This invention relates to fire resistant textile materials and garments made from these materials. The invention relates particularly but not exclusively to articles of clothing for use by fire fighters and for textiles for manufacture of such clothing. European legislation requires employers to provide garments which protect their employees against hazards to which they may be exposed. Clothing for protection against heat and flame must pass minimum performance requirements for flame, radiant heat, heat resistance, tensile and tear strength, abrasion resistance and penetration by water and liquid chemicals. The assembled garments must achieve levels of resistance to heat transfer by both flame and radiant heat.

One of the most effective ways to reduce second and third degree burns is to make sure that the barrier of protective clothing between the heat source and the skin remains intact during exposure. This is referred to as the break open resistance or non-break open protection. An object of the present invention is to optimise thermal protection and wear properties provided by the fabric. We have discovered that this can be achieved through use of enhanced fabrics design and fibre utilisation.

Outer textile materials for fire fighting clothing have previously been manufactured from 100% meta-aramid or polyamideimide, blends of polyparaphenylene isophthalamide (meta-aramid) and polyparaphenylene terephthalamide (para-aramid) fibres or by use of spun yarns or staple mixtures with polyparaphenylene terephthalamide copolymer or fibres for example comprising para-aramid cores with meta-aramid or polyamideimide covers. The combination of these fibres in the fabric enhances the non-break open protection of the product. However meta-aramid and polyamideimide fibres shrink, consolidate and thicken when exposed to a high temperature heat source. The presence of para-aramid or a copolymer thereof in either the fibre blend or as a core can be used to prevent fibre shrinkage and consequent breaking open of the garment. However the inclusion of para-aramid fibre in the blend has been found to be insufficient in tightly woven fabrics to prevent breaking open. Consequently there is a need for improved textile materials for manufacture of fire fighting garments and the like. Fire fighting garments have been made from a plurality of textile layers, including an outer layer of woven meta-aramid fibre, for example as manufactured under the trade mark Nomex. Break open protection may be afforded by blending with para-aramid fibres, eg as manufactured under the trade mark Kevlar and as disclosed in US 3063966 and US 3506990. However charring of such blends may lead to cracking and embrittlement with consequent deterioration of physical properties.

WO 00/60823 discloses a fire resistant textile material comprising a woven face fabric composed of fibres selected from meta-aramid, polyamideimide and mixtures thereof, the fabric including a woven mesh of low thermal shrinkage fibres, preferably polyparaphenylene terephthalamide (para-aramid eg Kevlar).

According to the present invention a fire resistant textile material comprises a woven face fabric and a back fabric;

wherein one or both of the warp and weft of the woven face fabric comprises

(a) spun or multifilament yarns composed of a mixture of polybenzimidazole (PBI) and polyparaphenylene terephthalamide (para-aramid) fibres; and

(b) spun or multifilament yarn composed of a mixture of polyparaphenylene isophthalamide (meta-aramid) and para-aramid fibres;

and wherein the warp of the backing fabric comprises para-aramid yarns and the weft of the backing fabric comprises a mixture of para-aramid and PBI yarns.

The yarns (a) and (b) may be independently a spun yarn or two or more spun yarns twisted yarns together. Use of spun yarns is preferred.

Polybenzimidazole (PBI) fibres are flame resistant, will not burn or melt and exhibit low shrinkage when exposed to a flame. However PBI has poor abrasion resistance making use in fire fighters garments uneconomic as the working life of a garment is reduced in relation to other fabrics.

Fabrics in accordance with this invention provide a beneficial combination of fire resistance, physical wear and light fastness properties.

In preferred embodiments both of the warp or weft yarns of the face fabric comprise para-aramid and PBI yarns. Preferably the warp or weft yarns may independently comprise 30% to 60% PBI (by weight), more preferably 30% to 50%, more preferably 30% to 45%. For example, the warp or weft yarns may comprise 50% PBI (by weight), more preferably 45% typically 34%. The total PBI content of the fabric may be in the range of 25% to 40% PBI (by weight), more preferably 25% to 35%, more preferably 28% to 35%. For example, the warp or weft yarns may comprise 50%, preferably up to 45%, typically up to 34% PBI.

The warp yarns may have the same count and composition or may be independently selected within the above ranges.

The face yarns may comprise repeating regions of (a) and (b) yarns. For example alternating regions may be employed in which each region consists only of (a) or (b) yarns. Alternatively the regions may each consist of a particular combination of (a) or (b) yarns. For example the first region may be composed of 60% PBI, 35% para-aramid and 5% meta- aramid and regional (b) may be composed of 10% PBI, 85% para-aramid and 5% meta- aramid.

Usually two regions are employed each region being of a particular fibre composition. In alternative embodiments three or more regions having different combinations of (a) and (b) fibres may be employed.

In fabrics in which two regions are employed, the first region may consist of m yarns and the second region may consist of n yarns wherein m and n are integers, so that a repeating unit of m plus n yarns is present.

The first region may be a lower thermal shrinkage region and the second region may be a higher thermal shrinkage region. The lower thermal shrinkage region may comprise a mixture of PBI, para-aramid and an option further fibre, for example meta-aramid, or PBO.

The higher thermal shrinkage region may comprise a mixture of para-aramid, meta- aramid and an optional further fibre, for example PBI or PBO. The yarns are preferably selected so that the total amount of PBI in the fabric is within the range of about 25% to about 40%, preferably about 28%> to about 40%>, more preferably about 28% to about 35% by weight. In a first embodiment the face warp and weft yarns comprise an alternating array of first regions consisting of six (a) yarns and second regions comprising two (b) yarns. Consequently the weft plan consists of repeating units of eight yarns.

The ratio of yarns m:n is selected so that the face comprises a majority of the PBI fibres in order to prevent excessive carbonisation upon exposure to a flame.

If the first region consists of m (a) yarns and the second region consists of n (b) yarns, a preferred ratio of m:n is in the range 8 to 2:1 ; more preferably 10 to 3: 1. Preferred exemplary ratios are 6:2; 3: 1 ; 9:3; 5:2; 7:2 and 8:2.

A ratio of 9:3 may produce larger raised regions.

A ratio of 8:2 may produce less frequent raised regions. In particularly advantageous embodiments both the warp and weft fibres have first regions of m yarns and second regions of n yarns.

An advantageous feature of a fabric in accordance with this invention is that the inter sections of the first regions of m yarns may be raised higher from the fabric surface in relation to the adjacent surrounding second regions of n yarns. The raised regions have greater resistance to abrasion and accordingly protect the surrounding regions from wear in use, prolonging the working life of the fabric.

The invention has a particular advantage in that the values of m and n may be selected to control the volume of air entrapment afforded by the fabric.

In a particularly advantageous embodiment the back fabric may serve to provide a scaffolding located beneath the regions (b), para-aramid and meta-aramid yarns, of the face fabric. Such a configuration assists in raising the profile of the raised regions. Furthermore the appearance of the fabric in use is enhanced. The back fibres are hidden beneath the (b) fibres so that the appearance of the fabric is maintained as the colour of the backing fibres fades following repeated washing.

A preferred back fabric may comprise a warp of 100% para-aramid and a weft of 40% PBI and 60% para-aramid yarns by weight. Alternatively the weft may be 100% para-aramid and the warp 40%» PBI at 60%> para-aramid.

The back fabric serves a further function of holding the face above an underlying garment lining. Structural integrity is enhanced. Active air entrapment is also enhanced.

In a preferred embodiment the face yarns count may be in the range of resultant 15 to 50 Nm (Numero metric, including single or multiple folding of yarns), preferably 20 to 41 Nm. The reverse side yarns count may be in the range 25 to 150 Nm, preferably 40 to 60 Nm (Numero metric, including single or multiple folding of yarns).

The proportion of PBI by weft yarn count may be 40/2.

Independently the proportion or ratio of face to back yarns by number may be 2: 1 to

20: 1.

The interlacing of the face weave may be determined by the desired appearance and the physical properties required of the final fabric. This interlacing may be any of a number of designs known to those skilled in the art. The preferred face weaves are plain weave, plain weave rip stop, twill weave rip stop or straight twill weaves and their derivatives. A rip stop weave is especially preferred. Some other cloth and weave variations are:

Self Stitched Double Cloths;

Face weaves - lxl, lxl Rip Stop, 2x1 Twill, 2x1 Twill Rip Stop and their derivatives.

Back weaves -lxl, 2x1 Twill and their derivatives.

Centre Stitched Double Cloths (Centre stitching may be warp or weft stitching or if both this then becomes a treble cloth):

Face and Back weaves as for Self stitched cloths: Interchanged Double Cloths:

Face and Back weaves may be the same or similar to maintain a regular face effect e.g. lxl or 2x1 Twill although they could be different if required e.g. Face 2x1 Twill, Back lxl, this would however give a patterned effect.

Multiple Cloths: These may combine more than two layers of fabric for example triple cloths, quadruple cloths etc.

Each layer of fabric could utilise combinations of the weaves listed above. Other weaves may be used if the requirements to do so arises. The degree of interlacing between the face side yarn ^' s and the reverse side yarns is important to achieve a fabric which maximises the different properties of these yarns, gives a level surface and pleasing appearance and yet can be woven with the highest possible efficiency.

In a preferred method the yarns for the warps of both the face and reverse sides of the fabric may be assembled in the specified proportions and order of working by the sectional warping process onto one or two warp beams jointly having the total number of ends required to weave the final fabric.

The weft yarns may be inserted across and interlaced with the warp yarns in the specified proportions, order of working and density selected to produce the required face and reverse side weaves.

Preferred fabrics include a proportion of compact spun long staple yarns. Compact spun long staple yarns exhibit improved tensile strength as measured by BS EN IS013934-1. Compact spun yarns are manufactured by a process in which air is withdrawn from the fibre through the drafting stage. Also the yarn may be made from stretch broken fibres/TOW, that is stretched in the fibre process and broken at weak points. This may afford a strength improvement of 30-40% typically 35-37% in the warp and 35-45%, typically 40-45% in the weft.

The strength is also improved as measured by BS EN IS013937-2. This gives a significant improvement, mainly in the weft. This may be attributed in part to the grid on the reverse of the fabric and in the weft direction being composed of a proportion of PBI. Pilling in accordance with BS EN ISO 12945-1 and abrasion resistance in accordance with BS EN IS012947 are also significantly improved in comparison to previously disclosed fabrics. Preferred fabrics exhibit fire resistant properties, including break open resistance and longevity compared to fabrics comprising Nomex PBI. Thermal resistance is superior to other PBI fabrics.

Resistance to ultraviolet degradation is greater than for other PBI woven fabrics. In particular ultra-violet discolouration is diminished.

Abrasion resistance is also enhanced, particularly for fabrics having upwardly extending picks and ends of meta-aramid which form dimples across the surface of the fabric to provide protection for the adjacent yarns. This provides significantly improved abrasion resistance in comparison to other PBI woven fabrics.

Use of low thermal shrinkage fibres in accordance with the present invention increases the residual tensile strength of the textile material following exposure to flame or a radiant heat source. Low thermal shrinkage fibres in accordance with this invention may be defined as a fibre which exhibits not more than 6% shrinkage when exposed to a temperature of 400°C for a period of 5 seconds.

Fibres or yarns composed of 100% polyparaphenylene isophthalamide meta-aramid (eg Nomex) (consolidate during exposure to high pyrolysis temperatures, for example in excess of 375°C. This consolidation is due to the nature of aromatic structures having low or non-thermoplasticity and high char forming which can result in a whole garment charing when exposed to a flame. The low or non-thermoplasticity fibres, for example para-aramid fibres or yarns do not shrink to the same extent on exposure to this temperature. (The thermal shrinkage of Kevlar is about 3%, whilst the thermal shrinkage of Nomex is about 24%). If the two fibres or yarns are combined in a fabric, the shrinkage of the fabric may be controlled and/or restricted in such a way that the formation of holes, or break opening, is minimised. The degree of the distortion of the fabric in the cross-sectional direction when exposed to a high temperature may be controlled so that the fabric becomes thicker. Control is achieved by use of a woven face fabric. This serves to increase the thermal protection afforded by the fabric and increases the number of seconds needed to raise the temperature on the inner side to a level which would create pain or a second degree burn on human skin or on the type of sensor used in Thermal Protection Procedure (TPP) testing. Fabrics in accordance with the present invention have the advantage that degradation of the low thermal shrinkage fibres, which are more susceptible to ultra-violet light degradation than other fibres, is reduced because they are not located on the outer surface of the fabric. In preferred embodiments of the invention the low thermal shrinkage fibres form an interwoven backing scrim on the back of the face fabric. The low thermal shrinkage fibres preferably comprise para-aramid or polyparaphenylene terephthalamide copolymer, eg Kevlar yarns. The thickness of the yarn may be selected in accordance with the resultant mass and weave of the finished fabric. The resultant mass (g/m ² ) will vary dependent on the particular end use but will generally be within the range 150 to 300 g/m , preferably between 210 to 230 g/m ² .

The woven fabric is preferably a combination of a face fabric into and an interwoven backing scrim. The weave of the face fabric may vary dependent upon the mass and end use required. The interweaving of the backing scrim will be dependent on the weave of the face fabric and the thermal performance required.

Fabrics in accordance with this invention may be produced by interweaving yarns which have been spun and plied or core spun from staple fibres and/or multifilament fibres which may comprise meta-aramid, para-aramid, PBI, PBO or intimate blends of any combination of these fibres. The interweaving of the selected yarns may be such that a closely woven fabric suitable for use as the outer face of a garment is combined with a loosely woven fabric which is suitable for use as the reverse side of the garment.

The selection of fibres and yarns which may be incorporated into fabrics in accordance with this invention will take account of the different shrinkage properties of these fibres and the particular requirements of the final fabric. A combination of high and low shrinkage fibres may be chosen.

The proportion and count of face side yarns to reverse side yarns may be determined by the required weight of the final fabric, the interlacing of the face weave and the degree of effectiveness required from the properties of the reverse side yarn. In a preferred embodiment the face yarns count may be in the range of resultant 15 to 50 Nm (Numero metric, including single or multiple folding of yarns), preferably 20 to 41 Nm. The reverse side yarns count may be in the range 25 to 150 Nm, preferably 40 to 60 Nm (Numero metric, including single or multiple folding of yams). Independently the proportion or ratio of face to back yarns by number may be 1 to

20: 1, preferably 8 to 12: 1.

The interlacing of the face weave may be determined by the desired appearance and the physical properties required of the final fabric. This interlacing may be any of a number of designs known to those skilled in the art. The preferred face weaves are plain weave, plain weave rip stop, twill weave rip stop or straight twill weaves and their derivatives.

Figure 1 shows a weaving plan for a preferred fabric. Other weaves may be used if the requirements to do so arise. The degree of interlacing between the face side yarns and the reverse side yarns is important to achieve a fabric which maximises the different properties of these yarns, gives a level surface and pleasing appearance and yet can be woven with the highest possible efficiency.

In a preferred method, the yarns for the warps of both the face and reverse sides of the fabric may be assembled in the specified proportions and order of working by the sectional warping process onto one or two warped beams jointly having the total number of ends required to weave the final fabric.

The weft yarns may be inserted across and interlaced with the warp yarns in the specified proportions, order of working and density selected to produce the required face and reverse side weaves.

Differential tension may be applied to the face and reverse side yarns during the weaving process and during the insertion of the weft. This is important to compensate for the varying degrees of elongation which are inherent in the different types of fibres used in those yarns and which are important to the properties of the fabric of this invention.

A preferred weaving machine which may be used to produce fabric of this invention is one that will supply the face and back warp yarns from individual warp beams at different fed rates to compensate for the varying degrees of elongation and the varying inter-lacings of the face fabric yarns and reverse side yarns. Fabrics of this invention have the advantage of additional strength in the fabric structure compared to other PBI woven structures of equivalent weight and end use due to the compact spinning and woven structure increasing its tensile strength. Abrasion resistance is improved making the structure more breathable for longer due to the structure protecting the PBI in the form of the high points of the rip stop and the compact spun yarns making fibrillation less easy and keeping the structure clear for the passage of air and moisture through the structure.

Improvements also result from the use of the unique construction of interlacing the Nomex and PBI to protect the PBI from UV exposure and subsequent molecular degradation. This UV degradation is a known performance inhibitor for PBI over time.

The invention is further described by means of example but not in any limitative sense, with reference to the accompanying drawings, of which:

Figure 1 is a weaving plan for a fabric in accordance with this invention, and

Figure 2 is a plan view of a fabric in accordance with this invention. Example 1

The yarn plan of the fabric shown in the Figures is the same in the warp and weft directions.

Warp A and Weft A are para-aramid (Kevlar )/PBI yarns.

Warp B and Weft B are a meta-aramid (Nomex)/para-aramid (Kevlar) yarns. Warp C is a 100% para-aramid (Kevlar) backing scaffolding yarn.

Weft C is a para-aramid (Kevlar)/PBI backing scaffolding yarn.

Raised regions are formed where the warp and weft B and C yarns intersect. The backing warp and weft yarns C lie behind the face yarns except at their intersections in the raised regions. The ratio of m:n is 2:6. A textile material in accordance with the present invention was woven using a self- stitched double construction, with a blend of a 93% meta-aramid, 5% para-aramid and 2% antistatic fibre (Nomex Delta C) yarn and 60% para-aramid and 40% PBI yarn as a plain weave ripstop face and a 100% para-aramid (Kevlar) warp and 60% para-aramid and 40% PBI weft, plain weave back, is woven in the proportion of six face threads to one back thread.

A fabric was woven using double beam weaving with a 24 Reed Sley 2,2,2,3. Warp comprised 3717 ends consisting of 2478 ends of Nm40/2 PBI/Kevlar, 826 ends of Nm40/2 Nomex coloured Paris Blue and 413 ends of NmlOO/2 Kevlar coloured Gold KV0005.

The weft comprised Nm40/2 Nomex Comfort N307 coloured Paris NX0238, Nm40/2 PBI/Kevlar, Natural coloured and Nm40/1 PBI/Kevlar Natural coloured. The weaving plan shown in Figure 1 comprises 8 shafts drafted.