked activated carbon fibres.

14. A garment comprising the layered material of any one of claims 1 to 10.

15. A garment comprising the product of the process of any of claims 11-13.