EP3582859B1

EP3582859B1 - Fire resistant textile

Info

Publication number: EP3582859B1
Application number: EP18705485.3A
Authority: EP
Inventors: Robert Wesley BEADLE
Original assignee: Arville Textiles Ltd
Current assignee: Arville Textiles Ltd
Priority date: 2017-02-17
Filing date: 2018-02-12
Publication date: 2021-01-13
Anticipated expiration: 2038-02-12
Also published as: AU2018220789A1; GB201702606D0; ES2857824T3; WO2018150165A1; EP3582859A1; GB2559772A; AU2018220789B2

Description

The present invention relates to fire resistant textile materials and to garments manufactured from such materials. In particular, but not exclusively, the present invention relates to articles of fire resistant clothing for use by fire fighters, military personnel and police officers, or the like, and to textiles for manufacturing such clothing.
The flammability regulations of the European Union and the USA effectively form the basis for many national regulatory bodies throughout the world. The European Personal Protective Equipment (PPE) Directives, which have been obligatory since the mid-1990s, have led to the development and use of a wide range of European (EN) specifications for PPE. CEN, the European Standardisation body, has developed several product specifications published as EN standards that set out specific methods of tests and related performance levels for clothing, such as EN 469. Although the application of the two European PPE directives, one for CE certification of products and the other for product use, are mandatory, it is not mandatory to use EN product specifications for CE certification. However, almost all fire protective clothing in use in Europe is CE certified using EN standards because this is the most straightforward route and therefore understood best by both the PPE manufacturers and their clients.
Clothing for protection against heat and flame must pass these minimum performance requirements for flame, radiant heat, heat resistance, tensile and tear strength, and penetration by water and liquid chemicals. The assembled garments, which typically include a pair of trousers/salopettes and a jacket, must protect the wearer from radiant and thermal exposure, and unexpected flashover conditions, whilst still maintaining an adequate level of dexterity and comfort.
As described in WO2015/008030 , it is known to reduce second and third degree burns to a wearer by ensuring the barrier of protective clothing located between the heat source and the wearer's skin remains intact during exposure to heat and flame whilst ensuring an air gap exists between the skin and the heat source. It is also known to provide a single woven layer of fire resistant textile material which utilises the strength characteristics of meta-aramid fibres in a warp yarn and the moisture management properties of wool in a blended wool and cellulose weft yarn for direct contact against a wearer's skin. A known fire resistant textile material is described in CA2228443A1 .
However, conventional fire resistant textile materials are relatively heavy and do not sufficiently and efficiently move moisture in the form of sweat away from the skin which can otherwise result in steam/scald burns. Furthermore, the demand for fire resistant garments which are lighter in terms of weight and with improved comfort, breathability and moisture management is ever increasing.
It is an aim of certain embodiments of the present invention to provide a fire resistant textile material which is lightweight, breathable and comfortable.
It is an aim of certain embodiments of the present invention to provide a fire resistant textile material which has an open structure and which reacts to the environment.
It is an aim of certain embodiments of the present invention to provide a fire resistant textile material which efficiently moves moisture away from a wearer's skin to reduce the risk of scald burns.
It is an aim of certain embodiments of the present invention to provide a fire resistant textile material which meets the required standards of the key flammability regulations, such as EN 469, and has a fabric weight of around 250gsm and desirably less than 500gsm when combined with a moisture barrier and inner liner for a firefighting garment.
According to a first aspect of the present invention there is provided a fire resistant textile material comprising:

an outer woven layer comprising polyparaphenylene isophthalamide (meta-aramid) fibres or a blend of meta-aramid with polyparaphenylene terephthalamide (para-aramid) fibres;
an inner woven layer comprising polyparaphenylene terephthalamide (para-aramide) fibres; and
characterised in that the material further comprises an intermediate woven layer disposed between the outer and the inner woven layers and comprising a blend of wool fibres and cellulose fibres.

Optionally, the intermediate woven layer comprises a twill weave defining an open structure.
Optionally, the twill weave comprises a 2 x 2 twill weave.
Optionally, the wool fibres have a thickness of around 15.5µm to around 29.5µm.
Optionally, the wool fibres are shrink resistant wool fibres.
Optionally, the blend of wool fibres and cellulose fibres comprises by weight from around 25% wool and 75% cellulose to around 75% wool and 25% cellulose.
Optionally, the blend of wool fibres and cellulose fibres comprises by weight around 55% wool and around 45% cellulose.
Optionally, the cellulose fibres comprise a fire retardant viscose fibre.
Optionally, the outer woven layer comprises a twill weave defining an open structure in normal use.
Optionally, the twill weave comprises a 2 x 2 twill weave.
Optionally, the inner woven layer comprises a twill weave defining an open structure.
Optionally, the twill weave comprises a 2 x 2 twill weave.
Optionally, the outer woven layer comprises a yarn count of from around 40/2 Nm (500 dtex) to around 100/2 Nm (200 dtex).
Optionally, the yarn count of the outer woven layer is around 72/2 Nm (277 dtex).
Optionally, the inner woven layer comprises a yarn count of from around 50/1 Nm (200 dtex) to around 100/2 Nm (200 dtex).
Optionally, the yarn count of the inner woven layer is around 100/2 Nm (200 dtex).
Optionally, the intermediate woven layer comprises a yarn count of from around 20/2 Nm (1000 dtex) to around 100/2 Nm (200 dtex).
Optionally, the yarn count of the intermediate woven layer is around 60/2 Nm (333 dtex).
Optionally, the outer woven layer comprises around 93% meta-aramid, around 5% para-aramid, and around 2% antistatic fibre.
Optionally, the outer woven layer comprises Nomex™.
Optionally, the inner woven layer comprises 100% para-aramid.
Optionally, the inner woven layer comprises Kevlar™.
Optionally, the inner woven layer is connected to the intermediate woven layer and the outer woven layer.
Optionally, warp ends from the inner woven layer weave into the outer woven layer and the intermediate woven layer respectively by crossing over individual picks thereof.
Optionally, the warp ends of the inner layer interact with the picks of the outer layer and intermediate layer as illustrated in Figure 2.
Optionally, the material has a weight of around 250gsm.
According to a second aspect of the present invention there is provided a use of a fire resistant textile material in accordance with the first aspect of the present invention to protect a human's or animal's skin from burning.
According to a third aspect of the present invention there is provided a garment comprising a fire resistant textile material in accordance with the first aspect of the present invention.
Optionally, a face surface of the outer layer defines an outer surface of the garment and a back face of the inner layer is contactable with a wearer's skin or an inner membrane layer of the garment.
Optionally, the fire resistant textile material has a weaving plan substantially as shown in Figure 3.
According to a fourth aspect of the present invention there is provided a method of manufacturing a fire resistant textile material, comprising:

providing an outer woven layer comprising polyparaphenylene isophthalamide (meta-aramid) fibres or a blend of meta-aramid with polyparaphenylene terephthalamide (para-aramid) fibres;
providing an inner woven layer comprising polyparaphenylene terephthalamide (para-aramide) fibres; and
characterised in that the method further comprises providing an intermediate woven layer between the inner and outer woven layers, wherein the intermediate woven layer comprises a blend of wool fibres and cellulose fibres.

Optionally, the outer and inner woven layers define opposed face and back surfaces of the material respectively.
Optionally, the method further comprises connecting yarns of the inner woven layer with yarns of the intermediate woven layer and the outer woven layer.
Optionally, connecting comprises interweaving warp ends from the inner layer into the outer layer and the intermediate layer respectively by crossing over individual picks thereof.
Optionally, the method further comprises interacting the warp ends of the inner layer with the picks of the outer layer and intermediate layer as illustrated in Figure 2.
Optionally, the intermediate woven layer and the inner woven layer each comprise a twill weave to define a substantially open structure.
Optionally, the outer woven layer comprises a twill weave defining a substantially open structure in normal use.

Description of the Drawings

Certain embodiments of the present invention will now be described with reference to the accompanying drawings in which:

Figure 1a illustrates an isometric view from the back side of a portion of a textile material in accordance with certain embodiments of the present invention;
Figure 1b illustrates a plan view from the face side of the textile material of Figure 1a;
Figure 1c illustrates a sectional view through the textile material of Figures 1a and 1b;
Figure 2 illustrates a lifting plan for manufacturing a textile according to certain embodiments of the present invention;
Figure 3 illustrates a weaving plan for manufacturing a textile according to certain embodiments of the present invention; and
Figures 4a and 4b illustrate how the outer layer of the textile according to certain embodiments of the present invention reacts in a high temperature environment.

Detailed Description

As illustrated in Figures 1a to 1c, a fire resistant textile material 100 includes three woven layers 102,104,106 which are distinct from each other and adapted to perform a particular technical function.
The outer woven layer 102 which aptly provides a face surface of the textile material 100 comprises a meta-aramid yarn. Aptly, the meta-aramid yarn is a polyparaphenylene isophthalamide (meta-aramid) yarn, such as Nomex™. The yarn optionally includes around 50-100% meta-aramid and around 0-50% para-aramid, and aptly comprises 93% meta-aramid (e.g. Nomex™), around 5% para-aramid (e.g. Kevlar™), and around 2% antistatic fibres (e.g. carbon fibres). Alternative fibres for the outer woven layer 102 may comprise para-aramids, polybenzimidazole (PBI), poly (paraphenylenbenzobisoxazole) (PBO), or blends thereof. The outer layer 102 is a 2x2 twill weave but other suitable weave patterns may be used such as a plain weave, 3x1, 4x1 or 2x2 twill weaves, ripstop or hopsack weaves, satin, or sateen weaves, or the like. A 2x2 twill weave is desirable in the outer layer to hide the stitching points of the lower layers. A twill weave also desirably provides a tighter, denser construction which enhances the dimensional stability and increases durability after multiple washing. Nomex™ yarn is typically available in three types based on the linear mass density (2.2 dtex, 1.7dtex and 1.4dtex). Aptly, a 1.4dtex Nomex™ yarn is used as it offers desirable comfort and flexibility in view of its fineness. A yarn count of the outer layer 102 is from around 40/2 Nm (500 dtex) to around 100/2 Nm (200 dtex), and aptly around 72/2 Nm (277 dtex).
The intermediate woven layer 104 comprises a blended yarn of wool and cellulose-based (e.g. Lenzing™) fibres. The blended yarn optionally comprises by weight from around 25% wool and 75% cellulose to around 75% wool and 25% cellulose fibres, and aptly around 55% wool to around 45% cellulose fibres for optimum moisture management as described further below. The wool fibres have a thickness of between around 15.5-29.5µm, and aptly around 20.8 µm which has been found to be optimum in terms of efficient and effective transportation of moisture from the skin and across adjacent fibres. Aptly, the lenzing fibre has a linear mass density of around 2.2 dtex. The wool fibres are treated to be shrink resistant and the cellulose fibres comprise a fire retardant viscose fibre. The intermediate woven layer 104 is a 2x2 twill weave and defines an open grid structure wherein the warp (Wpint) and weft (Wtint) yarns are approximately aligned with every other respective yarn (Wp_out and Wt_out) of the outer layer, i.e. there are approximately half the number of wool/Lenzing™ yarns 104 relative to the yarns of the outer layer 102 to define a grid structure which is more open than that of the outer layer to provide certain technical effects as described further below. Other suitable weave patterns as described above may be suitable. A yarn count of the intermediate layer is from around 20/2 Nm (1000 dtex) to around 100/2 Nm (200 dtex), and aptly around 60/2 Nm (333 dtex).
The inner woven layer 106 which aptly provides a back surface of the textile material 100 comprises a para-aramid, e.g. Kevlar™, yarn. Aptly the inner layer is made up of 100% para-aramid fibres. A yarn count of the inner layer is from around 50/1 Nm (200 dtex) to around 100/2 Nm (200 dtex), and aptly 100/2 Nm (200 dtex). The inner layer is a 2x2 twill weave, or the like, that defines an open grid structure of the same or similar density in terms of warp and weft spacing to that of the intermediate layer. However, the warp (Wpinn) and weft (Wtinn) yarns of the inner layer 106 are each located at least approximately between adjacent and respective yarns (Wpint and Wt_int) of the intermediate layer 104. As shown best in Figures 1a and 1c, the weft yarns (Wtinn) of the inner layer 106 are located between adjacent weft yarns (Wtint) of the intermediate layer 104 and in the same plane. The warp yarns (Wpinn) of the inner layer 106 are aligned between the respective warp yarns (Wpint) of the intermediate layer 104 whilst being predominantly in a different plane to the warp yarns of the intermediate layer 104.
As shown in Figures 1a to 1c, and in particular the lifting plan of Figure 2, the warp yarns (Wp_inn) of the inner layer 106 occasionally interact with the weft yarns (Wt_int) of the intermediate layer 104 and the weft yarns (Wt_out) of the outer layer 102 to thereby hold the textile material 100 together. Alternate warp ends (Wp_inn) from the Kevlar inner layer 106 weave into the Nomex outer layer 102 and the wool/Lenzing intermediate layer 104 respectively to provide stitching points (as illustrated by the four dark blocks in the lifting plan of Figure 2). This is achieved by those warp ends (Wp_inn) crossing over individual picks (wefts, W_tout and Wt_inn) of the aforementioned outer and intermediate layers 102,104. This action binds the three layers together. Warp ends (Wp_int) from the wool/Lenzing intermediate layer 104 solely interlace with the wool/Lenzing picks (Wt_int) of the intermediate layer. Warp ends (Wp_out) from the Nomex outer layer 102 solely interlace with Nomex picks ((Wt_out) of the outer layer. The weave structure repeats after every sixteen warp ends and every sixteen picks. The warp and weft repeat within that structure repeats after four ends (warp) and four picks (weft). The yarn sequence is Nomex™, Wool/Lenzing™, Nomex™, Kevlar™ for both warp and weft. Therefore, there are four repeats of the yarn sequence within the weave structure repeat. The binding (stitching) point (first dark block from left to right in Figure 2) of the first Kevlar warp end is onto the fifth pick of the weft repeat which is a Nomex pick. This warp end is the fourth of the sixteen end warp repeat. The binding point (second dark block from left to right in Figure 2) of the second Kevlar warp end is onto the tenth pick of the repeat which is a wool/Lenzing pick. This warp end is the eighth pick of the sixteen end warp repeat. The binding point (third dark block from left to right in Figure 2) of the third Kevlar warp end is onto the thirteenth pick of the repeat which is a Nomex pick. This warp end is the twelfth of the sixteen end warp repeat. The binding point (fourth dark block from left to right in Figure 2) of the fourth Kevlar warp end is onto the second pick of the repeat which is a wool/Lenzing pick. This warp end is the sixteenth of the sixteen end warp repeat. The weave structure as illustrated in Figures 1a to 1c for example has a ratio of 2/1/1, i.e. a weave structure of 2 outer picks (i.e. 2 x Wt_out) to 1 middle pick (i.e. 1 x Wt_int) to 1 inner pick (i.e. 1 x Wt_inn). However, other suitable weave structures can be envisaged such as 1/1/1, 3/1/1, 4/1/1, 5/1/1, 6/1/1, 7/1/1, 8/1/1, 9/1/1, 10/1/1 or the like.
In normal use, the open grid structure of each of the three woven layers 102,104,106 allows air to flow between the yarns through the textile 100 and allows the same to 'breath' which in turn helps to dissipate moisture from a wearer's skin through the textile/garment, e.g. a fire-fighter's jacket.
Whilst still being substantially open in normal use, the meta-aramid yarns of the outer layer 102 which have a relatively dense arrangement of yarns compared to the intermediate and inner layers 104,106, provide excellent strength, thermal resistance, UV stability, wearability and abrasion resistant properties to the textile 100, whilst also protecting the underlying layers to such environmental conditions, i.e. UV, abrasion and the like, in normal use.
The Wool/Lenzing™ blended yarn of the intermediate layer 104 provides comfort and moisture management in that the blended yarn is adapted for moisture absorption and dissipation. In particular, the natural wicking properties of Lenzing™ and moisture absorption properties of wool ensures efficient moisture transport from the inner layer 106 of the textile 100 when the same interfaces with a membrane layer of a garment and/or the skin of the wearer depending on the technical application for the textile 100. Wool is hygroscopic, meaning it can hold up to one third of its own weight in moisture without feeling wet, thereby enhancing comfort. The hygroscopic properties of wool help regulate temperature and humidity, creating a buffer area, thereby also enhancing comfort. The chemical building blocks of wool - amino acids - are hydrophilic (water-liking), meaning that they attract and absorb water molecules into the chemical structure of the fibre. Water binds within the wool's structure through the action of hydrogen bonds in a process known as absorption. In addition, wool is inherently antimicrobial and antistatic, enhancing comfort and protection. Furthermore, wool has a helical configuration in the centre of the fibre which acts like a shock-absorbing spring under compression, further enhancing comfort for the end user. By considering the absorption properties of wool, different fibre thicknesses were assessed, to ensure that the wool element of the yarns of the intermediate layer 104 efficiently and effectively transport moisture from one fibre to the next, thereby enabling moisture to spread over a relatively large surface area to dissipate the same faster away from a wearer's skin. The intermediate layer 104 in accordance with certain embodiments of the present invention also ensures moisture in liquid/vapour form is dissipated from the breathable membrane normally associated with Firefighters PPE, allowing a better moisture flow through the textile/garment 100 and reducing the level of moisture next to the skin, therefore reducing the possibility of scald/steam burn injuries. As shown best in Figure 1a, the arrangement of the intermediate layer 104 and inner layer 106 allows a portion of each of the wool/Lenzing™ warp yarns (Wp_int) to occasionally extend between the Kevlar™ warp yarns (Wp_inn) of the inner layer 106 to engage with an inner membrane of a Firefighters PPE or directly with a wearer's skin to thereby provide comfort to a wearer whilst efficiently wicking away any moisture in the form of sweat from the skin.
The inner layer 106 is aptly a Kevlar™ yarn to provide the textile with strength and stability particularly during heat exposure. As shown in Figures 1a to 1c and the lifting and weaving plans of Figures 2 and 3 respectively, the warp yarns (Wp_inn) of the inner layer 106 occasionally extend over predetermined ones of the weft yarns (Wt_int) of the intermediate layer 104 and at different locations predetermined ones of the weft yarns (Wt_out) of the outer layer 102 to thereby stitch up to these layers to connect the three woven layers 102,104,106 together as a three-layer, single woven fabric/textile to offer optimised bulk with improved thermal protection. Furthermore, this construction also ensures the para-aramid Kevlar™ fibres of the inner layer 106 are protected by the outer layer 102 and in turn from environmental conditions, particularly UV exposure in view of its relatively low stability in UV light. The unique construction of the textile in accordance with certain embodiments of the present invention also provides excellent durability, dimensional stability, and tear strength as the three layers 102,104,106 support one another during a tearing motion.
As illustrated in Figures 4a and 4b, during exposure to relatively high heat and flame, such as in a flash over event, the meta-aramid fibres of the outer layer 102 thicken, swell and contract, before carbonizing at around 360°C. This automatic and immediate reaction to a rapid temperature increase, instantly consolidates, bulks up and closes the fabric sett of the otherwise substantially open grid structure of the outer layer 102 to thereby slow/limit heat transfer through the textile 100 towards a wearer's skin to thereby protect the underlying layers 104, 106 of the textile and desirably the skin from the external heat source. This automatic protection in turn significantly reduces the risk of second/third degree burns as a result of moisture, i.e. sweat, located in the vicinity of the skin, converting to steam. In addition, as described above, the arrangement and configuration of the intermediate layer 104 ensures any moisture created at the inner layer 106, e.g. sweat, is efficiently dissipated away from the skin and the efficient air flow through the textile provided by the substantially open structure of each layer in normal use ensures the dissipated moisture is efficiently evaporated to atmosphere to further reduce the risk of any moisture at the skin converting to steam and causing scalding. Furthermore, as a result of the meta-aramid yarns of the outer layer 102 consolidating, the para-aramid yarns of the inner layer 106 become locked into the structure to add additional strength and stability to the textile/garment 100 whilst being protected from heat/flame by the yarns of the outer layer 102.
A fabric/textile material 100 according to certain embodiments of the present invention is further described by way of the following non-limiting examples:

Example 1

The fabric includes three warp layers consisting of warp A having 93% Meta-Aramid (Nomex), 5% Para-Aramid (Kevlar) and 2% Antistatic fibre (P140), warp B having 55% wool and 45% cellulose FR (Lenzing), and warp C having 100% para-aramid. This fabric is woven with two warp A ends to one warp B and one warp C. This is also the same ratio for the weft.

Example 2

The fabric incudes three warp layers consisting of warp A having a PBI/para-aramid blend yarn, warp B having 55% Wool and 45% cellulose FR (Lenzing), and warp C having 100% para-aramid. This fabric is woven with two warp A ends to one warp B and one warp C. This is also the same ratio for the weft.
Certain embodiments of the present invention therefore provide a light weight, comfortable fabric/textile, which is suitable for and provides improved performance in a PPE application, and which uses an open, breathable construction that reacts to its environment to increase thermal protection. The open structure of the textile allows air to circulate through the garment whilst ensuring the efficient dissipation of moisture to reduce discomfort and the effects of heat stress and exhaustion. The configuration of the textile further ensures the risk of scald burns are significantly reduced in the event of a high temperature event. The end user of a garment made from a textile according to certain embodiments of the present invention will feel cooler and dryer with a reduced wear burden. Furthermore, the textile/fabric meets the requirements of EN 469, BS7971-10, AS/NZ4967, NFPA 1971, EN11612 and other FR PPE standards, and also has a weight of less than 500 gsm when combined with a moisture barrier and inner liner for a firefighting garment. The textile according to certain embodiments of the present invention may be used in garments for use in many technical applications, such as wild land fire garments, structural fire garments, electric arc garment, petrochemical garment, urban search and rescue garments, forestry garments, police violent situation garments (e.g. riot), and garments for military use, or the like.

Claims

A fire resistant textile material (100) comprising:
an outer woven layer (102) comprising polyparaphenylene isophthalamide (meta-aramid) fibres or a blend of meta-aramid with polyparaphenylene terephthalamide (para-aramid) fibres;

an inner woven layer (106) comprising polyparaphenylene terephthalamide (para-aramide) fibres; and

characterised in that the material further comprises an intermediate woven layer (104) disposed between the outer and the inner woven layers and comprising a blend of wool fibres and cellulose fibres.
The material as claimed in claim 1, wherein the intermediate woven layer (104) and the inner woven layer (106) each comprise a twill weave defining an open structure.
The material as claimed in any preceding claim, wherein the wool fibres have a thickness of around 15.5µm to around 29.5µm.
The material as claimed in any preceding claim, wherein the blend of wool fibres and cellulose fibres comprises by weight from around 25% wool and 75% cellulose to around 75% wool and 25% cellulose.
The material as claimed in any preceding claim, wherein the outer woven layer (102) comprises a twill weave defining an open structure in normal use.
The material as claimed in any preceding claim, wherein the outer woven layer (102) comprises a yarn count of from around 40/2 Nm (500 dtex) to around 100/2 Nm (200 dtex).
The material as claimed in any preceding claim, wherein the inner woven layer (106) comprises a yarn count of from around 50/1 Nm (200 dtex) to around 100/2 Nm (200 dtex).
The material as claimed in any preceding claim, wherein the intermediate woven layer (104) comprises a yarn count of from around 20/2 Nm (1000 dtex) to around 100/2 Nm (200 dtex).
The material as claimed in any preceding claim, wherein the outer woven layer (102) comprises around 93% meta-aramid, around 5% para-aramid, and around 2% antistatic fibre.
The material as claimed in any preceding claim, wherein the inner woven layer (106) comprises 100% para-aramid.
The material as claimed in any preceding claim, wherein the inner woven layer (106) is connected to the intermediate woven layer (104) and the outer woven layer (102)
The material as claimed in claim 11, wherein warp ends from the inner layer (106) weave into the outer layer (102) and the intermediate layer (104) respectively by crossing over individual picks thereof.
The material as claimed in any preceding claim, having a weight of around 250gsm.
A garment comprising a fire resistant textile material as claimed in any of claims 1 to 13.
The garment as claimed in claim 14, wherein a face surface of the outer layer (102) defines an outer surface of the garment and a back face of the inner layer (106) is contactable with a wearer's skin or an inner membrane layer of the garment.
A method of manufacturing a fire resistant textile material, comprising:
providing an outer woven layer (102) comprising polyparaphenylene isophthalamide (meta-aramid) fibres or a blend of meta-aramid with polyparaphenylene terephthalamide (para-aramid) fibres;

providing an inner woven layer (106) comprising polyparaphenylene terephthalamide (para-aramide) fibres; and

characterised in that the method further comprises providing an intermediate woven layer (104) between the inner and outer woven layers, wherein the intermediate woven layer (104) comprises a blend of wool fibres and cellulose fibres;
The method as claimed in claim 16, further comprising connecting yarns of the inner woven layer (106) with yarns of the intermediate woven layer (104) and the outer woven layer (102)
The method as claimed in claim 17, wherein connecting comprises interweaving warp ends from the inner layer (106) into the outer layer (102) and the intermediate layer (104) respectively by crossing over individual picks thereof.
The method as claimed in any of claims 16 to 18, wherein the intermediate woven layer (104) and the inner woven layer (106) each comprise a twill weave to define a substantially open structure.
The method as claimed in claim 19, wherein the outer woven layer (102) comprises a twill weave defining a substantially open structure in normal use.