WO2007107721A1

WO2007107721A1 - Air permeable, liquid impermeable barrier structure for protective garments

Info

Publication number: WO2007107721A1
Application number: PCT/GB2007/000946
Authority: WO
Inventors: Robert Fulford; Stanley Russell
Original assignee: Remploy Limited
Priority date: 2006-03-17
Filing date: 2007-03-16
Publication date: 2007-09-27
Also published as: GB0605335D0

Abstract

A barrier structure which may be used in a gas-tight protective suit has an adsorption structure (2) and a membrane (5) attached to the adsorption structure (2). The adsorption structure has a layer of activated carbon (3) which may comprise particles bonded to a textile carrier (4). The membrane (5) is a liquid proof gas and vapour permeable polymeric membrane formed from an intrinsically permeable hydrophilic polymeric material such as a block copolymer with hard segmental nodes linked by a web of fibrils defining small molecular pores.

Description

AIR PERMEABLE, LIQUID IMPERMEABLE BARRIER STRUCTURE FOR PROTECTIVE GARMENTS

This invention relates to a barrier structure particularly for protective garments which may be of the so-called NBC (Nuclear, Biological and Chemical resistant) or CBRN (Chemical, Biological, Radiation and Nuclear resistant) kind. NBC or CBRN suits are worn by personnel engaged in hazardous duties or tasks, such as military or defence forces, fire brigade, police, medical and rescue personnel.

The principal requirement of such suits is to prevent noxious substances coming into contact with the wearer's skin. Known such suits include gas tight suits made from air and water vapour impervious materials such as polyurethane or rubber sheeting. Such suits can provide an effective barrier against noxious substances. However, they prevent escape of air and moisture from within the suit which can cause discomfort or even personal danger to the wearer, especially in hot environments, and this imposes a serious limitation on their use.

It is also known to use air and water vapour permeable suits which contain an activated carbon layer. Air and water vapour can escape from within the suit whilst ingress of noxious substances is restricted by the activated carbon which adsorbs such substances and prevents through-transmission to the wearer's skin. The activated carbon layer may comprise carbon particles e.g. as described in

U.S. 4857243, or carbon beads e.g. as described in U.S. 2004/0038802A, and the carbon materials may be bonded to a textile fabric carrier.

U.S. 4457345 describes the use of fabrics made with activated carbon fibres. U.S. 2005/0252379A describes the use of a layer of activated carbon fibre which is spot-bonded to a textile fabric carrier and which may be used in combination with a pervious polymeric membrane.

Pervious membranes or coatings are well known in the case where escape of air and water vapour is required in a waterproof structure. In particular, it is well known to use porous polytetrafluoroethylene coatings, made by stretching polymer sheets to cause the sheets to rupture and form small holes or pores, such as the coating material sold as Gortex®, e.g. as described in U.S. 3953566. Such coatings can ensure high levels of comfort but do not reliably have a high level of resistance to penetration by noxious substances. The requirement of breathability and comfort with effective protection against ingress of noxious substances is difficult to achieve.

An object of the present invention is to provide a barrier structure which has good breathability yet which can afford effective protection against ingress of noxious substances. The invention is based on the realisation that the use of an activated carbon layer in conjunction with a non-porous or liquid proof gas and vapour permeable polymeric membrane of the intrinsically permeable hydrophilic kind can give significant benefits.

Thus, and in accordance with the present invention there is provided a barrier structure comprising an adsorption structure having at least one porous activated carbon layer, and at least one membrane applied to the adsorption structure, which membrane is a liquid proof gas and vapour permeable polymeric membrane formed from an intrinsically permeable hydrophilic polymeric material.

With this arrangement the membrane can allow breathability in a carefully controlled manner i.e. such as to permit adequate rates of escape of air and water vapour whilst effectively preventing ingress of noxious substances. Also, polymeric materials of the hydrophilic intrinsically permeable kind are conducive to manufacture of soft, flexible membranes. Accordingly, when used to make a protective suit or other garment, the barrier structure of the invention can ensure good wearer comfort and safety without compromising protection against noxious substances.

The polymeric material may be as described in GB 2087909A and GB 2157703 A. Thus the material may be a polyurethane block copolymer having hard and soft segments made by reaction of a polyisocyanate polyol, and a lower molecular weight component having active hydrogens such as a polyol, a polyamide, a polyhydrazide.

The resulting material typically has a non-porometric polymeric structure with hard segmental nodes linked by a web of fibrils defining small molecular pores therebetween. No destructive mechanical treatment, such as stretching is necessary to produce pores or holes by rupturing of the membrane whereby it can be ensured that all pores are small molecular pores rather than larger structural holes.

Reference is made to GB 2087909A and GB 2157703 A for further description of suitable polymeric materials. The activated carbon layer may provide a high surface activated carbon using known techniques, as mentioned above and thus may comprise carbon particles which may be microparticles or larger beads and which may be bonded or otherwise applied to a porous textile or other carrier sheet or layer, and/or carbon fibres incorporated into a cloth (referred to as carbon cloth or charcoal cloth) which cloth may be a knitted, woven or non- woven structure or any combination of these structures formed wholly from the carbon fibres or from a mixture of the fibres with any other fibres.

There may be one activated carbon layer which, as appropriate, may be assembled with one carrier sheet or layer. Alternatively multiple such layers may be assembled in any combination to give a laminated said adsorption structure with the layers merely in juxtaposition and/or attached or held in position relative to each other in any suitable manner using bonding, stitching, interweaving, enclosure or the like. The overriding requirement is that the adsorption structure should be freely porous so as to allow ready flow therethrough of air and water vapour whilst presenting a high activated carbon surface area to ensure adsorptive contact with noxious substances which may be contained in air or gas or vapour or liquid whether in solid or dissolved or colloidal or suspended form.

The (or each) said non-porous membrane may be applied to the activated carbon adsorption structure by close juxtaposition thereto and/or by attachment or retention relative to the adsorption structure in any suitable manner. Preferably the membrane is attached to the adsorption structure by bonding e.g. using a foam, hot melt, hot melt dot, powder, web, net, transfer or direct coating technique. Most preferably the bonding technique is not such as to obscure unduly the permitted permeability of the barrier structure or the membrane and thus a porous adhesive layer and/or application of adhesive to selected regions only of the membrane may be used.

There may be a single membrane and this may be applied to one outer surface of the adsorption structure, particularly a surface thereof intended to be directed outwardly. Alternatively however, multiple membranes may be used, on both outer faces of the adsorption structure and/or internally thereof e.g. between layers where the adsorption structure is laminated.

The barrier structure may be used in conjunction with additional layers applied to one or both outer faces thereof.

Thus, for example there may be a layer applied to or simply held or used loosely in juxtaposition relative to that outer surface which is intended to be directed outwardly, which layer may be a porous material, such as a fabric, chemically treated with a resistant substance, or formed from a material such as aramid fibres, such as Kevlar® or Nomex®, which gives strength and is intrinsically resistant to extreme adverse influences. Also there may be a layer applied to or simply held or used loosely in juxtaposition relative to that outer surface of the barrier structure which is intended to be directed inwardly, which layer may be a high comfort wicking fabric which minimises retention of moisture and facilitates escape of such moisture as water vapour with warm air through the barrier structure outwardly thereof. The barrier structure may also be used with one or more added layers which incorporate other protective substances or structures, and/or the materials of the barrier structure may incorporate such substances or structures, for any desired further purpose as appropriate.

In particular, metallic substances may be incorporated for purposes such as heat reflection and lowering of the thermal image, as described in DE 10224860.

Conveniently such substances may be incorporated in the (or each) membrane during manufacture thereof.

The barrier structure of the invention, alone or in combination with one or more further layers as mentioned above may be used to manufacture any suitable garment, shelter, cover or the like for protecting against exposure of a person's skin to noxious substances.

The barrier structure is particularly useful for manufacture of a protective suit in which case to ensure that the entire suit is gas tight to a required level cut panels of the barrier structure may be assembled together via gas tight seams made by sewing and taping edges of the membrane and/or by heat welding or ultrasonic welding of adjacent membrane edges using seam free technology.

The invention will now be described further by way of example only and with reference to the accompanying drawings in which:- Figure 1 is a diagrammatic sectional view through one form of a garment made with a protective barrier in accordance with the present invention; and Figure 2 is an enlarged detail of a membrane forming part of the protective barrier of Figure 1.

Referring to the drawings, Figure 1 shows a section through a protective suit to be worn by a person to give NBC or CBRN protection.

The suit has a central protective barrier 1 made from flexible panels which are joined at edges to form the suit which defines a sealed enclosure around some or all of the wearer's body.

The protective barrier 1 has a central adsorption structure 2 which has a layer of activated carbon 3 which may be self supporting or may be bonded to a carrier layer 4 such as a textile cloth.

The activated carbon 3 may be particulate or may be formed from carbon fibres as hereinbefore described.

The adsorption structure is porous and permits ready flow therethrough of gas, air, liquid, vapour, in intimate contact with the relatively large surface area of the activated carbon material.

At that outer side of the protective barrier 1 which in use faces outwardly, i.e. away from the wearer's body, a membrane 5 is bonded to the outer surface of the adsorption structure 2. Spot bonding or similar technique is used to ensure that the membrane 5 and the adsorption structure 2 are not unduly obstructed by the adhesive.

The membrane 5 is a thin polyurethane sheet formed in the manner described in GB 2087909A or GB 2157703 A as mentioned above. This sheet allows passage therethrough of air and water vapour but is otherwise non-porous i.e. it does not allow passage therethrough of larger molecules. It is gas tight so far as such larger molecules are concerned.

The membrane has these properties intrinsically as a consequence of its molecular structure as shown in Figure 2. That is, the polyurethane material has solid nodes linked by fibrils. This also gives softness and flexibility to the sheet. The membrane may incorporate one or more metal ions as described in

DE 10224860.

The panels of the protective barrier 2 are assembled edge to edge with gas tight joins which may be taped seams or welds.

The protective barrier 2 in assembled form is worn over a separate wicking, internal suit or inner garment 6 made from synthetic fibres which channel body moisture and hot air away from the person's body to the protective barrier from where it can escape to its outwardly directed surface.

An outer porous protective suit 7 is worn on top of the protective barrier 1 to give protection against adverse influences whilst allowing escape of body moisture and hot air.

This outer protective suit 7 may be made from a strong, chemical resistant fibre such as Kevlar® or Nomex®.

With the suit described above effective protection can be afforded against noxious substances. Large molecules can be effectively prevented from passing through the membrane 5. Anything noxious which in fact does pass through is adsorbed by the adsorption structure and safely retained. Hot air from the wearer's body can readily escape to the external environment through the membrane 5.

This escape of air and water vapour together with the natural softness and flexibility of the membrane ensure that the suit can be worn safely and comfortably.

It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiment, which are described by way of example only.

Claims

1. A barrier structure comprising an adsorption structure (1) having at least one porous activated carbon layer (3), and at least one membrane (5) applied to the adsorption structure, characterised in that the membrane is a liquid proof gas and vapour permeable polymeric membrane formed from an intrinsically permeable hydrophilic polymeric material.

2. A barrier structure according to claim 1 characterised in that the polymeric material is a polyurethane block copolymer.

3. A barrier structure according to claim 2 characterised in that the block copolymer has hard and soft segments made by reaction of a polyisocyanate polyol and a lower molecular weight component having active hydrogens.

4. A barrier structure according to any one of claims 1-3 characterised in that the polymeric material has a non-porometric polymeric structure with hard segmental nodes linked by a web of fibrils defining small molecular pores therebetween.

5. A barrier structure according to any one of claims 1 to 4 characterised in that the activated carbon layer (3) comprises carbon particles applied to a carrier sheet (4).

6. A barrier structure according to any one of claims 1 to 5 characterised in that the activated carbon layer (3) comprises carbon particles and/or carbon fibres incorporated into a cloth.

7. A barrier structure according to any one of claims 1 to 6 characterised in that the (or each) membrane (5) is attached to the adsorption structure (1).

8. A barrier structure according to claim 7 characterised in that the (or each) membrane (5) is bonded to the adsorption structure (1) with a porous adhesive layer.

9. A barrier structure according to claim 7 characterised in that the (or each) membrane (5) is bonded to the adsorption structure by application of adhesive to selected regions only of the (or each) membrane (5).

10. A barrier structure according to any one of claims 1 to 9 characterised in that an additional layer (7) is applied to an outer face of the structure, said outer additional layer comprising a porous fabric.

11. A barrier structure according to claim 10 characterised in that the porous fabric is formed from aramid fibres.

12. A barrier structure according to any one of claims 1 to 12 characterised hi that an additional layer (6) is applied to an inner face of the structure, said inner additional layer comprising a wicking fabric.

13. A barrier structure according to any one of claims 1 to 12 characterised by incorporation of a metallic substance.

14. A barrier structure according to claim 13 characterised in that the metallic substance is incorporated in the (or each) membrane (5).

15. A garment made with a barrier structure according to any one of claims 1 to 14.

16. A garment according to claim 15 which is a gas-tight protective suit characterised in that panels of the barrier structure are assembled together via gas-tight seams.